104 research outputs found
Las masas actuales de Quercus petraea en Galicia
The presence and characterization of Quercus petraea in the northwest of the Iberian Peninsula have been slightly studied. Although Rivas (1987) restricts his filings to the Orocantábrica Province, subsequent studies have confirmed the presence of Quercus petraea out of this place. The present investigation was undertaken to study the placing and dasometry of that specie in Galicia (Spain). Twenty-two plots with Quercus petraea as dominant specie were studied. Data about placing characteristics (location, orography, fisiografia, vegetation...) and stand variables (diametrical measurements, height, and sticks extraction for analysing of ages and growths) were checked. Basic parameters of dasometric characterization were obtained in cabinet, and subsequently the statistic analysis of multiple variables was used to study and classify stands. With both studies, we can assure that it is possible to speak of two big groups of stands: one of them clearly has typical features of hybridisation with Quercus robur and Quercus pyrenaica, that are localized near Orocantábrica Province; and the other group, that does not present those hybridisation features, is localized in the more oriental mountains. Finally, this classification in confirmed with other results as weight parameters, age, growth, etc. Consequently, the more pure stands produce data of greater maturity and a clear relation between their distribution and the classic idea of their preference by shady exhibitions is not observed in this area.La presencia y caracterización de Quercus petraea en el noroeste de la Península Ibérica han sido poco estudiadas. Aunque Rivas (1987) limita a la Provincia Orocantábrica sus manifestaciones, trabajos posteriores han constatado la presencia de dicha especie fuera de esa zona. Se presenta a continuación información acerca de la localización y dasometría de la especie dentro de la zona en la que está presente en Galicia. Los datos analizados corresponden a un total de 22 parcelas de muestreo pobladas con Quercus petraea como especie dominante. En ellas se han tomado datos sobre características de la estación (localización, orografía, fisiografía, vegetación...) y de la masa (mediciones diametrales, de altura y extracción de bastones para análisis de edades y crecimientos). En gabinete se obtienen parámetros de caracterización dasométrica básicos, para luego realizar un análisis estadístico de variables múltiples para el estudio y clasificación de las masas. Combinando ambos estudios nos permiten asegurar que se puede hablar de dos grandes bloques de masas: las que claramente manifiestan rasgos de hibridación con Quercus robur o con Quercus pyrenaica, que se sitúan en los límites de la Provincia Orocantábrica; y las que no, siendo estas últimas las de las montañas más orientales. Finalmente, esta misma división se ratifica con otros resultados, como son los parámetros de masa, edad, crecimiento, etc. Consecuentemente, las masas más puras arrojan datos de mayor madurez y no se observa en esta área una relación clara entre su distribución y la clásica idea de su preferencia por exposiciones de umbría
Salmonella in free-living exotic and native turtles and in pet exotic turtles from SW Spain
We screened 78 native and 94 exotic turtles from natural ponds and 39 exotic pet turtles for presence of Salmonella, resulting with infection rates of 6.61%, 6.4%, and 5.1%, respectively. Concurrent shedding of multiple serotypes of the bacteria was only detected in one pet turtle. Eleven isolates were obtained in free-living turtles, including serotypes commonly found in reptiles and also the serotype Typhimurium, which is commonly related to human infections. In pet turtles, the five serotypes isolated were different to those isolated in free-living turtles and had been reported to cause reptile-associated salmonellosis in humans. These results confirm the risk of transmission of Salmonella from free-living and pet turtles to humans, demanding the necessity of regulation of pet turtle trade in Europe. © 2008 Elsevier Ltd. All rights reserved.Peer Reviewe
Inverse Low Gain Avalanche Detectors (iLGADs) for precise tracking and timing applications
Low Gain Avalanche Detector (LGAD) is the baseline sensing technology of the
recently proposed Minimum Ionizing Particle (MIP) end-cap timing detectors
(MTD) at the Atlas and CMS experiments. The current MTD sensor is designed as a
multi-pad matrix detector delivering a poor position resolution, due to the
relatively large pad area, around 1 ; and a good timing resolution,
around 20-30 ps. Besides, in his current technological incarnation, the timing
resolution of the MTD LGAD sensors is severely degraded once the MIP particle
hits the inter-pad region since the signal amplification is missing for this
region. This limitation is named as the LGAD fill-factor problem. To overcome
the fill factor problem and the poor position resolution of the MTD LGAD
sensors, a p-in-p LGAD (iLGAD) was introduced. Contrary to the conventional
LGAD, the iLGAD has a non-segmented deep p-well (the multiplication layer).
