Role of substrate quality on the performance of semipolar (11 2 - 2) InGaN light-emitting diodes

We compare the optical properties and device performance of unpackaged InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) emitting at ∼430 nm grown simultaneously on a high-cost small-size bulk semipolar (11 2 - 2) GaN substrate (Bulk-GaN) and a low-cost large-size (11 2 - 2) GaN template created on patterned (10 1 - 2) r-plane sapphire substrate (PSS-GaN). The Bulk-GaN substrate has the threading dislocation density (TDD) of ∼ and basal-plane stacking fault (BSF) density of 0 cm-1, while the PSS-GaN substrate has the TDD of ∼2 × 108cm-2 and BSF density of ∼1 × 103cm-1. Despite an enhanced light extraction efficiency, the LED grown on PSS-GaN has two-times lower internal quantum efficiency than the LED grown on Bulk-GaN as determined by photoluminescence measurements. The LED grown on PSS-GaN substrate also has about two-times lower output power compared to the LED grown on Bulk-GaN substrate. This lower output power was attributed to the higher TDD and BSF density.

Biståndshandläggare inom äldreomsorgens upplevelse av sin arbetssituation : En kvalitativ studie ur ett salutogent perspektiv

Syftet med denna uppsats var att genom ett salutogent perspektiv få en ökad förståelse för, inom äldreomsorgen verksamma, biståndshandläggares arbetssituation samt att undersöka vad som kan bidra till att biståndshandläggares arbetssituation upplevs som lättare och mindre påfrestande. Metoden som använts är kvalitativa intervjuer där sex biståndshandläggare verksamma i Värmland har intervjuats. Intervjuerna analyserades genom teman ur KASAM och resulterade i kategorier under varje tema. Under temat begriplighet framkom att biståndshandläggare får stöd från sina kollegor men att de också önskar att det fanns mer resurser för handledning. Biståndshandläggare utför mer än vad som ingår i arbetsbeskrivningen. Under temat hanterbarhet framgår att hög arbetsbelastning hanteras genom att biståndshandläggarna måste planera, strukturera och prioritera. Kollegornas stöd gör arbetet lättare att hantera då de genom att prata med varandra bearbetar känslomässigt påfrestande delar av arbetet. De uttryckte olika behov av att reflektera över sitt arbete. Biståndshandläggare har en stor frihet att planera sin egen arbetsdag och de samverkar med andra professioner. Under temat meningsfullhet framgår att biståndshandläggare finner mening i att göra skillnad för den enskilde. Vårt resultat visar att biståndshandläggarna är utsatta för stress i sitt arbete och att de också har förmåga att möta stressen, men förmågan att möta stressen minskar när arbetsbelastningen blir för hög. 

Posibilidades y limitaciones de la garantía de depósitos

Un sistema de garantía de depósitos puede contribuir a la estabilidad financiera, siempre que cuente con fondos adecuados y otros mecanismos de salvaguardia, como un sólido programa de supervisión bancaria. En la fábula de Esopo sobre la liebre y la tortuga, la tortuga aceptó echar una carrera con la liebre. La liebre, mucho más veloz que la tortuga, salió corriendo a toda velocidad en el primer tramo de la carrera, pero después se acostó a dormir una siesta, convencida de que podría adelantar a su contrincante. Cuando despertó, la tortuga, que había avanzado lentamente pero con constancia, se estaba acercando a la meta. La liebre no pudo alcanzar a la tortuga y ésta ganó la carrera. Un sistema de garantía de depósitos eficaz se asemeja más a una tortuga que a una liebre. A primera vista parece que puede establecerse rápidamente y con facilidad un sistema nacional de garantía de depósitos que anuncie una garantía pública para los depósitos de los bancos. Algunos países, a fin de evitar el retiro masivo de depósitos que podría llevar a la quiebra a los bancos en situación sólida y a fin de estabilizar un sistema bancario en dificultades, han intentado crear un sistema de garantía de depósitos de esta forma. Lamentablemente, a menos que el sistema cuente con fondos suficientes para hacer frente a una grave crisis financiera y con un sólido programa de supervisión bancaria, este sistema está destinado al fracaso

