3,343 research outputs found
R-covered foliations of hyperbolic 3-manifolds
We produce examples of taut foliations of hyperbolic 3-manifolds which are
R-covered but not uniform --- ie the leaf space of the universal cover is R,
but pairs of leaves are not contained in bounded neighborhoods of each other.
This answers in the negative a conjecture of Thurston `Three-manifolds,
foliations and circles I' (math.GT/9712268). We further show that these
foliations can be chosen to be C^0 close to foliations by closed surfaces. Our
construction underscores the importance of the existence of transverse
regulating vector fields and cone fields for R-covered foliations. Finally, we
discuss the effect of perturbing arbitrary R-covered foliations.Comment: 17 pages. Published copy, also available at
http://www.maths.warwick.ac.uk/gt/GTVol3/paper6.abs.htm
Lactobacillus crispatus as the etiological agent in cytolytic vaginosis
Introduction: Lactobacillus spp. dominate the vaginal niche but can also be involved in other vaginal dysbiosis, such as cytolytic vaginosis (CV), which remains poorly studied. It is characterized by a cryptic symptomatology, that often confounds the clinic.
Goals: The aim of this work was to search for the etiological agent of CV, by studying the vaginal microbiome and metabolomics of women afflicted with this disease and compare it with women with other clinical diagnostic.
Methods: Twenty-one vaginal washes have been collected from women attending a gynaecology consultation of a private clinic. The samples were categorized according with clinical diagnosis at the time of sampling (CV, 11; vulvovaginal candidosis, 8; Healthy, 2). The distribution of bacterial species, and their prevalence was assessed by next-generation sequencing of the 16S V4 region. In addition, total lactate D-lactic acid and L-lactic acid was quantified in all washes by a commercial kit, as well as lactate dehydrogenase (LDH) activity.
Results: L. crispatus was dominant (>70%) in all CV samples. Lactate was increased in CV in comparison with other cases. The presence of D-lactic acid isomer was associated with presence of L. crispatus. LDH activity was increased in vaginal washes that tested positive for the presence of L. crispatus, however no direct association was found with CV cases.
Discussion/Conclusions: The microbiome of women afflicted with CV was dominated in all cases by L. crispatus, contrarily with the results obtained for women diagnosed with other clinical symptomatology. In addition, the finding that an increase in D-lactic acid is associated with CV patients can be related to the role of L. crispatus in CV. The determination of LDH activity did not correlate exclusively with CV cases. On the other hand, D-lactic acid and total lactate quantification could be used as a valuable biomarker to diagnose this cryptic vaginal infection.info:eu-repo/semantics/publishedVersio
Antecedentes psicológicos de la lesión deportiva
Este estudio investigó a largo plazo, en el periodo de una época deportiva, los efectos de los acontecimientos vitales, capacidades de afrontamiento y personalidad en la predicción de las lesiones deportivas en 57 atletas de elite (nivel profesional y,o liga nacional), según lo teorizado en los modelos de Williams y Andersen (1998) y Wiese-Bjornstal y A. Smith (1993; 1998). Los cuestionarios que utilizamos fueron: Sport Experiences Survey (Smith, Ptacek y Smoll, 1992), Eysenk Personality Inventory (Eysenk y Eysenk, 1968), Athletic Coping Skills Inventory (Smith, Smoll, Ptacek y Schutz, 1995) y un cuestionario de datos generales. En una primera etapa intentamos, a través de un análisis de regresión, averiguar el ajuste de nuestros datos a los modelos arriba citados y, en una segunda, la combinación de las variables que identificasen mejor nuestros resultados. Los acontecimientos vitales moderaron las lesiones. El aumento de acontecimientos vitales negativos (EVN) estuvo asociado a mayores tasas de lésion, mientras que el aumento de acontecimientos vitales positivos (EVP) se asoció a menores tasas de lesión. Los más extrovertidos registraron menores tasas de lesión y rehabilitación más eficaces. La extroversión moderó los acontecimientos vitales, reduciendo la influencia de los EVN y originando los EVP. Las capacidades de afrontamiento se asociaron a tiempos de rehabilitación por abajo de los previstos, especialmente la dimensión Libertad de Preocupaciones. La percepción de mayores probabilidades de lesionarse se relacionó positivamente con la tasa de lesión y negativamente con los mejores resultados de rehabilitación.This investigation studied prospectively, during a sport season, the