Energy Technology Data Exchange (ETDEWEB)

A real-time orbit feedback system has been implemented at the Advanced Photon Source in order to meet the stringent orbit stability requirements. The system reduces global orbit motion below 30Hz by a factor of four to below 5{micro}m rms horizontally and 2{micro}m rms vertically. This paper focuses on dynamic orbit stability and describes the all-digital orbit feedback system that has been implemented at the APS. Implementation of the global orbit feedback system is described and its latest performance is presented. Ultimately, the system will provide local feedback at each x-ray source point using installed photon BPMs to measure x-ray beam position and angle directly. Technical challenges associated with local feedback and with dynamics of the associated corrector magnets are described. The unique diagnostic capabilities provided by the ...

CERN Document Server

We propose the Particle Swarm Optimization (PSO) as an alternative method for locating periodic orbits in a three--dimensional (3D) model of barred galaxies. We develop an appropriate scheme that transforms the problem of finding periodic orbits into the problem of detecting global minimizers of a function, which is defined on the Poincar\\'{e} Surface of Section (PSS) of the Hamiltonian system. By combining the PSO method with deflection techniques, we succeeded in tracing systematically several periodic orbits of the system. The method succeeded in tracing the initial conditions of periodic orbits in cases where Newton iterative techniques had difficulties. In particular, we found families of 2D and 3D periodic orbits associated with the inner 8:1 to 12:1 resonances, between the radial 4:1 and corotation resonances of our 3D Ferrers bar model. The main advantages of the proposed ...

Energy Technology Data Exchange (ETDEWEB)

Recent work has been carried out on development of isotope wear analysis and optical and eddy current technologies to provide bearing wear measurements and real time monitoring of shaft speed, shaft axial displacement and shaft orbit of the Orbit Transfer Vehicle hydrostatic bearing tester. Results show shaft axial displacement can be optically measured (at the same time as shaft orbital motion and speed) to within 0.3 mils by two fiberoptic deflectometers. Evaluation of eddy current probes showed that, in addition to measuring shaft orbital motion, they can be used to measure shaft speed without having to machine grooves on the shaft surface as is the usual practice for turbomachinery. The interim results of this condition monitoring effort are presented.

CERN Document Server

Two quantities play a central role in that part of nonlinear optics which deals with the effects of a finite momentum spread in a particle beam: the orbit position whose derivative with respect to momentum is called 'orbit dispersion' and the betatron wave number whose derivative WRT momentum is the 'chromaticity'. The orbit dispersion varies with the azimuth and is essentially horizontal in a machine with a horizontal symmetry plane; parasitic radial fields induce a vertical component. The chromaticity is a scalar quantity related to the integral of the focusing strength, over one turn of the machine; it is defined for the horizontal and vertical planes. After recalling the general motion equation in the horizontal plane, the orbit dispersion and the chromaticity will be treated. Closed formulae are given for lumped elements and special emphasis is put on dipoles with a high ...

CERN Document Server

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antinuclei with a precision of the order of $10^{-8}$). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, $15^{th}$ 2006 in a $350\\times 600 km$ orbit with an inclination of 70 degrees. In this work we describe the scientific objectives and the performance of PAMELA in its first two years of operation. Data on protons of trapped, secondary and galactic nature - as well as measurements of the December $13^{th}$ 2006 Solar Particle Event - are also provided.

CERN Document Server

The traditional way of estimating the gravitational field from observed motions of test objects is based on the virial relation between their kinetic and potential energy. We find a more efficient method. It is based on the natural presumption that the objects are observed at a random moment of time and therefore have random orbital time phases. The proposed estimator, which we call "orbital roulette", checks the randomness of the phases. The method has the following advantages: (1) It estimates accurately Keplerian (point-mass) potentials as well as non-Keplerian potentials where the unknown gravitating mass is distributed in space. (2) It is a complete statistical estimator: it checks a trial potential and accepts it or rules it out with a certain significance level; the best-fit measurement is thus supplemented with error bars at any confidence level. (3) It needs no a priori assumptions about the distribution of ...

CERN Document Server

We study the stability of the circular orbits of the electromagnetic two-body problem of classical electrodynamics. We introduce the concept of resonant dissipation, i.e. a motion that radiates the center-of-mass energy while the interparticle distance performs bounded oscillations about a metastable orbit. The stability mechanism is established by the existence of a quartic resonant constant generated by the stiff eigenvalues of the linear stability problem. This constant bounds the particles together during the radiative recoil. The condition of resonant dissipation predicts angular momenta for the metastable orbits in reasonable agreement with the Bohr atom. The principal result is that the emission lines agree with the predictions of quantum electrodynamics (QED) with 1 percent average error even up to the $40^{th}$ line. Our angular momenta depend logarithmically on the mass of the heavy body, such ...

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In calculating the strengths of depolarizing resonances it may be convenient to reformulate the equations of spin motion in a coordinate system based on the actual trajectory of the particle, as introduced by Kondratenko, rather than the conventional one based on a reference orbit. It is shown that resonance strengths calculated by the conventional and the revised formalisms are identical. Resonances induced by radiofrequency dipoles or solenoids are also treated; with rf dipoles it is essential to consider not only the direct effect of the dipole but also the contribution from oscillations induced by it.

Energy Technology Data Exchange (ETDEWEB)

This paper describes the effects of motion of beam components (quads, rf cavities and dipoles) on the beam and considers the properties of a compensation system from the perspective of users. The system departs from standard practice in considering active perturbation of the electron beam to verify beam corrections. The effects of local closed orbit perturbations to direct undulator beams at different experimental setups are also considered.

CERN Document Server

We introduce an ad-hoc electrodynamics with advanced and retarded Lienard-Wiechert interactions plus the dissipative Lorentz-Dirac self-interaction force. We study the covariant dynamical system of the electromagnetic two-body problem, i.e., the hydrogen atom. We perform the linear stability analysis of circular orbits for oscillations perpendicular to the orbital plane. In particular we study the normal modes of the linearized dynamics that have an arbitrarily large imaginary eigenvalue. These large eigenvalues are fast frequencies that introduce a fast (stiff) timescale into the dynamics. As an application, we study the phenomenon of resonant dissipation, i.e., a motion where both particles recoil together in a drifting circular orbit (a bound state), while the atom dissipates center-of-mass energy only. This balancing of the stiff dynamics is established by the existence of a quartic resonant ...

British Library Electronic Table of Contents (United Kingdom)

Using the Galaxy as an example, we study the effect of Formula Not Shown force on the rotational curves of gas and plasma in galaxies. Acceptable model for the galactic magnetic field and plausible physical parameters are used to fit the flat rotational curve for gas and plasma based on the observed baryonic (visible) matter distribution and Formula Not Shown force term in the static MHD equation of motion. We also study the effects of varied strength of the magnetic field, its pitch angle and length scale on the rotational curves. We show that Formula Not Shown force does not play an important role on the plasma dynamics in the intermediate range of distances 6?12?kpc from the centre, whilst the effect is sizable for larger r (r?15?kpc), where it is the most crucial.

CERN Document Server

We propose using large Air Cerenkov Telescopes (ACT's) to search for optical, pulsed signals from extra-terrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of solar luminosities at a distance of 100 pc. The field of view for giant ACT's can be on the order of ten square degrees, and they will be able to monitor 10 to 10$^2$ stars simultaneously for nanosecond pulses of about 6th mag or brighter. Using the Earth's diameter as a baseline, orbital motion of the planet could be detected by timing the pulse arrival times.

CERN Document Server

We derive spin-orbit coupling effects on the gravitational field and equations of motion of compact binaries in the 2.5 post-Newtonian approximation to general relativity, one PN order beyond where spin effects first appear. Our method is based on that of Blanchet, Faye, and Ponsot, who use a post-Newtonian metric valid for general (continuous) fluids and represent pointlike compact objects with a delta-function stress-energy tensor, regularizing divergent terms by taking the Hadamard finite part. To obtain post-Newtonian spin effects, we use a different delta-function stress-energy tensor introduced by Bailey and Israel. In a future paper we will use the 2.5PN equations of motion for spinning bodies to derive the gravitational-wave luminosity and phase evolution of binary inspirals, which will be useful in constructing matched filters for signal analysis. The gravitational field derived here may help in posing initial data ...

CERN Document Server

An accident of misidentification has brought to light the interesting system HD 191588, a new RS CVn-type spectroscopic binary. A radial-velocity study of the primary star, the only seen component, carried out at the Observatoire de Haute-Provence with the Coravel instrument and subsequently at the Cambridge Observatories with a similar one, reveals two orbital motions: a short-period orbit (60 days) and a long-period one (about 4.5 years), so this star is a triple system. The following orbital elements are obtained: (1) for the long-period orbit P = 1667+/-17 days, T = 50901 +/-67 MJD, Gamma = +2.09 +/-0.07 km/s, K = 2.51 +/-0.13 km/s, e = 0.18 +/-0.04, omega = 228deg +/- 14 deg, a1 sin i = 56.7 +/- 3.0 Gm, f(m) = 0.0026 +/-0.0004 M_sun, and (2) for the short-period orbit P = 60.0269 +/-0.0016 days, T = 50482.6 +/-3.3 MJD, gamma is var., K = 24.03 +/- 0.09 ...

CERN Document Server

Because Spitzer is an Earth-trailing orbit, losing about 0.1 AU/yr, it is excellently located to perform microlens parallax observations toward the Magellanic Clouds (LMC/SMC) and the Galactic bulge. These yield the so-called ``projected velocity'' of the lens, which can distinguish statistically among different populations. A few such measurements toward the LMC/SMC would reveal the nature of the lenses being detected in this direction (dark halo objects, or ordinary LMC/SMC stars). Cool Spitzer has already made one such measurement of a (rare) bright red-clump source, but warm (presumably less oversubscribed) Spitzer could devote the extra time required to obtain microlens parallaxes for the more common, but fainter, turnoff sources. Warm Spitzer could observe bulge microlenses for 38 days per year, which would permit up to 24 microlens parallaxes per year. This would yield interesting information on the disk mass function, particularly old ...

CERN Document Server

Magnetic fields correlated on several kiloparsec scales are seen in spiral galaxies. Their origin could be due to the winding up of a primordial cosmological field or due to amplification of a small seed field by a turbulent galactic dynamo. Both options have difficulties: There is no known battery mechanism for producing the required primordial field. Equally the turbulent dynamo may self destruct before being able to produce the large scale field, due to excess generation of small scale power. The current status of these difficulties is discussed. The resolution could depend on the nature of the saturated field produced by the small scale dynamo. We argue that the small scale fields do not fill most of the volume of the fluid and instead concentrate into intermittent ropes, with their peak value of order equipartition fields, and radii much smaller than their lengths. In this case these fields neither drain significant energy from the turbulence nor convert eddy ...

Energy Technology Data Exchange (ETDEWEB)

Fluctuations in the flux of runaway electrons to the limiter have been measured during many PLT discharges. Oscillations at 60, 120, and 720 Hz are driven by variations in the vertical magnetic field which moves the plasma major radius. Fluctuations are seen in the range of 2 ..-->.. 20 kHz due to MHD magnetic islands which extend to the plasma surface. A continuous spectrum of fluctuations is observed up to 200 kHz which correlates with drift-wave turbulence. The magnitude of the driven fluctuations can be used to measure transport properties of the runaway electrons. The amplitude of electron motion due to the MHD and drift-wave oscillations, and hence a measure of the radial size of the instability, can be determined as a function of frequency. The slope of the frequency power spectrum of the drift-wave-induced fluctuations steepens with increasing runaway electron drift orbit displacement during the current drop at the end of the ...

Science.gov (United States)

Spontaneous radiation emitted from relativistic electrons undergoing betatron motion in a plasma-focusing channel is analyzed, and applications to plasma wake-field accelerator experiments and to the ion-channel laser (ICL) are discussed. Important similarities and differences between a free electron laser (FEL) and an ICL are delineated. It is shown that the frequency of spontaneous radiation is a strong function of the betatron strength parameter a(beta), which plays a role similar to that of the wiggler strength parameter in a conventional FEL. For a(beta) > or approximately 1, radiation is emitted in numerous harmonics. Furthermore, a(beta) is proportional to the amplitude of the betatron orbit, which varies for every electron in the beam. The radiation spectrum emitted from an electron beam is calculated by averaging the single-electron spectrum over the electron distribution. This leads to a frequency broadening of the radiation ...

