Evaluation of a pulsed quasi-steady MPD thruster and associated subsystems

The performance of quasi-steady magnetoplasmadynamic (MPD) thrusters at high power levels is discussed. An axisymmetric configuration is used for the MPD thruster, with various cathode and anode sizes, over a wide range of experimental conditions. Thrust is determined from impulse measurements with current waveforms, while instantaneous measurements are made for all other variables. It is demonstrated that the thrust produced has a predominately self-magnetic origin and is directly proportional to the square of the current. The complete set of impulse measurement data is presented

Quasi-steady MPD propulsion at high power Final technical report

Quasi-steady MPD propulsion at power levels in range 1 to 10 megawatt

Report of conference evaluation committee

A general classification is made of a number of approaches used for the prediction of turbulent shear flows. The sensitivity of these prediction methods to parameter values and initial data are discussed in terms of variable density, pressure fluctuation, gradient diffusion, low Reynolds number, and influence of geometry

Dissipation enhanced vibrational sensing in an olfactory molecular switch

Motivated by a proposed olfactory mechanism based on a vibrationally-activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (Marcus-Jortner) rate analyses. We show: (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electron transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, are enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters.Comment: 12 pages, 6 figures, close to published version, comments welcom

Coefficient Functions and Open Charm Production in Deep Inelastic Scattering

It is shown that the problem of double counting in open charm production in DIS can be solved by using the expression for DIS coefficient functions in terms of 2PI diagramsComment: 11 pages, REVTeX, no figure

Adenovirus-mediated gene transfer into normal rabbit arteries results in prolonged vascular cell activation, inflammation, and neointimal hyperplasia

Adenovirus vectors are capable of high efficiency in vivo arterial gene transfer, and are currently in use as therapeutic agents in animal models of vascular disease. However, despite substantial data on the ability of viruses to cause vascular inflammation and proliferation, and the presence in current adenovirus vectors of viral open reading frames that are translated in vivo, no study has examined the effect of adenovirus vectors alone on the arterial phenotype. In a rabbit model of gene transfer into a normal artery, we examined potential vascular cell activation, inflammation, and neointimal proliferation resulting from exposure to replication-defective adenovirus. Exposure of normal arteries to adenovirus vectors resulted in: (a) pronounced infiltration of T cells throughout the artery wall; (b) upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in arterial smooth muscle cells; (c) neointimal hyperplasia. These findings were present both 10 and 30 d after gene transfer, with no evidence of a decline in severity over time. Adenovirus vectors have pleiotropic effects on the arterial wall and cause significant pathology. Interpretation of experimental protocols that use adenovirus vectors to address either biological or therapeutic issues should take these observations into account. These observations should also prompt the design of more inert gene transfer vectors