effect of life events, coping skills and personality on the prediction of sport injuries in 57 elite athletes (professional or national team level), as theorized in the Williams and Andersen model (1998). The article includes a brief discussion of some studies that lead to the elaboration of the model, specifically about the components: (a) stress response; (b) history of stressors; (c) personality; and (d) coping skills. We gathered data from: (a) life events (negative and positive); (b) extroversion and neuroticism; (c) coping skills in sport; and (d) demographics and some injury history related items. We have used a corrected injury measure (time loss/exposition time, named injury index) to avoid different practice time bias on our data. Our study has looked, through principal components, comparative, and regression analysis, for the adjustment of our data to the model and, secondly, seeks for a combination of variables that better identify our results. The life events moderated the injuries. Larger results on negative life events (NLE) were associated with bigger injury indexes, and larger numbers of positive life events (PLE) were associated to smaller injury indexes. The most extroverted have showed lesser injury indexes. The extroversion moderated life events, reducing the influence of NLE and enhancing the one from the PLE. The perception of larger probabilities of sustaining an injury was related positively to the injury index. We suggest future studies with prospective designs, with larger samples and repeated measures to build a thorough knowledge about this subject
The Low Energy Spectrum of Cosmic Rays as an Indicator of Primary Source Characteristics and Interstellar Propagation
Low energy spectrum of cosmic rays as indicator of primary source characteristics and interstellar propagatio
The Influence of Employment Protection and Firm-Level Factors on Labor Investment Decisions
[EN]In this research, we study the impact of business decisions on employment. We also argue the need to analyze how internal and external factors to the company condition its labor investment decisions. For this analysis, we focus on legal form, company size, and social responsibility as internal factors that may affect this type of investment. As external factors, we consider employment protection legislation in its different dimensions, such as protection of temporary employment, protection of the regular employee, and
protection of employment in general. The last one is a combination of different aspects of employee protection and incorporates restrictions on collective dismissal.
[ES]En este trabajo, estudiamos el impacto que tienen las decisiones empresariales en el empleo. También se argumenta la necesidad de analizar cómo los factores internos y externos a la empresa afectan a sus decisiones de inversión en mano de obra. Para nuestros análisis, nos centramos en la forma jurídica, el tamaño de la empresa y la responsabilidad social como factores internos que pueden afectar a este tipo de inversión. Como factores externos, consideramos la legislación de protección al trabajador en sus
distintas dimensiones (protección al empleo temporal, protección al empleado con contrato indefinido y protección al empleo en general), siendo la tercera una combinación de distintos aspectos sobre la protección al empleado, además de incorporar restricciones al despido colectivo
Is participatory design associated with the effectiveness of serious digital games for healthy lifestyle promotion? : a meta-analysis
Background: Serious digital games can be effective at changing healthy lifestyles, but large differences in their effectiveness exist. The extent of user involvement in game design may contribute to game effectiveness by creating a better fit with user preferences. Participatory design (PD), which represents active user involvement as informant (ie, users are asked for input and feedback) or codesigner (ie, users as equal partners in the design) early on and throughout the game development, may be associated with higher game effectiveness, as opposed to no user involvement or limited user involvement.
Objective: This paper reports the results of a meta-analysis examining the moderating role of PD in the effectiveness of serious digital games for healthy lifestyle promotion.
Methods: Four databases were searched for peer-reviewed papers in English that were published or in press before October 2014, using a (group-) randomized controlled trial design. Effectiveness data were derived from another meta-analysis assessing the role of behavior change techniques and game features in serious game effectiveness.
