We present a new catalogue of 55 121 groups and clusters centred on luminous red galaxies from Sloan Digital Sky Survey Data Release 7 in the redshift range 0.15 ≤z≤ 0.4. We provide halo mass (M
500) ...estimates for each of these groups derived from a calibration between the optical richness of bright galaxies (M
r
≤−20.5) within 1 Mpc and X-ray-derived mass for a small subset of 129 groups and clusters with X-ray measurements. For 20 157 high-mass groups and clusters with M
500 > 1013.7 M⊙, we find that the catalogue has a purity of >97 per cent and a completeness of ∼90 per cent. We derive the mean (stacked) surface number density profiles of galaxies as a function of total halo mass in different mass bins. We find that derived profiles can be well described by a projected Navarro-Frenk-White profile with a concentration parameter (〈c〉≡〈r
200/r
s〉≈ 2.6) that is approximately a factor of 2 lower than that of the dark matter (as predicted by N-body cosmological simulations) and nearly independent of halo mass. Interestingly, in spite of the difference in shape between the galaxy and dark matter radial distributions, both exhibit a high degree of self-similarity. We also stack the satellite profiles based on other observables, namely redshift, brightest cluster galaxy (BCG) luminosity and satellite luminosity and colour. We see no evidence for strong variation in profile shape with redshift over the range we probe or with BCG luminosity (or BCG luminosity fraction), but we do find a strong dependence on satellite luminosity and colours, in agreement with previous studies. A self-consistent comparison to several recent semi-analytic models of galaxy formation indicates that (1) beyond ≈0.3r
500 current models are able to reproduce both the shape and normalization of the satellite profiles, and (2) within ≈0.3r
500 the predicted profiles are sensitive to the details of the satellite-BCG merger time-scale calculation. The former is a direct result of the models being tuned to match the global galaxy luminosity function combined with the assumption that the satellite galaxies do not suffer significant tidal stripping, even though their surrounding dark matter haloes can be removed through this process. Combining our results with measurements of the intracluster light should provide a way to inform theoretical models on the efficacy of the tidal stripping and merging processes.
We employ a large sample of 20 171 optically selected groups and clusters at 0.15 ≤ z ≤ 0.4 in the Sloan Digital Sky Survey to investigate how the stacked stellar mass fraction varies across a wide ...range of total mass, M
500. Our study improves upon previous observational studies in a number of important ways, including having a much larger sample size, an explicit inclusion of the intracluster light (ICL) component and a thorough examination of the accuracy of our total mass estimates via comparisons to simulations and weak lensing observations. We find that the stellar mass fraction depends only weakly on total mass and that the contribution of ICL to the total stellar mass fraction is significant (typically 20-40 per cent). Both of these findings are in excellent accordance with the predictions of cosmological simulations. Under the assumption of a Chabrier (Salpeter) initial mass function, the derived star formation efficiency (f
star/f
b, where f
b ≡ Ωb/Ωm) is relatively low at 8 per cent (14 per cent) and is consistent with the global star formation efficiency of semi-analytic models that reproduce the galaxy stellar mass function. When our measured stellar mass fractions are combined with the observed relation between the hot gas mass fraction and total mass from X-ray observations, our results imply that galaxy groups have significantly lower baryon fractions than massive clusters. Ejection of gas due to energetic AGN feedback (most likely at high redshift) provides a plausible mechanism for explaining the trends we observe.
We investigate the relationship between the halo mass, M
200, and concentration, c, for a sample of 26 group- and cluster-scale strong gravitational lenses. In contrast with previous results, we find ...that these systems are only ∼0.1 dex more overconcentrated than similar-mass haloes from dark matter simulations; the concentration of a halo with M
200 = 1014 M is log c = 0.78 ± 0.05, while simulations of haloes with this mass at similar redshifts (z ∼ 0.4) predict log c ∼ 0.56-0.71. We also find that we are unable to make informative inference on the slope of the M
200-c relation in spite of our large sample size; we note that the steep slopes found in previous studies tend to follow the slope in the covariance between M
200 and c, indicating that these results may be measuring the scatter in the data rather than the intrinsic signal. Furthermore, we conclude that our inability to constrain the M
200-c slope is due to a limited range of halo masses, as determined by explicitly modelling our halo mass distribution, and we suggest that other studies may be producing biased results by using an incorrect distribution for their halo masses.
