450 research outputs found

    Phonons in random alloys: the itinerant coherent-potential approximation

    Full text link
    We present the itinerant coherent-potential approximation(ICPA), an analytic, translationally invariant and tractable form of augmented-space-based, multiple-scattering theory in a single-site approximation for harmonic phonons in realistic random binary alloys with mass and force-constant disorder. We provide expressions for quantities needed for comparison with experimental structure factors such as partial and average spectral functions and derive the sum rules associated with them. Numerical results are presented for Ni_{55} Pd_{45} and Ni_{50} Pt_{50} alloys which serve as test cases, the former for weak force-constant disorder and the latter for strong. We present results on dispersion curves and disorder-induced widths. Direct comparisons with the single-site coherent potential approximation(CPA) and experiment are made which provide insight into the physics of force-constant changes in random alloys. The CPA accounts well for the weak force-constant disorder case but fails for strong force-constant disorder where the ICPA succeeds.Comment: 19 pages, 12 eps figures, uses RevTex

    Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

    Get PDF
    [This corrects the article DOI: 10.1186/s13054-016-1208-6.]

    TESS Discovery Of Twin Planets Near 2:1 Resonance Around Early M Dwarf TOI 4342

    Get PDF
    With data from the Transiting Exoplanet Survey Satellite (TESS), we showcase improvements to the MIT Quick Look Pipeline (QLP) through the discovery and validation of a multiplanet system around M dwarf TOI 4342 (Tmag = 11.032, M⋆ = 0.63 M⊙, R⋆ = 0.60 R⊙, Teff = 3900 K, d = 61.54 pc). With updates to QLP, including a new multiplanet search, as well as faster cadence data from TESS\u27s First Extended Mission, we discovered two sub-Neptunes (Rb = 2.266 (+0.038)/(-0.038) R⊕ and Rc = 2.415 (+0.043)/(-0.040) R⊕; Pb = 5.538 days and Pc = 10.689 days) and validated them with ground-based photometry, spectra, and speckle imaging. Both planets notably have high transmission spectroscopy metrics of 36 and 32, making TOI 4342 one of the best systems for comparative atmospheric studies. This system demonstrates how improvements to QLP, along with faster cadence full-frame images, can lead to the discovery of new multiplanet systems

    Programmatic Impact of QuantiFERON-TB Gold In-Tube Implementation on Latent Tuberculosis Diagnosis and Treatment in a Public Health Clinic

    Get PDF
    Background: QuantiFERON-TB Gold In-Tube (QFT-GIT) is considered an alternative to the tuberculin skin test (TST) for the diagnosis of tuberculosis (TB) infection, but the programmatic impact of QFT-GIT implementation is largely unknown. In March, 2010, the Baltimore City Health Department (BCHD) introduced routine QFT-GIT testing for individuals referred to the TB program for suspected latent TB infection (LTBI). Design: Retrospective study comparing LTBI diagnosis and treatment during the 13 months before and after QFT-GIT implementation at the BCHD TB clinic. Results: 607 and 750 individuals were referred by community-providers for suspected LTBI in the pre- and post-QFT-GIT periods, respectively. Most individuals in the pre- and post-QFT-GIT periods were referred on the basis of a positive TST (597/607 [98%] vs. 690/750 [92%], respectively) and were foreign-born (363/607[59%] vs. 507/750[68%], respectively). BCHD performed QFT-GIT testing for 375/543 (69%) eligible individuals in the post-QFT-GIT period, of which 185 (49%) were positive, 178 (47%) were negative, 1 (0.25%) was indeterminate, and 11 (3%) did not yield results. Concordance of QFT-GIT with TST was low (183/352[52%]). Foreign-born individuals had higher proportions of QFT-GIT positivity (57%) than US-born individuals (36%; AOR 3.3 [95%CI 1.7–6.2]). Significantly fewer individuals received a final diagnosis of LTBI in the post-QFT-GIT period (397/567 [70%]) compared to the pre-QFT-GIT period (445/452 [98%], p,0.001). In the post-QFT-GIT period, onl

    British HIV Association guidelines for the management of tuberculosis in adults living with HIV 2019

    Get PDF
    The overall purpose of these guidelines is to help physicians manage adults with tuberculosis (TB)/human immunodeficiency virus (HIV) co‐infection. Recommendations for the treatment of TB in HIV‐positive adults are similar to those in HIV‐negative adults. Of note, the term “HIV” refers to HIV‐1 throughout these guidelines

    Trials and Tribulations in the Reanalysis of KELT-24 b: a Case Study for the Importance of Stellar Modeling

