Emergence of acoustic and optical bands in elastic systems.

Two elastic systems are considered in this work: A special linear chain of harmonic oscillators and a quasi one-dimensional vibrating rod. Starting in both cases with a locally periodic system formed by unit cells with a single element, these cells are converted into binary cells. The acoustic and optical bands then appear. For the vibrating rod experimental values are compared with theoretical results; in particular, the normal-mode amplitudes are obtained and the agreement is excellent.

Deviations from Poisson statistics in the spectra of free rectangular thin plates.

The counterintuitive fact that wave chaos appears in the bending spectrum of free rectangular thin plates is presented. After extensive numerical simulations, varying the ratio between the length of its sides, it is shown that (i) frequency levels belonging to different symmetry classes cross each other and (ii) for levels within the same symmetry sector, only avoided crossings appear. The consequence of anticrossings is studied by calculating the distribution of the ratio of consecutive level spacings for each symmetry class. The resulting ratio distributions disagree with the expected Poissonian result. They are then compared with some well-known transition distributions between Poisson and the Gaussian orthogonal random matrix ensemble. It is found that the distribution of the ratio of consecutive level spacings agrees with the prediction of the Rosenzweig-Porter model. Also, the normal-mode vibration amplitudes are found experimentally on aluminum plates, before and after an avoided crossing for symmetrical-symmetrical, symmetrical-antisymmetrical, and antisymmetrical-symmetrical classes. The measured modes show an excellent agreement with our numerical predictions. The expected Poissonian distribution is recovered for the simply supported rectangular plate.

Emulating tightly bound electrons in crystalline solids using mechanical waves.

Solid state physics deals with systems composed of atoms with strongly bound electrons. The tunneling probability of each electron is determined by interactions that typically extend to neighboring sites, as their corresponding wave amplitudes decay rapidly away from an isolated atomic core. This kind of description is essential in condensed-matter physics, and it rules the electronic transport properties of metals, insulators and many other solid-state systems. The corresponding phenomenology is well captured by tight-binding models, where the electronic band structure emerges from atomic orbitals of isolated atoms plus their coupling to neighboring sites in a crystal. In this work, a mechanical system that emulates dynamically a quantum tightly bound electron is built. This is done by connecting mechanical resonators via locally periodic aluminum bars acting as couplers. When the frequency of a particular resonator lies within the frequency gap of a coupler, the vibrational wave amplitude imitates a bound electron orbital. The localization of the wave at the resonator site and its exponential decay along the coupler are experimentally verified. The quantum dynamical tight-binding model and frequency measurements in mechanical structures show an excellent agreement. Some applications in atomic and condensed matter physics are suggested.

Experimental Evidence of Rainbow Trapping and Bloch Oscillations of Torsional Waves in Chirped Metallic Beams.

The Bloch oscillations (BO) and the rainbow trapping (RT) are two apparently unrelated phenomena, the former arising in solid state physics and the latter in metamaterials. A Bloch oscillation, on the one hand, is a counter-intuitive effect in which electrons start to oscillate in a crystalline structure when a static electric field is applied. This effect has been observed not only in solid state physics but also in optical and acoustical structured systems since a static electric field can be mimicked by a chirped structure. The RT, on the other hand, is a phenomenon in which the speed of a wave packet is slowed down in a dielectric structure; different colors then arrive to different depths within the structure thus separating the colors also in time. Here we show experimentally the emergence of both phenomena studying the propagation of torsional waves in chirped metallic beams. Experiments are performed in three aluminum beams in which different structures were machined: one periodic and two chirped. For the smaller value of the chirping parameter the wave packets, with different central frequencies, are back-scattered at different positions inside the corrugated beam; the packets with higher central frequencies being the ones with larger penetration depths. This behavior represents the mechanical analogue of the rainbow trapping effect. This phenomenon is the precursor of the mechanical Bloch oscillations, which are here demonstrated for a larger value of the chirping parameter. It is observed that the oscillatory behavior observed at small values of the chirp parameter is rectified according to the penetration length of the wave packet.

