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Sample records for bright spatially-coherent compact

  1. A Bright Spatially-Coherent Compact X-ray Synchrotron Source

    CERN Document Server

    Kneip, S; Martins, J L; Martins, S F; Bellei, C; Chvykov, V; Dollar, F; Fonseca, R; Huntington, C; Kalintchenko, G; Maksimchuk, A; Mangles, S P D; Matsuoka, T; Nagel, S R; Palmer, C; Schreiber, J; Phuoc, K Ta; Thomas, A G R; Yanovsky, V; Silva, L O; Krushelnick, K; Najmudin, Z

    2009-01-01

    Each successive generation of x-ray machines has opened up new frontiers in science, such as the first radiographs and the determination of the structure of DNA. State-of-the-art x-ray sources can now produce coherent high brightness keV x-rays and promise a new revolution in imaging complex systems on nanometre and femtosecond scales. Despite the demand, only a few dedicated synchrotron facilities exist worldwide, partially due the size and cost of conventional (accelerator) technology. Here we demonstrate the use of a recently developed compact laser-plasma accelerator to produce a well-collimated, spatially-coherent, intrinsically ultrafast source of hard x-rays. This method reduces the size of the synchrotron source from the tens of metres to centimetre scale, accelerating and wiggling a high electron charge simultaneously. This leads to a narrow-energy spread electron beam and x-ray source that is >1000 times brighter than previously reported plasma wiggler and thus has the potential to facilitate a myri...

  2. Compact and spatially coherent X-ray source based on cryogenic ERL. Basic design of the X-ray radiator

    International Nuclear Information System (INIS)

    The development of spatially coherent X-ray generator based on the compact energy recovery linac (ERL) has been studied in collaboration with Nihon University, High Energy Accelerator Research Organization (KEK) and Toyama. In this novel source, parametric X-ray radiation (PXR), which is a radiation phenomenon caused by the interaction between a charged particle and a crystal medium, is used for X-ray production. Thus, a thin crystal plate such as silicon or diamond irradiated with the electron beam from the ERL acts as an X-ray radiator. Since the acceptance of the deceleration tube restricts the emittance growth of the electron beam at the radiator, we define the maximum thickness of the radiator crystal as 0.2 mm. Under this condition, the properties of the available PXR beam were investigated using Monte Carlo simulations. The results show possibility of X-ray photon rate higher than 109 /s when the electron beam current is 30 μA. (author)

  3. Spatial coherence of random laser emission.

    Science.gov (United States)

    Redding, Brandon; Choma, Michael A; Cao, Hui

    2011-09-01

    We experimentally studied the spatial coherence of random laser emission from dye solutions containing nanoparticles. The spatial coherence, measured in a double slit experiment, varied significantly with the density of scatterers and the size and shape of the excitation volume. A qualitative explanation is provided, illustrating the dramatic difference from the spatial coherence of a conventional laser. This work demonstrates that random lasers can be controlled to provide intense, spatially incoherent emission for applications in which spatial cross talk or speckle limit performance.

  4. Compact stacking of diode lasers for pulsed light sources of high brightness.

    Science.gov (United States)

    Alahautala, Taito; Lassila, Erkki; Hernberg, Rolf

    2004-07-20

    A compact stacking architecture for high-power diode-laser arrays is proposed and compared with traditional stacks. The objective of compact stacking is to achieve high brightness values without the use of microlenses. The calculated brightness for a compact stack is over 300 W mm(-2) sr(-1), which is approximately 40 times higher than that of a traditional stack made of similar laser emitters. Even higher brightness values of over 600 W mm(-2) sr(-1) were reached in practice. A laser head was manufactured in which the light from several compact laser stacks could be fiber coupled or the light could be transformed to a highly uniform beam.

  5. A Compact High-Brightness Heavy-Ion Injector

    CERN Document Server

    Westenskow, Glen; Grote, D P; Halaxa, Erni; Kwan, Joe W

    2005-01-01

    To provide compact high-brightness heavy-ion beams for Heavy Ion Fusion (HIF) accelerators, we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. In an 80-kV 20-microsecond experiment, the RF plasma source has produced up to 5 mA of Ar+ in a single beamlet. An extraction current density of 100 mA/cm2 was achieved, and the thermal temperature of the ions was below 1 eV. More than 90% of the ions were in the Ar+ state, and the energy spread from charge exchange was found to be small. We have tested at full voltage gradient the first 4 gaps of a 61-beamlet injector design. Einzel lens were used to focus the beamlets while reducing the beamlet to beamlet space charge interaction. We will report on a converging 119 multi-beamlet source. Although the source has the same optics as a full 1.6 MV injector system, the test will be carried out at 400 kV due to the test stand HV limit. We will measure the beam’s emittance after the beamlets are merged and have bee...

  6. Spatial coherence of random laser emission

    CERN Document Server

    Redding, Brandon; Cao, Hui

    2011-01-01

    We experimentally studied the spatial coherence of random laser emission from dye solutions containing nanoparticles. The spatial coherence, measured in a double-slit experiment, varied significantly with the density of scatterers and the size and shape of the excitation volume. A qualitative explanation is provided, illustrating the dramatic difference from the spatial coherence of a conventional laser. This work demonstrates that random lasers can be controlled to provide intense, spatially incoherent emission for applications in which spatial cross talk or speckle limit performance.

  7. Topological Properties of Spatial Coherence Function

    Institute of Scientific and Technical Information of China (English)

    REN Ji-Rong; ZHU Tao; DUAN Yi-Shi

    2008-01-01

    The topological properties of the spatial coherence function are investigated rigorously.The phase singular structures(coherence vortices)of coherence function can be naturally deduced from the topological current,which is an abstract mathematical object studied previously.We find that coherence vortices are characterized by the Hopf index and Brouwer degree in topology.The coherence flux quantization and the linking of the closed coherence vortices are also studied from the topological properties of the spatial coherence function.

  8. Compact collimators for high brightness blue LEDs using dielectric multilayers

    NARCIS (Netherlands)

    Cornelissen, H.J.; Ma, H.; Ho, C.; Li, M.; Mu, C.

    2011-01-01

    A novel method is presented to inject the light of millimeter-sized high-brightness blue LEDs into light guides of submillimeter thickness. Use is made of an interference filter that is designed to pass only those modes that will propagate in the light guide by total internal reflection. Other modes

  9. Partially coherent imaging and spatial coherence wavelets

    CERN Document Server

    Castaneda, R

    2003-01-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function.

  10. Beam shaping design for compact and high-brightness fiber-coupled laser-diode system.

    Science.gov (United States)

    Yu, Junhong; Guo, Linui; Wu, Hualing; Wang, Zhao; Tan, Hao; Gao, Songxin; Wu, Deyong; Zhang, Kai

    2015-06-20

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. A compact and high-brightness fiber-coupled system has been designed based on a significant beam shaping method. The laser-diode stack consists of eight mini-bars and is effectively coupled into a standard 100 μm core diameter and NA=0.22 fiber. The simulative result indicates that the module will have an output power over 440 W. Using this technique, compactness and high-brightness production of a fiber-coupled laser-diode module is possible.

  11. A compact high brightness laser synchrotron light source for medical applications

    International Nuclear Information System (INIS)

    The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy

  12. Demonstration of a bright and compact source of tripartite nonclassical light

    OpenAIRE

    Allevi, Alessia; Bondani, Maria; Paris, Matteo G. A.; Andreoni, Alessandra

    2008-01-01

    We experimentally demonstrate the nonclassical photon number correlations expected in tripartite continuous variable states obtained by parametric processes. Our scheme involves a single nonlinear crystal, where two interlinked parametric interactions take place simultaneously, and represents a bright and compact source of a sub-shot-noise tripartite light field. We analyze the effects of the pump intensities on the numbers of detected photons and on the amount of noise reduction in some deta...

  13. Low spatial coherence electrically pumped semiconductor laser for speckle-free full-field imaging.

    Science.gov (United States)

    Redding, Brandon; Cerjan, Alexander; Huang, Xue; Lee, Minjoo Larry; Stone, A Douglas; Choma, Michael A; Cao, Hui

    2015-02-01

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ∼1,000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, which combines the low spatial coherence of a LED with the high spectral radiance of a laser, could enable a wide range of high-speed, full-field imaging and projection applications. PMID:25605946

  14. Stellar Systems in the direction of the Hickson Compact Group 44 - I. Low Surface Brightness Galaxies

    CERN Document Server

    Castelli, A V Smith; Escudero, C G

    2016-01-01

    Context. In spite of the numerous studies of low-luminosity galaxies in different environments, there is still no consensus about their formation scenario. In particular, a large number of galaxies displaying extremely low-surface brightnesses have been detected in the last year, and the nature of these objects is under discussion. Aims. In this paper we report the detection of two extended low-surface brightness (LSB) objects (mueff_g'~27 mag) found, in projection, next to NGC 3193 and in the zone of the Hickson Compact Group (HCG) 44, respectively. Methods. We analyzed deep, high-quality, GEMINI-GMOS images with ELLIPSE within IRAF in order to obtain their brightness profiles and structural parameters. We also search for the presence of globular clusters (GC) in these fields. Results. We have found that, if these LSB galaxies were at the distances of NGC 3193 and HCG 44, they would show sizes and luminosities similar to those of the ultra-diffuse galaxies (UDGs) found in the Coma cluster and other associati...

  15. Ultra high brightness laser diode arrays for pumping of compact solid state lasers and direct applications

    Science.gov (United States)

    Kohl, Andreas; Fillardet, Thierry; Laugustin, Arnaud; Rabot, Olivier

    2012-10-01

    High Power Laser Diodes (HPLD) are increasingly used in different fields of applications such as Industry, Medicine and Defense. Our significant improvements of performances (especially in power and efficiency) and a reproducible manufacturing process have led to reliable, highly robust components. For defense and security applications these devices are used predominantly for pumping of solid state lasers (ranging, designation, countermeasures, and sensors). Due to the drastically falling price per watt they are more and more replacing flash lamps as pump sources. By collimating the laser beam even with a bar to bar pitch of only 400μm. cutting edge brightness of our stacks.is achieved Due the extremely high brightness and high power density these stacks are an enabling technology for the development of compact highly efficient portable solid state lasers for applications as telemeters and designators on small platforms such as small UAVs and handheld devices. In combination with beam homogenizing optics their compact size and high efficiency makes these devices perfectly suited as illuminators for portable active imaging systems. For gated active imaging systems a very short pulse at high PRF operation is required. For this application we have developed a diode driver board with an efficiency several times higher than that of a standard driver. As a consequence this laser source has very low power consumption and low waste heat dissipation. In combination with its compact size and the integrated beam homogenizing optics it is therefore ideally suited for use in portable gated active imaging systems. The kWatt peak power enables a range of several hundred meters. The devices described in this paper mostly operate at wavelength between 800 nm and 980nm. Results from diodes operating between 1300 nm and 1550 nm are presented as well.

  16. Simple, compact, high brightness source for x-ray lithography and x-ray radiography

    International Nuclear Information System (INIS)

    A simple, compact, high brightness x-ray source has recently been built. This source utilizes a commercially available, cylindrical geometry electron beam evaporator, which has been modified to enhance the thermal cooling to the anode. Cooling is accomplished by using standard, low-conductivity laboratory water, with an inlet pressure of less than 50 psi, and a flow rate of approx.0.3 gal/min. The anode is an inverted cone geometry for efficient cooling. The x-ray source has a measured sub-millimeter spot size (FWHM). The anode has been operated at 1 KW e-beam power (10 KV, 100 ma). Higher operating levels will be investigated. A variety of different x-ray lines can be obtained by the simple interchange of anodes of different materials. Typical anodes are made from easily machined metals, or materials which are vacuum deposited onto a copper anode. Typically, a few microns of material is sufficient to stop 10 KV electrons without significantly decreasing the thermal conductivity through the anode. The small size and high brightness of this source make it useful for step and repeat exposures over several square centimeter areas, especially in a research laboratory environment. For an aluminum anode, the estimated Al-K x-ray flux at 10 cms from the source is 70 μW/cm2

  17. Low-spatial coherence electrically-pumped semiconductor laser for speckle-free full-field imaging

    CERN Document Server

    Redding, B; Huang, X; Lee, M L; Stone, A D; Choma, M A; Cao, H

    2014-01-01

    The spatial coherence of laser sources has limited their application to parallel imaging and projection due to coherent artifacts, such as speckle. In contrast, traditional incoherent light sources, such as thermal sources or light emitting diodes (LEDs), provide relatively low power per independent spatial mode. Here, we present a chip-scale, electrically-pumped semiconductor laser based on a novel design, demonstrating high power per mode with much lower spatial coherence than conventional laser sources. The laser resonator was fabricated with a chaotic, D-shaped cavity optimized to achieve highly multimode lasing. Lasing occurs simultaneously and independently in ~1000 modes, and hence the total emission exhibits very low spatial coherence. Speckle-free full-field imaging is demonstrated using the chaotic cavity laser as the illumination source. The power per mode of the sample illumination is several orders of magnitude higher than that of a LED or thermal light source. Such a compact, low-cost source, wh...

  18. Lens coupled tunable Young's double pinhole system for hard X-ray spatial coherence characterization.

    Science.gov (United States)

    Lyubomirskiy, Mikhail; Snigireva, Irina; Snigirev, Anatoly

    2016-06-13

    We have implemented a modified Young's double slit experiment using pinholes with tunable separation distance coupled with compound refractive lens for hard X-ray spatial coherence characterization. Varying distance between the apertures provides a high sensitivity to the determination of spatial coherence across a wide range of experimental parameters. The use of refractive lenses as a Fourier transformer ensures far field registration conditions and allows the realization of a very compact experimental setup in comparison with the classical Young technique and its derivatives. The tunable double aperture interferometer was experimentally tested at the ESRF ID06 beamline in the energy range from 8 to 25 keV. The spatial coherence and the source size were measured by evaluating the visibility of the interference fringes at various separation distances between the apertures and this value agrees very well with the data obtained by other techniques. The proposed scheme can be used for comprehensive characterization of the coherence properties of the source on low emittance synchrotrons in the hard X-ray region.

  19. A Search for Low Surface Brightness Structure Around Compact Narrow Emission Line Galaxies

    CERN Document Server

    Barton, E J; Bershady, M A; Barton, Elizabeth J.; Zee, Liese van; Bershady, Matthew A.

    2006-01-01

    As the most extreme members of the rapidly evolving faint blue galaxy population at intermediate redshift, the compact narrow emission line galaxies (CNELGs) are intrinsically luminous (-22 -18). Conversely, 15 are not blue enough to fade to low-luminosity dwarfs (M_B > -15.2). The majority of the CNELGs are consistent with progenitors of intermediate-luminosity dwarfs and low-luminosity spiral galaxies with small disks. CNELGs are a heterogeneous progenitor population with significant fractions (up to 44%) capable of fading into today's faint dwarfs (M_B > -15.2), while 15 to 85% may only experience an apparently extremely compact CNELG phase at intermediate redshift but remain more luminous galaxies at the present epoch.

  20. Spatial coherence of polaritons in a 1D channel

    Energy Technology Data Exchange (ETDEWEB)

    Savenko, I. G., E-mail: savenko.j@mail.ru [Russian Academy of Sciences, Academic University, Research and Education Center of Nanotechnologies (Russian Federation); Iorsh, I. V. [National Research University of Information Technologies, Mechanics and Optics (Russian Federation); Kaliteevski, M. A. [Russian Academy of Sciences, Academic University, Research and Education Center of Nanotechnologies (Russian Federation); Shelykh, I. A. [University of Iceland, Science Institute (Iceland)

    2013-01-15

    We analyze time evolution of spatial coherence of a polariton ensemble in a quantum wire (1D channel) under constant uniform resonant pumping. Using the theoretical approach based on the Lindblad equation for a one-particle density matrix, which takes into account the polariton-phonon and excitonexciton interactions, we study the behavior of the first-order coherence function g{sup 1} for various pump intensities and temperatures in the range of 1-20 K. Bistability and hysteresis in the dependence of the first-order coherence function on the pump intensity is demonstrated.

  1. Transient Aspects of Wave Propagation Connected with Spatial Coherence

    Directory of Open Access Journals (Sweden)

    Ezzat G. Bakhoum

    2013-01-01

    Full Text Available This study presents transient aspects of light wave propagation connected with spatial coherence. It is shown that reflection and refraction phenomena involve spatial patterns which are created within a certain transient time interval. After this transient time interval, these patterns act like a memory, determining the wave vector for subsequent sets of reflected/refracted waves. The validity of this model is based on intuitive aspects regarding phase conservation of energy for waves reflected/refracted by multiple centers in a certain material medium.

  2. Determining the Spectral Signature of Spatial Coherent Structures

    CERN Document Server

    Pastur, L R; Fraigneau, Y; Podvin, B

    2005-01-01

    We applied to an open flow a proper orthogonal decomposition (pod) technique, on 2D snapshots of the instantaneous velocity field, to reveal the spatial coherent structures responsible of the self-sustained oscillations observed in the spectral distribution of time series. We applied the technique to 2D planes out of 3D direct numerical simulations on an open cavity flow. The process can easily be implemented on usual personal computers, and might bring deep insights on the relation between spatial events and temporal signature in (both numerical or experimental) open flows.

  3. On the nature of bright compact radio sources at z>4.5

    Science.gov (United States)

    Coppejans, Rocco; Frey, Sándor; Cseh, Dávid; Müller, Cornelia; Paragi, Zsolt; Falcke, Heino; Gabányi, Krisztina É.; Gurvits, Leonid I.; An, Tao; Titov, Oleg

    2016-09-01

    High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early universe and understand galaxy evolution. Prior to this paper, 20 extragalactic radio sources at redshifts above 4.5 have been imaged with very long baseline interferometry (VLBI). Here we report on observations of an additional ten z > 4.5 sources at 1.7 and 5 GHz with the European VLBI Network (EVN), thereby increasing the number of imaged sources by 50 per cent. Combining our newly observed sources with those from the literature, we create a substantial sample of 30 z > 4.5 VLBI sources, allowing us to study the nature of these objects. Using spectral indices, variability and brightness temperatures, we conclude that of the 27 sources with sufficient information to classify, the radio emission from one source is from star formation, 13 are flat-spectrum radio quasars and 13 are steep-spectrum sources. We also argue that the steep-spectrum sources are off-axis (unbeamed) radio sources with rest-frame self-absorption peaks at or below GHz frequencies and that these sources can be classified as gigahertz peaked-spectrum (GPS) and megahertz peaked-spectrum (MPS) sources.

  4. On the nature of bright compact radio sources at z>4.5

    CERN Document Server

    Coppejans, Rocco; Cseh, Dávid; Müller, Cornelia; Paragi, Zsolt; Falcke, Heino; Gabányi, Krisztina É; Gurvits, Leonid I; An, Tao; Titov, Oleg

    2016-01-01

    High-redshift radio-loud quasars are used to, among other things, test the predictions of cosmological models, set constraints on black hole growth in the early universe and understand galaxy evolution. Prior to this paper, 20 extragalactic radio sources at redshifts above 4.5 have been imaged with very long baseline interferometry (VLBI). Here we report on observations of an additional ten z>4.5 sources at 1.7 and 5 GHz with the European VLBI Network (EVN), thereby increasing the number of imaged sources by 50%. Combining our newly observed sources with those from the literature, we create a substantial sample of 30 z>4.5 VLBI sources, allowing us to study the nature of these objects. Using spectral indices, variability and brightness temperatures, we conclude that of the 27 sources with sufficient information to classify, the radio emission from one source is from star formation, 13 are flat-spectrum radio quasars and 13 are steep-spectrum sources. We also argue that the steep-spectrum sources are off-axis ...

  5. Spatial coherence of thermal photons favors photosynthetic life

    CERN Document Server

    Manrique, Pedro; Caycedo-Soler, Felipe; Rodríguez, Ferney; Quiroga, Luis; Johnson, Neil

    2015-01-01

    Harvesting of sunlight underpins Life on Earth as well as driving novel energy device design. Though several experiments suggest that excitation energy transport and charge separation within a photosynthetic membrane may benefit from the quantum nature of their dynamics, the effects of spatial coherences in the incident light have been largely ignored. Here we show that spatial correlations in the incident light likely play an important role in trapping light and adding robustness, as well as providing a driving mechanism for an organism's adaptation toward more ordered structures. Our theory is grounded by empirical inputs, while its output is validated against testable predictions. Our results suggest that spatiotemporal correlations between photons, a fundamental property of the quantum world, should play a key role in our understanding of early Life and in improving the design of artificial photosynthetic systems.

  6. The spatial coherence of Schumann activity in the polar cap

    Science.gov (United States)

    Holtham, P. M.; McAskill, B. J.

    1988-02-01

    The spatial coherence of the first two Schumann resonant modes has been studied at two locations in the polar cap separated by 1100 km. Measurements were made at Assistance Bay and Mould Bay, which have geomagnetic latitudes of 83 and 79 deg, respectively, and satellite time-keeping was employed to accurately synchronize the field stations. The coherence was found to be high, typically 95 percent for the first Schumann mode, and was unaffected by changes in Kp, a storm sudden commencement, or a solar flare event. Polarization rotations were observed between the two stations, which could most likely be attributed to the coastline effect. The results are consistent with a stable propagation of Schumann activity from midlatitudes to high latitudes that is relatively unaffected by changes in the polar cap ionosphere.

  7. Surface brightness profiles of blue compact dwarf galaxies in the GOODS-N and GOODS-S field

    CERN Document Server

    Lian, Jianhui; Jiang, Ning; Yan, Wei; Gao, Yulong

    2016-01-01

    We investigate the structural properties of the underlying hosts of 34 blue compact dwarf (BCD) galaxies with deep near-infrared (NIR) photometry. The BCD sample is selected from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey in the Great observatories origins Deep Survey North and South fields. We extract the surface brightness profile (SBP) in the optical F 435W and NIR F 160W bands. The SBPs of BCDs in the H band reach 26 mag arcsec^-2 at the 3\\sigma level, which is so far the deepest NIR imaging of BCDs. Then we fit the SBPs with one- and two- component Sersic models. About half of the BCDs favour the two-component model which significantly improves the fit quality. The effective radii of the underlying hosts of BCDs in the B band are smaller than those of early-type dwarfs (dEs) and dwarf irregulars at a fixed luminosity. This discrepancy is similar to findings in many previous works. However, the difference in structural parameters between BCDs and other dwarf galaxies seems to be less sig...

  8. Effects of spatial coherence in diffraction phase microscopy.

    Science.gov (United States)

    Edwards, Chris; Bhaduri, Basanta; Nguyen, Tan; Griffin, Benjamin G; Pham, Hoa; Kim, Taewoo; Popescu, Gabriel; Goddard, Lynford L

    2014-03-10

    Quantitative phase imaging systems using white light illumination can exhibit lower noise figures than laser-based systems. However, they can also suffer from object-dependent artifacts, such as halos, which prevent accurate reconstruction of the surface topography. In this work, we show that white light diffraction phase microscopy using a standard halogen lamp can produce accurate height maps of even the most challenging structures provided that there is proper spatial filtering at: 1) the condenser to ensure adequate spatial coherence and 2) the output Fourier plane to produce a uniform reference beam. We explain that these object-dependent artifacts are a high-pass filtering phenomenon, establish design guidelines to reduce the artifacts, and then apply these guidelines to eliminate the halo effect. Since a spatially incoherent source requires significant spatial filtering, the irradiance is lower and proportionally longer exposure times are needed. To circumvent this tradeoff, we demonstrate that a supercontinuum laser, due to its high radiance, can provide accurate measurements with reduced exposure times, allowing for fast dynamic measurements. PMID:24663853

  9. Robust spatial coherence 5 μ m from a room-temperature atom chip

    Science.gov (United States)

    Zhou, Shuyu; Groswasser, David; Keil, Mark; Japha, Yonathan; Folman, Ron

    2016-06-01

    We study spatial coherence near a classical environment by loading a Bose-Einstein condensate into a magnetic lattice potential and observing diffraction. Even very close to a surface (5 μ m ), and even when the surface is at room temperature, spatial coherence persists for a relatively long time (≥500 ms ). In addition, the observed spatial coherence extends over several lattice sites, a significantly greater distance than the atom-surface separation. This opens the door for atomic circuits, and may help elucidate the interplay between spatial dephasing, interatomic interactions, and external noise.

  10. Spatial coherences of the sound pressure and the particle velocity in underwater ambient noise

    Institute of Scientific and Technical Information of China (English)

    YAN Jin; LUO Xianzhi; HOU Chaohuan

    2007-01-01

    The spatial coherences were investigated between the sound pressure and the three orthogonal components of the particle velocity in underwater ambient noise. Based on the ray theory, integral expression was derived for the spatial coherence matrix of the sound pressure and the particle velocity in a stratified ocean with dipole noise sources homogenously distributed on the surface. The integrand includes a multiplying factor of the vertical directivity of the noise intensity, and the layered ocean environment affects the spatial coherences via this directivity factor. For a shallow water environment and a semi-infinite homogenous medium, the coherence calculation results were given. It was showed that the sound speed profile and the sea bottom could not be neglected in determining the spatial coherences of the ambient noise vector field.

  11. Experimental study of coherence vortices: Local properties of phase singularities in a spatial coherence function

    DEFF Research Database (Denmark)

    Wang, W.; Duan, Z.H.; Hanson, Steen Grüner;

    2006-01-01

    By controlling the irradiance of an extended quasimonochromatic, spatially incoherent source, an optical field is generated that exhibits spatial coherence with phase singularities, called coherence vortices. A simple optical geometry for direct visualization of coherence vortices is proposed, and...

  12. Optimising predictor domains for spatially coherent precipitation downscaling

    Science.gov (United States)

    Radanovics, S.; Vidal, J.-P.; Sauquet, E.; Ben Daoud, A.; Bontron, G.

    2012-04-01

    resulting optimised domains are analysed for defining regions where neighbouring zones have equal or similar predictor domains and identifying which French river basins contain zones associated with different predictor domains, i.e. are exposed to different meteorological influences. The above analysis will be used (1) to extend the statistical downscaling method of Ben Daoud et al. (2011) to the whole of France and (2) to develop it further in order to achieve spatially coherent forecasts while preserving the predictive skill on the local scale. Ben Daoud, A., Sauquet, E., Lang, M., Bontron, G., and Obled, C. (2011). Precipitation forecasting through an analog sorting technique: a comparative study. Advances in Geosciences, 29:103-107. doi: 10.5194/adgeo-29-103-2011 Obled, C., Bontron, G., and Garçon, R. (2002). Quantitative precipitation forecasts: a statistical adaptation of model outputs through an analogues sorting approach. Atmospheric Research, 63(3-4):303-324. doi: 10.1016/S0169-8095(02)00038-8 Vidal, J.-P., Martin, E., Franchistéguy, L., Baillon, M., and Soubeyroux, J.-M. (2010) A 50-year high-resolution atmospheric reanalysis over France with the Safran system. International Journal of Climatology, 30:1627-1644. doi: 10.1002/joc.2003

  13. Effect of spatial coherence on damage occurrence in multimode optical fibers.

    Science.gov (United States)

    Herzog, Amir; Malka, Dror; Zalevsky, Zeev; Ishaaya, Amiel A

    2015-02-01

    We investigate the influence of spatial coherence on damage occurrence in highly multimode optical fibers using ultraviolet (UV) nanosecond pulses, with the aim of delivering high fluence in the UV. In some cases, the optical damage is initiated below the fiber facet damage threshold and takes place along the propagation path; such damage is believed to be caused by local constructive interference, creating "hot spots." In order to reduce the degree of spatial coherence, we used a large-diameter core (1.5 mm) fiber as a mode scrambler. Different lengths of this large core fiber were used to deliver energy to a fiber core with a smaller diameter (0.6 mm), in which the damage occurrence was observed. The experimental results indicate that there is a correlation between the degree of spatial coherence and the occurrence of optical damages, typically observed a few millimeters from the fiber facet. Numerical simulations, based on the beam-propagation method, support the degradation of spatial coherence, due to the excitation of high-order modes. Finally, by degrading the spatial coherence of the beam, we establish a new record by delivering more than 100 mJ via a 1.5 mm core diameter fiber in the UV, corresponding to ∼26 times the critical power for self-focusing. Our work sheds light on the ability to deliver high energies of nanosecond-pulsed UV laser radiation through multimode optical fibers. PMID:25680061

  14. Atomic spatial coherence with spontaneous emission in a strong coupling cavity

    CERN Document Server

    Fang, Zhen; Zhou, Xiaoji; Chen, Xuzong

    2010-01-01

    The role of spontaneous emission in the interaction between a two-level atom and a pumped micro-cavity in the strong coupling regime is discussed in this paper. Especially, using a quantum Monte-Carlo simulation, we investigate atomic spatial coherence. It is found that atomic spontaneous emission destroys the coherence between neighboring lattice sites, while the cavity decay does not. Furthermore, our computation of the spatial coherence function shows that the in-site locality is little affected by the cavity decay, but greatly depends on the cavity pump amplitude.

  15. Measurement of Spatial Coherence of Light Propagating in a Turbulent Atmosphere

    Directory of Open Access Journals (Sweden)

    P. Barcik

    2013-04-01

    Full Text Available A lot of issues have to be taken into account when designing a reliable free space optical communication link. Among these are e.g.,beam wander, fluctuation of optical intensity and loss of spatial coherence that are caused by atmospheric turbulence. This paper presents experimental measurements of spatial coherence of a laser beam. The experimental setup is based on Young's double pinhole experiment. Fringe patterns under atmospheric turbulence for four different pinhole separations are presented. From these fringe patterns, visibility is determined and the coherence radius is estimated.

  16. New insights to the photometric structure of Blue Compact Dwarf Galaxies from deep Near-Infrared studies I. Observations, surface photometry and decomposition of surface brightness profiles

    CERN Document Server

    Noeske, K G; Cairos, L M; Fricke, K J

    2003-01-01

    (shortened) We analyze deep Near Infrared (NIR) broad band images for a sample of Blue Compact Dwarf Galaxies (BCDs), allowing for the quantitative study of their extended stellar low-surface brightness (LSB) host galaxies. NIR surface brightness profiles (SBPs) of the LSB hosts agree at large galactocentric radii with those from optical studies. At small to intermediate radii, however, the NIR data reveal for more than half of our sample a significant flattening of the exponential SBP of the LSB host. Such SBPs ("type V" SBPs, Binggeli & Cameron 1991) have rarely been detected in LSB hosts of BCDs at optical wavelengths, where the relative flux contribution of the starburst is stronger than in the NIR and can hide such central intensity depressions of the LSB host. The structural properties, frequency and physical origin of type V LSB SBPs in BCDs and other dwarf galaxies have not yet been systematically studied. Nevertheless, their occurrence in a significant fraction of BCDs would impose important new ...

  17. Non-approximated numerical modeling of propagation of light in any state of spatial coherence.

    Science.gov (United States)

    Castañeda, Román; Garcia-Sucerquia, Jorge

    2011-12-01

    Due to analytical and numerical difficulties, the propagation of optical fields in any state of spatial coherence is traditionally computed under severe approximations. The paraxial approach in the Fresnel-Fraunhofer domain is one of the most widely used. These approximations provide a rough knowledge of the actual light behavior as it propagates, which is not enough for supporting applications, such as light propagation under a high numerical aperture (NA). In this paper, a non-approximated model for the propagation of optical fields in any state of spatial coherence is presented. The method is applicable in very practical cases, as high-NA propagations, because of its simplicity of implementation. This approach allows for studying unaware behaviors of light as it propagates. The light behavior close to the diffracting transmittances can also be analyzed with the aid of the proposed tool.

  18. Spiral Waves and Multiple Spatial Coherence Resonances Induced by Colored Noise in Neuronal Network

    Institute of Scientific and Technical Information of China (English)

    唐昭; 李玉叶; 惠磊; 贾冰; 吉华光

    2012-01-01

    Gaussian colored noise induced spatial patterns and spatial coherence resonances in a square lattice neuronal network composed of Morris-Lecar neurons are studied. Each neuron is at resting state near a saddle-node bifurcation on invariant circle, coupled to its nearest neighbors by electronic coupling. Spiral waves with different structures and disordered spatial structures can be alternately induced within a large range of noise intensity. By calculating spatial structure function and signal-to-noise ratio (SNR), it is found that SNR values are higher when the spiral structures are simple and are lower when the spatial patterns are complex or disordered, respectively. SNR manifest multiple local maximal peaks, indicating that the colored noise can induce multiple spatial coherence resonances. The maximal SNR values decrease as the correlation time of the noise increases. These results not only provide an example of multiple resonances, but also show that Gaussian colored noise play constructive roles in neuronal network.

  19. Spatial Coherence of Impact Pressures at a Vertical Breakwater in Multidirectional Seas

    DEFF Research Database (Denmark)

    Sauer, W.; Löffler, A.; Kortenhaus, A.;

    " (LSF) includes the possibility for researchers to work at selected European large-scale facilities. Within this activity the project "Spatial coherence of impact pressures at a vertical breakwater in multidirectional seas" was founded and could therefore be performed by the University of Bologna...... (DISTART Idraulica, Italy [UoB]), Aalborg University (Hydraulics and Coastal Engineering Laboratory, Denmark [AU]) and Technical University of Braunschweig (Leichtweiss-Institut, Germany [LWI])....

  20. Equatorial spread {ital F} effects on an HF path: Doppler spread, spatial coherence, and frequency coherence

    Energy Technology Data Exchange (ETDEWEB)

    Fitzgerald, T.J.; Argo, P.E.; Carlos, R.C. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States)

    1999-01-01

    In August 1990 we participated in the Equatorial Ionospheric Studies sounding rocket campaign near Kwajalein Atoll in the equatorial Pacific region. The campaign included measurements of plasma density using rocket probes and coherent and incoherent scatter radar. During the campaign we fielded high-frequency ionospheric sounders over a bistatic path between Maloelap Atoll and Bikini Atoll in the Marshall Islands. The distance between the transmitters and receivers was 700 km; the ionospheric-reflection region was at 10.18; {degree}N, 168.40;{degree}E, near the magnetic equator. We made three types of measurements: Doppler spread and spatial coherence for a single-frequency CW path; frequency coherence of multiple CW paths; and Doppler spread and time-delay spread for a 60-kHz bandwidth path. We obtained such data over a period of 2 weeks for approximately 2 hours each evening; during this period spread {ital F} was common. Fifty percent of the evenings showed Doppler spread of greater than 6 Hz at the {minus}10 dB level (relative to the peak signal power) and greater than 15 Hz at the {minus}30 dB level. Forty percent of the evenings showed spatial coherence distance of less than 180 m in the direction normal to the bistatic path; 40{percent} of the evenings showed spatial coherence of less than 75 m in the direction parallel to the path. Seventy-five percent of the evenings showed coherence bandwidths of less than 1.5 kHz. {copyright} 1999 American Geophysical Union

  1. Equatorial spread F effects on an HF path: Doppler spread, spatial coherence, and frequency coherence

    International Nuclear Information System (INIS)

    In August 1990 we participated in the Equatorial Ionospheric Studies sounding rocket campaign near Kwajalein Atoll in the equatorial Pacific region. The campaign included measurements of plasma density using rocket probes and coherent and incoherent scatter radar. During the campaign we fielded high-frequency ionospheric sounders over a bistatic path between Maloelap Atoll and Bikini Atoll in the Marshall Islands. The distance between the transmitters and receivers was 700 km; the ionospheric-reflection region was at 10.18; degree N, 168.40;degree E, near the magnetic equator. We made three types of measurements: Doppler spread and spatial coherence for a single-frequency CW path; frequency coherence of multiple CW paths; and Doppler spread and time-delay spread for a 60-kHz bandwidth path. We obtained such data over a period of 2 weeks for approximately 2 hours each evening; during this period spread F was common. Fifty percent of the evenings showed Doppler spread of greater than 6 Hz at the -10 dB level (relative to the peak signal power) and greater than 15 Hz at the -30 dB level. Forty percent of the evenings showed spatial coherence distance of less than 180 m in the direction normal to the bistatic path; 40% of the evenings showed spatial coherence of less than 75 m in the direction parallel to the path. Seventy-five percent of the evenings showed coherence bandwidths of less than 1.5 kHz. copyright 1999 American Geophysical Union

  2. Polarization and spatial coherence of electromagnetic waves in uncorrelated disordered media

    CERN Document Server

    Vynck, Kevin; Carminati, Rémi

    2014-01-01

    Spatial field correlation functions represent a key quantity for the description of mesoscopic phenomena in disordered media and the optical characterization of complex materials. Yet many aspects related to the vector nature of light waves have not been investigated so far. We study theoretically the polarization and coherence properties of electromagnetic waves produced by a dipole source in a three-dimensional uncorrelated disordered medium. The spatial field correlation matrix is calculated analytically using a multiple scattering theory for polarized light. This allows us to provide a formal description of the light depolarization process in terms of "polarization eigenchannels" and to derive analytical formulas for the spatial coherence of multiply-scattered light.

  3. Water-soluble multidentate polymers compactly coating Ag2S quantum dots with minimized hydrodynamic size and bright emission tunable from red to second near-infrared region

    Science.gov (United States)

    Gui, Rijun; Wan, Ajun; Liu, Xifeng; Yuan, Wen; Jin, Hui

    2014-04-01

    Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in the bright fluorescent QDs with high PL quantum yields (QYs: 14.2-16.4%). Experimental results confirm that the QDs have high PL stability and ultralow cytotoxicity, as well as high PLQYs and small hydrodynamic sizes (4.5-5.6 nm) similar to fluorescent proteins (27-30 kDa), indicating the feasibility of highly effective PL imaging in cells and living animals.Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in

  4. Spatial Coherence Properties of Organic Molecules Coupled to Plasmonic Surface Lattice Resonances in the Weak and Strong Coupling Regimes

    CERN Document Server

    Shi, L; Rekola, H T; Martikainen, J -P; Moerland, R J; Törmä, P

    2014-01-01

    We study spatial coherence properties of a system composed of periodic silver nanoparticle arrays covered with a fluorescent organic molecule (DiD) film. The evolution of spatial coherence of this composite structure from the weak to the strong coupling regime is investigated by systematically varying the coupling strength between the localized DiD excitons and the collective, delocalized modes of the nanoparticle array known as surface lattice resonances. A gradual evolution of coherence from the weak to the strong coupling regime is observed, with the strong coupling features clearly visible in interference fringes. A high degree of spatial coherence is demonstrated in the strong coupling regime, even when the mode is very excitonlike (80%), in contrast to the purely localized nature of molecular excitons. We show that coherence appears in proportion to the weight of the plasmonic component of the mode throughout the weak-to-strong coupling crossover, providing evidence for the hybrid nature of the normal m...

  5. Recording of incoherent-object hologram as complex spatial coherence function using Sagnac radial shearing interferometer and a Pockels cell.

    Science.gov (United States)

    Naik, Dinesh N; Pedrini, Giancarlo; Osten, Wolfgang

    2013-02-25

    The ideas of incoherent holography were conceived after the invention of coherent-light holography and their concepts seems indirectly related to it. In this work, we adopt an approach based on statistical optics to describe the process of recording of an incoherent-object hologram as a complex spatial coherence function. A Sagnac radial shearing interferometer is used for the correlation of optical fields and a Pockels cell is used to phase shift the interfering fields with the objective to quantify and to retrieve the spatial coherence function.

  6. Characterization of Spatial Coherence of Synchrotron Radiation with Non-Redundant Arrays of Apertures

    OpenAIRE

    Skopintsev, P.; Singer, A.; Yefanov, Oleksandr; Glaser, L; Sakdinawat, A.; Grübel, G.; Frömter, R.; Oepen, H.P.; Viefhaus, J.; Vartanyants, I. A.; Bach, J.; MÜller, L.; Beyersdorff, B; Schleitzer, S.; Gorobtsov, Oleg

    2014-01-01

    We present a method to characterize the spatial coherence of soft X-ray radiation from a single diffraction pattern. The technique is based on scattering from non-redundant arrays (NRA) of slits and records the degree of spatial coherence at several relative separations from one to 15 microns, simultaneously. Using NRAs we measured the transverse coherence of the X-ray beam at the XUV X-ray beamline P04 of the PETRA III synchrotron storage ring as a function of different beam parameters. To v...

  7. An off-axis digital holographic microscope with quasimonochromatic partially spatially coherent illumination in transmission

    Science.gov (United States)

    Grebenyuk, Anton A.; Tarakanchikova, Yana V.; Ryabukho, Vladimir P.

    2014-10-01

    We propose an off-axis imaging approach for digital holographic microscopy (DHM) with quasimonochromatic partially spatially coherent illumination in transmission, which is intended to provide the advantages of off-axis partially coherent DHM imaging with a comparatively simple optical scheme. This approach does not require a diffraction grating for creating the off-axis modality and also allows for convenient control of the spatial frequency of carrier interference fringes for hologram sampling optimization. Theoretical analysis of the off-axis imaging process in this microscope is performed. An off-axis DHM based on the proposed approach is built and quantitative phase imaging of test objects is performed with suppressed coherent noise.

  8. A new spatial coherence model and analytical coefficients for multi-support response spectrum combination

    Institute of Scientific and Technical Information of China (English)

    Wang Junjie; Chen Hu

    2007-01-01

    In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination (correlation) coefficients of structural response are developed for multi-support seismic excitations. The coefficients from both the numerical integration and analytical solutions are compared to verify the accuracy of the solutions. It is shown that the analytical expressions of numerical modal combination coefficients are of high accuracy. The results of random responses of an example bridge show that the analytical modal combination coefficients developed in this paper are accurate enough to meet the requirements needed in practice. In addition, the computational efficiency of the analytical solutions of the modal combination coefficients is demonstrated by the response computation of the example bridge. It is found that the time required for the structural response analysis by using the analytical modal combination coefficients is less than 1/20 of that using numerical integral methods.

  9. Low-spatial-coherence broadband fiber source for speckle free imaging

    CERN Document Server

    Redding, Brandon; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-01-01

    We designed and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at {\\lambda}=1055 nm with a full-width half-maximum bandwidth of 74 nm. The emission is distributed among as many as ~70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  10. Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

    Science.gov (United States)

    Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

    2010-07-01

    We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

  11. Satellite measurements reveal strong anisotropy in spatial coherence of climate variations over the Tibet Plateau.

    Science.gov (United States)

    Chen, Deliang; Tian, Yudong; Yao, Tandong; Ou, Tinghai

    2016-01-01

    This study uses high-resolution, long-term satellite observations to evaluate the spatial scales of the climate variations across the Tibet Plateau (TP). Both land surface temperature and precipitation observations of more than 10 years were analysed with a special attention to eight existing ice-core sites in the TP. The temporal correlation for the monthly or annual anomalies between any two points decreases exponentially with their spatial distance, and we used the e-folding decay constant to quantify the spatial scales. We found that the spatial scales are strongly direction-dependent, with distinctive patterns in the west-east and south-north orientations, for example. Meanwhile, in the same directions the scales are largely symmetric backward and forward. Focusing on the west-east and south-north directions, we found the spatial coherence in the first is generally stronger than in the second. The annual surface temperature had typical spatial scales of 302-480 km, while the annual precipitation showed smaller scales of 111-182 km. The majority of the eight ice-core sites exhibit scales much smaller than the typical scales over the TP as a whole. These results provide important observational basis for the selection of appropriate downscaling strategies, deployment of climate-data collection networks, and interpreting paleoclimate reconstructions. PMID:27553388

  12. Ultra-short longitudinal spatial coherence length of laser light with the combined effect of spatial, angular, and temporal diversity

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Azeem, E-mail: ahmadazeem870@gmail.com, E-mail: mehtads@physics.iitd.ac.in; Dubey, Vishesh; Mehta, D. S., E-mail: ahmadazeem870@gmail.com, E-mail: mehtads@physics.iitd.ac.in [Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Srivastava, Vishal [Department of Electrical and Instrumentation Engineering, Thapar University, Patiala, Punjab 147004 (India)

    2015-03-02

    We demonstrate ultra-high axial-resolution topography and tomography of multilayered objects using pseudo thermal light source, i.e., laser. The longitudinal spatial coherence (LSC) length of light was significantly reduced by synthesizing a pseudo thermal source with the combined effect of spatial, angular, and temporal diversity. Thus, generating a low spatially coherent (i.e., broad angular frequency spectrum) light source having narrow temporal frequency spectrum. The LSC length was reduced less than 10 μm using a very low magnification lens. Experimental results of optical sectioning of multilayer objects with high axial-resolution of the order of 4 μm was achieved which is comparable to broadband light source. The present system does not require any dispersion compensation optical system for biological samples as a highly monochromatic light source is used.