Mixture of time-dependent growth models with an application to blue swimmer crab length-frequency data

Understanding how aquatic species grow is fundamental in fisheries because stock assessment often relies on growth dependent statistical models. Length-frequency-based methods become important when more applicable data for growth model estimation are either not available or very expensive. In this article, we develop a new framework for growth estimation from length-frequency data using a generalized von Bertalanffy growth model (VBGM) framework that allows for time-dependent covariates to be incorporated. A finite mixture of normal distributions is used to model the length-frequency cohorts of each month with the means constrained to follow a VBGM. The variances of the finite mixture components are constrained to be a function of mean length, reducing the number of parameters and allowing for an estimate of the variance at any length. To optimize the likelihood, we use a minorization–maximization (MM) algorithm with a Nelder–Mead sub-step. This work was motivated by the decline in catches of the blue swimmer crab (BSC) (Portunus armatus) off the east coast of Queensland, Australia. We test the method with a simulation study and then apply it to the BSC fishery data.

La Participación comunitaria en la resolución de los problemas de salud parroquia Jerusalén. Cantón Biblián. Provincia del Cañar.1997

En el presente trabajo se parte de un marco teórico, que contempla los conceptos y principios básicos de la Atención Primaria de Salud [APS], de los Sistemas Locales de Salud [SILOS], poniendo énfasis en las formas de Participación Comunitaria por ser uno de los ejes principales en el que se sustenta la APS. Luego mediante la aplicación de la Participación Comunitaria en la parroquia Jerusalén, se obtuvieron los siguientes resultados: El equipo de salud logró concientizarse de los problemas existentes en la comunidad y se incorporó al trabajo comunitario con lo cual se ganó confianza, credibilidad y capacidad de asesoramiento; se identificó, reestructuró y conformó organizaciones comunitarias de acuerdo a las necesidades, con dichas organizaciones se realizó el Diagnóstico Participativo de Salud, que engloba: un censo poblacional y de migración mediante mapas parlantes elaborados por la comunidad, identificación de las patologías más frecuentes y de familias en riesgo y por último se priorizó y seleccionó como problema de acuerdo a la frecuencia, importancia y vulnerabilidad la falta de agua apta para el consumo. Para resolver este problema se utilizó una de las herramientas de la Gerencia de Calidad Total que es el Microproyecto, en donde la comunidad participó en la fase de Planificación, Ejecución y Evaluación, obteniéndose: El mejoramiento de los Conocimientos, Actitudes y Prácticas [CAPs] en la desinfección del agua mediante el método de clorificación; autogestión comunitaria para la compra de un equipo productor de cloro. Racionalización del consumo del agua, por último mediante la coordinación interinstitucional con el municipio del cantón Biblián y la Subsecretaría de Saneamiento Ambiental, se obtuvo una partida presupuestaria para la construcción del desarenador, la comunidad por su parte aportó con mano de obra a través de la organización de mingas.

Engineering thin films of magnetic alloys and semiconductor oxides at the nanoscale

