Postural evaluation in young skaters: effect of two proprioceptive training

The roller skating involves developing of motor and artistic skills from an early age. The aim was to evaluate the effects that an ocular a podalic proprioceptive training cause to postural control and stability in a sample of young skaters. A total of 25 skaters aged between 9 and 15 (12±2.14) divided into two groups: the eyes group (EG) aimed at exercising visual proprioception, the feet group (FG) aimed at exercising podalic proprioception. The participants were subject to through electronic stabilometry in static mode, open (OE) and closed (CE) eyes, in a time T0 (pre-training) and T1 (post-training), without and with skates. The results through the two paired t-test showed that both variables Wz (TotHz) to CE within the EG (p<.05) and Wx (TotHz) to CE within the FG (p<.05) were statistical significance. The unpaired t-test showed that the FG obtained a greater statistical significance than the EG for the VarVit and Wx (TotHz) variables in CE (p<.05) and Wz (TotHz) in both CE and OE (p<.05). The two-way ANOVA found statistical significance (p<.05) on the Wx (TotHz) variable in open/closed eyes of the FG (T0/T1). We concluded that in roller skating it could be useful to integrate athletic training with a visual proprioceptive training.

Peer victimization in Primary School. Gender difference

Purpose: The peer victimization is frequent phenomenon in the school. The aim of study was to investigate the gender distinction in the peer victimization, also considering the role that physical activity inside and outside school could have in this phenomenon. Methods: The study included 277 students (142 females; 134 males), between the ages of 8 and 10, attending the primary school. A questionnaire based on "Multi-dimensional Peer-Victimization Scale (MPVS)'' (Mynard et al., 2000), Italian version (Scarpa et al, 2010) and adapted to the age of the subjects, was given, to evaluate four areas of victimization (physical victimization, verbal victimization, social manipulation and attack on property). In addition, subjects were asked which physical activities they practiced in and out of school. Results: The results showed that the phenomenon victimization is present in a content way, and that males are more involved than females. Physical victimization falls more in the male gender (average value of 2±1.4 and 1.6±0.9 for the males and females, respectively), while the social manipulation in the women gender (average value of 1.9±1.2 and 1.7±1.1 for the females and males, respectively). The correlation between two or more macro-areas is there for the 74.32% of the cases and verbal victimization is the most widespread phenomenon in our sample (9.46%). The extra-school physical activity is performed by the majority of students (83.57%). Conclusions: The results confirm existing studies in the literature. The peer victimization includes not only being the obvious target of physical attacks but also includes more subtle forms of abuse, falling more in females behavior than in males

Microcavity polariton-like dispersion doublet in resonant Bragg gratings

Periodic structures resonantly coupled to excitonic media allow the existence of extra intragap modes ('Braggoritons'), due to the coupling between Bragg photon modes and 3D bulk excitons. This induces unique and unexplored dispersive features, which can be tailored by properly designing the photonic bandgap around the exciton resonance. We report that one-dimensional Braggoritons realized with semiconductor gratings have the ability to mimic the dispersion of quantum-well microcavity polaritons. This will allow the observation of new nonlinear phenomena, such as slow-light-enhanced nonlinear propagation and an efficient parametric scattering at two 'magic frequencies'