  13. Defining predictand areas with homogeneous predictors for spatially coherent precipitation downscaling

    Science.gov (United States)

    Radanovics, Sabine; Vidal, Jean-Philippe; Sauquet, Eric; Ben Daoud, Aurélien; Bontron, Guillaume

    2013-04-01

    the 5 ones that lead to the highest CRPSS for the zone in question are retained. The 5 retained domains were found to be equally skillfull with a maximum difference of around 1% of CRPSS on average, and are thus all candidates for clustering predictand zones. An objective procedure has then been implemented for clustering zones together, based on their sharing a common predictor domain inside their 5 near-optimal domain ensemble. For zones sharing several near-optimal predictor domains, the aim was to minimise the number of disjoint predictand areas. Furthermore solutions that lead to more similar sized areas were preferred. This procedure defines areas with natural spatial coherence and reduces the number of different predictor domains using a procedure based on objective rules, unlike most of studies where this is done either subjectively or arbitrarily. It allowed to reduce significantly the number of independent zones and to identify large homogeneous areas encompassing relatively large river basins. Further developments will address the issue of spatial coherent downscaling for predictand areas that do not share any near-optimal predictor domains. Ben Daoud, A., Sauquet, E., Lang, M., Bontron, G., and Obled, C. (2011). Precipitation forecasting through an analog sorting technique: a comparative study. Advances in Geosciences, 29:103-107. doi: 10.5194/adgeo-29-103-2011 Timbal, B., Dufour, A., and McAvaney, B. (2003). An estimate of future climate change for western France using a statistical downscaling technique. Climate Dynamics, 20(7-8):807-823. doi: 10.1007/s00382-002-0298-9 Vidal, J.-P., Martin, E., Franchistéguy, L., Baillon, M., and Soubeyroux, J.-M. (2010) A 50-year high-resolution atmospheric reanalysis over France with the Safran system. International Journal of Climatology, 30:1627-1644. doi: 10.1002/joc.2003

  14. A novel imaging technique based on the spatial coherence of backscattered waves: demonstration in the presence of acoustical clutter

    Science.gov (United States)

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Lediju, Muyinatu; Trahey, Gregg E.

    2011-03-01

    In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are often attributed to phase aberration and clutter. Phase aberration degrades image quality by distorting the transmitted and received pressure waves, while clutter degrades image quality by introducing incoherent acoustical interference into the received pressure wavefront. Although significant research efforts have pursued the correction of image degradation due to phase aberration, few efforts have characterized or corrected image degradation due to clutter. We have developed a novel imaging technique that is capable of differentiating ultrasonic signals corrupted by acoustical interference. The technique, named short-lag spatial coherence (SLSC) imaging, is based on the spatial coherence of the received ultrasonic wavefront at small spatial distances across the transducer aperture. We demonstrate comparative B-mode and SLSC images using full-wave simulations that include the effects of clutter and show that SLSC imaging generates contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) that are significantly better than B-mode imaging under noise-free conditions. In the presence of noise, SLSC imaging significantly outperforms conventional B-mode imaging in all image quality metrics. We demonstrate the use of SLSC imaging in vivo and compare B-mode and SLSC images of human thyroid and liver.

  15. Mediatization, Spatial Coherence and Social Sustainability The Role of Digital Media Networks in a Swedish Countryside Community

    Directory of Open Access Journals (Sweden)

    André Jansson

    2010-06-01

    Full Text Available What does the implementation of new communication networks mean for the spa-tial coherence and social sustainability of rural communities? This paper takes its key from Wittel’s discussion of network sociality, understood as the opposite of Gemeinschaft. Wittel’s argument may inform our understanding of how commu-nicative patterns in rural communities are partly re-embedded through ongoing media transitions. But it must also be problematized. Relating Wittel’s discussion to Halfacree’s model of spatial coherence and Urry’s notion of network capital, as well as to findings from an ethnographic study in a Swedish countryside commu-nity, a more complex view is presented. It is argued that global communication networks under rural conditions contribute to the integration and sustainability of the community, as much as to processes of expansion and differentiation. The results show that network sociality and community constitute interdependent con-cepts. Through their capacity of linking people to external realms of interest, while simultaneously reinforcing their sense of belonging in the local community, online media promote ontological security at the individual level, thus operating as a social stabilizer.

  16. Full spatially coherent multiturn ERL x-ray source (MARS) based on two linacs

    Science.gov (United States)

    Getmanov, Ya V.; Kulipanov, G. N.; Shevchenko, O. A.; Skrinsky, A. N.; Tribendis, A. G.; Volkov, V. N.; Vinokurov, N. A.

    2013-03-01

    Multiturn energy recovery linacs (ERL) looks very promising for making ERLs less expensive and more flexible, but have serious intrinsic problems. Today, only one multiturn ERL exists. This Novosibirsk ERL operates with four orbit recuperation scheme. The conception of Multiturn Accelerator-recuperator Radiation Source (MARS) was proposed in 1997 by G.N. Kulipanov, A.N. Skrinsky and N.A. Vinokurov. The use of the two-linac ERL (D. Douglas, 2001) makes multiturn operation much easier. The feasibility study for such ERL-based high brightness x-ray source is presented.

  17. Parameter Diversity Induced Multiple Spatial Coherence Resonances and Spiral Waves in Neuronal Network with and Without Noise

    Institute of Scientific and Technical Information of China (English)

    李玉叶; 贾冰; 古华光; 安书成

    2012-01-01

    Diversity in the neurons and noise are inevitable in the real neuronal network.In this paper,parameter diversity induced spiral waves and multiple spatial coherence resonances in a two-dimensional neuronal network without or with noise are simulated.The relationship between the multiple resonances and the multiple transitions between patterns of spiral waves are identified.The coherence degrees induced by the diversity are suppressed when noise is introduced and noise density is increased.The results suggest that natural nervous system might profit from both parameter diversity and noise,provided a possible approach to control formation and transition of spiral wave by the cooperation between the diversity and noise.

  18. Evaluation of a semi-distributed model through an assessment of the spatial coherence of Intercatchment Groundwater Flows

    Science.gov (United States)

    de Lavenne, Alban; Thirel, Guillaume; Andréassian, Vazken; Perrin, Charles; Ramos, Maria-Helena

    2016-04-01

    Semi-distributed hydrological models aim to provide useful information to understand and manage the spatial distribution of water resources. However, their evaluation is often limited to independent and single evaluations at each sub-catchment within larger catchments. This enables to qualify model performance at different points, but does not provide a coherent assessment of the overall spatial consistency of the model. To cope with these methodological deficiencies, we propose a two-step strategy. First, we apply a sequential spatial calibration procedure to define spatially consistent model parameters. Secondly, we evaluate the hydrological simulations using variables that involve some dependency between sub-catchments to evaluate the overall coherence of model outputs. In this study, we particularly choose to look at the simulated Intercatchment Groundwater Flows (IGF). The idea is that the water that is lost in one place should be recovered somewhere else within the catchment to guarantee a spatially coherent water balance in time. The model used is a recently developed daily semi-distributed model, which is based on a spatial distribution of the lumped GR5J model. The model has five parameters for each sub-catchments and a streamflow velocity parameter for flow routing between them. It implements two reservoirs, one for production and one for routing, and estimates IGF according to the level of the second in a way that catchment can release water to IGF during high flows and receive water through IGF during low flows. The calibration of the model is performed from upstream to downstream, making an efficient use of spatially distributed streamflow measurements. To take model uncertainty into account, we implemented three variants of the original model structure, each one computing in a different way the IGF in each sub-catchment. The study is applied on over 1000 catchments in France. By exploring a wide area and a variability of hydrometeorological conditions

  19. Modeling of temporal and spatial coherency of net primary production (MODIS NPP) in the mountain forests of South Siberia

    Science.gov (United States)

    Ivanova, Yulia; Soukhovolsky, Vlad

    Net primary production (NPP) of mountain forest is very variable and depends on a variety of external modifying factors such as intensity and spectrum of solar radiation, climatic conditions in the area. Less studied are features of long-term NPP dynamics associated with self-regulation processes of tree growth in a forest. Mountain forests are a convenient object for analysis and modeling of long-term NPP changes that do not depend on climatic factors, since in mountain forests climatic conditions are uniquely determined by altitude Temporal and spatial coherence of mean annual NPP time series (Yrs. 2000 - 2012) was studied according to data from satellite observations of MODIS/TERRA. Mean annual NPP estimates' series were examined for different altitudinal zones in the Sayan Mountains (South of Central Siberia). Altitudes ranged from 600 to 1.800 meters above sea level. This area is lengthful vertically and has well-marked mountain-belt vegetation complexes, where mixed forests, fir and pine coniferous forests, alpine meadows and alpine tundra successively come one after another. Spatial and temporal coherence of NPP time series for different habitats is analyzed. The analysis showed that variations in annual NPP values of the fir (Abies sibirica) at different altitudes (450-1700 m) are synchronized. These variations in NPP values are described by the AR(2) model. Such behavior of studied NPP time series suggests a lag in growth of woody plants. In this case, the current NPP is influenced by the NPP values of the two previous years. At higher altitudes, where the density of the trees decreases and herbaceous plants become dominant, the range and synchronization of NPP variations decrease.

  20. Variability, Brightness Temperature, Superluminal Motion, Doppler Boosting, and Related Issues

    CERN Document Server

    Kellermann, K I

    2003-01-01

    We review the observations of rapid flux density variations in compact radio sources, and discuss the inverse Compton limit to the maximum brightness temperature of incoherent synchrotron sources in comparison with recent VLBA observations. The apparent agreement of the theoretical brightness temperature limit due to inverse Compton cooling and the brightness temperatures observed by early VLBI observations appears to have been fortuitous. VLBA observations have greatly improved the quality of the data, but many of the early issues remain unresolved.

  1. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millenium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  2. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  3. The contribution of z ≲ 6 sources to the spatial coherence in the unresolved cosmic near-infrared and X-ray backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Helgason, K.; Ricotti, M. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Cappelluti, N. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Hasinger, G. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Kashlinsky, A., E-mail: kari@astro.umd.edu [Observational Cosmology Laboratory, Code 665, NASA Goddard Space Flight Center, Greenbelt MD 20771 (United States)

    2014-04-10

    A spatial clustering signal has been established in Spitzer/IRAC measurements of the unresolved cosmic near-infrared background (CIB) out to large angular scales, ∼1°. This CIB signal, while significantly exceeding the contribution from the remaining known galaxies, was further found to be coherent at a highly statistically significant level with the unresolved soft cosmic X-ray background (CXB). This measurement probes the unresolved CXB to very faint source levels using deep near-IR source subtraction. We study contributions from extragalactic populations at low to intermediate redshifts to the measured positive cross-power signal of the CIB fluctuations with the CXB. We model the X-ray emission from active galactic nuclei (AGNs), normal galaxies, and hot gas residing in virialized structures, calculating their CXB contribution including their spatial coherence with all infrared emitting counterparts. We use a halo model framework to calculate the auto and cross-power spectra of the unresolved fluctuations based on the latest constraints of the halo occupation distribution and the biasing of AGNs, galaxies, and diffuse emission. At small angular scales (≲ 1'), the 4.5 μm versus 0.5-2 keV coherence can be explained by shot noise from galaxies and AGNs. However, at large angular scales (∼10'), we find that the net contribution from the modeled populations is only able to account for ∼3% of the measured CIB×CXB cross-power. The discrepancy suggests that the CIB×CXB signal originates from the same unknown source population producing the CIB clustering signal out to ∼1°.

  4. Short Pulse High Brightness X-ray Production with the PLEIADES Thomson Scattering Source

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Barty, C P J; Betts, S M; Brown, W J; Crane, J K; Cross, R R; Fittinghoff, D N; Gibson, D J; Hartemann, F V; Kuba, J; LaSage, G P; Rosenzweig, J B; Slaughter, D R; Springer, P T; Tremaine, A M

    2003-07-01

    We describe PLEIADES, a compact, tunable, high-brightness, ultra-short pulse, Thomson x-ray source. The peak brightness of the source is expected to exceed 10{sup 20} photons/s/0.1% bandwidth/mm{sup 2}/mrad{sup 2}. Initial results are reported and compared to theoretical calculations.

  5. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies. RESULTS: Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI. CONCLUSIONS: The data suggest that perceptions

  6. Compact Lumps

    CERN Document Server

    Bazeia, D; Menezes, R

    2015-01-01

    We study the presence of lumplike solutions in models described by a single real scalar field with standard kinematics in two-dimensional spacetime. The results show several distinct models that support the presence of bell-shaped, lumplike structures which may live in a compact space.

  7. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  8. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  9. Compact NMR

    Energy Technology Data Exchange (ETDEWEB)

    Bluemich, Bernhard; Haber-Pohlmeier, Sabina; Zia, Wasif [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie (ITMC)

    2014-06-01

    Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

  10. Compact NMR

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) spectroscopy is the most popular method for chemists to analyze molecular structures, while Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic tool for medical doctors that provides high-contrast images of biological tissue. In both applications, the sample (or patient) is positioned inside a large, superconducting magnet to magnetize the atomic nuclei. Interrogating radio-frequency pulses result in frequency spectra that provide the chemist with molecular information, the medical doctor with anatomic images, and materials scientist with NMR relaxation parameters. Recent advances in magnet technology have led to a variety of small permanent magnets to allow compact and low-cost instruments. The goal of this book is to provide an introduction to the practical use of compact NMR at a level nearly as basic as the operation of a smart phone.

  11. Low surface brightness galaxies

    Science.gov (United States)

    Vanderhulst, J. M.; Deblok, W. J. G.; Mcgaugh, S. S.; Bothun, G. D.

    1993-01-01

    A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotometry of H2 regions in LSB galaxies is underway. The goal is to verify the idea that LSB galaxies have low star formation rates because the local gas density falls below the critical density for star formation, and to study the stellar population and abundances in LSB galaxies. Such information should help understanding the evolutionary history of LSB galaxies. Some preliminary results are reported.

  12. Acceleration of Compact Radio Jets on Sub-parsec Scales

    CERN Document Server

    Lee, Sang-Sung; Krichbaum, Thomas P; Zensus, J Anton

    2016-01-01

    Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of the relativistic jets, and constrain models of jet formation in the inner jet region. We aim to observationally test such inner jet models. The very long baseline interferometry (VLBI) cores of compact radio sources are optically thick at a given frequency. The distance of the core from the central engine is inversely proportional to the frequency. Under the equipartition condition between the magnetic field energy and particle energy densities, the absolute distance of the VLBI core can be predicted. We compiled the brightness temperatures of VLBI cores at various radio frequencies of 2, 8, 15, and 86~GHz. We derive the brightness temperature on sub-parsec scales in the rest frame of the compact radio sources. We find that the brightness temperature increases with increasing distance from t...

  13. Fornax compact object survey FCOS: On the nature of Ultra Compact Dwarf galaxies

    CERN Document Server

    Mieske, S; Infante, L

    2004-01-01

    The results of the Fornax Compact Object Survey (FCOS) are presented. The FCOS aims at investigating the nature of the Ultra Compact Dwarf galaxies (UCDs) recently discovered in the center of the Fornax cluster (Drinkwater et al. 2000). 280 unresolved objects in the magnitude space covering UCDs and bright globular clusters (1820 mag) at 96% confidence. The mean velocity of the bright compact objects is consistent with that of the dwarf galaxy population in Fornax, but inconsistent with that of NGC 1399's globular cluster system at 93.5% confidence. The compact objects follow a colour magnitude relation with a slope very similar to that of normal dEs, but shifted about 0.2 mag redwards. The magnitude distribution of compact objects shows a fluent transition between UCDs and GCs with an overpopulation of 8 +/- 4 objects for V<20 mag with respect to the extrapolation of NGC 1399's GC luminosity function. The spatial distribution of bright compact objects is in comparison to the faint ones more extended at 88...

  14. Research on spatial coherence of undulator source in Shanghai synchrotron radiation facility%上海同步辐射装置波荡器光源空间相干性的研究

    Institute of Scientific and Technical Information of China (English)

    王华; 闫帅; 闫芬; 蒋升; 毛成文; 梁东旭; 杨科; 李爱国; 余笑寒

    2012-01-01

    利用高斯-谢尔光源模型理论与交叉谱密度函数在自由空间传输的规律,研究了上海同步辐射装置波荡器光源(BL15U)的空间相干性;讨论了预聚焦镜、单色器对光束空间相干性的影响;实验测量了单色光狭缝S2处光束的横向相干长度(Z方向).理论计算表明,S2处光束的横向相干长度为66.5μm,但实验测量结果为27μm.理论与实验相差较大的原因是由于S2上游光学元件预聚焦镜或单色器1期性高频振动导致了光束空间相干性的退化.实验结果表明,上海同步辐射装置波荡器光源已有较强的空间相干性,可以满足微米尺度的硬X射线相干性实验.%Firstly,based on the Gaussian-schell model source theory and the propagation of cross-spectral density function in free space, the spatial coherence of undulator source(BL15U) in Shanghai Synchrotron Radiation Facility is studied.Secondly,the influences of pre-focusing mirror and the monochromator on the beam spatial coherence are discussed.Finally,the spatial coherent length at mono slit S2 is measured.The spatial coherent length at S2 theoretically is 66.5μm,but experimentally is 27μm.This difference is due to the high frequency vibration of pre-focusing mirror or monochromato.Nevertheless,high coherent hard X ray beams can be obtained at the location of experimental sample and many coherent experiments can be fulfilled on this beamline.

  15. A Compact Wakefield Measurement Facility

    Science.gov (United States)

    Power, J. G.; Gai, W.

    2015-10-01

    The conceptual design of a compact, photoinjector-based, facility for high precision measurements of wakefields is presented. This work is motivated by the need for a thorough understanding of beam induced wakefield effects for any future linear collider. We propose to use a high brightness photoinjector to generate (approximately) a 2 nC, 2 mm-mrad drive beam at 20 MeV to excite wakefields and a second photoinjector to generate a 5 MeV, variably delayed, trailing witness beam to probe both the longitudinal and transverse wakefields in the structure under test. Initial estimates show that we can detect a minimum measurable dipole transverse wake function of 0.1 V/pC/m/mm and a minimum measurable monopole longitudinal wake function of 2.5 V/pC/m. Simulations results for the high brightness photoinjector, calculations of the facility's wakefield measurement resolution, and the facility layout are presented.

  16. 基于时空一致性的非结构化网格时变流场高效体绘制方法%High-Efficiency Volume Rendering of Unstructured-Grid Time-Varying Flows Using Temporal and Spatial Coherence

    Institute of Scientific and Technical Information of China (English)

    马千里; 刘涛; 王攀; 刘瑜; 李思昆

    2011-01-01

    The temporal and spatial coherence which is an important characteristic of unsteady flows plays an essential role in visualizing time-varying fields. This paper presents an approach for high- efficiency volume rendering of unstructured time-varying flows using the temporal and spatial coherence on the framework of the hardware-based ray casting algorithm (HRC). Firstly, a method is provided to analyze the temporal coherence of both the cell and the vertex data on unstructured grids. Then the cell and the vertex data temporal tables are built to achieve a lower time cost during rendering. Secondly, a novel texture structure is designed to separate the vertex data from the cell data, and a smart gradient matrix is used to reduce the pressure of GPU memory. The scheme of data management can effectively avoid rendering stalls and lead to a compact and efficient storage. The experiments demonstrate that our approach not only gains a much higher efficiency than the existing method, but also achieves a lower space cost, allowing rendering time-varying data on a larger mesh scale.%时空一致性是时变流场的重要性质,也是加速时变数据可视化算法的关键.以硬件加速的光线投射算法(HRC)为框架,设计并实现了一种基于时空一致性的非结构化网格时变流场高效体绘制方法.首先提出一种分析非结构化网格单元和顶点数据时间一致性的方法,分别建立单元和顶点数据时间表,以降低绘制过程中的计算开销;然后设计一种单元和顶点数据相分离的GPU纹理结构,并采用一种小巧的单元梯度矩阵来降低显存开销;同时,设计了一种合理的数据调度策略,既能有效地避免绘制停顿,又使显存纹理结构更为紧致、高效.实验结果表明,该方法不仅明显地提高了绘制效率,而且具有更优显存空间利用率,能实现更大网格规模的非结构化网格时变流场数据体绘制.

  17. Compact Reactor

    International Nuclear Information System (INIS)

    Weyl's Gauge Principle of 1929 has been used to establish Weyl's Quantum Principle (WQP) that requires that the Weyl scale factor should be unity. It has been shown that the WQP requires the following: quantum mechanics must be used to determine system states; the electrostatic potential must be non-singular and quantified; interactions between particles with different electric charges (i.e. electron and proton) do not obey Newton's Third Law at sub-nuclear separations, and nuclear particles may be much different than expected using the standard model. The above WQP requirements lead to a potential fusion reactor wherein deuterium nuclei are preferentially fused into helium nuclei. Because the deuterium nuclei are preferentially fused into helium nuclei at temperatures and energies lower than specified by the standard model there is no harmful radiation as a byproduct of this fusion process. Therefore, a reactor using this reaction does not need any shielding to contain such radiation. The energy released from each reaction and the absence of shielding makes the deuterium-plus-deuterium-to-helium (DDH) reactor very compact when compared to other reactors, both fission and fusion types. Moreover, the potential energy output per reactor weight and the absence of harmful radiation makes the DDH reactor an ideal candidate for space power. The logic is summarized by which the WQP requires the above conditions that make the prediction of DDH possible. The details of the DDH reaction will be presented along with the specifics of why the DDH reactor may be made to cause two deuterium nuclei to preferentially fuse to a helium nucleus. The presentation will also indicate the calculations needed to predict the reactor temperature as a function of fuel loading, reactor size, and desired output and will include the progress achieved to date

  18. 孪生光束干涉法测量光源的空间相干性%Measurement of the spatial coherence of extended light source by twin beams-interference method

    Institute of Scientific and Technical Information of China (English)

    满天龙; 万玉红; 江竹青; 王大勇; 陶世荃

    2013-01-01

    The coherence of light source have been employed in many aspects, such as optical processing and optical coherence holography. For this reason it has attracted vast interest in developing quantitative methods for measuring the spatial coherence characteristics of an optical field. We propose a novel method for measuring the spatial coherence degree of optical fields based on the triangular interferometer. Spatially separated twin beams are formed by an interferometer, and the interferogram formed by the twin beams is captured by an image detector. Because the separation of the twin beams is related to the coordinate position of the input beam, a series of positions are sampled by moving a pinhole and corresponding interference patterns are recorded. Then the visibilities of the interference patterns are calculated for measuring the spatial coherence degree. Experimentally measured and theoretically calculated values of spatial coherence degree fit well. The measurement error is 3.8%. Experimental results show the method proposed here is effective, simple, and robust without any special optical elements.%定量测定光源空间相干性在部分相干光成像,非相干全息术及光信息处理领域具有重要的研究价值.本文基于三角全息干涉光路提出了一种测量光源空间相干性的新方法.利用三角干涉全息光路系统中分束镜产生的孪生光束进行干涉获得干涉图,通过调整光源中心位置在写入平面内偏离光轴的量,改变两孪生光束空间分离量的大小,采集对应的一系列干涉图,计算干涉图样的对比度,从而对光源照明空间的波前上一系列不同距离的点对之间的空间复相干度进行测量.实验系统光路配置较为简单且不需要使用特殊加工的光学元件.针对一个准单色的扩展光源设计并进行实验,结果表明利用文中提出的方法可以准确的测量光源的空间相干性,实验结果相对于理

  19. Acceleration of Compact Radio Jets on Sub-parsec Scales

    OpenAIRE

    Lee, Sang-Sung; Lobanov, Andrei P.; Krichbaum, Thomas P.; Zensus, J. Anton

    2016-01-01

    Jets of compact radio sources are highly relativistic and Doppler boosted, making studies of their intrinsic properties difficult. Observed brightness temperatures can be used to study the intrinsic physical properties of the relativistic jets, and constrain models of jet formation in the inner jet region. We aim to observationally test such inner jet models. The very long baseline interferometry (VLBI) cores of compact radio sources are optically thick at a given frequency. The distance of t...

  20. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  1. Interferometric measurement of the beam size in the compact storage ring

    CERN Document Server

    Yamamoto, Y; Mitsuhashi, T; Amano, D; Iwasaki, H

    2001-01-01

    The beam size in the compact superconducting storage ring AURORA at Ritsumeikan University was measured using the SR-interferometer. The radiation beam from the bending magnet was passed through the double-slit and an interferogram formed in the visible spectral region was recorded using a CCD camera. The spatial coherence of the beam was derived from the analysis of the intensity profile and its dependence on the spatial frequency has yielded the beam size of 10.5 mu m in the vertical direction. It is unexpectedly small, indicating a high accuracy in the design of magnetic field in the magnet. The beam size could be varied by applying an rf kick electric field and the dependence of the beam lifetime on the size has shown that it is primarily governed by the Tauschek effect.

  2. The EUVE bright source list

    Science.gov (United States)

    Stroozas, B.; Mcdonald, K.; Antia, B.; Mcdonald, J.; Wiercigroch, A.

    1993-01-01

    Initial results for bright extreme ultraviolet sources discovered during the EUVE all-sky and deep ecliptic surveys have been published as a Bright Source List (BSL) and released to the astronomical community with a recent NASA research announcement (NRA 93-OSS-02, Appendix F). This paper describes the data processing software, the EUVE survey data set, and the production of the BSL at the Center for EUV Astrophysics. The contents, format, and selection criteria for sources, the data processing strategy, some problems encountered, and a summary of the BSL results are presented.

  3. All things bright and beautiful

    OpenAIRE

    Brown, Chloe

    2012-01-01

    'All Things Bright and Beautiful' was exhibited in 20/21 Visual Arts Centre, Scunthorpe, which is sited in a 'redundant' church. The fundamental question that the exhibition explored concerned the role of 'the animal' within contemporary art and within secular society, which in turn hoped to prompt reflections on our understanding of the place of 'the human' in the world and in nature. If there is no divine order, as posited by the hymn 'All Things Bright and Beautiful', where does this leave...

  4. Compact radio cores : from the first black holes to the last

    NARCIS (Netherlands)

    Falcke, H; Kording, E; Nagar, NM

    2004-01-01

    One of the clearest signs of black hole activity is the presence of a compact radio core in the nuclei of galaxies. While in the past the focus had been on the few bright and relativistically beamed sources, new surveys now show that essentially all black holes produce compact radio emission that ca

  5. Bright Transients discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Six bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  6. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  7. GPM Intercalibrated Radiometer Brightness Temperatures

    Science.gov (United States)

    Stocker, Erich Franz; Chou, Joyce

    2013-04-01

    One of the keys to consistent precipitation retrieval from passive microwave radiometer measurements (whether imagers or sounders) is accurate, long-term consistent brightness temperature retrievals. This becomes doubly important when there measurements are taken from radiometers on multiple platforms, from multiple agencies, with many different purposes. The Global Precipitation Measurement (GPM) mission addresses this issue directly with the production of intercalibrated brightness temperatures from all the partner satellites contributing to the GPM mission. These intercalibrated brightness temperatures are given the product designation: 1C within GPM. This paper will describe the GPM approach to intercalibration 1C products. The intercalibration and creation of the products uses a 5-step methodology: comparison of the partner standard products (either Tb or Ta) with the GPM reference standard; determination of adjustments that should be made to each product to create consistent brightness temperatures; re-orbitization of all orbits (in non-realtime) to be in the standard GPM south-south orbit; application of the adjustments to the partner provide 1B(or 1A) products; production of 1C products in HDF5 using a "standard" logical format for any radiometer regardless of its 1B format. This paper describes each of these steps and provides the background for them. It discusses in some detail the current 1C logical format and why this format facilitates use by downstream product algorithms and end-users. Most importantly it provides the analysis approach established by the GPM inter-calibration working group in establishing the adjustments to be made at the 1C level. Finally, using DMSP F16-18, it provides examples of the 1C products and discusses the adjustments that are made.

  8. Bright solitons from defocusing nonlinearities

    OpenAIRE

    Borovkova, Olga V.; Kartashov, Yaroslav; Torner Sabata, Lluís; Malomed, Boris A.

    2011-01-01

    We report that defocusing cubic media with spatially inhomogeneous nonlinearity, whose strength increases rapidly enough toward the periphery, can support stable bright localized modes. Such nonlinearity landscapes give rise to a variety of stable solitons in all three dimensions, including one-dimensional fundamental and multihump states, two-dimensional vortex solitons with arbitrarily high topological charges, and fundamental solitons in three dimensions. Solitons maintain their coherence ...

  9. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  10. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  11. Star formation suppression in compact group galaxies

    DEFF Research Database (Denmark)

    Alatalo, K.; Appleton, P. N.; Lisenfeld, U.;

    2015-01-01

    We present CO(1-0) maps of 12 warm H-2-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H2 bright galaxies, with the Combined Array for Research in Millimeter Astronomy. We found a variety of molecular gas distributions within the HCGs, including regularly rotating disks......, bars, rings, tidal tails, and possibly nuclear outflows, though the molecular gas morphologies are more consistent with spirals and earlytype galaxies than mergers and interacting systems. Our CO-imaged HCG galaxies, when plotted on the Kennicutt-Schmidt relation, shows star formation (SF) suppression...

  12. Self-Compacting Concrete

    OpenAIRE

    Okamura, Hajime; OUCHI, Masahiro

    2003-01-01

    Self-compacting concrete was first developed in 1988 to achieve durable concrete structures. Since then, various investigations have been carried out and this type of concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making self-compacting concrete a standard concrete.

  13. Mechanics of tissue compaction.

    Science.gov (United States)

    Turlier, Hervé; Maître, Jean-Léon

    2015-12-01

    During embryonic development, tissues deform by a succession and combination of morphogenetic processes. Tissue compaction is the morphogenetic process by which a tissue adopts a tighter structure. Recent studies characterized the respective roles of cells' adhesive and contractile properties in tissue compaction. In this review, we formalize the mechanical and molecular principles of tissue compaction and we analyze through the prism of this framework several morphogenetic events: the compaction of the early mouse embryo, the formation of the fly retina, the segmentation of somites and the separation of germ layers during gastrulation.

  14. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  15. High brightness beams and applications

    International Nuclear Information System (INIS)

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

  16. Compact radio cores in radio-quiet AGNs

    CERN Document Server

    Maini, Alessandro; Norris, Ray P; Giovannini, Gabriele; Spitler, Lee R

    2016-01-01

    The mechanism of radio emission in radio-quiet (RQ) active galactic nuclei (AGN) is still debated and might arise from the central AGN, from star formation activity in the host, or from either of these sources. A direct detection of compact and bright radio cores embedded in sources that are classified as RQ can unambiguously determine whether a central AGN significantly contributes to the radio emission. We search for compact, high-surface-brightness radio cores in RQ AGNs that are caused unambiguously by AGN activity. We used the Australian Long Baseline Array to search for compact radio cores in four RQ AGNs located in the Extended Chandra Deep Field South (ECDFS). We also targeted four radio-loud (RL) AGNs as a control sample. We detected compact and bright radio cores in two AGNs that are classified as RQ and in one that is classified as RL. Two RL AGNs were not imaged because the quality of the observations was too poor. We report on a first direct evidence of radio cores in RQ AGNs at cosmological reds...

  17. Spatial-Coherence Effects in Spectroscopy

    Science.gov (United States)

    Wolf, Emil

    2002-12-01

    In this report account is presented of research carried out during the period December 1, 1999 - November 30, 2002 under the sponsorship of the Air Force Office of Scientific Research under grant F49620-00l-l-0125. Our research covered many areas of modern optical physics, especially wave propagation in random media, inverse scattering, coherence properties of light, correlation-induced spectral changes, partially coherent beams, focusing of waves of arbitrary state of coherence, partially coherent solitons, spreading of partially coherent beams in random media, diffraction tomography and singular optics with polychromatic light. We believe that of special significance are some new results that we have obtained concerning the propagation of partially coherent beams in the turbulent atmosphere. The results indicate that in certain situations it is preferable to employ partially coherent beams rather than fully coherent ones for communication, tracking and guiding, for example. These results are preliminary and we are pursuing the subject further. In the field of singular optics we have opened up a new direction for progress in the field by having shown that some new and unexpected effects take place in the neighborhood of phase singularities in optical fields, when the light is polychromatic rather than monochromatic (studied previously). Specifically we have demonstrated that drastic changes of the spectrum of light take place in the immediate vicinity of the singular points. The results of our investigations were reported in 43 publications. They are listed on pages 3 to 5. Summaries of these publications are given on pages 6 - 14. Scientists who have participated in this research are listed on page 15.

  18. The Bright New Financial System

    Directory of Open Access Journals (Sweden)

    Associate Professor Adela Coman

    2009-05-01

    Full Text Available By the end of 2008, Mr. Paul Volcker gave financiers a devastating critique. “For all its talented participants, for all its rich rewards” he said, the “bright new financial system” has “failed the test of the marketplace”.In light of the events of recent weeks, it is hard to disagree. A financial system that ends up with the government taking over some of its biggest institutions in serial weekend rescues and which requires the promise of 700 billion dollars in public money to stave off catastrophe is not a trustworthy system. The disappearance of all five big American investment banks – either by bankruptcy or rebirth as commercial banks – is powerful evidence that Wall Street failed “the test of the marketplace”. Something went wrong.But what exactly and why? A more serious analysis needs to distinguish between three separate questions: what is Mr. Volcker’s “bright new financial system”? Second, how far was today’s mess created by instabilities that are inseparable from modern finance and how far was it fuelled by other errors and distortions? Third, to the extent that modern finance does bear the blame, what is the balance between its costs and its benefits and how can it be improved?

  19. Compaction properties of isomalt

    NARCIS (Netherlands)

    Bolhuis, Gerad K.; Engelhart, Jeffrey J. P.; Eissens, Anko C.

    2009-01-01

    Although other polyols have been described extensively as filler-binders in direct compaction of tablets, the polyol isomalt is rather unknown as pharmaceutical excipient, in spite of its description in all the main pharmacopoeias. In this paper the compaction properties of different types of ispoma

  20. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  1. [Bright light therapy for elderly].

    Science.gov (United States)

    Okawa, Masako

    2015-06-01

    Bright light therapy (BLT) holds considerable promise for sleep problems in the elderly. BLT for community-dwelling patients with Alzheimer's disease showed significant improvement in sleep parameters. In the institutional setting, BLT was effective in reducing daytime nap duration. Morning BLT was found to advance the peak circadian rhythm and increase activity level in daytime and melatonin level at night. Light therapy could be used in combination with other nonpharmacological methods such as social activities, outside walking, physical exercises, which showed greater effects than independent BLT on sleep and cognitive function. BLT treatment strategy was proposed in the present paper. We should pay more attentions to BLT in community setting for mental and physical well-being. PMID:26065132

  2. Ultra-Compact Dwarfs around NGC 3268

    CERN Document Server

    Caso, Juan Pablo; Richtler, Tom; Calderón, Juan Pablo; Castelli, Analía V Smith

    2014-01-01

    We present radial velocities (from Gemini/GMOS) of the second sample of ultra-compact dwarfs (UCDs) and bright globular clusters (GCs) in the Antlia cluster. Twenty-three objects are located around the giant elliptical NGC 3268, and one is close to the fainter lenticular NGC 3273. Together with previously found UCDs around NGC 3258 a total of 35 UCDs and bright GCs has been now identified in the Antlia cluster. Their colours and magnitudes are compared with those of the nuclei of dE,N galaxies already confirmed as Antlia members. For a subsample that lie on ACS images and are brighter than M_V = -9 mag, the effective radii (R_eff) have been measured, the maximum radius being approximately 10 pc. In addition to the radial velocity sample, we find 10 objects in the magnitude range corresponding to GCs but with 10 < R_eff < 17 pc, resembling the so-called `extended clusters'. By number and magnitude, the new UCDs fit to the GC luminosity function, supporting their interpretation as bright GCs. Additionally...

  3. Small Valdivia compact spaces

    CERN Document Server

    Kubi's, W; Kubi\\'s, Wieslaw; Michalewski, Henryk

    2005-01-01

    We prove a preservation theorem for the class of Valdivia compact spaces, which involves inverse sequences of ``simple'' retractions. Consequently, a compact space of weight $\\loe\\aleph_1$ is Valdivia compact iff it is the limit of an inverse sequence of metric compacta whose bonding maps are retractions. As a corollary, we show that the class of Valdivia compacta of weight at most $\\aleph_1$ is preserved both under retractions and under open 0-dimensional images. Finally, we characterize the class of all Valdivia compacta in the language of category theory, which implies that this class is preserved under all continuous weight preserving functors.

  4. Compact boson stars

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Betti [School of Engineering and Science, Jacobs University, Postfach 750 561, D-28725 Bremen (Germany); Kleihaus, Burkhard; Kunz, Jutta [Institut fuer Physik, Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Schaffer, Isabell, E-mail: i.schaffer@jacobs-university.de [School of Engineering and Science, Jacobs University, Postfach 750 561, D-28725 Bremen (Germany)

    2012-07-24

    We consider compact boson stars that arise for a V-shaped scalar field potential. They represent a one parameter family of solutions of the scaled Einstein-Gordon equations. We analyze the physical properties of these solutions and determine their domain of existence. Along their physically relevant branch emerging from the compact Q-ball solution, their mass increases with increasing radius. Employing arguments from catastrophe theory we argue that this branch is stable, until the maximal value of the mass is reached. There the mass and size are on the order of magnitude of the Schwarzschild limit, and thus the spiraling respectively oscillating behaviour, well known for compact stars, sets in.

  5. Quantum communication with macroscopically bright nonclassical states.

    Science.gov (United States)

    Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim

    2015-11-30

    We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light. PMID:26698776

  6. Roller compaction of theophylline

    OpenAIRE

    Hadzovic, Ervina

    2008-01-01

    1. Summary Direct compaction requires a very good flowability and compressibility of the materials. Those parameters become even more critical if the formulation contains large amount of active substance. To overcome these problems, several alternatives have been used. Roller compaction is a very attractive technology in the pharmaceutical industry. It is a fast and efficient way of producing granules, especially suitable for moisture sensitive materials. The intention of this work was to ...

  7. Soliton fay identities: II. Bright soliton case

    International Nuclear Information System (INIS)

    We present a set of bilinear matrix identities that generalize the ones that have been used to construct the bright soliton solutions for various models. As an example of an application of these identities, we present a simple derivation of the N-bright soliton solutions for the Ablowitz–Ladik hierarchy. (paper)

  8. Spatial Brightness Perception of Trichromatic Stimuli

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

    An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is not predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.

  9. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies. Th

  10. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  11. Incoherently coupled dark-bright photorefractive solitons

    Science.gov (United States)

    Chen, Zhigang; Segev, Mordechai; Coskun, Tamer H.; Christodoulides, Demetrios N.; Kivshar, Yuri S.; Afanasjev, Vsevolod V.

    1996-11-01

    We report the observation of incoherently coupled dark-bright spatial soliton pairs in a biased bulk photorefractive crystal. When such a pair is decoupled, the dark component evolves into a triplet structure, whereas the bright one decays into a self-defocusing beam.

  12. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  13. Compact groups in theory and practice - I. The spatial properties of compact groups

    CERN Document Server

    McConnachie, Alan W; Patton, David R

    2008-01-01

    We use a mock galaxy catalogue based upon the Millennium Run simulation to investigate the intrinsic spatial properties of compact groups of galaxies. We find that approximately 30% of galaxy associations identified in our mock catalogue are physically dense systems of four or more galaxies with no interlopers, approximately half are close associations of 2, 3 or 4 galaxies with one or more interlopers, and the remainder are not physically dense. Genuine compact groups are preferentially brighter and more isolated than those with interlopers; by increasing the required minimum surface brightness of a group from the canonical value of 26mags/arcsec^2 to 22mags/arcsec^2, we can increase the proportion of genuinely compact systems identified with no interlopers from 29% to 75%. Of the genuine compact groups identified, more than half consist of a single dark matter halo with all the member galaxies deeply embedded within it. In some cases, there are other galaxies which share the same halo (typically with mass ~...

  14. A bright neutron source driven by relativistic transparency of solids

    Science.gov (United States)

    Roth, M.; Jung, D.; Falk, K.; Guler, N.; Deppert, O.; Devlin, M.; Favalli, A.; Fernandez, J.; Gautier, D. C.; Geissel, M.; Haight, R.; Hamilton, C. E.; Hegelich, B. M.; Johnson, R. P.; Kleinschmidt, A.; Merrill, F.; Schaumann, G.; Schoenberg, K.; Schollmeier, M.; Shimada, T.; Taddeucci, T.; Tybo, J. L.; Wagner, F.; Wender, S. A.; Wilde, C. H.; Wurden, G. A.

    2016-03-01

    Neutrons are a unique tool to alter and diagnose material properties and excite nuclear reactions with a large field of applications. It has been stated over the last years, that there is a growing need for intense, pulsed neutron sources, either fast or moderated neutrons for the scientific community. Accelerator based spallation sources provide unprecedented neutron fluxes, but could be complemented by novel sources with higher peak brightness that are more compact. Lasers offer the prospect of generating a very compact neutron source of high peak brightness that could be linked to other facilities more easily. We present experimental results on the first short pulse laser driven neutron source powerful enough for applications in radiography. For the first time an acceleration mechanism (BOA) based on the concept of relativistic transparency has been used to generate neutrons. This mechanism not only provides much higher particle energies, but also accelerated the entire target volume, thereby circumventing the need for complicated target treatment and no longer limited to protons as an intense ion source. As a consequence we have demonstrated a new record in laser-neutron production, not only in numbers, but also in energy and directionality based on an intense deuteron beam. The beam contained, for the first time, neutrons with energies in excess of 100 MeV and showed pronounced directionality, which makes then extremely useful for a variety of applications. The results also address a larger community as it paves the way to use short pulse lasers as a neutron source. They can open up neutron research to a broad academic community including material science, biology, medicine and high energy density physics as laser systems become more easily available to universities and therefore can complement large scale facilities like reactors or particle accelerators. We believe that this has the potential to increase the user community for neutron research largely.

  15. Compact radio sources in luminous infrared galaxies

    Science.gov (United States)

    Parra, Rodrigo

    2007-08-01

    Radio interferometry is an observational technique of high sensitivity and incomparably high spatial resolution. Moreover, because radio waves can freely propagate through interstellar dust and gas, it allows the study of regions of the universe completely obscured at other wavelengths. This thesis reports the observational and theoretical results of my research during the past four years which are mostly based on interferometric radio data. The COLA sample is an infrared selected sample of active star forming galaxies. We conducted 6 cm VLA and VLBI snapshot observations of the northern half of this sample. The radio emission seen at VLA scales is consistent with being powered by star formation activity because it follows the far infrared to radio correlation. We detect 22% of the sample sources in our VLBI snapshots. Based on luminosity arguments, we argue that these sub-parsec VLBI sources are powered by AGN activity. Furthermore, we find that VLBI detections are preferentially found in sources whose VLA scale structures have the highest peak brightnesses suggesting a strong correlation between compact starburst and AGN activity. This observational result is consistent with the theoretical picture of an Eddington-limited nuclear starburst acting as the last valve in the pipeline transporting the gas from kiloparsec scales onto the accretion disc of a buried AGN. Arp 220 is the archetypical ultra luminous infrared galaxy. For many years this source has been known to harbour a compact (~100 pc) cluster of unresolved 18 cm bright sources believed to be bright core collapse supernovae. Using multiwavelength VLBI observations, we obtained for the first time radio spectra for 18 of these sources. We find that over a half of them have spectra consistent with young supernovae. The rest can be better explained as older supernova remnants interacting with the high density starburst ISM. This finding allowed us to constrain the number of possible scenarios for the Arp 220

  16. Focused ion beams using a high-brightness plasma source

    Science.gov (United States)

    Guharay, Samar

    2002-10-01

    High-brightness ion beams, with low energy spread, have merits for many new applications in microelectronics, materials science, and biology. Negative ions are especially attractive for the applications that involve beam-solid interactions. When negative ions strike a surface, especially an electrically isolated surface, the surface charging voltage is limited to few volts [1]. This property can be effectively utilized to circumvent problems due to surface charging, such as device damage and beam defocusing. A compact plasma source, with the capability to deliver either positive or negative ion beams, has been developed. H- beams from this pulsed source showed brightness within an order of magnitude of the value for beams from liquid-metal ion sources. The beam angular intensity is > 40 mAsr-1 and the corresponding energy spread is 1 Acm-2 and a spot size of 100 nm. Such characteristics of focused beam parameters, using a dc source, will immediately open up a large area of new applications. [1] P. N. Guzdar, A. S. Sharma, S. K. Guharay, "Charging of substrates irradiated by particle beams" Appl. Phys. Lett. 71, 3302 (1997). [2] S. K. Guharay, E. Sokolovsky, J. Orloff, "Characteristics of ion beams from a Penning source for focused ion beam applications" J. Vac. Sci Technol. B17, 2779 (1999).

