78 research outputs found
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
Kirigami-Inspired Organic and Inorganic Film-Based Flexible Thermoelectric Devices with Built-In Heat Sink
Thermoelectric (TE) devices can convert heat to electricity directly, which offers a unique opportunity to realize waste heat recovery. However, conventional TE devices inevitably use heat sinks, which are bulky, rigid and heavy, limiting practical applications. Herein, we propose a fully integrated film-based TE device with intrinsically built-in fins as heat sink in a hexagonal honeycomb device structure, that simultaneously achieves high TE performance and conformability, as confirmed by experiments and modelling. A flexible Kapton substrate with copper electrodes, integrating either carbon nanotube (CNT) veils or bismuth telluride (Bi2Te3) TE ‘legs’, both of n- and p-type, achieved a remarkable specific power of 185.4 nW K−2 for a Bi2Te3-based device and 53.1 nW K−2 for a CNT-based device, thanks to the heat dissipation effect granted by the built-in fins. Besides, the addition of oriented polymer films interconnects, contracting when above their glass transition temperature, allowed a single substrate two-dimensional (2D) TE device to self-fold into a three-dimensional (3D) hexagonal honeycomb structure, with built-in fins, contactlessly and autonomously. The demonstrated shape-programmed kirigami-inspired scalable TE device paves the way for realising self-powered applications comprising hundreds of TE legs with both inorganic (e.g., Bi2Te3) and organic (e.g. CNT veils) TE materials and integrated heat sinks
Magnetic properties of hematite revealed by an ab initio parameterized spin model
Hematite is a canted antiferromagnetic insulator, promising for applications
in spintronics. Here, we present ab initio calculations of the tensorial
exchange interactions of hematite and use them to understand its magnetic
properties by parameterizing a semiclassical Heisenberg spin model. Using
atomistic spin dynamics simulations, we calculate the equilibrium properties
and phase transitions of hematite, most notably the Morin transition. The
computed isotropic and Dzyaloshinskii--Moriya interactions result in a N\'eel
temperature and weak ferromagnetic canting angle that are in good agreement
with experimental measurements. Our simulations show how dipole-dipole
interactions act in a delicate balance with first and higher-order on-site
anisotropies to determine the material's magnetic phase. Comparison with
spin-Hall magnetoresistance measurements on a hematite single-crystal reveals
deviations of the critical behavior at low temperatures. Based on a mean-field
model, we argue that these differences result from the quantum nature of the
fluctuations that drive the phase transitions.Comment: 11 pages, 10 figure
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
The Association Between Persistent Poverty and Melanoma Mortality in Texas: A Retrospective Study Using Texas Cancer Registry Data
https://openworks.mdanderson.org/sumexp22/1123/thumbnail.jp
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
Optimization of a Low Cost and Broadly Sensitive Genotyping Assay for HIV-1 Drug Resistance Surveillance and Monitoring in Resource-Limited Settings
Commercially available HIV-1 drug resistance (HIVDR) genotyping assays are expensive and have limitations in detecting non-B subtypes and circulating recombinant forms that are co-circulating in resource-limited settings (RLS). This study aimed to optimize a low cost and broadly sensitive in-house assay in detecting HIVDR mutations in the protease (PR) and reverse transcriptase (RT) regions of pol gene. The overall plasma genotyping sensitivity was 95.8% (N = 96). Compared to the original in-house assay and two commercially available genotyping systems, TRUGENE® and ViroSeq®, the optimized in-house assay showed a nucleotide sequence concordance of 99.3%, 99.6% and 99.1%, respectively. The optimized in-house assay was more sensitive in detecting mixture bases than the original in-house (N = 87, P<0.001) and TRUGENE® and ViroSeq® assays. When the optimized in-house assay was applied to genotype samples collected for HIVDR surveys (N = 230), all 72 (100%) plasma and 69 (95.8%) of the matched dried blood spots (DBS) in the Vietnam transmitted HIVDR survey were genotyped and nucleotide sequence concordance was 98.8%; Testing of treatment-experienced patient plasmas with viral load (VL) ≥ and <3 log10 copies/ml from the Nigeria and Malawi surveys yielded 100% (N = 46) and 78.6% (N = 14) genotyping rates, respectively. Furthermore, all 18 matched DBS stored at room temperature from the Nigeria survey were genotyped. Phylogenetic analysis of the 236 sequences revealed that 43.6% were CRF01_AE, 25.9% subtype C, 13.1% CRF02_AG, 5.1% subtype G, 4.2% subtype B, 2.5% subtype A, 2.1% each subtype F and unclassifiable, 0.4% each CRF06_CPX, CRF07_BC and CRF09_CPX
Resposta dinâmica de estruturas na direção da velocidade média do vento
Neste trabalho apresenta-se um procedimento para a determinação da resposta dinâmica na direção da velocidade média, de estruturas sujeitas à ação do vento turbulento. Este procedimento está baseado no método do espectro, no qual caracteriza-se estatisticamente as propriedades da turbulgncia. O seu principal objetivo é o de facilitar a consideração do efeito dinâmico do vento em Normas sobre cargas nas construções. Ensaios em túnel de vento sobre um modelo aeroelástico foram realizados com a finalidade de comparar resultados teóricos e experimentais. Discute-se finalmente a validade e limitações do método proposto.A procedure to determine the along-wind dynamic response of structures subjected to turbulent wind action i s developed in this thesis. The method follows from the statistical description of the characteristics of the atmospheric turbulence. Its main objective is the developement of a code-oriented solution procedure. In order to verify the theorical predictions, wind tunnel tests were performed on an aeroelastic model. The applicability and limitations of the proposed method are fully discussed
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