6,370 research outputs found
Late follow-up after thoracic duct drainage in cadaveric renal transplantation
Thoracic duct drainage was added to conventional immunosuppression with azathioprine, prednisone and, sometimes, antilymphocyte globulin in 83 patients given cadaveric kidneys, including 65 primary graft recipients. The most effective use of thoracic duct drainage was for pretreatment. Optimal conditioning was at least four weeks duration, and when lymph drainage was this long, the incidence of rejection during the first three postoperative months was reduced to 4.5 per cent. Shorter pretreatment or institution of thoracic duct drainage contemporaneous with transplantation were less effective, but the one year results were still better than those with conventional immunosuppression alone. However, the advantage gained with thoracic duct drainage during the first year was diminished in all the treatment groups by graft losses in the second postoperative year. It was concluded that, without better maintenance therapy, the full value of temporary early lymphoid depletion procedures cannot be fully exploited
Electrically detected magnetic resonance of carbon dangling bonds at the Si-face 4H-SiC/SiO interface
SiC based metal-oxide-semiconductor field-effect transistors (MOSFETs) have
gained a significant importance in power electronics applications. However,
electrically active defects at the SiC/SiO interface degrade the ideal
behavior of the devices. The relevant microscopic defects can be identified by
electron paramagnetic resonance (EPR) or electrically detected magnetic
resonance (EDMR). This helps to decide which changes to the fabrication process
will likely lead to further increases of device performance and reliability.
EDMR measurements have shown very similar dominant hyperfine (HF) spectra in
differently processed MOSFETs although some discrepancies were observed in the
measured -factors. Here, the HF spectra measured of different SiC MOSFETs
are compared and it is argued that the same dominant defect is present in all
devices. A comparison of the data with simulated spectra of the C dangling bond
(P) center and the silicon vacancy (V) demonstrates
that the P center is a more suitable candidate to explain the
observed HF spectra.Comment: Accepted for publication in the Journal of Applied Physic
Cosmological Evolution of Supergiant Star-Forming Clouds
In an exploration of the birthplaces of globular clusters, we present a
careful examination of the formation of self-gravitating gas clouds within
assembling dark matter haloes in a hierarchical cosmological model. Our
high-resolution smoothed particle hydrodynamical simulations are designed to
determine whether or not hypothesized supergiant molecular clouds (SGMCs) form
and, if they do, to determine their physical properties and mass spectra. It
was suggested in earlier work that clouds with a median mass of several 10^8
M_sun are expected to assemble during the formation of a galaxy, and that
globular clusters form within these SGMCs. Our simulations show that clouds
with the predicted properties are indeed produced as smaller clouds collide and
agglomerate within the merging dark matter haloes of our cosmological model. We
find that the mass spectrum of these clouds obeys the same power-law form
observed for globular clusters, molecular clouds, and their internal clumps in
galaxies, and predicted for the supergiant clouds in which globular clusters
may form. We follow the evolution and physical properties of gas clouds within
small dark matter haloes up to z = 1, after which prolific star formation is
expected to occur. Finally, we discuss how our results may lead to more
physically motivated "rules" for star formation in cosmological simulations of
galaxy formation.Comment: Accepted to The Astrophysical Journal; 17 pages, 8 figure
The use of cyclosporin A and prednisone in cadaver kidney transplantation
Eighteen patients were treated with primary cadaveric renal transplantation using cyclosporin A therapy, and four more patients underwent cadaveric retransplantation. Eleven of the 22 recipients were conditioned with lymphoid depletion before transplantation, using thoracic duct drainage or lymphapheresis for two to eight and one-half weeks. cyclosporin A was begun a few hours before grafting. The other 11 patients were pretreated wtih cyclosporin A for from one day to 18 days. After transplantation, the majority of patients in both subgroups of 11 had rejection develop, but in most, the immunologic process was readily controlled with relatively small dosages of prednisone. After follow-up periods of two to four and one-half months, one patient has died of the complications of a coronary artery reconstruction that was not related to the transplantation. Another graft was lost from rejection, and a third organ was removed because of ureteral necrosis. Nineteen of the original 22 cadaveric kidneys are functioning, including 17 of the 18 kidneys given to patients who were undergoing transplantation for the first time. The only loss in the latter group of 18 patients was in the patient who died after an open heart operation. Results of these studies have shown that cyclosporin A is a superior and safe immunosuppressive drug but that, for optimal use in cadaveric transplantation, it usually should not be given alone. Steroid therapy greatly amplified the value of cyclosporin A. Unless major delayed morbidity develops which is not obvious so far, this drug combination should permit revolutionary advances ion the transplantation of all organs. Other adjunct to the cyclosporin A-steroid combination, including lymphoid depletion techniques, will require further investigation
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