637 research outputs found
Parameter estimation supplement to the Mission Analysis Evaluation and Space Trajectory Operations program (MAESTRO)
This Parameter Estimation Supplement describes the PEST computer program and gives instructions for its use in determination of lunar gravitation field coefficients. PEST was developed for use in the RAE-B lunar orbiting mission as a means of lunar field recovery. The observations processed by PEST are short-arc osculating orbital elements. These observations are the end product of an orbit determination process obtained with another program. PEST's end product it a set of harmonic coefficients to be used in long-term prediction of the lunar orbit. PEST employs some novel techniques in its estimation process, notably a square batch estimator and linear variational equations in the orbital elements (both osculating and mean) for measurement sensitivities. The program's capabilities are described, and operating instructions and input/output examples are given. PEST utilizes MAESTRO routines for its trajectory propagation. PEST's program structure and subroutines which are not common to MAESTRO are described. Some of the theoretical background information for the estimation process, and a derivation of linear variational equations for the Method 7 elements are included
Radio astronomy Explorer-B in-flight mission control system development effort
A description is given of the development for the Mission Analysis Evaluation and Space Trajectory Operations (MAESTRO) program to be used for the in-flight decision making process during the translunar and lunar orbit adjustment phases of the flight of the Radio Astronomy Explorer-B. THe program serves two functions: performance and evaluation of preflight mission analysis, and in-flight support for the midcourse and lunar insertion command decisions that must be made by the flight director. The topics discussed include: analysis of program and midcourse guidance capabilities; methods for on-line control; printed displays of the MAESTRO program; and in-flight operational logistics and testing
Jet quenching and elliptic flow at RHIC and LHC within a pQCD-based partonic transport model
Fully dynamic simulations of heavy ion collisions at RHIC and at LHC energies
within the perturbative QCD-based partonic transport model BAMPS (Boltzmann
Approach to Multi-Parton Scatterings) are presented, focusing on the
simultaneous investigation of jet quenching and elliptic flow. The model
features inelastic 2 3 processes based on the Gunion-Bertsch matrix element
and has recently been extended to include light quark degrees of freedom,
allowing for direct comparison to hadronic data on the nuclear modification
factor via a fragmentation scheme for high-pT partons. The nuclear modification
factor of neutral pions in central Au+Au collisions at RHIC energy is compared
to experimental data. Furthermore first results on the nuclear modification
factor and the integrated elliptic flow of charged hadrons in Pb+Pb collisions
at LHC are presented and compared to recent ALICE data. These investigations
are complemented by a study on the suppression of D-mesons at LHC based on
elastic interactions with the medium.Comment: To appear in the proceedings of Quark Matter 201
Collective Flow and Mach Cones with Parton Transport
Fast thermalization and a strong build up of elliptic flow of QCD matter were
investigated within the pQCD based 3+1 dimensional parton transport model BAMPS
including bremsstrahlung processes. Within the same
framework quenching of gluonic jets in Au+Au collisions at RHIC can be
understood. The development of conical structure by gluonic jets is
investigated in a static box for the regimes of small and large dissipation.
Furthermore we demonstrate two different approaches to extract the shear
viscosity coefficient from a microscopical picture.Comment: 7 pages, 8 figures, 1 table; to appear in the proceedings of Hot and
Cold Baryonic Matter -- HCBM 201
Collective Flow and Energy Loss with parton transport
Quenching of gluonic jets and heavy quark production in Au+Au collisions at
RHIC can be understood within the pQCD based 3+1 dimensional parton transport
model BAMPS including pQCD bremsstrahlung processes.
Furthermore, the development of conical structures induced by gluonic jets is
investigated in a static box for the regimes of small and large dissipation.Comment: typos corrected, figure labels enlarged; Talk given by C. Greiner; to
appear in the proceedings of WISH201
Viscous Effects on Elliptic Flow and Shock Waves
Fast thermalization and a strong buildup of elliptic flow of QCD matter as
found at RHIC are understood as the consequence of perturbative QCD (pQCD)
interactions within the 3+1 dimensional parton cascade BAMPS. The main
contributions stem from pQCD bremsstrahlung processes.
