Tesis sobre el tema "Silver fir"

When making decisions on which areas to harvest in a sustained yield, even-flow manner in mountainous areas such those in coastal British Columbia, it is important to know how timber productivity changes with elevation. This information allows foresters to decide at what elevation to start increasing the rotation age and to decide at what elevation sustainable harvesting becomes infeasible due to low productivity. Since Pacific silver fir (Abies amabilis Dougl. ex Forbes) has an elevation range that extends from sea level nearly to the tree line (0 m to approximately 1,650 m; from the Coastal Western Hemlock zone, through the Mountain Hemlock zone; to the lower limits of the Alpine Tundra zone), productivity-elevation relationships are especially important. To acquire quantitative measures of productivity decrease with increasing elevation a regression equation relating site index (the height of the dominant trees at a base age of breast height age of 50 years) to elevation in southern coastal BC was developed. In turn, we used this regression as an input into the height driven yield model named the Variable Density Yield Prediction model (VDYP). The use of the VDYP model allows the site index values to be translated into actual productivity measures (e.g., volume per hectare, mean annual increment at culmination age).

Ecosystem-specific forest management requires comprehension of tree species productivity in managed settings, and how this productivity varies with the ecological determinants of site quality, i.e., the environmental factors that directly affect the growth of plants: light, heat, soil moisture, soil nutrients, and soil aeration. A good understanding of this variation is necessary for making species- and site-specific silvicultural decisions to maximize productivity. Productivity of a given species is usually measured by site index (tree height at 50 years at breast height age). Quantitative relationships between site index and these measures of site quality provide predictive models for estimating site index. Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in the coastal forests of British Columbia. In relation to climate, its range in southwestern British Columbia extends from sea level to almost timberline, and from the hypermaritime region on western Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. In relation to soils, its range extends from slightly dry to wet sites and from very poor to very rich sites. In view of this relatively wide climatic amplitude, a large variability in productivity can be expected. It is particularly important to consider the growth performance of Pacific silver fir when decisions are made regarding whether or not to cut stands on high-elevation sites. In the study summarized here, relationships between Pacific silver fir site index and selected ecological measures of site quality were examined, and site index models using these measures as predictors were developed.

This thesis describes patterns of variation in several cone, seed and seedling characteristics of Pacific silver fir (Abies amabilis [Doug.] Forbes) sampled from Vancouver Island, B.C. Cone collections kept separate by tree were made at eight locations during the fall of 1983 to provide material for the study. The inheritance patterns of 13 enzyme loci were determined from seed tissues of 87 trees, and seven loci were found to possess at least two allozyme variants. These loci conformed to the assumptions of Mendelian-type inheritance, although AAT-2 displayed marked segregation distortion. No linkage groups could be established at the sampling intensity available (20 seeds per tree). Significant levels of inbreeding, based on a multilocus estimate of outcrossing, were detected in five of seven populations and indirect evidence suggests related matings other than selfing may be occurring. Variation among populations in outcrossing rate was evident (0.725 < tm ≤ 1.0) and appears positively correlated with seed size (measured by 1000-seed weight). High levels of allozyme variation were found to exist within populations (95-98%) and estimates of the extent of population differentiation were shown to differ depending upon the particular analytic method employed. Maternal (extant) trees appeared more heterozygous than did viable embryos and populations sampled on southern Vancouver Island appeared more genetically diverse than did populations sampled on northern Vancouver Island. A sub-sample consisting of two populations, each with seven trees, from northern, mid and southern Vancouver Island provided material for a germination test and open-pollinated progeny study. Seed dormancy was not pronounced among populations. Large family differences in germination responses were detected, irrespective of pregermination treatment, suggesting a high degree of genetic control of germination in Pacific silver fir. Anomalous germination behavior in one population was attributed to sub-optimal stratification conditions and proliferation of mold. Improvement in production of seedlings of Pacific silver fir may be achieved by collecting and germinating seeds on a family-by-family basis. Germinants from the first count of the germination test provided open-pollinated progeny for measurement of growth variables. Seedlings were grown in a greenhouse alongside production Abies stock for 29 weeks. Population differences accounted for a considerable part of variance in cone and seed size. The effect of population on height of seedlings at eight weeks was significant but declined to virtually zero by the end of the test. Populations had negligible influence on growth rate of seedlings as well. Variation in growth rate among open-pollinated families was statistically significant but accounted for only 20% of the total variation. Significant population differences were detected in root weight of harvested seedlings. Family differences in this and other biomass variables were at most 20%, with the majority of variation in seedling growth traits residing within families.
Forestry, Faculty of
Graduate

Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in coastal forests of B.C. Its range extends from sea-level to almost timberline, and from the hypermaritime region on the west coast of Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. With this relatively wide climatic amplitude, a large variability in the height growth pattern of Pacific silver fir can be expected, since climate is considered to be the most influential determinant of the trajectory of height over age of forest trees. This variability, however, is not reflected in the height growth curves and site index tables used to estimate Pacific silver fir site index, since the curves and tables were developed from low-elevation stands on Vancouver Island. Consequently, when these curves and tables are applied to high-elevation or submaritime stands, we get biased estimates of site index. Accurate estimates of site index are necessary for accurate yield predictions. Furthermore, they are essential for making rational decisions about whether to cut the forest in situations where potential tree growth is marginal, such as in high-elevation forests.

This study examines the influence of climate on tree-ring properties of several major tree species: Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and lodgepole pine (Pinus contorta var. latifolia Dougl. ex Loud.). Our three objectives were to determine how (1) tree-ring properties change along an elevation gradient, (2) short-term climatic influences are correlated with tree-ring properties, and (3) long-term climatic influence on tree-ring properties.

Silvergran, Abies alba, är en ursprungligen odlad art som har fått snabb spridning i södra och mellersta Sverige de senaste 100 åren. Risk finns att denna art är invasiv och kan påverka vår inhemska flora och fauna negativt. I ett lövskogsområde norr om Uppsala finns en ungefär 70 år gammal plantering av silvergran som är nära 1200 kvadratmeter stor. I området kring planteringen har ett stort antal plantor av silvergran etablerat sig och syftet med denna studie är att kartlägga spridningen av arten i området. Studien kan bidra till att skapa ett generellt spridningsmönster för silvergran i liknande miljöer i Sverige. Att kartlägga spridningsmönstret kan vara fördelaktigt både för att kunna avgöra om arten måste klassas som invasiv, och om åtgärder behöver vidtas mot den möjligt invasiva ädelgranen. Skogsområdet är omgivet av åkermark och har inventerats genom transekter indelade i rutor. Från inventeringen är en generell spridning av silvergran kartlagd för skogsområdet. Granarna uppmättes i olika storlekskategorier, vilket är representerat i de framställda kartorna. På så sätt får man direkt en visuell överblick över spridningen av silvergran i skogsområdet från ursprungskällan. Tydligt är att silvergranen har stor möjlighet att på egen hand sprida sig i den sydliga, svenska lövskogen och hur spridningen av silvergran i framtiden kommer se ut är ett ämne för diskussion och studier.

In the wetter climates associated with the coastal forests of northwestern North America, coarse woody debris (CWD) accumulations in the form of snags, downed boles, and large branches can be large in natural forest ecosystems. Seedlings often regenerate on stumps and downed logs in the understory of old-growth coastal forests. The question remains though, whether CWD is a necessary component for seedling survival and growth in forests managed for commodity production. This study addresses one concern of forest managers: is there an immediate nutritional or moisture supply advantage conferred by CWD for the survival and growth of seedlings in the coastal climate of British Columbia? We compared survival and growth of seedlings planted in decaying wood compared to non-woody humus forms and mineral soil under heavy shade and full light conditions. Low light environments are of particular interest since reports of the strong association between CWD and regeneration has primarily referred to understory seedlings and saplings in old-growth forests.

La fenologia studia le fasi biologiche ricorrenti nel ciclo vitale di piante ed animali e le loro relazioni con i fattori ambientali. Le fasi fenologiche, quali fioritura e riattivazione dei processi di crescita che avvengono nei meristemi primari e secondari, determinano l’accrescimento annuale delle piante. Il cambiamento climatico è un fattore che condiziona la vulnerabilità delle piante in vari aspetti, compresa la fenologia. É indispensabile, quindi, migliorare ed integrare le attuali conoscenze degli eventi fenologici nei due meristemi, le relazioni tra essi ed con i fattori ambientali. Comprendere gli effetti dei fattori climatici, quali temperatura e precipitazioni, sulla fenologia delle piante è uno step essenziale per stabilire un link tra il cambiamento climatico in atto e le risposte fenologiche. Questi approcci possono produrre previsioni affidabili inerenti gli adattamenti fisiologici delle piante in una prospettiva di lungo termine. In questa tesi si è proposto di analizzare la fenologia dei meristemi in conifere lungo gradienti latitudinali ed altitudinali, per comprendere più a fondo le loro risposte ed adattamenti ai cambiamenti climatici. Diverse metodologie sono state utilizzate per indagare la fenologia: dalle analisi anatomiche ed osservazione diretta in campo all'osservazione satellitare. Inoltre, è stata indagata la tempistica delle fasi fenologiche considerando futuri scenari climatici, attraverso un approccio modellistico. É stato ipotizzato che la variazione nelle fasi fenologiche dell’accrescimento meristematico verificatasi a diverse latitudini e altitudini, può essere spiegata dalle condizioni climatiche specifiche del sito e loro rispettive variazioni. In questo lavoro sono stati selezionati 10 siti di studio lungo gradienti latitudinali ed altitudinali. Sette di questi sono situati in foresta boreale (Quebec, Canada), mentre gli altri tre siti si trovano nel bacino del Mediterraneo, lungo la penisola italiana. Tutti i siti sono caratterizzati da boschi di conifere, dominati da abete balsamico [Abies balsamea (L.) Mill.] pino nero del Canada [Picea mariana (Mill.) BPS] in foresta boreale, e dall’abete bianco (Abies alba Mill.) per le foreste montane mediterranee. In tutti i siti è stata effettuata la raccolta di microcarote al fine di analizzare la fenologia dello xilema, mentre in foresta boreale è stata studiata la fenologia dei getti attraverso sia osservazioni dirette in campo che da immagini telerilevate. Lo studio ha correlato le fasi fenologiche di sviluppo dei germogli e la differenziazione dello xilema. Questo rapporto è stato, inoltre, analizzato tra cronologie a lungo termine della crescita dello xilema e la fenologia vegetale rilevata dal Normalized Difference Vegetation Index (NDVI). Infine, si è verificato quanto la fenologia dello xilema possa essere influenzata dalla temperatura e dalle precipitazioni. I risultati ottenuti hanno fornito nuove conoscenze sulla dinamica della fenologia primaverile e preziose informazioni sui sincronismi tra i due meristemi per le specie boreali. Inoltre, lo studio ha dimostrato l'importanza di definire con precisione le fasi di sviluppo del germoglio per analizzare correttamente i rapporti con la fenologia dello xilema. Le analisi delle cronologie di lungo termine hanno dimostrato che la formazione dello xilema potrebbe essere opportunamente stimata su larga scala geografica utilizzando i dati telerilevati. Inoltre, la temperatura risulta essere il principale driver delle fasi fenologiche dei due meristemi nella foresta boreale. Diversamente, lungo la penisola italiana, le precipitazioni durante la stagione di crescita, insieme con la temperatura minima, sono le variabili più importanti nell’influenzare la durata delle fasi fenologiche. La risposta delle piante alle future condizioni ambientali dovrebbe essere attentamente studiata localmente, perché questa interazione può essere utilizzata nella pianificazione delle strategie di gestione forestale adattiva.
Phenology is the study of recurring biological events that involve plants and animals and their relationships with the environmental factors. The phenological phases, such as flowering and growth reactivation, occurring in primary and secondary meristems, determine the annual plant development. Climate change is one of the factors that may alter the vulnerability of trees in several aspects, including the phenology. A better understanding of the phenological events occurring in the two meristems, the relations between them and the environmental factors is necessary. Understanding the effect of the climatic factors, such as temperature and precipitation, on plant phenology is an essential step to establish a link between recent climate change and phenological responses. These approaches can produce reliable predictions about future plant responses in a long-term perspective. The objective of this thesis was to analyse the phenology of meristems in conifers along latitudinal and altitudinal gradients, to deeper understand their responses to climatic drivers. Different methodological approaches were used to investigate the plant phenology: from anatomical analyses and direct observation in field to satellite observation. Moreover, the timing of phenological phases under future climatic scenarios were explored. A general hypothesis of this study was that a time variation in the phenological phases of growth meristems could be observed among different latitudes and altitudes; it was then verified if the variation hypothesized can be explained by site-specific climatic conditions and their changes in time. In this thesis, 10 study sites located along a latitudinal and altitudinal gradients were selected. Seven of these are located in the boreal forest of Quebec (Canada), while other three sites are located in the Mediterranean area, along the Italian Peninsula. All the sites are characterized by forest stands dominated by coniferous: balsam fir [Abies balsamea (L.) Mill.] and black spruce [Picea mariana (Mill.) BPS] in the boreal forest, and silver fir (Abies alba Mill.) in the Mediterranean mountain forest. Micro-cores were collected in all the sites with the aim to analyse the xylem phenology, while the bud phenology was studied in the boreal forest, through direct and satellite observation. The study correlated the phenological phases of bud development with the xylem differentiation. This relationship was also analysed between long-term chronologies of xylem growth and the timing of plant phenology detected by Normalized Difference Vegetation Index (NDVI). Furthermore, the relationships between xylem phenology with temperature and precipitation were explored. The results obtained provided new knowledge on the dynamics of spring phenology and novel information on the synchronisms between the two meristems for boreal tree species. Moreover, the realized study demonstrated the importance of precisely define the phases of bud development in order to correctly analyse the relationships with xylem phenology. The analyses of long-term chronology demonstrated that the timing of xylem formation could be suitably estimated at wide geographical scale using remote sensing data. Furthermore, temperature resulted the main driver on phenological phases of the two meristems in the boreal forest. Differently, the precipitation during the growing season together with minimum temperature were the most important variables that affected the duration of phenological phases in the Italian study sites. Response of trees to future environmental conditions should be carefully studied locally, because this interaction can be used for planning adaptive forest management strategies.