  17. Surface Brightness Profiles of Dwarf Galaxies: I. Profiles and Statistics

    CERN Document Server

    Herrmann, Kimberly A; Elmegreen, Bruce G

    2013-01-01

    Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs are flat or increasing out to a break before falling off. Here we re-examine the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single, double, or even triple exponential profiles in up to 11 passbands: GALEX FUV and NUV, ground-based UBV JHK and H{\\alpha}, and Spitzer 3.6 and 4.5 {\\mu}m. We find that more luminous galaxies have brighter centers, larger inner and outer scale lengths, and break at larger radii; dwarf trends with M_B extend to spirals. However, the V-band break surface brightness is independent of break type, M_B, and Hubble type. Dwarf Type II and III profiles fall off similarly beyond the breaks but have diff...

  18. Compactness theorems of fuzzy semantics

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The relationship among diverse fuzzy semantics vs. the corresponding logic consequence operators has been analyzed systematically. The results that compactness and logical compactness of fuzzy semantics are equivalent to compactness and continuity of the logic consequence operator induced by the semantics respectively have been proved under certain conditions. A general compactness theorem of fuzzy semantics have been established which says that every fuzzy semantics defined on a free algebra with members corresponding to continuous functions is compact.

  19. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  20. Designers predict a bright future

    International Nuclear Information System (INIS)

    As power plant designers and builders, there is a bright future for the industry. The demand for electricity will continue to grow, and the need for new plants will increase accordingly. But companies that develop and supply these plants must adapt to new ways of doing business if they expect to see the dawn of this new age. Several factors will have a profound effect on the generation and use of electricity in future years. Instant communications now reach all corners of the globe, making people everywhere aspire to a higher standard of living. The economic surge needed to satisfy these appetites will, in turn, be fed by a network of suppliers who are themselves restructuring to serve global markets, unimpeded by past nationalistic barriers to trade. The strong correlation between economic progress and the growing demand for electricity is well recognized. A ready supply of affordable electricity is a necessary underpinning for any economic expansion. As economies advance and jobs increase, electric demand grows geometrically, fueled by an ever-improving quality of life. Coupled with increasing demand is the worldwide trend toward privatization of the generation industry. The reasons may vary in different parts of the world, but the effect is the same--companies are battling intensely for the right to build or purchase generating facilities. Those companies, like the industry they serve, are themselves in a period of transition. Once a closed, monopolistic group of owners in a predominantly services-based market, they are, thanks to competitive forces, being driven steadily toward a product-based structure

  1. Compact Dynamical Foliations

    CERN Document Server

    Carrasco, Pablo D

    2011-01-01

    According to the work of Dennis Sullivan, there exists a smooth flow on the 5-sphere all of whose orbits are periodic although there is no uniform bound on their periods. The question addressed in this article is whether such an example can occur in the partially hyperbolic context. That is, does there exist a partially hyperbolic diffeomorphism of a compact manifold such that all the leaves of its center foliation are compact although there is no uniform bound for their volumes. We will show that the previous question has negative answer under very natural hypothesis as one-dimensional center foliation, transitivity or in the volume preserving case. Moreover we study the dynamical properties of partially hyperbolic maps preserving a compact center foliation. We prove in particular that if the number of center leaves with non-trivial holonomy is finite then the map is plaque expansive.

  2. An Ultraviolet imager to study bright UV sources

    CERN Document Server

    Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A G; Safonova, Margarita; Murthy, Jayant

    2016-01-01

    We have designed and developed a compact ultraviolet imaging payload to fly on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and e...

  3. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    Energy Technology Data Exchange (ETDEWEB)

    Chesny, D. L.; Oluseyi, H. M. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Orange, N. B. [OrangeWave Innovative Science, LLC, Moncks Corner, SC 29461 (United States); Champey, P. R. [Department of Optical Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  4. An Active Black Hole in a Compact Dwarf

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    A new type of galaxy has just been added to the galaxy zoo: a small, compact, and old elliptical galaxy that shows signs of a monster black hole actively accreting material in its center. What can this unusual discovery tell us about how compact elliptical galaxies form?A New Galactic BeastCompact elliptical galaxies are an extremely rare early-type dwarf galaxy. Consistent with their name, compact ellipticals are small, very compact collections of ancient stars; these galaxies exhibit a high surface brightness and arent actively forming stars.Optical view of the ancient compact elliptical galaxy SDSS J085431.18+173730.5 (center of image) in an SDSS color composite image. [Adapted from Paudel et al. 2016]Most compact ellipticals are found in dense environments, particularly around massive galaxies. This has led astronomers to believe that compact ellipticals might form via the tidal stripping of a once-large galaxy in interactions with another, massive galaxy. In this model, once the original galaxys outer layers are stripped away, the compact inner bulge component would be left behind as a compact elliptical galaxy. Recent discoveries of a few isolated compact ellipticals, however, have strained this model.Now a new galaxy has been found to confuse our classification schemes: the first-ever compact elliptical to also display signs of an active galactic nucleus. Led by Sanjaya Paudel (Korea Astronomy and Space Science Institute), a team of scientists discovered SDSS J085431.18+173730.5 serendipitously in Sloan Digital Sky Survey data. The team used SDSS images and spectroscopy in combination with data from the Canada-France-Hawaii Telescope to learn more about this unique galaxy.Puzzling CharacteristicsSDSS J085431.18+173730.5 presents an interesting conundrum. Ancient compact ellipticals are supposed to be devoid of gas, with no fuel left to trigger nuclear activity. Yet SDSS J085431.18+173730.5 clearly shows the emission lines that indicate active accretion onto

  5. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  6. The structure of bright zinc coatings

    Directory of Open Access Journals (Sweden)

    MIODRAG STOJANOVIC

    2000-11-01

    Full Text Available The structures of bright zinc coatings obtained from acid sulfate solutions in the presence of dextrin/salicyl aldehyde mixture were examined. It was shown by the STM technique that the surfaces of bright zinc coatings are covered by hexagonal zinc crystals, the tops of planes of which are flat and mutually parallel and which exhibit smoothness on the atomic level. X-Ray diffraction (XRD analysis of the bright zinc coatings showed that the zinc crystallites are oriented in the (110 plane only.

  7. Tachyons in Compact Spaces

    CERN Document Server

    Suyama, T

    2005-01-01

    We discuss condensations of closed string tachyons localized in compact spaces. Time evolution of an on-shell condensation is naturally related to the worldsheet RG flow. Some explicit tachyonic compactifications of Type II string theory is considered, and some of them are shown to decay into supersymmetric theories known as the little string theories.

  8. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  9. The solar brightness temperature at millimeter wavelengths

    Science.gov (United States)

    Kuseski, R. A.; Swanson, P. N.

    1976-01-01

    Measurements of the brightness temperature of the sun near 36 GHz and 93 GHz were made using the new moon as a calibration source. Provided the brightness temperature of the moon is known and all measurements are reduced to the same zenith angle, a simple expression can be used for the sun-to-new moon ratio which is independent of antenna gain, atmospheric absorption and reemission, and radiometer calibration constants. This ratio was measured near 36 GHz and at two frequencies near 93 GHz with a Dicke switched superheterodyne radiometer system and a 2.4 m Cassegrain antenna. The slopes of the solar brightness temperature spectrum based on these ratios were measured. The absolute solar brightness spectrum derived from all current available measurements supplemented by the present ones is also plotted and discussed.

  10. A spectroscopic atlas of bright stars

    CERN Document Server

    Martin, Jack

    2009-01-01

    Suitable for amateur astronomers interested in practical spectroscopy or spectrography, this reference book identifies more than 70 (northern hemisphere) bright stars that are suitable observational targets. It provides finder charts for locating these sometimes-familiar stars.

  11. Development of a high brightness ion source

    International Nuclear Information System (INIS)

    The brightness and emittance of an ion beam can depend on the ion temperature, aberrations and scattering, as well as other factors. However, it is the ion temperature which determines the irreducible minimum value of the emittance and hence brightness, as the other components can be eliminated by careful design. An ion source design is presented which has attained this minimum value for the emittance; the dependence of the ion temperature on the plasma source parameters is discussed

  12. Observations and diagnostics in high brightness beams

    Science.gov (United States)

    Cianchi, A.; Anania, M. P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V.

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  13. Energy-exchange collisions of dark-bright-bright vector solitons.

    Science.gov (United States)

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices. PMID:26764780

  14. Energy-exchange collisions of dark-bright-bright vector solitons

    Science.gov (United States)

    Radhakrishnan, R.; Manikandan, N.; Aravinthan, K.

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  15. Optimal design of compact and connected nature reserves for multiple species.

    Science.gov (United States)

    Wang, Yicheng; Önal, Hayri

    2016-04-01

    When designing a conservation reserve system for multiple species, spatial attributes of the reserves must be taken into account at species level. The existing optimal reserve design literature considers either one spatial attribute or when multiple attributes are considered the analysis is restricted only to one species. We built a linear integer programing model that incorporates compactness and connectivity of the landscape reserved for multiple species. The model identifies multiple reserves that each serve a subset of target species with a specified coverage probability threshold to ensure the species' long-term survival in the reserve, and each target species is covered (protected) with another probability threshold at the reserve system level. We modeled compactness by minimizing the total distance between selected sites and central sites, and we modeled connectivity of a selected site to its designated central site by selecting at least one of its adjacent sites that has a nearer distance to the central site. We considered structural distance and functional distances that incorporated site quality between sites. We tested the model using randomly generated data on 2 species, one ground species that required structural connectivity and the other an avian species that required functional connectivity. We applied the model to 10 bird species listed as endangered by the state of Illinois (U.S.A.). Spatial coherence and selection cost of the reserves differed substantially depending on the weights assigned to these 2 criteria. The model can be used to design a reserve system for multiple species, especially species whose habitats are far apart in which case multiple disjunct but compact and connected reserves are advantageous. The model can be modified to increase or decrease the distance between reserves to reduce or promote population connectivity.

  16. CO observations of high-z radio galaxies MRC 2104-242 and MRC 0943-242 : spectral-line performance of the Compact Array Broadband Backend

    NARCIS (Netherlands)

    Emonts, B. H. C.; Norris, R. P.; Feain, I.; Miley, G.; Sadler, E. M.; Villar-Martin, M.; Mao, M. Y.; Oosterloo, T. A.; Ekers, R. D.; Stevens, J. B.; Wieringa, M. H.; Coppin, K. E. K.; Tadhunter, C. N.

    2011-01-01

    We present the first 7-mm observations of two high-redshift, Ly alpha-bright radio galaxies (MRC 2104-242 and MRC 0943-242) performed with the 2 x 2 GHz instantaneous bandwidth of the Compact Array Broadband Backend (CABB) at the Australia Telescope Compact Array (ATCA). The aim was to search for (C

  17. Compact fusion reactors

    CERN Document Server

    CERN. Geneva

    2015-01-01

    Fusion research is currently to a large extent focused on tokamak (ITER) and inertial confinement (NIF) research. In addition to these large international or national efforts there are private companies performing fusion research using much smaller devices than ITER or NIF. The attempt to achieve fusion energy production through relatively small and compact devices compared to tokamaks decreases the costs and building time of the reactors and this has allowed some private companies to enter the field, like EMC2, General Fusion, Helion Energy, Lawrenceville Plasma Physics and Lockheed Martin. Some of these companies are trying to demonstrate net energy production within the next few years. If they are successful their next step is to attempt to commercialize their technology. In this presentation an overview of compact fusion reactor concepts is given.

  18. Compact torsatron reactors

    International Nuclear Information System (INIS)

    Low-aspect-ratio torsatron configurations could lead to compact stellarator reactors with R0 = 8--11m, roughly one-half to one-third the size of more conventional stellarator reactor designs. Minimum-size torsatron reactors are found using various assumptions. Their size is relatively insensitive to the choice of the conductor parameters and depends mostly on geometrical constraints. The smallest size is obtained by eliminating the tritium breeding blanket under the helical winding on the inboard side and by reducing the radial depth of the superconducting coil. Engineering design issues and reactor performance are examined for three examples to illustrate the feasibility of this approach for compact reactors and for a medium-size (R0 ≅ 4 m,/bar a/ /approx lt/ 1 m) copper-coil ignition experiment. 26 refs., 11 figs., 7 tabs

  19. Compactly Generated Domain Theory

    OpenAIRE

    Battenfeld, Ingo; Schröder, Matthias; Simpson, Alexander

    2006-01-01

    We propose compactly generated monotone convergence spaces as a well-behaved topological generalisation of directed-complete partial orders (dcpos). The category of such spaces enjoys the usual properties of categories of 'predomains' in denotational semantics. Moreover, such properties are retained if one restricts to spaces with a countable pseudobase in the sense of E. Michael, a fact that permits connections to be made with computability theory, realizability semantics and recent work on ...

  20. Energy report compact 2015

    International Nuclear Information System (INIS)

    The Energy Report compact 2015 from the Ministry of the Environment, Climate Protection and the Energy Sector and the State Office for Statistics Baden-Wuerttemberg provides an overview on the energy sector developments in Baden-Wuerttemberg in 2013. It contains numerous information on the energy consumption in Baden-Wuerttemberg, the energy productivity, the share of renewable energy sources, power generation and the energy-related CO2 emissions.

  1. Compact Quantum Groupoids

    OpenAIRE

    Landsman, N.P.

    1999-01-01

    Quantum groupoids are a joint generalization of groupoids and quantum groups. We propose a definition of a compact quantum groupoid that is based on the theory of C*-algebras and Hilbert bimodules. The essential point is that whenever one has a tensor product over the complex numbers in the theory of quantum groups, one now uses a certain tensor product over the base algebra of the quantum groupoid.

  2. Compact Torsatron configurations

    International Nuclear Information System (INIS)

    Low-aspect-ratio stellarator configurations can be realized by using torsatron winding. Plasmas with aspect ratios in the range of 3.5 to 5 can be confined by these Compact Torsatron configurations. Stable operation at high Β should be possible in these devices, if a vertical field coil system is adequately designed to avoid breaking of the magnetic surfaces at finite Β. 17 refs., 21 figs., 1 tab

  3. Utra-bright compact sources of correlated photons based on SPDC in periodically-poled KTP

    Science.gov (United States)

    Beausoleil, Ray; Fiorentino, Marco; Spillane, Sean; Roberts, Tony; Battle, Phil; Munroe, Mark

    2007-05-01

    Photon pairs generated using spontaneous parametric down- conversion (SPDC) have been a central ingredient for a number of quantum optics experiments ranging from the generation of entanglement to demonstrations of quantum information processing protocols. The flux of pairs generated by SPDC sources has been steadily growing over the years opening the door to practical applications of correlated and entangled photon pairs. SPDC sources based on periodically poled waveguides have shown a great potential to generate large numbers of correlated pairs with a few μW of pump. These works, however, lack a clear explanation of the increased pair rate in waveguides and do not directly compare the waveguide result with bulk. Na"ively, field confinement in waveguides is not expected to enhance pair generation rate, since SPDC is a scattering phenomenon that only involves one pump photon and therefore does not benefit from higher photon densities created by focussing. In this talk we present a theoretical and experimental comparison of spontaneous parametric down-conversion in periodically poled waveguides and bulk KTP crystals. We measured a waveguide pair generation rate of 2.9 .10^6 pairs/s per mW of pump in a 1-nm band: more than 50 times higher than the bulk crystal generation rate. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.E3.4

  4. Spectroscopic Surface Brightness Fluctuations: Amplifying Bright Stars in Unresolved Stellar Populations

    Science.gov (United States)

    Mitzkus, M.; Dreizler, S.; Roth, M. M.

    2015-08-01

    We report on our early-stage efforts to resolve the Surface Brightness Fluctuations (SBFs) in the spectral dimension. Combining the diagnostic power of SBFs with the physical information content of spectra seems a tempting possibility to gain new insights into the bright stars in unresolved stellar populations. The new VLT integral field spectrograph MUSE is the first instrument that enables spectroscopic SBFs observationally.

  5. Hydraulic conductivity of compacted zeolites.

    Science.gov (United States)

    Oren, A Hakan; Ozdamar, Tuğçe

    2013-06-01

    Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (γ(dmax)) of fine zeolite was greater than that of granular zeolites. The γ(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low γ(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study.

  6. LCD Projection Display System with High Brightness

    Institute of Scientific and Technical Information of China (English)

    Zhou Ping; Lu Wei; Zheng Zhenrong; Li Haifeng; Gu Peifu; Liu Xu

    2003-01-01

    A new compact XGA projection is designed with three 0.99" liquid crystal panels. By using 275W UHP lamp, above 3000 ANSI lumens could be achieved with the uniformity of 85%. The color temperature is 6742K.

  7. Observing Faint Companions Close to Bright Stars

    Science.gov (United States)

    Serabyn, Eugene

    2012-04-01

    Progress in a number of technical areas is enabling imaging and interferometric observations at both smaller angular separations from bright stars and at deeper relative contrast levels. Here we discuss recent progress in several ongoing projects at the Jet Propulsion Laboratory. First, extreme adaptive optics wavefront correction has recently enabled the use of very short (i.e., blue) wavelengths to resolve close binaries. Second, phase-based coronagraphy has recently allowed observations of faint companions to within nearly one diffraction beam width of bright stars. Finally, rotating interferometers that can observe inside the diffraction beam of single aperture telescopes are being developed to detect close-in companions and bright exozodiacal dust. This paper presents a very brief summary of the techniques involved, along with some illustrative results.

  8. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  9. The environment of Low Surface Brightness Galaxies

    OpenAIRE

    Rosenbaum, S. D.; Bomans, D. J.

    2004-01-01

    Using the Early Data Release of the Sloan Digital Sky Survey (SDSS) we investigated the clustering properties of Low Surface Brightness (LSB) galaxies in comparison to normal, High Surface Brightness (HSB) galaxies. We selected LSB galaxies and HSB galaxies with well measured redshifts from the SDSS data base and performed three-dimensional neighbour counting analysis within spheres of radii between 0.8 Mpc and 8.0 Mpc. As a second analysis method we used an N-th neighbour analysis with N var...

  10. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  11. COMPACT, TUNABLE COMPTON SCATTERING GAMMA-RAY SOURCES

    Energy Technology Data Exchange (ETDEWEB)

    Hartemann, F V; Albert, F; Anderson, G G; Anderson, S G; Bayramian, A J; Betts, S M; Chu, T S; Cross, R R; Ebbers, C A; Fisher, S E; Gibson, D J; Ladran, A S; Marsh, R A; Messerly, M J; O' Neill, K L; Semenov, V A; Shverdin, M Y; Siders, C W; McNabb, D P; Barty, C J; Vlieks, A E; Jongewaard, E N; Tantawi, S G; Raubenheimer, T O

    2009-08-20

    Recent progress in accelerator physics and laser technology have enabled the development of a new class of gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented.

  12. Compact Q-balls

    CERN Document Server

    Bazeia, D; Marques, M A; Menezes, R; da Rocha, R

    2016-01-01

    In this work we deal with non-topological solutions of the Q-ball type in two space-time dimensions, in models described by a single complex scalar field that engenders global symmetry. The main novelty is the presence of stable Q-balls solutions that live in a compact interval of the real line and appear from a family of models controlled by two distinct parameters. We find analytical solutions and study their charge and energy, and show how to control the parameters to make the Q-balls classically and quantum mechanically stable.

  13. Compact synchrotron light sources

    CERN Document Server

    Weihreter, Ernst

    1996-01-01

    This book covers a new niche in circular accelerator design, motivated by the promising industrial prospects of recent micromanufacturing methods - X-ray lithography, synchrotron radiation-based micromachining and microanalysis techniques. It describes the basic concepts and the essential challenges for the development of compact synchrotron radiation sources from an accelerator designer's point of view and gives an outline of the actual state of the art. The volume is intended as an introduction and as a reference for physicists, engineers and managers involved in this rapidly developing fiel

  14. Compact LINAC for deuterons

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S S [Los Alamos National Laboratory; O' Hara, J F [Los Alamos National Laboratory; Rybarcyk, L J [Los Alamos National Laboratory

    2008-01-01

    We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

  15. Brightness of synchrotron radiation from wigglers

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so-called 'depth-of-field' effects. In fact, the particle beam cross-section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. We exemplify this formalism in simple limiting cases. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in the literature.

  16. Dark Matter in Low Surface Brightness Galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; McGaugh, S. S.

    1996-01-01

    Abstract: Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that L

  17. Dark matter in low surface brightness galaxies

    NARCIS (Netherlands)

    de Blok, WJG; McGaugh, SS; Persic, M; Salucci, P

    1997-01-01

    Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that LSB galaxie

  18. Probable Bright Supernova discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-09-01

    A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  19. Brightness and darkness as perceptual dimensions.

    Directory of Open Access Journals (Sweden)

    Tony Vladusich

    2007-10-01

    Full Text Available A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D space varying from bright to dark. The results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  20. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  1. Alberta Associations for Bright Children Members' Handbook.

    Science.gov (United States)

    Alberta Association for Bright Children, Edmonton.

    This handbook is designed to provide information to parents of gifted children in Alberta, Canada. The handbook outlines the mission and objectives of the Alberta Associations for Bright Children and describes the structure of the non-profit organization. The booklet then addresses: (1) the characteristics of gifted children; (2) the rights of…

  2. A compact SADM family

    Science.gov (United States)

    Barbet, Vincent; Le Quintrec, Cyrille; Jeandot, Xavier; Chaix, Alain; Grain, Eric; Roux, Jerome

    2005-07-01

    Alcatel Space has developed a new SADM family driven by cost, modularity, mass and performances. The modularity concept is based on separating the rotation drive function from the electrical transfer function. The drive actuator has been designed for various applications where pointing and reliability is needed. It can be associated with high dissipative rotary devices (SA collectors, RF joints..). The design goal was to minimize the number of parts in order to reach the most simple and compact mechanism. Mass reduction was achieved by reducing as much as possible the load path between the Solar Array interface and the spacecraft interface. Following these guidelines, the drive actuator was developed and qualified on ATV SADM (part od Alcatel Space Solar Array Drive Sub System for ATV). Further more a high power integrated collector was qualified inside the SADM for Geo-stationary telecom satellite (SPACEBUS platforms). Fine thermal and mechanical modeling was necessary to predict SADM behaviors for the numerous thermal environments over the missions (steady and transient cases). These modeling were well correlated through mechanical and thermal balances qualification tests. The challenging approach of thermal dissipation in a compact design leads to a family of 3 SADM capabilities form 2kW up to 15kW per SADM weighing less than 4.5 kg each.

  3. 7 mm continuum observations of ultra compact HII regions

    OpenAIRE

    Leto, P.; Umana, G.; Trigilio, C.; Buemi, C. S.; Dolei, S.; Manzitto, P.; L. Cerrigone; Siringo, C.

    2009-01-01

    Ultra compact HII (UCHII) regions are indicators of high-mass star formation sites and are distributed mainly in the Galactic plane. We intend to investigate the possible contribution of the forthcoming ESA Planck mission to the science of UCHII regions by evaluating the possibility of detecting UCHIIs that are bright in the radio regime. We performed new 7 mm observations of a sample of UCHII regions. For each source in our sample, the free-free radio spectrum has been modeled. Along with fa...

  4. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

    OpenAIRE

    Youngstedt, Shawn D.; Kline, Christopher E.; Elliott, Jeffrey A; Zielinski, Mark; Devlin, Tina M.; Moore, Teresa A.

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness...

  5. High brightness beam shaping and fiber coupling of laser-diode bars.

    Science.gov (United States)

    Yu, Junhong; Guo, Linui; Wu, Hualing; Wang, Zhao; Tan, Hao; Gao, Songxin; Wu, Deyong; Zhang, Kai

    2015-04-10

    The strong beam quality mismatch in the fast and slow axes of laser-diode bars requires a significant beam shaping method to reach the parameters needed for fiber coupling. An effective solution to this problem is proposed that is based on a right-angle prism array and a distributed cylinder-lens stack. Coupling 12 mini-bars into a standard 100 μm core diameter and 0.15 numerical aperture fiber is achieved, and the output power can reach 400 W. Using this technique, production of compact and high brightness fiber-coupled laser-diode modules is possible.

  6. Soil compaction in forest soils

    OpenAIRE

    TURGUT, Bülent

    2012-01-01

    Soil compaction is a widespread degradation process in forest sites. Soil degradation occurring on the structural formation of a natural soil system by rainfall or mechanical outer forces generally results in soil particles to be rearranged tighter than its previous status. In this case, soil compaction -defined as the increase in bulk density of soil- develops with negative effects on soil-plant-water relations. With the compaction, the density of soil increases while the porosity rate decre...

  7. Compaction properties of agricultural soils

    OpenAIRE

    TANG, Anh Minh; CUI, Yu Jun; Eslami, Javad; DEFOSSEZ BERTHOUD, Pauline

    2007-01-01

    The compaction of field soils due to repeated rolling of agricultural vehicles is one of the main reasons for the agricultural soil degradation. A good understanding of the compaction properties of these soils is essential for an optimum organisation of agricultural activities, and therefore for environmental protection in terms of nitrate migrations. In the present work, the compaction properties of agricultural soils from four sites in France are studied after experimental data ...

  8. Compact SPS - Power delivery

    Science.gov (United States)

    Pospisil, M.; Pospisilova, L.

    1982-09-01

    The power deliverable by a compact solar Space Power Station (SPS) is a function of its outer surface shape. Methods of fitting the power delivery curve of such a system to different patterns of daily power demand are considered that involve the appropriate choice of the number of satellites, their maximal power, height to width ratio and the shift of longitude with respect to the receiving station. Changes in the daily delivery curve can be made by altering the longitudes and orientations of the satellites. Certain limitations to the choice of parameters exist, such as: the height to width ratio should be near 1.2, and the sum of longitude and orientation changes will probably not be greater than 50 deg. The optimization of the peak to average power ratio is also discussed.

  9. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel

    2014-01-01

    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  10. Compact cryocooler heat exchangers

    International Nuclear Information System (INIS)

    Compact heat exchangers are subject to different constraints as a room temperature gas is cooled down by a cold stream returning from a JT valve (or a similar cryoprocess component). In particular, the optimization of exchangers for liquid helium systems has to cover a wide range in temperature and density of the fluid. In the present work we address the following thermodynamic questions: 1. The optimization of intermediate temperatures which optimize stage operation (a stage is assumed to have a constant cross section); 2. The optimum temperature difference available for best overall economic performance values. The results are viewed in the context of porous media concepts applied to rather low speeds of fluid flow in narrow passages. In this paper examples of fluid/solid constraints imposed in this non-classical low temperature area are presented

  11. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  12. Quantum Bright Soliton in a Disorder Potential

    Science.gov (United States)

    Sacha, K.; Delande, D.; Zakrzewski, J.

    2009-11-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particular, in the presence of a disordered potential, the quantum motion of the center of mass of a bright soliton may exhibit Anderson localization, on a localization length which may be much larger than the soliton size and could be observed experimentally.

  13. The Meaning of a Compact

    Science.gov (United States)

    Wasescha, Anna

    2016-01-01

    To mark the 30th anniversary of "Campus Compact," leaders from across the network came together in the summer of 2015 to reaffirm a shared commitment to the public purposes of higher education. Campus Compact's 30th Anniversary Action Statement of Presidents and Chancellors is the product of that collective endeavor. In signing the…

  14. The Finslerian compact star model

    Energy Technology Data Exchange (ETDEWEB)

    Rahaman, Farook; Paul, Nupur [Jadavpur University, Department of Mathematics, Kolkata, West Bengal (India); De, S.S. [University of Calcutta, Department of Applied Mathematics, Kolkata (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Jafry, M.A.K. [Shibpur Dinobundhoo Institution, Department of Physics, Howrah, West Bengal (India)

    2015-11-15

    We construct a toy model for compact stars based on the Finslerian structure of spacetime. By assuming a particular mass function, we find an exact solution of the Finsler-Einstein field equations with an anisotropic matter distribution. The solutions are revealed to be physically interesting and pertinent for the explanation of compact stars. (orig.)

  15. Warm compacting behavior of stainless steel powders

    Institute of Scientific and Technical Information of China (English)

    肖志瑜; 柯美元; 陈维平; 召明; 李元元

    2004-01-01

    The warm compacting behaviors of four different kinds of stainless steel powders, 304L, 316L, 410L and 430L, were studied. The results show that warm compaction can be applied to stainless steel powders. The green densities and strengths of compacts obtained through warm compaction are generally higher than those obtained through cold compaction. The compacting behaviors in warm compaction and cold compaction are similar.Under the compacting pressure of 700 MPa, the warm compacted densities are 0. 10 - 0.22 g/cm3 higher than the cold compacted ones, and the green strengths are 11.5 %-50 % higher. The optimal warm compacting temperature is 100 - 110 ℃. In the die wall lubricated warm compaction, the optimum internal lubricant content is 0.2%.

  16. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  17. Surface Brightness Fluctuations as Stellar Population Indicators

    OpenAIRE

    Blakeslee, John P

    2009-01-01

    Surface Brightness Fluctuations (SBF) can provide useful information about the unresolved stellar content of early-type galaxies and spiral bulges. The absolute SBF magnitude Mbar in a given passband depends on the properties of the stellar population and can be predicted by population synthesis models. SBF measurements in different bandpasses are sensitive to different evolutionary stages within the galaxy stellar population. Near-IR SBF magnitudes are sensitive to the evolution of stars wit...

  18. Bright Solitary Waves in Malignant Gliomas

    OpenAIRE

    Pérez-García, Víctor M.; Calvo, Gabriel F.; Belmonte-Beitia, Juan; Diego, D.; Pérez-Romasanta, Luis

    2011-01-01

    We put forward a nonlinear wave model describing the fundamental physio-pathologic features of an aggressive type of brain tumors: glioblastomas. Our model accounts for the invasion of normal tissue by a proliferating and propagating rim of active glioma cancer cells in the tumor boundary and the subsequent formation of a necrotic core. By resorting to numerical simulations, phase space analysis and exact solutions, we prove that bright solitary tumor waves develop in such systems.

  19. Extreme Ultraviolet Explorer Bright Source List

    Science.gov (United States)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  20. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  1. The Bright SHARC Survey The Cluster Catalog

    CERN Document Server

    Romer, A K; Holden, B P; Ulmer, M P; Pildis, R A; Merrelli, A J; Adami, C; Burke, D J; Collins, C A; Metevier, A J; Kron, Richard G; Commons, K

    1999-01-01

    We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 sq.deg and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified thirty-seven clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696Bright SHARC clusters have not been listed in any previously ...

  2. Search for bright stars with infrared excess

    International Nuclear Information System (INIS)

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25μm (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m12−m25>0; where m12−m25 = −2.5log(F12/F25)+1.56, where F12 and F25 are flux density in Jansky at 12 and 25μm, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars

  3. LA Palma Night-Sky Brightness

    CERN Document Server

    Benn, C R; Benn, Chris R.; Ellison, Sara L.

    1998-01-01

    The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky brightness at high elevation, high galactic latitude and high ecliptic latitude, at sunspot minimum, is B = 22.7, V = 21.9, R = 21.0, similar to that at other dark sites. The main contributions to sky brightness are airglow and zodiacal light. The sky is brighter at low ecliptic latitude (by 0.4 mag); at solar maximum (by 0.4 mag); and at high airmass (0.25 mag brighter at airmass 1.5). Light pollution (line + continuum) contributes < 0.03 mag in U, approximately 0.02 mag in B, approximately 0.10 mag in V, approximately and 0.10 mag in R at the zenith. This paper is a summary of results which are presented in full elsewhere (Benn & Ellison 1998, La Palma Technical Note 115).

  4. Boundaries of flat compact surfaces

    DEFF Research Database (Denmark)

    Røgen, Peter

    1999-01-01

    This paper deals with the problem: ``Which knots or links in 3-space bound flat (immersed) compact surfaces?''. In a previous paper by the author it was proven that: Any simple closed space curve can be deformed until it bounds a flat orientable compact (Seifert) surface. The main results...... of this paper are: There exist knots that do not bound any flat compact surfaces. The lower bound of total curvature of a knot bounding an orientable non-negatively curved compact surface can, for varying knot type, be arbitrarily much greater than the infimum of curvature needed for the knot to have its knot...... type. The number of $3$-singular points (points of zero curvature or if not then of zero torsion) on the boundary of a flat immersed compact surface is greater than or equal to twice the absolute value of the Euler characteristic of the surface. A set of necessary and, in a weakened sense, sufficient...

  5. A Compact Ring Design with Tunable Momentum Compaction

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.; /SLAC

    2012-05-17

    A storage ring with tunable momentum compaction has the advantage in achieving different RMS bunch length with similar RF capacity, which is potentially useful for many applications, such as linear collider damping ring and predamping ring where injected beam has a large energy spread and a large transverse emittance. A tunable bunch length also makes the commissioning and fine tuning easier in manipulating the single bunch instabilities. In this paper, a compact ring design based on a supercell is presented, which achieves a tunable momentum compaction while maintaining a large dynamic aperture.

  6. What will blue compact dwarf galaxies evolve into?

    CERN Document Server

    Meyer, Hagen T; Janz, Joachim; Papaderos, Polychronis

    2013-01-01

    We present and analyse the photometric properties of a nearly complete sample of blue compact dwarf (BCD) and irregular galaxies in the Virgo cluster from multi-band SDSS images. Our study intends to shed light on the ongoing debate of whether a structural evolution from present-day star-forming dwarf galaxies in a cluster environment into ordinary early-type dwarf galaxies is possible based on the structural properties. For this purpose, we decompose the surface brightness profiles of the BCDs into the luminosity contribution of the starburst component and that of their underlying low surface brightness (LSB) host. The latter dominates the stellar mass of the BCD. We find that the LSB-components of the Virgo BCDs are structurally compatible with the more compact half of the Virgo early-type dwarfs, except for a few extreme BCDs. Thus, after termination of starburst activity, the BCDs will presumably fade into galaxies that are structurally similar to ordinary early-type dwarfs. In contrast, the irregulars ar...

  7. Ultra-Compact Dwarfs around NGC 3258 in Antlia

    CERN Document Server

    Caso, Juan Pablo; Richtler, T; Castelli, A V Smith; Faifer, Favio; 10.1093/mnras/sts687

    2013-01-01

    We present the first compact stellar systems with luminosities in the range of ultra-compact dwarfs (UCDs), discovered in the Antlia galaxy cluster (-10.5 < M_V < -11.6). The magnitude limit between UCDs and globular clusters (CGs) is discussed. By means of imaging from VLT (FORS1), CTIO (MOSAIC), and the HST (ACS) archive, eleven UCDs/bright GCs are selected on the basis of photometry and confirmed as Antlia members through radial velocities measured on new GEMINI (GMOS-S) spectra. In addition, nine UCD candidates are identified taking into account properties derived from their surface brightness profiles. All of them, members and candidates, are located in the proximity of NGC\\,3258, one of the two brightest elliptical galaxies in the cluster core. Antlia UCDs in this sample present absolute magnitudes fainter than M_V ~ -11.6 mag and most of them have colours within the blue GC range, falling only two within the red GC range. Effective radii measured for the ones lying on the ACS field are in the ran...

  8. Faint Dwarf Galaxies in Hickson Compact Group 90

    CERN Document Server

    Ordenes-Briceño, Yasna; Puzia, Thomas H; Muñoz, Roberto P; Eigenthaler, Paul; Georgiev, Iskren Y; Goudfrooij, Paul; Hilker, Michael; Lançon, Ariane; Mamon, Gary; Mieske, Steffen; Miller, Bryan W; Peng, Eric W; Sánchez-Janssen, Rubén

    2016-01-01

    We report the discovery of a very diverse set of five low-surface brightness (LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in deep U- and I-band images obtained with VLT/VIMOS. These are the first LSB dwarf galaxy candidates found in a compact group of galaxies. We measure spheroid half-light radii in the range $0.7\\!\\lesssim\\! r_{\\rm eff}/{\\rm kpc}\\! \\lesssim\\! 1.5$ with luminosities of $-11.65\\!\\lesssim\\! M_U\\! \\lesssim\\! -9.42$ and $-12.79\\!\\lesssim\\! M_I\\! \\lesssim\\! -10.58$ mag, corresponding to a color range of $(U\\!-\\!I)_0\\!\\simeq\\!1.1\\!-\\!2.2$ mag and surface brightness levels of $\\mu_U\\!\\simeq\\!28.1\\,{\\rm mag/arcsec^2}$ and $\\mu_I\\!\\simeq\\!27.4\\,{\\rm mag/arcsec^2}$. Their colours and luminosities are consistent with a diverse set of stellar population properties. Assuming solar and 0.02 Z$_\\odot$ metallicities we obtain stellar masses in the range $M_*|_{Z_\\odot} \\simeq 10^{5.7-6.3} M_{\\odot}$ and $M_*|_{0.02\\,Z_\\odot}\\!\\simeq\\!10^{6.3-8}\\,M_{\\odot}$. Three dwarfs are ol...

  9. A Compact Supermassive Binary Black Hole System

    CERN Document Server

    Rodríguez, C; Zavala, R T; Peck, A B; Pollack, L K; Romani, R W

    2006-01-01

    We report on the discovery of a supermassive binary black hole system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the closest black hole pair yet found by more than two orders of magnitude. These results are based upon recent multi-frequency observations using the Very Long Baseline Array (VLBA) which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multi-epoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. Low spectral resolution spectroscopy using the Hobby-Eberly Telescope indicates two velocity systems with a combined mass of the two black holes of ~1.5 x 10^8 solar masses. The two nuclei appear stationary while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of close binary black holes that might be sources of gravi...

  10. The Planck Compact Source Catalogues: present and future.

    Science.gov (United States)

    López-Caniego, Marcos

    2015-08-01

    The Planck Collaboration has produced catalogues of radio and sub-mm compact sources at the nine Planck frequencies, Galactic cold clumps catalogues and SZ cluster catalogues. But new catalogues are foreseen. A multifrequency compact source catalogue will be produced selecting sources at radio frequencies and following them across all Planck bands. Multifrequency catalogues can be difficult to produce in experiments like Planck with a large frequency coverage and very different resolutions across bands, but the science that can be extracted from such a catalogue compensates the effort. In addition, for those sources where a clear identification can be made, we will attempt to include flux density information from Herschel and other experiments, in particular for those blazars that are bright in radio, sub-mm and even in gamma-ray frequencies, as seen by Fermi. Moreover, Planck is making available to the community the single survey frequency maps that will allow astronomers to study the long-term variability of their favourite sources. New functionalities will be added to the Planck Legacy Archive, for example a timeline-cutting tool that will allow one to extract maps from the Planck timelines for specific periods of time allowing short-term variability studies of compact sources (e.g., flares). The unique frequency coverage of Planck make these catalogues very valuable for other experiments using the Planck compact source catalogues. For example, experiments like QUIJOTE use Planck selected sources to study the impact of polarized radio source emission on their cosmological fields and other CMB experiments will use Planck polarized compact source information for calibration.

  11. Compact Grism Spectrometer

    Science.gov (United States)

    Teare, S. W.

    2003-05-01

    Many observatories and instrument builders are retrofitting visible and near-infrared spectrometers into their existing imaging cameras. Camera designs that reimage the focal plane and have the optical filters located in a pseudo collimated beam are ideal candidates for the addition of a spectrometer. One device commonly used as the dispersing element for such spectrometers is a grism. The traditional grism is constructed from a prism that has had a diffraction grating applied on one surface. The objective of such a design is to use the prism wedge angle to select the desired "in-line" or "zero-deviation" wavelength that passes through on axis. The grating on the surface of the prism provides much of the dispersion for the spectrometer. A grism can also be used in a "constant-dispersion" design which provides an almost linear spatial scale across the spectrum. In this paper we provide an overview of the development of a grism spectrometer for use in a near infrared camera and demonstrate that a compact grism spectrometer can be developed on a very modest budget that can be afforded at almost any facility. The grism design was prototyped using visible light and then a final device was constructed which provides partial coverage in the near infrared I, J, H and K astronomical bands using the appropriate band pass filter for order sorting. The near infrared grism presented here provides a spectral resolution of about 650 and velocity resolution of about 450 km/s. The design of this grism relied on a computer code called Xspect, developed by the author, to determine the various critical parameters of the grism. This work was supported by a small equipment grant from NASA and administered by the AAS.

  12. Compact instantaneous water heater

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, Jorge G.W.; Machado, Antonio R.; Ferraz, Andre D.; Rocha, Ivan C.C. da; Konishi, Ricardo [Companhia de Gas de Santa Catarina (SCGAS), Florianopolis, SC (Brazil); Lehmkuhl, Willian A.; Francisco Jr, Roberto W.; Hatanaka, Ricardo L.; Pereira, Fernando M.; Oliveira, Amir A.M. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2012-07-01

    This paper presents an experimental study of combustion in an inert porous medium in a liquid heating device application. This project aims to increase efficiency in the application of natural gas in residential and commercial sectors with the use of advanced combustion and heat transfer. The goal is to facilitate the development of a high performance compact water heater allowing hot water supply for up to two simultaneous showers. The experiment consists in a cylindrical porous burner with an integrated annular water heat exchanger. The reactants were injected radially into the burner and the flame stabilizes within the porous matrix. The water circulates in a coiled pipe positioned at the center of the burner. This configuration allows for heat transfer by conduction and radiation from the solid matrix to the heat exchanger. This article presented preliminary experimental results of a new water heater based on an annular porous burner. The range of equivalence ratios tested varied from 0.65 to 0.8. The power range was varied from 3 to 5 kW. Increasing the equivalence ratio or decreasing the total power input of the burner resulted in increased thermal efficiencies of the water heater. Thermal efficiencies varying from 60 to 92% were obtained. The condition for the goal of a comfortable bath was 20 deg C for 8-12 L/min. This preliminary prototype has achieved water temperature of 11deg C for 5 L/min. Further optimizations will be necessary in order to achieve intense heating with high thermal efficiency. (author)

  13. Development of a compact FEL system and its technological applications for x-ray generation

    International Nuclear Information System (INIS)

    Using a 6MeV S-band rf linac, a compact FEL system for a wide wavelength range is being developed at ILT/ILE Osaka University. It covers radiation wavelengths from ∼10 μm to a few millimeters. A photocathode driven by a Nd:YAG laser was installed in the rf gun to improve the beam quality. The photocathode operation was investigated in detail by our simulation code. As an application of the FEL technology, study of a compact high-brightness x-ray source is in progress. Compton scattering between relativistic e-beam and laser beam generates spectrally bright x-rays. Higher harmonics generation of the scattered x-rays by nonlinear Thomson scattering is also investigated numerically. (author)

  14. Evolution of bulgeless low surface brightness galaxies

    Science.gov (United States)

    Shao, X.; Hammer, F.; Yang, Y. B.; Liang, Y. C.

    Based on the Sloan Digital Sky Survey DR 7, we investigate the environment, morphology, and stellar population of bulgeless low surface-brightness (LSB) galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04 and M r LSB galaxies have more young stars and are more metal-poor than regular LSB galaxies. These results suggest that the evolution of LSB galaxies may be driven by their dynamics, including mergers rather than by their large-scale environment.

  15. Raman beam combining for laser brightness enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  16. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  17. Monitoring of bright blazars with MAGIC telescope

    OpenAIRE

    Hsu, C. C.; Satalecka, K.; Thom, M; Backes, M.; Bernardini, E.; Bonnoli, G.; Galante, N.; Goebel, F; Lindfors, E.; Majumdar, P.; Stamerra, A.; Wagner, R. M.

    2009-01-01

    Blazars, a class of Active Galactic Nuclei (AGN) characterized by a close orientation of their relativistic outflows (jets) towards the line of sight, are a well established extragalactic TeV $\\gamma$-ray emitters. Since 2006, three nearby and TeV bright blazars, Markarian (Mrk) 421, Mrk 501 and 1ES 1959+650, are regularly observed by the MAGIC telescope with single exposures of 30 to 60 minutes. The sensitivity of MAGIC allows to establish a flux level of 30% of the Crab flux for each such o...

  18. Quantum bright soliton in a disorder potential

    OpenAIRE

    Sacha, K.; Delande, D; Zakrzewski, J.

    2009-01-01

    At very low temperature, a quasi-one-dimensional ensemble of atoms with attractive interactions tend to form a bright soliton. When exposed to a sufficiently weak external potential, the shape of the soliton is not modified, but its external motion is affected. We develop in detail the Bogoliubov approach for the problem, treating, in a non-perturbative way, the motion of the center of mass of the soliton. Quantization of this motion allows us to discuss its long time properties. In particula...

  19. The role of the Fraunhofer lines in solar brightness variability

    CERN Document Server

    Shapiro, A I; Krivova, N A; Tagirov, R V; Schmutz, W K

    2015-01-01

    The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and waveleng...

  20. What Is Business's Social Compact?

    Science.gov (United States)

    Avishai, Bernard

    1994-01-01

    Under the "new" social compact, businesses must focus on continuous learning and thus have both an obligation to support teaching and an opportunity to profit from it. Learning organizations must also be teaching organizations. (SK)

  1. Compact energy conversion module Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This STTR project delivers a compact vibration-based Energy Conversion Module (ECM) that powers sensors for purposes like structural health monitoring (SHM). NASA...

