Dissertations / Theses on the topic 'Individual use'

Species’ ranges arise from the interplay between environmental preferences, biotic and abiotic environmental conditions, and accessibility. Understanding of – and predictive models on – species distributions often build from the assumption that these factors apply homogenously within each species, but there is growing evidence for individual variation. Here, I use movement data to investigate individual-level decisions and compromises regarding the different costs and benefits influencing individuals’ geographic locations, and the species-level spatial patterns that emerge from these. I first developed a new method that uses tracking data to quantify individual specialisation in geographic space (site fidelity) or in environmental space (environmental specialisation). Applying it to two species of albatrosses, I found evidence of site fidelity but weak environmental specialisation. My results have implications for how limited research efforts are best-targeted: if animals are generalists, effort are best spent by understanding in depth individual patterns, i.e., better to track fewer individuals for long periods of time; whereas if animals tend to be specialists, efforts should be dedicated to tracking as many individuals as possible, even if for shorter periods. I then investigated individual migratory strategies and their drivers in nine North American bird species, using ringing/recovery data. I found latitudinal redistribution of individuals within the breeding and non-breeding ranges that generally did not follow textbook patterns (‘chain migration’ or ‘leapfrog migration’). Migratory individuals tend to trade off the benefits of migration (better tracking of climatic niche; better access to resources) and its costs (increasing with migratory distance). I found that birds are more likely to remain as residents in areas with warmer winter temperatures, higher summer resource surpluses and higher human population densities (presumably because of a buffering effect of urban areas). Overall, my results highlight the importance of considering individual variation to understanding the ecological processes underpinning species’ spatial patterns.

The purpose of this study was to explore the attitudes and practice of corporal punishment (CP) among Filipino parents and the factors that may impact their use of harsh punishment. Thirty-five parents, between the ages of 33 and 55 years old, participated in a group survey that was held in Manila, Philippines.

It was predicted that CP, as a form of discipline, would be prevalent among Filipino parents; it was also predicted that CP would be higher among parents of low economic status and that there were mitigating factors that impact Filipino parents' use of CP. Based on quantitative and qualitative analysis of the data collected, this study did not support all three hypotheses, although it showed that the use of CP was relatively high at 37%.

This study may provide evidence of a need for social support for both parents and children through family intervention programs and parenting training.

A major criticism of the environmental behavior literature is the nearly exclusive focus on the role of attitudes and individual-level characteristics. Despite this concentration on individual-level causes, variation in environmental behavior remains. As individual behavior becomes an increasingly significant source of pollution, a better understanding of the influences individual behavior is critical to addressing environmental degradation. This research re-directs the focus on individual-level influences on environmental behaviors by building models examining the varying dimensions of environmental behaviors as influenced by community characteristics. This is accomplished by testing a series of hypotheses under the auspices of two theoretical frameworks: the neoclassical economic theory and a social contextual model of environmental actions. Using individual-level data from the 1993 and 2000 General Social Survey and MSA data from the U.S. Census and the Environmental Protection Agency, I estimate two-level hierarchical models for three environmentally sensitive behaviors (environmentally sensitive food consumption, environmentally sensitive automobile use, and environmental activism). Multi-level analyses yield models revealing significant associations between MSA measures and individual environmental behaviors. Objective environmental conditions, region of MSA and MSA education level are significantly associated with environmentally sensitive food consumption behaviors, environmentally sensitive automobile use, and environmental activism behaviors, though their influence assumes diverse forms. Among the community measures, MSA education level is the primary social process that produces change in all environmental behaviors. In each of the models, MSA education level exhibits effects on all three behavioral measures and significant cross-level effects on automobile use behaviors. Living in a well educated MSA, particularly in the West or Northeast suggests higher environmental participation. Region of MSA is also a characteristic that must be considered when evaluating environmental behaviors, particularly for those living in the West and Northeast. Theoretical conclusions suggest that individual environmental behavior decision making is not simply a market exchange, but social forces are at work in the individual decision-making process.

