Dissertations / Theses on the topic 'Tumor Size Growth Rate'

Glioblastoma multiforme (GBM) is a destructive brain cancer that results in death 12 to 15 months after diagnosis. The purpose of this retrospective study was to determine if variations in tumor size at diagnosis, treatment options, and survival rate occur in GBM patients living in urban and rural areas of the United States. Using the behavior model of health services as the theoretical framework, this study used secondary data sets of GBM cases reported from 1988 to 2011 from the Surveillance, Epidemiology, and End Results program. Tumor size was measured in millimeters; treatment was evaluated by ascertaining the number of GBM patients who had surgical resection of their tumors, radiation, and chemotherapy; and survival rate was evaluated using Cox Regression analysis. With a sample size of 33,202 cases, data were examined using descriptive and multivariable analyses with SPSS. Results showed statistically significant differences in tumor size at diagnosis in rural patients compared to urban patients (p = 0.0085; p = 0.018), more urban patients were treated with radiation compared to rural patients (p < 0.001), and rural patients had poorer survival rates than urban patients (p < 0.001). Finally, when controlling for region, race, age, gender, education, and income, longer survival time was associated with urban status, female cases, and higher family income (p < 0.0001), and greater age was associated with reduced survival time (p < 0.0001). Study results could promote positive social change by identifying predictive variables associated with health outcomes of GBM patients. It may also educate providers on the risk of rurality of patients diagnosed with GBM, and inform lawmakers responsible for the creation of healthcare policy and the equitable allocation of healthcare resources.

This thesis is about firm dynamics, and relates to the size and growth-rate distribution of firms. As such, it consists of an introductory and four separate chapters. The first chapter concerns the size distribution of firms, the two subsequent chapters deal more specically with high-growth firms (HGFs), and the last chapter covers a related topic in distributional estimation theory. The first three chapters are empirically oriented, whereas the fourth chapter develops a statistical concept.<br><p>QC 20130215</p>

[EN] The aim of this thesis was to evaluate the productive performance of a rabbit line (OR-LS) selected by ovulation rate during first 6 generations (period 1), and later by ovulation rate (OR) and litter size (LS) during 11 generations using independent culling levels (Period 2). Genetic parameters, direct response for OR and LS and the correlated response for embryo (ES), foetal (FS) and prenatal survival (PS) were estimated. Also, the correlated response on growth rates (GR), weaning (WW) and marketing weight (MW) were estimated. The objective of chapter 3 was to estimate the genetic parameters of the productive traits and the response to selection by OR and LS of OR-LS line. For traits analysis, Bayesian methods were used. Heritability values of litter size traits were low, 0.10, 0.07, 0.07 and 0.07 for litter size, number of born alive (NBA), number of kits at weaning (NW) and marketing (NM), respectively. Heritability for OR was moderate (0.25), while it was low (0.13 and 0.14) for number of implanted embryos (IE) and number of live foetuses at 12 days of gestation (LF12), respectively. Low heritability values for survival traits were found, 0.09 for embryo survival (ES), 0.16 for foetal survival (FS) and 0.14 for prenatal survival (PS). In the second period, after 11 generations of selection by OR and LS, a genetic response of 0.17 kits per generation for LS was achieved. This response was higher than the obtained in period 1 (0.07 kits per generation), in which just selection by OR was performed. The opposite effect was found for OR; the highest response for OR appeared in the first period (0.24 ova per generation) versus the second period (0.17 ova per generation). This reduction in OR response can be due to the decrease in selection differential during the second period of selection. Since high genetic correlations were obtained for LS and other litter size traits, a positive correlated response was observed for NBA, NW and NM (0.12, 0.12 and 0.11 kits per generation, respectively) in the second period. In the first period, no correlated response on ES was observed and a decrease in FS (-0.04) was found. Nevertheless, in the second period a correlated response on PS appeared due to an improvement in both ES (0.04) and FS (0.03). Summarizing, the improvement in litter size in the second period is due to an increase in ovulation rate as well as an increase in prenatal survival. The objective of chapter 4 was to study the correlated response on growth traits in the OR-LS line in both periods of selection, the selection by OR during six generations and the selection by independent levels by OR and LS during 11 generations. The heritability estimates were low for weaning weight (WW), marketing weight (MW) and growth rate (GR), 0.09, 0.13 and 0.14, respectively. The estimated genetic correlations of WW, GR and MW with LS were around zero and with OR were positive and from low (0.19) to moderate (0.38). The positive moderate genetic correlation estimated between OR and MW could explain the correlated response found in MW. Correlated response on WW could be explained by positive and high genetic correlation between MW and WW. The aim of chapter 5 was to investigate magnitude and timing of embryo and early foetal survival in females with high OR using hormonal treatment as a model for selection by OR. Two groups of females (treated and untreated) were used. Treated females were injected with 50 IU eCG 48 hours before mating. Females were slaughtered at day 18 of gestation. OR, IE, LF12 and LF18 were recorded. Besides, ES (IE/OR), FSLF18 (LF18/IE), FSLF18/LF12 (LF18/LF12) and PSLF18 (LF18/OR) were estimated. Treated females had a higher OR than untreated females. According to the previous results for OR and LF18, treated females showed a lower survival rate from ovulation to 18 d of gestation. Treated females also had lower embryo and foetal survival. Main difference in foetal survival appeared from day 12 to 18 of gestation.<br>[ES] El objetivo de esta tesis fue evaluar el tamaño de camada de una línea de conejo seleccionada por tasa de ovulación durante las primeras seis generaciones (periodo 1) y después por tasa de ovulación (OR) y tamaño de camada (LS) durante 11 generaciones mediante el método de niveles independientes (periodo 2). Se estimaron los parámetros genéticos, así como la respuesta en OR y LS y la respuesta correlacionada en los caracteres reproductivos (capítulo 3). Además, se evaluó la respuesta correlacionada en los caracteres de crecimiento (capítulo 4); peso al destete (WW), peso al sacrificio (MW) y ganancia de peso entre el destete y el sacrificio (GR). Para el análisis de los caracteres se utilizaron métodos bayesianos. El objetivo del capítulo 3 fue estimar los parámetros genéticos de los caracteres reproductivos y la respuesta a la selección. Los valores de heredabilidad de los caracteres del tamaño de camada fueron bajos (alrededor de 0.10). La heredabilidad estimada para OR fue moderada (0.25), mientras que fue baja para el número de embriones implantados (IE) y el número de fetos vivos a los 12 días de gestación (LF12). Se obtuvieron valores bajos de heredabilidad; 0.09 para la supervivencia embrionaria (ES), 0.16 para la supervivencia fetal (FS) y 0.14 para la supervivencia prenatal (PS). En el periodo 2, se obtuvo una respuesta genética de 0.17 gazapos por generación para LS. Esta respuesta fue mayor que la obtenida en el periodo 1. En el caso de la tasa de ovulación, la mayor respuesta en OR se obtuvo en el periodo 1 (0.24 óvulos por generación) versus (0.17 óvulos por generación) en el periodo 2. Esta reducción en la respuesta de OR se puede atribuir a la disminución del diferencial de selección durante el período 2 de selección. De acuerdo con la alta correlación genética entre LS y otros caracteres del tamaño de camada, también se observó una respuesta correlacionada positiva en el número de nacidos vivos (NBA), destetados (NW) y comercializados (NM); 0.12, 0.12 y 0.11 gazapos por generación, respectivamente, en el segundo periodo. En el primer periodo no se observa respuesta correlacionada en la SE y se produce una disminución de la SF (-0.04). Sin embargo, en el segundo periodo se produce una respuesta correlacionada positiva en la SP que se debe a una mejora de la SE (0.04) y SF (0.03). En resumen, la mejora del tamaño de camada en el segundo periodo se debe tanto a un aumento de la tasa de ovulación como a un aumento de la supervivencia prenatal. El objetivo del capítulo 4 fue estudiar la respuesta correlacionada en los caracteres de crecimiento en esta línea. Las estimas de heredabilidad fueron bajas para los caracteres WW (0.09), MW (0.13) y GR (0.14). Las correlaciones genéticas estimadas de LS con WW, MW y GR fueron cercanas a cero; con la tasa de ovulación, las correlaciones fueron positivas y variaban de bajas a moderadas (de 0.19 a 0.38). La correlación genética moderada entre OR y MW podría explicar la respuesta correlacionada observada en MW. La alta correlación entre MW y WW podría explicar la respuesta correlacionada obtenida para WW. Finalmente, el objetivo de capítulo 5 fue estudiar en hembras con alta tasa de ovulación en qué momento se producen las mayores pérdidas fetales y cómo se ve afectado el desarrollo fetal. Para ello, de un total de 51 hembras, 24 hembras fueron pinchadas con 50 UI de eCG 48 horas antes de la cubrición para aumentar la tasa de ovulación. Las hembras fueron sacrificadas a los 18 días de gestación. Se registró OR, IE y el número de fetos vivos a los 12 y 18 días de gestación (LF18). Las hembras tratadas tuvieron una tasa de ovulación mayor que las no tratadas. De acuerdo con los resultados obtenidos para OR y LF18, las hembras tratadas mostraron una supervivencia más baja desde la ovulación hasta los 18 días de gestación y tuvieron una menor supervivencia embrionaria y fetal. Las principales diferencias en l<br>[CAT] L'objectiu d'esta tesi va ser avaluar la millora de la grandària de ventrada d'una línia de conill seleccionada per tasa d'ovulació durant les primeres sis generacions (període 1) i després per tasa d'ovulació (OR) i la grandària de ventrada (LS) durant 11 generacions per mitjà del mètode de nivells independents (període 2). Es van estimar els paràmetres genètics, així com la resposta en OR i LS i la resposta correlacionada en caràcters reproductius (capítol 3). A més, es va estudiar la resposta correlacionada en els caràcters de creixement (capítol 4); pes al deslletament (WW), pes al sacrifici (MW) i guany de pes entre el deslletament y el sacrifici (GR). Per a l'anàlisi dels caràcters es van utilitzar mètodes bayesians. L'objectiu del capítol 3 va ser estimar els paràmetres genètics dels caràcters reproductius i la resposta a la selecció. Els valors d'heretabilitat dels caràcters de la grandària de ventrada van ser baixos (al voltant de 0.10). L'heretabilitat estimada per a OR va ser moderada (0.25), mentres que va ser baixa per al nombre d'embrions implantats (IE) i el nombre de fetus vius als 12 dies de gestació (LF12). Es van obtindre valors baixos d'heretabilitat; 0.09 per a ES, 0.16 per a FS i 0.14 per a PS. En el període 2, es va obtindre una resposta genètica de 0.17 llorigons per generació per a LS. Esta resposta va ser major que l'obtinguda en el període 1. En el cas de la tasa d'ovulació, la major resposta per a OR va ser en el primer període (0.24 òvuls per generació) versus (0.17 òvuls per generació) en el període 2. Esta reducció en la resposta d'OR es pot atribuir a la disminució del diferencial de selecció durant el període 2 de selecció. Donada l'alta correlació genètica entre LS i altres caràcters de la grandària de ventrada, també es va observar una resposta correlacionada positiva en el nombre de nascuts vius (NBA), deslletats (NW) i comercialitzats (NM); 0.12, 0.12 i 0.11 llorigons per generació, respectivament, en el segon període. En el primer període no s'observa resposta correlacionada en la SE i es produeix una disminució de la SF (-0.04). No obstant això, en el segon període es produeix una resposta correlacionada en la SP que es deu a una millora de la SE (0.04) i SF (0.03). En resum, la millora de la grandària de ventrada en el segon període es deu tant a un augment de la tasa d'ovulació com a un augment de la supervivència prenatal. L'objectiu del capítol 4 va ser estudiar la resposta correlacionada en els caràcters de creixement en aquesta línia. Les estimes d'heretabilitat van ser baixes per als caràcters WW (0.09), MW (0.13) i GR (0.14). Les correlacions genètiques estimades de LS amb WW, MW i GR van ser pròximes a zero; amb la tasa d'ovulació, les correlacions van ser positives i variaven de baixes a moderades (de 0.19 a 0.38). La correlació genètica moderada entre OR i MW podria explicar la resposta correlacionada trobada per a MW. D'altra banda, l'alta correlació entre MW i WW podria explicar la resposta correlacionada obtinguda per a WW. Finalment. l'objectiu del capítol 5 va ser estudiar en femelles amb alta tasa d'ovulació en quin moment es van produir les majors pèrdues fetals i com es veu afectat el desenvolupament fetal. Per a això, d'un total de 51 femelles, 24 femelles van ser punxades amb 50 UI d'eCG 48 hores abans del cobriment per a augmentar la tasa d'ovulació. Les femelles van ser sacrificades al 18 dies de gestació. Es va registrar OR, IE i el nombre de fetus vius al 12 i 18 dies de gestació (LF18). Les femelles tractades van tindre una tasa d'ovulació major que les no tractades. D¿acord als resultats obtinguts per OR i LF18, les femelles tractades van mostrar una supervivència més baixa des de l'ovulació fins als 18 dies de gestació i van tindre una menor supervivència embrionària i fetal. Les principals diferències en la supervivència fetal van aparèixer entre els dies 12 i 18 de gestaci<br>Yehia Badawy Elmoghazy, A. (2016). SELECTION FOR OVULATION RATE AND LITTER SIZE IN RABBITS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/73265<br>TESIS

