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1
O’Flaherty, Craig. "Blue ring of fire." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/63615.
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My poems are reflections of shape, colour and emotions expressed through imagery. Their unsentimental landscape-realism echo my own feelings as well as broader human dimensions of contradiction and uncertainty, without trying to resolve them. In the same way that photography is the art of 'painting with light', my poems seek a language that evokes light and darkness. They aspire to what Keats said when writing about ‘negative capability’: “Poetical character has no self, it is anything and nothing, it has no character and enjoys light and shade”. My poems explore what I have learned about form – how line-length, syntax and musicality can add grace and energy to language. Poets that have influenced me include the classical Chinese poets such as Du Fu and Li Po, and the Generation of 27 Spanish poets, such as Antonio Machado and Leon Felipe.
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Bigio, Erica Renee. "Late Holocene Fire and Climate History of the Western San Juan Mountains, Colorado: Results from Alluvial Stratigraphy and Tree-Ring Methods." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311587.
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In the past few decades, wildfires have increased in size and severity in the Southwest and across the western US. These recent trends in fire behavior are a drastic change in arid, ponderosa pine and mixed conifer forests of the Southwest compared with tree-ring records of fire history for the past ~ 400 years. This study presents a late Holocene record (~ 3,000 years) of fire history and related changes in fire regimes with climate variability over annual to multi-decadal time scales. Tree-ring and alluvial-sediment sampling sites were paired in four small, tributary basins located in the western San Juan Mountains of Colorado. In our study sites, tree-ring records show that fire return intervals were longer and fire behavior was more severe on the north-facing slopes with relatively dense mixed conifer stands. Increased fire barriers and steep topography decreased the fire frequency and extent relative to gentle terrain elsewhere in the range and leading to a lack of synchrony among fire years in different parts of the study area. The alluvial-sediment record showed four peaks in high-severity fire activity over the past 3,000 years ranging between 200 - 400 years in length. The timing of peaks coincided with decadal-length drought episodes and were often preceded by multiple decades of above average winter precipitation. The sampling of alluvial-sediment and tree-ring data allowed for site-level comparisons between recent alluvial deposits and specific fire years interpreted from the tree-ring records. We found good correspondence between the type of fire-related sediment deposit (i.e. geomorphic response) in the alluvial record and the extent of mixed and high-severity fire estimated from the tree-ring record, and the correspondence was well-supported by the debris flow probability model results. The two paleofire data tend to represent particular components of the historical fire regime, with alluvial-sediments biased towards infrequent, high-severity events during recent millennia, and the tree-ring record biased toward lower severity fires during recent centuries. The combined analyses of different paleofire proxy types in the same study sites, therefore, can enhance and expand our understanding of fire and climate history beyond what is possible with either proxy alone.
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Kilpatrick, Mackenzie. "A tree ring based fire history of the Clover Mountains, Lincoln County, Nevada." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1467753.
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McEwan, Ryan W. "Tree-Ring Based Reconstructions of Disturbance and Growth Dynamics in Several Deciduous Forest Ecosystems." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1150748370.
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Sutherland, Elizabeth F. (Elizabeth Fyfe). "Fire, resource limitation and small mammal populations in coastal eucalypt forest." Thesis, School of Biological Sciences, 1999. http://hdl.handle.net/2123/5344.
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Pohl, Kelly A., Keith S. Hadley, and Karen B. Arabas. "Decoupling Tree-Ring Signatures of Climate Variation, Fire, and Insect Outbreaks in Central Oregon." Tree-Ring Society, 2006. http://hdl.handle.net/10150/262623.
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Dendroecological methods play a critical role in developing our understanding of forest processes by contributing historical evidence of climate variability and the temporal characteristics of disturbance. We seek to contribute to these methods by developing a research protocol for decoupling radial-growth signatures related to climate, fire, and insect outbreaks in central Oregon. Our methods are based on three independent, crossdated tree-ring data sets: 1) a 545-year tree-ring climate reconstruction, 2) a 550-year fire history, and 3) a 250-year pandora moth outbreak history derived from host (Pinus ponderosa) and non-host (Abies grandis-Abies concolor) tree-ring chronologies. Based on these data, we use visual criteria (marker and signature rings), statistical comparisons, and Superposed Epoch Analysis (SEA) to identify the timing of growth anomalies and establish the temporal relationships between drought, climate variation (ENSO and PDO), fire events, and pandora moth (Coloradia pandora) outbreaks. Our results show pandora moth outbreaks generally coincide with periods of below-average moisture, whereas fire in central Oregon often follows a period of wetter than average conditions. Fire events in central Oregon appear to be related to shifts in hemispheric climate variability but the relationship between fire and pandora moth outbreaks remains unclear.
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Grissino-Mayer, Henri Dee, and Henri Dee Grissino-Mayer. "Tree-ring reconstructions of climate and fire history at El Malpais National Monument, New Mexico." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/191192.
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The purpose of this research was to: (1) reconstruct climate for the malpais region from long-lived trees and remnant wood; (2) reconstruct the fire history of forests in the malpais; and (3) investigate short-term and long-term relationships between wildfire and climate. To reconstruct climate, I calibrated a 2,129 year long tree-ring chronology (136 BC - AD 1992) with annual rainfall (previous July to current July). Since AD 100, seven major long-term trends in rainfall occurred. Above normal rainfall occurred during AD 81-257, 521-660, 1024-1398 and 179 1- 1992, while below normal rainfall occurred during AD 258-520, 661-1023 and 1399- 1790. The prolonged drought from AD 258-520 was unsurpassed in its intensity, while rainfall during the most recent 200 years has exceeded any since AD 660. The reconstruction of long-term climate trends confirmed the general sequence of environmental change over the last 2,000 years for the southern Colorado Plateau. To reconstruct past fire occurrences, 217 fire-scarred trees were collected from nine sites representing the major habitat types of the malpais and dendrochronologically dated. Fire frequency was highest at sites on cinder cones and on the highly-weathered basalt flows (ca. once every five years), and lowest on the isolated kipukas and on the Hoya de Cibola Lava Flow (once every 10-12 years). Fire frequency decreased along a north to south gradient, reflecting changing vegetation properties. Combined information revealed fire occurred once every two years, while more widespread fires occurred once every 2.5 years. Fires were largely asynchronous between sites, suggesting the malpais landscape effectively hinders fire spread. Past fire history at El Malpais was characterized by four temporally distinct periods: (1) FH-1 (prior to 1782): high fire frequency, patchy fires, throughout the growing season; (2) FH-2 (1795 - 1880): longer fire intervals, widespread fires, mostly early season fires; (3) FH-3 (1893 - 1939): even longer intervals, decreased widespread fires; (4) FH-4 (1940 - 1992): longest fire-free periods during the last 600 years. The increase in rainfall and the simultaneous change in fire regimes ca. 1790 was likely related to an increase in summer monsoonal rainfall due to changes in hemispheric circulation patterns. The decrease in fire spread ca. 1880 was most likely due to intense sheep grazing, while the change ca. 1940 reflects greater efficiency in fire suppression techniques. The presettlement fire regime emphasizes that the current absence of fire in the monument exceeds the historical range of variability established for the presettlement period. Unless effects of past humanrelated disturbances are mitigated, fire regimes of El Malpais will continue to favor high-intensity, catastrophic fires.
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O'Connor, Christopher Daniel. "Spatial and temporal dynamics of disturbance interactions along an ecological gradient." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311565.
