2,926 research outputs found
Liquid drop stability for protein crystal growth in microgravity
It is possible to grow protein crystals for biomedical research in microgravity by deploying a protein-rich solution from a syringe, forming a drop in which crystallization can occur with the proper degree of supersaturation. Drop stability is critical to the success of this research, due to the large drop sizes which can be achieved in space. In order to determine the type of syringe tips most suitable to support these large drops, tests were performed during brief periods of weightlessness onboard the NASA KC-135 low-gravity simulation aircraft. The drops were analyzed using three simple models in which the samples were approximated by modified pendulum and spring systems. It was concluded that the higher frequency systems were the most stable, indicating that of the syringes utilized, a disk-shaped configuration provided the most stable environment of low-gravity protein crystal growth
Analysis techniques for residual acceleration data
Various aspects of residual acceleration data are of interest to low-gravity experimenters. Maximum and mean values and various other statistics can be obtained from data as collected in the time domain. Additional information may be obtained through manipulation of the data. Fourier analysis is discussed as a means of obtaining information about dominant frequency components of a given data window. Transformation of data into different coordinate axes is useful in the analysis of experiments with different orientations and can be achieved by the use of a transformation matrix. Application of such analysis techniques to residual acceleration data provides additional information than what is provided in a time history and increases the effectiveness of post-flight analysis of low-gravity experiments
Probability of Detection Study for Visual Inspection of Steel Bridges: Volume 2—Full Project Report
An inspector’s ability to correctly identify surface and internal defects in steel bridge components is critical to protecting public safety. Ensuring that inspectors are properly trained and adequately equipped to detect these defects in locations that are difficult to access and/or in unfavorable environmental conditions must be a high priority. While the Federal Highway Administration and individual state departments of transportation have guidelines for inspector qualifications, trainings, and certifications, there is very little emphasis placed on evaluating or “testing: a given inspector’s capability to characterize defects in the field. As a result, there is also very little, if any, data on how well a given inspector actually performs or the variability which can be expected between inspectors.
This comprehensive Probability of Detection (POD) study was conducted to establish the ability of an inspector with the current required training to locate and quantify cracks in steel bridge components. This study is believed to be the first statistically-significant study of its kind in the United States
Probability of Detection Study for Visual Inspection of Steel Bridges: Volume 1—Executive Summary
An inspector’s ability to correctly identify surface and internal defects in steel bridge components is critical to protecting public safety. Ensuring that inspectors are properly trained and adequately equipped to detect these defects in locations that are difficult to access and/or in unfavorable environmental conditions must be a high priority. While the Federal Highway Administration and individual state departments of transportation have guidelines for inspector qualifications, trainings, and certifications, there is very little emphasis placed on evaluating or “testing” a given inspector’s capability to characterize detect defects in the field. As a result, there is also very little if any data on how well a given inspector actually performs or the variability which can be expected between various inspectors. This comprehensive Probability of Detection (POD) study was conducted to establish the ability of an inspector with the current required training to locate cracks in steel bridge components using typical visual inspection techniques
Long Duration Head-Down Tilt Bed Rest Studies: Safety Considerations Regarding Vision Health
Visual symptoms reported in astronauts returning from long duration missions in low Earth orbit, including hyperopic shift, choroidal folds, globe flattening and papilledema, are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, safety considerations have been raised regarding the ocular health of head-down tilt (HDT) bed rest subjects. HDT is a widely used ground ]based analog that simulates physiological changes of spaceflight, including fluid shifts. Thus, vision monitoring has been performed in bed rest subjects in order to evaluate the safety of HDT with respect to vision health. Here we report ocular outcomes in 9 healthy subjects (age range: 27-48 years; Male/Female ratio: 8/1) completing bed rest Campaign 11, an integrated, multidisciplinary 70-day 6 degrees HDT bed rest study. Vision examinations were performed on a weekly basis, and consisted of office-based (2 pre- and 2 post-bed rest) and in-bed testing. The experimental design was a repeated measures design, with measurements for both eyes taken for each subject at each planned time point. Findings for the following tests were all reported as normal in each testing session for every subject: modified Amsler grid, red dot test, confrontational visual fields, color vision and fundus photography. Overall, no statistically significant differences were observed for any of the measures, except for both near and far visual acuity, which increased during the course of the study. This difference is not considered clinically relevant as may result from the effect of learning. Intraocular pressure results suggest a small increase at the beginning of the bed rest phase (p=0.059) and lesser increase at post-bed rest with respect to baseline (p=0.046). These preliminary results provide the basis for further analyses that will include correlations between intraocular pressure change pre- and post-bed rest, and optical coherence tomography measurements of the retina
