Una fórmula práctica para el coeficiente de impacto en puentes de ferrocarril

El artículo presenta un resumen de la situación actual en cuanto a la determinación de coeficientes de impacto en puentes. Los numerosos ensayos realizados en el seno de la Unión Internacional de Ferrocarriles por medio de su oficina de investigación (O.R.E.)han permitido relacionar los estudios teóricos con los resultados experimentales y establecer para el impacto una fórmula universal que no depende del material ni tipo estructural, y sí solamente de las características dinámicas del puente.

Realización de un procedimiento para la medida del coeficiente de absorción sonora normal

El objetivo de este trabajo es la elaboración de un procedimiento para la medida del coeficiente de absorción sonora normal en un tubo de impedancia. Para ello se han estudiado los fundamentos básicos de la ecuación de ondas y sus soluciones. Se han considerado las soluciones pertinentes que describen el comportamiento de una onda sonora dentro de un tubo rígido. Se ha considerado también la teoría básica de funciones de transferencia. Estas teorías son claves a la hora de poder desarrollar el procedimiento de medida, ya que el coeficiente de absorción acústica se obtendrá con la ayuda de un tubo de impedancias que mide las funciones de transferencia entre dos posiciones de micrófonos incorporados en una de las caras del tubo. La utilización de esta técnica tiene como principal ventaja, la necesidad de poco espacio en un laboratorio y el empleo de muestras pequeñas de material. La implementación de los visto teóricamente a su aplicación práctica se ha hecho a través de un procedimiento de medida que sigue la Norma UNE-EN ISO 10534-2 (2002) “Determinación del coeficiente de absorción sonoro y la impedancia en tubos de impedancia Parte 2: método función de transferencia”. El valor del coeficiente de absorción se puede obtener a través de una instrumentación específica y un programa computador. Para poder validar los cálculos que realiza el programa utilizado, se ha realizado una batería de medidas del coeficiente de absorción a diferentes tipos de materiales acústicos, y los cálculos se han hecho por la vía del programa y por la vía de una hoja de cálculo. Como parte del procedimiento de medida se ha calculado la incertidumbre en las medidas. En definitiva se pretende contribuir con este trabajo a establecer un procedimiento de medida del comportamiento acústico de diversos materiales. SUMMARY. The aim of this work is the development of a procedure for measuring the sound absorption coefficient normal of an impedance tube. To this end we have studied the basics of the wave equation and its solutions. We have considered the relevant solutions that describe the behavior of a sound wave in a rigid tube. It has also considered the basic theory of transfer functions. These theories are key when we want to develop the measurement method, since the absorption coefficient is obtained with the aid of an impedance tube measuring transfer functions between two positions of microphones incorporated into one side of the tube. The use of this technique has the main advantage, the need of little space on a laboratory and use of small samples of material. The implementation of theoretically seen to his practical application has been made through a measurement procedure following the UNE-EN ISO 10534-2 (2002) "Determination of sound absorption coefficient and impedance in impedance tubes Part 2 : transfer function method ". The value of the absorption coefficient can be obtained through a specific instrumentation and computer software. In order to validate the calculations performed by the program used, there has been realized a series of measures of the absorption coefficient at different types of acoustical materials, and calculations were made by means of the program and by means of a spreadsheet. As part of the measurement procedure has been estimated uncertainty in the measurements. Ultimately it’s tried to contribute with this work to establish a procedure measuring the acoustic behavior of various materials.

Dispositivos basados en el efecto Hall. Parte I

Se presenta aquí un elemento pasivo, de reciente desarrollo, el generador Hall. Este elemento de pequeñísimo tamaño, se basa en un efecto descubierto en 1789 por Hall. En primer lugar, se estudia el efecto, que tiene lugar en los metales, en los semiconductores e incluso en los gases ionizados. El coeficiente de Hall Rh o bien la sensitividad K0 representan en cierto modo la, capacidad de funcionamiento del generador, y por esto resulta muy interesante profundizar un poco en ello y ver qué factores influyen sobre los valores de aquellos parámetros. Se citan algunas de las muchas propiedades de aplicación del elemento. Para terminar esta primera parte, dedicada al efecto en los semiconductores, presentamos un circuito equivalente, cuyo margen de validez vendrá en cada caso determinado por los valores máximos establecidos por el fabricante. Por último, se expone el principio del multiplicador, y sobre un multiplicador comercial se tratan de explicar algunos resultados del mismo que parecen pobres, dada la posibilidad teórica de la cápsula en sí. Aunque comprendemos que gran parte de los inconvenientes provienen de los mismos circuitos, como no conocemos éstos,nos ceñimos más bien a los errores que provienen de la propia cápsula. Parece más honrado y quizás añada algo de luz sobre el conocimiento del elemento considerado

Estudio de la precisión en la determinación del coeficiente de absorción acústica en tubo de impedancia

El objetivo del presente Trabajo Fin de Máster es estudiar la precisión de los resultados obtenidos en la medición del coeficiente de absorción acústica en tubo de impedancia, según la norma UNE-EN ISO 10534-2 “Determinación del coeficiente de absorción acústica y de la impedancia acústica en tubos de impedancia. Parte 2: Método de la función de transferencia”. En primer lugar, se han estudiado los fundamentos teóricos relacionados con el método de ensayo. A continuación, se ha detallado dicho método y se ha aplicado a un caso práctico con la instrumentación disponible en el laboratorio de Acústica de la Escuela. En relación a la precisión del método se ha analizado si la preparación e instalación de la muestra son causas de imprecisión. Para ello, se han realizado varios ensayos con dos tipos de materiales acústicos, con el fin de estudiar la dispersión entre los resultados que produce tanto el corte de la muestra, realizado en el proceso de confección, como su colocación en el tubo de impedancia. Además, se ha estudiado si desviaciones en la medida de la temperatura y de la distancia entre los micrófonos influyen en los valores del coeficiente de absorción acústica medido y de su incertidumbre asociada. Puesto que el resultado de un ensayo únicamente se halla completo cuando está acompañado de una declaración acerca de la incertidumbre de dicho resultado, en el presente trabajo se ha aplicado a este método de ensayo un procedimiento para estimar la incertidumbre empleando el método de Monte Carlo. ABSTRACT The objective of this project is studying the precision of the measurements of sound absorption coefficient in impedance tube, according to standard UNE-EN ISO 10534-2 “Determination of sound absorption coefficient and impedance in impedance tubes. Part 2: Transfer-function method”. Firstly, theoretical basis related to the test method have been studied. Furthermore, this method has been defined and applied to a particular case with the instrumentation available in the Acoustics laboratory of the College. In relation to the precision of the method, the preparation and installation of the test sample have been analyzed as possible causes of imprecision. For this purpose, two types of acoustic materials have been tested in order to study the deviation between the results produced by the cutting of the test sample and the collocation in impedance tube. In addition, it has been studied if deviations in the measurement of the temperature and distance between microphones may influence the sound absorption coefficient measured and its associated uncertainty. The test result must be accompanied by a statement of the uncertainty of the result. For this reason, in this project a procedure for estimating uncertainty of the result of this test method has been applied using the Monte Carlo method.

Análisis de las causas de dispersión en los resultados de las medidas del coeficiente de absorción acústica en cámara reverberante

