Crystallization of an exciton superfluid

Indirect excitons -- pairs of electrons and holes spatially separated in semiconductor bilayers or quantum wells -- are known to undergo Bose-Einstein condensation and to form a quantum fluid. Here we show that this superfluid may crystallize upon compression. However, further compression results in quantum melting back to a superfluid. This unusual behavior is explained by the effective interaction potential between indirect excitons which strongly deviates from a dipole potential at small distances due to many-particle and quantum effects. Based on first principle path integral Monte Carlo simulations, we compute the complete phase diagram of this system and predict the relevant parameters necessary to experimentally observe exciton crystallization in semiconductor quantum wells

THE IMPACT OF SELF-HELP GROUP ATTENDANCE ON RELAPSE RATES AFTER ALCOHOL DETOXIFICATION IN A CONTROLLED STUDY

Aims: Self-help groups such as Alcoholics Anonymous (AA) are widely recommended for aftercare of alcohol-dependent persons, even though scientific knowledge of its effectiveness is inconsistent. The aim of the present analysis was to elucidate whether persons attending AA groups regularly after detoxification have lower relapse rates within 1 year, compared to persons without self-help group attendance. Methods: Data for the present analysis were derived from the placebo-group of a multi-centre study in Germany (Wiesbeck et al., 2001). Patients were free to choose either self-help group attendance (N=50) or no support (N=28). Results: After 1-month of follow-up, there was a lower relapse rate in patients attending a self-help group as compared to the control group, a difference, however, that leveled off during the following months. Moreover, relapse rates did not differ significantly at any point of time between both groups. Levels of social functioning improved in both groups over 1 year. Conclusions: The present study was unable to show an advantage of self-help group attendance in reducing relapses compared to the control grou

CONTROLLED STUDY ON THE COMBINED EFFECT OF ALCOHOL AND TOBACCO SMOKING ON TESTOSTERONE IN ALCOHOL-DEPENDENT MEN

Aims: The present study examined the association between pre-treatment drinking and smoking parameters and plasma testosterone levels before and after alcohol withdrawal. Methods: A total of 51 alcohol-dependent men and 43 age-matched healthy men were investigated. In alcoholics, free testosterone in plasma was measured on the day of admission, after detoxification and after 6 weeks of sobriety. Results: While the testosterone level of alcoholic men did not differ from healthy controls at the onset of withdrawal, it was significantly higher for the alcoholics after 6 weeks of sobriety than for the healthy controls. Higher alcohol consumption and higher tobacco use before detoxification led to higher levels of testosterone concentration before and after withdrawal. Conclusions: The effect of alcohol and tobacco is cumulative, with higher levels of alcohol and tobacco consumption being associated with higher levels of testosterone before and after alcohol withdrawa

Transmission Imaging With Axially Overlapping Cone-Beams

We have shown that cone-beam transmission imaging of medium-energy photons that penetrate the parallel-hole collimators can be used to rapidly estimate attenuation maps for use in reconstruction of cardiac SPECT images. Such a transmission imaging geometry offers the advantages of eliminating the need to mechanically move the point-sources during imaging, and minimizes cross-talk between emission and transmission imaging. The axial extent over which artifact-free attenuation maps can be reconstructed is limited by the cone-beam geometry and source collimation. We investigated irradiation of a single head by multiple point-sources such that their asymmetric cone-beam fields overlap in the axial direction as a method of extending the axial coverage of the patient. This study reports on testing of a penalized-likelihood algorithm for transmission reconstruction of overlapping cone-beams. This algorithm was evaluated through MCAT simulations and applied to transmission measurements of an anthropomorphic phantom. The experimental work consisted of performing a series of flood and transmission measurements on the anthropomorphic phantom with shifted axial locations of point-sources. We summed the projection data from individual measurements to simulate the projection data for a multiple point-source system. With the proposed penalized-Iikelihood algorithm, the full axial extent (20.5 cm) of the anthropomorphic phantom was reconstructed for the overlapping cone-beam geometry with 2 point-sources per camera head.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85904/1/Fessler202.pd

Total and Methyl Mercury Contents and Distribution Characteristics in Cicada, Cryptotympana atrata (Fabricius)

