The design of a system of adjustable superconducting plates for balancing a gradiometer

The gradiometer of a SQUID-system for measuring very small biomagnetic signals should be made as insensitive as possible to the much larger uniform background fields. The balance of a gradiometer can be improved considerably by modifying the effective area of the gradiometer loops by a system of small adjustable superconducting plates.\ud This paper is intended as an aid for designing such a balancing system. We calculated the effective area of a gradiometer loop perpendicular to a rectangular or parallel to a circular plate. The paper contains graphs showing how large the plates have to be and where they must be placed.\ud The calculations show that for accurate balancing the distance of a plate to the wire of a loop must be large and that the plates must be as small as possible

Kako budući stručnjaci u sportu, tjelovježbi i tjelesnome odgoju percipiraju tjelesni izgled pretile djece

Anti-fat bias has been previously identified amongst practising obesity health care specialists, physical education (PE) teachers and students of exercise science and PE in samples in the USA and New Zealand. The present research investigated the perceptions of the physical self of ‘fat’ versus ‘normal-weight’ children held by 167 students studying sport exercise and PE related programmes in higher education in England. Onesample t-tests identified that the sample held negative perceptions towards ‘fat’ children (identified by subscale mean scores that were significantly different from the subscale mean of 2.5 that would identify equivocal perception between ‘fat’ and ‘normal-weight’ children) on five of the six subscales of an adapted version of the Children & Youth Physical Self Perception Profile (CONDITION 1.52±.49; BODY 1.63±.43; PHYSICAL SELF-WORTH 1.79±.47; SPORT 1.88±.45; GLOBAL SELF-ESTEEM 2.10±.50, all p<.01; STRENGTH 2.48±.52, p=.67). Such results are indicative of the obesity discourse that currently prevails within PE and sport professions; a discourse constructed, arguably, on misleading foundations. Obesity awareness training is, therefore, required in such trainee exercise science, sport and PE populations. Pedagogical approaches espoused during programmes of study ought to emphasize personal meaning, personal reference and childcenteredness so that such approaches are more likely to be employed in their future professional practice.Predrasude prema pretilim ljudima utvrđene su kod specijalista zdravstvene skrbi koji se bave pretilošću, kod profesora tjelesne i zdravstvene kulture te studenata kineziologije u SAD-u i Novom Zelandu. Cilj provedenog istraživanja bio je utvrditi percepcije tjelesnog izgleda “debele” u odnosu na djecu “normalne težine” kod 167 studenata kineziologije (sporta, vježbanja i fizičke kulture) u Engleskoj. Rezultati t-testova su pokazali da su ispitanici imali negativnu percepciju pretile djece (utvrđeno srednjim vrijednostima podljestvice koje su se statistički značajno razlikovale od njezine aritmetičke sredine (2,5) koja bi potvrdila jednaku percepciju pretile djece i djece normalne težine), na pet od ukupno šest podljestvica adaptirane verzije upitnika Children & Youth Physical Self Perception Profile (kondicijska pripremljenost 1.52±.49; slika tijela 1.63±.43; tjelesno samovrednovanje 1.79±.47; sportska kompetencija 1.88±.45; opće samopouzdanje 2.10±.50, svi na razini značajnosti p<.01; te tjelesna jakost i snaga 2.48±.52, p=.67). Dobiveni rezultati su indikativni za odnos prema pretilim osobama koji trenutno prevladava kod profesionalnih djelatnika u sportu i tjelesnoj i zdravstvenoj kulturi, a koji je nedvojbeno izgrađen na pogrešnim temeljima. Stoga je za populacije pripravnika u kineziologiji, sportu i tjelesnoj i zdravstvenoj kulturi potrebna edukacija i razvoj svijesti o pretilosti. Pedagoški pristupi koji se provode u okviru studijskih programa trebali bi naglasiti osobnost pojedinca, te osobni odnos i orijentaciju prema djetetu kako bi takvi pristupi i takav odnos prema djeci bili i primijenjeni u budućem profesionalnom radu sportskih stručnjaka i znanstvenika

The twin paradox in compact spaces

Twins travelling at constant relative velocity will each see the other's time dilate leading to the apparent paradox that each twin believes the other ages more slowly. In a finite space, the twins can both be on inertial, periodic orbits so that they have the opportunity to compare their ages when their paths cross. As we show, they will agree on their respective ages and avoid the paradox. The resolution relies on the selection of a preferred frame singled out by the topology of the space.Comment: to be published in PRA, 3 page

Peripheral and central inputs shape network dynamics in the developing visual cortex in vivo