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Interactions among site conditions, disturbance events, and climate determine the patterns of forest species recruitment and mortality across landscapes. Forests of the American Southwest have undergone significant changes over a century of altered disturbance regimes, human land uses, and changing environmental conditions. This study reconstructs the interactions between fire, spruce beetle outbreaks, climate, and anthropogenic factors and their influence on the species composition, spatial extent, and structure of four upper elevation forest types. We found that fire-climate associations changed following fire exclusion and recent high-severity fires occurred during less severe conditions than in several larger, lower severity fires in the historical record. Contemporary fires are burning with higher severity than similarly-sized historical fires, suggesting a shift toward higher-severity fire as a result of changes to forest structure and fuels over much of the upper elevation forest. In high elevation forests, the area occupied by Engelmann spruce and corkbark fir doubled in size over the four decades following fire exclusion. The increase in spruce beetle outbreak size and severity in the 20th century appears to be linked to significant expansion of host extent, accelerated growth of spruce in mixed-conifer forest, and incidence of anomalously warm summer temperatures followed by up to a decade of low precipitation. Trends toward warming, drying conditions are expected to increase the risk of future high-severity outbreaks, especially in locations of recent spruce population expansion. Forest conversion from disturbance-adapted to competition-adapted species following fire exclusion was a function of site productivity. Species assemblages in the lowest and highest productivity sites were the most stable over the century following fire exclusion. Frequent low severity fires maintained the stocking of forests in moderate productivity sites below their biological potential, conferring a degree of resistance to drought, insect outbreaks, and high-severity fire prior to fire exclusion. Current forests located on moderate productivity sites are now the most vulnerable to drought and future disturbance. Aggressive action to restore historical species composition, stocking and fire component of these forests may return resilience to this system in the face of projected changes to fire and climate dynamics.
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Bassett, Peter Glen. "Playing with Fire: The Pursuit of a Wagner Performance Tradition in Adelaide in the Decade 1995-2005, and Factors Impeding its Realisation." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/366689.
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The productions of the Ring in Adelaide in 1998 and 2004 and Parsifal in 2001 were landmarks in Australia’s cultural history. They were artistically successful, attracted considerable commercial benefits to South Australia and generated nationwide expectations of further performances. Yet those expectations went unfulfilled. The success of Adelaide’s Wagner decade had depended on an effective combination of artistic vision, management skills, politics and patronage. This thesis is an analysis of those factors and the extent to which they at first enabled and then jeopardised the dream of an on-going Wagner performance tradition in the South Australian capital.
Politics provided the incentive for this venture when the South Australian Government sought to achieve a major ‘cultural tourism’ success in the wake of a major ‘sports tourism’ calamity - the loss of the Australian Formula One Grand Prix to Victoria. The goal of emulating the ‘Wagnerian’ city of Seattle was also embraced at the political level. The General Director of the State Opera of South Australia (SOSA), Bill Gillespie, recommended the hiring of a Paris production of the Ring for restaging in Adelaide in 1998. A dedicated Ring Corporation was established to oversee the production, and the outcome was a notable success. Performances of Parsifal (the first staging of this work in Australia) which followed in 2001, confirmed that the pursuit of a Wagner performance tradition in Adelaide was a viable goal.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Queensland Conservatorium<br>Arts, Education and Law<br>Full Text
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Johnson, Jason R. "Developing the Axisymmetric Expanding Ring: A High Strain-Rate Materials Characterization Test." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1387807565.
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Sundström, Ulla. "En järnrings förbannelse : en studie i religionshistoria om en ring från Gästriklands vikingatid." Thesis, University of Gävle, Department of Humanities and Social Sciences, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-354.
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<p>Mitt syfte med denna studie av Häckelsängsringen är att ta reda på om den verkligen är från vikingatiden samt om den har haft en eds-, rit- eller kultfunktion? Finns det någon vikingatida kult i området som kan komma ifråga när det gäller denna ”mystiska ring”? Till min hjälp har jag tagit litteratur som talar om ringar och eder till exempel de Isländska eddorna. För att se om det finns en vikingatida kult i området har jag besökt Hamrånge socken, både själv och tillsammans med arkeologer. Jag har studerat länsmuseets faktarum och fornminnesregistret. I fornminnesregistret har jag hittat platser såsom en reliklund med mycket gamla lindar, en tänkbar offerkälla, en stenlagd cirkel som kan vara en tingsring samt att i närheten finns ett område som på gamla kartor kallas Lundåker, en tydlig odling av hassel. Allt detta sammantaget tyder på en vikingakult i området. Järnringen har krokar på insidan och dessa har jag försökt att tolka. Det jag kommer fram till är att dessa krokar kan symbolisera olika saker beroende på vad man skulle ha den till för stunden. Det finns ett tydligt mönster som visar ett vikingaskepp mellan två krokar. Krokarna i sig själv anser jag symboliserar eldstål och dessa tillskriver jag vikingaguden Tor.</p>
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Carter, Alan. "Ring of Fire: Crime Fiction as a Means of Examining Projections of Australian National Identity into the Asia-Pacific Region: A Novel and Exegesis." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/76145.
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This thesis consists of a creative component – the novel Crocodile Tears, and a theoretical essay. Both address the question: How has Australian crime fiction worked to reinforce or undermine projections of Australian national identity into the Asia-Pacific region? Crocodile Tears is a detective story reuniting Indigenous “spook” Rory Driscoll with Detective Philip Kwong of the WA police. A retiree is murdered in suburban Perth, the trail leads to Timor Leste, and its blood-soaked history.
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Chavarria, Dana, Rubi Ramos, and Carlos Raymundo. "Development of a hybrid heating system based on geothermal–photovoltaic energy to reduce the impact of frosts on inhabitants of rural areas in the ring of fire, southern Peru." Springer Science and Business Media Deutschland GmbH, 2019. http://hdl.handle.net/10757/656249.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.<br>The recent climate change has forced people to live in extreme conditions, either excessive heat or cold, implying that they must adapt to survive in these situations. However, there are people who, because of their geographical condition and lack of resources, lack the means and tools to combat these climate changes. The context of this study is provided in a rural town located in the Arequipa region (Peru), whose inhabitants have to fight against frosts of up to −20 °C in an area without electricity. A viable solution to this problem is found through the design and implementation of a heating system using geothermal and photovoltaic energy, which are resources found in the area, according to a report of the Ministry of Energy and Mines. This study analyzes and researches the geographical and meteorological conditions of the region, for validating, through theory and simulations, whether the proposed system can supply the thermal energy required to maintain the indoor temperature at a minimum of 15 °C under extreme conditions. The system is designed after analyzing the best technological options and techniques currently available in the context studied for its ultimate financing and establishing guidelines and indicators for monitoring results.
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Aiginger, Karl, and Heinz Handler. "Fostering a Dynamic and Stable Neighborhood for Europe." Academic Research Centre of Canada, 2018. http://epub.wu.ac.at/6630/1/1923%2D7529%2D2018%2D04%2D39%2D16.pdf.
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Europe is less dynamic than other areas in the world. The European Union will lose its position as the largest economic region, with the share in world output decreasing to less than 15% in 2050. This article designs a strategy based on which Europe can increase its internal dynamics, connect with its dynamic neighborhood and stabilize its eastern and southern regions. These regions are currently searching for development paths different from those in the US and China. The envisaged strategy learns from past errors, counteracts "my country first calls", balances uneven trade and investment pacts, and prevents land and resource grabbing. A new partnership strategy with neighbors in Eurasia, the Middle East and Africa will enable Europe to overcome its growth fatigue. It could help to reshape globalization and convert the current "ring of fire" into a "ring of friends". Then, together with its neighbors, Europe could still be an important economic region in 2050, on par with China and larger than the US plus its neighbors.
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Sbert, Carlsson Carla. "Mining from the Lens of Ecological Law: Obstacles and Opportunities for Re-formation." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39178.