Total and methyl mercury concentrations of cicada bodies, wings, and exuviae were investigated to study the mercury distribution characteristics. Results indicated that total and methyl mercury concentrations of cicada bodies were 2.64 mg/kg and 123.93 ng/g on average, respectively. In cicada tissues, total mercury concentrations were found to increase in the order of exuviae (0.50 mg/kg on average) < wings (0.98 mg/kg on average) < cicada bodies (2.64 mg/kg on average) and methyl mercury concentrations of cicada bodies were 123.93 ng/g on average and were the highest. Methyl mercury concentrations accounted for about 4.69% of total mercury in cicada bodies and most mercury was in inorganic forms in cicada. Sex differences of total mercury concentrations were significantly great (F = 8.433, p < 0.01) and total mercury concentrations of the males, which were 3.38 mg/kg on average, were much higher. Correlation analysis showed that neither total nor methyl mercury concentrations of cicada bodies was significantly related to the corresponding contents of soil (r = 0.0598, p > 0.05)

Ocean mass, sterodynamic effects, and vertical land motion largely explain US coast relative sea level rise

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Harvey, T., Hamlington, B. D., Frederikse, T., Nerem, R. S., Piecuch, C. G., Hammond, W. C., Blewitt, G., Thompson, P. R., Bekaert, D. P. S., Landerer, F. W., Reager, J. T., Kopp, R. E., Chandanpurkar, H., Fenty, I., Trossman, D. S., Walker, J. S., & Boening, C. W. Ocean mass, sterodynamic effects, and vertical land motion largely explain US coast relative sea level rise. Communications Earth & Environment, 2(1), (2021): 233, https://doi.org/10.1038/s43247-021-00300-w.Regional sea-level changes are caused by several physical processes that vary both in space and time. As a result of these processes, large regional departures from the long-term rate of global mean sea-level rise can occur. Identifying and understanding these processes at particular locations is the first step toward generating reliable projections and assisting in improved decision making. Here we quantify to what degree contemporary ocean mass change, sterodynamic effects, and vertical land motion influence sea-level rise observed by tide-gauge locations around the contiguous U.S. from 1993 to 2018. We are able to explain tide gauge-observed relative sea-level trends at 47 of 55 sampled locations. Locations where we cannot explain observed trends are potentially indicative of shortcomings in our coastal sea-level observational network or estimates of uncertainty.The research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. C.G.P. was supported by NASA grant 80NSSC20K1241. B.D.H., T.C.H., and T.F. were supported by NASA JPL Task 105393.281945.02.25.04.59. R.E.K. and J.S.W. were supported by U.S. National Aeronautics and Space Administration (grants 80NSSC17K0698, 80NSSC20K1724 and JPL task 105393.509496.02.08.13.31) and U.S. National Science Foundation (grant ICER-1663807). P.R.T. acknowledges financial support from the NOAA Global Ocean Monitoring and Observing program in support of the University of Hawaii Sea Level Center (NA11NMF4320128). The ECCO project is funded by the NASA Physical Oceanography; Modeling, Analysis, and Prediction; and Cryosphere Programs

Mercury Bioaccumulation and Prediction in Terrestrial Insects from Soil in Huludao City, Northeast China

Mercury accumulation was investigated by constructing and testing empirical equations based on mercury in soil (Cs) and in 10 terrestrial insects (Ci). Cs ranged from 0.13 to 41.01 mg/kg. Ci differed with species and the highest was found in dragonfly. Cs and Ci showed a good linear fit, and a simple equation was used in predicting Ci when insects were classified into one Insecta group (r = 0.3399, p = 0.0037). The taxonomy can affect validities of empirical equations, which fit field data well when insects were grouped by feeding habits, and when grouped by species, empirical equations were suitable only for certain insects

A practical indicator for surface ocean heat and freshwater buoyancy fluxes and its application to the NCEP reanalysis data

The buoyancy flux at the air/sea interface plays a key role in water mass transformation and mixing as it modifies surface water density and in turn drives overturning and enhances stratification. It is the interplay of these two independent heat and freshwater buoyancy flux components that is of central importance when analysing mechanisms of the ocean/atmosphere interaction. Here, a diagnostic quantity (ΘB) is presented that allows to capture the relative contribution of both components on the buoyancy flux in one single quantity. Using NCEP reanalysis of heat and freshwater fluxes (1948–2009) demonstrates that ΘB is a convenient tool to analyse both the temporal and spatial variability of their corresponding buoyancy fluxes. For the global ocean the areal extent of buoyancy gain and loss regions changed by 10%, with the largest extent of buoyancy gain during the 1970–1990 period. In the subpolar North Atlantic, and likewise in the South Pacific, decadal variability in freshwater flux is pronounced and, for the latter region, takes control over the total buoyancy flux since the 1980s. Some of the areal extent time series show a significant correlation with large-scale climate indices