CERN Document Server

We report results of the 2006 April multi-wavelengths campaign of SS 433, focusing on X-ray data observed with Suzaku at two orbital phases (in- and out-of- eclipse) and simultaneous optical spectroscopic observations. By analyzing the Fe25 K_alpha lines originating from the jets, we detect rapid variability of the Doppler shifts, dz/dt ~ 0.019/0.33 day^-1, which is larger than those expected from the precession and/or nodding motion. This phenomenon probably corresponding to "jitter" motions observed for the first time in X-rays, for which significant variability both in the jet angle and intrinsic speed is required. From the time lag of optical Doppler curves from those of X-rays, we estimate the distance of the optical jets from the base to be ~(3-4) \\times 10^14 cm. Based on the radiatively cooling jet model, we determine the innermost temperature of the jets to be T_0 = 13 +/- 2 keV and 16 +/- 3 keV (the average of ...

CERN Document Server

The abstract is additional with repect to the paper published in JGCD. Ordinary Earth satellites are usually placed into five categories of special orbits: sun-synchronous orbits, orbits at the critical inclination, frozen orbits, repeating ground track orbits, and geostationary orbits. This paper investigates their counterparts around Mars and examines the basic nature of these orbits, which are of special interest for missions conducted around Mars, including Mars reconnaissance. Mars' gravity field is much more complicated, with relatively smaller J2, compared to Earth's, which makes the behaviors of these Martian orbits different from those of Earth. Analytical formulations and numerical simulations are used to analyze these Martian orbits and compare them with their Earth counterparts. First, ...

Energy Technology Data Exchange (ETDEWEB)

A remarkably simple argument successfully accounts for the rate of star formation in different galaxies. The snag is that the timescale is uncomfortably short.

Science.gov (United States)

is launched from the Baikonur Cosmodrome in Kazakstan. Tomorrow's picture: A Galactic Whirlpool ...

Science.gov (United States)

An orbital emplacement for the transmitter and the antenna of a communications link at ELF (30 to

Energy Technology Data Exchange (ETDEWEB)

An experimental apparatus has been built that allows direct measurement of the oil film thickness in a bearing that is subjected to dynamic loads and shaft speeds representative of those occurring in automotive engine connecting rod, big-end bearings. Dynamic motion of the shaft, relative to the bearing, is measured as a function of shaft rotational angle, using non-contact, eddy-current probes. A computer based data acquisition system is used to measure, record, and analyze the journal position in the bearing. The test bearing is 63.5 mm in diameter by 25.4 mm long, and is loaded using a servo-hydraulic actuator rated at 98.3 kN. The journal has an operating speed of 500 to 3800 rpm. The actuator is controlled by a computer-generated waveform that can duplicate load profiles developed by various engines operating at a wide range of conditions. Measurements taken with the shaft statically loaded show excellent agreement with results calculated using short bearing ...

KoreaScience (Korea)

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J-STORE (Japan)

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Energy Technology Data Exchange (ETDEWEB)

This paper describes a simple analysis procedure that transforms a set of beamline orbit data into a set of harmonic orbits of first, second, and third order or higher. Each harmonic orbit can be studied individually to identify errors of the specific order with minimum interference from other orders. Effectively these are orbits caused by kicks, due to harmonic errors, propagated through linear lattice. Examples from accelerator study will be presented. The application and inherent limitations of this analysis procedure are discussed.

Energy Technology Data Exchange (ETDEWEB)

Recent analyses of the anisotropy of cosmic rays at 10{sup 18} eV (the AGASA and SUGAR data) show significant excesses from regions close to the galactic centre and Cygnus. Our aim is to check whether such anisotropies can be caused by single sources of charged particles. We investigate propagation of protons in two models of the galactic regular magnetic field (with the irregular component included) assuming that the particles are injected by a short-lived discrete source lying in the direction of the galactic centre. We show that apart from a prompt image of the source, the regular magnetic field may cause delayed images at quite large angular distances from the actual source direction. The image is strongly dependent on the time elapsed after ejection of particles and it is also very sensitive to their energy. For the most favourable conditions for particle acceleration by a young pulsar, the predicted fluxes are two to ...

Science.gov (United States)

creating such active galactic nuclei as quasars. Strangely, the center of this fiery whirlpool is offset from the exact center of the galaxy - for a reason that for now remains an...

Science.gov (United States)

circular as possible. (3) GEO (FLTSATCOM, UFO, DSCS, DSP,. Milstar): Boost to an orbit at least 300 km above GEO in an orbit as near circular as possible. ...

International Nuclear Information System (INIS)

Malignant tumors of the sinonasal cavities are rare and often diagnosed late in the course of the disease. These tumors can extend into regions such as the orbit and brain, where treatment is difficult. Ten patients with non treated sinonasal malignant neoplasms and radiological evidence of tumor extension into the orbit and brain were studied with computed tomography. Five (50%) tumors were epithelial neoplasms whereas squamous cell carcinoma was the most common type (3 cases). The ethmoidal sinus was the most common site of origin of the tumors (40%), followed by the maxillary sinus (30%) and nasal cavity (30%). A total of 16 orbits were involved since 6 patients (60%) had bilateral orbital involvement. The tumors extended more often into the orbits through erosion of the medial and inferior orbital bones. All orbital compartments were ...

Energy Technology Data Exchange (ETDEWEB)

The problem on change of deuterium abundance in the process of galactic evolution (star evolution, supernova explosions, nucleosynthesis in supermassive objects) is considered. It is shown that the observable deuterium quantity in the interstellar medium must correspond to its cosmological abundance. This conclusion is independent of the rate of accretion of intergalactic gas by Galaxy. The effect of hypothetical pregalactic active objects on cosmological deuterium is small. It is poind out that observations of interstellar deuterium in absorbtion at lambda=91.6 cm are significant.

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A new era for the field of Galactic structure is about to be opened with the advent of wide-area digital sky surveys. In this article, the author reviews the status and prospects for research for 3 new ground-based surveys: the Sloan Digital Sky Survey (SDSS), the Deep Near-Infrared Survey of the Southern Sky (DENIS) and the Two Micron AU Sky Survey (2MASS). These surveys will permit detailed studies of Galactic structure and stellar populations in the Galaxy with unprecedented detail. Extracting the information, however, will be challenging.

Energy Technology Data Exchange (ETDEWEB)

We describe a global closed orbit feedback experiment, based upon a real time harmonic analysis of both the orbit movement and the correction magnetic fields. The feedback forces the coefficients of a few harmonics near the betatron tune to vanish, and significantly improves the global orbit stability. We present the results of the experiment in the UV ring using 4 detectors and 4 trims, in which maximum observed displacement was reduced by a factor of between 3 and 4. 4 refs., 3 figs.

Energy Technology Data Exchange (ETDEWEB)

We retrospectively studied the computed tomography scans of the orbit in 75 patients in order to identify the presence of incidental calcifications (scleral and trochlear apparatus calcifications.). These imaging findings should integrate the vast list of differential diagnosis of orbital calcifications, as they may help radiologists to distinguish these calcifications from orbital foreign bodies. (author)

UK PubMed Central (United Kingdom)

Cancer treatment with ionizing radiation is often compromised by organ motion, in particular for lung cases. Motion uncertainties can significantly degrade an otherwise optimized treatment plan....Full Text Available

CERN Document Server

The possible physical linkage between galactic cosmic rays intensity and the Earth's cloud cover is discussed using the analysis of the first indirect aerosol effect (Twomey effect) and its experimental representation as the dependence of average cloud droplet effective radius on aerosol index characterizing the aerosol concentration in the atmospheric air column of unit section. It is shown that the basic kinetic equation of the Earth's climate energy-balance model is described by the bifurcation equation (with respect to the temperature of the Earth's surface) in the form of fold catastrophe with two governing parameters defining the variations of insolation and Earth's magnetic field (or galactic cosmic rays intensity in the atmosphere), respectively. The principle of hierarchical climatic models construction, which consists in the structural invariance of balance equations of these models evolving on the different time scales, is described. ...

International Nuclear Information System (INIS)

The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow is a fundamental assumption common to all binary stellar evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the evolution of the orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion onto the companion star within a single orbit, self-accretion back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star, possibly leading to the formation of a disk. We calculate the secular evolution of the binary ...

UK PubMed Central (United Kingdom)

We describe the characteristics of the rapidly rotating molecular disk in the nucleus of the mildly active galaxy NGC4258. The morphology and kinematics of the disk are delineated by the point-like...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Massive particle candidates for dark matter provide a potentially observable signature by virtue of their annihilations in the galactic halo at a known but model-dependent rate. Possible signatures are described, including cosmic ray antiproton and gamma-ray production. (orig.).

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The motion of a test particle moving in an interior static spherically symmetric geometry is investigated. The author concludes that an oscillatory motion with the test particle changing its motion from a free fall towards the center to an outward radial motion can not exist for any static interior spherically symmetric model.

KoreaScience (Korea)

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International Nuclear Information System (INIS)

The authors have investigated here whether tachyons can move in stable circular orbits in Kerr, Kerr-Newmann and Lewis fields owing to their dragging effect. It is found that stable circular orbits are possible only in a Lewis field. (author).

Energy Technology Data Exchange (ETDEWEB)

We have investigated the effect of the rho tensor coupling on binding energies, matter root-mean-square radii and spin orbit splittings of Ca isotopes in the relativistic mean-field theory with sigma, omega, and rho mesons. It is shown that binding energies and matter root-mean-square radii are insensitive to an alteration in the strength of the rho tensor coupling and an explanation of this is given. We have further shown that inclusion of the rho tensor coupling will give isospin-dependent spin-orbit splittings and this will greatly affect spin-orbit splittings of nuclei near the neutron drip line. (author). Letter-to-the-editor.

Science.gov (United States)

Subcritical cryogenic fluid management has long been recognized as an enabling technology for key

Science.gov (United States)

... the cinder-like planets in orbit around pulsars, the remnants of massive star evolution) to worlds that are more reassuringly familiar. ...

Energy Technology Data Exchange (ETDEWEB)

The authors present an unusual case of a patient with orbital metastases from renal carcinoma involving the extra ocular muscles bilaterally. The importance of computed tomography for the differential diagnosis with other orbital lesions is emphasized. (author)

Energy Technology Data Exchange (ETDEWEB)

The effect of weak dissipation on drift orbits has been investigated making use of a simple mapping model in a helical magnetic field. It is found that, after many mapping iterations, any orbit tends to an attractor forming a vortex line even with very small dissipation. The convergence is faster for larger dissipation, i.e., the number of iteration N to converge within a certain distance from the attractor is inversely proportional to the amount of the dissipation. Although the behavior of orbits completely change, the basic stability characteristics of the system does not change, i.e, the coordinate of the attractors are determined by the stable fixed points in the area preserving system because the dissipation is very small. Since wide range of orbits are concentrated around the attractors after many toroidal circulations, a pinch effect is created by a small dissipation. Application of this pinch ...

Energy Technology Data Exchange (ETDEWEB)

The synchronous orbit performance of Hughes Aircraft Company solar arrays is presented and compared with the results of ground based predictions for orbital durations of almost 11 years. Performances of the Intelsat IV*, IVA*, and Telesat (Anik) solar arrays are detailed. This paper is an update of the in-orbit performances previously reported in 1976 (1). The in-space performance data indicate solar array power degradation of 16.7 percent for Intelsat IV F-2 after 130 months in orbit, and 13.0 percent for Telesat F-1 after 85 months in orbit. The predicted output of each of these solar arrays is within 2 percent of the actual in-orbit performance of these systems. The Intelsat IV F-2 experienced the 4 August 1972 solar flare. The ability to accurately predict the performance of solar arrays within telemetry accuracy is demonstrated. This ability combines the ...

UK PubMed Central (United Kingdom)

ObjectiveTo evaluate a faith-based intervention (“Sisters in Motion”) intended to increase walking among older, sedentary African American women.Full Text Available

UK PubMed Central (United Kingdom)

BackgroundTo better understand the underlying mechanisms involved in trunk motion during a tennis serve, this study aimed to examine the (1) relative motion of the middle and lower...Full Text Available

Science.gov (United States)

... The relatively large, low frequency multi-axis motions observed at the chest may be a contributor to discomfort in locomotive engineers. ...

Energy Technology Data Exchange (ETDEWEB)

The present paper is concerned with the prediction method for the motions and tensions of mooring lines on slack-moored floating oceanic architectural building in coastal zone. The motions and the tensions of mooring lines were estimated by the time domain numerical simulation in the present method. The present method includes the nonlinearity of mooring system, slow varying wave drift force. The authors performed a time domain numerical simulation for motions and the tensions of mooring lines on floating barge in two component waves. Also, the results obtained by numerical simulation were compared with the experimental results. The validity of the present method was confirmed.

Energy Technology Data Exchange (ETDEWEB)

Generalized dynamic motion of balls and cage in a ball bearing are simulated by solving the differential equations of motion under prescribed operating conditions and bearing geometry. The general cage motion is parametrically evaluated as a function of clearances both in the ball pockets and at the guide lands. The design significance of the modeling approach is demonstrated by the prediction of critical clearances which trigger certain instabilities in the cage motion. In more practical terms, the correlation between cage clearances and instability defines a wear life for the bearing under the prescribed operating conditions. 10 refs.