The thesis aims to exploit properties of thin films for applications such as spintronics, UV detection and gas sensing. Nanoscale thin films devices have myriad advantages and compatibility with Si-based integrated circuits processes. Two distinct classes of material systems are investigated, namely ferromagnetic thin films and semiconductor oxides. To aid the designing of devices, the surface properties of the thin films were investigated by using electron and photon characterization techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffraction (GIXRD), and energy-dispersive X-ray spectroscopy (EDS). These are complemented by nanometer resolved local proximal probes such as atomic force microscopy (AFM), magnetic force microscopy (MFM), electric force microscopy (EFM), and scanning tunneling microscopy to elucidate the interplay between stoichiometry, morphology, chemical states, crystallization, magnetism, optical transparency, and electronic properties. Specifically, I studied the effect of annealing on the surface stoichiometry of the CoFeB/Cu system by in-situ AES and discovered that magnetic nanoparticles with controllable areal density can be produced. This is a good alternative for producing nanoparticles using a maskless process. Additionally, I studied the behavior of magnetic domain walls of the low coercivity alloy CoFeB patterned nanowires. MFM measurement with the in-plane magnetic field showed that, compared to their permalloy counterparts, CoFeB nanowires require a much smaller magnetization switching field , making them promising for low-power-consumption domain wall motion based devices. With oxides, I studied CuO nanoparticles on SnO2 based UV photodetectors (PDs), and discovered that they promote the responsivity by facilitating charge transfer with the formed nanoheterojunctions. I also demonstrated UV PDs with spectrally tunable photoresponse with the bandgap engineered ZnMgO. The bandgap of the alloyed ZnMgO thin films was tailored by varying the Mg contents and AES was demonstrated as a surface scientific approach to assess the alloying of ZnMgO. With gas sensors, I discovered the rf-sputtered anatase-TiO2 thin films for a selective and sensitive NO2 detection at room temperature, under UV illumination. The implementation of UV enhances the responsivity, response and recovery rate of the TiO2 sensor towards NO2 significantly. Evident from the high resolution XPS and AFM studies, the surface contamination and morphology of the thin films degrade the gas sensing response. I also demonstrated that surface additive metal nanoparticles on thin films can improve the response and the selectivity of oxide based sensors. I employed nanometer-scale scanning probe microscopy to study a novel gas senor scheme consisting of gallium nitride (GaN) nanowires with functionalizing oxides layer. The results suggested that AFM together with EFM is capable of discriminating low-conductive materials at the nanoscale, providing a nondestructive method to quantitatively relate sensing response to the surface morphology.

BRASIL: HACIA UN NUEVO BLOQUE HISTÓRICO

La coalición de fuerzas políticas que sostuvo el gobierno Fernando Henrique Cardoso durante cerca de ocho años entró definitivamente en crisis. El origen de esta crisis se encuentra en el agotamiento de una política económica que parecía exitosa en su comienzo pero que llevó de hecho el país a una de las más graves crisis de su historia.Esta fue la historia de las experiencias neoliberales de los años 90. Salinas duró seis años de esplendor, hasta la crisis del 94. Menen alcanzó reelegirse una vez pero no logró la segunda reelección hasta que su país entró en la dramática crisis actual. Fujimori también logró una reelección y cayó cuando quiso imponer su tercer mandato. En Venezuela la crisis explotó en el “Caracazo”, con Andrés Pérez en el gobierno, pero fue suplantada con más diez años de consenso neoliberal, que ganó la mayoría de la izquierda y pasó el bastión de la oposición al líder del intento insurreccional que se ligara al “Caracazo”: Hugo Chávez.

Trapping phenomena in AlGaN and InAlN barrier HEMTs with different geometries

PAPER Trapping phenomena in AlGaN and InAlN barrier HEMTs with different geometries S Martin-Horcajo1, A Wang1, A Bosca1, M F Romero1, M J Tadjer1,2, A D Koehler2, T J Anderson2 and F Calle1 Published 11 February 2015 • © 2015 IOP Publishing Ltd Semiconductor Science and Technology, Volume 30, Number 3 Article PDF Figures References Citations Metrics 350 Total downloads Cited by 1 articles Export citation and abstract BibTeX RIS Turn on MathJax Share this article Article information Abstract Trapping effects were evaluated by means of pulsed measurements under different quiescent biases for GaN/AlGaN/GaN and GaN/InAlN/GaN. It was found that devices with an AlGaN barrier underwent an increase in the on-resistance, and a drain current and transconductance reduction without measurable threshold voltage change, suggesting the location of the traps in the gate-drain access region. In contrast, devices with an InAlN barrier showed a transconductance and a decrease in drain associated with a significant positive shift of threshold voltage, indicating that the traps were likely located under the gate region; as well as an on-resistance degradation probably associated with the presence of surface traps in the gate-drain access region. Furthermore, measurements of drain current transients at different ambient temperatures revealed that the activation energy of electron traps was 0.43 eV and 0.38 eV for AlGaN and InAlN barrier devices, respectively. Experimental and simulation results demonstrated the influence of device geometry on the observed trapping effects, since devices with larger gate lengths and gate-to-drain distance values exhibited less noticeable charge trapping effects.

