WorldWideScience

Sample records for push probe holes

  1. Probing Black Hole Magnetic Fields with QED

    Directory of Open Access Journals (Sweden)

    Ilaria Caiazzo

    2018-05-01

    Full Text Available The effect of vacuum birefringence is one of the first predictions of quantum electrodynamics (QED: the presence of a charged Dirac field makes the vacuum birefringent when threaded by magnetic fields. This effect, extremely weak for terrestrial magnetic fields, becomes important for highly magnetized astrophysical objects, such as accreting black holes. In the X-ray regime, the polarization of photons traveling in the magnetosphere of a black hole is not frozen at emission but is changed by the local magnetic field. We show that, for photons traveling along the plane of the disk, where the field is expected to be partially organized, this results in a depolarization of the X-ray radiation. Because the amount of depolarization depends on the strength of the magnetic field, this effect can provide a way to probe the magnetic field in black-hole accretion disks and to study the role of magnetic fields in astrophysical accretion in general.

  2. Influence of access hole parameters on neutron moisture probe readings

    International Nuclear Information System (INIS)

    Abeele, W.V.

    1978-04-01

    Computing soil moisture content with a neutron probe requires use of a calibration curve that considers the thermal neutron capture cross section of the hole liner as well as the hole diameter. The influence of steel, polyvinyl chloride, and aluminum casings that fit 0.051 to 0.102-hole diameters was determined by comparison with neutron probe readings in uncased holes of corresponding diameters. Eccentricity of probe location was considered a potentially significant variable. The relationship between hole diameter and count rate also was investigated. The experiment was run in disturbed Bandelier tuff with an average dry density of 1.2 g . cm -3 and moisture content of 1.3 to 35.5% by volume. The casing material and hole diameter influenced the probe readings significantly, whereas eccentric location of the probe did not. Regression analyses showed an almost perfect inverse linear correlation between hole diameter and count rate

  3. Holographic probes of collapsing black holes

    International Nuclear Information System (INIS)

    Hubeny, Veronika E.; Maxfield, Henry

    2014-01-01

    We continue the programme of exploring the means of holographically decoding the geometry of spacetime inside a black hole using the gauge/gravity correspondence. To this end, we study the behaviour of certain extremal surfaces (focusing on those relevant for equal-time correlators and entanglement entropy in the dual CFT) in a dynamically evolving asymptotically AdS spacetime, specifically examining how deep such probes reach. To highlight the novel effects of putting the system far out of equilibrium and at finite volume, we consider spherically symmetric Vaidya-AdS, describing black hole formation by gravitational collapse of a null shell, which provides a convenient toy model of a quantum quench in the field theory. Extremal surfaces anchored on the boundary exhibit rather rich behaviour, whose features depend on dimension of both the spacetime and the surface, as well as on the anchoring region. The main common feature is that they reach inside the horizon even in the post-collapse part of the geometry. In 3-dimensional spacetime, we find that for sub-AdS-sized black holes, the entire spacetime is accessible by the restricted class of geodesics whereas in larger black holes a small region near the imploding shell cannot be reached by any boundary-anchored geodesic. In higher dimensions, the deepest reach is attained by geodesics which (despite being asymmetric) connect equal time and antipodal boundary points soon after the collapse; these can attain spacetime regions of arbitrarily high curvature and simultaneously have smallest length. Higher-dimensional surfaces can penetrate the horizon while anchored on the boundary at arbitrarily late times, but are bounded away from the singularity. We also study the details of length or area growth during thermalization. While the area of extremal surfaces increases monotonically, geodesic length is neither monotonic nor continuous

  4. Influence of access hole parameters on neutron moisture probe readings

    International Nuclear Information System (INIS)

    Abeele, W.V.

    1979-10-01

    Computing soil moisture content with a neutron probe requires use of a calibration curve that considers the thermal neutron capture cross section of the hole liner, as well as the hole diameter. The influence of steel, polyvinyl chloride, and aluminum casings that fit 0.051- to 0.102-m hole diameters was determined by comparison with neutron probe readings in uncased holes of corresponding diameters. Eccentricity of probe location was considered a potentially significant variable. The experiment was run in disturbed Bandelier tuff with an average dry density of 1.35g . cm -3 and moisture content of 3.8 to 26.7% by volume. The casing material and hole diameter influenced the probe readings significantly, whereas eccentric location of the probe did not. Regression analyses showed an almost perfect inverse linear correlation between hole diameter and count rate

  5. A novel calibration algorithm for five-hole pressure probe

    African Journals Online (AJOL)

    user

    Five-hole probes are used to measure the three components of velocity, inflow ... centre hole pressure labeled as 5. P and the off-axis holes labeled as 1. P , 2. P , 3 ..... of this study and is doing research in the flow control group of the institute.

  6. Femtosecond Pump-Push-Probe and Pump-Dump-Probe Spectroscopy of Conjugated Polymers: New Insight and Opportunities.

    Science.gov (United States)

    Kee, Tak W

    2014-09-18

    Conjugated polymers are an important class of soft materials that exhibit a wide range of applications. The excited states of conjugated polymers, often referred to as excitons, can either deactivate to yield the ground state or dissociate in the presence of an electron acceptor to form charge carriers. These interesting properties give rise to their luminescence and the photovoltaic effect. Femtosecond spectroscopy is a crucial tool for studying conjugated polymers. Recently, more elaborate experimental configurations utilizing three optical pulses, namely, pump-push-probe and pump-dump-probe, have been employed to investigate the properties of excitons and charge-transfer states of conjugated polymers. These studies have revealed new insight into femtosecond torsional relaxation and detrapping of bound charge pairs of conjugated polymers. This Perspective highlights (1) the recent achievements by several research groups in using pump-push-probe and pump-dump-probe spectroscopy to study conjugated polymers and (2) future opportunities and potential challenges of these techniques.

  7. Sample Preparation for Electron Probe Microanalysis—Pushing the Limits

    Science.gov (United States)

    Geller, Joseph D.; Engle, Paul D.

    2002-01-01

    There are two fundamental considerations in preparing samples for electron probe microanalysis (EPMA). The first one may seem obvious, but we often find it is overlooked. That is, the sample analyzed should be representative of the population from which it comes. The second is a direct result of the assumptions in the calculations used to convert x-ray intensity ratios, between the sample and standard, to concentrations. Samples originate from a wide range of sources. During their journey to being excited under the electron beam for the production of x rays there are many possibilities for sample alteration. Handling can contaminate samples by adding extraneous matter. In preparation, the various abrasives used in sizing the sample by sawing, grinding and polishing can embed themselves. The most accurate composition of a contaminated sample is, at best, not representative of the original sample; it is misleading. Our laboratory performs EPMA analysis on customer submitted samples and prepares over 250 different calibration standards including pure elements, compounds, alloys, glasses and minerals. This large variety of samples does not lend itself to mass production techniques, including automatic polishing. Our manual preparation techniques are designed individually for each sample. The use of automated preparation equipment does not lend itself to this environment, and is not included in this manuscript. The final step in quantitative electron probe microanalysis is the conversion of x-ray intensities ratios, known as the “k-ratios,” to composition (in mass fraction or atomic percent) and/or film thickness. Of the many assumptions made in the ZAF (where these letters stand for atomic number, absorption and fluorescence) corrections the localized geometry between the sample and electron beam, or takeoff angle, must be accurately known. Small angular errors can lead to significant errors in the final results. The sample preparation technique then becomes very

  8. Sample Preparation for Electron Probe Microanalysis-Pushing the Limits.

    Science.gov (United States)

    Geller, Joseph D; Engle, Paul D

    2002-01-01

    There are two fundamental considerations in preparing samples for electron probe microanalysis (EPMA). The first one may seem obvious, but we often find it is overlooked. That is, the sample analyzed should be representative of the population from which it comes. The second is a direct result of the assumptions in the calculations used to convert x-ray intensity ratios, between the sample and standard, to concentrations. Samples originate from a wide range of sources. During their journey to being excited under the electron beam for the production of x rays there are many possibilities for sample alteration. Handling can contaminate samples by adding extraneous matter. In preparation, the various abrasives used in sizing the sample by sawing, grinding and polishing can embed themselves. The most accurate composition of a contaminated sample is, at best, not representative of the original sample; it is misleading. Our laboratory performs EPMA analysis on customer submitted samples and prepares over 250 different calibration standards including pure elements, compounds, alloys, glasses and minerals. This large variety of samples does not lend itself to mass production techniques, including automatic polishing. Our manual preparation techniques are designed individually for each sample. The use of automated preparation equipment does not lend itself to this environment, and is not included in this manuscript. The final step in quantitative electron probe microanalysis is the conversion of x-ray intensities ratios, known as the "k-ratios," to composition (in mass fraction or atomic percent) and/or film thickness. Of the many assumptions made in the ZAF (where these letters stand for atomic number, absorption and fluorescence) corrections the localized geometry between the sample and electron beam, or takeoff angle, must be accurately known. Small angular errors can lead to significant errors in the final results. The sample preparation technique then becomes very

  9. Field evaluation of a direct push deployed sensor probe for vertical soil water content profiling

    Science.gov (United States)

    Vienken, Thomas; Reboulet, Ed; Leven, Carsten; Kreck, Manuel; Zschornack, Ludwig; Dietrich, Peter

    2015-04-01

    Reliable high-resolution information about vertical variations in soil water content, i.e. total porosity in the saturated zone, is essential for flow and transport predictions within the subsurface. However, porosity measurements are often associated with high efforts and high uncertainties, e.g. caused by soil disturbance during sampling or sensor installation procedures. In hydrogeological practice, commonly applied tools for the investigation of vertical soil water content distribution include gravimetric laboratory analyses of soil samples and neutron probe measurements. A yet less well established technique is the use of direct push-deployed sensor probes. Each of these methods is associated with inherent advantages and limitations due to their underlying measurement principles and operation modes. The presented study describes results of a joint field evaluation of the individual methods under different depositional and hydrogeological conditions with special focus on the performance on the direct push-deployed water content profiler. Therefore, direct push-profiling results from three different test sites are compared with results obtained from gravimetric analysis of soil cores and neutron probe measurements. In direct comparison, the applied direct push-based sensor probe proved to be a suitable alternative for vertical soil water content profiling to neutron probe technology, and, in addition, proved to be advantageous over gravimetric analysis in terms vertical resolution and time efficiency. Results of this study identify application-specific limitations of the methods and thereby highlight the need for careful data evaluation, even though neutron probe measurements and gravimetric analyses of soil samples are well established techniques (see Vienken et al. 2013). Reference: Vienken, T., Reboulet, E., Leven, C., Kreck, M., Zschornack, L., Dietrich, P., 2013. Field comparison of selected methods for vertical soil water content profiling. Journal of

  10. Probing strong-field general relativity near black holes

    CERN Multimedia

    CERN. Geneva; Alvarez-Gaumé, Luís

    2005-01-01

    Nature has sprinkled black holes of various sizes throughout the universe, from stellar mass black holes in X-ray sources to supermassive black holes of billions of solar masses in quasars. Astronomers today are probing the spacetime near black holes using X-rays, and gravitational waves will open a different view in the near future. These tools give us an unprecedented opportunity to test ultra-strong-field general relativity, including the fundamental theorem of the uniqueness of the Kerr metric and Roger Penrose's cosmic censorship conjecture. Already, fascinating studies of spectral lines are showing the extreme gravitational lensing effects near black holes and allowing crude measurements of black hole spin. When the ESA-NASA gravitational wave detector LISA begins its observations in about 10 years, it will make measurements of dynamical spacetimes near black holes with an accuracy greater even than that which theoreticians can reach with their computations today. Most importantly, when gravitational wa...

  11. Black holes are neither particle accelerators nor dark matter probes.

    Science.gov (United States)

    McWilliams, Sean T

    2013-01-04

    It has been suggested that maximally spinning black holes can serve as particle accelerators, reaching arbitrarily high center-of-mass energies. Despite several objections regarding the practical achievability of such high energies, and demonstrations past and present that such large energies could never reach a distant observer, interest in this problem has remained substantial. We show that, unfortunately, a maximally spinning black hole can never serve as a probe of high energy collisions, even in principle and despite the correctness of the original diverging energy calculation. Black holes can indeed facilitate dark matter annihilation, but the most energetic photons can carry little more than the rest energy of the dark matter particles to a distant observer, and those photons are actually generated relatively far from the black hole where relativistic effects are negligible. Therefore, any strong gravitational potential could probe dark matter equally well, and an appeal to black holes for facilitating such collisions is unnecessary.

  12. Pushed monocanalicular intubation versus probing as a primary management for congenital nasolacrimal obstruction

    Directory of Open Access Journals (Sweden)

    Elsawaby EA

    2016-09-01

    Full Text Available Emad Abdelaal Elsawaby, Rania Asem El Essawy, Sameh Hassan Abdelbaky, Yomna Magdy Ismail Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo, Egypt Purpose: Evaluation of efficiency, complications, and advantages of pushed monocanalicular intubation using Masterka® tube versus simple probing in patients with congenital nasolacrimal duct obstruction (CNLDO.Patients and methods: This is a case-controlled study that included 60 eyes (of 53 patients; 30 eyes underwent probing and 30 eyes intubation using the Masterka tube as a primary treatment for CNLDO. The children were aged between 6 months and 36 months at the time of surgery, with no previous nasolacrimal surgical procedure, and had one or more of the following clinical signs of nasolacrimal duct obstruction: epiphora, mucous discharge, and/or increased tear lake.Results: We defined success by absence of epiphora, mucous discharge, or increased tear lake 1 month after tube removal. The overall success rate in the probing group was 80%, while it was 83.3% in the intubation group.Conclusion: Pushed monocanalicular intubation is an effective method for treatment of CNLDO; it requires only mask inhalation anesthesia and could be considered as an appropriate alternative procedure with imperceptible complications. Keywords: epiphora, probing, intubation, monocanalicular, nasolacrimal

  13. Probe-Hole Field Emission Microscope System Controlled by Computer

    Science.gov (United States)

    Gong, Yunming; Zeng, Haishan

    1991-09-01

    A probe-hole field emission microscope system, controlled by an Apple II computer, has been developed and operated successfully for measuring the work function of a single crystal plane. The work functions on the clean W(100) and W(111) planes are measured to be 4.67 eV and 4.45 eV, respectively.

  14. The Oxford Probe: an open access five-hole probe for aerodynamic measurements

    Science.gov (United States)

    Hall, B. F.; Povey, T.

    2017-03-01

    The Oxford Probe is an open access five-hole probe designed for experimental aerodynamic measurements. The open access probe can be manufactured by the end user via additive manufacturing (metal or plastic). The probe geometry, drawings, calibration maps, and software are available under a creative commons license. The purpose is to widen access to aerodynamic measurement techniques in education and research environments. There are many situations in which the open access probe will allow results of comparable accuracy to a well-calibrated commercial probe. We discuss the applications and limitations of the probe, and compare the calibration maps for 16 probes manufactured in different materials and at different scales, but with the same geometrical design.

  15. The Oxford Probe: an open access five-hole probe for aerodynamic measurements

    International Nuclear Information System (INIS)

    Hall, B F; Povey, T

    2017-01-01

    The Oxford Probe is an open access five-hole probe designed for experimental aerodynamic measurements. The open access probe can be manufactured by the end user via additive manufacturing (metal or plastic). The probe geometry, drawings, calibration maps, and software are available under a creative commons license. The purpose is to widen access to aerodynamic measurement techniques in education and research environments. There are many situations in which the open access probe will allow results of comparable accuracy to a well-calibrated commercial probe. We discuss the applications and limitations of the probe, and compare the calibration maps for 16 probes manufactured in different materials and at different scales, but with the same geometrical design. (paper)

  16. Automorphic black holes as probes of extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Cassella, Kayleigh, E-mail: kcassell@berkeley.edu [Department of Physics, Indiana University South Bend, 1700 Mishawaka Ave., South Bend, IN 46634 (United States); Schimmrigk, Rolf, E-mail: netahu@yahoo.com [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)

    2012-05-11

    Recent progress in the understanding of the statistical nature of black hole entropy shows that the counting functions in certain classes of models are determined by automorphic forms of higher rank. In this paper we combine these results with Langlands' reciprocity conjecture to view black holes as probes of the geometry of spacetime. This point of view can be applied in any framework leading to automorphic forms, independently of the degree of supersymmetry of the models. In the present work we focus on the class of Chaudhuri-Hockney-Lykken compactifications defined as quotients associated to Z{sub N} groups. We show that the black hole entropy of these CHL{sub N} models can be derived from elliptic motives, thereby providing the simplest possible geometric building blocks of the Siegel type entropy count.

  17. Probing Primordial Black Hole Dark Matter with Gravitational Waves.

    Science.gov (United States)

    Kovetz, Ely D

    2017-09-29

    Primordial black holes (PBHs) have long been suggested as a candidate for making up some or all of the dark matter in the Universe. Most of the theoretically possible mass range for PBH dark matter has been ruled out with various null observations of expected signatures of their interaction with standard astrophysical objects. However, current constraints are significantly less robust in the 20  M_{⊙}≲M_{PBH}≲100  M_{⊙} mass window, which has received much attention recently, following the detection of merging black holes with estimated masses of ∼30  M_{⊙} by LIGO and the suggestion that these could be black holes formed in the early Universe. We consider the potential of advanced LIGO (aLIGO) operating at design sensitivity to probe this mass range by looking for peaks in the mass spectrum of detected events. To quantify the background, which is due to black holes that are formed from dying stars, we model the shape of the stellar-black-hole mass function and calibrate its amplitude to match the O1 results. Adopting very conservative assumptions about the PBH and stellar-black-hole merger rates, we show that ∼5  yr of aLIGO data can be used to detect a contribution of >20  M_{⊙} PBHs to dark matter down to f_{PBH}99.9% confidence level. Combined with other probes that already suggest tension with f_{PBH}=1, the obtainable independent limits from aLIGO will thus enable a firm test of the scenario that PBHs make up all of dark matter.

  18. Probing near extremal black holes with D-branes

    International Nuclear Information System (INIS)

    Maldacena, J.

    1998-01-01

    We calculate the one loop effective action for D-brane probes moving in the presence of near Bogomol close-quote nyi-Prasad-Sommerfield D-branes. The v 2 term agrees with supergravity in all cases and the static force agrees for a five-dimensional black hole with two large charges. It also agrees qualitatively in all the other cases. We make some comments on the M(atrix) theory interpretation of these results. copyright 1998 The American Physical Society

  19. Ultrafast probing of core hole localization in N2.

    Science.gov (United States)

    Schöffler, M S; Titze, J; Petridis, N; Jahnke, T; Cole, K; Schmidt, L Ph H; Czasch, A; Akoury, D; Jagutzki, O; Williams, J B; Cherepkov, N A; Semenov, S K; McCurdy, C W; Rescigno, T N; Cocke, C L; Osipov, T; Lee, S; Prior, M H; Belkacem, A; Landers, A L; Schmidt-Böcking, H; Weber, Th; Dörner, R

    2008-05-16

    Although valence electrons are clearly delocalized in molecular bonding frameworks, chemists and physicists have long debated the question of whether the core vacancy created in a homonuclear diatomic molecule by absorption of a single x-ray photon is localized on one atom or delocalized over both. We have been able to clarify this question with an experiment that uses Auger electron angular emission patterns from molecular nitrogen after inner-shell ionization as an ultrafast probe of hole localization. The experiment, along with the accompanying theory, shows that observation of symmetry breaking (localization) or preservation (delocalization) depends on how the quantum entangled Bell state created by Auger decay is detected by the measurement.

  20. The black hole symphony: probing new physics using gravitational waves.

    Science.gov (United States)

    Gair, Jonathan R

    2008-12-13

    The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.

  1. Development of hole inspection program using touch trigger probe on CNC machine tools

    International Nuclear Information System (INIS)

    Lee, Chan Ho; Lee, Eung Suk

    2012-01-01

    According to many customers' requests, optical measurement module (OMM) applications using automatic measuring devices to measure the machined part rapidly on a machine tool have increased steeply. Touch trigger probes are being used for job setup and feature inspection as automatic measuring devices, and this makes quality checking and machining compensation possible. Therefore, in this study, the use of touch trigger probes for accurate measurement of the machined part has been studied and a macro program for a hole measuring cycle has been developed. This hole is the most common feature to be measured, but conventional methods are still not free from measuring error. In addition, the eccentricity change of the least square circle was simulated according to the roundness error in a hole measurement. To evaluate the reliability of this study, the developed hole measuring program was executed to measure the hole plate on the machine and verify the roundness error in the eccentricity simulation result

  2. Probing loop quantum gravity with evaporating black holes.

    Science.gov (United States)

    Barrau, A; Cailleteau, T; Cao, X; Diaz-Polo, J; Grain, J

    2011-12-16

    This Letter aims at showing that the observation of evaporating black holes should allow the usual Hawking behavior to be distinguished from loop quantum gravity (LQG) expectations. We present a full Monte Carlo simulation of the evaporation in LQG and statistical tests that discriminate between competing models. We conclude that contrarily to what was commonly thought, the discreteness of the area in LQG leads to characteristic features that qualify evaporating black holes as objects that could reveal quantum gravity footprints. © 2011 American Physical Society

  3. A Miniature Four-Hole Probe for Measurement of Three-Dimensional Flow with Large Gradients

    Directory of Open Access Journals (Sweden)

    Ravirai Jangir

    2014-01-01

    Full Text Available A miniature four-hole probe with a sensing area of 1.284 mm2 to minimise the measurement errors due to the large pressure and velocity gradients that occur in highly three-dimensional turbomachinery flows is designed, fabricated, calibrated, and validated. The probe has good spatial resolution in two directions, thus minimising spatial and flow gradient errors. The probe is calibrated in an open jet calibration tunnel at a velocity of 50 m/s in yaw and pitch angles range of ±40 degrees with an interval of 5 degrees. The calibration coefficients are defined, determined, and presented. Sensitivity coefficients are also calculated and presented. A lookup table method is used to determine the four unknown quantities, namely, total and static pressures and flow angles. The maximum absolute errors in yaw and pitch angles are 2.4 and 1.3 deg., respectively. The maximum absolute errors in total, static, and dynamic pressures are 3.4, 3.9, and 4.9% of the dynamic pressures, respectively. Measurements made with this probe, a conventional five-hole probe and a miniature Pitot probe across a calibration section, demonstrated that the errors due to gradient and surface proximity for this probe are considerably reduced compared to the five-hole probe.

  4. Results of the non-nulling calibration of five-hole pressure probe

    Science.gov (United States)

    Bereznai, J.; Mlynár, P.; Masaryk, M.

    2017-09-01

    In the laboratory of the Institute of Energy Machinery, Faculty of Mechanical Engineering in Bratislava were produced amount of pressure probes of different designs. Special position among themselves are five-hole pressure probe with tip of sphere or wedge used to determine the velocity vector in a unknown flow fields. Such probes have to be calibrated during blowing an air stream of known velocity magnitude and components of the velocity vector at different angles of attack, when the characteristic information about pressures on a sensitive part of the measuring probe is obtained.

  5. Measurement of Air Flow Characteristics Using Seven-Hole Cone Probes

    Science.gov (United States)

    Takahashi, Timothy T.

    1997-01-01

    The motivation for this work has been the development of a wake survey system. A seven-hole probe can measure the distribution of static pressure, total pressure, and flow angularity in a wind tunnel environment. The author describes the development of a simple, very efficient algorithm to compute flow properties from probe tip pressures. Its accuracy and applicability to unsteady, turbulent flow are discussed.

  6. Gravitational-wave localization alone can probe origin of stellar-mass black hole mergers.

    Science.gov (United States)

    Bartos, I; Haiman, Z; Marka, Z; Metzger, B D; Stone, N C; Marka, S

    2017-10-10

    The recent discovery of gravitational waves from stellar-mass binary black hole mergers by the Laser Interferometer Gravitational-wave Observatory opened the door to alternative probes of stellar and galactic evolution, cosmology and fundamental physics. Probing the origin of binary black hole mergers will be difficult due to the expected lack of electromagnetic emission and limited localization accuracy. Associations with rare host galaxy types-such as active galactic nuclei-can nevertheless be identified statistically through spatial correlation. Here we establish the feasibility of statistically proving the connection between binary black hole mergers and active galactic nuclei as hosts, even if only a sub-population of mergers originate from active galactic nuclei. Our results are the demonstration that the limited localization of gravitational waves, previously written off as not useful to distinguish progenitor channels, can in fact contribute key information, broadening the range of astrophysical questions probed by binary black hole observations.Binary black hole mergers have recently been observed through the detection of gravitational wave signatures. The authors demonstrate that their association with active galactic nuclei can be made through a statistical spatial correlation.

  7. Does the black hole shadow probe the event horizon geometry?

    Science.gov (United States)

    Cunha, Pedro V. P.; Herdeiro, Carlos A. R.; Rodriguez, Maria J.

    2018-04-01

    There is an exciting prospect of obtaining the shadow of astrophysical black holes (BHs) in the near future with the Event Horizon Telescope. As a matter of principle, this justifies asking how much one can learn about the BH horizon itself from such a measurement. Since the shadow is determined by a set of special photon orbits, rather than horizon properties, it is possible that different horizon geometries yield similar shadows. One may then ask how sensitive is the shadow to details of the horizon geometry? As a case study, we consider the double Schwarzschild BH and analyze the impact on the lensing and shadows of the conical singularity that holds the two BHs in equilibrium—herein taken to be a strut along the symmetry axis in between the two BHs. Whereas the conical singularity induces a discontinuity of the scattering angle of photons, clearly visible in the lensing patterns along the direction of the strut's location, it produces no observable effect on the shadows, whose edges remain everywhere smooth. The latter feature is illustrated by examples including both equal and unequal mass BHs. This smoothness contrasts with the intrinsic geometry of the (spatial sections of the) horizon of these BHs, which is not smooth, and provides a sharp example on how BH shadows are insensitive to some horizon geometry details. This observation, moreover, suggests that for the study of their shadows, this static double BH system may be an informative proxy for a dynamical binary.

  8. Direct calibration framework of triple-hole pressure probes for incompressible flow

    International Nuclear Information System (INIS)

    Díaz, K M Argüelles; Oro, J M Fernández; Marigorta, E Blanco

    2008-01-01

    This paper carries out a mathematical analysis of the limits and data reduction techniques of three-hole pressure (THP) probes operating in a 'non-nulling' mode for incompressible flow. As a result of this analysis, a direct procedure is advanced, based on the distinction of several zones within the angular range, where different relations can be applied to obtain the flow variables. This proposal provides a considerable increment of the operative angular range of THP probes: about ±70° instead of the typical ±35° for a cylindrical probe. This may extend the application of these probes in highly unsteady flows, or reduce the acquisition and data reduction effort minimizing the necessity of probe reorientation. The influence of the data reduction technique on the uncertainty transmission is also presented in the paper. From detailed considerations, it is demonstrated that the results uncertainty depends on the specific probe, but it is unaffected by the mathematical procedure employed to calculate the flow variables. Validation measurements with pneumatic probes have been made for Reynolds numbers from 4 × 10 3 to 3.5 × 10 4 . In addition, a highly unsteady measurement in a low-speed axial flow fan is succinctly analysed. Taking into account both attainable angular range and uncertainty, it is determined that the optimal construction angle for the holes of a low frequency response THP probe lies between 30° and 60°, while for fast response probes, in order to avoid the separated flow region, the optimal construction angle is around 30°

  9. Probing the singlet character of the two-hole states in cuprate superconductors

    NARCIS (Netherlands)

    Ghiringhelli, G; Brookes, NB; Tjeng, LH; Mizokawa, T; Tjernberg, O; Menovsky, AA; Steeneken, P.G.

    Using spin-resolved resonant photoemission we have probed the singlet vs. triplet character of the two-hole state in the layered cuprates Bi2Sr2CaCu2O8+delta La2-xSrxCuO4 and Sr2CuO2Cl2. The combination of the photon circular polarization with the photoelectron spin detection gives access to the

  10. LISA extreme-mass-ratio inspiral events as probes of the black hole mass function

    International Nuclear Information System (INIS)

    Gair, Jonathan R.; Tang, Christopher; Volonteri, Marta

    2010-01-01

    One of the sources of gravitational waves for the proposed space-based gravitational wave detector, the Laser Interferometer Space Antenna (LISA), are the inspirals of compact objects into supermassive black holes in the centers of galaxies--extreme-mass-ratio inspirals (EMRIs). Using LISA observations, we will be able to measure the parameters of each EMRI system detected to very high precision. However, the statistics of the set of EMRI events observed by LISA will be more important in constraining astrophysical models than extremely precise measurements for individual systems. The black holes to which LISA is most sensitive are in a mass range that is difficult to probe using other techniques, so LISA provides an almost unique window onto these objects. In this paper we explore, using Bayesian techniques, the constraints that LISA EMRI observations can place on the mass function of black holes at low redshift. We describe a general framework for approaching inference of this type--using multiple observations in combination to constrain a parametrized source population. Assuming that the scaling of the EMRI rate with the black-hole mass is known and taking a black-hole distribution given by a simple power law, dn/dlnM=A 0 (M/M * ) α 0 , we find that LISA could measure the parameters to a precision of Δ(lnA 0 )∼0.08, and Δ(α 0 )∼0.03 for a reference model that predicts ∼1000 events. Even with as few as 10 events, LISA should constrain the slope to a precision ∼0.3, which is the current level of observational uncertainty in the low-mass slope of the black-hole mass function. We also consider a model in which A 0 and α 0 evolve with redshift, but find that EMRI observations alone do not have much power to probe such an evolution.

  11. Five-hole pitot probe measurements of swirl, confinement and nozzle effects on confined turbulent flow

    Science.gov (United States)

    Lilley, D. G.; Scharrer, G. L.

    1984-01-01

    The results of a time-mean flow characterization of nonswirling and swirling inert flows in a combustor are reported. The five-hole pitot probe technique was used in axisymmetric test sections with expansion ratios of 1 and 1.5. A prominent corner recirculation zone identified in nonswirling expanding flows decreased in size with swirling flows. The presence of a downstream nozzle led to an adverse pressure gradient at the wall and a favorable gradient near the centerline. Reducing the expansion ratio reduced the central recirculation length. No significant effect was introduced in the flowfield by a gradual expansion.

  12. Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn; Chi, Li-Feng, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn; Wang, Sui-Dong, E-mail: wangsd@suda.edu.cn, E-mail: chilf@suda.edu.cn, E-mail: bdong@suda.edu.cn [Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123 (China)

    2015-03-23

    Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process.

  13. Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

    International Nuclear Information System (INIS)

    Cui, Ze-Qun; Wang, Shun; Chen, Jian-Mei; Gao, Xu; Dong, Bin; Chi, Li-Feng; Wang, Sui-Dong

    2015-01-01

    Electron and hole trapping into the nano-floating-gate of a pentacene-based organic field-effect transistor nonvolatile memory is directly probed by Kelvin probe force microscopy. The probing is straightforward and non-destructive. The measured surface potential change can quantitatively profile the charge trapping, and the surface characterization results are in good accord with the corresponding device behavior. Both electrons and holes can be trapped into the nano-floating-gate, with a preference of electron trapping than hole trapping. The trapped charge quantity has an approximately linear relation with the programming/erasing gate bias, indicating that the charge trapping in the device is a field-controlled process

  14. Charged Lifshitz black hole and probed Lorentz-violation fermions from holography

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Cheng-Jian, E-mail: rocengeng@hotmail.com [Department of Physics, Nanchang University, Nanchang, 330031 (China); Center for Relativistic Astrophysics and High Energy Physics, Nanchang University, Nanchang 330031 (China); Kuang, Xiao-Mei, E-mail: xmeikuang@gmail.com [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile); Shu, Fu-Wen, E-mail: shufuwen@ncu.edu.cn [Department of Physics, Nanchang University, Nanchang, 330031 (China); Center for Relativistic Astrophysics and High Energy Physics, Nanchang University, Nanchang 330031 (China)

    2017-06-10

    We analytically obtain a new charged Lifshitz solution by adding a non-relativistic Maxwell field in Hořava–Lifshitz gravity. The black hole exhibits an anisotropic scaling between space and time (Lifshitz scaling) in the UV limit, while in the IR limit, the Lorentz invariance is approximately recovered. We introduce the probed Lorentz-violation fermions into the background and holographically investigate the spectral properties of the dual fermionic operator. The Lorentz-violation of the fermions will enhance the peak and correspond larger fermi momentum, which compensates the non-relativistic bulk effect of the dynamical exponent (z). For a fixed z, when the Lorentz-violation of fermions increases to a critical value, the behavior of the low energy excitation goes from a non-Fermi liquid type to a Fermi liquid type, which implies a kind of phase transition.

  15. Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol–cloud interactions

    Directory of Open Access Journals (Sweden)

    R. Calmer

    2018-05-01

    Full Text Available The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA. In atmospheric research, lightweight RPAs ( <  2.5 kg are now able to accurately measure atmospheric wind vectors, even in a cloud, which provides essential observing tools for understanding aerosol–cloud interactions. The European project BACCHUS (impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding focuses on these specific interactions. In particular, vertical wind velocity at cloud base is a key parameter for studying aerosol–cloud interactions. To measure the three components of wind, a RPA is equipped with a five-hole probe, pressure sensors, and an inertial navigation system (INS. The five-hole probe is calibrated on a multi-axis platform, and the probe–INS system is validated in a wind tunnel. Once mounted on a RPA, power spectral density (PSD functions and turbulent kinetic energy (TKE derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland, a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological

  16. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Joao Eduardo [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, Department of Mechanical Engineering, Lisbon (Portugal); Pereira, Nuno H.C. [EST Setubal, Polytechnic Institute of Setubal, Department of Mechanical Engineering, Setubal (Portugal); Matos, Jorge [Instituto Superior Tecnico, Technical University of Lisbon, Department of Civil Engineering and Architecture, Lisbon (Portugal); Frizell, Kathleen H. [U.S. Bureau of Reclamation, Denver, CO (United States)

    2010-01-15

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows. (orig.)

  17. Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in air-water flows

    Science.gov (United States)

    Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.

    2010-01-01

    The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex air-water flows, is described in this paper. The air-water flows envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-Flow turbines), where the flow direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the flow measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-Flow turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex air-water flows.

  18. Prospects for Probing Strong Gravity with a Pulsar-Black Hole System

    Science.gov (United States)

    Wex, N.; Liu, K.; Eatough, R. P.; Kramer, M.; Cordes, J. M.; Lazio, T. J. W.

    2012-01-01

    The discovery of a pulsar (PSR) in orbit around a black hole (BH) is expected to provide a superb new probe of relativistic gravity and BH properties. Apart from a precise mass measurement for the BH, one could expect a clean verification of the dragging of space-time caused by the BH spin. In order to measure the quadrupole moment of the BH for testing the no-hair theorem of general relativity (GR), one has to hope for a sufficiently massive BH. In this respect, a PSR orbiting the super-massive BH in the center of our Galaxy would be the ultimate laboratory for gravity tests with PSRs. But even for gravity theories that predict the same properties for BHs as GR, a PSR-BH system would constitute an excellent test system, due to the high grade of asymmetry in the strong field properties of these two components. Here we highlight some of the potential gravity tests that one could expect from different PSR-BH systems.

  19. Five-hole pitot probe time-mean velocity measurements in confined swirling flows

    Science.gov (United States)

    Yoon, H. K.; Lilley, D. G.

    1983-01-01

    Nonswirling and swirling nonreacting flows in an axisymmetric test section with an expansion ratio D/d = 2, which may be equipped with contraction nozzles of area ratios 2 and 4, are investigated. The effects of a number of geometric parameters on the flow-field are investigated, among them side-wall expansion angles of 90 and 45 deg, swirl vane angles of 0, 38, 45, 60, and 70 deg, and contraction nozzle locations L/D = 1 and 2 (if present). Data are acquired by means of a five-hole pitot probe enabling three time-mean velocity components in the axial, radial, and azimuthal directions to be measured. The velocities are extensively plotted and artistic impressions of recirculation zones are set forth. The presence of a swirler is found to shorten the corner recirculation zone and to generate a central recirculation zone followed by a precessing vortex core. A gradual inlet expansion has the effect of encouraging the flow to remain close to the sidewall and shortening the extent of the corner recirculation zone in all cases investigated.

  20. Probing gravitational parity violation with gravitational waves from stellar-mass black hole binaries

    Science.gov (United States)

    Yagi, Kent; Yang, Huan

    2018-05-01

    The recent discovery of gravitational-wave events has offered us unique test beds of gravity in the strong and dynamical field regime. One possible modification to General Relativity is the gravitational parity violation that arises naturally from quantum gravity. Such parity violation gives rise to the so-called amplitude birefringence in gravitational waves, in which one of the circularly polarized modes is amplified while the other one is suppressed during their propagation. In this paper, we study how well one can measure gravitational parity violation via the amplitude birefringence effect of gravitational waves sourced by stellar-mass black hole binaries. We choose Chern-Simons gravity as an example and work within an effective field theory formalism to ensure that the approximate theory is well posed. We consider gravitational waves from both individual sources and stochastic gravitational-wave backgrounds. Regarding bounds from individual sources, we estimate such bounds using a Fisher analysis and carry out Monte Carlo simulations by randomly distributing sources over their sky location and binary orientation. We find that the bounds on the scalar field evolution in Chern-Simons gravity from the recently discovered gravitational-wave events are too weak to satisfy the weak Chern-Simons approximation, while aLIGO with its design sensitivity can place meaningful bounds. Regarding bounds from stochastic gravitational-wave backgrounds, we set the threshold signal-to-noise ratio for detection of the parity-violation mode as 5 and estimate projected bounds with future detectors assuming that signals are consistent with no parity violation. In an ideal situation in which all the source parameters and binary black hole merger-rate history are known a priori, we find that a network of two third-generation detectors is able to place bounds that are comparable to or slightly stronger than binary pulsar bounds. In a more realistic situation in which one does not have

  1. Vertical wind velocity measurements using a five-hole probe with remotely piloted aircraft to study aerosol-cloud interactions

    Science.gov (United States)

    Calmer, Radiance; Roberts, Gregory C.; Preissler, Jana; Sanchez, Kevin J.; Derrien, Solène; O'Dowd, Colin

    2018-05-01

    The importance of vertical wind velocities (in particular positive vertical wind velocities or updrafts) in atmospheric science has motivated the need to deploy multi-hole probes developed for manned aircraft in small remotely piloted aircraft (RPA). In atmospheric research, lightweight RPAs ( power spectral density (PSD) functions and turbulent kinetic energy (TKE) derived from the five-hole probe are compared with sonic anemometers on a meteorological mast. During a BACCHUS field campaign at Mace Head Atmospheric Research Station (Ireland), a fleet of RPAs was deployed to profile the atmosphere and complement ground-based and satellite observations of physical and chemical properties of aerosols, clouds, and meteorological state parameters. The five-hole probe was flown on straight-and-level legs to measure vertical wind velocities within clouds. The vertical velocity measurements from the RPA are validated with vertical velocities derived from a ground-based cloud radar by showing that both measurements yield model-simulated cloud droplet number concentrations within 10 %. The updraft velocity distributions illustrate distinct relationships between vertical cloud fields in different meteorological conditions.

  2. Use of interfacial layers to prolong hole lifetimes in hematite probed by ultrafast transient absorption spectroscopy

    Science.gov (United States)

    Paradzah, Alexander T.; Diale, Mmantsae; Maabong, Kelebogile; Krüger, Tjaart P. J.

    2018-04-01

    Hematite is a widely investigated material for applications in solar water oxidation due primarily to its small bandgap. However, full realization of the material continues to be hampered by fast electron-hole recombination rates among other weaknesses such as low hole mobility, short hole diffusion length and low conductivity. To address the problem of fast electron-hole recombination, researchers have resorted to growth of nano-structured hematite, doping and use of under-layers. Under-layer materials enhance the photo-current by minimising electron-hole recombination through suppressing of back electron flow from the substrate, such as fluorine-doped tin oxide (FTO), to hematite. We have carried out ultrafast transient absorption spectroscopy on hematite in which Nb2O5 and SnO2 materials were used as interfacial layers to enhance hole lifetimes. The transient absorption data was fit with four different lifetimes ranging from a few hundred femtoseconds to a few nanoseconds. We show that the electron-hole recombination is slower in samples where interfacial layers are used than in pristine hematite. We also develop a model through target analysis to illustrate the effect of under-layers on electron-hole recombination rates in hematite thin films.

  3. Event Horizon Telescope observations as probes for quantum structure of astrophysical black holes

    Science.gov (United States)

    Giddings, Steven B.; Psaltis, Dimitrios

    2018-04-01

    The need for a consistent quantum evolution for black holes has led to proposals that their semiclassical description is modified not just near the singularity, but at horizon or larger scales. If such modifications extend beyond the horizon, they influence regions accessible to distant observation. Natural candidates for these modifications behave like metric fluctuations, with characteristic length scales and timescales set by the horizon radius. We investigate the possibility of using the Event Horizon Telescope to observe these effects, if they have a strength sufficient to make quantum evolution consistent with unitarity, without introducing new scales. We find that such quantum fluctuations can introduce a strong time dependence for the shape and size of the shadow that a black hole casts on its surrounding emission. For the black hole in the center of the Milky Way, detecting the rapid time variability of its shadow will require nonimaging timing techniques. However, for the much larger black hole in the center of the M87 galaxy, a variable black-hole shadow, if present with these parameters, would be readily observable in the individual snapshots that will be obtained by the Event Horizon Telescope.

  4. Phase structure of the Born-Infeld-anti-de Sitter black holes probed by non-local observables

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Xiao-Xiong [Chongqing Jiaotong University, School of Material Science and Engineering, Chongqing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, Beijing (China); Liu, Xian-Ming [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA (United States); Hubei University for Nationalities, Center for Theoretical Physics, School of Sciences, Enshi, Hubei (China); Li, Li-Fang [Chinese Academy of Sciences, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Beijing (China)

    2016-11-15

    With the non-local observables such as two point correlation function and holographic entanglement entropy, we probe the phase structure of the Born-Infeld-anti-de Sitter black holes. For the case bQ > 0.5, where b is the Born-Infeld parameter and Q is the charge of the black hole, the phase structure is found to be similar to that of the Van der Waals phase transition, namely the black hole undergoes a first order phase transition and a second order phase transition before it reaches a stable phase. While for the case bQ < 0.5, a new phase branch emerges besides the Van der Waals phase transition. For the first order phase transition, the equal area law is checked, and for the second order phase transition, the critical exponent of the heat capacity is obtained. All these results are found to be the same as that observed in the entropy-temperature plane. (orig.)

  5. Characterization of Vadose Zone Sediments Below the TX Tank Farm: Probe Holes C3830, C3831, C3832 and 299-W10-27

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R JEFFREY.; Bjornstad, Bruce N.; Horton, Duane G.; Lanigan, David C.; Lindenmeier, Clark W.; Lindberg, Michael J.; Clayton, Ray E.; LeGore, Virginia L.; Orr, Robert D.; Kutnyakov, Igor V.; Baum, Steven R.; Geiszler, Keith N.; Valenta, Michelle M.; Vickerman, Tanya S.

    2004-04-01

    Pacific Northwest National Laboratory performed detailed analyses on vadose zone sediments from within Waste Management Area T-TX-TY. This report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from three probe holes (C3830, C3831, and C3832) in the TX Tank Farm, and from borehole 299-W-10-27. Sediments from borehole 299-W-10-27 are considered to be uncontaminated sediments that can be compared with contaminated sediments. This report also presents our interpretation of the sediment lithologies, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater below the TX Tank Farm. Sediment from the probe holes was analyzed for: moisture, radionuclide and carbon contents;, one-to-one water extracts (soil pH, electrical conductivity, cation, trace metal, and anion data), and 8 M nitric acid extracts. Overall, our analyses showed that common ion exchange is a key mechanism that influences the distribution of contaminants within that portion of the vadose zone affected by tank liquor. We did not observe significant indications of caustic alteration of the sediment mineralogy or porosity, or significant zones of slightly elevated pH values in the probe holes. The sediments do show that sodium-, nitrate-, and sulfate-dominated fluids are present. The fluids are more dilute than tank fluids observed below tanks at the SX and BX Tank Farms. Three primary stratigraphic units were encountered in each probe hole: (1) backfill material, (2) the Hanford formation, and (3) the Cold Creek unit. Each of the probe holes contain thin fine-grained layers in the Hanford H2 stratigraphic unit that may impact the flow of leaked fluids and effect irregular and horizontal flow. The probe holes could not penetrate below the enriched calcium carbonate strata of the Cold Creek lower subunit; therefore, we did not

  6. Probing the Accretion Geometry of Black Holes with X-Ray Polarization

    Science.gov (United States)

    Schnitman, Jeremy D.

    2011-01-01

    In the coming years, new space missions will be able to measure X-ray polarization at levels of 1% or better in the approx.1-10 keV energy band. In particular, X-ray polarization is an ideal tool for determining the nature of black hole (BH) accretion disks surrounded by hot coronae. Using a Monte Carlo radiation transport code in full general relativity, we calculate the spectra and polarization features of these BH systems. At low energies, the signal is dominated by the thermal flux coming directly from the optically thick disk. At higher energies, the thermal seed photons have been inverse-Compton scattered by the corona, often reflecting back off the disk before reaching the observer, giving a distinctive polarization signature. By measuring the degree and angle of this X-ray polarization, we can infer the BH inclination, the emission geometry of the accretion flow, and also determine the spin of the black hole.

  7. Direct probe of the inner accretion flow around the supermassive black hole in NGC 2617

    Czech Academy of Sciences Publication Activity Database

    Giustini, M.; Costantini, E.; De Marco, B.; Svoboda, Jiří; Motta, S. E.; Proga, D.; Saxton, R.; Ferrigno, C.; Longinotti, A. L.; Miniutti, G.; Grupe, D.; Mathur, S.; Shappee, B. J.; Prieto, J. L.; Stanek, K.

    2017-01-01

    Roč. 597, January (2017), A66/1-A66/13 E-ISSN 1432-0746 R&D Projects: GA ČR(CZ) GP14-20970P; GA MŠk(CZ) LH14049 Institutional support: RVO:67985815 Keywords : black hole physics * observational methods * active galaxies Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.014, year: 2016

  8. DOUBLE QUASARS: PROBES OF BLACK HOLE SCALING RELATIONSHIPS AND MERGER SCENARIOS

    International Nuclear Information System (INIS)

    Foreman, G.; Volonteri, M.; Dotti, M.

    2009-01-01

    We analyze the available sample of double quasars, and investigate their physical properties. Our sample comprises 85 pairs, selected from the Sloan Digital Sky Survey (SDSS). We derive physical parameters for the engine and the host, and model the dynamical evolution of the pair. First, we compare different scaling relationships between massive black holes and their hosts (bulge mass, velocity dispersion, and their possible redshift dependences), and discuss their consistency. We then compute dynamical friction timescales for the double quasar systems to investigate their frequency and their agreement with the m erger drivenscenario for quasar triggering. In optical surveys, such as the SDSS, N double,qso /N qso ∼ 0.1%. Comparing typical merging timescales to expected quasar lifetimes, the fraction of double quasars should be roughly a factor of 10 larger than observed. Additionally, we find that, depending on the correlations between black holes and their hosts, the occurrence of double quasars could be redshift dependent. Comparison of our models to the SDSS quasar catalog suggests that double quasars should be more common at high redshift. We compare the typical separations at which double quasars are observed to the predictions of merger simulations. We find that the distribution of physical separations peaks at ∼30 kpc, with a tail at larger separations (∼100-200 kpc). The peak of the distribution is roughly consistent with the first episode of quasar activity found in equal mass mergers simulations. The tail of the quasar pairs distribution at large separations is instead inconsistent with any quasar activity predicted by published simulations. These large separation pairs are instead consistent with unequal mass mergers where gas is dynamically perturbed during the first pericentric passage, but the gas reaches the black hole only at the next apocenter, where the pair is observed.

  9. Enhanced performance of fast-response 3-hole wedge probes for transonic flows in axial turbomachinery

    Energy Technology Data Exchange (ETDEWEB)

    Delhaye, D.; Paniagua, G. [von Karman Institute for Fluid Dynamics, Turbomachinery and Propulsion Department, Rhode-Saint-Genese (Belgium); Fernandez Oro, J.M. [Universidad de Oviedo, Area de Mecanica de Fluidos, Gijon (Spain); Denos, R. [European Commission, Directorate General for Research, Brussels (Belgium)

    2011-01-15

    The paper presents the development and application of a three-sensor wedge probe to measure unsteady aerodynamics in a transonic turbine. CFD has been used to perform a detailed uncertainty analysis related to probe-induced perturbations, in particular the separation zones appearing on the wedge apex. The effects of the Reynolds and Mach numbers are studied using both experimental data together with CFD simulations. The angular range of the probe and linearity of the calibration maps are enhanced with a novel zonal calibration technique, used for the first time in compressible flows. The data reduction methodology is explained and demonstrated with measurements performed in a single-stage high-pressure turbine mounted in the compression tube facility of the von Karman Institute. The turbine was operated at subsonic and transonic pressure ratios (2.4 and 5.1) for a Reynolds number of 10{sup 6}, representative of modern engine conditions. Complete maps of the unsteady flow angle and rotor outlet Mach number are documented. These data allow the study of secondary flows and rotor trailing edge shocks. (orig.)

  10. Single-hole in situ thermal probe for hydrothermal characterization at Yucca Mountain

    International Nuclear Information System (INIS)

    Danko, G.

    1993-01-01

    The REKA thermal probe method, which uses a single borehole to measure in situ rock thermophysical properties and provides for efficient and low-cost site characterization, is analyzed for its application to hydrothermal system characterization. It is demonstrated throughout the evaluation of several temperature fields obtained for different thermal zones that the REKA method can be applied to simultaneously determine (1) two independent thermophysical properties, i.e., heat conductivity and thermal diffusivity and (2) a set of heat transport parameters, which can be used to characterize the behavior of a hydrothermal system. Based on the direct physical meaning of these transport parameters, the components of the heat transport mechanism in a given time and location of the hydrothermal system can be described. This evaluation can be applied to characterizing and quantifying in situ rock dry-out and condensate shedding at the proposed repository site

  11. Laser-Hole Boring into Overdense Plasmas Measured with Soft X-Ray Laser Probing

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, K [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Kodama, R [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Tanaka, K A [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Hashimoto, H [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Kato, Y [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Mima, K [Institute of Laser Engineering, Osaka University, Yamada Oka 2-6, Suita, Osaka 565-0871, (Japan); Weber, F A [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Barbee, Jr, T W [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Da Silva, L B [University of California, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

    2000-03-13

    A laser self-focused channel formation into overdense plasmas was observed using a soft x-ray laser probe system with a grid image refractometry (GIR) technique. 1.053 {mu}m laser light with a 100 ps pulse duration was focused onto a preformed plasma at an intensity of 2x10{sup 17} W /cm{sup 2} . Cross sections of the channel were obtained which show a 30 {mu}m diameter in overdense plasmas. The channel width in the overdense region was kept narrow as a result of self-focusing. Conically diverging density ridges were also observed along the channel, indicating a Mach cone created by a shock wave due to the supersonic propagation of the channel front. (c) 2000 The American Physical Society.