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Ecological law is a legal paradigm that is emerging in response to the current ecological crisis. This thesis explores the main challenges and opportunities in existing laws, particularly in the context of mining, for a shift to this new paradigm. A synthesis of the main critiques, scientific and economic concepts, legal scholarship and proposals that contribute to the theory of ecological law is presented, along with a discussion of the relationship and potential synergies of ecological law with Indigenous legal traditions and with Green Legal Theory. An analytical tool to help improve the understanding of what a shift to ecological law would entail–a lens of ecological law–is proposed, building on ecological law scholarship. The lens of ecological law consists of three principles of ecological law: ecocentrism, ecological primacy and ecological justice. This lens is applied to three different legal approaches to mining in order to reflect on the implications for a shift to ecological law in this sector: El Salvador’s ban on metal mining; mineral extraction proposed in Ontario’s Ring of Fire; and mining in the context of the rights of Mother Earth and vivir bien recognized in Bolivian law. Conclusions on the obstacles and opportunities for a shift to ecological law in mining, and recommendations on the ecological law re-formation of mining and on further research are offered in closing. Ecological law promises to be an important part of building an ecologically just society.
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Matuska, Vit. "Five-membered sulfur-nitrogen ring compounds." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/828.
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Robin, Vincent. "Reconstruction of fire and forest history on several investigation sites in Germany, based on long and short-term investigations - Multiproxy approaches contributing to naturalness assessment on a local scale." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30057.
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Sur la base de constats globaux concernant l’importance d’appliquer des modes de gestion durable des zones forestières et le manque d’investigation concernant l’histoire passée des feux en Europe centrale, il a été entrepris de reconstruire l’histoire des événements de feux et de la dynamique forestière pour des sites d’étude en Allemagne. L’ensemble des données obtenues et analysées ont été utilisées pour l’évaluation du niveau de naturalité des sites étudiés, cette notion étant essentielle pour la mise en place d’une gestion durable, et/ou pour des projets de conservation et / ou de restauration des systèmes perturbés. Concernant les dynamiques des écosystèmes en Europe centrale, il a été souvent mis en évidence que l’homme joue un rôle essentiel depuis des millénaires. Par conséquent, l’approche historique des événements de feux et de la dynamique forestière à été réalisée sur de longues échelles temporelles. Neuf sites d’étude ont été sélectionnés incluant une large gamme de systèmes forestiers d’Europe centrale. Les sites d’études sont répartis dans deux zones générales d’étude : le nord de l’Allemagne (Schleswig-Holstein), qui comprend quatre sites d’étude, et le centre de l’Allemagne (le Harz), qui comprend cinq sites d’étude. Quatre disciplines ont été principalement utilisées. Pour définir l’état actuel des sites d’études ceux-ci ont été caractérisés, utilisant divers indicateurs dendrométriques concernant la structure et la composition des parcelles analysées. Pour obtenir des informations à propos de la dynamique forestière des peuplements forestiers en place des analyses dendroécologiques ont été utilisées. Pour analyser la dynamique forestière sur une longue échelle temporelle, à une échelle spatiale comparable, des analyses pédoanthracologiques ont été menées, combinées à des analyses de sols. De plus, des analyses anthracologiques de séquences de tourbes ont été réalisées, fournissant, combinées avec les données pedoanthracologiques, des enseignements à propos de l’histoire des incendies. L’état actuel et la dynamique forestière récente des sites étudiés indiquent divers niveaux de complexité des peuplements forestiers, correspondant souvent à divers niveaux postulés d’impact anthropique. Il a été obtenu huit chronologies moyennes, standardisées en haute et moyenne fréquences, âgées au maximum de 1744 et au minimum de 1923 ans. A partir de ces chronologies des changements dans les conditions de croissance de peuplements forestiers ont été mises en évidence. Basées sur un ensemble de 71 charbons de bois datés par radiocarbone, il a été mis en évidence, à l’échelle locale et globale, deux principales phases présentant plus d’événements de feux datés, une durant le Pléistocène supérieur/Holocène inférieur, une autre durant l’Holocène supérieur. Pour les deux phases identifiées des forçages climatique et anthropogénique ont été respectivement postulés comme déterminisme des occurrences de feux. Finalement, les différentes données collectées ont été utilisées de façon combinée pour reconstruire l’histoire des feux et des forêts des sites étudiés, afin de contribuer à l’évaluation de leur niveau de naturalité<br>Considering two global observations in Central Europe of, firstly, the need for, and development of, sustainable and biological conservation practices for forest and/or woodland areas and, secondly, the lack of long-term fire history, an attempt has been made to reconstruct the fire and the forest history at several investigation sites in Germany. The overall data set gathered and analyzed has been used for on-site naturalness assessment. This latter notion is crucial for forest system conservation/restoration planning, considering the past human impact on forest dynamics. Also, in view of this past human impact on forest systems, which is well-documented for Central Europe, as occurring on a multi-millennium scale, an historical perspective perceptive that combined a long and short temporal scale of investigation was used.Nine investigation sites were selected, in order to include various and representative types of Central European forest. Therefore, the investigation sites were located in two main investigation areas. One is in Northern Germany (Schleswig-Holstein) and includes four investigation sites. The other is in Central Germany (Harz Mountains) and includes five investigation sites. Four main approaches were used. To assess the current state of the investigated site, forest stand characterization was undertaken (i.e. based on various forest attributes that concern stand structure and composition). Tree ring series were analyzed to provide insights about short-term forest tree population dynamics. Then, charcoal records from soil (combined with soil analysis) and peat sequences were qualitatively and quantitatively analyzed. These last two approaches also provide information about the past fire history. Forest current and short-term dynamics illustrated various levels of stand complexity, often corresponding to various levels of human impact that had been postulated. Eight mean site tree-ring chronologies, standardized in high and mid-frequency signal, spanning at a maximum of up to AD 1744 and at a minimum of up to AD 1923, were obtained. The insight, about the identification of events of growing changes and the correlated temporal and, if possible, spatial patterns, was discussed. Charcoal analysis provided a long-term insight about fire history. Based on 71 charcoal radiocarbon dates, it was shown on a macro-scale that there were two phases that had a greater frequency of fire - one during the transition from the late Pleistocene to the early Holocene, and one during the mid- and late Holocene. A strong human control during the most recent fire phase has been postulated. This is supported by on-site soil and peat charcoal record analysis, allowing one to point out the event of environmental changes (disturbances), at local scales. In the end, the on-site data from the various indicators were combined to assess the fire and forest history and the naturalness level of the investigated sites, based on past insights, thereby contributing to a better understanding of the present and helping to anticipate the future
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Kitchen, Stanley G. "Historic Fire Regimes on Eastern Great Basin (USA) Mountains Reconstructed from Tree Rings." Diss., CLICK HERE for online access, 2010. http://contentdm.lib.byu.edu/ETD/image/etd3396.pdf.
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Brown, Peter M., Amalava Bhattacharyya, and Santosh K. Shah. "Potential For Developing Fire Histories In Chir Pine (Pinus Roxburghii) Forest In The Himalayan Foothills." Tree-Ring Society, 2011. http://hdl.handle.net/10150/622625.
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We report on the potential for developing long-term fire histories from chir pine (Pinus roxburghii Sarg.) forests in the Western Himalayan foothills based on a preliminary study from a stand located in the state of Uttarakhand in northern India. Rings from trees collected to develop a master skeleton plot chronology were generally complacent with false rings present during most years, but were crossdatable with only minor difficulty. The oldest tree confidently crossdated back to 1886, with good sample depth (5 trees) from 1911, which helped date the fire scars in cross-sections collected from three trees. Fire frequency as determined from fire-scar dates was high, with mean and median fire intervals of 3 years from 1938 to 2006. Fires were likely from human ignitions given the prevalence of human land use in the site. Fire scars were generally recorded at false-ring boundaries and likely represent burning during the hot, dry period in May or early June before the onset of monsoon rainfall beginning in mid-June. Although only three fire-scarred trees were sampled, this preliminary assessment shows there is a potential for additional samples from other stands to develop longer-term fire histories to better understand the role of fire in the ecology and management of chir pine throughout its range in the Himalaya region.
