Comparison of muscle strategies between two different age groups in the sitting-to-standing movement

Investigar a ordem de ativação dos músculos tibial anterior (TA), reto femoral (RF), gastrocnêmio medial (GM), bíceps femoral (BF) e paravertebral lombar (PL) no movimento de passar de sentado para em pé comparando dois grupos etários diferentes. Sujeitos: Grupo A: vinte sujeitos com idade entre 25 à 35 anos, saudáveis, e o Grupo B: vinte sujeitos com idade entre 60 à 65 anos, sem patologias neurológicas associadas e sem histórico de quedas nos últimos 6 meses. O Teste de Berg, um eletrogoniômetro bidimensional flexível foi usado para marcar o início do movimento articular, no quadril e joelho do mesmo lado. O tempo total do movimento no grupo A foi menor de olhos abertos do que de olhos fechados. O grupo B em relação às duas condições não houve diferença estatística no tempo total da execução da tarefa (p< 0,05). A análise de variância de 1 fator foi usada para comparar a ordem de ativação muscular, e os resultados demonstraram que a ordem de ativação foi diferente no grupo A e no grupo B de olhos abertos e semelhante na condição de olhos fechados. O tibial anterior foi o primeiro músculo a ser ativado nos dois grupos e nas duas condições e os demais músculos tiveram ordem de ativação diferente; o tempo total de movimento foi menor no grupo A; a ausência momentânea da visão influenciou mais o grupo A do que o grupo B.To investigate the activation sequence of the tibialis anterior muscle (AT), the rectus femoris muscle (RF), the medial gastrocnemius muscle (MG), the biceps femoris muscle, and the paravertebral lumbar muscle (PL) in the movement from sitting to standing position as com-pared between two different age groups. Subjects: Group A: twenty healthy subjects between 25 and 35 years of age, and Group B: twenty subjects between 60 and 65 years of age with no associated neurologi-cal pathologies and no history of falls for the preceding six months.  In group A the total time of movement was less with eyes open than with eyes closed. For group B, the difference in the total task execution time was not statistically significant for the two conditions (p < 0.05). The one-way analysis of variance was used to compare the muscle activation sequences, and the results demon-strate that this sequence was different between group A and group B with eyes open and similar with eyes closed. The tibialis anterior was the first muscle to be activated in both groups in both conditions, but the other muscles had a different activation sequence; the total time of movement was less in group A; the momentary absence of vision influenced group A more than group B

Características morfológicas de la pars de C2 de humanos

OBJETIVO: avaliar a morfometria da pars da segunda vértebra cervical, verificar as variações existentes e predizer sua segurança para a colocação de parafusos por meio de uma abordagem cervical posterior. MÉTODOS: 58 vértebras foram obtidas para estudo anatômico (116 pars de C2) e foram medidas a altura e largura da pars, além do comprimento eixo-pedículo, largura e comprimento do pedículo, angulação sagital e medial. Todas as medidas foram separadas quanto aos seus lados direito e esquerdo; foi realizado o cálculo da média, variação, desvio padrão e a médica foi comparada com os estudos prévios. RESULTADOS: a largura média da pars de C2 foi de 9,5 mm; a altura, 9,5 mm; não houve diferença significativa entre os lados esquerdo e direito. O comprimento médio do pedículo foi de 10,5 mm; a medida média encontrada para o comprimento eixo-pedículo foi de 24,9 mm; a largura do pedículo foi de 2,8 mm. A angulação sagital encontrada foi de 19,6º e a horizontal foi de 28,5º. CONCLUSÕES: este estudo demonstra a viabilidade para a colocação de parafuso na pars de C2 em uma população caucasiana, destacando-se, porém, a grande variabilidade anatômica encontrada nas referidas medidas.OBJECTIVE: to evaluate de morphometry of the pars of the second cervical vertebra, assess the variations existent and predict its safety for the placement of screws through a posterior cervical approach. METHODS: 58 vertebrae were obtained for anatomic study (116 pars of C2) and measured the height and width of the pars, besides the length of the axis-pedicle, width and length of the pedicle, sagittal and medial angulations. All measurements were separated as to their right and left sides, completed the calculation of media, variation, standard deviation and compared to previous studies. RESULTS: the medium width of the pars of C2 was 9,5 mm, the height, 9,5 mm, without significant difference between right and left sides. The medium length of the pedicle was 10.5 mm and the medium measurement found for the length axis-pedicle was of 24.9 mm and the width of the pedicle was of 2.8 mm. The sagittal angulation found was of 19.6º and the horizontal was of 28.5º. CONCLUSIONS: this study demonstrates the viability of positioning screws in the pars of C2 in a Caucasian population, emphasizing, however, the great anatomic variability found in the referred measurements.OBJETIVO: evaluar la morfometría de la pars de la segunda vértebra cervical, verificar las variaciones existentes y predecir su seguridad para la colocación de los tornillos por un abordaje cervical posterior. MÉTODOS: 58 vértebras fueron obtenidas para el estudio anatómico (116 pars de C2) y fueron medidas su altura y el ancho de las pars, además de la largura eje-pedículo, ancho y largura del pedículo, ángulo sagital y medial. Todas las medidas fueron separadas según sus lados derecho e izquierdo, se realizó el cálculo de la media, variación, desvío estándar y comparados los valores con estudios previos. RESULTADOS: el ancho promedio de la pars de C2 fue de 9.5 mm, la altura de 9.5 mm, sin diferencia significativa entre los lados izquierdo y derecho. La largura promedio del pedículo fue de 10.5 mm y la medida promedio encontrada para la largura eje-pedículo fue de 24.9 mm, además del ancho del pedículo que fue de 2.8 mm. El ángulo sagital encontrado fue de 19.6° y de la horizontal de 28.5°. CONCLUSIÓN: este estudio demuestra la viabilidad para la colocación de tornillos en la pars de C2 en una población caucásica, pero destacándose la gran variabilidad anatómica encontrada en las medidas referentes

Investigating multiple elves and halos above strong lightning with the fluorescence detectors of the Pierre Auger Observatory

ELVES are being studied since 2013 with the twenty-four FD Telescopes of the Pierre Auger Observatory, in the province of Mendoza (Argentina), the world’s largest facility for the study of ultra-high energy cosmic rays. This study exploits a dedicated trigger and extended readout. Since December 2020, this trigger has been extended to the three High levation Auger Telescopes (HEAT), which observe the night sky at elevation angles between 30 and 60 degrees, allowing a study of ELVES from closer lightning. The high time resolution of the Auger telescopes allows us to upgrade reconstruction algorithms and to do detailed studies on multiple ELVES. The origin of multiple elves can be studied by analyzing the time difference and the amplitude ratio between flashes and comparing them with the properties of radio signals detected by the ENTLN lightning network since 2018. A fraction of multi-ELVES can also be interpreted as halos following ELVES. Halos are disc-shaped light transients emitted at 70-80 km altitudes, appearing at the center of the ELVES rings, due to the rearrangement of electric charges at the base of the ionosphere after a strong lightning event

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations