Evolution of quantum observables: from non-commutativity to commutativity

A fundamental aspect of the quantum-to-classical limit is the transition from a non- commutative algebra of observables to commutative one.However, this transition is not possible if we only consider unitary evolutions. One way to describe this transition is to consider the Gamow vectors, which introduce exponential decays in the evolution. In this paper, we give two mathematical models in which this transition happens in the infinite time limit. In the first one, we consider operators acting on the space of the Gamow vectors, which represent quantum resonances. In the second one, we use an algebraic formalism from scattering theory. We construct a non-commuting algebra which commutes in the infinite time limit.MINECO Grant MTM2014- 57129-C2-1-P. Junta de Castilla y Leon Grants BU229P18, VA137G18

Newtonian Flow in Converging-Diverging Capillaries

The one-dimensional Navier-Stokes equations are used to derive analytical expressions for the relation between pressure and volumetric flow rate in capillaries of five different converging-diverging axisymmetric geometries for Newtonian fluids. The results are compared to previously-derived expressions for the same geometries using the lubrication approximation. The results of the one-dimensional Navier-Stokes are identical to those obtained from the lubrication approximation within a non-dimensional numerical factor. The derived flow expressions have also been validated by comparison to numerical solutions obtained from discretization with numerical integration. Moreover, they have been certified by testing the convergence of solutions as the converging-diverging geometries approach the limiting straight geometry.Comment: 23 pages, 5 figures, 1 table. This is an extended and improved version. arXiv admin note: substantial text overlap with arXiv:1006.151

Numerical modeling of FSW welding process incorporating a parameter estimation technique

Los modelos numéricos de transferencia de calor y de flujo de fluido empleados en la simulación del proceso de soldadura por fricción-agitación (FSW) han contribuido a la comprensión del proceso. Sin embargo, existen ciertos parámetros de entrada a los modelos que no pueden determinarse fácilmente a partir de principios fundamentales o de las condiciones de soldadura. Como resultado, las predicciones de estos modelos no siempre están de acuerdo con los resultados experimentales. En este trabajo se usa el método de Levenberg-Marquardt (LM) para estimar de manera no lineal los parámetros desconocidos presentes en los modelos de transferencia de calor y de flujo de fluido, ajustando las temperaturas obtenidas con los modelos a mediciones experimentales de temperatura. Estos modelos se implementan en un programa de propósito general que emplea una formulación numérica desarrollada a partir del método de los elementos finitos (MEF). Los parámetros que se desconocen son: el coeficiente de fricción y la cantidad de adherencia del material a la superficie de la herramienta, el coeficiente de transferencia de calor en la superficie inferior y la cantidad de disipación viscosa convertida en calor. Los resultados obtenidos revelan una mejora de las predicciones de los modelos numéricos a partir de la incorporación de técnicas de estimación de parámetros.Numerical models of heat transfer and fluid flow used in the simulation of the friction-stir welding (FSW) process have contributed to the understanding of the process. However, there are some input model parameters that cannot be easily determined from fundamental principles or the welding conditions. As a result, the model predictions are not always in agreement with experimental results. In this work, the Levenberg-Marquardt (LM) method is used in order to perform a non-linear estimation of the unknown parameters present in the heat transfer and fluid flow models, by adjusting the temperatures results obtained with the models to temperature experimental measurements. These models are implemented in a general-purpose software that uses a numerical formulation developed from the finite element method (FEM). The unknown parameters are: the friction coefficient and the amount of adhesion of material to the surface of the tool, the heat transfer coefficient on the bottom surface and the amount of viscous dissipation converted into heat. The obtained results show an improvement in the numerical model predictions from the incorporation of parameter estimation techniques.Peer Reviewe

Adaptabilidad al cambio climático en especies forestales: efectos de la sequía sobre el crecimiento y la anatomía de la madera de pino ponderosa creciendo bajo distintos niveles de competencia

