3,766 research outputs found
Deployable platform systems development
The long range objective is to achieve technology readiness for one or more deployable platform systems by 1986. Engineering plans and approaches to meet this goal are presented in outline form
Quantification of Cross-coupling and Motion Feedthrough for Multiaxis Controllers Used in an Air Combat Flying Task
A real-time piloted simulation of an air-to-air combat flying task using a wings-level-turn aircraft and various novel controllers was conducted. One objective is to quantify how the pilot interacts with the controllers and control modes, including: (1) controller versus aircraft response; (2) proprioceptive cross-coupling among axes of the controllers; and (3) biodynamic cross-coupling between the aircraft motions and the controllers. In order to aid in identifying the items listed above, both the target aircraft and the large amplitude multimode aerospace research simulator (LAMARS) motion system were distributed with quasi-random sums-of-sinusoids. Since the disturbances were separated in frequency, spectral analysis techniques were used to identify the three items listed. The results of the spectral analysis of controller motions from the two-axis side stick, a twist grip mounted on the side stick, a thumb button mounted on the side stick, and conventional rudder pedals are presented. Conclusions and recommendations for further research are also presented
Cellular distribution of the prion protein in palatine tonsils of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni)
Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) that affects members of the Cervidae family, including deer (Odocoileus spp.), elk (Cervus Canadensis spp.), and moose (Alces alces spp.). While CWD is a neurodegenerative disease, lymphoid accumulation of the abnormal isoform of the prion protein (PrPSc) is detectable early in the course of infection. It has been shown that a large portion of the PrPSc lymphoid accumulation in infected mule deer takes place on the surface of follicular dendritic cells (FDCs). In mice, FDC expression of PrPC has been shown to be essential for PrPSc accumulation. FDCs have been shown to normally express high levels of PrPC in mice and humans but this has not been examined in natural hosts for CWD. We used double immunofluorescent labeling and confocal microscopy to determine the PrPC expression characteristics of B and T lymphocytes as well as FDCs in palatine tonsils of CWD-negative mule deer and elk. We detected substantial PrPC colocalization with all cellular phenotypic markers used in this study, not just with FDC phenotypic markers
A preliminary look at control augmented dynamic response of structures
The augmentation of structural characteristics, mass, damping, and stiffness through the use of control theory in lieu of structural redesign or augmentation was reported. The standard single-degree-of-freedom system was followed by a treatment of the same system using control augmentation. The system was extended to elastic structures using single and multisensor approaches and concludes with a brief discussion of potential application to large orbiting space structures
Gas Bubbles Emerging from a Submerged Granular Bed
This fluid dynamics video was submitted to the Gallery of Fluid Motion for
the 2009 APS Division of Fluid Dynamics Meeting in Minneapolis, Minnesota. In
this video we show some results from a simple experiment where air was injected
by a single nozzle at known constant flow rates in the bottom of a granular bed
submerged in water. The injected air propagates through the granular bed in one
of two modes. Mode 1 emergence involves small discrete bubbles taking tortuous
paths through the interstitial space of the bed. Multiple small bubbles can be
emitted from the bed in an array of locations at the same time during Mode 1
emergence. Mode 2 emergence involves large discrete bubbles locally fluidizing
the granular bed and exiting the bed approximately above the injection site.
Bead diameter, bead density, and air flow rate were varied to investigate the
change in bubble release behavior at the top of the granular bed.
This system is a useful model for methane seeps in lakes. Methane bubbles are
released from the decomposition of organic matter in the lake bed. The initial
size of the bubble determines how much of the gas is absorbed into the lake and
how much of the gas reaches the surface and is released into the atmosphere.
The size and behavior of the emerging bubbles may also affect the amount of
vertical mixing occurring in the lake, as well as the mixing from the lake bed
into the benthic layer.Comment: 2009 APS DFD Gallery of Fluid Motion Submissio
Space Shuttle Main Engine (SSME) Pogo testing and results
To effectively assess the Pogo stability of the space shuttle vehicle, it was necessary to characterize the structural, propellant, and propulsion dynamics subsystems. Extensive analyses and comprehensive testing programs were established early in the project as an implementation of management philosophy of Pogo prevention for space shuttle. The role of the space shuttle main engine (SSMF) in the Pogo prevention plans, the results obtained from engine ground testing with analysis, and measured data from STS-1 flight are discussed
Bar-holding prosthetic limb
A prosthetic device for below-the-elbow amputees is disclosed. The device has a removable effector, which is attached to the end of an arm cuff. The effector is comprised of a pair of C-shaped members that are oriented so as to face each other. Working in concert, the C-shaped members are able to hold a bar such as a chainsaw handle. A flat spring is fitted around the C-shaped members to hold them together
Effectiveness of group-based self-management education for individuals with Type 2 diabetes:A systematic review with meta-analyses and meta-regression
Aims:
Patient education for the management of Type 2 diabetes can be delivered in various forms, with the goal of promoting and supporting positive self-management behaviours. This systematic review aimed to determine the effectiveness of group-based interventions compared with individual interventions or usual care for improving clinical, lifestyle and psychosocial outcomes in people with Type 2 diabetes.
