846 resultados para Functional-structural Plant Modelling


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1. The niche variation hypothesis predicts that among-individual variation in niche use will increase in the presence of intraspecific competition and decrease in the presence of interspecific competition. We sought to determine whether the local isotopic niche breadth of fish inhabiting a wetland was best explained by competition for resources and the niche variation hypothesis, by dispersal of individuals from locations with different prey resources or by a combination of the two. We analysed stable isotopes of carbon and nitrogen as indices of feeding niche and compared metrics of within-site spread to characterise site-level isotopic niche breadth. We then evaluated the explanatory power of competing models of the direct and indirect effects of several environmental variables spanning gradients of disturbance, competition strength and food availability on among-individual variation of the eastern mosquitofish (Gambusia holbrooki). 2. The Dispersal model posits that only the direct effect of disturbance (i.e. changes in water level known to induce fish movement) influences among-individual variation in isotopic niche. The Partitioning model allows for only direct effects of local food availability on among-individual variation. The Combined model allows for both hypotheses by including the direct effects of disturbance and food availability. 3. A linear regression of the Combined model described more variance than models limited to the variables of either the Dispersal or Partitioning models. Of the independent variables considered, the food availability variable (per cent edible periphyton) explained the most variation in isotopic niche breadth, followed closely by the disturbance variable (days since last drying event). 4. Structural equation modelling provided further evidence that the Combined model was best supported by the data, with the Partitioning and the Dispersal models only modestly less informative. Again, the per cent edible periphyton was the variable with the largest direct effect on niche variability, with other food availability variables and the disturbance variable only slightly less important. Indirect effects of heterospecific and conspecific competitor densities were also important, through their effects on prey density. 5. Our results support the Combined hypotheses, although partitioning mechanisms appear to explain the most diet variation among individuals in the eastern mosquitofish. The results also support some predictions of the niche variation hypothesis, although both conspecific and interspecific competition appeared to increase isotopic niche breadth in contrast to predictions that interspecific competition would decrease it. We think this resulted from high diet overlap of co-occurring species, most of which consume similar macroinvertebrates.

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Numerous studies have found a positive connection between learners’ motivation towards foreign language and foreign language achievement. The present study examines the role of motivation in receptive vocabulary breadth (size) of two groups of Spanish learners of different ages, but all with 734 hours of instruction in English as a Foreign Language (EFL): a CLIL (Content and Language Integrated Learning) group in primary education and a non-CLIL (or EFL) group in secondary education. Most students in both groups were found to be highly motivated. The primary CLIL group slightly overcame the secondary non-CLIL group with respect to the mean general motivation but this is a non-significant difference. The secondary group surpass significantly the primary group in receptive vocabulary size. No relationship between the receptive vocabulary knowledge and general motivation is found in the primary CLIL group. On the other hand, a positive significant connection, although a very small one, is identified for the secondary non-CLIL group. We will discuss on the type of test, the age of students and the type of instruction as variables that could be influencing the results.

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In the face of mass human rights violations and constant threats to security, there is growing recognition of the resilience of people and communities. This paper builds on such work by investigating the effects of individual coping strategies, perceived community cohesion, and their interaction on mental health symptoms in Colombia. The study was conducted five years after the mass demobilisation of the former paramilitaries and takes an exploratory quantitative approach to identify two distinct forms of coping approaches among participants living in the Caribbean coast of Colombia. A constructive coping approach included active engagement, planning behaviours, emotional support, acceptance and positive reframing of daily stressors. A destructive coping approach in this study entailed denial of problems, substance use and behavioural disengagement from day-to-day stress. In addition, the strength of perceived community cohesion, or how close-knit and effective the individuals feel about the community in which they live, was examined. Structural equation modelling revealed that a constructive coping approach was significantly related to lower depression, while a destructive coping approach predicted more symptoms of depression. Although there was not a significant direct effect of perceived community cohesion on mental health outcomes, it did enhance the effect of constructive coping strategies at the trend level. That is, individuals who used constructive coping strategies and perceived their communities to be more cohesive, reported fewer depression symptoms than those who lived in less cohesive settings. Implications for promoting constructive coping strategies, as well as fostering cohesion in the community, are discussed.

