Gravity in the Einstein-Gauss-Bonnet theory with the Randall-Sundrum background

International Nuclear Information System (INIS)

Kim, Jihn E.; Lee, Hyun Min

2001-01-01

We obtain the full 5D graviton propagator in the Randall-Sundrum model with the Gauss-Bonnet interaction. From the decomposition of the graviton propagator on the brane, we show that localization of gravity arises in the presence of the Gauss-Bonnet term. We also obtain the metric perturbation for observers on the brane with considering the brane bending and compute the amplitude of one massless graviton exchange. For the positive definite amplitude or no ghost states, the sign of the Gauss-Bonnet term should be negative in our convention, which is compatible with string amplitude computations. In that case, the ghost-free condition is sufficient for obtaining the Newtonian gravity. For a vanishing Gauss-Bonnet coefficient, the brane bending allows us to reproduce the correct graviton polarizations for the effective 4D Einstein gravity

Holographic vector superconductor in Gauss–Bonnet gravity

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Jun-Wang Lu

2016-02-01

Full Text Available In the probe limit, we numerically study the holographic p-wave superconductor phase transitions in the higher curvature theory. Concretely, we study the influences of Gauss–Bonnet parameter α on the Maxwell complex vector model (MCV in the five-dimensional Gauss–Bonnet–AdS black hole and soliton backgrounds, respectively. In the two backgrounds, the improving Gauss–Bonnet parameter α and dimension of the vector operator Δ inhibit the vector condensate. In the black hole, the condensate quickly saturates a stable value at lower temperature. Moreover, both the stable value of condensate and the ratio ωg/Tc increase with α. In the soliton, the location of the second pole of the imaginary part increases with α, which implies that the energy of the quasiparticle excitation increases with the improving higher curvature correction. In addition, the influences of the Gauss–Bonnet correction on the MCV model are similar to the ones on the SU(2 p-wave model, which confirms that the MCV model is a generalization of the SU(2 Yang–Mills model even without the applied magnetic field to some extent.

Ocular surface sensitivity repeatability with Cochet-Bonnet esthesiometer.

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Chao, Cecilia; Stapleton, Fiona; Badarudin, Ezailina; Golebiowski, Blanka

2015-02-01

To determine the repeatability of ocular surface threshold measurements using the Cochet-Bonnet esthesiometer on the same day and 3 months apart. Two separate studies were conducted to determine the repeatability of ocular surface threshold measurements made on the same day (n = 20 subjects) and 3 months apart (n = 29 subjects). The Cochet-Bonnet esthesiometer was used to measure corneal and inferior conjunctival thresholds using the ascending method of limits. The pressure exerted by the Cochet-Bonnet esthesiometer was determined using an analytical balance, for both the 0.08- and 0.12-mm-diameter filaments. This calibration was then used to convert filament length measurements to pressure. Repeatability was determined using a Bland and Altman analysis. The pressure exerted at each filament length differed between the two filament diameters. The measured pressure also differed from values provided by the manufacturer. Repeatability of threshold measurements at the central cornea was shown to be good, with better repeatability for same-day measurements (coefficient of repeatability [CoR] = ±0.23 g/mm²) than for those 3 months apart (CoR = ±0.52 g/mm²). Threshold measurements at the inferior conjunctiva, in contrast, were poorly repeatable (CoR = ±12.78 g/mm²). Cochet-Bonnet esthesiometry is repeatable when performed on the central cornea on the same day and 3 months apart, but this instrument is not recommended for conjunctival threshold measurements.

Noether symmetries in Gauss-Bonnet-teleparallel cosmology.

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Capozziello, Salvatore; De Laurentis, Mariafelicia; Dialektopoulos, Konstantinos F

2016-01-01

A generalized teleparallel cosmological model, [Formula: see text], containing the torsion scalar T and the teleparallel counterpart of the Gauss-Bonnet topological invariant [Formula: see text], is studied in the framework of the Noether symmetry approach. As [Formula: see text] gravity, where [Formula: see text] is the Gauss-Bonnet topological invariant and R is the Ricci curvature scalar, exhausts all the curvature information that one can construct from the Riemann tensor, in the same way, [Formula: see text] contains all the possible information directly related to the torsion tensor. In this paper, we discuss how the Noether symmetry approach allows one to fix the form of the function [Formula: see text] and to derive exact cosmological solutions.

Boundary causality versus hyperbolicity for spherical black holes in Gauss–Bonnet gravity

International Nuclear Information System (INIS)

Andrade, Tomás; Cáceres, Elena; Keeler, Cynthia

2017-01-01

We explore the constraints boundary causality places on the allowable Gauss–Bonnet gravitational couplings in asymptotically AdS spaces, specifically considering spherical black hole solutions. We additionally consider the hyperbolicity properties of these solutions, positing that hyperbolicity-violating solutions are sick solutions whose causality properties provide no information about the theory they reside in. For both signs of the Gauss–Bonnet coupling, spherical black holes violate boundary causality at smaller absolute values of the coupling than planar black holes do. For negative coupling, as we tune the Gauss–Bonnet coupling away from zero, both spherical and planar black holes violate hyperbolicity before they violate boundary causality. For positive coupling, the only hyperbolicity-respecting spherical black holes which violate boundary causality do not do so appreciably far from the planar bound. Consequently, eliminating hyperbolicity-violating solutions means the bound on Gauss–Bonnet couplings from the boundary causality of spherical black holes is no tighter than that from planar black holes. (paper)

P-T phase diagram of a holographic s+p model from Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Nie, Zhang-Yu; Zeng, Hui

2015-01-01

In this paper, we study the holographic s+p model in 5-dimensional bulk gravity with the Gauss-Bonnet term. We work in the probe limit and give the Δ-T phase diagrams at three different values of the Gauss-Bonnet coefficient to show the effect of the Gauss-Bonnet term. We also construct the P-T phase diagrams for the holographic system using two different definitions of the pressure and compare the results.

Noether symmetries in Gauss-Bonnet-teleparallel cosmology

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Capozziello, Salvatore [Universita' di Napoli' ' Federico II' ' , Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Napoli (Italy); INFN Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Napoli (Italy); Gran Sasso Science Institute (INFN), L' Aquila (Italy); Tomsk State Pedagogical University, Tomsk (Russian Federation); De Laurentis, Mariafelicia [INFN Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Napoli (Italy); Tomsk State Pedagogical University, Tomsk (Russian Federation); Goethe University, Institute for Theoretical Physics, Frankfurt (Germany); Laboratory of Theoretical Cosmology, Tomsk State University of Control Systems and Radioelectronics (TUSUR), Tomsk (Russian Federation); Dialektopoulos, Konstantinos F. [Universita' di Napoli' ' Federico II' ' , Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Napoli (Italy); INFN Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Napoli (Italy)

2016-11-15

A generalized teleparallel cosmological model, f(T{sub G},T), containing the torsion scalar T and the teleparallel counterpart of the Gauss-Bonnet topological invariant T{sub G}, is studied in the framework of the Noether symmetry approach. As f(G, R) gravity, where G is the Gauss-Bonnet topological invariant and R is the Ricci curvature scalar, exhausts all the curvature information that one can construct from the Riemann tensor, in the same way, f(T{sub G},T) contains all the possible information directly related to the torsion tensor. In this paper, we discuss how the Noether symmetry approach allows one to fix the form of the function f(T{sub G},T) and to derive exact cosmological solutions. (orig.)

Resurgence and hydrodynamic attractors in Gauss-Bonnet holography

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Casalderrey-Solana, Jorge; Gushterov, Nikola I.; Meiring, Ben

2018-04-01

We study the convergence of the hydrodynamic series in the gravity dual of Gauss-Bonnet gravity in five dimensions with negative cosmological constant via holography. By imposing boost invariance symmetry, we find a solution to the Gauss-Bonnet equation of motion in inverse powers of the proper time, from which we can extract high order corrections to Bjorken flow for different values of the Gauss-Bonnet parameter λGB. As in all other known examples the gradient expansion is, at most, an asymptotic series which can be understood through applying the techniques of Borel-Padé summation. As expected from the behaviour of the quasi-normal modes in the theory, we observe that the singularities in the Borel plane of this series show qualitative features that interpolate between the infinitely strong coupling limit of N=4 Super Yang Mills theory and the expectation from kinetic theory. We further perform the Borel resummation to constrain the behaviour of hydrodynamic attractors beyond leading order in the hydrodynamic expansion. We find that for all values of λGB considered, the convergence of different initial conditions to the resummation and its hydrodynamization occur at large and comparable values of the pressure anisotropy.

Holographic p-wave superfluid in Gauss–Bonnet gravity

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Liu, Shancheng; Pan, Qiyuan; Jing, Jiliang

2017-01-01

We construct the holographic p-wave superfluid in Gauss–Bonnet gravity via a Maxwell complex vector field model and investigate the effect of the curvature correction on the superfluid phase transition in the probe limit. We obtain the rich phase structure and find that the higher curvature correction hinders the condensate of the vector field but makes it easier for the appearance of translating point from the second-order transition to the first-order one or for the emergence of the Cave of Winds. Moreover, for the supercurrents versus the superfluid velocity, we observe that our results near the critical temperature are independent of the Gauss–Bonnet parameter and agree well with the Ginzburg–Landau prediction.

Holographic p-wave superfluid in Gauss–Bonnet gravity

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Liu, Shancheng [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China); Pan, Qiyuan, E-mail: panqiyuan@126.com [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China); Jing, Jiliang, E-mail: jljing@hunnu.edu.cn [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China)

2017-02-10

We construct the holographic p-wave superfluid in Gauss–Bonnet gravity via a Maxwell complex vector field model and investigate the effect of the curvature correction on the superfluid phase transition in the probe limit. We obtain the rich phase structure and find that the higher curvature correction hinders the condensate of the vector field but makes it easier for the appearance of translating point from the second-order transition to the first-order one or for the emergence of the Cave of Winds. Moreover, for the supercurrents versus the superfluid velocity, we observe that our results near the critical temperature are independent of the Gauss–Bonnet parameter and agree well with the Ginzburg–Landau prediction.

Modulation of histone deacetylase attenuates naloxone-precipitated opioid withdrawal syndrome.

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Rehni, Ashish K; Singh, Nirmal; Rachamalla, Mahesh; Tikoo, Kulbhushan

2012-06-01

The present study has been designed to investigate the effect of selective inhibitors of histone deacetylase and/or N-acetyl-Asp-Glu-Val-Asp-al (Ac-DEVD-CHO), a selective interleukin-1β converting enzyme inhibitor, on the development of naloxone-induced opioid withdrawal syndrome both in vitro and in vivo and the effect of histone deacetylase inhibition on histone H3 acetylation in brain. Sub-acute morphine administration followed by a single injection of naloxone (8 mg/kg, i.p.) was used to precipitate opioid withdrawal syndrome in mice. Behavioral observations were made immediately after naloxone treatment. Withdrawal syndrome was quantitatively assessed in terms of withdrawal severity score and frequency of jumping, rearing, fore paw licking and circling. Separately naloxone-induced contraction in morphine-dependent isolated rat ileum was employed as an in vitro model. An isobolographic study design was employed to assess potential synergistic activity between trichostatin A and Ac-DEVD-CHO. Brain histone acetylation status was examined by western blotting. Injection of naloxone precipitated a severe form of abstinence syndrome in morphine-dependent mice along with strong contracture in isolated rat ileum. Administration of tributyrin (1.5, 3 and 6 g/kg, p.o.), trichostatin A (0.3, 1.0 and 3.0 mg/kg, p.o.) and Ac-DEVD-CHO (0.3, 1.0 and 3.0 mg/kg, p.o.) markedly and dose dependently attenuated naloxone-induced morphine withdrawal syndrome in vivo as well as in vitro in rat ileum. Trichostatin A was also observed to exert a synergistic interaction with Ac-DEVD-CHO. Western blot analysis revealed that multiple administration with the effective dose of tributyrin or trichostatin A in the in vivo experiments induced hyperacetylation of histone H3 in the mouse brain. Thus, it is proposed that histone deacetylase activation linked mechanism might be involved in the development of opioid dependence and the precipitation of its withdrawal syndrome.

Rotating black holes in dilatonic Einstein-Gauss-Bonnet theory.

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Kleihaus, Burkhard; Kunz, Jutta; Radu, Eugen

2011-04-15

We construct generalizations of the Kerr black holes by including higher-curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. We show that the domain of existence of these Einstein-Gauss-Bonnet-dilaton (EGBD) black holes is bounded by the Kerr black holes, the critical EGBD black holes, and the singular extremal EGBD solutions. The angular momentum of the EGBD black holes can exceed the Kerr bound. The EGBD black holes satisfy a generalized Smarr relation. We also compare their innermost stable circular orbits with those of the Kerr black holes and show the existence of differences which might be observable in astrophysical systems.

Note on inflation with a tachyon rolling on the Gauss-Bonnet brane

International Nuclear Information System (INIS)

Paul, B.C.; Sami, M.

2004-01-01

In this paper we study the tachyonic inflation in brane world cosmology with Gauss-Bonnet term in the bulk. We obtain the exact solution of slow roll equations in case of exponential potential. We attempt to implement the proposal of J. E. Lidsey and N. J. Nunes [Phys. Rev. D 67, 103510 (2003)] for the tachyon condensate rolling on the Gauss-Bonnet brane and discuss the difficulties associated with the proposal

Eikonal instability of Gauss-Bonnet-(anti-)-de Sitter black holes

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Konoplya, R. A.; Zhidenko, A.

2017-05-01

Here we have shown that asymptotically anti-de Sitter (AdS) black holes in the Einstein-Gauss-Bonnet (GB) theory are unstable under linear perturbations of space-time in some region of parameters. This (eikonal) instability develops at high multipole numbers. We found the exact parametric regions of the eikonal instability and extended this consideration to asymptotically flat and de Sitter cases. The approach to the threshold of instability is driven by purely imaginary quasinormal modes, which are similar to those found recently in Grozdanov, Kaplis, and Starinets, [J. High Energy Phys. 07 (2016) 151, 10.1007/JHEP07(2016)151] for the higher curvature corrected black hole with the planar horizon. The found instability may indicate limits of holographic applicability of the GB-AdS backgrounds. Recently, through the analysis of critical behavior in AdS space-time in the presence of the Gauss-Bonnet term, it was shown [Deppe et al, Phys. Rev. Lett. 114, 071102 (2015), 10.1103/PhysRevLett.114.071102], that, if the total energy content of the AdS space-time is small, then no black holes can be formed with mass less than some critical value. A similar mass gap was also found when considering collapse of mass shells in asymptotically flat Gauss-Bonnet theories [Frolov, Phys. Rev. Lett. 115, 051102 (2015), 10.1103/PhysRevLett.115.051102]. The found instability of all sufficiently small Einstein-Gauss-Bonnet-AdS, dS and asymptotically flat black holes may explain the existing mass gaps in their formation.

The Gauss-Bonnet identity in quartic gravitation theories

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Gomes, M.

1989-01-01

The possible modifications in Gauss-Bonnet relation due to quantum oscillations are studied. The introduction of quantum operator correspondent in the function of two points, in space without singularities is calculated. (M.C.K.)

The second law in four-dimensional Einstein–Gauss–Bonnet gravity

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Chatterjee, Saugata; Parikh, Maulik

2014-01-01

The topological contribution of a Gauss–Bonnet term in four dimensions to black hole entropy opens up the possibility of a violation of the second law of thermodynamics in black hole mergers. We show, however, that the second law is not violated in the regime where Einstein–Gauss–Bonnet holds as an effective theory and black holes can be treated thermodynamically. For mergers of anti-de Sitter (AdS) black holes, the second law appears to be violated even in Einstein gravity; we argue, however, that the second law holds when gravitational potential energy is taken into account. (paper)

Gauss-Bonnet actions and their dimensionally reduced descendants

International Nuclear Information System (INIS)

Mueller-Hoissen, F.

1989-01-01

A brief introduction to Gauss-Bonnet type generalizations of the Einstein-Hilbert gravity action in more than four dimensions is given and the structure of associated (effective) theories obtained by dimensional reduction is discussed. (author)

Phase space of modified Gauss-Bonnet gravity

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Carloni, Sante [Universidade de Lisboa-UL, Centro Multidisciplinar de Astrofisica-CENTRA, Instituto Superior Tecnico-IST, Lisbon (Portugal); Mimoso, Jose P. [Instituto de Astrofisica e Ciencias do Espaco, Universidade de Lisboa, Departamento de Fisica, Faculdade de Ciencias, Lisbon (Portugal)

2017-08-15

We investigate the evolution of non-vacuum Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetimes with any spatial curvature in the context of Gauss-Bonnet gravity. The analysis employs a new method which enables us to explore the phase space of any specific theory of this class. We consider several examples, discussing the transition from a decelerating into an acceleration universe within these theories. We also deduce from the dynamical equations some general conditions on the form of the action which guarantee the presence of specific behaviours like the emergence of accelerated expansion. As in f(R) gravity, our analysis shows that there is a set of initial conditions for which these models have a finite time singularity which can be an attractor. The presence of this instability also in the Gauss-Bonnet gravity is to be ascribed to the fourth-order derivative in the field equations, i.e., is the direct consequence of the higher order of the equations. (orig.)

Energy conditions in modified Gauss-Bonnet gravity

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Garcia, Nadiezhda Montelongo; Harko, Tiberiu; Lobo, Francisco S. N.; Mimoso, Jose P.

2011-01-01

In considering alternative higher-order gravity theories, one is liable to be motivated in pursuing models consistent and inspired by several candidates of a fundamental theory of quantum gravity. Indeed, motivations from string/M theory predict that scalar field couplings with the Gauss-Bonnet invariant, G, are important in the appearance of nonsingular early time cosmologies. In this work, we discuss the viability of an interesting alternative gravitational theory, namely, modified Gauss-Bonnet gravity or f(G) gravity. We consider specific realistic forms of f(G) analyzed in the literature that account for the late-time cosmic acceleration and that have been found to cure the finite-time future singularities present in the dark energy models. We present the general inequalities imposed by the energy conditions and use the recent estimated values of the Hubble, deceleration, jerk and snap parameters to examine the viability of the above-mentioned forms of f(G) imposed by the weak energy condition.

Gravitational quasinormal modes of static Einstein-Gauss-Bonnet anti-de Sitter black holes

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Ma, Hong; Li, Jin

2018-04-01

In this paper, we describe quasinormal modes (QNMs) for gravitational perturbations of Einstein-Gauss-Bonnet black holes (BHs) in higher dimensional spacetimes, and derive the corresponding parameters of such black holes in three types of spacetime (flat, de Sitter (dS) and anti-de Sitter (AdS)). Our attention is concentrated on discussing the (in)stability of Einstein-Gauss-Bonnet AdS BHs through the temporal evolution of all types of gravitational perturbation fields (tensor, vector and scalar). It is concluded that the potential functions in vector and scalar gravitational perturbations have negative regions, which suppress quasinormal ringing. Furthermore, the influences of the Gauss-Bonnet coupling parameter α, the number of dimensions n and the angular momentum quantum number l on the Einstein-Gauss-Bonnet AdS BHs quasinormal spectrum are analyzed. The QNM frequencies have greater oscillation and lower damping rate with the growth of α. This indicates that QNM frequencies become increasingly unstable with large α. Meanwhile, the dynamic evolutions of the perturbation field are compliant with the results of computation from the Horowitz and Hubeny method. Because the number of extra dimensions is connected with the string scale, the relationship between α and properties of Einstein-Gauss-Bonnet AdS BHs might be beneficial for the exploitation of string theory and extra-dimensional brane worlds. Supported by FAPESP (2012/08934-0), National Natural Science Foundation of China (11205254, 11178018, 11375279, 11605015), the Natural Science Foundation Project of CQ CSTC (2011BB0052), and the Fundamental Research Funds for the Central Universities (106112016CDJXY300002, 106112017CDJXFLX0014, CDJRC10300003)

Extremal dyonic black holes in D=4 Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Chen, C.-M.; Gal'tsov, Dmitri V.; Orlov, Dmitry G.

2008-01-01

We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant a. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of a to continuous domains in the plane (a,q m ) where q m is the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordstroem solution but not to the extremal dyons of the Einstein-Maxwell-dilaton theory. Both solutions have the same dependence of the horizon radius in terms of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature-corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.

Effects of backreaction on power-Maxwell holographic superconductors in Gauss-Bonnet gravity

Energy Technology Data Exchange (ETDEWEB)

Salahi, Hamid Reza; Montakhab, Afshin [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Sheykhi, Ahmad [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)

2016-10-15

We analytically and numerically investigate the properties of s-wave holographic superconductors by considering the effects of scalar and gauge fields on the background geometry in five-dimensional Einstein-Gauss-Bonnet gravity. We assume the gauge field to be in the form of the power-Maxwell nonlinear electrodynamics. We employ the Sturm-Liouville eigenvalue problem for analytical calculation of the critical temperature and the shooting method for the numerical investigation. Our numerical and analytical results indicate that higher curvature corrections affect condensation of the holographic superconductors with backreaction. We observe that the backreaction can decrease the critical temperature of the holographic superconductors, while the power-Maxwell electrodynamics and Gauss-Bonnet coefficient term may increase the critical temperature of the holographic superconductors. We find that the critical exponent has the mean-field value β = 1/2, regardless of the values of Gauss-Bonnet coefficient, backreaction and power-Maxwell parameters. (orig.)

Collapsing spherical star in Scalar-Einstein-Gauss-Bonnet gravity with a quadratic coupling

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Chakrabarti, Soumya

2018-04-01

We study the evolution of a self interacting scalar field in Einstein-Gauss-Bonnet theory in four dimension where the scalar field couples non minimally with the Gauss-Bonnet term. Considering a polynomial coupling of the scalar field with the Gauss-Bonnet term, a self-interaction potential and an additional perfect fluid distribution alongwith the scalar field, we investigate different possibilities regarding the outcome of the collapsing scalar field. The strength of the coupling and choice of the self-interaction potential serves as the pivotal initial conditions of the models presented. The high degree of non-linearity in the equation system is taken care off by using a method of invertibe point transformation of anharmonic oscillator equation, which has proven itself very useful in recent past while investigating dynamics of minimally coupled scalar fields.

DNA packing in chromatine, a manifestation of the Bonnet transformation.

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Blum, Z; Lidin, S

1988-08-01

The packing of DNA is described using the formalism of differential geometry. Winding of the DNA double helix around the histone 2-5 octamer forming a nucleosome and the condensation of the so-formed bead-on-a-string chromatine aided by histone 1 is interpreted as two consecutive isometric, i.e. Bonnet, transformations. The DNA double helix can be approximated to a helicoid which can be transformed isometrically to a catenoid, an approximation of the nucleosome. Owing to the organization of the histone octamer the extended chromatine takes a helicoidal shape allowing a second Bonnet transformation to consummate the condensation into a chromatine fibre.

Static solutions with nontrivial boundaries for the Einstein-Gauss-Bonnet theory in vacuum

International Nuclear Information System (INIS)

Dotti, Gustavo; Oliva, Julio; Troncoso, Ricardo

2010-01-01

The classification of a certain class of static solutions for the Einstein-Gauss-Bonnet theory in vacuum is performed in d≥5 dimensions. The class of metrics under consideration is such that the spacelike section is a warped product of the real line and an arbitrary base manifold. It is shown that for a generic value of the Gauss-Bonnet coupling, the base manifold must be necessarily Einstein, with an additional restriction on its Weyl tensor for d>5. The boundary admits a wider class of geometries only in the special case when the Gauss-Bonnet coupling is such that the theory admits a unique maximally symmetric solution. The additional freedom in the boundary metric enlarges the class of allowed geometries in the bulk, which are classified within three main branches, containing new black holes and wormholes in vacuum.