Boys who were sexually abused in childhood are three times as likely to report substance use problems that are associated with poor mental and physical health as well as academic, vocational, and interpersonal difficulties. A review of literature revealed commonly held beliefs that (a) boys are not vulnerable to childhood sexual abuse; (b) boys are collaborators more so than victims; (c) sexual activity is a rite of passage for boys; (d) sexual activity is synonymous with masculinity. Self-blame may be the result of these patriarchal and misogynistic cultural norms. This study hypothesized that forgiveness can replace substance use as a coping strategy.

This research examined the relationship between substance use problems, family communication, and forgiveness in men who were sexually abused in childhood. The sample consisted of 406 men who completed an anonymous survey distributed via national support and advocacy organizations. Variables were measured with the CAGE-AID; the Family Communication Scale, Heartland Forgiveness Scale, and the Adverse Childhood Experiences Questionnaire. Three dimensions of forgiveness were assessed, (a) forgiveness of self; (b) forgiveness of others; (c) forgiveness of situations.

Findings revealed statistical significance (p = .030) that forgiveness of self is inversely related to substance use problems in men who were sexually abused in childhood. Logistic regression analysis indicated that family communication, forgiveness of others, and forgiveness of situations did not contribute to substance use problems in this sample. Results suggest that higher scores for forgiveness of self are related to lower rates of substance use problems.

As technology and capital markets complexity increases, so does the amount of accounting information disclosed by companies in their financial reports. Nowadays, we reached an impasse, where it is questionable if more information will in fact reduce information asymmetry. Previous authors strongly criticize the length of financial statements and annual reports, arguing that they should communicate more rather than just be voluminous as the current volume of information can be counterproductive to the average individual to acquire, retain and process all available information. Based on evidence of previous accounting literature on presentation format and the psychology theories of attribution theory and cognitive load theory, we hypothesize that, by manipulating accounting information using a more general accessible format such as the narrative one, individual investors are able to better understand accounting information and, thereafter, make a more effective use of it versus the concurrent non-fundamental information available in a standard investment decision making setting. To achieve our research goal, we use a mixed method research strategy with an Exploratory Sequential Design: the qualitative method act as a preparation for the quantitative one. Concerning the qualitative method, we interview- using the Q methodology approach - 31 subjects, being 13 analysts/professional investors and 18 individual investors. Our objective in this phase is to identify patterns in the usage of accounting/non-accounting information by analysts/professional investors, in contrast to individual investors\' information choices. By doing so, we can use the obtained results to base our experimental information choices regarding (a) which accounting information pieces were most preferable to professional investors and (b) the information presentation sequence to be followed in the experimental setting. Next, we develop a 2 X 2 between-subjects experimental design in which we manipulate the presentation format of a hypothetical company between the traditional \'tabular and footnotes\' design versus the narrative content-only design. We also vary the financial performance between \'good\' and \'bad\' to check if the variables of interest would impact (a) investment propensity on the company\'s shares and (b) the amount of information retrieved from memory. As our main results, we find that the narrative format per se does not impact investment propensity and that the alternative presentation format is beneficial for participants with less than 5 years of investment experience in capital markets in the poor financial performance condition, adjusting their investment propensity to the same investment propensity level of more experienced investors.
A medida que a complexidade da tecnologia e dos mercados de capitais aumentou, o montante da informação contábil divulgada pelas empresas em seus relatórios financeiros também aumentou. Atualmente, chegamos a um impasse, onde é questionável se mais informações reduzem a assimetria de informações. Autores anteriores criticam fortemente o tamanho das demonstrações financeiras e relatórios anuais, argumentando que eles devem comunicar mais ao invés de apenas serem volumosos, já que o atual volume de informações pode ser contraproducente para o indivíduo médio adquirir, reter e processar todas as informações disponíveis. Com base na evidência de literatura contábil anterior sobre o formato de apresentação e as teorias de psicologia, teoria da atribuição e teoria da carga cognitiva, temos a hipótese de que, ao manipular informações contábeis através de um formato amplamente mais acessível, como a narrativa, os investidores individuais serão capazes de compreender melhor as informações contábeis e, posteriormente, ter um uso mais proeminente delas em relação às atuais informações não fundamentais disponíveis para uma avaliação de decisão de investimento. Para alcançar nosso objetivo de pesquisa, utiliza-se uma estratégia de pesquisa de método misto com um Desenho Sequencial Exploratório, o método qualitativo atua como uma preparação para o quantitativo. Como método qualitativo, entrevistou-se - usando a abordagem da Metodologia Q - 31 sujeitos, sendo 13 analistas/investidores profissionais e 18 investidores individuais. O objetivo nesta fase foi entender o padrão de comportamento de uso de informações contábeis/não-contábeis por analistas/investidores profissionais, em comparação com as escolhas de informações de investidores individuais. Ao fazê-lo, puderam-se usar os resultados obtidos das entrevistas para basear as escolhas de informações experimentais em relação a (a) quais peças de informação contábil eram mais preferíveis aos investidores profissionais e (b) a sequência de apresentação de informações a seguir na configuração experimental. Em seguida, desenvolve-se um design experimental 2 x 2 entre os sujeitos em que manipulamos o formato de apresentação de uma empresa hipotética entre o design tradicional \'tabular e notas explicativas\' versus o design narrativo apenas de conteúdo. Foi alterado também o desempenho financeiro entre \'bom\' e \'ruim\' para verificar se as variáveis de interesse impactam (a) propensão de investimento nas ações da empresa e (b) a quantidade de informações recuperadas da memória. Como nossos principais resultados, identificamos que o formato narrativo individualmente não afeta a propensão de investimento e que o formato de apresentação alternativa beneficiou os participantes com menos de 5 anos de experiência de investimento nos mercados de capitais na condição de má performance financeira, ajustando sua propensão ao mesmo nível de investimento de investidores mais experientes.