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Syria has been a major producer and exporter of fresh fruit and vegetables (FFV) in the Arabic region. Prior to 2011, Syrian FFV were mainly exported to the neighbouring countries, the Gulf States and Northern Africa as well as to Eastern European countries. Although the EU is potentially one of the most profitable markets of high quality FFV (such as organic ones) in the world, Syrian exports of FFV to Western European countries like Germany have been small. It could be a lucrative opportunity for Syrian growers and exporters of FFV to export organic products to markets such as Germany, where national production is limited to a few months due to climatic conditions. Yet, the organic sector in Syria is comparatively young and only a very small area of FFV is certified according to EU organic regulations. Up to the author’s knowledge, little was known about Syrian farmers’ attitudes towards organic FFV production. There was also no study so far that explored and analysed the determining factors for organic FFV adoption among Syrian farmers as well as the exports of these products to the EU markets. The overarching aim of the present dissertation focused on exploring and identifying the market potential of Syrian exports of organic FFV to Germany. The dissertation was therefore concerned with three main objectives: (i) to explore if German importers and wholesalers of organic FFV see market opportunities for Syrian organic products and what requirements in terms of quality and quantity they have, (ii) to determine the obstacles Syrian producers and exporters face when exporting agricultural products to Germany, and (iii) to investigate whether Syrian farmers of FFV can imagine converting their farms to organic production as well as the underlying reasons why they do so or not. A twofold methodological approach with expert interviews and a farmer survey were used in this dissertation to address the abovementioned objectives. While expert interviews were conducted with German and Syrian wholesalers of (organic) FFV in 2011 (9 interviews each), the farmer survey was administrated with 266 Syrian farmers of FFV in the main region for the production of FFV (i.e. the coastal region) from November 2012 till May 2013. For modelling farmers’ decisions to adopt organic farming, the Theory of Planned Behaviour as theoretical framework and Partial Least Squares Structural Equation Modelling as the main method for data analysis were used in this study. The findings of this dissertation yield implications for the different stakeholders (governmental institutions and NGOs, farmers, exporters, wholesalers, etc.) who are interested in prompting the Syrian export of organic products. Based on the empirical results and a literature review, an action plan to promote Syrian production and export of organic products was developed which can help in the post-war period in Syria at improving the organic sector.