Science.gov (United States)

runs are necessary, provision shall be made for expansion joints, motion of the units, or similar compensation to ensure that no excessive strains are ...

CERN Document Server

The Jacobi and Weierstrass elliptic functions used to be part of the standard mathematical arsenal of physics students. They appear as solutions of many important problems in classical mechanics: the motion of a planar pendulum (Jacobi), the motion of a force-free asymmetric top (Jacobi), the motion of a spherical pendulum (Weierstrass), and the motion of a heavy symmetric top with one fixed point (Weierstrass). The problem of the planar pendulum, in fact, can be used to construct the general connection between the Jacobi and Weierstrass elliptic functions. The easy access to mathematical software by physics students suggests that they might reappear as useful tools in the undergraduate curriculum.

CERN Document Server

Satellite CMB anisotropy missions and new generation of balloon-borne and ground experiments, make use of complex multi-frequency instruments at the focus of a meter class telescope. Between 70 GHz and 300 GHz, where foreground contamination is minimum, it is extremely important to reach the best trade-off between the improvement of the angular resolution and the minimization of the straylight contamination mainly due to the Galactic emission. We focus here, as a working case, on the 30 and 100 GHz channels of the Planck Low Frequency Instrument (LFI). We evaluate the GSC introduced by the most relevant Galactic foreground components for a reference set of optical configurations. We show that it is possible to improve the angular resolution of 5-7% by keeping the overall GSC below the level of few microKelvin. A comparison between the level of straylight introduced by the different Galactic components for different beam ...

CERN Document Server

For purposes of designing targeted cataclysmic variable (CV) detection surveys and interpreting results of other projects with many CV detections such as the ChaMPlane Survey, we have created a model of the CV distribution in the Galaxy. It is modeled as a warped, flared exponential disk with a gaussian vertical distribution. Extinction is based on a detailed Galactic dust and gas model. A luminosity function for CVs is also incorporated, based on a smoothed version of published data. We calculate predicted field detection rates as a function of the limiting magnitude expected for the detecting system (i.e. WIYN/Hydra or NOAO 4m/Mosaic). Monte-Carlo techniques are used to assess statistical fluctuations in these rates. We have created maps of the expected CV distribution for the full non-bulge Galactic plane (20

Science.gov (United States)

We study a kinetic model for a system of two species of particles interacting via a repulsive long range potential and with a reservoir at fixed temperature. The interaction between the particles is modeled by a Vlasov term and the thermal bath by a Fokker-Planck term. We show that in the diffusive and sharp interface limit the motion of the interfaces at low temperature is described by a Stefan problem or a Mullins-Sekerka motion, depending on the time scale.

Energy Technology Data Exchange (ETDEWEB)

The paper deals with a model in which the motion of a gas in plasma accerators and high-curent discharges in the present of a skin effect is treated as expulsion by a 'magnetic piston' under the action of surface current flow. Specifically examined is the situation where the initial gas pressure is negligible in comparison with the magnetic pressure, and the motion of the gas may be treated as a self-simulating one. A system of hydrodynamic equations of the problem is derived and integrated by Adam's method. Results are plotted and discussed.

Science.gov (United States)

The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and ...

CERN Document Server

We present evidence in favour of a link between the luminosity radiatively dissipated in the central engine of radio-loud Active Galactic Nuclei and the kinetic power in their jets. This piece of evidence is based on the relation we find between the luminosity in broad emission lines and the kinetic power in pc-scale radio jets, for a sample of radio-loud quasars for which suitable data are available in the literature. We find that the ionizing luminosity and the kinetic one are of the same order of magnitude, suggesting that the processes responsible for them are somehow related. A strong magnetic field in equipartition with the radiation field could be responsible for regulating both processes. BL Lac objects seem to follow a similar behaviour, but with comparatively fainter broad line emission.

Energy Technology Data Exchange (ETDEWEB)

We treat symmetric semi-infinite nuclear matter in the relativistic mean-field approximation for the scalar-vector field theoretical model. Using special-type Dirac spinors the nucleonic Dirac equation is decoupled into two sets of differential equations for the spin-orientation dependent orbital nucleon Dirac spinors. We also rewrite the Dirac equation in terms of second-order differential equations with the spin-orbit interaction appearing explicitly. These equations can be solved if the spin-orbit part is left out. The spin-orbit effects thus can be isolated, and are shown to reduce the surface energy coefficient a/sub s/ as well as the surface thickness t in such a way that their ratio remains practically unchanged. For realistic lagrangians - in linear as well as non-linear forms - consistent with the empirical spin-orbit single-partial level splittings, a/sub s/ is reduced by ...

International Nuclear Information System (INIS)

Decay sequences based on the 1/2"+[660] proton orbital have been identified in "1"7"1Ta and "1"7"7Re based on spin, parity, and large alignment. This decay sequence is observed higher in energy than predicted in cranking calculations based on modified oscillator potentials. Similarly known 1/2"-[541] decay sequences in these and other neighbouring isotopes are observed lower in energy than predicted. A reduction in the strength of the spin-orbit potential for protons is suggested as a solution to these problem. (orig.).

Energy Technology Data Exchange (ETDEWEB)

This book presents the basic ideas of the physics of non-gravitational perturbations and the mathematics required to compute their orbital effects. It conveys the relevance of the different problems that must be solved to achieve a given level of accuracy in orbit determination and in recovery of geophysically significant parameters. Selected Contents are: Orders of Magnitude of the Perturbing Forces, Tides and Apparent Forces, Tools from Celestial Mechanics, Solar Radiation Pressure-Direct Effects: Satellite-Solar Radiation Interaction, Long-Term Effects on Semi-Major Axis, Radiation Pressure-Indirect Effects: Earth-Reflected Radiation Pressure, Anisotropic Thermal Emission, Drag: Orbital Perturbations by a Drag-Like Force, and Charged Particle Drag.

International Nuclear Information System (INIS)

A study of the #pi#1g/sub 9/2/ orbit size in "8"8Sr, "9"0Zr, and "9"2Mo is presented. The rms radius for the point-proton density is extracted by studying transitions to 8"+ states in these nuclei. The radii are consistently larger than a value determined in a magnetic electron scattering experiment on "9"3Nb. A qualitative discussion of the ground state occupation of the #pi#1g/sub 9/2/ orbit based on the transition amplitudes to the 8"+ states is given.

International Nuclear Information System (INIS)

This paper reviews generation methods of artificial earthquake motion and proposes an improved method of generating input motions for use in vibration tests of equipment to prove aseismic performance. The improved method employs beat wave repetition characteristic that inherently appears in the component waves of recorded earthquakes decomposed by bandpass filter and algebraic function phase for the component waves. Typical motions generated by the improved method satisfies prescribed severe conditions such as target response spectrum that are defined with a wideband frequency component and a limited maximum acceleration due to shaking table performance. The motions had never been generated by the conventional method.

Science.gov (United States)

Oct 2, 2007 ... Other payloads included the Orbiter Experiments Autonomous Supporting Instrumentation System-1 (OASIS-1), a cooling system designed for ...

Science.gov (United States)

Apr 22, 2010 ... I believe that space exploration is not a ... plan for space exploration, especially in .... space exploration beyond low Earth orbit. ...

Science.gov (United States)

Sep 21, 2007... at night," said Glen Cushing of the U.S. Geological Survey's Astrogeology Team and of Northern Arizona University, Flagstaff, Ariz. ...

CERN Document Server

We investigate the equivariant cohomology of the natural torus action on a K-contact manifold and its relation to the topology of the Reeb flow. Using the contact moment map, we show that the equivariant cohomology of this action is Cohen-Macaulay, which is a generalization of equivariant formality for torus actions without fixed points. As a consequence, a generic component of the contact moment map is a perfect Morse-Bott function for the basic cohomology of the orbit foliation F of the Reeb flow. Assuming that the closed Reeb orbits are isolated, we show that the basic cohomology of F is trivial in odd degrees, and its dimension equals the number of closed Reeb orbits. We characterize the K-contact manifolds with minimal number of closed Reeb orbits as real cohomology spheres. We also prove a GKM type theorem for K-contact manifolds, which allows us to calculate the equivariant cohomology algebra of ...

International Nuclear Information System (INIS)

Surface photometry of bulges and elliptical galaxies is reviewed. The properties of cores and nuclei as revealed by improvements in seeing and the use of CCDs are examined, and newly discovered structural details such as dust, shells, and dynamical subsystems which show the importance of accretion events in galactic evolution are addressed. Improved constraints on galaxy formation resulting from better measurements of parameter scaling laws are discussed, and accurate measurements of departures from elliptical isophotes and of color gradients obtained with CCDs are considered.

CERN Document Server

The indirect detection of particle dark matter (DM) is based on the search for anomalous components in cosmic rays (CRs) due to the annihilation of DM pairs in the galactic halo, on the top of the standard astrophysical production. These additional exotic components are potentially detectable at Earth as spectral distortions for the various cosmic radiations: $\\chi + \\chi \\to q \\bar{q}, W^+ W^-, ... \\to \\bar{p}, \\bar{D}, e^+ \\gamma and \

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The contribution of pulsar accelerated nuclei to the cosmic rays inside the Galaxy is calculated assuming that a significant part of the pulsar rotational energy is lost on acceleration of iron nuclei extracted from the surface of the neutron star. Different models of the galactic pulsar population are discussed. It is shown that the best description of the observed cosmic ray spectrum and the mass composition between a few 10{sup 15} eV and a few 10{sup 18} eV is obtained for the model B of Lorimer et al. (1993)

International Nuclear Information System (INIS)

Based on proposed models for the tidal spin-up and magnetic braking of stars with a convective outer envelope, it is suggested that the rotation of secondaries in cataclysmic variables is not necessarily synchronized with the orbital revolution. This may provide an explanation for the observed large range in the mass transfer rate (at the same orbital period) of cataclysmic variables above the period gap. (author).

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Presently available relativistic and nonrelativistic effective interactions do not predict the same behavior for the isotope shifts in the Pb region.We analyze this difference and find that it is related to the characteristics of the spin-orbit term used in the parametrizations. We show that a simple modification of the spin-orbit contribution to the nonrelativistic Skyrme functional solves this problem. ((orig.))

CERN Document Server

We investigate the influence of lunar-like satellites on the infrared orbital light curves of Earth-analog extra-solar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet. We use an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of the Earth while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g. via spectroscopy or ...

CERN Document Server

The vertical profiles of disc galaxies are built by the material trapped around stable periodic orbits, which form their "skeletons". According to this, the knowledge of the stability of the main families of periodic orbits in appropriate 3D models, can predict possible morphologies for edge-on disc galaxies. In a pilot survey we compare the orbital structures which lead to the appearance of "peanuts" and "X"-like features with the edge-on profiles of three disc galaxies (IC 2531, NGC 4013 and UGC 2048). The subtraction from the images of a model representing the axisymmetric component of the galaxies reveals the contribution of the non-axisymmetric terms. We find a direct correspondence between the orbital profiles of 3D bars in models and the observed main morphological features of the residuals. We also apply a simple unsharp masking technique in order to study the sharpest features of the images. ...

International Nuclear Information System (INIS)

An electric propulsion concept suitable for delivering heavy payloads from low earth orbit (LEO) to high energy earth orbit is proposed. The system consists of a number of pulsed inductive plasma thrusters powered by a 100 kWe space nuclear power system. The pulsed plasma thruster is a relatively simple electrodeless device. It also exhibits adequate conversion to thrust power in the desired I sub sp regime of 1500 to 3000 seconds for optimal payload transfer from low earth to high earth orbit. Because of these features and the fact that the nuclear power unit will be capable of delivering sustained high power levels throughout the duration of any given mission, the system presented appears to be a very promising propulsion candidate for advanced orbital transfer vehicle (OTV) applications. An OTV, which makes use of this propulsion system and which has been designed to lift a 9000-lb payload into ...

International Nuclear Information System (INIS)

1984. p. I37. Germany Antonov, AN Christov, CV Petkov, IZ Bylgarska

UK PubMed Central (United Kingdom)

Sensory systems must form stable representations of the external environment in the presence of self-induced variations in sensory signals. It is also possible that the variations themselves may provide...Full Text Available

UK PubMed Central (United Kingdom)

The purpose of this study is to explain the unplanned longitudinal dose modulations that appear in helical tomotherapy (HT) dose distributions in the presence of irregular patient breathing....Full Text Available

UK PubMed Central (United Kingdom)

BackgroundMovement regularities are inherently present in automated goal-directed motions of the primate's arm system. They can provide important signatures of intentional behaviours...Full Text Available

Science.gov (United States)

results of motion energy spectral density measurements in the upper atmosphere for the time interval of 5 minutes to 12 hours, in ...

