Thesis (Ph. D.)--University of Michigan, 1943. / Includes bibliographical references (leaves 184-198).

Thesis (M.S.)--University of North Carolina at Wilmington, 2005. / Includes bibliographical references (leaves: [70]-74)

Karenia brevis dinoflagellate blooms off the west coast of Florida can create devastating effects on marine communities when they release a neurotoxin known as a brevetoxin. These blooms, informally referred to as red tides, can cause massive fish kills, necessitate closures of shellfish fisheries, and can even leave lingering toxins that impact shelf communities long after the bloom has dissipated. As a result, much effort has been put into studying K. brevis bloom initiation and dynamics. However, how K. brevis blooms impact Florida's fisheries is not fully understood because the relationship between K. brevis cell counts and fish mortality is poorly described. To study this relationship and the ecosystem response to K. brevis blooms, Ecopath with Ecosim (EwE) modeling is used to force K. brevis bloom mortality on the shelf ecosystems by using a recently developed time series that indexes K. brevis bloom severity. This index dynamically drives K. brevis bloom mortality in EwE in a historical reconstruction scenario from 1980 to 2009. Three hypotheses on ecosystem response are explored using Gag grouper as a case study. We postulate a) that K. brevis blooms impose bottom-up and top-down effects on the food web, b) that episodic perturbations by these blooms shape the community structure and c) that fishing pressure exacerbates those effects. Results support the hypothesis that K. brevis blooms pose top-down food web pressures, which is seen by evidence of trophic cascading. Changes in community structure with bloom mortality are also evidenced by changes seen in biodiversity and richness. An exacerbation of those effects as a result of heavy fishing pressure is evident, however, is only seen during severe bloom events. Little to no changes were found in the mortality from K.brevis blooms during blooms of average severity, and less mortality was imposed on the system during blooms of particularly low severity. However, this may be an artefact of the mode of action of K. brevis in EwE. Investigation of bloom effects on Gag showed that natural mortality rates of Gag appear to be largely influenced by mortality incurred during K. brevis blooms relative to the low rate of predation on Gag. Moreover, consumption rates of Gag on its prey were found to increase under a realistic schedule of these blooms. This may be due to a combination of effects, including increased mortality on competitors (making more prey available for Gag) and a lowering of the mean age of the Gag stock, which increases population productivity.

A fish kill was observed in a historically freshwater region of the Everglades, coinciding with a spike in salinity. Sea level rise and altered hydrology allow freshwater wetland systems to be susceptible to saltwater intrusion. Most wetlands are characterized by highly organic soils with microbial communities starved of oxygen, seeking alternative electron acceptors. Seawater contains sulfate (SO42-), which is one of the alternative electron acceptors. Provided with sufficient quantities, sulfate-reducing bacteria (SRB) outcompete other anaerobes and produce toxic hydrogen sulfide. This study asked, what combination of soil organic matter (SOM) and SO42- are needed to produce sulfide concentrations potentially lethal to freshwater fish? Soil samples were collected from two freshwater wetlands with varying SOM content and incubated in microcosms at four SO42- concentrations (0, 0.75, 4.0, and 12.0 mM Na2SO4). Sulfide concentrations produced were compared to published data on lethal sulfide toxicity levels for aquatic life. This study demonstrated that high SOM soils (89.3 ± 0.2 % moisture) incubated with SO42- concentrations > 0.75 mM, rapidly produced toxic sulfide concentrations (> 5 ppm S2-) within 24 hrs.. While many freshwater species may tolerate a salinity of 1 ppt (0.75 mM SO42-), this SO42-concentration is sufficient to support SRB and lead to toxic sulfide production. ese results support the need to restore freshwater hydrology in wetland systems, such as the Everglades, thereby protecting against the rapid ecological effects of saltwater intrusion.

