Dissertations / Theses on the topic 'Zoning and distribution of population'

Growing population, lack of water resources, the massive amount of water withdrawal, and migration of people from rural to urban areas are creating a water scarcity issues in Pakistan. However, the suitable quantity of water resources is decreasing due to the unsustainable extraction. Whereas, the land availability for the construction of domestic areas is reducing gradually because of an urbanization as a result urban areas are becoming overcrowded. Therefore, the aim of present work is to analyse the population distribution in the different provinces of Pakistan as well as the amount of total blue water, people access to drinking water and water withdrawal activities. To determine the outcomes/results the data sets have been downloaded from various sources i.e. SEDAC (NASA), World pop, Joint Research Centre (JRC-GHS), Gridded Population of the World version 4 (GPWv4) and World Resource Institute (WRI). Population distribution and water resources maps have been investigated by the implementation of mapping algebraic approach in the context of Quantum Geographic Information system (QGIS). Classification, overlapping, clipping, masking and other GIS techniques are applied with the help of raster and vectors datasets. Although, by means of zonal statistics tool, we examined the number of people living in each province of Pakistan. However, during the overlapping of population density and water resources maps, we derived the outcomes that in which part of the country people are extracting the massive amount of water resources and where people are facing the water scarcity related issues.

The interconnection of components of industrial automation and control systems (IACS) and enterprise systems involved in processes ranging from generation and transmission to billing within electric utilities poses challenges regarding cyber security as well as division of organisational responsibility. One means of organising these components and systems is to use a zone model in which they are segmented, offering layered defences as well as a logical grouping. One such zone model is the zone model under review, which was presented by Zerbst et al. in a CIRED paper from 2009. This master thesis reviews that zone model and compares it to other industry standard zone models which have been found to be able to be categorised into either functional based models or layered defence models. The outcome is a rough definition of what kind of content fits in the various zones of the reviewed model, as well as a normalised zone model to be used for comparison. A suggested method for dividing system components into zones is based on the 4R-method considering the response time, resolution, reliability and reparability of the system component, although its accuracy has not been empirically tested.

The current housing crisis in Sweden affects more municipalities today than ever before. There is a high demand for all type of tenures and the housing shortage is primarily evident in the metropolitan cities. Sweden has during the last 15 year focused on building for high-income households, with the vision to create migratory chains providing other society groups with housing as well. The migratory chains unfortunately often become significantly short and the housing shortage remains for low-income households. Municipalities are now facing an unsustainable situation, with an urgent need to resolve the situation for low-income households. This needs to be performed without the stigmatization and segregation that clusters of only affordable housing brings. A Swedish pilot project, RiverCity, including affordable housing through inclusionary zoning is currently under development in Frihamnen, Gothenburg. The first phase of the RiverCity that will be completed is called "RiverCity 2021" and includes parts of Frihamnen and Ringön. The completion will coincide with Gothenburg's 400th anniversary in 2021.There are ongoing discussion, and some factors regarding rent setting and distribution of the affordable housing units are not yet determined. It is a new, interesting and innovative development project that has not yet been studied, and therefore considered suitable for a Master of Science thesis project. The thesis and case study was conducted through a qualitative inductive research approach, with a case study of the pilot project in Frihamnen, Gothenburg. The study indicates a high level of innovation among the actors to fulfill the requirements for the assignment of a land allocation. The impression is that the aktors are keen to determine criteria that ensure that the apartments are distributed to households without the financial ability to afford a lease in a new construction building. Inclusionary zoning and requirements in land allocation to develop affordable housing seems to be a prerequisite for the current development of affordable housing. The study provides a basis for further research on the outcomes of the current plans in the future.
Den nuvarande bostadsbristen i Sverige drabbar fler kommuner idag än någonsin tidigare. Efterfrågan på alla boendeformer är hög och bristen på bostäder är framförallt tydlig i storstäderna. De senaste 15 åren har Sverige fokuserat på att bygga för hushåll med relativt hög inkomst, med avsikten att skapa flyttkedjor som i sin tur förser övriga grupper i samhället med bostäder. Flyttkedjorna blir tyvärr ofta korta och bostadsbristen kvarstår för hushåll med lägre inkomster. Kommunerna befinner sig idag i en ohållbar situation; hushåll med lägre inkomster måste akut förses med bostäder, samtidigt som den segregation och sociala stigmatisering som kluster av billiga bostäder för med sig bör undvikas. Ett svenskt pilotprojekt, Älvstaden, som inkluderar affordable housing-lägenheter bland lägenheter med marknadshyror är just nu under utveckling i Frihamnen, Göteborg. Byggstart av den första etappen, Älvstaden 2021, är planerad till 2017 med färdigställande till Göteborgs 400 års jubileum år 2021. En del faktorer angående hyressättning och fördelning av affordable housing-lägenheterna är inte fastställda och diskussion pågår fortfarande. Projektet är innovativt och väldigt intressant för bostadssituationen i Sverige, samt har inte analyserats ännu, vilket tillsammans motiverar en kvalitativ fallstudie av projektet som ämne för denna master uppsats. Studien indikerar på hög innovation ibland de utvalda aktörerna för att uppfylla de krav som ställts i markanvisningarna. Intrycket är att aktörerna är måna om att utforma kriterier som gör att lägenheterna fördelas till hushåll utan ekonomiska förutsättningar för att klara en nyproduktionshyra som inte är subventionerad. Inclusionary zoning och krav i markanvisning om att utveckla affordable housing verkar vara en förutsättning för utveckling av affordable housing. Studien utgör en grund för vidare forskning kring utfallet av de nuvarande planerna i framtiden.

Thesis (MBA)--Stellenbosch University, 2001.
ENGLISH ABSTRACT: The primary objective of this study was to verify the extent to which income distribution among the population groups in South Africa has changed since the 199! population census. These were the findings: It was established in this study that, at October 1996 the income share of Whites had dropped from 71.2 percent (1970) to 51.9 percent. The White population constitute 12.6 percent of South Africa population in 1996 but they received more than 50 percent of personal income in the country. At October 1996 the per capita income of Whites was 8.8 times that of Africans, 4.5 times that of Coloureds and 2.3 times that of Indians. The study found that income disparities between the population groups have narrowed, but there are a lot left to be done to remove income inequalities in the country. The study found that the income which accrued to each population group was not uniformly distributed within the group. In all population groups, the poorest 40%, and the next 41-70% household income classes suffered losses in household income shares between 1991 and 1996. In all population groups it was the richest 10% households who received the lion's share of income which accrued to the group, between 1991 and 1996. The study further found a shift in African employees from elementary occupations to artisan and machine operators. Between 1995 and 1999 the proportion of Coloureds in elementary jobs declined in favour of artisans, machine operators, managers and professionals. Indians and Whites had the smallest proportion of their workforce engaged in elementary occupations Only 5.4 percent of Africans aged 20 and above were found to possess degrees, diplomas and certificates in 1999, compared to 6.5 percent Coloureds, 14.3 percent Indians, 31.5 percent Whites. As high as 15.5 percent of Africans had not received any formal education at October 1999 compared to 7.9 percent Coloureds, 3.5 percent Indians and 0.3 percent Whites. Unemployment in all population groups has increased since the 1996 South African population census.
AFRIKAANSE OPSOMMING: Die primêre doelwit van hierdie studie was om die verandering in die omvang van die inkomsteverdeling tussen die bevolkingsgroepe sedert die 1991 bevolkingsopname te bevestig. Daar is bevind dat die inkomste aandeel van Blankes vanaf 71.2 persent in 1970 na 51.9 persent in 1996 afgeneem het. Die Blanke bevolking het 12.6 persent van die Suid-Afrikaanse bevolking in 1996 uitgemaak, maar hulle ontvang meer as 50 persent van persoonlike inkomste in die land. In Oktober 1996 was die per capita inkomste van Blankes 8.8 keer meer as dié van Swart Suid-Afrikaners en 6.8 keer meer as dié van Kleurlinge. Die studie het gevind dat inkomsteverskille tussen die bevolkingsgroepe verminder het, maar dat daar nog groot inkomste ongelykhede is. Die studie het verder bevind dat die verdeling van inkomste binne elke bevolkingsgroep ongelyk verdeel is. Tussen 1991 en 1996 het in alle bevolkingsgroepe, die armste 40%, en die volgende 41-70% huishoudelike inkomsteklasse 'n daling in hul aandeel van huishoudelike inkomste ondervind. In alle bevolkingsgroepe was dit die rykste 10% huishoudings wat die grootste aandeel aan inkomste ontvang het tussen 1991 en 1996. Die studie het ook gevind dat daar 'n verskuiwing van swart Suid-Afrikaanse werknemers van elementêre beroepe na ambagsmanne en masjienoperateurs plaasgevind het. Tussen 1995 en 1999 het die verhouding van anderskleuriges in elementêre beroepe afgeneem ten gunste van ambagsmanne, masjienoperateurs, bestuurders en professionele beroepe. Asiate en Blankes het die kleinste verhouding van hulle werksmag in elementêre beroepe gehad. In 1999 was slegs 5.4 persent van swart Suid-Afrikaners, ouderdom 20 en ouer, in besit van grade, diplomas en sertifikate, in vergelyking met 6.5 persent Kleurlinge, 14.3 persent Asiate en 31.5 persent Blankes. Tot en met Oktober 1999 het 15.5 persent van swart Suid-Afrikaners geen formele opleiding ontvang in vergelyking met 7.9% Kleurlinge, 3.5% Asiate en 0.3% Blankes. Werkloosheid het sedert 1996 in alle bevolkingsgroepe toegeneem sedert die 1996 Suid-Afrikaanse bevolkingsopname.

