Search results for "Dwarf"
showing 10 items of 136 documents
Stellar structure models in modified theories of gravity: Lessons and challenges
2019
The understanding of stellar structure represents the crossroads of our theories of the nuclear force and the gravitational interaction under the most extreme conditions observably accessible. It provides a powerful probe of the strong field regime of General Relativity, and opens fruitful avenues for the exploration of new gravitational physics. The latter can be captured via modified theories of gravity, which modify the Einstein-Hilbert action of General Relativity and/or some of its principles. These theories typically change the stellar structure equations, thus having a large impact on the astrophysical properties of the corresponding stars and opening a new window to constrain these …
Temperature dependence of sodium and ionized calcium resonance lines perturbed by helium
2014
International audience; Traces of heavy metals in cool DZ white dwarf stars may be attributed to the accretion of circumstellar dust thought to originate from tidal disruption of rocky parent bodies. Spectra of such stars therefore provide a unique opportunity to study the composition of extrasolar planetary systems. The determination of metal abundances from stellar spectra depends on stellar atmospheric parameters and an accurate prior knowledge of the collision broadening of the line profiles by the most common constituents of the stellar atmosphere. For this purpose, we present theoretical absorption spectra of Na and Ca+ broadened by He for the conditions prevailing in cool white dwarf…
The brown dwarf population in the Chamaeleon I cloud
2003
We present the results of a multiband survey for brown dwarfs in the Chamaeleon I dark cloud with the Wide Field Imager (WFI) camera at the ESO/MPG 2.2-m telescope on La Silla (Chile). The survey has revealed a substantial population of brown dwarfs in this southern star forming region. Candidates were selected from R, I and H-alpha imaging observations. We also observed in two medium-band filters, M855 and M915, for the purpose of spectral type determination. The former filter covers a wavelength range containing spectral features characteristic of M-dwarfs, while the latter lies in a relatively featureless wavelength region for these late-type objects. A correlation was found between spec…
Isolated childhood growth hormone deficiency: a 30-year experience on final height and a new prediction model
2022
Purpose We aimed to evaluate the near-final height (nFHt) in a large cohort of pediatricpatients with growth hormone deficiency (GHD) and to elaborate a new predictive method of nFHt. Methods We recruited GHD patients diagnosed between 1987 and 2014 and followed-up until nFHt. To predict the values of nFHt, each predictor was run in a univariable spline. Results We enrolled 1051 patients. Pre-treatment height was -2.43 SDS, lower than parental height (THt) (-1.09 SDS, p < 0.001). The dose of recombinant human GH (rhGH) was 0.21mg/kg/week at start of treatment. nFHt was -1.08 SDS (height gain 1.27 SDS), higher than pre-treatment height (p < 0.001) and comparable to THt. 1.6% of the pat…
Radio emission in ultracool dwarfs: the nearby substellar triple system VHS 1256$-$1257
2018
Aims. With the purpose of investigating the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92-125723.9 (hereafter VHS 1256-1257); this system is composed by an equal-mass M7.5 binary and a L7 low-mass substellar object located at only 15.8 pc. Methods. We observed in phase-reference mode the system VHS 1256-1257 with the Karl G. Jansky Very Large Array at X band and L band and with the European VLBI Network at L band in several epochs during 2015 and 2016. Results. We discovered radio emission at X band spatially coincident with the equal-mass M7.5 binary with a flux density of 60 μJy. We determined a spectral index α …
Accretion disk coronae of intermediate polar cataclysmic variables
2017
Context. Intermediate polar cataclysmic variables (IPCV) contain a magnetic, rotating white dwarf surrounded by a magnetically truncated accretion disk. To explain their strong flickering X-ray emission, accretion has been successfully taken into account. Nevertheless, observations suggest that accretion phenomena might not be the only process behind it. An intense flaring activity occurring on the surface of the disk may generate a corona, contribute to the thermal X-ray emission, and influence the system stability. Aims. Our purposes are: investigating the formation of an extended corona above the accretion disk, due to an intense flaring activity occurring on the disk surface; studying t…
WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome
2018
International audience; Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, ∼70% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like pheno…
Gender-specific soluble α-klotho levels as marker of GH deficiency in children: a case-control study.
2022
Abstract Purpose To evaluate circulating soluble α-klotho (sαKL) levels in GHD children before and after 12 months of GH treatment (GHT). Methods Auxological and basal metabolic parameters, oral glucose tolerance test for glucose and insulin levels, insulin sensitivity indices and klotho levels were evaluated before and after 12 months of follow-up in 58 GHD children and 56 healthy controls. Results At baseline, GHD children showed significantly lower growth velocity standard deviation score (SDS) (p < 0.001), bone/chronological age ratio (p < 0.001), GH peak and area under the curve (AUC) after arginine test (ARG) (both p < 0.001) and glucagon stimulation test (GST) (p < 0.001 …
Adherence to growth hormone (GH) therapy in naïve to treatment GH-deficient children: data of the Italian Cohort from the Easypod Connect Observation…
2019
Background: With the use of non-objective measurement, adherence to growth hormone (GH) therapy has been reported suboptimal in a large proportion of patients, and poor adherence has been shown to affect short-term growth response in patients receiving GH treatment. Objective: The Easypod™ electronic device allows objective measurement of adherence. In this study, we report 3-year prospective adherence data of the Italian cohort of naïve GH deficient (GHD) children extrapolated from the Easypod Connect Observational Study (ECOS) database. Patients and methods: Seventy-three GHD children naïve to GH treatment were included in the analysis. 22 Italian centers participated in the study. Result…
A brief version of the Pediatric Inventory for Parents (PIP) in Spanish population: Stress of main family carers of chronic paediatric patients.
2018
A chronic illness in childhood has a negative impact on the paediatric patient and on family functioning. Psychological stress in parents influences the level of adjustment to the illness of their children. The Pediatric Inventory for Parents (PIP) was designed to measure stress in parents whose child has a chronic illness or requires prolonged medical monitoring. The main objective of this study is to provide a brief version of the Spanish translation of the PIP, across a sample consisting of 465 main familial caregivers (85.2% female, n = 396) between 27 and 67 years old ([Formula: see text] = 44.13; SD = 5.35) of paediatric patients between 9 and 18 years old ([Formula: see text] = 12.10…