Morley, S. A. (1998). Environmental and parental influences on the size of herring larvae. Ph.D. thesis submitted to the University of Liverpool for the degree of Doctor of Philosophy Investigations were carried out into the effects of mean egg dry weight and incubation temperature on the size of larvae from four N.E. Atlantic herring stocks (Buchan, Manx, Clyde and Celtic Sea). Hatching characterisitics (length, weight and yolk volume) of Buchan, Manx and Clyde herring were investigated. The time of hatching was inversely related to incubation temperature, although there was some variation between experiments in the date of peak hatching. The total length of larvae increased through the hatching period. In all experiments mean egg dry weight per female was strongly related to the average length, weight and yolk volume of larvae at hatching. The same regression model could be applied to all stocks. There were, however, stock-specific responses of hatching characteristics to incubation temperature although a reduction in length at hatching at higher temperatures was the most consistent response. Development at low temperature resulted in a modification of the length-weight relationship; larvae of the same weight were longer at lower temperatures. Both the increase in length of larvae during the hatching period and the variation in the timing of peak hatching have implications for the comparison of larvae hatching at different temperatures. The otoliths of Manx herring larvae [from "large" (> 0.33mg mean dry weight) and "small" «0.2Smg mean dry weight) eggs] were marked with either alizarin complexone or calcein so that larvae from pairs of large and small egg batches could be reared under identical conditions (at both 10 and I3.S0C) and relative growth monitored. Within each rearing tank large eggs generally produced larger larvae at hatch (length and weight) with higher growth rates (both weight and length specific). There were significant differences both between eggs from different females and between rearing tanks that confounded the comparisons between rearing temperatures. Fultons Condition factor is not thought to be a good measure of nutritional condition of herring larvae smaller than ISmm total length but may be used as a relative measure of body reserves (ReF) and give an indication of ability to withstand periods of poor feeding. This is indicated by a period of high mortality of larvae hatched from small eggs at 10°C, which corresponded with the time period when these larvae had the lowest body reserves. Video recording of the foraging behaviour of laboratory reared herring larvae was used to investigate differences between the feeding strategies of groups of larvae of the same size but different ages, i.e. fast and slow growers. Slow growing larvae searched larger areas, thus expending more energy, than fast growing larvae, but there was no difference in food acquisition. The difference in behaviour tended to increase through development A simple energetics calculation suggested that approximately 50% of the difference in growth rate could be explained by the extra swimming costs of slower growing larvae. The size of Celtic Sea and Manx herring eggs were experimentally reduced in order to investigate if the volume of yolk in each egg determines the size of hatching larvae. Length at hatch was determined by the volume of yolk in each egg but body weight was not. The development and chemical composition of embryos and larvae needs to be investigated in a further series of experiments. All results are discussed in terms of the influence of larval size on survival.

