Two applications of the subnormality of the Hessenberg matrix related to general orthogonal polynomials

In this paper we prove two consequences of the subnormal character of the Hessenberg matrix D when the hermitian matrix M of an inner product is a moment matrix. If this inner product is defined by a measure supported on an algebraic curve in the complex plane, then D satisfies the equation of the curve in a noncommutative sense. We also prove an extension of the Krein theorem for discrete measures on the complex plane based on properties of subnormal operators

Deceptive body movements reverse spatial cueing in soccer

This article has been made available through the Brunel Open Access Publishing Fund.The purpose of the experiments was to analyse the spatial cueing effects of the movements of soccer players executing normal and deceptive (step-over) turns with the ball. Stimuli comprised normal resolution or point-light video clips of soccer players dribbling a football towards the observer then turning right or left with the ball. Clips were curtailed before or on the turn (-160, -80, 0 or +80 ms) to examine the time course of direction prediction and spatial cueing effects. Participants were divided into higher-skilled (HS) and lower-skilled (LS) groups according to soccer experience. In experiment 1, accuracy on full video clips was higher than on point-light but results followed the same overall pattern. Both HS and LS groups correctly identified direction on normal moves at all occlusion levels. For deceptive moves, LS participants were significantly worse than chance and HS participants were somewhat more accurate but nevertheless substantially impaired. In experiment 2, point-light clips were used to cue a lateral target. HS and LS groups showed faster reaction times to targets that were congruent with the direction of normal turns, and to targets incongruent with the direction of deceptive turns. The reversed cueing by deceptive moves coincided with earlier kinematic events than cueing by normal moves. It is concluded that the body kinematics of soccer players generate spatial cueing effects when viewed from an opponent's perspective. This could create a reaction time advantage when anticipating the direction of a normal move. A deceptive move is designed to turn this cueing advantage into a disadvantage. Acting on the basis of advance information, the presence of deceptive moves primes responses in the wrong direction, which may be only partly mitigated by delaying a response until veridical cues emerge

Metabolic Syndrome features and risk of neural tube defects

Research articl

Do experts see it in slow motion? Altered timing of action simulation uncovers domain-specific perceptual processing in expert athletes

Accurate encoding of the spatio-temporal properties of others' actions is essential for the successful implementation of daily activities and, even more, for successful sportive performance, given its role in movement coordination and action anticipation. Here we investigated whether athletes are provided with special perceptual processing of spatio-temporal properties of familiar sportive actions. Basketball and volleyball players and novices were presented with short video-clips of free basketball throws that were partially occluded ahead of realization and were asked to judge whether a subsequently presented pose was either taken from the same throw depicted in the occluded video (action identification task) or temporally congruent with the expected course of the action during the occlusion period (explicit timing task). Results showed that basketball players outperformed the other groups in detecting action compatibility when the pose depicted earlier or synchronous, but not later phases of the movement as compared to the natural course of the action during occlusion. No difference was obtained for explicit estimations of timing compatibility. This leads us to argue that the timing of simulated actions in the experts might be slower than that of perceived actions ("slow-motion" bias), allowing for more detailed representation of ongoing actions and refined prediction abilities

Effetti dell’interazione terreno-struttura sulla risposta sismica in campo elastico e inelastico di strutture in calcestruzzo armato

Nella comune prassi progettuale gli edifici sono incastrati alla base e il moto sismico è applicato in condizioni di “campo libero”, trascurando la struttura di fondazione. Tale assunzione, plausibile per sottosuoli rigidi, può essere non realistica per terreni deformabili. Le norme americane FEMA 450 suggeriscono di considerare gli effetti di interazione terreno-struttura con approcci semplificati che possono modificare i parametri intrinseci della risposta dinamica strutturale (periodi propri di vibrare) e quelli connessi alla domanda sismica (smorzamento). I risultati di tali approcci sono stati confrontati con quelli di analisi dinamiche lineari condotte su alcuni casi studio relativi ad edifici con molle elastiche alla base al variare (1) del rapporto tra altezza dell’edificio e dimensioni della fondazione, (2) della rigidezza relativa terreno-struttura, (3) della regolarità strutturale e (4) del livello di fessurazione della struttura. Le formule semplificate forniscono stime dell’incremento dei primi due periodi di vibrazione in accordo con quelle ottenibili attraverso una modellazione degli effetti di interazione terreno-struttura mediante vincoli elastici, ad eccezione del caso di edifici fortemente irregolari in pianta. La fessurazione degli elementi strutturali tende a ridurre gli effetti di interazione. Analisi non lineari, condotte secondo i metodi CSM ed N2, hanno infine permesso di valutare l’influenza dell’interazione terreno-struttura sui rapporti Capacità/Domanda