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Objetivos: O presente estudo tem como objetivo analisar as redes sociais pessoais de idosos portugueses com filhos segundo o sexo da descendência e o sexo do/a idoso/a, relativamente às características estruturais, funcionais e relacionais-contextuais. Metodologia: Para a avaliação das variáveis em estudo foram utilizados o Instrumento de Análise da Rede Social Pessoal, versão para idosos (IARSP – Idosos) (Guadalupe, 2010; Guadalupe & Vicente, 2012) para avaliar as dimensões da rede social pessoal e um inquérito por questionário para caracterização da amostra a nível sociodemográfico e sociofamiliar. Participantes: A amostra é constituída por 498 idosos com filhos, com uma média de idades de 75 anos (DP=7,487), entre os 65 anos e os 98 anos, maioritariamente do sexo feminino (60,8%), casados ou em união facto (58,4%) e com escolaridade (70,7%). A maioria dos idosos inquiridos reside em aglomerado populacional (90,8%) e não usufrui de apoio de respostas sociais (78,1%). Resultados: Na análise separámos 3 subamostras: idosos com filhos de ambos os sexos (n=218; 43,7%), idosos com filhos do sexo masculino (n=125; 25,2%) e idosos com filhos do sexo feminino (n=155; 31,2%). Os idosos com filhas apresentam valores mais elevados no apoio material e instrumental (p = 0,046), apoio informativo (p = 0,018), companhia social (p = 0,018) e reciprocidade de apoio (p < 0,001). O tamanho da rede é menor no caso dos idosos com filhas comparativamente aos que têm filhos de ambos os sexos (p = 0,012). Analisando separadamente as redes das idosas e dos idosos da amostra, assinalamos que nas redes de idosos do sexo masculino apenas houve diferença na reciprocidade (p = 0,016), sendo menos recíprocas as redes da subamostra com filhos apenas do sexo masculino; por sua vez, nas redes das idosas houve diferenças no tamanho da rede (p = 0,015) e na frequência de contactos (p = 0,019) sendo maior nas idosas com filhos de ambos sexos; na proporção de relações de vizinhança na rede (p = 0,005), sendo menor nas idosas que têm filhos de ambos os sexos; no apoio informativo (p = 0,022) e na reciprocidade (p = 0,005) sendo menores nas idosas com filhos do sexo masculino. Conclusões: O nosso estudo revela que o sexo dos filhos influencia as redes sociais pessoais dos pais e mães idosos/as a nível funcional, estrutural e relacional-contextual, sobretudo no caso das mulheres idosas, uma vez que as redes das idosas apresentam diferenças nas três dimensões, o que não se verifica nos pais idosos, verificando-se também que os idosos com filhas do sexo feminino têm redes mais centradas nas relações familiares. / Goals: This study aims to analyze the personal social networks structural, functional and relational-contextual characteristics of Portuguese seniors with offspring, according to their sex. Methodology: To the variables evaluation, we have used the Personal Social Network Analysis Instrument, Elderly Version (IARSP – Elderly) (Guadalupe, 2010; Guadalupe & Vicente, 2012) in order to evaluate the dimensions of the personal social network, and a questionnaire for demographic description. Participants: Our sample has 498 seniors with offspring, with an average of 75 years of age (DP = 7,487), between 65 and 98 years old, mostly females (60,8%), married (58,4%) with education (70,7%).The majority live on agglomeration (90,8%) and does not have the support of social services (78,1%). Results: In this analysis we've 3 groups: seniors with sons and daughters (n = 218; 43,7%), seniors with male offspring (n = 125; 25,2%) and seniors with female offspring ( n = 155; 31,2%). Seniors with daughters only shows higher values on material and instrumental support (p = 0,046), informative support (p = 0,018), social company (p = 0,018) and reciprocity support (p < 0,001). The network size is smaller on senior's with offspring, comparing the ones with sons and daughters (p = 0,012). On a separate analysis of the male and female seniors sample, it should be noticed that on the male seniors network there's been a difference on reciprocity only (p = 0,016) being less reciprocal the networks from the group exclusively with male sons; on the other end, on the female seniors network with sons and daughters there's been a difference on the network size (p = 0,015) and on the contact frequency (p = 0,019) being smaller on the seniors with offspring from both sex; on the proportion relation of network neighborhood (p = 0,005), smaller on the female seniors with sons and daughters; on informative support (p = 0,022) and on the reciprocity (p = 0,005), being smaller on the female seniors with male offspring. Conclusions: Our study reveals that the male and female offspring influences the personal social networks of senior mothers and fathers on a functional, structural and context-relational level, mostly on women, once that their network presents differences in the three dimension, something that does not happen with senior fathers, with the verification that the seniors with daughters do have social networks that are more centered in family relations.

