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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...

CERN Document Server

In a recent paper by Hooper and Goodenough, data from the Fermi Gamma Ray Telescope was analyzed and an excess of gamma rays was found in the emission spectrum from the Galactic Center Region. Hooper and Goodenough show that the excess can be well explained by 7-10 GeV annihilating dark matter with a power law density profile if the dark matter annihilates predominantly to tau pairs. In this paper we present such a dark matter model by extending the MSSM to include four Higgs doublets and one scalar singlet. A Z2 symmetry is imposed that enforces a Yukawa structure so that the up quarks, down quarks, and leptons each receive mass from a distinct doublet. This leads to an enhanced coupling of scalars to leptons and allows the model to naturally achieve the required phenomenology in order to explain the gamma ray excess. Our model yields the correct dark matter thermal relic density and avoids collider bounds from measurements of the Z width as ...

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 ...

International Nuclear Information System (INIS)

This report summarizes the results and activities funded by this three-year award. The principal goal of this project was to determine the thermal conductivity in clusters of galaxies. Intracluster plasmas possess chaotic magnetic fields. Since charged particles are constrained to move primarily along magnetic field lines, the topology of intracluster magnetic fields slows particle diffusion relative to the non-magnetized case, thereby reducing the thermal conductivity. Our first approach to this problem was to employ the static-magnetic-field approximation. In reality, intracluster magnetic field lines are constantly moving, since they are advected by turbulent intracluster motions. The turbulent velocities, however, are much smaller than the rapid speeds of thermal electrons, which make the dominant contribution to the thermal conductivity. In the static-field approximation, one neglects turbulent motions of field lines, and calculates the diffusion coefficient of thermal electrons ...

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.

CERN Document Server

Antideuterons are among the most promising galactic cosmic ray-related targets for dark matter indirect detection. Currently only upper limits exist on the flux, but the development of new experiments, such as GAPS and AMS-02, provides exciting perspectives for a positive measurement in the near future. In this Paper, we present a novel and updated calculation of both the secondary and primary antideuteron fluxes. We employ a two-zone diffusion model which successfully reproduces cosmic-ray nuclear data and the observed antiproton flux. We review the nuclear and astrophysical uncertainties and provide an up to date secondary (i.e. background) antideuteron flux. The primary (i.e. signal) contribution is calculated for generic WIMPs annihilating in the galactic halo: we explicitly consider and quantify the various sources of uncertainty in the theoretical evaluations. Propagation uncertainties, as is the case of antiprotons, ...

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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.

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 ...

CERN Document Server

In a recent study of a search for enhancements from the galactic center with muons at sea level using the TUPI muon telescope, we have found several ground level enhancements (GLEs) as very sharp peaks above the count rate background. This paper reports a consistent analysis of two GLEs observed in December 2003 and detected after an up-grade of the data acquisition system, which includes a noise filter and which allows us to verify that the GLEs are not mere background fluctuations. The main target of this study is a search for the origin of the GLEs. The results show that one of them has a strong correlation with a solar flare, while the other has an unknown origin, because there is neither a satellite report of a solar flare, nor prompt X-ray emission, and nor a excess of nuclei during the raster scan where the GLE was observed. Even so, two possibilities are analyzed: the solar flare hypothesis and the gamma ray burst (GRB) hypothesis. We ...

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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)

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)

The stability of a symmetric tandem mirror with hot-electron end plugs against low-frequency modes is investigated using a model first proposed by Baldwin. The Baldwin instability, which is due to the coupling of a negative-energy mode in the plug and a shear Alfven mode in the center cell, is confirmed. It is found that this instability is confined to small ranges of value of L/sub c/, the length of the center cell. Under modest restriction of parameters, the unstable regions in L/sub c/ impose little limitation on L/sub c/.

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 ...

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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 ...

International Nuclear Information System (INIS)

This Environmental Assessment (EA) reviews the environmental consequences associated with the proposed action of granting a site use permit to construct and operate a conference center on an approximately 70-acre tract of land on the Savannah River Site (SRS). While the proposed action requires an administrative decision by DOE, this EA reviews the linked action of physically constructing and operating a conference center. The SRS is a DOE-owned nuclear production facility encompassing approximately 200,000 acres in southwestern South Carolina. The proposed conference center would have an area of approximately 4,000 square feet, and would infrequently accommodate as many as 150 people, with the average being about 20 people per day. In addition to the No-Action alternative, under which the Research Foundation would not require the 70-acre tract of SRS land for a conference center, this EA considers site ...

International Nuclear Information System (INIS)

The highest equilibrium free-carrier doping concentration possible in a given material is limited by the ''pinning energy'' which shows a remarkable universal alignment in each class of semiconductors. Our first-principles total energy calculations reveal that equilibrium n -type doping is ultimately limited by the spontaneous formation of close-shell acceptor defects: the 3- -charged cation vacancy in AlN, GaN, InP, and GaAs and the 1- -charged DX center in AlAs, AlP, and GaP. This explains the alignment of the pinning energies and predicts the maximum equilibrium doping levels in different materials. (c) 2000 The American Physical Society

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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)

Safety assessments for clearance of H-beam and valves, main radioactive metal wastes in Kori nuclear power plants, were carried out to derivate a decontamination factor for satisfying the dose limits of clearance level (Maximum individual dose: 10 {mu}Sv/y, collective dose: 1 man{center_dot}Sv/y) in Korea. Maximum individual dose and collective dose were evaluated by internal dose conversion factor which based on the concept of effective dose in ICRP publication 60. The results of maximum individual dose and collective dose is 139 {mu}Sv per year and 0.166 man{center_dot}Sv per year about H-beam, and 158 {mu}Sv per year and 0.468 man{center_dot}Sv per year about valves respectively. Demand decontamination factor satisfied with, which is respectively more than 13.9 and 15.8 for satisfying clearance level.

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Role-limiting approaches support knowledge acquisition (KA) by centering knowledge base construction on common types of tasks or domain-independent problem-solving strategies. Within a particular problem-solving strategy, domain-dependent knowledge plays specific roles. A KA tool then helps a user to fill these roles. Although role-limiting approaches are useful for guiding KA, they are limited because they only support users in filling knowledge roles that have been built in by the designers of the KA system. EXPECT takes a different approach to KA by representing problem-solving knowledge explicitly, and deriving from the current knowledge base the knowledge gaps that must be resolved by the user during KA. This paper contrasts role-limiting approaches and EXPECT`s approach, using the propose-and-revise strategy as an example. EXPECT not only supports users in filling knowledge ...

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The elastic behaviour of YBaCuO specimens has been studied by very low-frequency isothermal internal-friction measurements. A relaxation peak is observed which is attributed to oxygen atom jumps, between A(1/2 0 0) and B(0 1/2 0) sites, in the CuO planes of the orthorhombic phase. A limit relaxation time {tau}{sub 0}, 2.6 {center dot} 10{sup -15}s, and an activation energy, 1.3eV, have been obtained from the shift of the maximum damping frequency observed when the measurement temperature is changed. The proposed values for the limit relaxation time and the activation energy are in good agreement with those previously proposed in the literature.

International Nuclear Information System (INIS)

We derive improved versions of the relations between supermassive black hole mass (M _B_H) and host-galaxy bulge velocity dispersion (#sigma#) and luminosity (L; the M-#sigma# and M-L relations), based on 49 M _B_H measurements and 19 upper limits. Particular attention is paid to recovery of the intrinsic scatter (#epsilon#_0) in both relations. We find log(M _B_H/M _s_u_n) = #alpha# + #beta#log(#sigma#/200 km s"-"1) with (#alpha#, #beta#, #epsilon#_0) = (8.12 #+-# 0.08, 4.24 #+-# 0.41, 0.44 #+-# 0.06) for all galaxies and (#alpha#, #beta#, #epsilon#_0) = (8.23 #+-# 0.08, 3.96 #+-# 0.42, 0.31 #+-# 0.06) for ellipticals. The results for ellipticals are consistent with previous studies, but the intrinsic scatter recovered for spirals is significantly larger. The scatter inferred reinforces the need for its consideration when calculating local black hole mass function based on the M-#sigma# relation, and further implies that there may be substantial selection bias in ...

International Nuclear Information System (INIS)

The authors describe a new method which makes it possible to determine the radial distribution of the diffuse component of galactic gamma rays outside the solar circle. They use the observation that a good correlation exists between gamma-ray intensities and total column densities of the local interstellar gas and that the fractional column density of H_2<0.1 HI outside the solar circle. Thus the gamma-ray intensities are shown to be proportional to N(HI). The authors use the kinematics of the HI to determine the distances from which various fractions of the emission originate in the second and third galactic quadrants. Preliminary results of our analysis show that a significant flux of gamma rays originates from distances as large as 18 kpc from the galactic centre. (Auth.).

