Langevin Trajectories between Fixed Concentrations

We consider the trajectories of particles diffusing between two infinite baths of fixed concentrations connected by a channel, e.g. a protein channel of a biological membrane. The steady state influx and efflux of Langevin trajectories at the boundaries of a finite volume containing the channel and parts of the two baths is replicated by termination of outgoing trajectories and injection according to a residual phase space density. We present a simulation scheme that maintains averaged fixed concentrations without creating spurious boundary layers, consistent with the assumed physics

Roving vehicle motion control Final report

Roving vehicle motion control for unmanned planetary and lunar exploratio

Infusion of donor leukocytes to induce tolerance in organ allograft recipients

To further enhance chimerism, 229 primary allograft recipients have received perioperative intravenous infusion of a single dose of 3 to 6 x 108 unmodified donor bone marrow (BM) cells/kg body weight. In addition, 42 patients have been accrued in a concurrent protocol involving multiple (up to three) sequential perioperative infusions of 2 x 108 BM cells/kg/day from day 0-2 posttransplantation (PTx). Organ recipients (n = 133) for whom BM was not available were monitored as controls. The infusion of BM was safe and except for 50 (18%), all study patients have optimal graft function. Of the control patients, allografts in 30 (23%) have been lost during the course of follow-up. The cumulative risk of acute cellular rejection (ACR) was statistically lower in the study patients compared with that of controls. It is interesting that, 62% of BM-augmented heart recipients were free of ACR (Grade ≥ 3A) in the first 6 months PTx compared to controls. The incidence of obliterative bronchiolitis was also statistically lower in study lung recipients (3.8%) compared with the contemporaneously acquired controls (31%). The levels of donor cell chimerism were at least a log higher in the peripheral blood of majority of the study patients compared with that of controls. The incidence of donor-specific hyporeactivity, as determined by one-way mixed leukocyte reaction, was also higher in those BM-augmented liver, kidney, and lung recipients that could be evaluated compared to controls

Modeling the variability of the Somali Current

The dynamics of the Somali Current system during the southwest Monsoon are investigated using a 16 level general circulation model. Solutions are found for a number of model geometries and wind-forcing patterns. The first integrations reported use a model domain exactly equivalent to that of the layer model of McCreary and Kundu allowing a direct comparison between the level and layer models. In the second set of integrations a more realistic Indian Ocean geometry is used, but still with an idealized wind forcing, while in the third, the Hellerman and Rosenstein wind stresses are used to simulate the seasonal cycle. The main results are that the GCM does not easily produce the cold wedge observed in SST at ∼4N, although a current separation does develop there. A cold wedge can be produced but only if there is cold water quite close to the surface, the SST being sensitive to the vertical temperature profile. The cold wedge at ∼10N forms easily in all integrations. As the water flows offshore it slides beneath the surface giving rise to the impression that it corkscrews its way around the Great Whirl gyre. To the east, northeast, of the Great Whirl, a series of jet filaments develop, associated with strong vertical circulations. In broad outline the GCM and layer model of MK are similar, but the details of the eddy fields and coastal response are quite different. In no cases are there vacillations or gyre interactions comparable to those in the layer model