Listar Física por título
Mostrando ítems 84-103 de 114
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QA Programme of the TLD laboratory of the University of Costa Rica: IEC 61066 testing
(2008)The Thermoluminescence Personal Dosimetry Laboratory of the University of Costa Rica provides dose measurements for around 90% of occupational radiation workers in the country. The assessment of doses to workers routinely ... -
Quantum ferroelectric instabilities in superconducting SrTiO3
(2018)We examine the effects of strain and cation substitution on the superconducting phase of polar semiconductors near a ferroelectric quantum phase transition with a model that combines a strong coupling theory of ... -
Quantum Theory of Triboelectricity
(2020-10-30)We propose a microphysical theory of the triboelectric effect by which mechanical rubbing separates charges across the interface between two materials. Surface electrons are treated as an open system coupled to two baths, ... -
Random Electric Field Instabilities of Relaxor Ferroelectrics
(2017-06-13)Relaxor ferroelectrics are complex oxide materials which are rather unique to study the effects of compositional disorder on phase transitions. Here, we study the effects of quenched cubic random electric fields on the ... -
Relation between Luminescence and Electronic Surface Characteristics in p-type Porous Silicon
(1997)Measurements of photoluminescence, electronic surface states and effective surface area, at various stages of the anodization process, are presented. The results show a behavior different from that observed on n-type porous Si. -
Renormalización mejorada y multipolos armónicos
(2023)En este trabajo se proporciona una prueba de la estructura multipolar de los propagadores cinemáticos no regularizados de intensidades de campo de espín superior. Siguiendo el patrón identificado por primera vez en el ... -
Revealing a new region of gamma-ray emission in the vicinity of HESS J1825–137
(2019-02-17)HESS J1825–137 is a bright very high-energy gamma-ray source that has been firmly established as a pulsar wind nebula (PWN), and one of the most extended gamma-ray objects within this category. The progenitor supernova ... -
Search for gamma-ray emission from star-forming galaxies with Fermi LAT
(2016-08)Recent studies have found a positive correlation between the star-formation rate of galaxies and their gamma-ray luminosity. Galaxies with a high star-formation rate are expected to produce a large amount of high-energy ... -
Sesión "Medicina nuclear"
(2017-01)En la sesión dedicada a la Medicina Nuclear (MN) se identificaron los cinco aspectos que se consideran más problemáticos en la protección radiológica en MN. Estos hacen referencia a: 1. Garantizar que la dosis administrada ... -
Short term topological changes of coronal holes associated with prominence eruptions and subsequent CMEs
(2013-03-15)We study the short-term topological changes of equatorial and polar coronal hole (CH) boundaries, such as a variation of their area and disintegration, associated to reconnection with nearby (within 15° distance) quiescent ... -
Stochastic approach to the smart quantum confinement model in porous silicon
(Surface Science 515 (2002) L509-L513, 2002)A model that encompasses two approaches to explain the photoluminescence in p-type porous silicon is proposed. The model considers a stochastic distribution of nanocrystallite sizes within the porous matrix and explain the ... -
Structure factor of a relaxor ferroelectric
(2015-04-14)We study a minimal model for a relaxor ferroelectric including dipolar interactions, and short-range harmonic and anharmonic forces for the critical modes as in the theory of pure ferroelectrics together with quenched ... -
Study of oxide bands in p-type porous silicon layers
(2019)The interest in developing fast and reliable chemical and biochemical sensors in an inexpensive way is something that has attracted a lot of efforts in the last decades. One of the potential material candidates is ... -
The 2:3:6 quasi-periodic oscillation structure in GRS 1915+105 and cubic subharmonics in the context of relativistic discoseismology
(Monthly Notices of the Royal Astronomical Society 440:3011-3015, 2014-06-01)We propose a simple toy model to explain the 2:3:6 quasi-periodic oscillation (QPO) structure in GRS 1915+105 and, more generally, the 2:3 QPO structure in XTE J1550−564, GRO J1655−40 and H1743−322. The model exploits the ... -
The early rainy season in Central America: the role of thetropical North Atlantic SSTs
(2016)We explored the relationship between the precipitation anomalies during May to June as the first peak of the rainy season in the Pacific slope of Central America, and sea surface temperature (SST) fluctuations in the ... -
The gigaelectronvolt counterpart of ver j2019+407 in the northern shell of the supernova remnant g78.2+2.1 (γ cygni)
(2016-07)Analysis of gamma-ray emission from the supernova remnant G78.2+2.1 (γ Cygni) with 7.2 years of cumulative data from the Fermi Large Area Telescope shows a distinct hard, bright, and extended component to the north of the ... -
The High-Altitude water cherenkov (HAWC) observatory in México: The primary detector
(2023-07)The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the ... -
The Hubble Constant and the Deceleration Parameter in Anisotropic Cosmological Spaces of Petrov type D
(2016-11)In this paper the Hubble parameter and the deceleration parameter are analyzed for a group of anisotropic homogeneous solutions of the Petrov type-D. It is obtained that for the said set of solutions can be constructed a ...