A Liquid Model Analogue for Black Hole Thermodynamics
Hochberg, D; Hochberg, David; Pérez-Mercader, Juan
1996-01-01
We are able to characterize a 2--dimensional classical fluid sharing some of the same thermodynamic state functions as the Schwarzschild black hole. This phenomenological correspondence between black holes and fluids is established by means of the model liquid's pair-correlation function and the two-body atomic interaction potential. These latter two functions are calculated exactly in terms of the black hole internal (quasilocal) energy and the isothermal compressibility. We find the existence of a ``screening" like effect for the components of the liquid.
Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation
Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn
2016-03-01
Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors.
Large-Scale, Highly Efficient, and Green Liquid-Exfoliation of Black Phosphorus in Ionic Liquids.
Zhao, Wancheng; Xue, Zhimin; Wang, Jinfang; Jiang, Jingyun; Zhao, Xinhui; Mu, Tiancheng
2015-12-23
We developed a facile, large-scale, and environmentally friendly liquid-exfoliation method to produce stable and high-concentration dispersions of mono- to few-layer black phosphorus (BP) nanosheets from bulk BP using nine ionic liquids. The prepared suspensions can stabilize without any obvious sedimentation and aggregation in ambient air for one month. In particular, the concentration (up to 0.95 mg mL(-1)) of BP nanoflakes obtained in 1-hydroxyethyl-3-methylimidazolium trifluoromethansulfonate ([HOEMIM][TfO]) is the highest reported for BP nanosheets dispersions. This work provides new opportunities for preparing atomically thin BP nanosheets in green, large-scale, and highly concentrated processes and achieving its in situ application. PMID:26642883
THE LIGNIN CONTENT IN BLACK LIQUID OF STRAW AS-AQ BY ULTRAVIOLET SPECTROPHOTOMETER
Institute of Scientific and Technical Information of China (English)
HaiqiangShi; BingyueLiu; XingqiangLi; LongquanXu; BeihaiHe
2004-01-01
The measurement of lignin content in black liquid of straw AS-AQ by ultraviolet spectrophotometer (UV) is discussed in this paper. Different dilution multiple and contrast solutions have an effect on the measured results of the lignin content by UV. The calculation method for the absorption coefficient and thes canning spectrum property of liquor acidified by SO are introduced in this paper.
Gradient induced liquid motion on laser structured black Si surfaces
Paradisanos, I; Anastasiadis, S H; Stratakis, E
2015-01-01
This letter reports on the femtosecond laser fabrication of gradient-wettability micro/nano- patterns on Si surfaces. The dynamics of directional droplet spreading on the surface tension gradients developed is systematically investigated and discussed. It is shown that microdroplets on the patterned surfaces spread at a maximum speed of 505 mm/sec, that is the highest velocity demonstrated so far for liquid spreading on a surface tension gradient in ambient conditions. The application of the proposed laser patterning technique for the precise fabrication of surface tension gradients for open microfluidic systems, liquid management in fuel cells and drug delivery is envisaged.
Applying tracer techniques to NPP Cernavoda liquid effluents dispersed in Danube - Black Sea Canal
International Nuclear Information System (INIS)
Full text: In this study we propose to use tritiated liquid effluents from CANDU type Cernavoda NPP as a tracer, to study dispersion efficiency on Danube-Black Sea Canal. Tritiated water can be used to simulate the transport and dispersion of solutes in Danube-Black Sea Canal because they have the same physical characteristics as water. A study of experimental published formulas was used to determine proper mixing length. Simultaneous measurements in different locations of the Canal confirm the inlet location of the experiment. Another result used in the further experiment concerns the tritium level along the Danube-Black Sea Canal. We measured tritium activity concentration in water sampled along the Canal between July 2002-April 2003. We established tritium level and tritium concentrations significant for the edge and the tail of tritiated wastewater releases. We obtained unit-peak-attenuation (UPA) curve as related to different mixing times using three locations in which we measured tracer-response curves. During the releases of tritiated liquid effluents we determined the slope of the UPA curve, that helped us to model the water movement in observed area of Danube-Black Sea Canal. In this way with a specific software we can predict maximum concentration of soluble pollutant accidental spills in studied area. (authors)
THE LIGNIN CONTENT IN BLACK LIQUID OF STRAW AS-AQ BY ULTRAVIOLET SPECTROPHOTOMETER
Institute of Scientific and Technical Information of China (English)
Haiqiang Shi; Bingyue Liu; Xingqiang Li; Longquan Xu; Beihai He
2004-01-01
The measurement of lignin content in black liquid of straw AS-AQ by ultraviolet spectrophotometer (UV)is discussed in this paper. Different dilution multiple and contrast solutions have an effect on the measured results of the lignin content by UV. The calculation method for the absorption coefficient and the scanning spectrum property of liquor acidified by SO2 are introduced in this paper.
Electrodeposition of black chromium thin films from trivalent chromium-ionic liquid solution
Eugénio, S.; Vilar, Rui; C. M. Rangel; Baskaran, I.
2009-01-01
In the present study, black chromium thin films were electrodeposited from a solution of 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIm][BF4] ionic liquid containing trivalent chromium (Cr(III)). Homogeneous and well adherent coatings have been obtained on nickel, copper and stainless steel substrates. The nucleation and growth of the films were investigated by cyclic voltammetry and current-density/time transient techniques. SEM/EDS, XPS and XRD were used to study the morphology, chem...
Electrodeposition of black chromium from CR(III) ionic liquid solution
Eugénio, S.; Rangel, C. M.; Vilar, Rui
2009-01-01
Black chromium is an important coating material used in solar thermal systems as a spectrally selective surface. This coating is usually obtained by electrodeposition from sulphate free chromium (VI) aqueous solutions which represent a health and environmental hazard due to the presence of Cr(VI), a known toxic and carcinogenic agent. Recent developments in green chemistry have shown that ionic liquids can be used as electrolytes, allowing the deposition of a wide range of materials with negl...
Discrimination of Black Ball-point Pen Inks by High Performance Liquid Chromatography (HPLC)
International Nuclear Information System (INIS)
In this study, thirteen types of black ball-point pen inks of three major brands were analyzed using high performance liquid chromatography (HPLC). Separation of the ink components was achieved using Bondapak C-18 column with gradient elution using water, ethanol and ethyl acetate. The chromatographic data obtained at wavelength 254.8 nm was analyzed using agglomerative hierarchical clustering (AHC) and principle component analysis (PCA). AHC was able to group the inks into three clusters. This result was supported by PCA, whereby distinct separation of the three different brands was achieved. Therefore, HPLC in combination with chemometric methods may be a valuable tool for the analysis of black ball-point pen inks for forensic purposes. (author)
Hanlon, Damien; Backes, Claudia; Doherty, Evie; Cucinotta, Clotilde S.; Berner, Nina C.; Boland, Conor; Lee, Kangho; Harvey, Andrew; Lynch, Peter; Gholamvand, Zahra; Zhang, Saifeng; Wang, Kangpeng; Moynihan, Glenn; Pokle, Anuj; Ramasse, Quentin M.; McEvoy, Niall; Blau, Werner J.; Wang, Jun; Abellan, Gonzalo; Hauke, Frank; Hirsch, Andreas; Sanvito, Stefano; O'Regan, David D.; Duesberg, Georg S.; Nicolosi, Valeria; Coleman, Jonathan N.
2015-10-01
Few-layer black phosphorus (BP) is a new two-dimensional material which is of great interest for applications, mainly in electronics. However, its lack of environmental stability severely limits its synthesis and processing. Here we demonstrate that high-quality, few-layer BP nanosheets, with controllable size and observable photoluminescence, can be produced in large quantities by liquid phase exfoliation under ambient conditions in solvents such as N-cyclohexyl-2-pyrrolidone (CHP). Nanosheets are surprisingly stable in CHP, probably due to the solvation shell protecting the nanosheets from reacting with water or oxygen. Experiments, supported by simulations, show reactions to occur only at the nanosheet edge, with the rate and extent of the reaction dependent on the water/oxygen content. We demonstrate that liquid-exfoliated BP nanosheets are potentially useful in a range of applications from ultrafast saturable absorbers to gas sensors to fillers for composite reinforcement.
Applying tracer techniques to NPP Cernavoda liquid effluents dispersed in Danube - Black Sea Canal
International Nuclear Information System (INIS)
Tritium routinely released as low activity liquid radioactive waste by Cernavoda nuclear power plant was used as a radiotracer to study longitudinal dispersion of Danube Black Sea Canal. A field experiment was carried out in which, after a tritium release, water was sampled downstream from three locations along the canal at periodic intervals. Tritium was measured with a low-background liquid scintillation system and the concentration time evolution for each location was obtained. In order to obtain the canal longitudinal dispersion efficiency, the Unit Peak Attenuation (UPA) curve was plotted. The UPA slope curve was used to construct software that can estimate propagation time of soluble tracer cloud and unit peak attenuation at any location from studied area. (authors)
Black holes in the lab: A review of accretion experiments using plasmas and liquid metals
Forest, Cary
2016-04-01
In this talk, we will survey recent liquid metal and plasma experiments attempting to study the magnetorotational instability, and ultimately, turbulent transport of angular momentum in laboratory plasmas that can mimic the Keplerian velocity profiles of accretion disks. We will describe the basic requirements of such experiments, the techniques used to create such laboratory experiments, and then review the results obtained thus far. The experiments fall into two camps, the first of which use resisitve liquid metal in couette flow geometry, and the second of which uses confined plasma that is stirred by induction on the plasma boundary. The regimes covered by liquid metals are compimentary: liquid metals are very resistive but nearly inviscid and may be appropriate for modeling protostellar disks, while hot plasmas are more viscous than resisitve and may be appropriate for hot accretion disks around black holes. Both approaches have overcome major experimental hurdles and now have dimensionless parameters that are in a regime where the MRI should be observed.
Energy Technology Data Exchange (ETDEWEB)
Yuan, H. C.; Oh, J.; Zhang, Y.; Kuznetsov, O. A.; Flood, D. J.; Branz, H. M.
2012-06-01
We report solar cells with both black Si antireflection and SiO2 surface passivation provided by inexpensive liquid-phase chemistry, rather than by conventional vacuum-based techniques. Preliminary cell efficiency has reached 16.4%. Nanoporous black Si antireflection on crystalline Si by aqueous etching promises low surface reflection for high photon utilization, together with lower manufacturing cost compared to vacuum-based antireflection coating. Ag-nanoparticle-assisted black Si etching and post-etching chemical treatment recently developed at NREL enables excellent control over the pore diameter and pore separation. Performance of black Si solar cells, including open-circuit voltage, short-circuit current density, and blue response, has benefited from these improvements. Prior to this study, our black Si solar cells were all passivated by thermal SiO2 produced in tube furnaces. Although this passivation is effective, it is not yet ideal for ultra-low-cost manufacturing. In this study, we report, for the first time, the integration of black Si with a proprietary liquid-phase deposition (LPD) passivation from Natcore Technology. The Natcore LPD forms a layer of <10-nm SiO2 on top of the black Si surface in a relatively mild chemical bath at room temperature. We demonstrate black Si solar cells with LPD SiO2 with a spectrum-weighted average reflection lower than 5%, similar to the more costly thermally grown SiO2 approach. However, LPD SiO2 provides somewhat better surface-passivation quality according to the lifetime analysis by the photo-conductivity decay measurement. Moreover, black Si solar cells with LPD SiO2 passivation exhibit higher spectral response at short wavelength compared to those passivated by thermally grown SiO2. With further optimization, the combination of aqueous black Si etching and LPD could provide a pathway for low-cost, high-efficiency crystalline Si solar cells.
Amran, A.; Harfianto, R.; Dewi, W. Y.; Beri, D.; Putra, A.
2016-02-01
Solubility dynamics of methyl yellow and carbon black in microemulsions and liquid crystals of water, non-ionic surfactants and cyclohexane system, have been investigated. Actually, solubility dynamics of these dyes both in microemulsion (w/o microemulsions) and the lamellar liquid crystal (LLC) were strongly related to the chemical composition, nature and characteristics of microemulsions and the lamellar liquid crystals.
International Nuclear Information System (INIS)
Graphical abstract: Thin films of CdS nanoparticles prepared rapidly at gas/liquid interface became black under visible light irradiation and exhibited enhanced photoelectrochemical performance in splitting water for hydrogen production in alkaline solution of methanol. - Highlights: • Thin films of CdS nanoparticles were facilely obtained at gas/liquid interface. • It involved reaction between CdCl2 and Na2S and assembly of CdS nanoparticles. • The film became black under visible light irradiation in methanol alkaline solution. • The phase composition of the black film was characterized by HRTEM and XRD. • The black film exhibited enhanced PEC performance for H2-production from water. - Abstract: Thin films of CdS nanoparticles were prepared rapidly at gas/liquid interface by dropping Na2S ethanol solution onto CdCl2 solution surface with the help of a surfactant (dodecyl sulfate). The photoelectrochemical cell that comprised of the prepared thin film photoanode of CdS nanoparticles and a Pt cathode generated a photocurrent density as high as 2.8 mA cm−2 at a bias voltage of 0.6 V under visible light illumination of 100 mW cm−2 in an alkaline solution of methanol, which was larger than that in other solutions under investigation. It can be ascribed to methanol-assisted transformation of CdS nanoparticles into black Cd/Cd(OH)2/CdS nanocomposites. At 2.8 mA, the decrease of bias voltage reached 2.49 V for hydrogen production with a solar-to-electricity efficiency of 4.65%
Use of black diamond-like carbon films as a contrast enhancement layer for liquid-crystal displays
Singh, B.; McClelland, S.; Tams, F., III; Halon, B.; Mesker, O.
1990-11-01
This paper describes the preparation of a highly durable single-layer pinhole-free abrasion-resistant chemically inert black diamondlike coating which is suitable for use as a contrast enhancement layer for liquid-crystal display devices. The diamondlike films prepared have an optical transmission of less than 2 percent over the visible spectrum, and a reflectance of about 20 percent. The coating is also electrically insulating and chemically compatible with liquid-crystal display materials. Data on the optical and mechanical properties of these films are presented.
Structure evolution of carbon black under ionic-liquid-assisted microwave irradiation
International Nuclear Information System (INIS)
The interactions between the carbon black (CB) and the ionic liquid (IL), 1-butyl-3-methyl-imiazolium hexafluorophosphate ([BMIM+][PF6-]), are firstly examined. The CB, mixed with the IL via simple blending, is then subjected to microwave (MW) irradiation to prepare the modified CB. The structure evolutions of the modified CB such as the microcrystalline structure and surface chemistry are revealed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and pore analysis. After mixing but before MW irradiation, the microcrystalline arrangement of CB turns to be more ordering and microcrystalline size (La) to be a little bigger but with a limited degree. Under MW irradiation, the IL undergoes severe decomposition. The combination of localized high temperature (proposed to be higher than 425 deg. C) and the decomposition of the IL leads to substantial structure changes of the CB. The graphitization of the CB surface, the disordering of the microcrystalline and the decrease in La are disclosed. In addition, compared with the untreated CB, the CB treated with IL-assisted MW irradiation is found to have much higher volume of the smaller mesopore.
International Nuclear Information System (INIS)
Full Text: There were fulfilled measurements of liquid zirconium density as a function of specific imparted energy, and then plotted as a function of temperature. Under heating, wire was flashed by a short laser pulse (6 ns). The shadow of Zr wire was registered by CCD camera. The method was checked by liquid iron density measurement and comparison with literature data. Dependencies of zirconium density and electrical resistivity up to 4100 K were obtained (for wire and foil specimens) an imparted energy and temperature. Specific heat capacity (cP) of liquid zirconium (from melting point up to 4100 K) was determined for flat surface and black body model. It reveals that in both cases over the narrow temperature range of 2150 - 2400 K (just after melting) cP diminishes up to usual values known from steady state measurements. Over the next wide temperature range of 2400 - 4100 K, a continuos increase of heat capacity is observed. Normal spectral emissivity (ελ) of liquid zirconium (at fast heating) depending on temperature (from 1800 K up to 4000 K) for λ = 855 nm was measured. Recommended data are given in the equation forms and in the table forms (step 10 K) of specific imparted energy, density, resistivity, heat capacity, and normal spectral emissivity of liquid zirconium against temperature up to 4100 K. Assessment of systematic errors of all measured values was fulfilled and standard deviations were calculated from average values. (author)
Constructing the AdS dual of a Fermi liquid: AdS Black holes with Dirac hair
\\vCubrović, Mihailo; Schalm, Koenraad
2010-01-01
We provide new evidence that the holographic dual to a strongly coupled charged Fermi Liquid has a non-zero fermion density in the bulk. We show that the pole-strength of the stable quasiparticle characterizing the Fermi surface is encoded in the spatially averaged AdS probability density of a single normalizable fermion wavefunction in AdS. Recalling Migdal's theorem which relates the pole strength to the Fermi-Dirac characteristic discontinuity in the number density at $\\ome_F$, we conclude that the AdS dual of a Fermi liquid is described by occupied on-shell fermionic modes in AdS. Encoding the occupied levels in the total probability density of the fermion field directly, we show that an AdS Reissner-Nordstr\\"{o}m black hole in a theory with charged fermions has a critical temperature, at which the system undergoes a first-order transition to a black hole with a non-vanishing profile for the bulk fermion field. Thermodynamics and spectral analysis confirm that the solution with non-zero AdS fermion-profil...
Optimization of liquid-fermentation technology for black garlic%液态黑蒜发酵工艺优化
Institute of Scientific and Technical Information of China (English)
罗仓学; 苏东霞; 陈树雨
2013-01-01
In this study, fresh garlic was fermented into black garlic in high temperature and high humidity conditions. Five influencing factors (temperature, time, material selection, material-to-liquid ratio, and crushing granularity) were studied during fermentation process. Combining the measurement of soluble sugar content, total phenolic content, and superoxide dismutase (SOD)activity with sensory evaluation, we determined that it was mainly the Maillard reaction during the fermentation process. We selected 70, 80, and 85℃ for constant-temperature fermented garlic puree. On the basis of the effect of temperature on the black garlic fermentation we determined the time range of the subsection temperature-changing fermentation. Using a colorimeter, we dynamically detected the change of chromatic (L value) during the black garlic fermentation process, and we detected the content of soluble sugar, total phenolic content, and SOD activity. We found that the formation of garlic melanin was related to temperature and time. Garlic in high-temperature pre-fermentation conditions may form a large quantity of melanin. On the basis of constant temperature fermentation, the garlic puree was fermented with the subsection temperature-changing fermentation. The combinations of the selected temperature were:65-80, 80-70, 85-65, 85-70℃. The pre-fermentation time was 5-6 d, and the post-fermentation time was 11-13d. Combined sensory evaluation with detection of the content of soluble sugar, total phenolic content, and SOD activity, we determined the temperature and time combinations of the subsection temperature-changing fermentation. On the basis of the subsection temperature-changing fermentation, material selection, material-to-liquid ratio, and crushing granularity had been systematically studied to determine the optimum technology parameters of the liquid black garlic fermentation. Data were expressed in terms of means and standard deviations and were analyzed by Duncan
Cho, Hyun-jeong; Kim, Hye-jin; Son, Byeong-cheol; Jo, Dong-keun; Cho, Byung-lim
2013-05-01
Black ginseng is produced by steaming a ginseng root followed by drying repeatedly 9 times during the process and it is changed to be black color, so it is known that a black ginseng has more contents of saponins than red ginseng. However a fake black ginseng which is produced to be black color at high temperature in a short period of time generate carcinogenic benzo[a]pyrene(BaP) through the process. In this year, maximum residue level(MRL) for BaP was established to 2 ug/kg in black ginseng and more sensitive method was developed to quantitatively analyze the BaP by high performance liquid chromatography (HPLC) coupling with florescence detector and tandem mass spectrometry (atmospheric pressure chemical ionization-MS/MS). Chromatographic separation was performed on a Supelcosil™ LC-PAH column (3 μm, 3 mm x 50 mm). Mobile phase A was water and mobile phase B was acetonitrile. BaP was exactly separated from other 15 polycyclic aromatic hydrocarbons (PAHs) which have been selected as priority pollutants by the US Environmental Protection Agency (EPA). Linearity of detection was in the range of 0.2~20 μg/kg and limit of detection (LOD) for BaP was lower than 0.1 μg/kg, limit of quantification (LOQ) was 0.2 μg/kg. The recovery of Bap was 92.54%+/-6.3% in black ginseng.
Institute of Scientific and Technical Information of China (English)
Niu Yan-Xiong; Yang Hai-Lin; Zhang Peng; Shen Xue-Ju; Jiang Nan; Chen Yan; Tang Fang
2008-01-01
The optical limiting properties of the mixed liquid of carbon black suspensions(CBS)and green tea solution were studied by using an 8 ns laser pulse at 532nm.The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10 Hz repetition frequencies with nanosecond laser pulse.The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10 Hz repetition frequency is lower than at 5 Hz repetition frequency.The possible reasons for the influence of the repetition frequency on the samples are discussed.And by observing the optical radiant distributions when the laser pulse passing through different samples,a possible mechanism for the observed effects is suggested.At the same time,the result shows that the optical limiting of CBS is the dominant factor to optical limiting ofthe mixed liquid.
Niu Yan-, Xiong; Yang, Hai-Lin; Zhang, Peng; Shen, Xue-Ju; Jiang, Nan; Chen, Yan; Tang, Fang
2008-09-01
The optical limiting properties of the mixed liquid of carbon black suspensions (CBS) and green tea solution were studied by using an 8 ns laser pulse at 532 nm. The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10 Hz repetition frequencies with nanosecond laser pulse. The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10 Hz repetition frequency is lower than at 5 Hz repetition frequency. The possible reasons for the influence of the repetition frequency on the samples are discussed. And by observing the optical radiant distributions when the laser pulse passing through different samples, a possible mechanism for the observed effects is suggested. At the same time, the result shows that the optical limiting of CBS is the dominant factor to optical limiting of the mixed liquid.
International Nuclear Information System (INIS)
The optical limiting properties of the mixed liquid of carbon black suspensions (CBS) and green tea solution were studied by using an 8 ns laser pulse at 532 nm. The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10 Hz repetition frequencies with nanosecond laser pulse. The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10 Hz repetition frequency is lower than at 5 Hz repetition frequency. The possible reasons for the influence of the repetition frequency on the samples are discussed. And by observing the optical radiant distributions when the laser pulse passing through different samples, a possible mechanism for the observed effects is suggested. At the same time, the result shows that the optical limiting of CBS is the dominant factor to optical limiting of the mixed liquid. (classical areas of phenomenology)
DEFF Research Database (Denmark)
Nielsen, Inge Lise F.; Ravn-Haren, Gitte; Magnussen, Eva Loftin;
2003-01-01
Quantitative determinations of the four black currant anthocyanins, cyanidin 3-O-beta-glucoside, cyanidin 3-O-beta-rutinoside, delphinidin 3-O-beta-glucoside, and delphinidin 3-O-beta-rutinoside, were achieved in black currant juices by a rapid and sensitive high-performance liquid chromatographic...... (HPLC) method. The method was validated, and quantification of anthocyanins in 13 commercially available black currant beverages was demonstrated. To optimize the handling of anthocyanin-containing samples, the pH-dependent stability of the anthocyanins was investigated. Four anthocyanins were incubated...... for 24 h in aqueous solutions at 13 different pH levels between 0.6 and 5.2, after which the samples were analyzed by HPLC. More than 90% of each anthocyanin remained intact up to pH 3.3. At pH 3.8 a local minimum in stability was detected, and at pH >4.5 the stability rapidly decreased. The...
Luo, Yanling; Li, Yanlei; Li, Zhanqing
2006-12-01
An electrically conductive composite of polyurethane pre-polymers was prepared by an intramolecular hydrogen transfer reaction using a reactive hydroxyl-terminated polybutadiene (HTPB) liquid rubber oligopolymer as a reactant, toluene diisocyanate (TDI) as a curing agent and carbon black (CB) as a conductive filler. The influence of the component ratios, types of carbon black particles, curing temperatures and chain-extending agents such as glycerine and triethanolamine on the responsiveness and reversibility of HTPB/TDI/CB composite films was investigated. The structural characterization of the curing materials was conducted on a FT-IR spectrometer. The experimental results indicated that a higher response behavior of HTPB/TDI/CB composite films occurred in non-polar solvent vapors than with polar solvent vapors. The response intensity of the composite films enhanced with increased TDI content and the introduction of chain-extending agents. The responsivity of the films to benzene vapor reached 106 times the original value, but the responsive time and recovery time were prolonged at higher curing temperatures. The response mechanism for the films was elucidated based on the relationship between soft chain segments and hard chain segments.
Sereshti, Hassan; Samadi, Soheila; Jalali-Heravi, Mehdi
2013-03-01
Ultrasound assisted extraction (UAE) followed by dispersive liquid-liquid microextraction (DLLME) was used for extraction and preconcentration of volatile constituents of six tea plants. The preconcentrated compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Totally, 42 compounds were identified and caffeine was quantitatively determined. The main parameters (factors) of the extraction process were optimized by using a central composite design (CCD). Methanol and chloroform were selected as the extraction solvent and preconcentration solvent, respectively .The optimal conditions were obtained as 21 in for sonication time; 32°C for temperature; 27 L for volume of extraction solvent and 7.4% for salt concentration (NaCl/H(2)O). The determination coefficient (R(2)) was 0.9988. The relative standard deviation (RSD %) was 4.8 (n=5), and the enhancement factors (EFs) were 4.0-42.6. PMID:23375769
Xu, Jing-Yin; Gao, Lin-Feng; Hu, Chen-Xia; Zhu, Zhi-Yuan; Zhao, Min; Wang, Qiang; Zhang, Hao-Li
2016-06-21
Ultrathin uniform BP nanosheets with lateral dimensions of up to several tens of micrometers were prepared via a small molecule-assisted liquid phase exfoliation method, which exhibited attractive electron accepting abilities from photosensitizers and was thus promising in diverse applications such as photocatalysis and photovoltaics. PMID:27265350
DEFF Research Database (Denmark)
Langkjær, Michael Alexander
2012-01-01
Pop musicians performing in black stage costume take advantage of cultural traditions relating to matters black. Stylistically, black is a paradoxical color: although a symbol of melancholy, pessimism, and renunciation, black also expresses minimalist modernity and signifies exclusivity (as...... is hinted by Rudyard Kipling’s illustration of ‘The [Black] Cat That Walked by Himself’ in his classic children’s tale). It was well understood by uniformed Anarchists, Fascists and the SS that there is an assertive presence connected with the black-clad figure. The paradox of black’s abstract elegance......-styled references to, among other things, the culturally and ideologically effervescent interwar-period have made me curious as to what alternative possibilities – for instance ‘emancipation’ – a comparative analysis might disclose concerning the visual rhetoric of black. Thus, in conclusion, it is briefly...
International Nuclear Information System (INIS)
A black ring is a five-dimensional black hole with an event horizon of topology S1 x S2. We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)
Hraba, Joseph; Siegman, Jack
1974-01-01
Black militancy is treated as an instance of class consciousness with criteria and scales developed to measure black consciousness and "self-placement" into black consciousness. These dimensions are then investigated with respect to the social and symbolic participation in the ideology of the black movement on the part of a sample of black…
Hennigar, Robie A; Tjoa, Erickson
2016-01-01
We present what we believe is the first example of a "$\\lambda$-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 AdS 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.
... eyesight if not treated. If both eyes are black after a head injury, it could signify a skull fracture or other serious injury. Next Black Eye Symptoms Related Ask an Ophthalmologist Answers How ...
... diuretic to increase urine flow. Some people use black tea for preventing tooth decay and kidney stones. In combination with various other products, black tea is used for weight loss. In foods, ...
Luminet, Jean-Pierre
1992-09-01
Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.
Mahmood, Shahid; Khalid, Azeem; Arshad, Muhammad; Ahmad, Riaz
2015-11-01
This study demonstrates the role of electron shuttles and trace metals in the biotransformation of azo dye reactive black-5 and hexavalent chromium (CrVI) that are released simultaneously in tannery effluent. Previously isolated bacterial strain Pseudomonas putida KI was used for the simultaneous reduction of the dye (100 mg L(-1)) and CrVI (2 mg L(-1)) in a mineral salts medium (MSM). Among various trace metals, only Cu(II) had a stimulating effect on the bacterial-mediated reduction process. Application of electron shuttles such as hydroquinone and uric acid at a low concentration (1mM) had a positive effect on the reduction process and caused simultaneous reduction of 100% dye and 97% CrVI in 12-18 h. Mannitol, EDTA and sodium benzoate at all concentrations (ranging from 1 to 9 mM) showed an inhibitory effect on the reduction of reactive black-5 and CrVI. An inverse linear relationship between the velocity of reaction (V) and the concentration [S] of electron shuttles was observed. The results imply that both types and concentration of an electron shuttle and trace metals can affect the simultaneous reduction of reactive black-5 and CrVI. PMID:25556007
Melliou, Eleni; Zweigenbaum, Jerry A; Mitchell, Alyson E
2015-03-11
The chemical composition of finished table olive products is influenced by the olive variety and the processing method used to debitter or cure table olives. Herein, a rapid ultrahigh-pressure liquid chromatography triple-quadrupole tandem mass spectrometry method, using dynamic multiple reaction monitoring, was developed for the quantitation of 12 predominant phenolic and secoiridoid compounds in olive fruit, including hydroxytyrosol, oleuropein, hydroxytyrosol-4-O-glucoside, luteolin-7-O-glucoside, rutin, verbascoside, oleoside-11-methyl ester, 2,6-dimethoxy-p-benzoquinone, phenolic acids (chlorogenic and o-coumaric acids), oleuropein aglycone, and ligstroside aglycone. Levels of these compounds were measured in fresh and California-style black ripe processed Manzanilla olives and two dry salt-cured olive varieties (Mission from California and Throuba Thassos from Greece). Results indicate that the variety and debittering processing method have strong impact on the profile of phenolic and secoiridoid compounds in table olives. The dry salt-cured olives contained higher amounts of most compounds studied, especially oleuropein (1459.5 ± 100.1 μg/g), whereas California-style black ripe olives had a significant reduction or loss of these bioactive compounds (e.g., oleuropein level at 36.7 ± 3.1 μg/g). PMID:25668132
Directory of Open Access Journals (Sweden)
Angela Khristin Brown
2013-07-01
Full Text Available The migration of blacks in North America through slavery became united. The population of blacks past downs a tradition of artist through art to native born citizens. The art tradition involved telling stories to each generation in black families. The black culture elevated by tradition created hope to determine their personal freedom to escape from poverty of enslavement and to establish a way of life through tradition. A way of personal freedoms was through getting a good education that lead to a better foundation and a better way of life.
Are black holes totally black?
Grib, A A
2014-01-01
Geodesic completeness needs existence near the horizon of the black hole of "white hole" geodesics coming from the region inside of the horizon. Here we give the classification of all such geodesics with the energies $E/m \\le 1$ for the Schwarzschild and Kerr's black hole. The collisions of particles moving along the "white hole" geodesics with those moving along "black hole" geodesics are considered. Formulas for the increase of the energy of collision in the centre of mass frame are obtained and the possibility of observation of high energy particles arriving from the black hole to the Earth is discussed.
Electrically actuated liquid iris.
Xu, Miao; Ren, Hongwen; Lin, Yi-Hsin
2015-03-01
We report an adaptive iris using dielectric liquids and a radial-interdigitated electrode. A black liquid is confined by a circular gasket with a donut shape. The surrounding of the black liquid is filled with an immiscible liquid. In the relaxing state, the black liquid obtains the largest clear aperture. By applying a voltage, the surface of the black liquid is stretched by the generated dielectric force, resulting in a reduction of its aperture. For the demonstrated iris, the diameter of the aperture can be changed from ∼4.7 mm to ∼1.2 mm when the voltage is applied from 0 to 70 V(rms). The aperture ratio is ∼94%. Owing to the radial-interdigitated electrode, the aperture size of the iris can be effectively switched with a reasonably fast response time. The optical switch is polarization-insensitive. The potential applications of our iris are light shutters, optical attenuators, biomimicry, and wearable devices. PMID:25723444
International Nuclear Information System (INIS)
One way for states and subnational groups to acquire material, knowledge and equipment necessary to build a nuclear weapon or device are illegal transactions. These were singular in the past and did not cause the development of a nuclear black market. But all necessary components of a functioning black market exist. Therefore the further spread and extension of the use of nuclear power would enhance the threat of a nuclear black market, if the trade and use of specific nuclear material is not abandoned worldwide. (orig.)
Thermodynamics of rotating black holes and black rings: phase transitions and thermodynamic volume
Altamirano, Natacha; Mann, Robert B; Sherkatghanad, Zeinab
2014-01-01
In this review we summarize, expand, and set in context recent developments on the thermodynamics of black holes in extended phase space, where the cosmological constant is interpreted as thermodynamic pressure and treated as a thermodynamic variable in its own right. We specifically consider the thermodynamics of higher-dimensional rotating asymptotically flat and AdS black holes and black rings in a canonical (fixed angular momentum) ensemble. We plot the associated thermodynamic potential-the Gibbs free energy-and study its behaviour to uncover possible thermodynamic phase transitions in these black hole spacetimes. We show that the multiply-rotating Kerr-AdS black holes exhibit a rich set of interesting thermodynamic phenomena analogous to the "every day thermodynamics" of simple substances, such as reentrant phase transitions of multicomponent liquids, multiple first-order solid/liquid/gas phase transitions, and liquid/gas phase transitions of the Van der Waals type. Furthermore, the reentrant phase tran...