By comparing to Au+Au data of the flow parameter as a function of
participation number the shear viscosity to entropy ratio is dynamically
extracted, which lies in the range of 0.08 and 0.2, depending on the chosen
coupling constant and freeze out condition. Furthermore, first simulations on
the temporal propagation of dissipative shock waves are given. The cascade can
either simulate true ideal shocks as well as initially diluted, truely viscous
shocks, depending on the employed cross sections or mean free path,
respectively.Comment: 7 pages, 8 figures, to appear in the proceedings of the 2008 Erice
School on Nuclear Physics, Sicil
Paper Session I-A - Is It SEP Yet?
This paper is a presentation of the results of recent studies indicating that solar electric propulsion can be implemented in a Discovery-class scenario to permit an affordable exploration of comets and asteroids in the very near future. Gallium arsenide solar array technology, the availability of space-qualified ion and plasma thrusters, and appropriate power conditioning equipment are cited as enabling factors for an exciting class of missions that can permit exploration of a number of asteroids and short-period comets, using the Delta launch vehicle, before the turn of the century. Launch requirements are about 993 kg to C$ = 10 km^/s^ for an assumed 50 to 75 kg complement of science instruments. An advantageous feature of electric propulsion is that the high installed power level, unnecessary for propulsion during rendezvous, enables high science data rates from most potential targets
Planetary benchmarks
Design criteria and technology requirements for a system of radar reference devices to be fixed to the surfaces of the inner planets are discussed. Offshoot applications include the use of radar corner reflectors as landing beacons on the planetary surfaces and some deep space applications that may yield a greatly enhanced knowledge of the gravitational and electromagnetic structure of the solar system. Passive retroreflectors with dimensions of about 4 meters and weighing about 10 kg are feasible for use with orbiting radar at Venus and Mars. Earth-based observation of passive reflectors, however, would require very large and complex structures to be delivered to the surfaces. For Earth-based measurements, surface transponders offer a distinct advantage in accuracy over passive reflectors. A conceptual design for a high temperature transponder is presented. The design appears feasible for the Venus surface using existing electronics and power components
Characterization of the monocyte-specific esterase (MSE) gene
Carboxylic esterases are widely distributed in hematopoietic cells. Monocytes express the esterase isoenzyme (termed 'monocyte-specific esterase', MSE) that can be inhibited by NaF in the alpha-naphthyl acetate cytochemical staining. We examined the expression of MSE in normal cells and primary and cultured leukemia-lymphoma cells. The MSE protein was demonstrated by isoelectric focusing (IEF); MSE mRNA expression was investigated by Northern blotting and reverse transcriptase-polymerase chain reaction (RT-PCR). The following samples were positive for MSE protein and Northern mRNA expression: 20/24 monocytic, 4/32 myeloid, and 1/20 erythroid-megakaryocytic leukemia cell lines, but none of the 112 lymphoid leukemia or lymphoma cell lines; of the normal purified cell populations only the monocytes were positive whereas, T, B cells, and granulocytes were negative; of primary acute (myelo) monocytic leukemia cells (CD14-positive, FAB M4/M5 morphology) 14/20 were Northern mRNA and 11/14 IEF protein positive. RT-PCR revealed MSE expression in 29/49 Northern-negative lymphoid leukemia-lymphoma cell lines. The RT-PCR signals in monocytic cell lines were on average 50-fold stronger than the mostly weak trace expression in lymphoid specimens. On treatment with various biomodulators, only all-trans retinoic acid significantly upregulated MSE message and protein levels but could not induce new MSE expression in several leukemia cell lines; lipopolysaccharide and interferon-gamma increased MSE expression in normal monocytes. Analysis of DNA methylation with sensitive restriction enzymes showed no apparent regulation of gene expression by differential methylation; the MSE gene is evolutionarily conserved among mammalian species; the half-life of the human MSE transcripts was about 5-6 h. The extent of MSE expression varied greatly among different monocytic leukemia samples. However, the MSE overexpression in a significant number of specimens was not associated with gene amplification, gross structural rearrangements or point mutations within the cDNA region. Taken together, the results suggest that MSE expression is not absolutely specific for, but strongly associated with cells of the monocytic lineage; MSE is either not expressed at all or expressed at much lower levels in cells from other lineages. The biological significance, if any, of rare MSE messages in lymphoid cells detectable only by the hypersensitive RT-PCR remains unclear. Further studies on the regulation of this gene and on the physiological function of the enzyme will no doubt be informative with respect to its striking overexpression in some malignant cells and to a possible role in the pathobiology of monocytic leukemias
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