4,791 research outputs found
Characterizing the pulsations of the ZZ Ceti star KUV 02464+3239
We present the results on period search and modeling of the cool DAV star KUV
02464+3239. Our observations resolved the multiperiodic pulsational behaviour
of the star. In agreement with its position near the red edge of the DAV
instability strip, it shows large amplitude, long period pulsation modes, and
has a strongly non-sinusoidal light curve. We determined 6 frequencies as
normal modes and revealed remarkable short-term amplitude variations. A
rigorous test was performed for the possible source of amplitude variation:
beating of modes, effect of noise, unresolved frequencies or rotational
triplets. Among the best-fit models resulting from a grid search, we selected 3
that gave l=1 solutions for the largest amplitude modes. These models had
masses of 0.645, 0.650 and 0.680 M_Sun. The 3 `favoured' models have M_H
between 2.5x10^-5 - 6.3x10^-6 M_* and give 14.2 - 14.8 mas seismological
parallax. The 0.645 M_Sun (11400 K) model also matches the spectroscopic log g
and T_eff within 1 sigma. We investigated the possibility of mode trapping and
concluded that while it can explain high amplitude modes, it is not required.Comment: 11 pages, 8 figures, accepted for publication in MNRA
Sudbury project (University of Muenster-Ontario Geological Survey): Field studies 1984-1989 - summary of results
In cooperation between the Ontario Geological Survey and the Institute of Geology and Institute of Planetology, geological, petrological, and geochemical studies were carried out on impact-related phenomena of the Sudbury structure during the last decade. The main results of the field studies are briefly reviewed. Footwall rocks, sublayer, and lower sections of the Sudbury Igneous Complex (SIC) were mainly mapped and sampled in the northern (Levack Township) and western (Trillabelle and Sultana Properties) parts of the north range. Within these mapping areas Sudbury Breccias (SB) and Footwall Breccias (FB) were studied; SB were also investigated along extended profiles beyond the north and south ranges up to 55 km from the SIC. The Onaping Formation (OF) and the upper section of the SIC were studied both in the north range (Morgan and Dowling Townships) and in the southern east range (Capreol and McLennan Townships)
Additive benefit of higher testosterone levels and vitamin D plus calcium supplementation in regard to fall risk reduction among older men and women
Summary: Higher physiologic testosterone levels among community dwelling older men and women may protect against falls, and this benefit may be further increased among those taking additional vitamin D plus calcium. Introduction: The aim of this study is to investigate sex hormone levels and fall risk in older men and women. Methods: One hundred and ninety-nine men and 246 women age 65+ living at home were followed for 3years after baseline assessment of sex hormones. Analyses controlled for several covariates, including baseline 25-hydroxyvitamin D, sex hormone binding globulin, and vitamin D plus calcium treatment (vitD+cal). Results: Compared to the lowest quartile, men and women in the highest quartile of total testosterone had a decreased odds of falling (men: OR = 0.22; 95% CI [0.07,0.72]/ women: OR = 0.34; 95% CI [0.14,0.83]); if those individuals also took vitD+cal, the fall reduction was enhanced (men: OR = 0.16; 95% CI [0.03,0.90] / women: OR = 0.15; 95% CI [0.04,0.57]). Similarly, women in the top quartile of dihydroepiandrosterone sulfate (DHEA-S) had a lower risk of falling (OR = 0.39; 95% CI [0.16,0.93]). Other sex hormones and SHBG did not predict falling in men or women. Conclusions: Higher testosterone levels in both genders and higher DHEA-S levels in women predicted a more than 60% lower risk of falling. With vitD+cal, the anti-fall benefit of higher physiologic testosterone levels is enhanced from 78% to 84% among men and from 66% to 85% among wome
A simple stress test of experimenter demand effects
As a stress test of experimenter demand effects, we run an experiment where subjects can physically destroy coupons awarded to them. About one subject out of three does. Giving money back to the experimenter is possible in a separate task but is more consistent with an experimenter demand effect than an explanation based on altruism towards the experimenter. A measure of sensitivity to social pressure helps predict destruction when social information is provided
Optically probing symmetry breaking in the chiral magnet Cu2OSeO3
We report on the linear optical properties of the chiral magnet Cu2OSeO3,
specifically associated with the absence of inversion symmetry, the chiral
crystallographic structure, and magnetic order. Through spectroscopic
ellipsometry, we observe local crystal-field excitations below the
charge-transfer gap. These crystal-field excitations are optically allowed due
to the lack of inversion symmetry at the Cu sites. Optical polarization
rotation measurements were used to study the structural chirality and magnetic
order. The temperature dependence of the natural optical rotation, originating
in the chiral crystal structure, provides evidence for a finite
magneto-electric effect in the helimagnetic phase. We find a large
magneto-optical susceptibility on the order of V(540nm)~10^4 rad/(T*m) in the
helimagnetic phase and a maximum Faraday rotation of ~165deg/mm in the
ferrimagnetic phase. The large value of V can be explained by considering spin
cluster formation and the relative ease of domain reorientation in this
metamagnetic material. The magneto-optical activity allows us to map the
magnetic phase diagram, including the skyrmion lattice phase. In addition to
this, we probe and discuss the nature of the various magnetic phase transitions
in Cu2OSeO3.Comment: 9 pages, 10 figure
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