3,915 research outputs found
Incorporation of fullerene-C60 and C60-adducts in micellar and vesicular supramolecular assemblies; Introductory flash photolysis and photoredox experiments in micelles
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A comparative assessment of the economics of plutonium disposition
The US Department of Energy office of Fissile Materials Disposition (DOE/MD) has been evaluating three technologies for the disposition of approximately 50 metric tons of surplus plutonium from defense-related programs: reactors, immobilization, and deep boreholes. As part of the process supporting an early CY 1997 Record of Decision (ROD), a comprehensive assessment of technical viability, cost, and schedule has been conducted by DOE/MD and its national laboratory contractors. Oak Ridge National Laboratory has managed and coordinated the life-cycle cost (LCC) assessment effort for this program. This paper discusses the economic analysis methodology and the results prior to ROD. A secondary intent of the paper is to discuss major technical and economic issues that impact cost and schedule. To evaluate the economics of these technologies on an equitable basis, a set of cost-estimating guidelines and a common cost-estimating format were utilized by all three technology teams. This paper also includes the major economic analysis assumptions and the comparative constant-dollar and discounted-dollar LCCs
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A comparative assessment of the economics of plutonium disposition including comparison with other nuclear fuel cycles
DOE has been evaluating three technologies for the disposition of approximately 50 metric tons of surplus plutonium from defense-related programs: reactors, immobilization, and deep boreholes. As part of the process supporting an early CY 1997 Record of Decision (ROD), a comprehensive assessment of technical viability, cost, and schedule has been conducted. Oak Ridge National Laboratory has managed and coordinated the life-cycle cost (LCC) assessment effort for this program. This paper discusses the economic analysis methodology and the results prior to ROD. Other objectives of the paper are to discuss major technical and economic issues that impact plutonium disposition cost and schedule. Also to compare the economics of a once-through weapons-derived MOX nuclear fuel cycle to other fuel cycles, such as those utilizing spent fuel reprocessing. To evaluate the economics of these technologies on an equitable basis, a set of cost estimating guidelines and a common cost-estimating format were utilized by all three technology teams. This paper also includes the major economic analysis assumptions and the comparative constant-dollar and discounted-dollar LCCs
Cardiovascular risk assessments at occupational health services: employee experiences
Background:
Across England in the UK, population screening for cardiovascular disease (CVD) primarily takes place within general practice in the form of the National Health Service Health Check. Additional screening sites such as occupational health are advocated to improve the population impact.
Aims:
To investigate participant experiences with cardiovascular and type 2 diabetes risk assessment (RA) at occupational health and subsequent support-seeking at general practice.
Methods:
Face-to-face interviews were conducted for this qualitative study. Participants were recruited at three workplaces; a steel works and two hospital sites. Using interpretive phenomenological analyses, themes were drawn from salient narratives and categorically organized.
Results:
There were 29 participants. Themes (n = 16) were organized into two domains; factors that facilitated (n = 9) or thwarted (n = 7) participant engagement with the RA and general practice. All participants described the RA as worthwhile and strongly valued RA at occupational health. Those with obesity and high CVD risk highlighted their difficulties in making lifestyle changes. Participants reported confusion and anxiety when GP advice about medication appeared to contradict what participants had interpreted during RA at occupational health.
Conclusions:
This study highlights factors that facilitate or thwart engagement in cardiovascular RA at occupational health services and general practice follow-up. Stakeholders can integrate these factors into standard operating procedures to enhance participant engagement and enable safeguards that minimize potential harm to participants
Gender differences in the prevalence of impaired fasting glycaemia and impaired glucose tolerance in Mauritius. Does sex matter?