  2. Compact, Ultrasensitive Formaldehyde Monitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Small Business Innovative Research Phase II proposal seeks to develop a compact UV laser ?based sensor for Earth science and planetary atmosphere exploration....

  3. Countably determined compact abelian groups

    CERN Document Server

    Dikranjan, Dikran

    2008-01-01

    For an abelian topological group G let G^* be the dual group of all continuous characters endowed with the compact open topology. A subgroup D of G determines G if the restriction homomorphism G^* --> D^* of the dual groups is a topological isomorphism. Given a scattered compact subset X of an infinite compact abelian group G such that |X|compact abelian group determined by its countable subgroup must be metrizable. This gives a negative answer to questions of Comfort, Hernandez, Macario, Raczkowski and Trigos-Arrieta, as well as provides short proofs of main results established in three manuscripts by these authors.

  4. Compact, Airborne Multispecies Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Small Business Innovative Research Phase I proposal seeks to develop a compact mid-infrared laser spectrometer to benefit Earth science research activities. To...

  5. Compact Massive Object in Galaxies

    CERN Document Server

    Melo, I Tosta e

    2016-01-01

    The central regions of galaxies show the presence of super massive black holes and/or very dense stellar clusters. Both objects seem to follow similar host-galaxy correlations, suggesting that they are members of the same family of Compact Massive Objects. We investigate here a huge data collection of Compact Massive Objects properties to correlate them with absolute magnitude, velocity dispersion and mass of their host galaxies.

  6. Coronal bright points associated with minifilament eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Yang, Bo; Yang, Dan, E-mail: hjcsolar@ynao.ac.cn [Also at Graduate School of Chinese Academy of Sciences, Beijing, China. (China)

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  7. Sublimation in bright spots on (1) Ceres.

    Science.gov (United States)

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense. PMID:26659183

  8. At Bright Band Inside Victoria Crater

    Science.gov (United States)

    2007-01-01

    A layer of light-toned rock exposed inside Victoria Crater in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the crater. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the crater. Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of 2.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band. Victoria Crater has a scalloped shape of alternating alcoves and promontories around the crater's circumference. Opportunity descended into the crater two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'

  9. Globe at Night - Sky Brightness Monitoring Network

    Science.gov (United States)

    Cheung, Sze Leung; Pun, Jason Chun Shing; SO, Chu-wing; Shibata, Yukiko; Walker, Constance Elaine; Agata, Hidehiko

    2015-08-01

    The Global at Night - Sky Brightness Monitoring Network (GaN-MN) is an international project for long-term monitoring of night sky conditions around the world. The GaN-MN consists of fixed monitoring stations each equipped with a Sky Quality Meter - Lensed Ethernet (SQM-LE), which is a specialized light sensor for night sky brightness (NSB) measurement. NSB data are continuously collected at high sampling frequency throughout the night, and these data will be instantly made available to the general public to provide a real-time snapshot of the global light pollution condition. A single data collection methodology, including data sampling frequency, data selection criteria, device design and calibration, and schemes for data quality control, was adopted to ensure uniformity in the data collected. This is essential for a systematic and global study of the level of light pollution. The data collected will also provide the scientific backbone in our efforts to contribute to dark sky conservation through education to the general public and policy makers. The GaN-MN project is endorsed by the IAU IYL Executive Committee Working Group as a major Cosmic Light program in the International Year of Light.

  10. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  11. Coronal bright points associated with minifilament eruptions

    International Nuclear Information System (INIS)

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 109 cm–3. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  12. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  13. Compact boson stars in K field theories

    Science.gov (United States)

    Adam, C.; Grandi, N.; Klimas, P.; Sánchez-Guillén, J.; Wereszczyński, A.

    2010-11-01

    We study a scalar field theory with a non-standard kinetic term minimally coupled to gravity. We establish the existence of compact boson stars, that is, static solutions with compact support of the full system with self-gravitation taken into account. Concretely, there exist two types of solutions, namely compact balls on the one hand, and compact shells on the other hand. The compact balls have a naked singularity at the center. The inner boundary of the compact shells is singular, as well, but it is, at the same time, a Killing horizon. These singular, compact shells therefore resemble black holes.

  14. Compact boson stars in K field theories

    CERN Document Server

    Adam, C; Klimas, P; Sánchez-Guillén, J; Wereszczynski, A

    2009-01-01

    We study a scalar field theory with a non-standard kinetic term minimally coupled to gravity. We establish the existence of compact boson stars, that is, static solutions with compact support of the full system with self-gravitation taken into account. Concretely, there exist two types of solutions, namely compact balls on the one hand, and compact shells on the other hand. The compact balls have a naked singularity at the center. The inner boundary of the compact shells is singular, as well, but it is, at the same time, a Killing horizon. These singular, compact shells therefore resemble black holes.

  15. Modelling Solar and Stellar Brightness Variabilities

    Science.gov (United States)

    Yeo, K. L.; Shapiro, A. I.; Krivova, N. A.; Solanki, S. K.

    2016-04-01

    Total and spectral solar irradiance, TSI and SSI, have been measured from space since 1978. This is accompanied by the development of models aimed at replicating the observed variability by relating it to solar surface magnetism. Despite significant progress, there remains persisting controversy over the secular change and the wavelength-dependence of the variation with impact on our understanding of the Sun's influence on the Earth's climate. We highlight the recent progress in TSI and SSI modelling with SATIRE. Brightness variations have also been observed for Sun-like stars. Their analysis can profit from knowledge of the solar case and provide additional constraints for solar modelling. We discuss the recent effort to extend SATIRE to Sun-like stars.

  16. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  17. High brightness angled cavity quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, D.; Bai, Y.; Bandyopadhyay, N.; Slivken, S.; Razeghi, M., E-mail: razeghi@eecs.northwestern.edu [Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-03-02

    A quantum cascade laser (QCL) with an output power of 203 W is demonstrated in pulsed mode at 283 K with an angled cavity. The device has a ridge width of 300 μm, a cavity length of 5.8 mm, and a tilt angle of 12°. The back facet is high reflection coated, and the front facet is anti-reflection coated. The emitting wavelength is around 4.8 μm. In distinct contrast to a straight cavity broad area QCL, the lateral far field is single lobed with a divergence angle of only 3°. An ultrahigh brightness value of 156 MW cm{sup −2 }sr{sup −1} is obtained, which marks the brightest QCL to date.

  18. Brightness temperature for 166 radio sources

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong Huang; Yu-Hai Yuan; Jiang-He Yang; Yi Liu; Jun Tao; Ying Gao; Tong-Xu Hua; Rui-Guang Lin; Jiang-Shui Zhang; Jing-Yi Zhang; Yi-Ping Qin

    2009-01-01

    Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8, 8 and 14.5 GHz), we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528-250) with an average timescale of △tobs=17.1±16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06 K. In addition, we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.

  19. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  20. Considerations for high-brightness electron sources

    International Nuclear Information System (INIS)

    Particle accelerators are now used in many areas of physics research and in industrial and medical applications. New uses are being studied to address major societal needs in energy production, materials research, generation of intense beams of radiation at optical and suboptical wavelengths, treatment of various kinds of waste, and so on. Many of these modern applications require a high intensity beam at the desired energy, along with a very good beam quality in terms of the beam confinement, aiming, or focusing. Considerations for ion and electron accelerators are often different, but there are also many commonalties, and in fact, techniques derived for one should perhaps more often be considered for the other as well. We discuss some aspects of high-brightness electron sources here from that point of view. 6 refs

  1. Dark Skies, Bright Kids Year 7

    Science.gov (United States)

    Bittle, Lauren E.; Johnson, Kelsey E.; Borish, H. Jacob; Burkhardt, Andrew; Firebaugh, Ariel; Hancock, Danielle; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; Prager, Brian; Pryal, Matthew; Sokal, Kimberly R.; Troup, Nicholas William; Wenger, Trey

    2016-01-01

    We present updates from our seventh year of operation including new club content, continued assessments, and our fifth annual Star Party. Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.

  2. Co-compact Gabor Systems on Locally Compact Abelian Groups

    DEFF Research Database (Denmark)

    Jakobsen, Mads Sielemann; Lemvig, Jakob

    2016-01-01

    characterization results via the Zak transform. From these results we derive non-existence results for critically sampled continuous Gabor frames. We obtain general characterizations in time and in frequency domain of when two Gabor generators yield dual frames. Moreover, we prove the Walnut and Janssen......-compact subgroups. Our results only rely on the assumption that either one of the translation and modulation group (in some cases both) are co-compact subgroups of the time and frequency domain. This presentation offers a unified approach to the study of continuous and the discrete Gabor frames....

  3. Viral RNAs are unusually compact.

    Directory of Open Access Journals (Sweden)

    Ajaykumar Gopal

    Full Text Available A majority of viruses are composed of long single-stranded genomic RNA molecules encapsulated by protein shells with diameters of just a few tens of nanometers. We examine the extent to which these viral RNAs have evolved to be physically compact molecules to facilitate encapsulation. Measurements of equal-length viral, non-viral, coding and non-coding RNAs show viral RNAs to have among the smallest sizes in solution, i.e., the highest gel-electrophoretic mobilities and the smallest hydrodynamic radii. Using graph-theoretical analyses we demonstrate that their sizes correlate with the compactness of branching patterns in predicted secondary structure ensembles. The density of branching is determined by the number and relative positions of 3-helix junctions, and is highly sensitive to the presence of rare higher-order junctions with 4 or more helices. Compact branching arises from a preponderance of base pairing between nucleotides close to each other in the primary sequence. The density of branching represents a degree of freedom optimized by viral RNA genomes in response to the evolutionary pressure to be packaged reliably. Several families of viruses are analyzed to delineate the effects of capsid geometry, size and charge stabilization on the selective pressure for RNA compactness. Compact branching has important implications for RNA folding and viral assembly.

  4. Moon night sky brightness simulation for the Xinglong station

    International Nuclear Information System (INIS)

    Using a sky brightness monitor at the Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences, we collected data from 22 dark clear nights and 90 moon nights. We first measured the sky brightness variation with time for dark nights and found a clear correlation between sky brightness and human activity. Then with a modified sky brightness model of moon nights and data from these nights, we derived the typical value for several important parameters in the model. With these results, we calculated the sky brightness distribution under a given moon condition for the Xinglong station. Furthermore, we simulated the sky brightness distribution of a moon night for a telescope with a 5° field of view (such as LAMOST). These simulations will be helpful for determining the limiting magnitude and exposure time, as well as planning the survey for LAMOST during moon nights

  5. High brightness laser source based on polarization coupling of two diode lasers with asymmetric feedback

    DEFF Research Database (Denmark)

    Thestrup, B.; Chi, M.; Sass, B.;

    2003-01-01

    In this letter, we show that polarization coupling and asymmetric diode-laser feedback can be used to combine two diode-laser beams with low spatial coherence into a single beam with high spatial coherence. The coupled laser source is based on two similar laser systems each consisting of a 1 mumx......200 mum broad area laser diode applied with a specially designed feedback circuit. When operating at two times threshold, 50% of the freely running system output power is obtained in a single beam with an M-2 beam quality factor of 1.6+/-0.1, whereas the M-2 values of the two freely running diode...... lasers are 29+/-1 and 34+/-1, respectively. (C) 2003 American Institute of Physics....

  6. Annular bright and dark field imaging of soft materials

    International Nuclear Information System (INIS)

    Here polyethylene, as an example of an important soft material, was studied by STEM annular bright and dark field. The contrast as function of the probe size/shape and the detector collection angle are discussed. The results are compared to conventional bright field transmission electron microscopy, electron energy filtered imaging and energy dispersive spectroscopy mapping. Annular bright and dark field gave a higher contrast than conventional transmission and analytical mapping techniques

  7. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  8. Probing the Environment of Accreting Compact Objects

    Science.gov (United States)

    Hanke, Manfred

    2011-04-01

    X-ray binaries are the topic of this thesis. They consist of a compact object -- a black hole or a neutron star -- and an ordinary star, which loses matter to the compact object. The gravitational energy released through this process of mass accretion is largely converted into X-rays. The latter are used in the present work to screen the environment of the compact object. The main focus in the case of a massive star is on its wind, which is not homogeneous, but may display structures in form of temperature and density variations. Since great importance is, in multiple respects, attached to stellar winds in astrophysics, there is large interest in general to understand these structures more thoroughly. In particular for X-ray binaries, whose compact object obtains matter from the wind of its companion star, the state of the wind can decisively influence mass accretion and its related radiation processes. A detailed introduction to the fundamentals of stellar winds, compact objects, accretion and radiation processes in X-ray binaries, as well as to the employed instruments and analysis methods, is given in chapter 1. The focus of this investigation is on Cygnus X-1, a binary system with a black hole and a blue supergiant, which form a persistently very bright X-ray source because of accretion from the stellar wind. It had been known for a long time that this source -- when the black hole is seen through the dense stellar wind -- often displays abrupt absorption events whose origin is suspected to be in clumps in the wind. More detailed physical properties of these clumps and of the wind in general are explored in this work. Observations that were specifically acquired for this study, as well as archival data from different satellite observatories, are analyzed in view of signatures of the wind and its fine structures. These results are presented in chapter 2. In a first part of the analysis, the statistical distribution of the brightness of Cyg X-1, as measured since

  9. The United Nations Global Compact

    DEFF Research Database (Denmark)

    Rasche, Andreas; Waddock, Sandra; McIntosh, Malcolm

    2013-01-01

    This article reviews the interdisciplinary literature on the UN Global Compact. The review identifies three research perspectives, which scholars have used to study the UN Global Compact so far: a historical perspective discussing the Global Compact in the context of UN-business relations......, an operational perspective discussing the composition and impact of its participants, as well as a governance perspective discussing the constraints and opportunities of the initiative as an institutionalized arena for addressing global governance gaps. The authors contrast these three perspectives and identify...... key empirical as well as conceptual scholarly contributions. The remainder of this article contains focused summaries of the articles selected for this Special Issue. All articles are introduced and evaluated against the background of the three research perspectives....

  10. A bright attosecond x-ray pulse train generation in a double-laser-driven cone target

    Science.gov (United States)

    Hu, Li-Xiang; Yu, Tong-Pu; Shao, Fu-Qiu; Luo, Wen; Yin, Yan

    2016-06-01

    By using full three-dimensional particle-in-cell and Monte Carlo simulations, we investigate the generation of a high-brightness attosecond x-ray pulse train in a double-laser-driven cone target. The scheme makes use of two lasers: the first high-intensity laser with a laser peak intensity 1.37 × 1020 W/cm2 irradiates the cone and produces overdense attosecond electron bunches; the second counterpropagating weakly relativistic laser with a laser peak intensity 4.932 × 1017 W/cm2 interacts with the produced electron bunches and a bright x-ray pulse train is generated by Thomson backscattering of the second laser off the attosecond electron bunches. It is shown that the photon flux rises by 5 times using the cone target as compared with a normal channel. Meanwhile, the x-ray peak brightness increases significantly from 1.4 × 1021/(s mm2 mrad2 0.1 keV) to 6.0 × 1021/(s mm2 mrad2 0.1 keV), which is much higher than that of the Thomson x-ray source generated from traditional accelerators. We also discuss the influence of the laser and target parameters on the x-ray pulse properties. This compact bright x-ray source may have diverse applications, e.g., the study of electric dynamics and harmonics emission in the atomic scale.

  11. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    OpenAIRE

    Kátia M. M. Eiras; Jorge Luiz Colodette; Ana Márcia M. L. Carvalho

    2005-01-01

    Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC)(PO)DD, O(DC)(PO)DP, OD(PO)DD, OD(PO)DP, ODHT(PO)DD, ODHT(PO)DP, OA/D(PO)DD, OA/D(PO)DP, OAD(PO)DD and O(Ze)D(PO). Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to...

  12. The Planck Compact Source Catalogues

    OpenAIRE

    Lopez-Caniego, Marcos

    2015-01-01

    The Second Planck Catalogue of Compact Sources is a catalogue of sources observed over the entire sky at nine different frequencies between 30 and 857 GHz. It consists of Galactic and extragalactic objects detected in the Planck single-frequency full mission total intensity maps. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two sub·catalogues, the PCCS2 or PCCS2E, depending on their location ...

  13. Professional Windows Embedded Compact 7

    CERN Document Server

    Phung, Samuel; Joubert, Thierry; Hall, Mike

    2011-01-01

    Learn to program an array of customized devices and solutions As a compact, highly efficient, scalable operating system, Windows Embedded Compact 7 (WEC7) is one of the best options for developing a new generation of network-enabled, media-rich, and service-oriented devices. This in-depth resource takes you through the benefits and capabilities of WEC7 so that you can start using this performance development platform today. Divided into several major sections, the book begins with an introduction and then moves on to coverage of OS design, application development, advanced application developm

  14. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars

    CERN Document Server

    Bastien, Fabienne A; Pepper, Joshua

    2014-01-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50%...

  15. High Brightness Neutron Source for Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  16. Ultra-bright alkylated graphene quantum dots

    Science.gov (United States)

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-10-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy.Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The

  17. Intra-group Light in Hickson Compact Groups

    Science.gov (United States)

    Da Rocha, C.; Mendes de Oliveira, C.; Ziegler, B. L.

    We have analyzed the intra-group light component of 3 Hickson Compact Groups (HCG 79, HCG 88 and HCG 95) with detections in two of them: HCG 79, with 46±11% of the total B band luminosity and HCG 95 with 11±26%. HCG 88 had no component detected. This component is presumably due to tidally stripped stellar material trapped in the group potential and represents an efficient tool to determine the stage of dynamical evolution and to map its gravitational potential. To detect this low surface brightness structure we have applied the wavelet technique OV_WAV, which separates the different components of the image according to their spatial characteristic sizes.

  18. Intra-group Light in Hickson Compact Groups

    CERN Document Server

    Rocha, C D; Ziegler, B L; Rocha, Cristiano Da; Oliveira, Claudia Mendes de; Ziegler, Bodo L.

    2005-01-01

    We have analyzed the intra-group light component of 3 Hickson Compact Groups (HCG 79, HCG 88 and HCG 95) with detections in two of them: HCG 79, with $46\\pm11%$ of the total $B$ band luminosity and HCG 95 with $11\\pm26%$. HCG 88 had no component detected. This component is presumably due to tidally stripped stellar material trapped in the group potential and represents an efficient tool to determine the stage of dynamical evolution and to map its gravitational potential. To detect this low surface brightness structure we have applied the wavelet technique OV\\_WAV, which separates the different components of the image according to their spatial characteristic sizes.

  19. Tidal Tails in Interacting Galaxies: Formation of Compact Stellar Structures

    CERN Document Server

    Mullan, B; Konstantopoulos, I S; Bastian, N; Chandar, R; Durrell, P R; Elmegreen, D; English, J; Gallagher, S C; Gronwall, C; Hibbard, J E; Hunsberger, S; Johnson, K E; Kepley, A; Knierman, K; Koribalski, B; Lee, K H; Maybhate, A; Palma, C; Vacca, W D

    2009-01-01

    We have used V- and I- band images from the Hubble Space Telescope (HST) to identify compact stellar clusters within the tidal tails of twelve different interacting galaxies. The seventeen tails within our sample span a physical parameter space of HI/stellar masses, tail pressure and density through their diversity of tail lengths, optical brightnesses, mass ratios, HI column densities, stage on the Toomre sequence, and tail kinematics. Our preliminary findings in this study indicate that star cluster demographics of the tidal tail environment are compatible with the current understanding of star cluster formation in quiescent systems, possibly only needing changes in certain parameters or normalization of the Schechter cluster initial mass function (CIMF) to replicate what we observe in color-magnitude diagrams and a brightest absolute magnitude -- log N plot.

  20. JACKSON'S THEOREM FOR COMPACT GROUPS

    Institute of Scientific and Technical Information of China (English)

    H. Vaezi; S. F. Rzaev

    2002-01-01

    In this article we consider the generalized shift operator defined by(Sh.f)(g) = ∫Gf (tut-1g)dton compact group G and by help of this operator we define "Spherical" modulus of continuity. So we proveStechkin and Jackson type theorems.

  1. DNA compaction by nonbinding macromolecules

    NARCIS (Netherlands)

    Vries, de R.J.

    2012-01-01

    Compaction of DNA by nonbinding macromolecules such as uncharged flexible polymer chains and negatively charged globular proteins is thought to have various applications in biophysics, for example in the formation of a nucleoid structure in bacteria. A simple experimental model that has been very we

  2. Interpolation of compact non-linear operators

    OpenAIRE

    Bento AJG

    2000-01-01

    Let and be two Banach couples and let be a continuous map such that is a Lipschitz compact operator and is a Lipschitz operator. We prove that if is also compact or is continuously embedded in or is continuously embedded in , then is also a compact operator when and . We also investigate the behaviour of the measure of non-compactness under real interpolation and obtain best possible compactness results of Lions–Peetre type for non-linear operators. A two-sided compactness r...

  3. Dark and bright vortex solitons in electromagnetically induced transparent media

    International Nuclear Information System (INIS)

    We show that dark and bright vortex solitons can exist in three-state electromagnetically induced transparent media under some appropriate conditions. We also analyse the stability of the dark and bright vortex solitons. This work may provide other research opportunities in nonlinear optical experiments and may result in a substantial impact on technology

  4. Low dimensional neutron moderators for enhanced source brightness

    DEFF Research Database (Denmark)

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan;

    2014-01-01

    for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...

  5. Surface photometry of bulge dominated low surface brightness galaxies

    NARCIS (Netherlands)

    Beijersbergen, M; de Blok, WJG; van der Hulst, JM

    1999-01-01

    We present results of broad band BVRI observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median B b

  6. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    Energy Technology Data Exchange (ETDEWEB)

    Nangle, John [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simon, Joseph [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  7. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.; Butterfield, Karla [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  8. Lyman Alpha Mapping Project (LAMP) Brightness Maps

    Science.gov (United States)

    Retherford, Kurt D.; Gladstone, G.; Stern, S.; Egan, A. F.; Miles, P. F.; Parker, J. W.; Greathouse, T. K.; Davis, M. W.; Slater, D. C.; Kaufmann, D. E.; Versteeg, M. H.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2010-10-01

    The Lyman Alpha Mapping Project (LAMP) is an ultraviolet (UV) spectrograph on the Lunar Reconnaissance Orbiter (LRO) that is designed to map the lunar albedo at far-UV wavelengths. LAMP primarily measures interplanetary Hydrogen Lyman-alpha sky-glow and far-UV starlight reflected from the night-side lunar surface, including permanently shadowed regions (PSRs) near the poles. Dayside observations are also obtained. Brightness maps sorted by wavelength (including the Lyman-alpha wavelength of 121.6 nm) are reported for the polar regions, with a few regions of interest reported in more detail. LAMP's spectral range of 58 nm to 196 nm includes a water ice spectral feature near 160 nm, which provides a diagnostic tool for detecting water on the lunar surface that is complementary to recent discoveries using infrared and radio frequency techniques. Progress towards producing far-UV albedo maps and searching for water ice signatures will be reported. We'll discuss how LAMP data may address questions regarding how water is formed on the moon, transported through the lunar atmosphere, and deposited in the PSRs.

  9. Dark Skies, Bright Kids Year 6

    Science.gov (United States)

    Liss, Sandra; Troup, Nicholas William; Johnson, Kelsey E.; Barcos-Munoz, Loreto D.; Beaton, Rachael; Bittle, Lauren; Borish, Henry J.; Burkhardt, Andrew; Corby, Joanna; Dean, Janice; Hancock, Danielle; King, Jennie; Prager, Brian; Romero, Charles; Sokal, Kimberly R.; Stierwalt, Sabrina; Wenger, Trey; Zucker, Catherine

    2015-01-01

    Now entering our sixth year of operation, Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in central Virginia through fun, hands-on activities that introduce basic Astronomy concepts beyond Virginia's Standards of Learning. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.DSBK has amassed over 15,000 contact hours since 2009 and we continue to broaden our impact. One important step we have taken in the past year is to establish a graduate student led assessment program to identify and implement directed learning goals for DSBK outreach. The collection of student workbooks, observations, and volunteer surveys indicates broad scale success for the program both in terms of student learning and their perception of science. The data also reveal opportunities to improve our organizational and educational practices to maximize student achievement and overall volunteer satisfaction for DSBK's future clubs and outreach endeavors.

  10. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new mechanical electrodeposition technology was proposed, and nanocrystalline nickel deposit with bright and smooth surface was prepared in the bath without any additive agents. Unlike traditional methods, the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing. Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits, pinholes and nodules. Furthermore, comparing with the deposit prepared by traditional methods, the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm. Every diffraction peak’s intensity of the deposit was reduced, the preferential orientation degree of (200) decreased and those of (111) and (220) increased. The microhardness notably increased. The magnetic properties were also changed with decreased saturation magnetization and increased coercive force. It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.

  11. Antilensing: the bright side of voids.

    Science.gov (United States)

    Bolejko, Krzysztof; Clarkson, Chris; Maartens, Roy; Bacon, David; Meures, Nikolai; Beynon, Emma

    2013-01-11

    More than half of the volume of our Universe is occupied by cosmic voids. The lensing magnification effect from those underdense regions is generally thought to give a small dimming contribution: objects on the far side of a void are supposed to be observed as slightly smaller than if the void were not there, which together with conservation of surface brightness implies net reduction in photons received. This is predicted by the usual weak lensing integral of the density contrast along the line of sight. We show that this standard effect is swamped at low redshifts by a relativistic Doppler term that is typically neglected. Contrary to the usual expectation, objects on the far side of a void are brighter than they would be otherwise. Thus the local dynamics of matter in and near the void is crucial and is only captured by the full relativistic lensing convergence. There are also significant nonlinear corrections to the relativistic linear theory, which we show actually underpredicts the effect. We use exact solutions to estimate that these can be more than 20% for deep voids. This remains an important source of systematic errors for weak lensing density reconstruction in galaxy surveys and for supernovae observations, and may be the cause of the reported extra scatter of field supernovae located on the edge of voids compared to those in clusters. PMID:23383886

  12. Chromatic variations suppress suprathreshold brightness variations.

    Science.gov (United States)

    Kingdom, Frederick A A; Bell, Jason; Gheorghiu, Elena; Malkoc, Gokhan

    2010-01-01

    Most objects in natural scenes are suprathreshold in both color (chromatic) and luminance contrast. How salient is each dimension? We have developed a novel method employing a stimulus similar to that used by B. C. Regan and J. D. Mollon (1997) who studied the relative saliencies of the two chromatic cardinal directions. Our stimuli consist of left- and right-oblique modulations of color and/or luminance defined within a lattice of circles. In the "separated" condition, the two modulations were presented separately as forced-choice pairs, and the task was to indicate which was more salient. In the "combined" condition, the two orthogonal-in-orientation modulations were added, and the task was to indicate the more salient orientation. The ratio of color to luminance contrast at the PSE was calculated for both conditions. Across color directions, 48% more luminance contrast relative to color contrast was required to achieve a PSE in the "combined" compared to the "separated" condition. A second experiment showed that the PSE difference was due to the luminance being masked by the color, rather than due to superior color grouping. We conclude that suprathreshold brightness variations are masked by suprathreshold color variations. PMID:20884478

  13. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  14. The Los Alamos high-brightness photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, P.G.

    1991-01-01

    For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

  15. Compaction and relaxation of biofilms

    KAUST Repository

    Valladares Linares, R.

    2015-06-18

    Operation of membrane systems for water treatment can be seriously hampered by biofouling. A better characterization of biofilms in membrane systems and their impact on membrane performance may help to develop effective biofouling control strategies. The objective of this study was to determine the occurrence, extent and timescale of biofilm compaction and relaxation (decompaction), caused by permeate flux variations. The impact of permeate flux changes on biofilm thickness, structure and stiffness was investigated in situ and non-destructively with optical coherence tomography using membrane fouling monitors operated at a constant crossflow velocity of 0.1 m s−1 with permeate production. The permeate flux was varied sequentially from 20 to 60 and back to 20 L m−2 h−1. The study showed that the average biofilm thickness on the membrane decreased after elevating the permeate flux from 20 to 60 L m−2 h−1 while the biofilm thickness increased again after restoring the original flux of 20 L m−2 h−1, indicating the occurrence of biofilm compaction and relaxation. Within a few seconds after the flux change, the biofilm thickness was changed and stabilized, biofilm compaction occurred faster than the relaxation after restoring the original permeate flux. The initial biofilm parameters were not fully reinstated: the biofilm thickness was reduced by 21%, biofilm stiffness had increased and the hydraulic biofilm resistance was elevated by 16%. Biofilm thickness was related to the hydraulic biofilm resistance. Membrane performance losses are related to the biofilm thickness, density and morphology, which are influenced by (variations in) hydraulic conditions. A (temporarily) permeate flux increase caused biofilm compaction, together with membrane performance losses. The impact of biofilms on membrane performance can be influenced (increased and reduced) by operational parameters. The article shows that a (temporary) pressure increase leads to more

  16. Interpreting Central Surface Brightness and Color Profiles in Elliptical Galaxies

    Science.gov (United States)

    Silva, David R.; Wise, Michael W.

    1996-01-01

    Hubble Space Telescope imagery has revealed dust features in the central regions of many (50%--80%) nearby bright elliptical galaxies. If these features are an indication of an underlying smooth diffuse dust distribution, then the interpretation of central surface brightness and color profiles in elliptical galaxies becomes significantly more difficult. In this Letter, diagnostics for constraining the presence of such an underlying central dust distribution are presented. We show that easily detectable central color gradients and flattened central surface brightness profiles can be induced by even small amounts of smoothly distributed dust (~100 M⊙). Conversely, combinations of flat surface brightness profiles and flat color gradients or steep surface brightness profiles and steep color gradients are unlikely to be caused by dust. Taken as a whole, these results provide a simple observational tautology for constraining the existence of smooth diffuse dust distributions in the central regions of elliptical galaxies.

  17. Longitudinal Spatial Coherence Analysis Based on the Interpretation of the Fringes of Equal Thickness and its Practical Application for the Surface Profilometry%基于等厚干涉的轴向空间相干度分析及其在表面形状测量中的可行性探讨

    Institute of Scientific and Technical Information of China (English)

    段志辉; GolkherMark; 等

    2002-01-01

    Based on the interpretation for the fringes of equal thickness, we proposed the two dimensional longitudinal spatial coherence function. By manipulating the irradiance of an extended quasi-monochromatic spatially incoherent source with a spatial light modulator, we generated a special optical field that exhibits high coherence selectively for a specified location along the optical propagation axis and a specified inclination between the two mirrors. We proved the feasibility of the proposed principle for the application through measuring a real object with the standard step. In particular, we proposed a new phase shift technique without mechanical movement. The quantitative experimental proof of the principle is presented.%从等厚干涉的解释出发,推导出了二维空间的相干方程.基于空间相干方程,利用SLM产生了一个新的空间非相干光源.同时提出了新的相移方案,并结合这个新的相移方案,实现了轴向空间距离的探测和干涉条纹的相移.分析了空间方向角对相干方程的影响,并给出了实验验证.通过对非相干光源的参数和特定的空间距离以及空间方向角的匹配,重建了一个具有标准段差的实际物体的表面形状.为光学表面形状测量提供了新的思路.

  18. Brightness-equalized quantum dots: Engineering strategies derived from spectral trends

    Science.gov (United States)

    Smith, Andrew M.; Lim, Sung Jun

    2015-03-01

    Quantum dots are semiconductor nanocrystals that absorb and emit light at wavelengths tunable by the size of the crystal. Size-tuning provides access to a broad range of optical spectra, however it is fundamentally problematic for many applications because it leads to a large mismatch in absorption cross-section and fluorescence brightness across a series of colors. We have recently demonstrated engineering strategies to generate multicolor, extinction-matched, and brightness-matched quantum dots based on colloidal multi-domain core/shell structures. We use alloyed cores with composition-tunable bandgaps and finely adjust the domain size and electronic properties of the shell to precisely match both absorption cross-section and quantum yield. Using this strategy, it is possible to tune fluorescence wavelength, extinction, and quantum yield independently, vastly expanding the photophysical landscape of these materials. Moreover compared with conventional size-tuning strategies, this enables access to a wider spectral range with compact dimensions. The equalized optical properties translate from the ensemble level down to the single-molecule level, setting the stage for new possibilities in highly quantitative, multiplexed imaging in cells and tissue. However selection of appropriate structural parameters to generate specific optical properties is challenging without insight into the photophysics of these materials. Here we describe the evolution of the optical properties of alloyed cores during the shell growth process that provide new insights into general engineering strategies.

  19. Warm compaction powder metallurgy of Cu

    Institute of Scientific and Technical Information of China (English)

    NGAI Tungwai Leo; WANG Shang-lin; LI Yuan-yuan; ZHOU Zho-yao; CHEN Wei-ping

    2005-01-01

    A series of experiments were carried out using different admixed lubricant contents,different compaction pressures and temperatures in order to study the warm compaction of copper powder.Results show that too much admixed lubricant will lead to the squeeze out of the lubricant from the compact during the warm compaction processing of Cu powder.Results also show that blisters can be found in sintered samples that contain lubricant less than 0.15% (mass fraction).Optimal warm compaction parameters for producing high density powder metallurgy copper material are obtained.Compacts with green density of 8.6 g/cm3 and a sintered density of 8.83 g/cm3 can be produced by warm compacting the Cu powder,which contains 0.2% admixed lubricant,and is compacted at 145 ℃ with a pressure of 700 Mpa.

  20. Powder compaction in systems of bimodal distribution

    Science.gov (United States)

    Chattopadhyay, A. K.; Whittemore, O. J., Jr.

    1973-01-01

    The compaction of mixtures involving different particle sizes is discussed. The various stages of the compaction process include the rearrangement of particles, the filling of the interstices of the large particles by the smaller ones, and the change in particle size and shape upon further densification through the application of pressure. Experimental approaches and equipment used for compacting material are discussed together with the theoretical relations of the compacting process.

  1. Dark Skies, Bright Kids! Year 5

    Science.gov (United States)

    Prager, Brian; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Bittle, L.; Borish, H.; Burkhardt, A.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Graninger, D.; Lauck, T.; Liss, S.; Oza, A.; Peacock, S.; Romero, C.; Sokal, K. R.; Stierwalt, S.; Walker, L.; Wenger, T.; Zucker, C.

    2014-01-01

    Our public outreach group Dark Skies, Bright Kids! (DSBK) fosters science literacy in Virginia by bringing a hands-on approach to astronomy that engages children's natural excitement and curiosity. We are an entirely volunteer-run group based out of the Department of Astronomy at the University of Virginia and we enthusiastically utilize astronomy as a 'gateway science.' We create long-term relationships with students during an 8 to 10 week long, after-school astronomy club at under served elementary schools in neighboring counties, and we visited 3 different schools in 2013. Additionally, we organize and participate in science events throughout the community. The fifth year of DSBK was marked by surpassing 10,000 contact hours in Spring 2013 Semester and by ringing in the fall semester with our biggest, most successful star party to date. We hosted the Third Annual Central Virginia Star Party, free and open to the community to encourage families to enjoy astronomy together. Nearly four hundred people of all ages attended, double the number from previous years. Joining with local astronomical societies, we offered an enlightening and exciting night with resources rarely accessible to the public, such as an IR camera and a portable planetarium. With numerous telescopes pointed at the sky, and a beautifully clear night with views of the Milky Way, the International Space Station, and numerous meteors, the star party was a fantastic opportunity to introduce many of our guests to the natural wonders of our night sky and enjoy some of the darkest skies on the eastern seaboard.

  2. MAGNETIC FLUX SUPPLEMENT TO CORONAL BRIGHT POINTS

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China); Madjarska, Maria S., E-mail: z.huang@sdu.edu.cn [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

    2016-02-10

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the magnetic fluxes. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While magnetic cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak magnetic features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the magnetic activities responsible for the BP heating may involve small weak fields.

  3. Dark Skies, Bright Kids! Year 3

    Science.gov (United States)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  4. Dark Skies, Bright Kids! Year 4

    Science.gov (United States)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  5. Equationally Compact Acts : Coproducts / Peeter Normak

    Index Scriptorium Estoniae

    Normak, Peeter

    1998-01-01

    In this article equational compactness of acts and its generalizations are discussed. As equational compactness does not carry over to coproducts a slight generalization of c-equational campactness is introduced. It is proved that a coproduct of acts is c-equationally compact if and only if all components are c-equationally campact

  6. The Kolmogorov-Riesz compactness theorem

    CERN Document Server

    Hanche-Olsen, Harald

    2009-01-01

    We show that the Arzela-Ascoli theorem and Kolmogorov compactness theorem both are consequences of a simple lemma on compactness in metric spaces. Their relation to Helly's theorem is discussed. The paper contains a detailed discussion on the historical background of the Kolmogorov compactness theorem.

  7. Remnants of compact binary mergers

    CERN Document Server

    Domainko, W

    2006-01-01

    We investigate the long-term evolution and observability of remnants originating from the merger of compact binary systems and discuss the differences to supernova remnants. Compact binary mergers expel much smaller amounts of mass at much higher velocities, as compared to supernovae, which will affect the dynamical evolution of their remnants. The ejecta of mergers consist of very neutron rich nuclei. Some of these neutron rich nuclei will produce observational signatures in form of gamma ray lines during their decay. The composition of the ejecta might even give interesting constraints about the internal structure of the neutron star. We further discuss the possibility that merger remnants appear as recently discovered 'dark accelerators' which are extended TeV sources which lack emission in other bands.

  8. Compact heat exchangers modeling: Condensation

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Cascales, J.R.; Vera-Garcia, F. [Technical University of Cartagena, Thermal and Fluid Engineering Department, C/Dr. Fleming, s/n 30202 Cartagena, Murcia (Spain); Gonzalvez-Macia, J.; Corberan-Salvador, J.M. [Technical University of Valencia, Applied Thermodynamic Department, Valencia (Spain); Johnson, M.W.; Kohler, G.T. [Modine Manufacturing Company, Commercial Products Group, Racine, WI (United States)

    2010-01-15

    A model for the analysis of compact heat exchangers working as either evaporators or condensers is presented. This paper will focus exclusively on condensation modeling. The model is based on cell discretization of the heat exchanger in such a way that cells are analyzed following the path imposed by the refrigerant flowing through the tubes. It has been implemented in a robust code developed for assisting with the design of compact heat exchangers and refrigeration systems. These heat exchangers consist of serpentine fins that are brazed to multi-port tubes with internal microchannels. This paper also investigates a number of correlations used for the calculation of the refrigerant side heat transfer coefficient. They are evaluated comparing the predicted data with the experimental data. The working fluids used in the experiments are R134a and R410A, and the secondary fluid is air. The experimental facility is briefly described and some conclusions are finally drawn. (author)

  9. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  10. The lowest spatial frequency channel determines brightness perception.

    Science.gov (United States)

    Perna, A; Morrone, M C

    2007-05-01

    This study investigates the role played by individual spatial scales in determining the apparent brightness of greyscale patterns. We measured the perceived difference in brightness across an edge in the presence of notch filtering and high-pass filtering for two stimulus configurations, one that elicits the perception of transparency and one that appears opaque. For both stimulus configurations, the apparent brightness of the surfaces delimited by the border decreased monotonically with progressive (ideal) high-pass filtering, with a critical cut-off at 1 c/deg. Using two octave ideal notch filtering, the maximum detrimental effect on apparent brightness was observed at about 1c/deg. Critical frequencies for apparent brightness did not vary with contrast, viewing distance, or surface size, suggesting that apparent brightness is determined by the channel tuned at 1 c/deg. Modelling the data with the local energy model [Morrone, M. C., & Burr, D. C. (1988). Feature detection in human vision: a phase dependent energy model. Proceedings of the Royal Society (London), B235, 221-245] at 1c/deg confirmed the suggestion that this channel mediates apparent brightness for both opaque and transparent borders, with no need for pooling or integration across spatial channels. PMID:17395237

  11. Multipole structure of compact objects

    CERN Document Server

    Quevedo, Hernando

    2016-01-01

    We analyze the applications of general relativity in relativistic astrophysics in order to solve the problem of describing the geometric and physical properties of the interior and exterior gravitational and electromagnetic fields of compact objects. We focus on the interpretation of exact solutions of Einstein's equations in terms of their multipole moments structure. In view of the lack of physical interior solutions, we propose an alternative approach in which higher multipoles should be taken into account.

  12. Flexible Profile Compact Thermal Models

    OpenAIRE

    Sabry, M.-N.

    2005-01-01

    Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/5920) International audience Recent advances in Compact Thermal Models (CTM) have led to the emergence of a new concept allowing models to be created at any desired order of accuracy. In this paper, the concept will first be generalized to 3D parallelepiped boxes with both surface and/or volumetric heating. The second achievement is an adequate handling of heat transfer through side walls based on an ...

  13. Compact differences of composition operators

    CERN Document Server

    Heller, Katherine; Weir, Rachel J

    2010-01-01

    When $\\varphi$ and $\\psi$ are linear-fractional self-maps of the unit ball $B_N$ in ${\\mathbb C}^N$, $N\\geq 1$, we show that the difference $C_{\\varphi}-C_{\\psi}$ cannot be non-trivially compact on either the Hardy space $H^2(B_N)$ or any weighted Bergman space $A^2_{\\alpha}(B_N)$. Our arguments emphasize geometrical properties of the inducing maps $\\varphi$ and $\\psi$.

  14. Compact planar microwave blocking filters

    Science.gov (United States)

    U-Yen, Kongpop (Inventor); Wollack, Edward J. (Inventor)

    2012-01-01

    A compact planar microwave blocking filter includes a dielectric substrate and a plurality of filter unit elements disposed on the substrate. The filter unit elements are interconnected in a symmetrical series cascade with filter unit elements being organized in the series based on physical size. In the filter, a first filter unit element of the plurality of filter unit elements includes a low impedance open-ended line configured to reduce the shunt capacitance of the filter.

  15. Weak compactness of biharmonic maps

    Directory of Open Access Journals (Sweden)

    Shenzhou Zheng

    2012-10-01

    Full Text Available This article shows that if a sequence of weak solutions of a perturbed biharmonic map satisfies $Phi_ko 0$ in $(W^{2,2}^*$ and $u_kightharpoonup u$ weakly in $W^{2,2}$, then $u$ is a biharmonic map. In particular, we show that the space of biharmonic maps is sequentially compact under the weak-$W^{2,2}$ topology.

  16. Bright Laser-Driven Neutron Source Based on the Relativistic Transparency of Solids

    Science.gov (United States)

    Roth, M.; Jung, D.; Falk, K.; Guler, N.; Deppert, O.; Devlin, M.; Favalli, A.; Fernandez, J.; Gautier, D.; Geissel, M.; Haight, R.; Hamilton, C. E.; Hegelich, B. M.; Johnson, R. P.; Merrill, F.; Schaumann, G.; Schoenberg, K.; Schollmeier, M.; Shimada, T.; Taddeucci, T.; Tybo, J. L.; Wagner, F.; Wender, S. A.; Wilde, C. H.; Wurden, G. A.

    2013-01-01

    Neutrons are unique particles to probe samples in many fields of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers sufficient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to produce a forward peaked neutron flux with a record yield, on the order of 1010n/sr. We present results comparing the two acceleration mechanisms and the first short pulse laser generated neutron radiograph.

  17. Bright X-ray source from a laser-driven micro-plasma-waveguide

    CERN Document Server

    Yi, Longqing

    2016-01-01

    Bright tunable x-ray sources have a number of applications in basic science, medicine and industry. The most powerful sources are synchrotrons, where relativistic electrons are circling in giant storage rings. In parallel, compact laser-plasma x-ray sources are being developed. Owing to the rapid progress in laser technology, very high-contrast femtosecond laser pulses of relativistic intensities become available. These pulses allow for interaction with micro-structured solid-density plasma without destroying the structure by parasitic pre-pulses. The high-contrast laser pulses as well as the manufacturing of materials at micro- and nano-scales open a new realm of possibilities for laser interaction with photonic materials at the relativistic intensities. Here we demonstrate, via numerical simulations, that when coupling with a readily available 1.8 Joule laser, a micro-plasma-waveguide (MPW) may serve as a novel compact x-ray source. Electrons are extracted from the walls by the laser field and form a dense ...

  18. 76 FR 20044 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2011-04-11

    ... Federal Bureau of Investigation Meeting of the Compact Council for the National Crime Prevention and... this notice is to announce a meeting of the National Crime Prevention and Privacy Compact Council (Council) created by the National Crime Prevention and Privacy Compact Act of 1998 (Compact). Thus far,...

  19. Thixoforming of Stellite Powder Compacts

    Science.gov (United States)

    Hogg, S. C.; Atkinson, H. V.; Kapranos, P.