The Lantern Vol. 7, No. 3, June 1939
• Commencement Sonnet • Largo Appassionato • More Sonnets to Earth • Vladimir • Abe Lincoln in Illinois • Dark Lives • Enter Mr. Smithingham II • A Character is Sketched • Sonnet • Out of the Dawn • Wistaria • Poem Without a Name • You Have Loved the Nighthttps://digitalcommons.ursinus.edu/lantern/1018/thumbnail.jp
Generalized "Quasi-classical" Ground State for an Interacting Two Level System
We treat a system (a molecule or a solid) in which electrons are coupled
linearly to any number and type of harmonic oscillators and which is further
subject to external forces of arbitrary symmetry. With the treatment restricted
to the lowest pair of electronic states, approximate "vibronic"
(vibration-electronic) ground state wave functions are constructed having the
form of simple, closed expressions. The basis of the method is to regard
electronic density operators as classical variables. It extends an earlier
"guessed solution", devised for the dynamical Jahn-Teller effect in cubic
symmetry, to situations having lower (e.g., dihedral) symmetry or without any
symmetry at all. While the proposed solution is expected to be quite close to
the exact one, its formal simplicity allows straightforward calculations of
several interesting quantities, like energies and vibronic reduction (or Ham)
factors. We calculate for dihedral symmetry two different -factors (""
and "") and a -factor. In simplified situations we obtain . The formalism enables quantitative estimates to be made for the dynamical
narrowing of hyperfine lines in the observed ESR spectrum of the dihedral
cyclobutane radical cation.Comment: 28 pages, 4 figure
Analysis by NASA's VESGEN Software of Retinal Blood Vessels Before and After 70-Day Bed Rest: A Retrospective Study
Significant risks for visual impairment associated with increased intracranial pressure (VIIP) are incurred by microgravity spaceflight, especially long-duration missions. Impairments include decreased near visual acuity, posterior globe flattening, choroidal folds, optic disc edema and cotton wool spots. We hypothesize that microgravity-induced fluid shifts result in pathological changes within the retinal blood vessels that precede development of visual and other ocular impairments. Potential contributions of retinal vascular remodeling to VIIP etiology are therefore being investigated by NASAs innovative VESsel GENeration Analysis (VESGEN) software for two studies: (1) head-down tilt in human subjects before and after 70 days of bed rest, and (2) U.S. crew members before and after ISS missions. VESGEN analysis in previous research supported by the US National Institutes of Health identified surprising new opportunities to regenerate retinal vessels during early-stage, potentially reversible progression of the visually impairing and blinding disease, diabetic retinopathy
WHOI Hawaii Ocean Timeseries Station (WHOTS) : WHOTS-3 mooring turnaround cruise report
The Woods Hole Oceanographic Institution (WHOI) Hawaii Ocean Timeseries (HOT) Site (WHOTS), 100 km north of Oahu, Hawaii,
is intended to provide long-term, high-quality air-sea fluxes as a coordinated part of the HOT program and contribute to the goals of
observing heat, fresh water, and chemical fluxes at a site representative of the oligotrophic North Pacific Ocean. The approach is to
maintain a surface mooring outfitted for meteorological and oceanographic measurements at a site near 22.75N 158W by successive
mooring turnarounds. These observations will be used to investigate air-sea interaction processes related to climate variability.
The first WHOTS mooring (WHOTS-1) was deployed in August 2004. WHOTS-1 was recovered and WHOTS-2 deployed in July 2005.
This report documents recovery of the WHOTS-2 mooring and deployment of the third mooring (WHOTS-3) at the same site. Both
moorings used Surlyn foam buoys as the surface element and were outfitted with two Air-Sea Interaction Meteorology (ASIMET)
systems. Each system measures, records, and transmits via Argos satellite, the surface meteorological variables necessary to compute
air-sea fluxes of heat, moisture, and momentum. WHOTS-2 was equipped with one Iridium data transmitter, and WHOTS-3 had two
Iridium data transmitters. In cooperation with R. Lukas of the University of Hawaii, the upper 155 m of the morrings were outfitted with
oceanographic sensors for the measurement of temperature, conductivity, and velocity.
The WHOTS mooring turnaround was done on the Scripps Institution of Oceanography ship Revelle, Cruise AMAT-07, by the Upper
Ocean Processes Group of the Woods Hole Oceanographic Institution and Roger Lukas’group at the University of Hawaii. The cruise took
place between 22 and 29 June 2006. Operations on site were initiated with an intercomparison of shipboard meteorological observations
with the WHOTS-2 buoy. Dr. Frank Bradley, CSIRO, Australia, assisted with these comparisons. This was followed by recovery of the
WHOTS-2 mooring on 24 June. A number of recovered instruments were calibrated by attaching them to the rosette frame of the CTD.
Shallow CTD profiles were taken every two hours for 12 hours on the 25th of June. A fish trap was deployed on June 25th by John Yeh, a
University of Hawaii graduate student. The WHOTS-3 mooring was deployed on 26 June at approximately 22°46'N, 157°54'W in 4703 m
of water. A ship-buoy intercomparison period and series of shallow CTDs followed along with a second deployment of the fishtrap.
A NOAA Teacher-At-Sea, Diana Griffiths, and a NOAA Hollings Scholar, Terry Smith, participated in the cruise. This report describes
the mooring operations, some of the pre-cruise buoy preparations and CTD casts taken during the cruise, the fish trap deployments, and
the experiences of the Teacher-at-Sea and Hollings Scholar.Funding was provided by the National Oceanic and Atmospheric Administration under grant No. NA17RJ1223
for the Cooperative Institute for Climate and Ocean Research (CICOR)
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