Spontaneous network activity constitutes a central theme during the development of neuronal circuitry [1, 2]. Before the onset of vision, retinal neurons generate waves of spontaneous activity that are relayed along the ascending visual pathway [3, 4] and shape activity patterns in these regions [5, 6]. The spatiotemporal nature of retinal waves is required to establish precise functional maps in higher visual areas, and their disruption results in enlarged axonal projection areas (e.g., [7-10]). However, how retinal inputs shape network dynamics in the visual cortex on the cellular level is unknown. Using in vivo two-photon calcium imaging, we identified two independently occurring patterns of network activity in the mouse primary visual cortex (V1) before and at the onset of vision. Acute manipulations of spontaneous retinal activity revealed that one type of network activity largely originated in the retina and was characterized by low synchronicity (L-) events. In addition, we identified a type of high synchronicity (H-) events that required gap junction signaling but were independent of retinal input. Moreover, the patterns differed in wave progression and developmental profile. Our data suggest that different activity patterns have complementary functions during the formation of synaptic circuits in the developing visual cortex

Age and Grip Strength Predict Hand Dexterity in Adults.

In the scientific literature, there is much evidence of a relationship between age and dexterity, where increased age is related to slower, less nimble and less smooth, less coordinated and less controlled performances. While some suggest that the relationship is a direct consequence of reduced muscle strength associated to increased age, there is a lack of research that has systematically investigated the relationships between age, strength and hand dexterity. Therefore, the aim of this study was to examine the associations between age, grip strength and dexterity. 107 adults (range 18-93 years) completed a series of hand dexterity tasks (i.e. steadiness, line tracking, aiming, and tapping) and a test of maximal grip strength. We performed three phases of analyses. Firstly, we evaluated the simple relationships between pairs of variables; replicating the existing literature; and found significant relationships of increased age and reduced strength; increased age and reduced dexterity, and; reduced strength and reduced dexterity. Secondly, we used standard Multiple Regression (MR) models to determine which of the age and strength factors accounted for the greater variance in dexterity. The results showed that both age and strength made significant contributions to the data variance, but that age explained more of the variance in steadiness and line tracking dexterity, whereas strength explained more of the variance in aiming and tapping dexterity. In a third phase of analysis, we used MR analyses to show an interaction between age and strength on steadiness hand dexterity. Simple Slopes posthoc analyses showed that the interaction was explained by the middle to older aged adults showing a relationship between reduced strength and reduced hand steadiness, whereas younger aged adults showed no relationship between strength and steadiness hand dexterity. The results are discussed in terms of how age and grip strength predict different types of hand dexterity in adults

Statistical mechanics in the context of special relativity

In the present effort we show that $S_{\kappa}=-k_B \int d^3p (n^{1+\kappa}-n^{1-\kappa})/(2\kappa)$ is the unique existing entropy obtained by a continuous deformation of the Shannon-Boltzmann entropy $S_0=-k_B \int d^3p n \ln n$ and preserving unaltered its fundamental properties of concavity, additivity and extensivity. Subsequently, we explain the origin of the deformation mechanism introduced by $\kappa$ and show that this deformation emerges naturally within the Einstein special relativity. Furthermore, we extend the theory in order to treat statistical systems in a time dependent and relativistic context. Then, we show that it is possible to determine in a self consistent scheme within the special relativity the values of the free parameter $\kappa$ which results to depend on the light speed $c$ and reduces to zero as $c \to \infty$ recovering in this way the ordinary statistical mechanics and thermodynamics. The novel statistical mechanics constructed starting from the above entropy, preserves unaltered the mathematical and epistemological structure of the ordinary statistical mechanics and is suitable to describe a very large class of experimentally observed phenomena in low and high energy physics and in natural, economic and social sciences. Finally, in order to test the correctness and predictability of the theory, as working example we consider the cosmic rays spectrum, which spans 13 decades in energy and 33 decades in flux, finding a high quality agreement between our predictions and observed data. PACS number(s): 05.20.-y, 51.10.+y, 03.30.+p, 02.20.-aComment: 17 pages (two columns), 5 figures, RevTeX4, minor typing correction

Interpersonal stance in police interviews: content analysis

A serious game for learning the social skills required for effective police interviewing is a challenging idea. Building artificial conversational characters that play the role of a suspect in a police interrogation game requires computational models of police interviews as well as of the internal psychological mechanisms that determine the behaviour of suspects in this special type of dialogues. Leary's interactional circumplex is used in police interview training as a theoretical framework to understand how suspects take stance during an interview and how this is related to the stance and the strategy that the interviewer takes. Interactional stance is a fuzzy notion. The question that we consider here is whether different observers of police nterviews agree on the type of stance that suspect and policemen take and express in a face-to-face interview. We analyzed police interviews and report about a stance annotation exercise. We conclude that although inter-annotator agreement on stance labeling on the level of speech segments is low, a majority voting meta-annotator" is able to reveal the important dynamics in stance taking in a police interview. Then we explore the relation between the stance taken by the suspect and turn-taking behaviour, overlaps, interruptions, pauses and silences. Our findings contribute to building computational models of non-player characters that allow more natural turn-taking behaviour in serious games instead of the one-at-a-time regime in interview training games