Una geografía del deseo en Los pobres de Roberto Sosa

Los pobres, por el autor hondureño Roberto Sosa, es un libro clave en la historia de la literatura centroamericana. Publicado en 1968, ganó el Premio Adonais y estableció a Roberto Sosa como uno de los poetas preeminentes de Centroamérica. Es un libro delgado de 21 poemas cuyo poder está tanto en lo que no dice como en lo que dice. Aunque sus temas de la pobreza, la opresión y el desamparo de las masas eran muy au courant por su tiempo, el evitar de la ideología estridente, del explícito historicismo acusador y del pensamiento estructuralista distingue a Sosa de sus contemporáneos centromericanos de la época como Ernesto Cardenal, Otto René Castillo y Roque Dalton. De hecho, embuye los poemas de una calidad que trasciende el tiempo y el espacio.

Impaired reverse cholesterol transport and hepatic steatosis contribute to pathogenesis of high fat dietinduced hyperlipidemia in murine models

Purpose: To investigate the pathogenesis of high fat diet (HFD)-induced hyperlipidemia (HLP) in mice, rats and hamsters and to comparatively evaluate their sensitivity to HFD. Methods: Mice, rats and hamsters were fed with high-fat diet formulation (HFD, n = 8) or a control diet (control, n = 8) for 4 weeks. Changes in body weight, relative liver weight, serum lipid profile, expressions of hepatic marker gene of lipid metabolism and liver morphology were observed in three hyperlipidemic models. Results: Elevated total cholesterol (TC), triglyceride, low density lipoprotein-cholesterol (LDL-C) and high density lipoprotein-cholesterol (HDL-C) levels and body weight were observed in all hyperlipidemic animals (p < 0.05), while hepatic steatosis was manifested in rat and hamster HLP models, and increased hepatic TC level was only seen (p < 0.05) in hamster HLP model. Suppression of HMG-CoA reductase and up-regulation of lipoproteinlipase were observed in all HFD groups. Hepatic gene expression of LDLR, CYP7A1, LCAT, SR-B1, and ApoA I, which are a response to reverse cholesterol transport (RCT), were inhibited by HFD in the three models. Among these models, simultaneous suppression of HMG-CR, LCAT, LDLR and SR-BI and elevated LPL were features of the hamster model. Conclusion: As the results show, impaired RCT and excessive fat accumulation are major contributors to pathogenesis of HFD-induced murine HLP. Thus, the hamster model is more appropriate for hyperlipidemia research.

Rapid identification and differentiation of Mycobacterium avium subspecies paratuberculosis types by use of real-time PCR and high-resolution melt analysis of the MAP1506 locus

High-resolution melt (HRM) analysis can identify sequence polymorphisms by comparing the melting curves of amplicons generated by real-time PCR amplification. We describe the application of this technique to identify Mycobacterium avium subspecies paratuberculosis types I, II, and III. The HRM approach was based on type-specific nucleotide sequences in MAP1506, a member of the PPE (proline-proline-glutamic acid) gene family.