We initiated bait station surveys for black bears in southwestern Virginia in 1999. Bait station surveys are intended to be used as an index to follow bear population trend over time. We compared the bait station visitation (black bear visitation) to black bear harvest and mast surveys 1999 = 2002. The mean bait station visitation rate during 1999 - 2002 was 15.3% (SE = 2.89, n = 4). The number of bears harvested in the 3 counties that also had bait station surveys was 48 (31 males, 17 females), 59 (44 males, 15 females), 45 (32 males, 13 females), and 43 (26 males, 17 females) in 1999, 2000, 2001, and 2002, respectively. Harvest of males and females differed (n = 2, F = 19.44, df = 1, P = 0.0045). Bait station visitation and female harvest had a strong functional relationship with a negative slope (n = 4, r = -0.78, P = 0.22). The strongest relationship was between male harvest and total harvest (n = 4, r = 0.97, P = 0.03). Mean index to mast production for 1999 - 2002 was 2.3 (range 1.5 - 3.1), 2.7 (range 1.8 - 3.4), 2.3 (range 1.6 - 3.6), and 1.6 (range 1.2 - 2.4), respectively. The overall summary for mast production for the same years was described as fair, good, fair, and poor to fair. Mast production was significantly different between years (n = 4, F = 3.44, df = 3, P = 0.0326), and soft and hard mast production appeared to be above average in 2000. This corresponded with the lowest visitation (10.2%) of the 4 years. There was no correlation between bait station visitation and mast production (n = 4, r = 0.11, P = 0.87). Since 1998, the annual bear harvest in Virginia has exceeded 900 individuals (with the exception of 824 in 2001), and peaked in 2000 when 1,000 bears were harvested. Though harvest rates were high, a reliable population estimate did not exist for black bears in Virginia. We estimated population size, growth rate, and minimum viable population size using data collected between 1995-2000. We used Jolly-Seber, direct recovery, and minimum population size methods to estimate population size. The Jolly-Seber method estimate of adult female density was 0.23-0.64 bears/km2, and 0.01 bears/km2 for adult males. We estimated a density of 0.09-0.23 bears/km2 for all sex and age classes using direct recovery data. Using minimum population size, we found adult female density was higher than any other sex or age class (n = 6, t = 2.02, df = 40, P < 0.0001) with an average density of 0.055 adult females/km2. We used mark-recapture data collected from 148 individual bears (96 males:52 females) captured 270 times in program MARK to estimate survival using recapture, dead recovery, and Burnham's combined models. Adult females had the highest survival rate of 0.84-0.86, while yearling males had the lowest with 0.35. Using direct recovery data, adult females again had the highest survival rate with 0.93 (0.83-1.0) and 3-year old males had the lowest with 0.59 (0.35-0.83). We estimated growth rate using population estimates from Jolly-Seber, direct recoveries, and minimum population size methods. The lowest growth rate estimated was for all females (ages lumped) using minimum population size data (λ=0.82). Direct recovery data for all bears (sex and age lumped) during 1995 - 2000 showed the highest positive annual growth rate (λ = 1.24). We developed a population model using Mathcad 8 Professional to determine population growth rate, MVP, and harvest effects for an exploited black bear population in southwestern Virginia. We used data collected during the CABS study (1995 - 2000) in the model including population estimates derived from direct recovery data, age and sex specific survival rates, and cub sex ratios. When we used actual population values in the model, the bear population in southwestern Virginia did not go extinct in 100 years (l = 1.03, r = 0.03). When we reduced adult female survival from 0.94 to 0.89, the probability of extinction in 100 years was 3.0% and l = 0.99 (r = -0.01; Table 3.2). When the survival was reduced by an additional 0.01 to 0.88, the probability of extinction increased to 13.0% (l = 0.99, r = -0.01). Growth rate and extinction probabilities were very sensitive to adult female survival rates. Two-year old and 3-year old females did not impact extinction probabilities and growth rates as much as adult females. Their survival could be decreased by 44.0%, and still be less than the 5.0% extinction probability.<br>Master of Science

Body size varies according to nutritional availability, which is of ecological and evolutionary relevance. The purpose of this study is to test the hypothesis that differences in adult body size are realized by increasing juvenile growth rate for white-tailed deer (Odocoileus virginianus). Harvest records are used to construct growth rate estimates by empirical nonlinear curve fitting. Results are compared to those of previous models that include additional parameters. The rate of growth increases during the study period. Models that estimate multiple parameters may not work with harvest data in which estimates of these parameters are prone to error, which renders estimates from complex models too variable to detect inter-annual changes in growth rate that this simpler model captures

Hypervariable, nuclear-encoded microsatellites were used to (i) estimate genetic effective size (Ne) of red drum spawning over a two-week period in nine brood tanks at a TPWD hatchery; (ii) estimate heritability of early-larval growth and of growth rate and cold tolerance of juveniles; and (iii) test Mendelian segregation and independent assortment of 31 nuclear-encoded microsatellites. Assuming all tanks contributed equally to an offspring population, the maximum (expected) and observed Ne over the nine brood tanks was 43.2 and 27.0, respectively. The estimate of Ne based on observed variation in family size was 19.4. Simulations indicated that over a limited time period the simplest approach to maximizing Ne for a release population would be to utilize equal numbers of progeny from each brood tank. A family (genetic) effect was found to contribute significantly to the variance in early larval growth, juvenile growth rate, and cold tolerance. Estimates of narrow-sense heritability for these three traits were 0.07 +- 0.03, 0.52 +- 0.21 and 0.20 +- 0.10 (two growth intervals measured), and 0.30 +- 0.11, respectively, under the genetic models employed. The relatively low estimate of heritability for early larval growth suggests that genetic improvement for this trait likely would be slow. The heritability estimates for juvenile growth rate and cold tolerance, alternatively, suggest that genetic selection for these traits could be effective. Segregation at all 31 microsatellites fit Mendelian expectations for autosomal loci; a null allele was inferred at two of the microsatellites. Results from pairwise tests of independent assortment demonstrated that 20 of the 31 microsatellites could be placed into seven linkage groups. Additional linkage groups inferred from a prior study increased the number of inferred linkage groups in red drum to nine, with a range of two - five (avg. = 2.78) microsatellites in each linkage group. The remaining 11 microsatellites tested in this study assorted independently from all other microsatellites, suggesting the possibility of 11 additional linkage groups.

The effect of the element length is examined in modelling crack growth in fatigue loading of an adhesive joint. This is done for a cohesive element using an expression for the damage evolution developed at the University of Skövde which is implemented using the UMAT subroutine in the FE-solver Abaqus. These analyses are done for pure mode I loading by analysing a DCB-specimen loaded by a pure moment. An expression is developed in which the critical element length is dependent on the geometry of the specimen (in the form of the wave number of the adhesive joint), the element length, the material properties of the adhesive (in form of the material parameters , , ), the load applied (in form of the stress in the crack tip), the time step used in the analysis and the crack growth rate. It is shown that the results converge by decreasing the element length and the time step used. Therefore an expression for the crack growth rate as a function of the remaining parameters can be determined. Another expression is thereafter developed for the element length needed in order to get a crack growth rate within a certain range of the critical element length. The results show a regular pattern but are not monotone. Therefor two different definitions of the critical element length are tested, either by defining the critical element length as the point where the error is greater than an arbitrary boundary of 1 % of a converged result or where a least square approximation of the error is within 1 % of the converged results. The first method shows a highly irregular result which makes it difficult to develop an expression out of these results. The second method on the other hand gives results that are predictable enough to develop a function out of them. This is done using a regression analysis with all parameters of a third order expression in order to get an expression.

