26 research outputs found
Projected sensitivities of the LUX-ZEPLIN experiment to new physics via low-energy electron recoils
LUX-ZEPLIN is a dark matter detector expected to obtain world-leading sensitivity to weakly-interacting massive particles interacting via nuclear recoils with a
∼
7
-tonne xenon target mass. This paper presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment, and 2) an effective neutrino millicharge, both for
p
p
-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axionlike particles forming the Galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6 t 1000 d exposure and low expected rate of electron-recoil backgrounds in the
<
100
 
 
keV
energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout
Germline selection shapes human mitochondrial DNA diversity.
Approximately 2.4% of the human mitochondrial DNA (mtDNA) genome exhibits common homoplasmic genetic variation. We analyzed 12,975 whole-genome sequences to show that 45.1% of individuals from 1526 mother-offspring pairs harbor a mixed population of mtDNA (heteroplasmy), but the propensity for maternal transmission differs across the mitochondrial genome. Over one generation, we observed selection both for and against variants in specific genomic regions; known variants were more likely to be transmitted than previously unknown variants. However, new heteroplasmies were more likely to match the nuclear genetic ancestry as opposed to the ancestry of the mitochondrial genome on which the mutations occurred, validating our findings in 40,325 individuals. Thus, human mtDNA at the population level is shaped by selective forces within the female germ line under nuclear genetic control, which ensures consistency between the two independent genetic lineages.NIHR, Wellcome Trust, MRC, Genomics Englan
Projected sensitivities of the LUX-ZEPLIN (LZ) experiment to new physics via low-energy electron recoils
Projected sensitivity of the LUX-ZEPLIN (LZ) experiment to the two-neutrino and neutrinoless double beta decays of 134Xe
Cosmogenic production of 37Ar in the context of the LUX-ZEPLIN experiment
We estimate the amount of 37Ar produced in natural xenon via cosmic ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth's surface. We then calculate the resulting 37Ar concentration in a 10-tonne payload~(similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea level production rate of 37Ar in natural xenon is estimated to be 0.024~atoms/kg/day. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of 1~tonne/month, the average 37Ar activity after 10~tonnes are purified and transported underground is 0.058--0.090~μBq/kg, depending on the degree of argon removal during above-ground purification. Such cosmogenic 37Ar will appear as a noticeable background in the early science data, while decaying with a 35~day half-life. This newly-noticed production mechanism of 37Ar should be considered when planning for future liquid xenon-based experiments
Proteomic Analysis of the Reproductive Organs of the Hermaphroditic Gastropod Lymnea stagnalis Exposed to Different Endocrine Disrupting Chemicals
Many studies have reported perturbations of mollusc reproduction following exposure to low concentrations (ng/L
range) of endocrine disrupting chemicals (EDCs). However, the mechanisms of action of these molecules on
molluscs are still poorly understood. Investigation of the modifications of protein expression in organisms exposed to
chemicals using proteomic methods can provide a broader and more comprehensive understanding of adverse
impacts of pollution on organisms than conventional biochemical biomarkers (e.g., heat-shock proteins,
metallothioneins, GST, EROD). In this study we have investigated the impacts of four chemicals, which exhibit
different endocrine disrupting properties in vertebrates, on the proteome of the hermaphroditic freshwater pulmonate
gastropod Lymnaea stagnalis after 21 days of exposure. Testosterone, tributyltin, chlordecone and cyproterone
acetate were chosen as tested compounds as they can induce adverse effects on the reproduction of this snail. The
2D-DIGE method was used to identify proteins whose expression was affected by these compounds. In addition to
modifying the expression of proteins involved in the structure and function of the cytoskeleton, chemicals had impacts
on the expression of proteins involved in the reproduction of L. stagnalis. Exposure to 19.2 μg/L of chlordecone
increased the abundance of ovipostatin, a peptide transmitted during mating through seminal fluid, which reduces
oviposition in this species. The expression of yolk ferritin, the vitellogenin equivalent in L. stagnalis, was reduced after
exposure to 94.2 ng Sn/L of tributyltin. The identification of yolk ferritin and the modification of its expression in snails
exposed to chemicals were refined using western blot analysis. Our results showed that the tested compounds
influenced the abundance of yolk ferritin in the reproductive organs. Alteration in proteins involved in reproductive
pathways (e.g., ovipostatin and yolk ferritin) could constitute relevant evidence of interaction of EDCs with
reproductive pathways that are under the control of the endocrine system of L. stagnalis