3,429 research outputs found

    MAGIC sensitivity to millisecond-duration optical pulses

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    The MAGIC telescopes are a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs) designed to observe very high energy (VHE) gamma rays above ~50 GeV. However, as IACTs are sensitive to Cherenkov light in the UV/blue and use photo-detectors with a time response well below the ms scale, MAGIC is also able to perform simultaneous optical observations. Through an alternative system installed in the central PMT of MAGIC II camera, the so-called central pixel, MAGIC is sensitive to short (1ms - 1s) optical pulses. Periodic signals from the Crab pulsar are regularly monitored. Here we report for the first time the experimental determination of the sensitivity of the central pixel to isolated 1-10 ms long optical pulses. The result of this study is relevant for searches of fast transients such as Fast Radio Bursts (FRBs).Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Bexco, Busan, Korea (arXiv:1708.05153

    Social and situational dynamics surrounding workplace mistreatment: Context matters

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163449/2/job2479_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163449/1/job2479.pd

    Estudio del comportamiento de pinturas acrílicas sobre tablero contrachapado tras envejecimiento artificial

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    Entre los soportes más empleados en arte contemporáneo se encuentran los tableros derivados de la madera. Hasta el momento, las investigaciones para determinar la influencia de un soporte de tablero contrachapado en capas pictóricas acrílicas así como las condiciones óptimas para su conservación, resultan insuficientes o completamente ausentes. En la elaboración de estos tableros se utilizan adhesivos para darles consistencia pero la influencia de estos adhesivos en las capas pictóricas artísticas estará en función del tipo de tablero, del tipo de adhesivo empleado, de las condiciones ambientales y de las características de las capas pictóricas. Es evidente pues, la necesidad de modelos comparativos. Por todos estos motivos, el objetivo principal de esta investigación ha sido comprender la transformación que experimentan estos materiales durante su envejecimiento y las causas que pueden desestabilizar las obras, con el fin de adoptar las medidas necesarias para evitar un envejecimiento prematuro. Mediantela Espectroscopía Infrarroja por Transformada de Fourier FTIR se han analizado los cambios sufridos por modelos experimentales realizados con pinturas acrílicas imprimidas sobre tablero contrachapado trasser sometidos a ciclos de envejecimiento por choquetérmico (Cold-check test) y envejecimiento en condiciones de alta humedad

    Maternal Risk Factors for Small-for-Gestational-Age Newborns in Mexico: Analysis of a Nationwide Representative Cohort

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    Background: Small for gestational age (SGA) is a key contributor to premature deaths and long-term complications in life. Improved characterization of maternal risk factors associated with this adverse outcome is needed to inform the development of interventions, track progress, and reduce the disease burden. This study aimed to identify socioeconomic, demographic, and clinical factors associated with SGA in Mexico. Methods: We analyzed administrative data from 1,841,477 singletons collected by the National Information Subsystem of Livebirths during 2017. Small-for-gestational-age was defined as being 12 years (aOR 0.63; 95% CI:0.6,0.66) compared with those without education. SGA was particularly likely to occur among primiparous (aOR 1.42; 95% CI: 1.39, 1.43), mothers living in very high deprivation localities (aOR 1.39; 95% CI: 1.36, 1.43), young (aOR 1.04; 95% CI: 1.02, 1.06), advanced age (aOR 1.14; 95% CI 1.09, 1.19), and mothers living in areas above 2,000 m (aOR 1.69; 95% CI: 1.65, 1.73). Antenatal care was associated with a reduced risk of SGA by 30% (aOR 0.7; 95% CI:0.67,0.73), 23% (OR 0.77; 95% CI:0.74,0.8), and 21% (OR 0.79; 95% CI:0.75,0.83), compared with those mothers who never received antenatal care, when women visited the clinic at the first, second and third trimester, respectively. Conclusion: Almost 7% of live births were found to be SGA. Parity, maternal age, education, place of residence, and social deprivation were significantly associated with this outcome. Antenatal care was protective. These findings imply that interventions focusing on early and adequate contact with health care facilities, reproductive health counseling, and maternal education should reduce SGA in Mexico

