518 research outputs found
The Pre-Main-Sequence Eclipsing Binary TY Coronae Australis: Precise Stellar Dimensions and Tests of Evolutionary Models
We analyze new photometric data for the Herbig Be eclipsing binary TY CrA, which securely reveal the secondary eclipse, ~0.03 mag deep in y. From the light-curve solution and our previous spectroscopic data, absolute dimensions of the primary and secondary stars are derived. The masses are found to be M1 = 3.16 ± 0.02 Mâ and M2 = 1.64 ± 0.01 Mâ, the radii are R1 = 1.80 ± 0.10 Râ and R2 = 2.08 ± 0.14 Râ, the luminosities are L1 = 67 ± 12 Lâ and L2 = 2.4 ± 0.8 Lâ, and the effective temperatures are T1 = 12,000 ± 500 K and T2 = 4900 ± 400 K. Here the uncertainties represent high-confidence limits, not standard deviations. The secondary star is a preâmain-sequence star located at the base of the Hayashi tracks. As such, it is the least evolved star with a dynamically measured mass. Given higher effective temperatures for the primary (e.g., 12,500 K), the solar-composition 1.64 Mâ evolutionary tracks of Swenson et al., Claret, and D'Antona & Mazzitelli are all consistent with the properties of the TY CrA secondary and suggest an age of order 3 Myr. The radius and projected rotational velocity of the secondary star are consistent with synchronous rotation. The primary star is located near the zero-age main sequence, which, for solar compositions, is consistent with an age of 3 Myr. However, the primary star is not well represented by any of the 3.16 Mâ evolutionary models, which predict somewhat higher effective temperatures than observed
Intrathoracic subclavian artery aneurysm repair in the thoracic endovascular aortic repair era
ObjectiveIntrathoracic subclavian artery aneurysms (SAAs) are rare aneurysms that often occur in association with congenital aortic arch anomalies and/or concomitant thoracic aortic pathology. The advent of thoracic endovascular aortic repair (TEVAR) methods may complement or replace conventional open SAA repair. Herein, we describe our experience with SAA repair in the TEVAR era.MethodsA retrospective review was performed of all intrathoracic SAAs repaired at a single institution since United States Food and Drug Administration approval of TEVAR in 2005.ResultsNineteen patients underwent 20 operations to repair 22 (13 native, nine aberrant) SAAs with an intrathoracic component. Mean SAA diameter was 3.1 cm (range, 1.6-6.0 cm). Mean patient age was 57 years (range, 24-80 years). Twenty-one percent (n = 4) of patients had a connective tissue disorder (two Loeys-Dietz, two Marfan). Thirty-six percent (n = 8) of SAAs were repaired by open techniques and 64% (n = 14) via a TEVAR-based approach. All TEVAR cases required proximal landing zone in the aortic arch (zone 0-2), and revascularization of at least one arch vessel was required in 83% (10/12) of patients. Concomitant repair of associated aortic pathology was performed in 50% (n = 10) of operations. Thirty-day/in-hospital rates of death, stroke, and permanent paraplegia/paraparesis were 5% (n = 1), 5% (n = 1), and 0%, respectively. Over mean (standard deviation) follow-up of 24 (21) months, 16% (n = 3) of patients required reintervention for subclavian artery bypass graft revision (n = 2) or type II endoleak (n = 1).ConclusionsThis is the largest single-institution series to date of TEVAR for SAA repair. Modern endovascular techniques expand SAA repair options with excellent results. The majority of SAAs and nearly all aberrant SAAs (Kommerell's diverticulum) can now be repaired using a TEVAR-based approach without the need for sternotomy or thoracotomy
Risk factors for 1-year mortality after thoracic endovascular aortic repair
ObjectiveThoracic endovascular aortic repair, although physiologically well tolerated, may fail to confer significant survival benefit in some high-risk patients. In an effort to identify patients most likely to benefit from intervention, the present study sought to determine the risk factors for 1-year mortality after thoracic endovascular aortic repair.MethodsA retrospective review was performed on prospectively collected data from all patients undergoing thoracic endovascular aortic repair from 2002 to 2010 at a single institution. Univariate analysis and multivariate Cox proportional hazards regression analysis were used to identify risk factors associated with mortality within 1 year after thoracic endovascular aortic repair.ResultsDuring the study period, 282 patients underwent at least 1 thoracic endovascular aortic repair; index procedures included descending aortic repair (n = 189), hybrid arch repair (n = 55), and hybrid thoracoabdominal repair (n = 38). The 30-day/in-hospital mortality was 7.4% (n = 21) and the overall 1-year mortality was 19% (n = 54). Cardiopulmonary pathologies were the most common cause of nonperioperative 1-year mortality (22%, n = 12). Multivariate