Therefore, iLGADs should ideally present a constant gain value over all the
sensitive region of the device without gain drops between the signal collecting
electrodes; in other words, iLGADs should have a 100 fill-factor by
design. In this paper, tracking and timing performance of the first iLGAD
prototypes is presented.Comment: Conference Proceedings of VCI2019, 15th Vienna Conference of
Instrumentation, February 18-22, 2019, Vienna, Austri
Helminth communities of the exotic introduced turtle, Trachemys scripta elegans in southwestern Spain: Transmission from native turtles
We report the prevalence and diversity of helminth parasites found in native turtles Mauremys leprosa and Emys orbicularis from three localities in southwestern Spain and we describe the helminth communities of exotic turtles Trachemys scripta elegans coexisting in the wild with both native turtle species. Five nematodes species were identified, of which Serpinema microcephalus was the only species common between two localities, although infection parameters were different between them. This is the first report of cross transmission of S. microcephalus and Falcaustra donanaensis from native to exotic turtles and the first report of genus Physaloptera in turtles of the Palearctic Region. Continuous releasing of exotic pet turtles in wildlife ecosystems increases the risk of parasite introductions and, consequently, potential transmission to native species, and highlights the impending need for regulation of pet turtle trade in Europe
Metal Abundances of KISS Galaxies. I. Coarse Metal Abundances and the Metallicity-Luminosity Relation
We derive metal abundance estimates for a large sample of starbursting
emission-line galaxies (ELGs). Our sample is drawn from the KPNO International
Spectroscopic Survey (KISS) which has discovered over 2000 ELG candidates to
date. Follow-up optical spectra have been obtained for ~900 of these objects. A
three step process is used to obtain metal abundances for these galaxies. We
first calculate accurate nebular abundances for 12 galaxies whose spectra cover
the full optical region from [OII]3726,29 to beyond [SII]6717,31 and include
detection of [OIII]4363. Using secondary metallicity indicators R_23 and p_3,
we calculate metallicities for an additional 59 galaxies with spectra that
cover a similar wavelength range but lack [OIII]4363. The results are used to
calibrate relations between metallicity and two readily observed emission-line
ratios, which allow us to estimate coarse metallicities for 519 galaxies in
total. The uncertainty in these latter abundance estimates is 0.16 dex. From
the large, homogeneously observed sample of star-forming galaxies we identify
low metallicity candidates for future study and investigate the
metallicity-luminosity relation. We find a linear metallicity-luminosity
relation of the following form: 12 + log(O/H) = 4.059 - 0.240 M_B, with an RMS
scatter of 0.252. This result implies that the slope of the metallicity-
luminosity relation is steeper than when dwarf galaxies are considered alone,
and may be evidence that the relationship is not linear over the full
luminosity range of the sample.Comment: 15 pages, including 7 figures and 4 tables. To appear in May, 2002 A
Galactic Evolution along the Hubble Sequence
A generalization of the multiphase chemical evolution model applied to a wide
set of theoretical galaxies is shown. This set of models has been computed by
using the so-called Universal Rotation Curve from Persic, Salucci & Steel to
calculate the radial mass distributions of each theoretical galaxy. By assuming
that the molecular cloud and star formation efficiencies depend on the
morphological type of each galaxy, we construct a bi-parametric grid of models
whose results are valid in principle for any spiral galaxy, of given maximum
rotation velocity or total mass, and morphological type.Comment: Proceedings of the Euroconference "The Evolution of Galaxies. III..."
(Kiel 2002
Assessing the sensitivity of data-limited methods for resources in the Atlantic waters
ICES Annual Science Conference 2021, online 6-10 SeptemberLength-based methods have been widely applied to estimate biological parameters and to under-stand the dynamics of marine resource populations within the category of data-limited stocksThe authors thank the financial support of the project IMPRESS (RTI2018-099868-B-I00) project, ERDF, Ministry of Science, Innovation and Universities - State Research Agency, and also of GAIN (Xunta de Galicia), GRC MERVEX (nº IN607-A 2018-4)N
Applying length-based assessment methods to fisheries resources of the Bay of Biscay and Atlantic Iberian Waters: stock status and parameters sensitivity
ASLO 2021 Aquatic Sciences Virtual Meeting, 22–27 June 2021Length-based methods have been widely applied to estimate biological parameters and to understand the dynamics of marine resource populations within the category of data-limited stocksProject IMPRESS (RTI2018-099868-B-I00), ERDF, Ministry of Science, Innovation and Universities - State Research Agency, and also of GAIN (Xunta de Galicia), GRC MERVEX (nº IN607-A 2018-4)N
Oxygen and Nitrogen in Isolated Dwarf Irregular Galaxies
We present long slit optical spectroscopy of 67 HII regions in 21 dwarf
irregular galaxies to investigate the enrichment of oxygen, nitrogen, neon,
sulfur, and argon in low mass galaxies. Oxygen abundances are obtained via
direct detection of the temperature sensitive emission lines for 25 HII
regions; for the remainder of the sample, oxygen abundances are estimated from
strong line calibrations. The direct abundance determinations are compared to
the strong-line abundance calibrations of both McGaugh (1991) and Pilyugin
(2000). Global oxygen and nitrogen abundances for this sample of dwarf
irregular galaxies are examined in the context of open and closed box chemical
evolution models. While several galaxies are consistent with closed box
chemical evolution, the majority of this sample have an effective yield ~1/4 of
the expected yield for a constant star formation rate and Salpeter IMF,
indicating that either outflow of enriched gas or inflow of pristine gas has
occurred. The effective yield strongly correlates with M_H/L_B in the sense
that gas-rich galaxies are more likely to be closed systems. However, the
effective yield does not appear to correlate with other global parameters such
as dynamical mass, absolute magnitude, star formation rate or surface
brightness. A correlation is found between the observed nitrogen-to-oxygen
ratio and the color of the underlying stellar population; redder dwarf
irregular galaxies have higher N/O ratios than blue dwarf irregular galaxies.
The relative abundance ratios are interpreted in the context of delayed release
of nitrogen and varied star formation histories.Comment: 47 pages, 11 figures. Accepted to Ap
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