Zoning, as a public land-use tool, has several important goals. As zoning accomplishes these goals, however, zoning has had the unintended outcome of guiding high numbers of minorities into certain areas in which multi-family housing is permitted. This study attempts to understand the connection that zoning has with racial and ethnic distribution within and across jurisdictions in the Washington, D.C. MSA.

By using GIS to spatially connect zoning districts to Census data, I analyzed correlations between minority populations and zoning district regulations. For all locations studied, I found that proportions of minority population generally increase as zoning districts permit higher-intensity residential uses. Minority populations often increased as the density permitted by zoning districts increased, although there were many exceptions to this trend, most notably in the central city where minority populations did not directly correlate with zoning density. In all cases, however, low-density, single-family zoning districts had higher white populations than other, higher-density zoning districts. Zoning was shown to have the greatest correlation with minority populations in jurisdictions undergoing significant population growth, particularly minority population growth.

The study shows that racially-segregated neighborhoods exist across a variety of zoning types, including low-density, single-family districts, but that segregation is more abundant within zoning districts that permit higher-intensity uses and higher-densities. White isolation was found to be greatest in low-density, single-family zoning districts.

Although there is a clear connection between zoning regulations and minority population settlement, zoning density does not perfectly correlate with minority population and racially-segregated areas. Many higher-density zoning districts throughout the study area have high white populations and high levels of white clustering. Conversely, high minority populations and minority clustering occur to significant extents in parts of single-family zoning districts, particularly in Washington and Prince George's County.
Master of Urban and Regional Planning

Gli eventi sismici sono riconosciuti come una delle maggiori cause per l’innesco di frane (Keefer, 1984). Le frane sismo-indotte sono documentate sin dal IV secolo (Seed, 1968). È stata condotta un’analisi sulla distribuzione spaziale delle frane sismo-indotte nell’area circostante la sorgente sismogenetica per meglio comprendere il loro innesco in aree sismiche e per delimitare la massima distanza alla quale un sisma con data magnitudo possa indurre frane. Tuttavia, quando si applicano tali approcci a eventi storici si pone un problema legato al sottocampionamento delle frane più piccole, che possono essere obliterate dall'erosione e dall'evoluzione del paesaggio. Per questo motivo è importante caratterizzare accuratamente la distribuzione delle frane, in termini di dimensione, in funzione della distanza dalla sorgente sismica. Sono stati analizzati sei terremoti in tutto il mondo che hanno innescato un significativo numero di frane (Finisterre 1993, Northridge 1994, Niigata 2004, Wenchuan 2008, Iwate 2008 and Tohoku 2011) per meglio comprendere le relazioni esistenti tra la distribuzione spaziale delle frane, l’accelerazione di picco al suolo (PGA), la distanza dalla sorgente, il relief e le litologie presenti nell’area. Si è osservata una forte relazione tra la PGA e la dimensione delle frane, mentre una la relazione tra la loro dimensione e la distanza dalla sorgente non è altrettanto chiara, ciò legato all’interazione tra diversi fattori quali ad esempio il relief e la litologia. Sono state realizzate e analizzate le curve magnitudo-frequenza (MFC) per differenti distanze dall’area sorgente attraverso varie metodologie: stimatore di massima verosimiglianza per distribuzioni di tipo potenza cumulate (Clauset et al, 2009), stimatore di massima verosimiglianza per distribuzioni di tipo potenza non cumulate, regressione ai minimi quadrati per funzioni di tipo potenza non cumulate in scala logaritmica e stimatore di massima verosimiglianza per la distribuzione Double Pareto. Dalle analisi si è potuto osservare un decrescere della densità spaziale delle frane con la distanza, ma un basso impatto della dimensione delle frane. Inoltre la funzione Double Pareto è stata scelta come miglior strumento per il fittaggio dei dati (Valagussa et al, 2014). Allo scopo di definire il rischio legato alle frane sismo-indotte è stata sviluppata una metodologia per la zonazione probabilistica quantitativa del rischio da frane da crollo (Valagussa et al, 2014). Il metodo è stato applicato e dimostrato nell’area del Friuli (Apli orientali) colpita da un terremoto di magnitudo 6.4 nel 1976. Quattro inventari sono stati realizzati sia tramite attività di terreno che da dati storici. La metodologia si basa sul vettore di rischio tridimensionale (RHVmod) le cui componenti includo l’energia cinetica, l’altezza di volo e la frequenza annua. I primi due valori sono calcolati per ogni cella del versante per mezzo del programma Hy-STONE. La frequenza annua è invece determinata moltiplicando la frequenza d’innesco annua per il numero di transiti simulati in ogni cella. La frequenza d’innesco annua è calcolata combinando l’area instabile, calcolata per 10 differenti scenari con differente frequenza annua di occorrenza sulla base di caratteristiche morfometriche e sismiche, e la curva magnitudo-frequenza relativa dei blocchi identificati da attività di terreno. Una serie di analisi discriminanti sono state condotte per determinare le variabili che controllano l’area in frana, sulla base degli inventari redatti e di DEMs a differenti risoluzioni (1 e 10m). L’analisi ha dimostrato il ruolo rilevante della curvatura nella definizione dell’area instabile. Per verificare la validità della mappa di PGA utilizzata nelle analisi, una nuova mappa è stata redatta sulla base delle Precarious Balanced Rocks identificate sul terreno.
Earthquakes have been recognized as a major cause of landsliding (Keefer, 1984), and landslides triggered by earthquakes have been documented since the IV century (Seed, 1968). The spatial distribution of earthquake-induced landslides around the seismogenetic source has been analysed to better understand the triggering of landslides in seismic areas and to forecast the maximum distance at which an earthquake, with a certain magnitude, can trigger landslides. However, when applying such approaches to old earthquakes one should be concerned about the undersampling of smaller landslides, which can be cancelled, by erosion and landscape evolution. For this reason, it is important to characterize carefully the size distribution of landslides as a function of distance from the earthquake source. I analysed six earthquakes in the world that triggered significant amount of landslides (Finisterre 1993, Northridge 1994, Niigata 2004, Wenchuan 2008, Iwate 2008 and Tohoku 2011) to better understand the relation between the spatial distribution of the landslides, the peak ground acceleration (PGA), the distance from the sources, the relief and the lithologies of the area. I observed a strong relationship between landslides size and PGA, while the relationship between the distance from the source and the landslide size distribution is not clear, due to the interaction of different factors such as relief and lithology. I also developed magnitude frequency curves (MFC) for different distances from the source area by using different methods, such as: the maximum likelihood estimator of cumulative power-law distribution (Clauset et al, 2009); the maximum likelihood estimator of non-cumulative power-law function; the least square regression of non-cumulative log power-law function and the maximum likelihood estimator of Double Pareto distribution. I observed a decrease of the spatial density of landslides with distance, with a small effect of the size of these landslides. I also identify the Double Pareto function as the best tool for the fitting of the data (Valagussa et al., 2014a). In order to define the hazard due to earthquake-induced landslides, I developed a methodology for quantitative probabilistic hazard zonation for rockfalls (Valagussa et al., 2014b). I applied and demonstrated the method in the area of Friuli (Eastern Italian Alps) that was affected by the 1976 Mw 6.5 earthquake. Four rockfall datasets have been prepared from both historical data and field surveys. The methodology relies on a three-dimensional hazard vector (RHVmod), whose components include the rockfall kinetic energy, the fly height, and the annual frequency. The values of the first two components are calculated for each location along the slope using the 3D rockfall runout simulator Hy-STONE. The rockfall annual frequency is assessed by multiplying the annual onset frequency by the simulated transit frequency. The annual onset frequency is calculated 2 through a procedure that combines the extent of unstable areas, calculated for 10 different seismichazard scenarios with different annual frequencies of occurrence, and the magnitude relativefrequency relationship of blocks as derived from the collected field data. For each annual frequency of occurrence, the unstable area is calculated as a function of morphometric and earthquake characteristics. A series of discriminant-analysis models, using the rockfall datasets and DEMs of different resolution (1 and 10 m), identified the controlling variables and verified the model robustness. In contrast with previously published research, I show that the slope curvature plays a relevant role in the computation of the unstable area. To ensure the validity of the peak ground acceleration used as seismic parameter in the discriminant function, I also try to define a map of PGA based on the precarious balanced rocks surveyed on the field.

Le concept de quasi-espèce, introduit par Manfred Eigen dans les années 70, décrit l'état d'équilibre d'une population subissant des forces de mutation et sélection. La plupart des modèles classiques présentant un phénomène de quasi-espèce sont déterministes et considèrent une population de taille infinie. L'objectif de cette thèse est d'étudier plusieurs modèles stochastiques, dont la taille de la population est finie, afin de montrer que le phénomène de la quasi--espèce est aussi présent dans ces modèles comme dans le modèles déterministes. Nous étudions en détail les modèles de Galton-Watson, Wright-Fisher et Moran. Nous confirmons que les trois modèles présentent un phénomène de quasi--espèce, et que la distribution de la quasi--espèce est la même pour les trois modèles, ainsi que pour le modèle original d'Eigen. De plus, nous décrivons explicitement la distribution de cette quasi--espèce pour le paysage de fitness à un pic, ainsi que pour des fonctions de fitness qui ne dépendent que de la distance de Hamming à la master sequence
Manfred Eigen introduced the concept of quasispecies in the early 70s, in order to describe the steady--state distribution of a population subject to mutation and selection forces. Most classical models showing a quasispecies phenomenon are deterministic and deal with a population of an infinite size. The aim of this thesis is to study several stochastic and finite--population models, and to show that a quasispecies phenomenon arises in these models too. We study in detail the Galton--Watson, Wright--Fisher and Moran models. We confirm that a quasispecies phenomenon is present in the three models, and that the distribution of this quasispecies is common to all three models as well as to Eigen's original model. Moreover, we describe explicitly the distributionof the quasispecies for the sharp peak landscape, as well as for fitness functions which depend only on the Hamming distance to the master sequence

Urbanization and economic development have important implications for many environmental processes including global climate change. Although there is evidence that urbanization depends endogenously on economic variables, long-term forecasts of the spatial distribution of population are often made exogenously and independent of economic conditions. A beta distribution for individual countries/regions is estimated to describe the geographical distribution of population using a 1° x 1° latitude-longitude global population data set. Cross-sectional country/regional data are then used to estimate an empirical relationship between parameters of the beta distribution and macroeconomic variables as they vary among countries/regions. This conditional beta distribution allows the simulation of a changing distribution of population, including the growth of urban areas, driven by economic forecasts until the year 2100.
Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).

