Electromagnetic fields induced by an electric charge near a Weyl semimetal

[EN] Weyl semimetals (WSM) are a new class of topological materials that exhibit a bulk Hall effect and a chiral magnetic effect. The topological contribution of these unusual electromagnetic responses can be characterized by an axion term θE·B with space and time dependent axion angle θ(r,t). In this paper we compute the electromagnetic fields produced by an electric charge near a topological Weyl semimetal with two Weyl nodes, in the equilibrium state, at zero electric chemical potential, and with broken time-reversal symmetry. We find that, as in ordinary metals and dielectrics, outside the WSM the electric field is mainly determined by the optical properties of the material. The magnetic field is, on the contrary, of topological origin due to the magnetoelectric effect of topological phases. We show that the magnetic field exhibits an interesting behavior above the WSM as compared with that induced above a topological insulator: the field lines begin at the surface and then end at the surface (but not at the same point). This distinctive behavior of the magnetic field is an experimentally observable signature of the anomalous Hall effect in the bulk of the WSM. We discuss two experimental setups for testing our predictions of the induced magnetic field.We thank Alberto Cortijo for useful comments and suggestions, and also to the anonymous referees for their recommendations. A.M. was supported by the CONACyT postdoctoral Grant No. 234774. L.F.U. has been supported in part by the project CONACyT (México) No. 237503. M.C. has been partially supported by UNAB DGID under Grant No. DI-33-17/RG and wishes to thank A. Martín-Ruiz and L. F. Urrutia at Instituto de Ciencias Nucleares, UNAM for the kind hospitality of throughout the preparation of the manuscript

Heat Stress and Injury Prevention Practices During Summer High School Football Training in South Texas

Int J Exerc Sci 3(2) : 55-63, 2010. The purpose was to describe practice conditions influencing the risk of heat stress to athletes in summer football training in South Texas high schools, and to compare these conditions to ACSM recommendations for heat stress/injury risk reduction in this population. Thirty (N=30) high school summer football practices were observed. Wet bulb globe temperature (WBGT) was measured before/after practices and practices were observed for: duration/ structure; athlete clothing; and rest break frequency/duration/content. Practices averaged 125+31 min and WBGT (pre- to post-practice) was 29.7+2.1°C to 31.2+2.2°C for morning, and 31.2+1.6°C to 28.9+1.2°C for evening practices. Most practices included contact (93%), and a majority were full-contact (53%). Most athletes wore full pads (83%) and medium/dark colored clothing (73%). Outside of scheduled breaks athletes removed helmets (63%), sat/knelt (63%), and had access to fluid (90%). Athletic trainers were present at 93% of the practices. A typical practice had 3 rest breaks, each lasting approximately 5 min. During breaks, athletes were provided fluid (93%), removed helmets (89%), and sat/knelt (76%), but were rarely provided shade (2%). While none of the practice sessions were conducted in conditions warranting the cancellation of outside activity (WBGT\u3e33.1°C), the environmental data confirms that this region presents athletes with a very high risk of heat stress/injury. While a majority of the schools were taking many of the precautionary measures recommended by ACSM, many of the guidelines were not being followed. Governing bodies of high school athletics need to encourage compliance with recommendations for the reduction of heat stress/injury in this population

Economics Students: Self-Selected in Preferences and Indoctrinated in Beliefs

There is much debate as to why economics students display more self-interested behavior than other students: whether homo economicus self-select into economics or students are instead “indoctrinated” by economics learning, and whether these effects impact on preferences or beliefs about others’ behavior. Using a classroom survey (n\u3e500) with novel behavioral questions we show that, compared to students in other majors, econ students report being: (i) more self-interested (in particular, less compassionate or averse to advantageous inequality) already in the first year and the difference remains among more senior students; (ii) more likely to think that people will be unwilling to work if unemployment benefits increase (thus, assuming others are motivated primarily by self-interest), but only among senior students. These results suggest self-selection in preferences and indoctrination in beliefs

Strichatz inequalities with weights in Morrey-Campanato classes

We prove some weighted refinements of the classical Strichartz inequalities for initial data in the Sobolev spaces $H^s (R^n)$. We control the weighted $L^2$ –norm of the solution of the free Schrödinger equation when the weight is in a Morrey–Campanato type space adapted to that equation. Our partial positive results are complemented by some necessary conditions based on estimates for certain particular solutions of the free Schrödinger equation

