Airloads on bluff bodies, with application to the rotor-induced downloads on tilt-rotor aircraft

The aerodynamic characteristics of airfoils with several flap configurations were studied theoretically and experimentally in environments that simulate a wing immersed in the downwash of a hovering rotor. Special techniques were developed for correcting and validating the wind tunnel data for large blockage effects, and the test results were used to evaluate two modern blockage effects, and the test results were used to evaluate two modern computational aerodynamics codes. The combined computed and measured results show that improved flap and leading-edge configurations can be designed which will achieve large reductions in the downloads of tilt-rotor aircraft, and thereby improve their hover efficiency

Thermomechanical response of NiTi shape-memory nanoprecipitates in TiV alloys

We study the properties of NiTi shape-memory nanoparticles coherently embedded in TiV matrices using three-dimensional atomistic simulations based on the modified embedded-atom method. To this end, we develop and present a suitable NiTiV potential for our simulations. Employing this potential, we identify the conditions under which the martensitic phase transformation of such a nanoparticle is triggered—specifically, how these conditions can be tuned by modifying the size of the particle, the composition of the surrounding matrix, or the temperature and strain state of the system. Using these insights, we establish how the transformation temperature of such particles can be influenced and discuss the practical implications in the context of shape-memory strengthened alloys

Nickel-rhenium compound sheds light on the potency of rhenium as a strengthener in high-temperature nickel alloys

For many decades, it has been known that rhenium imparts a tremendous resistance to creep to the nickel-based high-temperature alloys colloquially known as superalloys. This effect is so pronounced that is has been dubbed "the rhenium effect." Its origins are ill-understood, even though it is so critical to the performance of these high-temperature alloys. In this paper we show that the currently known phase diagram is inaccurate, and neglects a stoichiometric compound at 20 at.% Re (Ni4Re). The presence of this precipitate at low temperatures and the short-range ordering of Re in fcc-Ni observed at higher temperatures have important ramifications for the Ni-based superalloys. The Ni4Re compound is shown to be stable by quantum mechanical high-throughput calculations at 0 K. Monte Carlo simulations show that it is thermally persistent up to ≈930 K when considering configurational entropy. The existence of this compound is investigated using extended x-ray absorption fine spectroscopy on a Ni96.62Re3.38 alloy

Modeling the Cognitive Mechanisms Linking Autism Symptoms and Anxiety in Adults

Emotional acceptance, alexithymia, and intolerance of uncertainty (IU) contribute to anxiety disorders in neurotypical populations. Their association with anxiety in people diagnosed with autism spectrum disorder (ASD) has not been studied. We aimed to model the contributions of these constructs on the relationship between dimensional measures of autism and anxiety. Participants were 151 adults recruited from 2 sites, including those diagnosed with ASD (n = 76) and a matched comparison group (n = 75). All participants completed a battery of questionnaires measuring core autism symptoms, anxiety, emotional acceptance, alexithymia, and intolerance of uncertainty. Structural equation modeling with mediation was used to examine directional relationships among these variables. Autism symptoms directly predicted less emotional acceptance and increased alexithymia and IU. Alexithymia and acceptance were shown to explain 64% of the effect between autism symptom severity and anxiety level. This suggests that people with ASD experience increased levels of anxiety because they are more likely to react aversively to their emotional experiences, while lacking the ability to identify and understand their emotions. Developing and implementing mindfulness-based interventions aimed at assuaging alexithymia and IU, while increasing emotional acceptance, may be especially helpful in treating anxiety in ASD

Clinical characteristics of emergency department heart failure patients initially diagnosed as non-heart failure

