WorldWideScience

Sample records for central compact objects

  1. Evidence for a binary origin of a central compact object

    CERN Document Server

    Doroshenko, Victor; Kavanagh, Patrick; Santangelo, Andrea; Suleimanov, Valery; Klochkov, Dmitry

    2015-01-01

    Central compact objects are thought to be young thermally emitting isolated neutron stars that were born during the preceding core-collapse supernova explosion. Here we present the first evidence that at least in one case the neutron star must have formed within a binary system. The former stellar companion, surrounded by a dust shell with an estimated mass of $\\sim0.4-1.5M_\\odot$ , is going through the final stages of its own evolution as a post-asymptotic giant branch star. We argue that accretion of matter supplied by the companion soon after the supernova explosion is likely responsible for dampening of the magnetic field of the central compact object to its presently low value.

  2. Evidence for a binary origin of a central compact object

    Science.gov (United States)

    Doroshenko, Victor; Pühlhofer, Gerd; Kavanagh, Patrick; Santangelo, Andrea; Suleimanov, Valery; Klochkov, Dmitry

    2016-05-01

    Central compact objects (CCOs) are thought to be young thermally emitting isolated neutron stars that were born during the preceding core-collapse supernova explosion. Here, we present evidence that at least in one case the CCO could have been formed within a binary system. We show that the highly reddened optical source IRAS 17287-3443, located 25 arcsec away from the CCO candidate XMMUJ173203.3-344518 and classified previously as a post asymptotic giant branch star, is indeed surrounded by a dust shell. This shell is heated by the central star to temperatures of ˜90 K and observed as extended infrared emission in 8-160 μm band. The dust temperature also increases in the vicinity of the CCO which implies that it likely resides within the shell. We estimate the total dust mass to be ˜0.4-1.5 M⊙ which significantly exceeds expected dust yields by normal stars and thus likely condensed from supernova ejecta. Taking into account that both the age of the supernova remnant and the duration of active mass-loss phase by the optical star are much shorter than the total lifetime of either object, the supernova and the onset of the active mass-loss phase of the companion have likely occurred approximately simultaneously. This is most easily explained if the evolution of both objects is interconnected. We conclude, therefore, that both stars were likely members of the same binary system disrupted by a supernova.

  3. Hunting for Orphaned Central Compact Objects among Radio Pulsars

    CERN Document Server

    Luo, J; Ho, W C G; Bogdanov, S; Kaspi, V M; He, C

    2015-01-01

    Central compact objects (CCOs) are a handful of young neutron stars found at the center of supernova remnants (SNRs). They show high thermal X-ray luminosities but no radio emission. Spin-down rate measurements of the three CCOs with X-ray pulsations indicate surface dipole fields much weaker than those of typical young pulsars. To investigate if CCOs and known radio pulsars are objects at different evolutionary stages, we carried out a census of all weak-field (<1e11 G) isolated radio pulsars in the Galactic plane to search for CCO-like X-ray emission. None of the 12 candidates is detected at X-ray energies, with luminosity limits of 1e32-1e34 erg/s. We consider a scenario in which the weak surface fields of CCOs are due to rapid accretion of supernova materials and show that as the buried field diffuses back to the surface, a CCO descendant is expected to leave the P-Pdot parameter space of our candidates at a young age of a few times 10kyr. Hence, the candidates are likely to be just old ordinary pulsar...

  4. 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...

  5. A Central Compact Object in Kes 79: The hypercritical regime and neutrino expectation

    CERN Document Server

    Bernal, Cristian G

    2016-01-01

    We present magnetohydrodynamical simulations of a strong accretion onto magnetized proto-neutron stars for the Kesteven 79 (Kes 79) scenario. The supernova remnant Kes 79, observed with the Chandra ACIS-I instrument during approximately 8.3 h, is located in the constellation Aquila at a distance of 7.1 kpc in the galactic plane. It is a galactic and a very young object with an estimate age of 6 kyr. The Chandra image has revealed, for the first time, a point-like source at the center of the remnant. The Kes 79 compact remnant belongs to a special class of objects, the so-called Central Compact Objects, which exhibits no evidence for a surrounding pulsar wind nebula. In this work we show that the submergence of the magnetic field during the hypercritical phase can explain such behavior for Kes 79 and others CCOs. The simulations of such regime were carried out with the adaptive-mesh-refinement code FLASH in two spatial dimensions, including radiative loss by neutrinos and an adequate equation of state for such...

  6. Magnetar-like activity from the central compact object in the SNR RCW103

    CERN Document Server

    Rea, Nanda; Esposito, Paolo; Zelati, Francesco Coti; Bachetti, Matteo; Israel, Gianluca; De Luca, Andrea

    2016-01-01

    The 6.67 hr long periodicity and the variable X-ray flux, of the central compact object (CCO) at the center of the SNR RCW 103, named 1E 161348-5055, have been always difficult to interpret within the standard scenarios of an isolated neutron star or a binary system. On 2016 June 22, the Burst Alert Telescope (BAT) onboard Swift detected a magnetar-like short X-ray burst from the direction of 1E 161348-5055, also coincident with a large long-term X-ray outburst. Here we report on the properties of this magnetar-like burst, on the Chandra, NuSTAR, and Swift (BAT and XRT) observations of this peculiar source during its 2016 outburst peak, as well as on the study of its long-term X-ray outburst activity (from 1999 to July 2016). We find that all the X-ray properties of this object are perfectly in line with it being a magnetar, which undergoes typical X-ray flares and transient events. However, in this scenario, the 6.67 hr periodicity can only be interpreted as the rotation period of this strongly magnetized ne...

  7. 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.

  8. A dedicated Chandra ACIS observation of the central compact object in the Cassiopeia A supernova remnant

    CERN Document Server

    Pavlov, G G

    2009-01-01

    We present results of a recent Chandra X-ray Observatory observation of the central compact object (CCO) in the supernova remnant Cassiopeia A. This observation was obtained in an instrumental configuration that combines a high spatial resolution with a minimum spectral distortion, and it allowed us to search for pulsations with periods longer than 0.68 s. We found no evidence of extended emission associated with the CCO, nor statistically significant pulsations (an upper limit on pulsed fraction is about 10%). The fits of the CCO spectrum with the power-law model yield a large photon index, Gamma\\approx 5, and a hydrogen column density larger than that obtained from the SNR spectra. The fits with the blackbody model are statistically unacceptable. Better fits are provided by hydrogen or helium neutron star atmosphere models, with the best-fit effective temperature kT_{eff}^\\infty \\approx 0.2 keV, but they require a small star's radius, R = 4 - 5.5 km, and a low mass, M < 0.8 M_sol. A neutron star cannot h...

  9. X-RAY OBSERVATIONS OF DISRUPTED RECYCLED PULSARS: NO REFUGE FOR ORPHANED CENTRAL COMPACT OBJECTS

    International Nuclear Information System (INIS)

    We present a Chandra X-ray survey of the disrupted recycled pulsars (DRPs), isolated radio pulsars with P > 20 ms and Bs 10 G. These observations were motivated as a search for the immediate descendants of the ≈10 central compact objects (CCOs) in supernova remnants (SNRs), 3 of which have similar timing and magnetic properties as the DRPs, but are bright, thermal X-ray sources consistent with minimal neutron star (NS) cooling curves. Since none of the DPRs were detected in this survey, there is no evidence that they are ''orphaned'' CCOs, NSs whose SNRs has dissipated. Upper limits on their thermal X-ray luminosities are in the range of log Lx [erg s–1] = 31.8-32.8, which implies cooling ages >104-105 yr, roughly 10 times the ages of the ≈10 known CCOs in a similar volume of the Galaxy. The order of a hundred CCO descendants that could be detected by this method are thus either intrinsically radio quiet or occupy a different region of (P, Bs ) parameter space from the DRPs. This motivates a new X-ray search for orphaned CCOs among radio pulsars with larger B-fields, which could verify the theory that their fields are buried by the fall-back of supernova ejecta, but quickly regrow to join the normal pulsar population

  10. New constraints on the cooling of the Central Compact Object in Cas A

    CERN Document Server

    Posselt, B; Suleimanov, V; Kargaltsev, O

    2013-01-01

    To examine the previously claimed fast cooling of the Central Compact Object (CCO) in the Cas A supernova remnant (SNR), we analyzed two Chandra observations of this CCO, taken in a setup minimizing instrumental spectral distortions. We fit the two CCO X-ray spectra from 2006 and 2012 with hydrogen and carbon neutron star atmosphere models. The temperature and flux changes in the 5.5 years between the two epochs depend on the adopted constraints on the fitting parameters and the uncertainties of the effective area calibrations. If we allow a change of the equivalent emitting region size, R_Em, the effective temperature remains essentially the same. If R_Em is held constant, the best-fit temperature change is negative, but its statistical significance ranges from 0.8sigma to 2.5sigma, depending on the model. If we assume that the optical depth of the ACIS filter contaminant in 2012 was +/-10% different from its default calibration value, the significance of the temperature drop becomes 0.8sigma to 3.1sigma, fo...

  11. New constraints on the cooling of the central compact object in CAS A

    Energy Technology Data Exchange (ETDEWEB)

    Posselt, B.; Pavlov, G. G. [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Suleimanov, V. [Institut für Astronomie und Astrophysik Tübingen, Sand 1, D-72076 Tübingen (Germany); Kargaltsev, O., E-mail: posselt@psu.edu [Department of Physics, The George Washington University, Washington, DC 20052 (United States)

    2013-12-20

    To examine the previously claimed fast cooling of the Central Compact Object (CCO) in the Cas A supernova remnant (SNR), we analyzed two Chandra observations of this CCO, taken in a setup minimizing instrumental spectral distortions. We fit the two CCO X-ray spectra from 2006 and 2012 with hydrogen and carbon neutron star atmosphere models. The temperature and flux changes in the 5.5 yr between the two epochs depend on the adopted constraints on the fitting parameters and the uncertainties of the effective area calibrations. If we allow a change of the equivalent emitting region size, R {sub Em}, the effective temperature remains essentially the same. If R {sub Em} is held constant, the best-fit temperature change is negative, but its statistical significance ranges from 0.8σ to 2.5σ, depending on the model. If we assume that the optical depth of the ACIS filter contaminant in 2012 was ±10% different from its default calibration value, the significance of the temperature drop becomes 0.8σ-3.1σ, for the carbon atmospheres with constant R {sub Em}. Thus, we do not see a statistically significant temperature drop in our data, but the involved uncertainties are too large to firmly exclude the previously reported fast cooling. Our analysis indicate a decrease of 4%-6% (1.9σ-2.9σ significance) for the absorbed flux in the energy range 0.6-6 keV between 2006 and 2012, most prominent in the ≈1.4-1.8 keV energy range. It could be caused by unaccounted changes of the detector response or contributions from unresolved SNR material along the line of sight to the CCO.

  12. Compact cosmic objects

    International Nuclear Information System (INIS)

    The data are discussed obtained using the method of superfar radiointerferometry. High angular resolution of radiointerferometers with superlong bases has made compact radiosources placed inside and beyond the Galaxy accessable for investigations. Outer galactic objects with extraordinarily active nuclei have been found. Seyfert galaxies 3C84(NGC 1275) in the Perseus constellation and 3C 345 quasar in the Hercules constellation are objects with active nuclei. In the nuclei of separate quasars extraordinarily active processes take place which are accompanied by outflow of clouds of relativistic particles. The velocity of these particles exceeds the light velocity. Measurements with high angular resolution performed in the shortest wave of the centimeter range (1.35 cm) have permitted to find the double nucleus in the Seyfert galaxy NGC 1275. The superfar radiointerferometry has made interesting discoveries when studying gas-dust galactic nebular. Laser sources that emit bright and narrow lines of hydroxyl and water vapour are found in them

  13. Globular cluster winds with central accretion by a massive compact object or subcluster

    International Nuclear Information System (INIS)

    Steady-state isothermal wind flows with accretion by a central mass concentration in spherically symmetric systems of gas-losing stars are computed. Solutions are uniquely determined by two dimensionless parameters lambda and m, where lambda approximately (central escape velocity/sound speed)2 and m approximately (central point mass/cluster core mass). The models are applied to globular clusters for two types of central mass concentration - a single massive black hole and a subcluster of massive stars. A hard (> keV) X-ray source due to a central black hole fed by clusterwide inflow does not provide a consistent model for globular cluster X-ray sources. However, in the case of hot (T approximately > 2 x 105 K) winds, gas trapping by a central subcluster of neutron stars or of binaries containing white dwarfs could explain recent UV and Hα observations. Similar applications to elliptical galaxies are discussed. (author)

  14. Globular cluster winds with central accretion by a massive compact object or subcluster

    Science.gov (United States)

    Durisen, R. H.; Burns, J. O.

    1981-01-01

    Steady-state isothermal wind flows are computed with accretion by a central mass concentration in spherically symmetric systems of gas-losing stars. Solutions are uniquely determined by two dimensionless parameters lambda and m, where lambda is approximately equal to the square of the ratio of the central escape velocity to the sound speed and m is approximately equal to the ratio of the central point mass to the cluster core mass. The models are applied to globular clusters for two types of central mass concentration - a single massive black hole and a subcluster of massive stars. A hard (greater than a keV) X-ray source due to a central black hole fed by clusterwide inflow does not provide a consistent model for globular cluster X-ray sources. However, in the case of hot (T being greater than or approximately equal to 2 x 10 to the 5th K) winds, gas trapping by a central subcluster of neutron stars or of binaries containing white dwarfs could explain recent UV and H-alpha observations. Similar applications to elliptical galaxies are discussed.

  15. Central compact objects, superslow X-ray pulsars, gamma-ray bursts: do they have anything to do with magnetars?

    CERN Document Server

    Tong, H

    2014-01-01

    Magnetars and many of the magnetar-related objects are summarized together and discussed. It is shown that there is an abuse of language in the use of "magnetar". Anomalous X-ray pulsars and soft gamma-ray repeaters are well-known magnetar candidates. The current so called anti-magnetar (for central compact objects), accreting magnetar (for superslow X-ray pulsars in high mass X-ray binaries), and millisecond magnetar (for the central engine of some gamma-ray bursts), they may not be real magnetars in present understandings. Their observational behaviors are not caused by the magnetic energy. Many of them are just neutron stars with strong surface dipole field. A neutron star plus strong dipole field is not a magnetar. The characteristic parameters of the neutron stars for the central engine of some gamma-ray bursts are atypical from the neutron stars in the Galaxy. Possible signature of magnetic activities in accreting systems are discussed, including repeated bursts and a hard X-ray tail. China's future har...

  16. Study of a new central compact object: The neutron star in the supernova remnant G15.9+0.2

    CERN Document Server

    Klochkov, D; Sasaki, M; Santangelo, A

    2016-01-01

    We present our study of the central point source CXOU J181852.0-150213 in the young Galactic supernova remnant (SNR) G15.9+0.2 based on the recent ~90 ks Chandra observations. The point source was discovered in 2005 in shorter Chandra observations and was hypothesized to be a neutron star associated with the SNR. Our X-ray spectral analysis strongly supports the hypothesis of a thermally emitting neutron star associated with G15.9+0.2. We conclude that the object belongs to the class of young cooling low-magnetized neutron stars referred to as central compact objects (CCOs). We modeled the spectrum of the neutron star with a blackbody spectral function and with our hydrogen and carbon neutron star atmosphere models, assuming that the radiation is uniformly emitted by the entire stellar surface. Under this assumption, only the carbon atmosphere models yield a distance that is compatible with a source located in the Galaxy. In this respect, CXOU J181852.0-150213 is similar to two other well-studied CCOs, the ne...

  17. CONSTRAINING THE EVOLUTIONARY FATE OF CENTRAL COMPACT OBJECTS: ''OLD'' RADIO PULSARS IN SUPERNOVA REMNANTS

    International Nuclear Information System (INIS)

    Central compact objects (CCOs) constitute a population of radio-quiet, slowly spinning (≥100 ms) young neutron stars with anomalously high thermal X-ray luminosities. Their spin-down properties imply weak dipole magnetic fields (∼1010-11 G) and characteristic ages much greater than the ages of their host supernova remnants (SNRs). However, CCOs may posses strong ''hidden'' internal magnetic fields that may re-emerge on timescales of ≳10 kyr, with the neutron star possibly activating as a radio pulsar in the process. This suggests that the immediate descendants of CCOs may be masquerading as slowly spinning ''old'' radio pulsars. We present an X-ray survey of all ordinary radio pulsars within 6 kpc that are positionally coincident with Galactic SNRs in order to test the possible connection between the supposedly old but possibly very young pulsars and the SNRs. None of the targets exhibit anomalously high thermal X-ray luminosities, suggesting that they are genuine old ordinary pulsars unrelated to the superposed SNRs. This implies that CCOs are either latent radio pulsars that activate long after their SNRs dissipate or they remain permanently radio-quiet. The true descendants of CCOs remain at large

  18. 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.

  19. Compact objects in Horndeski gravity

    CERN Document Server

    Silva, Hector O; Minamitsuji, Masato; Berti, Emanuele

    2016-01-01

    Horndeski gravity holds a special position as the most general extension of Einstein's theory of general relativity 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 general relativity in cosmology and astrophysics. We present a review of the progress made so far in the study of compact objects (black holes and neutron stars) within Horndeski gravity. In particular, we review our recent work on slowly rotating black holes and present some new results on slowly rotating neutron stars.

  20. 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.

  1. 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.

  2. Binding Energy and Equilibrium of Compact Objects

    Directory of Open Access Journals (Sweden)

    Germano M.

    2014-04-01

    Full Text Available The theoretical analysis of the existence of a limit mass for compact astronomic ob- jects requires the solution of the Einstein’s equations of g eneral relativity together with an appropriate equation of state. Analytical solutions exi st in some special cases like the spherically symmetric static object without energy sou rces that is here considered. Solutions, i.e. the spacetime metrics, can have a singular m athematical form (the so called Schwarzschild metric due to Hilbert or a nonsingula r form (original work of Schwarzschild. The former predicts a limit mass and, conse quently, the existence of black holes above this limit. Here it is shown that, the origi nal Schwarzschild met- ric permits compact objects, without mass limit, having rea sonable values for central density and pressure. The lack of a limit mass is also demonst rated analytically just imposing reasonable conditions on the energy-matter densi ty, of positivity and decreas- ing with radius. Finally the ratio between proper mass and to tal mass tends to 2 for high values of mass so that the binding energy reaches the lim it m (total mass seen by a distant observer. As it is known the negative binding energ y reduces the gravitational mass of the object; the limit of m for the binding energy provides a mechanism for stable equilibrium of any amount of mass to contrast the gravitatio nal collapse.

  3. 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...

  4. 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.

  5. Accretion Disk Outflows from Compact Object Mergers

    Science.gov (United States)

    Metzger, Brian

    Nuclear reactions play a key role in the accretion disks and outflows associated with the merger of binary compact objects and the central engines of gamma-ray bursts and supernovae. The proposed research program will investigate the impact of nucleosynthesis on these events and their observable signatures by means of analytic calculations and numerical simulations. One focus of this research is rapid accretion following the tidal disruption of a white dwarf (WD) by a neutron star (NS) or black hole (BH) binary companion. Tidal disruption shreds the WD into a massive torus composed of C, O, and/or He, which undergoes nuclear reactions and burns to increasingly heavier elements as it flows to smaller radii towards the central compact object. The nuclear energy so released is comparable to that released gravitationally, suggesting that burning could drastically alter the structure and stability of the accretion flow. Axisymmetric hydrodynamic simulations of the evolution of the torus including nuclear burning will be performed to explore issues such as the mass budget of the flow (accretion vs. outflows) and its thermal stability (steady burning and accretion vs. runaway explosion). The mass, velocity, and composition of outflows from the disk will be used in separate radiative transfer calculations to predict the lightcurves and spectra of the 56Ni-decay powered optical transients from WD-NS/WD-BH mergers. The possible connection of such events to recently discovered classes of sub-luminous Type I supernovae will be assessed. The coalescence of NS-NS/NS-BH binaries also results in the formation of a massive torus surrounding a central compact object. Three-dimensional magnetohydrodynamic simulations of the long-term evolution of such accretion disks will be performed, which for the first time follow the effects of weak interactions and the nuclear energy released by Helium recombination. The nucleosynthetic yield of disk outflows will be calculated using a detailed

  6. Tidal deformations of a spinning compact object

    CERN Document Server

    Pani, Paolo; Maselli, Andrea; Ferrari, Valeria

    2015-01-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the multipole mom...

  7. Numerical simulations of compact object binaries

    OpenAIRE

    Pfeiffer, Harald P.

    2012-01-01

    Coalescing compact object binaries consisting of black holes and/or Neutron stars are a prime target for ground-based gravitational wave detectors. This article reviews the status of numerical simulations of these systems, with an emphasis on recent progress.

  8. Tidal deformations of a spinning compact object

    Science.gov (United States)

    Pani, Paolo; Gualtieri, Leonardo; Maselli, Andrea; Ferrari, Valeria

    2015-07-01

    The deformability of a compact object induced by a perturbing tidal field is encoded in the tidal Love numbers, which depend sensibly on the object's internal structure. These numbers are known only for static, spherically-symmetric objects. As a first step to compute the tidal Love numbers of a spinning compact star, here we extend powerful perturbative techniques to compute the exterior geometry of a spinning object distorted by an axisymmetric tidal field to second order in the angular momentum. The spin of the object introduces couplings between electric and magnetic deformations and new classes of induced Love numbers emerge. For example, a spinning object immersed in a quadrupolar, electric tidal field can acquire some induced mass, spin, quadrupole, octupole and hexadecapole moments to second order in the spin. The deformations are encoded in a set of inhomogeneous differential equations which, remarkably, can be solved analytically in vacuum. We discuss certain subtleties in defining the tidal Love numbers in general relativity, which are due to the difficulty in separating the tidal field from the linear response of the object in the solution, even in the static case. By extending the standard procedure to identify the linear response in the static case, we prove analytically that the Love numbers of a Kerr black hole remain zero to second order in the spin. As a by-product, we provide the explicit form for a slowly-rotating, tidally-deformed Kerr black hole to quadratic order in the spin, and discuss its geodesic and geometrical properties.

  9. Compact stellar object: the formation and structure

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, S.B. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

    2012-07-01

    Full text: The formation of compact objects is viewed at the final stages of stellar evolution. The supernova explosion events are then focalized to explain the formation of pulsars, hybrid neutron star and the limit case of the latter, the quark stars. We discuss the stability and structure of these objects in connection with the properties of the hadron and quark-gluon plasma equation of state. The hadron-quark phase transition in deep interior of these objects is discussed taking into account the implications on the density distribution of matter along the radial direction. The role of neutrinos confinement in the ultradense stellar medium in the early stages of pulsar formation is another interesting aspect to be mentioned in this presentation. Recent results for maximum mass of compact stellar objects for different forms of equations of state will be shown, presenting some theoretical predictions for maximum mass of neutron stars allowed by different equations of state assigned to dense stellar medium. Although a density greater than few times the nuclear equilibrium density appears in deep interior of the core, at the crust the density decreases by several orders of magnitude where a variety of hadronic states appears, the 'pasta'-states of hadrons. More externally, a lattice of nuclei can be formed permeated not only by electrons but also by a large amount of free neutrons and protons. These are possible structure of neutron star crust to have the density and pressures with null values at the neutron star surface. The ultimate goal of this talk is to give a short view of the compact star area for students and those who are introducing in this subject. (author)

  10. Double compact objects. II. Cosmological merger rates

    Energy Technology Data Exchange (ETDEWEB)

    Dominik, Michal; Belczynski, Krzysztof; Bulik, Tomasz [Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); Fryer, Christopher [CCS-2, MSD409, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Holz, Daniel E. [Enrico Fermi Institute, Department of Physics, and Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Berti, Emanuele [Department of Physics and Astronomy, The University of Mississippi, University, MS 38677 (United States); Mandel, Ilya [School of Physics and Astronomy, University of Birmingham, Edgbaston, B15 2TT (United Kingdom); O' Shaughnessy, Richard [University of Wisconsin-Milwaukee, 462 Physics Building, 1900 East Kenwood Boulevard, Milwaukee, WI 53217 (United States)

    2013-12-10

    The development of advanced gravitational wave (GW) observatories, such as Advanced LIGO and Advanced Virgo, provides impetus to refine theoretical predictions for what these instruments might detect. In particular, with the range increasing by an order of magnitude, the search for GW sources is extending beyond the 'local' universe and out to cosmological distances. Double compact objects (neutron star-neutron star (NS-NS), black hole-neutron star (BH-NS), and black hole-black hole (BH-BH) systems) are considered to be the most promising GW sources. In addition, NS-NS and/or BH-NS systems are thought to be the progenitors of gamma-ray bursts and may also be associated with kilonovae. In this paper, we present the merger event rates of these objects as a function of cosmological redshift. We provide the results for four cases, each one investigating a different important evolution parameter of binary stars. Each case is also presented for two metallicity evolution scenarios. We find that (1) in most cases NS-NS systems dominate the merger rates in the local universe, while BH-BH mergers dominate at high redshift, (2) BH-NS mergers are less frequent than other sources per unit volume, for all time, and (3) natal kicks may alter the observable properties of populations in a significant way, allowing the underlying models of binary evolution and compact object formation to be easily distinguished. This is the second paper in a series of three. The third paper will focus on calculating the detection rates of mergers by GW telescopes.

  11. Compact objects in pure Lovelock theory

    CERN Document Server

    Dadhich, Naresh; Chilambwe, Brian

    2016-01-01

    For static fluid interiors of compact objects in pure Lovelock gravity (involving ony one $N$th order term in the equation) we establish similarity in solutions for the critical odd and even $d=2N+1, 2N+2$ dimensions. It turns out that in critical odd $d=2N+1$ dimensions, there can exist no bound distribution with a finite radius, while in critical even $d=2N+2$ dimensions, all solutions have similar behavior. For exhibition of similarity we would compare star solutions for $N =1, 2$ in $d=4$ Einstein and $d=6$ in Gauss-Bonnet theory respectively. We also obtain the pure Lovelock analogue of the Finch-Skea model.

  12. Difficulties for Compact Composite Object Dark Matter

    CERN Document Server

    Cumberbatch, D T; Starkman, G D; Cumberbatch, Daniel T.; Silk, Joseph; Starkman, Glenn D.

    2006-01-01

    Recently Zhitnitsky suggested ``that DM particles are strongly interacting composite macroscopically large objects ... made of well known light quarks (or >... antiquarks)." In doing so he argued that these compact composite objects (CCOs) are ``natural explanations of many observed data, such as [the] 511 keV line from the bulge of our galaxy" and the CHANDRA-observed excess of diffuse X-ray emission toward the galactic center. Here we argue that the annihilation of interstellar electrons (or positrons) off positrons (or electrons) in the the CCO does not lead to the observed narrow 511 keV line, but to a broad continuum due to the high densities of the CCO-confined leptons. We argue further that in order to generate the observed flux of X-rays, the CCOs in the galactic centre would only require a temperature of 1 eV, and therefore unlikely to be the dominant heat source for the surrounding 8 keV plasma. While these observations do not rule out CCOs as galactic dark matter, they do weaken the motivation for ...

  13. 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

  14. Neutron stars: compact objects with relativistic gravity

    CERN Document Server

    Ekşi, K Yavuz

    2015-01-01

    General properties of neutron stars are briefly reviewed with an emphasis on the indispensability of general relativity in our understanding of these fascinating objects. In Newtonian gravity the pressure within a star merely plays the role of opposing self-gravity. In general relativity all sources of energy and momentum contribute to the gravity. As a result the pressure not only opposes gravity but also enhances it. The later role of pressure becomes more pronounced with increasing compactness, $M/R$ where $M$ and $R$ are the mass and radius of the star, and sets a critical mass beyond which collapse is inevitable. This critical mass has no Newtonian analogue; it is conceptually different than the Stoner-Landau-Chandrasekhar limit in Newtonian gravity which is attained asymptotically for ultra-relativistic fermions. For white dwarfs the general relativistic critical mass is very close to the Stoner-Landau-Chandrasekhar limit. For neutron stars the maximum mass---so called Oppenheimer-Volkoff limit---is sig...

  15. 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.

  16. Binary compact object inspiral: Detection expectations

    Indian Academy of Sciences (India)

    Vassiliki Kalogera

    2004-10-01

    We review the current estimates of binary compact object inspiral rates in particular in view of the recently discovered highly relativistic binary pulsar J0737-3039. One of the robust results is that, because of this discovery, the rate estimates for binary neutron stars have increased by a factor of 6-7 independent of any uncertainties related to the pulsar population properties. This rate increase has dramatic implications for gravitational wave detectors. For initial LIGO, the most probable detection rates for double neutron star (DNS) inspirals is 1 event/(5{250) yr; at 95% confidence we obtain rates up to 1/1.5 yr. For advanced LIGO, the most probable rates are 20-1000 events/yr. These predictions, for the first time, bring the expectations for DNS detections by initial LIGO to the astrophysically relevant regime. We also use our models to predict that the large-scale Parkes multibeam pulsar survey with acceleration searches could detect an average of three to four binary pulsars similar to those known at present. In comparison, rate estimates for binaries with black holes are derived based on binary evolution calculation, and based on the optimistic ends of the ranges, remain an important candidate for inspiral detection in the next few years. We also consider another aspect of the detectability of binary inspiral: the effect of precession on the detection efficiency of astrophysically relevant binaries. Based on our current astrophysical expectations, large tilt angles are not favored. As a result the decrease in detection rate varies rather slowly with black hole spin magnitude and is within 20-30% of the maximum possible values.

  17. Cold dark matter as compact composite objects

    Science.gov (United States)

    Zhitnitsky, Ariel

    2006-08-01

    Dark matter (DM) being the vital ingredient in the cosmos, still remains a mystery. The standard assumption is that the collisionless cold dark matter (CCDM) particles are represented by some weakly interacting fundamental fields which cannot be associated with any standard quarks or leptons. However, recent analyses of structure on galactic and subgalactic scales have suggested discrepancies and stimulated numerous alternative proposals including, e.g. self-interacting dark matter, self-annihilating dark matter, decaying dark matter, to name just a few. We propose the alternative to the standard assumption about the nature of DM particles (which are typically assumed to be weakly interacting fundamental pointlike particles, yet to be discovered). Our proposal is based on the idea that DM particles are strongly interacting composite macroscopically large objects which made of well-known light quarks (or even antiquarks). The required weakness of the DM particle interactions is guaranteed by a small geometrical factor γ˜(area)/(volume)˜B-1/3≪1 of the composite objects with a large baryon charge B≫1, rather than by a weak coupling constant of a new field. We argue that the interaction between hadronic matter and composite dark objects does not spoil the desired properties of the latter as cold matter. We also argue that such a scenario does not contradict to the current observational data. Rather, it has natural explanations of many observed data, such as ΩDM/ΩB˜1 or 511 KeV line from the bulge of our galaxy. We also suggest that composite dark matter may modify the dynamics of structure formation in the central overdense regions of galaxies. We also present a number of other cosmological/astrophysical observations which indirectly support the novel concept of DM nature.

  18. Hans A. Bethe Prize: Mergers of Binary Compact Objects

    Science.gov (United States)

    Kalogera, Vassiliki

    2016-03-01

    The inspiral and eventual merger of two compact objects in binary systems are important in astrophysics across the electromagnetic spectrum and as potential gravitational-wave sources. In this talk I will select a few topics of current interest to highlight compact-object mergers, including in the context of multi-messenger astrophysics.

  19. Measured compaction for 24 extensometers in the Central Valley

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset contains the compaction data for 24 extensometers used for observations in the Central Valley Hydrologic Model (CVHM). The Central Valley...

  20. High Energy Gamma Rays from Protons Hitting Compact Objects

    CERN Document Server

    Barbieri, J

    2008-01-01

    In a previous paper the spectrum of positrons produced by matter initially at rest falling onto a massive compact object was calculated. In this paper this calculation is generalized to obtain both the spectrum of in-flight positron annihilation and pi0 decay gamma rays produced when protons with a cosmic ray-like spectrum hit the surface. The resulting pi0 decay gamma ray spectrum reflects the high energy proton energy spectrum, and is largely independent of the mass of the compact object. One notable prediction for all compact objects is a dip in the spectrum below 70 MeV. As applied to the 10^6 solar mass massive compact object near to the center of our galaxy, our theory shows promise for explaining the gamma rays coming from the galactic center as observed by both the Compton satellite and HESS ground based array.

  1. Ondas gravitacionales y objetos compactos (Gravitational waves and compact objects)

    CERN Document Server

    de Araujo, J C N

    2013-01-01

    It is presented a brief review on gravitational waves (GWs). It is shown how the wave equation is obtained from Einstein's equations and how many and how are the polarization modes of these waves. It is discussed the reasons why GWs sources should be of astrophysical or cosmological origin. Thus, it is discussed what would be the most likely sources of GWs to be detected by the detectors of GWs currently in operation and those that should be operational in the future, emphasizing in particular the sources involving compact objects. The compact objects such as neutron stars, black holes and binary systems involving compact stars can be important sources of GWs. Last but not least, it is discussed the GWs astrophysics that is already possible to do, in particular involving the compact objects.

  2. Cold Dark Matter as Compact Composite Objects

    CERN Document Server

    Zhitnitsky, A

    2006-01-01

    Dark Matter (DM) being the vital ingredient in the cosmos, still remains a mystery. Standard assumption is that the collisionless cold dark matter (CCDM) particles are represented by some weakly interacting fundamental fields which can not be associated with any standard quarks or leptons. However, recent analyses of structure on galactic and sub-galactic scales have suggested discrepancies and stimulated numerous alternative proposals including, e.g. Self-Interacting dark matter, Self-Annihilating dark matter, Decaying dark matter, to name just a few. We propose the alternative to the standard assumption about the nature of DM particles (which are typically assumed to be weakly interacting fundamental point -like particles, yet to be discovered). Our proposal is based on the idea that DM particles are strongly interacting composite macroscopically large objects which made of well known light quarks (or even antiquarks). The required weakness of the DM particle interactions is guaranteed by a small geometrica...

  3. Observations of Transiting Hot Compact Objects

    CERN Document Server

    Rowe, Jason F; Koch, David; Howell, Steve B; Basri, Gibor; Batalha, Natalie; Brown, Timothy M; Caldwell, Douglas; Cochran, William D; Dunham, Edward; Dupree, Andrea K; Fortney, Jonathan J; Gautier, Thomas N; Gilliland, Ronald L; Jenkins, Jon; Latham, David W; Lissauer, Jack J; Marcy, Geoff; Monet, David G; Sasselov, Dimitar; Welsh, William F

    2010-01-01

    Kepler photometry has revealed two unusual transiting companions orbiting an early A-star and a late B-star. In both cases the occultation of the companion is deeper than the transit. The occultation and transit with follow-up optical spectroscopy reveal a 9400 K early A-star, KOI-74 (KIC 6889235), with a companion in a 5.2 day orbit with a radius of 0.08 Rsun and a 10000 K late B-star KOI-81 (KIC 8823868) that has a companion in a 24 day orbit with a radius of 0.2 Rsun. We infer a temperature of 12250 K for KOI-74b and 13500 K for KOI-81b. We present 43 days of high duty cycle, 30 minute cadence photometry, with models demonstrating the intriguing properties of these object, and speculate on their nature.

  4. Thermal slow evolution of compact objects

    CERN Document Server

    Becerra, L; Nunez, L A

    2013-01-01

    We present a comparative study on the gravitational dissipative collapse for local and nonlocal anisotropic spherical matter configurations in the slow contraction approximation. The matter contents are radiant, anisotropic (unequal stresses) spherical local and nonlocal fluids, where the heat flux is described by causal thermodynamics, leading to a consistent determination of the temperature. It is found that both, local and nonlocal, matter configurations exhibit thermal peeling when most of the radiated energy comes from the outer layers of the distribution. This peeling occurs when different signs in the velocity of fluid elements appears, giving rise to the splitting of the matter configuration. This effect emerges as a combination of convection mass transfer and radiation flux, but is the intense radiation field at the outer layers of the object that causes of the peeling. This effect seems to be more violent for nonlocal configurations and it is very sensible to the initial mass of the energy flux prof...

  5. 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...

  6. Compact nuclear objects and properties of their parent galaxies

    CERN Document Server

    Zasov, Anatoly

    2013-01-01

    We consider the relationship between the masses of the compact nuclear objects in the centers of disky galaxies -- supermassive black holes (SMBHs) or nuclear star clusters (NCs) -- and such parameters as the maximal velocity of rotation $V_{\\textrm{max}}$, obtained from the rotation curves, indicative dynamical mass $M_{25}$, and the color index ($B{-}V$) of their parent galaxies. It was found that the mass of nuclear clusters $M_{\\rm nc}$ correlates more closely with the velocity of rotation and total mass of galaxies than the mass of supermassive black holes $M_{\\rm bh}$. The dependence of masses of the central objects on the color index is bimodal: galaxies of the red group (red-sequence), which have ($B{-}V) > 0.6{-}0.7$, differ from bluer galaxies, by higher values of $M_{\\rm bh}$ for similar host-galaxy parameters. In contrast, in the diagrams for nuclear clusters the "blue" and "red" galaxies form unified sequences. It agrees with scenarios in which most red-group galaxies form as a result of loss of ...

  7. Relativistic models of a class of compact objects

    Indian Academy of Sciences (India)

    Rumi Deb; Bikash Chandra Paul; Ramesh Tikekar

    2012-08-01

    A class of general relativistic solutions in isotropic spherical polar coordinates which describe compact stars in hydrostatic equilibrium are discussed. The stellar models obtained here are characterized by four parameters, namely, , , and of geometrical significance related to the inhomogeneity of the matter content of the star. The stellar models obtained using the solutions are physically viable for a wide range of values of the parameters. The physical features of the compact objects taken up here are studied numerically for a number of admissible values of the parameters. Observational stellar mass data are used to construct suitable models of the compact stars.

  8. Extracting Information from the Gravitational Redshift of Compact Rotating Objects

    Indian Academy of Sciences (India)

    Paul D. Nuñez; Marek Nowakowski

    2010-06-01

    Essential macroscopic internal properties of compact objects can be related to each other with the help of General Relativity. A somewhat familiar example is the relationship between the compactness / and the gravitational redshift for nonrotating bodies. Rotation poses new challenges when trying to relate observed or potentially observed quantities such as the graviational redshift, mass, radius, and angular velocity. Using a perturbative approach, we present an analytical approximation whose purpose is to relate these quantities. Two main results are highlighted: Derivation of a new maximal angular velocity depending only on the mass of the object and a possible estimate of the radius from a measurement of the gravitational redshift.

  9. Dynamics of compact objects clusters: A post-Newtonian study

    OpenAIRE

    Kupi, G.; Amaro-Seoane, P.; Spurzem, R.

    2006-01-01

    Compact object clusters are likely to exist in the centre of some galaxies because of mass segregation. The high densities and velocities reached in them deserves a better understanding. The formation of binaries and their subsequent merging by gravitational radiation emission is important to the evolution of such clusters. We address the evolution of such a system in a relativistic regime. The recurrent mergers at high velocities create an object with a mass much larger than the average. For...

  10. Numerical modeling of core-collapse supernovae and compact objects

    CERN Document Server

    Sumiyoshi, K

    2012-01-01

    Massive stars (M> 10Msun) end their lives with spectacular explosions due to gravitational collapse. The collapse turns the stars into compact objects such as neutron stars and black holes with the ejection of cosmic rays and heavy elements. Despite the importance of these astrophysical events, the mechanism of supernova explosions has been an unsolved issue in astrophysics. This is because clarification of the supernova dynamics requires the full knowledge of nuclear and neutrino physics at extreme conditions, and large-scale numerical simulations of neutrino radiation hydrodynamics in multi-dimensions. This article is a brief overview of the understanding (with difficulty) of the supernova mechanism through the recent advance of numerical modeling at supercomputing facilities. Numerical studies with the progress of nuclear physics are applied to follow the evolution of compact objects with neutrino emissions in order to reveal the birth of pulsars/black holes from the massive stars.

  11. Speeded-up and Compact Visual Codebook for Object Recognition

    OpenAIRE

    B. Mayurathan; A. Ramanan, S. Mahesan; U.A.J. Pinidiyaarachchi

    2013-01-01

    The well known framework in the object recognition literature uses local information extracted at several patches in images which are then clustered by a suitable clustering technique. A visual codebook maps the patch-based descriptors into a fixed-length vector in histogram space to which standard classifiers can be directly applied. Thus, the construction of a codebook is an important step which is usually done by cluster analysis. However, it is still difficult to construct a compact codeb...

  12. Speeded-up and Compact Visual Codebook for Object Recognition

    Directory of Open Access Journals (Sweden)

    B. Mayurathan

    2013-02-01

    Full Text Available The well known framework in the object recognition literature uses local information extracted at several patches in images which are then clustered by a suitable clustering technique. A visual codebook maps the patch-based descriptors into a fixed-length vector in histogram space to which standard classifiers can be directly applied. Thus, the construction of a codebook is an important step which is usually done by cluster analysis. However, it is still difficult to construct a compact codebook with reduced computational cost. This paper evaluates the effectiveness and generalisation performance of the Resource-Allocating Codebook (RAC approach that overcomes the problem of constructing fixed size codebooks that can be used at any time in the learning process and the learning patterns do not have to be repeated. It either allocates a new codeword based on the novelty of a newly seen pattern, or adapts the codebook to fit that observation. Furthermore, we improve RAC to yield codebooks that are more compact. We compare and contrast the recognition performance of RAC evaluated with two distinctive feature descriptors: SIFT and SURF and two clustering techniques: K-means and Fast Reciprocal Nearest Neighbours (fast-RNN algorithms. SVM is used in classifying the image signatures. The entire visual object recognition pipeline has been tested on three benchmark datasets: PASCAL visual object classes challenge 2007, UIUC texture, and MPEG-7 Part-B silhouette image datasets. Experimental results show that RAC is suitable for constructing codebooks due to its wider span of the feature space. Moreover, RAC takes only one-pass through the entire data that slightly outperforms traditional approaches at drastically reduced computing times. The modified RAC performs slightly better than RAC and gives more compact codebook. Future research should focus on designing more discriminative and compact codebooks such as RAC rather than focusing on methods tuned to

  13. Compact objects from gravitational collapse: an analytical toy model

    Energy Technology Data Exchange (ETDEWEB)

    Malafarina, Daniele [Nazarbayev University, Department of Physics, Astana (Kazakhstan); Joshi, Pankaj S. [Tata Institute of Fundamental Research, Mumbai (India)

    2015-12-15

    We develop here a procedure to obtain regular static configurations resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature. (orig.)

  14. Compact objects from gravitational collapse: an analytical toy model

    CERN Document Server

    Joshi, Pankaj S

    2015-01-01

    We develop here a procedure to obtain regular static configurations as resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.

  15. Compact objects from gravitational collapse: an analytical toy model

    Science.gov (United States)

    Malafarina, Daniele; Joshi, Pankaj S.

    2015-12-01

    We develop here a procedure to obtain regular static configurations resulting from dynamical gravitational collapse of a massive matter cloud in general relativity. Under certain general physical assumptions for the collapsing cloud, we find the class of dynamical models that lead to an equilibrium configuration. To illustrate this, we provide a class of perfect fluid collapse models that lead to a static constant density object as limit. We suggest that similar models might possibly constitute the basis for the description of formation of compact objects in nature.

  16. Detection, classification, and tracking of compact objects in video imagery

    Science.gov (United States)

    Carlotto, Mark J.; Nebrich, Mark A.

    2012-06-01

    A video data conditioner (VDC) for automated full-­motion video (FMV) detection, classification, and tracking is described. VDC extends our multi-­stage image data conditioner (IDC) to video. Key features include robust detection of compact objects in motion imagery, coarse classification of all detections, and tracking of fixed and moving objects. An implementation of the detection and tracking components of the VDC on an Apple iPhone is discussed. Preliminary tracking results of naval ships captured during the Phoenix Express 2009 Photo Exercise are presented.

  17. A shrinking Compact Symmetric Object: J11584+2450?

    CERN Document Server

    Tremblay, S E; Helmboldt, J F; Fassnacht, C D; Pearson, T J

    2008-01-01

    We present multi-frequency multi-epoch Very Long Baseline Array (VLBA) observations of J11584+2450. These observations clearly show this source, previously classified as a core-jet, to be a compact symmetric object (CSO). Comparisons between these new data and data taken over the last 9 years shows the edge brightened hot spots retreating towards the core (and slightly to the west) at approximately 0.3c. Whether this motion is strictly apparent or actually physical in nature is discussed, as well as possible explanations, and what implications a physical contraction of J11584+2450 would have for current CSO models.

  18. Workshop I – Black holes and compact objects: Classical aspects

    Indian Academy of Sciences (India)

    B S Ramachandra; C V Vishveshwara

    2000-10-01

    This is a summary of the papers presented in session W1 on the papers submitted to the workshop I on the classical aspects of black holes and compact objects were classified into three categories: (i) theoretical aspects; (ii) astrophysical aspects; (iii) gravitational radiation. The three sessions were devoted each to one of the above categories. The chairmen of the workshop were J Bičák, Charles University, Prague (Czech Republic) and C V Vishveshwara, Indian Institute of Astrophysics, India.

