Many extensions of the standard model of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult ...to confirm. Observation of neutrinoless double-β decay (0νββ), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with (76)Ge (the GERDA experiment) and (136)Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 10(25) years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Here we report new results from EXO-200 based on a large (136)Xe exposure that represents an almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9 × 10(25) years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0νββ decay and set a half-life limit of 1.1 × 10(25) years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0νββ decay searches with an improved Xe-based experiment, nEXO.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The timing of annual life‐history events affects survival and reproduction of all organisms. A changing environment can perturb phenological adaptations and an important question is if populations ...can evolve fast enough to track the environmental changes. Yet, little is known about selection and evolutionary potential of traits determining the timing of crucial annual events. Migratory species, which travel between different climatic regions, are particularly affected by global environmental changes. To increase our understanding of evolutionary potential and selection of timing traits, we investigated the quantitative genetics of arrival date at the breeding ground using a multigenerational pedigree of a natural great reed warbler (Acrocephalus arundinaceus) population. We found significant heritability of 16.4% for arrival date and directional selection for earlier arrival in both sexes acting through reproductive success, but not through lifespan. Mean arrival date advanced with 6 days over 20 years, which is in exact accordance with our predicted evolutionary response based on the breeder's equation. However, this phenotypic change is unlikely to be caused by microevolution, because selection seems mainly to act on the nongenetic component of the trait. Furthermore, demographical changes could also not account for the advancing arrival date. Instead, a strong correlation between spring temperatures and population mean arrival date suggests that phenotypic plasticity best explains the advancement of arrival date in our study population. Our study dissects the evolutionary and environmental forces that shape timing traits and thereby increases knowledge of how populations cope with rapidly changing environments.
Astrophysical observations indicate that dark matter constitutes most of the mass in our universe, but its nature remains unknown. Over the past decade, the Cryogenic Dark Matter Search (CDMS II) ...experiment has provided world-leading sensitivity for the direct detection of weakly interacting massive particle (WIMP) dark matter. The final exposure of our low-temperature germanium particle detectors at the Soudan Underground Laboratory yielded two candidate events, with an expected background of 0.9 ± 0.2 events. This is not statistically significant evidence for a WIMP signal. The combined CDMS II data place the strongest constraints on the WIMP-nucleon spin-independent scattering cross section for a wide range of WIMP masses and exclude new parameter space in inelastic dark matter models.
Mogrosides are the primary components responsible for the sweet taste of Monk fruit which is derived from Siraitia grosvenorii (Swingle), a herbaceous plant native to southern China. Many mogrosides ...have been identified from Monk fruit extract, but the major sweetness component of Monk fruit by mass is mogroside V, comprising up to 0.5% of the dried fruit weight. Recent pharmacokinetic studies indicate that the parent mogrosides undergo minimal systemic absorption following ingestion and hydrolysis by digestive enzymes and/or intestinal flora and are excreted as mogrol (i.e., the aglycone) and its mono- and diglucosides. The objective of this study was to demonstrate whether individual mogrosides, are metabolized to a common and terminal deglycosylated metabolite, mogrol. An in vitro assay was conducted with pooled human male and female intestinal fecal homogenates (HFH) using mogrosides IIIe, mogroside V, siamenoside I, and isomogroside V at two concentrations over a 48 h period. The results show that various mogrosides that differ in the linkages and number of glucose units attached to a common cucurbitane backbone, share a common metabolic fate, and are metabolized within 24 h to mogrol. Aside from an apparent difference in the initial rate of deglycosylation between mogrosides at higher concentrations, no apparent difference in the rate of deglycosylation was observed between the male and female HFH. Given the similar structures of these mogrosides and a shared metabolic fate to mogrol, the study provides support for a reasonably conservative approach to assess safety based on bridging safety data from an individual mogroside (i.e., Mogroside V) to other mogrosides, and the establishment of a group Acceptable Daily Intake (ADI), rather than individual ADI's for mogrosides.
•Metabolism of mogrosides was evaluated using an in vitro human fecal homogenate assay.•Results demonstrate mogrosides share a common metabolic pathway to mogrol.•Study provides support for bridging safety data from an individual mogroside to other mogrosides.•In vivo safety data and metabolism could support a group ADI for mogrosides.