El decaïment de l'avet (Abies alba) va començar als anys 90 als Pirineus espanyols sense una
causa clara que l'expliqués. Les condicions climàtiques de la darrera part del segle XX semblen estar associades al començament d'aquest fenomen. Paral·lelament als processos de decaïment, apareixen nombroses alertes de plagues i patògens que afecten aquests boscos, fet que fa necessari conèixer la relació entre aquests agents biòtics i l'actual decaïment. Els Pirineus han estat utilitzats per l'home durant segles; la gestió i la dinàmica dels Pirineus, han de ser també considerats quan es pretén i) entendre si les condicions ambientals, la gestió i la dinàmica forestal estan associades a l'actual decaïment de l'avet, parant especial atenció al paper que determinats patògens com ara Viscum àlbum, Armillaria, Heterobasidion annosum i Melampsorella caryophyllacearum puguin tenir en el procés, mitjançant; ii) l'estudi de la seva epidemiologia i la identificació de quina és la gestió associada a la seva incidència i severitat.
Es van mesurar 29 parcel·les escollides a l'atzar en avetoses dels Pirineus. A cada una de les parcel·les es va mesurar el decaïment dels arbres i la presència de patògens o plagues. Es va
mesurar, també, la incidència d'Armillaria i H.annosum a l'interior dels arbres, mitjançant el cultiu de cilindres de fusta extrets de l'interior del tronc. Es va mesurar la presència de patògens a les soques i als arbres morts. Les soques i els arbres morts van ser utilitzats per estimar la composició d'espècies arbòries que hi havia en un passat. Es van mesurar 42 variables per tal de descriure els arbres, les condicions ambientals i la gestió que s'havia dut a terme en cada una de les parcel·les. Es van recollir mostres d' Armillaria i H. annosum, es van cultivar i es van identificar mitjançant tècniques moleculars d'anàlisi de l'ADN. Per examinar algunes de les hipòtesis plantejades va ser necessari emprar models mixtos no lineals a causa de la falta de normalitat i de la correlació espacial de les dades. Un 15% i un 10% dels avets dels Pirineus estaven defoliats i cloròtics, respectivament. Els arbres de l'estrat dominant eren els que presentaven més decaïment. Cap característica de la massa es va trobar associada al decaïment dels arbres. Es va observar que l'avet havia augmentat la seva àrea basimétrica en els últims anys i que els pins (Pinus sylvestris i P. uncinata) n'havien perdut. Les pèrdues d'àrea basimétrica de l'avet van ser, en la majoria dels casos, degudes a augments d'àrea basimétrica de faig (Fagus sylvatica); aquest fet es va trobar associat a la presència de danys sobre la regeneració d'avet produïts per ungulats. La presència de V. album es va veure associada a la mortalitat i al decaïment de l'avet. En boscos purs es va observar que V. album s'havia dispersat fàcilment entre i dins dels arbres, però en masses mixtes la dispersió de V. album semblava significativament reduïda. H. abietinum va ser identificat als Pirineus i la seva severitat a les soques era més alta en aquells boscos on les tallades havien afectat un major percentatge d'avet respecte a altres espècies forestals. La presència de H. abietinum es va veure associada amb la presència de V. album. La mortalitat d'avet era més gran quan els dos patògens apareixien junts. El rovell M. caryphyllacearum es va trobar associat al decaïment de l'avet. Aquest és un fong comú als Pirineus i la seva severitat era més alta en masses amb una major presència de plantes tolerants a l'ombra al sotabosc. A. cepistipes és l'espècie del gènere Armillaria més freqüent a les avetoses. A. ostoyae es va trobar més freqüentment en masses situades a major altitud, i on l'avet estava colonitzant més ràpidament altres tipus de bosc. El decaïment de l'avet és relativament baix i és més evident en els arbres dominants de la massa, cosa que suggereix que es podria tractar d'aquells arbres deixats després de les tallades com a arbres de llavor. V. album sembla ser el patogen amb un paper més important en el decaïment de l'avet. La seva severitat podria estar associada a l'augment de la temperatura als Pirineus i podria haver estat afavorida per la presencia de H. abietinum. Armillaria sembla tenir un paper notable en la dinàmica dels boscos de pi i avet. M. caryophyllacearum sembla trobar unes millors condicions per infectar avets en masses tancades que en masses obertes. Un augment de la sequera als Pirineus sembla que ha incitat
el decaïment de les avetoses. La gestió sembla que en general ha afavorit l'avet, però podria haver predisposat determinats arbres a decaure. L'augment de la diversitat d'espècies i la reducció de la competència s'haurien d'examinar com a possibles tècniques per augmentar la salut d'aquests boscos.
El decaimiento del abeto (Abies alba) empezó en los años 90 en los Pirineos sin una causa clara que lo explicara. Las condiciones climáticas de la última parte del siglo XX parecen asociadas al comienzo de este proceso. Paralelamente al proceso de decaimiento aparecieron numerosas alertas de plagas y patógenos que estaban afectando estos bosques. Los Pirineos han sido usados durante siglos por el hombre, la gestión y la dinámica de estos debe ser tenida en cuenta cuando se pretende i) entender si las condiciones ambientales, la gestión y la dinámica forestal están asociadas al presente decaimiento del abeto, haciendo hincapié en el papel que determinados patógenos como Viscum album, Armillaria, Heterobasidion annosum y Melampsorella caryophyllacearum podrían tener en el proceso, mediante ii) el estudio de su epidemiología y mediante la identificación de cual es la gestión asociada a su incidencia y severidad. Se midieron 29 parcelas escogidas al azar en abetales del Pirineo. En cada una de las parcelas se midieron los síntomas de decaimiento y la presencia de signos y síntomas de ataques de plagas y patógenos en todos los árboles vivos. Se midió también la presencia de Armillaria y H. annosum mediante el cultivo de cilindros de madera extraídos del interior del tronco. Se midió la presencia de patógenos y plagas en árboles muertos y tocones. Los árboles muertos y los tocones se usaron para estimar la composición de especies arbóreas que tenían las parcelas en el pasado. Se midieron 42 variables para describir los árboles, las condiciones ambientales y la gestión que se había practicado en las parcelas. Se recogieron muestras de Armillaria y H. annosum, se cultivaron y se identificaron mediante técnicas moleculares de análisis del ADN. En ciertos casos fue necesario usar modelos mixtos no lineales, debido a la falta de normalidad y a la correlación espacial de los datos. Un 15% y un 10% de los abetos del Pirineo fueron considerados defoliados y cloróticos, respectivamente. Los árboles del estrato dominante fueron aquellos que mostraron un mayor decaimiento. Ninguna característica de masa se vio asociada al decaimiento de los árboles. Se observó que el abeto había aumentado su área basimétrica en los últimos años, y que la de los pinos (Pinus sylvestris y P. uncinata) había disminuido. Las perdidas de área basimétrica del abeto se debieron en la mayoría de los casos a un aumento de área basimétrica del haya (Fagus sylvatica), este hecho se vio también asociado a la presencia de daños sobre la regeneración de abeto producidos por ungulados. La presencia de V. album se encontró asociada al decaimiento y a la mortalidad del abeto. En masas puras se vio que V. album se había dispersado fácilmente entre y dentro de los árboles, pero en masas mixtas esta dispersión se había visto significativamente reducida. H. abietinum fue identificado en los Pirineos y su severidad era mayor en aquellos bosques donde las cortas habían afectado a un mayor porcentaje de abeto respecto a otras especies forestales. La presencia de H. abietinum se vio asociada a la presencia de V. album y la mortalidad de abeto fue mayor donde ambos patógenos ocurrían juntos. La roya M. caryophyllacearum se vio asociada al decaimiento del abeto. Este hongo pareció ser común en los Pirineos, pero su severidad era más alta en aquellas masas con un sotobosque con un mayor porcentaje de plantas tolerantes a la sombra. A. cepistipes fue la especie del género Armillaria más frecuente en los abetales. A. ostoyae se observó más frecuentemente en masas situadas a mayor altitud, y en aquellas en las que el abeto estaba colonizando más rápidamente otros tipos de bosque.
El decaimiento del abeto es relativamente bajo en los Pirineos, afecta a los árboles dominantes
de la masa, lo que sugiere que podría tratarse de aquellos árboles dejados después de las cortas como árboles de semilla. V. album parece el patógeno con un papel más importante en el decaimiento del abeto. Su severidad podría estar asociada al aumento de temperatura registrado en los Pirineos, y podría haber estado favorecida por la presencia de H. abietinum. Armillaria parece tener un papel notable en la dinámica de los bosques de pino y abeto, y podría estar asociada al aumento de F. sylvatica observado en los abetales. M. caryophyllacearum parece encontrar mejores condiciones para infectar el abeto en masas cerradas que en masas abiertas. El aumento de la sequía registrado en el Pirineo parece que ha incitado el decaimiento en el Pirineo. La gestión en general ha favorecido al abeto, sin embargo podría haber predispuesto a determinados árboles a decaer. El aumento de la diversidad de especies así como una reducción de la competencia deberían examinarse como posibles técnicas para aumentar la salud de estas masas.
Silver fir (Abies alba) decline was reported in the 1990s in the Spanish Pyrenees without a clear
explanation of its occurrence. Climatic conditions of the last part of the 20th century seem associated with the onset of the decline. In parallel with the decline process numerous reports of high incidences of pest and pathogen appeared making necessary to understand the role of the biotic factors in this process. Pyrenean forests have been used for centuries by humans, the role of management and the dynamics of this forests should also be considered when aiming to i) elucidate whether the environmental conditions, the management and the forest dynamics are associated to the fir decline in the Spanish Pyrenees, paying special attention to the role of the critical pathogens Viscum album, Armillaria, Heterobasidion annosum and Melampsorella caryophyllacearum, by means of ii) studying their epidemiology and to identify the management practices that are associated to their incidence and severity. Twenty nine randomly selected stands were measured throughout the Pyrenees. In each stand all living trees were observed for symptoms of decline and for pathogen evidences. Armillaria and H. annosum incidence in living trees was also assessed by culturing inner wood cores. Stumps and dead trees were observed for the presence of pathogen signs, and were used for assessing the past species composition of present fir stands. Up to 42 variables were measured describing the trees characteristics and the environmental conditions and the management practised in the stands. Armillaria and H. annosum samples were collected, cultured and afterwards typed by molecular techniques. Hypotheses were often tested by means of non-linear mixed models due to the lack of normality and the spatial correlation of the data. Defoliation and chlorosis were observed in 15% and 10% of trees respectively. Decline symptoms appeared more often in the dominant layer trees. No stand variables seemed associated with the decline. Silver fir basal area increases were observed coupled with pines (Pinus sylvestris and P. uncinata) basal area losses. Fir losses were mostly due to beech (Fagus sylvatica) colonisations and correlated with ungulate browsing of fir seedlings. V. album correlated with both decline and mortality of fir. V. album was found spreading easily between and within trees in pure fir stands, whilst in mixed stands seemed to find significant difficulties of spread. H. abietinum was identified in the Pyrenees and its severity on stumps was higher where cuttings had focussed more in silver fir than in other tree species. H. abietinum presence related with V. album presence and the silver fir mortality was higher
where both species appeared together. M. caryophyllacearum was also found associated to fir decline. This rust fungus was frequent in Pyrenees and its severity appeared associated with the presence of shade tolerant plants in the understory of the stands. A. cepistipes was the most frequent Armillaria species in silver fir stands. A. ostoyae was more frequent in higher elevations and related to the increase of silver fir against other tree species. Silver fir decline incidence is relatively low and is more evident on dominant trees. Their characteristics suggest that they were those left after cuttings. V. album was the most likely pathogen implied in the decline of silver fir. Its severity could associate to the warming conditions of Pyrenees, and might be enhanced by the presence of H. abietinum in the stands. Armillaria seems to play a role in the dynamics of silver fir-pine forests. M. caryophyllacearum infection could find better infection chance in thick than in open stands. Aridity conditions of the second half of the 20th century seem to have incited the onset of decline. Management practices seem to have favoured silver fir in the Pyrenees, but also might have predisposed some trees to decline.
Altogether, either the promotion of mixed stands or the reduction of the competition could be
tested to improve the health of these forests.

The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old. Understanding regeneration patterns in the MH zone has become increasingly important as logging continues towards higher elevations of the zone where snowpacks are deeper.

Growth release of trees following canopy disturbances is of interest to ecological scientists and forest managers. Using dendroecological techniques, I examined growth release of canopy and subcanopy trees following the formation of natural, fine-scale canopy gaps in old-growth, western red cedar-western hemlock forests of coastal British Columbia. I aimed to quantify detailed information on release of the three shade-tolerant tree species that constitute these stands: western red cedar (Thuja plicata), western hemlock (Tsuga heterophylla), and Pacific silver fir (Abies amabilis). As a first step, I calibrated the radial-growth averaging method to account for regional-scale variability and capture a more complete range of growth releases that may occur following the formation of fine-scale gaps in the study stands. A 25% threshold, 5-year moving average, and 10-year window emerged as appropriate parameters for detecting releases using radial-growth averaging. Basal area increment was also the most appropriate growth index for detecting releases. Establishing these empirically-based criteria was important for quantifying the magnitude and duration of releases. Tree diameter and growth rate prior to release were the most important predictors of the magnitude and duration of releases, but identity of the tree species and distance from the gap center were also important predictors. Western hemlock and Pacific silver fir were often growing slowly both in the canopy and subcanopy, giving them tremendous potential to release. For these species, releases were generally intensive and persistent. In contrast, western red cedar were often growing quickly both in the canopy and subcanopy, giving them less potential to release. Compared to western hemlock and Pacific silver fir, western red cedar releases were less intensive and persistent. Patterns related to distance from the gap center emerged for trees growing along the north-south axis of gaps. Regardless of species, increasing distance from the gap center resulted in decreasing magnitude and duration of releases. However, patterns for duration were complex, as the distance effect was greater for trees north of the gap center. Information on growth release of trees is useful for reconstructing the history of past canopy disturbances, elucidating mechanisms of tree species coexistence, and assessing and predicting stand changes due to forest management in coastal British Columbia.

