2,548 research outputs found
On the origin of two unidentified radio/X-ray sources discovered with XMM-Newton
We aim at clarifying the nature of the emission of two spatially related
unidentified X-ray sources detected with XMM-Newton telescope at
intermediate-low Galactic latitude. Observations reveal a point-like source
aligned with elongated diffuse emission. The X-ray spectra are best-fitted by
absorbed power laws with photon indices ~1.7 for the point-like and ~2.0 for
the extended one. Both sources show nonthermal radio-continuum counterparts
that might indicate a physical association. From the available data, we did not
detect variability on the point-like source in several timescales. Two possible
scenarios are analyzed: first, based on HI line absorption, assuming a Galactic
origin, we infer a distance upper bound of <2 kpc, which poses a constraint on
the height over the Galactic plane of <200 pc and on the linear size of the
system of 10^32 erg/s and
>7.5 x 10^32 erg/s, for the point-like and extended sources, respectively;
second, an extra-Galactic nature is discussed, where the point-like source
might be the core of a radio galaxy and the extended source its lobe. In this
case, we compare derived fluxes, spectral indices, and spatial correlation with
those typical from the radio galaxy population, showing the feasibility of this
alternative astrophysical scenario. From the available observational evidence,
we suggest that the most promising scenario to explain the nature of these
sources is a system consisting of a one-sided radio galaxy, where the
point-like source is an active galactic nucleus and the extended source
corresponds to the emission from its lobe. Other possibilities include a
PSR/PWN origin, where the radio/X-ray emission originates from the synchrotron
cooling of relativistic particles in the PSR magnetic field or a casual
alignment between two unrelated sources, such as an AGN core and a Galactic
X-ray blob.Comment: 6 pages, 2 figures. Accepted for publication in Astronomy and
Astrophysics (A&A
THROES: a caTalogue of HeRschel Observations of Evolved Stars. I. PACS range spectroscopy
This is the first of a series of papers presenting the THROES (A caTalogue of
HeRschel Observations of Evolved Stars) project, intended to provide a
comprehensive overview of the spectroscopic results obtained in the
far-infrared (55-670 microns) with the Her- schel space observatory on
low-to-intermediate mass evolved stars in our Galaxy. Here we introduce the
catalogue of interactively reprocessed PACS (Photoconductor Array Camera and
Spectrometer) spectra covering the 55-200 microns range for 114 stars in this
category for which PACS range spectroscopic data is available in the Herschel
Science Archive (HSA). Our sample includes objects spanning a range of
evolutionary stages, from the asymptotic giant branch to the planetary nebula
phase, displaying a wide variety of chemical and physical properties. The
THROES/PACS catalogue is accessible via a dedicated web-based inter- face
(https://throes.cab.inta-csic.es/) and includes not only the science-ready
Herschel spectroscopic data for each source, but also complementary photometric
and spectroscopic data from other infrared observatories, namely IRAS (Infrared
Astronomical Satellite), ISO (Infrared Space Observatory) or AKARI, at
overlapping wavelengths. Our goal is to create a legacy-value Herschel dataset
that can be used by the scientific community in the future to deepen our
knowledge and understanding of these latest stages of the evolution of
low-to-intermediate mass stars.Comment: 38 page
Evaluacion de 10 variedades de papas nativas para producir semilla pre basica bajo un sistema hidroponico.
Full transmission through perfect-conductor subwavelength hole arrays
Light transmission through 2D subwavelength hole arrays in perfect-conductor
films is shown to be complete (100%) at some resonant wavelengths even for
arbitrarily narrow holes. Conversely, the reflection on a 2D planar array of
non-absorbing scatterers is shown to be complete at some wavelengths regardless
how weak the scatterers are. These results are proven analytically and
corroborated by rigorous numerical solution of Maxwell's equations. This work
supports the central role played by dynamical diffraction during light
transmission through subwavelength hole arrays and it provides a systematics to
analyze more complex geometries and many of the features observed in connection
with transmission through hole arrays.Comment: 5 pages, 4 figure
Warm CO in evolved stars from the THROES catalogue. II. Herschel/PACS spectroscopy of C-rich envelopes
This is the second paper of a series making use of Herschel/PACS spectroscopy
of evolved stars in the THROES catalogue to study the inner regions of their
circumstellar envelopes (CSEs). We analyze the CO emission spectra, including a
large number of high- CO lines (from =14-13 to =45-44), as a proxy for
the warm molecular gas in the CSEs of a sample of bright carbon-rich stars
spanning different evolutionary stages from the Asymptotic Giant Branch (AGB)
to the young planetary nebulae (PNe) phase. We use the rotational diagram (RD)
to derive rotational temperatures () and masses () of
the envelope layers where the CO transitions arise. We also obtain a first
order estimate of the mass-loss rates and assess the impact of the opacity
correction for a range of characteristic envelope radii. We use multi-epoch
spectra for the well studied C-rich envelope IRC+10216 to investigate the
impact of CO flux variability on the values of and .
