Preliminary rotor wake measurements with a laser velocimeter

A laser velocimeter (LV) was used to determine rotor wake characteristics. The effect of various fuselage widths and rotor-fuselage spacings on time averaged and detailed time dependent rotor wake velocity characteristics was defined. Definition of time dependent velocity characteristics was attempted with the LV by associating a rotor azimuth position with each velocity measurement. Results were discouraging in that no apparent time dependent velocity characteristics could be discerned from the LV measurements. Since the LV is a relatively new instrument in the rotor wake measurement field, the cause of this lack of periodicity is as important as the basic research objectives. An attempt was made to identify the problem by simulated acquisition of LV-type data for a predicted rotor wake velocity time history. Power spectral density and autocorrelation function estimation techniques were used to substantiate the conclusion that the primary cause of the lack of time dependent velocity characteristics was the nonstationary flow condition generated by the periodic turbulence level that currently exists in the open throat configuration of the wind tunnel

Pyrotechnic shock at the orbiter/external tank forward attachment

During the initial certification test of the forward structural attachment of the space shuttle orbiter to the external tank, pyrotechnic shock from actuation of the separation device resulted in structural failure of the thermal protection tiles surrounding the attachment. Because of the high shock associated with the separation bolt, the development of alternative low shock separation designs was initiated. Two concepts that incorporate a 5.08 centimeter frangible nut as the release device were developed and tested

Observation of a possible superflare on Proxima Centauri

We report the observation on UT 2017 July 1 of an unusually powerful flare detected in near-infrared continuum photometry of Proxima Centauri. During a campaign monitoring the star for possible exoplanet transits, we identified an increase in Sloan i' flux leading to an observed peak at BJD 2457935.996 that was at least 10 per cent over pre-flare flux in this band. It was followed by a two-component rapid decline in the first 100 s that became a slower exponential decay with time constant of 1350 s. A smaller flare event 1300 s after the first added an incremental peak flux increase of 1 per cent of pre-flare flux. Since the onset of the flare was not fully time resolved at a cadence of 62 s, its actual peak value is unknown but greater than the time average over a single exposure of 20 s. The i' band is representative of broad optical and near-IR continuum flux over which the integrated energy of the flare is 100 times the stellar luminosity. This meets the criteria that established the concept of superflares on similar stars. The resulting implied ultraviolet flux and space weather could have had an extreme effect on the atmospheres of planets within the star's otherwise habitable zone

A smart end-effector for assembly of space truss structures

A unique facility, the Automated Structures Research Laboratory, is being used to investigate robotic assembly of truss structures. A special-purpose end-effector is used to assemble structural elements into an eight meter diameter structure. To expand the capabilities of the facility to include construction of structures with curved surfaces from straight structural elements of different lengths, a new end-effector has been designed and fabricated. This end-effector contains an integrated microprocessor to monitor actuator operations through sensor feedback. This paper provides an overview of the automated assembly tasks required by this end-effector and a description of the new end-effector's hardware and control software

A review of the clinical utility of the Enhanced Liver Fibrosis test in multiple aetiologies of chronic liver disease

The rising incidence of chronic liver disease continues to be an increasing health burden. The morbidity and mortality associated with chronic liver disease typically occur in patients with advanced fibrosis. Hence, early identification of those at-risk is of vital importance to ensure appropriate ongoing management. Currently, tools for appropriate risk stratification remain limited. Increasing awareness of the limitations of liver biopsy has driven research into alternative non-invasive methods of fibrosis assessment including serological markers assessing functional changes. One such biomarker, the Enhanced Liver Fibrosis test, was initially validated in a cohort of 1021 patients with mixed aetiology chronic liver disease and shown to perform well. Since this pathfinder study, it has been independently validated in cohorts of hepatitis C, non-alcoholic fatty liver disease, alcoholic liver disease, primary biliary cirrhosis and primary sclerosing cholangitis. In addition to performing well as a diagnostic tool, the Enhanced Liver Fibrosis test has been shown to outperform liver biopsy in prognostic studies and is the only non-invasive marker to do so. However, questions remain regarding the use of this test, particularly regarding the possible effect age and alcohol may have on test scores. This review examines the current literature published in relation to the Enhanced Liver Fibrosis test and its clinical utility and highlights areas requiring further study