Site classification in the biogeoclimatic ecosystem classification system is based on three differentiating properties: climatic regimes (expressed by biogeoclimatic subzones or variants), soil moisture regimes (SMRs), and soil nutrient regimes (SNRs). A SNR represents a segment of a regional soil nutrient gradient, i.e., soils which provide similar levels of plant-available nutrients over a long period. SNRs are identified in the field using a number of easily observable soil morphological properties and indicator plant species. However, we need to know to what extent soil nutrient properties support these indirect field-estimates. There have been several studies that quantitatively characterize regional soil nutrient gradients in different climatic regions, but no study has yet been done in the subalpine coastal forest (Mountain Hemlock zone). Influenced by a maritime subalpine boreal climate, high-elevation coastal soils differ from low-elevation soils by having a thicker forest floor and a higher organic matter content. In the study summarized here, relationships between soil chemical properties and field-estimated SNRs are examined and soil chemical properties and field-identified SNRs are related to the site index of Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) - one of the major timber crop species in the Coastal Western Hemlock and Mountain Hemlock zones.

Une tendance à l’augmentation des dépérissements forestiers est observée et risque de s’accentuer dans le contexte actuel de changement climatique. La télédétection peut proposer des méthodes innovantes pour l’évaluation de l’état et du devenir des écosystèmes forestiers. Ce travail de thèse vise à proposer, valider et interpréter des mesures de baisse d’activité des résineux du Sud du Massif-Central et de la sapinière pyrénéenne. Le premier objectif est, par l’utilisation de séries temporelles d’images à moyenne résolution spatiale (images NDVI-MODIS), d’identifier les méthodes permettant de mesurer des baisses d’activité, et de vérifier qu’elles correspondent à des baisses de vitalité, dans des peuplements où se manifestent des phénomènes de dépérissement. La détection de changement d’activité, que l’on peut assimiler à des perturbations, repose sur deux approches : la première mesure des écarts ou des tendances de paramètres de phénologie de surface et la deuxième utilise une procédure de décomposition de la série temporelle. Les mesures de changement ont été réalisées sur la période 2000-2011. La détection des ruptures négatives et de forte amplitude dans la réponse de NDVI de 2003 à 2011 confirme l’influence de la sècheresse de 2003, qui se traduit à la fois par les baisses d’activité liées à l’état des arbres mais également par des coupes de dépérissement qui se sont succédées les années suivantes. Un travail préliminaire à l’étape de validation des baisses de vitalité détectées, a consisté à proposer et appliquer un modèle de détection des coupes afin d’éliminer ces situations des zones d’observation. Une procédure de validation des baisses de vitalité a été mise en place dans le cas de la sapinière des Pyrénées. Pour cela, deux approches ont été utilisées : (1) la confrontation à des données indirectes de l’état des peuplements mais spatialement exhaustives, à travers les inventaires des coupes de dépérissement sur la période 2000-2012 et une cartographie du dépérissement datant de 2001 et (2) la confrontation à des données d’observations directes de l’état des Sapins dans le Pays de Sault (Est des Pyrénées), en utilisant une méthode de diagnostic basée sur l’architecture des arbres (méthode ARCHI), avec un échantillonnage adapté à l’échelle des pixels MODIS (Lambert et al. 2013). Des relations ont été mises en évidence, permettant de valider les méthodes utilisées, mais aussi d’en ressortir des limites d’interprétation. Enfin, pour donner des éléments d’interprétation des phénomènes observés, les variations d’activité observées par télédétection ont été confrontées à des données climatiques et édaphiques spatialisées, adaptées à l’étude des milieux forestiers. Les résultats montrent que les baisses de vitalité constatées dans les peuplements de Sapins du Pays de Sault sont significativement corrélées au facteur climatique température et dans une moindre mesure, aux précipitations. Dans les Pyrénées Centrales, où les facteurs de causalité semblent être multiples, l’influence des conditions de sècheresse hydrique et édaphique n’a pas pu être démontrée
An increasing trend of forest decline is observed and is likely to increase in the current context of climate change. Remote sensing can provide innovative methods for the forest ecosystems status assessment. This thesis aims at proposing, validating and interpreting activity measurements of some Southern Massif Central and Pyrenees mountains coniferous stands. The first objective is, using of time series of medium spatial resolution (MODIS-NDVI) images, to identify methods to measure decreases of activity, and to verify if they correspond to vitality decreases in stands in which has been observed forest decline. Change detection of activity, which can be considered as disturbances, is based on two approaches: the first allows to measure differences or trends of phenology surface parameters, and the second uses a method based on the time series decomposition. Changes that occur during the 2000-2011 times-period were measured. The detection of high magnitude negative breakpoints in NDVI time series from 2003 to 2011 confirms the influence of the 2003 summer drought, which both led to decreases in activity related to trees heath status and also to clear-cuts during the following years. Before the validation process, a clear-cut detection method was proposed in order to eliminate these situations in the study areas. A validation procedure was implemented on Pyrenean fir stands. For this step, two approaches were implemented: (1) the use of spatially extensive state stands proxies, through cuts inventory inventories during the 2000-2012 times-period and a 2001 forest decline map, and (2) the use of data from direct tree heath’s observations in the fir stands of Pays de Sault region (Eastern Pyrenees) using a diagnostic method based on the observation of tree architecture (ARCHI method). For this second approach, an appropriate sampling was assessed to deal with the MODIS pixels scale (Lambert et al. 2013). Relationships have been identified, allowing to validate the used methods, but also to highlight theirs interpretation’s limits. Finally, to provide an interpretation of the observed phenomena, the remote sensing activity variations were compared to climatic and soil spatial data which are adapted to the study of forest environments. The results show that vitality declines in Pays de Sault fir stands are significantly correlated with climatic factors, temperature and to a lesser degree to precipitations. In the Central Pyrenees, where the causal factors appear to be numerous, the influence of water and soil drought conditions has not been demonstrated

The Mountain Hemlock (MH) zone includes all subalpine forests along British Columbia’s coast. It occurs at elevations where most precipitation falls as snow and the growing season is less than 4 months long. The zone includes the continuous forest of the forested subzones and the tree islands of the parkland subzones (Figure 1). Old-growth stands are populated by mountain hemlock, Pacific silver fir, and Alaska yellow-cedar, and are among the least-disturbed ecosystems in the world. Canopy trees grow slowly and are commonly older than 600 years, while some Alaska yellow-cedars may be up to 2000 years old. Early regeneration failures followed slashburning and the planting of unsuitable species. Currently, the most successful and feasible option for reforesting cutovers is natural regeneration with a mix of the three main tree species, but uncertainties remain about the temporal and spatial pattern of regeneration, changes in species composition, and the time required for stand establishment after cutting. Our study addressed these concerns by examining regeneration patterns on 6 sites that were clearcut 11-12 years prior to sampling and left to regenerate naturally. The sites were located at the lower limits of the zone in the Tetrahedron Range, near Sechelt, at elevations from 1060-1100m.

La crescita degli alberi è influenzata da molteplici fattori tra cui, il clima e i processi di competizione. I cambiamenti climatici hanno un forte impatto sulla crescita degli alberi e possono causare impatti negativi sulle foreste, soprattutto nel bacino del Mediterraneo. Tuttavia, la crescita degli alberi è influenzata anche dalle interazioni competitive. Per quantificare le interazioni competitive tra gli alberi vengono utilizzati indici di competizione, che normalmente sono calcolati su aree di piccole dimensioni. Prevedere le interazioni competitive su aree più estese può essere molto importante e i dati lidar (light detection and ranging) potrebbero essere lo strumento adatto. Sulla base di tali considerazioni, l’obiettivo principale della tesi è stato quello di individuare l’influenza delle variazioni climatiche e delle interazioni competitive sulla crescita di tre importanti specie forestali, faggio (Fagus sylvatica L.), abete rosso (Picea abies L.) e abete bianco (Abies alba Mill.). Il lavoro è strutturato in tre capitoli. Nel primo viene analizzata l’influenza del clima e degli eventi estremi sulla crescita del faggio e dell’abete bianco in plot misti e puri lungo un gradiente latitudinale in Italia. Nel secondo capitolo vengono analizzate le interazioni competitive in popolamenti misti e puri di faggio e abete bianco, situati ai limiti del loro areale di distribuzione (Italia meridionale). Nel terzo capitolo, invece, sono state stimate le dinamiche di competizione di abete bianco e abete rosso, situati nel comune di Lavarone (Trentino), e individuata la relazione tra le interazioni competitive e la biomassa degli alberi. Nel complesso, i risultati hanno evidenziato le risposte di accrescimento degli alberi alle variazioni climatiche e ai processi di competizione in foreste montane in Italia. In particolare, il primo lavoro ha evidenziato una risposta diversa solo a livello regionale per le temperature massime. In Trentino le temperature invernali, per l’abete bianco, ed estive, per entrambe le specie, hanno avuto un minor impatto negativo sulla crescita radiale degli alberi rispetto ai siti meridionali. Nonostante ciò, i risultati ottenuti dalle correlazioni (crescita radiale-indici di siccità) e dall’analisi delle componenti principali hanno evidenziato che nessun popolamento era sensibile alla siccità estiva. Nel secondo lavoro è stato osservato come l'incremento dell'area basimetrica, sotto l'influenza negativa di alti livelli di competizione e alta pendenza del terreno, variava tra i popolamenti. In tal senso sono state osservate interazioni competitive più elevate in Molise rispetto alla Calabria. Infine, nel terzo lavoro, è stato dimostrato che le metriche lidar possono essere utilizzate per prevedere gli indici di competizione. Inoltre, è stato osservato che la biomassa diminuiva all'aumentare della competizione. I risultati dei tre lavori hanno evidenziato che per la scelta di opzioni forestali sostenibili è necessario considerare le condizioni del sito in cui tali specie si trovano e la struttura dei popolamenti forestali, in termini di densità e disposizione degli alberi. Inoltre, è stato constatato che l’utilizzo di tecniche di telerilevamento (es. lidar) possono essere molto utili in campo forestale, poiché possono fornire informazioni su aree più estese.
Tree growth is influenced by multiple factors including, climate and competition processes. Climate change has a strong impact on growth of trees and can cause negative impacts on forests, especially in the Mediterranean basin. However, tree growth can also be influenced by competitive interactions, through the use and absorption of resources within tree communities. To quantify the level of competition between trees, competition indices are used, which are normally computed over small areas. Predicting competitive interactions over larger areas can be very important and light detection and ranging (lidar) data, could be the suitable tool. Based on these considerations, the main objective of the thesis was to identify and study the influence of climatic variations and competitive interactions on the growth of three important forest species, European beech (Fagus sylvatica L.), Norway spruce (Picea abies L.) and silver fir (Abies alba Mill.). The work is structured into three chapters, in which the first analyzes the influence of climate and extreme events on the radial growth of beech and silver fir in mixed and pure plots along a latitudinal gradient in Italy. In the second chapter the competitive interactions in mixed and pure populations of European beech and silver fir, located at the limits of their distribution range (southern Italy) are analyzed. In the third chapter, instead, was to estimate the competition dynamics for individual trees of Norway spruce and silver fir, located in the municipality of Lavarone (Trentino), and to identify the relationship between competitive interactions and tree aboveground biomass. Overall, results highlighted the response of trees under to climate and competition processes in mountain forests in Italy. In particular, the results of the first work showed a different response only at the regional level for the maximum temperatures. In Trentino the temperatures in winter, for silver fir, and summer, for both species, had a lesser negative impact on radial growth of trees compared to southern sites. Despite this, the results obtained from the correlations (radial growth-drought indices) and from principal component analysis have shown that no plot was sensitive to summer drought. Results are important to implement operational techniques that increase species adaptation to climate change. In the second work showed that the basal area increment, under the negative influence of high competition levels and slope terrains, varied between stands. In this sense, higher competitive interactions have been observed in Molise than in Calabria. Finally, in the third work showed that lidar metrics could be used to predict the competition indices of individual trees. In addition, biomass was observed to decrease as competition increased. The results of the three works showed that for the choice of sustainable forestry options it is necessary to consider the conditions of the site where these species are found and the structure of the forest stands, in terms of density and arrangement of the trees. Furthermore, it has been found that the use of remote sensing techniques (e.g. lidar) can be very useful in the forestry field, since they can provide information on larger areas.