The exceptions for individual use give rise to interesting and fundamental concerns drawing both international and national attention. There is uncertainty in the application of the individual use exceptions both in the international copyright treaties, particularly the three-step test of the Berne Convention, and in the national copyright legislation. To have a better understanding of this concerns, this thesis aims to: investigate whether the exceptions for individual use can still maintain the balance of interests between the copyright holders and users; analyse the contribution that international copyright agreements and national copyright legislation may have made to assist in solving the conflict of interest between right holder countries and user countries in applying the exceptions for individual use; and conduct a comparative study of the application of the individual use exceptions in developed and developing countries. The understandings that are found within this study are informed by relevant literature and by analysis of the application of the individual use exceptions. The thesis examines the application of the individual use exceptions in the international copyright treaties, namely, the Berne Convention, the TRIPS Agreement, and the WIPO Copyright Treaty in order to determine the appropriate ?balance? between the rights of owners and users in the three-step test. To explore the uncertainty in the individual use exceptions at the national level, a comparative case study is made between the exceptions for individual use in Australia, a developed country, and Thailand, a developing country. The results of the study reveal three major answers. First, the exceptions for individual use are able to still maintain the balance of interest between right holders and users in the digital environment, if some amendments are made to keep pace with the digital environment. Secondly, to assist in the solution to the conflict of interest between right holder countries and user countries in applying the exceptions for individual use, the international copyright agreements can make a contribution by making some minor changes, mainly in the three-step test of the Berne Convention, and by continuing to provide special treatments for developing countries. Nationally, the contribution may be made by thoroughly protecting the right holders whilst also still allowing individual use by amending the copyright legislation to update to the digital age when necessary, enacting the relevant Acts, and establishing a collecting society. Finally, from the comparison of the application of the exceptions for individual use as well as problems found and solutions proposed in developed and developing countries, in which Australia and Thailand are used as case studies, the comparison of the application of the exceptions for individual use can be divided into four categories: fair use exceptions (Australian fair dealing and Thai private use exceptions), free use exceptions, licences (Australian statutory licences and Thai compulsory licence), and limitation of legislative individual use provisions. In addition, the problem of different interpretations of the exceptions for individual use, the problem of conformity in the application of the exceptions for individual use according to the real purpose of the three-step test, which exists in Thailand, and the problem of response to the digital environment are all used as the frame for the comparison of the problems found and proposed solutions. The findings of the study are significant as they can provide contributions to the copyright areas primarily in the legal aspect: amendment of the exceptions for individual use. In addition, they also contribute to the related aspect in the copyright areas: the economic aspect: the balance between developed and developing Countries; and the moral aspect: developing countries? development. In addition, the thesis proposes four useful recommendations to enable the balance of interest between the right holders and the users to be maintained: amendment of the wording in the three-step test of the Berne Convention, amendment of domestic copyright law and its exceptions for individual use, encouragement of the role of collective management organisations, and raising public awareness on the issue of copyright and its exceptions for individual use.