  19. Electromagnetic field and cylindrical compact objects in modified gravity

    Science.gov (United States)

    Yousaf, Z.; Bhatti, M. Zaeem ul Haq

    2016-05-01

    In this paper, we have investigated the role of different fluid parameters particularly electromagnetic field and f(R) corrections on the evolution of cylindrical compact object. We have explored the modified field equations, kinematical quantities and dynamical equations. An expression for the mass function has been found in comparison with the Misner-Sharp formalism in modified gravity, after which different mass-radius diagrams are drawn. The coupled dynamical transport equation have been formulated to discuss the role of thermoinertial effects on the inertial mass density of the cylindrical relativistic interior. Finally, we have presented a framework, according to which all possible solutions of the metric f(R)-Maxwell field equations coupled with static fluid can be written through set of scalar functions. It is found that modified gravity induced by Lagrangians f(R) = αR2, f(R) = αR2 - βR and f(R)=α R^2-β R/1+γ R are likely to host more massive cylindrical compact objects with smaller radii as compared to general relativity.

  20. Radioactively Powered Electromagnetic Counterparts of Compact Object Mergers

    CERN Document Server

    Metzger, B D; Darbha, S; Quataert, E; Arcones, A; Kasen, D; Thomas, R; Nugent, P; Panov, I V; Zinner, N T

    2010-01-01

    The most promising astrophysical sources of kHz gravitational waves (GWs) are the inspiral and merger of binary neutron star(NS)/black hole systems. Maximizing the scientific return of a GW detection will require identifying a coincident electro-magnetic (EM) counterpart. One of the most likely sources of isotropic EM emission from compact object mergers is a supernova-like transient powered by the radioactive decay of heavy elements synthesized in ejecta from the merger. We present the first calculations of the optical transients from compact object mergers that self-consistently determine the radioactive heating using a nuclear reaction network; using this heating rate, we model the light curve with a one dimensional Monte Carlo radiation transfer calculation. For an ejecta mass 1e-2 Msun [1e-3 Msun] the resulting light curve peaks on a timescale ~ 1 day at a V-band luminosity ~ 3e41 [1e41] ergs/s (M_V = -15[-14]); this corresponds to an effective "f" parameter ~3e-6 in the Li-Paczynski toy model. We argue ...

  1. Electromagnetic Counterparts of Gravitational Wave Sources : Mergers of Compact Objects

    CERN Document Server

    Kamble, Atish

    2016-01-01

    Mergers of compact objects are considered prime sources of gravitational waves (GW) and will soon be targets of GW observatories such as the Advanced-LIGO, VIRGO etc. Finding electromagnetic counterparts of these GW sources will be important to understand their nature. We discuss possible electromagnetic signatures of the mergers. We show that the BH-BH mergers could have luminosities which exceed Eddington luminosity from unity to several orders of magnitude depending on the masses of the merging BHs. As a result these mergers could be explosive, release up to $10^{51}$ erg of energy and shine as radio transients. At any given time we expect about a few such transients in the sky at GHz frequencies which could be detected out to about 300 Mpc. It has also been argued that these radio transients would look alike radio supernovae with comparable detection rates. Multi-band follow up could, however, distinguish between the mergers and supernovae.

  2. Relativistic Dynamos in Magnetospheres of Rotating Compact Objects

    CERN Document Server

    Tomimatsu, A

    1999-01-01

    The kinematic evolution of axisymmetric magnetic fields in rotating magnetospheres of relativistic compact objects is analytically studied, based on relativistic Ohm's law in stationary axisymmetric geometry. By neglecting the poloidal flows of plasma in simplified magnetospheric models, we discuss self-excited dynamos due to the frame-dragging effect (originally pointed out by Khanna & Camenzind), and we propose alternative processes to generate axisymmetric magnetic fields against ohmic dissipation. The first process (which may be called induced excitation) is caused by the help of a background uniform magnetic field in addition to the dragging of inertial frames. It is shown that excited multipolar components of poloidal and azimuthal fields are sustained as stationary modes, and outgoing Poynting flux converges toward the rotation axis. The second one is self-excited dynamo through azimuthal convection current, which is found to be effective if plasma rotation becomes highly relativistic with a sharp ...

  3. Super-spinning compact objects generated by thick accretion disks

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zilong; Bambi, Cosimo, E-mail: zilongli@fudan.edu.cn, E-mail: bambi@fudan.edu.cn [Center for Field Theory and Particle Physics and Department of Physics, Fudan University, 220 Handan Road, 200433 Shanghai (China)

    2013-03-01

    If astrophysical black hole candidates are the Kerr black holes predicted by General Relativity, the value of their spin parameter must be subject to the theoretical bound |a{sub *}| ≤ 1. In this work, we consider the possibility that these objects are either non-Kerr black holes in an alternative theory of gravity or exotic compact objects in General Relativity. We study the accretion process when their accretion disk is geometrically thick with a simple version of the Polish doughnut model. The picture of the accretion process may be qualitatively different from the one around a Kerr black hole. The inner edge of the disk may not have the typical cusp on the equatorial plane any more, but there may be two cusps, respectively above and below the equatorial plane. We extend previous work on the evolution of the spin parameter and we estimate the maximum value of a{sub *} for the super-massive black hole candidates in galactic nuclei. Since measurements of the mean radiative efficiency of AGNs require η > 0.15, we infer the ''observational'' bound |a{sub *}|∼<1.3, which seems to be quite independent of the exact nature of these objects. Such a bound is only slightly weaker than |a{sub *}|∼<1.2 found in previous work for thin disks.

  4. Super-spinning compact objects generated by thick accretion disks

    International Nuclear Information System (INIS)

    If astrophysical black hole candidates are the Kerr black holes predicted by General Relativity, the value of their spin parameter must be subject to the theoretical bound |a*| ≤ 1. In this work, we consider the possibility that these objects are either non-Kerr black holes in an alternative theory of gravity or exotic compact objects in General Relativity. We study the accretion process when their accretion disk is geometrically thick with a simple version of the Polish doughnut model. The picture of the accretion process may be qualitatively different from the one around a Kerr black hole. The inner edge of the disk may not have the typical cusp on the equatorial plane any more, but there may be two cusps, respectively above and below the equatorial plane. We extend previous work on the evolution of the spin parameter and we estimate the maximum value of a* for the super-massive black hole candidates in galactic nuclei. Since measurements of the mean radiative efficiency of AGNs require η > 0.15, we infer the ''observational'' bound |a*|∼*|∼<1.2 found in previous work for thin disks

  5. Dating COINS: Kinematic Ages for Compact Symmetric Objects

    CERN Document Server

    Gugliucci, N E; Peck, A B; Giroletti, M

    2004-01-01

    We present multi-epoch VLBA observations of Compact Symmetric Objects (CSOs) from the COINS sample (CSOs Observed In the Northern Sky). These observations allow us to make estimates of, or place limits on, the kinematic ages for those sources with well-identified hot spots. This study significantly increases the number of CSOs with well-determined ages or limits. The age distribution is found to be sharply peaked under 500 years, suggesting that many CSOs die young, or are episodic in nature, and very few survive to evolve into FR II sources like Cygnus A. Jet components are found to have higher velocities than hot spots which is consistent with their movement down cleared channels. We also report on the first detections of significant polarization in two CSOs, J0000+4054 (2.1%) and J1826+1831 (8.8%). In both cases the polarized emission is found in jet components on the stronger side of the center of activity.

  6. Relativistic Dynamos in Magnetospheres of Rotating Compact Objects

    Science.gov (United States)

    Tomimatsu, Akira

    2000-01-01

    The kinematic evolution of axisymmetric magnetic fields in rotating magnetospheres of relativistic compact objects is analytically studied, based on relativistic Ohm's law in stationary axisymmetric geometry. By neglecting the poloidal flows of plasma in simplified magnetospheric models, we discuss a self-excited dynamo due to the frame-dragging effect (originally pointed out by Khanna & Camenzind) and propose alternative processes to generate axisymmetric magnetic fields against ohmic dissipation. The first process (which may be called ``induced excitation'') is caused by the help of a background uniform magnetic field in addition to the dragging of inertial frames. It is shown that excited multipolar components of poloidal and azimuthal fields are sustained as stationary modes, and outgoing Poynting flux converges toward the rotation axis. The second process is a self-excited dynamo through azimuthal convection current, which is found to be effective if plasma rotation becomes highly relativistic with a sharp gradient in the angular velocity. In this case, no frame-dragging effect is needed, and the coupling between charge separation and plasma rotation becomes important. We discuss briefly the results in relation to active phenomena in the relativistic magnetospheres.

  7. Binary compact object coalescence rates: The role of elliptical galaxies

    CERN Document Server

    O'Shaughnessy, R; Belczynski, K

    2009-01-01

    We estimate binary compact object merger detection rates for LIGO, including the binaries formed in ellipticals long ago. Specifically, we convolve hundreds of model realizations of elliptical- and spiral-galaxy population syntheses with a model for elliptical- and spiral-galaxy star formation history as a function of redshift. Our results favor local merger rate densities of 4\\times 10^{-3} {Mpc}^{-3}{Myr}^{-1} for binary black holes (BH), 3\\times 10^{-2} {Mpc}^{-3}{Myr}^{-1} for binary neutron stars (NS), and 10^{-2} {Mpc}^{-3}{Myr}^{-1} for BH-NS binaries. Mergers in elliptical galaxies are a significant fraction of our total estimate for BH-BH and BH-NS detection rates; NS-NS detection rates are dominated by the contribution from spiral galaxies. Using only models that reproduce current observations of Galactic NS-NS binaries, we find slightly higher rates for NS-NS and largely similar ranges for BH-NS and BH-BH binaries. Assuming a detection signal-to-noise ratio threshold of 8 for a single detector (as ...

  8. Compact object formation and the supernova explosion engine

    International Nuclear Information System (INIS)

    When a massive star ends its life, its core collapses, forming a neutron star or black hole and producing some of the most energetic explosions in the universe. Core-collapse supernovae and long-duration gamma-ray bursts are the violent signatures of compact remnant formation. As such, both fields are intertwined and, coupled with theory, observations of transients can help us better understand compact remnants just as neutron star and black hole observations can constrain the supernova and gamma-ray burst engine. We review these ties in this paper. (paper)

  9. Eccentric binaries of compact objects in strong-field gravity

    International Nuclear Information System (INIS)

    In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on to the

  10. Eccentric binaries of compact objects in strong-field gravity

    Energy Technology Data Exchange (ETDEWEB)

    Gold, Roman

    2011-09-27

    In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on

  11. An X-ray View of the Zoo of Compact Objects and Associated Supernova Remnants

    Science.gov (United States)

    Safi-Harb, Samar

    2015-08-01

    Core-collapse explosions of massive stars leave behind some of the most exotic compact objects in the Universe. These include: rotation-powered pulsars like the Crab, powering pulsar wind nebulae (PWNe) observed across the electromagnetic spectrum; highly magnetized neutron stars ("magnetars") shining or bursting at high-energies; and X-ray emitting “Central Compact Objects” (CCOs) with intrinsic properties and emission mechanism that remain largely unknown. I will highlight this observed diversity of compact stellar remnants from an X-ray perspective, and address the connection between their properties and those of their hosting supernova remnants (SNRs). In particular I will highlight topics related to their formation and evolution, including: 1) which supernovae make magnetars and the shell-less PWNe?, 2) what can we learn from the apparent age discrepancy between SNRs and their associated pulsars? I will conclude with prospects for observations of SNRs with the upcoming ASTRO-H X-ray mission. The unprecedented spectral resolution on board of ASTRO-H’s micro-calorimeter will particularly open a new discovery window for supernova progenitors' science.

  12. Time evolution of accreting magnetofluid around a compact object-Newtonian analysis

    Science.gov (United States)

    Habibi, Fahimeh; Shaghaghian, Mahboobeh; Pazhouhesh, Reza

    2015-07-01

    Time evolution of a thick disc with finite conductivity around a nonrotating compact object is presented. Along with the Maxwell equations and the Ohm's law, the Newtonian limit of the relativistic fluid equations governing the motion of a finitely conducting plasma is derived. The magnetofluid is considered to possess only the poloidal components of the electromagnetic field. Moreover, the shear viscous stress is neglected, as well as the self-gravity of the disc. In order to solve the equations, we have used a self-similar solution. The main features of this solution are as follows. The azimuthal velocity is somewhat increased from the Keplerian value in the equator plane to the super-Keplerian values at the surface of disc. Moreover, the radial velocity is obtained proportional to the meridional velocity. Magnetofluid does not have any nonzero component of the current density. Subsequently, the electromagnetic force is vanished and does not play any role in the force balance. While the pressure gradient maintains the disc structure in latitudinal direction, magnetofluid has no accretion on the central compact object. Analogously to the parameter α in the standard model, our calculations contain one parameter η0 which specifies the size of the electrical resistivity.

  13. Nonconformally flat initial data for binary compact objects

    International Nuclear Information System (INIS)

    A new method is described for constructing initial data for a binary neutron-star system in quasiequilibrium circular orbit. Two formulations for nonconformally flat data, waveless and near-zone helically symmetric, are introduced; in each formulation, the Einstein-Euler system, written in 3+1 form on an asymptotically flat spacelike hypersurface, is exactly solved for all metric components, including the spatially nonconformally flat potentials, and for irrotational flow. A numerical method applicable to both formulations is explained with an emphasis on the imposition of a spatial gauge condition. Results are shown for solution sequences of irrotational binary neutron-stars with matter approximated by parametrized equations of state that use a few segments of polytropic equations of state. The binding energy and total angular momentum of solution sequences computed within the conformally flat--Isenberg-Wilson-Mathews--formulation are closer to those of the third post-Newtonian (3PN) two point particles up to the closest orbits, for the more compact stars, whereas sequences resulting from the waveless/near-zone helically symmetric formulations deviate from the 3PN curve even more for the sequences with larger compactness. We think it likely that this correction reflects an overestimation in the Isenberg-Wilson-Mathews formulation as well as in the 3PN formula, by ∼1 cycle in the gravitational-wave phase during the last several orbits. The work suggests that imposing spatial conformal flatness results in an underestimate of the quadrupole deformation of the components of binary neutron-star systems in the last few orbits prior to merger.

  14. Tidal torque induced by orbital decay in compact object binaries

    CERN Document Server

    Dall'Osso, Simone

    2012-01-01

    As we observe in the moon-earth system, tidal interactions in binaries can lead to angular momentum exchange. The presence of viscosity is generally regarded as the condition for such transfer to happen. In this paper, we how a dynamical mechanism can cause a persistent torque between the binary components, even for inviscid bodies. This preferentially occurs at the final stage of coalescence of compact binaries, when the orbit shrinks by gravitational waves on a timescale shorter than the viscous timescale. The total orbital energy transferred to the secondary is a few 10^(-3) of its binding energy. We further show that this persistent torque induces a differentially rotating quadrupolar perturbation. Specializing to the case of a neutron star, we find that the free energy associated with this non-equilibrium state can be at least ~ 5 \\times 10^(46) erg just prior to coalescence. This energy is likely stored in internal fluid motions, with a sizable amount of differential rotation. Thus, a preexisting magnet...

  15. The Fate of Fallback Matter around Newly Born Compact Objects

    Science.gov (United States)

    Perna, Rosalba; Duffell, Paul; Cantiello, Matteo; MacFadyen, Andrew I.

    2014-02-01

    The presence of fallback disks around young neutron stars (NSs) has been invoked over the years to explain a large variety of phenomena. Here we perform a numerical investigation of the formation of such disks during a supernova (SN) explosion, considering both NS and black hole (BH) remnants. Using the public code MESA, we compute the angular momentum distribution of the pre-SN material, for stars with initial masses M in the range 13-40 M ⊙, initial surface rotational velocities v surf between 25% and 75% of the critical velocity, and for metallicities Z of 1%, 10%, and 100% of the solar value. These pre-SN models are exploded with energies E varying between 1050-3 × 1052 erg, and the amount of fallback material is computed. We find that, if magnetic torques play an important role in angular momentum transport, then fallback disks around NSs, even for low-metallicity main-sequence stars, are not an outcome of SN explosions. Formation of such disks around young NSs can only happen under the condition of negligible magnetic torques and a fine-tuned explosion energy. For those stars that leave behind BH remnants, disk formation is ubiquitous if magnetic fields do not play a strong role; however, unlike the NS case, even with strong magnetic coupling in the interior, a disk can form in a large region of the Z, M, v surf, E parameter space. Together with the compact, hyperaccreting fallback disks widely discussed in the literature, we identify regions in the above parameter space that lead to extended, long-lived disks around BHs. We find that the physical conditions in these disks may be conducive to planet formation, hence leading to the possible existence of planets orbiting BHs.

  16. The fate of fallback matter around newly Born compact objects

    International Nuclear Information System (INIS)

    The presence of fallback disks around young neutron stars (NSs) has been invoked over the years to explain a large variety of phenomena. Here we perform a numerical investigation of the formation of such disks during a supernova (SN) explosion, considering both NS and black hole (BH) remnants. Using the public code MESA, we compute the angular momentum distribution of the pre-SN material, for stars with initial masses M in the range 13-40 M ☉, initial surface rotational velocities v surf between 25% and 75% of the critical velocity, and for metallicities Z of 1%, 10%, and 100% of the solar value. These pre-SN models are exploded with energies E varying between 1050-3 × 1052 erg, and the amount of fallback material is computed. We find that, if magnetic torques play an important role in angular momentum transport, then fallback disks around NSs, even for low-metallicity main-sequence stars, are not an outcome of SN explosions. Formation of such disks around young NSs can only happen under the condition of negligible magnetic torques and a fine-tuned explosion energy. For those stars that leave behind BH remnants, disk formation is ubiquitous if magnetic fields do not play a strong role; however, unlike the NS case, even with strong magnetic coupling in the interior, a disk can form in a large region of the Z, M, v surf, E parameter space. Together with the compact, hyperaccreting fallback disks widely discussed in the literature, we identify regions in the above parameter space that lead to extended, long-lived disks around BHs. We find that the physical conditions in these disks may be conducive to planet formation, hence leading to the possible existence of planets orbiting BHs.

  17. The First Compact Objects in the MOND Model

    International Nuclear Information System (INIS)

    We trace the evolution of a spherically symmetric density perturbation in the MOdified Newtonian Dynamics (MOND) model. The background cosmological model is a Λ-dominated, low-Ωb Friedmann model with no Cold Dark Matter. We include thermal processes and non-equilibrium chemical evolution of the collapsing gas. We find that the first density perturbations which collapse to form luminous objects have mass ∼ 105 Mo. The time of the final collapse of these objects depends mainly on the value of the MOND acceleration a0 and also on the baryon density Ωb. For the ''standard'' value a0=1.2x10-8 cm/s2 the collapse starts at redshift z∼160 for Ωb = 0.05 and z∼110 for Ωb=0.02. (author)

  18. Compact and extended objects from self-interacting phantom fields

    CERN Document Server

    Dzhunushaliev, Vladimir; Makhmudov, Arislan; Urazalina, Ainur; Singleton, Douglas; Scott, John

    2016-01-01

    In this work we investigate localized and extended objects for gravitating, self-interacting phantom fields. The phantom fields come from two scalar fields with a "wrong sign" (negative) kinetic energy term in the Lagrangian. This study covers several solutions supported by these phantom fields: phantom balls, traversable wormholes, phantom cosmic strings, and "phantom" domain walls. These four systems are solved numerically and we try to draw out general, interesting features in each case.

  19. Exact Solutions for Compact Objects in General Relativity

    CERN Document Server

    Raghoonundun, Ambrish M

    2016-01-01

    Seven new solutions to the interior static and spherically symmetric Einstein's field equations (EFE) are found and investigated. These new solutions are a generalisation of the quadratic density fall-off profile of the Tolman VII solution. The generalisation involves the addition of anisotropic pressures and electric charge to the density profile. Of these new solutions three are found to obey all the necessary conditions of physical acceptability, including linear stability under radial perturbations, and causality of the speed of pressure waves inside the object. Additionally an equation of state can be found for all the physically viable solutions. The generalised pulsation equation for interior solutions to the EFE that include both electric charge and pressure anisotropy is derived and used to determine the stability of the solutions. However the pulsation equation found is general and can be used for all new solutions that contain these ingredients.

  20. Strong gravitational lensing by a Konoplya-Zhidenko rotating non-Kerr compact object

    CERN Document Server

    Wang, Shangyun; Jing, Jiliang

    2016-01-01

    Konoplya and Zhidenko have proposed recently a rotating non-Kerr black hole metric beyond General Relativity and make an estimate for the possible deviations from the Kerr solution with the data of GW 150914. We here study the strong gravitational lensing in such a rotating non-Kerr spacetime with an extra deformation parameter. We find that the condition of existence of horizons is not inconsistent with that of the marginally circular photon orbit. Moreover, the deflection angle of the light ray near the weakly naked singularity covered by the marginally circular orbit diverges logarithmically in the strong-field limit, but in the case of the completely naked singularity, it is a nagetive finite value as in the Janis-Newman-Winicour spacetime. These properties of strong gravitational lensing are different from those in the Johannsen-Psaltis rotating non-Kerr spacetime. Modeling the supermassive central object of the Milk Way Galaxy as a Konoplya-Zhidenko rotating non-Kerr compact object, we estimated the num...

  1. Mass bounds for compact spherically symmetric objects in generalized gravity theories

    CERN Document Server

    Burikham, Piyabut; Lake, Matthew J

    2016-01-01

    We derive upper and lower bounds on the mass-radius ratio of stable compact objects in extended gravity theories, in which modifications of the gravitational dynamics via-{\\' a}-vis standard general relativity are described by an effective contribution to the matter energy-momentum tensor. Our results include the possibility of a variable coupling between the matter sector and the gravitational field and are valid for a large class of generalized gravity models. The generalized continuity and Tolman-Oppenheimer-Volkoff equations are expressed in terms of the effective mass, density and pressure, given by the bare values plus additional contributions from the total energy-momentum tensor, and general theoretical limits for the maximum and minimum mass-radius ratios are explicitly obtained. As an applications of the formalism developed herein, we consider compact bosonic objects, described by scalar-tensor gravitational theories with self-interacting scalar field potentials, and charged compact objects, respect...

  2. GR-AMRVAC code applications: accretion onto compact objects, boson stars versus black holes

    Science.gov (United States)

    Meliani, Z.; Grandclément, P.; Casse, F.; Vincent, F. H.; Straub, O.; Dauvergne, F.

    2016-08-01

    In the close vicinity of a compact object strong gravity imprints its signature onto matter. Systems that contain at least one compact object are observed to exhibit extreme physical properties and typically emit highly energetic radiation. The nature of the compact objects that produce the strongest gravitational fields is to date not settled. General relativistic numerical simulations of fluid dynamics around black holes, neutron stars, and other compact objects such as boson stars (BSs) may give invaluable insights into this fundamental question. In order to study the behavior of fluid in the strong gravity regime of an arbitrary compact object we develop a new general relativistic hydrodynamics code. To this end we extend the existing versatile adaptive mesh refinement code MPI-AMRVAC into a general relativistic hydrodynamics framework and adapt it for the use of numerically given spacetime metrics. In the present article we study accretion flows in the vicinity of various types of BSs whose numerical metrics are calculated by the KADATH spectral solver library. We design specific tests to check the reliability of any code intending to study BSs and compare the solutions with those obtained in the context of Schwarzschild black holes. We perform the first ever general relativistic hydrodynamical simulations of gas accretion by a BS. The behavior of matter at small distances from the center of a BS differs notably from the black hole case. In particular we demonstrate that in the context of Bondi spherical accretion the mass accretion rate onto non-rotating BSs remains constant whereas it increases for Schwarzschild black holes. We also address the scenario of non-spherical accretion onto BSs and show that this may trigger mass ejection from the interior of the BS. This striking feature opens the door to forthcoming investigations regarding accretion-ejection flows around such types of compact objects.

  3. VLBA OBSERVATIONS OF H I IN THE ARCHETYPE COMPACT SYMMETRIC OBJECT B2352+495

    International Nuclear Information System (INIS)

    B2352+495 is a prototypical example of a compact symmetric object. It has a double radio lobe symmetrically located with respect to a central flat-spectrum radio core (the location of the active galactic nucleus) and has a physical extent of less than 200 pc. In this work, we report Very Long Baseline Array observation of 21 cm H I absorption toward B2352+495 to investigate the properties of this remarkable radio source, in particular, to explore whether the radio emission can be confined by circumnuclear material (frustration scenario) or whether the source is likely to be young. We confirmed the two H I absorption features previously detected toward B2352+495-a broad line nearly centered at the systemic velocity of the galaxy and a narrow redshifted component. The atomic gas from the broad absorption component is likely associated with circumnuclear material, consistent with the current paradigm of clumpy H I distribution in toroidal structures around supermassive black holes.

  4. Compact planetary nebulae in the Galactic disk: Analysis of the central stars

    Science.gov (United States)

    Moreno-Ibáñez, Manuel; Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia

    2016-09-01

    Context. We have obtained multi-wavelength observations of compact Galactic planetary nebulae (PNe) to probe post-asymptotic giant branch (AGB) evolution from the onset of nebular ejection. Here we analyze new observations from HST to derive the masses and evolutionary status of their central stars (CSs). Aims: Our objective here is to derive the masses of the CSs hosted by compact PNe in order to better understand the relationship between the CS properties and those of the surrounding nebulae. We also compare this sample with others we obtained using the same technique in different metallicity environments: the Large and Small Magellanic Clouds. Methods: This paper is based on HST/WFC3 images of 51 targets obtained in a snapshot survey (GO-11657). The high spatial resolution of HST allows us to resolve these compact PNe and distinguish the CS emission from that of their surrounding PNe. We derive CS bolometric luminosities and effective temperatures using the Zanstra technique, from a combination of HST photometry and ground-based spectroscopic data. The targets were imaged through the filters F200LP, F350LP, and F814W from which we derive Johnson V and I magnitudes. We infer CS masses by placing the stars on a temperature-luminosity diagram and compare their location with the best available, single star post-AGB evolutionary tracks. Results: We present new, unique photometric measurements of 50 CSs, and we derive effective temperatures and luminosities for most of them. Central star masses for 23 targets were derived with the evolutionary track technique; the remaining masses were indeterminate most likely because of underestimates of the stellar temperature, or because of substantial errors in the adopted statistical distances to these objects. We expect these problems will be largely overcome when the Gaia distance catalog becomes available. We find that objects with the higher ratios of Zanstra temperatures T(H i)/T( He ii ) tend to have lower-mass progenitors

  5. A transition of urban compactness of Tokyo central during past 3 decades with Landsat data

    Science.gov (United States)

    Tanaka, S.; Nakaohkubo, K.; Ninomiya, A.; Kita, H.; Hoyano, A.; Hashiba, H.

    Urban system consists of two aspects urban efficiency and conformability Concentration of multi and large functions of urbanized area promotes the efficiency of human works in the urbanized area while open space has given conformability to people in their urban life Though the conformability of the urban space has been studied by various researches the study of urban efficiency has been rare A concept of compactness seen on Zhang s paper of IGARSS2005 is a kind of measure to express urban efficiency The compactness reaches the maximum value 2 when the urbanized area makes a circle The value ranges from 0 to 2 theoretically when the urban area expands horizontally Vertical urban development makes a different feature in this value variation Supposing a case of high story building in the urban central the value of compactness exceeds the value 2 A concept of compactness seen on Zhang s paper could be modified to be applied for this three dimensional evaluation of urban efficiency This paper gives a primitive model of urban expansion patterns taking the corresponding compactness values 0 1 2 and 3 Extracting a circle area with 2km radius foot accessible area in Tokyo central the transition of compactness during past 3 decades is estimated from Landsat data Value of compactness grows gradually beyond 2 in the area namely indicating the urban growing in vertical

  6. 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...

  7. Survey of soil compaction on oil and gas leases in east-central Alberta

    International Nuclear Information System (INIS)

    A study was conducted to examine reasons for topsoil compaction at oil and gas well-sites. A survey of 20 well-sites in east-central Alberta was was made, comparing the six methods which are commonly used to evaluate soil compaction. The methods described were: bulk density, bulk density corrected for organic matter content, total porosity, estimated hydraulic conductivity, mechanical impedance, and macro-pore volume. The survey was also used to evaluate the extent of soil compaction on well-sites with different soil types and different reclamation conditions. It was shown that about one third of the well-sites had higher mechanical impedance than the adjacent farmland soils. The probable causes for topsoils being more frequently compacted than subsoils were also described. 33 refs., 10 tabs., 4 figs

  8. Many faces of compact objects: distance, optical extinction and multi-wavelength behaviour

    International Nuclear Information System (INIS)

    This thesis is devoted to a multi-wavelength study of accretion-ejection phenomena around compact stars (black holes and neutron stars). The first part of this manuscript describes problems related to the determination of the distance and the optical extinction to compact objects - fundamental parameters for the evaluation of the energy budget of these systems. To this end, the structure and the dynamics of the Galaxy are studied by observations of the atomic and molecular gas along the line of sight to compact stars. This method leads to the first evaluation of the distance to two Soft Gamma Repeaters: SGR 1806-20 and SGR 1627-41. We then draw some conclusions on the nature of these sources of recurrent gamma-ray bursts. The above method is then applied to two X-ray binaries: Cir X-1 and GX 339-4. In the second part of this thesis, we present a multi-wavelength study of the Galactic black hole candidate GX 339-4. We first discuss the characteristics of the radio emission from GX 339-4. In 1998, GX 339-4 underwent a transition to a soft-high X-ray state and observations in three wavelength regimes (radio, soft and hard X-rays) revealed new patterns of behaviour. This allowed us to constrain the region of origin of the radio emission (a compact jet) in GX 339-4 and allowed a better understanding of the physical coupling between accretion and ejection in GX 339-4. An analogy with the black hole candidate Cyg X-1 is then presented. Finally, these results are discussed in the context of micro-quasars and active galactic nuclei in order to gain a deeper insight into the accretion-ejection coupling around compact objects. (author)

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

    OpenAIRE

    Corbel, S.; Miller-Jones, J. C. A.; 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.; J. Strader(Michigan State University); Woudt, 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 a...

  10. A new direction for dark matter research: intermediate mass compact halo objects

    OpenAIRE

    Chapline, G.; Frampton, P. H.

    2016-01-01

    The failure to find evidence for elementary particles that could serve as the constituents of dark matter brings to mind suggestions that dark matter might consist of massive compact objects (MACHOs). In particular, it has recently been argued that MACHOs with masses > 15 solar masses may have been prolifically produced at the onset of the big bang. Although a variety of astrophysical signatures for primordial MACHOs with masses in this range have been discussed in the literature, we favor a ...

  11. Evolution of the spin parameter of accreting compact objects with non-Kerr quadrupole moment

    International Nuclear Information System (INIS)

    There is robust observational evidence supporting the existence of 5−20 Msun compact bodies in X-ray binary systems and of 105−109 Msun bodies at the center of many galaxies. All these objects are commonly interpreted as black holes, even is there is no direct evidence that they have an event horizon. A fundamental limit for a black hole in 4-dimensional general relativity is the Kerr bound |a*| ≤ 1, where a* is the spin parameter. This is just the condition for the existence of the event horizon. The accretion process can spin a black hole up to a* ≈ 0.998 and some super-massive objects in galactic nuclei could be rapidly rotating black holes with spin parameter close to this limit. However, if these super-massive objects are not black holes, the Kerr bound does not hold and the accretion process can spin them up to a* > 1. In this paper, I consider compact bodies with non-Kerr quadrupole moment. I study the evolution of the spin parameter due to accretion and I find its equilibrium value. Future experiments like the gravitational wave detector LISA will be able to test if the super-massive objects at the center of galaxies are the black holes predicted by general relativity. If they are not black holes, some of them may be super-spinning objects with a* > 1

  12. The multimessenger picture of compact object encounters: binary mergers versus dynamical collisions

    Science.gov (United States)

    Rosswog, S.; Piran, T.; Nakar, E.

    2013-04-01

    We explore the multimessenger signatures of encounters between two neutron stars (ns2) and between a neutron star and a stellar mass black hole (nsbh). We focus on the differences between gravitational-wave-driven binary mergers and dynamical collisions that occur, for example, in globular clusters. Our discussion is based on Newtonian hydrodynamics simulations that incorporate a nuclear equation of state and a multiflavour neutrino treatment. For both types of encounters we compare the gravitational wave and neutrino emission properties. We also calculate the rates at which nearly unbound mass is delivered back to the central remnant in a ballistic-fallback-plus-viscous-disc model and we analyse the properties of the dynamically ejected matter. Last but not least we address the electromagnetic transients that accompany each type of encounter. We find that dynamical collisions are at least as promising as binary mergers for producing (short) gamma-ray bursts, but they also share the same possible caveats in terms of baryonic pollution. All encounter remnants produce peak neutrino luminosities of at least ˜1053 erg s-1, some of the collision cases exceed this value by more than an order of magnitude. The canonical ns2 merger case ejects more than 1 per cent of a solar mass of extremely neutron-rich (Ye ˜ 0.03) material, an amount that is consistent with double neutron star mergers being a major source of r-process in the galaxy. nsbh collisions eject very large amounts of matter (˜0.15 M⊙) which seriously constrains their admissible occurrence rates. The compact object collision rate (sum of ns2 and nsbh) must therefore be less, likely much less, than 10 per cent of the ns2 merger rate. The radioactively decaying ejecta produce optical-ultraviolet `macronova' which, for the canonical merger case, peak after ˜0.4 d with a luminosity of ˜5 × 1041 erg s-1. ns2 (nsbh) collisions reach up to two (four) times larger peak luminosities. The dynamic ejecta deposit a

  13. Reionization Constraints on the Contribution of Primordial Compact Objects to Dark Matter

    CERN Document Server

    Miller, M C

    2000-01-01

    Many lines of evidence suggest that nonbaryonic dark matter constitutes roughly 300f the critical closure density, but the composition of this dark matter is unknown. One class of candidates for the dark matter is compact objects formed in the early universe, with typical masses M between 0.1 and 1 solar masses to correspond to the mass scale of objects found with microlensing observing projects. Specific candidates of this type include black holes formed at the epoch of the QCD phase transition, quark stars, and boson stars. Here we show that accretion onto these objects produces substantial ionization in the early universe, with an optical depth to Thomson scattering out to z=1100 of approximately tau=2-4 [f_CO\\epsilon_{-1}(M/Msun)]^{1/2} (H_0/65)^{-1}, where \\epsilon_{-1} is the accretion efficiency \\epsilon\\equiv L/{\\dot M}c^2 divided by 0.1 and f_CO is the fraction of matter in the compact objects. The current upper limit to the scattering optical depth, based on the anisotropy of the microwave backgroun...

  14. A General Relativistic Model for Magnetic Monopole-Infused Compact Objects

    CERN Document Server

    Pazameta, Zoran

    2012-01-01

    Emergent concepts from astroparticle physics are incorporated into a classical solution of the Einstein-Maxwell equations for a binary magnetohydrodynamic fluid, in order to describe the final equilibrium state of compact objects infused with magnetic monopoles produced by proton-proton collisions within the intense dipolar magnetic fields generated by these objects during their collapse. It is found that the effective mass of such an object's acquired monopolar magnetic field is three times greater than the mass of its native fluid and monopoles combined, necessitating that the interior matter undergo a transition to a state of negative pressure in order to attain equilibrium. Assuming full symmetry between the electric and magnetic Maxwell equations yields expressions for the monopole charge density and magnetic field by direct analogy with their electrostatic equivalents; inserting these into the Einstein equations then leads to an interior metric which is well-behaved from the origin to the surface, where...

  15. Compact dark matter objects, asteroseismology, and gravitational waves radiated by sun

    International Nuclear Information System (INIS)

    The solar surface oscillations observed by Crimean Astrophysical Observatory and Solar Helioseismic Observatory are considered to be excited by a small fraction of Dark Matter in form of Compact Dark Matter Objects (CDMO) in the solar structure. Gravitational Waves (GW) radiated by these CDMO are predicted to be the strongest at the Earth and are easily detectable by European Laser Interferometer Space Antenna or by Gravitational-Wave Observatory “Dulkyn” which can solve two the most challenging tasks in the modern physics: direct detection of GW and DM

  16. Compact dark matter objects, asteroseismology, and gravitational waves radiated by sun

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovsky, Yu. E., E-mail: Pokrovskiy-YE@nrcki.ru [National Research Center Kurchatov Institute (Russian Federation)

    2015-12-15

    The solar surface oscillations observed by Crimean Astrophysical Observatory and Solar Helioseismic Observatory are considered to be excited by a small fraction of Dark Matter in form of Compact Dark Matter Objects (CDMO) in the solar structure. Gravitational Waves (GW) radiated by these CDMO are predicted to be the strongest at the Earth and are easily detectable by European Laser Interferometer Space Antenna or by Gravitational-Wave Observatory “Dulkyn” which can solve two the most challenging tasks in the modern physics: direct detection of GW and DM.

  17. Bounds on the basic physical parameters for anisotropic compact general relativistic objects

    Energy Technology Data Exchange (ETDEWEB)

    Boehmer, C G [ASGBG/CIU, Department of Mathematics, Apartado Postal C-600, University of Zacatecas (UAZ), Zacatecas, Zac 98060 (Mexico); Harko, T [Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pokfulam Road, Hong Kong (China)

    2006-11-21

    We derive the upper and lower limits for the basic physical parameters (mass-radius ratio, anisotropy, redshift and total energy) for arbitrary anisotropic general relativistic matter distributions in the presence of a cosmological constant. The values of these quantities are strongly dependent on the value of the anisotropy parameter (the difference between the tangential and radial pressure) at the surface of the star. In the presence of the cosmological constant, a minimum mass configuration with a given anisotropy does exist. Anisotropic compact stellar-type objects can be much more compact than the isotropic ones, and their radii may be close to their corresponding Schwarzschild radii. Upper bounds for the anisotropy parameter are also obtained from the analysis of the curvature invariants. General restrictions for the redshift and the total energy (including the gravitational contribution) for anisotropic stars are obtained in terms of the anisotropy parameter. Values of the surface redshift parameter greater than two could be the main observational signature for anisotropic stellar-type objects.

  18. Bounds on the basic physical parameters for anisotropic compact general relativistic objects

    International Nuclear Information System (INIS)

    We derive the upper and lower limits for the basic physical parameters (mass-radius ratio, anisotropy, redshift and total energy) for arbitrary anisotropic general relativistic matter distributions in the presence of a cosmological constant. The values of these quantities are strongly dependent on the value of the anisotropy parameter (the difference between the tangential and radial pressure) at the surface of the star. In the presence of the cosmological constant, a minimum mass configuration with a given anisotropy does exist. Anisotropic compact stellar-type objects can be much more compact than the isotropic ones, and their radii may be close to their corresponding Schwarzschild radii. Upper bounds for the anisotropy parameter are also obtained from the analysis of the curvature invariants. General restrictions for the redshift and the total energy (including the gravitational contribution) for anisotropic stars are obtained in terms of the anisotropy parameter. Values of the surface redshift parameter greater than two could be the main observational signature for anisotropic stellar-type objects

  19. The rotational broadening of V395 Car - implications on compact object's mass

    CERN Document Server

    Shahbaz, T

    2007-01-01

    CONTEXT: The masses previously obtained for the X-ray binary 2S0921-630 inferred a compact object that was either a high-mass neutron star or low-mass black-hole, but used a previously published value for the rotational broadening (vsini) with large uncertainties. AIMS: We aim to determine an accurate mass for the compact object through an improved measurement of the secondary star's projected equatorial rotational velocity. METHODS: We have used UVES echelle spectroscopy to determine the vsini of the secondary star (V395 Car) in the low-mass X-ray binary 2S0921-630 by comparison to an artificially broadened spectral-type template star. In addition, we have also measured vsini from a single high signal-to-noise ratio absorption line profile calculated using the method of Least-Squares Deconvolution (LSD). RESULTS: We determine vsini to lie between 31.3+/-0.5km/s to 34.7+/-0.5km/s (assuming zero and continuum limb darkening, respectively) in disagreement with revious results based on intermediate resolution sp...

  20. Accretion-caused deceleration of a gravitationally powerful compact stellar object moving within a dense Fermi gas

    Science.gov (United States)

    Tito, E. P.; Pavlov, V. I.

    2016-07-01

    We consider accretion-caused deceleration of a gravitationally-powerful compact stellar object traveling within a cold Fermi-gas medium. We provide analytical and numerical estimates of the effect manifestation.

  1. Accretion-caused deceleration of a gravitationally powerful compact stellar object moving within a dense Fermi gas

    CERN Document Server

    Tito, Elizabeth P

    2016-01-01

    We consider accretion-caused deceleration of a gravitationally-powerful compact stellar object traveling within a cold Fermi-gas medium. We provide analytical and numerical estimates of the effect manifestation.

  2. A synthetic model of the gravitational wave background from evolving binary compact objects

    CERN Document Server

    Dvorkin, Irina; Vangioni, Elisabeth; Silk, Joseph

    2016-01-01

    Modeling the stochastic gravitational wave background from various astrophysical sources is a key objective in view of upcoming observations with ground- and space-based gravitational wave observatories such as Advanced LIGO, VIRGO, eLISA and PTA. We develop a synthetic model framework that follows the evolution of single and binary compact objects in an astrophysical context. We describe the formation and merger rates of binaries, the evolution of their orbital parameters with time and the spectrum of emitted gravitational waves at different stages of binary evolution. Our approach is modular and allows us to test and constrain different ingredients of the model, including stellar evolution, black hole formation scenarios and the properties of binary systems. We use this framework in the context of a particularly well-motivated astrophysical setup to calculate the gravitational wave background from several types of sources, including inspiraling stellar-mass binary black holes that have not merged during a H...

  3. Numerical simulations of axisymmetric hydrodynamical Bondi-Hoyle accretion onto a compact object

    CERN Document Server

    Mellah, Ileyk El

    2015-01-01

    Bondi-Hoyle accretion configurations occur as soon as a gravitating body is immersed in an ambient medium with a supersonic relative velocity. From wind-accreting X-ray binaries to runaway neutron stars, such a regime has been witnessed many times and is believed to account for shock formation, the properties of which can be only marginally derived analytically. In this paper, we present the first results of the numerical characterization of the stationary flow structure of Bondi-Hoyle accretion onto a compact object, from the large scale accretion radius down to the vicinity of the compact body. For different Mach numbers, we study the associated bow shock. It turns out that those simulations confirm the analytical prediction by Foglizzo & Ruffert (1996) concerning the topology of the inner sonic surface with an adiabatic index of 5/3. They also enable us to derive the related mass accretion rates, the position and the temperature of the bow shock, as function of the flow parameters, along with the trans...

  4. Relativistic simulations of compact object mergers for nucleonic matter and strange quark matter

    Energy Technology Data Exchange (ETDEWEB)

    Bauswein, Andreas Ottmar

    2010-01-29

    Under the assumption that the energy of the ground state of 3-flavor quark matter is lower than the one of nucleonic matter, the compact stellar remnants of supernova explosions are composed of this quark matter. Because of the appearance of strange quarks, such objects are called strange stars. Considering their observational features, strange stars are very similar to neutron stars made of nucleonic matter, and therefore observations cannot exclude the existence of strange stars. This thesis introduces a new method for simulating mergers of compact stars and black holes within a general relativistic framework. The main goal of the present work is the investigation of the question, whether the coalescence of two strange stars in a binary system yields observational signatures that allow one to distinguish them from colliding neutron stars. In this context the gravitational-wave signals are analyzed. It is found that in general the characteristic frequencies in the gravitational-wave spectra are higher for strange stars. Moreover, the amount of matter that becomes gravitationally unbound during the merging is determined. The detection of ejecta of strange star mergers as potential component of cosmic ray flux could serve as a proof of the existence of strange quark matter. (orig.)

  5. Spherical configuration of a super-dense hot compact object with particular EoS

    CERN Document Server

    Tito, E P

    2016-01-01

    The equation of state (EoS) $P = P (\\rho, ...)$ -- pressure as a function of density and other thermodynamical quantities -- is what generates particularities of mass--radius distribution $M (R)$ for super--dense compact stellar bodies, the remnants of cosmic cataclysms. In view of recent nuclear experiments, we propose one particular EoS, which admits the critical state characterized by density $\\rho_c$ and temperature $T_c$, and which under certain conditions permits a radial distribution of the super--dense matter in "liquid" phase. We establish such conditions and demonstrate that a stable configuration is indeed possible (only) for temperatures smaller than the critical one. Using Tolman--Oppenheimer--Volkoff equations for hydrostatic equilibrium, we derive the mass--radius relation for the super--dense compact objects with masses smaller than the Sun, $M \\ll M_{\\odot}$. The obtained results are within the constraints established by both heavy--ion collision experiments and theoretical studies of neutron...