    2007-04-01

    Thixoforming involves processing metallic alloys in the semi-solid state. The process requires the microstructure to be spheroidal when part-solid and part-liquid i.e. to consist of solid spheroids surrounded by liquid. The aim of this work was to investigate whether powder compacts can be used as feedstock for thixoforming and whether the consolidating pressure in the thixoformer can be used to remove porosity from the compact. The powder compacts were made from stellite 6 and stellite 21 alloys, cobalt-based alloys widely used for e.g. manufacturing prostheses. Isothermal heat treatments of small samples in the consolidated state showed the optimum thixoforming temperature to be in the range 1340°C-1350°C for both materials. The alloys were thixoformed into graphite dies and flowed easily to fill the die. Porosity in the thixoformed components was lower than in the starting material. Hardness values at various positions along the radius of the thixoformed demonstrator component were above the specification for both alloys.

  20. Strings in compact cosmological spaces

    CERN Document Server

    Craps, Ben; Konechny, Anatoly

    2013-01-01

    We confront the problem of giving a fundamental definition to perturbative string theory in spacetimes with totally compact space (taken to be a torus for simplicity, though the nature of the problem is very general) and non-compact time. Due to backreaction induced by the presence of even a single string quantum, the usual formulation of perturbative string theory in a fixed classical background is infrared-divergent at all subleading orders in the string coupling, and needs to be amended. The problem can be seen as a closed string analogue of D0-brane recoil under an impact by closed strings (a situation displaying extremely similar infrared divergences). Inspired by the collective coordinate treatment of the D0-brane recoil, whereby the translational modes of the D0-brane are introduced as explicit dynamical variables in the path integral, we construct a similar formalism for the case of string-induced gravitational backreaction, in which the spatially uniform modes of the background fields on the compact ...

  1. Compaction Waves in Granular HMX

    Energy Technology Data Exchange (ETDEWEB)

    E. Kober; R. Menikoff

    1999-01-01

    Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.

  2. Compact Stellarator Path to DEMO

    Science.gov (United States)

    Lyon, J. F.

    2007-11-01

    Issues for a DEMO reactor are sustaining an ignited/high-Q plasma in steady state, avoiding disruptions and large variations in power flux to the wall, adequate confinement of thermal plasma and alpha-particles, control of a burning plasma, particle and power handling, etc. Compact stellarators have key advantages -- steady-state high-plasma-density operation without external current drive or disruptions, stability without a close conducting wall or active feedback systems, and low recirculating power -- in addition to moderate plasma aspect ratio, good confinement, and high-beta potential. The ARIES-CS study established that compact stellarators can be competitive with tokamaks as reactors. Many of the issues for a compact stellarator DEMO can be answered using results from large tokamaks, ITER D-T experiments and fusion materials, technology and component development programs, in addition to stellarators in operation, under construction or in development. However, a large next-generation stellarator will be needed to address some physics issues: size scaling and confinement at higher parameters, burning plasma issues, and operation with a strongly radiative divertor. Technology issues include simpler coils, structure, and divertor fabrication, and better cost information.

  3. Sky Brightness Measurements at Haleakala, 1955-2002

    Science.gov (United States)

    LaBonte, Barry

    2003-11-01

    Measurements of the brightness of the clear daytime sky at Haleakala, Maui are presented for the interval 1955 through 2002. The observations are made near the direction of the Sun, where forward scattering off aerosols dominates the sky brightness. The Haleakala summit at 3054 m is normally above the inversion layer. The Haleakala sky is dark; the observed brightness per airmass has a median of 10 millionths of the solar disk and a mode of 5 millionths, with Rayleigh scattering contributing 1 millionth. There is no demonstrable long-term trend in the data.

  4. Compact and energy saving magnet technology for particle accelerators

    International Nuclear Information System (INIS)

    Despite the fact that funding agencies and industrial users of particle accelerators get more and more alerted about costs of civil engineering, installation and operation, only little effort has been put into development of sustainable, energy and cost saving accelerator technology. In order to reduce the total-cost-of ownership of accelerator magnets, operating at high electrical power for twenty years or more, permanent magnet based Green Magnet technology has been developed at a consortium around Danfysik's R and D team. Together with our partners from ISA, Aarhus University, the Aarhus School of Engineering, the company Sintex and Aalborg University all obstacles in applying permanent magnet technology as e.g. thermal drift and inhomogeneities of magnetic fields have been overcome. The first Green Magnet has now been operated for more than half a year in an Accelerator Mass Spectrometry facility at the ETH in Zurich. The performance of this B=0.43T 90 deg. H-type bending magnet and the most recently builtB=1T, 30 deg. C-type Green Magnet for the synchrotron light source ASTRID2 at ISA in Aarhus will be presented. Danfysik also is designing, manufacturing and testing 60 compact magnet systems, developed at MAX-Lab for the new MAXIV 3.0 GeV synchrotron light source. In addition, 12 for the 1.5 GeV light source and another 12 for the new SOLARIS light source in Krakow, Poland are buying built. Up to a dozen or more magnet functions have been integrated into one yoke of these compact magnet systems, which makes the new MAXIV light sources compact, energy saving and at the same time very bright. Test results and design concepts of the new MAXIV and SOLARIS magnets will be presented. (author)

  5. Formation and evolution of blue compact dwarfs: the origin of their steep rotation curves

    Science.gov (United States)

    Watts, Adam; Bekki, Kenji

    2016-11-01

    The origin of the observed steep rotation curves of blue compact dwarf galaxies (BCDs) remains largely unexplained by theoretical models of BCD formation. We therefore investigate the rotation curves in BCDs formed from mergers between gas-rich dwarf irregular galaxies based on the results of numerical simulations for BCD formation. The principal results are as follows. The dark matter of merging dwarf irregulars undergoes a central concentration so that the central density can become up to six times higher than those of the initial dwarf irregulars. However, the more compact dark matter halo alone cannot reproduce the gradient differences observed between dwarf irregulars and BCDs. We provide further support that the central concentration of gas due to rapid gas transfer to the central regions of dwarf-dwarf mergers is responsible for the observed difference in rotation curve gradients. The BCDs with central gas concentration formed from merging can thus show steeply rising rotation curves in their central regions. Such gas concentration is also responsible for central starbursts of BCDs and the high central surface brightness and is consistent with previous BCD studies. We discuss the relationship between rotational velocity gradient and surface brightness, the dependence of BCD rotation curves on star formation threshold density, progenitor initial profile, interaction type, and merger mass ratio, as well as potential evolutionary links between dwarf irregulars, BCDs, and compact dwarf irregulars.

  6. Motion Analysis of Fiber Band in Compact Field of Compact Spinning

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The technological process of compact spinning and the compact procedure of fiber band in compact field are briefly illustrated. The motions of fiber band in compact field are discussed theoretically from which tilting angle of suction slot in profile tube, additional twists created by fiber band's rotating around its own axis and ultimate twists in compact yarn are deduced accordingly. The existence of additional twists is also verified through experiments.

  7. Visible Color and Photometry of Bright Materials on Vesta

    Science.gov (United States)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  8. Bright Prospect for the Polyester Industrial Filament Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Some large companies from Americaand Europe have constructed plantsin China or established long-termstable cooperation relationship withChinese enterprises. A bright devel-opment prospect has therefore beenbrought to the polyester industrial fila-ment sector in China.

  9. Are solar brightness variations faculae- or spot-dominated?

    CERN Document Server

    Shapiro, A I; Krivova, N A; Yeo, K L; Schmutz, W K

    2016-01-01

    Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to surface magnetic field. Independently, ground-based and spaceborne measurements suggest that Sun-like stars show a similar, but significantly broader pattern of photometric variability. To understand whether the broader pattern of stellar variations is consistent with the solar paradigm we assess relative contributions of faculae and spots to solar magnetically-driven brightness variability. We investigate how the solar brightness variability as well as its facular and spot contributions depend on the wavelength, timescale of variability, and position of the observer relative to the ecliptic plane. We perform calculations with the SATIRE model, which returns solar brightness with daily cadence from solar disc area coverages of various magnetic features. Moving the observer away from the ecliptic plane increases the amplitude of 11-year variability a...

  10. Hubble ultra deep field object surface brightness variation

    International Nuclear Information System (INIS)

    The technique of adjacent pixel brightness variation in log scale was applied to ultra deep field objects captured by the Hubble telescope. The local surface brightness fluctuation has a Gaussian-like distribution implying a random accretion of material, with collisions, as a random-walk motion. The larger fluctuation of log brightness in the mid to outer regions of some galaxies is consistent with the presence of dark matter. The absence of such fluctuation enhancement in two i-drop candidates at z ∼ 3 may mean that some dark matter is the result of nucleosynthesis in the evolution process. Large fluctuation in the B+V bands in contrast to the i+z band near the center in an i-drop candidate at z ∼ 3 was interpreted to be an AGN center. The distribution average shifts towards zero for more spiral galaxies, signifying the use of local surface brightness fluctuation distribution as a morphology parameter

  11. SMEX03 SSM/I Brightness Temperature Data, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  12. SMEX03 SSM/I Brightness Temperature Data, Georgia

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  13. Ultra High Brightness/Low Cost Fiber Coupled Packaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of the proposed effort is maximizing the brightness of fiber coupled laser diode pump sources at a minimum cost. The specific innovation proposed is to...

  14. Analytically derived conversion of spectral band radiance to brightness temperature

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., 44th Avenue, Burlington, MA 01803 (United States)], E-mail: lex@spectral.com

    2008-05-15

    Simple analytic expressions for brightness temperature have been derived in terms of band response function spectral moments. Accuracy measures are also derived. Application of these formulas to GOES-12 Sounder thermal infrared bands produces brightness temperature residuals between -5.0 and 2.5 mK for a 150-400 K temperature range. The magnitude of residuals for the five ASTER Radiometer thermal infrared bands over the same temperature range is less than 0.22 mK.

  15. Night Sky Brightness and Light Pollution in Comunidad de Madrid

    OpenAIRE

    Zamorano Calvo, Jaime; Sánchez de Miguel, Alejandro; Gómez Castaño, José; Ocaña González, Francisco; Gallego Maestro, Jesús; Pila Díez, Berenice; Nievas Rosillo, Miguel; Tapia Ayuga, Carlos; Fernández Domínguez, Alberto; Pascual Ramírez, Sergio

    2013-01-01

    Preliminary results of a study of the night sky background brightness around the city of Madrid using Sky Quality Meter (SQM) photometers are presented. Data-retrieval methodology includes an automatic procedure to measure from a moving vehicle which allows to speed up the data gathering. The night sky brightness, an astronomical quality parameter that accounts for luminous flux from the sky, is closely related with the light pollution. The map with the spatial distribution of the night s...

  16. Supercontinuum generation with bright and dark solitons in optical fibers

    CERN Document Server

    Milián, Carles; Kudlinski, Alexandre; Skryabin, Dmitry V

    2016-01-01

    We study numerically and experimentally supercontinuum generation in optical fibers with dark and bright solitons simultaneously contributing into the spectral broadening and dispersive wave generation. We report a novel type of weak trapped radiation arising due to interaction of bright solitons with the dark soliton background. This radiation expresses itself as two pulses with the continuously shifting spectra constituting the short and long wavelength limits of the continuum. Our theoretical and experimental results are in good agreement.

  17. Facial Expression Recognition using Entropy and Brightness Features

    OpenAIRE

    Khan, Rizwan Ahmed; Meyer, Alexandre; Konik, Hubert; Bouakaz, Saïda

    2011-01-01

    International audience This paper proposes a novel framework for universal facial expression recognition. The framework is based on two sets of features extracted from the face image: entropy and brightness. First, saliency maps are obtained by state-of-the-art saliency detection algorithm i.e. "frequencytuned salient region detection". Then only localized salient facial regions from saliency maps are processed to extract entropy and brightness features. To validate the performance of sali...

  18. Millimeter-wave brightness temperatures of military vehicles

    Science.gov (United States)

    Nemarich, Joseph; Cassidy, Thomas W.; Shiner, R.; Agravante, Hiroshi H.; Dixon, David; Moffa, Philip; Quon, Bill H.; Yujiri, Larry; Dahlstrom, R.

    1999-07-01

    Millimeter wave (MMW) radiometers operating at 97 and 140 GHz were used to obtain passive MMW images and brightness temperatures of military vehicles at various altitudes and depression angles. The line-scanning radiometer system used for the measurements is described, and several passive MMW images are presented. The upper-bound MMW brightness temperatures of a number of different types of vehicles in an open area were determined and shown to have similar values at various depression angles.

  19. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    OpenAIRE

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their abs...

  20. Relating basic properties of bright early-type dwarf galaxies to their location in Abell 901/902

    CERN Document Server

    Barazza, F D; Gray, M E; Jogee, S; Balogh, M; McIntosh, D H; Bacon, D; Barden, M; Bell, E F; Boehm, A; Caldwell, J A R; Haeussler, B; Heiderman, A; Heymans, C; van Kampen, K Jahnke E; Lane, K; Marinova, I; Meisenheimer, K; Peng, C Y; Sánchez, S F; Taylor, A; Wisotzki, L; Zheng, X

    2009-01-01

    We present a study of the population of bright early-type dwarf galaxies in the multiple-cluster system Abell 901/902. We use data from the STAGES survey and COMBO-17 to investigate the relation between the color and structural properties of the dwarfs and their location in the cluster. The definition of the dwarf sample is based on the central surface brightness and includes galaxies in the luminosity range -16 >= M_B <~-19 mag. Using a fit to the color magnitude relation of the dwarfs, our sample is divided into a red and blue subsample. We find a color-density relation in the projected radial distribution of the dwarf sample: at the same luminosity dwarfs with redder colors are located closer to the cluster centers than their bluer counterparts. Furthermore, the redder dwarfs are on average more compact and rounder than the bluer dwarfs. These findings are consistent with theoretical expectations assuming that bright early-type dwarfs are the remnants of transformed late-type disk galaxies involving pro...

  1. Synthesizing SMOS Zero-Baselines with Aquarius Brightness Temperature Simulator

    Science.gov (United States)

    Colliander, A.; Dinnat, E.; Le Vine, D.; Kainulainen, J.

    2012-01-01

    SMOS [1] and Aquarius [2] are ESA and NASA missions, respectively, to make L-band measurements from the Low Earth Orbit. SMOS makes passive measurements whereas Aquarius measures both passive and active. SMOS was launched in November 2009 and Aquarius in June 2011.The scientific objectives of the missions are overlapping: both missions aim at mapping the global Sea Surface Salinity (SSS). Additionally, SMOS mission produces soil moisture product (however, Aquarius data will eventually be used for retrieving soil moisture too). The consistency of the brightness temperature observations made by the two instruments is essential for long-term studies of SSS and soil moisture. For resolving the consistency, the calibration of the instruments is the key. The basis of the SMOS brightness temperature level is the measurements performed with the so-called zero-baselines [3]; SMOS employs an interferometric measurement technique which forms a brightness temperature image from several baselines constructed by combination of multiple receivers in an array; zero-length baseline defines the overall brightness temperature level. The basis of the Aquarius brightness temperature level is resolved from the brightness temperature simulator combined with ancillary data such as antenna patterns and environmental models [4]. Consistency between the SMOS zero-baseline measurements and the simulator output would provide a robust basis for establishing the overall comparability of the missions.

  2. Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

    Institute of Scientific and Technical Information of China (English)

    LIU Jinsong

    2001-01-01

    A numerical analysis of the dynamical evolution of bright screening-photovoltaic (SP) spatial solitons in biased photovoltaic-photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low-intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high-intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

  3. Image Contrast Enhancement for Brightness Preservation Based on Dynamic Stretching

    Directory of Open Access Journals (Sweden)

    M.A. Rahman

    2015-08-01

    Full Text Available Histogram equalization is an efficient process often employed in consumer electronic systems for image contrast enhancement. In addition to an increase in contrast, it is also required to preserve the mean brightness of an image in order to convey the true scene information to the viewer. A conventional approach is to separate the image into sub-images and then process independently by histogram equalization towards a modified profile. However, due to the variations in image contents, the histogram separation threshold greatly influences the level of shift in mean brightness with respect to the uniform histogram in the equalization process. Therefore, the choice of a proper threshold, to separate the input image into sub-images, is very critical in order to preserve the mean brightness of the output image. In this research work, a dynamic range stretching approach is adopted to reduce the shift in output image mean brightness. Moreover, the computationally efficient golden section search algorithm is applied to obtain a proper separation into sub-images to preserve the mean brightness. Experiments were carried out on a large number of color images of natural scenes. Results, as compared to current available approaches, showed that the proposed method performed satisfactorily in terms of mean brightness preservation and enhancement in image contrast.

  4. Compact Radiometers Expand Climate Knowledge

    Science.gov (United States)

    2010-01-01

    To gain a better understanding of Earth's water, energy, and carbon cycles, NASA plans to embark on the Soil Moisture Active and Passive mission in 2015. To prepare, Goddard Space Flight Center provided Small Business Innovation Research (SBIR) funding to ProSensing Inc., of Amherst, Massachusetts, to develop a compact ultrastable radiometer for sea surface salinity and soil moisture mapping. ProSensing incorporated small, low-cost, high-performance elements into just a few circuit boards and now offers two lightweight radiometers commercially. Government research agencies, university research groups, and large corporations around the world are using the devices for mapping soil moisture, ocean salinity, and wind speed.

  5. The Cooling of Compact Stars

    CERN Document Server

    Page, D; Weber, F; Page, Dany; Geppert, Ulrich; Weber, Fridolin

    2005-01-01

    The cooling of a compact star depends very sensitively on the state of dense matter at supranuclear densities, which essentially controls the neutrino emission, as well as on the structure of the stellar outer layers which control the photon emission. Open issues concern the hyperon population, the presence of meson condensates, superfluidity and superconductivity, and the transition of confined hadronic matter to quark matter. This paper describes these issues and presents cooling calculations based on a broad collection of equations of state for neutron star matter and strange matter. These results are tested against the body of observed cooling data.

  6. Porewater chemistry in compacted bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Muurinen, A.; Lehikoinen, J. [VTT Chemical Technology, Espoo (Finland)

    1999-03-01

    In this study, the porewater chemistry in compacted bentonite, considered as an engineered barrier in the repository of spent fuel, has been studied in interaction experiments. Many parameters, like the composition and density of bentonite, composition of the solution, bentonite-to-water ratio (B/W), surrounding conditions and experimental time have been varied in the experiments. At the end of the interaction the equilibrating solution, the porewaters squeezed out of the bentonite samples, and bentonites themselves were analyzed to give information for the interpretation and modelling of the interaction. Equilibrium modelling was performed with the HYDRAQL/CE computer code 33 refs.

  7. Compact objects in Horndeski gravity

    Science.gov (United States)

    Silva, Hector O.; Maselli, Andrea; Minamitsuji, Masato; Berti, Emanuele

    2016-04-01

    Horndeski gravity holds a special position as the most general extension of Einstein’s theory of general relativity (GR) with a single scalar degree of freedom and second-order field equations. Because of these features, Horndeski gravity is an attractive phenomenological playground to investigate the consequences of modifications of GR in cosmology and astrophysics. We present a review of the progress made so far in the study of compact objects (black holes (BHs) and neutron stars (NSs)) within Horndeski gravity. In particular, we review our recent work on slowly rotating BHs and present some new results on slowly rotating NSs.

  8. Compact inertial confinement multireactor concepts

    International Nuclear Information System (INIS)

    Inertial confinement fusion (ICF) commercial-applications plant-optimum driver pulse repetition rates may exceed reactor pulse-repetition-rate capabilities. Thus, more than one reactor may be required for low-cost production of electric power, process heat, fissionable fuels, etc., in ICF plants. Substantial savings in expensive reactor containment cells and blankets can be realized by placing more than one reactor in a cell and by surrounding more than one reactor cavity with a single blanket system. There are also some potential disadvantages associated with close coupling in compact multicavity blankets and multireactor cells. Tradeoffs associated with several scenarios have been studied

  9. New charged anisotropic compact models

    Science.gov (United States)

    Kileba Matondo, D.; Maharaj, S. D.

    2016-07-01

    We find new exact solutions to the Einstein-Maxwell field equations which are relevant in the description of highly compact stellar objects. The relativistic star is charged and anisotropic with a quark equation of state. Exact solutions of the field equations are found in terms of elementary functions. It is interesting to note that we regain earlier quark models with uncharged and charged matter distributions. A physical analysis indicates that the matter distributions are well behaved and regular throughout the stellar structure. A range of stellar masses are generated for particular parameter values in the electric field. In particular the observed mass for a binary pulsar is regained.

  10. Compact Hermitian Young Projection Operators

    CERN Document Server

    Alcock-Zeilinger, Judith

    2016-01-01

    In this paper, we describe a compact and practical algorithm to construct Hermitian Young projection operators for irreducible representations of the special unitary group SU(N), and discuss why ordinary Young projection operators are unsuitable for physics applications. The proof of this construction algorithm uses the iterative method described by Keppeler and Sj\\"odahl. We further show that Hermitian Young projection operators share desirable properties with Young tableaux, namely a nested hierarchy when "adding a particle". We end by exhibiting the enormous advantage of the Hermitian Young projection operators constructed in this paper over those given by Keppeler and Sj\\"odahl.

  11. Self-compacting concrete (SCC)

    DEFF Research Database (Denmark)

    Geiker, Mette Rica

    2008-01-01

    In many aspects Self-Compacting Concrete (SCC, “Self-Consolidating Concrete” in North America) can be considered the concrete of the future. SCC is a family of tailored concretes with special engineered properties in the fresh state. SCC flows into the formwork and around even complicated...... freedom in structural design. The present Chapter describes selected properties of SCC. The properties and use of SCC are illustrated through a few case histories and future trends are briefly described. The Chapter concludes with a list of sources of further information....

  12. Compact Visualisation of Video Summaries

    Directory of Open Access Journals (Sweden)

    Janko Ćalić

    2007-01-01

    Full Text Available This paper presents a system for compact and intuitive video summarisation aimed at both high-end professional production environments and small-screen portable devices. To represent large amounts of information in the form of a video key-frame summary, this paper studies the narrative grammar of comics, and using its universal and intuitive rules, lays out visual summaries in an efficient and user-centered way. In addition, the system exploits visual attention modelling and rapid serial visual presentation to generate highly compact summaries on mobile devices. A robust real-time algorithm for key-frame extraction is presented. The system ranks importance of key-frame sizes in the final layout by balancing the dominant visual representability and discovery of unanticipated content utilising a specific cost function and an unsupervised robust spectral clustering technique. A final layout is created using an optimisation algorithm based on dynamic programming. Algorithm efficiency and robustness are demonstrated by comparing the results with a manually labelled ground truth and with optimal panelling solutions.

  13. The Planck Compact Source Catalogues

    Science.gov (United States)

    Lopez-Caniego, Marcos

    2015-12-01

    The Second Planck Catalogue of Compact Sources is a catalogue of sources observed over the entire sky at nine different frequencies between 30 and 857 GHz. It consists of Galactic and extragalactic objects detected in the Planck single-frequency full mission total intensity maps. Compact sources detected in the lower frequency channels are assigned to the PCCS2, while at higher frequencies they are assigned to one of two sub·catalogues, the PCCS2 or PCCS2E, depending on their location on the sky. The PCCS2 covers most of the sky and can be used to produce subsamples at higher reliabilities than the target 80% integral reliability of the catalogue. The PCCS2E contains sources located in certain regions where the complex background makes it difficult to quantify the reliability of the detections. Both the PCCS2 and PCCS2E include polarization measurements, in the form of polarized flux densities, or upper limits, and orientation angles for all seven polarization-sensitive Planck channels.

  14. Brittle and compaction creep in porous sandstone

    Science.gov (United States)

    Heap, Michael; Brantut, Nicolas; Baud, Patrick; Meredith, Philip

    2015-04-01

    Strain localisation in the Earth's crust occurs at all scales, from the fracture of grains at the microscale to crustal-scale faulting. Over the last fifty years, laboratory rock deformation studies have exposed the variety of deformation mechanisms and failure modes of rock. Broadly speaking, rock failure can be described as either dilatant (brittle) or compactive. While dilatant failure in porous sandstones is manifest as shear fracturing, their failure in the compactant regime can be characterised by either distributed cataclastic flow or the formation of localised compaction bands. To better understand the time-dependency of strain localisation (shear fracturing and compaction band growth), we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (porosity = 24%) under a constant stress (creep) in the dilatant and compactive regimes, with particular focus on time-dependent compaction band formation in the compactive regime. Our experiments show that inelastic strain accumulates at a constant stress in the brittle and compactive regimes leading to the development of shear fractures and compaction bands, respectively. While creep in the dilatant regime is characterised by an increase in porosity and, ultimately, an acceleration in axial strain to shear failure (as observed in previous studies), compaction creep is characterised by a reduction in porosity and a gradual deceleration in axial strain. The overall deceleration in axial strain, AE activity, and porosity change during creep compaction is punctuated by excursions interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased, although the inelastic strain required for a compaction band remains constant over strain rates spanning several orders of magnitude. We find that, despite the large differences in strain rate and growth rate

  15. VSOP monitoring of the compact BL Lac object AO 0235+164

    CERN Document Server

    Frey, S; Gabuzda, D C; Salter, C J; Altschüler, D R; Perillat, P; Aller, M F; Aller, H D; Hirabayashi, H; Davis, M M

    2005-01-01

    In 1999, the highly compact and variable BL Lac object AO 0235+164 was identified as the highest brightness temperature active galactic nucleus observed with the VLBI Space Observatory Programme (VSOP), with T_B > 5.8 x 10^{13} K. The sub-milliarcsecond radio structure of this source has been studied with dual-frequency (1.6 and 5 GHz), polarization-sensitive VSOP observations during 2001 and 2002. Here we present the results of this monitoring campaign. At the time of these observations, the source was weakly polarized and characterized by a radio core that is clearly resolved on space-ground baselines.

  16. Discovery of Nine Intermediate Redshift Compact Quiescent Galaxies in the Sloan Digital Sky Survey

    CERN Document Server

    Damjanov, Ivana; Hwang, Ho Seong; Geller, Margaret J

    2013-01-01

    We identify nine galaxies with dynamical masses of M_dyn>10^10 M_sol as photometric point sources, but with redshifts between z=0.2 and z=0.6, in the Sloan Digital Sky Survey (SDSS) spectro-photometric database. All nine galaxies have archival Hubble Space Telescope (HST) images. Surface brightness profile fitting confirms that all nine galaxies are extremely compact (with circularized half-light radii between 0.4 and 6.6 kpc and the median value of 0.74 kpc) for their velocity dispersion (1101 galaxies and the other eight objects follow the high-redshift dynamical size-mass relation.

  17. X-ray properties of G308.3-1.4 and its central compact object

    OpenAIRE

    Seo, K. A.; Hui, C. Y.; Huang, R. H. H.; Trepl, L.; Lu, T.-N.; Kong, A. K. H.; Walter, F. M.

    2012-01-01

    We present a short Chandra observation that confirms a previous unidentified extended X-ray source, G308.3-1.4, as a new supernova remnant (SNR) in the Milky Way. Apart from identifying its SNR nature, a bright X-ray point source has also been discovered at the geometrical center. Its X-ray spectral properties are similar to those of a particular class of neutron star known as central compact objects (CCOs). On the other hand, the optical properties of this counterpart suggests it to be a lat...

  18. Incoherent transient radio emission from stellar-mass compact objects in the SKA era

    CERN Document Server

    Corbel, S; Fender, R P; Gallo, E; Maccarone, T J; O'Brien, T J; Paragi, Z; Rupen, M P; Rushton, A P; Sabatini, S; Sivakoff, G R; Strader, J; Woud, P A

    2015-01-01

    The universal link between the processes of accretion and ejection leads to the formation of jets and outflows around accreting compact objects. Incoherent synchrotron emission from these outflows can be observed from a wide range of accreting binaries, including black holes, neutron stars, and white dwarfs. Monitoring the evolution of the radio emission during their sporadic outbursts provides important insights into the launching of jets, and, when coupled with the behaviour of the source at shorter wavelengths, probes the underlying connection with the accretion process. Radio observations can also probe the impact of jets/outflows (including other explosive events such as magnetar giant flares) on the ambient medium, quantifying their kinetic feedback. The high sensitivity of the SKA will open up new parameter space, enabling the monitoring of accreting stellar-mass compact objects from their bright, Eddington-limited outburst states down to the lowest-luminosity quiescent levels, whose intrinsic faintnes...

  19. Compact approach to fusion power reactors

    International Nuclear Information System (INIS)

    The potential of the Reversed-Field Pinch (RFP) for development into an efficient, compact, copper-coil fusion reactor has been quantified by comprehensive parametric tradeoff studies. These compact systems promise to be competitive in size, power density, and cost to alternative energy sources. Conceptual engineering designs that largely substantiate these promising results have since been completed. This 1000-MWe(net) design is described along with a detailed rationale and physics/technology assessment for the compact approach to fusion

  20. Self Compacting Concrete And Its Properties

    OpenAIRE

    Mahesh, S.

    2014-01-01

    Self-compacting concrete (SCC), which flows under its own weight and doesn’t require any external vibration for compaction, has revolutionized concrete placement. Such concrete should have relatively low yield value to ensure high flow ability, a moderate viscosity to resists segregation and bleeding and must maintain its homogeneity during transportation, placing and curing to ensure adequate structural performance and long term durability. Self-compacting concrete (SCC) ca...

  1. Nonlinear Viscoelastic Compaction in Sedimentary Basins

    CERN Document Server

    Yang, Xin-She

    2010-01-01

    In the mathematical modelling of sediment compaction and porous media flow, the rheological behaviour of sediments is typically modelled in terms of a nonlinear relationship between effective pressure $p_e$ and porosity $\\phi$, that is $p_e=p_e(\\phi)$. The compaction law is essentially a poroelastic one. However, viscous compaction due to pressure solution becomes important at larger depths and causes this relationship to become more akin to a viscous rheology. A generalised viscoelastic compaction model of Maxwell type is formulated, and different styles of nonlinear behaviour are asymptotically analysed and compared in this paper.

  2. On compact generation of some deformed surfaces

    CERN Document Server

    Lowen, Wendy

    2012-01-01

    We obtain a theorem which allows to prove compact generation of derived categories of Grothendieck categories, based upon certain coverings by localizations. This theorem follows from an application of Rouquier's cocovering theorem in the triangulated context, and it implies Neeman's result on compact generation of quasi-compact separated schemes. We investigate applications of our theorem to non-commutative deformations of such schemes. In general there are obstructions, but for instance our approach yields compact generation of all first order deformations of quasi-projective surfaces.

  3. CANDELS+3D-HST: compact SFGs at z~2-3, the progenitors of the first quiescent galaxies

    CERN Document Server

    Barro, G; Perez-Gonzalez, P G; Pacifici, C; Trump, J R; Koo, D C; Wuyts, S; Guo, Y; Bell, E; Dekel, A; Porter, L; Primack, J; Ferguson, H; Ashby, M; Caputi, K; Ceverino, D; Croton, D; Fazio, G; Giavalisco, M; Hsu, L; Kocevski, D; Koekemoer, A; Kurczynski, P; Kollipara, P; Lee, J; McIntosh, D; McGrath, E; Moody, C; Somerville, R; Papovich, C; Salvato, M; Santini, P; Williams, C C; Willner, S; Zolotov, A

    2013-01-01

    We analyze the star-forming and structural properties of 45 massive (log(M/Msun)>10) compact star-forming galaxies (SFGs) at 2compact quiescent galaxies at z~2. The optical/NIR and far-IR Spitzer/Herschel colors indicate that most compact SFGs are heavily obscured. Nearly half (47%) host an X-ray bright AGN. In contrast, only about 10% of other massive galaxies at that time host AGNs. Compact SFGs have centrally-concentrated light profiles and spheroidal morphologies similar to quiescent galaxies, and are thus strikingly different from other SFGs. Most compact SFGs lie either within the SFR-M main sequence (65%) or below (30%), on the expected evolutionary path towards quiescent galaxies. These results show conclusively that galaxies become more compact before they lose their gas and dust, quenching star formation. Using extensive HST photometry from CANDELS and grism spectroscopy from the 3D-HST survey, we model their stellar populations with either expon...

  4. Bright artificial light subsensitizes a central muscarinic mechanism.

    Science.gov (United States)

    Dilsaver, S C; Majchrzak, M J

    1987-12-14

    Supersensitivity of a muscarinic mechanism is implicated in the pathophysiology of depression. Bright artificial light is efficacious in the treatment of Seasonal Affective Disorder (SAD). We studied the effect of constant bright light (11,500 lux) on the sensitivity of adult, male rats to oxotremorine, 1.5 mg/kg ip, using a repeated measures design. Oxotremorine challenges were proceeded by the injection of methylscopolamine, 1 mg/kg ip, by 30 minutes. Temperature was telemetrically measured every 10 minutes for 120 minutes starting 10 minutes after the injection of oxotremorine. Prior to and after 7 continuous days of exposure to bright light, the sample exhibited a hypothermic response of 2.50 +/- 0.48 degrees C (mean +/- SEM) and 0.29 +/- 0.31 degrees C (mean +/- SEM), respectively (p less than 0.0014). All 7 animals exhibited blunting to the thermic response to oxotremorine. Bright light also blocked the capacity of amitriptyline to supersensitize a central muscarinic mechanism. Exposure to light at an intensity of 300 lux for 7 days had no effect on the thermic response to oxotremorine. These data are consistent with the hypotheses that the biology of depression involves supersensitivity of central muscarinic mechanisms and that the effects of bright artificial light are not the consequence of shifting circadian rhythms. PMID:3695799

  5. The night sky brightness at Potsdam-Babelsberg

    CERN Document Server

    Puschnig, Johannes; Posch, Thomas; Schwarz, Robert

    2013-01-01

    We analyze the results of a 2 years (2011--2012) time series of night sky photometry performed at the Leibniz Institute for Astrophysics in Potsdam (AIP). This observatory is located on top of a hill ("Babelsberg"), 22\\,km to the southwest of the center of Berlin. The measurements have been performed with a Unihedron Sky Quality Meter. We find night sky brightness values ranging from 16.5 to 20.3 mag$_{\\rm SQM}$ arcsec$^{-2}$; the latter (best) value corresponds to 4.7 times the natural zenithal night sky brightness. We discuss the influence of clouds, of the Moon and other factors on the night sky brightness. With respect to the influence of the Moon, it turns out that Potsdam-Babelsberg, despite its proximity to Berlin, still shows a circalunar periodicity of the night sky brightness, although it is much weaker than naturally. The light-pollution-enhancing effect of clouds dominates the night sky brightness by far. Overcast nights with light pollution (up to 16.5 mag$_{\\rm SQM}$ arcsec$^{-2}$) are brighter ...

  6. PROFFIT: Analysis of X-ray surface-brightness profiles

    Science.gov (United States)

    Eckert, Dominique

    2016-08-01

    PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

  7. Night sky brightness at San Pedro Martir Observatory

    CERN Document Server

    Plauchu-Frayn, I; Colorado, E; Herrera, J; Cordova, A; Cesena, U; Avila, F

    2016-01-01

    We present optical UBVRI zenith night sky brightness measurements collected on eighteen nights during 2013--2016 and SQM measurements obtained daily over twenty months during 2014--2016 at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN-SPM) in Mexico. The UBVRI data is based upon CCD images obtained with the 0.84m and 2.12m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 mag/square arcsec, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend im...

  8. Compact torus experiments and theory

    International Nuclear Information System (INIS)

    Two types of compact toroids have been studied: spheromaks and field-reversed configurations (FRC). Spheromaks, which contain both toroidal and poloidal fields, have been formed with a magnetized coaxial injector and trapped in both prolate and oblate flux conservers. As expected from theory, the prolate configuration always tilts, but the oblate configuration can be made stable even in the presence of a guide field. Observations include 150μs lifetimes, approx. 1014 cm-3, and a decrease of field fluctuations by a factor of 100 at the time of complete reconnection. Theoretical studies of the FRC (no toroidal field) have been compared with the results of two field-reversed theta-pinches, FRX-A and FRX-B

  9. Spiral Inflector For Compact Cyclotron

    CERN Document Server

    Karamysheva, G A

    2004-01-01

    Compact cyclotron for explosives detection by nuclear resonance absorption of γ-rays in nitrogen is under development [1] Cyclotron will be equipped with the external ion source. The injection system consists of a double-drift beam bunching system, a spiral inflector, beam diagnostics, focusing and adjustment elements [2]. The spiral inflector for ion bending from axial to median plane is used. Computer model of spiral inflector for the Customs cyclotron is developed. 3D electrostatic field calculations of the designed inflector are performed. Calculated electric field map and magnetic field map of the cyclotron [3] are used for beam dynamic simulations. Numeric simulations are carried out for 500 particles using code for calculation of particle dynamics by integration of differential equations in Cartesian coordinate system written in MATLAB. Direct Coulomb particle-to-particle method is used to take into account space-charge effects.

  10. A Compact UWB Diversity Antenna

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2014-01-01

    Full Text Available A compact printed ultrawideband (UWB diversity antenna with a size of 30 mm × 36 mm operating at a frequency range of 3.1–10.6 GHz is proposed. The antenna is composed of two semielliptical monopoles fed by two microstrip lines. Two semicircular slots, two rectangular slots, and one stub are introduced in the ground plane to adjust the impedance bandwidth of the antenna and improve the isolation between two feeding ports. The simulated and measured results show that impedance bandwidth of the proposed antenna can cover the whole UWB band with a good isolation of < −15 dB. The radiation patterns, peak antenna gain, and envelope correlation coefficient are also measured and discussed. The measured results show that the proposed antenna can be a good candidate for some portable MIMO/diversity UWB applications.

  11. Compact K-edge densitometer

    International Nuclear Information System (INIS)

    Los Alamos National Laboratory has designed, built, and is currently testing a compact K-edge densitometer for use by International Atomic Energy Agency (IAEA) inspectors. The unit, which can easily be moved from one location to another within a facility, is positioned outside a glovebox with the body of the instrument inserted into the glove. A fixture inside the glovebox fits around the body and positions a sample holder. A hand-held high-purity germanium detector powered by a battery pack and a Davidson portable multichannel analyzer (MCA) is used to measure the transmission through plutonium nitrate solutions at E/sub Y/ = 121.1 and 122.2 keV. The Davidson MCA is programmed to lead the user through the measurement procedure and perform all the data analyses. The instrument is currently installed at the Safeguards Analytical Laboratory, where IAEA personnel are evaluating its accuracy, ease of operation, and safety. 5 references, 5 figures, 5 tables

  12. Studies of accelerated compact toruses

    International Nuclear Information System (INIS)

    In an earlier publication we considered acceleration of plasma rings (Compact Torus). Several possible accelerator configurations were suggested and the possibility of focusing the accelerated rings was discussed. In this paper we consider one scheme, acceleration of a ring between coaxial electrodes by a B/sub theta/ field as in a coaxial rail-gun. If the electrodes are conical, a ring accelerated towards the apex of the cone undergoes self-similar compression (focusing) during acceleration. Because the allowable acceleration force, F/sub a/ = kappaU/sub m//R where (kappa -2, the accelerating distance for conical electrodes is considerably shortened over that required for coaxial electrodes. In either case, however, since the accelerating flux can expand as the ring moves, most of the accelerating field energy can be converted into kinetic energy of the ring leading to high efficiency

  13. Gravitational waves from compact objects

    Institute of Scientific and Technical Information of China (English)

    José Antonio de Freitas Pacheco

    2010-01-01

    Large ground-based laser beam interferometers are presently in operation both in the USA (LIGO) and in Europe (VIRGO) and potential sources that might be detected by these instruments are revisited. The present generation of detectors does not have a sensitivity high enough to probe a significant volume of the universe and,consequently, predicted event rates are very low. The planned advanced generation of interferometers will probably be able to detect, for the first time, a gravitational signal. Advanced LIGO and EGO instruments are expected to detect few (some): binary coalescences consisting of either two neutron stars, two black holes or a neutron star and a black hole. In space, the sensitivity of the planned LISA spacecraft constellation will allow the detection of the gravitational signals, even within a "pessimistic" range of possible signals, produced during the capture of compact objects by supermassive black holes, at a rate of a few tens per year.

  14. Compact RFID Enabled Moisture Sensor

    Directory of Open Access Journals (Sweden)

    U. H. Khan

    2016-09-01

    Full Text Available This research proposes a novel, low-cost RFID tag sensor antenna implemented using commercially available Kodak photo-paper. The aim of this paper is to investigate the possibility of stable, RFID centric communication under varying moisture levels. Variation in the frequency response of the RFID tag in presence of moisture is used to detect different moisture levels. Combination of unique jaw shaped contours and T-matching network is used for impedance matching which results in compact size and minimal ink consumption. Proposed tag is 1.4 × 9.4 cm2 in size and shows optimum results for various moisture levels upto 45% in FCC band with a bore sight read range of 12.1 m.

  15. Compact Digital High Voltage Charger

    CERN Document Server

    Li, Ge

    2005-01-01

    The operation of classical resonant circuit developed for the pulse energizing is investigated. The HV pulse or generator is very compact by a soft switching circuit made up of IGBT working at over 30 kHZ. The frequencies of macro pulses andμpulses can be arbitrarily tuned below resonant frequency to digitalize the HV pulse power. Theμpulses can also be connected by filter circuit to get the HVDC power. The circuit topology is given and its novel control logic is analyzed by flowchart. The circuit is part of a system consisting of a AC or DC LV power supply, a pulse transformer, the pulse generator implemented by LV capacitor and leakage inductance of the transformer, a HV DC or pulse power supply and the charged HV capacitor of the modulators.

  16. New Evidence for a Black Hole in the Compact Binary Cygnus X-3

    CERN Document Server

    Shrader, Chris; Shaposhnikov, Nikolai

    2010-01-01

    The bright and highly variable X-ray and radio source known as Cygnus X-3 was among the first X-ray sources discovered, yet it remains in many ways an enigma. Its known to consist of a massive, Wolf-Rayet primary in an extremely tight orbit with a compact object. Yet one of the most basic of parameters - the mass of the compact object - is not known. Nor is it even clear whether its is a neutron star or a black hole. In this Paper we present our analysis of the broad-band high-energy continua covering a substantial range in luminosity and spectral morphology. We apply these results to a recently identified scaling relationship which has been demonstrated to provide reliable estimates of the compact object mass in a number of accretion powered binaries. This analysis leads us to conclude that the compact object in Cygnus X-3 has a mass greater than $4.2M_\\odot$ thus clearly indicative of a black hole and as such resolving a long-standing issue. The full range of uncertainty in our analysis and from using a ran...

  17. Bright and Not-So-Bright Prospects for Women in Physics in China-Beijing

    Science.gov (United States)

    Wu, Ling-An; Yang, Zhongqin; Ma, Wanyun

    2009-04-01

    Science in China-Beijing is enjoying a healthy increase in funding year by year, so the prospects for physicists are also bright. However, employment discrimination against women, formerly unthinkable, is becoming more and more explicit as the country evolves toward a market economy. Some recruitment notices bluntly state that only men will be considered, or impose restrictions upon potential female candidates. Female associate professors in many institutions are forced to retire at age 55, compared with 60 for men. This double-pinching discrimination against both younger and older women threatens to lead to a "pincer" effect, more serious than the "scissors" effect. Indeed, the ratio of senior-level women physicists in general has dropped significantly in recent years in China. Ironically, the number of female students applying for graduate studies is on the rise, as it is becoming increasingly difficult for them to compete with men in the job market with just an undergraduate degree. The Chinese Physical Society has made certain efforts to promote the image of women physicists, but it will take time and effort to reverse the trend.

  18. High-brightness ultra-cold metastable neon-beam

    CERN Document Server

    Shimizu, Fujio

    2015-01-01

    This paper presents detailed characteristics of an ultra-cold bright metastable neon atomic beam which we have been using for atom-interferometric applications. The basis of the device is an atomic beam released from a magneto-optical trap (MOT) which is operated with a high intensity trapping laser, high magnetic quadrupole field, and large laser detuining. Mainly due to the complex structure of three dimensional magnetic field and laser beams, a bright small spot of atoms is formed near the center of the quadrupole magnetic field under an appropriate operating condition. We obtained the minimum trap diameter of 50 micron meter, the atomic density nearly 10^{13}cm^{-3}, and the atomic temperature slightly less than the Doppler limited temperature of 200 micro-K. By releasing trapped atoms we obtained an bright cold atomic beam which is not far from the collision limited atomic density.

  19. The Spectroscopic Properties of Bright Extragalactic Planetary Nebulae

    CERN Document Server

    Richer, M G

    2006-01-01

    The properties of bright extragalactic planetary nebulae are reviewed based upon the results of low and high resolution spectroscopy. It is argued that bright extragalactic planetary nebulae from galaxies (or subsystems) with and without star formation have different distributions of central star temperature and ionization structure. As regards the chemical compositions, oxygen and neon are generally found to be unchanged as a result of the evolution of the stellar progenitors. Nitrogen enrichment may occur as a result of the evolution of the progenitors of bright planetary nebulae in all stellar populations, though this enrichment may be (more) random in old stellar populations. Helium abundances appear to be influenced by the chemical evolution of the host galaxy, with planetary nebulae in dwarf spheroidals having systematically elevated abundances. Neither the age nor the metallicity of the progenitor stellar population has a strong effect upon the kinematics observed for nebular shells. Both the range of ...

