11,070 research outputs found

    Open subgroups of the automorphism group of a right-angled building

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    We study the group of type-preserving automorphisms of a right-angled building, in particular when the building is locally finite. Our aim is to characterize the proper open subgroups as the finite index closed subgroups of the stabilizers of proper residues. One of the main tools is the new notion of firm elements in a right-angled Coxeter group, which are those elements for which the final letter in each reduced representation is the same. We also introduce the related notions of firmness for arbitrary elements of such a Coxeter group and nn-flexibility of chambers in a right-angled building. These notions and their properties are used to determine the set of chambers fixed by the fixator of a ball. Our main result is obtained by combining these facts with ideas by Pierre-Emmanuel Caprace and Timoth\'ee Marquis in the context of Kac-Moody groups over finite fields, where we had to replace the notion of root groups by a new notion of root wing groups.Comment: 29 page

    Stochastic group selection model for the evolution of altruism

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    We study numerically and analytically a stochastic group selection model in which a population of asexually reproducing individuals, each of which can be either altruist or non-altruist, is subdivided into MM reproductively isolated groups (demes) of size NN. The cost associated with being altruistic is modelled by assigning the fitness 1τ1- \tau, with τ[0,1]\tau \in [0,1], to the altruists and the fitness 1 to the non-altruists. In the case that the altruistic disadvantage τ\tau is not too large, we show that the finite MM fluctuations are small and practically do not alter the deterministic results obtained for MM \to \infty. However, for large τ\tau these fluctuations greatly increase the instability of the altruistic demes to mutations. These results may be relevant to the dynamics of parasite-host systems and, in particular, to explain the importance of mutation in the evolution of parasite virulence.Comment: 12 pages, 7 figure

    Método FMEA: Ferramenta de melhoria da Qualidade, Ambiente e Segurança numa PME

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    As Micro, Pequenas e Médias Empresas [PME] em Portugal assumem um papel de destaque no contexto empresarial português, contudo diversos fatores aliados a uma conjuntura económica delicada, tornam estas organizações vulneráveis. A globalização dos mercados impeliu estas empresas para uma visão de gestão mais universal, traduzindo-se, nos últimos anos, num aumento generalizado de certificações nos mais diversos referenciais normativos, salientando-se os sistemas de gestão que integram duas ou mais normas. A aposta das organizações em Sistemas Integrados de Gestão reflete a tendência de alinhamento de requisitos, patente nas últimas revisões dos documentos normativos. O presente projeto aplicado teve como objetivo aplicar uma ferramenta de diagnóstico e avaliação de potenciais falhas num processo de uma PME, que, simultaneamente integrasse as áreas da Qualidade, Ambiente e Segurança. Com base na metodologia de Análise dos Modos de Falha e seus Efeitos (Failure Mode and Effect Analysis [FMEA]), foram identificados os modos de falha ao nível da Qualidade (defeitos), Ambiente (impactes ambientais) e ao nível da Segurança, Higiene e Saúde do trabalho (riscos profissionais), em cada fase de um processo de injeção de um componente em borracha e avaliados os respetivos índices de gravidade, ocorrência e deteção. Posteriormente determinou-se o número de prioridade de risco que indicou quais as fases do processo em que era necessário desencadear ações para eliminar ou reduzir o risco. A simplicidade de aplicação desta metodologia permitiu a sua otimização traduzida na avaliação simultânea dos riscos de qualidade, ambiente e segurança, reduzindo o tempo, otimizando recursos e traduzindo-se em ações de melhoria efetiva do processo, tornando-o mais estável e robusto em todas as suas vertentes e, consequentemente, contribuindo para a obtenção de resultados benéficos para a organização

    A avaliação do conhecimento gramatical 'oficial': estudo dos exames nacionais de Português de 2010

