301 research outputs found
Torque magnetometry studies of new low temperature metamagnetic states in ErNi_{2}B_{2}C
The metamagnetic transitions in single-crystal ErNiBC have been
studied at 1.9 K with a Quantum Design torque magnetometer. The critical fields
of the transitions depend crucially on the angle between applied field and the
easy axis [100]. Torque measurements have been made while changing angular
direction of the magnetic field (parallel to basal tetragonal -planes) in a
wide angular range (more than two quadrants). Sequences of metamagnetic
transitions with increasing field are found to be different for the magnetic
field along (or close enough to) the easy [100] axis from that near the hard
[110] axis. The study have revealed new metamagnetic states in ErNiBC
which were not apparent in previous longitudinal-magnetization and neutron
studies.Comment: 3 pages (4 figs. incl.) reported at 52th Magnetism and Magnetic
Materials Conference, Tampa, Florida, USA, November 200
Torque magnetometry studies of metamagnetic transitions in single-crystal HoNi_{2}B_{2}C and ErNi_{2}B_{2}C at T\approx 1.9 K
The metamagnetic transitions in single-crystal rare-earth nickel borocarbide
HoNi_{2}B_{2}C and ErNi_{2}B_{2}C have been studied at 1.9 K with a Quantum
Design torque magnetometer. The critical fields of the transitions depend
crucially on the angle between applied field and the easy axis [110] for
HoNi_2B_2C and [100] for ErNi_2B_2C. Torque measurements have been made while
changing angular direction of the magnetic field (parallel to basal tetragonal
ab-planes) in a wide angular range (more than two quadrants). The results are
used not only to check and refine the angular diagram for metamagnetic
transitions in these compounnds, but also to find new features of the
metamagnetic states. Among new results for the Ho borocarbide are the influence
of a multidomain antiferromagnetic state, and ``frustrated'' behavior of the
magnetic system for field directions close to the hard axis [100]. Torque
measurements of the Er borocarbide clearly show that the sequence of
metamagnetic transitions with increasing field (and the corresponding number of
metamagnetic states) depends on the angular direction of the magnetic field
relative to the easy axis.Comment: 3pages (4 figs. incl.) reported at 50th Magnetism and Magnetic
Materials Conference, San Jose, CA, USA, 200
A Currency for Offsetting Energy Development Impacts: Horse-Trading Sage-Grouse on the Open Market
Background: Biodiversity offsets provide a mechanism to compensate for unavoidable damages from new energy development as the U. S. increases its domestic production. Proponents argue that offsets provide a partial solution for funding conservation while opponents contend the practice is flawed because offsets are negotiated without the science necessary to backup resulting decisions. Missing in negotiations is a biologically-based currency for estimating sufficiency of offsets and a framework for applying proceeds to maximize conservation benefits. Methodology/Principal Findings: Here we quantify a common currency for offsets for greater sage-grouse (Centrocercus urophasianus) by estimating number of impacted birds at 4 levels of development commonly permitted. Impacts were indiscernible at 1-12 wells per 32.2 km(2). Above this threshold lek losses were 2-5 times greater inside than outside of development and bird abundance at remaining leks declined by -32 to -77%. Findings reiterated the importance of time-lags as evidenced by greater impacts 4 years after initial development. Clustering well locations enabled a few small leks to remain active inside of developments. Conclusions/Significance: Documented impacts relative to development intensity can be used to forecast biological tradeoffs of newly proposed or ongoing developments, and when drilling is approved, anticipated bird declines form the biological currency for negotiating offsets. Monetary costs for offsets will be determined by true conservation cost to mitigate risks such as sagebrush tillage to other populations of equal or greater number. If this information is blended with landscape level conservation planning, the mitigation hierarchy can be improved by steering planned developments away from conservation priorities, ensuring compensatory mitigation projects deliver a higher return for conservation that equate to an equal number of birds in the highest priority areas, provide on-site mitigation recommendations, and provide a biologically based cost for mitigating unavoidable impacts
Investigation of the superconducting energy gap in the compound LuNiBC by the method of point contact spectroscopy: two-gap approximation
It is shown that the two-gap approximation is applicable for describing the
spectra of LuNiBC-Ag point contacts in a wide interval
of temperatures. The values and the temperature dependences of the large and
the small gaps in the plane and in the direction were estimated using
the generalized BTK model and the equations of Beloborodko. In the BCS
extrapolation the critical temperature of the small gap is 10 in the
plane and 14.5 in the direction. The absolute values of the gaps are
and . For the large gaps the
critical temperature coincides with the bulk , , and
their absolute values are very close, being about 3 in both orientations.
In the direction the contributions to the conductivity from the small and
the large gaps remain practically identical up to . In the
plane the contribution from the small gap is much smaller and decreases rapidly
as a temperature rises.Comment: 10 pages, 10 figures, submitted to Fiz. Nizk. Temp. (Low Temp. Phys.