A Note on Weighted Estimates for the Schrödinger Operator

We study two problems closely related to each other. The first one is concerned with some smoothing weighted estimates with weights in a certain Morrey- Campanato spaces, for the solution of the free Schrödinger equation. The second one is a weighed trace inequality.We study two problems closely related to each other. The first one is concerned with some smoothing weighted estimates with weights in a certain Morrey- Campanato spaces, for the solution of the free Schrödinger equation. The second one is a weighed trace inequality

Magnon straintronics in the 2D van der Waals ferromagnet CrSBr from first-principles

The recent isolation of two-dimensional (2D) magnets offers tantalizing opportunities for spintronics and magnonics at the limit of miniaturization. One of the key advantages of atomically-thin materials is their outstanding deformation capacity, which provides an exciting avenue to control their properties by strain engineering. Herein, we investigate the magnetic properties, magnon dispersion and spin dynamics of the air-stable 2D magnetic semiconductor CrSBr ($T_C$ = 146 K) under mechanical strain using first-principles calculations. Our results provide a deep microscopic analysis of the competing interactions that stabilize the long-range ferromagnetic order in the monolayer. We showcase that the magnon dynamics of CrSBr can be modified selectively along the two main crystallographic directions as a function of applied strain, probing the potential of this quasi-1D electronic system for magnon straintronics applications. Moreover, we predict a strain-driven enhancement of $T_C$ considering environmental screening by ~30%, allowing the propagation of spin waves at higher temperatures

Present-day heat flow model of Mars

Until the acquisition of in-situ measurements, the study of the present-day heat flow of Mars must rely on indirect methods, mainly based on the relation between the thermal state of the lithosphere and its mechanical strength, or on theoretical models of internal evolution. Here, we present a first-order global model for the present-day surface heat flow for Mars, based on the radiogenic heat production of the crust and mantle, on scaling of heat flow variations arising from crustal thickness and topography variations, and on the heat flow derived from the effective elastic thickness of the lithosphere beneath the North Polar Region. Our preferred model finds heat flows varying between 14 and 25 mW m−2, with an average value of 19 mW m−2. Similar results (although about ten percent higher) are obtained if we use heat flow based on the lithospheric strength of the South Polar Region. Moreover, expressing our results in terms of the Urey ratio (the ratio between total internal heat production and total heat loss through the surface), we estimate values close to 0.7–0.75, which indicates a moderate contribution of secular cooling to the heat flow of Mars (consistent with the low heat flow values deduced from lithosphere strength), unless heat-producing elements abundances for Mars are subchondritic

Effects of Regulated and Continuous Deficit Irrigation on Growth and Yield of Super High Density Olive orchard in La Rioja (Spain)

This study evaluated four irrigation strategies applied to olive trees (Arbequina cv.) in super high density orchard, inorder to reduce the consumption of water compared to a fully watered control. The most advantageous strategy has beento prevent the water stress of trees by means of the continuous measurement of trunk diameter fluctuations in which theproductive and vegetative variables are not altered with a 31.2 % of average water saving. The production of moderatestress during the pit hardening phase has also been very interesting. Experience shows that trees recover from thismoderate stress (18.9 % average water saving) and their vegetative and productive characteristics turn out to be verysimilar to those of the control treatment.On the contrary, the strategy that has been based on producing water stress throughout the crop, as well as thatwhich produced severe stress during the pit hardening phase have been shown to significantly alter some of thevegetative and production characteristics. It caused a decrease in oil yield of 16% less compared to the Control, whichmight not compensate for the water saved

NDT-Glossary: A MDE Approach for Glossary Generation

This research paper is contextualized within the paradigm of Model-Driven Engineering (MDE) and it is specifically related to NDT. NDT is a methodology included within the MDE paradigm. The aim of this paper is to present a software tool to facilitate the work of requirements engineers during the requirements validation in a software project. The requirements validation activity takes place within the requirements phase of the life cycle in a software project. The developed tool is called NDT-Glossary and it implements an automatic procedure to generate, from the requirements defined in a project developed with the NDT methodology, the first example of the glossary of terms for this project.Ministerio de Educación y Ciencia TIN2007-67843-C06-03Ministerio de Educación y Ciencia TIN2010-20057-C03-0