El objetivo del presente Trabajo Fin de Máster es llevar a cabo un estudio de las causas de la precisión de los resultados de las medidas del coeficiente de absorción acústica en cámara reverberante, siguiendo el procedimiento descrito en la norma UNE-EN ISO 354 “Medición de la absorción acústica en una cámara reverberante”. En primer lugar, se han estudiado los fundamentos teóricos relacionados con el método de ensayo. A continuación, se ha detallado dicho método y se ha aplicado a un caso práctico con la instrumentación disponible en el laboratorio de Acústica de la Escuela. Puesto que el resultado de un ensayo únicamente se halla completo cuando está acompañado de una declaración acerca de la incertidumbre de dicho resultado, en el presente trabajo se ha aplicado a este método de ensayo, tanto el enfoque clásico de la GUM, como el método de Monte Carlo, para evaluar la incertidumbre y comparar los resultados obtenidos mediante las dos metodologías. Para estudiar la influencia que produce en el campo sonoro de una cámara reverberante la introducción de un material absorbente en su interior, se realizó un estudio mediante trazado de rayos de la cámara reverberante del CEIS. ABSTRACT The objective of this Master's Thesis is to study the causes of accuracy of the measurements results of sound absorption coefficient in a reverberation room, according to the procedure of standard UNE-EN ISO 354 "Measurement of sound absorption in a reverberation room ". Firstly, theoretical basis related to the test method have been studied. Then, this method has been defined and applied to a particular case with the instrumentation available in the Acoustics laboratory of the College. The test result must be accompanied by a statement of the uncertainty of the result. For this reason, Monte Carlo method and GUM uncertainty framework have been applied in this project for estimating uncertainty and comparing the results obtained by these two methodologies. In addition, a study was made in the reverberation room of CEIS, by ray tracing, to study the influence on the sound field produced by the introduction of an absorbent material inside of the room.

Forças, momentos e coeficiente de atrito em teste de três pontos e em teste de resistência ao deslizamento com braquetes autoligáveis e fios 0.014\" utilizando um novo dispositivo

O objetivo principal do estudo é comparar o teste em 3 pontos com braquetes com o teste de resistência ao deslizamento utilizando um novo dispositivo que realiza a mensuração simultânea do coeficiente de atrito, das forças e dos momentos nos braquetes de ancoragem e da força de desativação no braquete desalinhado, exercidos por fios ortodônticos. Os objetivos secundários foram desenvolver o dispositivo e comparar, no teste em 3 pontos: (i) a influência, nas grandezas e no coeficiente de atrito cinético, da variação da simetria nas distâncias inter-braquetes, do tipo de braquete de ancoragem (canino ou 2º pré-molar), do deslocamento (3 ou 5mm) do braquete central, do sentido do desalinhamento (vestibular ou lingual) do braquete central e da marca de fio-braquete; (ii) as 3 formas de cálculo do coeficiente de atrito cinético; (iii) os 10 ciclos, para vestibular ou lingual, para verificar se eles são semelhantes ou não entre si. Foram utilizados braquetes autoligáveis (dentes 13, 14 e 15) e fios 0.014\'\' NiTi e CuNiTi das marcas Aditek e Ormco. O teste de resistência ao deslizamento foi realizado no desalinhamento lingual, nos dois deslocamentos e na configuração simétrica. O teste em 3 pontos com braquetes foi realizado no desalinhamento lingual e vestibular, nos dois deslocamentos e na configuração simétrica e assimétrica. Por meio da ANOVA, foram comparados, entre os dois tipos de teste: (A) as grandezas e o coeficiente de atrito e (B) o coeficiente de atrito gerado apenas no braquete de 2º pré-molar. Utilizando-se do mesmo teste estatístico foram comparados, no teste em 3 pontos com braquetes: (A) na configuração simétrica, algumas grandezas e o coeficiente de atrito advindos da variação da marca de fio-braquete, do deslocamento, do desalinhamento e do tipo de braquete; (B) algumas grandezas e o coeficiente de atrito gerados na configuração simétrica e assimétrica; (C) os valores das 3 formas de cálculo do coeficiente de atrito na configuração simétrica; e (D) algumas grandezas e o coeficiente de atrito encontrados nos 10 ciclos. Resultados: (A) a maioria dos valores das grandezas e do coeficiente de atrito gerados pelos dois tipos de teste foram diferentes estatisticamente; (B) o braquete de 2º pré-molar apresentou valores de coeficiente de atrito diferentes entre os dois tipos de teste; (C) na configuração simétrica, as variáveis foram estatisticamente significantes na maioria dos casos para as grandezas analisadas e para o coeficiente de atrito; (D) houve diferença entre a configuração simétrica e assimétrica; (E) o coeficiente de atrito baseado nas duas normais e na força de atrito se aproximou mais da realidade clínica e foi sensível à variação da geometria da relação fio-braquete; e (F) os 10 ciclos para lingual foram semelhantes entre si em 70% dos casos e os 10 ciclos para vestibular foram diferentes em 57% dos casos. Conclusões: o teste em 3 pontos com braquetes é diferente do teste de resistência ao deslizamento; a variação das configurações geométricas e da marca de fio-braquete pode influenciar nos valores das grandezas e do coeficiente de atrito cinético; os 10 ciclos para lingual foram mais semelhantes entre si que os 10 ciclos para vestibular.

