1,653 research outputs found
Incommensurate Magnetic Order in the Kagome Metal GdVSn
We characterize the magnetic ground state of the topological kagome metal
GdVSn via resonant X-ray diffraction. Previous magnetoentropic studies
of GdVSn suggested the presence of a modulated magnetic order distinct
from the ferromagnetism that is easily polarized by the application of a
magnetic field. Diffraction data near the Gd- edge directly resolve a
-axis modulated spin structure order on the Gd sublattice with an
incommensurate wave vector that evolves upon cooling toward a partial lock-in
transition. While equal moment (spiral) and amplitude (sine) modulated spin
states can not be unambiguously discerned from the scattering data, the overall
phenomenology suggests an amplitude modulated state with moments predominantly
oriented in the -plane. Comparisons to the ``double-flat" spiral state
observed in Mn-based MnSn kagome compounds of the same structure
type are discussed.Comment: 5 pages, 4 figure
Recommended from our members
The Cost of Transmission for Wind Energy: A Review of Transmission Planning Studies
The rapid development of wind power that the United States has experienced over the last several years has been coupled with a growing concern that wind development will require substantial additions to the nation's transmission infrastructure. Transmission is particularly important for wind power due to the locational dependence of wind resources, the relatively low capacity factor of wind plants, and the mismatch between the short lead time to build a new wind project and the longer lead time often needed to plan, permit, and construct transmission. It is clear that institutional issues related to transmission planning, siting, and cost allocation will pose major obstacles to accelerated wind power deployment, but also of concern is the potential cost of this infrastructure build out. Simply put, how much extra cost will society bear to deliver wind power to load centers? Without an answer to this question, there can be no consensus on whether or not the cost of developing transmission for wind will be a major barrier to further wind deployment, or whether the institutional barriers to transmission expansion are likely to be of more immediate concern. In this report, we review a sample of 40 detailed transmission studies that have included wind power. These studies cover a broad geographic area, and were completed from 2001-2008. Our primary goal in reviewing these studies is to develop a better understanding of the transmission costs needed to access growing quantities of wind generation. A secondary goal is to gain a better appreciation of the differences in transmission planning approaches in order to identify those methodologies that seem most able to estimate the incremental transmission costs associated with wind development. Finally, we hope that the resulting dataset and discussion might be used to inform the assumptions, methods, and results of higher-level assessment models that are sometimes used to estimate the cost of wind deployment (e.g. NEMS and WinDS). The authors and general location of the 40 detailed transmission studies included in our review are illustrated in Figure ES-1. As discussed in the body of the report, these studies vary considerably in scope, authorship, objectives, methodology, and tools. Though we recognize this diversity and are cognizant that comparisons among these studies are therefore somewhat inappropriate, we nonetheless emphasize such simple comparisons in this report. We do so in order to improve our understanding of the range of transmission costs needed to access greater quantities of wind, and to highlight some of the drivers of those costs. In so doing, we gloss over many important details and differences among the studies in our sample. In emphasizing simple comparisons, our analysis focuses primarily on the unit cost of transmission implied by each of the studies. The unit cost of transmission for wind in $/kW terms on a capacity-weighted basis is estimated by simply dividing the total transmission cost in a study by the total amount of incremental generation capacity (wind and non-wind) modeled in that study. In so doing, this metric assumes that within any individual study all incremental generation capacity imposes transmission costs in proportion to its nameplate capacity rating. The limitations to this approach are described in some detail in the body of the report
Effects of Moderate Sleep Restriction During 8-week Calorie Restriction on Lipoprotein Particles and Glucose Metabolism
Study Objectives
This study examined how glucose, glucose regulatory hormones, insulin sensitivity, and lipoprotein subclass particle concentrations and sizes change with sleep restriction during weight loss elicited by calorie restriction.
Methods
Overweight or obese adults were randomized into an 8-week calorie restriction intervention alone (CR, n = 12; 75% female; body mass index = 31.4 ± 2.9 kg/m2) or combined with sleep restriction (CR+SR, n = 16; 75% female; body mass index = 34.5 ± 3.1 kg/m2). Participants in both groups were given the same instructions to reduce calorie intake. Those in the CR+SR group were instructed to reduce their habitual time-in-bed by 30–90 minutes 5 days each week with 2 ad libitum sleep days. Fasting venous blood samples were collected at pre- and post-intervention.