  12. Laser-Hole Boring into Overdense Plasmas Measured with Soft X-Ray Laser Probing

    International Nuclear Information System (INIS)

    Takahashi, K.; Kodama, R.; Tanaka, K. A.; Hashimoto, H.; Kato, Y.; Mima, K.; Weber, F. A.; Barbee, T. W. Jr.; Da Silva, L. B.

    2000-01-01

    A laser self-focused channel formation into overdense plasmas was observed using a soft x-ray laser probe system with a grid image refractometry (GIR) technique. 1.053 μm laser light with a 100 ps pulse duration was focused onto a preformed plasma at an intensity of 2x10 17 W /cm 2 . Cross sections of the channel were obtained which show a 30 μm diameter in overdense plasmas. The channel width in the overdense region was kept narrow as a result of self-focusing. Conically diverging density ridges were also observed along the channel, indicating a Mach cone created by a shock wave due to the supersonic propagation of the channel front. (c) 2000 The American Physical Society

  13. Probing the universality of synchronised hair around rotating black holes with Q-clouds

    Science.gov (United States)

    Herdeiro, Carlos; Kunz, Jutta; Radu, Eugen; Subagyo, Bintoro

    2018-04-01

    Recently, various families of black holes (BHs) with synchronised hair have been constructed. These are rotating BHs surrounded, as fully non-linear solutions of the appropriate Einstein-matter model, by a non-trivial bosonic field in synchronised rotation with the BH horizon. Some families bifurcate globally from a bald BH (e.g. the Kerr BH), whereas others bifurcate only locally from a bald BH (e.g. the D = 5 Myers-Perry BH). It would be desirable to understand how generically synchronisation allows hairy BHs to bifurcate from bald ones. However, the construction and scanning of the domain of existence of the former families of BHs can be a difficult and time consuming (numerical) task. Here, we first provide a simple perturbative argument to understand the generality of the synchronisation condition. Then, we observe that the study of Q-clouds is a generic tool to establish the existence of BHs with synchronised hair bifurcating (globally or locally) from a given bald BH without having to solve the fully non-linear coupled system of Einstein-matter equations. As examples, we apply this tool to establish the existence of synchronised hair around D = 6 Myers-Perry BHs, D = 5 black rings and D = 4 Kerr-AdS BHs, where D is the spacetime dimension. The black rings case provides an example of BHs with synchronised hair beyond spherical horizon topology, further establishing the generality of the mechanism.

  14. Scaling behavior of free-volume holes in polymers probed by positron annihilation

    Science.gov (United States)

    Wang, C. L.; Wang, S. J.

    1995-04-01

    Positron lifetimes in polybutadiene (PB) and polypropylene (PP) are measured as functions of temperature in the range 95-305 K and 95-370 K, respectively. From the variations of ortho-positronium (o-Ps) lifetime τ3, we have determined the glass transition temperatures Tg in PB and PP and the excluding temperature Te in PB, beyond which the o-Ps lifetime τ3 in PB is saturated. From the analogy of the temperature-dependent o-Ps intensity I3 in PB and PP, high- and low-density polyethylene (HDPE and LDPE), we propose that above the glass transition temperature Tg the o-Ps intensity I3 exhibits the scaling relation I3~(T-Tg)β in these polymers. The data also indicate the existence of a crossover temperature Tc, located above Tg, where the β value changes greatly. When TgHDPE and LDPE [D. Lin and S. J. Wang, J. Phys. Condens. Matter 4, 3331 (1992)]. The β values in the region of TcHDPE and branched LDPE, respectively. These results reveal a common picture of hole creation above Tg in polymers, however, the concrete value of β may be associated with the branching structure of macromolecules.

  15. Probing charge transfer dynamics in self-assembled monolayers by core hole clock approach

    International Nuclear Information System (INIS)

    Zharnikov, Michael

    2015-01-01

    This article reviews recent progress in the application of core hole clock approach in the framework of resonant Auger electron spectroscopy to the monomolecular assembles of alkyl, oligophenyl, and oligo(phenylene–ethynylene) based molecules on Au(1 1 1) substrates, referring mostly to the work by the author et al. The major goal was to study electron transfer (ET) dynamics in these systems serving as prototypes of molecular electronics (ME) devices. The ET pathway to the conductive substrate was unambiguously defined by resonant excitation of the nitrile tailgroup attached to the molecular backbone. Characteristic ET times within the femtosecond domain were determined, along with the attenuation factors for the ET dynamics, analogous to the case of the static transport. The above parameters were found to exhibit strong dependence on the character of the molecular orbital which mediates the ET process. In addition, certain spectral features, which can be associated with an inverse ET from the molecular backbone to the excitation site, were observed upon exchange of the nitrile group by strongly electronegative nitro moiety. The reported results represent a valuable input for theory and a certain potential for applications such as ME devices where optimization of ET can have significant technological impact.

  16. Calibration of a four-hole pyramid probe and area traverse measurements in a short-duration transonic turbine cascade tunnel

    Science.gov (United States)

    Main, A. J.; Day, C. R. B.; Lock, G. D.; Oldfield, M. L. G.

    1996-08-01

    A four-hole pyramid probe has been calibrated for use in a short-duration transonic turbine cascade tunnel. The probe is used to create area traverse maps of total and static pressure, and pitch and yaw angles of the flow downstream of a transonic annular cascade. This data is unusual in that it was acquired in a short-duration (5 s of run time) annular cascade blowdown tunnel. A four-hole pyramid probe was used which has a 2.5 mm section head, and has the side faces inclined at 60° to the flow to improve transonic performance. The probe was calibrated in an ejector driven, perforated wall transonic tunnel over the Mach number range 0.5 1.2, with pitch angles from -20° to + 20° and yaw angles from-23° to +23°. A computer driven automatic traversing mechanism and data collection system was used to acquire a large probe calibration matrix (˜ 10,000 readings) of non dimensional pitch, yaw, Mach number, and total pressure calibration coefficients. A novel method was used to transform the probe calibration matrix of the raw coefficients into a probe application matrix of the physical flow variables (pitch, yaw, Mach number etc.). The probe application matrix is then used as a fast look-up table to process probe results. With negligible loss of accuracy, this method is faster by two orders of magnitude than the alternative of global interpolation on the raw probe calibration matrix. The blowdown tunnel (mean nozzle guide vane blade ring diameter 1.1 m) creates engine representative Reynolds numbers, transonic Mach numbers and high levels (≈ 13%) of inlet turbulence intensity. Contours of experimental measurements at three different engine relevant conditions and two axial positions have been obtained. An analysis of the data is presented which includes a necessary correction for the finite velocity of the probe. Such a correction is non trivial for the case of fast moving probes in compressible flow.

  17. Human push capability.

    Science.gov (United States)

    Barnett, Ralph L; Liber, Theodore

    2006-02-22

    Use of unassisted human push capability arises from time to time in the areas of crowd and animal control, the security of locked doors, the integrity of railings, the removal of tree stumps and entrenched vehicles, the manoeuvering of furniture, and athletic pursuits such as US football or wrestling. Depending on the scenario, human push capability involves strength, weight, weight distribution, push angle, footwear/floor friction, and the friction between the upper body and the pushed object. Simple models are used to establish the relationships among these factors.

  18. Dispersive heterodyne probing method for laser frequency stabilization based on spectral hole burning in rare-earth doped crystals

    DEFF Research Database (Denmark)

    Gobron, Olivier; Jung, K.; Galland, N.

    2017-01-01

    Frequency-locking a laser to a spectral hole in rare-earth doped crystals at cryogenic temperature has been shown to be a promising alternative to the use of high finesse Fabry-Perot cavities when seeking a very high short term stability laser (M. J. Thorpe et al., Nature Photonics 5, 688 (2011......)). We demonstrate here a novel technique for achieving such stabilization, based on generating a heterodyne beat-note between a master laser and a slave laser whose dephasing caused by propagation near a spectral hole generate the error signal of the frequency lock. The master laser is far detuned from...

  19. Probing the Magnetic Field Structure in Sgr A* on Black Hole Horizon Scales with Polarized Radiative Transfer Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gold, Roman; McKinney, Jonathan C. [Department of Physics and Joint Space-Science Institute, University of Maryland, College Park, MD 20742 (United States); Johnson, Michael D.; Doeleman, Sheperd S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-03-10

    Magnetic fields are believed to drive accretion and relativistic jets in black hole accretion systems, but the magnetic field structure that controls these phenomena remains uncertain. We perform general relativistic (GR) polarized radiative transfer of time-dependent three-dimensional GR magnetohydrodynamical simulations to model thermal synchrotron emission from the Galactic Center source Sagittarius A* (Sgr A*). We compare our results to new polarimetry measurements by the Event Horizon Telescope (EHT) and show how polarization in the visibility (Fourier) domain distinguishes and constrains accretion flow models with different magnetic field structures. These include models with small-scale fields in disks driven by the magnetorotational instability as well as models with large-scale ordered fields in magnetically arrested disks. We also consider different electron temperature and jet mass-loading prescriptions that control the brightness of the disk, funnel-wall jet, and Blandford–Znajek-driven funnel jet. Our comparisons between the simulations and observations favor models with ordered magnetic fields near the black hole event horizon in Sgr A*, though both disk- and jet-dominated emission can satisfactorily explain most of the current EHT data. We also discuss how the black hole shadow can be filled-in by jet emission or mimicked by the absence of funnel jet emission. We show that stronger model constraints should be possible with upcoming circular polarization and higher frequency (349 GHz) measurements.

  20. PushPull++

    KAUST Repository

    Lipp, Markus; Wonka, Peter; Mü ller, Pascal

    2014-01-01

    PushPull tools are implemented in most commercial 3D modeling suites. Their purpose is to intuitively transform a face, edge, or vertex, and then to adapt the polygonal mesh locally. However, previous approaches have limitations: Some allow

  1. Particle Engulfment and Pushing

    Science.gov (United States)

    2001-01-01

    As a liquefied metal solidifies, particles dispersed in the liquid are either pushed ahead of or engulfed by the moving solidification front. Similar effects can be seen when the ground freezes and pushes large particles out of the soil. The Particle Engulfment and Pushing (PEP) experiment, conducted aboard the fourth U.S. Microgravity Payload (USMP-4) mission in 1997, used a glass and plastic beads suspended in a transparent liquid. The liquid was then frozen, trapping or pushing the particles as the solidifying front moved. This simulated the formation of advanced alloys and composite materials. Such studies help scientists to understand how to improve the processes for making advanced materials on Earth. The principal investigator is Dr. Doru Stefanescu of the University of Alabama. This image is from a video downlink.

  2. Casingless down-hole for sealing an ablation volume and obtaining a sample for analysis

    Science.gov (United States)

    Noble, Donald T.; Braymen, Steven D.; Anderson, Marvin S.

    1996-10-01

    A casing-less down hole sampling system for acquiring a subsurface sample for analysis using an inductively coupled plasma system is disclosed. The system includes a probe which is pushed into the formation to be analyzed using a hydraulic ram system. The probe includes a detachable tip member which has a soil point mad a barb, with the soil point aiding the penetration of the earth, and the barb causing the tip member to disengage from the probe and remain in the formation when the probe is pulled up. The probe is forced into the formation to be tested, and then pulled up slightly, to disengage the tip member and expose a column of the subsurface formation to be tested. An instrumentation tube mounted in the probe is then extended outward from the probe to longitudinally extend into the exposed column. A balloon seal mounted on the end of the instrumentation tube allows the bottom of the column to be sealed. A source of laser radiation is emitted from the instrumentation tube to ablate a sample from the exposed column. The instrumentation tube can be rotated in the probe to sweep the laser source across the surface of the exposed column. An aerosol transport system carries the ablated sample from the probe to the surface for testing in an inductively coupled plasma system. By testing at various levels in the down-hole as the probe is extracted from the soil, a profile of the subsurface formation may be obtained.

  3. New probe of dark-matter properties: gravitational waves from an intermediate-mass black hole embedded in a dark-matter minispike.

    Science.gov (United States)

    Eda, Kazunari; Itoh, Yousuke; Kuroyanagi, Sachiko; Silk, Joseph

    2013-05-31

    An intermediate-mass black hole (IMBH) may have a dark-matter (DM) minihalo around it and develop a spiky structure within less than a parsec from the IMBH. When a stellar mass object is captured by the minihalo, it eventually infalls into such an IMBH due to gravitational wave backreaction which in turn could be observed directly by future space-borne gravitational wave experiments such as eLISA and NGO. In this Letter, we show that the gravitational wave (GW) detectability strongly depends on the radial profile of the DM distribution. So if the GW is detected, the power index, that is, the DM density distribution, would be determined very accurately. The DM density distribution obtained would make it clear how the IMBH has evolved from a seed black hole and whether the IMBH has experienced major mergers in the past. Unlike the γ-ray observations of DM annihilation, GW is just sensitive to the radial profile of the DM distribution and even to noninteracting DM. Hence, the effect we demonstrate here can be used as a new and powerful probe into DM properties.

  4. PushPull++

    KAUST Repository

    Lipp, Markus

    2014-07-22

    PushPull tools are implemented in most commercial 3D modeling suites. Their purpose is to intuitively transform a face, edge, or vertex, and then to adapt the polygonal mesh locally. However, previous approaches have limitations: Some allow adjustments only when adjacent faces are orthogonal; others support slanted surfaces but never create new details. Moreover, self-intersections and edge-collapses during editing are either ignored or work only partially for solid geometry. To overcome these limitations, we introduce the PushPull++ tool for rapid polygonal modeling. In our solution, we contribute novel methods for adaptive face insertion, adjacent face updates, edge collapse handling, and an intuitive user interface that automatically proposes useful drag directions. We show that PushPull++ reduces the complexity of common modeling tasks by up to an order of magnitude when compared with existing tools. Copyright © ACM.

  5. Trustworthy content push

    OpenAIRE

    Kuntze, Nicolai; Schmidt, Andreas U.

    2006-01-01

    Delivery of content to mobile devices gains increasing importance in industrial environments to support employees in the field. An important application are e-mail push services like the fashionable Blackberry. These systems are facing security challenges regarding data transport to, and storage of the data on the end user equipment. The emerging Trusted Computing technology offers new answers to these open questions.

  6. Push-Back Leadership.

    Science.gov (United States)

    Tetenbaum, Toby J.; Tetenbaum, Hilary

    2003-01-01

    Describes push-back leadership, a model of leadership based on the work of Ronald Heifetz and Martin Linksky. Argues that the two key roles of the leader are to give the work back to people and to keep them within a healthy range of disequilibrium that generates creativity and innovation to solve organizational problems. (Author/LRW)

  7. Push-out strength of modified Portland cements and resins.

    Science.gov (United States)

    Iacono, Francesco; Gandolfi, Maria Giovanna; Huffman, Bradford; Sword, Jeremy; Agee, Kelli; Siboni, Francesco; Tay, Franklin; Prati, Carlo; Pashley, David

    2010-02-01

    Modified calcium-silicate cements derived from white Portland cement (PC) were formulated to test their push-out strength from radicular dentin after immersion for 1 month. Slabs obtained from 42 single-rooted extracted teeth were prepared with 0.6 mm diameter holes, then enlarged with rotary instruments. After immersion in EDTA and NaOC1, the holes were filled with modified PCs or ProRoot MTA, Vitrebond and Clearfil SE. Different concentrations of phyllosilicate (montmorillonite-MMT) were added to experimental cements. ProRoot MTA was also included as reference material. Vitrebond and Clearfil SE were included as controls. Each group was tested after 1 month of immersion in water or PBS. A thin-slice push-out test on a universal testing machine served to test the push-out strength of materials. Results were statistically analyzed using the least squares means (LSM) method. The modified PCs had push-out strengths of 3-9.5 MPa after 1 month of immersion in water, while ProRoot MTA had 4.8 MPa. The push-out strength of PC fell after incubation in PBS for 1 month, while the push-out strength of ProRoot MTA increased. There were no significant changes in Clearfil SE Bond or Vitrebond after water or PBS storage.

  8. Electronic correlations in the hole-doped superconductor RbFe{sub 2}As{sub 2} probed via {sup 75}As NMR

    Energy Technology Data Exchange (ETDEWEB)

    Molatta, S.; Wosnitza, J. [Hochfeld-Magnetlabor Dresden (HLD), Helmholtz-Zentrum Dresden-Rossendorf (Germany); TU Dresden (Germany); DFG, GRK-1621 (Germany); Zhang, Z.; Dmytriieva, D.; Kuehne, H. [Hochfeld-Magnetlabor Dresden (HLD), Helmholtz-Zentrum Dresden-Rossendorf (Germany); Khim, S.; Grafe, H.J. [IFW Dresden (Germany); Wurmehl, S.; Buechner, B. [TU Dresden (Germany); DFG, GRK-1621 (Germany); IFW Dresden (Germany)

    2016-07-01

    We will present latest {sup 75}As NMR data in the normal state of the stoichiometric superconductor RbFe{sub 2}As{sub 2}. This will be put into context to known results for the heavily hole-doped compound KFe{sub 2}As{sub 2}. The static and dynamic magnetic correlations were probed via measurements of the Knight shift and nuclear spin-lattice relaxation rate in a wide temperature range from 0.3 to 300 K. Although neither a magnetic nor a structural transition were observed down to lowest temperatures, the very close proximity of the ground state to a magnetic instability is indicated by a pronounced Curie-Weiss-like behavior of spin fluctuations. At around 100 K, we find a maximum of the Knight shift and a changing exponent of the temperature-dependent relaxation rate. This is phenomenologically similar to the case of KFe{sub 2}As{sub 2} and was proposed to stem from a incoherence-coherence crossover mechanism of electronic correlations.

  9. Femtosecond nonlinear spectroscopy at surfaces: Second-harmonic probing of hole burning at the Si(111)7x7 surface and Fourier-transform sum-frequency vibrational spectroscopy

    International Nuclear Information System (INIS)

    McGuire, John Andrew

    2004-01-01

    The high temporal resolution and broad bandwidth of a femtosecond laser system are exploited in a pair of nonlinear optical studies of surfaces. The dephasing dynamics of resonances associated with the adatom dangling bonds of the Si(111)7 x 7 surface are explored by transient second-harmonic hole burning, a process that can be described as a fourth-order nonlinear optical process. Spectral holes produced by a 100 fs pump pulse at about 800 nm are probed by the second harmonic signal of a 100 fs pulse tunable around 800 nm. The measured spectral holes yield homogeneous dephasing times of a few tens of femtoseconds. Fits with a Lorentzian spectral hole centered at zero probe detuning show a linear dependence of the hole width on pump fluence, which suggests that charge carrier-carrier scattering dominates the dephasing dynamics at the measured excitation densities. Extrapolation of the deduced homogeneous dephasing times to zero excitation density yields an intrinsic dephasing time of ∼ 70 fs. The presence of a secondary spectral hole indicates that scattering of the surface electrons with surface optical phonons at 570 cm -1 occurs within the first 200 fs after excitation. The broad bandwidth of femtosecond IR pulses is used to perform IR-visible sum frequency vibrational spectroscopy. By implementing a Fourier-transform technique, we demonstrate the ability to obtain sub-laser-bandwidth spectral resolution. FT-SFG yields a greater signal when implemented with a stretched visible pulse than with a femtosecond visible pulse. However, when compared with multichannel spectroscopy using a femtosecond IR pulse but a narrowband visible pulse, Fourier-transform SFG is found to have an inferior signal-to-noise ratio. A mathematical analysis of the signal-to-noise ratio illustrates the constraints on the Fourier-transform approach

  10. Femtosecond nonlinear spectroscopy at surfaces: Second-harmonic probing of hole burning at the Si(111)7x7 surface and fourier-transform sum-frequency vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, John Andrew [Univ. of California, Berkeley, CA (United States)

    2004-11-24

    The high temporal resolution and broad bandwidth of a femtosecond laser system are exploited in a pair of nonlinear optical studies of surfaces. The dephasing dynamics of resonances associated with the adatom dangling bonds of the Si(111)7 x 7 surface are explored by transient second-harmonic hole burning, a process that can be described as a fourth-order nonlinear optical process. Spectral holes produced by a 100 fs pump pulse at about 800 nm are probed by the second harmonic signal of a 100 fs pulse tunable around 800 nm. The measured spectral holes yield homogeneous dephasing times of a few tens of femtoseconds. Fits with a Lorentzian spectral hole centered at zero probe detuning show a linear dependence of the hole width on pump fluence, which suggests that charge carrier-carrier scattering dominates the dephasing dynamics at the measured excitation densities. Extrapolation of the deduced homogeneous dephasing times to zero excitation density yields an intrinsic dephasing time of {approx} 70 fs. The presence of a secondary spectral hole indicates that scattering of the surface electrons with surface optical phonons at 570 cm-1 occurs within the first 200 fs after excitation. The broad bandwidth of femtosecond IR pulses is used to perform IR-visible sum frequency vibrational spectroscopy. By implementing a Fourier-transform technique, we demonstrate the ability to obtain sub-laser-bandwidth spectral resolution. FT-SFG yields a greater signal when implemented with a stretched visible pulse than with a femtosecond visible pulse. However, when compared with multichannel spectroscopy using a femtosecond IR pulse but a narrowband visible pulse, Fourier-transform SFG is found to have an inferior signal-to-noise ratio. A mathematical analysis of the signal-to-noise ratio illustrates the constraints on the Fourier-transform approach.

  11. Reynolds number effects on the non-nulling calibration of a cone-type five-hole probe for turbomachinery applications

    International Nuclear Information System (INIS)

    Lee, Sang Woo; Jun, Sang Bae

    2005-01-01

    The effects of Reynolds number on the non-nulling calibration of a typical cone-type five-hole probe have been investigated for the representative Reynolds numbers in turbomachinery. The pitch and yaw angles are changed from -35 degrees to 35 degrees with an angle interval of 5 degrees at six probe Reynolds numbers in range between 6.60x10 3 and 3.17x10 4 . The result shows that not only each calibration coefficient itself but also its Reynolds number dependency is affected significantly by the pitch and yaw angles. The Reynolds-number effects on the pitch-and yaw-angle coefficients are noticeable when the absolute values of the pitch and yaw angles are smaller than 20 degrees. The static-pressure coefficient is sensitive to the Reynolds number nearly all over the pitch-and yaw-angle range. The Reynolds-number effect on the total-pressure coefficient is found remarkable when the absolute values of the pitch and yaw angles are larger than 20 degrees. Through a typical non-nulling reduction procedure, actual reduced values of the pitch and yaw angles, static and total pressures, and velocity magnitude at each Reynolds number are obtained by employing the calibration coefficients at the highest Reynolds number (Re=3.17x10 4 ) as input reference calibration data. As a result, it is found that each reduced value has its own unique trend depending on the pitch and yaw angles. Its general tendency is related closely to the variation of the corresponding calibration coefficient with the Reynolds number. Among the reduced values, the reduced total pressure suffers the most considerable deviation from the measured one and its dependency upon the pitch and yaw angles is most noticeable. In this study, the root-mean-square data as well as the upper and lower bounds of the reduced values are reported as a function of the Reynolds number. These data would be very useful in the estimation of the Reynolds-number effects on the non-nulling calibration

  12. Investigating the Binarity of S0-2: Implications for Its Origins and Robustness as a Probe of the Laws of Gravity around a Supermassive Black Hole

    Science.gov (United States)

    Chu, Devin S.; Do, Tuan; Hees, Aurelien; Ghez, Andrea; Naoz, Smadar; Witzel, Gunther; Sakai, Shoko; Chappell, Samantha; Gautam, Abhimat K.; Lu, Jessica R.; Matthews, Keith

    2018-02-01

    The star S0-2, which orbits the supermassive black hole (SMBH) in our Galaxy with a period of 16 years, provides the strongest constraint on both the mass of the SMBH and the distance to the Galactic center. S0-2 will soon provide the first measurement of relativistic effects near a SMBH. We report the first limits on the binarity of S0-2 from radial velocity (RV) monitoring, which has implications for both understanding its origin and robustness as a probe of the central gravitational field. With 87 RV measurements, which include 12 new observations that we present, we have the requisite data set to look for RV variations from S0-2‧s orbital model. Using a Lomb–Scargle analysis and orbit-fitting for potential binaries, we detect no RV variation beyond S0-2‧s orbital motion and do not find any significant periodic signal. The lack of a binary companion does not currently distinguish different formation scenarios for S0-2. The upper limit on the mass of a companion star ({M}{comp}) still allowed by our results has a median upper limit of {M}{comp} sin i ≤ 1.6 M ⊙ for periods between 1 and 150 days, the longest period to avoid tidal break-up of the binary. We also investigate the impact of the remaining allowed binary system on the measurement of the relativistic redshift at S0-2‧s closest approach in 2018. While binary star systems are important to consider for this experiment, we find that plausible binaries for S0-2 will not alter a 5σ detection of the relativistic redshift.

  13. Black hole decay as geodesic motion

    International Nuclear Information System (INIS)

    Gupta, Kumar S.; Sen, Siddhartha

    2003-01-01

    We show that a formalism for analyzing the near-horizon conformal symmetry of Schwarzschild black holes using a scalar field probe is capable of describing black hole decay. The equation governing black hole decay can be identified as the geodesic equation in the space of black hole masses. This provides a novel geometric interpretation for the decay of black holes. Moreover, this approach predicts a precise correction term to the usual expression for the decay rate of black holes

  14. Counting probe

    International Nuclear Information System (INIS)

    Matsumoto, Haruya; Kaya, Nobuyuki; Yuasa, Kazuhiro; Hayashi, Tomoaki

    1976-01-01

    Electron counting method has been devised and experimented for the purpose of measuring electron temperature and density, the most fundamental quantities to represent plasma conditions. Electron counting is a method to count the electrons in plasma directly by equipping a probe with the secondary electron multiplier. It has three advantages of adjustable sensitivity, high sensitivity of the secondary electron multiplier, and directional property. Sensitivity adjustment is performed by changing the size of collecting hole (pin hole) on the incident front of the multiplier. The probe is usable as a direct reading thermometer of electron temperature because it requires to collect very small amount of electrons, thus it doesn't disturb the surrounding plasma, and the narrow sweep width of the probe voltage is enough. Therefore it can measure anisotropy more sensitively than a Langmuir probe, and it can be used for very low density plasma. Though many problems remain on anisotropy, computer simulation has been carried out. Also it is planned to provide a Helmholtz coil in the vacuum chamber to eliminate the effect of earth magnetic field. In practical experiments, the measurement with a Langmuir probe and an emission probe mounted to the movable structure, the comparison with the results obtained in reverse magnetic field by using a Helmholtz coil, and the measurement of ionic sound wave are scheduled. (Wakatsuki, Y.)

  15. Imagine the Universe! The Anatomy of Black Holes. Probing the Structure & Evolution of the Cosmos. An Information and Activity Booklet. Grades 9-12, 1998-1999.

    Science.gov (United States)

    Whitlock, Laura A.; Granger, Kara C.; Mahon, Jane D.

    The information provided in this booklet is meant to give the necessary background information so that the science of black holes can be taught confidently to secondary students. The featured activities can be used to engage and excite students about the topic of black holes in different disciplines and in a number of ways. Activities include: (1)…

  16. Boris push with spatial stepping

    International Nuclear Information System (INIS)

    Penn, G; Stoltz, P H; Cary, J R; Wurtele, J

    2003-01-01

    The Boris push is commonly used in plasma physics simulations because of its speed and stability. It is second-order accurate, requires only one field evaluation per time step, and has good conservation properties. However, for accelerator simulations it is convenient to propagate particles in z down a changing beamline. A 'spatial Boris push' algorithm has been developed which is similar to the Boris push but uses a spatial coordinate as the independent variable, instead of time. This scheme is compared to the fourth-order Runge-Kutta algorithm, for two simplified muon beam lattices: a uniform solenoid field, and a 'FOFO' lattice where the solenoid field varies sinusoidally along the axis. Examination of the canonical angular momentum, which should be conserved in axisymmetric systems, shows that the spatial Boris push improves accuracy over long distances

  17. Black holes

    International Nuclear Information System (INIS)

    Feast, M.W.

    1981-01-01

    This article deals with two questions, namely whether it is possible for black holes to exist, and if the answer is yes, whether we have found any yet. In deciding whether black holes can exist or not the central role in the shaping of our universe played by the forse of gravity is discussed, and in deciding whether we are likely to find black holes in the universe the author looks at the way stars evolve, as well as white dwarfs and neutron stars. He also discusses the problem how to detect a black hole, possible black holes, a southern black hole, massive black holes, as well as why black holes are studied

  18. Black holes

    OpenAIRE

    Brügmann, B.; Ghez, A. M.; Greiner, J.

    2001-01-01

    Recent progress in black hole research is illustrated by three examples. We discuss the observational challenges that were met to show that a supermassive black hole exists at the center of our galaxy. Stellar-size black holes have been studied in x-ray binaries and microquasars. Finally, numerical simulations have become possible for the merger of black hole binaries.

  19. f-electron systems: pushing band theory

    International Nuclear Information System (INIS)

    Koelling, D.D.

    1991-01-01

    The f-electron orbitrals have always been the ''incomplete atomic shells acting as local moments, and weakly interacting with the remaining electronic structure'' in the minds of most people. So examining them using a band theory where one views them as itinerant was once - and to some extent even today still is - considered with some skepticism. Nonetheless, a very significant community has successfully utilized band theory as a probe of the electronic structure of the appropriate actinides and rare earths. Those people actually using the approach would be the first to declare that it is not the whole solution. Instead, one is pushing and even exceeding its limit of applicability. However, the apropriate procedure is to push the model consistently to its limits, patch where possible, and then look to see where discrepancies remain. I propose to offer a selected review of past developments (emphasizing the career to data of A.J. Freeman in this area), offer a list of interesting puzzles for the future, and then make some guesses as to the techniques one might want to use. (orig.)

  20. Push piece for spent fuel elements magazine

    International Nuclear Information System (INIS)

    Griveau, R.; Kerlau, D.; Tucoulat, D.; Colas, J.; Pellier, R.

    1989-01-01

    The push piece permits the displacement of little section elements in a magazine of high section. At the end of cut, the push piece leans its flank against an auxiliary blank holder and the element is pushed by a paddle, the push piece being immobilized [fr

  1. Probing the quantum correlation and Bell non-locality for Dirac particles with Hawking effect in the background of Schwarzschild black hole

    International Nuclear Information System (INIS)

    Xu, Shuai; Song, Xue-ke; Shi, Jia-dong; Ye, Liu

    2014-01-01

    In this Letter, we analytically explore the effect of the Hawking radiation on the quantum correlation and Bell non-locality for Dirac particles in the background of Schwarzschild black hole. It is shown that when the Hawking effect is almost nonexistent, corresponding to the case of an almost extreme black hole, the quantum properties of physically accessible state are the same for the initial situation. For finite Hawking temperature T, the accessible quantum correlation monotonously decreases along with increasing T owing to the thermal fields generated by the Hawking effect, and the accessible quantum non-locality will be disappeared when the Hawking temperature is more than a fixed value which increases with the parameter r of Werner state growing. Then we analyze the redistribution of quantum correlation, and find that for the case of the Hawking temperature being infinite, corresponding to the case of the black hole evaporating completely, the quantum correlation of physically accessible state is equal to the one of the inaccessible states. Moreover, due to the Pauli exclusion principle and the differences between Fermi–Dirac and Bose–Einstein statistics, for the Dirac fields the accessible classical correlation decreases with increase of the Hawking temperature, which is different for the scalar fields. For Bell non-locality, we also find that the quantum non-locality is always extinct for physically inaccessible states, and the strength of the non-locality decreases with enlarging intensity of Hawking effect when the non-locality is existent in physically accessible state.

  2. Observability of Quantum State of Black Hole

    CERN Document Server

    David, J R; Mandal, G; Wadia, S R; David, Justin R.; Dhar, Avinash; Mandal, Gautam; Wadia, Spenta R.

    1997-01-01

    We analyze terms subleading to Rutherford in the $S$-matrix between black hole and probes of successively high energies. We show that by an appropriate choice of the probe one can read off the quantum state of the black hole from the S-matrix, staying asymptotically far from the BH all the time. We interpret the scattering experiment as scattering off classical stringy backgrounds which explicitly depend on the internal quantum numbers of the black hole.

  3. Plasma electron hole kinematics. I. Momentum conservation

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, I. H.; Zhou, C. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2016-08-15

    We analyse the kinematic properties of a plasma electron hole: a non-linear self-sustained localized positive electric potential perturbation, trapping electrons, which behaves as a coherent entity. When a hole accelerates or grows in depth, ion and electron plasma momentum is changed both within the hole and outside, by an energization process we call jetting. We present a comprehensive analytic calculation of the momentum changes of an isolated general one-dimensional hole. The conservation of the total momentum gives the hole's kinematics, determining its velocity evolution. Our results explain many features of the behavior of hole speed observed in numerical simulations, including self-acceleration at formation, and hole pushing and trapping by ion streams.

  4. Pushing Boundaries while Maintaining Stability

    DEFF Research Database (Denmark)

    Lippke, Lena; Wegener, Charlotte

    at the same time. The exploration of transforming practices shows how disturbances in relation to the ‘normal’ practices are created and thus makes invisible conventions which are taken for granted visible. Thus, this paper addresses two types of invisibility: the unnoticed boundary-pushing practices...

  5. 'Mister Badger' Pushing Mars Rock

    Science.gov (United States)

    1976-01-01

    Viking's soil sampler collector arm successfully pushed a rock on the surface of Mars during the afternoon of Friday, October 8. The irregular-shaped rock was pushed several inches by the Lander's collector arm, which displaced the rock to the left of its original position, leaving it cocked slightly upward. Photographs and other information verified the successful rock push. Photo at left shows the soil sampler's collector head pushing against the rock, named 'Mister Badger' by flight controllers. Photo at right shows the displaced rock and the depression whence it came. Part of the soil displacement was caused by the collector s backhoe. A soil sample will be taken from the site Monday night, October 11. It will then be delivered to Viking s organic chemistry instrument for a series of analyses during the next few weeks. The sample is being sought from beneath a rock because scientists believe that, if there are life forms on Mars, they may seek rocks as shelter from the Sun s intense ultraviolet radiation.

  6. Push for the Second Screen

    DEFF Research Database (Denmark)

    Sørensen, Jannick Kirk; Sørensen, Lene Tolstrup

    Users’ perception of the relation between the TV screen and a secondary screen (e.g. smartphone or tablet) is examined empirically in a pilot project through a low-fi prototype and interviews. Early observations indicate that the user value/acceptance of push-messages delivered to the second screen...

  7. Black Holes

    OpenAIRE

    Townsend, P. K.

    1997-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usu...

  8. Black Holes

    OpenAIRE

    Horowitz, Gary T.; Teukolsky, Saul A.

    1998-01-01

    Black holes are among the most intriguing objects in modern physics. Their influence ranges from powering quasars and other active galactic nuclei, to providing key insights into quantum gravity. We review the observational evidence for black holes, and briefly discuss some of their properties. We also describe some recent developments involving cosmic censorship and the statistical origin of black hole entropy.

  9. PUSH-ing Construction Communications & Going Viral for Safety

    OpenAIRE

    Prevost, Dan; McCall, Bill

    2018-01-01

    Over the past 2 years, the Indiana Toll Road Concession Co. (ITRCC) and its contractors have delivered the 80/90 PUSH project, an ambitious rehabilitation of 70 miles of the Indiana Toll Road. The team developed an aggressive communications program to keep its customers and community stakeholders informed, partnering with the Indiana Motor Truck Association to take its Put the Phone Down campaign to social media. Join us for a discussion.

  10. Push-pull quinoidal porphyrins.

    Science.gov (United States)

    Smith, Martin J; Blake, Iain M; Clegg, William; Anderson, Harry L

    2018-05-01

    A family of push-pull quinoidal porphyrin monomers has been prepared from a meso-formyl porphyrin by bromination, thioacetal formation, palladium-catalyzed coupling with malononitrile and oxidation with DDQ. Attempts at extending this synthesis to a push-pull quinoidal/cumulenic porphyrin dimer were not successful. The crystal structures of the quinoidal porphyrins indicate that there is no significant contribution from singlet biradical or zwitterionic resonance forms. The crystal structure of an ethyne-linked porphyrin dimer shows that the torsion angle between the porphyrin units is only about 3°, in keeping with crystallographic results on related compounds, but contrasting with the torsion angle of about 35° predicted by computational studies. The free-base quinoidal porphyrin monomers form tightly π-stacked layer structures, despite their curved geometries and bulky aryl substituents.

  11. Pushing hard on the accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1987-09-15

    The quest for new techniques to drive future generations of particle accelerators has been pushed hard in recent years, efforts having been highlighted by workshops in Europe, organized by the European Committee for Future Accelerators, and in the US. The latest ECFA Workshop on New Developments in Particle Acceleration Techniques, held at Orsay from 29 June to 4 July, showed how the initial frantic search for innovation is now maturing.

  12. 33 CFR 90.3 - Pushing vessel and vessel being pushed: Composite unit.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Pushing vessel and vessel being... HOMELAND SECURITY INLAND NAVIGATION RULES INLAND RULES: INTERPRETATIVE RULES § 90.3 Pushing vessel and vessel being pushed: Composite unit. Rule 24(b) of the Inland Rules states that when a pushing vessel and...

  13. 33 CFR 82.3 - Pushing vessel and vessel being pushed: Composite unit.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Pushing vessel and vessel being... HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES 72 COLREGS: INTERPRETATIVE RULES § 82.3 Pushing vessel and vessel being pushed: Composite unit. Rule 24(b) of the 72 COLREGS states that when a pushing vessel and a...

  14. New class of accelerating black hole solutions

    International Nuclear Information System (INIS)

    Camps, Joan; Emparan, Roberto

    2010-01-01

    We construct several new families of vacuum solutions that describe black holes in uniformly accelerated motion. They generalize the C metric to the case where the energy density and tension of the strings that pull (or push) on the black holes are independent parameters. These strings create large curvatures near their axis and when they have infinite length they modify the asymptotic properties of the spacetime, but we discuss how these features can be dealt with physically, in particular, in terms of 'wiggly cosmic strings'. We comment on possible extensions and extract lessons for the problem of finding higher-dimensional accelerating black hole solutions.

  15. CSS3 pushing the limits

    CERN Document Server

    Greig, Stephen

    2013-01-01

    Push CSS3 and your design skills to the limit-and beyond! Representing an evolutionary leap forward for CSS, CSS3 is chock-full of new capabilities that dramatically expand the boundaries of what a styling language can do. But many of those new features remain undocumented, making it difficult to learn what they are and how to use them to create the sophisticated sites and web apps clients demand and users have grown to expect. Until now. This book introduces you to all of CSS3's new and advanced features, and, with the help of dozens of real-world examples and live

  16. SA in nuclear power push

    International Nuclear Information System (INIS)

    Anon.

    1982-01-01

    Uranium research takes on a new lease of life as South Africa pushes ahead with a two-pronged attack on future energy needs. The recent allocation to the Department of Mineral and Energy Affairs of more than R106 million for atomic energy research indicates that South Africa's heavy commitment to nuclear spending involves not only the Koeberg power station, with its two pressurised water reactors, but also a uranium enrichment plant that is expected to be in commercial production by 1985. Other countries' expenditures on nuclear activities are also discussed

  17. Foot placement strategy in pushing and pulling.

    Science.gov (United States)

    Lee, Tzu-Hsien

    2018-01-01

    Pushing and pulling tasks are very common in daily and industrial workplaces. They are one major source of musculoskeletal complaints. This study aimed to examine the foot placement strategy while pushing and pulling. Thirteen young males and ten young females were recruited as participants. A two (pushing and pulling) by four (48 cm, 84 cm, 120 cm, and 156 cm) factorial design was used. Exertion direction and exertion height significantly affected foot placement strategy. Pushing task needed more anteroposterior space than pulling task. The percentages of female/male for trailing foot position ranged from 77% to 90% (pushing) and from 80% to 93% (pulling) across the exertion heights. Practitioners should provide an anteroposterior space approximately to 70% body stature for workers to exert their maximum pulling and pushing strengths.

  18. Android programming pushing the limits

    CERN Document Server

    Hellman, Erik

    2013-01-01

    Unleash the power of the Android OS and build the kinds of brilliant, innovative apps users love to use If you already know your way around the Android OS and can build a simple Android app in under an hour, this book is for you. If you're itching to see just how far you can push it and discover what Android is really capable of, it's for you. And if you're ready to learn how to build advanced, intuitive, innovative apps that are a blast to use, this book is definitely for you. From custom views and advanced multi-touch gestures, to integrating online web services and exploiting the latest

  19. The Antartic Ice Borehole Probe

    Science.gov (United States)

    Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.

    2000-01-01

    The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

  20. Brane holes

    International Nuclear Information System (INIS)

    Frolov, Valeri P.; Mukohyama, Shinji

    2011-01-01

    The aim of this paper is to demonstrate that in models with large extra dimensions under special conditions one can extract information from the interior of 4D black holes. For this purpose we study an induced geometry on a test brane in the background of a higher-dimensional static black string or a black brane. We show that, at the intersection surface of the test brane and the bulk black string or brane, the induced metric has an event horizon, so that the test brane contains a black hole. We call it a brane hole. When the test brane moves with a constant velocity V with respect to the bulk black object, it also has a brane hole, but its gravitational radius r e is greater than the size of the bulk black string or brane r 0 by the factor (1-V 2 ) -1 . We show that bulk ''photon'' emitted in the region between r 0 and r e can meet the test brane again at a point outside r e . From the point of view of observers on the test brane, the events of emission and capture of the bulk photon are connected by a spacelike curve in the induced geometry. This shows an example in which extra dimensions can be used to extract information from the interior of a lower-dimensional black object. Instead of the bulk black string or brane, one can also consider a bulk geometry without a horizon. We show that nevertheless the induced geometry on the moving test brane can include a brane hole. In such a case the extra dimensions can be used to extract information from the complete region of the brane-hole interior. We discuss thermodynamic properties of brane holes and interesting questions which arise when such an extra-dimensional channel for the information mining exists.

  1. Black hole astrophysics

    International Nuclear Information System (INIS)

    Blandford, R.D.; Thorne, K.S.

    1979-01-01

    Following an introductory section, the subject is discussed under the headings: on the character of research in black hole astrophysics; isolated holes produced by collapse of normal stars; black holes in binary systems; black holes in globular clusters; black holes in quasars and active galactic nuclei; primordial black holes; concluding remarks on the present state of research in black hole astrophysics. (U.K.)

  2. White holes and eternal black holes

    International Nuclear Information System (INIS)

    Hsu, Stephen D H

    2012-01-01

    We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi-thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal. (paper)

  3. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  4. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  5. Development of Compact, Modular Lunar Heat Flow Probes

    Science.gov (United States)

    Nagihara, S.; Zacny, K.; Hedlund, M.; Taylor, P. T.

    2014-01-01

    Geothermal heat flow measurements are a high priority for the future lunar geophysical network missions recommended by the latest Decadal Survey and previously the International Lunar Network. Because the lander for such a mission will be relatively small, the heat flow instrumentation must be a low-mass and low-power system. The instrument needs to measure both thermal gradient and thermal conductivity of the regolith penetrated. It also needs to be capable of excavating a deep enough hole (approx. 3 m) to avoid the effect of potential long-term changes of the surface thermal environment. The recently developed pneumatic excavation system can largely meet the low-power, low-mass, and the depth requirements. The system utilizes a stem which winds out of a pneumatically driven reel and pushes its conical tip into the regolith. Simultaneously, gas jets, emitted from the cone tip, loosen and blow away the soil. The thermal sensors consist of resistance temperature detectors (RTDs) embedded on the stem and an insitu thermal conductivity probe attached to the cone tip. The thermal conductivity probe consists of a short 'needle' (2.4-mm diam. and 15- to 20-mm length) that contains a platinum RTD wrapped in a coil of heater wire. During a deployment, when the penetrating cone reaches a desired depth, it stops blowing gas, and the stem pushes the needle into the yet-to-be excavated, undisturbed bottom soil. Then, it begins heating and monitors the temperature. Thermal conductivity of the soil can determined from the rate of temperature increase with time. When the measurement is complete, the system resumes excavation until it reaches the next targeted depth.

  6. Import-push or Export-pull?

    DEFF Research Database (Denmark)

    Jäkel, Ina Charlotte

    2014-01-01

    predictions regarding the export market and the role of product differentiation. Empirical results for a sample of Danish manufacturing industries confirm the import- "push" hypothesis as well as the export- "pull" hypothesis, but also reveal differences across industries. The selection effect of trade...... is mainly driven by the "import-push" if product differentiation is high, whereas it is driven by the "export-pull" if goods are homogeneous....

  7. Import-push or Export-pull?

    DEFF Research Database (Denmark)

    Jäkel, Ina Charlotte

    predictions regarding the export market and the role of product differentiation. Empirical results for a sample of Danish manufacturing industries confirm the import-"push" hypothesis as well as the export-"pull" hypothesis, but also reveal differences across industries. The selection effect of trade...... is mainly driven by the "import-push" if product differentiation is high, whereas it is driven by the "export-pull" if goods are homogeneous....

  8. Hidden conformal symmetry of extremal black holes

    International Nuclear Information System (INIS)

    Chen Bin; Long Jiang; Zhang Jiaju

    2010-01-01

    We study the hidden conformal symmetry of extremal black holes. We introduce a new set of conformal coordinates to write the SL(2,R) generators. We find that the Laplacian of the scalar field in many extremal black holes, including Kerr(-Newman), Reissner-Nordstrom, warped AdS 3 , and null warped black holes, could be written in terms of the SL(2,R) quadratic Casimir. This suggests that there exist dual conformal field theory (CFT) descriptions of these black holes. From the conformal coordinates, the temperatures of the dual CFTs could be read directly. For the extremal black hole, the Hawking temperature is vanishing. Correspondingly, only the left (right) temperature of the dual CFT is nonvanishing, and the excitations of the other sector are suppressed. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction.

  9. Hole superconductivity

    International Nuclear Information System (INIS)

    Hirsch, J.E.; Marsiglio, F.

    1989-01-01

    The authors review recent work on a mechanism proposed to explain high T c superconductivity in oxides as well as superconductivity of conventional materials. It is based on pairing of hole carriers through their direct Coulomb interaction, and gives rise to superconductivity because of the momentum dependence of the repulsive interaction in the solid state environment. In the regime of parameters appropriate for high T c oxides this mechanism leads to characteristic signatures that should be experimentally verifiable. In the regime of conventional superconductors most of these signatures become unobservable, but the characteristic dependence of T c on band filling survives. New features discussed her include the demonstration that superconductivity can result from repulsive interactions even if the gap function does not change sign and the inclusion of a self-energy correction to the hole propagator that reduces the range of band filling where T c is not zero

  10. Two-Man Bobsled Push Start Analysis

    Directory of Open Access Journals (Sweden)

    Lopes Alexandre Dias

    2016-04-01

    Full Text Available The importance of push start times on bobsled performance was evidenced by some studies, but at this moment there is no article to the authors’ knowledge that describes the bobsled push start. Thus, the objectives of this study were to describe the two-man bobsled push start, analyze the differences between teams, and estimate the most important variable analyzed. We hypothesized that the pilot and brakeman athletes’ movement patterns during a bobsled pushing start can be described. The images used in this study were obtained during the men’s two-man XIV World Championship of Bobsled (2004. Fifteen best teams participating in the championship were recorded, and four start runs for each team were analyzed. The videos were captured by two digital video cameras. The pilot athletes were analyzed during the moment that they touched the lateral push bar of the sled, and the brakemen were analyzed during the first take-off and first landing. The teams were pooled in three groups of five teams using the final ranking of pushing time. We concluded that there was a distinct pattern movement for pilots and brakemen. The initial position of the majority of the pilots was localized slightly behind the bar. After touching the lateral bar, the pilots remained in a semi-squat position, pushing the sled forward in a pattern of marching movement. All brakemen used the board attached to the track as a support for both feet at the start. The brakeman gave the greatest contribution to break the inertia of the sled. There was no significant difference of movement between the three groups analyzed for the pilot and the brakeman.

  11. 33 CFR 83.24 - Towing and pushing (Rule 24).

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Towing and pushing (Rule 24). 83... NAVIGATION RULES RULES Lights and Shapes § 83.24 Towing and pushing (Rule 24). (a) A power-driven vessel when... it can best be seen. (b) Pushing vessel and pushed vessel rigidly connected in composite unit. When a...

  12. Low-Back Biomechanics and Static Stability During Isometric Pushing

    Science.gov (United States)

    Granata, Kevin P.; Bennett, Bradford C.

    2006-01-01

    Pushing and pulling tasks are increasingly prevalent in industrial workplaces. Few studies have investigated low-back biomechanical risk factors associated with pushing, and we are aware of none that has quantified spinal stability during pushing exertions. Data recorded from 11 healthy participants performing isometric pushing exertions demonstrated that trunk posture, vector force direction of the applied load, and trunk moment were influenced (p pushing task, and foot position. A biomechanical model was used to analyze the posture and hand force data gathered from the pushing exertions. Model results indicate that pushing exertions provide significantly (p pushing exertions. If one maintains stability by means of cocontraction, additional spinal load is thereby created, increasing the risk of overload injury. Thus it is important to consider muscle cocontraction when evaluating the biomechanics of pushing exertions. Potential applications of this research include improved assessment of biomechanical risk factors for the design of industrial pushing tasks. PMID:16435695

  13. Effect of push handle height on net moments and forces on the musculoskeletal system during standardized wheelchair pushing tasks

    NARCIS (Netherlands)

    Van Der Woude, L H; Van Koningsbruggen, C M; Kroes, A L; Kingma, I

    1995-01-01

    The aim of this investigation was to analyze the external forces and biomechanical loading on the musculoskeletal system during wheelchair pushing, in relation to different push handle heights. In addition, recommendations for wheelchair pushing in accordance with push handle height are made. Eight

  14. The Uneven Legal Push for Europe

    DEFF Research Database (Denmark)

    Wind, Marlene; Martinsen, Dorte Sindbjerg; Rotger, Gabriel Pons

    2009-01-01

    National courts have been key players in the legal push for Europe, though notably to varying degrees. This paper examines the persisting variations in the referral rates of national courts and the underlying causal factors, aiming to better understand why some member states' courts have been more...... reluctant to join in the legal push for Europe. By using econometric methods, it challenges the modified neofunctionalist argument that the extent of intra-EC trade explains the referral practice of the individual member states. Majoritarian democracy is hypothesized as a causal factor in the low referral...... of majoritarian democracy on the number of referrals. The paper concludes that, owing to the uneven legal push for Europe, some member states and their citizens remain at arms' length from the legal integration process - and, in consequence, from the full impact of European integration....