Science.gov (United States)

... Zinn, J., Hoerlin, H., and Petschek, AG, "The Motion of Bomb Debris Follow- ing the Starfish Test," Radiation Trapped in the Earth's Magnetic Field ...

UK PubMed Central (United Kingdom)

PurposeTo determine the dosimetric impact of inter-fraction anatomical movements in prostate cancer patients receiving proton therapy.Full Text Available

Science.gov (United States)

... 29 *The Motion of Bomb Debris Foflowi'g 'be Starfish Test," J. Zinn, H. Hoerlin, and AG Petschek, BM McCormac, ibid., p. 671-692. ...

Energy Technology Data Exchange (ETDEWEB)

In this paper, a complete solution of the steady-state Newton-Euler equations describing the motion of the balls in high speed thrust bill bearings is presented. Kinematic equations are derived and used as ancillary equations to obtain the numerical solution of the Newton-Euler equations. This differs from previously reported work where extraneous assumptions (instead of kinematic analysis) are used to allow solutions of these equations. It is shown that the no-slip condition for the ball motion reported in the literature is based on an unnecessary assumption. The correct form of the condition is developed and used in the analysis of the ball motion. The analysis shows the importance of contact angle on both ball motion and contact force. An approximate theory is then developed for determining the optimum contact angle that would result in minimum contact force in high speed ball bearings. The results ...

International Nuclear Information System (INIS)

Current methods to calculate dose distributions with organ motion can be broadly classified as 'dose convolution' and 'fluence convolution' methods. In the former, a static dose distribution is convolved with the probability distribution function (PDF) that characterizes the motion. However, artifacts are produced near the surface and around inhomogeneities because the method assumes shift invariance. Fluence convolution avoids these artifacts by convolving the PDF with the incident fluence instead of the patient dose. In this paper we present an alternative method that improves the accuracy, generality as well as the speed of dose calculation with organ motion. The algorithm starts by sampling an isocenter point from a parametrically defined space curve corresponding to the patient-specific motion trajectory. Then a photon is sampled in the linac head and propagated through the three-dimensional (3-D) ...

Science.gov (United States)

Raytheon's Santa Barbara Remote Sensing (SBRS) division designed and built the MTSAT-1R Japanese Advanced Meteorological Imager for the Japanese Ministry of Transport between March, 1999 and July, 2002. In order to meet the stressing requirements of a geosynchronous orbit, a combination of structural, thermal, and optical (STOP) analyses were used to design and optimize the beryllium three-mirror anastigmat (TMA) telescope. This modeling approach was used to characterize and minimize the thermal distortion around local midnight. On-orbit temperatures and structural deformations were predicted using thermal Desktop/SINDA and PATRAN/NASTRAN software, respectively. The resulting optical performance was evaluated using Raytheon developed HEXAGON software. The telescope design was successfully optimized to attain specified visible channel performance for most of the 24 hour orbit.

Energy Technology Data Exchange (ETDEWEB)

A study of the ..pi..1g/sub 9/2/ orbit size in /sup 88/Sr, /sup 90/Zr, and /sup 92/Mo is presented. The rms radius for the point-proton density is extracted by studying transitions to 8/sup +/ states in these nuclei. The radii are consistently larger than a value determined in a magnetic electron scattering experiment on /sup 93/Nb. A qualitative discussion of the ground state occupation of the ..pi..1g/sub 9/2/ orbit based on the transition amplitudes to the 8/sup +/ states is given.

CERN Document Server

During searches for new optical Galactic supernova remnants (SNRs) in the high resolution, high sensitivity Anglo-Australian Observatory/United Kingdom Schmidt Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane, we uncovered a variety of filamentary and more diffuse, extensive nebular structures in the vicinity of Wolf-Rayet (WR) star 48 (Theta Muscae), only some of which were previously recognised. We used the double-beam spectrograph of the Mount Stromlo and Siding Spring Observatory (MSSSO) 2.3-m to obtain low and mid resolution spectra of selected new filaments and structures in this region. Despite spectral similarities between the optical spectra of WR star shells and SNRs, a careful assessment of the new spectral and morphological evidence from our deep HAlpha imagery suggests that the putative shell of Theta Mus is not a WR shell at all, as has been commonly accepted, but is rather part of a more complex area of ...

CERN Document Server

We study the sensitivity to neutrino masses of a Galactic supernova neutrino signal as could be measured with the detectors presently in operation and with future large volume water \\v{C}erencov and scintillator detectors. The analysis uses the full statistics of neutrino events. The method proposed uses the principles of Bayesian inference reasoning and has shown a remarkably independence of astrophysical assumptions. We show that, after accounting for the uncertainties in the detailed astrophysical description of the neutrino signal and taking into account the effects of neutrino oscillations in the supernova mantle, detectors presently in operation can have enough sensitivity to reveal a neutrino mass (or to set upper limits) at the level of 1 eV. This is sensibly better than present results from tritium $\\beta$-decay experiments, competitive with the most conservative limits from neutrinoless double $\\beta$-decay and less precise but remarkably less ...

International Nuclear Information System (INIS)

Magnetically driven non-stationary acceleration of jets in active galactic nuclei results in the leading parts of the flow being accelerated to much higher Lorentz factors than in the case of steady-state acceleration with the same parameters. The higher Doppler-boosted parts of the flow may dominate the high-energy emission of blazar jets. We suggest that highly variable GeV and TeV emission in blazars is produced by the faster moving leading edges of highly magnetized non-stationary ejection blobs, while the radio data trace the slower-moving bulk flow. Thus, the radio and gamma-ray emission regions have different, but correlated, Doppler factors. High-energy emission is generated, typically within the optically thick core, in the outer parts of the broad-line emission region, avoiding the radiative drag on the faster parts of the flow. The radio emission should correlate with the gamma-ray emission, delayed with frequency-dependent time lag of the order of weeks ...

CERN Document Server

Gemini North adaptive optics imaging spectroscopy is presented for the Galactic ultra-compact HII (UCHII) region K3-50A. Data were obtained in the K-band using the Near-infrared Integral Field Spectrograph (NIFS) behind the facility adaptive optics module ALTAIR in natural guide star mode. The NIFS data cube reveals a complex spatial morphology across the 0.1 pc scale of the 3'' UCHII region. Comparison of the nebular emission to Cloudy ionization models shows that the central source must have an effective temperature between about 37000 K and 45000 K with preferred values near 40000 K. Evidence is presented for sharp density variations in the nebula which are interpreted as a clearing of material nearest the central source. High excitation lines of FeIII and SeIV show that the ionization of the nebula clearly changes with distance from the central source. A double lobed kinematic signature (+/- 25 kms) is evident in the Br gamma line map which may be related to ...

CERN Document Server

In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse $\\gamma$ rays when taking the source distribution compatible with supernova remnants data, which ...

CERN Document Server

Recent X-ray and radio observations have identified a transient low-mass X-ray binary (LMXB) located only 0.1 pc in projection from the Galactic center, CXOGC J174540.0-290031. In this paper, we report the detailed analysis of X-ray and infrared observations of the transient and its surroundings. Chandra bservations detect the source at a flux of F_X = 2e-12 erg cm^-2 s^-1 (2-8 keV). After accounting for absorption both in the interstellar medium and in material local to the source, the implied luminosity of the source is only L_X = 4e34 erg/s (2-8 keV; D=8 kpc). However, the diffuse X-ray emission near the source also brightened by a factor of 2. The enhanced diffuse X-ray emission lies on top of a known ridge of dust and ionized gas that is visible infrared images. We interpret the X-ray emission as scattered flux from the outburst, and determine that the peak luminosity of CXOGC J174540.0-290031 was >2e36 erg/s. We suggest that the relatively small observed ...

International Nuclear Information System (INIS)

The nuclear power plants with WWER type reactors are characterized by horizontally situated steam generators (SG). During seismic event the horizontal and vertical ground accelerations induce fluid motion in directions of longitudinal and transversal axis. Resulting dynamic forces act on the SG attachment and could cause the failure of screws. In obvious PSA scenarios, these phenomena are classified as a indirect induced LOCA. In this paper the effects of transversal sloshing of fluid are analyzed.

International Nuclear Information System (INIS)

Random motion of a particle, emitting and absorbing tachyons, is investigated. It is shown that if bradyon is in equilibrium with neutral gas, i.e. it absorbs and emits tachyons, which do not have any charges, tha particle with each absorption-emittance of a tachyon changes its energy and momentum, never varying its own mass, and as a result it moves like a brownian particle. Thus, bradyon, interacting with tachyon gas, increases its momentum continuously in agreement with the Einstein-Fokker-Planck type equation.

Science.gov (United States)

Analytical techniques for analyzing the effects of ship motion and attitude on the primary coolant system flow rates are presented. Design data for minimizing these effects are given. (C.J.G.)

British Library Electronic Table of Contents (United Kingdom)

In this article, equations of motion of a manipulator are derived after consideration of the characteristics of the driving source. By considering a collision between a link and an object, and considering the active motion to absorb the kinetic energy of the object, the trajectories for saving energy are calculated by the iterative dynamic programming (IDP) method. The dynamic characteristics of manipulator control based on the trajectory for saving energy are also analyzed theoretically and investigated experimentally.

CERN Document Server

We discuss the advantages which the next generation interferometer SKA (the Square Kilometer Array) will bring for Very Long Baseline Interferometry (VLBI) at centimeter wavelengths. With a sensitivity to micro-Jy level flux density, a brightness temperature limit of about 10.000 K, and an expected dynamic range in future VLBI maps of better than 1.000.000, the impact of SKA on the research of compact extragalactic radio sources and their energetic jets will be very strong. We discuss some consequences, including a possible combination of SKA with future space VLBI missions.

Energy Technology Data Exchange (ETDEWEB)

Hyogo-ken Nanbu earthquake with a focus in the Akashi straits has given huge earthquake damages in and around Awaji Island and Kobe City in 1995. It is clear that the basement structure, which is steeply deepened at Kobe City from Rokko Mountains towards the coast, and the focus under this related closely to the local generation of strong ground motion. Generation process of the strong ground motion was discussed using 2D and 3D numerical simulation methods. The 3D pseudospectral method was used for the calculation. Space of 51.2km{times}25.6km{times}25.6km was selected for the calculation. This space was discretized with the lattice interval of 200m. Consequently, it was found that the basement structure with a steeply deepened basement, soft and weak geological structure thickly deposited on the basement, and earthquake faults running under the boundary of base rock and sediments related greatly to the generation of strong ground ...

International Nuclear Information System (INIS)

The purpose of this investigation is to show that resource to anisotropic compression along a magnetic field is not a necessary condition for star formation within large collapsing interstellar gas clouds. Although such a scenario would certainly eliminate the magnetic field and angular momentum problems associated with isotropically collapsing clouds, it is believed there is sufficient observational theoretical evidence to warrant the present study of magnetically braked, isotropically collapsing gas clouds. It is not attempted to disprove the hypothesis of anisotropic compression, but to offer instead, a reasonable alternative. Angular momentum transfer from magnetically braked, cool interstellar gas clouds of 10"2, 10"3 and 10"4 times the mass of the sun is examined. Magnetic torques acting on a contracting, rotating cloud, permeated by a frozen-in magnetic field coupling the cloud to the galactic field of the surrounding interstellar medium, produce kinks in ...

Energy Technology Data Exchange (ETDEWEB)

This book examines some of the basic principles behind chemical reaction kinetics. Topics considered include the classical trajectory approach to reactive scattering; periodic orbits and theory of reactive scattering; and semiclassical reactive scattering.

Science.gov (United States)

Oct 2, 2007 ... The Payload combines some of the most sensitive particle sensors .... provide state-of-the-art measurements of incoming x-ray, ultraviolet, .... It will be launched into a low-Earth orbit on a Delta 7320 rocket in September 2004. ...

Energy Technology Data Exchange (ETDEWEB)

A statistical treatment has been applied to interpret the experimental data on the Xe M-shell vacancy production in slow 1.05 MeV Xe-Xe collisions and is shown to give better agreement with experiment than that of the molecular-orbital models.

Science.gov (United States)

May 1, 2011 ... Onboard Systems Record Unique Videos of Space Missions ... Corporation, An artist's rendering of LCROSS launching toward the Moon .... Station (ISS) as part of the Commercial Orbital Transportation Services program. ...

Science.gov (United States)

... Figure 3 shows on-orbit (ie, vacuum) frequency aging rates for Milstar rubidium (Rb) clocks, GPS Block IIR Rb clocks, and GPS Block IIA Rb clocks. ...

