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Black hole

Yan Li, Chengjie Zhu, W R Garrett, E W Hagley, L Deng
The realization of atomic quantum gases has brought out surprising effects that have no correspondence in nonlinear optics with thermal gases, presenting intriguing and exciting challenges to the research discipline of nonlinear optics which has matured since the invention of the laser. Here, we show an unexpected optical wave-mixing gain cancellation effect in a quantum gas that restricts an, otherwise, strongly enhanced backward-propagating light-matter wave-mixing process. This results in a wave-mixing induced transparency and a nonhyperbolic quasi-matter-wave soliton that opens new research opportunities in hydrodynamic fluid research of degenerate quantum gases, such as phonon scattering in a two-dimensional sonic black hole horizon...
January 6, 2017: Physical Review Letters
Maarten van de Meent
The linear in mass ratio correction to the periapsis advance of equatorial nearly circular orbits around a spinning black hole is calculated for the first time and to a very high precision, providing a key benchmark for different approaches modeling spinning binaries. The high precision of the calculation is leveraged to discriminate between two recent incompatible derivations of the 4 post-Newtonian equations of motion. Finally, the limit of the periapsis advance near the innermost stable orbit (ISCO) allows the determination of the ISCO shift, validating previous calculations using the first law of binary mechanics...
January 6, 2017: Physical Review Letters
C Thaler, T D Faizy, J Sedlacik, B Holst, K Stürner, C Heesen, J-P Stellmann, J Fiehler, S Siemonsen
BACKGROUND AND PURPOSE: Quantitative MR imaging parameters help to evaluate disease progression in multiple sclerosis and increase correlation with clinical disability. We therefore hypothesized that T1 values might be a marker for ongoing tissue damage or even remyelination and may help increase clinical correlation. MATERIALS AND METHODS: MR imaging was performed in 17 patients with relapsing-remitting MS at baseline and after 12 months of starting immunotherapy with dimethyl fumarate...
November 10, 2016: AJNR. American Journal of Neuroradiology
Athanassios G Kontos, Andreas Kaltzoglou, Eirini Siranidi, Dimitrios Palles, Giasemi K Angeli, Michalis K Arfanis, Vassilis Psycharis, Yannis S Raptis, Efstratios I Kamitsos, Pantelis N Trikalitis, Constantinos C Stoumpos, Mercouri G Kanatzidis, Polycarpos Falaras
The CsSnI3 perovskite and the corresponding SnF2-containing material with nominal composition CsSnI2.95F0.05 were synthesized by solid-state reactions and structurally characterized by powder X-ray diffraction. Both materials undergo rapid phase transformation upon exposure to air from the black orthorhombic phase (B-γ-CsSnI3) to the yellow orthorhombic phase (Y-CsSnI3), followed by irreversible oxidation into Cs2SnI6 within several hours. The phase transition occurs at a significantly lower rate in the SnF2-containing material rather than in the pure perovskite...
January 3, 2017: Inorganic Chemistry
Wolfgang Tichy
Spacetime is foliated by spatial hypersurfaces in the 3+1 split of general relativity. The initial value problem then consists of specifying initial data for all fields on one such a spatial hypersurface, such that the subsequent evolution forward in time is fully determined. On each hypersurface the 3-metric and extrinsic curvature describe the geometry. Together with matter fields such as fluid velocity, energy density and rest mass density, the 3-metric and extrinsic curvature then constitute the initial data...
December 23, 2016: Reports on Progress in Physics
Adam Levi, Amos Ori
We report here on a new method for calculating the renormalized stress-energy tensor (RSET) in black-hole (BH) spacetimes, which should also be applicable to dynamical BHs and to spinning BHs. This new method only requires the spacetime to admit a single symmetry. Thus far, we have developed three variants of the method, aimed for stationary, spherically symmetric, or axially symmetric BHs. We used this method to calculate the RSET of a minimally coupled massless scalar field in Schwarzschild and Reissner-Nordström backgrounds for several quantum states...
