23,323 research outputs found
Surveyor lunar touchdown stability study Final report, Jul. 1965 - Jul. 1966
Dynamic analysis and computer simulation of Surveyor lunar landing stabilit
PeV-Scale Supersymmetry
Although supersymmetry has not been seen directly by experiment, there are
powerful physics reasons to suspect that it should be an ingredient of nature
and that superpartner masses should be somewhat near the weak scale. I present
an argument that if we dismiss our ordinary intuition of finetuning, and focus
entirely on more concrete physics issues, the PeV scale might be the best place
for supersymmetry. PeV-scale supersymmetry admits gauge coupling unification,
predicts a Higgs mass between 125 GeV and 155 GeV, and generally disallows
flavor changing neutral currents and CP violating effects in conflict with
current experiment. The PeV scale is motivated independently by dark matter and
neutrino mass considerations.Comment: 5 RevTex page
Altered muscarinic and nicotinic receptor densities in cortical and subcortical brain regions in Parkinson's disease
Muscarinic and nicotinic cholinergic receptors and choline acetyltransferase activity were studied in postmortem brain tissue from patients with histopathologically confirmed Parkinson's disease and matched control subjects. Using washed membrane homogenates from the frontal cortex, hippocampus, caudate nucleus, and putamen, saturation analysis of specific receptor binding was performed for the total number of muscarinic receptors with [3H]quinuclidinyl benzilate, for muscarinic M1 receptors with [3H]pirenzepine, for muscarinic M2 receptors with [3H]oxotremorine-M, and for nicotinic receptors with (-)-[3H]nicotine. In comparison with control tissues, choline acetyl-transferase activity was reduced in the frontal cortex and hippocampus and unchanged in the caudate nucleus and putamen of parkinsonian patients. In Parkinson's disease the maximal binding site density for [3H]quinuclidinyl benzilate was increased in the frontal cortex and unaltered in the hippocampus, caudate nucleus, and putamen. Specific [3H]pirenzepine binding was increased in the frontal cortex, unaltered in the hippocampus, and decreased in the caudate nucleus and putamen. In parkinsonian patients Bmax values for specific [3H]oxotremorine-M binding were reduced in the cortex and unchanged in the hippocampus and striatum compared with controls. Maximal (-)-[3H]nicotine binding was reduced in both the cortex and hippocampus and unaltered in both the caudate nucleus and putamen. Alterations of the equilibrium dissociation constant were not observed for any ligand in any of the brain areas examined. The present results suggest that both the innominatocortical and the septohippocampal cholinergic systems degenerate in Parkinson's disease.(ABSTRACT TRUNCATED AT 250 WORDS
Inclusion of unsteady aerodynamics in longitudinal parameter estimation from flight data
A simple vortex system, used to model unsteady aerodynamic effects into the rigid body longitudinal equations of motion of an aircraft, is described. The equations are used in the development of a parameter extraction algorithm. Use of the two parameter-estimation modes, one including and the other omitting unsteady aerodynamic modeling, is discussed as a means of estimating some acceleration derivatives. Computer generated data and flight data, used to demonstrate the use of the parameter-extraction algorithm are studied
Ocean gravity and geoid determination
Gravity anomalies have been recovered in the North Atlantic and the Indian Ocean regions. Comparisons of 63 2 deg x 2 deg mean free air gravity anomalies recovered in the North Atlantic area and 24 5 deg x 5 deg mean free air gravity anomalies in the Indian Ocean area with surface gravimetric measurements have shown agreement to + or - 8 mgals for both solutions. Geoids derived from the altimeter solutions are consistent with altimetric sea surface height data to within the precision of the data, about + or - 2 meters
A study of possible sea state information in the sample and hold gate statistics for the GEOS-3 satellite altimeter
The statistical variations in the sample gate outputs of the GEOS-3 satellite altimeter were studied for possible sea state information. After examination of a large number of statistical characteristics of the altimeter waveforms, it was found that the best sea predictor for H-1/3 in the range of 0 to 3 meters was the 75th percentile of sample and hold gate number 11
Survey of vector-like fermion extensions of the Standard Model and their phenomenological implications
With the renewed interest in vector-like fermion extensions of the Standard
Model, we present here a study of multiple vector-like theories and their
phenomenological implications. Our focus is mostly on minimal flavor conserving
theories that couple the vector-like fermions to the SM gauge fields and mix
only weakly with SM fermions so as to avoid flavor problems. We present
calculations for precision electroweak and vector-like state decays, which are
needed to investigate compatibility with currently known data. We investigate
the impact of vector-like fermions on Higgs boson production and decay,
including loop contributions, in a wide variety of vector-like extensions and
their parameter spaces.Comment: 43 pages, 17 figures; v2: text modified to improve readability,
references added, journal versio
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