bluuebunny/crossref_metadata_2025_split huggingface dataset:
NGC 2587: a sparse open cluster projected onto a populous star field
Authors: Piatti Andrés E. , Clariá Juan J. , Ahumada Andrea V. 
Published: January 2010

AbstractWe present CCD BVIKC photometry in the field of the open cluster NGC 2587. We developed a new method to clean statistically the colour–magnitude diagrams. NGC 2587 is found to be slightly younger than the Hyades and probably of solar metallicity. From 18 probable members with measured proper motions, we derived the following mean cluster values: μα = −4.3 ± 3.6 mas yr−1 and μδ = −2.5 ± 3.4 mas yr−1. Colour excesses, E(B − V) = 0.10 and E(V − I) = 0.15 mag, and a heliocentric distance of 3.7 ± 0.7 kpc are obtained. The interstellar extinction in the cluster direction is found to follow the normal reddening law.
Hα imaging of X-ray sources in selected globular clusters with SOAR
Authors: Pietrukowicz Pawel 
Published: January 2010

AbstractI present results of a search for cataclysmic variables (CVs) and chromospherically active binaries (ABs) as counterparts to X-ray sources detected with Chandra in six Galactic globular clusters (GCs): M 4, M 28, M 30, M 71, M 80, and NGC 6752. Binary systems play a critical role in the evolution of GCs, serving as an internal energy source countering the tendency of GC cores to collapse. Theoretical studies predict dozens of CVs in the cores of some GCs (e.g., 130 for M 28, 40 for M 30). A number of such binaries are also expected outside the core radius. However, few CVs are known so far in GCs. Using the 4.1m SOAR telescope, I have found 25 stars with Hα excess in the observed clusters. Six are candidate CVs, five are candidate active binaries. The other 14 objects with Hα excess are probably foreground/background stars or extragalactic sources.
The population of young stars in Orion A: X-rays and IR properties
Authors: Pillitteri Ignazio , Wolk S. J. , Allen L. , Megeath S. T. , Gutermuth R. A. ,   the soxs collaboration
Published: January 2010

AbstractStars in the very early stages of their formation are characterized by strong infrared excess and X-ray emission. We present the results of the survey of Orion A in both the infrared and X-rays obtained with the Spitzer and XMM/Newton observatories. We study the spectral-energy distribution class of the young stellar object (YSO) population using infrared colors from 2mass and Spitzer (IRAC and MIPS) and by means of X-ray fluxes, luminosities and plasma temperatures. We discuss clustering properties and spatial segregation among different infrared YSO classes to trace their formation history.
Clusters and stellar angular-momentum evolution
Authors: Pinsonneault M. H. , Terndrup D. M. , Denisenkov P. 
Published: January 2010

AbstractThe origin and evolution of stellar rotation has proven to be both important and challenging. Data obtained in star clusters has already provided key constraints on the role of protostellar disks and the timescales for angular-momentum loss and internal transport. Recent data sets also provide empirical support for the idea that a wide range of rotation rates converge on the main sequence. We evaluate the prospects for rotation–mass–age relationships and the role of open clusters in calibrating them.
Extragalactic star-forming regions and open clusters in the Milky Way
Authors: Sakhibov F. , Gusev A. S. , Kharchenko N. V. , Piskunov A. E. 
Published: January 2010

AbstractWe have carried out a comparative analysis of the evolution of integrated photometric parameters of young star-forming complexes in spiral and irregular galaxies and Galactic open clusters. We find that when the interstellar extinction is properly taken into account, the extragalactic complexes observed as giant Hii regions and open clusters in the Milky Way form a single evolutionary sequence of objects evolving at different stages.
The spatial distribution of stars in open clusters
Authors: Sánchez Néstor , Alfaro Emilio J. 
Published: January 2010

AbstractWe study the internal spatial structure of 16 open clusters in the Milky Way spanning a wide range of ages. For this, we use the minimum-spanning-tree method (the Q parameter, which enables one to classify the stellar distribution as either radially or fractally clustered), King-profile fitting, and the correlation dimension (Dc) for those clusters with fractal patterns. On average, clusters with fractal-like structure are younger than those exhibiting radial stellar-density profiles. There is a significant correlation between Q and the cluster age measured in crossing-time units. For fractal clusters, there is a significant correlation between fractal dimension and age. These results support the idea that stars in newly born clusters likely follow the fractal patterns of their parent molecular clouds, and eventually evolve towards more centrally concentrated structures. However, stellar clusters as old as ~ 100 Myr can exist that have not totally destroyed their fractal structure. Finally, we have found the intriguing result that the lowest fractal dimensions obtained for the open clusters seem to be considerably smaller than the average value measured in Galactic molecular cloud complexes.
Refining the true parameters of the open cluster NGC 4852
Authors: Solivella Gladys , Giorg Edgard , Vázquez Rubén , Carraro Giovanni 
Published: January 2010