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Smith, Kevin T., and Elaine Kennedy Sutherland. "Terminology and Biology of Fire Scars in Selected Central Hardwoods." Tree-Ring Society, 2001. http://hdl.handle.net/10150/251620.
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Dendrochronological analysis of fire scars requires tree survival of fire exposure. Trees survive fire exposure by: (1) avoidance of injury through constitutive protection and (2) induced defense. Induced defenses include (a) compartmentalization processes that resist the spread of injury and infection and (b) closure processes that restore the continuity of the vascular cambium after fire injury. Induced defenses are non-specific and are similar for fire and mechanical injury. Dissection of central hardwood species in a prescribed fire treatment area in southeastern Ohio provided an opportunity to place features seen in dendrochronological samples into their biological context. Terms for these features are proposed and further discussion is solicited.
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Nche, Charles F. "Implementing the Orwell ATM protocol over an optical fibre ring." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/14122.
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Asynchronous Transfer Mode (ATM) has emerged as a possible contender for the next generation of digital data switching system and as the fundamental transport basis for the Broadband Integrated Services Digital Network, (B-ISDN) and telecommunications in the future. ATM networks can provide a high degree of flexibility. Due to the dynamic allocation of transmission and switching resources and the absence of a physical channel structure in such a network, services are not necessarily restricted to a particular bit rate. They may work at any bit rate within the limit of the network and can also support variable bit rate connections. There is a growing need for networks to carry a greater range of traffic such as wide-band traffic (video), bursty traffic (variable bit rate video), short holding time traffic (facsimile) and low bandwidth traffic (voice). To cope with variations in demand, networks must also be capable of dynamically allocating their total capacity amongst the various traffic types. The traffic requirements can be met through the use of architectures based on Asynchronous Transfer Mode (ATM).
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Abd-el-Hamid, G. M. "An investigation of optical fibre fused couplers and ring resonators." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235380.
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Papachristos, Thalis. "Generation of microwaves using a mode locked fibre ring laser for radio-over-fibre systems." Thesis, University of Kent, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344148.
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Sida, Wichan. "Performance evaluation of the inter-connected optical ring network (ICORNet)." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366959.
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Ferreira, Vitor De Oliveira. "Firs under field extensions." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313778.
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Grissino-Mayer, Henri D. "FHX2 - Software for Analyzing Temporal and Spatial Patterns in Fire Regimes from Tree Rings." Tree-Ring Society, 2001. http://hdl.handle.net/10150/262559.
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Many studies use the temporal record of dendrochronologically-dated fire scars to document properties of fire regimes before human interference (e.g. fire suppression, logging, and agriculture) became pervasive. Such reconstructions provide vital information that can be used by land management agencies when designing and implementing fire management policies, and are especially useful for justifying the reintroduction of fire to areas where fire has long been excluded by humans. Tree-ring based fire history studies produce large quantities of data that require efficient tools for compilation, organization, and analysis. In this paper, I describe the development and use of FHX2, software comprised of individual modules designed specifically for (1) entering and archiving of fire history data, (2) creating graphs that display both temporal and spatial features of the site fire history, (3) conducting statistical analyses on fire intervals and seasonality, and (4) performing superposed epoch analysis to analyze climate /wildfire interactions. Although designed to analyze fire history, the software can be used to analyze any set of events recorded in the tree- ring record, such as growth suppressions and releases, floods, and insect outbreaks.
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Winter, Linda Ellen. "Five centuries of structural development in an old-growth Douglas-fir stand in the Pacific Northwest : a reconstruction from tree-ring records /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5480.
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Heyerdahl, Emily K., and Steven J. McKay. "Condition of Live Fire-Scarred Ponderosa Pine Trees Six Years after Removing Partial Cross Sections." Tree-Ring Society, 2001. http://hdl.handle.net/10150/251619.
Full textAbstract:
Our objective was to document the effect of fire-history sampling on the mortality of mature ponderosa pine trees in Oregon. We examined 138 trees from which fire-scarred partial cross sections had been removed five to six years earlier, and 386 similarly sized, unsampled neighbor trees, from 78 plots distributed over about 5,000 ha. Mortality was low for both groups. Although mortality was significantly higher for the sectioned trees than their neighbors (8% versus 1 %), removing a partial section did not appear to increase a tree's susceptibility to death from factors such as wind or insect activity. Specifically, the few sectioned stems that broke did so well above sampling height. Most sectioned trees (79 %) had evidence of insect activity in 1994/95, while only an additional 5% had such evidence in 2000. Mortality among sectioned trees in this study was low probably because we removed relatively small sections, averaging 7 cm thick and 8% of the tree's cross-sectional area, from large trees of a species with effective, resin-based defenses against insects and pathogens. Sampling live ponderosa pine trees appears to be a non-lethal method of obtaining information on past fire regimes in this region because it only infrequently led to their death in the early years after sampling.
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Khan, Omer Shahab. "Optical frequency shifter using stimulated Brillouin scattering in fibre optic ring resonators." Thesis, Cranfield University, 1994. http://dspace.lib.cranfield.ac.uk/handle/1826/4544.
Full textAbstract:
A fibre optic frequency shifter has been developed which generates a
heterodyne frequency that is used to facilitate electronic demodulation of
optical information. The operation of this device is analogous to an acoustooptic
device such as a Bragg cell. This frequency shifter works on the principle
of mixing two stimulated Brillouin scattering signals (generated in optical fibre
ring resonators) which have slightly different frequencies. Dual ring resonator
and single ring resonator topologies have been used. For the former system
a conversion efficiency of 16% was obtained. The beat frequency was tunable
between 218.4 MHz and 414.6 MHz for a 40'C change in temperature. A
temperature coefficient of 5+0.2 MHzK-1 was measured. The later configuration
provides a highly stable carrier frequency (11MHz) with a temperature
coefficient of 6.7+0-5 kHzK-1. A 20% conversion efficiency was obtained. This
demonstrates that this technique offers a practical, fibre efficient, low optical
power requirement method for producing a frequency shifter. One of the main
advantages of the system is that no electrical power is required to produce the
travelling acoustic wave.
A novel technique to characterize the frequency response of optical detectoramplifier
combinations, used in this project to detect these high frequencies,
is also demonstrated. The technique is based on the wavelength modulation
of a laser diode source in a path length imbalanced two-beam interferometer.
A robust configuration using a low finesse Fabry-Perot interferometer made
from birefringent optical fibre has been implemented. Measurements for
several detector circuits are presented for the frequency range DC to about 30
MHz. Results are compared with direct modulation of the laser intensity and
also with a circuit simulation programme (PSpice) and found to be in close
agreement.
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Nesbitt, John Harnisch. "Quantifying forest fire variability using tree rings Nelson, British Columbia 1700–present." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/28789.
Full textAbstract:
This study uses dendroecology to provide direct evidence of historic forest fires and their effects on stand structure and dynamics at a local scale in the montane forests in southeastern British Columbia (BC). Using tree ages and fire-scarred trees, I determined the historic variability of fires by quantifying stand dynamics in relation to past fires in the mixed-conifer forests surrounding Nelson, a wildland-urban interface community in southeastern BC. I built fire records that extended from 1642–2009 across 18 sites in the ~160,000 hectare study area. Although a watershed-level fire signal is evident, site-to-site differences in fire-scar records and stand dynamics suggest that topography and land use caused variability in the fire histories of the individual sites. Numbers of fire-scarred trees and importance values of fire-tolerant trees decreased significantly with elevation. Fire-intolerant trees were most abundant in the subcanopy across all elevations. Most strikingly, no fires were recorded since 1932 across all sites, suggesting that fire exclusion has been effective and that future stands will likely continue to diverge from historic stands by becoming more dense, more homogenous in species composition, and, as a result, more susceptible to high-severity fires.
