1,884 research outputs found
Shuttle orbiter boundary layer transition at flight and wind tunnel conditions
Hypersonic boundary layer transition data obtained on the windward centerline of the Shuttle orbiter during entry for the first five flights are presented and analyzed. Because the orbiter surface is composed of a large number of thermal protection tiles, the transition data include the effects of distributed roughness arising from tile misalignment and gaps. These data are used as a benchmark for assessing and improving the accuracy of boundary layer transition predictions based on correlations of wind tunnel data taken on both aerodynamically rough and smooth orbiter surfaces. By comparing these two data bases, the relative importance of tunnel free stream noise and surface roughness on orbiter boundary layer transition correlation parameters can be assessed. This assessment indicates that accurate predications of transition times can be made for the orbiter at hypersonic flight conditions by using roughness dominated wind tunnel data. Specifically, times of transition onset and completion is accurately predicted using a correlation based on critical and effective values of a roughness Reynolds number previously derived from wind tunnel data
Sensitive Chemical Compass Assisted by Quantum Criticality
The radical-pair-based chemical reaction could be used by birds for the
navigation via the geomagnetic direction. An inherent physical mechanism is
that the quantum coherent transition from a singlet state to triplet states of
the radical pair could response to the weak magnetic field and be sensitive to
the direction of such a field and then results in different photopigments in
the avian eyes to be sensed. Here, we propose a quantum bionic setup for the
ultra-sensitive probe of a weak magnetic field based on the quantum phase
transition of the environments of the two electrons in the radical pair. We
prove that the yield of the chemical products via the recombination from the
singlet state is determined by the Loschmidt echo of the environments with
interacting nuclear spins. Thus quantum criticality of environments could
enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure
Aerodynamic Parameter Estimation for the X-43A (Hyper-X) from Flight Data
Aerodynamic parameters were estimated based on flight data from the third flight of the X-43A hypersonic research vehicle, also called Hyper-X. Maneuvers were flown using multiple orthogonal phase-optimized sweep inputs applied as simultaneous control surface perturbations at Mach 8, 7, 6, 5, 4, and 3 during the vehicle descent. Aerodynamic parameters, consisting of non-dimensional longitudinal and lateral stability and control derivatives, were estimated from flight data at each Mach number. Multi-step inputs at nearly the same flight conditions were also flown to assess the prediction capability of the identified models. Prediction errors were found to be comparable in magnitude to the modeling errors, which indicates accurate modeling. Aerodynamic parameter estimates were plotted as a function of Mach number, and compared with estimates from the pre-flight aerodynamic database, which was based on wind-tunnel tests and computational fluid dynamics. Agreement between flight estimates and values computed from the aerodynamic database was excellent overall
Rationale and evidence for the incorporation of heparin to the diclofenac epolamine medicated plaster
The nonsteroidal anti-inflammatory drug (NSAID) diclofenac epolamine (DHEP) formulated as a topical patch has demonstrated efficacy and safety in the localized treatment of acute pain from minor strains, sprains, and contusions, and for epicondylitis and knee osteoarthritis. The glycosaminoglycan heparin enhances the activity of topical NSAIDs formulated as a medicated plaster, even in the absence of any significant release of heparin. Therefore, DHEP Plus, a new formulation of the DHEP medicated plaster containing a small amount of heparin sodium as excipient has been developed.
Methods: We reviewed the pivotal and supportive studies of the clinical development program of the new patch and evaluated the role of heparin as an enhancer in the treatment of localized pain/inflammation of musculoskeletal structures, associated with post-traumatic and/or rheumatic conditions.
Results: The data were consistent with the concept that heparin increased the clinical activity of the DHEP Plus medicated plaster versus the reference DHEP medicated plaster through improved bioavailability due to enhanced movement of diclofenac from the plaster. Both DHEP formulations have the same dissolution profile, indicating that heparin does not change the physical and chemical characteristics of the plaster. Permeation testing showed that heparin is not released from the DHEP Plus medicated plaster. Efficacy studies showed that the DHEP Plus medicated plaster was significantly more effective in reducing pain than the reference marketed DHEP medicated plaster.
Conclusions: The benefit/risk assessment of DHEP Plus 180 mg medicated plaster is favorable, with a safety profile equal to placebo and improved efficacy over the reference marketed DHEP medicated plaster
Space Shuttle orbiter entry heating and TPS response: STS-1 predictions and flight data
Aerothermodynamic development flight test data from the first orbital flight test of the Space Transportation System (STS) transmitted after entry blackout is given. Engineering predictions of boundary layer transition and numerical simulations of the orbiter flow field were confirmed. The data tended to substantiate preflight predictions of surface catalysis phenomena. The thermal response of the thermal protection system was as expected. The only exception is that internal free convection was found to be significant in limiting the peak temperature of the structure in areas which do not have internal insulation
Mapping the genetic architecture of gene expression in human liver
Genetic variants that are associated with common human diseases do not lead directly to disease, but instead act on intermediate, molecular phenotypes that in turn induce changes in higher-order disease traits. Therefore, identifying the molecular phenotypes that vary in response to changes in DNA and that also associate with changes in disease traits has the potential to provide the functional information required to not only identify and validate the susceptibility genes that are directly affected by changes in DNA, but also to understand the molecular networks in which such genes operate and how changes in these networks lead to changes in disease traits. Toward that end, we profiled more than 39,000 transcripts and we genotyped 782,476 unique single nucleotide polymorphisms (SNPs) in more than 400 human liver samples to characterize the genetic architecture of gene expression in the human liver, a metabolically active tissue that is important in a number of common human diseases, including obesity, diabetes, and atherosclerosis. This genome-wide association study of gene expression resulted in the detection of more than 6,000 associations between SNP genotypes and liver gene expression traits, where many of the corresponding genes identified have already been implicated in a number of human diseases. The utility of these data for elucidating the causes of common human diseases is demonstrated by integrating them with genotypic and expression data from other human and mouse populations. This provides much-needed functional support for the candidate susceptibility genes being identified at a growing number of genetic loci that have been identified as key drivers of disease from genome-wide association studies of disease. By using an integrative genomics approach, we highlight how the gene RPS26 and not ERBB3 is supported by our data as the most likely susceptibility gene for a novel type 1 diabetes locus recently identified in a large-scale, genome-wide association study. We also identify SORT1 and CELSR2 as candidate susceptibility genes for a locus recently associated with coronary artery disease and plasma low-density lipoprotein cholesterol levels in the process. © 2008 Schadt et al
Inflatable Re-entry Vehicle Experiment (IRVE-4) Overview
The suite of Inflatable Re-Entry Vehicle Experiments (IRVE) is designed to further our knowledge and understanding of Hypersonic Inflatable Aerodynamic Decelerators (HIADs). Before infusion into a future mission, three challenges need to be addressed: surviving the heat pulse during re-entry, demonstrating system performance at relevant scales, and demonstrating controllability in the atmosphere. IRVE-4 will contribute to a better understanding of controllability by characterizing how a HIAD responds to a set of controlled inputs. The ability to control a HIAD is vital for missions that are g-limited, require precision targeting and guidance for aerocapture or entry, descent, and landing. The IRVE-4 flight test will focus on taking a first look into controlling a HIAD. This paper will give an overview of the IRVE-4 mission including the control response portion of the flight test sequence, and will provide a review of the mission s development
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