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Black hole

Karl Landsteiner, Esperanza Lopez, Guillermo Milans Del Bosch
In the presence of a gravitational contribution to the chiral anomaly, the chiral magnetic effect induces an energy current proportional to the square of the temperature in equilibrium. In holography the thermal state corresponds to a black hole. We numerically study holographic quenches in which a planar shell of scalar matter falls into a black hole and raises its temperature. During the process the momentum density (energy current) is conserved. The energy current has two components, a nondissipative one induced by the anomaly and a dissipative flow component...
February 16, 2018: Physical Review Letters
Jonathan C Ryan, Alun Hubbard, Marek Stibal, Tristram D Irvine-Fynn, Joseph Cook, Laurence C Smith, Karen Cameron, Jason Box
Albedo-a primary control on surface melt-varies considerably across the Greenland Ice Sheet yet the specific surface types that comprise its dark zone remain unquantified. Here we use UAV imagery to attribute seven distinct surface types to observed albedo along a 25 km transect dissecting the western, ablating sector of the ice sheet. Our results demonstrate that distributed surface impurities-an admixture of dust, black carbon and pigmented algae-explain 73% of the observed spatial variability in albedo and are responsible for the dark zone itself...
March 14, 2018: Nature Communications
Sherif M Hamdy, Maged Abdel-Naseer, Nevin M Shalaby, Alaa Elmazny, Marian Girgis, Mona A Nada, Amr Hassan, Husam S Mourad, Mohamed I Hegazy, Ahmed Abdelalim, Nirmeen A Kishk, Noha T Abokrysha, Shaimaa A Genedy, Ehab A Essawy, Hatem S Shehata
Introduction: Although the frequency of pediatric-onset multiple sclerosis (POMS) has increased in recent decades, it is still highly uncommon, which creates a need for the involvement of more registries from various clinical centers. Objective: To characterize the demographic, clinical, and paraclinical features of Egyptian patients with POMS. Patients and methods: A retrospective chart review study was undertaken on 237 Egyptian patients with demyelinating events which started before the age of 18 years who attended one of five tertiary referral centers in Cairo, Egypt...
2018: Neuropsychiatric Disease and Treatment
Stephen C Conlon, Philip A Feurtado
Acoustic black holes (ABHs) have been explored and demonstrated to be effective passive treatments for broadband noise and vibration control. Performance metrics for assessing damping concepts are often focused on maximizing structural damping loss factors. Optimally performing damping treatments can reduce the resonant response of a driven system well below the direct field response. This results in a finite structure whose vibration input-output response follows that of an infinite structure. The vibration mobility transfer functions between locations on a structure can be used to assess the structure's vibration response phase, and compare its phase response characteristics to those of idealized systems...
February 2018: Journal of the Acoustical Society of America
Shan-Shan Li, Qing-Ying Kong, Miao Zhang, Fan Yang, Bin Kang, Jing-Juan Xu, Hong-Yuan Chen
The small absorption cross sections of most molecules led to the low sensitivity of traditional optical absorption spectroscopy. This obstacle might be overcome by applying the near-field plasmon resonance energy transfer (PRET) between plasmonic nanoparticle and surrounding molecules. In this work, we utilized PRET-based spectroscopy on single gold nanostars to study the specific biomolecule recognition and enzyme kinetics choosing biotin-SA pair and DNase I as models. By analyzing the changes of absorption spectra for black hole quencher 3 (BHQ3), derived from spectra difference, we explored the kinetics of specific biomolecule recognition and enzyme digestion in different physiological environment, and we found that the viscosities of media and the sizes of molecules play vital role in biomolecular recognition and enzyme digestion...
March 6, 2018: Analytical Chemistry
Tatsuo Azeyanagi, Frank Ferrari, Fidel I Schaposnik Massolo
We study the Schwinger-Dyson equations of a fermionic planar matrix quantum mechanics [or tensor and Sachdev-Ye-Kitaev (SYK) models] at leading melonic order. We find two solutions describing a high entropy, SYK black-hole-like phase and a low entropy one with trivial IR behavior. There is a line of first order phase transitions that terminates at a new critical point. Critical exponents are nonmean field and differ on the two sides of the transition. Interesting phenomena are also found in unstable and stable bosonic models, including Kazakov critical points and inconsistency of SYK-like solutions of the IR limit...
