933 resultados para Statistical factora analysis
Resumo:
Em face da complexidade no ambiente de trabalho que exige maior dedicação por parte de seus ocupantes e com uma crescente exigência por desempenho destes indivíduos, o presente estudo teve por objetivo estudar a interdependência de algumas variáveis do comportamento organizacional, testando um modelo conceitual composto do capital psicológico, percepções de suporte e bem-estar no trabalho. Os participantes foram 152 trabalhadores que atuavam na Região Norte (Estado do Tocantins) e Região Sudeste (Estado de São Paulo) em organizações públicas e privadas. Como instrumento para coleta de dados foi utilizado um questionário de autopreenchimento composto de seis escalas que mediram as variáveis da pesquisa. A presente pesquisa se propôs a apresentar, interpretar e discutir as relações entre as variáveis, como também, testar as hipóteses referentes ao modelo conceitual proposto, por meio de uma pesquisa de natureza transversal com abordagem quantitativa, cujos dados coletados foram analisados por aplicação de técnicas estatísticas paramétricas (cálculos de estatísticas descritivas: médias, desvio padrão, teste t e correlações; cálculos de estatísticas multivariadas: análises de regressões lineares múltiplas hierárquicas e stepwise) por meio do software SPSS, versão 18.0. Os resultados obtidos demonstraram que os níveis das três dimensões de bem-estar no trabalho são impactados diretamente pelas percepções de suporte (social no trabalho e organizacional). Confirmou-se também, o capital psicológico como preditor direto das percepções de suporte (social no trabalho e organizacional). Por fim, este trabalho evidenciou que trabalhadores com um capital psicológico elevado tendem a perceber suporte, tanto social no trabalho como organizacional e, por conseguinte, trabalhadores que percebem suporte (social no trabalho e organizacional) tendem a manter vínculos com seu trabalho e com sua organização empregadora, os quais representam bem-estar no trabalho.
Resumo:
O objetivo geral deste estudo foi analisar, interpretar e discutir as relações entre a percepção de suporte organizacional, comprometimento organizacional afetivo e intenção de rotatividade e os efeitos das variáveis: gênero, idade, tempo de trabalho e chefia sobre a intenção de rotatividade. Participaram deste estudo 132 trabalhadores que atuam no estado de São Paulo em organizações públicas e privadas. Como instrumento para a coleta de dados foi utilizado um questionário de autopreenchimento composto por três escalas que mediram as variáveis. A presente pesquisa se propôs a apresentar, interpretar e discutir as relações entre as variáveis, como também, testar as hipóteses referentes ao modelo conceitual proposto, por meio de uma pesquisa de natureza transversal com abordagem quantitativa, cujos dados coletados foram analisados por aplicação de técnicas estatísticas paramétricas (cálculos de estatísticas descritivas: médias, desvio padrão, teste t student, correlações e cálculos de estatísticas multivariadas: analise da regressão múltipla hierárquica). O tratamento e análise dos dados foram realizados pelo software estatístico Statistical Package for Social Science SPSS, versão 19.0 para Windows. Os resultados obtidos demonstraram que percepção de suporte organizacional e o comprometimento organizacional são preditores diretos de intenção de rotatividade. As variáveis: gênero, idade, tempo de trabalho e chefia não apresentaram coeficientes de regressão significantes, portanto não é possível afirmar que são antecedentes de intenção de rotatividade. Os resultados foram discutidos à luz da literatura da área, tendo sido comparados com resultados de outros estudos empíricos.
Resumo:
A sociedade é digital e vivencia as benesses, desafios e paradigmas dessa era. As mudanças estão aceleradas e o tempo de adaptação a elas mais curto a cada dia. As relações comunicativas do homem com as máquinas estão se alterando de maneira profunda, com destaque para a multiplicação de telas audiovisuais que permeiam a vida das pessoas, as quais hoje são assessoradas por meio de inúmeros Assistentes Digitais Pessoais (PDAs) e outros displays ubíquos que convergem de forma radical entre si. A profusão tecnológica e apropriação sensorial dos instrumentos contemporâneos são exemplos tangíveis disso. Com tal cenário em primeiro plano, nossa pesquisa propõe contextualizar, descrever e analisar as novas faces e interfaces da comunicação que se materializam nas atuais plataformas audiovisuais digitais, cada vez mais móveis, conectadas e velozes. Dessa forma, empreende-se uma pesquisa exploratória que se valerá prioritariamente de levantamento bibliográfico específico e análise de dados estatísticos. A pesquisa indicou que as múltiplas telas, de fato, estão modificando a dinâmica dos processos comunicativos, os quais precisam ser recompreendidos.