modeling demonstrated 3 variables independently associated with 1-year mortality: age older than 75 years (hazard ratio, 2.26; P = .005), aortic diameter greater than 6.5 cm (hazard ratio, 2.20; P = .007), and American Society of Anesthesiologists class 4 (hazard ratio, 1.85; P = .049). A baseline creatinine greater than 1.5 mg/dL (hazard ratio, 1.79; P = .05) and congestive heart failure (hazard ratio, 1.87; P = .08) were also retained in the final model. These 5 variables explained a large proportion of the risk of 1-year mortality (C statistic = 0.74).ConclusionsAge older than 75 years, aortic diameter greater than 6.5 cm, and American Society of Anesthesiologists class 4 are independently associated with 1-year mortality after thoracic endovascular aortic repair. These clinical characteristics may help risk-stratify patients undergoing thoracic endovascular aortic repair and identify those unlikely to derive a long-term survival benefit from the procedure
Report on the âTrait-based approaches to ocean lifeâ scoping workshop, October 5-8, 2015
"Trait-based Approaches to Ocean Lifeâ Scoping Workshop, October 5-8, 2015, Waterville Valley, NH, USAFrom the introduction: Marine ecosystems are rich and biodiverse, often populated by thousands of competing and
interacting species with a vast range of behaviors, forms, and life histories. This great ecological
complexity presents a formidable challenge to understanding how marine ecosystems are
structured and controlled, but also how they respond to natural and anthropogenic changes. The
trait-based approach to ocean life is emerging as a novel framework for understanding the
complexity, structure, and dynamics of marine ecosystems, but also their broader significance.
Rather than considering species individually, organisms are characterized by essential traits that
capture key aspects of diversity. Trait distributions in the ocean emerge through evolution and
natural selection, and are mediated by the environment, biological interactions, anthropogenic
drivers, and organism behavior. Because trait variations within and across communities lead to
variation in the rates of crucial ecosystem functions such as carbon export, this mechanistic
approach sheds light on how variability in the environment, including climate change, impacts
marine ecosystems, biogeochemical cycles, and associated feedbacks to climate and society.Funding from
the National Science Foundation and National Aeronautics and Space Administration), the Simons
Foundation, and the Gordon and Betty Moore Foundation
Predicting live birth, preterm and low birth weight infant after in-vitro fertilisation: a prospective study of 144018 treatment cycles
Background
The extent to which baseline couple characteristics affect the probability of live birth and adverse perinatal outcomes after assisted conception is unknown.
Methods and Findings
We utilised the Human Fertilisation and Embryology Authority database to examine the predictors of live birth in all in vitro fertilisation (IVF) cycles undertaken in the UK between 2003 and 2007 (n = 144,018). We examined the potential clinical utility of a validated model that pre-dated the introduction of intracytoplasmic sperm injection (ICSI) as compared to a novel model. For those treatment cycles that resulted in a live singleton birth (n = 24,226), we determined the associates of potential risk factors with preterm birth, low birth weight, and macrosomia. The overall rate of at least one live birth was 23.4 per 100 cycles (95% confidence interval [CI] 23.2â23.7). In multivariable models the odds of at least one live birth decreased with increasing maternal age, increasing duration of infertility, a greater number of previously unsuccessful IVF treatments, use of own oocytes, necessity for a second or third treatment cycle, or if it was not unexplained infertility. The association of own versus donor oocyte with reduced odds of live birth strengthened with increasing age of the mother. A previous IVF live birth increased the odds of future success (OR 1.58, 95% CI 1.46â1.71) more than that of a previous spontaneous live birth (OR 1.19, 95% CI 0.99â1.24); p-value for difference in estimate <0.001. Use of ICSI increased the odds of live birth, and male causes of infertility were associated with reduced odds of live birth only in couples who had not received ICSI. Prediction of live birth was feasible with moderate discrimination and excellent calibration; calibration was markedly improved in the novel compared to the established model. Preterm birth and low birth weight were increased if oocyte donation was required and ICSI was not used. Risk of macrosomia increased with advancing maternal age and a history of previous live births. Infertility due to cervical problems was associated with increased odds of all three outcomesâpreterm birth, low birth weight, and macrosomia.
