8,946 research outputs found
Thermal transport in one-dimensional spin heterostructures
We study heat transport in a one-dimensional inhomogeneous quantum spin 1/2
system. It consists of a finite-size XX spin chain coupled at its ends to
semi-infinite XX and XY chains at different temperatures, which play the role
of heat and spin reservoirs. After using the Jordan-Wigner transformation we
map the original spin Hamiltonian into a fermionic Hamiltonian, which contains
normal and pairing terms. We find the expressions for the heat currents and
solve the problem with a non-equilibrium Green's function formalism. We analyze
the behavior of the heat currents as functions of the model parameters. When
finite magnetic fields are applied at the two reservoirs, the system exhibits
rectification effects in the heat flow.Comment: 10 pages, 5 figures, scheme of the system and comparison with
specific heat added. Accepted for publication in Phys. Rev.
Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy
In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an 241Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program
Modelo de processo de produção de micélio de Lentinula edodes em biomassa florestal para obtenção de embalagem biodegradável.
Editores técnicos: Marcílio José Thomazini, Elenice Fritzsons, Patrícia Raquel Silva, Guilherme Schnell e Schuhli, Denise Jeton Cardoso, Luziane Franciscon. EVINCI. Resumos
Estudo da obtenção de um biocompósito de biomassa de pupunha (Bactris gasipaes) e micélio de Lentinula edodes.
Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds
This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient‐restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica‐SUBNUT than in Pirenaica‐CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short‐term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long‐term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF‐1 and higher levels of cortisol.This work was supported by the Spanish Ministry of Economy and Business and the European Union Regional Development Funds (INIA RTA 2013‐00059‐C02 and INIA RZP 2015‐001) and the Government of Aragon under the Grant Research Group Funds (A14_17R). A. Noya received a PhD grant from INIA‐Government of Aragon
Deep eutectic solvents: green solvents for the removal of degraded gelatin on cellulose nitrate cinematographic films
Cellulose nitrate (CN) has been used in the past as support for photographic negatives and cinematographic films. This material is particularly unstable and can undergoes severe degradation due to thermal, photocatalytic and hydrolytic loss of nitro groups from the lateral chain. Thus, to prevent the disappearance of the movies, their scanning and digitalization become a priority. However, CN bases degradation may prevent the scanning of the films. The decrease in pH, for instance, lowers the viscosity of gelatin, which becomes softer. This causes the formation of gelatin residues which stick on the back of the superimposed frames inside the reels creating a deposit. Traditional approaches to clean gelatin residues from the surface of CN bases include the mechanical removal with scalpels and the use of organic solvents (such as isopropyl alcohol). However, these methods are either slow and ineffective or could potentially damage the degraded CN supports. To overcome these drawbacks, we have evaluated the performance of three choline chloride and betaine-based Deep Eutectic Solvent (DES) formulations as alternative for the removal of gelatine residues from CN supports. These solvents are inexpensive (when compared to traditional solvents), easy to prepare, green (non volatile, safe towards the operators and the environment, and potentially recyclable), non flammable and have been previously proposed for the extraction of proteinaceous materials, but their use for the restoration of photographic negatives or cinematographic films has not been reported yet. Selected areas over the frames of a real deteriorated CN cinematographic film were cleaned comparing the DES performances with the ones obtained using isopropyl alcohol as an example of a traditional method. In particular, the tested DES formulations showed superior cleaning power compared to isopropyl alcohol and, at the selected application times, resulted capable to remove the gelatin residues without affecting the CN film supports. Graphical abstract: [Figure not available: see fulltext.]
An Algebraic Criterion for the Ultraviolet Finiteness of Quantum Field Theories
An algebraic criterion for the vanishing of the beta function for
renormalizable quantum field theories is presented. Use is made of the descent
equations following from the Wess-Zumino consistency condition. In some cases,
these equations relate the fully quantized action to a local gauge invariant
polynomial. The vanishing of the anomalous dimension of this polynomial enables
us to establish a nonrenormalization theorem for the beta function ,
stating that if the one-loop order contribution vanishes, then will
vanish to all orders of perturbation theory. As a by-product, the special case
in which is only of one-loop order, without further corrections, is
also covered. The examples of the N=2,4 supersymmetric Yang-Mills theories are
worked out in detail.Comment: 1+32 pages, LaTeX2e, typos correcte
Glacis calcisolico y suelos con horizon cálcico en el NE de la provincia de Granada
[Resumen] La importancia del estudio de las zonas semiáridas parece incuestionable ya que constituyen uno de los ecosistemas más extensos del mundo. España en concreto es el país de Europa que tiene las zonas más extensas y además coinciden con los ambientes socialmente más deprimidos, cuyas características derivan de la aridez ambiental. En el sector nororiental de la provincia de Granada se localiza la Depresión de Baza, definida por un altiplano con una altitud media de 950 metros. La geomorfología queda dibujada por dos conjuntos: alineaciones montañosas y altiplanicie, dando ésta última un paisaje singular que por su extrema sequedad constituye uno de los paisajes más característicos de las zonas esteparias peninsulares. La desigual evolución de los suelos nos permite detallar en el presente trabajo la unidad edafogeomorfológica del glacis calcisólico, desarrollada por denudación de la superficie del glacis lúvico antiguo y la materialización de suelos con horizonte cálcico, originado antiguamente por precipitación del carbonato cálcico ante la desecación del suelo en la estación seca, o petrocálcico 9riginado tras repetidas redisoluciones y reprecipitaciones de la caliza, con fuerte cementación final.[Abstract] Semiarid zones are the vastest ecosystems in the world, therefore their study is very important. Spain is the european country supporting mostly european semiarid zones, moreover these areas are underdeveloped because of their arid environment. The Baza Depresion is located at the north-east of Granada province and is a high plateau with 950m altitude average. Geomorphology is composed for two formations: a mountainous area and a high plateau; this offers a singular landscape making up one of the most characteristics Spanish sttepe. In this study, the calcisolic glacis edaphogeomorphological unit is detailed. This unit is developed by denudation of the old luvic glacis and soils with calcic horizon; this horizon was originated by calcium carbonate precipitation during the dry season, or in the case of petrocalcic horizon, originated by repeated redisolutions and reprecipitations of the calcium carbonate
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