A Review of Accelerated Test Models

Engineers in the manufacturing industries have used accelerated test (AT) experiments for many decades. The purpose of AT experiments is to acquire reliability information quickly. Test units of a material, component, subsystem or entire systems are subjected to higher-than-usual levels of one or more accelerating variables such as temperature or stress. Then the AT results are used to predict life of the units at use conditions. The extrapolation is typically justified (correctly or incorrectly) on the basis of physically motivated models or a combination of empirical model fitting with a sufficient amount of previous experience in testing similar units. The need to extrapolate in both time and the accelerating variables generally necessitates the use of fully parametric models. Statisticians have made important contributions in the development of appropriate stochastic models for AT data [typically a distribution for the response and regression relationships between the parameters of this distribution and the accelerating variable(s)], statistical methods for AT planning (choice of accelerating variable levels and allocation of available test units to those levels) and methods of estimation of suitable reliability metrics. This paper provides a review of many of the AT models that have been used successfully in this area.Comment: Published at http://dx.doi.org/10.1214/088342306000000321 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Potential Advantages of Conducting Short Duration Visits to the Martian Surface

Recent NASA concepts for human missions to Mars, including the Evolvable Mars Campaign and Design Reference Architecture 5.0, have focused on the conduct of missions with long duration stays on the Martian surface. The decision to focus on long duration missions (typically to a single site) is driven by a desire to increase the perceived sustainability of the human Mars campaign, predicated on the assumption that sustainability is best achieved by maximizing the level of activity on the surface, providing for continuous growth in operations, and promoting pioneering of Mars. However, executing a series of long duration missions to a single site is not the only option for human exploration of Mars that has been proposed. Other architectures have been evaluated that focus on missions with short duration surface stays, with each mission visiting a separate site on the surface. This type of architecture is less efficient in that elements are not typically reused from one mission to the next but requires a far less complex surface architecture. There are potentially valid arguments to be made that a short duration, multiple site approach could result in different types of advantages when compared to the long duration, single site approach to Mars exploration, particularly for initial human missions to Mars. These arguments revolve around four areas: Achieved Value, Risk Mitigation, Developmental Affordability, and Operational Affordability & Flexibility. The question of Achieved Value relates to the prioritization of goals for Martian exploration. As discussed, goals related to pioneering and expanding human presence are often referenced as justifications for the long duration approach. However, there are other competing goals, including science and exploration. While there is not a clear consensus among planetary scientists, many have argued that the value of being able to visit multiple sites could outweigh the value of continually visiting a single site. Risk Mitigation is a major concern for initial human missions to Mars. There are a number of hazards related to operating on the Martian surface that are not well characterized. It may be desirable to conduct a series of short duration missions to better understand the nature of these risks prior to committing to a long duration mission. Developmental Affordability relates to the ability of NASA and its partners to develop and deploy the proposed architecture. Any human missions to Mars will be among the most complex endeavors ever undertaken. The capabilities that must be developed to enable any human Mars missions are extremely challenging. The total design, development, test, and evaluation (DDT&E) budget required to develop just the essential capabilities alone will be substantial. If additional surface capabilities are required to support long duration surface stays, the development effort could be unaffordable. Operational Affordability & Flexibility relates to the continued costs to execute the Mars campaign. Long duration missions, even with some amount of in-situ resource utilization, require a significant level of resupply for every mission. This requires additional launches and in-space transportation assets, increasing the operational complexity and total operational cost. This paper will explore each of the four potential advantages of short duration missions in detail. The authors will present comparisons between proposed long duration and short duration architectures through an evaluation of relevant performance, cost, and risk metrics

Conocimientos actitudes y prácticas sobre Métodos anticonceptivos en los adolescentes que asisten a la Clínica de Planificación Familiar del Centro de Salud “Villa Libertad”, del Municipio de Managua, Departamento de Managua, en el periodo del 1° de Febrero al 31 de Mayo del 2013