  6. Gravitational-wave radiation from double compact objects with eLISA in the Galaxy

    CERN Document Server

    Liu, Jinzhong

    2014-01-01

    The phase of in-spiral of double compact objects (DCOs: NS+WD, NS+NS, BH+NS, and BH+BH binaries) in the disk field population of the Galaxy provides a potential source in the frequency range from $10^{-4}$ to 0.1 Hz, which can be detected by the European New Gravitational Observatory (NGO: eLISA is derived from the previous LISA proposal) project. In this frequency range, much stronger gravitational wave (GW) radiation can be obtained from DCO sources because they possess more mass than other compact binaries (e.g., close double white dwarfs). In this study, we aim to calculate the gravitational wave signals from the resolvable DCO sources in the Galaxy using a binary population synthesis approach, and to carry out physical properties of these binaries using Monte Carlo simulations. Combining the sensitivity curve of the eLISA detector and a confusion-limited noise floor of close double white dwarfs, we find that only a handful of DCO sources can be detected by the eLISA detector. The detectable number of DCO...

  7. Relativistic simulations of compact object mergers for nucleonic matter and strange quark matter

    International Nuclear Information System (INIS)

    Under the assumption that the energy of the ground state of 3-flavor quark matter is lower than the one of nucleonic matter, the compact stellar remnants of supernova explosions are composed of this quark matter. Because of the appearance of strange quarks, such objects are called strange stars. Considering their observational features, strange stars are very similar to neutron stars made of nucleonic matter, and therefore observations cannot exclude the existence of strange stars. This thesis introduces a new method for simulating mergers of compact stars and black holes within a general relativistic framework. The main goal of the present work is the investigation of the question, whether the coalescence of two strange stars in a binary system yields observational signatures that allow one to distinguish them from colliding neutron stars. In this context the gravitational-wave signals are analyzed. It is found that in general the characteristic frequencies in the gravitational-wave spectra are higher for strange stars. Moreover, the amount of matter that becomes gravitationally unbound during the merging is determined. The detection of ejecta of strange star mergers as potential component of cosmic ray flux could serve as a proof of the existence of strange quark matter. (orig.)

  8. Kilonova Light Curves from the Disk Wind Outflows of Compact Object Mergers

    CERN Document Server

    Kasen, Daniel; Metzger, Brian

    2014-01-01

    We study the radioactively-powered transients produced by accretion disk winds following a compact object merger. Starting with the outflows generated in two-dimensional hydrodynamical disk models, we use wavelength-dependent radiative transfer calculations to generate synthetic light curves and spectra. We show that the brightness and color of the resulting kilonova transients carry information about the merger physics. In the regions of the wind where neutrino irradiation raises the electron fraction to Ye > 0.25, r-process nucleosynthesis halts before producing high-opacity, complex ions (the lanthanides). The kilonova light curves thus show two distinct components: a brief (~2 day) blue optical transient produced in the outer lanthanide-free ejecta, and a longer (~10 day) infrared transient produced in the inner, lanthanide line-blanketed region. Mergers producing a longer-lived neutron star, or a more rapidly spinning black hole, have stronger neutrino irradiation, generate more lanthanide-free ejecta, a...

  9. Von Zeipel's theorem for a magnetized circular flow around a compact object

    CERN Document Server

    Zanotti, O

    2014-01-01

    We analyze a class of physical properties, forming the content of the so-called von Zeipel theorem, which characterizes stationary, axisymmetric, non-selfgravitating perfect fluids in circular motion in the gravitational field of a compact object. We consider the extension of the theorem to the magnetohydrodynamic regime, under the assumption of an infinitely conductive fluid, both in the Newtonian and in the relativistic framework. When the magnetic field is toroidal, the conditions required by the theorem are equivalent to integrability conditions, as it is the case for purely hydrodynamic flows. When the magnetic field is poloidal, the analysis for the relativistic regime is substantially different with respect to the Newtonian case and additional constraints, in the form of PDEs, must be imposed on the magnetic field in order to guarantee that the angular velocity $\\Omega$ depends only on the specific angular momentum $\\ell$. In order to deduce such physical constraints, it is crucial to adopt special coo...

  10. A new direction for dark matter research: intermediate mass compact halo objects

    CERN Document Server

    Axelrod, T; Dawson, W; Frampton, P H

    2016-01-01

    The failure to find evidence for elementary particles that could serve as the constituents of dark matter brings to mind suggestions that dark matter might consist of massive compact objects (MACHOs). In particular, it has recently been argued that MACHOs with masses > 15 solar masses may have been prolifically produced at the onset of the big bang. Although a variety of astrophysical signatures for primordial MACHOs with masses in this range have been discussed in the literature, we favor a strategy that uses the potential for gravitational microlensing of stars outside our galaxy to directly detect the presence of MACHOs in the halo of our galaxy. We point out that the effect of the motion of the Earth on the shape of the microlensing brightening curves provides a promising approach to confirming over the course of next several years that dark matter consists of MACHOs.

  11. The importance of gravitational self field effects in binary systems with compact objects

    International Nuclear Information System (INIS)

    As a first step towards a proper treatment of compact objects in binary systems the attraction force of two massive bodies connected by a rod is calculated in a post-Newtonian expansion. Contrary to a calculation by H. Weyl und R. Bach we start without specializing the internal structure of the bodies. We consider general anisotropic pressures and also do not require axial symmetry for the bodies. We calculate the attraction force first in a post-Newtonian approximation and then (in paper II) we shall be concerned with the post-post-Newtonian approximation. In both approximations we obtain Newton's attraction force sup(M)S1sup(M)S2/R2 plus terms of order 1/R3 and higher, where Msub(S1), Msub(S2) are the Schwarzschild masses of the bodies. (orig.)

  12. Compact symmetric objects and supermassive binary black holes in the VLBA Imaging and Polarimetry Survey

    Science.gov (United States)

    Tremblay, S. E.; Taylor, G. B.; Ortiz, A. A.; Tremblay, C. D.; Helmboldt, J. F.; Romani, R. W.

    2016-06-01

    We present multifrequency Very Long Baseline Array (VLBA) follow-up observations of VLBA Imaging and Polarimetry Survey sources identified as likely compact symmetric objects (CSOs) or supermassive binary black holes (SBBHs). We also present new spectroscopic redshifts for 11 sources observed with the Hobby-Eberly Telescope. While no new SBBHs can be confirmed from these observations, we have identified 24 CSOs in the sample, 15 of which are newly designated, and refuted 52 candidates leaving 33 unconfirmed candidates. This is the first large uniform sample of CSOs which can be used to elicit some of the general properties of these sources, including morphological evolution and environmental interaction. We have detected polarized emission from two of these CSOs the properties of which are consistent with active galactic nuclei unification schemes.

  13. Compact Symmetric Objects and Supermassive Binary Black Holes in the VLBA Imaging and Polarimetry Survey

    CERN Document Server

    Tremblay, S E; Ortiz, A A; Tremblay, C D; Helmboldt, J F; Romani, R W

    2016-01-01

    We present multi-frequency Very Long Baseline Array (VLBA) follow-up observations of VLBA Imaging and Polarimetry Survey sources identified as likely compact symmetric objects (CSOs) or super-massive binary black holes (SBBHs). We also present new spectroscopic redshifts for 11 sources observed with the Hobby-Eberly Telescope. While no new SBBHs can be confirmed from these observations, we have identified 24 CSOs in the sample, 15 of which are newly designated, and refuted 52 candidates leaving 33 unconfirmed candidates. This is the first large uniform sample of CSOs which can be used to elicit some of the general properties of these sources, including morphological evolution and environmental interaction. We have detected polarised emission from two of these CSOs the properties of which are consistent with Active Galactic Nuclei unification schemes.

  14. Sound speeds, cracking and the stability of self-gravitating anisotropic compact objects

    International Nuclear Information System (INIS)

    Using the concept of cracking we explore the influence that density fluctuations and local anisotropy have on the stability of local and non-local anisotropic matter configurations in general relativity. This concept, conceived to describe the behavior of a fluid distribution just after its departure from equilibrium, provides an alternative approach to consider the stability of self-gravitating compact objects. We show that potentially unstable regions within a configuration can be identified as a function of the difference of propagations of sound along tangential and radial directions. In fact, it is found that these regions could occur when, at a particular point within the distribution, the tangential speed of sound is greater than the radial one

  15. Sound Speeds, Cracking and Stability of Self-Gravitating Anisotropic Compact Objects

    CERN Document Server

    Abreu, H; Núñez, L A

    2007-01-01

    Using the the concept of cracking we explore the influence of density fluctuations and local anisotropy have on the stability of local and non-local anisotropic matter configurations in general relativity. This concept, conceived to describe the behaviour of a fluid distribution just after its departure from equilibrium, provides an alternative approach to consider the stability of selfgravitating compact objects. We show that potentially unstable regions within a configuration can be identify as a function of the difference of propagations of sound along tangential and radial directions. In fact, it is found that these regions could occur when, at particular point within the distribution, the tangential speed of sound is greater than radial one.

  16. THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS

    International Nuclear Information System (INIS)

    We present a detailed investigation of Hubble Space Telescope rest-frame UV/optical observations of 22 short gamma-ray burst (GRB) host galaxies and sub-galactic environments. Utilizing the high angular resolution and depth of HST we characterize the host galaxy morphologies, measure precise projected physical and host-normalized offsets between the bursts and host centers, and calculate the locations of the bursts with respect to their host light distributions (rest-frame UV and optical). We calculate a median short GRB projected physical offset of 4.5 kpc, about 3.5 times larger than that for long GRBs, and find that ≈25% of short GRBs have offsets of ∼> 10 kpc. When compared to their host sizes, the median offset is 1.5 half-light radii (re ), about 1.5 times larger than the values for long GRBs, core-collapse supernovae, and Type Ia supernovae. In addition, ≈20% of short GRBs having offsets of ∼> 5re , and only ≈25% are located within 1re . We further find that short GRBs severely under-represent their hosts' rest-frame optical and UV light, with ≈30%-45% of the bursts located in regions of their host galaxies that have no detectable stellar light, and ≈55% in the regions with no UV light. Therefore, short GRBs do not occur in regions of star formation or even stellar mass. This demonstrates that the progenitor systems of short GRBs must migrate from their birth sites to their eventual explosion sites, a signature of kicks in compact object binary systems. Utilizing the full sample of offsets, we estimate natal kick velocities of ≈20-140 km s–1. These independent lines of evidence provide the strongest support to date that short GRBs result from the merger of compact object binaries (NS-NS/NS-BH)

  17. A Compact Dual-Band RFID Tag Antenna Mountable on Metallic Objects

    Directory of Open Access Journals (Sweden)

    Byeonggwi Mun

    2015-01-01

    Full Text Available A compact (50 × 50 × 4 mm3 dual-band radio frequency identification (RFID tag antenna mountable on metallic objects is proposed for the ultra-high frequency (UHF band (917∼923.5 MHz and the microwave (MW band (2.4∼2.45 GHz. With the proximity-coupled feed loop, the proposed antenna consists of two symmetric planar inverted-F antenna (PIFA elements for the UHF band passive tag and a meander microstrip patch antenna for the MW band active tag. The performance of the proposed antenna is verified by mounting it on the different sizes of the metallic object. Furthermore, the passive tag antenna in the UHF band furthermore may be used for energy harvesting techniques to improve the lifetime of the active tag in the MW band. The measured maximum read range is 5.50 m in the UHF band and 14.15 m in the MW band when the proposed tag antenna is mounted on the metallic objects. The total efficiency for all operating frequency bands is higher than 50%. High isolation (>12 dB between tag antennas in the UHF band and the MW band is achieved.

  18. Difficulties in explaining the cosmic photon excess with compact composite object dark matter

    Science.gov (United States)

    Cumberbatch, Daniel T.; Starkman, Glenn D.; Silk, Joseph

    2008-03-01

    It has been suggested that dark matter particles are strongly interacting, composite, macroscopically large objects made of well known light quarks (or antiquarks). In doing so it is argued that these compact composite objects (CCOs) provide natural explanations of observed data, such as the 511 keV line from the bulge of our galaxy observed by INTEGRAL, and the excess of diffuse gamma rays in the 1 20 MeV band observed by COMPTEL. Here we argue that the atmospheres of positrons that surround CCOs composed of di-antiquark pairs in the favored color-flavor-locked superconducting state are sufficiently dense as to place stringent limits on the penetration depth of interstellar electrons incident upon them, resulting in an extreme suppression of previously estimated rates of positronium formation, and hence in the flux of 511 keV photons resulting from their subsequent decays. The associated rate of direct electron-positron annihilations, which yield the MeV photons postulated to explain the 1 20 MeV photon excess, is also suppressed. We also discuss how even if a fraction of positrons somehow penetrated the surface of the CCOs, the extremely strong electric fields generated from the bulk antiquark matter would result in the destruction of positronium atoms long before they decay.

  19. Gravitational waves from spinning compact object binaries: New post-Newtonian results

    CERN Document Server

    Marsat, Sylvain; Bohe, Alejandro; Faye, Guillaume

    2013-01-01

    We report on recent results obtained in the post-Newtonian framework for the modelling of the gravitational waves emitted by binary systems of spinning compact objects (black holes and/or neutron stars). These new results are obtained at the spin-orbit (linear-in-spin) level and solving Einstein's field equations iteratively in harmonic coordinates as well as the multipolar post-Newtonian formalism. The dynamics of the binary was tackled at the next-to-next-to-leading order, corresponding to the 3.5 post-Newtonian (PN) order for maximally spinning objects, and the result is found to be consistent with a previously obtained reduced Hamiltonian in the ADM approach. The corresponding contribution to the energy flux emitted by the binary was obtained at the 3.5PN order, as well as the next-to-leading 4PN tail contribution to this flux, an imprint of the non-linearity in the propagation of the wave. These new terms can be used to build more accurate PN templates for the next generation of gravitational wave detect...

  20. Strain Distribution in Root Surface Dentin of Maxillary Central Incisors during Lateral Compaction

    Science.gov (United States)

    Pilo, Raphael; Metzger, Zvi; Brosh, Tamar

    2016-01-01

    Aim To precisely quantify the circumferential strains created along the radicular dentin of maxillary incisors during a simulated clinical procedure of lateral compaction. Methods Six miniature strain gauges were bonded on the roots of fourteen recently extracted maxillary central incisors that were subjected to root canal instrumentation. The strain gauges were bonded at three levels (apical, middle, and coronal) and four aspects (buccal, lingual, mesial, and distal) of the roots. Each tooth was embedded in a PVC cylinder containing polyvinyl-siloxane impression material. Root filling was then performed by simulating the clinical procedure of lateral compaction using nickel-titanium finger spreaders. The force applied to the spreader and the strains developing in the surface root dentin were continuously recorded at a frequency of 10 Hz. Results The highest strains that developed during lateral compaction were in the mesial and distal aspects at the apical level of the root. The magnitudes of the maximal mesial/distal strains at the apical as well as the mid-root levels were approximately 2.5–3 times higher than those at the buccal/lingual aspects (p = 0.041). The strains decreased significantly (pdentin but decrease gradually to negligible levels. PMID:27227404

  1. Objective Lightning Probability Forecasts for East-Central Florida Airports

    Science.gov (United States)

    Crawford, Winfred C.

    2013-01-01

    The forecasters at the National Weather Service in Melbourne, FL, (NWS MLB) identified a need to make more accurate lightning forecasts to help alleviate delays due to thunderstorms in the vicinity of several commercial airports in central Florida at which they are responsible for issuing terminal aerodrome forecasts. Such forecasts would also provide safer ground operations around terminals, and would be of value to Center Weather Service Units serving air traffic controllers in Florida. To improve the forecast, the AMU was tasked to develop an objective lightning probability forecast tool for the airports using data from the National Lightning Detection Network (NLDN). The resulting forecast tool is similar to that developed by the AMU to support space launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) for use by the 45th Weather Squadron (45 WS) in previous tasks (Lambert and Wheeler 2005, Lambert 2007). The lightning probability forecasts are valid for the time periods and areas needed by the NWS MLB forecasters in the warm season months, defined in this task as May-September.

  2. Study of the high energy emission of accreting compact objects with SPI/INTEGRAL

    International Nuclear Information System (INIS)

    The study of the high energy emission is essential for understanding the radiative processes inherent to accretion flows onto compact objects (black holes and neutron stars). The X/γ-ray continuum of these systems is successfully interpreted in terms of two components. The first component corresponds to blackbody emission from a geometrically thin optically thick accretion disk while the second component is generally associated to Compton scattering of the thermal disk flux off hot electrons. Despite considerable advances throughout the years, the heating mechanisms as well as the structure of the hot Comptonizing plasma remain poorly understood. In order to shed light on the physical processes that govern the innermost regions of the accretion flow, we take advantage of the data archive accumulated by the SPI instrument, a high energy spectrometer (20 keV - 8 MeV) developed at the CESR (now IRAP, Toulouse, France) for the INTEGRAL mission. Above 150 keV, SPI combines a unique spectral resolution with unequalled sensitivity, being thus an ideal tool to study the high energy emission of accreting compact objects. The thesis manuscript reports on the results of timing and spectral studies of three particular systems. First, I address the high energy emission of the enigmatic micro-quasar GRS 1915+105, a source characterized by colossal luminosity and strong chaotic variability in X-rays. On a timescale of about one day, the photon index of the 20 - 200 keV spectrum varies between 2.7 and 3.5; at higher energies (≥150 keV), SPI unveils the systematic presence of an additional emission component, extending without folding energy up to ∼ 500 keV. Second, I study the high energy emission of GX 339-4, a source whose spectral properties are representative of black hole transients. The spectrum of the luminous hard state of this system shows a variable high energy tail (≥150 keV), with significant flux changes on a short timescale (several hours). I explain the

  3. Strain Distribution in Root Surface Dentin of Maxillary Central Incisors during Lateral Compaction.

    Directory of Open Access Journals (Sweden)

    Raphael Pilo

    Full Text Available To precisely quantify the circumferential strains created along the radicular dentin of maxillary incisors during a simulated clinical procedure of lateral compaction.Six miniature strain gauges were bonded on the roots of fourteen recently extracted maxillary central incisors that were subjected to root canal instrumentation. The strain gauges were bonded at three levels (apical, middle, and coronal and four aspects (buccal, lingual, mesial, and distal of the roots. Each tooth was embedded in a PVC cylinder containing polyvinyl-siloxane impression material. Root filling was then performed by simulating the clinical procedure of lateral compaction using nickel-titanium finger spreaders. The force applied to the spreader and the strains developing in the surface root dentin were continuously recorded at a frequency of 10 Hz.The highest strains that developed during lateral compaction were in the mesial and distal aspects at the apical level of the root. The magnitudes of the maximal mesial/distal strains at the apical as well as the mid-root levels were approximately 2.5-3 times higher than those at the buccal/lingual aspects (p = 0.041. The strains decreased significantly (p<0.04 from the apical through the mid-root levels to the coronal level, yielding gradients of 2.5- and 6-fold, respectively. The mesial and distal strains were consistently tensile and did not differ significantly; however, the buccal strains were generally 35-65% higher than the lingual strains (p = 0.078. Lateral compaction resulted in the gradual build-up of residual strains, resulting in generation of a 'stair-step' curve. These strains declined gradually and almost completely disappeared after 1000 sec.With proper mounting of several miniature strain gauges at various levels and aspects of the root, significant circumferential strains can be monitored under clinically relevant compaction forces. The residual strains at the end of lateral compaction are not stored in the

  4. Von Zeipel's theorem for a magnetized circular flow around a compact object

    Science.gov (United States)

    Zanotti, O.; Pugliese, D.

    2015-04-01

    We analyze a class of physical properties, forming the content of the so-called von Zeipel theorem, which characterizes stationary, axisymmetric, non-selfgravitating perfect fluids in circular motion in the gravitational field of a compact object. We consider the extension of the theorem to the magnetohydrodynamic regime, under the assumption of an infinitely conductive fluid, both in the Newtonian and in the relativistic framework. When the magnetic field is toroidal, the conditions required by the theorem are equivalent to integrability conditions, as it is the case for purely hydrodynamic flows. When the magnetic field is poloidal, the analysis for the relativistic regime is substantially different with respect to the Newtonian case and additional constraints, in the form of PDEs, must be imposed on the magnetic field in order to guarantee that the angular velocity depends only on the specific angular momentum . In order to deduce such physical constraints, it is crucial to adopt special coordinates, which are adapted to the surfaces. The physical significance of these results is briefly discussed.

  5. Filamentary structures and compact objects in the Aquila and Polaris clouds observed by Herschel

    CERN Document Server

    Men'shchikov, A; Didelon, P; Könyves, V; Schneider, N; Motte, F; Bontemps, S; Arzoumanian, D; Attard, M; Abergel, A; Baluteau, J -P; Bernard, J -Ph; Cambrésy, L; Cox, P; Di Francesco, J; di Giorgio, A M; Griffin, M; Hargrave, P; Huang, M; Kirk, J; Li, J Z; Martin, P; Minier, V; Miville-Deschênes, M -A; Molinari, S; Olofsson, G; Pezzuto, S; Roussel, H; Russeil, D; Saraceno, P; Sauvage, M; Sibthorpe, B; Spinoglio, L; Testi, L; Ward-Thompson, D; White, G; Wilson, C D; Woodcraft, A; Zavagno, A

    2010-01-01

    Our PACS and SPIRE images of the Aquila Rift and part of the Polaris Flare regions, taken during the science demonstration phase of Herschel discovered fascinating, omnipresent filamentary structures that appear to be physically related to compact cores. We briefly describe a new multi-scale, multi-wavelength source extraction method used to detect objects and measure their parameters in our Herschel images. All of the extracted starless cores (541 in Aquila and 302 in Polaris) appear to form in the long and very narrow filaments. With its combination of the far-IR resolution and sensitivity, Herschel directly reveals the filaments in which the dense cores are embedded; the filaments are resolved and have deconvolved widths of 35 arcsec in Aquila and 59 arcsec in Polaris (9000 AU in both regions). Our first results of observations with Herschel enable us to suggest that in general dense cores may originate in a process of fragmentation of complex networks of long, thin filaments, likely formed as a result of ...

  6. General relativistic hydrodynamic flows around a static compact object in final stages of accretion flow

    Directory of Open Access Journals (Sweden)

    J Ghanbari

    2009-12-01

    Full Text Available Dynamics of stationary axisymmetric configuration of the viscous accreting fluids surrounding a non-rotating compact object in final stages of accretion flow is presented here. For the special case of thin disk approximation, the relativistic fluid equations ignoring self-gravity of the disk are derived in Schwarzschild geometry. For two different state equations, two sets of self-consistent analytical solutions of fully relativistic fluid equations are obtained separately. The effect of bulk viscosity coefficient on the physical functions are investigated for each state equation, as well as the bounds that exert on the free parameters due to the condition of accretion flow in the last stages. The solutions found show that the radial and azimuthal velocities, density and pressure of the fluid increase inwards for both state equations. Also, viscosity has no effect on the velocities and density distributions in both state equations. Two state equations show different types of behavior with respect to the bulk viscosity coefficient. For p=K state equation, if there is no bulk viscosity, the pressure remains constant throughout the disk, whereas with increasing bulk viscosity the pressure falls off in the inner regions but soon stabilizes at an almost constant value. However, for p=ρc2 state equation, the pressure is never constant, even in the absence of bulk viscosity. The larger the value of ηb, the higher the value of pressure in the inner regions.

  7. What can QPOs tell us about the structure of the corresponding compact objects?

    CERN Document Server

    Pappas, George

    2012-01-01

    We show how one can estimate the multipole moments of the space-time, assuming that the quasi-periodic modulations of the X-ray flux (QPOs), observed from accreting neutron stars or black holes, are due to orbital and precession frequencies (relativistic precession model). The precession frequencies $\\Omega_{\\rho}$ and $\\Omega_z$ can be expressed as expansions on the orbital frequency $\\Omega$, in which the moments enter the coefficients in a prescribed form. Thus observations can be fitted to these expression to evaluate the moments. If the compact object is a neutron star, constrains can be imposed on the equation of state. The same analysis can be used for black holes as a test for the validity of the no-hair theorem. Alternatively, instead of fitting for the moments, observations can be matched to frequencies calculated from analytic models that are produced so as to correspond to realistic neutron stars described by various equations of state. Observations can thus be used to constrain the equation of st...

  8. Detecting Sub-lunar Mass Compact Objects toward the Local Group Galaxies

    CERN Document Server

    Inoue, Kaiki Taro

    2016-01-01

    By monitoring a large number of stars in the Local Group galaxies such as M33 with an 8\\,m-class telescope with time integration of $\\sim 100\\,$sec per shot, we can detect microlensing events by sub-lunar mass compact objects (SULCOs) such as primordial black holes (PBHs) and rogue (free-floating) dwarf planets. For one night observation, we would be able to detect $10^{3-4}$ microlensing events caused by SULCOs with a mass of $10^{-9}$ to $10^{-7}$ solar mass for sources with S/N$>5$ if SULCOs constitute all the dark matter components. Moreover, we expect $10^{1-2}$ events in which sources with S/N$>100$ are weakly amplified due to lensing by SULCOs with a mass range of $10^{-11}$ to $10^{-7}$ solar mass. The method would provide a stringent constraint on the abundance of SULCOs at the distance $0.1-100$ kpc from us.

  9. WHAT IS ON TAP? THE ROLE OF SPIN IN COMPACT OBJECTS AND RELATIVISTIC JETS

    International Nuclear Information System (INIS)

    We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3σ confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3σ confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4σ and 4.1σ confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log (νLR/LBol0.67/MBH0.78)) and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e., bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the ''throttle'' in these compact systems, to which the

  10. ISO observations of Hickson Compact Group 31 with the central Wolf-Rayet galaxy NGC 1741

    CERN Document Server

    O'Halloran, B; McBreen, B; Laureijs, R J; Leech, K; Delaney, M; Watson, D; Hanlon, L O

    2002-01-01

    Hickson Compact Group (HCG) 31, consisting of the Wolf-Rayet galaxy NGC 1741 and its irregular dwarf companions, was observed using the Infrared Space Observatory. The deconvolved ISOCAM maps of the galaxies using the 7.7 micron and 14.3 micron (LW6 and LW3) filters are presented, along with ISOPHOT spectrometry of the central starburst region of NGC 1741 and the nucleus of galaxy HCG 31A. Strong mid-IR emission was detected from the central burst in NGC 1741, along with strong PAH features and a blend of features including [S IV] at 10.5 micron. The 14.3/6.75 micron flux ratio, where the 6.75 micron flux was synthesized from the PHT-S spectrum, and 14.3/7.7 micron flux ratios suggest that the central burst within NGC 1741 may be moving towards the post-starburst phase. Diagnostic tools including the ratio of the integrated PAH luminosity to the 40 to 120 micron infrared luminosity and the far-infrared colours reveal that despite the high surface brightness of the nucleus, the properties of NGC 1741 can be ex...

  11. Compact Planetary Nebulae in the Galactic Disk: Analysis of the Central Stars

    CERN Document Server

    Moreno-Ibáñez, Manuel; Shaw, Richard A; Stanghellini, Letizia

    2016-01-01

    We have obtained multi-wavelength observations of compact Galactic planetary nebulae (PNe) to probe post-Asymptotic Giant Branch (AGB) evolution from the onset of nebular ejection. We analyze new observations from HST to derive the masses and evolutionary status of their central stars (CSs) in order to better understand the relationship between the CS properties and those of the surrounding nebulae. We also compare this sample with others we obtained using the same technique in different metallicity environments: the Large and Small Magellanic Clouds. We work with HST/WFC3 images of 51 targets obtained in a snapshot survey (GO-11657). The high spatial resolution of HST allows us to resolve these compact PNe and distinguish the CS emission from that of their surrounding PNe. The targets were imaged through the filters F200LP, F350LP, and F814W from which we derive Johnson V and I magnitudes. We derive CS bolometric luminosities and effective temperatures using the Zanstra technique, from a combination of HST p...

  12. SPITZER MID-INFRARED SPECTROSCOPY OF COMPACT SYMMETRIC OBJECTS: WHAT POWERS RADIO-LOUD ACTIVE GALACTIC NUCLEI?

    International Nuclear Information System (INIS)

    We present low- and high-resolution mid-infrared (mid-IR) spectra and photometry for eight compact symmetric objects (CSOs) taken with the Infrared Spectrograph on the Spitzer Space Telescope. The hosts of these young, powerful radio galaxies show significant diversity in their mid-IR spectra. This includes multiple atomic fine-structure lines, H2 gas, polycyclic aromatic hydrocarbon (PAH) emission, warm dust from T = 50to150 K, and silicate features in both emission and absorption. There is no evidence in the mid-IR of a single template for CSO hosts, but 5/8 galaxies show similar moderate levels of star formation (sun yr-1 from PAH emission) and silicate dust in a clumpy torus. The total amount of extinction ranges from AV ∼ 10to30, and the high-ionization [Ne V] 14.3 and 24.3 μm transitions are not detected for any galaxy in the sample. Almost all CSOs show contributions both from star formation and active galactic nuclei (AGNs), suggesting that they occupy a continuum between pure starbursts and AGNs. This is consistent with the hypothesis that radio galaxies are created following a galactic merger; the timing of the radio activity onset means that contributions to the IR luminosity from both merger-induced star formation and the central AGN are likely. Bondi accretion is capable of powering the radio jets for almost all CSOs in the sample; the lack of [Ne V] emission suggests an advection-dominated accretion flow mode as a possible candidate. Merging black holes (BHs) with MBH > 108 Msun likely exist in all of the CSOs in the sample; however, there is no direct evidence from these data that BH spin energy is being tapped as an alternative mode for powering the radio jets.

  13. Echoes of ECOs: gravitational-wave signatures of exotic compact objects and of quantum corrections at the horizon scale

    CERN Document Server

    Cardoso, Vitor; Macedo, Caio F B; Palenzuela, Carlos; Pani, Paolo

    2016-01-01

    Gravitational waves from binary coalescences provide one of the cleanest signatures of the nature of compact objects. It has been recently argued that the post-merger ringdown waveform of exotic ultracompact objects is initially identical to that of a black-hole, and that putative corrections at the horizon scale will appear as secondary pulses after the main burst of radiation. Here we extend this analysis in three important directions: (i)~we show that this result applies to a large class of exotic compact objects with a photon sphere for generic orbits in the test-particle limit; (ii)~we investigate the late-time ringdown in more detail, showing that it is universally characterized by a modulated and distorted train of "echoes" of the modes of vibration associated with the photon sphere; (iii)~we study for the first time equal-mass, head-on collisions of two ultracompact boson stars and compare their gravitational-wave signal to that produced by a pair of black-holes. If the initial objects are compact eno...

  14. Quantized gravitational waves and a novel dark energy-like quantum effect from DArk Compact Halo Objects (DACHOs)

    OpenAIRE

    Chavda, Abhijit; Chavda, L.,

    2016-01-01

    If dark matter consists of stable, nonrelativistic, purely gravitating subatomic particles, then inhomogeneities in its distributions such as galactic halos should lead to the formation of macro-scopic, classical-scale quantum bound states of these particles. Depending on the constituent particles' masses and their quantum configuration, these DArk Compact Halo Objects (DACHOs) emit quantized gravitational radiation over a wide range of frequencies, including the Advanced LIGO range, making g...

  15. Fundamental fields around compact objects: Massive spin-2 fields, Superradiant instabilities and Stars with dark matter cores

    OpenAIRE

    Brito, Richard

    2016-01-01

    Fundamental bosonic fields of arbitrary spin are predicted by generic extensions of the Standard Model and of General Relativity, and are well-motivated candidates to explain the dark components of the Universe. One of most promising channels to look for their presence is through their gravitational interaction with compact objects. Within this context, in this thesis I study several mechanisms by which bosonic fields may affect the dynamics and structure of black holes and neutron stars. The...

  16. Soil compaction of various Central European forest soils caused by traffic of forestry machines with various chassis

    Directory of Open Access Journals (Sweden)

    Michal Allman

    2015-12-01

    Full Text Available Aim of study: The primary objective of this paper was to compare the effects of different types of forestry machine chassis on the compaction of the top layers of soil and to define the soil moisture content level, at which machine traffic results in maximum compaction.Area of study: Measurements were conducted in eight forest stands located in Slovakia and the Czech Republic. The soil types in the stands subjected to the study were luvisols, stagnosols, cambisols, and rendzinas.Material and Methods: The measurements were focused on tracked and wheeled (equipped with low pressure tyres cut-to-length machines, and skidders equipped with wide and standard tyres. The bulk density of soil was determined from soil samples extracted from the ruts, the centre of the skid trail, and the undisturbed stand. To determine soil moisture content, at which the soil is the most susceptible to compaction, the Proctor standard test was employed.Main results: The moisture content for maximal compaction fluctuated from 12% to 34.06%. Wheeled machines compacted the soil to 1.24 – 1.36 g.cm-3 (30.3 – 35.4 % compaction in dried state. Bulk density of soil in stands where tracked machine operated was lower, ranging from 1.02 to 1.06 g.cm-3 (25.3 % compaction.Research highlights: All wheeled machines caused the same amount of soil compaction in the ruts, despite differences in tyres, machine weight, etc. Maximum compaction caused by forestry machines occurred at minimal moisture contents, easily achievable in European climatic conditions.  Keywords: soil compaction; bulk density; soil moisture content limits; cut-to-length machines; skidders.

  17. Discussion paper: siting a low-level radioactive waste disposal facility in the Central Interstate Low-Level Radioactive Waste Compact region. A model for other regions

    International Nuclear Information System (INIS)

    While this paper is intended to be broad enough in scope to cover the concerns and implementation guidelines of any compact commission, the focus will be on the procedures and guidelines that must be followed under the terms of the Central Interstate Low-Level Radioactive Waste Compact. This is not necessarily an endorsement of the Central States Compact approach to siting but is rather an attempt to discuss the siting process by using an existing compact as an example. As stated earlier, each compact commission will have to follow the specific guidelines of its compact. Many of the procedures to be followed and technical standards to be considered, however, apply to all the compacts

  18. Compact object mergers: Observations of supermassive binary black holes and stellar tidal disruption events

    CERN Document Server

    Komossa, S

    2015-01-01

    The capture and disruption of stars by supermassive black holes (SMBHs), and the formation and coalescence of binaries, are inevitable consequences of the presence of SMBHs at the cores of galaxies. Pairs of active galactic nuclei (AGN) and binary SMBHs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. In the early and advanced stages of galaxy merging, observations of the triggering of accretion onto one or both BHs inform us about feedback processes and BH growth. Identification of the compact binary SMBHs at parsec and sub-parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the "final parsec". Coalescing binary SMBHs are among the most powerful sources of gravitational waves (GWs) in the universe. Stellar tidal disruption events (TDEs) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the SMBH. About 30 events have b...

  19. Evolution of low-mass X-ray binaries: dependence on the mass of the compact object

    Institute of Scientific and Technical Information of China (English)

    Qian Xu; Tao Li; Xiang-Dong Li

    2012-01-01

    We perform numerical calculations to simulate the evolution of low-mass X-ray binary systems.For the accreting compact object we consider the initial mass of 1.4,10,20,100,200,500 and 1000 M☉,corresponding to neutron stars (NSs),stellarmass black holes (BHs) and intermediate-mass BHs.Mass transfer in these binaries is driven by nuclear evolution of the donors and/or orbital angular momentum loss due to magnetic braking and gravitational wave radiation.For the different systems,we determine their bifurcation periods Pbif that separate the formation of converging systems from the diverging ones,and show that Pbif changes from ~ 1 d to (≥)3 d for a 1 M☉ donor star,with increasing initial accretor mass from 1.4 to 1000 M☉.This means that the dominant mechanism of orbital angular momentum loss changes from magnetic braking to gravitational radiation.As an illustration we compare the evolution of binaries consisting of a secondary star of 1 M☉ at a fixed initial period of 2 d.In the case of the NS or stellar-mass BH accretor,the system evolves to a well-detached He white dwarf-neutron star/black hole pair,but it evolves to an ultracompact binary if the compact object is an intermediate-mass BH.Thus the binary evolution heavily depends upon the mass of the compact object.However,we show that the final orbital period-white dwarf mass relation found for NS low-mass X-ray binaries is fairly insensitive to the initial mass of the accreting star,even if it is an intermediate-mass BH.

  20. Spectroscopy of the short-hard GRB 130603B. The host galaxy and environment of a compact object merger

    Science.gov (United States)

    de Ugarte Postigo, A.; Thöne, C. C.; Rowlinson, A.; García-Benito, R.; Levan, A. J.; Gorosabel, J.; Goldoni, P.; Schulze, S.; Zafar, T.; Wiersema, K.; Sánchez-Ramírez, R.; Melandri, A.; D'Avanzo, P.; Oates, S.; D'Elia, V.; De Pasquale, M.; Krühler, T.; van der Horst, A. J.; Xu, D.; Watson, D.; Piranomonte, S.; Vergani, S. D.; Milvang-Jensen, B.; Kaper, L.; Malesani, D.; Fynbo, J. P. U.; Cano, Z.; Covino, S.; Flores, H.; Greiss, S.; Hammer, F.; Hartoog, O. E.; Hellmich, S.; Heuser, C.; Hjorth, J.; Jakobsson, P.; Mottola, S.; Sparre, M.; Sollerman, J.; Tagliaferri, G.; Tanvir, N. R.; Vestergaard, M.; Wijers, R. A. M. J.

    2014-03-01

    Context. Short duration gamma-ray bursts (SGRBs) are thought to be related to the violent merger of compact objects, such as neutron stars or black holes, which makes them promising sources of gravitational waves. The detection of a "kilonova"-likesignature associated to the Swift-detected GRB 130603B has suggested that this event is the result of a compact object merger. Aims: Our knowledge on SGRB has been, until now, mostly based on the absence of supernova signatures and the analysis of the host galaxies to which they cannot always be securely associated. Further progress has been significantly hampered by the faintness and rapid fading of their optical counterparts (afterglows), which has so far precluded spectroscopy of such events. Afterglow spectroscopy is the key tool to firmly determine the distance at which the burst was produced, crucial to understand its physics, and study its local environment. Methods: Here we present the first spectra of a prototypical SGRB afterglow in which both absorption and emission features are clearly detected. Together with multi-wavelength photometry we study the host and environment of GRB 130603B. Results: From these spectra we determine the redshift of the burst to be z = 0.3565 ± 0.0002, measure rich dynamics both in absorption and emission, and a substantial line of sight extinction of AV = 0.86 ± 0.15 mag. The GRB was located at the edge of a disrupted arm of a moderately star forming galaxy with near-solar metallicity. Unlike for most long GRBs (LGRBs), NHX/AV is consistent with the Galactic ratio, indicating that the explosion site differs from those found in LGRBs. Conclusions: The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the compact object binary. Appendices are available in electronic form at http://www.aanda.org

  1. Micro - tidal disruption events by stellar compact objects and the production of ultra-long GRBs/XRFs

    CERN Document Server

    Perets, Hagai B; Lombardi, James C; Milcarek, Stephen R

    2016-01-01

    We investigate the possibility of full and partial tidal disruption events (TDEs) of stars/planets by stellar compact objects (Black holes; BHs; or neutron stars; NSs), which we term micro-TDEs. Disruption of an object with mass M_* may lead to the formation of a debris disk around the compact object. The accretion of the debris may then give rise to energetic and long (10^3-10^4 s), X-ray/Gamma ray flares, with total energies of up to 10^52 ergs, possibly resembling the isotropic equivalent energy of ultra-long GRBs or XRFs. The energy of such accretion flares depends on the poorly constrained accretion processes. It is possible that most of the mass in the accretion disk would be blown away through strong outflows, leaving only a small fraction (<10^(-4)) of the mass to be accreted, thereby producing faint flares; brighter flares are produced in more acrretion-efficient scenarios. We suggest three dynamical origins for such disruptions. In the first, a star/planet is tidally disrupted following a close r...

  2. Off-equatorial orbits in strong gravitational fields near compact objects

    International Nuclear Information System (INIS)

    Near a black hole or an ultracompact star, the motion of particles is governed by a strong gravitational field. Electrically charged particles also feel the electromagnetic force arising due to currents inside the star or plasma circling around. We study the possibility that the interplay between gravitational and electromagnetic actions may allow for the stable, energetically bound off-equatorial motion of charged particles. This would represent the well-known generalized Stoermer's 'halo orbits', which have been discussed in connection with the motion of dust grains in planetary magnetospheres. We demonstrate that such orbits exist and can be astrophysically relevant when a compact star or a black hole is endowed with a dipole-type magnetic field. In the case of the Kerr-Newman solution, numerical analysis shows that the mutually connected gravitational and electromagnetic fields do not allow the existence of stable halo orbits above the outer horizon of black holes. Such orbits are either hidden under the inner black-hole horizon, or they require the presence of a naked singularity

  3. X-ray Observations of Disrupted Recycled Pulsars: No Refuge for Orphaned Central Compact Objects

    CERN Document Server

    Gotthelf, E V; Allen, B; Knispel, B

    2013-01-01

    We present a Chandra X-ray survey of the disrupted recycled pulsars (DRPs), isolated radio pulsars with P > 20 ms and B_s 1E4 - 1E5 yr, roughly 10 times the ages of the approximately 10 known CCOs in a similar volume of the Galaxy. The order of a hundred CCO descendants that could be detected by this method are thus either intrinsically radio quiet, or occupy a different region of (P,B_s) parameter space from the DRPs. This motivates a new X-ray search for orphaned CCOs among radio pulsars with larger B-fields, which could verify the theory that their fields are buried by fall-back of supernova ejecta, but quickly regrow to join the normal pulsar population.

  4. Stable Levitation and Alignment of Compact Objects by Casimir Spring Forces

    International Nuclear Information System (INIS)

    We investigate a stable Casimir force configuration consisting of an object contained inside a spherical or spheroidal cavity filled with a dielectric medium. The spring constant for displacements from the center of the cavity and the dependence of the energy on the relative orientations of the inner object and the cavity walls are computed. We find that the stability of the force equilibrium--unlike the direction of the torque--can be predicted based on the sign of the force between two slabs of the same material.

  5. Stability Bounds on Compact Astrophysical Objects from Information-Entropic Measure

    OpenAIRE

    Gleiser, Marcelo; Jiang, Nan

    2015-01-01

    We obtain bounds on the stability of various self-gravitating astrophysical objects using a new measure of shape complexity known as configurational entropy. We apply the method to Newtonian polytropes, neutron stars with an Oppenheimer-Volkoff equation of state, and to self-gravitating configurations of complex scalar field (boson stars) with different self-couplings, showing that the critical stability region of these stellar configurations obtained from traditional perturbation methods cor...

  6. Host Galaxies, Obscuration and Nuclear Structure of Three Nearby Compact Symmetric Objects

    CERN Document Server

    Perlman, E S; Conway, J; Reynolds, C; Perlman, Eric S.; Stocke, John T.; Conway, John; Reynolds, Christopher S

    2001-01-01

    We present 3-band HST imaging of three z/= 10^8 years ago. Such a merger could have "triggered" the current activity in these objects, but our data require a significant time delay between the merger and the onset of nuclear activity. However, these data are also consistent with the hypothesis that the onset of nuclear activity in radio galaxies is due to relatively minor "feeding" events and/or the formation of "bars within bars", which would disturb the internal kinematics only slightly.

  7. Stability Bounds on Compact Astrophysical Objects from Information-Entropic Measure

    CERN Document Server

    Gleiser, Marcelo

    2015-01-01

    We obtain bounds on the stability of various self-gravitating astrophysical objects using a new measure of shape complexity known as configurational entropy. We apply the method to Newtonian polytropes, neutron stars with an Oppenheimer-Volkoff equation of state, and to self-gravitating configurations of complex scalar field (boson stars) with different self-couplings, showing that the critical stability region of these stellar configurations obtained from traditional perturbation methods correlates well with critical points of the configurational entropy with accuracy of a few percent or better.

  8. Non-linear effects on radiation propagation around a charged compact object

    CERN Document Server

    Cuzinatto, R R; de Vasconcelos, K C; Medeiros, L G; Pompeia, P J

    2015-01-01

    The propagation of non-linear electromagnetic waves is carefully analyzed on a curved spacetime created by static spherically symmetric mass and charge distribution. We compute how the non-linear electrodynamics affects the geodesic deviation and the redshift of photons propagating near this massive charged object and, in the linear approximation, the effects of electromagnetic self-interaction can be disparted from the usual Reissner-Nordstr\\"om terms. In the particular case of Euler-Heisenberg effective Lagrangian, we find that these self-interaction effects might be important near charged white dwarfs.

  9. Location of 24 extensometers used to measure compaction in the Central Valley

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset describes the location of 21 extensometers used for observations of subsidence in the Central Valley Hydrologic Model (CVHM). The Central...