Conclusions
Pending external validation, our results show that couple- and treatment-specific factors can be used to provide infertile couples with an accurate assessment of whether they have low or high risk of a successful outcome following IVF
Physical modeling of unsteady turbulence in breaking tidal bores
A tidal bore is an unsteady flow motion generated by the rapid water level rise at the river mouth during the early flood tide under macrotidal and appropriate bathymetric conditions. This paper presents a study that physically investigates the turbulent properties of tidal bores. Results from some experimental measurements of free-surface fluctuations and turbulent velocities conducted on smooth and rough beds are reported. The free-surface measurements were conducted with Froude numbers of 1-1.7. Both undular and breaking bores were observed. Using an ensemble-averaging technique, the free-surface fluctuations of breaking tidal bores are characterized. Immediately before the roller, the free-surface curves gradually upwards. The passage of the bore roller is associated with some large water elevation fluctuations; the largest free-surface fluctuations are observed during the first half of the bore roller. The turbulent velocity measurements were performed at several vertical elevations during and shortly after the passage of breaking bores. Both the instantaneous and ensemble-averaged velocity data highlight a strong flow deceleration at all elevations during the bore passage. Close to the bed, the longitudinal velocity component becomes negative immediately after the roller passage, implying the existence of a transient recirculation. The height and duration of the transient are a function of the bed roughness, with a higher and longer recirculation region above the rough bed. The vertical velocity data presented some positive, upward motion beneath the front with increasing maximum vertical velocity with increasing distance from the bed. The transverse velocity data show some large fluctuations with nonzero ensemble average after the roller passage that highlight some intense secondary motion advected behind the bore front. DOI: 10.1061/(ASCE)HY.1943-7900.0000542. (C) 2012 American Society of Civil Engineers
Long-Term Follow-Up of the Intergroup Exemestane Study
Purpose: The Intergroup Exemestane Study, an investigator-led study of 4,724 postmenopausal patients with early breast cancer (clinical trial information: ISRCTN11883920), has previously demonstrated that a switch from adjuvant endocrine therapy after 2 to 3 years of tamoxifen to exemestane was associated with clinically relevant improvements in efficacy. Here, we report the final efficacy analyses of this cohort. Patients and Methods: Patients who remained disease free after 2 to 3 years of adjuvant tamoxifen were randomly assigned to continue tamoxifen or switch to exemestane to complete a total of 5 years of adjuvant endocrine therapy. Given the large number of nonâbreast cancerârelated deaths now reported, breast cancerâfree survival (BCFS), with censorship of intercurrent deaths, was the primary survival end point of interest. Analyses focus on patients with estrogen receptor-positive or unknown tumors (n = 4,599). Results: At the time of the data snapshot, median follow-up was 120 months. In the population that was estrogen receptor positive or had unknown estrogen receptor status, 1,111 BCFS events were observed with 508 (22.1%) of 2,294 patients in the exemestane group and 603 (26.2%) of 2,305 patients in the tamoxifen group. The data corresponded to an absolute difference (between exemestane and tamoxifen) at 10 years of 4.0% (95% CI, 1.2% to 6.7%), and the hazard ratio (HR) of 0.81 (95% CI, 0.72 to 0.92) favored exemestane. This difference remained in multivariable analysis that was adjusted for nodal status, prior use of hormone replacement therapy, and prior chemotherapy (HR, 0.80; 95% CI, 0.71 to 0.90; P < .001). A modest improvement in overall survival was seen with exemestane; the absolute difference (between exemestane and tamoxifen) at 10 years in the population that was estrogen receptor positive or had unknown estrogen receptor status was 2.1% (95% CI, â0.5% to 4.6%), and the HR was 0.89 (95% CI, 0.78 to 1.01; P = .08). For the intention-to-treat population, the absolute difference was 1.6% (95% CI, â0.9% to 4.1%); the HR was 0.91 (95% CI, 0.80 to 1.03, P = .15). No statistically significant difference was observed in the proportion of patients who reported a fracture event in the post-treatment period. Conclusion: The Intergroup Exemestane Study and contemporaneous studies have established that a strategy of switching to an aromatase inhibitor after 2 to 3 years of tamoxifen can lead to sustained benefits in terms of reduction of disease recurrence and breast cancer mortality