AbstractNGC 4852 is a moderately compact cluster centered at α2000 = 13 : 00 : 09; δ = −59 : 36 : 48, located near the center of an Hα superring. This cluster forms part of an extended region including young stellar aggregates inside a circle with a radius of 3 degrees, where many show an abundance of emission line stars. In the field of this cluster, two stars of known type exist: Wray 15–1039 (emission-line object) and CD −58:4845 (emission-line star). We do not yet know whether the Be phase is transient or whether it is just what randomly happens in some hot stars. It appears that Be star may be found even in clusters as old as 70 Myr with a high occurrence rate in clusters of 25–27 Myr old. A recent photometric survey in NGC 4852 down to V = 22 – 23 mag established that NGC 4852 is about 200 – 250 Myr old, located at 1.1 kpc from the Sun and with a mean E(B − V) = 0.45 mag. Since the presence of potential Be-type stars in the cluster area suggests it may be a very young object instead of moderately old, we decided to carry out spectroscopy for 33 selected stars and CCD UBVI photometry for the bright objects in the cluster area. This way, we attempt to clarify their evolutionary state and include them in the framework of emission-line stars and open clusters. From our analysis, we agree with the cluster distance and reddening determined by earlier studies, but we derive that the age of NGC 4852 is younger than 40 Myr.
Membership status of TWA22AB
Authors: Teixeira Ramachrisna , Ducourant Christine , Chauvin Gael , Krone–Martins Alberto G. O. , Bonnefoy Mickael , Song Inseok 
Published: January 2010

AbstractUsing the ESO NTT/SUSI2 telescope, we observed TWA22AB during five different observing runs over 1.2 years to measure its trigonometric parallax and proper motion. HARPS at the ESO 3.6m telescope was also used to measure the system's radial velocity over 2 years. Based on trigonometric-parallax, proper-motion and radial-velocity measurements, we re-analyzed the membership of TWA22AB of the young, nearby associations TW Hydrae, β Pictoris and Tucana–Horologium.
sacy: open clusters connected to young nearby associations
Authors: Torres C. A. O. , Quast G. R. , Melo C. H. F. , Sterzik M. , de la Reza R. , da Silva Licio 
Published: January 2010

AbstractIn recent years. we have spectroscopically observed thousands of counterparts of selected ROSAT bright sources in the sacy project (Search for Associations Containing Young stars). We demonstrated that hundreds of the young stars found this way belong to nearby young, loose associations, some detected only in sacy, with ages in the range from 5 to 100 Myr. For their ages, these associations show no trace of their primitive nurseries, which poses some difficulties as to their origins. Nevertheless, there are some associations clearly associated with young open clusters, such as the ϵ Cha association (6 Myr) with the η Cha cluster, and the Argus association with IC 2391 (40 Myr). There seem to exist also more subtle connections, such as the AB Dor association (75 Myr) with the Pleiades. Here, we present evidence of the connections of young associations to open clusters, to understand their origin and their possible insertion in the cluster infant-mortality and Gould Belt scenarios.
Probing star formation at intermediate z
Authors: Voyer E. N. , de Mello D. F. , Quirk C. , Siana B. , Gardner J. P. , Teplitz H. 
Published: January 2010

AbstractWe summarize the latest results of an ongoing project aimed at connecting starburst galaxies in the local Universe and Lyman-break galaxies (LBGs) in the distant Universe using rest-frame ultraviolet (UV) images. We are quantifying star formation in the local Universe using GALEX data of interacting galaxies and we are using Hubble Space TelescopeU-band and optical images of the Ultra Deep Field to quantify star formation at intermediate (z ~ 1) and high (z > 2) redshifts, respectively. We are measuring sizes of star-forming clumps in all redshift ranges and searching for evolutionary effects. We chose the rest-frame UV to do this work because young and massive stars radiate most their energy in the UV and also because LBGs are selected to be UV-bright. We discuss whether all galaxies go through an LBG phase and whether disks show any sign of size of evolution at z < 1.
Super star clusters and their emission lines
Authors: Wünsch Richard , Palouš Jan , Tenorio–Tagle Guillermo , Silich Sergiy , Muñoz–Tuñón Casiana 
Published: January 2010

