2,398 research outputs found
Capabilities and applications of the Program to Optimize Simulated Trajectories (POST). Program summary document
The capabilities and applications of the three-degree-of-freedom (3DOF) version and the six-degree-of-freedom (6DOF) version of the Program to Optimize Simulated Trajectories (POST) are summarized. The document supplements the detailed program manuals by providing additional information that motivates and clarifies basic capabilities, input procedures, applications and computer requirements of these programs. The information will enable prospective users to evaluate the programs, and to determine if they are applicable to their problems. Enough information is given to enable managerial personnel to evaluate the capabilities of the programs and describes the POST structure, formulation, input and output procedures, sample cases, and computer requirements. The report also provides answers to basic questions concerning planet and vehicle modeling, simulation accuracy, optimization capabilities, and general input rules. Several sample cases are presented
Program to Optimize Simulated Trajectories (POST). Volume 1: Formulation manual
A general purpose FORTRAN program for simulating and optimizing point mass trajectories (POST) of aerospace vehicles is described. The equations and the numerical techniques used in the program are documented. Topics discussed include: coordinate systems, planet model, trajectory simulation, auxiliary calculations, and targeting and optimization
Measuring Polynomial Invariants of Multi-Party Quantum States
We present networks for directly estimating the polynomial invariants of
multi-party quantum states under local transformations. The structure of these
networks is closely related to the structure of the invariants themselves and
this lends a physical interpretation to these otherwise abstract mathematical
quantities. Specifically, our networks estimate the invariants under local
unitary (LU) transformations and under stochastic local operations and
classical communication (SLOCC). Our networks can estimate the LU invariants
for multi-party states, where each party can have a Hilbert space of arbitrary
dimension and the SLOCC invariants for multi-qubit states. We analyze the
statistical efficiency of our networks compared to methods based on estimating
the state coefficients and calculating the invariants.Comment: 8 pages, 4 figures, RevTex4, v2 references update
The membrane bound aromatic p-hydroxybenzoic acid oligoprenyltransferase (UbiA) - how iterative improvements lead to a realistic structure that offers new insights into functional aspects of prenyl transferases and terpene synthases
Plasmon Evolution and Charge-Density Wave Suppression in Potassium Intercalated Tantalum Diselenide
We have investigated the influence of potassium intercalation on the
formation of the charge-density wave (CDW) instability in 2H-tantalum
diselenide by means of Electron Energy-Loss Spectroscopy and density functional
theory. Our observations are consistent with a filling of the conduction band
as indicated by a substantial decrease of the plasma frequency in experiment
and theory. In addition, elastic scattering clearly points to a destruction of
the CDW upon intercalation as can be seen by a vanishing of the corresponding
superstructures. This is accompanied by a new superstructure, which can be
attributed to the intercalated potassium. Based on the behavior of the c-axis
upon intercalation we argue in favor of interlayer-sites for the alkali-metal
and that the lattice remains in the 2H-modification
Incidence of anorexia nervosa and the prescribing of psychotropic medications from UK Primary Care, 1996-2016: A retrospective database study
Global existence of classical solutions to the Vlasov-Poisson system in a three dimensional, cosmological setting
The initial value problem for the Vlasov-Poisson system is by now well
understood in the case of an isolated system where, by definition, the
distribution function of the particles as well as the gravitational potential
vanish at spatial infinity. Here we start with homogeneous solutions, which
have a spatially constant, non-zero mass density and which describe the mass
distribution in a Newtonian model of the universe. These homogeneous states can
be constructed explicitly, and we consider deviations from such homogeneous
states, which then satisfy a modified version of the Vlasov-Poisson system. We
prove global existence and uniqueness of classical solutions to the
corresponding initial value problem for initial data which represent spatially
periodic deviations from homogeneous states.Comment: 23 pages, Latex, report #
Optical scalars in spherical spacetimes
Consider a spherically symmetric spacelike slice through a spherically
symmetric spacetime. One can derive a universal bound for the optical scalars
on any such slice. The only requirement is that the matter sources satisfy the
dominant energy condition and that the slice be asymptotically flat and regular
at the origin. This bound can be used to derive new conditions for the
formation of apparent horizons. The bounds hold even when the matter has a
distribution on a shell or blows up at the origin so as to give a conical
singularity
Matrix-free calcium in isolated chromaffin vesicles
Isolated secretory vesicles from bovine adrenal medulla contain 80 nmol of Ca2+ and 25 nmol
of Mg2+ per milligram of protein. As determined with a Ca2+-selective electrode, a further accumulation
of about 160 nmol of Ca2+/mg of protein can be attained upon addition of the Ca2+ ionophore A23187.
During this process protons are released from the vesicles, in exchange for Ca2+ ions, as indicated by the
decrease of the pH in the incubation medium or the release of 9-aminoacridine previously taken up by the
vesicles. Intravesicular Mg2+ is not released from the vesicles by A23 187, as determined by atomic emission
spectroscopy. In the presence of N H Q , which causes the collapse of the secretory vesicle transmembrane
proton gradient (ApH), Ca2+ uptake decreases. Under these conditions A23 187-mediated influx of Ca2+
and efflux of H+ cease at Ca2+ concentrations of about 4 pM. Below this concentration Ca2+ is even released
from the vesicles. At the Ca2+ concentration at which no net flux of ions occurs the intravesicular matrix
free Ca2+ equals the extravesicular free Ca2+. In the absence of NH4C1 we determined an intravesicular
pH of 6.2. Under these conditions the Ca2+ influx ceases around 0.15 pM. From this value and the known
pH across the vesicular membrane an intravesicular matrix free Ca2+ concentration of about 24 pM was
calculated. This is within the same order of magnitude as the concentration of free Ca2+ in the vesicles
determined in the presence of NH4C1. Calculation of the total Ca2+ present in the secretory vesicles gives
an apparent intravesicular Ca2+ concentration of 40 mM, which is a factor of lo4 higher than the free
intravesicular concentration of Ca2+. It can be concluded, therefore, that the concentration gradient of free
Ca2+ across the secretory vesicle membrane in the intact chromaffin cells is probably small, which implies
that less energy is required to accumulate and maintain Ca2+ within the vesicles than was previously
anticipated
Validation of Kalman Filter alignment algorithm with cosmic-ray data using a CMS silicon strip tracker endcap
A Kalman Filter alignment algorithm has been applied to cosmic-ray data. We
discuss the alignment algorithm and an experiment-independent implementation
including outlier rejection and treatment of weakly determined parameters.
Using this implementation, the algorithm has been applied to data recorded with
one CMS silicon tracker endcap. Results are compared to both photogrammetry
measurements and data obtained from a dedicated hardware alignment system, and
good agreement is observed.Comment: 11 pages, 8 figures. CMS NOTE-2010/00
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