  15. Developing technology pushed breakthroughs: an empirical study

    Directory of Open Access Journals (Sweden)

    Jari Sarja

    2017-12-01

    Full Text Available Developing a technology push product that brings real novelty to the market is difficult, risky and costly. This case study analyzes success factors defined by the literature. True industrial cases, representing Finnish ICT firms in their early phase after a successful market entry, were researched for the success factor analysis. The whole set of the previously introduced success factors were variably supported, and three new factors arose. Because the technology pushed development processes are risky with high failure rates, the validated success factors are valuable knowledge for the developments intensive firm’s management.

  16. Bumpy black holes from spontaneous Lorentz violation

    International Nuclear Information System (INIS)

    Dubovsky, Sergei; Tinyakov, Peter; Zaldarriaga, Matias

    2007-01-01

    We consider black holes in Lorentz violating theories of massive gravity. We argue that in these theories black hole solutions are no longer universal and exhibit a large number of hairs. If they exist, these hairs probe the singularity inside the black hole providing a window into quantum gravity. The existence of these hairs can be tested by future gravitational wave observatories. We generically expect that the effects we discuss will be larger for the more massive black holes. In the simplest models the strength of the hairs is controlled by the same parameter that sets the mass of the graviton (tensor modes). Then the upper limit on this mass coming from the inferred gravitational radiation emitted by binary pulsars implies that hairs are likely to be suppressed for almost the entire mass range of the super-massive black holes in the centers of galaxies

  17. Push Characteristics in Wheelchair Court Sport Sprinting

    NARCIS (Netherlands)

    van der Slikke, Rienk M A; Berger, Monique; Bregman, Daan; Veeger, Dirkjan

    2016-01-01

    Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own wheelchair

  18. Push characteristics in wheelchair court sport sprinting

    NARCIS (Netherlands)

    van der Slikke, R.M.A.; Berger, Monique; Bregman, D.J.J.; Veeger, H.E.J.; van der Helm, FCT; Jansen, AJ

    2016-01-01

    Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own

  19. The Transnational State and the Infrastructure Push

    DEFF Research Database (Denmark)

    Ougaard, Morten

    2018-01-01

    In 2010, the G20, in cooperation with major international organisations, launched a comprehensive effort – here labelled the infrastructure push – to promote infrastructure investments around the world. Using selected transnationalised elements from historical materialism, this is explained as a ....... In this cooperation, the international organisations have a relatively autonomous role in line with a historical materialist understanding of state apparatuses....

  20. The Transnational State and the Infrastructure Push

    DEFF Research Database (Denmark)

    Ougaard, Morten

    In 2010 the G20 in cooperation with major international organizations launched a comprehensive effort - here labelled the infrastructure push – to promote infrastructure investments around the world. Using selected transnationalised elements from historical materialism, this is explained as a tra....... In this cooperation, the international organizations have a relatively autonomous role in line with a historical materialist understanding of state apparatuses....

  1. Octopus movement: push right, go left.

    Science.gov (United States)

    Hooper, Scott L

    2015-05-04

    Octopus arms have essentially infinite degrees of freedom. New research shows that, despite this potentially great complexity, to locomote octopuses simply elongate one or more arms, thus pushing the body in the opposite direction, and do so without activating the arms in an ordered pattern. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Pushing the Limit: A Class Project

    Science.gov (United States)

    Odafe, Victor U.

    2012-01-01

    Instructors are constantly struggling to help students understand mathematical concepts as well as the relevance of mathematics to the real world. In calculus, students possess misconceptions of the limit concept. "Pushing the Limit" refers to a semester-long calculus class project that required students to read about, interview calculus…

  3. Black Hole Safari: Tracking Populations and Hunting Big Game

    Science.gov (United States)

    McConnell, N. J.

    2013-10-01

    Understanding the physical connection, or lack thereof, between the growth of galaxies and supermassive black holes is a key challenge in extragalactic astronomy. Dynamical studies of nearby galaxies are building a census of black hole masses across a broad range of galaxy types and uncovering statistical correlations between galaxy bulge properties and black hole masses. These local correlations provide a baseline for studying galaxies and black holes at higher redshifts. Recent measurements have probed the extremes of the supermassive black hole population and introduced surprises that challenge simple models of black hole and galaxy co-evolution. Future advances in the quality and quantity of dynamical black hole mass measurements will shed light upon the growth of massive galaxies and black holes in different cosmic environments.

  4. Pengaruh Latihan Traditional Push Up, Plyometric Push Up, dan Incline Push Up Terhadap Kekuatan Otot Lengan, Power Otot Lengan, dan Daya Tahan Otot Lengan

    Directory of Open Access Journals (Sweden)

    Febriyan Dwi Cahyono

    2018-05-01

    Full Text Available Tujuan penelitian ini adalah untuk peningkatan performa fisik otot lengan siswa ekstrakulikuler putra SMAN 2 Lamongan yang memiliki kelemahan saat dilakukan evaluasi fisik. Empat puluh siswa sehat dengan melihat status gizi melalui indeks masa tubuh (IMT dipilih sesuai dengan kriteria dan dilakukan pretest dan pemeringkatan sehingga masuk dalam pengelompokan traditional push up, plyometric push up, incline push up dan kelompok kontrol. Push up 30 detik, push up 60 detik dan medicine ball test digunakan untuk mengukur peningkatan kinerja. Ketiga kelompok berpartisipasi dalam penelitian tiga hari dalam seminggu selama enam minggu dan menyelesaikan 18 sesi pelatihan, pada frekuensi 3 sesi per minggu. Hasil uji paired sample t-test dalam kelompok traditional push up menunjukkan pengaruh yang signifikan pada variabel kekuatan dan daya tahan, kelompok plyometric push up menunjukkan pengaruh yang signifikan pada variabel kekuatan dan power, dan kelompok incline push up menunjukkan pengaruh yang signifikan pada variabel kekuatan dan daya tahan.  Disimpulkan dari penelitian ini bahwa pelatihan traditional push up, plyometric push up dan incline push up ketiganya efektif untuk peningkatan kinerja tubuh bagian atas.

  5. To push or not to push? Affective influences on moral judgment depend on decision frame.

    Science.gov (United States)

    Pastötter, Bernhard; Gleixner, Sabine; Neuhauser, Theresa; Bäuml, Karl-Heinz T

    2013-03-01

    People's moods can influence moral judgment. Such influences may arise because moods affect moral emotion, or because moods affect moral thought. The present study provides evidence that, at least in the footbridge dilemma, moods affect moral thought. The results of two experiments are reported in which, after induction of positive, negative, or neutral moods and presentation of the footbridge scenario, participants were asked one of two differentially framed closing questions. In the active frame, participants were asked whether they would be active and push the man, making thoughts about pushing accessible; in the passive frame, they were asked whether they would be passive and not push the man, making thoughts about not pushing accessible. The results show that affective influences on moral judgment depended on participants' decision frame. Compared to neutral moods, positive moods induced utilitarian responding - i.e., deciding to push - in the active decision frame, but induced nonutilitarian responding - i.e., deciding to not push - in the passive decision frame; in negative moods, exactly the opposite picture arose. The results suggest that people's moods affect moral judgment by conferring value on moral thought. Positive moods promote and negative moods inhibit accessible thoughts. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Water cooled static pressure probe

    Science.gov (United States)

    Lagen, Nicholas T. (Inventor); Eves, John W. (Inventor); Reece, Garland D. (Inventor); Geissinger, Steve L. (Inventor)

    1991-01-01

    An improved static pressure probe containing a water cooling mechanism is disclosed. This probe has a hollow interior containing a central coolant tube and multiple individual pressure measurement tubes connected to holes placed on the exterior. Coolant from the central tube symmetrically immerses the interior of the probe, allowing it to sustain high temperature (in the region of 2500 F) supersonic jet flow indefinitely, while still recording accurate pressure data. The coolant exits the probe body by way of a reservoir attached to the aft of the probe. The pressure measurement tubes are joined to a single, larger manifold in the reservoir. This manifold is attached to a pressure transducer that records the average static pressure.

  7. The Formation of Supermassive Black Holes in the First Galaxies

    NARCIS (Netherlands)

    Schleicher, Dominik R. G.; Banerjee, Robi; Sur, Sharanya; Glover, Simon C. O.; Spaans, Marco; Klessen, Ralf S.

    2010-01-01

    We discuss the formation of supermassive black holes in the early universe, and how to probe their subsequent evolution with the upcoming mm/sub-mm telescope ALMA. We first focus on the chemical and radiative conditions for black hole formation, in particular considering radiation trapping and

  8. The Formation of Supermassive Black Holes in the First Galaxies

    NARCIS (Netherlands)

    Schleicher, Dominik R. G.; Banerjee, Robi; Sur, Sharanya; Glover, Simon C. O.; Spaans, Marco; Klessen, Ralf S.

    We discuss the formation of supermassive black holes in the early universe, and how to probe their subsequent evolution with the upcoming mm/sub-mm telescope ALMA. We first focus on the chemical and radiative conditions for black hole formation, in particular considering radiation trapping and

  9. Push technology at Argonne National Laboratory.

    Energy Technology Data Exchange (ETDEWEB)

    Noel, R. E.; Woell, Y. N.

    1999-04-06

    Selective dissemination of information (SDI) services, also referred to as current awareness searches, are usually provided by periodically running computer programs (personal profiles) against a cumulative database or databases. This concept of pushing relevant content to users has long been integral to librarianship. Librarians traditionally turned to information companies to implement these searches for their users in business, academia, and the science community. This paper describes how a push technology was implemented on a large scale for scientists and engineers at Argonne National Laboratory, explains some of the challenges to designers/maintainers, and identifies the positive effects that SDI seems to be having on users. Argonne purchases the Institute for Scientific Information (ISI) Current Contents data (all subject areas except Humanities), and scientists no longer need to turn to outside companies for reliable SDI service. Argonne's database and its customized services are known as ACCESS (Argonne-University of Chicago Current Contents Electronic Search Service).

  10. Body pushing, prescription drugs and hospital admission.

    Science.gov (United States)

    Byard, Roger W; Kenneally, Michaela

    2017-09-01

    A 39-year-old man died of multi-organ failure complicating mixed drug toxicity that included methadone, oxazepam, oxycodone and nitrazepam. His past medical history involved alcohol and poly-substance abuse with chronic self-harm and suicidal ideation. There had been multiple hospital admissions for drug overdoses. At autopsy the most unusual finding was of two packages of 10 tablets each, wrapped in thin plastic film within the rectum. The insertion of drugs into body orifices and cavities has been termed body pushing to distinguish it from body packing where illicit drugs are wrapped and swallowed for transport and smuggling, and body stuffing where small amounts of loosely wrapped or unwrapped drugs are swallowed to conceal evidence from police. This case demonstrates that body pushing may not always involve illicit drugs or attempted concealment from police or customs officials. It appears that the drugs had been hidden to ensure an additional supply during the time of residence in hospital. The extent to which body pushing is currently being used by patients to smuggle drugs into secure medical facilities is yet to be determined.

  11. Report on ignitability testing of ''no-flow'' push bit

    International Nuclear Information System (INIS)

    Witwer, K.S.

    1997-01-01

    Testing was done to determine if an ignition occurs during a sixty foot drop of a Universal Sampler onto a push-mode bit in a flammable gas environment. Ten drops each of the sampler using both a push-mode and rotary mode insert onto a push-mode bit were completed. No ignition occurred during any of the drops

  12. 49 CFR 218.99 - Shoving or pushing movements.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Shoving or pushing movements. 218.99 Section 218... Derails § 218.99 Shoving or pushing movements. (a)(1) Each railroad shall adopt and comply with an... violated the requirements of this section. (2) The following requirements for shoving or pushing movements...

  13. 49 CFR 392.63 - Towing or pushing loaded buses.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Towing or pushing loaded buses. 392.63 Section 392... COMMERCIAL MOTOR VEHICLES Prohibited Practices § 392.63 Towing or pushing loaded buses. No disabled bus with... passengers aboard for the purpose of towing or pushing any disabled motor vehicle, except in such...

  14. Black holes. Chapter 6

    International Nuclear Information System (INIS)

    Penrose, R.

    1980-01-01

    Conditions for the formation of a black hole are considered, and the properties of black holes. The possibility of Cygnus X-1 as a black hole is discussed. Einstein's theory of general relativity in relation to the formation of black holes is discussed. (U.K.)

  15. Development of a direct push based in-situ thermal conductivity measurement system

    Science.gov (United States)

    Chirla, Marian Andrei; Vienken, Thomas; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Heat pump systems are commonly utilized in Europe, for the exploitation of the shallow geothermal potential. To guarantee a sustainable use of the geothermal heat pump systems by saving resources and minimizing potential negative impacts induced by temperature changes within soil and groundwater, new geothermal exploration methods and tools are required. The knowledge of the underground thermal properties is a necessity for a correct and optimum design of borehole heat exchangers. The most important parameter that indicates the performance of the systems is thermal conductivity of the ground. Mapping the spatial variability of thermal conductivity, with high resolution in the shallow subsurface for geothermal purposes, requires a high degree of technical effort to procure adequate samples for thermal analysis. A collection of such samples from the soil can disturb sample structure, so great care must be taken during collection to avoid this. Factors such as transportation and sample storage can also influence measurement results. The use of technologies like Thermal Response Test (TRT) require complex mechanical and electrical systems for convective heat transport in the subsurface and longer monitoring times, often three days. Finally, by using thermal response tests, often only one integral value is obtained for the entire coupled subsurface with the borehole heat exchanger. The common thermal conductivity measurement systems (thermal analyzers) can perform vertical thermal conductivity logs only with the aid of sample procurement, or by integration into a drilling system. However, thermal conductivity measurements using direct push with this type of probes are not possible, due to physical and mechanical limitations. Applying vertical forces using direct push technology, in order to penetrate the shallow subsurface, can damage the probe and the sensors systems. The aim of this study is to develop a new, robust thermal conductivity measurement probe, for direct

  16. Search for black holes

    International Nuclear Information System (INIS)

    Cherepashchuk, Anatolii M

    2003-01-01

    Methods and results of searching for stellar mass black holes in binary systems and for supermassive black holes in galactic nuclei of different types are described. As of now (June 2002), a total of 100 black hole candidates are known. All the necessary conditions Einstein's General Relativity imposes on the observational properties of black holes are satisfied for candidate objects available, thus further assuring the existence of black holes in the Universe. Prospects for obtaining sufficient criteria for reliably distinguishing candidate black holes from real black holes are discussed. (reviews of topical problems)

  17. Push Attack: Binding Virtual and Real Identities Using Mobile Push Notifications

    Directory of Open Access Journals (Sweden)

    Pierpaolo Loreti

    2018-01-01

    Full Text Available Popular mobile apps use push notifications extensively to offer an “always connected” experience to their users. Social networking apps use them as a real-time channel to notify users about new private messages or new social interactions (e.g., friendship request, tagging, etc.. Despite the cryptography used to protect these communication channels, the strict temporal binding between the actions that trigger the notifications and the reception of the notification messages in the mobile device may represent a privacy issue. In this work, we present the push notification attack designed to bind the physical owners of mobile devices with their virtual identities, even if pseudonyms are used. In an online attack, an active attacker triggers a push notification and captures the notification packets that transit in the network. In an offline attack, a passive attacker correlates the social network activity of a user with the received push notification. The push notification attack bypasses the standard ways of protecting user privacy based on the network layer by operating at the application level. It requires no additional software on the victim’s mobile device.

  18. Gedanken experiments on nearly extremal black holes and the third law

    International Nuclear Information System (INIS)

    Chirco, Goffredo; Liberati, Stefano; Sotiriou, Thomas P.

    2010-01-01

    A gedanken experiment in which a black hole is pushed to spin at its maximal rate by tossing into it a test body is considered. After demonstrating that this is kinematically possible for a test body made of reasonable matter, we focus on its implications for black hole thermodynamics and the apparent violation of the third law (unattainability of the extremal black hole). We argue that this is not an actual violation, due to subtleties in the absorption process of the test body by the black hole, which are not captured by the purely kinematic considerations.

  19. Skyrmion black hole hair: Conservation of baryon number by black holes and observable manifestations

    Energy Technology Data Exchange (ETDEWEB)

    Dvali, Gia [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, 80333 München (Germany); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Gußmann, Alexander, E-mail: alexander.gussmann@physik.uni-muenchen.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, 80333 München (Germany)

    2016-12-15

    We show that the existence of black holes with classical skyrmion hair invalidates standard proofs that global charges, such as the baryon number, cannot be conserved by a black hole. By carefully analyzing the standard arguments based on a Gedankenexperiment in which a black hole is seemingly-unable to return the baryon number that it swallowed, we identify inconsistencies in this reasoning, which does not take into the account neither the existence of skyrmion black holes nor the baryon/skyrmion correspondence. We then perform a refined Gedankenexperiment by incorporating the new knowledge and show that no contradiction with conservation of baryon number takes place at any stage of black hole evolution. Our analysis also indicates no conflict between semi-classical black holes and the existence of baryonic gauge interaction arbitrarily-weaker than gravity. Next, we study classical cross sections of a minimally-coupled massless probe scalar field scattered by a skyrmion black hole. We investigate how the skyrmion hair manifests itself by comparing this cross section with the analogous cross section caused by a Schwarzschild black hole which has the same ADM mass as the skyrmion black hole. Here we find an order-one difference in the positions of the characteristic peaks in the cross sections. The peaks are shifted to smaller scattering angles when the skyrmion hair is present. This comes from the fact that the skyrmion hair changes the near horizon geometry of the black hole when compared to a Schwarzschild black hole with same ADM mass. We keep the study of this second aspect general so that the qualitative results which we obtain can also be applied to black holes with classical hair of different kind.

  20. Scapular kinematics and muscle activities during pushing tasks.

    Science.gov (United States)

    Huang, Chun-Kai; Siu, Ka-Chun; Lien, Hen-Yu; Lee, Yun-Ju; Lin, Yang-Hua

    2013-01-01

    Pushing tasks are functional activities of daily living. However, shoulder complaints exist among workers exposed to regular pushing conditions. It is crucial to investigate the control of shoulder girdles during pushing tasks. The objective of the study was to demonstrate scapular muscle activities and motions on the dominant side during pushing tasks and the relationship between scapular kinematics and muscle activities in different pushing conditions. Thirty healthy adults were recruited to push a four-wheel cart in six pushing conditions. The electromyographic signals of the upper trapezius (UT) and serratus anterior (SA) muscles were recorded. A video-based system was used for measuring the movement of the shoulder girdle and scapular kinematics. Differences in scapular kinematics and muscle activities due to the effects of handle heights and weights of the cart were analyzed using two-way ANOVA with repeated measures. The relationships between scapular kinematics and muscle activities were examined by Pearson's correlation coefficients. The changes in upper trapezius and serratus anterior muscle activities increased significantly with increased pushing weights in the one-step pushing phase. The UT/SA ratio on the dominant side decreases significantly with increased handle heights in the one-step pushing phase. The changes in upward rotation, lateral slide and elevation of the scapula decreased with increased pushing loads in the trunk-forward pushing phase. This study indicated that increased pushing loads result in decreased motions of upward rotation, lateral slide and elevation of the scapula; decreased handle heights result in relatively increased activities of the serratus anterior muscles during pushing tasks.

  1. Delayed versus immediate pushing in second stage of labor.

    Science.gov (United States)

    Kelly, Mary; Johnson, Eileen; Lee, Vickie; Massey, Liz; Purser, Debbie; Ring, Karen; Sanderson, Stephanye; Styles, Juanita; Wood, Deb

    2010-01-01

    Comparison of two different methods for management of second stage of labor: immediate pushing at complete cervical dilation of 10 cm and delayed pushing 90 minutes after complete cervical dilation. This study was a randomized clinical trial in a labor and delivery unit of a not-for-profit community hospital. A sample of 44 nulliparous mothers with continuous epidural anesthesia were studied after random assignment to treatment groups. Subjects were managed with either immediate or delayed pushing during the second stage of labor at the time cervical dilation was complete. The primary outcome measure was the length of pushing during second stage of labor. Secondary outcomes included length of second stage of labor, maternal fatigue and perineal injuries, and fetal heart rate decelerations. Two-tailed, unpaired Student's t-tests and Chi-square analysis were used for data analysis. Level of significance was set at p pushing; N = 16 delayed pushing). The delayed pushing group had significantly shorter amount of time spent in pushing compared with the immediate pushing group (38.9 +/- 6.9 vs. 78.7 +/- 7.9 minutes, respectively, p = .002). Maternal fatigue scores, perineal injuries, and fetal heart rate decelerations were similar for both groups. Delaying pushing for up to 90 minutes after complete cervical dilation resulted in a significant decrease in the time mothers spent pushing without a significant increase in total time in second stage of labor.In clinical practice, healthcare providers sometimes resist delaying the onset of pushing after second stage of labor has begun because of a belief it will increase labor time. This study's finding of a 51% reduction in pushing time when mothers delay pushing for up to 90 minutes, with no significant increase in overall time for second stage of labor, disputes that concern.

  2. A Dancing Black Hole

    Science.gov (United States)

    Shoemaker, Deirdre; Smith, Kenneth; Schnetter, Erik; Fiske, David; Laguna, Pablo; Pullin, Jorge

    2002-04-01

    Recently, stationary black holes have been successfully simulated for up to times of approximately 600-1000M, where M is the mass of the black hole. Considering that the expected burst of gravitational radiation from a binary black hole merger would last approximately 200-500M, black hole codes are approaching the point where simulations of mergers may be feasible. We will present two types of simulations of single black holes obtained with a code based on the Baumgarte-Shapiro-Shibata-Nakamura formulation of the Einstein evolution equations. One type of simulations addresses the stability properties of stationary black hole evolutions. The second type of simulations demonstrates the ability of our code to move a black hole through the computational domain. This is accomplished by shifting the stationary black hole solution to a coordinate system in which the location of the black hole is time dependent.

  3. Pushing the Limits of Kinetic Arts: Strandbeests

    KAUST Repository

    Jansen, Theo

    2017-01-01

    In 1990, Dutch artist Theo Jansen introduced the world to his newest creation, the strandbeests. Kenetic sculptures created from plastic tubing, water bottles, and pipes, these beests survive on their own. These herds live on beaches all around the world, surviving on their waterfeelers and sandfeelers to remain safely on the sand. Powered by wind, these new life forms do not require food! Join us for a keynote lecture with Theo as he discusses the story behind the strandbeests as he pushes the limits with these beautiful and unique animals.

  4. Pushing the Limits of Kinetic Arts: Strandbeests

    KAUST Repository

    Jansen, Theo

    2017-01-12

    In 1990, Dutch artist Theo Jansen introduced the world to his newest creation, the strandbeests. Kenetic sculptures created from plastic tubing, water bottles, and pipes, these beests survive on their own. These herds live on beaches all around the world, surviving on their waterfeelers and sandfeelers to remain safely on the sand. Powered by wind, these new life forms do not require food! Join us for a keynote lecture with Theo as he discusses the story behind the strandbeests as he pushes the limits with these beautiful and unique animals.

  5. Characterization of Direct Push Vadose Zone Sediments from the 241-U Single-Shell Tank Farm

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Christopher F.; Valenta, Michelle M.; Serne, R. Jeffrey; Bjornstad, Bruce N.; Lanigan, David C.; Iovin, Cristian; Clayton, Ray E.; Geiszler, Keith N.; Clayton, Eric T.; Kutnyakov, Igor V.; Baum, Steven R.; Lindberg, Michael J.; Orr, Robert D.

    2007-12-20

    The overall goals of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., are 1) to define risks from past and future single-shell tank farm activities, 2) to identify and evaluate the efficacy of interim measures, and 3) to aid, via collection of geochemical information and data, the future decisions that must be made by the U.S. Department of Energy (DOE) regarding the near-term operations, future waste retrieval, and final closure activities for the single-shell tank Waste Management Areas (WMAs). For a more complete discussion of the goals of the Tank Farm Vadose Zone Project, see the overall work plan, Phase 1 RCRA Facility Investigation/Corrective Measures Study Work Plan for the Single-Shell Tank Waste Management Areas (DOE 1999). Specific details on the rationale for activities performed at WMA U are found in Crumpler (2003). To meet these goals, CH2M HILL Hanford Group, Inc., asked scientists from Pacific Northwest National Laboratory (PNNL) to perform detailed analyses of vadose zone sediment collected within the U Single-Shell Tank Farm. Specifically, this report contains all the geochemical and selected physical characterization data collected on vadose zone sediment recovered from ten direct push characterization holes emplaced to investigate vadose zone contamination associated with potential leaks within the 241-U Single-Shell Tank Farm. Specific tanks targeted during this characterization campaign included tanks 241-U-104/241-U-105, 241-U-110, and 241-U-112. Additionally, this report compiles data from direct push samples collected north of tank 241-U-201, as well as sediment collected from the background borehole (C3393). After evaluating all the characterization and analytical data, there is no question that the vadose zone in the vicinity of tanks 241-U-104 and 241-U-105 has been contaminated by tank-related waste. This observation is not new, as gamma logging of drywells in the area has identified uranium contamination at the

  6. Probe Storage

    NARCIS (Netherlands)

    Gemelli, Marcellino; Abelmann, Leon; Engelen, Johannes Bernardus Charles; Khatib, M.G.; Koelmans, W.W.; Zaboronski, Olog; Campardo, Giovanni; Tiziani, Federico; Laculo, Massimo

    2011-01-01

    This chapter gives an overview of probe-based data storage research over the last three decades, encompassing all aspects of a probe recording system. Following the division found in all mechanically addressed storage systems, the different subsystems (media, read/write heads, positioning, data

  7. Cultural probes

    DEFF Research Database (Denmark)

    Madsen, Jacob Østergaard

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  8. Characterization of Direct Push Vadose Zone Sediments from the T and TY Waste Management Areas

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Christopher F.; Valenta, Michelle M.; Serne, R. Jeffrey; Bjornstad, Bruce N.; Lanigan, David C.; Iovin, Cristian; Clayton, Ray E.; Geiszler, Keith N.; Clayton, Eric T.; Kutnyakov, Igor V.; Baum, Steven R.; Lindberg, Michael J.; Orr, Robert D.

    2007-06-08

    This report contains all the geochemical and selected physical characterization data collected on vadose zone sediment recovered from 5 direct push characterization holes emplaced to investigate vadose zone contamination associated with leaks from tanks 241-TY-105 (UPR-200-W-152) and 241-TY-106 (UPR-200-W-153). Tank 241-TY-105 is estimated to have leaked 35,000 gal of tributyl phosphate (TBP) waste from the uranium recovery process to the vadose zone in 1960. Tank 241-TY-106 is estimated to have leaked 20,000 gal of TBP-uranium recovery waste to the vadose zone in 1959. Although several drywells in the vicinity of tank 241-TY-106 contain measurable quantities of cesium-137 and/or cobalt-60, their relatively low concentrations indicate that the contaminant inventory in the vadose zone around tank 241-TY-106 is quite small. Additionally, this report contains all the geochemical and selected physical characterization data collected on vadose zone sediment recovered from 7 direct push characterization holes emplaced to investigate vadose zone contamination associated with an overfill event and leak from tank 241-T-101.

  9. Effect of push frequency on the economy of wheelchair racers.

    Science.gov (United States)

    Goosey, V L; Campbell, I G; Fowler, N E

    2000-01-01

    The aim of the study was to examine the effect of varying push frequency on pushing economy (oxygen uptake at a given speed). Eight male wheelchair racers completed a series of exercise bouts on a wheelchair ergometer (Bromking Turbo Trainer, Bromakin, UK) at 6.58 m x s(-1). Initially, subjects self-selected their freely chosen push frequency (FCF); this was followed by 4 random trials pushing at 60, 80, 120, and 140% of this FCF. Steady state VO2 was determined using Douglas bags, and heart rate was recorded by telemetry. After each condition, a small capillary blood sample was obtained and analyzed for blood lactate concentration (BLa) and a rating of perceived exertion (RPE) was recorded. At 6.58 m x s(-1) oxygen uptake, RPE, and gross mechanical efficiency were nonlinearly related to push frequency. Analysis of variance showed a significant effect (P push frequency had little effect on HR although BLa increased linearly and was higher at the 140% FCF condition compared with 60% FCF (P push frequency increased. The start angle and end angle of hand contact were similar for conditions, whereas the range of trunk motion decreased with push frequency (P push frequency had an effect on pushing economy, and that the athletes' FCF was the most economical.

  10. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    large values of Ф, black holes do form and for small values the scalar field ... on the near side of the ridge ultimately evolve to form black holes while those configu- ... The inset shows a bird's eye view looking down on the saddle point.

  11. Quantum toy model for black-hole backreaction

    International Nuclear Information System (INIS)

    Maia, Clovis; Schuetzhold, Ralf

    2007-01-01

    We propose a simple quantum field theoretical toy model for black-hole evaporation and study the backreaction of Hawking radiation onto the classical background. It turns out that the horizon is also ''pushed back'' in this situation (i.e., the interior region shrinks) though this backreaction is not caused by energy conservation but by momentum balance. The effective heat capacity and induced entropy variation can have both signs--depending on the parameters of the model

  12. Pushing Back against Push-In: ESOL Teacher Resistance and the Complexities of Coteaching

    Science.gov (United States)

    McClure, Greg; Cahnmann-Taylor, Melisa

    2010-01-01

    As U. S. school districts struggle to address persistent achievement gaps between increasing numbers of English language learners (ELLs) and their native-English-speaking counterparts, many districts are moving away from segregative models like pull-out to implement more collaborative approaches such as coteaching, or push-in. In contrast to…

  13. Black hole hair removal

    International Nuclear Information System (INIS)

    Banerjee, Nabamita; Mandal, Ipsita; Sen, Ashoke

    2009-01-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair - degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  14. Local Operators in the Eternal Black Hole.

    Science.gov (United States)

    Papadodimas, Kyriakos; Raju, Suvrat

    2015-11-20

    In the AdS/CFT correspondence, states obtained by Hamiltonian evolution of the thermofield doubled state are also dual to an eternal black-hole geometry, which is glued to the boundary with a time shift generated by a large diffeomorphism. We describe gauge-invariant relational observables that probe the black hole interior in these states and constrain their properties using effective field theory. By adapting recent versions of the information paradox we show that these observables are necessarily described by state-dependent bulk-boundary maps, which we construct explicitly.

  15. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-DomInguez, J C [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); Obregon, O [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); RamIrez, C [Facultad de Ciencias FIsico Matematicas, Universidad Autonoma de Puebla, PO Box 1364, 72000 Puebla (Mexico); Sabido, M [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico)

    2007-11-15

    We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole.

  16. Black holes without firewalls

    Science.gov (United States)

    Larjo, Klaus; Lowe, David A.; Thorlacius, Larus

    2013-05-01

    The postulates of black hole complementarity do not imply a firewall for infalling observers at a black hole horizon. The dynamics of the stretched horizon, that scrambles and reemits information, determines whether infalling observers experience anything out of the ordinary when entering a large black hole. In particular, there is no firewall if the stretched horizon degrees of freedom retain information for a time of the order of the black hole scrambling time.

  17. Black holes are hot

    International Nuclear Information System (INIS)

    Gibbons, G.

    1976-01-01

    Recent work, which has been investigating the use of the concept of entropy with respect to gravitating systems, black holes and the universe as a whole, is discussed. The resulting theory of black holes assigns a finite temperature to them -about 10 -7 K for ordinary black holes of stellar mass -which is in complete agreement with thermodynamical concepts. It is also shown that black holes must continuously emit particles just like ordinary bodies which have a certain temperature. (U.K.)

  18. Black hole based tests of general relativity

    International Nuclear Information System (INIS)

    Yagi, Kent; Stein, Leo C

    2016-01-01

    General relativity has passed all solar system experiments and neutron star based tests, such as binary pulsar observations, with flying colors. A more exotic arena for testing general relativity is in systems that contain one or more black holes. Black holes are the most compact objects in the Universe, providing probes of the strongest-possible gravitational fields. We are motivated to study strong-field gravity since many theories give large deviations from general relativity only at large field strengths, while recovering the weak-field behavior. In this article, we review how one can probe general relativity and various alternative theories of gravity by using electromagnetic waves from a black hole with an accretion disk, and gravitational waves from black hole binaries. We first review model-independent ways of testing gravity with electromagnetic/gravitational waves from a black hole system. We then focus on selected examples of theories that extend general relativity in rather simple ways. Some important characteristics of general relativity include (but are not limited to) (i) only tensor gravitational degrees of freedom, (ii) the graviton is massless, (iii) no quadratic or higher curvatures in the action, and (iv) the theory is four-dimensional. Altering a characteristic leads to a different extension of general relativity: (i) scalar–tensor theories, (ii) massive gravity theories, (iii) quadratic gravity, and (iv) theories with large extra dimensions. Within each theory, we describe black hole solutions, their properties, and current and projected constraints on each theory using black hole based tests of gravity. We close this review by listing some of the open problems in model-independent tests and within each specific theory. (paper)

  19. Monopole Black Hole Skyrmions

    OpenAIRE

    Moss, Ian G; Shiiki, N; Winstanley, E

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  20. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs.

  1. What is black hole?

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. What is black hole? Possible end phase of a star: A star is a massive, luminous ball of plasma having continuous nuclear burning. Star exhausts nuclear fuel →. White Dwarf, Neutron Star, Black Hole. Black hole's gravitational field is so powerful that even ...

  2. Push-Pull Laser-Atomic Oscillator

    International Nuclear Information System (INIS)

    Jau, Y.-Y.; Happer, W.

    2007-01-01

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the 'field-independent 0-0 frequency' of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs

  3. Black hole levitron

    International Nuclear Information System (INIS)

    Arsiwalla, Xerxes D.; Verlinde, Erik P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.'s multicenter supersymmetric black hole solutions provides a supergravity description of such backgrounds within which a black hole can be trapped within a confined volume. This construction is realized by solving for a levitating black hole over a magnetic dipole base. We comment on how such a construction is akin to a mechanical levitron.

  4. Mobile probes

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....

  5. Optical probe

    International Nuclear Information System (INIS)

    Denis, J.; Decaudin, J.M.

    1984-01-01

    The probe includes optical means of refractive index n, refracting an incident light beam from a medium with a refractive index n1>n and reflecting an incident light beam from a medium with a refractive index n2 [fr

  6. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  7. Hole history, rotary hole DC-3

    International Nuclear Information System (INIS)

    1977-10-01

    Purpose of hole DC-3 was to drill into the Umtanum basalt flow using both conventional rotary and core drilling methods. The borehole is to be utilized for geophysical logging, future hydrological testing, and the future installation of a borehole laboratory for long-term pressure, seismic, and moisture migration or accumulation recording in the Umtanum basalt flow in support of the Basalt Waste Isolation Program. Hole DC-3 is located east of the 200 West barricaded area on the Hanford reservation

  8. Matter-antimatter separation in the early universe by rotating black holes

    Science.gov (United States)

    Leahy, D. A.

    1981-01-01

    Consideration of the effect of rotating black holes evaporating early in the universe shows that they would have produced oppositely directed neutrino and antineutrino currents, which push matter and antimatter apart. This separation mechanism is, however, too feeble to account for a present baryon-to-photon ratio of 10 to the -9th, and has no significant observational consequences.

  9. Black and white holes

    International Nuclear Information System (INIS)

    Zeldovich, Ya.; Novikov, I.; Starobinskij, A.

    1978-01-01

    The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius Rsub(r). At t>>Rsub(r)/c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius. (J.B.)

  10. Black and white holes

    Energy Technology Data Exchange (ETDEWEB)

    Zeldovich, Ya; Novikov, I; Starobinskii, A

    1978-07-01

    The theory is explained of the origination of white holes as a dual phenomenon with regard to the formation of black holes. Theoretically it is possible to derive the white hole by changing the sign of time in solving the general theory of relativity equation implying the black hole. The white hole represents the amount of particles formed in the vicinity of a singularity. For a distant observer, matter composed of these particles expands and the outer boundaries of this matter approach from the inside the gravitational radius R/sub r/. At t>>R/sub r//c all radiation or expulsion of matter terminates. For the outside observer the white hole exists for an unlimited length of time. In fact, however, it acquires the properties of a black hole and all processes in it cease. The qualitative difference between a white hole and a black hole is in that a white hole is formed as the result of an inner quantum explosion from the singularity to the gravitational radius and not as the result of a gravitational collapse, i.e., the shrinkage of diluted matter towards the gravitational radius.

  11. Primary black holes

    International Nuclear Information System (INIS)

    Novikov, I.; Polnarev, A.

    1981-01-01

    Proves are searched for of the formation of the so-called primary black holes at the very origin of the universe. The black holes would weigh less than 10 13 kg. The formation of a primary black hole is conditional on strong fluctuations of the gravitational field corresponding roughly to a half of the fluctuation maximally permissible by the general relativity theory. Only big fluctuations of the gravitational field can overcome the forces of the hot gas pressure and compress the originally expanding matter into a black hole. Low-mass black holes have a temperature exceeding that of the black holes formed from stars. A quantum process of particle formation, the so-called evaporation takes place in the strong gravitational field of a black hole. The lower the mass of the black hole, the shorter the evaporation time. The analyses of processes taking place during the evaporation of low-mass primary black holes show that only a very small proportion of the total mass of the matter in the universe could turn into primary black holes. (M.D.)

  12. Kinematics of the field hockey penalty corner push-in.

    Science.gov (United States)

    Kerr, Rebecca; Ness, Kevin

    2006-01-01

    The aims of the study were to determine those variables that significantly affect push-in execution and thereby formulate coaching recommendations specific to the push-in. Two 50 Hz video cameras recorded transverse and longitudinal views of push-in trials performed by eight experienced and nine inexperienced male push-in performers. Video footage was digitized for data analysis of ball speed, stance width, drag distance, drag time, drag speed, centre of massy displacement and segment and stick displacements and velocities. Experienced push-in performers demonstrated a significantly greater (p push-in and a significantly faster ball speed than inexperienced performers. In addition, the experienced performers showed a significant positive correlation between ball speed and playing experience and tended to adopt a combination of simultaneous and sequential segment rotation to achieve accuracy and fast ball speed. The study yielded the following coaching recommendations for enhanced push-in performance: maximize drag distance by maximizing front foot-ball distance at the start of the push-in; use a combination of simultaneous and sequential segment rotations to optimise both accuracy and ball speed and maximize drag speed.

  13. Pushing and pulling in relation to musculoskeletal complaints

    NARCIS (Netherlands)

    Hoozemans, M. J M; Van Der Beek, Allard J.; Frings-Dresen, M. H. W.

    2000-01-01

    The first cross-sectional analyses are presented of a longitudinal study regarding the relationship between pushing and pulling and musculoskeletal disorders. Workers exposed to pushing and pulling and workers who had administrative tasks received a questionnaire. A significant association between

  14. DNA probes

    International Nuclear Information System (INIS)

    Castelino, J.

    1992-01-01

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with 32 P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism's genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens

  15. DNA probes

    Energy Technology Data Exchange (ETDEWEB)

    Castelino, J

    1993-12-31

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with {sup 32}P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism`s genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens 10 figs, 2 tabs

  16. Chandra Sees Remarkable Eclipse of Black Hole

    Science.gov (United States)

    2007-04-01

    Chandra X-ray Image of NGC 1365 "Thanks to this eclipse, we were able to probe much closer to the edge of this black hole than anyone has been able to before," said co-author Martin Elvis from CfA. "Material this close in will likely cross the event horizon and disappear from the universe in about a hundred years, a blink of an eye in cosmic terms." In addition to measuring the size of this disk of material, Risaliti and his colleagues were also able to estimate the location of the dense gas cloud that eclipsed the X-ray source and central black hole. The Chandra data show that this cloud is one hundredth of a light year from the black hole's event horizon, or 300 times closer than generally thought. "AGN include the brightest objects in the Universe and are powerful probes of the early universe. So, it's vital to understand their basic structure," said Risaliti. "It turns out that we still have work to do to understand these monsters." A series of six Chandra observations of NGC 1365 were made every two days over a period of two weeks in April 2006. During five of the observations, high energy X-rays from the central X-ray source were visible, but in the second one - corresponding to the eclipse - they were not. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center, Cambridge, Mass. Additional information and images are available at: http://chandra.harvard.edu and http://chandra.nasa.gov

  17. Tracer gas evaluations of push-pull ventilation system performance.

    Science.gov (United States)

    Ojima, Jun

    2009-01-01

    A push-pull ventilation system is effective for hazardous material exhaustion. Although a push-pull ventilation system has advantages over a local exhaust hood, some laborious adjustments are required. The pertinence of the adjustments is uncertain because it is difficult to evaluate the performance of a push-pull ventilation system quantitatively. In this study, a measurement of the capture efficiency of a push-pull ventilation system was carried out by means of a tracer gas method. The capture efficiency decreased to 39.3-78.5% when blockage material, a dummy worker and a cross draft, were set in the ventilation zone, but the efficiency was 95.1-97.9% when the cross draft was stopped. The results suggest that the uniform flow of a push-pull ventilation system will detour a blockage and the performance of the system will not be reduced unless a cross draft disturbs the uniform flow.

  18. Pushing, pulling and manoeuvring an industrial cart: a psychophysiological study.

    Science.gov (United States)

    Giagloglou, Evanthia; Radenkovic, Milan; Brankovic, Sasa; Antoniou, Panagiotis; Zivanovic-Macuzic, Ivana

    2017-09-18

    One of the most frequent manual occupational tasks involves the pushing and pulling of a cart. Although several studies have associated health risks with pushing and pulling, the effects are not clear since occupational tasks have social, cognitive and physical components. The present work investigates a real case of a pushing and pulling occupational task from a manufacturing company. The study initially characterizes the case in accordance with Standard No. ISO 11228-2:2007 as low risk. An experiment with 14 individuals during three modalities of pushing and pulling was performed in order to further investigate the task with the application of electrophysiology. At the end, a simple questionnaire was given. The results show electrophysiological differences among the three modalities of pushing and pulling, with a major difference between action with no load and fully loaded with a full range of motions on the cart to handle.

  19. Young entrepreneurs pushed by necessity and pulled by opportunity

    DEFF Research Database (Denmark)

    Cheraghi, Maryam

    2017-01-01

    The vocational choice to be an entrepreneur is made in a social context of institutions in society, which channel, regulate, enable and constrain life, with pushes and pulls. The necessity to make a living may push the entrepreneur, or an opportunity for business may pull the entrepreneur to start....... The push by necessity and pull by opportunity are exerted by institutions in society such as its economy and culture. The purpose here is to account for how young entrepreneurs' experiences of opportunity-pull and necessity-push are influenced by society's economic wealth and culture, as traditional versus...... secular-rational culture and as survival versus self-expression culture. - A sample of 41,281 young entrepreneurs in 93 countries was surveyed in Global Entrepreneurship Monitor. - Analyses show that young entrepreneurs' experience of opportunity-pull rather than necessity-push is not distinctly...

  20. [Development of Biliary Contrast Agents Remote Pushing Device].

    Science.gov (United States)

    Zhu, Haoyang; Dong, Dinghui; Luo, Yu; Ren, Fenggang; Zhang, Jing; Tan, Wenjun; Shi, Aihua; Hu, Liangshuo; Wu, Rongqian; Lyu, Yi

    2018-01-30

    A biliary contrast agents pushing device, including a syringe pushing system and a remote controller is introduced. The syringe pushing system comprises an injector card slot, a support platform and an injection bolus fader. A 20 mL syringe can be fitted on the syringe pushing system and kept with the ground about 30 degree. This system can perform air bubble pumping back and contrast agents bolus injection as well as speed adjustment. Remote controller is an infrared remote control which can start and stop the syringe pushing system. With this device, the remote controlled cholangiography technology can be achieved, which can not only protect doctors from X-ray radiation but also improve the traditional T-tube cholangiography and the contrast effect, reduce postoperative complications in patients as well. The application of this device will improve the current diagnosis and treatment system, the device will benefit the majority of doctors and patients.

  1. Cosmological Probes for Supersymmetry

    Directory of Open Access Journals (Sweden)

    Maxim Khlopov

    2015-05-01

    Full Text Available The multi-parameter character of supersymmetric dark-matter models implies the combination of their experimental studies with astrophysical and cosmological probes. The physics of the early Universe provides nontrivial effects of non-equilibrium particles and primordial cosmological structures. Primordial black holes (PBHs are a profound signature of such structures that may arise as a cosmological consequence of supersymmetric (SUSY models. SUSY-based mechanisms of baryosynthesis can lead to the possibility of antimatter domains in a baryon asymmetric Universe. In the context of cosmoparticle physics, which studies the fundamental relationship of the micro- and macro-worlds, the development of SUSY illustrates the main principles of this approach, as the physical basis of the modern cosmology provides cross-disciplinary tests in physical and astronomical studies.

  2. Subsea prizes : companies pushing the envelope offshore

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, R.

    2009-06-15

    In order to make projects economic, companies are going farther offshore and deeper to find oil and gas or to use existing offshore platforms and longer horizontals. Companies such as StatoilHydro are reworking strategies on how to approach future oil finds. This article discussed examples of ultra deep and long horizontal oil finds such as Statoil's complicated but highly successful Gulltopp project. Although drilling ultra-deep wells or long horizontal wells is risky, they can also be very lucrative. The article also discussed McMoRan Exploration Company of New Orleans' high-risk deeper targets in the Gulf of Mexico and its exploration strategy. The longest well in the world, drilled by Maersk Oil Qatar AS was also described. The article noted that the Danish company reported that the entire horizontal section of the well was placed within a reservoir target which was only 20 feet thick. Schlumberger helped Maersk Oil Qatar break several records with extended reach drilling (ERD) offshore well. This well set 10 records, including the longest well ever drilled; longest along-hole departure; longest 8 and a half inch section; highest ERD ratio; highest directional drilling difficulty index; deepest directional control; deepest downlink, MWD transmission and LWD geosteering; deepest battery-less operation; longest reservoir contact; and longest open hole. Last, the article discussed an unsuccessful well drilled by Murphy Oil Corporation known as the Manhattan well. 8 figs.

  3. Association of the Duration of Active Pushing With Obstetric Outcomes.

    Science.gov (United States)

    Grobman, William A; Bailit, Jennifer; Lai, Yinglei; Reddy, Uma M; Wapner, Ronald J; Varner, Michael W; Caritis, Steve N; Prasad, Mona; Tita, Alan T N; Saade, George; Sorokin, Yoram; Rouse, Dwight J; Blackwell, Sean C; Tolosa, Jorge E

    2016-04-01

    To estimate the associations between the duration of active pushing during the second stage of labor and maternal and neonatal outcomes. We performed an observational study in which data were obtained by trained abstractors from maternal and neonatal charts of deliveries at 25 hospitals over a 3-year period. In this secondary analysis, women with no prior cesarean delivery who had a term, singleton, cephalic gestation and reached complete dilation were analyzed. The duration of pushing, defined as the time from initiation of pushing to either vaginal delivery or the decision to proceed with a cesarean delivery, was determined. The primary maternal outcome was cesarean delivery and the primary neonatal outcome was a composite that included: mechanical ventilation, proven sepsis, brachial plexus palsy, clavicular fracture, skull fracture, other fracture, seizures, hypoxic-ischemic encephalopathy, or death. Nulliparous and parous women were analyzed separately in univariable and then multivariable analyses. A total of 53,285 women were analyzed. In both nulliparous and parous women, longer duration of pushing was associated with increased odds of both cesarean delivery and the neonatal adverse outcome composite. Nevertheless, even after 4 hours of pushing, approximately 78% of nulliparous women who continued with active pushing had a vaginal delivery and more than 97% did not have the composite adverse neonatal outcome. Similarly, after more than 2 hours of pushing, approximately 82% of parous women who continued active pushing delivered vaginally and more than 97% did not have the adverse neonatal outcome. A longer duration of pushing is associated with an increased relative risk, but small absolute difference in risk, of neonatal complications. Approximately 78% of nulliparous women delivered vaginally even after 4 hours of pushing.

  4. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  5. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  6. Concerning production and decay of mini black holes

    CERN Document Server

    Hajdukovic, D

    2007-01-01

    In the next few years, theories predicting possibility to create mini black holes will be tested at CERN. Either experimental verification or rejection of these theories is of great scientific importance. There is a large consensus that, if successfully created, these short living mini black holes will decay through thermal (Hawking's) radiation. In the present comment we point out, that under assumption of the gravitational repulsion between matter and antimatter (in short we call it antigravity), thermal radiation may be dominated by a non-thermal radiation (being the consequence of pair creation from the vacuum, by gravitational field, which in the case of antigravity, pushes particles and antiparticles in opposite directions). Thus, the eventual creation of mini black holes may turn to be an unexpected opportunity to test the existence of antigravity.

  7. Accreting Black Holes

    OpenAIRE

    Begelman, Mitchell C.

    2014-01-01

    I outline the theory of accretion onto black holes, and its application to observed phenomena such as X-ray binaries, active galactic nuclei, tidal disruption events, and gamma-ray bursts. The dynamics as well as radiative signatures of black hole accretion depend on interactions between the relatively simple black-hole spacetime and complex radiation, plasma and magnetohydrodynamical processes in the surrounding gas. I will show how transient accretion processes could provide clues to these ...

  8. Nonextremal stringy black hole

    International Nuclear Information System (INIS)

    Suzuki, K.

    1997-01-01

    We construct a four-dimensional BPS saturated heterotic string solution from the Taub-NUT solution. It is a nonextremal black hole solution since its Euler number is nonzero. We evaluate its black hole entropy semiclassically. We discuss the relation between the black hole entropy and the degeneracy of string states. The entropy of our string solution can be understood as the microscopic entropy which counts the elementary string states without any complications. copyright 1997 The American Physical Society

  9. Naked black holes

    International Nuclear Information System (INIS)

    Horowitz, G.T.; Ross, S.F.

    1997-01-01

    It is shown that there are large static black holes for which all curvature invariants are small near the event horizon, yet any object which falls in experiences enormous tidal forces outside the horizon. These black holes are charged and near extremality, and exist in a wide class of theories including string theory. The implications for cosmic censorship and the black hole information puzzle are discussed. copyright 1997 The American Physical Society

  10. The limits to biocatalysis: pushing the envelope.

    Science.gov (United States)

    Sheldon, Roger A; Brady, Dean

    2018-06-12

    In the period 1985 to 1995 applications of biocatalysis, driven by the need for more sustainable manufacture of chemicals and catalytic, (enantio)selective methods for the synthesis of pharmaceutical intermediates, largely involved the available hydrolases. This was followed, in the next two decades, by revolutionary developments in protein engineering and directed evolution for the optimisation of enzyme function and performance that totally changed the biocatalysis landscape. In the same period, metabolic engineering and synthetic biology revolutionised the use of whole cell biocatalysis in the synthesis of commodity chemicals by fermentation. In particular, developments in the enzymatic enantioselective synthesis of chiral alcohols and amines are highlighted. Progress in enzyme immobilisation facilitated applications under harsh industrial conditions, such as in organic solvents. The emergence of biocatalytic or chemoenzymatic cascade processes, often with co-immobilised enzymes, has enabled telescoping of multi-step processes. Discovering and inventing new biocatalytic processes, based on (meta)genomic sequencing, evolving enzyme promiscuity, chemomimetic biocatalysis, artificial metalloenzymes, and the introduction of non-canonical amino acids into proteins, are pushing back the limits of biocatalysis function. Finally, the integral role of biocatalysis in developing a biobased carbon-neutral economy is discussed.

