The PROSPECT reactor antineutrino experiment Ashenfelter, J.; Balantekin, A.B.; Baldenegro, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
922
Journal Article
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The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, is designed to make both a precise measurement of the antineutrino spectrum from a highly-enriched uranium reactor and to probe ...eV-scale sterile neutrinos by searching for neutrino oscillations over meter-long baselines. PROSPECT utilizes a segmented6Li-doped liquid scintillator detector for both efficient detection of reactor antineutrinos through the inverse beta decay reaction and excellent background discrimination. PROSPECT is a movable 4-ton antineutrino detector covering distances of 7m to 13m from the High Flux Isotope Reactor core. It will probe the best-fit point of the ν̄e disappearance experiments at 4σ in 1 year and the favored regions of the sterile neutrino parameter space at more than 3σ in 3 years. PROSPECT will test the origin of spectral deviations observed in recent θ13 experiments, search for sterile neutrinos, and address the hypothesis of sterile neutrinos as an explanation of the reactor anomaly. This paper describes the design, construction, and commissioning of PROSPECT and reports first data characterizing the performance of the PROSPECT antineutrino detector.
Early and late extremes in the timing of snowmelt have recently been observed in the Pacific Arctic. Subseasonal‐to‐seasonal forecasts of this timing are important for industry, environmental ...management, and Arctic communities. In northern Alaska, the timing is influenced by the advection of marine air from the north Pacific by the Aleutian Low, modulated by high pressure centered in the Beaufort Sea. A new climate index that integrates their interaction could advance melt predictions. We define this index based on 850‐hPa geopotential height at four fixed locations and refer to it as the Aleutian Low‐Beaufort Sea Anticyclone (ALBSA). During positive ALBSA in May, advection of +0.5‐1.5 K/day is observed through the Bering Strait. ALBSA is correlated with both snowmelt in northern Alaska and the onset of sea ice melt over the adjacent seas. ALBSA therefore may be suitable for monitoring the relevant circulation patterns and for developing predictive tools.
Plain Language Summary
Early and late extremes in the timing of snowmelt have recently been observed in northern Alaska. Forecasts of this timing with lead times of weeks to months are important for area stakeholders including industry, environmental managers, and Arctic communities. We find that transport of air masses from the north Pacific influences the timing of melt in the region. We introduce a new index called the Aleutian Low‐Beaufort Sea Anticyclone (ALBSA). When ALBSA is positive, warm Pacific air is observed over the Bering Strait and in the far western Arctic seas. ALBSA is correlated with the timing of spring melt and therefore may be suitable for both monitoring and prediction.
Key Points
Record early and late anomalies in the timing of snowmelt in northern Alaska have been observed from 2015‐2018
Timing of snowmelt is linked to atmospheric transport of air masses from the north Pacific
A climate index is introduced that is sensitive to the implicated advection and may be useful as a monitoring or prediction tool
Piezo channels are a ubiquitously expressed, principal type of molecular force sensor in eukaryotes. They enable cells to decode a myriad of physical stimuli and are essential components of numerous ...mechanosensory processes. Central to their physiological role is the ability to change conformation in response to mechanical force. Here we discuss the evolutionary origin of Piezo in relation to other MS channels in addition to the force that gates Piezo channels. In particular, we discuss whether Piezo channels are inherently mechanosensitive in accordance with the force-from-lipid paradigm which has been firmly established for bacterial MS channels and two-pore domain K
(K
) channels. We also discuss the evidence supporting a reliance on or direct interaction with structural scaffold proteins of the cytoskeleton and extracellular matrix according to the force-from-filament principle. In doing so, we explain the false dichotomy that these distinctions represent. We also discuss the possible unifying models that shed light on channel mechanosensitivity at the molecular level.
Microstructural degradation in the CMSX-4 single crystal superalloy during creep deformation at 1150
°C and 100
MPa is studied. Tensile deformation in the 〈0
0
1〉 direction is considered due to its ...technological importance. Under these conditions, rafting of the γ′ structure is completed quickly and within the first 10
h. It is demonstrated that the creep rupture event is highly localised, the instability being associated with a critical and well-defined strain being reached with failure occurring within a further few tens of hours. It is shown that the high strain rates and shear stresses associated with the rupture process are sufficient to cause realignment of the rafted γ′ structure with respect to the γ matrix. Creep cavitation damage near to the rupture surface is prevalent, at microporosity inherited from the casting process but more significantly, at topologically close-packed (TCP) phases and associated pores and voids formed in their vicinity which have formed
via vacancy condensation. Hot isostatic pressing (HIPing) prior to creep testing reduces the incidence of casting microporosity, but the creep rupture life is not improved significantly. It is suggested that it is the formation of TCP phases which limits creep rupture life.