Le changement climatique (CC) actuel, très rapide, va imposer aux espèces de faire évoluer leurs traits d’histoire de vie ou leur aire de répartition. En raison de leur long cycle reproductif, les arbres pourraient ne pas avoir la capacité à s’adapter suffisamment vite et leur aptitude à la migration devrait être déterminante. Les vitesses de colonisation des essences forestières lors de l'holocène ont fortement été revues à la baisse aux cours de la dernière décennie (quelques centaines contre quelques centaines de m/an). Dans ce contexte et en s'appuyant sur le sapin pectiné (Abies alba Mill.) en tant qu'espèce modèle nous avons étudié les principaux facteurs conditionnant l'aptitude à la migration. A partir de placettes de régénérations situées sur la face nord du Mont Ventoux, nous avons estimé la dispersion et le recrutement du sapin, en intégrant les sources de graines et les principales caractéristiques environnementales. La dispersion a également été estimée à partir de données génétiques. Dans les deux cas, les distances de dispersion sont de l’ordre du décamètre. La diversité génétique et l'évolution démographique ont été étudiées au sein de la régénération de sapins afin de tester l'hypothèse de purge de consanguinité. L'espèce présente en effet un régime de reproduction mixte, et la part d'autofécondation, à laquelle s'ajoute la reproduction entre individus consanguins, est à l’origine de l'excès d’homozygotie observé généralement dans la régénération, excès diminuant avec l’âge sous l’action d'une probable purge des individus les plus homozygotes. Les semis étudiés ne présentent pas un fort excès d’homozygotie, néanmoins, les individus les plus homozygotes meurent préférentiellement. Enfin, un modèle de dynamique forestière intégrant les processus, qui contrôlent la migration, a été implémenté afin d'évaluer la compatibilité entre la migration des espèces à long cycle de vie et le CC. Les premiers résultats de nos simulations indiquent que le sapin n’est pas capable de migrer aussi vite que s’opère le réchauffement
Current climate change (CC), really fast, will impose species to change their history life traits or their distribution range. Trees may not be able to adapt because of their long reproductive cycles hence their potentialities of migration is decisive. Past tree migration rates, during Holocene, were revised in downward these rates (several decameters against several hundred m/year). In this context, and focusing on silver fir (Abies alba Mill.) as “model species”, we studied main factors decisive for migration potentialities. Using regeneration plots, installed on Mont Ventoux north face, silver fir dispersal and seedling recruitment have been studied, including seed sources and main environmental characteristics. Dispersal was also estimated using genetic data. For both cases, dispersal distances are of the order of decameters. This species shows a mixed mating system, and auto-fertilization rate, plus reproduction between half-sibs, induces homozygosity excess, generally observed in regeneration, this excess decreases probably under the purge of inbred individuals. Our results show that seedlings do not have show homozygosity excess, however inbred seedlings die preferentially. Lastly, we constructed a model of forest dynamics that includes processes that determine migration, in order to evaluate the concordance between long life cycle species and CC. Our results show that silver fir does not migrate as fast as climate warming velocity

Les sous-produits qui proviennent de l’industrie du bois, particulièrement les nœuds, contiennent différents types de molécules qui peuvent être valorisées comme source de composants bioactifs pouvant répondre à des besoins thérapeutiques. C’est sur cette idée que le projet "Le Bois Santé" a été conçu. Grâce à la collaboration de plusieurs partenaires, le présent travail vise dans un premier temps à développer des procédés d’extraction "verts" (solide-liquide et supercritique) pour obtenir un extrait riche en lignanes à partir d’un mélange de nœuds d’épicéa commun et de sapin pectiné. Les effets des conditions opératoires sur le rendement d’extraction de chaque composé cible et sur l’activité anti-oxydante des extraits ont été déterminés. Afin d’étudier le procédé complet, le projet vise à étudier l’impact des procédés de concentration et de séchage de l’extrait à partir de l’évaporation sous vide et de la lyophilisation. De plus, la séparation et la purification des composés ont été développées et optimisées par simulation grâce à la technique de chromatographie frontale
By-products from wood industry, particularly knots, contain different types of molecules that can be valued as a source of bioactive components meeting therapeutic needs. It is on this idea that the project "Le Bois Santé" was designed. Through the collaboration of several partnerships, the present work aims initially to develop a "green" extraction processes (solid-liquid and supercritical) to obtain an extract rich in lignans from a mixture of norway spruce and silver fir knots. The effects of operating conditions on the extraction yield of each target compound and the antioxidant activity of the extracts were determined. To understand the entire process, the project aims to investigate the impact of concentration and drying processes using vacuum evaporation and lyophilisation. Moreover, the separation and purification of the compounds have been developed and optimized using frontal chromatography technique

De nombreux cas de mortalité de Sapin pectiné (Abies alba Mill.) sont constatés en limite sud de son aire de répartition en Provence et semblent être liés aux sécheresses successives de la dernière décennie et à la répartition des propriétés hydriques du sol. L'enjeu est alors de mieux évaluer l'impact du stress hydrique sur le fonctionnement écophysiologique de cette espèce et de pouvoir caractériser et cartographier les zones les plus vulnérables à la sécheresse. Sur le Mont Ventoux, une expérimentation a été mise en place pour suivre pendant 3 ans différents paramètres écophysiologiques impliqués dans le comportement hydrique du Sapin pectiné sur des placettes pour lesquelles les propriétés du sol étaient caractérisées. Sur cette montagne de type karstique, les profondeurs de sols sont très variables et, à l'échelle stationnelle, les taux de mortalité et les intensités de stress hydrique étaient plus élevés sur les sols ayant une réserve hydrique plus importante. De plus, un arrière-effet de la sécheresse de 2009 a été observé réduisant durablement la transpiration de l'année suivante. Une approche par modélisation mécaniste a alors été adoptée en intégrant de nouveaux formalismes sur la dynamique racinaire permettant de prendre en compte cet arrière-effet. Elle a été évaluée sur les différents paramètres impliqués dans le cycle de l'eau et du carbone des arbres et le modèle a été validé sur les dynamiques de transpiration et d'accroissement en largeur de cernes des troncs. Des indices basés sur la mesure de température de surface ont été utilisés pour évaluer la possibilité de détecter le stress hydrique en forêt. Il existe une variabilité résiduelle liée aux facteurs climatiques et à la dimension réduite de la surface de mesure dans la relation entre transpiration et température de surface à l'échelle de l'arbre. A l'échelle du versant, la température de surface a permis d'identifier la répartition spatiale de la durée et de l'intensité du stress hydrique en accord avec la typologie de sol réalisées. La télédétection dans l'infrarouge thermique pourrait ainsi être un outil intéressant pour la gestion forestière.

Direct Write (DW) defines an emerging group of technologies that allow the printing of electronic and other functional components out of vacuum, directly onto conformal surfaces. Both ink-jet and nozzle deposition technologies, which are seen to be complementary for the wide range of materials and processing required by industry, are employed in this project.Silver neodecanoate salt is sensitive to both light source, including ultra violet light (UV) and heat source, and is a good inkjet printing precursor when dissolved in xylene. We have studied the electrical properties of inkjet printed silver samples, derived from silver neodecanoate ink, and investigated the influence of UV treatment before thermal curing the silver samples. UV exposure at room temperature is believed to control the nucleation of silver particles. In addition we have studied the influence of thermal pre-treatment on the printed samples. This pre-treatment is thought to assist the neodecanoate precursor to form a uniform distribution of silver nanoparticles. The influence of UV exposure, thermal pre-treatment and the thermal curing conditions on subsequent track microstructure, and its influence on electrical resistivity is reported for glass substrates. Furthermore, a series of extruding experimental at different nozzle offset and pumping pressure settings are conducted based on the rheological property of silicone oil and silver paste to find the ideal condition for producing continuous tracks with good shape. These findings are used to simulate a computer model for further applications.

The telecommunication industry is dominating the world. Most recently there have been technological advancements made in mobile telecommunication. There are currently a few telecommunication organizations in South Africa. These organizations each have their own unique approach to service delivery. The strong competitive nature of the telecommunication industry is taking telecommunications in South Africa to greater heights. All these advancements necessitate the need for better security and controls of the telecommunications networks. RICA legislation was brought into effect to accomplish just this. The research focuses on the contingent use of systems development methodologies in the telecommunication industry in South Africa. The study determines how these telecommunication organizations choose a systems development methodology when developing systems. This study looks at how these organizations are currently implementing system development methodologies to keep up with the changes and competition within the industry. An interpretive approach was used to conduct the research. Four of the leading telecommunication organizations in South Africa were studied by using case studies. Each case study focused on a single telecommunication organization to gain in depth data regarding the use of systems development methodologies. The case studies were conducted by using structured interviews to gain data from multiple sources within the organizations. The data was analyzed using ATLAS.ti and a cross case analysis was done to answer the research questions. The results indicate that there is a contingent use of systems development methodologies within telecommunication organizations. The telecommunication organizations each use criteria to determine which systems development methodology to use. The results of the study indicate that there are different levels of contingency, and it examines how this is accomplished by each organization individually. Each of the organizations has a unique approach when selecting systems development methodologies. The systems development methodologies that are used by the telecommunication organizations are also tailored in some cases.
Thesis (M.Sc. (Computer Science))--North-West University, Potchefstroom Campus, 2011.

As sucatas eletrônicas são hoje consideradas como matéria prima de alto valor agregado e economicamente viável, devido à presença de metais preciosos (e.g. prata, ouro, platina e paládio) em sua composição. Em geral, a comercialização é baseada no teor de metais preciosos e cobre, sendo assim, as análises químicas desempenham papel fundamental nesse ambiente de negócios. O método mais empregado para esse tipo de análise, considerado padrão é o Fire Assay, que consiste na extração dos analitos da matriz tornando determinação final praticamente livre de interferências. Entretanto o Fire Assay é um método susceptível a erros sistemáticos devido ao grande número de etapas, lento, caro e ambientalmente insustentável devido à quantidade de reagentes utilizados e resíduos gerados (e.g. chumbo). Diante dessas importantes desvantagens, o desenvolvimento de métodos que apresentem exatidão, precisão, boa frequência analítica, custo e que gere poucos resíduos se tornam necessários para a melhoria do controle de qualidade desses materiais. Sendo assim, o objetivo dessa pesquisa foi o desenvolvimento de método para a determinação simultânea de Au, Ag e Pd por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES) e espectroscopia de fluorescência de raios-x por comprimento de ondas (WDSXRF), usando diferentes estratégias de preparação de amostras. As sucatas eletrônicas se caracterizam por serem heterogêneas, além disso, o material possui grande quantidade de metais como Al, Cu e Fe na composição fazendo com que a comunição seja um elemento chave no método e determinante da frequência analítica. Considerando esta dificuldade as amostras foram moídas em moinho oscilatório de discos de em diferentes tempos a fim de se investigar a influencia do tamanho de partículas para estudo de representatividade e precisão além da influencia do tamanho de partículas nas determinações por WDSXRF devido ao efeito sombra. Para os analises por WDSXRF as amostras com 40 minutos de moagem e preparadas com fusão com ferro e enxofre demonstraram boas correlações quando comprados ao Fire Assay. As dissoluções das amostras para analises em ICP OES ocorreu em duas etapas, a 1ª com HNO3 (aquecimento em chapa) para evitar passivação do ouro e a 2ª com 10 ml de água régia, usando o programa do forno de micro-ondas, com rampa de 160 °C a 210 °C (30 min). Foi observado que o excesso de Cl- formou complexos que inibiram perdas de Ag+ pro precipitação. As soluções finais foram analisadas no ICP OES e as concentrações obtidas foram comparadas ao método de Fire Assay. O método proposto mostrou boa correção para todos os elementos ao método padrão. A reprodutibilidade para Au foi de 4,1% (n=15 amostras) e a recuperação média comparada ao método padrão foi de 102%. Com base nos resultados obtidos pode-se dizer que o método proposto é comparável ao Fire Assay quanto à precisão e limites de detecção, apresentando melhores respostas quanto à frequência analítica, custo e geração de resíduos
Electronic scraps are today considered as raw material of high added value and economically viable, due to the presence of precious metals (e.g. silver, gold, platinum and palladium) in your composition. In general, the marketing is based on the content of precious metals and copper, therefore, chemical analysis plays a key role in this business environment. The method employed for this kind of analysis, considered standard, is the Fire Assay, which consists of the extraction of analytes in the array, making final determination virtually free of interference. However the Fire Assay is a method susceptible to systematic errors due to the large number of steps, slow, expensive and environmentally unsustainable due to the amount of reagents used and waste generated (e.g. lead). On these important disadvantages, the development of methods which have accuracy, precision, good analytical cost and frequency that generate few residues become necessary for the improvement of the quality control of these materials. Therefore, the objective of this research was the development of method for the simultaneous determination of Au, Ag and Pd by optical emission spectrometry with inductively coupled plasma (ICP OES) and fluorescence spectroscopy for x-ray wavelengths (WDSXRF), using different sampling strategies. Electronic scraps are characterized for being heterogeneous, in addition, the material possesses large amount of metals such as Al, Cu and Fe in the composition so that the communication is a key element in determining the frequency and analytical method. Considering this difficulty the samples were ground into oscillatory grinder discs at different times in order to investigate the influence of the particle size for study of representativeness and accuracy beyond the influence of the particle size determination by WDSXRF due to the shadow effect. For the analysis by WDSXRF samples with 40 minutes of grinding and prepared with merger with iron and sulfur showed good correlations when purchased the Fire Assay. The dissolutions of the samples for analysis in ICP-OES occurred in two steps, first with HNO3 (heating plate) to avoid gold passivation and the 2nd with 10 ml of aqua regia, by using the microwave oven, with 160 °C ramp to 210 °C (30 min). It was observed that the excess of Cl-formed complex that inhibit loss of Ag+ by precipitation. The final solutions were analysed at the ICP OES and the concentrations obtained were compared to the method of Fire Assay. The proposed method showed good fix for all elements to the standard method. Reproducibility for Au was 4.1% (n = 15 samples) and the average recovery compared to the standard method was 102%. Based on the results obtained can be said that the proposed method is comparable to the Fire Assay for accuracy and limits of detection, showing best answers regarding the analytical frequency, cost and waste generation.

This PhD thesis deals with the development of bioactive polysaccharide-based biomaterials for bone tissue and neural tissue engineering. Alginate was chosen for its gel forming properties; hyaluronic acid and chitlac (a lactose-modified chitosan) were chosen for their bioactive properties. The properties of these polysaccharides have been implemented by introducing gelatin, functionalized Carbon Nanotubes (f-CNTs) and silver nanoparticles (nAg). In the first part of the work, the dispersibility and aggregation tendency of f-CNTs have been characterized by means of Low Field Nuclear Magnetic Resonance (LF-NMR). It was also possible to correlate the f-CNTs concentration to the proton transversal relaxation rate of water. Alginate/f-CNTs solutions and hydrogels have been analyzed by LF-NMR, rheology and uniaxial compression tests; these investigations showed that the f-CNTs are able to affect nanocomposite properties depending on their concentration and functionalization. In the second part of the work, the preparation of a bioactive (bridging) implant for the treatment of Spinal Cord Injury is described. Neuronal cells and mesoangioblasts (MABs) engineered for the production of neurotrophines have been cultured and co-cultured on polysaccharide-coated glass substrates in order to evaluate the biological effects of chitlac. Chitlac-coated surfaces where shown to possess higher surface energies if compared to chitosan-coated ones and enable the formation of wider neural networks with improved electrical activity. The co-cultures confirmed the higher bioactivity of chitlac/alginate substrates and the biological role of neurotrophines. Porous scaffolds of alginate/chitlac have been prepared; these scaffolds where shown to be stable in simulated body fluid for over a month. The mechanical properties of rehydrated scaffolds where proved to be similar to those of neural tissue. Biological properties of chitlac substrates enriched with f-CNTs are currently under investigation. In the third part of the work, tridimensional scaffolds and injectable fillers were developed for the treatment of non-critical bone defects. Porous scaffolds with different pore morphologies have been prepared by freeze casting of alginate/HAp hydrogels. Isotropic porosity was obtained by freezing the constructs in a cryostat, while anisotropic porosity was obtained by the Ice Segregation Induced Self Assembly process. Physical, mechanical and biological analyses revealed that the differences in pore morphology determine differences in the mechanical properties of the scaffolds. Biocompatible f-CNTs have been used to implement the isotropic scaffolds; the biological analyses showed that the presence of f-CNTs does not affect scaffold properties. Osteoconductive/antimicrobial injectable bone fillers, based on alginate/HAp microbeads dispersed in polysaccharide mixtures, have been developed. Microbeads were enriched with nAg synthesized in chitlac. Antimicrobial assays proved the antibacterial properties of the microbeads towards bacteria in suspension and on pre-formed biofilms. Biological assays showed the biocompatibility of the microbeads and their ability to sustain osteoblast proliferation. The fillers prepared by dispersing microbeads in polysaccharide mixtures were shown to be easily injectable through surgical syringes. In vivo studies on a rabbit model of non-critical bone defect pointed out the biocompatibility and the osteoconductivity of the composite materials. Further studies are ongoing in order to evaluate the possibility to further implement the bioactive properties of the microbeads by addiction of gelatin.

