Minimum of η/s\eta/s and the phase transition of the Linear Sigma Model in the large-N limit

We reexamine the possibility of employing the viscosity over entropy density ratio as a diagnostic tool to identify a phase transition in hadron physics to the strongly coupled quark-gluon plasma and other circumstances where direct measurement of the order parameter or the free energy may be difficult. It has been conjectured that the minimum of eta/s does indeed occur at the phase transition. We now make a careful assessment in a controled theoretical framework, the Linear Sigma Model at large-N, and indeed find that the minimum of eta/s occurs near the second order phase transition of the model due to the rapid variation of the order parameter (here the sigma vacuum expectation value) at a temperature slightly smaller than the critical one.Comment: 22 pages, 19 figures, v2, some references and several figures added, typos corrected and certain arguments clarified, revised for PR

Constraints on the initial mass, age and lifetime of Saturn's rings from viscous evolutions that include pollution and transport due to micrometeoroid bombardment

The Cassini spacecraft provided key measurements during its more than twelve year mission that constrain the absolute age of Saturn's rings. These include the extrinsic micrometeoroid flux at Saturn, the volume fraction of non-icy pollutants in the rings, and a measurement of the ring mass. These observations taken together limit the ring exposure age to be < a few 100 Myr if the flux was persistent over that time (Kempf et al., 2023). In addition, Cassini observations during the Grand Finale further indicate the rings are losing mass (Hsu et al., 2018; Waite et al., 2018) suggesting the rings are ephemeral as well. In a companion paper (Durisen and Estrada, 2023), we show that the effects of micrometeoroid bombardment and ballistic transport of their impact ejecta can account for these loss rates for reasonable parameter choices. In this paper, we conduct numerical simulations of an evolving ring in a systematic way in order to determine initial conditions that are consistent with these observations.Comment: 31 pages, 19 figures, 2 tables, Published in Icaru

Finanzas a Corto Plazo : Análisis del presupuesto de flujo de efectivo operativo de la empresa metalurgica de Nicaragua,S.A. para el año 2015

El presente trabajo de seminario de graduación titulado “Planificación Financiera” se desarrolló con el fin de proporcionar un entendimiento más claro sobre la elaboración de un presupuesto de efectivo y estados financieros proforma en la empresa Metalúrgica de Nicaragua S,A. El objetivo general planteado es realizar un presupuesto de efectivo y los estados financieros proforma del periodo 2015. Para dar cumplimiento al primer objetivo se expusieron los fundamentos de las finanzas, tales como el marco teórico, historia y evolución de las finanzas. Enmarcando su importancia en la toma de decisiones e interacción ante los fenómenos económicos externos. El segundo objetivo trata de los elementos de la planificación financiera tales como el estado de situación financiera, Estado de resultado integral, estado de flujo de efectivo y notas a los estados financieros además de información adicional proporcionada por el departamento de ventas y cobranzas de la empresa Metalúrgica de Nicaragua S,A. El tercer objetivo es evaluar las cifras obtenidas mediante la elaboración de un pronóstico de ingresos y gastos para conocer las necesidades de adquisición, los costos y la utilidad que se pueden obtener a través de los servicios; y con ello realizar una planificación del efectivo que permita el desarrollo de un Presupuesto de Caja, para lo cual se debe elaborar un programa de entradas de efectivo con el objeto de conocer los ingresos que obtendrá la empresa y un programa de salidas de efectivo para conocer los gastos que tendrá que efectuar en un período especifico, con los resultados obtenidos la empresa necesita de financiamiento externo requerido para poder apoyar el crecimiento de sus activos proyectados. El cuarto objetivo es el desarrollo del caso práctico de la empresa Metalúrgica de Nicaragua partiendo de los estados financieros 2013 y 2014 tomando en cuenta el comportamiento histórico de las operaciones de la empresa

Two infrared Yang-Mills solutions in stochastic quantization and in an effective action formalism

Three decades of work on the quantum field equations of pure Yang-Mills theory have distilled two families of solutions in Landau gauge. Both coincide for high (Euclidean) momentum with known perturbation theory, and both predict an infrared suppressed transverse gluon propagator, but whereas the solution known as "scaling" features an infrared power law for the gluon and ghost propagators, the "massive" solution rather describes the gluon as a vector boson that features a finite Debye screening mass. In this work we examine the gauge dependence of these solutions by adopting stochastic quantization. What we find, in four dimensions and in a rainbow approximation, is that stochastic quantization supports both solutions in Landau gauge but the scaling solution abruptly disappears when the parameter controlling the drift force is separated from zero (soft gauge-fixing), recovering only the perturbative propagators; the massive solution seems to survive the extension outside Landau gauge. These results are consistent with the scaling solution being related to the existence of a Gribov horizon, with the massive one being more general. We also examine the effective action in Faddeev-Popov quantization that generates the rainbow and we find, for a bare vertex approximation, that the the massive-type solutions minimise the quantum effective action.Comment: 13 pages, 7 figures. Change of title to reflect version accepted for publicatio