UK PubMed Central (United Kingdom)

Plutonium possesses the most complicated phase diagram in the periodic table, driven by the complexities of overlapping 5f electron orbitals. Despite the importance of the 5f...Full Text Available

International Nuclear Information System (INIS)

The paper reports on the results of hydrodynamical simulations of the late phase of the common envelope stage of a binary consisting of a 2-solar mass red giant and a 1-solar mass main-sequence companion. The numerical results demonstrate that sufficient energy is released from the orbit to eject the mass within the common envelope without requiring the main-sequence companion to spiral into the white dwarf core of the red giant star. At the end of the simulation the orbital decay time scale increases rapidly to more than 160 yr. The long decay time scale reflects the removal of mass from the common envelope and its subsequent spin-up to near corotation. The ratio of the orbital decay time scale to the mass-loss time scale from the common envelope increases to more than 700, and the mass contained within the common envelope decreases to about 0.01 solar mass or less. It is argued that further orbital ...

International Nuclear Information System (INIS)

We have studied the application of direct aperture optimization (DAO) as an inverse planning tool for breast IMRT. Additionally, we have analysed the impact of respiratory motion on the quality of the delivered dose distribution. From this analysis, we have developed guidelines for balancing the desire for a high-quality optimized plan with the need to create a plan that will not degrade significantly in the presence of respiratory motion. For a DAO optimized breast IMRT plan, the tangential fields incorporate a flash field to cover the range of respiratory motion. The inverse planning algorithm then optimizes the shapes and weights of additional segments that are delivered in combination with the open fields. IMRT plans were generated using DAO with the relative weights of the open segments varied from 0% to 95%. To assess the impact of breathing motion, the dose distribution for the optimized IMRT ...

International Nuclear Information System (INIS)

The technology of nuclear direct propulsion orbit transfer systems based on the Particle Bed Reactor (PBR) is described. A 200 megawatt illustrative design is presented for LEO to GEO and other high #DELTA#V missions. The PBR-NOTV can be used in a one-way mode with the shuttle or an expendable launch vehicle, e.g., the Titan 34D7, or as a two-way reusable space tug. In the one-way mode, payload capacity is almost three times greater than that of chemical OTV's. PBR technology status is described and development needs outlined.

Science.gov (United States)

The electronic transitions and photodissociation of the bromine molecule were studied in the visible-near UV continuum using dynamic simulation. The molar extinction coefficients in this study were obtained in numerical calculations. The quantum yields of the spin-orbit Br*(2 P 1/2) product at different photon frequencies were determined. Time-dependent density functional theory was used to analyze the highest five occupied and lowest five unoccupied Br2 orbitals. The transition to the 1? u state was found to be most probable in the visible-near UV absorption range.

CERN Document Server

Let $\\A$ be an irreducible Coxeter arrangement and $\\bfk$ be a multiplicity of $\\A$. We study the derivation module $D(\\A, \\bfk)$. Any two-dimensional irreducible Coxeter arrangement with even number of lines is decomposed into two orbits under the action of the Coxeter group. In this paper, we will {explicitly} construct a basis for $D(\\A, \\bfk)$ assuming $\\bfk$ is constant on each orbit. Consequently we will determine the exponents of $(\\A, \\bfk)$ under this assumption. For this purpose we develop a theory of universal derivations and introduce a map to deal with our exceptional cases.

Energy Technology Data Exchange (ETDEWEB)

Very often in many textbooks the formalism of the general theory of relativity is applied to gravitational problems. We think that it would be didactically useful to show how it can be adopted also for describing physical situations in accelerated frames of reference by working out in detail a particular case. This choice will also offer an opportunity to discuss a classical topic of relativistic physics. Indeed, we deal analytically with a version of the so-called clock paradox in which the moving clock performs a circular motion. The rest clock is denoted as (1), the rotating clock is (2), the inertial frame in which (1) is at rest and (2) moves is I and, finally, the accelerated frame in which (2) is at rest and (1) rotates is A. By using the general theory of relativity in order to describe the motion of (1) as seen in A we will show the following features. (I) A differential ageing between (1) and (2) occurs at their reunion and it has an ...

International Nuclear Information System (INIS)

The Jodrell Bank MERLIN array was used to map the OH 1665-and 1667-MHz masers in the circumstellar envelope of U Orionis in 1984, 1986 and 1987. The OH masers lie within a region of extent 130 x 180 AU"2, and have complex distribtuions which are different for each line and polarization. The masers show clumpy structures with a typical clump size of #approx# 25 AU. The strongest emission is from a ring of radius 60 AU which we interpret as part of an expanding, tilted torus. Proper motions have been measured for the OH masers on the ring. The ring has a proper motion of 5.4#+-#1.4 mass yr"-"1 corresponding to a transverse expansion velocity of #approx# 7 km s"-"1 for the period-luminosity distance of U Orionis of 260 pc. (author).

British Library Electronic Table of Contents (United Kingdom)

An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ?? ?(T ?1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum decel...

Science.gov (United States)

The transport of magnetospheric particles in the outer cusp region is examined by means of three-dimensional single particle codes. It is shown that, at high altitudes, particles can experience nonadiabatic motions leading to significant magnetic moment changes. It is demonstrated that this nonadiabatic behavior can be interpreted, at least partly, by the action of an impulsive centrifugal force perturbing the particle gyromotion. Systematic trajectory calculations reveal that plasma sheet ions which ExB convert toward the magnetopause from low L-shells in the dayside sector are subjected to such nonadiabatic motions. As a result of magnetic moment damping, a number of them are injected into the loss cone and subsequently precipitate near the cusp equatorward edge.

CERN Document Server

A new mathematical framework is formulated to derive the effective equations of motion for the constrained quantum system which possesses an internal clock. In the realm close to classical behavior, the quantum evolution is approximated by a finite system of coupled but ordinary differential equations adhered to the weakly imposed Hamiltonian constraint. For the simplified version of loop quantum cosmology in the Bianchi I model with a free massless scalar filed, the resulting effective equations of motion affirm the bouncing scenario predicted by the previous studies: The big bang singularity is resolved and replaced by the big bounces, which take place up to three times, once in each diagonal direction, whenever the directional density approaches the critical value in the regime of Planckian density. It is also revealed that back-reaction arises from the quantum corrections and modifies the precise value of the directional density at the ...

Science.gov (United States)

Motion Camouflage (MC) is illuminated as a novel strategy in counterattacking anti-satellite by way of stealth trajectory scheduling. The dynamics model of MC in space is developed and a quadratic function with three boundary constraints is employed for trajectory determination. Based on the model a scenario is set to run the simulation. The results indicate given the designed acceleration input, the predator will be moved following a prescribed route, which precisely locates the predator between two objects at each time instant. In the last approaching phase, the motion is achieved with a big bumping rate which guarantees the power of this striking. Methods for deriving minimum fuel cost in the fixed approaching duration and the minimum approaching duration in limited acceleration input are proposed and are verified in the simulation. At last, camouflage is recognized as a multi-faceted affair, in which stealth trajectory design is considered ...

International Nuclear Information System (INIS)

The observation by inelastic neutron scattering techniques of a high energy peak in the phonon spectrum (14 THz) of V_3Si is reported, and is attributed to a peak in the phonon density of states due to vanadium motions by the incoherent inelastic neutron scattering process.

UK PubMed Central (United Kingdom)

Natural abundance 13C solid-state nuclear magnetic resonance spectroscopy was used to investigate the effect of the incorporation of cholesterol on the dynamics of dimyristoylphosphatidylcholine (DMPC)...Full Text Available

UK PubMed Central (United Kingdom)

The relationships between muscle tensions, jaw motions, bite and joint forces, and craniofacial morphology are not fully understood. Three-dimensional (3-D) computer models are able to combine anatomical...Full Text Available

UK PubMed Central (United Kingdom)

Four of seven human male subjects developed full penile erections when exposed to erotically stimulating motion pictures. Changes in penile size were detected by a mercury strain gauge transducer and...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

It is shown that a relativistic point kinematics with one independent dilation of (scalar) proper time for each spatial freedom degree would give a really rigorous physical significance to the ordinary logical resolution of the clock paradox between systems in relative motion.

UK PubMed Central (United Kingdom)

Double cones (DCs) are the most common cone types in fish, reptiles and birds. It has been suggested that DCs are used for achromatic tasks such as luminance, motion and polarization vision. Here we...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundMost retinal ganglion cells (RGCs) convey contrast and motion information to visual brain centers. Approximately 2% of RGCs are intrinsically photosensitive (ipRGCs), express...Full Text Available

UK PubMed Central (United Kingdom)

A high-speed fiber-based network for the transmission and display of digitized full-motion cardiac images has been developed. Based on Asynchronous Transfer Mode (ATM), the network is scaleable, meaning...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The detailed features of the calculated energy-level schemes and of thesingle-particle, orbit-occupancy properties of the low-lying levels of the/ital N/=50 isotones /sup 80/Zn, /sup 81/Ga,/sup 82/Ge, /sup 83/As, /sup 84/Se,/sup 85/Br, /sup 86/Kr, and /sup 87/Rb arepresented and discussed. These results are obtained with a new effectiveHamiltonian operator obtained empirically from an iterative fit to experimentalenergies taken from all experimentally studied (/ital A/=82--96)/ital N/=50 nuclei. The model space for the calculations consists ofactive 0/ital f//sub 5/2/, 1/ital p//sub 3/2/,1/ital p//sub 1/2/, and 0/ital g//sub 9/2/ proton orbits relativeto a nominal /sup 78/Ni core. This space is truncated internally byrestricting the number of particles excited from the negative-parity orbitsinto the /ital g//sub 9/2/ orbit to be no greater than four. The typicalstructures predicted for these lighter /ital N/=50 isotones are ...

Energy Technology Data Exchange (ETDEWEB)

There are various reasons for preferring local (e.g., three bump) orbit correction methods to global corrections. One is the difficulty of solving the mN equations for the required mN correcting bumps, where N is the number of superperiods and m is the number of bumps per superperiod. The latter is not a valid reason for avoiding global corrections, since, we can take advantage of the superperiod symmetry to reduce the mN simultaneous equations to N separate problems, each involving only m simultaneous equations. Previously, I have shown how to solve the general problem when the machine contains unknown magnet errors of known probability distribution; we made measurements of known precision of the orbit displacements at a set of points, and we wish to apply correcting bumps to minimize the weighted rms orbit deviations. In this report, we will consider two simpler problems, using similar methods. We consider the case when ...

Energy Technology Data Exchange (ETDEWEB)

Bubbly and slug flows have been analyzed using the afore-mentioned techniques. An image series of bubbly-slug flow is shown. The image separation time is 17 ms, and the total flow length is {approx} 10 cm. A circular eddy pattern that follows the slug can be readily seen and tracked, although reliability is low due to motion in the transverse direction. This motion also adds considerable error to the velocity measurements using image recognition technique. This will increase the reliability and accuracy of the tracking method.

Energy Technology Data Exchange (ETDEWEB)

We have studied the effects of temperature fluctuations on the Advanced Light Source (ALS). By modeling the storage ring support structure, we find that fluctuations of {plus minus}2 to 3deg C in the tunnel will cause photon beam motion of the order of the beam size. Temperature stabilization at this level will allow the residual motion of the photon beams to be reduced by a second level of active feedback, operating on signals from photon beam position monitors. Air temperature in the experimental area and the temperature of cooling water serving the beamlines should be constant to {plus minus}1deg C. This will provide a suitable environment for experiments. (orig.).

CERN Document Server

We study quantum Darwinism -- the redundant recording of information about a decohering system by its environment -- in zero-temperature quantum Brownian motion. An initially nonlocal quantum state leaves a record whose redundancy increases rapidly with its spatial extent. Significant delocalization (e.g., a Schroedinger's Cat state) causes high redundancy: many observers can measure the system's position without perturbing it. This explains the objective (i.e. classical) existence of einselected, decoherence-resistant pointer states of macroscopic objects.

British Library Electronic Table of Contents (United Kingdom)

This paper deals with dynamical behavior of a nonlinear suspension system. We examine chaotic motion in a vehicle suspension system with hysteretic nonlinearity excited by a road profile. A one degree of freedom quarter-car model with nonsymmetric potential is investigated. The Melnikov criterion is used to study the intersection of stable and unstable manifolds and transition to chaos for the system. The condition for chaotic vibration is found using a Melnikov function. Chaotic motion also is indicated by a bifurcation diagram and Lyapunov exponents.

International Nuclear Information System (INIS)

Background: High-resolution computed tomography is the image procedure of choice in the evaluation of interstitial lung disease. Multidetector-row computed tomography provides the possibility of simultaneous reconstruction of thin and thick slices from the same raw data, acquired from one single series. Thus, it may be tempting to exclude the step-and-shoot series. Purpose: To compare high-resolution computed tomography (HRCT step-and-shoot) from single-slice CT (SSCT) and 16-channel multidetector CT (MDCT) in terms of visibility and motion artifacts, and to investigate whether thin images reconstructed from helical MDCT are equal to or better than conventional HRCT by SSCT in terms of visibility and motion artifacts. Material and Methods: 20 patients underwent HRCT step-and-shoot by SSCT (SSCT step-and-shoot) and MDCT (MDCT step-and-shoot), and a helical MDCT acquisition (MDCT helical). Images from four anatomical levels were analyzed in ...