Utilisation of silver nanoparticle paste as high temperature die attach has been investigated. The examinations of high temperature behaviour of sintered silver have indicated massive grain growth and microstructural evolution at 250 °C. The rate of evolution of the microstructure has been found to increase substantially above 350 °C. This high temperature behaviour can undermine the reliability of sintered silver nanoparticles at high operating temperatures if no modifications are applied to the pure form of this material. In addition to the microstructural evolution of the silver in isolation, silver atoms inside the die attach undergo massive migration towards any gold interfaces contacting the die attach. This behaviour can result in reduction of the mechanical performance of the die attach and undermine the thermal reliability as well. Here two new techniques are introduced addressing these two concerns, both of which produce joint structures with improved thermal stabilities. In one technique oxidation of sintered silver’s internal surfaces has been able to stop microstructural evolution of sintered silver up to 400 °C, increasing the thermal stability of sintered silver from 200 °C to this new limit. The other technique has combined sintered silver with a gold mesh interposer to use the mass migration of silver and gold atoms to obtain extreme thermal stability. The samples produced with this technique could withstand testing at 600 °C. Furthermore, a review of literature on this field has uncovered the result that while applying sintering pressure on the die results in improved mechanical strength, without this pressure the higher porosity allows better thermal cycling resistance of sintered silver. This indicates another important advantage of the second thermal stabilization technique, namely that using a mesh interposer allows control over the amount of porosity, helping to achieve the desired properties.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais
Industrial process have been historically an important factor of environmental degradation. The disposal of industrial wastes, mainly containing toxic metals, in water sources represents a problem of great concern not only in relation to biota in receiving environment but also to humans. In this work, the adsorptive capacity of the crushed seeds of Moringa oleifera Lam. was evaluated in order to quest alternative materials for removal and preconcentration of silver ions. The first chapter describes the results of removal of Ag(I) ions in contaminated aqueous systems utilizing moringa seeds. Preliminary tests were carried out using the seeds of moringa as: non-shelled, shelled seeds and husks were tested for their adsorption potential for ions Ag(I). The results showed greater efficiency for non-shelled seeds. The parameters evaluated were: particle size, pH and agitation time, concentration and volume of solution, adsorbent mass. Silver was quantified before and after treatment, by Flame Atomic Absorption Spectrometry. The optimum conditions were: particle size ≤ 500 μm, pH = 6.5, agitation time = 20 minutes, adsorbente mass = 2.0 g, concentration of Ag(I) = 25 mg L-1 and volume = 100 mL. In these conditions, the removal of ions Ag(I) was 98%. The proposed methodology was applied to the treatment of the following samples: residue of experimental classes of Analytical Chemistry and analysis of chemical oxygen demand, generated at the university, and waste photographic material from local industries. The values obtained for the removal of Ag(I) were 92%, 82% and 91% respectively, using the non-shelled seeds of moringa as adsorbent. Also, it was studied the possible interference of other metals in proposed method, namely Cd(II), Co(II), Cu(II) e Pb(II). The value of the maximum adsorptive capacity for ions Ag(I) was 25.56 mg g-1 obtained through of the adsorption isotherm. Characterization techniques, including infrared spectrometry, X-ray diffraction, thermogravimetric analysis and scanning electron microscopy were used to assess physical and chemical proprieties of nonshelled seeds of moringa. The second chapter was presented a method for preconcentration of v ions using flow system and non-shelled seeds of Moringa oleifera Lam. as adsorbent material. The preconcentration system was coupled to FAAS. The following experimental conditions carried out: for 4 minutes leachate solution of Ag(I) 0.01 mg L-1, about of ground seeds of moringa packaged in a mini-column flow of. The elution was performed with of HNO3 0.5 mol L-1. The concentration factor was 35, resulting in detection limit of 0.22 μgL-1 e quantification limit of 0.73 μgL-1. Accuracy of the method was cheked by using certified reference material for water APS-1071 (Alpha Resources 3090 Johnson RD, Stevensville, USA). The proposed method has advantages such as low cost of sorbent, high efficiency and minimization of chemical sludge. The moringa is an alternative material for chemical remediation and is economically and environmentally friendly.
Processos industriais tem sido historicamente um importante fator de degradação ambiental. A disposição inadequada de resíduos industriais contendo metais tóxicos em fontes de águas representa um grande problema, que concerne não somente à biota, mas também para humanos. Neste trabalho, foi avaliada a capacidade adsortiva das sementes trituradas de Moringa oleifera Lam. como um material alternativo para remoção e pré-concentração de íons Ag(I) em águas. No primeiro capítulo foi avaliada a capacidade das sementes de moringa para remoção de íons Ag(I) em sistemas aquosos contaminados por este íon metálico. Antes da otimização dos parâmetros foram realizados testes preliminares com a moringa envolvendo a casca da semente, polpa da semente e a semente integral para avaliar a parte da semente que apresentava maior capacidade de remoção, e como espécie analítica de interesse, utilizou-se íons Ag(I). Os resultados mostram maior eficiência usando as sementes integrais. Os parâmetros de otimização avaliados para o adsorvente nos ensaios de remoção foram: granulometria, pH e tempo de agitação, volume de solução, concentração e massa do adsorvente. A quantificação do teor de prata, antes e após o tratamento, foi realizada por Espectrometria de Absorção Atômica por Chama (FAAS). As condições otimizadas foram: Granulometria ≤ 500 μm; pH = 6,5; Tempo de Agitação = 20 minutos; Massa = 2,0 g; concentração de Ag(I) = 25 mg L-1 e volume = 100 mL. Observou-se uma remoção de íons Ag(I) de 98% quando se utiliza a Moringa oleifera Lam. como adsorvente. A metodologia proposta foi aplicada para o tratamento das seguintes amostras: resíduo de aulas práticas de Química Analítica e de análise de DQO, gerados nesta Instituição de Ensino; de material fotorrevelador e resíduo de material gráfico, ambos obtidos em indústrias locais. Os valores obtidos para a remoção de Ag(I) foram de 92%, 82% e 91% respectivamente, utilizando as sementes trituradas de moringa como adsorvente, sendo que para o resíduo do material gráfico não foi detectado a presença do metal de interesse. Foi estudada a possível interferência de outros metais nesta análise, a saber: Cd(II), Co(II), Cu(II) e Pb(II). O valor da capacidade máxima adsortiva (CMA) de íons Ag(I) pelo adsorvente 25,56 mg g-1 de semente de moringa seca, foi obtido com a construção da isoterma de adsorção, determinando-se graficamente a quantidade máxima (mg) do adsorvato que pode ser adsorvido numa dada massa de adsorvente (g). Técnicas de caracterização incluindo espectrometria por infravermelho, difração de raios-X, análise termogravimétrica e microscopia eletrônica de varredura foram utilizadas na avaliação físico-química das sementes trituradas de moringa. No segundo capítulo foi apresentado um método de pré-concentração de íons Ag(I) utilizando análise em fluxo com o emprego de sementes trituradas de Moringa oleifera Lam., como material adsorvente. O sistema de pré-concentração acoplado ao FAAS foi executado com o referido adsorvente percolando durante 4 minutos solução de Ag(I) 0,01 mg L-1, na mini-coluna recheada com 35 mg de sementes trituradas de moringa a uma vazão de 5,5 mL min-1. A eluição foi realizada com 100 μL de HNO3 0,5 mol L-1. Foi obtido um fator de préconcentração igual a 35; limite de detecção (LD) igual a 0,22 mg L-1 e limite de quantificação (LQ) igual a 0,73 mg L-1. A exatidão do método foi atestada com o uso de padrão certificado para águas APS-1071 (Alpha Resources 3090 Johnson RD, Stevensville, USA). Diante dos resultados obtidos, conclui-se que o material apresentou alta capacidade de remoção para íons Ag(I). O método desenvolvido mostrou-se satisfatório para a pré-concentração e determinação de íons prata em águas dada a sua simplicidade, eficiência, baixo custo e pouca influência dos contaminantes estudados. Avalia-se que a utilização da Moringa oleifera Lam. como material alternativo para a pré-concentração de prata é viável.
Doutor em Química

Questo lavoro centrato sull'analisi dell'auto-assemblaggio di eliche biologiche, in particolare frammenti di DNA con diverse lunghezze e strutture di Guanosina 5'-monofosfato(G-quadruplessi) in presenza di alcuni ioni, in questo caso argento e litio. I DNA corti sono molto attrattivi per le loro applicazioni nel drug delivery e per il DNA origami come possibile modello per nanomacchine e materiali 3D intelligenti. Il G-quadruplesso rappresenta l'organizzazione supramolecolare dei G-quartetti, anelli planari costituiti da quattro GMP legate tramite legame idrogeno di Hoogsteen. Le tetradi di GMP si impilano una sull'altra e l'impilamento è stabilizzato dalla presenza di cationi monovalenti (Na+,K+, ecc). I G-quadruplessi sono interessanti poichè sequenze ricche di G si possono trovare nei telomeri (la regione a singolo filamento all'estremità dei cromosomi). La formazione dei G-quadruplessi comporta una generale riduzione nell'estensione dei primer da parte della telomerasi; questo enzima che estende le sequenze telomeriche nei cromosomi è espresso ad alti livelli nelle cellule tumorali permettendo loro di replicarsi indefinitamente portando all'immortalizzazione che conduce al processo di carcinogenesi. Quindi l'interesse per i G-quadruplessi è legato alla loro possibile attivitti-cancro. Dall'altro lato i G-quadruplessi possono essere usati per la nanoelettonica. Infatti sono stati proposti come basi per nanofilamenti molecolari poichè l'elevata rigidità strutturale e stabilità in varie condizioni, aumenta la migrazione di cariche attrverso il G-filamento. In questa tesi viene presentata l'analisi su DNA e G-quadruplessi tramite esperimenti di scattering a piccolo angolo di raggi X e neutroni (SAXS e SANS), diffrazione di raggi X e neutroni (XRD e ND) e microscopia ottica a luce polarizzata. In particolare per i G-quadruplessi è stata evidenziata la formazione della fase LC smettica, diversa dalle fasi esagonale e colesterica solitamente trovate.
This work is focused on the analysis of the self-assembly mechanism of biological helices, in particular DNA fragments with dfferent length and Guanosine 5- monophosphate struc- tures (G-quadruplex) in presence of some ions, in this case Silver and Lithium. Short DNA are very attractive for their possible applications in drug delivery and for the DNA origami used as possible template for nanomachine and 3D smart materials. Instead G- quadruplex is the supramolecular organization of G-quartets, planar rings constituted by four GMP linked by Hoogsteen hydrogen bonds. The GMP tetrads stack one on the top of another and the stacking is stabilized by the presence of monovalent cation (Na+, K+, etc). G-quadruplexes are interesting because G-rich sequences can be found in telom- eres (the single-stranded DNA regions at the end of chromosomes). The formation of G-quadruplexes involves a generally reduction of the effiency of primer extension by telomerase; this enzyme extends the telomeric sequences in chromosome and it is expressed in high level in cancer cells allowing them to replicate indefinitely and bringing to an immortalization condition that leads to the carcinogenesis process. Therefore the interest in G-Quadruplexes is linked with the several hypotheses on possible anti-cancer activities. On the other side G-quadruplex can be used for nanoelectronics. They were in fact proposed as building blocks of molecular nanowires because the higher structural rigidity and stability under various conditions, increasing the probability of charge mi- gration through the G-wires. In this thesis, it is presented an analysis on the DNA and G-quadruplex structures by Small Angle X-Ray and Neutron Scattering (SAXS and SANS), X-Ray and Neutron Dffraction (XRD and ND) and Polarized Optical Microscopy experiments. In particular for the G-quadruplex it is highlight the formation of a smectic LC phase, dfferent from the usually found hexagonal and cholesteric phase.

L'etude presentee dans ce memoire s'inscrit dans le cadre de la comprehension de la variation thermique de la magnetoresistance geante de multicouches argent/nickel-fer couplees antiferromagnetiquement, qui sont dans la course aux applications comme capteurs de champ magnetique. Par des mesures d'aimantation, de diffraction de rayons x et de spectroscopie mossbauer, nous avons suivi de facon tres precise les evolutions thermiques des proprietes magnetiques et structurales et nous avons pu expliquer celle des proprietes magnetoresistives. La magnetoresistance geante presente un maximum pour une temperature de recuit voisine de 250c : ceci resulte d'une part de l'augmentation de la temperature de curie, et d'autre part de l'amelioration des interfaces qui intervient du fait de l'immiscibilite entre l'argent et le nickel-fer. Au-dela de cette temperature de recuit, la magnetoresistance geante decroit fortement jusqu'a 320c, alors que le lissage des interfaces se poursuit jusqu'a cette meme temperature. En fait, entre 250c et 320c, des ponts ferromagnetiques apparaissent ; ils sont alors en nombre suffisant pour detruire la magnetoresistance geante et donner lieu a une contribution remanente en aimantation, mais trop peu nombreux pour perturber la qualite moyenne de la multicouche (dont les interfaces continuent de s'ameliorer). Pour des recuits a plus hautes temperatures, la multicouche est detruite : c'est la destratification. L'application d'un champ magnetique exterieur pendant les traitements thermiques provoque une acceleration de l'evolution thermique de la multicouche. Ainsi, le couplage antiferromagnetique, present en champ nul, stabilise la multicouche tant du point de vue de ses proprietes magnetiques que structurales.

