Abstract
Background
Previous studies are inconclusive concerning the association between maternal pre-pregnancy overweight/obesity and risk of attention-deficit/hyperactivity disorder (ADHD) in ...offspring. We therefore conducted a systematic review and meta-analysis to clarify this association. To address the variation in confounding adjustment between studies, especially inadequate adjustment of unmeasured familial confounding in most studies, we further performed cousin and sibling comparisons in a nationwide population-based cohort in Sweden.
Methods
We searched PubMed, Embase and PsycINFO during 1975–2018. We used random-effects models to calculate pooled risk ratios (RRs) with 95% confidence interval. In the population-based study, Cox proportional hazard models were used to calculate the unadjusted hazard ratios (HRs) and HRs adjusted for all confounders identified in previous studies. Stratified Cox models were applied to data on full cousins and full siblings to further control for unmeasured familial confounding.
Results
Eight cohorts with a total of 784 804 mother–child pairs were included in the meta-analysis. Maternal overweight RRoverweight = 1.31 (1.25–1.38), I2 = 6.80% and obesity RRobesity = 1.92 (1.84–2.00), I2 = 0.00% were both associated with an increased risk of ADHD in offspring. In the population-based cohort of 971 501 individuals born between 1992 and 2004, unadjusted Cox models revealed similar associations HRoverweight = 1.30 (1.28–1.34), HRobesity = 1.92 (1.87–1.98). These associations gradually attenuated towards the null when adjusted for measured confounders HRoverweight = 1.21 (1.19–1.25), HRobesity = 1.60 (1.55–1.65), unmeasured factors shared by cousins HRoverweight = 1.10 (0.98–1.23), HRobesity = 1.44 (1.22–1.70) and unmeasured factors shared by siblings HRoverweight = 1.01 (0.92–1.11), HRobesity = 1.10 (0.94–1.27).
Conclusion
Pre-pregnancy overweight/obesity is associated with an increased risk of ADHD in offspring. The observed association is largely due to unmeasured familial confounding.
Abstract
This paper presents an energy calibration scheme for an upgraded reactor antineutrino detector for the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT). The PROSPECT ...collaboration is preparing an upgraded detector, PROSPECT-II (P-II), to advance capabilities for the investigation of fundamental neutrino physics, fission processes and associated reactor neutrino flux, and nuclear security applications. P-II will expand the statistical power of the original PROSPECT (P-I) dataset by at least an order of magnitude. The new design builds upon
previous P-I design and focuses on improving the detector robustness and long-term stability to enable multi-year operation at one or more sites. The new design optimizes the fiducial volume by elimination of dead space previously occupied by internal calibration channels, which in turn necessitates the external deployment. In this paper, we describe a calibration strategy for P-II. The expected performance of externally deployed calibration sources is evaluated using P-I data and a well-benchmarked simulation package by varying detector segmentation configurations in the analysis. The proposed external calibration scheme delivers a compatible energy scale model and achieves comparable performance with the inclusion of an additional AmBe neutron source, in comparison to the previous internal arrangement. Most importantly, the estimated uncertainty contribution from the external energy scale calibration model meets the precision requirements of the P-II experiment.
Neutral particle detection in high-background environments is greatly aided by the ability to easily load 6Li into liquid scintillators. In this work, we describe a readily available and inexpensive ...liquid scintillation cocktail stably loaded with a Li mass fraction up to 1%. Compositions that give thermodynamically stable microemulsions (reverse-micellar systems) were explored, using a Compton spectrum quenching technique to distinguish these from unstable emulsions. Scintillation light yield and transmittance were characterized. Pulse shape discrimination (PSD) was measured using a 252Cf source, showing that electron-like and proton-like recoil events are well-resolved even for Li loading up to 1%, providing a means of background suppression in neutron/neutrino detectors. While samples in this work were prepared with natLi (7.59% 6Li), the neutron capture peak was clearly visible in the PSD spectrum; this implies that while extremely high capture efficiency could be achieved with 6Li-enriched material, a very inexpensive neutron-sensitive detector can be prepared with natLi.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This Letter reports one of the most precise measurements to date of the antineutrino spectrum from a purely ^{235}U-fueled reactor, made with the final dataset from the PROSPECT-I detector at the ...High Flux Isotope Reactor. By extracting information from previously unused detector segments, this analysis effectively doubles the statistics of the previous PROSPECT measurement. The reconstructed energy spectrum is unfolded into antineutrino energy and compared with both the Huber-Mueller model and a spectrum from a commercial reactor burning multiple fuel isotopes. A local excess over the model is observed in the 5-7 MeV energy region. Comparison of the PROSPECT results with those from commercial reactors provides new constraints on the origin of this excess, disfavoring at 2.0 and 3.7 standard deviations the hypotheses that antineutrinos from ^{235}U are solely responsible and noncontributors to the excess observed at commercial reactors, respectively.