Resumo:
Este estudo teve como objetivo principal analisar a relação entre a Liderança Transformacional, a Conversão do Conhecimento e a Eficácia Organizacional. Foram considerados como pressupostos teóricos conceitos consolidados sobre os temas desta relação, além de recentes pesquisas já realizadas em outros países e contextos organizacionais. Com base nisto identificou-se potencial estudo de um modelo que relacionasse estes três conceitos. Para tal considera-se que as organizações que buscam atingir Vantagem Competitiva e incorporam a Knowledge-Based View possam conquistar diferenciação frente a seus concorrentes. Nesse contexto o conhecimento ganha maior destaque e papel protagonista nestas organizações. Dessa forma criar conhecimento através de seus colaboradores, passa a ser um dos desafios dessas organizações ao passo que sugere melhoria de seus indicadores Econômicos, Sociais, Sistêmicos e Políticos, o que se define por Eficácia Organizacional. Portanto os modos de conversão do conhecimento nas organizações, demonstram relevância, uma vez que se cria e se converte conhecimentos através da interação entre o conhecimento existente de seus colaboradores. Essa conversão do conhecimento ou modelo SECI possui quatro modos que são a Socialização, Externalização, Combinação e Internalização. Nessa perspectiva a liderança nas organizações apresenta-se como um elemento capaz de influenciar seus colaboradores, propiciando maior dinâmica ao modelo SECI de conversão do conhecimento. Se identifica então na liderança do tipo Transformacional, características que possam influenciar colaboradores e entende-se que esta relação entre a Liderança Transformacional e a Conversão do Conhecimento possa ter influência positiva nos indicadores da Eficácia Organizacional. Dessa forma esta pesquisa buscou analisar um modelo que explorasse essa relação entre a liderança do tipo Transformacional, a Conversão do Conhecimento (SECI) e a Eficácia Organizacional. Esta pesquisa teve o caráter quantitativo com coleta de dados através do método survey, obtendo um total de 230 respondentes válidos de diferentes organizações. O instrumento de coleta de dados foi composto por afirmativas relativas ao modelo de relação pesquisado com um total de 44 itens. O perfil de respondentes concentrou-se entre 30 e 39 anos de idade, com a predominância de organizações privadas e de departamentos de TI/Telecom, Docência e Recursos Humanos respectivamente. O tratamento dos dados foi através da Análise Fatorial Exploratória e Modelagem de Equações Estruturais via Partial Least Square Path Modeling (PLS-PM). Como resultado da análise desta pesquisa, as hipóteses puderam ser confirmadas, concluindo que a Liderança Transformacional apresenta influência positiva nos modos de Conversão do Conhecimento e que; a Conversão do Conhecimento influencia positivamente na Eficácia Organizacional. Ainda, concluiu-se que a percepção entre os respondentes não apresenta resultado diferente sobre o modelo desta pesquisa entre quem possui ou não função de liderança.
Resumo:
2000 Mathematics Subject Classification: 62P10, 62J12.
Resumo:
Principal component analysis (PCA) is well recognized in dimensionality reduction, and kernel PCA (KPCA) has also been proposed in statistical data analysis. However, KPCA fails to detect the nonlinear structure of data well when outliers exist. To reduce this problem, this paper presents a novel algorithm, named iterative robust KPCA (IRKPCA). IRKPCA works well in dealing with outliers, and can be carried out in an iterative manner, which makes it suitable to process incremental input data. As in the traditional robust PCA (RPCA), a binary field is employed for characterizing the outlier process, and the optimization problem is formulated as maximizing marginal distribution of a Gibbs distribution. In this paper, this optimization problem is solved by stochastic gradient descent techniques. In IRKPCA, the outlier process is in a high-dimensional feature space, and therefore kernel trick is used. IRKPCA can be regarded as a kernelized version of RPCA and a robust form of kernel Hebbian algorithm. Experimental results on synthetic data demonstrate the effectiveness of IRKPCA. © 2010 Taylor & Francis.