CERN Document Server

The study of extragalactic planetary nebulae (EPN) is a rapidly expanding field. The advent of powerful new instrumentation such as the PN spectrograph has led to an avalanche of new EPN discoveries both within and between galaxies. We now have thousands of EPN detections in a heterogeneous selection of nearby galaxies and their local environments, dwarfing the combined galactic detection efforts of the last century. Key scientific motivations driving this rapid growth in EPN research and discovery have been the use of the PNLF as a standard candle, as dynamical tracers of their host galaxies and dark matter and as probes of Galactic evolution. This is coupled with the basic utility of PN as laboratories of nebula physics and the consequent comparison with theory where population differences, abundance variations and star formation history within and between stellar systems informs both stellar and galactic evolution. Here ...

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The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly{alpha} forest, and a radial velocity search for planets around {approx}8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes 5-band imaging of roughly 5200 deg{sup 2} in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg{sup 2}, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and ...

CERN Document Server

Galactic open clusters are since long recognized as one of the best tools for investigating the radial distribution of iron and other metals. We employed FLAMES at VLT to collect UVES spectra of bright giant stars in a large sample of open clusters, spanning a wide range of Galactocentric distances, ages, and metallicities. We present here the results for four clusters: Berkeley 20 and Berkeley 29, the two most distant clusters in the sample; Collinder 261, the oldest and the one with the minimum Galactocentric distance; Melotte 66. Equivalent width analysis was carried out using the spectral code MOOG and Kurucz model atmospheres to derive abundances of Fe, Al, Mg, Si, Ca, Ti, Cr, Ni, Ba; non-LTE Na abundances were derived by direct line-profile fitting. We obtain subsolar metallicities for the two anticenter clusters Be 20 ([Fe/H]=-0.30, rms=0.02) and Be 29 ([Fe/H]=-0.31, rms=0.03), and for Mel 66 ([Fe/H]=-0.33, rms=0.03), located in the third ...

Energy Technology Data Exchange (ETDEWEB)

The second list of objects in the Second Biurakan Spectral Sky Survey of the region centered on alpha 09h50m, delta +55 deg 00 arcmin is given. The list contains data on 110 objects and galaxies of a peculiar physical nature and 24 blue stars. The observations were made with the 40-52 arcsec Schmidt telescope of the Biurakan Astrophysical Observatory with a set of three objective prisms using Kodak IIIaJ and IIIaF emulsions sensitized in nitrogen. The area is found to contain 20 quasar candidates and four Seyfert galaxies, 27 blue stellar objects, 24 galaxies with an appreciable ultraviolet continuum, and 39 emission galaxies without appreciable ultraviolet radiation. The surface brightness of the quasars and Seyferts on the considered area down to the limiting magnitude 19.5 M is more than 1.5 per square degree with allowance for the already known quasars. The surface density of emission galaxies is about four per square degree. 7 references.

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Rhodopseudomonas viridis was grown in liquid culture at 30 degrees C anaerobically in light (generation time, 13 h) and under microaerophilic growth conditions in the dark (generation time, 24 h). The bacterium could be cloned at the same temperature anaerobically in light (1 week) and aerobically in the dark (3 to 4 weeks) if oxygen was limited to 0.1%. Oxygen could not be replaced by dimethyl sulfoxide, potassium nitrate, or sodium nitrite as a terminal electron acceptor. No growth was observed anaerobically in darkness or in the light when air was present. A variety of additional carbon sources were used to supplement the standard succinate medium, but enhanced stationary-phase cell density was observed only with glucose. Conditions for induction of the photosynthetic reaction center upon the change from microaerophilic to phototrophic growth conditions were investigated and optimized for a mutant functionally defective in phototrophic ...

Energy Technology Data Exchange (ETDEWEB)

This report describes the results of EPRI Program S404-28, titled Experimental Modeling of Eddy Current Response'', conducted by the Westinghouse Science and Technology Center (STC). The Westinghouse STC demonstrates that its mercury modeling technique provides an unique bridge between steam generator eddy current field inspection conditions and predictions obtained using recently developed analytical models. The mercury modeling technique was used systematically to explore factors which contribute to primary water stress corrosion cracking (PWSCC) sizing inaccuracy, including probe design, coil excitation frequency, crack length, and crack morphology. Two new proposed techniques for inverting crack lengths from eddy current data are compared with the technique commonly used in field data analysis for PWSCC. The performance of uniform field eddy current probes is compared with the performance of pancake coil probe designs, and an assessment of the ...

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This paper compares two systems providing advanced functions for real-time management of power distribution networks developed in Finland and in France. The overall aim of these systems is to minimize the operational costs (e.g. power losses, outage level, thermal limits). These are to be integrated with a Supervision Control and Data Acquisition system (SCADA) and heterogeneous databases such as network and geographical information systems (AM/FM/GIS). The Finnish system called OPERA has been developed in the past years at the Tampere University of Technology. It is now commercialised by the Versoft Ltd software company and used in 11 control centers. The French system, called AUSTRAL is in the industrialization phase by now at the Research and Development Division of EDF. It will be put into real operation in three distribution utilities in 1997. In this paper, we briefly introduce both systems and discuss their similarities and differences ...

Science.gov (United States)

picture will download the highest resolution version available. In the Center of the Whirlpool Credit: N. Panagia (STScI, ESA), NASA Explanation: In the center of M51, a spiral...

Energy Technology Data Exchange (ETDEWEB)

We conducted broadband absorption measurements of atmospheric water vapor in the ground state, X {sup 1}A{sub 1} (000), from 0.4 to 2.7 THz with a pressure broadening-limited resolution of 6.2 GHz using pulsed, terahertz time-domain spectroscopy (THz-TDS). We measured a total of seventy-two absorption lines and forty-nine lines were identified as H{sub 2}{sup 16}O resonances. All the H{sub 2}{sup 16}O lines identified were confirmed by comparing their center frequencies to experimental values available in the literature.

Energy Technology Data Exchange (ETDEWEB)

A number of epidemiological studies indicate an association between depression and proximity to high voltage transmission lines. These studies have been criticized, however, for using surrogate measures of electromagnetic fields (EMFs) and unstandardized measures of depression. In an effort to overcome these limitations, the Center for Epidemiological Studies Depression (CES-D) scale was administered to 152 women living either adjacent to a transmission line or one block away. Results indicate that homes adjacent to the transmission lines have an average EMF level of 4.86 milligauss at their front door and those one block away have an average of 0.68 milligauss. There was no significant difference in CES-D scores between the groups, controlling for demographic variables. There appeared to be an increase in other health effects, including cancer and miscarriages, but these findings were preliminary and need further investigation.

British Library Electronic Table of Contents (United Kingdom)

In the present study, we report the occurrence of Lyme's borreliosis in patients from the Brazilian Amazon Region. Borreliosis was investigated by immunohistochemistry and focus floating microscopy for Borrelia burgdorferi in skin biopsy samples from 22 patients with both clinical and histopathology evidences compatible with Erythema Migrans. Spirochetes were detected by specific immunohistochemistry and focus floating microscopy for B. burgdorferi in samples from five patients. Clinical cure of the cutaneous lesions was observed in all the patients after treatment with doxycycline regimen as proposed by the Center Disease Control guidelines. A limitation of our study was the fact that we were not able to isolate and culture these organisms. These are the first known Brazilian cases of bor...

Science.gov (United States)

PMID:5017351

International Nuclear Information System (INIS)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during initial annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, the authors have used B doping marker layers in Si to probe the injection of interstitials from near-surface, non-amorphizing Si implants during annealing. The in-diffusion of interstitials is limited by trapping at impurities and has an activation energy of #approx#3.5 eV. Substitutional C is the dominant trapping center with a binding energy of 2--2.5 eV. The high interstitial supersaturation adjacent to the implant damage drives substitutional B into metastable clusters at concentrations below the B solid solubility limit. Transmission electron microscopy shows that the interstitials driving TED are emitted from #left brace#311#right brace# defect clusters in the damage region at a rate which also exhibits an ...

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 ...

