318 research outputs found
Thermodynamic properties and structural stability of thorium dioxide
Using density functional theory (DFT) calculations, we have systematically
investigated the thermodynamic properties and structural stabilities of thorium
dioxide (ThO). Based on the calculated phonon dispersion curves, we
calculate the thermal expansion coefficient, bulk modulus, and heat capacities
at different temperatures for ThO under the quasi-harmonic approximation.
All the results are in good agreement with corresponding experiments proving
the validity of our methods. Our theoretical studies can help people more
clearly understand the thermodynamic behaviors of ThO at different
temperatures. In addition, we have also studied possible defect formations and
diffusion behaviors of helium in ThO, to discuss its structural stability.
It is found that in intrinsic ThO without any Fermi energy shifts, the
interstitial Th defect other than oxygen or thorium vacancies,
interstitial oxygen, and any kinds of Frenkel pairs, is most probable to form
with an energy release of 1.74 eV. However, after upshifting the Fermi energy,
the formation of the other defects also becomes possible. For helium diffusion,
we find that only through the thorium vacancy can it happen with the small
energy barrier of 0.52 eV. Otherwise, helium atoms can hardly incorporate or
diffuse in ThO. Our results indicate that people should prevent upshifts of
the Fermi energy of ThO to avoid the formation of thorium vacancies and so
as to prevent helium caused damages.Comment: 11 pages, 11 figure
Gender and sexual orientation differences in cognition across adulthood : age is kinder to women than to men regardless of sexual orientation
Despite some evidence of greater age-related deterioration of the brain in males than in females, gender differences in rates of cognitive aging have proved inconsistent. The present study employed web-based methodology to collect data from people aged 20-65 years (109,612 men; 88,509 women). As expected, men outperformed women on tests of mental rotation and line angle judgment, whereas women outperformed men on tests of category fluency and object location memory. Performance on all tests declined with age but significantly more so for men than for women. Heterosexuals of each gender generally outperformed bisexuals and homosexuals on tests where that gender was superior; however, there were no clear interactions between age and sexual orientation for either gender. At least for these particular tests from young adulthood to retirement, age is kinder to women than to men, but treats heterosexuals, bisexuals, and homosexuals just the same
An upper limit on the electron-neutrino flux from the HiRes detector
Air-fluorescence detectors such as the High Resolution Fly's Eye (HiRes)
detector are very sensitive to upward-going, Earth-skimming ultrahigh energy
electron-neutrino-induced showers. This is due to the relatively large
interaction cross sections of these high-energy neutrinos and to the
Landau-Pomeranchuk-Migdal (LPM) effect. The LPM effect causes a significant
decrease in the cross sections for bremsstrahlung and pair production, allowing
charged-current electron-neutrino-induced showers occurring deep in the Earth's
crust to be detectable as they exit the Earth into the atmosphere. A search for
upward-going neutrino-induced showers in the HiRes-II monocular dataset has
yielded a null result. From an LPM calculation of the energy spectrum of
charged particles as a function of primary energy and depth for
electron-induced showers in rock, we calculate the shape of the resulting
profile of these showers in air. We describe a full detector Monte Carlo
simulation to determine the detector response to upward-going
electron-neutrino-induced cascades and present an upper limit on the flux of
electron-neutrinos.Comment: 13 pages, 3 figures. submitted to Astrophysical Journa
Search for Correlations between HiRes Stereo Events and Active Galactic Nuclei
We have searched for correlations between the pointing directions of
ultrahigh energy cosmic rays observed by the High Resolution Fly's Eye
experiment and Active Galactic Nuclei (AGN) visible from its northern
hemisphere location. No correlations, other than random correlations, have been
found. We report our results using search parameters prescribed by the Pierre
Auger collaboration. Using these parameters, the Auger collaboration concludes
that a positive correlation exists for sources visible to their southern
hemisphere location. We also describe results using two methods for determining
the chance probability of correlations: one in which a hypothesis is formed
from scanning one half of the data and tested on the second half, and another
which involves a scan over the entire data set. The most significant
correlation found occurred with a chance probability of 24%.Comment: 13 pages, 1 table, 5 figure
Building the New Europe: Western and Eastern Roads to Social Partnership