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Brewer, Peter W., Daniel Murphy, and Esther Jansma. "Tricycle: A Universal Conversion Tool For Digital Tree-Ring Data." Tree-Ring Society, 2011. http://hdl.handle.net/10150/622638.
Full textAbstract:
There are at least 21 dendro-data formats used in dendrochronology laboratories around the
world. Many of these formats are read by a limited number of programs, thereby inhibiting
collaboration, limiting critical review of analyses, and risking the long-term accessibility of datasets. Some of the older formats are supported by a single program and are falling into disuse, opening the risk for data to become obsolete and unreadable. These formats also have a variety of flaws, including but not limited to no accurate method for denoting measuring units, little or no metadata support, lack of support for variables other than whole ring widths (e.g. earlywood/latewood widths, ratios and density). The proposed long-term solution is the adoption of a universal data standard such as the Tree-Ring Data Standard (TRiDaS). In the short and medium term, however, a tool is required that is capable of converting not only back and forth to this standard, but between any of the existing formats in use today. Such a tool is also required to provide continued access to data archived in obscure formats. This paper describes TRiCYCLE, a new application that does just this. TRiCYCLE is an open-source, cross-platform, desktop application for the conversion of the most commonly used data formats. Two open source Java libraries upon which TRiCYCLE depends are also described. These libraries can be used by developers to implement support for all data formats within their own applications.
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Algi, Fatih. "Development Of Synthetic Methodologies Directed Towards The Generation Of Five Membered Ring Allenes." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607332/index.pdf.
Full textAbstract:
Chemists have always been fascinated by the cumulated diene system of allenes with its extraordinary properties such as the axial chirality of the elongated tetrahedron and a higher reactivity than non-cumulated C-C double bonds.
The equilibrium geometry for an allene is linear with orthogonal pairs of substituents. An allene incorporated into a carbocyclic ring of nine or more carbon atoms is relatively unstrained. However, if the ring size is decreased, the linear perpendicular allene will be twisted and bent until, at some point, the energy gained by pi bonding in the two double bonds will be insufficient to offset the increased strain. Furthermore, ring constraints will exert torsion toward a planar arrangement of ligands. Therefore, one of the fundemantal questions is the influence of ring size on the barrier to pi bond rotation.
Herein we wish to unveil a review of our research related to desperately seeking for five membered ring allenes such as, cyclopenta-1,2-diene (1) and some of its
derivatives, e.g. 2, and 3. Furthermore, we will address a simple, mild and efficient method for the reduction of 1,4-benzoquinones 4 to corresponding hydroquinones 5.
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Baille, Kevin. "Fine-scale structures in Saturn's rings waves, wakes and ghosts." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4840.
Full textAbstract:
The Cassini mission provided wonderful tools to explore Saturn, its satellites and its rings system. The UVIS instrument allowed stellar occultation observations of structures in the rings with the best resolution available (around 10 meters depending on geometry and navigation), bringing our understanding of the physics of the rings to the next level. In particular, we have been able to observe, dissect, model and test the interactions between the satellites and the rings. We first looked at kilometer-wide structures generated by resonances with satellites orbiting outside the main rings. The observation of structures in the C ring and their association with a few new resonances allowed us to estimate some constraints on the physical characteristics of the rings. However, most of our observed structures could not be explained with simple resonances with external satellites and some other mechanism has to be involved. We located four density waves associated with the Mimas 4:1, the Atlas 2:1, the Mimas 6:2 and the Pandora 4:2 Inner Lindblad Resonances and one bending wave excited by the Titan -1:0 Inner Vertical Resonance. We could estimate a range of surface mass density from 0.22 ([plus or minus]0.03) to 1.42 ([plus or minus]0.21) g cm[super-2] and mass extinction coefficient from 0.13 ([plus or minus]0.03) to 0.28 ([plus or minus]0.06) cm[super2] g[super-1]. These mass extinction coefficient values are higher than those found in the A ring (0.01 - 0.02 cm[super2] g[super-1]) and in the Cassini Division (0.07 - 0.12 cm[super2] g[super-1] from Colwell et al. (2009), implying smaller particle sizes in the C ring. We can therefore imagine that the particles composing these different rings have either different origins or that their size distributions are not primordial and have evolved differently.; Using numerical simulations for the propeller formation, we estimate that our observed moonlets belong to a population of bigger particles than the one we thought was composing the rings: Zebker et al. (1985) described the ring particles population as following a power-law size distribution with cumulative index around 1.75 in the Cassini Division and 2.1 in the C ring. We believe propeller boulders follow a power-law with a cumulative index of 0.6 in the C ring and 0.8 in the Cassini Division. The question of whether these boulders are young, ephemeral and accreted inside the Roche limit or long-lived and maybe formed outisde by fragmentation of a larger body before migrating inward in the disk, remains a mystery. Accretion and fragmentation process are not yet well constrained and we can hope that Cassini extended mission will still provide a lot of information about it.; We also estimate the mass of the C ring to be between 3.7 ([plus or minus]0.9) x 10[super16] kg and 7.9 ([plus or minus]2.0) x 10[super16] kg, equivalent to a moon of 28.0 ([plus or minus]2.3) km to 36.2 ([plus or minus]3.0) km radius (a little larger than Pan or Atlas) with a density comparable to the two moons (400 kg m[super-3]). From the wave damping length and the ring viscosity, we also estimate the vertical thickness of the C ring to be between 1.9 ([plus or minus]0.4) m and 5.6 ([plus or minus]1.4) m, which is consistent with the vertical thickness of the Cassini Division (2 - 20 m) from Tiscareno et al. (2007) and Colwell et al. (2009). Conducting similar analysis in the A, B rings and in the Cassini Division, we were able to estimate consistent masses with previous works for the these rings. We then investigated possible interactions between the rings and potential embedded satellites. Looking for satellite footprints, we estimated the possibility that some observed features in the Huygens Ringlet could be wakes of an embedded moon in the Huygens gap. We discredited the idea that these structures could actually be satellite wakes by estimating the possible position of such a satellite. Finally, we observed a whole population of narrow and clear holes in the C ring and the Cassini Division. Modeling these holes as depletion zones opened by the interaction of a moonlet inside the disk material (this signature is called a "propeller"), we could estimate a distribution of the meter-sized to house-sized objects in these rings. Similar objects, though an order of magnitude larger, have been visually identified in the A ring. In the C ring, we have signatures of boulders which sizes are estimated between 1.5 and 14.5 m, whereas similar measures in the Cassini Division provide moonlet sizes between 0.36 and 58.1 m.<br>ID: 030422748; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 269-295).<br>Ph.D.<br>Doctorate<br>Physics<br>Sciences<br>Planetary Science
34
Brown, Peter M., Malcolm K. Hughes, Christopher H. Baisan, Thomas W. Swetnam, and Anthony C. Caprio. "Giant Sequoia Ring-Width Chronologies from the Central Sierra Nevada, California." Tree-Ring Society, 1992. http://hdl.handle.net/10150/262342.