... product containing black tea extract plus green tea extract, asparagus, guarana, kidney bean, and mate along with a combination of kidney bean pods, garcinia, and chromium yeast for 12 weeks does not reduce body weight ...
Energy Technology Data Exchange (ETDEWEB)
Pettersson, Karin; Harvey, Simon [Department of Energy and Environment/Heat and Power Technology, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden)
2010-02-15
Black liquor gasification (BLG) is currently being developed as an alternative technology for energy and chemical recovery at chemical pulp mills. This study examines how different assumptions regarding systems surrounding the pulp mill affect the CO{sub 2} emission balances for different BLG concepts. The syngas from the gasification process can be used for different applications; this study considers production of renewable motor fuels and electricity generation. Both a market pulp mill and an integrated pulp and paper mill are considered as host mill for the BLG plant. Furthermore, the consequences of limited availability of biomass are shown, i.e., increasing the use of biomass in a mill is not necessarily CO{sub 2}-neutral. The results show that the potential to reduce CO{sub 2} emissions by introducing BLG is generally much higher for a market pulp mill than for an integrated pulp and paper mill. Electricity generation from the syngas is favoured when assuming high grid electricity CO{sub 2} emissions whereas motor fuel production is favoured when assuming low grid electricity CO{sub 2} emissions. When considering the consequences of limited availability of biomass, the CO{sub 2} emission balances are strongly affected, in some cases changing the results from a decrease to an increase of the CO{sub 2} emissions. (author)
Suyanto, Hery
2016-03-01
The aim of this research is to characterize black stone and also to know the capability to adsorb Ag and Pb elements in solution. All analysis in this research used laser-induced breakdown spectroscopy (commercial LIBS) method with laser energy of 120 mJ, accumulation 4, gate delay 1 µs and air surrounding gas at 1 atmosphere. Before soaked in 20 ml solution containing Ag and Pb of 40 ppm in 1 hour, the stone was analyzed by LIBS and it contains the main elements such as Ca, Mn, Si, K, Fe, Mg, Mo, H, O and Na until 16 laser shots. However, after immersed in solution, the stone contains impurities Ag and Pb elements with signal to noise ratio (SNR) of 9.5 and 1.2 respectively. Based on this data, the stone is predicted to be able to adsorb Ag element in solution till 12.7 ppm. The data also show that Ag element was adsorbed homogenously by stone till 16th laser shots, although it was washed with flowing demineralized water before it was analyzed.
P-V Criticality of Modified BTZ Black Hole
Sadeghi, J.; Kubeka, A. S.
2016-05-01
In this paper, we investigate the BTZ black hole in P-V critical point of view. As we know, the BTZ black hole does not have P-V critical behavior. So in this case, we introduce some anstaz that give us the modified BTZ black hole. Finally, we show that this modified BTZ black hole is satisfied by the equation of state of Liquid-gas phase transition.
Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S
2013-01-01
Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami
Robert C. Merton; Myron S. Scholes
2013-01-01
ReprintThis article was originally published by Wiley for the American Finance Association (Merton RC, Scholes MS. 1995. Fischer Black. J. Finance 50(5):1359–70). It is reprinted with permission from John Wiley and Sons © 1995. Reference formatting was updated to facilitate linking.
Radionic nonuniform black strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2004-01-01
Nonuniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a nontrivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes a dilatonic black hole in the single brane limit and reduces to the Reissner-Nordström black hole in the close limit of two-branes. The stability of solutions is demonstrated using catastrophe theory. From the bulk point of view, the black strings are proved to be nonuniform. Nevertheless, the zeroth law of black hole thermodynamics still holds.
Kim, Sung Phil; Park, Sun Ok; Lee, Sang Jong; Nam, Seok Hyun; Friedman, Mendel
2014-03-19
The present study investigated the antibacterial effect of a bioprocessed polysaccharide (BPP) isolated from Lentinus edodes liquid mycelial culture supplemented with black rice bran against murine salmonellosis. BPP was not bactericidal in vitro, it did, however, stimulate uptake of the bacteria into RAW 264.7 murine macrophage cells, as indicated by increased colony-forming unit (CFU) counts of the contents of the lysed macrophages incubated with Salmonella Typhimurium for 30 and 60 min. Two hours postinfection, the bacterial counts drastically increased in the macrophages, but 4 and 8 h postinfection BPP extract-treated cells showed lower bacterial counts than the vehicle (saline phosphate pH 7.4 buffer, PBS)-treated control. BPP elicited altered morphology and markedly elevated inducible nitric oxide (NO) synthase (iNOS) mRNA and protein expression in the infected macrophage cells. BPP also activated leukocytes in S. Typhimurium-infected mice, as determined by spleen lymphocyte proliferation and IFN-γ levels in mice sera. ELISA analysis on cytokine production by Th1 and Th2 immune cells from splenocytes of infected mice showed significant increases in the levels of the following Th1 cytokines: IL-1β, IL-2, IL-6, and IL-12. Histology assays of the livers of mice infected with a sublethal dose (1 × 10(4) CFU) of S. Typhimurium showed that BPP, administered daily through an intraperitoneal (ip) or oral route, protected against necrosis of the liver, a biomarker of in vivo salmonellosis. The lifespan of mice similarly infected with a lethal dose of S. Typhimurium (1 × 10(5) CFU) was significantly extended by ip injection or oral administration of the BPP without side effects. These results suggest that the activity of BPP against bacterial infection in mice occurs mainly through the activation of macrophage-mediated immune response resulting from augmented Th1 immunity. The significance of the results for microbial food safety and human health and further
Black Silicon Solar Cells with Black Ribbons
DEFF Research Database (Denmark)
Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io;
2016-01-01
We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies in the...
International Nuclear Information System (INIS)
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
Black Entrepreneurship in America.
Green, Shelley; Pryde, Paul
The economic condition of black Americans is discussed, proceeding from the assumption that black economic progress does not depend on a renewed struggle for unobtained civil rights, but rather on the creative response of black Americans to economic opportunity and problems. In the long run, black economic development must rely on the…
Long, Richard A.
1970-01-01
Indicates tendencies dangerous to the basic purpose of Black Studies, and identifies four external challeges--imperialism, paternalism, nihilism, and materialism. An internal challenge is considered to be the use of European and Establishment constructs to analyze black reality. (DM)
Hayward, Sean A.
2008-01-01
This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping h...
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.
Strominger, Andrew
1993-01-01
The quantum statistics of charged, extremal black holes is investigated beginning with the hypothesis that the quantum state is a functional on the space of closed three-geometries, with each black hole connected to an oppositely charged black hole through a spatial wormhole. From this starting point a simple argument is given that a collection of extremal black holes obeys neither Bose nor Fermi statistics. Rather they obey an exotic variety of particle statistics known as ``infinite statist...
Gao, C. J.; Zhang, S. N.
2006-01-01
The exact solutions of electrically charged phantom black holes with the cosmological constant are constructed. They are labelled by the mass, the electrical charge, the cosmological constant and the coupling constant between the phantom and the Maxwell field. It is found that the phantom has important consequences on the properties of black holes. In particular, the extremal charged phantom black holes can never be achieved and so the third law of thermodynamics for black holes still holds. ...
Kinetics and mechanism of nitric oxidation of carbon black
International Nuclear Information System (INIS)
After some generalities about carbon blacks (preparation by various processes, structure, industrial use), the author notices that carbon black is often dispersed in aqueous solutions and, as it is hydrophobic, must therefore be submitted to treatment to become hydrophilic. Oxidation in liquid phase suits perfectly, and oxidation by nitric acid gives good results. Thus, this research thesis reports the study of the oxidation reaction mechanism in the case of oxidation of carbon black by nitric acid in aqueous solution. After having defined the different types of carbon blacks used in this study, and given an overview of the oxidation process (methods, purification and purity control of the obtained blacks, determination of the efficiency in terms of oxidised or purified black, difficulties faced during the elemental analysis of oxidised blacks), the author discusses the mechanism of formation of carbon dioxide during the oxidation of Philblack 0 carbon black by nitric acid. He reports the study of the oxidation kinetics, and the study of a thermal treatment of oxidised carbon blacks. The last part reports the study of the evolution of various properties of carbon blacks during oxidation: specific surface (BET method), density, examination by electronic microscopy and X-rays, magnetic susceptibility
Rector, Theresa A.
1982-01-01
Traces the contributions of Black Roman Catholic nuns to Black education in the United States since the early 1800s. Also shows that, despite declining membership, the three existing religious orders continue to be active in Black education and social change. (GC)
Black Holes in Higher Dimensions (Black Strings and Black Rings)
Kleihaus, Burkhard
2016-01-01
The last three years have again seen new exciting developments in the area of higher dimensional black objects. For black objects with noncompact higher dimensions, the solution space was exlored further within the blackfold approach and with numerical schemes, yielding a large variety of new families of solutions, while limiting procedures created so-called super-entropic black holes. Concerning compact extra dimensions, the sequences of static nonuniform black strings in five and six dimensions were extended to impressively large values of the nonuniformity parameter with extreme numerical precision, showing that an oscillating pattern arises for the mass, the area or the temperature, while approaching the conjectured double-cone merger solution. Besides the presentation of interesting new types of higherdimensional solutions, also their physical properties were addressed in this session. While the main focus was on Einstein gravity, a significant number of talks also covered Lovelock theories.
Nonstationary analogue black holes
International Nuclear Information System (INIS)
We study the existence of analogue nonstationary spherically symmetric black holes. The prime example is the acoustic model see Unruh (1981 Phys. Rev. Lett. 46 1351). We consider also a more general class of metrics that could be useful in other physical models of analogue black and white holes. We give examples of the appearance of black holes and of disappearance of white holes. We also discuss the relation between the apparent and the event horizons for the case of analogue black holes. In the end we study the inverse problem of determination of black or white holes by boundary measurements for the spherically symmetric nonstationary metrics. (paper)
Levin, Janna; D'Orazio, Daniel
2016-03-01
Black holes are dark dead stars. Neutron stars are giant magnets. As the neutron star orbits the black hole, an electronic circuit forms that generates a blast of power just before the black hole absorbs the neutron star whole. The black hole battery conceivably would be observable at cosmological distances. Possible channels for luminosity include synchro-curvature radiation, a blazing fireball, or even an unstable, short-lived black hole pulsar. As suggested by Mingarelli, Levin, and Lazio, some fraction of the battery power could also be reprocessed into coherent radio emission to populate a subclass of fast radio bursts.
Alkac, Gokhan; Tekin, Bayram
2016-01-01
Asymptotically flat black holes in $2+1$ dimensions are a rarity. We study the recently found black flower solutions (asymptotically flat black holes with deformed horizons), static black holes, rotating black holes and the dynamical black flowers (black holes with radiative gravitons ) of the purely quadratic version of new massive gravity. We show how they appear in this theory and we also show that they are also solutions to the infinite order extended version of the new massive gravity, that is the Born-Infeld extension of new massive gravity with an amputated Einsteinian piece. The same metrics also solve the topologically extended versions of these theories, with modified conserved charges and the thermodynamical quantities, such as the Wald entropy. Besides these we find new conformally flat radiating type solutions to these extended gravity models. We also show that these metrics do not arise in Einstein's gravity coupled to physical perfect fluids.
Black-on-white polymer-stabilized cholesteric formulations
West, John L.; Magyar, Gregory R.; Francl, James J.; Nixon, Christine M.
1995-08-01
Recent research by Doane, Yang, and Chien demonstrated the use of cholesteric liquid crystals in multiplexed, high resolution, reflective diplays. These materials utilize the bistability of the cholesteric planar and focal conic states for displays with a colored image on a black background. Many commercial applications of these materials, such as electronic books and newspapers, portable faxes and personal data assistants, require, or at least prefer, black-on- white images. We report on relatively high polymer content (equalsV 20% by weight) dispersions of cholesteric liquid crystals that produce a white, reflecting, planar state. The polymer network appears to form cholesteric domains with varying pitch lengths resulting in planar states that reflect in the red, green, and blue portions of the spectrum. Utilizing a black absorbing layer behind a display using these materials offers white images on a black background, or vice-versa.
Heinen, Marco; Schnyder, Simon K.; Brady, John F.; Löwen, Hartmut
2015-01-01
We introduce fractal liquids by generalizing classical liquids of integer dimensions d=1,2,3 to a fractal dimension df. The particles composing the liquid are fractal objects and their configuration space is also fractal, with the same non-integer dimension. Realizations of our generic model system include microphase separated binary liquids in porous media, and highly branched liquid droplets confined to a fractal polymer backbone in a gel. Here we study the thermodynamics and pair correlati...
Assay of carbon nanoparticles in liquids.
Nawi, Yehuda; Sasson, Yoel; Dolgin, Bella
2016-04-01
The critical assay of carbon black concentration suffers from the lack of available methods, especially in-situ methods suitable for nanoparticles. We propose a useful tool for monitoring carbon nanoparticles concentration in liquids by means of RGB imaging, fluorescence and conductivity measurements. In this study carbon black particles of 25-75nm size were dispersed within two types of "green" liquids (1-butyl-3-methyl imidazolium based ionic liquids and glycerol) and the effect of carbon nanoparticles concentration on the liquids properties was measured. The conductivity of all the liquids increased with carbon concentration, while the slope of the curve was liquid dependent. The fluorescence intensity of ionic liquids decreased dramatically even when a small amount of carbon was added, while water-containing ionic liquids had a more moderate behavior. Glycerol has no native fluorescence, therefore, a known tracer present in soot (dibenzothiophene), having a characteristic fluorescence monitored by synchronous scan mode, was used. The carbon black effect on RGB imaging shows a linear dependence, while the red counts decreases with contamination. The proposed methods are simple and low-cost but nonetheless sensitive. PMID:26780588
Phase transitions of black holes in massive gravity
Fernando, Sharmanthie
2016-01-01
In this paper we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter. We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first order phase transition between small and large black hole for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a Van der Waals fluid. The coexistence curves for the small and large black hole branches are also discussed in detail.
Stimulated Black Hole Evaporation
Spaans, Marco
2016-01-01
Black holes are extreme expressions of gravity. Their existence is predicted by Einstein's theory of general relativity and is supported by observations. Black holes obey quantum mechanics and evaporate spontaneously. Here it is shown that a mass rate $R_f\\sim 3\\times 10^{-8} (M_0/M)^{1/2}$ $M_0$ yr$^{-1}$ onto the horizon of a black hole with mass $M$ (in units of solar mass $M_0$) stimulates a black hole into rapid evaporation. Specifically, $\\sim 3 M_0$ black holes can emit a large fraction of their mass, and explode, in $M/R_f \\sim 3\\times 10^7 (M/M_0)^{3/2}$ yr. These stimulated black holes radiate a spectral line power $P \\sim 2\\times 10^{39} (M_0/M)^{1/2}$ erg s$^{-1}$, at a wavelength $\\lambda \\sim 3\\times 10^5 (M/M_0)$ cm. This prediction can be observationally verified.
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.
Ahn, Eun-Joo; Cavaglia, Marco
2003-01-01
Production of high-energy gravitational objects is a common feature of gravitational theories. The primordial universe is a natural setting for the creation of black holes and other nonperturbative gravitational entities. Cosmic black holes can be used to probe physical properties of the very early universe which would usually require the knowledge of the theory of quantum gravity. They may be the only tool to explore thermalisation of the early universe. Whereas the creation of cosmic black ...
Lettman-Hicks, Sharon
2014-01-01
The New Black is a documentary that tells the story of how the African American community is grappling with the gay rights issue in light of the recent gay marriage movement and the fight over Civil Rights. The film documents activities, families and clergy on both sides of the campaign to legalize gay marriage and examines homophobia in the Black community's institutional pillar, the Black church, and reveals the Christian right wing's strategy of exploiting this phenomenon in order to pursu...
Black branes as piezoelectrics.
Armas, Jay; Gath, Jakob; Obers, Niels A
2012-12-14
We find a realization of linear electroelasticity theory in gravitational physics by uncovering a new response coefficient of charged black branes, exhibiting their piezoelectric behavior. Taking charged dilatonic black strings as an example and using the blackfold approach we measure their elastic and piezolectric moduli. We also use our results to draw predictions about the equilibrium condition of charged dilatonic black rings in dimensions higher than six. PMID:23368298
Directory of Open Access Journals (Sweden)
Meng Sun
2015-08-01
Full Text Available We give a general illumination of a rotating black string falling into a rotating horizon in dimension D=5. It is a configuration of one smooth intersection between these two objects when the spacetime is axisymmetric and in the limit that the thickness of the black hole is much larger than the thickness of the black string. Following this configuration, we further extend them to the rotating and charged flows.
Hod, Shahar
2015-01-01
The holographic principle has taught us that, as far as their entropy content is concerned, black holes in $(3+1)$-dimensional curved spacetimes behave as ordinary thermodynamic systems in flat $(2+1)$-dimensional spacetimes. In this essay we point out that the opposite behavior can also be observed in black-hole physics. To show this we study the quantum Hawking evaporation of near-extremal Reissner-Nordstr\\"om black holes. We first point out that the black-hole radiation spectrum departs from the familiar radiation spectrum of genuine $(3+1)$-dimensional perfect black-body emitters. In particular, the would be black-body thermal spectrum is distorted by the curvature potential which surrounds the black hole and effectively blocks the emission of low-energy quanta. Taking into account the energy-dependent gray-body factors which quantify the imprint of passage of the emitted radiation quanta through the black-hole curvature potential, we reveal that the $(3+1)$-dimensional black holes effectively behave as p...
Begelman, Mitchell C
2003-06-20
Black holes are common objects in the universe. Each galaxy contains large numbers-perhaps millions-of stellar-mass black holes, each the remnant of a massive star. In addition, nearly every galaxy contains a supermassive black hole at its center, with a mass ranging from millions to billions of solar masses. This review discusses the demographics of black holes, the ways in which they interact with their environment, factors that may regulate their formation and growth, and progress toward determining whether these objects really warp spacetime as predicted by the general theory of relativity. PMID:12817138
International Nuclear Information System (INIS)
The quantum statistics of charged, extremal black holes is investigated beginning with the hypothesis that the quantum state is a functional on the space of closed three-geometries, with each black hole connected to an oppositely charged black hole through a spatial wormhole. From this starting point a simple argument is given that a collection of extremal black holes obeys neither Bose nor Fermi statistics. Rather, they obey an exotic variety of particle statistics known as ''infinite statistics'' which resembles that of distinguishable particles and is realized by a q deformation of the quantum commutation relations
Hajdukovic, D
2006-01-01
We speculate about impact of antigravity (i.e. gravitational repulsion between matter and antimatter) on the creation and emission of particles by a black hole. If antigravity is present a black hole made of matter may radiate particles as a black body, but this shouldn't be true for antiparticles. It may lead to radical change of radiation process predicted by Hawking and should be taken into account in preparation of the attempt to create and study mini black holes at CERN. Gravity, including antigravity is more than ever similar to electrodynamics and such similarity with a successfully quantized interaction may help in quantization of gravity.
Neves, J C S
2015-01-01
In this work, we have deformed regular black holes which possess a general mass term described by a function which generalizes the Bardeen and Hayward mass terms. Using linear constraints in the energy-momentum tensor, the solutions are either regular or singular. That is, with this approach, it is possible to generate singular black holes from regular black holes and vice versa. Moreover, contrary to the Bardeen and Hayward regular solutions, the regular deformed metrics may violate the weak energy condition despite the presence of the spherical symmetry. Some comments on accretion of deformed black holes in cosmological scenarios are made.
Ronay, Valerie; Attin, Thomas
2011-01-01
The purpose of this review was to summarise the fundamentals about black stain, its diagnosis and possible differential diagnoses as well as its microbiology and therapy. In addition, various studies investigating the relationship between black stain and dental caries are examined. Many studies report lower caries prevalence in children with black stain, but this finding could not be confirmed by all authors. Also, a negative relation between degree of staining and caries severity has been described. Reasons for these results are not yet clear but it was speculated that they are related to the specific oral microflora described in black stain-affected individuals. PMID:21594205
"Black Capitalism": Toward Controlled Development of Black America
Wright, Robert E.
1969-01-01
Argues in favor of the connotation of the term "Black capitalism as the accumulation of capital resources by the Black people in a collective fashion for the benefit of the masses of Black people. (RJ)
Institute of Scientific and Technical Information of China (English)
黄国培; 陈颖军; 田崇国; 刘莺
2016-01-01
苯多羧酸法是定量检测黑碳和溶解态黑碳的重要分子标志物法，其中苯多羧酸和硝基苯多羧酸的分离和定量是关键环节。本文建立了苯多羧酸和硝基苯多羧酸的液相色谱-质谱分析方法，利用质谱的定性能力解决了部分苯多羧酸和硝基苯多羧酸化合物在缺乏标准品情况下的定性问题。用 Phenomenex Synergi Polar RP 分离柱，柱温为35℃，流动相为0.5％（体积分数）甲酸水溶液和甲醇，流速为0.5 mL／min，梯度洗脱，以电喷雾离子源负离子全扫描和选择扫描模式进行离子阱质谱检测，同时利用串联的二极管阵列检测器采集三维紫外光谱数据。在实际样品检测中，14个含3个及以上羧基的苯多羧酸和硝基苯多羧酸化合物获得良好分离。此方法简化并加快了苯多羧酸法定量黑碳和溶解态黑碳的分析过程，可满足环境样品中黑碳和溶解态黑碳的分析，促进了苯多羧酸法应用的普及。%The benzene polycarboxylic acid( BPCA)method is an important molecular marker method for black carbon and dissolved black carbon quantification while the separation and quantification of benzene polycarboxylic acids and nitro-benzene polycarboxylic acids are the key process. In order to use mass spectrometer to solve the issue of identification of benzene polycarboxylic acids and nitro-benzene polycarboxylic acids due to the lack of the standards of some of the target compounds,a liquid chromatography-mass spectrometry method was pro-posed. It made the experimental procedures easier and faster than using the gas chromatogra-phy mass spectrometry,and would promote the use of the BPCA method. A Phenomenex Syn-ergi Polar RP column was used. The digestion productions of black carbon and dissolved black carbon were gradiently eluted by the mobile phases of 0. 5%( v/v)aqueous formic acid solution and methanol with the flow rate of 0. 5 mL/min at 35 ℃. The determination
Liquid-liquid extraction columns
International Nuclear Information System (INIS)
The patent concerns liquid-liquid extraction columns in which solute transfer across the liquid-liquid interface sets up Marangoni instabilities which give rise to interfacial turbulence. The phenomenon has been observed to occur in the solvent extraction of uranium and/or plutonium from an aqueous nitric phase using tributyl phosphate with odourless kerosens. The invention provides a method of quantifying the degree of Marangoni instabilities in a column-type liquid-liquid extraction column, and determining a value for the solute free characteristic velocity parameter. The method also gives a measure of the extent to which the characteristic velocity is modified by the Marangoni instability. (U.K.)
Liquid-liquid extraction columns
Energy Technology Data Exchange (ETDEWEB)
Batey, W.; Lonie, S.J.; Thompson, P.J.; Thornton, J.D.
1987-11-11
The patent concerns liquid-liquid extraction columns in which solute transfer across the liquid-liquid interface sets up Marangoni instabilities which give rise to interfacial turbulence. The phenomenon has been observed to occur in the solvent extraction of uranium and/or plutonium from an aqueous nitric phase using tributyl phosphate with odourless kerosens. The invention provides a method of quantifying the degree of Marangoni instabilities in a column-type liquid-liquid extraction column, and determining a value for the solute free characteristic velocity parameter. The method also gives a measure of the extent to which the characteristic velocity is modified by the Marangoni instability. (U.K.).
Tawfic, Qutaiba A.
2011-01-01
Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixt...
International Nuclear Information System (INIS)
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 instance, the UK
The Impact of Liquidity Risk in Option Pricing Theory with a Supply Curve
Harr, Martin
2010-01-01
Fisher Black and Myron Scholes (Black and Scholes, 1973) presented in 1973 a valuation model for options that was intuitive and user friendly. This revolutionized the option market and made pricing an option easy. To get a sound understanding of liquidity risk we have to specify and describe liquidity (Matz and Neu, 2007, p.5). Market liquidity and funding liquidity are two kinds of liquidity. Market liquidity can be described as good when a security is easy to trade. Easy to trade is defin...
Rotating Brane World Black Holes
Modgil, Moninder Singh; Panda, Sukanta; Sengupta, Gautam
2001-01-01
A five dimensional rotating black string in a Randall-Sundrum brane world is considered. The black string intercepts the three brane in a four dimensional rotating black hole. The geodesic equations and the asymptotics in this background are discussed.
The Analysis of Saccharide in Black Garlic and its Antioxidant Activity
Mengmeng Lei; Mengying Xu; Zesheng Zhang; Min Zhang; Yunfeng Gao
2014-01-01
Black garlic was created by keeping whole ordinary garlic in a humidity controlled room at 70-80°C for 10-15 days without any artificial treatments and additives. The black garlic was extracted with 80% ethanol and concentrated to obtain black garlic ethanol extracts. The saccharides of the extracts were analyzed according to the method of Phenol Sulphate colorimetry, DNS and High Performance Liquid Chromatography (HPLC). The antioxidant capacity in vitro of the extracts was assessed by measu...
Evolution of massive black holes
Volonteri, Marta
2007-01-01
Supermassive black holes are nowadays believed to reside in most local galaxies. Accretion of gas and black hole mergers play a fundamental role in determining the two parameters defining a black hole: mass and spin. I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I'll discuss black hole formation processes that are likely to place at early cosmic epochs, and how massive black hole evolve in a hierarchical Universe...
Pyrolytic carbon coated black silicon
Shah, Ali; Stenberg, Petri; Karvonen, Lasse; Ali, Rizwan; Honkanen, Seppo; Lipsanen, Harri; Peyghambarian, N.; Kuittinen, Markku; Svirko, Yuri; Kaplas, Tommi
2016-01-01
Carbon is the most well-known black material in the history of man. Throughout the centuries, carbon has been used as a black material for paintings, camouflage, and optics. Although, the techniques to make other black surfaces have evolved and become more sophisticated with time, carbon still remains one of the best black materials. Another well-known black surface is black silicon, reflecting less than 0.5% of incident light in visible spectral range but becomes a highly reflecting surface ...
International Nuclear Information System (INIS)
A process and apparatus for recovering carbon black from hot smoke which comprises passing the smoke through a cyclone separation zone following cooling, then through aggregate filter beds and regeneration of filter beds with clean off-gas which is recycled to the carbon black reaction zone as quench
Noncommutative Singular Black Holes
International Nuclear Information System (INIS)
In this paper, applying the method of coordinate coherent states to describe a noncommutative model of Vaidya black holes leads to an exact (t - r) dependence of solution in terms of the noncommutative parameter σ. In this setup, there is no black hole remnant at long times.
Noncommutative Singular Black Holes
Hamid Mehdipour, S.
2010-11-01
In this paper, applying the method of coordinate coherent states to describe a noncommutative model of Vaidya black holes leads to an exact (t — r) dependence of solution in terms of the noncommutative parameter σ. In this setup, there is no black hole remnant at long times.
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)....
Bousso, R.; Hawking, S. W.
1997-08-01
We summarise recent work on the quantum production of black holes in the inflationary era. We describe, in simple terms, the Euclidean approach used, and the results obtained both for the pair creation rate and for the evolution of the black holes.
Andersson, N
2000-01-01
This is a chapter on Black-hole Scattering that was commissioned for an Encyclopaedia on Scattering edited by Pike and Sabatier, to be published by Academic Press. The chapter surveys wave propagation in black-hole spacetimes, diffraction effects in wave scattering, resonances, quasinormal modes and related topics.
Black Craftsmen Through History.
Myers, Robin
This report traces the evolution of the black craftsmen from ancient Egypt to the present. Special attention is given to the restricted use of black craftsmen under slavery, and the added problems they faced after being freed. Business and union discimination is described, along with recent government and private efforts to achieve equal…
Indian Academy of Sciences (India)
Koustubh Ajit Kabe
2012-09-01
In the following paper, certain black hole dynamic potentials have been developed definitively on the lines of classical thermodynamics. These potentials have been refined in view of the small differences in the equations of the laws of black hole dynamics as given by Bekenstein and those of thermodynamics. Nine fundamental black hole dynamical relations have been developed akin to the four fundamental thermodynamic relations of Maxwell. The specific heats , and , have been defined. For a black hole, these quantities are negative. The d equation has been obtained as an application of these fundamental relations. Time reversible processes observing constancy of surface gravity are considered and an equation connecting the internal energy of the black hole , the additional available energy defined as the first free energy function , and the surface gravity , has been obtained. Finally as a further application of the fundamental relations, it has been proved for a homogeneous gravitational field in black hole space times or a de Sitter black hole that $C_{\\Omega,\\Phi}-C_{J,Q}=\\kappa \\left[\\left(\\dfrac{\\partial J}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial \\Omega}{\\partial \\kappa}\\right)_{J,Q}+\\left(\\dfrac{\\partial Q}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial\\Phi}{\\partial \\kappa}\\right)_{J,Q}\\right]$. This is dubbed as the homogeneous fluid approximation in context of the black holes.
Fluctuating Black Hole Horizons
Mei, Jianwei
2013-01-01
In this paper we treat the black hole horizon as a physical boundary to the spacetime and study its dynamics following from the Gibbons-Hawking-York boundary term. Using the Kerr black hole as an example we derive an effective action that describes, in the large wave number limit, a massless Klein-Gordon field living on the average location of the boundary. Complete solutions can be found in the small rotation limit of the black hole. The formulation suggests that the boundary can be treated in the same way as any other matter contributions. In particular, the angular momentum of the boundary matches exactly with that of the black hole, suggesting an interesting possibility that all charges (including the entropy) of the black hole are carried by the boundary. Using this as input, we derive predictions on the Planck scale properties of the boundary.
Black Youth Unemployment and the Black Family.
Hoskins, Linus A.
This paper analyzes the results of a survey conducted to ascertain the attitudes of 400 employers, youth, and academic/community professionals in Los Angeles, Chicago and Washington, D.C., toward an approach to Black youth unemployment centered on the creation of jobs and training among minority businesses in selected metropolitan areas. Minority…
The Black Family in American Economy: Black Capitalism.
Ezeocha, Peter A.
Black capitalism that is well planned and run is a source of enumerable benefits to the American society in general and to blacks in particular. It generates opportunities for blacks to perform in occupations which for many years were closed to them. For hundreds of years blacks have been despised and often looked down upon on account of the fact…
On the Charter Question: Black Marxism and Black Nationalism
Stern, Mark; Hussain, Khuram
2015-01-01
This article brings two black intellectual traditions to bear on the question of charter schools: black Marxism and black nationalism. The authors examine the theoretical and rhetorical devices used to talk about charters schools by focusing on how notions of "black liberation" are deployed by the charter movement, and to what end. The…
Directory of Open Access Journals (Sweden)
Qutaiba A. Tawfic
2011-01-01
Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.
ULTRAMASSIVE BLACK HOLE COALESCENCE
International Nuclear Information System (INIS)
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
LIQUID DYES'CHARACTERISTICS IN DYEING WASTE PAPER PULP AND THEIR APPLICATION
Institute of Scientific and Technical Information of China (English)
Xiaoping Wang; gang Chen; Aimin Tang; Hongwei Zhang
2004-01-01
In this paper, some liquid dyes were used to dye the waste paper pulp (OCC pulp and waste cement sack paper pulp), and their dyeing characteristics were analyzed, The liquid dyes include liquid basic yellow, liquid basic blue, liquid basic red, liquid basic orange, liquid basic brown and liquid direct black. We found that, each dye had its own dyeing characteristic while dyeing the waste paper pulp.Generally different types of liquid dyes were combined to dye the waste paper pulp, which the adding process must be noticed. We also observed that a black pigment could be applied together with said liquid dyes to dye or adjust the color of the bottom sheet for the fireproof board. We could also achieve the same dyeing result through different combinations of different dyes.
LIQUID DYES＇CHARACTERISTICS IN DYEING WASTE PAPER PULP AND THEIR APPLICATION
Institute of Scientific and Technical Information of China (English)
XiaopingWang; gangChen; AiminTang; HongweiZhang
2004-01-01
In this paper, some liquid dyes were used to dye the waste paper pulp (OCC pulp and waste cement sack paper pulp), and their dyeing characteristics were analyzed, The liquid dyes include liquid basic yellow, liquid basic blue, liquid basic red, liquid basic orange, liquid basic brown and liquid direct black. We found that, each dye had its own dyeing characteristic while dyeing the waste paper pulp. Generally different types of liquid dyes were combined to dye the waste paper pulp, which the adding process must be noticed. We also observed that a black pigment could be applied together withsaid liquid dyes to dye or adjust the color of the bottom sheet for the fireproof board. We could also achieve the same dyeing result through different combinations of different dyes.
Noncommutative Solitonic Black Hole
Chang-Young, Ee; Lee, Daeho; Lee, Youngone
2012-01-01
We investigate solitonic black hole solutions in three dimensional noncommutative spacetime. We do this in gravity with negative cosmological constant coupled to a scalar field using the Moyal product expanded up to first order in the noncommutativity parameter in the two noncommutative spatial directions. By numerical simulation we look for black hole solutions by increasing the non- commutativity parameter value starting from regular solutions with vanishing noncommutativity. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value.
