14,442 research outputs found
Study of zero-gravity, vapor/liquid separators
Heat exchange, mechanical separation, surface tension, and dielectrophoretic methods of separating vapor from liquid at zero gravity for vapor ventin
Gene-history correlation and population structure
Correlation of gene histories in the human genome determines the patterns of
genetic variation (haplotype structure) and is crucial to understanding genetic
factors in common diseases. We derive closed analytical expressions for the
correlation of gene histories in established demographic models for genetic
evolution and show how to extend the analysis to more realistic (but more
complicated) models of demographic structure. We identify two contributions to
the correlation of gene histories in divergent populations: linkage
disequilibrium, and differences in the demographic history of individuals in
the sample. These two factors contribute to correlations at different length
scales: the former at small, and the latter at large scales. We show that
recent mixing events in divergent populations limit the range of correlations
and compare our findings to empirical results on the correlation of gene
histories in the human genome.Comment: Revised and extended version: 26 pages, 5 figures, 1 tabl
Spectroscopy of a synthetic trapped ion qubit
has been identified as an attractive ion for quantum
information processing due to the unique combination of its spin-1/2 nucleus
and visible wavelength electronic transitions. Using a microgram source of
radioactive material, we trap and laser-cool the synthetic = 133
radioisotope of barium II in a radio-frequency ion trap. Using the same, single
trapped atom, we measure the isotope shifts and hyperfine structure of the and
electronic transitions that are needed
for laser cooling, state preparation, and state detection of the clock-state
hyperfine and optical qubits. We also report the
electronic transition isotope shift for
the rare = 130 and 132 barium nuclides, completing the spectroscopic
characterization necessary for laser cooling all long-lived barium II isotopes
Recertification of the air and methane storage vessels at the Langley 8-foot high-temperature structures tunnel
This center operates a number of sophisticated wind tunnels in order to fulfill the needs of its researchers. Compressed air, which is kept in steel storage vessels, is used to power many of these tunnels. Some of these vessels have been in use for many years, and Langley is currently recertifying these vessels to insure their continued structural integrity. One of the first facilities to be recertified under this program was the Langley 8-foot high-temperature structures tunnel. This recertification involved (1) modification, hydrotesting, and inspection of the vessels; (2) repair of all relevant defects; (3) comparison of the original design of the vessel with the current design criteria of Section 8, Division 2, of the 1974 ASME Boiler and Pressure Vessel Code; (4) fracture-mechanics, thermal, and wind-induced vibration analyses of the vessels; and (5) development of operating envelopes and a future inspection plan for the vessels. Following these modifications, analyses, and tests, the vessels were recertified for operation at full design pressure (41.4 MPa (6000 psi)) within the operating envelope developed
Process of designing robust, dependable, safe and secure software for medical devices: Point of care testing device as a case study
This article has been made available through the Brunel Open Access Publishing Fund.Copyright © 2013 Sivanesan Tulasidas et al. This paper presents a holistic methodology for the design of medical device software, which encompasses of a new way of eliciting requirements, system design process, security design guideline, cloud architecture design, combinatorial testing process and agile project management. The paper uses point of care diagnostics as a case study where the software and hardware must be robust, reliable to provide accurate diagnosis of diseases. As software and software intensive systems are becoming increasingly complex, the impact of failures can lead to significant property damage, or damage to the environment. Within the medical diagnostic device software domain such failures can result in misdiagnosis leading to clinical complications and in some cases death. Software faults can arise due to the interaction among the software, the hardware, third party software and the operating environment. Unanticipated environmental changes and latent coding errors lead to operation faults despite of the fact that usually a significant effort has been expended in the design, verification and validation of the software system. It is becoming increasingly more apparent that one needs to adopt different approaches, which will guarantee that a complex software system meets all safety, security, and reliability requirements, in addition to complying with standards such as IEC 62304. There are many initiatives taken to develop safety and security critical systems, at different development phases and in different contexts, ranging from infrastructure design to device design. Different approaches are implemented to design error free software for safety critical systems. By adopting the strategies and processes presented in this paper one can overcome the challenges in developing error free software for medical devices (or safety critical systems).Brunel Open Access Publishing Fund
The Unpredictability of the Most Energetic Solar Events
Observations over the past two solar cycles show a highly irregular pattern
of occurrence for major solar flares, gamma-ray events, and solar energetic
particle (SEP) fluences. Such phenomena do not appear to follow the direct
indices of solar magnetic activity, such as the sunspot number. I show that
this results from the non-Poisson occurrence for the most energetic events.
This Letter also points out a particularly striking example of this
irregularity in a comparison between the declining phases of the recent two
solar cycles (1993-1995 and 2004-2006, respectively) and traces it through the
radiated energies of the flares, the associated SEP fluences, and the sunspot
areas. These factors suggest that processes in the solar interior involved with
the supply of magnetic flux up to the surface of the Sun have strong
correlations in space and time, leading to a complex occurrence pattern that is
presently unpredictable on timescales longer than active region lifetimes
(weeks) and not correlated well with the solar cycle itself.Comment: 4 page
Modeling Solar Lyman Alpha Irradiance
Solar Lyman alpha irradiance is estimated from various solar indices using linear regression analyses. Models developed with multiple linear regression analysis, including daily values and 81-day running means of solar indices, predict reasonably well both the short- and long-term variations observed in Lyman alpha. It is shown that the full disk equivalent width of the He line at 1083 nm offers the best proxy for Lyman alpha, and that the total irradiance corrected for sunspot effect also has a high correlation with Lyman alpha
Coccidia (Apicomplexa: Eimeriidae) of Three-toed Box Turtles, Terrapene carolina triunguis (Reptilia: Testudines), from Arkansas and Oklahoma
We collected 50 three-toed box turtles (Terrapene carolina triunguis) from 9 counties of Arkansas and 4 counties of Oklahoma, and examined their feces for coccidial parasites. Nine of 24 (38%) turtles from Arkansas and 8 of 26 (31%) from Oklahoma were found to be passing oocysts of Eimeria ornata. This represents two new geographic distributional records for this coccidian. Measurements of individual isolates of E. ornate as well as morphological characteristics are provided with comparison to its original description and to another Terrapene coccidian, Eimeria carri. In addition, we noted an adelid pseudoparasite being passed by a single T. c. triunguis from Oklahoma that likely represents a parasite of arthropods
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