This collection of two short stories and one novella seeks to express and embody concepts of narrative form and technique developed over the course of this graduate program with regards to the formulation of believable, nonrealist fictional realities in an American idiom which can enter into the global critical conversation of similarly-purposed international literature.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-03-02T12:35:33Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_JRMGR (2).pdf: 5709787 bytes, checksum: 202e0d4b953f954e36da5e22b1d9c53d (MD5) / Made available in DSpace on 2017-03-02T12:35:33Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_JRMGR (2).pdf: 5709787 bytes, checksum: 202e0d4b953f954e36da5e22b1d9c53d (MD5) Previous issue date: 2016-01-15 / Nowadays the computational thinking is one of the most important skills a person should develop to be more well prepared for the near future. By the middle of this century, this ability will probably have the same level of importance of fundamental skills like reading and writing, and people will need to learn programming and problem solving with computational thinking from an early age. Studies are trying to stimulate the introduction of this skill set to young children, and this has been done since 1967 when the Massachusetts Institute of Technology created the first language aiming this kind of public called LOGO. Although the studies in the area of developing computational thinking on children started almost six decades ago, the importance of teaching programming in schools is not widely spread, in places like Brazil, this skill is starting to be introduced to children older than 10 yearsold. In contrast, the United States and some european countries are using a variable set of approaches to introduce these concepts to young children varying from 4 to 12 years old, usually by creating toys and games which these concepts can be developed within them. Unfortunately most of approaches are aimed for already literate children, very few of them do not require reading skills, limiting the minimum age of users to approximately 6 years old. This work has the intention to argue that toddlers are not only able to develop algorithms and initiate the development of computational thinking skills, but also this practice will be quite profitable for their future. A survey involving 9 children with between 4 and 6 years old is presented, where the selected children played a game developed specially for this work, and their performance was able to produce data that is going to be analyzed further to test the main hypothesis which is " Toddlers can develop algorithmic thinking by playing programming games ", additionally, while reviewing the literature, problems related to the effects of letting children use smart devices and internet without supervision were identified, in order to advocate the usage of this technology by young children, possible causes and risks of these problems are presented and ways to avoid them as well, the results of this work are encouraging, all toddlers involved were able to play the game developed. / Nos dias de hoje o pensamento computacional é uma das habilidades mais importantes que uma pessoa deve desenvolver para se preparar melhor pro futuro próximo. Em poucos anos essa habilidade será tão importante como ler e escrever, pessoas precisarão aprender a programar e resolver problemas com pensamento computacional desde cedo. Estudos que tentam estimular a introdução dessas habilidades para crianças são feitos desde 1967 quando o Institudo de Tecnologia de Massachusetts criou a primeira linguagem para esse público chamada LOGO. Embora os estudos na area de desenvolvimento do pensamento computacional em crianças tenha começado a mais de seis décadas atrás, a importância de ensinar programação em escolas não é amplamente difundida, em lugares como Brasil, essa habilidade está começando a ser introduzida a crianças com mais de 10 anos de idade. Por outro lado, nos Estados Unidos e em alguns países europeus diversas abordagens vem sendo usadas para introduzir esses conceitos para crianças de 4 a 12 anos de idade, normalmente são criados brinquedos e jogos que podem ajudar a desenvolver tais conceitos. Infelizmente a maioria dessas abordagens são focadas em crianças alfabetizadas, poucas não requerem a habilidade de leitura, limitando a idade mínima a 6 anos de idade. Esse trabalho argumenta que crianças muito novas não somente são capazes de desenvolver algoritimos e iniciar o desenvolvimento de habilidades do pensamento computacional, como essa prática será bastante proveitosa para o futuro deles. É apresentada uma pesquisa envolvendo 9 crianças com idade entre 4 e 6 anos, onde as crianças selecionadas jogam um jogo desenvolvido especialmente para este trabalho, e a performance deles foi capaz de produzir dados que foram analisados para testar a hipótese principal que é " Crianças muito novas podem desenvolver pensamento algoritimico jogando jogos de programação ", adicionalmente, enquanto a literatura foi revisada, problemas relacionados aos efeitos de permitir crianças a usar dispositivos móveis e internet sem a supervisão dos responsáveis foram identificados, para defender o uso desse tipo de tecnologia na educação de crianças as possíveis causas e meios de evitar esses problemas foram levantados, os resultados desse trabalho são encorajadores, todas as crianças envolvidas foram aptas a jogar o jogo desenvolvido com uma boa performance.