A geological survey of the Lac du Bonnet batholith, Manitoba

International Nuclear Information System (INIS)

McCrank, G.F.D.

1985-02-01

This report presents the results of a geological survey of the Lac du Bonnet batholith in Manitoba. The survey consisted of field mapping of the lithologies and the joint systems throughout the batholith, and the examination of lineaments identified on aerial photographs and Landsat imagery. Petrographic descriptions and a map of the lithologies, an analysis of the fracture systems and a lineament map are presented. The results of various regional geophysical surveys were used as an aid to the interpretation of the batholith's contacts and in the interpretation of lineaments as possible faults. A comparison of the Lac du Bonnet Batholith with the Eye-Dashwa Lakes Pluton near Atikokan, Ontario is also presented

Quintessence background for 5D Einstein-Gauss-Bonnet black holes

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Ghosh, Sushant G.; Amir, Muhammed; Maharaj, Sunil D.

2017-08-01

As we know that the Lovelock theory is an extension of the general relativity to the higher-dimensions, in this theory the first- and the second-order terms correspond to general relativity and the Einstein-Gauss-Bonnet gravity, respectively. We obtain a 5D black hole solution in Einstein-Gauss-Bonnet gravity surrounded by the quintessence matter, and we also analyze their thermodynamical properties. Owing to the quintessence corrected black hole, the thermodynamic quantities have also been corrected except for the black hole entropy, and a phase transition is achievable. The phase transition for the thermodynamic stability is characterized by a discontinuity in the specific heat at r=r_C, with the stable (unstable) branch for r ) r_C.

Second-order transport, quasinormal modes and zero-viscosity limit in the Gauss-Bonnet holographic fluid

Energy Technology Data Exchange (ETDEWEB)

Grozdanov, Sašo [Instituut-Lorentz for Theoretical Physics, Leiden University, Niels Bohrweg 2, Leiden 2333 CA (Netherlands); Starinets, Andrei O. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

2017-03-30

Gauss-Bonnet holographic fluid is a useful theoretical laboratory to study the effects of curvature-squared terms in the dual gravity action on transport coefficients, quasinormal spectra and the analytic structure of thermal correlators at strong coupling. To understand the behavior and possible pathologies of the Gauss-Bonnet fluid in 3+1 dimensions, we compute (analytically and non-perturbatively in the Gauss-Bonnet coupling) its second-order transport coefficients, the retarded two- and three-point correlation functions of the energy-momentum tensor in the hydrodynamic regime as well as the relevant quasinormal spectrum. The Haack-Yarom universal relation among the second-order transport coefficients is violated at second order in the Gauss-Bonnet coupling. In the zero-viscosity limit, the holographic fluid still produces entropy, while the momentum diffusion and the sound attenuation are suppressed at all orders in the hydrodynamic expansion. By adding higher-derivative electromagnetic field terms to the action, we also compute corrections to charge diffusion and identify the non-perturbative parameter regime in which the charge diffusion constant vanishes.

Isometric surfaces with a common mean curvature and the problem of Bonnet pairs

International Nuclear Information System (INIS)

Sabitov, Idzhad Kh

2012-01-01

Simple methods are used to give new proofs, and sometimes to make them more precise, of basic theorems on isometric surfaces with a common mean curvature, which are usually called Bonnet pairs. The considerations are conducted under the assumption of minimally admissible smoothness of the objects in question, and certain necessary or sufficient criteria are given for the non-existence of Bonnet pairs with a common non-constant mean curvature among compact surfaces. Bibliography: 26 titles.

Quintessence background for 5D Einstein-Gauss-Bonnet black holes

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Sushant G. [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa); Centre for Theoretical Physics, New Delhi (India); Amir, Muhammed [Centre for Theoretical Physics, New Delhi (India); Maharaj, Sunil D. [University of KwaZulu-Natal, Astrophysics and Cosmology Research Unit, School of Mathematics, Statistics and Computer Science, Durban (South Africa)

2017-08-15

As we know that the Lovelock theory is an extension of the general relativity to the higher-dimensions, in this theory the first- and the second-order terms correspond to general relativity and the Einstein-Gauss-Bonnet gravity, respectively. We obtain a 5D black hole solution in Einstein-Gauss-Bonnet gravity surrounded by the quintessence matter, and we also analyze their thermodynamical properties. Owing to the quintessence corrected black hole, the thermodynamic quantities have also been corrected except for the black hole entropy, and a phase transition is achievable. The phase transition for the thermodynamic stability is characterized by a discontinuity in the specific heat at r = r{sub C}, with the stable (unstable) branch for r < (>) r{sub C}. (orig.)

Charged Rényi entropies in CFTs with Einstein-Gauss-Bonnet holographic duals

Science.gov (United States)

Pastras, Georgios; Manolopoulos, Dimitrios

2014-11-01

We calculate the Rényi entropy S q ( μ, λ), for spherical entangling surfaces in CFT's with Einstein-Gauss-Bonnet-Maxwell holographic duals. Rényi entropies must obey some interesting inequalities by definition. However, for Gauss-Bonnet couplings λ, larger than specific value, but still allowed by causality, we observe a violation of the inequality , which is related to the existence of negative entropy black holes, providing interesting restrictions in the bulk theory. Moreover, we find an interesting distinction of the behaviour of the analytic continuation of S q ( μ, λ) for imaginary chemical potential, between negative and non-negative λ.

Fate of black branes in Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Suranyi, P.; Wijewardhana, L. C. R.; Vaz, C.

2009-01-01

Black branes are studied in Einstein-Gauss-Bonnet gravity. Evaporation drives black branes toward one of two singularities depending on the sign of α, the Gauss-Bonnet coupling. For positive α and sufficiently large ratio √(α)/L, where L/2π is the radius of compactification, black branes avoid the Gregory-Laflamme (GL) instability before reaching a critical state. No black branes with the radius of horizon smaller than the critical value can exist. Approaching the critical state branes have a nonzero Hawking temperature. For negative α all black branes encounter the GL instability. No black branes may exist outside of the interval of the critical values 0≤β h 2 and r h is the radius of horizon of the black brane. The first order phase transition line of GL transitions ends in a second order phase transition point at β=0.

History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term

Energy Technology Data Exchange (ETDEWEB)

Debnath, Subhra; Sanyal, Abhik Kumar [Jangipur College, Department of Physics, Murshidabad (India); Ruz, Soumendra Nath [Ramananda Centenary College, Department of Physics, Purulia (India); Mandal, Ranajit [University of Kalyani, Department of Physics, Nadia (India)

2017-05-15

Gauss-Bonnet-dilatonic coupling in four dimensions plays an important role to explain late-time cosmic evolution. However, this term is an outcome of the low energy string effective action and thus ought to be important in the early universe too. Unfortunately, a phase-space formulation of such a theory does not exist in the literature due to branching. We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to a higher-order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling. Such an action unifies early inflation with late-time cosmic acceleration. The quantum version of the theory is also well behaved. (orig.)

History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term

International Nuclear Information System (INIS)

Debnath, Subhra; Sanyal, Abhik Kumar; Ruz, Soumendra Nath; Mandal, Ranajit

2017-01-01

Gauss-Bonnet-dilatonic coupling in four dimensions plays an important role to explain late-time cosmic evolution. However, this term is an outcome of the low energy string effective action and thus ought to be important in the early universe too. Unfortunately, a phase-space formulation of such a theory does not exist in the literature due to branching. We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to a higher-order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling. Such an action unifies early inflation with late-time cosmic acceleration. The quantum version of the theory is also well behaved. (orig.)

Stationary vs. singular points in an accelerating FRW cosmology derived from six-dimensional Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Elizalde, E.; Makarenko, A.N.; Obukhov, V.V.; Osetrin, K.E.; Filippov, A.E.

2007-01-01

Six-dimensional Einstein-Gauss-Bonnet gravity (with a linear Gauss-Bonnet term) is investigated. This theory is inspired by basic features of results coming from string and M-theory. Dynamical compactification is carried out and it is seen that a four-dimensional accelerating FRW universe is recovered, when the two-dimensional internal space radius shrinks. A non-perturbative structure of the corresponding theory is identified which has either three or one stable fixed points, depending on the Gauss-Bonnet coupling being positive or negative. A much richer structure than in the case of the perturbative regime of the dynamical compactification recently studied by Andrew, Bolen, and Middleton is exhibited

On static black holes solutions in Einstein and Einstein-Gauss-Bonnet gravity with topology [Formula: see text].

Science.gov (United States)

Dadhich, Naresh; Pons, Josep M

We study static black hole solutions in Einstein and Einstein-Gauss-Bonnet gravity with the topology of the product of two spheres, [Formula: see text], in higher dimensions. There is an unusual new feature of the Gauss-Bonnet black hole: the avoidance of a non-central naked singularity prescribes a mass range for the black hole in terms of [Formula: see text]. For an Einstein-Gauss-Bonnet black hole a limited window of negative values for [Formula: see text] is also permitted. This topology encompasses black strings, branes, and generalized Nariai metrics. We also give new solutions with the product of two spheres of constant curvature.

Simple compactifications and black p-branes in Gauss-Bonnet and Lovelock theories

International Nuclear Information System (INIS)

Giribet, Gaston; Oliva, Julio; Troncoso, Ricardo

2006-01-01

We look for the existence of asymptotically flat simple compactifications of the form M D-p x T p in D-dimensional gravity theories with higher powers of the curvature. Assuming the manifold M D-p to be spherically symmetric, it is shown that the Einstein-Gauss-Bonnet theory admits this class of solutions only for the pure Einstein-Hilbert or Gauss-Bonnet Lagrangians, but not for an arbitrary linear combination of them. Once these special cases have been selected, the requirement of spherical symmetry is no longer relevant since actually any solution of the pure Einstein or pure Gauss-Bonnet theories can then be toroidally extended to higher dimensions. Depending on p and the spacetime dimension, the metric on M D-p may describe a black hole or a spacetime with a conical singularity, so that the whole spacetime describes a black or a cosmic p-brane, respectively. For the purely Gauss-Bonnet theory it is shown that, if M D-p is four-dimensional, a new exotic class of black hole solutions exists, for which spherical symmetry can be relaxed. Under the same assumptions, it is also shown that simple compactifications acquire a similar structure for a wide class of theories among the Lovelock family which accepts this toroidal extension. The thermodynamics of black p-branes is also discussed, and it is shown that a thermodynamical analogue of the Gregory-Laflamme transition always occurs regardless the spacetime dimension or the theory considered, hence not only for General Relativity. Relaxing the asymptotically flat behavior, it is also shown that exact black brane solutions exist within a very special class of Lovelock theories

A note on the viability of Gauss-Bonnet cosmology

International Nuclear Information System (INIS)

Chingangbam, R.; Sami, M.; Tretyakov, P.V.; Toporensky, A.V.

2008-01-01

In this Letter, we analyze the viability of a vacuum Gauss-Bonnet cosmology by examining the dynamics of the homogeneous and anisotropic background in 4+1 dimensions. The trajectories of the system either originate from the standard singularity or from non-standard type, the later is characterized by the divergence of time derivative of the Hubble parameters for its finite value. At the onset, the system should relax to Einstein phase at late times as the effect of Gauss-Bonnet term becomes negligible in the low energy regime. However, we find that most of the trajectories emerging from the standard big-bang singularity lead to future re-collapse whereas the system beginning its evolution from the non-standard singularity enters the Kasner regime at late times. This leads to the conclusion that the measure of trajectories giving rise to a smooth evolution from a standard singularity to the Einstein phase is negligibly small for generic initial conditions

One-loop effective action for non-local modified Gauss-Bonnet gravity in de Sitter space

Energy Technology Data Exchange (ETDEWEB)

Cognola, Guido; Zerbini, Sergio [Universita di Trento (Italy); Istituto Nazionale di Fisica Nucleare Gruppo Collegato di Trento, Dipartimento di Fisica, Trento (Italy); Elizalde, Emilio [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Odintsov, Sergei D. [Consejo Superior de Investigaciones Cientificas (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Facultat Ciencies, Bellaterra (Barcelona) (Spain); ICREA, Barcelona (Spain); TSPU, Center of Theor. Phys., Tomsk (Russian Federation)

2009-12-15

We discuss the classical and quantum properties of non-local modified Gauss-Bonnet gravity in de Sitter space, using its equivalent representation via string-inspired local scalar-Gauss-Bonnet gravity with a scalar potential. A classical, multiple de Sitter universe solution is found where one of the de Sitter phases corresponds to the primordial inflationary epoch, while the other de Sitter space solution - the one with the smallest Hubble rate - describes the late-time acceleration of our universe. A Chameleon scenario for the theory under investigation is developed, and it is successfully used to show that the theory complies with gravitational tests. An explicit expression for the one-loop effective action for this non-local modified Gauss-Bonnet gravity in the de Sitter space is obtained. It is argued that this effective action might be an important step towards the solution of the cosmological constant problem. (orig.)

Spacetime structure of static solutions in Gauss-Bonnet gravity: Neutral case

International Nuclear Information System (INIS)

Torii, Takashi; Maeda, Hideki

2005-01-01

We study the spacetime structures of the static solutions in the n-dimensional Einstein-Gauss-Bonnet-Λ system systematically. We assume the Gauss-Bonnet coefficient α is non-negative and a cosmological constant is either positive, zero, or negative. The solutions have the (n-2)-dimensional Euclidean submanifold, which is the Einstein manifold with the curvature k=1, 0, and -1. We also assume 4α-tilde/l 2 ≤1, where l is the curvature radius, in order for the sourceless solution (M=0) to be defined. The general solutions are classified into plus and minus branches. The structures of the center, horizons, infinity, and the singular point depend on the parameters α, l 2 , k, M, and branches complicatedly so that a variety of global structures for the solutions are found. In our analysis, the M-tilde-r diagram is used, which makes our consideration clear and enables easy understanding by visual effects. In the plus branch, all the solutions have the same asymptotic structure at infinity as that in general relativity with a negative cosmological constant. For the negative-mass parameter, a new type of singularity called the branch singularity appears at nonzero finite radius r=r b >0. The divergent behavior around the singularity in Gauss-Bonnet gravity is milder than that around the central singularity in general relativity. There are three types of horizons: inner, black hole, and cosmological. In the k=1,0 cases, the plus-branch solutions do not have any horizon. In the k=-1 case, the radius of the horizon is restricted as r h h >√(2α-tilde)) in the plus (minus) branch. The black hole solution with zero or negative mass exists in the plus branch even for the zero or positive cosmological constant. There is also the extreme black hole solution with positive mass. We briefly discuss the effect of the Gauss-Bonnet corrections on black hole formation in a collider and the possibility of the violation of the third law of the black hole thermodynamics

Surgery: Modified Pi with Triple-Bonnet Flap and Fronto-Orbital Advancement.

Science.gov (United States)

Singh Raswan, Uday; Singh Chhiber, Sarbjit; Ramzan, Altaf Umar

2017-01-01

Craniosynostosis is the premature fusion of one or more of the cranial sutures and can occur as part of a syndrome or as an isolated defect. Pansynostosis is a rare form of craniosynostosis that involves premature fusion of all the cranial sutures (coronal, sagittal, metopic, and occipital). Particularly in cases of late presentation, there are heightened clinical concerns, both functional and aesthetic. In untreated cases of pansynostosis and increased intracranial pressure, optic nerve damage progresses to optic atrophy and then blindness. Cranial vault reconstruction is the standard surgical treatment. We attempt to highlight the importance of modifying the osteotomies and reshaping of the cranial vault based on individual requirements in order to achieve the best possible result and to prevent catastrophic blood loss. We present a case of modified pi with triple-bonnet flap and fronto-orbital advancement, an individual modification of the techniques of cranial vault reconstruction, in a patient with pansynostosis with optic atrophy. The technical variation can be applied to any case of pansynostosis requiring cranial vault reconstruction. © 2017 S. Karger AG, Basel.

Horizons of radiating black holes in Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Ghosh, S. G.; Deshkar, D. W.

2008-01-01

A Vaidya-based model of a radiating black hole is studied in a 5-dimensional Einstein gravity with Gauss-Bonnet contribution of quadratic curvature terms. The structure and locations of the apparent and event horizons of the radiating black hole are determined

Einstein-Gauss-Bonnet metrics: black holes, black strings and a staticity theorem

International Nuclear Information System (INIS)

Bogdanos, C.; Charmousis, C.; Gouteraux, B.; Zegers, R.

2009-01-01

We find the general solution of the 6-dimensional Einstein-Gauss-Bonnet equations in a large class of space and time-dependent warped geometries. Several distinct families of solutions are found, some of which include black string metrics, space and time-dependent solutions and black holes with exotic horizons. Among these, some are shown to verify a Birkhoff type staticity theorem, although here, the usual assumption of maximal symmetry on the horizon is relaxed, allowing exotic horizon geometries. We provide explicit examples of such static exotic black holes, including ones whose horizon geometry is that of a Bergman space. We find that the situation is very different from higher-dimensional general relativity, where Einstein spaces are admissible black hole horizons and the associated black hole potential is not even affected. In Einstein-Gauss-Bonnet theory, on the contrary, the non-trivial Weyl tensor of such exotic horizons is exposed to the bulk dynamics through the higher order Gauss-Bonnet term, severely constraining the allowed horizon geometries and adding a novel charge-like parameter to the black hole potential. The latter is related to the Euler characteristic of the four-dimensional horizon and provides, in some cases, additional black hole horizons.

Hydrogeologic characteristics of domains of sparsely fractured rock in the granitic Lac Du Bonnet Batholith, southeastern Manitoba, Canada

International Nuclear Information System (INIS)

Stevenson, D.R.; Kozak, E.T.; Davison, C.C.; Gascoyne, M.; Broadfoot, R.A.

1996-06-01

The hydrogeologic characteristics of the granitic Lac du Bonnet batholith in southeastern Manitoba have been studied since 1978, as part of AECL's program to assess the concept of disposing of Canada's nuclear fuel waste deep within plutonic rocks of the Canadian Shield (Davison et al. 1994a). These studies have included an extensive program of drilling, logging, testing, sampling and monitoring in 19 deep surface boreholes drilled at Grid areas located across the Lac du Bonnet batholith, at the Whiteshell Laboratory (WL), and in surface and underground boreholes at the Underground Research Laboratory (URL). Based on these investigations domains of low permeability, sparsely fractured rock (SFR) have been identified in the Lac du Bonnet batholith

Reduction of entanglement degradation in Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Nasr Esfahani, B.; Shamirzaie, M.; Soltani, M.

2011-01-01

Bipartite entanglement for states of a noninteracting bosonic or fermionic field in the spacetime of a spherically symmetric black hole of Einstein-Gauss-Bonnet gravity is investigated. Although the initial state is chosen to be maximally entangled as the Bell states, the Hawking-Unruh effect causes the state to be mixed and the entanglement degrades, but with different asymptotic behaviors for the fermionic and bosonic fields. The Gauss-Bonnet term with positive α can play an antigravitation role and so this causes a decrease in the Hawking-Unruh effect and consequently reduces the entanglement degradation. On the other hand, the suggested higher dimensions for the spacetime lead to increased entanglement degradation by increasing the dimension. There is a dramatic difference between the behaviors of the entanglement in terms of the radius of the horizon for a five-dimensional black hole and that for higher dimensional black holes. Both bosonic and fermionic fields entanglements are treated beyond the single-mode approximation. Also, the cases where the accelerating observers located at regions near and far from the event horizon of black hole are studied separately.

Early-life stress and the development of obesity and insulin resistance in juvenile bonnet macaques.

Science.gov (United States)

Kaufman, Daniel; Banerji, Mary Ann; Shorman, Igor; Smith, Eric L P; Coplan, Jeremy D; Rosenblum, Leonard A; Kral, John G

2007-05-01

Stress is a risk factor for chronic illnesses such as obesity, type 2 diabetes, and hypertension and has been postulated to cause the metabolic syndrome via perturbation of the hypothalamo-pituitary-adrenal (HPA) axis. In our model of early-life stress (variable foraging demand [VFD]), food insecurity is imposed on monkey mothers for 16 weeks beginning when their nursing offspring are 3-5 months of age. Under VFD, food availability is never restricted, and the infant's growth is unaffected. VFD rearing does, however, cause a range of neurobiological abnormalities, including dysregulation of the HPA axis, manifested in abnormal cerebrospinal fluid cortisol and corticotropin-releasing factor levels. We previously reported spontaneous occurrence of metabolic syndrome in 14% of normally reared peripubertal bonnet macaques given ad libitum access to standard monkey chow. Here, we show that compared with normally reared monkeys, peripubertal VFD juveniles exhibit greater weight, BMI, abdominal circumference, and glucagon-like peptide-1 and decreased glucose disposal rates during hyperinsulinemic-euglycemic clamps. Our data suggest that early-life stress during a critical period of neuro development can result in the peripubertal emergence of obesity and insulin resistance.

Finite-time future singularities in modified Gauss-Bonnet and F(R,G) gravity and singularity avoidance

International Nuclear Information System (INIS)

Bamba, Kazuharu; Odintsov, Sergei D.; Sebastiani, Lorenzo; Zerbini, Sergio

2010-01-01

We study all four types of finite-time future singularities emerging in the late-time accelerating (effective quintessence/phantom) era from F(R,G)-gravity, where R and G are the Ricci scalar and the Gauss-Bonnet invariant, respectively. As an explicit example of F(R,G)-gravity, we also investigate modified Gauss-Bonnet gravity, so-called F(G)-gravity. In particular, we reconstruct the F(G)-gravity and F(R,G)-gravity models where accelerating cosmologies realizing the finite-time future singularities emerge. Furthermore, we discuss a possible way to cure the finite-time future singularities in F(G)-gravity and F(R,G)-gravity by taking into account higher-order curvature corrections. The example of non-singular realistic modified Gauss-Bonnet gravity is presented. It turns out that adding such non-singular modified gravity to singular Dark Energy makes the combined theory a non-singular one as well. (orig.)

Holographic Van der Waals-like phase transition in the Gauss–Bonnet gravity

Energy Technology Data Exchange (ETDEWEB)

He, Song, E-mail: hesong17@gmail.com [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Golm (Germany); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Li-Fang, E-mail: lilf@itp.ac.cn [Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Zeng, Xiao-Xiong, E-mail: xxzeng@itp.ac.cn [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Material Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China)

2017-02-15

The Van der Waals-like phase transition is observed in temperature–thermal entropy plane in spherically symmetric charged Gauss–Bonnet–AdS black hole background. In terms of AdS/CFT, the non-local observables such as holographic entanglement entropy, Wilson loop, and two point correlation function of very heavy operators in the field theory dual to spherically symmetric charged Gauss–Bonnet–AdS black hole have been investigated. All of them exhibit the Van der Waals-like phase transition for a fixed charge parameter or Gauss–Bonnet parameter in such gravity background. Further, with choosing various values of charge or Gauss–Bonnet parameter, the equal area law and the critical exponent of the heat capacity are found to be consistent with phase structures in temperature–thermal entropy plane.

Anton's Syndrome due to Bilateral Ischemic Occipital Lobe Strokes.

