2,518 research outputs found
Magnetic bearing turbomachinery case histories and applications for space related equipment
The concept of magnetic levitation is not a new one and can be easily traced back to the 1800's. It is only recently, however, that the congruous technologies of electronic control systems, power electronics, and magnetic materials have begun to merge to make the magnetic suspension device a viable product. A brief overview of an active magnetic bearing technology is provided. Case histories of various turbomachinery in North America presently operating on magnetic bearings are reviewed. Finally, projections are made as to the space related machinery that may be benefited by incorporating magnetic bearings into the equipment design
Thermal Dileptons from Quark and Hadron Phases of an Expanding Fireball
A fireball model with time evolution based on transport calculations is used
to examine the dilepton emission rate of an ultra-relativistic heavy-ion
collision. We assume a transition from hadronic matter to a quark-gluon plasma
at a critical temperature T_C between 130-170 MeV. We include thermal
corrections to the hadronic spectra below T_C and use perturbation theory above
T_C. The sensitivity of the spectra with respect to the freeze-out temperature,
the initial fireball temperature and the critical temperature is investigated.Comment: 14 pages, 5 figures; paragraph and one figure added; version to
appear in Eur. Phys. J.
Strange magnetic moment of the nucleon and SU(3) breaking: group theoretical approach
An extended group-theoretical approach to magnetic moments of the octet
baryons is proposed with the aim of extracting the strange magnetic moment of
the nucleon. Special attention is given to flavor SU(3) breaking. In this
approach, isoscalar and isovector magnetic moments are treated separately in
view of their different behavior under SU(3) breaking. We conclude that the
anomalous magnetic moment associated with the flavor singlet current is small.
Together with the small isoscalar anomalous magnetic moment of the nucleon,
this implies suppression of the strange magnetic moment of the proton which is
found to be small and positive, mu^(s) = (0.16 \pm 0.03) mu_N in units of the
nuclear magneton.Comment: 6 pages, no figure, 6 tables, use REVTeX
Effective Kbar N interaction based on chiral SU(3) dynamics
The effective Kbar N interaction based on chiral SU(3) coupled-channel
dynamics is derived and its extrapolation below the Kbar N threshold is studied
in detail. Starting from the coupled-channel scattering equations, we eliminate
the channels other than Kbar N and obtain an effective interaction in the
single Kbar N channel. An equivalent local potential in coordinate space is
constructed such as to reproduce the full scattering amplitude of the chiral
SU(3) coupled-channel framework. We discuss several realistic chiral
SU(3)-based models in comparison to reach conclusions about the uncertainties
involved. It turns out that, in the region relevant to the discussion of deeply
bound Kbar-nuclear few-body systems, the resulting energy-dependent, equivalent
local potential is substantially less attractive than the one suggested in
previous purely phenomenological treatments.Comment: RevTeX4, 16 pages, 15 figures, 5 tables, effect of higher order terms
is discussed, final version to appear in Phys. Rev.
Model for dilepton rates from a fireball
We calculate the dilepton emission rate from a fireball created in an
ultra-relativistic heavy-ion collision. For the partonic phase, we complement
the perturbative results by a phenomenological approach based on lattice QCD
results, whereas in the hadronic phase temperature and finite baryon density
effects on the spectral function are considered. The resulting rates are
compared to data from CERES/NA45.Comment: 4 pages, 3 figures. Talk given at 15th International Conference on
Ultrarelativistic Nucleus-Nucleus Collisions (QM2001), Stony Brook, New York,
15-20 Jan 200
Weekly irinotecan in a patient with metastatic colorectal cancer on hemodialysis due to chronic renal failure
Background: The cytotoxic treatment of patients suffering from advanced or metastatic cancer undergoing hemodialysis due to chronic renal failure still remains a problem, since for those patients pharmacokinetic and pharmacodynamic data on most cytotoxic agents are lacking. Case Report: We report a 45-year-old male who suffered from chronic renal failure and was diagnosed with stage-3 colorectal cancer (CRC) in February 2000. After surgical removal of the tumor an adjuvant chemotherapy of dose-reduced i.v. bolus 5-fluorouracil and folinic acid was begun (Mayo protocol). Due to excessive gastrointestinal toxicity, therapy was discontinued after the first cycle. In April 2000 liver metastases were diagnosed. The patient was then put on a weekly schedule of dose-reduced CPT-11 (50 mg/m(2), 80 mg total). No hematological or non-hematological toxicity grade 3/4 was observed. Due to excellent tolerability and lack of severe side effects the dose was increased up to 80 mg/m2 (140 mg total) weekly. A dose escalation to 100 mg/m(2) (180 mg total) resulted in severe diarrhea (grade 4). Within 2 months of treatment the patient achieved a lasting partial remission until April 2001 (12 months). A significant progression of hepatic metastases required an alternative treatment regimen beginning in July 2001 (HAI, hepatic artery infusion). Conclusion: This case report demonstrates the feasibility and efficacy of a weekly treatment with dose-reduced CPT-11 in a patient with metastatic CRC on hemodialysis due to chronic renal failure
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