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Sample records for black body absorber

  1. Quasinormal modes of black holes absorbing dark energy

    OpenAIRE

    He, Xi; Bin WANG; Wu, Shao-Feng; Lin, Chi-Yong

    2008-01-01

    We study perturbations of black holes absorbing dark energy. Due to the accretion of dark energy, the black hole mass changes. We observe distinct perturbation behaviors for absorption of different forms of dark energy into the black holes. This provides the possibility of extracting information whether dark energy lies above or below the cosmological constant boundary $w=-1$. In particular, we find in the late time tail analysis that, differently from the other dark energy models, the accret...

  2. Black phosphorus saturable absorber for ultrashort pulse generation

    Energy Technology Data Exchange (ETDEWEB)

    Sotor, J., E-mail: jaroslaw.sotor@pwr.edu.pl; Sobon, G.; Abramski, K. M. [Laser and Fiber Electronics Group, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, Wroclaw 50-370 (Poland); Macherzynski, W.; Paletko, P. [Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, Wroclaw 50-372 (Poland)

    2015-08-03

    Low-dimensional materials, due to their unique and versatile properties, are very interesting for numerous applications in electronics and optoelectronics. Recently rediscovered black phosphorus, with a graphite-like layered structure, can be effectively exfoliated up to the single atomic layer called phosphorene. Contrary to graphene, it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, black phosphorus is now intensively investigated and can complement or replace graphene in various photonics and electronics applications. Here, we demonstrate that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation. The mechanically exfoliated ∼300 nm thick layers of black phosphorus were transferred onto the fiber core, and under pulsed excitation at 1560 nm wavelength, its transmission increases by 4.6%. We have demonstrated that the saturable absorption of black phosphorus is polarization sensitive. The fabricated device was used to mode-lock an Er-doped fiber laser. The generated optical solitons with the 10.2 nm bandwidth and 272 fs duration were centered at 1550 nm. The obtained results unambiguously show that black phosphorus can be effectively used for ultrashort pulse generation with performances similar or even better than currently used graphene or carbon nanotubes. This application of black phosphorus proves its great potential to future practical use in photonics.

  3. Black phosphorus saturable absorber for ultrashort pulse generation

    International Nuclear Information System (INIS)

    Low-dimensional materials, due to their unique and versatile properties, are very interesting for numerous applications in electronics and optoelectronics. Recently rediscovered black phosphorus, with a graphite-like layered structure, can be effectively exfoliated up to the single atomic layer called phosphorene. Contrary to graphene, it possesses a direct band gap controllable by the number of stacked atomic layers. For those reasons, black phosphorus is now intensively investigated and can complement or replace graphene in various photonics and electronics applications. Here, we demonstrate that black phosphorus can serve as a broadband saturable absorber and can be used for ultrashort optical pulse generation. The mechanically exfoliated ∼300 nm thick layers of black phosphorus were transferred onto the fiber core, and under pulsed excitation at 1560 nm wavelength, its transmission increases by 4.6%. We have demonstrated that the saturable absorption of black phosphorus is polarization sensitive. The fabricated device was used to mode-lock an Er-doped fiber laser. The generated optical solitons with the 10.2 nm bandwidth and 272 fs duration were centered at 1550 nm. The obtained results unambiguously show that black phosphorus can be effectively used for ultrashort pulse generation with performances similar or even better than currently used graphene or carbon nanotubes. This application of black phosphorus proves its great potential to future practical use in photonics

  4. Quasinormal modes of black holes absorbing dark energy

    International Nuclear Information System (INIS)

    We study perturbations of black holes absorbing dark energy. Due to the accretion of dark energy, the black hole mass changes. We observe distinct perturbation behaviors for absorption of different forms of dark energy onto the black holes. This provides the possibility of extracting information whether dark energy lies above or below the cosmological constant boundary w=-1. In particular, we find in the late time tail analysis that, differently from the other dark energy models, the accretion of phantom energy exhibits a growing mode in the perturbation tail. The instability behavior found in this work is consistent with the Big Rip scenario, in which all of the bound objects are torn apart with the presence of the phantom dark energy

  5. Destroying black holes with test bodies

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Ted [Center for Fundamental Physics, University of Maryland, College Park, MD 20742-4111 (United States); Sotiriou, Thomas P, E-mail: jacobson@umd.ed, E-mail: T.Sotiriou@damtp.cam.ac.u [Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

    2010-04-01

    If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.

  6. Destroying black holes with test bodies

    International Nuclear Information System (INIS)

    If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.

  7. Enhanced performance of VOx-based bolometer using patterned gold black absorber

    Science.gov (United States)

    Smith, Evan M.; Panjwani, Deep; Ginn, James; Warren, Andrew; Long, Christopher; Figuieredo, Pedro; Smith, Christian; Perlstein, Joshua; Walter, Nick; Hirschmugl, Carol; Peale, Robert E.; Shelton, David J.

    2015-06-01

    Patterned highly absorbing gold black film has been selectively deposited on the active surfaces of a vanadium-oxide-based infrared bolometer array. Patterning by metal lift-off relies on protection of the fragile gold black with an evaporated oxide, which preserves gold black's near unity absorption. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. Infrared responsivity is substantially improved by the gold black coating without significantly increasing noise. The increase in the time constant caused by the additional mass of gold black is a modest 14%.

  8. Entanglement from thermal black body radiation

    OpenAIRE

    Braun, Daniel

    2005-01-01

    Two non--interacting quantum systems which couple to a common environment with many degrees of freedom initially in thermal equilibrium can become entangled due to the indirect interaction mediated through this heat bath. I examine here the dynamics of reservoir induced entanglement for a heat bath consisting of a thermal electro--magnetic radiation field, such as black body radiation or the cosmic microwave background, and show how the effect can be understood as result of an effective induc...

  9. Black-body radiation in Tsallis statistics

    International Nuclear Information System (INIS)

    Some results for the black-body radiation obtained in the context of the q-thermostatistics are analyzed on both thermodynamical and statistical-mechanical levels. Since the thermodynamic potentials can be expressed in terms of Wright's special function a useful asymptotic expansion can be obtained. This expansion allows to consider thermodynamic properties away from the Boltzmann-Gibbs limit q = 1. The role of non-extensivity, q 4 behavior is considered. The application of some approximation schemes widely used in the literature to analyze the cosmic radiation is discussed. (author)

  10. Bendable, ultra-black absorber based on a graphite nanocone nanowire composite structure.

    Science.gov (United States)

    Sun, Yaoran; Evans, Julian; Ding, Fei; Liu, Nan; Liu, Wen; Zhang, Yuan; He, Sailing

    2015-07-27

    A bendable ultra-black material consisting of graphite nanocones and nanowires is fabricated through a simple plasma etching process. The optical properties of the absorber are characterized in the wavelength range of 400-2000 nm with average specular reflectance 0.05 ± 0.03% at normal incidence and the material thickness is only around 5 μm. The reflectance of the absorber remains low at large incident angles and is relatively independent of polarization. Simulations confirm the cooperative effect of the nanowires and nanocones leading to an ultra-black thin carbon material. PMID:26367669

  11. The End of the Black Hole Dark Ages, and Warm Absorbers

    CERN Document Server

    King, A R

    2013-01-01

    We consider how the radiation pressure of an accreting supermassive hole (SMBH) affects the interstellar medium around it. Much of the gas originally surrounding the hole is swept into a shell with a characteristic radius somewhat larger than the black hole's radius of influence ($\\sim$ 1-100 pc). The shell has a mass directly comparable to the ($M - \\sigma$) mass the hole will eventually reach, and may have a complex topology. We suggest that outflows from the central supermassive black holes are halted by collisions with the shell, and that this is the origin of the warm absorber components frequently seen in AGN spectra. The shell may absorb and reradiate some of the black hole accretion luminosity at long wavelengths, implying both that the bolometric luminosities of some known AGN may have been underestimated, and that some accreting SMBH may have escaped detection entirely.

  12. A semiclassical approach to the matte black-body

    Science.gov (United States)

    Ramírez-Moreno, M. A.; González-Hernández, S.; Ares de Parga, G.

    2015-11-01

    In this paper, a semiclassical approach is used to describe a kind of black-body which we will call a matte black-body. Although the frequency energy density of a black-body is deduced using a semiclassical method which includes the electromagnetic reaction force and the quantization of the energy, a phenomenological damping force, as in the explanation of the anomalous dispersion of some fluids, is considered in order to obtain the corresponding frequency energy density of the matte black-body. The concept of emissivity is incorporated into the new body in order to explain the experimental data of the radiation measured in the Earth’s atmosphere. The purpose of this article consists of showing students the applicability of semiclassical approaches in obtaining physical results.

  13. Reexamining Black-Body Shifts for Hydrogenlike Ions

    OpenAIRE

    Jentschura, U. D.; Haas, M.

    2008-01-01

    We investigate black-body induced energy shifts for low-lying levels of atomic systems, with a special emphasis on transitions used in current and planned high-precision experiments on atomic hydrogen and ionized helium. Fine-structure and Lamb-shift induced black-body shifts are found to increase with the square of the nuclear charge number, whereas black-body shifts due to virtual transitions decrease with increasing nuclear charge as the fourth power of the nuclear charge. We also investig...

  14. Patterning and hardening of gold black infrared absorber by shadow mask deposition with ethyl cyanoacrylate

    Science.gov (United States)

    Panjwani, Deep; Nader-Esfahani, Nima; Maukonen, Doug; Rezadad, Imen; Boroumand, Javaneh; Smith, Evan; Nath, Janardan; Peale, R. E.

    2013-06-01

    Patterning of gold-black infrared absorbing films by stencil lithography and hardening by polymer infusion is reported. Gold black nano-structured films are deposited through a thin metal shadow mask in a thermal evaporator in ~400 mTorr pressure of inert gas, followed by ethyl cyanoacrylate fuming through the same mask to produce rugged IR absorptive patterns of ~100 micron scale dimensions. Infrared absorptivity is determined by transmission and reflectivity measurements using a Fourier spectrometer and infrared microscope. Results indicate that the optimized hardening process reduces the usual degradation of the absorptivity with age. This work has potential application to infrared array bolometers.

  15. Effects of body and organ size on absorbed dose: there is no standard patient

    International Nuclear Information System (INIS)

    The problem of estimating the absorbed dose to organs and tissues of the human body due to the presence of a radiopharmaceutical in one or more organs is discussed. Complications are introduced by the fact that the body is not homogeneous and in many cases the organ shapes are not regular. Publications of the MIRD Committee have provided a direct means of estimating the absorbed dose (or absorbed fraction) for a number of radioisotopes. These estimates are based on Monte Carlo calculations for monoenergetic photons distributed uniformly in organs of an adult phantom. The medical physicist finds that his patient does not resemble the adult phantom. In addition, the absorbed fractions for the adult are not reasonable values for the child. This paper examines how these absorbed fraction estimates apply to a nonstandard patient

  16. Temperature fields in large radiation-absorbing bodies

    International Nuclear Information System (INIS)

    Bodies in the vicinity of radiation sources are heated by absorption of radiation energy. Information on the temperature fields in such bodies is often important from the safety point of view, e.g., in connection with possible local melting or with temperature-induced changes in the properties of materials. This paper shows how such temperature fields can be calculated. The theoretical results are supported by experimental findings. For this purpose a large body was equipped with an array of thermocouples and was irradiated in a reactor at Juelich. The paper presents an unidimensional temperature field equation, sufficient for many cases arising in practice, in a form taking into account the decrease in the heat source term in the direction of the radiation, as well as a system of equations for determining three-dimensional temperature fields with any specified boundary conditions. The system is written in a matrix from appropriate for solution by the finite element method. The matrices for a rith-prism finite element, required for practical calculations, are presented explicitly. These matrices make it possible to calculate temperature fields in very extensive bodies. (orig.)

  17. Fermi golden rule for $N$-body systems in a black-body radiation

    CERN Document Server

    Ostilli, Massimo

    2016-01-01

    We review the calculation of the Fermi golden rule for a system of $N$-body dipoles, magnetic or electric, weakly interacting with a black-body radiation. By using the magnetic or electric field-field correlation function evaluated in the 1960s for the black body radiation, we deduce a general formula for the transition rates and study its limiting, fully coherent or fully incoherent, regimes.

  18. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2006-05-01

    Full Text Available Although the definition and measurement methods of atmospheric ''black carbon'' (''BC'' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black (''brown carbon, Cbrown'' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes directly from aerosol absorption measurements near specific combustion sources, from observations of spectral properties of water extracts of continental aerosol, from laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that these species may severely bias measurements of ''BC'' and ''EC'' over vast parts of the troposphere, where mass concentration of Cbrown is high relative to that of combustion soot. We also imply that due to the strongly skewed absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. The possible consequences of these effects on our understanding of tropospheric processes are discussed.

  19. Black Cr/α-Cr2O3 nanoparticles based solar absorbers

    International Nuclear Information System (INIS)

    Monodisperse spherical core–shell particles of Cr/α-Cr2O3 with high adhesion were successfully coated on rough copper substrates by a simple self-assembly-like method for the use in solar thermal absorbers. The structure and morphology of the core-shell particles of Cr/α-Cr2O3 were effectively controlled by deposition temperature and the pH of the initial precursor solution. Their characterizations were carried out with X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and attenuated total reflection, as well as UV–vis diffuse reflectance spectroscopy. The samples aged for more than 40 h at 75 °C exhibit the targeted high absorbing optical characteristic “Black chrome” while those aged for ≤40 h show a significant high UV–vis diffuse reflectance “green color”.

  20. Use of nuclear techniques in the characterization of chrome black solar absorber surfaces

    International Nuclear Information System (INIS)

    A set of electrodeposited chrome black solar absorbers has been subjected to ion beam analysis in an attempt to determine the concentration depth profiles of the major elemental constituents. Chromium distributions were obtained using the 52Cr(p,γ)53Mn nuclear reaction, which is resonant at E = 1005.2 keV. The possibility was investigated of inferring oxygen distributions from the γ-ray lineshapes (measured with a Ge(Li) detector) of the direct capture reaction 16O(p,γ)17F. Concentration profiles were also obtained for fluorine and sodium contaminants in some chrome blacks. Complete experimental details are given of the various nuclear techniques used. The results of these measurements are discussed in terms of the microscopic physical features of the selective surfaces and are related to the known photothermal properties of the surfaces

  1. Attractive optical forces from black-body radiation

    CERN Document Server

    Sonnleitner, Matthias; Ritsch, Helmut

    2013-01-01

    Black-body radiation around hot objects induces AC Stark shifts of the energy levels of nearby atoms and molecules. These shifts are roughly proportional to the fourth power of the temperature and induce a force decaying with the third power of the distance from the object's surface. We explicitly calculate the resulting attractive black-body optical dipole force for ground state hydrogen atoms. Surprisingly this force can surpass the repulsive radiation pressure and actually pull the atoms towards the surface with a force stronger than gravity. We exemplify the dominance of the "black-body force" over gravity for hydrogen in a cloud of hot dust particles. These forces, which have been neglected to date, appear highly relevant in various astrophysical scenarios, in particular since analogous results hold for a wide class of broadband radiation sources.

  2. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2006-01-01

    Full Text Available Although the definition and measurement techniques for atmospheric 'black carbon' ('BC' or 'elemental carbon'' ('EC' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ('brown carbon, Cbrown' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1 spectral aerosol light absorption measurements near specific combustion sources, (2 observations of spectral properties of water extracts of continental aerosol, (3 laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4 indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of 'BC' and 'EC' over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine 'EC' are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of 'BC' suffer from a number of problems: (1 many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2 there is no unique conversion factor between light absorption and 'EC' or 'BC' concentration in ambient aerosols, and (3 the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our

  3. Tidal interaction of black holes and Newtonian viscous bodies

    CERN Document Server

    Poisson, Eric

    2009-01-01

    The tidal interaction of a (rotating or nonrotating) black hole with nearby bodies produces changes in its mass, angular momentum, and surface area. Similarly, tidal forces acting on a Newtonian, viscous body do work on the body, change its angular momentum, and part of the transferred gravitational energy is dissipated into heat. The equations that describe the rate of change of the black-hole mass, angular momentum, and surface area as a result of the tidal interaction are compared with the equations that describe how the tidal forces do work, torque, and produce heat in the Newtonian body. The equations are strikingly similar, and unexpectedly, the correspondence between the Newtonian-body and black-hole results is revealed to hold in near-quantitative detail. The correspondence involves the combination k_2 \\tau of ``Love quantities'' that incorporate the details of the body's internal structure; k_2 is the tidal Love number, and \\tau is the viscosity-produced delay between the action of the tidal forces a...

  4. Dual band sensitivity enhancements of a VO(x) microbolometer array using a patterned gold black absorber.

    Science.gov (United States)

    Smith, Evan M; Panjwani, Deep; Ginn, James; Warren, Andrew P; Long, Christopher; Figuieredo, Pedro; Smith, Christian; Nath, Janardan; Perlstein, Joshua; Walter, Nick; Hirschmugl, Carol; Peale, Robert E; Shelton, David

    2016-03-10

    Infrared-absorbing gold black has been selectively patterned onto the active surfaces of a vanadium-oxide-based infrared bolometer array. Patterning by metal lift-off relies on protection of the fragile gold black with an evaporated oxide, which preserves much of gold black's high absorptance. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. For our fabricated devices, infrared responsivity is improved 22% in the long-wave IR and 70% in the mid-wave IR by the gold black coating, with no significant change in detector noise, using a 300°C blackbody and 80 Hz chopping rate. The increase in the time constant caused by the additional mass of gold black is ∼15%. PMID:26974804

  5. 1 Mixing state and absorbing properties of black carbon during Arctic haze

    Science.gov (United States)

    Zanatta, Marco; Gysel, Martin; Eleftheriadis, Kosas; Laj, Paolo; Hans-Werner, Jacobi

    2016-04-01

    The Arctic atmosphere is periodically affected by the Arctic haze occurring in spring. One of its particulate components is the black carbon (BC), which is considered to be an important contributor to climate change in the Arctic region. Beside BC-cloud interaction and albedo reduction of snow, BC may influence Arctic climate interacting directly with the solar radiation, warming the corresponding aerosol layer (Flanner, 2013). Such warming depends on BC atmospheric burden and also on the efficiency of BC to absorb light, in fact the light absorption is enhanced by mixing of BC with other atmospheric non-absorbing materials (lensing effect) (Bond et al., 2013). The BC reaching the Arctic is evilly processed, due to long range transport. Aging promote internal mixing and thus absorption enhancement. Such modification of mixing and is quantification after long range transport have been observed in the Atlantic ocean (China et al., 2015) but never investigated in the Arctic. During field experiments conducted at the Zeppelin research site in Svalbard during the 2012 Arctic spring, we investigated the relative precision of different BC measuring techniques; a single particle soot photometer was then used to assess the coating of Arctic black carbon. This allowed quantifying the absorption enhancement induced by internal mixing via optical modelling; the optical assessment of aged black carbon in the arctic will be of major interest for future radiative forcing assessment.Optical characterization of the total aerosol indicated that in 2012 no extreme smoke events took place and that the aerosol population was dominated by fine and non-absorbing particles. Low mean concentration of rBC was found (30 ng m-3), with a mean mass equivalent diameter above 200 nm. rBC concentration detected with the continuous soot monitoring system and the single particle soot photometer was agreeing within 15%. Combining absorption coefficient observed with an aethalometer and rBC mass

  6. The Black Body and Representations of the (In)human

    OpenAIRE

    Hsiao, Li-Chun

    2007-01-01

    Li-Chun Hsiao, in his article "The Black Body and Representations of the (In)human," takes cues from the theoretical insights of Agamben's "bare life" as well as Laclau's and Mouffe's "social antagonism" and explores how the slave can be considered a constitutive element which is nevertheless foreclosed from Western democracies. Hsiao also analyzes the various ways the term "slave" functions as trope in the founding discourses of Western democracy. "Bare life" remains included in politics "in...

  7. Estimation of absorbed organ doses and effective dose based on body mass index in digital radiography

    International Nuclear Information System (INIS)

    With the introduction of digital radiography, patients undergoing radiographic procedures are subject to being overexposed to radiation. Therefore, it is necessary to estimate the absorbed organ dose and the effective dose, which are significant for patient health, along with body type. During chest radiographic examinations conducted in 899 patients for screening, the absorbed dose of the 13 major organs, the average whole-body dose, and two effective doses weighted by factors published in ICRP 60 and ICRP 103 were calculated on the basis of patient information such as height, weight and examination condition, including kilovolt potential, focus-skin distance and entrance surface dose (ESD), using a PC-based Monte Carlo program simulation. It was found that dose per unit ESD had a tendency to decrease with body mass index (BMI). In particular, the absorbed dose for most organs was larger at high voltages (140 kVp) than at low voltages (120 kVp, 100 kVp). In addition, the effective dose which was based on ICRP 60 and ICRP 103 also represented the same tendency in respect of BMI and tube voltage. (authors)

  8. Emitter near an arbitrary body: Purcell effect, optical theorem and the Wheeler-Feynman absorber

    CERN Document Server

    Venkatapathi, Murugesan

    2012-01-01

    The altered spontaneous emission of an emitter near an arbitrary body can be elucidated using an energy balance of the electromagnetic field. From a classical point of view it is trivial to show that the field scattered back from any body should alter the emission of the source. But it is not at all apparent that the total radiative and non-radiative decay in an arbitrary body can add to the vacuum decay rate of the emitter (i.e.) an increase of emission that is just as much as the body absorbs and radiates in all directions. This gives us an opportunity to revisit two other elegant classical ideas of the past, the optical theorem and the Wheeler-Feynman absorber theory of radiation. It also provides us alternative perspectives of Purcell effect and generalizes many of its manifestations, both enhancement and inhibition of emission. When the optical density of states of a body or a material is difficult to resolve (in a complex geometry or a highly inhomogeneous volume) such a generalization offers new direct...

  9. Multilayer black phosphorus as broadband saturable absorber for pulsed lasers from 1 to 2.7 {\\mu}m wavelength

    CERN Document Server

    Kong, Lingchen; Xie, Guoqiang; Guo, Zhinan; Zhang, Han; Yuan, Peng; Qian, Liejia

    2015-01-01

    It attracts wide interest to seek universe saturable absorber covering wavelengths from near infrared to mid-infrared band. Multilayer black phosphorus, with variable direct bandgap (0.3-2 eV) depending on the layer number, becomes a good alternative as a universe saturable absorber for pulsed lasers. In this contribution, we first experimentally demonstrated broadband saturable absorption of multilayer black phosphorus from 1 {\\mu}m to 2.7 {\\mu}m wavelength. With the as-fabricated black phosphorus nanoflakes as saturable absorber, stable Q-switching operation of bulk lasers at 1.03 {\\mu}m, 1.93 {\\mu}m, 2.72 {\\mu}m were realized, respectively. In contrast with large-bandgap semiconducting transition metal dichalcogenides, such as MoS2, MoSe2, multilayer black phosphorus shows particular advantage at the long wavelength regime thanks to its narrow direct bandgap. This work will open promising optoelectronic applications of black phosphorus in mid-infrared spectral region and further demonstrate that BP may fil...

  10. Metal hydride flux trap neutron absorber arrangement for a nuclear fuel storage body

    International Nuclear Information System (INIS)

    In a nuclear fuel storage body including a pool of fast neutron slowing fluid and a plurality of upright storage cans submerged in said fluid and disposed in a spaced side-by-side array, each storage can being composed of a plurality of side walls connected together to receive and store a nuclear fuel assembly, a plurality of flux trap neutron absorber arrangements disposed in said storage body between said storage cans, each of said flux trap neutron absorber arrangements is described comprising: (a) separate means extending vertically along and attached to the exterior of each of adjacent side walls of adjacent pairs of said spaced storage cans for forming respective pockets extending along said adjacent side walls and being spaced from one another, said pocket forming means being an outer elongated covering extending vertically along and attached along its periphery to each of said adjacent side walls; (b) an elongated flat plate of a thermal neutron absorber material mounted in each of said pockets, said plates of thermal neutron absorber material being likewise spaced from one another and defining a fast neutron slow-down region there between; (c) a slab of a metal hydride disposed in said fast neutron slow-down region between said plates of thermal neutron absorber material and said separate pocket forming means on said adjacent side walls; and (d) a canister containing said slab of said metal hydride being disposed in said fast neutron slow-down region, said canister being connected to one of said adjacent side walls of said adjacent storage cans; (e) said canister including a hollow metal container having a rectangular cross-section defined by a pair of spaced side walls and a pair of lateral end walls extending between and rigidly interconnecting said side walls, said canister being filled by said slab of metal hydride which is disposed in contact with said side and lateral end walls of said canister

  11. Parametric study of two-body floating-point wave absorber

    Science.gov (United States)

    Amiri, Atena; Panahi, Roozbeh; Radfar, Soheil

    2016-03-01

    In this paper, we present a comprehensive numerical simulation of a point wave absorber in deep water. Analyses are performed in both the frequency and time domains. The converter is a two-body floating-point absorber (FPA) with one degree of freedom in the heave direction. Its two parts are connected by a linear mass-spring-damper system. The commercial ANSYS-AQWA software used in this study performs well in considering validations. The velocity potential is obtained by assuming incompressible and irrotational flow. As such, we investigated the effects of wave characteristics on energy conversion and device efficiency, including wave height and wave period, as well as the device diameter, draft, geometry, and damping coefficient. To validate the model, we compared our numerical results with those from similar experiments. Our study results can clearly help to maximize the converter's efficiency when considering specific conditions.

  12. Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser

    CERN Document Server

    Luo, Zhi-Chao; Guo, Zhi-Nan; Jiang, Xiao-Fang; Luo, Ai-Ping; Zhao, Chu-Jun; Yu, Xue-Feng; Xu, Wen-Cheng; Zhang, Han

    2015-01-01

    Few-layer black phosphorus (BP), as the most alluring graphene analogue owing to its similar structure as graphene and thickness dependent direct band-gap, has now triggered a new wave of research on two-dimensional (2D) materials based photonics and optoelectronics. However, a major obstacle of practical applications for few-layer BPs comes from their instabilities of laser-induced optical damage. Herein, we demonstrate that, few-layer BPs, fabricated through the liquid exfoliation approach, can be developed as a new and practical saturable absorber (SA) by depositing few-layer BPs with microfiber. The saturable absorption property of few-layer BPs had been verified through an open-aperture z-scan measurement at the telecommunication band and the microfiber-based BP device had been found to show a saturable average power of ~4.5 mW and a modulation depth of 10.9%, which is further confirmed through a balanced twin detection measurement. By further integrating this optical SA device into an erbium-doped fiber...

  13. Black phosphorus as a new broadband saturable absorber for infrared passively Q-switched fiber lasers

    CERN Document Server

    Jiang, Tian; Zheng, Xin; Yu, Hao; Cheng, Xiang-Ai

    2015-01-01

    Black phosphorus (BP) with its enticing electric and optical properties is intensely researched in the field of optoelectronics. In this paper, Q-switched pulses at 1550 nm and 2 um wavelengths are obtained by inserting bulk-structured BP based saturable absorber (SA) into an erbium-doped fiber laser (EDFL) and an thulium/holmium-doped fiber laser (THDFL), respectively. The BP-SA was prepared by depositing powered BP material on to the flat side of a side-polished single mode fiber. Q-switched 1550 nm pulses with width tuned from 9.35 to 31 us were obtained for the EDFL. For the THDFL, over 100 nm wavelength range could be achieved from 1832 to 1935 nm by adjusting the pump power. To the best of our knowledge, these results demonstrated the broadband saturable absorption property of BP and for the first time verified that BP as a new two-dimensional material for applications in saturable absorption devices.

  14. Thermalization of magnetized electrons from black body radiation

    International Nuclear Information System (INIS)

    We describe an interesting mechanism whereby an electron in a strong magnetic field can have both the parallel and perpendicular motions come into thermal equilibrium with black body radiation. The mechanism does not include any collisions with other particles and can overcome the extreme slowing of thermalization of highly magnetized particles at low temperatures. The mechanism depends upon the magnetic field strength having a spatial variation. We provide results from two example cases. This mechanism could affect the temperatures that can be achieved in experiments devoted to trapping antihydrogen

  15. Measured Wavelength-Dependent Absorption Enhancement of Internally Mixed Black Carbon with Absorbing and Nonabsorbing Materials.

    Science.gov (United States)

    You, Rian; Radney, James G; Zachariah, Michael R; Zangmeister, Christopher D

    2016-08-01

    Optical absorption spectra of laboratory generated aerosols consisting of black carbon (BC) internally mixed with nonabsorbing materials (ammonium sulfate, AS, and sodium chloride, NaCl) and BC with a weakly absorbing brown carbon surrogate derived from humic acid (HA) were measured across the visible to near-IR (550 to 840 nm). Spectra were measured in situ using a photoacoustic spectrometer and step-scanning a supercontinuum laser source with a tunable wavelength and bandwidth filter. BC had a mass-specific absorption cross section (MAC) of 7.89 ± 0.25 m(2) g(-1) at λ = 550 nm and an absorption Ångström exponent (AAE) of 1.03 ± 0.09 (2σ). For internally mixed BC, the ratio of BC mass to the total mass of the mixture was chosen as 0.13 to mimic particles observed in the terrestrial atmosphere. The manner in which BC mixed with each material was determined from transmission electron microscopy (TEM). AS/BC and HA/BC particles were fully internally mixed, and the BC was both internally and externally mixed for NaCl/BC particles. The AS/BC, NaCl/BC, and HA/BC particles had AAEs of 1.43 ± 0.05, 1.34 ± 0.06, and 1.91 ± 0.05, respectively. The observed absorption enhancement of mixed BC relative to the pure BC was wavelength dependent for AS/BC and decreased from 1.5 at λ = 550 nm with increasing wavelength while the NaCl/BC enhancement was essentially wavelength independent. For HA/BC, the enhancement ranged from 2 to 3 and was strongly wavelength dependent. Removal of the HA absorption contribution to enhancement revealed that the enhancement was ≈1.5 and independent of wavelength. PMID:27359341

  16. Modal element method for scattering and absorbing of sound by two-dimensional bodies

    Science.gov (United States)

    Baumeister, K. J.; Kreider, K. L.

    1993-01-01

    The modal element method for acoustic scattering from a 2-D body is presented. The body may be acoustically soft (absorbing) or hard (reflecting). The infinite computational region is divided into two subdomains - the bounded finite element domain, which is characterized by complicated geometry and/or variable material properties, and the surrounding unbounded homogeneous domain. The acoustic pressure field is represented approximately in the finite element domain by a finite element solution, and is represented analytically by an eigenfunction expansion in the homogeneous domain. The two solutions are coupled by the continuity of pressure and velocity across the interface between the two subdomains. Also, for hard bodies, a compact modal ring grid system is introduced for which computing requirements are drastically reduced. Analysis for 2-D scattering from solid and coated (acoustically treated) bodies is presented, and several simple numerical examples are discussed. In addition, criteria are presented for determining the number of modes to accurately resolve the scattered pressure field from a solid cylinder as a function of the frequency of the incoming wave and the radius of the cylinder.

  17. Thermal damage suppression of a black phosphorus saturable absorber for high-power operation of pulsed fiber lasers

    Science.gov (United States)

    Lee, Donghyun; Park, Kichul; Debnath, Pulak C.; Kim, Inho; Song, Yong-Won

    2016-09-01

    Recent studies of black phosphorus (BP) have shown its future potential in the field of photonics. We determined the optical damage threshold of BP at 21.8 dBm in a fiber ring laser cavity, and demonstrated the high-power operation capacity of an evanescent field interaction-based BP saturable absorber. The long-term stability of a passively mode-locked fiber laser with a saturable absorber operating at the optical power of 23.3 dBm was verified for 168 h without any significant performance degradation. The center wavelength, spectral width, and pulse width of the laser output are 1558.8 nm, 14.2 nm, and 805 fs, respectively.

  18. Numerical models of black body dominated GRBs: II. Emission properties

    CERN Document Server

    Cuesta-Martínez, Carlos F; Mimica, Petar; Thöne, Christina C; de Ugarte-Postigo, Antonio

    2014-01-01

    We extend an existing theoretical model to explain the class of Black-Body Dominated (BBD) gamma-ray bursts (GRBs), long lasting events characterized by the presence of a significant thermal component trailing the GRB prompt emission, and also by an absence of a traditional afterglow. GRB 101225A, the Christmas Burst, is a prototype of such class. It has been suggested that BBD-GRBs could be observed after a merger in a binary system consisting of a neutron star and a Helium core of a main sequence star. Using detailed relativistic hydrodynamic numerical simulations we model the propagation of ultrarelativistic jets through the environments created by such mergers. In this paper we focus on explaining the emission properties of the jet evolution computing the whole radiative signature (both thermal and non-thermal) of the jet dynamical evolution. A comprehensive parameter study of the jet/environment interaction has been performed and synthetic spectra and light curves are compared with the observational data...

  19. Dynamical Casimir effect and the black body spectrum

    International Nuclear Information System (INIS)

    Creation of scalar massless particles in two-dimensional Minkowski space time-as predicted by the dynamical Casimir effect-is studied for the case of a semitransparent mirror initially at rest, then accelerating for some finite time, along a specified trajectory, and finally moving with constant velocity. When the reflection and transmission coefficients are those in the model proposed by Barton, Calogeracos and Nicolaevici [r(w) = -iα/(ω + iα) and s(w) = ω/(ω + iα), with α ≥ 0], the Bogoliubov coefficients on the back side of the mirror can be computed exactly. This allows us to prove that, when α is very large (case of an ideal, perfectly reflecting mirror) a thermal emission of scalar massless particles obeying Bose-Einstein statistics is radiated from the mirror (a black body radiation), in accordance with previous results in the literature. However, when α is finite (semitransparent mirror, a physically realistic situation) the striking result is obtained that the thermal emission of scalar massless particles obeys Fermi-Dirac statistics. Possible consequences of this result are envisaged. (fast track communication)

  20. Incongruence in body image and body mass index: A surrogate risk marker in Black women for type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Rynal Devanathan

    2013-01-01

    Full Text Available Background: Excess weight contributes to the development and progression of Type 2 diabetes mellitus (T2DM. Distorted body image amongst urban Black women and the perception that thinness is linked with HIV, may however be compounding the problem, particularly in areas with a high HIV burden.Objectives: This study aimed to compare the perception of body image in urban Black women with and without T2DM.Methods: A cross-sectional comparative study was conducted on 328 Black women systematically sampled into two groups (with and without T2DM. Body mass index (BMI (weight [kg]/height[m2] was determined and the adapted Stunkard Body Image Silhouettes for Black women was used to determine perceived body image (PBI.Results: Seventy-two per cent had T2DM and in this group 89% were obese, with a mean BMI of 39.5 kg/m2 (s.d. ± 8.5. In the non-diabetes group (NDG 44% were obese, with a mean BMIof 31.3 kg/m2 (s.d. ± 9.0 Black women underestimated their body image across all weight categories (p < 0.05. Both groups (99% of the study group also perceived thinness as being associated with HIV.Conclusions: This study identified an incongruence between PBI and actual BMI amongst urban Black women. This, combined with their belief that thinness is associated with HIV, places those with T2DM at risk of secondary complications arising from diabetes mellitus, and those without diabetes mellitus at a higher risk of developing T2DM. A discrepancy between PBI and BMI may therefore serve as a risk marker to alert clinicians to use a more ethno-cultural specific approach in engaging with urban Black women regarding weight loss strategies in the future.

  1. Ethnic Identity and Body Image among Black and White College Females

    Science.gov (United States)

    Baugh, Eboni; Mullis, Ron; Mullis, Ann; Hicks, Mary; Peterson, Gary

    2010-01-01

    Objective: This study examines ethnic identity and body image in black and white college females. Participants: Researchers surveyed 118 students at 2 universities, 1 traditionally white and 1 historically black. Methods: Correlations and multivariate analysis of variance (MANOVA) were used to investigate the relationship between race, ethnic…

  2. Body Dissatisfaction and Characteristics of Disordered Eating among Black and White Early Adolescent Girls and Boys

    Science.gov (United States)

    Jung, Jaehee; Forbes, Gordon B.

    2013-01-01

    Multiple measures of body dissatisfaction and behaviors associated with disordered eating were studied in 258 White girls, 223 White boys, 106 Black girls, and 82 Black boys. All participants were unpaid volunteers between the ages of 12 and 15 attending six middle schools in Delaware and Maryland. On two self-ideal figure drawing discrepancy…

  3. RELATIONSHIPS BETWEEN ULTRASONIC ESTIMATES OF CARCASS TRAITS AND BODY MEASUREMENTS OF JAPANESE BLACK BULL

    OpenAIRE

    Sri Rachma, Aprilita Bugiwati

    2008-01-01

    This experiment was done at 292 head of Japanese black bull at Kagoshima and Miyazaki Prefectural Experimental Stations Japan to find out the relationship between ultrasonic estimates of carcass traits and body measurements as one of criteria to select Japanese black bull. The carcass traits of 20 months of age were predicted using the ultrasonic machine. The body dimensions were measured at the end of performance test (12 months of age) and 16 months of age. The ultrasonic evaluati...

  4. Black phosphorus as saturable absorber for the Q-switched Er:ZBLAN fiber laser at 2.8 {\\mu}m

    CERN Document Server

    Qin, Zhipeng; Zhang, Han; Zhao, Chujun; Yuan, Peng; Wen, Shuangchun; Qian, Liejia

    2015-01-01

    Black phosphorus, a newly emerged two-dimensional material, has attracted wide attention as novel photonic material. Here, multi-layer black phosphorus is successfully fabricated by liquid phase exfoliation method. By employing black phosphorus as saturable absorber, we demonstrate a passively Q-switched Er-doped ZBLAN fiber laser at the wavelength of 2.8 {\\mu}m. The modulation depth and saturation fluence of the black phosphorus saturable absorber are measured to be 15% and 9 {\\mu}J/cm2, respectively. The Q-switched fiber laser delivers a maximum average power of 485 mW with corresponding pulse energy of 7.7 {\\mu}J and pulse width of 1.18 {\\mu}s at repetition rate of 63 kHz. To the best of our knowledge, this is the first time to demonstrate that black phosphorus can realize Q-switching of 2.8-{\\mu}m fiber laser. Our research results show that black phosphorus is a promising saturable absorber for mid-infrared pulsed lasers.

  5. Spin-multipole effects in binary black holes and the test-body limit

    CERN Document Server

    Vines, Justin

    2016-01-01

    We discuss the Hamiltonian for the conservative dynamics of generic-orbit arbitrary-mass-ratio spinning binary black holes, at the leading post-Newtonian orders at each order in an expansion in spins, to all orders in the spins. The leading-order couplings can all be obtained from a map to the motion of a test black hole (a test body with the spin-induced multipoles of a Kerr black hole) in the Kerr spacetime, as is confirmed with direct post-Newtonian calculations for arbitrary mass ratios. Furthermore, all of the couplings can be "deduced" from those of a pole-dipole test body in Kerr.

  6. Numerical Solutions of Inverse Black Body Radiation Problems with Gaussian-Laguerre Quadrature Formula

    Science.gov (United States)

    Yang, Ping; Feng, Xue-Wen; Liang, Wen-Jun; Wu, Kai-Su

    2015-02-01

    It is the main aim of this paper to investigate the numerical solutions of the inverse black body radiation problems. The inverse black body radiation problem is ill-posed. Using Gaussian-Laguerre integral formula which is a higher accuracy numerical integration formula with less node numbers to approximate the integral item of black body radiation equation, the black radiation equation is converted into a group of lower dimension algebraic equations. To solve the lower dimension algebraic equation, it only needs to use common Tikhonov regularization methods. The regularization parameter is chosen by using L-curve. Our method reduces the complexity of the algorithm, so the operability of our method is enhanced. Numerical results show that our algorithm is simple and effective, and has better calculation accuracy at the same time.

  7. Who's that Girl: Television's Role in the Body Image Development of Young White and Black Women

    Science.gov (United States)

    Schooler, Deborah; Ward, L. Monique; Merriwether, Ann; Caruthers, Allison

    2004-01-01

    Although findings indicate a connection between frequent media use and greater body dissatisfaction, little attention has focused on the role of race. Accordingly, this study investigates the relation between television viewing and body image among 87 Black and 584 White women. Participants reported monthly viewing amounts of mainstream and…

  8. Vibration Suppression of a Helicopter Fuselage by Pendulum Absorbers : Rigid-Body Blades with Aerodynamic Excitation Force

    Science.gov (United States)

    Nagasaka, Imao; Ishida, Yukio; Koyama, Takayuki; Fujimatsu, Naoki

    Currently, some kinds of helicopters use pendulum absorbers in order to reduce vibrations. Present pendulum absorbers are designed based on the antiresonance concept used in the linear theory. However, since the vibration amplitudes of the pendulum are not small, it is considered that the nonlinearity has influence on the vibration characteristics. Therefore, the best suppression cannot be attained by using the linear theory. In a helicopter, periodic forces act on the blades due to the influences of the air thrust. These periodic forces act on the blades with the frequency which is the integer multiple of the rotational speed of the rotor. Our previous study proposed a 2-degree-of-freedom (2DOF) model composed of a rotor blade and a pendulum absorber. The blade was considered as a rigid body and it was excited by giving a sinusoidal deflection at its end. The present paper proposes a 3DOF model that is more similar to the real helicopter, since the freedom of the fuselage is added and the periodic forces are applied to the blade by aerodynamic force. The vibration is analyzed considering the nonlinear characteristics. The resonance curves of rotor blades with pendulum absorbers are obtained analytically and experimentally. It is clarified that the most efficient condition is obtained when the natural frequency of the pendulum is a little bit different from the frequency of the external force. Various unique nonlinear characteristics, such as bifurcations, are also shown.

  9. Polarization and Thickness Dependent Absorption Properties of Black Phosphorus: New Saturable Absorber for Ultrafast Pulse Generation

    Science.gov (United States)

    Li, Diao; Jussila, Henri; Karvonen, Lasse; Ye, Guojun; Lipsanen, Harri; Chen, Xianhui; Sun, Zhipei

    2015-10-01

    Black phosphorus (BP) has recently been rediscovered as a new and interesting two-dimensional material due to its unique electronic and optical properties. Here, we study the linear and nonlinear optical properties of BP flakes. We observe that both the linear and nonlinear optical properties are anisotropic and can be tuned by the film thickness in BP, completely different from other typical two-dimensional layered materials (e.g., graphene and the most studied transition metal dichalcogenides). We then use the nonlinear optical properties of BP for ultrafast (pulse duration down to ~786 fs in mode-locking) and large-energy (pulse energy up to >18 nJ in Q-switching) pulse generation in fiber lasers at the near-infrared telecommunication band ~1.5 μm. We observe that the output of our BP based pulsed lasers is linearly polarized (with a degree-of-polarization ~98% in mode-locking, >99% in Q-switching, respectively) due to the anisotropic optical property of BP. Our results underscore the relatively large optical nonlinearity of BP with unique polarization and thickness dependence, and its potential for polarized optical pulse generation, paving the way to BP based nonlinear and ultrafast photonic applications (e.g., ultrafast all-optical polarization switches/modulators, frequency converters etc.).