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Diffuse {gamma}-ray emission produced by the interaction of cosmic-ray particles with matter and radiation in the Galaxy can be used to probe the distribution of cosmic rays and their sources in different regions of the Galaxy. With its large field of view and long observation time, the Milagro Gamma Ray Observatory is an ideal instrument for surveying large regions of the Northern Hemisphere sky and for detecting diffuse {gamma}-ray emission at very high energies. Here, the spatial distribution and the flux of the diffuse {gamma}-ray emission in the TeV energy range with a median energy of 15 TeV for Galactic longitudes between 30{sup o} and 110{sup o} and between 136{sup o} and 216{sup o} and for Galactic latitudes between -10{sup o} and 10{sup o} are determined. The measured fluxes are consistent with predictions of the GALPROP model everywhere except for the Cygnus region (l {element_of} [65{sup o}, 85{sup o}]). For the Cygnus region, the ...

Science.gov (United States)

Energetic ions interact with materials by collisions with the nuclei and electrons of the atoms that make up the material. In these collisions energy and momentum is transferred from the projectile particle which is a moving atom or ion, to the target particles (atomic nucleus or electron). Each collision leads to a slowing down of the moving projectile and also a deflection of the trajectory which gives rise to the term scattering which is often used synonymously to describe the energy transfer process. In this chapter, we introduce from an experimental viewpoint the underlying theory for interaction of ions for analysis and modification of nanometer scale materials. A more detailed theoretical overview of the topic can be found in the recent monographs by Sigmund. Detailed derivations of the formulae introduced will not be given here but can be found in standard texts that are indicated by references. The treatment here starts by considering an individual scattering event. The ...

International Nuclear Information System (INIS)

Nuclear reaction rates and opacity are important parameters in stellar evolution. The input physics in a stellar evolution code determines the main theoretical characteristics of the stellar structure, evolution and nucleosynthesis of a star. For different input physics, in this work we calculate stellar evolution models of very massive first stars during the hydrogen and helium burning phases. We have considered 100 and 200M_sun galactic and pregalactic stars with metallicity Z = 10"-"6 and 10"9, respectively. The results show important differences from old to new formulations for the opacity and nuclear reaction rates, in particular the evolutionary tracks are significantly affected, that indicates the importance of using up to date and reliable input physics. The triple alpha reaction activates sooner for pregalactic than for galactic stars.

International Nuclear Information System (INIS)

New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sersic log I #propor to# r "1"/"n functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Two kinds of departures are seen at small radii. All 10 of our ellipticals with total absolute magnitudes M_V_T #<=# -21.66 have cuspy cores-"missing light"-at small radii. Cores are well known and naturally scoured by binary black holes (BHs) formed in dissipationless ("dry") mergers. All 17 ellipticals with -21.54 #<=# M_V_T #<=# -15.53 do not have cores. We find a new distinct component in these galaxies: all coreless ellipticals in our sample have ...

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 \

Energy Technology Data Exchange (ETDEWEB)

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)

Science.gov (United States)

... Programmatic Terms and Conditions for the Materials Research Science and Engineering Centers (MRSEC ... NSF Grants Officer. 2. Program Description: Materials Research Science and Engineering Centers ...

International Nuclear Information System (INIS)

We present an abundance analysis based on high-resolution spectra of 10 stars selected to span the full range in metallicity in the Ursa Minor (UMi) dwarf spheroidal (dSph) galaxy. We find that [Fe/H] for the sample stars ranges from -1.35 to -3.10 dex. Combining our sample with previously published work for a total of 16 luminous UMi giants, we establish the trends of abundance ratios [X/Fe] as functions of [Fe/H] for 15 elements. In key cases, particularly for the #alpha#-elements, these trends resemble those for stars in the outer part of the Galactic halo, especially at the lowest metallicities probed. The neutron-capture elements show an r-process distribution over the full range of Fe metallicity reached in this dSph galaxy. This suggests that the duration of star formation in the UMi dSph was shorter than in other dSph galaxies. The derived ages for a larger sample of UMi stars with more uncertain metallicities also suggest a population dominated by ...

Science.gov (United States)

Research Center last approximately 1.5 hours and include stops at the Space Weather Prediction Center, ESRL Global Monitoring Division for information on the carbon dioxide...

Science.gov (United States)

Abstract: Inertial navigation error analysis of space vehicle during reentry. NASA Center: Ames Research Center Publication Year: 1963 ...

UK PubMed Central (United Kingdom)

ObjectiveFamily-centered bedside rounds (FCBR) are recommended to improve trainee education, patient outcomes, and family satisfaction. However, bedside teaching...Full Text Available

Science.gov (United States)

The Global Warming International Center (GWIC) is the international body disseminating information on global warming science and policy, serving both governamental, non-governamental ... ...

Wastenet

Pages 184-197: Understanding Personal Change in a Women’s Faith-Based Transitional Center/title link ...titleUnderstanding Personal Change in a Women’s Faith-Based Transitional Center/dc:title

International Nuclear Information System (INIS)

A visual study of film boiling using photographic and high speed motion-picture methods was carried out to determine the flow regime transition criteria in the post-CHF region. An idealized inverted annular flow was obtained by introducing a liquid jet of Freon 113 through a nozzle, precisely centered with respect to the internal diameter of the test section, with an annular gas flow. The respective ranges for liquid and gas exit velocities were 0.05 to 0.5 and 0.03 to 7.9 m/s. Nitrogen and helium were used in the study. For the present configuration, there are four basic flow regimes. Beginning from the nozzle exit, there is a smooth, inverted annular flow section with liquid in the core and gas in the annulus; followed by the rough wavy section with an intact liquid core, the agitated and the dispersed flow regimes. For a given liquid jet velocity, the axial extent of each flow regime decreases with increasing gas velocity through the annulus. Generalized ...

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The e{sup +}e{sup -}{yields}pp cross section is determined over a range of pp masses, from threshold to 4.5 GeV/c{sup 2}, by studying the e{sup +}e{sup -}{yields}pp{gamma} process. The data set corresponds to an integrated luminosity of 232 fb{sup -1}, collected with the BABAR detector at the PEP-II storage ring, at an e{sup +}e{sup -} center-of-mass energy of 10.6 GeV. The mass dependence of the ratio of electric and magnetic form factors, G{sub E}/G{sub M}, is measured for pp masses below 3 GeV/c{sup 2}; its value is found to be significantly larger than 1 for masses up to 2.2 GeV/c{sup 2}. We also measure J/{psi}{yields}pp and {psi}(2S){yields}pp branching fractions and set an upper limit on Y(4260){yields}pp production and decay.

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Concerning the above, it is discussed whether such a system is feasible in Japan. A zinc/air cell system requires some special plants for zinc regeneration, etc. It is necessary to build a zinc refining plant and to install dozens of electrode replacing facilities in an area dozens of kilometers in diameter with the plant at the center. For such a system to be functional, there have to be several tens of thousands of automobile users in a limited area. In Japan, so large a number will not be found anywhere even if the appeal is directed to those in the postal service and electric utilities. There will be no economic success in Japan, different from in Germany. As for the economic comparison between a zinc/air cell system and natural gas system, the two will be equivalent to each other as far as the use of the quick filling stations for the natural gas automobiles remains as it is. When the number in consideration is so large as several tens of ...

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The NPDGamma Experiment measures the parity-violating correlation A{sub {Gamma}Y} between neutron spin and photon momentum in the reaction {rvec n} + p {yields} d + {gamma}. Knowledge of A{sub {Gamma}Y} and other parity-violating observables in few-body nuclear systems will provide constraints for a parameterized description of {Delta}S = 0 parity-violating phenomena free from complications of nuclear structure. The NPDGamma experiment uses a polarized cold pulsed neutron beam, a liquid parahydrogen target, and a cylindrical array of 48 CsI(Tl) scintillation detectors operated in current mode to search for the asymmetry. NPDGamma recently completed the first phase of the program to measure A{sub {Gamma}Y} at the Los Alamos Neutron Science Center with the preliminary result A{sub {Gamma}Y} = (-1.2 {+-} 2.1(stat.) {+-} 0.1(sys.)) x 10{sup -7}, reproducing the previous upper limit from a measurement at a reactor facility. We discuss the ...

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The key to improving transmission-network security is faster response to contingencies. Now a new breed of pumped-storage plant - designed for ultra-fast response - may soon provide a tool dispatchers can use to improve network security. This type of plant can also substantially increase the effective capacity of existing transmission lines and improve the performance of thermal generating units. The Mt. Hope Waterpower Project, planned for Rockaway Township, NJ, 35 miles west of New York City, lies strategically adjacent to major load centers at the eastern end of the PJM control area and near the interconnection point with the New York Power Pool (NYPP). This location also is in an area deficient in significant generating facilities. Maximum design capacity of the project is 2000 MW, provided by six reversible pump/turbines, each with a nominal 340-MW rating. The upper reservoir, with a surface area of only 60 acres, provides 5000 acre-ft of active storage volume ...