In my thesis I present data collected from a long-term selection experiment using the freshwater model organism Chlamydomonas reinhardtii. The selection experiment was designed to disentangle the effects of the number of multiple environmental drivers (MEDs) and the identity of those environmental drivers including high CO2, high temperature, general nutrient depletion, reduced light intensity, reduced phosphate availability, the addition of a herbicide, UV radiation and reduced pH. Using up to eight environmental drivers, I show how simple organisms such as C. reinhardtii evolve in response to MEDs. The first step in this investigation is to examine the short-term response of MEDs. Data collected at the beginning of the selection experiment will provide insight into the early stages of microevolution by investigating key differences in the short-term (plastic) responses to few vs. many MEDs. Here, I focus on how the data collected from the responses to single environmental drivers can help us predict the responses to MEDs by using ecological models (additive, comparative, multiplicative). I show that the short-term plastic responses to single environmental drivers can predict the effect of MEDs using the comparative model because the response is largely driven by the single dominant driver present. I also demonstrate the importance of the number of environmental drivers (NED) for making predictions from the single environmental drivers and show that predictions become more reliable as the NED increases. The results gathered from short-term responses provide evidence that single environmental driver studies are useful for predicting the effect of MEDs. After evolution, I found that the strength of selection varies with NED in a predictable way, which connects the NED to the evolutionary response (size of the direct response) through the strength of selection. Here, I used statistical models to quantify the effect of NED on the evolutionary response to MEDs and then interpreted this by considering the possible genetic constraints on adaptation to MEDs. A subset of populations evolved in environments with five environmental drivers and all populations evolved in the single environmental driver environments are used to examine how adapting to single vs. many environmental drivers affect local adaptation. I examine how populations selected in environments with one environmental driver, five environmental drivers and the evolved control, differ in their response to new environments with the same NED, environments with different NED, and a novel environment. I found that there is a relationship between local adaptation and the strength of selection in the local environment and patterns of local adaptation are affected by the NED of new environments. Lastly, I present the phenotypic consequences of evolution under MEDs. I found that before evolution, measures of chlorophyll content and cell size decline with increasing NED. However, after evolution the relationship between chlorophyll content and cell size with NED is weaker because populations converge on the same phenotypes as they evolve. I also present a case-study of how mass spectrometry methods can be used to better understand underlying molecular mechanisms of two phenotypes (chlorophyll positive and chlorophyll negative cells). This selection experiment is a good example of how laboratory investigations and model organisms can be used to design experiments with enough replication to have high statistical power in order to make more accurate predictions on the short- long-term effects of MEDs. Whilst there have been some studies on the effects of MEDs, these studies rarely have more than three environmental drivers (sometimes 5 environmental drivers) and there are only a handful of long-term MED studies. This study can be used to develop a priori hypotheses for investigating how environmental change will shape natural microbial communities, and is especially useful for organisms where long-term studies with multiple environmental drivers are unfeasible.

An understanding of compartment fire behaviour is important for fire protection engineers. For design purposes, whether to use a prescriptive code or performance based design, life safety and property protection issues are required to be assessed. The use of design fires in computer modelling is the general method to determine fire safety. However these computer models are generally limited to the input of one design fire, with consideration of the complex interaction between fuel packages and the compartment environment being simplified. Of particular interest is the Heat Release Rate, HRR, as this is the commonly prescribed design parameter for fire modelling. If the HRR is not accurate then it can be subsequently argued that the design scenario may be flawed. Therefore the selection of the most appropriate fire design scenario is critical, and an increased level of understanding of compartment behaviour is an invaluable aid to fire engineering assumptions. This thesis details an experimental study to enhance the understanding of the impact and interaction that the size and location of pool fires within an enclosure have upon the compartment fire behaviour. Thirty four experiments were conducted in a reduced scale compartment (½ height) with dimensions of 3.6m long by 2.4m wide by 1.2m high using five typical ventilation geometries (fully open, soffit, door, window and small window). Heptane pool fires were used, located in permutations of three evenly distributed locations within the compartment (rear, centre and front) as well as larger equivalent area pans located only in the centre. This thesis describes the experimental development, setup and results of the experimental study. To assist in the classification of compartment fire behaviour during the experiments, a ‘phi’ meter was developed to measure the time dependent equivalence ratio. The phi meter was developed and configured to measure O₂, CO₂ and CO. The background development, calibration, and experimental results are reported. A review of compartment fire modelling using Fire Dynamics Simulator, has also been completed and the results discussed. The results of this experimental study were found to have significant implications for Fire Safety Engineering in that the size of the fire is not as significant as the location of the fire. The effect of a fire near the vent opening was found to have a significant impact on compartment fire behaviour with the vent located fuel source increasing the total compartment heat release rate by a factor of 1.7 to that of a centrally placed pool fire of the same total fuel area. The assumption that a fire located in the centre of the room provides for the highest heat release rate is not valid for post-flashover compartment fires. The phi meter was found to provide good agreement with the equivalence ratio calculated from total compartment mass loss rates, and the results of FDS modelling indicate that the use of the model in its current form can not be applied to complex pool fire geometries.

A wide majority of orchid populations are decreasing due to habitat fragmentation and to changes in land management. Population size, density and habitat quality are factors that are expected to be positively related to the viability and future growth of a population. We evaluated if population size, density and soil organic matter were good predictors of growth, survival, flowering, recruitment, and growth rate in 18 populations of the long-lived orchid Gymnadenia conopsea. We followed the populations for four years. Recruitment in 2020 increased with population size, and survival in 2018 was higher in denser populations. However, flowering probability and number of flowers both decreased with population size in 2018. Soil organic matter did not significantly influence any vital rate. In total, the studied population factors could explain very little of the variation in demography. The matrix modelling showed that 14 of the 18 populations had a positive stochastic growth rate, even with an increased probability of summer drought (scenario with 50% of the years equal to the dry summer of 2018). In the populations with negative growth rate, the probability of quasi-extinction in the next 50 years varied from 90 to 100%. Declining populations were characterized by low survival following the dry year. In sum, population size, density and soil organic matter did not convincingly explain variation in growth rate of G. conopsea, suggesting that other environmental factors are responsible of governing variation in vitals rates and population dynamics.