AbstractSuper star clusters (SSCs) are young massive objects typically observed in starburst galaxies. They consist of millions of stars occupying volumes only several parsecs across. Recent infrared observations of SSCs reveal strong emission lines with moderately supersonic widths (FWHM ~ 50 – 100 km s−1). An additional, much broader and weaker line component is present in some cases. Using 2D and 3D hydrodynamic simulations, we study models of SSCs in the so-called bimodal regime, which occurs if the stellar density inside the cluster exceeds a certain limit. We confirm the existence of the bimodal solution predicted analytically and suggest an explanation for double-component line profiles: the narrow component is formed close to the cluster center by repressurizing shocks compressing the rarefied gas cooled down due to the thermal instability into dense cold clumps, while the broad component is created by the wind, which cools down at a certain distance from the cluster.
Blue stragglers in star clusters and the conventional SSP models
Authors: Xin Yu , de Grijs Richard , Deng Licai , Kroupa Pavel 
Published: January 2010

AbstractThe presence of blue straggler stars (BSs) as secure members of star clusters poses a major challenge to the conventional picture of simple stellar population (SSP) models. The models are based on the stellar evolution theory of single stars, while the major formation mechanisms of BSs are all correlated with stellar interactions. Based on a sufficient working sample including 100 Galactic open clusters, one Galactic globular cluster, and seven Magellanic Cloud star clusters, we discuss the modifications of the properties of broad-band colors and Lick indices of the standard SSP models due to BS populations.
IC 361, a distant intermediate-age cluster in Camelopardalis
Authors: Zdanavičius Justas , Boyle Richard P. , Vrba Frederick J. , Zdanavičius Kazimieras , Bartašiūtė Stanislava 
Published: January 2010

AbstractWe have undertaken CCD photometry in the eight-color Vilnius + I system for the open cluster IC 361 (l = 147.5°, b = 5.7°) located in the constellation of Camelopardalis. Based on multicolor data, estimates of distance moduli, foreground reddening and metallicity have been obtained for individual stars measured in the field of the cluster. This allowed us to eliminate most of the field stars and to identify the probable cluster members, from which we derived the true distance modulus (m − M)0 = 12.7 mag and metallicity [Fe/H] = −0.3 dex. The interstellar extinction is found to be nonuniform across the field, with values of AV ranging from 1.9 to 2.6 mag. A comparison of the color–magnitude diagrams with Padova isochrones yields (m − M)0 = 12.6 mag, or a cluster distance of 3.3 kpc, and an age of 1.0 Gyr. Therefore, IC 361 appears to be a mildly metal-deficient cluster of intermediate age, located as far as, or just beyond, the Perseus spiral arm.
The globular cluster NGC 5286: color–magnitude diagram and variable stars
Authors: Zorotovic M. , Catelan M. , Zoccali M. , Smith H. A. , Pritzl B. J. 
Published: January 2010

AbstractWe present BV photometry and the results of a search for stellar variability in the globular cluster NGC 5286, which has tentatively been associated with the Canis Major dwarf spheroidal galaxy. Our results indicate an Oosterhoff type II for the cluster, which is unusual for an object of extragalactic origin.
An RF spectrometer for fast wide band measurement
Authors: Hemour Simon , Podevin Florence , Xavier Pascal 
Published: January 2010

A new type of spectrum analyzer using RF interferometry is presented. The stationary wave integrated Fourier transform spectrometer is dedicated to the measurement of transient wideband signals. The spectrometer is mobile and cheap. It consists of spatial samplers placed along a waveguide ended by a short circuit. The standing wave caused by the short circuit is sampled and the spectrum is obtained by an FFT computation. A 0.3–5 GHz analyzer was built as a proof-of-principle demonstration and an application to RF dosimetry is shown.
Intracellular aggregation of human stefin B: confocal and electron microscopy study
Authors: Čeru Slavko , Layfield Robert , Zavašnik‐Bergant Tina , Repnik Urška , Kopitar‐Jerala Nataša , Turk Vito , Žerovnik Eva 
Published: January 2010