This thesis investigates how changes in population size and spatial movements of individuals have shaped the distribution and abundance of neutral genetic variation in the arctic fox. This is done through mitochondrial and microsatellite DNA analyses on samples covering most of the species’ distribution, but with special emphasis on Scandinavia. On the species level, nucleotide diversity was relatively low, which indicated a historical expansion in population size in connection with the onset of the last Ice Age. It is thus possible that the glacial cycles have affected the arctic fox, and other cold-adapted species, in a way opposite to their effect on temperate species. Gene flow seemed to be high among arctic fox populations on a circumpolar scale, especially between populations where lemmings are the main food source, which could be explained by the spatial synchrony in lemming fluctuations. In Scandinavia, the arctic fox went through a severe demographic bottleneck in the beginning of the 20th century. Although some genetic variation was lost during this bottleneck, the loss was much smaller than expected, probably due to post-bottleneck gene flow from Russia. The arctic fox in Scandinavia is divided into four relatively isolated populations. Within each population, dispersal seemed to be high despite the high availability of empty territories close to natal dens, which supported the hypothesis that lemming fluctuations influence arctic fox dispersal. Genetic analyses on samples collected between 1989 and 2004 indicated an ongoing genetic drift and inbreeding within the Scandinavian populations. Furthermore, individual genetic variation was negatively associated with fitness, which could be attributed to an ongoing inbreeding depression. Analyses on faecal samples suggested that arctic foxes move higher up in the mountains and farther from the tree-line during summer compared to winter. This seasonal shift in distribution is probably caused by interspecific competition from the red fox, which is likely to be higher during summer due to red fox predation on arctic fox cubs. The results presented in this thesis have several implications for the conservation of the Scandinavian arctic fox. The finding of four isolated populations within Scandinavia and an ongoing inbreeding depression suggests that the risk of extinction is higher than previously thought. Conservation actions need to be taken in all populations to be effective, and could include genetic restoration through translocation.

The way malaria parasites are transmitted in space will have an influence on their genetic relationships. It can be expected that parasites collected within close geographic distances of each other would be more closely related than those across large geographic distances. Further to this, because malaria transmission is focal and heterogeneous in space, then the genetic relatedness between malaria parasites in these foci of malaria transmission would be greater within tightly clustered regions. Thus, using the level of genetic relatedness of these parasites would reveal how they are transmitted not only within these foci but at different geographic settings. This knowledge would offer insight on how malaria control methods can be effectively disseminated. In field settings malaria infections are polyclonal and each of the clones represented within these infections occur at different proportions. With the aid of genetic markers such as single nucleotide polymorphisms (SNPs) or microsatellites, parasite clonal genotypes can be identified. In this study, the genetic markers of choice are SNPs. Using a method that can quantify these SNPs representing the different clones occurring at different proportions in an isolate, then each of the clonal genotypes can be determined. Microsatellites were also used as additional markers in the study. In this thesis, 1.Genetic markers (SNPs) across the P. falciparum genome were identified (Chapter 3); 2. PyrosequencingTM was validated as a technique that would enable the identification of each genetically distinct clone represented in an infection by assigning proportions to the SNPs representing each genetically distinct clone and enabling the identification of parasite clonal genotypes in every isolate analysed. This was validated using laboratory prepared clone mixtures of P. falciparum. In addition; the progeny from a cross derived from genetically characterised 3D7 and HB3 isolates was analysed in preparation for the analysis of the field isolates (Chapter 4). , 4. In Chapter 5, field isolates were tested and clonal genotypes identified using both SNPs and microsatellites. A detailed population genetic analysis was also performed and finally in Chapter 6, evidence for correlation between the genetic relationships of these parasites and geographic distance was investigated. The results from field isolates summarised in this thesis were from analysis of 54 isolates; 7 samples collected from Cameroon, 13 from Kenya and 34 from Mali. The data consists of 13 SNPs analysed by PyrosequencingTM and 8 microsatellites. 84 clonal genotypes were identified by both genetic markers from the analysed isolates. Analysis of both SNPs and microsatellites revealed that microsatellites were more informative than the SNPs based on the observed allelic richness and heterozygosity (genetic diversity) across all loci analysed. The overall FST value was 0.061 using SNPs and 0.043 by microsatellites analysis. These values were low but consistent with what is typically observed in African P falciparum populations. Finally, analyses of the combined data set revealed that no statistically significant levels of spatial autocorrelation existed within the studied parasite populations. However, there was evidence of within host mixed parasite infections exhibiting a high level of genetic relatedness compared to between host infecting clones.

As one of the most promising pathways in the transition period towards the low carbon economy, a large scale implementation of electric vehicles (EV) is expected in the near future. Concentration of EV charging in a small area or within a short time will dramatically affect the load demand profile, especially the peak load in the distribution network. As a result, distribution transformers are facing hazards of shortened lifetime due to extra loads, and direct failures caused by potential overloads. Considering the large number of distribution transformers and the massive investment involved, the adaptability of the population of distribution transformers under future EV scenarios should be assessed. In this thesis, an assessment strategy for the future adaptability of distribution transformer population under EV scenarios is introduced. Assessing the adaptability is to understand the impact of the hot-spot temperature, loss-of-life, expected lifetime and failure probability of each individual in the distribution transformer population. Determination of hot-spot temperature of distribution transformers is essential for the assessment. In order to achieve accurate prediction of hot-spot temperatures under EV scenarios, thermal parameters should be refined for individual distribution transformers so that their thermal characteristics can be reflected more accurately than using the generic values recommended for all distribution transformers in the IEC loading guide. Two methods for the refinement are proposed in this thesis. One method is to curve-fit hot-spot temperatures measured in the extended heat run test; and the other is to calculate each parameter with developed equations in the loading guide with standard heat run test results. The assessment strategy is introduced and demonstrated on a group of selected distribution transformers from the population under three EV scenarios, i.e. Business as usual (BAU), High-range and Extreme-range scenarios, which represent 0%, 32% and 58.9% EV penetration levels respectively. Results show that EV charging would be less concerned on the acceleration of thermal ageing than the direct failure due to breakdown caused by decrease of dielectric strength in an event of bubbling. Since the peak load and hot-spot temperature under EV scenarios only last for a short time and would be compensated by low values during the rest time of a day, which eventually leads to a moderate thermal ageing. Occasionally, severe over-ageing can be caused by extremely high hot-spot temperatures, and the lifetime will be reduced to an unacceptable level. However, on such occasions, hot-spot temperatures would be high enough to trigger bubbling and reduce the dielectric strength of transformer's insulation system to a level that is incapable of undertaking the voltage stress, which eventually causes breakdown of transformers. In terms of the failure probability, results show that no distribution transformers are facing failure risks due to bubbling under BAU scenario. Failure starts under High-range scenario. If transformers possessing a failure probability over 50% are identified as high risk, then 13% of investigated transformers are at high risk under High-range scenario, while it increases to 39% under Extreme-range scenario. It is found that the failure probability is dominantly controlled by the peak load, other factors such as transformer age and installation conditions are less influential. A threshold peak load of around 1.5 p.u. is observed that distinguishes transformers in high risk from others under Extreme-range scenario. This observation could be applied to assist the asset management under future EV scenarios that the peak load of distribution transformers should be restricted below 1.5 p.u. to prevent potential failure due to bubbling.

Magister Philosophiae - MPhil (Statistics and Population Studies)
The purpose of the study was to examine the structural changes occurring in the patterns of spatial population distribution across South Africa over the period 1996-2016. The government in South Africa is perceived as being unsatisfied with the population distribution in the country. Therefore this research has given a better understanding of the settlement patterns in the country. The results can be utilized for regional and urban development planning to guide the government in achieving an even allocation of resources to strive towards a better balance of spatial patterns around the country. The polarisation reversal theory informed the study. In developing countries it is assumed that most of the population resides in rural areas and as time elapses we expect a more dispersed population with more of the population concentrated in urban areas as industrialization and urbanization evolves. The process usually starts with emergence of one or two major cities. The major cities then start to grow quicker than the other regions in the country. This results in unbalanced regional development across the country. This is then followed by the emergence of other smaller cities and towns. It is assumed that South Africa as a developing country will either move from a highly concentrated urban population with most of the population concentrated in one or two major cities to a more dispersed population where other smaller cities and towns are emerging,attracting more people threw migration or South Africa could move from a more dispersed population to a highly concentrated urban population. To test this assumption data will be derived from previous census and community surveys. Specifically the census taken in 1996, 2001,2011, the community survey of 2007 and 2016 respectively provided the data . Using the data sets, relevant statistical indicators of spatial population distribution were to quantify different trends over a period of time. These indicators includes pattern of urbanization and patterns of population settlement over the national territoriality. The results from the data analysis showed that some provinces were urbanizing faster than provinces. Some cities within provinces were growing faster than other cities. The highest concentration of the population is situated in one or two major cities. Smaller cities and towns around the country were growing faster than some major cities and also there is a decline in the rural population over the time period. From a spatial development view point, the insight into the patterns of population distribution can serve as a basis to create policies of which the main targets should be achieving balanced regional development, environmental sustainability, the development of smaller cites, towns and rural areas to slow the migration from these areas.

