1,783 research outputs found
Dynamics of active membranes with internal noise
We study the time-dependent height fluctuations of an active membrane
containing energy-dissipating pumps that drive the membrane out of equilibrium.
Unlike previous investigations based on models that neglect either curvature
couplings or random fluctuations in pump activities, our formulation explores
two new models that take both of these effects into account. In the first
model, the magnitude of the nonequilibrium forces generated by the pumps is
allowed to fluctuate temporally. In the second model, the pumps are allowed to
switch between "on" and "off" states. We compute the mean squared displacement
of a membrane point for both models, and show that they exhibit distinct
dynamical behaviors from previous models, and in particular, a superdiffusive
regime specifically arising from the shot noise.Comment: 7 pages, 4 figure
Anomalous Higgs Couplings
We review the effects of new effective interactions on the Higgs boson
phenomenology. New physics in the electroweak bosonic sector is expected to
induce additional interactions between the Higgs doublet field and the
electroweak gauge bosons leading to anomalous Higgs couplings as well as to
anomalous gauge-boson self-interactions. Using a linearly realized invariant effective Lagrangian to describe the bosonic sector of
the Standard Model, we review the effects of the new effective interactions on
the Higgs boson production rates and decay modes. We summarize the results from
searches for the new Higgs signatures induced by the anomalous interactions in
order to constrain the scale of new physics in particular at CERN LEP and
Fermilab Te vatron colliders.Comment: 35 pages, latex using epsfig.sty psfig.sty and axodraw.sty, 16
postscript figure
Modelagem matemática da contração volumétrica de grãos de sorgo
A qualidade dos grĂŁos de sorgo, bem como a dos demais produtos agrĂcolas Ă© função dos fatores prĂ©-colheita, da colheita propriamente dita e da pĂłs-colheita. Na fase de pĂłs-colheita a secagem Ă© o processo mais utilizado para assegurar a qualidade e estabilidade dos produtos agrĂcolas. A secagem Ă© definida como um processo simultâneo de transferĂŞncia de calor e massa entre o produto e o ar de secagem. Um processo de secagem eficiente reduz a atividade de água do produto, aumenta seu potencial de conservação pĂłs-colheita preservando suas caracterĂsticas fĂsicas e propriedades tecnolĂłgicas, possibilitando uma armazenagem segura. PorĂ©m se a secagem nĂŁo for bem conduzida pode acarretar em perdas de qualidade, devido Ă s alterações fĂsicas quĂmicas e sensoriais que pode provocar. A perda de água causa danos Ă estrutura celular do produto levando Ă mudanças na forma e ao decrĂ©scimo em suas dimensões, a redução do conteĂşdo de água durante o processo de secagem gera uma redução no tamanho do tecido celular, fenĂ´meno este que usualmente Ă© chamado de contração volumĂ©trica. As variações volumĂ©tricas dos produtos, devido Ă sua desidratação, sĂŁo relatadas como uma das principais causas de alterações nas principais propriedades fĂsicas dos produtos agrĂcolas. Diante disso, objetivou-se com o presente trabalho avaliar e modelar a contração volumĂ©trica de grĂŁos de sorgo durante o processo de secagem. Foram utilizados grĂŁos de sorgo (Sorghum bicolor) colhidos e debulhados manualmente das cultivares BRS 308 e Nidera A 9721, procedentes de um plantio experimental da Embrapa Agrossilvipastoril e de um cultivo comercial, respectivamente, ambos na cidade de Sinop (MT). A secagem dos grĂŁos de sorgo foi realizada em uma estufa com circulação forçada de ar, nas temperaturas de 40, 50 e 60 °C, sendo o teor de água acompanhado por diferença de massa, conhecendo-se o teor de água inicial do produto. O volume da massa de grĂŁos de sorgo foi medido ao longo do processo de secagem utilizando-se uma proveta graduada com volume de 1000 ± 5 mL. A avaliação dos modelos de contração volumĂ©trica utilizados foi realizada mediante a determinação e análise do erro cometido na estimação dos dados observados (erro mĂ©dio relativo e desvio padrĂŁo da estimativa), na magnitude do coeficiente de determinação e na significância dos parâmetros pelo teste ?t?. Baseando-se nos Ăndices estatĂsticos propostos o modelo linear foi o que melhor descreveu a contração volumĂ©trica da massa de grĂŁos de sorgo ao longo do processo de secagem para as duas variedades e nas condições em que foi realizado o experimento
Effect of Parathion-Methyl on Amazonian fish and freshwater invertebrates: a comparison of sensitivity with temperate data.
