1,606 research outputs found
Molecule mapping of HR8799b using OSIRIS on Keck: Strong detection of water and carbon monoxide, but no methane
Context. In 2015, Barman et al. (ApJ, 804, 61) presented detections of
absorption from water, carbon monoxide, and methane in the atmosphere of the
directly imaged exoplanet HR8799b using integral field spectroscopy (IFS) with
OSIRIS on the Keck II telescope. We recently devised a new method to analyse
IFU data, called molecule mapping, searching for high-frequency signatures of
particular molecules in an IFU data cube.
Aims. The aim of this paper is to use the molecule mapping technique to
search for the previously detected spectral signatures in HR8799b using the
same data, allowing a comparison of molecule mapping with previous methods.
Methods. The medium-resolution H- and K-band pipeline-reduced archival data
were retrieved from the Keck archive facility. Telluric and stellar lines were
removed from each spectrum in the data cube, after which the residuals were
cross-correlated with model spectra of carbon monoxide, water, and methane.
Results. Both carbon monoxide and water are clearly detected at high
signal-to-noise, however, methane is not retrieved.
Conclusions. Molecule mapping works very well on the OSIRIS data of exoplanet
HR8799b. However, it is not evident why methane is detected in the original
analysis, but not with the molecule mapping technique. Possible causes could be
the presence of telluric residuals, different spectral filtering techniques, or
the use of different methane models. We do note that in the original analysis
methane was only detected in the K-band, while the H-band methane signal could
be expected to be comparably strong. More sensitive observations with the JWST
will be capable of confirming or disproving the presence of methane in this
planet at high confidence.Comment: 5 pages, 5 figures and 2 tables, accepted by A&
Entender y anotar los textos políticos de Quevedo: las exigencias de la Historia
La obras políticas de Quevedo fueron leídas con pasión por los lectores de su tiempo. Hoy, muchos críticos alaban su valor literario pero denuncian la trivialidad de sus propósitos. Tal contradicción se explica por un error de perspectiva que hace que se busque en los textos quevedianos un sentido “eterno” que no pueden tener porque son esencialmente productos de la historia y testimonios de su época.
The political works of Quevedo were read with passion in his time. Today, many critics, while praising their literary worth, denounce their commonplace content. Such contradictory judgement can be explained by the faulty angle of a search for an “eternal” truth into Quevedo’s texts, which they will not provide due to their being the pure products of the history and testimonies of their time. Backed up by her own researches, Josette Riandière points out how incumbent is on the publisher to acquire the historical knowledge —be it philological, semantic, political, scientific, etc.— which requires a correct comprehension of these texts, both literal and ideological, so as to place them within the gasp of the modern reader
Quevedo y la Santa Sede: problemas de coherencia ideológica y de edición
Al cotejar la Carta de Fernando el Católico al primer virrey de Nápoles (1621) con la primera parte de Política de Dios (1626), y con la segunda parte, póstuma, de dicha obra (1655), se podría sospechar que, con los años, cambió por completo la opinión de Quevedo referente al poder respectivo del papa y del monarca español en los territorios dependientes de España. Se intenta mostrar que en 1635, como en 1621-1630, Quevedo seguía defendiendo las regalías de España. Cotejando la versión manuscrita de Política (II), escrita hacia 1635, con la versión ampliada de dicha obra, editada en 1655, se intenta evidenciar que la contradicción ideológica aludida, solo aparente, se debe a que los primeros editores de Política (II) manipularon los preliminares y algunos pasajes del texto quevediano.
If we compare the Carta de Fernando el Católico al primer virrey de Nápoles (1621) with the first part of Política de Dios and with the posthumous second part of this work (published in 1655), we could assume that Quevedo changed completely his opinion about the power of the Papacy and the Spanish kings in the domains ruled by Spain. The author tries to prove that Quevedo defended the royal prerogatives in 1635 as he did between 1621-1630. A careful collation of the manuscript version of Política (II), written around 1635, and the enlarged version of this work published in 1655 shows that the ideological contradiction is only apparent. This inconsistency was caused because the first editors of Política (II) manipulated the preambles and some passages of Quevedo’s text
Probing deviations from General Relativity with the Euclid spectroscopic survey
We discuss the ability of the planned Euclid mission to detect deviations
from General Relativity using its extensive redshift survey of more than 50
Million galaxies. Constraints on the gravity theory are placed measuring the
growth rate of structure within 14 redshift bins between z=0.7 and z=2. The
growth rate is measured from redshift-space distortions, i.e. the anisotropy of
the clustering pattern induced by coherent peculiar motions. This is performed
in the overall context of the Euclid spectroscopic survey, which will
simultaneously measure the expansion history of the universe, using the power
spectrum and its baryonic features as a standard ruler, accounting for the
relative degeneracies of expansion and growth parameters. The resulting
expected errors on the growth rate in the different redshift bins, expressed
through the quantity f\sigma_8, range between 1.3% and 4.4%. We discuss the
optimisation of the survey configuration and investigate the important
dependence on the growth parameterisation and the assumed cosmological model.