Methods:
Six electronic databases were searched. Group-based education programmes for adults with Type 2 diabetes that measured glycated haemoglobin (HbA1c) and followed participants for ≥ 6 months were included. The primary outcome was HbA1c, and secondary outcomes included fasting blood glucose, weight, body mass index, waist circumference, blood pressure, blood lipid profiles, diabetes knowledge and self-efficacy.
Results:
Fifty-three publications describing 47 studies were included (n = 8533 participants). Greater reductions in HbA1c occurred in group-based education compared with controls at 6–10 months [n = 30 studies; mean difference (MD) = 3 mmol/mol (0.3%); 95% confidence interval (CI): −0.48, −0.15; P = 0.0002], 12–14 months [n = 27 studies; MD = 4 mmol/mol (0.3%); 95% CI: −0.49, −0.17; P < 0.0001], 18 months [n = 3 studies; MD = 8 mmol/mol (0.7%); 95% CI: −1.26, −0.18; P = 0.009] and 36–48 months [n = 5 studies; MD = 10 mmol/mol (0.9%); 95% CI: −1.52, −0.34; P = 0.002], but not at 24 months. Outcomes also favoured group-based education for fasting blood glucose, body weight, waist circumference, triglyceride levels and diabetes knowledge, but not at all time points. Interventions facilitated by a single discipline, multidisciplinary teams or health professionals with peer supporters resulted in improved outcomes in HbA1c when compared with peer-led interventions.
Conclusions:
Group-based education interventions are more effective than usual care, waiting list control and individual education at improving clinical, lifestyle and psychosocial outcomes in people with Type 2 diabetes.No Full Tex
“I’m Running So You Can Be Happy and I Can Keep My Scholarship”: A Comparative Study of Black Male College Athletes’ Experiences With Role Conflict
The purpose of this study was to examine the experiences of two groups of Black male college athletes at a Division I historically White institution (HWI) to better understand the key contributors that influenced their academic performance levels, academic engagement, and the quality of their overall college experiences. Two focus groups were conducted with 10 Black male college athletes enrolled at a Division I HWI and a demographic questionnaire was administered to ascertain a better understanding of their personal backgrounds, college academic experiences, and college athletic experiences. Role theory was incorporated as a theoretical lens to investigate the participants’ identity salience, role commitments, and overall college experiences. Findings revealed participants from each group shared common experiences encountering role conflict. However, the coping strategies and academic performance outcomes varied between each group. Implications for policy and practice are discussed
CMB likelihood approximation by a Gaussianized Blackwell-Rao estimator
We introduce a new CMB temperature likelihood approximation called the
Gaussianized Blackwell-Rao (GBR) estimator. This estimator is derived by
transforming the observed marginal power spectrum distributions obtained by the
CMB Gibbs sampler into standard univariate Gaussians, and then approximate
their joint transformed distribution by a multivariate Gaussian. The method is
exact for full-sky coverage and uniform noise, and an excellent approximation
for sky cuts and scanning patterns relevant for modern satellite experiments
such as WMAP and Planck. A single evaluation of this estimator between l=2 and
200 takes ~0.2 CPU milliseconds, while for comparison, a single pixel space
likelihood evaluation between l=2 and 30 for a map with ~2500 pixels requires
~20 seconds. We apply this tool to the 5-year WMAP temperature data, and
re-estimate the angular temperature power spectrum, , and likelihood,
L(C_l), for l<=200, and derive new cosmological parameters for the standard
six-parameter LambdaCDM model. Our spectrum is in excellent agreement with the
official WMAP spectrum, but we find slight differences in the derived
cosmological parameters. Most importantly, the spectral index of scalar
perturbations is n_s=0.973 +/- 0.014, 1.9 sigma away from unity and 0.6 sigma
higher than the official WMAP result, n_s = 0.965 +/- 0.014. This suggests that
an exact likelihood treatment is required to higher l's than previously
believed, reinforcing and extending our conclusions from the 3-year WMAP
analysis. In that case, we found that the sub-optimal likelihood approximation
adopted between l=12 and 30 by the WMAP team biased n_s low by 0.4 sigma, while
here we find that the same approximation between l=30 and 200 introduces a bias
of 0.6 sigma in n_s.Comment: 10 pages, 7 figures, submitted to Ap
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