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The Evaluated Nuclear Data File (ENDF) formats and libraries are decided by the Cross Section Evaluation Working Group (CSEWG), a cooperative effort of national laboratories, industry, and universities in the U.S. and Canada, and are maintained by the National Nuclear Data Center (NNDC). Earlier versions of the ENDF format provided representations for neutron cross sections and distributions, photon production from neutron reactions, a limited amount of charged-particle production from neutron reactions, photo-atomic interaction data, thermal neutron scattering data, and radionuclide production and decay data (including fission products). Version 6 (ENDF-6) allows higher incident energies, adds more complete descriptions of the distributions of emitted particles, and provides for incident charged particles and photonuclear data by partitioning the ENDF library into sub-libraries. Decay data, fission product yield data, thermal scattering data, ...

CERN Document Server

We consider a class of nonlinear Schrodinger / Gross-Pitaevskii (NLS/GP) equations with periodic potentials, having an even symmetry. We construct "solitons", centered about any point of symmetry of the potential. For focusing (attractive) nonlinearities, these solutions bifurcate from the zero state at the lowest band edge frequency, into the semi-infinite spectral gap. Our results extend to bifurcations into finite spectral gaps, for focusing or defocusing (repulsive) nonlinearities under more restrictive hypotheses. Soliton nonlinear bound states with frequencies near a band edge are well-approximated by a slowly decaying solution of a homogenized NLS/GP equation, with constant homogenized effective mass tensor and effective nonlinear coupling coefficient, modulated by a Bloch state. For the critical NLS equation with a periodic potential, e.g. the cubic two dimensional NLS/GP with a periodic potential, our results imply that the limiting ...

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Mixed-conducting ceramic oxides have potential uses in high-temperature electrochemical applications such as solid oxide fuel cells, advanced batteries, sensors, and oxygen-permeable membranes. The Sr-Fe-Co-O system combines high electronic/ionic conductivity with appreciable oxygen permeability at elevated temperatures. Dense ceramic membranes made of this material can be used to separate high-purity oxygen from air without the need for external electrical circuitry, or to partially oxidize methane to produce syngas. Samples of Sr{sub 2}Fe{sub 3{minus}x}Co{sub x}O{sub y} (with x = 0, 0.6, 1.0, and 1.4) were prepared by solid-state reaction in atmospheres with various oxygen partial pressures (pO{sub 2}) and were characterized by X-ray diffraction, scanning electron microscopy, and electrical conductivity measurements. Phase components of the samples are dependent on cobalt concentration and synthesis pO{sub 2}. Total conductivity increases with increasing temperature and cobalt ...

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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NASA's Ames Research Center awarded Ciencia, Inc., a Small Business Innovation Research contract to

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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The data center in this study had a total floor area of 8,580 square feet (ft{sup 2}) with one-foot raised-floors. It was a rack lab with 440 racks, and was located in a 208,240 ft{sup 2} multi-story office building in San Jose, California. Since the data center was used only for testing equipment, it was not configured as a critical facility in terms of electrical and cooling supply. It did not have a dedicated chiller system but served by the main building chiller plant and make-up air system. Additionally, it was served by a single electrical supply with no provision for backup power. The data center operated on a 24 hour per day, year-round cycle, and users had all hour full access to the data center facility. The study found that data center computer load accounted for 23% of the overall building electrical load, while the total power consumption attributable to the data ...

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Using the infrared spectroscopy method, we have studied the effect of thermal dehydration (under vacuum and in air) and treatment with water vapor on the acid centers of very high silicon zeolites of the ZSM type. We have shown that dehydration under vacuum and in air completely and irreversibly removes the OH groups at 1120/sup 0/K, while treatment with water vapor removes these groups at 770/sup 0/K. The Lewis acid centers of dehydrated zeolites (represented by two types of centers) are more heat-stable than the Bronsted acid centers, but the vapor treatment at 1020/sup 0/K leads to the disappearance of the Lewis acid centers. In this work, we discuss the reasons for destruction of the acid centers of the zeolites under different treatment conditions.

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Two branches of research are conducted in this thesis. The first deals with nonlinear combustion response as a mechanism for triggering combustion instabilities in solid rocket motors. A nonlinear wave equation is developed to study a wide class of combustion response functions to second-order in fluctuation amplitude. Conditions for triggering are derived from analysis of limit cycles, and regions of triggering are found in parametric space. Introduction of linear cross-coupling and quadratic self-coupling among the acoustic modes appears to be how the nonlinear combustion response produces triggering to a stable limit cycle. Regions of initial conditions corresponding to stable pulses were found, suggesting that stability depends on initial phase angle and harmonic content, as well as the composite amplitude, of the pulse. Also, dependence of nonlinear stability upon system parameters is considered. The second part of this thesis presents ...

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The hydration behavior of a number of square planar Pt(II) bis(cyano) complexes has been examined, and the limiting stoichiometries are related to the steric requirements of the dinitrogen bidentate ligands coordinated to the metal center. In particular, the IR, UV/vis, and [sup 1]H, [sup 13]C, and [sup 195]Pt NMR spectroscopic data for the compound Pt[sup II]dtbipy(CN)[sub 2] [dtbipy = 4,4[prime]-[l brace]C(CH[sub 3])[sub 3][r brace][sub 2]-2,2[prime]-bpy] have been determined and show that, at relative humidities (rh) above [approximately]40%, this complex sorbs five water molecules at room temperature. The sorption process consists of a rapid step in which one H[sub 2]O adds to the complex and which appears to be independent of rh, followed by a slower, rh-dependent step leading to the final stoichiometry. In contrast, the analogous 2,2[prime]-bpy complex sorbs no water under these conditions, while the 4,4[prime]-(CH[sub 3])[sub ...

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 ...

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

We review X-ray plasma diagnostics based on the line ratios of He-like ions. Triplet/singlet line intensities can be used to determine electronic temperature and density, and were first developed for the study of the solar corona. Since the launches of the X-ray satellites Chandra and XMM-Newton, these diagnostics have been extended and used (from CV to Si XIII) for a wide variety of astrophysical plasmas such as stellar coronae, supernova remnants, solar system objects, active galactic nuclei, and X-ray binaries. Moreover, the intensities of He-like ions can be used to determine the ionization process(es) at work, as well as the distance between the X-ray plasma and the UV emission source for example in hot stars. In the near future thanks to the next generation of X-ray satellites (e.g., Astro-H and IXO), higher-Z He-like lines (e.g., iron) will be resolved, allowing plasmas with higher temperatures and densities to be probed. Moreover, the so-called satellite ...

CERN Document Server

This paper constructs an analytic framework for calculating the assembly of galactic disks from the collapse of gas within dark matter halos, with the goal of determining the surface density profiles. Gas parcels (baryons) fall through the potentials of dark matter halos on nearly ballistic, zero energy orbits and collect in a rotating disk. The dark matter halos have a nearly universal form, as determined previously through numerical simulations. The calculation is first carried out for a variety of pre-collapse mass distributions and rotation profiles, including polytropic spheres in hydrostatic equilibrium with the halo potential. The resulting disk surface density profiles have nearly power-law forms, with well-defined edges. This idealized scenario is generalized to include non-spherical starting states and multiple accretion events (due to gas being added to the halo via merger events). This latter complication is explored in detail and considers a log-normal ...

CERN Document Server

The energy fed by active galactic nuclei to the surrounding diffuse baryons changes the latter's amount, temperature, and distribution; so in groups and in member galaxies it affects the X-ray luminosity and also the Sunyaev-Zel'dovich effect. Here we compute how the latter is enhanced by the transient blastwave driven by a shining quasar, and is depressed when the equilibrium is recovered with a depleted density. We constrain such depressions and enhancements with the masses of relic black holes in galaxies and the X-ray luminosities in groups. We discuss how all these linked observables can tell the quasar contribution to the thermal history of the baryons pervading galaxies and groups.

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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 ...

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The University of North Carolina Comprehensive Pain Center, which has been in existence since 1972, is a pain evaluation, treatment and research program based upon individual diagnosis, comprehensive...Full Text Available

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The National Nuclear Data Center provides information on nuclear reactions, nuclear structure, and decay data, and is a part of the Nuclear Data Center Network, established to coordinate the compilation and dissemination of nuclear data on an international scale.

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... materials science and education beyond what is expected from any one Center. "Advanced materials are ... for DMR's Division of Materials Research. "Fundamental research on materials is essential to the ...