More stressful conditions are expected due to climatic change in several regions, including Patagonia, South-America. In this region, there are no studies about the impact of severe drought events on growth and wood characteristics of the most planted forestry species, Pinus ponderosa (Doug. ex-Laws). The objective of this study was to quantify the effect of a severe drought event on annual stem growth and functional wood anatomy of pines growing at different plantation densities aiming to understand how management practices can help to increase their adaptability to climate change. Growth magnitude and period, specific hydraulic conductivity, and anatomical traits (early- and latewood proportion, lumen diameter, cell-wall thickness, tracheid length and bordered pit dimensions) were measured in the ring 2008-2009, which was formed during drought conditions. This drought event decreased annual stem growth by 30-38% and 58-65% respect to previous mean growth, in open vs. closed stand trees, respectively, indicating a higher sensitivity of the latter, which is opposite to reports from the same species growing in managed native forests in USA. Some wood anatomical variables did differ in more water stressed trees (lower cell wall thickness of early wood cells and higher proportion of small-lumen cells in latewood), which in turn did not affect wood function (hydraulic conductivity and resistance to implosion). Other anatomical variables (tracheid length, pit dimensions, early- and latewood proportion, lumen diameter of early wood cells) did not differ between tree sizes and plantation density. The results suggest that severe drought affects differentially the amount but not the function and quality of formed wood in ponderosa pine growing at different competition levels.Los pronósticos de cambio climático indican condiciones de mayores niveles de estrés ambiental para muchas regiones del mundo, incluyendo la Patagonia, Sudamérica. En esta región no existen antecedentes acerca del impacto de eventos de sequía severa sobre el crecimiento y la anatomía funcional de la madera de Pinus ponderosa (Doug. ex-Laws), la especie forestal más plantada. El objetivo de este estudio fue cuantificar el efecto de un evento de este tipo sobre el crecimiento anual en diámetro y la anatomía de la madera de pinos creciendo a densidades de plantación bien diferenciadas, con la intención de entender cómo las prácticas de manejo pueden ayudar a incrementar la adaptabilidad al cambio climático. Se midieron las siguientes variables en el anillo de crecimiento 2008-2009: magnitud y período de crecimiento, conductividad hidráulica específica, proporción de madera temprana y tardía, y morfometría de los elementos de conducción: diámetro de lúmen, grosor de pared y longitud de traqueidas, y dimensiones de las punteaduras entre traqueidas. Este evento de sequía redujo la magnitud del crecimiento en un 30-38% y un 58-65% con respecto a los años previos en árboles creciendo en baja y alta competencia intraespecífica, respectivamente. Esto indica una mayor sensibilidad de los segundos, mientras se había encontrado una tendencia opuesta en bosques nativos de esta especie gestionados en EEUU. Se observaron diferencias en algunas variables anatómicas de los árboles más estresados (menor grosor de pared en traqueidas del leño temprano y células con lúmenes más pequeños en el leño tardío), que sin embargo no tuvieron un efecto en la función de la madera (conductividad hidráulica y resistencia a la implosión). Otras variables anatómicas no difirieron entre ambas densidades de plantación ni tamaño de árboles analizados (largo de traqueidas, dimensiones de punteaduras, proporción de madera temprana y tardía, diámetro de lúmenes de madera temprana). Los resultados sugieren que los eventos de sequía extrema afectan diferencialmente la cantidad pero no la función y calidad de la madera formada en pino ponderosa creciendo bajo distintos niveles de competencia

Avaliação e aplicação de métodos de genotipagem para estudo da síndrome da musculatura dupla em bovinos da raça Senepol.

