An operational satellite scatterometer for wind vector measurements over the ocean

Performance requirements and design characteristics of a microwave scatterometer wind sensor for measuring surface winds over the oceans on a global basis are described. Scatterometer specifications are developed from user requirements of wind vector measurement range and accuracy, swath width, resolution cell size and measurement grid spacing. A detailed analysis is performed for a baseline fan-beam scatterometer design, and its performance capabilities for meeting the SeaSat-A user requirements. Various modes of operation are discussed which will allow the resolution of questions concerning the effects of sea state on the scatterometer wind sensing ability and to verify design boundaries of the instrument

EFFECTOR CELL BLOCKADE : A NEW MECHANISM OF IMMUNE HYPOREACTIVITY INDUCED BY MULTIVALENT ANTIGENS

This study describes the effects of incubating antibody-forming cells (AFC), either as mass cell suspensions, or as single AFC in microdroplets, with antigens against which the cells display specificity. Most of the work was done with hapten-specific anti-DNP-AFC, but AFC with specificity against flagellar antigens or fowl gamma globulin (FGG) were also included. It was noted that 30-min incubation of AFC with highly multivalent forms of antigen caused a substantial partial suppression of the antibody-forming performance of the AFC as measured by a hemolytic plaque test. Thus, when cell suspensions containing anti-DNP plaque-forming cells (PFC), were incubated for 30 min at 37°C with 100 µg of DNP-polymerized flagellin (DNP-POL), the number of plaques appearing after washing of the cells and placing them in plaque-revealing erythrocyte monolayers was reduced to 50% or less compared with the number of plaques observed with control portions preincubated with medium alone. Preincubation with DNP-lysine, with oligovalent DNP-protein conjugates, or with irrelevant antigens produced no such inhibition. Studies where preinhibited PFC suspensions were mixed with control suspensions before assay showed that a nonspecific carryover of antigen into the assay system was not involved. The inhibitory effect could also be initiated by holding cells at 0°C with DNP-POL, but in that case, inhibition only became manifest after cells were incubated for 30 min at 37°C before being placed in plaque-revealing monolayers. This suggested that inhibition was initiated by adsorption of multivalent antigen onto PFC-surface Ig, but required some active process before secretion actually slowed down. The effect was dose- and time-dependent, antigen-specific, and generalized for all antigens studied. As well as yielding reduced plaque numbers, the preinhibited cells also gave smaller, more turbid plaques, suggesting a reduction in antibody-forming rate by each PFC rather than the elimination of PFC. Consistent with this suggestion was the observation that the degree of inhibition of plaque formation could be increased by decreasing the sensitivity of the assay so that only AFC secreting at high rates were detected. A micromanipulation study, where single PFC were subjected to inhibition, and were then tested for the rate at which they could cause hemolysis, showed a 68% inhibition of mean secretory rate. Micromanipulation studies were performed to test the amount of cell surface-associated Ig on control and preinhibited PFC. For this, single PFC were held with [125I]antiglobulin and quantitative radioautography was performed. No significant difference emerged, suggesting that retention of secreted Ig on cell-attached antigen was not the cause of inhibition. The results are discussed in the framework of tolerance models and blocking effects at the T-cell level by antigen-antibody complexes. The name effector cell blockade is suggested in the belief that the phenomenon may be a general one applying to both T and B cells

CELL-MEDIATED IMMUNE RESPONSE IN VITRO : III. THE REQUIREMENT FOR MACROPHAGES IN CYTOTOXIC REACTIONS AGAINST CELL-BOUND AND SUBCELLULAR ALLOANTIGENS

All efficient cell separation procedure and specific anti-macrophage serum were used to investigate the requirement of macrophages in the in vitro allograft response of mouse lymphoid cells. The efficiency of the macrophage-depletion procedure used and the undiminished capacity of the purified lymphocytes to respond were verified by also testing the antibody responses to sheep red cells (SRC) and dinitrophenylated polymeric flagellin (DNP POL) as well as the proliferative response to allogeneic cells. It was found that the generation of cytotoxic lymphocytes were diminished after macrophage depletion by surface adherence. The combination of anti-macrophage serum and column purification resulted in the total abolition of cytotoxic activity. The cell-mediated immune response was restored completely by addition of peritoneal macrophages, with as few as 1 macrophage to 600 lymphocytes permitting a significant restoration. Macrophages were not involved in the cytotoxic effector phase, but were essential in immune induction. A subcellular H-2 alloantigen preparation was only immunogenic in the presence of macrophages, indicating that a mere reduction in the size of the antigen from cell-bound alloantigens to membrane fragments was not the sole function of macrophages. The results suggest that macrophages collaborate with T cells in the initiation of an allograft response in vitro