The AARDVARK (Aortic Aneurysmal Regression of Dilation: Value of ACE-Inhibition on RisK) trial was designed to investigate whether ACE-inhibition reduces the growth rate of small abdominal aortic aneurysms (AAA), independent of blood pressure (BP) lowering. A cohort of patients from the AARDVARK trial contributed data to the CAVE sub-study which investigated the roles of peripheral and central BP and 3 measures (standard deviation, coefficient of variation and variation independent of the mean) of visit-to-visit BP variability (BPV) of peripheral and central BPs on the size and growth rate of the diameters of small AAAs. Subjects aged ≥55 years with AAA diameter 3.0–5.4 cm were randomised 1:1:1 to receive perindopril 10 mg, or amlodipine 5 mg, or placebo. Three standardised BP measurements and an AAA ultrasound scan were performed at every trial visit (every 3-6 months over 2 years). Five of 14 trial sites were provided with a BP+ machine which measures both peripheral and central BP. Nine sites collected peripheral BP only with an Omron machine. BPV was based on readings taken after 3 months to avoid confounding from the impact of trial treatments. The primary outcome of the AARDVARK trial was AAA diameter growth (based on external antero-posterior ultrasound measurements in the longitudinal plane), determined by multi-level modelling. 224 patients were randomised between 2011 and 2013 to receive either placebo (n = 79), perindopril (n = 73), or amlodipine (n = 72). Mean baseline age, peripheral BP and AAA size among the 224 patients who contributed peripheral BP data were 71.3 years, 131.5/77.7 mmHg and 4.0cm (external diameter) respectively and were not significantly different from the 139 patients who also contributed central BP data. No significant differences in the modelled annual growth rates were apparent among the 3 randomised groups [placebo 1.68 mm (SE 0.2), perinodopril 1.77 mm (0.2), and amlodipine 1.81 mm (0.2), respectively]. The estimated difference in annual growth between the perindopril and placebo group was 0.08 mm (CI 20.50, 0.65). No evidence of an association was found between peripheral or central BP and AAA size at baseline or AAA growth in-trial. However, significant associations were found between central (but not peripheral) BPV and AAA growth using linear regression after adjustment for possible confounders. This association was stronger for central diastolic than systolic BPV. Evidence of a dose-response effect (albeit underpowered due to this comparison being restricted to quartiles) was apparent, with patients having the most variable central BP exhibiting the highest AAA growth rates. In the AARDVARK trial, small AAA growth rates were lower than anticipated thereby reducing the power of the trial, but there was no apparent impact of perindopril compared with placebo or placebo and amlodipine combined on AAA growth rates, despite more effective BP lowering among those allocated to perindopril. However by contrast, in the CAVE sub-study we showed a significant association between all 3 measures of central BPV and AAA growth despite the small sample size and limited numbers of visits. A larger study is required to confirm these results.

Understanding how temperature affects biological systems is a central question in ecology and evolutionary biology. Anthropogenic climate change adds urgency to this topic, as the demise or success of species under climate change is expected to depend on how temperature affects important aspects of organismal performance, such as growth, development, survival and reproduction. Rates of biological processes generally increase with increasing temperature up to some maximal temperature. Variation in the slope of the initial, rising phase has attracted considerable interest and forms the focus of this thesis. I explore variation in growth rate-temperature relationships over several levels of biological organization, both between and within species, over individuals’ lifetime, depending on the ecological context and in relation to important life history characteristics such as generation length and winter dormancy.       Specifically, I examine how a clade of temperate damselflies have adapted to their thermal environment along a 3,600 km long latitudinal transect spanning from Southern Spain to Northern Sweden. For each of six species, I sampled populations from close to the northern and southern range margin, as well from the center of the latitudinal range. I reared larvae in the laboratory at several temperatures in order to measure indiviudal growth rates. Very few studies of thermal adaptation have employed such an extensive sampling approach, and my finding reveal variation in temperature responses at several levels of organization.       My main finding was that temperature responses became steeper with increasing latitude, both between species but also between latitudinal populations of the same species. Additional genetic studies revealed that this trend was maintained despite strong gene flow. I highlight the need to use more refined characterizations of latitudinal temperature clines in order to explain these findings. I also show that species differ in their ability to acclimate to novel conditions during ontogeny, and propose that this may reflect a cost-benefit trade-off driven by whether seasonal transitions occur rapidly or gradually during ontogeny.       I also carried out a microcosm experiment, where two of the six species were reared either separately or together, to determine the interacting effects of temperature and competition on larval growth rates and population size structure. The results revealed that the effects of competition can be strong enough to completely overcome the rate-depressing effects of low temperatures. I also found that competition had stronger effects on the amount of variation in growth rates than on the average value.       In summary, my thesis offers several novel insights into how temperature affects biological systems, from individuals to populations and across species’ ranges. I also show how it is possible to refine our hypotheses about thermal adaptation by considering the interacting effects of ecology, life history and environmental variation.

Made available in DSpace on 2016-03-15T19:26:44Z (GMT). No. of bitstreams: 1 Patricia Fabian Holzmann.pdf: 616808 bytes, checksum: e166252bee6ff56d9a6645cc9d778c3c (MD5) Previous issue date: 2009-03-03<br>This study has analyzed the service franchising enterprises evaluating factors that influence the survival rate of this population under the Organizational Ecology theory. The dynamics of the evolution process of this population was analyzed considering the density dependence model connected to legitimation and competition. Such factors, as well as size, were tested in statistic models (panel, logit and probit) using the data base developed with the information presented in the Guias da Associação Brasileira de Franquias between 1996 and 2007, to evaluate their impact over the population survival rate. Other relevant factors raised in Evolutionary Economics and Service Market Organization were also discussed.<br>Este estudo analisou as franquias de serviços avaliando os fatores que influenciam na taxa de sobrevivência dessas empresas sob a ótica da Ecologia Organizacional. A dinâmica da evolução da população de franquias de serviços foi avaliada com base na densidade da população e processos de legitimação e competição. Tais fatores, assim como o tamanho, foram testados em modelos estatísticos (modelo econométrico de painel, logit e probit) utilizando base de dados desenvolvida com base nos Guias da Associação Brasileira de Franquias entre o período de 1996 e 2007, para avaliar seu impacto sobre a taxa de sobrevivência da população. Com base nas teorias de Economia Evolucionária e Organização de Mercado em Serviços outros fatores relevantes para a sobrevivência das franquias de serviço também foram discutidos.

The mechanisms that control growth processes in biology tissues have attracted continuous research interest despite their complexity. With the emergence of big data experimental approaches there is an urgent need to develop statistical and computational models to fit the experimental data and that can be used to make predictions to guide future research. In this work we apply statistical methods on growth process of different biological tissues, focusing on development of neuron dendrites and tumor cells. We first examine the neuron cell growth process, which has implications in neural tissue regenerations, by using a computational model with uniform branching probability and a maximum overall length constraint. One crucial outcome is that we can relate the parameter fits from our model to real data from our experimental collaborators, in order to examine the usefulness of our model under different biological conditions. Our methods can now directly compare branching probabilities of different experimental conditions and provide confidence intervals for these population-level measures. In addition, we have obtained analytical results that show that the underlying probability distribution for this process follows a geometrical progression increase at nearby distances and an approximately geometrical series decrease for far away regions, which can be used to estimate the spatial location of the maximum of the probability distribution. This result is important, since we would expect maximum number of dendrites in this region; this estimate is related to the probability of success for finding a neural target at that distance during a blind search. We then examined tumor growth processes which have similar evolutional evolution in the sense that they have an initial rapid growth that eventually becomes limited by the resource constraint. For the tumor cells evolution, we found an exponential growth model best describes the experimental data, based on the accuracy and robustness of models. Furthermore, we incorporated this growth rate model into logistic regression models that predict the growth rate of each patient with biomarkers; this formulation can be very useful for clinical trials. Overall, this study aimed to assess the molecular and clinic pathological determinants of breast cancer (BC) growth rate in vivo.

碩士<br>國立臺灣大學<br>化學工程學研究所<br>100<br>In this work, the optimization of seeded batch crystallization processes is investigated when crystal growth rate is size-dependent. The process model with size-dependent growth was solved using the Quadrature Method of Moment (QMOM), Method of Characteristics (MOCH) and Duhamel’s Principle as proposed by Qamar et al. [Chem. Eng. Sci., 2009; 64: 3659-3667]. Four systems were studied: a dimensionless model based on previous work by Ward et al. [AIChE J., 2011; 54 (3) 606-617], and three case studies based on real crystallization kinetics reported in the literature. Investigation of the dimensionless model using the objective of minimizing the nucleus-grown crystal mass shows that the size-dependency of the growth rate has only a small effect on the shape of the optimal supersaturation trajectory, i.e. an approximate, size-independent model can be used for the optimization with little error. This is advantageous because optimizing the size-independent model requires much less computational effort. Results from the real case studies also support this conclusion. A modification to the procedure of Qamar is also proposed: By calculating a parameter exactly instead of using an approximation recommended by Qamar, the accuracy of the approximation can be significantly improved without a significant increase in computational effort. The error is reduced from more than 60% to less than 1% in the case where the nucleated crystal mass is large. Finally, it is also shown that optimization over the supersaturation trajectory is preferable to optimization over the temperature trajectory.

