4,630 research outputs found
The onset of solar cycle 24: What global acoustic modes are telling us
We study the response of the low-degree, solar p-mode frequencies to the
unusually extended minimum of solar surface activity since 2007. A total of
4768 days of observations collected by the space-based, Sun-as-a-star
helioseismic GOLF instrument are analyzed. A multi-step iterative
maximum-likelihood fitting method is applied to subseries of 365 days and 91.25
days to extract the p-mode parameters. Temporal variations of the l=0, 1, and 2
p-mode frequencies are then obtained from April 1996 to May 2009. While the
p-mode frequency shifts are closely correlated with solar surface activity
proxies during the past solar cycles, the frequency shifts of the l=0 and l=2
modes show an increase from the second half of 2007, when no significant
surface activity is observable. On the other hand, the l=1 modes follow the
general decreasing trend of the solar surface activity. The different
behaviours between the l=0 and l=2 modes and the l=1 modes can be interpreted
as different geometrical responses to the spatial distribution of the solar
magnetic field beneath the surface of the Sun. The analysis of the low-degree,
solar p-mode frequency shifts indicates that the solar activity cycle 24
started late 2007, despite the absence of activity on the solar surface.Comment: To be accepted by A&A (with minor revisions), 4 pages, 3 figures, 1
tabl
An infrared study of galactic OH/IR stars. I. An optical/near-IR atlas of the Arecibo sample
In this paper we present optical and near-infrared finding charts, accurate
astrometry (~1") and single-epoch near-infrared photometry for 371 IRAS
sources, 96% of those included in the so-called Arecibo sample of OH/IR stars
(Eder et al. 1988; Lewis et al. 1990a; Chengalur et al. 1993). The main
photometric properties of the stars in the sample are presented and discussed
as well as the problems found during the process of identification of the
optical/near-infrared counterparts. In addition, we also identify suitable
reference stars in each field to be used for differential photometry purposes
in the future.
We find that 39% of the sources (144 in number) have no optical counterpart,
8 of them being invisible even at near infrared wavelengths. The relative
distribution of sources with and without optical counterpart in the IRAS
two-colour diagram and their characteristic near infrared colours are
interpreted as the consequence of the increasing thickness of their
circumstellar shells. Among the objects not detected at near infrared
wavelengths four non-variable sources are proposed to be heavily obscured
post-AGB stars which have just very recently left the AGB. Eight additional
objects with unusually bright and/or blue near-infrared colours are identified
as candidate post-AGB stars and/or proto-planetary nebulae.Comment: 28 pages, 9 figures, for associated finding charts see:
http://www.edpsciences.org/articles/aa/full/2005/08/aa1709/FINDING_CHARTS/are
cibo_index.htm
The Quasi-Biennial Periodicity (QBP) in velocity and intensity helioseismic observations
We looked for signatures of Quasi-Biennial Periodicity (QBP) over different
phases of solar cycle by means of acoustic modes of oscillation. Low-degree
p-mode frequencies are shown to be sensitive to changes in magnetic activity
due to the global dynamo. Recently have been reported evidences in favor of
two-year variations in p-mode frequencies. Long high-quality helioseismic data
are provided by BiSON (Birmingham Solar Oscillation Network), GONG (Global
Oscillation Network Group), GOLF (Global Oscillation at Low Frequency) and
VIRGO (Variability of Solar IRradiance and Gravity Oscillation) instruments. We
determined the solar cycle changes in p-mode frequencies for spherical degree
l=0, 1, 2 with their azimuthal components in the frequency range 2.5 mHz < nu <
3.5 mHz. We found signatures of QBP at all levels of solar activity in the
modes more sensitive to higher latitudes. The signal strength increases with
latitude and the equatorial component seems also to be modulated by the 11-year
envelope. The persistent nature of the seismic QBP is not observed in the
surface activity indices, where mid-term variations are found only time to time
and mainly over periods of high activity. This feature together with the
latitudinal dependence provides more evidences in favor of a mechanism almost
independent and different from the one that brings up to the surface the active
regions. Therefore, these findings can be used to provide more constraints on
dynamo models that consider a further cyclic component on top of the 11-year
cycle.Comment: 9 pages, 9 Figures, 2 Tables Accepted for publication in A&
On the ubiquity of trivial torsion on elliptic curves
The purpose of this paper is to give a "down--to--earth" proof of the
well--known fact that a randomly chosen elliptic curve over the rationals is
most likely to have trivial torsion
On the evolutionary connection between AGB stars and PNe
The `O-rich AGB sequence' is a sequence of colours describing the location of
O-rich AGB stars in the IRAS two-colour diagram [12]--[25] vs [25]--[60]. We
propose an evolutionary scenario for this sequence in which all stars,
independent of their progenitor mass, start the AGB phase in the blue part of
the `O-rich AGB sequence' and then evolve toward redder colors, although only
the more massive stars would reach the very end of the `O-rich AGB sequence'.