BACKGROUND: Since previous studies suggest the emergency department (ED) misdiagnosis rate of heart failure is 10–20% we sought to describe the characteristics of ED patients misdiagnosed as non-decompensated heart failure in the ED. METHODS: We analyzed a prospective convenience sample of 439 patients at 4 emergency departments who presented with signs or symptoms of decompensated heart failure. Patients with a cardiology criterion standard diagnosis of decompensated heart failure and an ED diagnosis of decompensated heart failure were compared to patients with a criterion standard of decompensated heart failure but no ED diagnosis of decompensated heart failure. Two senior cardiology fellows retrospectively determined the patient's heart failure status during their acute ED presentation. The Mann-Whitney u-test for two groups, the Kruskall-Wallis test for multiple groups, or Chi-square tests, were used as appropriate. RESULTS: There were 173 (39.4%) patients with a criterion standard diagnosis of decompensated heart failure. Among those with this criterion standard diagnosis of decompensated heart failure, discordant patients without an ED diagnosis of decompensated heart failure (n = 58) were more likely to have a history of COPD (p = 0.017), less likely to have a previous history of heart failure (p = 0.014), and less likely to have an elevated b-type natriuretic peptide (BNP) level (median 518 vs 764 pg/ml; p = 0.038) than those who were given a concordant ED diagnosis of decompensated heart failure. BNP levels were higher in those with a criterion standard diagnosis of decompensated heart failure than in those without a criterion standard diagnosis (median 657 vs 62.7 pg/ml). However, 34.6% of patients with decompensated heart failure had BNP levels in the normal (<100 pg/ml; 6.1%) or indeterminate range (100–500 pg/ml; 28.5%). CONCLUSION: We found the ED diagnoses of decompensated heart failure to be discordant with the criterion standard in 14.3% of patients, the vast majority of which were due to a failure to diagnose heart failure when it was present. Patients with a previous history of COPD, without a previous history of heart failure and with lower BNP levels were more likely to have an ED misdiagnosis of non-decompensated heart failure. Readily available, accurate, objective ED tests are needed to improve the early diagnosis of decompensated heart failure in ED patients

Extended Time, Elevated Expectations: the Unappreciated Downsides of Pausing the Tenure Clock

In 1971, Stanford became the first university to introduce tenure clock extensions in academia for new mothers. The American Association of University Professors (AAUP) began recommending such policies a few years later, and in 2001, modified their recommendation to include primary or coequal caregivers, following either the birth or adoption of a child (1). By 2004, 43% of 255 surveyed institutions had formal clock-stop policies..

B-type natriuretic peptide levels predict extent and severity of coronary disease in non-ST elevation coronary syndromes and normal left ventricular systolic function.

BACKGROUND: B-type natriuretic peptide (BNP) has been used recently as a biological marker in patients with coronary artery disease (CAD) with ST-elevation, as well as without ST-elevation. BNP is able to predict systolic dysfunction, adding new prognostic information to existing traditional markers. However is not known if there is a relation between the quantity of BNP levels and the severity of coronary artery disease. METHODS: This study compared B-type natriuretic peptide (BNP) levels in patients with stable angina (SA) and acute coronary syndromes (ACS) without ST-elevation in relation to angiographic lesions using TIMI and Gensini Scores. We studied 282 patients with CAD without ST elevation and preserved systolic function. BNP samples were measured in all recruited patients within 24 hours of hospitalization. RESULTS: BNP values were progressively increased in relation to the severity of diagnosis: SA (52.6±49.4 pg/mL ) UA (243.3±212 pg/mL) NSTE-ACS (421.7±334 pg/mL) (p<0.0001 and p<0.007 respectively). No statistically significant difference was observed between patients with SA and controls (21.2±6.8 pg/mL). The analysis of BNP levels in relation to the number of involved vessels demonstrated significantly increased levels in patients with multivessel disease compared to patients with 1 or 2 vessel disease (1-86.2±46.3 pg/mL; 2-127±297 pg/mL; 3-295±318 pg/mL; 4-297±347 pg/mL p<0.001 and p<0.003). Evaluation of BNP using Gensini Score showed a strong relation between BNP and coronary disease extension (r=0.38 p<0.0001).This trend was maintained in all CAD groups (SA=r 0.54; UA r=0.36 NSTE-ACS r=0.28). CONCLUSIONS: Circulating BNP levels appear elevated in ACS with diffuse coronary involvement, even in the absence of systolic dysfunction. BNP is also associated with multi-vessel disease and the extension of coronary disease

Thermomechanical response of NiTi shape-memory nanoprecipitates in TiV alloys

We study the properties of NiTi shape-memory nanoparticles coherently embedded in TiV matrices using three-dimensional atomistic simulations based on the modified embedded-atom method. To this end, we develop and present a suitable NiTiV potential for our simulations. Employing this potential, we identify the conditions under which the martensitic phase transformation of such a nanoparticle is triggered - specifically, how these conditions can be tuned by modifying the size of the particle, the composition of the surrounding matrix, or the temperature and strain state of the system. Using these insights, we establish how the transformation temperature of such particles can be influenced and discuss the practical implications in the context of shape-memory strengthened alloys