The properties of early-type galaxies in the Ursa Major cluster

Using SDSS-DR7 and NASA/IPAC Extragalactic Database spectroscopic data, we identify 166 galaxies as members of the Ursa Major cluster with Mr < -13.5 mag. We morphological classify all galaxies by means of carefully inspecting g-, r-, i-band colour and monochromatic images. We show that the Ursa Major cluster is dominated by late-type galaxies, but also contains a significant number of early- type galaxies, particularly in the dwarf regime. We present further evidence for the existence of several subgroups in the cluster, consistent with previous findings. The early-type fraction is found to correlate with the mass of the subgroup. We also investigate environmental effects by comparing the properties of the Ursa Major early-type dwarf galaxies to those of the Virgo cluster. In contrast to the Virgo, the red sequence of the Ursa Major cluster is only sparsely populated in the optical and ultraviolet colour-magnitude relations. It also shows a statistically significant gap between -18 < Mr < -17 mag, i.e. the Ursa Major cluster lacks early-type dwarf galaxies at the bright end of their luminosity function. We discover that the majority of early-type dwarf galaxies in the Ursa Major cluster have blue cores with hints of recent or ongoing star formation. We suggest that gravitational tidal interactions can trigger central blue star forming regions in early-type dwarfs. After that, star formation would only fade completely when the galaxies experience ram pressure stripping or harassment, both of which are nearly absent in the Ursa Major cluster.Comment: 19 pages, 18 figures, 2 tables, Accepted for publication in MNRA

Who’s Following Twitter? Coverage of the Microblogging Phenomenon by U.S. Cable News Networks

Through data captured in a digital content analysis (DCA) lab, we examine coverage of Twitter across three 24-hour U.S. cable news channels: CNN, Fox News Channel, and MSNBC. This investigation tracked Twitter coverage from its initial stage, followed by its rise to a massively used tool and its subsequent diffusion into society, evident through its plateauing coverage. News stories covering Twitter, as it penetrated into society, were more likely to use benefit/gain frames when discussing the technology, highlighting its positive social, communicative, political, and participatory impact. Benefit frames were also likely to associate Twitter with journalism. Patterns emerging through the indicator graphs plotted by the DCA lab showed that the most intense coverage occurred during crisis situations, as Twitter coverage reached saturation, followed by increased personal daily usage of Twitter

The Extended Virgo Cluster Catalog

We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725 deg^2 or 60.1 Mpc^2. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000 kms^-1. In addition, 265 galaxies that have been missed in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies of which 676 galaxies are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.Comment: 69 pages, 29 figures, 4 tables, accepted for publication in the ApJ

What does a cell need for efficient protein secretion: Deciphering, modeling, and augmenting the CHO machinery

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Discovery of a large-scale H I plume in the NGC 7194 Group

We present the discovery of a new H I structure in the NGC 7194 group from the observations using the Karl G. Jansky Very Large Array. NGC 7194 group is a nearby (z ~ 0.027) small galaxy group with five quiescent members. The observations reveal a 200 kpc-long H I plume that spans the entire group with a total mass of M$_{HI}$ = 3.4 x 10$^{10}$ M$_{\odot}$. The line-of-sight velocity of the H I gas gradually increases from south (7200 km s$^{-1}$) to north (8200 km $^{-1}$), and the local velocity dispersion is up to 70 km s$^{-1}$. The structure is not spatially coincident with any member galaxies but it shows close associations with a number of blue star-forming knots. Intragroup H I gas is not rare, but this particular structure is still one of the unusual cases in the sense that it does not show any clear connection with sizable galaxies in the group. We discuss the potential origins of this large-scale H I gas in the NGC 7194 group and its relation with the intergalactic star-forming knots. We propose that this HI feature could have originated from tidal interactions among group members or the infall of a late-type galaxy into the group. Alternatively, it might be leftover gas from flyby intruders.Comment: 9 pages, 3 figure

Therapeutic end points for the treatment of atrioventricular node reentrant tachycardia by catheter-guided radiofrequency current

