51 research outputs found
The VMC Survey - XIII : Type II Cepheids in the Large Magellanic Cloud
Date of Acceptance: 27/10/2014The VISTA (Visible and Infrared Survey Telescope for Astronomy) survey of the Magellanic Clouds System (VMC) is collecting deep Ks-band time-series photometry of the pulsating variable stars hosted in the system formed by the two Magellanic Clouds and the Bridge connecting them. In this paper, we have analysed a sample of 130 Large Magellanic Cloud (LMC) Type II Cepheids (T2CEPs) found in tiles with complete or near-complete VMC observations for which identification and optical magnitudes were obtained from the OGLE III (Optical Gravitational Lensing Experiment) survey. We present J and Ks light curves for all 130 pulsators, including 41 BL Her, 62 W Vir (12 pW Vir) and 27 RV Tau variables. We complement our near-infrared photometry with the V magnitudes from the OGLE III survey, allowing us to build a variety of period-luminosity (PL), period-luminosity-colour (PLC) and period-Wesenheit (PW) relationships, including any combination of the V, J, Ks filters and valid for BL Her and W Vir classes. These relationships were calibrated in terms of the LMC distance modulus, while an independent absolute calibration of the PL(Ks) and the PW(Ks, V) was derived on the basis of distances obtained from Hubble Space Telescope parallaxes and Baade-Wesselink technique. When applied to the LMC and to the Galactic globular clusters hosting T2CEPs, these relations seem to show that (1) the two Population II standard candles RR Lyrae and T2CEPs give results in excellent agreement with each other; (2) there is a discrepancy of ~0.1 mag between Population II standard candles and classical Cepheids when the distances are gauged in a similar way for all the quoted pulsators. However, given the uncertainties, this discrepancy is within the formal 1Ï uncertainties.Peer reviewedFinal Accepted Versio
The VMC survey - XIV : First results on the look-back time star formation rate tomography of the Small Magellanic Cloud
Date of Acceptance: 20/01/2015We analyse deep images from the VISTA survey of the Magellanic Clouds in the YJKs filters, covering 14 deg2 (10 tiles), split into 120 subregions, and comprising the main body and Wing of the Small Magellanic Cloud (SMC). We apply a colour-magnitude diagram reconstruction method that returns their best-fitting star formation rate SFR(t), age-metallicity relation (AMR), distance and mean reddening, together with 68 per cent confidence intervals. The distance data can be approximated by a plane tilted in the East-West direction with a mean inclination of 39°, although deviations of up to ±3 kpc suggest a distorted and warped disc. After assigning to every observed star a probability of belonging to a given age-metallicity interval, we build high-resolution population maps. These dramatically reveal the flocculent nature of the young star-forming regions and the nearly smooth features traced by older stellar generations. They document the formation of the SMC Wing at ages <0.2 Gyr and the peak of star formation in the SMC Bar at ~40 Myr. We clearly detect periods of enhanced star formation at 1.5 and 5 Gyr. The former is possibly related to a new feature found in the AMR, which suggests ingestion of metal-poor gas at ages slightly larger than 1 Gyr. The latter constitutes a major period of stellar mass formation. We confirm that the SFR(t) was moderately low at even older ages.Peer reviewe
The Hubble Catalog of Variables
We aim to construct an exceptionally deep (V ~< 27) catalog of variable
objects in selected Galactic and extragalactic fields visited multiple times by
the Hubble Space Telescope (HST). While HST observations of some of these
fields were searched for specific types of variables before (most notably, the
extragalactic Cepheids), we attempt a systematic study of the population of
variable objects of all types at the magnitude range not easily accessible with
ground-based telescopes. The variability timescales that can be probed range
from hours to years depending on how often a particular field has been visited.
For source extraction and cross-matching of sources between visits we rely on
the Hubble Source Catalog which includes 10^7 objects detected with WFPC2, ACS,
and WFC3 HST instruments. The lightcurves extracted from the HSC are corrected
for systematic effects by applying local zero-point corrections and are
screened for bad measurements. For each lightcurve we compute variability
indices sensitive to a broad range of variability types. The indices
characterize the overall lightcurve scatter and smoothness. Candidate variables
are selected as having variability index values significantly higher than
expected for objects of similar brightness in the given set of observations.