Science.gov (United States)

Zukić, Sanela; Sinanović, Osman; Zonić, Lejla; Hodžić, Renata; Mujagić, Svjetlana; Smajlović, Edina

2014-01-01

We present a case of a patient with Anton's syndrome (i.e., visual anosognosia with confabulations), who developed bilateral occipital lobe infarct. Bilateral occipital brain damage results in blindness, and patients start to confabulate to fill in the missing sensory input. In addition, the patient occasionally becomes agitated and talks to himself, which indicates that, besides Anton's syndrome, he might have had Charles Bonnet syndrome, characterized by both visual loss and hallucinations. Anton syndrome, is not so frequent condition and is most commonly caused by ischemic stroke. In this particular case, the patient had successive bilateral occipital ischemia as a result of massive stenoses of head and neck arteries.

General aspects of Gauss-Bonnet models without potential in dimension four

Energy Technology Data Exchange (ETDEWEB)

Santillán, Osvaldo P., E-mail: firenzecita@hotmail.com [Departamento de Matemáticas Luis Santaló (IMAS), Buenos Aires (Argentina)

2017-07-01

In the present work, the isotropic and homogenous solutions with spatial curvature k =0 of four dimensional Gauss-Bonnet models are characterized. The main assumption is that the scalar field φ which is coupled to the Gauss-Bonnet term has no potential [1]–[2]. Some singular and some eternal solutions are described. The evolution of the universe is given in terms of a curve γ=( H (φ), φ) which is the solution of a polynomial equation P ( H {sup 2}, φ)=0 with φ dependent coefficients. In addition, it is shown that the initial conditions in these models put several restrictions on the evolution. For instance, an universe initially contracting will be contracting always for future times and an universe that is expanding was always expanding at past times. Thus, there are no cyclic cosmological solutions for this model. These results are universal, that is, independent on the form of the coupling f (φ) between the scalar field and the Gauss-Bonnet term. In addition, a proof that at a turning point φ-dot →0 a singularity necessarily emerges is presented, except for some specific choices of the coupling. This is valid unless the Hubble constant H → 0 at this point. This proof is based on the Raychaudhuri equation for the model. The description presented here is in part inspired in the works [3]–[4]. However, the mathematical methods that are implemented are complementary of those in these references, and they may be helpful for study more complicated situations in a future.

The effect of the Gauss-Bonnet term on Hawking radiation from arbitrary dimensional black brane

International Nuclear Information System (INIS)

Kuang, Xiao-Mei; Saavedra, Joel; Oevguen, Ali

2017-01-01

We investigate the probabilities of the tunneling and the radiation spectra of massive spin-1 particles from arbitrary dimensional Gauss-Bonnet-Axions (GBA) Anti-de Sitter (AdS) black branes, via using the WKB approximation to the Proca spin-1 field equation. The tunneling probabilities and Hawking temperature of the arbitrary dimensional GBA AdS black brane is calculated via the Hamilton-Jacobi approach. We also compute the Hawking temperature via the Parikh-Wilczek tunneling approach. The results obtained from the two methods are consistent. In our setup, the Gauss-Bonnet (GB) coupling affects the Hawking temperature if and only if the momentum of the axion fields is non-vanishing. (orig.)

The effect of the Gauss-Bonnet term on Hawking radiation from arbitrary dimensional black brane

Energy Technology Data Exchange (ETDEWEB)

Kuang, Xiao-Mei [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Yangzhou University, Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou (China); Saavedra, Joel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Oevguen, Ali [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Eastern Mediterranean University, Physics Department, Famagusta, Northern Cyprus (Country Unknown)

2017-09-15

We investigate the probabilities of the tunneling and the radiation spectra of massive spin-1 particles from arbitrary dimensional Gauss-Bonnet-Axions (GBA) Anti-de Sitter (AdS) black branes, via using the WKB approximation to the Proca spin-1 field equation. The tunneling probabilities and Hawking temperature of the arbitrary dimensional GBA AdS black brane is calculated via the Hamilton-Jacobi approach. We also compute the Hawking temperature via the Parikh-Wilczek tunneling approach. The results obtained from the two methods are consistent. In our setup, the Gauss-Bonnet (GB) coupling affects the Hawking temperature if and only if the momentum of the axion fields is non-vanishing. (orig.)

5D black hole solution in Einstein-Yang-Mills-Gauss-Bonnet theory

International Nuclear Information System (INIS)

Mazharimousavi, S. Habib; Halilsoy, M.

2007-01-01

By adopting the 5D version of the Wu-Yang ansatz we present in closed form a black hole solution in the Einstein-Yang-Mills-Gauss-Bonnet theory. In the Einstein-Yang-Mills limit, we recover the 5D black hole solution already known

Anton’s Syndrome due to Bilateral Ischemic Occipital Lobe Strokes

Directory of Open Access Journals (Sweden)

Sanela Zukić

2014-01-01

Full Text Available We present a case of a patient with Anton’s syndrome (i.e., visual anosognosia with confabulations, who developed bilateral occipital lobe infarct. Bilateral occipital brain damage results in blindness, and patients start to confabulate to fill in the missing sensory input. In addition, the patient occasionally becomes agitated and talks to himself, which indicates that, besides Anton’s syndrome, he might have had Charles Bonnet syndrome, characterized by both visual loss and hallucinations. Anton syndrome, is not so frequent condition and is most commonly caused by ischemic stroke. In this particular case, the patient had successive bilateral occipital ischemia as a result of massive stenoses of head and neck arteries.

Black-hole solutions with scalar hair in Einstein-scalar-Gauss-Bonnet theories

Science.gov (United States)

Antoniou, G.; Bakopoulos, A.; Kanti, P.

2018-04-01

In the context of the Einstein-scalar-Gauss-Bonnet theory, with a general coupling function between the scalar field and the quadratic Gauss-Bonnet term, we investigate the existence of regular black-hole solutions with scalar hair. Based on a previous theoretical analysis, which studied the evasion of the old and novel no-hair theorems, we consider a variety of forms for the coupling function (exponential, even and odd polynomial, inverse polynomial, and logarithmic) that, in conjunction with the profile of the scalar field, satisfy a basic constraint. Our numerical analysis then always leads to families of regular, asymptotically flat black-hole solutions with nontrivial scalar hair. The solution for the scalar field and the profile of the corresponding energy-momentum tensor, depending on the value of the coupling constant, may exhibit a nonmonotonic behavior, an unusual feature that highlights the limitations of the existing no-hair theorems. We also determine and study in detail the scalar charge, horizon area, and entropy of our solutions.

Fractionated x-radiation damage to developing ovaries in the Bonnet Monkey (Macaca radiata)

International Nuclear Information System (INIS)

Andersen, A.C.; Hendrickx, A.G.; Momeni, M.H.

1977-01-01

Fractionated x-ray exposures of 11.5 rad each (total 200 rad) given twice weekly between 77 and 133 days postcoitum severely damaged the ovaries of eight out of nine fetal bonnet monkeys. This radiation regimen reduced follicle counts by 75% or more

A geological reconnaissance study of the Lac du Bonnet batholith

International Nuclear Information System (INIS)

Tammemagi, H.Y.; Kerford, P.S.; Requeima, J.C.; Temple, C.A.

1980-02-01

A geological reconnaissance survey was carried out of the Lac du Bonnet batholith, southeastern Manitoba, as part of the concept verification phase of the nuclear fuel waste disposal program for Canada. This report summarizes available geological information, presents the results of field mapping and discusses the geochemical analyses of rock samples. The geological and structural aspects of the batholith are described as well as its regional setting and possible genesis. (auth)

Colliding scalar pulses in the Einstein-Gauss-Bonnet gravity

Directory of Open Access Journals (Sweden)

Shinkai Hisaaki

2018-01-01

Full Text Available We numerically investigated how the nonlinear dynamics depends on the dimensionality and on the higher-order curvature corrections in the form of Gauss-Bonnet (GB terms, with a model of colliding scalar pulses in plane-symmetric space-time. We observed that a collision of large scalar pulses will produce a large-curvature region, of which the magnitude depends on αGB. The normal corrections (αGB > 0 work for avoiding the appearance of singularity, although it is inevitable.

In vivo and in vitro attenuation of naloxone-precipitated experimental opioid withdrawal syndrome by insulin and selective KATP channel modulator.

Science.gov (United States)

Singh, Prabhat; Sharma, Bhupesh; Gupta, Surbhi; Sharma, B M

2015-01-01

Opiate exposure for longer duration develops state of dependence in humans and animals, which is revealed by signs and symptoms of withdrawal precipitated by opioid receptor antagonists. The sudden withdrawal of opioids produces a withdrawal syndrome in opioid-dependent subjects. Insulin and ATP-sensitive potassium (KATP) channel-mediated glucose homeostasis have been shown to modulate morphine withdrawal. Present study has been structured to investigate the role of insulin and pharmacological modulator of KATP channel (gliclazide) in experimental morphine withdrawal syndrome, both invivo and invitro. In this study, naloxone-precipitated morphine withdrawal syndrome in mice (invivo) as well as in rat ileum (invitro) were utilized to assess opioid withdrawal phenomenon. Morphine withdrawal syndromes like jumping and rearing frequency, forepaw licking, circling, fore paw tremor, wet dog shake, sneezing, overall morphine withdrawal severity (OMWS), serum glucose, brain malondialdehyde (MDA), glutathione (GSH), nitrite/nitrate, and calcium (Ca(+2)) were assessed. Naloxone has significantly increased morphine withdrawal syndrome, both invivo and invitro. Insulin and gliclazide have significantly attenuated, naloxone induced behavioral changes like jumping and rearing frequency, forepaw licking, wet dog shake, sneezing, straightening, circling, OMWS, and various biochemical impairments such as serum glucose, brain MDA, GSH, nitrite/nitrate, and Ca(+2) in morphine-dependent animals (invivo). In vitro, insulin and gliclazide have significantly reduced naloxone-induced contraction in morphine-withdrawn rat ileum preparation. Insulin and gliclazide (KATP channel blocker) have attenuated naloxone-precipitated morphine withdrawal syndrome, both invivo and invitro. Thus, insulin and KATP channel modulation may provide new avenues for research in morphine withdrawal.

Reconstruction of the Scalar Field Potential in Inflationary Models with a Gauss-Bonnet term

Science.gov (United States)

Koh, Seoktae; Lee, Bum-Hoon; Tumurtushaa, Gansukh

2017-06-01

We consider inflationary models with a Gauss-Bonnet term to reconstruct the scalar-field potentials and the Gauss-Bonnet coupling functions. Both expressions are derived from the observationally favored configurations of ns and r . Our result implies that, for the reconstructed potentials and coupling functions, the blue tilt of inflationary tensor fluctuations can be realized. To achieve a blue tilt for the inflationary tensor fluctuations, a scalar field must climb up its potential before rolling down. We further investigate the properties of propagation of the perturbation modes in Friedmann-Robertson-Walker spacetime. For the reconstructed configurations that give rise to the blue tilt for the inflationary tensor fluctuations, we show that the ghosts and instabilities are absent with the superluminal propagation speeds for the scalar perturbation modes, whereas the propagation speeds of the tensor perturbations are subluminal.

Scalar hair around charged black holes in Einstein-Gauss-Bonnet gravity

Science.gov (United States)

Grandi, Nicolás; Landea, Ignacio Salazar

2018-02-01

We explore charged black hole solutions in Einstein-Gauss-Bonnet gravity in five dimensions, with a charged scalar hair. We interpret such hairy black holes as the final state of the superradiant instability previously reported for this system. We explore the relation of the hairy black hole solutions with the nonbackreacting quasibound states and scalar clouds, as well as with the boson star solutions.

Kink-antikink, trapping bags and five-dimensional Gauss-Bonnet gravity

OpenAIRE

Giovannini, Massimo

2006-01-01

Five-dimensional Gauss-Bonnet gravity, with one warped extra-dimension, allows classes of solutions where two scalar fields combine either in a kink-antikink system or in a trapping bag configuration. While the kink-antikink system can be interpreted as a pair of gravitating domain walls with opposite topological charges, the trapping bag solution consists of a domain wall supplemented by a non-topological defect. In both classes of solutions, for large absolute values of the bulk coordinate ...

New higher-derivative invariants in N=2 supergravity and the Gauss-Bonnet term

NARCIS (Netherlands)

Butter, D.; de Wit, B.; Kuzenko, S.M.; Lodato, I.|info:eu-repo/dai/nl/357520890

2013-01-01

A new class of N = 2 locally supersymmetric higher-derivative invariants is constructed based on logarithms of conformal primary chiral superfields. They characteristically involve a coupling to Rμν 2 − 1 3 R2, which equals the non-conformal part of the Gauss-Bonnet term. Upon combining one such

Cosmological dynamics of spatially flat Einstein-Gauss-Bonnet models in various dimensions: high-dimensional Λ-term case

Energy Technology Data Exchange (ETDEWEB)

Pavluchenko, Sergey A. [Universidade Federal do Maranhao (UFMA), Programa de Pos-Graduacao em Fisica, Sao Luis, Maranhao (Brazil)

2017-08-15

In this paper we perform a systematic study of spatially flat [(3+D)+1]-dimensional Einstein-Gauss-Bonnet cosmological models with Λ-term. We consider models that topologically are the product of two flat isotropic subspaces with different scale factors. One of these subspaces is three-dimensional and represents our space and the other is D-dimensional and represents extra dimensions. We consider no ansatz of the scale factors, which makes our results quite general. With both Einstein-Hilbert and Gauss-Bonnet contributions in play, D = 3 and the general D ≥ 4 cases have slightly different dynamics due to the different structure of the equations of motion. We analytically study the equations of motion in both cases and describe all possible regimes with special interest on the realistic regimes. Our analysis suggests that the only realistic regime is the transition from high-energy (Gauss-Bonnet) Kasner regime, which is the standard cosmological singularity in that case, to the anisotropic exponential regime with expanding three and contracting extra dimensions. Availability of this regime allows us to put a constraint on the value of Gauss-Bonnet coupling α and the Λ-term - this regime appears in two regions on the (α, Λ) plane: α < 0, Λ > 0, αΛ ≤ -3/2 and α > 0, αΛ ≤ (3D{sup 2} - 7D + 6)/(4D(D-1)), including the entire Λ < 0 region. The obtained bounds are confronted with the restrictions on α and Λ from other considerations, like causality, entropy-to-viscosity ratio in AdS/CFT and others. Joint analysis constrains (α, Λ) even further: α > 0, D ≥ 2 with (3D{sup 2} - 7D + 6)/(4D(D-1)) ≥ αΛ ≥ -(D+2)(D+3)(D{sup 2} + 5D + 12)/(8(D{sup 2} + 3D + 6){sup 2}). (orig.)

Quasinormal modes of Gauss-Bonnet-AdS black holes: towards holographic description of finite coupling

Science.gov (United States)

Konoplya, R. A.; Zhidenko, A.

2017-09-01

Here we shall show that there is no other instability for the Einstein-Gauss-Bonnet-anti-de Sitter (AdS) black holes, than the eikonal one and consider the features of the quasinormal spectrum in the stability sector in detail. The obtained quasinormal spectrum consists from the two essentially different types of modes: perturbative and non-perturbative in the Gauss-Bonnet coupling α. The sound and hydrodynamic modes of the perturbative branch can be expressed through their Schwazrschild-AdS limits by adding a linear in α correction to the damping rates: ω≈Re ω SAdS -Im ω SAdS(1- α·(( D+1)( D-4) /2 R 2)) i, where R is the AdS radius. The non-perturbative branch of modes consists of purely imaginary modes, whose damping rates unboundedly increase when α goes to zero. When the black hole radius is much larger than the anti-de Sitter radius R, the regime of the black hole with planar horizon (black brane) is reproduced. If the Gauss-Bonnet coupling α (or used in holography λGB) is not small enough, then the black holes and branes suffer from the instability, so that the holographic interpretation of perturbation of such black holes becomes questionable, as, for example, the claimed viscosity bound violation in the higher derivative gravity. For example, D = 5 black brane is unstable at |λGB| > 1 /8 and has anomalously large relaxation time when approaching the threshold of instability.

NONSINGULAR UNIVERSES IN GAUSS–BONNET GRAVITY’S RAINBOW

International Nuclear Information System (INIS)

Hendi, Seyed Hossein; Momennia, Mehrab; Panah, Behzad Eslam; Faizal, Mir

2016-01-01

In this paper, we study the rainbow deformation of Friedmann-Robertson-Walker (FRW) cosmology in both Einstein gravity and Gauss–Bonnet (GB) gravity. We demonstrate that the singularity in FRW cosmology can be removed because of the rainbow deformation of the FRW metric. We obtain the general constraints required for FRW cosmology to be free of singularities. We observe that the inclusion of GB gravity can significantly change the constraints required to obtain nonsingular universes. We use rainbow functions motivated by the hard spectra of gamma-ray bursts to deform FRW cosmology and explicitly demonstrate that such a deformation removes the singularity in FRW cosmology.

NONSINGULAR UNIVERSES IN GAUSS–BONNET GRAVITY’S RAINBOW

Energy Technology Data Exchange (ETDEWEB)

Hendi, Seyed Hossein; Momennia, Mehrab; Panah, Behzad Eslam [Physics Department and Biruni Observatory, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Faizal, Mir [Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada)

2016-08-20

In this paper, we study the rainbow deformation of Friedmann-Robertson-Walker (FRW) cosmology in both Einstein gravity and Gauss–Bonnet (GB) gravity. We demonstrate that the singularity in FRW cosmology can be removed because of the rainbow deformation of the FRW metric. We obtain the general constraints required for FRW cosmology to be free of singularities. We observe that the inclusion of GB gravity can significantly change the constraints required to obtain nonsingular universes. We use rainbow functions motivated by the hard spectra of gamma-ray bursts to deform FRW cosmology and explicitly demonstrate that such a deformation removes the singularity in FRW cosmology.

The ability of flexible car bonnets to mitigate the consequences of frontal impact with pedestrians

Science.gov (United States)

Stanisławek, Sebastian; Niezgoda, Tadeusz

2018-01-01

The paper presents the results of numerical research on a vehicle representing a Toyota Yaris passenger sedan hitting a pedestrian. A flexible car body is suggested as an interesting way to increase safety. The authors present a simple low-cost bonnet buffer concept that may mitigate the effects of frontal impact. Computer simulation was the method chosen to solve the problem efficiently. The Finite Element Method (FEM) implemented in the LS-DYNA commercial code was used. The testing procedure was based on the Euro NCAP protocol. A flexible bonnet buffer shows its usefulness in preventing casualties in typical accidents. In the best scenario, the HIC15 parameter is only 380 when such a buffer is installed. In comparison, an accident involving a car without any protection produces an HIC15 of 970, which is very dangerous for pedestrians.

Thermodynamics of the Maxwell-Gauss-Bonnet anti-de Sitter black hole with higher derivative gauge corrections

International Nuclear Information System (INIS)

Anninos, Dionysios; Pastras, Georgios

2009-01-01

The local and global thermal phase structure for asymptotically anti-de Sitter black holes charged under an abelian gauge group, with both Gauss-Bonnet and quartic field strength corrections, is mapped out for all parameter space. We work in the grand canonical ensemble where the external electric potential is held fixed. The analysis is performed in an arbitrary number of dimensions, for all three possible horizon topologies - spherical, flat or hyperbolic. For spherical horizons, new metastable configurations are exhibited both for the pure Gauss-Bonnet theory as well as the pure higher derivative gauge theory and combinations thereof. In the pure Gauss-Bonnet theory with negative coefficient and five or more spatial dimensions, two locally thermally stable black hole solutions are found for a given temperature. Either one or both of them may be thermally favored over the anti-de Sitter vacuum - corresponding to a single or a double decay channel for the metastable black hole. Similar metastable configurations are uncovered for the theory with pure quartic field strength corrections, as well combinations of the two types of corrections, in three or more spatial dimensions. Finally, a secondary Hawking-Page transition between the smaller thermally favored black hole and thermal anti-de Sitter space is observed when both corrections are turned on and their couplings are both positive.

On the Chern-Gauss-Bonnet theorem for the noncommutative 4-sphere

Science.gov (United States)

Arnlind, Joakim; Wilson, Mitsuru

2017-01-01

We construct a differential calculus over the noncommutative 4-sphere in the framework of pseudo-Riemannian calculi, and show that for every metric in a conformal class of perturbations of the round metric, there exists a unique metric and torsion-free connection. Furthermore, we find a localization of the projective module corresponding to the space of vector fields, which allows us to formulate a Chern-Gauss-Bonnet type theorem for the noncommutative 4-sphere.

Area and Entropy Spectrum of Gauss—Bonnet Gravity in de Sitter Space-Times for Black Hole Event Horizon

International Nuclear Information System (INIS)

Chen Qiang; Ren Ji-Rong

2013-01-01

In this paper, we use the modified Hod's treatment and the Kunstatter's method to study the horizon area spectrum and entropy spectrum in Gauss—Bonnet de-Sitter space-time, which is regarded as the natural generalization of Einstein gravity by including higher derivative correction terms to the original Einstein—Hilbert action. The horizon areas have some properties that are very different from the vacuum solutions obtained from the frame of Einstein gravity. With the new physical interpretation of quasinormal modes, the area/entropy spectrum for the event horizon for near-extremal Gauss—Bonnet de Sitter black holes are obtained. Meanwhile, we also extend the discussion of area/entropy quantization to the non-extremal black holes solutions. (general)

Visual hallucinatory syndromes and the anatomy of the visual brain.

Science.gov (United States)

Santhouse, A M; Howard, R J; ffytche, D H

2000-10-01

We have set out to identify phenomenological correlates of cerebral functional architecture within Charles Bonnet syndrome (CBS) hallucinations by looking for associations between specific hallucination categories. Thirty-four CBS patients were examined with a structured interview/questionnaire to establish the presence of 28 different pathological visual experiences. Associations between categories of pathological experience were investigated by an exploratory factor analysis. Twelve of the pathological experiences partitioned into three segregated syndromic clusters. The first cluster consisted of hallucinations of extended landscape scenes and small figures in costumes with hats; the second, hallucinations of grotesque, disembodied and distorted faces with prominent eyes and teeth; and the third, visual perseveration and delayed palinopsia. The three visual psycho-syndromes mirror the segregation of hierarchical visual pathways into streams and suggest a novel theoretical framework for future research into the pathophysiology of neuropsychiatric syndromes.

Reversible cerebral vasoconstriction syndrome precipitated by airplane descent: Case report.

Science.gov (United States)

Hiraga, Akiyuki; Aotsuka, Yuya; Koide, Kyosuke; Kuwabara, Satoshi

2017-10-01

Background Reversible cerebral vasoconstriction syndrome (RCVS) is characterized by segmental vasospasm. Vasoactive agents and childbirth have been reported as precipitating factors for RCVS; however, RCVS induced by altitude change or air travel has rarely been reported. Case We present a case of a 74-year-old woman who presented with thunderclap headache during airplane descent. Magnetic resonance angiography demonstrated segmental vasoconstriction that improved 9 days after onset. Conclusion These findings indicate that airplane descent may be a trigger of RCVS. The time course of headache in the present case was similar to that of prolonged headache attributed to airplane travel, indicating that RCVS during air travel may have previously been overlooked and that some headache attributed to airplane travel cases may represent a milder form of RCVS.