  10. Extended charge accumulation in ruthenium-4H-imidazole-based black absorbers: a theoretical design concept.

    Science.gov (United States)

    Kupfer, Stephan

    2016-05-11

    A theoretical-guided design concept aiming to achieve highly efficient unidirectional charge transfer and multi-charge separation upon successive photoexcitation for light-harvesting dyes in the scope of supramolecular photocatalysts is presented. Four 4H-imidazole-ruthenium(ii) complexes incorporating a biimidazole-based electron-donating ligand sphere have been designed based on the well-known 4H-imidazole-ruthenium(ii) polypyridyl dyes. The quantum chemical evaluation, performed at the density functional and time-dependent density functional level of theory, revealed extraordinary unidirectional charge transfer bands from the near-infrared to the ultraviolet region of the absorption spectrum upon multi-photoexcitation. Spectro-electrochemical simulations modeling photoexcited intermediates determined the outstanding multi-electron storage capacity for this novel class of black dyes. These remarkable photochemical and photophysical properties are found to be preserved upon site-specific protonation rendering 4H-imidazole-ruthenium(ii) biimidazole dyes ideal for light-harvesting applications in the field of solar energy conversion. PMID:27121270

  11. Black phosphorus saturable absorber for ultrafast mode-locked pulse laser via evanescent field interaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kichul; Lee, Young Tack; Choi, Won-Kook; Song, Yong-Won [Center for Opto-electronic Materials and Devices, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Lee, Junsu; Lee, Ju Han [School of Electrical and Computer Engineering, University of Seoul (Korea, Republic of)

    2015-12-15

    Black phosphorus, or BP, has found a lot of applications in recent years including photonics. The most recent studies have shown that the material has an excellent optical nonlinearity useful in many areas, one of which is in saturable absorption for passive mode-locking. A direct interaction scheme for mode-locking, however, has a potential to optically cause permanent damage to the already delicate material. Evanescent field interaction scheme has already been proven to be a useful method to prevent such danger for other 2-dimensional nanomaterials. In this report, we have utilized the evanescent field interaction to demonstrate that the optical nonlinear characteristics of BP is sufficiently strong to use in such an indirect interaction method. The successful demonstration of the passive mode-locking operation has generated pulses with the pulse duration, repetition rate, and time bandwidth product of 2.18 ps, 15.59 MHz, and 0.336, respectively. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Black phosphorus saturable absorber for ultrafast mode-locked pulse laser via evanescent field interaction

    International Nuclear Information System (INIS)

    Black phosphorus, or BP, has found a lot of applications in recent years including photonics. The most recent studies have shown that the material has an excellent optical nonlinearity useful in many areas, one of which is in saturable absorption for passive mode-locking. A direct interaction scheme for mode-locking, however, has a potential to optically cause permanent damage to the already delicate material. Evanescent field interaction scheme has already been proven to be a useful method to prevent such danger for other 2-dimensional nanomaterials. In this report, we have utilized the evanescent field interaction to demonstrate that the optical nonlinear characteristics of BP is sufficiently strong to use in such an indirect interaction method. The successful demonstration of the passive mode-locking operation has generated pulses with the pulse duration, repetition rate, and time bandwidth product of 2.18 ps, 15.59 MHz, and 0.336, respectively. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Spin-multipole effects in binary black holes and the test-body limit

    OpenAIRE

    Vines, Justin; Steinhoff, Jan

    2016-01-01

    We discuss the Hamiltonian for the conservative dynamics of generic-orbit arbitrary-mass-ratio spinning binary black holes, at the leading post-Newtonian orders at each order in an expansion in spins, to all orders in the spins. The leading-order couplings can all be obtained from a map to the motion of a test black hole (a test body with the spin-induced multipoles of a Kerr black hole) in the Kerr spacetime, as is confirmed with direct post-Newtonian calculations for arbitrary mass ratios. ...

  14. Using a black phosphorus saturable absorber to generate dual wavelengths in a Q-switched ytterbium-doped fiber laser

    Science.gov (United States)

    Rashid, F. A. A.; Azzuhri, Saaidal R.; Salim, M. A. M.; Shaharuddin, R. A.; Ismail, M. A.; Ismail, M. F.; Razak, M. Z. A.; Ahmad, H.

    2016-08-01

    Using a few-layer black phosphorus (BP) thin film that acts as a saturable absorber (SA) in an ytterbium-doped fiber laser setup, we experimentally demonstrated a passively dual-wavelength Q-switching laser operation. The setup also incorporated a D-shaped polished fiber as a wavelength selective filter. As the SA was used in the ring cavity, a dual-wavelength Q-switch produced consistent outputs at 1038.68 and 1042.05 nm. A maximum pulse energy of 2.09 nJ with a shortest pulse width of 1.16 µs was measured for the achieved pulses. In addition, the repetition rate increased from 52.52 to 58.73 kHz with the increment of the pump level. Throughout the measurement process, the results were obtained consistently and this demonstrates that the BP film is a very good candidate to produce Q-switching pulses for the 1 micron region.

  15. Thulium/holmium-doped fiber laser passively mode locked by black phosphorus nanoplatelets-based saturable absorber.

    Science.gov (United States)

    Yu, Hao; Zheng, Xin; Yin, Ke; Cheng, Xiang'ai; Jiang, Tian

    2015-12-01

    By coupling black phosphorus (BP) nanoplatelets (NPs) with a fiber-taper evanescent light field, a saturable absorber (SA) based on the BP NPs has been successfully fabricated and used in a thulium/holmium-doped fiber laser as the mode locker. The SA had a modulation depth of ∼9.8% measured at 1.93 μm. A stable mode-locking operation at 1898 nm was achieved with a pulse width of 1.58 ps and a fundamental mode-lock repetition rate of 19.2 MHz. By increasing the pump intensity, phenomena of multi-pulsing operations, including harmonic mode-locked states and soliton bunches, were obtained in the experiment, showing that the BP NPs possess an ultrafast optical response time. This work suggests that the BP NPs-based SA is potentially useful for ultrashort, pulsed laser operations in the eye-safe region of 2 μm. PMID:26836690

  16. Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

    Directory of Open Access Journals (Sweden)

    Sukanta Das

    2014-01-01

    Full Text Available In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2 mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of −32 dB at 10.64 GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be −29.56 dB at 11.7 GHz. A consistence reflection loss value (>−24 dB was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth.

  17. On the thermodynamics of the conversion of partially polarized black-body radiation

    OpenAIRE

    Badescu, V.

    1992-01-01

    This paper considers a model consisting of : (i) a source of partially polarized black-body radiation (the pump), (ii) a thermally radiative or non-radiative ambient sink and (iii) two energy converters. The first converter (RH) transforms the energy of the black-body radiation into heat, while the second one (HW) (which has a non-zero entropy generation rate) uses that heat to produce work. The entropy-generation rates in the two converters are non-negative only when some conditions are sati...

  18. Black Pete, "smug ignorance," and the value of the black body in postcolonial Netherlands

    NARCIS (Netherlands)

    Van Der Pijl, Yvon; Goulordava, Karina

    2014-01-01

    This article discusses the controversies over the blackface figure Black Pete (Zwarte Piet)-central to the popular Dutch Saint Nicholas holiday tradition-and the public uproar surrounding the Saint Nicholas feast in 2013. It combines history, social theory, and patchwork ethnography, and draws on th

  19. Absorbed body dose simulation in Thyroid cancer therapy using MCNP4Cand ITScodes and comparison to experimental results

    International Nuclear Information System (INIS)

    Two standard particle transport codes of MCNP4C and integrated tiger series were used to estimate the total body dose in a thyroid cancer therapy study, with I-131 as the radionuclide source. Human body was modeled by water and soft tissue ellipsoids. Phantoms' dimensions were selected according to Brow nell recommendation. Absorbed fractions were calculated by both codes for different phantoms and for gammas with 0.364 MeV energy, which has the highest fraction in I-131 emitting gammas. Results were compared to the data published by Brow nell et.al.. Figure 1 shows the results of MCNP4C and Integrated Tiger Series with results published by Brow nell et. al.

  20. Black Sun: Ocular Invisibility of Relativistic Luminous Astrophysical Bodies

    CERN Document Server

    Lee, Jeffrey S

    2015-01-01

    The relativistic Doppler shifting of visible electromagnetic radiation to beyond the human ocular range reduces the incident radiance of the source. Consequently, luminous astrophysical bodies (LABs) can be rendered invisible with sufficient relativistic motion. This paper determines the proper distance as a function of relativistic velocity at which a luminous object attains ocular invisibility.

  1. Scattering coefficients and gray-body factor for 1D BEC acoustic black holes: Exact results

    Science.gov (United States)

    Fabbri, Alessandro; Balbinot, Roberto; Anderson, Paul R.

    2016-03-01

    A complete set of exact analytic solutions to the mode equation is found in the region exterior to the acoustic horizon for a class of 1D Bose-Einstein condensate acoustic black holes. From these, analytic expressions for the scattering coefficients and gray-body factor are obtained. The results are used to verify previous predictions regarding the behaviors of the scattering coefficients and gray-body factor in the low-frequency limit.

  2. Scattering coefficients and gray-body factor for 1D BEC acoustic black holes: exact results

    CERN Document Server

    Fabbri, Alessandro; Anderson, Paul R

    2015-01-01

    A complete set of exact analytic solutions to the mode equation are found in the region exterior to the acoustic horizon for a class of 1D Bose-Einstein condensate (BEC) acoustic black holes. From these, analytic expressions for the scattering coefficients and gray-body factor are obtained. The results are used to verify previous predictions regarding the behaviors of the scattering coefficients and gray-body factor in the low frequency limit.

  3. Accurate Waveforms for Non-spinning Binary Black Holes using the Effective-one-body Approach

    Science.gov (United States)

    Buonanno, Alessandra; Pan, Yi; Baker, John G.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.; vanMeter, James R.

    2007-01-01

    Using numerical relativity as guidance and the natural flexibility of the effective-one-body (EOB) model, we extend the latter so that it can successfully match the numerical relativity waveforms of non-spinning binary black holes during the last stages of inspiral, merger and ringdown. Here, by successfully, we mean with phase differences black-hole masses. The final black-hole mass and spin predicted by the numerical simulations are used to determine the ringdown frequency and decay time of three quasi-normal-mode damped sinusoids that are attached to the EOB inspiral-(plunge) waveform at the light-ring. The accurate EOB waveforms may be employed for coherent searches of gravitational waves emitted by non-spinning coalescing binary black holes with ground-based laser-interferometer detectors.

  4. Radiation from perfect mirrors starting from rest and accelerating forever and the black body spectrum

    CERN Document Server

    Calogeracos, A

    2002-01-01

    We address the question of radiation emission from a perfect mirror that starts from rest and follows the trajectory z=-ln(cosht) ad infinitum. We show that a correct derivation of the black body spectrum via the calculation of Bogolubov amplitudes requires consideration of the whole trajectory and not just of its asymptotic part.

  5. Radiation from perfect mirrors starting from rest and accelerating forever and the black body spectrum

    International Nuclear Information System (INIS)

    We address the question of radiation emission from a perfect mirror that starts from rest and follows the trajectory z=-ln(cosh t) until t→∞. We show that a correct derivation of the black body spectrum via the calculation of the Bogolubov amplitudes requires consideration of the whole trajectory and not just of its asymptotic part. (author)

  6. The black-body radiation inversion problem, its instability and a new universal function set method

    International Nuclear Information System (INIS)

    The black-body radiation inversion (BRI) problem is ill-posed and requires special techniques to achieve stable solutions. In this Letter, the universal function set method (UFS), is developed in BRI. An improved unique existence theorem is proposed. Asymptotic behavior control (ABC) is introduced. A numerical example shows that practical calculations are possible with UFS

  7. The Mirror of Television: A Comparison of Black and White Adolescents' Body Image.

    Science.gov (United States)

    Botta, Renee A.

    2000-01-01

    Finds that black adolescent girls were more satisfied with their bodies and had a larger personal ideal size than white adolescent girls, but engaged in no fewer eating-disordered behaviors and had no less drive to be thin; and these girls idealized television images equally and were as likely to compare themselves and their friends to television…

  8. Are Black-White Differences in Females' Body Dissatisfaction Decreasing? A Meta-Analytic Review

    Science.gov (United States)

    Roberts, Alan; Cash, Thomas F.; Feingold, Alan; Johnson, Blair T.

    2006-01-01

    Proponents of the sociocultural model of eating disorders have suggested that ethnic differences in body dissatisfaction may be diminishing as the thin ideal of beauty becomes more widely disseminated among minority women. In a meta-analysis, the authors examined temporal trends in Black-White differences and also examined whether these…

  9. She Had a Name That God Didn’t Give Her: Thinking the Body through Atheistic Black Radical Feminism

    OpenAIRE

    Marquis Bey

    2015-01-01

    The article attempts to demonstrate the necessity of acknowledging the body when considering the current Black Lives Matter movement, give an account of Black female and trans erasure, and ultimately (re)affirm the lived embodiment of Black, female, and trans bodies, all through an atheistic lens. Atheism here, while indeed denying the existence of gods, has as its primary concern affirming life. Too often is theology, as theologian Anthony Pinn says, “a theology of no-body”; thus atheistic f...

  10. Gender and race matter: the importance of considering intersections in Black women's body image.

    Science.gov (United States)

    Capodilupo, Christina M; Kim, Suah

    2014-01-01

    Traditionally, body image literature has used race as a variable to explain ethnic-specific differences in body satisfaction and the prevalence of eating disorders. Instead of employing race as an explanatory variable, the present study utilized a qualitative method to explore the relationships among race, ethnicity, culture, discrimination, and body image for African American and Black women. The purpose of the study was to gain a deeper understanding of how race and gender interface with and inform body image. Women were recruited through community centers in a major metropolitan city and represented a diversity of ethnicities. In total, 26 women who identified racially as Black (mean age = 26 years) participated in 6 focus groups, which explored body ideals, societal messages, cultural values, racism, and sexism. Narrative data from the focus groups were analyzed using grounded theory. The central category, Body/Self Image, was informed by perceptions of and feelings about not only weight and shape but also hair, skin, and attitude. Three additional categories, each with multiple properties, emerged: Interpersonal Influences, Experiences of Oppression, and Media Messages. These categories interact to explain the central category of Body/Self Image, and an emergent theory is presented. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24188651

  11. The absorbed dose in tooth enamel by 90SR body burden

    International Nuclear Information System (INIS)

    The residents of the villages along the Techa river, Southern Urals, Russia, were exposed mainly external by γ-rays from 137Cs and internal by γ-rays from 90Sr and its daughter 90Y, as a result of the heavy release of radioactive waste from the plutonium production facility Mayak into the Techa in 1950-51. The residents living at the lower part of the river were exposed only little externally but mainly internally due to their 90Sr body burden. Teeth from the latter group of residents which were extracted in 1994-95 in the course of dental care were collected and used for retrospective dosimetry more than 40 years after the main 90Sr ingestion. (author)

  12. She Had a Name That God Didn’t Give Her: Thinking the Body through Atheistic Black Radical Feminism

    Directory of Open Access Journals (Sweden)

    Marquis Bey

    2015-11-01

    Full Text Available The article attempts to demonstrate the necessity of acknowledging the body when considering the current Black Lives Matter movement, give an account of Black female and trans erasure, and ultimately (reaffirm the lived embodiment of Black, female, and trans bodies, all through an atheistic lens. Atheism here, while indeed denying the existence of gods, has as its primary concern affirming life. Too often is theology, as theologian Anthony Pinn says, “a theology of no-body”; thus atheistic feminist Blackness, as understood here, seeks to entrench the body rather than abstract it. Atheistic feminist Blackness reinscribes and affirms the subjectivity and humanity of Black, female, and trans bodies, countering hegemonic discourse that explicitly and implicitly states otherwise. The article’s emphasis of an atheistic posture stems from the prescient words of Catherine Keller: “atheist or agnostic feminists ignore the God-word at their own peril.” Therefore, the Black feminist ideological argument takes the “God-word” seriously, reckons with it, and offers an alternative to a theological tradition that often imbues the body with inherent flaw (sin, abstraction (soul, and erasure of the ontological value of Black, female, and noncisgendered bodies.

  13. N-Body Growth of a Bahcall-Wolf Cusp Around a Black Hole

    CERN Document Server

    Preto, M; Spurzem, R; Preto, Miguel; Merritt, David; Spurzem, Rainer

    2004-01-01

    We present a clear N-body realization of the growth of a Bahcall-Wolf f ~ E^0.25 (rho ~ 1/r^1.75) density cusp around a massive object ("black hole") at the center of a stellar system. Our N-body algorithm incorporates a novel implementation of Mikkola-Aarseth chain regularization to handle close interactions between star and black hole particles. Forces outside the chain were integrated on a GRAPE-6A/8 special-purpose computer with particle numbers up to N=0.25 x 10^6. We compare our N-body results with predictions of the isotropic Fokker-Planck equation and verify that the time dependence of the density (both configuration and phase-space) predicted by the Fokker-Planck equation is well reproduced by the N-body algorithm, for various choices of N and of the black hole mass. Our results demonstrate the feasibility of direct-force integration techniques for simulating the evolution of galactic nuclei on relaxation time scales.

  14. Black-body radiation effects and light shifts in atomic frequency standards

    International Nuclear Information System (INIS)

    A general method is presented for calculating the higher-order terms of series in powers of the black-body radiation field for the Stark-state wavefunctions, dipole transition matrix elements and corresponding frequency shifts of hyperfine splitting in the ground states for Cs and Rb atoms. A numerical method for calculating the light shifts in Sr atoms is described. It is based on the Green function method for summation over all intermediate states and exact Dirac-Fock wavefunctions for the resonant transitions to the first excited s-, p- and d-states. By comparing the calculated Stark shift with results of measurements employing atomic frequency standards, the black-body radiation effects on the ground state are analysed

  15. Redshifting of cosmological black bodies in BSBM varying-alpha theories

    CERN Document Server

    Barrow, John D

    2014-01-01

    We analyse the behaviour of black-body radiation in theories of electromagnetism which allow the electron charge and the fine structure constant to vary in space and time. We show that such theories can be expressed as relativistic generalizations of a conventional dielectric. By making the appropriate definition of the vector potential and associated gauge transformations, we can identify the equivalent of the electric and displacement fields, $\\mathbf{E}$ and $\\mathbf{D}$, as well as the magnetic $ \\mathbf{B}$ and $\\mathbf{H}$ fields. We study the impact of such dielectrics on the propagation of light in the so-called BSBM theory and conclude that no changes are created to the standard cosmological evolution of the temperature and energy-density of black-body radiation.

  16. Black-body laws derived from a minimum knowledge of Physics

    OpenAIRE

    A. G. AgneseINFN; La Camera, M.; E. Recami(INFN)

    2015-01-01

    Starting from the knowledge of the four fundamental quantities length L, mass M, time T, absolute temperature $\\theta$ and accepting the validity of Gauss's law in all dimensions, we generalize, by the theory of physical dimensions, the expression of the Stephan-Boltzmann law and of the Planck's formula for the black-body radiation to a spacetime with one time and n spatial coordinates. In the particular case n=3 we shall recover the known results.

  17. The Posthuman Body in Jennifer Egan’s “Black Box”

    Directory of Open Access Journals (Sweden)

    Precup Amelia

    2015-12-01

    Full Text Available This paper participates in the discussion about the configuration of what is commonly being referred to as ‘the posthuman condition’ by addressing the technological transformation of the human body and the cultural and political inflections of this transformation through the exploration of Jennifer Egan’s “Black Box.” The paper interrogates the implication of the fusion of flesh and technology and the re-conceptualization of the body as information, thus enabling insights into how these changes affect subjectivity, individuality, and the stereotyped understanding of gender hierarchies.

  18. Effects of Improvement for Carcass Quality on the Body Measurements and Reproductivity of Japanese Black Cows

    OpenAIRE

    Baco, Sudirman; Harada, Hiroshi; Fukuhara, Riichi

    1997-01-01

    Since the end of the 1970's, Wagyu producers in southern Kyushu have made efforts in order to improve not only carcass quantity but also carcass quality, introducing a number of AI sires which were produced in another districts that had a hight opinion on carcass quality. A study was conducted to examine effects of such an effort for carcass improvement on the body measurement and reproductivity of a local Japanese Black herd. The records of body measurements and reproductive traits of 1,189 ...

  19. Electrochemical deposition of black nickel solar absorber coatings on stainless steel AISI316L for thermal solar cells

    OpenAIRE

    Lira-Cantú, Monica; Morales Sabio, Angel; Brustenga, Alex; Gómez-Romero, P.

    2005-01-01

    We report the electrochemical deposition of nanostructured nickel-based solar absorber coatings on stainless steel AISI type 316L. A sol–gel silica-based antireflection coating, from TEOS, was also applied to the solar surface by the dip-coating method. We report our initial results and analyze the influence of the stainless steel substrate on the final total reflectance properties of the solar absorber. The relation between surface morphology, observed by SEM and AFM, the comp...

  20. Body and diet composition of sympatric black and grizzly bears in the Greater Yellowstone Ecosystem

    Science.gov (United States)

    Schwartz, Charles C.; Fortin, Jennifer K.; Teisberg, Justin E.; Haroldson, Mark A.; Servheen, Christopher; Robbins, Charles T.; van Manen, Frank T.

    2013-01-01

    The Greater Yellowstone Ecosystem (GYE) has experienced changes in the distribution and availability of grizzly bear (Ursus arctos) food resources in recent decades. The decline of ungulates, fish, and whitebark pine seeds (Pinus albicaulis) has prompted questions regarding their ability to adapt. We examined body composition and diet of grizzly bears using bioelectrical impedance and stable isotopes to determine if 1) we can detect a change in diet quality associated with the decline in either ungulates or whitebark pine, and 2) the combined decline in ungulates, fish, and pine seeds resulted in a change in grizzly bear carrying capacity in the GYE. We contrasted body fat and mass in grizzly bears with a potential competitor, the American black bear (Ursus americanus), to address these questions. Grizzly bears assimilated more meat into their diet and were in better body condition than black bears throughout the study period, indicating the decline in ungulate resources did not affect grizzly bears more than black bears. We also found no difference in autumn fat levels in grizzly bears in years of good or poor pine seed production, and stable isotope analyses revealed this was primarily a function of switching to meat resources during poor seed-producing years. This dietary plasticity was consistent over the course of our study. We did not detect an overall downward trend in either body mass or the fraction of meat assimilated into the diet by grizzly bears over the past decade, but we did detect a downward trend in percent body fat in adult female grizzly bears after 2006. Whether this decline is an artifact of small sample size or due to the population reaching the ecological carrying capacity of the Yellowstone ecosystem warrants further investigation.

  1. Spinning test-body orbiting around Schwarzschild black hole: circular dynamics and gravitational-wave fluxes

    CERN Document Server

    Harms, Enno; Bernuzzi, Sebastiano; Nagar, Alessandro

    2016-01-01

    We consider a spinning test-body in circular motion around a nonrotating black hole and analyze different prescriptions for the body's dynamics. We compare, for the first time, the Mathisson-Papapetrou formalism under the Tulczyjew spin-supplementary-condition (SSC), the Pirani SSC and the Ohashi-Kyrian-Semerak SSC, and the spinning particle limit of the effective-one-body Hamiltonian of [Phys.~Rev.~D.90,~044018(2014)]. We analyze the four different dynamics in terms of the ISCO shifts and in terms of the coordinate invariant binding energies, separating higher-order spin contributions from spin-orbit contributions. The asymptotic gravitational wave fluxes produced by the spinning body are computed by solving the inhomogeneous $(2+1)D$ Teukolsky equation and contrasted for the different cases. For small orbital frequencies $\\Omega$, all the prescriptions reduce to the same dynamics and the same radiation fluxes. For large frequencies, ${x \\equiv (M \\Omega)^{2/3} >0.1 }$, where $M$ is the black hole mass, and ...

  2. The use of India ink as an optical absorber in tissue-simulating phantoms

    International Nuclear Information System (INIS)

    The optical properties of phospholipid emulsions have been studied extensively but the optical properties of particulate absorbers, such as Indian Ink, have not been thoroughly investigated. A common and important assumption has been that ink acts as a perfect black-body absorber. The validity of this assumption is examined here. (author)

  3. Bodies in a Frame: Black British, Working Class, Teenage Femininity and the Role of the Dance Class

    OpenAIRE

    Camilla Stanger

    2013-01-01

    Historically the working class, black, female body has been defined by its sexuality and socially constructed as an object for heterosexual consumption; this article is concerned with how this manifests itself for young British women in educational settings today. I will argue that this historical bodily construction has been compounded for young women in this context by a contemporary popular culture which frames, glamorises and hetero-sexualises black female bodies. Drawing on the work of J...

  4. An Exploration of Body Dissatisfaction and Perceptions of Black and White Girls Enrolled in an Intervention for Overweight Children

    OpenAIRE

    Kelly, N. R.; Bulik, C. M.; Mazzeo, S. E.

    2011-01-01

    Silhouette measures are one approach to assessing body dissatisfaction in children, although little is known about their use among racially diverse, overweight girls seeking weight-loss treatment. This study assessed racial differences in body dissatisfaction and body size perceptions of 58 girls (ages 6–11, 66% Black, 34% White) participating in a randomized trial for pediatric overweight. Body dissatisfaction did not differ between races; 99% of girls reported an ideal figure smaller than t...

  5. Jarzynski equation for the expansion of a relativistic gas and black-body radiation

    Science.gov (United States)

    Nolte, Roman; Engel, Andreas

    2009-09-01

    Generalizing the work of Lua and Grosberg [R.C. Lua, A.Y. Grosberg, J. Phys. Chem. B 109 (2005) 6805], we verify the validity of the Jarzynski equation for the non-equilibrium expansion of an ideal relativistic gas and black-body radiation, respectively. The upper limit for the speed of the particles allows one to choose the parameters of the problem such that no multiple collisions need to be taken into account. Although related, the two cases considered differ from each other due to the quantum nature of photons. We show that bunching of photons is crucial for the Jarzynski equation to hold.

  6. Tidal disruption rate of stars by supermassive black holes obtained by direct N-body simulations

    CERN Document Server

    Brockamp, M; Kroupa, P

    2011-01-01

    The disruption rate of stars by supermassive black holes (SMBHs) is calculated numerically with a modified version of Aarseth's NBODY6 code. The initial stellar distribution around the SMBH follows a S\\'{e}rsic n=4 profile representing bulges and early type galaxies. In order to infer relaxation driven effects and to increase the statistical significance, a very large set of N-body integrations with different particle numbers N, ranging from 10^{3} to 0.5 \\cdot 10^{6} particles, is performed. Three different black hole capture radii are taken into account, enabling us to scale these results to a broad range of astrophysical systems with relaxation times shorter than one Hubble time, i.e. for SMBHs up to M_bh \\approx 10^{7} M_sun. The computed number of disrupted stars are driven by diffusion in angular momentum space into the loss cone of the black hole and the rate scales with the total number of particles as dN/dt \\propto N^{b}, where b is as large as 0.83. This is significantly steeper than the expected sc...

  7. The relationship between body mass index and self-concept among adolescent black female university students

    Directory of Open Access Journals (Sweden)

    P Bodiba

    2008-09-01

    Full Text Available The study investigated the relationship between body mass index and self-concept among adolescent black female university students. The study used a mixed research design (quantitative and qualitative methods. Media images of handsome faces and beautiful bodies are used to sell almost everything, from clothes and cosmetic to luncheon, meats, and so on. These images reinforce the western cultural stereotype that women should be thin and shapely to be attractive. Thus, as some girls go through puberty they may become dissatisfied with their weight, and to a lesser extent, with their shape, thus, developing low self-concept or imae of themselves. It is in this context that the study was conceptualised.

  8. Study of durability of (molybdenum-copper)-black coatings in relation to their use as solar selective absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Yousif, K.M.; Smith, B.E. (Brunel Univ., Uxbridge (United Kingdom)); Jeynes, C. (Surrey Univ., Guildford (United Kingdom). Dept. of Electronic and Electrical Engineering)

    1994-08-01

    In this work (Mo-Cu)-black coatings on Ni-plated Cu substrates have been prepared by electrodeposition. Their stability and durability has been investigated. The durability tests were carried out in two forms; accelerated ageing, and weathering. Reflectance measurements were used to evaluate both solar absorptance ([alpha]) and thermal emittance ([epsilon]) of the coatings. The coatings have been characterised before and after durability testing, using spectrophotometry together with other techniques, such as electron microscopy, X-rays, and ion beam. The main degradation modes of these coatings are loss of water, diffusion of metal atoms, and oxidation. (Mo-Cu)-black coatings undergo some changes in [alpha] and [epsilon] outdoor ageing. (Author)

  9. Irreducible decomposition of Gaussian distributions and the spectrum of black-body radiation

    International Nuclear Information System (INIS)

    It is shown that the energy of a mode of a classical chaotic field, following the continuous exponential distribution as a classical random variable, can be uniquely decomposed into a sum of its fractional part and of its integer part. The integer part is a discrete random variable (we call it the Planck variable) whose distribution is just the Bose distribution yielding Planck's law of black-body radiation. The fractional part is the 'dark part' represented by the 'dark variable' with a continuous distribution, which is, of course, not observed in the experiments. It is proved that the Bose distribution is infinitely divisible, and the irreducible decomposition of it is given. This means that the Planck variable can be decomposed into an infinite sum of independent binary random variables representing the 'binary photons' (more accurately photo-molecules or photo-multiplets) of energies 2shν with s=0, 1, 2, .... These binary photons follow Fermi statistics. According to our present analysis, the black-body radiation can be viewed as a mixture of statistically and thermodynamically independent fermion gases consisting of 'binary photons'. The binary photons give a natural tool for the dyadic expansion of arbitrary (but not coherent) ordinary photon excitations. It is shown that the binary photons have wave-particle fluctuations of fermions. These fluctuations combine to give the wave-particle fluctuations of the original bosonic photons, expressed by Einstein's fluctuation formula

  10. Dependence of the Black Body Force on Spacetime Geometry and Topology

    CERN Document Server

    Muniz, C R; Cunha, M S; Landim, R R; Filho, R N Costa

    2015-01-01

    In this manuscript we compute the corrections to the black body force due to spacetime geometry and topology. This recently discovered attractive force on neutral atoms is caused by the thermal radiation emitted from black bodies and here we investigate it in systems with spherical and cylindrical symmetries. For some astrophysical objects we find that the corrected force is greater than the flat case, showing that this kind of correction can be quite relevant when curved spaces are considered. Then we consider four cases: The Schwarzschild spacetime, the non-relativistic infinity cylinder, and both the static and stationary cosmic strings. For the spherically symmetric case we find that two corrections appear: One due to the gravitational modification of the temperature and the other due to the modification of the solid angle subtended by the atom. We apply the found results to a typical neutron star and to the Sun. For the cylindrical case, which is locally flat, no gravitational correction to the temperatu...

  11. Antler and Body Size in Black-Tailed Deer: An Analysis of Cohort Effects

    Directory of Open Access Journals (Sweden)

    Johanna C. Thalmann

    2015-01-01

    Full Text Available For long-lived species, environmental factors experienced early in life can have lasting effects persisting into adulthood. Large herbivores can be susceptible to cohort-wide declines in fitness as a result of decreases in forage availability, because of extrinsic factors, including extreme climate or high population densities. To examine effects of cohort-specific extrinsic factors on size of adults, we performed a retrospective analysis on harvest data of 450 male black-tailed deer (Odocoileus hemionus columbianus over 19 years in central California, USA. We determined that population density of females had a more dominant effect than did precipitation on body size of males. Harvest of female deer resulted in increases in the overall size of males, even though a 6-year drought occurred during that treatment period. Body size was most influenced by female population density early in life, while antler size was highly affected by both weather early in life and the year directly before harvest. This study provides insights that improve our understanding of the role of cohort effects in body and antler size by cervids; and, in particular, that reduction in female population density can have a profound effect on the body and antler size of male deer.

  12. Energy Crisis in Astrophysics (Black Holes vs. N-Body Metrics)

    CERN Document Server

    Alley, C O; Mizobuchi, Y; Yilmaz, H; Alley, Carroll O; Leiter, Darryl L; Mizobuchi, Yutaka; Yilmaz, Huseyin

    1999-01-01

    The recent observation of the gamma ray burster GRB 990123, requiring at least two solar masses of energy in gamma radiation alone, created an energy crisis in astrophysics (Schilling 1999). We discuss a theorem which states that, of all four-dimensional curved spacetime theories of gravity viable with respect to the four classical weak field tests, only one unique case, the Yilmaz theory, has interactive N-body (multiparticle) solutions and this unique case has no event horizons. The theorem provides strong theoretical support for Robertson's explanation of the large energy output of the gamma ray burster GRB 990123 (Robertson 1999b). This explanation requires a switch from black holes (a 1-body solution with horizon) to the case of horizon-free interactive N-body solutions. In addition to the good news that the long sought N-body solutions are found, this unique case enjoys further strong support from other areas of gravitational physics. This development does not rule out GRB models with beaming, which can...

  13. The Politics of “Being Too Fast”: Policing Urban Black Adolescent Female Bodies, Sexual Agency, Desire, and Academic Resilience

    OpenAIRE

    Stevenson, Stephanie Y

    2012-01-01

    Culturally produced dominant representations and discourses mark low-income, urban black girls’ bodies, thoughts, and actions as “fast (i.e. sexually promiscuous). This punitive label enforces regulatory systems where the girls can be policed and reprimanded. This paper closely examines political narratives, policies, ethnographic data from focus groups with urban black Baltimorean middle school girls, and online coverage of a Baltimore City teen school sex scandal. The author uses an interse...

  14. “My Body the Lesson”: Queering Black Women’s Subjectivities in The Street and Symptomatic

    OpenAIRE

    Quinn, Rachel Afi

    2008-01-01

    As twentieth-century black women writers, Ann Petry and Danzy Senna have used the form of the novel to construct multifaceted black women’s subjectivities through what Mae Henderson refers to as “simultaneity of discourse”. By including characters in their novels that inhabit non-normative bodies, both Petry with The Street(1946) and Senna with Symptomatic(2004) expand our notions of what it means to be female and black. This paper will theorize the “queer of color” identities of two particu...

  15. Graphene and carbon black nano-composite polymer absorbers for a pyro-electric solar energy harvesting device based on LiNbO3 crystals

    International Nuclear Information System (INIS)

    Highlights: • A novel scheme for solar energy harvesting based on pyroelectric effect is proposed. • An optical system focusing solar radiation onto a LiNbO3 crystal is used. • Graphene and carbon black nano-composite polymer absorbers used as coating. • This configuration increases the amplitude of temperature variation experienced. • The whole solar spectrum is involved in the energy harvesting mechanism. - Abstract: A novel scheme for solar energy harvesting based on the pyro-electric effect has been demonstrated. The proposed harvester is based on an optical system focusing solar radiation onto a ferroelectric crystal (i.e. lithium niobate). The face exposed to the heating source is coated with a nanocomposite material (i.e. carbon black and graphene particles) that greatly improves the adsorption of solar radiation. The solar energy focused onto the crystal through a simple optical system allows one to induce a thermal gradient able to generate electric charges. Experiments have been carried out indoor as well as outdoor (in Pozzuoli, Naples, Italy, on December). Results show that two configurations appear to be preferable: (a) pyro-electric element with carbon black-based coating and a Fresnel lens (surface of about 100 cm2); (b) pyro-electric element with graphene-based coating and a Fresnel lens (surface of about 600 cm2). In both experimental arrangements the maximum temperature variation reached locally onto the lithium niobate substrate is relatively high with peaks greater than 250 °C. The maximum electrical power peak is of about 90 μW and about 50 μW for (a) and (b) respectively. The results of this first investigation are encouraging for further development of more efficient harvesting devices

  16. Measurement of neutron and gamma-ray absorbed doses inside human body in criticality accident situations using phantom and tissue-equivalent dosimeters

    International Nuclear Information System (INIS)

    Personal dosimeters provide a fundamental evaluation of external exposures to human bodies in radiation accidents. For emergency medical treatment to heavily exposed patients, the evaluation of dose distribution inside the body has been tried by computational simulations. Experimental data on dose distributions inside the body are necessary for accurate simulation of human dosimetry, particularly in complex radiation fields of neutrons and gamma-rays such as criticality accidents. A preliminary experiment on the human dosimetry was carried out at the Transient Experiment Critical Facility (TRACY) to acquire such experimental data in criticality accident situations. A combined use of two kinds of tissue-equivalent dosimeters together with a human phantom was employed to measure neutron and gamma-ray absorbed doses inside the body. The neutron and gamma-ray absorbed doses measured on the phantom were found to be in roughly the same level as those averaged over the phantom inside or those measured in free air. The dose distributions measured inside and on the phantom could be qualitatively interpreted from reflection an attenuation of neutrons and gamma-rays in the phantom, neutron-induced secondary gamma-rays emitted in the phantom, and so forth. (author)

  17. Hydrodynamics of triangular-grid arrays of floating point-absorber wave energy converters with inter-body and bottom slack-mooring connections

    Energy Technology Data Exchange (ETDEWEB)

    Vicente, Pedro C.; Falcao, Antonio F. de O.; Gato, Luiz M.C. [IDMEC, Instituto Superior Tecnico, Technical University of Lisbon, 1049-001 Lisboa (Portugal); Justino, Paulo A.P. [Laboratorio Nacional de Energia e Geologia, 1649-038 Lisboa (Portugal)

    2009-07-01

    It may be convenient that dense arrays of floating point absorbers are spread-moored to the sea bottom through only some of their elements (possibly located in the periphery), while the other array elements are prevented from drifting and colliding with each other by connections to adjacent elements. An array of identical floating point absorbers located at the grid points of an equilateral triangular grid is considered in the paper. A spread set of slack-mooring lines connect the peripheric floaters to the bottom. A weight is located at the centre of each triangle whose function is o pull the three floaters towards each other and keep the inter-body moorings lines under tension. The whole system - buoys, moorings and power take-off systems - is assumed linear, so that a frequency domain analysis may be employed. Hydrodynamic interference between the oscillating bodies is neglected. Equations are presented for a set of three identical point absorbers. This is then extended to more complex equilateral iriangular grid arrays. Results from numerical simulations, with regular and irregular waves, are presented for the motions and power absorption of hemispherical converters in arrays of three and seven elements and different mooring and power take-off parameters, and wave incidence angles. Comparisons are given with the unmoored and independently-moored buoy situations.

  18. The relationship between body mass index and self-concept among adolescent black female university students.

    Science.gov (United States)

    Bodiba, P; Madu, S N; Ezeokana, J O; Nnedum, O A U

    2008-03-01

    The study investigated the relationship between body mass index and self-concept among adolescent black female university students. The study used a mixed research design (quantitative and qualitative methods). Media images of handsome faces and beautiful bodies are used to sell almost everything, from clothes and cosmetic to luncheon, meats, and so on. These images reinforce the western cultural stereotype that women should be thin and shapely to be attractive. Thus, as some girls go through puberty they may become dissatisfied with their weight, and to a lesser extent, with their shape, thus, developing low self-concept or imae of themselves. It is in this context that the study was conceptualised. First year female students from three different Schools and Faculties at the University of Limpopo, Turfloop Campus, South Africa, participated in the study. Using the availability and convenient sampling method, 75 students were selected for this study. For the quantitative aspect of the study, the Rosenberg Self-esteem Measure was used to measure self-esteem. For the qualitative part, a topic guide was used for the focus group discussions. Analysis of Variance (ANOVA) and the Pearson's Product Moment Correlation were used to analyse the quantitative data, while the phenomenological principle of open coding used for the thematic analysis. Results showed that there is a relationship between body mass and self-concept and that overweight participants tend to have a low self-esteem. Low self-esteem was perceived to be aggravated by a number of factors, like the attitude of the media and the society. Participants who are overweight also indicated that they are limited in certain activities of daily living (e.g., sports) as a result of their body mass. They expressed mixed feelings and frustration when it comes to such activities. The above results did not differ from those reported from western cultures. Support groups, life-skills programmes and psychotherapy should be

  19. PREDICTION OF CARCASS TRAITS OF JAPANESE BLACK BULLS AT SEVERAL AGES USING BODY MEASUREMENTS AND ULTRASONIC ESTIMATE OF CARCASS TRAITS

    OpenAIRE

    Sri Rachma, Aprilita Bugiwati

    2008-01-01

    The present research aims to estimate the mathematical equations for predicting ultrasonic estimates of carcass traits at ten months after performance test (about 20 months of age) using body measurements and ultrasonic estimates of carcass traits at earlier stages of performance test of Japanese Black bulls. This research was done at Kagoshima and Miyazaki prefecture Livestock Experimental Stations Japan to collect the ultrasonic estimates of carcass traits and body measurements data of Jap...

  20. Inequalities Between Size and Charge for Bodies and the Existence of Black Holes Due to Concentration of Charge

    CERN Document Server

    Khuri, Marcus A

    2015-01-01

    A universal inequality that bounds the charge of a body by its size is presented, and is proven as a consequence of the Einstein equations in the context of initial data sets which satisfy an appropriate energy condition. We also present a general sufficient condition for the formation of black holes due to concentration of charge, and discuss the physical relevance of these results.

  1. Effect of black pepper (piper nigrum) on body weight and some serum lipid fractions in whole body gamma irradiated albino rats

    International Nuclear Information System (INIS)

    Two experiments were conducted to determine effect of sublethal body gamma irradiation (6.0 Gy as a single dose) on body weight and some serum lipid fractions in female and male rats. The beneficial efficacy of intragastric administration of black pepper (in two doses of 160 and 320 mg/kg bw) was also investigated. The results obtained revealed that the sublethal irradiated rats showed a drastic loss in body weight reached 39.5% less than the normal males and significant alterations in serum triglycerides, cholesterol, high density lipoprotein (HDL-cholesterol) and low density lipoprotein (LDL-cholesterol) levels, 5 weeks post exposure to gamma irradiation in female and male rats. Black pepper showed a beneficial effect on these significant changes in lipid fractions in irradiated female and male rats. Treatment with the two doses of black pepper up to 14 weeks, 5 days/week, showed a slight effect on body gain and fluctuations in the lipid fractions at 5.10 and 14 weeks for both sexes

  2. Forcing culture of 'Black beauty'-type eggplant [Solanum melongena] 'Kurowashi' under near-ultraviolet radiation absorbing vinyl film

    International Nuclear Information System (INIS)

    In a forcing culture of the 'Black Beauty'- type eggplant 'Kurowashi' (Solanum melongena var. esculentum (L.) Nees), comparisons were made in respect to growth and yield under near-ultraviolet radiation-100% absorbing vinyl film (UV100 film), and those under standard greenhouse vinyl film (standard film). Investigations were also made on the influence of the number of shoots and planting density. 1. Under UV100 film, shoot growth was the same as under standard film. The total number of flowers was somewhat increased, but the rate of harvested fruit decreased, and the yield of marketable fruit was less. On the other hand, there was little difference in the color of leaves or fruit skins; however, the green color of the shoots was lighter. 2. Under the UV100 film, when the planting system used a 180cm ridge width and a single row, the yield of marketable fruit with 2 shoots training (1,389 stocks/10a) was more than 4 shoots training (694 stocks/10a), when the numbers of shoots per unit area were the same. Moreover, with the 2 shoots training, the yield of marketable fruit for the 35cm intra-row spacing (1,587 stocks/10a) was more than the 40cm intra-row spacing (1,389 stocks/10a)

  3. The association of perceived stress, contextualized stress, and emotional eating with body mass index in college-aged Black women.