  10. Galactic microlensing as a method of detecting massive compact halo objects

    International Nuclear Information System (INIS)

    The dark matter of the Galaxy may well consist of Jupiters, brown dwarfs, or the remnants of an early generation of stars. In 1986, Paczynski suggested that a population of such objects could be detected by watching for microlensing of stars in the LMC. Using a more realistic model of the halo density and velocity structure this paper recalculates the microlensing optical depth, the microlensing event rate, and the average duration of an event, correcting an error, but finding rough agreement with Paczynski's estimates. Also calculated is the distribution of microlensing events as a function of their duration and amplitude, finding that photometric measurements more frequent than the average event duration are needed to detect a substantial fraction of the events. 24 refs

  11. Radioactivity and thermalization in the ejecta of compact object mergers and their impact on kilonova light curves

    CERN Document Server

    Barnes, Jennifer; Wu, Meng-Ru; Mart'inez-Pinedo, Gabriel

    2016-01-01

    One of the most promising electromagnetic signatures of compact object mergers are kilonovae: approximately isotropic radioactively-powered transients that peak days to weeks post-merger. Key uncertainties in modeling kilonovae include the emission profiles of the radioactive decay products---non-thermal beta- and alpha-particles, fission fragments, and gamma-rays---and the efficiency with which they deposit their energy in the ejecta. The total radioactive energy and the efficiency of its thermalization sets the luminosity budget and is therefore necessary for predicting kilonova light curves. We outline the uncertainties in r-process decay, describe the physical processes by which the energy of the decay products is absorbed in the ejecta, and present time-dependent thermalization efficiencies for each particle type. We determine the net heating efficiency and explore its dependence on r-process yields---in particular, the production of translead nuclei that undergo alpha-decay---and on the ejecta's mass, v...

  12. X-ray Astronomy in the Laboratory with a Miniature Compact Object Produced by Laser-Driven Implosion

    CERN Document Server

    Fujioka, Shinsuke; Yamamoto, Norimasa; Salzmann, David; Wang, Feilu; Nishimura, Hiroaki; Li, Yutong; Dong, Quanli; Wang, Shoujun; Zhang, Yi; Rhee, Yong-Joo; Lee, Yong-Woo; Han, Jae-Min; Tanabe, Minoru; Fujiwara, Takashi; Nakabayashi, Yuto; Zhao, Gang; Zhang, Jie; Mima, Kunioki

    2009-01-01

    Laboratory spectroscopy of non-thermal equilibrium plasmas photoionized by intense radiation is a key to understanding compact objects, such as black holes, based on astronomical observations. This paper describes an experiment to study photoionizing plasmas in laboratory under well-defined and genuine conditions. Photoionized plasma is here generated using a 0.5-keV Planckian x-ray source created by means of a laser-driven implosion. The measured x-ray spectrum from the photoionized silicon plasma resembles those observed from the binary stars Cygnus X-3 and Vela X-1 with the Chandra x-ray satellite. This demonstrates that an extreme radiation field was produced in the laboratory, however, the theoretical interpretation of the laboratory spectrum significantly contradicts the generally accepted explanations in x-ray astronomy. This model experiment offers a novel test bed for validation and verification of computational codes used in x-ray astronomy.

  13. Discovery of new objects in the Orion nebula on HST images - Shocks, compact sources, and protoplanetary disks

    Science.gov (United States)

    O'Dell, C. R.; Wen, Zheng; Hu, Xihai

    1993-01-01

    We have reduced and analyzed a set of narrow-band HST images of a portion of M42 south of the Trapezium. Many new emission-line sources were found, some quite long but so narrow that they are not seen on ground-based images. These include thin shells which are high-ionization shocks. The structure around Orion HH 3 is resolved into multiple components. Slit spectroscopy data establish the high expansion velocities of all these regions. The other objects seen are compact sources. Although some had been detected in VLA surveys and several had been seen from the ground optically, the new images show previously undetected structure and clearly establish that most are protoplanetary disks, which are neutral disks surrounding low-mass pre-main-sequence stars and are ionized from the outside by Theta sup 1 C and Theta sup 2 A Ori.

  14. A RAY-TRACING ALGORITHM FOR SPINNING COMPACT OBJECT SPACETIMES WITH ARBITRARY QUADRUPOLE MOMENTS. I. QUASI-KERR BLACK HOLES

    International Nuclear Information System (INIS)

    We describe a new numerical algorithm for ray tracing in the external spacetimes of spinning compact objects characterized by arbitrary quadrupole moments. Such spacetimes describe non-Kerr vacuum solutions that can be used to test the no-hair theorem in conjunction with observations of accreting black holes. They are also appropriate for neutron stars with spin frequencies in the ≅ 300-600 Hz range, which are typical of the bursting sources in low-mass X-ray binaries. We use our algorithm to show that allowing for the quadrupole moment of the spacetime to take arbitrary values leads to observable effects in the profiles of relativistic broadened fluorescent iron lines from geometrically thin accretion disks.

  15. Formalism for testing theories of gravity using lensing by compact objects. II. Probing post-post-Newtonian metrics

    International Nuclear Information System (INIS)

    We study gravitational lensing by compact objects in gravity theories that can be written in a post-post-Newtonian (PPN) framework: i.e., the metric is static and spherically symmetric, and can be written as a Taylor series in m /r, where m is the gravitational radius of the compact object. Working invariantly, we compute corrections to standard weak-deflection lensing observables at first and second order in the perturbation parameter ε=θ/θE, where θ is the angular gravitational radius and θE is the angular Einstein ring radius of the lens. We show that the first-order corrections to the total magnification and centroid position vanish universally for gravity theories that can be written in the PPN framework. This arises from some surprising, fundamental relations among the lensing observables in PPN gravity models. We derive these relations for the image positions, magnifications, and time delays. A deep consequence is that any violation of the universal relations would signal the need for a gravity model outside the PPN framework (provided that some basic assumptions hold). In practical terms, the relations will guide observational programs to test general relativity, modified gravity theories, and possibly the cosmic censorship conjecture. We use the new relations to identify lensing observables that are accessible to current or near-future technology, and to find combinations of observables that are most useful for probing the spacetime metric. We give explicit applications to the galactic black hole, microlensing, and the binary pulsar J0737-3039

  16. Central interstate low-level radioactive waste compact region site exclusionary screening study. Phase I. Final report

    International Nuclear Information System (INIS)

    The Low-Level Radioactive Waste Policy Act of 1980 assigns to the states the responsibility for disposal of the low-level radioactive waste generated within their boundaries. It also provides for regional compacts among states to address their needs on a broader basis and permits restriction of the use of regional disposal facilities after January 1, 1986, to generators of low-level waste within the region. Each state, either individually or as a member of a compact, must therefore consider the establishment of a low-level radioactive waste disposal facility within its borders. The states of Arkansas, Kansas, Louisiana, Nebraska, and Oklahoma adopted the Central Interstate Low-Level Waste Compact (CILLWC) and legislation was submitted to Congress for consent in June of 1983 legislation is being reintroduced in the 99th Congress. In August of 1984, the CILLWC selected and contracted Dames and Moore to conduct a Phase I-Site Suitability Screening Study for a low-level radioactive waste disposal facility in the five-state region. This report presents the results of the Phase I Screening Study. Dames and Moore reported to the Technical Advisory Committee (TAC) of the CILLWC which provided guidance and comment on work progress and direction

  17. Fundamental fields around compact objects: Massive spin-2 fields, Superradiant instabilities and Stars with dark matter cores

    CERN Document Server

    Brito, Richard

    2016-01-01

    Fundamental bosonic fields of arbitrary spin are predicted by generic extensions of the Standard Model and of General Relativity, and are well-motivated candidates to explain the dark components of the Universe. One of most promising channels to look for their presence is through their gravitational interaction with compact objects. Within this context, in this thesis I study several mechanisms by which bosonic fields may affect the dynamics and structure of black holes and neutron stars. The first part of the thesis is devoted to the study of massive spin-2 fields around spherically symmetric black-hole spacetimes. Massive spin-2 fields can be consistently described within theories of massive gravity, making it possible to perform a systematic study of the propagation of these fields in curved spacetimes. In particular, I show that due to the presence of additional degrees of freedom in these theories, the structure of black-hole solutions is richer than in General Relativity. In the second part of the thesi...

  18. Multi-epoch VLBA observations of radio galaxy 0932+075: is this a compact symmetric object?

    CERN Document Server

    Marecki, A

    2014-01-01

    A part of the radio structure of the galaxy 0932+075 emerged as a possible compact symmetric object (CSO) after the observation with the Very Long Baseline Array (VLBA) at 5 GHz in 1997. More than a decade later, we carried out observations at 5, 15.4, and 22.2 GHz using the VLBA to test this possibility. We report here that we have found a component whose spectrum is inverted in the whole range from 5 GHz to 22 GHz and we label it a high-frequency peaker (HFP). Using a set of 5 GHz images from two epochs separated by 11.8 years and a set of 15.4 GHz images separated by 8.2 years, we were able to examine the proper motions of the three components of the CSO candidate with respect to the HFP. We found that their displacements cannot be reconciled with the CSO paradigm. This has led to the rejection of the hypothesis that the western part of the arcsecond-scale radio structure of 0932+075 is a CSO anchored at the HFP. Consequently, the HFP cannot be labelled a core and its role in this system is unclear.

  19. 3D Spectroscopy of Local Luminous Compact Blue Galaxies: Kinematic Maps of a Sample of 22 Objects

    CERN Document Server

    Pérez-Gallego, J; Castillo-Morales, A; Gallego, J; Castander, F J; Garland, C A; Gruel, N; Pisano, D J; Zamorano, J

    2011-01-01

    We use three dimensional optical spectroscopy observations of a sample of 22 local Luminous Compact Blue Galaxies (LCBGs) to create kinematic maps. By means of these, we classify the kinematics of these galaxies into three different classes: rotating disk (RD), perturbed rotation (PR), and complex kinematics (CK). We find 48% are RDs, 28% are PRs, and 24% are CKs. RDs show rotational velocities that range between $\\sim50$ and $\\sim200 km s^{-1}$, and dynamical masses that range between $\\sim1\\times10^{9}$ and $\\sim3\\times10^{10} M_{\\odot}$. We also address the following two fundamental questions through the study of the kinematic maps: \\emph{(i) What processes are triggering the current starbust in LCBGs?} We search our maps of the galaxy velocity fields for signatures of recent interactions and close companions that may be responsible for the enhanced star formation in our sample. We find 5% of objects show evidence of a recent major merger, 10% of a minor merger, and 45% of a companion. This argues in favor...

  20. Motion of halo compact objects in the gravitational potential of a low-mass model of the Galaxy

    CERN Document Server

    Sikora, Szymon; Jałocha, Joanna; Kutschera, Marek

    2014-01-01

    Recently, we derived a lower bound for the Galaxy mass in the approximation of a point mass potential, assuming a spherical symmetric ensemble of test bodies representing compact objects of the halo. This result was obtained for a representative of most general phase-space distribution functions consistent with the measured radial velocity dispersion, assuming no constraints on the form of the velocity dispersion anisotropy parameter. In this paper we make use of the representative phase function to set the initial conditions for a simulation of test bodies in a more realistic gravitational potential with the same total mass. The predicted radial velocity dispersion profile evolves to forms still consistent with the measured profile, proving structural stability of the point mass approximation and the reliability of its lower bound estimate for Galaxy mass of about $2.1\\times10^{11}\\mathrm{M}_{\\odot}$ within $150\\,\\mathrm{kpc}$. We derive also a relationship holding in spherical symmetry between the radial ve...

  1. A compact light-sheet microscope for the study of the mammalian central nervous system

    Science.gov (United States)

    Yang, Zhengyi; Haslehurst, Peter; Scott, Suzanne; Emptage, Nigel; Dholakia, Kishan

    2016-05-01

    Investigation of the transient processes integral to neuronal function demands rapid and high-resolution imaging techniques over a large field of view, which cannot be achieved with conventional scanning microscopes. Here we describe a compact light sheet fluorescence microscope, featuring a 45° inverted geometry and an integrated photolysis laser, that is optimized for applications in neuroscience, in particular fast imaging of sub-neuronal structures in mammalian brain slices. We demonstrate the utility of this design for three-dimensional morphological reconstruction, activation of a single synapse with localized photolysis, and fast imaging of neuronal Ca2+ signalling across a large field of view. The developed system opens up a host of novel applications for the neuroscience community.

  2. Radio-optical scrutiny of the central engine in compact AGN

    OpenAIRE

    T. G. Arshakian; V. H. Chavushyan; Ros, E.; Kadler, M.; Zensus, J. A.

    2004-01-01

    We combine Very-Long-Baseline Interferometry (VLBI) data for $\\sim100$ active galactic nuclei (AGN) available from the Very Large Baseline Array (VLBA) 2 cm imaging survey and optical spectroscopy to investigate the relationships in the emission-line region--central engine--radio jet system. Here, we present the diversity of spectral types among the brightest AGN in our sample. We also discuss correlations between the mass of the central engine and properties of the parsec-scale radio jet for...

  3. Objective validation of central sensitization in the rat UVB and heat rekindling model

    OpenAIRE

    Weerasinghe, NS; Lumb, BM; Apps, R; Koutsikou, S; Murrell, JC

    2014-01-01

    Background The UVB and heat rekindling (UVB/HR) model shows potential as a translatable inflammatory pain model. However, the occurrence of central sensitization in this model, a fundamental mechanism underlying chronic pain, has been debated. Face, construct and predictive validity are key requisites of animal models; electromyogram (EMG) recordings were utilized to objectively demonstrate validity of the rat UVB/HR model. Methods The UVB/HR model was induced on the heel of the hind paw unde...

  4. Micro-tidal Disruption Events by Stellar Compact Objects and the Production of Ultra-long GRBs

    Science.gov (United States)

    Perets, Hagai B.; Li, Zhuo; Lombardi, James C., Jr.; Milcarek, Stephen R., Jr.

    2016-06-01

    We explore full/partial tidal disruption events (TDEs) of stars/planets by stellar compact objects (black holes (BHs) or neutron stars (NSs)), which we term micro-TDEs. Disruption of a star/planet with mass M ⋆ may lead to the formation of a debris disk around the BH/NS. Efficient accretion of a fraction ({f}{acc}=0.1 of the debris may then give rise to bright, energetic, long (103–104 s), X-ray/gamma-ray flares, with total energies of up to ({f}{acc}/0.1)× {10}52 ({M}\\star /0.6 {M}ȯ ) erg, possibly resembling ultra-long gamma-ray bursts (GRBs)/X-ray flashes (XRFs). The energy of such flares depends on the poorly constrained accretion processes. Significantly fainter flares might be produced if most of the disk mass is blown away through strong outflows. We suggest three dynamical origins for such disruptions. In the first, a star/planet is tidally disrupted following a close random encounter with a BH/NS in a dense cluster. We estimate the BH (NS) micro-TDE rates from this scenario to be a few × {10}-6 (a few × {10}-7) {{{yr}}}-1 per Milky Way galaxy. Another scenario involves the interaction of wide companions due to perturbations by stars in the field, likely producing comparable but lower rates. Finally, a third scenario involves a BH/NS that gains a natal velocity kick at birth, leading to a close encounter with a binary companion and the tidal disruption of that companion. Such events could be associated with a supernova, or even with a preceding GRB/XRF event, and would likely occur hours to days after the prompt explosion; the rates of such events could be larger than those obtained from the other scenarios, depending on the preceding complex binary stellar evolution.

  5. Neural Responses to Central and Peripheral Objects in the Lateral Occipital Cortex

    Science.gov (United States)

    Wang, Bin; Guo, Jiayue; Yan, Tianyi; Ohno, Seiichiro; Kanazawa, Susumu; Huang, Qiang; Wu, Jinglong

    2016-01-01

    Human object recognition and classification depend on the retinal location where the object is presented and decrease as eccentricity increases. The lateral occipital complex (LOC) is thought to be preferentially involved in the processing of objects, and its neural responses exhibit category biases to objects presented in the central visual field. However, the nature of LOC neural responses to central and peripheral objects remains largely unclear. In the present study, we used functional magnetic resonance imaging (fMRI) and a wide-view presentation system to investigate neural responses to four categories of objects (faces, houses, animals, and cars) in the primary visual cortex (V1) and the lateral visual cortex, including the LOC and the retinotopic areas LO-1 and LO-2. In these regions, the neural responses to objects decreased as the distance between the location of presentation and center fixation increased, which is consistent with the diminished perceptual ability that was found for peripherally presented images. The LOC and LO-2 exhibited significantly positive neural responses to all eccentricities (0–55°), but LO-1 exhibited significantly positive responses only to central eccentricities (0–22°). By measuring the ratio relative to V1 (RRV1), we further demonstrated that eccentricity, category and the interaction between them significantly affected neural processing in these regions. LOC, LO-1, and LO-2 exhibited larger RRV1s when stimuli were presented at an eccentricity of 0° compared to when they were presented at the greater eccentricities. In LOC and LO-2, the RRV1s for images of faces, animals and cars showed an increasing trend when the images were presented at eccentricities of 11 to 33°. However, the RRV1s for houses showed a decreasing trend in LO-1 and no difference in the LOC and LO-2. We hypothesize, that when houses and the images in the other categories were presented in the peripheral visual field, they were processed via

  6. On the Nature of the Compact Object in SS 433. Observational Evidence of X-Ray Photon Index Saturation

    Science.gov (United States)

    Seifina, Elena; Titarchuk, Lev

    2010-01-01

    We present an analysis of the X-ray spectral properties observed from black hole , candidate (BHC) binary SS 433. We have analyzed Rossi X-ray Time Explorer (RXTE) data from this source, coordinated with Green Bank Interferometer/RATAN-600. We show that SS 433 undergoes a X-ray spectral transition from the low hard state (LHS) to the intermediate state (IS). We show that the X-ray broad-band energy spectra during all spectral states are well fit by a sum of so called "Bulk Motion Comptonization (BMC) component" and by two (broad and narrow) Gaussians for the continuum and line emissions respectively. In addition to these spectral model components we also find a strong feature that we identify as a" blackbody-like (BB)" component which color temperature is in the range of 4-5 keV in 24 IS spectra during the radio outburst decay in SS 433. Our observational results on the "high temperature BB" bump leads us to suggest the presence of gravitationally redshifted annihilation line emission in this source. In fact this spectral feature has been recently reproduced in Monte Carlo simulations by Laurent and Titarchuk. We have also established the photon index saturation at about 2.3 in index vs mass accretion correlation. This index-mass accretion correlation allows us to evaluate the low limit of black hole (BH) mass of compact object in SS 433, M(sub bh) approximately > 2 solar masses, using the scaling method using BHC GX 339-4 as a reference source. Our estimate of the BH mass in SS 433 is consistent with recent BH mass measurement using the radial-velocity measurements of the binary system by Hillwig & Gies who find that M(sub x)( = (4.3 +/- 0.8) solar masses. This is the smallest BH mass found up to now among all BH sources. Moreover, the index saturation effect versus mass accretion rate revealed in SS 433, like in a number of other BH candidates, is the strong observational evidence for the presence of a BH in SS 433.

  7. Association between birth weight and objectively measured sedentary time is mediated by central adiposity

    DEFF Research Database (Denmark)

    Hildebrand, Maria; Kolle, Elin; Hansen, Bjørge H;

    2015-01-01

    BACKGROUND: Birth weight is an early correlate of disease later in life, and animal studies suggest that low birth weight is associated with reduced activity and increased sedentary time. Whether birth weight predicts later sedentary time in humans is uncertain. OBJECTIVES: We examined the relation.......001). Results of the mediation analysis showed a significant indirect effect of birth weight on sedentary time through waist circumference (B: 1.30; 95% bias-corrected CI: 0.94, 1.72), and when waist circumference was controlled for, the effect of birth weight on sedentary time was attenuated by 32% (B = 2...... between birth weight and sedentary time in youth and examined whether this association was mediated by central adiposity. DESIGN: We used pooled cross-sectional data from 8 observational studies conducted between 1997 and 2007 that consisted of 10,793 youth (boys: 47%) aged 6-18 y from the International...

  8. [Improving the Care Accuracy of Percutaneously Inserted Central Catheters Using Objective Structured Clinical Examination].

    Science.gov (United States)

    Yang, Pei-Hsin; Hsu, Hsin-Chieh; Chiang, Chia-Chin; Tseng, Yun-Shan

    2016-06-01

    Approximately 9,800 adverse events related to medical tubing are reported in Taiwan every year. Most neonates in critical condition and premature infants acquire fluid, nutrition, and infusion solution using percutaneously inserted central catheters (PICCs). Objective structured clinical examination (OSCE) is an objective evaluative tool that may be used to measure the clinical competence of healthcare professionals. Very little is known about the effects of OSCE in Taiwan in terms of improving the accuracy of use of PICCs in nursing care and of reducing unexpected medical tubing removals. The present project aimed to explore the effects of an OSCE course on these two issues in the realms of standard operating procedures, care protocols, and training equipment at a neonatal intermediate unit in Taiwan. The duration of the present study ran from 2/20/2013 to 10/30/2013. The results showed that nurses' knowledge of PICCs improved from 87% to 91.5%; nurses' skill-care accuracy related to PICCs improved from 59.1% to 97.3%; and incidents of unexpected tube removals declined from 63.6% to 16.7%. This project demonstrated that OSCE courses improve the quality of PICC nursing care. Additionally, the instant feedback mechanism within the OSCE course benefited both teachers and students. PMID:27250965

  9. OBSERVATIONAL UPPER BOUND ON THE COSMIC ABUNDANCES OF NEGATIVE-MASS COMPACT OBJECTS AND ELLIS WORMHOLES FROM THE SLOAN DIGITAL SKY SURVEY QUASAR LENS SEARCH

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Ryuichi; Asada, Hideki [Faculty of Science and Technology, Hirosaki University, Hirosaki 036-8561 (Japan)

    2013-05-01

    The latest result in the Sloan Digital Sky Survey Quasar Lens Search (SQLS) has set the first cosmological constraints on negative-mass compact objects and Ellis wormholes. There are no multiple images lensed by the above two exotic objects for {approx}50, 000 distant quasars in the SQLS data. Therefore, an upper bound is put on the cosmic abundances of these lenses. The number density of negative-mass compact objects is n < 10{sup -8}(10{sup -4}) h {sup 3} Mpc{sup -3} at the mass scale |M| > 10{sup 15}(10{sup 12}) M{sub Sun }, which corresponds to the cosmological density parameter |{Omega}| < 10{sup -4} at the galaxy and cluster mass range |M| = 10{sup 12-15} M{sub Sun }. The number density of the Ellis wormhole is n < 10{sup -4} h {sup 3} Mpc{sup -3} for a range of the throat radius a = 10-10{sup 4} pc, which is much smaller than the Einstein ring radius.

  10. NuSTAR and XMM-Newton observations of 1E1743.1-2843: indications of a neutron star LMXB nature of the compact object

    CERN Document Server

    Lotti, Simone; Mori, Kaya; Baganoff, Frederick K; Boggs, Steven E; Christensen, Finn E; Craig, William W; Hailey, Charles J; Harrison, Fiona A; Hong, Jaesub; Krivonos, Roman A; Rahoui, Farid; Stern, Daniel; Tomsick, John A; Zhang, Shuo; Zhang, William W

    2016-01-01

    We report on the results of NuSTAR and XMM-Newton observations of the persistent X-ray source \\object{1E1743.1-2843}, located in the Galactic Center region. The source was observed between September and October 2012 by NuSTAR and XMM-Newton, providing almost simultaneous observations in the hard and soft X-ray bands. The high X-ray luminosity points to the presence of an accreting compact object. We analyze the possibilities of this accreting compact object being either a neutron star (NS) or a black hole, and conclude that the joint XMM-Newton and NuSTAR spectrum from 0.3 to 40 $\\mathrm{keV}$ fits to a black body spectrum with $kT\\sim1.8~\\mathrm{keV}$ emitted from a hot spot or an equatorial strip on a neutron star surface. This spectrum is thermally Comptonized by electrons with $kT_{e}\\sim4.6~\\mathrm{keV}$. Accepting this neutron star hypothesis, we probe the Low Mass (LMXB) or High Mass (HMXB) X-ray Binary nature of the source. While the lack of Type-I bursts can be explained in the LMXB scenario, the abs...

  11. Dark matter mini-halo around the compact objects: the formation, evolution and possible contribution to the cosmic ray electrons/positrons

    International Nuclear Information System (INIS)

    Dark matter particles may be captured by a star and then thermalized in the star's core. At the end of its life a massive star collapses suddenly and a compact object is formed. The dark matter particles redistribute accordingly. In the inelastic dark matter model, an extended dense dark matter mini-halo surrounding the neutron star may be formed. Such mini-halos may be common in the Galaxy. The electron/positron flux resulting in the annihilation of dark matter particles, however, is unable to give rise to observable signal unless a nascent mini-halo is within a distance ∼ a few 0.1 pc from the Earth

  12. Next-to-leading order spin-orbit and spin(a)-spin(b) Hamiltonians for n gravitating spinning compact objects

    CERN Document Server

    Hartung, Johannes

    2010-01-01

    We derive the post-Newtonian next-to-leading order conservative spin-orbit and spin(a)-spin(b) gravitational interaction Hamiltonians for arbitrary many compact objects. The spin-orbit Hamiltonian completes the knowledge of Hamiltonians up to and including 2.5PN for the general relativistic three-body problem. The new Hamiltonians include highly nontrivial three-body interactions, in contrast to the leading order consisting of two-body interactions only. This may be important for the study of effects like Kozai resonances in mergers of black holes with binary black holes.

  13. Thermodynamics of static black objects in D dimensional Einstein-Gauss-Bonnet gravity with D-4 compact dimensions

    OpenAIRE

    Sahabandu, C.; Suranyi, P.; Vaz, C; Wijewardhana, L. C. R.

    2005-01-01

    We investigate the thermodynamics of static black objects such as black holes, black strings and their generalizations to D dimensions (`black branes') in a gravitational theory containing the four dimensional Gauss-Bonnet term in the action, when D-4 of the dimensions are compactified on a torus. The entropies of black holes and black branes are compared to obtain information on the stability of these objects and to find their phase diagrams. We demonstrate the existence of a critical mass, ...

  14. Thermodynamics of static black objects in D dimensional Einstein-Gauss-Bonnet gravity with D-4 compact dimensions

    Science.gov (United States)

    Sahabandu, C.; Suranyi, P.; Vaz, C.; Wijewardhana, L. C.

    2006-02-01

    We investigate the thermodynamics of static black objects such as black holes, black strings and their generalizations to D dimensions (“black branes”) in a gravitational theory containing the four-dimensional Gauss-Bonnet term in the action, with D-4 dimensions compactified torus. The entropies of black holes and black branes are compared to obtain information on the stability of these objects and to find their phase diagrams. We demonstrate the existence of a critical mass, which depends on the scale of the compactified dimensions, below which the black hole entropy dominates over the entropy of the black membrane.

  15. Thermodynamics of static black objects in $D$ dimensional Einstein-Gauss-Bonnet gravity with $D-4$ compact dimensions

    CERN Document Server

    Sahabandu, C; Vaz, C; Wijewardhana, L C R

    2006-01-01

    We investigate the thermodynamics of static black objects such as black holes, black strings and their generalizations to D dimensions (`black branes') in a gravitational theory containing the four dimensional Gauss-Bonnet term in the action, when D-4 of the dimensions are compactified on a torus. The entropies of black holes and black branes are compared to obtain information on the stability of these objects and to find their phase diagrams. We demonstrate the existence of a critical mass, which depends on the scale of the compactified dimensions, below which the black hole entropy dominates over the entropy of the black membrane.

  16. Measurement of the abundance of stellar mass compact objects in the galactic halo by detecting micro-lenses in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Many experimental and theoretical results lead to the conclusion that at least 80 percent of the mass of our Galaxy is dark. Part of this so-called dark matter could be in the form of stellar mass compact objects, called MACHOS; these could be detected using the gravitational microlensing effect. The first generation experiments EROS1 and MACHO have strongly constrained the galactic abundance of objects lighter than 0.01 solar mass to less than 10 percent of the total mass. In parallel, the observation by the MACHO group of massive candidates (half the Sun's mass), numerous enough to constitute 50 percent of galactic dark matter, was a further motivation for the EROS group to extend this search to stellar mass objects in a second phase, EROS2. The present work deals with the analysis of 25 million stellar light curves in the Large Magellanic Cloud, observed for three years in order to extract the rare microlensing candidates and to measure the galactic halo mass fraction in the form of compact objects. After recalling the motivations of this search and the theoretical context, I describe the EROS2 experiment. The observational strategy and the photometric reduction procedures needed to deal with the 1.2 To of data are then presented. A new method to detect micro-lenses is detailed, as well as a discussion of background light curves, poorly known. We do not find enough microlensing candidates to explain the galactic rotation curve; this confirms, and improve on previous EROS1 and EROS2 results. Combining all results from EROS allows to exclude that MACHOS with a mass between 10 e-7 and 10 solar mass are important constituents of the galactic halo. This statement agrees with recent results from the MACHO group, although our interpretations differ, namely on the topics of the location of the lenses, and of a possible contamination of the microlensing ample by background phenomena. (author)

  17. Information-Entropic Stability Bound for Compact Objects: Application to Q-Balls and the Chandrasekhar Limit of Polytropes

    CERN Document Server

    Gleiser, Marcelo

    2013-01-01

    Spatially-bound objects across diverse length and energy scales are characterized by a binding energy. We propose that their spatial structure is mathematically encoded as information in their momentum modes and described by a measure known as configurational entropy (CE). Investigating solitonic Q-balls and stars with a polytropic equation of state $P = K{\\rho}^{\\gamma}$, we show that objects with large binding energy have low CE, whereas those at the brink of instability (zero binding energy) have near maximal CE. In particular, we use the CE to find the critical charge allowing for classically stable Q-balls and the Chandrasekhar limit for white dwarfs $({\\gamma} = 4/3)$ with an accuracy of a few percent.

  18. Information-entropic stability bound for compact objects: Application to Q-balls and the Chandrasekhar limit of polytropes

    Energy Technology Data Exchange (ETDEWEB)

    Gleiser, Marcelo, E-mail: mgleiser@dartmouth.edu; Sowinski, Damian, E-mail: Damian.Sowinski.GR@dartmouth.edu

    2013-11-25

    Spatially-bound objects across diverse length and energy scales are characterized by a binding energy. We propose that their spatial structure is mathematically encoded as information in their momentum modes and described by a measure known as configurational entropy (CE) [1]. Investigating solitonic Q-balls and stars with a polytropic equation of state P=Kρ{sup γ}, we show that objects with large binding energy have low CE, whereas those at the brink of instability (zero binding energy) have near maximal CE. In particular, we use the CE to find the critical charge allowing for classically stable Q-balls and the Chandrasekhar limit for white dwarfs (γ=4/3) with an accuracy of a few percent.

  19. First Detection in Gamma-Rays of a Young Radio Galaxy: Fermi-LAT Observations of the Compact Symmetric Object PKS 1718-649

    Science.gov (United States)

    Migliori, G.; Siemiginowska, A.; Sobolewska, M.; Loh, A.; Corbel, S.; Ostorero, L.; Stawarz, Ł.

    2016-04-01

    We report the γ-ray detection of a young radio galaxy, PKS 1718-649, belonging to the class of compact symmetric objects (CSOs), with the Large Area Telescope (LAT) on board the Fermi satellite. The third Fermi Gamma-ray LAT catalog (3FGL) includes an unassociated γ-ray source, 3FGL J1728.0-6446, located close to PKS 1718-649. Using the latest Pass 8 calibration, we confirm that the best-fit 1σ position of the γ-ray source is compatible with the radio location of PKS 1718-649. Cross-matching of the γ-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718-649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS ˜ 36 (>5σ) with a best-fit photon spectral index Γ = 2.9 ± 0.3 and a 0.1-100 GeV photon flux density F 0.1-100 GeV = (11.5 ± 0.3) × 10-9 ph cm-2 s-1. We argue that the linear size (˜2 pc), the kinematic age (˜100 years), and the source distance (z = 0.014) make PKS 1718-649 an ideal candidate for γ-ray detection in the framework of the model proposing that the most compact and the youngest CSOs can efficiently produce GeV radiation via inverse-Compton scattering of the ambient photon fields by the radio lobe non-thermal electrons. Thus, our detection of the source in γ-rays establishes young radio galaxies as a distinct class of extragalactic high-energy emitters and yields a unique insight on the physical conditions in compact radio lobes interacting with the interstellar medium of the host galaxy.

  20. Next-to-leading order spin-orbit and spin(a)-spin(b) Hamiltonians for arbitrary many gravitating spinning compact objects

    Energy Technology Data Exchange (ETDEWEB)

    Hartung, Johannes; Steinhoff, Jan [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2011-07-01

    At the next-to-leading order spin-orbit and spin(a)-spin(b) interaction levels, counted within a post-Newtonian approximation scheme, the complexity of Einstein's general relativity becomes apparent. Due to the nonlinearity of the field equations there appear certain three-body interaction terms in the respective Hamiltonians. In this talk we discuss those gravitational three-body correlations. Afterwards an outline of the derivation of the Hamiltonians mentioned above for arbitrary many compact objects is given. A discussion of the relative strength of the next-to-leading order interaction terms in relation to the leading order ones - via a preliminary analysis of certain special configurations of the three-body system - is provided.

  1. Approaching the Post-Newtonian Regime with Numerical Relativity: A Compact-Object Binary Simulation Spanning 350 Gravitational-Wave Cycles.

    Science.gov (United States)

    Szilágyi, Béla; Blackman, Jonathan; Buonanno, Alessandra; Taracchini, Andrea; Pfeiffer, Harald P; Scheel, Mark A; Chu, Tony; Kidder, Lawrence E; Pan, Yi

    2015-07-17

    We present the first numerical-relativity simulation of a compact-object binary whose gravitational waveform is long enough to cover the entire frequency band of advanced gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, for mass ratio 7 and total mass as low as 45.5M_{⊙}. We find that effective-one-body models, either uncalibrated or calibrated against substantially shorter numerical-relativity waveforms at smaller mass ratios, reproduce our new waveform remarkably well, with a negligible loss in detection rate due to modeling error. In contrast, post-Newtonian inspiral waveforms and existing calibrated phenomenological inspiral-merger-ringdown waveforms display greater disagreement with our new simulation. The disagreement varies substantially depending on the specific post-Newtonian approximant used. PMID:26230780

  2. The Chinese space millimeter-wavelength VLBI array - a step toward imaging the most compact astronomical objects

    CERN Document Server

    Hong, Xiaoyu; An, Tao; Liu, Qinghui

    2014-01-01

    The Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences (CAS) is studying a space VLBI (Very Long Baseline Interferometer) program. The ultimate objective of the program is to image the immediate vicinity of the supermassive black holes (SMBHs) in the hearts of galaxies with a space-based VLBI array working at sub-millimeter wavelengths and to gain ultrahigh angular resolution. To achieve this ambitious goal, the mission plan is divided into three stages. The first phase of the program is called Space Millimeter-wavelength VLBI Array (SMVA) consisting of two satellites, each carrying a 10-m diameter radio telescope into elliptical orbits with an apogee height of 60000 km and a perigee height of 1200 km. The VLBI telescopes in space will work at three frequency bands, 43, 22 and 8 GHz. The 43- and 22-GHz bands will be equipped with cryogenic receivers. The space telescopes, observing together with ground-based radio telescopes, enable the highest angular resolution of 20 micro-arcsecond...

  3. Exploring a New Population of Compact Objects: X-ray and IR Observations of the Galactic Centre

    CERN Document Server

    Bandyopadhyay, Reba M; Eikenberry, Stephen E; Muno, Michael P; Blundell, Katherine M; Podsiadlowski, Philipp; Mikles, Valerie J; DeWitt, Curtis

    2008-01-01

    I describe the IR and X-ray observational campaign we have undertaken for the purpose of determining the nature of the faint discrete X-ray source population discovered by Chandra in the Galactic Center (GC). Data obtained for this project includes a deep Chandra survey of the Galactic Bulge; deep, high resolution IR imaging from VLT/ISAAC, CTIO/ISPI, and the UKIDSS Galactic Plane Survey (GPS); and IR spectroscopy from VLT/ISAAC and IRTF/SpeX. By cross-correlating the GC X-ray imaging from Chandra with our IR surveys, we identify candidate counterparts to the X-ray sources via astrometry. Using a detailed IR extinction map, we are deriving magnitudes and colors for all the candidates. Having thus established a target list, we will use the multi-object IR spectrograph FLAMINGOS-2 on Gemini-South to carry out a spectroscopic survey of the candidate counterparts, to search for emission line signatures which are a hallmark of accreting binaries. By determining the nature of these X-ray sources, this FLAMINGOS-2 G...

  4. NuSTAR and XMM-Newton Observations of 1E1743.1-2843: Indications of a Neutron Star LMXB Nature of the Compact Object

    Science.gov (United States)

    Lotti, Simone; Natalucci, Lorenzo; Mori, Kaya; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Hong, Jaesub; Krivonos, Roman A.; Rahoui, Farid; Stern, Daniel; Tomsick, John A.; Zhang, Shuo; Zhang, William W.

    2016-05-01

    We report on the results of NuSTAR and XMM-Newton observations of the persistent X-ray source 1E1743.1-2843, located in the Galactic Center region. The source was observed between 2012 September and October by NuSTAR and XMM-Newton, providing almost simultaneous observations in the hard and soft X-ray bands. The high X-ray luminosity points to the presence of an accreting compact object. We analyze the possibilities of this accreting compact object being either a neutron star (NS) or a black hole, and conclude that the joint XMM-Newton and NuSTAR spectrum from 0.3 to 40 keV fits a blackbody spectrum with {kT}˜ 1.8 {keV} emitted from a hot spot or an equatorial strip on an NS surface. This spectrum is thermally Comptonized by electrons with {{kT}}e˜ 4.6 {keV}. Accepting this NS hypothesis, we probe the low-mass X-ray binary (LMXB) or high-mass X-ray binary (HMXB) nature of the source. While the lack of Type-I bursts can be explained in the LMXB scenario, the absence of pulsations in the 2 mHz-49 Hz frequency range, the lack of eclipses and of an IR companion, and the lack of a {K}α line from neutral or moderately ionized iron strongly disfavor interpreting this source as a HMXB. We therefore conclude that 1E1743.1-2843 is most likely an NS-LMXB located beyond the Galactic Center. There is weak statistical evidence for a soft X-ray excess which may indicate thermal emission from an accretion disk. However, the disk normalization remains unconstrained due to the high hydrogen column density ({N}{{H}}˜ 1.6× {10}23 {{cm}}-2).

  5. Consent of the Congress to the Central Midwest Interstate Low-level Radioactive Waste Compact. Report submitted to the US House of Representatives, Ninety-Ninth Congress, First Session, October 22, 1985

    International Nuclear Information System (INIS)

    The Committee recommendations and suggested amendments for H.R. 2062 describe the Central Midwest Interstate Low-Level Radioactive Waste Compact, which has been ratified by Illinois and Kentucky. Other states will be eligible to participate by following the compact procedures. The report summarizes the legislation, which permits a regional compact to handle, allocate, and regulate low-level wastes. It also establishes the conditions for the congressional consent, gives a section-by-section analysis of the provisions and obligations of member states, and concludes that the higher cost of waste disposal due to new facilities will not be inflationary

  6. Accelerating Compact Object Mergers in Triple Systems with the Kozai Resonance: A Mechanism for "Prompt" Type Ia Supernovae, Gamma-Ray Bursts, and Other Exotica

    Science.gov (United States)

    Thompson, Todd A.

    2011-11-01

    White dwarf-white dwarf (WD-WD) and neutron star-neutron star (NS-NS) mergers may produce Type Ia supernovae and gamma-ray bursts (GRBs), respectively. A general problem is how to produce binaries with semi-major axes small enough to merge in significantly less than the Hubble time (t H), and thus accommodate the observation that these events closely follow episodes of star formation. I explore the possibility that such systems are not binaries at all, but actually coeval, or dynamical formed, triple systems. The tertiary induces Kozai oscillations in the inner binary, driving it to high eccentricity, and reducing its gravitational wave (GW) merger timescale. This effect significantly increases the allowed range of binary period P such that the merger time is t merge tertiary at high enough inclination. For retrograde tertiaries, the maximum P such that t merge tertiary. I discuss implications of these findings for the production of transients formed via compact object binary mergers. Based on the statistics of solar-type binaries, I argue that many such binaries should be in triple systems affected by the Kozai resonance. If true, expectations for the mHz GW signal from individual sources, the diffuse background, and the foreground for GW experiments like LISA are modified. This work motivates future studies of triples systems of A, B, and O stars, and new types of searches for WD-WD binaries in triple systems.

  7. First detection in gamma-rays of a young radio galaxy: Fermi-LAT observations of the Compact Symmetric Object PKS 1718-649

    CERN Document Server

    Migliori, Giulia; Sobolewska, Malgorzata; Loh, Alan; Corbel, Stéphane; Ostorero, Luisa; Stawarz, Łukasz

    2016-01-01

    We report the $\\gamma$-ray detection of a young radio galaxy, PKS 1718$-$649, belonging to the class of Compact Symmetric Objects (CSOs), with the Large Area Telescope (LAT) on board the {\\it Fermi} satellite. The third {\\it Fermi} Gamma-ray LAT catalog (3FGL) includes an unassociated $\\gamma$-ray source, 3FGL J1728.0$-$6446, located close to PKS 1718$-$649. Using the latest Pass 8 calibration, we confirm that the best fit $1 \\sigma$ position of the $\\gamma$-ray source is compatible with the radio location of PKS 1718$-$649. Cross-matching of the $\\gamma$-ray source position with the positions of blazar sources from several catalogs yields negative results. Thus, we conclude that PKS 1718$-$649 is the most likely counterpart to the unassociated LAT source. We obtain a detection test statistics TS$\\sim 36$ ($>$5$\\sigma$) with a best fit photon spectral index $\\Gamma=$2.9$\\pm$0.3 and a 0.1-100 GeV photon flux density $F_{\\rm 0.1-100GeV}=$(11.5$\\pm$0.3)$\\times{\\rm 10^{-9}}$ ph cm$^{-2}$ s$^{-1}$. We argue that t...

  8. Radiation-hazardous objects at the west and central Kazakstan territory

    International Nuclear Information System (INIS)

    In 1965-1987, there were conducted 39 industrial underground explosions in the territory of Kazakhstan Republic, in particular in its west and central region (explosions conducted at Semipalatinsk test site, East-Kazakhstan oblates are not included). These explosions were conducted in terms of the Program 7 Peaceful nuclear explosions for industrial purposes with the purpose of test-industrial investigation conducting for testing a technology for formation of cavities in rock salt in order to be used as multipurpose large volume storage. Energy from underground nuclear explosions was used for peaceful technological purposes, in particular, in the territories of hydrocarbon raw materials mining and industrial developing. It is obvious, that residual radioactivity, even if it is very small, is a factor, that hampers to use nuclear explosions for this purpose. The major problems are the following: safety measures, which are necessary for implementation of the projects on nuclear explosion usage in peaceful purposes, admissible level of environment pollution in whole and possible consequences. All necessary measures must be taken to ensure safety in the regions, where explosions were conducted, including all the least probable accidents (for instance, breach during camuflet explosions). To make sure, that existing admissible standards will not be exceeded, it is necessary to know the level of environment radiation contamination and to forecast probable contamination caused by explosions

  9. Object based change detection of Central Asian Tugai vegetation with very high spatial resolution satellite imagery

    Science.gov (United States)

    Gärtner, Philipp; Förster, Michael; Kurban, Alishir; Kleinschmit, Birgit

    2014-09-01

    Ecological restoration of degraded riparian Tugai forests in north-western China is a key driver to combat desertification in this region. Recent restoration efforts attempt to recover the forest along with its most dominant tree species, Populus euphratica. The present research observed the response of natural vegetation using an object based change detection method on QuickBird (2005) and WorldView2 (2011) data. We applied the region growing approach to derived Normalized Difference Vegetation Index (NDVI) values in order to identify single P. euphratica trees, delineate tree crown areas and quantify crown diameter changes. Results were compared to 59 reference trees. The findings confirmed a positive tree crown growth and suggest a crown diameter increase of 1.14 m, on average. On a single tree basis, tree crown diameters of larger crowns were generally underestimated. Small crowns were slightly underestimated in QuickBird and overestimated in Worldview2 images. The results of the automated tree crown delineation show a moderate relation to field reference data with R20052: 0.36 and R20112: 0.48. The object based image analysis (OBIA) method proved to be applicable in sparse riparian Tugai forests and showed great suitability to evaluate ecological restoration efforts in an endangered ecosystem.

  10. Oscillating shells: A model for a variable cosmic object

    OpenAIRE

    Nunez, Dario

    1997-01-01

    A model for a possible variable cosmic object is presented. The model consists of a massive shell surrounding a compact object. The gravitational and self-gravitational forces tend to collapse the shell, but the internal tangential stresses oppose the collapse. The combined action of the two types of forces is studied and several cases are presented. In particular, we investigate the spherically symmetric case in which the shell oscillates radially around a central compact object.