Diversidad genética de comunidades de hongos micorrízicos arbusculares (HMA) asociados a sistemas radiculares de café (Coffea arabica L.) y Sacha Inchi (Plukenetia volubilis L.) en la región San Martín

Universidad Nacional Agraria La Molina. Facultad de Ciencias. Departamento Académico de BiologíaLos hongos micorrícicos arbusculares (HMA) desempeñan un papel fundamental al facilitar la absorción de nutrientes y mejorar el crecimiento de las plantas a través de una simbiosis mutualista en sus raíces. En la región de San Martín, los cultivos de café y sacha inchi se benefician de esta simbiosis, sin embargo, la relación con respecto a esta composición es aún desconocida. En tanto, se plantearon los siguientes objetivos: a) Identificar los HMA a través del secuenciamiento masivo de ADN con Illumina, y b) Investigar la riqueza y composición de los HMA en relación a la geografía y la edad de las plantas. Para lo cual se realizaron muestreos de raíces en cinco localidades de la región de San Martin: Lamas, Bellavista, El Dorado y Picota para sacha inchi (parcelas de 1 año y 2 años); y Lamas, El Dorado y Moyobamba para café (parcelas de 1 año, entre 3 y 4 años, y mayores de 6 años). La caracterización molecular se realizó mediante una PCR anidada y el secuenciamiento fue con Illumina. Se determinaron cambios significativos en la diversidad alfa y beta del café en función de las edades del cultivo y las localidades. Probablemente la selección ambiental en el tiempo provocó limitaciones bióticas y abióticas que favorecieron a un conjunto de taxones de hongos HMA. No obstante, en el caso de la diversidad del sacha inchi solo se observó influencia de la geografía. Posiblemente el periodo de tiempo no fue lo bastante largo para mostrar variaciones, pero las alteraciones debido a las prácticas agrícolas sí tuvieron una relevancia significativa para este cultivo. Esto es un gran aporte para comprender la relación de la composición de HMA con estas plantas y las variables estudiadas, además de servir como base para el mejoramiento de café y sacha inchi.Arbuscular mycorrhizal fungi (AMF) play a crucial role in facilitating nutrient absorption and enhancing plant growth through a mutualistic symbiosis in their roots. In the San Martín region, coffee and sacha inchi crops benefit from this symbiosis, but the relationship regarding this composition remains unknown. Thus, the following objectives were proposed: a) Identify the AMF through DNA sequencing with Illumina, and b) Investigate the richness and composition of the AMF in relation to geography and plant age. For this, root samples were taken from five locations in the San Martín region: Lamas, Bellavista, El Dorado, and Picota for sacha inchi (plots of 1 year and 2 years); and Lamas, El Dorado, and Moyobamba for coffee (plots of 1 year, between 3 and 4 years, and older than 6 years). Molecular characterization was performed using nested PCR, and sequencing was done with Illumina. Significant changes were determined in the alpha and beta diversity of coffee based on age and locations. Likely because environmental selection over time caused biotic and abiotic constraints that favored a set of AMF taxa. However, for sacha inchi diversity, only geographic influence was observed. Perhaps the time period was not long enough to show variations, but alterations due to agricultural practices did have significant relevance for this crop. This is a significant contribution to understanding the relationship of AMF composition with these plants and the variables studied, and also serves as a basis for improving coffee and sacha inchi cultivation

Evaluación del turismo vivencial en la comunidad de Chahuaytire del año 2016.

