46 research outputs found

    Incidence of and socio-biologic risk factors for spontaneous preterm birth in HIV positive Nigerian women

    Get PDF
    BACKGROUND: Recent studies have identified HIV as a leading contributor to preterm delivery and its associated morbidity and mortality. However little or no information exists in our sub-region on this subject. Identifying the factors associated with preterm delivery in HIV positive women in our country and sub-region will not only prevent mother to child transmission of HIV virus but will also reduce the morbidity and mortality associated with prematurity and low birth weight. This study was designed to determine the incidence and risk factors for preterm delivery in HIV positive Nigerians. METHOD: The required data for this retrospective study was extracted from the data base of a cohort study of the outcome of prevention of mother to child transmission at the Nigerian Institute of Medical Research, Lagos. Only data of women that met the eligibility of spontaneous delivery after 20 weeks of gestation were included. Ethical approval was obtained from the Institution’s Ethical Review Board. RESULTS: 181 women out of the 1626 eligible for inclusion into the study had spontaneous preterm delivery (11.1%). The mean birth weight was 3.1 ± 0.4 kg, with 10.3% having LBW. Spontaneous preterm delivery was found to be significantly associated with unmarried status (cOR: 1.7;1.52-2.57), baseline CD4 count <200 cells/mm(3)(cOR: 1.8; 1.16-2.99), presence of opportunistic infection at delivery (cOR: 2.2;1.23-3.57), multiple pregnancy (cOR 10.4; 4.24 – 26.17), use of PI based triple ARV therapy (eOR 10.2; 5.52 – 18.8) in the first trimester (cOR 2.5; 1.77 – 3.52) on univariate analysis. However after multivariate analysis controlling for potential confounding variables including low birth weight, only multiple pregnancy (aOR: 8.6; CI: 6.73 – 12.9), presence of opportunistic infection at delivery (aOR: 1.9; CI: 1.1 – 5.7), and 1st trimester exposure to PI based triple therapy (aOR: 5.4; CI: 3.4 – 7.8) retained their significant association with preterm delivery. CONCLUSION: The spontaneous preterm delivery rate among our cohort was 11.1%. HIV positive women with multiple pregnancies, symptomatic HIV infection at delivery and first trimester fetal exposure to PI based triple therapy were found to be at risk of spontaneous preterm delivery. Early booking and non-use of PI based triple therapy in the first trimester will significantly reduce the risk of preterm delivery

    Measurement of scintillation response of CsI[Na] to low-energy nuclear recoils by COHERENT

    Full text link
    We present results of several measurements of CsI[Na] scintillation response to 3-60 keV energy nuclear recoils performed by the COHERENT collaboration using tagged neutron elastic scattering experiments and an endpoint technique. Earlier results, used to estimate the coherent elastic neutrino-nucleus scattering (CEvNS) event rate for the first observation of this process achieved by COHERENT at the Spallation Neutron Source (SNS), have been reassessed. We discuss corrections for the identified systematic effects and update the respective uncertainty values. The impact of updated results on future precision tests of CEvNS is estimated. We scrutinize potential systematic effects that could affect each measurement. In particular we confirm the response of the H11934-200 Hamamatsu photomultiplier tube (PMT) used for the measurements presented in this study to be linear in the relevant signal scale region.Comment: The version accepted by JINST. The changes made as a result of the peer review process: 1. Section 8 "Global CsI[Na] QF data fit" is expanded. The main fit result and its uncertainty is NOT CHANGED. An alternative fit is now shown in Figure 14, Figure 15 is added to further validate the assumptions in the main fit. 2. The Appendix B is restructured for clarit

    Measurement of nat{}^{nat}Pb(νe\nu_e,Xnn) production with a stopped-pion neutrino source

    Full text link
    Using neutrinos produced at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), the COHERENT collaboration has studied the Pb(νe\nu_e,Xnn) process with a lead neutrino-induced-neutron (NIN) detector. Data from this detector are fit jointly with previously collected COHERENT data on this process. A combined analysis of the two datasets yields a cross section that is 0.290.16+0.170.29^{+0.17}_{-0.16} times that predicted by the MARLEY event generator using experimentally-measured Gamow-Teller strength distributions, consistent with no NIN events at 1.8σ\sigma. This is the first inelastic neutrino-nucleus process COHERENT has studied, among several planned exploiting the high flux of low-energy neutrinos produced at the SNS.Comment: 11 pages, 9 figures, version accepted by Phys. Rev.

    Monitoring the SNS basement neutron background with the MARS detector

    Full text link
    We present the analysis and results of the first dataset collected with the MARS neutron detector deployed at the Oak Ridge National Laboratory Spallation Neutron Source (SNS) for the purpose of monitoring and characterizing the beam-related neutron (BRN) background for the COHERENT collaboration. MARS was positioned next to the COH-CsI coherent elastic neutrino-nucleus scattering detector in the SNS basement corridor. This is the basement location of closest proximity to the SNS target and thus, of highest neutrino flux, but it is also well shielded from the BRN flux by infill concrete and gravel. These data show the detector registered roughly one BRN per day. Using MARS' measured detection efficiency, the incoming BRN flux is estimated to be 1.20 ± 0.56 neutrons/m2/MWh1.20~\pm~0.56~\text{neutrons}/\text{m}^2/\text{MWh} for neutron energies above 3.5\sim3.5~MeV and up to a few tens of MeV. We compare our results with previous BRN measurements in the SNS basement corridor reported by other neutron detectors.Comment: Submitted to JINS

    COHERENT Collaboration data release from the measurements of CsI[Na] response to nuclear recoils

    Full text link
    Description of the data release 10.13139/OLCF/1969085 (https://doi.ccs.ornl.gov/ui/doi/426) from the measurements of the CsI[Na] response to low energy nuclear recoils by the COHERENT collaboration. The release corresponds to the results published in "D. Akimov et al 2022 JINST 17 P10034". We share the data in the form of raw ADC waveforms, provide benchmark values, and share plots to enhance the transparency and reproducibility of our results. This document describes the contents of the data release as well as guidance on the use of the data

    First Probe of Sub-GeV Dark Matter Beyond the Cosmological Expectation with the COHERENT CsI Detector at the SNS

    Full text link
    The COHERENT collaboration searched for scalar dark matter particles produced at the Spallation Neutron Source with masses between 1 and 220~MeV/c2^2 using a CsI[Na] scintillation detector sensitive to nuclear recoils above 9~keVnr_\text{nr}. No evidence for dark matter is found and we thus place limits on allowed parameter space. With this low-threshold detector, we are sensitive to coherent elastic scattering between dark matter and nuclei. The cross section for this process is orders of magnitude higher than for other processes historically used for accelerator-based direct-detection searches so that our small, 14.6~kg detector significantly improves on past constraints. At peak sensitivity, we reject the flux consistent with the cosmologically observed dark-matter concentration for all coupling constants αD<0.64\alpha_D<0.64, assuming a scalar dark-matter particle. We also calculate the sensitivity of future COHERENT detectors to dark-matter signals which will ambitiously test multiple dark-matter spin scenarios
    corecore