Results: A total of 58 games evaluated in 61 studies were included. As previously reported, serious digital games had positive effects on healthy lifestyles and their determinants. Unexpectedly, PD (g=0.075, 95% CI 0.017 to 0.133) throughout game development was related to lower game effectiveness on behavior (Q=6.74, P<.05) than when users were only involved as testers (g=0.520, 95% CI 0.150 to 0.890, P<.01). Games developed with PD (g=0.171, 95% CI 0.061 to 0.281, P<.01) were also related to lower game effectiveness on self-efficacy (Q=7.83, P<.05) than when users were not involved in game design (g=0.384, 95% CI 0.283 to 0.485, P<.001). Some differences were noted depending on age group, publication year of the study, and on the specific role in PD (ie, informant or codesigner), and depending on the game design element. Games developed with PD were more effective in changing behavioral determinants when they included users in design elements on game dynamics (beta=.215, 95% CI .075 to .356, P<.01) and, more specifically, as an informant (beta=.235, 95% CI .079 to .329, P<.01). Involving users as informants in PD to create game levels was also related to higher game effectiveness (Q=7.02, P<.01). Codesign was related to higher effectiveness when used to create the game challenge (Q=11.23, P<.01), but to lower game effectiveness when used to create characters (Q=4.36, P<.05) and the game world (Q=3.99, P<.05).
Conclusions: The findings do not support higher effectiveness of games developed with PD. However, significant differences existed among PD games. More support was found for informant roles than for codesign roles. When PD was applied to game dynamics, levels, and game challenge, this was associated with higher effectiveness than when it was applied to game aesthetics. Since user involvement may have an important influence on reach, adoption, and implementation of the intervention, further research and design efforts are needed to enhance effectiveness of serious games developed with PD
Low speed aerofoil optimization
Aerofoil shape has a significant influence on aircraft performance. Multiple methodologies
can be applied, such as direct design, inverse design or performance design. With the improvement of computer technology there has been a continuing trend of automating this process by using performancebased methods and formal optimisation algorithms. Parametrization formulations of aerofoils have continually advanced, some examples are BSpline, Class
Shape Functions, HicksHenne functions and BezierPARSEC 3333. Main comparisons of
parametrizations have focussed on morphology, design space and aerodynamic consistency.
In the present work, the parametrizations mentioned are applied to aerofoil optimisation
and their results compared for different numbers of design variables, in order to ascertain
optimisation differences. Performance design optimisation is used in a multipoint approach
with an aggregated objective function using weights that are determined using the aircraft
design data, to maximize the score for the competition Air Cargo Challenge (ACC2019 and
ACC2022), using XFOIL for aerodynamic analysis and particle swarm optimisation (PSO)
under a modified version of the XOPTFOIL tool. The initial aerofoil was obtained by iterative
inverse design during previous works, the optimisation includes the flap chord and deflection
angle for the different selected lift coefficient conditions as design variables. The initial population is bounded between maximum and minimum limits set by the initial aerofoil design
variables and an initial perturbation.
The aerofoil is constrained by minimum and maximum thicknesses, a minimum trailing edge
angle and a specified trailing edge thickness. Several additional restrictions are also imposed
on the aerofoil to avoid unneeded analysis of a geometry with an expected non converged solution in XFOIL. These include the angles’ maximum, minimum and difference values of the
two points closest to the leading edge, the maximum angle between any three consecutive
points and the number of curvature sign reversals at the upper surface and lower surface of
the aerofoil. To deal with the constraints and restrictions a penalty function is used, each
penalty being normalised by a maximum set value. To ensure that these do not unduly constrain the domain exploration of the optimisation, a dynamic limit to the penalties is used.
During the optimisation, this limit decreases linearly with the iterations.
From two case studies, it was possible to demonstrate the tool ability to optimize aerofoils.
In the first case, utilisation of BSplines achieved better results relative to the other methods.
In the second case, the dynamic limit, consistency method and XFOIL convergence recuperation method are studied. This last one has the greatest influence on optimisation.A topologia de perfis aerodinâmicos tem uma influência significativa no desempenho de
aeronaves. Múltiplas metodologias podem ser aplicadas para definir perfis, tais como projeto
direto, projeto inverso ou projeto por desempenho. Com o desenvolvimento da tecnologia
computacional, tem havido uma tendência contínua para automatizar o projeto de perfis utilizando projeto por desempenho e algoritmos de otimização formais. A parametrização de
perfis tem avançado lado a lado, alguns exemplos são BSpline, funções de tipo morfológicas, funções de HicksHenne e BezierPARSEC 3333. As principais comparações entre estes
métodos têmse focado na morfologia, espaço de projeto e consistência aerodinâmica.
