24 research outputs found

    Mind the Gap: A Case Study in Instructor Intention and Feedback

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    While effective instructor written feedback is critical, the process is often the least understood and is a detriment to student success when improperly applied. This case study identifies strategies that characterize successful instructor written feedback for students\u27 written assignments in an introductory college composition course. My research examines instructor feedback within the diverse environment of the community college thus highlighting the importance of instructor knowledge of composition pedagogy and feedback methods and approaches. A review of literature on instructor feedback identifies instructor and student collaboration as a key component for success together with understanding of historical trends in the field of composition studies. This case study includes five individual interviews with introductory composition community college instructors and a textual analysis of twenty samples of formative and summative instructor feedback to student submissions . Bloom \u27s Taxonomy is used to graph alignment of stated instructor goals in relation to resulting written feedback. Study findings reveal a discrepancy or gap between instructor approaches to and goals for feedback and the resulting written feedback. An evaluation of the gap between the instructor approach and the resulting written feedback helped develop implications for teaching in any introductory composition course. The implications of the study reveal that understanding various approaches when setting goals and providing written feedback together with knowledge of the history of composition pedagogy are powerful tools in the introductory composition course

    The surprisingly low carbon mass in the debris disk around HD 32297

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    Gas has been detected in a number of debris disks. It is likely secondary, i.e. produced by colliding solids. Here, we report ALMA Band 8 observations of neutral carbon in the CO-rich debris disk around the 15--30 Myr old A-type star HD 32297. We find that C0^0 is located in a ring at ∌\sim110 au with a FWHM of ∌\sim80 au, and has a mass of (3.5±0.2)×10−3(3.5\pm0.2)\times10^{-3} M⊕_\oplus. Naively, such a surprisingly small mass can be accumulated from CO photo-dissociation in a time as short as ∌\sim104^4 yr. We develop a simple model for gas production and destruction in this system, properly accounting for CO self-shielding and shielding by neutral carbon, and introducing a removal mechanism for carbon gas. We find that the most likely scenario to explain both C0^0 and CO observations, is one where the carbon gas is rapidly removed on a timescale of order a thousand years and the system maintains a very high CO production rate of ∌\sim15 M⊕_\oplus Myr−1^{-1}, much higher than the rate of dust grind-down. We propose a possible scenario to meet these peculiar conditions: the capture of carbon onto dust grains, followed by rapid CO re-formation and re-release. In steady state, CO would continuously be recycled, producing a CO-rich gas ring that shows no appreciable spreading over time. This picture might be extended to explain other gas-rich debris disks.Comment: accepted for publication in the Ap

    Empirical Constraints on Turbulence in Protoplanetary Accretion Disks

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    We present arcsecond-scale Submillimeter Array observations of the CO(3-2) line emission from the disks around the young stars HD 163296 and TW Hya at a spectral resolution of 44 m/s. These observations probe below the ~100 m/s turbulent linewidth inferred from lower-resolution observations, and allow us to place constraints on the turbulent linewidth in the disk atmospheres. We reproduce the observed CO(3-2) emission using two physical models of disk structure: (1) a power-law temperature distribution with a tapered density distribution following a simple functional form for an evolving accretion disk, and (2) the radiative transfer models developed by D'Alessio et al. that can reproduce the dust emission probed by the spectral energy distribution. Both types of models yield a low upper limit on the turbulent linewidth (Doppler b-parameter) in the TW Hya system (<40 m/s), and a tentative (3-sigma) detection of a ~300 m/s turbulent linewidth in the upper layers of the HD 163296 disk. These correspond to roughly <10% and 40% of the sound speed at size scales commensurate with the resolution of the data. The derived linewidths imply a turbulent viscosity coefficient, alpha, of order 0.01 and provide observational support for theoretical predictions of subsonic turbulence in protoplanetary accretion disks.Comment: 18 pages, 9 figures, accepted for publication in Ap

    Systematic review: Effects, design choices, and context of pay-for-performance in health care