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The Precision Reactor Oscillation and Spectrum (PROSPECT) Experiment is a reactor neutrino experiment designed to search for sterile neutrinos with a mass on the order of 1 eV/c2 and to measure the ...spectrum of electron antineutrinos from a highly-enriched 235U nuclear reactor. The PROSPECT detector consists of an 11 by 14 array of optical segments in 6Li-loaded liquid scintillator at the High Flux Isotope Reactor in Oak Ridge National Laboratory. Antineutrino events are identified via inverse beta decay and read out by photomultiplier tubes located at the ends of each segment. The detector response is characterized using a radioactive source calibration system. This paper describes the design, operation, and performance of the PROSPECT source calibration system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of
...is important when making theoretical predictions. One source of
that is often neglected arises from the irradiation of the nonfuel materials in reactors. The
rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible
sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the
source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel
contributions from HFIR to PROSPECT amount to 1% above the inverse beta decay threshold with a maximum contribution of 9% in the 1.8-2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel
contribution.
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This study identified individuals ever dispensed a selective serotonin reuptake inhibitor (SSRI) aged 15–60 years during 2006–2013, using Swedish national registers. The outcome was violent crime ...conviction. The main statistical analyses assessed risks of violent crime during periods on compared to off SSRI treatment within individuals. Further analyses investigated risk over time in relation to treatment initiation and discontinuation. The study identified 785,337 individuals (64.2% female), experiencing 32,203 violent crimes in 5,707,293 person-years. Between-individual analyses found statistically significantly elevated Hazard Ratios (HRs) overall (HR = 1.10), and in 15–24 and 25–34 year-olds (HR = 1.19 and 1.16), but non-significant HRs in 35–44 and 45–60-year-olds (HR = 1.02 and 1.04). In within-individual analyses, where 2.6% of SSRI users were informative, hazards were elevated overall (HR = 1.26, 95% CI = 1.19, 1.34), and across age groups (HR of 1.35 95% CI = 1.19, 1.54 in 25–34-year-olds to 1.15 95% CI = 0.99, 1.33 in 35–44-year-olds). In the overall cohort, the within-individual HRs were significantly elevated throughout treatment (HRs of 1.24 to 1.35) and for up to 12 weeks post-discontinuation (HRs of 1.37 and 1.20). While questions on causality remain, these results indicate that there may be an increased risk of violent crime during SSRI treatment in a small group of individuals. It may persist throughout medicated periods, across age groups, and after treatment discontinuation. Further confirmation is needed from studies with different designs, and clinical focus should be on high-risk individuals, as a majority of SSRI-users (around 97% in our cohort) will not commit violent crimes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Reactor neutrino experiments have seen major improvements in precision in recent years. With the experimental uncertainties becoming lower than those from theory, carefully considering all sources of ...ν¯e is important when making theoretical predictions. One source of ν¯e that is often neglected arises from the irradiation of the nonfuel materials in reactors. The ν¯e rates and energies from these sources vary widely based on the reactor type, configuration, and sampling stage during the reactor cycle and have to be carefully considered for each experiment independently. In this article, we present a formalism for selecting the possible ν¯e sources arising from the neutron captures on reactor and target materials. We apply this formalism to the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, the ν¯e source for the the Precision Reactor Oscillation and Spectrum Measurement (PROSPECT) experiment. Overall, we observe that the nonfuel ν¯e contributions from HFIR to PROSPECT amount to 1% above the inverse β decay threshold with a maximum contribution of 9% in the 1.8–2.0 MeV range. Nonfuel contributions can be particularly high for research reactors like HFIR because of the choice of structural and reflector material in addition to the intentional irradiation of target material for isotope production. We show that typical commercial pressurized water reactors fueled with low-enriched uranium will have significantly smaller nonfuel ν¯e contribution.
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The PROSPECT and STEREO collaborations present a combined measurement of the pure ^{235}U antineutrino spectrum, without site specific corrections or detector-dependent effects. The spectral ...measurements of the two highest precision experiments at research reactors are found to be compatible with χ^{2}/ndf=24.1/21, allowing a joint unfolding of the prompt energy measurements into antineutrino energy. This νover ¯_{e} energy spectrum is provided to the community, and an excess of events relative to the Huber model is found in the 5-6 MeV region. When a Gaussian bump is fitted to the excess, the data-model χ^{2} value is improved, corresponding to a 2.4σ significance.
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A joint determination of the reactor antineutrino spectra resulting from the fission of ^{235}U and ^{239}Pu has been carried out by the Daya Bay and PROSPECT Collaborations. This Letter reports the ...level of consistency of ^{235}U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant ^{235}U and ^{239}Pu isotopes and improves the uncertainty of the ^{235}U spectral shape to about 3%. The ^{235}U and ^{239}Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the ^{235}U and ^{239}Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.
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