Nambu-Goto string with the Gauss-Bonnet term and point-like masses at the ends

Science.gov (United States)

Hadasz, Leszek; Róg, Tomasz

1996-02-01

We investigate classical dynamics of the Nambu-Goto string with Gauss-Bonnet term in the action and point-like masses at the ends in the context of effective QCD string. The configuration of rigidly rotating string is studied and its application to phenomenological description of meson spectroscopy is discussed.

Gauss–Bonnet cosmology with induced gravity and a non-minimally coupled scalar field on the brane

International Nuclear Information System (INIS)

Nozari, Kourosh; Fazlpour, Behnaz

2008-01-01

We construct a cosmological model with a non-minimally coupled scalar field on the brane, where Gauss–Bonnet and induced gravity effects are taken into account. This model has 5D character at both high and low energy limits but reduces to 4D gravity for intermediate scales. While induced gravity is a manifestation of the IR limit of the model, the Gauss–Bonnet term and non-minimal coupling of the scalar field and induced gravity are essentially related to the UV limit of the scenario. We study the cosmological implications of this scenario focusing on the late time behavior of the solutions. In this setup, non-minimal coupling plays the role of an additional fine-tuning parameter that controls the initial density of the predicted finite density big bang. Also, non-minimal coupling has important implications for the bouncing nature of the solutions

Black holes, parallelizable horizons, and half-BPS states for the Einstein-Gauss-Bonnet theory in five dimensions

International Nuclear Information System (INIS)

Canfora, Fabrizio; Giacomini, Alex; Troncoso, Ricardo

2008-01-01

Exact vacuum solutions with a nontrivial torsion for the Einstein-Gauss-Bonnet theory in five dimensions are constructed. We consider a class of static metrics whose spacelike section is a warped product of the real line with a nontrivial base manifold endowed with a fully antisymmetric torsion. It is shown that requiring solutions of this sort to exist, fixes the Gauss-Bonnet coupling such that the Lagrangian can be written as a Chern-Simons form. The metric describes black holes with an arbitrary, but fixed, base manifold. It is shown that requiring its ground state to possess unbroken supersymmetries fixes the base manifold to be locally a parallelized three-sphere. The ground state turns out to be half-BPS, which could not be achieved in the absence of torsion in vacuum. The Killing spinors are explicitly found

Kink-antikink, trapping bags and five-dimensional Gauss-Bonnet gravity

CERN Document Server

Giovannini, Massimo

2006-01-01

Five-dimensional Gauss-Bonnet gravity, with one warped extra-dimension, allows classes of solutions where two scalar fields combine either in a kink-antikink system or in a trapping bag configuration. While the kink-antikink system can be interpreted as a pair of gravitating domain walls with opposite topological charges, the trapping bag solution consists of a domain wall supplemented by a non-topological defect. In both classes of solutions, for large absolute values of the bulk coordinate (i.e. far from the core of the defects), the geometry is given by five-dimensional anti-de Sitter space.

Instability of black holes with a Gauss-Bonnet term

International Nuclear Information System (INIS)

Ahn, Wha-Keun; Gwak, Bogeun; Lee, Wonwoo; Lee, Bum-Hoon

2015-01-01

We investigate the fragmentation instability of hairy black holes in the theory with a Gauss-Bonnet (GB) term in asymptotically flat spacetime. Our approach is through the non-perturbative fragmentation instability. By this approach, we investigate whether the initial black hole can be broken into two black holes by comparing the entropy of the initial black hole with the sum of those of two fragmented black holes. The relation between the black hole instability and the GB coupling with dilaton hair are presented. We describe the phase diagrams with respect to the mass of the black hole solutions and coupling constants. We find that a perturbatively stable black hole can be unstable under fragmentation. (orig.)

Hydrodynamics dual to Einstein-Gauss-Bonnet gravity: all-order gradient resummation

Energy Technology Data Exchange (ETDEWEB)

Bu, Yanyan; Lublinsky, Michael; Sharon, Amir [Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

2015-06-24

Relativistic hydrodynamics dual to Einstein-Gauss-Bonnet gravity in asymptotic AdS{sub 5} space is under study. To linear order in the amplitude of the fluid velocity and temperature, we derive the fluid’s stress-energy tensor via an all-order resummation of the derivative terms. Each order is accompanied by new transport coefficients, which all together could be compactly absorbed into two functions of momenta, referred to as viscosity functions. Via inverse Fourier transform, these viscosities appear as memory functions in the constitutive relation between components of the stress-energy tensor.

78 FR 61003 - Endangered and Threatened Wildlife and Plants; Endangered Species Status for the Florida Bonneted...

Science.gov (United States)

2013-10-02

... development and agriculture have impacted the Florida bonneted bat and are expected to further curtail its... birth and leave young in the roost while they make multiple foraging excursions to support lactation... appear in spring and summer, generally with only one or two births within the colony per year (S. Trokey...

Management of precipitated opiate withdrawal syndrome induced by nalmefene mistakenly prescribed in opiate-dependent patients: a review for clinicians.

Science.gov (United States)

Franchitto, Nicolas; Jullian, Benedicte; Salles, Juliette; Pelissier, Fanny; Rolland, Benjamin

2017-06-01

Nalmefene, a long-acting µ-opioid antagonist approved to treat alcohol use disorder, is occasionally mistakenly prescribed to opiate-dependent or opioid-treated patients. We review recent literature on drug-drug interactions between nalmefene and opioids that lead to precipitated opioid withdrawal, and focus on its management and planning for care at discharge. Areas covered: This article provides a brief and comprehensive review of management of precipitated opioid withdrawal syndrome when nalmefene is associated with an opioid, whether misused or legally prescribed. Expert opinion: When treating an opiate-dependent patient with co-occurring alcohol use disorder, both conditions need to be a focus of clinical attention. New drugs for alcohol use disorder have been approved, but must be given cautiously and with a full understanding of their potential drug-drug interactions with opioid medications. Opiate-dependent patients should be intensively monitored for risk factors of alcohol use disorder and should be continuously motivated for treatment maintenance. When nalmefene is administered to opiate-dependent patients, acute opioid withdrawal syndrome may occur. Management of precipitated acute opioid withdrawal may include short or long-acting µ-opioid agonists during hospitalization, in addition to supportive treatment. The best management of polydrug abusers is based on a multidisciplinary approach, which should be pursued and improved through continuing medical education.

Phantom-like behavior of a DGP-inspired Scalar-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Nozari, Kourosh; Azizi, Tahereh; Setare, M.R.

2009-01-01

We study the phantom-like behavior of a DGP-inspired braneworld scenario where curvature correction on the brane is taken into account. We include a possible modification of the induced gravity on the brane by incorporating higher order curvature terms of Gauss-Bonnet type. We investigate the cosmological implications of the model and we show that the normal branch of the scenario self-accelerates in this modified scenario without introducing any dark energy component. Also, a phantom-like behavior can be realized in this model without introducing any phantom field that suffers from serious difficulties such as violation of the null energy condition

Casimir Energy of the Nambu-Goto String with Gauss-Bonnet Term and Point-Like Masses at the Ends

Science.gov (United States)

Hadasz, Leszek

1999-09-01

We calculate the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. This energy turns out to be negative for every values of the parameters of the model.

Casimir Energy of the Nambu-Goto String with Gauss-Bonnet Term and Point-Like Masses at the Ends

International Nuclear Information System (INIS)

Hadasz, L.

1999-01-01

We calculate the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. This energy turns out to be negative for every values of the parameters of the model. (author)

Some exact solutions with torsion in 5D Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Canfora, F.; Giacomini, A.; Willison, S.

2007-01-01

Exact solutions with torsion in Einstein-Gauss-Bonnet gravity are derived. These solutions have a cross product structure of two constant curvature manifolds. The equations of motion give a relation for the coupling constants of the theory in order to have solutions with nontrivial torsion. This relation is not the Chern-Simons combination. One of the solutions has an AdS 2 xS 3 structure and is so the purely gravitational analogue of the Bertotti-Robinson space-time where the torsion can be seen as the dual of the covariantly constant electromagnetic field

Ricci-Gauss-Bonnet holographic dark energy

Science.gov (United States)

Saridakis, Emmanuel N.

2018-03-01

We present a model of holographic dark energy in which the infrared cutoff is determined by both the Ricci and the Gauss-Bonnet invariants. Such a construction has the significant advantage that the infrared cutoff, and consequently the holographic dark energy density, does not depend on the future or the past evolution of the universe, but only on its current features, and moreover it is determined by invariants, whose role is fundamental in gravitational theories. We extract analytical solutions for the behavior of the dark energy density and equation-of-state parameters as functions of the redshift. These reveal the usual thermal history of the universe, with the sequence of radiation, matter and dark energy epochs, resulting in the future to a complete dark energy domination. The corresponding dark energy equation-of-state parameter can lie in the quintessence or phantom regime, or experience the phantom-divide crossing during the cosmological evolution, and its asymptotic value can be quintessencelike, phantomlike, or be exactly equal to the cosmological-constant value. Finally, we extract the constraints on the model parameters that arise from big bang nucleosynthesis.

Spontaneous Scalarization of Black Holes and Compact Stars from a Gauss-Bonnet Coupling.

Science.gov (United States)

Silva, Hector O; Sakstein, Jeremy; Gualtieri, Leonardo; Sotiriou, Thomas P; Berti, Emanuele

2018-03-30

We identify a class of scalar-tensor theories with coupling between the scalar and the Gauss-Bonnet invariant that exhibit spontaneous scalarization for both black holes and compact stars. In particular, these theories formally admit all of the stationary solutions of general relativity, but these are not dynamically preferred if certain conditions are satisfied. Remarkably, black holes exhibit scalarization if their mass lies within one of many narrow bands. We find evidence that scalarization can occur in neutron stars as well.

Casimir energy of the Nambu-Goto string with Gauss-Bonnet term and point-like masses at the ends

OpenAIRE

Hadasz, Leszek

1999-01-01

We calculate (using zeta function regularization) the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. The resulting value turns out to be negative for all values of the parameters of the model.

Ghosts in the self-accelerating DGP branch with Gauss–Bonnet effect

Energy Technology Data Exchange (ETDEWEB)

Liu, Yen-Wei; Izumi, Keisuke; Bouhmadi-López, Mariam; Chen, Pisin

2015-06-01

The Dvali–Gabadadze–Porrati brane-world model provides a possible approach to address the late-time cosmic acceleration. However, it has subsequently been pointed out that a ghost instability will arise on the self-accelerating branch. Here, we carefully investigate whether this ghost problem could be possibly cured by introducing the Gauss–Bonnet term in the five-dimensional bulk action, a natural generalization to the Dvali–Gabadadze–Porrati model. Our analysis is carried out for a background where a de Sitter brane is embedded in an anti–de Sitter bulk. Our result shows that the ghost excitations cannot be avoided even in this modified model.

Effects of salinity variations on CODAR ranges during the 2016 Bonnet Carré Spillway Opening

Science.gov (United States)

Howden, S. D.; Diercks, A. R.; Hode, L. E.; Cambazoglu, M. K.; Martin, K. M.

2017-12-01

On January 10, 2016 the Bonnet Carré Spillway was opened to relieve flooding on the Mississippi River, diverting river water into Lake Pontchartrain and then through the western Mississippi Sound. As part of the response to understand the effects of the spillway opening on the Mississippi Sound, a pair of 25 MHz CODAR SeaSondes were deployed on the coast of the western Mississippi Sound to monitor surface currents. This presented the additional opportunity to run a natural experiment on the effect of salinity on the range of CODAR signals. During the spillway event, salinities in the CODAR coverage area, as measured by monitoring stations operated by a partnership between the Mississippi Department of Marine Resources and the United States Geological Survey in the Sound ranged from over 30 to less than 2. Ranges from the CODAR stations were significantly correlated with these salinities. Additionally, the Naval Coastal Ocean Model output, run with real-time river input plus the Bonnet Carré Spillway freshwater input, was available for the analyzes for the spillway event time frame. The observations and modeling were used to investigate the role of salinity on SeaSonde range and how well those variations agree with theory.

Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories.

Science.gov (United States)

Antoniou, G; Bakopoulos, A; Kanti, P

2018-03-30

We consider a general Einstein-scalar-Gauss-Bonnet theory with a coupling function f(ϕ). We demonstrate that black-hole solutions appear as a generic feature of this theory since a regular horizon and an asymptotically flat solution may be easily constructed under mild assumptions for f(ϕ). We show that the existing no-hair theorems are easily evaded, and a large number of regular black-hole solutions with scalar hair are then presented for a plethora of coupling functions f(ϕ).

Evasion of No-Hair Theorems and Novel Black-Hole Solutions in Gauss-Bonnet Theories

Science.gov (United States)

Antoniou, G.; Bakopoulos, A.; Kanti, P.

2018-03-01

We consider a general Einstein-scalar-Gauss-Bonnet theory with a coupling function f (ϕ ) . We demonstrate that black-hole solutions appear as a generic feature of this theory since a regular horizon and an asymptotically flat solution may be easily constructed under mild assumptions for f (ϕ ). We show that the existing no-hair theorems are easily evaded, and a large number of regular black-hole solutions with scalar hair are then presented for a plethora of coupling functions f (ϕ ).

Is there a relation between the 2D Causal Set action and the Lorentzian Gauss-Bonnet theorem?

Science.gov (United States)

Benincasa, Dionigi M. T.

2011-07-01

We investigate the relation between the two dimensional Causal Set action, Script S, and the Lorentzian Gauss-Bonnet theorem (LGBT). We give compelling reasons why the answer to the title's question is no. In support of this point of view we calculate the causal set inspired action of causal intervals in some two dimensional spacetimes: Minkowski, the flat cylinder and the flat trousers.

Is there a relation between the 2D Causal Set action and the Lorentzian Gauss-Bonnet theorem?

International Nuclear Information System (INIS)

Benincasa, Dionigi M T

2011-01-01

We investigate the relation between the two dimensional Causal Set action, S, and the Lorentzian Gauss-Bonnet theorem (LGBT). We give compelling reasons why the answer to the title's question is no. In support of this point of view we calculate the causal set inspired action of causal intervals in some two dimensional spacetimes: Minkowski, the flat cylinder and the flat trousers.

Nonsingular solutions and instabilities in Einstein-scalar-Gauss-Bonnet cosmology

Science.gov (United States)

Sberna, Laura; Pani, Paolo

2017-12-01

It is generically believed that higher-order curvature corrections to the Einstein-Hilbert action might cure the curvature singularities that plague general relativity. Here we consider Einstein-scalar-Gauss-Bonnet gravity, the only four-dimensional, ghost-free theory with quadratic curvature terms. For any choice of the coupling function and of the scalar potential, we show that the theory does not allow for bouncing solutions in the flat and open Friedmann universe. For the case of a closed universe, using a reverse-engineering method, we explicitly provide a bouncing solution which is nevertheless linearly unstable in the scalar gravitational sector. Moreover, we show that the expanding, singularity-free, early-time cosmologies allowed in the theory are unstable. These results rely only on analyticity and finiteness of cosmological variables at early times.

Black hole formation in AdS Einstein-Gauss-Bonnet gravity

Energy Technology Data Exchange (ETDEWEB)

Deppe, Nils [Cornell Center for Astrophysics and Planetary Science andDepartment of Physics, Cornell University,122 Sciences Drive, Ithaca, New York 14853 (United States); Kolly, Allison [Department of Atmospheric and Oceanic Sciences, McGill University,805 Sherbrooke Street West, Montréal, Québec H3A 0B9 (Canada); Frey, Andrew R.; Kunstatter, Gabor [Department of Physics and Winnipeg Institute for Theoretical Physics, University of Winnipeg,515 Portage Avenue, Winnipeg, Manitoba R3B 2E9 (Canada)

2016-10-17

AdS spacetime has been shown numerically to be unstable against a large class of arbitrarily small perturbations. In http://dx.doi.org/10.1103/PhysRevLett.114.071102, the authors presented a preliminary study of the effects on stability of changing the local dynamics by adding a Gauss-Bonnet term to the Einstein action. Here we provide further details as well as new results with improved numerical methods. In particular, we elucidate new structure in Choptuik scaling plots. We also provide evidence of chaotic behavior at the transition between immediate horizon formation and horizon formation after the matter pulse reflects from the AdS conformal boundary. Finally, we present data suggesting the formation of naked singularities in spacetimes with ADM mass below the algebraic bound for black hole formation.

Black hole thermodynamics and negative entropy in de Sitter and anti-de Sitter Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Cvetic, Mirjam; Nojiri, Shin'ichi; Odintsov, S.D.

2002-01-01

We investigate the charged Schwarzschild-anti-de Sitter (SAdS) BH thermodynamics in 5d Einstein-Gauss-Bonnet gravity with electromagnetic field. The Hawking-Page phase transitions between SAdS BH and pure AdS space are studied. The corresponding phase diagrams (with critical line defined by GB term coefficient and electric charge) are drawn. The possibility to account for higher derivative Maxwell terms is mentioned. In frames of proposed dS/CFT correspondence it is demonstrated that brane gravity maybe localized similarly to AdS/CFT. SdS BH thermodynamics in 5d Einstein and Einstein-Gauss-Bonnet gravity is considered. The corresponding (complicated) surface counterterms are found and used to get the conserved BH mass, free energy and entropy. The interesting feature of higher derivative gravity is the possibility for negative (or zero) SdS (or SAdS) BH entropy which depends on the parameters of higher derivative terms. We speculate that the appearance of negative entropy may indicate a new type instability where a transition between SdS (SAdS) BH with negative entropy to SAdS (SdS) BH with positive entropy would occur

Is there a relation between the 2D Causal Set action and the Lorentzian Gauss-Bonnet theorem?

Energy Technology Data Exchange (ETDEWEB)

Benincasa, Dionigi M T, E-mail: db1808@ic.ac.uk [Theoretical Physics Group, Blackett Laboratory, Imperial College, Prince Consort Rd., London SW7 2AZ (United Kingdom)

2011-07-08

We investigate the relation between the two dimensional Causal Set action, S, and the Lorentzian Gauss-Bonnet theorem (LGBT). We give compelling reasons why the answer to the title's question is no. In support of this point of view we calculate the causal set inspired action of causal intervals in some two dimensional spacetimes: Minkowski, the flat cylinder and the flat trousers.

Effect of chronic administration of Tamoxifen on fertility in male bonnet monkeys (Macaca radiata).

Science.gov (United States)

Rao, A J; Ramachandra, S G; Ramesh, V; Krishnamurthy, H N; Jayaraman, S; Gopalakrishnan, K; Juneja, H S

1998-01-01

Administration of Tamoxifen via the Alzet pump at a rate of 50 micrograms hr-1 for 90 days in the adult male bonnet monkeys Macaca radiata had no effect on the serum testosterone concentration determined at 10 AM and 10 PM as well as total sperm count determined at 15-day intervals over a period of 260 days. However, a significant reduction in sperm motility was observed beyond 90 days up until the 225th day. Breeding studies conducted from day 90 to 260 revealed that these males were infertile.

Regular black holes in Einstein-Gauss-Bonnet gravity

Science.gov (United States)

Ghosh, Sushant G.; Singh, Dharm Veer; Maharaj, Sunil D.

2018-05-01

Einstein-Gauss-Bonnet theory, a natural generalization of general relativity to a higher dimension, admits a static spherically symmetric black hole which was obtained by Boulware and Deser. This black hole is similar to its general relativity counterpart with a curvature singularity at r =0 . We present an exact 5D regular black hole metric, with parameter (k >0 ), that interpolates between the Boulware-Deser black hole (k =0 ) and the Wiltshire charged black hole (r ≫k ). Owing to the appearance of the exponential correction factor (e-k /r2), responsible for regularizing the metric, the thermodynamical quantities are modified, and it is demonstrated that the Hawking-Page phase transition is achievable. The heat capacity diverges at a critical radius r =rC, where incidentally the temperature is maximum. Thus, we have a regular black hole with Cauchy and event horizons, and evaporation leads to a thermodynamically stable double-horizon black hole remnant with vanishing temperature. The entropy does not satisfy the usual exact horizon area result of general relativity.

Cosmology of modified Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Li Baojiu; Barrow, John D.; Mota, David F.

2007-01-01

We consider the cosmology where some function f(G) of the Gauss-Bonnet term G is added to the gravitational action to account for the late-time accelerating expansion of the universe. The covariant and gauge invariant perturbation equations are derived with a method which could also be applied to general f(R,R ab R ab ,R abcd R abcd ) gravitational theories. It is pointed out that, despite their fourth-order character, such f(G) gravity models generally cannot reproduce arbitrary background cosmic evolutions; for example, the standard ΛCDM paradigm with Ω DE =0.76 cannot be realized in f(G) gravity theories unless f is a true cosmological constant because it imposes exclusionary constraints on the form of f(G). We analyze the perturbation equations and find that, as in the f(R) model, the stability of early-time perturbation growth puts some constraints on the functional form of f(G), in this case ∂ 2 f/∂G 2 <0. Furthermore, the stability of small-scale perturbations also requires that f not deviate significantly from a constant. These analyses are illustrated by numerically propagating the perturbation equations with a specific model reproducing a representative ΛCDM cosmic history. Our results show how the f(G) models are highly constrained by cosmological data

Vacuum thin shells in Einstein–Gauss–Bonnet brane-world cosmology

Science.gov (United States)

Ramirez, Marcos A.

2018-04-01

In this paper we construct new solutions of the Einstein–Gauss–Bonnet field equations in an isotropic Shiromizu–Maeda–Sasaki brane-world setting which represent a couple of Z 2-symmetric vacuum thin shells splitting from the central brane, and explore the main properties of the dynamics of the system. The matching of the separating vacuum shells with the brane-world is as smooth as possible and all matter fields are restricted to the brane. We prove the existence of these solutions, derive the criteria for their existence, analyse some fundamental aspects or their evolution and demonstrate the possibility of constructing cosmological examples that exhibit this feature at early times. We also comment on the possible implications for cosmology and the relation of this system with the thermodynamic instability of highly symmetric vacuum solutions of Lovelock theory.

La collégiale de Saint-Bonnet-le-Château (Loire

Directory of Open Access Journals (Sweden)

Bernard Ducouret

2012-04-01

Full Text Available La collégiale de Saint-Bonnet-le-Château est principalement connue pour les peintures murales du XVe siècle qui décorent sa chapelle basse, dont une partie est reproduite au musée des Monuments français, et, à un moindre degré, pour sa bibliothèque qui conserve de nombreux incunables. Son architecture, plus ignorée, n'en est pas moins digne d'intérêt. Nous ne présenterons pas ici l'ensemble de l'édifice, négligeant des éléments remarquables comme le porche sud (cf. plan, au-dessous de la sacr...

Conserved charges for black holes in Einstein-Gauss-Bonnet gravity coupled to nonlinear electrodynamics in AdS space

International Nuclear Information System (INIS)

Miskovic, Olivera; Olea, Rodrigo

2011-01-01

Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.

Thermal cracking in Lac du Bonnet granite during slow heating to 205 degrees celsius

International Nuclear Information System (INIS)

Chernis, P.J.; Robertson, P.B.