A expansão das atividades humanas está associada a várias ameaças antrópicas que afetam a biodiversidade tropical, especialmente a perda e fragmentação de habitat, o continuado crescimento populacional humano e a expansão de infraestrutura, como estradas e rodovias. Embora seja esperado que as ameaças antrópicas interajam e criem mosaicos de manchas de habitat de diferentes qualidades, há ainda poucos estudos sobre os efeitos aditivos e interativos de diferentes ameaças sobre a biodiversidade ou sobre a capacidade de espécies nativas de usar remanescentes de diferentes qualidades. De fato, a maioria dos estudos focaram em apenas uma ou poucas ameaças isoladas, na escala do fragmento em vez da escala da paisagem e não consideraram as variações na qualidade dos remanescentes. Mamíferos de maior porte são um bom modelo de estudo porque possuem um conjunto de características que os tornam particularmente vulneráveis a várias ameaças antrópicas. Dada a dificuldade de obter dados sobre estas espécies elusivas em escalas espaciais adequadas, entrevistas com moradores locais vêm sendo cada vez mais usadas para acessar a distribuição de mamíferos de maior porte, e podem fornecer informações confiáveis. Através da estimativa da ocorrência de 15 espécies de mamíferos de maior porte por meio de entrevistas com o chefe de 12 unidades domésticas em cada uma de 20 paisagens em uma região de pós-fronteira de 1 milhão ha na Amazônia, investigamos: (i) que tipo de habitat e em qual escala espacial está associado com a ocorrência das espécies, e (ii) os efeitos, a importância relativa e as interações de quatro ameaças antrópicas - cobertura de habitat, fragmentação de habitat, densidade populacional humana e densidade de estrada - sobre a persistência das espécies. Dados de presença/ausência nos arredores de 227 unidades domésticas foram analisados usando modelos lineares generalizados mistos e seleção de modelos baseada no Critério de Informação de Akaike em duas etapas. A persistência das espécies maiores e ameaçadas não foi necessariamente afetada pela qualidade do habitat, mas elas responderam majoritariamente a cobertura de habitat em escalas maiores. A chance de persistência de todas as espécies - mesmo das duas menores, que não responderam à perda de habitat isoladamente - foi afetada por alguma combinação das quatro ameaças antrópicas. Efeitos aditivos entre as ameaças antrópicas foram mais importantes do que as interações entre elas na determinação da ocorrência de mamíferos de maior porte. Enquanto os efeitos da perda de habitat foram mais fortes do que os efeitos da fragmentação de habitat per se, a densidade de estradas foi tão importante quanto à perda de habitat para a ocorrência das espécies. Por último, não houve um padrão claro em termos do grau de ameaça e do tamanho corpóreo por trás da reposta dos mamíferos de maior porte a ameaças antrópicas combinadas. Nosso estudo sugere que áreas protegidas em terras públicas ou privadas na Amazônia devem ser grandes para assegurar a persistência de mamíferos de maior porte, mas podem incluir mosaicos de florestas primárias e secundárias. Os resultados também ressaltam a necessidade de considerar os impactos acumulados de múltiplas ameaças simultaneamente - em especial, as consequências da expansão da malha viária - em planejamentos e manejos, de maneira a evitar subestimar a chance de extinções. Evitar que paisagens na Amazônia se tornem muito desmatadas e alteradas é fundamental, dado que a persistência até mesmo das espécies mais comuns pode ser prejudicada, afetando um dos serviços ecossistêmicos mais importantes para moradores locais - a carne de caça - e potencialmente erodindo o valor que estes atribuem às florestas / The expansion of human activities is associated to a myriad of anthropogenic threats that affect tropical biodiversity, especially habitat loss and fragmentation, the continued human population growth and the expansion of infrastructure, as roads and highways. Although anthropogenic threats are expected to interact and to create mosaics of patches of varying quality, their additive and interaction effects on biodiversity, as well as the extent native species are able to use remnants of distinct quality, have yet been poorly studied. Indeed most studies focused on only one or few threats in isolation, on the patch rather than the landscape scale and did not considered the varying quality of remnants. Large mammals are a good study model as they have a set of traits that make them particularly vulnerable to several anthropogenic threats. Due to the difficulties in gathering data on these elusive species at adequate spatial scales, interviews with local residents have increasingly being used to access their distribution and can provide reliable information. By estimating the occurrence of 15 large mammal species through interviews with the head of 12 households within each of 20 landscapes across a 1-million ha post-frontier region in Amazonia, we investigated: (i) which habitat type at which spatial scale is associated with species occurrence, and (ii) the effects, relative importance and interactions of four anthropogenic threats - habitat cover, habitat fragmentation, human population density and road density - on species persistence. Presence/absence data across the surroundings of 227 households was analyzed using generalized linear mixed-effects models, and a two-step model selection based on Akaike’s Information Criteria. The persistence of larger and endangered species was not necessarily affected by habitat quality, but they responded to habitat cover mostly at larger spatial scales. The chance