  20. The ASAS-SN Bright Supernova Catalog $-$ II. 2015

    CERN Document Server

    Holoien, T W -S; Stanek, K Z; Kochanek, C S; Shappee, B J; Prieto, J L; Dong, Subo; Brimacombe, J; Bishop, D W; Basu, U; Beacom, J F; Bersier, D; Chen, Ping; Danilet, A B; Falco, E; Godoy-Rivera, D; Goss, N; Pojmanski, G; Simonian, G V; Skowron, D M; Thompson, Todd A; Woźniak, P R; Avíla, C G; Bock, G; Carballo, J -L G; Conseil, E; Contreras, C; Cruz, I; andújar, J M F; Guo, Zhen; Hsiao, E Y; Kiyota, S; Koff, R A; Krannich, G; Madore, B F; Marples, P; Masi, G; Morrell, N; Monard, L A G; Munoz-Mateos, J C; Nicholls, B; Nicolas, J; Wagner, R M; Wiethoff, W S

    2016-01-01

    This manuscript presents information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during 2015, its second full year of operations. The same information is presented for bright ($m_V\\leq17$), spectroscopically confirmed supernovae discovered by other sources in 2015. As with the first ASAS-SN bright supernova catalog, we also present redshifts and near-UV through IR magnitudes for all supernova host galaxies in both samples. Combined with our previous catalog, this work comprises a complete catalog of 455 supernovae from multiple professional and amateur sources, allowing for population studies that were previously impossible. This is the second of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

  1. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    CERN Document Server

    Karachentsev, I D; Zilch, T; Blauensteiner, M; Elvov, M; Hochleitner, P; Hubl, B; Kerschhuber, G; Küppers, S; Neyer, F; Pölzl, R; Remmel, P; Schneider, O; Sparenberg, R; Trulson, U; Willems, G; Ziegler, H

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M_B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26.1 mag/sq arcsec. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC,891 and NGC,2683.

  2. New low surface brightness dwarf galaxies detected around nearby spirals

    Science.gov (United States)

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.; Willems, G.; Ziegler, H.

    2015-10-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26ṃ1/□″. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC891 and NGC2683.

  3. Automated Detection and Tracking of Solar Magnetic Bright Points

    CERN Document Server

    Crockett, P J; Mathioudakis, M; Keenan, F P

    2009-01-01

    Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm employing data taken with the Swedish Solar Telescope (SST), reveal that ~90% of MBPs within a 75"x 75" field of view are detected.

  4. RF Manipulations for Higher Brightness LHC-Type Beams

    CERN Document Server

    Damerau, H; Gilardoni, S; Hancock, S

    2013-01-01

    In order to increase the transverse brightness of beams for the LHC, ever more complicated RF manipulations have been proposed in the PS machine to reduce the intensity demands per PS batch on the upstream PS Booster. Several schemes based on cascades of batch compression, bunch merging, as well as the more routine bunch splitting have been successfully commissioned and higher brightness beams have been delivered to the downstream accelerators for measurement. Despite all this complexity, longitudinal and transverse beam quality are well preserved. In addition, to profit fully from the brightness of all four PS Booster rings, the injection of twice 4 bunches into harmonic 9 buckets in the PS has been made operational as an alternative to the usual double-batch transfer of 4 + 2 bunches into harmonic 7. This paper summarizes the new beam production schemes, their implementation in the PS low-level RF system and the experimental results..

  5. Dark-bright ring solitons in Bose-Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Stockhofe, J; Schmelcher, P [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Kevrekidis, P G [Department of Mathematics and Statistics, University of Massachusetts, Amherst MA 01003-4515 (United States); Frantzeskakis, D J, E-mail: jstockho@physnet.uni-hamburg.de, E-mail: kevrekid@math.umass.edu [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece)

    2011-10-14

    We study dark-bright (DB) ring solitons in two-component Bose-Einstein condensates. In the limit of large densities of the dark component, we describe the soliton dynamics by means of an equation of motion for the ring radius. The presence of the bright, 'filling' species is demonstrated to have a stabilizing effect on the ring dark soliton. Near the linear limit, we discuss the symmetry-breaking bifurcations of DB soliton stripes and vortex-bright soliton clusters from the DB ring and relate the stabilizing effect of filling to changes in the bifurcation diagram. Finally, we show that the stabilization by means of a second component is not limited to the radially symmetric structures, but can also be observed in a cross-like DB soliton configuration. (fast track communication)

  6. Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

    Science.gov (United States)

    Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

    2016-01-01

    Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

  7. Exploring the Multi-Wavelength, Low Surface Brightness Universe

    CERN Document Server

    Brunner, R J; Gal, R R; Mahabal, A A; Odewahn, S C

    2000-01-01

    Our current understanding of the low surface brightness universe is quite incomplete, not only in the optical, but also in other wavelength regimes. As a demonstration of the type of science which is facilitated by a virtual observatory, we have undertaken a project utilizing both images and catalogs to explore the multi-wavelength, low surface brightness universe. Here, we present some initial results of this project. Our techniques are complimentary to normal data reduction pipeline techniques in that we focus on the diffuse emission that is ignored or removed by more traditional algorithms. This requires a spatial filtering which must account for objects of interest, in addition to observational artifacts (e.g., bright stellar halos). With this work we are exploring the intersection of the catalog and image domains in order to maximize the scientific information we can extract from the federation of large survey data.

  8. Faint Dwarf Galaxies in Hickson Compact Group 90

    Science.gov (United States)

    Ordenes-Briceño, Yasna; Taylor, Matthew A.; Puzia, Thomas H.; Muñoz, Roberto P.; Eigenthaler, Paul; Georgiev, Iskren Y.; Goudfrooij, Paul; Hilker, Michael; Lançon, Ariane; Mamon, Gary; Mieske, Steffen; Miller, Bryan W.; Peng, Eric W.; Sánchez-Janssen, Rubén

    2016-08-01

    We report the discovery of a very diverse set of five low-surface brightness (LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in deep U- and I-band images obtained with VLT/VIMOS. These are the first LSB dwarf galaxy candidates found in a compact group of galaxies. We measure spheroid half-light radii in the range 0.7 ≲ reff/kpc ≲ 1.5 with luminosities of -11.65 ≲ MU ≲ -9.42 and -12.79 ≲ MI ≲ -10.58 mag, corresponding to a color range of (U - I)0 ≃ 1.1 - 2.2 mag and surface brightness levels of μU ≃ 28.1 mag/arcsec2 and μI ≃ 27.4 mag/arcsec2. Their colours and luminosities are consistent with a diverse set of stellar population properties. Assuming solar and 0.02 Z⊙ metallicities we obtain stellar masses in the range M_*|_{Z_odot } ˜eq 10^{5.7-6.3} M_{odot } and M_*|_{0.02 Z_odot } ˜eq 10^{6.3-8} M_{odot }. Three dwarfs are older than 1 Gyr, while the other two significantly bluer dwarfs are younger than ˜2 Gyr at any mass/metallicity combination. Altogether, the new LSB dwarf galaxy candidates share properties with dwarf galaxies found throughout the Local Volume and in nearby galaxy clusters such as Fornax. We find a pair of candidates with ˜2 kpc projected separation, which may represent one of the closest dwarf galaxy pairs found. We also find a nucleated dwarf candidate, with a nucleus size of reff ≃ 46 - 63 pc and magnitude MU, 0 = -7.42 mag and (U - I)0 = 1.51 mag, which is consistent with a nuclear stellar disc with a stellar mass in the range 104.9 - 6.5 M⊙.

  9. The possible origin of facular brightness in the solar atmosphere

    Science.gov (United States)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  10. Bright and dark excitons in semiconductor carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Tretiak, Sergei [Los Alamos National Laboratory

    2008-01-01

    We report electronic structure calculations of finite-length semiconducting carbon nanotubes using the time dependent density functional theory (TD-DFT) and the time dependent Hartree Fock (TD-HF) approach coupled with semiempirical AM1 and ZINDO Hamiltonians. We specifically focus on the energy splitting, relative ordering, and localization properties of the optically active (bright) and optically forbidden (dark) states from the lowest excitonic band of the nanotubes. These excitonic states are very important in competing radiative and non-radiative processes in these systems. Our analysis of excitonic transition density matrices demonstrates that pure DFT functionals overdelocalize excitons making an electron-hole pair unbound; consequently, excitonic features are not presented in this method. In contrast, the pure HF and A111 calculations overbind excitons inaccurately predicting the lowest energy state as a bright exciton. Changing AM1 with ZINDO Hamiltonian in TD-HF calculations, predicts the bright exciton as the second state after the dark one. However, in contrast to AM1 calculations, the diameter dependence of the excitation energies obtained by ZINDO does not follow the experimental trends. Finally, the TD-DFT approach incorporating hybrid functions with a moderate portion of the long-range HF exchange, such as B3LYP, has the most generality and predictive capacity providing a sufficiently accurate description of excitonic structure in finite-size nanotubes. These methods characterize four important lower exciton bands. The lowest state is dark, the upper band is bright, and the two other dark and nearly degenerate excitons lie in-between. Although the calculated energy splittings between the lowest dark and the bright excitons are relatively large ({approx}0.1 eV), the dense excitonic manifold below the bright exciton allows for fast non-radiative relaxation leasing to the fast population of the lowest dark exciton. This rationalizes the low

  11. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    Mikko Paavo Tulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  12. Do low surface brightness galaxies have dense disks?

    CERN Document Server

    Saburova, A S

    2010-01-01

    The disk masses of four low surface brightness galaxies (LSB) were estimated using marginal gravitational stability criterion and the stellar velocity dispersion data which were taken from Pizzella et al., 2008 [1]. The constructed mass models appear to be close to the models of maximal disk. The results show that the disks of LSB galaxies may be significantly more massive than it is usually accepted from their brightnesses. In this case their surface densities and masses appear to be rather typical for normal spirals. Otherwise, unlike the disks of many spiral galaxies, the LSB disks are dynamically overheated.

  13. Absolute brightness temperature measurements at 2.1-mm wavelength

    Science.gov (United States)

    Ulich, B. L.

    1974-01-01

    Absolute measurements of the brightness temperatures of the Sun, new Moon, Venus, Mars, Jupiter, Saturn, and Uranus, and of the flux density of DR21 at 2.1-mm wavelength are reported. Relative measurements at 3.5-mm wavelength are also preented which resolve the absolute calibration discrepancy between The University of Texas 16-ft radio telescope and the Aerospace Corporation 15-ft antenna. The use of the bright planets and DR21 as absolute calibration sources at millimeter wavelengths is discussed in the light of recent observations.

  14. The brightness variations of Comet Halley at large heliocentric distances

    Science.gov (United States)

    Flammer, K. R.; Jackson, B.; Houpis, H. L. F.; Mendis, D. A.

    1986-01-01

    The reasons for the intrinsic brightness variations of up to 500 percent on time scales as short as a few hours detected by Sekanina (1984) in Comet Halley between October 1982 and February 1984 are discussed. It is shown that solar wind-modulated electrostatic dust blowoff from the night side of the comet is consistent with the observed brightness variations. The variations coincide with the encounter of high-speed streams with the comet. The stream's propagation time to the comet and the sun's rotation during this transit were used to locate the stream origin on the coronal surface, and the results are shown.

  15. Laser ion source for high brightness heavy ion beam

    Science.gov (United States)

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. However we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. In 2014, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory. Now most of all the solid based heavy ions are being provided from the laser ion source for regular operation.

  16. High-brightness displays in integrated weapon sight systems

    Science.gov (United States)

    Edwards, Tim; Hogan, Tim

    2014-06-01

    In the past several years Kopin has demonstrated the ability to provide ultra-high brightness, low power display solutions in VGA, SVGA, SXGA and 2k x 2k display formats. This paper will review various approaches for integrating high brightness overlay displays with existing direct view rifle sights and augmenting their precision aiming and targeting capability. Examples of overlay display systems solutions will be presented and discussed. This paper will review significant capability enhancements that are possible when augmenting the real-world as seen through a rifle sight with other soldier system equipment including laser range finders, ballistic computers and sensor systems.

  17. Quantification of the compactibility of pharmaceutical powders

    DEFF Research Database (Denmark)

    Sonnergaard, Jørn

    2006-01-01

    The purpose of this study is to investigate and to quantify the compactibility of pharmaceutical powders by a simple linear relationship between the diametral compressive strength of tablets and the applied compaction pressure. The mechanical strength of the tablets is characterized as the crushing...

  18. The classification of 2-compact groups

    DEFF Research Database (Denmark)

    K. S. Andersen, Kasper; Grodal, Jesper

    2009-01-01

    with Moeller and Viruel for p odd, this establishes the full classification of p-compact groups, stating that, up to isomorphism, there is a one-to-one correspondence between connected p-compact groups and root data over the p-adic integers. As a consequence we prove the maximal torus conjecture, giving a one...

  19. Interpolation of bilinear operators and compactness

    CERN Document Server

    da Silva, Eduardo Brandani

    2012-01-01

    The behavior of bilinear operators acting on interpolation of Banach spaces for the $\\rho$ method in relation to the compactness is analyzed. Similar results of Lions-Peetre, Hayakawa and Person's compactness theorems are obtained for the bilinear case and the $\\rho$ method.

  20. Compact Process Development at Babcock & Wilcox

    Energy Technology Data Exchange (ETDEWEB)

    Eric Shaber; Jeffrey Phillips

    2012-03-01

    Multiple process approaches have been used historically to manufacture cylindrical nuclear fuel compacts. Scale-up of fuel compacting was required for the Next Generation Nuclear Plant (NGNP) project to achieve an economically viable automated production process capable of providing a minimum of 10 compacts/minute with high production yields. In addition, the scale-up effort was required to achieve matrix density equivalent to baseline historical production processes, and allow compacting at fuel packing fractions up to 46% by volume. The scale-up approach of jet milling, fluid-bed overcoating, and hot-press compacting adopted in the U.S. Advanced Gas Reactor (AGR) Fuel Development Program involves significant paradigm shifts to capitalize on distinct advantages in simplicity, yield, and elimination of mixed waste. A series of compaction trials have been completed to optimize compaction conditions of time, temperature, and forming pressure using natural uranium oxycarbide (NUCO) fuel at packing fractions exceeding 46% by volume. Results from these trials are included. The scale-up effort is nearing completion with the process installed and operable using nuclear fuel materials. Final process testing is in progress to certify the process for manufacture of qualification test fuel compacts in 2012.

  1. Computing Decoupled Residuals for Compact Disc Players

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle;

    2006-01-01

    a pair of residuals generated by Compact Disc Player. However, these residuals depend on the performance of position servos in the Compact Disc Player. In other publications of the same authors a pair of decoupled residuals is derived. However, the computation of these alternative residuals has been...

  2. Relatively Compact Sets on Abstract Wiener Space

    Institute of Scientific and Technical Information of China (English)

    Xi Cheng ZHANG

    2005-01-01

    In this note, we obtain a sufficient and necessary condition for a set in an abstract Wiener space (X, H,μ) to be relatively compact in L2(X, μ). Meanwhile, we give a sufficient condition for relative compactness in Lp(X, μ) for p > 1. We also provide an example of Da Prato-Malliavin-Nualart to show the result.

  3. Feature Based Control of Compact Disc Players

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh

    Two servo control loops are used to keep the Optical Pick-up Unit focused and radially on the information track of the Compact Disc. These control servos have problems handling surface faults on the Compact Disc. In this Ph.D thesis a method is proposed to improve the handling of these surface...

  4. Harmonic maps between compact Hermitian manifolds

    Institute of Scientific and Technical Information of China (English)

    LIU KeFeng; YANG XiaoKui

    2008-01-01

    In this paper, we generalize the Bochner-Kodaira formulas to the case of Hermitian com-plex (possibly non-holomorphic) vector bundles over compact Hermitian (possibly non-Kahler) mani-folds. As applications, we get the complex analyticity of harmonic maps between compact Hermitian manifolds.

  5. Harmonic maps between compact Hermitian manifolds

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we generalize the Bochner-Kodaira formulas to the case of Hermitian com- plex (possibly non-holomorphic) vector bundles over compact Hermitian (possibly non-K¨ahler) mani- folds. As applications, we get the complex analyticity of harmonic maps between compact Hermitian manifolds.

  6. A compact lightweight aerosol spectrometer probe (CLASP)

    NARCIS (Netherlands)

    Hill, M.K.; Brooks, B.J.; Norris, S.J.; Smith, M.H.; Brooks, I.M.; Leeuw, G. de

    2008-01-01

    The Compact Lightweight Aerosol Spectrometer Probe (CLASP) is an optical particle spectrometer capable of measuring size-resolved particle concentrations in 16 user-defined size bins spanning diameters in the range 0.24 < D < 18.5 μm at a rate of 10 Hz. The combination of its compact nature and ligh

  7. Induced corepresentations of locally compact quantum groups

    OpenAIRE

    Kustermans, Johan

    2000-01-01

    We introduce the construction of induced corepresentations in the setting of locally compact quantum groups and prove that the resulting induced corepresentations are unitary under some mild integrability condition. We also establish a quantum analogue of the classical bijective correspondence between quasi-invariant measures and certain measures on the larger locally compact group.

  8. Rate type isotach compaction of consolidated sandstone

    NARCIS (Netherlands)

    Waal, J.A. de; Thienen-Visser, K. van; Pruiksma, J.P.

    2015-01-01

    Laboratory experiments on samples from a consolidated sandstone reservoir are presented that demonstrate rate type compaction behaviour similar to that observed on unconsolidated sands and soils. Such rate type behaviour can have large consequences for reservoir compaction, surface subsidence and in

  9. DYNAMIC COMPACTION OF PURE COPPER POWDER USING PULSED MAGNETIC FORCE

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The compaction of pure Cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.

  10. WEIGHTED COMPACT SCHEME FOR SHOCK CAPTURING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new class of finite difference schemes--the weighted compact schemes are proposed. According to the idea of the WENO schemes, the weighted compact scheme is constructed by a combination of the approximations of derivatives on candidate stencils with properly assigned weights so that the non-oscillatory property is achieved when discontinuities appear. The primitive function reconstruction method of ENO schemes is applied to obtain the conservative form of the weighted compact scheme. This new scheme not only preserves the characteristic of standard compact schemes and achieves high order accuracy and high resolution using a compact stencil,but also can accurately capture shock waves and discontinuities without oscillation, Numerical examples show that the new scheme is very promising and successful.``

  11. Height formation of bright points observed by IRIS in Mg II line wings during flux emergence

    Science.gov (United States)

    Grubecka, M.; Schmieder, B.; Berlicki, A.; Heinzel, P.; Dalmasse, K.; Mein, P.

    2016-09-01

    Context. A flux emergence in the active region AR 111850 was observed on September 24, 2013 with the Interface Region Imaging Spectrograph (IRIS). Many bright points are associated with the new emerging flux and show enhancement brightening in the UV spectra. Aims: The aim of this work is to compute the altitude formation of the compact bright points (CBs) observed in Mg II lines in the context of searching Ellerman bombs (EBs). Methods: IRIS provided two large dense rasters of spectra in Mg II h and k lines, Mg II triplet, C II and Si IV lines covering all the active region and slit jaws in the two bandpasses (1400 Å and 2796 Å) starting at 11:44 UT and 15:39 UT, and lasting 20 min each. Synthetic profiles of Mg II and Hα lines are computed with non-local thermodynamic equlibrium (NLTE) radiative transfer treatment in 1D solar atmosphere model including a hotspot region defined by three parameters: temperature, altitude, and width. Results: Within the two IRIS rasters, 74 CBs are detected in the far wings of the Mg II lines (at +/-1 Å and 3.5 Å). Around 10% of CBs have a signature in Si IV and CII. NLTE models with a hotspot located in the low atmosphere were found to fit a sample of Mg II profiles in CBs. The Hα profiles computed with these Mg II CB models are consistent with typical EB profiles observed from ground based telescopes e.g. THEMIS. A 2D NLTE modelling of fibrils (canopy) demonstrates that the Mg II line centres can be significantly affected but not the peaks and the wings of Mg II lines. Conclusions: We conclude that the bright points observed in Mg II lines can be formed in an extended domain of altitudes in the photosphere and/or the chromosphere (400 to 750 km). Our results are consistent with the theory of heating by Joule dissipation in the atmosphere produced by magnetic field reconnection during flux emergence.

  12. Investigation of compressibility and compactibility parameters of roller compacted Theophylline and its binary mixtures.

    Science.gov (United States)

    Hadžović, Ervina; Betz, Gabriele; Hadžidedić, Seherzada; El-Arini, Silvia Kocova; Leuenberger, Hans

    2011-09-15

    Roller compaction is a dry granulation method which results in tablets with inferior tensile strength comparing to direct compaction. The effect of roller compaction on compressibility and compactibility of tablets prepared from Theophylline anhydrate powder, Theophylline anhydrate fine powder and Theophylline monohydrate was investigated by measuring tensile strength of tablets as well as calculating compressibility and compactibility parameters by Leuenberger equation. The tablets under the same conditions were prepared by direct compaction and roller compaction. The binary mixtures of Theophylline anhydrate powder, Theophylline anhydrate fine powder, Theophylline monohydrate and microcrystalline cellulose were prepared in order to determine the optimal ratio of active material and excipients which delivers a sufficient mechanical strength of tablets. Tensile strength of MCC tablets and compactibility parameters calculated by Leuenberger equation after roller compaction was significantly decreased, while THAP, THAFP and THMO tablets showed only a minor reduction in compactibility and compressibility. Adding MCC to a mixture with Theophylline showed that the right choice and ratio of excipients can enable a sufficient mechanical strength of the tablets after roller compaction. PMID:21704142

  13. The Host in Blue Compact Galaxies: Structural Properties and Scaling Relations

    CERN Document Server

    Amorín, Ricardo; Muñoz-Tuñón, C; Cairós, L M

    2009-01-01

    We have characterized the underlying stellar host in a sample of 28 blue compact galaxies (BCGs), by fitting their 2D light distributions. Their structural parameters were related with galaxy properties such as colours and gas content. These properties were also compared with those of other galaxy types. All the BCG hosts but one show low Sersic indexes (0.5 =1.11$\\pm$0.74 kpc, and mean surface brightness = 22.59$\\pm$0.68 mag arcsec$^{-2}$. Host effective radii scale linearly with their luminosity, while n and $\\mu_{\\rm e}$ do not. In addition, host colours and structural parameters are not linearly correlated. Overall,the flux enhancement caused by the starburst is about 0.8 mag while their B-R colours decrease by about 0.2 mag. Galaxies with more luminous and extended hosts show larger and luminous starburst components. BCG hosts show B-R=0.95$\\pm$0.26 in median. Overall, BCG hosts are more compact (by a factor ~2) and have higher central surface brightnesses (by about ~2 mag) than dIs and most dEs. BCG ho...

  14. Intra-Group Light in Hickson Compact Groups - A Wavelet Approach

    CERN Document Server

    Rocha, C D; Ziegler, B L; Rocha, Cristiano Da; Oliveira, Claudia Mendes de; Ziegler, Bodo L.

    2005-01-01

    A diffuse component of intra-group light can be observed in compact groups of galaxies. This component is presumably due to stellar material tidally stripped from the member galaxies of the group, which gets trapped in the group potential. It represents an efficient tool for the determination of the stage of dynamical evolution of such structures and for mapping the gravitational potential of the group. Detecting this kind of low surface brightness structure (about 1% above the sky level) is a difficult task, which is subject to many problems like the modeling of stars and galaxy and sky subtraction. To overcome these problems, we apply a new method, the wavelet technique OV\\_WAV, with which these low surface brightness structures can be revealed and analyzed by separating different components according to their spatial characteristic sizes (allowing the study of the point sources, galaxies and diffuse envelope separately). We have analyzed 3 of the of the Hickson Compact Groups Catalogue (HCG 79, HCG 88 and ...

  15. Variations in the Fe mineralogy of bright Martian soil

    Science.gov (United States)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  16. Bright-dark incoherently coupled photovoltaic soliton pair

    Institute of Scientific and Technical Information of China (English)

    Hou Chun-Feng; Pei Yan-Bo; Zhou Zhong-Xiang; Sun Xiu-Dong

    2005-01-01

    The coupling between two mutually incoherent optical beams that propagate collinearly in open-circuit photovoltaic photorefractive media is investigated. It is shown that an incoherently coupled bright-dark spatial soliton pair can be formed due to photovoltaic effect. The physical properties of such a soliton pair are also discussed.

  17. Star Formation Rates in Low Surface Brightness Galaxies

    NARCIS (Netherlands)

    Pickering, T. E.; Impey, C. D.; van Gorkom, J.; Bothun, G. D.

    1994-01-01

    The low surface brightness (LSB) disk galaxies found in recent surveys (e.g.,\\ Schombert et al. 1992, AJ, 103, 1107) tend to be blue and gas rich. These properties along with their low mean surface luminosity and H i densities imply an inefficient mode of star formation. The Hα images that we presen

  18. Soil Moisture Active/Passive (SMAP) Forward Brightness Temperature Simulator

    Science.gov (United States)

    Peng, Jinzheng; Peipmeier, Jeffrey; Kim, Edward

    2012-01-01

    The SMAP is one of four first-tier missions recommended by the US National Research Council's Committee on Earth Science and Applications from Space (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007) [1]. It is to measure the global soil moisture and freeze/thaw from space. One of the spaceborne instruments is an L-band radiometer with a shared single feedhorn and parabolic mesh reflector. While the radiometer measures the emission over a footprint of interest, unwanted emissions are also received by the antenna through the antenna sidelobes from the cosmic background and other error sources such as the Sun, the Moon and the galaxy. Their effects need to be considered accurately, and the analysis of the overall performance of the radiometer requires end-to-end performance simulation from Earth emission to antenna brightness temperature, such as the global simulation of L-band brightness temperature simulation over land and sea [2]. To assist with the SMAP radiometer level 1B algorithm development, the SMAP forward brightness temperature simulator is developed by adapting the Aquarius simulator [2] with necessary modifications. This poster presents the current status of the SMAP forward brightness simulator s development including incorporating the land microwave emission model and its input datasets, and a simplified atmospheric radiative transfer model. The latest simulation results are also presented to demonstrate the ability of supporting the SMAP L1B algorithm development.

  19. Quadrature measurements of a bright squeezed state via sideband swapping

    DEFF Research Database (Denmark)

    Schneider, J.; Glockl, O.; Leuchs, G.;

    2009-01-01

    The measurement of an arbitrary quadrature of a bright quantum state of light is a commonly requested action in many quantum information protocols, but it is experimentally challenging with previously proposed schemes. We suggest that the quadrature be measured at a specific sideband frequency of...

  20. Matter wave interference pattern in the collision of bright solitons

    International Nuclear Information System (INIS)

    We investigate the dynamics of Bose-Einstein condensates in a quasi one-dimensional regime in a time-dependent trap and show analytically that it is possible to observe matter wave interference patterns in the intra-trap collision of two bright solitons by selectively tuning the trap frequency and scattering length.

  1. Minimum-phase distribution of cosmic source brightness

    International Nuclear Information System (INIS)

    Minimum-phase distributions of brightness (profiles) for cosmic radio sources 3C 144 (the wave lambda=21 cm), 3C 338 (lambda=3.5 m), and 3C 353 (labda=31.3 cm and 3.5 m) are obtained. A real possibility for the profile recovery from module fragments of its Fourier-image is shown

  2. The HI dominated Low Surface Brightness Galaxy KKR17

    CERN Document Server

    Lam, Man I; Yang, Ming; Zhou, Zhi-Min; Du, Wei; Zhu, Yi-Nan

    2014-01-01

    We present new narrow-band (H$\\alpha$ and [OIII]) imagings and optical spectrophotometry of HII regions for a gas-rich low surface brightness irregular galaxy, KKR 17. The central surface brightness of the galaxy is $\\mu_0(B)$ = 24.15 $\\pm$0.03 mag~sec$^{-2}$. The galaxy was detected by \\emph{Arecibo Legacy Fast ALFA survey} (ALFALFA), and its mass is dominated by neutral hydrogen (HI) gas. In contrast, both the stellar masses of the bright HII and diffuse stellar regions are small. In addition, the fit to the spectral energy distribution to each region shows the stellar populations of HII and diffuse regions are different. The bright HII region contains a large fraction of O-type stars, revealing the recent strong star formation, whereas the diffuse region is dominated by median age stars, which has a typical age of $\\sim$ 600 Myrs. Using the McGaugh's abundance model, we found that the average metallicity of KKR 17 is 12 + (O/H) = 8.0 $\\pm$ 0.1. The star formation rate of KKR 17 is 0.21$\\pm$0.04 M$_{\\odot}$...

  3. The "Brightness Rules" Alternative Conception for Light Bulb Circuits

    Science.gov (United States)

    Bryan, Joel A.; Stuessy, Carol

    2006-01-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

  4. Exploring the Multi-Wavelength, Low Surface Brightness Universe

    Science.gov (United States)

    Brunner, R. J.; Djorgovski, S. G.; Gal, R. R.; Odewahn, S. C.

    1999-12-01

    Our current understanding of the low surface brightness universe is quite incomplete, not only in the optical, but also in other wavelength regimes. We have, therefore, begun an exploration of the multi-wavelength, low surface brightness universe. This project currently involves data from DPOSS (Digitized Palomar Optical Sky Survey), 2MASS (Two Micron All Sky Survey), IRAS (Infrared Astronomical Satellite), and several neutral hydrogen surveys. We present some initial results of this work as well as discuss the implications of this work on future virtual observatories. Our main scientific goals have been the search for low surface brightness galaxies, including local group dwarf spheroidals, and also optical counterparts to high velocity clouds. Our techniques are complimentary to normal data reduction pipeline techniques in that we focus on the diffuse emission that is ignored or removed by more traditional algorithms. This requires, of course, a spatial filtering which must account for objects of interest, in addition to observational artifacts (e.g.,\\ bright stellar halos). Finally, with this work, we are exploring the intersection of the catalog and image domains in order to maximize the scientific information we can extract from the federation of large survey data.

  5. The star-bright hour : [poems] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2003-01-01

    Autori lühitutvustus lk. 231. Sisu: The star-bright hour ; The debt ; Not a dream ; Fog-bound ; Corals in an Ancient river ; Frou-frou 1-3. Orig.: Tähetund ; Vilepuhuja ; Võlg ; "Mitte viirastus, meelepett..." ; Udus ; Korallid Emajões ; Froufrou 1-3

  6. The star-bright hour : [luuletused] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2006-01-01

    Sisu: The star-bright hour ; Not a dream ; The Piper ; Corals in an ancent river. Luuletused pärinevad kogumikust "Tuulelaeval valgusest on aerud = Windship with Oars of Light. (Tallinn : Huma, 2001). Orig.: Tähetund ; Mitte viirastus, meelepett ; Vilepuhuja ; Korallid Emajões

  7. Enhancing the brightness of high current electron guns

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, W.A.; Birx, D.; Boyd, J.K.; Caporaso, G.; Weir, J.T.

    1985-01-01

    Concepts such as the two-beam accelerator offer the possibility of translating pulsed power technology into a form useful to the design of high luminosity accelerators for high-energy physics applications. Realization of the promise of these concepts will require the design of electron guns which are optimized with respect to beam brightness at current levels of approximately 1 kA. Because high luminosity implies accelerator operation at high repetition rates, the high-current beam source must be designed so that the beam does not intercept the electrodes. In our investigations of electron gun configurations, we have found that the brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. To investigate the sensitivity of beam brightness to these factors in a manner suitable for modelling transient phenomena at the beam head, we have developed a Darwin approximation particle code, DPC. The main component in our experimental program is a readily modified electron gun that allows us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MW/cm. We have also developed several diagnostics suitable for measuring the brightness of intense, low-emittance beams.

  8. Bright X-ray galaxies in SDSS filaments

    OpenAIRE

    Tugay, A. V.

    2013-01-01

    Eighteen bright X-ray emitting galaxies were found in nearby filaments within SDSS region. Basic X-ray spectral parameters were estimated for these galaxies using power law model with photoelectric absorption. A close pair of X-ray galaxies was found.

  9. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  10. General Relativity and Compact Objects

    CERN Document Server

    Gupta, Patrick Das

    2015-01-01

    Starting with the conceptual foundation of general relativity (GR) - equivalence principle, space-time geometry and special relativity, I train cross hairs on two characteristic predictions of GR - black holes and gravitational waves. These two consequences of GR have played a significant role in relativistic astrophysics, e.g. compact X-ray sources, quasars, blazars, coalescing binary pulsars, etc. With quantum theory wedded to GR, particle production from vacuum becomes a generic feature whenever event horizons are present. In this paper, I shall briefly discuss the fate of a `black hole atom' when Hawking radiation is taken into account. In the context of gravitational waves, I shall focus on the possible consequences of gravitational and electromagnetic radiation from highly magnetized and rapidly spinning white dwarfs. The discovery of RX J0648.0-4418 system - a WD in a binary with mass slightly over 1.2 $ M_{\\odot}$, and rotating with spin period as short as 13.2 s, provides an impetus to revisit the pr...

  11. Ultra Compact Imaging Spectrometer (UCIS)

    Science.gov (United States)

    Blaney, Diana L.; Green, Robert; Mouroulis, Pantazis; Cable, Morgan; Ehlmann, Bethany; Haag, Justin; Lamborn, Andrew; McKinley, Ian; Rodriguez, Jose; van Gorp, Byron

    2016-10-01

    The Ultra Compact Imaging Spectrometer (UCIS) is a modular visible to short wavelength infrared imaging spectrometer architecture which could be adapted to a variety of mission concepts requiring low mass and low power. Imaging spectroscopy is an established technique to address complex questions of geologic evolution by mapping diagnostic absorption features due to minerals, organics, and volatiles throughout our solar system. At the core of UCIS is an Offner imaging spectrometer using M3 heritage and a miniature pulse tube cryo-cooler developed under the NASA Maturation of Instruments for Solar System Exploration (MatISSE) program to cool the focal plane array. The TRL 6 integrated spectrometer and cryo-cooler provide a basic imaging spectrometer capability that is used with a variety of fore optics to address lunar, mars, and small body science goals. Potential configurations include: remote sensing from small orbiters and flyby spacecraft; in situ panoramic imaging spectroscopy; and in situ micro-spectroscopy. A micro-spectroscopy front end is being developed using MatISSE funding with integration and testing planned this summer.

  12. Compact Nanowire Sensors Probe Microdroplets.

    Science.gov (United States)

    Schütt, Julian; Ibarlucea, Bergoi; Illing, Rico; Zörgiebel, Felix; Pregl, Sebastian; Nozaki, Daijiro; Weber, Walter M; Mikolajick, Thomas; Baraban, Larysa; Cuniberti, Gianaurelio

    2016-08-10

    The conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward sensitive, optics-less analysis of biochemical processes with high throughput, where a single device can be employed for probing of thousands of independent reactors. Here we combine droplet microfluidics with the compact silicon nanowire based field effect transistor (SiNW FET) for in-flow electrical detection of aqueous droplets one by one. We chemically probe the content of numerous (∼10(4)) droplets as independent events and resolve the pH values and ionic strengths of the encapsulated solution, resulting in a change of the source-drain current ISD through the nanowires. Further, we discuss the specificities of emulsion sensing using ion sensitive FETs and study the effect of droplet sizes with respect to the sensor area, as well as its role on the ability to sense the interior of the aqueous reservoir. Finally, we demonstrate the capability of the novel droplets based nanowire platform for bioassay applications and carry out a glucose oxidase (GOx) enzymatic test for glucose detection, providing also the reference readout with an integrated parallel optical detector. PMID:27417510

  13. Compact Nanowire Sensors Probe Microdroplets.

    Science.gov (United States)

    Schütt, Julian; Ibarlucea, Bergoi; Illing, Rico; Zörgiebel, Felix; Pregl, Sebastian; Nozaki, Daijiro; Weber, Walter M; Mikolajick, Thomas; Baraban, Larysa; Cuniberti, Gianaurelio

    2016-08-10

    The conjunction of miniature nanosensors and droplet-based microfluidic systems conceptually opens a new route toward sensitive, optics-less analysis of biochemical processes with high throughput, where a single device can be employed for probing of thousands of independent reactors. Here we combine droplet microfluidics with the compact silicon nanowire based field effect transistor (SiNW FET) for in-flow electrical detection of aqueous droplets one by one. We chemically probe the content of numerous (∼10(4)) droplets as independent events and resolve the pH values and ionic strengths of the encapsulated solution, resulting in a change of the source-drain current ISD through the nanowires. Further, we discuss the specificities of emulsion sensing using ion sensitive FETs and study the effect of droplet sizes with respect to the sensor area, as well as its role on the ability to sense the interior of the aqueous reservoir. Finally, we demonstrate the capability of the novel droplets based nanowire platform for bioassay applications and carry out a glucose oxidase (GOx) enzymatic test for glucose detection, providing also the reference readout with an integrated parallel optical detector.

  14. Soil compaction and fertilization in soybean productivity

    Directory of Open Access Journals (Sweden)

    Beutler Amauri Nelson

    2004-01-01

    Full Text Available Soil compaction and fertilization affect soybean development. This study evaluated the effects of soil compaction and fertilization on soybean (Glycine max cv. Embrapa 48 productivity in a Typic Haplustox under field conditions in Jaboticabal, SP, Brazil. A completely randomized design with a 5 x 2 factorial layout (compaction vs. fertilization, with four replications in each treatment, was employed. Each experimental unit (replicate consisted of a 3.6 m² useful area. After the soil was prepared by cultivation, an 11 Mg tractor passed over it a variable number of times to create five levels of compaction. Treatments were: T0= no compaction, T1= one tractor pass, T2= two, T4= four, and T6= six passes, and no fertilizer and fertilizer to give soybean yields of 2.5 to 2.9 Mg ha-1. Soil was sampled at depths of 0.02-0.05, 0.07-0.10, and 0.15-0.18 m to determine macro and microporosity, penetration resistance (PR, and bulk density (Db. After 120 days growing under these conditions, the plants were analyzed in terms of development (plant height, number of pods, shoot dry matter per plant and weight of 100 seeds and seed productivity per hectare. Soil compaction decreased soybean development and productivity, but this effect was decreased by soil fertilization, showing that such fertilization increased soybean tolerance to soil compaction.

  15. Explosive compaction of CuCr alloys

    Institute of Scientific and Technical Information of China (English)

    李金平; 罗守靖; 龚朝晖; 牛玮; 纪松

    2002-01-01

    The production of CuCr alloys utilizing explosive compaction was studied. Mixture powders of CuCr alloys placed in tubes with a dimension of d14.0mm×21.4mm can be compacted using explosive pads of 16.5mm or 22.5mm. Thicker pads of explosive make the compacts more porous. The effects of the ratio of me/mp, ratio of me/(mp+mt) and impact energy on the density of compacts were similar, they were chosen to control explosive compaction, respectively. When adequate value of the parameters me/mp, me/(mt+mp) and impact energy of unit area of tube was chosen, high density(7.858g/cm3), high hardness(HB189) and low conductance (13.6MS/m) of CuCr alloys could be made by explosive compaction. The general properties of CuCr alloys by explosive compaction are similar to those of CuCr alloys by traditional process.

  16. A new strategy for synthesizing AgInS2 quantum dots emitting brightly in near-infrared window for in vivo imaging

    DEFF Research Database (Denmark)

    Tan, Lianjiang; Liu, Shuiping; Li, Xiaoqiang;

    2015-01-01

    A new strategy for fabricating water-dispersible AgInS2 quantum dots (QDs) with bright near-infrared (NIR) emission is demonstrated. A type of multidentate polymer (MDP) was synthesized and utilized as a compact capping ligand for the AgInS2 QDs. Using silver nitrate, indium acetate and sulfur......-hydrazine hydrate complex as the precursors, MDP-capping AgInS2 QDs were synthesized in aqueous solution at room temperature. Characterization indicates that the MDP-capping AgInS2 QDs are highly photoluminescent in NIR window and possess good photostability. Also, the QDs are stable in different media and have low...

  17. Self Compacting Concrete And Its Properties

    Directory of Open Access Journals (Sweden)

    S. Mahesh

    2014-08-01

    Full Text Available Self-compacting concrete (SCC, which flows under its own weight and doesn’t require any external vibration for compaction, has revolutionized concrete placement. Such concrete should have relatively low yield value to ensure high flow ability, a moderate viscosity to resists segregation and bleeding and must maintain its homogeneity during transportation, placing and curing to ensure adequate structural performance and long term durability. Self-compacting concrete (SCC can be defined as a fresh concrete which possesses superior flow ability under maintained stability (i.e. no segregation thus allowing self-compaction that is, material consolidation without addition of energy. Self-compacting concrete is a fluid mixture suitable for placing in structures with Congested reinforcement without vibration and it helps in achieving higher quality of surface finishes. However utilization of high reactive Metakaolin and Flyash asan admixtures as an effective pozzolan which causes great improvement in the porestructure. The relative proportions of key components are considered by volumerather than by mass. self compacting concrete (SCC mix design with 29% of coarse aggregate, replacement of cement with Metakaolin and class F flyash, combinations of both and controlled SCC mix with 0.36 water/cementitious ratio(by weight and388 litre/m3 of cement paste volume. Crushed granite stones of size 16mm and12.5mm are used with a blending 60:40 by percentage weight of total coarse aggregate. Self-compacting concrete compactibility is affected by the characteristics of materials and the mix proportions; it becomes necessary to evolve a procedure formix design of SCC. The properties of different constituent materials used in this investigation and its standard tests procedures for acceptance characteristics of self compacting concrete such as slump flow, V-funnel and L-Box are presented.

  18. Compaction of North-sea chalk

    Science.gov (United States)

    Keszthelyi, Dániel; Dysthe, Dag Kristian; Jamtveit, Bjørn

    2014-05-01

    The Ekofisk field is the largest petroleum field in the Norwegian North Sea territory where oil is produced from chalk formations. Early stage of oil production caused considerable changes in pore fluid pressure which led to a reservoir compaction. Pore collapse mechanism caused by the dramatic increase of effective stress, which in turn was caused by the pressure reduction by hydrocarbon depletion, was early identified as a principal reason for the reservoir compaction (Sulak et al. 1991). There have been several attempts to model this compaction. They performed with variable success on predicting the Ekofisk subsidence. However, the most of these models are based on empirical relations and do not investigate in detail the phenomena involved in the compaction. In sake of predicting the Ekofisk subsidence while using only independently measurable variables we used a chalk compaction model valid on geological time-scales (Japsen et al. 2011) assuming plastic pore-collapse mechanism at a threshold effective stress level. We identified the phenomena involved in the pore collapse. By putting them in a sequential order we created a simple statistical analytical model. We also investigated the time-dependence of the phenomena involved and by assuming that one of the phenomena is rate-limiting we could make estimations of the compaction rate at smaller length-scales. By carefully investigating the nature of pressure propagation we could upscale our model to reservoir scale. We found that the predicted compaction rates are close enough to the measured rates. We believe that we could further increase accuracy by refining our model. Sulak, R. M., Thomas, L. K., Boade R. R. (1991) 3D reservoir simulation of Ekofisk compaction drive. Journal of Petroleum Technology, 43(10):1272-1278, 1991. Japsen, P., Dysthe, D. K., Hartz, E. H., Stipp, S. L. S., Yarushina, V. M., Jamtveit. (2011) A compaction front in North Sea chalk. Journal of Geophysical Research: Solid Earth (1978

  19. Subsoil Compaction as a Climate Damage Indicator

    Directory of Open Access Journals (Sweden)

    Márta Birkás

    2009-06-01

    Soil compaction has become a soil management problem during the last decade as a result of the occurrence of periods of water-logging as well as droughts. This study contains an evaluation of factors relating to subsoil compaction, as indicator of climate effects on arable fields. This paper is based on soil condition monitoring and measuring that was started 32 years ago and on short and long-term experiments modeling and checking the extension of compaction in the soil. The survey comprised 1526 monitoring places and 38 experimental plots. The following five points were chosen for monitoring: 1 root zone state (to a depth of 0-60 cm; 2 occurrence of compacted layer (indicating likelihood of risk; 3 extension of the compacted layer (indicating the degree of damage; 4 long term effects of tillage (soil state deterioration or improvement, and 5 tillage-induced water-logging and drought damage impacts on yield loss. The main objectives of the experiments were: 1 occurrence and the extent of tillage-pan damage in soils of different susceptibility to compaction; 2 consequences on water management in each of the years covered by the experiments; 3 soil quality consequences, and 4 alleviation of pan-compaction by mechanical and biological methods. Long-term field monitoring and experimental work have both convincingly proven a correlation between subsoil compaction and the degree of climatic damage. In view of the findings, trends in soil tillage can be grouped into the following two categories: climate damage mitigating and climate-stress increasing ones. The formation and location of compacted layers provided information concerning the depth, the method and the type of tillage applied, along with the expected risk for crop production under extreme climate conditions.

