This Letter reports the first measurement of the 235U $\bar{ν}$e energy spectrum by PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, operating 7.9 m from the 85 MWth highly ...enriched uranium (HEU) High Flux Isotope Reactor. With a surface-based, segmented detector, PROSPECT has observed 31678±304(stat) $\bar{ν}$e-induced inverse beta decays, the largest sample from HEU fission to date, 99% of which are attributed to 235U. Despite broad agreement, comparison of the Huber 235U model to the measured spectrum produces a χ2/ndf=51.4/31, driven primarily by deviations in two localized energy regions. The measured 235U spectrum shape is consistent with a deviation relative to prediction equal in size to that observed at low-enriched uranium power reactors in the $\bar{ν}$e energy region of 5–7 MeV.
The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spin-independent cross-section down to (1--2)\(\times10^{-12}\)\,pb at a WIMP mass of 40 GeV/\(c^2\). This paper ...describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data.
The purpose of these studies was to evaluate the effects of chronic caffeine ingestion on the myocardium during fetal and neonatal growth and development. The isolated perfused working heart ...preparation was used to evaluate cardiac function. During gestation and lactation, one group of dams consumed a caffeine supplemented diet (10 mg/kg/day). Their offspring were sacrificed and the hearts analyzed 50 days after birth. We found that the intake of caffeine by the dams resulted in significant increases in the offspring's coronary flow, peak systolic pressure, and myocardial work. A second group of dams ingested a diet containing caffeine (10 mg/kg/day) during lactation only. Their pups continued to consume the caffeine diet until 50 days. Pup hearts exhibited significant reductions in cardiac output, stroke volume, pressure development, myocardial work, and external efficiency when compared to controls. Caffeine did not affect body or heart weight or adipose size or number in these experiments. Thus, continued caffeine consumption following birth may alter cardiac performance of the offspring.
Phys. Rev. C 102, 014602 (2020) The LUX-ZEPLIN (LZ) experiment will enable a neutrinoless double beta decay
search in parallel to the main science goal of discovering dark matter particle
...interactions. We report the expected LZ sensitivity to $^{136}$Xe neutrinoless
double beta decay, taking advantage of the significant ($>$600 kg) $^{136}$Xe
mass contained within the active volume of LZ without isotopic enrichment.
After 1000 live-days, the median exclusion sensitivity to the half-life of
$^{136}$Xe is projected to be 1.06$\times$10$^{26}$ years (90% confidence
level), similar to existing constraints. We also report the expected
sensitivity of a possible subsequent dedicated exposure using 90% enrichment
with $^{136}$Xe at 1.06$\times$10$^{27}$ years.
A 30-g xenon bubble chamber, operated at Northwestern University in June and November 2016, has for the first time observed simultaneous bubble nucleation and scintillation by nuclear recoils in a ...superheated liquid. This chamber is instrumented with a CCD camera for near-IR bubble imaging, a solar-blind photomultiplier tube to detect 175-nm xenon scintillation light, and a piezoelectric acoustic transducer to detect the ultrasonic emission from a growing bubble. The time of nucleation determined from the acoustic signal is used to correlate specific scintillation pulses with bubble-nucleating events. We report on data from this chamber for thermodynamic "Seitz" thresholds from 4.2 to 15.0 keV. The observed single- and multiple-bubble rates when exposed to a ^{252}Cf neutron source indicate that, for an 8.3-keV thermodynamic threshold, the minimum nuclear recoil energy required to nucleate a bubble is 19±6 keV (1σ uncertainty). This is consistent with the observed scintillation spectrum for bubble-nucleating events. We see no evidence for bubble nucleation by gamma rays at any of the thresholds studied, setting a 90% C.L. upper limit of 6.3×10^{-7} bubbles per gamma interaction at a 4.2-keV thermodynamic threshold. This indicates stronger gamma discrimination than in CF_{3}I bubble chambers, supporting the hypothesis that scintillation production suppresses bubble nucleation by electron recoils, while nuclear recoils nucleate bubbles as usual. These measurements establish the noble-liquid bubble chamber as a promising new technology for the detection of weakly interacting massive particle dark matter and coherent elastic neutrino-nucleus scattering.