ElliPro: a new structure-based tool for the prediction of antibody epitopes
<p>Abstract</p> <p>Background</p> <p>Reliable prediction of antibody, or B-cell, epitopes remains challenging yet highly desirable for the design of vaccines and immunodiagnostics. A correlation between antigenicity, solvent accessibility, and flexibility in proteins was demonstrated. Subsequently, Thornton and colleagues proposed a method for identifying continuous epitopes in the protein regions protruding from the protein's globular surface. The aim of this work was to implement that method as a web-tool and evaluate its performance on discontinuous epitopes known from the structures of antibody-protein complexes.</p> <p>Results</p> <p>Here we present ElliPro, a web-tool that implements Thornton's method and, together with a residue clustering algorithm, the MODELLER program and the Jmol viewer, allows the prediction and visualization of antibody epitopes in a given protein sequence or structure. ElliPro has been tested on a benchmark dataset of discontinuous epitopes inferred from 3D structures of antibody-protein complexes. In comparison with six other structure-based methods that can be used for epitope prediction, ElliPro performed the best and gave an AUC value of 0.732, when the most significant prediction was considered for each protein. Since the rank of the best prediction was at most in the top three for more than 70% of proteins and never exceeded five, ElliPro is considered a useful research tool for identifying antibody epitopes in protein antigens. ElliPro is available at <url>http://tools.immuneepitope.org/tools/ElliPro</url>.</p> <p>Conclusion</p> <p>The results from ElliPro suggest that further research on antibody epitopes considering more features that discriminate epitopes from non-epitopes may further improve predictions. As ElliPro is based on the geometrical properties of protein structure and does not require training, it might be more generally applied for predicting different types of protein-protein interactions.</p
Near-Infrared and Optical Observations of Type Ic SN 2021krf: Luminous Late-time Emission and Dust Formation
We present near-infrared (NIR) and optical observations of the Type Ic
supernova (SN Ic) SN 2021krf obtained between days 13 and 259 at several
ground-based telescopes. The NIR spectrum at day 68 exhibits a rising -band
continuum flux density longward of 2.0 m, and a late-time optical
spectrum at day 259 shows strong [O I] 6300 and 6364 \r{A} emission-line
asymmetry, both indicating the presence of dust, likely formed in the SN
ejecta. We estimate a carbon-grain dust mass of 2 10
M and a dust temperature of 900 - 1200 K associated with this
rising continuum and suggest the dust has formed in SN ejecta. Utilizing the
one-dimensional multigroup radiation hydrodynamics code STELLA, we present two
degenerate progenitor solutions for SN 2021krf, characterized by C-O star
masses of 3.93 and 5.74 M, but with the same best-fit Ni mass
of 0.11 M for early times (0-70 days). At late times (70-300 days),
optical light curves of SN 2021krf decline substantially more slowly than that
expected from Co radioactive decay. Lack of H and He lines in the
late-time SN spectrum suggests the absence of significant interaction of the
ejecta with the circumstellar medium. We reproduce the entire bolometric light
curve with a combination of radioactive decay and an additional powering source
in the form of a central engine of a millisecond pulsar with a magnetic field
smaller than that of a typical magnetar.Comment: Accepted for publication in ApJ, 27 pages, 21 figures, 6 tables.
Previous arXiv submission (arXiv:2211.00205) replaced after acceptanc
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