Stochastic compartment models are widely used in modeling processes for biological populations. The residence time has been especially useful in describing the system dynamics in the models. The direct calculation of the distribution for the residence time of stochastic multi-compartment models is very complicated even with a relatively simple model and often impossible to calculate directly. This dissertation presents an analytical method to obtain the moment generating function for stochastic multi-compartment models and describe the distribution of the residence times, especially systems with nonexponential lifetime distributions. A common method for obtaining moments of the residence time is using the coefficient matrix, however it has a limitation in obtaining high order moments and moments for combined compartments in a system. In this dissertation, we first derive the bivariate moment generating function of the residence time distribution for stochastic two-compartment models with general lifetimes. It provides any order of moments and also enables us to approximate the density of the residence time using the saddlepoint approximation. The approximation method is applied to various situations including the approximation of the bivariate distribution of residence times in two-compartment models or approximations based on the truncated moment generating function. Special attention is given to the distribution of the residence time for multi-compartment semi-Markov models. The cofactor rule and the analytic approach to the two-compartment model facilitate the derivation of the moment generating function. The properties from the embedded Markov chain are also used to extend the application of the approach. This approach provides a complete specification of the residence time distribution based on the moment generating function and thus provides an easier calculation of high-order moments than the approach using the coefficient matrix. Applications to drug kinetics demonstrate the simplicity and usefulness of this approach.

This study explores the relationship between living arrangement and psychological wellbeing in retired elderly individuals living in Yancheng, Jiangsu (PR China). Data on mode of residence, socio-economic background, daily activities, and intergenerational dynamics were collected from 200 subjects, and their potential correlations with depression (assessed via the Geriatric Depression Scale Short Version) were analyzed. Univariate as well as logistic regression confirmed mode of residence as a significant predictor of depression in this group. The following depression odds ratios associated with each mode of residence were derived via logistic regression: 1) nuclear household, i.e. living with a spouse only ¨C 1 [reference category], 2) multigenerational households in which a spouse is not present ¨C 4.341, 3) multigenerational households in which a spouse is present ¨C 0.781, and 4) living alone ¨C 3.018. Based on these ratios, we conclude that the traditional model of intergenerational coresidence is not, in itself, associated with less depression. Rather, it is the presence of a sharing spousal in a household (whether single or multigenerational) that protects against elderly depression. Other predictors of depression identified in backward logistic regression included presence of a chronic illness and self assessed wealth status. Additionally, a number of psychosocial variables were identified as independently correlated with depression, but were subsequently selected out by multivariate analysis. These included: educational background, religious affiliation, membership in an organization, attitude toward aging, and family status. Based on this study, we believe that efforts to promote mental wellbeing among today¡¯s Chinese elders should be directed toward psychosocial factors that are modifiable (education, building supportive social networks etc.) rather than insisting on the traditional ideal of multigenerational living and dependence on filial piety.

Studiens syfte var att undersöka hur socialsekreterare tolkar begreppet uppehållsrätt när EU-medborgare ansöker om försörjningsstöd. Intersektionellt perspektiv användes för att belysa maktförhållanden mellan socialsekreterare som representatner för svenska myndigheter och klienter med utländsk härkomst. I studien användes domar från svenska förvaltningsrätter som analyserades med kvalitativ diskursanalys. Resultat kategoriserades in i kategorier som rörde socialsekreteres tolkningar av uppehållsrätten, omständigheter avgörande för bedömning av uppehållsrätten och socialsekreterares tolkningar av EU-medborgares rätt till försörjningsstöd. Data om EU-medborgares medborgarskap och kön samlades in för att undersöka deras eventuella påverkan på utfall av ansökan om försörjningsstöd. Analys av resultat visade signifikant inkonsekvens i såväl socialsekreterares tolkningar av uppehållsrätten som i tillämpning av relevanta lagar. EU-medborgares rättigheter till försörjningsstöd nekades på grund av att EU-medborgare bedömdes vara "ekonomiskt icke aktiva personer" eller inte ansågs ha "en verklig möjlighet till att få anställning". Varken EU-medborgares medborgarskap eller kön kunde kopplas till utfall av deras ansökan om försörjningsstöd. / The purpose of this study was to examine how social workers interpret right of residence when EU-citizens apply for social assistance by claiming their residential rights. The intersectional perspective was used as a theoretical approach in order to illustrate power relationship between social workers as representatives for Swedish authorities and clients of foreign origin. Using appeal documents from Swedish administrative courts as a study material and a qualitative discourse analysis as a data collection method the results were classified into categories concerning social workers’ interpretations of right of residence, circumstances considered by social workers as crucial for right of residence and social workers interpretations of EU-citizens’ entitlement to social assistance. Data regarding EU-citizens’ nationalities and gender were collected in order to identify their possible influence on outcome of their applications. Analysis of results identified a significant inconsistency in social workers’ interpretations of right of residence as well as in application of the law. EU-citizens’ entitlement to social assistance was denied on terms of EU-citizens being “economically inactive persons” or not having “a real chance to get an employment”. Neither EU-citizens nationalities nor gender could be linked to outcomes of their applications for social assistance.

