33,143 research outputs found
G+++ and Brane Solutions
We demonstrate that the very extended G+++ group element of the form
describes the usual BPS, electric, single brane solutions found in G+++
theories.Comment: One new equation, added references, corrected typos and minor
changes, 42 pages, 6 figures, LaTeX2
Is there a fifth international radiocarbon intercomparison (VIRI)?
The issue of comparability of measurements (and thus bias, accuracy, and precision of measurement) from diverse laboratories is one which has been the focus of some attention both within the radiocarbon community and the wider user communities. As a result, the C-14 community has undertaken a widescale, far-reaching, and evolving program of inter- comparisons, to the benefit of laboratories and users alike. The benefit to the users is, however, indirect, since the C-14 intercomparisons have not been used to generate "league tables" of performance, but rather to allow individual laboratories to check procedures and modify them as required. The historical progression of C-14 laboratory intercomparisons from the Third (TIRI, completed in 1995, Gulliksen and Scott 1995) and Fourth (FIRI, completed in 2000, Scott 2003; Boaretto et al. 2000; Bryant et al. 2002) suggests that a Fifth (VIRI) should also be expected. We describe the plans for VIRI
Low Frequency Gravitational Waves from Black Hole MACHO Binaries
Nakamura, Sasaki, Tanaka, and Thorne have recently estimated the initial
distribution of binary MACHOs in the galactic halo assuming that the MACHOs are
primordial half solar mass black holes, and considered their coalescence as a
possible source for ground-based interferometer gravitational wave detectors
such as LIGO. Evolving their binary distribution forward in time to the
present, the low-frequency (10^{-5} < f < 10^{-1} Hz) spectrum of gravitational
waves associated with such a population of compact binaries is calculated. The
resulting gravitational waves would form a strong stochastic background in
proposed space interferometers such as LISA and OMEGA. Low frequency
gravitational waves are likely to become a key tool for determining the
properties of binaries within the dark MACHO population.Comment: 8 pages + 2 ps figures; AASTe
SENS-5D trajectory and wind-sensitivity calculations for unguided rockets
A computational procedure is described which numerically integrates the equations of motion of an unguided rocket. Three translational and two angular (roll discarded) degrees of freedom are integrated through the final burnout; and then, through impact, only three translational motions are considered. Input to the routine is: initial time, altitude and velocity, vehicle characteristics, and other defined options. Input format has a wide range of flexibility for special calculations. Output is geared mainly to the wind-weighting procedure, and includes summary of trajectory at burnout, apogee and impact, summary of spent-stage trajectories, detailed position and vehicle data, unit-wind effects for head, tail and cross winds, coriolis deflections, range derivative, and the sensitivity curves (the so called F(Z) and DF(Z) curves). The numerical integration procedure is a fourth-order, modified Adams-Bashforth Predictor-Corrector method. This method is supplemented by a fourth-order Runge-Kutta method to start the integration at t=0 and whenever error criteria demand a change in step size
Evolutionary and Physical Properties of Meteoroids
Astrophysical models for meteoroid formation and stellar and planetary evolutions are developed from simulation composition studies
Image-orthicon spectra of Geminids in 1969
The spectra of 25 meteors, recorded with an image orthicon technique in December 1969, are studied in relation to similar records made in August of the same year. Of 19 Geminid meteors in the absolute visual magnitude range 0 to +2, only one showed any evidence of the forbidden line of oxygen at 5577 A, while all Perseid meteors recorded in August exhibited the oxygen line, a result of the large difference in geocentric velocity between the two showers. Atoms identified in faint Geminid meteors include neutral iron, magnesium, calcium and sodium. The molecular bands of nitrogen are also observed
Depletion effects and loop formation in self-avoiding polymers
Langevin dynamics is employed to study the looping kinetics of self-avoiding
polymers both in ideal and crowded solutions. A rich kinetics results from the
competition of two crowding-induced effects: the depletion attraction and the
enhanced viscous friction. For short chains, the enhanced friction slows down
looping, while, for longer chains, the depletion attraction renders it more
frequent and persistent. We discuss the possible relevance of the findings for
chromatin looping in living cells.Comment: 4 pages, 3 figure
Kunsthaus Graz
Kunsthaus Graz (1999–2003), a project for the new museum of modern art in the Austrian city of Graz, designed by Colin Fournier (Partner in Charge) and Peter Cook. Kunsthaus Graz aimed to innovate three areas of architectural design: (1) Creative/provocative engagement with cultural/urban context. (2) Museum design, display techniques and operation: research into the operational philosophy of contemporary museums led to a radical proposal, using new media, flexibility, ephemerality and a less 'institutional' approach to the organization of museum space. (3) New materials, design and manufacturing techniques: the use of a translucent double-curved acrylic surface as the overall envelope required extensive research/experimentation in the use of alternative computer design methods, structural solutions, materials and CAD-CAM manufacturing techniques. Contexts: Kunsthaus Graz moves beyond other contemporary examples of 'biomorphic' architecture, such as Future Systems, Sainsbury Store, Manchester, by exploring the organic surface not only as iconic form but as a new type of 'intelligent' skin capable of displaying information and relating interactively with users. Methods: Kunsthaus Graz develops its research propositions through specifically architectural practice-led processes, namely: (1) A contextual urban approach to ensure the design is perceived as an integral part of the urban fabric, although its form/materiality are in sharp contrast with the surroundings. (2) The search for an innovative, 'organic' form, involving sophisticated geometric analyses in close coordination with structural engineers, evolving towards a 'paperless' design office where the project's concept was manifested via digital 3D data sets, materialized via computer-driven manufacturing processes. (3) A process of continuous testing of new design solutions with respect to the client's programmatic requirements, fire/safety and other regulations, to ensure minimum compromise of the original design concept
Interaction of GABA and Excitatory Amino Acids in the Basolateral Amygdala: Role in Cardiovascular Regulation
Activation of the amygdala in rats produces cardiovascular changes that include increases in heart rate and arterial pressure as well as behavioral changes characteristic of emotional arousal. The objective of the present study was to examine the interaction of GABA and excitatory amino acid (EAA) receptors in the basolateral amygdala (BLA) in regulating cardiovascular function. Microinjection of the GABAA receptor antagonist bicuculline methiodide (BMI) or the E A A receptor agonists NMDA or AMPA into the same region of the BLA of conscious rats produced dose-related increases in heart rate and arterial pressure. Injection of the nonselective EAA receptor antagonist kynurenic acid into the BLA prevented or reversed the cardiovascular changes caused by local injection of BMI or the noncompetitive GABA antagonist picrotoxin. Conversely, local pretreatment with the glutamate reuptake inhibitorl-trans-pyrrolidine-2,4-dicarboxylic acid enhanced the effects of intra-amygdalar injection of BMI. The cardiovascular effects of BMI were also attenuated by injection of either the NMDA antagonist 3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or the AMPA receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide (NBQX). When these two EAA receptor antagonists were combined, their ability to suppress BMI-induced tachycardic and pressor responses was additive. These findings indicate that the cardiovascular effects caused by blockade of GABAergic inhibition in the BLA of the rat are dependent on activation of local NMDA and AMPA receptors
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