On the theory of polarization transfer in inhomogeneous magnetized plasmas

Polarization transfer theory in inhomogeneous magnetized plasmas with mode couplin

Structure of the chromosphere-corona transition region

Structure and energy distribution of chromosphere-corona transition regio

Longitude distribution of solar flares

Longitude distribution of solar flare

A simplified particulate model for coarse-grained hemodynamics simulations

Human blood flow is a multi-scale problem: in first approximation, blood is a dense suspension of plasma and deformable red cells. Physiological vessel diameters range from about one to thousands of cell radii. Current computational models either involve a homogeneous fluid and cannot track particulate effects or describe a relatively small number of cells with high resolution, but are incapable to reach relevant time and length scales. Our approach is to simplify much further than existing particulate models. We combine well established methods from other areas of physics in order to find the essential ingredients for a minimalist description that still recovers hemorheology. These ingredients are a lattice Boltzmann method describing rigid particle suspensions to account for hydrodynamic long range interactions and---in order to describe the more complex short-range behavior of cells---anisotropic model potentials known from molecular dynamics simulations. Paying detailedness, we achieve an efficient and scalable implementation which is crucial for our ultimate goal: establishing a link between the collective behavior of millions of cells and the macroscopic properties of blood in realistic flow situations. In this paper we present our model and demonstrate its applicability to conditions typical for the microvasculature.Comment: 12 pages, 11 figure

Richardson's pair diffusion and the stagnation point structure of turbulence

DNS and laboratory experiments show that the spatial distribution of straining stagnation points in homogeneous isotropic 3D turbulence has a fractal structure with dimension D_s = 2. In Kinematic Simulations the time exponent gamma in Richardson's law and the fractal dimension D_s are related by gamma = 6/D_s. The Richardson constant is found to be an increasing function of the number of straining stagnation points in agreement with pair duffusion occuring in bursts when pairs meet such points in the flow.Comment: 4 pages; Submitted to Phys. Rev. Let

A prospective randomized trial of FK506-based immunosuppression after renal transplantation

A group of 204 adult patients was entered into a prospective, randomized trial comparing FK506/pred-nisone with FK506/azathioprine/prednisone after renal transplantation between August 1, 1991 and October 11,1992. The purpose of the study was to see if the addition of azathioprine would reduce the incidence of rejection and improve graft survival. The recipient population was unselected, with 61 (30%) patients undergoing retransplantation, 37 (18%) having a panel-reactive antibody greater than 40%, and 33 (16%) over 60 years of age. The mean recipient age was 43.8±13.7 years (range 17.6-78). The mean donor age was 34.0±20.1 years (range 0.3-75); 13% of the cadaveric kidneys were from pediatric donors less than 3 years of age and were transplanted en bloc. The mean cold ischemia time was 31.4±8.4 hr. Living donors were the source of 13% of the kidneys. The mean follow-up was 22±4 months (range 12-29). Overall one-year actual patient survival was 94%. Overall one-year actual graft survival was 87%. Patients starting on double therapy had a one-year actual patient survival of 96% and a one-year actual graft survival of 92%. Patients starting on triple therapy had a one-year actual patient survival of 91% (P=ns compared with double therapy), and a one-year actual graft survival of 82% (P<0.02, compared with double therapy). Overall results with first cadaver transplants included a one-year actual patient survival of 94% and one-year actual graft survival of 88%, with no differences between double and triple therapy. The overall incidence of rejection was 48%, with 54% in the double therapy group and 41% in the triple therapy group (P<.07). The incidence of steroid-resistant rejection requiring antilymphocyte therapy (OKT3 or ATGAM) was 13%, and was not different between the double and triple therapy groups. The mean serum creatinine was 1.8±0.8 mg/dl. The mean BUN was 33±21 mg/dl, with no significant difference between the therapy groups. The mean serum cholesterol was 192 ±49 mg/dl. A total of 56% of the patients are off prednisone, and 35% of the patients are not taking any antihypertensive medications. Other complications included cytomegalovirus—14%; new-onset diabetes—16% (half of which was reversible); and posttransplant lymphoproliferative disorder—1%. There was a high incidence of crossover between the two groups, 27% of the patients in the double therapy group requiring the addition of azathioprine, and 45% of the patients in the triple therapy group requiring its discontinuation (usually tempoгагу). These results show that FK506 is an excellent immunosuppressive agent after renal transplantation and that azathioprine is not routinely effective as a third agent. A high quality of life resulted from the ability to use no (56%) or low-dose maintenance steroids. © 1995 by Williams and Wilkins