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Anchoíta (Engraulis anchoita) é uma espécie pelágica encontrada no Sudoeste do Oceano Atlântico. Estima-se que 135000 toneladas/ano desse peixe possam ser exploradas ao longo do litoral sul do Brasil. Entretanto, os recursos pesqueiros do país são ainda inexplorados, o que torna esta matéria prima candidata em potencial para a fabricação de novos produtos a base desse pescado. Com o apoio de programas governamentais sociais, a tendência para o Brasil é para o desenvolvimento de produtos de anchoíta alternativos e que sejam capazes de suprir as necessidades específicas de cada grupo de consumo alvo. Dentro desse cenário, um estudo de novos produtos de pescado frente ao mercado se faz necessário, na tentativa de compreender as variáveis influentes do setor. Para tanto, na presente tese teve objetivou-se desenvolver produtos à base de anchoíta e estudar o comportamento do mercado consumidor frente a esses novos produtos de pescado. Um total de seis artigos foi gerado. O primeiro artigo intitulou-se: “Potencial de inserção de empanados de pescado na merenda escolar mediante determinantes individuais”. Neste objetivou-se detectar os determinantes individuais do consumo de pescado com adolescentes em idade de 12 a 17 anos, visando à inserção de empanados de pescado na merenda escolar. Foi verificado que as variáveis que melhor discriminaram a frequência de consumo foram “gosta de pescado” e “grau de escolaridade dos pais”. Os resultados indicaram um potencial de consumo de empanados de pescado por adolescentes, associado à necessidade de educação alimentar. O segundo artigo “Elaboração de hambúrguer a partir de base proteica de anchoíta (Engraulis anchoita)” no qual se objetivou avaliar o efeito de diferentes combinações de solventes para a obtenção de base proteica de anchoíta visando à elaboração de hambúrguer de pescado. As lavagens com ácido fosfórico e mais dois ciclos de água foram as que apresentaram os melhores valores para a obtenção da base proteica, baseando-se na remoção de nitrogenados e respostas sensoriais. No terceiro artigo “Aceitação de empanados de pescado (Engraulis anchoita) na merenda escolar no extremo sul do Brasil” o objetivo foi avaliar a aceitação de empanados de pescado (Engraulis anchoita) com alunos (n = 830) da rede pública de ensino, em idades entre 5 e 18 anos, de duas cidades do estado do Rio Grande do Sul, Brasil. Os resultados indicaram relação inversa entre a aceitação de empanados de pescado e o aumento da idade das crianças. O quarto artigo estudou “Razões subjacentes ao baixo consumo de pescado pelo consumidor brasileiro.” Neste objetivou-se investigar o comportamento referente ao consumo de pescado de uma população com baixo consumo de pescado (Brasil), aplicando a Teoria do Comportamento Planejado (TCP). Os resultados indicaram que tanto a intenção como a atitude provou serem determinantes significativos na frequência de comer pescado, sendo a atitude inversamente correlacionada com o consumo de pescado. Hábito apareceu como uma importante variável discriminante para o consumo de pescado. O quinto artigo intitula-se “Modelagem de equações estruturais e associação de palavras como ferramentas para melhor compreensão do baixo consumo de pescado”. O objetivo foi desenvolver um modelo e explicar o conjunto das relações entre os construtos do consumo de pescado em uma população com baixo consumo de pescado (Brasil) através da aplicação da TCP e pelo Questionário das Escolhas dos Alimentos. Além disso, a percepção cognitiva de produtos de pescado (Engraulis anchoíta) foi avaliada pela mesma população. Os resultados indicaram um bom ajuste para o modelo proposto e mostraram que os construtos “saúde” e “controle de peso” são bons preditores da intenção. A técnica associação de palavras provou ser um método útil para a análise de percepção de um novo produto de pescado, além de ajudar a explicar os resultados obtidos pelas equações estruturais. O sexto e último artigo “Percepção de saudável em produtos de pescado em uma população com alto consumo de pescado. Uma investigação por eye tracking” em que se objetivou explorar o uso do método eye tracking para estudar a percepção de saudável em diferentes produtos de pescado. Dois pontos importantes podem ser salientados como influentes na percepção de saudável: produtos de pescado processados e alimentos fritos.

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It is important to assess young children's perceived Fundamental Movement Skill (FMS) competence in order to examine the role of perceived FMS competence in motivation toward physical activity. Children's perceptions of motor competence may vary according to the culture/country of origin; therefore, it is also important to measure perceptions in different cultural contexts. The purpose was to assess the face validity, internal consistency, test–retest reliability and construct validity of the 12 FMS items in the Pictorial Scale for Perceived Movement Skill Competence for Young Children (PMSC) in a Portuguese sample. Methods Two hundred one Portuguese children (girls, n = 112), 5 to 10 years of age (7.6 ± 1.4), participated. All children completed the PMSC once. Ordinal alpha assessed internal consistency. A random subsamples (n = 47) were reassessed one week later to determine test–retest reliability with Bland–Altman method. Children were asked questions after the second administration to determine face validity. Construct validity was assessed on the whole sample with a Bayesian Structural Equation Modelling (BSEM) approach. The hypothesized theoretical model used the 12 items and two hypothesized factors: object control and locomotor skills. Results The majority of children correctly identified the skills and could understand most of the pictures. Test–retest reliability analysis was good, with an agreement ration between 0.99 and 1.02. Ordinal alpha values ranged from acceptable (object control 0.73, locomotor 0.68) to good (all FMS 0.81). The hypothesized BSEM model had an adequate fit. Conclusions The PMSC can be used to investigate perceptions of children's FMS competence. This instrument can also be satisfactorily used among Portuguese children.