Parathion-methyl is an organophosphorous insecticide that is widely used in agricultural production sites in the Amazon. The use of this pesticide might pose a potential risk for the biodiversity and abundance of fish and invertebrate species inhabiting aquatic ecosystems adjacent to the agricultural fields. Due to a lack of toxicity data for Amazonian species, safe environmental concentrations used to predict the ecological risks of parathion-methyl in the Amazon are based on tests performed with temperate species, although it is unknown whether the sensitivity of temperate species is representative for those of Amazonian endemic species
COVID-19 and chronic diabetes: The perfect storm for reactivation TB?
Background: The Coronavirus disease 2019 (COVID-19) pandemic is predicted to have a net negative effect on tuberculosis (TB) control, with an estimated excess of 6.3 million tuberculosis cases and 1.4 million deaths by 2025. Programmatic issues like the lockdown of TB services affect all patients, while biosocial factors have a differential impact on an individual’s risk for TB or adverse TB outcomes.
Case presentation: We report three cases of incident TB after resolution of COVID-19 episodes.Coincidently, all cases shared a common risk factor: a chronic history poorly-controlled diabetes.
Conclusions: Our findings alert to the threat posed by the synergy between COVID-19 and diabetes, on TB reactivation. In medium- to high-risk settings for TB, we recommend implementation of routine screening for latent TB infection in these cases, and preventive TB treatment in those who are positive.
Published version of this presentation: AguillĂłn-Durán, G.P., Prieto-MartĂnez, E., Ayala, D. et al. COVID-19 and chronic diabetes: the perfect storm for reactivation tuberculosis?: a case series. J Med Case Reports 15, 621 (2021). https://doi.org/10.1186/s13256-021-03193-
Age Appropriate Wisdom? Ethnobiological Knowledge Ontogeny in Pastoralist Mexican Choyeros
We investigate whether age profiles of ethnobiological knowledge development are consistent with predictions derived from life history theory about the timing of productivity and reproduction. Life history models predict complementary knowledge profiles developing across the lifespan for women and men as they experience changes in embodied capital and the needs of dependent offspring. We evaluate these predictions using an ethnobiological knowledge assessment tool developed for an off-grid pastoralist population, known as Choyeros, from Baja California Sur, Mexico. Our results indicate that while individuals acquire knowledge of most dangerous items and edible resources by early adulthood, knowledge of plants and animals relevant to the age and sex divided labor domains and ecologies (e.g., women’s house gardens, men’s herding activities in the wilderness) continues to develop into middle adulthood but to different degrees and at different rates for men and women. As the demands of offspring accumulate for parents with age, reproductive aged adults continue to develop their knowledge to meet their children’s needs. After controlling for vision, post-reproductive adults’ show the greatest ethnobiological knowledge. These findings extend our understanding of the evolved human life history by illustrating how changes in embodied capital and the needs of dependent offspring predict the development of men’s and women’s ethnobiological knowledge across the lifespan
Biologia de Centris Fabricius (Hymenoptera, Anthophoridae, Centridini) em matas contĂnuas e fragmentos na AmazĂ´nia Central.
TĂtulo em InglĂŞs: Biology of Centris Fabricius (Hymenoptera, Anthophoridae, Centridini) in continuous forest and fragments in Central Amazonia
Spontaneous R-Parity violation bounds
We investigate bounds from tree-level and one-loop processes in generic
supersymmetric models with spontaneous R-parity breaking in the superpotential.
We analyse the bounds from a general point of view. The bounds are applicable
both for all models with spontaneous R-parity violation and for explicit
bilinear R-parity violation based on general lepton-chargino and
neutrino-neutralino mixings. We find constraints from semileptonic B, D and K
decays, leptonic decays of the mu and tau, electric dipole moments, as well as
bounds for the anomalous magnetic moment of the muon.Comment: 22 page
Post-Inflationary Reheating
We study a model for reheating that has been much investigated for parametric
resonance, having a quartic interaction of the scalar inflaton with another
scalar field. Attention is particularly on the quantum excitations of the
inflaton field and the metric perturbation with a smooth transition from
quantum to classical stochastic states, followed through from a specific
inflation model to a state including a relativistic fluid. The scalar fields
enter non-perturbatively but the metric enters perturbatively, and the validity
of this latter is assessed. In this model our work seems to point the large
scale curvature parameter changing.Comment: 25 pages, 6 figures. Coding error(misprint) corrected:figures and
some conclusions change
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