There is a growing recognition that conservation programs using hatchery-reared fish should strive to produce individuals that represent phenotypes present in natural environments. Size variability within cohorts, mediated through inter-individual differences in growth rates, provides one avenue by which phenotype can be studied. High growth rates are generally equated with greater fitness. However, there is evidence that fish with slower relative growth and smaller sizes continue to persist within populations. This thesis aimed to better understand the causes and potential implications of variable sizes and growth rates on the potential recruitment of hatchery-reared Lake Sturgeon, Acipenser fulvescens. Studies were developed to 1) determine the mechanisms behind these observed variations and 2) assess the behavioural and physiological consequences of being either a fast- or slow-grower (i.e., large or small). Laboratory studies concluded that external factors, most notably the presence of conspecifics during feeding events, influenced size variability more than inherent predispositions towards faster or slower growth. Examination of size-dependent versus size-independent feeding interactions further confirmed that variability does not appear to be the result of underlying fixed behaviours. The consequence of slower growth rates and smaller sizes did not lead to higher mortality or reduced body condition during a low temperature challenge. Recapture rates and downstream movements following stocking events of both young-of-the-year (YOY) and yearling Lake Sturgeon in the Winnipeg River, Manitoba could not be correlated to inter-individual differences in size. Although initial study on the cause of growth and size divergence may lead one to conclude that slow-growing (i.e., small) Lake Sturgeon represent a substandard phenotype, subsequent studies could not point to inferior performance of these individuals when compared to faster-growing (i.e., large) individuals of the same age. As such, the practice of size-selection for relatively faster-growing and larger individuals in future Lake Sturgeon enhancement programs is discouraged, at least until there are more conclusive findings to suggest otherwise. Future studies should continue to look at recruitment in relation to growth rate and size among naturally produced Lake Sturgeon juveniles in order to put the results of this research into context.

碩士<br>國立臺灣大學<br>生態學與演化生物學研究所<br>101<br>Allometric scaling of body size versus growth rate and mortality has been suggested to be a universal macroecological pattern, as described by the metabolic theory of ecology (MTE). However, whether such scaling generally holds in natural assemblages remains debated. Here, we test the hypothesis that the size-specific growth rate and grazing mortality scale with the body size with an exponent of -1/4 after temperature correction, as MTE predicts. To do so, we couple a dilution experiment with the FlowCAM imaging system to obtain size-specific growth rates and grazing mortality of natural microphytoplankton assemblages in the East China Sea. This novel approach allows us to achieve highly resolved size-specific measurements that would be very difficult to obtain in traditional size-fractionated measurements using filters. Our results do not support the MTE prediction. On average, the size-specific growth rates and grazing mortality scale almost isometrically with body size (with scaling exponent ~0.1). However, this finding contains high uncertainty, as the size-scaling exponent varies substantially among assemblages. The fact that size-scaling exponent varies among assemblages prompts us to further investigate how the variation of size-specific growth rate and grazing mortality can interact to determine the microphytoplankton size structure, described by normalized biomass size spectrum (NBSS), among assemblages. We test whether the variation of microphytoplankton NBSS slopes is determined by 1) differential grazing mortality of small versus large individuals, 2) differential growth rate of small versus large individuals, or 3) combinations of these scenarios. Our results indicate that the ratio of the grazing mortality of the large size category to that of the small size category best explains the variation of NBSS slopes across environments, suggesting that higher grazing mortality of large microphytoplankton may release the small phytoplankton from grazing, which in turn leads to a steeper NBSS slope. This study contributes to understanding the relative importance of bottom-up versus top-down control in shaping microphytoplankton size structure.

Available evidence suggests that interannual variability in the recruitment of Pacific salmon is related to survival in the first few months juveniles spend at sea. Differential growth of smolts during this stage is often thought to result in interannual differences in marine survival, as those fish that grow faster may be less vulnerable to predators or physiological and environmental stressors associated with overwintering (i.e. the 'differential growth' hypothesis). Due to the limitations of traditional techniques, however, only rarely has salmon growth been reliably characterized during the early marine stage. Using juvenile chum salmon (Oncorhynchus keta) collected in the Nanaimo area (1999-2001), I demonstrate that otoliths provide a powerful means of examining the early life history of individual salmon in the field. I used a fluorescent marker to validate the daily periodicity of otolith increment formation, and the formation of a marine entry check. I then back-calculated size-atmarine- entry for each chum smolt to provide individual estimates of early marine growth rate from the summers of 1999 and 2000. Mean daily growth rates were significantly higher, and size-at-entry significantly larger, in 1999 (0.084 cm day"1, 4.48 cm) than in 2000 (0.076 cm day"1, 3.97 cm). 1999 was also a year of significantly higher gut fullness and lower sea surface temperatures. By comparing growth rate frequencies across trips, I found evidence for size-selective mortality of slow growing fish in the midsummer of 2000. These patterns are consistent with the "differential growth hypothesis". In years of unfavourable ocean conditions, juvenile salmon may experience slower growth and higher rates of size-selective predation (possibly due to low food availability or quality). This, in turn, may lead to below average survival and recruitment in these years.