An Isoflavone From Dipteryx Alata Vogel Is Active Against The In Vitro Neuromuscular Paralysis Of Bothrops Jararacussu Snake Venom And Bothropstoxin I, And Prevents Venom-induced Myonecrosis.

Snakebite is a neglected disease and serious health problem in Brazil, with most bites being caused by snakes of the genus Bothrops. Although serum therapy is the primary treatment for systemic envenomation, it is generally ineffective in neutralizing the local effects of these venoms. In this work, we examined the ability of 7,8,3'-trihydroxy-4'-methoxyisoflavone (TM), an isoflavone from Dipteryx alata, to neutralize the neurotoxicity (in mouse phrenic nerve-diaphragm preparations) and myotoxicity (assessed by light microscopy) of Bothrops jararacussu snake venom in vitro. The toxicity of TM was assessed using the Salmonella microsome assay (Ames test). Incubation with TM alone (200 μg/mL) did not alter the muscle twitch tension whereas incubation with venom (40 μg/mL) caused irreversible paralysis. Preincubation of TM (200 μg/mL) with venom attenuated the venom-induced neuromuscular blockade by 84% ± 5% (mean ± SEM; n = 4). The neuromuscular blockade caused by bothropstoxin-I (BthTX-I), the major myotoxic PLA2 of this venom, was also attenuated by TM. Histological analysis of diaphragm muscle incubated with TM showed that most fibers were preserved (only 9.2% ± 1.7% were damaged; n = 4) compared to venom alone (50.3% ± 5.4% of fibers damaged; n = 3), and preincubation of TM with venom significantly attenuated the venom-induced damage (only 17% ± 3.4% of fibers damaged; n = 3; p < 0.05 compared to venom alone). TM showed no mutagenicity in the Ames test using Salmonella strains TA98 and TA97a with (+S9) and without (-S9) metabolic activation. These findings indicate that TM is a potentially useful compound for antagonizing the neuromuscular effects (neurotoxicity and myotoxicity) of B. jararacussu venom.

Nebivolol Reduces Central Blood Pressure In Stage I Hypertensive Patients: Experimental Single Cohort Study.

Assessment of central blood pressure (BP) has grown substantially over recent years because evidence has shown that central BP is more relevant to cardiovascular outcomes than peripheral BP. Thus, different classes of antihypertensive drugs have different effects on central BP despite similar reductions in brachial BP. The aim of this study was to investigate the effect of nebivolol, a β-blocker with vasodilator properties, on the biochemical and hemodynamic parameters of hypertensive patients. Experimental single cohort study conducted in the outpatient clinic of a university hospital. Twenty-six patients were recruited. All of them underwent biochemical and hemodynamic evaluation (BP, heart rate (HR), central BP and augmentation index) before and after 3 months of using nebivolol. 88.5% of the patients were male; their mean age was 49.7 ± 9.3 years and most of them were overweight (29.6 ± 3.1 kg/m2) with large abdominal waist (102.1 ± 7.2 cm). There were significant decreases in peripheral systolic BP (P = 0.0020), diastolic BP (P = 0.0049), HR (P < 0.0001) and central BP (129.9 ± 12.3 versus 122.3 ± 10.3 mmHg; P = 0.0083) after treatment, in comparison with the baseline values. There was no statistical difference in the augmentation index or in the biochemical parameters, from before to after the treatment. Nebivolol use seems to be associated with significant reduction of central BP in stage I hypertensive patients, in addition to reductions in brachial systolic and diastolic BP.

Predictive Value Of Phase I Trials For Safety In Later Trials And Final Approved Dose: Analysis Of 61 Approved Cancer Drugs.