The aim of the thesis is to describe and analyse the population redistribution in Sweden at different geographical levels from the beginning of the 19th century to the end of the 20th century. The analysis is approached in three different ways. First, the redistribution at different geographical levels is analysed (papers I and II). Second, the changing accessibility between people (interpersonal accessibility) is analysed from the beginning of the 19th century to the end of the 20th century (paper II). Third, the impacts of fertility, mortality, internal migration, international migration and geographical variations in age composition on population distribution are analysed for the last decades (papers I, III and IV). Measurements of concentration have been used in order to analyse the changing population distribution. For the analysis of changing interpersonal accessibility the average population within the daily reach has been calculated for different times. In order to analyse the impacts of fertility, mortality, migration and geographical variations in age composition the actual redistribution of the population is compared with the redistribution generated by a number of counterfactual scenarios. To analyse the impact of international migration the changing distribution of the population in different immigrant groups is compared to the distribution of the Swedish population. Some conclusions drawn from the thesis are: 1. There is no overall trend in the population redistribution towards either concentration or dispersion. The redistribution pattern depends on the time perspective and the geographical level chosen. The population has been both concentrated and dispersed since the beginning of the 19th century. This applies to all investigated geographical levels. In the five identified phases of the redistribution the most common pattern is that concentration and dispersion of the population exist simultaneously on different geographical levels. The total effect of the redistribution between 1810 and 1990 is that today the population is more dispersed at macro-regional level, while it is more concentrated at local and regional level. 2. Based on assumptions about the daily reach, an average person today has access to about 100 times more people locally compared with the beginning of the 19th century. The most important process for the increased accessibility has been the redistribution of the population. The process that has had the least impact is the assumed increase in daily reach. However the importance of the investigated processes changes over time. Since 1950 the increasing reach has been the most important process. However, the rate by which interpersonal accessibility increases has slowed down since 1950. 3. The main demographic factor behind the redistribution since 1970 is the geographical differences in age composition and its effects on the natural population change. It is demonstrated that this factor lies behind the trend towards increasing concentration in Sweden, while the impact of migration affects the fluctuations from this trend to a greater extent. 4. The study shows that immigration concentrates the population, while the internal migration during the 1970s and periodically during the 1980s dispersed the population. However during the 1990s the internal migration has had a concentrating effect on the spatial distribution of the population.

Diss. (sammanfattning) Umeå : Umeå universitet, 2000, härtill 4 uppsatser

digitalisering@umu

This thesis contributes to the heuristic optimization of the p-median problem and Swedish population redistribution.   The p-median model is the most representative model in the location analysis. When facilities are located to a population geographically distributed in Q demand points, the p-median model systematically considers all the demand points such that each demand point will have an effect on the decision of the location. However, a series of questions arise. How do we measure the distances? Does the number of facilities to be located have a strong impact on the result? What scale of the network is suitable? How good is our solution? We have scrutinized a lot of issues like those. The reason why we are interested in those questions is that there are a lot of uncertainties in the solutions. We cannot guarantee our solution is good enough for making decisions. The technique of heuristic optimization is formulated in the thesis.   Swedish population redistribution is examined by a spatio-temporal covariance model. A descriptive analysis is not always enough to describe the moving effects from the neighbouring population. A correlation or a covariance analysis is more explicit to show the tendencies. Similarly, the optimization technique of the parameter estimation is required and is executed in the frame of statistical modeling.

The UK Census of Population, collected once every ten years, forms the main data source for demographic analysis. However, pre-2001, the smallest units at which this data was publicly available, known as enumeration districts in England, Wales and Northern Ireland, were irregular and diverse, and these often did not correspond to other survey data sets. For this reason, attempts to integrate these data sources have proved difficult, thus necessitating the urgent development of new methods capable of modelling population distribution with greater accuracy. Within recent years an explosion of georeferenced data has become readily available to both the academic and commercial world, including vector data sets from the Ordnance Survey (OS), specifically - OS Land-Line.Plus and OS MasterMap. These highly detailed vector-based data sets collected and available at scales from 1:1, 250 to 1:10,000, contain the location of many features of the built and natural environment. These features which include road centrelines and building outlines may prove to be appropriate ancillary data sets to better inform the distribution of population. Five regression-based dasymetric models were constructed using combinations of these vector data sets to predict population at a variety of spatial scales and locations in an area of south Leicestershire, UK. This study area, which was split into a source zone of known population and a target zone of unknown population, was chosen due to its diverse mix of both urban and rural areas. Results using the vector-based models were subsequently compared statistically to those from a Landsat dasymetric model. This research not only reveals the varying degrees of success achieved by the newly developed methods, but perhaps more notably so, the superior results obtained by the more complex models in relation to those from the already extensively research Landsat based approach or the simple areal interpolation method.

Albatrosses and petrels (Order Procellariiformes) are renowned for the huge distances they can cover at sea, and since the advent of tracking technology their pelagic lifestyles are generally well studied. However, tropical species are under-represented in the literature, and may be particularly flexible in their behaviour since tropical oceans are oligotrophic and prey availability is often patchily distributed. Round Island petrels breed in such an environment off the coast of Mauritius in the south-western Indian Ocean. Whilst originally identified as Trindade petrels (Pteromdroma arminjoniana), it has recently been revealed that this population is in fact a mixed, hybridizing population with at least two additional species, namely the Kermadec and Herald petrels (P. neglecta and P. heraldica). However, to date no research has been conducted on the colony-based at-sea distribution of these petrels, or how their mixed ancestry may influence their distribution at sea. In this thesis I firstly explore the possibility that Round Island may not be the only point of contact between these species and find that migration and introgression between wide-ranging Pterodroma may be more common than previously thought. I go on to develop a novel data cleaning method to enable the analysis of geolocation data from Round Island petrels, and use that data to describe for the first time their at-sea distribution and the extensive within-population variation in these patterns. Finally, I use a combination of tracking and microsatellite genotype data to ultimately weigh the influence of individual genetic background and the wider seasonal environment on distribution variability around the breeding colony. The Round Island petrel population is a stronghold where seabird populations globally are in decline. This thesis adds to the limited literature on ecology of tropical petrel species, and highlights the importance of considering behavioural and genetic diversity in future conservation plans.

L'histoire de la théorie des matrices aléatoires de grande taille remonte à l'élaboration de la mécanique quantique dans les années 1940 et 1950. Depuis, l'analyse spectrale des matrices aléatoires de grande taille a été menée par les mathématiciens, les probabilistes et les statisticiens. Pendant les dernières décennies, cette théorie trouve de plus en plus d'applications dans divers domaines. Un problème urgent a aussi apparu en statistique concernant l'estimation d'un modèle avec des données de grande dimension. Cette thèse traite le problème d'estimation d'une distribution spectrale de population en partant des matrices de covariances empiriques. Notre étude est basée sur la relation entre les moments de la distribution spectrale de population et les moments de la distribution spectrale limite. Lorsque l'ordre du modèle est connu, nous proposons un estimateur consistant des paramètres du modèle. Au contraire, lorsque l'ordre du modèle est inconnu, nous utilisons la méthode de cross-validation pour sélectionner l'ordre du modèle
The history of random matrix theory in large dimensions can be traced back to the development of quantum mechanics in the 1940's and the early 1950's. Soon the limiting spectral analysis of large dimensional random matrices were started by mathematicians, probabilists and statisticians. In recent decades, the limiting spectral distribution theory become more and more widely used in various applications. A pressing problem appears also in statistics, that is, to deal with high-dimensional data using the theory of large dimensional random matrices. This thesis considers the problem of estimation of a population spectral distribution from an observed sample covariance matrix. We study the problem using a relationship between the moments of the population spectral distribution and the moments of limiting spectral distribution. When the model order is known, we propose a consistent estimator for model parameters. On the contrary, when the model order is unknown, we propose a cross-validation procedure to select the model order

Many bird populations are known to show strong territoriality as well as high site fidelity during breeding. The Common Nightingale (Luscinia megarhynchos) is one of many such migratory species that annually occupies the same favourable habitat. Especially dominant males prefer to breed in the same area every year, and high fidelity probably assures high breeding success. This study aims to investigate breeding biology, population size and spatial distribution of nightingales at a small area in Yalincak within the METU campus grounds (Ankara, Turkey). From 2003 to 2005, birds were captured and marked with metal or colour rings or radio tags for monitoring. Analyses were carried out on 77 individuals, including ringing data from the previous two years. Phenology of the study population was characterized by early arrival of males in late April, followed one week later by females. Nesting immediately followed and the first young fledged in early June. Second broods were also recorded. Most birds apparently left for the south within August. The population in the 2.65 ha large area was estimated to be about 20-25 individuals. However, only 2-4 breeding territories were present and a large proportion of floaters existed. Territory sizes were smaller than reported elsewhere. Annual survival rate was 0.424 &
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0.121. Contrary to previous knowledge, taxonomically the Yalincak population belonged to subspecies africana although more westerly subspecies could be recorded during migration. This study revealed the importance of small but productive biotopes as important breeding habitats for passerines. It also showed that a few highly successful individuals may contribute out of proportion to the next generation.