Hasta hace pocos años la Salud Sexual y Reproductiva fue reconocida como parte integral del proceso de equilibrio de salud en el hombre, además la mayoría de los países en vía de desarrollo no contaban con verdaderos programas dirigidos de forma directa y objetiva en el abordaje de estas condiciones en los Adolescentes. Los embarazos en las adolescentes, aumento de infecciones de transmisión sexual, una creciente morbimortalidad perinatal en madres adolescentes y/o en mujeres que desarrollan abortos en condiciones deficientes de salud son un claro ejemplo de la magnitud del problema que en la actualidad enfrentan los sistemas de salud de los países pobres. Nicaragua es el país de América Latina con el porcentaje más alto porcentaje de embarazo en adolescentes con una alta tasa de muertes materna. El impacto socioeconómico que conllevan estos problemas, hace que el uso de los métodos anticonceptivos por parte de los adolescentes sea un tema de especial interés sobre todo porque este grupo poblacional son muy vulnerables debido a las condiciones socioeconómicas en que se desarrollan durante esta fase del ser humano. Además ellos representan la fuerza viva en el futuro de todos los países ya que representan los futuros profesionales, que son la fuerza productiva de nuestro país. La adolescencia es una etapa crítica en el desarrollo del ser humano pues hay mucha inseguridad e inmadurez y por otro lado un sentimiento de invencibilidad, un comportamiento normativo, con el fin de sentirse aceptados por los demás, factores que conllevan muchas veces a prácticas de riesgo. Debido a la importancia que reviste el tema se realizó un estudio en una muestra de 283 adolescentes que asisten a la Clínica de Planificación Familiar del Centro de Salud “Villa Libertad”, del Municipio de Managua, Departamento de Managua, aplicándose una encuesta dirigida a los adolescentes en estudio para valorar los conocimientos, actitudes y prácticas sobre el uso de métodos anticonceptivos. De los 283 estudiantes encuestados el 48.1% correspondió al grupo de 10 a 14 años y 51.9% al grupo de edad de 15 a 19 años. Respecto al sexo, el 62.9% correspondió al sexo femenino, y el 37.1% al masculino. En cuanto a la tendencia religiosa los adolescentes en estudio en 43.4% profesaban la religión católica y un 48.1% la evangélica. El 8.5% pertenecían a otras religiones. De manera general encontramos un buen nivel de conocimientos (85.8%) y actitudes favorables (86.5%) en los adolescentes pero prácticas incorrectas en la mayor parte de los adolescentes. Del total de todos los Adolescentes del estudio el 75.6% desarrollaron una mala práctica en relación a los Métodos Anticonceptivos. Lo que nos hace reflexionar en el papel que se está desempeñando en materia preventiva para que los adolescentes adopten prácticas sexuales seguras que disminuyan los riesgos de infecciones de transmisión sexual o embarazos no deseados. Cabe señalar que un buen nivel de conocimientos no conlleva a prácticas adecuadas pero si es importante a la hora de tomar decisiones. Los medios de comunicación masivos (Radio y Televisión) juegan un rol importante, ya que los adolescentes indicaron que la información obtenida sobre métodos anticonceptivos se originaba de diversas fuentes de manera simultánea. La edad más frecuente de IVSA fue de los 15 a 19 años (32.8%), pero solamente el 40% indico haber utilizado algún tipo de método anticonceptivo en su primera relación sexual. Siendo el más utilizado los preservativos y la del método de las píldoras anticonceptivas. Es con sus amigos principalmente con quienes los adolescentes hablan sobre este tema, no con los padres o maestros, cuando los principios y valores deben inculcarse en el seno del hogar. Es necesario que la población en general, maestros, padres de familia y adolescentes tomen conciencia de la magnitud del problema en nuestro país, ya que nos afecta a todos, repercutiendo en la calidad de vida, las oportunidades de desarrollo económico y causando severos daños en el seno de la familia

Estructura organizacional y estrategia empresarial

Diseñar organizaciones es el proceso mediante el cual se construye o cambia la estructura de una organización con la finalidad de lograr los objetivos previstos. La búsqueda bibliográfica revela la presencia de múltiples referentes conceptuales en torno a este tema. Dado que la teoría del diseño aborda las propiedades de las organizaciones y los aspectos del diseño, en este trabajo se revisa dicho marco conceptual para adoptar de ella los elementos necesarios para el diseño organizacional de empresas. Un elemento clave de esa arquitectura organizacional es que la organización no dependa de un solo apoyo, de un solo líder. Hay que asentar la organización en varias columnas de apoyoDesigning organizations is the process by which the structure of an organization is built or changed in order to achieve the objectives. The bibliographical research reveals the presence of multiple conceptual references on this topic. Given that design theory addresses the properties of organizations and aspects of design, this paper reviews the conceptual framework to adopt the necessary elements for the organizational design of companies. A key element of the organizational architecture is that the organization does not depend on a single person or leader, we must establish the organization in several support columns