Background. Protein aggregation is a major contributor to the pathogenic mechanisms of human neurodegenerative diseases. Mutations in the CSTB (cystatin B) gene [StB (stefin B)] cause EPM1 (progressive myoclonus epilepsy of type 1), an epilepsy syndrome with features of neurodegeneration and increased oxidative stress. Oligomerization and aggregation of StB in mammalian cells have recently been reported. It has also been observed that StB is overexpressed after seizures and in certain neurodegenerative conditions, which could potentially lead to its aggregation. Human StB proved to be a good model system to study amyloid fibril formation in vitro and, as we show here, to study protein aggregation in cells.Results. Endogenous human StB formed smaller, occasional cytoplasmic aggregates and chemical inhibition of the UPS (ubiquitin–proteasome system) led to an increase in the amount of the endogenous protein and also increased its aggregation. Further, we characterized both the untagged and T‐Sapphire‐tagged StB on overexpression in mammalian cells. Compared with wild‐type StB, the EPM1 missense mutant (G4R), the aggregate‐prone EPM1 mutant (R68X) and the Y31 StB variant (both tagged and untagged) formed larger cytosolic and often perinuclear aggregates accompanied by cytoskeletal reorganization. Non‐homogeneous morphology of these large aggregates was revealed using TEM (transmission electron microscopy) with StB detected by immunogold labelling. StB‐positive cytoplasmic aggregates were partially co‐localized with ubiquitin, proteasome subunits S20 and S26 and components of microfilament and microtubular cytoskeleton using confocal microscopy. StB aggregates also co‐localized with LC3 and the protein adaptor p62, markers of autophagy. Flow cytometry showed that protein aggregation was associated with reduced cell viability.Conclusions. We have shown that endogenous StB aggregates within cells, and that aggregation is increased upon protein overexpression or proteasome inhibition. From confocal and TEM analyses, we conclude that aggregates of StB show some of the molecular characteristics of aggresomes and may be eliminated from the cell by autophagy. Intracellular StB aggregation shows a negative correlation with cell survival.
Angiotensin II infusion promotes ascending aortic aneurysms: attenuation by CCR2 deficiency in apoE−/− mice
Authors: Daugherty Alan , Rateri Debra L. , Charo Israel F. , Owens A. Phillip , Howatt Deborah A. , Cassis Lisa A. 
Published: January 2010

AngII (angiotensin II) induces atherosclerosis and AAAs (abdominal aortic aneurysms) through multiple proposed mechanisms, including chemotaxis. Therefore, we determined the effects of whole-body deficiency of the chemokine receptor CCR2 (CC chemokine receptor 2) on these diseases. To meet this objective, apoE (apolipoprotein E)−/− mice that were either CCR2+/+ or CCR2−/−, were infused with either saline or AngII (1000 ng·kg−1 of body weight·min−1) for 28 days via mini-osmotic pumps. Deficiency of CCR2 markedly attenuated both atherosclerosis and AAAs, unrelated to systolic blood pressure or plasma cholesterol concentrations. During the course of the present study, we also observed that AngII infusion led to large dilatations that were restricted to the ascending aortic region of apoE−/− mice. The aortic media in most of the dilated area was thickened. In regions of medial thickening, distinct elastin layers were discernable. There was an expansion of the distance between elastin layers in a gradient from the intimal to the adventitial aspect of the media. This pathology differed in a circumscribed area of the anterior region of ascending aortas in which elastin breaks were focal and almost transmural. All regions of the ascending aorta of AngII-infused mice had diffuse medial macrophage accumulation. Deficiency of CCR2 greatly attenuated the AngII-induced lumen dilatation in the ascending aorta. This new model of ascending aortic aneurysms has pathology that differs markedly from AngII-induced atherosclerosis or AAAs, but all vascular pathologies were attenuated by CCR2 deficiency.
Prevalence and natural history of heart disease in adults with primary mitochondrial respiratory chain disease
Authors: Limongelli Giuseppe , Tome‐Esteban Maite , Dejthevaporn Charungthai , Rahman Shamima , Hanna Michael G. , Elliott Perry M. 
Published: January 2010

AimsThe prevalence and natural history of cardiovascular disease in adult patients with respiratory chain disease (RCD) is poorly characterized. We sought to determine the frequency and natural history of cardiac disease in patients with primary RCD.Methods and resultsThirty‐two patients (37.8 ± 12.6 years) with a definite diagnosis of RCD underwent clinical examination, electrocardiography (ECG), 24 h Holter ECG, and cardiopulmonary exercise testing. Patients were classified into six different phenotypes: mitochondrial myopathy (MM; n = 8), chronic progressive ophthalmoplegia (CPEO; n = 2), chronic progressive ophthalmoplegia with myopathy (CPEO + MM; n = 12), Kearns–Sayre syndrome (KSS; n = 2), mitochondrial encephalopathy with lactic acidosis and stroke‐like episodes (MELAS; n = 7), neuropathy, ataxia, and retinitis pigmentosa (NARP; n = 1). Twenty‐two patients (69%) had a mitochondrial DNA mutation. Twenty‐six patients (81%) had evidence for cardiac involvement: ECG abnormalities (69%) and cardiomyopathy (hypertrophic 19%; restrictive 3%; left ventricular non‐compaction 3%). During follow‐up (4.1 ± 2.8 years), two patients with CPEO + MM developed hypertrophic cardiomyopathy and one patient with NARP developed peripartum dilated cardiomyopathy. Four patients (KSS = 2; MM = 1; MELAS = 1) developed arrhythmias or syncope requiring device therapy or invasive procedures. One patient with MM and cardiomyopathy had an orthotopic heart transplant. One patient with CPEO + MM died from respiratory failure. Freedom from all cardiovascular events at 5 years was 67% (95% CI 47.4–86.6).ConclusionAll patients with RCD should undergo careful and repeated clinical assessment to diagnose and manage cardiovascular involvement. However, life‐threatening cardiovascular complications rarely occur, and the prognosis is generally favourable.
Functional effects of glucose transporters in human ventricular myocardium
Authors: von Lewinski Dirk , Gasser Robert , Rainer Peter P. , Huber Marie‐Sophie , Wilhelm Bastian , Roessl Ulrich , Haas Tobias , Wasler Andrae , Grimm Michael , Bisping Egbert , Pieske Burkert 
Published: January 2010