[Excerpt] While the ways in which neoliberalism and economic integration undermine social partnership and the welfare state have been extensively studied, less attention has been given to the ways in which such economic forces may push actors together, in reinvigorated bargaining relationships, to find workable solutions to difficult problems. In his article, we examine the contemporary status of social partnership in four case study countries—Germany, the United Kingdom, Bulgaria and Poland—as well as for Europe as a whole. In the west, while Germany presents a case of established social partnership under pressure, the United Kingdom has stood over the past two decades on the opposite neoliberal side. In the east, Bulgaria is one of the more developed cases of post-communist tripartism, while Poland exemplifies a weaker tripartism that emerged at a later stage of the transformation process. In selecting more and less developed social partnership cases in both west and east, we test the argument that the rise of Thatcher/Reagan/ Friedman ‘free market economics’ is paradoxically driving a resurgence and consolidation of social partnership relations across the new (both western and eastern) Europe
Search for Anisotropy of Ultra-High Energy Cosmic Rays with the Telescope Array Experiment
We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events
collected by the Telescope Array (TA) detector in the first 40 months of
operation. Following earlier studies, we examine event sets with energy
thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the
events in right ascension and declination are compatible with an isotropic
distribution in all three sets. We then compare with previously reported
clustering of the UHECR events at small angular scales. No significant
clustering is found in the TA data. We then check the events with E>57 EeV for
correlations with nearby active galactic nuclei. No significant correlation is
found. Finally, we examine all three sets for correlations with the large-scale
structure of the Universe. We find that the two higher-energy sets are
compatible with both an isotropic distribution and the hypothesis that UHECR
sources follow the matter distribution of the Universe (the LSS hypothesis),
while the event set with E>10 EeV is compatible with isotropy and is not
compatible with the LSS hypothesis at 95% CL unless large deflection angles are
also assumed. We show that accounting for UHECR deflections in a realistic
model of the Galactic magnetic field can make this set compatible with the LSS
hypothesis.Comment: 10 pages, 9 figure
LRRTM3 Interacts with APP and BACE1 and Has Variants Associating with Late-Onset Alzheimer's Disease (LOAD)
Leucine rich repeat transmembrane protein 3 (LRRTM3) is member of a synaptic protein family. LRRTM3 is a nested gene within α-T catenin (CTNNA3) and resides at the linkage peak for late-onset Alzheimer’s disease (LOAD) risk and plasma amyloid β (Aβ) levels. In-vitro knock-down of LRRTM3 was previously shown to decrease secreted Aβ, although the mechanism of this is unclear. In SH-SY5Y cells overexpressing APP and transiently transfected with LRRTM3 alone or with BACE1, we showed that LRRTM3 co-localizes with both APP and BACE1 in early endosomes, where BACE1 processing of APP occurs. Additionally, LRRTM3 co-localizes with APP in primary neuronal cultures from Tg2576 mice transduced with LRRTM3-expressing adeno-associated virus. Moreover, LRRTM3 co-immunoprecipitates with both endogenous APP and overexpressed BACE1, in HEK293T cells transfected with LRRTM3. SH-SY5Y cells with knock-down of LRRTM3 had lower BACE1 and higher CTNNA3 mRNA levels, but no change in APP. Brain mRNA levels of LRRTM3 showed significant correlations with BACE1, CTNNA3 and APP in ∼400 humans, but not in LRRTM3 knock-out mice. Finally, we assessed 69 single nucleotide polymorphisms (SNPs) within and flanking LRRTM3 in 1,567 LOADs and 2,082 controls and identified 8 SNPs within a linkage disequilibrium block encompassing 5′UTR-Intron 1 of LRRTM3 that formed multilocus genotypes (MLG) with suggestive global association with LOAD risk (p = 0.06), and significant individual MLGs. These 8 SNPs were genotyped in an independent series (1,258 LOADs and 718 controls) and had significant global and individual MLG associations in the combined dataset (p = 0.02–0.05). Collectively, these results suggest that protein interactions between LRRTM3, APP and BACE1, as well as complex associations between mRNA levels of LRRTM3, CTNNA3, APP and BACE1 in humans might influence APP metabolism and ultimately risk of AD.© 2013 Lincoln et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
First Observation of the Greisen-Zatsepin-Kuzmin Suppression
The High Resolution Fly's Eye (HiRes) experiment has observed the
Greisen-Zatsepin-Kuzmin suppression (called the GZK cutoff) with a statistical
significance of five standard deviations. HiRes' measurement of the flux of
ultrahigh energy (UHE) cosmic rays shows a sharp suppression at an energy of eV, consistent with the expected cutoff energy. We observe the
``ankle'' of the cosmic-ray energy spectrum as well, at an energy of eV. We describe the experiment, data collection, analysis, and
estimate the systematic uncertainties. The results are presented and the
calculation of the statistical significance of our observation is described.Comment: 4 pages, 3 figures, accepted by and to appear in PR
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