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
Kuchiev, M Yu
2003-01-01
Black holes are presumed to have an ideal ability to absorb and keep matter. Whatever comes close to the event horizon, a boundary separating the inside region of a black hole from the outside world, inevitably goes in and remains inside forever. This work shows, however, that quantum corrections make possible a surprising process, reflection: a particle can bounce back from the event horizon. For low energy particles this process is efficient, black holes behave not as holes, but as mirrors, which changes our perception of their physical nature. Possible ways for observations of the reflection and its relation to the Hawking radiation process are outlined.
International Nuclear Information System (INIS)
In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn
Energy Technology Data Exchange (ETDEWEB)
Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kunz, Jutta [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Yazadjiev, Stoytcho [Department of Theoretical Physics, Faculty of Physics, Sofia University, Sofia 1164 (Bulgaria)
2015-05-11
In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
Kleihaus, Burkhard; Yazadjiev, Stoytcho
2015-01-01
In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
On Noncommutative Black Holes Thermodynamics
Faizal, Mir; Ulhoa, S C
2015-01-01
In this paper, we will analyze noncommutative deformation of the Schwarzschild black holes and Kerr black holes. We will perform our analysis by relating the commutative and the noncommutative metrics using an Moyal product. We will also analyze the thermodynamics of these noncommutative black hole solutions. We will explicitly derive expression for the corrected entropy and temperature of these black hole solutions.
The Thermodynamics of Black Holes
Directory of Open Access Journals (Sweden)
Wald Robert M.
2001-01-01
Full Text Available We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.
The Price of "Black Dominance."
Hoberman, John
2000-01-01
Discusses the harmful effects of stereotyping black males as athletes, noting that over-identification with athletes and the world of physical performance limits black children's development by discouraging academic achievement. Examines the negative influence of mass media focus on black athletes, rappers, and stylized ghetto blackness. Discusses…
The Thermodynamics of Black Holes
Wald Robert M.
1999-01-01
We review the present status of black hole thermodynamics. Our review includes discussion of classical black hole thermodynamics, Hawking radiation from black holes, the generalized second law, and the issue of entropy bounds. A brief survey also is given of approaches to the calculation of black hole entropy. We conclude with a discussion of some unresolved open issues.
Black Writers' Views of America.
Ladner, Joyce
1979-01-01
Black literature of the 1960s reflected protest and an affirmation of Black power and Black consciousness. The 1970s have produced a counterwave in which Blacks, in order to achieve literary and financial recognition, have begun to focus less on race and social criticism and more on conservative and narcissistic themes. (Author/EB)
Topics in black hole evaporation
International Nuclear Information System (INIS)
Two major aspects of particle creation by gravitational fields of black holes are studied: the neutrino emission from rotating black holes; and interactions between scalar particles emitted by a black hole. Neutrino emission is investigated under three topics: The asymmetry of the angular dependence of neutrino emission from rotating black holes; the production of a local matter excess by rotating black holes in a baryon symmetric universe; and cosmological magnetic field generation by neutrinos from evaporating black holes. Finally the author studies the effects of interactions on the black hole evaporation process
Black Holes in Higher Dimensions
International Nuclear Information System (INIS)
In four space-time dimensions black holes of Einstein-Maxwell theory satisfy a number of theorems. In more than four space-time dimensions, however, some of the properties of black holes can change. In particular, uniqueness of black holes no longer holds. In five and more dimensions black rings arise. Thus in a certain region of the phase diagram there are three black objects with the same global charges present. Here we discuss properties of higher-dimensional vacuum and charged black holes, which possess a spherical horizon topology, and of vacuum and charged black rings, which have a ringlike horizon topology
Phase transitions of black holes in massive gravity
Fernando, Sharmanthie
2016-05-01
In this paper, we have studied thermodynamics of a black hole in massive gravity in the canonical ensemble. The massive gravity theory in consideration here has a massive graviton due to Lorentz symmetry breaking. The black hole studied here has a scalar charge due to the massive graviton and is asymptotically anti-de Sitter (AdS). We have computed various thermodynamical quantities such as temperature, specific heat and free energy. Both the local and global stability of the black hole are studied by observing the behavior of the specific heat and the free energy. We have observed that there is a first-order phase transition between small (SBH) and large black hole (LBH) for a certain range of the scalar charge. This phase transition is similar to the liquid/gas phase transition at constant temperature for a van der Waals fluid. The coexistence curves for the SBH and LBH branches are also discussed in detail.
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)
... dling boxes, firewood, lumber, and rocks, etc. The black widow is commonly found in the following places: • Outdoors - woodpiles, rubble piles, under stones, in hol- low stumps, and in rodent burrows, privies, sheds ...
International Nuclear Information System (INIS)
Shipboard, high volume air particulate samples were collected from the Black Sea atmosphere and analyzed by instrumental neutron activation analysis, atomic absorption spectrophotometry and ion chromatography for about 40 elements and ions. Concentrations of elements in the eastern and western parts of the Black Sea are different at the 95% confidence level, with lower concentrations in the eastern Black Sea. Back-trajectories and concentrations of elements in trajectory groups show that Europe accounts for more than 70% of the anthropogenic elements in the atmosphere. The average sulfate concentration was 7 μg/m3, which is comparable with rural sulfate levels in western Europe. Fluxes of elements from the atmosphere to the Black Sea are in good agreement with the results of similar flux calculations for other regions
Black Friday = Broget Branding?
DEFF Research Database (Denmark)
Hansen, Heidi
2015-01-01
Black Friday er et godt eksempel på, hvordan ikke kun produktbrands og corporate brands rejser på tværs af landegrænser, men også traditioner som Halloween, Valentines Day og i dette tilfælde den ultimative tilbuds-fredag, som i USA går under navnet Black Friday. Men hvad er Black Friday i Danmark......? Essensen ved Black Friday er lave priser, og det er der ved første øjekast ikke mange brandingmuligheder forbundet ved, hvis man forstår branding som en måde at skabe ekstra værdi omkring sit produkt eller sin virksomhed. Som brand bliver man dog alligevel nødt til at forholde sig til konceptet, da det er...
International Nuclear Information System (INIS)
In this review we shall concentrate on the application of the concept of black hole to different areas in astrophysics. Models in which this idea is involved are connected with basically two areas in astrophysics: a) The death of massive stars due to gravitational collapse. This process would lead to the formation of black holes with stellar masses (10-20 M sun). The detection of these kind of - objects is in principle possible, by means of studying the so-called X-ray binary system. b) Active nuclei of galaxies, including quasars as an extreme case. In this case, the best model available to explain the generation of the enormous amounts of energy observed as well as several other properties, is accretion into a supermassive black hole (106-1010 M sun) in the center. The problem of the origin of such black holes is related to cosmology. (author)
DEFF Research Database (Denmark)
Malinova, Katya; Park, Andreas
2015-01-01
breakdown of trading fees between liquidity demanders and suppliers matters. Posted quotes adjust after the change in fee composition, but the transaction costs for liquidity demanders remain unaffected once fees are taken into account. However, as posted bid-ask spreads decline, traders (particularly...... retail) use aggressive orders more frequently, and adverse selection costs decrease....
Cosmic censorship inside black holes
Thorlacius, L
2006-01-01
A simple argument is given that a traversable Cauchy horizon inside a black hole is incompatible with unitary black hole evolution. The argument assumes the validity of black hole complementarity and applies to a generic black hole carrying angular momentum and/or charge. In the second part of the paper we review recent work on the semiclassical geometry of two-dimensional charged black holes.
Bekenstein, Jacob D.
1997-01-01
In some respects the black hole plays the same role in gravitation that the atom played in the nascent quantum mechanics. This analogy suggests that black hole mass $M$ might have a discrete spectrum. I review the physical arguments for the expectation that black hole horizon area eigenvalues are uniformly spaced, or equivalently, that the spacing between stationary black hole mass levels behaves like 1/M. This sort of spectrum has also emerged in a variety of formal approaches to black hole ...
Stornaiolo, Cosimo
2001-01-01
In this paper we propose a model for the formation of the cosmological voids. We show that cosmological voids can form directly after the collapse of extremely large wavelength perturbations into low-density black holes or cosmological black holes (CBH). Consequently the voids are formed by the comoving expansion of the matter that surrounds the collapsed perturbation. It follows that the universe evolves, in first approximation, according to the Einstein-Straus cosmological model. We discuss...
International Nuclear Information System (INIS)
No particle theory can be complete without gravity. Einstein's theory of gravity is of the Euler-Lagrange form, but standard quantization procedure fails. In quantum gravity the higher order interactions have a dimensionality different form the fundamental ones, because Newton's constant G has dimensions and the renormalization procedure fails. Another problem with quantum gravity is even more mysterious. Suppose that we had regularized the gravitational forces at the small distance end in the way that the weak intermediate vector boson regularized the fundamental 4-fermion interaction vertex of the weak interactions. Then what we discover is that the gravitational forces are unstable. Given sufficiently large amount of matter, it can collapse under its own weight. Classical general relativity tells us what will happen: a black hole is formed. But how is this formulated in quantum theory. S. Hawking observed that when a field theory is quantized in the background metric of a black hole, the black hole actually emits particles in a completely random thermal way. Apparently black holes are just another form of matter unstable against Hawking decay. Unfortunately this picture cannot be complete. The problem is that the quantum version of black holes has infinite phase space, and other symptoms of a run-away solution. Black holes are the heaviest and most compact forms of matter that can be imagined. A complete particle theory can have nothing but a spectrum of black-hole like objects at it high-energy end. This is why it is believed that a resolution of the black hole problem will in time disclose the complete small-distance structure of our world. 6 references
Thermal corpuscular black holes
Casadio, Roberto; Giugno, Andrea; Orlandi, Alessio
2015-01-01
We study the corpuscular model of an evaporating black hole consisting of a specific quantum state for a large number $N$ of self-confined bosons. The single-particle spectrum contains a discrete ground state of energy $m$ (corresponding to toy gravitons forming the black hole), and a gapless continuous spectrum (to accommodate for the Hawking radiation with energy $\\omega>m$). Each constituent is in a superposition of the ground state and a Planckian distribution at the expected Hawking temp...
Gurvits, Grigoriy E; Tan, Amy
2014-01-01
Black hairy tongue (BHT) is a benign medical condition characterized by elongated filiform lingual papillae with typical carpet-like appearance of the dorsum of the tongue. Its prevalence varies geographically, typically ranging from 0.6% to 11.3%. Known predisposing factors include smoking, excessive coffee/black tea consumption, poor oral hygiene, trigeminal neuralgia, general debilitation, xerostomia, and medication use. Clinical presentation varies but is typically asymptomatic, although ...
Bremond, Nicolas; Bibette, Jérôme
2010-01-01
This fluid dynamics video reports how to form liquid core capsules having a thin hydrogel elastic membrane named liquid pearls. These fish-egg like structures are initially made of a millimetric liquid drop, aqueous or not, coated with an aqueous liquid film containing sodium alginate that gels once the double drop enters a calcium chloride bath. The creation of such pearls with micrometer thick membrane requires to suppress mixing until gelling takes place. Here, we show that superimposing a two dimensional surfactant precipitation at the interface confers a transient rigidity that can damp the shear induced instability at impact. Based on this, pearls containing almost any type of liquids can be created. The video focuses on the dynamics of the entry of the compound drop into the gelling bath.
Babichev, Eugeny; Charmousis, Christos; Hassaine, Mokhtar
2015-05-01
We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.
Black hole critical phenomena without black holes
Indian Academy of Sciences (India)
Steven L Liebling
2000-10-01
Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I brieﬂy review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.
Orientation of liquid crystalline materials by using carbon nanotubes
Directory of Open Access Journals (Sweden)
Kamanina N.V.
2011-01-01
Full Text Available The solution of some problems, where the initial black field is necessary for the regime of light transmission through the electrooptical organic nematic liquid crystal structures has been considered via a homeotropic alignment of liquid crystal molecules on the substrate covered by carbon nanotubes. The results of this investigation can be used to develop optical elements for displays with vertical orientations of nematic liquid crystal molecules (for example, for MVA-display technology.
Formation mechanism of diamond nanocrystal from catalysed carbon black
International Nuclear Information System (INIS)
Recently, our group has synthesized nanocrystal n-diamond and diamond-like carbon (DLC) from catalysed carbon black. Based on the results of XRD, TGA and DTA, a formation mechanism has been proposed to explain the phase transformation from carbon black to diamond nanocrystal. With the increase of temperature and hence the carbon diffusion in iron, the phase sequence is from Fe(OH)3 into Fe2O3, α-Fe, γ-Fe, then liquid iron. When the carbon in the liquid iron is saturated, DLC or graphite separates out of the liquid iron. With decrease of temperature, the carbon in γ-Fe is separated out, and n-diamond nuclei form and grow
Formation mechanism of diamond nanocrystal from catalysed carbon black
Wen, Bin; Li, Tingju; Dong, Chuang; Zhang, Xingguo; Yao, Shan; Cao, Zhiqiang; Wang, Dehe; Ji, Shouhua; Jin, Junze
2004-10-01
Recently, our group has synthesized nanocrystal n-diamond and diamond-like carbon (DLC) from catalysed carbon black. Based on the results of XRD, TGA and DTA, a formation mechanism has been proposed to explain the phase transformation from carbon black to diamond nanocrystal. With the increase of temperature and hence the carbon diffusion in iron, the phase sequence is from Fe(OH)3 into Fe2O3, agr-Fe, ggr-Fe, then liquid iron. When the carbon in the liquid iron is saturated, DLC or graphite separates out of the liquid iron. With decrease of temperature, the carbon in ggr-Fe is separated out, and n-diamond nuclei form and grow.
Formation mechanism of diamond nanocrystal from catalysed carbon black
Energy Technology Data Exchange (ETDEWEB)
Wen Bin [Department of Materials Engineering, Dalian University of Technology, Dalian 116023 (China); Li Tingju [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116023 (China); Dong Chuang [Department of Materials Engineering, Dalian University of Technology, Dalian 116023 (China); Zhang Xingguo [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116023 (China); Yao Shan [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116023 (China); Cao Zhiqiang [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116023 (China); Wang Dehe [Department of Materials Engineering, Dalian University of Technology, Dalian 116023 (China); Ji Shouhua [Department of Materials Engineering, Dalian University of Technology, Dalian 116023 (China); Jin Junze [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116023 (China)
2004-10-06
Recently, our group has synthesized nanocrystal n-diamond and diamond-like carbon (DLC) from catalysed carbon black. Based on the results of XRD, TGA and DTA, a formation mechanism has been proposed to explain the phase transformation from carbon black to diamond nanocrystal. With the increase of temperature and hence the carbon diffusion in iron, the phase sequence is from Fe(OH){sub 3} into Fe{sub 2}O{sub 3}, {alpha}-Fe, {gamma}-Fe, then liquid iron. When the carbon in the liquid iron is saturated, DLC or graphite separates out of the liquid iron. With decrease of temperature, the carbon in {gamma}-Fe is separated out, and n-diamond nuclei form and grow.
DEFF Research Database (Denmark)
Pokutta, Sebastian; Schmaltz, Christian
2011-01-01
Large banking groups face the question of how to optimally allocate and generate liquidity: in a central liquidity hub or in many decentralized branches. We translate this question into a facility location problem under uncertainty. We show that volatility is the key driver behind (de-)centraliza......Large banking groups face the question of how to optimally allocate and generate liquidity: in a central liquidity hub or in many decentralized branches. We translate this question into a facility location problem under uncertainty. We show that volatility is the key driver behind (de......-)centralization. We provide an analytical solution for the 2-branch model and show that a liquidity center can be interpreted as an option on immediate liquidity. Therefore, its value can be interpreted as the price of information, i.e., the price of knowing the exact demand. Furthermore, we derive the threshold...... above which it is advantageous to open a liquidity center and show that it is a function of the volatility and the characteristic of the bank network. Finally, we discuss the n-branch model for real-world banking groups (10-60 branches) and show that it can be solved with high granularity (100 scenarios...
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
Hawking, S. W.
1996-03-01
One would expect spacetime to have a foamlike structure on the Planck scale with a very high topology. If spacetime is simply connected (which is assumed in this paper), the nontrivial homology occurs in dimension two, and spacetime can be regarded as being essentially the topological sum of S2×S2 and K3 bubbles. Comparison with the instantons for pair creation of black holes shows that the S2×S2 bubbles can be interpreted as closed loops of virtual black holes. It is shown that scattering in such topological fluctuations leads to loss of quantum coherence, or in other words, to a superscattering matrix S/ that does not factorize into an S matrix and its adjoint. This loss of quantum coherence is very small at low energies for everything except scalar fields, leading to the prediction that we may never observe the Higgs particle. Another possible observational consequence may be that the θ angle of QCD is zero without having to invoke the problematical existence of a light axion. The picture of virtual black holes given here also suggests that macroscopic black holes will evaporate down to the Planck size and then disappear in the sea of virtual black holes.
Babichev, Eugeny; Hassaine, Mokhtar
2015-01-01
We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematic...
Cai, Rong-Gen; Wu, Yue-Liang; Zhang, Yun-Long
2016-01-01
In this paper we investigate the $(2+1)$-dimensional topological non-Fermi liquid in strongly correlated electron system, which has a holographic dual description by Einstein gravity in $(3+1)$-dimensional anti-de Sitter (AdS) space-time. In a dyonic Reissner-Nordstrom black hole background, we consider a Dirac fermion coupled to the background $U(1)$ gauge theory and an intrinsic chiral gauge field $b_M$ induced by chiral anomaly. UV retarded Green's function of the charged fermion in the UV boundary from AdS$_4$ gravity is calculated, by imposing in-falling wave condition at the horizon. We also obtain IR correlation function of the charged fermion at the IR boundary arising from the near horizon geometry of the topological black hole with index $k=0,\\pm 1$. By using the UV retarded Green's function and IR correlation function, we analyze the low frequency behavior of the topological non-Fermi liquid at zero and finite temperatures, especially the relevant non-Fermi liquid behavior near the quantum critical...
Liquid-liquid contractor columns
International Nuclear Information System (INIS)
A liquid-liquid contactor column has a solvent input and an aqueous phase input. Lighter phase liquid is discharged and heavier phase is moved by an air lift to a receiver. The air supply line to the air lift includes valve and a pressure sensing transducer senses pressure in line and sends electric signals to signal processing unit which may for example close down operation of the column, or effect other changes to maintain operating characteristics of the column. The column could be pulsed by means which also send signals to unit, and could deliver to an external settler. (author)
Belov, N. P.; Lapshov, S. N.; Mayorov, E. E.; Sherstobitova, A. S.; Yaskov, A. D.
2012-07-01
Measurements of the refractive index, its temperature dependence, and the optical transmission of black liquors produced during sulfate pulping are reported for soluble solid residue concentrations up to k ≅ 60 %. The design features of a commercial refractometer for monitoring the concentration of black liquor are examined briefly. A procedure is proposed for laboratory calibration of commercial sensors that employs black liquor solutions in highly refractive organic liquids as reference samples.
Institute of Scientific and Technical Information of China (English)
ZHAO Liu
2007-01-01
Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzed by use of the Parikh-Wilczek tunneling method. To get the correct tunneling amplitude and emission rate, we adopt and develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitutes a unified approach to the tunneling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agrees exactly with the results obtained via the classical surface gravity method and the quasi-local formalism.
Noncommutative black hole thermodynamics
International Nuclear Information System (INIS)
We give a general derivation, for any static spherically symmetric metric, of the relation Th=(K/2π) connecting the black hole temperature (Th) with the surface gravity (K), following the tunneling interpretation of Hawking radiation. This derivation is valid even beyond the semi-classical regime, i.e. when quantum effects are not negligible. The formalism is then applied to a spherically symmetric, stationary noncommutative Schwarzschild space-time. The effects of backreaction are also included. For such a black hole the Hawking temperature is computed in a closed form. A graphical analysis reveals interesting features regarding the variation of the Hawking temperature (including corrections due to noncommutativity and backreaction) with the small radius of the black hole. The entropy and tunneling rate valid for the leading order in the noncommutative parameter are calculated. We also show that the noncommutative Bekenstein-Hawking area law has the same functional form as the usual one
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. PMID:25768746
International Nuclear Information System (INIS)
General consensus on the nature of the degrees of freedom responsible for the black hole entropy remains elusive despite decades of effort dedicated to the problem. Different approaches to quantum gravity disagree in their description of the microstates and, more significantly, in the statistics used to count them. In some approaches (string theory, AdS/CFT) the elementary degrees of freedom are indistinguishable, whereas they must be treated as distinguishable in other approaches to quantum gravity (eg., LQG) in order to recover the Bekenstein-Hawking area-entropy law. However, different statistics will imply different behaviors of the black hole outside the thermodynamic limit. We illustrate this point by quantizing the Bañados-Teitelboim-Zanelli (BTZ) black hole, for which we argue that Bose condensation will occur leading to a cold, stable remnant
Vaz, Cenalo; Wijewardhana, L. C. R.
2013-12-01
General consensus on the nature of the degrees of freedom responsible for the black hole entropy remains elusive despite decades of effort dedicated to the problem. Different approaches to quantum gravity disagree in their description of the microstates and, more significantly, in the statistics used to count them. In some approaches (string theory, AdS/CFT) the elementary degrees of freedom are indistinguishable, whereas they must be treated as distinguishable in other approaches to quantum gravity (eg., LQG) in order to recover the Bekenstein-Hawking area-entropy law. However, different statistics will imply different behaviors of the black hole outside the thermodynamic limit. We illustrate this point by quantizing the Bañados-Teitelboim-Zanelli (BTZ) black hole, for which we argue that Bose condensation will occur leading to a "cold", stable remnant.
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
Fischetti, Sebastian
2013-01-01
We construct the gravitational dual, in the Unruh state, of the "jammed" phase of a CFT at strong coupling and infinite N on a fixed five-dimensional rotating Myers-Perry black hole with equal angular momenta. When the angular momenta are all zero, the solution corresponds to the five-dimensional generalization of the solution first studied by Figueras, Lucietti, and Wiseman. In the extremal limit, when the angular momenta of the Myers-Perry black hole are maximum, the Unruh, Boulware and Hartle-Hawking states degenerate. We give a detailed analysis of the corresponding holographic stress energy tensor for all values of the angular momenta, finding it to be regular at the horizon in all cases. We compare our results with existent literature on thermal states of free field theories on black hole backgrounds.
Yang, Huan; Lehner, Luis
2014-01-01
We show that rapidly-spinning black holes can display turbulent gravitational behavior which is mediated by a new type of parametric instability. This instability transfers energy from higher temporal and azimuthal spatial frequencies to lower frequencies--- a phenomenon reminiscent of the inverse energy cascade displayed by 2+1-dimensional turbulent fluids. Our finding reveals a path towards gravitational turbulence for perturbations of rapidly-spinning black holes, and provides the first evidence for gravitational turbulence in an asymptotically flat spacetime. Interestingly, this finding predicts observable gravitational wave signatures from such phenomena in black hole binaries with high spins and gives a gravitational description of turbulence relevant to the fluid-gravity duality.
Yang, Huan; Zimmerman, Aaron; Lehner, Luis
2015-02-01
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.
International Nuclear Information System (INIS)
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 NB=eΦ∞/(πc(ℎ/2π)), where Φ∞≅2π2BNSRNS3/(PNSc) 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.
Lyutikov, Maxim; McKinney, Jonathan C.
2011-10-01
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 NB=eΦ∞/(πcℏ), where Φ∞≈2π2BNSRNS3/(PNSc) 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.
International Nuclear Information System (INIS)
The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome ‘remnants’. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in the bound state. The interior of the black hole gets completely altered to a ‘fuzzball’ structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates together with ideas about entangled states leads to a natural set of conjectures on many long-standing questions in gravity: the significance of Rindler and de Sitter entropies, the notion of black hole complementarity, and the fate of an observer falling into a black hole. - Highlights: ► The information paradox is a serious problem. ► To solve it we need to find ‘hair’ on black holes. ► In string theory we find ‘hair’ by the fuzzball construction. ► Fuzzballs help to resolve many other issues in gravity.
Exact solutions of higher dimensional black holes
Tomizawa, Shinya
2011-01-01
We review exact solutions of black holes in higher dimensions, focusing on asymptotically flat black hole solutions and Kaluza-Klein type black hole solutions. We also summarize some properties which such black hole solutions reveal.
Schelz, Zsuzsanna; Molnar, Joseph; Fogliano, Vincenzo; Ferracane, Rosalia; Pernice, Rita; 白瀧, 義明; 本橋, 登
2006-01-01
In earlier experiments, the MDR (multidrug resistance)-reversal activities of Anastasia Black (Russian black sweet pepper) extracts had been analysed. Recently, the most effective MDR reversing extracts and fractions have been separated by HPLC (high-performance liquid chromatography, for carotenoids) and LC-MS-MS (HPLC combined with mass spectrometry, for phenolic compounds) methods. As a result of the analytical studies, the following flavonoids had been identified: feruloyl glucopyranoside...
Energy Technology Data Exchange (ETDEWEB)
Lisin, M.A. [Koon-Hall-Adrian Metallurgical, Portland, OR (United States)
1996-11-01
Black light photography of fluorescent penetrant and wet fluorescent magnetic particle indications can yield spectacular and useful results. The technique provides a lasting record of a flaw`s severity and location, as well as its physical relation to other components and important features. The procedures are easily learned and do not require sophisticated apparatus. In fact, equipment costs can often be justified on the basis of a single application. Using the techniques described in this article, black light photography can be a cost-effective, informative NDT tool.
Noncommutative solitonic black hole
International Nuclear Information System (INIS)
We investigate solitonic black hole solutions in three-dimensional noncommutative spacetime. We do this in gravity with a negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value. (paper)
Noncommutative solitonic black hole
Chang-Young, Ee; Kimm, Kyoungtae; Lee, Daeho; Lee, Youngone
2012-05-01
We investigate solitonic black hole solutions in three-dimensional noncommutative spacetime. We do this in gravity with a negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find that even a regular soliton solution in the commutative case becomes a black hole solution when the noncommutativity parameter reaches a certain value.
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 ...
Aarseth, Sverre J
2007-01-01
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.
Characterizing Black Hole Mergers
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.
Energy Technology Data Exchange (ETDEWEB)
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.
International Nuclear Information System (INIS)
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
Visser, M
1999-01-01
Acoustic propagation in a moving fluid provides a conceptually clean and powerful analogy for understanding black hole physics. As a teaching tool, the analogy is useful for introducing students to both General Relativity and fluid mechanics. As a research tool, the analogy helps clarify what aspects of the physics are kinematics and what aspects are dynamics. In particular, Hawking radiation is a purely kinematical effect, whereas black hole entropy is intrinsically dynamical. Finally, I discuss the fact that with present technology acoustic Hawking radiation is almost experimentally testable.
Good, Michael R R
2014-01-01
A $(3+1)$-dimensional asymptotically flat Kerr black hole angular speed $\\Omega_+$ can be used to define an effective spring constant, $k=m\\Omega_+^2$. Its maximum value is the Schwarzschild surface gravity, $k = \\kappa $, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\\pi T = \\kappa - k$. 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.
Directory of Open Access Journals (Sweden)
Rafael Martínez-Girón
2013-01-01
Full Text Available Black-pigmented sputum, also called "melanoptysis," is a symptom that may be observed in certain pathologies such us coal workers′ pneumoconiosis (anthracosis. The cavitation and liquefaction of a fibrosed mass by an infectious process (tuberculosis, infections by anaerobes, etc. or by ischemic necrosis may cause expectoration of a blackish secretion. We report the case of a patient with labor precedents as a coal worker, from whom abundant black sputum was obtained in the course of an incidental expectoration. Cyto-histological findings are shown and a differential diagnosis is established.
Horndeski black hole geodesics
Tretyakova, D A
2016-01-01
We examine geodesics for the scalar-tensor black holes in the Horndeski-Galileon framework. Our analysis shows that first kind relativistic orbits may not be present within some model parameters range. This is a highly pathological behavior contradicting to the black hole accretion and Solar System observations. We also present a new (although very similar to those previously known) solution, which contains the orbits we expect from a compact object, admits regular scalar field at the horizon and and can fit into the known stability criteria.
Good, Michael R R
2016-01-01
A black mirror is an accelerated boundary that produces particles in an exact correspondence to an evaporating black hole. We investigate the spectral dynamics of the particle creation during the formation process.
Horowitz, Gary T.; Maldacena, Juan
2003-01-01
We propose that in quantum gravity one needs to impose a final state boundary condition at black hole singularities. This resolves the apparent contradiction between string theory and semiclassical arguments over whether black hole evaporation is unitary.
Quantum aspects of black holes
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.
Conquering the Black Girl Blues.
Jones, Lani Valencia; Guy-Sheftall, Beverly
2015-10-01
An examination of the literature on epidemiology, etiology, and use of services for this population reveals an insufficient application of culturally congruent approaches to intervening with black women. An exploration of the social work practice literature and other relevant fields indicate that black feminist perspectives offer the opportunity to gain a clearer understanding of the intersection and influence of oppression among black women struggling with psychiatric issues and provide a useful framework for mental health practice with this population. This article discusses the evolving black feminist thought and summarizes the scholarship on black women's mental health services needs and utilization issues. The article includes a discussion of black feminisms as an emerging mental health perspective, arguing that black feminist perspectives in therapy provide an ideal framework for services that are responsive to the values and health needs of black women. The article concludes with a case vignette that illustrates some of its points. PMID:26489355
Black Hole Evaporation. A Survey
Benachenhou, Farid
1994-01-01
This thesis is a review of black hole evaporation with emphasis on recent results obtained for two dimensional black holes. First, the geometry of the most general stationary black hole in four dimensions is described and some classical quantities are defined. Then, a derivation of the spectrum of the radiation emitted during the evaporation is presented. In section four, a two dimensional model which has black hole solutions is introduced, the so-called CGHS model. These two dimensional blac...
Towards noncommutative quantum black holes
International Nuclear Information System (INIS)
In this paper we study noncommutative black holes. We use 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 the Hawking's temperature and entropy for the noncommutative Schwarzschild black hole
Towards Noncommutative Quantum Black Holes
Lopez-Dominguez, J. C.; Obregon, O.; Ramirez, C.; Sabido, M.
2006-01-01
In this paper we study noncommutative black holes. We use 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 the Hawking's temperature and entropy for the noncommutative Schwarzschild black hole.
Chamblin, A; Reall, H S
2000-01-01
Gravitational collapse of matter trapped on a brane will produce a black hole on the brane. We discuss such black holes in the models of Randall and Sundrum where our universe is viewed as a domain wall in five dimensional anti-de Sitter space. We present evidence that a non-rotating uncharged black hole on the domain wall is described by a ``black cigar'' solution in five dimensions.
Chamblin, A.; Hawking, S. W.; Reall, H. S.
2000-03-01
Gravitational collapse of matter trapped on a brane will produce a black hole on the brane. We discuss such black holes in the models of Randall and Sundrum where our universe is viewed as a domain wall in five-dimensional anti-de Sitter space. We present evidence that a non-rotating uncharged black hole on the domain wall is described by a ``black cigar'' solution in five dimensions.
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.
Black Hole: The Interior Spacetime
Ong, Yen Chin
2016-01-01
The information loss paradox is often discussed from the perspective of the observers who stay outside of a black hole. However, the interior spacetime of a black hole can be rather nontrivial. We discuss the open problems regarding the volume of a black hole, and whether it plays any role in information storage. We also emphasize the importance of resolving the black hole singularity, if one were to resolve the information loss paradox.
Acoustic black holes: recent developments in the theory and applications.
Krylov, Victor
2014-08-01
Acoustic black holes are relatively new physical objects that have been introduced and investigated mainly during the last decade. They can absorb almost 100% of the incident wave energy, and this makes them very attractive for such traditional engineering applications as vibration damping in different engineering structures and sound absorption in gases and liquids. They also could be useful for some ultrasonic devices using Lamb wave propagation to provide anechoic termination for such waves. So far, acoustic black holes have been investigated mainly for flexural waves in thin plates, for which the required gradual changes in local wave velocity with distance can be easily achieved by changing the plates' local thickness. The present paper provides a brief review of the theory of acoustic black holes, including their comparison with optic black holes introduced about five years ago. Review is also given of the recent experimental work carried out at Loughborough University on damping structural vibrations using the acoustic black hole effect. This is followed by the discussion on potential applications of the acoustic black hole effect for sound absorption in air. PMID:25073137
1990-01-01
Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.
Aussillous, Pascale; Quéré, David
2001-06-01
The transport of a small amount of liquid on a solid is not a simple process, owing to the nature of the contact between the two phases. Setting a liquid droplet in motion requires non-negligible forces (because the contact-angle hysteresis generates a force opposing the motion), and often results in the deposition of liquid behind the drop. Different methods of levitation-electrostatic, electromagnetic, acoustic, or even simpler aerodynamic techniques-have been proposed to avoid this wetting problem, but all have proved to be rather cumbersome. Here we propose a simple alternative, which consists of encapsulating an aqueous liquid droplet with a hydrophobic powder. The resulting `liquid marbles' are found to behave like a soft solid, and show dramatically reduced adhesion to a solid surface. As a result, motion can be generated using gravitational, electrical and magnetic fields. Moreover, because the viscous friction associated with motion is very small, we can achieve quick displacements of the droplets without any leaks. All of these features are of potential benefit in microfluidic applications, and also permit the study of a drop in a non-wetting situation-an issue of renewed interest following the recent achievement of super-hydrophobic substrates.