  11. Oscillating shells A model for a variable cosmic object

    CERN Document Server

    Núñez, D

    1997-01-01

    A model for a possible variable cosmic object is presented. The model consists of a massive shell surrounding a compact object. The gravitational and self-gravitational forces tend to collapse the shell, but the internal tangential stresses oppose the collapse. The combined action of the two types of forces is studied and several cases are presented. In particular, we investigate the spherically symmetric case in which the shell oscillates radially around a central compact object.

  12. Granting the consent of the Congress to the Central Interstate Low-level Radioactive Waste Compact. Report submitted to the US House of Representatives, Ninety-Ninth Congress, First Session, October 22, 1985

    International Nuclear Information System (INIS)

    The committee recommendation and suggested amendments for H.R. 1046 describes the Central Interstate Low-Level Radioactive Waste Compact, which has been ratified by Kansas, Louisiana, Arkansas, Oklahoma, and Nebraska. Iowa, Minnesota, Missouri, and North Dakota are also eligible to participate in the regional compact. The report summarizes the legislation, which permits a regional compact to handle, allocate, and regulate low-level wastes. It also establishes the conditions for the congressional consent, gives a section-by-section analysis of the compact's provisions and requirements for member states, and concludes that the cost of waste facilities will not be inflationary or result in any significant cost to any level of government

  13. STAR FORMATION IN THE CENTRAL 400 PC OF THE MILKY WAY: EVIDENCE FOR A POPULATION OF MASSIVE YOUNG STELLAR OBJECTS

    International Nuclear Information System (INIS)

    The central kpc of the Milky Way might be expected to differ significantly from the rest of the Galaxy with regard to gasdynamics and the formation of young stellar objects (YSOs). We probe this possibility with mid-infrared observations obtained with Infrared Array Camera and Multiband Imaging Photometer on Spitzer and with Midcourse Space Experiment. We use color-color diagrams and spectral energy distribution (SED) fits to explore the nature of YSO candidates (including objects with 4.5 μm excesses possibly due to molecular emission). There is an asymmetry in the distribution of the candidate YSOs, which tend to be found at negative Galactic longitudes; this behavior contrasts with that of the molecular gas, approximately 2/3 of which is at positive longitudes. The small-scale height of these objects suggests that they are within the Galactic center region and are dynamically young. They lie between two layers of infrared dark clouds and may have originated from these clouds. We identify new sites for this recent star formation by comparing the mid-IR, radio, submillimeter, and methanol maser data. The methanol masers appear to be associated with young, embedded YSOs characterized by 4.5 μm excesses. We use the SEDs of these sources to estimate their physical characteristics; their masses appear to range from ∼10 to ∼20 Msun. Within the central 400 x 50 pc (|l| 03 and |b| sun yr-1. Given that the majority of the sources in the population of YSOs are classified as Stage I objects, we suggest that a recent burst of star formation took place within the last 105 yr. This suggestion is also consistent with estimates of SFRs within the last ∼107 yr showing a peak around 105 yr ago. Lastly, we find that the Schmidt-Kennicutt Law applies well in the central 400 pc of the Galaxy. This implies that star formation does not appear to be dramatically affected by the extreme physical conditions in the Galactic center region.

  14. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    International Nuclear Information System (INIS)

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center

  15. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    Prodan, Snezana; Antonini, Fabio [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, University of Toronto, Toronto, ON M5S 3H8 (Canada); Perets, Hagai B., E-mail: sprodan@cita.utoronto.ca, E-mail: antonini@cita.utoronto.ca [Physics Department, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2015-02-01

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center.

  16. COMPACT OPERATORS

    Directory of Open Access Journals (Sweden)

    Charles Swartz

    2009-12-01

    Full Text Available We give a characterization in terms of the transpose operator for a continuous linear operator between locally convex spaces to map bounded sets into relatively weakly compact [relatively compact, precompact] sets. Our results give a known characterization for compact operators between Banach spaces.

  17. Uniaxial backfill block compaction

    International Nuclear Information System (INIS)

    The main parts of the project were: to make a literature survey of the previous uniaxial compaction experiments; do uniaxial compaction tests in laboratory scale; and do industrial scale production tests. Object of the project was to sort out the different factors affecting the quality assurance chain of the backfill block uniaxial production and solve a material sticking to mould problem which appeared during manufacturing the blocks of bentonite and cruched rock mixture. The effect of mineralogical and chemical composition on the long term functionality of the backfill was excluded from the project. However, the used smectite-rich clays have been tested for mineralogical consistency. These tests were done in B and Tech OY according their SOPs. The objective of the Laboratory scale tests was to find right material- and compaction parameters for the industrial scale tests. Direct comparison between the laboratory scale tests and industrial scale tests is not possible because the mould geometry and compaction speed has a big influence for the compaction process. For this reason the selected material parameters were also affected by the previous compaction experiments. The industrial scale tests were done in summer of 2010 in southern Sweden. Blocks were done with uniaxial compaction. A 40 tons of the mixture of bentonite and crushed rock blocks and almost 50 tons of Friedland-clay blocks were compacted. (orig.)

  18. A pedagogical history of compactness

    OpenAIRE

    Raman-Sundström, Manya

    2010-01-01

    Compactness is a central notion in advanced mathematics, but we often teach the concept without much historical motivation.  This paper fills in many of the gaps left by the standard textbook treatment, including what motivated the definition, how did the definition evolve, and how can compactness be expressed in terms of nets and filters.

  19. An Extended Star Formation History in an Ultra Compact Dwarf

    CERN Document Server

    Norris, Mark A; Faifer, Favio R; Kannappan, Sheila J; Forte, Juan Carlos; Bosch, Remco C E van den

    2015-01-01

    There has been significant controversy over the mechanisms responsible for forming compact stellar systems like ultra compact dwarfs (UCDs), with suggestions that UCDs are simply the high mass extension of the globular cluster (GC) population, or alternatively, the liberated nuclei of galaxies tidally stripped by larger companions. Definitive examples of UCDs formed by either route have been difficult to find, with only a handful of persuasive examples of stripped-nucleus type UCDs being known. In this paper we present very deep Gemini/GMOS spectroscopic observations of the suspected stripped nucleus UCD NGC 4546-UCD1 taken in good seeing conditions (< 0.7"). With these data we examine the spatially resolved kinematics and star formation history of this unusual object. We find no evidence of a rise in the central velocity dispersion of the UCD, suggesting that this UCD lacks a massive central black hole like those found in some other compact stellar systems, a conclusion confirmed by detailed dynamical mod...

  20. H.R. 1046: a bill to grant the consent of the Congress to the Central Interstate Low-Level Radioactive Waste Compact. Introduced in the House of Representatives, Ninety-Ninth Congress, First Session, February 7, 1985

    International Nuclear Information System (INIS)

    The House version of the Central Interstate Low-Level Radioactive Waste Compact (H.R. 1046) establishes Congressional consent for Arkansas, Iowa, Kansas, Kouisiana, Minnesota, Missouri, Nebraska, North Dakota, and Oklahoma to cooperate on a regional basis in managing and storing low-level radioactive wastes. The purpose of the compact is to help the participating states establish an equitable distribution of the costs and benefits and to encourage those who generate low-level wastes to reduce the quantity. The bill defines pertinent terms, outlines the rights and responsibilities of participating states in maintaining a storage facility, establishes a managing commission, and specifies how the commission should develop and operate a regional facility

  1. Self-Consistent Thermal Accretion Disk Corona Models for Compact Objects. I: Properties of the Corona and the Spectrum of Escaping Radiation

    Science.gov (United States)

    Dove, James B.; Wilms, Jorn; Begelman, Mitchell C.

    1997-01-01

    We present the properties of accretion disk corona (ADC) models in which the radiation field, the temperature, and the total opacity of the corona are determined self-consistently. We use a nonlinear Monte Carlo code to perform the calculations. As an example, we discuss models in which the corona is situated above and below a cold accretion disk with a plane-parallel (slab) geometry, similar to the model of Haardt & Maraschi. By Comptonizing the soft radiation emitted by the accretion disk, the corona is responsible for producing the high-energy component of the escaping radiation. Our models include the reprocessing of radiation in the accretion disk. Here the photons either are Compton-reflected or photoabsorbed, giving rise to fluorescent line emission and thermal emission. The self- consistent coronal temperature is determined by balancing heating (due to viscous energy dissipation) with Compton cooling, determined using the fully relativistic, angle-dependent cross sections. The total opacity is found by balancing pair productions with annihilations. We find that, for a disk temperature kT(sub BB) approx. less than 200 eV, these coronae are unable to have a self-consistent temperature higher than approx. 140 keV if the total optical depth is approx. less than 0.2, regardless of the compactness parameter of the corona and the seed opacity. This limitation corresponds to the angle-averaged spectrum of escaping radiation having a photon index approx. greater than 1.8 within the 5-30 keV band. Finally, all models that have reprocessing features also predict a large thermal excess at lower energies. These constraints make explaining the X-ray spectra of persistent black hole candidates with ADC models very problematic.

  2. Nonthermal X-Rays from Supernova Remnant G330.2+1.0 and the Characteristics of its Central Compact Object

    CERN Document Server

    Park, Sangwook; Pavlov, George G; Mori, Koji; Slane, Patrick O; Hughes, John P; Burrows, David N; Garmire, Gordon P

    2008-01-01

    We present results from our X-ray data analysis of the SNR G330.2+1.0 and its CCO, CXOU J160103.1--513353 (J1601). Using our XMM-Newton and Chandra observations, we find that the X-ray spectrum of J1601 can be described by neutron star atmosphere models (T ~ 2.5--3.7 MK). Assuming the distance of d ~ 5 kpc for J1601 as estimated for SNR G330.2+1.0, a small emission region of R ~ 1--2 km is implied. X-ray pulsations previously suggested by Chandra are not confirmed by the XMM-Newton data. However, our timing analysis of the XMM-Newton data is limited by poor photon statistics, and thus pulsations with a relatively low amplitude (i.e., an intrinsic pulsed-fraction < 40%) cannot be ruled out. Our results indicate that J1601 is a CCO similar to that in the Cassiopeia A SNR.X-ray emission from SNR G330.2+1.0 is dominated by power law continuum (Gamma ~ 2.1--2.5) which primarily originates from thin filaments along the boundary shell. This X-ray spectrum implies synchrotron radiation from shock-accelerated elect...

  3. Granting the consent of the Congress to the Central Midwest Interstate Low-Level Radioactive Waste Compact. A report submitted to the House of Representatives, Ninety-Ninth Congress, First Session, December 5, 1985

    International Nuclear Information System (INIS)

    Approval of H.R. 2062 for the formation of the Central Midwest Interstate Low-Level Radioactive Waste Compact will affect the states of Illinois and Kentucky. The House Energy and Commerce Committee reports its findings and supports the concept of regional cooperation in establishing and operating facilities for low-level wastes. The committee report describes the bill's intent, the committee hearings, and cost estimates, which will be minor. There is a section-by-section analysis and discussion of the bill and an analysis of how the bill will change existing nuclear waste disposal law

  4. Granting the consent of the Congress to the Central Interstate Low-Level Radioactive Waste Compact. A report submitted to the House of Representatives, Ninety-Ninth Congress, First Session, December 5, 1985

    International Nuclear Information System (INIS)

    The House Energy and Commerce Commission is favorable to H.R. 1046, which establishes the Central Interstate Low-Level Radioactive Waste Compact for the states of Arkansas, Iowa, Kansas, Louisiana, Minnesota, Missouri, Nebraska, North Dakota, and Oklahoma. The committee report summarizes the bill and its intent, reports on committee hearings and findings concerning the need for regional cooperation in siting waste facilities and incentives to encourage that cooperation, and estimates the cost to the federal government to be minor. There is a section-by-section analysis of the bill, followed by the changes in the 1980 Act the bill entails

  5. Central Stellar Mass Deficits in the Bulges of Local Lenticular Galaxies, and the Connection with Compact z ~ 1.5 Galaxies

    CERN Document Server

    Dullo, Bililign T

    2013-01-01

    We have used the full radial extent of images from the Hubble Space Telescope's Advanced Camera for Surveys and Wide Field Planetary Camera 2 to extract surface brightness profiles from a sample of six, local lenticular galaxy candidates. We have modelled these profiles using a core-Sersic bulge plus an exponential disk model. Our lenticular disk galaxies with bulge magnitudes M_V 10^11 M_sun, and therefore appear to be descendants of the compact galaxies reported at z ~ 1.5 to 2. Past studies which have searched for these local counterparts by using single-component galaxy models to provide the z ~ 0 size comparisons have over-looked these dense, compact and massive bulges in today's early-type disk galaxies. This evolutionary scenario not only accounts for what are today generally old bulges---which must be present in z ~ 1.5 images---residing in what are generally young disks, but it eliminates the uncomfortable suggestion of a factor of 3 to 5 growth in size for the compact, z ~ 1.5 galaxies that are kno...

  6. Development of objective air-mass classifications for studies of heat-related mortality in central Europe and east Asia

    Czech Academy of Sciences Publication Activity Database

    Kyselý, Jan; Kim, J.; Huth, Radan; Choi, B. C.

    Christchurch : Modelling and Simulation Society of Australia and New Zealand, 2007 - (Oxley, L.; Kulasiri, D.), s. 2875-2881 ISBN 978-0-9758400-4-7. [International Congress on Modelling and Simulation. Christchurch (NZ), 10.12.2007-13.12.2007] R&D Projects: GA ČR GC205/07/J044 Institutional research plan: CEZ:AV0Z30420517 Keywords : biometeorology * human mortality * heat stress * air mass classifications * central Europe * east Asia Subject RIV: DG - Athmosphere Sciences, Meteorology

  7. 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.

  8. Is there a divergence between objective measures and subjective perceptions of poverty trends? Evidence from West and Central Africa

    OpenAIRE

    Wodon, Quentin

    2007-01-01

    Several sub-Saharan African countries have succeeded at increasing their economic growth rate in recent years, and this has translated into substantial poverty reduction according to objective measures based on household survey data. At the same time, many people do not feel that the poverty situation has been improving in their country or community, and this is a source of concern for ele...

  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. Relativistic compact objects in isotropic coordinates

    Indian Academy of Sciences (India)

    M K Mak; T Harko

    2005-08-01

    We present a matrix method for obtaining new classes of exact solutions for Einstein's equations representing static perfect fluid spheres. By means of a matrix transformation, we reduce Einstein's equations to two independent Riccati-type differential equations for which three classes of solutions are obtained. One class of the solutions corresponding to the linear barotropic-type fluid with an equation of state = ρ is discussed in detail.

  12. A new model for spherically symmetric anisotropic compact star

    Science.gov (United States)

    Maurya, S. K.; Gupta, Y. K.; Dayanandan, Baiju; Ray, Saibal

    2016-05-01

    In this article we obtain a new anisotropic solution for Einstein's field equations of embedding class one metric. The solution represents realistic objects such as Her X-1 and RXJ 1856-37. We perform a detailed investigation of both objects by solving numerically the Einstein field equations with anisotropic pressure. The physical features of the parameters depend on the anisotropic factor i.e. if the anisotropy is zero everywhere inside the star then the density and pressures will become zero and the metric turns out to be flat. We report our results and compare with the above mentioned two compact objects as regards a number of key aspects: the central density, the surface density onset and the critical scaling behaviour, the effective mass and radius ratio, the anisotropization with isotropic initial conditions, adiabatic index and red shift. Along with this we have also made a comparison between the classical limit and theoretical model treatment of the compact objects. Finally we discuss the implications of our findings for the stability condition in a relativistic compact star.

  13. 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

  14. Objectively measured time spent sedentary is associated with insulin resistance independent of overall and central body fat in 9- to 10-year-old Portuguese children

    DEFF Research Database (Denmark)

    Sardinha, Luis B; Andersen, Lars Bo; Anderssen, Sigmund A;

    2007-01-01

    OBJECTIVE: We examined the independent relationships between objectively measured physical activity and insulin resistance in Portuguese children. RESEARCH DESIGN AND METHODS: This is a school-based, cross-sectional study in 147 randomly selected girls (aged 9.8 +/- 0.3 years; 27.8 +/- 9.3% body......-intensity activity (accelerometer counts >2,001/min). We measured total and central fat mass by dual-energy X-ray absorptiometry. Insulin resistance was expressed as the homeostasis model assessment score. RESULTS: Time (min/day) spent sedentary was significantly and positively associated with insulin resistance...... (beta-coefficient = 0.001 [95% CI 0.0002-0.002]; P = 0.013). Time spent in moderate- and vigorous-intensity physical activity (-0.002 [-0.003 to -0.001]; P = 0.0009) and overall physical activity (-0.001 [-0.008 to 0.003]; P < 0.0001) were significantly and inversely associated with insulin resistance...

  15. 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 ...

  16. Compact stars in alternative theories of gravity: Einstein-Dilaton-Gauss-Bonnet gravity

    International Nuclear Information System (INIS)

    We develop a theoretical framework to study slowly rotating compact stars in a rather general class of alternative theories of gravity, with the ultimate goal of investigating constraints on alternative theories from electromagnetic and gravitational-wave observations of compact stars. Our Lagrangian includes as special cases scalar-tensor theories (and indirectly f(R) theories) as well as models with a scalar field coupled to quadratic curvature invariants. As a first application of the formalism, we discuss (for the first time in the literature) compact stars in Einstein-Dilaton-Gauss-Bonnet gravity. We show that compact objects with central densities typical of neutron stars cannot exist for certain values of the coupling constants of the theory. In fact, the existence and stability of compact stars sets more stringent constraints on the theory than the existence of black hole solutions. This work is a first step in a program to systematically rule out (possibly using Bayesian model selection) theories that are incompatible with astrophysical observations of compact stars.

  17. Compact balanced tries

    OpenAIRE

    Nicodeme, Pierre

    1991-01-01

    We show how it is possible to split Compact Tries described as bit-lists in a segmented and flexible structure of B-tree type, keeping the compactness advantages of the Compact Tries and recovering all the important properties of B-trees.

  18. The classification of p-compact groups for p odd

    DEFF Research Database (Denmark)

    Andersen, K.K.S.; Grodal, J.; Møller, J. M.;

    2008-01-01

    A p-compact group, as defined by Dwyer and Wilkerson, is a purely homotopically defined p-local analog of a compact Lie group. It has long been the hope, and later the conjecture, that these objects should have a classification similar to the classification of compact Lie groups. In this paper we...

  19. A survey of Low Luminosity Compact sources

    CERN Document Server

    Kunert-Bajraszewska, Magdalena

    2009-01-01

    Based on the FIRST and SDSS catalogues a flux density limited sample of weak Compact Steep Spectrum (CSS) sources with radio luminosity below 10^26 [W/Hz] at 1.4 GHz has been constructed. Our previous multifrequency observations of CSS sources have shown that low luminosity small-scale objects can be strong candidates for compact faders. This finding supports the idea that some small-size radio sources are short-lived phenomena because of a lack of significant fuelling. They never 'grow up' to become FRI or FRII objects. This new sample marks the start of a systematical study of the radio properties and morphologies of the population of low luminosity compact (LLC) objects. An investigation of this new sample should also lead to a better understanding of compact faders. In this paper, the results of the first stage of the new project - the L-band MERLIN observations of 44 low luminosity CSS sources are presented.

  20. A new model for spherically symmetric anisotropic compact star

    CERN Document Server

    Maurya, S K; Dayanandan, Baiju; Ray, Saibal

    2016-01-01

    In this article we obtain a new anisotropic solution for Einstein's field equation of embedding class one metric. The solution is representing the realistic objects such as $Her~X-1$ and $RXJ~1856-37$. We perform detailed investigation of both objects by solving numerically the Einstein field equations under with anisotropic pressure. The physical features of the parameters depend on the anisotropic factor i.e. if anisotropy is zero everywhere inside the star then the density and pressures will become zero and metric turns out to be flat. We report our results and compare with the above mentioned two compact objects on a number of key aspects: the central density, the surface density onset and the critical scaling behavior, the effective mass and radius ratio, the anisotropization with isotropic initial conditions, adiabatic index and red shift. Along with this we have also made a comparison between the classical limit and theoretical model treatment of the compact objects. Finally we discuss the implications...

  1. Cooling of Compact Stars with Color Superconducting Quark Matter

    CERN Document Server

    Noda, Tsuneo; Hashimoto, Masa-aki; Maruyama, Toshiki; Tatsumi, Toshitaka; Fujimoto, Masayuki Y

    2015-01-01

    We show a scenario for the cooling of compact stars considering the central source of Cassiopeia A (Cas A). The Cas A observation shows that the central source is a compact star with high effective temperature, and it is consistent with the cooling without exotic phases. The Cas A observation also gives the mass range of $M \\geq 1.5 M_\\odot$. It may conflict with the current cooling scenarios of compact stars that heavy stars show rapid cooling. We include the effect of the color superconducting (CSC) quark matter phase on the thermal evolution of compact stars. We assume the gap energy of CSC quark phase is large ($\\Delta \\gtrsim \\mathrm{10 MeV}$), and we simulate the cooling of compact stars. We present cooling curves obtained from the evolutionary calculations of compact stars: while heavier stars cool slowly, and lighter ones indicate the opposite tendency.

  2. 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.

  3. 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

  4. Object and Objective Lost?

    DEFF Research Database (Denmark)

    Lopdrup-Hjorth, Thomas

    2015-01-01

    of this organization-phobia, the paper argues that OT has become increasingly incapable of speaking about its core object. I show how organizations went from being conceptualized as entities of major importance to becoming theoretically deconstructed and associated with all kinds of ills. Through this history...

  5. Compact stellarator coils

    International Nuclear Information System (INIS)

    Experimental devices to study the physics of high-beta (β>∼4%), low aspect ratio (A<∼4.5) stellarator plasmas require coils that will produce plasmas satisfying a set of physics goals, provide experimental flexibility, and be practical to construct. In the course of designing a flexible coil set for the National Compact Stellarator Experiment, we have made several innovations that may be useful in future stellarator design efforts. These include: the use of Singular Value Decomposition methods for obtaining families of smooth current potentials on distant coil winding surfaces from which low current density solutions may be identified; the use of a Control Matrix Method for identifying which few of the many detailed elements of the stellarator boundary must be targeted if a coil set is to provide fields to control the essential physics of the plasma; the use of Genetic Algorithms for choosing an optimal set of discrete coils from a continuum of potential contours; the evaluation of alternate coil topologies for balancing the tradeoff between physics objective and engineering constraints; the development of a new coil optimization code for designing modular coils, and the identification of a 'natural' basis for describing current sheet distributions. (author)

  6. 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

    Finding ways for developing countries with tropical forests to participate more effectively in international efforts to reduce greenhouse gas (GHG) emissions has become central to the success of any future international agreement. The most obvious means would be the reduction of tropical deforestation and the emissions associated with it. Unless tropical deforestation is reduced it will not be possible to avoid 'dangerous anthropogenic interference' in the planet's climate. In this chapter the necessary conditions for these countries to use reduced deforestation, in the context of 'compensated reduction of deforestation', as an internationally recognized, valid form of mitigation of global climate change and, in return, receive compensation for demonstrated reductions. The proposal for compensated reduction suggests that countries that reduce their emissions from tropical deforestation during a Kyoto Protocol commitment period, in relation to an agreed baseline in accordance with historical deforestation rates, be remunerated with credits equivalent to the volume of emissions avoided, tradable in subsequent commitment periods. As we know, under the current terms of the Kyoto Protocol, covering the first commitment period, there are no means to offer incentives for reducing deforestation, which are a recognized factor in global emissions (25%). Eligible forestry projects in the Clean Development Mechanism (CDM) include only carbon sequestration. Since tropical deforestation is a problem occurring in non-Annex 1 developing countries, and is associated with development strategies historically linked to global markets, international instruments to encourage reduction of deforestation emissions should consider the objective conditions of these countries in a manner consistent with the principle of mutual, but differentiated responsibilities. The compensated reduction proposal emerges in this context: more effective participation of these

  7. Location of gamma-ray Flare Emission in the Jet of the BL Lacertae Object OJ287 more than 14pc from the Central Engine

    CERN Document Server

    Agudo, Ivan; Marscher, Alan P; Larionov, Valeri M; Gomez, Jose L; Lahteenmaki, Anne; Gurwell, Mark A; Smith, Paul S; Wiesemeyer, Helmut; Thum, Clemens; Heidt, Jochen; Blinov, Dmitriy A; D'Arcangelo, Francesca D; Hagen-Thorn, Vladimir A; Morozova, Daria A; Nieppola, Elina; Roca-Sogorb, Mar; Schmidt, Gary D; Taylor, Brian; Tornikoski, Merja; Troitsky, Ivan S

    2010-01-01

    We combine time-dependent multi-waveband flux and linear polarization observations with sub-milliarcsecond-scale polarimetric images at lambda=7mm of the BL Lacertae-type blazar OJ287 to locate the gamma-ray emission in prominent flares in the jet of the source >14pc from the central engine. We demonstrate a highly significant correlation between the strongest gamma-ray and millimeter-wave flares through Monte-Carlo simulations. The two reported gamma-ray peaks occurred near the beginning of two major mm-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Our Very Long Baseline Array observations indicate that the two mm-wave flares originated in the second of two features in the jet that are separated by >14 pc. The simultaneity of the peak of the higher-amplitude gamma-ray flare and the maximum in polarization of the second jet feature implies that the gamma-ray and mm-wave flares are co-spatial and occur >14 pc from the central engine. We also associate...

  8. Compact stellar systems in the Fornax cluster: a UV perspective

    CERN Document Server

    Mieske, Steffen; Bomans, Dominik J; Rey, Soo-Chang; Kim, Suk; Yoon, Suk-Jin; Chung, Chul

    2008-01-01

    In recent years, increasing evidence for chemical complexity and multiple stellar populations in massive globular clusters (GCs) has emerged, including extreme horizontal branches (EHBs) and UV excess. Our goal is to improve our understanding of UV excess in the regime of both massive GCs and ultra-compact dwarf galaxies (UCDs). To this end, we use deep archival GALEX data of the central Fornax cluster to measure NUV and FUV magnitudes of UCDs and massive GCs. We obtain NUV photometry for a sample of 35 compact objects with -13.5objects also have FUV photometry. Roughly half of the sources fall into the UCD luminosity regime (M_V <=-11 mag). We find that seven out of 17 massive Fornax GCs exhibit a NUV excess with respect to expectations from stellar population models, even for models with enhanced Helium abundance. This suggests that not only He-enrichment has contributed to forming the EHB population of these GCs. The GCs extend to stronger UV excess than GCs in M31 and m...

  9. Measurement of the abundance of stellar mass compact objects in the galactic halo by detecting micro-lenses in the Large Magellanic Cloud; Mesure de l'abondance des astres sombres de masse stellaire dans le halo galactique par la recherche de phenomenes de microlentilles vers les nuages de magellan

    Energy Technology Data Exchange (ETDEWEB)

    Lasserre, Th

    2000-05-09

    Many experimental and theoretical results lead to the conclusion that at least 80 percent of the mass of our Galaxy is dark. Part of this so-called dark matter could be in the form of stellar mass compact objects, called MACHOS; these could be detected using the gravitational microlensing effect. The first generation experiments EROS1 and MACHO have strongly constrained the galactic abundance of objects lighter than 0.01 solar mass to less than 10 percent of the total mass. In parallel, the observation by the MACHO group of massive candidates (half the Sun's mass), numerous enough to constitute 50 percent of galactic dark matter, was a further motivation for the EROS group to extend this search to stellar mass objects in a second phase, EROS2. The present work deals with the analysis of 25 million stellar light curves in the Large Magellanic Cloud, observed for three years in order to extract the rare microlensing candidates and to measure the galactic halo mass fraction in the form of compact objects. After recalling the motivations of this search and the theoretical context, I describe the EROS2 experiment. The observational strategy and the photometric reduction procedures needed to deal with the 1.2 To of data are then presented. A new method to detect micro-lenses is detailed, as well as a discussion of background light curves, poorly known. We do not find enough microlensing candidates to explain the galactic rotation curve; this confirms, and improve on previous EROS1 and EROS2 results. Combining all results from EROS allows to exclude that MACHOS with a mass between 10 e-7 and 10 solar mass are important constituents of the galactic halo. This statement agrees with recent results from the MACHO group, although our interpretations differ, namely on the topics of the location of the lenses, and of a possible contamination of the microlensing ample by background phenomena. (author)

  10. 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.

  11. LOCATION OF γ-RAY FLARE EMISSION IN THE JET OF THE BL LACERTAE OBJECT OJ287 MORE THAN 14 pc FROM THE CENTRAL ENGINE

    International Nuclear Information System (INIS)

    We combine time-dependent multi-waveband flux and linear polarization observations with submilliarcsecond-scale polarimetric images at λ = 7 mm of the BL Lacertae type blazar OJ287 to locate the γ-ray emission in prominent flares in the jet of the source >14 pc from the central engine. We demonstrate a highly significant correlation between the strongest γ-ray and millimeter-wave flares through Monte Carlo simulations. The two reported γ-ray peaks occurred near the beginning of two major millimeter-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Our very long baseline array observations indicate that the two millimeter-wave flares originated in the second of two features in the jet that are separated by >14 pc. The simultaneity of the peak of the higher-amplitude γ-ray flare and the maximum in polarization of the second jet feature implies that the γ-ray and millimeter-wave flares are cospatial and occur >14 pc from the central engine. We also associate two optical flares, accompanied by sharp polarization peaks, with the two γ-ray events. The multi-waveband behavior is most easily explained if the γ-rays arise from synchrotron self-Compton scattering of optical photons from the flares. We propose that flares are triggered by interaction of moving plasma blobs with a standing shock. The γ-ray and optical emission is quenched by inverse Compton losses as synchrotron photons from the newly shocked plasma cross the emission region. The millimeter-wave polarization is high at the onset of a flare, but decreases as the electrons emitting at these wavelengths penetrate less polarized regions.

  12. 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.

  13. AN OBJECT-BASED WORKFLOW DEVELOPED TO EXTRACT AQUACULTURE PONDS FROM AIRBORNE LIDAR DATA: A TEST CASE IN CENTRAL VISAYAS, PHILIPPINES

    OpenAIRE

    Loberternos, R. A.; Porpetcho, W. P.; Graciosa, J. C. A.; Violanda, R. R.; Diola, A. G.; Dy, D. T.; Otadoy, R. E. S.

    2016-01-01

    Traditional remote sensing approach for mapping aquaculture ponds typically involves the use of aerial photography and high resolution images. The current study demonstrates the use of object-based image processing and analyses of LiDAR-data-generated derivative images with 1-meter resolution, namely: CHM (canopy height model) layer, DSM (digital surface model) layer, DTM (digital terrain model) layer, Hillshade layer, Intensity layer, NumRet (number of returns) layer, and Slope layer. A Cann...

  14. A compact THz imaging system

    Science.gov (United States)

    Sešek, Aleksander; Å vigelj, Andrej; Trontelj, Janez

    2015-03-01

    The objective of this paper is the development of a compact low cost imaging THz system, usable for observation of the objects near to the system and also for stand-off detection. The performance of the system remains at the high standard of more expensive and bulkiest system on the market. It is easy to operate as it is not dependent on any fine mechanical adjustments. As it is compact and it consumes low power, also a portable system was developed for stand-off detection of concealed objects under textile or inside packages. These requirements rule out all optical systems like Time Domain Spectroscopy systems which need fine optical component positioning and requires a large amount of time to perform a scan and the image capture pixel-by-pixel. They are also almost not suitable for stand-off detection due to low output power. In the paper the antenna - bolometer sensor microstructure is presented and the THz system described. Analysis and design guidelines for the bolometer itself are discussed. The measurement results for both near and stand-off THz imaging are also presented.

  15. 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.

  16. 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 ...

  17. 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.

  18. 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

  19. A large population of ultra-compact dwarf galaxies in the Hydra I cluster

    CERN Document Server

    Misgeld, I; Hilker, M; Richtler, T; Georgiev, I Y; Schuberth, Y

    2011-01-01

    We performed a large spectroscopic survey of compact, unresolved objects in the core of the Hydra I galaxy cluster (Abell 1060), with the aim of identifying ultra-compact dwarf galaxies (UCDs), and investigating the properties of the globular cluster (GC) system around the central cD galaxy NGC 3311. We obtained VIMOS medium resolution spectra of about 1200 candidate objects with apparent magnitudes 18.5 5 x 10^7 M_sun) and a half-light radius of 25 pc. This places it among the brightest and most massive UCDs ever discovered. Most of the GCs/UCDs are both spatially and dynamically associated to the central cD galaxy. The overall velocity dispersion of the GCs/UCDs is comparable to what is found for the cluster galaxies. However, when splitting the sample into a bright and a faint part, we observe a lower velocity dispersion for the bright UCDs/GCs than for the fainter objects. At a dividing magnitude of M_V = -10.75 mag, the dispersions differ by more than 200 km/s, and up to 300 km/s for objects within 5 ar...

  20. Super compacting of drums with dry solid radioactive waste in the nuclear power plant of Laguna Verde;Super compactacion de bidones con desecho radiactivo solido seco en la central nucleo electrica Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez G, R.; Lara H, M. A.; Cabrera Ll, M.; Verdalet de la Torre, O., E-mail: marco.lara@cfe.gob.m [Comision Federal de Electricidad, Central Nucleoelectrica de Laguna Verde, Carretera Nautla-Cardel Km. 42.5, Alto Lucero, Veracruz (Mexico)

    2009-10-15

    The nuclear power plant of Laguna Verde located in the Gulf of Mexico, completes in this 2009, nineteen years to produce by nuclear means 4.78% of the electric power that Mexico requires daily. During this time, the Unit 1 has generated more of 88.85 million mega watt-hour and the Unit 2 more of 69.48 million mega watt-hour with an availability average of 83.55%. Derived of their operation cycles, the nuclear power plant has generated (as any other installation of its type) radioactive wastes of low activity that at the moment are temporarily stored in the site. Due to the life cycle of the nuclear power plant, actually has become necessary to begin a project series focused to continue guaranteeing the storage of these wastes, guarantee that is a license requirement for the operation of this nuclear installation before the National Commission of Nuclear Security and Safeguards. The Federal Commission of Electricity beginning a project that allows continue guaranteeing space of sufficient storage for the wastes that the nuclear power plant of Laguna Verde could generate for the rest of its useful life, this project consisted on a process of physical volume reduction of dry solid radioactive wastes denominated super compacting, it has made possible to reduce the volume that these wastes occupy in the temporary storage noted Dry Solid Radioactive Wastes Deposit located inside the site that occupies the nuclear power plant of Laguna Verde. This work presents the super compacting results, as well as a description of the realization of this task until concluding with the super compacting of 5,854 drums with dry solid radioactive waste of low activity. We will enunciate which were the radiological controls that the Department of Radiological Protection of the nuclear power plant of Laguna Verde applied to this work that was realized for first time in Mexico and the nuclear power plant. (Author)

  1. An objective method for the assessment of fluid injection-induced seismicity and application to tectonically active regions in central California

    Science.gov (United States)

    Goebel, T. H. W.; Hauksson, E.; Aminzadeh, F.; Ampuero, J.-P.

    2015-10-01

    Changes in seismicity rates, whether of tectonic or of induced origin, can readily be identified in regions where background rates are low but are difficult to detect in seismically active regions. We present a novel method to identify likely induced seismicity in tectonically active regions based on short-range spatiotemporal correlations between changes in fluid injection and seismicity rates. The method searches through the entire parameter space of injection rate thresholds and determines the statistical significance of correlated changes in injection and seismicity rates. Applying our method to Kern County, central California, we find that most earthquakes within the region are tectonic; however, fluid injection contributes to seismicity in four different cases. Three of these are connected to earthquake sequences with events above M4. Each of these sequences followed an abrupt increase in monthly injection rates of at least 15,000 m3. The probability that the seismicity sequences and the abrupt changes in injection rates in Kern County coincide by chance is only 4%. The identified earthquake sequences display low Gutenberg-Richter b values of ˜0.6-0.7 and at times systematic migration patterns characteristic for a diffusive process. Our results show that injection-induced pressure perturbations can influence seismic activity at distances of 10 km or more. Triggering of earthquakes at these large distances may be facilitated by complex local geology and faults in tectonically active regions. Our study provides the first comprehensive, statistically robust assessment of likely injection-induced seismicity within a large, tectonically active region.

  2. Objective assessment of utility of intraoperative ultrasound in resection of central nervous system tumors: A cost-effective tool for intraoperative navigation in neurosurgery

    Directory of Open Access Journals (Sweden)

    Aliasgar Moiyadi

    2011-01-01

    Full Text Available Background: Localization and delineation of extent of lesions is critical for safe maximal resection of brain and spinal cord tumors. Frame-based and frameless stereotaxy and intraoperative MRI are costly and not freely available especially in economically constrained nations. Intraoperative ultrasound has been around for a while but has been relegated to the background. Lack of objective evidence for its usefulness and the perceived "user unfriendliness" of US are probably responsible for this. We recount our experience with this "forgotten" tool and propose an objective assessment score of its utility in an attempt to revive this practice. Materials and Methods: Seventy seven intraoperative ultrasound (IOUS studies were carried out in patients with brain and spinal cord tumors. Seven parameters were identified to measure the "utility" of the IOUS and a "utility score" was devised (minimum 0 and maximum 7. Individual parameter and overall scores were calculated for each case. Results: IOUS was found to be useful in many ways. The median overall score was 6 (mean score 5.65. There were no scores less than 4 with the majority demonstrating usefulness in 5 or more parameters (91%. The use of the IOUS significantly influenced the performance of the surgery in these cases without significantly prolonging surgery. Conclusions: The IOUS is a very useful tool in intraoperative localization and delineation of lesions and planning various stages of tumor resection. It is easy, convenient, reliable, widely available, and above all a cost-effective tool. It should be increasingly used by neurosurgeons in the developing world where costlier intraoperative localization and imaging is not available freely.

  3. Analisis Risk Assessment Menggunakan Process Hazard Analysis (PHA dan Safety Objective Analysis (SOA pada Central Gathering Station (CGS di Onshore Facilities

    Directory of Open Access Journals (Sweden)

    Dimas Jouhari

    2014-03-01

    Full Text Available Keselamatan proses merupakan faktor utama yang sering dibahas oleh industri-industri kimia beberapa tahun terakhir ini. Salah satu metode semi-kuantitatif yang dapat digunakan untuk mengidentifikasi, menganalisis, dan menetapkan tingkat risiko bahaya yaitu dengan Process Hazard Analysis (PHA dan Safety Objective Analysis (SOA. Hazard and Operability Studies (HAZOP dan What-If Analysis merupakan metode identifikasi bahaya kualitatif yang sering diterapkan secara simultan untuk PHA-SOA. Process Hazard Analysis (PHA ialah rangkaian aktivitas mengidentifikasi hazard, mengestimasi konsekuensi, mengestimasi likelihood suatu skenario proses disertai dengan safeguard, dan mendapatkan risk ranking yang dapat dilihat pada matrik PHA 6x6. Sedangkan Safety Objective Analysis (SOA merupakan rangkaian aktivitas yang bergantung pada penyebab skenario, dan konsekuensi dari PHA, menghasilkan kebutuhan IPL (Independent Protective Layer menggunakan matrik SOA 6x6. Risk ranking 6 pada penilaian PHA diketegorikan aman jika safeguard yang ada selalu siap mengurangi risiko yang timbul dari skenario tersebut. Namun tidak semua safeguard dapat selalu siap mengurangi risiko tersebut. Oleh karena itu, perlu adanya analisis tambahan untuk memastikan risiko dari skenario dapat diperkecil. Analisis safety suatu skenario dengan SOA menghasilkan kebutuhan IPL yang dapat ditutup dengan mengkonfirmasi safeguard yang sesuai menjadi IPL. Hasil penilaian PHA-SOA CGS 1, CGS 3, CGS 4, dan CGS 5 menunjukkan bahwa ada penilaian severity dan PHA-SOA likelihood yang berbeda di tiap CGS padahal proses pada CGS tersebut identik, maka perlu adanya analisis konsistensi. Hasil analisis konsistensi ini dapat dijadikan pedoman untuk melakukan safety review pada risk assessment workshop kedepannya, yang biasanya diadakan setiap tiga hingga lima tahun sekali oleh industri.

  4. An Object-Based Workflow Developed to Extract Aquaculture Ponds from Airborne LIDAR Data: a Test Case in Central Visayas, Philippines

    Science.gov (United States)

    Loberternos, R. A.; Porpetcho, W. P.; Graciosa, J. C. A.; Violanda, R. R.; Diola, A. G.; Dy, D. T.; Otadoy, R. E. S.

    2016-06-01

    Traditional remote sensing approach for mapping aquaculture ponds typically involves the use of aerial photography and high resolution images. The current study demonstrates the use of object-based image processing and analyses of LiDAR-data-generated derivative images with 1-meter resolution, namely: CHM (canopy height model) layer, DSM (digital surface model) layer, DTM (digital terrain model) layer, Hillshade layer, Intensity layer, NumRet (number of returns) layer, and Slope layer. A Canny edge detection algorithm was also performed on the Hillshade layer in order to create a new image (Canny layer) with more defined edges. These derivative images were then used as input layers to perform a multi-resolution segmentation algorithm best fit to delineate the aquaculture ponds. In order to extract the aquaculture pond feature, three major classes were identified for classification, including land, vegetation and water. Classification was first performed by using assign class algorithm to classify Flat Surfaces to segments with mean Slope values of 10 or lower. Out of these Flat Surfaces, assign class algorithm was then performed to determine Water feature by using a threshold value of 63.5. The segments identified as Water were then merged together to form larger bodies of water which comprises the aquaculture ponds. The present study shows that LiDAR data coupled with object-based classification can be an effective approach for mapping coastal aquaculture ponds. The workflow currently presented can be used as a model to map other areas in the Philippines where aquaculture ponds exist.

  5. Compact toroid fueling for ITER

    International Nuclear Information System (INIS)

    Experimental and theoretical work indicates that deep fueling of ITER may be possible by Compact Toroid (CT) injection. CT velocities sufficient for center fueling of a reactor have been demonstrated in the RACE device. CT injections into the TdeV tokamak have achieved central penetration at 1.4 T, and have increased the particle inventory by more than 30% without disruption. Tests on the MARAUDER device have achieved CT mass-densities suitable for injection into 5 T tokamaks. Techniques for producing multiple-shot CT's with passive electric switching are being tested on CTIX. The advantages of deep fueling by CT injection include profile peaking to reach ignition, profile control, low tritium inventory and others. In this paper, the CT experimental results are summarized, a conceptual design of a CT fueler for ITER is presented, and the implications on ITER operation and fuel cycle are discussed. 16 refs., 2 figs., 1 tab

  6. Strategy Guideline: Compact Air Distribution Systems

    Energy Technology Data Exchange (ETDEWEB)

    Burdick, A.

    2013-06-01

    This Strategy 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. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. 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.

  7. Physics design of a compact medical cyclotron

    International Nuclear Information System (INIS)

    Background: A compact cyclotron with energy of 11 MeV and current of 50 μA is under construction in Institute of Fluid Physics of China Academy of Engineering Physics. The compact cyclotron is developed for medical isotope production. Purpose: To minimize the cost and to shorten the time of the development of the compact cyclotron, a lot of efforts were dedicated to the physics design of the compact cyclotron. Methods: Physics design of the main magnet was performed using TOSCA software, and start-to-end beam dynamics design was performed using home-made software CYCDYN. Results: Physics design of the compact cyclotron was given in details. Design methods and results of the main subsystems (including ion source, radial sector focusing magnet, RF cavity, central region and extraction system) were also given in this paper. Conclusion: Now commissioning of this cyclotron has been finished, and the goal for extracting proton beams of 11 MeV and 50 μA on average has been achieved. Physics design of the cyclotron has been validated by the commissioning results. (authors)

  8. Compact stellar X-ray sources

    NARCIS (Netherlands)

    W.H.G. Lewin; M. van der Klis

    2006-01-01

    X-ray astronomy is the prime available window on astrophysical compact objects: black holes, neutron stars and white dwarfs. In the last ten years new observational opportunities have led to an explosion of knowledge in this field. This book provides a comprehensive overview of the astrophysics of c

  9. Toward an object-based assessment of high-resolution forecasts of long-lived convective precipitation in the central U.S.

    Science.gov (United States)

    Bytheway, Janice L.; Kummerow, Christian D.