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Jul 5, 2007 ... Search Criteria: Search Field: All > Results : All > Search Term: (Manganese 63) [x]. Sort results by: NASA Center | Date Added to NTRS ...

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Features: CHUQUICAMATA, LARGE OPEN PIT MINING OPERATIONS, ROADS, HILLS Center Point Latitude: -22.3 Center Point Longitude: -68.9 (Negative numbers indicate ...

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The concept of "one-stop information shopping" is becoming a reality at Columbia-Presbyterian Medical Center. Our goal is to provide access from a single workstation to clinical, research, and library...Full Text Available

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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... Institute of Plasma Physics of the National Science Center 'Kharkov Institute

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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CONTINENT > EUROPE > EASTERN EUROPE > CZECH REPUBLIC .... CIESIN > Industry and Energy > Energy Production > Nuclear Energy ...

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... University of Maryland. Participants Doris Ash Chabot Observatory & Science Center Krishna Athreya ...

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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Oct 23, 2007 ... Global Tropospheric Experiment (GTE) PEM West A Flights.

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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... Page 43. Integrated Audio Technology Demonstrator The Integrated Audio Technology Dem- development for this application is successful. ...

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This report describes work performed by MTC Technologies (MTCT) for NASA Glenn Research Center (GRC)

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The data center in this study had a total floor area of 3,024 square feet (ft{sup 2}) with one-foot raised-floors. It was a rack lab with 147 racks, and was located in a 96,000 ft{sup 2} multi-story office building in San Jose, California. Since the data center was used only for testing equipment, it was not configured as a critical facility in terms of electrical and cooling supply. It did not have a dedicated chiller system but was served by the main building chiller plant and make-up air system. Additionally it was served by only a single electrical supply with no provision for backup power in the event of a power outage. The Data Center operated on a 24 hour per day, year-round cycle, and users had full-hour access to the data center facility. The study found that data center computer load accounted for 15% of the overall building electrical load, while the total power ...

International Nuclear Information System (INIS)

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

International Nuclear Information System (INIS)

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

Science.gov (United States)

Jun 19, 2008 ... As a result of the May 30 police chase on Redstone Arsenal, ..... Brian Mitchell , the Marshall Center's education and public ...

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The high energy limit of Quantum Chromodynamics is one of the most fascinating areas in the theory of strong interactions. Over a decade ago the HERA experiment at DESY in Hamburg provided strong evidence for the rise of the proton structure function at small values of the Bjorken variable x. This behavior can be explained as an increase of the gluon density of the proton with energy or correspondingly with smaller values of x. This increase can be attributed on the other hand to the large probability of gluon splitting in QCD. The natural framework for describing the gluon dynamics at small x is the Balitskii-Fadin-Kuraev-Lipatov formalism developed some 30 years ago. It predicts that the gluon density grows very fast with increasing energy, as a power with a large intercept. This increase has to be tamed in order to satisfy the unitarily bound. Over two decades ago, Gribov, Levin and Ryskin proposed the mechanism called the parton saturation, which slows down the ...

UK PubMed Central (United Kingdom)

We investigated nutrient limitations during hydrocarbon degradation in a sandy soil and found that fixed nitrogen was initially a limiting nutrient but that N limitation could sometimes be overcome...Full Text Available

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A sodium-water reaction drove from the single tube break in steam generator of FBR might overheat labor tubes rapidly under internal pressure loadings. If the temperature of tube wall becomes too high, it has to be evaluated that the stress of tube does not exceed the material strength limit to prevent the propagation of tube rupture. This study clarified the tensile and creep properties of Mod.9Cr-1Mo steel at ultra-high temperature which will be used in evaluation of the tube burst by sodium-water reaction. The strain rates for tensile test are from 10%/min to 10%/sec, and creep-rupture time is maximum 277sec. The range of test temperature is 700degC to 1300degC. The main results obtained were as follows; (1) The evaluation data on the relationship between tensile strength and strain rate and creep-rupture strength in shorter time on Mod.9Cr-1Mo steel were acquired. (2) Short-term mechanical properties of Mod.9Cr-1Mo steel were evaluated based on the results of ...

Science.gov (United States)

Over the recent years the nuclear structure around the N = 50 shell closure, which is very pronounced in the strontium and zirconium isotopes, has been the subject of extensive experimental and theoretical work. On the proton side Z = 38 and Z = 40 provide fairly closed sub-shells. In the strontium isotopes the lg/sub 9/2/ neutron shell is closed at /sup 88/Sr, supplying relatively pure neutron-hole and neutron-particle states with large spectroscopic factors in /sup 87/Sr and /sup 89/Sr, as well as core-coupled states. The mass region is thus ideally suited to examine the transition from a correlated to an uncorrelated (chaotic.) excitational behavior. These two types are characterized e.g. by the density of excited states, the transition strengths, and the spectroscopic factors observed in transfer reactions. We conducted (n,..gamma..) and (d,p) reactions leading to /sup 87,88,89/Sr in addition to /sup 88/Sr(d,t)/sup 87/Sr and 24 keV neutron capture in /sup 88/Sr. The vast amounts of ...

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The present thesis presents two different aspects of my work in the L3 experiment, which are on one side the search for supersymmetric particles, the scalar leptons, in two different topologies 'electron + X + E' and '2 leptons + 2 photons + E', each of them being related to two theoretical SUSY models, m-SUGRA and GMSB. On the other side my work has been completed by the study of the BGO crystal electromagnetic calorimeter of L3, and the calibration of the electromagnetic calorimeter EGAP. After the essential motivations being reviewed, the production and disintegration modes are detailed concerning the scalar lepton sector at LEP. Then one presents the analysis techniques which I used to perform my selection, and also the results obtained from the data collected by L3 for center of mass energies between {radical} S =183 GeV and 202 GeV. The selection criteria that allow to isolate the events I looked for, including efficiencies ...

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Thermoplastic encapsulation has been extensively studied at Brookhaven National Laboratory`s (BNL) Environmental and Waste Technology Center (EWTC) as a waste encapsulation technology applicable to a wide range of waste types including radioactive, hazardous and mixed wastes. Encapsulation involves processing thermoplastic and waste materials into a waste form product by heating and mixing both materials into a homogeneous molten mixture. Cooling of the melt results in a solid monolithic waste form in which contaminants have been completely surrounded by a polymer matrix. Heating and mixing requirements for successful waste encapsulation can be met using proven technologies available in various types of commercial equipment. Processing techniques for thermoplastic materials, such as low density polyethylene (LDPE), are well established within the plastics industry. The majority of commercial polymer processing is accomplished using extruders, mixers or a ...

International Nuclear Information System (INIS)

The paper generalizes some results of the United States/Moldova program on advanced composite organic and semiconductor light emitters. High density exciton system bound to N impurity superlattice grown by modern technologies and GaP:N, GaP:N:Sm nanocrystals distributed in transparent fluorine-containing polymers will be used as the base elements for new generation of optoelectronic devices. The work seeks to expand further the applications of GaP itself through the formation of nanocomposites. Classic and new methods are applied for preparation of GaP:N nanoparticles with the controlled dimensions developed clear quantum confinement effect. The long-term ordered bulk GaP crystals as well as their nanoparticles have been investigated by TEM, XRD, Raman scattering, and luminescent methods. The evolution of the Raman Light Scattering and luminescence spectra is reported from pure and doped GaP single crystals grown over 40 years ago and evaluated approximately every 15 years. For the ...

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The reactions of CF{sub 3}O radicals with (1) NO and (2) NO{sub 2} were studied using two different experimental techniques. A laser photolysis/LIF detection method was applied for measuring the rate constants as a function of temperature (T=222-302 K) and total pressure (p{sub tot}=7-107 mbar). Whereas the reaction with (1) NO was found to be independent of temperature and pressure with k{sub 1}=(4.5{+-}1.2) x 10{sup -11} cm{sup 3}s{sup -1}, the reaction with (2) NO{sub 2} was found to be dependent on both of these variables. The temperature dependence of k{sub 2} in the high pressure limit can be given by the expression k{sub 2{infinity}}{sup -}(T)=(8{+-}5) x 10{sup -13} exp ((863{+-}194) K/T) cm{sup 3}s{sup -1}. The product distributions of the two reactions were determined in separate experiments using steady-state photolysis combined with FTIR spectroscopy. For reaction (1) only CF{sub 2}O was found as a reaction product with a yield of 0.93{+-}0.10, ...