  11. Reconstructing the massive black hole cosmic history through gravitational waves

    International Nuclear Information System (INIS)

    Sesana, Alberto; Gair, Jonathan; Berti, Emanuele; Volonteri, Marta

    2011-01-01

    The massive black holes we observe in galaxies today are the natural end-product of a complex evolutionary path, in which black holes seeded in proto-galaxies at high redshift grow through cosmic history via a sequence of mergers and accretion episodes. Electromagnetic observations probe a small subset of the population of massive black holes (namely, those that are active or those that are very close to us), but planned space-based gravitational wave observatories such as the Laser Interferometer Space Antenna (LISA) can measure the parameters of 'electromagnetically invisible' massive black holes out to high redshift. In this paper we introduce a Bayesian framework to analyze the information that can be gathered from a set of such measurements. Our goal is to connect a set of massive black hole binary merger observations to the underlying model of massive black hole formation. In other words, given a set of observed massive black hole coalescences, we assess what information can be extracted about the underlying massive black hole population model. For concreteness we consider ten specific models of massive black hole formation, chosen to probe four important (and largely unconstrained) aspects of the input physics used in structure formation simulations: seed formation, metallicity ''feedback'', accretion efficiency and accretion geometry. For the first time we allow for the possibility of 'model mixing', by drawing the observed population from some combination of the 'pure' models that have been simulated. A Bayesian analysis allows us to recover a posterior probability distribution for the ''mixing parameters'' that characterize the fractions of each model represented in the observed distribution. Our work shows that LISA has enormous potential to probe the underlying physics of structure formation.

  12. Probe specificity

    International Nuclear Information System (INIS)

    Laget, J.M.

    1986-11-01

    Specificity and complementarity of hadron and electron probes must be systematically developed to answer three questions currently asked in intermediate energy nuclear physics: what is nucleus structure at short distances, what is nature of short range correlations, what is three body force nature [fr

  13. Post-Kerr black hole spectroscopy

    Science.gov (United States)

    Glampedakis, Kostas; Pappas, George; Silva, Hector O.; Berti, Emanuele

    2017-09-01

    One of the central goals of the newborn field of gravitational wave astronomy is to test gravity in the highly nonlinear, strong field regime characterizing the spacetime of black holes. In particular, "black hole spectroscopy" (the observation and identification of black hole quasinormal mode frequencies in the gravitational wave signal) is expected to become one of the main tools for probing the structure and dynamics of Kerr black holes. In this paper we take a significant step toward that goal by constructing a "post-Kerr" quasinormal mode formalism. The formalism incorporates a parametrized but general perturbative deviation from the Kerr metric and exploits the well-established connection between the properties of the spacetime's circular null geodesics and the fundamental quasinormal mode to provide approximate, eikonal limit formulas for the modes' complex frequencies. The resulting algebraic toolkit can be used in waveform templates for ringing black holes with the purpose of measuring deviations from the Kerr metric. As a first illustrative application of our framework, we consider the Johannsen-Psaltis deformed Kerr metric and compute the resulting deviation in the quasinormal mode frequency relative to the known Kerr result.

  14. Downhole instrument including a flexible probe which can travel freely around bends in a borehole

    International Nuclear Information System (INIS)

    Dickinson III, B. W. O.

    1985-01-01

    Bore hole instrument and methods of manufacturing and using the same. The instrument includes an elongated flexible probe which is inserted into a bore hole and can travel freely around bends of relatively short radius in the hole. The probe includes a plurality of sensors, explosive charges or the like which are spaced apart and embedded in a flexible body comprising a mass of cushioning material, with a flexible outer casing of fabric having a high tensile strength. The probe is driven into a bore hole in piston-like fashion, and the flexible body enables the probe to travel freely around bends of relatively short radius. Instrumentation for processing signals from the probe is located at the surface of the earth, and a flexible cable interconnects the instrumentation with the probe

  15. Ground reaction force characteristics of Tai Chi push hand.

    Science.gov (United States)

    Chang, Yao-Ting; Chang, Jia-Hao; Huang, Chen-Fu

    2014-01-01

    Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s(-1)) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant's body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.

  16. Fuzzy Based PC-PUSH in CR-MANETs

    Directory of Open Access Journals (Sweden)

    S. Nejatian

    2014-01-01

    Full Text Available In cognitive radio (CR, the secondary user (SU needs to hand off its ongoing communication to an idle channel in order to avoid interference to the primary user (PU. Spectrum hand off issue becomes challenging in CR mobile ad hoc networks (CR-MANETs because of the uncertainty in spectrum availability, broad range of spectrum bands and lack of central entity. The purpose of this study is to design a unified spectrum handoff (USH scheme for CR-MANETs that considers the spectrum heterogeneity and its availability over time and space. A local flow hand off is performed when spectrum hand off cannot be carried out due to the SUs mobility. To improve further USH, preemptive unified spectrum handoff (PUSH algorithm is proposed in which two different preemptive hand off threshold regions are defined. The PUSH algorithm also predicts the cognitive link availability considering the PU interference boundary. Although the PUSH scheme improves the hand off performance, the number of spectrum hand offs due to the PU activity should be reduced in this scheme. Therefore, the PC-PUSH (Power Controller-PUSH scheme is proposed in which the fuzzy logic is used to improve the PUSH in terms of the number of spectrum handoffs because of the PU activity. The PC-PUSH decreases the interference to the PUs, while reducing the number of spectrum handoffs. The results show that the proposed scheme improves the link maintenance probability, decreases the hand off delay, and reduces the number of spectrum handoffs.

  17. Prone positioning reduces severe pushing behavior: three case studies.

    Science.gov (United States)

    Fujino, Yuji; Amimoto, Kazu; Sugimoto, Satoshi; Fukata, Kazuhiro; Inoue, Masahide; Takahashi, Hidetoshi; Makita, Shigeru

    2016-09-01

    [Purpose] Pushing behavior is classically described as a disorder of body orientation in the coronal plane. Most interventions for pushing behavior have focused on correcting the deviation in vertical perception. However, pushing behavior seems to involve erroneous movements associated with excessive motor output by the non-paretic limbs and trunk. The present study aimed to inhibit muscular hyper-activity by placing the non-paretic limbs and trunk in the prone position. [Subjects and Methods] The subjects of the present study were 3 acute stroke patients with severe pushing behavior. The study consisted of the following 3 phases: baseline, intervention, and follow-up. In addition to conventional therapy, patients received relaxation therapy in the prone position for 10 minutes a day over 2 days. The severity of pushing behavior was assessed using the scale for contraversive pushing, and truncal balance was evaluated using the trunk control test. These assessments were performed before and after the baseline phase, and after the intervention and follow-up phases. [Results] At the baseline phase, both scores were poor. Both scores improved after the intervention and follow-up phases, and all the patients could sit independently. [Conclusion] Relaxation therapy in the prone position might ameliorate pushing behavior and impaired truncal balance.

  18. Plasma dynamics near critical density inferred from direct measurements of laser hole boring

    Science.gov (United States)

    Gong, Chao; Tochitsky, Sergei Ya.; Fiuza, Frederico; Pigeon, Jeremy J.; Joshi, Chan

    2016-06-01

    We have used multiframe picosecond optical interferometry to make direct measurements of the hole boring velocity, vHB, of the density cavity pushed forward by a train of C O2 laser pulses in a near critical density helium plasma. As the pulse train intensity rises, the increasing radiation pressure of each pulse pushes the density cavity forward and the plasma electrons are strongly heated. After the peak laser intensity, the plasma pressure exerted by the heated electrons strongly impedes the hole boring process and the vHB falls rapidly as the laser pulse intensity falls at the back of the laser pulse train. A heuristic theory is presented that allows the estimation of the plasma electron temperature from the measurements of the hole boring velocity. The measured values of vHB, and the estimated values of the heated electron temperature as a function of laser intensity are in reasonable agreement with those obtained from two-dimensional numerical simulations.

  19. Black hole Berry phase

    NARCIS (Netherlands)

    de Boer, J.; Papadodimas, K.; Verlinde, E.

    2009-01-01

    Supersymmetric black holes are characterized by a large number of degenerate ground states. We argue that these black holes, like other quantum mechanical systems with such a degeneracy, are subject to a phenomenon which is called the geometric or Berry’s phase: under adiabatic variations of the

  20. Black holes are warm

    International Nuclear Information System (INIS)

    Ravndal, F.

    1978-01-01

    Applying Einstein's theory of gravitation to black holes and their interactions with their surroundings leads to the conclusion that the sum of the surface areas of several black holes can never become less. This is shown to be analogous to entropy in thermodynamics, and the term entropy is also thus applied to black holes. Continuing, expressions are found for the temperature of a black hole and its luminosity. Thermal radiation is shown to lead to explosion of the black hole. Numerical examples are discussed involving the temperature, the mass, the luminosity and the lifetime of black mini-holes. It is pointed out that no explosions corresponding to the prediction have been observed. It is also shown that the principle of conservation of leptons and baryons is broken by hot black holes, but that this need not be a problem. The related concept of instantons is cited. It is thought that understanding of thermal radiation from black holes may be important for the development of a quantified gravitation theory. (JIW)

  1. Black holes matter

    DEFF Research Database (Denmark)

    Kragh, Helge Stjernholm

    2016-01-01

    Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015).......Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015)....

  2. Quantum black holes

    OpenAIRE

    Hooft, G. 't

    1987-01-01

    This article is divided into three parts. First, a systematic derivation of the Hawking radiation is given in three different ways. The information loss problem is then discussed in great detail. The last part contains a concise discussion of black hole thermodynamics. This article was published as chapter $6$ of the IOP book "Lectures on General Relativity, Cosmology and Quantum Black Holes" (July $2017$).

  3. Black hole levitron

    NARCIS (Netherlands)

    Arsiwalla, X.D.; Verlinde, E.P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.’s multicenter

  4. Newborn Black Holes

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Scientists using NASA's Swift satellite say they have found newborn black holes, just seconds old, in a confused state of existence. The holes are consuming material falling into them while somehow propelling other material away at great speeds. "First comes a blast of gamma rays followed by intense pulses of x-rays. The energies involved are much…

  5. Lifshitz topological black holes

    International Nuclear Information System (INIS)

    Mann, R.B.

    2009-01-01

    I find a class of black hole solutions to a (3+1) dimensional theory gravity coupled to abelian gauge fields with negative cosmological constant that has been proposed as the dual theory to a Lifshitz theory describing critical phenomena in (2+1) dimensions. These black holes are all asymptotic to a Lifshitz fixed point geometry and depend on a single parameter that determines both their area (or size) and their charge. Most of the solutions are obtained numerically, but an exact solution is also obtained for a particular value of this parameter. The thermodynamic behaviour of large black holes is almost the same regardless of genus, but differs considerably for small black holes. Screening behaviour is exhibited in the dual theory for any genus, but the critical length at which it sets in is genus-dependent for small black holes.

  6. The Astrophysics of Merging Black Holes

    Science.gov (United States)

    Schnittman, Jeremy D.

    2011-01-01

    When two supermassive black holes (SMBHs) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  7. Synthesizing a novel genetic sequential logic circuit: a push-on push-off switch.

    Science.gov (United States)

    Lou, Chunbo; Liu, Xili; Ni, Ming; Huang, Yiqi; Huang, Qiushi; Huang, Longwen; Jiang, Lingli; Lu, Dan; Wang, Mingcong; Liu, Chang; Chen, Daizhuo; Chen, Chongyi; Chen, Xiaoyue; Yang, Le; Ma, Haisu; Chen, Jianguo; Ouyang, Qi

    2010-01-01

    Design and synthesis of basic functional circuits are the fundamental tasks of synthetic biologists. Before it is possible to engineer higher-order genetic networks that can perform complex functions, a toolkit of basic devices must be developed. Among those devices, sequential logic circuits are expected to be the foundation of the genetic information-processing systems. In this study, we report the design and construction of a genetic sequential logic circuit in Escherichia coli. It can generate different outputs in response to the same input signal on the basis of its internal state, and 'memorize' the output. The circuit is composed of two parts: (1) a bistable switch memory module and (2) a double-repressed promoter NOR gate module. The two modules were individually rationally designed, and they were coupled together by fine-tuning the interconnecting parts through directed evolution. After fine-tuning, the circuit could be repeatedly, alternatively triggered by the same input signal; it functions as a push-on push-off switch.

  8. Black holes in the gravity/gauge theory correspondence

    International Nuclear Information System (INIS)

    Gregory, J.P.

    2002-06-01

    The AdS/CFT correspondence provides a microscopic description of black hole thermodynamics. In this thesis, I study the relation between the classical physics of black holes and this microscopic description. I first consider the gauge theory's holographic encoding of non-trivial global causal structure, by studying various probes of the black hole. I study the charged black hole, so that the thermal scale is separated from the horizon scale, to demonstrate which relates to the field theory scale size. I find that, when probing the horizon, both Wilson loops and the duals of static supergravity probes have a scale size determined by the horizon, but the field theory scale size is divergent for a time-dependent probe. I also use the bulk black hole geometry to study the physics of the boundary theory. If we consider a dynamical boundary, a braneworld cosmology is induced from the bulk. However, the presence of matter on the brane introduces unconventional quadratic terms in the FRW equations of this braneworld. I find that bulk black holes induce identical unconventional terms on a matterless brane, therefore providing an alternative description of the same cosmology. A new conjecture relating classical and thermodynamic stability of black branes has emerged from the AdS/CFT correspondence. I make progress in proving this for the case of Schwarzschild black holes in a finite cavity. I also extend the conjecture to the supergravity backgrounds of the direct product form Schwarzschild-AdS x Sphere, which are relevant to my study of the AdS/CFT correspondence. (author)

  9. Soft robot design methodology for `push-button' manufacturing

    Science.gov (United States)

    Paik, Jamie

    2018-06-01

    `Push-button' or fully automated manufacturing would enable the production of robots with zero intervention from human hands. Realizing this utopia requires a fundamental shift from a sequential (design-materials-manufacturing) to a concurrent design methodology.

  10. La Push, Washington Tsunami Forecast Grids for MOST Model

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The La Push, Washington Forecast Model Grids provides bathymetric data strictly for tsunami inundation modeling with the Method of Splitting Tsunami (MOST) model....

  11. Pushed news: when the news comes to the cellphone

    Directory of Open Access Journals (Sweden)

    Antonio Fidalgo

    2009-12-01

    Full Text Available Combining two findings of recent surveys on the Internet which state that 1 “the Internet will soon surpass all other media as a main source for national and international news” and 2 “the mobile device will be the primary connection tool to the Internet in 2020” leads us to the conclusion that smartphones will soon be the primary source for news access. But if so, how will news come to the Internetconnected cellphones? In accordance with the distinction, already drawn in 1997, between push and pull technologies as two different forms of how content is delivered to the end users, cellphones are characterized as push devices (passive reception, in opposition to computers, classified as pull devices (active reception. The news items that fit cellphones are pushed news. And they will be pushed as SMS, e-mails, tweets and through news aggregators.

  12. PUSHED NEWS: When the news comes to the cellphone

    Directory of Open Access Journals (Sweden)

    Antonio Fidalgo

    2009-12-01

    Full Text Available Combining two findings of recent surveys on the Internet whichstate that 1 “the Internet will soon surpass all other media as a main source for national and international news” and 2 “the mobile device will be the primary connection tool to the Internet in 2020” leads us to the conclusion that smartphones will soon be the primary source for news access. But if so, how will news come to the Internetconnected cellphones? In accordance with the distinction, already drawn in 1997, between push and pull technologies as two different forms of how content is delivered to the end users, cellphones are characterized as push devices (passive reception, in opposition to computers, classified as pull devices (active reception. The news items that fit cellphones are pushed news. And they will be pushed as SMS, e-mails, tweets and through news aggregators.

  13. Modeling Atom Probe Tomography: A review

    Energy Technology Data Exchange (ETDEWEB)

    Vurpillot, F., E-mail: francois.vurpillot@univ-rouen.fr [Groupe de Physique des Matériaux, UMR CNRS 6634, Université de Rouen, Saint Etienne du Rouvray 76801 (France); Oberdorfer, C. [Institut für Materialwissenschaft, Lehrstuhl für Materialphysik, Universität Stuttgart, Heisenbergstr. 3, 70569 Stuttgart (Germany)

    2015-12-15

    Improving both the precision and the accuracy of Atom Probe Tomography reconstruction requires a correct understanding of the imaging process. In this aim, numerical modeling approaches have been developed for 15 years. The injected ingredients of these modeling tools are related to the basic physic of the field evaporation mechanism. The interplay between the sample nature and structure of the analyzed sample and the reconstructed image artefacts have pushed to gradually improve and make the model more and more sophisticated. This paper reviews the evolution of the modeling approach in Atom Probe Tomography and presents some future potential directions in order to improve the method. - Highlights: • The basics of field evaporation. • The main aspects of Atom Probe Tomography modeling. • The intrinsic limitations of the current method and future potential directions to improve the understanding of tip to image ion projection.

  14. Structural Change Out of Agriculture: Labor Push versus Labor Pull

    OpenAIRE

    Francisco Alvarez-Cuadrado; Markus Poschke

    2011-01-01

    The process of economic development is characterized by substantial rural-urban migrations and a decreasing share of agriculture in output and employment. The literature highlights two main engines behind this process of structural change: (i) improvements in agricultural technology combined with the effect of Engel's law of demand push resources out of the agricultural sector (the "labor push" hypothesis), and (ii) improvements in industrial technology attract labor into this sector (the "la...

  15. Push and pull strategies: applications for health care marketing.

    Science.gov (United States)

    Kingsley, B R

    1987-08-01

    As health care markets mature and expand, strategies available in other industries become useful. This article examines how traditional push-pull strategies apply to health care. Marketers using a push strategy recognize that the sale of their services or goods is dependent upon the endorsement of a middleman and promote their product through the middleman. Those using a pull strategy market directly to the consumer. In this article, the author outlines the advantages and disadvantages of using each strategy.

  16. Entropy of quasiblack holes

    International Nuclear Information System (INIS)

    Lemos, Jose P. S.; Zaslavskii, Oleg B.

    2010-01-01

    We trace the origin of the black hole entropy S, replacing a black hole by a quasiblack hole. Let the boundary of a static body approach its own gravitational radius, in such a way that a quasihorizon forms. We show that if the body is thermal with the temperature taking the Hawking value at the quasihorizon limit, it follows, in the nonextremal case, from the first law of thermodynamics that the entropy approaches the Bekenstein-Hawking value S=A/4. In this setup, the key role is played by the surface stresses on the quasihorizon and one finds that the entropy comes from the quasihorizon surface. Any distribution of matter inside the surface leads to the same universal value for the entropy in the quasihorizon limit. This can be of some help in the understanding of black hole entropy. Other similarities between black holes and quasiblack holes such as the mass formulas for both objects had been found previously. We also discuss the entropy for extremal quasiblack holes, a more subtle issue.

  17. ULTRAMASSIVE BLACK HOLE COALESCENCE

    International Nuclear Information System (INIS)

    Khan, Fazeel Mahmood; Holley-Bockelmann, Kelly; Berczik, Peter

    2015-01-01

    Although supermassive black holes (SMBHs) correlate well with their host galaxies, there is an emerging view that outliers exist. Henize 2-10, NGC 4889, and NGC 1277 are examples of SMBHs at least an order of magnitude more massive than their host galaxy suggests. The dynamical effects of such ultramassive central black holes is unclear. Here, we perform direct N-body simulations of mergers of galactic nuclei where one black hole is ultramassive to study the evolution of the remnant and the black hole dynamics in this extreme regime. We find that the merger remnant is axisymmetric near the center, while near the large SMBH influence radius, the galaxy is triaxial. The SMBH separation shrinks rapidly due to dynamical friction, and quickly forms a binary black hole; if we scale our model to the most massive estimate for the NGC 1277 black hole, for example, the timescale for the SMBH separation to shrink from nearly a kiloparsec to less than a parsec is roughly 10 Myr. By the time the SMBHs form a hard binary, gravitational wave emission dominates, and the black holes coalesce in a mere few Myr. Curiously, these extremely massive binaries appear to nearly bypass the three-body scattering evolutionary phase. Our study suggests that in this extreme case, SMBH coalescence is governed by dynamical friction followed nearly directly by gravitational wave emission, resulting in a rapid and efficient SMBH coalescence timescale. We discuss the implications for gravitational wave event rates and hypervelocity star production

  18. Shoulder joint loading and posture during medicine cart pushing task.

    Science.gov (United States)

    Xu, Xu; Lin, Jia-Hua; Boyer, Jon

    2013-01-01

    Excessive physical loads and awkward shoulder postures during pushing and pulling are risk factors for shoulder pain. Pushing a medicine cart is a major component of a work shift for nurses and medical assistants in hospitals and other health care facilities. A laboratory experiment was conducted to examine the effects of common factors (e.g., lane congestion, cart load stability, floor surface friction) on shoulder joint moment and shoulder elevation angle of participants during cart pushing. Participants pushed a medicine cart on straight tracks and turning around right-angle corners. Peak shoulder joint moments reached 25.1 Nm, 20.3 Nm, and 26.8 Nm for initial, transition, and turning phases of the pushing tasks, indicating that shoulder joint loading while pushing a medical cart is comparable to levels previously reported from heavy manual activities encountered in industry (e.g., garbage collection). Also, except for user experience, all other main study factors, including congestion level, cart load stability, location of transition strip, shoulder tendency, surface friction, and handedness, significantly influenced shoulder joint moment and shoulder elevation angle. The findings provide a better understanding of shoulder exposures associated with medicine cart operations and may be helpful in designing and optimizing the physical environment where medicine carts are used.

  19. Effects of Black Hole Spin on the Limit-Cycle Behaviour of Accretion ...

    Indian Academy of Sciences (India)

    We present a spatially 1.5-dimensional, time-dependent numerical study of accretion disks around Kerr black holes. Our study focuses on the limit-cycle behavior of thermally unstable accretion disks. We find that maximal luminosity may be a more appropriate probe of black hole spin than the cycle duration and influence ...

  20. Black holes new horizons

    CERN Document Server

    Hayward, Sean Alan

    2013-01-01

    Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h

  1. New aspect of critical nonlinearly charged black hole

    Science.gov (United States)

    Hendi, S. H.; Taghadomi, Z. S.; Corda, C.

    2018-04-01

    The motion of a point charged particle moving in the background of the critical power Maxwell charged AdS black holes in a probe approximation is studied. The extended phase space, where the cosmological constant appears as a pressure, is regarded and the effective potential is investigated. At last, the mass-to-charge ratio and the large q limit are studied.

  2. Black holes with halos

    Science.gov (United States)

    Monten, Ruben; Toldo, Chiara

    2018-02-01

    We present new AdS4 black hole solutions in N =2 gauged supergravity coupled to vector and hypermultiplets. We focus on a particular consistent truncation of M-theory on the homogeneous Sasaki–Einstein seven-manifold M 111, characterized by the presence of one Betti vector multiplet. We numerically construct static and spherically symmetric black holes with electric and magnetic charges, corresponding to M2 and M5 branes wrapping non-contractible cycles of the internal manifold. The novel feature characterizing these nonzero temperature configurations is the presence of a massive vector field halo. Moreover, we verify the first law of black hole mechanics and we study the thermodynamics in the canonical ensemble. We analyze the behavior of the massive vector field condensate across the small-large black hole phase transition and we interpret the process in the dual field theory.

  3. Introducing the Black Hole

    Science.gov (United States)

    Ruffini, Remo; Wheeler, John A.

    1971-01-01

    discusses the cosmology theory of a black hole, a region where an object loses its identity, but mass, charge, and momentum are conserved. Include are three possible formation processes, theorized properties, and three way they might eventually be detected. (DS)

  4. Do Hypervolumes Have Holes?

    Science.gov (United States)

    Blonder, Benjamin

    2016-04-01

    Hypervolumes are used widely to conceptualize niches and trait distributions for both species and communities. Some hypervolumes are expected to be convex, with boundaries defined by only upper and lower limits (e.g., fundamental niches), while others are expected to be maximal, with boundaries defined by the limits of available space (e.g., potential niches). However, observed hypervolumes (e.g., realized niches) could also have holes, defined as unoccupied hyperspace representing deviations from these expectations that may indicate unconsidered ecological or evolutionary processes. Detecting holes in more than two dimensions has to date not been possible. I develop a mathematical approach, implemented in the hypervolume R package, to infer holes in large and high-dimensional data sets. As a demonstration analysis, I assess evidence for vacant niches in a Galapagos finch community on Isabela Island. These mathematical concepts and software tools for detecting holes provide approaches for addressing contemporary research questions across ecology and evolutionary biology.

  5. Colliding black hole solution

    International Nuclear Information System (INIS)

    Ahmed, Mainuddin

    2005-01-01

    A new solution of Einstein equation in general relativity is found. This solution solves an outstanding problem of thermodynamics and black hole physics. Also this work appears to conclude the interpretation of NUT spacetime. (author)

  6. Black-hole thermodynamics

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1980-01-01

    Including black holes in the scheme of thermodynamics has disclosed a deep-seated connection between gravitation, heat and the quantum that may lead us to a synthesis of the corresponding branches of physics

  7. Cosmology with coalescing massive black holes

    International Nuclear Information System (INIS)

    Hughes, Scott A; Holz, Daniel E

    2003-01-01

    The gravitational waves generated in the coalescence of massive binary black holes will be measurable by LISA to enormous distances. Redshifts z ∼ 10 or larger (depending somewhat on the mass of the binary) can potentially be probed by such measurements, suggesting that binary coalescences can be made into cosmological tools. We discuss two particularly interesting types of probe. First, by combining gravitational-wave measurements with information about the cosmography of the universe, we can study the evolution of black-hole masses and merger rates as a function of redshift, providing information about the growth of structures at high redshift and possibly constraining hierarchical merger scenarios. Second, if it is possible to associate an 'electromagnetic' counterpart with a coalescence, it may be possible to measure both redshift and luminosity distance to an event with less than ∼1% error. Such a measurement would constitute an amazingly precise cosmological standard candle. Unfortunately, gravitational lensing uncertainties will reduce the quality of this candle significantly. Though not as amazing as might have been hoped, such a candle would nonetheless very usefully complement other distance-redshift probes, in particular providing a valuable check on systematic effects in such measurements

  8. White dwarfs - black holes

    International Nuclear Information System (INIS)

    Sexl, R.; Sexl, H.

    1975-01-01

    The physical arguments and problems of relativistic astrophysics are presented in a correct way, but without any higher mathematics. The book is addressed to teachers, experimental physicists, and others with a basic knowledge covering an introductory lecture in physics. The issues dealt with are: fundamentals of general relativity, classical tests of general relativity, curved space-time, stars and planets, pulsars, gravitational collapse and black holes, the search for black holes, gravitational waves, cosmology, cosmogony, and the early universe. (BJ/AK) [de

  9. Magnonic black holes

    OpenAIRE

    Roldán-Molina, A.; Nunez, A.S.; Duine, R. A.

    2017-01-01

    We show that the interaction between spin-polarized current and magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons - the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the imp...

  10. Supersymmetric black holes

    OpenAIRE

    de Wit, Bernard

    2005-01-01

    The effective action of $N=2$, $d=4$ supergravity is shown to acquire no quantum corrections in background metrics admitting super-covariantly constant spinors. In particular, these metrics include the Robinson-Bertotti metric (product of two 2-dimensional spaces of constant curvature) with all 8 supersymmetries unbroken. Another example is a set of arbitrary number of extreme Reissner-Nordstr\\"om black holes. These black holes break 4 of 8 supersymmetries, leaving the other 4 unbroken. We ha...

  11. Black Holes and Thermodynamics

    OpenAIRE

    Wald, Robert M.

    1997-01-01

    We review the remarkable relationship between the laws of black hole mechanics and the ordinary laws of thermodynamics. It is emphasized that - in analogy with the laws of thermodynamics - the validity the laws of black hole mechanics does not appear to depend upon the details of the underlying dynamical theory (i.e., upon the particular field equations of general relativity). It also is emphasized that a number of unresolved issues arise in ``ordinary thermodynamics'' in the context of gener...

  12. How well can ultracompact bodies imitate black hole ringdowns?

    Science.gov (United States)

    Glampedakis, Kostas; Pappas, George

    2018-02-01

    The ongoing observations of merging black holes by the instruments of the fledging gravitational wave astronomy has opened the way for testing the general-relativistic Kerr black hole metric and, at the same time, for probing the existence of more speculative horizonless ultracompact objects. In this paper we quantify the difference that these two classes of objects may exhibit in the post-merger ringdown signal. By considering rotating systems in general relativity and assuming an eikonal limit and a third-order Hartle-Thorne slow-rotation approximation, we provide the first calculation of the early ringdown frequency and damping time as a function of the body's multipolar structure. Using the example of a gravastar, we show that the main ringdown signal may differ by as much as a few percent with respect to that of a Kerr black hole, a deviation that could be probed by near-future Advanced LIGO/Virgo searches.

  13. Electron holes observed in the Moon Plasma Wake

    Science.gov (United States)

    Hutchinson, I. H.; Malaspina, D.; Zhou, C.

    2017-10-01

    Electrostatic instabilities are predicted in the magnetized wake of plasma flowing past a non-magnetic absorbing object such as a probe or the moon. Analysis of the data from the Artemis satellites, now orbiting the moon at distances ten moon radii and less, shows very clear evidence of fast-moving isolated solitary potential structures causing bipolar electric field excursions as they pass the satellite's probes. These structures have all the hallmarks of electron holes: BGK solitons typically a few Debye-lengths in size, self-sustaining by a deficit of phase-space density on trapped orbits. Electron holes are now observed to be widespread in space plasmas. They have been observed in PIC simulations of the moon wake to be the non-linear consequence of the predicted electron instabilities. Simulations document hole prevalence, speed, length, and depth; and theory can explain many of these features from kinetic analysis. The solar wind wake is certainly the cause of the overwhelming majority of the holes observed by Artemis, because we observe almost all holes to be in or very near to the wake. We compare theory and simulation of the hole generation, lifetime, and transport mechanisms with observations. Work partially supported by NASA Grant NNX16AG82G.

  14. A sled push stimulus potentiates subsequent 20-m sprint performance.

    Science.gov (United States)

    Seitz, Laurent B; Mina, Minas A; Haff, G Gregory

    2017-08-01

    The objective of this study was to examine the potentiating effects of performing a single sprint-style sled push on subsequent unresisted 20m sprint performance. Randomized crossover design. Following a familiarization session, twenty rugby league players performed maximal unresisted 20m sprints before and 15s, 4, 8 and 12min after a single sled push stimulus loaded with either 75 or 125% body mass. The two sled push conditions were performed in a randomized order over a one-week period. The fastest sprint time recorded before each sled push was compared to that recorded at each time point after to determine the post-activation potentiation (PAP) effect. After the 75% body mass sled push, sprint time was 0.26±1.03% slower at the 15s time point (effect size [ES]=0.07) but faster at the 4 (-0.95±2.00%; ES=-0.22), 8 (-1.80±1.43%; ES=-0.42) and 12 (-1.54±1.54%; ES=-0.36)min time points. Sprint time was slower at all the time points after the 125% body mass sled (1.36±2.36%-2.59±2.90%; ESs=0.34-0.64). Twenty-meter sprint performance is potentiated 4-12min following a sled push loaded with 75% body mass while it is impaired after a 125% body mass sled. These results are of great importance for coaches seeking to potentiate sprint performance with the sled push exercise. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  15. Black holes from large N singlet models

    Science.gov (United States)

    Amado, Irene; Sundborg, Bo; Thorlacius, Larus; Wintergerst, Nico

    2018-03-01

    The emergent nature of spacetime geometry and black holes can be directly probed in simple holographic duals of higher spin gravity and tensionless string theory. To this end, we study time dependent thermal correlation functions of gauge invariant observables in suitably chosen free large N gauge theories. At low temperature and on short time scales the correlation functions encode propagation through an approximate AdS spacetime while interesting departures emerge at high temperature and on longer time scales. This includes the existence of evanescent modes and the exponential decay of time dependent boundary correlations, both of which are well known indicators of bulk black holes in AdS/CFT. In addition, a new time scale emerges after which the correlation functions return to a bulk thermal AdS form up to an overall temperature dependent normalization. A corresponding length scale was seen in equal time correlation functions in the same models in our earlier work.

  16. D0-branes in black hole attractors

    International Nuclear Information System (INIS)

    Gaiotto, Davide; Simons, Aaron; Strominger, Andrew; Yin Xi

    2006-01-01

    Configurations of N probe D0-branes in a Calabi-Yau black hole are studied. A large degeneracy of near-horizon bound states are found which can be described as lowest Landau levels tiling the horizon of the black hole. These states preserve some of the enhanced supersymmetry of the near-horizon AdS 2 x S 2 x CY 3 attractor geometry, but not of the full asymptotically flat solution. Supersymmetric non-abelian configurations are constructed which, via the Myers effect, develop charges associated with higher-dimensional branes wrapping CY 3 cycles. An SU(1,1/2) superconformal quantum mechanics describing D0-branes in the attractor geometry is explicitly constructed

  17. 33 CFR 164.76 - Towline and terminal gear for towing alongside and pushing ahead.

    Science.gov (United States)

    2010-07-01

    ... towing alongside and pushing ahead. 164.76 Section 164.76 Navigation and Navigable Waters COAST GUARD... Towline and terminal gear for towing alongside and pushing ahead. The owner, master, or operator of each vessel towing alongside or pushing ahead shall ensure that the face wires, spring lines, and push gear...

  18. KOMPARASI SISTEM MANUFAKTUR PUSH DAN PULL MELALUI PENDEKATAN SIMULASI

    Directory of Open Access Journals (Sweden)

    Eric Wibisono

    2004-01-01

    Full Text Available Manufacturing systems that are often classified as push and pull often invite question: "How far do the differences between those two systems exist?" Many researches have been carried out but succinct answer to the above question is always difficult to reach. The difficulty roots from the variety of definition of the push and pull systems itself and also from the variety of complexity of a manufacturing system. This paper attempts to study the differences in performance between push and pull systems in a relatively simple model that consists of 4 serial processors with buffers located between these processors. Variations being modelled is on the setting of the system's load (high and low and the buffer size with performance being measured include machine utilization, number of outputs and mean flow time of jobs. The approach used is simulation using ProModel software as the tool. From the experiments it can be derived that buffer size turns out to be a very critical factor in system performance. Moreover, it is also proved that when the buffer size is large, push and pull systems do not differ significantly. Abstract in Bahasa Indonesia : Sistem manufaktur yang umumnya dikategorikan menjadi sistem push dan pull sering mengundang pertanyaan: "Seberapa jauh perbedaan dari kedua sistem tersebut ada?" Banyak penelitian telah dilakukan namun jawaban yang lugas atas pertanyaan tersebut sulit diperoleh. Kesulitan ini umumnya berakar dari beragamnya definisi sistem push dan pull itu sendiri serta variasi dari kompleksitas suatu sistem manufaktur. Makalah ini mencoba melihat perbedaan antara kinerja sistem push dan pull dalam suatu model sederhana yang terdiri dari 4 prosesor serial dengan buffer yang diletakkan di antara masing-masing prosesor tersebut. Variasi yang dilakukan adalah pada setting beban kerja sistem (padat dan ringan dan ukuran buffer dengan kinerja yang diukur adalah utilisasi mesin, jumlah output dan rata-rata waktu tinggal job

  19. INTERSESSION RELIABILITY OF UPPER EXTREMITY ISOKINETIC PUSH-PULL TESTING.

    Science.gov (United States)

    Riemann, Bryan L; Davis, Sarah E; Huet, Kevin; Davies, George J

    2016-02-01

    Based on the frequency pushing and pulling patterns are used in functional activities, there is a need to establish an objective method of quantifying the muscle performance characteristics associated with these motions, particularly during the later stages of rehabilitation as criteria for discharge. While isokinetic assessment offers an approach to quantifying muscle performance, little is known about closed kinetic chain (CKC) isokinetic testing of the upper extremity (UE). To determine the intersession reliability of isokinetic upper extremity measurement of pushing and pulling peak force and average power at slow (0.24 m/s), medium (0.43 m/s) and fast (0.61 m/s) velocities in healthy young adults. The secondary purpose was to compare pushing and pulling peak force (PF) and average power (AP) between the upper extremity limbs (dominant, non-dominant) across the three velocities. Twenty-four physically active men and women completed a test-retest (>96 hours) protocol in order to establish isokinetic UE CKC reliability of PF and AP during five maximal push and pull repetitions at three velocities. Both limb and speed orders were randomized between subjects. High test-retest relative reliability using intraclass correlation coefficients (ICC2, 1) were revealed for PF (.91-.97) and AP (.85-.95) across velocities, limbs and directions. PF typical error (% coefficient of variation) ranged from 6.1% to 11.3% while AP ranged from 9.9% to 26.7%. PF decreased significantly (p pushing were significantly greater than pulling at all velocities, however the push-pull differences in PF became less as velocity increased. There were no significant differences identified between the dominant and nondominant limbs. Isokinetically derived UE CKC push-pull PF and AP are reliable measures. The lack of limb differences in healthy normal participants suggests that clinicians can consider bilateral comparisons when interpreting test performance. The increase in pushing PF and

  20. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

  1. Effects of Angle Variations in Suspension Push-up Exercise.

    Science.gov (United States)

    Gulmez, Irfan

    2017-04-01

    Gulmez, I. Effects of angle variations in suspension push-up exercise. J Strength Cond Res 31(4): 1017-1023, 2017-This study aimed to determine and compare the amount of loads on the TRX Suspension Trainer (TRX) straps and ground reaction forces at 4 different angles during TRX push-ups. Twenty-eight male (mean age, 24.1 ± 2.9 years; height, 179.4 ± 8.0 m; weight, 78.8 ± 9.8 kg) physical education and sports university students participated in this study. The subjects were tested at TRX angles (0, 15, 30, 45°) during the TRX push-ups. Force data were recorded by a force platform and load cells integrated into the TRX straps. The results show that as the TRX angle was reduced, the load applied to the TRX straps increased and simultaneously the load measured by the force platform decreased. This was true for both the elbow joint changing from flexion to extension and vice versa. When the TRX angle was set at 0° and subjects' elbows were at extension during TRX push-up, 50.4% of the subjects' body weight, and when the elbows were at flexion, 75.3% of the body weight was registered by the sensors on the TRX straps. The results of this study can be used in the calculation of the training load and volume (resistance training programming) during TRX push-up exercises at varying angles.

  2. Effect of different pushing speeds on bench press.

    Science.gov (United States)

    Padulo, J; Mignogna, P; Mignardi, S; Tonni, F; D'Ottavio, S

    2012-05-01

    The purpose of this study was to investigate the effect on muscular strength after a 3-week training with the bench-press at a fixed pushing of 80-100% maximal speed (FPS) and self-selected pushing speed (SPS). 20 resistance-trained subjects were divided at random in 2 groups differing only regarding the pushing speed: in the FPS group (n=10) it was equal to 80-100% of the maximal speed while in the SPS group (n=10) the pushing speed was self-selected. Both groups were trained twice a week for 3 weeks with a load equal to 85% of 1RM and monitored with the encoder. Before and after the training we measured pushing speed and maximum load. Significant differences between and within the 2 groups were pointed out using a 2-way ANOVA for repeated measures. After 3 weeks a significant improvement was shown especially in the FPS group: the maximum load improved by 10.20% and the maximal speed by 2.22%, while in the SPS group the effect was <1%. This study shows that a high velocity training is required to increase the muscle strength further in subjects with a long training experience and this is possible by measuring the individual performance speed for each load. © Georg Thieme Verlag KG Stuttgart · New York.

  3. [Length of pushing efforts: pushing is not playing. Reply to the article of C. Le Ray and F. Audibert].

    Science.gov (United States)

    Schaal, J-P; Dreyfus, M; Bretelle, F; Carbonne, B; Dupuis, O; Foulhy, C; Goffinet, F; Houfflin-Debarge, V; Langer, B; Martin, A; Mercier, C; Mignon, A; Poulain, P; Simon, A; Teurnier, F; Verspyck, E; Riethmuller, D; Hoffmann, P; Pierre, F

    2008-11-01

    The aim of this work is to answer constructively to C. Le Ray and F. Audibert who were surprised that the French guidelines recommended an assisted delivery after 30 min pushing, even if the fetal heart rate is reassuring. We first resumed the definition of "second stage of labor", this word including the first phase with no pushing efforts and the second phase with active pushing of the mother. With that definition, the length of the second stage is around 60 min for the primipara and 20 min for the multipara, this length being modified by the use of peridural. We then specified the physiological mechanisms influencing the acidobasic equilibrium during the pushing time. Those mechanisms are difficult to consider because foetal heart rate monitoring is often "lost" during that phase. Altogether, these factors bring incertitude about progressive foetal acidosis and incapacity to diagnose it. Finally, the literature analysis teaches us that increasing the second stage of labor (inactive plus active phases) during the normal pregnancy seems to be at low risk for the foetus within the primiparas, but display a risk for the mother and so might be limited. Comparing the delayed pushing with the immediate pushing only lead us to conclude that delayed pushing is dangerous, as is prolonged second stage. In conclusion, we think that prolonging the second stage of labor is possible but must be by increasing the inactive first phase of the second stage, especially as long as we will not get a noninvasive and reliable method allowing assessing the well-being of the foetus.

  4. Stroller running: Energetic and kinematic changes across pushing methods.

    Science.gov (United States)

    Alcantara, Ryan S; Wall-Scheffler, Cara M

    2017-01-01

    Running with a stroller provides an opportunity for parents to exercise near their child and counteract health declines experienced during early parenthood. Understanding biomechanical and physiological changes that occur when stroller running is needed to evaluate its health impact, yet the effects of stroller running have not been clearly presented. Here, three commonly used stroller pushing methods were investigated to detect potential changes in energetic cost and lower-limb kinematics. Sixteen individuals (M/F: 10/6) ran at self-selected speeds for 800m under three stroller conditions (2-Hands, 1-Hand, and Push/Chase) and an independent running control. A significant decrease in speed (p = 0.001) and stride length (ppushing method had a significant effect on speed (p = 0.001) and stride length (ppushing technique influences stroller running speed and kinematics. These findings suggest specific fitness effects may be achieved through the implementation of different pushing methods.

  5. Probing black hole accretion in quasar pairs at high redshift

    Science.gov (United States)

    Vignali, C.; Piconcelli, E.; Perna, M.; Hennawi, J.; Gilli, R.; Comastri, A.; Zamorani, G.; Dotti, M.; Mathur, S.

    2018-06-01

    Models and observations suggest that luminous quasar activity is triggered by mergers, so it should preferentially occur in the most massive primordial dark matter haloes, where the frequency of mergers is expected to be the highest. Since the importance of galaxy mergers increases with redshift, we identify the high-redshift Universe as the ideal laboratory for studying dual AGN. Here, we present the X-ray properties of two systems of dual quasars at z = 3.0-3.3 selected from the SDSS DR6 at separations of 6-8 arcsec (43-65 kpc) and observed by Chandra for ≈65 ks each. Both members of each pair are detected with good photon statistics to allow us to constrain the column density, spectral slope and intrinsic X-ray luminosity. We also include a recently discovered dual quasar at z = 5 (separation of 21 arcsec, 136 kpc) for which XMM-Newton archival data allow us to detect the two components separately. Using optical spectra we derived bolometric luminosities, BH masses and Eddington ratios that were compared to those of luminous SDSS quasars in the same redshift ranges. We find that the brighter component of both quasar pairs at z ≈ 3.0-3.3 has high luminosities compared to the distribution of SDSS quasars at similar redshift, with J1622A having an order magnitude higher luminosity than the median. This source lies at the luminous end of the z ≈ 3.3 quasar luminosity function. While we cannot conclusively state that the unusually high luminosities of our sources are related to their having a close companion, for J1622A there is only a 3 per cent probability that it is by chance.

  6. Probing black hole accretion in quasar pairs at high redshift

    Science.gov (United States)

    Vignali, C.; Piconcelli, E.; Perna, M.; Hennawi, J.; Gilli, R.; Comastri, A.; Zamorani, G.; Dotti, M.; Mathur, S.

    2018-03-01

    Models and observations suggest that luminous quasar activity is triggered by mergers, so it should preferentially occur in the most massive primordial dark matter haloes, where the frequency of mergers is expected to be the highest. Since the importance of galaxy mergers increases with redshift, we identify the high-redshift Universe as the ideal laboratory for studying dual AGN. Here we present the X-ray properties of two systems of dual quasars at z=3.0-3.3 selected from the SDSS DR6 at separations of 6-8 arcsec (43-65 kpc) and observed by Chandra for ≈65 ks each. Both members of each pair are detected with good photon statistics to allow us to constrain the column density, spectral slope and intrinsic X-ray luminosity. We also include a recently discovered dual quasar at z=5 (separation of 21″, 136 kpc) for which XMM-Newton archival data allow us to detect the two components separately. Using optical spectra we derived bolometric luminosities, BH masses and Eddington ratios that were compared to those of luminous SDSS quasars in the same redshift ranges. We find that the brighter component of both quasar pairs at z ≈ 3.0-3.3 has high luminosities compared to the distribution of SDSS quasars at similar redshift, with J1622A having an order magnitude higher luminosity than the median. This source lies at the luminous end of the z ≈ 3.3 quasar luminosity function. While we cannot conclusively state that the unusually high luminosities of our sources are related to their having a close companion, for J1622A there is only a 3% probability that it is by chance.

  7. σ-holes and π-holes: Similarities and differences.

    Science.gov (United States)

    Politzer, Peter; Murray, Jane S

    2018-04-05

    σ-Holes and π-holes are regions of molecules with electronic densities lower than their surroundings. There are often positive electrostatic potentials associated with them. Through these potentials, the molecule can interact attractively with negative sites, such as lone pairs, π electrons, and anions. Such noncovalent interactions, "σ-hole bonding" and "π-hole bonding," are increasingly recognized as being important in a number of different areas. In this article, we discuss and compare the natures and characteristics of σ-holes and π-holes, and factors that influence the strengths and locations of the resulting electrostatic potentials. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Massive Binary Black Holes in the Cosmic Landscape

    Science.gov (United States)

    Colpi, Monica; Dotti, Massimo

    2011-02-01

    Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly, and can in principle be detected as powerful dual quasars. But, if the black holes reach coalescence, during their inspiral inside the galaxy remnant, then they become the loudest sources of gravitational waves ever in the universe. The Laser Interferometer Space Antenna is being developed to reveal these waves that carry information on the mass and spin of these binary black holes out to very large look-back times. Nature seems to provide a pathway for the formation of these exotic binaries, and a number of key questions need to be addressed: How do massive black holes pair in a merger? Depending on the properties of the underlying galaxies, do black holes always form a close Keplerian binary? If a binary forms, does hardening proceed down to the domain controlled by gravitational wave back reaction? What is the role played by gas and/or stars in braking the black holes, and on which timescale does coalescence occur? Can the black holes accrete on flight and shine during their pathway to coalescence? After outlining key observational facts on dual/binary black holes, we review the progress made in tracing their dynamics in the habitat of a gas-rich merger down to the smallest scales ever probed with the help of powerful numerical simulations. N-Body/hydrodynamical codes have proven to be vital tools for studying their evolution, and progress in this field is expected to grow rapidly in the effort to describe, in full realism, the physics of stars and gas around the black holes, starting from the cosmological large scale of a merger. If detected in the new window provided by the upcoming gravitational wave experiments, binary black holes will provide a deep view

  9. More on Probing Branes with Branes

    OpenAIRE

    Brandhuber, A.; Itzhaki, N.; Sonnenschein, J.; Yankielowicz, S.

    1997-01-01

    We generalize the Gibbons-Wiltshire solution of four dimensional Kaluza-Klein black holes in order to describe Type IIA solutions of bound states of D6 and D0-branes. We probe the solutions with a D6-brane and a D0-brane. We also probe a system of D2+D0-branes and of a D2-brane bound to a F1-string with a D2-brane. A precise agreement between the SYM and the SUGRA calculations is found for the static force as well as for the $v^2$ force in all cases.

  10. Black holes in Lorentz-violating gravity theories

    International Nuclear Information System (INIS)

    Barausse, Enrico; Sotiriou, Thomas P

    2013-01-01

    Lorentz symmetry and the notion of light cones play a central role in the definition of horizons and the existence of black holes. Current observations provide strong indications that astrophysical black holes do exist in Nature. Here we explore what happens to the notion of a black hole in gravity theories where local Lorentz symmetry is violated, and discuss the relevant astrophysical implications. Einstein-aether theory and Hořava gravity are used as the theoretical background for addressing this question. We review earlier results about static, spherically symmetric black holes, which demonstrate that in Lorentz-violating theories there can be a new type of horizon and, hence, a new notion of black hole. We also present both known and new results on slowly rotating black holes in these theories, which provide insights on how generic these new horizons are. Finally, we discuss the differences between black holes in Lorentz-violating theories and in General Relativity, and assess to what extent they can be probed with present and future observations. (paper)

  11. Biomechanical study of the final push-pull in archery.

    Science.gov (United States)

    Leroyer, P; Van Hoecke, J; Helal, J N

    1993-02-01

    The purpose of this study was to analyse archery performance among eight archers of different abilities by means of displacement pull-hand measurements during the final push-pull phase of the shoot. The archers showed an irregular displacement negatively related to their technical level. Displacement signal analysis showed high power levels in both the 0-5 Hz and 8-12 Hz ranges. The latter peak corresponds to electromyographic tremor observed during a prolonged push-pull effort. The results are discussed in relation to some potentially helpful training procedures such as biofeedback and strength conditioning.

  12. A demonstration of NIOSH push-pull ventilation criteria.

    Science.gov (United States)

    Klein, M K

    1987-03-01

    This paper summarizes the results of a study performed on an actual chrome plating tank in order to validate criteria for push-pull ventilation systems developed by Huebener and Hughes at NIOSH. Validation of the criteria was made by taking area industrial hygiene samples for hexavalent and total chrome at ten locations around the plating tank. The sampling was performed during actual production runs or while the tank was operating with a dummy load. The sampling data are summarized. The data show that the push-pull system, operating at Huebener's criteria, could control emissions to below the current standards and guidelines. Conclusions and recommendations are included.

  13. Attentional Push: Augmenting Salience with Shared Attention Modeling

    OpenAIRE

    Gorji, Siavash; Clark, James J.

    2016-01-01

    We present a novel visual attention tracking technique based on Shared Attention modeling. Our proposed method models the viewer as a participant in the activity occurring in the scene. We go beyond image salience and instead of only computing the power of an image region to pull attention to it, we also consider the strength with which other regions of the image push attention to the region in question. We use the term Attentional Push to refer to the power of image regions to direct and man...