No presente trabalho, os tipos de parameterização mencionados são utilizados para otimização de perfis e uma comparação é feita para diferentes números de variáveis com o objetivo de
avaliar diferenças para a otimização. Projeto por desempenho é utilizado numa abordagem
multiponto nesta dissertação, com uma função objetivo de agregação de pesos determinados
via dados de projeto da aeronave, para maximizar a pontuação para a competição Air Cargo
Challenge (ACC2019 e ACC2022), através do uso da ferramenta XFOIL para análise aerodinâmica e otimização por enxame de partículas sobre uma versão modificada da ferramenta
XOPTFOIL. O perfil inicial foi obtido via projeto inverso de forma iterativa durante trabalhos anteriores. A otimização inclui a corda do flap e o ângulo de deflexão para diferentes
condições de voo como variáveis de projeto. A população inicial é delimitada por limites
máximos e mínimos determinados através das variáveis de projeto do perfil inicial e uma
perturbação inicial.
O perfil é constrangido pelas máxima e mínima espessuras, um ângulo de bordo de fuga
mínimo e uma espessura de bordo de fuga fixa. Outras restrições adicionais são também
impostas ao perfil para evitar a análise desnecessária de geometrias cujo solução do XFOIL
não converge. Estas incluem os ângulos máximos, mínimos e a diferença dos dois pontos
mais próximos ao bordo de ataque, o ângulo máximo entre quaisquer três pontos ao longo
do perfil e o número máximo de mudanças de sinal da curvatura do perfil na superfície superior e inferior. Para lidar com estes constrangimentos e restrições utilizouse uma função
de penalidade com valores normalizados. De forma a garantir que estas não restringem o
domínio de exploração da otimização, um limite dinâmico é aplicado à função penalidade.
Este diminui linearmente durante a otimização.
A partir de dois casos de estudo é possível demonstrar a capacidade de otimização da ferramenta. No primeiro, o uso de BSplines alcançou melhores resultados comparativamente
aos outros métodos. No segundo, o limite dinâmico, método para consistência e método de
recuperação de convergência para a ferramenta XFOIL são estudados. Tendo este último o
maior efeito na optimização
O regime de comunicação prévia no combate ao planeamento fiscal abusivo
Esta tese tem como objecto o regime da comunicação prévia, introduzido em Portugal pelo Decreto-Lei nº 29/2008, de 25 de Fevereiro, e insere-se no âmbito do combate ao planeamento fiscal abusivo.O objecto do presente estudo é examinar o contexto, as características e as principais questões fiscais que originaram e decorrem do regime da comunicação prévia e questionar se o combate ao planeamento fiscal abusivo justifica ou não uma disposição especial anti-abuso que poderá também ela ser considerada abusiva. Este estudo realiza ainda uma análise comparada desta medida especial anti-abuso, com medida idêntica noReino Unido, país cuja Lei inspirou de forma mais expressiva a Lei Portuguesa.Este estudo centra-se na análise crítica do regime da comunicação prévia e identifica as principais questões suscitadas pelas suas regras, avalia as suas vantagens e fragilidades e retira conclusões sobre a eficácia, clareza e o rigor desta medida antiabuso.Além disso, este estudo analisa a compatibilização do regime da comunicação prévia, com o segredo profissional.Neste estudo conclui-se que é verdade que o regime da comunicação prévia, apresenta as mais diversas debilidades, devido, essencialmente, ao legislador Português, que vão desde falhas notórias de rigor e precisão, à falta de razoabilidade e ponderação, e que foram aqui, deveras, analisadas. Todavia, conclui-se também que este regime, recebendo as merecidas correcções, representará, como actualmente representa, um mecanismo de grande utilidade para a Administração Fiscal, no combate aoplaneamento fiscal abusivo, que só assumindo uma posição igualmente agressiva, poderá, pelo menos para já, tentar repor a integridade do sistema fiscal, a justadistribuição do encargo tributário e a pureza da actividade económica
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