It is well established that methadone maintenance (MM) reduces but does not eliminate the self-administration of other illicit drugs. For those on MM, there is considerable variation in consumption patterns, route of heroin administration, additional non-opioid substances routinely administered and the clinical disorders associated with these patterns of use. While there is a large literature base documenting these phenomena, studies have been almost exclusively descriptive in nature, with little attempt to develop a theoretical model in which to understand such use. In the following thesis, a model proposed by Gray was tested, the Reinforcement Sensitivity Theory (RST). This biopsychosocial model broadly describes two action tendencies; approach (Behavioural Activation System) and avoidance or withdrawal (Flight Fight Freeze System and the Behavioural Inhibition System). The model proposes that a heightened sensitivity to punishment underlies anxiety disorders. Conversely, a heightened sensitivity to rewarding stimuli may predispose some individuals to engage in highly rewarding behaviour and is associated with conduct disorder and antisocial personality disorder. According to the Joint Subsystems Hypothesis, these personality styles are mutually dependent, whereby BIS and BAS interact to influence reward mediated and punishment mediated behaviours. Based on Gray's model, this thesis tests whether opiate dependent individuals with heightened sensitivity to punishment are more likely to use anxiolytic drugs (such as benzodiazepines), and individuals with heightened reward sensitivity will show a preference for substances that have high reward potential (such as stimulants). At time one, the participant sample (N= 120) comprised 71 males (59%) and 49 females who were opioid dependent and recruitment took place over an eight-month period in two city opioid replacement clinics. A range of measures was administered to assess substance use, mood, anxiety and the personality dimensions of reward sensitivity and punishment sensitivity, with substance use again measured at three months. Results of the first study suggested that a large proportion of the variance was accounted for by personality within the models. A total of 98 participants (81%) participated in the 12-week follow-up study. Sensitivity to punishment and reward significantly predicted drug preference. Although psychopathology symptoms were not able to moderate the relationship between personality and drug use, anxiety symptoms negatively mediated the relationship between punishment sensitivity and anxiolytic use, whereby the relationship became non-significant. In contrast, sensitivity to reward remained the strongest predictor of amphetamine use over antisocial characteristics. Individual differences were not able to predict treatment retention nor susceptibility to relapse during a 12-week initiation to a MM programme.

Prognosis research summarises, explains and predicts future outcomes in patients with a particular condition. This thesis investigates the application and development of evidence synthesis methods for prognosis research, with particular attention given to improving individualised predictions from prognostic models developed and/or validated using metaanalysis techniques. A review of existing prognostic models for recurrence of venous thromboembolism highlighted several methodological and reporting issues. This motivated the development of a new model to address previous shortcomings, in particular by explicitly modelling and reporting the baseline hazard to enable individualised risk predictions over time. The new model was developed using individual participant data from several studies, using a novel internal-external cross-validation approach. This highlighted the potential for between-study heterogeneity in model performance, and motivated the investigation of recalibration methods to substantially improve consistency in model performance across populations. Finally, a new multiple imputation method was developed to investigate the impact of missing threshold information in meta-analysis of prognostic test accuracy. Computer code was developed to implement the method, and applied examples indicated missing thresholds could have a potentially large impact on conclusions. A simulation study indicated that the new method generally improves on the current standard, in terms of bias, precision and coverage.