    Full text link
    We present a new analysis of the KELT-24 system, comprising a well-aligned hot Jupiter, KELT-24~b, and a bright (V=8.3V=8.3), nearby (d=96.9 pcd=96.9~\mathrm{pc}) F-type host star. KELT-24~b was independently discovered by two groups in 2019, with each reporting best-fit stellar parameters that were notably inconsistent. Here, we present three independent analyses of the KELT-24 system, each incorporating a broad range of photometric and spectroscopic data, including eight sectors of TESS photometry and more than 200 new radial velocities (RVs) from MINERVA. Two of these analyses use KELT-24's observed spectral energy distribution (SED) through a direct comparison to stellar evolutionary models, while our third analysis assumes an unknown additional body contributing to the observed broadband photometry and excludes the SED. Ultimately, we find that the models that include the SED are a poor fit to the available data, so we adopt the system parameters derived without it. We also highlight a single transit-like event observed by TESS, deemed likely to be an eclipsing binary bound to KELT-24, that will require follow-up observations to confirm. We discuss the potential of these additional bodies in the KELT-24 system as a possible explanation for the discrepancies between the results of the different modeling approaches, and explore the system for longer-period planets that may be weakly evident in the RV observations. The comprehensive investigations that we present not only increase the fidelity of our understanding of the KELT-24 system, but also serve as a blueprint for future stellar modeling in global analyses of exoplanet systems.Comment: 27 pages, 18 figure

    Cytogenetics and gene mutations influence survival in older patients with acute myeloid leukemia treated with azacitidine or conventional care

    Get PDF
    Older patients with newly diagnosed acute myeloid leukemia (AML) in the phase 3 AZA-AML-001 study were evaluated at entry for cytogenetic abnormalities, and a subgroup of patients was assessed for gene mutations. Patients received azacitidine 75 mg/m2/day x7 days (n = 240) or conventional care regimens (CCR; n = 245): intensive chemotherapy, low-dose cytarabine, or best supportive care only. Overall survival (OS) was assessed for patients with common (occurring in ≥10% of patients) cytogenetic abnormalities and karyotypes, and for patients with recurring gene mutations. There was a significant OS improvement with azacitidine vs CCR for patients with European LeukemiaNet-defined Adverse karyotype (HR 0.71 [95%CI 0.51-0.99]; P = 0.046). Azacitidine-treated patients with -5/5q-, -7/7q-, or 17p abnormalities, or with monosomal or complex karyotypes, had a 31-46% reduced risk of death vs CCR. The most frequent gene mutations were DNMT3A (27%), TET2 (25%), IDH2 (23% [R140, 15%; R172, 8%]), and TP53 (21%). Compared with wild-type, OS was significantly reduced among CCR-treated patients with TP53 or NRAS mutations and azacitidine-treated patients with FLT3 or TET2 mutations. Azacitidine may be a preferred treatment for older patients with AML with Adverse-risk cytogenetics, particularly those with chromosome 5, 7, and/or 17 abnormalities and complex or monosomal karyotypes. The influence of gene mutations in azacitidine-treated patients warrants further study

    Transit Timings Variations In The Three-Planet System: TOI-270

    Get PDF
    We present ground- and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag = 8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1) and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using eight different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ~10 min and a super-period of ~3 yr, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modelling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of Mb = 1.48 ± 0.18 M⊕, Mc = 6.20 ± 0.31 M⊕, and Md = 4.20 ± 0.16 M⊕ for planets b, c, and d, respectively. We also detect small but significant eccentricities for all three planets : eb = 0.0167 ± 0.0084, ec = 0.0044 ± 0.0006, and ed = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H₂O atmosphere for the outer two. TOI-270 is now one of the best constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization

    Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)

    Full text link
    One of the main objectives of the Transiting Exoplanet Survey Satellite ({TESS}) mission is the discovery of small rocky planets around relatively bright nearby stars. Here, we report the discovery and characterization of the transiting super-Earth planet orbiting LHS~1478 (TOI-1640). The star is an inactive red dwarf (J9.6J \sim 9.6\,mag and spectral type m3\,V) with mass and radius estimates of 0.20±0.010.20\pm0.01\,MM_{\odot} and 0.25±0.010.25\pm0.01\,RR_{\odot}, respectively, and an effective temperature of 3381±543381\pm54\,K.It was observed by \tess in four sectors. These data revealed a transit-like feature with a period of 1.949 days. We combined the TESS data with three ground-based transit measurements, 57 radial velocity (RV) measurements from CARMENES, and 13 RV measurements from IRD, determining that the signal is produced by a planet with a mass of 2.330.20+0.202.33^{+0.20}_{-0.20}\,MM_{\oplus} and a radius of 1.240.05+0.051.24^{+0.05}_{-0.05}\,RR_{\oplus}. The resulting bulk density of this planet is 6.67\,g\,cm3^{-3}, which is consistent with a rocky planet with an Fe- and MgSiO3_3-dominated composition. Although the planet would be too hot to sustain liquid water on its surface (its equilibrium temperature is about \sim595\,K, suggesting a Venus-like atmosphere), spectroscopic metrics based on the capabilities of the forthcoming James Webb Space Telescope and the fact that the host star is rather inactive indicate that this is one of the most favorable known rocky exoplanets for atmospheric characterization.Comment: 14 pages, 10 figures, 6 tables, accepted for publication in A&
    corecore