February 9, 2018: Physical Review Letters
Zheng Cao, Sourabh Nampalliwar, Cosimo Bambi, Thomas Dauser, Javier A García
Recently, we have extended the x-ray reflection model relxill to test the spacetime metric in the strong gravitational field of astrophysical black holes. In the present Letter, we employ this extended model to analyze XMM-Newton, NuSTAR, and Swift data of the supermassive black hole in 1H0707-495 and test deviations from a Kerr metric parametrized by the Johannsen deformation parameter α_{13}. Our results are consistent with the hypothesis that the spacetime metric around the black hole in 1H0707-495 is described by the Kerr solution...
February 2, 2018: Physical Review Letters
Adriana Unic, Nora Nikolac Gabaj, Marijana Miler, Jelena Culej, Adrijana Lisac, Anita Horvat, Nada Vrkic
BACKGROUND: Study was performed in order: (i) to assess the comparability of glucose, bilirubin, hemoglobin, leukocyte esterase, and protein; (ii) to assess accuracy of glucose, bilirubin, hemoglobin, leukocyte esterase, and protein; and (iii) to evaluate interference of ascorbic acid on the glucose, bilirubin, hemoglobin, and nitrite determination using 2 different dipsticks: iChem Velocity, Iris Diagnostics and Combur-10M, Roche Diagnostics. METHODS: Random urine specimens were included in the study...
February 25, 2018: Journal of Clinical Laboratory Analysis
Shanna L Bowman, Michael S Marks
The mechanisms by which melanins are transferred from melanocytes and stored within keratinocytes to generate skin pigmentation are hotly debated. Correia et al. and Hurbain et al. provide evidence that melanin cores of melanosomes are secreted from melanocytes and taken up and stored within non-degradative membranous organelles in keratinocytes in the basal epidermis of human skin.
March 2018: Journal of Investigative Dermatology
Sheng Yang, Ke Zhang, Antonio Gaetano Ricciardulli, Panpan Zhang, Zhongquan Liao, Martin Lohe, Ehrenfried Zschech, Paul Blom, Wojciech Pisula, Klaus Müllen, Xinliang Feng
The extraordinary electronic and photonic features render black phosphorus (BP) an important material for the development of novel electronics and optoelectronics. Despite the recent progress in the preparation of few-layered BP flakes, scalable synthesis of large-size, pristine BP flakes represents one of the main challenges. Here we demonstrate an electrochemical delamination strategy, based on the intercalation of diverse cations in non-aqueous electrolytes, to peel off bulk BP crystals into few-layer, defect-free flakes...
February 23, 2018: Angewandte Chemie
Mark M Hammer, Rachna Madan, Hiroto Hatabu
OBJECTIVE: Pulmonary mucormycosis is an aggressive opportunistic fungal infection. We set out to evaluate the CT and MRI features of pulmonary mucormycosis. MATERIALS AND METHODS: Through a search of the electronic medical record from 2007 to 2017, we identified 30 patients with definite or probable mucormycosis. Two radiologists reviewed the initial chest CT examinations for the presence of features including the "reverse halo" sign, large ground-glass halo, and peripheral lesion distribution...
February 22, 2018: AJR. American Journal of Roentgenology
Yizhang Liu, Xuekai Jiang, Wenfeng Cao, Junyong Sun, Feng Gao
Carboxyl-functionalized semiconducting polymer dots (Pdots) were synthesized as an energy donor by the nanoprecipitation method. A black hole quenching dye (BHQ-labelled thrombin aptamers) was used as the energy acceptor, and fluorescence resonance energy transfer between the aptamers and Pdots was used for fluorescence quenching of the Pdots. The addition of thrombin restored the fluorescence intensity. Under the optimized experimental conditions, the fluorescence of the system was restored to the maximum when the concentration of thrombin reached 130 nM, with a linear range of 0-50 nM (R² = 0...
February 14, 2018: Sensors
Xuhui Wei, Shitan Wang, Can Wang, Menglong Zhu, Yuan Zhao, Haipeng Xie, Dongmei Niu, Yongli Gao
The interfacial electronic structure and morphology of nanofilm of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on black phosphorus (BP) was investigated with photoemission spectroscopy (PES) and atomic force microscopy (AFM). The heterojunction of C8-BTBT/BP is a straddling one with a hole injection barrier of 1.41 eV and electron injection barrier of 2.43 eV from BP to C8-BTBT. There is a 0.18 eV interface dipole pointing from BP to C8-BTBT, which means a relative weak interaction of substrate BP and the C8-BTBT molecules...