Phase I trials use a small number of patients to define a maximum tolerated dose (MTD) and the safety of new agents. We compared data from phase I and registration trials to determine whether early trials predicted later safety and final dose. We searched the U.S. Food and Drug Administration (FDA) website for drugs approved in nonpediatric cancers (January 1990-October 2012). The recommended phase II dose (R2PD) and toxicities from phase I were compared with doses and safety in later trials. In 62 of 85 (73%) matched trials, the dose from the later trial was within 20% of the RP2D. In a multivariable analysis, phase I trials of targeted agents were less predictive of the final approved dose (OR, 0.2 for adopting ± 20% of the RP2D for targeted vs. other classes; P = 0.025). Of the 530 clinically relevant toxicities in later trials, 70% (n = 374) were described in phase I. A significant relationship (P = 0.0032) between increasing the number of patients in phase I (up to 60) and the ability to describe future clinically relevant toxicities was observed. Among 28,505 patients in later trials, the death rate that was related to drug was 1.41%. In conclusion, dosing based on phase I trials was associated with a low toxicity-related death rate in later trials. The ability to predict relevant toxicities correlates with the number of patients on the initial phase I trial. The final dose approved was within 20% of the RP2D in 73% of assessed trials.

Pyrimidine-5'-nucleotidase Campinas, A New Mutation (p.r56g) In The Nt5c3 Gene Associated With Pyrimidine-5'-nucleotidase Type I Deficiency And Influence Of Gilbert's Syndrome On Clinical Expression.

Pyrimidine-5'-nucleotidase type I (P5'NI) deficiency is an autosomal recessive condition that causes nonspherocytic hemolytic anemia, characterized by marked basophilic stippling and pyrimidine nucleotide accumulation in erythrocytes. We herein present two African descendant patients, father and daughter, with P5'N deficiency, both born from first cousins. Investigation of the promoter polymorphism of the uridine diphospho glucuronosyl transferase 1A (UGT1A) gene revealed that the father was homozygous for the allele (TA7) and the daughter heterozygous (TA6/TA7). P5'NI gene (NT5C3) gene sequencing revealed a further change in homozygosity at amino acid position 56 (p.R56G), located in a highly conserved region. Both patients developed gallstones; however the father, who had undergone surgery for the removal of stones, had extremely severe intrahepatic cholestasis and, liver biopsy revealed fibrosis and siderosis grade III, leading us to believe that the homozygosity of the UGT1A polymorphism was responsible for the more severe clinical features in the father. Moreover, our results show how the clinical expression of hemolytic anemia is influenced by epistatic factors and we describe a new mutation in the P5'N gene associated with enzyme deficiency, iron overload, and severe gallstone formation. To our knowledge, this is the first description of P5'N deficiency in South Americans.

Effects Of Partial Inhibition Of Respiratory Complex I On H2o 2 Production By Isolated Brain Mitochondria In Different Respiratory States.

The aim of this work was to characterize the effects of partial inhibition of respiratory complex I by rotenone on H2O2 production by isolated rat brain mitochondria in different respiratory states. Flow cytometric analysis of membrane potential in isolated mitochondria indicated that rotenone leads to uniform respiratory inhibition when added to a suspension of mitochondria. When mitochondria were incubated in the presence of a low concentration of rotenone (10 nm) and NADH-linked substrates, oxygen consumption was reduced from 45.9 ± 1.0 to 26.4 ± 2.6 nmol O2 mg(-1) min(-1) and from 7.8 ± 0.3 to 6.3 ± 0.3 nmol O2 mg(-1) min(-1) in respiratory states 3 (ADP-stimulated respiration) and 4 (resting respiration), respectively. Under these conditions, mitochondrial H2O2 production was stimulated from 12.2 ± 1.1 to 21.0 ± 1.2 pmol H2O2 mg(-1) min(-1) and 56.5 ± 4.7 to 95.0 ± 11.1 pmol H2O2 mg(-1) min(-1) in respiratory states 3 and 4, respectively. Similar results were observed when comparing mitochondrial preparations enriched with synaptic or nonsynaptic mitochondria or when 1-methyl-4-phenylpyridinium ion (MPP(+)) was used as a respiratory complex I inhibitor. Rotenone-stimulated H2O2 production in respiratory states 3 and 4 was associated with a high reduction state of endogenous nicotinamide nucleotides. In succinate-supported mitochondrial respiration, where most of the mitochondrial H2O2 production relies on electron backflow from complex II to complex I, low rotenone concentrations inhibited H2O2 production. Rotenone had no effect on mitochondrial elimination of micromolar concentrations of H2O2. The present results support the conclusion that partial complex I inhibition may result in mitochondrial energy crisis and oxidative stress, the former being predominant under oxidative phosphorylation and the latter under resting respiration conditions.