Full textAbstract:
Giant sequoia was one of the first species that A. E. Douglass examined in his pioneering tree- ring research. Recent attention to sequoia, stimulated by fire history studies in sequoia groves, has resulted in new ring-width chronologies based on both recently collected tree-ring material and Douglass' original samples. The development and characteristics of four new multimillennial sequoia chronologies are described here. Three of these chronologies are based on tree-ring series from individual sites: Camp Six (347 B.C. to A.D. 1989), Mountain Home (1094 B.C. to A.D. 1989), and Giant Forest (1235 B.C. to A.D. 1988). The fourth is a composite chronology (1235 B.C. to A.D. 1989) that includes radii from the other three chronologies. Sequoia ring series are generally complacent with occasional narrow rings ("signature years"). Ring-width standardization was complicated by growth releases, many of which are known to have been caused by fires. Such growth releases confuse climatic interpretation of low-frequency signals in the time series. Ring- width series were detrended with cubic splines with 50% frequency response function at 40 years to de-emphasize low-frequency variation and were fit with autoregressive time series models to remove persistence. The resulting prewhitened chronologies contain primarily a high frequency climate signal and are useful for assessing the past occurrence of extreme drought events and for dating applications. The dating chronology originally developed by Douglass is confirmed and the annual nature of giant sequoia tree rings unequivocally verified.
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Ni, Wanmei. "An application of climatological water balance modeling to dendroclimatology in the Black Hills of South Dakota." Thesis, The University of Arizona, 1993. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1993_402_sip1_w.pdf&type=application/pdf.
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Hierlinger, Claus. "Synthesis, characterisation and optoelectronic properties of phosphorescent iridium complexes : from five to six-membered ring chelates." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16126.
Full textAbstract:
Here, the design, synthesis and characterisation and the optoelectronic properties of Ir(III) complexes for application in nonlinear optical and electroluminescent devices are described. The type of complexes varies from those of the form [Ir(C^N)2(N^N)]+ with conjugated and nonconjugated ligands (where C^N = cyclometalating ligand and N^N = neutral ligand) to those of the form [Ir(C^N^C)(N^N)Cl] (where C^N^C = tridentate tripod ligand). Chapter 1 gives an introduction into photophysics occurring in transition metal complexes and possible applications in visual displays. The background of nonlinear optical (NLO) properties and the use of transition metal complexes as NLO chromophores is described. In Chapter 2, the impact of the use of sterically congested cyclometalating ligands on the photoluminescence properties of cationic iridium(III) complexes and their performance in light-emitting electrochemical cells is investigated. Chapter 3 explores the use of electron donors on the cyclometalating ligand towards modulating the NLO properties of the complexes. Combining strongly electron-donating substituents on the C^N ligand and electron-accepting substituents on the N^N ligand results in strong NLO activity. Chapter 4 summarises a new series of cationic iridium(III) complexes bearing benzylpyridinato as cyclometalating ligands. The methylene spacer in the C^N ligands provides flexibility, resulting in two conformers. NMR studies combined with density functional theory (DFT) studies show how the fluxional behaviour is influenced by the choice of the ancillary ligand. In Chapter 5, Ir(III) complexes bearing an unusual nonconjugated bis(six-membered) tridentate tripod ligand of the form [Ir(C^N^C)(N^N)Cl] are introduced. Depending on the substitutions of the C^N^C ligand phosphorescence ranging from yellow to red was obtained. Substitution of the N^N results in a panchromatic NIR dye, suitable for DSSC applications. In Chapter 6, the concept of a nonconjugated ligand was expanded to the N^N ligand. Blue-green and sky-blue emission was obtained, demonstrating a strategy to successfully tune the emission to the blue.
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Earle, Christopher J. "Reconstructing the flow of the Sacramento River since 1560." Thesis, The University of Arizona, 1986. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0017_m_sip1_w.pdf&type=application/pdf.
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Alfaro, R. I., and R. N. MacDonald. "Effects of Defoliation by the Western False Hemlock Looper on Douglas-Fir Tree-Ring Chronologies." Tree-Ring Society, 1988. http://hdl.handle.net/10150/261809.
Full textAbstract:
Annual rings of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, which sustained 1 year of defoliation by the western false hemlock looper, Nepytia freemanii Munroe (Lepidoptera: Geometridae), showed a period of decrease in breast height ring width starting in the year that followed the damage. The magnitude of the decrease was related to the degree of defoliation: there was no ring width decrease on trees that were 0-10% defoliated; the decrease became progressively more noticeable in trees which sustained increasingly higher defoliation; and it was maximum in trees which sustained 91-100% defoliation. This period of reduction lasted 1 to 5 years and was followed by a period of above-normal growth which was related to defoliation in a similar manner: it was absent in trees 0-10% defoliated and maximum in the 91-100% tree defoliation class. Increase in defoliation caused a significant increase in index standard deviation, autocorrelation and mean sensitivity.
39
Modén, Carl S. "Micromechanics of softwoods in the transverse plane : effects on cell and annual ring scales." Doctoral thesis, KTH, Lättkonstruktioner, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9604.
Full textAbstract:
Transverse mechanical properties of wood are important in many practial applications and an interesting scientific subject. A very low transverse shear modulus has been identified in spruce, which causes large strain concentrations in wood structures. In this thesis, experimental characterization of local density variations as well as local strain fields are carried out using the SilviScan apparatus and digital speckle photography, respectively. This is combined with micromechanical modeling based on hexagonal wood cells in combination with finite element analysis. Problems addressed include the moduli in the transverse plane, including variations at the scale of individual annual rings. The relative importance of cell wall bending and stretching deformation mechanisms is analysed as a function of wood cell geometry, relative density and direction of loading (radial, tangential and shear). Transverse anisotropy is also analyzed, including its dependency of earlywood and latewood characteristics. The wood cell shape angle variation and density effects are sufficient to explain transverse anisotropy in softwoods (no ray effects), and the influence of earlywood/latewood ratio is explained. As a practical test method for shear modulus measurements, an off-axis compression test with full-field strain determination is proposed. The advantage is a simple fixture and large region of representative strain required for a heterogeneous material such as wood. As an alternative, the single cube apparatus (SCA) for shear tests is evaluated. The SCA is used to determine the shear strain distribution within the annual rings. Based on the density distribution of the shear test specimen and a micromechanics model, a finite element model is developed, and predictions are compared with the measured shear strains. The agreement between predicted and measured shear strains at the annual ring scale are remarkably good. It shows that the low GRT of spruce is due to the low earlywood density and the large cell wall bending deformation resulting from shear loading. Furthermore, it illustrates the need for improved understanding of annual ring scale effects. For example, fairly low transverse global loads will lead to lage local shear strains.<br>Transversella mekaniska egenskaper hos trä är viktiga i många praktiska tillämpningar och är av vetenskapligt intresse. Gran har exemplevis mycket låg transversell skjuvmodul, vilket leder till stora lokala töjningskoncentrationer i trästrukturer. I den här avhandlingen utförs experimentella mätningar av densitetsfördelning och lokal töjningsfördelning med hjälp av SilviScan utrustning (röntgen) och digital speckelfoto grafi (DSP). Det kombineras med mikromekanisk modellering med hexagonala cellmodeller som utgångspunkt, ibland i kombination med finita elementberäkningar. Transversella moduler bestäms liksom töjningseffekter på skalan individuella årsringar. Den relativa betydelsen av böjning och sträckning av cellväggen analyseras som funktion av relativ densitet och belastningsriktning (radiell, tangentiell och skjuvning). Stor andel böjdeformation ger låg modul och proportionerna mellan de båda mekanismerna styr graden av anisotropi. Transversell anisotropi analyseras därför, inklusive dess beroende av karakteristiken hos vårved och sommarved. Formvinkeln på vedcellen och inverkan av densitet är tillräckliga för att förklara graden av anisotropi (utan inverkan från märg- strålar). Inverkan av förhållandet mellan mängden vårved och sommarved på anisotropin analyseras särskilt. En enkel tryckbelastningsmetod (“off-axis metod”) används för att bestämma transversell skjuvmodul hos trä. Metoden kombineras med DSP. Fördelen är en enkel fixtur i kombination med det stora område av ren skjuvdeformation som uppstår i provstaven. Som ett alternativ utvärderas också en metod baserad på kubiskt prov (SCA). Metoden används för att bestämma lokala skjuvtöjningar på skalan individuella årsringar. Baserat på densitetsfördelningen i provet och en mikromekanisk modell så utvecklas en finita element-modell. Den utnyttjas för att beräkna lokala skjuvtöjningar. Jämförelsen mellan beräkningar och uppmätta skjuvtöjningar ger enastående god överensstämmelse. Det visar att den låga skjuvmodulen för gran orsakas av låg densitet i kombination med att böjning av cellväggarna dominerar som deformationsmekanism. Det illustrerar också att vi behöver förbättra vår förståelse för deformationsfält på årsringsnivå. En praktisk konsekvens är t ex att relativt låga globala laster ger upphov till mycket hög lokal skjuvdeformation.<br>QC 20100830
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Schmidberger, Michael J. [Verfasser], Nicolas Y. [Akademischer Betreuer] Joly, and Ben [Akademischer Betreuer] Fabry. "Nonlinear Dynamics in Photonic Crystal Fibre Ring Cavities / Michael J. Schmidberger. Gutachter: Nicolas Y. Joly ; Ben Fabry." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2014. http://d-nb.info/1065045115/34.