PACS sensitivity allowed the study of higher rotational numbers than before,
indicating the presence of a significant amount of warmer gas (200-900 K)
not traceable with lower- CO observations at sub-mm/mm wavelengths. The
masses are in the range , anti-correlated
with temperature. For some strong CO emitters we infer a double temperature
(warm 400 K and hot 820 K) component. From
the analysis of IRC+10216, we corroborate that the effect of line variability
is perceptible on the of the hot component only, and certainly
insignificant on and, hence, the mass-loss rate. Therefore, the
parameters derived from the RD are robust even when strong line flux
variability occurs, with the major source of uncertainty in the estimate of the
mass-loss rate being the size of the CO-emitting volume.Comment: accepted in A&
Degradación de la Clorofila Presente en (Spirogyra spp.) como Indicator Socio Ambiental de la Presencia de Plaguicidas organofosforados
En la presente investigación se estudió la alteración de la clorofila presente en Spirogyra spp. como indicador de la presencia de tres plaguicidas organofosforados: Curacrón, Malatión y Acefato, a través de ensayos realizados a diferentes concentraciones de los plaguicidas durante un lapso de 72 horas de exposición. Transcurrida la etapa experimental se pudo observar la pérdida de la coloración verde de las algas como resultado de la alteración de su pigmentación natural. El análisis de varianza realizado a los resultados de la medición de la absorbancia de las muestras demuestra una disminución de la concentración de clorofila, en comparación con las muestras testigo de los ensayos. La sensibilidad de las algas al ser expuestas a los plaguicidas organofosforados es una manifestación del alto potencial bioindicador de Spirogyra spp. Este estudio brinda a los agricultores de la comunidad de San Antonio la posibilidad de detectar de manera temprana la presencia de plaguicidas en sus fuentes de agua y abre las puertas a la investigación para posteriores aplicaciones. The alteration of the chlorophyll present in Spirogyra spp. was studied as an indicator of the presence of three organophosphorus pesticides, Curacron, Malathion and Acephate, with tests carried out at different concentrations of the pesticides during a period of 72 hours of exposure. After the experimental stage, it was possible to observe the loss of the green coloration of the algae as a result of the alteration of their natural pigmentation. The analysis of variance based on the results of the measurement of the absorbance of the samples demonstrated a decrease in the concentration of chlorophyll compared to the control samples from the trials. The sensitivity of algae to being exposed to organophosphorus pesticides is a manifestation of the high bioindicator potential of Spirogyra spp., which provides farmers in the community of San Antonio the possibility of early detection of the presence of pesticides in their sources of water, and it also opens the doors to research for subsequent applications
Influence of curing conditions on recycled aggregate concrete
This paper presents the results of a study of permeability and its influence on the durability of recycled concrete exposed to an aggressive environment. Recycled concretes with 20%, 50% and 100% in weight ofrecycled aggregate and 24 effective w/c ratios have been exposed directly to a marine environment. Control specimens cured in a humidity chamber have been also tested in order to compare the influence of the curing environment. The durability of recycled aggregate concretes exposed to aggressive conditions decreases in terms of permeability, as the results show. However, the influence of the environment on the recycled concrete also depends on the quality of the cement paste. The differences between the control and the exposed concrete are lower for low water/cement (w/c) ratios. The lower capillarity obtained in the new cement paste of the recycled concretes with low w/c ratios isolates the porosity of the recycled aggregate, increasing the durability but with a rise in the cement content.The authors wish to thank the Spanish Ministry of the Environment for the funding of this research. The results contained herein have been achieved under the RECNHOR Project (funded by the Spanish Ministry of Environment) and under the CLEAM Project (funded by the Spanish Centre for Industrial Technology Development, CDTI), Code 3.2-358/200 5/3-B, led by the Economic InterestGrouping CLEAM-CENIT, AIE (Acciona, Dragados, Ferrovial, FCC,Sioux, OHL and Sacyr) and SMEs Informatica 68, Quilosa and Martinez Segovia and associates