  14. Restoration of Hyperspectral Push-Broom Scanner Data

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Nielsen, Allan Aasbjerg; Conradsen, Knut

    1997-01-01

    Several effects combine to distort the multispectral data that are obtained from push-broom scanners. We develop an algorithm for restoration of such data, illustrated on images from the ROSIS scanner. In push-broom scanners variation between elements in the detector array results in a strong...... back into the original spectral space results in noise corrected variables. The noise components will now have been removed from the entire original data set by working on a smaller set of noise contaminated transformed variables only. The application of the above techniques results in a dramatic...

  15. Push-pull optical pumping of pure superposition states

    International Nuclear Information System (INIS)

    Jau, Y.-Y.; Miron, E.; Post, A.B.; Kuzma, N.N.; Happer, W.

    2004-01-01

    A new optical pumping method, 'push-pull pumping', can produce very nearly pure, coherent superposition states between the initial and the final sublevels of the important field-independent 0-0 clock resonance of alkali-metal atoms. The key requirement for push-pull pumping is the use of D1 resonant light which alternates between left and right circular polarization at the Bohr frequency of the state. The new pumping method works for a wide range of conditions, including atomic beams with almost no collisions, and atoms in buffer gases with pressures of many atmospheres

  16. 14 mrad Extraction Line Optics for Push-Pull

    International Nuclear Information System (INIS)

    Nosochkov, Y.; Moffeit, K.; Seryi, A.; Morse, W.; Parker, B.

    2007-01-01

    The ILC design is based on a single Interaction Region (IR) with 14 mrad crossing angle and two detectors in the 'push-pull' configuration, where the detectors can alternately occupy the Interaction Point (IP). Consequently, the IR optics must be compatible with different size detectors designed for different distance L* between the IP and the nearest quadrupole. This paper presents the push-pull optics for the ILC extraction line compatible with L*= 3.5 m to 4.5 m, and the simulation results of extraction beam loss at 500 GeV CM with detector solenoid

  17. Merging Black Holes

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics

  18. Black-hole astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Bender, P. [Univ. of Colorado, Boulder, CO (United States); Bloom, E. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Cominsky, L. [Sonoma State Univ., Rohnert Park, CA (United States). Dept. of Physics and Astronomy] [and others

    1995-07-01

    Black-hole astrophysics is not just the investigation of yet another, even if extremely remarkable type of celestial body, but a test of the correctness of the understanding of the very properties of space and time in very strong gravitational fields. Physicists` excitement at this new prospect for testing theories of fundamental processes is matched by that of astronomers at the possibility to discover and study a new and dramatically different kind of astronomical object. Here the authors review the currently known ways that black holes can be identified by their effects on their neighborhood--since, of course, the hole itself does not yield any direct evidence of its existence or information about its properties. The two most important empirical considerations are determination of masses, or lower limits thereof, of unseen companions in binary star systems, and measurement of luminosity fluctuations on very short time scales.

  19. Black hole gravitohydromagnetics

    CERN Document Server

    Punsly, Brian

    2008-01-01

    Black hole gravitohydromagnetics (GHM) is developed from the rudiments to the frontiers of research in this book. GHM describes plasma interactions that combine the effects of gravity and a strong magnetic field, in the vicinity (ergosphere) of a rapidly rotating black hole. This topic was created in response to the astrophysical quest to understand the central engines of radio loud extragalactic radio sources. The theory describes a "torsional tug of war" between rotating ergospheric plasma and the distant asymptotic plasma that extracts the rotational inertia of the black hole. The recoil from the struggle between electromagnetic and gravitational forces near the event horizon is manifested as a powerful pair of magnetized particle beams (jets) that are ejected at nearly the speed of light. These bipolar jets feed large-scale magnetized plasmoids on scales as large as millions of light years (the radio lobes of extragalactic radio sources). This interaction can initiate jets that transport energy fluxes exc...

  20. Turbulent black holes.

    Science.gov (United States)

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

  1. Anyon black holes

    Science.gov (United States)

    Aghaei Abchouyeh, Maryam; Mirza, Behrouz; Karimi Takrami, Moein; Younesizadeh, Younes

    2018-05-01

    We propose a correspondence between an Anyon Van der Waals fluid and a (2 + 1) dimensional AdS black hole. Anyons are particles with intermediate statistics that interpolates between a Fermi-Dirac statistics and a Bose-Einstein one. A parameter α (0 quasi Fermi-Dirac statistics for α >αc, but a quasi Bose-Einstein statistics for α quasi Bose-Einstein statistics. For α >αc and a range of values of the cosmological constant, there is, however, no event horizon so there is no black hole solution. Thus, for these values of cosmological constants, the AdS Anyon Van der Waals black holes have only quasi Bose-Einstein statistics.

  2. Black holes go supersonic

    Energy Technology Data Exchange (ETDEWEB)

    Leonhardt, Ulf [School of Physics and Astronomy, University of St. Andrews (United Kingdom)

    2001-02-01

    In modern physics, the unification of gravity and quantum mechanics remains a mystery. Gravity rules the macroscopic world of planets, stars and galaxies, while quantum mechanics governs the micro-cosmos of atoms, light quanta and elementary particles. However, cosmologists believe that these two disparate worlds may meet at the edges of black holes. Now Luis Garay, James Anglin, Ignacio Cirac and Peter Zoller at the University of Innsbruck in Austria have proposed a realistic way to make an artificial 'sonic' black hole in a tabletop experiment (L J Garay et al. 2000 Phys. Rev. Lett. 85 4643). In the February issue of Physics World, Ulf Leonhardt of the School of Physics and Astronomy, University of St. Andrews, UK, explains how the simulated black holes work. (U.K.)

  3. Black Hole Paradoxes

    International Nuclear Information System (INIS)

    Joshi, Pankaj S.; Narayan, Ramesh

    2016-01-01

    We propose here that the well-known black hole paradoxes such as the information loss and teleological nature of the event horizon are restricted to a particular idealized case, which is the homogeneous dust collapse model. In this case, the event horizon, which defines the boundary of the black hole, forms initially, and the singularity in the interior of the black hole at a later time. We show that, in contrast, gravitational collapse from physically more realistic initial conditions typically leads to the scenario in which the event horizon and space-time singularity form simultaneously. We point out that this apparently simple modification can mitigate the causality and teleological paradoxes, and also lends support to two recently suggested solutions to the information paradox, namely, the ‘firewall’ and ‘classical chaos’ proposals. (paper)

  4. Bringing Black Holes Home

    Science.gov (United States)

    Furmann, John M.

    2003-03-01

    Black holes are difficult to study because they emit no light. To overcome this obstacle, scientists are trying to recreate a black hole in the laboratory. The article gives an overview of the theories of Einstein and Hawking as they pertain to the construction of the Large Hadron Collider (LHC) near Geneva, Switzerland, scheduled for completion in 2006. The LHC will create two beams of protons traveling in opposing directions that will collide and create a plethora of scattered elementary particles. Protons traveling in opposite directions at very high velocities may create particles that come close enough to each other to feel their compacted higher dimensions and create a mega force of gravity that can create tiny laboratory-sized black holes for fractions of a second. The experiments carried out with LHC will be used to test modern string theory and relativity.

  5. Laboratory Observation of Electron Phase-Space Holes during Magnetic Reconnection

    International Nuclear Information System (INIS)

    Fox, W.; Porkolab, M.; Egedal, J.; Katz, N.; Le, A.

    2008-01-01

    We report the observation of large-amplitude, nonlinear electrostatic structures, identified as electron phase-space holes, during magnetic reconnection experiments on the Versatile Toroidal Facility at MIT. The holes are positive electric potential spikes, observed on high-bandwidth (∼2 GHz) Langmuir probes. Investigations with multiple probes establish that the holes travel at or above the electron thermal speed and have a three-dimensional, approximately spherical shape, with a scale size ∼2 mm. This corresponds to a few electron gyroradii, or many tens of Debye lengths, which is large compared to holes considered in simulations and observed by satellites, whose length scale is typically only a few Debye lengths. Finally, a statistical study over many discharges confirms that the holes appear in conjunction with the large inductive electric fields and the creation of energetic electrons associated with the magnetic energy release

  6. The Galaxy Evolution Probe

    Science.gov (United States)

    Glenn, Jason; Galaxy Evolution Probe Team

    2018-01-01

    The Galaxy Evolution Probe (GEP) is a concept for a far-infrared observatory to survey large regions of sky for star-forming galaxies from z = 0 to beyond z = 3. Our knowledge of galaxy formation is incomplete and requires uniform surveys over a large range of redshifts and environments to accurately describe mass assembly, star formation, supermassive black hole growth, interactions between these processes, and what led to their decline from z ~ 2 to the present day. Infrared observations are sensitive to dusty, star-forming galaxies, which have bright polycyclic aromatic hydrocarbon (PAH) emission features and warm dust continuum in the rest-frame mid infrared and cooler thermal dust emission in the far infrared. Unlike previous far-infrared continuum surveys, the GEP will measure photometric redshifts commensurate with galaxy detections from PAH emission and Si absorption features, without the need for obtaining spectroscopic redshifts of faint counterparts at other wavelengths.The GEP design includes a 2 m diameter telescope actively cooled to 4 K and two instruments: (1) An imager covering 10 to 300 um with 25 spectral resolution R ~ 8 bands (with lower R at the longest wavelengths) to detect star-forming galaxies and measure their redshifts photometrically. (2) A 23 – 190 um, R ~ 250 dispersive spectrometer for redshift confirmation and identification of obscured AGN using atomic fine-structure lines. Lines including [Ne V], [O IV], [O III], [O I], and [C II] will probe gas physical conditions, radiation field hardness, and metallicity. Notionally, the GEP will have a two-year mission: galaxy surveys with photometric redshifts in the first year and a second year devoted to follow-up spectroscopy. A comprehensive picture of star formation in galaxies over the last 10 billion years will be assembled from cosmologically relevant volumes, spanning environments from field galaxies and groups, to protoclusters, to dense galaxy clusters.Commissioned by NASA, the

  7. Slowly balding black holes

    International Nuclear Information System (INIS)

    Lyutikov, Maxim; McKinney, Jonathan C.

    2011-01-01

    The 'no-hair' theorem, a key result in general relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the no-hair theorem is not formally applicable for black holes formed from the collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively ''frozen in'' the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes N B =eΦ ∞ /(πc(ℎ/2π)), where Φ ∞ ≅2π 2 B NS R NS 3 /(P NS c) is the initial magnetic flux through the hemispheres of the progenitor and out to infinity. We test this theoretical result via 3-dimensional general relativistic plasma simulations of rotating black holes that start with a neutron star dipole magnetic field with no currents initially present outside the event horizon. The black hole's magnetosphere subsequently relaxes to the split-monopole magnetic field geometry with self-generated currents outside the event horizon. The dissipation of the resulting equatorial current sheet leads to a slow loss of the anchored flux tubes, a process that balds the black hole on long resistive time scales rather than the short light-crossing time scales expected from the vacuum no-hair theorem.

  8. Modeling black hole evaporation

    CERN Document Server

    Fabbri, Alessandro

    2005-01-01

    The scope of this book is two-fold: the first part gives a fully detailed and pedagogical presentation of the Hawking effect and its physical implications, and the second discusses the backreaction problem, especially in connection with exactly solvable semiclassical models that describe analytically the black hole evaporation process. The book aims to establish a link between the general relativistic viewpoint on black hole evaporation and the new CFT-type approaches to the subject. The detailed discussion on backreaction effects is also extremely valuable.

  9. Characterizing Black Hole Mergers

    Science.gov (United States)

    Baker, John; Boggs, William Darian; Kelly, Bernard

    2010-01-01

    Binary black hole mergers are a promising source of gravitational waves for interferometric gravitational wave detectors. Recent advances in numerical relativity have revealed the predictions of General Relativity for the strong burst of radiation generated in the final moments of binary coalescence. We explore features in the merger radiation which characterize the final moments of merger and ringdown. Interpreting the waveforms in terms of an rotating implicit radiation source allows a unified phenomenological description of the system from inspiral through ringdown. Common features in the waveforms allow quantitative description of the merger signal which may provide insights for observations large-mass black hole binaries.

  10. Moulting Black Holes

    OpenAIRE

    Bena, Iosif; Chowdhury, Borun D.; de Boer, Jan; El-Showk, Sheer; Shigemori, Masaki

    2011-01-01

    We find a family of novel supersymmetric phases of the D1-D5 CFT, which in certain ranges of charges have more entropy than all known ensembles. We also find bulk BPS configurations that exist in the same range of parameters as these phases, and have more entropy than a BMPV black hole; they can be thought of as coming from a BMPV black hole shedding a "hair" condensate outside of the horizon. The entropy of the bulk configurations is smaller than that of the CFT phases, which indicates that ...

  11. Are black holes springlike?

    Science.gov (United States)

    Good, Michael R. R.; Ong, Yen Chin

    2015-02-01

    A (3 +1 )-dimensional asymptotically flat Kerr black hole angular speed Ω+ can be used to define an effective spring constant, k =m Ω+2. Its maximum value is the Schwarzschild surface gravity, k =κ , which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: 2 π T =κ -k . Hooke's law, in the extremal limit, provides the force F =1 /4 , which is consistent with the conjecture of maximum force in general relativity.

  12. Dancing with Black Holes

    Science.gov (United States)

    Aarseth, S. J.

    2008-05-01

    We describe efforts over the last six years to implement regularization methods suitable for studying one or more interacting black holes by direct N-body simulations. Three different methods have been adapted to large-N systems: (i) Time-Transformed Leapfrog, (ii) Wheel-Spoke, and (iii) Algorithmic Regularization. These methods have been tried out with some success on GRAPE-type computers. Special emphasis has also been devoted to including post-Newtonian terms, with application to moderately massive black holes in stellar clusters. Some examples of simulations leading to coalescence by gravitational radiation will be presented to illustrate the practical usefulness of such methods.

  13. Scattering from black holes

    International Nuclear Information System (INIS)

    Futterman, J.A.H.; Handler, F.A.; Matzner, R.A.

    1987-01-01

    This book provides a comprehensive treatment of the propagation of waves in the presence of black holes. While emphasizing intuitive physical thinking in their treatment of the techniques of analysis of scattering, the authors also include chapters on the rigorous mathematical development of the subject. Introducing the concepts of scattering by considering the simplest, scalar wave case of scattering by a spherical (Schwarzschild) black hole, the book then develops the formalism of spin weighted spheroidal harmonics and of plane wave representations for neutrino, electromagnetic, and gravitational scattering. Details and results of numerical computations are given. The techniques involved have important applications (references are given) in acoustical and radar imaging

  14. Virtual Black Holes

    OpenAIRE

    Hawking, Stephen W.

    1995-01-01

    One would expect spacetime to have a foam-like structure on the Planck scale with a very high topology. If spacetime is simply connected (which is assumed in this paper), the non-trivial homology occurs in dimension two, and spacetime can be regarded as being essentially the topological sum of $S^2\\times S^2$ and $K3$ bubbles. Comparison with the instantons for pair creation of black holes shows that the $S^2\\times S^2$ bubbles can be interpreted as closed loops of virtual black holes. It is ...

  15. Superfluid Black Holes.

    Science.gov (United States)

    Hennigar, Robie A; Mann, Robert B; Tjoa, Erickson

    2017-01-13

    We present what we believe is the first example of a "λ-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid ^{4}He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically anti-de Sitter hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.

  16. Magnonic Black Holes.

    Science.gov (United States)

    Roldán-Molina, A; Nunez, Alvaro S; Duine, R A

    2017-02-10

    We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons-the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

  17. Partons and black holes

    International Nuclear Information System (INIS)

    Susskind, L.; Griffin, P.

    1994-01-01

    A light-front renormalization group analysis is applied to study matter which falls into massive black holes, and the related problem of matter with transplankian energies. One finds that the rate of matter spreading over the black hole's horizon unexpectedly saturates the causality bound. This is related to the transverse growth behavior of transplankian particles as their longitudinal momentum increases. This growth behavior suggests a natural mechanism to implement 't Hooft's scenario that the universe is an image of data stored on a 2 + 1 dimensional hologram-like projection

  18. Over spinning a black hole?

    Energy Technology Data Exchange (ETDEWEB)

    Bouhmadi-Lopez, Mariam; Cardoso, Vitor; Nerozzi, Andrea; Rocha, Jorge V, E-mail: mariam.bouhmadi@ist.utl.pt, E-mail: vitor.cardoso@ist.utl.pt, E-mail: andrea.nerozzi@ist.utl.pt, E-mail: jorge.v.rocha@ist.utl.pt [CENTRA, Department de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049 Lisboa (Portugal)

    2011-09-22

    A possible process to destroy a black hole consists on throwing point particles with sufficiently large angular momentum into the black hole. In the case of Kerr black holes, it was shown by Wald that particles with dangerously large angular momentum are simply not captured by the hole, and thus the event horizon is not destroyed. Here we reconsider this gedanken experiment for black holes in higher dimensions. We show that this particular way of destroying a black hole does not succeed and that Cosmic Censorship is preserved.

  19. Does delayed pushing in the second stage of labor impact perinatal outcomes?

    Science.gov (United States)

    Frey, Heather A; Tuuli, Methodius G; Cortez, Sarah; Odibo, Anthony O; Roehl, Kimberly A; Shanks, Anthony L; Macones, George A; Cahill, Alison G

    2012-11-01

    To estimate maternal, neonatal, and labor outcomes associated with delayed pushing. A retrospective cohort study of all consecutive women admitted to a single institution in labor at term who reached the second stage of labor. Pregnancies with multiple fetuses or major anomalies were excluded. Delayed pushing was defined as initiation of pushing ≥60 minutes after complete dilatation. Primary outcome was mode of delivery. Multivariable logistic regression was used to control for confounding. Of the 5290 women who met inclusion criteria, 471 (8.9%) employed delayed pushing, and 4819 (91.1%) pushed immediately. Delayed pushing was associated with increased rates of cesarean, operative vaginal delivery, maternal fever, and lower arterial cord pH. Duration of the second stage and length of time spent pushing were significantly longer with delayed pushing. Delayed pushing is associated with lower rates of spontaneous vaginal delivery and increased adverse maternal and neonatal outcomes. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  20. Black Hole Scrambling from Hydrodynamics.

    Science.gov (United States)

    Grozdanov, Sašo; Schalm, Koenraad; Scopelliti, Vincenzo

    2018-06-08

    We argue that the gravitational shock wave computation used to extract the scrambling rate in strongly coupled quantum theories with a holographic dual is directly related to probing the system's hydrodynamic sound modes. The information recovered from the shock wave can be reconstructed in terms of purely diffusionlike, linearized gravitational waves at the horizon of a single-sided black hole with specific regularity-enforced imaginary values of frequency and momentum. In two-derivative bulk theories, this horizon "diffusion" can be related to late-time momentum diffusion via a simple relation, which ceases to hold in higher-derivative theories. We then show that the same values of imaginary frequency and momentum follow from a dispersion relation of a hydrodynamic sound mode. The frequency, momentum, and group velocity give the holographic Lyapunov exponent and the butterfly velocity. Moreover, at this special point along the sound dispersion relation curve, the residue of the retarded longitudinal stress-energy tensor two-point function vanishes. This establishes a direct link between a hydrodynamic sound mode at an analytically continued, imaginary momentum and the holographic butterfly effect. Furthermore, our results imply that infinitely strongly coupled, large-N_{c} holographic theories exhibit properties similar to classical dilute gases; there, late-time equilibration and early-time scrambling are also controlled by the same dynamics.

  1. Black Hole Hunters Set New Distance Record

    Science.gov (United States)

    2010-01-01

    around each other in a diabolic waltz, with a period of about 32 hours. The astronomers also found that the black hole is stripping matter away from the star as they orbit each other. "This is indeed a very 'intimate' couple," notes collaborator Robin Barnard. "How such a tightly bound system has been formed is still a mystery." Only one other system of this type has previously been seen, but other systems comprising a black hole and a companion star are not unknown to astronomers. Based on these systems, the astronomers see a connection between black hole mass and galactic chemistry. "We have noticed that the most massive black holes tend to be found in smaller galaxies that contain less 'heavy' chemical elements," says Crowther [2]. "Bigger galaxies that are richer in heavy elements, such as the Milky Way, only succeed in producing black holes with smaller masses." Astronomers believe that a higher concentration of heavy chemical elements influences how a massive star evolves, increasing how much matter it sheds, resulting in a smaller black hole when the remnant finally collapses. In less than a million years, it will be the Wolf-Rayet star's turn to go supernova and become a black hole. "If the system survives this second explosion, the two black holes will merge, emitting copious amounts of energy in the form of gravitational waves as they combine [3]," concludes Crowther. However, it will take some few billion years until the actual merger, far longer than human timescales. "Our study does however show that such systems might exist, and those that have already evolved into a binary black hole might be detected by probes of gravitational waves, such as LIGO or Virgo [4]." Notes [1] Stellar-mass black holes are the extremely dense, final remnants of the collapse of very massive stars. These black holes have masses up to around twenty times the mass of the Sun, as opposed to supermassive black holes, found in the centre of most galaxies, which can weigh a million to a

  2. Modelling a technology push by using hybrid franchising

    NARCIS (Netherlands)

    Fredriks, Jan; Pennink, Bartjan; Simaputang, T.; Siswanto, J.

    2014-01-01

    Introducing a technology push to stimulate entrepreneurship in remote areas in developing countries can be examined in the context of a franchising model (social or commercial franchising). The results of this study (fieldwork in Kalimantan, Indonesia) point to a high feasibility of introducing a

  3. Nuclear fuel cycle: research and development and push technologies

    International Nuclear Information System (INIS)

    Oliveira, Wagner dos Santos

    2002-01-01

    The scope of this work is to show the importance of 'push technologies in the development of the Nuclear Fuel Cycle more specifically the so called 'Projeto Conversao' PROCON. This R and D activities lead to the design of special equipment, new metallic and polymer materials. (author)

  4. Push an pull forces in the building and construction industry

    NARCIS (Netherlands)

    Frings-Dresen, M. H. W.; Windhorst, Judith; Hoozemans, M. J M; Van Der Beek, Allard J.; Van der Molen, Henk F.

    2000-01-01

    Push and pull activities are increasing in the building and construction industry. These activities can be assumed as one of the risk factors for the development of low back and upper extremity complaints. For a risk evaluation, besides the frequency and the duration of the activities, information

  5. Development of remote fuel pushing system in Reprocessing Plant, Tarapur

    International Nuclear Information System (INIS)

    Chandra, Munish; Coelho, G.; Kodilkar, S.S.; Mishra, A.K.; Bajpai, D.D.; Nair, M.K.T.

    1990-01-01

    Power Reactor Fuel Reprocessing Plant (PREFRE), Tarapur has been processing spent fuel arising from Pressurized Heavy Water Reactors for quite some time. The process adopted in the plant is purex process with chopleach head end treatment. The head end treatment involves loading of ten spent fuel bundles in the charging cask at a time in the fuel bay and aligning the cask with the transfer port and subsequently pushing all the ten bundles together into the fuel magazine. At present the fuel is pushed into the magazine manually. Since the ten bundles weigh approximately 200 Kg. and involves pushing of 9.4 meters length, the operation is carried out using stainless steel screwed pipes, in steps of five lengths. The entire operation requires a large number of trained skilled workers and is found to be tedious. To solve this problem a hydraulic cum pneumatic fuel pushing system has been designed, fabricated, tested and is in the process of installation in the fuel handling area. This paper describes various requirements, constraints and dimensional details arising in the incorporation of such a system to be back fitted in an existing plant, though many of these constraints can be avoided in future plants. Further, complete sequence of operations, technical specifications regarding the telescopic hydraulic power pack and associated controls incorporated in the system are highlighted. (author). 2 figs

  6. Optical Pushing: A Tool for Parallelized Biomolecule Manipulation

    NARCIS (Netherlands)

    Sitters, G.; Laurens, N.; de Rijk, E.J.; Kress, H.; Peterman, E.J.G.; Wuite, G.J.L.

    2016-01-01

    The ability to measure and manipulate single molecules has greatly advanced the field of biophysics. Yet, the addition of more single-molecule tools that enable one to measure in a parallel fashion is important to diversify the questions that can be addressed. Here we present optical pushing (OP), a

  7. 'Pushing the boundaries of interpretation': The link between the ...

    African Journals Online (AJOL)

    'Pushing the boundaries of interpretation': The link between the nature and purpose of missionary records and the underutilisation of the Roman Catholic missionary ... The article uses the author's experience with Roman Catholic missionary archives in South-western as a window through which to project into the general ...

  8. Pushing Firm Boundaries through Research and Open Innovation

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2011-01-01

    provide into the company and bring forward the effect it has inside a company when performing open innovation together with research partners. We seek to bring forward how performing university-research collaboration can also change the practices inside a company and thus push the firm boundaries in new...

  9. NASA Green Propulsion Technologies Pushing Aviation to New Heights

    Science.gov (United States)

    Free, James M.; Jennings, Francis T.; Adanich, Emery; Del Rosario, Ruben; Felder, James L.

    2014-01-01

    Center Director Free is providing the Keynote at the Disruptive Propulsion Conference, sponsored by Cranfield University, Cranfield, Bedfordshire, England in November. Director Free will be presenting a PowerPoint presentation titled, NASA Green Propulsion Technologies Pushing Aviation to New Heights at both the conference and a meeting at the Royal Aeronautical Society.

  10. Nonsingular black hole

    Energy Technology Data Exchange (ETDEWEB)

    Chamseddine, Ali H. [American University of Beirut, Physics Department, Beirut (Lebanon); I.H.E.S., Bures-sur-Yvette (France); Mukhanov, Viatcheslav [Niels Bohr Institute, Niels Bohr International Academy, Copenhagen (Denmark); Ludwig-Maximilians University, Theoretical Physics, Munich (Germany); MPI for Physics, Munich (Germany)

    2017-03-15

    We consider the Schwarzschild black hole and show how, in a theory with limiting curvature, the physical singularity ''inside it'' is removed. The resulting spacetime is geodesically complete. The internal structure of this nonsingular black hole is analogous to Russian nesting dolls. Namely, after falling into the black hole of radius r{sub g}, an observer, instead of being destroyed at the singularity, gets for a short time into the region with limiting curvature. After that he re-emerges in the near horizon region of a spacetime described by the Schwarzschild metric of a gravitational radius proportional to r{sub g}{sup 1/3}. In the next cycle, after passing the limiting curvature, the observer finds himself within a black hole of even smaller radius proportional to r{sub g}{sup 1/9}, and so on. Finally after a few cycles he will end up in the spacetime where he remains forever at limiting curvature. (orig.)

  11. When Black Holes Collide

    Science.gov (United States)

    Baker, John

    2010-01-01

    Among the fascinating phenomena predicted by General Relativity, Einstein's theory of gravity, black holes and gravitational waves, are particularly important in astronomy. Though once viewed as a mathematical oddity, black holes are now recognized as the central engines of many of astronomy's most energetic cataclysms. Gravitational waves, though weakly interacting with ordinary matter, may be observed with new gravitational wave telescopes, opening a new window to the universe. These observations promise a direct view of the strong gravitational dynamics involving dense, often dark objects, such as black holes. The most powerful of these events may be merger of two colliding black holes. Though dark, these mergers may briefly release more energy that all the stars in the visible universe, in gravitational waves. General relativity makes precise predictions for the gravitational-wave signatures of these events, predictions which we can now calculate with the aid of supercomputer simulations. These results provide a foundation for interpreting expect observations in the emerging field of gravitational wave astronomy.

  12. Proximal Probes Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

  13. Probe Techniques. Introductory Remarks

    Energy Technology Data Exchange (ETDEWEB)

    Emeleus, K. G. [School of Physics and Applied Mathematics, Queen' s University, Belfast (United Kingdom)

    1968-04-15

    In this brief introduction to the session on probes, the history of theii development is first touched on briefly. Reference is then made to the significance of the work to be described by Medicus, for conductivity and recombination calculations, and by Lam and Su, for a wide range of medium and higher pressure plasmas. Finally, a number of other probe topics are mentioned, including multiple probes; probes in electronegative plasmas; resonance probes; probes in noisy discharges; probes as oscillation detectors; use of probes where space-charge is not negligible. (author)

  14. Black holes and quantum mechanics

    CERN Document Server

    Wilczek, Frank

    1995-01-01

    1. Qualitative introduction to black holes : classical, quantum2. Model black holes and model collapse process: The Schwarzschild and Reissner-Nordstrom metrics, The Oppenheimer-Volkov collapse scenario3. Mode mixing4. From mode mixing to radiance.

  15. Quantum Mechanics of Black Holes

    OpenAIRE

    Giddings, Steven B.

    1994-01-01

    These lectures give a pedagogical review of dilaton gravity, Hawking radiation, the black hole information problem, and black hole pair creation. (Lectures presented at the 1994 Trieste Summer School in High Energy Physics and Cosmology)

  16. Quantum aspects of black holes

    CERN Document Server

    2015-01-01

    Beginning with an overview of the theory of black holes by the editor, this book presents a collection of ten chapters by leading physicists dealing with the variety of quantum mechanical and quantum gravitational effects pertinent to black holes. The contributions address topics such as Hawking radiation, the thermodynamics of black holes, the information paradox and firewalls, Monsters, primordial black holes, self-gravitating Bose-Einstein condensates, the formation of small black holes in high energetic collisions of particles, minimal length effects in black holes and small black holes at the Large Hadron Collider. Viewed as a whole the collection provides stimulating reading for researchers and graduate students seeking a summary of the quantum features of black holes.

  17. Aspects of hairy black holes

    Energy Technology Data Exchange (ETDEWEB)

    Anabalón, Andrés, E-mail: andres.anabalon-at@uai.cl [Departamento de Ciencias, Facultad de Artes Liberales y Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Viña del Mar (Chile); Astefanesei, Dumitru [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso (Chile)

    2015-03-26

    We review the existence of exact hairy black holes in asymptotically flat, anti-de Sitter and de Sitter space-times. We briefly discuss the issue of stability and the charging of the black holes with a Maxwell field.

  18. Predicting Bobsled Pushing Ability from Various Combine Testing Events.

    Science.gov (United States)

    Tomasevicz, Curtis L; Ransone, Jack W; Bach, Christopher W

    2018-03-12

    The requisite combination of speed, power, and strength necessary for a bobsled push athlete coupled with the difficulty in directly measuring pushing ability makes selecting effective push crews challenging. Current practices by USA Bobsled and Skeleton (USABS) utilize field combine testing to assess and identify specifically selected performance variables in an attempt to best predict push performance abilities. Combine data consisting of 11 physical performance variables were collected from 75 subjects across two winter Olympic qualification years (2009 and 2013). These variables were sprints of 15-, 30-, and 60 m, a flying 30 m sprint, a standing broad jump, a shot toss, squat, power clean, body mass, and dry-land brake and side bobsled pushes. Discriminant Analysis (DA) in addition to Principle Component Analysis (PCA) was used to investigate two cases (Case 1: Olympians vs. non-Olympians; Case 2: National Team vs. non-National Team). Using these 11 variables, DA led to a classification rule that proved capable of identifying Olympians from non-Olympians and National Team members from non-National Team members with 9.33% and 14.67% misclassification rates, respectively. The PCA was used to find similar test variables within the combine that provided redundant or useless data. After eliminating the unnecessary variables, DA on the new combinations showed that 8 (Case 1) and 20 (Case 2) other combinations with fewer performance variables yielded misclassification rates as low as 6.67% and 13.33% respectively. Utilizing fewer performance variables can allow governing bodies in many other sports to create more appropriate combine testing that maximize accuracy, while minimizing irrelevant and redundant strategies.

  19. Incorporating pushing in exclusion-process models of cell migration.

    Science.gov (United States)

    Yates, Christian A; Parker, Andrew; Baker, Ruth E

    2015-05-01

    The macroscale movement behavior of a wide range of isolated migrating cells has been well characterized experimentally. Recently, attention has turned to understanding the behavior of cells in crowded environments. In such scenarios it is possible for cells to interact, inducing neighboring cells to move in order to make room for their own movements or progeny. Although the behavior of interacting cells has been modeled extensively through volume-exclusion processes, few models, thus far, have explicitly accounted for the ability of cells to actively displace each other in order to create space for themselves. In this work we consider both on- and off-lattice volume-exclusion position-jump processes in which cells are explicitly allowed to induce movements in their near neighbors in order to create space for themselves to move or proliferate into. We refer to this behavior as pushing. From these simple individual-level representations we derive continuum partial differential equations for the average occupancy of the domain. We find that, for limited amounts of pushing, comparison between the averaged individual-level simulations and the population-level model is nearly as good as in the scenario without pushing. Interestingly, we find that, in the on-lattice case, the diffusion coefficient of the population-level model is increased by pushing, whereas, for the particular off-lattice model that we investigate, the diffusion coefficient is reduced. We conclude, therefore, that it is important to consider carefully the appropriate individual-level model to use when representing complex cell-cell interactions such as pushing.

  20. Exciton and Hole-Transfer Dynamics in Polymer: Fullerene Blends

    Directory of Open Access Journals (Sweden)

    van Loosdrecht P. H. M.

    2013-03-01

    Full Text Available Ultrafast hole transfer dynamics from fullerene derivative to polymer in bulk heterojunction blends are studied with visible-pump - IR-probe spectroscopy. The hole transfer process is found to occur in 50/300 fs next to the interface, while a longer 15-ps time is attributed to exciton diffusion towards interface in PC71BM domains. High polaron generation efficiency in P3HT blends indicates excellent intercalation between the polymer and the fullerene even at highest PC71BM concentration thereby yielding a valuable information on the blend morphology.

  1. Cart pushing: the effect of magnitude and direction of push force, and of trunk inclination on low back loading

    NARCIS (Netherlands)

    Hoozemans, M.J.M.; Faber, G.S.; Slaghuis, W.; van Dieen, J.H.

    2007-01-01

    The primary objective of the present study was to quantify the relative effect of the magnitude and direction of the exerted push force and of trunk inclination on the mechanical load at the low back using a regression analysis for correlated data. In addition, we explored the effects of handle

  2. Neutrino constraints that transform black holes into grey holes

    International Nuclear Information System (INIS)

    Ruderfer, M.

    1982-01-01

    Existing black hole theory is found to be defective in its neglect of the physical properties of matter and radiation at superhigh densities. Nongravitational neutrino effects are shown to be physically relevant to the evolution of astronomical black holes and their equations of state. Gravitational collapse to supernovae combined with the Davis and Ray vacuum solution for neutrinos limit attainment of a singularity and require black holes to evolve into ''grey holes''. These allow a better justification than do black holes for explaining the unique existence of galactic masses. (Auth.)

  3. Warped products and black holes

    International Nuclear Information System (INIS)

    Hong, Soon-Tae

    2005-01-01

    We apply the warped product space-time scheme to the Banados-Teitelboim-Zanelli black holes and the Reissner-Nordstroem-anti-de Sitter black hole to investigate their interior solutions in terms of warped products. It is shown that there exist no discontinuities of the Ricci and Einstein curvatures across event horizons of these black holes

  4. Magnetohydrodynamics near a black hole

    International Nuclear Information System (INIS)

    Wilson, J.R.

    1975-01-01

    A numerical computer study of hydromagnetic flow near a black hole is presented. First, the equations of motion are developed to a form suitable for numerical computations. Second, the results of calculations describing the magnetic torques exerted by a rotating black hole on a surrounding magnetic plasma and the electric charge that is induced on the surface of the black hole are presented. (auth)

  5. X-rays as a probe of the Universe

    Indian Academy of Sciences (India)

    Table of contents. X-rays as a probe of the Universe · Probing the Universe ….. Flux = sT4 umax = 1011 T (in Kelvin) · History of x-ray astronomy · X-ray Production · X-ray spectra · Celestial sphere as seen by UHURU (1970) · Slide 8 · X-rays from accreting binary systems · Slide 10 · Neutron stars: Black Hole: · Primary X-ray ...

  6. Evolving Coronal Holes and Interplanetary Erupting Stream ...

    Indian Academy of Sciences (India)

    prominences, have a significantly higher rate of occurrence in the vicinity of coronal .... coronal holes due to the birth of new holes or the growth of existing holes. .... Statistics of newly formed coronal hole areas (NFOCHA) associated with ...

  7. Thermodynamic stability of modified Schwarzschild-AdS black hole in rainbow gravity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong-Wan [Chonbuk National University, Research Institute of Physics and Chemistry, Jeonju (Korea, Republic of); Kim, Seung Kook [Seonam University, Department of Physical Therapy, Namwon (Korea, Republic of); Park, Young-Jai [Sogang University, Department of Physics, Seoul (Korea, Republic of)

    2016-10-15

    In this paper, we have extended the previous study of the thermodynamics and phase transition of the Schwarzschild black hole in the rainbow gravity to the Schwarzschild-AdS black hole where metric depends on the energy of a probe. Making use of the Heisenberg uncertainty principle and the modified dispersion relation, we have obtained the modified local Hawking temperature and thermodynamic quantities in an isothermal cavity. Moreover, we carry out the analysis of constant temperature slices of a black hole. As a result, we have shown that there also exists another Hawking-Page-like phase transition in which case a locally stable small black hole tunnels into a globally stable large black hole as well as the standard Hawking-Page phase transition from a hot flat space to a black hole. (orig.)

  8. From binary black hole simulation to triple black hole simulation

    International Nuclear Information System (INIS)

    Bai Shan; Cao Zhoujian; Han, Wen-Biao; Lin, Chun-Yu; Yo, Hwei-Jang; Yu, Jui-Ping

    2011-01-01

    Black hole systems are among the most promising sources for a gravitational wave detection project. Now, China is planning to construct a space-based laser interferometric detector as a follow-on mission of LISA in the near future. Aiming to provide some theoretical support to this detection project on the numerical relativity side, we focus on black hole systems simulation in this work. Considering the globular galaxy, multiple black hole systems also likely to exist in our universe and play a role as a source for the gravitational wave detector we are considering. We will give a progress report in this paper on our black hole system simulation. More specifically, we will present triple black hole simulation together with binary black hole simulation. On triple black hole simulations, one novel perturbational method is proposed.

  9. Probes, Moons, and Kinetic Plasma Wakes

    Science.gov (United States)

    Hutchinson, I. H.; Malaspina, D.; Zhou, C.

    2017-10-01

    Nonmagnetic objects as varied as probes in tokamaks or moons in space give rise to flowing plasma wakes in which strong distortions of the ion and electron velocity distributions cause electrostatic instabilities. Non-linear phenomena such as electron holes are then produced. Historic probe theory largely ignores the resulting unstable character of the wake, but since we can now simulate computationally the non-linear wake phenomena, a timely challenge is to reassess the influence of these instabilities both on probe measurements and on the wakes themselves. Because the electron instability wavelengths are very short (typically a few Debye-lengths), controlled laboratory experiments face serious challenges in diagnosing them. That is one reason why they have long been neglected as an influence in probe interpretation. Space-craft plasma observations, by contrast, easily obtain sub-Debye-length resolution, but have difficulty with larger-scale reconstruction of the plasma spatial variation. In addition to surveying our developing understanding of wakes in magnetized plasmas, ongoing analysis of Artemis data concerning electron holes observed in the solar-wind lunar wake will be featured. Work partially supported by NASA Grant NNX16AG82G.

  10. Eternal higher spin black holes: a thermofield Interpretation

    International Nuclear Information System (INIS)

    Castro, Alejandra; Iqbal, Nabil; Llabrés, Eva

    2016-01-01

    We study Lorentzian eternal black holes in the Chern-Simons sector of AdS 3 higher spin gravity. We probe such black holes using bulk Wilson lines and motivate new regularity conditions that must be obeyed by the bulk connections in order for the geometry to be consistent with an interpretation as a thermofield state in the dual CFT 2 . We demonstrate that any higher spin black hole may be placed in a gauge that satisfies these conditions: this is the Chern-Simons analogue of the construction of Kruskal coordinates that permit passage through the black hole horizon. We also argue that the Wilson line provides a higher-spin notion of causality in higher spin gravity that can be used to associate a Penrose diagram with the black hole. We present some applications of the formalism, including a study of the time-dependent entanglement entropy arising from the higher spin black hole interior and evidence for an emergent AdS 2 region in the extremal limit.

  11. Strong gravity effects in accreting black-hole systems

    International Nuclear Information System (INIS)

    Niedzwiecki, A.

    2006-01-01

    I briefly review current status of studying effects of strong gravity in X-ray astronomy. Matter accreting onto a black hole probes the relativistic region of space-time and the high-energy radiation it produces should contain signatures of strong gravity effects. Current X-ray observations provide the evidence that the observed emission originates, in some cases, at a distance of a few gravitational radii from a black hole. Moreover, certain observations invoke interpretations favouring rapid rotation of the black hole. Some observational properties of black hole systems are supposed to result from the lack of a material surface in these objects. I consider further effects, specific for the black hole environment, which can be studied in X-ray data. Bulk motion Comptonization, which would directly reveal converging flow of matter plunging into a black hole, is unlikely to be important in formation of X-ray spectra. Similarly, Penrose processes are unlikely to give observational effects, although this issue has not been thoroughly studied so far for all plausible radiative mechanisms. (author)

  12. Electron and hole transport in ambipolar, thin film pentacene transistors

    International Nuclear Information System (INIS)

    Saudari, Sangameshwar R.; Kagan, Cherie R.

    2015-01-01

    Solution-processed, ambipolar, thin-film pentacene field-effect transistors were employed to study both electron and hole transport simultaneously in a single, organic solid-state device. Electron and hole mobilities were extracted from the respective unipolar saturation regimes and show thermally activated behavior and gate voltage dependence. We fit the gate voltage dependent saturation mobility to a power law to extract the characteristic Meyer-Neldel (MN) energy, a measure of the width of the exponential distribution of localized states extending into the energy gap of the organic semiconductor. The MN energy is ∼78 and ∼28 meV for electrons and holes, respectively, which reflects a greater density of localized tail states for electrons than holes. This is consistent with the lower measured electron than hole mobility. For holes, the well-behaved linear regime allows for four-point probe measurement of the contact resistance independent mobility and separate characterization of the width of the localized density of states, yielding a consistent MN energy of 28 meV

  13. Electron and hole transport in ambipolar, thin film pentacene transistors

    Energy Technology Data Exchange (ETDEWEB)

    Saudari, Sangameshwar R. [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Kagan, Cherie R. [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2015-01-21

    Solution-processed, ambipolar, thin-film pentacene field-effect transistors were employed to study both electron and hole transport simultaneously in a single, organic solid-state device. Electron and hole mobilities were extracted from the respective unipolar saturation regimes and show thermally activated behavior and gate voltage dependence. We fit the gate voltage dependent saturation mobility to a power law to extract the characteristic Meyer-Neldel (MN) energy, a measure of the width of the exponential distribution of localized states extending into the energy gap of the organic semiconductor. The MN energy is ∼78 and ∼28 meV for electrons and holes, respectively, which reflects a greater density of localized tail states for electrons than holes. This is consistent with the lower measured electron than hole mobility. For holes, the well-behaved linear regime allows for four-point probe measurement of the contact resistance independent mobility and separate characterization of the width of the localized density of states, yielding a consistent MN energy of 28 meV.

  14. Push-pull alkenes: structure and p-electron distribution

    Directory of Open Access Journals (Sweden)

    ERICH KLEINPETER

    2006-01-01

    Full Text Available Push-pull alkenes are substituted alkenes with one or two electron-donating substituents on one end of C=C double bond and with one or two electron-accepting substituents at the other end. Allowance for p-electron delocalization leads to the central C=C double bond becoming ever more polarized and with rising push-pull character, the p-bond order of this double bond is reduced and, conversely, the corresponding p-bond orders of the C–Don and C–Acc bonds are accordingly increased. This push-pull effect is of decisive influence on both the dynamic behavior and the chemical reactivity of this class of compounds and thus it is of considerable interest to both determine and to quantify the inherent push-pull effect. Previously, the barriers to rotation about the C=C, C–Don and/or C–Acc partial double bonds (DG±, as determined by dynamic NMR spectroscopy or the 13C chemical shift difference of the polarized C=C partial double bond (DdC=C were employed for this purpose. However, these parameters can have serious limitations, viz. the barriers can be immeasurable on the NMR timescale (either by being too high or too low; heavily-biased conformers are present, etc. or DdC=C behaves in a non-additive manner with respect to the combination of the four substituents. Hence, a general parameter to quantify the push-pull effect is not yet available. Ab initio MO calculations on a collection of compounds, together with NBO analysis, provided valuable information on the structure, bond energies, electron occupancies and bonding/antibonding interactions. In addition to DG±C=C (either experimentally determined or theoretically calculated and DdC=C, the bond length of the C=C partial double bond was also examined and it proved to be a reliable parameter to quantify the push-pull effect. Equally so, the quotient of the occupation numbers of the antibonding andbonding p orbitals of the central C=C partial double bond ( p*C=C/ pC=C could also be employed for

  15. Statistical mechanics of black holes

    International Nuclear Information System (INIS)

    Harms, B.; Leblanc, Y.

    1992-01-01

    We analyze the statistical mechanics of a gas of neutral and charged black holes. The microcanonical ensemble is the only possible approach to this system, and the equilibrium configuration is the one for which most of the energy is carried by a single black hole. Schwarzschild black holes are found to obey the statistical bootstrap condition. In all cases, the microcanonical temperature is identical to the Hawking temperature of the most massive black hole in the gas. U(1) charges in general break the bootstrap property. The problems of black-hole decay and of quantum coherence are also addressed

  16. Particle trapping in 3-D using a single fiber probe with an annular light distribution.

    Science.gov (United States)

    Taylor, R; Hnatovsky, C

    2003-10-20

    A single optical fiber probe has been used to trap a solid 2 ìm diameter glass bead in 3-D in water. Optical confinement in 2-D was produced by the annular light distribution emerging from a selectively chemically etched, tapered, hollow tipped metalized fiber probe. Confinement of the bead in 3-D was achieved by balancing an electrostatic force of attraction towards the tip and the optical scattering force pushing the particle away from the tip.

  17. Black Holes and Firewalls

    Science.gov (United States)

    Polchinski, Joseph

    2015-04-01

    Our modern understanding of space, time, matter, and even reality itself arose from the three great revolutions of the early twentieth century: special relativity, general relativity, and quantum mechanics. But a century later, this work is unfinished. Many deep connections have been discovered, but the full form of a unified theory incorporating all three principles is not known. Thought experiments and paradoxes have often played a key role in figuring out how to fit theories together. For the unification of general relativity and quantum mechanics, black holes have been an important arena. I will talk about the quantum mechanics of black holes, the information paradox, and the latest version of this paradox, the firewall. The firewall points to a conflict between our current theories of spacetime and of quantum mechanics. It may lead to a new understanding of how these are connected, perhaps based on quantum entanglement.

  18. Beyond the black hole

    International Nuclear Information System (INIS)

    Boslough, J.

    1985-01-01

    This book is about the life and work of Stephen Hawking. It traces the development of his theories about the universe and particularly black holes, in a biographical context. Hawking's lecture 'Is the end in sight for theoretical physics' is presented as an appendix. In this, he discusses the possibility of achieving a complete, consistent and unified theory of the physical interactions which would describe all possible observations. (U.K.)

  19. Bumpy black holes

    OpenAIRE

    Emparan, Roberto; Figueras, Pau; Martinez, Marina

    2014-01-01

    We study six-dimensional rotating black holes with bumpy horizons: these are topologically spherical, but the sizes of symmetric cycles on the horizon vary non-monotonically with the polar angle. We construct them numerically for the first three bumpy families, and follow them in solution space until they approach critical solutions with localized singularities on the horizon. We find strong evidence of the conical structures that have been conjectured to mediate the transitions to black ring...

  20. Internal structure of black holes

    International Nuclear Information System (INIS)

    Cvetic, Mirjam

    2013-01-01

    Full text: We review recent progress that sheds light on the internal structure of general black holes. We first summarize properties of general multi-charged rotating black holes both in four and five dimensions. We show that the asymptotic boundary conditions of these general asymptotically flat black holes can be modified such that a conformal symmetry emerges. These subtracted geometries preserve the thermodynamic properties of the original black holes and are of the Lifshitz type, thus describing 'a black hole in the asymptotically conical box'. Recent efforts employ solution generating techniques to construct interpolating geometries between the original black hole and their subtracted geometries. Upon lift to one dimension higher, these geometries lift to AdS 3 times a sphere, and thus provide a microscopic interpretation of the black hole entropy in terms of dual two-dimensional conformal field theory. (author)

  1. Black holes and holography

    International Nuclear Information System (INIS)

    Mathur, Samir D

    2012-01-01

    The idea of holography in gravity arose from the fact that the entropy of black holes is given by their surface area. The holography encountered in gauge/gravity duality has no such relation however; the boundary surface can be placed at an arbitrary location in AdS space and its area does not give the entropy of the bulk. The essential issues are also different between the two cases: in black holes we get Hawking radiation from the 'holographic surface' which leads to the information issue, while in gauge/gravity duality there is no such radiation. To resolve the information paradox we need to show that there are real degrees of freedom at the horizon of the hole; this is achieved by the fuzzball construction. In gauge/gravity duality we have instead a field theory defined on an abstract dual space; there are no gravitational degrees of freedom at the holographic boundary. It is important to understand the relations and differences between these two notions of holography to get a full understanding of the lessons from the information paradox.

  2. Probability of detection for bolt hole eddy current in extracted from service aircraft wing structures

    Science.gov (United States)

    Underhill, P. R.; Uemura, C.; Krause, T. W.

    2018-04-01

    Fatigue cracks are prone to develop around fasteners found in multi-layer aluminum structures on aging aircraft. Bolt hole eddy current (BHEC) is used for detection of cracks from within bolt holes after fastener removal. In support of qualification towards a target a90/95 (detect 90% of cracks of depth a, 95% of the time) of 0.76 mm (0.030"), a preliminary probability of detection (POD) study was performed to identify those parameters whose variation may keep a bolt hole inspection from attaining its goal. Parameters that were examined included variability in lift-off due to probe type, out-of-round holes, holes with diameters too large to permit surface-contact of the probe and mechanical damage to the holes, including burrs. The study examined the POD for BHEC of corner cracks in unfinished fastener holes extracted from service material. 68 EDM notches were introduced into two specimens of a horizontal stabilizer from a CC-130 Hercules aircraft. The fastener holes were inspected in the unfinished state, simulating potential inspection conditions, by 7 certified inspectors using a manual BHEC setup with an impedance plane display and also with one inspection conducted utilizing a BHEC automated C-Scan apparatus. While the standard detection limit of 1.27 mm (0.050") was achieved, given the a90/95 of 0.97 mm (0.039"), the target 0.76 mm (0.030") was not achieved. The work highlighted a number of areas where there was insufficient information to complete the qualification. Consequently, a number of recommendations were made. These included; development of a specification for minimum probe requirements; criteria for condition of the hole to be inspected, including out-of-roundness and presence of corrosion pits; statement of range of hole sizes; inspection frequency and data display for analysis.

  3. Constraints on the Primordial Black Hole Abundance from the First Advanced LIGO Observation Run Using the Stochastic Gravitational-Wave Background.