The selective pressures exerted by predation can have considerable influence on the behavior of prey species across a wide range of taxa. Within a species, this force may differ between the sexes, ...leading to sex‐specific behavioral responses to predators. We tested whether the black spiny‐tailed iguana Ctenosaura similis is able to use auditory cues to detect an avian predator and whether antipredator responses differ in a sex‐dependent fashion. We conducted behavioral assays in which a food item was used as bait while iguanas were subjected to a recording of a Harris's hawk or white noise as a control. We found that a significantly greater percentage of individuals of either sex responded to the hawk call than to the white noise. We also found that a significantly greater percentage of females than males responded to either sound. These results suggest that not only do black spiny‐tailed iguanas incorporate auditory cues into predator detection, but that antipredator behavioral responses differ between the sexes as well. Such sex‐specific behaviors can be attributed to morphological and endocrine differences between male and female iguanas. These findings may also lend insight into how behavior can influence the evolution of sexual dimorphism within a species.
Predation pressure can have considerable influence on the behavior of prey species and may differ between the sexes, which can lead to sex‐specific evolution of behavioral responses to different sensory cues. For black spiny‐tailed iguanas Ctenosaura similis, we found that more individuals of either sex responded to a predatory hawk call than to white noise, and that more females than males responded to either sound. Our findings suggest that not only do black spiny‐tailed iguanas incorporate auditory cues into predator detection, but that antipredator behavioral responses differ between the sexes as well, lending insight into how behavior can influence the evolution of sexual dimorphism within a species.
The creep performance of 〈001〉-orientated CMSX-4 superalloy single crystals at temperatures beyond 1000°C is analysed. Rafting of the
γ′ structure occurs rapidly, e.g. for the 1150°C/100
MPa tests ...rafting is completed within the first 10
h. At this stage and for a considerable time thereafter the creep strain rate decreases with increasing strain, implying a creep hardening effect which is absent at lower temperatures when the kinetics of rafting is less rapid. Once a critical strain
ε* of (0.7±0.3)% is reached, the creep strain increases dramatically and failure occurs within a few tens of hours. It is demonstrated that methods of interpretation which, assume a proportionality between the creep strain rate and creep strain, are unable to account for creep hardening which occurs as a consequence of rafting. A modification is proposed which accounts for the blocking of the glide/climb of
{111}〈1
1
̄
0〉
creep dislocations which occurs as the number of vertical
γ channels is reduced and cellular dislocation networks become stabilized. Consequently, failure must be taken to be associated with creep cavitation, which occurs predominantly around casting porosity. It is emphasized that more work is required to quantify the interaction between the various creep damage mechanisms.
Memory is strongly influenced by stress but underlying mechanisms are unknown. Here, we used electrophysiology, neuroanatomy, and network simulations to probe the role of the endogenous, ...stress-related neuropeptide corticotropin-releasing hormone (CRH) in modulating hippocampal function. We focused on neuronal excitability and the incidence of sharp waves (SPWs), a form of intrinsic network activity associated with memory consolidation. Specifically, we blocked endogenous CRH using 2 chemically distinct antagonists of the principal hippocampal CRH receptor, CRHR1. The antagonists caused a modest reduction of spontaneous excitatory transmission onto CA3 pyramidal cells, mediated, in part by effects on IAHP. This was accompanied by a decrease in the incidence but not amplitude of SPWs, indicating that the synaptic actions of CRH are sufficient to alter the output of a complex hippocampal network. A biophysical model of CA3 described how local actions of CRH produce macroscopic consequences including the observed changes in SPWs. Collectively, the results provide a first demonstration of the manner in which subtle synaptic effects of an endogenously released neuropeptide influence hippocampal network level operations and, in the case of CRH, may contribute to the effects of acute stress on memory.
The origin and possible universality of the stellar initial mass function (IMF) is a major issue in astrophysics. One of the main objectives of the Herschel Gould Belt Survey is to clarify the link ...between the prestellar core mass function (CMF) and the IMF. We present and discuss the core mass function derived from Herschel data for the large population of prestellar cores discovered with SPIRE and PACS in the Aquila rift cloud complex at d ~ 260 pc. We detect a total of 541 starless cores in the entire ~11 deg2 area of the field imaged at 70–500 μm with SPIRE/PACS. Most of these cores appear to be gravitationally bound, and thus prestellar in nature. Our Herschel results confirm that the shape of the prestellar CMF resembles the stellar IMF, with much higher quality statistics than earlier submillimeter continuum ground-based surveys.
The sidereal time dependence of MiniBooNE νe and ν¯e appearance data is analyzed to search for evidence of Lorentz and CPT violation. An unbinned Kolmogorov–Smirnov (K–S) test shows both the νe and ...ν¯e appearance data are compatible with the null sidereal variation hypothesis to more than 5%. Using an unbinned likelihood fit with a Lorentz-violating oscillation model derived from the Standard Model Extension (SME) to describe any excess events over background, we find that the νe appearance data prefer a sidereal time-independent solution, and the ν¯e appearance data slightly prefer a sidereal time-dependent solution. Limits of order 10−20 GeV are placed on combinations of SME coefficients. These limits give the best limits on certain SME coefficients for νμ→νe and ν¯μ→ν¯e oscillations. The fit values and limits of combinations of SME coefficients are provided.
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