Nearby supernova host galaxies from the CALIFA survey: II. Supernova environmental metallicity
The metallicity of a supernova progenitor, together with its mass, is one of the main parameters that can rule the progenitor's fate. We present the second study of nearby supernova (SN) host galaxies (0.005 10 dex) by targeted searches. We neither found evidence that the metallicity at the SN location differs from the average metallicity at the galactocentric distance of the SNe. By extending our SN sample with published metallicities at the SN location, we are able to study the metallicity distributions for all SN subtypes split into SN discovered in targeted and untargeted searches. We confirm a bias toward higher host masses and metallicities in the targeted searches. By combining data from targeted and untargeted searches, we found a sequence from higher to lower local metallicity: SN Ia, Ic, and II show the highest metallicity, which is significantly higher than those of SN Ib, IIb, and Ic-BL. Our results support the scenario according to which SN Ib result from binary progenitors. Additionally, at least part of the SN Ic are the result of single massive stars that were stripped of their outer layers by metallicity-driven winds. We studied several proxies of the local metallicity that are frequently used in the literature and found that the total host metallicity allows estimating the metallicity at the SN location with an accuracy better than 0.08 dex and very small bias. In addition, weak AGNs that cannot be seen in the total spectrum may weakly bias (by 0.04 dex) the metallicity estimate that is derived from the galaxy-integrated spectrum. © ESO, 2016.This work was partly funded by FCT with the research grant PTDC/CTE-AST/112582/2009. Support for L.G. is partially provided by FCT, by CONICYT through FONDECYT grant 3140566, and from the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC12009, awarded to The Millennium Institute of Astrophysics (MAS). V.S. acknowledges financial support from Fundacao para a Ciencia e a Tecnologia (FCT) under program Ciencia 2008. C.J.W. acknowledges support through the Marie Curie Career Integration Grant 303912.Peer Reviewe
Treatment with zygomatic implants in patients with advanced atrophy of maxilla
Introducción. El objetivo del presente estudio era mostrar los resultados del tratamiento con implantes cigomáticos
utilizados en pacientes con atrofia maxilar severa.
Metodos. 18 pacientes fueron tratados con 36 implantes cigomáticos Galimplant ® sumergidos con conexión interna
para su rehabilitación prostodóncica. Las técnicas quirúrgicas de inserción de cigomáticos fueron extrasinusal y la
técnica de la ranura sinusal. Los implantes fueron cargados después de un periodo de cicatrización de 6 meses.
Resultados. Los hallazgos clínicos indican una supervivencia de los implantes del 100%. 14 implantes (38,9%) se in-
sertaron por via extrasinusal y 22 implantes (61,6%) por la técnica de la ranura sinusal. Un total de 18 prótesis híbridas
atornilladas fueron realizadas. Complicaciones postoperatorias fueron observadas en 4 pacientes (22,2%). El periodo
medio de seguimiento clínico ha sido de 12 meses.
Conclusiones. Este estudio indica que los implantes cigomáticos pueden ser utilizados con éxito en el tratamiento de
los pacientes con atrofia maxilar severaThe aim of this study was to report the outcome of treatment with zygomatic implants used in
patients with severe atrophy of maxilla.
Methods. 18 patients were treated with 36 Galimplant ® zygomatic implants with internal connection for
prosthodontic rehabilitation. Zygomatic surgical techniques were two approach for insertion of implants,
extrasinusal and sinus slot technique. Implants were loaded after a healing free-loading period of six months.
Results. Clinical results indicate a survival rate of implants of 100%. Fourteen implants (38.9%) were inser-
ted by extrasinusal approach while twenty two implants were inserted by sinus slot approach (61.1%). A total of 18 hybrid screw prostheses were realized. Postoperative complications were observed in four patients
(22.2%). The mean follow-up period were 12 months.
Conclusions. This study indicate that zygomatic implants can be used with success in treatment of patients
with severe atrophic maxilla
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