La comunidad Chahuaytire, una tierra de grandes tejedores, se encuentra a 45 minutos del distrito de Pisaq, en la ciudad del cusco, donde se cultiva cientos de variedades de papas, está rodeado de cerros e ichu y bellos paisajes andinos, son pastores de llamas, alpacas y ovejas y con su fibra pueden realizar los tejidos más bellos en todo el departamento, tiene como sus atractivos principales las pinturas rupestres y la feria de textiles que se realizan todos los miércoles donde los tejedores salen a armar sus telares y comenzar su trabajo artesano. También se practica el turismo vivencial pero en la actualidad esta actividad no cuenta con mucha demanda turística pese a que cuenta con suficiente fuerza motivacional. El objetivo general para la elaboración del presente trabajo es evaluar la situación, en la que se encuentra el turismo vivencial en la comunidad de Chahuaytire del distrito de Pisaq. La metodología utilizada para la realización el presente trabajo de investigación es de tipo descriptivo, porque se describen los datos de la zona y evaluativa porque evaluara la situación actual del turismo vivencial de la comunidad de Chahuaytire. En las conclusiones se ha determinado la situación actual del turismo vivencial de la comunidad de Chahuaytire referido por los pobladores y turistas esta entre regular y bueno debido a que el lugar de estudio presenta características adecuadas para el desarrollo del producto turístico vivencial como es el caso de la textilería, sin embargo no cuenta con afluencia turística por falta de promoción y gestión del distrito de Pisaq y porque la mayoría de las casas de hospedaje su infraestructura no son la adecuada. Para ello se ha realizado algunas propuestas que nos pueda ayudar a mejorar la demanda como son: propuesta de concientización turística, capacitación al poblador involucrado en el turismo vivencial y la propuesta de promoción de la comunidad de Chahuaytire.The Chahuaytire community, a land of great weavers, is located forty-five minutes from the district of Pisaq, in the city of Cusco, where hundreds of varieties of potatoes are grown, surrounded by hills and ichu and beautiful Andean landscapes, they are shepherds of llamas, alpacas and sheep and with its fiber can make the most beautiful fabrics throughout the department, has as its main attractions the cave paintings and textile fair that take place every Wednesday where the weavers go out to assemble their looms and begin his artisan work. Experiential tourism is also practiced but nowadays this activity does not have much tourist demand despite having enough motivational forcé. The general objective for the elaboration of the present work is to evaluate the situation, in which is the existential tourism in the community of Chahuaytire of the district of Pisaq. The methodology used for the realization of this research work is descriptive, because the data of the zone and evaluative are described because it will evaluate the current situation of the existential tourism of the community of Chahuaytire. In the conclusions has been determined The current situation of the community tourism of Chahuaytire referred by the residents and tourists is between regular and good because the place of study presents adequate characteristics for the development of the experiential tourism product as is the case of the textile factory, however, does not have a tourist influx due to lack of promotion and management of the district of Pisaq and because most of the houses of lodging their infrastructure are not adequate, To this end, some proposals have been made that can help us improve demand, such as:tourism awareness proposal, training for the population involved in experiential tourism, and the proposal to promote the community of Chahuaytire.Tesi

Methodological issues in natural disaster loss normalization studies

The mixed results in Pielke (2020) for natural disaster loss normalisation studies are due to methodological differences. Flaws exist in commonly used normalisation approaches that assume unitary elasticities between exposure indicators and losses. We refute Pielke’s arguments that statistical studies estimating these relationships are biased. We conclude with an agenda for future research

U.S. Commission on Immigration Reform

The U.S. Commission on Immigration Reform was created by Congress to assess U.S. immigration policy and make recommendations regarding its implementation and effects. Mandated in the Immigration Act of 1990 to submit an interim report in 1994 and a final report in 1997, the Commission has undertaken public hearings, fact-finding missions, and expert consultations to identify the major immigration-related issues facing the United States today.LBJ School of Public Affair

Production and Characterization of Graphene and Other 2-Dimensional Nanomaterials: An AP High School Inquiry Lab (Curriculum Exchange)

According to the National Nanotechnology Initiative, nanoscience and nanotechnology are expected to play key roles in developing solutions to some of our greatest global engineering challenges in energy, medicine, security, and scientific discovery. There is high expectation that developments in nanotechnology will lead to new job creation and become an economic driver with new direction for research and development coming from nano-enabled products. In light of the potential economic and national security implications, it is imperative that we support the development of the next generation of the high school curriculum as a way to motivate students towards pursuing education and careers in nanotechnology. Recent advances in nanomaterials processing, particularly 2-dimensional nanomaterials synthesis, present the opportunity to integrate nanotechnology curriculum into high schools in safe and relatively inexpensive manners. The multifunctional characteristics of 2-dimensional nanomaterials make them attractive for printable and flexible electronics, nanostructured thermoelectrics, photovoltaics, batteries, and biological and chemical sensors. Thus, 2-dimensional nanomaterials provide anideal context for high school students to investigate the principles of nanoscience andnanotechnology. In our work, we present an Advanced Placement (AP) Chemistry Inquiry Laboratory (CIL),which is being implemented at Centennial High School in Meridian, Idaho. The CIL is aligned toNational College Board requirements for AP Chemistry courses as well as Next GenerationScience Standards. The laboratory is designed to encompass approximately five hours of time,including teacher preparation time, pre-laboratory activities, materials synthesis andcharacterization, and a field trip to a local industry partner for scanning electron microscopyanalysis of the resultant nanomaterials. Students are organized into small groups under thecontext that they are working to produce and characterize nanomaterials as part of an industryresearch team. To synthesis the 2-dimensional nanomaterials, students use cosolvent exfoliationof layered materials such as graphite, MoS2, WS2, and hBN. The students must then use opticalspectroscopy and electrical characterization techniques to determine if their material is aconductor, semiconductor, or an insulator. The students then use scanning electron microscopy to image the morphology of the 2-dimensional nanoflakes they produced, which exposes the students to advanced nanoscale characterization techniques