Growth and development over the past one hundred years has resulted in the construction of causeways and navigational channels in Tampa Bay. Urbanization has lead to bathymetric alterations of the bay, and thus has effectively changed the residual salinity, flow fields, and transport time in Tampa Bay. In this study a numerical ocean model of Tampa Bay was first used to simulate the circulation for 2001-2003 using present day bathymetry. Then, an identical simulation was performed using the bathymetry generated from 1879 depth soundings. The residual (30-day time average) circulation fields and salinity, along with transport times was intercompared for different freshwater inflow conditions to investigate the impacts of these physical alteration. The salinity for the "present" simulation is about 3 psu higher than the "1879" simulation in the areas of upper Middle Tampa Bay, Lower Hillsborough Bay and Old Tampa Bay, a result of a stronger axial pressure gradient associated with the deeper more extensive channels. Velocities are up to 10 cm/s higher in the "present" run than in the "1879" simulation in the areas where water must converge and diverge through the narrow openings of the bridges/causeways. Transport time is short (~10 days) during strong residual circulation, and long (~90 days) during weak residual circulation. Bridges and causeways are associated with longer transport times (~90 days), except in the area North of the Courtney Campbell Causeway. The navigational channel is associated with long transport times during dry periods and short transport time during wet periods.

Natural gas is an important transitional energy source to replace more carbon intensive coal combustion in the face of climate change and increasing global energy demands. A significant proportion of natural gas reserves (~20%) were recently generated by microorganisms that degrade organic-rich formations (i.e. coal, shale, oil) in-situ to produce methane. Recent studies have shown that these microbial communities may be potentially stimulated to generate more methane to extend the lifetime (~10 years) of existing biogenic gas wells. This dissertation investigates how microbial coalbed methane (CBM) systems are impacted by geochemical conditions, microbial community composition, and groundwater recharge. The first study is a review and synthesis of existing basic research and commercial activities on enhancement of microbial CBM generation, and identification of key knowledge gaps that need to be addressed to advance stimulation efforts. The second study couples water and gas geochemistry with characterization of microbial communities in coalbeds in the Powder River Basin (PRB), Wyoming to investigate the influence of microbiology on water and gas geochemistry. Geochemistry results indicated that nutrients are likely source in situ from coal, and that all sulfate must be removed from the system before methanogenesis will commence. Increased archaeal (i.e. methanogens) diversity was observed with decreasing sulfate concentration, while sulfate reducing bacterial communities were different in wells with high sulfate concentrations (sulfate reducing conditions) when compared to wells with low sulfate concentrations (methanogenic conditions). The third study uses noble gases to constrain the residence time of groundwater associated with CBM in the PRB. Measured diffusional release rates of 4He from PRB coals were ~800 times greater than typical rates observed in sandstone or carbonate aquifers, and measured 4He values far exceeded expected values from in-situ decay of U and Th. Groundwater 4He residence times ranged from <1 to ~800 years using the measured diffusion rates versus ~130 to 190,000 years using a standard model. Coal waters with the longest residence time had the highest alkalinity concentrations, suggesting greater extents of microbial methanogenesis, although there was no relationship between groundwater "age" and methane concentrations or isotopic indicators of methanogenesis. Constraining the relationship between microbial activity (e.g. mechanisms of coal biodegradation and methane generation), environmental geochemical conditions, and groundwater flow is important to better understand subsurface hydrobiogeochemical processes and to ensure the success of future projects related to stimulation of microbial CBM.

This work explores the hydraulic performance of a wastewater lagoon system located in San Antonio, Bolivia. The system consists of one facultative pond and two maturation ponds in series and is managed through a locally elected water committee. A tracer study was performed on the primary facultative pond and an analysis of the solids accumulation on the bottom of the facultative lagoon was also performed. The results were used to generate residence time distribution curves and provide an estimate of mean residence time in the system. The data was used to examine hydraulic efficiency as it relates to short-circuiting and dead zones. A sludge study accumulation study was performed using the white towel method and the resulting measurements were interpolated to determine a total estimated sludge volume of 169 m3 (which is 8% of the facultative pond volume). An orange study was also performed to assess the surface flow pattern in the system. The results were compared with a computational 2-d model. The 2-d model incorporated the estimated sludge distribution and provided a good fit for the tracer dye concentrations measured in the field over the 12 day study period. Simple models such as the Tanks in Series and the Completely mixed model were evaluated and abandoned because of their inability to model the physical behavior in the system. The Completely mixed model did however perform better than the Plug flow model. After comparing the tracer results from the reactor models that were considered: Tanks in Series, Completely mixed fluid, manual interpolation and the results from the 2-d cfd flow simulation, the results that provided the best fit for the data over 12 days was the manual interpolation method at a flow rate of 98 m3/day and configuration D at 60 m3/day. However, because of uncertainty as to what depth to obtain a representative area for the 2-d simplification and sensitivity to flow; all four configurations were considered for estimating the MHRT at the lowest measured flow rate of 60 m3/day. The results at a flow rate of 60 m3/day varied between 10.88 and 13.04 days for the MHRT with a hydraulic efficiency that varied between 33-51.6% (accounting for sludge volume). This is much shorter than the actual nominal retention time of 37 days and the design nominal retention time of 26 days. As a result it was concluded that short-circuiting was occurring in the facultative lagoon.

Šiandien vaikas turi visas universalių žmogaus teisių dokumentų nuostatose įtvirtintas teises kaip suaugęs asmuo, tačiau to nepakanka. Nors vaikas yra kiekvienos visuomenės pagrindas bei ateitis, tačiau kartu jis yra kiekvienos visuomenės silpnoji dalis, priklausoma nuo aplinkos, dažniausiai nesugebanti apginti savo interesų, jo teises galima įgyvendinti tik per kitų asmenų – visų pirma, tėvų, teises ir pareigas. Tačiau daugeliu atvejų vaikų teisių ir teisėtų interesų pažeidimams atsirasti sąlygas sudaro būtent suaugusiųjų asmenų, tarpusavyje nesutariančių tėvų konfliktai. Vaikų, atsidūrusių tėvų konfliktų centre, padėtis yra reikalinga apmąstymų. Oficiali civilinių bylų statistika patvirtina, jog šiandien ginčų dėl vaikų gyvenamosios vietos nustatymo sprendimas teismine tvarka itin aktualus. Šių ginčų gausa įpareigoja valstybę bei visuomenę nebūti abejingais, kadangi adekvatus šių ginčų teisinis reglamentavimas gali kokybiškai užtikrinti vaiko teisių apsaugą. Darbe siekiama įvertinti, kaip įgyvendinami geriausi vaiko interesai sprendžiant ginčus dėl vaikų gyvenamosios vietos nustatymo, siekiama atskleisti šių ginčų probleminius aspektus, pasiūlyti galimus jų sprendimo būdus. Aptariamas teismo vaidmuo šio pobūdžio ginčuose, valstybinės vaiko teisių apsaugos institucijos dalyvavimas, siekiama įvertinti šių institucijų dalyvavimą geriausių vaiko interesų požiūriu. Analizuojamas pagrindinių principų, kuriais vadovaujantis sprendžiami ginčai dėl vaiko gyvenamosios vietos... [toliau žr. visą tekstą] / Today a child is entitled with the same rights enshrined in the provisions of the universal human rights documents as an adult, but it is not enough. Though the child is the foundation and the future of each society, at the same time it is the weakest part of every society, dependent on the environment, often unable to defend its interests; its rights can only be realized through the other personsʼ, in particular, parental rights and responsibilities. However, in many cases, the conditions for infringement of the childrenʼs rights and legitimate interests occur due to the conflicts arising between the adults, arguing parents. The situation of children, who find themselves in the centre of conflict of their parents, is to be considered properly. The official statistics of the civil cases proves that today the question of judicial judgment of the disputes on establishment of the residence place of the child is of particular interest. Multiplicity of such disputes obligates the state and society not to be indifferent, because the adequate legal regulation of these disputes can ensure the quality of protection of the childrenʼs rights. Masterʼs thesis aims to access realization of the best interests of the child in resolution of disputes regarding establishment of the residence place of the child, to determine the problematic aspects of these disputes, to offer possible solutions. Masterʼs thesis discusses the role of the court in such disputes, participation of the state child... [to full text]