Tese de doutoramento em Biologia apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra<br>A formação de aneís de crescimento é um processo lento e complexo. A variabilidade climática interanual e a interacção entre os factores internos e externos que regulam a actividade cambial são os grandes responsáveis pela singularidade de cada anel de crescimento. De maneira a capturar a dinâmica da actividade cambial e da formação de madeira ao longo do período de crescimento, é necessária a sua monitorização ao longo do ano e a uma escala temporal reduzida (de minutos a semanas). A grande maioria dos estudos sobre actividade cambial e formação de madeira foi realizada em ambientes limitados pela temperatura. Noutros ambientes, e em especial naqueles limitados por condições de seca, continua a ser um assunto pouco estudado. Com o intuito de melhor caracterizar a actividade cambial e a formação de madeira na região Mediterrânica, a actividade cambial do pinheiro bravo (Pinus pinaster Ait.) foi monitorizada ao longo de dois anos (2010 e 2011). Para tal, foram feitas observações anatómicas da zona cambial e xilema em desenvolvimento, e monitorizado o incremento radial do tronco através de dendrómetos manuais e automáticos. Os estudos descritos nesta tese foram realizados no Perímetros Florestal Dunas de Cantanhede, uma plantação gerida de pinheiro-bravo, localizada na costa Oeste Portuguesa. A actividade cambial e a formação de madeira em pinheiros-bravos de idade e tamanho semelhantes, mas taxas de crescimento distintas entre 1994 e 2009 (árvores de crescimento rápido e lento), foi seguida ao longo do ano de 2010, com o objectivo de determinar se as diferenças observadas no tamanho dos anéis de crescimento foram devidas a diferenças no período de actividade cambial ou na taxa de divisão celular. O início da actividade cambial ocorreu simultâneamente em ambas as classes de crescimento. Contudo, as árvores de crescimento rápido apresentaram taxas de divisão celular maiores. As variações do diâmetro do tronco revelaram um padrão de crescimento bimodal, composto por dois picos de incremento, um de maior intensidade na Primavera e outro no Outono. Apesar de o padrão de crescimento bimodal ser característico da região Mediterrânica, a análise conjunta das observações anatómicas e das curvas de incremento do tronco revelaram que o segundo período de incremento correspondeu maioritariamente à re-hidratação do tronco, e não à reactivação da actividade cambial. Com o objectivo de determinar se diferenças no diâmetro do tronco foram devidas a diferentes taxas de divisão celular ou a diferenças no perído de xilogénese, a actividade cambial de árvores com idade idêntica, mas com troncos de diâmetro diferente, foi seguida ao longo de 2011. O início da actividade cambial e diferenciação de xilema ocorreu simultaneamente em ambas as classes de diâmetro. Contudo, as fases de expansão e de deposição da parede secundária apresentaram uma maior duração nas árvores de maior diâmetro. Foi ainda observado que as árvores de maior diâmetro apresentaram uma maior taxa de divisão celular. Assim, foi concluído que as diferenças de diâmetro do tronco observadas em árvores da mesma idade foram devidas diferentes taxas de divisão celular. Em ambas as classes de diâmetro o câmbio permaneceu activo de Março a Julho, e quiescente de Agosto a Novembro. O período de actividade cambial descrito no pinheiro-bravo sugere um duplo controlo climático na região Mediterrânica: temperaturas baixas e fotoperíodo curto no Inverno, e temperaturas elevadas e baixa disponibilidade hídrica no Verão. A quiescência de Verão terminou após as primeiras chuvas após a seca de Verão (Outubro), que causaram a re-hidratação do tronco. Foram ainda observadas divisões celulares no câmbio em Novembro, o que é indicativo da capacidade do pinheiro bravo em produzir novas células de xilema após a seca de Verão. A influência do clima, e em especial da disponibilidade hídrica, na actividade cambial do pinheiro bravo foi estudada ao longo de 2 anos (2010 e 2011). Foi determinado que um início precoce da actividade cambial estava relacionado com temperaturas mais amenas no final do Inverno. Observou-se ainda que o final precoce da actividade cambial estava relacionado com um Verão quente e com menor disponibilidade hídrica, confirmando um duplo controlo climático no crescimento das árvores. A baixa disponibilidade hídrica registada na Primavera e no Verão afectou negativamente o tamanho do anel de crescimento, promovendo o início precoce da formação do lenho tardio. Os traqueídos do lenho tardio, além de em menor número, apresentaram também uma menor área do lúmen. Observou-se ainda que o início e a duração da actividade cambial são independentes, uma vez que um início precoce não se traduziu num maior período de actividade cambial. Finalmente, para determinar o efeito da disponibilidade hídrica nos ciclos diários e sazonais de incremento radial do tronco de pinheiro-bravo, a variação horária do incremento radial e o défice de água no tronco foram monitorizados ao longo de 2010. O incremento radial do tronco foi dividido em cinco períodos distintos de actividade fisiológica da árvore: dormência de Inverno, crescimento primaveril, contracção antes do Verão, quiescência de Verão e re- hidratação de Outono. Estes períodos foram estudados individualmente com o intuito de perceber as variações na amplitude e na duração das várias fases do ciclo diário de incremento radial do tronco ao longo do ano. O ciclo diário foi dividido nas fases de contracção, recuperação e incremento. Um período contínuo de incremento radial positivo foi observado durante a Primavera, atingindo o máximo em Junho. Este máximo foi seguido de um período de contracção, devido à incapacidade das árvores em recuperar a água perdida por transpiração durante o dia. O tronco das árvores foi contraindo até a árvore entrar em quiescência. A re-hidratação e expansão do tronco foi observada após as primeiras chuvas, no Outono. As variações diárias do diâmetro do tronco de pinheiro bravo foram fundamentalmente devidas à transpiração e por isso dependentes da temperatura e da disponibilidade hídrica. Os resultados da presente tese forneceram informação detalhada sobre a dinâmica cambial de pinheiro-bravo proveniente de uma zona caracterizada por um período de seca sazonal, a região Mediterrânica. Foi observado que a taxa de divisão celular foi a principal responsável pelas diferenças encontradas no tamanho dos anéis anuais de crescimento, culminando em diferenças significativas no diâmetro do tronco de árvores de idade semelhante. Numa floresta gerida com árvores de idade semelhante, é possível encontrar indivíduos com taxas de divisão celular diferentes (crescimento rápido e lento), e que com o passar do tempo se irão acumular e expressar como diferenças de diâmetro (árvores de maior e menor diâmetro). Foi concluído que o início da actividade cambial foi independente do tamanho da árvore, contudo uma maior duração da formação de madeira foi observada nas árvores de maior diâmetro e com taxas de crescimento rápidas. O incremento radial de todas as árvores estudadas em 2010 e 2011 apresentou um padrão bimodal típico da região Mediterrânica, com dois picos de incremento. O primeiro pico foi mais pronunciado e ocorreu na Primavera, enquanto que o segundo pico, menos pronunciado, foi observado no Outono. O segundo pico de incremento radial correspondeu à re-hidratação do tronco após a seca de Verão. O clima desempenhou também um papel importante na formação de madeira, com as temperaturas baixas e fotoperíodo curto durante o Inverno, e as temperaturas elevadas e baixa disponibilidade hídrica no Verão, a imporem períodos de dormência cambial.<br>The formation of tree rings is a slow and complex process. The year-to-year climatic variability and the constant interaction between the internal and external factors controlling cambial activity, create the conditions that make each tree ring unique. In order to capture the dynamics of cambial activity and wood formation during the growing season, it is necessary to monitor wood development in narrower time intervals (from minutes to weeks). Most of the studies on cambial activity and wood formation were held in cold environments, but in other environments, such as drought-prone areas, still remains poorly understood. In order to understand the cambial activity and wood formation under Mediterranean climate, a droughtprone environment, timing and dynamics of cambial activity in maritime pine (Pinus pinaster Ait.) were monitored during two years (2010 and 2011). Anatomical observations of the cambial zone and differentiating xylem were made and stem radial increment monitored using manual and automatic dendrometers. The studies described in this thesis were carried out in Perimetro Florestal Dunas de Cantanhede, a managed plantation of maritime pine located in the west coast of Portugal. The cambial activity and wood formation of maritime pine trees with the same age and size but different growth rates in the period 2009-1994 (classified as fast and slow trees), was monitored throughout 2010, to determine whether the observed differences in tree-ring width were triggered by the timing of cambial activity or by the rate of cell production. It was determined that the timing of cambial activity was similar in both growth rate classes. However, fast-growing trees presented higher rates of rate of cell production than slowgrowing trees. The band dendrometer readings revealed a bimodal pattern of stem radial increment, with two peaks of increment, one more pronounced in spring and another in autumn. Although the bimodal pattern is typical of trees growing in the Mediterranean region, the combined analysis of anatomical observations of the cambial region and band dendrometers showed that the second period of radial increment corresponded mostly to the re-hydration of the stem, since no resumption of cambial activity was observed in autumn. In order to determine if differences in stem diameter were due to different rates of cell production or xylogenesis timings, the cambial activity of even-aged trees belonging to two diameter classes was monitored throughout 2011. The timings of cambial onset and differentiation were the same in both diameter classes. However, enlargement and cell wall deposition lasted longer in large trees. Besides the different durations, large trees also showed a higher rate of cell production. Thus, revealing that the differences in diameter observed between the trees were due to the rates of cell production. In both diameter classes, the cambium was active from March to July, and quiescent from August to November, suggesting that in the Mediterranean region, trees are under a double climatic control: low temperatures and reduced photoperiod in the winter and high temperatures associated with low water availability in the summer. Summer quiescence was broken in late October, when precipitation re-hydrated the stem. In November, cambial divisions were observed, indicating that maritime pine has the ability to form new xylem cells after the summer drought. The influence of climate on the cambial activity and wood formation of maritime pine was studied over two dry years (2010 and 2011). It was found that cambial onset started earlier in response to a warmer late-winter and stopped earlier in response to a drier spring and summer, confirming that Mediterranean conifers are under a double climatic control. Low water availability during spring and summer limited cell production, which affected tree-ring width. Drier conditions also triggered an earlier start of latewood formation, leading to the development of fewer tracheids with smaller lumen area. It was also observed that the duration of xylogenesis was not dependent on cambial onset. In fact, an earlier onset of xylogenesis did not trigger a longer duration of cambial activity. To ascertain the influence of water availability on stem radial increment of maritime pine, hourly variations of stem radial increment and tree water deficit were monitored throughout 2010 using automatic dendrometers. The seasonal cycle was divided in five periods of distinct physiological activity: winter dormancy, spring growth, pre-summer contraction, summer quiescence and autumn re-hydration. The stem cycle approach was then used to divide the daily cycles in contraction, recovery and increment phases. Continuous positive radial increment started in spring and reached its maximum by the end of June, time at which a shrinking period was observed. The stem contraction observed in June was due to the inability of trees to recover the water lost by transpiration, contracting from one cycle to the next. In autumn, a period of re-hydration and rapid expansion was observed after precipitation. Daily variations in stem radius of maritime pine were mainly determined by the course of transpiration and thus, highly dependent on temperature and water availability. Overall, the results obtained in this dissertation provided a detailed insight on the dynamics of maritime pine cambial activity in a drought-prone environment, the Mediterranean region. It was observed that the cell production rate was the main responsible for the differences in tree-ring width and ultimately in stem diameter. Within an even-aged and managed forest, different individuals can present different cellular production rates (fast and slow trees) that in time will be translated in different stem diameters (larger and smaller trees). Growth onset was not influenced by the size of the tree, but a longer duration of wood formation was observed in fast-growing and larger trees. In both years (2010 and 2011), the radial increment of all studied trees presented a clear bimodal pattern, with two increment peaks, as observed in other Mediterranean species. The first and more pronounced peak occurred in spring and a second less pronounced peak in autumn. The second growth peak corresponded mainly to a re-hydration of the stem after the summer drought. Climate played an important role in maritime pine cambial activity and wood formation, low temperatures and reduced photoperiod in winter and high temperatures associated with low water availability in the summer limited tree growth by imposing a dormant period.<br>POPH (Portuguese Operational Human Potential Programa); QREN Portugal (Portuguese National Strategic Reference Framework) SFRH/BD/48089/2008

