8,647 research outputs found

    Discrete time series generated by mixtures I: Correlational and runs properties

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    A broad but parametrically simple model for a stationary sequence of dependent discrete random variables is given and several submodels are discussed. The structure of the model is specified by the marginal distribution of the random variables and several other parameters. The sequence of random variables is formed by a probabilistic linear combination of independent, identically distributed discrete random variables and is in general not Markovian. Second-order joint moments and spectra are obtained for the model, as well as some properties for the lengths of runs. The special case of process in which the variables take on only two values is useful as a model for the counting process in a discrete-time point process. An application to the modelling of erros in the transmission of binary data is briefly discussed. (Author)supported by funds provided directly from the Chief of Naval Research under Grant NR-42-284, and the National Science Foundation under Grant NSF-75-02026http://archive.org/details/discretetimeseri00lewiN

    The effects of early years' childcare on child emotional and behavioural difficulties in lone and co-parent family situations

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    With targeted childcare initiatives and welfare-to-work programmes policy-makers have sought to address employment activation of lone mothers and negative outcomes for children in lone parent households. The present study examines non-parental childcare use and maternal employment among children living in lone and co-parent family situations at ages three and four and emotional and behavioural difficulties at ages four and five. The results demonstrate that negative outcomes associated with lone motherhood are explained largely by mother's age, education, material circumstances and area deprivation; and that maternal employment does not relieve lone mothers’ disadvantages in a way that alleviates the risks of difficulties to their children. However, in any family constellation, mainly group-based formal pre-school childcare does have a positive impact on child difficulties compared to drawing on informal childcare arrangements as main provider. In addition, and specifically for the difficulties of children in lone mother family situations, any non-parental childcare – formal or informal − for at least twenty-five hours per week is beneficial. Study findings support policy agendas which tackle families’ material hardship beyond promoting mothers’ employment, and through investment in formal childcare provision, and also through arrangements allowing lone mothers to divide their weekly load of childcare with another main provider

    The origin of green icebergs in Antarctica

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    A comparison of samples from a translucent green iceberg with a core from the Ronne Ice Shelf revealed an excellent agreement in isotopic composition, crystal structure, and incorporated sediment particles. Marine shelf ice which constitutes the basal portion of some ice shelves is considered to be the source of green icebergs. It most likely results from "ice pump" processes which produce large amounts of ice platelets in the water column beneath ice shelves. These subsequently accumulate and become compacted into bubble-free, desalinated ice. Iceberg and drift-buoy trajectories indicate that green icebergs observed in the Weddell Sea originate from the Amery Ice Shelf rather than from the Ronne Ice Shelf, although the latter ice shelf is also a potential source

    Attack Rates Assessment of the 2009 Pandemic H1N1 Influenza A in Children and Their Contacts: A Systematic Review and Meta-Analysis

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    Background: The recent H1N1 influenza A pandemic was marked by multiple reports of illness and hospitalization in children, suggesting that children may have played a major role in the propagation of the virus. A comprehensive detailed analysis of the attack rates among children as compared with their contacts in various settings is of great importance for understanding their unique role in influenza pandemics. Methodology/Principal Findings: We searched MEDLINE (PubMed) and Embase for published studies reporting outbreak investigations with direct measurements of attack rates of the 2009 pandemic H1N1 influenza A among children, and quantified how these compare with those of their contacts. We identified 50 articles suitable for review, which reported school, household, travel and social events. The selected reports and our meta-analysis indicated that children had significantly higher attack rates as compared to adults, and that this phenomenon was observed for both virologically confirmed and clinical cases, in various settings and locations around the world. The review also provided insight into some characteristics of transmission between children and their contacts in the various settings. Conclusion/Significance: The consistently higher attack rates of the 2009 pandemic H1N1 influenza A among children, as compared to adults, as well as the magnitude of the difference is important for understanding the contribution of children to disease burden, for implementation of mitigation strategies directed towards children, as well as more precise mathematical modeling and simulation of future influenza pandemics