Em várias raças de bovinos de corte é observada a síndrome da musculatura dupla, caracterizada pela presença do fenótipo de hipertrofia muscular, sendo esta uma condição hereditária e controlada pelo gene GDF-8 (Growth Differentiation Factor-8). Em bovinos da raça Senepol, a mutação nt821, localizada no exon III deste gene, é responsável por esta síndrome. Neste contexto, os objetivos deste trabalho foram avaliar três metodologias de genotipagem desta mutação, com o intuito de verificar qual a mais adequada em relação a custo/benefício e verificar a associação do alelo mutado com características de interesse econômico em touros jovens da raça Senepol. Foram extraídos DNA genômico de amostras biológicas de 17 bezerros, sendo sete com o fenótipo da musculatura dupla e dez sem o fenótipo. As amostras de DNA foram quantificadas por espectrofotometria e suas integridades avaliadas em gel de agarose 0,8%. Posteriormente, foram submetidas à reação em cadeia da polimerase (PCR) para amplificação do exon III. Foram testadas as metodologias: 1) sequenciamento direto do exon III do gene GDF-8; 2) detecção de fragmentos de DNA em gel de agarose a 4% e 3) detecção de fragmentos em sequenciador automático de DNA. Na primeira metodologia testada, foi possível detectar com precisão os genótipos de todos os indivíduos, entretanto, esta metodologia foi a mais onerosa. A técnica de detecção de fragmentos em gel de agarose a 4% resultou em 100% de concordância com os genótipos obtidos destes mesmos animais por sequenciamento. Porém, em toda corrida eletroforética é necessário acrescentar amostras de DNA controle de animais previamente genotipados, para garantir uma melhor visualização dos genótipos esperados, reduzindo, assim, artefatos técnicos. Esta metodologia foi a que apresentou o menor custo. Com o desenvolvimento de um sistema poolplexing, a detecção de fragmentos em sequenciador automático apesar de ser uma metodologia mais onerosa e laboriosa do que a técnica de detecção de fragmentos em gel de agarose apresenta a grande vantagem de poder ser realizada junto com os testes de paternidade de bovinos que são realizados rotineiramente pelos produtores, apresentando, assim, a melhor relação custo/benefício. Por meio do sistema poolplexing, foram genotipados 346 touros jovens Senepol, dos quais 70 animais (20,23%) apresentaram o genótipo heterozigoto (+/del) e 276 apresentaram o genótipo homozigoto (+/+), sem a presença da deleção nt821. Os touros Senepol heterozigotos apresentaram maior área de olho de lombo (AOL) e menor perímetro escrotal (PE), ambas as características ajustadas para 550 dias. Para os outros fenótipos avaliados não foram observadas diferenças estatísticas significativas (p<0,05). Alguns desses efeitos causados pela mutação nt821 podem ser considerados vantajosos do ponto de vista do produtor, como AOL enquanto que outros são desvantajosos, como foi para PE. Neste sentido, cabe ao produtor à decisão de manter ou não este alelo na população.Dissertação apresentada ao Programa de Pós-graduação em Zootecnia, área de concentração em Produção Animal no Cerrado-Pantanal, da Universidade Estadual de Mato Grosso do Sul, como parte das exigências para a obtenção do título de Mestre em Zootecnia.Orientador: Prof. Dr. André Luiz Julien Ferraz, UEMS; Co-orientadora: Dra. Fabiane Siqueira, Embrapa Gado de Corte

Two-Arm Flexible Thermal Strap

Airborne and space infrared cameras require highly flexible direct cooling of mechanically-sensitive focal planes. A thermal electric cooler is often used together with a thermal strap as a means to transport the thermal energy removed from the infrared detector. While effective, traditional thermal straps are only truly flexible in one direction. In this scenario, a cooling solution must be highly conductive, lightweight, able to operate within a vacuum, and highly flexible in all axes to accommodate adjustment of the focal plane while transmitting minimal force. A two-armed thermal strap using three end pieces and a twisted section offers enhanced elastic movement, significantly beyond the motion permitted by existing thermal straps. This design innovation allows for large elastic displacements in two planes and moderate elasticity in the third plane. By contrast, a more conventional strap of the same conductance offers less flexibility and asymmetrical elasticity. The two-arm configuration reduces the bending moment of inertia for a given conductance by creating the same cross-sectional area for thermal conduction, but with only half the thickness. This reduction in the thickness has a significant effect on the flexibility since there is a cubic relationship between the thickness and the rigidity or bending moment of inertia. The novelty of the technology lies in the mechanical design and manufacturing of the thermal strap. The enhanced flexibility will facilitate cooling of mechanically sensitive components (example: optical focal planes). This development is a significant contribution to the thermal cooling of optics. It is known to be especially important in the thermal control of optical focal planes due to their highly sensitive alignment requirements and mechanical sensitivity; however, many other applications exist including the cooling of gimbal-mounted components

Off-shell chromomagnetic dipole moments in the SM at and beyond the ZZ gauge boson mass scale