This dissertation studies and identifies determinants of individual health. The first chapter analyzes how the supply of medical care affects patient treatment and health outcomes, focusing on how hospitals respond to the loss of a profitable service line. This chapter provides strong evidence that hospital spillovers across service lines are empirically important and that hospitals differentiate treatment by patient payer type. Hospitals practice both revenue augmenting and cost-cutting behavior in other lines of care, targeting specific procedures and payers according to their profitability. Specifically, they increase the number of surgical procedures and perform more marginal surgeries. The effects are concentrated in medical specialties where there are more discretionary surgeries and higher profit margins. Furthermore, hospitals cut back on unprofitable treatment by reducing non-elective admissions and uninsured elective care. Hospitals also increase the intensity of treatment among private payers. The second chapter of this dissertation investigates the demand side of health care, analyzing the role that health insurance plays on primary medical care usage by young American adults. I find office-based physician visits and prescription drugs are not affected by insurance, but dental visits are. There is a small increase in out-of-pocket expenditures caused by insurance loss, concentrated heavily at the top of the distribution. No change in health status or ability to afford care is found. The findings shed light on the expected welfare benefits of recent US health care policies targeting young adults. The final chapter of this dissertation analyzes the extent to which the early childhood environment shapes child health and development outcomes and, specifically, whether universal childcare levels the playing field across children. I analyze the introduction of a universal childcare program in Quebec in 1997, testing its impact on the distribution of child health and development outcomes. I find that there is little heterogeneity in the response to the policy across the distributions of child motor skills and cognitive outcomes. I do, however, find evidence that it led to a reduction in child body weight at the upper end of the distribution.
Arts, Faculty of
Vancouver School of Economics
Graduate

This study investigated parents’ experiences, challenges, benefits, and needs regarding their child’s voice output communication aid (VOCA). Three mothers who had children who use a VOCA device as their primary form of communication were recruited from Goodwill of Orange County’s Technology Exchange Center and Prentke Romich Company (PRC) and were interviewed by phone or email questionnaire. Thematic analysis of the interview data revealed four major themes: (a) benefits of VOCA use, (b) barriers to VOCA use, (c) facilitators of VOCA use, and (d) continuing needs of families. The information obtained from this study can be used to better serve families and children who use VOCAs and other AAC devices to avoid barriers (e.g., insufficient training) and abandonment and to foster more successful outcomes. Further research is necessary to continue to investigate the needs of parents in terms of their child’s device as well as the effectiveness of device training programs.

This thesis is concerned with understanding how the similarities, or differences, between small businesses working on transactional open-innovation projects might affect the dyadic performance. Specifically it explores whether varying degrees of difference, both at the organisational-level and at the individual personal-level, affects innovation performance and whether there is a ‘trade-off’ in innovation outcomes somewhere between high levels of similarity and difference. Empirical studies of similarity and difference have conflicting findings and most research into the particular condition of similarity and difference have taken place between multi-national businesses or in industries that have more formal innovation agendas, such as bio-technology or ICT. Additionally prior research has tended to evaluate a potential linear relationship between similarity variables and innovation performance. The study here draws on the Cognitive Theory of the Firm (Nooteboom, 2003) and its conceptual model of ‘cognitive distance’ which proposes that there is an inverted U-shaped relationship between the degree of difference in an innovation partnership and the innovation performance. It suggests a tipping point where performance improves up to a threshold and then begins to decline. The sample group is drawn from a cohort of small businesses based in the North-West of England taking part in an innovation voucher scheme designed to encourage linkages between small businesses and creative services suppliers. An analytical framework based on different measures and types of similarity is developed by reviewing a broad range of literature on innovation, open-innovation and small business innovation and these measures are used to assess innovation success against a range of six performance indicators. A major contribution of the research is the extension of the empirical domain for cognitive distance to the small and micro-business sector and further, the creation of a methodology which allows cognitive-distance to be directly measured, and performance assessed, at the level of the individuals within the innovation partnership. The relativity small sample group and the quite specific context requires the findings to be further corroborated but if results found here prove valid with other sample groups and within other contexts too, there may be implications in the future for how small firms might go about selecting their innovation partners.

Understanding the political nature of adult education program planning is important for practitioners and researchers. This multivariate study clarified the relationships between contextual factors (nature of the power relationship and degree of situational conflict), individual planner's characteristics (perceived problem solving effectiveness, years of experience program planning), and the use of different power and influencing tactics in adult education program planning. Based on theoretical models specified by Cervero and Wilson (1994) and later Yang (1996), the Problem Solving Inventory (Heppner, 1988) and the Power and Influencing Tactics Scale (Yang, 1996) provided instrumentation.A sample of 245 graduate students and faculty in Adult and/or Continuing Education programs completed the informed consent and all the self-report study instruments. Participants were middle-aged (M = 40.84), female (65.1%), and white (82.0%). Most held master's degrees (50.8%) or bachelor's degrees (41.1%) and worked in a public organization (57.1%) of moderate size. Most participants reported low conflict situations and strong perceived problem solving ability.Two significant canonical correlations were initially identified, though only the first held practical importance. In the first canonical correlation (Rc = 0.524; Rc ² = 0.275; p>0.01), high conflict was the singular meaningful predictor variable and there were several moderately strong criterion variables: high counteracting, low reasoning, and low consulting. This canonical correlation was named "When reasoning and consulting fail: counteracting in the face of conflict." Furthermore, in consensual planning situations, reasoning and consulting were favored, while counteracting was not. Three of the hypotheses that were generated to specifically test different uses of influencing tactics under different individual and contextual conditions were partially accepted. Being an early attempt to characterize complex constructs quantitatively, this study suggests that further work is needed to identify and measure the factors that are most critical. Future qualitative research should clarify the nature of power and conflict, and focus on describing the actual use of different influencing tactics in the field. Quantitative research should focus on reliability of instruments and theoretical model clarification with a broader range of adult education program planners.
Department of Educational Leadership

Thesis (Ph. D.)--Case Western Reserve University, 2008.
Weatherhead School of Management, Department of Information Systems. Includes bibliographical references. Available online via OhioLINK's ETD Center.

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The turnover intention refers to the probability of individuals leaving their current job. This topic has become relevant to organizations since it is a potential problem, which may affect the organizations competitiveness, amongst other reasons. It is believed that some of the individuals who have turnover intention look for means of communication, new technologies, such as the professional social network LinkedIn, in order to spread their professional information, find professional opportunities by networking, as well as obtain more information about the labor market, besides different other functions. Therefore, the turnover intention may be considered as a previous factor to the individual adoption of the professional social network LinkedIn. This study has analyzed the previous factors that may influence the usage and how they use the professional social network LinkedIn, guided by the theoretical perspective of the Unified Theory of Acceptance and Use of Technology (UTAUT), by Venkatesh et al (2003), and also guided by the scale of the turnover intention, by Siqueira et al (2014)and Van Dam (2008). The research is based on a quantitative investigation approach, in which data collection was done using a research tool, and obtained 292 answered questionnaires, which has made it possible to validate the relations between the constructs of the research model developed for the study of the individual adoption of the professional social network LinkedIn. There