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This paper details the development of a decontamination approach for the West Valley Demonstration Project (WVDP), Decontamination Project Plan (Plan). The WVDP is operated by West Valley Nuclear Services Company (WVNSCO), a subsidiary of Westinghouse Government and Environmental Services, and its parent companies Washington Group International and British Nuclear Fuels Limited (BNFL). The WVDP is a waste management effort being conducted by the United States Department of Energy (DOE) at the site of the only commercial nuclear fuel reprocessing facility to have operated in the United States. This facility is part of the Western New York Nuclear Service Center (WNYNSC), which is owned by the New York State Energy Research and Development Authority (NYSERDA). As authorized by Congress in 1980 through the West Valley Demonstration Project Act (WVDP Act, Public Law 96-368), the DOE's primary mission at the WVDP is to solidify high-level ...

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CERN Document Server

We report the results of the evaluation of the ``concentration-density'' relation of galaxies in the local universe, taking advantage of the very large and homogeneous data set available from the Las Campanas Redshift Survey (Shectman et al. 1996). This data set consists of galaxies inhabiting the entire range of galactic environments, from the sparsest field to the densest clusters, thus allowing us to study environmental variations without combining multiple data sets with inhomogeneous characteristics. Concentration is quantified by the automatically-measured concentration index $C$, which is a good measure of a galaxy's bulge-to-disk ratio. The environment of the sample galaxies is characterized both by the three-space local galaxy density and by membership in groups and clusters. We find that the distribution of C in galaxy populations varies both with local density and with cluster/group membership: the fraction of centrally-concentrated galaxies increases ...

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, ...

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.

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...

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. ...

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Electric utilities are actively seeking ways of optimizing the economics of their operations by improving productivity and reducing time and money spent on maintenance. Iberdrola, a Spanish utility, is using advanced machine condition-monitoring technology to centralize control and maintenance of its hydropower projects as a means of achieving those goals. The company is using a blend of technologies to supervise their projects from a regional control center. The monitoring scheme makes use of data from on-line, machine-condition monitors, displays from in-plant audio asnd video equipment, and analysis from the control center`s SCADA system.

Science.gov (United States)

This paper obtains the acidity spectra of modernites and SVK-zeolites from the heats of adsorption of NH/sub 3/ at 300 C and compares the catalytic activity of these zeolites with the cracking of n-octane and the isomerization of o-xylene. It is shown that the calculation of the specific catalytic activity of centers of different strengths by the method of regional rates allows one to predict the activity of the zeolites from the acidity spectra. It follows from the calculation that only the centers of Bronsted acidity are active towards cracking but that the centers of Lewis acidity are also active towards isomerization.

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Earlier studies had concluded that the preferred direction of the rocket nozzle should ..... Center had to redesign the sensor canisters, brackets and cable supports. ... depending on inspection of the quality of the incoming pictures in real-time. ...

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... Multi-robot Operator Control ... Way-point navigation (UUV performing lawn-mower ... Funded by JIEDDO to improve operation of EOD robots ...

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The results of this research centered on the experimental studies of a single superconducting persistent current qubit, the implementation of type-II algorithms using these qubits, and the proposal for adiabatic quantum computing using these qubits. The m...

International Nuclear Information System (INIS)

Lead is known to enter substitutionally in divalent state when doped in alkali halides. When irradiated at room temperature these lead centers (Pb"+"+) act as traps for electrons knocked off from the halogen ions and become Pb"+ and Pb"0 (for large doses of irradiation). These changes could be followed in the optical absorption studies. These lead-doped crystals after X-ray irradiation yield a thermoluminescence output smaller than that observed in 'pure' crystals. However, two new glow peaks are observed in additions to those due to F-centers. In KCl : Pb and Kbr : Pb crystals part of the F-center glow preceds the new glow peaks. The new peaks are attributed to the Pb"+ and Pb"0 centers. The glow peak temperatures and trap depths for these peaks an obtained by total-curve fitting method are reported. (author).

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... Astronomy & Space Biology Chemistry & Materials Computing Earth & Environment Education ... Materials Research Center at the University of Chicago, one of nearly 30 NSF-supported Materials ...

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Education resources dealing with solar-terrestrial physics, solar effects, solar radiation, etc. Includes links to short reference papers on subjects ... ...

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ROBOT-ASSISTED RADICAL LAPAROSCOPIC PROSTATECTOMY WAKE FOREST UNIVERSITY BAPTIST MEDICAL CENTER WINSTON-SALEM, NC 00:00:08 ANTHONY ATALA, MD: I would like ...

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This paper summarizes the main features of four current REDD proposals: Compensated Reduction, Papua New Guinea et al; Joint Research Center; and Brazil. ... ...

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Sep 12, 1975 ... POCKET CALCULATORS. Jose P. Olivares 35, Robert B. Clowns and ... of pocket calculators and has an- Washington to arrive by Nov. 20. ...

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... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

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... 9 SIMPLIFICATION STUDY RECOMMENDATIONS - MIL-STD-2073-1/2 ... SIMPLIFICATION STUDY RECOMMENDATIONS - MIL-STD-2073-1/2 ...

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Data on French nuclear electricity generation sites, nuclear power plant operations personnel, operation simulators, nuclear training centers and training statistics are presented.

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Like few other organs, the skin is continuously exposed to multiple exogenous and endogenous stressors. Superimposed on this is the impact of psychological stress on skin physiology and pathology....Full Text Available

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and the Wildland Firefighter Foundation. To request a marker click here. Engraved bricks may also be purchased from the Foundation to become part of the site. To request a...

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Co-op students hired since December 3, 1983 will be covered under FERS. ... amount of sick leave that can be accumulated for use in succeeding years. 11. ...

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A waterjet coating-removal system was developed at NASA's Marshall Space Flight Center in Huntsville, Ala., to remove thermal protective coatings from the ...

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NASA Nebula in Action: Cloud Computing Case Examples. James Williams, NASA Ames Research Center, james.f.williams@nasa.gov. Abstract In 2009 ...

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Aug 21, 2003 ... Her research interests have included hot stars, colliding stellar winds, binary star evolution and evolved stellar companions. ...

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star formation. To either side of the center, a small bar of dust and gas is helping to fuel the new stars. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the...

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The Bantam System Technology Project is one element of the Advanced Space Transportation Program -- a NASA initiative to reduce the cost of space launch and ...

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... established in allied communications publications (ACP); DISA circulars (DISAC), Joint Army-Navy-Air Force publications (JANAP), and MAJ- COM ...

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Liquid nitrogen dewar loading at Kennedy Space Center for STS-71 flight with Stan Koszelak (right),

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the Missionaries and Cannibals, Fool's Disk, the Blocks World. and the 8-Puzzle. Also ...... place the sets of missionaries and cannibals by ob- ...

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... of China Lake Naval Weapons Center, California. ... Figure 4: The Space-Based Laser cleaning ... of Aeronautics and Astronautics (AIAA) Space 2001 ...

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A new supersymmetric gauge-invariant model is proposed. It is shown that the hidden-symmetry algebra for this model is the Kac-Moody algebra without a center.

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indicate incipient flow separation. The peak stagnation line ...... culations of Transonic Fan Performance, AGARD Propul- sion and Energetics Symposium on ...

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... Institute of Plasma Physics, National Science Center 'Kharkov Institute of

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and audio technology. The exhibition will travel to muse- ums and science centers in several U.S. cities over the next 5 years. Back in the classroom, ...

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(1976). USSR Lupin, VM Ramazanov, PE Tomskij Gosudarstvennyj Univ.

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Jun 25, 1982 ... stove cooktop, great for camp or cot- ment for rent by day, week or month. $4, 000 neg. Call Mike, 483-4231 ...

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diet and genetic obesity metabolic defects and inflammation. To determine the role of adipocyte death in promoting adipose tissue inflammation and insulin resistance in animal...

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CESAREAN SECTION SHAWNEE MISSION MEDICAL CENTER MERRIAM, KANSAS March 13, 2008 00:00:09 ANNOUNCER: Tonight you will experience the miracle of birth during ...

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evaluation, novelty detection, resource discovery, interfaces and visualization, digital libraries, computational social science, and cross-lingual information retrieval. The CIIR...

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... a Networked Embedded Sensing Toolkit (MSR Sense ... edging due to mis-registration than the ... Langrebe, Signal theory in multisensor remote sensing ...

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respectively. This is a NASA and GSFC requirement to help ensure our computer and network security on center. In the near future, ftp access, with the exception of anonymous ftp of...

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Aug 6, 2009 ... be cleaned with common household disinfectants regularly and after increased crowd contact. Marshall's Emergency Operations Center and the ...

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The NASA Langley Distributed Active Archive Center archives and distributes data relating to Radiation Budget, Clouds, Aerosols, and Troposheric Chemistry.