    Science.gov (United States)

    Diggins, Allyson; Woods-Giscombe, Cheryl; Waters, Sandra

    2015-12-01

    A growing body of literature supports the association between adverse stress experiences and health inequities, including obesity, among African American/Black women. Adverse stress experiences can contribute to poor appetite regulation, increased food intake, emotional eating, binge eating, and sedentary behavior, all of which can contribute to weight gain and obesity. Most research studies concerning the effect of psychological stress on eating behaviors have not examined the unique stress experience, body composition, and eating behaviors of African American/Black women. Even fewer studies have examined these constructs among Black female college students, who have an increased prevalence of overweight and obesity compared to their counterparts. Therefore, the aim of the current study is to examine the associations among emotional eating, perceived stress, contextualized stress, and BMI in African American female college students. All participants identified as African American or Black (N=99). The mean age of the sample was 19.4 years (SD=1.80). A statistically significant eating behavior patterns×perceived stress interaction was evident for body mass index (BMI) (β=0.036, S.E.=.0118, pstress interaction was observed for BMI (β=0.007, S.E.=.0027, p=.015). Findings from this study demonstrate that the stress experience interacts with emotional eating to influence BMI. Based on these findings, culturally relevant interventions that target the unique stress experience and eating behavior patterns of young African American women are warranted. PMID:26496005

  4. Linking food availability, body growth and survival in the black-legged kittiwake Rissa tridactyla

    Science.gov (United States)

    Vincenzi, Simone; Mangel, Marc

    2013-10-01

    Population dynamics of black-legged kittiwakes Rissa tridactyla in Bering Sea colonies are likely to increasingly experience climate-induced changes in the physical environment. Since adult kittiwakes are central place foragers with high energy requirements, increased variability of forage patch dynamics, as predicted for polar regions, may influence both quantity and quality of food available and consequently alter the population dynamics of kittiwake colonies. Here, we describe, conceptualize, and model the effects of environment and energy resources on kittiwake growth, fledging age (from 35 to 50 days) and survival from hatching up to first breeding (post-hatching productivity). For our life-history model, we use a von Bertalanffy growth function for body growth in mass. We model nestling mortality as a function of somatic growth, in order to account for oxidative damage and trade-offs in the allocation of resources, and energy available, since low food availability increases the risk of chicks' starvation and predation risk. In the case of a good environment (i.e., high food availability), the best strategy (i.e., highest post-hatching productivity) is to grow fast (about 18.6 g d-1) and to spend a moderately long time in the nest (up to 45 days), while in the case of a poor environment the best strategy is to grow fast (about 18 g d-1) and leave the nest soon (35-40 days). Different ages at first breeding do not change the optimal strategies. We discuss the implications of optimal growth strategy in terms of evolution of life histories in kittiwakes and how our work, coupled with models of post-breeding survival and reproductive dynamics, could lead to the development of a full life-history model and the exploration of future evolutionary trajectories for traits like body growth and age at first breeding.

  5. Whole-body biodistribution, radiation absorbed dose, and brain SPET imaging with [123I]5-I-A-85380 in healthy human subjects

    International Nuclear Information System (INIS)

    The biodistribution of radioactivity after the administration of a new tracer for α4β2 nicotinic acetylcholine receptors (nAChRs), [123I]5-iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380), was studied in ten healthy human subjects. Following administration of 98±6 MBq [123I]5-I-A-85380, serial whole-body images were acquired over 24 h and corrected for attenuation. One to four brain single-photon emission tomography (SPET) images were also acquired between 2.5 and 24 h. Estimates of radiation absorbed dose were calculated using MIRDOSE 3.1 with a dynamic bladder model and a dynamic gastrointestinal tract model. The estimates of the highest absorbed dose (μGy/MBq) were for the urinary bladder wall (71 and 140), lower large intestine wall (70 and 72), and upper large intestine wall (63 and 64), with 2.4-h and 4.8-h urine voiding intervals, respectively. The whole brain activity at the time of the initial whole-body imaging at 14 min was 5.0% of the injected dose. Consistent with the known distribution of α4β2 nAChRs, SPET images showed the highest activity in the thalamus. These results suggest that [123I]5-I-A-85380 is a promising SPET agent to image α4β2 nAChRs in humans, with acceptable dosimetry and high brain uptake. (orig.)

  6. Validating the effective-one-body model of spinning, precessing binary black holes against numerical relativity

    CERN Document Server

    Babak, Stanislav; Buonanno, Alessandra

    2016-01-01

    In Ref. [1], the properties of the first gravitational wave detected by LIGO, GW150914, were measured by employing an effective-one-body (EOB) model of precessing binary black holes whose underlying dynamics and waveforms were calibrated to numerical-relativity (NR) simulations. Here, we perform the first extensive comparison of such EOBNR model to 70 precessing NR waveforms that span mass ratios from 1 to 5, dimensionless spin magnitudes up to 0.5, generic spin orientations, and length of about 20 orbits. We work in the observer's inertial frame and include all $\\ell=2$ modes in the gravitational-wave polarizations. We introduce new prescriptions for the EOB ringdown signal concerning its spectrum and time of onset. For total masses between 10Msun and 200Msun, we find that precessing EOBNR waveforms have unfaithfulness within about 3% to NR waveforms when considering the Advanced-LIGO design noise curve. This result is obtained without recalibration of the inspiral-plunge of the underlying nonprecessing EOBN...

  7. Improved approximate inspirals of test-bodies into Kerr black holes

    CERN Document Server

    Gair, J R; Gair, Jonathan R; Glampedakis, Kostas

    2006-01-01

    We present an improved version of the approximate scheme for generating inspirals of test-bodies into a Kerr black hole recently developed by Glampedakis, Hughes and Kennefick. Their original "hybrid" scheme was based on combining exact relativistic expressions for the evolution of the orbital elements (the semi-latus rectum p and eccentricity e) with approximate, weak-field, formula for the energy and angular momentum fluxes, amended by the assumption of constant inclination angle, iota, during the inspiral. Despite the fact that the resulting inspirals were overall well-behaved, certain pathologies remained for orbits in the strong field regime and for orbits which are nearly circular and/or nearly polar. In this paper we eliminate these problems by incorporating an array of improvements in the approximate fluxes. Firstly, we add certain corrections which ensure the correct behaviour of the fluxes in the limit of vanishing eccentricity and/or 90 degrees inclination. Secondly, we use higher order post-Newton...

  8. Numerical models of black body dominated GRBs: I. Hydrodynamics and the origin of the thermal emission

    CERN Document Server

    Cuesta-Martínez, Carlos F; Mimica, Petar

    2014-01-01

    We extend an existing theoretical model to explain the class of Black-Body Dominated GRBs, namely long lasting events characterized by the presence of a notable thermal component trailing the GRB prompt emission, and a rather weak traditional afterglow. GRB 101225A, the Christmas Burst (CB), is a prototype of such class. It has been suggested that BBD-GRBs could result from the merger of a binary system formed by a neutron star and the Helium core of a main sequence star. We have modeled the propagation of ultrarelativistic jets through the environment left behind the merger by means of detailed relativistic hydrodynamic numerical simulations. In this paper, the output of our numerical models is further postprocessed to obtain the (thermal) radiative signature of the resulting outflow. The complete (thermal and non-thermal) output of our models is considered in a companion contribution. Here, we outline the most relevant dynamical details of the jet propagation and connect them to the generation of thermal ra...

  9. Constraining the redshift evolution of the Cosmic Microwave Background black-body temperature with PLANCK data

    CERN Document Server

    de Martino, I; Atrio-Barandela, F; Ebeling, H; Kashlinsky, A; Kocevski, D; Martins, C J A P

    2015-01-01

    We constrain the deviation of adiabatic evolution of the Universe using the data on the Cosmic Microwave Background (CMB) temperature anisotropies measured by the {\\it Planck} satellite and a sample of 481 X-ray selected clusters with spectroscopically measured redshifts. To avoid antenna beam effects, we bring all the maps to the same resolution. We use a CMB template to subtract the cosmological signal while preserving the Thermal Sunyaev-Zeldovich (TSZ) anisotropies; next, we remove galactic foreground emissions around each cluster and we mask out all known point sources. If the CMB black-body temperature scales with redshift as $T(z)=T_0(1+z)^{1-\\alpha}$, we constrain deviations of adiabatic evolution to be $\\alpha=-0.007\\pm 0.013$, consistent with the temperature-redshift relation of the standard cosmological model. This result could suffer from a potential bias associated with the CMB template, that we quantify it to be less than $-0.02$, but is free from those biases associated with using TSZ selected ...

  10. Accurate Effective-One-Body waveforms of inspiralling and coalescing black-hole binaries

    CERN Document Server

    Damour, Thibault; Hannam, Mark; Husa, Sascha; Brugmann, Bernd

    2008-01-01

    The Effective-One-Body (EOB) formalism contains several flexibility parameters, notably $a_5$, $\\vp$ and $\\a$. We show here how to jointly determine the values of these parameters by simultaneously best-fitting the EOB waveform to two, independent, numerical relativity (NR) simulations of inspiralling and/or coalescing binary black hole systems: published Caltech-Cornell {\\it inspiral} data on one side and newly computed {\\it coalescence} data on the other side. The resulting, essentially unique, ``best-fit'' EOB waveform is then shown to exhibit excellent agreement with NR coalescence data for several mass ratios. The dephasing between EOB and published Caltech-Cornell inspiral data is found to be smaller than $\\pm 2\\times 10^{-4}$ gravitational wave cycles over the entire span ($\\sim 3000M$, corresponding to 30 cycles) of the inspiral simulation. The dephasings between EOB and the new coalescence data are found to be smaller than: (i) $\\pm 4\\times 10^{-3}$ gravitational wave cycles over $730M$ (11 cycles), ...

  11. Crashworthy Energy Absorbing Car-body Design Method for Pass enger Train%客运列车耐冲击吸能车体设计方法

    Institute of Scientific and Technical Information of China (English)

    田红旗

    2001-01-01

    In order to reduce the losses suffered from collision between passenger trains,a new design method for the car body structure of motor car and trailer is advanced.Car body structures are made up of three parts with diffferen tstiffness,by carefully designed.The parts of the front and the end are the wea kstiffness structure to absorb energy through plastic deformation in the collision.The middle part,where only elastic deformation occurs,is an elastic deformati on structure with strong stiffness.As the passenger train runs normally,car body structure measure up to regulation of intensity and stiffness in the standards. Once collision accident occurred when the train is moving with fairly high speed ,the energy-absorbing structure produces large plastic deformation along the direction needed to absorb sufficient energy,at the same time,the deceleration must be controlled within the endurable limits to human body.%为了减轻客运列车碰撞事故造成的损失,实现被动安全保护,对组成列车的动车、客车车体结构提出了新的设计方法,重新分配车体各部分刚度,设计出具有合适吸能结构的耐冲击车体,车体结构均按前、中、后三种纵向刚度设置,前后 两部分为可以产生塑性变形的弱刚度吸能结构,中间部分为仅产生弹性变形的强刚度弹变结 构。当列车在正常运行时,车体有足够的强度和刚度,需要满足有关规范规定的强度、刚度 要求;在较高速下发生碰撞事故时,吸能结构能够沿所需方向产生塑性大变形吸收足够冲击 动能,保证机器间和乘客区不发生破坏,并延缓碰撞作用时间,降低碰撞瞬间最大减速度,使撞击减速度在人体承受范围内。

  12. Additive Effects of Anxiety and Depression on Body Mass Index among Blacks: Role of Ethnicity and Gender

    Directory of Open Access Journals (Sweden)

    Shervin Assari

    2014-06-01

    Full Text Available Background:: Most studies on mental health associates of obesity have focused on depression and less is known about the role of anxiety in obesity.. Objectives:: This study compared the additive effects of General Anxiety Disorder (GAD and Major Depressive Disorder (MDD on Body Mass Index (BMI across sub-populations of Blacks based on the intersection of ethnicity and gender.. Methods:: Data came from the National Survey of American Life (NSAL, 2001 - 2003. The participants consisted of 3,570 African Americans and 1,621 Caribbean Blacks. Twelve-month MDD and GAD were determined using the World Mental Health Composite International Diagnostic Interview (CIDI. Levels of BMI were categorized based on being equal to or larger than 25, 30, 35, and 40 kg/m2. We fitted linear regression models specific for our groups, which were defined based on the intersection of ethnicity and gender. Additionally, age, education, marital status, employment, and region were controlled.. Results:: Among Caribbean Black men and African American women, lifetime GAD, but not MDD, was associated with high BMI. Among Caribbean Black women, lifetime MDD, but not GAD, was associated with high BMI.. Conclusions:: Intersection of ethnicity and gender may determine how anxiety and depression are associated with BMI among Blacks. Sub-populations of Blacks (e.g. based on ethnicity and gender may have specific mental health determinants or consequences of obesity. Future research should investigate how and why the additive effects of anxiety and depression on obesity vary across ethnic and gender groups of Blacks..

  13. Effect of weight fraction of carbon black and number of plies of E-glass fiber to reflection loss of E-glass/ripoxy composite for radar absorbing structure (RAS)

    Science.gov (United States)

    Widyastuti, Ramadhan, Rizal; Ardhyananta, Hosta; Zainuri, Mochamad

    2013-09-01

    Nowadays, studies on investigating radar absorbing structure (RAS) using fiber reinforced polymeric (FRP) composite materials are becoming popular research field because the electromagnetic properties of FRP composites can be tailored effectively by just adding some electromagnetic powders, such as carbon black, ferrite, carbonyl iron, and etc., to the matrix of composites. The RAS works not only as a load bearing structure to hold the antenna system, but also has the important function of absorbing the in-band electromagnetic wave coming from the electromagnetic energy of tracking systems. In this study, E-glass fiber reinforced ripoxy resin composite was fabricated by blending the conductive carbon black (Ketjenblack EC300J) with the binder matrix of the composite material and maximizing the coefficient of absorption more than 90% (more than -10 dB) within the X-band frequency (8 - 12 GHz). It was measured by electrical conductivity (LCR meter) and vector network analyzer (VNA). Finally, the composite RAS with 0.02 weight fraction of carbon black and 4 plies of E-glass fiber showed thickness of 2.1 mm, electrical conductivity of 8.33 × 10-6 S/m, and maximum reflection loss of -27.123 dB, which can absorb more than 90% of incident EM wave throughout the entire X-band frequency range, has been developed.

  14. One size does not fit all: using variables other than the thin ideal to understand Black women's body image.

    Science.gov (United States)

    Capodilupo, Christina M

    2015-04-01

    Very few empirical studies have investigated the effect that culturally relevant beauty ideals (such as long, straight hair and lighter skin tones) have on Black women's feelings about their physical appearance. The current investigation examined the direct effect of internalizing idealized media images on Black women's body esteem and appearance satisfaction. The indirect effects of: (a) the presumed influence of the media images on African American men, and (b) feelings of invisibility were also tested. Using an online survey, the sample included 230 women who identified as African American and/or Black American. Through structural equation modeling (SEM), findings reveal that participants' body esteem was directly negatively impacted by higher levels of internalization of idealized media images. Further, the findings support the idea that higher levels of internalization of media lead to a greater presumed influence of media on men, which leads to higher feelings of invisibility, ultimately leading to lower body esteem. Finally, there was evidence to suggest that appearance satisfaction was not directly negatively affected by internalization of media images but was negatively impacted when the images are presumed to have a higher influence on African American men. PMID:25150817

  15. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    Science.gov (United States)

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-11-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform.

  16. Overcoming the black body limit in plasmonic and graphene near-field thermophotovoltaic systems.

    Science.gov (United States)

    Ilic, Ognjen; Jablan, Marinko; Joannopoulos, John D; Celanovic, Ivan; Soljacić, Marin

    2012-05-01

    Near-field thermophotovoltaic (TPV) systems with carefully tailored emitter-PV properties show large promise for a new temperature range (600 – 1200K) solid state energy conversion, where conventional thermoelectric (TE) devices cannot operate due to high temperatures and far-field TPV schemes suffer from low efficiency and power density. We present a detailed theoretical study of several different implementations of thermal emitters using plasmonic materials and graphene. We find that optimal improvements over the black body limit are achieved for low bandgap semiconductors and properly matched plasmonic frequencies. For a pure plasmonic emitter, theoretically predicted generated power density of 14 W/cm2 and efficiency of 36% can be achieved at 600K (hot-side), for 0.17eV bandgap (InSb). Developing insightful approximations, we argue that large plasmonic losses can, contrary to intuition, be helpful in enhancing the overall near-field transfer. We discuss and quantify the properties of an optimal near-field photovoltaic (PV) diode. In addition, we study plasmons in graphene and show that doping can be used to tune the plasmonic dispersion relation to match the PV cell bangap. In case of graphene, theoretically predicted generated power density of 6(120) W/cm2 and efficiency of 35(40)% can be achieved at 600(1200)K, for 0.17eV bandgap. With the ability to operate in intermediate temperature range, as well as high efficiency and power density, near-field TPV systems have the potential to complement conventional TE and TPV solid state heat-to-electricity conversion devices. PMID:22712094

  17. Determination of absorbed dose in body inhomogeneities such as lung, bone and fat tissue for neutron therapy

    International Nuclear Information System (INIS)

    Dose distribution calculations for an 'inhomogeneous' patient have been performed for cyclotron and 14 MeV neutron therapy facilities using radiation transport programs. Precise dose determination in the patient is very important for the success of neutron therapy. The results were evaluated and transformed into inhomogeneity correction factors appropriate for treatment-planning code systems. The kerma distribution is represented by an analytical formula. For each kind of tissue two inhomogeneity correction factors are needed; these transform the neutron and gamma dose measured in a homogeneous water phantom by a tissue-equivalent detector to the specific values of the patient. The first correction factor adjusts the water attenuation coefficient in the exponential part of the dose formula to that of the patient, and the second factor corrects the kerma from TE gas to the particular human tissue being considered. It is the second factor that is responsible for the jump or discontinuity in the absorbed dose of about 25% between soft tissue and bone or for the 14% increase of kerma in fat tissue. Various sets of inhomogeneity factors were provided, and these are stored in tabular form in the code. The external and internal contours of a patient can be derived from CT images. The user of the code has to identify the kind of tissue for each inhomogeneity volume using a specified code name. Additionally, individual CT numbers can be supplied to characterize, for example, the density and mineral content of bone, the density and water content of the lung, or the density and fat content of critical skin regions. According to the CT number given, fine adjustments of the correction factors can be used to describe the inhomogeneity effects individually for each patient. (author)

  18. Transient fluid-structure interaction of elongated bodies by finite-element method using elliptical and spheroidal absorbing boundaries

    Science.gov (United States)

    Bhattacharyya, S. K.; Premkumar, R.

    2003-12-01

    In a domain method of solution of exterior scalar wave equation, the radiation condition needs to be imposed on a truncation boundary of the modeling domain. The Bayliss, Gunzberger, and Turkel (BGT) boundary dampers, which require a circular cylindrical and spherical truncation boundaries in two-(2D) and three-(3D)-dimensional problems, respectively, have been particularly successful in the analysis of scattering and radiation problems. However, for an elongated body, elliptical (2D) or spheroidal (3D) truncation boundaries have potential to reduce the size of modeling domain and hence computational effort. For harmonic problems, such extensions of the first- and second-order BGT dampers are available in the literature. In this paper, BGT dampers in both elliptical and spheroidal coordinate systems have been developed for transient problems involving acoustic radiation as well as fluid-structure interaction and implemented in the context of finite-element method based upon unsymmetric pressure-displacement formulation. Applications to elongated radiators and shells are reported using several numerical examples with excellent comparisons. It is demonstrated that significant computational economy can be achieved for elongated bodies with the use of these dampers.

  19. DOSE-Analyzer. A computer program with graphical user interface to analyze absorbed dose inside a body of mouse and human upon external neutron exposure

    International Nuclear Information System (INIS)

    DOSE-Analyzer is a computer program to retrieve the dose information from a database and generate a graph through a graphical user interface (GUI). The database is constructed for absorbed dose, fluence, and energy distribution inside a body of mouse and human exposed upon external neutrons, which is calculated by our developed Monte-Carlo simulation method using voxel-based phantom and particle transport code PHITS. The input configurations of irradiation geometry, subject, and energy are set by GUI. The results are tabulated at particle types, i.e. electron, proton, deuteron, triton, and alpha particle, and target organs on a data sheet of Microsoft Office ExcelTM. Simple analysis to compare the output values for two subjects is also performed on DOSE-Analyzer. This report is a user manual of DOSE-Analyzer. (author)

  20. Binary black hole coalescence in the extreme-mass-ratio limit: testing and improving the effective-one-body multipolar waveform

    CERN Document Server

    Bernuzzi, Sebastiano; Zenginoglu, Anil

    2010-01-01

    We discuss the properties of the effective-one-body (EOB) multipolar gravitational waveform emitted by nonspinning black-hole binaries of masses $\\mu$ and $M$ in the extreme-mass-ratio limit, $\\mu/M=\

  1. Fishes of water bodies within the Ukrainian part of the Chernobyl exclusion zone: current levels of radioactive contamination and absorbed dose rate

    International Nuclear Information System (INIS)

    The results of studies of radioactive contamination of ichthyofauna of water bodies of the Chernobyl exclusion zone (ChEZ) during 2012-2013 are presented. The fish sampled from water bodies with different hydrological mode was used: (1) stagnant lakes (Vershyna, Glyboke, Azbuchyn, Daleke); (2) reservoir with slow water exchange (cooling pond of the Chernobyl NPP); (3) conditionally stagnant water bodies (separated from the main riverbed of the Pripyat River - Yanovsky and Novoshepelichesky Crawls and part of the Krasnensky former river bed); (4) semi-flowing water body (Krasnensky former river bed located outside of the dammed territory); (5) open crawls of the Pripyat river ('Schepochka' and Chernobylsky) and (6) waterway (riverbed sites of the Pripyat River). The highest levels of radionuclide concentrations were determined in fish of the stagnant water objects - 937-25907 Bq/kg (w.w.) of 137Cs and 1845-101220 Bq/kg of 90Sr. In fish of cooling pond the concentration of 137Cs registered in range 750-4200 and 90Sr - 41-512 Bq/kg. In ichthyofauna of water bodies which concern to the third group, specific activity of 137Cs and 90Sr fluctuated accordingly within range of 520-3385 and 722-6210, and in a semi-flowing reservoir - 573-2948 and 97-4484 Bq/kg. The concentrations of 137Cs in fish of the fifth and sixth groups were accordingly 25-159 and 11-224 as well as 90Sr - 36-174 and 3-14 Bq/kg. The ratio of specific activity of 90Sr/137Cs for pray fish from all studied groups of water bodies, except the second and the sixth ones, was in range 1.5-39.7. Thus intensity of water exchange is one of the defining factors, influencing on level of radionuclide specific activity in fish, especially 90Sr - the higher the flow age, the lower the level of radioactive contamination of fish inhabiting it. Calculation of the absorbed dose rate has shown that highest radiation dose was in fish inhabiting lake ecosystems where it makes for different species from 2.8 (pelagic fish) to

  2. Fishes of water bodies within the Ukrainian part of the Chernobyl exclusion zone: current levels of radioactive contamination and absorbed dose rate

    Energy Technology Data Exchange (ETDEWEB)

    Kaglyan, Alexander Ye.; Gudkov, Dmitri I. [Institute of Hydrobiology of the NAS of Ukraine, Geroyiv Stalingrada Ave. 12, UA- 04210, Kyiv (Ukraine)

    2014-07-01

    The results of studies of radioactive contamination of ichthyofauna of water bodies of the Chernobyl exclusion zone (ChEZ) during 2012-2013 are presented. The fish sampled from water bodies with different hydrological mode was used: (1) stagnant lakes (Vershyna, Glyboke, Azbuchyn, Daleke); (2) reservoir with slow water exchange (cooling pond of the Chernobyl NPP); (3) conditionally stagnant water bodies (separated from the main riverbed of the Pripyat River - Yanovsky and Novoshepelichesky Crawls and part of the Krasnensky former river bed); (4) semi-flowing water body (Krasnensky former river bed located outside of the dammed territory); (5) open crawls of the Pripyat river ('Schepochka' and Chernobylsky) and (6) waterway (riverbed sites of the Pripyat River). The highest levels of radionuclide concentrations were determined in fish of the stagnant water objects - 937-25907 Bq/kg (w.w.) of {sup 137}Cs and 1845-101220 Bq/kg of {sup 90}Sr. In fish of cooling pond the concentration of {sup 137}Cs registered in range 750-4200 and {sup 90}Sr - 41-512 Bq/kg. In ichthyofauna of water bodies which concern to the third group, specific activity of {sup 137}Cs and {sup 90}Sr fluctuated accordingly within range of 520-3385 and 722-6210, and in a semi-flowing reservoir - 573-2948 and 97-4484 Bq/kg. The concentrations of {sup 137}Cs in fish of the fifth and sixth groups were accordingly 25-159 and 11-224 as well as {sup 90}Sr - 36-174 and 3-14 Bq/kg. The ratio of specific activity of {sup 90}Sr/{sup 137}Cs for pray fish from all studied groups of water bodies, except the second and the sixth ones, was in range 1.5-39.7. Thus intensity of water exchange is one of the defining factors, influencing on level of radionuclide specific activity in fish, especially {sup 90}Sr - the higher the flow age, the lower the level of radioactive contamination of fish inhabiting it. Calculation of the absorbed dose rate has shown that highest radiation dose was in fish inhabiting lake

  3. Large-area surveys for black carbon and other light-absorbing impurities in snow: Arctic, Antarctic, North America, China (Invited)

    Science.gov (United States)

    Warren, S. G.; Doherty, S. J.; Hegg, D.; Dang, C.; Zhang, R.; Grenfell, T. C.; Brandt, R. E.; Clarke, A. D.; Zatko, M.

    2013-12-01

    Absorption of radiation by ice is extremely weak at visible and near-UV wavelengths, so small amounts of light-absorbing impurities (LAI) in snow can dominate the absorption of sunlight at these wavelengths, reducing the albedo relative to that of pure snow and leading to earlier snowmelt. Snow samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean, on tundra, glaciers, ice caps, sea ice, and frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack was accessible for sampling. Snow was also collected at 67 sites in western North America. Expeditions from Lanzhou University obtained black carbon (BC) amounts at 84 sites in northeast and northwest China. BC was measured at 3 locations on the Antarctic Plateau, and at 5 sites on East Antarctic sea ice. The snow is melted and filtered; the filters are analyzed in a spectrophotometer. Median BC mixing ratios in snow range over 4 orders of magnitude from 0.2 ng/g in Antarctica to 1000 ng/g in northeast China. Chemical analyses, input to a receptor model, indicate that the major source of BC in most of the Arctic is biomass burning, but industrial sources dominate in Svalbard and the central Arctic Ocean. Non-BC impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. In northeast China BC is the dominant LAI, but in Inner Mongolia soil dominates. When the snow surface layer melts, much of the BC is left at the top of the snowpack rather than carried away in meltwater, thus causing a positive feedback on snowmelt. This process was quantified through field studies in Greenland, Alaska, and Norway, where we found that only 10-30% of the BC is removed with meltwater. The BC content of the Arctic atmosphere has declined markedly since 1989, according to the continuous measurements of near-surface air in Canada, Alaska, and Svalbard. Correspondingly, our recent BC

  4. The 3D plant canopy radiative transfer analysis in an Alaskan black spruce forest: the characteristics of fraction of absorbed photosynthetically active radiation in the heterogeneous landscape

    Science.gov (United States)

    Kobayashi, H.; Suzuki, R.; Nagai, S.; Nakai, T.; Kim, Y.

    2012-12-01

    Over the last couple of decades, the three dimensional plant canopy radiative transfer models have been developed, improved and used for the retrievals of biophysical variables of vegetative surface. Fraction of absorbed photosynthetically active radiation (FAPAR) by plant canopy, a similar variable to heating rate in the atmosphere, is one of the important biophysical variables to infer the terrestrial plant canopy photosynthesis. FAPAR can be estimated by the radiative transfer model inversion or the empirical relationships between FAPAR and vegetation indices such as normalized difference vegetation index (NDVI). To date, some global FAPAR products are publicly available. These products are estimated from the moderate resolution satellites such as MODIS and SPOT-VEGETATION. One may apply the similar FAPAR algorithms to higher spatial resolution satellites if the ecosystem structures are horizontally homogeneous, which means that the adjacent satellite pixels have a similar spectral properties. If the vegetation surface is highly heterogeneous, "domain average FAPAR", which assumes no net horizontal radiation fluxes, can be unrealistically high (more than 1). In this presentation, we analyzed the characteristics of FAPAR in a heterogeneous landscape. As a case study, we selected our study site in a sparse black spruce forest in Alaska. We conducted the field campaigns to measure forest structural and optical properties that are used in the radiative transfer simulation. We used a 3D radiative transfer, FLiES (Kobayashi, H. and H. Iwabuchi (2008), A coupled 1-D atmosphere and 3-D canopy radiative transfer model for canopy reflectance, light environment, and photosynthesis simulation in a heterogeneous landscape, Remote Sensing of Environment, 112, 173-185) to create a high resolution simulated spectral reflectance and FAPAR images over the course of the growing season. From the analysis, we show (1) FAPAR with no net horizontal fluxes assumption can be higher than

  5. Black-body radiation shift of atomic energy-levels:The $ (Z \\alpha)^2\\alpha T^2/m $ correction

    OpenAIRE

    Zhou, Wanping; Mei, Xuesong; Lu, Jingjun; Qiao, Haoxue

    2016-01-01

    The next-to-leading order black-body radiation(BBR) shift to atomic energy-levels, namely $ (Z\\alpha)^2\\alpha T^2/m $ correction, was studied by using the nonrelativistic quantum electrodynamics(NRQED). We also estimate the one-loop contribution of quadrupole and the two-loop contributions of BBR-shift of the thermal(real) photon. These corrections have not been investigated before. The order of magnitude BBR-shift indicates the one-loop contribution of quadrupole is stronger than the previou...

  6. Role of the multipolar black-body radiation shifts in the atomic clocks at the 10-18 uncertainty level

    Indian Academy of Sciences (India)

    B K Sahoo

    2014-08-01

    We present here an overview of the role of the multipolar black-body radiation (BBR) shifts in the single ion atomic clocks to appraise the anticipated 10-18 uncertainty level. With an attempt to use the advanced technologies for reducing the instrumental uncertainties at the unprecedented low, it is essential to investigate contributions from the higher-order systematics to achieve the ambitious goal of securing the most precise clock frequency standard. In this context, we have analysed contributions to the BBR shifts from the multipolar polarizabilities in a few ion clocks.

  7. Onset of optical-phonon cooling in multilayer graphene revealed by RF noise and black-body radiation thermometries

    International Nuclear Information System (INIS)

    We report on electron cooling power measurements in few-layer graphene excited by Joule heating by means of a new setup combining electrical and optical probes of the electron and phonon baths temperatures. At low bias, noise thermometry allows us to retrieve the well known acoustic phonon cooling regimes below and above the Bloch-Grüneisen temperature, with additional control over the phonon bath temperature. At high electrical bias, we show the relevance of direct optical investigation of the electronic temperature by means of black-body radiation measurements. In this regime, the onset of new efficient relaxation pathways involving optical modes is observed. (paper)

  8. Effect of different absorbing materials on the performance of basin solar still under Libyan climate conditions

    International Nuclear Information System (INIS)

    This experimental study deals with a single-basin solar still using various absorbing materials with and without black painting. Different types of absorbing materials with and without black painting were used to enhance the solar still productivity through improvement in absorptivity. These materials are steel and aluminum with and without black painting and rubber. Two identical solar stills were manufactured using locally available materials. All the results were compared together to reach the best absorbing materials with and without painting that can be used for solar still. it was found that the rubber absorber has the highest water collection during daytime, followed by the black painted steel absorber, then by black painted aluminum absorber and steel without painting absorber. The average enhancement in the daily productivity was about 50% for the rubber absorber compared with the black painted aluminum absorber and about 43% for the rubber absorber compared with the black painted steel absorber.(author)

  9. The metabolic syndrome in black hypertensive women - Waist circumference more strongly related than body mass index

    NARCIS (Netherlands)

    Rheeder, P; Stolk, RP; Veenhouwer, JF; Grobbee, DE

    2002-01-01

    Objective. To examine the association between measures of. obesity and features of the metabolic syndrome in treated. black female hypertensive subjects. Design. Cross-sectional study. Setting. An urban primary health care centre in Mamelodi, Pretoria. Subjects. Women with hypertension and without k

  10. Toward faithful templates for non-spinning binary black holes using the effective-one-body approach

    CERN Document Server

    Buonanno, Alessandra; Baker, John G; Centrella, Joan; Kelly, Bernard J; McWilliams, Sean T; van Meter, James R

    2007-01-01

    We present an accurate approximation of the full gravitational radiation waveforms generated in the merger of non-eccentric systems of two non-spinning black holes. Utilizing information from recent numerical relativity simulations and the natural flexibility of the effective-one-body (EOB) model, we extend the latter so that it can successfully match the numerical relativity waveforms during the last stages of inspiral, merger and ringdown. By ``successfully'' here, we mean with phase differences < 8% of a gravitational-wave cycle accumulated by the end of the ringdown phase, maximizing only over time of arrival and initial phase. We obtain this result by simply adding a 4-post-Newtonian order correction in the EOB radial potential and determining the (constant) coefficient by imposing high-matching performances with numerical waveforms of mass ratios m1/m2 = 1, 3/2, 2 and 4, m1 and m2 being the individual black-hole masses. The final black-hole mass and spin predicted by the numerical simulations are use...

  11. Taking into account absorbed doses in tooth enamel due to internal irradiation of human body by radioactive cesium isotopes at analysis EPR dosimetry data: Calculation by Monte-Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Borysheva, N. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation); Ivannikov, A. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation)], E-mail: Ivannikov-Alexander@yandex.ru; Tikunov, D.; Orlenko, S.; Skvortsov, V.; Stepanenko, V. [Medical Radiological Research Center, Korolyov str., 4, Obninsk 249020 (Russian Federation); Hoshi, M. [Research Institute for Radiation Biology and Medicine, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553 (Japan)

    2007-07-15

    By Monte-Carlo simulation of ionizing particles transport, for a realistic mathematical phantom of a man supplemented by a dental region, absorbed doses in teeth enamel and whole body doses are calculated for cases of internal irradiation by {sup 137}Cs and {sup 134}Cs isotopes incorporated in the human body resulted from staying in radioactive contaminated territory. It is shown that dose in enamel constitutes (40{+-}4)% and (59{+-}6)% of whole body dose resulted from the decay of {sup 137}Cs and {sup 134}Cs isotopes, respectively. The results of calculations may be used for conversion of absorbed dose in enamel obtained by the tooth enamel EPR spectroscopy method to whole body dose for dosimetric investigation of population of territories contaminated by the radioactive cesium, which is specific for the Chernobyl accident.

  12. Mass dynamics of wintering Pacific Black Brant: Body, adipose tissue, organ, and muscle masses vary with location

    Science.gov (United States)

    Mason, D.D.; Barboza, P.S.; Ward, D.H.

    2007-01-01

    We compared body size and mass of the whole body, organs, adipose tissue, and muscles of adult Pacific Black Brant (Branta bernicla nigricans (Lawrence, 1846)) collected concurrently in Alaska and Baja California during the fall, winter, and spring of 2002-2003. Head and tarsal lengths of males were similar between sites and slightly larger for females in Alaska than in Baja California. Brant appear to operate under similar physiological bounds, but patterns of nutrient allocation differ between sites. Birds wintering in Alaska lost similar amounts of adipose tissue during early winter as birds in Baja California gained during late winter before migration. Masses of the body, adipose tissue, and flight muscles during mid-winter were similar between sites. Seasonal adipose tissue deposition may, therefore, equally favor winter residency or long-distance migration. Gonad and liver masses increased in late winter for birds in Alaska but not for those in Baja California, suggesting birds wintering in Baja may delay reproductive development in favor of allocating reserves needed for migration. Phenotypic flexibility allows Brant to use widely divergent wintering sites. The wintering location of Brant likely depends more upon changes in environmental conditions and food availability, than upon physiological differences between the two wintering populations. ?? 2007 NRC.

  13. Infrared heterodyne spectroscopy of astronomical and laboratory sources at 8.5 micron. [absorption line profiles of nitrogen oxide and black body emission from Moon and Mars

    Science.gov (United States)

    Mumma, M.; Kostiuk, T.; Cohen, S.; Buhl, D.; Vonthuna, P. C.

    1974-01-01

    The first infrared heterodyne spectrometer using tuneable semiconductor (PbSe) diode lasers has been constructed and was used near 8.5 micron to measure absorption line profiles of N2O in the laboratory and black body emission from the Moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz and the minimum detectable (black body) power was 1 x 10 to the minus 16th power watts for 8 minutes of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.

  14. Usb Spectrometers and the Temperature of the Sun: Measuring Black Body Radiation in the Palm of your Hand

    Science.gov (United States)

    Zaleski, Daniel P.; Horrocks, Benjamin R.; Walker, Nick

    2015-06-01

    A new experiment appropriate for both general chemistry and physical chemistry students will be described. The experiment utilizes "pocket size" USB spectrometers (operating in the UV/vis region) coupled with fiber optic cables to record a solar spectrum. A further extension of the experiment involves recording spectra of a light bulb at several voltages (and thus resistances). Using provided software, students can fit black body distributions to their obtained spectra. The software will display the acquired spectrum, a simulation based on their guess temperature, a simulation based on their fit, and OMC2 for both. Students can then compare their results to the known temperature of the sun and the known temperature vs resistance curve of tungsten.

  15. Television viewing is not predictive of Body Mass Index in Black and Hispanic young adult females

    OpenAIRE

    Richmond, Tracy K.; Walls, Courtney; Holly C. Gooding; Field, Alison E.

    2009-01-01

    Previous studies have observed that television viewing is predictive of obesity and weight gain. We examined whether the cross-sectional association between television viewing and body mass index (BMI) varied by racial/ethnic subgroups among young women in Wave III (collected in 2001–2002) of the National Longitudinal Study of Adolescent Health. We used multivariate linear regression to examine the relationship between TV viewing and BMI among 6,049 females while controlling for socio-demogra...

  16. 'Kludge' gravitational waveforms for a test-body orbiting a Kerr black hole

    International Nuclear Information System (INIS)

    One of the most exciting potential sources of gravitational waves for low-frequency, space-based gravitational wave (GW) detectors such as the proposed Laser Interferometer Space Antenna (LISA) is the inspiral of compact objects into massive black holes in the centers of galaxies. The detection of waves from such 'extreme mass ratio inspiral' systems (EMRIs) and extraction of information from those waves require template waveforms. The systems' extreme mass ratio means that their waveforms can be determined accurately using black hole perturbation theory. Such calculations are computationally very expensive. There is a pressing need for families of approximate waveforms that may be generated cheaply and quickly but which still capture the main features of true waveforms. In this paper, we introduce a family of such kludge waveforms and describe ways to generate them. Different kinds of kludges have already been used to scope out data analysis issues for LISA. The models we study here are based on computing a particle's inspiral trajectory in Boyer-Lindquist coordinates, and subsequent identification of these coordinates with flat-space spherical polar coordinates. A gravitational waveform may then be computed from the multipole moments of the trajectory in these coordinates, using well-known solutions of the linearised gravitational perturbation equations in flat space time. We compute waveforms using a standard slow-motion quadrupole formula, a quadrupole/octupole formula, and a fast-motion, weak-field formula originally developed by Press. We assess these approximations by comparing to accurate waveforms obtained by solving the Teukolsky equation in the adiabatic limit (neglecting GW backreaction). We find that the kludge waveforms do extremely well at approximating the true gravitational waveform, having overlaps with the Teukolsky waveforms of 95% or higher over most of the parameter space for which comparisons can currently be made. Indeed, we find these

  17. Effects of zilpaterol hydrochloride on internal body temperature and respiration rate of black-hided feedlot steers and heifers during moderate heat stress

    Science.gov (United States)

    The objective of this study was to examine the effects of zilpaterol hydrochloride (ZH) on the internal body temperature and respiration rate of feedlot cattle during moderate heat stress. Black-hided steers and heifers (n=96) were sourced from a commercial feedlot and transported to the Texas Tech...

  18. Distribution of Bacteria Injected in Body of Giant Black Shrimp, Penaeus Monodon

    Institute of Scientific and Technical Information of China (English)

    GUO Zhixun(郭志勋); Karin van de Braak; Magriet Botterbloom

    2004-01-01

    Distribution of injected Vibrio anguillarum in body of Penaeus monodon was studied with immunohistochemical method. Bacteria could be detected throughout the experiment in some individuals; however in lymphoid tissue, gill, heart and haemolymph of all vibrio injected shrimp, the bacteria could be observed only 5 min after injection. The bacteria density in haemolymph, haemolymph of the hepatopancreas and gills decreased with time. In the lymphoid organ and heart, the bacteria density was the highest 48 h after injection, then decreased. Nodules could be formed in the heart, lymphoid organ and injection site.

  19. Investigating the retention of intermediate-mass black holes in star clusters using N-body simulations

    Science.gov (United States)

    Konstantinidis, Symeon; Amaro-Seoane, Pau; Kokkotas, Kostas D.

    2013-09-01

    Context. Unlike supermassive and stellar-mass black holes (SBHs), the existence of intermediate-mass black holes (IMBHs) with masses ranging between 102-5 M⊙ has not yet been confirmed. The main problem in the detection is that the innermost stellar kinematics of globular clusters (GCs) or small galaxies, the possible natural loci to IMBHs, are very difficult to resolve. However, if IMBHs reside in the centre of GCs, a possibility is that they interact dynamically with their environment. A binary formed with the IMBH and a compact object of the GC would naturally lead to a prominent source of gravitational radiation, detectable with future observatories. Aims: We use N-body simulations to study the evolution of GCs containing an IMBH and calculate the gravitational radiation emitted from dynamically formed IMBH-SBH binaries and the possibility that the IMBH escapes the GC after an IMBH-SBH merger. Methods: We ran for the first time direct-summation integrations of GCs with an IMBH including the dynamical evolution of the IMBH with the stellar system and relativistic effects, such as energy loss in gravitational waves (GWs) and periapsis shift, and gravitational recoil. Results: We find in one of our models an intermediate mass-ratio inspiral (IMRI), which leads to a merger with a recoiling velocity higher than the escape velocity of the GC. The GWs emitted fall in the range of frequencies that a LISA-like observatory could detect, like the European eLISA or with mission options considered in the recent preliminary mission study conducted in China. The merger has an impact on the global dynamics of the cluster, as an important heating source is removed when the merged system leaves the GC. The detection of one IMRI would constitute a test of GR, as well as an irrefutable proof of the existence of IMBHs.