was an analysis of structural equations to make the test of the study hypotheses, based on PLS-PM (Partial Least Squares Path Modeling) from which satisfactory measures for all the investigated constructs and proposed models were presented, and all the relations between the constructs were significant. The results obtained by this study confirm the influence of previous factors, such as Performance Expectancy, Effort Expectancy, Social Influence, and Turnover Intention, on the intention of using the professional social network LinkedIn. The study concludes that the Performance Expectancy was revealed to be the greatest influence in the intention of using LinkedIn, since there is the perception that by using it, it is possible to obtain some professional benefits as well as other aspects. The second factor to present the greatest influence was the Turnover Intention, once some individuals, by adopting LinkedIn, may tend to show it to other people or organizations that are interested in their talents, experiences, skills, network and so on. The Effort Expectancy, in turn, showed that some individuals notice it is easy to interact with such technology, and the Social Influence showed that there is the individuals perception as to the influence of their network in their intention of using LinkedIn.
A intenção de rotatividade refere-se à probabilidade de os indivíduos deixarem o seu trabalho atual. Este tema se tornou relevante para as organizações por ser um potencial problema que pode afetar a competitividade das organizações, entre outros motivos. Acredita-se que alguns dos indivíduos com intenção de rotatividade possivelmente buscam meios de comunicação, novas tecnologias, como a rede social profissional LinkedIn objetivando disseminar suas informações profissionais, localizar oportunidades profissionais, obter mais contatos e informações sobre o mercado de trabalho, entre outras possibilidades. Desse modo, a intenção de rotatividade pode ser avaliada como um fator antecedente à adoção individual da rede social profissional LinkedIn. Este estudo analisou os fatores antecedentes que podem influenciar a intenção de uso e o comportamento de uso da rede social profissional LinkedIn, apoiando-se na perspectiva teórica da Teoria Unificada de Aceitação e Uso da Tecnologia (UTAUT), de Venkatesh et al (2003), e na escala de intenção de rotatividade, de Siqueira et al (2014) e Van Dam (2008). A pesquisa fundamenta-se em uma abordagem de investigação quantitativa na qual os dados foram coletados por meio de um instrumento de pesquisa com a obtenção de 292 questionários respondidos, o que possibilitou a validação dos relacionamentos entre os construtos componentes do modelo de pesquisa desenvolvido para o estudo da adoção individual da rede social profissional LinkedIn. Para realizar o teste das hipóteses do estudo, procedeu-se a análise de equações estruturais, com base no PLS-PM (Partial Least Squares Path Modeling) a partir do qual foram apresentadas medidas satisfatórias para os construtos investigados e o modelo proposto, sendo significativas todas as relações entre os construtos. Os resultados obtidos por esta pesquisa confirmam a influência dos fatores antecedentes Expectativa de Desempenho, Expectativa de Esforço, Influência Social e Intenção de Rotatividade na intenção de uso da rede social profissional LinkedIn. O estudo concluiu que Expectativa de Desempenho revelou-se o fator que mais influencia na intenção de uso do LinkedIn, pois há a percepção de que ao utilizar o LinkedIn pode-se obter benefícios profissionais, entre outros aspectos. O segundo fator que apresentou maior influência na intenção de uso do LinkedIn foi a intenção de rotatividade, uma vez que alguns dos indivíduos, ao adotarem o LinkedIn, provavelmente tendem a mostrar para as outras pessoas/organizações interessadas quais são os seus talentos, suas experiências, competências, além de obter mais contatos, entre outros motivos. Já a Expectativa de Esforço demonstrou que alguns indivíduos percebem que é fácil a interação desta tecnologia. A Influência Social constatou que existe a percepção dos indivíduos quanto à influência da sua rede de contatos na intenção de uso do LinkedIn.