Resumo:
AIDS education is mandated in schools throughout the United States to educate students about the disease. Teachers are expected to assume the major role of disseminating this information; therefore it is reasonable to question how knowledgeable teachers are about HIV/AIDS and where their information is coming from. This study explored the knowledge and attitudes of general and special education teachers toward students with HIV/AIDS and investigated whether a relationship between knowledge and attitudes existed. Information was collected using the AIDS Knowledge and Attitude Survey (AKAS). The sample was limited to certified teachers resulting in 318 participants.^ Research questions were analyzed using descriptive statistics, frequencies, t-tests, one-way analysis of variance (ANOVA), Scheffe post hoc analysis, and Pearson Product-Moment Correlation. Results indicated that general and special education teachers did not have complete knowledge about HIV/AIDS. Participants were knowledgeable regarding modes of transmission which may be the area of greatest concern for teachers, however, deficiencies were present within teachers' knowledge of general statements and facts and pathology. Among the ten demographic variables analyzed, six (gender, race/ethnicity, level of education, certification, instructional level taught, and classroom AIDS instruction) contained statistical significance.^ Analysis of attitudes indicated that general and special education teachers' overall attitudes toward students with HIV/AIDS were generally positive within clusters of Instruction and Fear, but not within Sensitivity and Communication. Among the ten demographic variables used for analysis only three (age, graduate enrollment status, and classroom AIDS instruction) produced statistical significance. Results found statistically significant relationships between Total Knowledge, all knowledge subtests, Fear, and Overall Attitudes. Statistical significance was also located on Total Knowledge, Pathology and Transmission knowledge subtests, and Sensitivity, as well as between Pathology and Instruction, and General Statements and Facts and Communication.^ The only variable determined to have statistical significance on both knowledge and attitudes was classroom AIDS instruction. Participants with previous AIDS instruction showed greater knowledge and possessed more positive attitudes. A review of previous research indicated training to be effective in increasing knowledge and fostering more favorable behavior toward persons with AIDS. Therefore, this study finds AIDS training to be beneficial for all teachers and is recommended during preservice education or through inservices for teachers already in the field. ^
Resumo:
To chronicle demographic movement across African Asian corridors, a variety of molecular (sequence analysis, restriction mapping and denaturing high performance liquid chromatography etc.) and statistical (correspondence analysis, AMOVA, calculation of diversity indices and phylogenetic inference, etc.) techniques were employed to assess the phylogeographic patterns of mtDNA control region and Y chromosomal variation among 14 sub-Saharan, North African and Middle Eastern populations. The patterns of genetic diversity revealed evidence of multiple migrations across several African Asian passageways as well within the African continent itself. The two-part analysis uncovered several interesting results which include the following: (1) a north (Egypt and Middle East Asia) to south (sub-Saharan Africa) partitioning of both mtDNA and Y chromosomal haplogroup diversity, (2) a genetic diversity gradient in sub-Saharan Africa from east to west, (3) evidence in favor of the Levantine Corridor over the Horn of Africa as the major genetic conduit since the Last Glacial Maximum, (4) a substantially higher mtDNA versus Y chromosomal sub-Saharan component in the Middle East collections, (5) a higher representation of East versus West African mtDNA haplotypes in the Arabian Peninsula populations versus no such bias in the Levant groups and lastly, (6) genetic remnants of the Bantu demographic expansion in sub-Saharan Africa. ^
Resumo:
Biological macromolecules can rearrange interdomain orientations when binding to various partners. Interdomain dynamics serve as a molecular mechanism to guide the transitions between orientations. However, our understanding of interdomain dynamics is limited because a useful description of interdomain motions requires an estimate of the probabilities of interdomain conformations, increasing complexity of the problem.
Staphylococcal protein A (SpA) has five tandem protein-binding domains and four interdomain linkers. The domains enable Staphylococcus aureus to evade the host immune system by binding to multiple host proteins including antibodies. Here, I present a study of the interdomain motions of two adjacent domains in SpA. NMR spin relaxation experiments identified a 6-residue flexible interdomain linker and interdomain motions. To quantify the anisotropy of the distribution of interdomain orientations, we measured residual dipolar couplings (RDCs) from the two domains with multiple alignments. The N-terminal domain was directly aligned by a lanthanide ion and not influenced by interdomain motions, so it acted as a reference frame to achieve motional decoupling. We also applied {\it de novo} methods to extract spatial dynamic information from RDCs and represent interdomain motions as a continuous distribution on the 3D rotational space. Significant anisotropy was observed in the distribution, indicating the motion populates some interdomain orientations more than others. Statistical thermodynamic analysis of the observed orientational distribution suggests that it is among the energetically most favorable orientational distributions for binding to antibodies. Thus, the affinity is enhanced by a pre-posed distribution of interdomain orientations while maintaining the flexibility required for function.
The protocol described above can be applied to other biological systems in general. Protein molecule calmodulin and RNA molecule trans-activation response element (TAR) also have intensive interdomain motions with relative small intradomain dynamics. Their interdomain motions were studied using our method based on published RDC data. Our results were consistent with literature results in general. The differences could be due to previous studies' use of physical models, which contain assumptions about potential energy and thus introduced non-experimental information into the interpretations.