Blacks and the Women's Movement.
Loiacono, Stephanie
1989-01-01
Although Black female leaders were influential in creating the modern women's movement, feminism has evolved differently for both Black and White women. Suggests that, although Black women have struggled largely against racial and economic inequalities, women of all colors and backgrounds should embrace their diversity and unite to oppose racism…
The Strengths of Black Families.
Hill, Robert B.
This report identifies and analyzes five strengths of black families: adaptability roles, strong kinship bonds, strong work orientation, strong religious orientation, and achievement orientation. These five characteristics have been functional for the survival, advancement, and stability of black families. Most discussions of black families tend…
Black carbon in marine sediments
Middelburg, J.J.; Nieuwenhuize, J.; Van Breugel, P.
1999-01-01
Concentrations of black carbon were determined for a number of marine sediments. A comparison of black carbon based on thermal oxidation and hot concentrated nitric acid pretreatments revealed that the latter significantly overestimates combustion derived carbon phases. Black carbon accounts for abo
Warped products and black holes
International Nuclear Information System (INIS)
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
Black Progress: Convergence or Cleavage?
Hill, Robert B.
1982-01-01
The popular view of a permanent Black underclass falling farther behind an expanding Black middle class is disputed by empirical evidence that the underclass is experiencing upward mobility. The discrepancy stems from social scientists' overreliance on cross-sectional data rather than longitudinal data in analyzing economic change among Blacks.…
Warped products and black holes
Hong, S T
2005-01-01
We apply the warped product spacetime scheme to the Banados-Teitelboim-Zanelli black holes and the Reissner-Nordstr\\"om-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.
Black silicon with black bus-bar strings
DEFF Research Database (Denmark)
Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io;
2016-01-01
We present the combination of black silicon texturing and blackened bus-bar strings as a potential method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon was realized by mask-less reactive ion etching resulting in total, average reflectance...... below 0.5% across a 156x156 mm2 silicon wafer. Black bus-bars were realized by oxidized copper resulting in reflectance below 3% in the entire visible wavelength range. The combination of these two technologies may result in aesthetic, all-black panels based on conventional, front-contacted solar cells...
Baskin, Wade; Runes, Richard N.
This dictionary is an encyclopedic survey of the cultural background and development of the black American, covering the basic issues, events, contributions and biographies germane to the subject. The author-compiler is Chairman of Classical Languages Department at Southeastern State College, Durant, Oklahoma. Richard Runes is practicing law as a…
Noldon, Carl
2007-01-01
The author argues in this speech that one cannot expect students in the school system to know and understand the genius of Black history if the curriculum is Eurocentric, which is a residue of racism. He states that his comments are designed for the enlightenment of those who suffer from a school system that "hypocritically manipulates Black…
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…
Kohl, Arthur L.
1987-07-28
A concentrated aqueous black liquor containing carbonaceous material and alkali metal sulfur compounds is treated in a gasifier vessel containing a relatively shallow molten salt pool at its bottom to form a combustible gas and a sulfide-rich melt. The gasifier vessel, which is preferably pressurized, has a black liquor drying zone at its upper part, a black liquor solids gasification zone located below the drying zone, and a molten salt sulfur reduction zone which comprises the molten salt pool. A first portion of an oxygen-containing gas is introduced into the gas space in the gasification zone immediatley above the molten salt pool. The remainder of the oxygen-containing gas is introduced into the molten salt pool in an amount sufficient to cause gasification of carbonaceous material entering the pool from the gasification zone but not sufficient to create oxidizing conditions in the pool. The total amount of the oxygen-containing gas introduced both above the pool and into the pool constitutes between 25 and 55% of the amount required for complete combustion of the black liquor feed. A combustible gas is withdrawn from an upper portion of the drying zone, and a melt in which the sulfur content is predominantly in the form of alkali metal sulfide is withdrawn from the molten salt sulfur reduction zone.
Trichomicosis pubis: black variety.
Neri, I.; Frassetto, A; Pasquinelli, G.; Patrizi, A.
1994-01-01
A case of a 25 year old man with the black variety of trichomicosis pubis is presented on account of its extreme rareity. Scanning electron microscopy confirms that trichomicosis pubis is caused by bacterial colonisation of the pubic hair and shows that bacteria are able to penetrate cuticular horny cells directly through their free plasma membrane.
International Nuclear Information System (INIS)
We investigate the structure of the steady-state force-free magnetosphere around a Kerr black hole in various astrophysical settings. The solution Ψ(r, θ) depends on the distributions of the magnetic field line angular velocity ω(Ψ) and the poloidal electric current I(Ψ). These are obtained self-consistently as eigenfunctions that allow the solution to smoothly cross the two singular surfaces of the problem, the inner light surface inside the ergosphere, and the outer light surface, which is the generalization of the pulsar light cylinder. Magnetic field configurations that cross both singular surfaces (e.g., monopole, paraboloidal) are uniquely determined. Configurations that cross only one light surface (e.g., the artificial case of a rotating black hole embedded in a vertical magnetic field) are degenerate. We show that, similar to pulsars, black hole magnetospheres naturally develop an electric current sheet that potentially plays a very important role in the dissipation of black hole rotational energy and in the emission of high-energy radiation.
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.
Rouse, Donald E.
This study describes and assesses the basic problems of black males who enter educational administration as a career, showing the relationship between their cultural background and their aspirations in the field of administration of a large city school system. The role taken by the researcher is that of participant-observer. The collection of…
Observational Evidence for Black Holes
Narayan, Ramesh; McClintock, Jeffrey E.
2013-01-01
Astronomers have discovered two populations of black holes: (i) stellar-mass black holes with masses in the range 5 to 30 solar masses, millions of which are present in each galaxy in the universe, and (ii) supermassive black holes with masses in the range 10^6 to 10^{10} solar masses, one each in the nucleus of every galaxy. There is strong circumstantial evidence that all these objects are true black holes with event horizons. The measured masses of supermassive black hole are strongly corr...
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.
Statistical mechanics of black holes
International Nuclear Information System (INIS)
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
Kao, Robert
2010-01-01
Get the most juice out of your BlackBerry handheld!. Feature-rich and complex, the BlackBerry is the number one smartphone in the corporate world is among the most popular handhelds for business users. This new and updated edition includes all the latest and greatest information on new and current BlackBerry mobile devices. Covering a range of valuable how-to topics, this helpful guide explores the BlackBerry's most useful features, techniques for getting the most out of your BlackBerry, and practical information about power usage.: Covers all aspects of the number one smartphone in the corpor
Prisons of light : black holes
Ferguson, Kitty
What is a black hole? Could we survive a visit to one -- perhaps even venture inside? Have we yet discovered any real black holes? And what do black holes teach us about the mysteries of our Universe? These are just a few of the tantalizing questions examined in this tour-de-force, jargon-free review of one of the most fascinating topics in modern science. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light - Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.
Point mass Cosmological Black Holes
Firouzjaee, Javad T
2016-01-01
Real black holes in the universe are located in the expanding accelerating background which are called the cosmological black holes. Hence, it is necessary to model these black holes in the cosmological background where the dark energy is the dominant energy. In this paper, we argue that most of the dynamical cosmological black holes can be modeled by point mass cosmological black holes. Considering the de Sitter background for the accelerating universe, we present the point mass cosmological background in the cosmological de Sitter space time. Our work also includes the point mass black holes which have charge and angular momentum. We study the mass, horizons, redshift structure and geodesics properties for these black holes.
Khalil, Kareem
2012-12-01
Granulation, the process of formation of granules from a combination of base powders and binder liquids, has been a subject of research for almost 50 years, studied extensively for its vast applications, primarily to the pharmaceutical industry sector. The principal aim of granulation is to form granules comprised of the active pharmaceutical ingredients (API’s), which have more desirable handling and flowability properties than raw powders. It is also essential to ensure an even distribution of active ingredients within a tablet with the goal of achieving time‐controlled release of drugs. Due to the product‐specific nature of the industry, however, data is largely empirical [1]. For example, the raw powders used can vary in size by two orders of magnitude with narrow or broad size distributions. The physical properties of the binder liquids can also vary significantly depending on the powder properties and required granule size. Some significant progress has been made to better our understanding of the overall granulation process [1] and it is widely accepted that the initial nucleation / wetting stage, when the binder liquid first wets the powders, is key to the whole process. As such, many experimental studies have been conducted in attempt to elucidate the physics of this first stage [1], with two main mechanisms being observed – classified by Ivenson [1] as the “Traditional description” and the “Modern Approach”. See Figure 1 for a graphical definition of these two mechanisms. Recent studies have focused on the latter approach [1] and a new, exciting development in this field is the Liquid Marble. This interesting formation occurs when a liquid droplet interacts with a hydrophobic (or superhydrophobic) powder. The droplet can become encased in the powder, which essentially provides a protective “shell” or “jacket” for the liquid inside [2]. The liquid inside is then isolated from contact with other solids or liquids and has some
Liquid-liquid extraction columns
International Nuclear Information System (INIS)
A liquid-liquid extraction for use for example, in the solvent extraction of uranium and/or plutonium from an aqueous phase, comprises a perforated plate packing in which each plate has flanges associated with its perforations, which flanges project upstream with respect to the disperse phase flow direction so as to define a collecting zone for disperse phase droplets which thereby form a film or layer of the disperse phase component on the upstream face of each plate. In this way, droplet formation at the perforations of each plate is not significantly influenced by variations of the wetting characteristics of the plate with time. (author)
Liquid-liquid extraction columns
Energy Technology Data Exchange (ETDEWEB)
Lonie, S.J.
1986-10-15
A liquid-liquid extraction for use for example, in the solvent extraction of uranium and/or plutonium from an aqueous phase, comprises a perforated plate packing in which each plate has flanges associated with its perforations, which flanges project upstream with respect to the disperse phase flow direction so as to define a collecting zone for disperse phase droplets which thereby form a film or layer of the disperse phase component on the upstream face of each plate. In this way, droplet formation at the perforations of each plate is not significantly influenced by variations of the wetting characteristics of the plate with time.
Caged black holes: Black holes in compactified spacetimes. I. Theory
International Nuclear Information System (INIS)
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
Experiments on black liquor splashplate nozzle performance
Energy Technology Data Exchange (ETDEWEB)
Nieminen, K.
1996-12-31
The performance of a throttled black liquor splashplate nozzle was studied in this work. A series of industrial-scale experiments were performed using mass flow rate as a variable at a fixed temperature. The experiments were carried out in a spraying chamber next to the recovery boiler with real mill liquor. The disintegration process of the liquor sheet was videotaped for analyzing. The mass flow rate distribution was measured with a collector. The liquor drops produced by the nozzle were videotaped and measured with a video image analysis technique. The industrial-scale experiments were afterwards repeated on a small scale in the laboratory environment which made it possible to study the liquid sheet disintegration process thoroughly. The small-scale experiments were carried out with a solution of water and glycerol and a splashplate nozzle of approximately one tenth the size of full-scale nozzle. The whole liquid sheet and close-up exposures of the plate area were videotaped. However, the videotaping equipment (camera and objective) were not capable of observing the very thin and transparent liquid sheet. The mass flow rate distribution was measured with steps of 2.5 deg from the plate centerline with a collector device. The drop sizes were measured from various sheet angles with Malvern Particle Sizer and a phase Doppler particle anemometer (Aerometrics). The modeling was based on dimensional analysis. The objective was to compare these two experimental settings and to find out whether small-scale experiments can be used in predicting the spraying characteristics in the full-scale. It was also of interest to test the measured black liquor drop sizes against drop size correlations obtained from the literature. (31 refs.)
Liquid Cloud Responses to Soot
Koch, D. M.
2010-12-01
Although soot absorption warms the atmosphere, soot may cause climate cooling due to its effects on liquid clouds, including contribution to cloud condensation nuclei (CCN) and semi-direct effects. Six global models that include aerosol microphysical schemes conducted three soot experiments. The average model cloud radiative response to biofuel soot (black and organic carbon), including both indirect and semi-direct effects, is -0.12 Wm-2, comparable in size but opposite in sign to the respective direct atmospheric warming. In a more idealized fossil fuel black carbon only experiment, some models calculated a positive cloud response because the soot provided a deposition sink for sulfate, decreasing formation of more viable CCN. Biofuel soot particles were typically assumed to be larger and more hygroscopic than for fossil fuel soot and therefore caused more negative forcing, as also found in previous studies. Diesel soot (black and organic carbon) experiments had relatively smaller cloud impacts with five of the models competition of opposing effects on the CCN population make it difficult to extrapolate from idealized experiments to likely impacts of realistic potential emission changes. However, results so far suggest that soot-induced cloud-cooling effects are comparable in magnitude to the direct warming effects from soot absorption.
Antioxidant Activity of Lignin Phenolic Compounds Extracted from Kraft and Sulphite Black Liquors
Ana Paula Duarte; Cecília Baptista; Nuno Gil; Hélio Faustino
2010-01-01
The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in ter...
Directory of Open Access Journals (Sweden)
I. Cabrera-Munguia
2015-04-01
Full Text Available A 6-parametric asymptotically flat exact solution, describing a two-body system of asymmetric black dyons, is studied. The system consists of two unequal counterrotating Kerr–Newman black holes, endowed with electric and magnetic charges which are equal but opposite in sign, separated by a massless strut. The Smarr formula is generalized in order to take into account their contribution to the mass. The expressions for the horizon half-length parameters σ1 and σ2, as functions of the Komar parameters and of the coordinate distance, are displayed, and the thermodynamic properties of the two-body system are studied. Furthermore, the seven physical parameters satisfy a simple algebraic relation which can be understood as a dynamical scenario, in which the physical properties of one body are affected by the ones of the other body.
Bena, Iosif; Vercnocke, Bert
2012-01-01
We establish the relation between the structure governing supersymmetric and non-supersymmetric four- and five-dimensional black holes and multicenter solutions and Calabi-Yau flux compactifications of M-theory and type IIB string theory. We find that the known BPS and almost-BPS multicenter black hole solutions can be interpreted as GKP compactifications with (2,1) and (0,3) imaginary self-dual flux. We also show that the most general GKP compactification leads to new classes of BPS and non-BPS multicenter solutions. We explore how these solutions fit into N=2 truncations, and elucidate how supersymmetry becomes camouflaged. As a necessary tool in our exploration we show how the fields in the largest N=2 truncation fit inside the six-torus compactification of eleven-dimensional supergravity.
Clement, María E Gabach
2015-01-01
It is well known that celestial bodies tend to be spherical due to gravity and that rotation produces deviations from this sphericity. We discuss what is known and expected about the shape of black holes' horizons from their formation to their final, stationary state. We present some recent results showing that black hole rotation indeed manifests in the widening of their central regions, limits their global shapes and enforces their whole geometry to be close to the extreme Kerr horizon geometry at almost maximal rotation speed. The results depend only on the horizon area and angular momentum. In particular they are entirely independent of the surrounding geometry of the spacetime and of the presence of matter satisfying the strong energy condition. We also discuss the the relation of this result with the Hoop conjecture.
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.
Primary metals extraction by liquid membranes
International Nuclear Information System (INIS)
The extraction of copper and uranium by liquid membranes is presented. The recovery of uranium from wet process phosphoric acid is described. The development of this process has progressed through three stages, firstly the chemistry of uranium extraction as it pertains to liquid membrane systems. This was followed by continuous extraction tests on fresh black acid and on aged acid. Results on a 1 litre/minute pilot plant demonstrated that the process could be operated with a minimum of feed pretreatment and about 90% of uranium could be extracted. The extraction of copper from copper leach liquors is also described. (U.K.)
Purification of Flavonoids from Black Currant Juice by Nanodiafiltration
DEFF Research Database (Denmark)
Jensen, Morten Busch; Christensen, Knud Villy; Norddahl, Birgir
2009-01-01
from 1% to 44 % during the separation process. [1] F. Teillet, A. Boumendjel, J. Boutonnat, X. Ronot, Flavonoids as RTK Inhibitors and Potential Anticancer Agents, Medicinal Research Reviews, 2008, 28(5), 715-745 [2] M.J. Anttonen, R.O. Karjalainen, High-Performance Liquid Chromatography Analysis...... of Black Currant (Ribes nigrum L.) Fruit Phenolics Grown either Conventionally or Organically, Journal of Agricultural and Food Chemistry, 2006, 54, 7530-7538...
Bastos, C; Dias, N C; Prata, J N
2010-01-01
One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity regime and it is shown that the wave function vanishes in this limit.
Noncommutative Solitonic Black Hole
Chang-Young, Ee; Kimm, Kyoungtae; Lee, Daeho; Lee, Youngone
2011-01-01
We investigate solitonic black hole solutions in three dimensional noncommutative spacetime. We do this in gravity with negative cosmological constant coupled to a scalar field. Noncommutativity is realized with the Moyal product which is expanded up to first order in the noncommutativity parameter in two spatial directions. With numerical simulation we study the effect of noncommutativity by increasing the value of the noncommutativity parameter starting from commutative solutions. We find t...
Infinitely Coloured Black Holes
Mavromatos, Nick E.; Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom)
1999-01-01
We formulate the field equations for $SU(\\infty)$ Einstein-Yang-Mills theory, and find spherically symmetric black-hole solutions. This model may be motivated by string theory considerations, given the enormous gauge symmetries which characterize string theory. The solutions simplify considerably in the presence of a negative cosmological constant, particularly for the limiting cases of a very large cosmological constant or very small gauge field. The situation of an arbitrarily small gauge f...
International Nuclear Information System (INIS)
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.)
Roberto Casadio(INFN, Bologna); Andrea Giugno; Octavian Micu; Alessio Orlandi
2015-01-01
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 attractiv...
Helfer, Adam D
2011-01-01
I review elements of the foundations of black-hole theory with attention to problematic issues, and describe some techniques which either seem to help with the difficulties or at least investigate their scope. The definition of black holes via event horizons has been problematic because it depends on knowing the global structure of space-time; often attempts to avoid this (e.g. apparent horizons) require knowledge of the interior geometry. I suggest studying instead the holonomy relating the exterior neighborhood of the incipient horizon to the regime of distant observers; at least in the spherically symmetric case, this holonomy will develop certain universal features, in principle observable from signals emitted from infalling objects. I discuss the theory of quantum fields in curved space-time, and the difficulties with Hawking's prediction of black-hole radiation. I then show that the usual, very natural, theory of quantum fields in curved space-time runs into difficulties when applied to measurement prob...
Lyutikov, Maxim
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 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 $N_B = e \\Phi_\\infty /(\\pi c \\hbar)$, where $\\Phi_\\infty \\approx 2 \\pi^2 B_{NS} R_{NS}^3 /(P_{\\rm NS} c)$ is the initial magnetic flux through the hemisphere...
Thermal corpuscular black holes
Casadio, Roberto; Giugno, Andrea; Orlandi, Alessio
2015-06-01
We study the corpuscular model of an evaporating black hole consisting of a specific quantum state for a large number N of self-confined bosons. The single-particle spectrum contains a discrete ground state of energy m (corresponding to toy gravitons forming the black hole), and a gapless continuous spectrum (to accommodate for the Hawking radiation with energy ω >m ). Each constituent is in a superposition of the ground state and a Planckian distribution at the expected Hawking temperature in the continuum. We first find that, assuming the Hawking radiation is the leading effect of the internal scatterings, the corresponding 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 =N m and a Planckian distribution for E >M at the same Hawking temperature. From this collective state, we compute the partition function and obtain an entropy which reproduces the usual area law with a logarithmic correction precisely related with the Hawking component. By means of the horizon wave function for the system, we finally show the backreaction of modes with ω >m reduces the Hawking flux. Both corrections, to the entropy and to the Hawking flux, suggest the evaporation properly stops for vanishing mass, if the black hole is in this particular quantum state.
Bellucci, S; Marrani, A
2008-01-01
We review recent results in the study of attractor horizon geometries (with non-vanishing Bekenstein-Hawking entropy) of dyonic extremal d=4 black holes in supergravity. We focus on N=2, d=4 ungauged supergravity coupled to a number n_{V} of Abelian vector multiplets, outlining the fundamentals of the special Kaehler geometry of the vector multiplets' scalar manifold (of complex dimension n_{V}), and studying the 1/2-BPS attractors, as well as the non-BPS (non-supersymmetric) ones with non-vanishing central charge. For symmetric special Kaehler geometries, we present the complete classification of the orbits in the symplectic representation of the classical U-duality group (spanned by the black hole charge configuration supporting the attractors), as well as of the moduli spaces of non-BPS attractors (spanned by the scalars which are not stabilized at the black hole event horizon). Finally, we report on an analogous classification for N>2-extended, d=4 ungauged supergravities, in which also the 1/N-BPS attrac...
Non-Abelian magnetic black strings versus black holes
Mazharimousavi, S. Habib; Halilsoy, M.
2016-05-01
We present d+1 -dimensional pure magnetic Yang-Mills (YM) black strings (or 1-branes) induced by the d -dimensional Einstein-Yang-Mills-Dilaton black holes. The Born-Infeld version of the YM field makes our starting point which goes to the standard YM field through a limiting procedure. The lifting from black holes to black strings (with less number of fields) is done by adding an extra, compact coordinate. This amounts to the change of horizon topology from S^{d-2} to a product structure. Our black string in 5 dimensions is a rather special one, with uniform Hawking temperature and non-asymptotically flat structure. As the YM charge becomes large the string gets thinner to tend into a breaking point and transform into a 4-dimensional black hole.
Liquid for absorption of solar heat
Energy Technology Data Exchange (ETDEWEB)
Nakamura, T.; Iwamoto, Y.; Kadotani, K.; Marui, T.
1984-11-13
A liquid for the absorption of solar heat, useful as an heat-absorbing medium in water heaters and heat collectors comprises: a dispersing medium selected from the group consisting of propylene glycol, mixture of propylene glycol with water, mixture of propylene glycol with water and glycerin, and mixture of glycerin with water, a dispersant selected from the group consisting of polyvinylpyrrolidone, caramel, and mixture of polyvinylpyrrolidone with caramel, and a powdered activated carbon as a black coloring material.
Atkins, K R
1959-01-01
Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.
Continuous phase transition and critical behaviors of 3D black hole with torsion
International Nuclear Information System (INIS)
We study the phase transition and the critical behavior of the BTZ black hole with torsion obtained in (1 + 2)-dimensional Poincaré gauge theory. According to Ehrenfest’s classification, when the parameters in the theory are arranged properly, the BTZ black hole with torsion may possess the second-order phase transition which is also a smaller mass/larger mass black hole phase transition. Nevertheless, the critical behavior is different from the one in the van der Waals liquid/gas system. We also calculated the critical exponents of the relevant thermodynamic quantities, which are the same as the ones obtained in the Hořava-Lifshitz black hole and the Born–Infeld black hole. (paper)
Emanuel, K.; Lin, N.
2012-12-01
Virtually all assessments of tropical cyclone risk are based on historical records, which are limited to a few hundred years at most. Yet stronger TCs may occur in the future and at places that have not been affected historically. Such events lie outside the realm of historically based expectations and may have extreme impacts. Their occurrences are also often made explainable after the fact (e.g., Hurricane Katrina). We nickname such potential future TCs, characterized by rarity, extreme impact, and retrospective predictability, "black swans" (Nassim Nicholas Taleb, 2007). As, by definition, black swan TCs have yet to happen, statistical methods that solely rely on historical track data cannot predict their occurrence. Global climate models lack the capability to predict intense storms, even with a resolution as high as 14 km (Emanuel et al. 2010). Also, most dynamic downscaling methods (e.g., Bender et al. 2010) are still limited in horizontal resolution and are too expensive to implement to generate enough events to include rare ones. In this study, we apply a simpler statistical/deterministic hurricane model (Emanuel et al. 2006) to simulate large numbers of synthetic storms under a given (observed or projected) climate condition. The method has been shown to generate realistic extremes in various basins (Emanuel et al. 2008 and 2010). We also apply a hydrodynamic model (ADCIRC; Luettich et al. 1992) to simulate the storm surges generated by these storms. We then search for black swan TCs, in terms of the joint wind and surge damage potential, in the generated large databases. Heavy rainfall is another important TC hazard and will be considered in a future study. We focus on three areas: Tampa Bay in the U.S., the Persian Gulf, and Darwin in Australia. Tampa Bay is highly vulnerable to storm surge as it is surrounded by shallow water and low-lying lands, much of which may be inundated by a storm tide of 6 m. High surges are generated by storms with a broad
Stimulated emission and black holes
International Nuclear Information System (INIS)
The probability of a black hole emitting m particles when n particles are incident on the black hole was first derived by Bekenstein and Meisels, and later, using a different method, by Panangaden and Wald. In another paper by Bekenstein, it was argued that black holes should have stimulated emission in all modes including the nonsuperradiant ones. In this paper, we use a model based on quantum field theory. We show that Bose-Einstein statistics enhances the probability for particles to scatter in the same direction. We also prove that a black hole is equivalent to a perfect blackbody surrounded by a mirror. In our model, the black hole does not exhibit stimulated emission in nonsuperradiant modes. We also compare the black hole to a gray body
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.
Black Hole Masses are Quantized
Dvali, Gia; Mukhanov, Slava
2011-01-01
We give a simple argument showing that in any sensible quantum field theory the masses of black holes cannot assume continuous values and must be quantized. Our proof solely relies on Poincare-invariance of the asymptotic background, and is insensitive to geometric characteristics of black holes or other peculiarities of the short distance physics. Therefore, our results are equally-applicable to any other localized objects on asymptotically Poincare-invariant space, such as classicalons. By adding a requirement that in large mass limit the quantization must approximately account for classical results, we derive an universal quantization rule applicable to all classicalons (including black holes) in arbitrary number of dimensions. In particular, this implies, that black holes cannot emit/absorb arbitrarily soft quanta. The effect has phenomenological model-independent implications for black holes and other classicalons that may be created at LHC. We predict, that contrary to naive intuition, the black holes a...
International Nuclear Information System (INIS)
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
Small black holes on cylinders
International Nuclear Information System (INIS)
We find the metric of small black holes on cylinders, i.e. neutral and static black holes with a small mass in d-dimensional Minkowski space times a circle. The metric is found using an ansatz for black holes on cylinders proposed in J. High Energy Phys. 05, 032 (2002). We use the new metric to compute corrections to the thermodynamics which is seen to deviate from that of the (d+1)-dimensional Schwarzschild black hole. Moreover, we compute the leading correction to the relative binding energy which is found to be non-zero. We discuss the consequences of these results for the general understanding of black holes and we connect the results to the phase structure of black holes and strings on cylinders
Information Storage in Black Holes
Maia, M. D.
2005-01-01
The information loss paradox for Schwarzschild black holes is examined, using the ADS/CFT correspondence extended to the $M_6 (4,2)$ bulk. It is found that the only option compatible with the preservation of the quantum unitarity is when a regular remnant region of the black hole survives to the black hole evaporation process, where information can be stored and eventually retrieved.
Origin of supermassive black holes
Dokuchaev, V. I.; Eroshenko, Yu. N.; Rubin, S. G.
2007-01-01
The origin of supermassive black holes in the galactic nuclei is quite uncertain in spite of extensive set of observational data. We review the known scenarios of galactic and cosmological formation of supermassive black holes. The common drawback of galactic scenarios is a lack of time and shortage of matter supply for building the supermassive black holes in all galaxies by means of accretion and merging. The cosmological scenarios are only fragmentarily developed but propose and pretend to...
International Nuclear Information System (INIS)
In this talk, I present and discuss a number of attempts to construct black hole solutions in models with Warped Extra Dimensions. Then, a contact is made with models with Large Extra Dimensions, where black-hole solutions are easily constructed - here the focus will be on the properties of microscopic black holes and the possibility of using phenomena associated with them, such as the emission of Hawking radiation, to discover fundamental properties of our spacetime.
Black holes and the multiverse
Garriga, Jaume; Vilenkin, Alexander; Zhang, Jun
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.
Statistical Hair on Black Holes
International Nuclear Information System (INIS)
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
Pyrolytic carbon coated black silicon.
Shah, Ali; Stenberg, Petri; Karvonen, Lasse; Ali, Rizwan; Honkanen, Seppo; Lipsanen, Harri; Peyghambarian, N; Kuittinen, Markku; Svirko, Yuri; Kaplas, Tommi
2016-01-01
Carbon is the most well-known black material in the history of man. Throughout the centuries, carbon has been used as a black material for paintings, camouflage, and optics. Although, the techniques to make other black surfaces have evolved and become more sophisticated with time, carbon still remains one of the best black materials. Another well-known black surface is black silicon, reflecting less than 0.5% of incident light in visible spectral range but becomes a highly reflecting surface in wavelengths above 1000 nm. On the other hand, carbon absorbs at those and longer wavelengths. Thus, it is possible to combine black silicon with carbon to create an artificial material with very low reflectivity over a wide spectral range. Here we report our results on coating conformally black silicon substrate with amorphous pyrolytic carbon. We present a superior black surface with reflectance of light less than 0.5% in the spectral range of 350 nm to 2000 nm. PMID:27174890
Higher dimensional extremal black strings
H. W. Lee; Myung, Y. S.; Kim, Jin Young; Park, D. K.
1996-01-01
We investigate the five and six-dimensional black strings within Einstein-Maxwell theory. The extremal black strings are endowed with the null Killing symmetry. We study the propagation of Einstein-Maxwell modes in the extremal black string background by using this symmetry. It turns out that one graviton is a propagating mode, while both the Maxwell $F$ and three-form $H$ fields are non-propagating modes. Further we discuss the stability and classical hair of the extremal black strings.
How black holes saved relativity
Prescod-Weinstein, Chanda
2016-02-01
While there have been many popular-science books on the historical and scientific legacy of Albert Einstein's general theory of relativity, a gap exists in the literature for a definitive, accessible history of the theory's most famous offshoot: black holes. In Black Hole, the science writer Marcia Bartusiak aims for a discursive middle ground, writing solely about black holes at a level suitable for both high-school students and more mature readers while also giving some broader scientific context for black-hole research.
International Nuclear Information System (INIS)
In 1984, the Black Report published its results on the incidence of cancer and leukaemia in under 25-year olds in the village of Seascale and the surrounding area near the Sellafield nuclear reprocessing plant. Since then the pressure group core, as a result of their own independent research, has discovered ten additional cases of childhood cancer which should have been included in the Black Report and a Further two cases since the Black Report was written. This represents an additional 31% over the initial numbers considered and a review of the Black Report is sought. (UK)
Thermodynamics of Accelerating Black Holes
Appels, Michael; Kubiznak, David
2016-01-01
We address a long-standing problem of describing the thermodynamics of a charged 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.
Casadio, Roberto; Giugno, Andrea; Micu, Octavian; Orlandi, Alessio
2015-10-01
We review some features of BEC models of black holes obtained by means of the HWF formalism. We consider the KG equation for a toy graviton field coupled to a static matter current in spherical symmetry. 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 continuous occupation number. An attractive self-interaction is needed for bound states to form, so 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 HWF 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), in agreement with semiclassical calculations and different from a single very massive particle. The spectrum contains a discrete ground state of energy $m$ (the bosons forming the black hole), and a continuous spectrum with energy $\\omega > m$ (representing the Hawking radiation and modelled with a Planckian distribution at the expected Hawking temperature). 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 $M = N m$ and a Planckian distribution for $E > M$ at the same Hawking temperature. The partition function is then found to yield the usual area law for the entropy, with a logarithmic correction related with the Hawking component. The backreaction of modes with $\\omega > m$ is also shown to reduce the Hawking flux and the evaporation properly stops for vanishing mass.
Directory of Open Access Journals (Sweden)
Armen Yeranyan
2008-10-01
Full Text Available The general solutions of the radial attractor flow equations for extremal black holes, both for non-BPS with non-vanishing central charge Z and for Z = 0, are obtained for the so-called stu model, the minimal rank-3 N = 2 symmetric supergravity in d = 4 space-time dimensions. Comparisons with previous partial results, as well as the fake supergravity (first order formalism and an analysis of the marginal stability of corresponding D-brane configurations, are given.
Bastos, C.; Bertolami, O.; Dias, N. C.; Prata, J. N.
2010-04-01
One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity parameter, η. Furthermore, the t = r = 0 singularity is analysed in the noncommutative regime and it is shown that the wave function vanishes in this limit.
Energy Technology Data Exchange (ETDEWEB)
Bastos, C; Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Dias, N C; Prata, J N, E-mail: cbastos@fisica.ist.utl.p, E-mail: orfeu@cosmos.ist.utl.p, E-mail: ncdias@mail.telepac.p, E-mail: joao.prata@mail.telepac.p [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande, 376, 1749-024 Lisboa (Portugal)
2010-04-01
One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity parameter, {eta}. Furthermore, the t = r = 0 singularity is analysed in the noncommutative regime and it is shown that the wave function vanishes in this limit.
International Nuclear Information System (INIS)
One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity parameter, η. Furthermore, the t = r = 0 singularity is analysed in the noncommutative regime and it is shown that the wave function vanishes in this limit.