O Rio da Prata foi uma região estratégica aos interesses políticos e econômicos de todos os países ao sul do continente americano. As disputas por seu controle e navegabilidade estiveram em pauta nos embates entre projetos de nação nos Estados em formação naquele momento e, em muitas oportunidades, transpuseram o limite das ideias e negociações e chegaram ao campo de batalha, onde tais países puseram-se frente a frente na defesa de interesses distintos, tanto pela consolidação de suas relações externas quanto pela estabilidade política interna. Nesse sentido, a presente dissertação pretende analisar de que maneira o Brasil criou condições para levar a cabo seus projetos políticos e econômicos no Rio da Prata, entre 1842 e 1852. Tomando por base a atuação política e militar de Luis Alves de Lima e Silva barão, conde, marquês e futuro duque de Caxias nesse período, busca-se compreendê-lo como uma figura central e um importante representante e artífice dos interesses políticos brasileiros no contexto platino, desde a sua missão de pacificação da conhecida Revolução Farroupilha, passando por seus primeiros anos como senador do Império (pelo Rio Grande do Sul), até regressar ao campo de batalha, nas campanhas que derrubaram do poder Manuel Oribe, na República Oriental do Uruguai, e Juan Manuel de Rosas, na província argentina de Buenos Aires, durante a intervenção brasileira na Guerra Grande.
The River Plate was a strategic region to the political and economic interests of all the southern countries of the American continent. The disputes for its control and seaworthiness were in focus on the conflicts between nation projects in the states in formation at that moment, and in many occasions, they transposed the limit of the ideas and negotiations and reached the battlefield, where such countries settled face to face to defend different interests, for consolidation of its external relationship and internal political stability. Therefore, this dissertation intends to analyze the method Brazil used to create conditions to execute its political and economic projects on the River Plate between 1842 and 1852. Based on the political and military performance of Luis Alves de Lima e Silva - Baron, Count, Marquis and future Duke of Caxias at that period, it\'s intended to see him as a main character and an important representative and creator of the Brazilian political interests in the River Plate region context, since his pacification mission of the well-known Ragamuffin War, through his first years as the Empire senator (representing Rio Grande do Sul), until his return to the battlefield, in the campaigns that took Manuel Oribe off the power, in the Eastern Republic of Uruguay, and Juan Manuel de Rosas, in the argentine province of Buenos Aires, during the Brazilian intervention in the Uruguayan Civil War.

L'industrie lithique du Néolithique final provençal demeure relativement insaisissable si elle est n'est abordée que d'un point de vue technique et selon une typologie établie à partir d'observations effectuées à l'oeil nu. Ses caractéristiques, c'est-à-dire une dichotomie représentée par des productions laminaires standardisées issues d'ateliers spécialisés, et une production domestique techniquement peu investie dont la finalité n'est pas évidente à déterminer, nécessitent que l'on augmente l'échelle des observations des objets de silex. Ces dernières, alors d'ordre pétrographiques et tracéologiques, permettent de reconstituer les chaînes opératoires avec davantage de fiabilité, et d'identifier les outils qu'elles visent à produire. lI est alors possible de proposer une typologie plus adaptée à partir de l'ensemble de l'outillage et de percevoir les normes existantes. La comparaison des données issues de trois sites complémentaires permet d'illustrer les avantages de la méthode d'étude développée dans ce travail de doctorat et de proposer une ébauche de caractérisation des industries lithiques de cette période
The lithic industry from the Late Neolithic of Provence stays quite imperceptible if studied by a classic technique and typology approach. Its caracteristics, a dichotomy represented by standardized long blade productions coming from specialized workshops on one hand, and a technically simplified domestic production of wich standards aren't easy to find on the other, need a higher resolution improvement in the observations that are made. Those ones, then of a petrographical and traceological nature, allow a better understanding of the operating chains as well as to identify the tools they are destinated to produce. It then is possible to propose a more adapted typology and to show the existing standards. The comparison of the lithic industries of three complementary occupations illustrates the advantages of the methodology developped in this work and suggests, at last, a sketch of the caracteristics of the lithic industry from this period

Este ensaio clínico randomizado, cego e controlado com placebo teve como objetivo principal avaliar a eficácia do diamino fluoreto de prata (DFP) a 30% no tratamento não operatório de lesões de cárie em superfícies proximais de molares decíduos e compará-la a eficácia do infiltrante resinoso e a do controle do biofilme interproximal pelo uso do fio dental. Além disso, também avaliou a custo-eficácia e o desconforto dos tratamentos e a satisfação dos participantes quanto ao tratamento recebido. Para isso, foram selecionadas 141 crianças entre 3 e 10 anos de idade, que apresentavam pelo menos uma superfície proximal com lesão de cárie clinicamente em esmalte. A alocação dos participantes foi aleatória, de acordo com o tratamento: DFP a 30%, infiltrante resinoso de cárie e orientação para o uso diário do fio dental (controle). Todos os participantes receberam o tratamento ativo para os quais foram alocados e também o placebo dos tratamentos realizados nos outros grupos. Os custos dos materiais utilizados nos tratamentos foram registrados. Ao final da consulta de tratamento, foi aplicada aos participantes a Escala Facial de Wong-Baker para avaliação do desconforto. Os responsáveis pelos participantes, que concluíram o seguimento da pesquisa, responderam a um questionário de satisfação sobre o tratamento recebido. As crianças foram examinadas após 1 mês para avaliação de higiene bucal e também de presença de biofilme nas superfícies tratadas. Após 6, 12 e 24 meses, foram realizados exames visual e tátil para verificar a progressão das lesões tratadas, além de exame radiográfico aos 12 e 24 meses. Para avaliar a eficácia dos tratamentos, consideraram-se como desfechos: (I) qualquer progressão clínica da lesão tratada e (II) progressão para cavidade em dentina. A progressão radiográfica foi utilizada como um desfecho secundário e para comparar com o padrão clínico de progressão das lesões. Análises de regressão foram realizadas para verificar se os grupos de tratamento influenciaram os desfechos testados após 12 e 24 meses de seguimento (análise por protocolo - Poisson multinível e análise de sobrevida). Valores pontuais de custo-eficácia dos tratamentos foram calculados e, para comparar a custo-eficácia da implementação do uso do DFP em relação às outras opções testadas foi utilizada a razão de custo-eficácia incremental. Análises de regressão de Poisson foram utilizadas para verificar a associação entre o desconforto e variáveis explicativas. A satisfação dos participantes e seus responsáveis foi explorada descritivamente. Um total de 316 superfícies proximais foram incluídas, sendo a maioria classificada como escore 2 do ICDAS (Sistema Internacional de Detecção e Avaliação de Cárie) associadas à ausência de imagem radiográfica (46,8%). As perdas de seguimento foram de 15% e 24% aos 12 e 24 meses, respectivamente. Não houve associação entre o grupo de tratamento e a progressão das lesões aos 12 e 24 meses, tanta pela análise por protocolo como pela análise de sobrevida. A taxa de progressão clínica das lesões para cavidade em dentina foi de 2,5% aos 12 meses e de 5,6% aos 24 meses. As lesões que não apresentavam imagem radiográfica inicial não progrediram para o 1/3 médio de dentina ou mais. A condição clínica inicial das lesões foi associada à progressão das lesões em todas as análises. Já o risco de cárie foi associado à progressão das lesões aos 24 meses e também na análise de sobrevida. O tratamento com infiltrante resinoso apresentou o custo mais elevado, fazendo com que o tratamento com DFP apresentasse melhor relação custo-eficácia do que este primeiro. Os participantes tratados com o DFP e os que receberam orientação para o uso do fio dental relataram menor desconforto do que os tratados com o infiltrante resinoso. Os responsáveis se mostraram satisfeitos com o tratamento recebido, independentemente do grupo ao qual foram alocados. Conclui-se que o tratamento com DFP é tão eficaz quanto o infiltrante resinoso e a orientação para o uso do fio dental no controle das lesões iniciais em proximal de molares decíduos. No entanto, causa menor desconforto e apresenta custo-eficácia superior ao infiltrante resinoso, devendo ser preferível para superfícies proximais de molares decíduos, em situações nas quais o tratamento dessas lesões possa ser necessário, como por exemplo, pacientes com experiência de cárie.
This randomized, blinded and placebo-controlled clinical trial aimed to evaluate the efficacy of 30% silver diamine fluoride (SDF) as a non-operative treatment of the approximal surfaces of primary molars and to compare it with the efficacy of resin infiltration and the mechanical control of the interproximal biofilm by flossing. We also evaluated the cost-efficacy and the discomfort of the treatments as well as the parent\'s satisfaction regarding treatments. One hundred forty-one, 3-to-10-year-old, children were included. They must present at least one caries lesion clinically into enamel sited on an approximal surface of primary molar. Participants were randomly allocated to the following groups according to active treatment to be received: 30% SDF, caries resin infiltration, flossing orientation (control). All participants received the active treatment, in which they were allocated and they also received the placebo treatment corresponding to the other groups. Costs of materials used in the treatment were registered. In the end of treatment session, the Wong-Baker faces scale was applied to evaluate participants\' reported discomfort. Children were examined after 1 month to evaluation of the oral hygiene and the presence of the biofilm on the treated surfaces. After 6, 12 and 24 months, visual and tactile examinations were performed to verify the lesions progression. Radiography was taken at 12- and 24-month follow-ups. To evaluate the efficacy of non-operative treatments, two outcomes were considered: (I) any clinical progression and (II) progression to cavity into dentine. The radiographic progression was used as a secondary outcome and to evaluate with clinical standard of lesions progression. Regression analyses were used to verify if the treatment influenced on these outcomes after 12 and 24 months (per-protocol analyses - multilevel Poisson and survival analysis). Cost-efficacy ratios were calculated for the treatments. To compare the cost-efficacy of implementing the use of DFP versus other options tested, the incremental cost-efficacy ratio was used. Poisson regression analyses were used to verify the association between discomfort and explanatory variables. The parents\' satisfaction about the treatments were explored descriptively. A total of 316 approximal surfaces were included. The majority of them were classified as ICDAS (International Caries Detection and Assessment System) score 2 associated with absence of radiographic image. The dropout in the study was 15% and 24% at 12-month and 24-month follow-up, respectively. There was no association between treatment groups and lesions progression at 12 and 24 months, both for the per-protocol analysis and by survival analysis. The rate of clinical lesions progression to cavity into dentine was 2.5% at 12 months and 5.6% at 24 months. Lesions without initial radiographic image did not progress into the middle of the dentine or more. Baseline clinical condition of caries lesions was associated with lesions progression in all analyses. The caries risk was also associated to caries progression in 24-month analyses and in the survival analyses. The treatment with resin infiltration was costlier. Consequently, the treatment with SDF was more cost-effective than resin infiltration. The participants allocated to SDF and control groups reported less discomfort than those who was allocated to the resin infitrant group. The parents were satisfied with the treatment received during the study, independently of the group to which their children had been allocated. It is possible to conclude that the SDF is as efficacious as the resin infiltration and flossing orientation to control initial lesions in the approximal surfaces of primary molars. However, SDF causes less discomfort and presents superior cost-efficacy relationship than resin infiltration and could be preferable to treat approximal caries in primary molars in those situations in which the treatment could be necessary, for example, depending on patients\' caries experience.

L’acquisition de ressources lithiques constitue un aspect fondamental de l’économie des communautés préhistoriques. L’étude de leur circulation représente dès lors une opportunité unique pour les archéologues d’appréhender les stratégies de gestion des industries lithiques. Dans ce cadre, les profondes transformations qui affectent les sociétés agropastorales du continent au cours de la seconde moitié du 5e millénaire voient l’émergence de nombreux sites spécialisés dans l’extraction de silicites, dont l’activité perdurera jusqu’à la fin du 3e millénaire. La région de Mons (Hainaut, Belgique) est une zone au sein de laquelle près d’une dizaine de sites d’extractions constituent le complexe minier du Bassin de Mons, dont le site emblématique est celui des mines de silex de Spiennes. Ce travail vise à caractériser les matières premières issues de ces sites miniers de même que leurs productions, afin d’appréhender la circulation des artefacts « miniers », de déterminer les stratégies d’acquisition des communautés agropastorales environnante selon une approche diachronique et enfin mettre en évidence les relations que les sites d’extraction entretiennent entre eux. Une dichotomie forte apparait entre les sites miniers d’importance régionale et les sites étant le lieu de productions normalisées et spécialisées. Ces derniers, d’importance extrarégionale, sont partiellement organisés entre eux et constituent un élément structurel de l’économie lithique dont le développement s’inscrit dans le cadre d’une hausse de la pression démographique et de l’occupation de nouveaux territoires
The acquisition of lithic resources is a fundamental aspect of the economy of prehistoric communities. The study of their circulation therefore represents a unique opportunity for archaeologists to understand the supply strategies of lithic industries. In this context, the major transformations affecting the continent's agro-pastoral societies during the second half of the 5th millennium have led to the emergence of many sites specialising in the extraction of silicites, whose activity will continue until the end of the 3rd millennium. The Mons region (Hainaut, Belgium) is an area in which nearly ten mining sites constitute the mining complex of the Bassin de Mons, whose emblematic site is the Spiennes flint mining site. This work aims to characterize the raw materials from these mining sites as well as their production, in order to apprehend the circulation of "mining" artifacts, to determine the acquisition strategies of surrounding agropastoral communities according to a diachronic approach and finally to highlight the relationships that mining sites maintain between them. A strong dichotomy appears between mining sites of regional importance and sites that are the place of standardized and specialized production. The later are of extra-regional importance, partially organized among themselves and constitute a structural element of the lithic economy whose development is part of an increasing demographic pressure and the occupation of new territories

