471 research outputs found

    Anthropogenic impacts on mosquito populations in North America over the past century.

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    The recent emergence and spread of vector-borne viruses including Zika, chikungunya and dengue has raised concerns that climate change may cause mosquito vectors of these diseases to expand into more temperate regions. However, the long-term impact of other anthropogenic factors on mosquito abundance and distributions is less studied. Here, we show that anthropogenic chemical use (DDT; dichlorodiphenyltrichloroethane) and increasing urbanization were the strongest drivers of changes in mosquito populations over the last eight decades in areas on both coasts of North America. Mosquito populations have increased as much as tenfold, and mosquito communities have become two- to fourfold richer over the last five decades. These increases are correlated with the decay in residual environmental DDT concentrations and growing human populations, but not with temperature. These results illustrate the far-reaching impacts of multiple anthropogenic disturbances on animal communities and suggest that interactions between land use and chemical use may have unforeseen consequences on ecosystems

    Does e-learning policy drive change in Higher Education?: A case study relating models of organisational change to e-learning implementation

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    Due to the heightened competition introduced by the potential global market and the need for structural changes within organisations delivering e-content, e-learning policy is beginning to take on a more significant role within the context of educational policy per se. For this reason, it is becoming increasingly important to establish what effect such policies have and how they are achieved. This paper addresses this question, illustrating five ways in which change is understood (Fordist, evolutionary, ecological, community of practice and discourse-oriented) and then using this range of perspectives to explore how e-learning policy drives change (both organisational and pedagogic) within a selected higher education institution. The implications of this case are then discussed, and both methodological and pragmatic conclusions are drawn, considering the relative insights offered by the models and ways in which change around e-learning might be supported or promoted

    The relationship between talin and acetylcholine receptor clusters in Xenopus muscle cells

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    La fonction de la taline dans les jonctions neuro-musculaires est inconnue. On examine sa distribution dans les groupements de rĂ©cepteurs Ă  l'acĂ©tylcholine (AChR) matures et en dĂ©veloppement dans les cellules musculaires de Xenopus, in vivo et in vitro, par immunofluorescence. La taline y est prĂ©sente de maniĂšre variable, ce qui suggĂšre qu'elle n'est pas impliquĂ©e dans l'entretien des groupements mais pourrait ĂȘtre impliquĂ©e dans l'assemblage des structures spĂ©cialisĂ©es prĂ©sentes dans les groupements d'AChR

    Predictors of Depression in Very Young Children: A Prospective Study

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    There have been only a few previous population-based studies of symptoms of depression in young children. There are no previous population-based studies which examine the factors which might be casually associated with depression in very young children

    Operationalising learning from rare events: framework for middle humanitarian operations managers

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    The purpose of this paper is to investigate the learning from rare events and the knowledge management processinvolved, which presents a significant challenge to many organizations. This is primarily attributed to the inability tointerpret these events in a systematic and “rich” manner, which this paper seeks to address. We start by summarizing therelevant literature on humanitarian operations management (HOM), outlining the evolution of the socio-technical disasterlifecycle and its relationship with humanitarian operations, using a supply chain resilience theoretical lens. We then out-line theories of organizational learning (and unlearning) from disasters and the impact on humanitarian operations. Subse-quently, we theorize the role of middle managers in humanitarian operations, which is the main focus of our paper. Themain methodology incorporates a hybrid of two techniques for root cause analysis, applied to two related case studies.The cases were specifically selected as, despite occurring twenty years apart, there are many similarities in the chain ofcausation and supporting factors, potentially suggesting that adequate learning from experience and failures is not occur-ring. This provides a novel learning experience within the HOM paradigm. Hence, the proposed approach is based on amultilevel structure that facilitates the operationalization of learning from rare events in humanitarian operations. Theresults show that we are able to provide an environment for multiple interpretations and effective learning, with emphasison middle managers within a humanitarian operations and crisis/disaster management context

    The Role of Hydrogeography and Climate in the Landscape Epidemiology of West Nile Virus in New York State from 2000 to 2010