AbstractObjectives. The purpose off this prospective study was to test the hypothesis that the elimination of inducible repetitive atrioventricular (AV) node reentry the persistence of slow AV pathway conduction is a valid end point for radiofrequency catheter ablation procedures in patients with supraventricular tachycardia due to AV node reentry.Background. Although modification of AV node physiology by radiofrequency current can eliminate AV node reentrant tachycardia, therapeutic end points that are definitive of a satisfactory result in patients undergoing modification of the slow AV pathway have not been established. Applications of radiofrequency current at selected sites may eliminate all evidence of slow pathway conduction or sufficiently modify the refractory properties of the slow pathway to preclude sustained arrhythmias. Accordingly, total abolition of dual AV node physiology may not be necessary to prevent arrhythmia recurrence.Methods. Radiofrequency catheter ablation of the slow AV pathway was attempted in 59 patients with typical AV node reentry. Tissue ablation was performed with a continuous wave of 500-kHz radiofrequency current. Twenty-five to 35 W was applied for 60 s at the site selected for destruction.Results. Dual AV node physiology was eliminated completely in 35 patients (59%), persisted without inducible AV node reentry in 13 patients (22%) and persisted with inducible single AV reentrant beats in 11 patients (19%). In patients with persistent dual AV node physiology, the maximal difference between the effective refractory period of the fast and slow pathways was reduced from 104 ± 62 ms before the procedure to 37 ± 37 ms after AV conduction had been modified (p < 0.001). During a mean follow-up interval of 15 months (range 4 to 28), only one patient (2%) had a recurrence of the tachycardia.Conclusions. Resulte demonstrate that when complete elimination of dial AV node physiology is difficult, modification of slow pathway conduction to the extent that repetitive AV node reentry cannot be induced is a definitive end point that portends a good prognosis

REDUCE-IT USA: Results From the 3146 Patients Randomized in the United States.

BackgroundSome trials have found that patients from the United States derive less benefit than patients enrolled outside the United States. This prespecified REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl - Intervention Trial) subgroup analysis was conducted to determine the degree of benefit of icosapent ethyl in the United States.MethodsREDUCE-IT randomized 8179 statin-treated patients with qualifying triglycerides ≥135 and &lt;500 mg/dL and low-density lipoprotein cholesterol &gt;40 and ≤100 mg/dL and a history of atherosclerosis or diabetes mellitus to icosapent ethyl 4 g/d or placebo. The primary composite end point was cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or hospitalization for unstable angina. The key secondary composite end point was cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. A hierarchy was prespecified for examination of individual and composite end points.ResultsA total of 3146 US patients (38.5% of the trial) were randomized and followed for a median of 4.9 years; 32.3% were women and 9.7% were Hispanic. The primary composite end point occurred in 24.7% of placebo-treated patients versus 18.2% of icosapent ethyl-treated patients (hazard ratio [HR], 0.69 [95% CI, 0.59-0.80]; P=0.000001); the key secondary composite end point occurred in 16.6% versus 12.1% (HR, 0.69 [95% CI, 0.57-0.83]; P=0.00008). All prespecified hierarchical end points were meaningfully and significantly reduced, including cardiovascular death (6.7% to 4.7%; HR, 0.66 [95% CI, 0.49-0.90]; P=0.007), myocardial infarction (8.8% to 6.7%; HR, 0.72 [95% CI, 0.56-0.93]; P=0.01), stroke (4.1% to 2.6%; HR, 0.63 [95% CI, 0.43-0.93]; P=0.02), and all-cause mortality (9.8% to 7.2%; HR, 0.70 [95% CI, 0.55-0.90]; P=0.004); for all-cause mortality in the US versus non-US patients, Pinteraction=0.02. Safety and tolerability findings were consistent with the full study cohort.ConclusionsWhereas the non-US subgroup showed significant reductions in the primary and key secondary end points, the US subgroup demonstrated particularly robust risk reductions across a variety of individual and composite end points, including all-cause mortality.Clinical trial registrationURL: https://www.clinicaltrials.gov. Unique identifier: NCT01492361