CERN Document Server

Simple, one-zone models for inhomogeneous chemical evolution of the Galactic halo are used to predict the number fraction of zero-metallicity, Population III stars, which currently is empirically estimated at < 4e-4. These analytic models minimize the number of free parameters, highlighting the most fundamental constraints on halo evolution. There are disagreements of at least an order of magnitude between observations and predictions in limiting cases for both homogeneous Simple Model and Simple Inhomogeneous Model (SIM). Hence, this demonstrates a quantitative, unambiguous discrepancy in the observed and expected fraction of Population III stars. We explore how the metallicity distribution of the parent enrichment events f(z_0) drives the SIM and predictions for the Population III fraction. The SIM shows that the previously-identified "high halo" and "low halo" populations are consistent with a continuous evolutionary progression, and therefore may not ...

Energy Technology Data Exchange (ETDEWEB)

In this talk, we summarize recent results obtained from the combined neutrino telescopes IceCube and AMANDA. The combined approach, including data taken from both detectors simultaneously, is compared to other analyses that are using IceCube only data. The main benefit of the combined detector is its improved performance at low energies, meaning energies below 1 TeV (close to the energy threshold of the detector). The discussion is focused on the search for extra-terrestrial neutrinos from candidate sources in our Galaxy. Using appropriate cuts, the sensitivity can be optimized for soft spectra neutrino sources. With the resulting data sample, several studies are performed: an unbinned Galactic Plane Scan and a Cygnus region analysis: the Multi Point Source analysis. The current status of these analyses is presented.

CERN Document Server

Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. The excess of diffuse Galactic Gamma Rays from EGRET shows all the features expected from DMA. The new precise measurements of the antiproton and positron fractions from PAMELA are compared with the EGRET excess. It is shown that the charged particles are strongly dependent on the propagation model used. The usual propagation models with isotropic propagation models are incompatible with the recently observed convection in our Galaxy. Convection leads to an order of magnitude uncertainty in the yield of charged particles from DMA, since even a rather small convection will let drift the charged particles in the halo to outer space. It is shown that such anisotropic propagation models including convection prefer a contribution from DMA for the antiprotons, but the rise in the positron fraction, ...

Energy Technology Data Exchange (ETDEWEB)

Researchers report results from the Low Energy Antiproton Experiment (LEAP), a balloon-borne instrument which was flown in August, 1987. They found a value of 4.2 by 10-6 for the antiproton to proton ratio in the energy range from 120 MeV to 600 MeV at the top of the atmosphere. In particular, this experiment places an upper limit on the flux almost an order of magnitude below the reported flux of Buffington et al. This upper limit allows us to place significant constraints on both the primordial black hole and weakly interacting Majorana Fermion hypothesis, as well as on the low energy processes in more conventional models of galactic cosmic ray antiproton production.

British Library Electronic Table of Contents (United Kingdom)

Abstract Recent work (Schawinski et al.) indicates that star-forming early-type galaxies residing in the blue cloud migrate rapidly to the red sequence within around a Gyr, passing through several phases of increasingly strong active galactic nucleus (AGN) activity in the process. We show that natural depletion of the cold gas reservoir through star formation (i.e. in the absence of any feedback from the AGN) induces a blue-to-red reddening rate that is several factors lower than that observed by Schawinski et al. This is because the gas depletion rate due to star formation alone is too slow, implying that another process needs to be invoked to remove cold gas from the system and accelerate the reddening rate. We develop a simple phenomenological model, in which a fraction of the AGN-s lum...

CERN Document Server

We present a large set of merger simulations of early-type disc galaxies with mass ratios of 1:1 and 3:1 and 10% of the total disc mass in gas. In contrast to the collisionless case equal-mass mergers with gas do not result in very boxy remnants which is caused by the suppression of box orbits and the change of the projected shape of minor-axis tube orbits in the more axisymmetric remnants. The isophotal shape of 3:1 remnants and the global kinematic properties of 1:1 and 3:1 remnants are only weakly affected by the presence of gas. 1:1 remnants are slowly rotating whereas 3:1 remnants are fast rotating and discy. The shape of the stellar LOSVD is strongly influenced by gas. The LOSVDs of collisionless remnants have broad leading wings while their gaseous counterparts show steep leading wings, more consistent with observations of elliptical galaxies. We show that this change is also caused by the suppressed populating of box ...

International Nuclear Information System (INIS)

For the first time a comprehensive level and decay scheme has been obtained for a T=(5/2) nucleus in the s-d shell ("2"7Na) by using a radioactive beam and target. Particle-#gamma# and p-#gamma#-#gamma# coincidences were measured following the "1"4C("1"4C,p#gamma#)"2"7Na reaction at E_l_a_b=22 MeV. The results do not support an inversion of the 2s_1_/_2 and 1d_5_/_2 orbitals, as previously proposed for T_z#>=#3, but they do suggest an increased N=16 gap between the 2s_1_/_2 and 1d_3_/_2 orbitals due to the neutron excess. A consistent interpretation of the level scheme in terms of the s-d shell model using the USD Hamiltonian is possible below 4 MeV, but differences increase at higher excitation energies. Another interpretation is that the influences of both the p_1_/_2 and f_7_/_2 intruder orbitals increase simultaneously with increasing T, an effect not included in the USD Hamiltonian.

International Nuclear Information System (INIS)

The dynamics of a general Bianchi type-IX model with three scale factors is examined. The matter content of the model is assumed to be comoving dust plus a positive cosmological constant. The model presents a critical point of saddle-center-center type in the finite region of phase space. This critical point engenders in the phase space dynamics the topology of stable and unstable four dimensional tubes RxS"3, where R is a saddle direction and S"3 is the manifold of unstable periodic orbits in the center-center sector. A general characteristic of the dynamical flow is an oscillatory mode about orbits of an invariant plane of the dynamics which contains the critical point and a Friedmann-Robertson-Walker (FRW) singularity. We show that a pair of tubes (one stable, one unstable) emerging from the neighborhood of the critical point towards the FRW singularity have homoclinic transversal crossings. The homoclinic intersection manifold has topology ...

CERN Document Server

We report the first direct detection of an exoplanet in polarized scattered light. The transiting planet HD189733b is one of the very hot Jupiters with shortest periods and, thus, smallest orbits, which makes them ideal candidates for polarimetric detections. We obtained polarimetric measurements of HD189733 in the $B$ band well distributed over the orbital period and detected two polarization maxima near planetary elongations with the peak amplitude of $\\sim2\\cdot10^{-4}$. Assuming Rayleigh scattering, we estimated the effective size of the scattering atmosphere (Lambert sphere) to be 1.5$\\pm$0.2 $R_{\\rm J}$, which is 30% larger than the radius of the opaque body previously inferred from transits. If the scattering matter fills the planetary Roche lobe, the lower limit of the geometrical albedo can be estimated as 0.14. The phase dependence of polarization indicates that the planetary orbit is oriented almost in the ...

International Nuclear Information System (INIS)

We report de Haas--van Alphen measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare-earth elements from Gd to Tm. The fact that no complete frequency branches were observed indicates that there are no closed pieces of the Fermi surface. We observed all but one orbit predicted by relativistic augmented-plane-wave calculations of Keeton and Loucks and by recent spin-orbit--linearized-augmented-plane-wave calculations of Tibbetts and Harmon. The data support a geometry similar to that of yttrium, and in good qualitative agreement with energy-band theory.

International Nuclear Information System (INIS)

A measurement of the magnetic form factor of a ferromagnetic actinide compound of UTe with circularly polarized X-rays is reported. The present geometrical configuration of the measurement gives a form factor of L(k)+0.3S(k), where L(k) and S(k) are the form factors of the orbital and the spin magnetic moment, respectively. We have combined the X-ray magnetic form factor with the neutron one which gives L(k)+2S(k) (G. Busch et al.: J. Phys. C 12 (1979) 1391), and have deduced L(k) and S(k) separately. The obtained profiles of L(k) and S(k) show that the orbital and the spin magnetic moments are spatially spread out more than those calculated for a free uranium ion. (author).

Energy Technology Data Exchange (ETDEWEB)

The possibility of controlling the radial electric field of toroidal plasmas by injecting high energy electrons along the reversible loss cone orbit of the helical magnetic traps is investigated. It is well known that the radial electric field plays an important role in the confinement improvement scenario especially in the low collisional regime under the physics picture of neoclassical theory. For this purpose, it is made clear that the most suitable particles are transit particles, which show a transition from helically trapped orbits to blocked ones. It is also found that a parallel AC electric field launched from outside assists this transition and makes it possible for particles to penetrate deeply into the plasma. In addition we clarify that the viscosity of the plasma coupled with the helical field configuration provide a bifurcation of plasma states and its stable solution results in confinement improvement. (author)

International Nuclear Information System (INIS)

By using a variational Monte Carlo method, we examine an effective low-energy model for LaFeAsO derived from an ab initio downfolding scheme. We show that quantum and many-body fluctuations near the antiferromagnetic (AF) quantum critical point largely reduce the antiferromagnetic ordered moment. Our derived model not only quantitatively reproduces the small ordered moment in LaFeAsO, but also accounts for the diversity from LaFePO, BaFe_2As_2 to FeTe. Electron correlation is found to determine the observed material dependence. We also find that LaFeAsO is subject to large orbital fluctuations, sandwiched by the AF Mott insulator and weakly correlated metals. The orbital fluctuations and Dirac-cone dispersion hold keys for the diverse magnetic properties. (author)

CERN Document Server

The hyperfine interactions at the uranium site in the antiferromagnetic USb2 compound were calculated within the density functional theory (DFT) employing the augmented plane wave plus local orbital (APW+lo) method. We investigated the dependence of the nuclear quadruple interactions to the magnetic structure in USb2 compound. The investigation were performed applying the so called band correlated LDA+U theory self consistently. The self consistent LDA+U calculations were gradually added to the performed generalized gradient approximation (GGA) including scalar relativistic spin orbit interactions in a second variation scheme. The result, which is in agreement with experiment, shows that the 5f-electrons have the tendency to be hybridized with the conduction electrons in the ferromagnetic uranium planes.

DEFF Research Database (Denmark)

Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longer than 75 days.

International Nuclear Information System (INIS)

Space particles act on semiconductor devices by creating charges (electrons, holes) in the silicon and the silicon dioxide, and by creating displacement damage. These primary phenomena alter the electrical parameters of MOS and bipolar devices (threshold voltage V_t, mobility #mu#, conductivity #sigma#, current gain #beta#). The dose rate is not important in space (a few rad (Si)/h) but as the durations of space expeditions are on average from seven to twelve years, the total dose is an aggravating factor in the behaviour of the electrical parameters and also in device operation. The total dose effect from the beginning of charge creation (ionization) to the parameter shifts is reviewed. One can note that this effect is permanent because there will almost always be charge creation in space. Another important phenomenon is called the Single Event Upset (S.E.U.) and caused by the heavy ions and the protons which come from the galactic rays. The consequence of S.E.U. ...

International Nuclear Information System (INIS)

The oxygen vacancies distribution in the rigid lattice and the thermally activated motion of oxygen atoms are studied in La1-xSrxGa1-xMgxO3-x (x=0.00; 0.05; 0.10; 0.15 and 0.20) compounds. For that 71Ga, 25Mg and 17O NMR was performed from 100 K up to 670 K, and ion conductivity measurements were carried out up to 1273 K. The comparison of the electric field gradients at the Ga- and Mg-sites evidences that oxygen vacancies appear exclusively near gallium cations as a species trapped below room temperature in local clusters, GaO5/2-#square#-GaO5/2. These clusters decay at higher temperature into mobile constituents of the structural octahedra Ga(O5/6#square#1/6)6/2. At the same time, the nearest octahedral oxygen environment of magnesium cations persists at different doping levels. The case of two adjacent vacant anion sites is found highly unlikely within the studied doping range. The thermally activated oxygen motion starts to develop above ...

