Towards gauge theories in four dimensions

The abundance of infrared singularities in gauge theories due to unresolved emission of massless particles (soft and collinear) represents the main difficulty in perturbative calculations. They are typically regularized in dimensional regularization, and their subtraction is usually achieved independently for virtual and real corrections. In this paper, we introduce a new method based on the loop-tree duality (LTD) theorem to accomplish the summation over degenerate infrared states directly at the integrand level such that the cancellation of the infrared divergences is achieved simultaneously, and apply it to reference examples as a proof of concept. Ultraviolet divergences, which are the consequence of the point-like nature of the theory, are also reinterpreted physically in this framework. The proposed method opens the intriguing possibility of carrying out purely four-dimensional implementations of higher-order perturbative calculations at next-to-leading order (NLO) and beyond free of soft and final-state collinear subtractions.Comment: Final version to appear in JHE

WOOD PROPERTIES OF NINE ACETYLATED TROPICAL HARDWOODS FROM FAST-GROWTH PLANTATIONS IN COSTA RICA

The treatment of acetylation on tropical woods is influenced by their different levels of permeability and how these affect the weight percentage gain (WPG) in acetylated wood. The objective of the current study was to identify the effect of acetylation on the thermal stability, color, physical properties, hygroscopic and dimensional stability, wetting rate, and durability of nine tropical species of woods used for the commercial reforestation in Costa Rica. Study results showed that WPG varied from 2.2% to 16.8%. Positive significant correlations were observed between WPG and pre-exponential factors in TGA analysis and two parameters of dimensional and hygroscopic stability, whereas a negative correlation was observed with water absorption. In species with a WPG of over 10% (Vochysia ferruginea, V. guatemalensis, Cordia alliodora, and Enterolobium cyclocarpum) the thermal stability, wetting rate, hygroscopic stability, and resistance to biological attack showed an increase while swelling, and water absorption decreased. For these species, the best behaviors were obtained with an acetylation time of 2.5 hours and WPG values of over 10%. The same properties of wood in species with a WPG under 5% were found to be less affected by the different acetylation times and showed little difference in relation to untreated wood. Finally, the analysis showed that the dimensional stability obtained was attributed to the reduction of the absorptive capacity of the acetylated wood

Non-centralized environment to monitor and dynamically con gure highly distributed systems

Estudi i desenvolupament d'una plataforma orientada a sistemes distribuïts per a l'avaluació del rendiment d'aplicacions que s'executen en aquests entorns de grans requeriments de transferència d'informació, com és el cas més clar en les aplicacions de gestió de placement

Diseño de un plan de mejora del proceso de producción de quesos para incrementar la productividad en la empresa de productos lácteos San Mateo S. R. L.

La presente investigación tiene como objetivo diseñar un plan de mejora del proceso de producción de quesos para incrementar la productividad en la empresa de productos lácteos San Mateo SRL., para el efecto se realiza un diagnóstico de la situación actual, se determina las metodologías adecuadas, se diseña el plan en base a las metodologías y herramientas seleccionadas; para finalmente, estimar el incremento de la productividad en base a la comparación de los indicadores actuales con una futura aplicación del plan de mejora. La investigación tuvo un enfoque cuantitativo y su alcance y diseño fue descriptico-propositivo, centrado en la eficiencia del proceso de fabricación. La población lo constituyen el proceso de producción. Para la recolección de datos se utiliza como técnicas el análisis documental, la entrevista y la encuesta y como instrumentos el cuestionario. Los principales resultados obtenidos demuestran que la producción actual es deficiente y el nivel de productividad de la empresa es bajo. En lo que se refiere a los resultados esperados, según las mejoras propuestas la eficiencia se incrementó en 31,5% y la eficacia en 35%. Asimismo, la productividad se incrementaría en 51,5%, la mano de obra en 2.94 Kg/h-H, la materia prima en 0.026 en Kg/litro y la productividad total en 0.342 soles. La conclusión más relevante es que para incrementar la productividad en la empresa de productos lácteos San Mateo SRL, se hace necesario aplicar un plan de mejora basado en metodologías y herramientas seleccionadas

Standardized Drought Indices for pre-summer drought assessment in tropical areas

The main climatic indices used for the determination of pre-summer drought severity were developed for temperate zones with very different climatic conditions from those found in the tropical climate zones, particularly with respect to seasonal rainfall variations. The temporal evolution of pre-summer drought leads the authors to compute the indices for each year over a defined period according to the climatic normals of each meteorological station and to consider the months inside the dry episode differently, according to the law of emptying the water reserves. As a function of this, standardized drought indices are proposed for the evaluation of the pre-summer drought in tropical zone. Two new indices were tested: one developed from precipitation and the other also considering temperature. These indices were validated by correlation with Advanced very-high-resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) time series and used to identify the most severe drought conditions in the Yucatan Peninsula. The comparison between the indices and their temporal variations highlighted the importance of temperature in the most critical events and left indications of the impact of global warming on the phenomenon.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones Geofísicas (CIGEFI)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencias del Mar y Limnología (CIMAR)UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Físic

Elimination of variability sources in NIR spectra for the determination of fat content in olive fruits

Models for prediction of oil content as percentage of dried weight in olive fruits were comput- ed through PLS regression on NIR spectra. Spectral preprocessing was carried out by apply- ing multiplicative signal correction (MSC), Sa vitzky–Golay algorithm, standard normal variate correction (SNV), and detrending (D) to NIR spectra. MSC was the preprocessing technique showing the best performance. Further reduction of variability was performed by applying the Wold method of orthogonal signal correction (OSC). The calibration model achieved a R 2 of 0.93, a SEPc of 1.42, and a RPD of 3.8. The R 2 obtained with the validation set remained 0.93, and the SEPc was 1.41

Recent developments from the loop-tree duality

In this talk, we review the most recent developments of the four-dimensional unsubstraction (FDU) and loop-tree duality (LTD) methods. In particular, we make emphasis on the advantages of the LTD formalism regarding asymptotic expansions of loop integrands.Comment: 8 pages, 1 figure. Presented at 13th International Symposium on Radiative Corrections RADCOR2017, 24-29 September 2017, St. Gilgen, Austri

System for recommending job titles based on user provided titles and categories

The present disclosure relates to a system and method of recommending job titles based on user-provided titles and categories. The system leverages an occupational ontology with multiple levels such as a job title, minor occupational category and major occupational category. The system receives job title or category as inputs from a user. It then classifies the job title or job category into one or more minor job categories. The system then uses a number of recommendation algorithms to generate several job titles. It then presents recommended job titles to the user in one final recommendation list. The user interface could either display all recommended job titles or a subset of job titles. In a variation of the method, the system could sense the user’s reactions to the recommended titles to improve recommendation algorithms over time