Serum Levels of Rubella Virus Antibodies Indicating Immunity: Response to Vaccination of Subjects with Low or Undetectable Antibody Concentrations

To define the concentration of anti-rubella virus (RV) antibodies discriminating nonimmune from immune persons and to characterize immune responses to rubella vaccination, serologic studies were performed after rubella vaccination in persons with low or undetectable antibody concentrations. Thirty-six subjects with primary immune responses had prevaccination anti-RV IgG concentrations 2 weeks and thus resembled the time course of primary immunization, but IgM responses and IgG avidity were distinct between subjects with primary or secondary immune responses. Thresholds for immunity <15 IU/mL entail the risk of withholding rubella vaccination from susceptible person

Xenon Excimer Emission From Pulsed Microhollow Cathode Discharges

By applying electrical pulses of 20 ns duration to xenon microplasmas, generated by direct current microhollow cathode discharges, we were able to increase the xenon excimer emission by more than an order of magnitude over direct current discharge excimer emission. For pulsed voltages in excess of 500 V, the optical power at 172 nm was found to increase exponentially with voltage. Largest values obtained were 2.75 W of vacuum-ultraviolet optical power emitted from a single microhollow cathode discharge in 400 Torr xenon with a 750 V pulse applied to a discharge. Highest radiative emittance was 15.2 W/cm2. The efficiency for excimer emission was found to increase linearly with pulsed voltages above 500 V reaching values of 20% at 750 V

Resonant Energy Transfer From Argon Dimers to Atomic Oxygen in Microhollow Cathode Discharges

The emission of atomic oxygen lines at 130.2 and 130.5 nm from a microhollow cathode discharge in argon with oxygen added indicates resonant energy transfer from argon dimers to oxygen atoms. The internal efficiency of the vacuum-ultraviolet (VUV) radiation was measured as 0.7% for a discharge in 1100 Torr argon with 0.1% oxygen added. The direct current VUV point source operates at voltages below 300 V and at current levels of milliamperes

PIV-based dynamic model of EHD volume force produced by a surface dielectric barrier discharge

In this paper, an experimental measurement of the f low produced by a surface DBD plasma actuator has been conducted. One original aspect of these measurements by particle image velocimetry is the high acquisition rate for a PIV system (20 kHz). By using these highly- resolved flow measurements, the fluid flow velocity is used to estimate the spatial and temporal evolution of the EHD volume force. A reduced order model of this force has been constructed by proper orthogonal decomposition. Based on the analy sis of the time-resolved expansion coefficients and their associated spatial modes, it is shown that the volume force can be reconstructed by using a limited number of POD mode s (6 modes). This spatial and temporal filtering of the force fields remains faithful to t he original data and it will help in view of an implementation of such a source term in a numerical solver. The resulting dynamic model shows an alternation of positive and negative volume forc es. The strong positive EHD force developing in the glow regime of the DBD plasma discharge is v isualized in a time-resolved manner. This positive force is immediately followed by a strong negative volume force probably caused by the local flow deceleration

Hydrographic and nutrient data from R/V Knorr cruise 73, leg 2 : February to March, 1978 : off the coast of Peru

In February and March of 1978 a major cruise was undertaken on the R/V KNORR off the Peruvian coast near 15°S in order to investigate the organic biogeochemical processes associated with upwelling areas. The purpose of this report is to collate the large amount of hydrographic, nutrient, and plankton data generated from various investigators on this cruise and use the report as a standard for the cruise participants. Data for temperature, salinity, oxygen, nitrate, nitrite, ammonium, phosphate, silicate, chlorophyll a, productivity indices, and carbon fixation rates are given.Prepared for the National Science Foundation under Grant OCE 77-26084, for the Office of Naval Research under Contract N00014-74-C-0262 ER 083-004 and for the NOAA Office of Sea Grant under Grants 04-7-158-44034 and 04-8-MO1-79 to the University of New Hampshire/University of Maine Cooperative Institutional Sea Grant Proqram

Inception and propagation of positive streamers in high-purity nitrogen: effects of the voltage rise-rate

Controlling streamer morphology is important for numerous applications. Up to now, the effect of the voltage rise rate was only studied across a wide range. Here we show that even slight variations in the voltage rise can have significant effects. We have studied positive streamer discharges in a 16 cm point-plane gap in high-purity nitrogen 6.0, created by 25 kV pulses with a duration of 130 ns. The voltage rise varies by a rise rate from 1.9 kV/ns to 2.7 kV/ns and by the first peak voltage of 22 to 28 kV. A structural link is found between smaller discharges with a larger inception cloud caused by a faster rising voltage. This relation is explained by the greater stability of the inception cloud due to a faster voltage rise, causing a delay in the destabilisation. Time-resolved measurements show that the inception cloud propagates slower than an earlier destabilised, more filamentary discharge. This explains that the discharge with a faster rising voltage pulse ends up to be shorter. Furthermore, the effect of remaining background ionisation in a pulse sequence has been studied, showing that channel thickness and branching rate are locally affected, depending on the covered volume of the previous discharge.Comment: 16 pages, 9 figure

Wall charge and potential from a microscopic point of view

Macroscopic objects floating in an ionized gas (plasma walls) accumulate electrons more efficiently than ions because the influx of electrons outruns the influx of ions. The floating potential acquired by plasma walls is thus negative with respect to the plasma potential. Until now plasma walls are typically treated as perfect absorbers for electrons and ions, irrespective of the microphysics at the surface responsible for charge deposition and extraction. This crude description, sufficient for present day technological plasmas, will run into problems in solid-state based gas discharges where, with continuing miniaturization, the wall becomes an integral part of the plasma device and the charge transfer across it has to be modelled more precisely. The purpose of this paper is to review our work, where we questioned the perfect absorber model and initiated a microscopic description of the charge transfer across plasma walls, put it into perspective, and indicate directions for future research.Comment: 8 pages, 5 figures, submitted to the Contributions to Plasma Physics' special issue "Progress in complex plasmas

Effects of particle size on CO2 reduction and discharge characteristics in a packed bed plasma reactor

Current understanding of the behaviour of plasma discharges within packed bed reactors (PBRs) is very poor, and the effects of many of the parameters that can be varied are still unknown. This article investigates the effects of particle size (180 μm to 2000 μm) of two different commonly used packing materials (Al2O3 and BaTiO3) on the conversion of CO2 in PBRs. The reactor behaviour is observed through determination of product gas composition and plasma power consumption in order to determine CO2 conversion and reactor efficiency. Electrical characterisation techniques are used to determine reactor burning voltage, and capacitances. These capacitances are subsequently used to quantify the occurrence of reactor partial discharging over a range of different operating conditions. The results indicate that smaller particles (down to 180 μm) can significantly increase CO2 conversion by up to 70%, provided that the voltage applied is sufficiently high to generate a discharge in the void spaces of the packing material. However, with decreasing particle size, the reactor burning voltage is found to increase rapidly, as well as the tendency of the reactor towards partial discharging