  20. High-efficiency high-brightness diode lasers at 1470 nm/1550 nm for medical and defense applications

    Science.gov (United States)

    Gallup, Kendra; Ungar, Jeff; Vaissie, Laurent; Lammert, Rob; Hu, Wentao

    2012-03-01

    Diode lasers in the 1400 nm to 1600 nm regime are used in a variety of applications including pumping Er:YAG lasers, range finding, materials processing, aesthetic medical treatments and surgery. In addition to the compact size, efficiency, and low cost advantages of traditional diode lasers, high power semiconductor lasers in the eye-safe regime are becoming widely used in an effort to minimize the unintended impact of potentially hazardous scattered optical radiation from the laser source, the optical delivery system, or the target itself. In this article we describe the performance of high efficiency high brightness InP laser bars at 1470nm and 1550nm developed at QPC Lasers for applications ranging from surgery to rangefinding.

  1. Deep multiband surface photometry on star forming galaxies: I. A sample of 24 blue compact galaxies

    CERN Document Server

    Micheva, Genoveva; Bergvall, Nils; Zackrisson, Erik; Masegosa, Josefa; Marquez, Isabel; Marquart, Thomas; Durret, Florence

    2012-01-01

    [Abridged] We present deep optical and near-infrared UBVRIHKs imaging data for 24 blue compact galaxies (BCGs). The sample contains luminous dwarf and intermediate-mass BCGs which are predominantly metal-poor, although a few have near-solar metallicities. We have analyzed isophotal and elliptical integration surface brightness and color profiles, extremely deep (mu_B<29 mag arcsec^{-2}) contour maps and RGB images for each galaxy in the sample. The colors are compared to different spectral evolutionary models. We detect extremely extended low surface brightness (LSB) components dominant beyond the Holmberg radius as well as optical bridges between companion galaxies at the mu_V~28th mag arcsec^{-2} isophotal level. The central surface brightness mu_0 and scale length h_r are derived from two radial ranges typically assumed to be dominated by the underlying host galaxy. We find that mu_0 and h_r of the BCGs host deviate from those of dwarf ellipticals (dE) and dwarf irregulars (dI) solely due to a strong bu...

  2. Radio and Mid-Infrared Properties of Compact Starbursts: Distancing Themselves from the Main Sequence

    CERN Document Server

    Murphy, E J; Armus, L; Condon, J J; Evans, A S

    2013-01-01

    We investigate the relationship between 8.44\\,GHz brightness temperatures and 1.4 to 8.44\\,GHz radio spectral indices with 6.2\\,$\\mu$m polycyclic aromatic hydrocarbon (PAH) emission and 9.7\\,$\\mu$m silicate absorption features for a sample of 36 local luminous and ultra-luminous infrared galaxies. We find that galaxies having small 6.2\\,$\\mu$m PAH equivalent widths (EQWs), which signal the presence of weak PAH emission and/or an excess of very hot dust, also have flat spectral indices. The three active galactic nuclei (AGN) identified through their excessively large 8.44\\,GHz brightness temperatures are also identified as AGN via their small 6.2\\,$\\mu$m PAH EQWs. We also find that the flattening of the radio spectrum increases with increasing silicate optical depth, 8.44\\,GHz brightness temperature, and decreasing size of the radio source even after removing potential AGN, supporting the idea that compact starbursts show spectral flattening as the result of increased free-free absorption. These correlations a...

  3. Galaxy interactions in the Hickson Compact Group 88

    CERN Document Server

    Brosch, Noah

    2015-01-01

    I present observations of the Hickson Compact Group 88 (HCG88) obtained during the commissioning of a new 28-inch telescope at the Wise Observatory. This galaxy group was advertised to be non-interacting, or to be in a very early interaction stage, but this is not the case. The observations reported here were done using a "luminance" filter, essentially a very broad R filter, reaching a low surface brightness level of about 26 mag per square arcsec. Additional observations were obtained in a narrow spectral band approximately centered on the rest-frame H-alpha line from the group. Contrary to previous studies, my observations show that at least two of the major galaxies have had significant interactions in the past, although probably not between themselves. I report the discovery of a faint extended tail emerging from the brightest of the group galaxies, severe isophote twisting and possible outer shells around another galaxy, and map the HII regions in all the galaxies.

  4. The Evolution of Luminous Compact Blue Galaxies: Disks or Spheroids?

    CERN Document Server

    Pisano, D J; Garland, C A; Guzman, R; Castander, F J; Perez-Gallego, J

    2011-01-01

    Luminous compact blue galaxies (LCBGs) are a diverse class of galaxies characterized by high luminosity, blue color, and high surface brightness that sit at the critical juncture of galaxies evolving from the blue to the red sequence. As part of our multi-wavelength survey of local LCBGs, we have been studying the HI content of these galaxies using both single-dish telescopes and interferometers. Our goals are to determine if single-dish HI observations represent a true measure of the dynamical mass of LCBGs and to look for signatures of recent interactions that may be triggering star formation in LCBGs. Our data show that while some LCBGs are undergoing interactions, many appear isolated. While all LCBGs contain HI and show signatures of rotation, the population does not lie on the Tully-Fisher relation nor can it evolve onto it. Furthermore, the HI maps of many LCBGs show signatures of dynamically hot components, suggesting that we are seeing the formation of a thick disk or spheroid in at least some LCBGs....

  5. The Evolution of Luminous Compact Blue Galaxies: Disks or Spheroids?

    CERN Document Server

    Pisano, D J; Rabidoux, K; Wolfe, S; Guzman, R; Perez-Gallego, J; Castander, F J

    2009-01-01

    Luminous compact blue galaxies (LCBGs) are a diverse class of galaxies characterized by high luminosities, blue colors, and high surface brightnesses. Residing at the high luminosity, high mass end of the blue sequence, LCBGs sit at the critical juncture of galaxies that are evolving from the blue to the red sequence. Yet we do not understand what drives the evolution of LCBGs, nor how they will evolve. Based on single-dish HI observations, we know that they have a diverse range of properties. LCBGs are HI-rich with M(HI)=10^{9-10.5} M(sun), have moderate M(dyn)=10^{10-12} M(sun), and 80% have gas depletion timescales less than 3 Gyr. These properties are consistent with LCBGs evolving into low-mass spirals or high mass dwarf ellipticals or dwarf irregulars. However, LCBGs do not follow the Tully-Fisher relation, nor can most evolve onto it, implying that many LCBGs are not smoothly rotating, virialized systems. GMRT and VLA HI maps confirm this conclusion revealing signatures of recent interactions and dynam...

  6. The Neutral ISM in Nearby Luminous Compact Blue Galaxies

    CERN Document Server

    Garland, C A; Williams, J P; Guzmán, R; Castander, F J

    2003-01-01

    We observed 20 nearby Luminous Compact Blue Galaxies (LCBGs) in HI and CO(J=2-1) with the GBT and JCMT. These ~L^star galaxies are blue, high surface brightness, starbursting, high metallicity galaxies with an underlying older stellar population. They are common at z~1, but rare in the local Universe. It has been proposed that intermediate redshift LCBGs may be the progenitors of local dwarf ellipticals or low luminosity spirals, or that they may be more massive disks forming from the center outward to become L^star galaxies. To discriminate among various possible evolutionary scenarios, we have measured the dynamical masses and gas depletion time scales of this sample of nearby LCBGs. We find that local LCBGs span a wide range of dynamical masses, from 4 x 10^9 to 1 x 10^11 M_solar (measured within R_25). Molecular gas in local LCBGs is depleted quite quickly, in 30 to 200 million years. The molecular plus atomic gas is depleted in 30 million to 10 billion years; however, ~80% of the local LCBGs deplete thei...

  7. Search for Blue Compact Dwarf Galaxies During Quiescence

    CERN Document Server

    Almeida, J Sanchez; Amorin, R; Aguerri, J A; Sanchez-Janssen, R; Tenorio-Tagle, G

    2008-01-01

    Blue Compact Dwarf (BCD) galaxies are metal poor systems going through a major starburst that cannot last for long. We have identified galaxies which may be BCDs during quiescence (QBCD), i.e., before the characteristic starburst sets in or when it has faded away. These QBCD galaxies are assumed to be like the BCD host galaxies. The SDSS/DR6 database provides ~21500 QBCD candidates. We also select from SDSS/DR6 a complete sample of BCD galaxies to serve as reference. The properties of these two galaxy sets have been computed and compared. The QBCD candidates are thirty times more abundant than the BCDs, with their luminosity functions being very similar except for the scaling factor, and the expected luminosity dimming associated with the end of the starburst. QBCDs are redder than BCDs, and they have larger HII region based oxygen abundance. QBCDs also have lower surface brightness. The BCD candidates turn out to be the QBCD candidates with the largest specific star formation rate (actually, with the largest...

  8. Compact groups from the Millennium Simulations: I. Nature and properties

    CERN Document Server

    Diaz-Gimenez, Eugenia; Muriel, Hernan; Mamon, Gary

    2008-01-01

    We identify compact groups of galaxies (CGs) within mock galaxy catalogs from the Millennium Simulation at z=0 with the semi-analytic models of galaxy formation by Croton et al. (C06), Bower et al. (B06) and De Lucia & Blaizot (DLB). CGs are identified using the same 2D criteria as those visually applied by Hickson (1982) to his CGs (HCGs). Half of the CGs identified in projection contain at least 4 accordant velocities (mvCGs). In comparison to mvCGs, the HCGs are only 2% complete, missing CGs either faint, low surface brightness (SB), apparently small, or with a strongly dominant galaxy. We define physically dense mvCGs as those whose maximum real space galaxy separation of their smallest clump of 4 galaxies is below a threshold chosen such that the 3D shapes of these clumps are similar to those of groups selected in real space. Then, 25% of the mvCGs are dense (50% of mvCGs contain a dense triplet), as are 25-50% of the mvCGs resampled according to the HCG completeness functions. The majority of mvCGs ...

  9. Kilonova/Macronova Emission from Compact Binary Mergers

    CERN Document Server

    Tanaka, Masaomi

    2016-01-01

    We review current understanding of kilonova/macronova emission from compact binary mergers (mergers of two neutron stars or a neutron star and a black hole). Kilonova/macronova is optical and near-infrared emission powered by radioactive decays of r-process nuclei. Emission from the dynamical ejecta with ~0.01 Msun is likely to have a luminosity of ~10^{40}-10^{41} erg s^{-1} with a characteristic timescale of about 1 week. The spectral peak is located in red optical or near-infrared wavelengths. A subsequent accretion disk wind may provide an additional luminosity, or an earlier/bluer emission if it is not absorbed by the precedent dynamical ejecta. The detection of near-infrared excess in the afterglow of short GRB 130603B and possible optical excess in GRB 060614 supports the concept of the kilonova/macronova scenario. At 200 Mpc distance, a typical brightness of kilonova/macronova with 0.01 Msun ejecta is expected to be about 22 mag and the emission rapidly fades to >24 mag within ~10 days after the merge...

  10. High Velocity Compact Clouds in the Sagittarius C Region

    CERN Document Server

    Tanaka, Kunihiko; Matsumura, Shinji; Nagai, Makoto; Kamegai, Kazuhisa

    2014-01-01

    We report the detection of extremely broad emission toward two molecular clumps in the Galactic central molecular zone. We have mapped the Sagittarius C complex ($-0^\\circ.61 < l < -0^\\circ.27$, $-0^\\circ.29 < b < 0^\\circ.04$) in the HCN $J$ = 4--3, $\\mathrm{^{13}CO}$ $J$ = 3--2, and $\\mathrm{H^{13}CN}$ $J$ = 1--0 lines with the ASTE 10 m and NRO 45 m telescopes, detecting bright emission with $80\\mbox{--}120$\\ $\\mathrm{km\\,s^{-1}}$ velocity width (in full-width at zero intensity) toward CO$-0.30$$-0.07$ and CO$-0.40$$-0.22$, which are high velocity compact clouds (HVCCs) identified with our previous CO $J$ = 3--2 survey. Our data reveal an interesting internal structure of CO$-0.30$$-0.07$ comprising a pair of high velocity lobes. The spatial-velocity structure of CO$-0.40$$-0.22$ can be also understood as multiple velocity component, or a velocity gradient across the cloud. They are both located on the rims of two molecular shells of about 10 pc in radius. Kinetic energies of CO$-0.30$$-0.07$ an...

  11. Compact X-ray source based on Compton backscattering

    CERN Document Server

    Bulyak, E V; Zelinsky, A; Karnaukhov, I; Kononenko, S; Lapshin, V G; Mytsykov, A; Telegin, Yu P; Khodyachikh, A; Shcherbakov, A; Molodkin, V; Nemoshkalenko, V; Shpak, A

    2002-01-01

    The feasibility study of an intense X-ray source based on the interaction between the electron beam in a compact storage ring and the laser pulse accumulated in an optical resonator is carried out. We propose to reconstruct the 160 MeV electron storage ring N-100, which was shutdown several years ago. A new magnetic lattice will provide a transverse of electron beam size of approx 35 mu m at the point of electron beam-laser beam interaction. The proposed facility is to generate X-ray beams of intensity approx 2.6x10 sup 1 sup 4 s sup - sup 1 and spectral brightness approx 10 sup 1 sup 2 phot/0.1%bw/s/mm sup 2 /mrad sup 2 in the energy range from 10 keV up to 0.5 MeV. These X-ray beam parameters meet the requirements for most of technological and scientific applications. Besides, we plan to use the new facility for studying the laser cooling effect.

  12. Compacting Plastic-Bonded Explosive Molding Powders to Dense Solids

    Energy Technology Data Exchange (ETDEWEB)

    B. Olinger

    2005-04-15

    Dense solid high explosives are made by compacting plastic-bonded explosive molding powders with high pressures and temperatures for extended periods of time. The density is influenced by manufacturing processes of the powders, compaction temperature, the magnitude of compaction pressure, pressure duration, and number of repeated applications of pressure. The internal density variation of compacted explosives depends on method of compaction and the material being compacted.

  13. Strategy Guideline. Compact Air Distribution Systems

    Energy Technology Data Exchange (ETDEWEB)

    Burdick, Arlan [IBACOS, Inc., Pittsburgh, PA (United States)

    2013-06-01

    This guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

  14. The formation of compact groups of galaxies

    Institute of Scientific and Technical Information of China (English)

    马駬; 俞允强

    1999-01-01

    In the compact group of galaxies the galaxies can merge into a few massive ones in a very short time, so they must be formed very recently. On the other hand, according to the theory of structure formation, the denser system should form earlier. By analyzing the apparent paradox, we suggest that the merging process of CDM halo plays an important role in the formation of the compact groups of galaxies: it delays the formation of compact groups of galaxies, and makes the groups of galaxies much denser.

  15. Relativistic Solutions of Anisotropic Compact Objects

    CERN Document Server

    Paul, Bikash Chandra

    2016-01-01

    We present a class of new relativistic solutions with anisotropic fluid for compact stars in hydrostatic equilibrium. The interior space-time geometry considered here for compact objects are described by parameters namely, $\\lambda$, $k$, $A$, $R$ and $n$. The values of the geometrical parameters are determined here for obtaining a class of physically viable stellar models. The energy-density, radial pressure and tangential pressure are finite and positive inside the anisotropic stars. Considering some stars of known mass we present stellar models which describe compact astrophysical objects with nuclear density.

  16. Generalized model for anisotropic compact stars

    CERN Document Server

    Maurya, S K; Ray, Saibal; Deb, Debabrata

    2016-01-01

    In the present investigation an exact generalized model for anisotropic compact stars of embedding class one is sought for under general relativistic background. The generic solutions are verified by exploring different physical aspects, viz. energy conditions, mass-radius relation, stability of the models, in connection to their validity. It is observed that the model present here for compact stars is compatible with all these physical tests and thus physically acceptable as far as the compact star candidates $RXJ~1856-37$, $SAX~J~1808.4-3658~(SS1)$ and $SAX~J~1808.4-3658~(SS2)$ are concerned.

  17. Subsoil Compaction as a Climate Damage Indicator

    Directory of Open Access Journals (Sweden)

    Márta Birkás

    2009-06-01

    Full Text Available Some forms of soil compaction occur on arable lands both in Hungary (1.82 million ha and in Croatia (0.97 million ha having negative impacts on agricultural production. Tillage-induced subsoil compaction has oft en occurred in the Pannonian region in relation to traffic-induced compaction.Soil compaction has become a soil management problem during the last decade as a result of the occurrence of periods of water-logging as well as droughts. This study contains an evaluation of factors relating to subsoil compaction, as indicator of climate effects on arable fields. This paper is based on soil condition monitoring and measuring that was started 32 years ago and on short and long-term experiments modeling and checking the extension of compaction in the soil. The survey comprised 1526 monitoring places and 38 experimental plots. The following five points were chosen for monitoring: 1 root zone state (to a depth of 0-60 cm; 2 occurrence of compacted layer (indicating likelihood of risk; 3 extension of the compacted layer (indicating the degree of damage; 4 long term effects of tillage (soil state deterioration or improvement, and 5 tillage-induced water-logging and drought damage impacts on yield loss. The main objectives of the experiments were: 1 occurrence and the extent of tillage-pan damage in soils of different susceptibility to compaction; 2 consequences on water management in each of the years covered by the experiments; 3 soil quality consequences, and 4 alleviation of pan-compaction by mechanical and biological methods. Long-term field monitoring and experimental work have both convincingly proven a correlation between subsoil compaction and the degree of climatic damage. In view of the findings, trends in soil tillage can be grouped into the following two categories: climate damage mitigating and climate-stress increasing ones. The formation and location of compacted layers provided information concerning the depth, the method and the

  18. L^2-homology for compact quantum groups

    OpenAIRE

    Kyed, David

    2006-01-01

    A notion of L^2-homology for compact quantum groups is introduced, generalizing the classical notion for countable, discrete groups. If the compact quantum group in question has tracial Haar state, it is possible to define its L^2-Betti numbers and Novikov-Shubin invariants/capacities. It is proved that these L^2-Betti numbers vanish for the Gelfand dual of a compact Lie group and that the zeroth Novikov-Shubin invariant equals the dimension of the underlying Lie group. Finally, we relate our...

  19. Compact vs. Exponential-Size LP Relaxations

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.D.; Lancia, G.

    2000-09-01

    In this paper we introduce by means of examples a new technique for formulating compact (i.e. polynomial-size) LP relaxations in place of exponential-size models requiring separation algorithms. In the same vein as a celebrated theorem by Groetschel, Lovasz and Schrijver, we state the equivalence of compact separation and compact optimization. Among the examples used to illustrate our technique, we introduce a new formulation for the Traveling Salesman Problem, whose relaxation we show equivalent to the subtour elimination relaxation.

  20. High brightness sub-nanosecond Q-switched laser using volume Bragg gratings

    Science.gov (United States)

    Anderson, Brian M.; Hale, Evan; Venus, George; Ott, Daniel; Divliansky, Ivan; Glebov, Leonid

    2016-03-01

    The design of Q-switched lasers capable of producing pulse widths of 100's of picoseconds necessitates the cavity length be shorter than a few centimeters. Increasing the amount of energy extracted per pulse requires increasing the mode area of the resonator that for the same cavity length causes exciting higher order transverse modes and decreasing the brightness of the output radiation. To suppress the higher order modes of these multimode resonators while maintaining the compact cavity requires the use of intra-cavity angular filters. A novel Q-switched laser design is presented using transmitting Bragg gratings (TBGs) as angular filters to suppress the higher order transverse modes. The laser consists of a 5 mm thick slab of Nd:YAG, a 3 mm thick slab of Cr:YAG with a 20% transmission, one TBG aligned to suppress the higher order modes along the x-axis, and a 40% output coupler. The gratings are recorded in photo-thermo-refractive (PTR) glass, which has a high damage threshold that can withstand both the high peak powers and high average powers present within the resonator. Using a 4.1 mrad TBG in a 10.8 mm long resonator with an 800μm x 400 μm pump beam, a nearly diffraction limited beam quality of M2 = 1.3 is obtained in a 0.76 mJ pulse with a pulse width of 614 ps.

  1. High-power high-brightness 808nm QCW laser diode mini bars

    Science.gov (United States)

    Huang, Hua; Wang, Jun; DeVito, Mark; Bao, Ling; Hodges, Aaron; Zhang, Shiguo; Wise, Damian; Grimshaw, Mike; Xu, Dapeng; Bai, Chendong

    2010-02-01

    A new class of high power high brightness 808 nm QCW laser diode mini bars has been developed. With nLight's nXLT facet passivation technology and improvements in epitaxial structure, mini bars of 3 mm bar width with high efficiency design have tested to over 280 W peak power with peak efficiency over 64% on conduction cooled CS packages, equivalent to output power density near 130 mW/μm. These mini laser bars open up new applications as compact, portable, and low current pump sources. Liftests have been carried out on conduction cooled CS packages and on QCW stacks. Over 370 million (M) shots lifetest with high efficiency design has been demonstrated on CS so far without failure, and over 80 M shots on QCW stacks with accelerated stress lifetest have also proven high reliability on mini bars with high temperature design. Failure analysis determined that the failure mechanism was related to bulk defects, showing that mini laser bars are not prone to facet failure, which is consistent with the large current pulse test and failure analysis on high power single emitters.

  2. ALMA Science Verification Data: Millimeter Continuum Polarimetry of the Bright Radio Quasar 3C 286

    CERN Document Server

    Nagai, H; Paladino, R; Hull, C L H; Cortes, P; Moellenbrock, G; Fomalont, E; Asada, K; Hada, K

    2016-01-01

    We present full-polarization observations of the compact, steep-spectrum radio quasar 3C~286 made with the ALMA at 1.3~mm. These are the first full-polarization ALMA observations, which were obtained in the framework of Science Verification. A bright core and a south-west component are detected in the total intensity image, similar to previous centimeter images. Polarized emission is also detected toward both components. The fractional polarization of the core is about 17\\%, this is higher than the fractional polarization at centimeter wavelengths, suggesting that the magnetic field is even more ordered in the millimeter radio core than it is further downstream in the jet. The observed polarization position angle (or EVPA) in the core is $\\sim$\\,$39^{\\circ}$, which confirms the trend that the EVPA slowly increases from centimeter to millimeter wavelengths. With the aid of multi-frequency VLBI observations, we argue that this EVPA change is associated with the frequency-dependent core position. We also report ...

  3. EXCEPTIONALLY BRIGHT TEV FLARES FROM THE BINARY LS I +61° 303

    Energy Technology Data Exchange (ETDEWEB)

    Archambault, S. [Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada); Archer, A.; Buckley, J. H.; Bugaev, V. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Aune, T.; Buchovecky, M. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Barnacka, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Benbow, W.; Cerruti, M. [Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States); Bird, R.; Collins-Hughes, E. [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Byrum, K. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D. [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Chen, X. [Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam-Golm (Germany); Ciupik, L. [Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States); Connolly, M. P. [School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Cui, W. [Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907 (United States); Dumm, J., E-mail: anna.ofaolain.de.bhroithe@desy.de [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); and others

    2016-01-20

    The TeV binary system LS I +61° 303 is known for its regular, non-thermal emission pattern that traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5% and 15% of the steady flux from the Crab Nebula (>300 GeV). In this article, VERITAS observations of LS I +61° 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. This is the brightest such activity from this source ever seen in the TeV regime. The strong outbursts have rise and fall times of less than a day. The short timescale of the flares, in conjunction with the observation of 10 TeV photons from LS I +61° 303 during the flares, provides constraints on the properties of the accelerator in the source.

  4. ALMA Science Verification Data: Millimeter Continuum Polarimetry of the Bright Radio Quasar 3C 286

    Science.gov (United States)

    Nagai, H.; Nakanishi, K.; Paladino, R.; Hull, C. L. H.; Cortes, P.; Moellenbrock, G.; Fomalont, E.; Asada, K.; Hada, K.

    2016-06-01

    We present full-polarization observations of the compact, steep-spectrum radio quasar 3C 286 made with the Atacama Large Millimeter and Submillimeter Array (ALMA) at 1.3 mm. These are the first full-polarization ALMA observations, which were obtained in the framework of Science Verification. A bright core and a south–west component are detected in the total intensity image, similar to previous centimeter images. Polarized emission is also detected toward both components. The fractional polarization of the core is about 17%; this is higher than the fractional polarization at centimeter wavelengths, suggesting that the magnetic field is even more ordered in the millimeter radio core than it is further downstream in the jet. The observed polarization position angle (or electric vector position angle (EVPA)) in the core is ˜39◦, which confirms the trend that the EVPA slowly increases from centimeter to millimeter wavelengths. With the aid of multi-frequency VLBI observations, we argue that this EVPA change is associated with the frequency-dependent core position. We also report a serendipitous detection of a sub-mJy source in the field of view, which is likely to be a submillimeter galaxy.

  5. Exceptionally Bright TeV Flares from the Binary LS I +61 303

    Science.gov (United States)

    Archambault, S.; Archer, A.; Aune, T.; Barnacka, A.; Benbow, W.; Bird, R.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Collins-Hughes, E.; Connolly, M. P.; Cui, W.; Dickinson, H. J.; Dumm, J.; Eisch, J. D.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortin, P.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Griffin, S.; Grube, J.; Gyuk, G.; Hütten, M.; Håkansson, N.; Hanna, D.; Holder, J.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krause, M.; Krennrich, F.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Millis, J.; Moriarty, P.; Mukherjee, R.; Nieto, D.; O'Brien, S.; O'Faoláin de Bhróithe, A.; Ong, R. A.; Otte, A. N.; Pandel, D.; Park, N.; Pelassa, V.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rousselle, J.; Rulten, C.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Smith, A. W.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Vincent, S.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; Zitzer, B.

    2016-01-01

    The TeV binary system LS I +61° 303 is known for its regular, non-thermal emission pattern that traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5% and 15% of the steady flux from the Crab Nebula (>300 GeV). In this article, VERITAS observations of LS I +61° 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. This is the brightest such activity from this source ever seen in the TeV regime. The strong outbursts have rise and fall times of less than a day. The short timescale of the flares, in conjunction with the observation of 10 TeV photons from LS I +61° 303 during the flares, provides constraints on the properties of the accelerator in the source.

  6. High brightness MEMS mirror based head-up display (HUD) modules with wireless data streaming capability

    Science.gov (United States)

    Milanovic, Veljko; Kasturi, Abhishek; Hachtel, Volker

    2015-02-01

    A high brightness Head-Up Display (HUD) module was demonstrated with a fast, dual-axis MEMS mirror that displays vector images and text, utilizing its ~8kHz bandwidth on both axes. Two methodologies were evaluated: in one, the mirror steers a laser at wide angles of mirror displays content on reflective multi-color emissive phosphor plates reflected off the windshield to create a virtual image for the driver. The display module is compact, consisting of a single laser diode, off-the-shelf lenses and a MEMS mirror in combination with a MEMS controller to enable precise movement of the mirror's X- and Y-axis. The MEMS controller offers both USB and wireless streaming capability and we utilize a library of functions on a host computer for creating content and controlling the mirror. Integration with smart phone applications is demonstrated, utilizing the mobile device both for content generation based on various messages or data, and for content streaming to the MEMS controller via Bluetooth interface. The display unit is highly resistant to vibrations and shock, and requires only ~1.5W to operate, even with content readable in sunlit outdoor conditions. The low power requirement is in part due to a vector graphics approach, allowing the efficient use of laser power, and also due to the use of a single, relatively high efficiency laser and simple optics.

  7. Exceptionally bright TeV flares from the binary LS I +61$^\\circ$ 303

    CERN Document Server

    Archambault, S; Aune, T; Barnacka, A; Benbow, W; Bird, R; Buchovecky, M; Buckley, J H; Bugaev, V; Byrum, K; Cardenzana, J V; Cerruti, M; Chen, X; Ciupik, L; Collins-Hughes, E; Connolly, M P; Cui, W; Dickinson, H J; Dumm, J; Eisch, J D; Falcone, A; Feng, Q; Finley, J P; Fleischhack, H; Flinders, A; Fortin, P; Fortson, L; Furniss, A; Gillanders, G H; Griffin, S; Grube, J; Gyuk, G; Huetten, M; Hakansson, N; Hanna, D; Holder, J; Humensky, T B; Johnson, C A; Kaaret, P; Kar, P; Kelley-Hoskins, N; Kertzman, M; Khassen, Y; Kieda, D; Krause, M; Krennrich, F; Kumar, S; Lang, M J; Maier, G; McArthur, S; McCann, A; Meagher, K; Millis, J; Moriarty, P; Mukherjee, R; Nieto, D; O'Brien, S; de Bhroithe, A O'Faolain; Ong, R A; Otte, A N; Pandel, D; Park, N; Pelassa, V; Pohl, M; Popkow, A; Pueschel, E; Quinn, J; Ragan, K; Reynolds, P T; Richards, G T; Roache, E; Rousselle, J; Rulten, C; Santander, M; Sembroski, G H; Shahinyan, K; Smith, A W; Staszak, D; Telezhinsky, I; Tucci, J V; Tyler, J; Vincent, S; Wakely, S P; Weiner, O M; Weinstein, A; Wilhelm, A; Williams, D A; Zitzer, B

    2016-01-01

    The TeV binary system LS I +61$^\\circ$ 303 is known for its regular, non-thermal emission pattern which traces the orbital period of the compact object in its 26.5 day orbit around its B0 Ve star companion. The system typically presents elevated TeV emission around apastron passage with flux levels between 5% and 15% of the steady flux from the Crab Nebula (> 300 GeV). In this article, VERITAS observations of LS I +61$^\\circ$ 303 taken in late 2014 are presented, during which bright TeV flares around apastron at flux levels peaking above 30% of the Crab Nebula flux were detected. This is the brightest such activity from this source ever seen in the TeV regime. The strong outbursts have rise and fall times of less than a day. The short timescale of the flares, in conjunction with the observation of 10 TeV photons from LS I +61$^\\circ$ 303 during the flares, provides constraints on the properties of the accelerator in the source.

  8. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    Energy Technology Data Exchange (ETDEWEB)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States)

    2014-06-10

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ({sup f}licker{sup )} of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T {sub eff} = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested.

  9. Ion diffusion in compacted bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Lehikoinen, J. [VTT Chemical Technology, Espoo (Finland)

    1999-03-01

    In the study, a two-dimensional molecular-level diffusion model, based on a modified form of the Gouy-Chapman (GC) theory of the electrical double layers, for hydrated ionic species in compacted bentonite was developed. The modifications to the GC theory, which forms the very kernel of the diffusion model, stem from various non-conventional features: ionic hydration, dielectric saturation, finite ion-sizes and specific adsorption. The principal objectives of the study were met. With the aid of the consistent diffusion model, it is a relatively simple matter to explain the experimentally observed macroscopic exclusion for anions as well as the postulated, but greatly controversial, surface diffusion for cations. From purely theoretical grounds, it was possible to show that the apparent diffusivities of cations, anions and neutral molecules (i) do not exhibit order-or-magnitude differences, and (ii) are practically independent of the solution ionic strength used and, consequently, of the distribution coefficient, K{sub d}, unless they experience specific binding onto the substrate surface. It was also of interest to investigate the equilibrium anionic concentration distribution in the pore geometry of the GMM model as a function of the solution ionic strength, and to briefly speculate its consequences to diffusion. An explicit account of the filter-plate effect was taken by developing a computerised macroscopic diffusion model, which is based upon the very robust and efficient Laplace Transform Finite-Difference technique. Finally, the inherent limitations as well as the potential fields of applications of the models were addressed. (orig.) 45 refs.

  10. A compact tritium AMS system

    Energy Technology Data Exchange (ETDEWEB)

    Chiarappa, M L; Dingley, K H; Hamm, R W; Love, A H; Roberts, M L

    1999-09-23

    Tritium ({sup 3}H) is a radioisotope that is extensively utilized in biological and environmental research. For biological research, {sup 3}H is generally quantified by liquid scintillation counting requiring gram-sized samples and counting times of several hours. For environmental research, {sup 3}H is usually quantified by {sup 3}He in-growth which requires gram-sized samples and in-growth times of several months. In contrast, provisional studies at LLNL's Center for Accelerator Mass Spectrometry have demonstrated that Accelerator Mass Spectrometry (AMS) can be used to quantify {sup 3}H in milligram-sized biological samples with a 100 to 1000-fold improvement in detection limits when compared to scintillation counting. This increased sensitivity is expected to have great impact in the biological and environmental research community. However in order to make the {sup 3}H AMS technique more broadly accessible, smaller, simpler, and less expensive AMS instrumentation must be developed. To meet this need, a compact, relatively low cost prototype {sup 3}H AMS system has been designed and built based on a LLNL ion source/sample changer and an AccSys Technology, Inc. Radio Frequency Quadrupole (RFQ) linac. With the prototype system, {sup 3}/{sup 1}H ratios ranging from 1 x 10{sup -10} to 1 x 10{sup -13} have to be measured from milligram sized samples. With improvements in system operation and sample preparation methodology, the sensitivity limit of the system is expected to increase to approximately 1 x 10{sup -15}.

  11. On the Compactly Locally Uniformly Rotund Points of Orlicz Spaces

    Indian Academy of Sciences (India)

    Lili Chen; Yunan Cui

    2007-11-01

    In this paper, locally uniformly rotund points and compactly locally uniformly rotund points are introduced. Moreover, criteria for compactly locally uniformly rotund points in Orlicz spaces are given.

  12. The relationship between brightness temperature and soil moisture. Selection of frequency range for microwave remote sensing

    International Nuclear Information System (INIS)

    The analysis of brightness temperature data acquired from field and aircraft experiments demonstrates a linear relationship between soil moisture and brightness temperature. However, the analysis of brightness temperature data acquired by the Skylab radiometer demonstrates a non-linear relationship between soil moisture and brightness temperature. In view of the above and also because of recent theoretical developments for the calculation of the dielectric constant and brightness temperature under varying soil moisture profile conditions, an attempt is made to study the theoretical relationship between brightness temperature and soil moisture as a function of frequency. Through the above analysis, the appropriate microwave frequency range for soil moisture studies is recommended

  13. An imaging and spectroscopic study of the very metal-deficient blue compact dwarf galaxy Tol 1214--277

    CERN Document Server

    Fricke, K J; Papaderos, P; Guseva, N G; Thuan, T X

    2001-01-01

    We present a spectrophotometric study based on VLT/FORS I observations of one of the most metal-deficient blue compact dwarf (BCD) galaxies known, Tol 1214-277 (Z ~ Zsun/25). The data show that roughly half of the total luminosity of the BCD originates from a bright and compact starburst region located at the northeastern tip of a faint dwarf galaxy with cometary appearance. The starburst has ignited less than 4 Myr ago and its emission is powered by several thousands O7V stars and ~ 170 late-type nitrogen Wolf-Rayet stars located within a compact region with < 500 pc in diameter. For the first time in a BCD, a relatively strong [Fe V] 4227 emission line is seen which together with intense He II 4686 emission indicates the presence of a very hard radiation field in Tol 1214-277. We argue that this extraordinarily hard radiation originates from both Wolf--Rayet stars and radiative shocks in the starburst region. The structural properties of the low-surface-brightness (LSB) component underlying the starburst...

  14. Compact 2 Micron Seed Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of new compact, high power and extremely reliable 2 micron seed laser using newly developed Tm3+ doped germanate glass fibers,...

  15. Controlled Compact High Voltage Power Lines

    Directory of Open Access Journals (Sweden)

    Postolati V.

    2016-04-01

    Full Text Available Nowadays modern overhead transmission lines (OHL constructions having several significant differences from conventional ones are being used in power grids more and more widely. Implementation of compact overhead lines equipped with FACTS devices, including phase angle regulator settings (compact controlled OHL, appears to be one of the most effective ways of power grid development. Compact controlled AC HV OHL represent a new generation of power transmission lines embodying recent advanced achievements in design solutions, including towers and insulation, together with interconnection schemes and control systems. Results of comprehensive research and development in relation to 110–500kV compact controlled power transmission lines together with theoretical basis, substantiation, and methodological approaches to their practical application are presented in the present paper.

  16. Compact MCP assemblies for mass spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, S. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Umebayashi, S. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Kusuyama, Y. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Natsume, Y. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.; Oba, K. [Hamamatsu Photonics K.K., Shizuoka (Japan). Electron Tube Div.

    1995-09-01

    We have developed compact microchannel plate (MCP) assemblies which have a high gain, good pulse height resolution and a fast response for MS applications. In this paper, these new assemblies are described referring to their structures, functions and characteristics. (orig.).

  17. The Compact Pulsed Hadron Source Construction Status

    CERN Document Server

    Wei, Jie; Cai, Jinchi; Chen, Huaibi; Cheng, Cheng; Du, Qiang; Du, Taibin; Feng, Qixi; Feng, Zhe; Gong, Hui; Guan, Xialing; Han, Xiaoxue; Huang, Tuchen; Huang, Zhifeng; Li, Renkai; Li, Wenqian; Loong, Chun-Keung; Tang, Chuanxiang; Tian, Yang; Wang, Xuewu; Xie, Xiaofeng; Xing, Qingzi; Xiong, Zhengfeng; Xu, Dong; Yang, Yigang; Zeng, Zhi; Zhang, Huayi; Zhang, Xiaozhang; Zheng, Shu-xin; Zheng, Zhihong; Zhong, Bin; Billen, James; Young, Lloyd; Fu, Shinian; Tao, Juzhou; Zhao, Yaliang; Guan, Weiqiang; He, Yu; Li, Guohua; Li, Jian; Zhang, Dong-sheng; Li, Jinghai; Liang, Tianjiao; Liu, Zhanwen; Sun, Liangting; Zhao, Hongwei; Shao, Beibei; Stovall, James

    2010-01-01

    This paper reports the design and construction status, technical challenges, and future perspectives of the proton-linac based Compact Pulsed Hadron Source (CPHS) at the Tsinghua University, Beijing, China

  18. Compact 2 Micron Seed Laser Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of innovative compact, high power and extremely reliable 2 micron seed laser using newly developed Tm3+ doped germanate glass...

  19. Local compactness in approach spaces II

    Directory of Open Access Journals (Sweden)

    R. Lowen

    2003-01-01

    Full Text Available This paper studies the stability properties of the concepts of local compactness introduced by the authors in 1998. We show that all of these concepts are stable for contractive, expansive images and for products.

  20. Effect of Subsoil Compaction on Hydraulic Parameters

    DEFF Research Database (Denmark)

    Iversen, Bo Vangsø; Berisso, Feto Esimo; Schjønning, Per;

    effects of subsoil compaction on soil ecological services and functions) put forward the hypothesis that due to a decrease in the hydraulic conductivity in the soil matrix, compaction increases the frequency of preferential flow events in macropores and therefore increases the leaching of otherwise....... In the field the near-saturated hydraulic conductivity was measured with a tension infiltrometer in the same treatments at a depth of 30 cm. In the laboratory saturated and near-saturated hydraulic conductivity and the bulk density were measured as well. Also, macropores in the large soil cores were made...... that for the upper soil depth, a significant increase in bulk density was measured for the compacted treatment. For the lower depth differences were less pronounced. For the saturated hydraulic conductivity, the results indicated a decrease of the hydraulic conductivity for the compacted treatment for the upper...

  1. Compact Fiber Lasers for Coherent LIDAR Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This is a proposal to investigate the feasibility of developing a low cost, compact, lightweight, high power (>500m W) and narrow linewidth 1.5 and 1.06 micron...

  2. Deep Compaction Control of Sandy Soils

    Directory of Open Access Journals (Sweden)

    Bałachowski Lech

    2015-02-01

    Full Text Available Vibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation of CPTU/DMT can be used to take into account vertical and horizontal stress and void ratio effects. Some examples of interpretation of soundings in pre-treated and compacted sands are given. Some acceptance criteria for compaction control are discussed. The improvement factors are analysed including the normalised approach based on the soil behaviour type index.

  3. Diagnostics for the National Compact Stellarator Experiment

    International Nuclear Information System (INIS)

    The status of planning of the National Compact Stellarator Experiment (NCSX) diagnostics is presented, with the emphasis on resolution of diagnostics access issues and on diagnostics required for the early phases of operation

  4. The Role of Clustering of Sub-Clumps in Bright Elliptical Galaxy Formation from a Low-Spin Seed Galaxy

    CERN Document Server

    Kawata, D

    2001-01-01

    We reveal the role of clustering of sub-clumps, which is expected in the cold dark matter (CDM) universe, in forming a bright elliptical galaxy (BEG) from a low-spin seed galaxy. This can be done by comparing the evolution of a low-spin seed galaxy including small-scale density fluctuations expected in the CDM universe (Model 1) with that of a completely uniform one (Model 2), using numerical experiments. We show that Model 2 cannot reproduce the properties of BEGs and forms a disk which is too compact and too bright due to the conservation of the initial-small angular momentum. In Model 1 clustering of the sub-clumps caused by initial small-scale density fluctuations leads to angular momentum transfer from the baryon component to the dark matter and consequently a nearly spherical system supported by random motions is formed. Moreover the collisionless property of the stars formed in the sub-clumps prevents the dissipative contraction of the system, leading to a large measured half-light radius. As a result,...

  5. Selected problems in astrophysics of compact objects

    OpenAIRE

    Sedrakian, Armen

    2012-01-01

    I review three problems in astrophysics of compacts stars: (i) the phase diagram of warm pair-correlated nuclear matter a sub-saturation densities at finite isospin asymmtery; (ii) the Standard Model neutrino emission from superfluid phases in neutron stars within the Landau theory of Fermi (superfluid) liquids; (iii) the beyond Standard Model physics of axionic cooling of compact stars by the Cooper pair-breaking processes.

  6. Cc (X) Spaces with X Locally Compact

    Institute of Scientific and Technical Information of China (English)

    J. C. FERRANDO; S. MOLL

    2007-01-01

    In this paper, we show, among other results, that if X is a [separable] locally compact space X [satisfying the first countability axiom] then the space Cc (X) has countable tightness [if and only if it has bounding tightness] if and only if it is Fréchet-Urysohn, if and only if Cc (X) contains a dense (LM) subspace and if and only if X is σ-compact.

  7. Compact Weighted Composition Operators on Function Algebras

    OpenAIRE

    TAKAGI, Hiroyuki

    1988-01-01

    A weighted endomorphism of an algebra is an endomorphism followed by a multiplier. In [6] and [4], H. Kamowitz characterized compact weighted endomorphisms of $C(X)$ and the disc algebra. In this note we define a weighted composition operator on a function algebra as a generalization of a weighted endomorphism, and characterize compact weighted composition operators on a function algebra satisfying a certain condition [Theorem 2]. This theorem not only includes Kamowitz's results as ...

  8. Parahoric bundles on a compact Riemann surface

    CERN Document Server

    Balaji, V

    2010-01-01

    Let $X$ be a compact Riemann surface of genus $g \\geq 2$. The aim of this paper is to study homomorphisms of certain discrete subgroups of $PSL(2, {\\mathbb R})$ into maximal compact subgroups of semisimple simply connected algebraic groups and relate them to torsors under a Bruhat-Tits group scheme. We also construct the moduli spaces of semistable parahoric bundles. These results generalize the theorem of Mehta and Seshadri on parabolic vector bundles.

  9. Compact Modelling Of Double-Gate MOSFET

    OpenAIRE

    2009-01-01

    The requirements for high precision and high speed of compact models demand new approaches to old challenges while raising new ones. In this paper I investigate the following: DG MOS Transistor modelling for integrated circuit design; Applications of conformal mapping to compact modelling; How this technique can be applied to model DG MOS Transistor; Prerequisites for a valid SPICE-like model of this device.

  10. Compaction of Ductile and Fragile Grains

    Science.gov (United States)

    Creissac, S.; Pouliquen, O.; Dalloz-Dubrujeaud, B.

    2009-06-01

    The compaction of powders into tablets is widely used in several industries (cosmetics, food, pharmaceutics…). In all these industries, the composition of the initial powder is complex, and the behaviour under compaction is not well known, also the mechanical behaviour of the tablets. The aim of this paper is to understand the behaviour (pressure vs density) of a simplified media made of fragile and ductile powders, varying the relative ratio of each powder. Some compaction experiments were carried out with glass beads (fragile) and Polyethylen Glycol powder (ductile). We observe two typical behaviours, depending on the relative volumic fraction of each component. A transition is pointed out, observing the evolution of the slope of the curve pressure/density. This transition is explained by geometrical considerations during compaction. A model is proposed, based on the assumption that the studied media can be compare to a diphasic material with a continuous phase (the ductile powder) and a discrete phase (the fragile powder). The result of this model is compare to the experimental results of compaction, and give a good prediction of the behaviour of the different mixing, knowing the behaviour of the ductile and the fragile phase separately. These results were also interpreted in terms of Heckel parameter which characterizes the ability of the powder to deform plastically under compaction. Some mechanical tests were also performed to compare the mechanical resitance of the obtained tablets.