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
Energy Technology Data Exchange (ETDEWEB)
Pezoldt, Joerg [FG Nanotechnologie, Institut fuer Mikro- und Nanotechnologie, TU Ilmenau, Postfach 100565, 98684 Ilmenau (Germany); Kups, Thomas [FG Werkstoffe der Elektrotechnik, Institut fuer Mikro- und Nanotechnologien, TU Ilmenau, Postfach 1005765, 98684 Ilmenau (Germany); Stubenrauch, Mike [FG Mikromechanische Systeme, Institut fuer Mikro- und Nanotechnologien, TU Ilmenau, Postfach 1005765, 98684 Ilmenau (Germany); Fischer, Michael [FG Elektroniktechnologie, Institut fuer Mikro- und Nanotechnologien, TU Ilmenau, Postfach 1005765, 98684 Ilmenau (Germany)
2011-03-15
Black silicon is a fascinating multipurpose modification of bulk silicon which can be fabricated in a selforganized structure formation process during dry etching of bare silicon wafer leading to the formation of a high density of silicon needles. The smallest dimension of the tips approaches values between 1 and 2 nm. The silicon nanostructure exhibits an extremely low diffuse reflectivity. The nanosized tips and their coating with fluorine doped nonstoichiometric silicon dioxide are responsible for cathodoluminescence in the blue-green and red regions of the visible spectra (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Holographic Black Hole Chemistry
Karch, Andreas
2015-01-01
Thermodynamic quantities associated with black holes in Anti-de Sitter space obey an interesting identity when the cosmological constant is included as one of the dynamical variables, the generalized Smarr relation. We show that this relation can easily be understood from the point of view of the dual holographic field theory. It amounts to the simple statement that the extensive thermodynamic quantities of a large $N$ gauge theory only depend on the number of colors, $N$, via an overall factor of $N^2$.
Black Holes, Black Swans, Black Magic: the Emerging Arts of Project Execution
Prieto, Bob
2013-01-01
Fluor Corporation executive to give Vecellio LectureBlacksburg, VA , September 16, 2013 Virginia Tech College of Engineering Bob Prieto, senior vice president, Fluor Corporation, will present the 2013 Vecellio Distinguished Lecture, titled “Black Holes, Black Swans, Black Magic: the Emerging Arts of Project Execution,” on Friday, Oct. 11 at 4 p.m. in Torgersen 2150. His talk will provide a whirlwind tour of some of the growing challenges in construction project execution and some of the emerg...
Adjustable liquid aperture to eliminate undesirable light in holographic projection.
Wang, Di; Liu, Chao; Li, Lei; Zhou, Xin; Wang, Qiong-Hua
2016-02-01
In this paper, we propose an adjustable liquid aperture to eliminate the undesirable light in a holographic projection. The aperture is based on hydrodynamic actuation. A chamber is formed with a cylindrical tube. A black droplet is filled in the sidewall of the cylinder tube and the outside space is the transparent oil which is immiscible with the black droplet. An ultrathin glass sheet is attached on the bottom substrate of the device and a black shading film is secured to the central area of the glass sheet. By changing the volume of the black droplet, the black droplet will move to the middle or sidewall due to hydrodynamic actuation, so the device can be used as an adjustable aperture. A divergent spherical wave and a solid lens are used to separate the focus planes of the reconstructed image and diffraction beams induced by the liquid crystal on silicon in the holographic projection. Then the aperture is used to eliminate the diffraction beams by adjusting the size of the liquid aperture and the holographic projection does not have undesirable light. PMID:26906784
2002-10-01
Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours [1] Summary An international team of astronomers [2], lead by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) , has directly observed an otherwise normal star orbiting the supermassive black hole at the center of the Milky Way Galaxy. Ten years of painstaking measurements have been crowned by a series of unique images obtained by the Adaptive Optics (AO) NAOS-CONICA (NACO) instrument [3] on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory. It turns out that earlier this year the star approached the central Black Hole to within 17 light-hours - only three times the distance between the Sun and planet Pluto - while travelling at no less than 5000 km/sec . Previous measurements of the velocities of stars near the center of the Milky Way and variable X-ray emission from this area have provided the strongest evidence so far of the existence of a central Black Hole in our home galaxy and, implicitly, that the dark mass concentrations seen in many nuclei of other galaxies probably are also supermassive black holes. However, it has not yet been possible to exclude several alternative configurations. In a break-through paper appearing in the research journal Nature on October 17th, 2002, the present team reports their exciting results, including high-resolution images that allow tracing two-thirds of the orbit of a star designated "S2" . It is currently the closest observable star to the compact radio source and massive black hole candidate "SgrA*" ("Sagittarius A") at the very center of the Milky Way. The orbital period is just over 15 years. The new measurements exclude with high confidence that the central dark mass consists of a cluster of unusual stars or elementary particles, and leave little doubt of the presence of a supermassive black hole at the centre of the galaxy in which we live . PR Photo 23a/02 : NACO image of the central region of the Milky Way
Area spectrum of slowly rotating black holes
Myung, Yun Soo
2010-01-01
We investigate the area spectrum for rotating black holes which are Kerr and BTZ black holes. For slowly rotating black holes, we use the Maggiore's idea combined with Kunstatter's method to derive their area spectra, which are equally spaced.
Spacetime Duality of BTZ Black Hole
Ho, Jeongwon; Kim, Won T.; Park, Young-Jai
1999-01-01
We consider the duality of the quasilocal black hole thermodynamics, explicitly the quasilocal black hole thermodynamic first law, in BTZ black hole solution as a special one of the three-dimensional low energy effective string theory.
Stability and critical phenomena of black holes and black rings
International Nuclear Information System (INIS)
We revisit the general topic of thermodynamical stability and critical phenomena in black hole physics, analyzing in detail the phase diagram of the five dimensional rotating black hole and the black rings discovered by Emparan and Reall. First we address the issue of microcanonical stability of these spacetimes and its relation to thermodynamics by using the so-called Poincare (or 'turning point') method, which we review in detail. We are able to prove that one of the black ring branches is always locally unstable, showing that there is a change of stability at the point where the two black ring branches meet. Next we study divergence of fluctuations, the geometry of the thermodynamic state space (Ruppeiner geometry) and compute the appropriate critical exponents and verify the scaling laws familiar from renormalization group theory in statistical mechanics. We find that, at extremality, the behavior of the system is formally very similar to a second order phase transition
Supersymmetric black holes in string theory
Mohaupt, T.
2007-01-01
We review recent developments concerning supersymmetric black holes in string theory. After a general introduction to the laws of black hole mechanics and to black hole entropy in string theory, we discuss black hole solutions in N=2 supergravity, special geometry, the black hole attractor equations and the underlying variational principle. Special attention is payed to the crucial role of higher derivative corrections. Finally we discuss black hole partition functions and their relation to t...
Casadio, Roberto; Micu, Octavian; Orlandi, Alessio
2015-01-01
We review some features of BEC models of black holes obtained by means of the HWF formalism. We consider the KG equation for a toy graviton field coupled to a static matter current in spherical symmetry. 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 continuous occupation number. An attractive self-interaction is needed for bound states to form, so 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 HWF 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), in agreement with semiclassical calculations and different from a single very massive particle. The spectrum contains a...
Thermal corpuscular black holes
Casadio, Roberto; Orlandi, Alessio
2015-01-01
We study the corpuscular model of an evaporating black hole consisting of a specific quantum state for a large number $N$ of self-confined bosons. The single-particle spectrum contains a discrete ground state of energy $m$ (corresponding to toy gravitons forming the black hole), and a gapless continuous spectrum (to accommodate for the Hawking radiation with energy $\\omega>m$). Each constituent is in a superposition of the ground state and a Planckian distribution at the expected Hawking temperature in the continuum. We first find that, assuming the Hawking radiation is the leading effect of the internal scatterings, the corresponding $N$-particle state can be collectively described by a single-particle wave-function given by a superposition of a total ground state with energy $M=N\\,m$ and a Planckian distribution for $E>M$ at the same Hawking temperature. From this collective state, we compute the partition function and obtain an entropy which reproduces the usual area law with a logarithmic correction preci...
Hawking, Stephen William
1996-01-01
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 shown that scattering in such topological fluctuations leads to loss of quantum coherence, or in other words, to a superscattering matrix \\ that does not factorise into an S matrix and its adjoint. This loss of quantum coherence is very small at low energies for everything except scalar fields, leading to the prediction that we may never observe the Higgs particle. Another possible observational consequence may be that the \\theta angle of QCD is zero without having to invoke the problematical existence of a light axion. The pic...
Black hole thermodynamical entropy
Energy Technology Data Exchange (ETDEWEB)
Tsallis, Constantino [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rio de Janeiro, RJ (Brazil); Santa Fe Institute, Santa Fe, NM (United States); Cirto, Leonardo J.L. [Centro Brasileiro de Pesquisas Fisicas and National Institute of Science and Technology for Complex Systems, Rio de Janeiro, RJ (Brazil)
2013-07-15
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{sub BG} of a (3+1) black hole is proportional to its area L{sup 2} (L being a characteristic linear length), and not to its volume L{sup 3}. Similarly it exists the area law, so named because, for a wide class of strongly quantum-entangled d-dimensional systems, S{sub BG} is proportional to lnL if d=1, and to L{sup d-1} if d>1, instead of being proportional to L{sup 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.)
Belloni, T M
2016-01-01
The last two decades have seen a great improvement in our understand- ing of the complex phenomenology observed in transient black-hole binary systems, especially thanks to the activity of the Rossi X-Ray Timing Explorer satellite, com- plemented by observations from many other X-ray observatories and ground-based radio, optical and infrared facilities. Accretion alone cannot describe accurately the intricate behavior associated with black-hole transients and it is now clear that the role played by different kinds of (often massive) outflows seen at different phases of the outburst evolution of these systems is as fundamental as the one played by the accretion process itself. The spectral-timing states originally identified in the X-rays and fundamentally based on the observed effect of accretion, have acquired new importance as they now allow to describe within a coherent picture the phenomenology observed at other wave- length, where the effects of ejection processes are most evident. With a particular focu...
Quantum black hole evaporation
Schoutens, K; Verlinde, Erik; Schoutens, Kareljan; Verlinde, Erik; Verlinde, Herman
1993-01-01
We investigate a recently proposed model for a full quantum description of two-dimensional black hole evaporation, in which a reflecting boundary condition is imposed in the strong coupling region. It is shown that in this model each initial state is mapped to a well-defined asymptotic out-state, provided one performs a certain projection in the gravitational zero mode sector. We find that for an incoming localized energy pulse, the corresponding out-going state contains approximately thermal radiation, in accordance with semi-classical predictions. In addition, our model allows for certain acausal strong coupling effects near the singularity, that give rise to corrections to the Hawking spectrum and restore the coherence of the out-state. To an asymptotic observer these corrections appear to originate from behind the receding apparent horizon and start to influence the out-going state long before the black hole has emitted most of its mass. Finally, by putting the system in a finite box, we are able to deriv...
Gurvits, Grigoriy E; Tan, Amy
2014-08-21
Black hairy tongue (BHT) is a benign medical condition characterized by elongated filiform lingual papillae with typical carpet-like appearance of the dorsum of the tongue. Its prevalence varies geographically, typically ranging from 0.6% to 11.3%. Known predisposing factors include smoking, excessive coffee/black tea consumption, poor oral hygiene, trigeminal neuralgia, general debilitation, xerostomia, and medication use. Clinical presentation varies but is typically asymptomatic, although aesthetic concerns are common. Differential diagnosis includes pseudo-BHT, acanthosis nigricans, oral hairy leukoplakia, pigmented fungiform papillae of the tongue, and congenital melanocytic/melanotic nevi/macules. Clinical diagnosis relies on visual observation, detailed history taking, and occasionally microscopic evaluation. Treatment involves identification and discontinuation of the offending agent, modifications of chronic predisposing factors, patient's re-assurance to the benign nature of the condition, and maintenance of adequate oral hygiene with gentle debridement to promote desquamation. Complications of BHT (burning mouth syndrome, halitosis, nausea, gagging, dysgeusia) typically respond to therapy. Prognosis is excellent with treatment of underlying medical conditions. BHT remains an important medical condition which may result in additional burden on the patient and health care system and requires appropriate prevention, recognition and treatment. PMID:25152586
What, no black hole evaporation
International Nuclear Information System (INIS)
Tipler has claimed that the inward flux of negative energy across the horizon which (according to the semi-classical approximation) accompanies the evaporation of a black hole would cause a solar mass black hole to evaporate in less than a second. It is shown that this claim is in error. (orig.)
Nonlinear Electrodynamics and black holes
Breton, N; Breton, Nora; Garcia-Salcedo, Ricardo
2007-01-01
It is addressed the issue of black holes with nonlinear electromagnetic field, focussing mainly in the Born-Infeld case. The main features of these systems are described, for instance, geodesics, energy conditions, thermodynamics and isolated horizon aspects. Also are revised some black hole solutions of alternative nonlinear electrodynamics and its inconveniences.
Black Component of Dark Matter
Directory of Open Access Journals (Sweden)
A. V. Grobov
2014-01-01
Full Text Available A mechanism of primordial black hole formation with specific mass spectrum is discussed. It is shown that these black holes could contribute to the energy density of dark matter. Our approach is elaborated in the framework of universal extra dimensions.
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....
Educating Black Males with Dyslexia
Robinson, Shawn Anthony
2013-01-01
Much of the scholarship on Black males in the educational literature focuses on the achievement gap; their underrepresentation in gifted and advanced placement programs; their overrepresentation in special education programs and their high rates of school suspensions and expulsions. Although overrepresented in special education, Black males with…
Black raspberry: Korean vs. American
This fact sheet shows Korean black raspberry (Rubus coreanus) fruit, flower, and leaf features that distinguish them from their Rubus relatives, black raspberry (R. occidentalis) native to America. Common names with fruit characteristics, including berry size and pigment fingerprints, are summarized...
Reconceptualizing Retirement for Black Americans.
Gibson, Rose C.
1987-01-01
Examined subsample of nonworking older Black Americans (N=295) from the National Survey of Black Americans sample. Found four factors contributed significantly to respondents' unretired-retired status: indistinct line between lifetime and old age work patterns, view that occasional work is necessary, income from other than private pensions, and…
Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Ong, Yen Chin; /Taiwan, Natl. Taiwan U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC
2012-06-13
The anti-de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Horava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Horava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Horava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in {lambda} = 1 Horava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter {epsilon} close to unity. Sufficiently charged flat black holes for {epsilon} close to unity, and sufficiently charged positively curved black holes with {epsilon} close to zero, are also unstable. The implication to the Horava-Lifshitz holographic superconductor is discussed.
Prisons of Light - Black Holes
Ferguson, Kitty
1998-05-01
In this jargon-free review of one of the most fascinating topics in modern science, acclaimed science writer Kitty Ferguson examines the discovery of black holes, their nature, and what they can teach us about the mysteries of the universe. In search of the answers, we trace a star from its birth to its death throes, take a hypothetical journey to the border of a black hole and beyond, spend time with some of the world's leading theoretical physicists and astronomers, and take a whimsical look at some of the wild ideas black holes have inspired. Prisons of Light--Black Holes is comprehensive and detailed. Yet Kitty Ferguson's lightness of touch and down-to-earth analogies set this book apart from all others on black holes and make it a wonderfully stimulating and entertaining read.
Black Holes and Galaxy Metamorphosis
Holley-Bockelmann, K
2001-01-01
Supermassive black holes can be seen as an agent of galaxy transformation. In particular, a supermassive black hole can cause a triaxial galaxy to evolve toward axisymmetry by inducing chaos in centrophilic orbit families. This is one way in which a single supermassive black hole can induce large-scale changes in the structure of its host galaxy -- changes on scales far larger than the Schwarzschild radius ($O(10^{-5}) \\rm{pc}$) and the radius of influence of the black hole ($O(1)-O(100) \\rm{pc}$). We will discuss the transformative power of supermassive black holes in light of recent high resolution N-body realizations of cuspy triaxial galaxies.
Black holes and the multiverse
Garriga, Jaume; Zhang, Jun
2015-01-01
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 blac...
Quantum strings and black holes
Damour, Thibault Marie Alban Guillaume
2001-01-01
The transition between (non supersymmetric) quantum string states and Schwarzschild black holes is discussed. This transition occurs when the string coupling $g^2$ (which determines Newton's constant) increases beyond a certain critical value $g_c^2$. We review a calculation showing that self-gravity causes a typical string state of mass $M$ to shrink, as the string coupling $g^2$ increases, down to a compact string state whose mass, size, entropy and luminosity match (for the critical value $g_c^2 \\sim (M \\sqrt{\\alpha'})^{-1}$) those of a Schwarzschild black hole. This confirms the idea (proposed by several authors) that the entropy of black holes can be accounted for by counting string states. The level spacing of the quantum states of Schwarzschild black holes is expected to be exponentially smaller than their radiative width. This makes it very difficult to conceive (even Gedanken) experiments probing the discreteness of the quantum energy levels of black holes.
Evaluation of therapeutic pulmonary surfactants by thin liquid film methods.
Todorov, Roumen; Exerowa, Dotchi; Platikanov, Dimo; Bianco, Federico; Razzetti, Roberta
2015-08-01
An example of the application of the Black Foam Film (BFF) Method and the Wetting Film Method, using the Microinterferomertric and the Pressure Balance Techniques, for characterization interfacial properties of the animal derived therapeutic pulmonary surfactant preparations (TSP), is presented. BFF thickness, probability of black film formation, and disjoining pressure for foam films from TSP aqueous solutions are measured as well as the wetting properties of TSP solutions on solid surfaces with different hydrophobicity have been studied. Interfacial characteristics such as minimal surfactant concentration to obtain black film (critical concentration) and concentration at which a black film is 100% obtained (threshold concentration) are determined. An evaluation of the four widely used TSP – Curosurf, Infasurf, Survanta, and Alveofact – by these methods has been carried out. Thus the methods of the thin liquid films are useful tools for studying the interfacial properties of TSP solutions, as well as for their improvement. PMID:25132222
Bini, Donato; Bittencourt, Eduardo; Geralico, Andrea; Jantzen, Robert T.
2015-04-01
A general framework is developed to investigate the properties of useful choices of stationary spacelike slicings of stationary spacetimes whose congruences of timelike orthogonal trajectories are interpreted as the world lines of an associated family of observers, the kinematical properties of which in turn may be used to geometrically characterize the original slicings. On the other hand, properties of the slicings themselves can directly characterize their utility motivated instead by other considerations like the initial value and evolution problems in the 3-plus-1 approach to general relativity. An attempt is made to categorize the various slicing conditions or "time gauges" used in the literature for the most familiar stationary spacetimes: black holes and their flat spacetime limit.
Bini, Donato; Geralico, Andrea; Jantzen, Robert T
2015-01-01
A general framework is developed to investigate the properties of useful choices of stationary spacelike slicings of stationary spacetimes whose congruences of timelike orthogonal trajectories are interpreted as the world lines of an associated family of observers, the kinematical properties of which in turn may be used to geometrically characterize the original slicings. On the other hand properties of the slicings themselves can directly characterize their utility motivated instead by other considerations like the initial value and evolution problems in the 3-plus-1 approach to general relativity. An attempt is made to categorize the various slicing conditions or "time gauges" used in the literature for the most familiar stationary spacetimes: black holes and their flat spacetime limit.
Black powder removal in a Mexico gas pipeline
Energy Technology Data Exchange (ETDEWEB)
Morrow, John R. [TDW Services, Inc., New Castle, DE (United States); Drysdale, Colin; Warterfield, Bob D. [T.D.Williamson, Inc., Tulsa, OK (United States)
2008-07-01
This paper focuses on the cleaning methodology and operational constrains involved with the removal of black powder in a high pressure natural gas transmission pipeline. In this case, the accumulation of black powder along the pipeline system over the seven year period since it was put into service was creating significant problems in the areas of maintenance, customer relations, and cost to the pipeline operator due to clogging of filters, reduced gas flow, and penalties as result of non-compliant delivery contracts. The pipeline cleaning project consisted of running cleaning pigs or scrappers with batches of cleaning solution through each section of the pipeline while dealing with such factors as three (3) pipeline section lengths in excess of 160 kms (100 miles), gas flow velocity fluctuations, shutdowns, and gas delivery schedule requirements. The cleaning program for the entire pipeline system included the use of chemical and diesel based cleaning solution, running multiple cleaning pigs, liquid injection and separation system, mobile storage tanks, various equipment and personnel for logistical support. Upon completion of the cleaning program, the level of black powder and other solids in all pipeline sections was reduced to approximately 0.5% liquid/solid ratio and the pipeline system returned to normal optimum operation. (author.
2012-11-26
... Energy Regulatory Commission Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of Application for Partial Transfer of Licenses, and Soliciting Comments and Motions To Intervene On October 25, 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor)...
Rotating black hole and quintessence
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sushant G. [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Private Bag 54001, Durban (South Africa)
2016-04-15
We discuss spherically symmetric exact solutions of the Einstein equations for quintessential matter surrounding a black hole, which has an additional parameter (ω) due to the quintessential matter, apart from the mass (M). In turn, we employ the Newman-Janis complex transformation to this spherical quintessence black hole solution and present a rotating counterpart that is identified, for α = -e{sup 2} ≠ 0 and ω = 1/3, exactly as the Kerr-Newman black hole, and as the Kerr black hole when α = 0. Interestingly, for a given value of parameter ω, there exists a critical rotation parameter (a = a{sub E}), which corresponds to an extremal black hole with degenerate horizons, while for a < a{sub E}, it describes a nonextremal black hole with Cauchy and event horizons, and no black hole for a > a{sub E}. We find that the extremal value a{sub E} is also influenced by the parameter ω and so is the ergoregion. (orig.)
The renaissance of black phosphorus.
Ling, Xi; Wang, Han; Huang, Shengxi; Xia, Fengnian; Dresselhaus, Mildred S
2015-04-14
One hundred years after its first successful synthesis in the bulk form in 1914, black phosphorus (black P) was recently rediscovered from the perspective of a 2D layered material, attracting tremendous interest from condensed matter physicists, chemists, semiconductor device engineers, and material scientists. Similar to graphite and transition metal dichalcogenides (TMDs), black P has a layered structure but with a unique puckered single-layer geometry. Because the direct electronic band gap of thin film black P can be varied from 0.3 eV to around 2 eV, depending on its film thickness, and because of its high carrier mobility and anisotropic in-plane properties, black P is promising for novel applications in nanoelectronics and nanophotonics different from graphene and TMDs. Black P as a nanomaterial has already attracted much attention from researchers within the past year. Here, we offer our opinions on this emerging material with the goal of motivating and inspiring fellow researchers in the 2D materials community and the broad readership of PNAS to discuss and contribute to this exciting new field. We also give our perspectives on future 2D and thin film black P research directions, aiming to assist researchers coming from a variety of disciplines who are desirous of working in this exciting research field. PMID:25820173
Phase transition in black holes
Roychowdhury, Dibakar
2014-01-01
The present thesis is devoted towards the study of various aspects of the phase transition phenomena occurring in black holes defined in an Anti-de-Sitter (AdS) space. Based on the fundamental principles of thermodynamics and considering a grand canonical framework we examine various aspects of the phase transition phenomena occurring in AdS black holes. We analytically check that this phase transition between the smaller and larger mass black holes obey Ehrenfest relations defined at the critical point and hence confirm a second order phase transition. This include both the rotating and charged black holes in Einstein gravity. Apart from studying these issues, based on a canonical framework, we also investigate the critical behavior in charged AdS black holes. The scaling laws for these black holes are found to be compatible with the static scaling hypothesis. Finally, based on the usual framework of AdS/CFT duality, we investigate the phase transition phenomena occurring in charged hairy black holes defined...
A nonsingular rotating black hole
International Nuclear Information System (INIS)
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.)
Acceleration of Black Hole Universe
Zhang, Tianxi
2012-05-01
An alternative cosmological model called black hole universe has been recently proposed by the author. According to this model, the universe originated from a hot star-like black hole, and gradually grew up through a supermassive black hole to the present state by accreting ambient materials and merging with other black holes. The entire space is structured with an infinite number of layers hierarchically. The innermost three layers are the universe that we live, the outside space called mother universe, and the inside star-like and supermassive black holes called child universes. The outermost layer has an infinite radius and limits to zero for both the mass density and absolute temperature. All layers or universes are governed by the same physics, the Einstein general theory of relativity with the Robertson-Walker metric of space-time, and tend to expand outward physically. The evolution of the space structure is iterative. When one universe expands out, a new similar universe grows up from its inside. In this study. we will analyze the acceleration of black hole universe that accretes its ambient matter in an increasing rate. We will also compare the result obtained from the black hole universe model with the measurement of type Ia supernova and the result from the big bang cosmology.
Energy Technology Data Exchange (ETDEWEB)
Sherik, Abdelmounam [Saudi Aramco, Dhahran (Saudi Arabia)
2009-07-01
Despite its common occurrence in the gas industry, black powder is a problem that is not well understood across the industry, in terms of its chemical and physical properties, source, formation, prevention or management of its impacts. In order to prevent or effectively manage the impacts of black powder, it is essential to have knowledge of its chemical and physical properties, formation mechanisms and sources. The present paper is divided into three parts. The first part of this paper is a synopsis of published literature. The second part reviews the recent laboratory and field work conducted at Saudi Aramco Research and Development Center to determine the compositions, properties, sources and formation mechanisms of black powder in gas transmission systems. Microhardness, nano-indentation, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) techniques were used to analyze a large number of black powder samples collected from the field. Our findings showed that black powder is generated inside pipelines due to internal corrosion and that the composition of black powder is dependent on the composition of transported gas. The final part presents a summary and brief discussion of various black powder management methods. (author)
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.
A nonsingular rotating black hole
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Sushant G. [Jamia Millia Islamia, Centre for Theoretical Physics, New Delhi (India); University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematical Sciences, Durban (South Africa)
2015-11-15
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.)
Colloid-chemical properties of the black soap made by the national way
Directory of Open Access Journals (Sweden)
Zh. Toktarbay
2012-03-01
Full Text Available The surface tension, emulsion, the foaming ability, and washing action of the black soap made by national way is investigated. It is shown that it can be used as a washing-up liquid for clearing of firm surfaces from fat pollution.
Isolation and Purification of Anthocyanins from Black Bean Wastewater Using Macroporous Resins
Wang, Xiaoxi
2012-01-01
Isolation and purification of anthocyanins from black bean canning wastewater by column chromatography with macroporous resins were investigated in this study. Different adsorption materials and adsorption conditions were compared and the most effective material and adsorption conditions were selected to purify anthocyanins. Purified anthocyanins then were identified by high performance liquid chromatography electrospray tandem mass spectrometry. The most effective macroporous resin was selec...
Automatic liquid-liquid extraction system
International Nuclear Information System (INIS)
This invention concerns an automatic liquid-liquid extraction system ensuring great reproducibility on a number of samples, stirring and decanting of the two liquid phases, then the quantitative removal of the entire liquid phase present in the extraction vessel at the end of the operation. This type of system has many applications, particularly in carrying out analytical processes comprising a stage for the extraction, by means of an appropriate solvent, of certain components of the sample under analysis
The quantum gravitational black hole is neither black nor white
Singh, T P; Vaz, Cenalo
2004-01-01
Understanding the end state of black hole evaporation, the microscopic origin of black hole entropy, the information loss paradox, and the nature of the singularity arising in gravitational collapse - these are outstanding challenges for any candidate quantum theory of gravity. Recently, a midisuperspace model of quantum gravitational collapse has been solved using a lattice regularization scheme. It is shown that the mass of an eternal black hole follows the Bekenstein spectrum, and a related argument provides a fairly accurate estimate of the entropy. The solution also describes a quantized mass-energy distribution around a central black hole, which in the WKB approximation, is precisely Hawking radiation. The leading quantum gravitational correction makes the spectrum non-thermal, thus providing a plausible resolution of the information loss problem.
Black holes and Higgs stability
Tetradis, Nikolaos
2016-01-01
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.
Black Hole Bound State Metamorphosis
Chowdhury, Abhishek; Saha, Arunabha; Sen, Ashoke
2012-01-01
N=4 supersymmetric string theories contain negative discriminant states whose numbers are known precisely from microscopic counting formulae. On the macroscopic side, these results can be reproduced by regarding these states as multi-centered black hole configurations provided we make certain identification of apparently distinct multi-centered black hole configurations according to a precise set of rules. In this paper we provide a physical explanation of such identifications, thereby establishing that multi-centered black hole configurations reproduce correctly the microscopic results for the number of negative discriminant states without any ad hoc assumption.
Orbital resonances around black holes.
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. PMID:25768747
The Black Hole Information Problem
Polchinski, Joseph
2016-01-01
The black hole information problem has been a challenge since Hawking's original 1975 paper. It led to the discovery of AdS/CFT, which gave a partial resolution of the paradox. However, recent developments, in particular the firewall puzzle, show that there is much that we do not understand. I review the black hole, Hawking radiation, and the Page curve, and the classic form of the paradox. I discuss AdS/CFT as a partial resolution. I then discuss black hole complementarity and its limitations, leading to many proposals for different kinds of `drama.' I conclude with some recent ideas.
Evaporation of primordial black holes
Hawking, S. W.
The usual explanation of the isotropy of the universe is that inflation would have smoothed out any inhomogeneities. However, if the universe was initially fractal or in a foam like state, an overall inflation would have left it in the same state. I suggest that the universe did indeed begin with a tangled web of wormholes connecting pairs of black holes but that the inflationary expansion was unstable: wormholes that are slightly smaller correspond to black holes that are hotter than the cosmological background and evaporate away. This picture is supported by calculations with Raphael Bousso of the evaporation of primordial black holes in the s-wave and large N approximations.
Thermodynamics of Lifshitz black holes
Devecioǧlu, Deniz Olgu; Sarıoǧlu, Özgür
2011-06-01
We apply the recently extended conserved Killing charge definition of Abbott-Deser-Tekin formalism to compute, for the first time, the energies of analytic Lifshitz black holes in higher dimensions. We then calculate the temperature and the entropy of this large family of solutions, and study and discuss the first law of black hole thermodynamics. Along the way we also identify the possible critical points of the relevant quadratic curvature gravity theories. Separately, we also apply the generalized Killing charge definition to compute the energy and the angular momentum of the warped AdS3 black hole solution of the three-dimensional new massive gravity theory.
Can Black Hole Relax Unitarily?
Solodukhin, S N
2004-01-01
We review the way the BTZ black hole relaxes back to thermal equilibrium after a small perturbation and how it is seen in the boundary (finite volume) CFT. The unitarity requires the relaxation to be quasi-periodic. It is preserved in the CFT but is not obvious in the case of the semiclassical black hole the relaxation of which is driven by complex quasi-normal modes. We discuss two ways of modifying the semiclassical black hole geometry to maintain unitarity: the (fractal) brick wall and the worm-hole modification. In the latter case the entropy comes out correctly as well.
Quantum black hole without singularity
Kiefer, Claus
2015-01-01
We discuss the quantization of a spherical dust shell in a rigorous manner. Classically, the shell can collapse to form a black hole with a singularity. In the quantum theory, we construct a well-defined self-adjoint extension for the Hamilton operator. As a result, the evolution is unitary and the singularity is avoided. If we represent the shell initially by a narrow wave packet, it will first contract until it reaches the region where classically a black hole would form, but then re-expands to infinity. In a way, the state can be interpreted as a superposition of a black hole with a white hole.
Ribe, Neil; Habibi, Mehdi; Hosseini, Hossein; Hassan Khatami, Mohammad
2011-11-01
Supercoiling is defined as the large-scale secondary coiling of a slender body that is already coiled at a smaller scale (e.g., telephone cords and DNA strands). We demonstrate experimentally a novel fluid-mechanical form of supercoiling that occurs in the context of the familiar ``liquid rope coiling'' instability of a thin thread of viscous fluid falling onto a rigid surface. Under appropriate conditions, the coiling instability generates a tall pile of coils in the form of a hollow cylindrical column, which in turn becomes unstable to a secondary coiling instability with a frequency ~ 10 % of the primary one. To place this phenomenon in a broader context, we determine experimentally the phase diagram for the different possible behaviors of the thread (stagnation flow, simple coiling, rotatory folding, periodic column collapse, supercoiling) in the space of the fluid viscosity, the flow rate, and the fall height. We formulate a mathematical model for supercoiling by combining a thin-shell description of the column wall with a slender-thread description of the column as a whole. This leads to a set of coupled ordinary differential equations in one space dimension (the arclength along the axis of the coiling column) that we solve numerically using a continuation method. A comparison of the predicted and observed frequencies of secondary coiling will be shown.
(Liquid + liquid) equilibria of perfluorocarbons with fluorinated ionic liquids
International Nuclear Information System (INIS)
Highlights: • (Liquid + liquid) equilibria perfluorocarbons and fluorinated ionic liquids. • Non-Random Two Liquid model was successfully applied. • Thermodynamic functions that describe the solvation process were calculated. -- Abstract: In order to evaluate the feasibility of partially replace perfluorocarbons (PFCs) with fluorinated ionic liquids (FILs) in PFCs-in-water emulsions, usually used for biomedical purposes, herein the (liquid + liquid) phase equilibria of FILs containing fluorinated chains longer than four carbons with PFCs were carried out in a wide range of temperatures. With this goal in mind, two PFCs (perfluorooctane and perfluorodecalin) were selected and the (liquid + liquid) equilibria of the binary mixtures of these PFCs and FILs were studied at atmospheric pressure in a temperature range from T (293.15 to 343.15) K. For these studies, FILs containing ammonium, pyridinium and imidazolium cations and different anions with fluorocarbon alkyl chains between 4 and 8 were included. Additionally, Non-Random Two Liquid (NRTL) thermodynamic model was successfully applied to correlate the behaviour of the PFCs + FILs binary mixtures. Moreover, thermodynamic functions that describe the solvation process were calculated from the experimental data
Accretion, Primordial Black Holes and Standard Cosmology
Nayak, Bibekananda; Singh, Lambodar Prasad
2009-01-01
Primordial Black Holes evaporate due to Hawking radiation. We find that the evaporation time of primordial black holes increase when accretion of radiation is included.Thus depending on accretion efficiency more and more number of primordial black holes are existing today, which strengthens the idea that the primordial black holes are the proper candidate for dark matter.
