Electron scattering states at solid surfaces calculated with realistic potentials

Scattering states with LEED asymptotics are calculated for a general non-muffin tin potential, as e.g. for a pseudopotential with a suitable barrier and image potential part. The latter applies especially to the case of low lying conduction bands. The wave function is described with a reciprocal lattice representation parallel to the surface and a discretization of the real space perpendicular to the surface. The Schroedinger equation leads to a system of linear one-dimensional equations. The asymptotic boundary value problem is confined via the quantum transmitting boundary method to a finite interval. The solutions are obtained basing on a multigrid technique which yields a fast and reliable algorithm. The influence of the boundary conditions, the accuracy and the rate of convergence with several solvers are discussed. The resulting charge densities are investigated.Comment: 5 pages, 4 figures, copyright and acknowledgment added, typos etc. correcte

Towards Collaborative Conceptual Exploration

In domains with high knowledge distribution a natural objective is to create principle foundations for collaborative interactive learning environments. We present a first mathematical characterization of a collaborative learning group, a consortium, based on closure systems of attribute sets and the well-known attribute exploration algorithm from formal concept analysis. To this end, we introduce (weak) local experts for subdomains of a given knowledge domain. These entities are able to refute and potentially accept a given (implicational) query for some closure system that is a restriction of the whole domain. On this we build up a consortial expert and show first insights about the ability of such an expert to answer queries. Furthermore, we depict techniques on how to cope with falsely accepted implications and on combining counterexamples. Using notions from combinatorial design theory we further expand those insights as far as providing first results on the decidability problem if a given consortium is able to explore some target domain. Applications in conceptual knowledge acquisition as well as in collaborative interactive ontology learning are at hand.Comment: 15 pages, 2 figure

Chromosome mapping: radiation hybrid data and stochastic spin models

This work approaches human chromosome mapping by developing algorithms for ordering markers associated with radiation hybrid data. Motivated by recent work of Boehnke et al. [1], we formulate the ordering problem by developing stochastic spin models to search for minimum-break marker configurations. As a particular application, the methods developed are applied to 14 human chromosome-21 markers tested by Cox et al. [2]. The methods generate configurations consistent with the best found by others. Additionally, we find that the set of low-lying configurations is described by a Markov-like ordering probability distribution. The distribution displays cluster correlations reflecting closely linked loci.Comment: 26 Pages, uuencoded LaTex, Submitted to Phys. Rev. E, [email protected], [email protected]

Monoaminergic integration of diet and social signals in the brains of juvenile spadefoot toads

ABSTRACT Social behavior often includes the production of species-specific signals (e.g. mating calls or visual displays) that evoke context-dependent behavioral responses from conspecifics. Monoamines are important neuromodulators that have been implicated in context-dependent social behavior, yet we know little about the development of monoaminergic systems and whether they mediate the effects of early life experiences on adult behavior. We examined the effects of diet and social signals on monoamines early in development in the plains spadefoot toad (Spea bombifrons), a species in which diet affects the developmental emergence of species recognition and body condition affects the expression of adult mating preferences. To do so, we manipulated the diet of juveniles for 6 weeks following metamorphosis and collected their brains 40 min following the presentation of either a conspecific or a heterospecific call. We measured levels of monoamines and their metabolites using high pressure liquid chromatography from tissue punches of the auditory midbrain (i.e. torus semicircularis), hypothalamus and preoptic area. We found that call type affected dopamine and noradrenaline signaling in the auditory midbrain and that diet affected dopamine and serotonin in the hypothalamus. In the preoptic area, we detected an interaction between diet and call type, indicating that diet modulates how the preoptic area integrates social information. Our results suggest that the responsiveness of monoamine systems varies across the brain and highlight preoptic dopamine and noradrenaline as candidates for mediating effects of early diet experience on later expression of social preferences

In-hospital cardiac arrests: Effect of amended Australian Resuscitation Council 2006 guidelines

