3,436 research outputs found
Quiet Sun magnetic fields from space-borne observations: simulating Hinode's case
We examine whether or not it is possible to derive the field strength
distribution of quiet Sun internetwork regions from very high spatial
resolution polarimetric observations in the visible. In particular, we consider
the case of the spectropolarimeter attached to the Solar Optical Telescope
aboard Hinode. Radiative magneto-convection simulations are used to synthesize
the four Stokes profiles of the \ion{Fe}{1} 630.2 nm lines. Once the profiles
are degraded to a spatial resolution of 0\farcs32 and added noise, we infer the
atmospheric parameters by means of Milne-Eddington inversions. The comparison
of the derived values with the real ones indicates that the visible lines yield
correct internetwork field strengths and magnetic fluxes, with uncertainties
smaller than 150 G, when a stray light contamination factor is included
in the inversion. Contrary to the results of ground-based observations at
1\arcsec, weak fields are retrieved wherever the field is weak in the
simulation.Comment: Accepted for publication in ApJ Letter
A super-Earth orbiting the nearby M-dwarf GJ 536
We report the discovery of a super-Earth orbiting the star GJ 536 based on
the analysis of the radial-velocity time series from the HARPS and HARPS-N
spectrographs. GJ 536 b is a planet with a minimum mass M sin of 5.36 +-
0.69 Me with an orbital period of 8.7076 +- 0.0025 days at a distance of
0.066610(13) AU, and an orbit that is consistent with circular. The host star
is the moderately quiet M1 V star GJ 536, located at 10 pc from the Sun. We
find the presence of a second signal at 43 days that we relate to stellar
rotation after analysing the time series of Ca II H&K and H alpha spectroscopic
indicators and photometric data from the ASAS archive. We find no evidence
linking the short period signal to any activity proxy. We also tentatively
derived a stellar magnetic cycle of less than 3 years.Comment: 14 pages, 14 figures, 5 tables, Accepted in A&
The RoPES project with HARPS and HARPS-N. I. A system of super-Earths orbiting the moderately active K-dwarf HD 176986
We report the discovery of a system of two super-Earths orbiting the
moderately active K-dwarf HD 176986. This work is part of the RoPES RV program
of G- and K-type stars, which combines radial velocities (RVs) from the HARPS
and HARPS-N spectrographs to search for short-period terrestrial planets. HD
176986 b and c are super-Earth planets with masses of 5.74 and 9.18
M, orbital periods of 6.49 and 16.82 days, and distances of 0.063
and 0.119 AU in orbits that are consistent with circular. The host star is a
K2.5 dwarf, and despite its modest level of chromospheric activity (log(R'hk) =
- 4.90 +- 0.04), it shows a complex activity pattern. Along with the discovery
of the planets, we study the magnetic cycle and rotation of the star. HD 176986
proves to be suitable for testing the available RV analysis technique and
further our understanding of stellar activity.Comment: 21 pages, 24 figures, 7 table
Semantic variant primary progressive aphasia: Practical recommendations for treatment from 20 years of behavioural research
People with semantic variant primary progressive aphasia (svPPA) present with a char-acteristic progressive breakdown of semantic knowledge. There are currently no pharmacological interventions to cure or slow svPPA, but promising behavioural approaches are increasingly reported. This article offers an overview of the last two decades of research into interventions to support language in people with svPPA including recommendations for clinical practice and future research based on the best available evidence. We offer a lay summary in English, Spanish and French for education and dissemination purposes. This paper discusses the implications of right-versus left-predominant atrophy in svPPA, which naming therapies offer the best outcomes and how to capitalise on preserved long-term memory systems. Current knowledge regarding the maintenance and generalisation of language therapy gains is described in detail along with the development of compensatory approaches and educational and support group programmes. It is concluded that there is evidence to support an integrative framework of treatment and care as best practice for svPPA. Such an approach should combine rehabilitation interventions addressing the language impairment, compensatory approaches to support activities of daily living and provision of education and support within the context of dementia
Preparing the COROT space mission: new variable stars in the galactic Anticenter direction
The activities related to the preparation of the asteroseismic, photometric
space mission COROT are described. Photoelectric observations, wide--field CCD
photometry, uvbyB calibrations and further time--series have been obtained at
different observatories and telescopes. They have been planned to complete the
COROT programme in the direction of the galactic Anticenter. In addition to
suitable asteroseismic targets covering the different evolutionary stages
between ZAMS and TAMS, we discovered several other variable stars, both
pulsating and geometrical. We compared results on the incidence of variability
in the galactic Center and Anticenter directions. Physical parameters have been
obtained and evolutionary tracks fitting them have been calculated. The
peculiarities of some individual stars alre pointed out. Paper based on
observations collected at the San Pedro Martir, Sierra Nevada, Teide, La Silla,
Haute-Provence and Roque de Los Muchachos (Telescopio Nazionale Galileo and
Mercator telescopes) observatories.Comment: 13 pages, 9 figures. Accepted for The Astronomical Journal (2005 May
volume
Topological Analysis of Metabolic Networks Integrating Co-Segregating Transcriptomes and Metabolomes in Type 2 Diabetic Rat Congenic Series
Background: The genetic regulation of metabolic phenotypes (i.e., metabotypes) in type 2 diabetes mellitus is caused by complex organ-specific cellular mechanisms contributing to impaired insulin secretion and insulin resistance. Methods: We used systematic metabotyping by 1H NMR spectroscopy and genome-wide gene expression in white adipose tissue to map molecular phenotypes to genomic blocks associated with obesity and insulin secretion in a series of rat congenic strains derived from spontaneously diabetic Goto-Kakizaki (GK) and normoglycemic Brown-Norway (BN) rats. We implemented a network biology strategy approach to visualise shortest paths between metabolites and genes significantly associated with each genomic block. Results: Despite strong genomic similarities (95-99%) among congenics, each strain exhibited specific patterns of gene expression and metabotypes, reflecting metabolic consequences of series of linked genetic polymorphisms in the congenic intervals. We subsequently used the congenic panel to map quantitative trait loci underlying specific metabotypes (mQTL) and genome-wide expression traits (eQTL). Variation in key metabolites like glucose, succinate, lactate or 3-hydroxybutyrate, and second messenger precursors like inositol was associated with several independent genomic intervals, indicating functional redundancy in these regions. To navigate through the complexity of these association networks we mapped candidate genes and metabolites onto metabolic pathways and implemented a shortest path strategy to highlight potential mechanistic links between metabolites and transcripts at colocalized mQTLs and eQTLs. Minimizing shortest path length drove prioritization of biological validations by gene silencing. Conclusions: These results underline the importance of network-based integration of multilevel systems genetics datasets to improve understanding of the genetic architecture of metabotype and transcriptomic regulations and to characterize novel functional roles for genes determining tissue-specific metabolism
EQ-5D-5L Health-State Values for the Mexican Population.