National Institutes Of Health Consensus Development Project On Criteria For Clinical Trials In Chronic Graft-versus-host Disease: I. The 2014 Diagnosis And Staging Working Group Report.

The 2005 National Institutes of Health (NIH) Consensus Conference proposed new criteria for diagnosing and scoring the severity of chronic graft-versus-host disease (GVHD). The 2014 NIH consensus maintains the framework of the prior consensus with further refinement based on new evidence. Revisions have been made to address areas of controversy or confusion, such as the overlap chronic GVHD subcategory and the distinction between active disease and past tissue damage. Diagnostic criteria for involvement of mouth, eyes, genitalia, and lungs have been revised. Categories of chronic GVHD should be defined in ways that indicate prognosis, guide treatment, and define eligibility for clinical trials. Revisions have been made to focus attention on the causes of organ-specific abnormalities. Attribution of organ-specific abnormalities to chronic GVHD has been addressed. This paradigm shift provides greater specificity and more accurately measures the global burden of disease attributed to GVHD, and it will facilitate biomarker association studies.

Oropouche Virus Infection And Pathogenesis Is Restricted By Mavs, Irf-3, Irf-7, And Type I Ifn Signaling Pathways In Non-myeloid Cells.

Oropouche virus (OROV) is a member of the Orthobunyavirus genus in the Bunyaviridae family and a prominent cause of insect-transmitted viral disease in Central and South America. Despite its clinical relevance, little is known about OROV pathogenesis. To define the host defense pathways that control OROV infection and disease, we evaluated OROV pathogenesis and immune responses in primary cells and mice that were deficient in the RIG-I-like receptor signaling pathway (MDA5, RIG-I, or MAVS), downstream regulatory transcription factors (IRF-3 or IRF-7), IFN-β, or the receptor for type I IFN signaling (IFNAR). OROV replicated to higher levels in primary fibroblasts and dendritic cells lacking MAVS signaling, the transcription factors IRF-3 and IRF-7, or IFNAR. In mice, deletion of IFNAR, MAVS, or IRF-3 and IRF-7 resulted in uncontrolled OROV replication, hypercytokinemia, extensive liver damage, and death whereas wild-type (WT) congenic animals failed to develop disease. Unexpectedly, mice with a selective deletion of IFNAR on myeloid cells (CD11c Cre(+) Ifnar(f/f) or LysM Cre(+) Ifnar(f/f)) did not sustain enhanced disease with OROV or La Crosse virus, a closely related encephalitic orthobunyavirus. In bone marrow chimera studies, recipient irradiated Ifnar(-/-) mice reconstituted with WT hematopoietic cells sustained high levels of OROV replication and liver damage, whereas WT mice reconstituted with Ifnar(-/-) bone marrow were resistant to disease. Collectively, these results establish a dominant protective role for MAVS, IRF-3 and IRF-7, and IFNAR in restricting OROV virus infection and tissue injury, and suggest that IFN signaling in non-myeloid cells contributes to the host defense against orthobunyaviruses. Oropouche virus (OROV) is an emerging arthropod-transmitted orthobunyavirus that causes episodic outbreaks of a debilitating febrile illness in humans in countries of South and Central America. The continued expansion of the range and number of its arthropod vectors increases the likelihood that OROV will spread into new regions. At present, the pathogenesis of OROV in humans or other vertebrate animals remains poorly understood. To define cellular mechanisms of control of OROV infection, we performed infection studies in a series of primary cells and mice that were deficient in key innate immune genes involved in pathogen recognition and control. Our results establish that a MAVS-dependent type I IFN signaling pathway has a dominant role in restricting OROV infection and pathogenesis in vivo.