The present thesis provides new information about pelagic decapod crustaceans, specially so concerning the Mediterranean pasiphaeids. Remarkable differences in the pattern of distributions of the pasiphaeids were observed according to the influence of Atlantic waters. Overall both abundance and biomass of the pasiphaeids in Alboran Sea was higher than in the rest of the Iberian Mediterranean populations. The depth on which the pasiphaeids started to occur in appreciable density was also shallower in the Alboran Sea where the P. sivado presented the widest depth range of distribution as well as the biggest size of first maturity of females. This size was progressively smaller with increasing distance from the Atlantic water source, i.e the Gibraltar Strait area. Overall the two species presented a size structure that changed with depth, with younger individuals occupying shallower depths and biggest adults occupying deeper bathymetries. P. multidentata juveniles were only observed in the Catalan Sea while they were absent in the Alboran Sea. Size and morphological dimorphism of P. sivado were reported for the first time in the present thesis. All the five pleopods of females were thinner and more elongated than male pleopods, which in turn were rounded anteriorly and had robust shapes. A critical size from which the population sex ratio biases changed from females to males dominance was found in all P. sivado populations of the Mediterranean Iberian coast. This critical size was different and progressively larger again from populations nearest the Gibraltar Strait versus those placed in the Catalan Sea, in concordance with the female first maturity size gradient. The present thesis also provides a first attempt to investigate the influence of the Gibraltar Strait on the genetic population structure of the species by using congener benthopelagic shrimps that dwell in different depth strata. The Gibraltar Strait was shown to be a strong and unique geographical barrier to the genetic flux of both P. sivado and P. multidentata, due the presence of a marked genetic structure characterized by two main haplotypes: one Atlantic and another one Mediterranean. Other new information related to the phylogeny of the genus Pasiphaea was that P. sivado a much higher genetic divergence when compared to the rest of pasiphaeid species analysed, indicating that several genetic subgroups do occur within the genus Pasiphaea. The study of the pelagic decapod community in the waters around the island of Mallorca, placed between the Algerian and the Catalano-Balearic basins, showed the occurrence of two main assemblages: one above the shelf break and another one above the middle slope. The shelf community was characterized by the dominance of almost transparent species, such as Sergestes arcticus, the species that reached the greatest abundances, and P. sivado that was omnipresent in all pelagic strata. The novel registration of Chlorotocus crassicornis and Plesionika heterocarpus in the pelagic realm were restricted to the shelf-break at the Deep Scattering Layer. The red body species Gennadas elegans, Pasiphaea multidentata, and Sergia robusta, were restricted to the middle slope. No significant differences concerning the sampling geographic area or seasonality were found. Actually, the decapod pelagic community of the Balearic Sea was mainly structured by both the geomorphology (and associated hydrographic characteristics of the shelf/slope transition) and the influence of light in the water column. No decapod crustacean species occurred in epipelagic daytime samples. Size analysis showed the occurrence of species-specific patterns concerning the size/age movements into the water column throughout the day-night cycle. Moreover, the present work clearly confirms the presence of adult P. multidentata in the water column, evidencing that the adult fraction of the population has also the ability to perform vertical migrations.
Aquesta tesi presenta nova informació sobre crustacis decàpodes pelàgics, principalment sobre els pasifèids presents a la Mediterrània: Pasiphaea sivado i Pasiphaea multidentat. S’han trobat diferències importants en les pautes de distribució dels pasifèids en relació a la influència de les aigües atlàntiques a la Mediterrània. Globalment, tant l’abundància com la biomassa dels pasifèids del Mar d’Alboran van ser superiors que a la resta de poblacions mediterrànies mostrejades. La profunditat a la qual es comencen a trobar les diferents espècies de pasifèids de la Mediterrània és també menor a la Mar d’Alboran, on P. sivado va presentar el major rang de distribució en fondària, així com també la més gran talla de maduresa en femelles. Aquesta talla es va fent progressivament menor a mesura que augmenta la distància a la font d’aigües atlàntiques, és a dir, de la zona de l’Estret de Gibraltar. Ambdues espècies van presentar una estructura de talles variable en funció de la profunditat, amb individus juvenils ocupant profunditats més somes que els adults. Addicionalment, juvenils de P. multidentata només es van observar al Mar Català, mentre que van ser absents del Mar d’Alboran, fet que suggereix l’existència de diferències important en l’estacionalitat de la reproducció i/o de la dinàmica de les poblacions. L’existència de dimorfisme sexual entre mascles i femelles de P. sivado es reporta per primera vegada en aquesta tesi, així com de diferències significatives en l’estructura de talles entre sexes. Els cinc pleopodis de les femelles adultes són clarament més fins i allargats que els pleopodis dels mascles adults, els quals són arrodonits anteriorment i tenen una forma més robusta. S’ha detectat una talla crítica a partir de la qual la proporció de sexes de les poblacions canvien cap a una dominància significativa dels mascles. Aquesta talla disminueix progressivament i significativa des de la població més propera a l’Estret de Gibraltar, la del Mar d’Alboran, passant per la població d’Alacant, fins a la població del Mar Català, en concordança amb els canvis observat a la talla de maduresa de les femelles. Aquesta tesi també presenta una primera aproximació a investigar el paper de l’Estret de Gibraltar sobre l’estructura genètica de les poblacions de pasifèids, utilitzant les dues espècies utilitzades en els capítols precedents, les quals representen espècies congenèriques, simpàtriques geogràficament, però amb una marcada distribució batimètrica diferencial. Les anàlisis efectuades han mostrat que l’Estret de Gibraltar constitueix una forta i única barrera geogràfica per a la connectivitat genètica entre les poblacions d’ambdues espècies situades a una banda i altra de l’Estret. En ambdues espècies s’ha detectat l’existència d’una marcada estructuració genètica caracteritzada per dos haplotips principals, un que es troba només en poblacions atlàntiques, i un altre únicament en poblacions mediterrànies. Basant-se també en característiques genètiques, s’ha obtingut nova informació referent a la filogènia del gènera Pasiphaea, que mostra l’existència d’una important divergència genètica entre P. sivado i la resta d’espècies de la família Pasiphaeidae de les quals en l’actualitat es té informació, fet que indica que dins del gènere Pasiphaea es troben diferents subgrups genètics ben delimitats. L’estudi de la comunitat de crustacis decàpodes pelàgics en aigües al voltant de l’illa de Mallorca, localitzada entre les conques Algeriana i Catalano-Balear ha mostrat la presència de dues comunitats faunístiques diferenciades, no geogràficament sinó en funció de la batimetria: una en aigües localitzades sobre el límit plataforma-talús i una altra al damunt del talús mig. La comunitat més soma, la del límit plataforma-talús, es va caracteritzar per la dominància d’espècies pràcticament transparents, com Sergestes arcticus, l’espècie que va assolir les abundàncies més elevades, i Pasiphaea sivado, espècie omnipresent a tots els nivells pelàgics mostrejats. Els registres a l’ambient pelàgic de Chlorotocus crassicornis i Plesionika heterocarpus, no citades anteriorment en aquest ambient, es van restringir a les capes de difusió profunda del límit plataforma-talús. Les espècies de coloració més vermellosa (Gennadas elegans, Pasiphaea multidentata i Sergia robusta) es van localitzar únicament sobre fons del talús mig. No es van trobar diferències significatives en funció de la localització geogràfica o de les dues estacions de l’any mostrejades. Es considera que la comunitat de crustacis decàpodes pelàgics del Mar Balear està fonamentalment estructurada tant per la geomorfologia i característiques hidrogràfiques associades a la transició entre la plataforma i el talús continentals, com per la influència de la llum a la columna d’aigua. No es van trobar espècies de crustacis decàpodes en mostres epipelàgiques preses durant el dia. L’anàlisi de les talles dels individus capturats ha mostrat que els moviments de les diferents classes de talla (edat) a través de la columna d’aigua varien al llarg del cicle dia-nit d’una manera diferencial en funció de cada espècie. Adicionalment, aquest treball confirma clarament que la fracció adulta de la població de Pasiphaea multidenta presenta també la capacitat de dur a terme migracions verticals. S’és conscient que existeixen avui dia encara molts forats en el coneixement de l’autoecologia i cicle vital tant dels pasifèids com de la resta de decàpodes pelàgics. Moltes qüestions romanents per a comprendre millor l’estructura i dinàmica de poblacions, distribució i filogènia, podrien ser millor enteses i discutides si hagués més coneixença sobre el cicle vitat, els estadis larvaris i post-larvaris, així com sobre la dispersió i connectivitat de les poblacions. L’elevat esforç de mostreig, i el seu alt cost associat, són encara avui dia una de les raons principals de l’escassetat d’informació disponible.

INTRODUCTION Although the need for comprehensive management of patients with multiple co-occurring conditions has been highlighted, policies and guidelines are still focused on the management of individual diseases. Thus, a better understanding of multimorbidity is considered fundamental to the development of new preventive and management strategies. OBJECTIVES 1. To examine the distribution of chronic conditions and multimorbidity patterns in the Spanish older adult population. 2. To assess the association between individual physical conditions (e.g., diabetes, angina) and the prevalence of mental disorders in the population over 50 years of age. 3. To evaluate the relationship between physical multimorbidity and the prevalence of mental disorders in the Spanish population over 50 years of age. 4. To study the individual and cumulative impact of chronic physical conditions on visual impairment in the population over 50 years old. 5. To analyze the relationship between visual impairment and the presence of mental disorders and cognitive impairment in the population over 50 years old. 6. To explore the individual and cumulative impact of chronic physical and mental conditions on quality of life and disability in the population over 50 years of age. 7. To examine general trends in quality of life and disability across gender in relation to the individual and cumulative effects of chronic conditions. METHODS Data from this cross-sectional study were collected from the Collaborative Research on Ageing in Europe (COURAGE) Project. A total of 4,583 participants from Spain were included; 3,625 aged over 50. An exploratory factor analysis was conducted to detect multimorbidity patterns in the population over 50 years of age. Crude and adjusted binary logistic regressions were performed to identify the associations between physical and mental conditions. Crude and adjusted binary logistic regressions were conducted to assess the associations between visual impairment and chronic physical conditions, physical multimorbidity, mental disorders and cognitive impairment. Finally, crude and adjusted multiple linear regressions were performed to detect associations between chronic conditions and quality of life, and between chronic conditions and disability. Separate models were used to assess the importance of the increasing number of diseases on quality of life and disability, adjusting for same covariates. Additional analogous regressions were performed for males and females to assess gender trends. RESULTS Three multimorbidity patterns emerged: ‘cardio-respiratory’ (angina, asthma, chronic lung disease), ‘mental-arthritis’ (arthritis, depression, anxiety) and the ‘aggregated pattern’ (angina, hypertension, stroke, diabetes, cataracts, edentulism, and arthritis). All conditions were related to at least one pattern. Angina, arthritis, asthma, chronic lung disease and the number of physical conditions were associated with depression [OR 2.01 (1.40,2.90); OR 1.62 (1.19,2.21); OR 1.86 (1.31,2.64); OR 2.66 (1.84,3.86); OR for 3+ diseases 4.38 (2.31,8.33)]. Angina and the number of physical conditions were associated with a higher risk of anxiety [OR 3.39 (1.84,6.22); OR for 3+ diseases 5.23 (1.76,15.53)]. The number of chronic physical conditions was found to be associated with poorer results in both distance and near visual acuity [OR for 3+ diseases 1.75 (1.38,2.23); OR for 3+ diseases 1.69 (1.27,2.24)]. Arthritis, stroke and diabetes were associated with poorer distance visual acuity results [OR 1.79 (1.46,2.21); OR 1.59 (1.05,2.42); OR 1.27 (1.01,1.60)]. Only stroke was associated with near visual impairment [OR 3.01 (1.86,4.87)]. With regard to mental health, poor subjective distance and near visual performance was associated with depression [OR 1.61 (1.14,2.27); OR 1.48 (1.03,2.13)]. Both objective and subjective poor distance and near visual acuity were associated with worse cognitive functioning. All chronic conditions except hypertension were statistically associated with poor results in quality of life and disability. Depression, stroke and anxiety were found to have the greatest impact on disability [β 15.70 (13.62,17.77); β 12.15 (8.08,16.22); β 11.17 (2.49,19.86)] and quality of life [β -14.00 (-15.85,-12.14); β -8.16 (-11.77,-4.55), β -7.82 (-11.57,-4.08)]. The number of chronic conditions was associated with substantially lower quality of life [β for 4+ diseases: -18.10 (-20.95,-15.25)] and greater disability [β for 4+ diseases: 27.64 (24.99,30.29)]. In general, women suffered from higher rates of multimorbidity and poorer results in quality of life and disability. Effect size across gender resulted in small-moderate values. CONCLUSIONS 1. Multimorbidity is present in a large proportion of the older Spanish population, especially in those aged over 50. The prevalence of multimorbidity affects more than half of men and over two-thirds of women over 65 years. Chronic conditions tend to appear in certain multimorbidity patterns: “cardio-respiratory” (angina, asthma, COPD), “mental arthritis” (arthritis, anxiety, depression), “aggregate pattern” (angina, cataract, hypertension, edentulism, diabetes, arthritis, stroke). 2. With regard to the analysis of the impact of individual physical diseases on mental health, a higher risk of depression is present in people with asthma, angina, COPD and arthritis, whereas only angina is associated with anxiety. 3. The number of chronic conditions is greatly associated with the diagnosis of depression and anxiety. 4. Visual impairment is common in the Spanish older population. Stroke, arthritis and diabetes are individually associated with worse distance visual acuity, while stroke is associated with worse near visual acuity. The number of physical conditions is greatly associated with worse distance and near visual acuity. 5. Subjective distance visual acuity problems are related to a higher risk of depression, while no measure of visual acuity is associated with changes in the prevalence of anxiety. All measures of visual impairment (distance/near and objective/subjective) are related to impaired cognitive functioning. 6. All chronic conditions assessed (angina, anxiety, arthritis, asthma, cataract, COPD, depression, diabetes, edentulism, stroke), except for hypertension, impact negatively on disability and quality of life in the Spanish older population. Stroke and mental disorders (depression, anxiety) are the conditions that have the strongest impact on these outcomes. Conditions with fewer symptoms (diabetes, edentulism, cataract) tend to have a lower impact on health outcomes than those with more symptoms (angina, COPD, arthritis). The number of chronic conditions impacts greatly both on quality of life and disability. 7. Women have slightly poorer results in quality of life and disability than men. Individually, some conditions affect quality of life and disability only in men or women. The effect of the number of chronic conditions is important in both sexes.
INTRODUCCIÓN Entender mejor la relación entre las diferentes condiciones crónicas es fundamental para el desarrollo de nuevas estrategias preventivas y de manejo de estos pacientes. OBJETIVOS - Examinar los patrones de multimorbilidad en la población adulta española y la relación entre patologías físicas y mentales. - Analizar la relación entre la discapacidad visual y la presencia de problemas mentales y deterioro cognitivo. - Explorar el impacto de las condiciones crónicas físicas y mentales sobre la calidad de vida y la discapacidad, y examinar las tendencias por género en relación a estas asociaciones. MÉTODOS Los datos de este estudio transversal provienen del estudio “Collaborative Research on Ageing in Europe” (COURAGE). Se incluyeron un total de 4,583 participantes de España, 3,625 por encima de los 50 años de edad. Se utilizó la técnica de factor de análisis exploratorio para detectar patrones de multimorbilidad en la población mayor de 50 años. Se realizaron regresiones logísticas crudas y ajustadas para identificar las asociaciones entre: a) patologías físicas y mentales; b) el déficit visual y las condiciones físicas, la multimorbilidad física, los problemas mentales y la función cognitiva. Se realizaron regresiones lineares múltiples para detectar las asociaciones entre las condiciones crónicas y la calidad de vida, así como de entre las condiciones crónicas y la discapacidad. De forma análoga, se realizaron estos análisis para hombres y mujeres con el objetivo de evaluar las tendencias por género. RESULTADOS Se detectaron tres patrones de multimorbilidad: “cardio-respiratorio” (angina, asma, EPOC), “mental-artritis” (artritis, depresión, ansiedad) y el “patrón agregado” (angina, hipertensión, ictus, diabetes, cataratas, edentulismo y artritis). Angina, artritis, asma, EPOC y el número de condiciones físicas se asociaron con depresión después de ajustar por covariables [OR para 3+ condiciones 4.38 (2.31,8.33)]. Por su parte, la angina y el número de condiciones físicas se asociaron a un mayor riesgo de ansiedad [OR para 3+ condiciones 5.23 (1.76,15.53)]. El número de condiciones crónicas físicas se asoció con malos resultados de agudeza visual de lejos y de cerca [OR para 3+ condiciones 1.75 (1.38,2.23); OR para 3+ condiciones 1.69 (1.27,2.24)]. Artritis, ictus y diabetes se asociaron a malos resultados de agudeza visual de lejos. Solo el ictus se asoció a peores resultados de agudeza visual de cerca. En relación a los problemas mentales, una peor agudeza visual subjetiva de lejos y de cerca se asoció a depresión. Tanto los problemas visuales a nivel objetivo (agudeza visual), como subjetivos resultaron asociados con peor función cognitiva (tanto para visión de lejos como de cerca). Todas las condiciones crónicas excepto la hipertensión resultaron asociadas con peores resultados en calidad de vida y discapacidad. Depresión, ictus y ansiedad fueron las condiciones con mayor impacto sobre discapacidad y calidad de vida. El número de condiciones crónicas se relacionó fuertemente con peores resultados en calidad de vida [β 4+ condiciones: -18.10 (-20.95,-15.25)] y mayor discapacidad [β 4+ condiciones: 27.64 (24.99,30.29)]. En general las mujeres sufrieron mayores tasas de multimorbilidad y peores resultados a nivel de discapacidad y calidad de vida. Se calculó el efecto del tamaño para estas variables entre hombres y mujeres, resultando en valores pequeños-moderados. CONCLUSIONES - Las condiciones crónicas se presentan en determinados patrones de multimorbilidad: “cardio-respiratorio” (angina, asma, EPOC), “mental-artritis” (artritis, ansiedad, depresión), “patrón agregado” (angina, cataratas, hipertensión, edentulismo, diabetes, artritis, ictus). A nivel individual, angina, artritis, asma y EPOC están asociados a un mayor riesgo de depresión. Solamente angina se relaciona con ansiedad. El número de condiciones crónicas se asocia fuertemente con el diagnóstico de depresión y ansiedad. - Ictus, artritis y diabetes se asocian con peor agudeza visual de lejos, mientras que el ictus también se relaciona con peor agudeza visual de cerca. El número de condiciones físicas se asocia fuertemente a peores resultados de agudeza visual de lejos y de cerca. Los problemas subjetivos de la visión de lejos se relacionan con un mayor riesgo de depresión, pero no de ansiedad. Los problemas visuales se asocian a deterioro cognitivo. - Todas las condiciones crónicas evaluadas, excepto hipertensión, afectan la discapacidad y la calidad de vida de forma negativa. El ictus y los problemas mentales (depresión, ansiedad) son las condiciones con el efecto más importante en estos resultados. Las condiciones con menos síntomas (diabetes, edentulismo, catarata) ejercen una menor influencia sobre estas variables comparado con aquellas más sintomáticas (angina, EPOC, artritis). El número de condiciones crónicas afecta de forma intensa la calidad de vida y discapacidad. Las mujeres tienen resultados moderadamente peores que los hombres a nivel de calidad de vida y discapacidad. Individualmente, algunas condiciones afectan la calidad de vida o discapacidad sólo a las mujeres o a los hombres.
INTRODUCCIÓ Entendre millor la relació entre les diferents condicions cròniques és fonamental pel desenvolupament de noves estratègies preventives i de maneig d'aquests pacients. OBJECTIU - Examinar els patrons de multimorbilitat en la població adulta espanyola i la relació entre patologies físiques i mentals. - Analitzar la relació entre la discapacitat visual i la presència de problemes mentals i deteriorament cognitiu. - Explorar l'impacte de les condicions cròniques físiques i mentals sobre la qualitat de vida i la discapacitat, i examinar les tendències per gènere en relació a aquestes associacions. MÈTODE Les dades d'aquest estudi transversal provenen de l'estudi "Collaborative Research on Ageing in Europe" (COURAGE). Es van incloure un total de 4,583 participants d'Espanya, 3,625 per sobre dels 50 anys d'edat. Es va utilitzar la tècnica de factor d'anàlisi exploratòria per detectar patrons de multimorbilitat en la població major de 50 anys. Es van realitzar regressions logístiques crues i ajustades per identificar les associacions entre: a) patologies físiques i mentals; b) el dèficit visual i les condicions físiques, la multimorbilitat física, els problemes mentals i la funció cognitiva. Es van realitzar regressions lineals múltiples per detectar les associacions entre les condicions cròniques i la qualitat de vida, així com d'entre les condicions cròniques i la discapacitat. De forma anàloga, es van realitzar aquestes anàlisis per a homes i dones amb l'objectiu d'avaluar les tendències per gènere. RESULTATS Es van detectar tres patrons de multimorbilitat: "cardio-respiratori" (angina, asma, MPOC), "mental-artritis" (artritis, depressió, ansietat) i el "patró agregat" (angina, hipertensió, ictus, diabetis, cataractes, edentulisme i artritis). Angina, artritis, asma, MPOC i el nombre de condicions físiques es van associar amb depressió després d'ajustar per covariables [OR per 3+ condicions 4.38 (2.31,8.33)]. Per la seva banda, l'angina i el nombre de condicions físiques es van associar a un major risc d'ansietat [OR per 3+ condicions 5.23 (1.76,15.53)]. El nombre de condicions cròniques físiques es va associar amb mals resultats d'agudesa visual de lluny i de prop [OR per 3+ condicions 1.75 (1.38,2.23); OR per 3+ condicions 1.69 (1.27,2.24)]. Artritis, ictus i diabetis es van associar a mals resultats d'agudesa visual de lluny. Només l'ictus es va associar a pitjors resultats d'agudesa visual de prop. En relació als problemes mentals, una pitjor agudesa visual subjectiva de lluny i de prop es va associar amb depressió. Tant els problemes visuals a nivell objectiu (agudesa visual), com subjectius van resultar associats amb pitjor funció cognitiva (tant per a visió de lluny com de prop). Totes les condicions cròniques excepte la hipertensió van resultar associades amb pitjors resultats en qualitat de vida i discapacitat. Depressió, ictus i ansietat van ser les condicions amb major impacte sobre discapacitat i qualitat de vida. El nombre de condicions cròniques es va relacionar fortament amb pitjors resultats en qualitat de vida [β 4+ condicions: -18.10 (-20.95, -15.25)] i major discapacitat [β 4+ condicions: 27.64 (24.99,30.29)]. En general les dones van patir majors taxes de multimorbilitat i pitjors resultats a nivell de discapacitat i qualitat de vida. Es va calcular l'efecte de la mida per a aquestes variables entre homes i dones, resultant en valors petits-moderats. CONCLUSIONS - Les condicions cròniques es presenten en determinats patrons de multimorbilitat: "cardio-respiratori" (angina, asma, MPOC), "mental-artritis" (artritis, ansietat, depressió), "patró agregat" (angina, cataractes, hipertensió, edentulisme , diabetis, artritis, ictus). A nivell individual, angina, artritis, asma i MPOC estan associats a un major risc de depressió. Només angina es relaciona amb ansietat. El nombre de condicions cròniques s'associa fortament amb el diagnòstic de depressió i ansietat. - Ictus, artritis i diabetis s'associen amb pitjor agudesa visual de lluny, mentre que l'ictus també es relaciona amb pitjor agudesa visual de prop. El nombre de condicions físiques s'associa fortament a pitjors resultats d'agudesa visual de lluny i de prop. Els problemes subjectius de la visió de lluny es relacionen amb un major risc de depressió, però no d'ansietat. Els problemes visuals s'associen a deteriorament cognitiu. - Totes les condicions cròniques avaluades, excepte hipertensió, afecten la discapacitat i la qualitat de vida de forma negativa. L'ictus i els problemes mentals (depressió, ansietat) són les condicions amb l'efecte més important en aquests resultats. Les condicions amb menys símptomes (diabetis, edentulisme, cataracta) exerceixen una menor influència sobre aquestes variables comparat amb aquelles més simptomàtiques (angina, MPOC, artritis). El nombre de condicions cròniques afecta de forma intensa la qualitat de vida i discapacitat. Les dones tenen resultats moderadament pitjors que els homes a nivell de qualitat de vida i discapacitat. Individualment, algunes condicions afecten la qualitat de vida o discapacitat només a les dones o als homes.

Studying the dynamics of pathogen transmission within wildlife populations presents an array of challenges. Where populations are socially structured, this can influence parasite transmission, impacting on the effectiveness of disease management strategies. In this thesis, I focus on a well-studied social mammal, the European badger (Meles meles) which is a key wildlife reservoir of a disease of economic importance; bovine TB (caused by infection with Mycobacterium bovis). The social structuring, characteristic of high density badger populations, is of well-established importance in the transmission of bovine TB and has resulted in unexpected management outcomes. However, little is known about the role of kin structure or host genotype on transmission dynamics. In this thesis, I combine traditional spatial epidemiology and ecological analysis of a well-studied badger population with more novel genetic and genomic approaches. Firstly, I investigate the role of kin structure within badger social groups in determining early life infection risk (Chapter 3). Using host genotype data, I demonstrate that cubs who are related to infected adults experience enhanced infection risks. I then explore the role of badger genotype on outcomes of M. bovis exposure and demonstrate that inbred badgers are more likely to show evidence of progressive infection (Chapter 4). Where the social structure of badgers is stable and unmanaged, this is predicted to result in a stable spatial distribution of M. bovis infection. Motivated by an observation of change in the spatial distribution of M. bovis infection in the study population, in the absence of management, I characterise the attrition of a spatially stable infection distribution (Chapter 5). To explore the drivers of this, I detect changes in the genetic population structure (Chapter 6) and present evidence that the population has experienced a period of demographic flux. Finally, I use a novel dataset generated by whole genome sequencing of M. bovis isolates and present evidence of spatial spread of M. bovis infection across the study population (Chapter 7). To conclude, I discuss how my findings demonstrate how genetic and genomic approaches can complement traditional wildlife epidemiology approaches, how they contribute to our understanding of heterogeneity in transmission dynamics and discuss their implications for wildlife disease management.

Thesis: Ph. D., Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution), February, 2021
Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 119-135).
The early life stages of marine fishes play a critical role in population dynamics, largely due to their high abundance, high mortality, and ease of transport in ocean currents. This dissertation demonstrates the value of combining larval data, collected in the field and the laboratory, with model simulations. In Chapter 2, analyses of field observations of ontogenetic vertical distributions of coral reef fish revealed a diversity of behaviors both between and within families. In Caribbean-wide particle-tracking simulations of representative behaviors, surface-dwelling larvae were generally transported longer distances with greater population connectivity amongst habitat patches, while the evenly-distributed vertical behavior and downward ontogenetic vertical migration were similar to one another and led to greater retention near natal sites. However, hydrodynamics and habitat availability created some local patterns that contradicted the overall expectation.
Chapter 3 presents evidence of tuna spawning inside a large no-take marine protected area, the Phoenix Islands Protected Area (PIPA). Despite variation in temperature and chlorophyll, the larval tuna distributions were similar amongst years, with skipjack (Katsuwonus pelamis) and Thunnus spp. tunas observed in all three years. Backtracking simulations indicated that spawning occurred inside PIPA in all 3 study years, demonstrating that PIPA is protecting viable tuna spawning habitat. In Chapter 4, several lines of larval evidence support the classification of the Slope Sea as a major spawning ground for Atlantic bluefin tuna with conditions suitable for larval growth. The abundance of bluefin tuna larvae observed in the Slope Sea aligns with typical observations on the other two spawning grounds.
Age and growth analyses of bluefin tuna larvae collected in the Slope Sea and the Gulf of Mexico in 2016 did not show a growth rate difference between regions, but did suggest that Slope Sea larvae are larger at the onset of exogenous feeding. Collected larvae were backtracked to locations north of Cape Hatteras and forward tracked to show that they would have been retained within the Slope Sea until the onset of swimming. As a whole, this thesis presents valuable contributions to the study of larval fishes and the attendant implications for marine resource management.
by Christina M. Hernández.
Ph. D.
Ph.D. Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Department of Biology; and the Woods Hole Oceanographic Institution)

A simulation matrix population model of a small population of wrens (Troglodytes troglodytes) is presented. The field work methods used to obtain and analyse the demographic rates are provided. This includes a description of the use of miniature radio tags to track juvenile (post-fledging) survival and dispersal, and capture mark recapture analysis of an eight year dataset to estimate adult survival rates, taking into account environmental variation and density dependence. Age related reproductive rates were obtained from detailed nest surveys. Using these demographic rates (means and variances), and information on density dependence in survival and breeding, a simulation matrix model was developed using Matlab (The MathWorks, Inc.). The operation of this model and its outputs are explained in detail, with particular reference to the methods employed to incorporate both density dependent survival and reproduction and environmental and demographic stochasticity. This model is then used to illustrate how, under plausible conditions of density dependence and stochasticity, large discrepancies are obtained between the deterministic, density independent elasticities of the population growth rate (λ) and the stochastic, density dependent elasticities of the equilibrium population size, extinction probability and invasion exponent. Since the elasticities of λ are often used to guide the management of endangered species, these results are particularly relevant to workers in the field of rare species conservation. While the importance of including environmental variation in the form of stochastic population simulations seems to now be generally accepted, the role of density dependent population regulation is still infrequently considered. Since one of the most common causes of population decline is habitat destruction, leading to an increase in population density within the remaining areas of habitat, this omission may rarely be justified. It is recommended that when elasticity analysis is conducted as part of species conservation efforts, both density dependence and stochasticity are included. Failure to do so may result in the misguided management of endangered species.