  20. The accretion disk and ionized absorber of the 9.7 hr dipping black hole binary MAXI J1305–704

    International Nuclear Information System (INIS)

    We report the results from X-ray studies of the newly discovered black hole candidate MAXI J1305–704 based on Suzaku and Swift observations in the low/hard and high/soft states, respectively. The long Suzaku observation shows two types of clear absorption dips, both of which recur on a dip interval of 9.74 ± 0.04 hr, which we identify with the orbital period. There is also partially ionized absorption in the nondip (persistent) emission in both the high/soft state and, very unusually, the low/hard state. However, this absorption (in both states) has substantially lower ionization than that seen in other high inclination systems, where the material forms a homogeneous disk wind. Here instead the absorption is most likely associated with clumpy, compact structures associated with the dipping material, which we see uniquely in this source likely because we view it at a very large inclination angle. A large inclination angle is also favored, together with a low black hole mass, to explain the high disk temperature seen in the fairly low luminosity high/soft state, as Doppler boosting enhances the disk temperature at high inclination. The disk radius inferred from these data is significantly smaller than that of the soft component seen in the low/hard state, supporting models where the disk is truncated at low luminosities. We find, however, that the lack of variability power on timescales of ∼50 s in the Suzaku low/hard state data is difficult to explain, even with a low-mass black hole.

  1. Thermal Characterization of Absorbing Coatings for Thermal Detectors of Radiation by Photopyroelectric Method

    OpenAIRE

    Bravina, Svetlana L.; Morozovsky, Nicholas V.; Dovbeshko, Galina I.; Obraztsova, Elena D.

    2006-01-01

    By photothermomodulatoin method the comparative study of thermal diffusivity of absorbing coating for sensitive elements of pyroelectric detectors of radiation formed from metal dispersion layer blacks, dielectric paint blacks and carbon nanotubes paint blacks has been performed. Prospects of using carbon nanotubes based black absorbing coatings for pyroelectric and other thermal detector application are shown.

  2. Black tea

    Science.gov (United States)

    ... 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 ...

  3. Black body models for liquid zirconium and thermophysical properties up to 4100 K (density, resistivity, specific heat capacity, emissivity)

    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)

  4. Black-body radiation shift of atomic energy-levels:The $ (Z \\alpha)^2\\alpha T^2/m $ correction

    CERN Document Server

    Zhou, Wanping; Lu, Jingjun; Qiao, Haoxue

    2016-01-01

    The next-to-leading order black-body radiation(BBR) shift to atomic energy-levels, namely $ (Z\\alpha)^2\\alpha T^2/m $ correction, was studied by using the nonrelativistic quantum electrodynamics(NRQED) at first. This $T^{2}$-dependent correction has not been investigated before, and only contains the contribution of eletric-dipole of thermal photon. In order to study the contribution of multipolar. We estimate the two-loop contributions of BBR-shift by using quantum electrodynamics approach(QED), and find both one-loop and two-loop diagram contribute to the $ (Z\\alpha)^2\\alpha T^2/m $ correction. Integrating the results which are obtained by these two approaches, the $ (Z\\alpha)^2\\alpha T^2/m $ correction we derived is in principle applicable to multi-electron atoms and contains the contribution of multipolar. The order of magnitude BBR-shift indicates this next-to-leading order BBR-shift may be as significant as the leading order in the multi-electron atoms or cold ones.

  5. Boosted Tidal Disruption by Massive Black Hole Binaries During Galaxy Mergers - In The View of N-Body Simulation

    CERN Document Server

    Li, Shuo; Berczik, Peter; Spurzem, Rainer

    2015-01-01

    Supermassive black hole binaries (SMBHBs) are productions of the hierarchical galaxy formation model. There are many close connections between central SMBH and its host galaxy because the former plays very important roles on the formation and evolution of a galaxy. For this reason, the evolution of SMBHBs in merging galaxies is an essential problem. Since there are many discussions about SMBHB evolution in gas rich environment, we focus on the quiescent galaxy, using tidal disruption as a diagnostic tool. Our study is based on a series of numerical large particle number direct N-body simulations for dry major mergers. According to the simulation results, the evolution can be divided into three phases. In phase I, the tidal disruption rate for two well separated SMBHs in merging system has similar level to single SMBH in isolate galaxy. After two SMBHs getting close enough to form a bound binary in phase II, the disruption rate can be enhanced for ~ 2 order of magnitudes within a short time. This "boosted" dis...

  6. A possible cosmological application of some thermodynamic properties of the black body radiation in $n-$dimensional Euclidean spaces

    CERN Document Server

    Gonzalez-Ayala, Julian; Cordero, Rubén; Angulo-Brown, F

    2015-01-01

    In this work we present the generalization of some thermodynamic properties of the black body radiation (BBR) towards an $n-$dimensional Euclidean space. For this case the Planck function and the Stefan-Boltzmann law have already been given by Landsberg and de Vos and some adjustments by Menon and Agrawal. However, since then no much more has been done on this subject and we believe there are some relevant aspects yet to explore. In addition to the results previously found we calculate the thermodynamic potentials, the efficiency of the Carnot engine, the law for adiabatic processes and the heat capacity at constant volume. There is a region at which an interesting behavior of the thermodynamic potentials arise, maxima and minima appear for the $n-d$ BBR system at very high temperatures and low dimensionality, suggesting a possible application to cosmology. Finally we propose that an optimality criterion in a thermodynamic framework could have to do with the $3-d$ nature of the universe.

  7. Body size across the life course and risk of premenopausal and postmenopausal breast cancer in Black women, the Carolina Breast Cancer Study, 1993–2001

    Science.gov (United States)

    Robinson, Whitney R.; Tse, Chiu Kit; Olshan, Andrew F.; Troester, Melissa A.

    2014-01-01

    It is believed that greater adiposity is associated with reduced risk of breast cancer in premenopausal but increased risk in postmenopausal women. However, few studies have evaluated these relationships among Black women or examined anthropometric measures other than near-diagnosis body mass index (BMI). PURPOSE This study investigated associations between measures of body size across the life course and breast cancer risk among Black and White women living in the U.S. South. METHODS We used data from the Carolina Breast Cancer Study, a population-based case-control study of invasive breast cancer in North Carolina women aged 20–74 years. We assessed nine body size variables, including age 10 relative weight; age 18 BMI; adult weight gain; “reference” BMI 1 year before interview; and post-diagnosis measured BMI and abdominal obesity measures. RESULTS Among premenopausal Whites, heavier childhood relative weight was associated with decreased cancer risk (odds ratio [OR]=0.48 [95% confidence interval (CI)=0.33–0.70]). Among premenopausal Blacks, greater adult waist circumference and waist-to-hip ratio (WHR) were associated with increased risk (waist OR=1.40 [1.00–1.97] and high tertile WHR OR=2.03 [1.29–3.19]), with associations for WHR in a similar direction in Whites. Among postmenopausal women, recalled body size was not associated with risk, except for increased risk associated with adult weight gain among White non-hormone therapy users. ER/PR status and hormone therapy use also modified other associations. DISCUSSION In this population, greater adult BMI was not associated with increased breast cancer risk, but some measures of early-life body size and abdominal obesity were associated with risk. PMID:24924530

  8. Measurement of absorbed radiation doses during whole body irradiation for bone marrow transplants using thermoluminescent dosimeters; Verificacao das doses de radiacao absorvidas durante a tecnica de irradiacao de corpo inteiro nos transplantes de medula ossea, por meio de dosimetros termoluminescentes

    Energy Technology Data Exchange (ETDEWEB)

    Giordani, Adelmo Jose; Segreto, Helena Cristina Comodo; Segreto, Roberto Araujo; Medeiros, Regina Bitelli; Oliveira, Jose Salvador R. de [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Setor de Radioterapia]. E-mail: adelmogiordani@ig.com.br

    2004-10-01

    The objective was to evaluate the precision of the absorbed radiation doses in bone marrow transplant therapy during whole body irradiation. Two-hundred CaSO{sub 4}:Dy + teflon tablets were calibrated in air and in 'phantom'. These tablets were randomly selected and divided in groups of five in the patients' body. The dosimetric readings were obtained using a Harshaw 4000A reader. Nine patients had their entire bodies irradiated in parallel and opposite laterals in a cobalt-60 Alcion II model, with a dose rate of 0.80 Gy/min at 80.5 cm, {l_brace}(10 ? 10) cm{sup 2} field. The dosimetry of this unit was performed using a Victoreen 500 dosimeter. For the determination of the mean dose at each point evaluated, the individual values of the tablets calibrated in air or 'phantom' were used, resulting in a build up of 2 mm to superficialize the dose at a distance of 300 cm. In 70% of the patients a variation of less than 5% in the dose was obtained. In 30% of the patients this variation was less than 10%, when values obtained were compared to the values calculated at each point. A mean absorption of 14% was seen in the head, and an increase of 2% of the administered dose was seen in the lungs. In patients with latero-lateral distance greater than 35 cm the variation between the calculated doses and the measured doses reached 30% of the desired dose, without the use of compensation filters. The measured values of the absorbed doses at the various anatomic points compared to the desired doses (theoretic) presented a tolerance of {+-} 10%, considering the existent anatomical differences and when using the individual calibration factors of the tablets. (author)

  9. Black Hole Battery

    Science.gov (United States)

    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.

  10. The static and dynamic polarisability, and the Stark and black-body radiation frequency shifts of the molecular hydrogen ions H2+, HD+, and D2+

    CERN Document Server

    Schiller, Stephan; Bekbaev, Ashat K; Korobov, Vladimir I

    2014-01-01

    We calculate the DC Stark effect for three molecular hydrogen ions in the non-relativistic approximation. The effect is calculated both in dependence on the rovibrational state and in dependence on the hyperfine state. We discuss special cases and approximations. We also calculate the AC polarisabilities for several rovibrational levels, and therefrom evaluate accurately the black-body radiation shift, including the effects of excited electronic states. The results enable the detailed evaluation of certain systematic shifts of the transitions frequencies for the purpose of ultra-high-precision optical, microwave or radio-frequency spectroscopy in ion traps.

  11. Formation of a diamond-like carbon film by magnetron sputtering of a graphite target under radiation flux from a black-body model

    Science.gov (United States)

    Kostanovskiy, A. V.; Pronkin, A. A.; Kostanovskiy, I. A.

    2014-04-01

    A method of depositing a film (under a radiation flux from a high-temperature black-body model) by magnetron sputtering of a graphite target has been implemented. The elemental composition and structure of deposited films have been analyzed by X-ray photoelectron spectroscopy and characteristic electron-energy-loss spectroscopy. The investigations have shown that chemically pure diamond-like films can be formed at a radiation-flux density no less than 1.5 × 10-4 W/m2 in the spectral range of 170-255 nm.

  12. The effect of the male-female body-size difference on absorbed dose-rate distributions in humans from natural gamma rays

    International Nuclear Information System (INIS)

    Previous calculations of the natural gamma dose to human organs and tissues were based on the MIRD phantom, a 70 kg hermaphrodite model representing both sexes. This phantom was scaled down to 58 kg, the weight of the ICRP reference female. The effective dose to the reference male and female, based on the unaltered phantom and the scaled phantom respectively, were calculated and averaged to give revised doses to the U.S. population. The dose to females tends to be higher than to males. The over-all effect is about 10%. For most tissues the use of the hermaphrodite model results in a 5% underestimate in population dose values. Hence the correction for the male-female body size difference is to add 1-2 mrad/yr to the estimate of the gamma-ray dose rate to the U.S. population. On this basis, the average annual natural gamma-ray doses to the population are 33 +- 0.1 mrad/yr to the active marrow. The respective body-shielding factors are 0.598 +- 0.009 and 0.608 +- 0.0002 rad/R. (author)

  13. Darker than black: radiation-absorbing metamaterial

    CERN Document Server

    Narimanov, E E; Barnakov, Yu A; Tumkur, T U; Noginov, M A

    2011-01-01

    We show that corrugated surfaces of hyperbolic metamaterials scatter light preferentially inside the media, resulting in a very low reflectance and ultimate dark appearance in the spectral range of hyperbolic dispersion. This phenomenon of fundamental importance, demonstrated experimentally in arrays of silver nanowires grown in alumina membranes, originates from a broad-band singularity in the density of photonic states. It paves the road to a variety of applications ranging from the stealth technology to high-efficiency solar cells and photodetectors.

  14. Dynamical evolution of massive black holes in galactic-scale N-body simulations - introducing the regularized tree code "rVINE"

    CERN Document Server

    Karl, S J; Naab, T; Haehnelt, M G; Spurzem, R

    2015-01-01

    We present a hybrid code combining the OpenMP-parallel tree code VINE with an algorithmic chain regularization scheme. The new code, called "rVINE", aims to significantly improve the accuracy of close encounters of massive bodies with supermassive black holes in galaxy-scale numerical simulations. We demonstrate the capabilities of the code by studying two test problems, the sinking of a single massive black hole to the centre of a gas-free galaxy due to dynamical friction and the hardening of a supermassive black hole binary due to close stellar encounters. We show that results obtained with rVINE compare well with NBODY7 for problems with particle numbers that can be simulated with NBODY7. In particular, in both NBODY7 and rVINE we find a clear N-dependence of the binary hardening rate, a low binary eccentricity and moderate eccentricity evolution, as well as the conversion of the galaxy's inner density profile from a cusp to a a core via the ejection of stars at high velocity. The much larger number of par...

  15. Effective one-body Hamiltonian of two spinning black holes with next-to-next-to-leading order spin-orbit coupling

    International Nuclear Information System (INIS)

    Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian spin-orbit Hamiltonian for spinning binaries [J. Hartung and J. Steinhoff, arXiv:1104.3079.] we improve the effective-one-body description of the dynamics of two spinning black holes by including NNLO effects in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order spin-orbit Hamiltonian computed in [T. Damour, P. Jaranowski, and G. Schaefer, Phys. Rev. D 78, 024009 (2008).]. The present effective-one-body Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the next-to-leading order spin-orbit coupling.

  16. Confirming and improving post-Newtonian and effective-one-body results from self-force computations along eccentric orbits around a Schwarzschild black hole

    Science.gov (United States)

    Bini, Donato; Damour, Thibault; Geralico, Andrea

    2016-03-01

    We analytically compute, through the six-and-a-half post-Newtonian order, the second-order-in-eccentricity piece of the Detweiler-Barack-Sago gauge-invariant redshift function for a small mass in eccentric orbit around a Schwarzschild black hole. Using the first law of mechanics for eccentric orbits [A. Le Tiec, First law of mechanics for compact binaries on eccentric orbits, Phys. Rev. D 92, 084021 (2015).] we transcribe our result into a correspondingly accurate knowledge of the second radial potential of the effective-one-body formalism [A. Buonanno and T. Damour, Effective one-body approach to general relativistic two-body dynamics, Phys. Rev. D 59, 084006 (1999).]. We compare our newly acquired analytical information to several different numerical self-force data and find good agreement, within estimated error bars. We also obtain, for the first time, independent analytical checks of the recently derived, comparable-mass fourth-post-Newtonian order dynamics [T. Damour, P. Jaranowski, and G. Schaefer, Nonlocal-in-time action for the fourth post-Newtonian conservative dynamics of two-body systems, Phys. Rev. D 89, 064058 (2014).].

  17. Acoustic coherent perfect absorbers

    International Nuclear Information System (INIS)

    In this paper, we explore the possibility of achieving acoustic coherent perfect absorbers. Through numerical simulations in two dimensions, we demonstrate that the energy of coherent acoustic waves can be totally absorbed by a fluid absorber with specific complex mass density or bulk modulus. The robustness of such absorbing systems is investigated under small perturbations of the absorber parameters. We find that when the resonance order is the lowest and the size of the absorber is comparable to the wavelength in the background, the phenomenon of perfect absorption is most stable. When the wavelength inside both the background and the absorber is much larger than the size of the absorber, perfect absorption is possible when the mass density of the absorber approaches the negative value of the background mass density. Finally, we show that by using suitable dispersive acoustic metamaterials, broadband acoustic perfect absorption may be achieved. (papers)

  18. On the commodification of the black female body: the critical implications of the alienability of fetal tissue.

    Science.gov (United States)

    Bridges, Khiara M

    2002-01-01

    Recent scientific experimentation has revealed that fetal tissue yielded from abortions has remarkable therapeutic value. This Note posits that the demand for fetal tissue likely will expand to the point where the current supply no longer satisfies it. Therefore, in order to obtain tissue from women who would not otherwise donate their abortuses, should research organizations, pharmaceutical companies, and doctors be allowed to offer women a "financial incentive" for their fetal tissue? That is, should women be allowed to sell their fetal tissue? This Note explores the question from a Critical Race Theory perspective. It analyzes the impact that a market in fetal tissue will have on Black women, who are more likely to participate in such a market due to their precarious economic situation, their higher abortion rate, and the effects of internalized oppression. The Note concludes that because Black women will be disproportionately exploited, as well as disenfranchised from the benefits produced by a market in fetal tissue, fetal tissue should not be made market alienable. PMID:11973807

  19. The ALICE absorbers

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    Weighing more than 400 tonnes, the ALICE absorbers and the surrounding support structures have been installed and aligned with a precision of 1-2 mm, hardly an easy task but a very important one. The ALICE absorbers are made of three parts: the front absorber, a 35-tonne cone-shaped structure, and two small-angle absorbers, long straight cylinder sections weighing 18 and 40 tonnes. The three pieces lined up have a total length of about 17 m.

  20. Black tea polyphenols and polysaccharides improve body composition, increase fecal fatty acid, and regulate fat metabolism in high-fat diet-induced obese rats.

    Science.gov (United States)

    Wu, Tao; Guo, Yu; Liu, Rui; Wang, Kuan; Zhang, Min

    2016-05-18

    With the current changes in diet and living habits, obesity has become a global health problem. Thus, the weight-reducing function of tea has attracted considerable attention. This study investigated the anti-obesity effect and the mechanism of black tea (BT) polyphenols and polysaccharides in male Sprague-Dawley rats. The BT polyphenols and polysaccharides reduced the body weight, Lee's index, visceral fat weight, and fat cell size but improved the biochemical profile and increased the fecal fatty acid content, thereby preventing high-fat diet-induced obesity. A gene expression profile array was used to screen eight upregulated and five downregulated differentially expressed genes that affect fat metabolic pathways, such as glycerolipid and glycerophospholipid metabolism, fatty acid degradation, glycolysis and gluconeogenesis, bile and pancreatic secretion, the insulin signaling pathway, and steroid hormone secretion. The BT polyphenols and polysaccharides suppressed the formation and accumulation of fat and promoted its decomposition to prevent obesity. PMID:27161951

  1. Confirming and improving post-Newtonian and effective-one-body results from self-force computations along eccentric orbits around a Schwarzschild black hole

    CERN Document Server

    Bini, Donato; Geralico, Andrea

    2015-01-01

    We analytically compute, through the six-and-a-half post-Newtonian order, the second-order-in-eccentricity piece of the Detweiler-Barack-Sago gauge-invariant redshift function for a small mass in eccentric orbit around a Schwarzschild black hole. Using the first law of mechanics for eccentric orbits [A. Le Tiec, Phys. Rev. D {\\bf 92}, 084021 (2015)] we transcribe our result into a correspondingly accurate knowledge of the second radial potential of the effective-one-body formalism [A. Buonanno and T. Damour, Phys. Rev. D {\\bf 59}, 084006 (1999)]. We compare our newly acquired analytical information to several different numerical self-force data and find good agreement, within estimated error bars. We also obtain, for the first time, independent analytical checks of the recently derived, comparable-mass fourth-post-Newtonian order dynamics [T. Damour, P. Jaranowski and G. Shaefer, Phys. Rev. D {\\bf 89}, 064058 (2014)].

  2. Effective one body Hamiltonian of two spinning black-holes with next-to-next-to-leading order spin-orbit coupling

    CERN Document Server

    Nagar, Alessandro

    2011-01-01

    Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian (PN) spin-orbit Hamiltonian for spinning binaries \\cite{Hartung:2011te} we extend the effective-one-body (EOB) description of the dynamics of two spinning black-holes to NNLO in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order (NLO) spin-orbit Hamiltonian computed in Ref. \\cite{Damour:2008qf}. The present EOB Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the NLO spin-orbit coupling.

  3. A high absorbance material for solar collectors' applications

    International Nuclear Information System (INIS)

    In this work, we proposed a low cost material to be used as an excellent absorber for solar collectors, to increase its thermal efficiency by the high capacity to absorb solar radiation. The material, known as 'smoke black' (soot) can be obtained by the incomplete combustion of organic materials, such as the oxygen-acetylene, paraffin, or candles. A comparative analysis between the optical properties (reflectance, absorbance, and emissivity) measured on three covered copper surfaces (without paint, with a commercial matte black paint, and with smoke black) shows amazing optical results for the smoke black. Reflectance values of the smoke black applied over copper surfaces improves 56 times the values obtained from commercial black paints. High values of emissivity (E=0.9988) were measured on the surface covered with smoke black by spectrophotometry in the UV-VIS range, which represents about 7% of increment as compared with the value obtained for commercial black paints (E=0.938). The proposed high absorbance material can be easily applied on any kind of surfaces at low cost.

  4. Self-Reported Eating Disorders of Black, Low-Income Adolescents: Behavior, Body Weight Perceptions, and Methods of Dieting.

    Science.gov (United States)

    Balentine, Margaret; And Others

    1991-01-01

    Study identified African-American low-income adolescents who thought they had bulimia or anorexia nervosa, identified common behaviors, and compared actual and perceived body weight and dieting methods. About 12 percent suspected an eating disorder and perceived themselves as heavier more often than their peers. Fasting was the most common dieting…

  5. Effective one-body Hamiltonian of two spinning black holes with next-to-next-to-leading order spin-orbit coupling

    Science.gov (United States)

    Nagar, Alessandro

    2011-10-01

    Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian spin-orbit Hamiltonian for spinning binaries [J. Hartung and J. Steinhoff, arXiv:1104.3079.] we improve the effective-one-body description of the dynamics of two spinning black holes by including NNLO effects in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order spin-orbit Hamiltonian computed in [T. Damour, P. Jaranowski, and G. Schaefer, Phys. Rev. DPRVDAQ1550-7998 78, 024009 (2008).10.1103/PhysRevD.78.024009]. The present effective-one-body Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the next-to-leading order spin-orbit coupling.

  6. Research of the dynamics of a magnetic fluid dynamic absorber

    International Nuclear Information System (INIS)

    A new type of shock absorber using a magnetic fluid drop with the permanent magnet inside as a working element is investigated in this paper. Movement of the working element inside the body of the absorber under the influence of external oscillatory inertia forces leads to a viscous dissipation of the oscillating system energy. A theoretical model and some characteristics of the absorber are presented. This type of dynamic absorber is used nowadays in spacecraft technology

  7. Methods for absorbing neutrons

    Science.gov (United States)

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  8. Burnable neutron absorber element

    International Nuclear Information System (INIS)

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber

  9. Burnable neutron absorber element

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, H.M.

    1988-06-14

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber.

  10. Warm Absorber Diagnostics of AGN Dynamics

    Science.gov (United States)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  11. Reflection from black holes

    CERN Document Server

    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.

  12. Cylinder light concentrator and absorber: theoretical description

    OpenAIRE

    Kildishev, Alexander V.; Prokopeva, Ludmila J.; Narimanov, Evgenii

    2010-01-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the d...

  13. Binary black hole coalescence in the extreme-mass-ratio limit: Testing and improving the effective-one-body multipolar waveform

    International Nuclear Information System (INIS)

    We discuss the properties of the effective-one-body (EOB) multipolar gravitational waveform emitted by nonspinning black-hole binaries of masses μ and M in the extreme-mass-ratio limit μ/M=ν-4 rad and maintain then a remarkably accurate phase coherence during the long inspiral (∼33 orbits), accumulating only about -2x10-3 rad until the last stable orbit, i.e. Δφ/φ∼-5.95x10-6. We obtain such accuracy without calibrating the analytically resummed EOB waveform to numerical data, which indicates the aptitude of the EOB waveform for studies concerning the Laser Interferometer Space Antenna. We then improve the behavior of the EOB waveform around merger by introducing and tuning next-to-quasicircular corrections in both the gravitational wave amplitude and phase. For each multipole we tune only four next-to-quasicircular parameters by requiring compatibility between EOB and Regge-Wheeler-Zerilli waveforms at the light ring. The resulting phase difference around the merger time is as small as ±0.015 rad, with a fractional amplitude agreement of 2.5%. This suggest that next-to-quasicircular corrections to the phase can be a useful ingredient in comparisons between EOB and numerical-relativity waveforms.

  14. Ten shades of black

    CERN Document Server

    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...

  15. Black to Black

    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...

  16. TOMS Absorbing Aerosol Index

    Data.gov (United States)

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  17. Metasurface Broadband Solar Absorber

    OpenAIRE

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Milan Sykora; Nina R. Weisse-Bernstein; Luk, Ting S.; Antoinette J. Taylor; Dalvit, Diego A. R.; Hou-Tong Chen

    2016-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experiment...

  18. Universality in grey-body radiance: Extending Kirchoff's law to the statistics of quanta

    International Nuclear Information System (INIS)

    An ideal grey body is a macroscopic object with definite temperature which absorbs only a fraction of the radiation incident on it. Assuming that a grey body always emits in a mixed state, and that the radiation density matrix factors into matrices for the various frequency modes, we employ general arguments to derive the complete statistic of grey-body radiance elicited by incident radiation. These depend only on the temperature and the absorptivities for the various frequencies (hence are of universal form), and coincide with the statistics of black-hole radiance first derived a decade and a half ago

  19. Antigravity and black holes

    CERN Document Server

    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.

  20. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  1. 低温点源黑体关键技术及国内外发展现状%Key technologies and development of point-source black body working at low temperature

    Institute of Scientific and Technical Information of China (English)

    许杰; 杨林华; 李娜

    2011-01-01

    文章分析了低温点源黑体设备研制中的几项关键技术,包括3种常见发射腔腔形的特点,腔体发射率的计算方法,以及热管,恒温浴和液氮电加热3种恒温方式的原理和技术特性;比较了国内外典型低温黑体设备、产品的性能指标;并简述低温点源黑体设备在红外定标试验中的原理和应用.最后总结出现阶段低温点源黑体的发展水平以及未来的研究重点.%In this paper, some key technologies of point-source black body working at low temperature are analyzed, including the features of three kinds of black body cavities, the emissivity calculation methods, and the principle of maintaining the temperature of the cavity with heat pipe, water or oil bath, or liquid nitrogen and electric heater. The characteristics of the facilities developed in China and other countries are compared, the principle and applications of this kind of black body in the radiometric calibration experimentation are discussed in details. Finally, the development level and future concerns related with this kind of facilities are discussed.

  2. Perfect absorbers on curved surfaces and their potential applications.

    Science.gov (United States)

    Alaee, Rasoul; Menzel, Christoph; Rockstuhl, Carsten; Lederer, Falk

    2012-07-30

    Recently perfect metamaterial absorbers triggered some fascination since they permit the observation of an extreme interaction of light with a nanostructured thin film. For the first time we evaluate here the functionality of such perfect absorbers if they are applied on curved surfaces. We probe their optical response and discuss potential novel applications. Examples are the complete suppression of back-scattered light from the covered objects, rendering it cloaked in reflection, and their action as optical black holes. PMID:23038388

  3. Thermal performance of linear Fresnel reflecting solar concentrator with trapezoidal cavity absorbers

    International Nuclear Information System (INIS)

    Thermal performance of the four identical trapezoidal cavity absorbers for linear Fresnel reflecting solar device were studied and compared. The absorbers were designed for operating in conjunction with a prototype Fresnel solar reflector. Rectangular and round pipe sections were used as absorber by placing in the trapezoidal cavity. The absorber pipes were coated with ordinary dull black board paint and black nickel selective surface. The bottom of the cavity was provided with plane glass to allow the solar radiation to be reflected from the Fresnel reflector. The other three sides of the cavity absorber were insulated to reduce heat loss. Thermal performance of the Fresnel reflecting concentrator with each trapezoidal cavity absorber was studied experimentally at different concentration ratio of the reflector. The study revealed that the thermal efficiency was influenced by the concentration ratio and selective surface coating on the absorber. The thermal efficiency decreased with the increase in the concentration ratio of the Fresnel reflecting collector. The selective surface coated absorber had a significant advantage in terms of superior thermal performance as compared to ordinary black painted absorber. The round pipe (multi-tube) receiver had higher surface area to absorb solar energy as compared to rectangular pipe receiver. Thermal efficiency of the solar device with round pipe absorber was found higher (up to 8%) as compared to rectangular pipe absorber.

  4. Front-end Combination Component Of Fixed Mask And Absorber

    International Nuclear Information System (INIS)

    A front-end combination component of fixed mask and absorber is a device that combines a fixed mask and a photon absorber in one body to save space, setup work and maintenance in the photon beamline front-end. The SPring-8 undulator absorber consists of an upper V-shaped photon absorber part and a lower rectangular beam-transfer channel part. The upper wall of the beam-transfer channel is cut in the V-shape notch as the photon absorber. The combination component design based on the absorber is adopted. The photon duct part is modified in the shape of the fixed mask. The combination component moves up and down. In the upper limit, it acts as the mask and the beam-transfer channel. In the lower limit, it acts as the photon absorber. Design details of the component and its commissioning are presented

  5. 地铁车辆吸能装置耐碰撞性分析%Analysis of Crashworthiness of Energy-Absorbing Component in the Metro Vehicle Car-body

    Institute of Scientific and Technical Information of China (English)

    韩增盛; 马松花

    2012-01-01

    吸能装置是确保地铁列车具有良好耐碰撞性能的一种重要部件.为实现地铁车辆吸能装置的结构优化,采用有限元分析软件ANSYS/LS-DYNA对不同厚度、不同横截面形状的薄壁结构碰撞性进行了仿真分析,分析结果表明,吸能装置的性能与其横截面的形状、壁厚的选择紧密相关.条件相同时,吸能装置的吸能能力与壁厚成正比,但壁厚增加时,界面力也随之增大,在吸能结构的设计中,需综合考虑.以地铁头车为研究对象,对安装了吸能装置的地铁头车进行了碰撞仿真,得到车体吸能装置碰撞过程变形情况和碰撞能量-时间历程,结果表明该结构吸能装置具有良好的吸能特性.%Energy-absorbing structure is an important component to ensure that the metro train has a good crashworthiness. In order to realize the optimization of the energy-absorbing structure, finite element analysis software ANSYS/LS-DYNA is used to simulate the crash performance of thin-wall structures of various thickness, cross-section. The results show that the performance of energy-absorbing component is closely related to cross section and thickness. The same conditions, absorption capability of energy-absorbing component is proportional to thickness, however,interface force increases with the increase of thickness,therefore,in the design of energy-absorbing component,it is necessary to consider it fully. Take the metro vehicle for example,one metro vehicle equipped with the energy absorption component is put up to simulate the collision procedure, and the deformation of the energy-absorbing component and the collision energy-time course are obtained, the results show that this energy-absorbing component has good energy absorption performance.

  6. Metasurface Broadband Solar Absorber

    CERN Document Server

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  7. An absorbed dose microcalorimeter

    International Nuclear Information System (INIS)

    A graphite microcalorimeter is described for use as a primary standard of ionising radiation absorbed dose; its place in the hierarchy of Australian ionising radiation standards is discussed. A disc shaped absorber is supported on pins within three nested graphite jackets and an insulated vacuum vessel. Calibration heating is by thermistor, the feasibility of this was verified by computer modelling. Adiabatic and heat-flow modes of operation are described, and calculations of heat transfer between the various graphite parts are summarised. Carbon and water phantoms were built for the evaluation of correction factors for the microcalorimeter, and for the calibration of radiotherapy dosemeters. The microcalorimeter will be used as a working standard for the calibration of dosemeters in terms of absorbed dose for the x-ray, gamma-ray and electron radiotherapy beams commonly used in Australia today

  8. Absorbent material for type a radioactive materials packaging containing liquids

    International Nuclear Information System (INIS)

    The application of absorbent materials to the packaging and transport of liquid radioactive materials in Type A packages has not been reported in the literature. However, a significant body of research exists on absorbent materials for personal hygiene products such as diapers. Absorption capacity is dependent on both the absorbent material and the liquid being absorbed. Theoretical principles for capillary absorption in both the horizontal and the vertical plane indicate that small contact angle between the absorbent fibre and the liquid, and a small inter-fibre pore size are important. Some fluid parameters such as viscosity affect the rate of absorption but not the final absorption capacity. There appears to be little comparability between results obtained for the same absorbent and fluid using different test procedures. Test samples of materials from several classes of potential absorbents have been evaluated in this study, and shown to have a wide range of absorbent capacities. Foams, natural fibres, artificial fibres and granular materials are all potentially useful absorbents, with capacities ranging from as little as 0.86 to as much as 40.6 grams of distilled water per gram of absorbent. Two experimental procedures for evaluating the absorbent capacity of these materials have been detailed in this report, and found suitable for evaluating granular, fibrous or foam materials. Compression of the absorbent material reduces its capacity, but parameters such as relative humidity, pH, temperature, and viscosity appear to have little significant influence on capacity. When the materials were loaded to 50% of their one-minute absorbency, subsequent loss of the absorbed liquid was generally minimal. All of the absorbent materials rapidly lost their absorbed water through evaporation within twenty-four hours in still air at 21 degrees C and 50% relative humidity

  9. Hydroxyl radical and NOx production rates, black carbon concentrations and light-absorbing impurities in snow from field measurements of light penetration and nadir reflectivity of onshore and offshore coastal Alaskan snow

    Science.gov (United States)

    France, J. L.; Reay, H. J.; King, M. D.; Voisin, D.; Jacobi, H. W.; Domine, F.; Beine, H.; Anastasio, C.; MacArthur, A.; Lee-Taylor, J.

    2012-07-01

    Photolytic production rates of NO, NO2 and OH radicals in snow and the total absorption spectrum due to impurities in snowpack have been calculated for the Ocean-Atmosphere-Sea-Ice-Snowpack (OASIS) campaign during Spring 2009 at Barrow, Alaska. The photolytic production rate and snowpack absorption cross-sections were calculated from measurements of snowpack stratigraphy, light penetration depths (e-folding depths), nadir reflectivity (350-700 nm) and UV broadband atmospheric radiation. Maximum NOx fluxes calculated during the campaign owing to combined nitrate and nitrite photolysis were calculated as 72 nmol m-2 h-1 for the inland snowpack and 44 nmol m-2 h-1 for the snow on sea-ice and snowpack around the Barrow Arctic Research Center (BARC). Depth-integrated photochemical production rates of OH radicals were calculated giving maximum OH depth-integrated production rates of ˜160 nmol m-2 h-1 for the inland snowpack and ˜110-120 nmol m-2 h-1 for the snow around BARC and snow on sea-ice. Light penetration (e-folding) depths at a wavelength of 400 nm measured for snowpack in the vicinity of Barrow and snow on sea-ice are ˜9 cm and 14 cm for snow 15 km inland. Fitting scaled HULIS (HUmic-LIke Substances) and black carbon absorption cross-sections to the determined snow impurity absorption cross-sections show a "humic-like" component to snowpack absorption, with typical concentrations of 1.2-1.5 μgC g-1. Estimates of black carbon concentrations for the four snowpacks are ˜40 to 70 ng g-1 for the terrestrial Arctic snowpacks and ˜90 ng g-1 for snow on sea-ice.

  10. Black Hole Masses are Quantized

    CERN Document Server

    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...

  11. Black rings

    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)

  12. The passage of lanthanides (Cd-144, Nd-147, Sm-153, Eu-155 and Tb-160) into fetus and newborn after intravenous contamination of rats and estimation of absorbed dose in whole body and gastrointestinal tract

    International Nuclear Information System (INIS)

    The purpose of the study was the determination of the passage of certain lanthanum elements (147Nd, 153Sm, 155Eu and 160Tb) from maternal blood through the placenta to the fetus in the second and third weeks of pregnancy and also estimation of absorbed dose in gastrointestinal tract in newborn rats contaminated with 147Nd, 153Sm, 155Eu and 160Tb. The study demonstrated that the lanthanum elements passed across the placental barrier. Placental retention was several times higher in late pregnancy (in the case of 160Tb it was even 16 - fold greater). In the last period of pregnancy this passage increased with increasing mass number of the elements (Nd160Tb (17%) and decreased with the drop of molecular weight of radionuclides. For all lanthanides tested, the dose of γ-radiation absorbed by newborns could be neglected since it comprised only 0.5% of β-radiation. The absorbed dose of β-radiation during the first week of life of new newborns fed by mother injected with 37 kBq of radionuclides ranged from 204 mGy for 160Tb to 0.23 mGy for 144Ce. (author). 15 refs., 5 figs., 4 tabs

  13. Negative impedance shunted electromagnetic absorber for broadband absorbing: experimental investigation

    International Nuclear Information System (INIS)

    The traditional tuned mass absorber is widely employed to control the vibration of a primary structure by transferring the vibrating energy to the absorber. However, the working band of the absorber is very narrow, which limits the application of broadband vibration control. This study presents a novel broadband electromagnetic absorber by first introducing two negative impedance shunts to improve broadband damping of the absorber. The electromagnetic absorber is modeled, and the corresponding electromagnetic coupling coefficient is tested. A cantilever beam is employed to verify the broadband vibration absorption of the negative resistance (NR) shunted electromagnetic absorber (NR absorber) and the negative inductance NR shunted electromagnetic absorber (NINR absorber). The governing equations of the beam with two absorbers are derived, and the experiments are set up. The results point out that the NR and NINR absorbers can attenuate the broadband vibration. The proposed absorbers do not need the feedback system and the real-time controller compared to the active absorber; hence, they have great application potential in aerospace and in submarine applications, as well as in civil and mechanical engineering. (paper)

  14. The Two-Phase, Two-Velocity Ionized Absorber in the Seyfert 1 Galaxy NGC 5548

    CERN Document Server

    Andrade-Velázquez, M; Elvis, M; Nicastro, F; Brickhouse, N; Binette, L; Mathur, S; Jiménez-Bailón, E

    2010-01-01

    We present an analysis of X-ray high quality grating spectra of the Seyfert 1 galaxy NGC 5548 using archival Chandra HETGS and LETGS observations for a total exposure time of 800ks. The continuum emission is well represented by a powerlaw plus a black-body component. We find that the well known X-ray warm absorber in this source consists of two different outflow velocity systems. Recognizing the presence of these kinematically distinct components allows each system to be fitted independently, each with two absorption components with different ionization levels. The high velocity system consists of a component with temperature of 2.7X10^6K and another component with temperature of 5.8X10^5K. The low-velocity system required also two absorbing components, one with temperature of 5.8X10^5K; the other with lower temperature (3.5X10^4K). Once these components are considered, the data do not require any further absorbers. In particular, a model consisting of a continuous radial range of ionization structures is not...

  15. Cylinder light concentrator and absorber: theoretical description.

    Science.gov (United States)

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  16. Possible Effects of a Cosmological Constant on Black Hole Evolution

    OpenAIRE

    Adams, Fred C.; Mbonye, Manasse; Laughlin, Gregory

    1999-01-01

    We explore possible effects of vacuum energy on the evolution of black holes. If the universe contains a cosmological constant, and if black holes can absorb energy from the vacuum, then black hole evaporation could be greatly suppressed. For the magnitude of the cosmological constant suggested by current observations, black holes larger than $\\sim 4 \\times 10^{24}$ g would accrete energy rather than evaporate. In this scenario, all stellar and supermassive black holes would grow with time un...

  17. Metasurface Broadband Solar Absorber

    Science.gov (United States)

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  18. Universal metamaterial absorbe

    CERN Document Server

    Smaali, Rafik; Moreau, Antoine; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal.

  19. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  20. Universal metamaterial absorbe

    OpenAIRE

    Smaali, Rafik; Omei, Fatima; Antoine MOREAU; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by...

  1. Burnable neutron absorbers

    International Nuclear Information System (INIS)

    This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al2O3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B4C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

  2. 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

  3. Absorber for terahertz radiation management

    Science.gov (United States)

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  4. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  5. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  6. Effective Field Theoretical Approach to Black Hole Production

    OpenAIRE

    Bilke, Sven; Lipartia, Edisher; Maul, Martin

    2002-01-01

    A field theoretical description of mini black hole production at TeV energies is given taking into account the quantization of black holes in discrete resonances. The unknown quantum gravitational effects are absorbed in effective couplings, black hole masses and the Hawking temperature. The evaporation is described in terms of thermal field theory.

  7. Black Consciousness

    Science.gov (United States)

    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…

  8. Sensing with THz metamaterial absorbers

    CERN Document Server

    Cong, Longqing

    2014-01-01

    Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

  9. Pyrolytic carbon coated black silicon.

    Science.gov (United States)

    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

  10. Black holes and beyond

    International Nuclear Information System (INIS)

    's research councils have yet to put any real money behind these ideas. Black holes are best described by the general theory of relativity. However, general relativity is a classical theory of gravity, and although its predictions have been verified in many experiments, a quantum theory of gravity remains one of the holy grails of physics. One of the first physicists to make real progress in this quest to reconcile general relativity and quantum mechanics was Stephen Hawking. In 1974 Hawking calculated what would happen if a quantum fluctuation occurred near an event horizon. He concluded that the black hole would radiate, and that the amount of radiation would be inversely proportional to the mass of the black hole. However, black holes tend to be very heavy, so their output of Hawking radiation would be too low to detect experimentally. One intriguing exception could be much smaller primordial black holes created in the big bang: these should radiate observable amounts of gamma rays, but they have not been detected yet. This whole body of work - in which thermodynamic concepts such as temperature and entropy are also associated with the black hole - is Hawking's major achievement in physics. The detection of Hawking radiation is the ultimate goal of experiments on artificial black holes, although a lot of theoretical and experimental work has to be done first. The successful experiment is likely to involve a flowing Bose-Einstein condensate or a medium in which the speed of light can be reduced to zero. After years of groundwork, physicists have recently made rapid progress in both these fields. Meanwhile, the recent observation of neutrons in discrete quantum states in a gravitational potential shows that quantum gravity effects can be seen in the laboratory. All that is needed now is an act of faith. (U.K.)

  11. Asymmetric black dyonic holes

    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.

  12. Inferring Absorbing Organic Carbon Content from AERONET Data

    Science.gov (United States)

    Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

    2011-01-01

    Black carbon, light-absorbing organic carbon (often called brown carbon) and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated globally the amount of light absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South-America and Africa are relatively high (about 15-20 magnesium per square meters during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 magnesium per square meters during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while opposite is true in urban areas in India and China.