1993-09-01

Acoustic emissions (AE) were recorded as drill core samples of Lac du Bonnet granite were slowly heated to between 66 and 205 degrees celsius to evaluate the effects of temperature on the properties of rock samples. Longitudinal and shear velocities of the samples were measured, and Young's moduli, shear moduli and Poisson's ratios were calculated. No significant AE activity was detected until temperatures reached approximately 73-80 degrees celsius. Above this 'threshold' temperature, calculated rock properties decreased, and at 205 degrees celsius calculated Young's modulus, shear modulus, and Poisson's ratio were reduced by 30, 26, and 29% respectively

Iron line spectroscopy with Einstein-dilaton-Gauss-Bonnet black holes

Science.gov (United States)

Nampalliwar, Sourabh; Bambi, Cosimo; Kokkotas, Kostas D.; Konoplya, Roman A.

2018-06-01

Einstein-dilaton-Gauss-Bonnet gravity is a well-motivated alternative theory of gravity that emerges naturally from string theory. While black hole solutions have been known in this theory in numerical form for a while, an approximate analytical metric was obtained recently by some of us, which allows for faster and more detailed analysis. Here we test the accuracy of the analytical metric in the context of X-ray reflection spectroscopy. We analyze innermost stable circular orbits (ISCO) and relativistically broadened iron lines and find that both the ISCO and iron lines are determined sufficiently accurately up to the limit of the approximation. We also find that, though the ISCO increases by about 7% as dilaton coupling increases from zero to extremal values, the redshift at ISCO changes by less than 1%. Consequently, the shape of the iron line is much less sensitive to the dilaton charge than expected.

Simple inflationary models in Gauss–Bonnet brane-world cosmology

International Nuclear Information System (INIS)

Okada, Nobuchika; Okada, Satomi

2016-01-01

In light of the recent Planck 2015 results for the measurement of the cosmic microwave background (CMB) anisotropy, we study simple inflationary models in the context of the Gauss–Bonnet (GB) brane-world cosmology. The brane-world cosmological effect modifies the power spectra of scalar and tensor perturbations generated by inflation and causes a dramatic change for the inflationary predictions of the spectral index ( n s ) and the tensor-to-scalar ratio ( r ) from those obtained in the standard cosmology. In particular, the predicted r values in the inflationary models favored by the Planck 2015 results are suppressed due to the GB brane-world cosmological effect, which is in sharp contrast with inflationary scenario in the Randall–Sundrum brane-world cosmology, where the r values are enhanced. Hence, these two brane-world cosmological scenarios are distinguishable. With the dramatic change of the inflationary predictions, the inflationary scenario in the GB brane-world cosmology can be tested by more precise measurements of n s and future observations of the CMB B -mode polarization. (paper)

Nonlinear viscosity in brane-world cosmology with a Gauss–Bonnet term

Science.gov (United States)

Debnath, P. S.; Beesham, A.; Paul, B. C.

2018-06-01

Cosmological solutions are obtained with nonlinear bulk viscous cosmological fluid in the Randall–Sundrum type II (RS) brane-world model with or without Gauss–Bonnet (GB) terms. To describe such a viscous fluid, we consider the nonlinear transport equation which may be used far from equilibrium during inflation or reheating. Cosmological models are explored for both (i) power law and (ii) exponential evolution of the early universe in the presence of an imperfect fluid described by the non-linear Israel and Stewart theory (nIS). We obtain analytic solutions and the complex field equations are also analyzed numerically to study the evolution of the universe. The stability analysis of the equilibrium points of the dynamical system associated with the evolution of the nonlinear bulk viscous fluid in the RS Brane in the presence (or absence) of a GB term are also studied.

Dilaton field released under collision of dilatonic black holes with Gauss-Bonnet term

Energy Technology Data Exchange (ETDEWEB)

Gwak, Bogeun [Sejong University, Department of Physics and Astronomy, Seoul (Korea, Republic of); Ro, Daeho [POSTECH, Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk (Korea, Republic of)

2017-08-15

We investigate the upper limit of the gravitational radiation released upon the collision of two dilatonic black holes by analyzing the Gauss-Bonnet term. Dilatonic black holes have a dilaton hair coupled with this term. Using the laws of thermodynamics, the upper limit of the radiation is obtained, which reflected the effects of the dilaton hair. The amount of radiation released is greater than that emitted by a Schwarzschild black hole due to the contribution from the dilaton hair. In the collision, most of the dilaton hair can be released through radiation, where the energy radiated by the dilaton hair is maximized when the horizon of one black hole is minimized for a fixed second black hole. (orig.)

New perspective for black hole thermodynamics in Gauss-Bonnet-Born-Infeld massive gravity

International Nuclear Information System (INIS)

Hendi, Seyed Hossein; Li, Gu-Qiang; Mo, Jie-Xiong; Panahiyan, Shahram; Panah, Behzad Eslam

2016-01-01

Following an earlier study regarding Einstein-Gauss-Bonnet-massive black holes in the presence of a Born-Infeld nonlinear electromagnetic field (Hendi, arXiv:1510.00108, 2016), we study thermodynamical structure and critical behavior of these black holes through various methods in this paper. Geometrical thermodynamics is employed to give a picture regarding the phase transition of these black holes. Next, a new method is used to derive critical pressure and radius of the horizon of these black holes. In addition, Maxwell equal area law is employed to study the Van der Waals like behavior of these black holes. Moreover, the critical exponents are calculated and by using Ehrenfest equations, the type of phase transition is determined. (orig.)

New perspective for black hole thermodynamics in Gauss-Bonnet-Born-Infeld massive gravity

Energy Technology Data Exchange (ETDEWEB)

Hendi, Seyed Hossein [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM),Maragha (Iran, Islamic Republic of); Li, Gu-Qiang; Mo, Jie-Xiong [Lingnan Normal University, Institute of Theoretical Physics, Zhanjiang, Guangdong (China); Panahiyan, Shahram [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Panah, Behzad Eslam [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

2016-10-15

Following an earlier study regarding Einstein-Gauss-Bonnet-massive black holes in the presence of a Born-Infeld nonlinear electromagnetic field (Hendi, arXiv:1510.00108, 2016), we study thermodynamical structure and critical behavior of these black holes through various methods in this paper. Geometrical thermodynamics is employed to give a picture regarding the phase transition of these black holes. Next, a new method is used to derive critical pressure and radius of the horizon of these black holes. In addition, Maxwell equal area law is employed to study the Van der Waals like behavior of these black holes. Moreover, the critical exponents are calculated and by using Ehrenfest equations, the type of phase transition is determined. (orig.)

Dynamical analysis for a scalar-tensor model with Gauss-Bonnet and non-minimal couplings

Energy Technology Data Exchange (ETDEWEB)

Granda, L.N.; Jimenez, D.F. [Universidad del Valle, Departamento de Fisica, Cali (Colombia)

2017-10-15

We study the autonomous system for a scalar-tensor model of dark energy with Gauss-Bonnet and non-minimal couplings. The critical points describe important stable asymptotic scenarios including quintessence, phantom and de Sitter attractor solutions. Two functional forms for the coupling functions and the scalar potential are considered: power-law and exponential functions of the scalar field. For the exponential functions the existence of stable quintessence, phantom or de Sitter solutions, allows for an asymptotic behavior where the effective Newtonian coupling becomes constant. The phantom solutions could be realized without appealing to ghost degrees of freedom. Transient inflationary and radiation-dominated phases can also be described. (orig.)

Superior Mesenteric Artery Syndrome or Wilkie Syndrome

International Nuclear Information System (INIS)

Castano Llano, Rodrigo; Chams Anturi, Abraham; Arango Vargas, Paula

2009-01-01

We described three cases of superior mesenteric artery (SMA) syndrome, also known as Wilkie's syndrome, chronic duodenal ileus, or cast syndrome. This syndrome occurs when the third portion of the duodenum is compressed between the SMA and the aorta. The major risk factors for development of SMA syndrome are rapid weight loss and surgical correction of spinal deformities. The clinical presentation of SMA syndrome is variable and nonspecific, including nausea, vomiting, abdominal pain, and weight loss. The diagnosis is based on endoscopic, radiographic and tomographic findings of duodenal compression by the SMA. The treatment of SMA syndrome is aimed at the precipitating factor, which usually is related to weight loss. Therefore, conservative therapy with nutritional supplementation is the initial approach, and surgery is reserved for those who do not respond to nutritional therapy.

Shadows of Einstein–dilaton–Gauss–Bonnet black holes

Energy Technology Data Exchange (ETDEWEB)

Cunha, Pedro V.P., E-mail: pintodacunha@tecnico.ulisboa.pt [Departamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro (Portugal); CENTRA, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049, Lisboa (Portugal); Herdeiro, Carlos A.R., E-mail: herdeiro@ua.pt [Departamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro (Portugal); Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institute of Physics, University of Oldenburg, Oldenburg, 26111 (Germany); Kunz, Jutta, E-mail: jutta.kunz@uni-oldenburg.de [Institute of Physics, University of Oldenburg, Oldenburg, 26111 (Germany); Radu, Eugen, E-mail: eugen.radu@ua.pt [Departamento de Física da Universidade de Aveiro and Centre for Research and Development in Mathematics and Applications (CIDMA), Campus de Santiago, 3810-183 Aveiro (Portugal)

2017-05-10

We study the shadows of the fully non-linear, asymptotically flat Einstein–dilaton–Gauss–Bonnet (EdGB) black holes (BHs), for both static and rotating solutions. We find that, in all cases, these shadows are smaller than for comparable Kerr BHs, i.e. with the same total mass and angular momentum under similar observation conditions. In order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. Therefore, generically, EdGB BHs cannot be excluded by (near future) shadow observations alone. On the theoretical side, we find no clear signature of some exotic features of EdGB BHs on the corresponding shadows, such as the regions of negative (Komar, say) energy density outside the horizon. We speculate that this is due to the fact that the Komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the ADM mass, and consequently the corresponding shadows are smaller than those of comparable Kerr BHs. The analysis herein provides a clear example that it is the light ring impact parameter, rather than its “size”, that determines a BH shadow.

Energetics and optical properties of 6-dimensional rotating black hole in pure Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Abdujabbarov, Ahmadjon; Ahmedov, Bobomurat; Atamurotov, Farruh; Dadhich, Naresh; Stuchlik, Zdenek

2015-01-01

We study physical processes around a rotating black hole in pure Gauss-Bonnet (GB) gravity. In pure GB gravity, the gravitational potential has a slower fall-off as compared to the corresponding Einstein potential in the same dimension. It is therefore expected that the energetics of a pure GB black hole would be weaker, and our analysis bears out that the efficiency of energy extraction by the Penroseprocess is increased to 25.8 % and the particle acceleration is increased to 55.28 %; the optical shadow of the black hole is decreased. These are in principle distinguishing observable features of a pure GB black hole. (orig.)

Echography of the Cervix and Uterus during the Proliferative and Secretory Phases of the Menstrual Cycle in Bonnet Monkeys (Macaca radiata)

Science.gov (United States)

Chaudhari, Uddhav K; Metkari, Siddnath M; Manjaramkar, Dhyananjay D; Sachdeva, Geetanjali; Katkam, Rajendra; Bandivdekar, Atmaram H; Mahajan, Abhishek; Thakur, Meenakshi H; Kholkute, Sanjiv D

2014-01-01

We undertook the present study to investigate the echographic characteristics of the uterus and cervix of female bonnet monkeys (Macaca radiata) during the proliferative and secretory phases of the menstrual cycle. The cervix was tortuous in shape and measured 2.74 ± 0.30 cm (mean ± SD) in width by 3.10 ± 0.32 cm in length. The cervical lumen contained 2 or 3 colliculi, which projected from the cervical canal. The echogenicity of cervix varied during proliferative and secretory phases. The uterus was pyriform in shape (2.46 ± 0.28 cm × 1.45 ± 0.19 cm) and consisted of serosa, myometrium, and endometrium. The endometrium generated a triple-line pattern; the outer and central lines were hyperechogenic, whereas the inner line was hypoechogenic. The endometrium was significantly thicker during the secretory phase (0.69 ± 0.12 cm) than during the proliferative phase (0.43 ± 0.15 cm). Knowledge of the echogenic changes in the female reproductive organs of bonnet monkeys during a regular menstrual cycle may facilitate understanding of other physiologic and pathophysiologic changes. PMID:24411775

Linking the Gauss-Bonnet-Chern theorem, essential HOPF maps and membrane solitons with exotic spin and statistics

International Nuclear Information System (INIS)

Tze, Chia-Hsiung

1989-01-01

By way of the Gauss-Bonnet-Chern theorem, we present a higher dimensional extension of Polyakov's regularization of Wilson loops of point solitons. Spacetime paths of extended objects become hyper-ribbons with self-linking, twisting and writhing numbers. specifically we discuss the exotic spin and statistical phase entanglements of geometric n-membrane solitons of D-dimensional KP 1 σ-models with an added Hopf-Chern-Simons term where (n, D, K) = (0, 3, C), (2, 7, H), (6, 15, Ω). They are uniquely linked to the complex and quaternion and octonion division algebras. 22 refs

Holographic butterfly velocities in brane geometry and Einstein-Gauss-Bonnet gravity with matters

Science.gov (United States)

Huang, Wung-Hong

2018-03-01

In the first part of the paper we generalize the butterfly velocity formula to anisotropic spacetime. We apply the formula to evaluate the butterfly velocities in M-branes, D-branes, and strings backgrounds. We show that the butterfly velocities in M2-branes, M5-branes and the intersection M 2 ⊥ M 5 equal to those in fundamental strings, D4-branes and the intersection F 1 ⊥ D 4 backgrounds, respectively. These observations lead us to conjecture that the butterfly velocity is generally invariant under a double-dimensional reduction. In the second part of the paper, we study the butterfly velocity for Einstein-Gauss-Bonnet gravity with arbitrary matter fields. A general formula is obtained. We use this formula to compute the butterfly velocities in different backgrounds and discuss the associated properties.

On exponential cosmological type solutions in the model with Gauss-Bonnet term and variation of gravitational constant

International Nuclear Information System (INIS)

Ivashchuk, V.D.; Kobtsev, A.A.

2015-01-01

A D-dimensional gravitational model with Gauss.Bonnet term is considered. When an ansatz with diagonal cosmological type metrics is adopted, we find solutions with an exponential dependence of the scale factors (with respect to a @gsynchronous-like@h variable) which describe an exponential expansion of @gour@h 3-dimensional factor space and obey the observational constraints on the temporal variation of effective gravitational constant G. Among them there are two exact solutions in dimensions D = 22, 28 with constant G and also an infinite series of solutions in dimensions D ≥ 2690 with the variation of G obeying the observational data. (orig.)

On exponential cosmological type solutions in the model with Gauss-Bonnet term and variation of gravitational constant

Energy Technology Data Exchange (ETDEWEB)

Ivashchuk, V.D. [VNIIMS, Center for Gravitation and Fundamental Metrology, Moscow (Russian Federation); Peoples' Friendship University of Russia, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Kobtsev, A.A. [Peoples' Friendship University of Russia, Institute of Gravitation and Cosmology, Moscow (Russian Federation)

2015-05-15

A D-dimensional gravitational model with Gauss.Bonnet term is considered. When an ansatz with diagonal cosmological type metrics is adopted, we find solutions with an exponential dependence of the scale factors (with respect to a @gsynchronous-like@h variable) which describe an exponential expansion of @gour@h 3-dimensional factor space and obey the observational constraints on the temporal variation of effective gravitational constant G. Among them there are two exact solutions in dimensions D = 22, 28 with constant G and also an infinite series of solutions in dimensions D ≥ 2690 with the variation of G obeying the observational data. (orig.)

Hawking radiation and tunneling mechanism for a new class of black holes in Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Muneyuki, Kenji; Ohta, Nobuyoshi

2012-01-01

We study Hawking radiation in a new class of black hole solutions in Einstein-Gauss-Bonnet theory. The black hole has been argued to have vanishing mass and entropy, but finite Hawking temperature. To check if it really emits radiation, we analyze Hawking radiation using the original method of quantization of a scalar field in the black hole background and with the quantum tunneling method, and confirm that it emits radiation at the Hawking temperature. A general formula is derived for the Hawking temperature and backreaction in the tunneling approach. Physical implications of these results are discussed. (orig.)

Viscosity to entropy density ratio for non-extremal Gauss-Bonnet black holes coupled to Born-Infeld electrodynamics

Energy Technology Data Exchange (ETDEWEB)

Das, Saurav [Indian Institute of Science Education and Research Kolkata, Nadia (India); Gangopadhyay, Sunandan [Indian Institute of Science Education and Research Kolkata, Nadia (India); Inter University Centre for Astronomy and Astrophysics, Pune (India); Ghorai, Debabrata [S.N. Bose National Centre for Basic Sciences, Kolkata (India)

2017-09-15

The ratio of the shear viscosity to the entropy density (η/s) is calculated for non-extremal black holes in D dimensions with arbitrary forms of the matter Lagrangian for which the space-time metric takes a particular form. The result reduces to the standard expressions in 5 dimensions. The η/s ratio is then computed for Gauss-Bonnet black holes coupled to Born-Infeld electrodynamics in 5 dimensions. As a result we found corrections as regards the BI parameter and th result is analytically exact up to all orders in this parameter. The computations are then extended to D dimensions. (orig.)

Magnetic branes in Gauss-Bonnet gravity with nonlinear electrodynamics: correction of magnetic branes in Einstein-Maxwell gravity

Energy Technology Data Exchange (ETDEWEB)

Hendi, Seyed Hossein [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, Shahram; Panah, Behzad Eslam [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

2015-06-15

In this paper, we consider two first order corrections to both the gravity and the gauge sides of the Einstein-Maxwell gravity: Gauss-Bonnet gravity and quadratic Maxwell invariant as corrections. We obtain horizonless magnetic solutions by implying a metric representing a topological defect. We analyze the geometric properties of the solutions and investigate the effects of both corrections, and find that these solutions may be interpreted as magnetic branes. We study the singularity condition and find a nonsingular spacetime with a conical geometry. We also investigate the effects of different parameters on the deficit angle of spacetime near the origin. (orig.)

Magnetic branes in Gauss-Bonnet gravity with nonlinear electrodynamics: correction of magnetic branes in Einstein-Maxwell gravity

International Nuclear Information System (INIS)

Hendi, Seyed Hossein; Panahiyan, Shahram; Panah, Behzad Eslam

2015-01-01

In this paper, we consider two first order corrections to both the gravity and the gauge sides of the Einstein-Maxwell gravity: Gauss-Bonnet gravity and quadratic Maxwell invariant as corrections. We obtain horizonless magnetic solutions by implying a metric representing a topological defect. We analyze the geometric properties of the solutions and investigate the effects of both corrections, and find that these solutions may be interpreted as magnetic branes. We study the singularity condition and find a nonsingular spacetime with a conical geometry. We also investigate the effects of different parameters on the deficit angle of spacetime near the origin. (orig.)

Crystallization in Two Dimensions and a Discrete Gauss-Bonnet Theorem

Science.gov (United States)

De Luca, L.; Friesecke, G.

2018-02-01

We show that the emerging field of discrete differential geometry can be usefully brought to bear on crystallization problems. In particular, we give a simplified proof of the Heitmann-Radin crystallization theorem (Heitmann and Radin in J Stat Phys 22(3):281-287, 1980), which concerns a system of N identical atoms in two dimensions interacting via the idealized pair potential V(r)=+∞ if r1. This is done by endowing the bond graph of a general particle configuration with a suitable notion of discrete curvature, and appealing to a discrete Gauss-Bonnet theorem (Knill in Elem Math 67:1-7, 2012) which, as its continuous cousins, relates the sum/integral of the curvature to topological invariants. This leads to an exact geometric decomposition of the Heitmann-Radin energy into (i) a combinatorial bulk term, (ii) a combinatorial perimeter, (iii) a multiple of the Euler characteristic, and (iv) a natural topological energy contribution due to defects. An analogous exact geometric decomposition is also established for soft potentials such as the Lennard-Jones potential V(r)=r^{-6}-2r^{-12}, where two additional contributions arise, (v) elastic energy and (vi) energy due to non-bonded interactions.

Compact stars in alternative theories of gravity: Einstein-Dilaton-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Pani, Paolo; Berti, Emanuele; Cardoso, Vitor; Read, Jocelyn

2011-01-01

We develop a theoretical framework to study slowly rotating compact stars in a rather general class of alternative theories of gravity, with the ultimate goal of investigating constraints on alternative theories from electromagnetic and gravitational-wave observations of compact stars. Our Lagrangian includes as special cases scalar-tensor theories (and indirectly f(R) theories) as well as models with a scalar field coupled to quadratic curvature invariants. As a first application of the formalism, we discuss (for the first time in the literature) compact stars in Einstein-Dilaton-Gauss-Bonnet gravity. We show that compact objects with central densities typical of neutron stars cannot exist for certain values of the coupling constants of the theory. In fact, the existence and stability of compact stars sets more stringent constraints on the theory than the existence of black hole solutions. This work is a first step in a program to systematically rule out (possibly using Bayesian model selection) theories that are incompatible with astrophysical observations of compact stars.

Takotsubo cardiomyopathy precipitated by negative pressure pulmonary oedema following total thyroidectomy

Directory of Open Access Journals (Sweden)

K S Bharathi

2016-01-01

Full Text Available 'Takotsubo cardiomyopathy (TCM' or 'stress cardiomyopathy' is a reversible cardiomyopathy that is precipitated by intense emotional or physical stress. This syndrome is characterised by symptoms mimicking acute coronary syndrome with transient systolic dysfunction associated with regional wall motion abnormalities, which extend beyond a single coronary vascular bed in the absence of obstructive coronary vascular disease. The presentation of TCM and myocardial infarction is similar with sudden onset of chest pain, breathlessness as well as abnormalities in both the electrocardiogram and cardiac enzymes. It is difficult to differentiate between the two until cardiac catheterisation establishes the diagnosis. We report a case of TCM in a post-menopausal female, precipitated by negative pressure pulmonary oedema following total thyroidectomy in whom timely cardiac catheterisation established the diagnosis and influenced the management. Heightened awareness of this unique cardiomyopathy is essential to have a high index of suspicion in at-risk population for the prompt diagnosis of stress-related cardiomyopathy syndromes occurring in the perioperative period.

Characterization of Cardiac Time Intervals in Healthy Bonnet Macaques (Macaca radiata) by Using an Electronic Stethoscope

Science.gov (United States)

Kamran, Haroon; Salciccioli, Louis; Pushilin, Sergei; Kumar, Paraag; Carter, John; Kuo, John; Novotney, Carol; Lazar, Jason M

2011-01-01

Nonhuman primates are used frequently in cardiovascular research. Cardiac time intervals derived by phonocardiography have long been used to assess left ventricular function. Electronic stethoscopes are simple low-cost systems that display heart sound signals. We assessed the use of an electronic stethoscope to measure cardiac time intervals in 48 healthy bonnet macaques (age, 8 ± 5 y) based on recorded heart sounds. Technically adequate recordings were obtained from all animals and required 1.5 ± 1.3 min. The following cardiac time intervals were determined by simultaneously recording acoustic and single-lead electrocardiographic data: electromechanical activation time (QS1), electromechanical systole (QS2), the time interval between the first and second heart sounds (S1S2), and the time interval between the second and first sounds (S2S1). QS2 was correlated with heart rate, mean arterial pressure, diastolic blood pressure, and left ventricular ejection time determined by using echocardiography. S1S2 correlated with heart rate, mean arterial pressure, diastolic blood pressure, left ventricular ejection time, and age. S2S1 correlated with heart rate, mean arterial pressure, diastolic blood pressure, systolic blood pressure, and left ventricular ejection time. QS1 did not correlate with any anthropometric or echocardiographic parameter. The relation S1S2/S2S1 correlated with systolic blood pressure. On multivariate analyses, heart rate was the only independent predictor of QS2, S1S2, and S2S1. In conclusion, determination of cardiac time intervals is feasible and reproducible by using an electrical stethoscope in nonhuman primates. Heart rate is a major determinant of QS2, S1S2, and S2S1 but not QS1; regression equations for reference values for cardiac time intervals in bonnet macaques are provided. PMID:21439218

Interactions among motility, fertilizing ability, and testosterone binding on spermatozoa of bonnet monkey (Macaca radiata).