Factors Influencing Depression and Anxiety among Black Sexual Minority Men

The primary aim of this study was to examine the relationships between depression and anxiety, and ethnic and sexual identity development, and discrimination and harassment (DH) among Black sexual minority men. Additional aims were to determine whether an interaction effect existed between ethnic and sexual identity and whether coping skills level moderated these relationships. Using an observational cross-sectional design, 54 participants recruited through snowball sampling completed self-administered online surveys. Stepwise multiple regression analysis was used. Sixty-four percent of the variance in depression scores and 53% of the variance in anxiety scores were explained by DH and internalized homonegativity together. Thirty percent of the sample had scale scores indicating likelihood of depression and anxiety. Experience of DH and internalized homonegativity explained a large portion of the variability in depression and anxiety among Black sexual minority men. The study showed high prevalence of mental distress among this sample

Lognormal scale invariant random measures

In this article, we consider the continuous analog of the celebrated Mandelbrot star equation with lognormal weights. Mandelbrot introduced this equation to characterize the law of multiplicative cascades. We show existence and uniqueness of measures satisfying the aforementioned continuous equation; these measures fall under the scope of the Gaussian multiplicative chaos theory developed by J.P. Kahane in 1985 (or possibly extensions of this theory). As a by product, we also obtain an explicit characterization of the covariance structure of these measures. We also prove that qualitative properties such as long-range independence or isotropy can be read off the equation.Comment: 31 pages; Probability Theory and Related Fields (2012) electronic versio

A flux-matched gyrokinetic analysis of DIII-D L-mode turbulence

Previous nonlinear gyrokinetic simulations of specific DIII-D L-mode cases have been found to significantly underpredict the ion heat transport and associated density and temperature fluctuation levels by up to almost one of order of magnitude in the outer-core domain, i.e., roughly in the last third of the minor radius. Since then, this so-called shortfall issue has been subject to various speculations on possible reasons and furthermore motivation for a number of dedicated comparisons for L-mode plasmas in comparable machines. However, only a rather limited number of simulations and gyrokinetic codes has been applied to the original scenario, thus calling for further dedicated investigations in order to broaden the scientific basis. The present work contributes along these lines by employing another well-established gyrokinetic code in a numerically and physically comprehensive manner. Contrary to the previous studies, only a mild underprediction is observed at the outer radial positions which can furthermore be overcome by varying the ion temperature gradient within the error bars associated with the experimental measurement. The significance and reliability of these simulations are demonstrated by benchmarks, numerical convergence tests, and furthermore by extensive validation studies. The latter involve cross-phase and cross-power spectra analyses of various fluctuating quantities and confirm a high degree of realism. The code discrepancies come as a surprise since the involved software packages had been benchmarked repeatedly and very successfully in the past. Further collaborative effort in identifying the underlying difference is hence required.European Union. Horizon 2020 Research and Innovation Programme (Grant 633053

Galectin-3 interacts with the cell surface glycoprotein CD146 (MCAM, MUC18) and induces secretion of metastasis-promoting cytokines from vascular endothelial cells

The galactoside-binding protein galectin-3 is increasingly recognized as an important player in cancer development, progression, and metastasis via its interactions with various galactoside-terminated glycans. We have shown previously that circulating galectin-3, which is increased up to 30-fold in cancer patients, promotes blood-borne metastasis in an animal cancer model. This effect is partly attributable to the interaction of galectin-3 with unknown receptor(s) on vascular endothelial cells and causes endothelial secretion of several metastasis-promoting cytokines. Here we sought to identify the galectin-3-binding molecule(s) on the endothelial cell surface responsible for the galectin-3-mediated cytokine secretion. Using two different galectin-3 affinity purification processes, we extracted four cell membrane glycoproteins, CD146/melanoma cell adhesion molecule (MCAM)/MUC18, CD31/platelet endothelial cell adhesion molecule-1 (PECAM-1), CD144/VE-cadherin, and CD106/Endoglin, from vascular endothelial cells. CD146 was the major galectin-3-binding ligand and strongly co-localized with galectin-3 on endothelial cell surfaces treated with exogenous galectin-3. Moreover, galectin-3 bound to N-linked glycans on CD146 and induced CD146 dimerization and subsequent activation of AKT signaling. siRNA-mediated suppression of CD146 expression completely abolished the galectin-3-induced secretion of IL-6 and G-CSF cytokines from the endothelial cells. Thus, CD146/MCAM is the functional galectin-3-binding ligand on endothelial cell surfaces responsible for galectin-3-induced secretion of metastasis-promoting cytokines. We conclude that CD146/MCAM interactions with circulating galectin-3 may have an important influence on cancer progression and metastasis