  13. Heterogeneous neutron absorbers development

    International Nuclear Information System (INIS)

    The use of solid burnable absorber materials in power light water reactors has increased in the last years, specially due to improvements attained in costs of generated electricity. The present work summarizes the basic studies made on an alumina-gadolinia system, where alumina is the inert matrix and gadolinia acts as burnable poison, and describes the fabrication method of pellets with that material. High density compacts were obtained in the range of concentrations used by cold pressing and sintering at 1600 deg C in inert (Ar) atmosphere. Finally, the results of the irradiation experiences made at RA-6 reactor, located at the Bariloche Atomic Center, are given where variations on negative reactivity caused by introduction of burnable poison rods were measured. The results obtained from these experiences are in good agreement with those coming from calculation codes. (Author)

  14. Selective coating for solar panels. [using black chrome and black nickel

    Science.gov (United States)

    Mcdonald, G. E. (Inventor)

    1977-01-01

    The energy absorbing properties of solar heating panels are improved by depositing a black chrome coating of controlled thickness on a specially prepared surface of a metal substrate. The surface is prepared by depositing a dull nickel on the substrate, and the black chrome is plated on this low emittance surface to a thickness between 0.5 micron and 2.5 microns.

  15. Microscopic modeling of nitride intersubband absorbance

    Science.gov (United States)

    Montano, Ines; Allerman, A. A.; Wierer, J. J.; Moseley, M.; Skogen, E. J.; Tauke-Pedretti, A.; Vawter, G. A.

    III-nitride intersubband structures have recently attracted much interest because of their potential for a wide variety of applications ranging from electro-optical modulators to terahertz quantum cascade lasers. To overcome present simulation limitations we have developed a microscopic absorbance simulator for nitride intersubband devices. Our simulator calculates the band structure of nitride intersubband systems using a fully coupled 8x8 k.p Hamiltonian and determines the material response of a single period in a density-matrix-formalism by solving the Heisenberg equation including many-body and dephasing contributions. After calculating the polarization due to intersubband transitions in a single period, the resulting absorbance of a superlattice structure including radiative coupling between the different periods is determined using a non-local Green's-function formalism. As a result our simulator allows us to predict intersubband absorbance of superlattice structures with microscopically determined lineshapes and linewidths accounting for both many-body and correlation contributions. This work is funded by Sandia National Laboratories Laboratory Directed Research and Development program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin.

  16. An electromagnetic black hole made of metamaterials

    CERN Document Server

    Cheng, Qiang

    2009-01-01

    Traditionally, a black hole is a region of space with huge gravitational field in the means of general relativity, which absorbs everything hitting it including the light. In general relativity, the presence of matter-energy densities results in the motion of matter propagating in a curved spacetime1, which is similar to the electromagnetic-wave propagation in a curved space and in an inhomogeneous metamaterial2. Hence one can simulate the black hole using electromagnetic fields and metamaterials. In a recent theoretical work, an optical black hole has been proposed based on metamaterials, in which the numerical simulations showed a highly efficient light absorption3. Here we report the first experimental demonstration of electromagnetic black hole in the microwave frequencies. The proposed black hole is composed of non-resonant and resonant metamaterial structures, which can absorb electromagnetic waves efficiently coming from all directions due to the local control of electromagnetic fields. Hence the elect...

  17. Phantoms for diffuse optical imaging based on totally absorbing objects, part 2: experimental implementation

    Science.gov (United States)

    Martelli, Fabrizio; Ninni, Paola Di; Zaccanti, Giovanni; Contini, Davide; Spinelli, Lorenzo; Torricelli, Alessandro; Cubeddu, Rinaldo; Wabnitz, Heidrun; Mazurenka, Mikhail; Macdonald, Rainer; Sassaroli, Angelo; Pifferi, Antonio

    2014-07-01

    We present the experimental implementation and validation of a phantom for diffuse optical imaging based on totally absorbing objects for which, in the previous paper [J. Biomed. Opt. 18(6), 066014, (2013)], we have provided the basic theory. Totally absorbing objects have been manufactured as black polyvinyl chloride (PVC) cylinders and the phantom is a water dilution of intralipid-20% as the diffusive medium and India ink as the absorber, filled into a black scattering cell made of PVC. By means of time-domain measurements and of Monte Carlo simulations, we have shown the reliability, the accuracy, and the robustness of such a phantom in mimicking typical absorbing perturbations of diffuse optical imaging. In particular, we show that such a phantom can be used to generate any absorption perturbation by changing the volume and position of the totally absorbing inclusion.

  18. Energy-absorbing effectiveness factor

    OpenAIRE

    Jones, Norman

    2010-01-01

    Abstract A study is reported on the energy-absorbing effectiveness factor which was introduced recently. The factor is defined as the quotient of the total energy, which can be absorbed in a system, to the maximum energy up to failure in a normal tensile specimen, which is made from the same volume of material. This dimensionless parameter allows comparisons to be made of the effectiveness of various geometrical shapes and of energy-absorbers made from different materials. The infl...

  19. Casimir force in absorbing multilayers

    OpenAIRE

    Tomas, M. S.

    2002-01-01

    The Casimir effect in a dispersive and absorbing multilayered system is considered adopting the (net) vacuum-field pressure point of view to the Casimir force. Using the properties of the macroscopic field operators appropriate for absorbing systems and a convenient compact form of the Green function for a multilayer, a straightforward and transparent derivation of the Casimir force in a lossless layer of an otherwise absorbing multilayer is presented. The resulting expression in terms of the...

  20. Black Eye

    Science.gov (United States)

    ... 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 ...

  1. Black tea

    Science.gov (United States)

    ... 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, ...

  2. Are ethnic and gender specific equations needed to derive fat free mass from bioelectrical impedance in children of South asian, black african-Caribbean and white European origin? Results of the assessment of body composition in children study.

    Directory of Open Access Journals (Sweden)

    Claire M Nightingale

    Full Text Available BACKGROUND: Bioelectrical impedance analysis (BIA is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 South Asians, 250 black African-Caribbeans and 289 white Europeans with measurements of height, weight and arm-leg impedance (Z; Bodystat 1500. Total body water was estimated from deuterium dilution and converted to FFM. Multilevel models were used to derive three types of equation {A: FFM = linear combination(height+weight+Z; B: FFM = linear combination(height(2/Z; C: FFM = linear combination(height(2/Z+weight}. RESULTS: Ethnicity and gender were important predictors of FFM and improved model fit in all equations. The models of best fit were ethnicity and gender specific versions of equation A, followed by equation C; these provided accurate assessments of ethnic differences in FFM and FM. In contrast, the use of generic equations led to underestimation of both the negative South Asian-white European FFM difference and the positive black African-Caribbean-white European FFM difference (by 0.53 kg and by 0.73 kg respectively for equation A. The use of generic equations underestimated the positive South Asian-white European difference in fat mass (FM and overestimated the positive black African-Caribbean-white European difference in FM (by 4.7% and 10.1% respectively for equation A. Consistent results were observed when the equations were applied to a large external data set. CONCLUSIONS: Ethnic- and gender-specific equations for predicting FFM from BIA provide better estimates of ethnic differences in FFM and FM in children, while generic equations

  3. The Physicochemical Changes of Black Garlic during Thermal Processing

    Directory of Open Access Journals (Sweden)

    Mengmeng Lei

    2015-03-01

    Full Text Available To explore the physicochemical changes of black garlic during the thermal processing steps and further reveal the role of Maillard reaction in the formation mechanism of black garlic. The physicochemical changes including UV-Vis absorbance, fluorescence and color difference were determined. The UV absorbance at 294 nm and browning intensity at 420 nm gradually increased with increasing heating time, while the fluorescence intensity showed a maximum value at the heating time of 3 days. The color value of black garlic increased after heating at 70-80°C for 10 days. These results indicated Maillard reaction was primarily responsible for the formation of black garlic.

  4. The Transition from Inspiral to Plunge for a Compact Body in a Circular Equatorial Orbit Around a Massive, Spinning Black Hole

    CERN Document Server

    Ori, A; Ori, Amos; Thorne, Kip S.

    2000-01-01

    There are three regimes of gravitational-radiation-reaction-induced inspiralfor a compact body with mass mu, in a circular, equatorial orbit around a Kerrblack hole with mass M>>mu: (i) The "adiabatic inspiral regime", in which thebody gradually descends through a sequence of circular, geodesic orbits. (ii) A"transition regime", near the innermost stable circular orbit (isco). (iii) The"plunge regime", in which the body travels on a geodesic from slightly belowthe isco into the hole's horizon. This paper gives an analytic treatment of thetransition regime and shows that, with some luck, gravitational waves from thetransition might be measurable by the space-based LISA mission.

  5. 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

  6. Black Holes

    Science.gov (United States)

    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.

  7. Energy absorber for the CETA

    Science.gov (United States)

    Wesselski, Clarence J.

    1994-05-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  8. Energy absorber for the CETA

    Science.gov (United States)

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  9. Leaf absorbance and photosynthesis

    Science.gov (United States)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  10. Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism

    OpenAIRE

    Eugeny F. Orlov

    2012-01-01

    The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.

  11. Center of Mass of Two or More Celestial Bodies as a Basis of Comets and «Black Holes» Mechanism

    Directory of Open Access Journals (Sweden)

    Eugeny F. Orlov

    2012-04-01

    Full Text Available The article considers the questions, arising during rendezvous of two celestial bodies with equal mass, one of which is the Earth and the consequences of such rendezvous to modern civilization, suggests the idea of centers of galaxies mass with anomalously large values of the gravitational fields, which allows to divide them into two types – material filled and hollow.

  12. The dynamics analysis of a ferrofluid shock absorber

    Science.gov (United States)

    Yao, Jie; Chang, Jianjun; Li, Decai; Yang, Xiaolong

    2016-03-01

    The paper presents a shock absorber using three magnets as the inertial mass. Movement of the inertial mass inside a cylindrical body filled with ferrofluid will lead to a viscous dissipation of the oscillating system energy. The influence of a dumbbell-like ferrofluid structure on the energy dissipation is considered and the magnetic restoring force is investigated by experiment and theoretical calculation. A theoretical model of the hydrodynamics and energy dissipation processes is developed, which includes the geometrical characteristics of the body, the fluid viscosity, and the external magnetic field. The theory predicts the experimental results well under some condition. The shock absorber can be used in spacecraft technology.

  13. Brown carbon: a significant atmospheric absorber of solar radiation?

    Directory of Open Access Journals (Sweden)

    Y. Feng

    2013-09-01

    Full Text Available Several recent observational studies have shown organic carbon aerosols to be a significant source of absorption of solar radiation. The absorbing part of organic aerosols is referred to as "brown" carbon (BrC. Using a global chemical transport model and a radiative transfer model, we estimate for the first time the enhanced absorption of solar radiation due to BrC in a global model. The simulated wavelength dependence of aerosol absorption, as measured by the absorption Ångström exponent (AAE, increases from 0.9 for non-absorbing organic carbon to 1.2 (1.0 for strongly (moderately absorbing BrC. The calculated AAE for the strongly absorbing BrC agrees with AERONET spectral observations at 440–870 nm over most regions but overpredicts for the biomass burning-dominated South America and southern Africa, in which the inclusion of moderately absorbing BrC has better agreement. The resulting aerosol absorption optical depth increases by 18% (3% at 550 nm and 56% (38% at 380 nm for strongly (moderately absorbing BrC. The global simulations suggest that the strongly absorbing BrC contributes up to +0.25 W m−2 or 19% of the absorption by anthropogenic aerosols, while 72% is attributed to black carbon, and 9% is due to sulfate and non-absorbing organic aerosols coated on black carbon. Like black carbon, the absorption of BrC (moderately to strongly inserts a warming effect at the top of the atmosphere (TOA (0.04 to 0.11 W m−2, while the effect at the surface is a reduction (−0.06 to −0.14 W m−2. Inclusion of the strongly absorption of BrC in our model causes the direct radiative forcing (global mean of organic carbon aerosols at the TOA to change from cooling (−0.08 W m−2 to warming (+0.025 W m−2. Over source regions and above clouds, the absorption of BrC is higher and thus can play an important role in photochemistry and the hydrologic cycle.

  14. Dancing with black holes

    CERN Document Server

    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.

  15. Melanin pigmentation gives rise to black spots on the wings of the silkworm Bombyx mori.

    Science.gov (United States)

    Ito, Katsuhiko; Yoshikawa, Manabu; Fujii, Takeshi; Tabunoki, Hiroko; Yokoyama, Takeshi

    2016-01-01

    Several mutants of the silkworm Bombyx mori show body color variation at the larval and adult stages. The Wild wing spot (Ws) mutant exhibits a phenotype in which the moth has a spot on the apex of the forewing. In this study, we investigated this trait to elucidate the molecular mechanism underlying the color pattern. Microscopy of the black spot of Ws mutants showed that the pigment emerges in the scales of the wing, and accumulation of the pigment becomes strong just before eclosion. We next examined the relationship between the black spot of the Ws mutant and melanin. The spectrophotometry using alkaline extracts from the black spot in the wing showed the highest absorption intensity at 405nm, which is the absorbance wavelength of melanin. Moreover, inhibition assays for enzymes implicated in melanin synthesis using 3-iodo-l-tyrosine (a tyrosine hydroxylase inhibitor) and L-α-methyl-DOPA (a dopa decarboxylase inhibitor) revealed that treatment with each inhibitor disrupted the pigmentation of the wing of the Ws mutant. On the basis of these results, we analyzed the expression pattern of five genes involved in melanin formation, and found that the expression levels of yellow and laccase2 were increased just before pigmentation, whereas those of DDC, tan, and TH were increased when the apex of the wing turned black. These results showed that melanin pigmentation gives rise to the black spot on the wing. PMID:27405010

  16. Heat loss study of trapezoidal cavity absorbers for linear solar concentrating collector

    International Nuclear Information System (INIS)

    There should be minimum heat loss from the absorber to achieve better efficiency of the solar collector. Overall heat loss coefficients of the trapezoidal cavity absorber with rectangular and round pipe were studied in the laboratory. Two identical rectangular pipe absorbers (section size: 100 x 23 mm, thickness: 2.5 mm and length 2170 mm) and two round pipe absorbers (a set of six mild steel round tubes of 16 mm diameter and 2.5 mm thickness brazed together in single layer making 100 mm width) were fabricated. A rectangular and a round pipe were painted with ordinary mat black paint (emissivity at 100 deg. C = 0.91) and one pipe of each type was coated with black nickel selective surface (emissivity at 100 deg. C = 0.17). Overall heat loss coefficient of the absorber was studied by circulating hot oil through it at different temperatures. The heat loss coefficient was increased with the absorber temperature. The heat loss coefficients for ordinary black coated and selective surface coated round pipe absorbers were varied from 3.5 to 7.5 W/m2/ deg. C and 2.7-5.8 W/m2/ deg. C respectively. The rectangular pipe section has marginally higher heat loss coefficients as compared to round pipe absorber. Selective surface coating on the absorbers reduced heat loss coefficient significantly by 20-30% as compared to ordinary black coating. The double glass cover also reduced heat loss coefficient by 10-15% as compared to single glass cover. The overall heat loss coefficients were also estimated analytically by parallel plate correlation and cavity correlations. The trend of variation of estimated heat loss coefficients by both methods was similar to experimental values. However, estimated values by cavity correlation were closure and uniformly distributed at all temperature range.

  17. Orientation to solar radiation in black wildebeest (Connochaetes gnou).

    Science.gov (United States)

    Maloney, Shane K; Moss, Graeme; Mitchell, Duncan

    2005-11-01

    We recorded the body axis orientation of free-living black wildebeest relative to incident solar radiation and wind. Observations were made on three consecutive days, on six occasions over the course of 1 year, in a treeless, predominantly cloudless habitat. Frequency of orientation parallel to incident solar radiation increased, and perpendicular to incident solar radiation decreased, as ambient dry-bulb temperature or solar radiation intensity increased, or wind speed decreased. We believe these changes were mediated via their effect on skin temperature. Parallel orientation behavior was more prominent when the wildebeest were standing without feeding than it was when they were feeding. We calculate that a black wildebeest adopting parallel orientation throughout the diurnal period would absorb 30% less radiant heat than the same animal adopting perpendicular orientation. Parallel orientation was reduced at times when water was freely available, possibly reflecting a shift from behavioral to autonomic thermoregulatory mechanisms. The use of orientation behavior by black wildebeest is well developed and forms part of the suite of adaptations that help them to maintain heat balance while living in a shadeless, often hot, environment. PMID:16075268

  18. The Physicochemical Changes of Black Garlic during Thermal Processing

    OpenAIRE

    Mengmeng Lei; Zesheng Zhang; Rui Liu; Min Zhang; Mengying Xu

    2015-01-01

    To explore the physicochemical changes of black garlic during the thermal processing steps and further reveal the role of Maillard reaction in the formation mechanism of black garlic. The physicochemical changes including UV-Vis absorbance, fluorescence and color difference were determined. The UV absorbance at 294 nm and browning intensity at 420 nm gradually increased with increasing heating time, while the fluorescence intensity showed a maximum value at the heating time of 3 days. The col...

  19. Liquid metal reactor absorber technology

    International Nuclear Information System (INIS)

    This paper reports that the selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth, compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts

  20. Liquid metal reactor absorber technology

    International Nuclear Information System (INIS)

    The selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts. 3 refs., 3 figs

  1. Novel active vibration absorber with magnetorheological fluid

    Science.gov (United States)

    Gerlach, T.; Ehrlich, J.; Böse, H.

    2009-02-01

    Disturbing vibrations diminish the performance of technical high precision devices significantly. In search of a suitable solution for reducing these vibrations, a novel concept of active vibration reduction was developed which exploits the special properties of magnetorheological fluids. In order to evaluate the concept of such an active vibration absorber (AVA) a demonstrator was designed and manufactured. This demonstrator generates a force which counteracts the motion of the vibrating body. Since the counterforce is generated by a centrifugal exciter, the AVA provides the capability to compensate vibrations even in two dimensions. To control the strength of the force transmitted to the vibrating body, the exciter is based on a tunable MR coupling. The AVA was integrated in an appropriate testing device to investigate its performance. The recorded results show a significant reduction of the vibration amplitudes by an order of magnitude.

  2. Black Culture

    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. 

  3. Absorber pin development in Europe

    International Nuclear Information System (INIS)

    The neutron absorbing material chosen for the absorber elements of the European fast reactor (EFR) is boron carbide. Various pin designs are studied in Europe: (1) vented helium-bonded pins chosen for prototype fast reactor (PFR) control rods, (2) vented sodium-bonded pins chosen for the Phenix and Superphenix control rods, (3) vented shrouded sodium-bonded pins chosen for future loads of Superphenix control ros. There are three aspects to the research and development program to evaluate absorber pin performance: (1) experimental irradiation program dealing with basic studies and validation design experiments, (2) modeling of B4C physical properties, descriptive laws, and code development, (3) design optimization and innovative studies (various B4C enrichments and pellet densities, new absorber materials). The irradiation program is being performed in Phenix and PFR using either control rods or static rigs

  4. Hyperuniformity of Critical Absorbing States

    Science.gov (United States)

    Hexner, Daniel; Levine, Dov

    2015-03-01

    The properties of the absorbing states of nonequilibrium models belonging to the conserved directed percolation universality class are studied. We find that, at the critical point, the absorbing states are hyperuniform, exhibiting anomalously small density fluctuations. The exponent characterizing the fluctuations is measured numerically, a scaling relation to other known exponents is suggested, and a new correlation length relating to this ordering is proposed. These results may have relevance to photonic band-gap materials.

  5. The absorber hypothesis of electrodynamics

    OpenAIRE

    De Luca, Jayme

    2008-01-01

    We test the absorber hypothesis of the action-at-a-distance electrodynamics for globally-bounded solutions of a finite-particle universe. We find that the absorber hypothesis forbids globally-bounded motions for a universe containing only two charged particles, otherwise the condition alone does not forbid globally-bounded motions. We discuss the implication of our results for the various forms of electrodynamics of point charges.

  6. Educação, identidade negra e formação de professores/as: um olhar sobre o corpo negro e o cabelo crespo Education, black identity, and teacher education: a look upon the black body and hair

    Directory of Open Access Journals (Sweden)

    Nilma Lino Gomes

    2003-06-01

    aesthetics. For that, the text introduces the need to articulate education and non-education processes, to insert new themes and discussions into the field of teacher education. Following on the considerations made by the author in her doctoral thesis, the representations and notions about the black body and hair constructed inside and outside school are discussed, based on memories and testimonies of black men and women interviewed during an ethnographic study carried out in ethnic beauty shops in Belo Horizonte. For those people, the experience with the black body and hair is not restricted to the family environment, friendships, militancy or love life. The school appears in several testimonies as an important space in which the tense process of construction of the black identity also takes place. Sadly, the school is not often remembered as an institution where black people and their aesthetic standards are viewed positively. The appreciation of this context reveals that the body, as a support for the construction of the black identity, still has to be taken up as a theme of choice by the educational field, particularly in the studies on teacher education and ethnic-cultural diversity. It also shows that, when considering such diversity, this field of study will have to open itself to the dialogue with other spaces where black people also construct their identity, spaces such as beauty shops, many times regarded as unconventional in the field of education.

  7. Are black holes totally black?

    CERN Document Server

    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.

  8. Cryo-Etched Black Silicon for Use as Optical Black

    Science.gov (United States)

    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.

  9. Sources of light-absorbing aerosol in arctic snow and their seasonal variation

    OpenAIRE

    Hegg, D.A.; Warren, S. G.; Grenfell, T. C.; Doherty, S. J.; A. D. Clarke

    2010-01-01

    Two data sets consisting of measurements of light absorbing aerosols (LAA) in arctic snow together with suites of other corresponding chemical constituents are presented; the first from Siberia, Greenland and near the North Pole obtained in 2008, and the second from the Canadian arctic obtained in 2009. A preliminary differentiation of the LAA into black carbon (BC) and non-BC LAA is done. Source attribution of the light absorbing aerosols was done using a positive matrix factorization (PMF) ...

  10. Black Holes and Galaxy Metamorphosis

    CERN Document Server

    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.

  11. Review Paper on Selective Coating of Absorber Tube for Parabolic Trough Collector

    Directory of Open Access Journals (Sweden)

    Mr. Ladgaonkar P.S.*1

    2014-04-01

    Full Text Available This paper describes the various coatings used for absorber tube of Parabolic Trough Collector (PTC and their properties. Solar thermal selective absorber coatings are currently characterized by their solar absorptance and their thermal emittance. Mostly coating is by electroplating, paint coatings and deposited cermet. This paper mainly focus on properties of Black chrome, Black Nickel , Black cobalt, Black-colored CuFeMnO4 spinel powder, Thickness-sensitive spectrally selective (TSSS paint coating, spray-coated graphitic films and there manufacturing process. The coatings need to be stable in air in case the vacuum is breached. Current coatings do not have the stability and performance desired for moving to higher operating temperatures.

  12. The First Massive Black Hole Seeds and Their Hosts

    OpenAIRE

    Bellovary, Jillian; Volonteri, Marta; Governato, Fabio; Shen, Sijing; Quinn, Thomas; Wadsley, James

    2011-01-01

    We investigate the formation of the first massive black holes in high redshift galaxies, with the goal of providing insights to which galaxies do or do not host massive black holes. We adopt a novel approach to forming seed black holes in galaxy halos in cosmological SPH+N-body simulations. The formation of massive black hole seeds is dictated directly by the local gas density, temperature, and metallicity, and motivated by physical models of massive black hole formation. We explore seed blac...

  13. Absorber materials in CANDU PHWRs

    International Nuclear Information System (INIS)

    In a CANDU reactor the fuel channels are arranged on a square lattice in a calandria filled with heavy water moderator. This arrangement allows five types of tubular neutron absorber devices to be located in the relatively benign environment of low pressure, low temperature heavy water between neighbouring rows or columns of fuel channels. This paper will describe the roles of the devices and outline the design requirements of the absorber component from a reactor physics viewpoint. Nuclear heating and activation problems associated with the different absorbers will be briefly discussed. The design and manufacture of the devices will be also discussed. The control rod absorbers and shut off materials are cadmium and stainless steel. In the tubular arrangement, the cadmium is sandwiched between stainless steel tubes. This type of device has functioned well, but there is now concern over the availability and expense of cadmium which is used in two types of CANDU control devices. There are also concerns about the toxicity of cadmium during the fabrication of the absorbers. These concerns are prompting AECL to study alternatives. To minimize design changes, pure boron-10 alloyed in stainless steel is a favoured option. Work is underway to confirm the suitability of the boron-loaded steel and identify other encapsulated absorber materials for practical application. Because the reactivity devices or their guide tubes span the calandria vessel, the long slender components must be sufficiently rigid to resist operational vibration and also be seismically stable. Some of these components are made of Zircaloy to minimize neutron absorption. Slow irradiation growth and creep can reduce the spring tension, and periodic adjustments to the springs are required. Experience with the control absorber devices has generally been good. In one instance liquid zone controllers had a problem of vibration induced fretting but a redesigned back-fit resolved the problem. (author). 3 refs, 8

  14. Black/White Differences in Perceived Weight and Attractiveness among Overweight Women

    OpenAIRE

    Chithambo, Taona P.; Stanley J. Huey

    2013-01-01

    Numerous studies have reported that Black women are more satisfied with their bodies than White women. The buffering hypothesis suggests that aspects of Black culture protect Black women against media ideals that promote a slender female body type; therefore, Black women are expected to exhibit higher body esteem than White women. To test this hypothesis, the current study aimed to assess the influence of race on weight perception, perceived attractiveness, and the interrelations between body...

  15. Life under a black sun

    CERN Document Server

    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.

  16. Mushroom plasmonic metamaterial infrared absorbers

    International Nuclear Information System (INIS)

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors

  17. Carbon Absorber Retrofit Equipment (CARE)

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Eric [Neumann Systems Group, Incorporated, Colorado Springs, CO (United States)

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  18. An Investigation on Optimal Designing of Dynamic Vibration Absorbers Using Genetic Algorithm

    OpenAIRE

    ABDOLLAHI KAMRAN, Mehdi; Rezazadeh, Ghader; GHAFFARI, Shiva

    2015-01-01

    Abstract. In this study reducing of the unwanted phenomenon in machine tools, Vibration, has been investigated. The machine tools has been simulated as a five-degree-of-freedom discrete system consisting of cutting tool, work piece, body, head and cantilever of the machine. In order to reduce the undesired vibrations, a dynamic vibration absorber (DVA) with three unknown parameters (mass absorber, damping coefficient , stiffness absorber has been added to the system in different positions. Ut...

  19. Light Absorbing Aerosols in Mexico City

    Science.gov (United States)

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  20. Black market

    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.)

  1. Waveform-dependent absorbing metasurfaces

    CERN Document Server

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  2. Study of an electroacoustic absorber

    OpenAIRE

    Rodríguez de Antonio, Javier

    2008-01-01

    El problema de la atenuación del ruido de baja frecuencia todavía persiste pese a que ha sido ampliamente estudiado. Las técnicas para absorber ruido de alta frecuencia (superior a 500 Hz), como son los materiales porosos, resonadores de Helmholtz o espumas no ofrecen resultados aceptables a bajas frecuencias. Serían necesarios volúmenes impracticables de materiales porosos para intentar absorber frecuencias menores a 500 Hz, y lo mismo ocurre con los resonadores de Helmholtz. Esta ineficacia...

  3. Perfectly Reflectionless Omnidirectional Electromagnetic Absorber

    CERN Document Server

    Sainath, Kamalesh

    2014-01-01

    We demonstrate the existence of metamaterial blueprints describing, and fundamental limitations concerning, perfectly reflectionless omnidirectional electromagnetic absorbers (PR-OEMA). Previous attempts to define PR-OEMA blueprints have led to active (gain), rather than passive, media. We explain this fact and unveil new, distinct limitations of true PR-OEMA devices including the appearance of an "electromagnetic horizon" on physical solutions. As practical alternatives, we introduce two new OEMA blueprints. While these two blueprints do not correspond to reflectionless media, they are effective in absorbing incident waves in a manner robust to incident wave diversity.

  4. Diffusion coefficients for absorbing materials

    International Nuclear Information System (INIS)

    A method to improve the diffusion results for systems containing strong absorbers is described. Each absorbing material is transformed into an equivalent rectangle. Transport and diffusion calculations in slab geometry are performed for both directions of the rectangle, and group-dependent diffusion coefficients are determined by matching the outgoing currents. Test problems comprise a critical slab, a compact PWR fuel element storage pool and two BWR fuel elements with a control rod and a poison cell. The multiplication factors of these systems are calculated with an accuracy of 1 to 2%. (Auth.)

  5. Adaptive inertial shock-absorber

    Science.gov (United States)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  6. Anomalous Diffusion with Absorbing Boundary

    OpenAIRE

    Kantor, Yacov; Kardar, Mehran

    2007-01-01

    In a very long Gaussian polymer on time scales shorter that the maximal relaxation time, the mean squared distance travelled by a tagged monomer grows as ~t^{1/2}. We analyze such sub-diffusive behavior in the presence of one or two absorbing boundaries and demonstrate the differences between this process and the sub-diffusion described by the fractional Fokker-Planck equation. In particular, we show that the mean absorption time of diffuser between two absorbing boundaries is finite. Our res...

  7. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    instance, the UK's research councils have yet to put any real money behind these ideas. Black holes are best described by the general theory of relativity. However, general relativity is a classical theory of gravity, and although its predictions have been verified in many experiments, a quantum theory of gravity remains one of the holy grails of physics. One of the first physicists to make real progress in this quest to reconcile general relativity and quantum mechanics was Stephen Hawking. In 1974 Hawking calculated what would happen if a quantum fluctuation occurred near an event horizon. He concluded that the black hole would radiate, and that the amount of radiation would be inversely proportional to the mass of the black hole. However, black holes tend to be very heavy, so their output of Hawking radiation would be too low to detect experimentally. One intriguing exception could be much smaller primordial black holes created in the big bang: these should radiate observable amounts of gamma rays, but they have not been detected yet. This whole body of work - in which thermodynamic concepts such as temperature and entropy are also associated with the black hole - is Hawking's major achievement in physics. The detection of Hawking radiation is the ultimate goal of experiments on artificial black holes, although a lot of theoretical and experimental work has to be done first. The successful experiment is likely to involve a flowing Bose-Einstein condensate or a medium in which the speed of light can be reduced to zero. After years of groundwork, physicists have recently made rapid progress in both these fields. Meanwhile, the recent observation of neutrons in discrete quantum states in a gravitational potential shows that quantum gravity effects can be seen in the laboratory. All that is needed now is an act of faith. (U.K.)

  8. Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hader, J.; Moloney, J. V. [Nonlinear Control Strategies, Inc., 3542 N. Geronimo Ave., Tucson, Arizona 85705 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Yang, H.-J.; Scheller, M. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Koch, S. W. [Department of Physics and Materials Sciences Center, Philipps Universität Marburg, Renthof 5, 35032 Marburg (Germany)

    2016-02-07

    Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

  9. Nanoarchitecture in the black wings of Troides magellanus: a natural case of absorption enhancement in photonic materials

    CERN Document Server

    Herman, Aline; Deparis, Olivier; Simonis, Priscilla; Vigneron, Jean Pol

    2013-01-01

    The birdwings butterfly Troides magellanus possesses interesting properties for light and thermal radiation management. The black wings of the male exhibit strong (98%) absorption of visible light as well as two strong absorption peaks in the infrared both due to chitin. These peaks are located in the spectral region where the black body emits at 313K. The study of absorption enhancement in this butterfly could be helpful to design highly absorbent biomimetic materials. Observations of the wings using a scanning electron microscope (SEM) reveal that the scales covering the wings are deeply nanostructured. A periodic three-dimensional (3D) model of the scale nanoarchitecture is elaborated and used for numerical transfer-matrix simulations of the absorption spectrum. The complex refractive index of the wing material is approximated by a multi-oscillator Lorentz model, leading to a broad absorption in the visible range as well as two peaks in the infrared. The absorption peak intensities turn out to be dependent...

  10. Preview control of vehicle suspension system featuring MR shock absorber

    International Nuclear Information System (INIS)

    This paper presents control performance evaluation of optimal preview control algorithm for vehicle suspension featuring MR shock absorber. The optimal preview control algorithm has several advantages such as high control performance over that which is best for a non-preview system. In order to achieve this goal, a commercial MR shock absorber, Delphi MganerideTM, which is applicable to high class passenger vehicle, is adopted and its field-dependent damping force and dynamic responses are experimentally evaluated. Then the governing equation of motion for the full-vehicle model is established and integrated with the MR shock absorber. Subsequently, optimal controller with preview control algorithm is formulated and implemented for vibration suppression of the car body. Control performance of the preview controller is evaluated for the full-vehicle model under random road condition. In addition, the control performances depending on preview distances are evaluated.

  11. [Absorbable coronary stents. New promising technology].

    Science.gov (United States)

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    revascularization rate of 23.8% which was below the 30% cut point of the study protocol. No myocardial Q wave infarction or death were reported. The primary endpoint was reached. During the follow-up period, vasomotion was tested in some of the patients. The proof of principle was confirmed: restoration of vasomotion during acetylcholine testing. The development of the absorbable magnesium stent, which was pushed forward by B. Heublein, Hanover, Germany, has been successful and opens new possibilities for treatment of coronary arteries. Permanent foreign-body implantation is avoided allowing further revascularization procedures in the future, bypass grafting, and restoration of vasomotion. Even prophylactic stenting in nonsignificant stenosis, like vulnerable lesions, may become a regular procedure. Noninvasive coronary imaging by CT and MRI is now possible. Stenting of children and in peripheral arteries may become a standard procedure. Currently, the degradation process of the magnesium stent has to be prolonged, and the neointima proliferation rate has to be reduced so that the DREAM (Drug-Eluting Absorbable Magnesium Stent) concept of Ron Waksman, Washington, DC, USA, can be realized. PMID:17607538

  12. Shape of black holes

    CERN Document Server

    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.

  13. Black-hole astrophysics

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-07-01

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

  14. Insight into magnetorheological shock absorbers

    CERN Document Server

    Gołdasz, Janusz

    2015-01-01

    This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

  15. Optical trapping of absorbing particles

    CERN Document Server

    Rubinsztein-Dunlop, H; Friese, M E J; Heckenberg, N R

    1998-01-01

    Radiation pressure forces in a focussed laser beam can be used to trap microscopic absorbing particles against a substrate. Calculations based on momentum transfer considerations show that stable trapping occurs before the beam waist, and that trapping is more effective with doughnut beams. Such doughnut beams can transfer angular momentum leading to rotation of the trapped particles. Energy is also transferred, which can result in heating of the particles to temperatures above the boiling point of the surrounding medium.

  16. Optical trapping of absorbing particles

    OpenAIRE

    Rubinsztein-Dunlop, H.; Nieminen, T. A.; Friese, M. E. J.; Heckenberg, N R

    2003-01-01

    Radiation pressure forces in a focussed laser beam can be used to trap microscopic absorbing particles against a substrate. Calculations based on momentum transfer considerations show that stable trapping occurs before the beam waist, and that trapping is more effective with doughnut beams. Such doughnut beams can transfer angular momentum leading to rotation of the trapped particles. Energy is also transferred, which can result in heating of the particles to temperatures above the boiling po...

  17. 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)

  18. A Model For The Absorption Of Thermal Radiation By Gold-Black

    OpenAIRE

    Quinlan, Brendan Robert

    2015-01-01

    The work presented here addresses an important topic in thermal radiation detection when gold-black is used as an absorber. Sought is a model to simulate the absorption of thermal radiation by gold-black. Fractal geometry is created to simulate the topology of gold-black. Then electrical circuits based on the topology are identified that capture the physics of the interaction between the gold-black material and incident electro-magnetic radiation. Parameters of the model are then adj...

  19. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    Science.gov (United States)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2015-09-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  20. Microwave absorbing property of silicone rubber composites with added carbonyl iron particles and graphite platelet

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yonggang; Zhang, Deyuan [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Yuan, Liming; Zhang, Wenqiang [Bionic and Micro/Nano/Bio-Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2013-02-15

    Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1-18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum -11.85 dB at 1.5 mm and -15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band. - Highlights: Black-Right-Pointing-Pointer The added GP increased the permittivity and permeability of composites filled with CIPs. Black-Right-Pointing-Pointer The enhancement was owing to interactions of the two absorbents and the fabrication process. Black-Right-Pointing-Pointer The coating process decreased the effective eccentricity of the particles, and increased the conductivity of the composites. Black-Right-Pointing-Pointer The composites to which CIPs/GP were added in coating process had excellent absorbing properties in the L-band.

  1. Nonlocal Effects in Black Body Radiation

    CERN Document Server

    Bremm, G N

    2016-01-01

    Nonlocal electrodynamics is a formalism developed to include nonlocal effects in the measurement process caused by the non-inertial state of the observers. This theory modifies Maxwell's electrodynamics by eliminating the hypothesis of locality that assumes an accelerated observer simultaneously equivalent to a comoving inertial frame of reference. In this scenario, the transformation between an inertial and accelerated observer is generalized which affects the properties of physical fields. In particular, we analyze how an uniformly accelerated observer perceives a homogeneous and isotropic blackbody radiation. We show that all nonlocal effects are transient and most relevant in the first period of acceleration.

  2. Sonoluminescence Nature's Smallest BlackBody

    CERN Document Server

    Vázquez, G A; Putterman, Seth J; Weninger, K R

    2000-01-01

    The Spectrum of the light emitted by a sonoluminescing bubble is extremely well fit by the spectrum of a blackbody. Furthermore the radius of emission can be smaller than the wavelength of the light. Consequences, for theories of sonoluminescence are discussed.

  3. Fischer Black

    OpenAIRE

    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.

  4. Glueing of solar absorbers; Solarabsorber kleben

    Energy Technology Data Exchange (ETDEWEB)

    Berner, Joachim

    2012-04-20

    Bonding technologies in absorber fabrication are evolving. After soldering, ultrasonic welding and laser welding, glueing is the latest development. The Go Innovate AG company developed a process for glueing the most varied absorber materials.

  5. Reconceptualizing Successful Aging Among Black Women and the Relevance of the Strong Black Woman Archetype

    OpenAIRE

    Baker, Tamara A.; Buchanan, NiCole T.; Mingo, Chivon A.; Roker, Rosalyn; Brown, Candace S

    2014-01-01

    Although there are multiple pathways to successful aging, little is known of what it means to age successfully among black women. There is a growing body of literature suggesting that black women experience a number of social challenges (sexism and racism) that may present as barriers to aging successfully. Applying aspects of the Strong Black Women ideal, into theoretical concepts of successful aging, may be particularly relevant in understanding which factors impair or promote the ability o...

  6. Black hole entropy and the renormalization group

    CERN Document Server

    Satz, Alejandro

    2013-01-01

    Four decades after its first postulation by Bekenstein, black hole entropy remains mysterious. It has long been suggested that the entanglement entropy of quantum fields on the black hole gravitational background should represent at least an important contribution to the total Bekenstein-Hawking entropy, and that the divergences in the entanglement entropy should be absorbed in the renormalization of the gravitational couplings. In this talk, we describe how an improved understanding of black hole entropy is obtained by combining these notions with the renormalization group. By introducing an RG flow scale, we investigate whether the total entropy of the black hole can be partitioned in a "gravitational" part related to the flowing gravitational action, and a "quantum" part related to the unintegrated degrees of freedom. We describe the realization of this idea for free fields, and the complications and qualifications arising for interacting fields.

  7. Piezooptic effect of absorbing environment

    Directory of Open Access Journals (Sweden)

    Ю. А. Рудяк

    2013-07-01

    Full Text Available Application of piezooptic effect of absorbing environment for the definition of the parameter of stress deformation state was examined. The analysis of dielectric permeability tensor of imaginary parts was done. It is shown that changes in the real part dielectric permeability tensor mainly the indicator of fracture was fixed by means of mechanics interference methods and the changes in the imaginary part (α – real rate of absorption can be measured by means of analysis of light absorption and thus stress deformation state can be determined

  8. Mining the XRT archive to probe the X-ray absorber structure in the AGN population

    CERN Document Server

    Ballo, L; Moretti, A; Della Ceca, R; Andreon, S; Caccianiga, A; Braito, V; Campana, S; Vignali, C

    2015-01-01

    One of the key ingredients of the Unified Model of Active Galactic Nuclei (AGN) is the presence of a torus-like optically thick medium composed by dust and gas around the putative supermassive black hole. However, the structure, size and composition of this circumnuclear medium are still matter of debate. To this end, the search for column density variations through X-ray monitoring on different timescales (months, weeks and few days) is fundamental to constrain size, kinematics and location of the X-ray absorber(s). Here we describe our project of mining the Swift-XRT archive to assemble a sample of AGN with extreme column density variability and determining the physical properties of the X-ray absorber(s). We also present the results obtained from a daily-weekly Swift-XRT follow-up monitoring recently performed on one of the most interesting new candidates for variability discovered so far, Mrk 915.

  9. A new search for primordial black hole evaporations using the Whipple gamma-ray telescope

    OpenAIRE

    Linton, E. T.; Atkins, R. W.; Badran, H. M.; Blaylock, G.; Boyle, P J; Buckley, J. H.; Byrum, K.L.; Carter-Lewis, D. A.; Celik, O.; Chow, Y. C. K.; Cogan, P.; Daniel, M. K.; Dowdall, C.; Falcone, A. D.; Fegan, D. J.

    2006-01-01

    Stephen Hawking's prediction that black holes should radiate like black bodies has several important consequences, including the possibility of the detection of small (similar to 10(15) g) black holes created in the very early universe. The detection of such primordial black holes ( PBHs) would be an important discovery, not only confirming Hawking's theory, but also providing valuable insights into the history of...

  10. Thermal radiation absorbed by dairy cows in pasture

    Science.gov (United States)

    da Silva, Roberto Gomes; Guilhermino, Magda Maria; de Morais, Débora Andréia E. Façanha

    2010-01-01

    The goal of the present paper was to assess a method for estimating the thermal radiation absorbed by dairy cows (0.875 Holstein-0.125 Guzerath) on pasture. A field test was conducted with 472 crossbred dairy cows in three locations of a tropical region. The following environmental data were collected: air temperature, partial vapour pressure, wind speed, black globe temperature, ground surface temperature and solar radiation. Average total radiation absorbed by animals was calculated as {R_{abs}} = 640.0 ± 3.1 W.{m^{ - 2}} . Absorbed short-wave radiation (solar direct, diffuse and reflected) averaged 297.9 ± 2.7 W m-2; long wave (from the sky and from terrestrial surfaces) averaged 342.1 ± 1.5 W m-2. It was suggested that a new environmental measurement, the effective radiant heat load (ERHL), could be used to assess the effective mean radiant temperature ( {T_{mr}^* } ) . Average T_{mr}^* was 101.4 ± 1.2°C, in contrast to the usual mean radiant temperature, {T_{mr}} = 65.1 ± 0.5° C . Estimates of T_{mr}^* were considered as more reliable than those of T mr in evaluating the thermal environment in the open field, because T mr is almost totally associated only with long wave radiation.