Experiments were conducted to determine whether chronic caffeine consumption during early growth and development affected cardiac performance and development of adipose tissue. Dams were fed a ...nutritionally complete diet with or without the addition of 10 mg/kg caffeine during lactation. After weaning, the pups were maintained on this diet until they were sacrificed at 88 days of age. Body weight at the time of sacrifice was comparable for both groups. The hearts from caffeine-fed animals were significantly (P less than 0.05) larger based on both dry and wet weights although the dry weight/wet weight ratios were similar. Ventricular function curves were generated on each heart using an isolated working heart preparation. The isolated hearts of caffeine-fed rats exhibited a significant reduction in cardiac output, stroke volume, mean aortic pressure, and estimated myocardial work when compared to controls. The rats fed caffeine had greater plasma triglyceride levels with no significant differences in adipocyte size or number in the epididymal and perirenal depots. It is concluded that chronic caffeine intake from birth may alter cardiac function of the offspring.
COVID‐19 in lung transplant recipients Myers, Catherine N.; Scott, John Harwood; Criner, Gerard J. ...
Transplant infectious disease,
December 2020, Letnik:
22, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Solid organ transplant recipients are considered at high risk for COVID‐19 infection due to chronic immune suppression; little data currently exists on the manifestations and outcomes of COVID‐19 ...infection in lung transplant recipients. Here we report 8 cases of COVID‐19 identified in patients with a history of lung transplant. We describe the clinical course of disease as well as preexisting characteristics of these patients.
Cryogenic calorimetric experiments to search for neutrinoless double-beta decay (\(0\nu\beta\beta\)) are highly competitive, scalable and versatile in isotope. The largest planned detector array, ...CUPID, is comprised of about 1500 individual Li\(_2^{100}\)MoO\(_{4}\) detector modules with a further scale up envisioned for a follow up experiment (CUPID-1T). In this article, we present a novel detector concept targeting this second stage with a low impedance TES based readout for the Li\(_2\)MoO\(_{4}\) absorber that is easily mass-produced and lends itself to a multiplexed readout. We present the detector design and results from a first prototype detector operated at the NEXUS shallow underground facility at Fermilab. The detector is a 2-cm-side cube with 21\(\,\)g mass that is strongly thermally coupled to its readout chip to allow rise-times of \(\sim\)0.5\(\,\)ms. This design is more than one order of magnitude faster than present NTD based detectors and is hence expected to effectively mitigate backgrounds generated through the pile-up of two independent two neutrino decay events coinciding close in time. Together with a baseline resolution of 1.95\(\,\)keV (FWHM) these performance parameters extrapolate to a background index from pile-up as low as \(5\cdot 10^{-6}\,\)counts/keV/kg/yr in CUPID size crystals. The detector was calibrated up to the MeV region showing sufficient dynamic range for \(0\nu\beta\beta\) searches. In combination with a SuperCDMS HVeV detector this setup also allowed us to perform a precision measurement of the scintillation time constants of Li\(_2\)MoO\(_{4}\). The crystal showed a significant fast scintillation emission with O(10\(\,\mu\)s) time-scale, more than an order below the detector response of presently considered light detectors suggesting the possibility of further progress in pile-up rejection through better light detectors in the future.
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a ...finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature T(cdw). Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at T(cdw) marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in 'pseudogap' states.
Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted ...by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0–3300 keV) varied from 596 Hz to 1355 Hz for unshielded measurements, corresponding to a total flux from the cavern walls of 1.9 ± 0.4 γ cm−2s−1. The resulting activity in the walls of the cavern can be characterised as 220 ± 60 Bq/kg of 40K, 29 ± 15 Bq/kg of 238U, and 13 ± 3 Bq/kg of 232Th.
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