The formation of tree rings is a slow and complex process. The year-to-year climatic variability and the constant interaction between the internal and external factors controlling cambial activity create the conditions that make each tree ring unique. In order to capture the dynamics of cambial activity and wood formation during the growing season, it is necessary to monitor wood development in narrower time intervals (from minutes to weeks). Most of the studies performed on cambial activity and wood formation were held in cold environments, however, in other environments, such as drought-prone areas, it still remains poorly understood. In order to understand cambial activity and wood formation in a drought-prone environment, timings and dynamics of cambial activity were monitored in maritime pine (Pinus pinaster Ait.) growing in the Mediterranean region for two years (2010 and 2011). Anatomical observations of the cambial zone and differentiating xylem were made and stem radial increment monitored using manual and automatic dendrometers. The studies described in this thesis were carried out in Perimetro Florestal Dunas de Cantanhede, a managed plantation of maritime pine located in the west coast of Portugal. The cambial activity and wood formation of maritime pine trees with the same age and size but different growth rates in the period 2009-1994 (classified as fast and slow trees), were monitored throughout 2010, to determine whether the observed differences in tree-ring width were triggered by timings of cambial activity or by rates of cell production. Anatomical observations of the cambium and developing xylem determined that the timing of cambial activity was similar in both growth rate classes. However, fast-growing trees presented higher rates of cell production than slow-growing trees. The band dendrometer readings revealed a bimodal pattern of stem radial increment, with two peaks of increment, one more pronounced in spring and another in autumn. Although the bimodal pattern is typical of trees growing in the Mediterranean region, the combined analysis of anatomical observations and band dendrometers showed that the second period of radial increment corresponded mostly to the re-hydration of the stem, since no resumption of cambial activity was observed in autumn. In order to determine if differences in stem diameter were due to different rates of cell production or xylogenesis timings, the cambial activity of even-aged trees belonging to two diameter classes was monitored throughout 2011. The timings of cambial onset and differentiation were the same in both diameter classes. However, enlargement and cell wall deposition lasted longer in large trees. Besides the different durations, large trees also showed a higher rate of cell production. Thus, revealing that the differences in diameter observed between the trees were due to the rates of cell production. In both diameter classes, the cambium was active from March to July, and quiescent from August to November, suggesting that in the Mediterranean region trees are under a double climatic control: low temperatures and reduced photoperiod in the winter and high temperatures associated with low water availability in the summer. Summer quiescence was broken in late October, when precipitation re-hydrated the stem. In November, cambial divisions were observed, indicating that maritime pine has the ability to form new xylem cells after the summer drought. The influence of climate on the cambial activity and wood formation of maritime pine was studied over two dry years (2010 and 2011). It was found that cambial onset started earlier in response to a warmer late-winter and stopped earlier in response to a drier spring and summer, confirming that Mediterranean conifers are under a double climatic control. Low water availability during spring and summer limited cell production, which affected tree-ring width. Drier conditions also triggered an earlier start of latewood formation, leading to the development of fewer tracheids with smaller lumen area. It was also observed that the duration of xylogenesis was not dependent on cambial onset. In fact, an earlier onset of xylogenesis did not trigger a longer duration of cambial activity. To ascertain the influence of water availability on the stem radial increment of maritime pine, hourly variations of stem radial increment and tree water deficit were monitored throughout 2010 using automatic dendrometers. The seasonal cycle was divided in five periods of distinct physiological activity: winter dormancy, spring growth, pre-summer contraction, summer quiescence and autumn re-hydration. The stem cycle approach was then used to divide the daily cycles in contraction, recovery and increment phases. Continuous positive radial increment started in spring and reached its maximum by the end of June, time at which a shrinking period was observed. The stem contraction observed in June was due to the inability of trees to recover the water lost by transpiration, contracting from one cycle to the next. In autumn, a period of re-hydration and rapid expansion was observed after precipitation. Daily variations in stem radius of maritime pine were mainly determined by the course of transpiration and thus, highly dependent on temperature and water availability. Overall, the results obtained in this dissertation provided a detailed insight on the dynamics of maritime pine cambial activity in a drought-prone environment, the Mediterranean region. It was observed that cell production rate was the main responsible for the differences in tree-ring width and ultimately in stem diameter. Within an even-aged and managed forest, different individuals can present different cellular production rates (fast and slow trees) that in time will be translated in different stem diameters (larger and smaller trees). Growth onset was not influenced by tree size, but a longer duration of wood formation was observed in fast-growing and larger trees. In both years (2010 and 2011), the radial increment of all studied trees presented a clear bimodal pattern, with two increment peaks, as observed in other Mediterranean species. The first and more pronounced peak occurred in spring and a second less pronounced peak in autumn. The second growth peak corresponded mainly to a re-hydration of the stem after the summer drought, since the anatomy study did not reveal the formation or differentiation of new xylem cells. Climate played an important role in maritime pine cambial activity and wood formation, low temperatures and reduced photoperiod in winter and high temperatures associated with low water availability in the summer limited tree growth by imposing a dormant period.

Over the past few decades, many countries have experienced a marked decline in the volatility of output. However, there is still a significant difference between developed and developing countries in the level of output volatility. A proposed explanation for this phenomenon is the impact of economic policies on output volatility in developing countries. The empirical results reported in this study support this view. Trade openness and discretionary fiscal policy seem to increase volatility in developing countries, while the converse is true in developed countries. Furthermore, a flexible exchange rate regime is desirable to decrease volatility. However, many developing countries still use fixed rates for reasons such as a fear of floating, which contributes to volatility. The impact of monetary policy was found to be stabilising, but this could be the result of a favourable global economic environment. It should be noted, however, that uncontrollable factors such as financial systems and institutions play a vital role in all the above relationships.<br>Economics<br>M.Com. (Economics)