Quantum Turbulent Structure in Light

The infinite superpositions of random plane waves are known to be threaded with vortex line singularities which form complicated tangles and obey strict topological rules. We observe that within these structures a timelike axis appears to emerge with which we can define vortex velocities in a useful way: with both numerical simulations and optical experiments, we show that the statistics of these velocities match those of turbulent quantum fluids such as superfluid helium and atomic Bose-Einstein condensates. These statistics are shown to be independent of system scale. These results raise deep questions about the general nature of quantum chaos and the role of nonlinearity in the structure of turbulence.Comment: 4 pages, 2 figure

Applications of Commutator-Type Operators to pp-Groups

For a p-group G admitting an automorphism $\phi$ of order $p^n$ with exactly $p^m$ fixed points such that $\phi^{p^{n-1}}$ has exactly $p^k$ fixed points, we prove that G has a fully-invariant subgroup of m-bounded nilpotency class with $(p,n,m,k)$-bounded index in G. We also establish its analogue for Lie p-rings. The proofs make use of the theory of commutator-type operators.Comment: 11 page

Applying the contact hypothesis to anti-fat attitudes: Contact with overweight people is related to how we interact with our bodies and those of others

This paper is the first to apply the contact hypothesis, a social psychological theory of prejudice reduction, to the field of weight bias. It aims to investigate whether contact with overweight people is associated with the extent to which people report weight bias, as well as vigilance around their own bodies. In 2013 we recruited 1176 American participants to complete surveys regarding prejudice toward overweight people, as well as a suite of measures capturing people's relationships with their own weight (fat talk, drive for thinness, and body-checking behavior). Positive contact with overweight people predicted decreased prejudice, regardless of whether participants were overweight (p < .001) or not (p 젮003). However, negative contact was a stronger predictor of increased prejudice (p < .001 for both samples). For non-overweight participants, any contact with overweight people (whether positive or negative) predicted increased body-checking behaviors (positive-p 젮002, negative-p < .001) and fat talk (positive-p 젮047, negative-p < .001), and negative contact predicted increased drive for thinness (p < .001). However, for those who were overweight a different picture emerged. While negative contact predicted increased body-checking behaviors (p < .001) and fat talk (p < .001), positive contact was protective, predicting decreased drive for thinness (p 젮001) and body-checking behaviors (p < .001). This paper demonstrates that the interactions we have with overweight people are inherently tied to both our attitudes towards them and our relationship with our own bodies.Full Tex

The Dissociation between Early and Late Selection in Older Adults

Older adults exhibit a reduced ability to ignore task-irrelevant stimuli; however, it remains to be determined where along the information processing stream the most salient age-associated changes occur. In the current study, ERPs provided an opportunity to determine whether age-related differences in processing task-irrelevant stimuli were uniform across information processing stages or disproportionately affected either early or late selection. ERPs were measured in young and old adults during a color-selective attention task in which participants responded to target letters in a specified color (attend condition) while ignoring letters in a different color (ignore condition). Old participants were matched to two groups of young participants on the basis of neuropsychological test performance: one using age-appropriate norms and the other using test scores not adjusted for age. There were no age-associated differences in the magnitude of early selection (attend–ignore), as indexed by the size of the anterior selection positivity and posterior selection negativity. During late selection, as indexed by P3b amplitude, both groups of young participants generated neural responses to target letters under the attend versus ignore conditions that were highly differentiated. In striking contrast, old participants generated a P3b to target letters with no reliable differences between conditions. Individuals who were slow to initiate early selection appeared to be less successful at executing late selection. Despite relative preservation of the operations of early selection, processing delays may lead older participants to allocate excessive resources to task-irrelevant stimuli during late selection

Программное обеспечение для обучения в малых группах

This article focuses on the method of group training which represents one of the most actual and perspective forms of the organization of educational process. Authors confirm the theoretical conclusions with the experiment made with students of specialty "Information Systems and Technologies". Besides, article includes the description opportunities of the program adapted for work in small groups.В данной статье рассматривается метод группового обучения, который представляет собой одну из наиболее актуальных и перспективных форм организации учебного процесса. Авторы подтверждают свои теоретические выводы экспериментом, проведенным со студентами старших курсов специальности «Информационные системы и технологии». Кроме того, статья включает описание возможностей программы, адаптированной для выполнения общего задания в группах

Implementation of the Projector Augmented Wave LDA+U Method: Application to the Electronic Structure of NiO

The so-called local density approximation plus the multi-orbital mean-field Hubbard model (LDA+U) has been implemented within the all-electron projector augmented-wave method (PAW), and then used to compute the insulating antiferromagnetic ground state of NiO and its optical properties. The electronic and optical properties have been investigated as a function of the Coulomb repulsion parameter U. We find that the value obtained from constrained LDA (U=8 eV) is not the best possible choice, whereas an intermediate value (U=5 eV) reproduces the experimental magnetic moment and optical properties satisfactorily. At intermediate U, the nature of the band gap is a mixture of charge transfer and Mott-Hubbard type, and becomes almost purely of the charge-transfer type at higher values of U. This is due to the enhancement of the oxygen 2p states near the top of the valence states with increasing U value.Comment: 23 pages, 6 figures, submitted to Phys. Rev.

Total positivity: tests and parametrizations

An introduction to total positivity (TP), with the emphasis on efficient TP criteria and parametrizations of TP matrices. Intended for general mathematical audience.Comment: 20 pages, with color figure

Property (T) and rigidity for actions on Banach spaces

We study property (T) and the fixed point property for actions on $L^p$ and other Banach spaces. We show that property (T) holds when $L^2$ is replaced by $L^p$ (and even a subspace/quotient of $L^p$), and that in fact it is independent of $1\leq p<\infty$. We show that the fixed point property for $L^p$ follows from property (T) when 1. For simple Lie groups and their lattices, we prove that the fixed point property for $L^p$ holds for any $1< p<\infty$ if and only if the rank is at least two. Finally, we obtain a superrigidity result for actions of irreducible lattices in products of general groups on superreflexive Banach spaces.Comment: Many minor improvement