259 research outputs found

    Association of ABO blood groups with Chikungunya virus

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    Chikungunya virus (CHIKV) an emerging arboviral infection of public health concern belongs to the genus Alphavirus, family Togaviridae. Blood group antigens are generally known to act as receptors for various etiological agents. The studies defining the relationship between blood groups and CHIKV is limited and hence it is necessary to study these parameters in detail. In the present study 1500 subjects were enrolled and demographic data (Age, Gender, Blood group, CHIKV infection status, and CHIKV infection confirmation mode) was collected from them. The risk of acquiring CHIKV disease and its association with factors such as blood group, age and gender was analyzed statistically. The data of this study showed a possible association between blood group, age and gender of the study population with CHIKV infection. It is observed that CHIKV infections were higher in individuals with Rh positive blood group when compared to their Rh negative counterparts.CHIKV infections were found to be higher in Rh positive individuals of AB and A blood groups than that of Rh negative counterparts. Results also indicated that infections were higher in adults belonging to the age group > 30 years and also higher in males as compared to females enrolled in this study. These data present further evidence for the association of the blood groups, age and gender to susceptibility to CHIKV infection. Further studies are needed to confirm these findings. This is the second study showing the possible association of blood groups with chikungunya

    Rooting depth explains [CO <inf>2</inf>]× drought interaction in Eucalyptus saligna

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    Elevated atmospheric [CO 2] (eCa) often decreases stomatal conductance, which may delay the start of drought, as well as alleviate the effect of dry soil on plant water use and carbon uptake. We studied the interaction between drought and eCa in a whole-tree chamber experiment with Eucalyptus saligna. Trees were grown for 18 months in their Ca treatments before a 4-month dry-down. Trees grown in eCa were smaller than those grown in ambient Ca (aCa) due to an early growth setback that was maintained throughout the duration of the experiment. Pre-dawn leaf water potentials were not different between Ca treatments, but were lower in the drought treatment than the irrigated control. Counter to expectations, the drought treatment caused a larger reduction in canopy-average transpiration rates for trees in the eCa treatment compared with aCa. Total tree transpiration over the dry-down was positively correlated with the decrease in soil water storage, measured in the top 1.5 m, over the drying cycle; however, we could not close the water budget especially for the larger trees, suggesting soil water uptake below 1.5 m depth. Using neutron probe soil water measurements, we estimated fractional water uptake to a depth of 4.5 m and found that larger trees were able to extract more water from deep soil layers. These results highlight the interaction between rooting depth and response of tree water use to drought. The responses of tree water use to eCa involve interactions between tree size, root distribution and soil moisture availability that may override the expected direct effects of eCa. It is essential that these interactions be considered when interpreting experimental results. © 2011 The Author. Published by Oxford University Press. A ll rights reserved

    The peaked response of transpiration rate to vapour pressure deficit in field conditions can be explained by the temperature optimum of photosynthesis

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    Leaf transpiration rate (E) frequently shows a peaked response to increasing vapour pressure deficit (D). The mechanisms for the decrease in E at high D, known as the 'apparent feed-forward response', are strongly debated but explanations to date have exclusively focused on hydraulic processes. However, stomata also respond to signals related to photosynthesis. We investigated whether the apparent feed-forward response of E to D in the field can be explained by the response of photosynthesis to temperature (T), which normally co-varies with D in field conditions. As photosynthesis decreases with increasing T past its optimum, it may drive a decrease in stomatal conductance (gs) that is additional to the response of gs to increasing D alone. If this additional decrease is sufficiently steep and coupling between A and gs occurs, it could cause an overall decrease in E with increasing D. We tested this mechanism using a gas exchange model applied to leaf-scale and whole-tree CO2 and H2O fluxes measured on Eucalyptus saligna growing in whole-tree chambers. A peaked response of E to D was observed at both leaf and whole-tree scales. We found that this peaked response was matched by a gas exchange model only when T effects on photosynthesis were incorporated. We conclude that field-based studies of the relationship between E and D need to consider signals related to changing photosynthetic rates in addition to purely hydraulic mechanisms. © 2014 Elsevier B.V

    smt: a Matlab structured matrices toolbox

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    We introduce the smt toolbox for Matlab. It implements optimized storage and fast arithmetics for circulant and Toeplitz matrices, and is intended to be transparent to the user and easily extensible. It also provides a set of test matrices, computation of circulant preconditioners, and two fast algorithms for Toeplitz linear systems.Comment: 19 pages, 1 figure, 1 typo corrected in the abstrac