We show how a specific parameterisation could actually drive the design towards
artificially restricted regions of the parameter space. Finally, in the
framework of the popular "\gamma -parameterisation", we show that the Euclid
spectroscopic survey alone will already be able to provide substantial evidence
(in Bayesian terms) if the growth index differs from the GR value \gamma=0.55
by at least \sim 0.13. This will combine with the comparable inference power
provided by the Euclid weak lensing survey, resulting in Euclid's unique
ability to provide a decisive test of modified gravity.Comment: 18 pages, 15 figures, accepted by MNRA
Molecular dynamics simulation of the nanoindentation process in Cr/CrN and (Cr/CrN)2 thin films
Molecular dynamics (MD) simulations were carries out for studying the influenceof nanoindentation in the atomistic deformation mechanisms of Cr/CrN and(Cr/CrN)2 coatings with BCC and FCC crystalline structures for Cr and CrN,respectively. The Morse potential was employed in order to determine the atomicinteraction forces of the Cr-Cr and Cr-N atoms. A non-deformable potential solidsphere was implemented for determining the role of the nanoindenter. The OliverParr method (OP) was used to obtain the hardness and elastic modulus of the Cr/CrN and (Cr/CrN)2 layers, resulting in values of 18 and 20 GPa for Cr/CrN and (Cr/CrN)2, respectively. The Cheng method was used for correcting the hardness values obtained by the OP method. The Cheng correction showed higher hardness values since it avoids the influence of the scale effect. Regarding the elasticity modulus, Cr/CrN and (Cr/CrN)2 exhibited values of 217.86 GPa and 258.9 GPa, respectively. Simulations of the temperature influence on the hardness were carried out over a range of 300-1000 K. Results indicate that the hardness decreased as a function of the temperature.Fil: Amaya Roncancio, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Arias Mateus, D. F.. Universidad Católica de Pereira; ColombiaFil: Segura Giraldo, B.. Universidad Nacional de Colombia; ColombiaFil: de la Roche, J.. Universidad Nacional de Colombia; ColombiaFil: Restrepo Parra, E.. Universidad Nacional de Colombia; Colombi
Why every observatory needs a disco ball
Commercial disco balls provide a safe, effective and instructive way of
observing the Sun. We explore the optics of solar projections with disco balls,
and find that while sunspot observations are challenging, the solar disk and
its changes during eclipses are easy and fun to observe. We explore the disco
ball's potential for observing the moon and other bright astronomical
phenomena.Comment: 6 pages, 7 figures. Submitted to Physics Education. Comments welcom
Telomere lengths in human oocytes, cleavage stage embryos and blastocysts
Telomeres are repeated sequences that protect the ends of chromosomes and harbour DNA-repair proteins. Telomeres shorten during each cell division in the absence of telomerase. When telomere length becomes critically short, cell senescence occurs. Telomere length therefore reflects both cellular ageing and capacity for division. We have measured telomere length in human germinal vesicle (GV) oocytes and pre-implantation embryos, by quantitative fluorescence in-situ hybridisation (Q-FISH), providing baseline data towards our hypothesis that telomere length is a marker of embryo quality. The numbers of fluorescent foci suggest that extensive clustering of telomeres occurs in mature GV stage oocytes, and in pre-implantation embryos. When calculating average telomere length by assuming that each signal presents one telomere, the calculated telomere length decreased from the oocyte to the cleavage stages, and increased between the cleavage stages and the blastocyst (11.12 vs 8.43 vs 12.22kb respectively, p<0.001). Other methods of calculation, based upon expected maximum and minimum numbers of telomeres, confirm that telomere length in blastocysts is significantly longer than cleavage stages. Individual blastomeres within an embryo showed substantial variation in calculated average telomere length. This study implies that telomere length changes according to the stage of pre-implantation embryo development
High-precision multi-band measurements of the angular clustering of X-ray sources
In this paper we present the two-point angular correlation function of the
X-ray source population of 1063 XMM-Newton observations at high Galactic
latitudes, comprising up to ~30000 sources over a sky area of 125.5 sq. deg, in
three energy bands: 0.5-2 (soft), 2-10 (hard), and 4.5-10 (ultrahard) keV. We
have measured the angular clustering of our survey and find significant
positive clustering signals in the soft and hard bands, and a marginal
clustering detection in the ultrahard band. We find dependency of the
clustering strength on the flux limit and no significant differences in the
clustering properties between sources with high hardness ratios and those with
low hardness ratios. Our results show that obscured and unobscured objects
share similar clustering properties and therefore they both reside in similar
environments, in agreement with the unified model of AGN. We deprojected the
angular clustering parameters via Limber's equation to compute their typical
spatial lengths. From that we have inferred the typical mass of the dark matter
haloes in which AGN at redshifts of ~1 are embedded. The short AGN lifetimes
derived suggest that AGN activity might be a transient phase that can be
experienced several times by a large fraction of galaxies throughout their
lives.Comment: 14 pages, 9 figures, accepted for publication in Astronomy and
Astrophysic
The presence and predictors of complicated grief symptoms in perinatally-bereaved mothers from a bereavement support organization
The present study investigated the presence and possible predictors of complicated grief symptoms in perinatally-bereaved mothers (N = 121) up to 5 years post-bereavement. The presence of complicated grief scores in the clinical range was 12.4%, which is higher than in many other bereaved populations, and the presence of other living children may protect against the development of complicated grief symptoms. The majority of the women were able to negotiate a perinatal loss without developing complicated grief; however, there remains an important group of women who up to 5 years later score in the clinical range for complicated grief symptoms
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