2,808 research outputs found
Validating GIC modeling in the Spanish power grid by differential magnetometry
series of experiences and recommendations are presented concerning the derivation of geomagnetically induced currents (GIC) by use of the differential magnetometry method (DMM) under power lines. This indirect technique, intended to obtain observations to validate GIC models, is an alternative to measuring the current flow in the transformer neutrals. It is a non-intrusive and autonomous technique, as the procedure does not depend on the grid operator. In contrast, the selection of suitable sites devoid of human interferences, the need for power to supply the magnetometer, the data acquisition and transmission system, along with the choice of the appropriate instrumentation are difficulties that make not just any site suitable for installation and often require costly solutions. We focus on the methodology followed to estimate the GIC flowing in several transmission lines of the Spanish power grid with the aim of validating our GIC models, and we share our experience on the installation of the measuring points. Uncertainty inherent in the DMM is assessed, showing that noise is the main handicap, although it can be minimized with appropriate filtering. According to such experience, on some occasions only total DC currents above a significant fraction of 1 A give magnetic signatures well above the noise level, so this figure can roughly be considered as the threshold limit for detection. The low solar activity, combined with the mid-latitude condition of Spain, limited the significance of available recorded data, but we can already report and analyze the results for several minor geomagnetic storms
Probing the near infrared stellar population of Seyfert galaxies
We employ IRTF SpeX NIR (0.8-2.4 microns) spectra to investigate the stellar
population (SP), active galactic nuclei (AGN) featureless continuum (FC) and
hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the starlight code and
the hot dust as an additional base element were used for the first time in this
spectral range. We found evidence of correlation among the equivalent widths
(W) Si I 1.59 microns x Mg I 1.58 microns, equally for both kinds of activity.
Part of the W{Na I 2.21 microns} and W {CO 2.3 microns} strengths may be
related to galaxy inclination. Our synthesis shows significant differences
between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the
K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2;
about 50 % of the Sy 2 galaxies require a component contribution >20%,
while this fraction increases to 60% in the Sy 1; also, in about 50 % of the
Sy2, the combined FC and young components contribute with more than 20%, while
this occurs in 90% of the Sy1, suggesting recent star formation in the central
region. The central few hundred parsecs of our galaxy sample contain a
substantial fraction of intermediate-age SPs with a mean metallicity near
solar. Our SP synthesis confirms that the 1.1 micron CN band can be used as a
tracer of intermediate-age SPs. The simultaneous fitting of SP, FC and hot dust
components increased in ~150% the number of AGNs with hot dust detected and the
mass estimated. The NIR emerges as an excellent window to study the stellar
population of Sy 1 galaxies, as opposed to the usually heavily attenuated
optical range. Our approach opens a new way to investigate and quantify the
individual contribution of the three most important NIR continuum components
observed in AGNs.Comment: The paper contains 14 figures and 5 tables. Accepted for publication
in MNRA
Prótesis total de cadera con doble recubrimiento de porometal e hidroxiapatita: resultados preliminares
El objetivo de este trabajo es evaluar la eficacia de la prótesis con superficie de
Poropatita, recubrimiento doble de Poropros e Hidroxiapatita, para su fijación ósea directa en
el reemplazo total de cadera. El estudio ha sido llevado a cabo en 80 pacientes con un seguimiento
mínimo de 3 años. La valoración clínica se ha realizado según el sistema de Harris modificado,
obteniendo un 90% de buenos resultados y un 10% de resultados regulares en la
serie estudiada. El análisis, revisado a partir de parámetros clínicos y radiográficos, permite
apreciar que el recubrimiento de un metal poroso con hidroxiapatita supone un mecanismo de
seguridad en la fijación primaria como secundaria del implante. La estabilidad inmediata del
componente femoral y cotiloideo, factor importante en la osteointegración del implante.This study was aimed at evaluating the outcome in terms of primary bone fixation
of a total hip prosthesis coated with Poropatita®
, o double coating of porous-metal and hidroxyapatite.
The study reviews 80 patients operated on with a minimum follow-up of 3 years.