    Science.gov (United States)

    Wang, Sai; Wang, Yi-Fan; Huang, Qing-Guo; Li, Tjonnie G F

    2018-05-11

    Advanced LIGO's discovery of gravitational-wave events is stimulating extensive studies on the origin of binary black holes. Assuming that the gravitational-wave events can be explained by binary primordial black hole mergers, we utilize the upper limits on the stochastic gravitational-wave background given by Advanced LIGO as a new observational window to independently constrain the abundance of primordial black holes in dark matter. We show that Advanced LIGO's first observation run gives the best constraint on the primordial black hole abundance in the mass range 1M_{⊙}≲M_{PBH}≲100M_{⊙}, pushing the previous microlensing and dwarf galaxy dynamics constraints tighter by 1 order of magnitude. Moreover, we discuss the possibility to detect the stochastic gravitational-wave background from primordial black holes, in particular from subsolar mass primordial black holes, by Advanced LIGO in the near future.

  4. Constraints on the Primordial Black Hole Abundance from the First Advanced LIGO Observation Run Using the Stochastic Gravitational-Wave Background

    Science.gov (United States)

    Wang, Sai; Wang, Yi-Fan; Huang, Qing-Guo; Li, Tjonnie G. F.

    2018-05-01

    Advanced LIGO's discovery of gravitational-wave events is stimulating extensive studies on the origin of binary black holes. Assuming that the gravitational-wave events can be explained by binary primordial black hole mergers, we utilize the upper limits on the stochastic gravitational-wave background given by Advanced LIGO as a new observational window to independently constrain the abundance of primordial black holes in dark matter. We show that Advanced LIGO's first observation run gives the best constraint on the primordial black hole abundance in the mass range 1 M⊙≲MPBH≲100 M⊙, pushing the previous microlensing and dwarf galaxy dynamics constraints tighter by 1 order of magnitude. Moreover, we discuss the possibility to detect the stochastic gravitational-wave background from primordial black holes, in particular from subsolar mass primordial black holes, by Advanced LIGO in the near future.

  5. Monitoring of Au(iii) species in plants using a selective fluorescent probe.

    Science.gov (United States)

    Li, Zhen; Xu, Yuqing; Fu, Jie; Zhu, Hailiang; Qian, Yong

    2018-01-23

    A colorimetric and ratiometric probe with a push-pull chromophore dicyanoisophorone system, AuP, has been developed for the detection of Au(iii) species with highly sensitive and selective response to real-water samples and living tissues of Arabidopsis thaliana.

  6. Modelling the behaviour of the push-pull gel dosimeter

    International Nuclear Information System (INIS)

    Bosi, S.G.; Davies, J.B.; Gorjiara, T.; Baldock, C.

    2010-01-01

    Full text: Recent development of a gel dosimeter based on the radiobleaching pigment, genipin, allows development of a new 3D optically scanned gel dosimeter-the p ush-pull g el. This gel would contain two spectrally complementary pigments, one which darkens with dose and another (e.g. genipin) which bleaches. The two pigments deal separately with the high and low dose ends of the dosimeter's dynamic range. The bleaching pigment would be optimised for high sensitivity and the darkening pigment for low. Employing dual pigments, optimised independently, relaxes the need for compromise between sensitivity at low dose and accuracy at high dose. Such a gel, after exposure, would be read using two successive optical CT scans, at two different wavelengths. The reduction in sensitivity of the darkening pigment (allowed by the use of push-pull) would reduce the occurrence of regions of high optical attenuation which can generate optical CT artefacts. Simulated optical CT reconstructions of the optical density map (Fig. La) scanned at the darkening pigment wavelength of a hypothetical push-pull gel, confirms the reduction in susceptibility to artefacts. Fig. I b shows a profile through the map with no stray light added. The centre of the profile in Fig. I d shows a cupping artefact produced by 10 ppm of stray light. The similarity of Fig. Ic and b show that a 30% sensitivity reduction allowed by push-pull, renders the artefact negligible. This paper presents the results of' these simulations of a push-pull gel scanned using optical CT and also some results of experiments with genipin gel. (author)

  7. Gender Inequality and Emigration: Push factor or Selection process?

    OpenAIRE

    Baudassé, Thierry; Bazillier, Rémi

    2012-01-01

    Our objective in this research is to provide empirical evidence relating to the linkages between gender equality and international emigration. Two theoretical hypotheses can be made for the purpose of analyzing such linkages. The fi rst is that gender inequality in origin countries could be a push factor for women. The second one is that gender inequality may create a \\gender bias" in the selection of migrants within a household or a community. An improvement of gender equality would then inc...

  8. Dielectric films for solar and laser-pushed lightsails

    International Nuclear Information System (INIS)

    Landis, Geoffrey A.

    2000-01-01

    This project analyzed the potential use of dielectric thin films for solar and laser sails. Such light-pushed sails allow the possibility of fuel-free propulsion in space. This makes possible missions of extremely high delta-V, potentially as high as 30,000 km/sec (0.1c), which is required for a fly-by mission to a nearby star

  9. Gamma-ray spectrometry applied to down-hole logging

    International Nuclear Information System (INIS)

    Dumesnil, P.; Umiastowsky, K.

    1983-11-01

    Gamma-ray spectrometry permits to improve the accuracy of natural gamma, gamma-gamma and neutron-gamma geophysical measurements. The probe developed at Centre d'Etudes Nucleaires de Saclay allows down-hole gamma-ray spectrometry. Among others, this probe can be applied to the uranium content determination by selective natural gamma method, down-hole determination of the ash content in the coal by gamma-gamma selective method and elemental analysis by neutron-gamma method. For the calibration and an exact interpretation of the measurements it is important to know the gamma-ray and neutron characteristics of the different kinds of rocks considered as probabilistic variables

  10. Hole polaron-polaron interaction in transition metal oxides and its limit to p-type doping

    Science.gov (United States)

    Chen, Shiyou; Wang, Lin-Wang

    2014-03-01

    Traditionally the origin of the poor p-type conductivity in some transition metal oxides (TMOs) was attributed to the limited hole concentration: the charge-compensating donor defects, such as oxygen vacancies and cation interstitials, can form spontaneously as the Fermi energy shifts down to near the valence band maximum. Besides the thermodynamic limit to the hole concentration, the limit to the hole mobility can be another possible reason, e.g., the hole carrier can form self-trapped polarons with very low carrier mobility. Although isolated hole polarons had been found in some TMOs, the polaron-polaron interaction is not well-studied. Here we show that in TMOs such as TiO2 and V2O5, the hole polarons prefer to bind with each other to form bipolarons, which are more stable than free hole carriers or separated polarons. This pushes the hole states upward into the conduction band and traps the holes. The rise of the Fermi energy suppresses the spontaneous formation of the charge-compensating donor defects, so the conventional mechanism becomes ineffective. Since it can happen in the impurity-free TMO lattices, independent of any extrinsic dopant, it acts as an intrinsic and general limit to the p-type conductivity in these TMOs. This material is based upon work performed by the JCAP, a US DOE Energy Innovation Hub, the NSFC (No. 61106087 and 91233121) and special funds for major state basic research (No. 2012CB921401).

  11. An Extra Push from Entrance-Channel Effects

    International Nuclear Information System (INIS)

    Grar, Nabila; Rowley, Neil

    2006-01-01

    The fusion probability for heavy symmetric systems is known to show certain very specific features. Apart from the large variance of the fusion barrier distribution, it is found that the energy at which the s-wave transmission is 0.5 is shifted to an energy significantly higher than the nominal (e.g. Bass) Coulomb barrier. This last feature is referred to in the literature as the 'extra push' effect. Many models have been devised to explain the origin of these findings. It is worth noting, however, that despite the extra push, the capture cross section is still greatly enhanced at the very lowest energies. This fact cannot be explained within the framework of macroscopic theories involving conditional saddle points or frictional forces. We have performed full coupled-channel calculations for heavy, symmetric systems treating correctly the long-range Coulomb excitations of the collective quadrupole- and octupole-phonon states in the target and projectile. The results obtained show that the extra push and the overall shape of the fusion probability are simply explained by these entrance-channel effects

  12. Push Off 2000 : new oilfield safety device catching on

    Energy Technology Data Exchange (ETDEWEB)

    Mowers, J.

    2006-12-15

    Fuel gas scrubbers use production gas to operate oil batteries, well separators, dehydrators, compressors, and pneumatic and pressure controls. Once an internal float gets stuck, production is stopped. The Push Off 2000 is a new safety device for fuel gas scrubbers which allows operators to easily dislodge a stuck internal float by activating the tool, which is mounted on top of the vessel. The device was developed after an operator suffered burns from a flash explosion that occurred after using a hammer to strike the fuel gas scrubber. The hammer method is the usual method of dealing with stuck internal floats, and can also jeopardize the integrity of the vessel, releasing gas or liquid hydrocarbons into the environment. The Push Off 2000 is expected to reduce costly facility downtime and increase revenue generating production time. Over 50 oil and gas companies have the Push Off 2000 device installed on fuel gas scrubber units at their facilities, and have recognized the safety and economic merits of the tool. The patented device has been approved by the Alberta Boilers Safety Association, the British Columbia Boiler and Elevator Safety Branch, and the Saskatchewan Boiler and Pressure Vessel Safety Unit. 1 fig.

  13. Modeling and Simulation of Two Wheelchair Accessories for Pushing Doors.

    Science.gov (United States)

    Abdullah, Soran Jalal; Shaikh Mohammed, Javeed

    2017-03-27

    Independent mobility is vital to individuals of all ages, and wheelchairs have proven to be great personal mobility devices. The tasks of opening and navigating through a door are trivial for healthy people, while the same tasks could be difficult for some wheelchair users. A wide range of intelligent wheelchair controllers and systems, robotic arms, or manipulator attachments integrated with wheelchairs have been developed for various applications, including manipulating door knobs. Unfortunately, the intelligent wheelchairs and robotic attachments are not widely available as commercial products. Therefore, the current manuscript presents the modeling and simulation of a novel but simple technology in the form of a passive wheelchair accessory (straight, arm-like with a single wheel, and arc-shaped with multiple wheels) for pushing doors open from a wheelchair. From the simulations using different wheel shapes and sizes, it was found that the arc-shaped accessory could push open the doors faster and with almost half the required force as compared to the arm-like accessory. Also, smaller spherical wheels were found to be best in terms of reaction forces on the wheels. Prototypes based on the arc-shaped accessory design will be manufactured and evaluated for pushing doors open and dodging or gliding other obstacles.

  14. 49 CFR 220.49 - Radio communication used in shoving, backing or pushing movements.

    Science.gov (United States)

    2010-10-01

    ... pushing movements. 220.49 Section 220.49 Transportation Other Regulations Relating to Transportation... Wireless Communication Procedures § 220.49 Radio communication used in shoving, backing or pushing movements. When radio communication is used in connection with the shoving, backing or pushing of a train...

  15. Manual handling: differences in perceived effort, success rate and kinematics between three different pushing techniques.

    Science.gov (United States)

    Varcin, Lynn; Claus, Andrew; van den Hoorn, Wolbert; Hodges, Paul

    2015-01-01

    This study examined the perceived effort, success rates and kinematics for three push strategies in a simulated lateral patient transfer (horizontal slide). Thirteen healthy subjects (four males) completed three repetition pushing loads of 6, 10 and 14 kg in random order; with a spontaneous push strategy, then with a straight-back bent-knees (squat) strategy and the preparatory pelvic movement ('rockback') strategy in random order. Perceived effort and kinematic parameters measured at the onset of movement and at maximum push excursion were compared between strategies and between loads with repeated measures ANOVA. The spontaneous and 'rockback' strategies achieved the pushing task with less perceived effort across all loads than the squat push (P pushing the 14 kg load using a squat strategy, which contrasted with 12/13 participants when the spontaneous strategy or the 'rockback' strategy was used. Forward movement of the pelvis and forward trunk inclination may be positively associated with lower perceived effort in the push task. Practitioner Summary: In a manual-handling task that simulated a lateral patient transfer (horizontal slide), perceived effort and success rates of three push strategies were compared. A straight-back bent-knees push (squat) strategy demonstrated greater perceived effort and lower success rates than a spontaneous push strategy, or a push strategy with preparatory 'rockback' pelvic movement.

  16. Effects of pushing techniques during the second stage of labor: A randomized controlled trial.

    Science.gov (United States)

    Koyucu, Refika Genç; Demirci, Nurdan

    2017-10-01

    Spontaneous pushing is a method that is used in the management of the second stage of labor and suggested to be more physiological for the mother and infant. The present study aims to evaluate the effects of pushing techniques on the mother and newborn. This randomized prospective study was performed between June 2013-March 2014 in a tertiary maternity clinic in Istanbul. 80 low risk, nulliparous cases were randomized to pushing groups. Valsalva pushing group was told to hold their breath while pushing. No visual-verbal instructions were given to spontaneous pushing group and they were encouraged to push without preventing respiration. Demographic data, second stage period, perineal laceration rates, fetal heart rate patterns, presence of meconium stained amniotic liquid, newborn APGAR scores, POP-Q examination and Q-tip test results were evaluated in these cases. The second stage of labor was significantly longer with spontaneous pushing. Decrease in Hb levels in valsalva pushing group was determined to be higher than spontaneous pushing group. An increased urethral mobility was observed in valsalva pushing group. Although the duration of the second stage of labor was longer compared to valsalva pushing technique, women were able to give birth without requiring any verbal or visual instruction, without exceeding the limit value of two hours and without affecting fetal wellness and neonatal results. Copyright © 2017. Published by Elsevier B.V.

  17. Contribution of limb momentum to power transfer in athletic wheelchair pushing.

    Science.gov (United States)

    Masson, G; Bégin, M-A; Lopez Poncelas, M; Pelletier, S-K; Lessard, J-L; Laroche, J; Berrigan, F; Langelier, E; Smeesters, C; Rancourt, D

    2016-09-06

    Pushing capacity is a key parameter in athletic racing wheelchair performance. This study estimated the potential contribution of upper limb momentum to pushing. The question is relevant since it may affect the training strategy adopted by an athlete. A muscle-free Lagrangian dynamic model of the upper limb segments was developed and theoretical predictions of power transfer to the wheelchair were computed during the push phase. Results show that limb momentum capacity for pushing can be in the order of 40J per push cycle at 10m/s, but it varies with the specific pushing range chosen by the athlete. Although use of momentum could certainly help an athlete improve performance, quantifying the actual contribution of limb momentum to pushing is not trivial. A preliminary experimental investigation on an ergometer, along with a simplified model of the upper limb, suggests that momentum is not the sole contributor to power transfer to a wheelchair. Muscles substantially contribute to pushing, even at high speeds. Moreover, an optimal pushing range is challenging to find since it most likely differs if an athlete chooses a limb momentum pushing strategy versus a muscular exertion pushing strategy, or both at the same time. The study emphasizes the importance of controlling pushing range, although one should optimize it while also taking the dynamics of the recovery period into account. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Tidal stripping of stars near supermassive black holes

    Directory of Open Access Journals (Sweden)

    Blandford R.

    2012-12-01

    Full Text Available In a binary system composed of a supermassive black hole and a star orbiting the hole in an equatorial, circular orbit, the stellar orbit will shrink due to the action of gravitational radiation, until the star fills its Roche lobe outside the Innermost Stable Circular Orbit (ISCO of the hole or plunges into the hole. In the former case, gas will flow through the inner Lagrange point (L1 to the hole. If this tidal stripping process happens on a time scale faster than the thermal time scale but slower than the dynamical time scale, the entropy as a function of the interior mass is conserved. The star will evolve adiabatically, and, in most cases, will recede from the hole while filling its Roche lobe. We calculate how the stellar equilibrium properties change, which determines how the stellar orbital period and mass-transfer rate change through the “Roche evolution” for various types of stars in the relativistic regime. We envisage that the mass stream eventually hits the accretion disc, where it forms a hot spot orbiting the hole and may ultimately modulate the luminosity with the stellar orbital frequency. The ultimate goal is to probe the mass and spin of the hole and provide a test of general relativity in the strong-field regime from the resultant quasi-periodic signals. The observability of such a modulation is discussed along with a possible interpretation of an intermittent 1 hour period in the X-ray emission of RE J1034+ 396.

  19. Quantum horizon fluctuations of an evaporating black hole

    International Nuclear Information System (INIS)

    Roura, Albert

    2007-01-01

    The quantum fluctuations of a black hole spacetime are studied within a low-energy effective field theory approach to quantum gravity. Our approach accounts for both intrinsic metric fluctuations and those induced by matter fields interacting with the gravitational field. Here we will concentrate on spherically symmetric fluctuations of the black hole horizon. Our results suggest that for a sufficiently massive evaporating black hole, fluctuations can accumulate over time and become significant well before reaching Planckian scales. In addition, we provide the sketch of a proof that the symmetrized two-point function of the stress-tensor operator smeared over a null hypersurface is actually divergent and discuss the implications for the analysis of horizon fluctuations. Finally, a natural way to probe quantum metric fluctuations near the horizon is briefly described

  20. Black holes a laboratory for testing strong gravity

    CERN Document Server

    Bambi, Cosimo

    2017-01-01

    This textbook introduces the current astrophysical observations of black holes, and discusses the leading techniques to study the strong gravity region around these objects with electromagnetic radiation. More importantly, it provides the basic tools for writing an astrophysical code and testing the Kerr paradigm. Astrophysical black holes are an ideal laboratory for testing strong gravity. According to general relativity, the spacetime geometry around these objects should be well described by the Kerr solution. The electromagnetic radiation emitted by the gas in the inner part of the accretion disk can probe the metric of the strong gravity region and test the Kerr black hole hypothesis. With exercises and examples in each chapter, as well as calculations and analytical details in the appendix, the book is especially useful to the beginners or graduate students who are familiar with general relativity while they do not have any background in astronomy or astrophysics.

  1. Quantum hair and the string-black hole correspondence

    CERN Document Server

    Veneziano, Gabriele

    2013-01-01

    We consider a thought experiment in which an energetic massless string probes a "stringhole" (a heavy string lying on the correspondence curve between strings and black holes) at large enough impact parameter for the regime to be under theoretical control. The corresponding, explicitly unitary, $S$-matrix turns out to be perturbatively sensitive to the microstate of the stringhole: in particular, at leading order in $l_s/b$, it depends on a projection of the stringhole's Lorentz-contracted quadrupole moment. The string-black hole correspondence is therefore violated if one assumes quantum hair to be exponentially suppressed as a function of black-hole entropy. Implications for the information paradox are briefly discussed.

  2. Microscopic Calabi-Yau black holes in string theory

    International Nuclear Information System (INIS)

    Ansari, Saeid

    2011-01-01

    In this thesis we study microscopic aspects of Calabi-Yau black holes in string theory. We compute the absorption cross-section of the space-time massless scalars by the worldvolume of D2-branes, wrapped on the S 2 of an AdS 2 x S 2 x CY 3 geometry of a fourdimensional D4-D0 Calabi-Yau black hole. The D2-brane can also have a generic D0 probe-brane charge. However, we restrict ourselves to D2-branes with small D0-charge so that the perturbation theory is applicable. According to the proposed AdS 2 /QM correspondence the candidate for the dual theory is the quantum mechanics of a set of probe D0-branes in the AdS 2 geometry. For small but non-zero probe D0-charge we find the quantum mechanical absorption cross-section seen by an asymptotic anti-de Sitter observer. We repeat the calculations for vanishing probe D0-charge as well and discuss our result by comparing with the classical absorption cross-section. In other project, for a given fourdimensional Calabi-Yau black hole with generic D6-D4-D2-D0 charges we identify a set of supersymmetric branes, which are static or stationary in the global coordinates, of the corresponding eleven-dimensional near horizon geometry. The set of these BPS states, which include the branes partially or fully wrap the horizon, should play a role in understanding the partition function of black holes with D6-charge. (orig.)

  3. Microscopic Calabi-Yau black holes in string theory

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Saeid

    2011-07-22

    In this thesis we study microscopic aspects of Calabi-Yau black holes in string theory. We compute the absorption cross-section of the space-time massless scalars by the worldvolume of D2-branes, wrapped on the S{sup 2} of an AdS{sub 2} x S{sup 2} x CY{sub 3} geometry of a fourdimensional D4-D0 Calabi-Yau black hole. The D2-brane can also have a generic D0 probe-brane charge. However, we restrict ourselves to D2-branes with small D0-charge so that the perturbation theory is applicable. According to the proposed AdS{sub 2}/QM correspondence the candidate for the dual theory is the quantum mechanics of a set of probe D0-branes in the AdS{sub 2} geometry. For small but non-zero probe D0-charge we find the quantum mechanical absorption cross-section seen by an asymptotic anti-de Sitter observer. We repeat the calculations for vanishing probe D0-charge as well and discuss our result by comparing with the classical absorption cross-section. In other project, for a given fourdimensional Calabi-Yau black hole with generic D6-D4-D2-D0 charges we identify a set of supersymmetric branes, which are static or stationary in the global coordinates, of the corresponding eleven-dimensional near horizon geometry. The set of these BPS states, which include the branes partially or fully wrap the horizon, should play a role in understanding the partition function of black holes with D6-charge. (orig.)

  4. Dynamic pressure probe response tests for robust measurements in periodic flows close to probe resonating frequency

    Science.gov (United States)

    Ceyhun Şahin, Fatma; Schiffmann, Jürg

    2018-02-01

    A single-hole probe was designed to measure steady and periodic flows with high fluctuation amplitudes and with minimal flow intrusion. Because of its high aspect ratio, estimations showed that the probe resonates at a frequency two orders of magnitude lower than the fast response sensor cut-off frequencies. The high fluctuation amplitudes cause a non-linear behavior of the probe and available models are neither adequate for a quantitative estimation of the resonating frequencies nor for predicting the system damping. Instead, a non-linear data correction procedure based on individual transfer functions defined for each harmonic contribution is introduced for pneumatic probes that allows to extend their operating range beyond the resonating frequencies and linear dynamics. This data correction procedure was assessed on a miniature single-hole probe of 0.35 mm inner diameter which was designed to measure flow speed and direction. For the reliable use of such a probe in periodic flows, its frequency response was reproduced with a siren disk, which allows exciting the probe up to 10 kHz with peak-to-peak amplitudes ranging between 20%-170% of the absolute mean pressure. The effect of the probe interior design on the phase lag and amplitude distortion in periodic flow measurements was investigated on probes with similar inner diameters and different lengths or similar aspect ratios (L/D) and different total interior volumes. The results suggest that while the tube length consistently sets the resonance frequency, the internal total volume affects the non-linear dynamic response in terms of varying gain functions. A detailed analysis of the introduced calibration methodology shows that the goodness of the reconstructed data compared to the reference data is above 75% for fundamental frequencies up to twice the probe resonance frequency. The results clearly suggest that the introduced procedure is adequate to capture non-linear pneumatic probe dynamics and to

  5. Statistical black-hole thermodynamics

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1975-01-01

    Traditional methods from statistical thermodynamics, with appropriate modifications, are used to study several problems in black-hole thermodynamics. Jaynes's maximum-uncertainty method for computing probabilities is used to show that the earlier-formulated generalized second law is respected in statistically averaged form in the process of spontaneous radiation by a Kerr black hole discovered by Hawking, and also in the case of a Schwarzschild hole immersed in a bath of black-body radiation, however cold. The generalized second law is used to motivate a maximum-entropy principle for determining the equilibrium probability distribution for a system containing a black hole. As an application we derive the distribution for the radiation in equilibrium with a Kerr hole (it is found to agree with what would be expected from Hawking's results) and the form of the associated distribution among Kerr black-hole solution states of definite mass. The same results are shown to follow from a statistical interpretation of the concept of black-hole entropy as the natural logarithm of the number of possible interior configurations that are compatible with the given exterior black-hole state. We also formulate a Jaynes-type maximum-uncertainty principle for black holes, and apply it to obtain the probability distribution among Kerr solution states for an isolated radiating Kerr hole

  6. Black Hole Area Quantization rule from Black Hole Mass Fluctuations

    OpenAIRE

    Schiffer, Marcelo

    2016-01-01

    We calculate the black hole mass distribution function that follows from the random emission of quanta by Hawking radiation and with this function we calculate the black hole mass fluctuation. From a complete different perspective we regard the black hole as quantum mechanical system with a quantized event horizon area and transition probabilities among the various energy levels and then calculate the mass dispersion. It turns out that there is a perfect agreement between the statistical and ...

  7. Non-Gaussian ground-state deformations near a black-hole singularity

    Science.gov (United States)

    Hofmann, Stefan; Schneider, Marc

    2017-03-01

    The singularity theorem by Hawking and Penrose qualifies Schwarzschild black holes as geodesic incomplete space-times. Albeit this is a mathematically rigorous statement, it requires an operational framework that allows us to probe the spacelike singularity via a measurement process. Any such framework necessarily has to be based on quantum theory. As a consequence, the notion of classical completeness needs to be adapted to situations where the only adequate description is in terms of quantum fields in dynamical space-times. It is shown that Schwarzschild black holes turn out to be complete when probed by self-interacting quantum fields in the ground state and in excited states. The measure for populating quantum fields on hypersurfaces in the vicinity of the black-hole singularity goes to zero towards the singularity. This statement is robust under non-Gaussian deformations of and excitations relative to the ground state. The physical relevance of different completeness concepts for black holes is discussed.

  8. Electromagnetic microscope compared with a conventional pulsed eddy-current probe

    Science.gov (United States)

    Podney, Walter N.

    1998-03-01

    A superconductive probe presently can detect a crack at a rivet hole that is two to three times smaller than the smallest crack detectable by a conventional probe. As the technology matures and noise resolution approaches a limit set by SQUIDS, approximately 1 fH, it will enable detecting submillimeter cracks down to approximately 15 mm.

  9. Effect of External Loading on Force and Power Production During Plyometric Push-ups.

    Science.gov (United States)

    Hinshaw, Taylour J; Stephenson, Mitchell L; Sha, Zhanxin; Dai, Boyi

    2018-04-01

    Hinshaw, TJ, Stephenson, ML, Sha, Z, and Dai, B. Effect of external loading on force and power production during plyometric push-ups. J Strength Cond Res 32(4): 1099-1108, 2018-One common exercise to train upper-body strength and power is the push-up. Training at the loads that would produce the greatest power is an effective way to increase peak power. The purpose of the current study was to quantify the changes in peak force, peak power, and peak velocity among a modified plyometric push-up and plyometric push-ups with or without external loading in physically active young adults. Eighteen male and 17 female participants completed 4 push-ups: (a) modified plyometric push-up on the knees, (b) plyometric push-up without external loading, (c) plyometric push-up with an external load of 5% of body weight, and (d) plyometric push-up with an external load of 10% of body weight. Two force platforms were set up to collect vertical ground reaction forces at the hands and feet. The modified plyometric push-up demonstrated the lowest force, power, and velocity (5.4≥ Cohen's dz ≥1.2). Peak force and force at peak velocity increased (3.8≥ Cohen's dz ≥0.3) and peak velocity and velocity at peak power decreased (1.4≥ Cohen's dz ≥0.8) for the push-up without external loading compared with the 2 push-ups with external loading. No significant differences were observed for peak power among the push-ups with or without external loading (0.4≥ Cohen's dz ≥0.1). Although peak power is similar with or without external loading, push-ups without external loading may be more beneficial for a quick movement, and push-ups with external loading may be more beneficial for a greater force production.

  10. Mobile Game Probes

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2006-01-01

    This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....

  11. Artificial black holes

    CERN Document Server

    Visser, Matt; Volovik, Grigory E

    2009-01-01

    Physicists are pondering on the possibility of simulating black holes in the laboratory by means of various "analog models". These analog models, typically based on condensed matter physics, can be used to help us understand general relativity (Einstein's gravity); conversely, abstract techniques developed in general relativity can sometimes be used to help us understand certain aspects of condensed matter physics. This book contains 13 chapters - written by experts in general relativity, particle physics, and condensed matter physics - that explore various aspects of this two-way traffic.

  12. The Antarctic ozone hole

    International Nuclear Information System (INIS)

    Jones, Anna E

    2008-01-01

    Since the mid 1970s, the ozone layer over Antarctica has experienced massive destruction during every spring. In this article, we will consider the atmosphere, and what ozone and the ozone layer actually are. We explore the chemistry responsible for the ozone destruction, and learn about why conditions favour ozone destruction over Antarctica. For the historical perspective, the events leading up to the discovery of the 'hole' are presented, as well as the response from the international community and the measures taken to protect the ozone layer now and into the future

  13. Thermal BEC Black Holes

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2015-10-01

    Full Text Available We review some features of Bose–Einstein condensate (BEC models of black holes obtained by means of the horizon wave function formalism. We consider the Klein–Gordon equation for a toy graviton field coupled to a static matter current in a spherically-symmetric setup. The classical field reproduces the Newtonian potential generated by the matter source, while the corresponding quantum state is given by a coherent superposition of scalar modes with a continuous occupation number. An attractive self-interaction is needed for bound states to form, the case in which one finds that (approximately one mode is allowed, and the system of N bosons can be self-confined in a volume of the size of the Schwarzschild radius. The horizon wave function formalism is then used to show that the radius of such a system corresponds to a proper horizon. The uncertainty in the size of the horizon is related to the typical energy of Hawking modes: it decreases with the increasing of the black hole mass (larger number of gravitons, resulting in agreement with the semiclassical calculations and which does not hold for a single very massive particle. The spectrum of these systems has two components: a discrete ground state of energy m (the bosons forming the black hole and a continuous spectrum with energy ω > m (representing the Hawking radiation and modeled with a Planckian distribution at the expected Hawking temperature. Assuming the main effect of the internal scatterings is the Hawking radiation, the N-particle state can be collectively described by a single-particle wave-function given by a superposition of a total ground state with energy M = Nm and Entropy 2015, 17 6894 a Planckian distribution for E > M at the same Hawking temperature. This can be used to compute the partition function and to find the usual area law for the entropy, with a logarithmic correction related to the Hawking component. The backreaction of modes with ω > m is also shown to reduce

  14. Quantum effects in black holes

    International Nuclear Information System (INIS)

    Frolov, V.P.

    1979-01-01

    A strict definition of black holes is presented and some properties with regard to their mass are enumerated. The Hawking quantum effect - the effect of vacuum instability in the black hole gravitational field, as a result of shich the black hole radiates as a heated body is analyzed. It is shown that in order to obtain results on the black hole radiation it is sufficient to predetermine the in-vacuum state at a time moment in the past, when the collapsing body has a large size, and its gravitational field can be neglected. The causes and the place of particle production by the black hole, and also the space-time inside the black hole, are considered

  15. Particle creation by black holes

    International Nuclear Information System (INIS)

    Hawking, S.W.

    1975-01-01

    In the classical theory black holes can only absorb and not emit particles. However it is shown that quantum mechanical effects cause black holes to create and emit particles. This thermal emission leads to a slow decrease in the mass of the black hole and to its eventual disappearance: any primordial black hole of mass less than about 10 15 g would have evaporated by now. Although these quantum effects violate the classical law that the area of the event horizon of a black hole cannot decrease, there remains a Generalized Second Law: S + 1/4 A never decreases where S is the entropy of matter outside black holes and A is the sum of the surface areas of the event horizons. This shows that gravitational collapse converts the baryons and leptons in the collapsing body into entropy. It is tempting to speculate that this might be the reason why the Universe contains so much entropy per baryon. (orig.) [de

  16. Black Hole's 1/N Hair

    CERN Document Server

    Dvali, Gia

    2013-01-01

    According to the standard view classically black holes carry no hair, whereas quantum hair is at best exponentially weak. We show that suppression of hair is an artifact of the semi-classical treatment and that in the quantum picture hair appears as an inverse mass-square effect. Such hair is predicted in the microscopic quantum description in which a black hole represents a self-sustained leaky Bose-condensate of N soft gravitons. In this picture the Hawking radiation is the quantum depletion of the condensate. Within this picture we show that quantum black hole physics is fully compatible with continuous global symmetries and that global hair appears with the strength B/N, where B is the global charge swallowed by the black hole. For large charge this hair has dramatic effect on black hole dynamics. Our findings can have interesting astrophysical consequences, such as existence of black holes with large detectable baryonic and leptonic numbers.

  17. What is a black hole

    International Nuclear Information System (INIS)

    Tipler, F.J.

    1979-01-01

    A definition of a black hole is proposed that should work in any stably causal space-time. This is that a black hole is the closure of the smaller future set that contains all noncosmological trapped surfaces and which has its boundary generated by null geodesic segments that are boundary generators of TIPs. This allows precise definitions of cosmic censorship and white holes. (UK)

  18. Black Holes in Higher Dimensions

    Directory of Open Access Journals (Sweden)

    Reall Harvey S.

    2008-09-01

    Full Text Available We review black-hole solutions of higher-dimensional vacuum gravity and higher-dimensional supergravity theories. The discussion of vacuum gravity is pedagogical, with detailed reviews of Myers–Perry solutions, black rings, and solution-generating techniques. We discuss black-hole solutions of maximal supergravity theories, including black holes in anti-de Sitter space. General results and open problems are discussed throughout.

  19. Effect of spontaneous pushing versus Valsalva pushing in the second stage of labour on mother and fetus: a systematic review of randomised trials.

    Science.gov (United States)

    Prins, M; Boxem, J; Lucas, C; Hutton, E

    2011-05-01

    To critically evaluate any benefit or harm for the mother and her baby of Valsalva pushing versus spontaneous pushing in the second stage of labour. Electronic databases from MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials were systematically searched (last search May 2010). The reference lists of retrieved studies were searched by hand and an internet hand search of master theses and dissertations was performed. No date or language restriction was used. Randomised controlled trials that compared instructed pushing with spontaneous pushing in the second stage of labour were considered. Studies were evaluated independently for methodological quality and appropriateness for inclusion by two authors (MP and JB). The primary outcome was instrumental/operative delivery. Other outcomes were length of labour, any perineal repair, bladder function, maternal satisfaction. Infant outcomes included low Apgar score pushing technique (three studies; 425 women; mean difference 18.59 minutes; 95% CI 0.46-36.73 minutes). Neonatal outcomes did not differ significantly. Urodynamic factors measured 3 months postpartum were negatively affected by Valsalva pushing. Measures of first urge to void and bladder capacity were decreased (one study; 128 women; mean difference respectively 41.50 ml, 95% CI 8.40-74.60, and 54.60 ml, 95% CI 13.31-95.89). The evidence from our review does not support the routine use of Valsalva pushing in the second stage of labour. The Valsalva pushing method has a negative effect on urodynamic factors according to one study. The duration of the second stage of labour is shorter with Valsalva pushing but the clinical significance of this finding is uncertain. The primary studies are sparse, diverse and some flawed. Further research seems warranted. In the mean time supporting spontaneous pushing and encouraging women to choose their own method of pushing should be accepted as best clinical practice. © 2011 The Authors BJOG An

  20. Psychophysical basis for maximum pushing and pulling forces: A review and recommendations.

    Science.gov (United States)

    Garg, Arun; Waters, Thomas; Kapellusch, Jay; Karwowski, Waldemar

    2014-03-01

    The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers. At present it is not clear whether pushing or pulling should be favored. Similarly, it is not clear what handle heights would be optimal for pushing and pulling. Epidemiological studies are needed to determine relationships between psychophysically determined maximum acceptable pushing and pulling forces and risk of musculoskeletal injuries, in particular to low back and shoulders.

  1. Acceleration of black hole universe

    Science.gov (United States)

    Zhang, T. X.; Frederick, C.

    2014-01-01

    Recently, Zhang slightly modified the standard big bang theory and developed a new cosmological model called black hole universe, which is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This paper investigates acceleration of the black hole universe and provides an alternative explanation for the redshift and luminosity distance measurements of type Ia supernovae. The results indicate that the black hole universe accelerates its expansion when it accretes the ambient matter in an increasing rate. In other words, i.e., when the second-order derivative of the mass of the black hole universe with respect to the time is positive . For a constant deceleration parameter , we can perfectly explain the type Ia supernova measurements with the reduced chi-square to be very close to unity, χ red˜1.0012. The expansion and acceleration of black hole universe are driven by external energy.

  2. On black hole horizon fluctuations

    International Nuclear Information System (INIS)

    Tuchin, K.L.

    1999-01-01

    A study of the high angular momentum particles 'atmosphere' near the Schwarzschild black hole horizon suggested that strong gravitational interactions occur at invariant distance of the order of 3 √M [2]. We present a generalization of this result to the Kerr-Newman black hole case. It is shown that the larger charge and angular momentum black hole bears, the larger invariant distance at which strong gravitational interactions occur becomes. This invariant distance is of order 3 √((r + 2 )/((r + - r - ))). This implies that the Planckian structure of the Hawking radiation of extreme black holes is completely broken

  3. Black holes and the multiverse

    International Nuclear Information System (INIS)

    Garriga, Jaume; Vilenkin, Alexander; Zhang, Jun

    2016-01-01

    Vacuum bubbles may nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the bubbles quickly dissipate their kinetic energy; they come to rest with respect to the Hubble flow and eventually form black holes. The fate of the bubble itself depends on the resulting black hole mass. If the mass is smaller than a certain critical value, the bubble collapses to a singularity. Otherwise, the bubble interior inflates, forming a baby universe, which is connected to the exterior FRW region by a wormhole. A similar black hole formation mechanism operates for spherical domain walls nucleating during inflation. As an illustrative example, we studied the black hole mass spectrum in the domain wall scenario, assuming that domain walls interact with matter only gravitationally. Our results indicate that, depending on the model parameters, black holes produced in this scenario can have significant astrophysical effects and can even serve as dark matter or as seeds for supermassive black holes. The mechanism of black hole formation described in this paper is very generic and has important implications for the global structure of the universe. Baby universes inside super-critical black holes inflate eternally and nucleate bubbles of all vacua allowed by the underlying particle physics. The resulting multiverse has a very non-trivial spacetime structure, with a multitude of eternally inflating regions connected by wormholes. If a black hole population with the predicted mass spectrum is discovered, it could be regarded as evidence for inflation and for the existence of a multiverse

  4. Black holes and the multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Garriga, Jaume [Departament de Fisica Fonamental i Institut de Ciencies del Cosmos, Universitat de Barcelona, Marti i Franques, 1, Barcelona, 08028 Spain (Spain); Vilenkin, Alexander; Zhang, Jun, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu, E-mail: jun.zhang@tufts.edu [Institute of Cosmology, Tufts University, 574 Boston Ave, Medford, MA, 02155 (United States)

    2016-02-01

    Vacuum bubbles may nucleate and expand during the inflationary epoch in the early universe. After inflation ends, the bubbles quickly dissipate their kinetic energy; they come to rest with respect to the Hubble flow and eventually form black holes. The fate of the bubble itself depends on the resulting black hole mass. If the mass is smaller than a certain critical value, the bubble collapses to a singularity. Otherwise, the bubble interior inflates, forming a baby universe, which is connected to the exterior FRW region by a wormhole. A similar black hole formation mechanism operates for spherical domain walls nucleating during inflation. As an illustrative example, we studied the black hole mass spectrum in the domain wall scenario, assuming that domain walls interact with matter only gravitationally. Our results indicate that, depending on the model parameters, black holes produced in this scenario can have significant astrophysical effects and can even serve as dark matter or as seeds for supermassive black holes. The mechanism of black hole formation described in this paper is very generic and has important implications for the global structure of the universe. Baby universes inside super-critical black holes inflate eternally and nucleate bubbles of all vacua allowed by the underlying particle physics. The resulting multiverse has a very non-trivial spacetime structure, with a multitude of eternally inflating regions connected by wormholes. If a black hole population with the predicted mass spectrum is discovered, it could be regarded as evidence for inflation and for the existence of a multiverse.

  5. Black-hole driven winds

    International Nuclear Information System (INIS)

    Punsly, B.M.

    1988-01-01

    This dissertation is a study of the physical mechanism that allows a large scale magnetic field to torque a rapidly rotating, supermassive black hole. This is an interesting problem as it has been conjectured that rapidly rotating black holes are the central engines that power the observed extragalactic double radio sources. Axisymmetric solutions of the curved space-time version of Maxwell's equations in the vacuum do not torque black holes. Plasma must be introduced for the hole to mechanically couple to the field. The dynamical aspect of rotating black holes that couples the magnetic field to the hole is the following. A rotating black hole forces the external geometry of space-time to rotate (the dragging of inertial frames). Inside of the stationary limit surface, the ergosphere, all physical particle trajectories must appear to rotate in the same direction as the black hole as viewed by the stationary observers at asymptotic infinity. In the text, it is demonstrated how plasma that is created on field lines that thread both the ergosphere and the equatorial plane will be pulled by gravity toward the equator. By the aforementioned properties of the ergosphere, the disk must rotate. Consequently, the disk acts like a unipolar generator. It drives a global current system that supports the toroidal magnetic field in an outgoing, magnetically dominated wind. This wind carries energy (mainly in the form of Poynting flux) and angular momentum towards infinity. The spin down of the black hole is the ultimate source of this energy and angular momentum flux

  6. Statistical Hair on Black Holes

    International Nuclear Information System (INIS)

    Strominger, A.

    1996-01-01

    The Bekenstein-Hawking entropy for certain BPS-saturated black holes in string theory has recently been derived by counting internal black hole microstates at weak coupling. We argue that the black hole microstate can be measured by interference experiments even in the strong coupling region where there is clearly an event horizon. Extracting information which is naively behind the event horizon is possible due to the existence of statistical quantum hair carried by the black hole. This quantum hair arises from the arbitrarily large number of discrete gauge symmetries present in string theory. copyright 1996 The American Physical Society

  7. Thermodynamics of Accelerating Black Holes.

    Science.gov (United States)

    Appels, Michael; Gregory, Ruth; Kubizňák, David

    2016-09-23

    We address a long-standing problem of describing the thermodynamics of an accelerating black hole. We derive a standard first law of black hole thermodynamics, with the usual identification of entropy proportional to the area of the event horizon-even though the event horizon contains a conical singularity. This result not only extends the applicability of black hole thermodynamics to realms previously not anticipated, it also opens a possibility for studying novel properties of an important class of exact radiative solutions of Einstein equations describing accelerated objects. We discuss the thermodynamic volume, stability, and phase structure of these black holes.

  8. Black hole thermodynamical entropy

    International Nuclear Information System (INIS)

    Tsallis, Constantino; Cirto, Leonardo J.L.

    2013-01-01

    As early as 1902, Gibbs pointed out that systems whose partition function diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs (BG) theory. Consistently, since the pioneering Bekenstein-Hawking results, physically meaningful evidence (e.g., the holographic principle) has accumulated that the BG entropy S BG of a (3+1) black hole is proportional to its area L 2 (L being a characteristic linear length), and not to its volume L 3 . Similarly it exists the area law, so named because, for a wide class of strongly quantum-entangled d-dimensional systems, S BG is proportional to lnL if d=1, and to L d-1 if d>1, instead of being proportional to L d (d ≥ 1). These results violate the extensivity of the thermodynamical entropy of a d-dimensional system. This thermodynamical inconsistency disappears if we realize that the thermodynamical entropy of such nonstandard systems is not to be identified with the BG additive entropy but with appropriately generalized nonadditive entropies. Indeed, the celebrated usefulness of the BG entropy is founded on hypothesis such as relatively weak probabilistic correlations (and their connections to ergodicity, which by no means can be assumed as a general rule of nature). Here we introduce a generalized entropy which, for the Schwarzschild black hole and the area law, can solve the thermodynamic puzzle. (orig.)

  9. Effects of pushing techniques in birth on mother and fetus: a randomized study.

    Science.gov (United States)

    Yildirim, Gulay; Beji, Nezihe Kizilkaya

    2008-03-01

    The Valsalva pushing technique is used routinely in the second stage of labor in many countries, and it is accepted as standard obstetric management in Turkey. The purpose of this study was to determine the effects of pushing techniques on mother and fetus in birth in this setting. This randomized study was conducted between July 2003 and June 2004 in Bakirkoy Maternity and Children's Teaching Hospital in Istanbul, Turkey. One hundred low-risk primiparas between 38 and 42 weeks' gestation, who expected a spontaneous vaginal delivery, were randomized to either a spontaneous pushing group or a Valsalva-type pushing group. Spontaneous pushing women were informed during the first stage of labor about spontaneous pushing technique (open glottis pushing while breathing out) and were supported in pushing spontaneously in the second stage of labor. Similarly, Valsalva pushing women were informed during the first stage of labor about the Valsalva pushing technique (closed glottis pushing while holding their breath) and were supported in using Valsalva pushing in the second stage of labor. Perineal tears, postpartum hemorrhage, and hemoglobin levels were evaluated in mothers; and umbilical artery pH, Po(2) (mmHg), and Pco(2) (mmHg) levels and Apgar scores at 1 and 5 minutes were evaluated in newborns in both groups. No significant differences were found between the two groups in their demographics, incidence of nonreassuring fetal surveillance patterns, or use of oxytocin. The second stage of labor and duration of the expulsion phase were significantly longer with Valsalva-type pushing. Differences in the incidence of episiotomy, perineal tears, or postpartum hemorrhage were not significant between the groups. The baby fared better with spontaneous pushing, with higher 1- and 5-minute Apgar scores, and higher umbilical cord pH and Po(2) levels. After the birth, women expressed greater satisfaction with spontaneous pushing. Educating women about the spontaneous pushing

  10. Stellar black holes and the origin of cosmic acceleration

    International Nuclear Information System (INIS)

    Prescod-Weinstein, Chanda; Afshordi, Niayesh; Balogh, Michael L.

    2009-01-01

    The discovery of cosmic acceleration has presented a unique challenge for cosmologists. As observational cosmology forges ahead, theorists have struggled to make sense of a standard model that requires extreme fine-tuning. This challenge is known as the cosmological constant problem. The theory of gravitational aether is an alternative to general relativity that does not suffer from this fine-tuning problem, as it decouples the quantum field theory vacuum from geometry, while remaining consistent with other tests of gravity. In this paper, we study static black hole solutions in this theory and show that it manifests a UV-IR coupling: Aether couples the space-time metric close to the black hole horizon, to metric at infinity. We then show that using the trans-Planckian ansatz (as a quantum gravity effect) close to the black hole horizon, leads to an accelerating cosmological solution, far from the horizon. Interestingly, this acceleration matches current observations for stellar-mass black holes. Based on our current understanding of the black hole accretion history in the Universe, we then make a prediction for how the effective dark energy density should evolve with redshift, which can be tested with future dark energy probes.

  11. Effect of spontaneous pushing versus Valsalva pushing in the second stage of labour on mother and fetus: a systematic review of randomised trials

    NARCIS (Netherlands)

    Prins, M. [=Marianne; Boxem, J.; Lucas, C.; Hutton, E.

    2011-01-01

    To critically evaluate any benefit or harm for the mother and her baby of Valsalva pushing versus spontaneous pushing in the second stage of labour. Electronic databases from MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials were systematically searched (last search May

  12. Pair of accelerated black holes in an anti-de Sitter background: The AdS C metric

    International Nuclear Information System (INIS)

    Dias, Oscar J.C.; Lemos, Jose P.S.

    2003-01-01

    The anti-de Sitter C metric (AdS C metric) is characterized by a quite interesting new feature when compared with the C metric in flat or de Sitter backgrounds. Indeed, contrary to what happens in these two last exact solutions, the AdS C metric only describes a pair of accelerated black holes if the acceleration parameter satisfies A>1/l, where l is the cosmological length. The two black holes cannot interact gravitationally and their acceleration is totally provided by the pressure exerted by a strut that pushes the black holes apart. Our analysis is based on the study of the causal structure, on the description of the solution in the AdS 4-hyperboloid in a 5D Minkowski spacetime, and on the physics of the strut. We also analyze the cases A=1/l and A<1/l that represent a single accelerated black hole in the AdS background

  13. Free-Electron Lasers Push Into New Frontiers

    International Nuclear Information System (INIS)

    Benson, Stephen V.

    2003-01-01

    From the early days of the development of free-electron lasers (FELs) the promise of high power and short wavelengths has tantalized physicists and other scientists. Recent developments in accelerator technologies and some new discoveries about the physics of FELs have allowed researchers to push the performance of FELs into new frontiers of high power, short wavelength, and ultra-short pulses. Spin-offs from the FELs have also opened up new radiation sources in the THz, X-ray and gamma ray wavelength ranges

  14. N -annulated perylene-based push-pull-type sensitizers

    KAUST Repository

    Qi, Qingbiao; Wang, Xingzhu; Fan, Li; Zheng, Bin; Zeng, Wangdong; Luo, Jie; Huang, Kuo-Wei; Wang, Qing; Wu, Jishan

    2015-01-01

    Alkoxy-wrapped N-annulated perylene (NP) was synthesized and used as a rigid and coplanar π-linker for three push-pull type metal-free sensitizers QB1-QB3. Their optical and electrochemical properties were tuned by varying the structure of acceptor. These new dyes were applied in Co(II)/(III) based dye-sensitized solar cells, and power conversion efficiency up to 6.95% was achieved, indicating that NP could be used as a new building block for the design of high-performance sensitizers in the future.

  15. N -annulated perylene-based push-pull-type sensitizers

    KAUST Repository

    Qi, Qingbiao

    2015-02-06

    Alkoxy-wrapped N-annulated perylene (NP) was synthesized and used as a rigid and coplanar π-linker for three push-pull type metal-free sensitizers QB1-QB3. Their optical and electrochemical properties were tuned by varying the structure of acceptor. These new dyes were applied in Co(II)/(III) based dye-sensitized solar cells, and power conversion efficiency up to 6.95% was achieved, indicating that NP could be used as a new building block for the design of high-performance sensitizers in the future.

  16. Theory-Agnostic Constraints on Black-Hole Dipole Radiation with Multiband Gravitational-Wave Astrophysics.

    Science.gov (United States)

    Barausse, Enrico; Yunes, Nicolás; Chamberlain, Katie

    2016-06-17

    The aLIGO detection of the black-hole binary GW150914 opens a new era for probing extreme gravity. Many gravity theories predict the emission of dipole gravitational radiation by binaries. This is excluded to high accuracy in binary pulsars, but entire classes of theories predict this effect predominantly (or only) in binaries involving black holes. Joint observations of GW150914-like systems by aLIGO and eLISA will improve bounds on dipole emission from black-hole binaries by 6 orders of magnitude relative to current constraints, provided that eLISA is not dramatically descoped.

  17. 30 CFR 57.7055 - Intersecting holes.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Intersecting holes. 57.7055 Section 57.7055... Jet Piercing Drilling-Surface and Underground § 57.7055 Intersecting holes. Holes shall not be drilled where there is a danger of intersecting a misfired hole or a hole containing explosives, blasting agents...

  18. 30 CFR 56.7055 - Intersecting holes.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Intersecting holes. 56.7055 Section 56.7055... Piercing Drilling § 56.7055 Intersecting holes. Holes shall not be drilled where there is a danger of intersecting a misfired hole or a hole containing explosives blasting agents, or detonators. [56 FR 46508, Sept...