The off-shell anomalous chromomagnetic dipole moment of the standard model quarks ($u$, $d$, $s$, $c$ and $b$), at the $Z$ gauge boson mass scale, is computed by using the $\overline{\textrm{MS}}$ scheme. The numerical results disagree with all the previous predictions reported in the literature and show a discrepancy of up to two orders of magnitude in certain situations.Comment: 16 pages, 5 figure

Antioxidant and hypoglycemic effects of watercress (Nasturtium officinale) extracts in diabetic rats

Background: Watercress is a semi-aquatic plant used in traditional medicine to treat various ailments, such as flu, cough, avitaminosis, and anorexia; it is also used as a diuretic and for hypoglycemia treatment in diabetes. In this study, we report the antioxidant and hypoglycemic activity of orally administered aqueous (WAQE), acetonic (WAE), and alcoholic (WOHE) watercress extracts. The effect of subchronic administration of watercress extracts on oxidative stress was also studied.Materials and Methods: WAQE, WAE, and WOHE were obtained and administered orally. Alloxan (200 mg/kg) and streptozotocin (60 mg/kg) were applied to induce hyperglycemia in male Wistar rats. Phenolic and flavonoid content, as well as antioxidant activity of the extracts were measured. The acute and subchronic effects (8 weeks) of WAQE were evaluated. The activity of antioxidant enzymes levels of malondialdehyde, hepatic enzyme markers in the serum, and renal function markers, were assessed. Histopathological evaluation of the pancreas, kidney, and liver was performed using hematoxylin-eosin staining.Results: Watercress extracts have high concentrations of phenols, polyphenols, and flavonoids, in addition to a very high antioxidant effect. The hypoglycemic effect of WAQE upon acute administration was 76.6% higher than that of insulin. When administered chronically, glucose levels were normalized on the third week up to the eighth week. Furthermore, the antioxidant enzymes and biochemical parameters improved.Conclusion: WAQE administration to diabetic rats reduced oxidative stress damage and decreased glucose levels. This study supports the use of this plant for the treatment of diabetes.Keywords: Antioxidant, Diabetes, Watercress (Nasturtium officinale), Oxidative stress, Pancrea

Prevalence of infection with high-risk human papillomavirus in women in Colombia

AbstractThe prevalence of human papillomavirus (HPV) infections in 2109 females inhabiting five cities of Colombia was determined. Of the 49.2% with an HPV infection, 59.8% were infected with more than one viral type. Species 7 (of the the genus Alphapapillomavirus) was associated with multiple infections. Analysis of the socio-demographic data revealed a statistically significant protective effect associated with the status of civil union (civil recognition of cohabitation without marriage), and indigenous ethnicity proved to be a risk factor for HPV infection. This is the first study comparing HPV infection among women from geographical regions of Colombia with different socio-cultural structures

Burnout syndrome and its prevalence in primary care nursing: a systematic review and meta-analysis

Background: burnout syndrome is a significant problem in nursing professionals. Although, the unit where nurses work may influence burnout development. Nurses that work in primary care units may be at higher risk of burnout. The aim of the study was to estimate the prevalence of emotional exhaustion, depersonalization and low personal accomplishment in primary care nurses. Methods: We performed a meta-analysis. We searched Pubmed, CINAHL, Scopus, Scielo, Proquest, CUIDEN and LILACS databases up to September 2017 to identify cross-sectional studies assessing primary care nurses’ burnout with the Maslach Burnout Inventory were included. The search was done in September 2017. Results: After the search process, n = 8 studies were included in the meta-analysis, representing a total sample of n = 1110 primary care nurses. High emotional exhaustion prevalence was 28% (95% Confidence Interval = 22–34%), high depersonalization was 15% (95% Confidence Interval = 9–23%) and 31% (95% Confidence Interval = 6–66%) for low personal accomplishment. Conclusions: Problems such as emotional exhaustion and low personal accomplishment are very common among primary care nurses, while depersonalization is less prevalent. Primary care nurses are a burnout risk group.This work was funded by the Excellence Research Project P11HUM-7771 (Junta de Andalucía-Spain)