Background: The prevalence of overweight and obesity in Canadian youth has increased considerably over the past few decades. In spite of considerable efforts, individual-level behavioural modification strategies have not been successful at preventing and treating obesity in youth. Research is emerging that has shifted attention to the environmental-level determinants of obesity. There is some evidence that the number and types of food retailers in a given neighbourhood may impact obesity risk in the individuals living in that neighbourhood, but little is known about the impact of the food retail environment on Canadian youth. Objectives: 1) To describe the food environment surrounding the school neighbourhoods of Canadian youth (grades 6 to 10), and, determine whether access to food retailers around schools differs by area-level SES. 2) To determine whether the number and type of food retailers surrounding schools is related to the overweight status of the students attending those schools. Each of these objectives was explored in a separate manuscript. Methods: A trend test was performed to determine if exposure to food retailers varied by neighbourhood socioeconomic status (SES) for 188 schools across Canada. Logistic regression was performed using a multilevel modeling approach to determine if an association existed between exposure to food retailers and overweight and obesity in the 7,281 school-aged youth attending the 188 schools, adjusting for individual- and area-level covariates. Types of food retailers considered included: full-service restaurants, fast food restaurants, sub/sandwich shops, donut/coffee shops, convenience stores, and grocery stores. Results: Objective 1. Nearly 75% of schools had at least one food retailer within 1 km of schools, and over 90% had at least one food retailer within 5 km. Exposure to the different types of food retailers within 1 km of schools did not vary significantly (p<0.05) across schools in low, moderate, and high SES neighbourhoods, with the exception of full-service restaurants. At the 5 km distance, the SES gradient was significant across all food retailer types, with low SES neighbourhoods exposed to the least number of food retailers. This effect disappeared when population density (number of retailers per 10,000 people) was considered, except for sub/sandwich shops and donut/coffee shops. Objective 2. Increased exposure to all six types of food retailers in the neighbourhoods surrounding schools was associated with a decreased likelihood of overweight and obesity. At the 1 km distance, the total number of food retailers had the strongest protective effect, while individual types of food retailers had a stronger effect at the 5 km distance. Conclusions: Objective 1. Most students in Canada have at least one food retailer within walking distance of their school. The food retail environment surrounding schools is not significantly impacted by the neighbourhood SES. Objective 2. Increased exposure to different types of food retailers in school neighbourhoods is associated with a decreased likelihood of overweight and obesity in Canadian youth. This suggests that having access to a large number and variety of food choices may facilitate healthy food choices and protect against the development of overweight and obesity. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2007-09-26 10:25:11.453

This study is a qualitative inquiry into the lives of first-year residence students at the Durban University of Technology. Six students volunteered to be participants in this study, and they discussed their life stories freely and frankly. Interviews were conducted as conversations rather than formal question-and-answer sessions, and this method elicited rich and vibrant material. This dissertation considers the specific stories of two of these students, Student A and Student B, and how their life experiences have affected them. The study looks at what these experiences have been whilst the students were at home and at school; what their experiences are as first-year students residing in an institutional residence; and how all these experiences have impacted on their transition to life at university. The theory of development and the search for identity are at the core of this investigation. Their life stories have illustrated the role that development plays in their individual growth and development through the adolescent and young adult years. Their search for their own identity as African youth in post-apartheid South Africa has direct relevance and bearing on the reality of life in the country today. The students identify issues that cause them difficulty and concerns, such as family relationships, homesickness, cultural conflicts, and peer pressure. They talk at length about specific incidents and situations that have caused them stress and worry, and through their stories we can see how they are developing their own identity as they try to make sense of their world at home, at university, and in residence. The conclusion highlights the themes that have risen through the analysis of their stories: the commonalities, the pressures, the worries and concerns, and the interventions that could be made to ease the transition phase. / Thesis (M.Ed.)-University of KwaZulu-Natal, 2007.

This thesis examines how the non-Newtonian characteristics of liquid hog manure affect the flow conditions within a steady-flow anaerobic digester. There are three main parts to this thesis. In the first part of this thesis, the physical properties of liquid hog manure and their variation with temperature and solids concentration are experimentally determined. Naturally¬¬-settled manure sampled from an outdoor storage lagoon is studied, and density, viscosity, and particle size distribution are measured. Hog manure with total solids concentrations of less than 3.6% exhibits Newtonian behaviour; manure between 3.6% and 6.5% total solids is pseudoplastic, and fits the power law; manure with more than 6.5% total solids exhibits non-Newtonian and time-dependent characteristics. The second part of this thesis investigates the flow of Newtonian and non-Newtonian fluids—represented by tap water and xanthan gum solution, respectively—within four lab-scale reactor geometries, using residence time distribution (RTD) experiments. The effect of reactor geometry, flow rate, and fluid viscosity are evaluated. In the third part of this thesis, flow conditions within lab-scale and pilot-scale anaerobic digester reactors are simulated using three-dimensional modeling techniques. The RTDs of lab-scale reactors as predicted by the 3D numerical models compare well to the experimental results. The 3D models are also validated using data from particle image velocimetry (PIV) experiments. Finally, the viscous properties of liquid hog manure at 3% and 8% total solids are incorporated into the models, and the results are evaluated.