  19. Probe based manipulation and assembly of nanowires into organized mesostructures

    Science.gov (United States)

    Reynolds, K.; Komulainen, J.; Kivijakola, J.; Lovera, P.; Iacopino, D.; Pudas, M.; Vähäkangas, J.; Röning, J.; Redmond, G.

    2008-12-01

    A convenient approach to patterning inorganic and organic nanowires using a novel probe manipulator is presented. The system utilizes an electrochemically etched tungsten wire probe mounted onto a 3D actuator that is directed by a 3D controller. When it is engaged by the user, the movement of the probe and the forces experienced by the tip are simultaneously reported in real time. Platinum nanowires are manipulated into organized mesostructures on silicon chip substrates. In particular, individual nanowires are systematically removed from aggregates, transferred to a chosen location, and manipulated into complex structures in which selected wires occupy specific positions with defined orientations. Rapid prototyping of complex mesostructures, by pushing, rotating and bending conjugated polymer, i.e., polyfluorene, nanowires into various configurations, is also achieved. By exploiting the strong internal axial alignment of polymer chains within the polyfluorene nanowires, mesostructures tailored to exhibit distinctly anisotropic optical properties, such as birefringence and photoluminescence dichroism, are successfully assembled on fused silica substrates.

  20. Probe based manipulation and assembly of nanowires into organized mesostructures

    International Nuclear Information System (INIS)

    Reynolds, K; Lovera, P; Iacopino, D; Redmond, G; Komulainen, J; Pudas, M; Vaehaekangas, J; Kivijakola, J; Roening, J

    2008-01-01

    A convenient approach to patterning inorganic and organic nanowires using a novel probe manipulator is presented. The system utilizes an electrochemically etched tungsten wire probe mounted onto a 3D actuator that is directed by a 3D controller. When it is engaged by the user, the movement of the probe and the forces experienced by the tip are simultaneously reported in real time. Platinum nanowires are manipulated into organized mesostructures on silicon chip substrates. In particular, individual nanowires are systematically removed from aggregates, transferred to a chosen location, and manipulated into complex structures in which selected wires occupy specific positions with defined orientations. Rapid prototyping of complex mesostructures, by pushing, rotating and bending conjugated polymer, i.e., polyfluorene, nanowires into various configurations, is also achieved. By exploiting the strong internal axial alignment of polymer chains within the polyfluorene nanowires, mesostructures tailored to exhibit distinctly anisotropic optical properties, such as birefringence and photoluminescence dichroism, are successfully assembled on fused silica substrates.

  1. Target-oriented retrieval of subsurface wave fields - Pushing the resolution limits in seismic imaging

    Science.gov (United States)

    Vasconcelos, Ivan; Ozmen, Neslihan; van der Neut, Joost; Cui, Tianci

    2017-04-01

    Travelling wide-bandwidth seismic waves have long been used as a primary tool in exploration seismology because they can probe the subsurface over large distances, while retaining relatively high spatial resolution. The well-known Born resolution limit often seems to be the lower bound on spatial imaging resolution in real life examples. In practice, data acquisition cost, time constraints and other factors can worsen the resolution achieved by wavefield imaging. Could we obtain images whose resolution beats the Born limits? Would it be practical to achieve it, and what are we missing today to achieve this? In this talk, we will cover aspects of linear and nonlinear seismic imaging to understand elements that play a role in obtaining "super-resolved" seismic images. New redatuming techniques, such as the Marchenko method, enable the retrieval of subsurface fields that include multiple scattering interactions, while requiring relatively little knowledge of model parameters. Together with new concepts in imaging, such as Target-Enclosing Extended Images, these new redatuming methods enable new targeted imaging frameworks. We will make a case as to why target-oriented approaches to reconstructing subsurface-domain wavefields from surface data may help in increasing the resolving power of seismic imaging, and in pushing the limits on parameter estimation. We will illustrate this using a field data example. Finally, we will draw connections between seismic and other imaging modalities, and discuss how this framework could be put to use in other applications

  2. Black-Hole Mass Measurements

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2004-01-01

    The applicability and apparent uncertainties of the techniques currently available for measuring or estimating black-hole masses in AGNs are briefly summarized.......The applicability and apparent uncertainties of the techniques currently available for measuring or estimating black-hole masses in AGNs are briefly summarized....

  3. ATLAS simulated black hole event

    CERN Multimedia

    Pequenão, J

    2008-01-01

    The simulated collision event shown is viewed along the beampipe. The event is one in which a microscopic-black-hole was produced in the collision of two protons (not shown). The microscopic-black-hole decayed immediately into many particles. The colors of the tracks show different types of particles emerging from the collision (at the center).

  4. Drilling miniature holes, Part III

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, L.K.

    1978-07-01

    Miniature components for precision electromechanical mechanisms such as switches, timers, and actuators typically require a number of small holes. Because of the precision required, the workpiece materials, and the geometry of the parts, most of these holes must be produced by conventional drilling techniques. The use of such techniques is tedious and often requires considerable trial and error to prevent drill breakage, minimize hole mislocation and variations in hole diameter. This study of eight commercial drill designs revealed that printed circuit board drills produced better locational and size repeatability than did other drills when centerdrilling was not used. Boring holes 1 mm in dia, or less, as a general rule did not improve hole location in brass or stainless steel. Hole locations of patterns of 0.66-mm holes can be maintained within 25.4-..mu..m diametral positional tolerance if setup misalignments can be eliminated. Size tolerances of +- 3.8 ..mu..m can be maintained under some conditions when drilling flat plates. While these levels of precision are possible with existing off-the-shelf drills, they may not be practical in many cases.

  5. Optical appearance of white holes

    International Nuclear Information System (INIS)

    Lake, K.; Roeder, R.C.

    1978-01-01

    The detailed optical properties of white holes are examined within the framework of geometrical optics. It is shown that the appearance of the objects most likely to be observed at late times is in fact determined by their early histories. These ccalculations indicate that one cannot invoke the simple concept of a stable white hole as a ''natural'' explanation of highly energetic astrophysical phenomena

  6. Probe-diverse ptychography

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, I., E-mail: isaac.russellpeterson@rmit.edu.au [ARC Centre of Excellence for Coherent X-ray Science, the University of Melbourne, School of Physics, Victoria 3010 (Australia); Harder, R. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Robinson, I.K. [Research Complex at Harwell, Didcot, Oxfordshire OX11 0DE (United Kingdom); London Centre for Nanotechnology, University College London, London WC1H 0AH (United Kingdom)

    2016-12-15

    We propose an extension of ptychography where the target sample is scanned separately through several probes with distinct amplitude and phase profiles and a diffraction image is recorded for each probe and each sample translation. The resulting probe-diverse dataset is used to iteratively retrieve high-resolution images of the sample and all probes simultaneously. The method is shown to yield significant improvement in the reconstructed sample image compared to the image obtained using the standard single-probe ptychographic phase-retrieval scheme.

  7. Bright and photostable push-pull pyrene dye visualizes lipid order variation between plasma and intracellular membranes.

    Science.gov (United States)

    Niko, Yosuke; Didier, Pascal; Mely, Yves; Konishi, Gen-ichi; Klymchenko, Andrey S

    2016-01-11

    Imaging lipid organization in cell membranes requires advanced fluorescent probes. Here, we show that a recently synthesized push-pull pyrene (PA), similarly to popular probe Laurdan, changes the emission maximum as a function of lipid order, but outperforms it by spectroscopic properties. In addition to red-shifted absorption compatible with common 405 nm diode laser, PA shows higher brightness and much higher photostability than Laurdan in apolar membrane environments. Moreover, PA is compatible with two-photon excitation at wavelengths >800 nm, which was successfully used for ratiometric imaging of coexisting liquid ordered and disordered phases in giant unilamellar vesicles. Fluorescence confocal microscopy in Hela cells revealed that PA efficiently stains the plasma membrane and the intracellular membranes at >20-fold lower concentrations, as compared to Laurdan. Finally, ratiometric imaging using PA reveals variation of lipid order within different cellular compartments: plasma membranes are close to liquid ordered phase of model membranes composed of sphingomyelin and cholesterol, while intracellular membranes are much less ordered, matching well membranes composed of unsaturated phospholipids without cholesterol. These differences in the lipid order were confirmed by fluorescence lifetime imaging (FLIM) at the blue edge of PA emission band. PA probe constitutes thus a new powerful tool for biomembrane research.

  8. Taking the Pulse of a Black Hole System

    Science.gov (United States)

    2011-01-01

    amount of energy into its surroundings," said Neilsen. "All that energy has profound consequences for the disk, even very far from the black hole." Changes in the X-ray spectrum observed by RXTE during each heartbeat reveal that the inner region of the disk, at only a few times the radius of the black hole's event horizon, emits enough radiation to push material away from the black hole. Eventually the disk gets so bright and so hot that it essentially disintegrates and plunges towards the black hole. Then the cycle begins again. "This behavior is a clear and startling demonstration of the power of radiation in the fight against gravity," said co-author Ron Remillard of the Massachusetts Institute of Technology. "During the heartbeat state, radiation prevents the black hole from ingesting as much material as it would otherwise." Neilsen and his colleagues estimated that the rate at which material falls onto the black hole changes by about a factor of ten during each cycle, with the maximum rate coinciding with the X-ray pulse. Between pulses, the inner part of the disk refills from material farther away from the black hole. The astronomers also used Chandra's high-resolution spectrograph to study the effects of this heartbeat variation on regions of the disk very far from the black hole, at distances of about 100,000 to a million times the radius of the event horizon. By analyzing the Chandra spectrum, they found a very strong wind being driven away from the outer parts of the disk. The wind changed significantly in just 5 seconds, nearly 100 times faster than has ever been seen in a wind from a stellar-mass black hole. The researchers concluded that the strong X-ray pulse from the inner disk must heat the outer disk. This heating process launches a wind, so that each new pulse drives more wind from the disk. The rate of mass expelled in this wind is remarkably high, as much as 25 times the maximum rate at which matter falls onto the black hole. "All that energy blows

  9. Control of vertical posture while standing on a sliding board and pushing an object.

    Science.gov (United States)

    Lee, Yun-Ju; Chen, Bing; Liang, Jing-Nong; Aruin, Alexander S

    2018-03-01

    Voluntary pushing or translation perturbation of the support surface each induces a body perturbation that affects postural control. The objective of the study was to investigate anticipatory (APA) and compensatory (CPA) postural adjustments when pushing an object (that induces self-initiated perturbation) and standing on a sliding board (that induces translational perturbation). Thirteen healthy young participants were instructed to push a handle with both hands while standing on a sliding board that was either free to move in the anterior-posterior direction or stationary. Electromyographic activity (EMG) of trunk and lower extremity muscles, center of pressure (COP) displacements, and the forces exerted by the hand were recorded and analyzed during the APA and CPA phases. When the sliding board was free to move during pushing (translation perturbation), onsets of activity of ventral leg muscles and COP displacement were delayed as compared to pushing when standing on a stationary board. Moreover, magnitudes of shank muscle activity and the COP displacement were decreased. When pushing heavier weight, magnitudes of muscle activity, COP displacement, and pushing force increased. The magnitude of activity of the shank muscles during the APA and CPA phases in conditions with translational perturbation varied with the magnitude of the pushing weight. The outcome of the study suggests that the central nervous system prioritizes the pushing task while attenuates the source of additional perturbation induced by translation perturbation. These results could be used in the development of balance re-training paradigms involving pushing weight while standing on a sliding surface.

  10. Medical and Non-Medical Factors Influencing Utilization of Delayed Pushing in the Second Stage

    Science.gov (United States)

    FREY, Heather A.; TUULI, Methodius G.; CORTEZ, Sarah; ODIBO, Anthony O.; ROEHL, Kimberly A.; SHANKS, Anthony L.; MACONES, George A.; CAHILL, Alison G.

    2014-01-01

    Objective To evaluate factors impacting selection to delayed pushing in the second stage of labor. Study design This case-control study was a secondary analysis of a large retrospective cohort study. Cases included women who delayed pushing for 60 minutes or more in the second stage of labor. Controls began pushing prior to 60 minutes from the time of diagnosis of complete dilation. Demographic, labor, and nonmedical factors were compared among cases and controls. Logistic regression modelling was used to identify factors independently associated with delayed pushing. Results We identified 471 women who delayed pushing and 4,819 controls. Nulliparity, maternal body mass index > 25, high fetal station at complete dilation, regional anesthesia use, and start of second stage during staffing shift change were independent factors associated with increased use of delayed pushing. On the other hand, black race and second stage management during night shift were associated with lower odds of employing delayed pushing. Delayed pushing was more commonly employed in nulliparous women, but 38.9% of multiparous women also delayed pushing. Conclusion We identified multiple factors associated with use of delayed pushing. This study helps to define current patterns of second stage labor management. PMID:23208765

  11. Medical and nonmedical factors influencing utilization of delayed pushing in the second stage.

    Science.gov (United States)

    Frey, Heather A; Tuuli, Methodius G; Cortez, Sarah; Odibo, Anthony O; Roehl, Kimberly A; Shanks, Anthony L; Macones, George A; Cahill, Alison G

    2013-08-01

    To evaluate factors impacting selection to delayed pushing in the second stage of labor. This case-control study was a secondary analysis of a large retrospective cohort study. Cases included women who delayed pushing for 60 minutes or more in the second stage of labor. Controls began pushing prior to 60 minutes from the time of diagnosis of complete dilation. Demographic, labor, and nonmedical factors were compared among cases and controls. Logistic regression modeling was used to identify factors independently associated with delayed pushing. We identified 471 women who delayed pushing and 4819 controls. Nulliparity, maternal body mass index > 25, high fetal station at complete dilation, regional anesthesia use, and start of second stage during staffing shift change were independent factors associated with increased use of delayed pushing. On the other hand, black race and second-stage management during night shift were associated with lower odds of employing delayed pushing. Delayed pushing was more commonly employed in nulliparous women, but 38.9% of multiparous women also delayed pushing. We identified multiple factors associated with use of delayed pushing. This study helps to define current patterns of second-stage labor management. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  12. Traversing probe system

    International Nuclear Information System (INIS)

    Mashburn, D.N.; Stevens, R.H.; Woodall, H.C.

    1977-01-01

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride. 10 claims, 6 figures

  13. Traversing probe system

    Science.gov (United States)

    Mashburn, Douglas N.; Stevens, Richard H.; Woodall, Harold C.

    1977-01-01

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride.

  14. Black holes and everyday physics

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1982-01-01

    Black holes have piqued much curiosity. But thus far they have been important only in ''remote'' subjects like astrophysics and quantum gravity. It is shown that the situation can be improved. By a judicious application of black hole physics, one can obtain new results in ''everyday physics''. For example, black holes yield a quantum universal upper bound on the entropy-to-energy ratio for ordinary thermodynamical systems which was unknown earlier. It can be checked, albeit with much labor, by ordinary statistical methods. Black holes set a limitation on the number of species of elementary particles-quarks, leptons, neutrinos - which may exist. And black holes lead to a fundamental limitation on the rate at which information can be transferred for given message energy by any communication system. (author)

  15. The search for black holes

    International Nuclear Information System (INIS)

    Torn, K.

    1976-01-01

    Conceivable experimental investigations to prove the existence of black holes are discussed. Double system with a black hole turning around a star-satellite are in the spotlight. X-radiation emmited by such systems and resulting from accretion of the stellar gas by a black hole, and the gas heating when falling on the black hole might prove the model suggested. A source of strong X-radiation observed in the Cygnus star cluster and referred to as Cygnus X-1 may be thus identified as a black hole. Direct registration of short X-ray pulses with msec intervals might prove the suggestion. The lack of appropriate astrophysic facilities is pointed out to be the major difficulty on the way of experimental verifications

  16. Black hole final state conspiracies

    International Nuclear Information System (INIS)

    McInnes, Brett

    2009-01-01

    The principle that unitarity must be preserved in all processes, no matter how exotic, has led to deep insights into boundary conditions in cosmology and black hole theory. In the case of black hole evaporation, Horowitz and Maldacena were led to propose that unitarity preservation can be understood in terms of a restriction imposed on the wave function at the singularity. Gottesman and Preskill showed that this natural idea only works if one postulates the presence of 'conspiracies' between systems just inside the event horizon and states at much later times, near the singularity. We argue that some AdS black holes have unusual internal thermodynamics, and that this may permit the required 'conspiracies' if real black holes are described by some kind of sum over all AdS black holes having the same entropy

  17. String-Corrected Black Holes

    Energy Technology Data Exchange (ETDEWEB)

    Hubeny, V.

    2005-01-12

    We investigate the geometry of four dimensional black hole solutions in the presence of stringy higher curvature corrections to the low energy effective action. For certain supersymmetric two charge black holes these corrections drastically alter the causal structure of the solution, converting seemingly pathological null singularities into timelike singularities hidden behind a finite area horizon. We establish, analytically and numerically, that the string-corrected two-charge black hole metric has the same Penrose diagram as the extremal four-charge black hole. The higher derivative terms lead to another dramatic effect--the gravitational force exerted by a black hole on an inertial observer is no longer purely attractive. The magnitude of this effect is related to the size of the compactification manifold.

  18. Compressibility of rotating black holes

    International Nuclear Information System (INIS)

    Dolan, Brian P.

    2011-01-01

    Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of nonpositive cosmological constant. The adiabatic compressibility vanishes for a nonrotating black hole and is maximal in the extremal case--comparable with, but still less than, that of a cold neutron star. A speed of sound v s is associated with the adiabatic compressibility, which is equal to c for a nonrotating black hole and decreases as the angular momentum is increased. An extremal black hole has v s 2 =0.9 c 2 when the cosmological constant vanishes, and more generally v s is bounded below by c/√(2).

  19. Electrical resistivity probes

    Science.gov (United States)

    Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.

    2003-10-21

    A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

  20. Simulation of push-pull inverter using wide bandgap devices

    Science.gov (United States)

    Al-badri, Mustafa; Matin, Mohammed A.

    2016-09-01

    This paper discusses the use of wide bandgap devices (SiC-MOSFET) in the design of a push-pull inverter which provides inexpensive low power dc-ac inverters. The parameters used were 1200V SiC MOSFET(C2M0040120D) made by power company ROHM. This modeling was created using parameters that were provided from a device datasheet. The spice model is provided by this company to study the effect of adding this component on push-pull inverter ordinary circuit and compared results between SiC MOSFET and silicon MOSFET (IRFP260M). The results focused on Vout and Vmos stability as well as on output power and MOSFET power loss because it is a very crucial aspect on DC-AC inverter design. These results are done using the National Instrument simulation program (Multisim 14). It was found that power loss is better in the 12 and 15 vdc inverter. The Vout in the SIC MOSFET circuit shows more stability in the high current low resistance load in comparison to the Silicon MOSFET circuit and this will improve the overall performance of the circuit.

  1. Reduction of discomfort in pushing an industrial trolley using ergonomics

    Science.gov (United States)

    Kumar, M. Wilson; Vijay, S. J.; Vasudev, K. L.; Darius Gnanaraj, S.

    2017-11-01

    Poor design of industrial trolleys lead to more compressive stress on the low back of industrial workers. The research work reported in this paper recommends a handle height of an industrial trolley for use by the local population, which reduces the compressive stress on the low back. Experiments were conducted in a laboratory on five subjects of varying stature 165, 173, 174, 175 and 182 cm, with five different handle heights 90, 95, 100, 105 and 110 cm. A four wheeled trolley has been used to conduct the experiments. Caster wheels diameters of 100, 125 and 150 mm made of polyurethane were used. It is found that a handle height of 110 cm allows the users to exert minimum force during the initial pushing. A biomechanical model was employed to calculate the compressive force experienced by L5/S1 disc and it is found that the compressive load will be the least when the handle height is 110 cm. Optimization of handle height using Genetic Algorithm approach, Heart rate analysis and EMG analysis confirm that a handle height of 110 cm and a wheel diameter of 150 mm will reduce the discomfort of industry workers pushing trolleys.

  2. Explanatory Definitions of the Technology Push Success Factors

    Directory of Open Access Journals (Sweden)

    Jari Matti Sarja

    2015-04-01

    Full Text Available The main task for most development-intensive organizations is to create, develop and commercialize new products and services. Because development processes are risky and failure rates are high, especially in the case of technology pushed projects, unambiguous success factors are valuable knowledge for the management of development-intensive firms. New product development and innovation literature has presented many success factors for developed products, but, unfortunately, many of them are nebulous in nature. The aim of this paper is to clarify what elements comprise the exact factors. After an extensive review and screening of the technology push success factor related literature, a total of 13 success factors were rationalized and transcribed according the previous literature. As a result, three separate keynotes were recognized, and the survey instrument framework was proposed. The practical relevance of this study is to help firm management to recognize the real actions needed to reduce product development risks and also to help scholars to focus on key issues when studying the key factors of breakthrough development cases.

  3. Black Hole Coalescence: The Gravitational Wave Driven Phase

    Science.gov (United States)

    Schnittman, Jeremy D.

    2011-01-01

    When two supermassive black holes (SMBHS) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.

  4. An intermediate-mass black hole in the centre of the globular cluster 47 Tucanae.

    Science.gov (United States)

    Kızıltan, Bülent; Baumgardt, Holger; Loeb, Abraham

    2017-02-08

    Intermediate-mass black holes should help us to understand the evolutionary connection between stellar-mass and super-massive black holes. However, the existence of intermediate-mass black holes is still uncertain, and their formation process is therefore unknown. It has long been suspected that black holes with masses 100 to 10,000 times that of the Sun should form and reside in dense stellar systems. Therefore, dedicated observational campaigns have targeted globular clusters for many decades, searching for signatures of these elusive objects. All candidate signatures appear radio-dim and do not have the X-ray to radio flux ratios required for accreting black holes. Based on the lack of an electromagnetic counterpart, upper limits of 2,060 and 470 solar masses have been placed on the mass of a putative black hole in 47 Tucanae (NGC 104) from radio and X-ray observations, respectively. Here we show there is evidence for a central black hole in 47 Tucanae with a mass of solar masses when the dynamical state of the globular cluster is probed with pulsars. The existence of an intermediate-mass black hole in the centre of one of the densest clusters with no detectable electromagnetic counterpart suggests that the black hole is not accreting at a sufficient rate to make it electromagnetically bright and therefore, contrary to expectations, is gas-starved. This intermediate-mass black hole might be a member of an electromagnetically invisible population of black holes that grow into supermassive black holes in galaxies.

  5. Caged black holes: Black holes in compactified spacetimes. I. Theory

    International Nuclear Information System (INIS)

    Kol, Barak; Sorkin, Evgeny; Piran, Tsvi

    2004-01-01

    In backgrounds with compact dimensions there may exist several phases of black objects including a black hole and a black string. The phase transition between them raises questions and touches on fundamental issues such as topology change, uniqueness, and cosmic censorship. No analytic solution is known for the black hole, and moreover one can expect approximate solutions only for very small black holes, while phase transition physics happens when the black hole is large. Hence we turn to numerical solutions. Here some theoretical background to the numerical analysis is given, while the results will appear in a subsequent paper. The goals for a numerical analysis are set. The scalar charge and tension along the compact dimension are defined and used as improved order parameters which put both the black hole and the black string at finite values on the phase diagram. The predictions for small black holes are presented. The differential and the integrated forms of the first law are derived, and the latter (Smarr's formula) can be used to estimate the 'overall numerical error'. Field asymptotics and expressions for physical quantities in terms of the numerical values are supplied. The techniques include the 'method of equivalent charges', free energy, dimensional reduction, and analytic perturbation for small black holes

  6. When Supermassive Black Holes Wander

    Science.gov (United States)

    Kohler, Susanna

    2018-05-01

    Are supermassive black holes found only at the centers of galaxies? Definitely not, according to a new study in fact, galaxies like the Milky Way may harbor several such monsters wandering through their midst.Collecting Black Holes Through MergersIts generally believed that galaxies are built up hierarchically, growing in size through repeated mergers over time. Each galaxy in a major merger likely hosts a supermassive black hole a black hole of millions to billions of times the mass of the Sun at its center. When a pair of galaxies merges, their supermassive black holes will often sink to the center of the merger via a process known as dynamical friction. There the supermassive black holes themselves will eventually merge in a burst of gravitational waves.Spatial distribution and velocities of wandering supermassive black holes in three of the authors simulated galaxies, shown in edge-on (left) and face-on (right) views of the galaxy disks. Click for a closer look. [Tremmel et al. 2018]But if a galaxy the size of the Milky Way was built through a history of many major galactic mergers, are we sure that all its accumulated supermassive black holes eventually merged at the galactic center? A new study suggests that some of these giants might have escaped such a fate and they now wander unseen on wide orbits through their galaxies.Black Holes in an Evolving UniverseLed by Michael Tremmel (Yale Center for Astronomy Astrophysics), a team of scientists has used data from a large-scale cosmological simulation, Romulus25, to explore the possibility of wandering supermassive black holes. The Romulus simulations are uniquely suited to track the formation and subsequent orbital motion of supermassive black holes as galactic halos are built up through mergers over the history of the universe.From these simulations, Tremmel and collaborators find an end total of 316 supermassive black holes residing within the bounds of 26 Milky-Way-mass halos. Of these, roughly a third are

  7. Black holes and quantum processes in them

    International Nuclear Information System (INIS)

    Frolov, V.P.

    1976-01-01

    The latest achievements in the physics of black holes are reviewed. The problem of quantum production in a strong gravitational field of black holes is considered. Another parallel discovered during investigation of interactions between black holes and between black holes and surrounding media, is also drawn with thermodynamics. A gravitational field of rotating black holes is considered. Some cosmological aspects of evaporation of small black holes are discussed as well as possibilities to observe them

  8. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  9. Push Recovery for Humanoid Robot in Dynamic Environment and Classifying the Data Using K-Mean

    Directory of Open Access Journals (Sweden)

    Anubha Parashar

    2016-12-01

    Full Text Available Push recovery is prime ability that is essential to be incorporated in the process of developing a robust humanoid robot to support bipedalism. In real environment it is very essential for humanoid robot to maintain balance. In this paper we are generating a control system and push recovery controller for humanoid robot walking. We apply different kind of pushes to humanoid robot and the algorithm that can bring a change in the walking stage to sustain walking. The simulation is done in 3D environment using Webots. This paper describes techniques for feature selection to foreshow push recovery for hip, ankle and knee joint. We train the system by K-Mean algorithm and testing is done on crouch data and tested results are reported. Random push data of humanoid robot is collected and classified to see whether push lie in safer region and then tested on given proposed system.

  10. A nonsingular rotating black hole

    International Nuclear Information System (INIS)

    Ghosh, Sushant G.

    2015-01-01

    The spacetime singularities in classical general relativity are inevitable, as predicated by the celebrated singularity theorems. However, it is a general belief that singularities do not exist in Nature and that they are the limitations of the general relativity. In the absence of a welldefined quantum gravity, models of regular black holes have been studied. We employ a probability distribution inspired mass function m(r) to replace the Kerr black hole mass M to represent a nonsingular rotating black hole that is identified asymptotically (r >> k, k > 0 constant) exactly as the Kerr-Newman black hole, and as the Kerr black hole when k = 0. The radiating counterpart renders a nonsingular generalization of Carmeli's spacetime as well as Vaidya's spacetime, in the appropriate limits. The exponential correction factor changing the geometry of the classical black hole to remove the curvature singularity can also be motivated by quantum arguments. The regular rotating spacetime can also be understood as a black hole of general relativity coupled to nonlinear electrodynamics. (orig.)

  11. Black holes: the membrane paradigm

    International Nuclear Information System (INIS)

    Thorne, K.S.; Price, R.H.; Macdonald, D.A.

    1986-01-01

    The physics of black holes is explored in terms of a membrane paradigm which treats the event horizon as a two-dimensional membrane embedded in three-dimensional space. A 3+1 formalism is used to split Schwarzschild space-time and the laws of physics outside a nonrotating hole, which permits treatment of the atmosphere in terms of the physical properties of thin slices. The model is applied to perturbed slowly or rapidly rotating and nonrotating holes, and to quantify the electric and magnetic fields and eddy currents passing through a membrane surface which represents a stretched horizon. Features of tidal gravitational fields in the vicinity of the horizon, quasars and active galalctic nuclei, the alignment of jets perpendicular to accretion disks, and the effects of black holes at the center of ellipsoidal star clusters are investigated. Attention is also given to a black hole in a binary system and the interactions of black holes with matter that is either near or very far from the event horizon. Finally, a statistical mechanics treatment is used to derive a second law of thermodynamics for a perfectly thermal atmosphere of a black hole

  12. Black Hole Grabs Starry Snack

    Science.gov (United States)

    2006-01-01

    [figure removed for brevity, see original site] Poster Version This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a 'ringside' seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end. The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light. The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.

  13. Black holes at neutrino telescopes

    International Nuclear Information System (INIS)

    Kowalski, M.; Ringwald, A.; Tu, H.

    2002-01-01

    In scenarios with extra dimensions and TeV-scale quantum gravity, black holes are expected to be produced in the collision of light particles at center-of-mass energies above the fundamental Planck scale with small impact parameters. Black hole production and evaporation may thus be studied in detail at the large hadron collider (LHC). But even before the LHC starts operating, neutrino telescopes such as AMANDA/IceCube, ANTARES, Baikal, and RICE have an opportunity to search for black hole signatures. Black hole production in the scattering of ultrahigh energy cosmic neutrinos on nucleons in the ice or water may initiate cascades and through-going muons with distinct characteristics above the Standard Model rate. In this Letter, we investigate the sensitivity of neutrino telescopes to black hole production and compare it to the one expected at the Pierre Auger Observatory, an air shower array currently under construction, and at the LHC. We find that, already with the currently available data, AMANDA and RICE should be able to place sensible constraints in black hole production parameter space, which are competitive with the present ones from the air shower facilities Fly's Eye and AGASA. In the optimistic case that a ultrahigh energy cosmic neutrino flux significantly higher than the one expected from cosmic ray interactions with the cosmic microwave background radiation is realized in nature, one even has discovery potential for black holes at neutrino telescopes beyond the reach of LHC. (orig.)

  14. Thermodynamic theory of black holes

    Energy Technology Data Exchange (ETDEWEB)

    Davies, P C.W. [King' s Coll., London (UK). Dept. of Mathematics

    1977-04-21

    The thermodynamic theory underlying black hole processes is developed in detail and applied to model systems. It is found that Kerr-Newman black holes undergo a phase transition at a = 0.68M or Q = 0.86M, where the heat capacity has an infinite discontinuity. Above the transition values the specific heat is positive, permitting isothermal equilibrium with a surrounding heat bath. Simple processes and stability criteria for various black hole situations are investigated. The limits for entropically favoured black hole formation are found. The Nernst conditions for the third law of thermodynamics are not satisfied fully for black holes. There is no obvious thermodynamic reason why a black hole may not be cooled down below absolute zero and converted into a naked singularity. Quantum energy-momentum tensor calculations for uncharged black holes are extended to the Reissner-Nordstrom case, and found to be fully consistent with the thermodynamic picture for Q < M. For Q < M the model predicts that 'naked' collapse also produces radiation, with such intensity that the collapsing matter is entirely evaporated away before a naked singularity can form.

  15. Characterization of nitride hole lateral transport in a charge trap flash memory by using a random telegraph signal method

    Science.gov (United States)

    Liu, Yu-Heng; Jiang, Cheng-Min; Lin, Hsiao-Yi; Wang, Tahui; Tsai, Wen-Jer; Lu, Tao-Cheng; Chen, Kuang-Chao; Lu, Chih-Yuan

    2017-07-01

    We use a random telegraph signal method to investigate nitride trapped hole lateral transport in a charge trap flash memory. The concept of this method is to utilize an interface oxide trap and its associated random telegraph signal as an internal probe to detect a local channel potential change resulting from nitride charge lateral movement. We apply different voltages to the drain of a memory cell and vary a bake temperature in retention to study the electric field and temperature dependence of hole lateral movement in a nitride. Thermal energy absorption by trapped holes in lateral transport is characterized. Mechanisms of hole lateral transport in retention are investigated. From the measured and modeled results, we find that thermally assisted trap-to-band tunneling is a major trapped hole emission mechanism in nitride hole lateral transport.

  16. Probing and Tapping: Are We Inserting Pedicle Screws Correctly?

    Science.gov (United States)

    Prasad, Vishal; Mesfin, Addisu; Lee, Robert; Reigrut, Julie; Schmidt, John

    2016-11-01

    Although there are a significant number of research publications on the topic of bone morphology and the strength of bone, the clinical significance of a failed pedicle screw is often revision surgery and the potential for further postoperative complications; especially in elderly patients with osteoporotic bone. The purpose of this report is to quantify the mechanical strength of the foam-screw interface by assessing probe/pilot hole diameter and tap sizes using statistically relevant sample sizes under highly controlled test conditions. The study consisted of two experiments and used up to three different densities of reference-grade polyurethane foam (ASTM 1839), including 0.16, 0.24, and 0.32 g/cm 3 . All screws and rods were provided by K2M Inc. and screws were inserted to a depth of 25 mm. A series of pilot holes, 1.5, 2.2, 2.7, 3.2, 3.7, 4.2, 5.0, and 6.0 mm in diameter were drilled through the entire depth of the material. A 6.5 × 45-mm pedicle screw was inserted and axially pulled from the material (n = 720). A 3.0-mm pilot hole was drilled and tapped with: no tap, 3.5-, 4.5-, 5.5-, and 6.5-mm taps. A 6.5 × 45-mm pedicle screw was inserted and axially pulled from the material (n = 300). The size of the probe/pilot hole had a nonlinear, parabolic effect on pullout strength. This shape suggests an optimum-sized probe hole for a given size pedicle screw. Too large or too small of a probe hole causes a rapid falloff in pullout strength. The tap data demonstrated that not tapping and undertapping by two or three sizes did not significantly alter the pullout strength of the screws. The data showed an exponential falloff of pullout strength when as tap size increased to the diameter of the screw. In the current study, the data show that an ideal pilot hole size half the diameter of the screw is a starting point. Also, that if tapping was necessary, to use a tap two sizes smaller than the screw being implanted. A similar optimum pilot hole or tap size may be

  17. Unveiling the edge of time black holes, white holes, wormholes

    CERN Document Server

    Gribbin, John

    1992-01-01

    Acclaimed science writer John Gribbin recounts dramatic stories that have led scientists to believe black holes and their more mysterious kin are not only real, but might actually provide a passage to other universes and travel through time.

  18. Black holes and Higgs stability

    CERN Document Server

    Tetradis, Nikolaos

    2016-09-20

    We study the effect of primordial black holes on the classical rate of nucleation of AdS regions within the standard electroweak vacuum. We find that the energy barrier for transitions to the new vacuum, which characterizes the exponential suppression of the nucleation rate, can be reduced significantly in the black-hole background. A precise analysis is required in order to determine whether the the existence of primordial black holes is compatible with the form of the Higgs potential at high temperature or density in the Standard Model or its extensions.

  19. Vacuum metastability with black holes

    Energy Technology Data Exchange (ETDEWEB)

    Burda, Philipp [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Gregory, Ruth [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Perimeter Institute, 31 Caroline Street North,Waterloo, ON, N2L 2Y5 (Canada); Moss, Ian G. annd [School of Mathematics and Statistics, Newcastle University,Newcastle Upon Tyne, NE1 7RU (United Kingdom)

    2015-08-24

    We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.

  20. Orbital resonances around black holes.

    Science.gov (United States)

    Brink, Jeandrew; Geyer, Marisa; Hinderer, Tanja

    2015-02-27

    We compute the length and time scales associated with resonant orbits around Kerr black holes for all orbital and spin parameters. Resonance-induced effects are potentially observable when the Event Horizon Telescope resolves the inner structure of Sgr A*, when space-based gravitational wave detectors record phase shifts in the waveform during the resonant passage of a compact object spiraling into the black hole, or in the frequencies of quasiperiodic oscillations for accreting black holes. The onset of geodesic chaos for non-Kerr spacetimes should occur at the resonance locations quantified here.

  1. Vacuum metastability with black holes

    International Nuclear Information System (INIS)

    Burda, Philipp; Gregory, Ruth; Moss, Ian G. annd

    2015-01-01

    We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.

  2. Tunnelling from Goedel black holes

    International Nuclear Information System (INIS)

    Kerner, Ryan; Mann, R. B.

    2007-01-01

    We consider the spacetime structure of Kerr-Goedel black holes, analyzing their parameter space in detail. We apply the tunnelling method to compute their temperature and compare the results to previous calculations obtained via other methods. We claim that it is not possible to have the closed timelike curve (CTC) horizon in between the two black hole horizons and include a discussion of issues that occur when the radius of the CTC horizon is smaller than the radius of both black hole horizons

  3. Quantum mechanics of black holes.

    Science.gov (United States)

    Witten, Edward

    2012-08-03

    The popular conception of black holes reflects the behavior of the massive black holes found by astronomers and described by classical general relativity. These objects swallow up whatever comes near and emit nothing. Physicists who have tried to understand the behavior of black holes from a quantum mechanical point of view, however, have arrived at quite a different picture. The difference is analogous to the difference between thermodynamics and statistical mechanics. The thermodynamic description is a good approximation for a macroscopic system, but statistical mechanics describes what one will see if one looks more closely.

  4. Gravitational polarizability of black holes

    International Nuclear Information System (INIS)

    Damour, Thibault; Lecian, Orchidea Maria

    2009-01-01

    The gravitational polarizability properties of black holes are compared and contrasted with their electromagnetic polarizability properties. The 'shape' or 'height' multipolar Love numbers h l of a black hole are defined and computed. They are then compared to their electromagnetic analogs h l EM . The Love numbers h l give the height of the lth multipolar 'tidal bulge' raised on the horizon of a black hole by faraway masses. We also discuss the shape of the tidal bulge raised by a test-mass m, in the limit where m gets very close to the horizon.

  5. Pushing nanoparticles of La0.7Sr0.3MnO3

    International Nuclear Information System (INIS)

    Ma, Y.-R.; Liou Yung; Yao, Y.-D.

    2004-01-01

    Pushing nanoparticles of La 0.7 Sr 0.3 MnO 3 (LSMO) on a native SiO 2 surface using atomic force microscopy (AFM) in the tapping mode is presented. The pushing is accompanied by a repulsive tip-sample interaction between the AFM tip and the LSMO nanoparticles and the physisorption of the LSMO on the SiO 2 surface. The AFM images show scratch artifacts on the surface, indicating that artificial scratches are strongly related to the pushing of the LSMO nanoparticles. A possible approach to pushing nanoparticles is proposed

  6. Range of Motion of the Ankle According to Pushing Force, Gender and Knee Position.

    Science.gov (United States)

    Cho, Kang Hee; Jeon, Yumi; Lee, Hyunkeun

    2016-04-01

    To investigate the difference of range of motion (ROM) of ankle according to pushing force, gender and knee position. One hundred and twenty-eight healthy adults (55 men, 73 women) between the ages of 20 and 51, were included in the study. One examiner measured the passive range of motion (PROM) of ankle by Dualer IQ Inclinometers and Commander Muscle Testing. ROM of ankle dorsiflexion (DF) and plantarflexion (PF) according to change of pushing force and knee position were measured at prone position. There was significant correlation between ROM and pushing force, the more pushing force leads the more ROM at ankle DF and ankle PF. Knee flexion of 90° position showed low PF angle and high ankle DF angle, as compared to the at neutral position of knee joint. ROM of ankle DF for female was greater than for male, with no significant difference. ROM of ankle PF for female was greater than male regardless of the pushing force. To our knowledge, this is the first study to assess the relationship between pushing force and ROM of ankle joint. There was significant correlation between ROM of ankle and pushing force. ROM of ankle PF for female estimated greater than male regardless of the pushing force and the number of measurement. The ROM of the ankle is measured differently according to the knee joint position. Pushing force, gender and knee joint position are required to be considered when measuring the ROM of ankle joint.

  7. Variations of the ionization push frequency in the ASK-1 chamber

    International Nuclear Information System (INIS)

    Krivoshapkin, P.A.; Mamrukova, V.P.; Skripin, G.V.; Shafer, G.V.

    1997-01-01

    The data on frequency push in the ASK-1 chamber at the Yakutsk station for 1954-1994 are analyzed. The observed eleven-year and half-year push variations are related to the solar activity. The narrowly directed galactic anisotropy with 6-8 h direction, coinciding with the direction of the helio-magnetosphere tail, formed by the solar system motion relative to stars is identified in a daily motion by sidereal time. The great barometric and temperature coefficients of the frequency pushes are obtained. This indicates the prevailing role of the nuclear-active particles in formation of pushes

  8. Upper Extremity Muscle Activity During In-Phase and Anti-Phase Continuous Pushing Tasks.

    Science.gov (United States)

    Gruevski, Kristina M; Hodder, Joanne N; Keir, Peter J

    2017-11-01

    To determine the effect of anti-phase, in-phase bimanual and unimanual simulated industrial pushing tasks and frequency on upper extremity muscle activity. Research investigating symmetrical (in-phase) and asymmetrical (anti-phase) pushing exertions is limited despite a high prevalence in industry. Fifteen female participants completed five pushing tasks using a dual handle apparatus at three frequencies: 15 cycles per minute (cpm), 30 cpm, and self-selected. Tasks included two bimanual symmetrical pushes (constrained and unconstrained), two bimanual asymmetrical pushes (reciprocating and continuous), and one right unimanual push. Surface electromyography (EMG) from the right anterior, middle, and posterior deltoid (AD, MD, and PD); right and left trapezius (RT and LT); right pectoralis major (PM); and right and left external obliques (REO and LEO) was collected and normalized to maximum voluntary effort. There was a task by frequency interaction in the AD, MD, PD, and RT ( p pushes and constrained, in-phase pushes had the highest muscle activity demands and the least amount of variability in muscle activity and therefore may present the greatest risk of injury. Anti-phase pushing is known to have a greater cognitive demand, and this study demonstrated that it also has a greater physical demand when performed continuously.

  9. Wheelchair pushing and turning: lumbar spine and shoulder loads and recommended limits.

    Science.gov (United States)

    Weston, Eric B; Khan, Safdar N; Marras, William S

    2017-12-01

    The objective of this study was to determine how simulated manual wheelchair pushing influences biomechanical loading to the lumbar spine and shoulders. Sixty-two subjects performed simulated wheelchair pushing and turning in a laboratory. An electromyography-assisted biomechanical model was used to estimate spinal loads. Moments at the shoulder joint, external hand forces and net turning torque were also assessed. Multiple linear regression techniques were employed to develop biomechanically based wheelchair pushing guidelines relating resultant hand force or net torque to spinal load. Male subjects experienced significantly greater spinal loading (p pushing (p pushing and turning can pose biomechanical risk to the lumbar spine and shoulders. Psychophysically determined maximum acceptable push forces do not appear to be protective enough of this biomechanical risk. Practitioner Summary: This laboratory study investigated biomechanical risk to the low back and shoulders during simulated wheelchair pushing. Manual wheelchair pushing posed biomechanical risk to the lumbar spine (in compression and A/P shear) and to the shoulders. Biomechanically determined wheelchair pushing thresholds are presented and are more protective than the closest psychophysically determined equivalents.

  10. Global Models of Ridge-Push Force, Geoid, and Lithospheric Strength of Oceanic plates

    Science.gov (United States)

    Mahatsente, Rezene

    2017-12-01

    An understanding of the transmission of ridge-push related stresses in the interior of oceanic plates is important because ridge-push force is one of the principal forces driving plate motion. Here, I assess the transmission of ridge-push related stresses in oceanic plates by comparing the magnitude of the ridge-push force to the integrated strength of oceanic plates. The strength is determined based on plate cooling and rheological models. The strength analysis includes low-temperature plasticity (LTP) in the upper mantle and assumes a range of possible tectonic conditions and rheology in the plates. The ridge-push force has been derived from the thermal state of oceanic lithosphere, seafloor depth and crustal age data. The results of modeling show that the transmission of ridge-push related stresses in oceanic plates mainly depends on rheology and predominant tectonic conditions. If a lithosphere has dry rheology, the estimated strength is higher than the ridge-push force at all ages for compressional tectonics and at old ages (>75 Ma) for extension. Therefore, under such conditions, oceanic plates may not respond to ridge-push force by intraplate deformation. Instead, the plates may transmit the ridge-push related stress in their interior. For a wet rheology, however, the strength of young lithosphere (stress may dissipate in the interior of oceanic plates and diffuses by intraplate deformation. The state of stress within a plate depends on the balance of far-field and intraplate forces.

  11. Black hole meiosis

    Science.gov (United States)

    van Herck, Walter; Wyder, Thomas

    2010-04-01

    The enumeration of BPS bound states in string theory needs refinement. Studying partition functions of particles made from D-branes wrapped on algebraic Calabi-Yau 3-folds, and classifying states using split attractor flow trees, we extend the method for computing a refined BPS index, [1]. For certain D-particles, a finite number of microstates, namely polar states, exclusively realized as bound states, determine an entire partition function (elliptic genus). This underlines their crucial importance: one might call them the ‘chromosomes’ of a D-particle or a black hole. As polar states also can be affected by our refinement, previous predictions on elliptic genera are modified. This can be metaphorically interpreted as ‘crossing-over in the meiosis of a D-particle’. Our results improve on [2], provide non-trivial evidence for a strong split attractor flow tree conjecture, and thus suggest that we indeed exhaust the BPS spectrum. In the D-brane description of a bound state, the necessity for refinement results from the fact that tachyonic strings split up constituent states into ‘generic’ and ‘special’ states. These are enumerated separately by topological invariants, which turn out to be partitions of Donaldson-Thomas invariants. As modular predictions provide a check on many of our results, we have compelling evidence that our computations are correct.

  12. Sleeve Push Technique: A Novel Method of Space Gaining.

    Science.gov (United States)

    Verma, Sanjeev; Bhupali, Nameksh Raj; Gupta, Deepak Kumar; Singh, Sombir; Singh, Satinder Pal

    2018-01-01

    Space gaining is frequently required in orthodontics. Multiple loops were initially used for space gaining and alignment. The most common used mechanics for space gaining is the use of nickel-titanium open coil springs. The disadvantage of nickel-titanium coil spring is that they cannot be used until the arches are well aligned to receive the stiffer stainless steel wires. Therefore, a new method of gaining space during initial alignment and leveling has been developed and named as sleeve push technique (SPT). The nickel-titanium wires, i.e. 0.012 inches and 0.014 inches along with archwire sleeve (protective tubing) can be used in a modified way to gain space along with alignment. This method helps in gaining space right from day 1 of treatment. The archwire sleeve and nickel-titanium wire in this new SPT act as a mutually synergistic combination and provide the orthodontist with a completely new technique for space opening.

  13. Laser pushing or pulling of absorbing airborne particles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chuji, E-mail: cw175@msstate.edu; Gong, Zhiyong [Mississippi State University, Starkville, Mississippi 39759 (United States); Pan, Yong-Le; Videen, Gorden [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)

    2016-07-04

    A single absorbing particle formed by carbon nanotubes in the size range of 10–50 μm is trapped in air by a laser trapping beam and concurrently illuminated by another laser manipulating beam. When the trapping beam is terminated, the movement of the particle controlled by the manipulating beam is investigated. We report our observations of light-controlled pushing and pulling motions. We show that the movement direction has little relationship with the particle size and manipulating beam's parameters but is dominated by the particle's orientation and morphology. With this observation, the controllable optical manipulation is now able to be generalized to arbitrary particles, including irregularly shaped absorbing particles that are shown in this work.

  14. Pushing Firm Boundaries through Research and Open Innovation

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2011-01-01

    In this paper we will exemplify open innovation through a university-industry collaboration called Mobile Home Center (MHC). We will demonstrate how the model by Chesbrough can be used as a tool for mapping out a research process and furthermore illustrate what kind of outcast such project can...... provide into the company and bring forward the effect it has inside a company when performing open innovation together with research partners. We seek to bring forward how performing university-research collaboration can also change the practices inside a company and thus push the firm boundaries in new...... directions. Rather than looking at the firm as something static we will demonstrate how Chesbrough’s model on Open Innovation can be used to illustrate the dynamics of a company’s boundaries through Open Innovation....

  15. Erratic Black Hole Regulates Itself

    Science.gov (United States)

    2009-03-01

    New results from NASA's Chandra X-ray Observatory have made a major advance in explaining how a special class of black holes may shut off the high-speed jets they produce. These results suggest that these black holes have a mechanism for regulating the rate at which they grow. Black holes come in many sizes: the supermassive ones, including those in quasars, which weigh in at millions to billions of times the mass of the Sun, and the much smaller stellar-mass black holes which have measured masses in the range of about 7 to 25 times the Sun's mass. Some stellar-mass black holes launch powerful jets of particles and radiation, like seen in quasars, and are called "micro-quasars". The new study looks at a famous micro-quasar in our own Galaxy, and regions close to its event horizon, or point of no return. This system, GRS 1915+105 (GRS 1915 for short), contains a black hole about 14 times the mass of the Sun that is feeding off material from a nearby companion star. As the material swirls toward the black hole, an accretion disk forms. This system shows remarkably unpredictable and complicated variability ranging from timescales of seconds to months, including 14 different patterns of variation. These variations are caused by a poorly understood connection between the disk and the radio jet seen in GRS 1915. Chandra, with its spectrograph, has observed GRS 1915 eleven times since its launch in 1999. These studies reveal that the jet in GRS 1915 may be periodically choked off when a hot wind, seen in X-rays, is driven off the accretion disk around the black hole. The wind is believed to shut down the jet by depriving it of matter that would have otherwise fueled it. Conversely, once the wind dies down, the jet can re-emerge. "We think the jet and wind around this black hole are in a sort of tug of war," said Joseph Neilsen, Harvard graduate student and lead author of the paper appearing in the journal Nature. "Sometimes one is winning and then, for reasons we don

  16. Observation of Blobs and Holes in the Boundary Plasma of EAST Tokamak

    DEFF Research Database (Denmark)

    Yan, Ning; Xu, Guosheng; Zhang, Wei

    2011-01-01

    Intermittent convective transport at the edge and in the scrape-off layer (SOL) of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first time inside the shear layer. The amplitude probability distribution function...

  17. Black hole evaporation: a paradigm

    International Nuclear Information System (INIS)

    Ashtekar, Abhay; Bojowald, Martin

    2005-01-01

    A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results: (i) resolution of the Schwarzschild singularity using quantum geometry methods and (ii) time evolution of black holes in the trapping and dynamical horizon frameworks. Quantum geometry effects introduce a major modification in the traditional spacetime diagram of black hole evaporation, providing a possible mechanism for recovery of information that is classically lost in the process of black hole formation. The paradigm is developed directly in the Lorentzian regime and necessary conditions for its viability are discussed. If these conditions are met, much of the tension between expectations based on spacetime geometry and structure of quantum theory would be resolved

  18. Axion-dilation black holes

    International Nuclear Information System (INIS)

    Kallosh, R.