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credited for unused sick leave when they retire.) The FERS Sick Leave Credit would provide the exact same benefit to FERS ...

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We advance a tentative composite model for computer security at JPL, together with inter and intra networking with other NASA centers and overseas clients.

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inhi bi Led ethylene glycol-water solutions for Apol lo spacecraft en- vironmental control systems (I), the concentration of sodium sulfi te ...

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The quasi-static normal indentation of sandwich panels with quasi-isotropic laminated composite skins and honeycomb or foam cores, by spherical indentors, has been investigated using experiments and finite element analysis. The experimental program emphasized the effects of indentor size on the resulting load indentation responses, failure mechanisms in the skin and the core, and the measurement of contact areas between indentor and the target. The sandwich panels were indented up to the initiation of skin fracture and the resulting contact data was used to characterize contact power laws. A non-linear finite element model was developed based on the experimental observations to systematically explore the indentation behavior of diverse sandwich configurations and to investigate the contact pressure distributions. The finite element model was used as an experimental tool in the development of a simple non-dimensional semi-empirical model that was based on the Graeco-Latin-square ...

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A unified Nonhydrostatic Multiscale Model on the Arakawa B grid (NMMB) designed for a broad range of spatial and temporal scales has been under development within the Earth System Modeling Framework (ESMF) at the National Centers for Environmental Prediction (NCEP) as a part of the new National Environmental Modeling System (NEMS). The model follows the general modeling philosophy of the NCEP's WRF NMM grid-point regional dynamical core. The model uses the regular latitude-longitude grid for the global domain, and a rotated latitude-longitude grid in regional applications. The nonhydrostatic component of the model dynamics is introduced through an add-on module that can be turned on or off depending on resolution. The "isotropic" quadratic conservative finite-volume horizontal differencing employed in the model conserves a variety of basic and derived dynamical and quadratic quantities and preserves some important properties of differential operators. Among these, ...

Energy Technology Data Exchange (ETDEWEB)

California utilities have been exploring the use of critical peak prices (CPP) to help reduce needle peaks in customer end-use loads. CPP is a form of price-responsive demand response (DR). Recent experience has shown that customers have limited knowledge of how to operate their facilities in order to reduce their electricity costs under CPP (Quantum 2004). While the lack of knowledge about how to develop and implement DR control strategies is a barrier to participation in DR programs like CPP, another barrier is the lack of automation of DR systems. During 2003 and 2004, the PIER Demand Response Research Center (DRRC) conducted a series of tests of fully automated electric demand response (Auto-DR) at 18 facilities. Overall, the average of the site-specific average coincident demand reductions was 8% from a variety of building types and facilities. Many electricity customers have suggested that automation will help them institutionalize their ...

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The performance of a gas-fuelled diesel engine (dual fuel) is examined at light load and an effective threshold limit to the combustion of the gaseous fuel through bulk flame spread is identified. The relationship of such a limit to some of the key operating parameters is then discussed. A comparison between the measured values of the limit with those corresponding to the lower flammability limits of the gaseous fuel when evaluated under the prevailing cylinder conditions during pilot diesel fuel ignition showed similar trends. It is suggested that such a similarity may form a basis for estimating the lean operation limits for duel a fuel combustion in engines. A simple approach for estimating the limiting equivalence ratio for the apparent bulk flame spread limit is described for a methane-fuelled dual fuel engine. (Author)

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Digital libraries continue to flourish. At the same time, the principles of user-centered design and the practice of usability testing have been growing in popularity, spreading their influence into the library sphere. This article explores the confluence of these two trends by surveying the current literature on usability studies of digital libraries. This article focuses on the methodology of studies of multimedia digital libraries. (Contains 1 table and 45 notes.)

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... Research Center, Washington DC May 23 BBC NEws: US used Nuclear Weapons in Afghanistan Jalalabad: New reference levels based on recent samples show uranium levels 45 times normal. New bioassay studies identify uranium internal contamination in Spin Gar (Tora Bora) area and the City ...

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CEA is a public body devoted to technological research with 9 research centers throughout France. The activities of its 16,000 scientists, engineers, and technicians deal with new technologies for nuclear energy and alternative energies (fuel batteries, solar energy, energy storage) as well as technologies related to the new economy, in particular in the fields of microelectronics, bio-technologies, and materials. (author)

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Programs in coal research by the Pittsburgh Energy Technology Center are discussed. Topics include: Coal Science and Chemistry, Coal Liquefaction, Alternative Fuels, Coal Preparation, Combustion, MHD Program, Flue Gas Cleanup, Environmental Coordination, and Technology Transfer. (CBS)

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Material related to routine as well as sensitive aspects of parent/day care center relationships is presented in this training module, one of a series providing staff development information for programs operated for dependents of military personnel. The module offers a brief discussion of ways caregivers can help parents feel at ease about leaving their children in child care and presents a set of multiple-choice skill-building exercises for effectively working with parents. Exercises focus on various topics, including how parents can be approached when their child may have a health problem, when child abuse or neglect is suspected, and when parental cooperation is needed to stop a child's undesirable or disruptive behavior. Exercises are also devoted to the questions of whether or not caregivers should act as advisors to parents or tell parents about their child's behavior at the center. Concluding exercises indicate how caregivers can ...

International Nuclear Information System (INIS)

This study presents a dynamic analysis of a rotor supported by two turbulent flow model journal bearings and lubricated with couple stress fluid under nonlinear suspension. The dynamics of the rotor center and bearing center is studied. The dynamic equations are solved using the Runge-Kutta method. The analysis methods employed in this study is inclusive of the dynamic trajectories of the rotor center and bearing center, power spectra, Poincare maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The results show that the values of dimensionless parameters l* strongly influence dynamic motions of bearing and rotor centre. It is found that couple stress fluid improve the stability of the system when l* > 0.4 even if the flow of this system is turbulent. We also demonstrated that the dimensionless rotational speed ratios s and the ...

International Nuclear Information System (INIS)

This study presents a dynamic analysis of a flexible rotor supported by two porous squeeze couple stress fluid film journal bearings with non-linear suspension. The dynamics of the rotor center and bearing center are studied. The analysis of the rotor-bearing system is investigated under the assumptions of non-Newtonian fluid and a short bearing approximation. The spatial displacements in the horizontal and vertical directions are considered for various non-dimensional speed ratios. The dynamic equations are solved using the Runge-Kutta method. The analysis methods employed in this study is inclusive of the dynamic trajectories of the rotor center and bearing center, power spectra, Poincare maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The numerical results show that the stability of the system varies with the non-dimensional ...

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 ...

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

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 antimatter with a precision of the order of $10^{-8}$). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, 15 2006 in a $350\\times 600 km$ orbit with an inclination of 70 degrees. The detector is composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, Time-of-Flight and rigidity information. Lepton/hadron identification is performed by a Silicon-Tungsten calorimeter and a Neutron detector placed at the bottom of the device. An Anticounter system is used offline to reject false triggers coming from the satellite. In self-trigger ...

CERN Document Server

We study the stellar and dust properties of a well-defined sample of local elliptical galaxies to investigate the relationship between host galaxy properties and nuclear activity. We select a complete sample of 45 ellipticals from the Palomar spectroscopic survey of nearby galaxies, which includes 20 low-luminosity active galactic nuclei classified as LINERs and 25 inactive galaxies. Using a stellar population synthesis method, we compare the derived stellar population properties of the LINER versus the inactive subsamples. We also study the dust and stellar surface brightness distributions of the central regions of these galaxies using high-resolution images obtained with the {\\it Hubble Space Telescope}. Relative to the inactive subsample, ellipticals hosting LINERs share similar total optical and near-infrared luminosity, central stellar velocity dispersions, and nuclear stellar populations as judged from their luminosity-weighted ages and metallicities. ...

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The data obtained by the recent modern sky surveys enable detailed studies of the stellar distribution in the multi-dimensional space spanned by spatial coordinates, velocity and metallicity, from the solar neighborhood all the way out to the outer Milky Way halo. While these results represent exciting observational breakthroughs, their interpretation is not simple. For example, traditional decomposition of the thin and thick disks predicts a strong correlation in metallicity and kinematics at $\\sim$1 kpc from the Galactic plane; however, recent SDSS--based work has demonstrated an absence of this correlation for disk stars. Instead, the variation of the metallicity and rotational velocity distributions can be modeled using non--Gaussian functions that retain their shapes and only shift as the distance from the mid--plane increases. To fully contextualize these recent observational results, a detailed comparison with sophisticated numerical models is necessary. ...

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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 algorithm is its simplicity, its ability to work using function values solely, as well as its ability to ...