December 2, 2016: Physical Review Letters
Matthew W Kunz, James M Stone, Eliot Quataert
We present results from the first 3D kinetic numerical simulation of magnetorotational turbulence and dynamo, using the local shearing-box model of a collisionless accretion disk. The kinetic magnetorotational instability grows from a subthermal magnetic field having zero net flux over the computational domain to generate self-sustained turbulence and outward angular-momentum transport. Significant Maxwell and Reynolds stresses are accompanied by comparable viscous stresses produced by field-aligned ion pressure anisotropy, which is regulated primarily by the mirror and ion-cyclotron instabilities through particle trapping and pitch-angle scattering...
December 2, 2016: Physical Review Letters
Gen Long, Denis Maryenko, Junying Shen, Shuigang Xu, Jianqiang Hou, Zefei Wu, Wing Ki Wong, Tianyi Han, Jiangxiazi Lin, Yuan Cai, Rolf Lortz, Ning Wang
We demonstrate that a field-effect transistor (FET) made of few-layer black phosphorus (BP) encapsulated in hexagonal boron nitride (h-BN) in vacuum exhibits a room-temperature hole mobility of 5200 cm(2)/(Vs), being limited just by the phonon scattering. At cryogenic temperatures, the FET mobility increases up to 45 000 cm(2)/(Vs), which is five times higher compared to the mobility obtained in earlier reports. The unprecedentedly clean h-BN-BP-h-BN heterostructure exhibits Shubnikov-de Haas oscillations and a quantum Hall effect with Landau level (LL) filling factors down to v = 2 in conventional laboratory magnetic fields...
December 14, 2016: Nano Letters
Markus A Huber, Fabian Mooshammer, Markus Plankl, Leonardo Viti, Fabian Sandner, Lukas Z Kastner, Tobias Frank, Jaroslav Fabian, Miriam S Vitiello, Tyler L Cocker, Rupert Huber
The possibility of hybridizing collective electronic motion with mid-infrared light to form surface polaritons has made van der Waals layered materials a versatile platform for extreme light confinement and tailored nanophotonics. Graphene and its heterostructures have attracted particular attention because the absence of an energy gap allows plasmon polaritons to be tuned continuously. Here, we introduce black phosphorus as a promising new material in surface polaritonics that features key advantages for ultrafast switching...
December 12, 2016: Nature Nanotechnology
Carlos A R Herdeiro, Eugen Radu
We explicitly construct static black hole solutions to the fully nonlinear, D=4, Einstein-Maxwell-anti-de Sitter (AdS) equations that have no continuous spatial symmetries. These black holes have a smooth, topologically spherical horizon (section), but without isometries, and approach, asymptotically, global AdS spacetime. They are interpreted as bound states of a horizon with the Einstein-Maxwell-AdS solitons recently discovered, for appropriate boundary data. In sharp contrast to the uniqueness results for a Minkowski electrovacuum, the existence of these black holes shows that single, equilibrium, black hole solutions in an AdS electrovacuum admit an arbitrary multipole structure...
November 25, 2016: Physical Review Letters
Vasilios K Kimiskidis, Vasileios Papaliagkas, Kyriaki Sotirakoglou, Zoi K Kouvatsou, Victoria K Kapina, Efrosini Papadaki, Vaia Tsimourtou, Elvira Masoura, Dimitrios A Kazis, Sotirios Papayiannopoulos, Triantafyllos Geroukis, Sevasti Bostanjopoulou
BACKGROUND: Cognitive event-related potentials (ERPs) have been previously correlated with T2 lesion load (Τ2LL) in patients with multiple sclerosis (MS). It is currently unknown, however, whether ERPs also correlate with brain atrophy or the presence of T1 hypointense lesions ("black holes") which reflect tissue destruction and axonal loss. The primary aim of the current study is to explore the effect of neuroradiological parameters such as brain atrophy, T1 and T2 lesion load on auditory ERPs in MS patients...
November 2016: Multiple Sclerosis and related Disorders
Juan Maldacena
No abstract text is available yet for this article.