Results
Differential changes were found between the two groups (p = 0.028 for group × time interaction) in glucagon concentration, which decreased in the CR group (p = 0.016) but did not change in CR+SR group. Although changes in mean HDL particle (HDL-P) size and visfatin concentration were not statistically different between groups (p = 0.066 and 0.066 for group×time interaction, respectively), mean HDL-P size decreased only in the CR+SR group (Cohen’s d = 0.50, p = 0.022); visfatin concentrations did not change significantly in either group but appeared to decrease in the CR group (Cohen’s d = 0.67, p = 0.170) but not in the CR+SR group (Cohen’s d = 0.43, p = 0.225).
Conclusion
These results suggest that moderate sleep restriction, despite the presence of periodic ad libitum sleep, influences lipoprotein subclass particles and glucose regulation in individuals undergoing calorie restriction.
Clinical trial registration: ClinicalTrials.gov (NCT02413866, Weight Outlooks by Restriction of Diet and Sleep
Motivation profiles in sport: A self-determination theory perspective
The present study examined the link between motivation profiles among adult sports participants and the outcomes of enjoyment, effort, positive and negative affect, attitude toward sport participation, intention to continue sport participation, satisfaction, and persistence in sport. Two samples of participants (n = 590 and n = 555) completed the Sport Motivation Scale and a range of self-report measures to assess the outcome variables. Exploratory cluster analyses applied to Sample 1 and confirmatory cluster analysis applied to Sample 2 identified two clusters of sport participants. The first comprised participants with high scores on both non self-determined and self-determined motives. The second comprised participants with high scores on self-determined motives but low scores on non self- determined motives. Participants in the first cluster scored higher on all outcome variables. The results are discussed with reference to a more in-depth understanding of the motivation dynamics of sport participation based on Self-Determination Theory
Chemical speciation of nanoparticles surrounding metal-on-metal hips.
Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr(3+), with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed
Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant cavity by seed-free electrochemical synthesis
Workbench-size particle accelerators, enabled by Nb3Sn-based superconducting
radio-frequency (SRF) cavities, hold the potential of driving scientific
discovery by offering a widely accessible and affordable source of high-energy
electrons and X-rays. Thin-film Nb3Sn RF superconductors with high quality
factors, high operation temperatures, and high-field potentials are critical
for these devices. However, surface roughness, non-stoichiometry, and
impurities in Nb3Sn deposited by conventional Sn-vapor diffusion prevent them
from reaching their theoretical capabilities. Here we demonstrate a seed-free
electrochemical synthesis that pushes the limit of chemical and physical
properties in Nb3Sn. Utilization of electrochemical Sn pre-deposits reduces the
roughness of converted Nb3Sn by five times compared to typical vapor-diffused
Nb3Sn. Quantitative mappings using chemical and atomic probes confirm improved
stoichiometry and minimized impurity concentrations in electrochemically
synthesized Nb3Sn. We have successfully applied this Nb3Sn to the large-scale
1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at
multiple operation temperatures, notably lower than vapor-diffused cavities.
Our smooth, homogeneous, high-purity Nb3Sn provides the route toward high
efficiency and high fields for SRF applications under helium-free cryogenic
operations
Perceptions of animal physiotherapy amongst Irish veterinary surgeons
The aim of this study was to investigate veterinary surgeons' perceptions, knowledge and use of animal physiotherapy in the Republic of Ireland. A questionnaire was developed and sent to 200 veterinary surgeons, of which 97 were returned. Results indicated that 77 (79%) of respondents were aware of animal physiotherapists. Common sources of information included veterinary colleagues, owners and professional journals, with physiotherapists themselves and undergraduate training being less commonly cited. Awareness of animal physiotherapy was greatest amongst those working in equine practice (χ2 = 5.7, df 1, p = 0.017); they were more knowledgeable about its techniques (t = 2.806, df 75, p = 0.006) and more likely to refer (χ2 = 48.36, df 1, p = 0.0001). Seventy-four respondents (96%) thought that more research was necessary to increase the evidence base for animal physiotherapy. If this branch of physiotherapy is to develop, there needs to be increased interaction and co-operation between veterinary surgeons and chartered animal physiotherapists
The Relationship Between HR Practices and Firm Performance: Examining Causal Order
Significant research attention has been devoted to examining the relationship between HR practices and firm performance, and the research support has assumed HR as the causal variable. Using data from 45 business units (with 62 data points), this study examines how measures of HR practices correlate with past, concurrent, and future operational performance measures. The results indicate that correlations with performance measures at all three times are both high and invariant, and that controlling for past or concurrent performance virtually eliminates the correlation of HR with future performance. Implications are discussed
- …