Axially open nonradiative structures: an example of single-mode resonator based on the sample holder

The concept of nonradiative dielectric resonator is generalized in order to include axially open configurations having rotational invariance. The resulting additional nonradiative conditions are established for the different resonance modes on the basis of their azimuthal modal index. An approximate chart of the allowed dielectric and geometrical parameters for the TE011 mode is given. A practical realization of the proposed device based on commercial fused quartz tubes is demonstrated at millimeter wavelengths, together with simple excitation and tuning mechanisms. The observed resonances are characterized in their basic parameters, as well as in the field distribution by means of a finite element method. The predictions of the theoretical analysis are well confirmed, both in the general behaviour and in the expected quality factors. The resulting device, in which the sample holder acts itself as single-mode resonating element, combines an extreme ease of realization with state-of-the-art performances. The general benefits of the proposed open single-mode resonators are finally discussed.Comment: 18 pages, 10 figure

Европа и педагогическая проблема межкультурного взаимодействия: знание и личное участие за пределами утопии

In western states today, and not only in these quarters, there are noteworthy and dangerous oscillations between extreme forms of nationalism and more democratic trends. There is a tendency to shut off towards other nations, to see one's own nationality as a cultural and traditional dimension in need of protection, currently under threat from invasion by other ethnicities, who cannot easily be assimilated to one's own values and principles. How, then, is it possible to overcome the appeal of ideologies of resistance of nationalistic, conservative type? In all probability, an excellent first step is offered by the new pedagogical rationality of education for democracy, which is at the head of the current of critical pedagogy of emancipation, calling for responsible choices and direct participation in the democratic life of a civil society

A New Contact Mat Wireless System for Estimating Vertical Jump Height

Abstract Among the different devices available for the assessment of the vertical jump height based on the flight time measurement, the contact mats are surely one of the simplest and portable systems and, for this reason, they are more widely used. This paper deals with the comparative evaluation of the performances of a new contact mat system with respect to a force platform. Some tests have been performed and the relative comparative results will be presented. The study shows a significant concurrent validity of Wi-JumpLe system for the flight and ground contact time measurements. In conclusion, the new contact mat structure together with the electronic measurement system is legitimate to assess vertical jump height and leg extensors muscle power

The Interval Kicking Program (IKP) as a Reprogramming Technique for the Soccer Player in an Anterior Cruciate Ligament (ACL) Rehabilitation: A Technical Report

Introduction. We can state as technical-athletic gestural movements that we might call clinical (pivoting, cutting maneuvers, sidestep cuts, changes of direction) associated with ACL injuries. Objective. This technical report was conducted to research methods of reprogramming basic technical skills in the soccer player after anterior cruciate ligament reconstructive surgery. Technical report results. The Interval Kicking Program (IKP) is a model proposed as a neuromotor remodelling of basic gestures and techniques after an ACL injury in soccer player. The teaching progression is ordered regarding the diversified techniques of passing and receiving the ball. The volume, intensity, and progression steps are governed by 1) clinical status (i.e., type of injury, conservative/surgical treatment type, type of sport), 2) performance status, and 3) objective evaluative analysis of periodic follow-ups. The steps provid-ed by the IKP can be 15 and end with the introduction of the player into technical drills with the presence of opponents the first sessions include about 30 minutes of sport-specific, low-intensity exercises, while in the last ones, the volume remains constant, but the intensity and technical complexity of the movements increase. Conclusions. In this technical report, we have highlighted how IKP can be a teaching model for reprogramming basic technical skills in the soccer player after injury. It remains fair to point out how aberrant technical movement partners, side-to-side asymmetries, and postur-al dysfunction are predictive of the risk of compliance and second injury. Further studies and insights are needed to customize the reprogramming of the soccer player’s gestural movements during return to play. © 2023, EDRA S.p.A. All rights reserved

The effect of age, sex and a firm-textured surface on postural control.

In previous studies, the influence of plantar sensation has been examined using various textured surfaces with different stiffness materials to assess static balance. This study investigated the effects of a Firm Textured Surface (FTS) along with age and sex-related influences on postural control under different visual conditions. Forty subjects (20 elderly, 10 males, mean age 68.30, 10 females, mean age 68.00, and 20 young people, 10 males, mean age 25.45, 10 females, mean age 27.30) participated in this study maintained a quiet standing on FTS, foam and firm surfaces with eyes open and closed. The center of pressure displacement (CoPDISP), CoP velocity (CoPVEL), and sway velocity of the CoP in anteroposterior (AP) and mediolateral (ML) direction (VA/P and VM/L) were measured. FTS was associated with lower postural sway measures in both the groups with eyes open and closed. However, the foam surface showed the worst results in all postural parameters under all experimental conditions. Separate four-way ANOVAs were applied to each dependent variable. The main effects of surface (p < 0.0001), vision (p < 0.0001) and age (p < 0.0001 for CoPDISP, CoPVEL and VA/P; p = 0.0003 for VM/L) were significant in each of the four fitted models. Sex was never significant, either as a main effect or an interaction with other experimental factors. Eyes open were able to reduce the negative effects of the foam surfaces but without vision the proprioceptive sensory system cues of the body state become more important for maintaining balance. A good stimulation with rigid texture should be considered as relief to reduce the physiological-related decline of afferent information with ag

Effect of segmental muscle vibration on upper extremity functional ability poststroke: A randomized controlled trial.