Absorption strength in absorbing chaotic cavities.

We derive an exact formula to calculate the absorption strength in absorbing chaotic systems such as microwave cavities or acoustic resonators. The formula allows us to estimate the absorption strength as a function of the averaged reflection coefficient and the real coupling parameter. We also define the weak and strong absorption regimes in terms of the coupling parameter and the absorption strength.

Experimental evidence of coherent transport.

Coherent transport phenomena are difficult to observe due to several sources of decoherence. For instance, in the electronic transport through quantum devices the thermal smearing and dephasing, the latter induced by inelastic scattering by phonons or impurities, destroy phase coherence. In other wave systems, the temperature and dephasing may not destroy the coherence and can then be used to observe the underlying wave behaviour of the coherent phenomena. Here, we observe coherent transmission of mechanical waves through a two-dimensional elastic Sinai billiard with two waveguides. The flexural-wave transmission, performed by non-contact means, shows the quantization when a new mode becomes open. These measurements agree with the theoretical predictions of the simplest model highlighting the universal character of the transmission fluctuations.

Randomized controlled trial comparing the effectiveness of the ultrasound-guided galvanic electrolysis technique (USGET) versus conventional electro-physiotherapeutic treatment on patellar tendinopathy.

BACKGROUND: Patellar tendinopathy has a high prevalence rate among athletes. Different therapeutic options can be found in the current literature, but none of them has been clearly established as the gold standard. The purpose of this study is to compare, in a randomized controlled trial, the clinical efficacy of eccentric exercise combined with either an ultrasound-guided galvanic electrolysis technique (USGET) or conventional electrophysiotherapy to treat patellar tendinopathy. METHODS: Sixty patients diagnosed with patellar tendinopathy were randomized into two groups. Group 1 (n = 30) received electrophysiotherapy treatment consisting of ultrasound, laser and interferential current techniques. Group 2 (n = 30) received USGET. Both groups did the same standardized eccentric exercise program. Periodic assessments of the subjects were carried out with the Victorian Institute of Sport Assessment-Patella (VISA-P) score. An analysis of means and a survival study were performed. RESULTS: There were statistically significant differences in the VISA-P between the baseline and final follow-up in each treatment group. Group 1 (conventional electrophysiotherapy) went from 52.5 ± 18.8 to 61.9 ± 13.7 (in VISA-P < 90 subgroup) and from 69.1 ± 9.1 to 95.2 ± 2.5 (in VISA-P > 90 subgroup). Group 2 (USGET) went from 51.4 ± 17.9 to 63.3 ± 14.3 (in VISA-P < 90 subgroup) and from 66.3 ± 13.1 to 97.1 ± 1.7 (in VISA-P > 90 subgroup). There were statistically significant correlations between the baseline and final score in the VISA-P > 90 subjects upon completing the study but no statistically significant correlations between subjects with VISA-P < 90. The mean number of sessions applied was 22.6 ± 2.5 in Group 1 and 3.2 ± 0.9 in Group 2. The success probability in Group 1 was 36.1% versus 72.4% in Group 2. The difference was statistically significant. CONCLUSION: The results obtained with the combination of USGET and eccentric exercise reported better outcomes than with the conventional electrophysiotherapy techniques in the treatment of patellar tendinopathy.

Wave systems with direct processes and localized losses or gains: the nonunitary Poisson kernel.

We study the scattering of waves in systems with losses or gains simulated by imaginary potentials. This is done for a complex delta potential that corresponds to a spatially localized absorption or amplification. In the Argand plane the scattering matrix moves on a circle C centered on the real axis, but not at the origin, that is tangent to the unit circle. From the numerical simulations it is concluded that the distribution of the scattering matrix, when measured from the center of the circle C, agrees with the nonunitary Poisson kernel. This result is also obtained analytically by extending the analyticity condition, of unitary scattering matrices, to the no-unitary ones. We use this nonunitary Poisson kernel to obtain the distribution of nonunitary scattering matrices when measured from the origin of the Argand plane. The obtained marginal distributions have excellent agreement with the numerical results.

Wannier-stark ladders in one-dimensional elastic systems.

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this Letter we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum-mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and vice versa.

Direct processes in chaotic microwave cavities in the presence of absorption.

We quantify the presence of direct processes in the S matrix of chaotic microwave cavities with absorption in the one-channel case. To this end the full distribution P(S)(S) of the S matrix, i.e., S=sqrt[R]e(itheta), is studied in cavities with time-reversal symmetry for different antenna coupling strengths T(a) or direct processes. The experimental results are compared with random-matrix calculations and with numerical simulations including absorption. The theoretical result is a generalization of the Poisson kernel. The experimental and the numerical distributions are in excellent agreement with theoretical predictions for all cases.

Locally periodic Timoshenko rod: experiment and theory.

The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenko's beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges.

Distribution of reflection coefficients in absorbing chaotic microwave cavities.

The distribution of reflection coefficients P(R) for chaotic microwave cavities with time-reversal symmetry is investigated in different absorption and antenna coupling regimes. For all regimes the agreement between experimental distributions and random-matrix theory predictions is very good, provided both the antenna coupling T(a) and the wall absorption strength T(w) are taken into account in an appropriate way. These parameters are determined by independent experimental quantities.

Fluctuation-dissipation theorem for metastable systems.

We show that an appropriately defined fluctuation-dissipation theorem, connecting generalized susceptibilities and time correlation functions, is valid for times shorter than the nucleation time of the metastable state of Markovian systems satisfying detailed balance. This is done by assuming that such systems can be described by a superposition of the ground and first excited states of the master equation. We corroborate our results numerically for the metastable states of a two-dimensional Ising model.

Compressional and torsional wave amplitudes in rods with periodic structures.

To measure and detect elastic waves in metallic rods a low-frequency electromagnetic-acoustic transducer has been developed. Frequencies range from a few hertz up to hundreds of kilohertz. With appropriate configuration of the transducer, compressional or torsional waves can be selectively excited or detected. Although the transducer can be used in many different situations, it has been tested and applied to a locally periodic rod, which consists of a finite number of unit cells. The measured wave amplitudes are compared with theoretical ones, obtained with the one-dimensional transfer matrix method, and excellent agreement is obtained.

Incidencia de caídas en mujeres que participan periódicamente en un programa de revitalización geriátrica. Estudio con seguimiento de 5 años / Incidence of falls in women who regularly participate in a geriatric revitalitation program. A 5-year follow-up study

Introducción Las caídas constituyen uno de los síndromes más importantes en geriatría. El objetivo es conocer la incidencia de caídas durante 5 años en una población de mujeres que participan anualmente en un programa de revitalización geriátrica. Material y métodos Estudio de cohortes con seguimiento de 5 años de 137 mujeres con edades comprendidas entre los 60 y los 90 años (media ± DT: 71,65 ± 5,58 años), que participaron periódicamente en un programa de revitalización geriátrica desarrollado durante 9 meses al año. Se registran en cada periodo el número de caídas, la talla, el peso y la asistencia al programa. Se calcularon la incidencia y la tasa de caídas durante el seguimiento y el riesgo de volverse a caer. Se estudió la relación entre la edad y la asistencia al programa. Resultados Se registraron 207 caídas en 84 mujeres distintas. Incidencia de caídas a los 5 años: de 1,51 caídas/mujer. El 40% no se cayó ninguna vez en todo el periodo. El porcentaje anual de mujeres que se cayeron alguna vez varió entre el 21,2 y el 26,3%, y el de las que se cayeron 2 o más veces, entre el 0,7 y el 5%. Se registró una reducción en la tasa de caídas durante los periodos de actividad. La asistencia media osciló entre el 75 y el 83%. No se encontró relación significativa entre la asistencia ni la edad y el hecho de caerse. Conclusiones La incidencia de caídas en la población de estudio es inferior a la reportada en la literatura para el mismo segmento de la población. Los estudios que incluyen revitalización geriátrica como posible herramienta en la prevención de la discapacidad y el mantenimiento de la calidad de vida en las personas mayores son necesarios(AU)