Early research into the stable hydrogen isotopic compositions (δD) of petroleum involved bulk deuterium/hydrogen (D/H) measurements which, while providing some useful information, had to contend with the analysis of complex mixtures of hydrocarbons, and alteration resulting from the rapid exchange of nitrogen-, oxygen- and sulphur-bound hydrogen. The use of gas chromatography-isotope ratio mass spectrometry (GC-irMS) overcomes these problems by allowing the analysis of individual compounds containing only the most isotopically conservative aliphatic carbon-bound (C-bound) hydrogen. This project investigates the geochemical utility and reliability of compound-specific δD values, with the aim to better understand and exploit this analytical capability. To demonstrate the source diagnostic potential of compound-specific δD values, normal and branched alkanes extracted from series of immature bog-head coals (torbanites) were analysed. The torbanites contain immature organic matter predominantly from a single, freshwater algal source, i.e. Botryococcus braunii (B. braunii). The δD values of n-alkanes reflect the climate regime at the time of deposition of the torbanites, and vary mainly in response to the δD values of the source meteoric waters in their depositional environments. n-Alkanes from torbanites deposited at high latitude in a glacial climate are depleted in D by up to 70% relative to those from a torbanite deposited at low latitude under a tropical climate regime. Torbanites deposited in a mid-latitude region under cool-temperate conditions contain n-alkanes with δD values falling in between those of n-alkanes from tropical and glacial torbanites.
The δD values of the n-alkanes also reflect their multiple source inputs. For example, a saw-toothed profile of n-alkane δD values in Australian torbanites is attributed to a dual-source system: a predominant B. braunii input, with a minor terrestrial plant input to odd-carbon-numbered n-alkanes in the range n-C20 [subscript] to n-C29 [subscript]. The δD values of n-alkanes and isoprenoids (pristane and phytane) differ significantly in two Permian torbanites from Australia, thought to be reflective of the offset between the δD values of their precursors in extant organisms. The torbanite data indicate that a biological δD signal has been preserved for at least 260–280 million years, extending the utility of δD values for palaeoclimate studies. To elucidate the effect of sedimentary processes on the δD values of petroleum hydrocarbons, three sedimentary sequences have been studied. These comprise one from the Perth Basin (Western Australia) and two from the Vulcan Sub-basin (northern Australia) covering a wide range of maturities, i.e. 0.53–1.6% vitrinite reflectance (Ro). The δD values of n-alkanes extracted from immature-early mature sediments (marine shales/siltstones and mudstones) are consistent with that expected of marine-derived n-alkyl lipids. The hydrocarbons become enriched in D with increasing maturity. The large (ca. 115%) biologically-derived offset between the δD values of n-alkanes and acyclic isoprenoids from immature sediments gradually decreases with increasing maturity, as the isoprenoids become enriched in D more rapidly than the n-alkanes. The D-enrichment in isoprenoids correlates strongly with Ro and traditional molecular maturity parameters.
This suggests that H/D exchange during maturation occurs via a mechanism involving carbocation-like intermediates, which proceeds more rapidly with compounds containing tertiary carbon centres. Significant epimerisation of pristane and phytane coincides with their D-enrichment, suggesting that hydrogen exchange occurs at their tertiary carbons. A mechanism is proposed which can account for both H/D exchange and the epimerisation of pristane and phytane in the sedimentary environment. Pristane and phytane extracted from a post-mature sediment from the Paqualin-1 sequence are significantly enriched in D (ca. 40%) relative to the n-alkanes, indicating that D-enrichment persists at very high maturity, and is more pronounced for the regular isoprenoids than the n-alkanes. This supports the notion that H/D exchange causes the observed shift in δD values, rather than free-radical hydrogen transfer. The differences between the δD values of pristane and phytane show opposite trends in the Perth Basin and Vulcan Sub-basin sediments. In the Perth Basin, phytane is enriched in D relative to pristane, likely due to a dominant algal source. In the Vulcan Sub-basin, pristane is enriched in D relative to phytane, and thus is attributed to a lower relative input of algal organic matter. The variance of the δD values of pristane and phytane is generally consistent throughout the maturity range and provides evidence that pristane and phytane exchange hydrogen at similar rates. δD analysis of crude oils and condensates reservoired in the Perth Basin and Vulcan Sub-basin has been carried out to evaluate potential applications in oil-source correlation.
The n-alkanes from crude oils and condensates are often more enriched in D than n-alkanes extracted from their supposed source rocks, and the oils also show relatively small differences between the δD values of n-alkanes and isoprenoids. These results suggest significant H/D exchange has occurred, implying that the liquids were generated from mature source rocks. A Perth Basin crude oil (Gage Roads-1) thought to be derived from a lacustrine/terrestrial source contains hydrocarbons that are significantly depleted in D relative to Perth Basin oils derived from a marine source, attributed to variability in the isotopic composition of marine and terrestrial source waters. δD values of n-alkanes from Vulcan Sub-basin crude oils and condensates are largely consistent with their prior classification into two groups: Group A, having a marine source affinity; and Group B, having a terrigenous source affinity. Some oils and condensates are suggested to be mixtures of Group A and Group B hydrocarbons, or Group A hydrocarbons and other as yet unknown sources. An exception is a former Group A oil (Tenacious-1) containing n-alkanes that are enriched in D relative to those from other Group A oils and condensates, attributed to mixing with another source of more mature hydrocarbons. The n-alkane δD profile appears to be indicative of source and sedimentary processes. One Perth Basin crude oil (Dongara-14) contains lower-molecular-weight n-alkanes that are depleted in D relative to higher-molecular-weight n-alkanes, attributed to a mixed marine/terrestrial source.
Group A crude oils and condensates from the Vulcan Sub-basin display a ‘bowl-shaped’ profile of n-alkane δD values. An upward inflection in the n-alkane δD profile from n-C11 [subscript] to n-C15 [subscript] is suggested to represent the addition of D-enriched lower-molecular-weight n-alkanes from a more mature wet gas/condensate to an initial charge of lower maturity oil. Ultimately, this project has demonstrated that the δD values of individual petroleum hydrocarbons can be used to elucidate the nature of source organic matter and depositional environments. The preservation potential of lipid δD values is greater than previously thought, although it is clear that H/D exchange accompanying maturation can have a significant effect on the δD values of certain hydrocarbons. Thus, great care must be taken when interpreting δD values of individual hydrocarbons, particularly those derived from sediments of high thermal maturity.