Hartree-Fock theory with a self-generated magnetic field

We prove the existence of a ground state within the Hartree-Fock theory for atoms and molecules, in the presence of self-generated magnetic fields, with and without direct spin coupling. The ground state exists provided that the total charge Z of the K nuclei exceeds N, where N is the number of electrons, and, in the spin-polarized case, provided in addition that the nuclear charge is not too high

An efficient multigrid strategy for large-scale molecular mechanics optimization

Static mechanical properties of materials require large-scale nonlinear optimization of the molecular mechanics model under various controls. This paper presents an efficient multigrid strategy to solve such problems. This strategy approximates solutions on grids in a quasi-atomistic and inexact manner, transfers solutions on grids following a coarse-to-fine (oneway) schedule, and finds physically relevant minimizers with linear scaling complexity. Compared to the full multigrid method which has the same complexity, the prefactor of this strategy is orders of magnitude smaller. Consequently, the required CPU time of this strategy is orders of magnitude smaller than that of the full multigrid method, and is smaller than that of the brute-force optimization for systems with more than 200,000 atoms. Considerable savings are found if the number of atoms becomes even larger due to the super-linear scaling complexity of the brute-force optimization. For systems with 1,000,000 atoms (over three million degrees of freedom), on average a more than 70% reduction of CPU time is observed regardless of the type of defects, including vacancies, dislocations, and cracks. In addition, linear scalability of the proposed strategy is tested in the presence of a dislocation pair for systems with more than 100 million atoms (over 400 million degrees of freedom)

Magnetic domain-twin boundary interactions in Ni-Mn-Ga

The stress required for the propagation of twin boundaries in a sample with fine twins increases monotonically with ongoing deformation. In contrast, for samples with a single twin boundary, the stress exhibits a plateau over the entire twinning deformation range. We evaluate the twin boundary and magnetic domain boundary interactions for increasing twin densities. As the twinned regions get finer, these interaction regions result in additional magnetic domains that form magnetoelastic defects with high magnetostress concentrations. These magnetoelastic defects act as obstacles for twinning disconnections and, thus, harden the material. Whereas in a low twin density microstructure, these high-energy concentrations are absent or dilute and their effectiveness is reduced by the synergistic action of many twinning disconnections. Therefore, with increasing twin density, the interaction of twin boundary and magnetic domain boundaries reduces the twin boundary mobility. The defect strength has a distribution such that twinning disconnections overcome soft obstacles first and harder obstacles with ongoing deformation. The width of the distribution of obstacle strength and the density of obstacles increase with increasing twin density and, thus, the hardening coefficient increases with increasing twin density

Mean-field dynamics of the spin-magnetization coupling in ferromagnetic materials: Application to current-driven domain wall motions

In this paper, we present a mean-field model of the spin-magnetization coupling in ferromagnetic materials. The model includes non-isotropic diffusion for spin dynamics, which is crucial in capturing strong spin-magnetization coupling. The derivation is based on a moment closure of the quantum spinor dynamics coupled to magnetization dynamics via the Landau-Lifchitz-Gilbert equation and the spin-transfer torque. The method is general and systematic, and can be used to study spin-orbit coupling as well. The form of the non-isotropic diffusion is generic, i.e., independent of the closure assumptions. Fully 3-D numerical simulation is implemented and applied to predict current-driven domain wall motions. It shows a non-linear dependence of the wall speed on the current density, which agrees with the experiments

Realistic Neutrino Opacities for Supernova Simulations With Correlations and Weak Magnetism

Advances in neutrino transport allow realistic neutrino interactions to be incorporated into supernova simulations. We add tensor couplings to relativistic RPA calculations of neutrino opacities. Our results reproduce free-space neutrino-nucleon cross sections at low density, including weak magnetism and recoil corrections. In addition, our opacities are thermodynamically consistent with relativistic mean field equations of state. We find antineutrino mean free paths that are considerably larger then those for neutrinos. This difference depends little on density. In a supernova, this difference could lead to an average energy of $\bar\nu_\mu$ that is larger than that for $\nu_\mu$ by an amount that is comparable to the energy difference between $\nu_\mu$ and $\bar\nu_e$Comment: 15 pages, 10 figures, submitted to PRC, minor changes to figs. (9,10