Análisis financiero Conjunto Residencial Hacienda los Alcaparros etapa II

Trabajo de Síntesis AplicadaPara el Conjunto Residencial Hacienda los Alcaparros Etapa II, se inició con el análisis de los balances generales y estados de resultado de los dos últimos años utilizando el resultado de los siguientes indicadores financieros y determinando la estructura financiera. Para los años 2017 y 2018 se relacionaron las cuentas más representativas para medir el comportamiento que ha tenido en el transcurso de los años seleccionados. Se evidencia que el rubro de Deudores Copropietarios y Cuotas de Administración tienen la mayor participación en los activos donde la variación que se refleja de un año al otro es un incremento importante el cual representa 85,06% en deudores copropietarios y un 117,91% para cuotas de administración.INTRODUCCIÓN - PLANTEAMIENTO DEL PROBLEMA - OBJETIVOS - ESTADO DEL ARTE - METODOLOGÍA - DIAGNÓSTICO - RECOMENDACIONES - REFERENCIAS - ANEXOSEspecializaciónEspecialista en Análisis y Administración Financier

Disease progression in Plasmodium knowlesi malaria is linked to variation in invasion gene family members.

Emerging pathogens undermine initiatives to control the global health impact of infectious diseases. Zoonotic malaria is no exception. Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, has entered the human population. P. knowlesi, like Plasmodium falciparum, can reach high parasitaemia in human infections, and the World Health Organization guidelines for severe malaria list hyperparasitaemia among the measures of severe malaria in both infections. Not all patients with P. knowlesi infections develop hyperparasitaemia, and it is important to determine why. Between isolate variability in erythrocyte invasion, efficiency seems key. Here we investigate the idea that particular alleles of two P. knowlesi erythrocyte invasion genes, P. knowlesi normocyte binding protein Pknbpxa and Pknbpxb, influence parasitaemia and human disease progression. Pknbpxa and Pknbpxb reference DNA sequences were generated from five geographically and temporally distinct P. knowlesi patient isolates. Polymorphic regions of each gene (approximately 800 bp) were identified by haplotyping 147 patient isolates at each locus. Parasitaemia in the study cohort was associated with markers of disease severity including liver and renal dysfunction, haemoglobin, platelets and lactate, (r = ≥ 0.34, p =  <0.0001 for all). Seventy-five and 51 Pknbpxa and Pknbpxb haplotypes were resolved in 138 (94%) and 134 (92%) patient isolates respectively. The haplotypes formed twelve Pknbpxa and two Pknbpxb allelic groups. Patients infected with parasites with particular Pknbpxa and Pknbpxb alleles within the groups had significantly higher parasitaemia and other markers of disease severity. Our study strongly suggests that P. knowlesi invasion gene variants contribute to parasite virulence. We focused on two invasion genes, and we anticipate that additional virulent loci will be identified in pathogen genome-wide studies. The multiple sustained entries of this diverse pathogen into the human population must give cause for concern to malaria elimination strategists in the Southeast Asian region

A systems engineering analysis of energy economy options for the DDG-51 class of U.S. Naval ships

The SECNAV has identified an ambitious set of goals for the Navy's energy programs. The authors addressed DoN energy surety, economy, and ecology goals, scoped the problem to focus on the economy aspect of the DoN's energy goal, and further bounded the analysis to energy economy of the DDG-51 class of surface combatants which appeared to be an area with potentially high return on investment. The team determined that if energy was conserved or better utilized then the triad of SECNAV goals for energy surety, economy and ecology was positively addressed. This report documents a method to assess energy consumption that could be used to make trade-offs for current and future ships. Eight subsystems, along with fuel type, were researched for alternative solutions, with eight of nine subsystem alternatives resulting as "more cost effective." By implementing the optimal recommendations from our team findings and using the fully burdened cost of fuel, we estimate that the DDG-51 program could save $1 .9M per year per ship. For a fleet of 50 ships, this translates to a savings of$9 50M over ten years.http://archive.org/details/asystemsengineer109456950Approved for public release; distribution is unlimited

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure