187 research outputs found
Is the X(3872) Production Cross Section at Tevatron Compatible with a Hadron Molecule Interpretation?
The X(3872) is universally accepted to be an exotic hadron. In this letter we
assume that the X(3872) is a D0 \bar D0* molecule, as claimed by many authors,
and attempt an estimate of its prompt production cross section at Tevatron. A
comparison with CDF data allows to draw some qualitative conclusions about this
statement.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let
Survival of patients with spinal muscular atrophy type 1
BACKGROUND: Spinal muscular atrophy type 1 (SMA1) is a progressive disease and is usually fatal in the first year of life. METHODS: A retrospective chart review was performed of SMA1 patients and their outcomes according to the following choices: letting nature take its course (NT); tracheostomy and invasive mechanical ventilation (TV); continuous noninvasive respiratory muscle aid (NRA), including noninvasive ventilation; and mechanically assisted cough. RESULTS: Of 194 consecutively referred patients enrolled in this study (103 males, 91 females), NT, TV, and NRA were chosen for 121 (62.3%), 42 (21.7%), and 31 (16%) patients, respectively. Survival at ages 24 and 48 months was higher in TV than NRA users: 95% (95% confidence interval: 81.8%-98.8%) and 67.7% (95% confidence interval: 46.7%-82%) at age 24 months (P < .001) and 89.43% and 45% at age 48 months in the TV and NRA groups, respectively (P < .001). The choice of TV decreased from 50% (1992-1998) to 12.7% (2005-2010) (P < .005) with a nonstatistically significant increase for NT from 50% to 65%. The choice of NRA increased from 8.1% (1999-2004) to 22.7% (2005-2010) (P < .001). CONCLUSIONS: Long-term survival outcome is determined by the choice of the treatment. NRA and TV can prolong survival, with NRA showing a lower survival probability at ages 24 and 48 months. Copyright © 2013 by the American Academy of Pediatrics
A possibly inflated planet around the bright, young star DS Tuc A
The origin of the observed diversity of planetary system architectures is one
of the main topic of the exoplanetary research. The detection of a
statistically significant sample of planets around young stars allows us to
study the early stages of planet formation and evolution, but only a handful of
them is known so far. In this regard, a considerable contribution is expected
from the NASA TESS satellite, which is now performing a survey of
of the sky to search for short-period transiting planets In its first month of
operations, TESS found a planet candidate with an orbital period of 8.14 days
around a member of the Tuc-Hor young association ( 40 Myr), the G6V main
component of the binary system DS\,Tuc. If confirmed, it would be the first
transiting planet around a young star suitable for radial velocity and/or
atmospheric characterization. We aim to validate the planetary nature of this
companion and to measure its orbital and physical parameters. We obtain
accurate planet parameters by coupling an independent reprocessing of the TESS
light curve with improved stellar parameters and the dilution caused by the
binary companion; we analyse high precision archival radial velocities to
impose an upper limit of about 0.1 M on the planet mass; we finally
rule out the presence of external companions beyond 40 au with adaptive optics
images. We confirm the presence of a young, giant ( R) planet having a not negligible possibility to be inflated (theoretical
mass M) around DS\,Tuc~A. We discuss the feasibility
of mass determination, Rossiter-McLaughlin analysis and atmosphere
characterization, allowed by the brightness of the star.Comment: 12 pages, 11 figures. Accepted for publication in A&
Italian pediatric respiratory society recommendations on pediatric pulmonary function testing during COVID-19 pandemic.