Energy Technology Data Exchange (ETDEWEB)

The palladium(II) and platinum(II)complexes(where, (M(L){sub 2}X{sub 2}), M=Pd(II), Pt(II); L=isoxazole (isox), 3, 5-dimethylisoxazole(3, 5-diMeisox), 3-methyl, 5-phenylisoxazole(3-Me, 5-Ph-isox), and 4-amino-3, 5-di-methylisoxazole (4-ADI); X=Cl, Br) with isoxazole and its derivatives were investigated on antitumor activity by MM2 and EHMO calculation. Because for all the complexes the {sigma}MO energy level (E{sub {sigma}}{sub (M-X)} between d{sub x}{sup 2}{sub -y}{sup 2} orbital of central metal and p{sub x} orbital of halogen atom is less than {sigma}MO energy level E{sub {sigma}}{sub (M-N)} between d{sub x}{sup 2}{sub -y}{sup 2} orbital of central metal and p{sub x} orbital of N atom, without exception. And judging, from the lower E{sub {sigma}}{sub (M-X)} value in trans, the bonding strength was found to be weaker in trans isomer than in cis. For the Pd(II) and Pt(II) complexes which have planar ...

Energy Technology Data Exchange (ETDEWEB)

Heavy-ion reaction with unstable nuclei, {sup 13}N and {sup 11}Be, {sup 13}N+{sup 12}C and {sup 11}Be+{sup 12}C-{sup 10}Be+{sup 13}C were analyzed by a coupled-reaction-channel (CRC) method and formation of valence nucleon molecular orbital was studied by numerical analysing calculation. In this report, 1P1/2 (the ground state of {sup 13}N and {sup 13}C), 2s1/2 (the ground state of {sup 11}Be), 1d5/2 and 1d3/2 orbital were studied as one particle state of valance nucleon in {sup 13}N, {sup 13}C and {sup 11}Be. Moreover, d3/2 state, comparatively higher excited state, was contained into CRC calculation. The effect of this state on CRC scheme was proved very large. We developed new program code to obtain the numerical stable solution. It is necessary to about 200 MB (CRC equation) for {sup 11}Be+{sup 12}C{yields}{sup 10}Be+{sup 13}C and about 300 MB for discussion about molecular orbital. We show that the CRC calculation with ...

International Nuclear Information System (INIS)

An internuclear cascade-evaporation code is used to model energy deposition in thin slabs of silicon. This model shows that protons produce a significant number of events with effective Linear Energy Transfer (LET) greater than 8 MeV cm"2/mg and demonstrates that proton testing of microelectronic components can be an effective way to screen devices for low earth orbit susceptibility to heavy ions.

International Nuclear Information System (INIS)

The crystal structure, lattice strain due to the antiferromagnetic ordering, and magnetic form factor in the itinerant 5f compounds UTGa_5 (T=Ni, Pd, Pt) have been studied by neutron scattering. High-resolution powder diffraction revealed that the tetragonality of the U-Ga layers increases down to the series of the transition metal element T. The integrated intensities of the antiferromagnetic reflections can be well explained with the Neel-type structure for UNiGa_5, whereas UPtGa_5 has the antiferromagnetic stacking of the ferromagnetically ordered uranium moments in the c plane. In both compounds the uranium moments orient along the c axis with moments of 0.75(5) and 0.32(5) #mu#_B for UNiGa_5 and UPtGa_5, respectively. No magnetic peak could be observed in the powder diffraction pattern of UPdGa_5 due to the small magnetic moment less than the experimental sensitivity. The orbital contributions in the magnetic form factor are reduced from the free-ion value, ...

International Nuclear Information System (INIS)

The Guarantee Outline presents the technical demands of design and contents of assessment for radiation hardening in satellite engineering in China. It includes the basis of design in space environment of polar orbit, the contents of design for general radiation hardening, the requirements and assessments of the single-board computer, the requirements of design for circuits (including hardware and software), the choices and assessments for devices, and the primary stipulations for the requirements of design and assessments against the phenomenon of charge and discharge.

CERN Document Server

Dimensional metrology and positioning operations are used in many fields of particle accelerator projects. This lecture gives the basic tools to designers in the field of measure by analysing the spatial layout of measurement systems since it is central to dimensional metrology as well as positioning operations. In a second part, a case study dedicated to a synchrotron storage ring is proposed from the detection of the magnetic centre of quadrupoles to the orbit definition of the ring.

International Nuclear Information System (INIS)

Passive dosimeters for personal and area radiation monitor in space have been developed mainly for dosimetry in low-earth-orbit (LEO) radiation environments of Space Shuttles and the International Space Station. The responses of several dosimeters have been evaluated by heavy ions and also its variation for individual dosimeter element. (author)

International Nuclear Information System (INIS)

Calculations of the Compton profiles for the transition metals Ta and W are performed, using electron wave functions obtained from self-consistent augmented plane wave (APW) band structure calculations within the local density formalism of Hedin-Lundqvist. Relativistic effects are included except for the spin-orbit interaction. The observed structures of the Compton profiles in these metals are understood in terms of the topology of their Fermi surfaces. (author).

International Nuclear Information System (INIS)

3d occupation numbers of the transition elements corresponding to various types of atomic configurations are calculated by means of the linear muffin-tin orbital (LMTO) method. This data is used with the multiconfiguration Dirac-Fock (MCDF) X-ray intensity ratios to estimate the electron populations of the 3d metals in alloys.

Environmental Research Database

DescriptionRemote sensing of the sea surface from satellites in near-polar orbits has contributed greatly to our understanding of the links between physical and biological processes in marine systems. However most of this progress has been made in open oceanic waters or major upwelling areas, and many unresolved problems are encountered in coastal regions and shelf seas. In these optically complex waters, quantitative remote sensing requires a more sophisticated interpretation strategy than that implemente [continued...

CERN Document Server

The third US Naval Observatory (USNO) CCD Astrograph Catalog, UCAC3 was released at the IAU General Assembly on 2009 August 10. It is the first all-sky release in this series and contains just over 100 million objects, about 95 million of them with proper motions, covering about R = 8 to 16 magnitudes. Current epoch positions are obtained from the observations with the 20 cm aperture USNO Astrograph's "red lens", equipped with a 4k by 4k CCD. Proper motions are derived by combining these observations with over 140 ground- and space-based catalogs, including Hipparcos/Tycho and the AC2000.2, as well as unpublished measures of over 5000 plates from other astrographs. For most of the faint stars in the Southern Hemisphere the Yale/San Juan first epoch plates from the SPM program (YSJ1) form the basis for proper motions. These data are supplemented by all-sky Schmidt plate survey astrometry and photometry obtained from the ...

Energy Technology Data Exchange (ETDEWEB)

The United States Air Force School of Aerospace Medicine (USAFSAM) tests the quantitative fit of masks which are worn by military personnel during nuclear, biological, and chemical warfare. Subjects are placed in a Dynatech-Frontier Fit Testing Chamber, salt air is fed into the chamber, and samples of air are drawn from the mask and the chamber. The ratio of salt air outside the mask to salt air inside the mask is called the quantitative fit factor. A motion-time study was conducted to evaluate the efficiency of the layout and work method presently used in the laboratory. A link analysis was done to determine equipment priorities, and the link data and design guidelines were used to develop three proposed laboratory designs. The proposals were evaluated by projecting the time and motion efficiency, and the energy expended working in each design. Also evaluated were the lengths of the equipment links for each proposal, and each ...

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the buffeting of a slender, circular, flexible beam-rod in an axial turbulent flow. The principal excitation mechanisms are the turbulent wall pressure fluctuations and the motion-dependent (self-excited) aerodynamic force caused by the beam motion. On the assumption that the turbulent wall pressure fluctuations are independent of the beam motion, a linear forced-vibration model is used to determine the buffeting response of the beam and to investigate the length scale effects of turbulences on the beam buffeting. Transverse buffeting of the beam in an axial turbulent flow depends largely on the ratio of the longitudinal scale of the turbulences to the bending wavelength of the beam and on the ratio of the circumferential scale of the turbulences to the radius of the beam. The spectra and the mean square values of the buffeting displacement of the beam become vanishingly small, both when either of ...

International Nuclear Information System (INIS)

The clinical courses of heterotopic ossification (HO) as a consequence of trauma and central nervous system insults have many similarities as well as dissimilarities. Detection is commonly noted at two months. The incidence of clinically significant HO is 10%-20%. Approximately 10% of the HO is massive and causes severe restriction in joint motion or ankylosis. The most common sign and symptom are decreased range of motion and pain. The locations are the proximal limbs and joints. Sites of HO about a joint may vary according to the etiology of the HO. Roentgenographic evolution of HO occurs during a six-month period in the majority of patients. Treatment modalities include diphosphonates, indomethacin, radiation, range of motion exercises, and surgical excision. Surgical timing differs according to etiology: traumatic HO may be resected at six months; spinal cord injury HO is excised at one year; and traumatic brain injury ...

International Nuclear Information System (INIS)

Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on "4"0Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).

International Nuclear Information System (INIS)

Constrained least-squares techniques have been used to produce a well known class of image restoration algorithms. These techniques typically involve minimizing a linear operator on a vector representation of an image, subject to a constraint. For cases where an equality constraint is appropriate the method of Lagrange multipliers can be used to produce a restored image. In this work a fractal textural model, fractional Brownian motion, is used to represent images of interest. Using a variance fractal dimension estimator a non-linear operator, that represents the squared difference between the fractal dimension of the restored image and on a priori value is minimized, subject to the constraint that the norm of the residual between the restored image and available measurement equal the norm of the additive noise.

International Nuclear Information System (INIS)

The thermal conductivity of liquid CHCl3, C6H6, and CCl4 is measured by a steady-state method under saturated vapor pressure in the temperature regions corresponding to pre-crystallization temperatures. The experimental results obtained are used to investigate the isobaric thermal conductivity jump ? ?p at the crystal-liquid phase transition in CHCl3, C6H6, and CCl4. The contributions of the phonon-phonon and phonon-rotational interaction to the total thermal resistance in solid and liquid state are specified using a modified method of reduced coordinates. The decrease in the thermal conductivity at the crystal-liquid phase transition, ? ?p, is explained by a combined effect of variations in positional distribution of molecules and in the form of rotational molecular motion.

Science.gov (United States)

A theory for the mass transfer process was developed. It was assumed that the largest convective motions in the flow control the rate of mass transfer. Measurements of mass transfer coefficients for the absorption of oxygen by water films were made for concurrent flows in a horizontal rectangular channel, and for concurrent and free-falling downflow in a one-inch pipe. The measured values of the Sherwood number for concurrent flows were up to three times as great as would be predicted from this relation. This increase in Sherwood number was correlated with a dimensionless group similar to a Martinelli parameter which is characteristic of two phase flows. An explanation for this effect is given in terms of the way that the scales of the convective motions are related to bulk flow parameters.

DEFF Research Database (Denmark)

In this work, we address the problem of road interpretation for driver assistance based on an early cognitive vision system. The structure of a road and the relevant traf?c are interpreted in terms of ego-motion estimation of the car, independently moving objects on the road, lane markers and large scale maps of the road. We make use of temporal and spatial disambiguation mechanisms to increase the reliability of visually extracted 2D and 3D information. This information is then used to interpret the layout of the road by using lane markers that are detected via Bayesian reasoning. We also estimate the ego-motion of the car which is used to create large scale maps of the road and also to detect independently moving objects. Sample results for the presented algorithms are shown on a stereo image sequence, that has been collected from a structured road.

Energy Technology Data Exchange (ETDEWEB)

The switching behavior of magnetic patterns prepared by ion irradiation was investigated. Co/Pt multilayers with perpendicular anisotropy and large out-of-plane coercivities 5-6 kOe were grown on electron transparent SiN windows. Regularly spaced 1 micron sized regions, were magnetically pattered via ion beam irradiation through a stencil mask. Lorentz TEM was used to observe in-situ magnetization reversal processes of irradiated regions under well-defined applied magnetic fields. When the in-plane field was increased, domain wall motion was observed, resulting in the alignment of the patterns with the direction of the applied field. The switching mechanism of the in-plane patterns was by domain wall motion.

Energy Technology Data Exchange (ETDEWEB)

The purpose of this paper is to check up a GPS (global positioning system) impact on scientific research activities of the Geodetic Society of Japan. First, it is mentioned that the conventional geoid-based concept of 'gravity anomaly' should be changed to a new definition, according to the GPS-determined ellipsoidal height system. Secondly, the results of many experiments, which have been made to monitor ocean-plate motions relative to the Japanese island-arcs, demonstrate that GPS is a powerful tool for obtaining temporal changes in horizontal displacement induced by the plate motion. Therefore, it is suggested that terrestrial measurements, such as triangulation and long-range leveling, would be replaced by GPS measurements in near future. Moreover, it is pointed out that GPS geodesy should play an important role in monitoring secular sea level trend due to global warming of the atmosphere and ocean. 19 refs., 4 figs.