AimsInsulin‐dependent positive inotropic effects (PIE) are partially Ca2+ independent. This mechanism is potentially glucose dependent. In contrast to most animal species, human myocardium expresses high levels of sodium‐glucose‐transporter‐1 (SGLT‐1) mRNA besides the common glucose‐transporters‐1 and ‐4 (GLUT1, GLUT4).Methods and resultsWe used ventricular myocardium from 61 end‐stage failing human hearts (ischaemic cardiomyopathy, ICM and dilated cardiomyopathy, DCM) and 13 non‐failing donor hearts. The effect of insulin on isometric twitch force was examined with or without blocking of PI3‐kinase, GLUT4‐translocation, or SGLT‐1. Substrate‐dependent (glucose vs. pyruvate vs. palmitoyl‐carnitine) effects were tested in atrial myocardium. mRNA expression of glucose transporters was analysed. Insulin increased developed force by 122 ± 7.4, 121.7 ± 2.5, and 134.1 ± 5.7% in non‐failing, DCM, and ICM (P < 0.05 vs. DCM), respectively. Positive inotropic effect was partially blunted by inhibition of PI‐3‐kinase, GLUT4, or SGLT1. Combined inhibition of PI3‐kinase and glucose‐transport completely abolished PIE. Positive inotropic effect was significantly stronger in glucose‐containing solution compared with pyruvate or palmitoyl‐carnitine containing. mRNA expression showed only a tendency towards elevated GLUT4‐expression in ICM.ConclusionsPositive inotropic effect of insulin is pronounced in ICM, but underlying mechanisms are unaltered. The Ca2+‐independent PIE of insulin is mediated via glucose‐transporters. Together with the Ca2+‐dependent PI‐3‐kinase mediated pathway, it is responsible for the entire PIE. Substrate‐dependency affirms a glucose‐dependent part of the PIE.
The relationship between systolic blood pressure on admission and mortality in older patients with heart failure
Authors: Vidán María T. , Bueno Héctor , Wang Yongfei , Schreiner Geoffrey , Ross Joseph S. , Chen Jersey , Krumholz Harlan M. 
Published: January 2010

AimsTo determine the relationship between admission systolic blood pressure (SBP) and mortality in older patients hospitalized for heart failure (HF) and among various subgroups.Methods and resultsWe evaluated the independent association between initial SBP and 30‐day and 1‐year mortality, and potential interactions by age, gender, race, previous hypertension, and left ventricular dysfunction using multivariable logistic regression in the National Heart Failure Project, a database of Medicare patients >65 years old recruited from 1998 through 2001. Among 56 942 patients, mean admission SBP was 147.0 ± 92.3 mmHg, 15% presenting with SBP >180 mmHg. Systolic blood pressure showed an inverse relationship with 30‐day and 1‐year mortality rates in all subgroups analysed. Using admission SBP of 120–149 mmHg as the reference, the adjusted odds ratios (95% confidence intervals) for 1‐year mortality were 2.18 (1.77–2.69) for SBP <90 mmHg, 1.57 (1.47–1.69) for SBP 90–119 mmHg, 0.71 (0.67–0.76) for SBP 150–179 mmHg, 0.63 (0.57–0.68) for SBP 180–209 mmHg, and 0.51 (0.44–0.59) for SBP ≥210 mmHg.ConclusionHigher SBP on admission is associated with significant lower 30‐day and 1‐year mortality in patients hospitalized for HF. The relationship is strong, graded, independent of other clinical factors and consistent among subgroups.