Effect of Dzyaloshinski-Moriya interaction on spin-polarized neutron scattering

For magnetic materials containing many lattice imperfections (e.g., nanocrystalline magnets), the relativistic Dzyaloshinski-Moriya (DM) interaction may result in nonuniform spin textures due to the lack of inversion symmetry at interfaces. Within the framework of the continuum theory of micromagnetics, we explore the impact of the DM interaction on the elastic magnetic small-angle neutron scattering (SANS) cross section of bulk ferromagnets. It is shown that the DM interaction gives rise to a polarization-dependent asymmetric term in the spin-flip SANS cross section. Analysis of this feature may provide a means to determine the DM constant.Comment: 10 pages, 7 figure

Rotational Preference in the Domestic Cat: Relationship to Temperament and Behaviors

Rotational preference, an animal’s preferred turning direction as it moves about with free choice, has been assessed in humans and rodents. Studies have shown that those with a right turning preference are more susceptible to developing learned helplessness, and less likely to act according to Gray\u27s Behavioral Approach System than those who prefer to turn to the left. In the present study, rotational preference was assessed in twenty-nine adult male cats (Felis silvestris catus). Rotational preference was compared to the results of two assessments in a within-subjects design. The first was the Feline Temperament Profile (Lee, Zeglen, Ryan, & Hines, 1983) which was administered by the experimenter. The second was a Cat Behavior Questionnaire which was completed by the cats\u27 owners. The proportion of right turns emitted by the cats was negatively correlated with the number of approach behaviors measured in the temperament test and behavior questionnaire (r = -.591, p =.001). This finding supports studies of rotational preference and behavior with other species, as well as the hypothesized neurochemical basis of reward-seeking behavior (Abwender & Pusateri,2005)

Preconception care: it’s never too early

The preconception window has been recognized as one of the earliest sensitive windows of human development, and interventions that focus on this period have the potential to affect not only pregnancy but long term outcomes as well. The journal Reproductive Health has published a supplement entitled ‘Preconception Interventions’ which includes a series of systematic reviews regarding the impact of public health interventions during the preconception period on maternal and child health. These articles describe the role that poor preconception health plays in creating health disparities across the globe. The reviews highlight our current understanding (or lack thereof) regarding how both maternal and paternal preconception health and knowledge shapes the long-term health of not only children, but of families, communities, and nations. Researchers and healthcare workers should take particular note of these interventions, as the preconception time period may be as important as the pregnancy and post-pregnancy periods, and is critical in terms of bridging the gap in the continuum of care, particularly for adolescents.Fil: Mumford, Sunni L.. National Institutes of Health; Estados UnidosFil: Michels, Kara A.. National Institutes of Health; Estados UnidosFil: Salaria, Natasha. BioMed Central; Reino UnidoFil: Valanzasca, Pilar. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Belizan, Jose. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A semi-analytical approach to molecular dynamics

Despite numerous computational advances over the last few decades, molecular dynamics still favors explicit (and thus easily-parallelizable) time integrators for large scale numerical simulation. As a consequence, computational efficiency in solving its typically stiff oscillatory equations of motion is hampered by stringent stability requirements on the time step size. In this paper, we present a semi-analytical integration scheme that offers a total speedup of a factor 30 compared to the Verlet method on typical MD simulation by allowing over three orders of magnitude larger step sizes. By efficiently approximating the exact integration of the strong (harmonic) forces of covalent bonds through matrix functions, far improved stability with respect to time step size is achieved without sacrificing the explicit, symplectic, time-reversible, or fine-grained parallelizable nature of the integration scheme. We demonstrate the efficiency and scalability of our integrator on simulations ranging from DNA strand unbinding and protein folding to nanotube resonators

Lie Symmetry Analysis for Cosserat Rods

We consider a subsystem of the Special Cosserat Theory of Rods and construct an explicit form of its solution that depends on three arbitrary functions in (s,t) and three arbitrary functions in t. Assuming analyticity of the arbitrary functions in a domain under consideration, we prove that the obtained solution is analytic and general. The Special Cosserat Theory of Rods describes the dynamic equilibrium of 1-dimensional continua, i.e. slender structures like fibers, by means of a system of partial differential equations.Comment: 12 Pages, 1 Figur