Les nanoparticules (NPs) bimétalliques présentent des propriétés catalytiques très intéressantes qui justifient leur utilisation dans des procédés industriels de catalyse hétérogène. Leur structure (chimique, géométrique, électronique) est néanmoins susceptible d’évoluer dans des conditions environnementales réelles et modifier leurs propriétés. L’objectif de cette thèse pluridisciplinaire est de suivre la réactivité de ces NPs en atmosphère réactive contrôlée. Pour cela, on a développé un dispositif de spectroscopie in situ à modulation spatiale afin de suivre l’évolution de la structure sur une grande population de NPs via l’étude de leur résonance du plasmon de surface (RPS) localisée. Ces observations ont été couplées avec une approche locale (NPs individuelles) par microscopie électronique à transmission environnemental (MET-E). La MET-E a permis de révéler des effets de composition et d’environnement sur la structure chimique de NPs Ag-In. Des alliages stables pauvres en indium se forment, puis une coquille d’oxyde d’indium dont l’épaisseur augmente avec la concentration atomique d’indium. D’autre part, des domaines de structures stables (coeur@coquille, Janus, système réduit) ont été mis en évidence selon les conditions locales de température et de pression d’hydrogène. Enfin, l’oxydo-réduction de NPs Ag-Fe a été suivie in situ via l’étude de leur RPS. La MET, la plasmonique environnementale et les nombreuses simulations (réponse optique, simulations Monte-Carlo) suggèrent une ségrégation du fer et de l’argent avec une surface enrichie en argent. L’oxydation semble induire la diffusion du fer en surface, directement suivie de la formation de magnétite (Fe3O4)
Bimetallic nanoparticles (NPs) are known to present interesting catalytic properties justifying their use in several industrial processes in the domain of heterogeneous catalysis. However, their (chemical, geometrical, electronical) structure may evolve under realistic reactive atmosphere, involving a modification of their properties. In this multidisciplinary work, the aim is focused on the surface reactivity monitoring of these NPs under controlled gaseous environment. For this purpose, we developed an in situ spectrophotometer based on spatial modulation to monitor the structure evolution of a large assembly of NPs through the study of their localized surface plasmon resonance (LSPR). This global approach has been coupled with a more local approach by environmental transmission electronic microscopy (E-TEM). E-TEM observations have shown both composition and environmental effects on the chemical structure of Ag-In NPs. This structure evolves from a stable low-enriched indium alloy to a core@shell configuration with a shell composed of indium oxide as the indium atomic concentration increases. Furthermore, stable structure (core@shell, Janus, reduced system) domains were evidenced under reducing atmosphere, depending on the temperature and hydrogen pressure. Lastly, Ag-Fe NP oxido-reduction was monitored on the new setup through LSPR modifications. MET observations, environmental plasmonics and simulations (optical response, Monte-Carlo simulations) suggest that these metals are initially segregated, with an enriched-silver surface. The exposure to an oxidative atmosphere seems to induce the diffusion of iron onto the surface, followed by the formation of magnetite (Fe3O4)

Nous avons etudie la variation des proprietes magnetoresistives de multicouches argent/permalloy en fonction des epaisseurs de couches et des traitements thermiques. Ces multicouches sont fabriquees par pulverisation cathodique, sur des substrats de verre ou de silicium. L'influence des parametres de depot une fois connue (vitesse de depot, temperature des substrats), nous avons synthetise des echantillons dont les epaisseurs de couches varient continument entre 0,5 et 4,5 nm. Par diffractometrie x et magnetometrie, les epaisseurs ont ete determinees a 0,01 nm pres. Les couches croissent suivant une direction <111>. Les interfaces argent/permalloy sont abruptes, d'un a deux plans atomiques d'epaisseur, desordonnees topologiquement, inertes magnetiquement. Au moyen d'un banc de magnetoresistance, nous avons mis en evidence une zone de couplage antiferromagnetique, de 0,9 a 1,1 nm d'epaisseur d'argent. La variation des proprietes magnetoresistives est critique vis-a-vis de l'epaisseur d'argent, peu critique vis-a-vis de l'epaisseur du permalloy. Un modele simple nous permet d'estimer la valeur de l'energie de couplage, ainsi que les libres parcours moyens au sein des couches. L'evolution thermique, etudiee a l'aide d'un four sous vide, entraine d'importantes modifications structurales: demixion des interfaces, puis migration des defauts du massif aux interfaces, destratification enfin de la multicouche. Les proprietes magnetoresistives sont optimisees aux alentours de 250c, ce qui rend ces echantillons particulierement attractifs pour des applications

La ratio che anima questo studio riguarda il tentativo di tratteggiare la fisionomia del linguaggio politico italiano di questo inizio Millennio, sotto il profilo storico e metodologico. In particolare, si è sottolineato come il linguaggio politico sia uno dei luoghi privilegiati dove la semiosi della lingua si manifesta, come spazio autonomo tra un conoscere e un agire insieme, in virtù della sua prospettiva retorica. Questa rappresenta non una tecnica, bensì un punto di vista in grado di soddisfare sia una funzione conoscitiva che pragmatica, senza identificarsi completamente né con l’una, né con l’altra, rivelandosi così come l’unica prospettiva metalinguistica idonea a operare un “discorso sul discorso”. L’assunzione della retorica come prospettiva globale sulla cultura autorizza il tentativo di definire una categoria, il discorso politico fondativo, espressa dagli esempi dei Silvio Berlusconi e Walter Veltroni, pronunciati in occasione della presentazione dei due nuovi partiti da loro guidati: Forza Italia e Partito Democratico. L’analisi ha permesso di individuare le peculiarità delle strategie persuasive adottate dai due leaders politici e le loro diverse identità, grazie ad un impianto strutturale riconducibile ad una sorta di narrazione mitica. Infine, la dimensione retorica, nella sua accezione di linguaggio della modernità, consente di ricostruire gli stili espressivi della politica e quindi di proporre una storia del linguaggio politico italiano che, negli ultimi decenni, ha visto l’alternanza di forme dell’oscurità che si sono di volta in volta innestate su stili linguistici opposti: dal “politichese” al “gentese”.

Au cours de ce travail, une nouvelle technique ultramicroélectrochimique pour la caractérisation des grains individuels conducteurs de quelques dizaines de microns à été mise au point. Elle permet, en particulier, la détection d'espèces solubles formées à l'électrode sans devoir imposer des vitesses de balayage extrémement élevées comme c'est le cas avec les ultramicroélectrodes conventionnelles (10 MV/S suffisent). Les études sans ajout d'électrolyte support sont aussi possibles. La comparaison des voltampérogrammes de AG#2SE avec ceux obtenus par les méthodes classiques a mis en évidence qu'il est possible de caractériser des grains du minéral sans interférence contrairement aux pates de carbone. La technique a ensuite été utilisée parallélement à des méthodes spectroscopiques pour l'étude de l'adsorption de AG#+ et de HG#2#+ sur la pyrite FES#2 (pulpes à 0,5% en poids). Il s'avère que les spéciations de l'argent et du mercure à la surface de FES#2 dépendent fortement de la concentration des ions métalliques en solution. Dans le cas où l'argent est à faible concentration, seul AG#2S se forme. Quand la concentration est plus forte, de l'argent métallique est aussi présent. De même, selon la concentration en mercure, une ou deux espèces de stabilité différente se fixent à la surface de la pyrite. La quantité maximale de mercure s'adsorbant sur le minéral (3,5 10#-#5 MOL/G) est vingt fois moins importante que celle d'argent (6,6 10#-#4 MOL/G). Quand de la pyrite est conditionnée simultanément avec les ions AG#+ et HG#2#+, seul le mercure est adsorbé à sa surface. Il libère en solution l'argent si ce dernier était préalablement fixe sur le minéral. La quantité de mercure alors adsorbée atteint 3,2 10#-#4 MOL/G. Enfin, l'action du thymol sur la pyrite a été envisagée dans le but d'inhiber l'oxydation chimique du minéral. Les mesures électrochimiques ont montré que c'est le produit d'oxydation du thymol, et non lui-même, qui s'adsorbe sur la pyrite et limite son oxydation

La présente thèse de doctorat analyse l’influence du fusil à baïonnette sur la tactique de l’infanterie française au XVIIIe siècle. Les travaux concernant cette arme ont, jusqu’ici, surtout traité des modèles produits, des méthodes de fabrication et de l’approvisionnement des régiments. Notre approche est celle d’un historien au contact des collections d’un grand musée militaire. Elle consiste à étudier le fusil du point de vue du maniement et, plus généralement, de sa mise en œuvre contre l’ennemi. L’objectif est de comprendre comment l’armée royale s’est adaptée à une arme aux faibles capacités techniques et balistiques. Les sources exploitées sont nombreuses et variées : archives techniques et tactiques de l’armée de Terre, ouvrages imprimés relatifs à l’art de la guerre, objets des collections du musée de l’Armée, à Paris.La première partie est consacrée aux origines, au développement et à la description matérielle du fusil. La deuxième partie examine ses usages tactiques. Le grand débat qui en résulte, opposant les partisans de l’ordre profond aux défenseurs de l’ordre mince, fait l’objet d’une relecture documentée. L’entraînement des soldats, les conditions du combat de ligne et l’émergence de l’infanterie légère sont également étudiés. La troisième partie tente de mesurer l’efficacité du fusil : à l’observation de son rôle au cours des batailles de Höchstädt (1704), de Dettingen (1743), de Fontenoy (1745) et des Plaines d’Abraham (1759), succède l’analyse des blessures causées par les balles et les baïonnettes. Après un siècle d’emploi du fusil par l’armée de l’Ancien Régime, les bases tactiques des guerres de la Révolution et de l’Empire sont posées
This PhD dissertation analyses the influence of the flintlock musket upon the French infantry in the 18th century. Until now, studies of this weapon have particularly focused on the manufactured types, the manufacturing methods and regiment supplies. Our approach is one of a historian’s, working in a major military museum. It consists of studying the handling of the flintlock and more broadly speaking, how it was used against the enemy. The objective is to understand how the royal army managed to adapt to a weapon with little technical and ballistic capacity. We used various source materials: the technical and tactical archives of the French Army, numerous printed works on the art of warfare and objects from various collections of the Army museum in Paris.The first part of this dissertation is devoted to the origins, the development and the technical description of the musket. The second part examines its tactical uses. The main ensuing debate opposing supporters of the deep order against those of the thin line order has been re-examined in the light of new documents. The soldiers’ training, the conditions of line warfare and the emergence of the light infantry are also studied. The third part tries to assess the efficiency of the musket: the part it played during the battles of Blenheim (1704), Dettingen (1743), Fontenoy (1745) and the Plains of Abraham (1759) is carefully studied, then an analysis of the wounds caused by its bullets and bayonets logically follows. After a century of the Old Regime Army's use of the musket, the tactical basis of the French revolutionary and Napoleonic wars are set down

La présente thèse de doctorat analyse l’influence du fusil à baïonnette sur la tactique de l’infanterie française au XVIIIe siècle. Les travaux concernant cette arme ont, jusqu’ici, surtout traité des modèles produits, des méthodes de fabrication et de l’approvisionnement des régiments. Notre approche est celle d’un historien au contact des collections d’un grand musée militaire. Elle consiste à étudier le fusil du point de vue du maniement et, plus généralement, de sa mise en œuvre contre l’ennemi. L’objectif est de comprendre comment l’armée royale s’est adaptée à une arme aux faibles capacités techniques et balistiques. Les sources exploitées sont nombreuses et variées : archives techniques et tactiques de l’armée de Terre, ouvrages imprimés relatifs à l’art de la guerre, objets des collections du musée de l’Armée, à Paris.La première partie est consacrée aux origines, au développement et à la description matérielle du fusil. La deuxième partie examine ses usages tactiques. Le grand débat qui en résulte, opposant les partisans de l’ordre profond aux défenseurs de l’ordre mince, fait l’objet d’une relecture documentée. L’entraînement des soldats, les conditions du combat de ligne et l’émergence de l’infanterie légère sont également étudiés. La troisième partie tente de mesurer l’efficacité du fusil : à l’observation de son rôle au cours des batailles de Höchstädt (1704), de Dettingen (1743), de Fontenoy (1745) et des Plaines d’Abraham (1759), succède l’analyse des blessures causées par les balles et les baïonnettes. Après un siècle d’emploi du fusil par l’armée de l’Ancien Régime, les bases tactiques des guerres de la Révolution et de l’Empire sont posées
This PhD dissertation analyses the influence of the flintlock musket upon the French infantry in the 18th century. Until now, studies of this weapon have particularly focused on the manufactured types, the manufacturing methods and regiment supplies. Our approach is one of a historian’s, working in a major military museum. It consists of studying the handling of the flintlock and more broadly speaking, how it was used against the enemy. The objective is to understand how the royal army managed to adapt to a weapon with little technical and ballistic capacity. We used various source materials: the technical and tactical archives of the French Army, numerous printed works on the art of warfare and objects from various collections of the Army museum in Paris.The first part of this dissertation is devoted to the origins, the development and the technical description of the musket. The second part examines its tactical uses. The main ensuing debate opposing supporters of the deep order against those of the thin line order has been re-examined in the light of new documents. The soldiers’ training, the conditions of line warfare and the emergence of the light infantry are also studied. The third part tries to assess the efficiency of the musket: the part it played during the battles of Blenheim (1704), Dettingen (1743), Fontenoy (1745) and the Plains of Abraham (1759) is carefully studied, then an analysis of the wounds caused by its bullets and bayonets logically follows. After a century of the Old Regime Army's use of the musket, the tactical basis of the French revolutionary and Napoleonic wars are set down