    Duration of the IgM response in women acquiring Toxoplasma gondii during pregnancy: implications for clinical practice and cross-sectional incidence studies

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    We followed up a cohort of 446 toxoplasma-infected pregnant women to determine the median and variability of the duration of positive toxoplasma-IgM (immunoglobulin M) results measured by an immunofluorescence test (IFT) and an immunosorbent agglutination assay (ISAGA). IgM antibodies were detected for longer using the ISAGA test [median 12(.)8 months, interquartile range (IQR) 6(.)9-24(.)9] than the IFT (median 10(.)4, IQR 7(.)1-14(.)4), but the variability between individuals in the duration of IgM positivity was greatest for the ISAGA test. IgM-positive results persisted beyond 2 years in a substantial minority of women (27(.)1% ISAGA, 9(.)1% IFT). Variation in the duration of the IgM response measured by ISAGA and IFT limit their usefulness for predicting the timing of infection in pregnant women. However, measurement of IgM and IgG antibodies in a cross-sectional serosurvey offers an efficient method for estimating the incidence of toxoplasma infection

    Presentation for care and antenatal management of HIV in the United Kingdom:temporal trends and demographic variations, 2009-2014

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    OBJECTIVES: Despite very low rates of vertical transmission of HIV in the UK overall, rates are higher among women starting antenatal antiretroviral therapy (ART) late. We investigated the timing of key elements of the care of HIV‐positive pregnant women [antenatal care booking, HIV laboratory assessment (CD4 count and HIV viral load) and antenatal ART initiation], to assess whether clinical practice is changing in line with recommendations, and to investigate factors associated with delayed care. METHODS: We used the UK's National Study of HIV in Pregnancy and Childhood for 2009−2014. Data were analysed by fitting logistic regression and Cox proportional hazards models. RESULTS: A total of 5693 births were reported; 79.5% were in women diagnosed with HIV prior to that pregnancy. Median gestation at antenatal booking was 12.1 weeks [interquartile range (IQR) 10.0–15.6 weeks] and booking was significantly earlier during 2012–2014 vs. 2009–2011 (P < 0.001), although only in previously diagnosed women. Overall, 42.2% of pregnancies were booked late (≥ 13 gestational weeks). Among women not already on treatment, antenatal ART commenced at a median of 21.4 (IQR18.1–24.5) weeks and started significantly earlier in the most recent time period (P < 0.001). Compared with previously diagnosed women, those newly diagnosed during the current pregnancy booked later for antenatal care and started antenatal ART later (both P < 0.001). Multivariable analyses revealed demographic variations in access to or uptake of care, with groups including migrants and parous women initiating care later. CONCLUSIONS: Although women are accessing antenatal and HIV care earlier in pregnancy, some continue to face barriers to timely initiation of antenatal care and ART

    Neonatal mortality in NHS maternity units by timing and mode of birth: a retrospective linked cohort study

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    OBJECTIVES: To compare neonatal mortality in English hospitals by time of day and day of the week according to care pathway. DESIGN: Retrospective cohort linking birth registration, birth notification and hospital episode data. SETTING: National Health Service (NHS) hospitals in England. PARTICIPANTS: 6 054 536 liveborn singleton births from 2005 to 2014 in NHS maternity units in England. MAIN OUTCOME MEASURES: Neonatal mortality. RESULTS: After adjustment for confounders, there was no significant difference in the odds of neonatal mortality attributed to asphyxia, anoxia or trauma outside of working hours compared with working hours for spontaneous births or instrumental births. Stratification of emergency caesareans by onset of labour showed no difference in mortality by birth timing for emergency caesareans with spontaneous or induced onset of labour. Higher odds of neonatal mortality attributed to asphyxia, anoxia or trauma out of hours for emergency caesareans without labour translated to a small absolute difference in mortality risk. CONCLUSIONS: The apparent 'weekend effect' may result from deaths among the relatively small numbers of babies who were coded as born by emergency caesarean section without labour outside normal working hours. Further research should investigate the potential contribution of care-seeking and community-based factors as well as the adequacy of staffing for managing these relatively unusual emergencies
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