    2015-09-01

    Forecast models have seen vast improvements in recent years, via both increased resolutions and the ability to assimilate observational data, particularly that which has been affected by clouds and precipitation. The High-Resolution Rapid Refresh (HRRR) model is an hourly updated, 3 km model designed for forecasting convective precipitation recently deployed for operational use over the U.S. that initializes latent heating profiles as a function of assimilated radar reflectivity. An object-oriented verification process was developed to validate experimental HRRR convective precipitation forecasts during the 2013 warm season using the NCEP Stage IV multisensor precipitation product. A database of 467 convective precipitation features that were observed during the forecast assimilation period and their corresponding HRRR forecast precipitation features was created. This database was used to evaluate model performance over the entire forecast period, and to relate that performance to model processes, especially those related to precipitation production. Generally, HRRR precipitation is located within 30 km of the observed throughout the forecast period. Validation statistics are best at forecast hour 3, with median biases in mean, maximum, and total rainfall and raining area near 0%. Earlier in the forecast, median biases in the mean and maximum rain rate exceed 30%, with bias values often exceeding 150%. The median bias in areal extent at the beginning of the forecast is near -40%. This low areal bias and POD values <0.6 appear to be related to the model's ability to produce deep convection relative to atmospheric moisture content and concentration of rainfall in convective cores.

  10. Peat compaction in deltas : implications for Holocene delta evolution

    NARCIS (Netherlands)

    van Asselen, S.

    2010-01-01

    Many deltas contain substantial amounts of peat, which is the most compressible soil type. Therefore, peat compaction potentially leads to high amounts of subsidence in deltas. The main objective of this research was to quantify subsidence due to peat compaction in Holocene fluvial-deltaic settings

  11. Iterative solution of high order compact systems

    Energy Technology Data Exchange (ETDEWEB)

    Spotz, W.F.; Carey, G.F. [Univ. of Texas, Austin, TX (United States)

    1996-12-31

    We have recently developed a class of finite difference methods which provide higher accuracy and greater stability than standard central or upwind difference methods, but still reside on a compact patch of grid cells. In the present study we investigate the performance of several gradient-type iterative methods for solving the associated sparse systems. Both serial and parallel performance studies have been made. Representative examples are taken from elliptic PDE`s for diffusion, convection-diffusion, and viscous flow applications.

  12. Production of Self-Compacting Concrete

    OpenAIRE

    DE LARRARD, F; Cazacliu, B.; CHATEAU, E

    2003-01-01

    This paper presents a summary of recent research carried out at LCPC, Nantes (France), dealing with the controlled production of high-performance and self-compacting concrete. The question of precision of water dosage is first investigated, through an experimental program where a variety of sensors were calibrated, tested and compared. Then, emphasis is put on the power consumption curve of mixers. This classical tool in central-batched concrete production can be treated in a more scientific ...

  13. 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.

  14. Hydraulic Conductivity of Compacted Laterite Treated with Iron Ore Tailings

    OpenAIRE

    Yusuf, Umar Sa’eed; Slim, Matawal Danladi; Uchechukwu, Elinwa Augustine

    2016-01-01

    The objective of this study was to investigate the effect of iron ore tailings (IOT) on hydraulic conductivity of compacted laterite. The IOT conforms to ASTM C 618-15 Type F designations. In the present study, soil was admixed with 0–20% IOT and compacted at moulding water content ranging from 10 to 25% using four types of compactive efforts. Hydraulic conductivities of the compacted soil-IOT mixtures were determined using deionized water and municipal solid waste leachate as the permeant fl...

  15. An extended star formation history in an ultra-compact dwarf

    Science.gov (United States)

    Norris, Mark A.; Escudero, Carlos G.; Faifer, Favio R.; Kannappan, Sheila J.; Forte, Juan Carlos; van den Bosch, Remco C. E.

    2015-08-01

    There has been significant controversy over the mechanisms responsible for forming compact stellar systems like ultra-compact dwarfs (UCDs), with suggestions that UCDs are simply the high-mass extension of the globular cluster population, or alternatively, the liberated nuclei of galaxies tidally stripped by larger companions. Definitive examples of UCDs formed by either route have been difficult to find, with only a handful of persuasive examples of stripped-nucleus-type UCDs being known. In this paper, we present very deep Gemini/GMOS spectroscopic observations of the suspected stripped-nucleus UCD NGC 4546-UCD1 taken in good seeing conditions (<0.7 arcsec). With these data we examine the spatially resolved kinematics and star formation history of this unusual object. We find no evidence of a rise in the central velocity dispersion of the UCD, suggesting that this UCD lacks a massive central black hole like those found in some other compact stellar systems, a conclusion confirmed by detailed dynamical modelling. Finally, we are able to use our extremely high signal-to-noise spectrum to detect a temporally extended star formation history for this UCD. We find that the UCD was forming stars since the earliest epochs until at least 1-2 Gyr ago. Taken together these observations confirm that NGC 4546-UCD1 is the remnant nucleus of a nucleated dwarf galaxy that was tidally destroyed by NGC 4546 within the last 1-2 Gyr.

  16. The effect of adaptive servo ventilation (ASV) on objective and subjective outcomes in Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF): A systematic review.

    Science.gov (United States)

    Yang, Hyunju; Sawyer, Amy M

    2016-01-01

    To summarize the current evidence for adaptive servo ventilation (ASV) in Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF) and advance a research agenda and clinical considerations for ASV-treated CSR-CSA in HF. CSR-CSA in HF is associated with higher overall mortality, worse outcomes and lower quality of life (QOL) than HF without CSR-CSA. Five databases were searched using key words (n = 234). Randomized controlled trials assessed objective sleep quality, cardiac, and self-reported outcomes in adults (≥18 years) with HF (n = 10). ASV has a beneficial effect on the reduction of central sleep apnea in adult patients with CSR-CSA in HF, but it is not be superior to CPAP, bilevel PPV, or supplemental oxygen in terms of sleep quality defined by polysomnography, cardiovascular outcomes, subjective daytime sleepiness, and quality of life. ASV is not recommended for CSR-CSA in HF. It is important to continue to refer HF patients for sleep evaluation to clearly discern OSA from CSR-CSA. Symptom management research, inclusive of objective and subjective outcomes, in CSR-CSA in HF adults is needed. PMID:26995256

  17. Compact fusion reactors

    International Nuclear Information System (INIS)

    Compact, high-power-density approaches to fusion power are proposed to improve economic viability through the use of less-advanced technology in systems of considerably reduced scale. The rationale for and the means by which these systems can be achieved are discussed, as are unique technological problems

  18. Limestone compaction: an enigma

    Science.gov (United States)

    Shinn, Eugene A.; Halley, Robert B.; Hudson, J. Harold; Lidz, Barbara H.

    1977-01-01

    Compression of an undisturbed carbonate sediment core under a pressure of 556 kg/cm2 produced a “rock” with sedimentary structures similar to typical ancient fine-grained limestones. Surprisingly, shells, foraminifera, and other fossils were not noticeably crushed, which indicates that absence of crushed fossils in ancient limestones can no longer be considered evidence that limestones do not compact.

  19. 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.

  20. G313.3+00.3: A New Planetary Nebula discovered by the Australia Telescope Compact Array and the Spitzer Space Telescope

    OpenAIRE

    Cohen, Martin; Green, Anne J.; Roberts, Mallory S. E.; Meade, Marilyn R.; Babler, Brian; Indebetouw, Remy; Whitney, Barbara A.; Watson, Christer; Wolfire, Mark; Wolff, Mike J.; Mathis, John S.; Churchwell, Edward B.

    2005-01-01

    We present a new planetary nebula, first identified in images from the Australia Telescope Compact Array, although not recognized at that time. Recent observations with the Spitzer Space Telescope during the GLIMPSE Legacy program have rediscovered the object. The high-resolution radio and infrared images enable the identification of the central star or its wind, the recognition of the radio emission as thermal, and the probable presence of polycylic aromatic hydrocarbons in and around the so...

  1. 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.

  2. SHORT GAMMA-RAY BURSTS FROM DYNAMICALLY ASSEMBLED COMPACT BINARIES IN GLOBULAR CLUSTERS: PATHWAYS, RATES, HYDRODYNAMICS, AND COSMOLOGICAL SETTING

    International Nuclear Information System (INIS)

    We present a detailed assessment of the various dynamical pathways leading to the coalescence of compact objects in globular clusters (GCs) and Short Gamma-ray Burst (SGRB) production. We consider primordial binaries, dynamically formed binaries (through tidal two-body and three-body exchange interactions), and direct impacts of compact objects (WD/NS/BH). Here, we show that if the primordial binary fraction is small, close encounters dominate the production rate of coalescing compact systems. We find that the two dominant channels are the interaction of field neutron stars (NSs) with dynamically formed binaries and two-body encounters. Under such conditions, we estimate the redshift distribution and host galaxy demographics of SGRB progenitors, and find that GCs can provide a significant contribution to the overall observed rate. Regarding the newly identified channel of close stellar encounters involving WD/NS/BH, we have carried out precise modeling of the hydrodynamical evolution, giving us a detailed description of the resulting merged system. Our calculations show that there is in principle no problem in accounting for the global energy budget of a typical SGRB. The particulars of each encounter, however, are variable in several aspects and can lead to interesting diversity. First and most importantly, the characteristics of the encounter are highly dependent on the impact parameter. This is in contrast to the merger scenario, where the masses of the compact objects dictate a typical length and luminosity scale for SGRB activity. Second, the nature of the compact star itself can produce very different outcomes. Finally, the presence of tidal tails in which material will fall back onto the central object at a later time is a robust feature of the present set of calculations. The mass involved in these structures is considerably larger than for binary mergers. It is thus possible to account generically in this scenario for a prompt episode of energy release, as

  3. The fate of fallback matter around newly born compact objects

    CERN Document Server

    Perna, Rosalba; Cantiello, Matteo; MacFadyen, Andrew

    2013-01-01

    The presence of fallback disks around young neutron stars has been invoked over the years to explain a large variety of phenomena. Here we perform a numerical investigation of the formation of such disks during a supernova explosion, considering both neutron star (NS) and black hole (BH) remnants. Using the public code MESA, we compute the angular momentum distribution of the pre-supernova material, for stars with initial masses M in the range 13 - 40 Msun, initial surface rotational velocities vsurf between 25% and 75% of the critical velocity, and for metallicities Z of 1%, 10% and 100% of the solar value. These pre SN models are exploded with energies E varying between 10^{50} - 3x10^{52} ergs, and the amount of fallback material is computed. We find that, if magnetic torques play an important role in angular momentum transport, then fallback disks around NSs, even for low-metallicity main sequence stars, are not an outcome of SN explosions. Formation of such disks around young NSs can only happen under th...

  4. Workshop II – Black holes and compact objects: Quantum aspects

    Indian Academy of Sciences (India)

    Parthasarathi Majumdar

    2000-10-01

    This is a summary of the papers presented in session W2 on a fairly wide-ranging variety of topics in the area of black hole physics and quantum aspects of gravity, including quantum field and string theory in curved spacetimes. In addition, experts in a couple of topical subjects were invited to present short surveys on the subjects of their specialization. The invited speakers were: Mitra, who surveys recent research on the very topical area of AdS black holes, and Date, who presents a comparative perspective on trapping and isolated horizons. Among the contributed papers, the first, by Jassal, is an attempt to understand the dynamics of strings near a black hole horizon. This is followed by a paper by Barve et al on a calculation of the quantum stress tensor for a background that includes a naked singularity. Following this we have Singh on radial oscillations of quark stars in strong magnetic fields. The next paper by Goyal and Dahiya, discusses chiral symmetry restoration in a linear sigma model in the presence of a magnetic field. The following paper, by Horwitz, offers new perspectives on the intriguing question of primordial black holes. Finally, Madhavan discusses issues pertaining to the classical limit of kinematical quantum gravity

  5. Accretion processes for general spherically symmetric compact objects

    International Nuclear Information System (INIS)

    We investigate the accretion process for different spherically symmetric space-time geometries for a static fluid. We analyze this procedure using the most general black hole metric ansatz. After that, we examine the accretion process for specific spherically symmetric metrics obtaining the velocity of the sound during the process and the critical speed of the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric for a barotropic fluid. (orig.)

  6. Accretion processes for general spherically symmetric compact objects

    Energy Technology Data Exchange (ETDEWEB)

    Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom); Jamil, Mubasher [National University of Sciences and Technology (NUST), H-12, Department of Mathematics, School of Natural Sciences (SNS), Islamabad (Pakistan)

    2015-10-15

    We investigate the accretion process for different spherically symmetric space-time geometries for a static fluid. We analyze this procedure using the most general black hole metric ansatz. After that, we examine the accretion process for specific spherically symmetric metrics obtaining the velocity of the sound during the process and the critical speed of the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric for a barotropic fluid. (orig.)

  7. 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 ope...

  8. Compact Spreader Schemes

    Energy Technology Data Exchange (ETDEWEB)

    Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.

    2014-07-25

    This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.

  9. 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.

  10. 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

  11. 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.

  12. 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 ...

  13. 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

  14. 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.

  15. The Next Generation Virgo Cluster Survey. XII. Stellar Populations and Kinematics of Compact, Low-mass Early-type Galaxies from Gemini GMOS-IFU Spectroscopy

    Science.gov (United States)

    Guérou, Adrien; Emsellem, Eric; McDermid, Richard M.; Côté, Patrick; Ferrarese, Laura; Blakeslee, John P.; Durrell, Patrick R.; MacArthur, Lauren A.; Peng, Eric W.; Cuillandre, Jean-Charles; Gwyn, Stephen

    2015-05-01

    We present Gemini Multi Object Spectrograph integral-field unit (GMOS-IFU) data of eight compact, low-mass early-type galaxies (ETGs) in the Virgo cluster. We analyze their stellar kinematics and stellar population and present two-dimensional maps of these properties covering the central 5″ × 7″ region. We find a large variety of kinematics, from nonrotating to highly rotating objects, often associated with underlying disky isophotes revealed by deep images from the Next Generation Virgo Cluster Survey. In half of our objects, we find a centrally concentrated younger and more metal-rich stellar population. We analyze the specific stellar angular momentum through the λR parameter and find six fast rotators and two slow rotators, one having a thin counterrotating disk. We compare the local galaxy density and stellar populations of our objects with those of 39 more extended low-mass Virgo ETGs from the SMAKCED survey and 260 massive (M > 1010 {{M}⊙ }) ETGs from the ATLAS3D sample. The compact low-mass ETGs in our sample are located in high-density regions, often close to a massive galaxy, and have, on average, older and more metal-rich stellar populations than less compact low-mass galaxies. We find that the stellar population parameters follow lines of constant velocity dispersion in the mass-size plane, smoothly extending the comparable trends found for massive ETGs. Our study supports a scenario where low-mass compact ETGs have experienced long-lived interactions with their environment, including ram-pressure stripping and gravitational tidal forces, that may be responsible for their compact nature.

  16. A Method of Object-based De-duplication

    Directory of Open Access Journals (Sweden)

    Fang Yan

    2011-12-01

    Full Text Available Today, the world is increasingly awash in more and more unstructured data, not only because of the Internet, but also because data that used to be collected on paper or media such as film, DVDs and compact discs has moved online [1]. Most of this data is unstructured and in diverse formats such as e-mail, documents, graphics, images, and videos. In managing unstructured data complexity and scalability, object storage has a clear advantage. Object-based data de-duplication is the current most advanced method and is the effective solution for detecting duplicate data. It can detect common embedded data for the first backup across completely unrelated files and even when physical block layout changes. However, almost all of the current researches on data de-duplication do not consider the content of different file types, and they do not have any knowledge of the backup data format. It has been proven that such method cannot achieve optimal performance for compound files.In our proposed system, we will first extract objects from files, Object_IDs are then obtained by applying hash function to the objects. The resulted Object_IDs are used to build as indexing keys in B+ tree like index structure, thus, we avoid the need for a full object index, the searching time for the duplicate objects reduces to O(log n.We introduce a new concept of a duplicate object resolver. The object resolver mediates access to all the objects and is a central point for managing all the metadata and indexes for all the objects. All objects are addressable by their IDs which is unique in the universe. The resolver stores metadata with triple format. This improved metadata management strategy allows us to set, add and resolve object properties with high flexibility, and allows the repeated use of the same metadata among duplicate object.

  17. Compact CNN for Indexing Egocentric Videos

    OpenAIRE

    Poleg, Yair; Ephrat, Ariel; Peleg, Shmuel; Arora, Chetan

    2015-01-01

    While egocentric video is becoming increasingly popular, browsing it is very difficult. In this paper we present a compact 3D Convolutional Neural Network (CNN) architecture for long-term activity recognition in egocentric videos. Recognizing long-term activities enables us to temporally segment (index) long and unstructured egocentric videos. Existing methods for this task are based on hand tuned features derived from visible objects, location of hands, as well as optical flow. Given a spars...

  18. MULTIPLE OBJECTS

    Directory of Open Access Journals (Sweden)

    A. A. Bosov

    2015-04-01

    Full Text Available Purpose. The development of complicated techniques of production and management processes, information systems, computer science, applied objects of systems theory and others requires improvement of mathematical methods, new approaches for researches of application systems. And the variety and diversity of subject systems makes necessary the development of a model that generalizes the classical sets and their development – sets of sets. Multiple objects unlike sets are constructed by multiple structures and represented by the structure and content. The aim of the work is the analysis of multiple structures, generating multiple objects, the further development of operations on these objects in application systems. Methodology. To achieve the objectives of the researches, the structure of multiple objects represents as constructive trio, consisting of media, signatures and axiomatic. Multiple object is determined by the structure and content, as well as represented by hybrid superposition, composed of sets, multi-sets, ordered sets (lists and heterogeneous sets (sequences, corteges. Findings. In this paper we study the properties and characteristics of the components of hybrid multiple objects of complex systems, proposed assessments of their complexity, shown the rules of internal and external operations on objects of implementation. We introduce the relation of arbitrary order over multiple objects, we define the description of functions and display on objects of multiple structures. Originality.In this paper we consider the development of multiple structures, generating multiple objects.Practical value. The transition from the abstract to the subject of multiple structures requires the transformation of the system and multiple objects. Transformation involves three successive stages: specification (binding to the domain, interpretation (multiple sites and particularization (goals. The proposed describe systems approach based on hybrid sets

  19. Compact synchrotron radiation source

    International Nuclear Information System (INIS)

    A compact 800 MeV synchrotron radiation source is discussed. The storage ring has a circumference of 30.3 m, two 90 degree and four 45 degree bending magnet sections, two long straight sections and four short straight sections. The radius of the bending magnet is 2.224m. The critical wave length is 24A. The injector is a 15 Mev Microtron Electrons are accelerated from 15 Mev to 800 Mev by ramping the field of the ring. The expected stored current will be around 100 ma

  20. Atacama Compact Array Antennas

    OpenAIRE

    Saito, Masao; Inatani, Junji; Nakanishi, Kouichiro; Naoi, Takahiro; Yamada, Masumi; Saito, Hiro; Ikenoue, Bungo; Kato, Yoshihiro; Morita, Kou-ichiro; Mizuno, Norikazu; Iguchi, Satoru

    2011-01-01

    We report major performance test results of the Atacama Compact Array (ACA) 7-m and 12-m antennas of ALMA (Atacama Large Millimeter/submillimeter Array). The four major performances of the ACA antennas are all-sky pointing (to be not more than 2.0 arcsec), offset pointing (to be < 0.6 arcsec) surface accuracy (< 25(20) micrometer for 12(7)m-antenna), stability of path-length (15 micrometer over 3 min), and high servo capability (6 degrees/s for Azimuth and 3 degrees/s for Elevation). The high...

  1. 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.

  2. Object theatre

    DEFF Research Database (Denmark)

    Ryöppy, Merja; Heiberg, Andreas

    2015-01-01

    This paper investigates how four perspectives from Object Theatre can enhance interaction design in the early stages of a product design process. We propose these perspectives as a playful approach for designers to gain embodied understanding and perception of objects to enable new design...... possibilities to emerge. We present a study in which the Object Theatre approach is applied to redesign socially shared everyday products that are located in public places. This project demonstrates how Object Theatre offers a broad perspective form which to explore and present product interactions. In...

  3. The scenario of two families of compact stars. Pt. 1. Equations of state, mass-radius relations and binary systems

    Energy Technology Data Exchange (ETDEWEB)

    Drago, Alessandro; Pagliara, Giuseppe [Ferrara Univ. (Italy). Dipt. di Fisica e Scienze della Terra; INFN, Ferrara (Italy); Lavagno, Andrea; Pigato, Daniele [Politecnico di Torino (Italy). Dept. of Applied Science and Technology; INFN, Torino (Italy)

    2016-02-15

    We present several arguments which favor the scenario of two coexisting families of compact stars: hadronic stars and quark stars. Besides the well-known hyperon puzzle of the physics of compact stars, a similar puzzle exists also when considering delta resonances. We show that these particles appear at densities close to twice saturation density and must be therefore included in the calculations of the hadronic equation of state. Such an early appearance is strictly related to the value of the L parameter of the symmetry energy that has been found, in recent phenomenological studies, to lie in the range 40 < L < 62 MeV. We discuss also the threshold for the formation of deltas and hyperons for hot and lepton-rich hadronic matter. Similarly to the case of hyperons, also delta resonances cause a softening of the equation of state, which makes it difficult to obtain massive hadronic stars. Quark stars, on the other hand, can reach masses up to 2.75M {sub CircleDot} as predicted by perturbative QCD calculations. We then discuss the observational constraints on the masses and the radii of compact stars. The tension between the precise measurements of high masses and the indications of the existence of very compact stellar objects (with radii of the order of 10 km) is relieved when assuming that very massive compact stars are quark stars and very compact stars are hadronic stars. Finally, we discuss recent interesting measurements of the eccentricities of the orbits of millisecond pulsars in low mass X-ray binaries. The high values of the eccentricities found in some cases could be explained by assuming that the hadronic star, initially present in the binary system, converts to a quark star due to the increase of its central density. (orig.)

  4. The scenario of two families of compact stars. Pt. 1. Equations of state, mass-radius relations and binary systems

    International Nuclear Information System (INIS)

    We present several arguments which favor the scenario of two coexisting families of compact stars: hadronic stars and quark stars. Besides the well-known hyperon puzzle of the physics of compact stars, a similar puzzle exists also when considering delta resonances. We show that these particles appear at densities close to twice saturation density and must be therefore included in the calculations of the hadronic equation of state. Such an early appearance is strictly related to the value of the L parameter of the symmetry energy that has been found, in recent phenomenological studies, to lie in the range 40 < L < 62 MeV. We discuss also the threshold for the formation of deltas and hyperons for hot and lepton-rich hadronic matter. Similarly to the case of hyperons, also delta resonances cause a softening of the equation of state, which makes it difficult to obtain massive hadronic stars. Quark stars, on the other hand, can reach masses up to 2.75M CircleDot as predicted by perturbative QCD calculations. We then discuss the observational constraints on the masses and the radii of compact stars. The tension between the precise measurements of high masses and the indications of the existence of very compact stellar objects (with radii of the order of 10 km) is relieved when assuming that very massive compact stars are quark stars and very compact stars are hadronic stars. Finally, we discuss recent interesting measurements of the eccentricities of the orbits of millisecond pulsars in low mass X-ray binaries. The high values of the eccentricities found in some cases could be explained by assuming that the hadronic star, initially present in the binary system, converts to a quark star due to the increase of its central density. (orig.)

  5. Origin of 1015–1016 G magnetic fields in the central engine of gamma ray bursts

    International Nuclear Information System (INIS)

    Various authors have suggested that the gamma-ray burst (GRB) central engine is a rapidly rotating, strongly magnetized, ( ∼ 1015–1016 G) compact object. The strong magnetic field can accelerate and collimate the relativistic flow and the rotation of the compact object can be the energy source of the GRB. The major problem in this scenario is the difficulty of finding an astrophysical mechanism for obtaining such intense fields. Whereas, in principle, a neutron star could maintain such strong fields, it is difficult to justify a scenario for their creation. If the compact object is a black hole, the problem is more difficult since, according to general relativity it has ''no hair'' (i.e., no magnetic field). Schuster, Blackett, Pauli, and others have suggested that a rotating neutral body can create a magnetic field by non-minimal gravitational-electromagnetic coupling (NMGEC). The Schuster-Blackett form of NMGEC was obtained from the Mikhail and Wanas's tetrad theory of gravitation (MW). We call the general theory NMGEC-MW. We investigate here the possible origin of the intense magnetic fields ∼ 1015–1016 G in GRBs by NMGEC-MW. Whereas these fields are difficult to explain astrophysically, we find that they are easily explained by NMGEC-MW. It not only explains the origin of the ∼ 1015–1016 G fields when the compact object is a neutron star, but also when it is a black hole

  6. An Active Black Hole in a Compact Dwarf

    Science.gov (United States)

    Kohler, Susanna

    2016-05-01

    a supermassive black hole of ~2 million solar masses, according to the authors estimates. Paudel and collaboratorsshow that this mass is consistent with the low-mass extension of the known scaling relation between central black-hole mass and brightness of the host galaxy.Central black hole mass vs. bulge K-band magnitude. SDSS J085431.18+173730.5 (red dot) falls right on the low-mass extension of the observed scaling relation. It has similar properties to M32, another compact elliptical galaxy. [Adapted from Paudel et al. 2016]To add to the mystery, SDSS J085431.18+173730.5 has no nearby neighbors: like the few other isolated compact ellipticals recently discovered, there are no massive galaxies in the immediate vicinity that could have led to its tidal stripping. So how was this puzzling ancient galaxy formed?The authors of this study support a previously proposed flyby scenario: isolated compact ellipticals may simply be tidally stripped systems that ran away from their hosts. Paudel and collaborators suggest that SDSS J085431.18+173730.5 might have long ago interacted with NGC 2672 a galaxy group located a whopping 6.5 million light-years away before being flung out to its current location.Further studies of this unique galaxys emission profile, as well as efforts to learn about its underlying stellar population and central kinematics, will hopefully help us to better understand not only the origins of this galaxy, but how all compact ellipticals form and evolve.CitationSanjaya Paudel et al 2016 ApJ 820 L19. doi:10.3847/2041-8205/820/1/L19

  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. 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...

  9. Compact stars in $f(R,T)$ gravity

    CERN Document Server

    Das, Amit; Guha, B K; Ray, Saibal

    2016-01-01

    In the present paper we generate a set of solutions describing the interior of a compact star under $f(R,T)$ theory of gravity which admits conformal motion. We consider the equation of state (EOS) $p=\\omega\\rho$ with $0<\\omega<1$ for the fluid distribution consisting normal matter, $\\omega$ being the EOS parameter. We therefore explore several aspects of the model analytically along with graphical representations to check the physical validity as well as acceptability of it within specified observational constraint in connection to a dozen of the compact star candidates. It is shown from the presented model that these objects are nothing but radiating compact stars.

  10. ULTRA-COMPACT DWARFS IN THE CORE OF THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We have discovered both a red and a blue subpopulation of ultra-compact dwarf (UCD) galaxy candidates in the Coma galaxy cluster. We analyzed deep F475W (Sloan g) and F814W (I) Hubble Space Telescope images obtained with the Advanced Camera for Surveys Wide Field Channel as part of the Coma Cluster Treasury Survey and have fitted the light profiles of ∼5000 point-like sources in the vicinity of NGC 4874, one of the two central dominant galaxies of the Coma Cluster. Although almost all of these sources are globular clusters that remain unresolved, we found that 52 objects have effective radii between ∼10 and 66 pc, in the range spanned by dwarf globular transition objects (DGTOs) and UCDs. Of these 52 compact objects, 25 are brighter than MV ∼ -11 mag, a magnitude conventionally thought to separate UCDs and globular clusters. The UCD/DGTO candidates have the same color and luminosity distribution as the most luminous globular clusters within the red and blue subpopulations of the immensely rich NGC 4874 globular cluster system. Unlike standard globular clusters, blue and red UCD/DGTO subpopulations have the same median effective radius. The spatial distribution of UCD/DGTO candidates reveals that they congregate toward NGC 4874 and are not uniformly distributed. We find a relative deficit of UCD/DGTOs compared with globular clusters in the inner 15 kpc around NGC 4874; however, at larger radii UCD/DGTO and globular clusters follow the same spatial distribution.

  11. Advances in compact torus research

    International Nuclear Information System (INIS)

    A compact torus is a low aspect ratio, axisymmetric, closed magnetic field line configuration with no vessel wall or magnetic field coils linking the hole in the plasma toroid. This concept offers reactor advantages such as simplicity, high β, and the possibility of translation. Several methods have been used to generate compact toroids, including plasma guns, high energy particle rings, and field-reversed theta pinches. This document summarizes the results of recent work on compact toroids, presented at the first IAEA Technical Committee Meeting on Compact Torus Research held in Sydney, Australia from 4 to 7 March 1985

  12. The United Nations Global Compact: The Icelandic Participants

    OpenAIRE

    Bryndís Pjetursdóttir 1976

    2011-01-01

    The objective of this dissertation is to examine the connection between the United Nations Global Compact (UN Global Compact) and Corporate Social Responsibility. Over the years the discussion of corporate social responsibilities (CSR) has grown in accordance with growing business activities in the global arena. This applies especially to the discussion of transnational companies in the developing countries. In the developing countries, there is a greater demand for responsible corporate prac...

  13. Compact acoustic refrigerator

    Science.gov (United States)

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  14. 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.

  15. Atacama Compact Array Antennas

    CERN Document Server

    Saito, Masao; Nakanishi, Kouichiro; Naoi, Takahiro; Yamada, Masumi; Saito, Hiro; Ikenoue, Bungo; Kato, Yoshihiro; Morita, Kou-ichiro; Mizuno, Norikazu; Iguchi, Satoru

    2011-01-01

    We report major performance test results of the Atacama Compact Array (ACA) 7-m and 12-m antennas of ALMA (Atacama Large Millimeter/submillimeter Array). The four major performances of the ACA antennas are all-sky pointing (to be not more than 2.0 arcsec), offset pointing (to be < 0.6 arcsec) surface accuracy (< 25(20) micrometer for 12(7)m-antenna), stability of path-length (15 micrometer over 3 min), and high servo capability (6 degrees/s for Azimuth and 3 degrees/s for Elevation). The high performance of the ACA antenna has been extensively evaluated at the Site Erection Facility area at an altitude of about 2900 meters. Test results of pointing performance, surface performance, and fast motion capability are demonstrated.

  16. Compact pentaquark structures

    CERN Document Server

    Santopinto, Elena

    2016-01-01

    We study the possibility that at least one of the two pentaquark structures recently reported by LHCb can be described as a compact pentaquark state, and we give predictions for new channels that can be studied by the experimentalists if this hypothesis is correct. We use very general arguments dictated by symmetry considerations, in order to describe the pentaquark states within a group theory approach. A complete classification of all possible states and quantum numbers, that can be useful both to the experimentalists, for new finding, or to theoretical model builders, are given, without the introduction of any particular dynamical model. Some prediction are finally given using a Guersey-Radicati inspired mass formula. We reproduce the mass and the quantum numbers of the lightest pentaquark state reported by LHCb ( 3/2^-), with a parameter free mass formula, fixed on the well established baryons. We predict others pentaquark resonances (giving their masses, and suggesting possible decay channels) which belo...

  17. 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

  18. 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.

  19. Trusted Objects

    Energy Technology Data Exchange (ETDEWEB)

    CAMPBELL,PHILIP L.; PIERSON,LYNDON G.; WITZKE,EDWARD L.

    1999-10-27

    In the world of computers a trusted object is a collection of possibly-sensitive data and programs that can be allowed to reside and execute on a computer, even on an adversary's machine. Beyond the scope of one computer we believe that network-based agents in high-consequence and highly reliable applications will depend on this approach, and that the basis for such objects is what we call ''faithful execution.''

  20. Compact Range Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Measures electrical properties and characteristics of antenna systems and performs radar cross section (RCS) measurements of objects. These data are used...

  1. 15 years of VLBI observations of two compact radio sources in Messier 82

    CERN Document Server

    Beswick, R J; Fenech, D; Marti-Vidal, I; McDonald, A R; Muxlow, T W B; Pedlar, A; Riley, J D; Wills, K A

    2006-01-01

    We present the results of a second epoch of 18cm global Very Long-Baseline Interferometry (VLBI) observations, taken on 23 February 2001, of the central kiloparsec of the nearby starburst galaxy Messier 82. These observations further investigate the structural and flux evolution of the most compact radio sources in the central region of M82. The two most compact radio objects in M82 have been investigated (41.95+575 and 43.31+592). Using this recent epoch of data in comparison with our previous global VLBI observations and two earlier epochs of European VLBI Network observations we measure expansion velocities in the range of 1500-2000km/s for 41.95+575, and 9000-11000km/s for 43.31+592 using various independent methods. In each case the measured remnant expansion velocities are significantly larger than the canonical expansion velocity (500km/s) of supernova remnants within M82 predicted from theoretical models. In this paper we discuss the implications of these measured expansion velocities with respect to ...

  2. The central region of the Fornax cluster; 2, Spectroscopy and radial velocities of member and background galaxies

    CERN Document Server

    Hilker, M; Vieria, G; Kissler-Patig, M; Richtler, T

    1998-01-01

    Radial velocities of 94 galaxies brighter than about V_tot = 20 mag in the direction of the central Fornax cluster have been measured. Except for 8 Fornax members, all galaxies lie in the background. Among the 8 members, there are 5 nucleated dwarf ellipticals that are already listed in the FCC (Ferguson 1989, AJ 98, 367). Two of the 3 ``new'' members are very compact and have surface brightnesses comparable to globular clusters, however their luminosities are in the range of dwarf elliptical nuclei. The measured line indices (especially Mg2, H beta, and iron) of the brighter of the compact objects suggest a solar metallicity, whereas the fainter compact object as well as the dE,Ns have line indices that are similar to those of old metal-poor globular clusters (GCs). However, with these data it is not possible to clearly classify the compact objects either as very bright globular clusters, isolated nuclei of dE,Ns, or even compact ellipticals. A background galaxy cluster at z = 0.11 has been found just behind...

  3. 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.)

  4. 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…

  5. 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%.

  6. Ion diffusion in compacted bentonite

    International Nuclear Information System (INIS)

    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, Kd, 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.)

  7. Fashion Objects

    DEFF Research Database (Denmark)

    Andersen, Bjørn Schiermer

    2009-01-01

    This article attempts to create a framework for understanding modern fashion phenomena on the basis of Durkheim's sociology of religion. It focuses on Durkheim's conception of the relation between the cult and the sacred object, on his notion of 'exteriorisation', and on his theory of the social...... symbol in an attempt to describe the peculiar attraction of the fashion object and its social constitution. However, Durkheim's notions of cult and ritual must undergo profound changes if they are to be used in an analysis of fashion. The article tries to expand the Durkheimian cult, radically enlarging...... of the enlargement of the cult into individual behaviour....

  8. Setting Objectives

    Science.gov (United States)

    Elkins, Aaron J.

    1977-01-01

    The author questions the extent to which educators have relied on "relevance" and learner participation in objective-setting in the past decade. He describes a useful approach to learner-oriented evaluation in which content relevance was not judged by participants until after they had been exposed to it. (MF)

  9. 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.

  10. Hydraulic Conductivity of Compacted Laterite Treated with Iron Ore Tailings

    Directory of Open Access Journals (Sweden)

    Umar Sa’eed Yusuf

    2016-01-01

    Full Text Available The objective of this study was to investigate the effect of iron ore tailings (IOT on hydraulic conductivity of compacted laterite. The IOT conforms to ASTM C 618-15 Type F designations. In the present study, soil was admixed with 0–20% IOT and compacted at moulding water content ranging from 10 to 25% using four types of compactive efforts. Hydraulic conductivities of the compacted soil-IOT mixtures were determined using deionized water and municipal solid waste leachate as the permeant fluids, respectively. Deionized water was the reference permeant fluid. Results of this study showed that hydraulic conductivity decreased with increase in IOT content as a result of improvement in mechanical properties of the soil. Permeation of the soil-IOT mixtures with leachate caused the hydraulic conductivity to drop to less than 1 × 10−9 m/s especially at higher compactive efforts. Also, bioclogging of the soil pores due to accumulation of biomass from bacteria and yeast present in the leachate tends to significantly reduce the hydraulic conductivity. From an economic point of view, it has been found from the results of this study that soil specimens treated with up to 20% IOT and compacted at the British Standard Light (BSL compactive effort met the maximum regulatory hydraulic conductivity of less than or equal to 1 × 10−9 m/s for hydraulic barrier system.

  11. Influence of Conservation Tillage and Soil Water Content on Crop Yield in Dryland Compacted Alfisol of Central Chile Influencia de la Labranza de Conservación y el Contenido de Agua sobre el Rendimiento del Cultivo en un Alfisol compactado del Secano Central de Chile

    Directory of Open Access Journals (Sweden)

    Ingrid Martinez G

    2011-12-01

    Full Text Available Chilean dryland areas of the Mediterranean climate region are characterized by highly degraded and compacted soils, which require the use of conservation tillage systems to mitigate water erosion as well as to improve soil water storage. An oat (Avena sativa L. cv. Supernova-INIA - wheat (Triticum aestivum L. cv. Pandora-INIA crop rotation was established under the following conservation systems: no tillage (Nt, Nt + contour plowing (Nt+Cp, Nt + barrier hedge (Nt+Bh, and Nt + subsoiling (Nt+Sb, compared to conventional tillage (Ct to evaluate their influence on soil water content (SWC in the profile (10 to 110 cm depth, the soil compaction and their interaction with the crop yield. Experimental plots were established in 2007 and lasted 3 yr till 2009 in a compacted Alfisol. At the end of the growing seasons, SWC was reduced by 44 to 51% in conservation tillage systems and 60% in Ct. Soil water content had a significant (p En Chile, las zonas de clima mediterráneo se caracterizan por suelos altamente degradados y compactados por erosión, lo que requiere el uso de sistemas de labranza conservacionista para mitigar la erosión hídrica, así como incrementar el contenido de agua en el suelo. Se evaluó una rotación avena (Avena sativa L. cv. Supernova-INIA - trigo (Triticum aestivum L. cv. Pandora-INIA establecida bajo los siguientes sistemas conservacionistas: cero labranza (Nt, Nt + curvas de nivel (Nt+Cp, Nt + franjas vivas (Nt+Bh y Nt + subsolado (Nt+Sb, las que fueron comparadas al sistema de labranza convencional (Ct, para evaluar su influencia en el contenido de agua en el suelo (SWC en el perfil (10 a 110 cm profundidad, la compactación del suelo y su interacción con el rendimiento del cultivo. Las parcelas experimentales fueron establecidas 3 años seguidos (2007 al 2009 en un Alfisol compactado. Al final de la temporada, el SWC disminuyó 44 a 51% en los sistemas conservacionistas y 60% en el sistema convencional. El sistema de

  12. Compact toroid formation experiments

    International Nuclear Information System (INIS)

    We present the design and experimental performance of a compact toroid (CT) formation experiment. The device has co-axial electrode diameters of 0.9 m (inner) and 1.25 m (outer), and an electrode length of ∼ 1.2 m, including an expansion/drift section. The CT is formed by a 0.1--0.2 Tesla initial radial magnetic field embedded co-axial puff gas discharge. The gas puff is injected with an array of 60 pulsed solenoid driven fast valves. The formation discharge is driven by a 108 microfarad, 40 to 100 KV, 86 to 540 kilojoule 2 to 5 megamp capacitor discharge with ∼ 20 nanohenry initial total discharge inductance. The hardware includes transmission line connections for a Shiva Star (1300 microfarad, up to 120 KV, 0.4 megajoule) capacitor bank driven acceleration discharge. Experimental measurements include current, voltage; azimuthal, radial and axial magnetic field at numerous location; fast photography, optical spectroscopy; microwave, CO2 laser, and He-Ne laser interferometry. Auxiliary experiments include Penning ionization gauge, pressure probe, and breakdown gas trigger diagnostics of gas injection, and Hall probe measurements of magnetic field injection

  13. Compactable reactor waste characterization

    International Nuclear Information System (INIS)

    Compactable reactor wastes were characterized in respect of physical composition. β/γ activity levels, radionuclide inventory, and tritium and carbon-14 content. 1072 bags of waste representing 18 bales with a volume of 9 m3 were examined. This waste is extremely heterogeneous and can contain any item or material used at nuclear generating stations. The β/γ activity level of the waste is low; at the time of manufacture the 18 bales ranged between 1.0 and 6.94 mCi most of which was attributable to radionuclides with a half-life of one year or less. After ten years' decay the activity of any bale will have decreased to a maximum of 1.5 mCi and the only β/γ radionuclides of significance will be 60Co and 137Cs. Tritium and carbon-14 were found in most of the waste bags and it is estimated that a cubic metre of waste could contain 8.4 to 11.3 Ci of tritium and 0.8 to 5.4 μCi carbon-14. It is considered there is no need for further conditioning of this waste for disposal

  14. Objective thermomechanics

    OpenAIRE

    Fülöp, Tamás

    2015-01-01

    An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but also a relaxed metric. The elastic state variable is defined through comparing these two met...

  15. Objective Morality

    OpenAIRE

    Allott, Robin

    1991-01-01

    An objective basis for morality can be found in an evolutionary account of its origin and development. Morality is a key factor in the success of human groups in competition or co-existence with each other.A group's moral code represents an increasingly rational pattern of behaviour derived from the collective experience of the group handed down from generation to generation. Group selection is a controversial idea for animal evolution but it is inescapable in accounting for human evolution u...

  16. 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)

  17. Compact Holographic Data Storage

    Science.gov (United States)

    Chao, T. H.; Reyes, G. F.; Zhou, H.

    2001-01-01

    NASA's future missions would require massive high-speed onboard data storage capability to Space Science missions. For Space Science, such as the Europa Lander mission, the onboard data storage requirements would be focused on maximizing the spacecraft's ability to survive fault conditions (i.e., no loss in stored science data when spacecraft enters the 'safe mode') and autonomously recover from them during NASA's long-life and deep space missions. This would require the development of non-volatile memory. In order to survive in the stringent environment during space exploration missions, onboard memory requirements would also include: (1) survive a high radiation environment (1 Mrad), (2) operate effectively and efficiently for a very long time (10 years), and (3) sustain at least a billion write cycles. Therefore, memory technologies requirements of NASA's Earth Science and Space Science missions are large capacity, non-volatility, high-transfer rate, high radiation resistance, high storage density, and high power efficiency. JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Compact Holographic Data Storage (CHDS) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electrooptic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and high-speed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology meeting the high radiation challenge facing the Europa Lander mission. Additional information is contained in the original extended abstract.

  18. Quantum Objects

    CERN Document Server

    Mansouri, Alireza; Karbasizadeh, Amir Ehsan

    2013-01-01

    In this paper, we suggest an alternative interpretation for the quantum state vector, which, by considering temporal parts for physical objects, aims to give an intelligible account of measurement problem in quantum mechanics. We examine the capacity of this interpretation as for explaining three measurement problems: the problem of outcome, the problem of statistics and the problem of effect. We argue that, this interpretation of the state vector, while providing a satisfactory account, as rationally plausible as its rivals, for the measurement problem, shows yet another limitation of our perceptual experience, i.e. our inability to perceive unsharp reality.

  19. Wow!: objects

    OpenAIRE

    Freitas, Paulo Sérgio da Silva

    2008-01-01

    Nowadays computers have advanced beyond the desktop into many parts of everyday life and objects. To achieve this we have to make the computer invisible, and making a computer invisible is not a matter of size of the hardware, it’s all about how the human perceives the computer. To make this possible, the interaction with the computer has to be done in an alternative way, such that the user doesn’t notice the usual computer interfaces (mouse and keyboard) when using it. Therefore this t...

  20. FIR galaxies with compact radio cores

    Science.gov (United States)

    Chini, R.; Biermann, P. L.; Kreysa, E.; Kuhr, H.; Mezger, P. G.; Schmidt, J.; Witzel, A.; Zensus, J. A.

    1987-07-01

    Comparing the IRAS point-source catalog (1985) with sources detected in a VLBI extragalactic radio source survey (Zensus et al., 1984), five FIR sources are found which all show compact radio cores. These objects have been observed with the 30-m MRT at Pico Veleta (Spain) at 1.2-mm wavelength to provide spectral coverage between IRAS and radio bands. The two galaxies among the five sources have luminosities of order 10 to the 12th solar luminosities in the FIR and thus may be super star bursters similar to Arp 220. On the other hand, all five objects have active galactic nuclei, and so the FIR luminosities may be powered by the nuclear activity. Since flat-spectrum radio sources have compact nuclear components, the 1-Jy catalog and its extension to lower flux densities (Kuehr et al., 1979 and 1981) are compared with the IRAS catalog, and a small number of additional active nuclei with strong emission in the FIR are identified. These objects can serve to study the competition between starbursts and nuclear activity to explain high FIR luminosities.