Black Hole Complementary Principle and Noncommutative Membrane
International Nuclear Information System (INIS)
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.
Graduating Black Males: A Generic Qualitative Study
Bell, Edward E.
2014-01-01
Black males face a difficult educational battle. Across America, graduation statistics for Black males are sobering. The purpose of this study was to explore why Black males drop out of school and to examine the current employment status of the study participants. The research took place in rural North Carolina. Fifteen Black American male high…
Interracial Sex Contact: Emphasis on Black Americans.
Conyers, James E.
1977-01-01
The author discusses different social and historical factors surrounding four kinds of interracial sexual contact: (1) between Blacks from different parts of Africa; (2) between Blacks and American Indians; (3) between Black males and White females; and (4) between White males and Black females. He holds that miscegenation does nothing to solve…
The Core Journal Concept in Black Studies
Weissinger, Thomas
2010-01-01
Black Studies scholars have shown interest in the core journal concept. Indeed, the idea of core journals for the study of the Black experience has changed several times since 1940. While Black Studies scholars are citing Black Studies journals with frequency, they also cite traditional disciplinary journals a great deal of the time. However,…
Accretion, primordial black holes and standard cosmology
Indian Academy of Sciences (India)
B Nayak; P Singh
2011-01-01
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 are the proper candidates for dark matter.
Towards a Theory of Quantum Black Hole
Berezin, V.
2001-01-01
We describe some specific quantum black hole model. It is pointed out that the origin of a black hole entropy is the very process of quantum gravitational collapse. The quantum black hole mass spectrum is extracted from the mass spectrum of the gravitating source. The classical analog of quantum black hole is constructed.
Cryo-Etched Black Silicon for Use as Optical Black
Yee, Karl Y.; White, Victor E.; Mouroulis, Pantazis; Eastwood, Michael L.
2011-01-01
Stray light reflected from the surface of imaging spectrometer components in particular, the spectrometer slit degrade the image quality. A technique has been developed for rapid, uniform, and cost-effective black silicon formation based on inductively coupled plasma (ICP) etching at cryogenic temperatures. Recent measurements show less than 1-percent total reflectance from 350 2,500 nm of doped black silicon formed in this way, making it an excellent option for texturing of component surfaces for reduction of stray light. Oxygen combines with SF6 + Si etch byproducts to form a passivation layer atop the Si when the etch is performed at cryogenic temperatures. Excess flow of oxygen results in micromasking and the formation of black silicon. The process is repeatable and reliable, and provides control over etch depth and sidewall profile. Density of the needles can be controlled to some extent. Regions to be textured can be patterned lithographically. Adhesion is not an issue as the nanotips are part of the underlying substrate. This is in contrast to surface growth/deposition techniques such as carbon nanotubes (CNTs). The black Si surface is compatible with wet processing, including processing with solvents, the textured surface is completely inorganic, and it does not outgas. In radiometry applications, optical absorbers are often constructed using gold black or CNTs. This black silicon technology is an improvement for these types of applications.
Erratic Black Hole Regulates Itself
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
Statistical mechanics of extended black objects
International Nuclear Information System (INIS)
We extend the considerations of a previous paper on black hole statistical mechanics to the case of black extended objects such as black strings and black membranes in 10-dimensional space-time. We obtain a general expression for the Euclidean action of quantum black p-branes and derive their corresponding degeneracy of states. The statistical mechanics of a gas of black p-branes is then analyzed in the microcanonical ensemble. As in the case of black holes, the equilibrium state is not thermal and the stable configuration is the one for which a single black object carries most of the energy. Again, neutral black p-branes obey the bootstrap condition and it is then possible to argue that their scattering amplitudes satisfy crossing symmetry. Finally, arguments identifying quantum black p-branes with ordinary quantum branes of different dimensionality are presented
Black hole evaporation: a paradigm
International Nuclear Information System (INIS)
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
Switching off black hole evaporation
International Nuclear Information System (INIS)
The inclusion of the back-reaction in the Hawking effect leads to the result that, if vector boson fields predominate in nature, then black holes stop evaporating when their mass reaches a non-vanishing limiting value. (author)
Formation of Supermassive Black Holes
Volonteri, Marta
2010-01-01
Evidence shows that massive black holes reside in most local galaxies. Studies have also established a number of relations between the MBH mass and properties of the host galaxy such as bulge mass and velocity dispersion. These results suggest that central MBHs, while much less massive than the host (~ 0.1%), are linked to the evolution of galactic structure. In hierarchical cosmologies, a single big galaxy today can be traced back to the stage when it was split up in hundreds of smaller components. Did MBH seeds form with the same efficiency in small proto-galaxies, or did their formation had to await the buildup of substantial galaxies with deeper potential wells? I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I will discuss black hole formation processes for `seed' black holes that are likely to place at early cosmic epochs, and possible observational tests of these scenarios.
Black generation using lightness scaling
Cholewo, Tomasz J.
1999-12-01
This paper describes a method for constructing a lookup table relating a 3D CMY coordinate system to CMYK colorant amounts in a way that maximizes the utilization of the printer gamut volume. The method is based on an assumption, satisfied by most printers, that adding a black colorant to any combination of CMY colorants does not result in a color with more chroma. Therefore the CMYK gamut can be obtained from the CMY gamut by expanding it towards lower lightness values. Use of black colorant on the gray axis is enforced by modifying the initial distribution of CMY points through an approximate black generation transform. Lightness values of a resulting set of points in CIELAB space are scaled to fill the four-color gamut volume. The output CMYK values corresponding to the modified CIELAB colors are found by inverting a printer model. This last step determines a specific black use rate which can depend on the region of the color space.
Black hole thermodynamics from decoherence
Guo, Xiao-Kan
2015-01-01
We present an approach to the four laws of black hole thermodynamics by utilizing the thermodynamics of quantum coherence. Firstly, Hawking effect is attributed to the decoherence of the two-mode squeezed state in a black hole spacetime. Then use is made of the relative entropy between undecohered and decohered squeezed states whose monotonicity gives the zeroth and the second law, while the first law can be obtained either by the vanishing of the first derivative of relative entropy or by studying the effective thermal model generated by the modular Hamiltonian. Futhermore, information-theoretic arguments give a Planck's form of the third law of black hole thermodynamics. With this approach we can understand the laboratory analogues of black holes solely by quantum theory. This approach also opens a way to reconstruct classical geometry from quantum gravity.
Black hole accretion disc impacts
Pihajoki, P.
2016-04-01
We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.
Black hole accretion disc impacts
Pihajoki, Pauli
2015-01-01
We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength {\\lambda} = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.
Black hole interior mass formula
International Nuclear Information System (INIS)
We argue by explicit computations that, although the area product, horizon radii product, entropy product, and irreducible mass product of the event horizon and Cauchy horizon are universal, the surface gravity product, the surface temperature product and the Komar energy product of the said horizons do not seem to be universal for Kerr-Newman black hole spacetimes. We show the black hole mass formula on the Cauchy horizon following the seminal work by Smarr [Phys Rev Lett 30:71 (1973), Phys Rev D 7:289 (1973)] for the outer horizon. We also prescribe the four laws of black hole mechanics for the inner horizon. A new definition of the extremal limit of a black hole is discussed. (orig.)
THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION
Institute of Scientific and Technical Information of China (English)
Yuan-yuanJia
2004-01-01
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China's papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%-40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION
Institute of Scientific and Technical Information of China (English)
Yuan-yuan Jia
2004-01-01
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China′s papermaking industry. It is treated by alkali recovery,in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20% ～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
WU, Jing; Mu, Lixian; Zhuang, Li; Han, Yi; Liu, Tong; Jun LI; Yang, Yuan; Yang, Hailong; Wei, Lin
2015-01-01
Background Several antimicrobial peptides (AMPs) belonging to the cecropin family have been identified from the salivary glands of different black fly species, however, the immunological functions for these molecules were poorly understood. Methods A novel cecropin-like antimicrobial peptide (SibaCec) was purified using reverse phase high-performance liquid chromatography (RP-HPLC) from the salivary glands of the black fly Simulium bannaense. The amino acid sequence of SibaCec was determined ...
Zhang, Tianxi
2014-06-01
The black hole universe model is a multiverse model of cosmology recently developed by the speaker. According to this new model, our universe is a fully grown extremely supermassive black hole, which originated from a hot star-like black hole with several solar masses, and gradually grew up from a supermassive black hole with million to billion solar masses to the present state with trillion-trillion solar masses by accreting ambient matter or merging with other black holes. The entire space is structured with infinite layers or universes hierarchically. The innermost three layers include the universe that we live, the inside star-like and supermassive black holes called child universes, and the outside space called mother universe. The outermost layer is infinite in mass, radius, and entropy without an edge and limits to zero for both the matter density and absolute temperature. All layers are governed by the same physics and tend to expand physically in one direction (outward or the direction of increasing entropy). The expansion of a black hole universe decreases its density and temperature but does not alter the laws of physics. The black hole universe evolves iteratively and endlessly without a beginning. When one universe expands out, a new similar one is formed from inside star-like and supermassive black holes. In each of iterations, elements are resynthesized, matter is reconfigurated, and the universe is renewed rather than a simple repeat. The black hole universe is consistent with the Mach principle, observations, and Einsteinian general relativity. It has only one postulate but is able to explain all phenomena occurred in the universe with well-developed physics. The black hole universe does not need dark energy for acceleration and an inflation epoch for flatness, and thus has a devastating impact on the big bang model. In this talk, I will present how this new cosmological model explains the various aspects of the universe, including the origin
Comments on Black Holes in Matrix Theory
Horowitz, Gary T.; Martinec, Emil J.
1997-01-01
The recent suggestion that the entropy of Schwarzschild black holes can be computed in matrix theory using near-extremal D-brane thermodynamics is examined. It is found that the regime in which this approach is valid actually describes black strings stretched across the longitudinal direction, near the transition where black strings become unstable to the formation of black holes. It is argued that the appropriate dynamics on the other (black hole) side of the transition is that of the zero m...
Massive Black Holes: formation and evolution
Rees, Martin J.; Volonteri, Marta
2007-01-01
Supermassive black holes are nowadays believed to reside in most local galaxies. Observations have revealed us vast information on the population of local and distant black holes, but the detailed physical properties of these dark massive objects are still to be proven. Accretion of gas and black hole mergers play a fundamental role in determining the two parameters defining a black hole: mass and spin. We briefly review here the basic properties of the population of supermassive black holes,...
Regular black hole in three dimensions
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.
Regular black hole in three dimensions
International Nuclear Information System (INIS)
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 the thermodynamics of this black hole with that of a non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy. (orig.)
Regular black hole in three dimensions
Energy Technology Data Exchange (ETDEWEB)
Myung, Yun Soo [Inje University, Institute of Basic Science and School of Computer Aided Science, Gimhae (Korea); Yoon, Myungseok [Sogang University, Center for Quantum Spacetime, Seoul (Korea)
2009-07-15
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 the thermodynamics of this black hole with that of a non-rotating BTZ black hole. The first-law of thermodynamics is not compatible with the Bekenstein-Hawking entropy. (orig.)
Vacuum metastability with black holes.
Burda, Philipp; Gregory, Ruth; Moss, Ian
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 evapor...
Energy Extraction from Black Holes
Straumann, Norbert
2007-01-01
In this lecture I give an introduction to the rotational energy extraction of black holes by the electromagnetic Blandford-Znajek process and the generation of relativistic jets. After some basic material on the electrodynamics of black hole magnetospheres, we derive the most important results of Blandford and Znajek by making use of Kerr-Schild coordinates, which are regular on the horizon. In a final part we briefly describe results of recent numerical simulations of accretion flows on rota...
Myers, R C
2001-01-01
This is a short summary of my lectures given at the Fourth Mexican School on Gravitation and Mathematical Physics. These lectures gave a brief introduction to black holes in string theory, in which I primarily focussed on describing some of the recent calculations of black hole entropy using the statistical mechanics of D-brane states. The following overview will also provide the interested students with an introduction to the relevant literature.
Charged rotating noncommutative black holes
International Nuclear Information System (INIS)
In this paper we complete the program of the noncomutative geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newman-Janis algorithm in the case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.
Charged rotating noncommutative black holes
Modesto, Leonardo; Nicolini, Piero
2010-11-01
In this paper we complete the program of the noncomutative geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newman-Janis algorithm in the case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.
Charged rotating noncommutative black holes
Modesto, Leonardo
2010-01-01
In this paper we complete the program of the Noncomutative Geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newmann-Janis algorithm in case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.
Geometric inequalities for black holes
Dain, Sergio
2014-01-01
It is well known that the three parameters that characterize the Kerr black hole (mass, angular momentum and horizon area) satisfy several important inequalities. Remarkably, some of these inequalities remain valid also for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. In this article recent results in this subject are reviewed.
Black holes and cosmic censorship
International Nuclear Information System (INIS)
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 M2 greater than or equal to Q2 + P2, 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 (M2 = a2 + Q2 + P2) 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
Hayward, Sean A.; Mukohyama, Shinji; Ashworth, M. C.
1998-01-01
We consider two non-statistical definitions of entropy for dynamic (non-stationary) black holes in spherical symmetry. The first is analogous to the original Clausius definition of thermodynamic entropy: there is a first law containing an energy-supply term which equals surface gravity times a total differential. The second is Wald's Noether-charge method, adapted to dynamic black holes by using the Kodama flow. Both definitions give the same answer for Einstein gravity: one-quarter the area ...
Hawking, Stephen W.; Perry, Malcolm J.; Strominger, Andrew
2016-01-01
It has recently been shown that BMS supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft ($i.e.$ zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This paper gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that com...
Probability for primordial black holes
Bousso, R.; Hawking, S. W.
1995-11-01
We consider two quantum cosmological models with a massive scalar field: an ordinary Friedmann universe and a universe containing primordial black holes. For both models we discuss the complex solutions to the Euclidean Einstein equations. Using the probability measure obtained from the Hartle-Hawking no-boundary proposal we find that the only unsuppressed black holes start at the Planck size but can grow with the horizon scale during the roll down of the scalar field to the minimum.
Constraints on Black Hole Remnants
Giddings, S. B.
1993-01-01
One possible fate of information lost to black holes is its preservation in black hole remnants. It is argued that a type of effective field theory describes such remnants (generically referred to as informons). The general structure of such a theory is investigated and the infinite pair production problem is revisited. A toy model for remnants clarifies some of the basic issues; in particular, infinite remnant production is not suppressed simply by the large internal volumes as proposed in c...
Linezolid induced black hairy tongue
Govindan Balaji; B Maharani; Velappan Ravichandran; Thiyagarajan Parthasarathi
2014-01-01
Black hairy tongue (BHT) also called as lingua villosa nigra, is a self limiting benign condition characterized by hypertrophy and elongation of filiform papillae of tongue with brown or black discoloration. Smoking, poor oral hygiene, xerostomia, using peroxide containing mouth washes, substance abuse and drugs (steroids, methyldopa, olanzapine, etc) are the predisposing factors. However its occurrence in relation to linezolid ingestion among south Indians has not been reported in PubMed dat...
Information retrieval from black holes
Lochan, Kinjalk; Chakraborty, Sumanta; Padmanabhan, T.
2016-01-01
It is generally believed that, when matter collapses to form a black hole, the complete information about the initial state of the matter cannot be retrieved by future asymptotic observers, through local measurements. This is contrary to the expectation from a unitary evolution in quantum theory and leads to (a version of) the black hole information paradox. Classically, nothing else, apart from mass, charge and angular momentum is expected to be revealed to such asymptotic observers after th...
Black hole thermodynamics from decoherence
Guo, Xiao-Kan
2015-01-01
We present an approach to the four laws of black hole thermodynamics by utilizing the thermodynamics of quantum coherence. Firstly, Hawking effect is attributed to the decoherence of the two-mode squeezed state in a black hole spacetime. Then use is made of the relative entropy between undecohered and decohered squeezed states whose monotonicity gives the zeroth and the second law, while the first law can be obtained either by the vanishing of the first derivative of relative entropy or by st...
New regular black hole solutions
International Nuclear Information System (INIS)
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.
Frampton, Paul H.
2009-01-01
While the energy of the universe has been established to be about 0.04 baryons, 0.24 dark matter and 0.72 dark energy, the cosmological entropy is almost entirely, about $(1 - 10^{-15})$, from black holes and only $10^{-15}$ from everything else. This identification of all dark matter as black holes is natural in statistical mechanics. Cosmological history of dark matter is discussed.
Are Black Holes Elementary Particles?
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.
Evaluation of the botanical origin of black cohosh products by genetic and chemical analyses.
Masada-Atsumi, Sayaka; Kumeta, Yukie; Takahashi, Yutaka; Hakamatsuka, Takashi; Goda, Yukihiro
2014-01-01
Despite the increasing sales of black cohosh (the dried rhizome and root of Cimicifuga racemosa L.) in the world herbal market, these products have continuous adulteration issues. The botanical authenticity of the black cohosh products is the first important step for ensuring their quality, safety and efficacy. In this study, we genetically identified the botanical sources of 10 black cohosh products and 5 Cimicifuga Rhizome crude drugs of Japanese Pharmacopoeia grade, and analyzed the metabolic profiling of 25 black cohosh products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Consequently, we found that C. dahurica and possibly C. foetida are misused as sources of the black cohosh products and in some cases, the extracts of black cohosh were adulterated with the plant materials of C. dahurica. We demonstrated that these three species can be distinguished by three marker compounds in a specific mass range. These results must be helpful in establishing regulations for the safe use of the black cohosh products. PMID:24583864
The Analysis of Saccharide in Black Garlic and its Antioxidant Activity
Directory of Open Access Journals (Sweden)
Mengmeng Lei
2014-06-01
Full Text Available Black garlic was created by keeping whole ordinary garlic in a humidity controlled room at 70-80°C for 10-15 days without any artificial treatments and additives. The black garlic was extracted with 80% ethanol and concentrated to obtain black garlic ethanol extracts. The saccharides of the extracts were analyzed according to the method of Phenol Sulphate colorimetry, DNS and High Performance Liquid Chromatography (HPLC. The antioxidant capacity in vitro of the extracts was assessed by measuring the scavenging activities on 1, 1-Diphenyl-2-Picrylhydrazyl (DPPH. Drosophila melanogaster were employed to explore the effect of black garlic extract on lifespan and antioxidant index in vivo. The results showed that the total sugar content in the black garlic extracts was 55.5% including monosaccharide, disaccharide and polysaccharide, the content of reducing sugar was 25.22%. The results from this study demonstrated black garlic extracts possessed strong antioxidant capacity in vitro in a dose-dependent manner, the longevity of Drosophila melanogaster treated with black garlic extract was prolonged evidently and the content of MDA was decreased by improving SOD (including CuZn-SOD and Mn-SOD and CAT activities.
Van Herck, Walter
2009-01-01
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, arXiv:0810.4301. 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 hep-th/0702012, 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...
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.
Royzen, Ilya I
2009-01-01
Along with compacting baryon (neutron) spacing, two very important factors come into play at once: the lack of self-stabilization within a compact neutron star (NS) associated with possible black hole (BH) horizon appearance and the phase transition - color deconfinement and QCD-vacuum reconstruction - within the nuclear matter. That is why both phenomena should be taken into account side by side, as the gravitational collapse is considered. Since, under the above transition, the hadronic-phase vacuum (filled up with gluon and chiral $q\\bar q$-condensates) turns into the "empty" (perturbation) subhadronic-phase one and, thus, the corresponding (very high) pressure falls down rather abruptly, the formerly cold (degenerated) nuclear medium starts to implode into the new vacuum. If the mass of a star is sufficiently large, then this implosion produces an enormous heating, which stops only after quark-gluon plasma of a temperature about 100 MeV (or even higher) is formed to withstand the gravitational compression...
Directory of Open Access Journals (Sweden)
Nasrin Nooshfar
2011-05-01
Full Text Available Background/Objective: Development of science and"nart achieved with saving independence, separation"nclassification and studying their details. The other hand"nis combination of these to create a new world with"nwide dimensions and take a place to human needs."nMaterials and Methods: Our attempt is to make"nhealth-care places pleasant and attractive for patients."nWe offer best services, but they are not comfortable"nand happy in these places. They are afraid of the staff,"nequipment and the environment. For this purpose"nwe mixed the brightness and darkness of radiologic"nimages with white and black photographs or paintings"ncomplementary to create analog artistic images that"ncould be converted to digital printing by DICOM"ninterfaces on hard copies."nConclusion: Fear, pictures a bad memory in the"npatient's mind forever. We mixed radiology and"nimaging with photography as a science and art mixture"nto conflict with these problems, it is more effective in"nchildren who are suffering from social and known"ndiseases and can not adapt themselves with their"nsituations. This could create a good memory between"nthe human body image and sentimental experience."nIn the literature, printed radiologic images were used"nas fine art on glass and paper, metal and flowers were"nemployed to mix.* *Wim Delvoye (born 1965 ,Wervik"nand Steven N.Meyers and Merille Raikes
Bhattacharyya, Nabarun; Legin, Andrey; Papieva, Irina; Sarkar, Subrata; Kirsanov, Dmitry; Kartsova, Anna; Ghosh, Arunangshu; Bandyopadhyay, Rajib
2011-09-01
Black tea is an extensively consumed beverage worldwide with an expanding market. The final quality of black tea depends upon number of chemical compounds present in the tea. Out of these compounds, theaflavins (TF), which is responsible for astringency in black tea, plays an important role in determining the final taste of the finished black tea. The present paper reports our effort to correlate the theaflavins contents with the voltammetric and potentiometric electronic tongue (e-tongue) data. Noble metal-based electrode array has been used for collecting data though voltammetric electronic tongue where as liquid filled membrane based electrodes have been used for potentiometric electronic tongue. Black tea samples with tea taster score and biochemical results have been collected from Tea Research Association, Tocklai, India for the analysis purpose. In this paper, voltammetric and potentiometric e-tongue responses are combined to demonstrate improvement of cluster formation among tea samples with different ranges of TF values.
Tran, Minh-Tien; Kim, Ki-Seok
2010-01-01
We reveal that local interactions in graphene allow novel spin liquids between the semi-metal and antiferromagnetic Mott insulating phases, identified with algebraic spin liquid and Z$_{2}$ spin liquid, respectively. We argue that the algebraic spin liquid can be regarded as the two dimensional realization of one dimensional spin dynamics, where antiferromagnetic correlations show exactly the same power-law dependence as valence bond correlations. Nature of the Z$_{2}$ spin liquid turns out t...
Characterization of Black Carbon Mixing State Field Campaign Report
Energy Technology Data Exchange (ETDEWEB)
Sedlacek, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Davidovits, P. [Boston College, Chestnut Hill, MA (United States); Lewis, E. R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Onasch, T. B. [Aerodyne Research, Billerica, MA (United States)
2016-04-01
Interpreting the temporal relationship between the scattering and incandescence signals recorded by the Single Particle Soot Photometer (SP2), Sedlacek et al. (2012) reported that 60% of the refractory black carbon containing particles in a plume containing biomass burning tracers exhibited non-core-shell structure. Because the relationship between the rBC (refractory black carbon) incandescence and the scattering signals had not been reported in the peer-reviewed literature, and to further evaluate the initial interpretation by Sedlacek et al., a series of experiments was undertaken to investigate black carbon-containing particles of known morphology using Regal black (RB), a proxy for collapsed soot, as the light-absorbing substance to characterize this signal relationship. Particles were formed by coagulation of RB with either a solid substance (sodium chloride or ammonium sulfate) or a liquid substance (dioctyl sebacate), and by condensation with dioctyl sebacate, the latter experiment forming particles in a core-shell configuration. Each particle type experienced fragmentation (observed as negative lagtimes), and each yielded similar lagtime responses in some instances, confounding attempts to differentiate particle morphology using current SP2 lagtime analysis. SP2 operating conditions, specifically laser power and sample flow rate, which in turn affect the particle heating and dissipation rates, play an important role in the behavior of particles in the SP2, including probability of fragmentation. This behavior also depended on the morphology of the particles and on the thermochemical properties of the non-RB substance. Although these influences cannot currently be unambiguously separated, the SP2 analysis may still provide useful information on particle mixing states and black carbon particle sources. This work was communicated in a 2015 publication (Sedlacek et al. 2015)
Resource Letter BH-2: Black Holes
Gallo, Elena
2008-01-01
This resource letter is designed to guide students, educators, and researchers through (some of) the literature on black holes. Both the physics and astrophysics of black holes are discussed. Breadth has been emphasized over depth, and review articles over primary sources. We include resources ranging from non-technical discussions appropriate for broad audiences to technical reviews of current research. Topics addressed include classification of stationary solutions, perturbations and stability of black holes, numerical simulations, collisions, the production of gravity waves, black hole thermodynamics and Hawking radiation, quantum treatments of black holes, black holes in both higher and lower dimensions, and connections to nuclear and condensed matter physics. On the astronomical end, we also cover the physics of gas accretion onto black holes, relativistic jets, gravitationally red-shifted emission lines, evidence for stellar-mass black holes in binary systems and super-massive black holes at the centers...
Black holes and branes in string theory
Skenderis, K
1999-01-01
This is a set of introductory lecture notes on black holes in string theory. After reviewing some aspects of string theory such as dualities, brane solutions, supersymmetric and non-extremal intersection rules, we analyze in detail extremal and non-extremal 5d black holes. We first present the D-brane counting for extremal black holes. Then we show that 4d and 5d non-extremal black holes can be mapped to the BTZ black hole (times a compact manifold) by means of dualities. The validity of these dualities is analyzed in detail. We present an analysis of the same system in the spirit of the adS/CFT correspondence. In the ``near-horizon'' limit (which is actually a near inner-horizon limit for non-extremal black holes) the black hole reduces again to the BTZ black hole. A state counting is presented in terms of the BTZ black hole.
Kraft black liquor delivery systems
Energy Technology Data Exchange (ETDEWEB)
Adams, T.N.; Empie, H.L.; Obuskovic, N.; Spielbauer, T.M.
1990-02-01
Improvement of spray nozzles for black liquor injection into kraft recovery furnaces is expected to result from obtaining a controlled, well-defined droplet size distribution. Work this year has centered on defining the capabilities of commercial black liquor nozzles currently in use. Considerations of the observed mechanism of droplet formation suggest a major revision is needed in the theory of how droplets form from these nozzles. High resolution, high sensitivity video has been shown to be superior to flash x-ray as a technique for measuring the droplet size distribution as well as the formation history. An environmentally sound spray facility capable of spraying black liquor at temperatures up to normal firing conditions is being constructed before data acquisition continues. Preliminary correlations have been developed between liquor properties, nozzle design, and droplet size. Three aspects of nozzle design have been investigated: droplet size distribution, fluid sheet thickness, and flow and pressure drop characteristics. The standard deviation about the median droplet size for black liquor is nearly the same as the for a wide variety of other fluids and nozzle types. Preliminary correlation for fluid sheet thickness on the plate of a splashplate nozzle show the strong similarities of black liquor to other fluids. The flow and pressure drop characteristic of black liquor nozzle, follow a simple two-term relationship similar to other flow devices. This means that in routine mill operation of black liquor nozzles only the fluid acceleration in the nozzle is important, viscous losses are quiet small. 21 refs., 53 figs., 10 tabs.
International Nuclear Information System (INIS)
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.)
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.)
Magnetic oscillations in a holographic liquid
Puletti, V Giangreco M; Thorlacius, L; Zingg, T
2015-01-01
A strongly coupled 2+1 dimensional field theory at finite charge density and magnetic field is holographically modeled by an anisotropic fluid of charged spin~1/2 particles outside a dyonic black brane in 3+1 dimensional asymptotically AdS spacetime. This extends previous electron star models to include a magnetic field at finite temperature. The resulting back-reaction on the spacetime geometry and bulk gauge field gives rise to magnetic oscillations in the dual field theory, which can be directly studied without introducing probe fermions, and which differ from those predicted by Fermi liquid theory.
Time dependent black holes and scalar hair
International Nuclear Information System (INIS)
We show how to correctly account for scalar accretion onto black holes in scalar field models of dark energy by a consistent expansion in terms of a slow roll parameter. At leading order, we find an analytic solution for the scalar field within our Hubble volume, which is regular on both black hole and cosmological event horizons, and compute the back reaction of the scalar on the black hole, calculating the resulting expansion of the black hole. Our results are independent of the relative size of black hole and cosmological event horizons. We comment on the implications for more general black hole accretion, and the no hair theorems. (paper)
Implementing black hole as efficient power plant
Wei, Shao-Wen; Liu, Yu-Xiao
2016-01-01
Treating the black hole molecules as working substance and considering its phase structure, we study the black hole heat engine by a charged anti-de Sitter black hole. In the reduced temperature-entropy chart, it is found that the work, heat, and efficiency of the engine are independent of the black hole charge. Applying the Rankine cycle with or without a back pressure mechanism to the black hole heat engine, the efficiency is numerically solved. The result shows that the black hole engine w...
Radionic Non-uniform Black Strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2003-01-01
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes dilatonic black hole in the single brane limit and reduces to the Reissner-Nordstr\\"om black hole in the close limit of two-branes. The stability of solutions is demonstrated using the catastrophe theory. From ...
Black holes: the membrane paradigm
International Nuclear Information System (INIS)
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
Black holes: a slanted overview
International Nuclear Information System (INIS)
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)
Electrical resistance of diamond implanted at liquid nitrogen temperature with carbon ions
International Nuclear Information System (INIS)
Carbon ion implantation of diamond to high fluence, below the temperature at which diamond growth can occur, usually leads to black layers of high conductivity. This study shows that for a low enough temperature of the diamond during implantation, a black layer with high electrical resistance can develop. In particular, carbon ion implantation at liquid nitrogen temperature, leads to an implanted layer with electrical resistance about one million times higher than the resistance obtained for implantation at temperatures above room temperature. (author)
Macroscopic black holes, microscopic black holes and noncommutative membrane
Energy Technology Data Exchange (ETDEWEB)
Li Miao [Institute of Theoretical Physics, Academia Sinica, PO Box 2735, Beijing 100080 (China)
2004-07-21
We study the stretched membrane of a black hole as consisting of a perfect fluid. We find that the pressure of this fluid is negative and the specific heat is also negative. A surprising result is that if we are to assume the fluid to be composed of some quanta, then the dispersion relation of the fundamental quantum is E = m{sup 2}/k, with m at the scale of the Planck mass. There are two possible interpretations of this dispersion relation. One is the noncommutative spacetime on the stretched membrane and the other is that the fundamental quanta are microscopic black holes.
Macroscopic black holes, microscopic black holes and noncommutative membrane
International Nuclear Information System (INIS)
We study the stretched membrane of a black hole as consisting of a perfect fluid. We find that the pressure of this fluid is negative and the specific heat is also negative. A surprising result is that if we are to assume the fluid to be composed of some quanta, then the dispersion relation of the fundamental quantum is E = m2/k, with m at the scale of the Planck mass. There are two possible interpretations of this dispersion relation. One is the noncommutative spacetime on the stretched membrane and the other is that the fundamental quanta are microscopic black holes
Black hole mimickers: Regular versus singular behavior
International Nuclear Information System (INIS)
Black hole mimickers are possible alternatives to black holes; they would look observationally almost like black holes but would have no horizon. The properties in the near-horizon region where gravity is strong can be quite different for both types of objects, but at infinity it could be difficult to discern black holes from their mimickers. To disentangle this possible confusion, we examine the near-horizon properties, and their connection with far away asymptotic properties, of some candidates to black mimickers. We study spherically symmetric uncharged or charged but nonextremal objects, as well as spherically symmetric charged extremal objects. Within the uncharged or charged but nonextremal black hole mimickers, we study nonextremal ε-wormholes on the threshold of the formation of an event horizon, of which a subclass are called black foils, and gravastars. Within the charged extremal black hole mimickers we study extremal ε-wormholes on the threshold of the formation of an event horizon, quasi-black holes, and wormholes on the basis of quasi-black holes from Bonnor stars. We elucidate whether or not the objects belonging to these two classes remain regular in the near-horizon limit. The requirement of full regularity, i.e., finite curvature and absence of naked behavior, up to an arbitrary neighborhood of the gravitational radius of the object enables one to rule out potential mimickers in most of the cases. A list ranking the best black hole mimickers up to the worst, both nonextremal and extremal, is as follows: wormholes on the basis of extremal black holes or on the basis of quasi-black holes, quasi-black holes, wormholes on the basis of nonextremal black holes (black foils), and gravastars. Since in observational astrophysics it is difficult to find extremal configurations (the best mimickers in the ranking), whereas nonextremal configurations are really bad mimickers, the task of distinguishing black holes from their mimickers seems to be less
Edge phonons in black phosphorus.