Active Virtual Reality Games Reduce Pain Sensitivity in Young, Healthy Adults
Separately, both physical activity and virtual reality can attenuate pain sensitivity in healthy adults. What is unknown is whether virtual reality combined with physical activity (active virtual reality) could have a greater hypoalgesic effect compared to non-active virtual reality distraction (passive virtual reality engagement).
Objective: The purpose of this study was to determine whether playing physically active virtual reality games exert a greater hypoalgesic effect than a non-active virtual reality game.
Methods: Participants (n = 36) played three different active virtual reality games (Beat Saber, Holopoint, and Hot Squat) and one non-active virtual reality game (Relax Walk) for 15 min on four different visits. During gameplay, participants wore accelerometers on the thigh, wrist, and waist to measure movement intensity and quantity. Pressure pain thresholds were measured on the forearm and thigh immediately prior to gameplay (pretest) and immediately following each gaming bout (posttest).
Results: Analysis of the accelerometer data indicated that Hot Squat elicited greater whole-body and lower body moderate to vigorous physical activity compared to the other games. The ANOVA revealed an overall hypoalgesic effect of the virtual reality games on the forearm, regardless of game type. Results also showed a significant hypoalgesic effect on the thigh following gameplay for Hot Squat, Holopoint, and Relax Walk VR. The magnitude of pain reduction was significantly greater during Hot Squat compared to the other games.
Conclusion: Virtual reality gameplay exerted a hypoalgesic effect on experimental pressure pain. Additionally, the data provided evidence of a potential enhanced hypoalgesic effect of physically active virtual reality compared to non-active VR on pressure pain sensitivity
Variation in Coral Thermotolerance Across a Pollution Gradient Erodes as Coral Symbionts Shift to More Heat-Tolerant Genera
Phenotypic plasticity is one mechanism whereby species may cope with stressful environmental changes associated with climate change. Reef building corals present a good model for studying phenotypic plasticity because they have experienced rapid climate-driven declines in recent decades (within a single generation of many corals), often with differential survival among individuals during heat stress. Underlying differences in thermotolerance may be driven by differences in baseline levels of environmental stress, including pollution stress. To examine this possibility, acute heat stress experiments were conducted on Acropora hyacinthus from 10 sites around Tutuila, American Samoa with differing nutrient pollution impact. A threshold-based heat stress assay was conducted in 2014 and a ramp-hold based assay was conducted in 2019. Bleaching responses were measured by assessing color paling. Endosymbiont community composition was assessed at each site using quantitative PCR. RNA sequencing was used to compare differences in coral gene expression patterns prior to and during heat stress in 2019. In 2014, thermotolerance varied among sites, with polluted sites holding more thermotolerant corals. These differences in thermotolerance correlated with differences in symbiont communities, with higher proportions of heat-tolerant Durusdinium found in more polluted sites. By 2019, thermotolerance varied less among sites, with no clear trend by pollution level. This coincided with a shift toward Durusdinium across all sites, reducing symbiont community differences seen in 2014. While pollution and symbiont community no longer could explain variation in thermotolerance by 2019, gene expression patterns at baseline levels could be used to predict thermotolerance thresholds. These patterns suggest that the mechanisms underlying thermotolerance shifted between 2014 and 2019, though it is possible trends may have also been affected by methodological differences between heat stress assays. This study documents a shift in symbiont community over time and captures potential implications of that shift, including how it affects variation in thermotolerance among neighboring reefs. This work also highlights how gene expression patterns could help identify heat-tolerant corals in a future where most corals are dominated by Durusdinium and symbiont-driven thermotolerance has reached an upper limit
Effects of Caffeine on the Muscular Endurance, Perceived Pain, and Effort of Resistance Trained Women
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Coral calcification mechanisms in a warming ocean and the interactive effects of temperature and light
Coral calcification mechanisms in a warming ocean and the interactive effects of temperature and light
Point Contact Spectroscopy of Superconducting Gap Anisotropy in Nickel Borocarbide Compound LuNi2B2C
Point contacts are used to investigate the anisotropy of the superconducting
energy gap in LuNi2B2C in the ab plane and along the c axis. It is shown that
the experimental curves should be described assuming that the superconducting
gap is non-uniformly distributed over the Fermi surface. The largest and the
smallest gaps have been estimated by two-gap fitting models. It is found that
the largest contribution to the point-contact conductivity in the c direction
is made by a smaller gap and, in the ab plane by a larger gap. The deviation
from the one-gap BCS model is pronounced in the temperature dependence of the
gap in both directions. The temperature range, where the deviation occurs, is
for the c direction approximately 1.5 times more than in the ab plane. The
\Gamma parameter, allowing quantitatively estimate the gap anisotropy by
one-gap fitting, in c direction is also about 1.5 times greater than in the ab
plane. Since it is impossible to describe satisfactorily such gap distribution
either by the one- or two-gap models, a continuous, dual-maxima model of gap
distribution over the Fermi surface should be used to describe
superconductivity in this material.Comment: 10 pages, 14 Figs, accepted in PR
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