We report results from the Cryogenic Dark Matter Search at the Soudan Underground Laboratory (CDMS II) featuring the full complement of 30 detectors. A blind analysis of data taken between October ...2006 and July 2007 sets an upper limit on the weakly interacting massive particle (WIMP) nucleon spin-independent cross section of 6.6x10;{-44} cm;{2} (4.6x10;{-44} cm;{2} when combined with previous CDMS II data) at the 90% confidence level for a WIMP mass of 60 GeV/c;{2}. This achieves the best sensitivity for dark matter WIMPs with masses above 44 GeV/c;{2}, and significantly restricts the parameter space for some favored supersymmetric models.
X‐ray free‐electron lasers (XFELs) deliver pulses of coherent X‐rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the ...intensity and the centroid of the beam fluctuate strongly on a pulse‐to‐pulse basis, motivating high‐rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X‐ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi‐GHz) pass‐through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron–hole plasma density.
Two approaches to the design of a diamond sensor signal path were explored using high‐intensity X‐ray pulses from the LINAC Coherent Light Source at SLAC. Results on the charge‐collection efficiency and signal collection time are presented over a range of approximately four orders of magnitude in the generated electron–hole plasma density.
•Anaerobic metabolism of rebaudiosides A, B, D, and M was evaluated.•Pooled human fecal homogenates from males and females used as source of metabolism.•Metabolism to steviol of all rebaudiosides was ...complete after 24h incubation.•Safety data on other steviol glycosides are relevant to rebaudiosides B, D, and M.
The hydrolysis of the steviol glycosides rebaudioside A, B, D, and M, as well as of steviolbioside (a metabolic intermediate) to steviol was evaluated in vitro using human fecal homogenates from healthy donors under anaerobic conditions. Incubation of each of the rebaudiosides resulted in rapid hydrolysis to steviol. Metabolism was complete within 24h, with the majority occurring within the first 8h. There were no clear differences in the rate or extent of metabolism of rebaudioside B, D, or M, relative to the comparative control rebaudioside A. The hydrolysis of samples containing 2.0mg/mL of each rebaudioside tended to take slightly longer than solutions containing 0.2mg/mL. There was no apparent gender differences in the amount of metabolism of any of the rebaudiosides, regardless of the concentrations tested. An intermediate in the hydrolysis of rebaudioside M to steviol, steviolbioside, was also found to be rapidly degraded to steviol. The results demonstrate that rebaudiosides B, D, and M are metabolized to steviol in the same manner as rebaudioside A. These data support the use of toxicology data available on steviol, and on steviol glycosides metabolized to steviol (i.e., rebaudioside A) to substantiate the safety of rebaudiosides B, D, and M.
Abstract
We present the first results from the HPSoC ASIC designed for readout of Ultra-fast Silicon Detectors. The 4-channel ASIC manufactured in 65 nm CMOS by TSMC has been optimized for 50 μm ...thick AC-LGAD. The evaluation of the analog front end with β-particles impinging on 3 × 3 AC-LGAD arrays (500 μm pitch, 200 × 200 μm
2
metal) confirms a fast output rise time of 600 ps and good timing performance with a jitter of 45 ps. Further calibration experiments and TCT laser studies indicate some gain limitations that are being investigated and are driving the design of the second-generation pre-amplification stages to reach a jitter of 15 ps.
The GERmanium Detector Array, Gerda, searches for neutrinoless double β decay in 76Ge using bare high-purity germanium detectors submerged in liquid argon. For the calibration of these detectors γ ...emitting sources have to be lowered from their parking position on the top of the cryostat over more than 5m down to the germanium crystals. With the help of Monte Carlo simulations, the relevant parameters of the calibration system were determined. It was found that three 228Th sources with an activity of 20kBq each at two different vertical positions will be necessary to reach sufficient statistics in all detectors in less than 4h of calibration time. These sources will contribute to the background of the experiment with a total of (1.07±0.04(stat)−0.19+0.13(sys))×10−4cts/(keVkgyr)) when shielded from below with 6cm of tantalum in the parking position.
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