Ribeiro, H B; Villegas, C E P; Bahamon, D A; Muraca, D; Castro Neto, A H; de Souza, E A T; Rocha, A R; Pimenta, M A; de Matos, C J S
2016-01-01
Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements. PMID:27412813
Energy on black hole spacetimes
Corichi, Alejandro
2012-01-01
We consider the issue of defining energy for test particles on a background black hole spacetime. We revisit the different notions of energy as defined by different observers. The existence of a time-like isometry allows for the notion of a total conserved energy to be well defined, and subsequently the notion of a gravitational potential energy is also meaningful. We then consider the situation in which the test particle is adsorbed by the black hole, and analyze the energetics in detail. In particular, we show that the notion of horizon energy es defined by the isolated horizons formalism provides a satisfactory notion of energy compatible with the particle's conserved energy. As another example, we comment a recent proposal to define energy of the black hole as seen by an observer at rest. This account is intended to be pedagogical and is aimed at the level of and as a complement to the standard textbooks on the subject.
Opatrný, Tomáš; Bakala, Pavel
2016-01-01
Life is dependent on the income of energy with low entropy and the disposal of energy with high entropy. On Earth, the low-entropy energy is provided by solar radiation and the high-entropy energy is disposed as infrared radiation emitted into the cold space. Here we turn the situation around and assume cosmic background radiation as the low-entropy source of energy for a planet orbiting a black hole into which the high-entropy energy is disposed. We estimate the power that can be produced by thermodynamic processes on such a planet, with a particular interest in planets orbiting a fast rotating Kerr black hole as in the science fiction movie {\\em Interstellar}. We also briefly discuss a reverse Dyson sphere absorbing cosmic background radiation from the outside and dumping waste energy to a black hole inside.
Kunduri, Hari K
2016-01-01
We present a new supersymmetric, asymptotically flat, black hole solution to five-dimensional U(1)^3-supergravity which is regular on and outside an event horizon of lens space topology L(2,1). The solution has seven independent parameters and uplifts to a new family of 1/8-supersymmetric D1-D5-P black brane solutions to Type IIB supergravity. The decoupling limit is asymptotically AdS(3) x S^3 x T^4, with a near-horizon geometry that is a twisted product of the near-horizon geometry of the extremal BTZ black hole and L(2,1) x T^4, although it is not (locally) a product space in the bulk. Nevertheless, we find that the Bekenstein-Hawking entropy agrees exactly with the Cardy formula for the degeneracy of CFT states dual to the near-horizon geometry.
International Nuclear Information System (INIS)
We study dissipative test electromagnetic fields in a black-hole background. Quantities such as surface velocity, tangential electric field, normal magnetic induction, total surface current, and conduction surface current are introduced and are shown to satisfy Ohm's law with a surface resistivity of 4π approx. = 377 ohms. Associated with these currents there exists a ''Joule heating''. These currents can exist when the black hole is inserted in an external electric circuit, but they can exist even in the absence of external currents. In particular, we study the eddy currents induced by the rotation of a black hole in an oblique uniform magnetic field, and we show how the computation of the ohmic losses allows a very simple derivation of the torque exerted on the hole
Scrambling with matrix black holes
Brady, Lucas; Sahakian, Vatche
2013-08-01
If black holes are not to be dreaded sinks of information but rather fully described by unitary evolution, they must scramble in-falling data and eventually leak it through Hawking radiation. Sekino and Susskind have conjectured that black holes are fast scramblers; they generate entanglement at a remarkably efficient rate, with the characteristic time scaling logarithmically with the entropy. In this work, we focus on Matrix theory—M-theory in the light-cone frame—and directly probe the conjecture. We develop a concrete test bed for quantum gravity using the fermionic variables of Matrix theory and show that the problem becomes that of chains of qubits with an intricate network of interactions. We demonstrate that the black hole system evolves much like a Brownian quantum circuit, with strong indications that it is indeed a fast scrambler. We also analyze the Berenstein-Maldacena-Nastase model and reach the same tentative conclusion.
Liouvillian perturbations of black holes
Couch, W. E.; Holder, C. L.
2007-10-01
We apply the well-known Kovacic algorithm to find closed form, i.e., Liouvillian solutions, to the differential equations governing perturbations of black holes. Our analysis includes the full gravitational perturbations of Schwarzschild and Kerr, the full gravitational and electromagnetic perturbations of Reissner-Nordstrom, and specialized perturbations of the Kerr-Newman geometry. We also include the extreme geometries. We find all frequencies ω, in terms of black hole parameters and an integer n, which allow Liouvillian perturbations. We display many classes of black hole parameter values and their corresponding Liouvillian perturbations, including new closed-form perturbations of Kerr and Reissner-Nordstrom. We also prove that the only type 1 Liouvillian perturbations of Schwarzschild are the known algebraically special ones and that type 2 Liouvillian solutions do not exist for extreme geometries. In cases where we do not prove the existence or nonexistence of Liouvillian perturbations we obtain sequences of Diophantine equations on which decidability rests.
Massive Black Holes and Galaxies
CERN. Geneva
2016-01-01
Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. I will discuss measurements over the last two decades, employing adaptive optics imaging and spectroscopy on large ground-based telescopes that prove the existence of such a massive black hole in the Center of our Milky Way, beyond any reasonable doubt. These data also provide key insights into its properties and environment. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of ~2000 Schwarzschild radii in 2014, promising to be a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center Black hole promise to be able to test gravity in its strong field limit.
Disrupting Entanglement of Black Holes
Leichenauer, Stefan
2014-01-01
We study entanglement in thermofield double states of strongly coupled CFTs by analyzing two-sided Reissner-Nordstrom solutions in AdS. The central object of study is the mutual information between a pair of regions, one on each asymptotic boundary of the black hole. For large regions the mutual information is positive and for small ones it vanishes; we compute the critical length scale, which goes to infinity for extremal black holes, of the transition. We also generalize the butterfly effect of Shenker and Stanford to a wide class of charged black holes, showing that mutual information is disrupted upon perturbing the system and waiting for a time of order $\\log E/\\delta E$ in units of the temperature. We conjecture that the parametric form of this timescale is universal.
Effect of Lime and Rice Husk Ash on Index Properties of Black Cotton Soil
Dilip Shrivastava*
2014-01-01
This paper present an experimental investigation, carried out to study the effects of Rice Husk Ash on index properties of black cotton soil stabilized with 5%lime.Black cotton soil blended with 5% lime are treated by mixing Rice Husk Ash in 5%, 10%, 15%, and 20% ratio by weight of dry soil as per relevant IS code of practice and tests for index properties are carried out. The results showed a marked change in index properties of soil sample. The liquid limit and plasticity in...
Control of black hole evaporation?
International Nuclear Information System (INIS)
Contradiction between Hawking's semi-classical arguments and the string theory on the evaporation of a black hole has been one of the most intriguing problems in fundamental physics. A final-state boundary condition inside the black hole was proposed by Horowitz and Maldacena to resolve this contradiction. We point out that the original Hawking effect can also be regarded as a separate boundary condition at the event horizon for this scenario. Here, we found that the change of the Hawking boundary condition may affect the information transfer from the initial collapsing matter to the outgoing Hawking radiation during the evaporation process and as a result the evaporation process itself, significantly
Asymptotic black hole quasinormal frequencies
Motl, Lubos; Neitzke, Andrew
2003-01-01
We give a new derivation of the quasinormal frequencies of Schwarzschild black holes in d greater than or equal to 4 and Reissner-Nordstrom black holes in d = 4, in the limit of infinite damping. For Schwarzschild in d greater than or equal to 4 we find that the asymptotic real part is THawkinglog(3) for scalar perturbations and for some gravitational perturbations; this confirms a result previously obtained by other means in the case d = 4. For Reissner-Nordstrom in d = 4 w...
Geometric inequalities for black holes
Energy Technology Data Exchange (ETDEWEB)
Dain, Sergio [Universidad Nacional de Cordoba (Argentina)
2013-07-01
Full text: A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities, which are valid in the dynamical and strong field regime, play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. In this talk I will review recent results in this subject. (author)
Kunduri, Hari K.; Lucietti, James
2016-01-01
We present a new supersymmetric, asymptotically flat, black hole solution to five-dimensional U(1)^3-supergravity which is regular on and outside an event horizon of lens space topology L(2,1). The solution has seven independent parameters and uplifts to a new family of 1/8-supersymmetric D1-D5-P black brane solutions to Type IIB supergravity. The decoupling limit is asymptotically AdS(3) x S^3 x T^4, with a near-horizon geometry that is a twisted product of the near-horizon geometry of the e...
Black Hole Statistics from Holography
Shepard, Peter G.
2005-01-01
We study the microstates of the ``small'' black hole in the $\\half$-BPS sector of AdS$_5\\times S^5$, the superstar of Myers and Tafjord, using the powerful holographic description provided by LLM. The system demonstrates the inherently statistical nature of black holes, with the geometry of Myer and Tafjord emerging only after averaging over an ensemble of geometries. The individual microstate geometries differ in the highly non-trivial topology of a quantum foam at their core, and the entrop...
Information Loss in Black Holes
Hawking, Stephen William
2005-01-01
The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with non-trivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.
Information loss in black holes
Hawking, S. W.
2005-10-01
The question of whether information is lost in black holes is investigated using Euclidean path integrals. The formation and evaporation of black holes is regarded as a scattering problem with all measurements being made at infinity. This seems to be well formulated only in asymptotically AdS spacetimes. The path integral over metrics with trivial topology is unitary and information preserving. On the other hand, the path integral over metrics with nontrivial topologies leads to correlation functions that decay to zero. Thus at late times only the unitary information preserving path integrals over trivial topologies will contribute. Elementary quantum gravity interactions do not lose information or quantum coherence.
Black holes and warped spacetime
International Nuclear Information System (INIS)
Black holes (BHs) and their warping effect on spacetime are described, beginning with a discussion on stellar evolution that includes white dwarfs, supernovas and neutron stars. The structure of static, rotating, and electrically charged BHs are considered, as well as the general theory of relativity, quantum mechanics, the Einstein-Rosen bridge, and wormholes in spacetime. Attention is also given to gravitational lenses, various space geometries, quasars, Seyfert galaxies, supermassive black holes, the evaporation and particle emission of BHs, and primordial BHs, including their temperature and lifetime
Black diholes in five dimensions
Teo, E
2003-01-01
Using a generalized Weyl formalism, we show how stationary, axisymmetric solutions of the four-dimensional vacuum Einstein equation can be turned into static, axisymmetric solutions of five-dimensional dilaton gravity coupled to a two-form gauge field. This procedure is then used to obtain new solutions of the latter theory describing pairs of extremal magnetic black holes with opposite charges, known as black diholes. These diholes are kept in static equilibrium by membrane-like conical singularities stretching along two different directions. We also present solutions describing diholes suspended in a background magnetic field, and with unbalanced charges.
Black Diamonds at Brane Junctions
Chamblin, Andrew; Csaki, Csaba; Erlich, Joshua; Timothy J. Hollowood
2000-01-01
We discuss the properties of black holes in brane-world scenarios where our universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane wh...
Introduction to Black Hole Evaporation
Lambert, Pierre-Henry
2013-01-01
These lecture notes are an elementary and pedagogical introduction to the black hole evaporation, based on a lecture given by the author at the Ninth Modave Summer School in Mathematical Physics and are intended for PhD students. First, quantum field theory in curved spacetime is studied and tools needed for the remaining of the course are introduced. Then quantum field theory in Rindler spacetime in 1+1 dimensions and in the spacetime of a spherically collapsing star are considered, leading to Unruh and Hawking effects, respectively. Finally some consequences such as thermodynamics of black holes and information loss paradox are discussed.
The Dilemma of the Black Intellectual.
West, Cornel
1994-01-01
Examines the problems inherent in being a black intellectual: the predicament of being caught between an insolent American society and an insouciant black community. The paper suggests various ways of understanding and transforming the problem. (GLR)
Regular Black Holes with Cosmological Constant
Institute of Scientific and Technical Information of China (English)
MO Wen-Juan; CAI Rong-Gen; SU Ru-Keng
2006-01-01
We present a class of regular black holes with cosmological constant Λ in nonlinear electrodynamics. Instead of usual singularity behind black hole horizon, all fields and curvature invariants are regular everywhere for the regular black holes. Through gauge invariant approach, the linearly dynamical stability of the regular black hole is studied. In odd-parity sector, we find that the Λ term does not appear in the master equations of perturbations, which shows that the regular black hole is stable under odd-parity perturbations. On the other hand, for the even-parity sector, the master equations are more complicated than the case without the cosmological constant. We obtain the sufficient conditions for stability of the regular black hole. We also investigate the thermodynamic properties of the regular black hole, and find that those thermodynamic quantities do not satisfy the differential form of first law of black hole thermodynamics. The reason for violating the first law is revealed.
Implementing black hole as efficient power plant
Wei, Shao-Wen
2016-01-01
Treating the black hole molecules as working substance and considering its phase structure, we study the black hole heat engine by a charged anti-de Sitter black hole. In the reduced temperature-entropy chart, it is found that the work, heat, and efficiency of the engine are independent of the black hole charge. Applying the Rankine cycle with or without a back pressure mechanism to the black hole heat engine, the efficiency is numerically solved. The result shows that the black hole engine working along the Rankine cycle with a back pressure mechanism has a higher efficiency. This provides a novel and efficient mechanism to produce the useful mechanical work with black hole, and such heat engine may act as a possible energy source for the high energy astrophysical phenomena near the black hole.
A Perspective for Assertiveness Training for Blacks
Minor, Billy Joe
1978-01-01
This article discussess assertiveness in the Black-White encounter. The author delineates the assertive options available to Blacks, distortions in interpretation of assertive messages, and strategies for more effective and efficient assertions. (Author)
Black supernovae and black holes in non-local gravity
Bambi, Cosimo; Malafarina, Daniele; Modesto, Leonardo
2016-04-01
In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certain conditions, the lifetime of our black holes exactly scales as the Hawking evaporation time.
Moodulitest komplekteeritav diivan Black = A modular sofa called Black
2007-01-01
Autor Tiina Mang pälvis diivanikomplekti Black eest Eesti Sisearhitektide Liidu 2006. a. esemepreemia. T. Mangist, objektid, kuhu on valitud T. Mangi projekteeritud mööblit, näitused. 3 värv. vaadet, foto T. Mangist
Modified dispersion relations and black hole physics
Ling, Yi; Hu, Bo; Li, Xiang
2005-01-01
A modified formulation of energy-momentum relation is proposed in the context of doubly special relativity. We investigate its impact on black hole physics. It turns out that such modification will give corrections to both the temperature and the entropy of black holes. In particular this modified dispersion relation also changes the picture of Hawking radiation greatly when the size of black holes approaching the Planck scale. It can prevent black holes from total evaporation, as a result pr...
The coalescence rates of double black holes
Belczynski, Krzysztof; Bulik, Tomasz; Dominik, Michal; Prestwich, Andrea
2011-01-01
We present the summary of the recent investigations of double black hole binaries in context of their formation and merger rates. In particular we discuss the spectrum of black hole masses, the formation scenarios in the local Universe and the estimates of detection rates for gravitational radiation detectors like LIGO and VIRGO. Our study is based on observed properties of known Galactic and extra-galactic stellar mass black holes and evolutionary predictions. We argue that the binary black ...
Black-hole formation from stellar collapse
International Nuclear Information System (INIS)
I review the end-state of massive stellar evolution, following the evolution of these massive stars from the onset of collapse through the formation of a compact remnant and the possible supernova or hypernova explosion. In particular, I concentrate on the formation of black holes from stellar collapse: the fraction of stars that form black holes, the black-hole mass distribution and the velocities these black-hole remnants may receive during their formation process
Black holes sourced by a massless scalar
Cadoni, Mariano
2015-01-01
We construct asymptotically flat black hole solutions of Einstein-scalar gravity sourced by a nontrivial scalar field with 1/r asymptotic behaviour. Near the singularity the black hole behaves as the Janis-Newmann-Winicour-Wyman solution. The hairy black hole solutions allow for a consistent thermodynamical description. At large mass they have the same thermodynamical behaviour of the Schwarzschild black hole, whereas for small masses they differ substantially from the latter.
Merging galaxies and black hole ejections
Valtonen, M. J.
1990-01-01
In mergers of galaxies their central black holes are accumulated together. Researchers show that few black hole systems arise which decay through black hole collisions and black hole ejections. The ejection statistics are calculated and compared with two observed systems where ejections have been previously suggested: double radio sources and high redshift quasars near low redshift galaxies. In both cases certain aspects of the associations are explained by the merger hypothesis.
Black Thyroid Associated with Thyroid Carcinoma
Emad Kandil; Mohamed Abdel Khalek; Haytham Alabbas; Philip Daroca; Tina Thethi; Paul Friedlander; Ryan Leblanc; Obai Abdullah; Bernard Jaffe; Byron Crawford
2010-01-01
Objective. Black thyroid is a rare pigmented change seen almost exclusively in patients upon minocycline ingestion, and the process has previously been thought to be generally benign. There have been 61 reported cases of black thyroid. We are aware of 13 cases previously reported in association with thyroid carcinoma. This paper reports six patients with black thyroid pigmentation in association with thyroid carcinoma. Design. The medical records of six patients who were diagnosed with black ...
Noncommutative geometry inspired Schwarzschild black hole
Nicolini, Piero; Smailagic, Anais; Spallucci, Euro
2005-01-01
We investigate the behavior of a noncommutative radiating Schwarzschild black hole. It is shown that coordinate noncommutativity cures usual problems encountered in the description of the terminal phase of black hole evaporation. More in detail, we find that: the evaporation end-point is a zero temperature extremal black hole even in the case of electrically neutral, non-rotating, objects; there exists a finite maximum temperature that the black hole can reach before cooling down to absolute ...
Energy conservation for dynamical black holes
Hayward, Sean A.
2004-01-01
An energy conservation law is described, expressing the increase in mass-energy of a general black hole in terms of the energy densities of the infalling matter and gravitational radiation. For a growing black hole, this first law of black-hole dynamics is equivalent to an equation of Ashtekar & Krishnan, but the new integral and differential forms are regular in the limit where the black hole ceases to grow. An effective gravitational-radiation energy tensor is obtained, providing measures o...
Supermassive Black Holes and Their Environments
Colberg, Joerg M.; Di Matteo, Tiziana
2008-01-01
We make use of the first high--resolution hydrodynamic simulations of structure formation which self-consistently follows the build up of supermassive black holes introduced in Di Matteo et al. (2007) to investigate the relation between black holes (BH), host halo and large--scale environment. There are well--defined relations between halo and black hole masses and between the activities of galactic nuclei and halo masses at low redshifts. A large fraction of black holes forms anti--hierarchi...
Black hole growth in hierarchical galaxy formation.
Malbon, R. K.; Baugh, C M; Frenk, C. S.; Lacey, C. G.
2007-01-01
We incorporate a model for black hole growth during galaxy mergers into the semi-analytical galaxy formation model based on Lambda-CDM proposed by Baugh et al. (2005). Our black hole model has one free parameter, which we set by matching the observed zeropoint of the local correlation between black hole mass and bulge luminosity. We present predictions for the evolution with redshift of the relationships between black hole mass and bulge properties. Our simulations reproduce the evolution of ...
Thermodynamic instability of doubly spinning black objects
Astefanesei, D.; Rodriguez, M.; S. Theisen
2010-01-01
We investigate the thermodynamic stability of neutral black objects with (at least) two angular momenta. We use the quasilocal formalism to compute the grand canonical potential and show that the doubly spinning black ring is thermodynamically unstable. We consider the thermodynamic instabilities of ultra-spinning black objects and point out a subtle relation between the microcanonical and grand canonical ensembles. We also find the location of the black string/membrane phases of doubly spinn...
Black humor in O.Henry's novels
Institute of Scientific and Technical Information of China (English)
冯静楠
2013-01-01
Black humor is a kind of literary style rose in American and O .Henry's novels used it to express the satire to society and show the sympathy to the lower class .The most typical works contain black humor two are The Cop and the Anthem and The Gift of the Magi.By using black humor, he created his unique endings .This article is trying to analysis the use of black humor in his novels and the effect.
Will black holes eventually engulf the universe?
Martin-Moruno, Prado; Madrid, Jose A. Jimenez; Gonzalez-Diaz, Pedro F.
2006-01-01
The Babichev-Dokuchaev-Eroshenko model for the accretion of dark energy onto black holes has been extended to deal with black holes with non-static metrics. The possibility that for an asymptotic observer a black hole with large mass will rapidly increase and eventually engulf the Universe at a finite time in the future has been studied by using reasonable values for astronomical parameters. It is concluded that such a phenomenon is forbidden for all black holes in quintessential cosmological...
Quantum Black Holes As Elementary Particles
Ha, Yuan K.
2008-01-01
Are black holes elementary particles? Are they fermions or bosons? We investigate the remarkable possibility that quantum black holes are the smallest and heaviest elementary particles. We are able to construct various fundamental quantum black holes: the spin-0, spin 1/2, spin-1, and the Planck-charge cases, using the results in general relativity. Quantum black holes in the neighborhood of the Galaxy could resolve the paradox posed by the Greisen-Zatsepin-Kuzmin limit on the energy of cosmi...
Stationary Scalar Clouds Around Rotating Black Holes
Hod, Shahar
2012-01-01
Motivated by novel results in the theory of wave dynamics in black-hole spacetimes, we analyze the dynamics of a massive scalar field surrounding a rapidly rotating Kerr black hole. In particular, we report on the existence of stationary (infinitely long-lived) regular field configurations in the background of maximally rotating black holes. The effective height of these scalar "clouds" above the central black hole is determined analytically. Our results support the possible existence of stat...
CASH AND LIQUIDITY/LIQUIDITY AND LIQUIDITY RATIO
BEATRIX LIGHEZAN BREUER; MIHAELA LESCONI FRUMUŞANU; ADELA BREUER; ANDRA MANCIU
2012-01-01
The present paper aims to present the correlation as well as the differences between liquidity/cash and liquidity ratio in terms of economic entities. Researches on this topic are based on the opinions of some specialists in accounting and in the economic-financial analysis, as well as on the national legal stipulations and the ones set out in the International Accounting Standards, the Financial report, respectively. The object of this paper is represented by the correlation between liquidit...
Directory of Open Access Journals (Sweden)
Francisco J. Luna-Vázquez
2013-11-01
Full Text Available In Mexico black cherry (Prunus serotina Ehrh. fruits are consumed fresh, dried or prepared in jam. Considering the evidence that has linked intake of fruits and vegetables rich in polyphenols to cardiovascular risk reduction, the aim of this study was to characterize the phenolic profile of black cherry fruits and to determine their antioxidant, vasorelaxant and antihypertensive effects. The proximate composition and mineral contents of these fruits were also assessed. Black cherry fruits possess a high content of phenolic compounds and display a significant antioxidant capacity. High-performance liquid chromatography/mass spectrometric analysis indicated that hyperoside, anthocyanins and chlorogenic acid were the main phenolic compounds found in these fruits. The black cherry aqueous extract elicited a concentration-dependent relaxation of aortic rings and induced a significant reduction on systolic blood pressure in L-NAME induced hypertensive rats after four weeks of treatment. Proximate analysis showed that black cherry fruits have high sugar, protein, and potassium contents. The results derived from this study indicate that black cherry fruits contain phenolic compounds which elicit significant antioxidant and antihypertensive effects. These findings suggest that these fruits might be considered as functional foods useful for the prevention and treatment of cardiovascular diseases.
Use of Non-Conventional Cell Disruption Method for Extraction of Proteins from Black Yeasts
Čolnik, Maja; Primožič, Mateja; Knez, Željko; Leitgeb, Maja
2016-01-01
The influence of pressure and treatment time on cells disruption of different black yeasts and on activities of extracted proteins using supercritical carbon dioxide process was studied. The cells of three different black yeasts Phaeotheca triangularis, Trimatostroma salinum, and Wallemia ichthyophaga were exposed to supercritical carbon dioxide (SC CO2) by varying pressure at fixed temperature (35°C). The black yeasts cell walls were disrupted, and the content of the cells was spilled into the liquid medium. The impact of SC CO2 conditions on secretion of enzymes and proteins from black yeast cells suspension was studied. The residual activity of the enzymes cellulase, β-glucosidase, α-amylase, and protease was studied by enzymatic assay. The viability of black yeast cells was determined by measuring the optical density of the cell suspension at 600 nm. The total protein concentration in the suspension was determined on UV–Vis spectrophotometer at 595 nm. The release of intracellular and extracellular products from black yeast cells was achieved. Also, the observation by an environmental scanning electron microscopy shows major morphological changes with SC CO2-treated cells. The advantages of the proposed method are in a simple use, which is also possible for heat-sensitive materials on one hand and on the other hand integration of the extraction of enzymes and their use in biocatalytical reactions.
Critical behavior of Born-Infeld dilaton black holes
Dehghani, M. H.; Sheykhi, A.; Dayyani, Z.
2016-01-01
We explore the critical behavior of (n +1 )-dimensional topological Born-Infeld-dilaton black holes in an extended phase space. We treat the cosmological constant and the Born-Infeld (BI) parameter as the thermodynamic pressure and BI vacuum polarization which can vary. We obtain thermodynamic quantities of the system such as pressure, temperature, Gibbs free energy, and investigate the behavior of these quantities. We also study the analogy of the van der Waals liquid-gas system with the Born-Infeld-dilaton black holes in canonical ensemble in which we can treat the black hole charge as a fixed external parameter. Moreover, we show that the critical values of pressure, temperature and volume are physical provided the coupling constant of dilaton gravity is less than 1 and the horizon is sphere. Finally, we calculate the critical exponents and show that although thermodynamic quantities depend on the dilaton coupling constant, BI parameter and the dimension of the spacetime, they are universal and are independent of metric parameters.
Liquid Effluent Retention Facility
Federal Laboratory Consortium — The Liquid Effluent Retention Facility (LERF) is located in the central part of the Hanford Site. LERF is permitted by the State of Washington and has three liquid...
Myers, Robert C.
1997-01-01
Recently, string theory has provided some remarkable new insights into the microphysics of black holes. I argue that a simple and important lesson is also provided with regards to the information loss paradox, namely, pure quantum states do not form black holes! Thus it seems black hole formation, as well as evaporation, must be understood within the framework of quantum decoherence.
Signatures of black holes at the LHC
Cavaglia, Marco; Godang, Romulus; Cremaldi, Lucien M.; Summers, Donald J.
2007-01-01
Signatures of black hole events at CERN's Large Hadron Collider are discussed. Event simulations are carried out with the Fortran Monte Carlo generator CATFISH. Inelasticity effects, exact field emissivities, color and charge conservation, corrections to semiclassical black hole evaporation, gravitational energy loss at formation and possibility of a black hole remnant are included in the analysis.
Black Women's Leadership: Challenges and Strategies.
Hill-Davidson, Leslie
1987-01-01
Responds to presentations made at a 1986 symposium on black women's leadership in the United States. Asserts that the symposium participants successfully celebrated black women, but few were willing to discuss the connection between systems of oppression (i.e., racial and sexist), and there was little recognition of class distinctions among black,…
Black Studies and Global Perspectives: An Essay.
Drake, St. Clair
1984-01-01
Relates the emergence of Black Studies programs in the 1960s to the interest of American Blacks in the African independence struggles. Observes a shift in Black Studies away from the militancy of its origins and calls for reconsideration of its purpose. Reviews related literature. (KH)
Compensating Scientism through "The Black Hole."
Roth, Lane
The focal image of the film "The Black Hole" functions as a visual metaphor for the sacred, order, unity, and eternal time. The black hole is a symbol that unites the antinomic pairs of conscious/unconscious, water/fire, immersion/emersion, death/rebirth, and hell/heaven. The black hole is further associated with the quest for transcendent…
Light geodesics near an evaporating black hole
Guerreiro, Thiago; Monteiro, Fernando
2015-10-01
Quantum effects imply that an infalling observer cannot cross the event horizon of an evaporating black hole, even in her proper time. The Penrose diagram of an evaporating black hole is different from the one usually reported in the literature. We show that before the observer can cross the horizon the black hole disappears. Possible observational consequences are discussed.
Dilatonic Black Holes, Naked Singularities and Strings
Cox, P. H.; B. Harms(University of Alabama); Leblanc, Y.
1992-01-01
We extend a previous calculation which treated Schwarschild black hole horizons as quantum mechanical objects to the case of a charged, dilaton black hole. We show that for a unique value of the dilaton parameter `a', which is determined by the condition of unitarity of the S matrix, black holes transform at the extremal limit into strings.
A Black Hole in Our Galactic Center
Ruiz, Michael J.
2008-01-01
An introductory approach to black holes is presented along with astronomical observational data pertaining to the presence of a supermassive black hole at the center of our galaxy. Concepts of conservation of energy and Kepler's third law are employed so students can apply formulas from their physics class to determine the mass of the black hole…
Extremal black holes in N=2 supergravity
Katmadas, S.
2011-01-01
An explanation for the entropy of black holes has been an outstanding problem in recent decades. A special case where this is possible is that of extremal black holes in N=2 supergravity in four and five dimensions. The best developed case is for black holes preserving some supersymmetry (BPS), whic
Scalar field radiation from dilatonic black holes
Gohar, H.; Saifullah, K.
2012-12-01
We study radiation of scalar particles from charged dilaton black holes. The Hamilton-Jacobi method has been used to work out the tunneling probability of outgoing particles from the event horizon of dilaton black holes. For this purpose we use WKB approximation to solve the charged Klein-Gordon equation. The procedure gives Hawking temperature for these black holes as well.
Micro black holes in the laboratory
Bleicher, Marcus; Nicolini, Piero; Sprenger, Martin; Winstanley, Elizabeth(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, United Kingdom)
2011-01-01
The possibility of creating microscopic black holes is one of the most exciting predictions for the LHC, with potentially major consequences for our current understanding of physics. We briefly review the theoretical motivation for micro black hole production, and our understanding of their subsequent evolution. Recent work on modelling the radiation from quantum-gravity-corrected black holes is also discussed.
White holes and eternal black holes
International Nuclear Information System (INIS)
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)
White holes and eternal black holes
Stephen D. H. Hsu
2010-01-01
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.
Changes in Newspaper Images of Black Americans.
Martindale, Carolyn
A study was conducted to determine whether newspaper coverage of black Americans diminished after the 1960s Civil Rights Movement and whether new images of blacks have begun to emerge in the media. Items concerning black Americans in 66 issues each of the "New York Times,""Boston Globe,""Chicago Tribune," and "Atlanta Constitution" were coded. The…
Resource Letter BH-1: Black Holes.
Detweiler, Steven
1981-01-01
Lists resources on black holes, including: (1) articles of historical interest; (2) books and journal articles on elementary expositions; (3) elementary and advanced textbooks; and (4) research articles on analytic structure of black holes, black hole dynamics, and astrophysical processes. (SK)
Black Editors' Responses to Power and Propaganda.
Kreiling, Albert
Two leading black newspapers were very outspoken during the black American's struggle for equality following the Civil War of the 1860s. The Chicago-based "Conservator" and "Appeal" actively encouraged blacks to enter the nationwide power struggle among warring interests on their own behalf, and on a cultural level they attempted to elevate the…
5D Black Holes and Matrix Strings
Dijkgraaf, R.; Verlinde, E.; Verlinde, H.
1997-01-01
We derive the world-volume theory, the (non)-extremal entropy and background geometry of black holes and black strings constructed out of the NS IIA fivebrane within the framework of matrix theory. The CFT description of strings propagating in the black hole geometry arises as an effective field theory.
Black Hole Monodromy and Conformal Field Theory
A. Castro; J.M. Lapan; A. Maloney; M.J. Rodriguez
2013-01-01
The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a nonextremal black hole, and it explains why features of the inner event h
On Quantum Contributions to Black Hole Growth
Spaans, M.
2013-01-01
The effects of Wheeler’s quantum foam on black hole growth are explored from an astrophysical per- spective. Quantum fluctuations in the form of mini (10−5 g) black holes can couple to macroscopic black holes and allow the latter to grow exponentially in mass on a time scale of 109 years. Consequent
Radionic Non-uniform Stable Black Strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2003-01-01
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.
Radionic Non-Uniform Black Strings
Tamaki, T.; Kanno, S.; Soda, J.
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.
The Black Woman Cross-Culturally.
Steady, Filomina Chioma, Ed.
This is a collection of anthropological and sociological articles on the black woman. Essays cover the experiences of black women in Africa, the Caribbean, South America, and the United States in politics, business, the community, the arts, the family, and social change. Several themes are present throughout this anthology, including black women's…
Troubling Success: Interviews with Black Female Faculty
Edwards, Nivischi N.; Beverly, Monifa Green; Alexander-Snow, Mia
2011-01-01
This study explores the complexity of success for Black female faculty members based on six Black women at a public research oriented university in the Southeast. All women shared the challenges they experience as Black female faculty members. Findings indicate that while these women seemingly have attained professional success, they are leery of…
Securitization, transparency, and liquidity
Pagano, M.; Volpin, P.