The Hubble Catalog of Variables will be released in 2018.Comment: 5 pages, 3 figures, 1 table, proceedings of the 22nd Los Alamos
Stellar Pulsation Conference "Wide-field variability surveys: a 21st-century
perspective" held in San Pedro de Atacama, Chile, Nov. 28-Dec. 2, 201
Phylogenomic analysis of a 55.1 kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani Species Complex
Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-userÂżs needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option availabl
TRY plant trait database â enhanced coverage and open access
Plant traitsâthe morphological, anatomical, physiological, biochemical and phenological characteristics of plantsâdetermine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of traitâbased plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traitsâalmost complete coverage for âplant growth formâ. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and traitâenvironmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.
BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362
The structure of the Large Magellanic Cloud from hot binary stars and Classical Cepheids
We present the results of analysis of 1764 eclipsing binary stars (EBs) in the Large Magellanic Cloud (LMC) contaminating the sample of candidate Classical Cepheids (CCs) from the EROS-2 survey. These binaries have the same periods and luminosities as Classical Cepheids, but their colors are bluer. These EBs contain hot massive Main Sequence components and could be used as tracers of regions of recent star formation activity
CHELT therapy in the treatment of chronic insertional Achilles tendinopathy.
The application of laser therapy on soft tissue is used for pain relief, anti-inflammation action and biostimulation. The efficiency of High Energy Laser Therapy has not yet been studied on Achilles tendinopathy. The aim of the study is to evaluate the effectiveness of a flow of Cold air and High Energy Laser Therapy (CHELT) versus Extracorporeal Shock Waves Therapy (ESWT) in the treatment of Achilles tendinopathy. In this prospective, clinical trial, 60 subjects affected by insertional Achilles tendinopathy were enrolled and randomized to CHELT (30 subjects) or to ESWT (30 subjects). In CHELT group the patients received ten daily sessions of 1,200 J and 12 W of laser therapy (wavelength of 1,084, 810 and 980 nm) added to a flow of cold air at â30 °C. In the ESWT group, the patients received three sessions at 3- to 4-day intervals of 1,600 impulses with an energy flux density (EFD) of 0.05â0.07 mJ/mm2. Both groups of participants performed stretching and eccentric exercises over a 2-month period. The visual analogue scale (VAS), the AnkleâHindfoot Scale, and the Roles and Maudsley Score were measured before treatment (T0), and at end of the treatment session (T1) and 2 (T2) and 6 months (T3) after treatment during the follow-up examinations. In both groups, we found a statistically significant improvement of the VAS at T1, T2 and T3 (pâ<â0.01). The difference between the two groups was statistically significant in favour of the CHELT group (pâ<â0.001). At 2 months, the CHELT group was statistically better for AnkleâHindfoot Scale and the Roles and Maudsley Score (pâ<â0.05) and at 6 months only for the Roles and Maudsley Score (pâ<â0.001). High Energy Laser Therapy gave quicker and better pain relief. It also gave the patient a full functional recovery and greater satisfaction
Variability search in M31 using principal component analysis and the Hubble Source Catalogue
Principal component analysis (PCA) is being extensively used in Astronomy but not yet exhaustively exploited for variability search. The aim of this work is to investigate the effectiveness of using the PCA as a method to search for variable stars in large photometric data sets. We apply PCA to variability indices computed for light curves of 18 152 stars in three fields inM31 extracted from the Hubble Source Catalogue. The projection of the data into the principal components is used as a stellar variability detection and classification tool, capable of distinguishing between RR Lyrae stars, long-period variables (LPVs) and non-variables. This projection recovered more than 90 per cent of the known variables and revealed 38 previously unknown variable stars (about 30 per cent more), all LPVs except for one object of uncertain variability type.We conclude that this methodology can indeed successfully identify candidate variable stars. © 2017 The Authors
- âŠ