Purpose: To document the distribution of macular, retinal nerve fibre layer (RNFL) thickness and optic disc parameters, as measured using optical coherence tomography (OCT) in a population-based sample of young persons and to examine the relationship of these measurements to ocular variables (spherical equivalent refraction [SER] and axial length) and systemic variables (age, gender, anthropometry, ethnicity and birth parameters). Methods: A stratified random cluster sample of 6- and 12-year-old school students from across the Sydney metropolitan region were surveyed and examined using non-contact methods (including biometric measurements with the IOL Master and Canon RK-F1) to determine axial length and SER. The 3rd generation Optical Coherence Tomography instrument (Zeiss Stratus OCT, Dublin, CA, USA) was used to measure macular and RNFL thickness and major optic disc parameters in this sample. Ethnicity and birth parameters were derived using questionnaires. Anthropometric parameters, such as height and weight, were measured using standard methods. Results: The thickness of the foveal, central, inner macular, outer macular and macular volume parameters was normally distributed in both age cohorts. The temporal quadrant was thinner than all other quadrants at both the inner and outer macular regions. The central and inner macula was significantly thicker in boys than in girls, and in Caucasian than in East Asian children. The inner and outer macular regions were slightly, but significantly, thinner with increasing axial length, or myopic refraction. On the other hand, these corresponding regions were significantly thicker with more hyperopic SER. RNFL thickness and RNFLestimated integral were normally distributed in both age groups. RNFL thickness was thinnest for the temporal quadrant, followed by the nasal, inferior, and superior quadrants. RNFL average thickness was marginally greater in boys than in girls and in East Asian than in Caucasian children. The RNFL was thinner with both greater axial length and less hyperopic refractions. Optic disc, optic cup and neural rim parameters were also normally distributed in this young population. In analyses that adjusted for potential confounders, optic disc area increased significantly with axial length and refraction. Neural rim area increased with axial length. There were minimal gender differences in the two age groups. Most optic disc and optic cup dimensions were significantly larger in East Asian than in Caucasian and Middle Eastern children. The foveal minimum and overall RNFL thickness were similar in both age cohorts, while other retinal regions and optic disc size were slightly larger in the 12- than the 6-year-old children. Amblyopic eyes had greater foveal minimum thickness than the normal fellow eye of individual children and the right eyes of non-amblyopic children. Birth weight and head circumference were positively correlated with both RNFL and macular thickness. Conclusions: Macular thickness, RNFL thickness and optic disc parameters were normally distributed in these two age groups of children. Axial length and refraction were important ocular biometric determinants of macular thickness and RNFL thickness. Significant ethnic differences were also demonstrated. RNFL average thickness was also positively associated with optic disc area. Central macular thickness increased in amblyopia. These findings have implications for the interpretation of OCT measurements in research and clinical practice in both children and adult.

Understanding population structure and resource selection are essential for wildlife management and conservation. I assessed the population structure and resource selection of elk (Cervus elaphus) in central Ontario. I used fuzzy and hierarchical cluster analyses to elucidate elk population structure based on spatial data collected from 41 radio-collared elk. I assessed impacts of habitat quality on space use using the minimum convex polygon (MCP) and fixed kernel methods. I evaluated resource selection by elk in winter, spring, summer, and fall, from December 2011 to August 2013, using resource selection functions (RSF’s). I used a generalized linear mixed model (GLMM) to evaluate resource selection functions and used Akaike information criterion (AICc ) to select the best model of 20 candidate models constructed a priori. Models included parameters representing resources known to be important to elk: elevation, aspect, slope, distance to roads and water, and habitat. Both fuzzy and hard clustering indicated that elk in Central Ontario occur in a metapopulation that includes 5 subpopulations. The largest cluster consisted of a core group of 22 radio-collared elk located in Burwash with several satellite subpopulations spread along a 50km long north-south axis and a small subpopulation to the west located in Worthington. Survival rates among subpopulations were similar ranging from 0.71 to 0.83; however, anthropogenic causes of mortality were predominant only in the Burwash subpopulation. Space use and density of elk differed between core and satellite subpopulations. Resource selection by elk differed by time of day and season. In all seasons, elk selected open habitats at night and more forested areas during the day. Elk avoided areas close to roads in spring, but selected them in winter at night. Elk selected higher elevations in winter and for south facing slopes in spring and fall. Elk displayed strong crepuscular activity patterns in all seasons; however, movements were limited in winter. Understanding population structure is important in order to develop appropriate management plans. My results support the conclusion that population structure can be reliably assessed using spatial data. Resource selection is a dynamic process that changes with seasons, as well as animal activity across the diel period. Resource selection should include time of day in order to obtain a complete picture of resources important to a particular species and to support the conservation of habitats used for various animal activities.

Doctor of Philosophy
Department of Entomology
James F. Campbell
Phillip E. Sloderbeck
Robert "Jeff" J. Whitworth
Knowledge of factors influencing the establishment, persistence and distribution of stored-product pests aids the development of effective Integrated Pest Management (IPM) programs in food storage and processing facilities. This research focused primarily on Tribolium castaneum, which is one of the most important pests of mills. Populations of T. castaneum from different food facilities can potentially be interconnected by either their own dispersal behavior or by human transportation. Population genetic structure analyses based on microsatellites and other insertion-deletion polymorphisms (“indels”) showed that populations from different mills around the US are genetically distinct from each other, but the level of differentiation was not correlated with the geographic distance. A potential source of insect infestation within a food facility is spillage that accumulates outside or movement from bulk storage facilities on site. Results from three facilities showed that most stored-product species were captured both inside and outside buildings, but T. castaneum was rarely captured outside of the facilities. Spatial distribution of all species outside was associated with the proximity of buildings, not necessarily with areas with accumulated spillage. T. castaneum populations inside facilities are potentially exposed to frequent genetic bottlenecks resulting from structural fumigations. Changes in allele frequencies through time, based on the analysis of microsatellites and other indels in individuals collected in a mill, confirmed bottleneck effects. To understand how spatial distribution of T. castaneum within a mill could be influenced by environmental and physical factors, a range of variables were measured at each trap location. There was significant variation among trap locations regarding beetle captures and the variables measured, but increase in beetle captures correlated only with increase in temperature and spillage production. Tribolium castaneum response to visual cues could influence attraction to pheromone and kairomone olfactory cues used in traps. Results of laboratory experiments showed that adults respond to tall narrow black shapes and placing traps in front of these shapes can increase captures. This research provides new insights into factors influencing the spatial distribution of T. castaneum and could help in improving monitoring programs for this important pest of the food industry.

Two mesoscale net sampling surveys were conducted in the south-west Atlantic between 34° and 55 °S. The first survey was in the austral spring of 1990 and used both an RMT8 net which was trawled obliquely down to 200 or 300 m and caught mainly macrozooplankton and a Bongo net which was deployed at the surface and sampled mesozooplankton. The second survey was in the austral spring of 1991 and used a Bongo net which was deployed obliquely down to 50 m and sampled mesozooplankton. This thesis considers the species composition and abundance of these samples and represents one of the first insights into the mesoscale biogeography of zooplankton communities in the south-west Atlantic. 155 species from 9 taxonomic groups were considered including euphausiids, hyperiid amphipods, chaetognaths, salps, siphonophores, and nektonic/planktonic fish. Multivariate analyses were used to highlight species assemblage distribution patterns and determine strongly correlated environmental variables. In the 1990 RMT8 samples, species assemblages showed a distribution pattern related to the location of water masses, which was reflected in a combination of water mass and latitude being the most strongly correlated environmental variables. In the 1990 Bongo samples, a combination of seasurface temperature and latitude were most strongly correlated environmental variables and different species assemblages showed a pattern of being located in exclusive temperature ranges. The two sample sets did exhibit some common distribution patterns especially in the warm, sub-tropical waters to the north and the Falkland Shelf to the south. However, there were fundamental differences in the mid-latitudes regions, possibly reflecting the reduced ability of larvae to counteract expatriating forces when compared with adults. Further comparisons made between the 1990 and 1991 Bongo sample sets highlighted some of the causal factors behind distribution patterns. For instance, the precise definition of the boundary between sub-tropical and sub-Antarctic assemblages by the 17.3°C isotherm despite the multitude of expatriating phenomena suggested that many organisms were at the edge of their physiological limits in this region. In polar waters, distribution patterns were consistent but temperatures variable suggesting that advection rather than temperature tolerance was more influential. Further data from Montu (1977) and the Discovery Investigations was examined to add a seasonal dimension to the above patterns as well as providing an insight into the importance of population ecology on community distribution. Studies were concentrated on euphausiid species from which it was apparent that size structure and species dominance changed considerably with season. Estimates of the productivity of these species showed that weight-specific rates were comparable with more sub-tropical regions despite biomass levels being proportionally low. The use of satellite thermal images for predicting faunal distribution patterns was assessed with respect to future biogeographic analysis of this region. Images were a good predictor at the sub-tropical boundary but a poor predictor in other regions highlighting the fact that in situ net sampling methods still appear to be the most effective and reliable investigative tools for biogeographic analysis.

Bibliography: leaves 182-196.
The thesis first reviews the research on zooplankton ecology in the Benguela system and then evaluates the contribution of euphausiids to the zooplankton biomass of the southern Benguela region. The study further investigates the population dynamics and maintenance of the dominant euphausiid, Euphausia lucens, principally in the St Helena Bay region because of its importance as a recruitment area for the pelagic fishery.