We present a new determination of the dust content and near-ultraviolet/optical extinction curves associated with a sample of ≃8300 strong, W
λ2796
0 > 1 Å, Mg ii absorbers, redshifts 0.4 < z < 2.2, ...identified in Sloan Digital Sky Survey (SDSS) spectra of quasars in the data release 6 (DR6). Taking into account the selection effects that result from dust extinction, including the reduction in the signal-to-noise ratio of an absorber appearing in a reddened quasar spectrum, we find a stronger dependence of E(B−V) on absorber W
λ2796
0 than in other published work. The dependence of the median reddening on W
λ2796
0 can be reproduced by the power-law model E(B−V) =(8.0 ± 3.0) × 10−4× (W
0)(3.48 ± 0.3) for 1.0 ≤W
0≤ 5.0. Observed Mg ii samples, derived from flux-limited quasar surveys, are shown to suffer from significant incompleteness at the level of 24 ± 4 per cent for absorbers with W
0 > 1 Å and 34 ± 2 per cent for absorbers with W
0 > 2 Å. Direct determination of the shape of the near-ultraviolet extinction curves, using high signal-to-noise ratio composites, for absorbers as a function of E(B−V), shows evidence for systematic changes in the form of the extinction curves. At low E(B−V) (≲0.05), the extinction curve is featureless and well represented by a Small Magellanic Cloud (SMC) like extinction curve. For intermediate E(B−V)s (≲0.2), approximately a third of Mg ii absorbers show evidence for a 2175 Å feature and an extinction curve similar to that of the Large Magellanic Cloud (LMC). For the small number of high E(B−V) (≳0.3) absorbers, the majority of which exhibit strong Ca iiλλ3935,3970 absorption, there is evidence for the presence of a 2175 Å feature as strong as that found in the Milky Way (MW). Near-infrared photometry for six of the systems indicates that the rest-frame optical portion of the extinction curve for these high E(B−V), and likely very high column density, systems is significantly greyer than the SMC, LMC or MW extinction curves. Application of the new results on the dust content of strong Mg ii absorbers shows that dusty absorbers can account for a significant proportion, up to a factor of 2, of the observed overdensity of absorbers seen towards gamma-ray burst (GRB) sightlines, compared to sightlines towards quasars in flux-limited samples.
We present a new determination of the dust content and near-ultraviolet/optical extinction curves associated with a sample of sime8300 strong, W lambda 27960 > 1Aa, Mgii absorbers, redshifts 0.4 < z ...< 2.2, identified in Sloan Digital Sky Survey (SDSS) spectra of quasars in the data release 6 (DR6). Taking into account the selection effects that result from dust extinction, including the reduction in the signal-to-noise ratio of an absorber appearing in a reddened quasar spectrum, we find a stronger dependence of E(B-V) on absorber W super( lambda 2796)0 than in other published work. The dependence of the median reddening on W super( lambda 2796) sub(0) can be reproduced by the power-law model E(B-V) =(8.0 +/- 3.0) 10 super(-4) (W sub(0)) super((3.48 +/- 0.3)) for 1.0 less than or equal to W sub(0) less than or equal to 5.0. Observed Mgii samples, derived from flux-limited quasar surveys, are shown to suffer from significant incompleteness at the level of 24 +/- 4 per cent for absorbers with W sub(0) > 1Aa and 34 +/- 2 per cent for absorbers with W sub(0) > 2Aa. Direct determination of the shape of the near-ultraviolet extinction curves, using high signal-to-noise ratio composites, for absorbers as a function of E(B-V), shows evidence for systematic changes in the form of the extinction curves. At low E(B-V) (lap0.05), the extinction curve is featureless and well represented by a Small Magellanic Cloud (SMC) like extinction curve. For intermediate E(B-V)s (lap0.2), approximately a third of Mgii absorbers show evidence for a 2175Aa feature and an extinction curve similar to that of the Large Magellanic Cloud (LMC). For the small number of high E(B-V) (gap0.3) absorbers, the majority of which exhibit strong Caii lambda lambda 3935,3970 absorption, there is evidence for the presence of a 2175Aa feature as strong as that found in the Milky Way (MW). Near-infrared photometry for six of the systems indicates that the rest-frame optical portion of the extinction curve for these high E(B-V), and likely very high column density, systems is significantly greyer than the SMC, LMC or MW extinction curves. Application of the new results on the dust content of strong Mg ii absorbers shows that dusty absorbers can account for a significant proportion, up to a factor of 2, of the observed overdensity of absorbers seen towards gamma-ray burst (GRB) sightlines, compared to sightlines towards quasars in flux-limited samples.