  1. Hydrochemical behaviour of compacted swelling soils

    International Nuclear Information System (INIS)

    The use of compacted soils in engineering practice is very wide spread, especially in geotechnical and environmental engineering. These soils can be submitted to moisture variations, i.e. suction changes, that induce volumetric deformations. The main objective of this thesis is to study the suction influence on the hydro-mechanical behaviour of a compacted swelling soil in the range of suction comprised between 0 and 300 MPa. For this purpose, two kinds of suction controlled odometers, using the osmotic method or the salt solutions technique. were employed. The salt solutions odometer were especially developed for this study. The samples were made with a compacted swelling material. The experimental study has shown that the apparent pre-consolidation stress reaches a constant value above a suction of 38.9 MPa. The slope of the plastic compression curve had a maximum value under a suction of 4 MPa. These results seem to be related to the initial internal structure of the samples. Then the influence of complex hydro-mechanical stress paths was also investigated. It appeared that the results of the tests conducted on a swelling soil depended on the followed stress path even if a wetting is performed during a test. In the last part of this work, the test results were interpreted with the Barcelona Basic Model and Barcelona Expansive Model (BExM). The possibilities of both models were compared. To interpret the test results with the BExM, it is necessary to conduct some additional tests that include a suction cycle and also a constant volume test with a suction controlled wetting. As a conclusion, two suction controlled experimental devices were developed and validated in this study. With these devices, the influence of structure and suction on the hydro-mechanical behaviour of a compacted swelling soils was characterised. (author)

  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. 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...

  4. Mesoscale Simulations of Powder Compaction

    Science.gov (United States)

    Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-01

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  5. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    International Nuclear Information System (INIS)

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  6. A compact rotary vane attenuator

    Science.gov (United States)

    Nixon, D. L.; Otosh, T. Y.; Stelzried, C. T.

    1969-01-01

    Rotary vane attenuator, when used as a front end attenuator, introduces an insertion loss that is proportional to the angle of rotation. New technique allows the construction of a shortened compact unit suitable for most installations.

  7. 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)

  8. 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...

  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. Objective thermomechanics

    CERN Document Server

    Fülöp, Tamás

    2015-01-01

    An irreversible thermodynamical theory of solids is presented where the kinematic quantities are defined in an automatically objective way. Namely, auxiliary elements like reference frame, reference time and reference configuration are avoided by formulating the motion of the continuum on spacetime directly, utilizing the Weyl-Matolcsi description of spacetime. This restricts the range of definable kinematic quantities heavily. Solids are distinguished from fluids by possessing not only an instantaneous metric tensor but a relaxed metric, too, that represents the natural geometric structure of the solid. The comparison of the instantaneous metric to the relaxed one is the basis of the definition of the elastic state variable, the elastic deformedness tensor. Thermal expansion is conceived as the temperature dependence of the relaxed metric. As opposed to this reversible type of change, plasticity means an irreversible change in the relaxed metric, and is describable via a plastic change rate tensor. The relat...

  11. Fracture of explosively compacted aluminum particles in a cylinder

    Science.gov (United States)

    Frost, David; Loiseau, Jason; Goroshin, Sam; Zhang, Fan; Milne, Alec; Longbottom, Aaron

    2015-06-01

    The explosive compaction, fracture and dispersal of aluminum particles contained within a cylinder have been investigated experimentally and computationally. The aluminum particles were weakly confined in a cardboard tube and surrounded a central cylindrical burster charge. The compaction and fracture of the particles are visualized with flash radiography and the subsequent fragment dispersal with high-speed photography. The aluminum fragments produced are much larger than the original aluminum particles and similar in shape to those generated from the explosive fracture of a solid aluminum cylinder, suggesting that the shock transmitted into the aluminum compacts the powder to near solid density. The casing of the burster explosive (plastic-, copper-, and un-cased charges were used) had little influence on the fragment size. The effect of an air gap between the burster and the aluminum particles was also investigated. The particle motion inferred from the radiographs is compared with the predictions of a multimaterial hydrocode.

  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. The INTEGRAL long monitoring of persistent Ultra Compact X-ray Bursters

    OpenAIRE

    Fiocchi, M.; Bazzano, A.; Ubertini, P.; Bird, A. J.; Natalucci, L; Sguera, V.

    2008-01-01

    The combination of compact objects, short period variability and peculiar chemical composition of the Ultra Compact X-ray Binaries make up a very interesting laboratory to study accretion processes and thermonuclear burning on the neutron star surface. The improved large optical telescopes and more sensitive X-ray satellites have increased the number of known Ultra Compact X-ray Binaries allowing their study with unprecedented detail. We analyze the average properties common to all ultra comp...

  14. The number density of quiescent compact galaxies at intermediate redshift

    Energy Technology Data Exchange (ETDEWEB)

    Damjanov, Ivana [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hwang, Ho Seong; Geller, Margaret J.; Chilingarian, Igor, E-mail: idamjanov@cfa.harvard.edu [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)

    2014-09-20

    Massive compact systems at 0.2 < z < 0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ∼200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z ∼ 0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2 < z < 0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0 < z < 2.

  15. 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...

  16. 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.

  17. 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.

  18. Control system for a compact synchrotron

    International Nuclear Information System (INIS)

    The control system for a compact superconducting synchrotron (HELIOS) is described. The machine is intended to be used as a prototype production tool for X-ray lithography, so emphasis has been placed on engineering the control system for this purpose. The system has been designed to be flexible for commissioning, but easy to use for an operator at a lithography facility. With this in mind the following facilities have been included: keys to limit control functions, a HELP facility for operators, colour touch-panels and displays, limits and other software protection. The conservative hardware design is based on well established CAMAC interfaces. Similarly, the software runs on a MicroVAX with VMS, is written in FORTRAN 77, and is adapted from a well developed SLAC control system. Design features include the use of local intelligence for some subsystems, modular hardware and software, interlocks and a central database. (orig.)

  19. HI absorption towards nearby compact radio sources

    CERN Document Server

    Chandola, Yogesh; Saikia, D J

    2011-01-01

    We present the results of HI absorption measurements towards a sample of nearby Compact Steep-Spectrum (CSS) and Giga-Hertz Peaked Spectrum (GPS) radio sources, the CORALZ sample, using the Giant Metrewave Radio Telescope (GMRT). We observed a sample of 18 sources and find 7 new detections. These sources are of lower luminosity than earlier studies of CSS and GPS objects and we investigate any dependence of HI absorption features on radio luminosity. Within the uncertainties, the detection rates and column densities are similar to the more luminous objects, with the GPS objects exhibiting a higher detection rate than for the CSS objects. The relative velocity of the blueshifted absorption features, which may be due to jet-cloud interactions, are within $\\sim$$-$250 km s$^{-1}$ and do not appear to extend to values over 1000 km s$^{-1}$ seen for the more luminous objects. This could be due to the weaker jets in these objects, but requires confirmation from observations of a larger sample of sources. There appe...

  20. Symmetry, Compact Closure and Dagger Compactness for Categories of Convex Operational Models

    CERN Document Server

    Barnum, Howard; Wilce, Alexander

    2010-01-01

    In the categorical approach to the foundations of quantum theory, one begins with a symmetric monoidal category, the objects of which represent physical systems, and the morphisms of which represent physical processes. Usually, this category is taken to be at least compact closed, and more often, dagger compact, enforcing a certain self-duality, whereby preparation processes (roughly, states) are inter-convertible with processes of registration (roughly, measurement outcomes). This is in contrast to the more concrete "operational" approach, in which the states and measurement outcomes associated with a physical system are represented in terms of what we here call a "convex operational model": a certain dual pair of ordered linear spaces -- generally, {\\em not} isomorphic to one another. On the other hand, state spaces for which there is such an isomorphism, which we term {\\em weakly self-dual}, play an important role in reconstructions of various quantum-information theoretic protocols, including teleportatio...

  1. 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....

  2. Dynamic powder compaction of rapidly solidified Path A alloy with increased carbon and titanium content

    International Nuclear Information System (INIS)

    The objective of this study is to show the potential of the dynamic powder compaction technique to consolidate rapidly solidified Path A alloys and to develop microstructures with improved irradiation performance in the fusion environment. Samples of rapidly solidified and dynamically compacted Path A alloy with increased carbon and titanium content have been included in alloy development irradiation experiments

  3. New Strategies for Powder Compaction in Powder-based Rapid Prototyping Techniques

    NARCIS (Netherlands)

    Budding, A.; Vaneker, T.H.J.

    2013-01-01

    In powder-based rapid prototyping techniques, powder compaction is used to create thin layers of fine powder that are locally bonded. By stacking these layers of locally bonded material, an object is made. The compaction of thin layers of powder mater ials is of interest for a wide range of applicat

  4. Gravitational waves from compact bodies

    CERN Document Server

    Thorne, K S

    1995-01-01

    A review is given of recent research on gravitational waves from compact bodies and its relevance to the LIGO/VIRGO international network of high-frequency (10 to 10,000 Hz) gravitational-wave detectors, and to the proposed LISA system of low-frequency (0.1 to 0.0001 Hz) detectors. The sources that are reviewed are ordinary binary star systems, binaries made from compact bodies (black holes and neutron stars), the final inspiral and coalescence of compact-body binaries, the inspiral of stars and small black holes into massive black holes, the stellar core collapse that triggers supernovae, and the spin of neutron stars. This paper is adapted from a longer review article entitled ``Gravitational Waves'' (GRP-411) that the author has written for the Proceedings of the Snowmass '94 Summer Study on Particle and Nuclear Astrophysics and Cosmology.

  5. Compact E+A Galaxies as a Progenitor of Massive Compact Quiescent Galaxies at 0.2

    CERN Document Server

    Zahid, H Jabran; Geller, Margaret J; Damjanov, Ivana; Chillingarian, Igor; Sohn, Jubee; Salmi, Fadia; Hwang, Ho Seong

    2016-01-01

    We search the Sloan Digital Sky Survey and the Baryon Oscillation Sky Survey to identify ~5500 massive compact quiescent galaxy candidates at 0.2compact E+A galaxies suggest that they are a progenitor of massive compact quiescent galaxies. Thus, two separate classes of objects-compact E+A and compact quiescent galaxies-may be linked by a common evolutionary sequence. The typical stellar population age of compact E+A galaxies is <1 Gyr. The existence of compact E+A galaxies with young stellar populations at 0.2compact quiescent galaxies first appear at intermediate redshifts. We derive a lower limit for the number density of compact E+A galaxies. Assuming passive evolution, we convert this number density into an app...

  6. Effects of Comptonization By Outflowing Plasma in Compact X-ray Sources

    Science.gov (United States)

    Shrader, C. R.; Titarchuk, L. G.

    2003-12-01

    We describe our study of the effects outflowing plasma on the high-energy continuum spectra of accretion powered compact objects. The basic idea is that Thomson scattering of the photons from the central source entering the expanding flow experience a decrease of their energy which is of first order in v/c, where v is the outflow velocity and c is the speed of light. We predict that the emergent spectrum should be closely related to the distribution of photons diffusing through the wind. To test this hypothesis, we have developed an analytical formulation for the emergent spectrum of a compact accretion driven system in a circumstellar wind environment, and performed model fitting on several Galactic X-ray binaries. Notably, Cygnus X-3 is which is widely believed to be characterized by hot, dense circumstellar winds provides the prototypical test case. Observational data from INTEGRAL and RXTE are included in our analysis. In addition to Cyg X-3, we have applied our model to several other well known X-ray binaries, for which the presence of wind outflow is not firmly established, but may nonetheless be present. We further consider the possibility that the well documented distortion of the pure power-law continuum above 10 keV, the so called "reflection bump", may in some cases be explained by the spectral softening effects of the outflow.

  7. Compactly supported multi-wavelets

    Directory of Open Access Journals (Sweden)

    Wojciech Banaś

    2012-01-01

    Full Text Available In this paper we show some construction of compactly supported multi-wavelets in \\(L^2(\\mathbb{R}^d\\, \\(d \\geq 2\\ which is based on the one-dimensional case, when \\(d=1\\. We also demonstrate that some methods, which are useful in the construction of wavelets with a compact support at \\(d=1\\, can be adapted to higher-dimensional cases if \\(A \\in M_{d \\times d}(\\mathbb{Z}\\ is an expansive matrix of a special form.

  8. 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

  9. Modeling of compact loop antennas

    Science.gov (United States)

    Baity, F. W.

    1987-09-01

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively tuned resonant double loop (RDL) antennas, the model treats sub-tuned RDL antennas. Calculations using the model have been compared with measurements on full-scale mock-ups of RDL antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and the Compact Ignition Tokamak (CIT).

  10. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

  11. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively tuned resonant double loop (RDL) antennas, the model treats sub-tuned RDL antennas. Calculations using the model have been compared with measurements on full-scale mock-ups of RDL antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and the Compact Ignition Tokamak

  12. Formation and evolution of blue compact dwarfs: The origin of their steep rotation curves

    CERN Document Server

    Watts, A

    2016-01-01

    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 6 times higher than those of the initial dwarf irregulars. However, the more compact dark matter halo alone can not 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 r...

  13. The Next Generation Virgo Cluster Survey. XII. Stellar Populations and Kinematics of Compact, Low-Mass Early-Type Galaxies from Gemini GMOS-IFU Spectroscopy

    CERN Document Server

    Guerou, Adrien; McDermid, Richard M; Cote, Patrick; Ferrarese, Laura; Blakeslee, John P; Durrell, Patrick R; MacArthur, Lauren A; Peng, Eric W; Cuillandre, Jean-Charles; Gwyn, Stephen

    2015-01-01

    We present Gemini GMOS-IFU data of eight compact low-mass early-type galaxies (ETGs) in the Virgo cluster. We analyse their stellar kinematics, stellar population, and present two-dimensional maps of these properties covering the central 5"x 7" region. We find a large variety of kinematics: from non- to highly-rotating objects, often associated with underlying disky isophotes revealed by deep images from the Next Generation Virgo Cluster Survey. In half of our objects, we find a centrally-concentrated younger and more metal-rich stellar population. We analyze the specific stellar angular momentum through the lambdaR parameter and find six fast-rotators and two slow-rotators, one having a thin counter-rotating disk. We compare the local galaxy density and stellar populations of our objects with those of 39 more extended low-mass Virgo ETGs from the SMAKCED survey and 260 massive ($M>10^{10}$\\Msun) ETGs from the A3D sample. The compact low-mass ETGs in our sample are located in high density regions, often close...

  14. CYANATE ION IN COMPACT AMORPHOUS WATER ICE

    Energy Technology Data Exchange (ETDEWEB)

    Mate, Belen; Herrero, Victor J.; Rodriguez-Lazcano, Yamilet; Moreno, Miguel A.; Escribano, Rafael [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, E-28006 Madrid (Spain); Fernandez-Torre, Delia [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, E-28050 Madrid (Spain); Gomez, Pedro C. [Departamento de Quimica Fisica I, Universidad Complutense, Unidad Asociada UCM-CSIC, E-28040 Madrid (Spain)

    2012-11-10

    The 4.62 {mu}m infrared (2164.5 cm{sup -1}) absorption band, observed in ice mantels toward many young stellar objects, has been mostly attributed to the {nu}{sub 3} (CN stretch) band of OCN{sup -} ions. We present in this work a spectroscopic study of OCN{sup -} ions embedded in compact amorphous ice in a range of concentrations and temperatures relevant to astronomical observations together with quantum mechanical calculations of the {nu}{sub 3} band of OCN{sup -} in various H{sub 2}O environments. The ice samples containing the ions are prepared through hyperquenching of liquid droplets of K{sup +}OCN{sup -} solutions on a substrate at 14 K. The {nu}{sub 3} OCN{sup -} band appears as a broad feature peaking at 4.64 {mu}m with a secondary maximum at 4.54 {mu}m and is much weaker than the corresponding peak in the liquid solution or in the solid salt. A similar weakening is observed for other OCN{sup -} absorption peaks at 7.66 {mu}m (2{nu}{sub 2}) and 8.20 {mu}m ({nu}{sub 1}). The theoretical calculations for the {nu}{sub 3} vibration lead to a range of frequencies spanning the experimentally observed width. This frequency spread could help explain the pronounced drop in the band intensity in the ice. The OCN{sup -} {nu}{sub 3} band in the present compact ices is also broader and much weaker than that reported in the literature for OCN{sup -} ions obtained by variously processing porous ice samples containing suitable neutral precursors. The results of this study indicate that the astronomical detection of OCN{sup -} in ice mantels could be significantly impaired if the ion is embedded in a compact water network.

  15. Mesoscale Simulations of Power Compaction

    Energy Technology Data Exchange (ETDEWEB)

    Lomov, I; Fujino, D; Antoun, T; Liu, B

    2009-08-06

    Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

  16. 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.

  17. Properties of dynamically compacted WIPP salt

    International Nuclear Information System (INIS)

    Dynamic compaction of mine-run salt is being investigated for the Waste Isolation Pilot Plant (WIPP), where compacted salt is being considered for repository sealing applications. One large-scale and two intermediate-scale dynamic compaction demonstrations were conducted. Initial fractional densities of the compacted salt range form 0.85 to 0.90, and permeabilities vary. Dynamically-compacted specimens were further consolidated in the laboratory by application of hydrostatic pressure. Permeability as a function of density was determined, and consolidation microprocesses were studied. Experimental results, in conjunction with modeling results, indicate that the compacted salt will function as a viable seal material

  18. 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...

  19. Isolated compact elliptical galaxies: Stellar systems that ran away

    CERN Document Server

    Chilingarian, Igor

    2015-01-01

    Compact elliptical galaxies form a rare class of stellar system (~30 presently known) characterized by high stellar densities and small sizes and often harboring metal-rich stars. They were thought to form through tidal stripping of massive progenitors, until two isolated objects were discovered where massive galaxies performing the stripping could not be identified. By mining astronomical survey data, we have now found 195 compact elliptical galaxies in all types of environment. They all share similar dynamical and stellar population properties. Dynamical analysis for nonisolated galaxies demonstrates the feasibility of their ejection from host clusters and groups by three-body encounters, which is in agreement with numerical simulations. Hence, isolated compact elliptical and isolated quiescent dwarf galaxies are tidally stripped systems that ran away from their hosts.

  20. Some observational aspects of compact galactic X-ray sources

    International Nuclear Information System (INIS)

    This thesis contains the following observations of compact galactic X-ray sources: i) the X-ray experiments onboard the Astronomical Netherlands Satellite ANS, ii) a rocket-borne ultra soft X-ray experiment and iii) the Objective Grating Spectrometer onboard the EINSTEIN observatory. In Chapter I the various types of compact galactic X-ray sources are reviewed and put into the perspective of earlier and following observations. In Chapter II the author presents some of the observations of high luminosity X-ray sources, made with ANS, including the detection of soft X-rays from the compact X-ray binary Hercules X-1 and the ''return to the high state'' of the black hole candidate Cygnus X-1. Chapter III deals with transient X-ray phenomena. Results on low luminosity galactic X-ray sources are collected in Chapter IV. (Auth.)

  1. SOCRATES Invades Central Europe

    OpenAIRE

    Joseph Slowinski

    1998-01-01

    The objective of this article is to explore the current reality faced by higher education students in Central and Eastern Europe and to draw out the implications of this current reality for policy makers in the future. In the article, I explore the influence of transnational corporations' training programs on education as it currently pertains to Central and Eastern European higher education and employment. In addition, multinational corporate entities exercise influence on European Union pol...

  2. Compact ignition tokamak physics and engineering basis

    International Nuclear Information System (INIS)

    The Compact Ignition Tokamak (CIT) is a high-field, compact tokamak design whose objective is the study of physics issues associated with burning plasmas. The toroidal and poloidal field coils employ a copper-steel laminate, manufactured by explosive-bonding techniques, to support the forces generated by the design fields: 10 T toroidal field at the plasma center; 21 T in the OH solenoid. A combination of internal and external PF coils provides control of the equilibrium and the ability to sweep the magnetic separatrix across the divertor plates during a pulse. At temperatures and βα levels characteristic of ITER designs, the fusion power in CIT approaches 800 MW and can be the limiting factor in the pulse length. Ignition requires that the confinement time exceed present L-mode scalings by about a factor of two, which is anticipated to occur as a result of the operational flexibility incorporated into the design. Conventional operating limits given by 20 e and qψ ≤ 3.2 have been chosen and, in the case of MHD limits, have been justified by ideal stability analysis. The power required for CIT ignition ranges from 10 MW to 40 MW or more, depending on confinement assumptions, and either ICRF or ECRF heating, or both, will be used. (author). 17 refs, 6 figs, 1 tab

  3. Compaction of asphalt road pavements : using finite elements and critical state theory

    OpenAIRE

    Huerne, ter, H.L.

    2004-01-01

    The objective of this research was to investigate whether it is possible to develop a tool that enables simulation of a compaction process of asphalt for construction of roads, and how this is best done.

  4. Compact High-Resolution Broad-Band Terahertz Fabry-Perot Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Our objective is to develop a compact scanning Fabry-Perot spectrometer, for satellite far-infrared astronomy and Earth remote sensing, that operates at wavelengths...

  5. Ultra-compact, High Resolution, LADAR system for 3D Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SiWave proposes to develop an innovative, ultra-compact, high resolution, long range LADAR system to produce a 3D map of the exterior of any object in space such as...

  6. Multiple objects tracking in fluorescence microscopy

    OpenAIRE

    Kalaidzidis, Yannis

    2008-01-01

    Many processes in cell biology are connected to the movement of compact entities: intracellular vesicles and even single molecules. The tracking of individual objects is important for understanding cellular dynamics. Here we describe the tracking algorithms which have been developed in the non-biological fields and successfully applied to object detection and tracking in biological applications. The characteristics features of the different algorithms are compared. Electronic supplementary ma...

  7. The Nature of the Activity in Hickson Compact Groups of Galaxies

    CERN Document Server

    Coziol, R; De Carvalho, R R; Capelato, H V; Coziol, Roger; Ribeiro, André L. B.; Carvalho, Reinaldo R. de; Capelato, Hugo V.

    1997-01-01

    We present the results of the spectral classification of the 82 brightest galaxies in a sample of 17 compact groups. We verify that the AGNs are preferentially located in the most early-type and luminous galaxies of the groups, as is usually observed in the field. But these AGNs also appear to be systematically concentrated towards the central parts of the groups. Our observations suggest a correlation between activity types, morphologies and densities of galaxies in the compact groups. This is consistent with a scenario in which galaxies of compact groups evolve by interacting with their environment and are currently in a quiet phase of their activity

  8. Sequential normal compactness versur topological normal compactness in variational analysis

    Czech Academy of Sciences Publication Activity Database

    Fabian, Marián; Mordukhovich, B. S.

    2003-01-01

    Roč. 54, č. 6 (2003), s. 1057-1067. ISSN 0362-546X R&D Projects: GA ČR GA201/01/1198 Institutional research plan: CEZ:AV0Z1019905; CEZ:AV0Z1019905 Keywords : variational analysis * sequential and topological normal compactness * Banach spaces Subject RIV: BA - General Mathematics Impact factor: 0.354, year: 2003

  9. Tank farms compacted low-level waste

    International Nuclear Information System (INIS)

    This report describes the process of Low-Level Waste (LLW) volume reduction by compaction. Also included is the data used for characterization of LLW destined for compaction. Scaling factors (ratios) are formed based on data contained in this report

  10. 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.

  11. 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.

  12. UV written compact broadband optical couplers

    DEFF Research Database (Denmark)

    Olivero, Massimo; Svalgaard, Mikael

    In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques.......In this paper the first demonstration of compact asymmetric directional couplers made by UV writing is presented. The combined performance in terms bandwidth, loss and compactness exceeds that reported using other, more elaborate fabrication techniques....

  13. 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......-to-dust ratios of these galaxies to determine if an incorrect LCO-M(H2) conversion caused the apparent suppression and find that HCGs have normal gas-to-dust ratios. It is likely that the cause of the apparent suppression in these objects is associated with shocks injecting turbulence into the molecular gas...

  14. Neutrino trapping in braneworld extremely compact stars

    CERN Document Server

    Stuchlik, Zdenek; Urbanec, Martin

    2011-01-01

    Extremely Compact Stars (ECS) contain trapped null geodesics. When such objects enter the evolution period admitting geodetical motion of neutrinos, certain part of neutrinos produced in their interior will be trapped influencing their neutrino luminosity and thermal evolution. We study neutrino trapping in the braneworld ECS, assuming uniform distribution of neutrino emissivity and massless neutrinos. We give the efficiency of the neutrino trapping effects in the framework of the simple model of the internal spacetime with uniform distribution of energy density, and external spacetime described by the Reissner-Nordstr\\"om geometry characterized by the braneworld "tidal" parameter $b$. For $b 0$ the external spacetime can be of both black-hole and naked-singularity type. Then the ECS surface radius $R$ can be located also above the unstable (outer) photon circular orbit. Such basically new types of the spacetimes strongly alter the trapping phenomena as compared to the standard case of $b = 0$. It is shown t...

  15. Optical Spectrum of the Compact Planetary Nebula IC 5117

    Science.gov (United States)

    Hyung, Siek; Aller, Lawrence H.; Feibelman, Walter A.; Lee, Seong-Jae; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    High resolution spectroscopic data of the very compact planetary nebula IC 5117 are obtained in the optical wavelengths, 3700A - 10050A, with the Hamilton Echelle Spectrograph at Lick Observatory, and which have been analyzed along with the International Ultraviolet Explorer (IUE) UV archive data. Although a diagnostic diagram shows significant density and temperature fluctuations, our analysis indicates that the nebular gas may be represented by a homogeneous shell of extremely high density gas, N(sub epsilon) approx. 90 000 /cu cm. The average electron temperatures, e.g. indicated by the [OIII] diagnostics, are around 12 000 K. We construct a photoionization model to represent most of the observed line intensities, and the physical condition of this compact nebulosity. Based on the semi-empirical ionization correction approach, and model indications, we derived the elemental abundances: He, C, N, O, Ne, and Ar appear to be normal or marginally depleted compared to the average planetary nebula, while the remaining elements, S, Cl, and K appear to be enhanced. IC 5117 is perhaps a very young compact planetary nebula, slightly more evolved than the other well-known compact planetary nebula IC 4997. The central stellar temperature is likely to be around 120 000 K, evolved from a C-rich AGB progenitor.

  16. pH buffering in compacted bentonite

    International Nuclear Information System (INIS)

    In almost all high-level waste and spent fuel repository concepts, highly compacted bentonite in one form or another is the preferred material for backfilling and sealing. During re-saturation the bentonite swells and seals against the emplacement tunnels. The very low transmissivity to water movement and good sorption characteristics make compacted bentonite an extremely effective near-field diffusion barrier to the movement of radionuclides. The ability to give a chemically well founded pore water composition is essential since such knowledge is a pre-requisite for understanding sorption and diffusion processes, assessing the influence of long term groundwater-bentonite interactions and also predicting near-field solubilities and developing sorption data bases. In this context the pH of the pore water is of central importance, particularly for sorption. Almost invariably the compositions given for highly compacted bentonite pore waters are calculated values because reliable water samples are virtually impossible to obtain, even by squeezing under very high pressures. Assumptions and simplifications are made in the geochemical models used to perform such calculations and the predictions are seldom if ever tested. One of the main hypotheses in a recently proposed model for bentonite pore water was that the initial pH is determined by the state of the amphoteric surface hydroxy groups, ≡SOH type sites, and these buffer the pH of the pore water in to a value close to 8. Surface site types, site capacities and proto-lysis constants were obtained from previous montmorillonite titration measurements and were fixed in the calculations. The aim of this work was to test the Bradbury and Baeyens (2003) model in terms of its ability to the predict one of the most important parameters for any pore water, namely the pH. Tests against the real system are not practicable for the reasons mentioned above. Hence the experiments had to be indirect but nevertheless devised to

  17. 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

  18. Technology of compact fusion-reactor concepts

    International Nuclear Information System (INIS)

    An identification of future engineering needs of compact, high-power-density approaches to fusion power is presented. After describing a rationale for the compact approach and a number of compact fusion reactors, key technology needs are assessed relative to the similar needs of the conventional tokamak in order to emphasize differences in required technology with respect to the well-documented mainline approaches

  19. 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.

  20. Compact torus studies: Final report

    International Nuclear Information System (INIS)

    The compact torus (CT) device has been proposed for use in some applications which are of interest in Laboratory programs in the areas of pulsed power and inertial confinement fusion. These applications involve compression and acceleration of CT plasmas. The RACE (Ring Accelerator Experiment) experimental program at Livermore has been initiated to study these applications. The work reported here involves studies of plasma physics and other aspects of these compact torus applications. The studies conducted identify specific problem areas associated with the CT device and examine these areas in some detail. This report contains studies of three particular problem areas of the CT applications. These three areas are: the general nonlinear properties of the CT as a magnetohydrodynamic (MHD) equilibrium, particle simulation of the compression of the CT, with a focus on the non-MHD effects, and nonlinear RF interaction problems in the CT

  1. 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)

  2. Compaction of DNA on nanoscale three-dimensional templates.

    Science.gov (United States)

    Zinchenko, Anatoly A; Chen, Ning

    2006-07-19

    There exist several important in vivo examples, where a DNA chain is compacted on interacting with nanoscale objects such as proteins, thereby forming complexes with a well defined molecular architecture. One of the well known manifestations of such a natural organization of a semi-flexible DNA chain on nanoscale objects is hierarchical DNA molecule assembly into a chromosome, which is mediated by cationic histone proteins at the first stages of compaction. The biological importance of this and other natural nanostructural organizations of the DNA molecule has inspired many theoretical and numerical studies to gain physical insight into this problem. On the other hand, the experimental model systems containing DNA and nanoobjects, which are important to extend our knowledge beyond natural systems, were almost unavailable until the last decade. Accelerating progress in nanoscale chemistry and materials science has brought about various nanoscale three-dimensional structures such as dendrimers, nanoparticles, and nanotubes, and thus has provided a basis for the next important step in creating novel DNA-containing nanostructures, modelling of natural DNA compaction, and verification of accumulated theoretical predictions on the interaction between DNA and nanoscale templates. This review is written to highlight this early stage of nano-inspired progress and it is focused on physico-chemical and biophysical experimental investigations as well as theoretical and numerical studies dedicated to the compaction of DNA on nanoscale three-dimensional templates. PMID:21690831

  3. 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 ...

  4. Compact Color Schlieren Optical System

    Science.gov (United States)

    Buchele, Donald R.; Griffin, Devon W.

    1996-01-01

    Compact, rugged optical system developed for use in rainbow schlieren deflectometry. Features unobscured telescope with focal-length/aperture-width ratio of 30. Made of carefully selected but relatively inexpensive parts. All of lenses stock items. By-product of design is optical system with loose tolerances on interlens spacing. One of resulting advantages, insensitivity to errors in fabrication of optomechanical mounts. Another advantage is ability to compensate for some of unit-to-unit variations inherent in stock lenses.

  5. Learning Compact Recurrent Neural Networks

    OpenAIRE

    Lu, Zhiyun; Sindhwani, Vikas; Sainath, Tara N.

    2016-01-01

    Recurrent neural networks (RNNs), including long short-term memory (LSTM) RNNs, have produced state-of-the-art results on a variety of speech recognition tasks. However, these models are often too large in size for deployment on mobile devices with memory and latency constraints. In this work, we study mechanisms for learning compact RNNs and LSTMs via low-rank factorizations and parameter sharing schemes. Our goal is to investigate redundancies in recurrent architectures where compression ca...

  6. 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.

  7. 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 ...

  8. 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.

  9. Compact accelerator for clinical use

    International Nuclear Information System (INIS)

    The first clinical trial with carbon beams generated from the HIMAC was conducted in June 1994. The total number of patients treated as of October 2006 is in excess of 3,000. In view of the significant growth in the number of protocols, the Japanese government gave its approval for carbon-ion therapy at NIRS as an advanced medical technology in 2003. The impressive advances of carbon-ion therapy using HIMAC have been supported by high-reliability operation and by advanced developments of beam-delivery and accelerator technologies. Based on our ten years of experience with HIMAC, we recently proposed a compact carbon-ion therapy facility for widespread use in Japan. The key technologies of the accelerator and irradiation systems for this compact facility have been under development since April 2004, with the main thrust being focused on downsizing the facility for cost reduction. On the basis of the design and R and D studies for the compact carbon-ion facility, its construction was begun at Gunma University in April 2006. In addition, our future plans for HIMAC also include the design of a new treatment facility. The design work has already been initiated and will lead to the further development of therapy using HIMAC. The following descriptions give a summary account of the carbon-ion treatment facility and of the HIMAC facility. (author)

  10. 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.

  11. Label transfer by measuring compactness.

    Science.gov (United States)

    Varga, Robert; Nedevschi, Sergiu

    2013-12-01

    This paper presents a new automatic image annotation algorithm. First, we introduce a new similarity measure between images: compactness. This uses low level visual descriptors for determining the similarity between two images. Compactness shows how close test image features lie to training image feature cluster centers. The measure provides the core for a k-nearest neighbor type image annotation method. Afterward, a formalism for defining different transfer techniques is devised and several label transfer techniques are provided. The method as whole is evaluated on four image annotation benchmarks. The results on these sets validate the accuracy of the approach, which outperforms many state-of-the-art annotation methods. The method presented here requires a simple training process, efficiently combines different feature types and performs better than complex learning algorithms, even in this incipient form. The main contributions of this paper are the usage of compactness as a similarity measure that enables efficient low level feature comparison and an annotation algorithm based on label transfer. PMID:23955754

  12. 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.

  13. 76 FR 66326 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2011-10-26

    ... 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,...

  14. 78 FR 61384 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2013-10-03

    ... Federal Bureau of Investigation Meeting of the Compact Council for the National Crime Prevention and... of 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,...

  15. 78 FR 20355 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2013-04-04

    ... 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,...

  16. 75 FR 62568 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2010-10-12

    ... 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,...

  17. 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,...

  18. 75 FR 17161 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2010-04-05

    ... Federal Bureau of Investigation Meeting of the Compact Council for the National Crime Prevention and... purpose of 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)....

  19. 77 FR 60475 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2012-10-03

    ... Federal Bureau of Investigation Meeting of the Compact Council for the National Crime Prevention and... of 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,...

  20. 77 FR 20051 - Meeting of the Compact Council for the National Crime Prevention and Privacy Compact

    Science.gov (United States)

    2012-04-03

    ... 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,...

  1. Placement of pre-compacted and in situ compacted dense backfill materials in shaft seals

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In 2003, a decision was made to discontinue operation of Atomic Energy of Canada Limited's (AECL's) Underground Research Laboratory (URL) and ultimately to decommission and permanently close the underground portion of this facility. As part of the Nuclear Legacy Liability Program (NLLP) being funded by Natural Resources Canada (NRCan), an ongoing program of work is being undertaken to decommission and deal with facilities that are no longer part of AECL's mandate or operations. The URL is included in these facilities. Part of this work is the installation of seals at the intersection of the access and ventilation shafts and an ancient thrust fault, Fracture Zone 2 (FZ2), approximately 275 m below surface. These seals are being installed in order to limit the potential for mixing of deeper saline and shallower, less saline groundwater. The seal design in each shaft is similar with a heavily reinforced lower concrete component, a central bentonite clay-sand component and an upper un-reinforced concrete component. The main shaft at the URL at the location of the seal is circular (∼5-m diameter), and was excavated using careful drill and blast techniques. The seal itself consists of two keyed, conical sectioned, 3-m-thick by 5 to 6-m diameter concrete segments that confine a 6-m-thick swelling clay section. The ventilation shaft at the URL is 1.8 m in diameter and was excavated using raise-boring. The ventilation shaft will consist of two keyed, conical sectioned, 2-m-thick concrete by 1.8 to 2.8 m diameter concrete segments confining a 5-m-thick assembly of pre-compacted clay-sand blocks. The concrete is a low pH concrete designed for repository use, which can develop a 70 MPa unconfined compressive strength after 28 days. It has a pH of less than 11 achieved by substitution of 75% of the cement powder with silica fume and ground silica so the likelihood of free calcium and an alkaline plume is

  2. 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.

  3. Burial trench dynamic compaction demonstration at a humid site

    International Nuclear Information System (INIS)

    This task has the objective of determining the degree of consolidation which can be achieved by dynamic compaction of a closed burial trench within a cohesive soil formation. A seven-year-old burial trench in Solid Waste Storage Area (SWSA) 6 of Oak Ridge National Laboratory (ORNL) was selected for this demonstration. This 251 m3 trench contained about 80 Ci of mixed radionuclides, mostly 90Sr, in 25 m3 of waste consisting of contaminated equipment, dry solids, and demolition debris. Prior to compaction, a total trench void space of 79 m3 was measured by pumping the trench full of water with corrections for seepage. Additional pre-compaction characterization included trench cap bulk density (1.68 kg/L), trench cap permeability (3 x 10-7 m/s), and subsurface waste/backfill hydraulic conductivity (>0.01 m/s). Compaction was achieved by repeatedly dropping a 4-ton steel-reinforced concrete cylinder from heights of 4 to 8 m using the whipline of a 70-ton crane. The average trench ground surface was depressed 0.79 m, with some sections over 2 m, yielding a surveyed volumetric depression which totaled to 64% of the measured trench void space. Trench cap (0 to 60 cm) bulk density and permeability were not affected by compaction indicating that the consolidation was largely subsurface. Neither surface nor airborne radioactive contamination were observed during repeated monitoring during the demonstration. Dynamic compaction was shown to be an excellent and inexpensive (i.e., about $20/m2) method to collapse trench void space, thereby hastening subsidence and stabilizing the land surface. 15 refs., 10 figs., 3 tabs

  4. Comparison of Apical Microleakage of Lateral Compaction Technique and Vertical Compaction Technique

    Institute of Scientific and Technical Information of China (English)

    Sahibzada Mohammad Noor; Xie Xiao Li

    2007-01-01

    Objective: The aim of this study was to assess the sealing ability of lateral compaction technique and vertical compaction technique using glucose penetration model. Glucose penetration model (GPM) has only twice been used earlier, hence the second aim of the study was to correlate the results of this study to other results and to validate the efficacy of GPM. Materals and Methods: Fifty three straight anterior human maxillary teeth were randomly divided into five groups.Root canals were prepared using crown down technique. Group A had fourteen teeth. They were compacted using vertical compaction technique. AH plus was used as root canal sealer. Group B had eight teeth. These were also compacted with vertical compaction but without AH plus. Group C had thirteen teeth. All the teeth in group C were compacted using lateral compaction using AH Plus. Group D had eight teeth. The teeth in this group were compacted using lateral compaction technique without AH plus. Group E had ten teeth. This group was assigned as negative control group. The specimen of the negative control group were completely coated with aryldite. The roots of the experimental groups were covered with aryldite, except for the root canal orifices, and apical apices. The coronal end of the decoronated tooth was connected to a plastic tube that contained 18% glucose solution. Leakage along the root filling was measured by the concentration of glucose in apical reservoir at 7, 14, 21 and 28 days intervals respectively after treatment. Results: Using repeated measure ANOVA, the leakage was significantly different among test groups A and C at 7, 14, 21 and 28 days interval respectively(P < 0.001). Data from Groups C and D also varied significantly. No statistical difference was found between groups A, B and D. Glucose concentrations at 21,28 days were higher than that at 7, 14 days in all of the four groups. Conclusion:The sealing ability of lateral compaction technique was found to be better than

  5. Central areolar choroidal dystrophy.

    NARCIS (Netherlands)

    Boon, C.J.F.; Klevering, B.J.; Cremers, F.P.M.; Zonneveld-Vrieling, M.N.; Theelen, T.; Hollander, A.I. den; Hoyng, C.B.

    2009-01-01

    OBJECTIVE: To describe the clinical characteristics, follow-up data and molecular genetic background in a large group of patients with central areolar choroidal dystrophy (CACD). DESIGN: Retrospective case series study. PARTICIPANTS: One hundred three patients with CACD from the Netherlands. METHODS

  6. Hot deformation behaviour and flow stress prediction of 7075 aluminium alloy powder compacts during compression at elevated temperatures

    OpenAIRE

    Jabbari Taleghani, M. A.; Salehi, M.; Ruiz Navas, Elisa María; Torralba, José Manuel

    2012-01-01

    In the present study, the hot deformation behaviour of 7075 aluminium alloy powder compacts was studied by performing hot compression tests on a Gleeble 3800 machine. The main objectives were to evaluate the effect of the relative green density on the hot deformation behaviour and to model and predict the hot deformation flow stress of powder compacts using constitutive equations. For this purpose, powder compacts with relative green densities ranging from 83 to 95%, which were prepared by un...

  7. Ultra-Compact Dwarfs in the Coma Cluster

    OpenAIRE

    Chiboucas, Kristin; Tully, R. Brent; Marzke, ; Ronald O.; Phillipps, Steve; Price, James; Peng, Eric; Trentham, Neil; Carter, David; Hammer, Derek

    2011-01-01

    We have undertaken a spectroscopic search for ultra compact dwarf galaxies (UCDs) in the dense core of the dynamically evolved, massive Coma cluster as part of the HST/ACS Coma Cluster Treasury Survey. UCD candidates were initially chosen based on color, magnitude, degree of resolution within the ACS images, and the known properties of Fornax and Virgo UCDs. Follow-up spectroscopy with Keck/LRIS confirmed 27 candidates as members of the Coma Cluster, a success rate > 60% for targeted objects ...

  8. Testing MOND with Ultra-Compact Dwarf Galaxies

    OpenAIRE

    Scarpa, Riccardo

    2005-01-01

    The properties of the recently discovered Ultra-Compact Dwarf Galaxies (UCDs) show that their internal acceleration of gravity is everywhere above a0, the MOdified Newtonian Dynamics (MOND) constant of gravity. MOND therefore makes the strong prediction that no mass discrepancy should be observed for this class of objects. This is confirmed by the few UCDs for which virial masses were derived. We argue that UCD galaxies represent a suitable test-bench for the theory, in the sense that even a ...

  9. Early object relations into new objects.

    Science.gov (United States)

    Downey, T W

    2001-01-01

    Two strands of change are suggested by this review, one maturational, the other therapeutic or developmental (Hartmann and Kris, 1945). By "maturational" I mean to suggest energies that infuse the individual from earliest life in a manner that includes object relations, but for the healthy exercise of which object relations per se need not be of central and crucial importance. Within wide limits such energies may be delayed until growth conditions prevail without significant distortion of certain of the organism's ego functions. Therapeutic change is analogous to developmental change in that both involve the crucial presence of another to release energies. In therapeutic change these are energies that have been repressed beyond the reach of developmental dynamics. In everyday development crisis and synthesis alternate in conjunction with new and emerging objects to add to the psychological structures brought to the fore by maturation. In many instances, as we see with John, over time and in a less focussed manner, developmental changes can approximate therapeutic change and visa versa. Freud-Dann in their "experiment" pursued one line, in which the equipmental delay brought on by extremely adverse living circumstances was redressed by providing an interpersonally enriching, loving, developmentally facilitating milieu. The sketches of individual children and John's subsequent story provide a perspective into what becomes the stuff of growth and what remains the stuff of neurosis. The developmental reserves and ego resilience of these children were impressive but probably not extraordinary. Usual growth ensued as soon as they were provided with the rich soil of Bulldogs Bank instead of the desert sand of the Tereszin concentration camp. However, no one can escape such adverse circumstances without having taken in the stuff of neurosis. Affects and percepts that were not assimilatable or even available to consciousness at the time remain buried in the unconscious

  10. 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.

  11. 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.

  12. Porewater chemistry in compacted bentonite

    International Nuclear Information System (INIS)

    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

  13. 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...... reinforcement arrangements under its own weight. Thus, SCC is not vibrated like conventional concrete. This drastically improves the working environment during construction, the productivity, and potentially improves the homogeneity and quality of the concrete. In addition SCC provides larger architectural...

  14. 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

  15. Flux stabilization in compact groups

    International Nuclear Information System (INIS)

    We consider the Born-Infeld action for symmetry-preserving, orientable D-branes in compact group manifolds. We find classical solutions that obey the flux quantization condition. They correspond to conformally invariant boundary conditions on the world sheet. We compute the spectrum of quadratic fluctuations and find agreement with the predictions of conformal field theory, up to a missing level-dependent truncation. Our results extend to D-branes with the geometry of twined conjugacy classes; they illustrate the mechanism of flux stabilization of D-branes. (author)

  16. Flux stabilization in compact groups

    CERN Document Server

    Bordalo, P; Schweigert, C; Bordalo, Pedro; Ribault, Sylvain; Schweigert, Christoph

    2001-01-01

    We consider the Born-Infeld action for symmetry-preserving, orientable D-branes in compact group manifolds. We find classical solutions that obey the flux quantization condition. They correspond to conformally invariant boundary conditions on the world sheet. We compute the spectrum of quadratic fluctuations and find agreement with the predictions of conformal field theory, up to a missing level-dependent truncation. Our results extend to D-branes with the geometry of twined conjugacy classes; they illustrate the mechanism of flux stabilization of D-branes.

  17. 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...

