2,660 research outputs found
The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method
Using the formal analysis made by Bohm in his book, {\em "Quantum theory"},
Dover Publications Inc. New York (1979), to calculate approximately the phase
time for a transmitted and the reflected wave packets through a potential
barrier, we calculate the phase time for a semiconductor system formed by
different mesoscopic layers. The transmitted and the reflected wave packets are
analyzed and the applicability of this procedure, based on the stationary phase
of a wave packet, is considered in different conditions. For the applicability
of the stationary phase method an expression is obtained in the case of the
transmitted wave depending only on the derivatives of the phase, up to third
order. This condition indicates whether the parameters of the system allow to
define the wave packet by its leading term. The case of a multiple barrier
systems is shown as an illustration of the results. This formalism includes the
use of the Transfer Matrix to describe the central stratum, whether it is
formed by one layer (the single barrier case), or two barriers and an inner
well (the DBRT system), but one can assume that this stratum can be comprise of
any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph
Interference Simulator for the Whole HF Band: Application to CW-Morse
In this paper, we use jointly a model of narrow band interference and a
congestion model to model and implement an interference simulator for the whole
HF band. The result is a model to generate interfering signals that could be
found in a given frequency allocation, at a given time (past, present, or
future) and for a given location. Our model does not require measurements and
it is characterized by its ease of use and the freedom it offers to choose
scene (modulation, location, week, year, etc.). In addition, we have defined a
generic modulating function and the conditions to model a contact continuous
wave (CW)-Morse, which meets the usual standards of contest. Consequently, our
interference model in conjunction with the CW-Morse modulating function
designed results in a specific CW-Morse model for amateur contests. As an
example of the simulation model, we simulate the CW-Morse communications on the
contest ARR ARRL Field Day 2011.Comment: copyright 2023 IEEE. Personal use of this material is permitted.
Permission from IEEE must be obtained for all other uses, in any current or
future media, including reprinting/republishing this material for advertising
or promotional purposes, creating new collective works, for resale or
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this work in other work
Iberian Peninsula and Balearic Island Bathynellacea (Crustacea, Syncarida) database
This is the first published database of Bathynellacea. It includes all data of bathynellids (Crustacea, Bathynellacea) collected in the last 64 years (1949 to 2013) on the Iberian Peninsula and Balearic Island. Te samples come from groundwater (caves, springs, wells and hyporrheic habitat associated rivers) from both sampling campaigns and occasional sampling conducted throughout the Iberian Peninsula and Balearic Islands. Te dataset lists occurrence data of bathynellids distribution, sampling sites (with localities, county and geographic coordinates), taxonomic information (from family to species level) and sampling sources (collector and sampling dates) for all records. Te descriptions of new species and species identifications have been carried out by an expert taxonomist (AIC) with 25 years experience in the bathynellids studies (see references). Many of the sampling sites are type localities of endemic species from Iberian Peninsula. Te dataset includes 409 samples record corresponding to two families, 12 genera and 58 species, 42 of them formally described plus 16 taxa unpublished and 47 samples in study. All species known from the study area are included, which nearly sum up a quarter of species of Bathynellacea known in the world (250 species).This work was supported by project CGL2010-15786 MICINN
Detection of an ionized gas outflow in the extreme UV-luminous star-forming galaxy BOSS-EUVLG1 at z=2.47
BOSS-EUVLG1 is the most ultraviolet (UV) and Ly luminous galaxy
detected so far in the Universe, going through a very active starburst phase,
and forming stars at a rate (SFR) of 955 118 M yr. We
report the detection of a broad H component carrying 25% of the total
H flux. The broad H line traces a fast and massive ionized gas
outflow characterized by a total mass, of 7.94
0.15, an outflowing velocity (V) of 573 151 km s,
and an outflowing mass rate () of 44 20 M
yr. The presence of the outflow in BOSS-EUVLG1 is also supported by the
identification of blueshifted UV absorption lines in low and high ionization
states. The energy involved in the H outflow can be explained by the
ongoing star formation without the need for an Active Galactic Nucleus. The
derived low mass loading factor (= 0.05 0.03) indicates that
although massive, this phase of the outflow can not be relevant for the
quenching of the star formation. In addition, only a small fraction (
15%) of the ionized outflowing material with velocities above 372 km s
could escape the gravitational potential, and enrich the surrounding
circum-galactic medium at distances above tens of kpc. The ionized phase of the
outflow does not carry the mass and energy to play a relevant role neither in
the evolution of the host galaxy nor in the enrichment of the intergalactic
medium. Other phases of the outflow could be carrying most of the outflow
energy and mass in the form of hot X-ray emitting gas as predicted by some
recent simulations. The expected emission of the extended X-ray emitting halo
associated with the outflow in BOSS-EUVLG1 and similar galaxies could be
detected with the future X-ray observatory, {\it ATHENA} but could not be
resolved spatially.Comment: 8 pages, 3 figures, accepted in A&
Genetic differentiation between two geographic subpopulations of Bermeya goat
Ponencia publicada en ITEA, vol.104Este trabajo es un análisis preliminar de la diversidad y grado de diferenciación genética entre las subpoblaciones