Science.gov (United States)

Warikoo, P K; Majumdar, S S; Allag, I S; Das, R P; Roy, S

1986-01-01

Fresh ejaculates of bonnet monkeys were separated into fractions rich with highly motile and sluggishly motile spermatozoa. The motility, ability to fertilize zona-free hamster eggs, and distribution of testosterone-binding sites on spermatozoa were assessed to determine the relation between these sperm functions. Two parameters of objective assessment of motility--velocity and degree of flagellar bending--were significantly correlated with the ability to form pronuclei in zona-free hamster eggs. Only spermatozoa with good motility could form pronuclei, which might be important for assessment of the fertilizing ability. The motility was directly related to the distribution of testosterone-binding sites; the fraction having mostly motile spermatozoa was distributed over the sperm surface. The technique is simple and may be used to evaluate semen of nonhuman primates.

Black holes in the dilatonic Einstein-Gauss-Bonnet theory in various dimensions. 1. Asymptotically flat black holes

International Nuclear Information System (INIS)

Guo, Zong-Kuan; Ohta, Nobuyoshi; Torii, Takashi

2008-01-01

We study spherically symmetric, asymptotically flat black hole solutions in the low-energy effective heterotic string theory, which is the Einstein gravity with Gauss-Bonnet term and the dilaton, in various dimensions. We derive the field equations for suitable ansatz for general D dimensions and construct black hole solutions of various masses numerically in D=4,5,6 and 10 dimensional spacetime with (D-2)-dimensional hypersurface with positive constant curvature. A detailed comparison with the non-dilatonic solutions is made. We also examine the thermodynamic properties of the solutions. It is found that the dilaton has significant effects on the black hole solutions, and we discuss physical consequences. (author)

Acute compartment syndrome caused by uncontrolled hypothyroidism.

Science.gov (United States)

Modi, Anar; Amin, Hari; Salzman, Matthew; Morgan, Farah

2017-06-01

Acute compartment syndrome is increased tissue pressure exceeding perfusion pressure in a closed compartment resulting in nerve and muscle ischemia. Common precipitating causes are crush injuries, burns, substance abuse, osseous or vascular limb trauma. This is a case of 42year old female with history of hypothyroidism who presented to emergency room with acute onset of severe pain and swelling in right lower extremity. Physical examination was concerning for acute compartment syndrome of right leg which was confirmed by demonstration of elevated compartmental pressures. No precipitating causes were readily identified. Further laboratory testing revealed uncontrolled hypothyroidism. Management included emergent fasciotomy and initiating thyroid hormone replacement. This case represents a rare association between acute compartment syndrome and uncontrolled hypothyroidism. We also discuss the pathogenesis of compartment syndrome in hypothyroid patients and emphasize the importance of evaluating for less common causes, particularly in setting of non-traumatic compartment syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

Thermally induced pressure locking of gate valves: A survey of valve bonnet pressurization rates

International Nuclear Information System (INIS)

Ezekoye, L.I.; Moore, W.E.

1996-01-01

Closed, water filled gate valves run the risk of becoming pressurized due to heat input from the environment or from adjacent connected piping. Thermal pressurization of gate valve bonnets may lead to the valves failing to open on demand and can even induce structural failure of valves. This paper presents an analytical prediction of the pressurization rate of a closed pressure vessel subject to uniform heating which may be considered as an upper bound to the pressurization rate that may occur in the field. Then actual valve experiences described in the literature are reviewed to determine the expected pressurization rate in existing hardware designs. A statistical approach is applied to reconcile the differing pressurization rates reported in the literature and determine a rate that can be applied in valve evaluations. The limitations of the reconciled rate are discussed

Quasinormal modes of Gauss-Bonnet black holes at large D

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,No. 5 Yiheyuan Rd, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,No. 5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University,No. 5 Yiheyuan Rd, Beijing 100871 (China); Fan, Zhong-Ying [Center for High Energy Physics, Peking University,No. 5 Yiheyuan Rd, Beijing 100871 (China); Li, Pengcheng; Ye, Weicheng [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,No. 5 Yiheyuan Rd, Beijing 100871 (China)

2016-01-15

Einstein’s General Relativity theory simplifies dramatically in the limit that the spacetime dimension D is very large. This could still be true in the gravity theory with higher derivative terms. In this paper, as the first step to study the gravity with a Gauss-Bonnet(GB) term, we compute the quasi-normal modes of the spherically symmetric GB black hole in the large D limit. When the GB parameter is small, we find that the non-decoupling modes are the same as the Schwarzschild case and the decoupled modes are slightly modified by the GB term. However, when the GB parameter is large, we find some novel features. We notice that there are another set of non-decoupling modes due to the appearance of a new plateau in the effective radial potential. Moreover, the effective radial potential for the decoupled vector-type and scalar-type modes becomes more complicated. Nevertheless we manage to compute the frequencies of the these decoupled modes analytically. When the GB parameter is neither very large nor very small, though analytic computation is not possible, the problem is much simplified in the large D expansion and could be numerically treated. We study numerically the vector-type quasinormal modes in this case.

Incompressible Navier-Stokes equation from Einstein-Maxwell and Gauss-Bonnet-Maxwell theories

International Nuclear Information System (INIS)

Niu Chao; Tian Yu; Wu Xiaoning; Ling Yi

2012-01-01

The dual fluid description for a general cutoff surface at radius r=r c outside the horizon in the charged AdS black brane bulk space-time is investigated, first in the Einstein-Maxwell theory. Under the non-relativistic long-wavelength expansion with parameter ε, the coupled Einstein-Maxwell equations are solved up to O(ε 2 ). The incompressible Navier-Stokes equation with external force density is obtained as the constraint equation at the cutoff surface. For non-extremal black brane, the viscosity of the dual fluid is determined by the regularity of the metric fluctuation at the horizon, whose ratio to entropy density η/s is independent of both the cutoff r c and the black brane charge. Then, we extend our discussion to the Gauss-Bonnet-Maxwell case, where the incompressible Navier-Stokes equation with external force density is also obtained at a general cutoff surface. In this case, it turns out that the ratio η/s is independent of the cutoff r c but dependent on the charge density of the black brane.

Gauss-Bonnet models with cosmological constant and non zero spatial curvature in D = 4

Energy Technology Data Exchange (ETDEWEB)

Armaleo, Juan Manuel [UBA, Departamento de Fisica, Buenos Aires (Argentina); Osorio Morales, Juliana; Santillan, Osvaldo P. [UBA CONICET, Departamento de Matematicas Luis Santalo (IMAS), Buenos Aires (Argentina)

2018-02-15

In the present paper the possibility of eternal universes in Gauss-Bonnet theories of gravity in four dimensions is analysed. It is shown that, for zero spatial curvature and zero cosmological constant, if the coupling is such that 0 < f{sup '}(φ) ≤ c exp((√(8))/(√(10))φ), then there are solutions that are eternal. Similar conclusions are found when a cosmological constant turned on. These conclusions are not generalized for the case when the spatial curvature is present, but we are able to find some general results about the possible nature of the singularities. The presented results correct some dubious arguments in Santillan (JCAP 7:008, 2017), although the same conclusions are reached. On the other hand, these past results are considerably generalized to a wide class of situations which were not considered in Santillan (JCAP 7:008, 2017). (orig.)

Lemierre's syndrome.

LENUS (Irish Health Repository)

O'Dwyer, D N

2012-02-01

Lemierre\\'s syndrome is a rare disease that results in an oropharyngeal infection, which precipitates an internal jugular vein thrombosis and metastatic infection. Fusobacterium necrophorum is an anaerobic Gram-negative bacillus and has been identified as the causative agent. We describe the case of a young girl whose presentation and diagnosis were confounded by a history of valvular heart disease. Infection of heart valves can produce many of the signs and symptoms associated with Lemierre\\'s syndrome. We describe the diagnosis, investigation and optimal management of this rare disorder.

Motor Tics, Tourette Syndrome, and Learning Disabilities.

Science.gov (United States)

Lerer, Robert J.

1987-01-01

Complex motor tics associated with vocal tics indicate a high likelihood of Tourette syndrome; children with this syndrome may also have learning disabilities and attentional disorders. Individuals may be treated with stimulant drugs which may precipitate or exacerbate tics. Pharmacotherapy is available for management of tics and attentional…

Bilateral uveitis and Usher syndrome: a case report.

Science.gov (United States)

Benson, Matthew D; MacDonald, Ian M

2015-03-15

Usher syndrome is a genetically heterogeneous condition and represents the most common cause of inherited combined vision and hearing loss. Deficits manifest as sensorineural hearing loss that typically develops at a young age and retinitis pigmentosa that can lead to peripheral vision loss and night blindness. As a result, this syndrome can have a significant impact on a patient's quality of life. Previous studies have described an association between Usher syndrome and Fuchs' heterochromic iridocyclitis, a form of non-granulomatous uveitis that generally presents in a unilateral manner. We present a rare finding of bilateral uveitis and, to the best of our knowledge, the first report of granulomatous uveitis as a feature in a patient with Usher syndrome. A 45-year-old Caucasian woman with a known history of retinitis pigmentosa presented to our clinic with suspected Usher syndrome, given her report of long-standing hearing loss. Aside from a mild loss in visual acuity, our patient was otherwise asymptomatic. Visual field testing, audiology and electroretinography findings supported the diagnosis of Usher syndrome. With slit lamp examination she was found to have bilateral keratic precipitates, with large, greasy-white, mutton-fat keratic precipitates on the endothelial surface of her left eye. A thorough work-up that included blood tests and imaging was negative for an alternative cause of her uveitis. We present a rare finding of bilateral uveitis and what we believe to be the first reported instance of mutton-fat keratic precipitates and granulomatous uveitis as a feature in a patient with Usher syndrome. By identifying atypical presentations of the disease, we hope to contribute to the range of ophthalmic conditions that may be seen in association with Usher syndrome.

New Gauss-Bonnet Black Holes with Curvature-Induced Scalarization in Extended Scalar-Tensor Theories.

Science.gov (United States)

Doneva, Daniela D; Yazadjiev, Stoytcho S

2018-03-30

In the present Letter, we consider a class of extended scalar-tensor-Gauss-Bonnet (ESTGB) theories for which the scalar degree of freedom is excited only in the extreme curvature regime. We show that in the mentioned class of ESTGB theories there exist new black-hole solutions that are formed by spontaneous scalarization of the Schwarzschild black holes in the extreme curvature regime. In this regime, below certain mass, the Schwarzschild solution becomes unstable and a new branch of solutions with a nontrivial scalar field bifurcates from the Schwarzschild one. As a matter of fact, more than one branch with a nontrivial scalar field can bifurcate at different masses, but only the first one is supposed to be stable. This effect is quite similar to the spontaneous scalarization of neutron stars. In contrast to the standard spontaneous scalarization of neutron stars, which is induced by the presence of matter, in our case, the scalarization is induced by the curvature of the spacetime.

Gravity localization in non-minimally coupled scalar thick braneworlds with a Gauss-Bonnet term

International Nuclear Information System (INIS)

Malagon-Morejon, D; Quiros, I; Herrera-Aguilar, A

2011-01-01

We consider a warped five-dimensional thick braneworld with a four-dimensional Poincare invariant space-time in the framework of scalar matter non-minimally coupled to gravity plus a Gauss-Bonnet term in the bulk. Scalar field and higher curvature corrections to the background equations as well as the perturbed equations are shown. A relationship between 4-dimensional and 5-dimensional Planck masses is studied in general terms. By imposing finiteness of the 4-dimensional Planck mass and regularity of the geometry, the localization properties of the tensor modes of the first order perturbed geometry are analized for an important class of solutions motivated by models with scalar fields which are minimally coupled to gravity. In order to study the gravity localization properties for this model, the normalizability condition for the lowest level of the tensor fluctuations is analized. We see that for the class of solutions examined, gravity in 4 dimensions is recovered if the curvature invariants are regular and Planck masses are finite.

Generalized spheroidal spacetimes in 5-D Einstein-Maxwell-Gauss-Bonnet gravity

Energy Technology Data Exchange (ETDEWEB)

Hansraj, Sudan [University of KwaZulu Natal, Astrophysics and Cosmology Research Unit, Durban (South Africa)

2017-08-15

The field equations for static EGBM gravity are obtained and transformed to an equivalent form through a coordinate redefinition. A form for one of the metric potentials that generalizes the spheroidal ansatz of Vaidya-Tikekar superdense stars and additionally prescribing the electric field intensity yields viable solutions. Some special cases of the general solution are considered and analogous classes in the Einstein framework are studied. In particular the Finch-Skea ansatz is examined in detail and found to satisfy the elementary physical requirements. These include positivity of pressure and density, the existence of a pressure free hypersurface marking the boundary, continuity with the exterior metric, a subluminal sound speed as well as the energy conditions. Moreover, the solution possesses no coordinate singularities. It is found that the impact of the Gauss-Bonnet term is to correct undesirable features in the pressure profile and sound speed index when compared to the equivalent Einstein gravity model. Furthermore graphical analyses suggest that higher densities are achievable for the same radial values when compared to the 5-dimensional Einstein case. The case of a constant gravitational potential, isothermal distribution as well as an incompressible fluid are studied. All exact solutions derived exhibit an equation of state explicitly. (orig.)

Gauss-Bonnet coupling constant as a free thermodynamical variable and the associated criticality

International Nuclear Information System (INIS)

Xu, Wei; Xu, Hao; Zhao, Liu

2014-01-01

The thermodynamic phase space of Gauss-Bonnet (GB) AdS black holes is extended, taking the inverse of the GB coupling constant as a new thermodynamic pressure P GB . We studied the critical behavior associated with P GB in the extended thermodynamic phase space at fixed cosmological constant and electric charge. The result shows that when the black holes are neutral, the associated critical points can only exist in five dimensional GB-AdS black holes with spherical topology, and the corresponding critical exponents are identical to those for the Van der Waals system. For charged GB-AdS black holes, it is shown that there can be only one critical point in five dimensions (for black holes with either spherical or hyperbolic topologies), which also requires the electric charge to be bounded within some appropriate range; while in d < 5 dimensions, there can be up to two different critical points at the same electric charge, and the phase transition can occur only at temperatures which are not in between the two critical values. (orig.)

Nevoid basal cell carcinoma syndrome (Gorlin-Goltz syndrome). Case report.

Science.gov (United States)

Fini, G; Belli, E; Mici, E; Virciglio, P; Moricca, L M; D'Itri, L; Leonardi, A; Malavenda, M S; Krizzuk, D; Merola, R; Maturo, A; Pasta, V

2013-01-01

Gorlin-Goltz syndrome or nevoid basal cell carcinoma syndrome (NBCCS) comprises multiple basal cell carcinomas, keratocysts of the jaw, palmar/plantar pits, spine and rib anomalies, calcifications of the falx cerebri etc. The diagnosis is made according to clinical criteria (Kimonis Criteria) and genetic ones. We studied one family where father and then his sun resulted affected by each syndrome. Gorlin-Goltz syndrome is a rare disease diagnosed according to clinical criteria sometimes difficult to integrate. The family case we presented shows how you can get diagnosis even in older age and after numerous surgeries. Patients should be given special attention and therefore should be monitorized and need multidisciplinary treatments continued in time, even a trivial change of signs and symptoms may be an important indicator of a precipitating event which puts the patient's life under threat.

Perturbed black holes in Einstein-dilaton-Gauss-Bonnet gravity: stability, ringdown, and gravitational-wave emission

CERN Document Server

Blázquez-Salcedo, Jose Luis

2016-01-01

Gravitational waves emitted by distorted black holes---such as those arising from the coalescence of two neutron stars or black holes---carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory, and (i) find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations; (ii) discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally (iii) show that...

The cannabis withdrawal syndrome: current insights

Directory of Open Access Journals (Sweden)

Bonnet U

2017-04-01

Full Text Available Udo Bonnet,1,2 Ulrich W Preuss3,4 1Department of Psychiatry, Psychotherapy and Psychosomatic Medicine, Evangelisches Krankenhaus Castrop-Rauxel, Academic Teaching Hospital of the University of Duisburg-Essen, Castrop-Rauxel, 2Department of Psychiatry and Psychotherapy, Faculty of Medicine, LVR-Hospital Essen, University of Duisburg-Essen, Essen, 3Vitos-Klinik Psychiatrie und Psychotherapie Herborn, Herborn, 4Martin Luther University Halle-Wittenberg, Halle (Saale, Germany Abstract: The cannabis withdrawal syndrome (CWS is a criterion of cannabis use disorders (CUDs (Diagnostic and Statistical Manual of Mental Disorders – Fifth Edition and cannabis dependence (International Classification of Diseases [ICD]-10. Several lines of evidence from animal and human studies indicate that cessation from long-term and regular cannabis use precipitates a specific withdrawal syndrome with mainly mood and behavioral symptoms of light to moderate intensity, which can usually be treated in an outpatient setting. Regular cannabis intake is related to a desensitization and downregulation of human brain cannabinoid 1 (CB1 receptors. This starts to reverse within the first 2 days of abstinence and the receptors return to normal functioning within 4 weeks of abstinence, which could constitute a neurobiological time frame for the duration of CWS, not taking into account cellular and synaptic long-term neuroplasticity elicited by long-term cannabis use before cessation, for example, being possibly responsible for cannabis craving. The CWS severity is dependent on the amount of cannabis used pre-cessation, gender, and heritable and several environmental factors. Therefore, naturalistic severity of CWS highly varies. Women reported a stronger CWS than men including physical symptoms, such as nausea and stomach pain. Comorbidity with mental or somatic disorders, severe CUD, and low social functioning may require an inpatient treatment (preferably qualified detox and

Inhalational Steroids and Iatrogenic Cushing's Syndrome.

Science.gov (United States)

A V, Raveendran

2014-01-01

Bronchial asthma (BA) and Allergic rhinitis (AR) are common clinical problems encountered in day to day practice, where inhalational corticosteroids (ICS) or intranasal steroids (INS) are the mainstay of treatment. Iatrogenic Cushing syndrome (CS) is a well known complication of systemic steroid administration. ICS /INS were earlier thought to be safe, but now more and more number of case reports of Iatrogenic Cushing syndrome have been reported, especially in those who are taking cytochrome P450 (CYP 450) inhibitors. Comparing to the classical clinical features of spontaneous Cushing syndrome, iatrogenic Cushing syndrome is more commonly associated with osteoporosis, increase in intra-ocular pressure, benign intracranial hypertension, aseptic necrosis of femoral head and pancreatitis, where as hypertension, hirsuitisum and menstrual irregularities are less common. Endocrine work up shows low serum cortisol level with evidence of HPA (hypothalamo-pituitary-adrenal) axis suppression. In all patients with features of Cushing syndrome with evidence of adrenal suppression always suspect iatrogenic CS. Since concomitant administration of cytochrome P450 inhibitors in patients on ICS/INS can precipitate iatrogenic CS, avoidance of CYP450 inhibitors, its dose reduction or substitution of ICS are the available options. Along with those, measures to prevent the precipitation of adrenal crisis has to be taken. An update on ICS-/INS- associated iatrogenic CS and its management is presented here.

Stable exponential cosmological solutions with zero variation of G in the Einstein-Gauss-Bonnet model with a Λ-term

Energy Technology Data Exchange (ETDEWEB)

Ernazarov, K.K. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Ivashchuk, V.D. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Center for Gravitation and Fundamental Metrology, VNIIMS, Moscow (Russian Federation)

2017-02-15

A D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Λ is considered. By assuming diagonal cosmological metrics, we find, for a certain fine-tuned Λ, a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters H > 0 and h < 0, corresponding to factor spaces of dimensions m > 3 and l > 1, respectively, with (m,l) ≠ (6,6), (7,4), (9,3) and D = 1+m+l. Any of these solutions describes an exponential expansion of three-dimensional subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics. (orig.)

Anisotropic, time-dependent solutions in maximally Gauss-Bonnet extended gravity

International Nuclear Information System (INIS)

Kitaura, Takayuki; Wheeler, J.T.

1991-01-01

In an arbitrary number of dimensions, we find the full exact anisotropic, time-dependent, diagonal-metric solutions to maximally Gauss-Bonnet extended gravity theory. This class of theories for which the lagrangian is an arbitrary linear combination of dimensionally extnded Euler forms, is the most general gravitational theory in which the field equations contain no more than second derivatives of the metric. We show that the space-time exponentially approaches an asymptotic state of constant, anisotropic curvature and prove three theorems concerning two generic types of singularities. The first theorem gives conditions for the existence of Kasner-like curvature singularities. For these the metric diverges as tsup(p i ) where Σp i = 2 k max -1 and k max is the highest power of the curvature in the lagrangian. Other critical point singularities can arise from the polynomial nature of the theory. The remaining theorems demonstrate that the generic solution is extendible at all of these other critical points and that the generic critical points occur at moments of extremal volume density of space-time. We give an explicit coordinate transformation which produces a smooth extension through the critical point. The space-time may therefore alternately expand and contract for many cycles before expanding forever or contracting to a singularity. Many particular cases are treated in detail including several power series solutions, the generalized Kasner solution to general relativity with or without cosmological constant, the perturbative solution for quadratic string gravity, and five-dimensional extended gravity. (orig.)

Neuropsychiatry of complex visual hallucinations.

Science.gov (United States)

Mocellin, Ramon; Walterfang, Mark; Velakoulis, Dennis

2006-09-01

To describe the phenomenology and pathophysiology of complex visual hallucinations (CVH) in various organic states, in particular Charles Bonnet syndrome and peduncular hallucinosis. Three cases of CVH in the setting of pontine infarction, thalamic infarction and temporoparietal epileptiform activity are presented and the available psychiatric, neurological and biological literature on the structures of the central nervous system involved in producing hallucinatory states is reviewed. Complex visual hallucinations can arise from a variety of processes involving the retinogeniculocalcarine tract, or ascending brainstem modulatory structures. The cortical activity responsible for hallucinations results from altered or reduced input into these regions, or a loss of ascending inhibition of their afferent pathways. A significant degree of overlaps exists between the concepts of Charles Bonnet syndrome and peduncular hallucinosis. The fluidity of these eponymous syndromes reduces their validity and meaning, and may result in an inappropriate attribution of the underlying pathology. An understanding of how differing pathologies may produce CVH allows for the appropriate tailoring of treatment, depending on the site and nature of the lesion and content of perceptual disturbance.