The coronavirus disease 2019 (COVID-19) is a public health emergency of international concern caused by a newly discovered coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2). Person-toperson transmission of SARS-CoV-2 occurs primarily through close contact with an infected person, mainly occurring via respiratory droplets and after touching contaminated objects. Accordingly, pulmonary function testing (PFT) could be considered at high-risk for viral transmission due to the potential for coughing and droplet formation during PFT procedures. The most likely surfaces for possible contamination by this route are mouthpieces, proximal valves, and tubing. Also, both technical and clinical staff are usually in close contact with the patient during PFT for achieving optimal cooperation and best results. Effective prevention and control strategies are mandatory to prevent SARS-CoV-2 infection in the PFT laboratories. The Italian Pediatric Respiratory Society (IPRS) promotes a series of new recommendations that should be followed by healthcare workers in PFT laboratories during the COVID-19 pandemic
HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals
Short- to mid-term magnetic phenomena on the stellar surface of M-type stars
cannot only resemble the effects of planets in radial velocity data, but also
may hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942
taken over the past five years and additional photometry to disentangle stellar
activity effects from genuine Doppler signals as a result of the orbital motion
of the star around the common barycenter with its planet. To achieve this, we
use the common methods of pre-whitening, and treat the correlated red noise by
a first-order moving average term and by Gaussian-process regression following
an MCMC analysis. We identify the rotational period of the star at 16.3 days
and discover a new super-Earth, GJ 3942 b, with an orbital period of 6.9 days
and a minimum mass of 7.1 Me. An additional signal in the periodogram of the
residuals is present but we cannot claim it to be related to a second planet
with sufficient significance at this point. If confirmed, such planet candidate
would have a minimum mass of 6.3 Me and a period of 10.4 days, which might
indicate a 3:2 mean-motion resonance with the inner planet
The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
The distribution of exoplanets around low-mass stars is still not well
understood. Such stars, however, present an excellent opportunity of reaching
down to the rocky and habitable planet domains. The number of current
detections used for statistical purposes is still quite modest and different
surveys, using both photometry and precise radial velocities, are searching for
planets around M dwarfs. Our HARPS-N red dwarf exoplanet survey is aimed at the
detection of new planets around a sample of 78 selected stars, together with
the subsequent characterization of their activity properties. Here we
investigate the survey performance and strategy. From 2700 observed spectra, we
compare the radial velocity determinations of the HARPS-N DRS pipeline and the
HARPS-TERRA code, we calculate the mean activity jitter level, we evaluate the
planet detection expectations, and we address the general question of how to
define the strategy of spectroscopic surveys in order to be most efficient in
the detection of planets. We find that the HARPS-TERRA radial velocities show
less scatter and we calculate a mean activity jitter of 2.3 m/s for our sample.
For a general radial velocity survey with limited observing time, the number of
observations per star is key for the detection efficiency. In the case of an
early M-type target sample, we conclude that approximately 50 observations per
star with exposure times of 900 s and precisions of about 1 m/s maximizes the
number of planet detections
The GAPS Programme with HARPS-N at TNG VIII: Observations of the Rossiter-McLaughlin effect and characterisation of the transiting planetary systems HAT-P-36 and WASP-11/HAT-P-10
We determine the true and the projected obliquity of HAT-P-36 and
WASP-11/HAT-P-10 systems, respectively, which are both composed of a relatively
cool star and a hot-Jupiter planet. Thanks to the high-resolution spectrograph
HARPS-N, we observed the Rossiter-McLaughlin effect for both the systems by
acquiring precise radial-velocity measurements during planetary transit events.
We also present photometric observations comprising six light curves covering
five transit events, obtained using three medium-class telescopes and the
telescope-defocussing technique. One transit of WASP-11/HAT-P-10 was followed
simultaneously from two observatories. The three transit light curves of
HAT-P-36b show anomalies that are attributable to starspot complexes on the
surface of the parent star, in agreement with the analysis of its spectra that
indicate a moderate activity. By analysing the complete HATNet data set of
HAT-P-36, we estimated the stellar rotation period by detecting a periodic
photometric modulation in the light curve caused by star spots, obtaining
Prot=15.3 days, which implies that the inclination of the stellar rotational
axis with respect to the line of sight is 65 degree. We used the new
spectroscopic and photometric data to revise the main physical parameters and
measure the sky-projected misalignment angle of the two systems. We found
\lambda=-14 degree for HAT-P-36 and \lambda=7 degree for WASP-11/HAT-P-10,
indicating in both cases a good spin-orbit alignment. In the case of HAT-P-36,
we also measured its real obliquity, which turned out to be 25 degrees.Comment: 18 pages, 14 figure
Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b - First data from the GIARPS Commissioning
Context. Stellar activity is currently challenging the detection of young
planets via the radial velocity (RV) technique. Aims. We attempt to
definitively discriminate the nature of the RV variations for the young active
K5 star BD+20 1790, for which visible (VIS) RV measurements show divergent
results on the existence of a substellar companion. Methods. We compare VIS
data with high precision RVs in the near infrared (NIR) range by using the
GIANO - B and IGRINS spectrographs. In addition, we present for the first time
simultaneous VIS-NIR observations obtained with GIARPS (GIANO - B and HARPS -
N) at Telescopio Nazionale Galileo (TNG). Orbital RVs are achromatic, so the RV
amplitude does not change at different wavelengths, while stellar activity
induces wavelength-dependent RV variations, which are significantly reduced in
the NIR range with respect to the VIS. Results. The NIR radial velocity
measurements from GIANO - B and IGRINS show an average amplitude of about one
quarter with respect to previously published VIS data, as expected when the RV
jitter is due to stellar activity. Coeval multi-band photometry surprisingly
shows larger amplitudes in the NIR range, explainable with a mixture of cool
and hot spots in the same active region. Conclusions. In this work, the claimed
massive planet around BD+20 1790 is ruled out by our data. We exploited the
crucial role of multi- wavelength spectroscopy when observing young active
stars: thanks to facilities like GIARPS that provide simultaneous observations,
this method can reach its maximum potential.Comment: 12 pages, 7 figure
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