Oriental y Occidental de la cabra de raza Bermeya de Asturias. Se han genotipado 27
microsatélites en 122 individuos pertenecientes a las poblaciones de cabra Bermeya Oriental, Bermeya
Occidental, del Guadarrama, Alpine y Saanen. Las poblaciones de raza Bermeya presentaron heterocigosis
esperadas menores de 0,6 y coascendencias moleculares dentro de población de 0,419, reflejando
una alta identidad genética entre individuos. Asimismo, el número medio de alelos por locus, ajustado
por el tamaño muestral, de las poblaciones Bermeya Oriental y Occidental fueron los menores
encontrados (3,8 y 3,9, respectivamente). La mayor coascendencia molecular se encontró entre las
poblaciones Bermeya Oriental-Guadarrama (0,388 ± 0,006), como consecuencia de la introgresión, en
el Oriente asturiano de individuos de tipo Pirenáico. Este parámetro entre las poblaciones de Bermeya
Oriental y Occidental fue de 0,371 ± 0,007. Puede ser necesario establecer estrategias de conservación
diferenciadas para las dos poblaciones geográficas de cabra Bermeya.Two geographic subpopulations (Eastern and Western) of the Asturian Bermeya goat were analysed
using 27 microsatellites. A total of 122 individuals of Bermeya, Guadarrama, Alpine and Saanen goat
breeds were genotyped. The Eastern and Western Bermeya subpopulations had expected
heterozygosity values lower than 0.6 and within-subpopulations molecular coancestry values of 0.419,
thus illustrating a high between individuals genetic identity. The rarefacted average number of alleles
per locus found in both the Eastern and the Western Bermeya subpopulations were the lowest in the
dataset (3.8 and 3.9, respectively). The higher between-populations molecular coancestry values was
found for the pair Eastern Bermeya-Guadarrama (0.388 ± 0.006), thus reflecting the introgression of
the Pyrenean-type goat into Eastern Asturias. This parameter between the two Bermeya
subpopulations was of 0.371 ± 0.007. It could be recommended the implementation of different
conservation strategies for each of the geographic subpopulations of Bermeya goat
Extrusión del componente plástico de la copa acetabular sin luxación protésica: a propósito de un caso
Se present a un caso de extrusión del component e plástic o (polietileno)
ocurrido en el transcurso del primer me s del postoperatorio en un pacient e que había
sufrido un recambio del component e acetabular. Se destaca el hecho de que cursase de
forma asintomática y de que no se acompañase de luxación de la prótesis.A case of disassembly of the polyethylene component of the acetabular
cup acurred in a patient one mouth after revision surgery for loosening of a screwed
acetabular cup is reported. Special emphasis is made in the asyntomati c clinic and on
the no association with dislocation of the femoral component
The extent to which genetics and lean grade affect fatty acid profiles and volatile compounds in organic pork
Niche production is intended to produce premium pork, but several husbandry factors may affect the meat fatty acid composition and aroma. Fatty acid profile (by GC-FID) of raw meat and volatile compounds (by SPME-GC-MS) of cooked meat were analysed in loin samples from two pig genetic types-75% Duroc (Du) and 50% Pietrain (Pi) rossbreds that were slaughtered at different weights (90 kg and 105 kg, respectively) to achieve similar target carcass fatness, and the outcome carcasses were balanced for lean grade groups (<60% or ≥60% lean) within genotypes. Genetic type did not affect fatty acids (FA) profile of meat. The leaner meat had lower C12:0 and C20:3n − 3, lower saturated fatty acids (SFA) and higher MUFA/SFA ratio content than the fattier meat. Short-chain alcohols were lower in Pietrain and in leaner pork compared to the samples from Duroc crossbreds and fattier pork. A greater amount of hexane,2,4,4-trimethyl (an aliphatic hydrocarbon) but lower carbon disulphide (sulphur compound) content was detected in pork from leaner compared to fattier pork. Higher aromatics hydrocarbons were exclusively associated with Duroc crossbreds, and lower aliphatic hydrocarbons with pigs classified as fattier. Most of the volatile compounds detected in the present study came from lipid oxidation.José Manuel Lorenzo is a member of the MARCARNE network, funded by CYTED (ref.116RT0503). The funders had no role in study design, data collection and analysis, decisionto publish, or preparation of the manuscript
Impact of the resistance responses to stress conditions encountered in food and food processing environments on the virulence and growth fitness of non-typhoidal salmonellae
The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Influence of the initial cell number on the growth fitness of salmonella enteritidis in raw and pasteurized liquid whole egg, egg white, and egg yolk
Salmonella growth in egg and egg products has been widely studied, but there are still some aspects that are not fully known. The objective of this work was to study the influence of the initial cell number on the growth fitness of Salmonella Enteritidis in raw and pasteurized egg products. Growth curves of five Salmonella Enteritidis strains in raw and pasteurized egg products, starting from different initial numbers, were obtained and fitted to the Baranyi and Roberts model. The results revealed that lower initial numbers led to longer lag phases (¿) and lower maximum specific growth rates (µmax) in raw liquid whole egg. Similar results were observed in raw egg white (except for one strain). Conversely, no influence (p > 0.05) of the initial concentration on Salmonella growth parameters in raw egg yolk was observed. On the other hand, no influence of the initial number of cells on Salmonella growth fitness in commercial pasteurized liquid whole egg was observed. The results obtained demonstrate that the disappearance of this initial-dose dependency phenomenon was dependent on the intensity of the thermal treatment applied. Finally, the influence of the initial number was, in general, lower in pasteurized than in raw egg white, but large differences among strains were observed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
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