    1993-01-01

    In this talk some essential features of stringy black holes are described. The author considers charged U(1) and U(1) x U(1) four-dimensional axion-dilaton black holes. The Hawking temperature and the entropy of all solutions are shown to be simple functions of the squares of supercharges, defining the positivity bounds. Spherically symmetric and multi black hole solutions are presented. The extreme solutions with zero entropy (holons) represent a ground state of the theory and are characterized by elementary dilaton, axion, electric, and magnetic charges. The attractive gravitational and axion-dilaton force is balanced by the repulsive electromagnetic force. The author discusses the possibility of splitting of nearly extreme black holes. 11 refs

  19. Holes in magneto electrostatic traps

    International Nuclear Information System (INIS)

    Jones, R.

    1996-01-01

    We observe that in magneto electrostatic confinement (MEC) devices the magnetic surfaces are not always equipotentials. The lack of symmetry in the equipotential surfaces can result in holes in MEC plasma traps. (author)

  20. Black holes by analytic continuation

    CERN Document Server

    Amati, Daniele

    1997-01-01

    In the context of a two-dimensional exactly solvable model, the dynamics of quantum black holes is obtained by analytically continuing the description of the regime where no black hole is formed. The resulting spectrum of outgoing radiation departs from the one predicted by the Hawking model in the region where the outgoing modes arise from the horizon with Planck-order frequencies. This occurs early in the evaporation process, and the resulting physical picture is unconventional. The theory predicts that black holes will only radiate out an energy of Planck mass order, stabilizing after a transitory period. The continuation from a regime without black hole formation --accessible in the 1+1 gravity theory considered-- is implicit in an S matrix approach and provides in this way a possible solution to the problem of information loss.

  1. Hole dephasing caused by hole-hole interaction in a multilayered black phosphorus.

    Science.gov (United States)

    Li, Lijun; Khan, Muhammad Atif; Lee, Yoontae; Lee, Inyeal; Yun, Sun Jin; Youn, Doo-Hyeb; Kim, Gil-Ho

    2017-11-01

    We study the magnetotransport of holes in a multilayered black phosphorus in a temperature range of 1.9 to 21.5 K. We observed a negative magnetoresistance at magnetic fields up to 1.5 T. This negative magetoresistance was analyzed by weak localization theory in diffusive regime. At the lowest temperature and the highest carrier density we found a phase coherence length of 48 nm. The linear temperature dependence of the dephasing rate shows that the hole-hole scattering processes with small energy transfer are the dominant contribution in breaking the carrier phase coherence.

  2. New regular black hole solutions

    International Nuclear Information System (INIS)

    Lemos, Jose P. S.; Zanchin, Vilson T.

    2011-01-01

    In the present work we consider general relativity coupled to Maxwell's electromagnetism and charged matter. Under the assumption of spherical symmetry, there is a particular class of solutions that correspond to regular charged black holes whose interior region is de Sitter, the exterior region is Reissner-Nordstroem and there is a charged thin-layer in-between the two. The main physical and geometrical properties of such charged regular black holes are analyzed.

  3. Black holes from extended inflation

    International Nuclear Information System (INIS)

    Hsu, S.D.H.; Lawrence Berkeley Lab., CA

    1990-01-01

    It is argued that models of extended inflation, in which modified Einstein gravity allows a graceful exit from the false vacuum, lead to copious production of black holes. The critical temperature of the inflationary phase transition must be >10 8 GeV in order to avoid severe cosmological problems in a universe dominated by black holes. We speculate on the possibility that the interiors of false vacuum regions evolve into baby universes. (orig.)

  4. Black holes and cosmic censorship

    International Nuclear Information System (INIS)

    Hiscock, W.A.

    1979-01-01

    It is widely accepted that the complete gravitational collapse of a body always yields a black hole, and that naked singularities are never produced (the cosmic censorship hypothesis). The local (or strong) cosmic censorship hypothesis states that singularities which are even locally naked (e.g., to an observer inside a black hole) are never produced. This dissertation studies the validity of these two conjectures. The Kerr-Newman metrics describes the black holes only when M 2 greater than or equal to Q 2 + P 2 , where M is the mass of the black hole, a = J/M its specific angular momentum, Q its electric charge, and P its magnetic charge. In the first part of this dissertation, the possibility of converting an extreme Kerr-Newman black hole (M 2 = a 2 + Q 2 + P 2 ) into a naked singularity by the accretion of test particles is considered. The motion of test particles is studied with a large angular momentum to energy ratio, and also test particles with a large charge to energy ratio. The final state is always found to be a black hole if the angular momentum, electric charge, and magnetic charge of the black hole are all much greater than the corresponding angular momentum, electric charge, and magnetic charge of the test particle. In Part II of this dissertation possible black hole interior solutions are studied. The Cauchy horizons and locally naked timelike singularities of the charged (and/or rotating) solutions are contrasted with the spacelike all-encompassing singularity of the Schwarzschild solution. It is determined which portions of the analytic extension of the Reissner-Nordstroem solution are relevant to realistic gravitational collapse

  5. Are Black Holes Elementary Particles?

    OpenAIRE

    Ha, Yuan K.

    2009-01-01

    Quantum black holes are the smallest and heaviest conceivable elementary particles. They have a microscopic size but a macroscopic mass. Several fundamental types have been constructed with some remarkable properties. Quantum black holes in the neighborhood of the Galaxy could resolve the paradox of ultra-high energy cosmic rays detected in Earth's atmosphere. They may also play a role as dark matter in cosmology.

  6. Dark information of black hole radiation raised by dark energy

    Science.gov (United States)

    Ma, Yu-Han; Chen, Jin-Fu; Sun, Chang-Pu

    2018-06-01

    The "lost" information of black hole through the Hawking radiation was discovered being stored in the correlation among the non-thermally radiated particles (Parikh and Wilczek, 2000 [31], Zhang et al., 2009 [16]). This correlation information, which has not yet been proved locally observable in principle, is named by dark information. In this paper, we systematically study the influences of dark energy on black hole radiation, especially on the dark information. Calculating the radiation spectrum in the existence of dark energy by the approach of canonical typicality, which is reconfirmed by the quantum tunneling method, we find that the dark energy will effectively lower the Hawking temperature, and thus makes the black hole has longer life time. It is also discovered that the non-thermal effect of the black hole radiation is enhanced by dark energy so that the dark information of the radiation is increased. Our observation shows that, besides the mechanical effect (e.g., gravitational lensing effect), the dark energy rises the stored dark information, which could be probed by a non-local coincidence measurement similar to the coincidence counting of the Hanbury-Brown-Twiss experiment in quantum optics.

  7. High energy colliders as black hole factories: The end of short distance physics

    International Nuclear Information System (INIS)

    Giddings, Steven B.; Thomas, Scott

    2002-01-01

    If the fundamental Planck scale is of order of a TeV, as is the case in some extra-dimension scenarios, future hadron colliders such as the CERN Large Hadron Collider will be black hole factories. The nonperturbative process of black hole formation and decay by Hawking evaporation gives rise to spectacular events with up to many dozens of relatively hard jets and leptons with a characteristic ratio of hadronic to leptonic activity of roughly 5:1. The total transverse energy of such events is typically a sizable fraction of the beam energy. Perturbative hard scattering processes at energies well above the Planck scale are cloaked behind a horizon, thus limiting the ability to probe short distances. The high energy black hole cross section grows with energy at a rate determined by the dimensionality and geometry of the extra dimensions. This dependence therefore probes the extra dimensions at distances larger than the Planck scale

  8. Tests for the existence of black holes through gravitational wave echoes

    Science.gov (United States)

    Cardoso, Vitor; Pani, Paolo

    2017-09-01

    The existence of black holes and spacetime singularities is a fundamental issue in science. Despite this, observations supporting their existence are scarce, and their interpretation is unclear. In this Perspective we outline the case for black holes that has been made over the past few decades, and provide an overview of how well observations adjust to this paradigm. Unsurprisingly, we conclude that observational proof for black holes is, by definition, impossible to obtain. However, just like Popper's black swan, alternatives can be ruled out or confirmed to exist with a single observation. These observations are within reach. In the coming years and decades, we will enter an era of precision gravitational-wave physics with more sensitive detectors. Just as accelerators have required larger and larger energies to probe smaller and smaller scales, more sensitive gravitational-wave detectors will probe regions closer and closer to the horizon, potentially reaching Planck scales and beyond. What may be there, lurking?

  9. Measurement of the magnetic field inside the holes of a drilled bulk high-Tc superconductor

    Science.gov (United States)

    Lousberg, Gregory P.; Fagnard, Jean-François; Noudem, Jacques G.; Ausloos, Marcel; Vanderheyden, Benoit; Vanderbemden, Philippe

    2009-04-01

    We use macroscopic holes drilled in a bulk YBCO superconductor to probe its magnetic properties in the volume of the sample. The sample is subjected to an AC magnetic flux with a density ranging from 30 to 130 mT and the flux in the superconductor is probed by miniature coils inserted in the holes. In a given hole, three different penetration regimes can be observed: (i) the shielded regime, where no magnetic flux threads the hole; (ii) the gradual penetration regime, where the waveform of the magnetic field has a clipped sine shape whose fundamental component scales with the applied field; and (iii) the flux concentration regime, where the waveform of the magnetic field is nearly a sine wave, with an amplitude exceeding that of the applied field by up to a factor of two. The distribution of the penetration regimes in the holes is compared with that of the magnetic flux density at the top and bottom surfaces of the sample, and is interpreted with the help of optical polarized light micrographs of these surfaces. We show that the measurement of the magnetic field inside the holes can be used as a local characterization of the bulk magnetic properties of the sample.

  10. Black holes in the universe

    International Nuclear Information System (INIS)

    Camenzind, M.

    2005-01-01

    While physicists have been grappling with the theory of black holes (BH), as shown by the many contributions to the Einstein year, astronomers have been successfully searching for real black holes in the Universe. Black hole astrophysics began in the 1960s with the discovery of quasars and other active galactic nuclei (AGN) in distant galaxies. Already in the 1960s it became clear that the most natural explanation for the quasar activity is the release of gravitational energy through accretion of gas onto supermassive black holes. The remnants of this activity have now been found in the centers of about 50 nearby galaxies. BH astrophysics received a new twist in the 1970s with the discovery of the X-ray binary (XRB) Cygnus X-1. The X-ray emitting compact object was too massive to be explained by a neutron star. Today, about 20 excellent BH candidates are known in XRBs. On the extragalactic scale, more than 100.000 quasars have been found in large galaxy surveys. At the redshift of the most distant ones, the Universe was younger than one billion year. The most enigmatic black hole candidates identified in the last years are the compact objects behind the Gamma-Ray Bursters. The formation of all these types of black holes is accompanied by extensive emission of gravitational waves. The detection of these strong gravity events is one of the biggest challenges for physicists in the near future. (author)

  11. Stationary black holes as holographs

    Energy Technology Data Exchange (ETDEWEB)

    Racz, Istvan [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-01 (Japan); MTA KFKI, Reszecske- es Magfizikai Kutatointezet, H-1121 Budapest, Konkoly Thege Miklos ut 29-33 (Hungary)

    2007-11-21

    Smooth spacetimes possessing a (global) one-parameter group of isometries and an associated Killing horizon in Einstein's theory of gravity are investigated. No assumption concerning the asymptotic structure is made; thereby, the selected spacetimes may be considered as generic distorted stationary black holes. First, spacetimes of arbitrary dimension, n {>=} 3, with matter satisfying the dominant energy condition and allowing a non-zero cosmological constant are investigated. In this part, complete characterization of the topology of the event horizon of 'distorted' black holes is given. It is shown that the topology of the event horizon of 'distorted' black holes is allowed to possess a much larger variety than that of the isolated black hole configurations. In the second part, four-dimensional (non-degenerate) electrovac distorted black hole spacetimes are considered. It is shown that the spacetime geometry and the electromagnetic field are uniquely determined in the black hole region once the geometry of the bifurcation surface and one of the electromagnetic potentials are specified there. Conditions guaranteeing the same type of determinacy, in a neighbourhood of the event horizon, on the domain of outer communication side are also investigated. In particular, they are shown to be satisfied in the analytic case.

  12. Atomic structure in black hole

    International Nuclear Information System (INIS)

    Nagatani, Yukinori

    2006-01-01

    We propose that any black hole has atomic structure in its inside and has no horizon as a model of black holes. Our proposal is founded on a mean field approximation of gravity. The structure of our model consists of a (charged) singularity at the center and quantum fluctuations of fields around the singularity, namely, it is quite similar to that of atoms. Any properties of black holes, e.g. entropy, can be explained by the model. The model naturally quantizes black holes. In particular, we find the minimum black hole, whose structure is similar to that of the hydrogen atom and whose Schwarzschild radius is approximately 1.1287 times the Planck length. Our approach is conceptually similar to Bohr's model of the atomic structure, and the concept of the minimum Schwarzschild radius is similar to that of the Bohr radius. The model predicts that black holes carry baryon number, and the baryon number is rapidly violated. This baryon number violation can be used as verification of the model. (author)

  13. The 2002 Antarctic Ozone Hole

    Science.gov (United States)

    Newman, P. A.; Nash, E. R.; Douglass, A. R.; Kawa, S. R.

    2003-01-01

    Since 1979, the ozone hole has grown from near zero size to over 24 Million km2. This area is most strongly controlled by levels of inorganic chlorine and bromine oncentrations. In addition, dynamical variations modulate the size of the ozone hole by either cooling or warming the polar vortex collar region. We will review the size observations, the size trends, and the interannual variability of the size. Using a simple trajectory model, we will demonstrate the sensitivity of the ozone hole to dynamical forcing, and we will use these observations to discuss the size of the ozone hole during the 2002 Austral spring. We will further show how the Cly decreases in the stratosphere will cause the ozone hole to decrease by 1-1.5% per year. We will also show results from a 3-D chemical transport model (CTM) that has been continuously run since 1999. These CTM results directly show how strong dynamics acts to reduce the size of the ozone hole.

  14. Intermediate-Mass Black Holes

    Science.gov (United States)

    Miller, M. Coleman; Colbert, E. J. M.

    2004-01-01

    The mathematical simplicity of black holes, combined with their links to some of the most energetic events in the universe, means that black holes are key objects for fundamental physics and astrophysics. Until recently, it was generally believed that black holes in nature appear in two broad mass ranges: stellar-mass (M~3 20 M⊙), which are produced by the core collapse of massive stars, and supermassive (M~106 1010 M⊙), which are found in the centers of galaxies and are produced by a still uncertain combination of processes. In the last few years, however, evidence has accumulated for an intermediate-mass class of black holes, with M~102 104 M⊙. If such objects exist they have important implications for the dynamics of stellar clusters, the formation of supermassive black holes, and the production and detection of gravitational waves. We review the evidence for intermediate-mass black holes and discuss future observational and theoretical work that will help clarify numerous outstanding questions about these objects.

  15. Black hole quantum spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Corda, Christian [Institute for Theoretical Physics and Advanced Mathematics (IFM) Einstein-Galilei, Prato (Italy); Istituto Universitario di Ricerca ' ' Santa Rita' ' , Prato (Italy); International Institute for Applicable Mathematics and Information Sciences (IIAMIS), Hyderabad (India)

    2013-12-15

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re-analysed BH quasi-normal modes (QNMs) and interpreted them naturally in terms of quantum levels. In this work we improve such an analysis removing some approximations that have been implicitly used in our previous works and obtaining the corrected expressions for the formulas of the horizon's area quantization and the number of quanta of area and hence also for Bekenstein-Hawking entropy, its subleading corrections and the number of micro-states, i.e. quantities which are fundamental to realize the underlying quantum gravity theory, like functions of the QNMs quantum ''overtone'' number n and, in turn, of the BH quantum excited level. An approximation concerning the maximum value of n is also corrected. On the other hand, our previous results were strictly corrected only for scalar and gravitational perturbations. Here we show that the discussion holds also for vector perturbations. The analysis is totally consistent with the general conviction that BHs result in highly excited states representing both the ''hydrogen atom'' and the ''quasi-thermal emission'' in quantum gravity. Our BH model is somewhat similar to the semi-classical Bohr's model of the structure of a hydrogen atom. The thermal approximation of previous results in the literature is consistent with the results in this paper. In principle, such results could also have important implications for the BH information paradox. (orig.)

  16. Black hole quantum spectrum

    Science.gov (United States)

    Corda, Christian

    2013-12-01

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re-analysed BH quasi-normal modes (QNMs) and interpreted them naturally in terms of quantum levels. In this work we improve such an analysis removing some approximations that have been implicitly used in our previous works and obtaining the corrected expressions for the formulas of the horizon's area quantization and the number of quanta of area and hence also for Bekenstein-Hawking entropy, its subleading corrections and the number of micro-states, i.e. quantities which are fundamental to realize the underlying quantum gravity theory, like functions of the QNMs quantum "overtone" number n and, in turn, of the BH quantum excited level. An approximation concerning the maximum value of n is also corrected. On the other hand, our previous results were strictly corrected only for scalar and gravitational perturbations. Here we show that the discussion holds also for vector perturbations. The analysis is totally consistent with the general conviction that BHs result in highly excited states representing both the "hydrogen atom" and the "quasi-thermal emission" in quantum gravity. Our BH model is somewhat similar to the semi-classical Bohr's model of the structure of a hydrogen atom. The thermal approximation of previous results in the literature is consistent with the results in this paper. In principle, such results could also have important implications for the BH information paradox.

  17. Black Hole Complementary Principle and Noncommutative Membrane

    International Nuclear Information System (INIS)

    Wei Ren

    2006-01-01

    In the spirit of black hole complementary principle, we have found the noncommutative membrane of Scharzchild black holes. In this paper we extend our results to Kerr black hole and see the same story. Also we make a conjecture that spacetimes are noncommutative on the stretched membrane of the more general Kerr-Newman black hole.

  18. 30 CFR 57.9360 - Shelter holes.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Shelter holes. 57.9360 Section 57.9360 Mineral....9360 Shelter holes. (a) Shelter holes shall be— (1) Provided at intervals adequate to assure the safety... farthest projection of moving equipment. (b) Shelter holes shall not be used for storage unless a 40-inch...

  19. Formation and Coalescence of Electron Solitary Holes

    DEFF Research Database (Denmark)

    Saeki, K.; Michelsen, Poul; Pécseli, H. L.

    1979-01-01

    Electron solitary holes were observed in a magnetized collisionless plasma. These holes were identified as Bernstein-Green-Kruskal equilibria, thus being purely kinetic phenomena. The electron hole does not damp even though its velocity is close to the electron thermal velocity. Two holes attract...

  20. 30 CFR 77.1010 - Collaring holes.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Collaring holes. 77.1010 Section 77.1010... Control § 77.1010 Collaring holes. (a) Starter steels shall be used when collaring holes with hand-held drills. (b) Men shall not hold the drill steel while collaring holes, or rest their hands on the chuck or...

  1. Accretion, primordial black holes and standard cosmology

    Indian Academy of Sciences (India)

    Primordial black holes evaporate due to Hawking radiation. We find that the evaporation times of primordial black holes increase when accretion of radiation is included. Thus, depending on accretion efficiency, more primordial black holes are existing today, which strengthens the conjecture that the primordial black holes ...

  2. Testing the frost resistance of backfilling materials for geothermal heat probes; Pruefung der Frostbestaendigkeit von Verfuellmassen fuer Erdwaermesonden

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Tobias; Schnell, Kurt [HDG Umwelttechnik GmbH, Kisslegg (Germany)

    2011-07-01

    Groundwater protection, general operational safety and the reliable operation over many years are the key factors in the use of geothermal probes. Backfilling materials with which probes are pressed in the hole meet these requirements. For several years, manufacturers and researchers devote a great attention to the issue of an adequate freeze-thaw resistance of these components.

  3. Comparison of delayed versus immediate pushing during second stage of labor for nulliparous women with epidural anesthesia.

    Science.gov (United States)

    Gillesby, Erica; Burns, Suzan; Dempsey, Amy; Kirby, Shirley; Mogensen, Kami; Naylor, Kelly; Petrella, Joann; Vanicelli, Rebecca; Whelan, Breon

    2010-01-01

    To determine if the use of delayed pushing after the onset of the second stage of labor decreases the time of active pushing and decreases maternal fatigue. Randomized clinical trial. Labor and delivery unit of a not-for-profit community hospital. Convenience sample of nulliparous laboring women with epidural anesthesia. Immediate or delayed pushing (2 hours) during the second stage of labor at the time of complete cervical dilatation. The length of pushing, total length of the second stage, and maternal fatigue. A total of 77 women were studied (immediate pushing group=39; delayed pushing=38). The immediate pushing group averaged 94 (± 57) minutes in active pushing, while the delayed pushing group averaged 68 (± 46) minutes, a statistically significant difference (p=.04). No significant differences were found in fatigue scores between the immediate and delayed pushing groups (p>.05). We found that by delaying the onset of active pushing for 2 hours after the beginning of the second stage of labor, the time that nulliparous women with epidural anesthesia spent in active pushing was significantly decreased by 27%. Although the delayed pushing group rested for up to 2 hours, the total time in the second stage of labor averaged only 59 minutes longer than the immediate pushing group. © 2010 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

  4. Black Hole Caught Zapping Galaxy into Existence?

    Science.gov (United States)

    2009-11-01

    equivalent to about 350 Suns per year, one hundred times more than rates for typical galaxies in the local Universe. Earlier observations had shown that the companion galaxy is, in fact, under fire: the quasar is spewing a jet of highly energetic particles towards its companion, accompanied by a stream of fast-moving gas. The injection of matter and energy into the galaxy indicates that the quasar itself might be inducing the formation of stars and thereby creating its own host galaxy; in such a scenario, galaxies would have evolved from clouds of gas hit by the energetic jets emerging from quasars. "The two objects are bound to merge in the future: the quasar is moving at a speed of only a few tens of thousands of km/h with respect to the companion galaxy and their separation is only about 22 000 light-years," says Elbaz. "Although the quasar is still 'naked', it will eventually be 'dressed' when it merges with its star-rich companion. It will then finally reside inside a host galaxy like all other quasars." Hence, the team have identified black hole jets as a possible driver of galaxy formation, which may also represent the long-sought missing link to understanding why the mass of black holes is larger in galaxies that contain more stars [3]. "A natural extension of our work is to search for similar objects in other systems," says Jahnke. Future instruments, such as the Atacama Large Millimeter/submillimeter Array, the European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope will be able to search for such objects at even larger distances from us, probing the connection between black holes and the formation of galaxies in the more distant Universe. Notes [1] Supermassive black holes are found in the cores of most large galaxies; unlike the inactive and starving one sitting at the centre of the Milky Way, a fraction of them are said to be active, as they eat up enormous amounts of material. These frantic actions produce a copious release of energy

  5. Probe tests microweld strength

    Science.gov (United States)

    1965-01-01

    Probe is developed to test strength of soldered, brazed or microwelded joints. It consists of a spring which may be adjusted to the desired test pressure by means of a threaded probe head, and an indicator lamp. Device may be used for electronic equipment testing.

  6. Magnetic susceptibility measuring probe utilizing a compensation coil

    International Nuclear Information System (INIS)

    Bonnet, Jean; Fournet, Julien.

    1978-01-01

    This invention concerns a magnetic susceptibility measuring probe. It is used, inter alia, in logging, to wit continuous logging of the magnetic susceptibility of the ground throughout the length of a bore hole. The purpose of this invention is to increase the sensitivity of this type of probe by creating a side focusing effect . To this end, it provides for the use of a compensation winding, coaxial with the measurement winding and arranged symmetrically to the latter with respect to the centre of the induction windings [fr

  7. Alternate Explosions: Collapse and Accretion Events with Red Holes instead of Black Holes

    OpenAIRE

    Graber, James S.

    1999-01-01

    A red hole is "just like a black hole" except it lacks an event horizon and a singularity. As a result, a red hole emits much more energy than a black hole during a collapse or accretion event. We consider how a red hole solution can solve the "energy crisis" and power extremely energetic gamma ray bursts and hypernovae.

  8. The push factors of intra-urban residential mobility in Calabar, Nigeria

    African Journals Online (AJOL)

    The paper takes a critical look at the push factors of intra-urban residential mobility in Calabar. Push factors are defined as those which operate to induce or encourage households to change their residence in the city. The paper notes that changing of residence by urban households in Western cities is a common ...

  9. Educational Exclusion: Drop Out, Push Out, and School-to-Prison Pipeline among LGBTQ Youth

    Science.gov (United States)

    Gay, Lesbian and Straight Education Network (GLSEN), 2016

    2016-01-01

    "Educational Exclusion: Drop Out, Push Out, and the School-to-Prison Pipeline among LGBTQ Youth" provides an in-depth look at the conditions that effectively push LGBTQ youth out of school and potentially into the criminal justice system. The report provides specific, real world guidance to address the hostile school climates and…

  10. On Reducing Delay in Mesh-Based P2P Streaming: A Mesh-Push Approach

    Science.gov (United States)

    Liu, Zheng; Xue, Kaiping; Hong, Peilin

    The peer-assisted streaming paradigm has been widely employed to distribute live video data on the internet recently. In general, the mesh-based pull approach is more robust and efficient than the tree-based push approach. However, pull protocol brings about longer streaming delay, which is caused by the handshaking process of advertising buffer map message, sending request message and scheduling of the data block. In this paper, we propose a new approach, mesh-push, to address this issue. Different from the traditional pull approach, mesh-push implements block scheduling algorithm at sender side, where the block transmission is initiated by the sender rather than by the receiver. We first formulate the optimal upload bandwidth utilization problem, then present the mesh-push approach, in which a token protocol is designed to avoid block redundancy; a min-cost flow model is employed to derive the optimal scheduling for the push peer; and a push peer selection algorithm is introduced to reduce control overhead. Finally, we evaluate mesh-push through simulation, the results of which show mesh-push outperforms the pull scheduling in streaming delay, and achieves comparable delivery ratio at the same time.

  11. Push plate, mounting assembly, circuit board, and method of assembling thereof for ball grid array packages

    Science.gov (United States)

    Vaughn, Mark R.; Montague, Stephen

    2017-05-16

    A push plate that includes springs in the form of cantilever flexures and an inspection window is disclosed. The push plate provides a known, uniform, down force and minimal torque to a package to be tested. The cantilevers have a known, calculable down force producing stiffness. The window provides for viewing of the package during testing.

  12. Quantifying muscle patterns and spine load during various forms of the push-up.

    Science.gov (United States)

    Freeman, Stephanie; Karpowicz, Amy; Gray, John; McGill, Stuart

    2006-03-01

    This study was conducted to quantify the normalized amplitudes of the abdominal wall and back extensor musculature during a variety of push-up styles. We also sought to quantify their impact on spinal loading by calculating spinal compression and torque generation in the L4-5 area. Ten university-age participants, nine males and one female, in good to excellent condition, volunteered to participate in this study. All participants were requested to perform a maximum of 12 different push-up exercises, three trials per exercise. Surface electromyographic data (EMG) were collected bilaterally on rectus abdominis, external oblique, internal oblique, latissimus dorsi, and erector spinae muscles, and unilaterally (right side) on pectoralis major, triceps brachii, biceps brachii, and anterior deltoid muscles. Spine kinetics were obtained using an anatomically detailed model of the torso/spine. This study revealed that more dynamic push-ups (i.e., ballistic, with hand movement) required more muscle activation and higher spine load, whereas placing labile balls under the hands only resulted in modest increases in spine load. Right rectus abdominis (RA) activation was significantly higher than left RA activation during the left hand forward push-up and vice versa for the right hand forward push-up (P push-ups (P push-up resulted in the highest spine compression. Skilled participants showed greater synchronicity with peak muscle activation (plyometric type of contractions) during ballistic push-ups. These data will help guide exercise selection for individuals with differing training objectives and injury history.

  13. Optimal regenerative braking with a push-belt CVT: an experimental study

    NARCIS (Netherlands)

    Berkel, van K.; Hofman, T.; Vroemen, B.G.; Steinbuch, M.

    2010-01-01

    This paper describes the approach and the results of efficiency experiments on a push-belt Continuously Variable Transmission (CVT) in a new hybrid drive train. The hybrid drive train uses the push-belt CVT to charge a flywheel, with the kinetic energy of the vehicle during regenerative braking and

  14. Optimal regenerative braking with a push-belt CVT : an experimental study

    NARCIS (Netherlands)

    van Berkel, K.; Hofman, T.; Vroemen, B.; Steinbuch, M.

    2010-01-01

    This paper describes the approach and the results of efficiency experiments on a push-belt Continuously Variable Transmission (CVT) in a new hybrid drive train. The hybrid drive train uses the push-belt CVT to “charge” a flywheel, with the kinetic energy of the vehicle during regenerative braking

  15. Beyond Knut Holt's fusion model, balancing market pull and technology push

    NARCIS (Netherlands)

    Nagel, A.P.

    2003-01-01

    Should a firm rely on market pull or on technology push? Some scholars have extreme opinions on this and firms do switch emphasis on push and pull over time. Knut Holt, the first president of ISPIM, presented his so-called Fusion Model in the early 1970s to shed light onto this debate. This paper

  16. Muscular contribution to low-back loading and stiffness during standard and suspended push-ups.

    Science.gov (United States)

    Beach, Tyson A C; Howarth, Samuel J; Callaghan, Jack P

    2008-06-01

    Push-up exercises are normally performed to challenge muscles that span upper extremity joints. However, it is also recognized that push-ups provide an effective abdominal muscle challenge, especially when the hands are in contact with a labile support surface. The purpose of this study was to compare trunk muscle activation levels and resultant intervertebral joint (IVJ) loading when standard and suspended push-ups were performed, and to quantify and compare the contribution of trunk muscles to IVJ rotational stiffness in both exercises. Eleven recreationally trained male volunteers performed sets of standard and suspended push-ups. Upper body kinematic, kinetic, and EMG data were collected and input into a 3D biomechanical model of the lumbar torso to quantify lumbar IVJ loading and the contributions of trunk muscles to IVJ rotational stiffness. When performing suspended push-ups, muscles of the abdominal wall and the latissimus dorsi were activated to levels that were significantly greater than those elicited when performing standard push-ups (ppush-ups. Also directly resulting from the increased activation levels of the abdominal muscles and the latissimus dorsi during suspended push-ups was increased muscular contribution to lumbar IVJ rotational stiffness (ppush-ups appear to provide a superior abdominal muscle challenge. However, for individuals unable to tolerate high lumbar IVJ compressive loads, potential benefits gained by incorporating suspended push-ups into their resistance training regimen may be outweighed by the risk of overloading low-back tissues.

  17. Push-Pull Ventilation in a Painting Shop for Large Steel Constructions

    DEFF Research Database (Denmark)

    Svidt, Kjeld; Heiselberg, Per

    This paper describes the analysis of a push-pull ventilation system for a painting shop that is used for painting steel chimneys and windmill towers.......This paper describes the analysis of a push-pull ventilation system for a painting shop that is used for painting steel chimneys and windmill towers....

  18. Positive Harris recurrence and diffusion scale analysis of a push pull queueing network

    NARCIS (Netherlands)

    Nazarathy, J.; Weiss, G.

    2010-01-01

    We consider a push pull queueing network with two servers and two types of job which are processed by the two servers in opposite order, with stochastic generally distributed processing times. This push pull network was introduced by Kopzon and Weiss, who assumed exponential processing times. It is

  19. What Explains the Survival Gap of Pushed and Pulled Corporate Spin-offs?

    DEFF Research Database (Denmark)

    Rocha, Vera; Carneiro, Anabela; Varum, Celeste

    2015-01-01

    Unconditionally, pushed spin-offs are found to survive longer than their pulled counterparts. Using matched employer-employee data and novel multivariate decomposition techniques, we show that pushed spin-offs’ relative survival advantage is mostly explained by their larger human capital endowments...

  20. Low-back and shoulder complaints among workers with pushing and pulling tasks

    NARCIS (Netherlands)

    Hoozemans, Marco J. M.; van der Beek, Allard J.; Fring-Dresen, Monique H. W.; van der Woude, Luc H. V.; van Dijk, Frank J. H.

    2002-01-01

    Objectives Low-back and shoulder complaints were examined in relation to self-reported and objectively assessed exposure to work-related pushing and pulling. Methods Workers from several companies (eg, nursing homes and flower auctions) with pushing and pulling tasks and, as reference, workers

  1. Spontaneous pushing to prevent postpartum urinary incontinence: a randomized, controlled trial.

    Science.gov (United States)

    Low, Lisa Kane; Miller, Janis M; Guo, Ying; Ashton-Miller, James A; DeLancey, John O L; Sampselle, Carolyn M

    2013-03-01

    The risk for urinary incontinence can be 2.6-fold greater in women after pregnancy and childbirth compared with their never-pregnant counterparts, with the incidence increasing with parity. We tested the hypothesis that the incidence of de novo postpartum urinary incontinence in primiparous women is reduced with the use of spontaneous pushing alone or in combination with perineal massage compared with women who experienced traditional directed pushing for second-stage management. This was a prospective clinical trial enrolling and randomizing 249 women into a four-group design: (1) routine care with coached or directed pushing, (2) spontaneous self-directed pushing, (3) prenatal perineal massage initiated in the third trimester, and (4) the combination of spontaneous pushing plus perineal massage. Self-report of incontinence was assessed using analysis of variance (ANOVA) and covariance (ANCOVA) models in 145 remaining women at 12 months postpartum using the Leakage Index, which is sensitive to minor leakage. No statistical difference in the incidence of de novo postpartum incontinence was found based on method of pushing (spontaneous/directed) (P value = 0.57) or in combination with prenatal perineal massage (P value = 0.57). Fidelity to pushing treatment of type was assessed and between-groups crossover detected. Spontaneous pushing did not reduce the incidence of postpartum incontinence experienced by women 1 year after their first birth due to high cross-over between randomization groups.

  2. Force direction in pushing and pulling and Musculo-Skeletal load

    NARCIS (Netherlands)

    Looze, M.P. de; Kuijer, P.P.F.M.

    1999-01-01

    In pushing and pulling wheeled objects, the effect of the exerted force on local musculo-skeletal loads depends on the direction of force exertion. Several questions about the direction of force exertion in pushing and pulling, the effects of handle height and force level on force direction, and the

  3. Regular black hole in three dimensions

    OpenAIRE

    Myung, Yun Soo; Yoon, Myungseok

    2008-01-01

    We find a new black hole in three dimensional anti-de Sitter space by introducing an anisotropic perfect fluid inspired by the noncommutative black hole. This is a regular black hole with two horizons. We compare thermodynamics of this black hole with that of non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy.

  4. Statistics of structural holes in the one-component classical plasma near freezing

    International Nuclear Information System (INIS)

    Cardenas, M.; Tosi, M.P.

    1998-03-01

    The correlations between structural holes in the fluid phase of the one-component classical plasma near its freezing point at coupling strength Γ=179 are studied by a statistical method using the Ornstein-Zernike relations for a partly quenched disordered system in combination with the hypernetted chain closure. The method involves inserting in the quenched structure of the plasma variable numbers of point-like charged particles, which on reaching equilibrium probe the holes in the matrix. When the probes carry the same charge as the plasma particles, the results may also be interpreted as describing the evolution of the correlations between annealed particles in a partly quenched disordered plasma upon varying the fraction of quenched particles at constant total density. Doubling the charge carried by the probes sharpens their correlations and improves the resolution that can be obtained in this method of structural analysis. (author)

  5. Technology and trend management at the interface of technology push and market pull

    DEFF Research Database (Denmark)

    Maier, Maximilian; Hofmann, Maximilian; Brem, Alexander

    2016-01-01

    Technology push and market pull innovation strategies are playing an important role for the effective management of ideas, technologies, and trends. The coexistence of these two approaches led to many debates and the focus switched several times from putting more effort into technology push aspects...... to fostering market pull approaches in the last decades. Still, there is no in-depth exploration of the interface of technology push and market pull and only few conceptual models are dealing with the connection between technology push and market pull in particular. Therefore, this study puts an exploratory...... focus on the innovation management processes of a global outdoor manufacturer with a special emphasis on the interface between technology push and market pull. From the case findings and our literature we conceptualise a non-linear innovation model that systematically integrates market pull...

  6. Observing the contour profile of a Kerr-Sen black hole

    Science.gov (United States)

    Lan, X. G.; Pu, J.

    2018-06-01

    In this paper, the shadow and the corresponding naked singularity cast by a Kerr-Sen black hole are studied. It is found that the shadow of a rotating black hole would be a dark zone surrounded by a deformed circle, and the shadow is distorted more away from a circle when the black hole approaches the extremal case. Besides, it is shown that the mean radius of the shadow decreases and distortion parameter increases with the increasing of charge, respectively. However, the mean radius and the distortion parameter vary complicatedly with the change of spin parameter. In the beginning, both observables decrease rapidly with the increasing of specific angular momentum, nevertheless, they increase slightly in the latter part. These results show that there would be a significant effect of the spin on the shadows, which would be of great importance for probing the nature of the black hole.

  7. Aharonov–Bohm protection of black hole's baryon/skyrmion hair

    Energy Technology Data Exchange (ETDEWEB)

    Dvali, Gia [Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität, 80333 München (Germany); Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Gußmann, Alexander, E-mail: alexander.gussmann@physik.uni-muenchen.de [Arnold-Sommerfeld-Center for Theoretical Physics, Ludwig-Maximilians-Universität, 80333 München (Germany)

    2017-05-10

    The baryon/skyrmion correspondence implies that the baryon number is encoded into a topological surface integral. Under certain conditions that we clarify, this surface integral can be measured by an asymptotic observer in form of an Aharonov–Bohm phase-shift in an experiment in which the skyrmion passes through a loop of a probe string. In such a setup the baryon/skyrmion number must be respected by black holes, despite the fact that it produces no long-range classical field. If initially swallowed by a black hole, the baryon number must resurface in form of a classical skyrmion hair, after the black hole evaporates below a certain critical size. Needless to say, the respect of the baryon number by black holes is expected to have potentially-interesting astrophysical consequences.

  8. EFFECT OF PILOT HOLE TAPPING ON PULLOUT STRENGTH AND INSERTION TORQUE OF DUAL CORE PEDICLE SCREWS.

    Science.gov (United States)

    Rosa, Rodrigo César; Silva, Patrícia; Falcai, Maurício José; Shimano, Antônio Carlos; Defino, Helton Luiz Aparecido

    2010-01-01

    To evaluate the influence of pilot hole tapping on pullout resistance and insertion torque of pedicle screws with a conical core. Mechanical tests using a universal testing machine were performed on pedicle screws with a conical core that were inserted into pedicles in the fifth lumbar vertebra of calves. The insertion torque was measured using a torque meter with a capacity of 10 Nm, which was considered to be the highest torque value. The pilot holes were prepared using a probe of external diameter 3.8 mm and tapping of the same dimensions and thread characteristics as the screw. Decreased insertion torque and pullout resistance were observed in the group with prior tapping of the pilot hole. Pilot hole tapping reduced the insertion torque and pullout resistance of pedicle screws with a conical core that had been inserted into the pedicle of the fifth lumbar vertebra of calves.

  9. Aharonov–Bohm protection of black hole's baryon/skyrmion hair

    Directory of Open Access Journals (Sweden)

    Gia Dvali

    2017-05-01

    Full Text Available The baryon/skyrmion correspondence implies that the baryon number is encoded into a topological surface integral. Under certain conditions that we clarify, this surface integral can be measured by an asymptotic observer in form of an Aharonov–Bohm phase-shift in an experiment in which the skyrmion passes through a loop of a probe string. In such a setup the baryon/skyrmion number must be respected by black holes, despite the fact that it produces no long-range classical field. If initially swallowed by a black hole, the baryon number must resurface in form of a classical skyrmion hair, after the black hole evaporates below a certain critical size. Needless to say, the respect of the baryon number by black holes is expected to have potentially-interesting astrophysical consequences.

  10. Wilson loop's phase transition probed by non-local observable

    Directory of Open Access Journals (Sweden)

    Hui-Ling Li

    2018-04-01

    Full Text Available In order to give further insights into the holographic Van der Waals phase transition, it would be of great interest to investigate the behavior of Wilson loop across the holographic phase transition for a higher dimensional hairy black hole. We offer a possibility to proceed with a numerical calculation in order to discussion on the hairy black hole's phase transition, and show that Wilson loop can serve as a probe to detect a phase structure of the black hole. Furthermore, for a first order phase transition, we calculate numerically the Maxwell's equal area construction; and for a second order phase transition, we also study the critical exponent in order to characterize the Wilson loop's phase transition.

  11. Uranium investigation in an alluvial aquifer with direct push methods - 59281

    International Nuclear Information System (INIS)

    De Weirdt, Fabian

    2012-01-01

    Document available in abstract form only. Full text of publication follows: The U.S. EPA has established a maximum contaminant level of 30 ug/l for uranium in drinking water due to its toxicity as a heavy metal. This regulation has affected many small public water supply systems in the US and several of them are struggling to come into compliance with the new standard. One such community is Clarks, NE, US which is situated on the alluvial deposits of the Platte River that are underlain by the Cretaceous Age Niobrara formation. Geoprobe Systems coordinated with the Nebraska Dept. of Health and Human Services, Water Well Stds. Program to investigate the cause of the elevated uranium in the groundwater that supplies drinking water to the village of Clarks. Initially hydraulic profiling tool (HPT) logs were obtained at selected locations across the Clarks well field. The HPT probe was advanced to depths of almost 36 m (120 ft) at several locations and the logs provided detailed information about the hydro-stratigraphy of the local aquifer not available from the drillers logs. The HPT logs were used to guide selection of screen depths for small diameter wells that were installed with direct push (DP) methods. A total of nine wells were installed at two locations at the facility with well depths ranging from as little as 6 m (20 ft) to a maximum of 36 m (118 ft). All wells were grouted bottom-up with a tremie tube using 25% solids bentonite slurry to assure screen interval isolation. (author)

  12. Probing nonlinear electrodynamics in slowly rotating spacetimes through neutrino astrophysics

    OpenAIRE

    Cuesta, Herman J. Mosquera; Lambiase, Gaetano; Pereira, Jonas P.

    2017-01-01

    Huge electromagnetic fields are known to be present during the late stages of the dynamics of supernovae. Thus, when dealing with electrodynamics in this context, the possibility may arise to probe nonlinear theories (generalizations of the Maxwellian electromagnetism). We firstly solve Einstein field equations minimally coupled to an arbitrary (current-free) nonlinear Lagrangian of electrodynamics (NLED) in the slow rotation regime $a\\ll M$ (black hole's mass), up to first order in $a/M$. We...

  13. Measuring spacetime: from the big bang to black holes.

    Science.gov (United States)

    Tegmark, Max

    2002-05-24

    Space is not a boring static stage on which events unfold over time, but a dynamic entity with curvature, fluctuations, and a rich life of its own. Spectacular measurements of the cosmic microwave background, gravitational lensing, type Ia supernovae, large-scale structure, spectra of the Lyman alpha forest, stellar dynamics, and x-ray binaries are probing the properties of spacetime over 22 orders of magnitude in scale. Current measurements are consistent with an infinite flat everlasting universe containing about 30% cold dark matter, 65% dark energy, and at least two distinct populations of black holes.

  14. Black holes, qubits and octonions

    International Nuclear Information System (INIS)

    Borsten, L.; Dahanayake, D.; Duff, M.J.; Ebrahim, H.; Rubens, W.

    2009-01-01

    We review the recently established relationships between black hole entropy in string theory and the quantum entanglement of qubits and qutrits in quantum information theory. The first example is provided by the measure of the tripartite entanglement of three qubits (Alice, Bob and Charlie), known as the 3-tangle, and the entropy of the 8-charge STU black hole of N=2 supergravity, both of which are given by the [SL(2)] 3 invariant hyperdeterminant, a quantity first introduced by Cayley in 1845. Moreover the classification of three-qubit entanglements is related to the classification of N=2 supersymmetric STU black holes. There are further relationships between the attractor mechanism and local distillation protocols and between supersymmetry and the suppression of bit flip errors. At the microscopic level, the black holes are described by intersecting D3-branes whose wrapping around the six compact dimensions T 6 provides the string-theoretic interpretation of the charges and we associate the three-qubit basis vectors, |ABC>(A,B,C=0 or 1), with the corresponding 8 wrapping cycles. The black hole/qubit correspondence extends to the 56 charge N=8 black holes and the tripartite entanglement of seven qubits where the measure is provided by Cartan's E 7 contains [SL(2)] 7 invariant. The qubits are naturally described by the seven vertices ABCDEFG of the Fano plane, which provides the multiplication table of the seven imaginary octonions, reflecting the fact that E 7 has a natural structure of an O-graded algebra. This in turn provides a novel imaginary octonionic interpretation of the 56=7x8 charges of N=8: the 24=3x8 NS-NS charges correspond to the three imaginary quaternions and the 32=4x8 R-R to the four complementary imaginary octonions. We contrast this approach with that based on Jordan algebras and the Freudenthal triple system. N=8 black holes (or black strings) in five dimensions are also related to the bipartite entanglement of three qutrits (3-state systems

  15. Cosmology with primordial black holes

    International Nuclear Information System (INIS)

    Lindley, D.

    1981-09-01

    Cosmologies containing a substantial amount of matter in the form of evaporating primordial black holes are investigated. A review of constraints on the numbers of such black holes, including an analysis of a new limit found by looking at the destruction of deuterium by high energy photons, shows that there must be a negligible population of small black holes from the era of cosmological nucleosynthesis onwards, but that there are no strong constraints before this time. The major part of the work is based on the construction of detailed, self-consistent cosmological models in which black holes are continually forming and evaporating The interest in these models centres on the question of baryon generation, which occurs via the asymmetric decay of a new type of particle which appears as a consequence of the recently developed Grand Unified Theories of elementary particles. Unfortunately, there is so much uncertainty in the models that firm conclusions are difficult to reach; however, it seems feasible in principle that primordial black holes could be responsible for a significant part of the present matter density of the Universe. (author)

  16. Black holes: a slanted overview

    International Nuclear Information System (INIS)

    Vishveshwara, C.V.

    1988-01-01

    The black hole saga spanning some seventy years may be broadly divided into four phases, namely, (a) the dark ages when little was known about black holes even though they had come into existence quite early through the Schwarzschild solution, (b) the age of enlightenment bringing in deep and prolific discoveries, (c) the age of fantasy that cast black holes in all sorts of extraordinary roles, and (d) the golden age of relativistic astrophysics - to some extent similar to Dirac's characterisation of the development of quantum theory - in which black holes have been extensively used to elucidate a number of astrophysical phenomena. It is impossible to give here even the briefest outline of the major developments in this vast area. We shall only attempt to present a few aspects of black hole physics which have been actively pursued in the recent past. Some details are given in the case of those topics that have not found their way into text books or review articles. (author)

  17. Theory and simulations of electron vortices generated by magnetic pushing

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, A. S.; Angus, J. R.; Swanekamp, S. B.; Schumer, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Ottinger, P. F. [An Independent Consultant through ENGILITY, Chantilly, Virginia 20151 (United States)

    2013-08-15

    Vortex formation and propagation are observed in kinetic particle-in-cell (PIC) simulations of magnetic pushing in the plasma opening switch. These vortices are studied here within the electron-magnetohydrodynamic (EMHD) approximation using detailed analytical modeling. PIC simulations of these vortices have also been performed. Strong v×B forces in the vortices give rise to significant charge separation, which necessitates the use of the EMHD approximation in which ions are fixed and the electrons are treated as a fluid. A semi-analytic model of the vortex structure is derived, and then used as an initial condition for PIC simulations. Density-gradient-dependent vortex propagation is then examined using a series of PIC simulations. It is found that the vortex propagation speed is proportional to the Hall speed v{sub Hall}≡cB{sub 0}/4πn{sub e}eL{sub n}. When ions are allowed to move, PIC simulations show that the electric field in the vortex can accelerate plasma ions, which leads to dissipation of the vortex. This electric field contributes to the separation of ion species that has been observed to occur in pulsed-power experiments with a plasma-opening switch.

  18. CERN's surveyors are pushing back the frontiers of precision

    CERN Multimedia

    2001-01-01

    Aiming at a target on the other side of the Alps, 730 kilometres from CERN, or controlling the positions of thousands of devices to a precision of one tenth of a millimetre, these are just some of the painstaking tasks undertaken by the surveyors in the Positioning Metrology and Surveying Group. These masters of measurement are pushing precision to its very limit.Go down into the LEP tunnel, walk about half a mile and then try to imagine how you could possibly take precise aim at something hundreds of kilometres away without any reference to the surface. Absurd, you might think? Not entirely, for that, in a nutshell, is the geodetic challenge of the Gran Sasso project. Indeed it is just one of the challenges faced by the surveyors in CERN's Positioning Metrology and Surveying Group, whose task it will be to aim a neutrino beam at a detector located in an underground cavern 732 kilometres away at INFN's Gran Sasso laboratory in Italy. The tools for solving such problems are provided by geodetics, the branch of...

  19. On push-forward representations in the standard gyrokinetic model

    International Nuclear Information System (INIS)

    Miyato, N.; Yagi, M.; Scott, B. D.

    2015-01-01

    Two representations of fluid moments in terms of a gyro-center distribution function and gyro-center coordinates, which are called push-forward representations, are compared in the standard electrostatic gyrokinetic model. In the representation conventionally used to derive the gyrokinetic Poisson equation, the pull-back transformation of the gyro-center distribution function contains effects of the gyro-center transformation and therefore electrostatic potential fluctuations, which is described by the Poisson brackets between the distribution function and scalar functions generating the gyro-center transformation. Usually, only the lowest order solution of the generating function at first order is considered to explicitly derive the gyrokinetic Poisson equation. This is true in explicitly deriving representations of scalar fluid moments with polarization terms. One also recovers the particle diamagnetic flux at this order because it is associated with the guiding-center transformation. However, higher-order solutions are needed to derive finite Larmor radius terms of particle flux including the polarization drift flux from the conventional representation. On the other hand, the lowest order solution is sufficient for the other representation, in which the gyro-center transformation part is combined with the guiding-center one and the pull-back transformation of the distribution function does not appear

  20. On push-forward representations in the standard gyrokinetic model

    Energy Technology Data Exchange (ETDEWEB)

    Miyato, N., E-mail: miyato.naoaki@jaea.go.jp; Yagi, M. [Japan Atomic Energy Agency, 2-116 Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan); Scott, B. D. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-01-15

    Two representations of fluid moments in terms of a gyro-center distribution function and gyro-center coordinates, which are called push-forward representations, are compared in the standard electrostatic gyrokinetic model. In the representation conventionally used to derive the gyrokinetic Poisson equation, the pull-back transformation of the gyro-center distribution function contains effects of the gyro-center transformation and therefore electrostatic potential fluctuations, which is described by the Poisson brackets between the distribution function and scalar functions generating the gyro-center transformation. Usually, only the lowest order solution of the generating function at first order is considered to explicitly derive the gyrokinetic Poisson equation. This is true in explicitly deriving representations of scalar fluid moments with polarization terms. One also recovers the particle diamagnetic flux at this order because it is associated with the guiding-center transformation. However, higher-order solutions are needed to derive finite Larmor radius terms of particle flux including the polarization drift flux from the conventional representation. On the other hand, the lowest order solution is sufficient for the other representation, in which the gyro-center transformation part is combined with the guiding-center one and the pull-back transformation of the distribution function does not appear.