453 research outputs found

    High-Resolution Infrared Spectroscopy of the Brown Dwarf Epsilon Indi Ba

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    We report on the analysis of high-resolution infrared spectra of the newly discovered brown dwarf Epsilon Indi Ba. This is the closest known brown dwarf to the solar system, with a distance of 3.626 pc. Spectra covering the ranges of 2.308-2.317 microns and 1.553-1.559 microns were observed at a spectral resolution of R=50,000 with the Phoenix spectrometer on the Gemini South telescope. The physical paramters of effective temperature and surface gravity are derived by comparison to model spectra calculated from atmospheres computed using unified cloudy models. An accurate projected rotational velocity is also derived.Comment: 9 pages, 3 figures. Astrophysical Journal Letters, in pres

    Roles of DnaK and RpoS in Starvation-Induced Thermotolerance of \u3ci\u3eEscherichia coli\u3c/i\u3e

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    DnaK is essential for starvation-induced resistance to heat, oxidation, and reductive division in Escherichia coli. Studies reported here indicate that DnaK is also required for starvation-induced osmotolerance, catalase activity, and the production of the RpoS-controlled Dps (PexB) protein. Because these dnaK mutant phenotypes closely resemble those of rpoS (o38) mutants, the relationship between DnaK and RpoS was evaluated directly during growth and starvation at 30°C in strains with genetically altered DnaK content. A starvation-specific effect of DnaK on RpoS abundance was observed. During carbon starvation, DnaK deficiency reduced RpoS levels threefold, while DnaK excess increased RpoS levels nearly twofold. Complementation of the dnaK mutation restored starvation-induced RpoS levels to normal. RpoS deficiency had no effect on the cellular concentration of DnaK, revealing an epistatic relationship between DnaK and RpoS. Protein half-life studies conducted at the onset of starvation indicate that DnaK deficiency significantly destabilized RpoS. RpoH (s32) suppressors of the dnaK mutant with restored levels of RpoS and dnaK rpoS double mutants were used to show that DnaK plays both an independent and an RpoS-dependent role in starvation-induced thermotolerance. The results suggest that DnaK coordinates sigma factor levels in glucose-starved E. coli

    Embedded-Cluster Calculations in a Numeric Atomic Orbital Density-Functional Theory Framework

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    We integrate the all-electron electronic structure code FHI-aims into the general ChemShell package for solid-state embedding (QM/MM) calculations. A major undertaking in this integration is the implementation of pseudopotential functionality into FHI-aims to describe cations at the QM/MM boundary through effective core potentials and therewith prevent spurious overpolarization of the electronic density. Based on numeric atomic orbital basis sets, FHI-aims offers particularly efficient access to exact exchange and second order perturbation theory, rendering the established QM/MM setup an ideal tool for hybrid and double-hybrid level DFT calculations of solid systems. We illustrate this capability by calculating the reduction potential of Fe in the Fe-substituted ZSM-5 zeolitic framework and the reaction energy profile for (photo-)catalytic water oxidation at TiO2(110).Comment: 12 pages, 4 figure

    Measuring deliberate reflection in residents: validation and psychometric properties of a measurement tool

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    PURPOSE: Reflective capacity is the ability to understand critical analysis of knowledge and experience to achieve deeper meaning. In medicine, there is little provision for post-graduate medical education to teach deliberate reflection. The feasibility, scoring characteristics, reliability, validation, and adaptability of a modified previously validated instrument was examined for its usefulness assessing reflective capacity in residents as a step toward developing interventions for improvement. METHODS: Third-year residents and fellows from four anesthesia training programs were administered a slightly modified version of the Reflection Evaluation for Learners\u27 Enhanced Competencies Tool (REFLECT) in a prospective, observational study at the end of the 2019 academic year. Six written vignettes of imperfect anesthesia situations were created. Subjects recorded their perspectives on two randomly assigned vignettes. Responses were scored using a 5-element rubric; average scores were analyzed for psychometric properties. An independent self-report assessment method, the Cognitive Behavior Survey: Residency Level (rCBS) was used to examine construct validity. Internal consistency (ICR, Cronbach\u27s alpha) and interrater reliability (weighted kappa) were examined. Pearson correlations were used between the two measures of reflective capacity. RESULTS: 46/136 invited subjects completed 2/6 randomly assigned vignettes. Interrater agreement was high (k = 0.85). The overall average REFLECT score was 1.8 (1-4 scale) with good distribution across the range of scores. ICR for both the REFLECT score (mean 1.8, sd 0.5; α = 0.92) and the reflection scale of the rCBS (mean 4.5, sd 1.1; α = 0.94) were excellent. There was a significant correlation between REFLECT score and the rCBS reflection scale (r = .44, p \u3c 0.01). CONCLUSIONS: This study demonstrates feasibility, reliability, and sufficiently robust psychometric properties of a modified REFLECT rubric to assess graduate medical trainees\u27 reflective capacity and established construct/convergent validity to an independent measure. The instrument has the potential to assess the effectiveness of interventions intended to improve reflective capacity

    Rare B decays and Tevatron top-pair asymmetry

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    The recent Tevatron result on the top quark forward-backward asymmetry, which deviates from its standard model prediction by 3.4σ\sigma, has prompted many authors to build new models to account for this anomaly. Among the various proposals, we find that those mechanisms which produce ttˉt\bar t via tt- or uu-channel can have a strong correlation to the rare B decays. We demonstrate this link by studying a model with a new charged gauge boson, WW'. In terms of the current measurements on BπKB\to \pi K decays, we conclude that the branching ratio for BπKˉ0B^-\to \pi^- \bar K^0 is affected most by the new effects. Furthermore, using the world average branching ratio for the exclusive B decays at 2σ2\sigma level, we discuss the allowed values for the new parameters. Finally, we point out that the influence of the new physics effects on the direct CP asymmetry in B decays is insignificant.Comment: 15 page, 6 figures, typos corrected and references added, final version to appear journa

    RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106

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    Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwesterm Oncology Group S1106 trial was designed to assess rituximab plushyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL
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