On stability of exponential cosmological solutions with non-static volume factor in the Einstein-Gauss-Bonnet model

Energy Technology Data Exchange (ETDEWEB)

Ivashchuk, V.D. [VNIIMS, Center for Gravitation and Fundamental Metrology, Moscow (Russian Federation); Peoples' Friendship University of Russia (RUDN University), Institute of Gravitation and Cosmology, Moscow (Russian Federation)

2016-08-15

A (n + 1)-dimensional gravitational model with Gauss-Bonnet term and a cosmological constant term is considered. When ansatz with diagonal cosmological metrics is adopted, the solutions with an exponential dependence of the scale factors, a{sub i} ∝ exp(v{sup i}t), i = 1,.., n, are analyzed for n > 3. We study the stability of the solutions with non-static volume factor, i.e. K(v) = sum {sub k=1}{sup n} v{sup k} ≠ 0. We prove that under a certain restriction R imposed solutions with K(v) > 0 are stable, while solutions with K(v) < 0 are unstable. Certain examples of stable solutions are presented. We show that the solutions with v{sup 1} = v{sup 2} = v{sup 3} = H > 0 and zero variation of the effective gravitational constant are stable if the restriction R is obeyed. (orig.)

Three types of superpotentials for perturbations in the Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Petrov, A N

2009-01-01

Superpotentials (antisymmetric tensor densities) in the Einstein-Gauss-Bonnet (EGB) gravity for arbitrary types of perturbations on arbitrary curved backgrounds are constructed. As a basis, the generalized conservation laws in the framework of an arbitrary D-dimensional metric theory, where conserved currents are expressed through divergences of superpotentials, are used. Such a derivation is exact (perturbations are not infinitesimal) and is approached when a solution (dynamical) is considered as a perturbed system with respect to another solution (background). Three known prescriptions are elaborated: they are the canonical Noether theorem, the Belinfante symmetrization rule and the field-theoretical derivation. All three approaches are presented in a unique way convenient for comparisons and development. Exact expressions for the 01-component of the three types of the superpotentials are derived in the case when an arbitrary static Schwarzschild-like solution in the EGB gravity is considered as a perturbed system with respect to a background of the same type. These formulae are used for calculating the mass of the Schwarzschild-anti-de Sitter black hole in the EGB gravity. As a background, both the anti-de Sitter spacetime in arbitrary dimensions and a 'mass gap' vacuum, which has no maximal set of symmetries, in five dimensions are considered. Problems and perspectives for future development, including the Lovelock gravity, are discussed.

A síndrome de Charles Bonnet e o problema dos transtornos de percepção visual nos idosos

Directory of Open Access Journals (Sweden)

German E. Berrios

2011-09-01

Full Text Available A literatura, clássica ou recente, sobre os transtornos de percepção nos idosos é revisada. A utilidade do conceito de Síndrome de Charles Bonnet, um epônimo originalmente proposto para descrever as alucinações visuais nos idosos na ausência de prejuízos cognitivos e de oftalmopatia periférica é contestada, principalmente devido à síndrome ter sido progressivamente ampliada. Descrevemos três casos representativos de pacientes idosos que desenvolveram diferentes tipos de transtornos de percepção visual. Propomos a condução de estudos sistemáticos da frequência de tais transtornos nos idosos e de quais outras patologias, particularmente cognitivas e visuais que possam estar associadas a eles.

Traumatic brain injury is unlikely precipitating Leigh syndrome due to the GJB2 mutation c.35delG

Directory of Open Access Journals (Sweden)

Josef Finsterer

2017-06-01

Full Text Available With interest we read the article by Ashrafi et al. about a 14-year-old female who is regarded to have developed Leigh syndrome (LS after traumatic brain injury (TBI. We have the following comments and concerns:We do not agree with the notion that traumatic brain injury was the precipitating factor for LS. The patient had a history of hypoacusis, which is a typical clinical manifestation of a mitochondrial disorder (MID. Hypoacusis obviously had developed long before the TBI. Additionally, the patient was diagnosed with neuropathy of the peripheral nerves two months after TBI. It is rather unlikely that neuropathy was triggered by TBI and more likely it was already present before the trauma. Thus, the initial manifestations of LS in the presented patient were most likely hypoacusis followed by neuropathy and TBI only might have triggered the seizure but not the MID. Why was the patient put on phenytoin, which is well-known to be mitochondrion-toxic? Phenytoin may worsen epilepsy and MID in general and it is conceivable that in fact phenytoin was responsible for worsening of the phenotype and not the TBI. In a 16-year-old female with MELAS syndrome due to the mutation m.3243A>G, phenytoin caused intestinal pseudo-obstruction one month after intravenous phenytoin for status epilepticus. In a patient with Kearns-Sayre syndrome phenytoin decreased cerebrospinal fluid (CSF folate levels. In rat hepatocytes, phenytoin increased reactive oxygen species (ROS formation, decreased intracellular reduced glutathione, increased intracellular oxidised glutathione, and enhanced lipid peroxidation and mitochondrial damage. In a hepatic microsomal system, phenytoin decreased state-3 respiration, ATP synthesis, and the mitochondrial membrane potential. In this model, phenytoin increased state-4 respiration, impaired Ca++-uptake and release, and inhibited Ca++-induced swelling. It would be interesting to know how the GJB2 mutation was detected. Was whole exome or

Myxedema coma in a patient with Down's syndrome.

Science.gov (United States)

Bansal, Darpan; Nanda, Ashish; Gupta, Ekta; Croker, Mary; Williams, Misty L; Bacchus, Amy; Simmons, Debra; Erbland, Marcia

2006-11-01

hyroid dysfunction is common in Down's syndrome, most common being hypothyroidism. Longstanding, untreated hypothyroidism can lead to myxedema coma. Here we report a patient with Down's syndrome who presented with myxedema coma. The three essential elements for the diagnosis of myxedema coma include altered mental status, defective thermoregulation and a precipitating event or illness; all of these were present in our patient. Also, very high TSH, low T3 and T4, and the rapid response to the treatment with levothyroxine confirmed the diagnosis. Patients with Down's syndrome should have regular screening for thyroid dysfunction.

Paciente con síndrome de Charles Bonnet: propuesta de cuidados

Directory of Open Access Journals (Sweden)

M.ª Lourdes Jiménez Navascués

Full Text Available Objetivo: El objetivo de este trabajo es mejorar la comprensión de las experiencias de los pacientes con síndrome de Charles Bonnet (SBC y proponer un plan de cuidados de enfermería. Profundizar sobre la propia experiencia del enfermo puede aportar conocimientos, que orienten a las enfermeras, en la detección de estos pacientes y a establecer un cuidado integral de la persona con SCB, aplicando la metodología de la disciplina, con el objetivo de mejorar la calidad de vida de los pacientes. Método: Revisión y análisis del caso de una mujer de 87 años de edad, con diagnóstico de degeneración macular asociada a la edad (DMAE, que causó baja visión en ambos ojos y se diagnostica con SCB en el servicio de oftalmología. Se realiza un abordaje cualitativo y se elige el relato biográfico, válido para conocer el significado de estar enfermo e incorporar la perspectiva del paciente en las intervenciones de salud. Resultados: La paciente fue diagnosticada de SCB secundario a la DMAE. Ella describe las siguientes unidades temáticas: las alucinaciones, las emociones asociadas, el diagnóstico y atención de la salud y, por último, el afrontamiento. Conclusiones: Se hace hincapié en la importancia de la ayuda profesional desde el comienzo de las alucinaciones, para evitar temores infundados y el adecuado seguimiento de su evolución.

Dating fractures and fracture movement in the Lac du Bonnet Batholith

International Nuclear Information System (INIS)

Gascoyne, M.; Brown, A.; Ejeckam, R.B.; Everitt, R.A.

1997-04-01

This report examines and summarizes all work that has been done from 1980 to the present in determining the age of rock crystallization, fracture initiation, fracture reactivation and rates of fracture movement in the Lac du Bonnet Batholith to provide information for Atomic Energy of Canada Limited's (AECL) Canadian Nuclear Fuel Waste Management Program. Geological and petrographical indicators of relative age (e.g. cross-cutting relationships, sequences of fracture infilling minerals, P-T characteristics of primary and secondary minerals) are calibrated with radiometric age determinations on minerals and whole rock samples, using 87 Rb- 87 Sr, 40 K- 39 Ar, 40 Ar- 39 Ar and fission track methods. Most fractures and fracture zones inclined at low angles are found to be ancient features, first formed in the Early Proterozoic under conditions of deuteric alteration. Following some movement on fractures in the Late Proterozoic and Early Paleozoic, reactivation of fractures during the Pleistocene is established from uranium-series dating methods and use of stable isotopic contents of fracture infilling minerals (mainly calcite). Some indication of movement on fracture zones during the Pleistocene is given by electron spin resonance dating techniques on fault gouge. The slow rate of propagation of fractures is indicated by mineral infillings, their P-T characteristics and U-series calcite ages in a fracture in sparsely fractured rock, accessible from AECL's Underground Research Laboratory. These results collectively indicate that deep fractures observed in the batholith are ancient features and the fracturing and jointing in the upper 200 m is relatively recent (< 1 Ma) and largely a result of stress release. (author)

Hepatorenal Syndrome

Directory of Open Access Journals (Sweden)

Ebru Yilmaz

2014-06-01

Full Text Available Hepatorenal syndrome (HRS is functional renal failure that occurs with advanced liver failure. HRS is considered the most severe complication of cirrhosis. Type 1 HRS develops due to severe reduction of effective circulating volume results in hemodynamic dysfunction. Type 1 HRS is characterized by acute renal failure and rapid deterioration in the function of other organs. It can ocur spontaneously or in the setting of a precipitating event. Type 2 hepatorenal syndrome (HRS, which is characterized by slowly progressive renal failure and refractory ascites. Liver transplantation is the only definitive treatment for both type. The most suitable and ldquo;bridge treatments and rdquo; or treatment for patients ineligible for a liver transplant include terlipressin plus albumin. [J Contemp Med 2014; 4(2.000: 106-113

Bipedal locomotion of bonnet macaques after spinal cord injury.

Science.gov (United States)

Babu, Rangasamy Suresh; Anand, P; Jeraud, Mathew; Periasamy, P; Namasivayam, A

2007-10-01

Experimental studies concerning the analysis of locomotor behavior in spinal cord injury research are widely performed in rodent models. The purpose of this study was to quantitatively evaluate the degree of functional recovery in reflex components and bipedal locomotor behavior of bonnet macaques (Macaca radiata) after spinal contusive injury. Six monkeys were tested for various reflex components (grasping, righting, hopping, extension withdrawal) and were trained preoperatively to walk in bipedal fashion on the simple and complex locomotor runways (narrow beam, grid, inclined plane, treadmill) of this investigation. The overall performance of the animals'motor behavior and the functional status of limb movements during bipedal locomotion were graded by the Combined Behavioral Score (CBS) system. Using the simple Allen weight-drop technique, a contusive injury was produced by dropping a 13-g weight from a height of 30 cm to the exposed spinal cord at the T12-L1 vertebral level of the trained monkeys. All the monkeys showed significant impairments in every reflex activity and in walking behavior during the early part of the postoperative period. In subsequent periods, the animals displayed mild alterations in certain reflex responses, such as grasping, extension withdrawal, and placing reflexes, which persisted through a 1-year follow-up. The contused animals traversed locomotor runways--narrow beam, incline plane, and grid runways--with more steps and few errors, as evaluated with the CBS system. Eventually, the behavioral performance of all spinal-contused monkeys recovered to near-preoperative level by the fifth postoperative month. The findings of this study reveal the recovery time course of various reflex components and bipedal locomotor behavior of spinal-contused macaques on runways for a postoperative period of up to 1 year. Our spinal cord research in primates is advantageous in understanding the characteristics of hind limb functions only, which possibly

Acute Pulmonary Edema in an Eclamptic Pregnant Patient: A Rare Case of Takotsubo Syndrome.

Science.gov (United States)

Karamchandani, Kunal; Bortz, Brandon; Vaida, Sonia

2016-09-23

BACKGROUND Acute pulmonary edema in a pregnant patient is associated with significant morbidity and mortality. Takotsubo syndrome, or stress-induced cardiomyopathy, is a rare cause of acute pulmonary edema in a pregnant patient, especially prior to delivery of the fetus. CASE REPORT We describe a case of a pregnant patient who presented with acute pulmonary edema and eclampsia and was found to have Takotsubo syndrome. To the best of our knowledge, eclampsia as a precipitating factor for Takotsubo syndrome has not been described in literature. CONCLUSIONS Clinicians taking care of pregnant patients should be aware of the potential link between eclampsia and Takotsubo cardiomyopathy. Prompt correction of the precipitating cause along with supportive management as described is the key to a successful outcome.

Precipitation and measurements of precipitation

NARCIS (Netherlands)

Schmidt, F.H.; Bruin, H.A.R. de; Attmannspacher, W.; Harrold, T.W.; Kraijenhoff van de Leur, D.A.

1977-01-01

In Western Europe, precipitation is normal phenomenon; it is of importance to all aspects of society, particularly to agriculture, in cattle breeding and, of course, it is a subject of hydrological research. Precipitation is an essential part in the hydrological cycle. How disastrous local

The Contribution of Extreme Precipitation to the Total Precipitation in China

Institute of Scientific and Technical Information of China (English)

SUN Jian-Qi

2012-01-01

Using daily precipitation data from weather stations in China, the variations in the contribution of extreme precipitation to the total precipitation are analyzed. It is found that extreme precipitation accounts for approximately one third of the total precipitation based on the overall mean for China. Over the past half century, extreme precipitation has played a dominant role in the year-to-year variability of the total precipitation. On the decadal time scale, the extreme precipitation makes different contributions to the wetting and drying regions of China. The wetting trends of particular regions are mainly attributed to increases in extreme precipitation; in contrast, the drying trends of other regions are mainly due to decreases in non-extreme precipitation.

[Pathogenetic relationship between pterygium and dry eye syndrome (clinical and cytological study)].

Science.gov (United States)

Petraevskiĭ, A V; Trishkin, K S

2014-01-01

To study the prevalence of dry eye syndrome in patients with initial primary pterygium for determination of a possible pathogenetic role of dry eye syndrome in the development of pterygium. 30 patients with initial primary pterygium; besides conventional ophthalmic assessment, cytological examination of bulbar conjunctiva was performed in all cases. Signs of dry eye syndrome, of similar severity in both eyes, were found in 100% of patients. Dry eye can be one of the precipitating factors of primary pterygium.

A rare case of Charlin's syndrome

Directory of Open Access Journals (Sweden)

Mohit P Singh

2017-01-01

Full Text Available Charlin's syndrome is an extremely rare condition characterized by pain in the nasal and paranasal areas, which is precipitated by touching the lateral aspect of the ipsilateral nostril. We are presenting one such case of a 42-year-old man who was admitted to Dr. Chaudhary Hospital and Medical Research Centre.

Primordial spectra of slow-roll inflation at second-order with the Gauss-Bonnet correction

Science.gov (United States)

Wu, Qiang; Zhu, Tao; Wang, Anzhong

2018-05-01

The slow-roll inflation for a single scalar field that couples to the Gauss-Bonnet (GB) term represents an important higher-order curvature correction inspired by string theory. With the arrival of the era of precision cosmology, it is expected that the high-order corrections become more and more important. In this paper we study the observational predictions of the slow-roll inflation with the GB term by using the third-order uniform asymptotic approximation method. We calculate explicitly the primordial power spectra, spectral indices, running of the spectral indices for both scalar and tensor perturbations, and the ratio between tensor and scalar spectra. These expressions are all written in terms of the Hubble and GB coupling flow parameters and expanded up to the next-to-leading order in the slow-roll expansions so they represent the most accurate results obtained so far in the literature. In addition, by studying the theoretical predictions of the scalar spectral index and the tensor-to-scalar ratio with the Planck 2015 constraints in a model with power-law potential and GB coupling, we show that the second-order corrections are important in the future measurements. We expect that the understanding of the GB corrections in the primordial spectra and their constraints by forthcoming observational data will provide clues for the UV complete theory of quantum gravity, such as the string/M-theory.

Salts-based size-selective precipitation: toward mass precipitation of aqueous nanoparticles.

Science.gov (United States)

Wang, Chun-Lei; Fang, Min; Xu, Shu-Hong; Cui, Yi-Ping

2010-01-19

Purification is a necessary step before the application of nanocrystals (NCs), since the excess matter in nanoparticles solution usually causes a disadvantage to their subsequent coupling or assembling with other materials. In this work, a novel salts-based precipitation technique is originally developed for the precipitation and size-selective precipitation of aqueous NCs. Simply by addition of salts, NCs can be precipitated from the solution. After decantation of the supernatant solution, the precipitates can be dispersed in water again. By means of adjusting the addition amount of salt, size-selective precipitation of aqueous NCs can be achieved. Namely, the NCs with large size are precipitated preferentially, leaving small NCs in solution. Compared with the traditional nonsolvents-based precipitation technique, the current one is simpler and more rapid due to the avoidance of condensation and heating manipulations used in the traditional precipitation process. Moreover, the salts-based precipitation technique was generally available for the precipitation of aqueous nanoparticles, no matter if there were semiconductor NCs or metal nanoparticles. Simultaneously, the cost of the current method is also much lower than that of the traditional nonsolvents-based precipitation technique, making it applicable for mass purification of aqueous NCs.

The Global Precipitation Climatology Project (GPCP) Combined Precipitation Dataset

Science.gov (United States)

Huffman, George J.; Adler, Robert F.; Arkin, Philip; Chang, Alfred; Ferraro, Ralph; Gruber, Arnold; Janowiak, John; McNab, Alan; Rudolf, Bruno; Schneider, Udo

1997-01-01

The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.

História natural e as idéias de geração e herança no século XVIII: Buffon e Bonnet Natural history and eighteenth-century ideas regarding generation and heredity: Buffon and Bonnet

Directory of Open Access Journals (Sweden)

Luzia Aurelia Castañeda

1995-10-01

Full Text Available No percurso intelectual da história natural pode-se detectar três aspectos conceituais. O primeiro deles é dado pelo enfoque à taxonomia, na qual o naturalista tinha como objetivo nomear e classificar os seres criados por Deus. O segundo aspecto é dado pelo suporte filosófico da época. O mecanicismo, emprestando seu método de análise à história natural, buscou compreender a engrenagem dos organismos, pois o mundo 'funcionava'. O terceiro aspecto aponta para uma inadequação do método até então utilizado, pois, diante de uma matéria viva que apresentava características distintas da matéria bruta, havia a necessidade de se entender o processo e não apenas decompor os fenômenos para, então, analisá-los. É nesse ponto do percurso que as idéias de geração e herança evidenciam tal inadequação, atribuindo ao ser vivo uma história reprodutiva, na qual a formação do semelhante pelo semelhante tem um papel importante para a compreensão da engrenagem da vida. O presente artigo apresentará uma análise desses aspectos, fundamentada nas idéias de reprodução e herança de Buffon e Bonnet, representantes de escolas distintas de pensamentos: a epigênese e o preformismo, respectivamente.The intellectual course of natural history reveals three conceptual approaches. The first was the taxonomic point of view, where naturalists worked to name and classify the living beings created by God. The second approach was provided by the eighteenth century's philosophical doctrine of mechanism, which lent natural history its method of endeavoring to comprehend the workings of organisms, inasmuch as the world "ran". Calling into question the adequacy of prior message, the third approach argued that living things display characteristics quite distinct from those of non-living matter, making it necessary to understand processes rather than simply decompose phenomena to then analyze them. This inadequacy became apparent at the moment when

SCN1A-related Dravet syndrome : Vaccinations and seizure precipitants in disease course and diagnosis

NARCIS (Netherlands)

Verbeek, N.E.

2015-01-01

Febrile seizures are well known adverse events following childhood vaccinations. If a seizure following vaccination is the first of an evolving epilepsy syndrome, the vaccination might be misinterpreted as the primary cause of the epilepsy. Dravet syndrome (formerly known as severe myoclonic

Catastrophic antiphospholipid syndrome: task force report summary.

Science.gov (United States)

Cervera, R; Rodríguez-Pintó, I

2014-10-01

The Task Force on Catastrophic Antiphospholipid Syndrome (CAPS) aimed to assess the current knowledge on pathogenesis, clinical and laboratory features, diagnosis and classification, precipitating factors and treatment of CAPS. This article summarizes the main aspects of its final report. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

ToF-SIMS imaging of capsaicinoids in Scotch Bonnet peppers (Capsicum chinense).

Science.gov (United States)

Tyler, Bonnie J; Peterson, Richard E; Lee, Therese G; Draude, Felix; Pelster, Andreas; Arlinghaus, Heinrich F

2016-06-13

Peppers (Capsicum spp.) are well known for their ability to cause an intense burning sensation when eaten. This organoleptic response is triggered by capsaicin and its analogs, collectively called capsaicinoids. In addition to the global popularity of peppers as a spice, there is a growing interest in the use of capsaicinoids to treat a variety of human ailments, including arthritis, chronic pain, digestive problems, and cancer. The cellular localization of capsaicinoid biosynthesis and accumulation has previously been studied by fluorescence microscopy and electron microscopy, both of which require immunostaining. In this work, ToF-SIMS has been used to image the distribution of capsaicinoids in the interlocular septum and placenta of Capsicum chinense (Scotch Bonnet peppers). A unique cryo-ToF-SIMS instrument has been used to prepare and analyze the samples with minimal sample preparation. Samples were frozen in liquid propane, cryosectioned in vacuum, and analyzed without exposure to ambient pressure. ToF-SIMS imaging was performed at -110 °C using a Bi3 (+) primary ion beam. Molecular ions for capsaicin and four other capsaicinoids were identified in both the positive and negative ToF-SIMS spectra. The capsaicinoids were observed concentrated in pockets between the outer walls of the palisade cells and the cuticle of the septum, as well as in the intercellular spaces in both the placenta and interlocular septum. This is the first report of label-free direct imaging of capsaicinoids at the cellular level in Capsicum spp. These images were obtained without the need for labeling or elaborate sample preparation. The study demonstrates the usefulness of ToF-SIMS imaging for studying the distribution of important metabolites in plant tissues.

On the Precipitation and Precipitation Change in Alaska

Directory of Open Access Journals (Sweden)

Gerd Wendler

2017-12-01

Full Text Available Alaska observes very large differences in precipitation throughout the state; southeast Alaska experiences consistently wet conditions, while northern Arctic Alaska observes very dry conditions. The maximum mean annual precipitation of 5727 mm is observed in the southeastern panhandle at Little Port Arthur, while the minimum of 92 mm occurs on the North Slope at Kuparuk. Besides explaining these large differences due to geographic and orographic location, we discuss the changes in precipitation with time. Analyzing the 18 first-order National Weather Service stations, we found that the total average precipitation in the state increased by 17% over the last 67 years. The observed changes in precipitation are furthermore discussed as a function of the observed temperature increase of 2.1 °C, the mean temperature change of the 18 stations over the same period. This observed warming of Alaska is about three times the magnitude of the mean global warming and allows the air to hold more water vapor. Furthermore, we discuss the effect of the Pacific Decadal Oscillation (PDO, which has a strong influence on both the temperature and precipitation in Alaska.

Optimization of precipitation conditions of thorium oxalate precipitate

International Nuclear Information System (INIS)

Pazukhin, Eh.M.; Smirnova, E.A.; Krivokhatskij, A.S.; Pazukhina, Yu.L.; Kiselev, P.P.

1986-01-01

Thorium precipitation in the form of difficultly soluble oxalate has been investigated. The equation binding the concentration of metal with the nitric acid in the initial solution and quantity of a precipitator necessary for minimization of desired product losses is derived. The graphical solution of this equation for a case, when the oxalic acid with 0.78 mol/l concentration is the precipitator, is presented

Fatty emaciation: a case report of suspected fat overload syndrome in oral refeeding.