Abstract Background: Upper extremity functional impairments are common consequences of stroke. Therefore, continuous investigation of effective interventions for upper extremity functions after stroke is a necessity. Segmental muscle vibration (SMV) is one of the interventions that incorporate sensory stimulation to improve motor cortical excitability. The aim of this study was to investigate the influence of 5-minute SMV application along with supervised physical therapy (SPT) on improving activities of daily living and motor recovery on the hemiparetic upper extremity in patients with stroke. Methods: A sample of 37 patients poststroke (29 males) was randomly allocated to either SPT control group (n=18) or SPT and SMV (SPT-SMV) experimental group (n=19). All patients received 3 sessions per week of SPT for 8 weeks. The SPT-SMV experimental group received SMV at the end of each SPT session. Outcome measures used were Barthel index (BI), modified Ashworth scale, manual muscle testing, and goniometry for range of motion (ROM) assessment. Results: Thirty-four patients completed the study. Patients in both groups improved significantly after treatment in BI, elbow ROM, and elbow muscles strength. However, muscle tone in elbow joint of the hemiplegic upper extremity improved significantly after SMV only in the experimental group (SPT-SMV). Conclusion: The SPT intervention can improve functional outcomes of upper extremity in people after stroke. However, using SMV may have superior effect on improving muscle tone after stroke. Abbreviations: ADL = activities of daily living, BI = Barthel index, MAS = modified Ashworth scale, MMT = manual muscle testing, ROM = range of motion, SMV = segmental muscle vibration, SPT = supervised physical therapy, SPT-SMV = supervised physical therapy and segmental muscle vibration

Specificity of weightlifting bench exercises in kayaking sprint performance: A perspective for neuromuscular training

Several studies showed significant differences between bench lift exercises without investigating which is more related, in biomechanical and neuromuscular terms, to improve the sprint flatwater kayak performance. This study aims to compare the power-load and velocity-load neuromuscular parameters performed in prone bench pull (PBP), and bench press (BP) exercises to identify which of them meet the gesture specificity in sprint flatwater kayak performance. Ten elite kayakers participated in this study. Power-load, velocity-load relationships, the maximum dynamic strength, and the kayak sprint performance test were assessed. The power-load and velocity-load relationships showed significant differences between the PBP and BP for each considered load. The kayakers showed a significant correlation between maximum power performed on the PBP and the maximum velocity reached in the kayak sprint (r = 0.80, p < 0.01) and the stroke frequency (r = 0.61, p < 0.05). Conversely, the maximum power performed on the BP did not correlate with the kinematic parameters analyzed. In addition, the maximum dynamic strength in the PBP and BP did not correlate with the maximum velocity and stroke frequency. Furthermore, no significant difference was observed in both the bench exercises for the maximum dynamic strength (p > 0.05). The results of this study suggest that the maximal muscular power expressed in PBP exercise only seems to be more specific in kayak velocity performance compared with maximal dynamic strength and with all dynamic parameters recorded in the BP. This will allow coaches and trainers to use specific bench exercises for specific neuromuscular kayakers’ adaptations during the whole competitive season

A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy-barriers revealed by high-field Electron Spin Resonance spectroscopy

The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field Electron Spin Resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy-barriers for the rotational motion of the spin probe is unambigously evidenced at both 240K and 270K. The same shape for the distribution of the energy-barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy-barriers distribution of the spin probe is in the range of the estimates of the breadth of the PS energy-barriers distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy-barriers distribution agrees with results from extreme-value statistics and the trap model by Bouchaud and coworkers.Comment: Final version in press as Letter to the Editor on J.Phys.:Condensed Matter. Changes in bol

Open nonradiative cavities as millimeter wave single-mode resonators

Open single-mode metallic cavities operating in nonradiative configurations are proposed and demonstrated. Starting from well-known dielectric resonators, possible nonradiative cavities have been established; their behavior on the fundamental TE011 mode has been predicted on the basis of general considerations. As a result, very efficient confinement properties are expected for a wide variety of open structures having rotational invariance. Test cavities realized having in mind practical millimeter wave constraints have been characterized at microwave frequencies. The field distribution of some relevant configurations has been modeled by means of a finite-element numerical method. The obtained results confirm the expected high performances on widely open configurations. A possible excitation of the proposed resonators exploiting their nonradiative character is discussed, and the resulting overall ease of realization enlightened in view of millimeter wave employments.Comment: 18 pages, 10 figures. Extended version including numerical modelings and a theoretical appendix. Original version published on Rev. Sci. Instru