Computing the local pressure in molecular dynamics simulations

Computer simulations of inhomogeneous soft matter systems often require accurate methods for computing the local pressure. We present a simple derivation, based on the virial relation, of two equivalent expressions for the local (atomistic) pressure in a molecular dynamics simulation. One of these expressions, previously derived by other authors via a different route, involves summation over interactions between particles within the region of interest; the other involves summation over interactions across the boundary of the region of interest. We illustrate our derivation using simulations of a simple osmotic system; both expressions produce accurate results even when the region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure

Large dimension Configuration Interaction calculations of positron binding to the group II atoms

The Configuration Interaction (CI) method is applied to the calculation of the structures of a number of positron binding systems, including e+Be, e+Mg, e+Ca and e+Sr. These calculations were carried out in orbital spaces containing about 200 electron and 200 positron orbitals up to l = 12. Despite the very large dimensions, the binding energy and annihilation rate converge slowly with l, and the final values do contain an appreciable correction obtained by extrapolating the calculation to the l to infinity limit. The binding energies were 0.00317 hartree for e+Be, 0.0170 hartree for e+Mg, 0.0189 hartree for e+Ca, and 0.0131 hartree for e+Sr.Comment: 13 pages, no figs, revtex format, Submitted to PhysRev

A quantum group version of quantum gauge theories in two dimensions

For the special case of the quantum group $SL_q (2,{\bf C})\ (q= \exp \pi i/r,\ r\ge 3)$ we present an alternative approach to quantum gauge theories in two dimensions. We exhibit the similarities to Witten's combinatorial approach which is based on ideas of Migdal. The main ingredient is the Turaev-Viro combinatorial construction of topological invariants of closed, compact 3-manifolds and its extension to arbitrary compact 3-manifolds as given by the authors in collaboration with W. Mueller.Comment: 6 pages (plain TeX

NASA Lunar Regolith Simulant Program

Lunar regolith simulant production is absolutely critical to returning man to the Moon. Regolith simulant is used to test hardware exposed to the lunar surface environment, simulate health risks to astronauts, practice in situ resource utilization (ISRU) techniques, and evaluate dust mitigation strategies. Lunar regolith simulant design, production process, and management is a cooperative venture between members of the NASA Marshall Space Flight Center (MSFC) and the U.S. Geological Survey (USGS). The MSFC simulant team is a satellite of the Dust group based at Glenn Research Center. The goals of the cooperative group are to (1) reproduce characteristics of lunar regolith using simulants, (2) produce simulants as cheaply as possible, (3) produce simulants in the amount needed, and (4) produce simulants to meet users? schedules

The Density of States and the Spectral Shift Density of Random Schroedinger Operators

In this article we continue our analysis of Schroedinger operators with a random potential using scattering theory. In particular the theory of Krein's spectral shift function leads to an alternative construction of the density of states in arbitrary dimensions. For arbitrary dimension we show existence of the spectral shift density, which is defined as the bulk limit of the spectral shift function per unit interaction volume. This density equals the difference of the density of states for the free and the interaction theory. This extends the results previously obtained by the authors in one dimension. Also we consider the case where the interaction is concentrated near a hyperplane.Comment: 1 figur

Excited states of positronic atoms

The existence and structure of positronic atoms with a total angular momentum of L=1 is studied with the configuration interaction method. Evidence is presented that there is a P-2(o) state of e(+)Ca and P-2,4(o) states of e(+)Be(P-3(o)) that are electronically stable with binding energies of 45 meV and 2.6 meV, respectively. These predictions rely on the use of an asymptotic series analysis to estimate the angular L ->infinity limit of the energy. Incorporating corrections that compensate for the finite range of the radial basis increased the binding energies of e(+)Ca and e(+)Be to 71 meV and 42 meV, respectively

Description, characteristics and testing of the NASA airborne radar

Presented here is a description of a coherent radar scattermeter and its associated signal processing hardware, which have been specifically designed to detect microbursts and record their radar characteristics. Radar parameters, signal processing techniques and detection algorithms, all under computer control, combine to sense and process reflectivity, clutter, and microburst data. Also presented is the system's high density, high data rate recording system. This digital system is capable of recording many minutes of the in-phase and quadrature components and corresponding receiver gains of the scattered returns for selected spatial regions, as well as other aircraft and hardware related parameters of interest for post-flight analysis. Information is given in viewgraph form