    The relationship between endogenous thymidine concentrations and [F-18]FLT uptake in a range of preclinical tumour models

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    BACKGROUND: Recent studies have shown that 3′-deoxy-3′-[18F] fluorothymidine ([18F]FLT)) uptake depends on endogenous tumour thymidine concentration. The purpose of this study was to investigate tumour thymidine concentrations and whether they correlated with [18F]FLT uptake across a broad spectrum of murine cancer models. A modified liquid chromatography-mass spectrometry (LC-MS/MS) method was used to determine endogenous thymidine concentrations in plasma and tissues of tumour-bearing and non-tumour bearing mice and rats. Thymidine concentrations were determined in 22 tumour models, including xenografts, syngeneic and spontaneous tumours, from six research centres, and a subset was compared for [18F]FLT uptake, described by the maximum and mean tumour-to-liver uptake ratio (TTL) and SUV. RESULTS: The LC-MS/MS method used to measure thymidine in plasma and tissue was modified to improve sensitivity and reproducibility. Thymidine concentrations determined in the plasma of 7 murine strains and one rat strain were between 0.61 ± 0.12 μM and 2.04 ± 0.64 μM, while the concentrations in 22 tumour models ranged from 0.54 ± 0.17 μM to 20.65 ± 3.65 μM. TTL at 60 min after [18F]FLT injection, determined in 14 of the 22 tumour models, ranged from 1.07 ± 0.16 to 5.22 ± 0.83 for the maximum and 0.67 ± 0.17 to 2.10 ± 0.18 for the mean uptake. TTL did not correlate with tumour thymidine concentrations. CONCLUSIONS: Endogenous tumour thymidine concentrations alone are not predictive of [18F]FLT uptake in murine cancer models

    Parental Substance Abuse As an Early Traumatic Event. Preliminary Findings on Neuropsychological and Personality Functioning in Young Drug Addicts Exposed to Drugs Early.

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    open5noParental substance use is a major risk factor for child development, heightening the risk of drug problems in adolescence and young adulthood, and exposing offspring to several types of traumatic events. First, prenatal drug exposure can be considered a form of trauma itself, with subtle but long-lasting sequelae at the neuro-behavioral level. Second, parents’ addiction often entails a childrearing environment characterized by poor parenting skills, disadvantaged contexts and adverse childhood experiences (ACEs), leading to dysfunctional outcomes. Young adults born from/raised by parents with drug problems and diagnosed with a Substance Used Disorder (SUD) themselves might display a particularly severe condition in terms of cognitive deficits and impaired personality function. This preliminary study aims to investigate the role of early exposure to drugs as a traumatic event, capable of affecting the psychological status of young drug addicts. In particular, it intends to examine the neuropsychological functioning and personality profile of young adults with severe SUDs who were exposed to drugs early in their family context. The research involved three groups, each consisting of 15 young adults (aged 18–24): a group of inpatients diagnosed with SUDs and exposed to drugs early, a comparison group of non-exposed inpatients and a group of non-exposed youth without SUDs. A neuropsychological battery (Esame Neuropsicologico Breve-2), an assessment procedure for personality disorders (Shedler-Westen Assessment Procedure-200) and the Symptom CheckList-90-Revised were administered. According to present preliminary results, young drug addicts exposed to drugs during their developmental age were characterized by elevated rates of neuropsychological impairments, especially at the expense of attentive and executive functions (EF); personality disorders were also common but did not differentiate them from non-exposed youth with SUDs. Alternative multi-focused prevention and intervention programs are needed for children of drug-misusing parents, addressing EF and adopting a trauma-focused approach.openParolin, Micol; Simonelli, Alessandra; Mapelli, Daniela; Sacco, M.; Cristofalo, P.Parolin, Micol; Simonelli, Alessandra; Mapelli, Daniela; Sacco, M.; Cristofalo, P

