Application of a wavelet technique for the detection of earthquake signatures in the geomagnetic field

We developed an algorithm especially adapted to <i>single-station </i>wavelet detection of geomagnetic events, which precede or accompany the earthquakes. The detection problem in this situation is complicated by a great variability of earthquakes and accompanied phenomena, which aggravates finding characteristic features of the events. Therefore we chose to search for the characteristic features of both &quot;disturbed&quot; intervals (containing earthquakes) and &quot;quiet&quot; recordings. In this paper we propose an algorithm for solving the problem of detecting the presence of signals produced by an earthquake via analysis of its signature against the existing database of magnetic signals. To achieve this purpose, we construct the magnetic signature of certain earthquakes using the distribution of the energies among blocks, which consist of wavelet packet coefficients

Noise-based Correction for Electrical Impedance Tomography

Introduction. Noisy measurements frequently cause noisy and inaccurate images in impedance imaging. No post-processing technique exists to calculate the propagation of measurement noise and use this to suppress noise in the image. Objectives. The objectives of this work were (1) to develop a post-processing method for noise-based correction (NBC) in impedance tomography, (2) to test whether NBC improves image quality in electrical impedance tomography (EIT), (3) to determine whether it is preferable to use correlated or uncorrelated noise for NBC, (4) to test whether NBC works with in vivo data and (5) to test whether NBC is stable across model and perturbation geometries. Methods. EIT was performed in silico in a 2D homogeneous circular domain and an anatomically realistic, heterogeneous 3D human head domain for four perturbations and 25 noise levels in each case. This was validated by performing EIT for four perturbations in a circular, saline tank in 2D as well as a human head-shaped saline tank with a realistic skull-like layer in 3D. Images were assessed on the weighted spatial variance (WSV) with respect to the target image. The effect of NBC was also tested for example in vivo EIT data of lung ventilation in a human thorax and cortical activity in a rat brain. Results. On visual inspection, NBC maintained or increased image quality for all perturbations and noise levels in 2D and 3D experimentally and in silico. Analysis of the WSV showed that NBC significantly improved the WSV in nearly all cases. When the WSV was inferior with NBC, this was either visually imperceptible or a transformation between noisy images. For in vivo data, NBC improved image quality in all cases and preserved the expected shape of the reconstructed perturbation. In practice, uncorrelated NBC performed better than correlated NBC and is recommended as a general-use post-processing technique in EIT.Comment: 23 pages, 13 figure

Israel in der Olympischen Bewegung

Die Olympische Bewegung und die Zionistische Bewegung wurden beide im letzten Jahrzehnt des 19. Jahrhunderts in Europa gegründet und standen lange in einem schwierigen Verhältnis zueinander. Die vorliegende Arbeit befasst sich mit gesellschaftlichen, politischen und ideologischen Fragen, die die Zionistische Bewegung und den Staat Israel beim Aufbau nationaler Sportinstitutionen und bei der Vertretung des israelischen Sports auf internationaler Ebene betreffen. Der Schwerpunkt liegt auf den Bemühungen eines Olympischen Komitees des jüdischen Gemeinwesens in Palästina zur Zeit des Britischen Mandats, die Anerkennung durch das Internationale Olympische Komitee zu erwirken, der Gründung des NOK von Palästina im Jahre 1934, dessen Nichtteilnahme an den Olympischen Spielen 1936, sowie den Auseinandersetzungen um die Anerkennung des Israelischen Olympischen Komitees in den Jahren 1948-1952. Die Beziehungen zwischen der Olympischen Bewegung und dem Staat Israel standen mehr als 40 Jahre lang im Schatten internationaler Konflikte, die die Teilnahme israelischer Sportler an den Asienspielen beendete und an den Mittelmeerspielen verhinderte. Insbesondere die Entwicklungen und Ereignisse im Nahen Osten, wie z.B. die Kriege mit arabischen Nachbarstaaten 1956, 1967 und 1973, sowie der Angriff palästinensischer Terroristen auf die israelische Mannschaft bei den Olympischen Spielen 1972 in München wirkten sich auf die internationalen Sportbeziehungen Israels aus. Die antisowjetische Orientierung der israelischen Außenpolitik führte schließlich zum Boykott der Olympischen Spiele 1980 in Moskau. Erst 1994 normalisierte sich das Verhältnis zwischen der Olympischen Bewegung und Israel, nachdem die israelischen Sportverbände in die europäischen Sportstrukturen eingegliedert worden waren. Zum ersten Mal wurde auch ein Israeli in das IOC gewählt. The Olympic Movement and the Zionist Movement were both founded in Europe in the final decade of the 19th century and long had a difficult relationship with each other. The work at hand addresses the social, political and ideological questions that relate to the Zionist Movement and the State of Israel in respect of the establishment of national sports institutions and the representation of Israeli sport at international level. The dissertation focuses on the endeavours undertaken by an Olympic Committee of the Jewish Community in Palestine during the British Mandate to gain recognition by the International Olympic Committee, the founding of the NOC for Palestine in 1934, its non-participation in the Olympic Games of 1936, and the conflicts over the recognition of the Israeli Olympic Committee from 1948 to 1952. Relations between the Olympic Movement and the State of Israel were overshadowed by international conflicts for 40 years that then prevented the participation by Israeli athletes in the Asian Games and the Mediterranean Games. It was developments and incidents in the Middle East, in particular, such as the wars with neighbouring Arab states in 1956, 1967 and 1973, and the attack by Palestinian terrorists on the Israeli team at the Olympic Games of 1972 in Munich that influenced Israel's international sporting relations. The anti-Soviet orientation taken by Israel's foreign policy eventually led to the boycott of the Olympic Games held in Moscow in 1980. Only in 1994 did relations between the Olympic Movement and Israel return to normal after the Israeli sports federations had been integrated into the Europe sports structures. An Israeli was also elected onto the IOC for the first time