Introduction Falls are one of the most important syndromes in geriatrics. This study has aimed to determine the incidence of falls in a 5-year period in a population of women who participate in a Geriatric Revitalization Program that is held annually. Material and methods A cohort study with a 5-year follow-up of 137 women aged 60 to 90 (mean age of 71.65 years SD 5.58) who regularly participated in a Geriatric Revitalization Program carried out 9 months a year was performed. The number of falls in each period, height, weight and the attendance to the program were recorded. Incidence and rate of falls during follow-up were calculated. The relation between age and attendance to the program were also studied. Results A total of 207 falls in 84 different women were recorded. Incidence of falls at 5 years follow-up was of 1.51 falls/women (SD 1.83). Forty percent of women did not fall during the period studied. Annual percentage of women who fell once per year ranged from 21.2% to 26.3%, and who fell 2 or more times from 0.7% to 5%. A reduction in the rate of falls during the periods of activity was found. Mean attendance ranged from 75 to 83%. No significant relationship was found between attendance or age and the falls. Conclusions The reduced incidence of falls in the study and the reduction of the incidence rate during activity periods are used to propose a Geriatric Revitalization Program as an interesting and economical tool in preventing disability and maintaining quality of life in the elderly(AU)

Influencia de las radiaciones solares en la densidad mineral ósea de una población de personas mayores de Salamanca / Influence of the sunlight on bone mineral density in an elderly population of Salamanca

Introducción. Este estudio tiene como objetivocomprobar las variaciones de la densidad mineral ósea(DMO) de personas mayores activas que residen enSalamanca desde octubre hasta junio y desde juniohasta septiembre durante un período de dos añosconsecutivos, y si estas variaciones se correlacionancon las horas de sol durante estos meses.Pacientes y métodos. Se midió la DMO de un total de143 mujeres y 28 hombres, con un densitómetro deultrasonidos que abordaba el hueso calcáneo del piederecho, en octubre de 2003, junio de 2004, octubrede 2004, junio de 2005 y octubre de 2005.Resultados. Los resultados obtenidos fueron unadisminución significativa de la DMO en los dosperíodos comprendidos entre octubre y junio y unaumento significativo durante los meses de junio aseptiembre de 2004. También existe una correlaciónsignificativa entre el número total de horas de soly la DMO en hombres y el número de horas de sol y laDMO en la población sin osteoporosis ni osteopenia.Conclusiones. Se concluye que la DMO de las personasmayores activas de Salamanca recogidas en nuestroestudio disminuye durante los meses de menos horasde sol y aumenta durante los meses de verano y queparece existir una relación entre estos cambios y lashoras totales de sol en estos períodos

Introduction. This survey has aimed to assess variationsin bone mineral density (BMD) of active elderly peopleliving in Salamanca between October and June and Juneand September during two consecutive years and if thesecorrelated with the hours of sunlight during these months.Patients and methods. BMD was measured with anultrasound densitometer in the bone calcaneus of the rightfoot in October 2003, June 2004, October 2004, June2005 and October 2005 in a total of 143 women and28 men.Results. The results obtained show a significant decreasein BMD in both periods between October and June and asignificant increase during the months of June toSeptember of 2004. There is also a significant correlationbetween the total number of hours of sunlight and BMDin men and the number of hours of sun and BMD in thepopulation without osteoporosis or osteopenia.Conclusions. It is concluded that BMD of the activeelderly people of Salamanca of our study decreases duringthe months of fewer hours of sun and increases during themonths of summer and that relationship between thesechanges and the total hours of sun in these periods seemsto exist (AU)

Propuesta de un protocolo de fisioterapia en el impingement interno del hombro / Proposal of a physical therapy protocol in the internal shoulder impingement