EDUCAZIONE MOTORIA E MIGLIORAMENTO DELLA DISPONIBILITÀ ATTENTIVA IN ETÀ EVOLUTIVA

L’Obbiettivo del presente lavoro è di verificare l’ipotesi secondo la quale una seduta psicomotoria condotta prima di un compito didattico (nel caso lo svolgimento di un dettato), possa incrementare la disponibilità attentiva in alunni di età compresa tra i 7 e gli 8 anni e la qualità del risultato al compito stesso. A tal fine sono stati coinvolti 170 alunni, ai quali si sono somministrati due diversi tipi di intervento: una prova di dettato (D) e una prova di dettato preceduta da una seduta di ginnastica (Ex+D). Successivamente, si è proceduto al calcolo degli errori compiuti nelle diverse prove e alle verifiche statistiche. Dall’analisi dei dati è emerso che la MEDIA degli errori compiuti nei dettati è inferiore e statisticamente significativa (p<0.0005) quando questi sono preceduti da una seduta di ginnastica psicomotoria rispetto a quando effettuati senza alcun intervento. In conclusione si è osservato che la pratica psicomotoria è da considerarsi, a tutti gli effetti, una buona opportunità per stimolare la disponibilità attentiva e migliorare le prestazioni didattiche e ciò ci fa pronunciare, senza indugio, l’esortazione affinché essa possa divenire prassi consueta in ambiente scolastico

Ionization-induced asymmetric self-phase modulation and universal modulational instability in gas-filled hollow-core photonic crystal fibers

We study theoretically the propagation of relatively long pulses with ionizing intensities in a hollow-core photonic crystal fiber filled with a Raman-inactive gas. Due to photoionization, previously unknown types of asymmetric self-phase modulation and `universal' modulational instabilities existing in both normal and anomalous dispersion regions appear. We also show that it is possible to spontaneously generate a plasma-induced continuum of blueshifting solitons, opening up new possibilities for pushing supercontinuum generation towards shorter and shorter wavelengths.Comment: 5 pages, 4 figure

Multiple hydrodynamical shocks induced by Raman effect in photonic crystal fibres

We theoretically predict the occurrence of multiple hydrodynamical-like shock phenomena in the propagation of ultrashort intense pulses in a suitably engineered photonic crystal fiber. The shocks are due to the Raman effect, which acts as a nonlocal term favoring their generation in the focusing regime. It is shown that the problem is mapped to shock formation in the presence of a slope and a gravity-like potential. The signature of multiple shocks in XFROG signals is unveiled

Dynamics of optomechanical spatial solitons in dual-nanoweb structures

We theoretically investigate the stability and dynamics of self-channelled beams that form via nonlocal optomechanical interactions in dual-nanoweb microstructured fibers. These "optomechanicons" represent a novel class of spatial soliton

Dynamics of light propagation in spatiotemporal dielectric structures

Propagation, transmission and reflection properties of linearly polarized plane waves and arbitrarily short electromagnetic pulses in one-dimensional dispersionless dielectric media possessing an arbitrary space-time dependence of the refractive index are studied by using a two-component, highly symmetric version of Maxwell's equations. The use of any slow varying amplitude approximation is avoided. Transfer matrices of sharp nonstationary interfaces are calculated explicitly, together with the amplitudes of all secondary waves produced in the scattering. Time-varying multilayer structures and spatiotemporal lenses in various configurations are investigated analytically and numerically in a unified approach. Several new effects are reported, such as pulse compression, broadening and spectral manipulation of pulses by a spatiotemporal lens, and the closure of the forbidden frequency gaps with the subsequent opening of wavenumber bandgaps in a generalized Bragg reflector

Modulational instability and solitons in excitonic semiconductor waveguides

Nonlinear light propagation in a single-mode micron-size waveguide made of semiconducting excitonic material has been theoretically studied in terms of exciton-polaritons by using an analysis based on macroscopic fields. When a light pulse is spectrally centered in the vicinity of the ground-state Wannier exciton resonance, it interacts with the medium nonlinearly. This optical cubic nonlinearity is caused by the repulsive exciton-exciton interactions in the semiconductor, and at resonance it is orders of magnitude larger than the Kerr nonlinearity (e.g., in silica). We demonstrate that a very strong and unconventional modulational instability takes place, which has not been previously reported. After reducing the problem to a single nonlinear Schr\"odinger-like equation, we also explore the formation of solitary waves both inside and outside the polaritonic gap and find evidence of spectral broadening. A realistic physical model of the excitonic waveguide structure is proposed.Comment: 7 pages (2-column), 7 figure