2012-01-01
We present a model in which issuers of asset backed securities choose to release coarse information to enhance the liquidity of their primary market, at the cost of reducing secondary market liquidity or even causing it to freeze. The degree of transparency is inefficiently low if the social value of secondary market liquidity exceeds its private value. We analyze various types of public intervention — mandatory transparency standards, provision of liquidity to distressed banks or secondary m...
Wang, Xin-Jiu
2004-01-01
This textbook consists of six chapters. The first chapter highlightsthe concept of liquid crystals, including chemical structure, phaseclassification, defect and texture, and continuum theory. It has beencarefully written to meet the needs of readers who do not specializein liquid crystals. The second chapter is related to the theoreticaldescription of liquid crystalline polymers, networks, and gels, whichdeals with subjects such as the formation of liquid crystallinity inthe polymer system, the phase transition and phase diagram, themolecular weight effect, chain conformation, physics proper
Scattering by regular black holes: Planar massless scalar waves impinging upon a Bardeen black hole
Macedo, Caio F B; Crispino, Luís C B
2015-01-01
Singularities are common features of general relativity black holes. However, within general relativity, one can construct black holes that present no singularities. These regular black hole solutions can be achieved by, for instance, relaxing one of the energy conditions on the stress energy tensor sourcing the black hole. Some regular black hole solutions were found in the context of non-linear electrodynamics, the Bardeen black hole being the first one proposed. In this paper, we consider a planar massless scalar wave scattered by a Bardeen black hole. We compare the scattering cross section computed using a partial-wave description with the classical geodesic scattering of a stream of null geodesics, as well as with the semi-classical glory approximation. We obtain that, for some values of the corresponding black hole charge, the scattering cross section of a Bardeen black hole has a similar interference pattern of a Reissner-Nordstr\\"om black hole.
Liquidation Triggers and the Valuation of Equity and Debt
Dan Galai; Alon Raviv; Zvi Wiener
2003-01-01
Net-worth covenants, as introduced by Black and Cox (1976), provide the firm’s bondholders with the right to force reorganization or liquidation if the value of the firm falls below a certain threshold. In the event of default, however, many bankruptcy codes stipulate an automatic stay of assets that prevent bondholders from triggering liquidation and thus impact many positive net-worth covenants. To consider this impact on a corporation’s capital structure we develop a general model of liqui...
Volonteri, Marta
2012-01-01
I briefly outline recent theoretical developments on the formation of the first massive black holes (MBHs) that may grow into the population of MBHs powering quasars and inhabiting galactic centers today. I also touch upon possible observational tests that may give insights on what the properties of the first MBHs were.
Sexuality Attitudes of Black Adults.
Timberlake, Constance A.; Carpenter, Wayne D.
1990-01-01
Assessed sexuality attitudes of black middle-class sample (N=124) concerning communication regarding sexuality information, adolescent contraception, adolescent pregnancy, nonmarital intercourse, responsibility for contraception and pregnancy, abortion, pornography, and masturbation. Results suggest that participants were well-informed, moderate,…
Close encounters of black holes
Giulini, D
2003-01-01
This is an introduction into the problem of how to set up black hole initial-data for the matter-free field equations of General Relativity. The approach is semi-pedagogical and addresses a more general audience of astrophysicists and students with no specialized training in General Relativity beyond that of an introductory lecture.
Black Holes and Exotic Spinors
Directory of Open Access Journals (Sweden)
J. M. Hoff da Silva
2016-05-01
Full Text Available Exotic spin structures are non-trivial liftings, of the orthogonal bundle to the spin bundle, on orientable manifolds that admit spin structures according to the celebrated Geroch theorem. Exotic spin structures play a role of paramount importance in different areas of physics, from quantum field theory, in particular at Planck length scales, to gravity, and in cosmological scales. Here, we introduce an in-depth panorama in this field, providing black hole physics as the fount of spacetime exoticness. Black holes are then studied as the generators of a non-trivial topology that also can correspond to some inequivalent spin structure. Moreover, we investigate exotic spinor fields in this context and the way exotic spinor fields branch new physics. We also calculate the tunneling probability of exotic fermions across a Kerr-Sen black hole, showing that the exotic term does affect the tunneling probability, altering the black hole evaporation rate. Finally we show that it complies with the Hawking temperature universal law.
Information retrieval from black holes
Lochan, Kinjalk; Padmanabhan, T
2016-01-01
It is generally believed that, when matter collapses to form a black hole, the complete information about the initial state of the matter cannot be retrieved by future asymptotic observers, through local measurements. This is contrary to the expectation from a unitary evolution in quantum theory and leads to (a version of) the black hole information paradox. Classically, nothing else, apart from mass, charge and angular momentum is expected to be revealed to such asymptotic observers after the formation of a black hole. Semi-classically, black holes evaporate after their formation through the Hawking radiation. The dominant part of the radiation is expected to be thermal and hence one cannot know anything about the initial data from the resultant radiation. However, there can be sources of distortions which make the radiation non-thermal. Although the distortions are not strong enough to make the evolution unitary, these distortions carry some part of information regarding the in-state. In this work, we show ...
Extremal Higher Spin Black Holes
Bañados, Máximo; Faraggi, Alberto; Jottar, Juan I
2015-01-01
The gauge sector of three-dimensional higher spin gravities can be formulated as a Chern-Simons theory. In this context, a higher spin black hole corresponds to a flat connection with suitable holonomy (smoothness) conditions which are consistent with the properties of a generalized thermal ensemble. Building on these ideas, we discuss a definition of black hole extremality which is appropriate to the topological character of 3d higher spin theories. Our definition can be phrased in terms of the Jordan class of the holonomy around a non-contractible (angular) cycle, and we show that it is compatible with the zero-temperature limit of smooth black hole solutions. While this notion of extremality does not require nor implies the existence of supersymmetry, we exemplify its consequences in the context of sl(3|2) + sl(3|2) Chern-Simons theory. Remarkably, while as usual not all extremal solutions preserve supersymmetries, we find that the higher spin setup allows for non-extremal supersymmetric black hole solutio...
Begelman, Mitchell C
2012-01-01
We propose that the growth of supermassive black holes is associated mainly with brief episodes of highly super-Eddington infall of gas ("hyperaccretion"). This gas is not swallowed in real time, but forms an envelope of matter around the black hole that can be swallowed gradually, over a much longer timescale. However, only a small fraction of the black hole mass can be stored in the envelope at any one time. We argue that any infalling matter above a few per cent of the hole's mass is ejected as a result of the plunge in opacity at temperatures below a few thousand degrees K, corresponding to the Hayashi track. The speed of ejection of this matter, compared to the velocity dispersion (sigma) of the host galaxy's core, determines whether the ejected matter is lost forever or returns eventually to rejoin the envelope, from which it can be ultimately accreted. The threshold between matter recycling and permanent loss defines a relationship between the maximum black hole mass and sigma that resembles the empiri...
Gravitating Disks Around Black Holes
Czech Academy of Sciences Publication Activity Database
Karas, Vladimír; Šubr, Ladislav
Cambridge : Cambridge University Press, 2010 - (Peterson, B.), s. 332-332 ISBN 978-0-521-76502-2. - (IAU Symposium Proceedings Series. 267). [Symposium of the International Astronomical Union /267./. Rio de Janeiro (BR), 10.08.2009-14.08.2009] Institutional research plan: CEZ:AV0Z10030501 Keywords : accretion disks * gravitation * black hole physics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Energy Technology Data Exchange (ETDEWEB)
Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-10-06
Pinhole photography has made major contributions to astrophysics through the use of “coded apertures”. Coded apertures were instrumental in locating gamma-ray bursts and proving that they originate in faraway galaxies, some from the birth of black holes from the first stars that formed just after the big bang.
Quantum Geometry and Black Holes
Ashtekar, Abhay; Ashtekar, Abhay; Krasnov, Kirill
1998-01-01
Non-perturbative quantum general relativity provides a possible framework to analyze issues related to black hole thermodynamics from a fundamental perspective. A pedagogical account of the recent developments in this area is given. The emphasis is on the conceptual and structural issues rather than technical subtleties. The article is addressed to post-graduate students and beginning researchers.
Android for the Beaglebone Black
Henderson, Andrew
2015-01-01
If you are an Android app developer who wants to experiment with the hardware capabilities of the BeagleBone Black platform, then this book is ideal for you. You are expected to have basic knowledge of developing Android apps but no prior hardware experience is required.
L. Selbmann; G.S. de Hoog; L. Zucconi; D. Isola; S. Onofri
2014-01-01
Black yeasts have already been known since the end of the nineteenth century, but for a number of reasons, only few workers were familiar with them. That was since recently, until the wealth of biodiversity, stunning ecologies and potential applications have become apparent. Some remote and extreme
Black phosphorus nonvolatile transistor memory.
Lee, Dain; Choi, Yongsuk; Hwang, Euyheon; Kang, Moon Sung; Lee, Seungwoo; Cho, Jeong Ho
2016-04-28
We demonstrated nanofloating gate transistor memory devices (NFGTMs) using mechanically-exfoliated few-layered black phosphorus (BP) channels and gold nanoparticle (AuNPs) charge trapping layers. The resulting BP-NFGTMs exhibited excellent memory performances, including the five-level data storage, large memory window (58.2 V), stable retention (10(4) s), and cyclic endurance (1000 cycles). PMID:27074903
Scalar fields versus black holes
International Nuclear Information System (INIS)
It is shown that if a body is endowed with a scalar charge, the event horizon associated with the modified Schwarzchild solution is reduced to a point, this avoiding the black holes formation. The discussion is restricted to ordinary scalar fields and conformally invariant scalar fields, respectively. (authors)
Black diamonds at brane junctions
Chamblin, Andrew; Csáki, Csaba; Erlich, Joshua; Hollowood, Timothy J.
2000-08-01
We discuss the properties of black holes in brane-world scenarios where our Universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane which will induce on the brane-world the Schwarzschild solution. This exact solution is unstable to the Gregory-Laflamme instability, whereby long-wavelength perturbations cause the extended horizon to fragment. We therefore argue that at late times a non-rotating uncharged black hole in the brane-world is described by a deformed event horizon in p+4 dimensions which will induce, to good approximation, the Schwarzschild solution in the four-dimensional brane world. When p=2, this deformed horizon resembles a black diamond and more generally for p>2, a polyhedron.
Black Diamonds at Brane Junctions
Chamblin, A; Erlich, J; Hollowood, Timothy J; Chamblin, Andrew; Csaki, Csaba; Erlich, Joshua; Hollowood, Timothy J.
2000-01-01
We discuss the properties of black holes in brane-world scenarios where ouruniverse is viewed as a four-dimensional sub-manifold of somehigher-dimensional spacetime. We consider in detail such a model wherefour-dimensional spacetime lies at the junction of several domain walls in ahigher dimensional anti-de Sitter spacetime. In this model there may be anynumber p of infinitely large extra dimensions transverse to the brane-world. Wepresent an exact solution describing a black p-brane which will induce on thebrane-world the Schwarzschild solution. This exact solution is unstable to theGregory-Laflamme instability, whereby long-wavelength perturbations cause theextended horizon to fragment. We therefore argue that at late times anon-rotating uncharged black hole in the brane-world is described by a deformedevent horizon in p+4 dimensions which will induce, to good approximation, theSchwarzschild solution in the four-dimensional brane world. When p=2, thisdeformed horizon resembles a black diamond and more gener...
Black diamonds at brane junctions
International Nuclear Information System (INIS)
We discuss the properties of black holes in brane-world scenarios where our Universe is viewed as a four-dimensional sub-manifold of some higher-dimensional spacetime. We consider in detail such a model where four-dimensional spacetime lies at the junction of several domain walls in a higher dimensional anti-de Sitter spacetime. In this model there may be any number p of infinitely large extra dimensions transverse to the brane-world. We present an exact solution describing a black p-brane which will induce on the brane-world the Schwarzschild solution. This exact solution is unstable to the Gregory-Laflamme instability, whereby long-wavelength perturbations cause the extended horizon to fragment. We therefore argue that at late times a non-rotating uncharged black hole in the brane-world is described by a deformed event horizon in p+4 dimensions which will induce, to good approximation, the Schwarzschild solution in the four-dimensional brane world. When p=2, this deformed horizon resembles a black diamond and more generally for p>2, a polyhedron. (c) 2000 The American Physical Society
Black Physical Educators and Utilitarianism.
Coursey, Leon N.
The contributions of black professional personnel to the field of physical education are enumerated and described. The careers of Anita J. Turner, Edwin B. Henderson, and Albert J. Overly in particular are examined. The ability of a minority group to provide significant leadership in an educational field is discussed, and the challenge still…
Czech Academy of Sciences Publication Activity Database
Pravda, Vojtěch; Pravdová, Alena
2005-01-01
Roč. 37, č. 7 (2005), s. 1277-1287. ISSN 0001-7701 R&D Projects: GA ČR GP202/03/P017; GA AV ČR KJB1019403 Institutional research plan: CEZ:AV0Z10190503 Keywords : algebraic classification * Petrov classification * black ring Subject RIV: BA - General Mathematics Impact factor: 1.550, year: 2005
Magnetospheres around rotating black holes
Czech Academy of Sciences Publication Activity Database
Dovčiak, Michal; Karas, V.
Singapor: World Scientific Publishing Co., 2003 - (Ruffini, R.; Sigismondi, C.), s. 288-295 [Nonlinear gravitodynamics. Rome (IT), 29.06.1998-04.07.1998] Institutional research plan: CEZ:AV0Z1003909 Keywords : black holes * general relativity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
The External Effects of Black-Male Incarceration on Black Females
Stéphane Mechoulan
2006-01-01
We examine how the rising incarceration of Black men and the sex ratio imbalance it induces shapes young Black women’s behavior during their late teens and early twenties. Combining data from the BJS and the CPS to match incarceration rates with individual observations, we show that Black male incarceration lowers the odds of non-marital teenage fertility and increases single Black women’s school attainment and early employment. We do not find consistent evidence that high Black male incarcer...
Liquid--liquid contact in vapor explosion
International Nuclear Information System (INIS)
The contact of two liquid materials, one of which is at a temperature substantially above the boiling point of the other, can lead to fast energy conversion and a subsequent shock wave. This well-known phenomenon is called a ''vapor explosion.'' One method of producing intimate, liquid--liquid contact (which is known to be a necessary condition for vapor explosion) is a shock tube configuration. Such experiments in which water was impacted upon molten aluminum showed that very high pressures, even larger than the thermodynamic critical pressure, could occur. The mechanism by which such sharp pressure pulses are generated is not yet clear. In this experiment cold liquids (Freon-11, Freon-22, water, or butanol) were impacted upon various hot materials (mineral oil, silicone oil, water, mercury, molten Wood's metal or molten salt mixture). The main conclusion from the experimental study is that hydrodynamic effects may be very significant in any shock tube analyses, especially when multiple interactions are observed. A theoretical study was performed to check the possibility of vapor film squeezing (between a drop in film boiling and a surface) as a controlling mechanism for making liquid--liquid contact. Using experimental data, the film thickness was calculated and it was found to be too thick for any conceivable film rupture mechanism. It was suggested that the coalescence is a two-stage process, in which the controlling stage depends mainly on temperature and surface properties and can be described as the ability of cold liquid to spread on a hot surface
Extremal higher spin black holes
Bañados, Máximo; Castro, Alejandra; Faraggi, Alberto; Jottar, Juan I.
2016-04-01
The gauge sector of three-dimensional higher spin gravities can be formulated as a Chern-Simons theory. In this context, a higher spin black hole corresponds to a flat connection with suitable holonomy (smoothness) conditions which are consistent with the properties of a generalized thermal ensemble. Building on these ideas, we discuss a definition of black hole extremality which is appropriate to the topological character of 3 d higher spin theories. Our definition can be phrased in terms of the Jordan class of the holonomy around a non-contractible (angular) cycle, and we show that it is compatible with the zero-temperature limit of smooth black hole solutions. While this notion of extremality does not require supersymmetry, we exemplify its consequences in the context of sl(3|2) ⊕ sl(3|2) Chern-Simons theory and show that, as usual, not all extremal solutions preserve supersymmetries. Remarkably, we find in addition that the higher spin setup allows for non-extremal supersymmetric black hole solutions. Furthermore, we discuss our results from the perspective of the holographic duality between sl(3|2) ⊕ sl(3|2) Chern-Simons theory and two-dimensional CFTs with W (3|2) symmetry, the simplest higher spin extension of the N = 2 super-Virasoro algebra. In particular, we compute W (3|2) BPS bounds at the full quantum level, and relate their semiclassical limit to extremal black hole or conical defect solutions in the 3 d bulk. Along the way, we discuss the role of the spectral flow automorphism and provide a conjecture for the form of the semiclassical BPS bounds in general N = 2 two-dimensional CFTs with extended symmetry algebras.
Gamma ray bursts of black hole universe
Zhang, T. X.
2015-07-01
Slightly modifying the standard big bang theory, Zhang recently developed a new cosmological model called black hole universe, which has only a single postulate but is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain existing observations of the universe. In the previous studies, we have explained the origin, structure, evolution, expansion, cosmic microwave background radiation, quasar, and acceleration of 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 study investigates gamma ray bursts of black hole universe and provides an alternative explanation for the energy and spectrum measurements of gamma ray bursts according to the black hole universe model. The results indicate that gamma ray bursts can be understood as emissions of dynamic star-like black holes. A black hole, when it accretes its star or merges with another black hole, becomes dynamic. A dynamic black hole has a broken event horizon and thus cannot hold the inside hot (or high-frequency) blackbody radiation, which flows or leaks out and produces a GRB. A star when it collapses into its core black hole produces a long GRB and releases the gravitational potential energy of the star as gamma rays. A black hole that merges with another black hole produces a short GRB and releases a part of their blackbody radiation as gamma rays. The amount of energy obtained from the emissions of dynamic star-like black holes are consistent with the measurements of energy from GRBs. The GRB energy spectra derived from this new emission mechanism are also consistent with the measurements.
Stationary Scalar Clouds Around Rotating Black Holes
Hod, Shahar
2012-01-01
Motivated by novel results in the theory of wave dynamics in black-hole spacetimes, we analyze the dynamics of a massive scalar field surrounding a rapidly rotating Kerr black hole. In particular, we report on the existence of stationary (infinitely long-lived) regular field configurations in the background of maximally rotating black holes. The effective height of these scalar "clouds" above the central black hole is determined analytically. Our results support the possible existence of stationary scalar field dark matter distributions surrounding rapidly rotating black holes.
Toroidal Horizons in Binary Black Hole Mergers
Bohn, Andy; Kidder, Lawrence E.; Teukolsky, Saul A.
2016-01-01
We find the first binary black hole event horizon with a toroidal topology. It had been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology, but such a phase has never been seen prior to this work. In all previous binary black hole simulations, in the coordinate slicing used to evolve the black holes, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. ...
Moving black holes via singularity excision
International Nuclear Information System (INIS)
We present a singularity excision algorithm appropriate for numerical simulations of black holes moving throughout the computational domain. The method is an extension of the excision procedure previously used to obtain stable simulations of single, non-moving black holes. The excision procedure also shares elements used in recent work to study the dynamics of a scalar field in the background of a single, boosted black hole. The excision method is tested with single black-hole evolutions using a coordinate system in which the coordinate location of the black hole, and thus the excision boundary, moves throughout the computational domain
Black holes under external inﬂuence
Indian Academy of Sciences (India)
Jiří Bičák
2000-10-01
The work on black holes immersed in external ﬁelds is reviewed in both test-ﬁeld approximation and within exact solutions. In particular we pay attention to the effect of the expulsion of the ﬂux of external ﬁelds across charged and rotating black holes which are approaching extremal states. Recently this effect has been shown to occur for black hole solutions in string theory. We also discuss black holes surrounded by rings and disks and rotating black holes accelerated by strings.
Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X.; Li, Ju
2013-04-01
The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ~10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability.
Amarasekara, Ananda S
2016-05-25
Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition. PMID:27175515
Liquid wastes processing device
International Nuclear Information System (INIS)
Purpose: To enable safety and easy evaporation of liquid components in contaminated radioactive liquid wastes, as well as to recover the cleaned-up vapors by way of distillation into liquid components. Constitution: After supplying neutralized radioactive liquid wastes into an evaporator, a vertical moving rack is adjusted so as to suck the contaminated airs in a glove box. The liquid wastes are evaporated by a heater and the vapors are cleaned up in an inclined filter element. Further, the cleaned up vapors are formed into liquid in a water cooled cooling cylinder and then introduced to a gas phase separation and liquid collection device. While on the other hand, gases are sent from a gas outlet through a vent pipe to a suction pump and discharged therefrom into a simple glove box. (Horiuchi, T.)
Black Holes Shed Light on Galaxy Formation
2000-01-01
This videotape is comprised of several segments of animations on black holes and galaxy formation, and several segments of an interview with Dr. John Kormendy. The animation segments are: (1) a super massive black hole, (2) Centarus A active black hole found in a collision, (3) galaxy NGC-4261 (active black hole and jet model), (4) galaxy M-32 (orbits of stars are effected by the gravity of the black hole), (5) galaxy M-37 (motion of stars increases as mass of black hole increases), (6) Birth of active galactic nuclei, (7) the collision of two galaxy leads to merger of the black holes, (8) Centarus A and simulation of the collision of 2 galaxies. There are also several segments of an interview with John Kormendy. In these segments he discusses the two most important aspects of his recent black hole work: (1) the correlations between galaxies speed and the mass of the black holes, and (2) the existence of black holes and galactic formation. He also discusses the importance of the Hubble Space Telescope and the Space Telescope Imaging Spectrograph to the study of black holes. He also shows the methodology of processing images from the spectrograph in his office.
Chandra Catches "Piranha" Black Holes
2007-07-01
Supermassive black holes have been discovered to grow more rapidly in young galaxy clusters, according to new results from NASA's Chandra X-ray Observatory. These "fast-track" supermassive black holes can have a big influence on the galaxies and clusters that they live in. Using Chandra, scientists surveyed a sample of clusters and counted the fraction of galaxies with rapidly growing supermassive black holes, known as active galactic nuclei (or AGN). The data show, for the first time, that younger, more distant galaxy clusters contained far more AGN than older, nearby ones. Galaxy clusters are some of the largest structures in the Universe, consisting of many individual galaxies, a few of which contain AGN. Earlier in the history of the universe, these galaxies contained a lot more gas for star formation and black hole growth than galaxies in clusters do today. This fuel allows the young cluster black holes to grow much more rapidly than their counterparts in nearby clusters. Illustration of Active Galactic Nucleus Illustration of Active Galactic Nucleus "The black holes in these early clusters are like piranha in a very well-fed aquarium," said Jason Eastman of Ohio State University (OSU) and first author of this study. "It's not that they beat out each other for food, rather there was so much that all of the piranha were able to really thrive and grow quickly." The team used Chandra to determine the fraction of AGN in four different galaxy clusters at large distances, when the Universe was about 58% of its current age. Then they compared this value to the fraction found in more nearby clusters, those about 82% of the Universe's current age. The result was the more distant clusters contained about 20 times more AGN than the less distant sample. AGN outside clusters are also more common when the Universe is younger, but only by factors of two or three over the same age span. "It's been predicted that there would be fast-track black holes in clusters, but we never
Charged rotating black holes at large D
Tanabe, Kentaro
2016-01-01
We study odd dimensional charged equally rotating black holes in the Einstein-Maxwell theory with/without a cosmological constant by using the large D expansion method, where D is a spacetime dimension. Solving the Einstein-Maxwell equations in the 1/D expansion we obtain the large D effective equations for charged equally rotating black holes. The effective equations describe the nonlinear dynamics of charged equally rotating black holes. Especially the perturbation analysis of the effective equations gives analytic formula for quasinormal mode frequencies, and we can show charged equally rotating black holes have instabilities. As one interesting feature of instabilities, we observe that the ultraspinning instability of neutral equally rotating black holes in de Sitter is connected with the instability of de Sitter Reissner-Nordstrom black hole in a rotation-charge plane of the solution parameter space. So these instabilities have same origin as dynamical properties of charged rotating black holes. We also ...
Quantum information erasure inside black holes
Lowe, David A.; Thorlacius, Larus
2015-12-01
An effective field theory for infalling observers in the vicinity of a quasi-static black hole is given in terms of a freely falling lattice discretization. The lattice model successfully reproduces the thermal spectrum of outgoing Hawking radiation, as was shown by Corley and Jacobson, but can also be used to model observations made by a typical low-energy observer who enters the black hole in free fall at a prescribed time. The explicit short distance cutoff ensures that, from the viewpoint of the infalling observer, any quantum information that entered the black hole more than a scrambling time earlier has been erased by the black hole singularity. This property, combined with the requirement that outside observers need at least of order the scrambling time to extract quantum information from the black hole, ensures that a typical infalling observer does not encounter drama upon crossing the black hole horizon in a theory where black hole information is preserved for asymptotic observers.
Quasistars: Accreting black holes inside massive envelopes
Begelman, Mitchell C; Armitage, Philip J
2007-01-01
We study the structure and evolution of "quasistars," accreting black holes embedded within massive hydrostatic gaseous envelopes. These configurations may model the early growth of supermassive black hole seeds. The accretion rate onto the black hole adjusts so that the luminosity carried by the convective envelope equals the Eddington limit for the total mass. This greatly exceeds the Eddington limit for the black hole mass alone, leading to rapid growth of the black hole. We use analytic models and numerical stellar structure calculations to study the structure and evolution of quasistars. We derive analytically the scaling of the photospheric temperature with the black hole mass and envelope mass, and show that it decreases with time as the black hole mass increases. Once the photospheric temperature becomes lower than 10000 K, the photospheric opacity drops precipitously and the photospheric temperature hits a limiting value, analogous to the Hayashi track for red giants and protostars, below which no hy...
From Schwinger Balls to Black Holes
Allahbakhshi, Davood
2016-01-01
We have shown intriguing similarities between Schwinger balls and black holes. By considering black hole as a gravitational Schwinger ball, we have derived the Bekenstein-Hawking entropy and the first law of black hole thermodynamics as a direct result of the inverse area dependence of the gravitational force. It is also shown that the Planck length is nothing but the gravitational Schwinger length. The relation between the mass and the radius of the black hole is derived by considering the black hole as a Schwinger ball of gravitons. We show how the evolution of the entanglement entropy of the black hole, as Page introduced many years ago, can be obtained by including gravitons in the black hole's evaporation process and using a deformed EPR mechanism. Also this deformed EPR mechanism can solve the information paradox. We show how naive simultaneous usage of Page's argument and equivalence principle leads to firewall problem.
Quantum information erasure inside black holes
Lowe, David A
2015-01-01
An effective field theory for infalling observers in the vicinity of a quasi-static black hole is given in terms of a freely falling lattice discretization. The lattice model successfully reproduces the thermal spectrum of outgoing Hawking radiation, as was shown by Corley and Jacobson, but can also be used to model observations made by a typical low-energy observer who enters the black hole in free fall at a prescribed time. The explicit short distance cutoff ensures that, from the viewpoint of the infalling observer, any quantum information that entered the black hole more than a scrambling time earlier has been erased by the black hole singularity. This property, combined with the requirement that outside observers need at least of order the scrambling time to extract quantum information from the black hole, ensures that a typical infalling observer does not encounter drama upon crossing the black hole horizon in a theory where black hole information is preserved for asymptotic observers.
Morris, B. G.
1986-01-01
Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.
Maxwell's equal-area law for Gauss-Bonnet Anti-de Sitter black holes
Belhaj, A; Moumni, H El; Masmar, K; Sedra, M B
2014-01-01
Interpreting the cosmological constant \\Lambda as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume, we study the Maxwell's equal area law of higher dimensional Gauss-Bonnet-AdS black holes in extended space. These black hole solutions critically behave like Van der Waals systems. It has been realized that below the critical temperature T_c the stable equilibrium is violated. We show through numerical calculations that the critical behaviors for the uncharged black holes only appear in d=5. For the charged case, we analyse solutions in d = 5 and d = 6 separately and find that, up to some constrains, the critical behaviors only appear in the spherical topology. Using the Maxwell's construction, we also find the isobar line for which the liquid-gas-like phases coexist.
Could supermassive black holes be quintessential primordial black holes?
International Nuclear Information System (INIS)
There is growing observational evidence for a population of supermassive black holes (SMBHs) in galactic bulges. We examine in detail the conditions under which these black holes must have originated from primordial black holes (PBHs). We consider the merging and accretion history experienced by SMBHs to find that, whereas it is possible that they were formed by purely astrophysical processes, this is unlikely and most probably a population of primordial progenitors is necessary. We identify the mass distribution and comoving density of this population and then propose a cosmological scenario producing PBHs with the right properties. Although this is not essential we consider PBHs produced at the end of a period of inflation with a blue spectrum of fluctuations. We constrain the value of the spectral tilt in order to obtain the required PBH comoving density. We then assume that PBHs grow by accreting quintessence, showing that their mass scales like the horizon mass while the quintessence field itself is scaling. We find that if scaling is broken just before nucleosynthesis (as is the case with some attractive nonminimally coupled models) we obtain the appropriate PBH mass distribution. Hawking evaporation is negligible in most cases, but we also discuss situations in which the interplay of accretion and evaporation is relevant
Black supernovae and black holes in non-local gravity
Bambi, Cosimo; Modesto, Leonardo
2016-01-01
In a previous paper, we studied the interior solution of a collapsing body in a non-local theory of gravity super-renormalizable at the quantum level. We found that the classical singularity is replaced by a bounce, after which the body starts expanding. A black hole, strictly speaking, never forms. The gravitational collapse does not create an event horizon but only an apparent one for a finite time. In this paper, we solve the equations of motion assuming that the exterior solution is static. With such an assumption, we are able to reconstruct the solution in the whole spacetime, namely in both the exterior and interior regions. Now the gravitational collapse creates an event horizon in a finite comoving time, but the central singularity is approached in an infinite time. We argue that these black holes should be unstable, providing a link between the scenarios with and without black holes. Indeed, we find a non catastrophic ghost-instability of the metric in the exterior region. Interestingly, under certai...
The phase structure of higher-dimensional black rings and black holes
International Nuclear Information System (INIS)
We construct an approximate solution for an asymptotically flat, neutral, thin rotating black ring in any dimension D ≥ 5 by matching the near-horizon solution for a bent boosted black string, to a linearized gravity solution away from the horizon. The rotating black ring solution has a regular horizon of topology S1 x SD-3 and incorporates the balancing condition of the ring as a zero-tension condition. For D = 5 our method reproduces the thin ring limit of the exact black ring solution. For D ≥ 6 we show that the black ring has a higher entropy than the Myers-Perry black hole in the ultra-spinning regime. By exploiting the correspondence between ultra-spinning black holes and black membranes on a two-torus, we take steps towards qualitatively completing the phase diagram of rotating blackfolds with a single angular momentum. We are led to propose a connection between MP black holes and black rings, and between MP black holes and black Saturns, through merger transitions involving two kinds of 'pinched' black holes. More generally, the analogy suggests an infinite number of pinched black holes of spherical topology leading to a complicated pattern of connections and mergers between phases
Wang, Xiaojun; Wu, Long; Cao, Jiaqi; Hong, Xincheng; Ye, Rui; Chen, Weiji; Yuan, Ting
2016-07-01
A novel, simple and rapid method based on magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction (MEA-IL-DLLME) followed by graphite furnace atomic absorption spectrometry (GFAAS) determination was established for the speciation of selenium in various food and beverage samples. In the procedure, a special magnetic effervescent tablet containing CO2 sources (sodium carbonate and sodium dihydrogenphosphate), ionic liquids and Fe3O4 magnetic nanoparticles (MNPs) was used to combine extractant dispersion and magnetic recovery procedures into a single step. The parameters influencing the microextraction efficiency, such as pH of the sample solution, volume of ionic liquid, amount of MNPs, concentration of the chelating agent, salt effect and matrix effect were investigated and optimised. Under the optimised conditions, the limits of detection (LODs) for Se(IV) were 0.021 μg l(-)(1) and the linear dynamic range was 0.05-5.0 μg l(-)(1). The relative standard deviation for seven replicate measurements of 1.0 μg l(-)(1) of Se(IV) was 2.9%. The accuracy of the developed method was evaluated by analysis of the standard reference materials (GBW10016 tea, GBW10017 milk powder, GBW10043 Liaoning rice, GBW10046 Henan wheat, GBW10048 celery). The proposed method was successfully applied to food and beverage samples including black tea, milk powder, mushroom, soybean, bamboo shoots, energy drink, bottled water, carbonated drink and mineral water for the speciation of Se(IV) and Se(VI) with satisfactory relative recoveries (92.0-108.1%). PMID:27181611
Fan, Zhong-Ying
2016-01-01
In this paper, we consider Einstein gravity coupled to a Proca field, either minimally or non-minimally, together with a vector potential of the type $V=2\\Lambda_0+ m^2 A^2/2 + \\gamma_4 A^4$. For a simpler non-minimally coupled theory with $\\Lambda_0=m=\\gamma_4=0$, we obtain both extremal and non-extremal black hole solutions that are asymptotic to Minkowski space-times. We study the global properties of the solutions and derive the first law of thermodynamics using Wald formalism. We find that the thermodynamical first laws of the extremal black holes are modified by a one form associated with the Proca. In particular, due to the existence of the non-minimal coupling, the Proca forms thermodynamic conjugates with the graviton mode and partly contributes to the one form modifying the first laws. For a minimally coupled theory with $\\Lambda_0\