Brillouin frequency shift of standard optical fibers set in water vapor medium

The dependence of the Brillouin frequency shift (BFS) on UV-cured acrylate coating and uncoated fibers for media that have different water vapor concentrations is experimentally investigated. The BFS is proportional to the temperature within the fiber, but it also depends on the water vapor contained in the surroundings of the fiber. A hypothesis based on the efficiency of the heat transfer due to the different humidity concentration in the media is proposed, and the temperature difference that depends on the heat transfer is quantified in standard fibers. A shift of ∼0.22 MHz for relative humidity change between 60% and 98% at 20°C is measure

Efficient dynamic events discrimination technique for fiber distributed Brillouin sensors

A technique to detect real time variations of temperature or strain in Brillouin based distributed fiber sensors is proposed and is investigated in this paper. The technique is based on anomaly detection methods such as the RX-algorithm. Detection and isolation of dynamic events from the static ones are demonstrated by a proper processing of the Brillouin gain values obtained by using a standard BOTDA system. Results also suggest that better signal to noise ratio, dynamic range and spatial resolution can be obtained. For a pump pulse of 5 ns the spatial resolution is enhanced, (from 0.541 m obtained by direct gain measurement, to 0.418 m obtained with the technique here exposed) since the analysis is concentrated in the variation of the Brillouin gain and not only on the averaging of the signal along the time

Desarrollo del proyecto y ejecución de las fachadas del Museo Guggenheim Bilbao. Bilbao/España

This paper describes in detail the project process and the execution of the façades, blind and of glass, of the Guggenheim Bilbao Museum; also the problems that have been overcome to achieve the unique revetment of the nine modules of the building, and the solutions that were adopted.En esta comunicación se describe, pormenorizadamente, el proceso seguido en el proyecto y la ejecución de las fachadas ciegas y acristaladas del Museo Guggenheim Bilbao. Se exponen los problemas que surgieron para resolver la singular envoltura de los nueve módulos que componen el edificio y cuáles fueron las soluciones adoptadas

Clinical study of cervicogenic headache

The cervicogenic headache was studied to get a deeper insight into the pathogenetic mechanisms, and clinical presentation forms. Material and Methods. Eleven female patients, ranging from 34 to 81 years-old, with cervicogenic headaches, were studied and correlated with NMR images of the cervical spine. Results. Intense neck pain irradiated to parietal, occipital, temporal regions, and shoulders were correlated with NMR images of the degenerated cervical spine. Also, lumbar spine pathology, osteoporosis, gallstones, and cholecystitis were found. The following associated neurological, neurobehavioral, and metabolic diseases comorbidities were observed, such as blood hypertension, diabetes, obesity, hypothyroidism, partial epilepsy, tremor, familial stress, memory, sleep disorders, and dizziness. Also, we found mixed cervicogenic headaches and migraines in 50% of cases studied. Conclusion. The headache and the associated images of cervical pathology have been clinically interpreted as cardinal signs of cervicogenic headache. A mixed cervicogenic mixed type was observed

Analysis of genetic variability and mapping of point mutations in influenza virus by the RNase A mismatch cleavage method

We have applied the RNase A mismatch cleavage method to analyze genetic variability in RNA viruses by using influenza virus as a model system. Uniformly labeled RNA probes synthesized from a cloned hemagglutinin gene of a given viral strain were hybridized to RNA isolated from other strains of characterized or uncharacterized genetic composition. The RNA.RNA heteroduplexes containing a variable number of base mismatches were digested with RNase A, and the resistant products were analyzed by denaturing polyacrylamide gel electrophoresis. We show that many of these single base mismatches are cleaved by RNase A, generating unique and characteristic patterns of resistant RNA fragments specific for each of the different viral strains. Comparative analysis of the cleavage patterns allows a qualitative estimation of the genetic relatedness and evolution of field strains. We also show that cleavage by RNase A at single base mismatches can readily detect and localize point mutations present in monoclonal antibody-resistant variants. This method should have wide applications in the study of RNA viruses, not only for epidemiological analysis but also in some diagnostic problems, such as characterization of phenotypic mutants.This work was supported by National Institutes of Health Grant CA33021 awarded by the Nationa l Cancer Institute to M.P. and by grants from the Comision Asesora de Investigacion Cientificay Tecnica (Grant 608/438) and Fondo de Investigaciones Sanitarias to J.O. and J.A.M.C.L.-G. was a recipient of a NATO short-term post doctoral fellow-ship while on leave from the Centro Nacional de Microbiologia, Majadahonda, Madri