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The Questionnaire on the Frequency of and Satisfaction with Social Support (QFSSS) was designed to assess the frequency of and the degree of satisfaction with perceived social support received from different sources in relation to three types of support: emotional, informational, and instrumental. This study tested the reliability of the questionnaire scores and its criterion and structural validity. The data were drawn from survey interviews of 2042 Spanish people. The results show high internal consistency (values of Cronbach's alpha ranged from .763 to .952). The correlational analysis showed significant positive associations between QFSSS scores and measures of subjective well-being and perceived social support, as well as significant negative associations with measures of loneliness (values of Pearson's r correlation ranged from .11 to .97). Confirmatory factor analysis using structural equation modelling verified an internal 4-factor structure that corresponds to the sources of support analysed: partner, family, friends, and community (values ranged from .93 to .95 for the Goodness of Fit Index (GFI); from .95 to .98 for the Comparative Fit Index (CFI); and from .10 to .07 for the Root Mean Square Error of Approximation (RMSEA)). These results confirm the validity of the QFSSS as a versatile tool which is suitable for the multidimensional assessment of social support.

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This study proposes a conceptual framework that explores the correlations between economic dependence (ED), local government management of tourism (GMT), perceived tourism benefits and costs, and support for sustainable tourism development (STD). A quantitative research design was adopted. Data collection was carried out by personal survey applied to 300 residents of the small historic town of Lamego, located within the Douro Valley World Heritage Site. Structural equation modelling methods were employed to analyse the proposed model. Results suggest that GMT has a significant effect on the perceived impacts of tourism, both in the positive and in the negative. The effect of GMT in fostering residents’ support to STD was also empirically supported. Additionally, it was also determined that positive perceptions of the impacts of tourism directly influence support to STD. Nevertheless, ED does not have a significant effect either on perceivedbenefits, nor on perceived costs or on residents’ support to STD. Likewise, perceptions of the negative impacts do not predict residents’ support to STD.

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This cross-sectional study investigates the predictors of psychological symptoms-stress and depressive mood-in a sample of middle-aged women. A community sample of 1,003 women filled in the questionnaires and instruments, which included the Depression, Anxiety and Stress Scales and the Life Events Survey; sociodemographic, health, and menopause-related and lifestyle information was also collected. Structural equation modeling was used to build the model that had stress and depressive mood as dependent variables. Health status (both physical and psychological), recent life events, income and menopausal phase were significantly associated with the frequency of stress and depressive symptoms. Additionally, educational level and parity were also significant predictors of depressive mood. This study emphasizes that psychological symptoms occurrence in midlife depends not only on personal variables (such as health and menopausal status) but also on contextual ones (including recent stressful events) that can be a strong influence on how middle-aged women feel.

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Thesis submitted to University of Manchester for the degree of Doctor of Philosophy in the Faculty of Business Administration.

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Los turistas urbanos se caracterizan por ser uno de los segmentos de mayor crecimiento en los mercados turísticos actuales. Monterrey (México), uno de los principales destinos urbanos del país, ha apostado en la actualidad por mejorar su competitividad. Esta investigación se propuso encontrar evidencia acerca de la relación causal de la motivación de viaje sobre la imagen percibida del destino, dos variables importantes por su influencia en la satisfacción de los visitantes. Una revisión de la literatura permitió proponer constructos teóricos integrados en un instrumento para la recogida de datos vía encuesta a una muestra representativa. Por medio del método de regresión y ecuaciones estructurales por mínimos cuadrados parciales (PLS), se identificaron los componentes principales de ambas variables y se obtuvo un modelo explicativo de la imagen percibida del destino en función de la motivación de viaje. Finalmente, se emiten recomendaciones para la gestión del destino urbano en función de los resultados obtenidos. ABSTRACT: Abstract Urban tourists are recognized as one of the fastest growing segments in today’s tourism markets. Monterrey, Mexico, one of the main urban destinations in the country aims at improving its competitiveness. This research work had the purpose of finding evidence on the causal relationship between travel motivation and destination image, two important variables because of their influence on visitors’ satisfaction. A literature review enabled the proposal of a research instrument with theoretically based constructs to gather data through survey from a representative sample. Using regression and structural equations modelling by partial least squares (pls) a set of main components of both variables were identified thus enabling the obtention of a explanatory model of destination image in terms of travel motivations. Finally based on the results some recommendations of tourism management are given.

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Tese de dout. em Biologia, especialidade de Biologia Molecular, Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve

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Tese de Doutoramento, Turismo, Faculdade de Economia, Universidade do Algarve, 2016