81,503 research outputs found
An Analytical Investigation of Acquisition Techniques and System Integration Studies for a Radar Aircraft Guidance Research Facility
Boresight camera records for angular tracking accuracy of aircraf
Atmospheric muon background in the ANTARES detector
An evaluation of the background due to atmospheric muons in the ANTARES high
energy neutrino telescope is presented. Two different codes for atmospheric
shower simulation have been used. Results from comparisons between these codes
at sea level and detector level are presented. The first results on the
capability of ANTARES to reject this class of background are given.Comment: 4 pages, 4 figures, To appear in Proceedings of the 29th
International Cosmic Ray Conference (ICRC 2005), Pune, India, 3 - 10 Aug 200
Analysis of the financial factors governing the profitability of lunar helium-3
Financial factors influencing the profitability of the mining and utilization of lunar helium-3 are examined. The analysis addressed the following questions: (1) which financial factors have the greatest leverage on the profitability of He-3; (2) over what range can these factors be varied to keep the He-3 option profitable; and (3) what ultimate effect could this energy source have on the price of electricity for U.S. consumers. Two complementary methods of analysis were used in the assessment: rate of return on incremental investment required and reduction revenue requirements (total cost to customers) achieved. Some of the factors addressed include energy demand, power generation costs with and without fusion, profitability for D-He(3) fusion, annual capital and operating costs, launch mass and costs, He-3 price, and government funding. Specific conclusions are made with respect to each of the companies considered: utilities, lunar mining company, and integrated energy company
The credibility of health economic models for health policy decision-making: the case of population screening for abdominal aortic aneurysm
<i>Objectives</i>: To review health economic models of population screening for abdominal aortic aneurysm (AAA) among elderly males and assess their credibility for informing decision-making.
<i>Methods</i>: A literature review identified health economic models of ultrasound screening for AAA. For each model focussing on population screening in elderly males, model structure and input parameter values were critically appraised using published good practice guidelines for decision analytic models.
<i>Results</i>: Twelve models published between 1989 and 2003 were identified. Converting costs to a common currency and base year, substantial variability in cost-effectiveness results were revealed. Appraisals carried out for the nine models focusing on population screening showed differences in their complexity, with the simpler models generating results most favourable to screening. Eight of the nine models incorporated two or more simplifying structural assumptions favouring screening; uncertainty surrounding these assumptions was not investigated by any model. Quality assessments on a small number of parameters revealed input values varied between models, methods used to identify and incorporate input data were often not described, and few sensitivity analyses were reported.
<i>Conclusions</i>: Large variation exists in the cost-effectiveness results generated by AAA screening models. The substantial number of factors potentially contributing to such disparities means that reconciliation of model results is impossible. In addition, poor reporting of methods makes it difficult to identify the most plausible and thus most useful model of those developed
Locality and Translations in Braided Ribbon Networks
An overview of microlocality in braided ribbon networks is presented.
Following this, a series of definitions are presented to explore the concept of
microlocality and the topology of ribbon networks. Isolated substructure of
ribbon networks are introduced, and a theorem is proven that allows them to be
relocated. This is followed by a demonstration of microlocal translations.
Additionally, an investigation into macrolocality and the implications of
invariants in braided ribbon networks are presented.Comment: 12 pages, 12 figure
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Establishing normative values for 18-35 years age in neuropsychological tests used with head and brain injury patients during cognitive rehabilitation: Benton Visual Retention Test and National Adult Reading Test
The Benton Visual Retention Test (BVRT) is a neuropsychological assessment of visuo-spatial and visuo-memory ability. Claims of high reliability and validity are based on solitary samples representative of a wide age range. This study validated theBVRTagainst the National Adult Reading Test (NART), a highly validated and reliable test of estimated pre-morbid IQ in an age-specific group of participants (18-35 years).
Using Between-subjects factorial design, fifty-three participants (24 female, 29 male) aged 18-35 years (inclusive) were administered the NART and 3 administrations of the BVRT.
Significant positive correlations were found betweenBVRTError scores and NART Error scores for administrations B and C of theBVRTwhich is when presented stimuli are followed by a short time delay before allowing respondents to recall. Significant negative correlations were found over these administrations forBVRTCorrect scores and NART Error scores. No significant relationship was found between depression and performance on theBVRT. However, a weak, non-significant relationship was found between anxiety andBVRTperformance.
The BVRTis a well-validated and highly reliable neuropsychological test of visuo-spatial and visuo-memory abilities. Findings provide new data for the 18-35 years age group as well as providing a cautionary note on the possible influence of anxiety on performance levels in light of the frequent occurrence of anxiety post-neurological injury
An objective perspective for classic flow classification criteria
Four classic criteria used to the classification of complex flows are
discussed here. These criteria are useful to identify regions of the flow
related to shear, elongation or rigid-body motion. These usual criteria, namely
, , and , use the fluid's
rate-of-rotation tensor, which is known to vary with respect to a reference
frame. The advantages of using objective (invariant with respect to a general
transformation on the reference frame) criteria are discussed in the present
work. In this connection, we construct versions of classic criteria replacing
standard vorticity, a non-objective quantity, by effective vorticity, a rate of
rotation tensor with respect to the angular velocity of the eigenvectors of the
strain rate tensor. The classic criteria and their corresponding objective
versions are applied to classify two complex flows: the transient ABC flow and
the flow through the abrupt 4:1 contraction. It is shown that the objective
versions of the criteria provide richer information on the kinematics of the
flowComment: 11 pages, 4 figures (minor corrections and improvements
Effect of dose rate on ion beam mixing in Nb-Si
The influence of dose rate, i.e., ion flux, on ion beam mixing in Nb‐Si bilayer samples was measured at room temperature and 325 °C. At the higher temperature, an increase in dose rate of a factor of 20 caused a decrease in the thickness of the mixed layer by a factor of 1.6 for equal total doses. At room temperature, the same change in flux had no effect on mixing. These results are consistent with radiation‐enhanced diffusion theory in the recombination‐limited regime
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