October 18, 2016: Scientific American
Micah R Shepherd, Philip A Feurtado, Stephen C Conlon
Structures with power law tapers exhibit the acoustic black hole (ABH) effect and can be used for vibration reduction. However, the design of ABHs for vibration reduction requires consideration of the underlying theory and its regions of validity. To address the competing nature of the best ABH design for vibration reduction and the underlying theoretical assumptions, a multi-objective approach is used to find the lowest frequency where both criteria are sufficiently met. The Pareto optimality curve is estimated for a range of ABH design parameters...
September 2016: Journal of the Acoustical Society of America
Mehrdad Mirbabayi, Massimo Porrati
A recent, intriguing Letter by Hawking, Perry, and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole information paradox. In this Letter we make use of factorization theorems for infrared divergences of the S matrix to argue that by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S matrix becomes essentially trivial. The information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta...
November 18, 2016: Physical Review Letters
S Karki, D Tuyenbayev, S Kandhasamy, B P Abbott, T D Abbott, E H Anders, J Berliner, J Betzwieser, C Cahillane, L Canete, C Conley, H P Daveloza, N De Lillo, J R Gleason, E Goetz, K Izumi, J S Kissel, G Mendell, V Quetschke, M Rodruck, S Sachdev, T Sadecki, P B Schwinberg, A Sottile, M Wade, A J Weinstein, M West, R L Savage
The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators...
November 2016: Review of Scientific Instruments
Iosif Bena, Stefano Giusto, Emil J Martinec, Rodolfo Russo, Masaki Shigemori, David Turton, Nicholas P Warner
We construct the first family of horizonless supergravity solutions that have the same mass, charges, and angular momenta as general supersymmetric rotating D1-D5-P black holes in five dimensions. This family includes solutions with arbitrarily small angular momenta, deep within the regime of quantum numbers and couplings for which a large classical black hole exists. These geometries are well approximated by the black-hole solution, and in particular exhibit the same near-horizon throat. Deep in this throat, the black-hole singularity is resolved into a smooth cap...
November 11, 2016: Physical Review Letters
Vuk Mandic, Simeon Bird, Ilias Cholis
Recent Advanced LIGO detections of binary black hole mergers have prompted multiple studies investigating the possibility that the heavy GW150914 binary system was of primordial origin, and hence could be evidence for dark matter in the form of black holes. We compute the stochastic background arising from the incoherent superposition of such primordial binary black hole systems in the Universe and compare it to the similar background spectrum due to binary black hole systems of stellar origin. We investigate the possibility of detecting this background with future gravitational-wave detectors, and conclude that constraining the dark matter component in the form of black holes using stochastic gravitational-wave background measurements will be very challenging...
November 11, 2016: Physical Review Letters
Ji Yeon Hwang, Sang Tae Kim, Ho-Seong Han, Kyunggon Kim, Jin Soo Han
Fluorescence detecting of exogenous EpCAM (epithelial cell adhesion molecule) or muc1 (mucin1) expression correlated to cancer metastasis using nanoparticles provides pivotal information on CTC (circulating tumor cell) occurrence in a noninvasive tool. In this study, we study a new skill to detect extracellular EpCAM/muc1 using quantum dot-based aptamer beacon (QD-EpCAM/muc1 ALB (aptamer linker beacon). The QD-EpCAM/muc1 ALB was designed using QDs (quantum dots) and probe. The EpCAM/muc1-targeting aptamer contains a Ep-CAM/muc1 binding sequence and BHQ1 (black hole quencher 1) or BHQ2 (black hole quencher2)...
November 23, 2016: Sensors
Stephanie LaMassa
No abstract text is available yet for this article.
December 1, 2016: Nature
Aaron Zimmerman, Adam G M Lewis, Harald P Pfeiffer
The redshift factor z is an invariant quantity of fundamental interest in post-Newtonian and self-force descriptions of compact binaries. It connects different approximation schemes, and plays a central role in the first law of binary black hole mechanics, which links local quantities to asymptotic measures of energy and angular momentum in these systems. Through this law, the redshift factor is conjectured to have a close relation to the surface gravity of the event horizons of black holes in circular orbits...
November 4, 2016: Physical Review Letters
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