OBJECTIVE: To generate a value set for the Mexican adult general population to support and facilitate the inclusion of quality-adjusted life years (QALYs) into the health technology assessment process of the Mexican healthcare authorities. METHODS: A representative sample of the Mexican adult population stratified by age, sex and socio-economic status was used. Following version 2.0 of the EuroQol EQ-5D-5L valuation protocol, trained interviewers guided participants in completing composite time trade-off (cTTO) and discrete-choice experiment (DCE) tasks included in the EQ-VT software. Generalized least squares, Tobit and Bayesian models were used for cTTO data. The choice of value set model was based on criteria that included: theoretical considerations, parsimony, logical ordering of coefficients, and statistical significance. RESULTS: Based on quality control criteria and interviewer judgment, 1000 out of 1032 participants provided useable responses. Participants' demographic characteristics were similar to the 2010 Mexican Population Census and followed the socioeconomic structure defined by the Mexican Association of Marketing Research and Public Opinion Agencies (AMAI). The predicted index values in the final cTTO model (a heteroscedastic censored model with Bayesian estimation) ranged from - 0.5960 to 1, with 19.7% of all predicted health state scores less than 0 (i.e., worse than dead). CONCLUSION: This study has generated the first value set representing the stated preferences of the Mexican adult population for use in estimating QALYs. The resulting EQ-5D-5L value set is technically robust and will facilitate health economic analyses as well as quality-of-life studies
Assessing the relationship between markers of glycemic control through flexible copula regression models
Glycated haemoglobin (HbA1c) is a sensitive marker of blood glucose in patients with diabetes. However, levels can vary considerably, even amongst individuals with similar mean blood glucose concentrations. Other glycated proteins, such as fructosamine, can also act as blood sugar markers, but estimating HbA1c and fructosamine via independent models may lead to errors of interpretation regarding disease severity. From a clinical standpoint, it would be of great interest to know the factors that affect the mean concentration of both HbA1c and fructosamine, which influence the variability in the concentrations of these glycated markers and cause HbA1c/fructosamine discordance. Flexible models are required to illustrate the behaviour of these variables as well as the association between them. This work reviews existing models that might serve in this regard. Flexible copula regression models using splines were used to provide a better understanding of the behaviour of both glycated proteins and the relationship between them under the possible influence of different covariates. This work shows the usefulness of this type of models in practise and provides a basis for their clinical interpretation by means of an understandable case study. Ultimately, to better understand the effects of each continuous covariate, they are represented at the true scale of the response variables
Language and cultural capital in school experience of Polish children in Scotland
This article addresses the complex relationship between migration and education in the context of recent intra-European labour mobility. It considers how this mobility impacts the education and life chances of migrant students attending schools in Scotland, UK. By examining the experiences of Polish migrant children and youth at schools in Scotland, the article engages with the issues of language, cultural capital transferability and social positioning. Drawing on qualitative data from 65 in-depth interviews with school children aged 5–17 years, their parents and teachers, as well as observations in the contexts of school and home, the article points to a range of factors affecting the transition of migrant pupils to new schools and social environments
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Assessing the relationship between markers of glycemic control through flexible copula regression models
Glycated haemoglobin (HbA1c) is a sensitive marker of blood glucose in patientswith diabetes. However, levels can vary considerably, even among individualswith similar mean blood glucose concentrations. Other glycated proteins, such asfructosamine, can also act as blood sugar markers, but estimating HbA1c and fruc-tosamine via independent models may lead to errors of interpretation regardingdisease severity. From a clinical standpoint, it would be of great interest to knowthe factors that affect the mean concentration of both HbA1c and fructosamine,that influence the variability in the concentrations of these glycated markers, andthat cause HbA1c/fructosamine discordance. Flexible models are required that illus-trate the behaviour of these variables as well as the association between them. Thepresent work reviews existing models that might serve in this regard. Flexible cop-ula regression models using P-splines, were used to provide a better understandingof the behaviour of both glycated proteins, and the relationship between them underthe possible influence of different covariates. This work shows the usefulness ofthis type of models in practice, and provides a basis for its clinical interpretation bymeans of an understandable case study. Ultimately, to better understand the effectsof each continuous covariate, they were represented at the true scale of the response variables
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