Genetic and virulence-phenotype characterization of serotypes 2 and 9 of Streptococcus suis swine isolates

The aim of this study was to analyze the genetic characteristics and virulence phenotypes of Streptococcus suis, specifically, in clinical isolates of serotypes 2 and 9 (n = 195), obtained from diverse geographical areas across Spain. Pulsed-field gel electrophoresis (PFGE) typing identified 97 genetic profiles, 68% of which were represented by single isolates, indicative of a substantial genetic diversity among the S. suis isolates analyzed. Five PFGE profiles accounted for 33.3% of the isolates and were isolated from 38% of the herds in nine different provinces, indicative of the bacterium's widespread distribution in the Spanish swine population. Representative isolates of the most prevalent PFGE profiles of both serotypes were subjected to multilocus sequence typing (MLST) analysis. The results indicated that serotypes 2 and 9 have distinct genetic backgrounds. Serotype 2 isolates belong to the ST1 complex, a highly successful clone that has spread over most European countries. In accordance with isolates of this complex, most serotype 2 isolates also expressed the phenotype MRP(+)EF(+)SLY(+). Serotype 9 isolates belong to the ST61 complex, which is distantly related to the widespread European ST87 clone. Also, in contrast to most isolates of the European ST87 clone, which express the large variant MRP*, the majority of serotype 9 isolates (97.9%) did not express the protein.

Single nucleotide polymorphisms in the IS900 sequence of Mycobacterium avium subsp. paratuberculosis are strain type specific

Insertion sequence IS900 is used as a target for the identification of Mycobacterium avium subsp. paratuberculosis. Previous reports have revealed single nucleotide polymorphisms within IS900. This study, which analyzed the IS900 sequences of a panel of isolates representing M. avium subsp. paratuberculosis strain types I, II, and III, revealed conserved type-specific polymorphisms that could be utilized as a tool for diagnostic and epidemiological purposes.

The decrease of NAD(P)H:quinone oxidoreductase 1 activity and increase of ROS production by NADPH oxidases are early biomarkers in doxorubicin cardiotoxicity

info:eu-repo/semantics/publishedVersion

High Frequency Class DE Converter Using a Multilayer Coreless PCB Transformer

In modern power electronics equipment, it is desirable to design a low profile, high power density, and fast dynamic response converter. Increases in switching frequency reduce the size of the passive components such as transformers, inductors, and capacitors which results in compact size and less requirement for the energy storage. In addition, the fast dynamic response can be achieved by operating at high frequency. However, achieving high frequency operation while keeping the efficiency high, requires new advanced devices, higher performance magnetic components, and new circuit topology. These are required to absorb and utilize the parasitic components and also to mitigate the frequency dependent losses including switching loss, gating loss, and magnetic loss. Required performance improvements can be achieved through the use of Radio Frequency (RF) design techniques. To reduce switching losses, resonant converter topologies like resonant RF amplifiers (inverters) combined with a rectifier are the effective solution to maintain high efficiency at high switching frequencies through using the techniques such as device parasitic absorption, Zero Voltage Switching (ZVS), Zero Current Switching (ZCS), and a resonant gating. Gallium Nitride (GaN) device technologies are being broadly used in RF amplifiers due to their lower on- resistance and device capacitances compared with silicon (Si) devices. Therefore, this kind of semiconductor is well suited for high frequency power converters. The major problems involved with high frequency magnetics are skin and proximity effects, increased core and copper losses, unbalanced magnetic flux distribution generating localized hot spots, and reduced coupling coefficient. In order to eliminate the magnetic core losses which play a crucial role at higher operating frequencies, a coreless PCB transformer can be used. Compared to the conventional wire-wound transformer, a planar PCB transformer in which the windings are laid on the Printed Board Circuit (PCB) has a low profile structure, excellent thermal characteristics, and ease of manufacturing. Therefore, the work in this thesis demonstrates the design and analysis of an isolated low profile class DE resonant converter operating at 10 MHz switching frequency with a nominal output of 150 W. The power stage consists of a class DE inverter using GaN devices along with a sinusoidal gate drive circuit on the primary side and a class DE rectifier on the secondary side. For obtaining the stringent height converter, isolation is provided by a 10-layered coreless PCB transformer of 1:20 turn’s ratio. It is designed and optimized using 3D Finite Element Method (FEM) tools and radio frequency (RF) circuit design software. Simulation and experimental results are presented for a 10-layered coreless PCB transformer operating in 10 MHz.