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    Na última década e a nível nacional, as provas de aferição e os exames nacionais vêm sendo objecto de polémicas, vindas de distintos quadrantes e de que é exemplo o editorial do jornal Público de 22/6/2009: “Exames 2009: como se prepara o ‘sucesso’ fácil”. Em termos da avaliação educacional, se aceitarmos que “a avaliação é sinónimo de sucesso” (Pacheco & Zabalza, 1995: 7), tal significará que, ao estudar a avaliação externa, poderemos contribuir para uma compreensão sustentada da educação em línguas. Além disso, entendendo a avaliação do conhecimento gramatical “oficial” como um factor constitutivo das disciplinas de Português, será possível descrever como são representados e avaliados os conhecimentos explícitos sobre o ensino da língua materna. Neste quadro, pretende-se, neste estudo, aprofundar a análise do domínio da gramática em provas de avaliação externa, comparando as provas de aferição de Língua Portuguesa do 4º e do 6º anos de escolaridade e os exames do 9º e do 12º anos, todos realizados no ano lectivo de 2009/2010. Com esta finalidade, o trabalho desenvolver-se-á de acordo com as seguintes dimensões de análise: a) delimitação da estrutura das diferentes provas de avaliação em Português, de acordo com domínios correntes como a leitura, a escrita ou a gramática; b) identificação dos tipos de pergunta e dos conteúdos implicados na avaliação do saber gramatical; c) categorização das questões segundo três níveis - reconhecimento, produção e explicitação dos conhecimentos sobre a língua. Para além de compreender melhor o papel da regulação externa dos saberes relativos ao conhecimento explícito da língua, deste estudo retirar-se-ão conclusões acerca das novas formas de (re)configuração da gramática escolar

    Caso Clínico de una Niña con Algoneurodistrofia

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    A clinical case of a 12-year-old female child with anxiety symptoms and a diagnosis of Algoneurodystrophy in the left hand is presented. The psychological assessment was carried out using the following instruments: observation, psychological interview, Wechsler Intelligence Scale for Children (WISC-III), State/Trait Anxiety Questionnaire for children, and Conners Scales for parents and teachers. The intervention aimed to reduce anxiety levels, promote self-esteem, and alleviate the child's grief. For this purpose, a cognitive-behavioral intervention was carried out with the child and their parents. Through education, the child's parents were alerted to the need to express the feeling of loss, providing an environment for the resolution of the grieving process of all family members. Furthermore, they were also warned about the maintenance factors of the child's anxiety symptoms, such as the issue of high parental demand. As a result, it can be concluded that good therapeutic gains were seen, translating into the resolution of the child's problems and, consequently, increasing their psychological well-being.Se presenta el caso clínico de una niña de 12 años con síntomas de ansiedad y diagnóstico de algoneurodistrofia en la mano izquierda. La evaluación psicológica se realizó mediante los siguientes instrumentos: observación, entrevista psicológica, Escala de Inteligencia Wechsler para Niños (WISC-III), Cuestionario de Ansiedad Estado/Rasgo para niños y Escalas de Conners para padres y profesores. La intervención tuvo como objetivo reducir los niveles de ansiedad, promover la autoestima y aliviar los sentimientos de dolor. Para ello, se realizó una intervención cognitivo-conductual con la niña y los padres.  A través de la educación, los padres de la niña fueron alertados sobre la necesidad de expresar el sentimiento de pérdida, brindando un entorno para la resolución del proceso de duelo de todos los miembros de la familia. Además, también se les advirtió sobre los factores de mantenimiento de los síntomas de ansiedad de la niña, como el tema de la alta demanda de los padres. Como resultado, se puede concluir que se apreciaron buenos avances terapéuticos, que se tradujeron en la resolución de los problemas de la niña y, en consecuencia, en un aumento de su bienestar psicológico

    Rice husk, brewer’s spent grain, and vine shoot trimmings as raw materials for sustainable enzyme production