    Lactate signalling regulates fungal β-glucan masking and immune evasion

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    AJPB: This work was supported by the European Research Council (STRIFE, ERC- 2009-AdG-249793), The UK Medical Research Council (MR/M026663/1), the UK Biotechnology and Biological Research Council (BB/K017365/1), the Wellcome Trust (080088; 097377). ERB: This work was supported by the UK Biotechnology and Biological Research Council (BB/M014525/1). GMA: Supported by the CNPq-Brazil (Science without Borders fellowship 202976/2014-9). GDB: Wellcome Trust (102705). CAM: This work was supported by the UK Medical Research Council (G0400284). DMM: This work was supported by UK National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC/K000306/1). NARG/JW: Wellcome Trust (086827, 075470,101873) and Wellcome Trust Strategic Award in Medical Mycology and Fungal Immunology (097377). ALL: This work was supported by the MRC Centre for Medical Mycology and the University of Aberdeen (MR/N006364/1).Peer reviewedPostprin

    Markers of Inflammation, Coagulation, and Renal Function Are Elevated in Adults with HIV Infection

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    (See the article by Kalayjian et al, on pages 1796-1805, and the editorial commentary by Dubé and Sattler, on pages 1783-1785.) Background. Human immunodeficiency virus (HIV) replication and immune activation may increase inflammation and coagulation biomarkers. Limited data exist comparing such biomarkers in persons with and without HIV infection. Methods. For persons 45-76 years of age, levels of high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, D-dimer, and cystatin C were compared in 494 HIV-infected individuals in the Strategies for Management of Anti-Retroviral Therapy (SMART) study and 5386 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) study. For persons 33-44 years of age, hsCRP and IL-6 levels were compared in 287 participants in the SMART study and 3231 participants in the Coronary Artery Development in Young Adults (CARDIA) study. Results. hsCRP and IL-6 levels were 55% (P<.001) and 62% (P<.001) higher among HIV-infected participants than among CARDIA study participants. Compared with levels noted in MESA study participants, hsCRP, IL-6, D-dimer, and cystatin C levels were 50%, 152%, 94%, and 27% higher, respectively (P<.001 , for each), among HIV-infected participants. HIV-infected participants receiving antiretroviral therapy who had HIV RNA levels ≤400 copies/mL had levels higher (by 21% to 60%) (P<.001) than those in the general population, for all biomarkers. Conclusions. hsCRP, IL-6, D-dimer, and cystatin C levels are elevated in persons with HIV infection and remain so even after HIV RNA levels are suppressed with antiretroviral therapy. Additional research is needed on the pathophysiology of HIV-induced activation of inflammatory and coagulation pathways, to guide potential intervention

    SMART C: A Semantic Macro Replacement Translator for C

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    Programmers often want to transform the source or binary representations of their programs (e.g., to optimize, add dynamic safety checks, or add profile gathering code). Unfortunately, existing approaches to program transformation are either disruptive to the source (hand transformation), difficult to implement (ad hoc analysis tools), or functionally limited (macros). We propose an extension to the C programming language called the Semantic Macro Replacement Translator (SMART C). SMART C allows for the specification of very general type-aware transformations of all operations, statements, and declarations of the C programming language without exposing the programmer to the complexities of the system’s internal representations. We have implemented a prototype SMART C sourceto- source translator and show its use in transforming programs for buffer overflow detection, format string vulnerability detection, and weighted call graph profiling. We show that SMART C achieves a pragmatic balance between generality and ease of use

    Defining Functional Rural Areas

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    Functional Rural Areas describe central market towns and their hinterland. They allow for a better, i.e. more harmonised, comparison of socio-economic indicators. They are created as the rural counterpart of the Functional Urban Areas. Together they cover the entire territory. The methodology to create them is a draft, and feedback is warmly welcomed. This publication summarises the assumptions behind the delineation of Functional Rural Areas, and highlights some of the benefits of using them for statistical analysis.JRC.B.3 - Territorial Developmen
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