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    <p>Abstract</p> <p>Background</p> <p>Pay-for-performance (P4P) is one of the primary tools used to support healthcare delivery reform. Substantial heterogeneity exists in the development and implementation of P4P in health care and its effects. This paper summarizes evidence, obtained from studies published between January 1990 and July 2009, concerning P4P effects, as well as evidence on the impact of design choices and contextual mediators on these effects. Effect domains include clinical effectiveness, access and equity, coordination and continuity, patient-centeredness, and cost-effectiveness.</p> <p>Methods</p> <p>The systematic review made use of electronic database searching, reference screening, forward citation tracking and expert consultation. The following databases were searched: Cochrane Library, EconLit, Embase, Medline, PsychINFO, and Web of Science. Studies that evaluate P4P effects in primary care or acute hospital care medicine were included. Papers concerning other target groups or settings, having no empirical evaluation design or not complying with the P4P definition were excluded. According to study design nine validated quality appraisal tools and reporting statements were applied. Data were extracted and summarized into evidence tables independently by two reviewers.</p> <p>Results</p> <p>One hundred twenty-eight evaluation studies provide a large body of evidence -to be interpreted with caution- concerning the effects of P4P on clinical effectiveness and equity of care. However, less evidence on the impact on coordination, continuity, patient-centeredness and cost-effectiveness was found. P4P effects can be judged to be encouraging or disappointing, depending on the primary mission of the P4P program: supporting minimal quality standards and/or boosting quality improvement. Moreover, the effects of P4P interventions varied according to design choices and characteristics of the context in which it was introduced.</p> <p>Future P4P programs should (1) select and define P4P targets on the basis of baseline room for improvement, (2) make use of process and (intermediary) outcome indicators as target measures, (3) involve stakeholders and communicate information about the programs thoroughly and directly, (4) implement a uniform P4P design across payers, (5) focus on both quality improvement and achievement, and (6) distribute incentives to the individual and/or team level.</p> <p>Conclusions</p> <p>P4P programs result in the full spectrum of possible effects for specific targets, from absent or negligible to strongly beneficial. Based on the evidence the review has provided further indications on how effect findings are likely to relate to P4P design choices and context. The provided best practice hypotheses should be tested in future research.</p

    Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

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    IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

    Clinical Outcomes Following Implantation of Thin-Strut, Bioabsorbable Polymer-Coated, Everolimus-Eluting SYNERGY Stents Final 5-Year Results of the EVOLVE II Randomized Trial

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    BACKGROUND: The thin-strut SYNERGY stent has an abluminal everolimus-eluting bioabsorbable polymer coating designed to facilitate vascular healing and reduce risk of stent thrombosis. In the multicenter, randomized EVOLVE II trial (The EVOLVE II Clinical Trial to Assess the SYNERGY Stent System for the Treatment of Atherosclerotic Lesion[s]), SYNERGY was noninferior to the durable polymer PROMUS Element Plus everolimus-eluting stent for the primary end point of 1-year target lesion failure. Longer-term clinical follow-up will support the relative efficacy and safety of SYNERGY. METHODS: Patients with ≀3 native coronary lesions (reference vessel diameter ≄2.25-≀4.00 mm; length ≀34 mm) in ≀2 major epicardial vessels were randomized 1:1 to SYNERGY (N=838) or PROMUS Element Plus (N=846). EVOLVE II included a Diabetes substudy which pooled patients with diabetes mellitus from the randomized controlled trial (n=263) and from a sequential, single-arm substudy (N=203). RESULTS: The 5-year target lesion failure rate was 14.3% for SYNERGY and 14.2% for PROMUS Element Plus (P=0.91). Landmark analysis demonstrated similar rates of target lesion failure from discharge to 1-year (P=0.90) and from 1 to 5 years (P=0.94). Definite/probable stent thrombosis was infrequent in both arms (SYNERGY 0.7% versus PROMUS Element Plus 0.9%; P=0.75). There were no significant differences in the rates of cardiac death, myocardial infarction, or revascularization. Among patients with diabetes mellitus, the target lesion failure rate to 1-year was noninferior to a prespecified performance goal and to 5 years was 17.0%. CONCLUSIONS: SYNERGY demonstrated comparable outcomes to PROMUS Element Plus, with low rates of stent thrombosis and adverse events through 5 years of follow-up. Five-year clinical outcomes were favorable in patients with diabetes mellitus. These data support the long-term safety and effectiveness of SYNERGY in a broad range of patients. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01665053.status: publishe

    Clinical Outcomes Following Implantation of Thin-Strut, Bioabsorbable Polymer-Coated, Everolimus-Eluting SYNERGY Stents.