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    Solid by-products with lignocellulosic structures are considered appropriate substrates for solid-state fermentation (SSF) to produce enzymes with diverse industrial applications. In this work, brewer’s spent grain (BSG), rice husk (RH), and vine shoot trimmings (VSTs) were employed as substrates in SSF with Aspergillus niger CECT 2088 to produce cellulases, xylanases, and amylases. The addition of 2% (NH4)2SO4 and 1% K2HPO4 to by-products had a positive effect on enzyme production. Substrate particle size influenced enzyme activity and the overall highest activities were achieved at the largest particle size (10 mm) of BSG and RH and a size of 4 mm for VSTs. Optimal substrate composition was predicted using a simplex centroid mixture design. The highest activities were obtained using 100% BSG for β-glucosidase (363 U/g) and endo-1,4-β-glucanase (189 U/g), 87% BSG and 13% RH for xylanase (627 U/g), and 72% BSG and 28% RH for amylase (263 U/g). Besides the optimal values found, mixtures of BSG with RH or VSTs proved to be alternative substrates to BSG alone. These findings demonstrate that SSF bioprocessing of BSG individually or in mixtures with RH and VSTs is an efficient and sustainable strategy to produce enzymes of significant industrial interest within the circular economy guidelines.This study was funded by the Recovery and Resilience Plan (PRR), Next Generation EU, for the period 2021–2026, through the integrated project be@t—Textile Bioeconomy (TC-C12-i01, Sustainable Bioeconomy No. 02/C12-i01/2022), and by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit (DOI 10.54499/UIDB/04469/2020).info:eu-repo/semantics/publishedVersio

    Moving forward with solar cooking: closing knowledge gaps in technical, environmental and food quality aspects

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    Background: Solar cooking is a method that makes use of the sun's energy to cook food. Unlike traditional cooking methods that rely on non-renewable energy sources, solar cookers only require sunlight. Solar cookers are environmentally friendly and help reduce greenhouse gas emissions. Additionally, solar cooking helps preserve natural resources by reducing consumption of non-renewable energy. Despite the apparent benefits of solar cooking, some knowledge gaps remain regarding technical complexities, sustainability implications, and the impact on food nutritional quality. Methods: An extensive literature review was conducted to comprehend the existing solar cooking knowledge. It examined scientific research available until December 31st, 2023. Results: Extensive research has been carried out on heat transfer in solar cooking, but there is still a lack of knowledge regarding the behaviour of food cooked with solar energy. The intricate interplay of dynamic variables affecting solar cookers' energy and food quality performance makes integrating this aspect with existing studies difficult. It is crucial to perform modeling studies of the thermal and quality behaviour of the food prepared in each type of solar cooker. Innovative approaches such as machine learning can be identified as promising tools. Conclusions: To increase the global use of solar cooking, presenting it as a viable solution for cooking- related challenges is essential, emphasizing its positive social and environmental impacts. Although some research works on the thermal performance of solar cookers are available, research on the modeling and simulation of time.info:eu-repo/semantics/publishedVersio

    Supplier selection and procurement in SMEs: Insights from the literature on key criteria and purchasing strategies

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    Effective strategic purchasing and supplier selection in companies provides businesses with leverage in acquiring goods and services. Thus, companies are in a better position to negotiate prices, discounts, delivery times and logistic channels. Also, strategic purchasing allows for performing a risk assessment to ensure the company's profitability. This research aimed to identify the key currently deliberated by SMEs for supplier selection, considering such purchasing strategies as (1) cost reduction, (2) risk management, (3) global sourcing, (4) total quality management, (5) sustainable management and (6) supplier management. Also, it aimed to identify the emerging issues related to purchasing strategies. This research work performed a content analysis following a literature review. The Scopus indexation database was selected to conduct the document search. After the refinement process, based on 59 analysed documents, bibliometric assessment tools were applied to identify the key criteria for supplier selection. The TOP6 highest ranked criteria, which corresponds to 80 % of the most referred criteria, include: (1) the quality of goods; (2) compliance with the delivery times; (3) price/cost; (4) supplier reputation and/or market positioning; (5) geographical location; and (6) supplier performance history. The goal of strategic purchasing is to support the companies in achieving long-term goals through its integration into the company's strategic planning process. It should be identified by the managers as an important resource. Several factors elevate the importance of strategic purchasing, namely, environmental protection, technology advances related to logistics 4.0, and risk assessment related to global sourcing and sustainability. The present research is in line with the findings of the referred literature, i.e., the application of prioritised criteria for the procurement and supplier selection operations in the industrial context, aiming to reduce lead times and logistic costs. The criteria must be aligned w- (undefined
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