  11. Verificação das doses de radiação absorvidas durante a técnica de irradiação de corpo inteiro nos transplantes de medula óssea, por meio de dosímetros termoluminescentes Measurement of absorbed radiation doses during whole body irradiation for bone marrow transplants using thermoluminescent dosimeters

    Directory of Open Access Journals (Sweden)

    Adelmo José Giordani

    2004-10-01

    Full Text Available OBJETIVO: Avaliar a precisão das doses de radiação absorvidas na terapia de transplantes de medula óssea durante a técnica de irradiação de corpo inteiro. MATERIAIS E MÉTODOS: Utilizaram-se 200 pastilhas de sulfato de cálcio com disprósio compactado com teflon (CaSO4 + teflon, calibradas no ar e no "phantom", selecionadas aleatoriamente e dispostas em grupos de cinco no corpo dos pacientes. As leituras dosimétricas foram efetuadas pela leitora Harshaw 4000A. Nove pacientes foram irradiados no corpo inteiro em paralelos e em opostos laterais, utilizando-se unidade de cobalto-60, modelo Alcion II, com taxa de dose de 0,80 Gy/min a 80,5 cm, {campo (10 × 10 cm²}. A dosimetria dessa unidade foi realizada com dosímetro Victoreen 500. Para a determinação da dose média em cada ponto avaliado usaram-se os fatores individuais de calibração das pastilhas no ar e no "phantom", colocando-se um "build up" de 2 mm para superficializar a dose à distância de 300 cm. RESULTADOS: Em 70% dos pacientes obteve-se variação de dose menor que 5% e em 30% dos pacientes essa variação foi inferior a 10%, quando comparados os valores medidos com aqueles calculados em cada ponto. Na cabeça ocorre absorção, em média, de 14% da dose administrada, e nos pulmões, acréscimo de 2% na dose administrada. Nos pacientes com distância látero-lateral maior que 35 cm as variações entre as doses calculadas e medidas podem chegar a 30% da dose desejada, sem o uso de filtros compensadores. CONCLUSÃO: Os valores medidos das doses absorvidas nos diversos pontos anatômicos, comparados aos valores desejados (teóricos, apresentam tolerância de ±10%, considerando-se as diferenças anatômicas existentes, quando utilizados os fatores de calibração individuais das pastilhas.OBJECTIVE: To evaluate the precision of the absorbed radiation doses in bone marrow transplant therapy during whole body irradiation. MATERIALS AND METHODS: Two-hundred CaSO4:Dy + teflon

  12. Gravitational waves from compact bodies

    CERN Document Server

    Thorne, K S

    1995-01-01

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

  13. 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

  14. Enhancement mechanism of the additional absorbent on the absorption of the absorbing composite using a type-based mixing rule

    Science.gov (United States)

    Xu, Yonggang; Yuan, Liming; Zhang, Deyuan

    2016-04-01

    A silicone rubber composite filled with carbonyl iron particles and four different carbonous materials (carbon black, graphite, carbon fiber or multi-walled carbon nanotubes) was prepared using a two-roller mixture. The complex permittivity and permeability were measured using a vector network analyzer at the frequency of 2-18 GHz. Then a type-based mixing rule based on the dielectric absorbent and magnetic absorbent was proposed to reveal the enhancing mechanism on the permittivity and permeability. The enforcement effect lies in the decreased percolation threshold and the changing pending parameter as the carbonous materials were added. The reflection loss (RL) result showed the added carbonous materials enhanced the absorption in the lower frequency range, the RL decrement value being about 2 dB at 4-5 GHz with a thickness of 1 mm. All the added carbonous materials reinforced the shielding effectiveness (SE) of the composites. The maximum increment value of the SE was about 3.23 dB at 0.5 mm and 4.65 dB at 1 mm, respectively. The added carbonous materials could be effective additives for enforcing the absorption and shielding property of the absorbers.

  15. Reconceptualizing successful aging among black women and the relevance of the strong black woman archetype.

    Science.gov (United States)

    Baker, Tamara A; Buchanan, NiCole T; Mingo, Chivon A; Roker, Rosalyn; Brown, Candace S

    2015-02-01

    Although there are multiple pathways to successful aging, little is known of what it means to age successfully among black women. There is a growing body of literature suggesting that black women experience a number of social challenges (sexism and racism) that may present as barriers to aging successfully. Applying aspects of the Strong Black Women ideal, into theoretical concepts of successful aging, may be particularly relevant in understanding which factors impair or promote the ability of black women to age successfully. The Strong Black Women archetype is a culturally salient ideal prescribing that black women render a guise of self-reliance, selflessness, and psychological, emotional, and physical strength. Although this ideal has received considerable attention in the behavioral sciences, it has been largely absent within the gerontology field. Nevertheless, understanding the dynamics of this cultural ideal may enhance our knowledge while developing an appreciation of the black woman's ability to age successfully. Rather than summarize the social, physical, and mental health literature focusing on health outcomes of black women, this conceptual review examines the Strong Black Women archetype and its application to the lived experiences of black women and contributions to current theories of successful aging. Focusing on successful aging exclusively among black women enhances our understanding of this group by considering their identity as women of color while recognizing factors that dictate their ability to age successfully. PMID:25416685

  16. KINIK, Absorber Rod Calibration Kinetics

    International Nuclear Information System (INIS)

    1 - Description of program or function: KINIK is an inverse kinetic code that solves the inverse form of the point kinetic equations using the Runge-Kutta method. An optimization procedure is involved to control the time step and to reduce the running time. Up to 24 delayed neutron groups of different types (in case of heavy water as moderator or beryllium as reflector) are considered. KINIK is commonly applied to determine reactivity worths and to calibrate absorber rods. Following a rod drop, neutron flux or power is recorded as a function of time and used as input. 2 - Method of solution: The inverse point kinetic equations are numerically solved for each time step using the Runge-Kutta method. The input data resulting from measurements are first approximated by polynomials of maximum degree 10 using a least-squares approach

  17. Why muscle is an efficient shock absorber.

    Directory of Open Access Journals (Sweden)

    Michael A Ferenczi

    Full Text Available Skeletal muscles power body movement by converting free energy of ATP hydrolysis into mechanical work. During the landing phase of running or jumping some activated skeletal muscles are subjected to stretch. Upon stretch they absorb body energy quickly and effectively thus protecting joints and bones from impact damage. This is achieved because during lengthening, skeletal muscle bears higher force and has higher instantaneous stiffness than during isometric contraction, and yet consumes very little ATP. We wish to understand how the actomyosin molecules change their structure and interaction to implement these physiologically useful mechanical and thermodynamical properties. We monitored changes in the low angle x-ray diffraction pattern of rabbit skeletal muscle fibers during ramp stretch compared to those during isometric contraction at physiological temperature using synchrotron radiation. The intensities of the off-meridional layer lines and fine interference structure of the meridional M3 myosin x-ray reflection were resolved. Mechanical and structural data show that upon stretch the fraction of actin-bound myosin heads is higher than during isometric contraction. On the other hand, the intensities of the actin layer lines are lower than during isometric contraction. Taken together, these results suggest that during stretch, a significant fraction of actin-bound heads is bound non-stereo-specifically, i.e. they are disordered azimuthally although stiff axially. As the strong or stereo-specific myosin binding to actin is necessary for actin activation of the myosin ATPase, this finding explains the low metabolic cost of energy absorption by muscle during the landing phase of locomotion.

  18. Spacetime and orbits of bumpy black holes

    Science.gov (United States)

    Vigeland, Sarah J.; Hughes, Scott A.

    2010-01-01

    Our Universe contains a great number of extremely compact and massive objects which are generally accepted to be black holes. Precise observations of orbital motion near candidate black holes have the potential to determine if they have the spacetime structure that general relativity demands. As a means of formulating measurements to test the black hole nature of these objects, Collins and Hughes introduced “bumpy black holes”: objects that are almost, but not quite, general relativity’s black holes. The spacetimes of these objects have multipoles that deviate slightly from the black hole solution, reducing to black holes when the deviation is zero. In this paper, we extend this work in two ways. First, we show how to introduce bumps which are smoother and lead to better behaved orbits than those in the original presentation. Second, we show how to make bumpy Kerr black holes—objects which reduce to the Kerr solution when the deviation goes to zero. This greatly extends the astrophysical applicability of bumpy black holes. Using Hamilton-Jacobi techniques, we show how a spacetime’s bumps are imprinted on orbital frequencies, and thus can be determined by measurements which coherently track the orbital phase of a small orbiting body. We find that in the weak field, orbits of bumpy black holes are modified exactly as expected from a Newtonian analysis of a body with a prescribed multipolar structure, reproducing well-known results from the celestial mechanics literature. The impact of bumps on strong-field orbits is many times greater than would be predicted from a Newtonian analysis, suggesting that this framework will allow observations to set robust limits on the extent to which a spacetime’s multipoles deviate from the black hole expectation.

  19. Research on Simulation and Test of the Nonlinear Responses for the Hydraulic Shock Absorber

    Institute of Scientific and Technical Information of China (English)

    张建武; 刘延庆

    2003-01-01

    Basically on the multi-body system dynamics,the virtual prototype of the hydraulic shock absorber for the bench test is developed in the ADAMS environment.Dynamic behaviors of the absorber are studied by both computer simulation and real test.Numerical predictions of dynamic responses are produced by the established virtual prototype of the absorber and compared with experimental results.It has been shown from the comparison that the vibration behaviors of the prototype with hysteretic damping characteristics are considered to be more identical with the bench test results than those of the same prototype with piecewise linear damping properties are.The current virtual prototype of the shock absorber is correct and can be a developing terrace for the optimizing design of the absorber and matching capability of the whole car.

  20. Do black-furred animals compensate for high solar absorption with smaller hairs? A test with a polymorphic squirrel species

    Directory of Open Access Journals (Sweden)

    Melanie A. FRATTO, Andrew K. DAVIS

    2011-12-01

    Full Text Available In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at a higher rate. However, experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent, or minimize heat stress, although it is not clear what properties do so. Here, we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers, which would create a lighter (in terms of weight coat or one that allows greater air flow for evaporative coo- ling. We examined museum specimens of eastern fox squirrels Sciurus niger, a species native to the United States and one that displays brown, grey or all-black pelage color, and used image analysis procedures to quantify hairs from the dorsal surface and tail. From examination of 43 specimens (19 brown, 9 black and 15 grey, and 1,720 hairs, we found no significant difference in hair lengths across color morphs, but significant differences in hair fiber widths. Black squirrels had thinner body hairs than other forms (7% thinner, but thicker tail hairs (9% thicker than the others. Given that the dorsal surface would be directly exposed to solar radiation, we interpret this to be an adaptation to prevent heat stress during the day. The thicker tail hairs may be an adaptation for nighttime thermoregulation, since squirrels sleep with their tails wrapped around their bodies. These results add to a growing literature body of the functional significance of mammalian pelage [Current Zoology 57 (6: 731–736, 2011].

  1. Do black-furred animals compensate for high solar absorption with smaller hairs? A test with a polymorphic squirrel species

    Institute of Scientific and Technical Information of China (English)

    Melanie A. FRATTO; Andrew K. DAVIS

    2011-01-01

    In polymorphic mammalian species that display multiple color forms,those with dark,or melanic pelage would be prone to overheating,especially if they live in warm climates,because their fur absorbs solar energy at a higher rate.However,experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent,or minimize heat stress,although it is not clear what properties do so.Here,we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers,which would create a lighter (in terms of weight) coat or one that allows greater air flow for evaporative cooling.We examined museum specimens of eastern fox squirrels Sciurus niger,a species native to the United States and one that displays brown,grey or all-black pelage color,and used image analysis procedures to quantify hairs from the dorsal surface and tail.From examination of 43 specimens (19 brown,9 black and 15 grey),and 1,720 hairs,we found no significant difference in hair lengths across color morphs,but significant differences in hair fiber widths.Black squirrels had thinner body hairs than other forms (7% thinner),but thicker tail hairs (9% thicker) than the others.Given that the dorsal surface would be directly exposed to solar radiation,we interpret this to be an adaptation to prevent heat stress during the day.The thicker tail hairs may be an adaptation for nighttime thermoregulation,since squirrels sleep with their tails wrapped around their bodies.These results add to a growing literature body of the functional significance of mammalian pelage [Current Zoology 57 (6):731-736,2011].

  2. Black supernovae and black holes in non-local gravity

    Science.gov (United States)

    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.

  3. Brown carbon: a significant atmospheric absorber of solar radiation?

    Directory of Open Access Journals (Sweden)

    Y. Feng

    2013-01-01

    Full Text Available Several recent observational studies have shown organic carbon aerosols to be a significant source of absorption of solar radiation. The absorbing part of organic aerosols is referred to as brown carbon. Comparisons with observations indicate that model-simulated aerosol absorption is under-estimated in global models, one of the reasons being the neglect of brown carbon. Using a global chemical transport model coupled with a radiative transfer model, we estimate for the first time the enhanced absorption of solar radiation due to "brown" carbon (BrC in a global model. When BrC is included, the simulated wavelength dependence of aerosol absorption, as measured by the Angstrom exponent increases from 0.9 to 1.2 and thus agrees better with AERONET spectral observations at 440–870 nm. The resulting absorbing aerosol optical depth increases by 3–18% at 550 nm and up to 56% at 350 nm. The global simulations suggest that BrC contributes up to +0.25 W m−2 or 19% of the absorption by anthropogenic aerosols, of which 72% is attributed to black carbon, and 9% is due to sulfate and non-absorbing organic aerosols coated on black carbon. Like black carbon, the overall forcing of BrC at the top of the atmosphere (TOA is a warming effect (+0.11 W m−2, while the effect at the surface is a reduction or dimming (−0.14 W m−2. Because of the inclusion of BrC in our model, the direct radiative effect of organic carbonaceous aerosols changes from cooling (−0.08 W m−2 to warming (+0.025 W m−2 at the TOA, on a global mean basis. Over source regions and above clouds, the absorption of BrC is more significant and thus can play an important role in photochemistry and the hydrologic cycle.

  4. Black-White Health Inequalities in Canada.

    Science.gov (United States)

    Veenstra, Gerry; Patterson, Andrew C

    2016-02-01

    Little is known about Black-White health inequalities in Canada or the applicability of competing explanations for them. To address this gap, we used nine cycles of the Canadian Community Health Survey to analyze multiple health outcomes in a sample of 3,127 Black women, 309,720 White women, 2,529 Black men and 250,511 White men. Adjusting for age, marital status, urban/rural residence and immigrant status, Black women and men were more likely than their White counterparts to report diabetes and hypertension, Black women were less likely than White women to report cancer and fair/poor mental health and Black men were less likely than White men to report heart disease. These health inequalities persisted after controlling for education, household income, smoking, physical activity and body-mass index. We conclude that high rates of diabetes and hypertension among Black Canadians may stem from experiences of racism in everyday life, low rates of heart disease and cancer among Black Canadians may reflect survival bias and low rates of fair/poor mental health among Black Canadian women represent a mental health paradox similar to the one that exists for African Americans in the United States. PMID:25894533

  5. Magnetic metal nanoparticles coated polyacrylonitrile textiles as microwave absorber

    Energy Technology Data Exchange (ETDEWEB)

    Akman, O. [Physics Department, Gebze Institute of Technology (GYTE), 41400 Gebze-Kocaeli (Turkey); Department of Physics, Sakarya University, 54100, Sakarya (Turkey); Kavas, H. [Department of Physics Engineering, Faculty of Sciences, Istanbul Medeniyet University, 34720 Istanbul (Turkey); Baykal, A., E-mail: hbaykal@fatih.edu.tr [Department of Chemistry, Fatih University, 34500, B. Cekmece-Istanbul (Turkey); Toprak, M.S. [Functional Materials Division, KTH Royal Institute of Technology, SE-16440 Stockholm (Sweden); Yildirim Beyazit University, Department of Materials Science and Engineering, Ulus-Ankara (Turkey); Coruh, Ali [Department of Physics, Sakarya University, 54100, Sakarya (Turkey); Aktas, B., E-mail: aktas@gyte.edu.tr [Physics Department, Gebze Institute of Technology (GYTE), 41400 Gebze-Kocaeli (Turkey)

    2013-02-15

    Polyacrylonitrile (PAN) textiles with 2 mm thickness are coated with magnetic nanoparticles in coating baths with Ni, Co and their alloys via an electroless metal deposition method. The crystal structure, morphology and magnetic nature of composites are investigated by X-ray Powder diffraction, Scanning Electron Microscopy, and dc magnetization measurement techniques. The frequency dependent microwave absorption measurements have been carried out in the frequency range of 12.4-18 GHz (X and P bands). Diamagnetic and ferromagnetic properties are also investigated. Finally, the microwave absorption of composites is found strongly dependent on the coating time. One absorption peak is observed between 14.3 and 15.8 GHz with an efficient absorption bandwidth of 3.3-4.1 GHz (under -20 dB reflection loss limit). The Reflection loss (RL) can be achieved between -30 and -50 dB. It was found that the RL is decreasing and absorption bandwidth is decreasing with increasing coating time. While absorption peak moves to lower frequencies in Ni coated PAN textile, it goes higher frequencies in Co coated ones. The Ni-Co alloy coated composites have fluctuating curve of absorption frequency with respect to coating time. These results encourage further development of magnetic nanoparticle coated textile absorbers for broadband applications. - Highlights: Black-Right-Pointing-Pointer Ni, Co and Ni-Co alloyed coatings on PAN were successfully prepared. Black-Right-Pointing-Pointer The incorporation of magnetic nanoparticles leads to interfacial polarization. Black-Right-Pointing-Pointer The composite prepared in Ni bath at 0.5 min leads to a wider absorption bandwidth and minimum coefficient of reflection. Black-Right-Pointing-Pointer About of -42 dB, more than 99.99% of the microwave absorption.

  6. Planar Metamaterial Absorber Based on Lumped Elements

    Institute of Scientific and Technical Information of China (English)

    GU Chao; QU Shao-Bo; PEI Zhi-Bin; ZHOU Hang; XU Zhuo; BAI Peng; PENG Wei-Dong; LIN Bao-Qin

    2010-01-01

    @@ We present the design of a planar metamaterial absorber based on lumped elements,which shows a wide-band polarization-insensitive and wide-angle strong absorption.This absorber consists of metal electric resonators,the dielectric substrate,the metal film and lumped elements.The simulated absorbances under two different loss conditions indicate that high absorbance in the absorption band is mainly due to lumped resistances.The simulated absorbances under three different load conditions indicate that the local resonance circuit(lumped resistance and capacitance)could boost up the resonance of the whole RLC circuit.The simulated voltage in lumped elements indicates that the transformation efficiency from electromagnetic energy to electric energy in the absorption band is high,and electric energy is subsequently consumed by lumped resistances.This absorber may have potential applications in many military fields.

  7. Strain- and twist-engineered optical absorption of few-layer black phosphorus

    Science.gov (United States)

    Jia, Qian; Kong, XiangHua; Qiao, JingSi; Ji, Wei

    2016-09-01

    Density functional and many-body perturbation theories calculations were carried out to investigate fundamental and optical bandgap, exciton binding energy and optical absorption property of normal and strain- and twist-engineered few-layer black phosphorus (BP). We found that the fundamental bandgaps of few layer BP can be engineered by layer stacking and in-plane strain, with linear relationships to their associated exciton binding energies. The strain-dependent optical absorption behaviors are also anisotropic that the position of the first absorption peak monotonically blue-shifts as the strain applies to either direction for incident light polarized along the armchair direction, but this is not the case for that along the zigzag direction. Given those striking properties, we proposed two prototype devices for building potentially more balanced light absorbers and light filter passes, which promotes further applications and investigations of BP in nanoelectronics and optoelectronics.

  8. Multiband Negative Permittivity Metamaterials and Absorbers

    Directory of Open Access Journals (Sweden)

    Yiran Tian

    2013-01-01

    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  9. Bone marrow and thyroid absorbed doses from mammography

    International Nuclear Information System (INIS)

    Breast dose from mammography has been estimated by various investigators, because of the established effectiveness of mammography in early screening for breast cancer and the relatively high sensitivity of the breast to radiation carcinogenesis. Nevertheless, to our knowledge, there is no available information in the literature about absorbed doses from mammography to organs other than the breast. The absorbed doses to the red bone marrow in the sternum and to the thyroid, due to scattered radiation from mammographic examinations, have been measured using a Plexiglas upper-body phantom and thermoluminescent dosemeters. Their dependence on several parameters has also been examined. It is necessary to emphasize that this work is still in progress. (author)

  10. Moebius inverse problem for distorted black holes

    International Nuclear Information System (INIS)

    Hawking ''thermal'' radiation could be a means to detect black holes of micron sizes, which may be hovering through the universe. We consider these micro-black holes to be distorted by the presence of some distribution of matter representing a convolution factor for their Hawking radiation. One may hope to determine from their Hawking signals the temperature distribution of their material shells by the inverse black body problem. In 1990, Nan-xian Chen has used a so-called modified Moebius transform to solve the inverse black body problem. We discuss and apply this technique to Hawking radiation. Some comments on supersymmetric applications of Moebius function and transform are also added. (author). 22 refs

  11. A Six-Fold Symmetric Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Humberto Fernández Álvarez

    2015-04-01

    Full Text Available A novel microwave metamaterial absorber design is introduced along with its manufacturing and characterization. Significant results considering both bandwidth and angular stability are achieved. Parametric analysis and simplified equivalent circuit are provided to give an insight on the key elements influencing the absorber performance. In addition, the constitutive parameters of the effective medium model are obtained and related to the absorber resonant behavior. Moreover, a new thinner and more flexible absorber version, preserving broad bandwidth and angular insensitive performance, is simulated, and an 8 × 8 unit-cells prototype is manufactured and measured for a limited angular margin in an anechoic chamber.

  12. Absorber rod for pebble-bed reactor

    International Nuclear Information System (INIS)

    The absorber rod that can be moved into the pebble bed from the top reflector is enclosed by a cladding tube which, if it is completely moved down, ends above the pebble bed and is open at the bottom. Through the cladding tube the absorber rod is cooled with gas. The cladding tube consists of e.g. boron steel. If the absorber rod is drawn it takes along the cladding tube which is moved into the guide tube like a telescope. The rigidity of that part of the absorber rod projecting from the pebble bed is thus guaranteed. (DG)

  13. Metamaterial absorber with random dendritic cells

    Science.gov (United States)

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  14. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel; Naik, Gururaj V.; Boltasseva, Alexandra; Guan, Jianguo; Kildishev, Alexander V.; Shalaev, Vladimir M.

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material.Renewable E......We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  15. Problems in radiation absorbed dose estimation from positron emitters

    International Nuclear Information System (INIS)

    The positron emitters commonly used in clinical imaging studies for the most part are short-lived, so that when they are distributed in the body the radiation absorbed dose is low even though most of the energy absorbed is from the positrons themselves rather than the annihilation radiation. These considerations do not apply to the administration pathway for a radiopharmaceutical where the activity may be highly concentrated for a brief period rather than distributed in the body. Thus, high local radiation absorbed doses to the vein for an intravenous administration and to the upper airways during administration by inhalation can be expected. For these geometries, beta point source functions (FPS's) have been employed to estimate the radiation absorbed dose in the present study. Physiologic measurements were done to determine other exposure parameters for intravenous administration of O-15 and Rb-82 and for administration of O-15-CO2 by continuous breathing. Using FPS's to calculate dose rates to the vein wall from O-15 and Rb-82 injected into a vein having an internal radius of 1.5 mm yielded dose rates of 0.51 and 0.46 (rad x g/μCi x h), respectively. The dose gradient in the vein wall and surrounding tissues was also determined using FPS's. Administration of O-15-CO2 by continuous breathing was also investigated. Using ultra-thin thermoluninescent dosimeters (TLD's) having the effective thickness of normal tracheal mucosa, experiments were performed in which 6 dosimeters were exposed to known concentrations of O-15 positrons in a hemicylindrical tracheal phantom having an internal radius of 0.96 cm and an effective length of 14 cm. The dose rate for these conditions was 3.4 (rads/h)/(μCi/cm3). 15 references, 7 figures, 6 tables

  16. Black Hole Entropy from Entropy of Hawking Radiation

    CERN Document Server

    Aghapour, Sajad

    2016-01-01

    We provide a simple way for calculating the entropy of a Schwarzschild black hole from the entropy of its Hawking radiation. To this end, we show that if a thermodynamic system loses its energy only through the black body radiation, its loss of entropy is always 3/4 of the entropy of the emitted radiation. This proposition enables us to relate the entropy of an evaporating black hole to the entropy of its Hawking radiation. Explicitly, by calculating the entropy of the Hawking radiation emitted in the full period of evaporation of the black hole, we find the Bekenstein-Hawking entropy of the initial black hole.

  17. Radionic nonuniform black strings

    Science.gov (United States)

    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.

  18. Device for absorbing mechanical shock

    International Nuclear Information System (INIS)

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy -absorption capability

  19. Black holes and the Universe

    International Nuclear Information System (INIS)

    The superstrong gravitational field is the protagonist of this book. This gravitation is the power that warps space and time into a funnel and generates a black hole when a cosmic body undergoes catastrophic collapse. This superstrong gravitation reigns in the Universe, controlling the motion of infinitely large masses. The book describes natural phenomena caused by superstrong gravitation but perceived as nothing short of miracles, but it also explains how these miracles are studied and understood. (author)

  20. Cassini states for black hole binaries

    OpenAIRE

    Correia, Alexandre C. M.

    2015-01-01

    Cassini states correspond to the equilibria of the spin axis of a body when its orbit is perturbed. They were initially described for planetary satellites, but the spin axes of black hole binaries also present this kind of equilibria. In previous works, Cassini states were reported as spin-orbit resonances, but actually the spin of black hole binaries is in circulation and there is no resonant motion. Here we provide a general description of the spin dynamics of black hole binary systems base...

  1. Black Molecular Adsorber Coatings for Spaceflight Applications

    Science.gov (United States)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  2. Absorbed dose evaluation by SISCODES code, kerma and fluence deviations

    International Nuclear Information System (INIS)

    Radiotherapy is a common treatment of cancer. Radiotherapy exposes the patient to a radiation field, producing ionization, and absorbed dose. A precise dose calculation and the ability to execute the irradiation on the patient are necessary in order to avoid serious injuries on the surrounding health tissue, thus, the maximum acceptable absorbed dose error from the prescribed and applied is about 5%. The doses on radiotherapy are usually calculated by superimposition experimental dose profile, namely PDP, which is experimentally measured in a water simulator. Moreover, the radiation interaction with human body tissues depends on the chemical composition and the tissue density, which means the anthropomorphism and anthropometric of the human being. This paper evaluates the deviation of calculated value of kerma, induced by human body heterogeneities. To do this job two thorax voxel models created on SISCODES (one filled with various tissues other filled with water) were applied. The result of simulations permits two different comparisons. One is the ratio between tissues kermas and water kerma. Another is the ratio between human phantom fluence, where exists radiation scatter and reflection, and water phantom fluence. The reconstructed pictures of studied regions showing the calculated ratios, and graphs of the ratios versus energy of each tissue are shown. The dose ratio deviations obtained are, in some situations, larger than the acceptable 5% point out serious miscalculation of doses for some spatial regions on the human body. (author)

  3. A Unified View of X-ray Absorbers in AGNs and XRBs with MHD Winds

    Science.gov (United States)

    Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Behar, Ehud; Contopoulos, John

    2016-01-01

    The presence of UV and X-ray absorbers (aka. warm absorbers or WAs) has been long known for decades from extensive spectroscopic studies across diverse AGN populations such as nearby Seyfert galaxies and distant quasars. Furthermore, another class of seemingly distinct type of absorbers, ultra-fast outflows or UFOs, is becoming increasingly known today. Nonetheless, a physical identification of such absorbers, such as geometrical property and physical conditions, is very elusive to date despite the recent state-of-the-art observations. We develop a coherent scenario in which the detected absorbers are driven primarily (if not exclusively) by the action of global magnetic fields originating from a black hole accretion disk. In the context of MHD disk-wind of density profile of n~1/r, it is found that the properties of the observed WAs/UFOs are successfully described assuming a characteristic SED. As a case study, we analyze PG1211+143 and GRO J1655-40 to demonstrate that our wind model can systematically unify apparently diverse absorbers in both AGNs and XRBs in terms of explaining their global behavior as well as individual spectral lines.

  4. New generation elastic neutron absorber systems for new and existing design nuclear reactors

    International Nuclear Information System (INIS)

    The proposed advanced Reactivity Control Method (RCM) is designated for control of the power field of nuclear reactor during its normal operation, start-up and normal and emergency shutdown by the uniform change of distribution of solid neutron-absorbing material concentration in the reactor core using the new spiral Elastic Reactivity Control Device (ERCD). The ERCD is the elastic absorber element implemented in form of cylindrical spiral with the variable, naturally closed, coil gap. Increase or reduction of coil gap is made by pulling or releasing the elastic spiral with the actuator drive. At each position of ERCD element the elastic properties of spiral ensure the uniform distribution of absorber material in the reactor core. Once the reactor emergency protection is triggered, the ERCD is 'inserted' in the reactor core from any of its positions by the accumulated power of elastic deformation of spiral. In this case ERCD coil gap L in the reactor core rapidly decreases, which gives fast and uniform increase of solid neutron-absorbing material concentration in the reactor core. The transparency of ERCD for thermal neutrons changes from 'gray' to 'black'. The ERCD emergency insertion time is mainly defined by the speed of elastic deformation spread along the spiral body. Generally, it is the combination of the gravity force and elastic deformation force, that ensures the 'insertion' of ERCD (decrease of coil gap) in the reactor core in case of other equipment failure (e.g., loss of power supply of actuator drive). Benefits of ERCD implementation are as follows: Flattening of power field gives higher uniformity of power distribution in the reactor core, which can be achieved even in the very beginning of the reactor campaign; Better utilization of fuel provided by higher degree of burnout; High performance emergency shutdown - fast introduction of negative reactivity into the reactor core without the axial distortion of power field by rapid and uniform change of

  5. Relationship between biologic tissue heterogeneity and absorbed dose distribution in therapy of oncologic patients with cyclotron U-120 fast neutrons

    International Nuclear Information System (INIS)

    Effect of biological tissue heterogeneity on the absorbed dose distribution of U-120 cyclotron fast neutron beam was studied by estimation and experimental method. It was found that adipose and bone tissues significantly changes the pattern of neutron absorbed dose distribution in patient body. Absorbed dose in adipose layer increase by 20% as compared to the dose in soft biological tissue. Approximation method for estimation of the absorbed dose distribution of fast neutrons in heterogeneities was proposed which could be applied in the dosimetric planning of U-120 cyclotron neutron therapy of neoplasms

  6. Percolation-type behavior in black chrome selective solar films

    International Nuclear Information System (INIS)

    The optical constants (n and k) and dc resistivity have been measured for black chrome particulate solar absorbing coatings for the purpose of defining the applicability of various inhomogeneous medium theories in the description of the black chrome optical response. It has been shown that percolation-type behavior does exist in the films and hence of the various theories, only those exhibiting percolation at the 0.3 packing fraction value determined for the black chrome films are applicable. The two valid approaches are an effective medium theory first proposed by Bruggeman and a modified Maxwell Garnett theory which includes a particle shape distribution

  7. CO2在仿生物型吸收剂和其他吸收剂中的溶解度%SOLUBILITIES OF CO2 IN BIOMIMETIC AND OTHER ABSORBENTS

    Institute of Scientific and Technical Information of China (English)

    龚刚立; 王祥云; 张志炳

    2001-01-01

    Biomimetic CO2 Absorbent is a novel solvent for CO2 removal, which is derived from the key group of respiratory enzyme in animal bodies.The solubility performance of this substance is between physical and chemical absorbents and is suitable for process conditions which physical or chemical absorbents cannot match ideally.In this paper, CO2 solubilities in several typical absorbents including pure biomimetic absorbent, mixed biomimetic absorbent, AMP solution and NMP have been measured.The results show that the pure biomimetic and mixed biomimetic absorbents have good thermodynamic performance and prospective industrial application.

  8. [Absorbed doses in dental radiology].

    Science.gov (United States)

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk. PMID:8966249

  9. Stratification in Natural Water Bodies

    DEFF Research Database (Denmark)

    Møller, Jacob Steen

    2004-01-01

    Density stratification of natural water bodies plays an important role for a number of civil engineering problems. The origin of stratification in natural water is discussed and the Black Sea, the Gulf of Katchch, and Maarmorilik Fiord in Greenland are described and used as examples. Stratificati...

  10. Structured Metal Film as Perfect Absorber

    Science.gov (United States)

    Xiong, Xiang; Jiang, Shang-Chi; Peng, Ru-Wen; Wang, Mu

    2014-03-01

    With standing U-shaped resonators, fish-spear-like resonator has been designed for the first time as the building block to assemble perfect absorbers. The samples have been fabricated with two-photon polymerization process and FTIR measurement results support the effectiveness of the perfect absorber design. In such a structure the polarization-dependent resonance occurs between the tines of the spears instead of the conventional design where the resonance occurs between the metallic layers separated by a dielectric interlayer. The incident light neither transmits nor reflects back which results in unit absorbance. The power of light is trapped between the tines of spears and finally be absorbed. The whole structure is covered with a continuous metallic layer with good thermo-conductance, which provides an excellent approach to deal with heat dissipation, is enlightening in exploring metamaterial absorbers.

  11. ANL Advanced Photon Source crotch absorber design

    International Nuclear Information System (INIS)

    The ANL 7-GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 W/mm2 at normal incidence. To accommodate this high heat load, two designs were studied: one is a V-type compound angle absorber and the other is a horizontally rotated plate absorber. For both models, thermal and structural analyses have been carried out using 3-D finite element analysis. The analysis indicates that the V-type compound angle absorber controlled the peak temperatures effectively within the given geometric constraints. Test samples made of GlidCop AL 15 (alumina dispersion strengthened copper) were evaluated with an electron beam welder. The predicted and measured temperatures were in reasonable agreement. The overall absorber design includes a perforated screen in the positron beam area of the storage ring vacuum chamber to reduce RF impedance and to provide pumping access for the high local gas load

  12. 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...

  13. Noncommutative black holes

    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

  14. Black Entrepreneurship in America.

    Science.gov (United States)

    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…

  15. Specific absorbed fraction of X-ray in tissues from human organs

    International Nuclear Information System (INIS)

    Full text: X- rays are widely used in medical imaging and radiation therapy. The user of radioisotopes must have knowledge about how radiation interacts with matter, especially with the human body, because when photons enter the medium/body, they degrade their energy and build up in the medium, giving rise to secondary radiation. Calculations of the energy absorbed in a medium include not only the contribution of the uncollided photons from the source, but must also include the contributions from collided and secondary photons. In practice, this is done by multiplying the contribution of the uncollided photons by the energy absorption buildup factor. An accurate absorbed dose calculation needs specific absorbed fraction of energy. Geometric progression (GP) fitting method has been used to compute energy absorption build-up factor of Human organs such as brain, breast, eye lens, GI track, heart, kidney, liver, lung, lymph, ovary, pancreas, testis and skeleton-femur. The computed absorption build-up factor is used to estimate specific absorbed fraction of energy. The thickness of the medium up to 10mm and with penetration depth up to 40 mean free paths considered. The dependence of specific absorbed fraction of energy on incident photon energy, penetration and the thickness of the medium have also been studied. The specific absorbed fraction of energy increases up to the Epe and then decreases. Here Epe is the energy value at which the photo electric interaction coefficients matches with Compton interaction coefficients for a given value of effective atomic number (Zeff). The variation of specific absorbed fractions with energy is due to dominance of photoelectric absorption in the lower end and dominance of pair production in the higher photon energy region. In the lower energy end photoelectric absorption is dominant photon interaction process; hence specific absorbed fractions values minimum. As the energy of incident photon increases, Compton scattering overtakes

  16. Performance Analysis of Manet Before and After Black Hole Attack

    Directory of Open Access Journals (Sweden)

    Ms.Heena Bhalla

    2012-01-01

    Full Text Available A Mobile ad-hoc network is a temporary network set up by wireless mobile computers (or nodes moving arbitrary in the places that have no network infrastructure. Due to security vulnerabilities of the routing protocols, wireless ad-hoc networks are unprotected to attacks of the malicious nodes. One of the prominent attacks is the Black Hole Attack which absorbs all data packets in the network. Since the data packets do not reach the destination node on account of this attack, data loss will occur. In this paper we simulated MANETs with and without Black Hole to study the effects of Black hole attack on network performance. Because of Black Hole Attack the average packet drop increased form 0.25% to 90.69% . The throughput of the network decreased 93.56% due to Black Hole effect.

  17. Method of absorbing UF6 from gaseous mixtures in alkamine absorbents

    International Nuclear Information System (INIS)

    A method is described for recovering UF6 from gaseous mixtures by absorption in a liquid. The liquid absorbent must have a relatively low viscosity and at least one component of the absorbent is an alkamine having less than 3 carbon atoms bonded to the amino nitrogen, less than 2 of the carbon atoms other than those bonded to the amino nitrogen are free of the hydroxy radical and precipitate the absorbed uranium from the absorbent. At least one component of the absorbent is chosen from the group consisting of ethanolamine, diethanolamine, and 3-methyl-3-amino-propane-diol-1,2

  18. FEEDBACK FROM MASS OUTFLOWS IN NEARBY ACTIVE GALACTIC NUCLEI. I. ULTRAVIOLET AND X-RAY ABSORBERS

    International Nuclear Information System (INIS)

    We present an investigation into the impact of feedback from outflowing UV and X-ray absorbers in nearby (z out) and kinetic luminosity (LKE) for each AGN, summed over all of its absorbers. These calculations make use of values (or limits) for the radial locations of the absorbers determined from variability, excited-state absorption, and other considerations. From a sample of 10 Seyfert 1 galaxies with detailed photoionization models for their absorbers, we find that 7 have sufficient constraints on the absorber locations to determine M-dotout and LKE. For the low-luminosity AGN NGC 4395, these values are low, although we do not have sufficient constraints on the X-ray absorbers to make definitive conclusions. At least five of the six Seyfert 1s with moderate bolometric luminosities (Lbol = 1043 – 1045 erg s–1) have mass outflow rates that are 10-1000 times the mass accretion rates needed to generate their observed luminosities, indicating that most of the mass outflow originates from outside the inner accretion disk. Three of these (NGC 4051, NGC 3516, and NGC 3783) have LKE in the range 0.5%-5% Lbol, which is the range typically required by feedback models for efficient self-regulation of black hole and galactic bulge growth. At least two of the other three (NGC 5548, NGC 4151, and NGC 7469) have LKE ∼> 0.1%Lbol, although these values may increase if radial locations can be determined for more of the absorbers. We conclude that the outflowing UV and X-ray absorbers in moderate-luminosity AGNs have the potential to deliver significant feedback to their environments.

  19. A Planck-like problem for quantum charged black holes

    OpenAIRE

    A. FabbriBologna U. and INFN; Navarro, D. J.; Navarro-Salas, J.

    2001-01-01

    Motivated by the parallelism existing between the puzzles of classical physics at the beginning of the XXth century and the current paradoxes in the search of a quantum theory of gravity, we give, in analogy with Planck's black body radiation problem, a solution for the exact Hawking flux of evaporating Reissner-Nordstrom black holes. Our results show that when back-reaction effects are fully taken into account the standard picture of black hole evaporation is significantly ...

  20. Massive particle radiation from Gibbons-Maeda black hole

    Institute of Scientific and Technical Information of China (English)

    Fang Heng-Zhong

    2010-01-01

    This paper investigated the massive particle radiation from Gibbous-Maeda black hole by using a semi-classical method. The calculations showed that, if the self-gravitation of the radiated particle is taken into account, the radiation spectrum deviates from exact black body spectrum and the rate of tunneling equals precisely the exponent of the difference of the black hole entropies before and after emission. The conclusion supports the viewpoint of information conservation.

  1. Nike Black Brant V high altitude dynamic instability characteristics

    Science.gov (United States)

    Montag, W. H.; Walker, L. L., Jr.

    1979-01-01

    Flight experience on the Nike Black Brant V has demonstrated the existence of plume induced flow separation over the fins and aft body of the Black Brant V motor. Modelling of the forces associated with this phenomenon as well as analysis of the resultant vehicle coning motion and its effect on the velocity vector heading are presented. A summary of Nike Black Brant V flight experience with high altitude dynamic instability is included.

  2. Estimation of Absorbed Dose in Occlusal Radiography

    International Nuclear Information System (INIS)

    The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone ) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

  3. Estimation of Absorbed Dose in Occlusal Radiography

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Young Ah; Choi, Karp Shick [Dept. of Oral Radiology, College of Dentistry, Kyungpuk National University, Daegu (Korea, Republic of); Lee, Sang Han [Dept. of Oral and Maxillofacial Surgery, College of Dentistry, Kyungpook National University, Daegu (Korea, Republic of)

    1990-02-15

    The purpose of this study was to estimate absorbed dose of each important anatomic site of phantom (RT-210 Head and Neck Section R, Humanoid Systems Co., U.S.A.) head in occlusal radiography. X-radiation dosimetry at 12 anatomic sites in maxillary anterior topography, maxillary posterior topography, mandibular anterior cross-section, mandibular posterior cross-section, mandibular anterior topographic, mandibular posterior topographic occlusal projection was performed with calcium sulfate thermoluminescent dosimeters under 70 Kvp and 15 mA, 1/4 second (8 inch cone) and 1 second (16 inch cone) exposure time. The results obtained were as follows: Skin surface produced highest absorbed dose ranged between 3264 mrad and 4073 mrad but there was little difference between projections. In maxillary anterior topographic occlusal radiography, eyeballs, maxillary sinuses, and pituitary gland sites produced higher absorbed doses than those of other sites. In maxillary posterior topographic occlusal radiography, exposed eyeball site and exposed maxillary sinus site produced high absorbed doses. In mandibular anterior cross-sectional occlusal radiography, all sites were produced relatively low absorbed dose except eyeball sites. In Mandibular posterior cross-sectional occlusal radiography, exposed eyeball site and exposed maxillary sinus site were produced relatively higher absorbed doses than other sites. In mandibular anterior topographic occlusal radiography, maxillary sinuses, submandibular glands, and thyroid gland sites produced high absorbed doses than other sites. In mandibular posterior topographic occlusal radiography, submandibular gland site of the exposed side produced high absorbed dose than other sites and eyeball site of the opposite side produced relatively high absorbed dose.

  4. On the definition of absorbed dose

    International Nuclear Information System (INIS)

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before. - Highlights: • A stringent definition of absorbed dose is given. • This requires the definition of an irradiation and a suitable probability space. • A stringent definition is important for an understanding of the concept absorbed dose

  5. Black supernovae and black holes in non-local gravity

    CERN Document Server

    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...

  6. Determination of absorbed dose in water

    International Nuclear Information System (INIS)

    This report describes the experimental work carried out for the determination of absorbed dose in water in the energy of X-rays generated at potentials of 100 kV to 250 kV. Two small cavity ionization chambers were used for this experiment. The results of these measurements were compared with the results obtained by using NPL Secondary Standard Therapy level X-ray exposure meter. The related problems of converting an exposure quantity into absorbed dose in water an absorbed dose in water have also been discussed. (Orig./A.B.)