Resumo:
An abstract of a thesis devoted to using helix-coil models to study unfolded states.\\
Research on polypeptide unfolded states has received much more attention in the last decade or so than it has in the past. Unfolded states are thought to be implicated in various
misfolding diseases and likely play crucial roles in protein folding equilibria and folding rates. Structural characterization of unfolded states has proven to be
much more difficult than the now well established practice of determining the structures of folded proteins. This is largely because many core assumptions underlying
folded structure determination methods are invalid for unfolded states. This has led to a dearth of knowledge concerning the nature of unfolded state conformational
distributions. While many aspects of unfolded state structure are not well known, there does exist a significant body of work stretching back half a century that
has been focused on structural characterization of marginally stable polypeptide systems. This body of work represents an extensive collection of experimental
data and biophysical models associated with describing helix-coil equilibria in polypeptide systems. Much of the work on unfolded states in the last decade has not been devoted
specifically to the improvement of our understanding of helix-coil equilibria, which arguably is the most well characterized of the various conformational equilibria
that likely contribute to unfolded state conformational distributions. This thesis seeks to provide a deeper investigation of helix-coil equilibria using modern
statistical data analysis and biophysical modeling techniques. The studies contained within seek to provide deeper insights and new perspectives on what we presumably
know very well about protein unfolded states. \\
Chapter 1 gives an overview of recent and historical work on studying protein unfolded states. The study of helix-coil equilibria is placed in the context
of the general field of unfolded state research and the basics of helix-coil models are introduced.\\
Chapter 2 introduces the newest incarnation of a sophisticated helix-coil model. State of the art modern statistical techniques are employed to estimate the energies
of various physical interactions that serve to influence helix-coil equilibria. A new Bayesian model selection approach is utilized to test many long-standing
hypotheses concerning the physical nature of the helix-coil transition. Some assumptions made in previous models are shown to be invalid and the new model
exhibits greatly improved predictive performance relative to its predecessor. \\
Chapter 3 introduces a new statistical model that can be used to interpret amide exchange measurements. As amide exchange can serve as a probe for residue-specific
properties of helix-coil ensembles, the new model provides a novel and robust method to use these types of measurements to characterize helix-coil ensembles experimentally
and test the position-specific predictions of helix-coil models. The statistical model is shown to perform exceedingly better than the most commonly used
method for interpreting amide exchange data. The estimates of the model obtained from amide exchange measurements on an example helical peptide
also show a remarkable consistency with the predictions of the helix-coil model. \\
Chapter 4 involves a study of helix-coil ensembles through the enumeration of helix-coil configurations. Aside from providing new insights into helix-coil ensembles,
this chapter also introduces a new method by which helix-coil models can be extended to calculate new types of observables. Future work on this approach could potentially
allow helix-coil models to move into use domains that were previously inaccessible and reserved for other types of unfolded state models that were introduced in chapter 1.
Acceptance of relapse fears in breast cancer patients: effects of an act-based abridged intervention
Resumo:
Objective: Relapse fear is a common psychological scar in cancer survivors. The aim of this study is to assess the effects of an abridged version of Acceptance and Commitment Therapy (ACT) in breast cancer patients.Method: An open trial was developed with 12 non-metastatic breast cancer patients assigned to 2 conditions, ACT and waiting list. Interventions were applied in just one session and focused on the acceptance of relapse fears through a ‘defusion’ exercise. Interference and intensity of fear measured through subjective scales were collected after each intervention and again 3 months later. Distress, hypochondria and ‘anxious preocupation’ were also evaluated through standardized questionnaires.Results: The analysis revealed that ‘defusion’ contributed to decrease the interference of the fear of recurrence, and these changes were maintained three months after intervention in most subjects. 87% of participants showed clinically significant decreases in interference at follow-up sessions whereas no patient in the waiting list showed such changes. Statistical analysis revealed that the changes in interference were significant when comparing pre, post and follow-up treatment, and also when comparing ACT and waiting list groups. Changes in intensity of fear, distress, anxious preoccupation and hypochondria were also observed.Conclusions: Exposure through ‘defusion’ techniques might be considered a useful option for treatment of persistent fears in cancer patients. This study provides evidence for therapies focusing on psychological acceptance in cancer patients through short, simple and feasible therapeutic methods.
Resumo:
Ankle sprains are the most common injuries in sports, usually causing damage to the lateral ligaments. Recurrence has as usual result permanent instability, and thus loss of proprioception. This fact, together with residual symptoms, is what is known as chronic ankle instability, CAI, or FAI, if it is functional. This problem tries to be solved by improving musculoskeletal stability and proprioception by the application of bandages and performing exercises. The aim of this study has been to review articles (meta-analisis, systematic reviews and revisions) published in 2009-2015 in PubMed, Medline, ENFISPO and BUCea, using keywords such as “sprain instability”, “sprain proprioception”, “chronic ankle instability”. Evidence affirms that there does exist decreased proprioception in patients who suffer from CAI. Rehabilitation exercise regimen is indicated as a treatment because it generates a subjective improvement reported by the patient, and the application of bandages works like a sprain prevention method limiting the range of motion, reducing joint instability and increasing confidence during exercise. As podiatrists we should recommend proprioception exercises to all athletes in a preventive way, and those with CAI or FAI, as a rehabilitation programme, together with the application of bandages. However, further studies should be generated focusing on ways of improving proprioception, and on the exercise patterns that provide the maximum benefit.
Resumo:
Understanding how aquatic species grow is fundamental in fisheries because stock assessment often relies on growth dependent statistical models. Length-frequency-based methods become important when more applicable data for growth model estimation are either not available or very expensive. In this article, we develop a new framework for growth estimation from length-frequency data using a generalized von Bertalanffy growth model (VBGM) framework that allows for time-dependent covariates to be incorporated. A finite mixture of normal distributions is used to model the length-frequency cohorts of each month with the means constrained to follow a VBGM. The variances of the finite mixture components are constrained to be a function of mean length, reducing the number of parameters and allowing for an estimate of the variance at any length. To optimize the likelihood, we use a minorization–maximization (MM) algorithm with a Nelder–Mead sub-step. This work was motivated by the decline in catches of the blue swimmer crab (BSC) (Portunus armatus) off the east coast of Queensland, Australia. We test the method with a simulation study and then apply it to the BSC fishery data.
Resumo:
Agricultural land has been identified as a potential source of greenhouse gas emissions offsets through biosequestration in vegetation and soil. In the extensive grazing land of Australia, landholders may participate in the Australian Government’s Emissions Reduction Fund and create offsets by reducing woody vegetation clearing and allowing native woody plant regrowth to grow. This study used bioeconomic modelling to evaluate the trade-offs between an existing central Queensland grazing operation, which has been using repeated tree clearing to maintain pasture growth, and an alternative carbon and grazing enterprise in which tree clearing is reduced and the additional carbon sequestered in trees is sold. The results showed that ceasing clearing in favour of producing offsets produces a higher net present value over 20 years than the existing cattle enterprise at carbon prices, which are close to current (2015) market levels (~$13 t–1 CO2-e). However, by modifying key variables, relative profitability did change. Sensitivity analysis evaluated key variables, which determine the relative profitability of carbon and cattle. In order of importance these were: the carbon price, the gross margin of cattle production, the severity of the tree–grass relationship, the area of regrowth retained, the age of regrowth at the start of the project, and to a lesser extent the cost of carbon project administration, compliance and monitoring. Based on the analysis, retaining regrowth to generate carbon income may be worthwhile for cattle producers in Australia, but careful consideration needs to be given to the opportunity cost of reduced cattle income.
Resumo:
As climate change continues to impact socio-ecological systems, tools that assist conservation managers to understand vulnerability and target adaptations are essential. Quantitative assessments of vulnerability are rare because available frameworks are complex and lack guidance for dealing with data limitations and integrating across scales and disciplines. This paper describes a semi-quantitative method for assessing vulnerability to climate change that integrates socio-ecological factors to address management objectives and support decision-making. The method applies a framework first adopted by the Intergovernmental Panel on Climate Change and uses a structured 10-step process. The scores for each framework element are normalized and multiplied to produce a vulnerability score and then the assessed components are ranked from high to low vulnerability. Sensitivity analyses determine which indicators most influence the analysis and the resultant decision-making process so data quality for these indicators can be reviewed to increase robustness. Prioritisation of components for conservation considers other economic, social and cultural values with vulnerability rankings to target actions that reduce vulnerability to climate change by decreasing exposure or sensitivity and/or increasing adaptive capacity. This framework provides practical decision-support and has been applied to marine ecosystems and fisheries, with two case applications provided as examples: (1) food security in Pacific Island nations under climate-driven fish declines, and (2) fisheries in the Gulf of Carpentaria, northern Australia. The step-wise process outlined here is broadly applicable and can be undertaken with minimal resources using existing data, thereby having great potential to inform adaptive natural resource management in diverse locations.