  18. The Importance of Compact Group Environments Over Cosmic Time

    Science.gov (United States)

    Wiens, Christopher; Johnson, Kelsey E.; Wenger, Trey; Xiao, Liting

    2016-01-01

    Galaxy interactions are critical to the evolution of the universe, influencing everything from star formation to the structure of the known universe. By studying galaxy interactions through computer simulations, we are able to observe what would normally take billions of years to progress. Compact groups are extremely dense clusters of at least three and typically no more than 10 galaxies interacting gravitationally that will often merge. These groups yield considerable information about galaxy interactions and mergers in dense environments but are difficult to observe at high redshifts. The Millennium Simulation is a massive n-body simulation of cold dark matter particles on a time scale equivalent to the known universe. It solves this problem as it allows us to study high redshift objects and timescales of billions of years. Using the simulation and what we know about compact groups from the Hickson surveys, we were able to examine the evolution of these groups through cosmic time. We built an algorithm that analyzed galaxies in the Millennium Simulation and tuned it to various selection parameters. We found that roughly 7% of galaxies in the present day were once compact groups, as most groups merged into a single elliptical galaxy. There is also an epoch of group existence at z ~ 1.5, slightly after the well-known epoch of star formation at z ~ 2. This offset provides meaningful insight into the evolution of compact groups and the influence they have had on the universe we see today.

  19. Compaction of an inceptisol caused by forest extraction with Skidder

    Directory of Open Access Journals (Sweden)

    José Carlos Pezzoni Filho

    2014-06-01

    Full Text Available The compaction due to machinery traffic causes damage to the soil that can interfere with the development of the root system of plants, resulting in decreased crop yields. The objective of this study was to evaluate the Inceptisol compaction caused by Skidder traffic in extraction of Pinus elliottii var. elliottii in secondary extension logging in tire tracks and stems, varying the frequency of tractor traffic. The tire tracks and stems were in the same line of traffic passage earlier, each located in their respective tracks. The study area was located in the municipality of Capão Bonito-SP, in cultivation of Pinus elliottii var. elliottii and samples were obtained from an area without traffic (control and applications with 1, 2, 3, 4 and 5 Skidder passes in two layers, 0.00 to 0.05 and 0.10 - 0.15 m depth. The results showed that there was additional compaction by each passage of the Skidder, being higher in the layer of 0.00 to 0.05 m depth. Soil compaction was more pronounced under lower water content in the soil, being contrary to the expected.

  20. Formulation and Evaluation of Liquisolid Compacts for Olmesartan Medoxomil

    Directory of Open Access Journals (Sweden)

    Shailesh T. Prajapati

    2013-01-01

    Full Text Available Olmesartan medoxomil is an angiotensin type II receptor blocker, antihypertensive agent, administered orally. It is highly lipophilic (log P 5.5 and a poorly water-soluble drug with absolute bioavailability of 26%. The poor dissolution rate of water-insoluble drugs is still a major problem confronting the pharmaceutical industry. The objective of the present investigation was to develop liquisolid compacts for olmesartan medoxomil to improve the dissolution rate. Liquisolid compacts were prepared using Acrysol El 135 as a solvent, Avicel PH 102, Fujicalin and Neusilin as carrier materials, and Aerosil as coating material in different ratios. The interaction between drug and excipients was characterized by DSC and FT-IR studies, which showed that there is no interaction between drug and excipients. The powder characteristics were evaluated by different flow parameters to comply with pharmacopoeial limits. The dissolution studies for liquisolid compacts and conventional formulations were carried out, and it was found that liquisolid compacts with 80% w/w of Acrysol EL 135 to the drug showed significant higher drug release rates than conventional tablets. Amongst carriers used Fujicalin and Neusilin were found to be more effective carrier materials for liquid adsorption.

  1. Compact Visualisation of Video Summaries

    Directory of Open Access Journals (Sweden)

    Ćalić Janko

    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.

  2. Molecular Gas in Compact Galaxies

    CERN Document Server

    Israel, F P

    2005-01-01

    New observations of 11 compact galaxies in the 12CO J=2-1 and J=3-2 transitions and literature data have been used to construct accurate line ratios in matched beams allowing LVG modelling of physical parameters. Fitting a single gas component to observed line ratios tends to produce physically unrealistic results, and is often not possible at all. Much better results are obtained by modelling two distinct gas components. The molecular gas is usually warm (T(kin)=50-150 K) and at least partially dense (n(H2)>3000 cm3). Most of the gas-phase carbon in these galaxies is in atomic form; only a small fraction (5%) is in carbon monoxide. Beam-averaged CO column densities are low, typically 10(16) cm2 but molecular hydrogen column densities are high, of the order of 10(22) cm2 and confirm large CO-to-H2 conversion factors, typically X = 10(21)-10(22) cm2(K kms-1) found in low-metallicity environments by other methods. From CO spectroscopy, three different types of molecular environment are distinguished in compact ...

  3. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    International Nuclear Information System (INIS)

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential

  4. 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

  5. Anisotropic generalization of Matese & Whitman solution for compact star models in general relativity

    Science.gov (United States)

    Dayanandan, Baiju; Maurya, S. K.; Gupta, Y. K.; Smitha, T. T.

    2016-05-01

    We present a detailed investigation of the stability of anisotropic compact star models by introducing Matese and Whitman (Phys. Rev. D 11:1270, 1980) solution in general relativity. We have particularly looked into the detailed investigation of the measurements of basic physical parameters such as radial pressure, tangential pressure, energy density, red shift, sound velocity, masses and radii are affected by unknown effects such as loss, accretion and diffusion of mass. Those give insight into the characteristics of the compact astrophysical object with anisotropic matter distribution as well as the physical reality. The results obtained for the physical feature of compact stars such as, Her. X-1, RXJ 1856-37, SAX J1808.4-3658(SS2) and SAX J1808.4-3658(SS1) are compared to the recently observed massive compact object.

  6. Compact high-resolution gamma-ray computed tomography system for multiphase flow studies

    Science.gov (United States)

    Bieberle, A.; Nehring, H.; Berger, R.; Arlit, M.; Härting, H.-U.; Schubert, M.; Hampel, U.

    2013-03-01

    In this paper, a compact high-resolution gamma-ray Computed Tomography (CompaCT) measurement system for multiphase flow studies and tomographic imaging of technical objects is presented. Its compact and robust design makes it particularly suitable for studies on industrial facilities and outdoor applications. Special care has been given to thermal ruggedness, shock resistance, and radiation protection. Main components of the system are a collimated 137Cs isotopic source, a thermally stabilised modular high-resolution gamma-ray detector arc with 112 scintillation detector elements, and a transportable rotary unit. The CompaCT allows full CT scans of objects with a diameter of up to 130 mm and can be operated with any tilting angle from 0° (horizontal) to 90° (vertical).

  7. The Future Concrete: Self-Compacting Concrete

    OpenAIRE

    Liana Iureş; Corneliu Bob

    2010-01-01

    The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

  8. 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

  9. Positron Annihilation Lifetimes in Compacted Iron Powder

    International Nuclear Information System (INIS)

    The positron annihilation lifetime (PAL) spectroscopy has been performed on iron powder as a function of compacted powder load. The ortho-positronium lifetime increases from 1.45 to 2.55 ns with compaction load increment from 30 to 50 tons. By increasing the compaction load, the ultimate stress and hardness increases and the ductlity decreases. The result shows that there is a direct correlation between the void size and the load decrement. These results will be presented and discussed

  10. 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...

  11. A Computer Verified Theory of Compact Sets

    OpenAIRE

    O'Connor, Russell

    2008-01-01

    Compact sets in constructive mathematics capture our intuition of what computable subsets of the plane (or any other complete metric space) ought to be. A good representation of compact sets provides an efficient means of creating and displaying images with a computer. In this paper, I build upon existing work about complete metric spaces to define compact sets as the completion of the space of finite sets under the Hausdorff metric. This definition allowed me to quickly develop a computer ve...

  12. Aggregate water stability of sandy and clayey loam soils differently compacted with and without wheat plants

    OpenAIRE

    Bazzoffi P.; Balashov E.

    2003-01-01

    The objectives of our studies were to: 1) estimate the effects of compaction of sandy loam and clayey loam soils on growth parameters of winter wheat plants, 2) evaluate the resilien- ce capacity of the root system for the water-stable aggregation of compacted soils. Soil samples at field capacity were placed into pots with an initial bulk density of 1.2 Mg m-3 and compacted with ground contact pressures of 51, 103 and 154 kPa using a hydraulic compressor. Five plants in each pot were allowed...

  13. 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.

  14. Soil compaction and growth of woody plants

    International Nuclear Information System (INIS)

    Although soil compaction in the field may benefit or inhibit the growth of plants, the harmful effects are much more common. This paper emphasizes the deleterious effects of predominantly high levels of soil compaction on plant growth and yield. High levels of soil compaction are common in heavily used recreation areas, construction sites, urban areas, timber harvesting sites, fruit orchards, agroforestry systems and tree nurseries. Compaction can occur naturally by settling or slumping of soil or may be induced by tillage tools, heavy machinery, pedestrian traffic, trampling by animals and fire. Compaction typically alters soil structure and hydrology by increasing soil bulk density; breaking down soil aggregates; decreasing soil porosity, aeration and infiltration capacity; and by increasing soil strength, water runoff and soil erosion. Appreciable compaction of soil leads to physiological dysfunctions in plants. Often, but not always, reduced water absorption and leaf water deficits develop. Soil compaction also induces changes in the amounts and balances of growth hormones in plants, especially increases in abscisic acid and ethylene. Absorption of the major mineral nutrients is reduced by compaction of both surface soils and subsoils. The rate of photosynthesis of plants growing in very compacted soil is decreased by both stomatal and non-stomatal inhibition. Total photosynthesis is reduced as a result of smaller leaf areas. As soils become increasingly compacted respiration of roots shifts toward an anaerobic state. Severe soil compaction adversely influences regeneration of forest stands by inhibiting seed germination and growth of seedlings, and by inducing seedling mortality. Growth of woody plants beyond the seedling stage and yields of harvestable plant products also are greatly decreased by soil compaction because of the combined effects of high soil strength, decreased infiltration of water and poor soil aeration, all of which lead to a decreased

  15. Sound objects – Auditory objects – Musical objects

    DEFF Research Database (Denmark)

    Hjortkjær, Jens

    2016-01-01

    The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects’. In this...... paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent in the...

  16. Sound objects – Auditory objects – Musical objects

    DEFF Research Database (Denmark)

    Hjortkjær, Jens

    2015-01-01

    The auditory system transforms patterns of sound energy into perceptual objects but the precise definition of an ‘auditory object’ is much debated. In the context of music listening, Pierre Schaeffer argued that ‘sound objects’ are the fundamental perceptual units in ‘musical objects’. In this...... paper, I review recent neurocognitive research suggesting that the auditory system is sensitive to structural information about real-world objects. Instead of focusing solely on perceptual sound features as determinants of auditory objects, I propose that real-world object properties are inherent in the...

  17. Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Qingyang [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Wang, Shi [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Ma, Tianyu, E-mail: maty@tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China); Wu, Jing; Liu, Hui; Xu, Tianpeng; Xia, Yan; Fan, Peng; Lyu, Zhenlei; Liu, Yaqiang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing 100084 (China)

    2015-06-21

    PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance.

  18. Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

    International Nuclear Information System (INIS)

    PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance

  19. The Next Generation Virgo Cluster Survey. VI. The Kinematics of Ultra-compact Dwarfs and Globular Clusters in M87

    CERN Document Server

    Zhang, Hong-Xin; Cote, Patrick; Liu, Chengze; Ferrarese, Laura; Cuillandre, Jean-Charles; Caldwell, Nelson; Gwyn, Stephen D J; Jordan, Andres; Lancon, Ariane; Li, Biao; Munoz, Roberto P; Puzia, Thomas H; Bekki, Kenji; Blakeslee, John; Boselli, Alessandro; Drinkwater, Michael J; Duc, Pierre-Alain; Durrell, Patrick; Emsellem, Eric; Firth, Peter; Sanchez-Janssen, Ruben

    2015-01-01

    The origin of ultra-compact dwarfs (UCDs)--objects larger and more massive than typical globular clusters (GCs), but more compact than typical dwarf galaxies--has been hotly debated in the 15 years since their discovery. Even whether UCDs should be considered galactic in origin, or simply the most extreme GCs, is not yet settled. We present the dynamical properties of 97 spectroscopically confirmed UCDs (rh >~10 pc) and 911 GCs associated with central cD galaxy of the Virgo cluster, M87. Our UCDs, of which 89% have M_star > ~2X10^6 M_sun and 92% are as blue as the classic blue GCs, nearly triple the sample of previous confirmed Virgo UCDs, providing by far the best opportunity for studying the global dynamics of a UCD system. We found that (1) UCDs have a surface number density profile that is shallower than that of the blue GCs in the inner ~ 70 kpc and as steep as that of the red GCs at larger radii; (2) UCDs exhibit a significantly stronger rotation than the GCs, and the blue GCs seem to have a velocity fi...

  20. Performance evaluation of a compact PET/SPECT/CT tri-modality system for small animal imaging applications

    Science.gov (United States)

    Wei, Qingyang; Wang, Shi; Ma, Tianyu; Wu, Jing; Liu, Hui; Xu, Tianpeng; Xia, Yan; Fan, Peng; Lyu, Zhenlei; Liu, Yaqiang

    2015-06-01

    PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted on the system and inserted into the detector ring in SPECT imaging mode. A cone-beam CT consisting of a micro focus X-ray tube and a CMOS detector is implemented. The detailed design and the performance evaluations are reported in this paper. In PET imaging mode, the measured NEMA based spatial resolution is 2.12 mm (FWHM), and the sensitivity at the central field of view (CFOV) is 3.2%. The FOV size is 50 mm (∅)×100 mm (L). The SPECT has a spatial resolution of 1.32 mm (FWHM) and an average sensitivity of 0.031% at the center axial, and a 30 mm (∅)×90 mm (L) FOV. The CT spatial resolution is 8.32 lp/mm @10%MTF, and the contrast discrimination function value is 2.06% with 1.5 mm size cubic box object. In conclusion, a compact, tri-modality PET/SPECT/CT system was successfully built with low cost and high performance.

  1. The influence of skidding operations on forest soil properties and soil compaction in Bartin, Turkey.

    OpenAIRE

    BOLAT, İlyas; MELEMEZ, Kenan; Özer, Davut

    2015-01-01

    Mechanized harvesting operations yield high productivity; however, it damages forest soils seriously. The objective of this study is to determine the impacts of skidding operations ontopsoil physical and chemical properties at four different forest floors (tractor road, skid trail, harvesting area and undisturbed area) after a harvesting season. Also, the relationship between soil compaction and soil moisture of these areas were analysed. Soil compaction was estimated with the values of topso...

  2. Experimental study of soil compaction effects on GPR signals

    Science.gov (United States)

    Wang, Ping; Hu, Zhenqi; Zhao, Yanling; Li, Xinju

    2016-03-01

    Mechanical operations may lead to soil compaction hazard in land consolidation projects. Aiming to quantitatively guarantee soil compaction status with ground penetrating radar (GPR), we should clearly understand the relationship between bulk density/penetration resistance (PR) and GPR signals. This research adopted GPR with a central frequency of 500 MHz and the experimental design with laboratory test and outdoor test. Because soil dielectric constant receives combination influence of soil properties, statistical methods were used to analyze the influence of soil bulk density on electromagnetic wave velocity. Significant correlation exists between electromagnetic wave velocity and bulk density, with a partial correlation coefficient of 0.882 and two-tailed significance of 0.020. While soil dielectric constant strongly depends on soil water content, the growing of soil bulk density usually reduces free water content, increases bound water content and finally influences GPR signals. The results also showed that high soil PR value accompanied with low amplitude values of electromagnetic wave and fast decay rate of the amplitude back to noise level. More experimental data would be acquired for accurate quantification between soil compaction and GPR signals with statistic methods in the future research.

  3. Compact anti-radon facility

    Energy Technology Data Exchange (ETDEWEB)

    Fajt, L.; Kouba, P.; Mamedov, F.; Smolek, K.; Štekl, I., E-mail: ivan.stekl@utef.cvut.cz [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horská 3a/22, 128 00 Prague 2 (Czech Republic); Fojtík, P.; Hýža, M.; Hůlka, J.; Jílek, K. [SÚRO (NRPI) National Radiation Protection Institute, Bartoškova 1450/28, 140 00 Prague 4 (Czech Republic); Stoček, P.; Veselý, J. [ATEKO a.s., Resslova 956/13, 501 01Hradec Králové, Czech Republic. (Czech Republic); Busto, J. [CPPM, Universite de Marseille, CNRS/IN2P3, F-13288 Marseille (France)

    2015-08-17

    Suppression of radon background is one of main tasks in ultra-low background experiments. The most promising technique for suppression of radon is its adsorption on charcoal. Within the frame of the NEMO-3 experiment, radon trapping facility (RTF) was installed in Modane underground laboratory in 2004. Based on long-term experience with this facility a new compact transportable anti-radon facility was constructed in cooperation among IEAP CTU, SÚRO and ATEKO company. The device provides 20m{sup 3}/h of purified air (air radon activity at the output ∼10mBq/m{sup 3}). The basic features and preliminary results of anti-radon device testing are presented.

  4. Compact Quantum Cascade Laser Transmitter

    Energy Technology Data Exchange (ETDEWEB)

    Anheier, Norman C.; Hatchell, Brian K.; Gervais, Kevin L.; Wojcik, Michael D.; Krishnaswami, Kannan; Bernacki, Bruce E.

    2009-04-01

    ): In this paper we present design considerations, thermal and optical modeling results, and device performance for a ruggedized, compact laser transmitter that utilizes a room temperature quantum cascade (QC) laser source. The QC laser transmitter is intended for portable mid-infrared (3-12 µm) spectroscopy applications, where the atmospheric transmission window is relatively free of water vapor interference and where the molecular rotational vibration absorption features can be used to detect and uniquely identify chemical compounds of interest. Initial QC laser-based sensor development efforts were constrained by the complications of cryogenic operation. However, improvements in both QC laser designs and fabrication processes have provided room-temperature devices that now enable significant miniaturization and integration potential for national security, environmental monitoring, atmospheric science, and industrial safety applications.

  5. 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.

  6. 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

  7. Compact Microwave Fourier Spectrum Analyzer

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitry

    2009-01-01

    A compact photonic microwave Fourier spectrum analyzer [a Fourier-transform microwave spectrometer, (FTMWS)] with no moving parts has been proposed for use in remote sensing of weak, natural microwave emissions from the surfaces and atmospheres of planets to enable remote analysis and determination of chemical composition and abundances of critical molecular constituents in space. The instrument is based on a Bessel beam (light modes with non-zero angular momenta) fiber-optic elements. It features low power consumption, low mass, and high resolution, without a need for any cryogenics, beyond what is achievable by the current state-of-the-art in space instruments. The instrument can also be used in a wide-band scatterometer mode in active radar systems.

  8. 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

  9. 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

  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 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.

  12. Quasi-objects, Cult Objects and Fashion Objects

    DEFF Research Database (Denmark)

    Andersen, Bjørn Schiermer

    2011-01-01

    This article attempts to rehabilitate the concept of fetishism and to contribute to the debate on the social role of objects as well as to fashion theory. Extrapolating from Michel Serres’ theory of the quasi-objects, I distinguish two phenomenologies possessing almost opposite characteristics. T...

  13. Continued evaluation of compact heat exchangers for OTEC application. Interim progress report, February 15, 1977--August 15, 1977

    Energy Technology Data Exchange (ETDEWEB)

    McGowan, J.G.; Heronemus, W.E.

    1977-08-01

    Progress on the continued UMass technical evaluation of compact heat exchangers for OTEC applications is summarized. Objectives of this study include: (1) Analytical and experimental evaluation of the performance characteristics of compact heat exchangers (using ammonia as a working fluid) over the entire range of OTEC system conditions, (2) An evaluation of the applicable manufacturing processes, maintenance requirements and arrangement concepts for large scale compact heat exchangers with specific emphasis on their total economics. This progress report also includes a technical report on compact heat exchanger design information for OTEC application. Contained in this report are a review of previous compact heat exchanger work, a literature review of applicable two phase evaporating and condensing technical publications, and recommendations for compact heat exchanger analytical design procedure.

  14. Learning Object Repositories

    Science.gov (United States)

    Lehman, Rosemary

    2007-01-01

    This chapter looks at the development and nature of learning objects, meta-tagging standards and taxonomies, learning object repositories, learning object repository characteristics, and types of learning object repositories, with type examples. (Contains 1 table.)

  15. SOCRATES Invades Central Europe

    Directory of Open Access Journals (Sweden)

    Joseph Slowinski

    1998-04-01

    Full Text Available The objective of this article is to explore the current reality faced by higher education students in Central and Eastern Europe and to draw out the implications of this current reality for policy makers in the future. In the article, I explore the influence of transnational corporations' training programs on education as it currently pertains to Central and Eastern European higher education and employment. In addition, multinational corporate entities exercise influence on European Union policy through the role of lobby organizations and activities. I explore the influence of these practices on education with an emphasis on the emerging importance of Western language skills. In addition, I focus on the European Union and its efforts to expand into Central and Eastern Europe in order to provide a focal point for analysis.

  16. Model-independent inference on compact-binary observations

    CERN Document Server

    Mandel, Ilya; Colonna, Andrea; Stevenson, Simon; Tiňo, Peter; Veitch, John

    2016-01-01

    The recent advanced LIGO detections of gravitational waves from merging binary black holes enhance the prospect of exploring binary evolution via gravitational-wave observations of a population of compact-object binaries. In the face of uncertainty about binary formation models, model-independent inference provides an appealing alternative to comparisons between observed and modelled populations. We describe a procedure for clustering in the multi-dimensional parameter space of observations that are subject to significant measurement errors. We apply this procedure to a mock data set of population-synthesis predictions for the masses of merging compact binaries convolved with realistic measurement uncertainties, and demonstrate that we can accurately distinguish subpopulations of binary neutron stars, binary black holes, and mixed black hole -- neutron star binaries.

  17. Compact toroid development: activity plan for field reversed configurations

    International Nuclear Information System (INIS)

    This document contains the description, goals, status, plans, and approach for the investigation of the properties of a magnetic configuration for plasma confinement identified as the field reversed configuration (FRC). This component of the magnetic fusion development program has been characterized by its potential for physical compactness and a flexible range of output power. The included material represents the second phase of FRC program planning. The first was completed in February 1983, and was reported in DOE/ER-0160; Compact Toroid Development. This planning builds on that previous report and concentrates on the detailed plans for the next several years of the current DOE sponsored program. It has been deliberately restricted to the experimental and theoretical efforts possible within the present scale of effort. A third phase of this planning exercise will examine the subsequent effort and resources needed to achieve near term (1987 to 1990) FRC technical objectives

  18. The environment of nearby Blue Compact Dwarf Galaxies

    CERN Document Server

    Lopez-Sanchez, Angel R; van Eymeren, Janine; Esteban, Cesar; Popping, Attila; Hibbard, John

    2009-01-01

    We are obtaining deep multiwavelength data of a sample of nearby blue compact dwarf galaxies (BCDGs) combining broad-band optical/NIR and H$\\alpha$ photometry, optical spectroscopy and 21-cm radio observations. Here we present HI results obtained with the Australia Telescope Compact Array for some BCDGs, all showing evident interaction features in their neutral gas component despite the environment in which they reside. Our analysis strongly suggests that interactions with or between low-luminosity dwarf galaxies or HI clouds are the main trigger mechanism of the star-forming bursts in BCDGs; however these dwarf objects are only detected when deep optical images and complementary HI observations are performed. Are therefore BCDGs real isolated systems?

  19. Beyond the Chandrasekhar limit: Structure and formation of compact stars

    Indian Academy of Sciences (India)

    Dipankar Bhattacharya

    2011-07-01

    The concept of limiting mass, introduced by Chandrasekhar in case of white dwarfs, plays an important role in the formation and stability of compact objects such as neutron stars and black holes. Like white dwarfs, neutron stars have their own mass limit, and a compact configuration would progress from one family to the next, more dense one once a mass limit is crossed. The mass limit of neutron stars depends on the nature of nuclear forces at very high density, which has so far not been determined conclusively. This article reviews how observational determinations of the properties of neutron stars are starting to impose significant constraints on the state of matter at high density

  20. The Environment of Massive Quiescent Compact Galaxies at $0.1

    CERN Document Server

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

    2015-01-01

    We use Hectospec mounted on the 6.5-meter MMT to carry out a redshift survey of red ($r-i>0.2$, $g-r>0.8$, $r<21.3$) galaxies in the COSMOS field to measure the environments of massive compact galaxies at intermediate redshift. The complete magnitude limited survey includes redshifts for 1766 galaxies with $r < 20.8$ covering the central square degree of the field; 65% of the redshifts in this sample are new. We select a complete magnitude limited quiescent sample based on the rest-frame $UVJ$ colors. When the density distribution is sampled on a scale of 2 Mpc massive compact galaxies inhabit systematically denser regions than the parent quiescent galaxy population. Non-compact quiescent galaxies with the same stellar masses as their compact counterparts populate a similar distribution of environments. Thus the massive nature of quiescent compacts accounts for the environment dependence and appears fundamental to their history.

  1. On compact multipliers of topological algebras

    International Nuclear Information System (INIS)

    It is shown that if the maximal ideal space Δ(A) of a semisimple commutative complete metrizable locally convex algebra contains no isolated points, then every compact multiplier is trivial. Particularly, compact multipliers on semisimple commutative Frechet algebras whose maximal ideal space has no isolated points are identically zero. (author). 5 refs

  2. 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...

  3. Physics of compact ignition tokamak designs

    International Nuclear Information System (INIS)

    Models for predicting plasma performance in compact ignition experiments are constructed on the basis of theoretical and empirical constraints and data from tokamak experiments. Emphasis is placed on finding transport and confinement models which reproduce results of both ohmically and auxiliary heated tokamak data. Illustrations of the application of the models to compact ignition designs are given

  4. Strength of field compacted clayey embankments

    Science.gov (United States)

    Liang, Y.; Lovell, C. W.

    1982-02-01

    The shearing behavior of a plastic Indiana clay (St. Croix) was studied for both laboratory and field compaction. This interim report deals with the field compacted phase. The strength tests were performed by unconsolidated undrained (UU) and saturated consolidated undrained (CIU) triaxials. These were run at various confining pressures to approximate the end of construction and long term conditions at several embankment depths.

  5. 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.

  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. Compact Process Development at Babcock and Wilcox

    International Nuclear Information System (INIS)

    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.

  9. 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

  10. The coeffective cohomology for compact symplectic nilmanifolds

    International Nuclear Information System (INIS)

    The coeffective cohomology of symplectic manifolds was recently introduced by Bouche in [3]. He has proved that the coeffective cohomology and the truncated de Rham cohomology groups of a 2n-dimensional compact Kahler manifold are siomorphic, for degree p>- n+1. In this paper we show that the results does not hold for arbitrary compact symplectic nor indefinite Kahler manifolds. 16 refs

  11. Computing Decoupled Residuals for Compact Disc Players

    DEFF Research Database (Denmark)

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

    2006-01-01

    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...

  12. 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.

  13. Relative Near PS-Compact L-subsets

    OpenAIRE

    HE Wei-min

    2010-01-01

    In this paper the new concept of relative near PS-compactness in L-fuzzy topological spaces is introduced. The relative near PS-compactness is described with a-net , r-ps-cover, r-finite intersection property. The relationship between relative near PS-compactness and near PS-compactness is in vestigated. It is found that near PS-compactness implies relative near PS-compactness and every LF-set of near PS-compact space is relative near PS-compact. The relative near PS-compactness possess the f...

  14. Compact electrically detected magnetic resonance setup

    International Nuclear Information System (INIS)

    Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a “large-scale” state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule

  15. Behavior of compacted clay-concrete interface

    Institute of Scientific and Technical Information of China (English)

    R.R. SHAKIR; Jungao ZHU

    2009-01-01

    Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared.Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface rough-ness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

  16. Compactly accessible categories and quantum key distribution

    CERN Document Server

    Heunen, Chris

    2008-01-01

    Compact categories have lately seen renewed interest via applications to quantum physics. Being essentially finite-dimensional, they cannot accomodate (co)limit-based constructions. For example, they cannot capture protocols such as quantum key distribution, that rely on the law of large numbers. To overcome this limitation, we introduce the notion of a compactly accessible category, relying on the extra structure of a factorisation system. This notion allows for infinite dimension while retaining key properties of compact categories: the main technical result is that the choice-of-duals functor on the compact part extends canonically to the whole compactly accessible category. As an example, we model a quantum key distribution protocol and prove its correctness categorically.

  17. Secondary structures in long compact polymers.

    Science.gov (United States)

    Oberdorf, Richard; Ferguson, Allison; Jacobsen, Jesper L; Kondev, Jané

    2006-11-01

    Compact polymers are self-avoiding random walks that visit every site on a lattice. This polymer model is used widely for studying statistical problems inspired by protein folding. One difficulty with using compact polymers to perform numerical calculations is generating a sufficiently large number of randomly sampled configurations. We present a Monte Carlo algorithm that uniformly samples compact polymer configurations in an efficient manner, allowing investigations of chains much longer than previously studied. Chain configurations generated by the algorithm are used to compute statistics of secondary structures in compact polymers. We determine the fraction of monomers participating in secondary structures, and show that it is self-averaging in the long-chain limit and strictly less than 1. Comparison with results for lattice models of open polymer chains shows that compact chains are significantly more likely to form secondary structure. PMID:17279930

  18. High velocity compact clouds in the sagittarius C region

    International Nuclear Information System (INIS)

    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.°61 < l < –0.°27, –0.°29 < b < 0.°04) in the HCN J = 4-3, 13CO J = 3-2, and H13CN J = 1-0 lines with the ASTE 10 m and NRO 45 m telescopes, detecting bright emission with 80-120 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 a 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 and CO–0.40–0.22 are (0.8-2) × 1049 erg and (1-4) × 1049 erg, respectively. We propose several interpretations of their broad emission: collision between clouds associated with the shells, bipolar outflow, expansion driven by supernovae (SNe), and rotation around a dark massive object. These scenarios cannot be discriminated because of the insufficient angular resolution of our data, though the absence of a visible energy source associated with the HVCCs seems to favor the cloud-cloud collision scenario. Kinetic energies of the two molecular shells are 1 × 1051 erg and 0.7 × 1051 erg, which can be furnished by multiple SN or hypernova explosions in 2 × 105 yr. These shells are candidates of molecular superbubbles created after past active star formation.

  19. Measuring Central Bank Communication:

    OpenAIRE

    David Lucca; Francesco Trebbi

    2008-01-01

    We present a new automated, objective and intuitive scoring method to measure the content of central bank communication about future policy rate moves. We apply the methodology to statements released by the Federal Open Market Commitee (FOMC) after monetary policy meetings. Using high-frequency financial data, we find that yields on short-term risk-free nominal rates respond both to changes in policy rates and the content of the statements, whereas, medium and long-term rates only respond to ...

  20. Centralized Allocation in Multiple Markets

    DEFF Research Database (Denmark)

    Monte, Daniel; Tumennasan, Norovsambuu

    | generalizations of Gale's Top Trading Cycles mechanism. We study the centralized allocation that takes place in multiple markets. For example, the assignment of multiple types of indivisible objects; or the assignment of objects in successive periods. We show that the set of strategy-proof, Pareto efficient and...

  1. CENTRAL PLATEAU REMEDIATION

    Energy Technology Data Exchange (ETDEWEB)

    ROMINE, L.D.

    2006-02-01

    A systematic approach to closure planning is being implemented at the Hanford Site's Central Plateau to help achieve the goal of closure by the year 2035. The overall objective of Central Plateau remediation is to protect human health and the environment from the significant quantity of contaminated material that resulted from decades of plutonium production in support of the nation's defense. This goal will be achieved either by removing contaminants or placing the residual contaminated materials in a secure configuration that minimizes further migration to the groundwater and reduces the potential for inadvertent intrusion into contaminated sites. The approach to Central Plateau cleanup used three key concepts--closure zones, closure elements, and closure process steps--to create an organized picture of actions required to complete remediation. These actions were merged with logic ties, constraints, and required resources to produce an integrated time-phased schedule and cost profile for Central Plateau closure. Programmatic risks associated with implementation of Central Plateau closure were identified and analyzed. Actions to mitigate the most significant risks are underway while high priority remediation projects continue to make progress.

  2. CENTRAL PLATEAU REMEDIATION

    International Nuclear Information System (INIS)

    A systematic approach to closure planning is being implemented at the Hanford Site's Central Plateau to help achieve the goal of closure by the year 2035. The overall objective of Central Plateau remediation is to protect human health and the environment from the significant quantity of contaminated material that resulted from decades of plutonium production in support of the nation's defense. This goal will be achieved either by removing contaminants or placing the residual contaminated materials in a secure configuration that minimizes further migration to the groundwater and reduces the potential for inadvertent intrusion into contaminated sites. The approach to Central Plateau cleanup used three key concepts--closure zones, closure elements, and closure process steps--to create an organized picture of actions required to complete remediation. These actions were merged with logic ties, constraints, and required resources to produce an integrated time-phased schedule and cost profile for Central Plateau closure. Programmatic risks associated with implementation of Central Plateau closure were identified and analyzed. Actions to mitigate the most significant risks are underway while high priority remediation projects continue to make progress

  3. Peculiar compact stellar systems in the Fornax cluster

    CERN Document Server

    Wittmann, Carolin; Pasquali, Anna; Hilker, Michael; Grebel, Eva K

    2016-01-01

    We search for hints to the origin and nature of compact stellar systems in the magnitude range of ultracompact dwarf galaxies in deep wide-field imaging data of the Fornax cluster core. We visually investigate a large sample of 355 spectroscopically confirmed cluster members with V-band equivalent magnitudes brighter than -10 mag for faint extended structures. Our data reveal peculiar compact stellar systems, which appear asymmetric or elongated from their outer light distribution. We characterize the structure of our objects by quantifying their core concentration, as well as their outer asymmetry and ellipticity. For the brighter objects of our sample we also investigate their spatial and phase-space distribution within the cluster. We argue that the distorted outer structure alone that is seen for some of our objects, is not sufficient to decide whether these systems have a star cluster or a galaxy origin. However, we find that objects with low core concentration and high asymmetry (or high ellipticity) ar...

  4. 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

  5. Investigating radial wire array Z pinches as a compact x-ray source on the Saturn generator

    International Nuclear Information System (INIS)

    Radial wire array z pinches, where wires are positioned radially outward from a central cathode to a concentric anode, can act as a compact bright x-ray source that could potentially be used to drive a hohlraum. Experiments were performed on the 7-MA Saturn generator using radial wire arrays. These experiments studied a number of potential risks in scaling radial wire arrays up from the 1-MA level, where they have been shown to be a promising compact X-ray source. Data indicates that at 7 MA, radial wire arrays can radiate ~9 TW with 10-ns full-width at half-maximum from a compact pinch

  6. Soil Compaction and Oil Palm (Elaeis guineensis Yield in a Clay Textured Soil

    Directory of Open Access Journals (Sweden)

    Zuraidah Yahya

    2010-01-01

    Full Text Available Problem statement: The impacts of soil compaction on crop yields have been studied extensively by soil scientists due to declining soil productivity associated with mechanisation. However, a relationship between machine-induced soil compaction and oil palm (Elaeis guineensis yield is unclear. Therefore, the objectives of this study were to determine the effects of mechanization on soil physical properties and the influence on oil palm yield. Approach: The palms were planted in Bernam series soil which is clay textured. Compaction treatments were imposed for 6 consecutive years. Comparisons were made between the effects of soil compaction caused by different trailer weights and monthly transportation frequency. Results: The results showed a beneficial effect of soil compaction on the oil palm yield. It significantly increased the yield with increased mean soil bulk density. The transportation frequency played a greater role than the trailer weight. After six years of soil compaction, there was a positive relationship between mean soil bulk density, porosity and oil palm yield. Conclusion: Thus compaction may not often be a problem.

  7. Europa central

    Directory of Open Access Journals (Sweden)

    Karel BARTOSEK

    2010-02-01

    Full Text Available La investigación francesa continúa interesándose por Europa Central. Desde luego, hay límites a este interés en el ambiente general de mi nueva patria: en la ignorancia, producto del largo desinterés de Francia por este espacio después de la Segunda Guerra Mundial, y en el comportamiento y la reflexión de la clase política y de los medios de comunicación (una anécdota para ilustrar este ambiente: durante la preparación de nuestro coloquio «Refugiados e inmigrantes de Europa Central en el movimiento antifascista y la Resistencia en Francia, 1933-1945», celebrado en París en octubre de 1986, el problema de la definición fue planteado concreta y «prácticamente». ¡Y hubo entonces un historiador eminente, para quién Alemania no formaría parte de Europa Central!.

  8. Compact, harmonic multiplying gyrotron amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Guo, H.Z.; Granatstein, V.L.; Antonsen, T.M. Jr.; Levush, B.; Tate, J.; Chen, S.H. [Univ. of Maryland, College Park, MD (United States). Inst. for Plasma Research

    1995-12-31

    A compact, harmonic multiplying gyrotron traveling wave amplifier is being developed. The device is a three-stage tube with the output section running as a fourth harmonic gyro-TWT, the input section running as a fundamental gyro-TWT, and the middle operating at the second harmonic of the cyclotron frequency. Radiation is suppressed by servers between the sections. The operating beam of the tube is produced by a magnetron injection gun (MIG). A TE{sub 0n} mode selective interaction circuit consisting of mode converters and a filter waveguide is employed for both input and output sections to solve the mode competition problem, which is pervasive in gyro-TWT operation. The input section has an input coupler designed as a TE{sub 0n} mode launcher. It excites a signal at the fundamental cyclotron frequency (17.5 GHz), which is amplified in the first TWT interaction region. So far the device is similar to a two-stage harmonic gyro-TWT. The distinction is that in the three-stage device the second section will be optimized not for output power but for fourth harmonic bunching of the beam. A gyroklystron amplifier has also been designed. The configuration is similar to the gyro-TWT but with the traveling wave interaction structures replaced by mode selective special complex cavities. Cold test results of the wideband input coupler and the TE{sub 0n} mode selective interaction circuit have been obtained.

  9. 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

  10. Spherically symmetric charged compact stars

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, S.K. [University of Nizwa, Department of Mathematical and Physical Sciences, College of Arts and Science, Nizwa (Oman); Gupta, Y.K. [Jaypee Institute of Information Technology University, Department of Mathematics, Noida, Uttar Pradesh (India); Ray, Saibal [Government College of Engineering and Ceramic Technology, Department of Physics, Kolkata, West Bengal (India); Chowdhury, Sourav Roy [Seth Anandaram Jaipuria College, Department of Physics, Kolkata, West Bengal (India)

    2015-08-15

    In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein-Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge. Specific new charged stellar models are obtained where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We systematically analyze altogether the three sets of Solutions I, II, and III of the stellar models for a suitable functional relation of ν(r). However, it is observed that only the Solution I provides a physically valid and well-behaved situation, whereas the Solutions II and III are not well behaved and hence not included in the study. Thereafter it is exclusively shown that the Solution I can pass through several standard physical tests performed by us. To validate the solution set presented here a comparison has also been made with that of the compact stars, like RX J 1856 - 37, Her X - 1, PSR 1937+21, PSRJ 1614-2230, and PSRJ 0348+0432, and we have shown the feasibility of the models. (orig.)

  11. Setting and Achieving Objectives.

    Science.gov (United States)

    Knoop, Robert

    1986-01-01

    Provides basic guidelines which school officials and school boards may find helpful in negotiating, establishing, and managing objectives. Discusses characteristics of good objectives, specific and directional objectives, multiple objectives, participation in setting objectives, feedback on goal process and achievement, and managing a school…

  12. IN-SPIRALING CLUMPS IN BLUE COMPACT DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Elmegreen, Bruce G. [IBM Research Division, T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Zhang Hongxin; Hunter, Deidre A., E-mail: bge@watson.ibm.com [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)

    2012-03-10

    Giant star formation clumps in dwarf irregular galaxies can have masses exceeding a few percent of the galaxy mass enclosed inside their orbital radii. They can produce sufficient torques on dark matter halo particles, halo stars, and the surrounding disk to lose their angular momentum and spiral into the central region in 1 Gyr. Pairs of giant clumps with similarly large relative masses can interact and exchange angular momentum to the same degree. The result of this angular momentum loss is a growing central concentration of old stars, gas, and star formation that can produce a long-lived starburst in the inner region, identified with the blue compact dwarf (BCD) phase. This central concentration is proposed to be analogous to the bulge in a young spiral galaxy. Observations of star complexes in five local BCDs confirm the relatively large clump masses that are expected for this process. The observed clumps also seem to contain old field stars, even after background light subtraction, in which case the clumps may be long-lived. The two examples with clumps closest to the center have the largest relative clump masses and the greatest contributions from old stars. An additional indication that the dense central regions of BCDs are like bulges is the high ratio of the inner disk scale height to the scale length, which is comparable to 1 for four of the galaxies.

  13. 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.

  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. Code generation of RHIC accelerator device objects

    International Nuclear Information System (INIS)

    A RHIC Accelerator Device Object is an abstraction which provides a software view of a collection of collider control points known as parameters. A grammar has been defined which allows these parameters, along with code describing methods for acquiring and modifying them, to be specified efficiently in compact definition files. These definition files are processed to produce C++ source code. This source code is compiled to produce an object file which can be loaded into a front end computer. Each loaded object serves as an Accelerator Device Object class definition. The collider will be controlled by applications which set and get the parameters in instances of these classes using a suite of interface routines. Significant features of the grammar are described with details about the generated C++ code

  16. 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.

  17. 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

  18. Robust parameter estimation for compact binaries with ground-based gravitational-wave observations using LALInference

    CERN Document Server

    Veitch, John; Farr, Benjamin; Farr, Will M; Graff, Philip; Vitale, Salvatore; Aylott, Ben; Blackburn, Kent; Christensen, Nelson; Coughlin, Michael; Del Pozzo, Walter; Feroz, Farhan; Gair, Jonathan; Haster, Carl-Johan; Kalogera, Vicky; Littenberg, Tyson; Mandel, Ilya; O'Shaughnessy, Richard; Pitkin, Matthew; Rodriguez, Carl; Röver, Christian; Sidery, Trevor; Smith, Rory; Van Der Sluys, Marc; Vecchio, Alberto; Vousden, Will; Wade, Leslie

    2014-01-01

    The Advanced LIGO and Advanced Virgo gravitational wave (GW) detectors will begin operation in the coming years, with compact binary coalescence events a likely source for the first detections. The gravitational waveforms emitted directly encode information about the sources, including the masses and spins of the compact objects. Recovering the physical parameters of the sources from the GW observations is a key analysis task. This work describes the LALInference software library for Bayesian parameter estimation of compact binary coalescence (CBC) signals, which builds on several previous methods to provide a well-tested toolkit which has already been used for several studies. We are able to show using three independent sampling algorithms that our implementation consistently converges on the same results, giving confidence in the parameter estimates thus obtained. We demonstrate this with a detailed comparison on three compact binary systems: a binary neutron star, a neutron star-black hole binary and a bin...

  19. Compaction and sintering of nickel powder used encapsulation of irradiation targets

    International Nuclear Information System (INIS)

    The objective of this study was to develop an alternative way to produce targets for irradiation containing uranium, for the pair of 99Mo production 99mTc radionuclide. These targets were obtained by powder metallurgy, the compact serving as means for encapsulation a uranium cylinder to be irradiated. The targets were compacted in an axial hydraulic press applying different pressures up to 800 MPa. The sintering temperature was 600 °C in hydrogen atmosphere and it was used two sintering cycles, one for 4 h and the for 4 h plus 8 h time. The nickel powder was of high purity, that in order to provide the sealing of the fissile content within the compacted. The bulk density of compacted was evaluated by the method geometric. The porosity was measured by mercury porosimetry technique. The microstructure was investigated by optical microscopy. The results obtained with sintering powders involving confirm the feasibility of achieving a casing for uranium targets. (author)

  20. The progenitors of the compact early-type galaxies at high redshift

    International Nuclear Information System (INIS)

    We use GOODS and CANDELS images to identify progenitors of massive (M > 1010 M ☉) compact early-type galaxies (ETGs) at z ∼ 1.6. Because merging and accretion increase the size of the stellar component of galaxies, if the progenitors are among known star-forming galaxies, these must be compact themselves. We select candidate progenitors among compact Lyman-break galaxies at z ∼ 3 on the basis of their mass, star-formation rate (SFR), and central stellar density, and we find that these account for a large fraction of, and possibly all, compact ETGs at z ∼ 1.6. We find that the average far-UV spectral energy distribution (SED) of the candidates is redder than that of the non-candidates, but the optical and mid-IR SED are the same, implying that the redder UV of the candidates is inconsistent with larger dust obscuration and consistent with more evolved (aging) star formation. This is in line with other evidence suggesting that compactness is a sensitive predictor of passivity among high-redshift massive galaxies. We also find that the light distribution of both the compact ETGs and their candidate progenitors does not show any extended 'halos' surrounding the compact 'core,' both in individual images and in stacks. We argue that this is generally inconsistent with the morphology of merger remnants, even if gas rich, as predicted by N-body simulations. This suggests that the compact ETGs formed via highly dissipative, mostly gaseous accretion of units whose stellar components are very small and undetected in the Hubble Space Telescope images, with their stellar mass assembling in situ, and that they have not experienced any major merging until the epoch of observations at z ∼ 1.6.