  7. CO2 Absorbing Capacity of MEA

    OpenAIRE

    José I Huertas; Gomez, Martin D.; Nicolas Giraldo; Jessica Garzón

    2015-01-01

    We describe the use of a gas bubbler apparatus in which the gas phase is bubbled into a fixed amount of absorbent under standard conditions as a uniform procedure for determining the absorption capacity of solvents. The method was systematically applied to determine the CO2 absorbing capacity of MEA (Ac) at several aqueous MEA (β) and gas-phase CO2 concentrations. Ac approached the nominal CO2 absorbing capacity of MEA (720 g CO2/kg MEA) at very low β levels, increasing from 447.9±18.1 to 581...

  8. Graphene and Graphene Metamaterials for Terahertz Absorbers

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim;

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows...... for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present our recent experimental results on the graphene absorbers characterization....

  9. Design and application of functional absorbers

    Institute of Scientific and Technical Information of China (English)

    WANG Jiqing

    2004-01-01

    This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines.

  10. Absorbed dose by a CMOS in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Valero L, C. Y.; Guzman G, K. A.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L. C., E-mail: candy_borja@hotmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2011-10-15

    Absorbed dose by a complementary metal oxide semiconductor (CMOS) circuit as part of a pacemaker, has been estimated using Monte Carlo calculations. For a cancer patient who is a pacemaker carrier, scattered radiation could damage pacemaker CMOS circuits affecting patient's health. Absorbed dose in CMOS circuit due to scattered photons is too small and therefore is not the cause of failures in pacemakers, but neutron calculations shown an absorbed dose that could cause damage in CMOS due to neutron-hydrogen interactions. (Author)

  11. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...... states, due to conduction band onparabolicity and scattering into satellite valleys in strong THz fields. Saturable absorber parameters, such as linear and nonsaturable transmission, and saturation fluence, are extracted by fits to a classic saturable absorber model. Further, we observe THz pulse...

  12. Development and study on vacuum absorber tubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun; Zhang, Yaoming [Southeast Univ., Hohai Univ., Nanjing (China); Liu, Deyou; An, cuicui [Hohai Univ., Nanjing (China)

    2008-07-01

    A new type solar vacuum absorber tube has been developed, and the tensile tests have shown the high reliability of the joint between the metal and glass of the vacuum absorber tube; the fatigue tests have indicated that the bellows of the vacuum absorber tube as well as the interface between the metal and glass can last for as long as 20 years; the weathering tests of the sample, have lasted for an entire year, which proves that the tube design is scientifically and reasonably devised. (orig.)

  13. Fast N-body Simulations on GPUs

    CERN Document Server

    Yokota, Rio

    2011-01-01

    With the current hybridization of treecodes and FMMs, combined with auto-tuning capabilities on heterogeneous architectures, the flexibility of fast N -body methods has been greatly enhanced. These features are a requirement to developing a black- box software library for fast N-body algorithms on heterogeneous systems, which is our immediate goal.

  14. Design of a magnetorheological automotive shock absorber

    Science.gov (United States)

    Lindler, Jason E.; Dimock, Glen A.; Wereley, Norman M.

    2000-06-01

    Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, a magnetorheological (MR) automotive shock absorber was designed and fabricated at the University of Maryland. Located in the piston head, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. Between the core and flux return, two different shaped gaps meet the controllable performance requirements of a double adjustable shock. A uniform gap between the core and the flux return primarily adjusts the yield force of the shock absorber, while a non-uniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non- uniform gaps for adjustment of the yield force and post-yield damping, respectively.

  15. FFTF absorber-pin performance verification test

    International Nuclear Information System (INIS)

    The FFTF (Fast Flux Test Facility) Absorber Pin Performance Verification Test - (HA006) is an irradiation test of neutron absorber pins with integral temperature and pressure monitoring instrumentation. The pins, containing boron carbide, are representative of the FFTF Row 3 Safety, Row 5 Control and Row 7 Fixed Shim Absorber Assemblies. In the 300 full power days (FPD) this test will reside in its 2610 Position in the reactor, it will generate test data that will be used to infer the effects of irradiation on the absorber assemblies it simulates. Design and fabrication of the test vehicle began in 1976 and the forty-foot test assembly was loaded in the FFTF on February 10, 1981. The test provided data in March 1981 during a series of natural circulation tests, and again in November 1981 during the eight-day full power run establishing base-line data

  16. Optically Modulated Multiband Terahertz Perfect Absorber

    DEFF Research Database (Denmark)

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue;

    2014-01-01

    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented...

  17. Absorbing boundary conditions for linear gravity waves

    OpenAIRE

    Dgaygui, Kebir; Joly, Patrick

    1992-01-01

    In this article, we construct, analyze and implement a family of absorbing boundary conditions for linear gravity waves in dimension 2. The main difficulty consists in taking into account the dispersive nature of these waves.

  18. Mucool Hydrogen Absorber R and D

    International Nuclear Information System (INIS)

    The Mucool hydrogen absorber program will be presented. An update of current projects will be described, and the next year's plan will be reviewed, along with efforts in collaboration with the Muon International Cooling Experiment

  19. Tuned mass absorber on a flexible structure

    DEFF Research Database (Denmark)

    Krenk, Steen; Høgsberg, Jan Becker

    2014-01-01

    The classic design of a tuned mass absorber is based on a simple two-mass analogy in which the tuned mass is connected to the structural mass with a spring and a viscous damper. In a flexible multi-degree-of-freedom structure the tuned mass absorber is typically introduced to provide damping of a...... specific mode. The motion of the point of attachment of the tuned mass absorber to the structure has not only a contribution from the targeted mode, but also a background contribution from other non-resonant modes. Similarly, the force provided by the tuned mass absorber is distributed between the targeted...... mode and the background modes. It is demonstrated how this effect can be included via a non-dimensional dynamic background flexibility coefficient, extracted from a classic modal analysis for the particular frequency of the selected mode. An explicit calibration procedure is developed starting with the...

  20. Study on buffering characteristics of hydraulic absorber

    International Nuclear Information System (INIS)

    Control rod hydraulic drive mechanism (CRHDM) is a new type of in-vessel control rod drive technology. Hydraulic absorber is one of the key parts of control rod hydraulic drive line. It is used to buffer control rod when the rod scrams to prevent the cross-blades of control rod from deformation and damage. Based on the working process of the hydraulic absorber, a theoretical model of the buffering process was established. Calculation results of the theoretical model agree well with the experiment results. The trend of pressure change in absorber cylinder, the displacement and velocity of the piston and buffering force during the buffering process were obtained from the calculation results of the theoretical model. Then influence parameters about cushioning characteristics were analyzed, which laid foundation for optimal design of the hydraulic absorber. (authors)

  1. Perfectly matched layer based multilayer absorbers

    Science.gov (United States)

    Stefaniuk, Tomasz; Stolarek, Marcin; Pastuszczak, Anna; Wróbel, Piotr; Wieciech, Bartosz; Antosiewicz, Tomasz J.; Kotyński, Rafał

    2015-05-01

    Broadband layered absorbers are analysed theoretically and experimentally. A genetic algorithm is used to opti- mize broadband and wide-angle of incidence metal-dielectric layered absorbers. An approximate representation of the perfectly matched layer with a spatially varied absorption strength is discussed. The PML is realised as a stack of uniform and isotropic metamaterial layers with permittivieties and permeabilities given from the effective medium theory. This approximate representation of PML is based on the effective medium theory and we call it an effective medium PML (EM-PML).1 We compare the re ection properties of the layered absorbers to that of a PML material and demonstrate that after neglecting gain and magnetic properties, the absorber remains functional.

  2. An ultra-broadband multilayered graphene absorber

    KAUST Repository

    Amin, Muhammad

    2013-01-01

    An ultra-broadband multilayered graphene absorber operating at terahertz (THz) frequencies is proposed. The absorber design makes use of three mechanisms: (i) The graphene layers are asymmetrically patterned to support higher order surface plasmon modes that destructively interfere with the dipolar mode and generate electromagnetically induced absorption. (ii) The patterned graphene layers biased at different gate voltages backedup with dielectric substrates are stacked on top of each other. The resulting absorber is polarization dependent but has an ultra-broadband of operation. (iii) Graphene\\'s damping factor is increased by lowering its electron mobility to 1000cm 2=Vs. Indeed, numerical experiments demonstrate that with only three layers, bandwidth of 90% absorption can be extended upto 7THz, which is drastically larger than only few THz of bandwidth that can be achieved with existing metallic/graphene absorbers. © 2013 Optical Society of America.

  3. Space Compatible Radar Absorbing Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase 1 project shall investigate novel radar absorbing materials (RAM) for use in space or simulated space environments. These materials are lightweight...

  4. Actual behaviour of a ball vibration absorber

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš

    2002-01-01

    Roč. 90, č. 8 (2002), s. 987-1005. ISSN 0167-6105 R&D Projects: GA ČR(CZ) GV103/96/K034 Institutional support: RVO:68378297 Keywords : TV towers * wind-excited vibrations * vibration absorbers * pendulum absorber Subject RIV: JM - Building Engineering Impact factor: 0.513, year: 2002 http://www.sciencedirect.com/science/article/pii/S0167610502002155#

  5. Semiconductor saturable absorbers for ultrafast THz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths.......We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

  6. Directed percolation with an absorbing boundary

    OpenAIRE

    Lauritsen, K. B.; K. Sneppen; Markosova, M.; Jensen, M. H.

    1997-01-01

    We consider directed percolation with an absorbing boundary in 1+1 and 2+1 dimensions. The distribution of cluster lifetimes and sizes depend on the boundary. The new scaling exponents can be related to the exponents characterizing standard directed percolation in 1+1 dimension. In addition, we investigate the backbone cluster and red bonds, and calculate the distribution of living sites along the absorbing boundary.

  7. Motor simulation of a shock absorber

    OpenAIRE

    Clancy, Brian

    1996-01-01

    The use of modern control theory to produce an electrical motor simulation of a Formula 1, Grand Pnx, passive motorcycle front suspension shock absorber is investigated. It is shown, using a test-rig comprising two permanent magnet DC motors directly coupled, that desired shock absorber responses to load forces can be achieved using model reference control. The controller feedback in this test rig is provided via a high resolution rotary position sensor. A stochastic Kalman filter is used to ...

  8. Graphene and Graphene Metamaterials for Terahertz Absorbers

    OpenAIRE

    Andryieuski, Andrei; Pizzocchero, Filippo; Booth, Tim; BØGGILD, Peter

    2013-01-01

    Graphene, due to the possibility to tune its conductivity, is the promising material for a range of the terahertz (THz) applications, such as tunable reflectors, absorbers, modulators, filters and polarization converters. Subwavelength structuring of graphene in order to form metamaterials allows for even more control over the THz waves. In this poster presentation I will show an elegant way to describe the graphene metamaterials and the design of graphene based absorbers. I will also present...

  9. Are Ethnic and Gender Specific Equations Needed to Derive Fat Free Mass from Bioelectrical Impedance in Children of South Asian, Black African-Caribbean and White European Origin? Results of the Assessment of Body Composition in Children Study

    OpenAIRE

    Nightingale, Claire M; Rudnicka, Alicja R; Owen, Christopher G; Donin, Angela S.; Newton, Sian L.; Furness, Cheryl A.; Emma L Howard; Gillings, Rachel D.; Jonathan C K Wells; Cook, Derek G.; Whincup, Peter H.

    2013-01-01

    BACKGROUND: Bioelectrical impedance analysis (BIA) is a potentially valuable method for assessing lean mass and body fat levels in children from different ethnic groups. We examined the need for ethnic- and gender-specific equations for estimating fat free mass (FFM) from BIA in children from different ethnic groups and examined their effects on the assessment of ethnic differences in body fat. METHODS: Cross-sectional study of children aged 8-10 years in London Primary schools including 325 ...

  10. Absorbed dose in the full-mouth periapical radiography, panoramic radiography, and zonography

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ, parotid gland, bone marrow in the mandibular body, and thyroid gland during the full-mouth periapical radiography, panoramic radiography, and zonography were measured. From the zonography, the absorbed doses to the brain, the skin over the TMJ, and the parotid gland were relatively high, but the absorbed doses to the bone marrow in the mandibular body and, especially, the thyroid gland were very low. The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.

  11. On the Influence of Patient Posture on Organ and Tissue Absorbed Doses Caused by Radiodiagnostic Examinations

    International Nuclear Information System (INIS)

    Virtual human phantoms, frequently used for organ and tissue absorbed dose assessment in radiology, normally represent the human body either in standing or in supine posture. This raises the question as to whether it matters dosimetrically if the postures of the patient and of the phantom do not match. This study uses the recently developed FASH2sta (Female Adult meSH) and FASH2sup phantoms which represent female adult persons in standing and supine posture. The effect of the posture on organ and tissue absorbed doses will be studied using the EGSnrc Monte Carlo code for simulating abdominal radiographs and special attention will be directed to the influence of body mass on the results. For the exposure conditions considered here, posture-dependent absorbed dose differences by up to a factor of two were found. (author)

  12. Body Odor

    Science.gov (United States)

    ... Health Medical Conditions Nutrition & Fitness Emotional Health Body Odor Posted under Health Guides . Updated 29 October 2014. + ... guy has to deal with. What causes body odor? During puberty, your sweat glands become much more ...

  13. Body Hygiene

    Science.gov (United States)

    ... Home Diaper-Changing Steps for Childcare Settings Body Hygiene Dental Hygiene Water Fluoridation Facial Cleanliness Fish Pedicures and ... spread of hygiene-related diseases . Topics for Body Hygiene Facial Cleanliness Dental Hygiene Water Fluoridation Fish Pedicures and Fish Spas ...

  14. Body Image

    Science.gov (United States)

    ... Help your child have a healthy body image Cosmetic surgery Breast surgery Botox Liposuction Varicose or spider veins Body dysmorphic disorder (BDD) Eating disorders Anorexia nervosa Binge eating ... nervosa Cosmetics and your health Depression during and after pregnancy ...

  15. Body Basics

    Science.gov (United States)

    ... about how the body works, what basic human anatomy is, and what happens when parts of the body don't function properly. Blood Bones, Muscles, and Joints Brain and Nervous System Digestive System Endocrine System Eyes Female Reproductive System ...

  16. Adaptive Piezoelectric Absorber for Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Sven Herold

    2016-02-01

    Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

  17. Superconducting Cosmic Strings that Connected a Charged Black Hole and Considered as Hair of Black Hole

    OpenAIRE

    Akcay, Ali Riza

    1999-01-01

    This paper describes that the superconducting cosmic strings can be connected to an electrically charged black hole, and can be considerd as the hair of black hole. What the no-hair theorems show is that a large amount of information is lost when a body collapses to form a black hole. In addition, the no-hair theorem has not been proved for the Yang-Mills field. This paper proves and claims that the superconducting cosmic strings can be connected to an electrically charged hole when the curre...

  18. Constructing black hole entropy from gravitational collapse

    OpenAIRE

    Acquaviva, Giovanni; Ellis, George F. R.; Goswami, Rituparno; Hamid, Aymen I. M.

    2016-01-01

    Based on a recent proposal for the gravitational entropy of free gravitational fields, we investigate the thermodynamic properties of black hole formation through gravitational collapse in the framework of the semitetrad 1+1+2 covariant formalism. In the simplest case of an Oppenheimer-Snyder-Datt collapse we prove that the change in gravitational entropy outside a collapsing body is related to the variation of the surface area of the body itself, even before the formation of horizons. As a r...

  19. Body embellishment

    OpenAIRE

    Zellweger, Christoph

    2015-01-01

    The exhibition Body Embellishment explores the most innovative artistic expression in the 21st-century international arenas of body extension, augmentation, and modification, focusing on jewelry, tattoos, nail arts, and fashion. The areas of focus are jewelry, tattoos, nail arts, and fashion. Avant-garde jewelry consciously engages the body by intersecting and expanding the planes of the human form. Tattoos are at once on and in the body. Nail art, from manicures to pedicures, has humble ...

  20. Body Clock

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2000-01-01

    Body clocks” are biological methods of controling body activities.Every living thing has one. In humans, a body clock controls normal periods of sleeping and waking. It controls the time swhen you are most likely to feel pain.Eating, sleeping and exercising at about the same time each day will help keep body activities normal. But changes in your life, a new job, for example, destroy the balance and thus cause health problems.

  1. Unmasking the Inequitable Discipline Experiences of Urban Black Girls: Implications for Urban Educational Stakeholders

    Science.gov (United States)

    Blake, Jamilia J.; Butler, Bettie Ray; Lewis, Chance W.; Darensbourg, Alicia

    2011-01-01

    There is a large body of research examining the discipline experiences of Black males (Lewis et al. in "Souls: A Critical Journey of Black Politics, Culture, and Society," 2009; Skiba et al. in "The Urban Review," 34, 317-348, 2002); however, less is known about the types of behavioral infractions Black female students exhibit and the discipline…

  2. Teaching and Learning Color Consciousness in Black Families: Exploring Family Processes and Women's Experiences with Colorism

    Science.gov (United States)

    Wilder, JeffriAnne; Cain, Colleen

    2011-01-01

    Family is regarded as a powerful force in the lives of Black Americans. Often-times, families function as an agent of socialization that counters racism. At the same time, however, Black families can perpetuate skin tone consciousness and bias, or "colorism." Although there is an extensive body of revisionist literature on Black families and a…

  3. On the definition of absorbed dose

    Science.gov (United States)

    Grusell, Erik

    2015-02-01

    Purpose: The quantity absorbed dose is used extensively in all areas concerning the interaction of ionizing radiation with biological organisms, as well as with matter in general. The most recent and authoritative definition of absorbed dose is given by the International Commission on Radiation Units and Measurements (ICRU) in ICRU Report 85. However, that definition is incomplete. The purpose of the present work is to give a rigorous definition of absorbed dose. Methods: Absorbed dose is defined in terms of the random variable specific energy imparted. A random variable is a mathematical function, and it cannot be defined without specifying its domain of definition which is a probability space. This is not done in report 85 by the ICRU, mentioned above. Results: In the present work a definition of a suitable probability space is given, so that a rigorous definition of absorbed dose is possible. This necessarily includes the specification of the experiment which the probability space describes. In this case this is an irradiation, which is specified by the initial particles released and by the material objects which can interact with the radiation. Some consequences are discussed. Specific energy imparted is defined for a volume, and the definition of absorbed dose as a point function involves the specific energy imparted for a small mass contained in a volume surrounding the point. A possible more precise definition of this volume is suggested and discussed. Conclusions: The importance of absorbed dose motivates a proper definition, and one is given in the present work. No rigorous definition has been presented before.

  4. The Black Studies Boondoggle

    Science.gov (United States)

    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)

  5. Casimir force on amplifying bodies

    OpenAIRE

    Sambale, Agnes; Welsch, Dirk-Gunnar; Buhmann, Stefan Yoshi; Dung, Ho Trung

    2009-01-01

    Based on a unified approach to macroscopic QED that allows for the inclusion of amplification in a limited space and frequency range, we study the Casimir force as a Lorentz force on an arbitrary partially amplifying system of linearly locally responding (isotropic) magnetoelectric bodies. We demonstrate that the force on a weakly polarisable/magnetisable amplifying object in the presence of a purely absorbing environment can be expressed as a sum over the Casimir--Polder forces on the excite...

  6. Black/White Differences in Perceived Weight and Attractiveness among Overweight Women

    Directory of Open Access Journals (Sweden)

    Taona P. Chithambo

    2013-01-01

    Full Text Available Numerous studies have reported that Black women are more satisfied with their bodies than White women. The buffering hypothesis suggests that aspects of Black culture protect Black women against media ideals that promote a slender female body type; therefore, Black women are expected to exhibit higher body esteem than White women. To test this hypothesis, the current study aimed to assess the influence of race on weight perception, perceived attractiveness, and the interrelations between body mass index (BMI and perceived attractiveness among overweight and obese women. Participants were 1,694 respondents of Wave IV of the National Longitudinal Study on Adolescent Health ( years. Black ( or White ( obese or overweight women were included in the current study. As expected, Black women reported lower perceived weight and higher attractiveness than White women, despite higher body mass for Black women. Furthermore, race moderated the relationship between BMI and perceived attractiveness; for White women, a negative relationship existed between BMI and attractiveness, whereas for Black women, BMI and attractiveness were not related. The study findings provide further support for the buffering hypothesis, indicating that despite higher body mass, overweight Black women are less susceptible to thin body ideals than White women.

  7. Dynamics of black holes

    OpenAIRE

    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...

  8. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-11-15

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

  9. Black Hole Statistics

    OpenAIRE

    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...

  10. Phantom Black Holes

    OpenAIRE

    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. ...

  11. Effect of the secondary organic aerosol coatings on black carbon water uptake, cloud condensation nuclei activity, and particle collapse

    Science.gov (United States)

    The ability of black carbon aerosols to absorb water and act as a cloud condensation nuclei (CCN) directly controls their lifetime in the atmosphere as well as their impact on cloud formation, thus impacting the earth’s climate. Black carbon emitted from most combustion pro...

  12. Theoretical reevaluations of black hole mass -- bulge mass relation - I. Influences of the seed black hole mass

    OpenAIRE

    Shirakata, Hikari; Kawaguchi, Toshihiro; Okamoto, Takashi; Makiya, Ryu; Ishiyama, Tomoaki; Matsuoka, Yoshiki; Nagashima, Masahiro; Enoki, Motohiro; Oogi, Taira; Kobayashi, Masakazu A. R.

    2016-01-01

    We show influences of the mass of seed black holes on black hole mass -- bulge mass relation at z ~ 0 by using a semi-analytic model of galaxy formation combined with large cosmological N-body simulations. We constrain our model to reproduce observed properties of galaxies at z ~ 0. Similar to other semi-analytic models, we place a seed black hole immediately after a galaxy forms. When we set the seed black hole mass to 10^5 M_sun, we find that the model result becomes inconsistent with recen...

  13. ANL Advanced Photon Source crotch absorber design

    International Nuclear Information System (INIS)

    The ANL 7-GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 W/mm2 at normal incidence. To accommodate this high heat load, two designs were studied: one is a V-type compound angle absorber and the other is a horizontally rotated plate absorber. For both models, thermal and structural analyses have been carried out using 3-D finite element analysis. The analysis indicates that the V-type compound angle absorber controlled the peak temperatures effectively within the given geometric constraints. Test samples made of GlidCop Al 15 (alumina dispersion strengthened copper) were evaluated with an electron beam welder. The predicted and measured temperatures were in reasonable agreement. The overall absorber design includes a perforated screen in the positron beam area of the storage ring vacuum chamber to reduce rf impedance and to provide pumping access for the high local gas load. 3 refs., 4 figs., 2 tabs

  14. Black Nuns as Educators.

    Science.gov (United States)

    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)

  15. Black Holes in Higher Dimensions (Black Strings and Black Rings)

    CERN Document Server

    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.

  16. Sassin' through Sadhana: Learned Leadership Journeys of Black Women in Holistic Practice

    Science.gov (United States)

    Panton, Rachel

    2012-01-01

    Women of color, especially Black women, are underrepresented in the extant literature and research of adult development and mind, body, spirit leadership. This in-depth qualitative portraiture study explored the lives of three Black women who have been leading their communities as adult educators of mind, body, spirit practices. This examination…

  17. Absorber Materials at Room and Cryogenic Temperatures

    International Nuclear Information System (INIS)

    We recently reported on investigations of RF absorber materials at cryogenic temperatures conducted at Jefferson Laboratory (JLab). The work was initiated to find a replacement material for the 2 Kelvin low power waveguide Higher Order Mode (HOM) absorbers employed within the original cavity cryomodules of the Continuous Electron Beam Accelerator Facility (CEBAF). This effort eventually led to suitable candidates as reported in this paper. Furthermore, though constrained by small funds for labor and resources, we have analyzed a variety of lossy ceramic materials, several of which could be usable as HOM absorbers for both normal conducting and superconducting RF structures, e.g. as loads in cavity waveguides and beam tubes either at room or cryogenic temperatures and, depending on cooling measures, low to high operational power levels.

  18. A Dynamic Absorber With Active Vibration Control

    Science.gov (United States)

    Huang, S.-J.; Lian, R.-J.

    1994-12-01

    The design and construction of a dynamic absorber incorporating active vibration control is described. The absorber is a two-degrees-of-freedom spring — lumped mass system sliding on a guide pillar, with two internal vibration disturbance sources. Both the main mass and the secondary absorber mass are acted on by DC servo motors, respectively, to suppress the vibration amplitude. The state variable technique is used to model this dynamic system and a decoupling PID control method is used. First, the discrete time state space model is identified by using the commercial software MATLAB. Then the decoupling controller of this multi-input/multi-output system is derived from the identified model. Finally the results of some experiments are presented. The experimental results show that the system is effective in suppressing vibration. Also, the performance of this control strategy for position tracking control is evaluated based on experimental data.

  19. Ferrite HOM Absorber for the RHIC ERL

    Energy Technology Data Exchange (ETDEWEB)

    Hahn,H.; Choi, E.M.; Hammons, L.

    2008-10-01

    A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurements of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.

  20. Tribology Aspect of Rubber Shock Absorbers Development

    Directory of Open Access Journals (Sweden)

    M. Banić

    2013-09-01

    Full Text Available Rubber is a very flexible material with many desirable properties Which enable its broad use in engineering practice. Rubber or rubber-metal springs are widely used as anti-vibration or anti-shock components in technical systems. Rubber-metal springs are usually realized as a bonded assembly, however especially in shock absorbers, it is possible to realize free contacts between rubber and metal parts. In previous research it authors was observed that friction between rubber and metal in such case have a significant influence on the damping characteristics of shock absorber. This paper analyzes the development process of rubber or rubber-metal shock absorbers realized free contacts between the constitutive parts, starting from the design, construction, testing and operation, with special emphasis on the development of rubber-metal springs for the buffing and draw gear of railway vehicles.

  1. Broadband plasmonic absorber for photonic integrated circuits

    CERN Document Server

    Xiong, Xiao; Ren, Xi-Feng; Guo, Guang-Can

    2013-01-01

    The loss of surface plasmon polaritons has long been considered as a fatal shortcoming in information transport. Here we propose a plasmonic absorber utilizing this "shortcoming" to absorb the stray light in photonic integrated circuits (PICs). Based on adiabatic mode evolution, its performance is insensitive to incident wavelength with bandwidth larger than 300nm, and robust against surrounding environment and temperature. Besides, the use of metal enables it to be very compact and beneficial to thermal dissipation. With this 40um-long absorber, the absorption efficiency can be over 99.8% at 1550nm, with both the reflectivity and transmittance of incident light reduced to less than 0.1%. Such device may find various applications in PICs, to eliminate the residual strong pump laser or stray light.

  2. On the warm absorber in AGN outflow

    CERN Document Server

    Adhikari, T P; Sobolewska, M; Czerny, B

    2016-01-01

    Warm absorber (WA) is an ionised gas present in the line of sight to the AGN central engine. The effect of the absorber is imprinted in the absorption lines observed in X-ray spectra of AGN. In this work, we model the WA in Seyfert 1 galaxy Mrk 509 using its recently published shape of broad band spectral energy distribution (SED) as a continuum illuminating the absorber. Using the photoionization code {\\sc Titan}, recently we have shown that the absorption measure distribution (AMD) found for this object can be successfully modelled as a single slab of gas in total pressure (radiation+gas) equilibrium, contrary to the usual models of constant density multiple slabs. We discuss the transmitted spectrum that would be recorded by an observer after the radiation from the nucleus passes through the WA.

  3. Design and fabrication of magnetic shock absorber

    Directory of Open Access Journals (Sweden)

    S. Gopinath

    2014-03-01

    Full Text Available In a vehicle, shock absorber reduces the effect of travelling over rough ground, without shock absorber the vehicle would have a bouncing ride, as an energy is stored in the spring and then released to the vehicle, possibly exceeding the allow range of suspension movement [1]. Control of excessive suspension movement without shock absorption requires stiffer springs, which would intern gives a harsh ride. Shock absorber allows the use of soft springs while controlling the rate of suspension movement in response to bumps [2]. In this project a new suspension system based on magnetic power which can be used in automobile in future. The suspension system consists of magnets freely moving inside the cylinder with their same poles facing each other. Since the magnetic poles repel each other while moving closer, the up and down spring action is obtained.   Keywords: Suspension System, Magnetic Power, Magnetic Poles.

  4. Circular polarization sensitive absorbers based on graphene

    Science.gov (United States)

    Yang, Kunpeng; Wang, Min; Pu, Mingbo; Wu, Xiaoyu; Gao, Hui; Hu, Chenggang; Luo, Xiangang

    2016-01-01

    It is well known that the polarization of a linearly polarized (LP) light would rotate after passing through a single layer graphene under the bias of a perpendicular magnetostatic field. Here we show that a corresponding phase shift could be expected for circularly polarized (CP) light, which can be engineered to design the circular polarization sensitive devices. We theoretically validate that an ultrathin graphene-based absorber with the thickness about λ/76 can be obtained, which shows efficient absorption >90% within incident angles of ±80°. The angle-independent phase shift produced by the graphene is responsible for the nearly omnidirectional absorber. Furthermore, a broadband absorber in frequencies ranging from 2.343 to 5.885 THz with absorption over 90% is designed by engineering the dispersion of graphene. PMID:27034257

  5. A Novel Burnable Absorber Concept for PWR: BigT (Burnable Absorber-Integrated Guide Thimble)

    International Nuclear Information System (INIS)

    This paper presents the essential BigT design concepts and its lattice neutronic characteristics. Neutronic performance of a newly-proposed BA concept for PWR named BigT is investigated in this study. Preliminary lattice analyses of the BigT absorber-loaded WH 17x17 fuel assembly show a high potential of the concept as it performs relatively well in comparison with commercial burnable absorber technologies, especially in managing reactivity depletion and peaking factor. A sufficiently high control rod worth can still be obtained with the BigT absorbers in place. It is expected that with such performance and design flexibilities, any loading pattern and core management objective, including a soluble boron-free PWR, can potentially be fulfilled with the BigT absorbers. Future study involving full 3D reactor core simulations with the BigT absorbers shall hopefully verify this hypothesis. A new burnable absorber design for Pressurized Water Reactor (PWR) named 'Burnable absorber-Integrated control rod Guide Thimble' (BigT) was recently proposed. Unlike conventional burnable absorber (BA) technologies, the BigT integrates BA materials directly into the guide thimble but still allows insertion of control rod (CR). In addition, the BigT offers a variety of design flexibilities such that any loading pattern and core management objective can potentially be fulfilled

  6. A Novel Burnable Absorber Concept for PWR: BigT (Burnable Absorber-Integrated Guide Thimble)

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Mohdsyukri; Kim, Yonghee [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Chung, Chang Kyu [KEPCO Engineering and Construction Company, Daejeon (Korea, Republic of)

    2014-05-15

    This paper presents the essential BigT design concepts and its lattice neutronic characteristics. Neutronic performance of a newly-proposed BA concept for PWR named BigT is investigated in this study. Preliminary lattice analyses of the BigT absorber-loaded WH 17x17 fuel assembly show a high potential of the concept as it performs relatively well in comparison with commercial burnable absorber technologies, especially in managing reactivity depletion and peaking factor. A sufficiently high control rod worth can still be obtained with the BigT absorbers in place. It is expected that with such performance and design flexibilities, any loading pattern and core management objective, including a soluble boron-free PWR, can potentially be fulfilled with the BigT absorbers. Future study involving full 3D reactor core simulations with the BigT absorbers shall hopefully verify this hypothesis. A new burnable absorber design for Pressurized Water Reactor (PWR) named 'Burnable absorber-Integrated control rod Guide Thimble' (BigT) was recently proposed. Unlike conventional burnable absorber (BA) technologies, the BigT integrates BA materials directly into the guide thimble but still allows insertion of control rod (CR). In addition, the BigT offers a variety of design flexibilities such that any loading pattern and core management objective can potentially be fulfilled.

  7. Impacts of Snow Darkening by Absorbing Aerosols on Eurasian Climate

    Science.gov (United States)

    Kim, Kyu-Myong; Lau, William K M.; Yasunari, Teppei J.; Kim, Maeng-Ki; Koster, Randal D.

    2016-01-01

    The deposition of absorbing aerosols on snow surfaces reduces snow-albedo and allows snowpack to absorb more sunlight. This so-called snow darkening effect (SDE) accelerates snow melting and leads to surface warming in spring. To examine the impact of SDE on weather and climate during late spring and early summer, two sets of NASA GEOS-5 model simulations with and without SDE are conducted. Results show that SDE-induced surface heating is particularly pronounced in Eurasian regions where significant depositions of dust transported from the North African deserts, and black carbon from biomass burning from Asia and Europe occur. In these regions, the surface heating due to SDE increases surface skin temperature by 3-6 degrees Kelvin near the snowline in spring. Surface energy budget analysis indicates that SDE-induced excess heating is associated with a large increase in surface evaporation, subsequently leading to a significant reduction in soil moisture, and increased risks of drought and heat waves in late spring to early summer. Overall, we find that rainfall deficit combined with SDE-induced dry soil in spring provide favorable condition for summertime heat waves over large regions of Eurasia. Increased frequency of summer heat waves with SDE and the region of maximum increase in heat-wave frequency are found along the snow line, providing evidence that early snowmelt by SDE may increase the risks of extreme summer heat wave. Our results suggest that climate models that do not include SDE may significantly underestimate the effect of global warming over extra-tropical continental regions.

  8. Radiation absorbed dose estimate for rubidium-82 determined from in vivo measurements in human subjects

    International Nuclear Information System (INIS)

    Radiation absorbed doses from rubidium-82 injected intravenously were determined in two young men, aged 23 and 27, using a dynamic conjugate counting technique to provide data for the net organ integrated time-activity curves in five organs: kidneys, lungs, liver, heart, and testes. This technique utilized a tungsten collimated Anger camera and the accuracy was validated in a prestwood phantom. The data for each organ were compared with conjugate count rates of a reference Ge-68/Ga-68 standard which had been calibrated against the Rb-82 injected. The effects of attenuation in the body were eliminated. The MIRD method was used to calculate the organ self absorbed doses and the total organ absorbed doses. The mean total absorbed doses were as follows (mrads/mCi injected): kidneys 30.9, heart walls 7.5, lungs 6.0, liver 3.0, testes 2.0 (one subject only), red marrow 1.3, remainder of body 1.3 and, extrapolating to women, ovaries 1.2. This absorbed dose to the kidney is significantly less than the pessimistic estimate of 59.4 mrads/mCi, made assuming instantaneous uptake and complete extraction of activity with no excretion by the kidneys, which receive 20% of the cardiac output. Further, in a 68 year old man the renal self absorbed dose was approximately 40% less than the mean renal self absorbed dose of the younger men. This decrease is probably related to the decline in renal blood flow which occurs with advancing age but other factors may also contribute to the observed difference. 14 references, 4 figures, 2 tables

  9. Evaporation of large black holes in AdS

    International Nuclear Information System (INIS)

    The AdS/CFT correspondence offers a new perspective on the long-standing black hole information paradox. However, to be able to use the available gauge/gravity machinery one is forced to consider so-called 'large' black holes in AdS, and these objects are thermodynamically stable - they do not evaporate. We describe a simple toy model that allows large AdS black holes to decay, by coupling the emitted radiation to an external scalar field propagating in an auxiliary space. This effectively changes the properties of the boundary of AdS, making it partly absorbing. We demonstrate that the evaporation process never ceases by explicitly presenting (a) the transmission coefficient for a wave scattering from the bulk into auxiliary space and (b) the greybody factor for a black 3-brane in an AdS background. Therefore, the model provides an interesting framework to address the information paradox using AdS/CFT techniques.

  10. Black-on-white polymer-stabilized cholesteric formulations

    Science.gov (United States)

    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.

  11. Source attribution of black carbon in Arctic snow.

    Science.gov (United States)

    Hegg, Dean A; Warren, Stephen G; Grenfell, Thomas C; Doherty, Sarah J; Larson, Timothy V; Clarke, Antony D

    2009-06-01

    Snow samples obtained at 36 sites in Alaska, Canada, Greenland, Russia, and the Arctic Ocean in early 2007 were analyzed for light-absorbing aerosol concentration together with a suite of associated chemical species. The light absorption data, interpreted as black carbon concentrations, and other chemical data were input into the EPA PMF 1.1 receptor model to explore the sources for black carbon in the snow. The analysis found four factors or sources: two distinct biomass burning sources, a pollution source, and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources (encompassing both open and closed combustion) together accounting for >90% of the black carbon. PMID:19569324

  12. Extremely efficient and recyclable absorbents for oily pollutants enabled by ultrathin-layered functionalization.

    Science.gov (United States)

    Wang, Qianqian; Wang, Hanghua; Xiong, Sen; Chen, Rizhi; Wang, Yong

    2014-11-12

    Oils and organic solvents that leak into water bodies must be promptly removed to avoid ecological disasters, for example, by selective absorption using oleophilic absorbents. However, it remains a challenge for the low-cost synthesis of efficient and recyclable absorbents for oily pollutants. By surface functionalization to inexpensive polyurethane (PU) foams, we synthesize oil absorbents exhibiting the highest absorption capacity and the best recyclability among all polymeric absorbents. The synthesis is enabled by atomic layer deposition of ∼5 nm-thick Al2O3 transition layer onto the skeleton surface of PU foams, followed by coupling a single-molecule layer of silanes to the Al2O3 layer. The sub-10 nm functionalization layer provides the PU foam an outstanding water-repelling and oil-absorbing functionality without compromising its high porosity and elasticity. The functionalized foam is able to quickly absorb oily pollutants spread on water surfaces or precipitated in water with a capacity more than 100 times its own weight. This ultrathin-layer-functionalization method is also applicable to renewable porous biomaterials, providing a sustainable solution for oil spills. Moreover, we propose devices than can continuously operate to efficiently collect oil spills from water surfaces based on the functionalized PU foam developed in this work. PMID:25315285

  13. 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)

  14. LINEAR MODEL FOR NON ISOSCELES ABSORBERS

    International Nuclear Information System (INIS)

    Previous analyses have assumed that wedge absorbers are triangularly shaped with equal angles for the two faces. In this case, to linear order, the energy loss depends only on the position in the direction of the face tilt, and is independent of the incoming angle. One can instead construct an absorber with entrance and exit faces facing rather general directions. In this case, the energy loss can depend on both the position and the angle of the particle in question. This paper demonstrates that and computes the effect to linear order

  15. PT-symmetric laser-absorber

    OpenAIRE

    Longhi, Stefano

    2010-01-01

    In a recent work, Y.D. Chong et al. [Phys. Rev. Lett. {\\bf 105}, 053901 (2010)] proposed the idea of a coherent perfect absorber (CPA) as the time-reversed counterpart of a laser, in which a purely incoming radiation pattern is completely absorbed by a lossy medium. The optical medium that realizes CPA is obtained by reversing the gain with absorption, and thus it generally differs from the lasing medium. Here it is shown that a laser with an optical medium that satisfies the parity-time $(\\m...

  16. The MIRD method of estimating absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Weber, D.A.

    1991-01-01

    The estimate of absorbed radiation dose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal Radiation Dose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain dose estimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimate dose from radiopharmaceuticals used in nuclear medicine.

  17. On particle creation by black holes

    International Nuclear Information System (INIS)

    Hawking's analysis of particle creation by black holes is extended by explicity obtaining the expression for the quantum mechanical state vector PSI which results from particle creation starting from the vacuum during gravitational collapse. We first discuss the quantum field theory of a Hermitian scalar field in an external potential or in a curved but asymptotically flat spacetime with no horizon present. Making the necessary modification for the case when a horizon is present, we apply this theory for a massless Hermitian scalar field to get the state vector describing the steady state emission at late times for particle creation during gravitational collapse to a Schwarzschild black hole. We find that the state vector describing particle creation from the vacuum decomposes into a simple product of state vectors for each individual mode. The density matrix describing emission of particles to infinity by this particle creation process is found to be identical to that of black body emission. Thus, black hole emission agrees in complete detail with black body emission (orig./BJ)

  18. Black Flowers in Flatland

    CERN Document Server

    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.

  19. Experimental investigation of a nanofluid absorber employed in a low-profile, concentrated solar thermal collector

    Science.gov (United States)

    Li, Qiyuan; Zheng, Cheng; Mesgari, Sara; Hewakuruppu, Yasitha L.; Hjerrild, Natasha; Crisostomo, Felipe; Morrison, Karl; Woffenden, Albert; Rosengarten, Gary; Scott, Jason A.; Taylor, Robert A.

    2015-12-01

    Recent studies [1-3] have demonstrated that nanotechnology, in the form of nanoparticles suspended in water and organic liquids, can be employed to enhance solar collection via direct volumetric absorbers. However, current nanofluid solar collector experimental studies are either relevant to low-temperature flat plate solar collectors (100 °C) indoor laboratory-scale concentrating solar collectors [1, 5]. Moreover, many of these studies involve in thermal properties of nanofluid (such as thermal conductivity) enhancement in solar collectors by using conventional selective coated steel/copper tube receivers [6], and no full-scale concentrating collector has been tested at outdoor condition by employing nanofluid absorber [2, 6]. Thus, there is a need of experimental researches to evaluate the exact performance of full-scale concentrating solar collector by employing nanofluids absorber at outdoor condition. As reported previously [7-9], a low profile (solar thermal concentrating collector was designed and analysed which can potentially supply thermal energy in the 100-250 °C range (an application currently met by gas and electricity). The present study focuses on the design and experimental investigation of a nanofluid absorber employed in this newly designed collector. The nanofluid absorber consists of glass tubes used to contain chemically functionalized multi-walled carbon nanotubes (MWCNTs) dispersed in DI water. MWCNTs (average diameter of 6-13 nm and average length of 2.5-20 μm) were functionalized by potassium persulfate as an oxidant. The nanofluids were prepared with a MCWNT concentration of 50 +/- 0.1 mg/L to form a balance between solar absorption depth and viscosity (e.g. pumping power). Moreover, experimentally comparison of the thermal efficiency between two receivers (a black chrome-coated copper tube versus a MWCNT nanofluid contained within a glass tubetube) is investigated. Thermal experimentation reveals that while the collector efficiency

  20. Body punk

    DEFF Research Database (Denmark)

    Mogensen, Kevin

    BODYPUNK - A Treatise on male body builders and the meaning of the body in the shadow of an Anti Doping Campaign Based on a qualitative study, the thesis investigates the visual representation of the male bodybuilder found in the national anti doping campaign: ‗ "The hunt has begun" along with an...... analysis of the embodied meaning of men‘s bodybuilding....

  1. Black-Hole Polarization and Cosmic Censorship

    CERN Document Server

    Hod, S

    1999-01-01

    The destruction of the black-hole event horizon is ruled out by both cosmic censorship and the generalized second law of thermodynamics. We test the consistency of this prediction in a (more) `dangerous' version of the gedanken experiment suggested by Bekenstein and Rosenzweig. A $U(1)$-charged particle is lowered {\\it slowly} into a near extremal black hole which is not endowed with a $U(1)$ gauge field. The energy delivered to the black hole can be {\\it red-shifted} by letting the assimilation point approach the black-hole horizon. At first sight, therefore, the particle is not hindered from entering the black hole and removing its horizon. However, we show that this dangerous situation is excluded by a combination of {\\it two} factors not considered in former gedanken experiments: the effect of the spacetime curvature on the electrostatic {\\it self-interaction} of the charged system (the black-hole polarization), and the {\\it finite} size of the charged body.

