A Single-Antenna Method and Post-Processing Strategy for Radar Cross-Section Measurements at Near-Field Ranges.

The single-antenna technique proposed in this paper was developed for measuring the radar cross-section at near-field distances in a real environment, from reflection coefficient measurements on the antenna. The near-field radar cross-section is corrected with an analytical factor calculated as a ratio between the radar cross-section computed at far-field and near-field. The analytical correction factor takes into account the effects of the diffraction at the edges of the target at incidence angles higher than 20°. An improved, distance averaging technique is proposed to reduce the multipath propagation effects. A time-gating procedure is additionally used in order to better isolate the reflection from the target and to remove the real environment contributions. The method was successfully tested on a rectangular metallic plate as a target over a wide frequency band, at normal and oblique incidence angles; however, it might also work for arbitrarily shaped targets, because they can actually be divided into small rectangular patches.

Decline in Running Performance in Highest-Level Soccer: Analysis of the UEFA Champions League Matches.

It is widely recognized that there is a decline in match running performance (MRP) towards the end of matches. To clarify whether it is primarily a consequence of fatigue, pacing or situational influences, this study aimed to examine MRP across 15-min match periods for players on different playing positions. Players' MRP (n = 244) were examined from the UEFA Champions League matches (n = 20) using a semiautomatic optical tracking system. Linear mixed models for repeated measures were adjusted to analyze MRP over the six 15-min match periods while controlling the influence of situational factors. No effects of match outcome, match location, team, and opponent quality on total distance (TD) and high-intensity running (HIR) for players in all playing positions were found (F = 0.03−2.75; all p > 0.05). Significant differences in TD (F = 17.57−53.01; η2 = 0.39−0.52, all large effect sizes) and HIR (F = 3.67−7.64; η2 = 0.05−0.19, small to medium effect sizes) among six 15-minute match periods were found for players in all playing positions. In addition, players in all playing positions covered less TD (d = 1.41−2.15, large to very large effect sizes) and HIR (d = 0.16−0.6, trivial to medium effect sizes) in the last compared to the first 15-min match period. No differences in TD and HIR between the last two match periods in the second half were observed. This study confirmed that soccer players reduce MRP towards the end of matches, and suggest that the decline of MPR in highest-level soccer may be a consequence of pacing strategies.

Effectiveness of Radial Extracorporeal Shock Wave Therapy and Visual Feedback Balance Training on Lower Limb Post-Stroke Spasticity, Trunk Performance, and Balance: A Randomized Controlled Trial.

Stroke remains one of the leading causes of disability in adults, and lower limb spasticity, affected stance, and balance impact everyday life and activities of such patients. Robotic therapy and assessment are becoming important tools to clinical evaluation for post-stroke rehabilitation. The aim of this study was to determine in a more objective manner the effects of visual feedback balance training through a balance trainer system and radial extracorporeal shock wave therapy (rESWT), along with conventional physiotherapy, on lower limb post-stroke spasticity, trunk control, and static and dynamic balance through clinical and stabilometric assessment. The study was designed as a randomized controlled trial. The experimental group underwent conventional physiotherapy, visual feedback balance training, and rESWT. The control group underwent conventional physiotherapy, visual feedback training and sham rESWT. The statistical analysis was performed using GraphPad Software and MATLAB. Primary clinical outcome measures were The Modified Ashworth Scale (MAS), passive range of motion (PROM), Visual Analogue Scale (VAS), and Clonus score. Secondary outcome measures were trunk performance, sensorimotor, and lower limb function. Stabilometric outcome measures were trunk control, static balance, and dynamic balance. Visual feedback training using the Prokin system and rESWT intervention, along with conventional physiotherapy, yielded statistically significant improvement both on clinical and stabilometric outcome measures, enhancing static and dynamic balance, trunk performance, sensorimotor outcome, and limb function and considerably diminishing lower limb spasticity, pain intensity, and clonus score in the experimental group.

Long-Term Efficacy of Extracorporeal Shock Wave Therapy on Lower Limb Post-Stroke Spasticity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

The purpose of this systematic review and meta-analysis is to evaluate the long-term efficacy of Extracorporeal Shock Wave Therapy (ESWT) on reducing lower limb post-stroke spasticity in adults. A systematic electronic search of PubMed/ MEDLINE, Physiotherapy Evidence Database (PEDro), Scopus, Ovid MEDLINE(R), and search engine of Google Scholar was performed. Publications that ranged from January 2010 to August 2020, published in English, French, Spanish, Portuguese, and Italian language and available as full texts were eligible for inclusion and they were searched without any restrictions of country. The study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines and followed the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions. Two authors screened the references, extracted data, and assessed the risk of bias. The primary outcome was spasticity grade mainly assessed by the Modified Ashworth Scale (MAS). Secondary outcomes were passive range of motion (PROM), pain intensity, electrophysiological parameters, gait assessment, and adverse events. A total of seven recent randomized controlled trials (RCTs) were included in the systematic review and meta-analysis, and a beneficial effect on spasticity was found. The high level of evidence presented in this paper showed that ESWT ameliorates spasticity considering the parameters: MAS: standardized mean difference (SMD) = 0.53; 95% confidence interval (95% CI): (0.07-0.99); Modified Tardieu Scale (MTS): SMD = 0.56; 95% CI: (0.01-1.12); Visual Analogue Scale (VAS): SMD = 0.35; 95% CI: (-0.21-0.91); PROM: SMD = 0.69; 95% CI: (0.20-1.19). ESWT presented long-term efficacy on lower limb post-stroke spasticity, reduced pain intensity, and increased range of motion. The effect of this novel and non-invasive therapy was significant and the intervention did not present adverse events, proving a satisfactory safety profile.

An UWB Physical Optics Approach for Fresnel-Zone RCS Measurements on a Complex Target at Non-Normal Incidence.

In this paper, we propose a fast method for measuring the radar cross section of a complex target at non-normal incidences and Fresnel region antenna-to-target distances. The proposed method relies both on the physical optics approach and on averaging the field distribution over the transmitting and receiving antenna apertures. The ratio between the analytical expression of the radar cross section at far-field and Fresnel region results in a field-zone extrapolation factor. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that field-zone extrapolation factor. The method is suitable to be used in a perturbed, multipath environment by applying the distance averaging technique, coupling subtraction or time gating. Our technique requires a very simple measuring configuration consisting of two horn antennas and a vector network analyzer. The experimental validation of the proposed technique demonstrates reasonable agreement with simulated radar cross section at non-normal incidence.