A modified Harris score was used for clinical assessment. Good clinical results wer obtained in
9 0% of patients, while 10% achieved a fair outcome. Based on clinical and radiographic parameters,
porous-metal and hidroxyapatite double coating provides both excellent primary and
secondary bone fixation of the prosthetic components. Primary stability of both femoral stem
and cup seens to be an important factor for osteointegration of the implant
La artroscopia de rodilla: experiencia de 474 casos
El objetivo de este trabajo es dar a conocer los resultados de un estudio de 474
artroscopias realizadas en nuestro Servicio de Cirugía Ortopédica y Traumatología desde el
mes de enero 1988 hasta agosto 1992. La edad media de los pacientes fue de 32 años, con
una mayor incidencia en el sexo masculino (73%). La patología más frecuente correspondió a
la meniscopatía interna (48%). Tuvimos una estancia media hospitalaria de 3 días, apreciándose
una relación inversa entre ésta y la edad del paciente. La complicación más habitual en el
post-operatorio fue el derrame sinovial (3%) siendo necesaria al artrocentesis para su desaparición
en el plazo de 1-2 semanas.This work was aimed at presenting the results of 474 diagnostic artroscopies of
the knee performed in our Department of orthopaedic surgery from January 1988 to August
1992. The mean age of the patients was 32 years. There was a greater incidence in males
(73%). The most frequent pathologic finding was medial meniscopathy (48%). The mean period
of hospitalization was 3 days. There was an opposite relationship betwen the hospitalization
period and the age of the patient. As complications, synovial effusion was found in 3% of
cases, synovial fluid evacuation been necessary
Germinação de semente, embrião e eixo embrionário de sucupira branca (Pterodon pubescens Benth.) in vitro.
Resumo de trabalho apresentado no 7º Congresso Brasileiro de Fisiologia Vegetal, Brasília, julho 1999
Estabelecimento e multiplicação in vitro de segmento nodal de Sucupira branca (Pterodon pubescens Benth.).
Resumo de trabalho apresentado no 7º Congresso Brasileiro de Fisiologia Vegetal, Brasília, julho 1999
La prótesis de cadera con recubrimiento de vidrio Primeros resultados con 2 años de evolución
El presente trabajo analiza los primeros resultados clínicos y radiográficos de un
estudio con la prótesis de cadera no cementada con recubrimiento «de vidrio» a nivel metafísario
(prótesis CRM). La casuística comprende 80 artroplastias totales implantadas desde 1991 a 1994
con un seguimiento mínimo de 2 años. La evolución clínica, valorada según el sistema de Harris
modificado, ha sido satisfactoria en el 90% de los enfermos. La observación radiográfica ha mostrado
buena fijación y orientación de los componentes femorales en 72 casos. La conclusión de
este análisis preliminar permite apreciar que el recubrimiento protésico con cerámica de vidrio
supone un mecanismo de seguridad en la fijación primaria y secundaria de la prótesis de cadera.This work analizes the first clinical and radiological results of a cementless hip
prosthesis with glass coating at metaphyseal level (CRM prosthesis). A total of 80 arthroplasties implanted
since may 1991 to 1994 were studied with a two year follow-up. The clinical assesment was
done by the modified Harris score, being satisfactory in 90% of the patients. The radiological study
demonstrated good fixation and orientation of the prosthetic compounds in 72 cases. The prosthetic
model studied provides a security mechanism both for primary and secondary fixation of the
femoral stem and acetabular cup
Hubble Space Telescope WFPC-2 Imaging of Cassiopeia A
The young SNR Cassiopeia A was imaged with WFPC-2 through four filters
selected to capture the complete velocity range of the remnant's main shell in
several important emission lines. Primary lines detected were [O III]
4959,5007, [N II] 6583, [S II] 6716,6731 + [O II] 7319,7330 + [O I] 6300,6364,
and [S III] 9069,9532. About 3/4th of the remnant's main shell was imaged in
all four filters. Considerable detail is observed in the reverse-shocked ejecta
with typical knot scale lengths of 0.2"-0.4" (1 - 2 x 10^16 cm). Both bright
and faint emission features appear highly clumped. Large differences in [S III]
and [O III] line intensities indicating chemical abundance differences are also
seen, particularly in knots located along the bright northern limb and near the
base of the northeast jet. A line of curved overlapping filament in the
remnant's northwestern rim appears to mark the location of the remnant's
reverse shock front in this region. Finger-like ejecta structures elsewhere
suggest cases where the reverse shock front is encountering the remnant's
clumped ejecta. Narrow-band [N II] images of the remnant's circumstellar knots
("QSFs") reveal them to be 0.1"-0.6" thick knots and filaments, often with
diffuse edges facing away from the center of expansion. Three color composite
images of the whole remnant and certain sections along with individual filter
enlargements of selected regions of the bright optical shell are presented and
discussed.Comment: 26 pages, 12 figures Accepted to the Astronomical Journa
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