9,762 research outputs found
Heat capacity anomaly at the quantum critical point of the Transverse Ising Magnet CoNb_2O_6
The transverse Ising magnet Hamiltonian describing the Ising chain in a
transverse magnetic field is the archetypal example of a system that undergoes
a transition at a quantum critical point (QCP). The columbite CoNbO is
the closest realization of the transverse Ising magnet found to date. At low
temperatures, neutron diffraction has observed a set of discrete collective
spin modes near the QCP. We ask if there are low-lying spin excitations
distinct from these relatively high energy modes. Using the heat capacity, we
show that a significant band of gapless spin excitations exists. At the QCP,
their spin entropy rises to a prominent peak that accounts for 30 of the
total spin degrees of freedom. In a narrow field interval below the QCP, the
gapless excitations display a fermion-like, temperature-linear heat capacity
below 1 K. These novel gapless modes are the main spin excitations
participating in, and affected, by the quantum transition.Comment: 14 pages total, 8 figure
Manipulating target size influences perceptions of success when learning a dart-throwing skill but does not impact retention
Positive feedback or experiences of success during skill acquisition have been shown to benefit motor skill learning. In this study, our aim was to manipulate learners’ success perceptions through a minor adjustment to goal criterion (target size) in a dart-throwing task. Two groups of novice participants practiced throwing at a large (easy) or a small (difficult) target from the same distance. In reference to the origin/centre of the target, the practice targets were alike in objective difficulty and indeed participants in both groups were not different in their objective practice performance (i.e. radial error from the centre). Although the groups experienced markedly different success rates, with the large target group experiencing more hits and reporting greater confidence (or self-efficacy) than the small target group, these practice effects were not carried into longer-term retention, which was assessed after a one-week delay. For success perceptions to moderate or benefit motor learning, we argue that unambiguous indicators of positive performance are necessary, especially for tasks where intrinsic feedback about objective error is salient
CFD Simulation of Low Reynolds-number Turbulence Models in Coral Thermal Microenvironment
The increasing frequency and severity of mass bleaching events in the past few decades has raised considerable concerns. Here we report on the numerical simulations of Low Reynolds turbulence models coral microenvironments to determine surface temperature rise in reef corals and test whether our model is capable to estimate of the extent of warming likely to be en-countered in the nature during calm conditions. The Computational Fluid Dynamics (CFD) simulation uses the OpenFOAM CFD libraries to implement a steady-state turbulent flow porous medium model, with heat transfer accounted for using a transport equation for temperature. We validated the model using controlled laboratory experiment observations
Limits, Transparency, and Board Independence Against Tax Avoidance
Taxes are levied by the government primarily for public service purposes (De Leon & De Leon, 2016).However, the high tax rates and narrow tax base imposed in the Philippines become burdensome for taxpayers and also decrease total government revenue collections (Diokno, 2008). It is shown in this study that foreign ownership and customer concentration both increase the levels of corporate tax avoidance practiced by firms while board independence decreases the same. Hence, we do not support the government’s plan to ease foreign ownership restrictions through the amendment of the Constitution (Romualdez, 2017) because easing the current restrictions may entail decreased government revenue. Additionally, we recommend that the International Accounting Standards Board (IASB) strengthen the enforcement of the International Financial Reporting Standards 8 (IFRS 8). In this case, increased transparency in disclosures is needed to help the government prevent the use of tax havens by major conglomerates. Lastly, we support the Securities and Exchange Commission’s (SEC) recommendation to have a certain minimum threshold on the proportion of independent directors in PSElisted firms on the basis that doing so will reduce levels of tax avoidance within these firms
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