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    BACKGROUND The thin-strut SYNERGY stent has an abluminal everolimus-eluting bioabsorbable polymer coating designed to facilitate vascular healing and reduce risk of stent thrombosis. In the multicenter, randomized EVOLVE II trial (The EVOLVE II Clinical Trial to Assess the SYNERGY Stent System for the Treatment of Atherosclerotic Lesion[s]), SYNERGY was noninferior to the durable polymer PROMUS Element Plus everolimus-eluting stent for the primary end point of 1-year target lesion failure. Longer-term clinical follow-up will support the relative efficacy and safety of SYNERGY. METHODS Patients with ≀3 native coronary lesions (reference vessel diameter ≄2.25-≀4.00 mm; length ≀34 mm) in ≀2 major epicardial vessels were randomized 1:1 to SYNERGY (N=838) or PROMUS Element Plus (N=846). EVOLVE II included a Diabetes substudy which pooled patients with diabetes mellitus from the randomized controlled trial (n=263) and from a sequential, single-arm substudy (N=203). RESULTS The 5-year target lesion failure rate was 14.3% for SYNERGY and 14.2% for PROMUS Element Plus (P=0.91). Landmark analysis demonstrated similar rates of target lesion failure from discharge to 1-year (P=0.90) and from 1 to 5 years (P=0.94). Definite/probable stent thrombosis was infrequent in both arms (SYNERGY 0.7% versus PROMUS Element Plus 0.9%; P=0.75). There were no significant differences in the rates of cardiac death, myocardial infarction, or revascularization. Among patients with diabetes mellitus, the target lesion failure rate to 1-year was noninferior to a prespecified performance goal and to 5 years was 17.0%. CONCLUSIONS SYNERGY demonstrated comparable outcomes to PROMUS Element Plus, with low rates of stent thrombosis and adverse events through 5 years of follow-up. Five-year clinical outcomes were favorable in patients with diabetes mellitus. These data support the long-term safety and effectiveness of SYNERGY in a broad range of patients. CLINICAL TRIAL REGISTRATION URL: https://www.clinicaltrials.gov. Unique identifier: NCT01665053

    Efficacy and safety of a novel bioabsorbable polymer-coated, everolimus-eluting coronary stent: the EVOLVE II Randomized Trial.

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    BACKGROUND Drug eluting stents with durable polymers may be associated with hypersensitivity, delayed healing, and incomplete endothelialization, which may contribute to late/very late stent thrombosis and the need for prolonged dual antiplatelet therapy. Bioabsorbable polymers may facilitate stent healing, thus enhancing clinical safety. The SYNERGY stent is a thin-strut, platinum chromium metal alloy platform with an ultrathin bioabsorbable Poly(D,L-lactide-co-glycolide) abluminal everolimus-eluting polymer. We performed a multicenter, randomized controlled trial for regulatory approval to determine noninferiority of the SYNERGY stent to the durable polymer PROMUS Element Plus everolimus-eluting stent. METHODS AND RESULTS Patients (n=1684) scheduled to undergo percutaneous coronary intervention for non-ST-segment-elevation acute coronary syndrome or stable coronary artery disease were randomized to receive either the SYNERGY stent or the PROMUS Element Plus stent. The primary end point of 12-month target lesion failure was observed in 6.7% of SYNERGY and 6.5% PROMUS Element Plus treated subjects by intention-to-treat (P=0.83 for difference; P=0.0005 for noninferiority), and 6.4% in both the groups by per-protocol analysis (P=0.0003 for noninferiority). Clinically indicated revascularization of the target lesion or definite/probable stent thrombosis were observed in 2.6% versus 1.7% (P=0.21) and 0.4% versus 0.6% (P=0.50) of SYNERGY versus PROMUS Element Plus-treated subjects, respectively. CONCLUSIONS In this randomized trial, the SYNERGY bioabsorbable polymer everolimus-eluting stent was noninferior to the PROMUS Element Plus everolimus-eluting stent with respect to 1-year target lesion failure. These data support the relative safety and efficacy of SYNERGY in a broad range of patients undergoing percutaneous coronary intervention. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01665053
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