150 research outputs found

    Gas Mass Fractions and Star Formation in Blue-Sequence E/S0 Galaxies

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    Recent work has identified a population of low-redshift E/S0 galaxies that lie on the blue sequence in color vs. stellar mass parameter space, where spiral galaxies typically reside. While high-mass blue-sequence E/S0s often resemble young merger or interaction remnants likely to fade to the red sequence, we focus on blue-sequence E/S0s with lower stellar masses (< a few 10^10 M_sun), which are characterized by fairly regular morphologies and low-density field environments where fresh gas infall is possible. This population may provide an evolutionary link between early-type galaxies and spirals through disk regrowth. Focusing on atomic gas reservoirs, we present new GBT HI data for 27 E/S0s on both sequences as well as a complete tabulation of archival HI data for other galaxies in the Nearby Field Galaxy Survey. Normalized to stellar mass, the atomic gas masses for 12 of the 14 blue-sequence E/S0s range from 0.1 to >1.0. These gas-to-stellar mass ratios are comparable to those of spiral and irregular galaxies and have a similar dependence on stellar mass. Assuming that the HI is accessible for star formation, we find that many of our blue-sequence E/S0s can increase in stellar mass by 10-60% in 3 Gyr in both of two limiting scenarios, exponentially declining star formation and constant star formation. In a constant star formation scenario, about half of the blue-sequence E/S0s require fresh gas infall on a timescale of <3 Gyr to avoid exhausting their atomic gas reservoirs and evolving to the red sequence. We present evidence that star formation in these galaxies is bursty and likely involves externally triggered gas inflows. Our analysis suggests that most blue-sequence E/S0s are indeed capable of substantial stellar disk growth on relatively short timescales. (abridged)Comment: ApJ, accepted, 26 pages with 12 figures (5 color), 5 table

    E/S0 Galaxies on the Blue Color-Stellar Mass Sequence at z=0: Fading Mergers or Future Spirals?

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    We identify a population of morphologically defined E/S0 galaxies lying on the blue sequence at the present epoch. Using three samples, we analyze blue-sequence E/S0s with stellar masses >10^8 Msun, arguing that individual objects may be evolving either up toward the red sequence or down into the blue sequence. Blue-sequence E/S0 galaxies become more common with decreasing stellar mass, comprising <2% of E/S0s near the "shutdown mass" M_s ~ 1-2 x 10^11 Msun, increasing to >5% near the "bimodality mass" M_b ~ 3 x 10^10 Msun, and sharply rising to >20-30% below the "threshold mass" M_t ~ 4-6 x 10^9 Msun. The strong emergence of blue-sequence E/S0s below M_t coincides with a previously reported global increase in mean atomic gas fractions below M_t for galaxies of all types on both sequences, suggesting that the availability of cold gas may be basic to blue-sequence E/S0s' existence. Environmental analysis reveals that many sub-M_b blue-sequence E/S0s reside in low to intermediate density environments. In mass-radius and mass-sigma scaling relations, blue-sequence E/S0s are more similar to red-sequence E/S0s than to late-type galaxies, but they represent a transitional class. While some of them, especially in the high-mass range from M_b to M_s, resemble major-merger remnants that will likely fade onto the red sequence, most blue-sequence E/S0s below M_b show signs of disk and/or pseudobulge building, which may be enhanced by companion interactions. We argue that sub-M_b blue-sequence E/S0s occupy a "sweet spot" in stellar mass and concentration, with both abundant gas and optimally efficient star formation, which may enable the formation of large spiral disks. [abridged]Comment: AJ, submitted, revised, 21 pages with 15 figures (one in two parts, one color); full resolution version available at http://www.physics.unc.edu/~sheila/kgb.pd

    Reducing challenging behaviour of adults with intellectual disabilities in supported accommodation: A cluster randomized controlled trial of setting-wide positive behaviour support

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    Background: Improving the quality of social care through the implementation of setting-wide positive behaviour support (SWPBS) may reduce and prevent challenging behaviour. Method: Twenty-four supported accommodation settings were randomized to experimental or control conditions. Settings in both groups had access to individualized PBS either via the organisation’s Behaviour Support Team or from external professionals. Additionally, within the experimental group, social care practice was reviewed and improvement programmes set going. Progress was supported through coaching managers and staff to enhance their performance and draw more effectively on existing resources, and through monthly monitoring over 8–11 months. Quality of support, quality of life and challenging behaviour were measured at baseline and after intervention with challenging behaviour being additionally measured at long-term follow-up 12–18 months later. Results: Following intervention there were significant changes to social care practice and quality of support in the experimental group. Ratings of challenging behaviour declined significantly more in the experimental group and the difference between groups was maintained at follow-up. There was no significant difference between the groups in measurement of quality of life. Staff, family members and professionals evaluated the intervention and its outcomes positively. Conclusions: Some challenging behaviour in social care settings may be prevented by SWPBS that improves the quality of support provided to individuals