Objective: To evaluate cardiac arrest outcomes following the introduction of the Australian Resuscitation Council (ARC) 2006 amended guidelines for basic and advanced life support. Methods: A retrospective study of all consecutive cardiac arrests during a 3-year phase pre-implementation (2004–06) and a 3-year phase post-implementation (2007–09) of the ARC 2006 guidelines was conducted at a tertiary referral hospital in Brisbane, Australia. Results: Over the 6-year study phase 690 cardiac arrests were reported. Resuscitation was attempted in 248 patients pre-implementation and 271 patients post-implementation of the ARC 2006 guidelines. After adjusting for significant prognostic factors we found no significant change in return of spontaneous circulation (ROSC) (odds ratio 1.21, 95% confidence interval 0.80–1.85, P = 0.37) or survival to discharge (odds ratio 1.49, 95% confidence interval 0.94–2.37, P = 0.09) after the implementation of the ARC 2006 guidelines. Factors that remained significant in the final model for both outcomes included having an initial shockable rhythm, a shorter length of time from collapse to arrival of cardiac arrest team, location of the patient in a critical-care area, shorter length of resuscitation and a day-time arrest (0700–2259 hours). In addition the arrest being witnessed was significant for ROSC and younger age was significant for survival to discharge. Conclusions: There are multiple factors that influence clinical outcomes following an in-hospital cardiac arrest and further research to refine these significant variables will assist in the future management of cardiac arrests. What is known about this topic?: The evaluation of outcomes from in-hospital cardiac arrests focuses on immediate survival expressed as ROSC and survival to hospital discharge. These clinical outcomes have not improved substantially over the last two decades. What does this paper add?: This paper identifies the factors that are related to ROSC and survival to discharge following the implementation of the ARC 2006 guidelines, which included a refocus on providing quality cardiopulmonary resuscitation with minimal interruptions. What are the implications for practitioners?: Given that multiple factors can influence clinical outcomes following an in-hospital cardiac arrest, focusing on maximising a range of factors surrounding cardiopulmonary resuscitation is essential to improve outcomes

Impulsiveness Mediates the Association between \u3ci\u3eGABRA2\u3c/i\u3e SNPs and Lifetime Alcohol Problems

Genetic variants in GABRA2 have previously been shown to be associated with alcohol measures, electroencephalography (EEG) β waves and impulsiveness-related traits. Impulsiveness is a behavioral risk factor for alcohol and other substance abuse. Here, we tested association between 11 variants in GABRA2 with NEO-impulsiveness and problem drinking. Our sample of 295 unrelated adult subjects was from a community of families with at least one male with DSM-IV alcohol use diagnosis, and from a socioeconomically comparable control group. Ten GABRA2 SNPs (single-nucleotide polymorphisms) were associated with the NEO-impulsiveness (P \u3c 0.03). The alleles associated with higher impulsiveness correspond to the minor alleles identified in previous alcohol dependence studies. All ten SNPs are in linkage disequilibrium (LD) with each other and represent one effect on impulsiveness. Four SNPs and the corresponding haplotype from intron 3 to intron 4 were also associated with Lifetime Alcohol Problems Score (LAPS, P \u3c 0.03) (not corrected for multiple testing). Impulsiveness partially mediates (22.6% average) this relation between GABRA2 and LAPS. Our results suggest that GABRA2 variation in the region between introns 3 and 4 is associated with impulsiveness and this effect partially influences the development of alcohol problems, but a direct effect of GABRA2 on problem drinking remains. A potential functional SNP rs279827, located next to a splice site, is located in the most significant region for both impulsiveness and LAPS. The high degree of LD among nine of these SNPs and the conditional analyses we have performed suggest that all variants represent one signal

A cognitive map in a poison frog

© 2019. Published by The Company of Biologists Ltd A fundamental question in cognitive science is whether an animal can use a cognitive map. A cognitive map is a mental representation of the external world, and knowledge of one’s place in this world, that can be used to determine efficient routes to any destination. Many birds and mammals are known to employ a cognitive map, but whether other vertebrates can create a cognitive map is less clear. Amphibians are capable of using beacons, gradients and landmarks when navigating, and many are proficient at homing. Yet only one prior study directly tested for a cognitive map in amphibians, with negative results. Poison frogs exhibit unusually complex social and spatial behaviors and are capable of long-distance homing after displacement, suggesting that they may be using complex spatial navigation strategies in nature. Here, we trained the poison frog Dendrobates auratus in a modified Morris water maze that was designed to suppress thigmotaxis to the maze wall, promoting exploration of the arena. In our moat maze, the poison frogs were able to use a configuration of visual cues to find the hidden platform. Moreover, we demonstrate that they chose direct paths to the goal from multiple random initial positions, a hallmark of a cognitive map. The performance of the frogs in the maze was qualitatively similar to that of rodents, suggesting that the potential to evolve a cognitive map is an evolutionarily conserved trait of vertebrates

From theory to practice: professional experimentation in the course of graphic design

Da teoria à prática: a experimentação profissional no curso de design gráficoEste artigo relata um caso de aproximação de estudantes de design com o mercado de trabalho. Alunos do curso de graduação em design gráfico da Universidade Federal de Santa Catarina participaram de experimentação profissional na disciplina de Metodologia e Desenvolvimento de Projetos II, através do desenvolvimento de um projeto de programação visual para uma ação de reciclagem de óleo vegetal usado. A experiência foi fundamental para preparar os alunos para o mercado de trabalho, além de estimular para o bom aproveitamento da disciplina. Para a ação de reciclagem de óleo vegetal usado, os resultados alcançados mostraram-se tecnicamente adequados, superando expectativas