A Mean-field model for spin dynamics in multilayered ferromagnetic media

In this paper, we develop a mean-field model for describing the dynamics of spintransfer torque in multilayered ferromagnetic media. Specifically, we use the techniques of Wigner transform and moment closure to connect the underlying physics at different scales and reach a macroscopic model for the dynamics of spin coupled with the magnetization within the material. This provides a further understanding of the linear response model proposed by Zhang, Levy, and Fert [Phys. Rev. Lett., 88 (2002), 236601], and in particular we get an extra relaxation term which helps to stabilize the system. We develop efficient numerical methods to overcome the stiffness appearing in this new mean-field model and present several examples to analyze and show its validity

Small and large intestine (II): Inflammatory bowel disease, short bowel syndrome, and malignant tumors of the digestive tract

The small intestine is key in the digestion and absorption of macro and micronutrients. The large intestine is essential for the absorption of water, to allow adequate defecation, and to har-bor intestinal microbiota, for which their nutritional role is as important as it is unknown. This article will describe the causes and consequences of malnutrition in patients with inflammatory bowel diseases, the importance of screening and replacement of micronutrient deficits, and the main indi-cations for enteral and parenteral nutrition in these patients. We will also discuss the causes of short bowel syndrome, a complex entity due to anatomical or functional loss of part of the small bowel, which can cause insufficient absorption of liquid, electrolytes, and nutrients and lead to complex management. Finally, we will review the causes, consequences, and management of malnutrition in patients with malignant and benign digestive tumors, including neuroendocrine tumors (present not only in the intestine but also in the pancreas). © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Analysis of Different Uncertainty Activation Cross Section Data Libraries for LWR, ads and demo Neutron Spectra

This work is aimed to present the main differences of nuclear data uncertainties among three different nuclear data libraries: EAF-2007, EAF-2010 and SCALE-6.0, under different neutron spectra: LWR, ADS and DEMO (fusion

Contribution to ehtno-genetic chatacterisation of anandalusian canine dog racial group

We are analysing a sample of 53 animals (16 males and 37 females) of Andalusian mouse hunter dogs or caves dog, with a view to obtain their ethnogenetic characterisation. From our results we have concluded that this population is a racial group presenting a great homogeneity in the variables and zoometric indexes studied, as in the phaneroptical aspects. Their morphology is as a small format, probably elipometrics, with proportional leg length, brevilineous cephalic and body proportions. This population present a three-coloured coat, generally white colour on the body and “black and tan” on the head; the hair is short and smooth, the mucosae is black and the iris brown. With respect the bite, the most frequent are the tweezers form and the scissors, also in few animals we have found the absence of premolars.Se analiza una muestra de perros ratoneros o bodegueros compuesta por 53 ejemplares de los cuales 16 eran machos y 37 hembras, con objeto de lograr una caracterización etnogenética. De los resultados obtenidos concluimos que se trata de una agrupación racial que presenta gran homogeneidad tanto en las variables e índices zoométricos estudiados como en los aspectos fanerópticos. Morfológicamente se trata de animales de formato pequeño, posiblemente elipométricos, ni lejos ni cerca de tierra, y de proporciones braquicéfalas y brevilíneas en cuanto a sus proporciones cefálicas y corporales respectivamente. Fanerópticamente esta población presenta una capa tricolor, generalmente blanco en el cuerpo y negro-fuego en la cabeza, el pelo corto y liso, la pigmentación de las mucosas negras y el iris castaño. En cuanto a la mordida los tipos más frecuentes son en tijera y pinza, y en un escaso número de ejemplares existe ausencia de premolares

EVALUATION OF THE COST-EFFECTIVENESS OF GRID-CONNECTED PHOTOVOLTAIC SOLAR ENERGY IN WINERIES

The objective of this study was to analyze the cost-effectiveness of photovoltaic (PV) solar energy in wineries. The factors analysed were solar radiation, cost of PV installation, prices in the public electricity grid, size of the winery, power of installed panels, influence of the decreased consumption during weekends, and seasonality in the consumption. The study has been based on the European TESLA project, in which 39 energy audits were carried out in wineries in four European countries. A winery of 30,000 hL/year was characterized as a representative winery. The results showed that seasonality was key in the profitability of the system for self-consumption, related to the optimum power to be installed of PV. It was recommended to install, as an optimal PV power, the stable electrical power that is demanded in the daytime period. Optimizing the installed power of PV panels in the representative winery, the percentage of electrical energy consumption covered by photovoltaic energy varied between 16% and 22%. The percentage of the cost of electric energy covered varied between 18% and 24%, with payback values between 18 years (3.1 peak sun hours of solar radiation -PSH) and 10 years (5.6 peak sun hours of solar radiation - PSH). All the factors involved were analyzed