of persistence of all species - even the two smallest that were not affected by habitat loss alone - was disrupted by some combination of the four anthropogenic threats. Additive effects between anthropogenic threats were more important than their interaction in determining the occurrence of large mammals. While the effects of habitat loss were stronger than the effects of habitat fragmentation per se, road density was as important as habitat loss to species occurrence. Finally, there was no clear pattern in threat status or body size underlying the response of large mammals to combined anthropogenic threats. Our study suggest that protected areas in public or private lands in Amazonia should be large to secure the persistence of large mammals, but may include mosaics of primary and secondary forest. The findings also highlight the need to take into account the accumulated impacts of multiple threats simultaneously - particularly, the consequences of the expansion of the road network - in planning and management, as a way to avoid underestimating the chance of extinctions. Preventing Amazonian landscapes to become heavily deforested and altered is critical, as the persistence of even common species can be impaired, affecting one of the most important ecosystem services provided to local residents - bushmeat - and potentially eroding the value people attribute to forests

Upon consultation with NPS faculty, the School has determined that this thesis may be released to the public, its distribution is unlimited effective August 25, 2011. / One result of the break-up of the Soviet Union is that the DOD has been forced to reevaluate the roles of each of the Armed Services based on the declining resource pool. From the Marine Corps' evaluation of itself came the Combined Arms Regiment (CAR) concept. The objective of this study was to develop an estimate of the Life Cycle Cost (LCC) of the two possible vehicles used with the CAR and the CAR's components. Standard cost factors are used to cost out the various organizations involved. Two supporting analyses done in this study are: an evaluation of the Marine Corps' role in national security and how the CAR could be used to support that security role, and a comparison of the vehicle option operating characteristics which was done to enrich the dimensions under which the CAR could be evaluated. The results of the study are a tool which can help Marine Corps planners make more informed decisions in regards to the CAR concept. The final conclusion, based on the assumption that any CAR would act as a follow-on element of the MAGTF, was that although the CAR(LAV) was a workable option, the CAR using upgraded AAVs was the better, more cost effective option.

A expansão das atividades humanas está associada a várias ameaças antrópicas que afetam a biodiversidade tropical, especialmente a perda e fragmentação de habitat, o continuado crescimento populacional humano e a expansão de infraestrutura, como estradas e rodovias. Embora seja esperado que as ameaças antrópicas interajam e criem mosaicos de manchas de habitat de diferentes qualidades, há ainda poucos estudos sobre os efeitos aditivos e interativos de diferentes ameaças sobre a biodiversidade ou sobre a capacidade de espécies nativas de usar remanescentes de diferentes qualidades. De fato, a maioria dos estudos focaram em apenas uma ou poucas ameaças isoladas, na escala do fragmento em vez da escala da paisagem e não consideraram as variações na qualidade dos remanescentes. Mamíferos de maior porte são um bom modelo de estudo porque possuem um conjunto de características que os tornam particularmente vulneráveis a várias ameaças antrópicas. Dada a dificuldade de obter dados sobre estas espécies elusivas em escalas espaciais adequadas, entrevistas com moradores locais vêm sendo cada vez mais usadas para acessar a distribuição de mamíferos de maior porte, e podem fornecer informações confiáveis. Através da estimativa da ocorrência de 15 espécies de mamíferos de maior porte por meio de entrevistas com o chefe de 12 unidades domésticas em cada uma de 20 paisagens em uma região de pós-fronteira de 1 milhão ha na Amazônia, investigamos: (i) que tipo de habitat e em qual escala espacial está associado com a ocorrência das espécies, e (ii) os efeitos, a importância relativa e as interações de quatro ameaças antrópicas - cobertura de habitat, fragmentação de habitat, densidade populacional humana e densidade de estrada - sobre a persistência das espécies. Dados de presença/ausência nos arredores de 227 unidades domésticas foram analisados usando modelos lineares generalizados mistos e seleção de modelos baseada no Critério de Informação de Akaike em duas etapas. A persistência das espécies maiores e ameaçadas não foi necessariamente afetada pela qualidade do habitat, mas elas responderam majoritariamente a cobertura de habitat em escalas maiores. A chance de persistência de todas as espécies - mesmo das duas menores, que não responderam à perda de habitat isoladamente - foi afetada por alguma combinação das quatro ameaças antrópicas. Efeitos aditivos entre as ameaças antrópicas foram mais importantes do que as interações entre elas na determinação da ocorrência de mamíferos de maior porte. Enquanto os efeitos da perda de habitat foram mais fortes do que os efeitos da fragmentação de habitat per se, a densidade de estradas foi tão importante quanto à perda de habitat para a ocorrência das espécies. Por último, não houve um padrão claro em termos do grau de ameaça e do tamanho corpóreo por trás da reposta dos mamíferos de maior porte a ameaças antrópicas combinadas. Nosso estudo sugere