El síndrome de impingement o pinzamiento interno es una patología frecuente en el hombro del deportista que realiza lanzamientos. Se describió por primera vez en 1991; sin embargo, no ha sido hasta hace 3 o 4 años, principalmente con el avance de la artroscopia de hombro, cuando se ha comenzado a introducir en los diagnósticos médicos y fisioterápicos. El objetivo de este estudio es proponer unas pautas de actuación fisioterápica en el tratamiento de este síndrome. Para ello, se somete a valoración a 2 pacientes diagnosticados de impingement interno y tratados mediante un protocolo fisioterápico justificado en función de la fisiopatología de la lesión y de las estructuras implicadas. Los resultados obtenidos se resumen en un hombro funcional para el gesto del lanzamiento, y por tanto para el deporte, validando así las pautas propuestas

The impingement symptom is a frequent pathology in sportsmen's shoulders which realize the gesture of throwing. It was described the first time in 1991; however, it wasn't until three or four years ago, mainly through arthroscopic surgery, when it started to appear in medical and physiotherapeutic diagnostics. The objective of the study is to propose guidelines for the correct physiotherapeutic treatment of this syndrome. For this study, 2 patients diagnosed impingement have been evaluated and treated under the physiotherapeutic protocol adapted to the physiopathology of the injury and the structures implied. The results obtained in a functional shoulder that realizes the gesture of throwing, and in consequence sports, prove the efficiency of the guidelines proposed

Eficacia de la fisioterapia en la enfermedad de Parkinson / Effectiveness of Physiotherapy in Parkinson's disease

La enfermedad de Parkinson se presenta como uno de los cuadros neurológicos más frecuentes en las personas mayores de 65 años. Produce numerosas alteraciones en el movimiento y la postura, evolucionando de forma lenta y progresiva y provocando diversas deficiencias en los pacientes afectados. Con este artículo se pretende comprobar la eficacia de la fisioterapia basada en la evidencia en el tratamiento de la enfermedad de Parkinson. Para ello se realiza una revisión bibliográfica de los textos publicados en los últimos siete años, tanto en bases de datos como publicaciones especializadas. Obteniendo escasas referencias y unos resultados poco significativos, concluyendo en la necesidad de un mayor control científico en los ensayos que se realicen (AU)

Tratamiento fisioterápico en las apofisitis del calcáneo en futbolistas jóvenes / Physiotherapy treatment in calcaneal apophysitis in young footballers

Introducción: El elevado número de casos de apositis del calcáneo (afección del núcleo de osificación secundario del calcáneo, Danowski 1992) que aparecen en jóvenes deportistas y la incapacidad que esta produce para la práctica deportiva, justifica la sistematización de un programa de actuación fisioterápica encaminado a tratar esta patología. Materialy método: El propósito del trabajo es valorar la eficacia de un programa de actuación fisioterápica para el tratamiento de esta patología. Se cuenta con una población de casi 200 deportistas que pertenecen a una Escuela de Fútbol, con edades comprendidas entre los 7 y los 16 años, y que entrenan 3 días a la semana (1,5 horas/día) y un partido de competición los fines de semana. El programa de tratamiento fisioterápico se diseña a partir de la utilización de medidas antinflamatorias, descontracturantes, de corrección del patrón de marcha y carrera y de corrección de los trastornos estáticos pretendiéndose eliminar los signos y síntomas que presenta dicho síndrome. Se aplica el programa a todos los casos de apofisitis del calcáneo que aparecen durante las temporadas 96-97 y 97-98. Resultados: Se registran 22 casos de apofisitis del calcáneo en una población entre los 7 y los 13 años, de los que el 68 por ciento fueron casos unilaterales. Tras la aplicación del programa de fisioterapia se obtuvieron buenos resultados en el 63,6 por ciento de los casos, en los que desaparecieron los signos y síntomas . En el 9 por ciento de los mismos aparecieron recidivas durante la misma temporada. Y en un 27 por ciento la evolución fue desconocida. Conclusión: El tratamiento fisioterápico puede calificarse de eficaz ya que mantiene al deportista realizando su actividad física normal y elimina los signos y sítomas de la afección en un corto período de tiempo y con buenos resultados (AU)