    Antibodies to SARS-CoV-2 are associated with protection against reinfection

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    Background: The relationship between the presence of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the risk of subsequent reinfection remains unclear. Methods: We investigated the incidence of SARS-CoV-2 infection confirmed by polymerase chain reaction (PCR) in seropositive and seronegative health care workers attending testing of asymptomatic and symptomatic staff at Oxford University Hospitals in the United Kingdom. Baseline antibody status was determined by anti-spike (primary analysis) and anti-nucleocapsid IgG assays, and staff members were followed for up to 31 weeks. We estimated the relative incidence of PCR-positive test results and new symptomatic infection according to antibody status, adjusting for age, participant-reported gender, and changes in incidence over time. Results: A total of 12,541 health care workers participated and had anti-spike IgG measured; 11,364 were followed up after negative antibody results and 1265 after positive results, including 88 in whom seroconversion occurred during follow-up. A total of 223 anti-spike–seronegative health care workers had a positive PCR test (1.09 per 10,000 days at risk), 100 during screening while they were asymptomatic and 123 while symptomatic, whereas 2 anti-spike–seropositive health care workers had a positive PCR test (0.13 per 10,000 days at risk), and both workers were asymptomatic when tested (adjusted incidence rate ratio, 0.11; 95% confidence interval, 0.03 to 0.44; P=0.002). There were no symptomatic infections in workers with anti-spike antibodies. Rate ratios were similar when the anti-nucleocapsid IgG assay was used alone or in combination with the anti-spike IgG assay to determine baseline status. Conclusions: The presence of anti-spike or anti-nucleocapsid IgG antibodies was associated with a substantially reduced risk of SARS-CoV-2 reinfection in the ensuing 6 months. (Funded by the U.K. Government Department of Health and Social Care and others.

    Antibody response to four doses of SARS-CoV-2 vaccine in rare autoimmune rheumatic diseases: an observational study

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    ObjectivesAntibody response to COVID-19 vaccines are reduced among immunocompromised patients but are not well-quantified among people with rare disease. We conducted an observational study to evaluate the antibody responses to the booster SARS-CoV-2 vaccine in people with rare autoimmune rheumatic diseases (RAIRD).MethodsBlood samples were collected after second, before third, after third and after fourth vaccine doses. Anti-spike and anti-nucleocapsid antibody levels were measured using an in-house ELISA assay. Logistic regression models were built to determine the predictors for non-response. Results were compared with age and sex matched healthy controls (HC).Results43 people with RAIRD were included, with a median age of 56 years. Anti-spike seropositivity increased from 42.9% after second dose to 51.2% after third dose and 65.6% after fourth dose. Median anti-spike antibody levels increased from 33.6 (IQR 7.8–724.5) post-second dose to 239.4 (IQR 35.8–1051.1) BAU after the booster dose (third dose, or fourth dose if eligible). 22.2% of participants who had sufficient antibody levels post-second dose had insufficient levels after the booster. 34.9% of participants had lower antibodies after the booster than the lowest HC had after the second dose. Rituximab in the six months prior to booster (p = 0.02) and non-white ethnicity (p = 0.04) was associated with non-response. There was a dose-response relationship between timing of rituximab and generation of sufficient antibodies (p = 0.03).ConclusionsAlthough the booster dose increased anti-spike IgG and seropositivity rates, some people with RAIRD, particularly those on rituximab, had insufficient antibody levels despite 3–4 doses

    Fatal COVID-19 outcomes are associated with an antibody response targeting epitopes shared with endemic coronaviruses

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    The role of immune responses to previously seen endemic coronavirus epitopes in severe acute respiratory coronavirus 2 (SARS-CoV-2) infection and disease progression has not yet been determined. Here, we show that a key characteristic of fatal coronavirus disease (COVID-19) outcomes is that the immune response to the SARS-CoV-2 spike protein is enriched for antibodies directed against epitopes shared with endemic beta-coronaviruses, and has a lower proportion of antibodies targeting the more protective variable regions of the spike. The magnitude of antibody responses to the SARS-CoV-2 full-length spike protein, its domains and subunits, and the SARS-CoV-2 nucleocapsid also correlated strongly with responses to the endemic beta-coronavirus spike proteins in individuals admitted to intensive care units (ICU) with fatal COVID-19 outcomes, but not in individuals with non-fatal outcomes. This correlation was found to be due to the antibody response directed at the S2 subunit of the SARS-CoV-2 spike protein, which has the highest degree of conservation between the beta-coronavirus spike proteins. Intriguingly, antibody responses to the less cross-reactive SARS-CoV-2 nucleocapsid were not significantly different in individuals who were admitted to ICU with fatal and non-fatal outcomes, suggesting an antibody profile in individuals with fatal outcomes consistent with an original antigenic sin type-response
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