  11. Technology Selections for Cylindrical Compact Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey A. Phillips

    2010-10-01

    A variety of process approaches are available and have been used historically for manufacture of cylindrical fuel compacts. The jet milling, fluid bed overcoating, and hot press compacting approach being adopted in the U.S. AGR Fuel Development Program for scale-up of the compacting process involves significant paradigm shifts from historical approaches. New methods are being pursued because of distinct advantages in simplicity, yield, and elimination of process mixed waste. Recent advances in jet milling technology allow simplified dry matrix powder preparation. The matrix preparation method is well matched with patented fluid bed powder overcoating technology recently developed for the pharmaceutical industry and directly usable for high density fuel particle matrix overcoating. High density overcoating places fuel particles as close as possible to their final position in the compact and is matched with hot press compacting which fully fluidizes matrix resin to achieve die fill at low compacting pressures and without matrix end caps. Overall the revised methodology provides a simpler process that should provide very high yields, improve homogeneity, further reduce defect fractions, eliminate intermediate grading and QC steps, and allow further increases in fuel packing fractions.

  12. Dynamic compaction of tungsten carbide powder.

    Energy Technology Data Exchange (ETDEWEB)

    Gluth, Jeffrey Weston; Hall, Clint Allen; Vogler, Tracy John; Grady, Dennis Edward

    2005-04-01

    The shock compaction behavior of a tungsten carbide powder was investigated using a new experimental design for gas-gun experiments. This design allows the Hugoniot properties to be measured with reasonably good accuracy despite the inherent difficulties involved with distended powders. The experiments also provide the first reshock state for the compacted powder. Experiments were conducted at impact velocities of 245, 500, and 711 m/s. A steady shock wave was observed for some of the sample thicknesses, but the remainder were attenuated due to release from the back of the impactor or the edge of the sample. The shock velocity for the powder was found to be quite low, and the propagating shock waves were seen to be very dispersive. The Hugoniot density for the 711 m/s experiment was close to ambient crystal density for tungsten carbide, indicating nearly complete compaction. When compared with quasi-static compaction results for the same material, the dynamic compaction data is seen to be significantly stiffer for the regime over which they overlap. Based on these initial results, recommendations are made for improving the experimental technique and for future work to improve our understanding of powder compaction.

  13. Compact fission counter for DANCE

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C Y; Chyzh, A; Kwan, E; Henderson, R; Gostic, J; Carter, D; Bredeweg, T; Couture, A; Jandel, M; Ullmann, J

    2010-11-06

    counter and still be able to maintain a stable operation under extreme radioactivity and the ability to separate fission fragments from {alpha}'s. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.

  14. Compact fission counter for DANCE

    International Nuclear Information System (INIS)

    operation under extreme radioactivity and the ability to separate fission fragments from α's. In the following sections, the description is given for the design and performance of this new compact PPAC, for studying the neutron-induced reactions on actinides using DANCE at LANL.

  15. National compacts to reduce deforestation

    Energy Technology Data Exchange (ETDEWEB)

    Santilli, M. [Instituto Socioambiental ISA., Brasilia DF (Brazil); Moutinho, P.; Nepstad, D. [Instituto de Pesquisa Ambiental da Amazonia IPAM, Belem (Brazil)

    2005-07-01

    countries in emissions reductions efforts, in exchange for palpable economic benefit. However, tropical deforestation results from diverse economic, political and social factors - and actors - which vary according to specific regional and national scenarios. It thus makes no sense to imagine general rules and procedures to orient action to reduce deforestation. Countries interested in international compensation for reducing deforestation should be willing, and be supported and encouraged, to define their own strategies, according to the specific conditions in which deforestation occurs in each region. This article, then, intends to imagine the possible outlines of a potential national compact for reducing tropical deforestation, taking Brazil, the world's largest emitter in this area, as an example. Deforestation in the Brazilian Amazon, which makes up the majority of these emissions ({approx}3% of global emissions) forms the basis of this analysis. The National Institute for Space Research has collected and analyzed historical series of satellite data for the region.

  16. Microwave brightness temperature imaging and dielectric properties of lunar soil

    Indian Academy of Sciences (India)

    Wu Ji; Li Dihui; Zhang Xiaohui; Jiang Jingshan; A T Altyntsev; B I Lubyshev

    2005-12-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become attractive due to the existence of He3 and ilmenite in the lunar soil and their possible utilization as nuclear fuel for power generation.Although the composition of the lunar surface soil can be determined by optical and /X-ray spectrometers, etc., the evaluation of the total reserves of He3 and ilmenite within the regolith and in the lunar interior are still not available.In this paper,we give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 meter Telescope and Siberian Solar Radio Telescope.We also present the results of the microwave dielectric properties of terrestrial analogues of lunar soil and,discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  17. Bright solitons in a PT-symmetric chain of dimers

    CERN Document Server

    Kirikchi, Omar B; Susanto, Hadi

    2016-01-01

    We study the existence and stability of fundamental bright discrete solitons in a parity-time (PT)-symmetric coupler composed by a chain of dimers, that is modelled by linearly coupled discrete nonlinear Schrodinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anti-continuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, on the contrary of the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quart...

  18. Extremely High Current, High-Brightness Energy Recovery Linac

    CERN Document Server

    Ben-Zvi, Ilan; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Grimes, Jacob T; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Lambiase, Robert; Litvinenko, Vladimir N; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Segalov, Zvi; Smith, Kevin T; Todd, Alan M M; Warren-Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  19. The brightness and spatial distributions of terrestrial radio sources

    CERN Document Server

    Offringa, A R; Zaroubi, S; Koopmans, L V E; Wijnholds, S J; Abdalla, F B; Brouw, W N; Ciardi, B; Iliev, I T; Harker, G J A; Mellema, G; Bernardi, G; Zarka, P; Ghosh, A; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Beck, R; Bell, M E; Bell, M R; Bentum, M J; Best, P; Bîrzan, L; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; de Gasperin, F; de Geus, E; de Vos, M; Duscha, S; Eislöffel, J; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Grießmeier, J; Hassall, T E; Horneffer, A; Iacobelli, M; Juette, E; Karastergiou, A; Klijn, W; Kondratiev, V I; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Loose, M; Maat, P; Macario, G; Mann, G; McKean, J P; Meulman, H; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Rafferty, D; Reich, W; van Nieuwpoort, R; Röttgering, H; Scaife, A M M; Sluman, J; Smirnov, O; Sobey, C; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Toribio, C; Vermeulen, R; Vocks, C; van Weeren, R J; Wise, M W; Wucknitz, O

    2013-01-01

    Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obstruct the detection of the weak astronomical signals of interest. This issue is especially important for Epoch of Reionisation (EoR) projects that try to detect the faint redshifted HI signals from the time of the earliest structures in the Universe. We explore the RFI situation at 30-163 MHz by studying brightness histograms of visibility data observed with LOFAR, similar to radio-source-count analyses that are used in cosmology. An empirical RFI distribution model is derived that allows the simulation of RFI in radio observations. The brightness histograms show an RFI distribution that follows a power-law distribution with an estimated exponent around -1.5. With several assumptions, this can be explained with a uniform distribution of terrestrial radio sources whose radiation follows existing propagation models. Extrapolation of t...

  20. Histogram Equalization with Range Offset for Brightness Preserved Image Enhancement

    Directory of Open Access Journals (Sweden)

    Haidi Ibrahim

    2011-12-01

    Full Text Available In this paper, a simple modification to Global Histogram Equalization (GHE, a well known digital image enhancement method, has been proposed. This proposed method known as Histogram Equalization with Range Offset (HERO is divided into two stages. In its first stage, an intensity mapping function is constructed by using the cumulative density function of the input image, similar to GHE. Then, during the second stage, an offset for the intensity mapping function will be determined to maintain the mean brightness of the image, which is a crucial criterion for digital image enhancement in consumer electronic products. Comparison with some of the current histogram equalization based enhancement methods shows that HERO successfully preserves the mean brightness and give good enhancement to the image.

  1. A ROSAT Bright Source Catalog Survey with the Swift Satellite

    CERN Document Server

    Fox, D B

    2004-01-01

    We consider the prospects for a complete survey of the 18,811 sources of the ROSAT All-Sky Survey Bright Source Catalog (BSC) with NASA's Swift gamma-ray burst (GRB) mission. By observing each BSC source for 500 s with the satellite's imaging X-ray and UV/optical telescopes, this "Swift Bright (Source) Catalog Survey" (Swift-BCS) would derive ~20 mCrab, 10-100 keV) with the wide-field Burst Alert Telescope (BAT); and a two-year all-sky BAT survey down to >~1 mCrab. The resulting expansion of the catalog of identified X-ray sources from 2000 to 18,000 will provide a greatly-enriched set of targets for observation by XMM-Newton, Chandra, and future high-energy observatories.

  2. BRITE-Constellation: Nanosatellites for Precision Photometry of Bright Stars

    CERN Document Server

    Weiss, W W; Schwarzenberg-Czerny, A; Koudelka, O F; Grant, C C; Zee, R E; Kuschnig, R; Mochnacki, St; Rucinski, S M; Matthews, J M; Orleanski, P; Pamyatnykh, A; Pigulski, A; Alves, J; Guedel, M; Handler, G; Wade, G A; Scholtz, A L

    2013-01-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, brightness and temperature variations of stars brighter than V = 4. The current mission design consists of three pairs of 7 kg nanosats from Austria, Canada and Poland carrying optical telescopes and CCDs. One instrument in each pair is equipped with a blue filter; the other, a red filter. The first two nanosats are UNIBRITE, designed and built by University of Toronto Institute for Aerospace Studies - Space Flight Laboratory and its twin, BRITE-Austria, built by the Technical University Graz with support of UTIAS-SFL. They were launched on 25 February 2013 by the Indian Space Agency under contract to the Canadian Space Agency into a low-Earth dusk-dawn polar orbit.

  3. Cometary activity in 2060 Chiron at minimum brightness

    CERN Document Server

    Silva, A M; Silva, Adrian M.; Cellone, Sergio A.

    2001-01-01

    We present two-colour CCD imaging of 2060 Chiron obtained between 1996 and 1998 with the 2.15 m telescope at CASLEO (San Juan, Argentina). These post-perihelion observations show that Chiron was then near its historical brightness minima, however a coma was clearly detected. The dynamical state of the coma is studied by means of azimuthally averaged surface brightness profiles, which show the signatures of radiation pressure on the dust grain distribution. Aperture photometry shows an achromatic dimming with an amplitude \\~ 0.09 mag in approximately one hour. If due to rotation of the nucleus, this rather high amplitude is used to derive a new value for the nuclear magnitude, m_0 ~ 6.80 mag.

  4. Microwave Brightness Temperature and Lunar Son Dielectric Property Retrieve

    Institute of Scientific and Technical Information of China (English)

    J. Wu; D.H. Li; A.T. Altyntsev; B.I. Lubyshev

    2005-01-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer, γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  5. Sunspot bright rings and the thermal diffusivity of solar convection

    Science.gov (United States)

    Duvall, T., Jr.; Fowler, L. A.; Foukal, P.

    1983-01-01

    Raster-scan observations of 10 sunspots, made in 1980 and 1981 with the 512-channel diode array and vacuum telescope at the Kitt Peak National Observatory, are reported. Data from several 10-min scans of 0.25-A passbands of clean continuum were summed to give an rms noise level of 0.25 percent, corrected by applying a limb-darkening curve, and analyzed to determine the average intensity for each of eight segments of a series of concentric rings around each sunspot. Faculae and pores were identified and discarded in constructing radial intensity profiles. Marginally significant bright symmetric rings (peak amplitude 0.1-0.3 percent) not attributable to residual facular signal or instrumental effects were observed around 6 of 10 sunspots. No evidence of more intense bright rings was found. These findings are discussed in terms of thermal-diffusion models proposed to explain the fate of the radiative flux blocked by sunspots.

  6. Operational Performance Improvements to BRIght Target Explorer Constellation

    Science.gov (United States)

    Choi, Seung Yun

    The BRIght Target Explorer (BRITE)-Constellation is composed of six nano-satellites funded by Austria, Canada, and Poland, and each of them is equipped with an optical telescope that observes stars with visual magnitude +3.5 or brighter. BRITE-Constellation has provided numerous images of bright stars from Low Earth Orbit, which will eventually lead to investigation of origin of the Universe. This thesis presents the contribution of the author to BRITE mission, especially in BRITE Operations. The author performed antenna steering experiments on UniBRITE and BRITE-Toronto, to improve data downlink. To improve scientific data collection from BRITE satellites, the author computed available observation time for multiple targets every orbit, which resulted in collection of twice the amount of scientific data. Also, the author increased the available observation time for each target from 32 minutes to 48 minutes by improving the performance of the star tracker on-board BRITE-Toronto.

  7. Sobolev Spaces on Locally Compact Abelian Groups: Compact Embeddings and Local Spaces

    Directory of Open Access Journals (Sweden)

    Przemysław Górka

    2014-01-01

    Full Text Available We continue our research on Sobolev spaces on locally compact abelian (LCA groups motivated by our work on equations with infinitely many derivatives of interest for string theory and cosmology. In this paper, we focus on compact embedding results and we prove an analog for LCA groups of the classical Rellich lemma and of the Rellich-Kondrachov compactness theorem. Furthermore, we introduce Sobolev spaces on subsets of LCA groups and study its main properties, including the existence of compact embeddings into Lp-spaces.

  8. Production of strongly bound 39K bright solitons

    CERN Document Server

    Lepoutre, S; Boissé, A; Berthet, G; Salomon, G; Aspect, A; Bourdel, T

    2016-01-01

    We report on the production of 39 K matter-wave bright solitons, i.e., 1D matter-waves that propagate without dispersion thanks to attractive interactions. The volume of the soliton is studied as a function of the scattering length through three-body losses, revealing peak densities as high as $\\sim 5 \\times 10^{20} m^{-3}$. Our solitons, close to the collapse threshold, are strongly bound and will find applications in fundamental physics and atom interferometry.

  9. Algebraic bright and vortex solitons in defocusing media

    OpenAIRE

    Borovkova, Olga V.; Kartashov, Yaroslav V.; Boris A. Malomed; Torner, Lluis

    2011-01-01

    We demonstrate that spatially inhomogeneous defocusing nonlinear landscapes with the nonlinearity coefficient growing toward the periphery as [1+abs(r)]**a support one- and two-dimensional fundamental and higher-order bright solitons, as well as vortex solitons, with algebraically decaying tails. The energy flow of the solitons converges as long as nonlinearity growth rate exceeds the dimensionality, i.e., a>D. Fundamental solitons are always stable, while multipoles and vortices are stable i...

  10. Hybrid bright-field and hologram imaging of cell dynamics

    Science.gov (United States)

    Byeon, Hyeokjun; Lee, Jaehyun; Doh, Junsang; Lee, Sang Joon

    2016-09-01

    Volumetric observation is essential for understanding the details of complex biological phenomena. In this study, a bright-field microscope, which provides information on a specific 2D plane, and a holographic microscope, which provides information spread over 3D volumes, are integrated to acquire two complementary images simultaneously. The developed system was successfully applied to capture distinct T-cell adhesion dynamics on inflamed endothelial layers, including capture, rolling, crawling, transendothelial migration, and subendothelial migration.

  11. Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model

    Science.gov (United States)

    Duriscoe, Dan M.

    2013-11-01

    Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth's surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution.

  12. High-brightness switchable multiwavelength remote laser in air

    Energy Technology Data Exchange (ETDEWEB)

    Yao Jinping; Cheng Ya; Xu Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zeng Bin; Li Guihua; Chu Wei; Ni Jielei; Zhang Haisu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Xu Huailiang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Chin, See Leang [Center for Optics, Universite Laval, Quebec City, Quebec G1V 0A6 (Canada)

    2011-11-15

    We demonstrate a harmonic-seeded switchable multiwavelength laser in air driven by intense midinfrared femtosecond laser pulses, in which population inversion occurs at an ultrafast time scale (i.e., less than {approx}200 fs) owing to direct formation of excited molecular nitrogen ions by strong-field ionization of inner-valence electrons. The bright multiwavelength laser in air opens the perspective for remote detection of multiple pollutants based on nonlinear optical spectroscopy.

  13. The Morphology of Low Surface Brightness Disk Galaxies

    Science.gov (United States)

    McGaugh, S.; Schombert, J.; Bothun, G.

    1994-01-01

    Images of a sample of low surface brightness (LSB) disk galaxies are presented. These galaxies are generally late types; however, they are not dwarfs, being intrinsically large and luminous. The morphology of LSB galaxies is discussed in terms of the physical interpretation of the Hubble sequence, the stages of which are found to be nonlinear in the sense that smaller physical differences separate mid to early type spirals than late types.

  14. Survival analysis of the optical brightness of GRB host galaxies

    CERN Document Server

    Racz, I I; Bagoly, Z; Toth, L V

    2015-01-01

    We studied the unbiased optical brightness distribution which was calculated from the survival analysis of host galaxies and its relationship with the Swift GRB data of the host galaxies observed by the Keck telescopes. Based on the sample obtained from merging the Swift GRB table and the Keck optical data we also studied the dependence of this distribution on the data of the GRBs. Finally, we compared the HGs distribution with standard galaxies distribution which is in the DEEP2 galaxies catalog.

  15. Brightness/darkness induction and the genesis of a contour

    Science.gov (United States)

    Roncato, Sergio

    2014-01-01

    Visual contours often result from the integration or interpolation of fragmented edges. The strength of the completion increases when the edges share the same contrast polarity (CP). Here we demonstrate that the appearance in the perceptual field of this integrated unit, or contour of invariant CP, is concomitant with a vivid brightness alteration of the surfaces at its opposite sides. To observe this effect requires some stratagems because the formation in the visual field of a contour of invariant CP normally engenders the formation of a second contour and then the rise of two streams of induction signals that interfere in different ways. Particular configurations have been introduced that allow us to observe the induction effects of one contour taken in isolation. I documented these effects by phenomenological observations and psychophysical measurement of the brightness alteration in relation to luminance contrast. When the edges of the same CP complete to form a contour, the background of homogeneous luminance appears to dim at one side and to brighten at the opposite side (in accord with the CP). The strength of the phenomenon is proportional to the local luminance contrast. This effect weakens or nulls when the contour of the invariant CP separates surfaces filled with different gray shades. These conflicting results stimulate a deeper exploration of the induction phenomena and their role in the computation of brightness contrast. An alternative perspective is offered to account for some brightness illusions and their relation to the phenomenal transparency. The main assumption asserts that, when in the same region induction signals of opposite CP overlap, the filling-in is blocked unless the image is stratified into different layers, one for each signal of the same polarity. Phenomenological observations document this “solution” by the visual system. PMID:25368570

  16. The brightness and spatial distributions of terrestrial radio sources

    OpenAIRE

    Offringa, A. R.; De Bruyn, A. G.; Zaroubi, S.; Koopmans, L. V. E.; Wijnholds, S. J.; Abdalla, F. B.; Brouw, W. N.; Ciardi, B.; Iliev, I. T.; Harker, G. J. A.; Mellema, G.; Bernardi, G.; Zarka, P.; Ghosh, A; Alexov, A.

    2013-01-01

    Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obstruct the detection of the weak astronomical signals of interest. This issue is especially important for Epoch of Reionisation (EoR) projects that try to detect the faint redshifted HI signals from the time of the earliest structures in the Universe. We explore the RFI situation at 30-163 MHz by studying brightness ...

  17. Distance Measurements and Stellar Population Properties via Surface Brightness Fluctuations

    OpenAIRE

    Fritz, Alexander

    2012-01-01

    Surface Brightness Fluctuations (SBFs) are one of the most powerful techniques to measure the distance and to constrain the unresolved stellar content of extragalactic systems. For a given bandpass, the absolute SBF magnitude \\bar{M} depends on the properties of the underlying stellar population. Multi-band SBFs allow scientists to probe different stages of the stellar evolution: UV and blue wavelength band SBFs are sensitive to the evolution of stars within the hot Horizontal Branch (HB) and...

  18. Bright spots among the world’s coral reefs

    Science.gov (United States)

    Cinner, Joshua E.; Huchery, Cindy; MacNeil, M. Aaron; Graham, Nicholas A. J.; McClanahan, Tim R.; Maina, Joseph; Maire, Eva; Kittinger, John N.; Hicks, Christina C.; Mora, Camilo; Allison, Edward H.; D'Agata, Stephanie; Hoey, Andrew; Feary, David A.; Crowder, Larry; Williams, Ivor D.; Kulbicki, Michel; Vigliola, Laurent; Wantiez, Laurent; Edgar, Graham; Stuart-Smith, Rick D.; Sandin, Stuart A.; Green, Alison L.; Hardt, Marah J.; Beger, Maria; Friedlander, Alan; Campbell, Stuart J.; Holmes, Katherine E.; Wilson, Shaun K.; Brokovich, Eran; Brooks, Andrew J.; Cruz-Motta, Juan J.; Booth, David J.; Chabanet, Pascale; Gough, Charlie; Tupper, Mark; Ferse, Sebastian C. A.; Sumaila, U. Rashid; Mouillot, David

    2016-07-01

    Ongoing declines in the structure and function of the world’s coral reefs require novel approaches to sustain these ecosystems and the millions of people who depend on them. A presently unexplored approach that draws on theory and practice in human health and rural development is to systematically identify and learn from the ‘outliers’—places where ecosystems are substantially better (‘bright spots’) or worse (‘dark spots’) than expected, given the environmental conditions and socioeconomic drivers they are exposed to. Here we compile data from more than 2,500 reefs worldwide and develop a Bayesian hierarchical model to generate expectations of how standing stocks of reef fish biomass are related to 18 socioeconomic drivers and environmental conditions. We identify 15 bright spots and 35 dark spots among our global survey of coral reefs, defined as sites that have biomass levels more than two standard deviations from expectations. Importantly, bright spots are not simply comprised of remote areas with low fishing pressure; they include localities where human populations and use of ecosystem resources is high, potentially providing insights into how communities have successfully confronted strong drivers of change. Conversely, dark spots are not necessarily the sites with the lowest absolute biomass and even include some remote, uninhabited locations often considered near pristine. We surveyed local experts about social, institutional, and environmental conditions at these sites to reveal that bright spots are characterized by strong sociocultural institutions such as customary taboos and marine tenure, high levels of local engagement in management, high dependence on marine resources, and beneficial environmental conditions such as deep-water refuges. Alternatively, dark spots are characterized by intensive capture and storage technology and a recent history of environmental shocks. Our results suggest that investments in strengthening fisheries

  19. Bright spots among the world’s coral reefs.

    Science.gov (United States)

    Cinner, Joshua E; Huchery, Cindy; MacNeil, M Aaron; Graham, Nicholas A J; McClanahan, Tim R; Maina, Joseph; Maire, Eva; Kittinger, John N; Hicks, Christina C; Mora, Camilo; Allison, Edward H; D'Agata, Stephanie; Hoey, Andrew; Feary, David A; Crowder, Larry; Williams, Ivor D; Kulbicki, Michel; Vigliola, Laurent; Wantiez, Laurent; Edgar, Graham; Stuart-Smith, Rick D; Sandin, Stuart A; Green, Alison L; Hardt, Marah J; Beger, Maria; Friedlander, Alan; Campbell, Stuart J; Holmes, Katherine E; Wilson, Shaun K; Brokovich, Eran; Brooks, Andrew J; Cruz-Motta, Juan J; Booth, David J; Chabanet, Pascale; Gough, Charlie; Tupper, Mark; Ferse, Sebastian C A; Sumaila, U Rashid; Mouillot, David

    2016-07-21

    Ongoing declines in the structure and function of the world’s coral reefs require novel approaches to sustain these ecosystems and the millions of people who depend on them3. A presently unexplored approach that draws on theory and practice in human health and rural development is to systematically identify and learn from the ‘outliers’—places where ecosystems are substantially better (‘bright spots’) or worse (‘dark spots’) than expected, given the environmental conditions and socioeconomic drivers they are exposed to. Here we compile data from more than 2,500 reefs worldwide and develop a Bayesian hierarchical model to generate expectations of how standing stocks of reef fish biomass are related to 18 socioeconomic drivers and environmental conditions. We identify 15 bright spots and 35 dark spots among our global survey of coral reefs, defined as sites that have biomass levels more than two standard deviations from expectations. Importantly, bright spots are not simply comprised of remote areas with low fishing pressure; they include localities where human populations and use of ecosystem resources is high, potentially providing insights into how communities have successfully confronted strong drivers of change. Conversely, dark spots are not necessarily the sites with the lowest absolute biomass and even include some remote, uninhabited locations often considered near pristine6. We surveyed local experts about social, institutional, and environmental conditions at these sites to reveal that bright spots are characterized by strong sociocultural institutions such as customary taboos and marine tenure, high levels of local engagement in management, high dependence on marine resources, and beneficial environmental conditions such as deep-water refuges. Alternatively, dark spots are characterized by intensive capture and storage technology and a recent history of environmental shocks. Our results suggest that investments in strengthening fisheries

  20. Developing high brightness beams for heavy ion driven inertial fusion

    OpenAIRE

    Kwan, J.W.; Ahle, L.A.; Anders, A; Bieniosek, F.M.; Chacon-Golcher, E.; Grote, D. P.; Henestroza, E.; Leung, K.N.; Molvik, A.W.

    2001-01-01

    Heavy ion fusion (HIF) drivers require large currents and bright beams. In this paper we review the two different approaches for building HIF injectors and the corresponding ion source requirements. The traditional approach uses large aperture, low current density ion sources, resulting in a very large injector system. A more recent conceptual approach merges high current density mini-beamlets into a large current beam in order to significantly reduce the size of the injector. Experimen...

  1. Bright flares in supergiant fast X-ray transients

    Science.gov (United States)

    Shakura, N.; Postnov, K.; Sidoli, L.; Paizis, A.

    2014-08-01

    At steady low-luminosity states, supergiant fast X-ray transients (SFXTs) can be at the stage of quasi-spherical settling accretion on to slowly rotating magnetized neutron stars from the OB-companion winds. At this stage, a hot quasi-static shell is formed above the magnetosphere, the plasma entry rate into magnetosphere is controlled by (inefficient) radiative plasma cooling, and the accretion rate on to the neutron star is suppressed by a factor of ˜30 relative to the Bondi-Hoyle-Littleton value. Changes in the local wind velocity and density due to, e.g. clumps, can only slightly increase the mass accretion rate (a factor of ˜10) bringing the system into the Compton-cooling-dominated regime and led to the production of moderately bright flares (Lx ≲ 1036 erg s-1). To interpret the brightest flares (Lx > 1036 erg s-1) displayed by the SFXTs within the quasi-spherical settling accretion regimes, we propose that a larger increase in the mass accretion rate can be produced by sporadic capture of magnetized stellar wind plasma. At sufficiently low accretion rates, magnetic reconnection can enhance the magnetospheric plasma entry rate, resulting in copious production of X-ray photons, strong Compton cooling and ultimately in unstable accretion of the entire shell. A bright flare develops on the free-fall time-scale in the shell, and the typical energy released in an SFXT bright flare corresponds to the mass of the shell. This view is consistent with the energy released in SFXT bright flares (˜1038-1040 erg), their typical dynamic range (˜100) and with the observed dependence of these characteristics on the average unflaring X-ray luminosity of SFXTs. Thus, the flaring behaviour of SFXTs, as opposed to steady HMXBs, may be primarily related to their low X-ray luminosity allowing sporadic magnetic reconnection to occur during magnetized plasma entry into the magnetosphere.

  2. COLA. III. RADIO DETECTION OF ACTIVE GALACTIC NUCLEUS IN COMPACT MODERATE LUMINOSITY INFRARED GALAXIES

    International Nuclear Information System (INIS)

    We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median LIR = 1011.01 Lsun) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (∼1021 W Hz-1) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.

  3. Brightness limitations in multi-kiloampere electron beam sources

    International Nuclear Information System (INIS)

    Heuristic relationships such as the Lawson-Penner criterion, used to scale Free Electron Laser (FEL) amplifier gain and efficiency over orders of magnitude in beam current and brightness, have no fundamental basis. The brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. The design of low emittance, high current electron guns has received considerable attention at Livermore over the past few years. The measured brightnesses of the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA) guns are less than predicted with the EBQ gun design code; this discrepancy is due to plasma effects from the present cold, plasma cathode in the code. The EBQ code is well suited to exploring the current limits of gridless relativistic Pierce columns with moderate current density (2) at the cathode. As EBQ uses a steady-state calculation it is not amenable for study of transient phenomena at the beam head. For this purpose, a Darwin approximation code, DPC, has been written. The main component in our experimental cathode development effort is a readily modified electron gun that will allow us to test many candidate cathode materials, types and electrode geometries at field stresses up to 1 MV/cm. 6 references, 6 figures

  4. Night-sky brightness and extinction at Mt. Shatdzhatmaz

    CERN Document Server

    Kornilov, V; Voziakova, O; Shatsky, N; Safonov, B; Gorbunov, I; Potanin, S; Cheryasov, D; Senik, V

    2016-01-01

    The photometric sky quality of Mt. Shatdzhatmaz, the site of Sternberg Astronomical Institute Caucasian Observatory 2.5 m telescope, is characterized here by the statistics of the night-time sky brightness and extinction. The data were obtained as a by-product of atmospheric optical turbulence measurements with the MASS (Multi-Aperture Scintillation Sensor) device conducted in 2007--2013. The factors biasing night-sky brightness measurements are considered and a technique to reduce their impact on the statistics is proposed. The single-band photometric estimations provided by MASS are easy to transform to the standard photometric bands. The median moonless night-sky brightness is 22.1, 21.1, 20.3, and 19.0 mag per square arcsec for the $B$, $V$, $R$, and $I$ spectral bands, respectively. The median extinction coefficients for the same photometric bands are 0.28, 0.17, 0.13, and 0.09 mag. The best atmospheric transparency is observed in winter.

  5. Bright Soil Churned by Spirit's Sol 1861 Drive

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit drove 22.7 meters (74 feet) toward the southwest on the 1,861st Martian day, or sol, of Spirit's mission on Mars (March 28, 2009). After the drive, the rover took this image with its front hazard-avoidance camera, looking back at the tracks from the drive. As usual since losing the use of its right-front wheel in 2006, Spirit drove backwards. The immobile right-front wheel churned up a long stripe of bright soil during this drive. Where Spirit has found such bright soil in the past, subsequent analysis of the composition found concentrations of sulfur or silica that testified to past action of water at the site. When members of the rover team saw the large quantity of bright soil exposed by the Sol 1861 drive, they quickly laid plans to investigate the composition with Spirit's alpha particle X-ray spectrometer. The Sol 1861 drive took the rover past the northwest corner of the low plateau called 'Home Plate,' making progress on a route around the western side of Home Plate. The edge of Home Plate forms the horizon on the right side of this image. Husband Hill is on the horizon on the left side. For scale, the parallel rover wheel tracks are about 1 meter (40 inches) apart. The rover's hazard-avoidance cameras take 'fisheye' wide-angle images.

  6. HSV Brightness Factor Matching for Gesture Recognition System

    Directory of Open Access Journals (Sweden)

    Mokhtar M. Hasan

    2010-12-01

    Full Text Available The main goal of gesture recognition research is to establish a system which can identify specific human gestures and use these identified gestures to be carried out by the machine, In this paper, we introduce a new method for gesture recognition that based on computing the local brightness for each block of the gesture image, the gesture image is divided into 25x25 blocks each of 5x5 block size, and we calculated the local brightness of each block, so, each gesture produces 25x25 features value, our experimental shows that more that %60 of these features are zero value which leads to minimum storage space, this brightness value is calculated from the HSV (Hue, Saturation and Value color model that used for segmentation operation, the recognition rate achieved is %91 using 36 training gestures and 24 different testing gestures. This Paper focuses on the hand gesture instead of the whole body movement since hands are the most flexible part of the body and can transfer the most meaning, we build a gesture recognition system that can communicate with the machine in natural way without any mechanical devices and without using the normal input devices which are the keyboard and mouse and the mathematical equations will be the translator between the gestures and the telerobotic.

  7. Giant Low Surface Brightness Galaxies: Evolution in Isolation

    Indian Academy of Sciences (India)

    M. Das

    2013-03-01

    Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in surface brightness. They often have bright bulges that are similar to those found in early type galaxies. The bulges can host low luminosity Active Galactic Nuclei (AGN) that have relatively low mass black holes. GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies. In fact many GLSB galaxies are found under dense regions close to the edges of voids. These galaxies have very massive dark matter halos that also contribute to their stability and lack of evolution. In this paper we briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive dark matter halos have led to the low star formation rates and the slower rate of evolution in these galaxies.

  8. South African night sky brightness during high aerosol epochs

    CERN Document Server

    Winkler, Hartmut; Marang, Fred

    2014-01-01

    Sky conditions in the remote, dry north-western interior of South Africa are now the subject of considerable interest in view of the imminent construction of numerous solar power plants in this area. Furthermore, the part of this region in which the core of the SKA is to be located (which includes SALT) has been declared an Astronomical Advantage Zone, for which sky brightness monitoring will now be mandatory. In this project we seek to characterise the sky brightness profile under a variety of atmospheric conditions. Key factors are of course the lunar phase and altitude, but in addition the sky brightness is also significantly affected by the atmospheric aerosol loading, as that influences light beam scattering. In this paper we chose to investigate the sky characteristics soon after the Mount Pinatubo volcanic eruption in 1991, which resulted in huge ash masses reaching the stratosphere (where they affected solar irradiance for several years). We re-reduced photometric sky measurements from the South Afric...

  9. BRITE-Constellation: nanosatellites for precision photometry of bright stars

    CERN Document Server

    Weiss, W W; Moffat, A F J; Schwarzenberg-Czerny, A; Koudelka, O F; Grant, C C; Zee, R E; Kuschnig, R; Mochnacki, St; Matthews, J M; Orleanski, P; Pamyatnykh, A; Pigulski, A; Alves, J; Guedel, M; Handler, G; Wade, G A; Zwintz, K; CCD,

    2014-01-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, the brightness and temperature variations of stars generally brighter than mag(V) ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of six nanosats (hence Constellation): two from Austria, two from Canada, and two from Poland. Each 7 kg nanosat carries an optical telescope of aperture 3 cm feeding an uncooled CCD. One instrument in each pair is equipped with a blue filter, the other with a red filter. Each BRITE instrument has a wide field of view (~24 degrees), so up to about 15 bright stars can be observed simultaneously, sampled in 32 pixel x 32 pixel sub-rasters. Photometry of additional fainter targets, with reduced precision but thorough time sampling, will be possible through onboard data processing. The BRITE sample is dominated by the most intrinsically luminous stars: massive stars seen at all e...

  10. New insights into the photometric structure of Blue Compact Dwarf Galaxies from a deep Near-Infrared study

    CERN Document Server

    Noeske, K G; Cairos, L M; Fricke, K J

    2003-01-01

    We present deep Near-Infrared (NIR) imaging of Blue Compact Dwarf Galaxies (BCDs), allowing for the first time to derive and systematize the NIR structural properties of their stellar low-surface brightness (LSB) host galaxies. Compared to optical data, NIR images, being less contamined by the extended stellar and ionized gas emission from the starburst, permit to study the LSB host galaxy closer to its center. We find that radial surface brightness profiles (SBPs) of the LSB hosts show at large radii a mostly exponential intensity distribution, in agreement with previous optical studies. At small to intermediate radii, however, the NIR data reveal an inwards flattening with respect to the outer exponential slope ("type V SBPs", Binggeli & Cameron 1991) in the LSB component of more than one half of the sample BCDs. This result may constitute an important observational constraint to the dynamics and evolution of BCDs. We apply a modified exponential fitting function (Papaderos et al. 1996a) to parametrize ...

  11. Two-dimensional bright and dark-in-bright dipolar Bose–Einstein condensate solitons on a one-dimensional optical lattice

    Science.gov (United States)

    Adhikari, S. K.

    2016-08-01

    We study the statics and dynamics of anisotropic, stable, bright and dark-in-bright dipolar quasi-two-dimensional Bose–Einstein condensate (BEC) solitons on a one-dimensional (1D) optical-lattice (OL) potential. These solitons mobile in a plane perpendicular to a 1D OL trap can have both repulsive and attractive contact interactions. Dark-in-bright solitons are the excited states of bright solitons. The solitons, when subjected to a small perturbation, exhibit sustained breathing oscillation. Dark-in-bright solitons can be created by phase imprinting a bright soliton. At medium velocities the collision between two solitons is found to be quasi-elastic. Results are demonstrated by a numerical simulation of the three-dimensional mean-field Gross–Pitaevskii equation in three spatial dimensions employing realistic interaction parameters for a dipolar 164Dy BEC.

  12. Roller compaction of moist pharmaceutical powders.

    Science.gov (United States)

    Wu, C-Y; Hung, W-L; Miguélez-Morán, A M; Gururajan, B; Seville, J P K

    2010-05-31

    The compression behaviour of powders during roller compaction is dominated by a number of factors, such as process conditions (roll speed, roll gap, feeding mechanisms and feeding speed) and powder properties (particle size, shape, moisture content). The moisture content affects the powder properties, such as the flowability and cohesion, but it is not clear how the moisture content will influence the powder compression behaviour during roller compaction. In this study, the effect of moisture contents on roller compaction behaviour of microcrystalline cellulose (MCC, Avicel PH102) was investigated experimentally. MCC samples of different moisture contents were prepared by mixing as-received MCC powder with different amount of water that was sprayed onto the powder bed being agitated in a rotary mixer. The flowability of these samples were evaluated in terms of the poured angle of repose and flow functions. The moist powders were then compacted using the instrumented roller compactor developed at the University of Birmingham. The flow and compression behaviour during roller compaction and the properties of produced ribbons were examined. It has been found that, as the moisture content increases, the flowability of moist MCC powders decreases and the powder becomes more cohesive. As a consequence of non-uniform flow of powder into the compaction zone induced by the friction between powder and side cheek plates, all produced ribbons have a higher density in the middle and lower densities at the edges. For the ribbons made of powders with high moisture contents, different hydration states across the ribbon width were also identified from SEM images. Moreover, it was interesting to find that these ribbons were split into two halves. This is attributed to the reduction in the mechanical strength of moist powder compacts with high moisture contents produced at high compression pressures. PMID:20176096

  13. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans. : Phase delaying efficacy of intermittent bright light

    OpenAIRE

    Gronfier, Claude; Wright, Kenneth,; Kronauer, Richard,; Jewett, Megan,; Czeisler, Charles,

    2004-01-01

    International audience It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine whether a single sequence of brief bright light pulses administered ...

  14. Density-Driven Compactional Flow in Porous Media

    CERN Document Server

    Yang, Xin-She

    2010-01-01

    In the mathematical modelling of compactional flow in porous media, the constitutive relation is typically modelled in terms of a nonlinear relationship between effective pressure and porosity, and compaction is essentially poroelastic. However, at depths deeper than 1 km where pressure is high, compaction becomes more akin to a viscous one. Two mathematical models of compaction in porous media are formulated and the noninear equations are then solved numerically. The essential features of numerical profiles of poroelastic and viscous compaction are thus compared with asymptotic solutions. Two distinguished styles of density-driven compaction in fast and slow compacting sediments are analysed and shown in this paper.

  15. Collision induced splitting of bright soliton in Bose-Einstein condensate

    Institute of Scientific and Technical Information of China (English)

    Wang Yue-Yue; Zhang Jie-Fang

    2009-01-01

    This paper studies the collision dynamics of bright soliton in Bose-Einstein condensate with trapezoid potential. It is found that besides the total reflection and total transmission, one bright soliton can be divided into two bright solitons with different amplitudes in a controllable manner.

  16. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Superluminal Motion of Gamma-Ray Bright Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Wehrle, A E; Bloom, S D; Yurchenko, A V; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Wehrle, Ann E; Bloom, Steven D; Yurchenko, Alexei V

    2001-01-01

    We present the results of a program to monitor the structure of the radio emission in 42 $\\gamma$-ray bright blazars (31 quasars and 11 BL Lac objects) with the VLBA at 43, 22, and occasionally 15 and 8.4 GHz, over the period from November 1993 to July 1997. We determine proper motions in 33 sources and find that the apparent superluminal motions in $\\gamma$-ray sources are much faster than for the general population of bright compact radio sources. This follows the strong dependence of the $\\gamma$-ray flux on the level of relativistic beaming for both external-radiation Compton and synchrotron self-Compton emission. There is a positive correlation (correlation coefficient $r$=0.45) between the flux density of the VLBI core and the $\\gamma$-ray flux and a moderate correlation (partial correlation coefficient $r$=0.31) between $\\gamma$-ray apparent luminosity and superluminal velocities of jet components, as expected if the $\\gamma$-ray emission originates in a very compact region of the relativistic jet and ...

  17. Elve Doublets: The Ionospheric Fingerprints of Compact Intracloud Discharges

    Science.gov (United States)

    da Silva, C. L.; Marshall, R. A.; Pasko, V. P.

    2015-12-01

    Compact intracloud discharges (CIDs) persist to date as one of the most mysterious lightning manifestations. CIDs are known to be the strongest natural sources of radio-frequency radiation on Earth. At VHF frequencies, approximately above 30 MHz, their emitted power is ten times stronger than that of other lightning processes. The well-known strength of CIDs in VHF contrasts with the lack of substantial optical measurements. CID's VLF/LF electric field change waveforms resemble one full cycle of a distorted sine function, with the first half-cycle being (a few times) larger-amplitude and shorter-duration than the second. For this reason CIDs have been dubbed narrow bipolar events (NBEs). NBE waveshapes are strikingly similar to the largest initial breakdown pulses (IBPs) that occur during the earlier stages of a conventional lightning flash, called classic IBPs. The similarity between classic IBP and NBE far-field waveforms, combined with the fact that positive-polarity NBEs frequently appear as the first event in an otherwise regular positive intracloud discharge, may be indicative that the source of these two E-field pulse types share the same physical mechanism inside thunderclouds [da Silva and Pasko, JGR, 120, 4989-5009, 2015]. In this presentation, we introduce a novel way to investigate CIDs. We show evidence that CIDs can produce an unique ionospheric signature, named "elve doublets". These signatures are characterized by a pair of elves separated in time by 80-160 microseconds. Our analysis combines fast photometric elve data, equivalent-transmission-line models to describe the dynamics of CID source currents, and FDTD modeling of electromagnetic wave propagation in the Earth-ionosphere waveguide accounting for its nonlinear interaction with the lower ionosphere [Marshall et al., GRL, 42, 2015, doi:10.1002/2015GL064862]. We show that typical (negative-polarity) CID altitudes, between 14-22 km, explain the time delay observed in elve doublets, where the

  18. Design and development of compact readout electronics with silicon photomultiplier array for a compact imaging detector

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Hui; QI Yu-Jin; ZHAO Cui-Lan

    2012-01-01

    This work aims at developing compact readout electronics for a compact imaging detector module with silicon photomultiplier (SPM) array.The detector module consists of a LYSO crystal array coupling with a SensL's 4×4 SPM array.A compact multiplexed readout based on a discretized positioning circuit (DPC) was developed to reduce the readout channels from 16 to 4 outputs.Different LYSO crystal arrays of 4×4,8×8 and 12×12 with pixel sizes of 3.2,1.6 and 1.0 mm respectively,have been tested with the compact readout board using a 137Cs source.The initial results show that the compact imaging detector module with the compact multiplexed readout could clearly resolve 1 mm×1 mm×10 mm LYSO scintillation crystal array except those at the edges.The detector's intrinsic spatial resolution up to 1 mm can be achieved with the 3 mm×3 mm size SPMArray4 through light sharing and compact multiplexed readout.Our results indicate that this detector module is feasible for the development of high-resolution compact PET.

  19. Aligning laboratory and field compaction practices for asphalt - the influence of compaction temperature on mechanical properties

    NARCIS (Netherlands)

    Bijleveld, F.R.; Miller, S.R.; Bondt, de A.H.; Doree, A.G.

    2015-01-01

    The approach used to identify a compaction temperature in the laboratory, based on binder viscosity, provides a single compaction temperature whereas, on-site, a roller operates within a temperature window. The effect on the density and mechanical properties of rolling during a temperature window re

  20. COMPACT PROTON INJECTOR AND FIRST ACCELERATOR SYSTEM TEST FOR COMPACT PROTON DIELECTRIC WALL CANCER THERAPY ACCELERATOR

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y; Guethlein, G; Caporaso, G; Sampayan, S; Blackfield, D; Cook, E; Falabella, S; Harris, J; Hawkins, S; Nelson, S; Poole, B; Richardson, R; Watson, J; Weir, J; Pearson, D

    2009-04-23

    A compact proton accelerator for cancer treatment is being developed by using the high-gradient dielectric insulator wall (DWA) technology [1-4]. We are testing all the essential DWA components, including a compact proton source, on the First Article System Test (FAST). The configuration and progress on the injector and FAST will be presented.