Thermally activated interface motion in a disordered ferromagnet

We investigate interface motion in disordered ferromagnets by means of Monte Carlo simulations. For small temperatures and driving fields a so-called creep regime is found and the interface velocity obeys an Arrhenius law. We analyze the corresponding energy barrier as well as the field and temperature dependence of the prefactor.Comment: accepted for publication in Computer Physics Communication

On the false discovery rate and an asymptotically optimal rejection curve

In this paper we introduce and investigate a new rejection curve for asymptotic control of the false discovery rate (FDR) in multiple hypotheses testing problems. We first give a heuristic motivation for this new curve and propose some procedures related to it. Then we introduce a set of possible assumptions and give a unifying short proof of FDR control for procedures based on Simes' critical values, whereby certain types of dependency are allowed. This methodology of proof is then applied to other fixed rejection curves including the proposed new curve. Among others, we investigate the problem of finding least favorable parameter configurations such that the FDR becomes largest. We then derive a series of results concerning asymptotic FDR control for procedures based on the new curve and discuss several example procedures in more detail. A main result will be an asymptotic optimality statement for various procedures based on the new curve in the class of fixed rejection curves. Finally, we briefly discuss strict FDR control for a finite number of hypotheses.Comment: Published in at http://dx.doi.org/10.1214/07-AOS569 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Dependency and false discovery rate: Asymptotics

Some effort has been undertaken over the last decade to provide conditions for the control of the false discovery rate by the linear step-up procedure (LSU) for testing $n$ hypotheses when test statistics are dependent. In this paper we investigate the expected error rate (EER) and the false discovery rate (FDR) in some extreme parameter configurations when $n$ tends to infinity for test statistics being exchangeable under null hypotheses. All results are derived in terms of $p$-values. In a general setup we present a series of results concerning the interrelation of Simes' rejection curve and the (limiting) empirical distribution function of the $p$-values. Main objects under investigation are largest (limiting) crossing points between these functions, which play a key role in deriving explicit formulas for EER and FDR. As specific examples we investigate equi-correlated normal and $t$-variables in more detail and compute the limiting EER and FDR theoretically and numerically. A surprising limit behavior occurs if these models tend to independence.Comment: Published in at http://dx.doi.org/10.1214/009053607000000046 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Dynamic effect of overhangs and islands at the depinning transition in two-dimensional magnets

With the Monte Carlo methods, we systematically investigate the short-time dynamics of domain-wall motion in the two-dimensional random-field Ising model with a driving field ?DRFIM?. We accurately determine the depinning transition field and critical exponents. Through two different definitions of the domain interface, we examine the dynamics of overhangs and islands. At the depinning transition, the dynamic effect of overhangs and islands reaches maximum. We argue that this should be an important mechanism leading the DRFIM model to a different universality class from the Edwards-Wilkinson equation with quenched disorderComment: 9 pages, 6 figure

Interface Motion in Disordered Ferromagnets

We consider numerically the depinning transition in the random-field Ising model. Our analysis reveals that the three and four dimensional model displays a simple scaling behavior whereas the five dimensional scaling behavior is affected by logarithmic corrections. This suggests that d=5 is the upper critical dimension of the depinning transition in the random-field Ising model. Furthermore, we investigate the so-called creep regime (small driving fields and temperatures) where the interface velocity is given by an Arrhenius law.Comment: some misprints correcte

Responses to adversity in childhood: The effect of sex on attachment style and personality disorder traits

The current study had 3 objectives; 1) examine the indirect effects of childhood adversity on personality disorder traits through attachment style, 2) examine the effect of biological sex on the relationship between adversity and attachment, and adversity and personality disorder traits and, 3) examine how personality disorder traits can be represented within a model of basic personality. For the first objective, I tested a structural equation model (SEM) examining the indirect effects of adversity (i.e., abuse and neglect) through attachment style (anxious and avoidant) to antisocial, borderline, and psychopathic traits (lifestyle and behavioural aspects). Specifically, the regression analyses found attachment to be a mediator in the relationships between adversity and borderline traits and Factor 1 psychopathic traits, yet the SEM model did not. Because biological sex may affect the relationship between adversity and attachment (Belsky et al., 1991; Del Giudice, 2009; Del Giudice & Belsky, 2010) and antisocial (Gawda & Czubak, 2017), borderline (Gawda & Czubak, 2017), and psychopathic personality outcomes (Cale & Lillienfeld, 2002), I examined sex as a potential moderator (Objective 2). No sex differences emerged in the relations between adversity and the other variables in the model. Finally, I explored antisocial, borderline, and psychopathic personality outcomes using the HEXACO model of personality (Objective 3; Ashton & Lee, 2009). Consistent with previous research (Book, Visser, & Volk, 2015; Book et al., 2016), I found that psychopathic traits were negatively related to Honesty-Humility, Emotionality, Agreeableness, and Conscientiousness. Antisocial behaviours were predicted by low Honesty-Humility, Agreeableness, and Conscientiousness in the current study. Borderline traits were found to be related negatively to Extraversion and Conscientiousness but had a significantly positive relationship with Emotionality. Limitations, future research, and implications are discussed

On a Matrix Representation Lemma Useful in Determining Maximal Invariance Groups

AbstractBanken (1986, J. Multivariate Anal.19, 156–161) proposed a useful method for determining the group of all affine transformations leaving a multivariate normal testing problem invariant. His main result concerning the derivation of the maximal invariance group is heavily based on a matrix representation lemma which can be considered interesting in its own right. Unfortunately, the proof of this lemma is erroneous and there seems to be no trivial way to correct it. The aim of this note is to show the validity of the assertion

Quantification of 3D spatial correlations between state variables and distances to the grain boundary network in full-field crystal plasticity spectral method simulations

Deformation microstructure heterogeneities play a pivotal role during dislocation patterning and interface network restructuring. Thus, they affect indirectly how an alloy recrystallizes if at all. Given this relevance, it has become common practice to study the evolution of deformation microstructure heterogeneities with 3D experiments and full-field crystal plasticity computer simulations including tools such as the spectral method. Quantifying material point to grain or phase boundary distances, though, is a practical challenge with spectral method crystal plasticity models because these discretize the material volume rather than mesh explicitly the grain and phase boundary interface network. This limitation calls for the development of interface reconstruction algorithms which enable us to develop specific data post-processing protocols to quantify spatial correlations between state variable values at each material point and the points' corresponding distance to the closest grain or phase boundary. This work contributes to advance such post-processing routines. Specifically, two grain reconstruction and three distancing methods are developed to solve above challenge. The individual strengths and limitations of these methods surplus the efficiency of their parallel implementation is assessed with an exemplary DAMASK large scale crystal plasticity study. We apply the new tool to assess the evolution of subtle stress and disorientation gradients towards grain boundaries.Comment: Manuscript submitted to Modelling and Simulation in Materials Science and Engineerin