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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 brown dwarfs, which at ...

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 antimatter with a precision of the order of 10^-8). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, 15, 2006 in a 350*600 km orbit with an inclination of 70 degrees. The detector is composed of a series of scintillator counters arranged at the extremities of a permanent magnet spectrometer to provide charge, Time-of-Flight and rigidity information. Lepton/hadron identification is performed by a Silicon-Tungsten calorimeter and a Neutron detector placed at the bottom of the device. An Anticounter system is used offline to reject false triggers coming from the satellite. In self-trigger mode the ...

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 ...

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)

The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production sites. COS-B observations of spectral hardening near point sources, and future high-resolution observations of galactic point ...

CERN Document Server

We present the X-ray properties of a sample of 17 radio sources observed with the Chandra X-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift range z=0.30--1.96, and one low-power radio-galaxy at z=0.064. No diffuse X-ray emission is present around the cores of the quasars, except for the nearby low-power galaxy that has diffuse emission on a scale and with a luminosity consistent with other FRIs. No high-amplitude, short-term variability is detected within the relatively short Chandra exposures. However, 1510-089 shows low-amplitude flux changes with a timescale of $\\sim$25 minutes. The X-ray spectra of the quasar cores are generally well described by a single power law model with Galactic absorption. However, in six quasars we find soft X-ray excess ...

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 ...

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... significantly lower limits of detection. The complex fluorescence spectra of these constructs indicated that only a portion ...

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... Attributes and limitations of the charac- terization framework are illustrated through comparison with experimental PLZT data. ...

Energy Technology Data Exchange (ETDEWEB)

Lawrence Livermore National Laboratory's Engineering Directorate has two primary discretionary avenues for its investment in technologies: the Laboratory Directed Research and Development (LDRD) program and the ''Tech Base'' program. This volume summarizes progress on the projects funded for technology-base efforts in FY2004. The Engineering Technical Reports exemplify Engineering's more than 50-year history of researching and developing (LDRD), and reducing to practice (technology-base) the engineering technologies needed to support the Laboratory's missions. Engineering has been a partner in every major program and project at the Laboratory throughout its existence, and has prepared for this role with a skilled workforce and technical resources. This accomplishment is well summarized by Engineering's mission: ''Enable program success today and ensure the Laboratory's vitality ...

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A database has been developed to contain the disposal limits for the E-Area Low Level Waste Facility (ELLWF). This database originates in the form of an EXCEL{copyright} workbook. The pertinent sheets are translated to PDF format using Adobe ACROBAT{copyright}. The PDF version of the database is accessible from the Solid Waste Division web page on SHRINE. In addition to containing the various disposal unit limits, the database also contains hyperlinks to the original references for all limits. It is anticipated that database will be revised each time there is an addition, deletion or revision of any of the ELLWF radionuclide disposal limits.

Energy Technology Data Exchange (ETDEWEB)

This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectonic-stratigraphic domains, named as Central Guyana (GCD) and Uatuma-Anaua (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajos or Tapajos-Parima, Central Amazonian and Maroni-Itacaiunas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphic constraints on the granitoid rocks and contribute to a better understanding of the origin and geo dynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of Cd (1.96-1.93 ...

British Library Electronic Table of Contents (United Kingdom)

The X-ray storage phosphor CsBr:Eu2+ in form of needle image plates is believed to be a promising alternative to the granular BaFBr:Eu2+ with regard to PSL yield and spatial resolution. Unfortunately, CsBr:Eu2+ exhibits poor radiation hardness, which is caused by a migration of europium ions initiated by naturally existing defect centers like (Eu2+-VCs)-centers and X-ray generated MEu-centers. It will be shown that the formation of (Eu2+-O2?)-dipoles at the expense of (Eu2+-VCs)-dipoles, incorporated by thermal annealing in O2-containing and humid atmosphere, does not improve the radiation stability. There is, however, a strong improvement in the radiation hardness by codoping of CsBr:Eu2+ with lithium ions, which is accompanied by a complete suppression of the previously observed MEu-cent...

Science.gov (United States)

This final scientific report documents the Industrial Technology Program (ITP) Stage 2 Concept Development effort on Data Center Energy Reduction and Management Through Real-Time Optimal Control (RTOC). Society is becoming increasingly dependent on information technology systems, driving exponential growth in demand for data center processing and an insatiable appetite for energy. David Raths noted, 'A 50,000-square-foot data center uses approximately 4 megawatts of power, or the equivalent of 57 barrels of oil a day1.' The problem has become so severe that in some cases, users are giving up raw performance for a better balance between performance and energy efficiency. Historically, power systems for data centers were crudely sized to meet maximum demand. Since many servers operate at 60%-90% of maximum power while only utilizing an average of 5% to 15% of their capability, there are ...

Science.gov (United States)

The introduction of numerical control (NC) machine tools has made it possible to automate machining in series and small series production. The organization of automated production sections merged NC machine tools with automated transport systems. However, both the one and the other require the presence of an operative at the machine for low skilled operations. Industrial robots perform a number of auxiliary operations, such as equipment loading-unloading and control, changing cutting and auxiliary tools, controlling workpieces and parts, and cleaning of location surfaces. When used with a group of equipment they perform transfer operations between the machine tools. Industrial robots eliminate the need for workers to form auxiliary operations. This underscores the importance of developing robotized manufacturing centers providing for minimal human participation in production and creating conditions for two and three shift operation of equipment. Work carried out at ...

Science.gov (United States)

Bioethics--the study of ethical issues in science and medicine--has grown to become a significant academic and service-oriented discipline with its own research centers, conferences, journals, and degree programs. As these issues have moved to the center of public debate, the law has assumed an increasingly important place in the discipline of bioethics. Today, embryonic stem cell research stands out as a critically important issue about which the U.S. has neither ethical consensus nor clear, comprehensive regulation. The ethical debate centers on the fact that stem cell research involves the destruction of very early human embryos. This article provides a brief scientific background followed by a discussion of key ethical and legal/regulatory issues that surround embryonic stem cell research.

International Nuclear Information System (INIS)

Development and deployment of small-scale nuclear power reactors and their maintenance, monitoring, and control are part of the mission under the Small Modular Reactor (SMR) program. The objectives of this NERI-consortium research project are to investigate, develop, and validate advanced methods for sensing, controlling, monitoring, diagnosis, and prognosis of these reactors, and to demonstrate the methods with application to one of the proposed integral pressurized water reactors (IPWR). For this project, the IPWR design by Westinghouse, the International Reactor Secure and Innovative (IRIS), has been used to demonstrate the techniques developed under this project. The research focuses on three topical areas with the following objectives. Objective 1 - Develop and apply simulation capabilities and sensitivity/uncertainty analysis methods to address sensor deployment analysis and small grid stability issues. Objective 2 - Develop and test an autonomous and fault-tolerant control ...

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Power system analysis shows the output from the solar arrays varies as a function .... Each array corresponds to a raw image browse product, which is generated by .... low outgassing, ability to withstand long-term exposure to the space ...

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Summary of personnel, commitments, and costs ... Origin of complex land-based ecosystems (W. Friedman) ...... technology has brought about the birth of lab- ..... Baross, J.A. and S.E. Hoffman, Submarine hydrothermal vents and ...

UK PubMed Central (United Kingdom)

OBJECTIVE: The objective was to define and characterize the costs associated with trauma care at a level I trauma center. Once the costs were identified, attending physician-led teams were designed...Full Text Available

UK PubMed Central (United Kingdom)

Thioredoxin, a small, ubiquitous protein which participates in redox reactions through the reversible oxidation of its active center dithiol to a disulfide, is an essential protein in Bacillus...Full Text Available

UK PubMed Central (United Kingdom)

Patient-centered interdisciplinary health care for children with chronic medical disorders represents an evolution from the traditional “stop and go” treatment for acute illnesses. This...Full Text Available

UK PubMed Central (United Kingdom)

The effects of response effort on safe behaviors (i.e., glove wearing, hand sanitizing, and electrical outlet replacement) exhibited by therapists at an autism treatment center were examined. Participants...Full Text Available

UK PubMed Central (United Kingdom)

Accompanying rapid developments in hepatic surgery, the number of surgeries and identifications of histological types of primary hepatic space-occupying lesions (PHSOLs) have increased dramatically....Full Text Available

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May 18, 2001 ... Jeff Ashby, a Navy captain and veteran of ..... with the Department of Defense to acquire enough ..... Protection Handbook (Chapter 404). Each ..... x35416 or go to the website: http://www.ghg.net/cbr/jscas/ ...