Objective: To examine gender differences in the characteristics and prevalence of various categories of glucose tolerance in a population study in Mauritius.Research design and methods: In 1998, a community-based cross-sectional survey was conducted in Mauritius. Categories of glucose metabolism were determined in 5388 adults, with an oral glucose tolerance test given to those who did not have previously diagnosed diabetes (n = 4036). Other cardiovascular risk factors were assessed among those without known diabetes.Results: For men and women the prevalence of diabetes (22.0 vs. 21.8%, respectively) and the prevalence of coexisting impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) (3.2 vs. 2.9%) were similar. However, men were twice as likely as women to have isolated IFG [5.1% (4.2–6.0) vs. 2.9% (2.3–3.5)], despite being younger, thinner and with lower plasma insulin but higher lipids. Conversely, the prevalence of isolated IGT was lower in men [9.0% (7.9–10.2) vs. 13.9% (12.6–15.1)]. Among non-diabetic individuals, fasting glucose was higher in men than women, whereas 2-h glucose was higher in women. In people without diabetes, women had significantly higher body mass index, beta cell function (HOMA-B), fasting and 2-h insulin than men and significantly lower waist-hip ratios, waist circumference, insulin sensitivity (HOMA-S) and triglycerides.Conclusion: In Mauritius, the distribution of impaired glucose metabolism differs by sex. The observation that IFG is more prevalent in men and IGT more prevalent in women raises important questions about their underlying aetiology and the ability of the current glucose thresholds to equally identify men and women at high-risk of developing diabetes. IFG should be seen as a complimentary category of abnormal glucose tolerance, rather than a replacement for IGT.<br /
Synthesis effects on the magnetic and superconducting properties of RuSr2GdCu2O8
A systematic study on the synthesis of the Ru-1212 compound by preparing a
series of samples that were annealed at increasing temperatures and then
quenched has been performed. It results that the optimal temperature for the
annealing lies around 1060-1065 C; a further temperature increase worsens the
phase formation. Structural order is very important and the subsequent grinding
and annealing improves it. Even if from the structural point of view the
samples appear substantially similar, the physical characterization highlight
great differences both in the electrical and magnetic properties related to
intrinsic properties of the phase as well as to the connection between the
grains as inferred from the resistive and the Curie Weiss behaviour at high
temperature as well as in the visibility of ZFC anf FC magnetic signals.Comment: 17 pages, 12 figures. Proc. Int. Workshop " Ruthenate and
rutheno-cuprate materials: theory and experiments", Vietri, October 2001. To
be published on LNP Series, Springer Verlag, Berlin, C. Noce, A. Vecchione,
M. Cuoco, A. Romano Eds, 200
A Quantum-Mechanical Equivalent-Photon Spectrum for Heavy-Ion Physics
In a previous paper, we calculated the fully quantum-mechanical cross section
for electromagnetic excitation during peripheral heavy-ion collisions. Here, we
examine the sensitivity of that cross section to the detailed structure of the
projectile and target nuclei. At the transition energies relevant to nuclear
physics, we find the cross section to be weakly dependent on the projectile
charge radius, and to be sensitive to only the leading momentum-transfer
dependence of the target transition form factors. We exploit these facts to
derive a quantum-mechanical ``equivalent-photon spectrum'' valid in the
long-wavelength limit. This improved spectrum includes the effects of
projectile size, the finite longitudinal momentum transfer required by
kinematics, and the response of the target nucleus to the off-shell photon.Comment: 19 pages, 5 figure
A Lattice Study of the Magnetic Moment and the Spin Structure of the Nucleon
Using an approach free from momentum extrapolation, we calculate the nucleon
magnetic moment and the fraction of the nucleon spin carried by the quark
angular momentum in the quenched lattice QCD approximation. Quarks with three
values of lattice masses, 210, 124 and 80 MeV, are formulated on the lattice
using the standard Wilson approach. At every mass, 100 gluon configurations on
16^3 x 32 lattice with \beta=6.0 are used for statistical averaging. The
results are compared with the previous calculations with momentum
extrapolation. The contribution of the disconnected diagrams is studied at the
largest quark mass using noise theory technique.Comment: 14 pages, 3 figures, Talk given at Lattice2001, Berlin, German
Evidence for Possible Phase-Separations in RuSr2(Gd,Ce)2Cu2O10-delta
An unusual thermal-magnetic hysteresis was observed between a minor magnetic
transition around 120 K and the main one at 80 K in superconducting
RuSr2(R,Ce)2Cu2O10-delta (Ru1222R) samples, where R = Gd or Eu, down to a
submicron length-scale. The observation suggests a possible phase-separation
and is consistent with the very small but universal demagnetizing factor
observed, which is difficult to reconcile with the canted spin-structure
previously proposed. In such a scenario, the unusual superconducting properties
of the Ru-based cuprates can also be understood naturally.Comment: 8 pages, 3 figures, submitted to Phys. Rev. B, "Rapid Communications"
(September 26, 2001
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