Controlling the spin orientation of photoexcited electrons by symmetry breaking

We study reflection of optically spin-oriented hot electrons as a means to probe the semiconductor crystal symmetry and its intimate relation with the spin-orbit coupling. The symmetry breaking by reflection manifests itself by tipping the net-spin vector of the photoexcited electrons out of the light propagation direction. The tipping angle and the pointing direction of the net-spin vector are set by the crystal-induced spin precession, momentum alignment and spin-momentum correlation of the initial photoexcited electron population. We examine non-magnetic semiconductor heterostructures and semiconductor/ferromagnet systems and show the unique signatures of these effects.Comment: 4 pages, 3 figures, resubmitte

Cuando la identidad está en riesgo: Musicoterapia, Cultura y Migración en el Hospital Público Pediátrico

Dentro de la Escuela Hospitalaria, institución que funciona en el contexto del Hospital Público Pediátrico de Buenos Aires, encontramos numerosos pacientes internados que proceden de otras provincias o países limítrofes. El desconocimiento de la cultura del “otro” por parte de médicos, enfermeros y docentes, redunda frecuentemente en una situación de marginación y aculturación para el paciente. A través de la música, se trabajará en el proceso de reconstrucción dinámica de la identidad del niño, que se ve amenazada por la doble situación de desarraigo inherente a la migración y a la hospitalización

A fourth-order Runge-Kutta in the interaction picture method for coupled nonlinear Schrodinger equation

A fourth-order Runge-Kutta in the interaction picture (RK4IP) method is presented for solving the coupled nonlinear Schrodinger equation (CNLSE) that governs the light propagation in optical fibers with randomly varying birefringence. The computational error of RK4IP is caused by the fourth-order Runge-Kutta algorithm, better than the split-step approximation limited by the step size. As a result, the step size of RK4IP can have the same order of magnitude as the dispersion length and/or the nonlinear length of the fiber, provided the birefringence effect is small. For communication fibers with random birefringence, the step size of RK4IP can be orders of magnitude larger than the correlation length and the beating length of the fibers, depending on the interaction between linear and nonlinear effects. Our approach can be applied to the fibers having the general form of local birefringence and treat the Kerr nonlinearity without approximation. For the systems with realistic parameters, the RK4IP results are consistent with those using Manakov-PMD approximation. However, increased interaction between the linear and nonlinear terms in CNLSE leads to increased discrepancy between RK4IP and Manakov-PMD approximation.Comment: 12 pages, 4 figures, 1 Table, submitted to Optics Express

Magnetically induced spin-dependent photoemission from p-GaAs(Cs,O) into vacuum

A spin-dependent emission of optically oriented electrons from p-GaAs(Cs,O) into vacuum was experimentally observed in a magnetic field normal to the surface. This phenomenon is explained within the model which takes into account the jump in the electron g factor at the semiconductor-vacuum interface. Due to this jump, the effective electron affinity on the semiconductor surface depends on the mutual direction of optically oriented electron spins and the magnetic field, resulting in the spin-dependent photoemission. It is demonstrated that the observed effect can be used for the determination of spin diffusion length in semiconductors.Comment: 7 pages, 6 figures, published versio