Although psychosocial therapy has been shown to reduce mortality after myocardial infarction, it is unknown whether the benefits of psychosocial therapy on mortality reduction extend to ...out-of-hospital sudden cardiac arrest, a main cause of cardiovascular mortality.
Describe efficacy of psychosocial therapy on two-year cardiovascular mortality in sudden cardiac arrest survivors.
Survivors of out-of-hospital ventricular fibrillation or asystole (N = 129), documented by electrocardiograms from registries of a citywide Medic One unit and two countywide emergency units, were randomized into a two group, experimental, longitudinal design. The intervention consisted of 11 individual sessions, implementing three components: physiologic relaxation with biofeedback training focused on altering autonomic tone; cognitive behavioral therapy aimed at self-management and coping strategies for depression, anxiety, and anger; and cardiovascular health education. The primary outcome measure was cardiovascular mortality.
Risk of cardiovascular death was significantly reduced 86% by psychosocial therapy, p = .03. Six of the seven cardiovascular deaths in the control group were caused by ventricular arrhythmias. The cardiovascular death in the therapy group was due to stroke. Controlling for depression, previous myocardial infarction, low ejection fraction, decreased heart rate variability, and ventricular ectopic beats had little impact on estimated treatment effect. The risk of all-cause mortality was reduced by 62% in the therapy group, p = .13. There were a total of three deaths in the therapy group and eight deaths in the control group.
Psychosocial therapy significantly reduced the risk of cardiovascular death in sudden cardiac arrest survivors.
Transcription by RNA Polymerase II (Pol II) is initiated by the hierarchical assembly of the pre-initiation complex onto promoter DNA. Decades of research have shown that the TATA-box binding protein ...(TBP) is essential for Pol II loading and initiation. Here, we report instead that acute depletion of TBP in mouse embryonic stem cells has no global effect on ongoing Pol II transcription. In contrast, acute TBP depletion severely impairs RNA Polymerase III initiation. Furthermore, Pol II transcriptional induction occurs normally upon TBP depletion. This TBP-independent transcription mechanism is not due to a functional redundancy with the TBP paralog TRF2, though TRF2 also binds to promoters of transcribed genes. Rather, we show that the TFIID complex can form and, despite having reduced TAF4 and TFIIA binding when TBP is depleted, the Pol II machinery is sufficiently robust in sustaining TBP-independent transcription.
Synthetic human MUC1 peptides are important candidates for therapeutic cancer vaccines. To explore whether a human MUC1 peptide BP25 (STAPPAHGVTSAPDTRPAPGSTAPP) can be rendered immunogenic by ...incorporation in liposomes, the effects of physical association of the peptide with liposomes on immune responses were investigated. Lipid conjugated and nonconjugated MUC1 peptides were incorporated in liposomes with a composition of distearoylphosphatidylcholine/cholesterol/dimyristoylphosphatidylglycerol (3:1:0.25, molar ratio) containing monophosphoryl lipid A (1% w/w of the total lipids). Liposomes were characterized for peptide retention by HPLC and for surface peptide display of MUC1 epitopes by flow cytometry. C57BL/6 mice were immunized with lipopeptide alone, peptide mixed with peptide-free liposomes, and peptide associated with liposomes in entrapped or surface-exposed forms. T cell proliferative responses, cytokine patterns, and antibody isotypes were studied. Results showed that immune responses were profoundly influenced by the liposome formulations. Physically associated, either encapsulated or surface-exposed, peptide liposomes elicited strong antigen-specific T cell responses, but not lipopeptide alone or peptide mixed with peptide-free liposomes. Analysis of the cytokines secreted by the proliferating T cells showed a high level of IFN-γ and undetectable levels of IL-4, indicating a T helper type 1 response. Thus, physical association of the peptide with liposomes was required for T cell proliferative responses, but the mode of association was not critical. On the other hand, the nature of the association significantly affected humoral immune responses. Only the surface-exposed peptide liposomes induced MUC1-specific antibodies. A domination of anti-MUC1 IgG2b over IgG1 (94 versus 6%) was observed. Our results support the hypothesis that different immune pathways are stimulated by different liposome formulations. This study demonstrated that a liposome delivery system could be tailored to induce either a preferential cellular or humoral immune response.
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