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Simpson, Iain David. "Synthesis of highly functionalised five membered rings by photoreactions of pyridinium salts." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326910.
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Holmes, Richard L., Rex K. Adams, and Harold C. Fritts. "Tree-Ring Chronologies of Western North America: California, Eastern Oregon and Northern Great Basin with Procedures Used in the Chronology Development Work Including Users Manuals for Computer Programs COFECHA and ARSTAN." Laboratory of Tree-Ring Research, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/304672.
Full textAbstract:
Well replicated tree-ring samples were collected, dated
and measured for California west of the Sierra Nevada,
eastern Oregon and the northern Great Basin. A computer
program was developed and used to check crossdating quality.
Another computer program to generate and analyze tree-ring
chronologies was evaluated, further developed cooperatively
and used to produce chronologies for the dated site
collections.
This report contains these site chronologies in three
versions along with site descriptions and chronology
statistics. Users manuals are included for the two computer
programs. The effect on a chronology of poor crossdating is
discussed, and a study of standardization of tree-ring
measurement series is reported. Some new techniques are
described for processing tree-ring samples.
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Zhang, Qibin. "Modern and late Holocene climate-tree-ring growth relationships and growth patterns in Douglas-fir, coastal British Columbia, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ52780.pdf.
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Heyerdahl, Emily K., and Steven J. McKay. "Condition Of Live Fire-Scarred Ponderosa Pine Eleven Years After Removing Partial Cross-Sections." Tree-Ring Society, 2008. http://hdl.handle.net/10150/622566.
Full textAbstract:
Our objective is to report mortality rates for ponderosa pine trees in Oregon ten to eleven years
after removing a fire-scarred partial cross-section from them, and five years after an initial survey of post-sampling mortality. We surveyed 138 live trees from which we removed fire-scarred partial crosssections in 1994/95 and 387 similarly sized, unsampled neighbor trees of the same species. These trees were from 78 plots distributed over about 5,000 ha at two sites in northeastern Oregon. The annual mortality rate for sectioned trees from 1994/95 to 2005 was 3.6% compared to 2.1% for the neighbor trees. However, many of the trees that died between 2000 and 2005 were likely killed by two prescribed fires at one of the sites. Excluding all trees in the plots burned by these fires (regardless of whether they died or not), the annual mortality rate for sectioned trees was 1.4% (identical to the rate from 1994/95 to 2000) compared to 1.0% for neighbor trees. During these fires, a greater proportion of sectioned trees died than did catfaced neighbor trees (80% versus 64%) but the difference was not significant.
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Ellis, Andrew. "All optical networking beyond 10 Gbits/s OTDM networks based on electro-optic modulators and fibre ring lasers." Thesis, Aston University, 1997. http://publications.aston.ac.uk/7978/.
Full textAbstract:
This thesis examines options for high capacity all optical networks. Specifically optical time division multiplexed (OTDM) networks based on electro-optic modulators are investigated experimentally, whilst comparisons with alternative approaches are carried out. It is intended that the thesis will form the basis of comparison between optical time division multiplexed networks and the more mature approach of wavelength division multiplexed networks. Following an introduction to optical networking concepts, the required component technologies are discussed. In particular various optical pulse sources are described with the demanding restrictions of optical multiplexing in mind. This is followed by a discussion of the construction of multiplexers and demultiplexers, including favoured techniques for high speed clock recovery. Theoretical treatments of the performance of Mach Zehnder and electroabsorption modulators support the design criteria that are established for the construction of simple optical time division multiplexed systems. Having established appropriate end terminals for an optical network, the thesis examines transmission issues associated with high speed RZ data signals. Propagation of RZ signals over both installed (standard fibre) and newly commissioned fibre routes are considered in turn. In the case of standard fibre systems, the use of dispersion compensation is summarised, and the application of mid span spectral inversion experimentally investigated. For green field sites, soliton like propagation of high speed data signals is demonstrated. In this case the particular restrictions of high speed soliton systems are discussed and experimentally investigated, namely the increasing impact of timing jitter and the downward pressure on repeater spacings due to the constraint of the average soliton model. These issues are each addressed through investigations of active soliton control for OTDM systems and through investigations of novel fibre types respectively. Finally the particularly remarkable networking potential of optical time division multiplexed systems is established, and infinite node cascadability using soliton control is demonstrated. A final comparison of the various technologies for optical multiplexing is presented in the conclusions, where the relative merits of the technologies for optical networking emerges as the key differentiator between technologies.
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Sawyer, James R. "Rhodium-catalyzed carbocyclization reactions for the synthesis of five- and six-membered rings." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3319834.
Full textAbstract:
Thesis (Ph.D.)--Indiana University, Dept. of Chemistry, 2008.<br>Title from PDF t.p. (viewed on May 13, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4763. Adviser: P. Andrew Evans.
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FREDDITORI, MATTIA. "Asymmetric synthesis of chiral oxygenated five-membered rings: from mechanism to total synthesis." Doctoral thesis, Università degli studi di Pavia, 2017. http://hdl.handle.net/11571/1203269.
Full textAbstract:
Nell’ambito del progetto è stata sviluppata una strategia altamente stereoselettiva per l’ottenimento di nuclei tetraidrofuranici 3-idrossi-trans-2,5 disostituiti, attraverso la desimmetrizzazione di substrati meso mediante eterificazione allilica asimmetrica Pd(0) catalizzata.
Il metodo è stato poi sfruttato per la realizzazione di un approccio alla sintesi di un oxilipide marino bioattivo.
Infine, sono stati compiuti studi sintetici per la generazione di sistemi γ-butirrolattonici trisostituiti presenti in alcuni lignani ad attività antiossidante.<br>Within the project, a highly stereoselective strategy toward 3-hydroxy-trans-2,5-disubstituted THF cores has been developed. Such approach, is based on the Pd (0)-catalyzed asymmetric allylic etherification of meso diol systems. The method was then exploited for the realization of an approach to the synthesis of a bioactive marine oxylipide. Finally, synthetic studies have been performed, for the generation of trisubstituted γ-butyrolactone cores, present in some lignans with antioxidant activity.
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Guiterman, Christopher, and Christopher Guiterman. "Climate and Human Drivers of Forest Vulnerability in the US Southwest: Perspectives from Dendroecology." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/622981.