Energy Technology Data Exchange (ETDEWEB)

It is the intention of this paper to point to some of the problems due to molecular motion and to suggest a few solutions to those problems. A few examples will be presented of model systems which demonstrate the effects of motion on the NMR spectroscopy and a very qualitative example of severe spectral distortion in fulvic acids will be shown. In the following discussions we will use concepts derived from the oft repeated thermodynamic picture shown in figure 1. When dealing with a homogeneous, pure compound this picture is sufficient but in a heterogeneous mixture, it is likely that there will be different compounds and different domains all with slightly different versions of figure 1 with poor thermodynamic contact between them. Thus optimal conditions for cross polarization in one domain may be totally inappropriate for another. 59 refs., 10 figs.

Energy Technology Data Exchange (ETDEWEB)

A new semi-submersible floating structure is proposed on which three wind turbine towers are installed. This paper presents a basic characteristic of the wave-induced motion of this semi-submersible floating structure via. numerical computations and 1/150 scaled rigid model experiments in a wave tank. In the numerical computations, nonlinear damping effect due to drag forces modeled by the Morison's formula is considered in the equation of motion, where the linear hydrodynamic forces are obtained from the Green's function model. As a result, the response characteristics around the resonant frequency region were successfully improved. In addition to such basic examination, major results of feasibility studies, including the structural stability for severe wave conditions and the long-term fatigue limit state, are presented for a realistic situation.

CERN Document Server

In the next decade Type Ia supernovae (SNe Ia) will be used to test theories predicting changes in the Dark Energy equation of state with time. Ultimately this requires a dedicated space mission like JDEM. SNe Ia are mature cosmological probes --- their limitations are well characterized, and a path to improvement is clear. Dominant systematic errors include photometric calibration, selection effects, reddening, and population-dependent differences. Building on past lessons, well-controlled new surveys are poised to make strides in these areas: the Palomar Transient Factory, Skymapper, La Silla QUEST, Pan-STARRS, the Dark Energy Survey, LSST, and JDEM. They will obviate historical calibrations and selection biases, and allow comparisons via large subsamples. Some systematics follow from our ignorance of SN Ia progenitors, which there is hope of determining with SN Ia rate studies from 0galactic and cluster chemical ...

CERN Document Server

We present a detailed spectral analysis of point-like X-ray sources in the XMM-COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%).As expected, the distribution of intrinsic absorbing column densities is markedly different between AGN with or without broad optical emission lines. We find within our sample four Type-2 QSOs candidates (L_X > 10^44 erg/s, N_H > 10^22 cm^-2), with a spectral energy distribution well reproduced by a composite Seyfert-2 spectrum, that demonstrates the strength of the wide field XMM/COSMOS survey to detect these rare and underrepresented sources.

CERN Document Server

We present our discovery of a narrow-line Baldwin effect, an anti-correlation between the equivalent width (EW) of a line and the flux of the associated continuum, in 5-20$\\mu$m mid-infared lines from a sample of 68 Active Galactic Nuclei (AGN), located at z$<$0.5, observed with the Infrared Spectrograph on the {\\it Spitzer Space Telescope}. Our analysis reveals a clear anti-correlation between the EW of the [SIV] 10.51$\\mu$m, [NeII] 12.81$\\mu$m, and [NeIII] 15.56$\\mu$m lines and their mid-IR continuum luminosities, while the Baldwin effect for [NeV] 14.32$\\mu$m is not as obvious. We suggest that this anti-correlation is driven by the central AGN and not circumnuclear star formation in the host galaxy. We also find that the slope of the narrow-line Baldwin effect in the mid-infrared does not appear to steepen with increasing ionization potential. Examining the dependence of the EW to the Eddington Ratio ($L/L_{Edd}$) we find no strong relationship for ...

CERN Document Server

We numerically investigate whether and how gaseous ejecta from AGB stars can be converted into new stars within originally massive star clusters (MSCs) in order to understand the origin of multiple stellar populations in globular clusters (GCs). We adopt a scenario in which (i) MSCs with masses of M_s can be formed from high-mass, high-density giant molecular clouds (GMCs) in their host galactic building blocks embedded in dark matter halos at high redshifts and (ii) their evolution therefore can be significantly influenced by M_s, their initial locations, and physical properties of their hosts. Our 3D hydrodynamical simulations show that gaseous ejecta from AGB stars can be retained within MSCs and consequently converted into new stars very efficiently in the central regions of MSCs, only if M_s exceed a threshold mass (M_th) of ~10^6 M_sun. The new stars can correspond to the ``second generation (SG)'' of stars with higher Na and lower O abundances observed in ...

Energy Technology Data Exchange (ETDEWEB)

The X-ray spectra of {approx}200 AGN collected from Swift-BAT were analyzed to test the Unified Model for AGN. Specifically, the photon indices, high energy cutoffs, and reflection components of Sy1 and Sy2 were compared. Under the Unified Model, the photon indices and reflection components for Sy1 should be larger than Sy2 and the high energy cutoffs should be the same. Fitting a simple power law model to the sample spectra proved to be insufficient. The PEXRAV model fit the spectra of the Sy1 and Sy2 significantly better, indicating that a reflection component and/or high energy cutoff exists as the Unified Model expects. Using both the simple power law and PEXRAV models it was concluded that in the population studied, Sy1 had a larger photon index than Sy2, as expected by the Unified Model. For Sy1 and Sy2, the reflection components were found to be compatible, but given the large errors, this finding cannot be said to be evidence against the Unified Model. However, it was concluded ...

CERN Document Server

Primordial black holes are unique probes of cosmology, general relativity, quantum gravity and non standard particle physics. They can be considered as the ultimate particle accelerator in their last (explosive) moments since they are supposed to reach, very briefly, the Planck temperature. Upper limits on the primordial black hole number density of mass $M_{\\star} = 5 10^{14}$ g, the Hawking mass (born in the big-bang terminating their life presently), is determined comparing their predicted cumulative $\\gamma$-ray emission, galaxy-wise, to the one observed by the EGRET satellite, once corrected for non thermal $\\gamma$-ray background emission induced by cosmic ray protons and electrons interacting with light and matter in the Milky Way. A model with free gas emissivities is used to map the Galaxy in the 100 MeV photon range, where the peak of the primordial black hole emission is expected. The best gas emissivities and additional model parameters are obtained by fitting the EGRET ...

CERN Document Server

The narrow emission line spectra of active galactic nuclei are not accurately described by simple photoionization models of single clouds. Recent Hubble Space Telescope images of Seyfert 2 galaxies show that these objects are rich with ionization cones, knots, filaments, and strands of ionized gas. Here we extend to the narrow line region the ``locally optimally emitting cloud'' (LOC) model, in which the observed spectra are predominantly determined by powerful selection effects. We present a large grid of photoionization models covering a wide range of physical conditions and show the optimal conditions for producing many of the strongest emission lines. We show that the integrated narrow line spectrum can be predicted by an integration of an ensemble of clouds, and we present these results in the form of diagnostic line ratio diagrams making comparisons with observations. We also predict key diagnostic line ratios as a function of distance from the ionizing ...

CERN Document Server

Anti-proton and positron Galactic cosmic ray (GCR) spectra are among the key targets for indirect detection of dark matter (DM). The boost factors, corresponding to an enhancement of the signal|linked to the clumpiness properties of the dark matter distribution|, have been taken as high as thousands in the past. The dramatic impact of these boost factors for indirect detection of antiparticles, for instance with the PAMELA satellite or the coming AMS-02 experiment, asks for their detailed calculation. We take into account the state-of-the-art results of high resolution N-body dark matter simulations to calculate the most likely energy dependent boost factors|linked to the GCR propagation properties|, for anti-protons and positrons. The results from extreme, but still possible, configurations of the clumpy dark matter component is also discussed. Starting from the mass and space distributions of sub-halos, the anti-proton and positron propagators are used to ...

CERN Document Server

Some models for quantum gravity (QG) violate Lorentz invariance and predict an energy dependence of the speed of light, leading to a dispersion of high-energy gamma-ray signals that travel over cosmological distances. Limits on the dispersion from short-duration substructures observed in gamma-rays emitted by gamma-ray bursts (GRBs) at cosmological distances have provided interesting bounds on Lorentz invariance violation (LIV). Recent observations of unprecedentedly fast flares in the very-high energy gamma-ray emission of the active galactic nuclei (AGNs) Mkn 501 in 2005 and PKS 2155-304 in 2006 resulted in the most constraining limits on LIV from light-travel observations, approaching the Planck mass scale, at which QG effects are assumed to become important. I review the current status of LIV searches using GRBs and AGN flare events, and discuss limitations of light-travel time analyses and prospects for future instruments in the gamma-ray domain.

International Nuclear Information System (INIS)

Through analysis of archival images and photometry from the Spitzer GLIMPSE and MIPSGAL surveys combined with Two Micron All Sky Survey and MSX data, we have identified 488 candidate young stellar objects (YSOs) in the giant molecular cloud M17 SWex, which extends #approx#50 pc southwest from the prominent Galactic H II region M17. Our sample includes >200 YSOs with masses >3 M _s_u_n that will become B-type stars on the main sequence. Extrapolating over the stellar initial mass function (IMF), we find that M17 SWex contains >1.3 x 10"4 young stars, representing a proto-OB association. The YSO mass function is significantly steeper than the Salpeter IMF, and early O stars are conspicuously absent from M17 SWex. Assuming M17 SWex will form an OB association with a Salpeter IMF, these results reveal the combined effects of (1) more rapid circumstellar disk evolution in more massive YSOs and (2) delayed onset of massive star formation.

Energy Technology Data Exchange (ETDEWEB)

Yet designed to measure charged component of the cosmic rays, the foreseen Alpha Magnetic Spectrometer (AMS-02) could also release {gamma}-ray studies, in the energy range from GeV to TeV, using the tracker system, for {gamma}-rays converted in e{sup +}e{sup -} pair, and the electromagnetic calorimeter. In the first part of the thesis are described the calibrations and the performances of the engineering model of the calorimeter, obtained from the analysis of data taken during a test-beam performed at CERN in July 2002. In the second part of the thesis, the AMS-02 discovery potential for {gamma}-astrophysics is presented. While exposure maps of the {gamma}--sky are computed for one year of data taking with the {gamma}--detectors, the acceptance of the calorimeter is obtained from Monte-Carlo simulations. The AMS-02 potential is then estimated for signals from the Vela pulsar and for some supersymmetric signals from the Galactic Center. (author)

CERN Document Server

We have derived elemental abundances for a sample of nine IRAS sources with colours similar to those of post-AGB stars. For IRAS 01259+6823, IRAS 05208-2035, IRAS 04535+3747 and IRAS 08187-1905 this is the first detailed abundance analysis based upon high resolution spectra. Mild indication of s-processing for IRAS 01259+6823, IRAS 05208-2035 and IRAS 08187-1905 have been found and a more comprehensive study of s-process enhanced objects IRAS 17279-1119 and IRAS 22223+4327 have been carried out. We have also made a contemporary abundance analysis of the high galactic latitude supergiants BD+39 4926 and HD 107369. The former is heavily depleted in refractories and estimated [Zn/H] of -0.7 dex most likely gives initial metallicity of the star. For HD 107369 the abundances of alpha and Fe-peak elements are similar to those of halo objects and moderate deficiency of s-process elements is seen. IRAS 07140-2321 despite being a short period binary with circumstellar shell ...

CERN Document Server

We estimate binary compact object merger detection rates for LIGO, including the binaries formed in ellipticals long ago. Specifically, we convolve hundreds of model realizations of elliptical- and spiral-galaxy population syntheses with a model for elliptical- and spiral-galaxy star formation history as a function of redshift. Our results favor local merger rate densities of 4\\times 10^{-3} {Mpc}^{-3}{Myr}^{-1} for binary black holes (BH), 3\\times 10^{-2} {Mpc}^{-3}{Myr}^{-1} for binary neutron stars (NS), and 10^{-2} {Mpc}^{-3}{Myr}^{-1} for BH-NS binaries. Mergers in elliptical galaxies are a significant fraction of our total estimate for BH-BH and BH-NS detection rates; NS-NS detection rates are dominated by the contribution from spiral galaxies. Using only models that reproduce current observations of Galactic NS-NS binaries, we find slightly higher rates for NS-NS and largely similar ranges for BH-NS and BH-BH binaries. Assuming a detection signal-to-noise ...

CERN Document Server

Accretion processes in quasars and active galactic nuclei are still poorly understood, especially as far as the connection between observed spectral properties and physical parameters is concerned. Quasars show an additional degree of complexity compared to stars that is related to anisotropic emission/obscuration influencing the observed properties in most spectral ranges. This complicating factor has hampered efforts to define the equivalent of an Hertzsprung-Russel diagram for quasars. Even if it has recently become possible to estimate black hole mass and Eddington ratio for sources using optical and UV broad emission lines, the results are still plagued by large uncertainties. Nevertheless, robust trends are emerging from multivariate analysis of large spectral datasets of quasars. A firm observational basis is being laid out by accurate measurements of broad emission line properties especially when the source rest-frame is known. We consider the most widely ...