June 1, 2018: Journal of Nanoscience and Nanotechnology
X J Li, Jiahan Yu, Kun Luo, Zhenhua Wu, Wen Yang
We investigate theoretically the effects of modulated periodic perpendicular magnetic fields on the electronic states and optical absorption spectrum in a monolayer black phosphorus (phosphorene). We demonstrate that different phosphorene magnetic superlattice (PMS) orientations can give rise to distinct energy spectra, i.e., tuning the intrinsic electronic anisotropy. The Rashba spin-orbit coupling (RSOC) will develop a spin-splitting energy dispersion in this phosphorene magnetic superlattice...
February 13, 2018: Nanotechnology
S Das, T Sahoo, M H Meylan
The propagation of flexural gravity waves, routinely used to model wave interaction with sea ice, is studied, including the effect of compression and current. A number of significant and surprising properties are shown to exist. The occurrence of blocking above a critical value of compression is illustrated. This is analogous to propagation of surface gravity waves in the presence of opposing current and light wave propagation in the curved space-time near a black hole, therefore providing a novel system for studying analogue gravity...
January 2018: Proceedings. Mathematical, Physical, and Engineering Sciences
Hannah Middleton, Siyuan Chen, Walter Del Pozzo, Alberto Sesana, Alberto Vecchio
Pulsar timing arrays are presently the only means to search for the gravitational wave stochastic background from super massive black hole binary populations, considered to be within the grasp of current or near-future observations. The stringent upper limit from the Parkes Pulsar Timing Array has been interpreted as excluding (>90% confidence) the current paradigm of binary assembly through galaxy mergers and hardening via stellar interaction, suggesting evolution is accelerated or stalled. Using Bayesian hierarchical modelling we consider implications of this upper limit for a range of astrophysical scenarios, without invoking stalling, nor more exotic physical processes...
February 8, 2018: Nature Communications
Qi Li, Wen-Song Yang, Sheng-Li Chen, Fu-Rong Lv, Fa-Jin Lv, Xi Hu, Dan Zhu, Du Cao, Xing-Chen Wang, Rui Li, Liang Yuan, Xin-Yue Qin, Peng Xie
BACKGROUND: In spontaneous intracerebral hemorrhage (ICH), black hole sign has been proposed as a promising imaging marker that predicts hematoma expansion in patients with ICH. The aim of our study was to investigate whether admission CT black hole sign predicts hematoma growth in patients with ICH. METHODS: From July 2011 till February 2016, patients with spontaneous ICH who underwent baseline CT scan within 6 h of symptoms onset and follow-up CT scan were recruited into the study...
January 10, 2018: Cerebrovascular Diseases
Vitor Cardoso, João L Costa, Kyriakos Destounis, Peter Hintz, Aron Jansen
The fate of Cauchy horizons, such as those found inside charged black holes, is intrinsically connected to the decay of small perturbations exterior to the event horizon. As such, the validity of the strong cosmic censorship (SCC) conjecture is tied to how effectively the exterior damps fluctuations. Here, we study massless scalar fields in the exterior of Reissner-Nordström-de Sitter black holes. Their decay rates are governed by quasinormal modes of the black hole. We identify three families of modes in these spacetimes: one directly linked to the photon sphere, well described by standard WKB-type tools; another family whose existence and time scale is closely related to the de Sitter horizon; finally, a third family which dominates for near-extremally charged black holes and which is also present in asymptotically flat spacetimes...
January 19, 2018: Physical Review Letters
Che-Yu Chen, Mariam Bouhmadi-López, Pisin Chen
The vacuum, static, and spherically symmetric solutions in the mimetic Born-Infeld gravity are studied. The mimetic Born-Infeld gravity is a reformulation of the Eddington-inspired-Born-Infeld (EiBI) model under the mimetic approach. Due to the mimetic field, the theory contains non-trivial vacuum solutions different from those in Einstein gravity. We find that with the existence of the mimetic field, the spacelike singularity inside a Schwarzschild black hole could be altered to a lightlike singularity, even though the curvature invariants still diverge at the singularity...
2018: European Physical Journal. C, Particles and Fields
Sumandeep Kaur, Ashok Kumar, Sunita Srivastava, Ravi Pandey, Tankeshwar Kumar
A few-layer black phosphorene has recently gained significant interest in the scientific community. In this paper, we consider several polymorphs of phosphorene nanoribbons (PNRs) and employ deformation potential theory within the effective mass approximation together with density functional theory to investigate their structural, mechanical and electronic properties. The results show that stability of PNRs strongly depends on the direction along which they can be cut from 2D counterpart. PNRs also exhibit a wide range of line stiffness ranging from 6×10<sup>10</sup> eV/m to 18 × 10<sup>11</sup> eV/m which has little dependence on the edge passivation...
February 1, 2018: Nanotechnology
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