Nous presentons une etude des proprietes structurales, magnetiques et de transport electronique de multicouches co/cu et nife/ag ainsi que d'alliages granulaires (cofe)ag. La magnetoresistance geante de ces systemes constitue le theme principal de la these. Nous avons developpe une procedure experimentale permettant la preparation d'echantillons mesurables en geometrie perpendiculaire (cpp), dans laquelle les lignes de courant sont perpendiculaires aux interfaces entre couches. Comme attendu l'effet de magnetoresistance geante est renforce dans cette geometrie. Une modelisation semiclassique du transport planaire (type camley et barnas) permet de determiner les parametres microscopiques du transport electronique: libres parcours moyens et coefficients de transmission des interfaces pour les electrons des deux categories de spin. Cette modelisation a ete appliquee aux multicouches nife/ag et les valeurs des parametres seront precises/verifies par les mesures de transport perpendiculaire. Le systeme nife/ag fait l'objet d'une etude experimentale detaillee de la magnetoresistance geante planaire a temperature ambiante: influence des epaisseurs des differentes couches, du dopage des interfaces par du cobalt, ceci du fait de ses proprietes magnetoresistives particulierement attractives: fortes amplitude et sensibilite de la magnetoresistance. Nous avons egalement entrepris sur ce systeme des mesures de la variation angulaire de la magnetoresistance geante (geometries cip et cpp). D'un point de vue theorique, l'influence sur la magnetoresistance geante de la quantification du vecteur d'onde associe aux electrons de conduction ainsi que de l'existence de marches de potentiel aux interfaces dans les structures en couches a ete etudiee dans le formalisme quantique de kubo. Enfin l'etude du systeme granulaire (cofe)ag permet de mettre en relief l'importance capitale de la nanostructure ainsi que le caractere intermediaire entre geometrie cip et cpp que revet le transport electronique dans ce type d'echantillons

Les multicouches magnetoresistives ni#8#1fe#1#9/ag elaborees par pulverisation cathodique de type triode sont connues pour etre un materiau a haut potentiel d'applications. Cette these se propose d'en ameliorer les proprietes magnetoresistives par deux methodes distinctes, ceci dans le but d'utiliser ce type de materiau lors de la conception de capteurs de champ magnetique. L'une des methodes consiste a modifier la composition de la couche magnetique. Deux systemes (co#7#0fe#3#0/ag et ni#6#6co#1#8fe#1#6/ag) ont ete etudies. Les multicouches co#7#0fe#3#0/ag presentent un interet assez limite pour les applications de part leurs performances (champs a saturation eleves) et de part les difficultes d'elaboration liees aux tres faibles epaisseurs de la couche magnetique (environ 7 a). Les multicouches ni#6#6co#1#8fe#1#6/ag sont beaucoup plus interessantes et permettent de doubler la sensibilite de la reponse magnetoresistive des multicouches ni#8#1fe#1#9/ag (0. 4%/oe contre 0. 2%/oe). La deuxieme methode consiste a utiliser un procede d'elaboration different (pulverisation cathodique de type cibles face a face) dans lequel le substrat defile au dessus des differentes cibles. Ce faisant, nous induisons une anisotropie magnetique uniaxiale dans le plan de la multicouche. Cet effet augmente considerablement la sensibilite et, apres recuit, une valeur de 0. 6%/oe a ete obtenue sur une plage de champ de 0 a 10 oe. Les perspectives offertes par cet effet d'anisotropie sont particulierement interessantes. Des simulations montrent qu'il est possible, en controlant l'intensite de l'anisotropie, de recueillir une sensibilite tres elevee sur toute l'amplitude de l'effet magnetoresistif. Il est egalement possible d'induire une anisotropie supplementaire par l'intermediaire de recuits sous champ magnetique

Le but de cette these etait l'etude experimentale de l'origine theorique tres discutee de la magnetoresistance geante des multicouches magnetiques, en particulier lorsque le courant est applique perpendiculairement au plan des couches (cpp-mr). Dans cette geometrie, les resistances des echantillons sont de l'ordre du nano-ohm au micro-ohm, et nous souhaitions voir des variations de quelques pour-cent de celles-ci avec un courant de mesure de 100 ma maximum. La sensibilite requise etait donc le pico-volt. Durant cette these, nous avons tout d'abord developpe des dispositifs experimentaux atteignant la sensibilite extreme de 10 femto-volt par racine de hertz, et utilisant des principes de mesure originaux dans ce domaine d'investigation. Avec ces dispositifs, nous avons principalement etudie la variation angulaire de la cpp-mr des multicouches (ag/co/ag/nife) et (ag/nife). Les resultats experimentaux obtenus ont ete tout d'abord discutes dans le cadre des modeles theoriques preexistants a cette etude. Puis un modele quantique a ete developpe pour decrire specifiquement le cas des configurations non-colineaires des aimantations des couches ferromagnetiques successives. La comparaison de ce modele avec les resultats experimentaux a montre que les interferences entre les ondes coherentes associees aux spins up et down des electrons contribuent a la cpp-mr, que les electrons qui participent a la conductivite en cpp sont des electrons de type s, et que la contribution principale a la cpp-mr est la diffusion dependante du spin sur les defauts de volume et d'interfaces des couches ferromagnetiques

Gli ormai classici studi di Frances A. Yates e di Paolo Rossi sull’ars memoriae si chiudevano entrambi nel nome di Leibniz, poiché è possibile, scriveva la studiosa warburghiana, che con il filosofo di Lipsia, nel quale culmina e allo stesso tempo si esaurisce la tradizione sia lulliana sia ermetico-occultista, «si arresti l’influsso dell’arte della memoria come fattore nei progressi fondamentali dell’Europa»1 . Eppure, continua Yates, libri sulla mnemotecnica continueranno ad apparire (più avanti ne vedremo due esempi), e «probabilmente si potrebbe scrivere un altro libro che estendesse l’esame dell’argomento ai secoli successivi»2 . Le pagine che seguono non hanno un obiettivo così ambizioso, ma mirano a rintracciare ciò che resta, o non resta, della disciplina inaugurata da Simonide nell’arco cronologico che va da Vico a Leopardi. Tra questi due estremi, si è scelto di indagare testi e autori meno approfonditi dalla critica (Muratori, Conti, Genovesi e Bettinelli) con uno sguardo attento a una serie di fattori socioculturali di vasta portata: la crisi della retorica e la sempre più diffusa ‘scritturalizzazione’ della memoria (e dunque il diverso rapporto con la voce e con le immagini); la scissione tra segni, parole e cose (ovvero, in termini foucaultiani, il passaggio dalla cultura della somiglianza a quella della differenza) 3 ; l’esplosione del moderno mercato editoriale, la minaccia del troppo e il ‘collasso’ dell’enciclopedia; o ancora, l’affermarsi di un’estetica dell’originalità e la differente funzione attribuita alla memoria e alla fantasia nei processi creativi e conoscitivi (entrambe, almeno da Cartesio in poi, associate all’errore, ma con significative eccezioni, tra le quali, per non dire di Vico e Leopardi, vi è senz’altro Bettinelli e in parte anche Conti). [...].

Con questa tesi di dottorato sono state studiate le dinamiche di paesaggio dell’Italia peninsulare legate a processi di cambiamento di copertura/uso del suolo e ai recenti incendi, nel contesto del cambiamento climatico in atto. I cambiamenti di uso del suolo sono stati analizzati principalmente nelle aree montane dell’intero arco appenninico, mentre gli effetti sul paesaggio di due recenti e rilevanti stagioni di incendi sono stati analizzati estendendo l’area di studio all’Italia peninsulare e alle due isole maggiori (Sardegna e Sicilia). In primo luogo, abbiamo ritenuto appropriato l’utilizzo di una meta-analisi come strumento preliminare di sintesi di dinamiche eterogenee evidenziate da molteplici casi di studio situati su un’ampia area geografica, poiché la ricerca in materia adotta solitamente un approccio basato sul singolo caso di studio nell’analisi del cambiamento. Dopo aver selezionato 51 articoli pubblicati e 57 relativi casi di studio, abbiamo esaminato i dati e standardizzato la metodologia di trattamento degli stessi per ottenere una nuova serie di dati omogenei per un’analisi comparativa delle dinamiche di paesaggio. Il passo successivo è stato quello di adottare una metodologia standard di campionamento di repliche di paesaggi per quantificare i cambiamenti a scala regionale. Abbiamo selezionato 10 siti rappresentativi lungo l’Appennino e studiato i cambiamenti di copertura e di struttura del mosaico paesaggistico confrontando diverse esposizioni (Nord-est vs Sud-ovest) e fasce altitudinali (bassa vs alta quota) e analizzando i fattori principali che influenzano le dinamiche bosco/non-bosco. I recenti cambiamenti di uso/copertura del suolo e del clima presso tutto il bacino del Mediterraneo hanno stanno alterando il regime storico di incendi e portando all’aumento della loro frequenza, superfice e severità. Nell’ultimo capitolo, abbiamo creato un database di grandi incendi forestali (> 100 ha) attraverso tecniche di telerilevamento e specifici criteri di selezione, al fine di studiare le caratteristiche, la severità e gli effetti sul paesaggio di due rilevanti stagioni di incendi forestali (2007 e 2017) nell’Italia peninsulare e principali isole. I risultati preliminari ottenuti offrono un quadro comparativo delle caratteristiche di grandi incendi di annate particolarmente siccitose, che si stima saranno sempre più frequenti nel contesto del cambiamento climatico in atto.
This research aimed to study landscape dynamics along the Italian peninsula, due to land use/cover shifts and recent wildfires, within the contest of climate change. Land use changes were mainly focused on the mountain areas along the whole Apennines range, whereas the landscape effects of two recent and extreme fire seasons were assessed along the Italian peninsula and the two major islands (Sardinia and Sicily). Firstly, we considered a meta-analysis an appropriate and preliminary tool for summarizing general patterns and heterogeneous findings from several case-studies over a large geographic area, since land-use science usually adopts the case-study approach to investigate landscape changes. Out of 51 published articles and different databases that referred to 57 case-studies, we explored heterogeneous data sets and standardized the processing methods to obtain a new set of homogeneous data for a comparative landscape change analysis. Secondly, we used a replicate landscape approach and a systematic sampling design for quantifying changes at regional scale. We selected 10 representative sites located along the Apennines and investigated land-cover changes and landscape configurational shifts comparing different slope aspects (North-East vs South-West slopes) and altitudinal zones (low elevation vs high elevation) and assessing the main drivers of the non-forest/forest dynamics. Recent changes of land use/cover and climate in the Mediterranean basin altered historical fire regimes and led to an increase of the frequency, area and severity of wildfires. In the last chapter, we created a dataset of large wildfires (>100 ha) using remote sensing techniques and adopting specific selection criteria in order to study the occurrence, the severity and the landscape effects of two major forest fire seasons (2007 and 2017) in peninsular Italy and Sicily and Sardinia islands. Preliminary results offer a comparative picture of large fire features in dry years which are expected to occur more frequently in a climate change scenario.

Superati «novant’anni d’impazienza» e dopo un lungo periodo votato all’autocommento e all’esplorazione delle proprie intenzioni, Raffaele La Capria ha raccolto le sue opere in due Meridiani curati da Silvio Perrella. La Capria ne ha celebrato l’uscita nella prolusione inaugurale di Salerno Letteratura, poi confluita nel breve autoritratto narrativo "Introduzione a me stesso" (2014). In questa sede, l’autore è tornato su alcuni punti essenziali della sua riflessione sulla scrittura, come la relazione, reciproca e ineludibile, fra tradizione e contemporaneità. All’epilogo del «romanzo involontario» di una vita, La Capria guarda retrospettivamente alla propria esperienza come ad un’autentica educazione intellettuale. Perciò, muovendo da un’intervista inedita del 2015, riportata integralmente in appendice, la tesi ha l’obiettivo di ricostruire l’apprendistato letterario di La Capria dai primi anni Trenta, quando l’autore ancora frequentava il ginnasio, fino all’inizio dei Sessanta, quando ottenne il premio che ne avrebbe assicurato il successo. Il percorso, che riesamina l’intera bibliografia lacapriana nella sua varietà e nella sua stratificazione, si articola in una serie di fasi interdipendenti: la partecipazione indiretta alle iniziative dei GUF (intorno alle riviste «IX maggio» e «Pattuglia»); l’incursione nel giornalismo e l’impegno culturale nell’immediato dopoguerra (sulle pagine di «Latitudine» e di «SUD»); l’attività di traduttore dal francese e dall’inglese (da André Gide a T.S. Eliot); l’impiego alla RAI come autore e conduttore radiofonico (con trasmissioni dedicate a Orwell, Stevenson, Saroyan e Faulkner); la collaborazione con «Il Gatto Selvatico», la rivista dell’ENI voluta da Enrico Mattei e diretta da Attilio Bertolucci; e le vicende editoriali dei suoi primi due romanzi, “Un giorno d’impazienza” (1952) e “Ferito a morte” (1961), fino alla conquista dello Strega. La rilettura dell’opera di uno scrittore semi-autobiografico come La Capria, attraverso il costante riscontro di fonti giornalistiche, testimonianze epistolari e documenti d’archivio che avvalorano e occasionalmente smentiscono la sua versione dei fatti, diventa allora un’occasione per immergersi nella sua mitografia personale e avventurarsi in territori finora poco esplorati: come la ricostruzione del suo profilo culturale, a partire dal milieu in cui La Capria vive e opera, o l’incidenza delle letture e delle esperienze giovanili sulla sua prassi letteraria.

This study addressed the development of natural regeneration of tree species over the period 2009-2016 in a temperate fir-beech old-growth forest left to a spontaneous development since 1930s. The research site was located in the strictly protected National Nature Reserve Salajka, lying in the Western Carpathians mountain range. Ungulate game browsing, establishment and mortality of natural regeneration as the main drivers of species coexistence were studied, using two alternative sampling methods, permanent network of 98 inventory plots regularly positioned across the whole forest reserve and transect with 54 transect plots. Beech was found to secure gradually absolute dominance over other tree species in natural regeneration. The growth of fir, maple and spruce was hindered by browsing since the individuals rarely exceeded the height of 0.5 m. Further, the resource concentration effect was found in fir as browsing was more intense under high conspecific densities. Establishment and mortality of fir and beech differed, suggesting the species-specific life-history strategies. The results demonstrated the importance of regular and inextensive establishment of fir and huge but relatively less frequent establishment of beech. Mortality overweighed establishment in both species, though fir ratio tended to be almost balanced. The height of natural regeneration was revealed to be the only good predictor of mortality. Browsing, establishment and mortality of natural regeneration comprise an important part of forest regeneration processes and their role should be acknowledged by both forest and nature conservation management.