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    The epidemiology and ecology of West Nile virus (WNV) have not yet been completely described. In particular, the specific roles of climate and water in the landscape in the occurrence of human WNV cases remain unknown. This study used Poisson regression to describe the relationships between WNV cases and temperature, precipitation, and the hydrogeography of the landscape in New York State from 2000 to 2010. Fully adjusted models showed that hydrogeographic area was significantly inversely associated with WNV cases (incidence rate ratio (IRR) = 0.99; 95% C.I. = 0.98–0.997, p = 0.04), such that each one square kilometer increase in hydrogeographic area was associated with a 1% decrease in WNV incidence. This association was independent of both temperature, which was also associated with WNV incidence (IRR = 2.06; 95% C.I. = 1.84–2.31, p<0.001), and precipitation, which was not (IRR = 1.0; 95% C.I. = 0.99–1.01, p = 0.16). While the results are only suggestive due to the county-level aggregated data, these findings do identify a potentially important surveillance signal in the landscape epidemiology of WNV infection

    Human and Organizational Issues for Resilient Communications

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    Human and organizational issues are able to create both vulnerabilities and resilience to threats. In this chapter, we investigate human and organizational factors, conducted through ethnographic studies of operators and sets of interviews with staff responsible for security, reliability and quality in two different organizations, which own and operate utility networks. Ethnography is a qualitative orientation to research that emphasizes the detailed observation and interview of people in naturally occurring settings. Our findings indicate that 'human error' forms the biggest threat to cyber-security and that there is a need for Security Operational Centres to document all cyber-security accidents. Also, we conclude that it will always be insufficient to assess mental security models in terms of their technical correctness, as it is sometimes more important to know how well they represent prevailing social issues and requirements. As a practical recommendation from this work, we suggest that utility organizations engage in penetration testing and perhaps other forms of vulnerability analysis, not only to discover specific vulnerabilities but also to learn more about the mental models they use

    A proposed framework for the development and qualitative evaluation of West Nile virus models and their application to local public health decision-making

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    West Nile virus(WNV) is a globally distributed mosquito-borne virus of great public health concern. The number of WNV human cases and mosquito infection patterns vary in space and time. Many statistical models have been developed to understand and predict WNV geographic and temporal dynamics. However, these modeling efforts have been disjointed with little model comparison and inconsistent validation. In this paper, we describe a framework to unify and standardize WNV modeling efforts nationwide. WNV risk, detection, or warning models for this review were solicited from active research groups working in different regions of the United States. A total of 13 models were selected and described. The spatial and temporal scales of each model were compared to guide the timing and the locations for mosquito and virus surveillance, to support mosquito vector control decisions, and to assist in conducting public health outreach campaigns at multiple scales of decision-making. Our overarching goal is to bridge the existing gap between model development, which is usually conducted as an academic exercise, and practical model applications, which occur at state, tribal, local, or territorial public health and mosquito control agency levels. The proposed model assessment and comparison framework helps clarify the value of individual models for decision-making and identifies the appropriate temporal and spatial scope of each model. This qualitative evaluation clearly identifies gaps in linking models to applied decisions and sets the stage for a quantitative comparison of models. Specifically, whereas many coarse-grained models (county resolution or greater) have been developed, the greatest need is for fine-grained, short-term planning models (m–km, days–weeks) that remain scarce. We further recommend quantifying the value of information for each decision to identify decisions that would benefit most from model input

    Actin waves do not boost neurite outgrowth in the early stages of neuron maturation

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    During neurite development, Actin Waves (AWs) emerge at the neurite base and move up to its tip, causing a transient retraction of the Growth Cone (GC). Many studies have shown that AWs are linked to outbursts of neurite growth and, therefore, contribute to the fast elongation of the nascent axon. Using long term live cell-imaging, we show that AWs do not boost neurite outgrowth and that neurites without AWs can elongate for several hundred microns. Inhibition of Myosin II abolishes the transient GC retraction and strongly modifies the AWs morphology. Super-resolution nanoscopy shows that Myosin IIB shapes the growth cone-like AWs structure and is differently distributed in AWs and GCs. Interestingly, depletion of membrane cholesterol and inhibition of Rho GTPases decrease AWs frequency and velocity. Our results indicate that Myosin IIB, membrane tension, and small Rho GTPases are important players in the regulation of the AW dynamics. Finally, we suggest a role for AWs in maintaining the GCs active during environmental exploration
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