Measured and Calculated Dynamic Response of Rock-Fill Dam

The U.S. Army Corps of Engineers recently completed a seismic stability assessment of the Ririe Darn and Reservoir Project located near Idaho Falls, Idaho. Ririe Darn is an earth- and rockfill darn with a central impervious core constructed between 1966 and 1975 in a narrow canyon of Willow Creek. A geologic and seismologic study indicated that the controlling maximum credible earthquake (MCE} is a Magnitude 7.5 earthquake at a distance of 8 km from the darn. The seismic stability analysis included a dynamic response analysis of the darn using two-dimensional finite element procedures. Empirical relations derived from the observed response and analyses of other darns in narrow canyons were used to develop adjustment factors to correct natural frequencies, dynamic shear stresses, and peak accelerations for three-dimensional (3-D} effects. The October 28, 1983 Mt. Borah Earthquake triggered five strong-motion instruments installed at the crest, left abutment, downstream toe, and outlet tower of Ririe Darn. The epicentral distance to the darn was 179 km. The peak horizontal accelerations recorded at the crest and at the abutment were 0.05 g and 0.02 g, respectively. The accelerogram recorded by the instrument station at the abutment was used to calculate the dynamic response of the darn during the earthquake. From this analysis, the finite element model and the soil parameters were calibrated to best represent the 3-D dynamic response of the darn. After consideration of 3-D effects, the calculated response of the darn using soil properties derived from in-situ and laboratory measurements was in good agreement with the measured response during the 1983 Mt. Borah earthquake. These results indicate that when properly applied, currently available methods to determine soil properties for the dynamic response analysis of embankment darns including in-situ measurements, can provide properties in good agreement with those back-calculated from the observed response of darns

Skylab S-193 Radscat microwave measurements of sea surface winds

The S-193 Radscat made extensive measurements of many sea conditions. Measurements were taken in a tropical hurricane (Ava), a tropical storm (Christine), and in portions of extratropical cyclones. Approximately 200 scans of ocean data at 105 kilometer spacings were taken during the first two Skylab missions and another 200 during the final mission when the characteristics of the measurements changed due to damage of the antenna. Backscatter with four transmit/receive polarization combinations and emissions with horizontal and vertical receive polarizations were measured. Other surface parameters investigated for correlation with the measurements included sea temperature, air/sea temperature difference, and gravity-wave spectrum. Methods were developed to correct the microwave measurements for atmospheric effects. The radiometric data were corrected accurately for clear sky and light cloud conditions only. The radiometer measurements were used to recover the surface scattering characteristics for all atmospheric conditions excluding rain. The radiometer measurements also detected the presence of rain which signaled when the scattering measurement should not be used for surface wind estimation. Regression analysis was used to determine empirically the relation between surface parameters and the microwave measurements, after correction for atmospheric effects. Results indicate a relationship approaching square-law at 50 deg between differential scattering coefficient and wind speed with horizontally polarized scattering data showing slightly more sensitivity to wind speed than vertically polarized data

Geometrical dependence of low frequency noise in superconducting flux qubits

A general method for directly measuring the low-frequency flux noise (below 10 Hz) in compound Josephson junction superconducting flux qubits has been used to study a series of 85 devices of varying design. The variation in flux noise across sets of qubits with identical designs was observed to be small. However, the levels of flux noise systematically varied between qubit designs with strong dependence upon qubit wiring length and wiring width. Furthermore, qubits fabricated above a superconducting ground plane yielded lower noise than qubits without such a layer. These results support the hypothesis that localized magnetic impurities in the vicinity of the qubit wiring are a key source of low frequency flux noise in superconducting devices.Comment: 5 pages, 5 figure