  2. Body Weight and Body Image

    OpenAIRE

    McFarlane Traci; Olmsted Marion P

    2004-01-01

    Abstract Health Issue Body weight is of physical and psychological importance to Canadian women; it is associated with health status, physical activity, body image, and self-esteem. Although the problems associated with overweight and obesity are indeed serious, there are also problems connected to being underweight. Weight prejudice and the dieting industry intensify body image concerns for Canadian women and can have a major negative impact on self-esteem. Key Findings Women have lower BMIs...

  3. Black holes in a box: towards the numerical evolution of black holes in AdS

    CERN Document Server

    Witek, Helvi; Herdeiro, Carlos; Nerozzi, Andrea; Sperhake, Ulrich; Zilhao, Miguel

    2010-01-01

    The evolution of black holes in "confining boxes" is interesting for a number of reasons, particularly because it mimics the global structure of Anti-de Sitter geometries. These are non-globally hyperbolic space-times and the Cauchy problem may only be well defined if the initial data is supplemented by boundary conditions at the time-like conformal boundary. Here, we explore the active role that boundary conditions play in the evolution of a bulk black hole system, by imprisoning a black hole binary in a box with mirror-like boundary conditions. We are able to follow the post-merger dynamics for up to two reflections off the boundary of the gravitational radiation produced in the merger. We estimate that about 15% of the radiation energy is absorbed by the black hole per interaction, whereas transfer of angular momentum from the radiation to the black hole is only observed in the first interaction. We discuss the possible role of superradiant scattering for this result. Unlike the studies with outgoing bound...

  4. Black, White and Grey

    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

  5. Manufacturing of Solar Absorber by Unconventional Methods

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Lidmila, Z.; Podaný, K.; Forejt, M.; Kubíček, J.

    Ostrava: TANGER Ltd, 2012. ISBN 978-80-87294-29-1. [METAL 2012. International Conference on Metallurgy and Materials /21./. Brno (CZ), 23.05.2012-25.05.2012] R&D Projects: GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : solar absorber * drawing in flexible tools * laser welding * austenitic steel Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. Measuring the absorbed radioactivity during a flight

    International Nuclear Information System (INIS)

    This paper presents the new system SIEVERT developed by the General Direction of the Civil Aviation (DGAC) to measure the radiations doses absorbed from cosmic radiation. The system is available on the Internet site: www.sievert-system.org. (A.L.B.)

  7. Technology and assessment of neutron absorbing materials

    International Nuclear Information System (INIS)

    The present review assesses more recent developments in the technology and application of those absorber materials which are considered to be established or to have shown potential in reactor control. Emphasis is placed on physical, chemical and metallurgical properties and upon irradiation behaviour. (author)

  8. Non-Absorbable Disaccharides for Hepatic Encephalopathy

    DEFF Research Database (Denmark)

    Gluud, Lise L; Vilstrup, Hendrik; Morgan, Marsha Y

    2016-01-01

    Non-absorbable disaccharides (NADs) have been used to treat hepatic encephalopathy (HE) since 1966. However, a Cochrane review, published in 2004, found insufficient evidence to recommend their use in this context. This updated systematic review evaluates the effects of the NADs, lactulose and...

  9. Timing the warm absorber in NGC 4051

    CERN Document Server

    Silva, Catia; Costantini, Elisa

    2016-01-01

    We investigated, using spectral-timing analysis, the characterization of highly ionized outflows in Seyfert galaxies, the so-called warm absorbers. Here, we present our results on the extensive ~ 600 ks of XMM-Newton archival observations of the bright and highly variable Seyfert 1 galaxy NGC 4051, whose spectrum has revealed a complex multicomponent wind. Making use of both RGS and EPIC-pn data, we performed a detailed analysis through a time-dependent photoionization code in combination with spectral and Fourier spectral-timing techniques. The source light curves and the warm absorber parameters obtained from the data were used to simulate the response of the gas due to variations in the ionizing flux of the central source. The resulting time variable spectra were employed to predict the effects of the warm absorber on the time lags and coherence of the energy dependent light curves. We have found that, in the absence of any other lag mechanisms, a warm absorber with the characteristics of the one observed ...

  10. Review of Plasmonic Nanocomposite Metamaterial Absorber

    Directory of Open Access Journals (Sweden)

    Mehdi Keshavarz Hedayati

    2014-02-01

    Full Text Available Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon. These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented.

  11. Wave-Structure Interactions on Point Absorbers - an experimental study

    DEFF Research Database (Denmark)

    Jakobsen, Morten Møller

    used in the case studies is a pitching point absorber (Wavestar). The central part of the thesis deals with the challenges, choices, and experi- ences gained during the Ph.D. The more in-depth technical details and results are presented in peer-reviewed publications and technical reports. The chal...... models. Using a modification by Faltinsen to take into account the relative motion of the device, the contributions from drag, excitation and body motion are determined. 2: Determining the peak pressure on the surface on the device during extreme events and in freak conditions. A great deal of work has...... been done to determine peak pressures on mono-piles worldwide, but only very little on spherical structures. In order to shed more light on the wave induced loads on a hemisphere the peak pressures are measured with the traditional drop test and during impact of so-called freak waves. 3: Implementation...

  12. Influence of radioactive contaminants on absorbed dose estimates for radiopharmaceuticals

    International Nuclear Information System (INIS)

    Several popular radiopharmaceutical products contain low levels of radioactive contaminants. These contaminants increase the radiation absorbed dose to the patient without any increased benefit and, in some cases, with a decrease in image quality. The importance of a contaminant to the radiation dosimetry picture is a function of 1) the contaminant level, 2) the physical half-life of the contaminant, 3) the organ uptake and the biological half-time of the contaminant in the various body systems, and 4) the decay mode, energy, etc. of the contaminant. The general influence of these parameters is discussed in this paper; families of curves are included that reflect the changing importance of contaminant dosimetry with respect to the primary radionuclide as a function of these variables. Several specific examples are also given of currently used radiopharmaceutical products which can contain radioactive contaminants (I-123, In-111, Tl-201, Ir-191m, Rb-82, Au-195m). 7 references, 8 figures, 4 tables

  13. A High Resolution View of the Warm Absorber in the Quasar MR2251-178

    CERN Document Server

    Reeves, J N; Braito, V; Gofford, J; Nardini, E; Turner, T J; Crenshaw, D M; Kraemer, S B

    2013-01-01

    High resolution X-ray spectroscopy of the warm absorber in the nearby quasar, MR2251-178 (z = 0.06398) is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating and the XMM-Newton Reflection Grating Spectrometer, with net exposure times of approximately 400 ks each. A multitude of absorption lines from C to Fe are detected, revealing at least 3 warm absorbing components ranging in ionization parameter from log(\\xi/erg cm s^-1) = 1-3 and with outflow velocities < 500 km/s. The lowest ionization absorber appears to vary between the Chandra and XMM-Newton observations, which implies a radial distance of between 9-17 pc from the black hole. Several broad soft X-ray emission lines are strongly detected, most notably from He-like Oxygen, with FWHM velocity widths of up to 10000 km/s, consistent with an origin from Broad Line Region (BLR) clouds. In addition to the warm absorber, gas partially covering the line of sight to the quasar appears to be present, of typic...

  14. Absorbed fractions for electrons in ellipsoidal volumes

    Science.gov (United States)

    Amato, E.; Lizio, D.; Baldari, S.

    2011-01-01

    We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.

  15. The role of black holes in galaxy formation and evolution.

    Science.gov (United States)

    Cattaneo, A; Faber, S M; Binney, J; Dekel, A; Kormendy, J; Mushotzky, R; Babul, A; Best, P N; Brüggen, M; Fabian, A C; Frenk, C S; Khalatyan, A; Netzer, H; Mahdavi, A; Silk, J; Steinmetz, M; Wisotzki, L

    2009-07-01

    Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies. PMID:19587763

  16. The role of black holes in galaxy formation and evolution

    CERN Document Server

    Cattaneo, A; Binney, J; Dekel, A; Kormendy, J; Mushotzky, R; Babul, A; Best, P N; Brüggen, M; Fabian, A C; Frenk, C S; Khalatyan, A; Netzer, H; Mahdavi, A; Silk, J; Steinmetz, M; Wisotzki, L

    2009-01-01

    Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies.

  17. Random-walk baryogenesis via primordial black holes

    OpenAIRE

    Semiz, İbrahim

    2016-01-01

    Gravitation violates baryon number $B$: A star has a huge amount of it, while a black hole forming from the star has none. Consider primordial black holes before the hadronic annihiliation in the early universe, encountering and absorbing baryons and antibaryons: Each such absorption changes $B$ of the universe by one unit, up or down. But the absorption events are $uncorrelated$ $and$ $random$, hence they amount to a random walk in $B$-space, leading to the expectation of a net $|B|$ at the ...

  18. Neutron absorbers and methods of forming at least a portion of a neutron absorber

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, Donna P; Porter, Douglas L; Swank, W David; Erickson, Arnold W

    2014-12-02

    Methods of forming at least a portion of a neutron absorber include combining a first material and a second material to form a compound, reducing the compound into a plurality of particles, mixing the plurality of particles with a third material, and pressing the mixture of the plurality of particles and the third material. One or more components of neutron absorbers may be formed by such methods. Neutron absorbers may include a composite material including an intermetallic compound comprising hafnium aluminide and a matrix material comprising pure aluminum.

  19. Disturbance of light-absorbing aerosols on the albedo in a winter snowpack of Central Tibet

    Institute of Scientific and Technical Information of China (English)

    Jing Ming; Pengling Wang; Shuyu Zhao; Pengfei Chen

    2013-01-01

    A field observation on the albedo of the snowpack in Central Tibet was conducted in the Nam Co region in the winter of 2011.Snow properties,including grain size and density,were measured in the field,and surface-layer snow samples (down to 5 cm) were collected.The average concentrations of black carbon and dust were 72 ppbm (close to that in the glaciers of Mt.Nyainqentanglha) and 120 ppmm,respectively.Inverse trends were found to exist between the albedo of the snowpack and light-absorbing aerosols (LAAs) as well as grain size growth.Modeling showed that black carbon,dust,and grain growth in the winter snowpack can reduce the broadband albedo by 11%,28%,and 61%,respectively.

  20. Art and the Body Image: about Self and Stereotypes

    OpenAIRE

    Oliveira, Mónica

    2015-01-01

    Today's man is socially absorbed by problematic body issues and everything that this means and involves. Literature, publicity, science, technology and medicine compound these issues in a form of this theme that has never been seen before. In the artistic framework, body image is constantly suffering modifications. Body image in sculpture unfolds itself, assuming different messages and different forms. The body is a synonym of subject, an infinite metaphorical history of our looks...

  1. Space radiation absorbed dose distribution in a human phantom.

    Science.gov (United States)

    Badhwar, G D; Atwell, W; Badavi, F F; Yang, T C; Cleghorn, T F

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  2. Space radiation absorbed dose distribution in a human phantom

    Science.gov (United States)

    Badhwar, G. D.; Atwell, W.; Badavi, F. F.; Yang, T. C.; Cleghorn, T. F.

    2002-01-01

    The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

  3. Specific absorbed fraction in bone tissue and bone marrow resulting from photons distributed in the skeleton

    International Nuclear Information System (INIS)

    The computer code 'ALGAM: Monte Carlo Estimation of Internal Dose from Gamma -ray Sources in a Phanton Man' only provides for an average dose to bone marrow resulting from a photon source distributed in the human body. Since there is no realistic model for the separation of these doses in the present phantom, some modifications were performed in the ALGAM code in order to introduce an heterogeneous skeleton and through this new model it was possible to make the estimation of dose in bone marrow. The specific absorbed fraction resulting from running the new program for 12 monoenergetic photon sources distributed in three source organs - skeleton, red marrow and yellow marrow is presented. The results obtained show that for low photon energies, the old model overestimates the specific absorbed fraction in bone marrow up to a factor of 4; while in bone, it underestimates the specific absorbed fractions up to a factor of 1.6. (Author)

  4. Ultrafast Nonlinear Excitation Dynamics of Black Phosphorus Nanosheets from Visible to Mid-Infrared.

    Science.gov (United States)

    Wang, Kangpeng; Szydłowska, Beata M; Wang, Gaozhong; Zhang, Xiaoyan; Wang, Jing Jing; Magan, John J; Zhang, Long; Coleman, Jonathan N; Wang, Jun; Blau, Werner J

    2016-07-26

    The recent progress on black phosphorus makes it a promising candidate material for broadband nanophotonic devices, especially operating in the mid-infrared spectral region. Here, the excited carrier dynamics and nonlinear optical response of unoxidized black phosphorus nanosheets and their wavelength dependence were systematically studied from 800 nm to 2.1 μm. The wavelength-dependent relaxation times of black phosphorus nanosheets are determined to be 360 fs to 1.36 ps with photon energies from 1.55 to 0.61 eV. In a comparative study with graphene, we found that black phosphorus has a faster carrier relaxation in near- and mid-infrared region. With regard to nonlinear optical absorption, the response of black phosphorus significantly increases from near- to mid-infrared, and black phosphorus is also confirmed to be better as saturable absorber to MoS2 in infrared region. PMID:27281449

  5. Body lice

    Science.gov (United States)

    Lice - body; Pediculosis corporis; Vagabond disease ... Diaz JH. Lice (pediculosis). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases . 8th ...

  6. Bog bodies

    DEFF Research Database (Denmark)

    Lynnerup, Niels

    2015-01-01

    the bog bodies have been studied using medical and natural scientific methods, and recently many bog bodies have been re-examined using especially modern, medical imaging techniques. Because of the preservation of soft tissue, especially the skin, it has been possible to determine lesions and trauma......In northern Europe during the Iron Age, many corpses were deposited in bogs. The cold, wet and anaerobic environment leads in many cases to the preservation of soft tissues, so that the bodies, when found and excavated several thousand years later, are remarkably intact. Since the 19th century....... Conversely, the preservation of bones is less good, as the mineral component has been leached out by the acidic bog. Together with water-logging of collagenous tissue, this means that if the bog body is simply left to dry out when found, as was the case pre-19th century, the bones may literally warp...

  7. Stimulated Black Hole Evaporation

    CERN Document Server

    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.

  8. Astrophysical black holes

    CERN Document Server

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

    2016-01-01

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

  9. Cosmic Black Holes

    OpenAIRE

    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 ...

  10. The New Black

    OpenAIRE

    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...

  11. Black branes as piezoelectrics.

    Science.gov (United States)

    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

  12. Kerr black string flow

    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.

  13. Design of a non-traditional dynamic vibration absorber.

    Science.gov (United States)

    Cheung, Y L; Wong, W O

    2009-08-01

    A non-traditional dynamic vibration absorber is proposed for the minimization of maximum vibration velocity response of a vibrating structure. Unlike the traditional damped absorber configuration, the proposed absorber has a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. Optimum parameters of the proposed absorber are derived based on the fixed-point theory for minimizing the maximum vibration velocity response of a single-degree-of-freedom system under harmonic excitation. The extent of reduction in maximum vibration velocity response of the primary system when using the traditional dynamic absorber is compared with that using the proposed one. Under the optimum tuning condition of the absorbers, it is proved analytically that the proposed absorber provides a greater reduction in maximum vibration velocity response of the primary system than the traditional absorber. PMID:19640019

  14. Design and development of radiation absorber for sighting beam line

    International Nuclear Information System (INIS)

    During the commissioning of Indus-2 , it is necessary to view the synchrotron radiation that will be emanating from the dipole exit ports. The 100 beam line from dipole 11 was earmarked for sighting beam line. The synchrotron radiation power density would be around 340 watts on the photon absorber inside the radiation absorber module, at the specified beam power of Indus-2. The beam striking on this photon absorber produces x-rays and Bremsstrahlung radiation. These are to be stopped and absorbed by radiation absorber. The photon absorber and the radiation absorber are integrated in a single vacuum chamber and actuated by a pneumatic cylinder connected using a bellow. Radiation absorber was needed to isolate the diagnostic components and to protect them from radiation a well as heat when they were not in use. The paper describes the design, calculation and development of the dynamic photon cum radiation absorber. The ultimate vacuum performance is also described. (author)

  15. Evidence for black holes.

    Science.gov (United States)

    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

  16. Black hole statistics

    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

  17. Deforming regular black holes

    CERN Document Server

    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.

  18. Black stain - a review.

    Science.gov (United States)

    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

  19. "Black Capitalism": Toward Controlled Development of Black America

    Science.gov (United States)

    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)

  20. Absorbing Software Testing into the Scrum Method

    Science.gov (United States)

    Tuomikoski, Janne; Tervonen, Ilkka

    In this paper we study, how to absorb software testing into the Scrum method. We conducted the research as an action research during the years 2007-2008 with three iterations. The result showed that testing can and even should be absorbed to the Scrum method. The testing team was merged into the Scrum teams. The teams can now deliver better working software in a shorter time, because testing keeps track of the progress of the development. Also the team spirit is higher, because the Scrum team members are committed to the same goal. The biggest change from test manager’s point of view was the organized Product Owner Team. Test manager don’t have testing team anymore, and in the future all the testing tasks have to be assigned through the Product Backlog.

  1. Thermal neutron absorbing composite organic fiber material

    International Nuclear Information System (INIS)

    Purpose: To obtain clothing materials easy to put on by plasma spray of inorganic material containing elements with a large thermal neutron absorption cross section on a fiberous structure mainly composed of organic fibers. Constitution: The composite organic fiber material comprises flame-spray molding products containing elements with a large thermal neutron absorbing cross section and fiberous structure mainly composed of organic fibers having a melting point lower than that for the flame-spray molding products and they are integrated as a multilayered structure. The flame-spray fabrication is applied by melting and pulverizing starting materials in plasmas and then forming in the shape of a film, sponge or flake on a sheet-like product while carrying them on a plasma stream etc. The binder layer can be saved or reduced significantly by constituting the neutron absorbing material with the flame-spray molding products. (Takahashi, M.)

  2. Fault Detection for Automotive Shock Absorber

    Science.gov (United States)

    Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

    2015-11-01

    Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

  3. Vibration absorber modeling for handheld machine tool

    Science.gov (United States)

    Abdullah, Mohd Azman; Mustafa, Mohd Muhyiddin; Jamil, Jazli Firdaus; Salim, Mohd Azli; Ramli, Faiz Redza

    2015-05-01

    Handheld machine tools produce continuous vibration to the users during operation. This vibration causes harmful effects to the health of users for repeated operations in a long period of time. In this paper, a dynamic vibration absorber (DVA) is designed and modeled to reduce the vibration generated by the handheld machine tool. Several designs and models of vibration absorbers with various stiffness properties are simulated, tested and optimized in order to diminish the vibration. Ordinary differential equation is used to derive and formulate the vibration phenomena in the machine tool with and without the DVA. The final transfer function of the DVA is later analyzed using commercial available mathematical software. The DVA with optimum properties of mass and stiffness is developed and applied on the actual handheld machine tool. The performance of the DVA is experimentally tested and validated by the final result of vibration reduction.

  4. Absorber rod drive for nuclear reactors

    International Nuclear Information System (INIS)

    The invention concerns an absorber rod drive for Boiling Water Reactors, in which a mechanical drive is combined with a hydraulic drive working separately from it, so that both drives are situated concentric within an overall length. The driving torque of a motor is transmitted to a threaded spindle, which moves a free adjacent hollow piston vertically via a fixed nut. The same means are used for the hydraulic liquid which is used as coolant or moderator and there are nozzles, annular gaps and/or bores between the hydraulic system and the reactor pressure vessel for the purpose of pressure compensation. All the components of the absorber rod drive except the sealing housing and the setting drive are situated in one casing tube taking the differential pressure. (orig./HP)

  5. Ultra-broadband terahertz metamaterial absorber

    Science.gov (United States)

    Zhu, Jianfei; Ma, Zhaofeng; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

    2014-07-01

    We demonstrated an ultra-broadband, polarization-insensitive, and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design, each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21 μm is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40°. The full absorption width at half maximum of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

  6. High-performance THz metamaterial absorber

    CERN Document Server

    Zhu, Jianfei; Sun, Wujiong; Ding, Fei; He, Qiong; Zhou, Lei; Ma, Yungui

    2014-01-01

    We demonstrated an ultra-broadband, polarization-insensitive and wide-angle metamaterial absorber for terahertz (THz) frequencies using arrays of truncated pyramid unit structure made of metal-dielectric multilayer composite. In our design each sub-layer behaving as an effective waveguide is gradually modified in their lateral width to realize a wideband response by effectively stitching together the resonance bands of different waveguide modes. Experimentally, our five layer sample with a total thickness 21um is capable of producing a large absorptivity above 80% from 0.7 to 2.3 THz up to the maximum measurement angle 40{\\deg}. The full absorption width at half maximum (FWHM) of our device is around 127%, greater than those previously reported for THz frequencies. Our absorber design has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.

  7. Effect of the bio-absorbent on the microwave absorption property of the flaky CIPs/rubber absorbers

    International Nuclear Information System (INIS)

    Microwave absorbing composites filled with flaky carbonyl iron particles (CIPs) and the bio-absorbent were prepared by using a two-roll mixer and a vulcanizing machine. The electromagnetic (EM) parameters were measured by a vector network analyzer and the reflection loss (RL) was measured by the arch method in the frequency range of 1–4 GHz. The uniform dispersion of the absorbents was verified by comparing the calculated RL with the measured one. The results confirm that as the bio-absorbent was added, the permittivity was increased due to the volume content of absorbents, and the permeability was enlarged owing to the volume content of CIPs and interactions between the two absorbents. The composite filled with bio-absorbents achieved an excellent absorption property at a thickness of 1 mm (minimum RL reaches −7.8 dB), and as the RL was less than −10 dB the absorption band was widest (2.1–3.8 GHz) at a thickness of 2 mm. Therefore, the bio-absorbent is a promising additive candidate on fabricating microwave absorbing composites with a thinner thickness and wider absorption band. - Graphical abstract: Morphology of composites filled with flaky CIPs and the bio-absorbent. The enhancement of bio-absorbent on the electromagnetic absorption property of composites filled with flaky carbonyl iron particles (CIPs) is attributed to the interaction of the two absorbents. The volume content of the FCMPs with the larger shape CIPs play an important role in this effects, the composites filled with irons and bio-absorbents can achieve wider-band and thinner-thickness absorbing materials. - Highlights: • Absorbers filled with bio-absorbents and CIPs was fabricated. • Bio-absorbents enhanced the permittivity and permeability of the composites. • The absorbent interactions play a key role in the enhancement mechanism. • Bio-absorbents enhanced the composite RL in 1–4 GHz

  8. Tuned ball absorber acting in one direction

    Czech Academy of Sciences Publication Activity Database

    Pirner, Miroš; Urushadze, Shota

    US : SEM, 2004 - (Wicks, A.), s. 150-158 ISBN 0-912053-86-0. ISSN 1046-6770. [IMAC-XXII Conference on Structural Dynamic s. Dearborn (US), 26.01.2004-29.01.2004] R&D Projects: GA AV ČR KJB2071303 Institutional research plan: CEZ:AV0Z2071913 Keywords : ball absorber * acceleration * frequency Subject RIV: JM - Building Engineering

  9. Absorbed Doses to Patients in Nuclear Medicine

    International Nuclear Information System (INIS)

    The work with a Swedish catalogue of radiation absorbed doses to patients undergoing nuclear medicine investigations has continued. After the previous report in 1999, biokinetic data and dose estimates (mean absorbed dose to various organs and tissues and effective dose) have been produced for a number of substances: 11C- acetate, 11C- methionine, 18F-DOPA, whole antibody labelled with either 99mTc, 111In, 123I or 131I, fragment of antibody, F(ab')2 labelled with either 99mTc, 111In, 123I or 131I and fragment of antibody, Fab' labelled with either 99mTc, 111In, 123I or 131I. The absorbed dose estimates for these substances have been made from published biokinetic information. For other substances of interest, e.g. 14C-urea (children age 3-6 years), 14C-glycocholic acid, 14C-xylose and 14C-triolein, sufficient literature data have not been available. Therefore, a large number of measurements on patients and volunteers have been carried out, in order to determine the biokinetics and dosimetry for these substances. Samples of breast milk from 50 mothers, who had been subject to nuclear medicine investigations, have been collected at various times after administration of the radiopharmaceutical to the mother. The activity concentration in the breast milk samples has been measured. The absorbed dose to various organs and tissues and the effective dose to the child who ingests the milk have been determined for 17 different radiopharmaceuticals. Based on these results revised recommendations for interruption of breast-feeding after nuclear medicine investigations are suggested

  10. 2D Saturable Absorbers for Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Robert I. Woodward

    2015-11-01

    Full Text Available Two-dimensional (2D nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family of few-layer transition metal dichalcogenides, including MoS2, MoSe2 and WS2.

  11. The Engel algorithm for absorbing Markov chains

    OpenAIRE

    Snell, J. Laurie

    2009-01-01

    In this module, suitable for use in an introductory probability course, we present Engel's chip-moving algorithm for finding the basic descriptive quantities for an absorbing Markov chain, and prove that it works. The tricky part of the proof involves showing that the initial distribution of chips recurs. At the time of writing (circa 1979) no published proof of this was available, though Engel had stated that such a proof had been found by L. Scheller.

  12. Phase separation in systems with absorbing states

    OpenAIRE

    Munoz, M. A.; Marconi, U. Marini Bettolo; Cafiero, R.

    1998-01-01

    We study the problem of phase separation in systems with a positive definite order parameter, and in particular, in systems with absorbing states. Owing to the presence of a single minimum in the free energy driving the relaxation kinetics, there are some basic properties differing from standard phase separation. We study analytically and numerically this class of systems; in particular we determine the phase diagram, the growth laws in one and two dimensions and the presence of scale invaria...

  13. Different pendulum type dynamic vibration absorber aplication

    OpenAIRE

    Мартин, Віктор Євгенович; Дівеєв, Богдан Михайлович; Дорош, Ігор Романович

    2014-01-01

    The paper considers the methods of calculation and optimization of  different pendulum type dynamic vibration absorbers for the vibration reduction of elongated elements. Discrete-continuous models of the dynamics of oversize elongated elements based on the Timoshenko beam theory with attached discrete elements are presented. Algorithms for the vibration reduction of elongated machine elements are obtained.Noise and vibration are associated with many mechanical systems including industrial, h...

  14. Broadband metasurface absorber for solar thermal applications

    Science.gov (United States)

    Wan, C.; Chen, L.; Cryan, M. J.

    2015-12-01

    In this paper we propose a broadband polarization-independent selective absorber for solar thermal applications. It is based on a metal-dielectric-metal metasurface structure, but with an interlayer of absorbing amorphous carbon rather than a low loss dielectric. Optical absorbance results derived from finite difference time domain modelling are shown for ultra-thin carbon layers in air and on 200 nm of gold for a range of carbon thicknesses. A gold-amorphous carbon-gold trilayer with a top layer consisting of a 1D grating is then optimised in 2D to give a sharp transition from strong absorption up to 2 μm to strong reflection above 2 μm resulting in good solar selective performance. The gold was replaced by the high-melting-point metal tungsten, which is shown to have very similar performance to the gold case. 3D simulations then show that the gold-based structure performs well as a square periodic array of squares, however there is low absorption around 400 nm. A cross-based structure is found to increase this absorption without significantly reducing the performance at longer wavelengths.

  15. Photon absorbed dose: the UK standard

    International Nuclear Information System (INIS)

    Since 1988, the primary standard for megavoltage photon dosimetry in the UK has been a graphite calorimeter. The routine calibration of secondary standard ionisation chambers has been provided by NPL directly in terms of absorbed dose to water since then, with users following the 1990 IPSM Code of Practice. Comparisons of the primary standard with NPL's reference ionisation chambers have been carried out annually, and the calibration service has been offered in the spring and autumn each year, for 60Co γ-rays and 4 MV to 19 MV X-rays. The data generated have been analysed and the results of this analysis are presented here. The long-term stability of the NE 2561 chamber, and its value in maintaining the standard of absorbed dose is demonstrated. The utility of TPR as a beam quality parameter is discussed, and the resulting ambiguity in chamber calibration is quantified. The conversion of dose from graphite to water is summarized, and changes in the basis of the NPL absorbed dose standard over the last seven years are described

  16. Development of monofilar rotor hub vibration absorber

    Science.gov (United States)

    Duh, J.; Miao, W.

    1983-01-01

    A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuation at two frequencies using the same dynamic mass. Linear and non-linear analyses of the coupled monofilar/airframe system were developed to study tuning and attenuation characteristics. Based on the analysis, a design was fabricated and impact bench tests verified the calculated non-rotating natural frequencies and mode shapes. Performance characteristics were measured using a rotating absorber test facility. These tests showed significant attenuation of fixed-system 4P hub motions due to 3P inplane rotating-system hub forces. In addition, detuning effects of the 3P monofilar modal response were small due to the nonlinearities and tuning pin slippage. However, attenuation of 4P hub motions due to 5P inplane hub forces was poor. The performance of the 5P monofilar modal response was degraded by torsional motion of the dynamic mass relative to the support arm which resulted in binding of the dynamic components. Analytical design studies were performed to evaluate this torsional motion problem. An alternative design is proposed which may alleviate the torsional motion of the dynamic mass.

  17. Influence of absorbers on the reactivity of the reactor

    International Nuclear Information System (INIS)

    Influence of absorbers on the reactivity of the reactor was calculated by two-group diffusion theory applying corrections for boundary conditions derived from the transport theory because diffusion theory in not applicable in the vicinity of boundary surfaces especially in case of strong absorbers. This report shows the calculations of central absorber efficiency in the core with and without reflector, and efficiency of the group of absorbers randomly placed in the core. Approximation method for determining the efficiency of the absorber is described as well as numerical verification of results. Effective absorber dimensions and the influence of gaps on the reactor dimensions are shown

  18. A study on absorbed dose in the breast tissue using geant4 simulation for mammography

    International Nuclear Information System (INIS)

    As the breast cancer rate is increasing fast in Korean women, people pay more attention to mammography and number of mammography have been increasing dramatically over the last few years. Mammography is the only means to diagnose breast cancer early, but harms caused by radiation exposure shouldn't be overlooked. Therefore, it is important to calculate the radiation dose being absorbed into the breast tissue during the process of mammography for a protective measure against radiation exposure. Because it is impossible to directly measure the radiation dose being absorbed into the human body, statistical calculation methods are commonly used, and most of them are supposed to simulate the interaction between radiation and matter by describing the human body internal structure with anthropomorphic phantoms. However, a simulation using Geant4 Code of Monte Carlo Method, which is well-known as most accurate in calculating the absorbed dose inside the human body, helps calculate exact dose by recreating the anatomical human body structure as it is through the DICOM file of CT. To calculate the absorbed dose in the breast tissue, therefore, this study carried out a simulation using Geant4 Code, and by using the DICOM converted file provided by Geant4, this study changed the human body structure expressed on the CT image data into geometry needed for this simulation. Besides, this study attempted to verify if the dose calculation of Geant4 interlocking with the DICOM file is useful, by comparing the calculated dose provided by this simulation and the measured dose provided by the PTW ion chamber. As a result, under the condition of 28kVp/190mAs, the Difference(%) between the measured dose and the calculated dose was found to be 0.08 %∼0.33 %, and at 28 kVp/70 mAs, the Difference(%) of dose was 0.01 %∼0.16 %, both of which showed results within 2%, the effective difference range. Therefore, this study found out that calculation of the absorbed dose using Geant4

  19. Rotating Brane World Black Holes

    OpenAIRE

    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.

  20. Signifying Bodies

    DEFF Research Database (Denmark)

     In our everyday lives we strive to stay healthy and happy, while we live as our selves, engage with each other, and discover an infinite world of possibilities. Health arises and diminishes as human beings draw on a vibrant ecology of actions, interactions and coactions. Intricate processes of...... biosemiosis connect signifying bodies with their natural surroundings, cultural activities and subjective experiences. Health stretches all the way from the ecosocial surroundings, through the skin and into the self-organizing processes of every living cell. Signifying Bodies lays out a new approach to health...... and health care. Eschewing all forms of dualism, the authors emphasise the interdependency of how we act, think, feel and function. They advocate a relational turn in health care, in which bodies live and learn from suffering and care. In this view, health is inseparable from both living beings and...

  1. Body Imaging

    Science.gov (United States)

    2001-01-01

    The high-tech art of digital signal processing (DSP) was pioneered at NASA's Jet Propulsion Laboratory (JPL) in the mid-1960s for use in the Apollo Lunar Landing Program. Designed to computer enhance pictures of the Moon, this technology became the basis for the Landsat Earth resources satellites and subsequently has been incorporated into a broad range of Earthbound medical and diagnostic tools. DSP is employed in advanced body imaging techniques including Computer-Aided Tomography, also known as CT and CATScan, and Magnetic Resonance Imaging (MRI). CT images are collected by irradiating a thin slice of the body with a fan-shaped x-ray beam from a number of directions around the body's perimeter. A tomographic (slice-like) picture is reconstructed from these multiple views by a computer. MRI employs a magnetic field and radio waves, rather than x-rays, to create images.

  2. Evolution of massive black holes

    OpenAIRE

    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...

  3. Pyrolytic carbon coated black silicon

    OpenAIRE

    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 ...

  4. A HIGH RESOLUTION VIEW OF THE WARM ABSORBER IN THE QUASAR MR 2251-178

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, J. N.; Gofford, J.; Nardini, E. [Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Keele, Staffordshire, ST5 5BG (United Kingdom); Porquet, D. [Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l' Université, F-67000 Strasbourg (France); Braito, V. [INAF - Osservatorio Astronomico di Brera, Via Bianchi 46 I-23807 Merate (Italy); Turner, T. J. [Center for Space Science and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Crenshaw, D. M. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, One Park Place South SE, Suite 700, Atlanta, GA 30303 (United States); Kraemer, S. B., E-mail: j.n.reeves@keele.ac.uk [Institute for Astrophysics and Computational Sciences, Department of Physics, The Catholic University of America, Washington, DC 20064 (United States)

    2013-10-20

    High resolution X-ray spectroscopy of the warm absorber in a nearby quasar, MR 2251-178 (z = 0.06398), is presented. The observations were carried out in 2011 using the Chandra High Energy Transmission Grating (HETG) and the XMM-Newton Reflection Grating Spectrometer, with net exposure times of approximately 400 ks each. A multitude of absorption lines from C to Fe are detected, revealing at least three warm absorbing components ranging in ionization parameter from log (ξ/erg cm s{sup –1}) = 1-3 with outflow velocities ∼< 500 km s{sup –1}. The lowest ionization absorber appears to vary between the Chandra and XMM-Newton observations, which implies a radial distance of between 9 and 17 pc from the black hole. Several broad soft X-ray emission lines are strongly detected, most notably from He-like oxygen, with FWHM velocity widths of up to 10,000 km s{sup –1}, consistent with an origin from broad-line region (BLR) clouds. In addition to the warm absorber, gas partially covering the line of sight to the quasar appears to be present, with a typical column density of N{sub H} = 10{sup 23} cm{sup –2}. We suggest that the partial covering absorber may arise from the same BLR clouds responsible for the broad soft X-ray emission lines. Finally, the presence of a highly ionized outflow in the iron K band from both the 2002 and 2011 Chandra HETG observations appears to be confirmed, which has an outflow velocity of –15600 ± 2400 km s{sup –1}. However, a partial covering origin for the iron K absorption cannot be excluded, resulting from low ionization material with little or no outflow velocity.

  5. Effect of low-Z absorber's thickness on gamma-ray shielding parameters

    International Nuclear Information System (INIS)

    Gamma ray shielding behaviour of any material can be studied by various interaction parameters such as total mass attenuation coefficient (μm); half value layer (HVL); tenth value layer (TVL); effective atomic number (Zeff), electron density (Nel), effective atomic weight (Aeff) and buildup factor. For gamma rays, the accurate measurements of μm (cm2 g−1) theoretically require perfect narrow beam irradiation geometry. However, the practical geometries used for the experimental investigations deviate from perfect-narrowness thereby the multiple scattered photons cause systematic errors in the measured values of μm. Present investigation is an attempt to find the optimum value of absorber thickness (low-Z) for which these errors are insignificant and acceptable. Both experimental and theoretical calculations have been performed to investigate the effect of absorber's thickness on μm of six low-Z (10black; cement-white; clay; red-mud; lime-stone and plaster of paris) at gamma-ray energies 661.66 keV, 1173.24 keV and 1332.50 keV. A computer program (GRIC2-toolkit) was designed for theoretical evaluation of shielding parameters of any material. Good agreement of theoretical and measured values of μm was observed for all absorbers with thickness ≤0.5 mean free paths, thus considered it as optimum thickness for low-Z materials in the selected energy range. White cement was found to possess maximum shielding effectiveness for the selected gamma rays. - Highlights: • Optimum thickness value is 0.5 mfp for low-Z absorbers in energy range 662–1332 keV. • For accurate measurement of μm absorber's thickness should be ≤optimum thickness. • GRIC2-toolkit is useful for γ-ray shielding analysis of composite materials

  6. Unexpected Attraction of Polarotactic Water-Leaving Insects to Matt Black Car Surfaces: Mattness of Paintwork Cannot Eliminate the Polarized Light Pollution of Black Cars

    OpenAIRE

    Miklos Blaho; Tamas Herczeg; Gyorgy Kriska; Adam Egri; Denes Szaz; Alexandra Farkas; Nikolett Tarjanyi; Laszlo Czinke; Andras Barta; Gabor Horvath

    2014-01-01

    The horizontally polarizing surface parts of shiny black cars (the reflection-polarization characteristics of which are similar to those of water surfaces) attract water-leaving polarotactic insects. Thus, shiny black cars are typical sources of polarized light pollution endangering water-leaving insects. A new fashion fad is to make car-bodies matt black or grey. Since rough (matt) surfaces depolarize the reflected light, one of the ways of reducing polarized light pollution is to make matt ...

  7. Body Rainbow

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    Phubu did not know how long hehad walked after leaving Baxoi, buthe did know that he was halfwaybetween home and Lhasa. Feelingthe weight of the sack containingPhumo's body on his back, Fhubuhad calmed down from the grief anddesperation. He had just one wish:to carry Phumo to Lhasa. He knewthat Phumo had gone, and her soulwas no longer in this body. But hewas determined to finish the trip, notonly because he had promised so, butalso that he believed that it would beredemption for him.

  8. Sacralising Bodies

    DEFF Research Database (Denmark)

    Kaur, Ravinder

    2010-01-01

    sacralisation is realised through co-production within a social setting when the object of sacralisation is recognised as such by others. In contemporary Iran, however, the moment of sacralising bodies by the state is also the moment of its own subversion as the political-theological field of martyrdom is......-sacrifice became central to the mass mobilisation against the monarchy. Once the revolutionary government came into existence, this sacred tradition was regulated to create ‘martyrs’ as a fixed category, in order to consolidate the legacy of the revolution. In this political theatre, the dead body is a site of...

  9. Sympathetic vascular transduction is augmented in young normotensive blacks

    Science.gov (United States)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    The purpose of the present study was to determine sympathetic vascular transduction in young normotensive black and white adults. We hypothesized that blacks would demonstrate augmented transduction of muscle sympathetic nerve activity (MSNA) into vascular resistance. To test this hypothesis, MSNA, forearm blood flow, heart rate, and arterial blood pressure were measured during lower body negative pressure (LBNP). At rest, no differences existed in arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance (FVR). Likewise, LBNP elicited comparable responses of these variables for blacks and whites. Baseline MSNA did not differ between blacks and whites, but whites demonstrated greater increases during LBNP (28 +/- 7 vs. 55 +/- 18%, 81 +/- 21 vs. 137 +/- 42%, 174 +/- 81 vs. 556 +/- 98% for -5, -15, and -40 mmHg LBNP, respectively; P forearm vasoconstriction than whites. This finding may contribute to augmented blood pressure reactivity in blacks.

  10. Sympathetic vascular transduction is augmented in young normotensive blacks

    Science.gov (United States)

    Ray, Chester A.; Monahan, Kevin D.

    2002-01-01

    The purpose of the present study was to determine sympathetic vascular transduction in young normotensive black and white adults. We hypothesized that blacks would demonstrate augmented transduction of muscle sympathetic nerve activity (MSNA) into vascular resistance. To test this hypothesis, MSNA, forearm blood flow, heart rate, and arterial blood pressure were measured during lower body negative pressure (LBNP). At rest, no differences existed in arterial blood pressure, heart rate, forearm blood flow, and forearm vascular resistance (FVR). Likewise, LBNP elicited comparable responses of these variables for blacks and whites. Baseline MSNA did not differ between blacks and whites, but whites demonstrated greater increases during LBNP (28 +/- 7 vs. 55 +/- 18%, 81 +/- 21 vs. 137 +/- 42%, 174 +/- 81 vs. 556 +/- 98% for -5, -15, and -40 mmHg LBNP, respectively; P vasoconstriction than whites. This finding may contribute to augmented blood pressure reactivity in blacks.

  11. Dark Spinors Hawking Radiation in String Theory Black Holes

    Directory of Open Access Journals (Sweden)

    R. T. Cavalcanti

    2016-01-01

    Full Text Available The Hawking radiation spectrum of Kerr-Sen axion-dilaton black holes is derived, in the context of dark spinors tunnelling across the horizon. Since a black hole has a well defined temperature, it should radiate in principle all the standard model particles, similar to a black body at that temperature. We investigate the tunnelling of mass dimension one spin-1/2 dark fermions, which are beyond the standard model and are prime candidates to the dark matter. Their interactions with the standard model matter and gauge fields are suppressed by at least one power of unification scale, being restricted just to the Higgs field and to the graviton likewise. The tunnelling method for the emission and absorption of mass dimension one particles across the event horizon of Kerr-Sen axion-dilaton black holes is shown here to provide further evidence for the universality of black hole radiation, further encompassing particles beyond the standard model.

  12. Attribution of aerosol light absorption to black carbon, brown carbon, and dust in China ? interpretations of atmospheric measurements during EAST-AIRE

    OpenAIRE

    Yang, M.; S. G. Howell; Zhuang, J.; Huebert, B. J.

    2008-01-01

    Black carbon, brown carbon, and mineral dust are three of the most important light absorbing aerosols. Their optical properties differ greatly and are distinctive functions of the wavelength of light. Most optical instruments that quantify light absorption, however, are unable to distinguish one type of absorbing aerosol from another. It is thus instructive to separate total absorption from these different light absorbers to gain a better understanding of the optical characteristics of each a...

  13. Carbon black recovery

    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

  14. 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.

  15. Noncommutative Singular Black Holes

    Science.gov (United States)

    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.

  16. Black holes matter

    DEFF Research Database (Denmark)

    Kragh, Helge Stjernholm

    2016-01-01

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

  17. Black holes in inflation

    Science.gov (United States)

    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.

  18. Scattering by Black Holes

    CERN Document Server

    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.

  19. Black Craftsmen Through History.

    Science.gov (United States)

    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…

  20. Black Hole Dynamic Potentials

    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.