Full textAbstract:
The ongoing drought in the US Southwest (SW) has led to particularly large and severe wildfires, tree die-off events, insect outbreaks, and increased forest stress levels. These disturbances underscore the vulnerabilities of SW dry conifer forests to climate change and past land-uses. Climate projections show a clear upward trend in regional temperatures, which will lead to accelerated heat-related stressors and disturbances in the coming decades. Already, more than 20% of the dry conifer forests of the SW have been severely impacted. This number is likely to grow, but we lack a clear picture of where, when, and to what degree other forest areas will be affected. Here, I apply dendroecological methods to evaluate patterns and processes that might determine greater or lesser vulnerability in dry conifer forests. Much of this work stems from critical concerns voiced by the Navajo Forestry Department (NFD). Long-term and representative data are necessary for the NFD, as they are responsible for closely managing over 250,000 hectares of forests and woodlands for the traditional products and ecosystem services that their forests provide for the Navajo people. The first study takes a multi-century perspective on changing fire regimes across Navajo forests, and places current forest structure and recent severe events in a long-term context. We found that surface fires were frequent across the landscape from at least the late-1500s until 1880. Navajo settlement of the area began to affect the fire regimes with added small fires in some areas beginning in 1700. By 1832, the rise of traditional pastoralist practices and transhumant migrations reduced fire activity in areas of greater use. Conditions changed following the establishment of the Navajo reservation in 1868, as livestock herds grew rapidly and initiated a near-synchronous and widespread collapse of fire regimes across the study area by 1880. The legacies of this change in land use are greater forest densities and higher fuel loads in some areas, raising the vulnerability of the forest to more severe fires. The second study assesses one of the most dramatic long-term consequences of recent high-severity fires in the SW, the rapid post-fire transition of dry conifer forest to oak-dominated shrubfields. To assess probable successional trajectories and interactions with climate change of recently converted forests, we reconstructed the age structures and fire regimes of some of the largest and oldest shrubfields in the Jemez Mountains of northern New Mexico. We found that shrubfields are a resilient configuration to drought and fire, historically burning at the same rates and under similar climate as dry conifer forests. Dense shrubfields pose a significant challenge to conifer recruitment from competition effects, with our sites persisting for over 100 years in the absence of burning and through periods of favorable climate to conifers. Given future warming favoring oak over pine, and projected trends in fire activity and high-severity fire behavior, we expect much more forest area to convert to shrubfield, especially in the absence of restoration efforts to reduce crown fire potential.Finally, we evaluate landscape-scale variability in tree growth response to regional climate across the Navajo forest. Projections of climate-induced forest decline often omit upper-elevation and mesic sites because they are not represented in regional tree-ring chronology networks. We found that these stands had much lower response to 20th century droughts than mid to lower elevation stands, and that targeted tree-ring sites are consistently more correlated with regional climate. However, as temperature-driven atmospheric moisture demand has remained above average since ~1997 in the study area, the upper-elevation trees are now nearly as responsive to regional climate as lower elevation xeric sites, probably due to increased moisture limitations. Recent warming has thus synchronized tree growth to an unprecedented extent across this large landscape and regionally.
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Pittman, Eddie LaReece. "Computed NMR shielding values of unsaturated five-membered-heterocyclic ring compounds and their benzo-analogs as a measure of aromaticity." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-2/r1/pittmane/eddiepittman.pdf.
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Nin, Hill Alba. "Conformational catalytic itineraries of five- and six-membered sugar rings in enzymatic and superacid media." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/669885.
Full textAbstract:
Carbohydrates were early considered important for energy storage and structural support for living organisms. It was not until a few decades ago that scientist discovered that they are also involved in much more complex mechanisms, such as modulating protein structures, locating and signalling in multicellular systems and cell-cell recognition, including bacterial and virus infections and in some aspects of cancer. Consequently, carbohydrates are getting more recognition, being used in drug delivery strategies, vaccines and new therapeutics for treating many types of diseases. Carbohydrates come in many stereochemistries, configurations and conformations which converts them into very complex molecules to study. The vast amount of carbohydrate-based structures in nature needs a larger number of enzymes responsible of their degradation, synthesis and possible modifications. These are named as carbohydrate-active enzymes (CAZymes), which include glycoside hydrolases, glycosyltransferases, polysaccharide lyases and carbohydrate esterases. This Thesis focuses on glycosyl hydrolases (GHs), which are responsible for the hydrolysis of glycosidic bonds. The possible sugar ring conformations that carbohydrates can adopt in the enzyme active sites during catalysis depends on the distinct active site topologies found for the more than 150 GH families. Each GH (or each family of GHs) hosts a particular catalytic conformational itinerary of the corresponding carbohydrate substrate. Understanding these itineraries is of great importance when designing selective inhibitors, as some of the most powerful inhibitors mimic the structure and properties of the transition state (TS) of the hydrolysis reaction. Molecular mechanisms and catalytic conformational itineraries of GHs can be investigated with both experimental and computational approaches. Typically, an initial structure of the GH enzyme is needed to further perform computational analyses to elucidate the electronic and conformational changes along the catalytic itinerary of the carbohydrate substrate. In this Thesis we will focus on two GHs of biochemical and biotechnological relevance, which the catalytic conformational itineraries were still unknown, the β-D-galactocerebrosidase (GALC) and α-L-arabinofuranosidase Aspergillus kawachii abfB (AkAbfB). These GHs act on carbohydrates formed by five and six-membered rings (derivatives of β-D-galactose and α-L-arabinose, respectively). Additionally, and motivated by recent NMR experiments of isolated glycosyl cations, we analyse the properties of five-and six- membered glycosyl cations in different environments; in vacuum, in superacid media and on- enzyme.<br>Els carbohidrats no només són una eina d’emmagatzematge d’energia i de suport estructural dels éssers vius, sinó també actuen en mecanismes molt més complexos, com la localització i senyalització en sistemes multicel·lulars i el reconeixement entre cèl·lules, incloent-hi infeccions causades per bacteris i virus. Consegüentment, s’està donant més reconeixement als carbohidrats, utilitzant-los dins del camp dels fàrmacs per tractar molts tipus de malalties. Els carbohidrats presenten estereoquímiques, configuracions i conformacions molt variades, cosa que els converteix en unes molècules molt complexes d’estudiar. Aquesta gran varietat fa que existeixi també una gran quantitat d’enzims, anomenats “enzims actius en carbohidrats”, que s’encarreguen de la seva degradació, la seva síntesis i les seves possibles modificacions. Aquesta Tesi s’ha centrat en les glicosidases, responsables d’hidrolitzar els enllaços glicosídics. Les possibles conformacions que poden adoptar els anells de sucre en el centre actiu d’aquests enzims depenen de les diferents topologies que es troben en les més de 150 famílies de glicosidases. Cada glicosidasa opera amb un itinerari conformacional particular del corresponent substrat. El coneixement d’aquests itineraris és de gran importància en el disseny selectiu d’inhibidors, ja que alguns dels inhibidors més potents imiten l’estructura i les propietats de l’estat de transició de la reacció d’hidròlisi. Els mecanismes moleculars i els itineraris conformacionals de les glicosidases es poden investigar tant amb mètodes experimentals com amb mètodes computacionals. Usualment, es necessita una estructura inicial d’una glicosidasa per poder després fer anàlisis computacionals per a elucidar els canvis electrònics i conformacionals que pateix el sucre al llarg de l’itinerari catalític. En aquesta Tesi, ens centrarem en dues glicosidases de rellevància bioquímica i biotecnològica, de les quals l’itinerari conformacional era encara desconegut: la β-galactocerebrosidasa (GALC) i l’α-L-arabinofuranosidasa Aspergillus kawachii abfB (AkAbfB). Aquestes glicosidases actuen en carbohidrats formats per anells de cinc i de sis àtoms de carboni (derivats de la β-D-galactosa i l’α-L- arabinosa, respectivament). Per últim, i motivat per experiments recents de caracterització de cations de glicosil en medi superàcid, s’analitzen aquests cations, tant per a sucres de cinc com de sis àtoms de carboni en diferents entorns: en el buit, en medi superàcid i dins d’un enzim.