    Seasonal variation in airborne infection risk in schools due to changes in ventilation inferred from monitored carbon dioxide

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    The year 2020 has seen the world gripped by the effects of the COVID-19 pandemic. It is not the first time, nor will it be last, that our increasingly globalized world has been significantly affected by the emergence of a new disease. In much of the Northern Hemisphere, the academic year begins in September, and for many countries, September 2020 marked the return to full schooling after some period of enforced closure due to COVID-19. In this paper, we focus on the airborne spread of disease and investigate the likelihood of transmission in school environments. It is crucial to understand the risk airborne infection from COVID-19 might pose to pupils, teachers, and their wider social groups. We use monitored CO2 data from 45 classrooms in 11 different schools from within the UK to estimate the likelihood of infection occurring within classrooms regularly attended by the same staff and pupils. We determine estimates of the number of secondary infections arising via the airborne route over pre/asymptomatic periods on a rolling basis. Results show that, assuming relatively quiet desk-based work, the number of secondary infections is likely to remain reassuringly below unity; however, it can vary widely between classrooms of the same school even when the same ventilation system is present. Crucially, the data highlight significant variation with the seasons with January being nearly twice as risky as July. We show that such seasonal variations in risk due to changes in ventilation rates are robust and our results hold for wide variations in disease parameterizations, suggesting our results may be applied to a number of different airborne diseases

    Reconciling the optimal and empirical approaches to modelling stomatal conductance

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    Models of vegetation function are widely used to predict the effects of climate change on carbon, water and nutrient cycles of terrestrial ecosystems, and their feedbacks to climate. Stomatal conductance, the process that governs plant water use and carbon uptake, is fundamental to such models. In this paper, we reconcile two long-standing theories of stomatal conductance. The empirical approach, which is most commonly used in vegetation models, is phenomenological, based on experimental observations of stomatal behaviour in response to environmental conditions. The optimal approach is based on the theoretical argument that stomata should act to minimize the amount of water used per unit carbon gained. We reconcile these two approaches by showing that the theory of optimal stomatal conductance can be used to derive a model of stomatal conductance that is closely analogous to the empirical models. Consequently, we obtain a unified stomatal model which has a similar form to existing empirical models, but which now provides a theoretical interpretation for model parameter values. The key model parameter, g1, is predicted to increase with growth temperature and with the marginal water cost of carbon gain. The new model is fitted to a range of datasets ranging from tropical to boreal trees. The parameter g1 is shown to vary with growth temperature, as predicted, and also with plant functional type. The model is shown to correctly capture responses of stomatal conductance to changing atmospheric CO2, and thus can be used to test for stomatal acclimation to elevated CO2. The reconciliation of the optimal and empirical approaches to modelling stomatal conductance is important for global change biology because it provides a simple theoretical framework for analyzing, and simulating, the coupling between carbon and water cycles under environmental change. © 2011 Blackwell Publishing Ltd

    Interactive effects of elevated CO <inf>2</inf> and drought on nocturnal water fluxes in Eucalyptus saligna