Anisotropic magnetotransport realized in doped hematite

Conventional antiferromagnetic materials have long been recognized for their time-reversal symmetry, resulting in a zero anomalous Hall coefficient. However, a paradigm shift occurs when examining easy-axis antiferromagnets and their spin-flop transition. This transition introduces a magnetic canted moment, leading to the emergence of a non-zero anomalous Hall signal and the generation of a non-dissipative transversal current. While high symmetry systems typically manifest an isotropic Hall effect, our study unveils the extraordinary behavior exhibited by hematite that becomes conductive due to small Ti doping. We investigate the magnetotransport in Titanium-doped hematite, uncovering a highly pronounced and unconventional symmetry. Notably, this effect displays a remarkable dependence on the crystal orientation of the material. We establish a compelling correlation between our experimental observations and the predicted anomalous Hall effect in altermagnets through symmetry analysis. This study expands our understanding of the Hall effect in antiferromagnetic materials and sheds light on the intricate interplay between crystal orientation and unconventional Hall phenomena

Substitutional doping of hybrid organic-inorganic perovskite crystals for thermoelectrics

Hybrid organic–inorganic perovskites have generated considerable research interest in the field of optoelectronic devices. However, there have been significantly fewer reports of their thermoelectric properties despite some promising early results. In this article, we investigate the thermoelectric properties of bismuth-doped CH3NH3PbBr3 (MAPbBr3) single crystals. The high-quality Bi-doped crystals were synthesized by inverse temperature crystallization and it was found that Bi substitutes onto the B-site of the ABX3 perovskite lattice of MAPbBr3 crystals with very little distortion of the crystal structure. Bi doping does not significantly alter the thermal conductivity but dramatically enhances the electrical conductivity of MAPbBr3, increasing the charge carrier density by more than three orders of magnitude. We obtained a negative Seebeck coefficient of −378 μV K−1 for 15% (x = 0.15) Bi-doped MAPb(1−x)BixBr3 confirming n-type doping and also measured the figure of merit, ZT. This work highlights routes towards controlled substitutional doping of halide perovskites to optimise them for thermoelectric applications

control gestión en prácticas profesionales y normativa de pasantías universitarias. caso: coordinación práctica profesional DAC-UCLA

The University as a knowledge generating institution has developed optimal management tools for academic competitiveness and to satisfy the environment, which demands qualified professionals to face the disagreements of business dynamics. The Coordination of Professional Practices of DAC-UCLA provides the labor market with interns capable of solving problems immersed in business dynamics, for which it is necessary to control their management, for which the University Internship Regulations were approved as a mechanism; in this sense, the need arose to carry out this study to know the link between this legal framework and the management processes. This research was conducted during the academic period 2009-2 and 2011-1. It was a qualitative approach work, non experimental level, descriptive and documentary type, a formal interview was used as a collection instrument. The relevance of this research was to achieve a strategic diagnosis where the lack of a long-term management philosophy was concluded, since the management is characterized by being proactive, with team culture, in addition to a value system based on beliefs. The components of the regulations are legally established, although the structure of the Coordination is not formally established as a unit of the DAC, and the control processes are developed in an incipient manner. The study of strategic and management control allowed to make recommendations such as developing a strategic planning for the unit, formalization of organizational manuals, functions, positions and procedures as well as control mechanisms and the approval of the coordination as a functional unit of the DAC.La Universidad como institución generadora de conocimiento ha desarrollado herramientas de gestión óptimas para la competitividad académica y para satisfacer el entorno, el cual demanda profesionales aptos para enfrentar las desavenencias de la dinámica empresarial. La Coordinación de Prácticas Profesionales del DAC-UCLA provee al mercado laboral de pasantes capaces de solventar problemas inmersos en la dinámica empresarial, por lo que es necesario controlar su gestión, para ello se aprobó como mecanismo la Normativa de Pasantía Universitaria; en tal sentido se originó la necesidad de realizar este estudio para conocer la vinculación de ese marco legal con los procesos de gestión. Esta investigación se realizó durante el lapso académico 2009-2 y 2011-1. Fue un trabajo de enfoque de tipo cualitativo, nivel no experimental, tipo descriptiva y documental, se empleó una entrevista formal como instrumento de recolección. La relevancia de esta investigación fue lograr realizar un diagnóstico estratégico donde se concluyó la carencia de una filosofía de gestión proyectada a largo plazo, ya que la gestión se caracteriza por ser proactiva, con cultura de equipo, además de un sistema de valores basado en creencias. Los componentes de la normativa están establecidos jurídicamente, no obstante la estructura de la Coordinación no está formalmente establecida como unidad del DAC, y los procesos de control están desarrollados de manera incipiente. El estudio del control estratégico y de gestión permitió conformar recomendaciones como desarrollar una planificación estratégica para la unidad, formalización de manuales de organización, funciones, cargos y procedimientos además de mecanismos de control y la aprobación de la coordinación como una unidad funcional del DAC