The sources located in the blue part of the sequence are mainly Mira variables,
whose mean period is increasing with the IRAS colours. Most of them will evolve
into O-rich Type II (and III) Planetary Nebulae. Part of the stars located in
the red part of the sequence will change their chemical composition from O-rich
to C-rich during their evolution in the AGB phase, and might evolve into C-rich
Type II Planetary Nebulae. Hot bottom burning may prevent the conversion to
carbon stars of the rest of sources located in the red part of the sequence and
they will end up as N-rich Type I Planetary Nebulae.Comment: 4 pages, 6 figures, proceedings of the conference 'Planetary Nebulae
as Astrophysical Tools', held in Gdansk, Poland (June 28 - July 2, 2005
Determination of the influence of specific building regulations in smart buildings
The automation of domestic services began to be implemented in buildings since the late nineteenth century, and today we are used to terms like âintelligent buildingsâ, âdigital homeâ or âdomotic buildingsâ. These concepts tell us about constructions which integrate
new technologies in order to improve comfort, optimize energy consumption or enhance the security of users. In conjunction, building regulations have been updated to suit the needs of society and to regulate these new facilities in such structures. However, we are not always
sure about how far, from the quantitative or qualitative point of view, legislation should
regulate certain aspects of the building activity. Consequently, content analysis is adopted in
this research to determine the influence of building regulations in the implementation of
new technologies in the construction process. This study includes the analysis of different
European regulations, the collection and documentation of such guidelines that have been
established and a study of the impact that all of these have had in the way we start thinking an architectural project. The achievements of the research could be explained in terms of the regulatory requirements that must be taken into account in order to achieve a successful implementation of a home automation system, and the key finding has been the confirmation of how the design of smart buildings may be promoted through specific regulatory requirements while other factors, such as the global economic situation, do not seem to affect directly the rate of penetration of home automation in construction
GestiĂłn de espacios y eventos culturales (GEEC)
El principal objetivo del proyecto es elaborar un sistema informĂĄtico que permita gestionar los espacios y
los eventos culturales que puedan interesar a los distintos tipos de entidades que se encargan de
planificar u organizar estos aspectos. Dicho sistema debe cumplir los siguientes requisitos bĂĄsicos:
1. Estudio y anĂĄlisis del sistema de gestiĂłn de espacios y eventos culturales.
2. Estudio de la tecnologĂa utilizada para la implementaciĂłn de una arquitectura base, y que
permita la implementación råpida, sencilla y basada en eståndares del desarrollo web que estén
ampliamente extendidos, lo cual permitirĂĄ encontrar documentaciĂłn suficiente en caso de ser
necesario. EvaluaciĂłn de las ventajas e inconvenientes y justificaciĂłn de la elecciĂłn de los
frameworks de desarrollo utilizados para la implementaciĂłn del proyecto.
3. AnĂĄlisis y diseño de los mĂłdulos necesarios para la gestiĂłn de espacios y eventos culturales.IngenierĂa TĂ©cnica en InformĂĄtica de GestiĂł
Toward a clinical practice guide in pharmacogenomics testing for functional polymorphisms of drug-metabolizing enzymes. Gene/drug pairs and barriers perceived in Spain
The development of clinica lpractice recommendations or
guidelines for the clinical use of biomarkers is an issue of great importance withr regard to adverse drug reactions.The poten-tial of pharmacogenomicbiomarkers has been extensively investigated in recent years.However,several barriers to implementing the use of pharmacogenomics testing exist.We conducted a survey among members of the Spanish Societies of Pharmacology and Clinical Pharmacology to obtain information about the perception of such barriers and to compare the perceptions of participants about the relative importance of majorgene/drug pairs.Of 11 potential barriers,the highest importance was attributed to lack of institutional support for pharmacogenomic stesting,and to the issues related to the lack of guidelines.Of the proposed gene/drug pairs the highest importance was assigned to HLA-B/abacavir, UGT1A1/irinotecan, and CYP2D6/tamoxifen.In this perspective article,we compare the relative importance of 29 gene/drugpairs in the Spanish study with that of the same pairs in the American Society for Clinical Pharmacology and Therapeutic sstudy,and we provide suggestions and areas of focus to develop a guide for clinical practice in pharmacogenomics testingThe work in the authorâs laboratory is financed by Grants
PS09/00943, PS09/00469, RETICS RIRAAF RD07/0064/0016,
and CIBERehd from Instituto de Salud CarlosIII,Madrid,
Spain, and by Grants GR10068 from Junta de Extremadura,
Spain. Financed in part with FEDER funds from the European
Unio
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