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    Nocturnal water flux has been observed in trees under a variety of environmental conditions and can be a significant contributor to diel canopy water flux. Elevated atmospheric CO 2 (elevated [CO 2]) can have an important effect on day-time plant water fluxes, but it is not known whether it also affects nocturnal water fluxes. We examined the effects of elevated [CO 2] on nocturnal water flux of field-grown Eucalyptus saligna trees using sap flux through the tree stem expressed on a sapwood area (J s) and leaf area (E t) basis. After 19 months growth under well-watered conditions, drought was imposed by withholding water for 5 months in the summer, ending with a rain event that restored soil moisture. Reductions in J s and E t were observed during the severe drought period in the dry treatment under elevated [CO 2], but not during moderate- and post-drought periods. Elevated [CO 2] affected night-time sap flux density which included the stem recharge period, called 'total night flux' (19:00 to 05:00, J s,r), but not during the post-recharge period, which primarily consisted of canopy transpiration (23:00 to 05:00, J s,c). Elevated [CO 2] wet (EW) trees exhibited higher J s,r than ambient [CO 2] wet trees (AW) indicating greater water flux in elevated [CO 2] under well-watered conditions. However, under drought conditions, elevated [CO 2] dry (ED) trees exhibited significantly lower J s,r than ambient [CO 2] dry trees (AD), indicating less water flux during stem recharge under elevated [CO 2]. J s,c did not differ between ambient and elevated [CO 2]. Vapour pressure deficit (D) was clearly the major influence on night-time sap flux. D was positively correlated with J s,r and had its greatest impact on J s,r at high D in ambient [CO 2]. Our results suggest that elevated [CO 2] may reduce night-time water flux in E. saligna when soil water content is low and D is high. While elevated [CO 2] affected J s,r, it did not affect day-time water flux in wet soil, suggesting that the responses of J s,r to environmental factors cannot be directly inferred from day-time patterns. Changes in J s,r are likely to influence pre-dawn leaf water potential, and plant responses to water stress. Nocturnal fluxes are clearly important for predicting effects of climate change on forest physiology and hydrology. © 2011 The Author. Published by Oxford University Press. A ll rights reserved

    Whole-tree chambers for elevated atmospheric CO<inf>2</inf> experimentation and tree scale flux measurements in south-eastern Australia: The Hawkesbury Forest Experiment

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    Resolving ecophysiological processes in elevated atmospheric CO2 (Ca) at scales larger than single leaves poses significant challenges. Here, we describe a field-based experimental system designed to grow trees up to 9m tall in elevated Ca with the capacity to control air temperature and simultaneously measure whole-tree gas exchange. In western Sydney, Australia, we established the Hawkesbury Forest Experiment (HFE) where we built whole-tree chambers (WTC) to measure whole-tree CO2 and water fluxes of an evergreen broadleaf tree, Eucalyptus saligna. A single E. saligna tree was grown from seedling to small tree within each of 12 WTCs; six WTCs were maintained at ambient Ca and six WTCs were maintained at elevated Ca, targeted at ambient Ca +240μmolmol-1. All 12 WTCs were controlled to track ambient outside air temperature (Tair) and air water vapour deficit (Dair). During the experimental period, Tair, Dair and Ca in the WTCs were within 0.5°C, 0.3kPa, and 15μmolmol-1 of the set-points for 90% of the time, respectively. Diurnal responses of whole-tree CO2 and water vapour fluxes are analysed, demonstrating the ability of the tree chamber system to measure rapid environmental responses of these fluxes of entire trees. The light response of CO2 uptake for entire trees showed a clear diurnal hysteresis, attributed to stomatal closure at high Dair. Tree scale CO2 fluxes confirm the hypothesised deleterious effect of chilling night-time temperatures on whole-tree carbon gain in this subtropical Eucalyptus. The whole-tree chamber flux data add an invaluable scale to measurements in both ambient and elevated Ca and allow us to elucidate the mechanisms driving tree productivity responses to elevated Ca in interaction with water availability and temperature. © 2010 Elsevier B.V

    Sistema de controle e de informações gerenciais

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    O Sistema de Controle de Informações Gerenciais foi planejado com o intuito de otimizar o planejamento das ações da Comissão de Valores Imobiliários e, paralelamente, melhorar os serviços por ela prestados. O sistema possui dois enfoques gerenciais. O primeiro é consubstanciado por meio de um Relatório de Informações Econômico-Financeiras, e o segundo é representado pelo Sistema de Cobrança das Multas Cominatórias. Os relatórios retratam a execução orçamentária, o processo de arrecadação, as despesas e os processos de compras, o domínio e o controle dos dados, com vistas ao planejamento, à tomada de decisões e à fixação de metas e prioridades. As informações constantes dos documentos são públicas e podem ser consultadas por quaisquer servidores da CVM e pelas entidades de classeNúmero de páginas: 1 p.InovaçãoIniciativa premiada no 2º Concurso Inovação na Gestão Pública Federal sob responsabilidade de Miguel Antonio Bahury Júnior. Ações premiadas no 2º Concurso Inovação na Gestão Pública Federal – 1997. Área temática: gestão da informaçã
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