que áreas protegidas em terras públicas ou privadas na Amazônia devem ser grandes para assegurar a persistência de mamíferos de maior porte, mas podem incluir mosaicos de florestas primárias e secundárias. Os resultados também ressaltam a necessidade de considerar os impactos acumulados de múltiplas ameaças simultaneamente - em especial, as consequências da expansão da malha viária - em planejamentos e manejos, de maneira a evitar subestimar a chance de extinções. Evitar que paisagens na Amazônia se tornem muito desmatadas e alteradas é fundamental, dado que a persistência até mesmo das espécies mais comuns pode ser prejudicada, afetando um dos serviços ecossistêmicos mais importantes para moradores locais - a carne de caça - e potencialmente erodindo o valor que estes atribuem às florestas / The expansion of human activities is associated to a myriad of anthropogenic threats that affect tropical biodiversity, especially habitat loss and fragmentation, the continued human population growth and the expansion of infrastructure, as roads and highways. Although anthropogenic threats are expected to interact and to create mosaics of patches of varying quality, their additive and interaction effects on biodiversity, as well as the extent native species are able to use remnants of distinct quality, have yet been poorly studied. Indeed most studies focused on only one or few threats in isolation, on the patch rather than the landscape scale and did not considered the varying quality of remnants. Large mammals are a good study model as they have a set of traits that make them particularly vulnerable to several anthropogenic threats. Due to the difficulties in gathering data on these elusive species at adequate spatial scales, interviews with local residents have increasingly being used to access their distribution and can provide reliable information. By estimating the occurrence of 15 large mammal species through interviews with the head of 12 households within each of 20 landscapes across a 1-million ha post-frontier region in Amazonia, we investigated: (i) which habitat type at which spatial scale is associated with species occurrence, and (ii) the effects, relative importance and interactions of four anthropogenic threats - habitat cover, habitat fragmentation, human population density and road density - on species persistence. Presence/absence data across the surroundings of 227 households was analyzed using generalized linear mixed-effects models, and a two-step model selection based on Akaike’s Information Criteria. The persistence of larger and endangered species was not necessarily affected by habitat quality, but they responded to habitat cover mostly at larger spatial scales. The chance of persistence of all species - even the two smallest that were not affected by habitat loss alone - was disrupted by some combination of the four anthropogenic threats. Additive effects between anthropogenic threats were more important than their interaction in determining the occurrence of large mammals. While the effects of habitat loss were stronger than the effects of habitat fragmentation per se, road density was as important as habitat loss to species occurrence. Finally, there was no clear pattern in threat status or body size underlying the response of large mammals to combined anthropogenic threats. Our study suggest that protected areas in public or private lands in Amazonia should be large to secure the persistence of large mammals, but may include mosaics of primary and secondary forest. The findings also highlight the need to take into account the accumulated impacts of multiple threats simultaneously - particularly, the consequences of the expansion of the road network - in planning and management, as a way to avoid underestimating the chance of extinctions. Preventing Amazonian landscapes to become heavily deforested and altered is critical, as the persistence of even common species can be impaired, affecting one of the most important ecosystem services provided to local residents - bushmeat - and potentially eroding the value people attribute to forests

Advances in Information and Communication Technologies (ICTs) have brought many opportunities to South Africa and also challenges, such as narrowing the gap, known as the digital divide, between those who have (the “haves”) and those who do not have (the “have-nots”) access to ICTs. The majority of South Africans living in developing areas throughout South Africa do not have access to computers and are mostly computer illiterate. The Council for Scientific and Industrial Research (CSIR) launched their Digital Doorway project across South Africa to evaluate the feasibility of an alternative computer training method following a minimally invasive educational approach. Within the scope of the CSIR’s project, this research study endeavoured to explore to what extent and how the children had obtained computer skills, without the guidance of a facilitator, during the Digital Doorway project launched in Atteridgeville, Pretoria. A qualitative research methodology was adopted for the study. During the course of this research project, it was not possible to determine whether the children obtained any initial or additional computer skills, since the children were mostly unable to use the computers due to the malfunctioning thereof. The findings of this study coincide with authoritative literature on the topic which points out that real ICT access entails more than merely installing hardware and software. / Dissertation (MEd (Computer Assisted Education))--University of Pretoria, 2007. / Curriculum Studies / unrestricted