Science.gov (United States)

Macher, Arielle D; Palazuelos, Daniel; Maviglia, Saverio M

2012-07-01

Refeeding syndrome has been observed in patients receiving nutrition after a prolonged period of malnourishment and is characterized by multiple metabolic derangements. Besides hypophosphatemia and hypoglycemia, lipemia has been described in association with parenteral nutrition administration to the malnourished. The authors describe one anorexic patient who developed lipemia during oral refeeding, followed by a precipitous drop in hematocrit suggestive of fat overload syndrome.

[Treatable diseases of the nervous system with cataract formation].

Science.gov (United States)

Baumgartner, R W; Waespe, W

1993-02-01

The detection of a cataract in combination with a neurological deficit may provide the physician with important diagnostic help. But a minority of underlying diseases (angiokeratoma corporis diffusum, cerebrotendinous xanthomatosis, diabetes mellitus, galactosemia, hypocalcemia, Refsum's disease, Wilson's disease; Charles Bonnet syndrome; relapsing Perichondritis; adverse effects of medication and intoxications) can be treated causally. Therefore they are summed up and discussed in this paper.

Properties of Extreme Precipitation and Their Uncertainties in 3-year GPM Precipitation Radar Data

Science.gov (United States)

Liu, N.; Liu, C.

2017-12-01

Extreme high precipitation rates are often related to flash floods and have devastating impacts on human society and the environments. To better understand these rare events, 3-year Precipitation Features (PFs) are defined by grouping the contiguous areas with nonzero near-surface precipitation derived using Global Precipitation Measurement (GPM) Ku band Precipitation Radar (KuPR). The properties of PFs with extreme precipitation rates greater than 20, 50, 100 mm/hr, such as the geographical distribution, volumetric precipitation contribution, seasonal and diurnal variations, are examined. In addition to the large seasonal and regional variations, the rare extreme precipitation rates often have a larger contribution to the local total precipitation. Extreme precipitation rates occur more often over land than over ocean. The challenges in the retrieval of extreme precipitation might be from the attenuation correction and large uncertainties in the Z-R relationships from near-surface radar reflectivity to precipitation rates. These potential uncertainties are examined by using collocated ground based radar reflectivity and precipitation retrievals.

A study of uranium series disequilibrium in core profiles and mineral separates from the samples of Lac du Bonnet granite from the URL site, Pinawa, Manitoba, Canada

International Nuclear Information System (INIS)

Ivanovich, M.; Longworth, G.; Wilkins, M.A.; Hasler, S.E.

1987-12-01

Uranium series disequilibrium measurements of actinide activities and activity ratios have been used to study the geochemical history of Lac du Bonnet granite, from the URL site, Pinawa, Canada. Measurements on core profiles between fractured surfaces and the parent rock show that the granite underwent high temperature events several million years ago, followed by more recent low temperature events within the last million years. The main locations for the rock/water interaction and exchange of actinides are the fracture surfaces. The results of similar measurements on separated mineral phases show that the 'soft' minerals such as biotite and feldspar are more vulnerable to weathering than the 'hard' accessory minerals such as zircon. (author)

Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

International Nuclear Information System (INIS)

Hoyt, R.C.

1978-04-01

A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 μ in diameter and contained numerous small voids (less than 0.3 μm) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 μm in diameter and contained large voids (approximately 1 μm). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost

Precipitation kinetics of a continuous precipitator, with application to the precipitation of ammonium polyuranate

Energy Technology Data Exchange (ETDEWEB)

Hoyt, R.C.

1978-04-01

A mathematical model describing the kinetics of continuous precipitation was developed which accounts for crystal nucleation, crystal growth, primary coagulation, and secondary coagulation. Population density distributions, average particle sizes, dominant particle sizes, and suspension density fractions of the crystallites, primary agglomerates, and secondary agglomerates leaving the continuous precipitator can be determined. This kinetic model was applied to the continuous precipitation of ammonium polyuranate, which consists of: (1) elementary crystals, (2) clusters or primary coagulated particles, and (3) agglomerates or secondary coagulated particles. The crystallites are thin, submicron, hexagonal platelets. The clusters had an upper size limit of about 7 ..mu.. in diameter and contained numerous small voids (less than 0.3 ..mu..m) due to the packing of the crystallites. The agglomerates had an upper size limit of about 40 ..mu..m in diameter and contained large voids (approximately 1 ..mu..m). The particle size distribution and particle structure of the ammonium polyuranate precipitate can be controlled through proper regulation of the precipitation conditions. The ratio of clusters to agglomerates can be best controlled through the uranium concentration, and the cohesiveness or internal bonding strength of the particles can be controlled with the ammonium to uranium reacting feed mole ratio. These two conditions, in conjunction with the residence time, will determine the nucleation rates, growth rates, and size distributions of the particles leaving the continuous precipitator. With proper control of these physical particle characteristics, the use of pore formers, ball-milling, and powder blending can probably be eliminated from the nuclear fuel fabrication process, substantially reducing the cost.

Small dark energy and stable vacuum from Dilaton-Gauss-Bonnet coupling in TMT

Energy Technology Data Exchange (ETDEWEB)

Guendelman, Eduardo I. [Ben-Gurion University of the Negev, Department of Physics, Beer-Sheva (Israel); Nishino, Hitoshi; Rajpoot, Subhash [California State University at Long Beach, Long Beach, CA (United States)

2017-04-15

In two measures theories (TMT), in addition to the Riemannian measure of integration, being the square root of the determinant of the metric, we introduce a metric-independent density Φ in four dimensions defined in terms of scalars φ{sub a} by Φ = ε{sup μνρσ} ε{sub abcd}(∂{sub μ}φ{sub a})(∂{sub ν}φ{sub b})(∂{sub ρ}φ{sub c})(∂{sub σ}φ{sub d}). With the help of a dilaton field φ we construct theories that are globally scale invariant. In particular, by introducing couplings of the dilaton φ to the Gauss-Bonnet (GB) topological density √(-g)φ (R{sub μνρσ}{sup 2} - 4R{sub μν}{sup 2} + R{sup 2}) we obtain a theory that is scale invariant up to a total divergence. Integration of the φ{sub a} field equation leads to an integration constant that breaks the global scale symmetry. We discuss the stabilizing effects of the coupling of the dilaton to the GB-topological density on the vacua with a very small cosmological constant and the resolution of the 'TMT Vacuum-Manifold Problem' which exists in the zero cosmological-constant vacuum limit. This problem generically arises from an effective potential that is a perfect square, and it gives rise to a vacuum manifold instead of a unique vacuum solution in the presence of many different scalars, like the dilaton, the Higgs, etc. In the non-zero cosmological-constant case this problem disappears. Furthermore, the GB coupling to the dilaton eliminates flat directions in the effective potential, and it totally lifts the vacuum-manifold degeneracy. (orig.)

Reversible Cerebral Vasoconstriction Syndrome in Pediatrics: A Case Series and Review.

Science.gov (United States)

Coffino, Samantha W; Fryer, Robert H

2017-06-01

Reversible cerebral vasoconstriction syndrome is a transient vasculopathy associated with severe headaches and stroke. In most cases of reversible cerebral vasoconstriction syndrome, there is a precipitating event or trigger, such as pregnancy, serotonin agonist treatment or illicit drug use. The authors present 2 pediatric cases of reversible cerebral vasoconstriction syndrome and review the previous 11 pediatric cases in the literature. In many instances, the clinical and radiographic features are similar in both pediatric and adult cases. In the pediatric group, reported potential triggers include trauma (1/13), exercise (2/13), water to the face (3/13), hypertension (3/13), and medication or substance use (4/13). One surprising difference is that 11 out of 13 pediatric patients with reversible cerebral vasoconstriction syndrome are male while most cases in adults are female. Many of the pediatric patients with reversible cerebral vasoconstriction syndrome were treated with a calcium channel blocker and the overall outcome of pediatric reversible cerebral vasoconstriction syndrome was good, with most patients experiencing a full recovery.

Use of ultrasound imaging for the diagnosis of abnormal uterine bleeding in the bonnet macaque ( Macaca radiata).

Science.gov (United States)

Chaudhari, Uddhav K; Imran, M; Manjramkar, Dhananjay D; Metkari, Siddhanath M; Sable, Nilesh P; Gavhane, Dnyaneshwar S; Katkam, Rajendra R; Sachdeva, Geetanjali; Thakur, Meenakshi H; Kholkute, Sanjeeva D

2017-02-01

Ultrasound is a powerful, low-cost, non-invasive medical tool used by laboratory animal veterinarians for diagnostic imaging. Sonohysterography and transvaginal ultrasound are frequently used to assess uterine anomalies in women presenting with abnormal uterine bleeding (AUB). In the present study, we have evaluated the abdominal ultrasound of bonnet monkeys ( n = 8) showing spontaneous ovulatory ( n = 5) and anovulatory ( n = 3) AUB. The ovulatory ( n = 5) macaques showed cyclic AUB for 7-8 days. The anovulatory ( n = 3) macaques had irregular AUB with menstrual cycles of 40-45 days. The B-mode abdominal, colour Doppler and 3D ultrasound scans were performed during the proliferative phase of the menstrual cycle. Ultrasound examination revealed endometrial polyps in five macaques and endometrial hyperplasia in three animals. The width and length of endometrial polyps was around 0.5-1 cm (average 0.51 ± 0.23 cm × 0.96 ± 0.16 cm) with significant increase in endometrial thickness ( P uterine cavity and colour Doppler ultrasound showed increased vascularity in the endometrial polyps. Endometrial hyperplasia characteristically appeared as a thickened echogenic endometrium ( P < 0.0002). This study demonstrates the use of non-invasive ultrasound techniques in the diagnosis of AUB in macaques.

Climate change and precipitation: Detecting changes Climate change and precipitation: Detecting changes

International Nuclear Information System (INIS)

Van Boxel, John H

2001-01-01

Precipitation is one of the most, if not the most important climate parameter In most studies on climate change the emphasis is on temperature and sea level rise. Often too little attention is given to precipitation. For a large part this is due to the large spatial en temporal variability of precipitation, which makes the detection of changes difficult. This paper describes methods to detect changes in precipitation. In order to arrive at statistically significant changes one must use long time series and spatial averages containing the information from several stations. In the Netherlands the average yearly precipitation increased by 11% during the 20th century .In the temperate latitudes on the Northern Hemisphere (40-60QN) the average increase was about 7% over the 20th century and the globally averaged precipitation increased by about 3%. During the 20th century 38% of the land surface of the earth became wetter, 42% experienced little change (less than 5% change) and 20% became dryer. More important than the average precipitation is the occurrence of extremes. In the Netherlands there is a tendency to more extreme precipitations, whereas the occurrence of relatively dry months has not changed. Also in many other countries increases in heavy precipitation events are observed. All climate models predict a further increase of mean global precipitation if the carbon dioxide concentration doubles. Nevertheless some areas get dryer, others have little change and consequently there are also areas where the increase is much more than the global average. On a regional scale however there are large differences between the models. Climate models do not yet provide adequate information on changes in extreme precipitations

Precipitous Birth

Directory of Open Access Journals (Sweden)

Jennifer Yee

2017-09-01

Full Text Available Audience: This scenario was developed to educate emergency medicine residents on the management of a precipitous birth in the emergency department (ED. The case is also appropriate for teaching of medical students and advanced practice providers, as well as reviewing the principles of crisis resource management, teamwork, and communication. Introduction: Patients with precipitous birth require providers to manage two patients simultaneously with limited time and resources. Crisis resource management skills will be tested once baby is delivered, and the neonate will require assessment for potential neonatal resuscitation. Objectives: At the conclusion of the simulation session, learners will be able to manage women who have precipitous deliveries, as well as perform neonatal assessment and management. Method: This session was conducted using high-fidelity simulation, followed by a debriefing session and lecture on precipitous birth management and neonatal evaluation.

Drug Reaction, Eosinophilia and Systemic Symptoms (DRESS) syndrome secondary to allopurinol with early lymphadenopathy and symptom relapse.

Science.gov (United States)

Turney, Rhiannon; Skittrall, Jordan Peter; Donovan, Joseph; Agranoff, Daniel

2015-10-05

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare condition with a mortality rate of up to 10%. Herein, we describe a case of DRESS syndrome secondary to allopurinol and which may have been precipitated by amoxicillin, the diagnostic challenge it represented and the successful treatment of the condition with corticosteroids. 2015 BMJ Publishing Group Ltd.

Precipitation isoscapes for New Zealand: enhanced temporal detail using precipitation-weighted daily climatology.

Science.gov (United States)

Baisden, W Troy; Keller, Elizabeth D; Van Hale, Robert; Frew, Russell D; Wassenaar, Leonard I

2016-01-01

Predictive understanding of precipitation δ(2)H and δ(18)O in New Zealand faces unique challenges, including high spatial variability in precipitation amounts, alternation between subtropical and sub-Antarctic precipitation sources, and a compressed latitudinal range of 34 to 47 °S. To map the precipitation isotope ratios across New Zealand, three years of integrated monthly precipitation samples were acquired from >50 stations. Conventional mean-annual precipitation δ(2)H and δ(18)O maps were produced by regressions using geographic and annual climate variables. Incomplete data and short-term variation in climate and precipitation sources limited the utility of this approach. We overcome these difficulties by calculating precipitation-weighted monthly climate parameters using national 5-km-gridded daily climate data. This data plus geographic variables were regressed to predict δ(2)H, δ(18)O, and d-excess at all sites. The procedure yields statistically-valid predictions of the isotope composition of precipitation (long-term average root mean square error (RMSE) for δ(18)O = 0.6 ‰; δ(2)H = 5.5 ‰); and monthly RMSE δ(18)O = 1.9 ‰, δ(2)H = 16 ‰. This approach has substantial benefits for studies that require the isotope composition of precipitation during specific time intervals, and may be further improved by comparison to daily and event-based precipitation samples as well as the use of back-trajectory calculations.

Cerium oxalate precipitation

International Nuclear Information System (INIS)

Chang, T.P.

1987-02-01

Cerium, a nonradioactive, common stand-in for plutonium in development work, has been used to simulate several plutonium precipitation processes at the Savannah River Laboratory. There are similarities between the plutonium trifluoride and the cerium oxalate precipitations in particle size and extent of plating, but not particle morphology. The equilibrium solubility, precipitation kinetics, particle size, extent of plating, and dissolution characteristics of cerium oxalate have been investigated. Interpretations of particle size and plating based on precipitation kinetics (i.e., nucleation and crystal growth) are presented. 16 refs., 7 figs., 6 tabs

Precipitation behavior and effect of new precipitated β phase in AZ80 magnesium alloy

Institute of Scientific and Technical Information of China (English)

TANG Wei; HAN En-hou; XU Yong-bo; LIU Lu

2006-01-01

Granular precipitate that was a new kind of β-Mg17Al12 phase found in aged AZ80 wrought Mg alloy at all aging temperature was studied. The structure and precipitation behavior of this granular β-Mg17Al12 precipitate were studied by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The effect of the granular precipitate on mechanical properties of AZ80 alloy was also studied. The new precipitate that was granular and nucleated both on grain boundaries (GBs) and twin boundaries, has the same crystal structure and lattice parameter as those of the continuous or discontinuous precipitated β-Mg17Al12. And the nucleation and growth of the granular precipitate are faster than those of the other two precipitates at higher temperatures (above 583 K), but are suppressed at lower temperatures (below 423 K). At lower temperatures, the discontinuous β-Mg17Al12 precipitates firstly and the granular β-Mg17Al12 precipitates after aged more than 40 h. The crack is easily nucleated on the phase boundaries of granular phase and matrix because of the weak binding force. As a result, the strength and ductility of AZ80 Mg alloy are decreased by the granular β-Mg17Al12 precipitate.

Serum Interleukin-6 in Patients with Burning Mouth Syndrome and Relationship with Depression and Perceived Pain

Directory of Open Access Journals (Sweden)

Qianming Chen

2007-01-01

Conclusions. Serum interleukin-6 in patients with burning mouth syndrome is decreased and negatively correlated to chronic pain. Both psychological and neuropathic disorders might act as precipitating factors in BMS etiopathogenesis.

Asymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments.

Science.gov (United States)

Wilcox, Kevin R; Shi, Zheng; Gherardi, Laureano A; Lemoine, Nathan P; Koerner, Sally E; Hoover, David L; Bork, Edward; Byrne, Kerry M; Cahill, James; Collins, Scott L; Evans, Sarah; Gilgen, Anna K; Holub, Petr; Jiang, Lifen; Knapp, Alan K; LeCain, Daniel; Liang, Junyi; Garcia-Palacios, Pablo; Peñuelas, Josep; Pockman, William T; Smith, Melinda D; Sun, Shanghua; White, Shannon R; Yahdjian, Laura; Zhu, Kai; Luo, Yiqi

2017-10-01

Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change

Stable exponential cosmological solutions with zero variation of G and three different Hubble-like parameters in the Einstein-Gauss-Bonnet model with a Λ-term

Energy Technology Data Exchange (ETDEWEB)

Ernazarov, K.K. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Ivashchuk, V.D. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); VNIIMS, Center for Gravitation and Fundamental Metrology, Moscow (Russian Federation)

2017-06-15

We consider a D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Λ. We restrict the metrics to diagonal cosmological ones and find for certain Λ a class of solutions with exponential time dependence of three scale factors, governed by three non-coinciding Hubble-like parameters H > 0, h{sub 1} and h{sub 2}, corresponding to factor spaces of dimensions m > 2, k{sub 1} > 1 and k{sub 2} > 1, respectively, with k{sub 1} ≠ k{sub 2} and D = 1 + m + k{sub 1} + k{sub 2}. Any of these solutions describes an exponential expansion of 3d subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics. (orig.)

Hepatorenal Syndrome: Aetiology, Diagnosis, and Treatment

Directory of Open Access Journals (Sweden)

G. Low

2015-01-01

Full Text Available Acute renal impairment is common in patients with chronic liver disease, occurring in approximately 19% of hospitalised patients with cirrhosis. A variety of types of renal impairment are recognised. The most important of these is the hepatorenal syndrome, a functional renal impairment due to circulatory and neurohormonal abnormalities that underpin cirrhosis. It is one of the most severe complications of cirrhosis with survival often measured in weeks to months. A variety of treatment options exist with early diagnosis and appropriate treatment providing the best hope for cure. This paper provides a comprehensive and up-to-date review of hepatorenal syndrome and lays out the topic according to the following sections: pathophysiology, historical developments, diagnostic criteria and limitations, epidemiology, precipitating factors, predictors, clinical and laboratory findings, prognosis, treatment options, prophylaxis, and conclusion.

Interannual variation of annual precipitation and urban effect on precipitation in the Beijing region

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The large scale character of the interannual variation of precipitation and the urban effect on local annual precipitation anomaly are investigated in this paper based on the 1960-2000 annual precipitation observations at 20 stations in the Beijing region. The results show that: the annual precipitation in the Beijing region possesses the large scale variation character with the linear trend of - 1.197/10 yr, which corresponds to a total reduction of 27.82 mm in annual precipitation in the 41 years; the local annual precipitation anomalies (percent of the normal 1960-2000) show a positive center near the urban area, i.e. urban precipitation island (UPI), whose intensity increases with the linear trend of 0. 6621%/10 yr, opposite to the interannual trend of large scale precipitation over the Beijing region; changes in the UPI are also associated with the intensity of synoptic processes of precipitation, and when the synoptic processes are strong (wet years), the intensity of UPI strengthens, while the synoptic processes are weak (dry years), and the UPI disappears in the Beijing region.

Visual hallucinations caused by Charles Bonnet Syndrome: A case ...

African Journals Online (AJOL)

had no cognitive impairment and was fully aware of the ... eration. Ms P's main complaint was visual hallucinations. ... brother in front of her eyes. She also displayed ... her would seem to develop a full beard. .... Beta blocking agents. 4.

Effective Assimilation of Global Precipitation

Science.gov (United States)

Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

2012-12-01

Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

Precipitation in partially stabilized zirconia

International Nuclear Information System (INIS)

Bansal, G.K.

1975-01-01

Transmission electron microscopy was used to study the substructure of partially stabilized ZrO 2 (PSZ) samples, i.e., 2-phase systems containing both cubic and monoclinic modifications of zirconia, after various heat treatments. Monoclinic ZrO 2 exists as (1) isolated grains within the polycrystalline aggregate (a grain- boundary phase) and (2) small plate-like particles within cubic grains. These intragranular precipitates are believed to contribute to the useful properties of PSZ via a form of precipitation hardening. These precipitates initially form as tetragonal ZrO 2 , with a habit plane parallel to the brace 100 brace matrix planes. The orientation relations between the tetragonal precipitates and the cubic matrix are brace 100 brace/sub matrix/ 2 parallel brace 100 brace /sub precipitate/ or (001)/sub precipitate/ and broken bracket 100 broken bracket/sub matrix/ 2 parallel broken bracket 100 broken bracket/sub precipitate/ or [001]/sub precipitate/. (U.S.)

Precipitation of {gamma}' phase in {delta}-precipitated Alloy 718 during deformation at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Nalawade, S.A. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sundararaman, M., E-mail: msraman@barc.gov.in [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, J.B.; Verma, A.; Kishore, R. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2010-05-15

Alloy 718 samples aged to precipitate only {delta} particles (with maximum volume fraction) when tensile deformed to fracture at elevated temperatures revealed precipitation of {gamma}' and {gamma}'' phases. The {gamma}' precipitation was found to precede the {gamma}'' phase precipitation unlike in the case of specimens subjected to standard ageing treatment where both the {gamma}' and the {gamma}'' phases precipitate simultaneously. This sequence is explained on the basis of the relative concentration of Al, Ti and Nb in the matrix of {delta} precipitated Alloy 718 microstructure. The precipitation sequence was consistent with the Cozar and Pineau's model that predicts such sequences on the basis of (Al + Ti) to Nb atom ratios.

Nongranulomatous anterior uveitis in a patient with Usher syndrome

OpenAIRE

Alzuhairy, Sultan Abdulaziz S.; Alfawaz, Abdullah

2013-01-01

A 34-year-old female with Usher syndrome, but no family history of similar illness, presented with complaints of vision reduction, redness, and photophobia. Biomicroscopic examination showed mildly injected conjunctivae bilateral, small, round keratic precipitates; bilateral +2 cells with no flare reaction in the anterior chamber; and bilateral posterior subcapsular cataracts. No associated posterior synechiae, angle neovascularization, or iris changes were detected; normal intraocular pressu...

Light deflection and Gauss-Bonnet theorem: definition of total deflection angle and its applications

Science.gov (United States)

Arakida, Hideyoshi

2018-05-01

In this paper, we re-examine the light deflection in the Schwarzschild and the Schwarzschild-de Sitter spacetime. First, supposing a static and spherically symmetric spacetime, we propose the definition of the total deflection angle α of the light ray by constructing a quadrilateral Σ^4 on the optical reference geometry M^opt determined by the optical metric \\bar{g}_{ij}. On the basis of the definition of the total deflection angle α and the Gauss-Bonnet theorem, we derive two formulas to calculate the total deflection angle α ; (1) the angular formula that uses four angles determined on the optical reference geometry M^opt or the curved (r, φ ) subspace M^sub being a slice of constant time t and (2) the integral formula on the optical reference geometry M^opt which is the areal integral of the Gaussian curvature K in the area of a quadrilateral Σ ^4 and the line integral of the geodesic curvature κ _g along the curve C_{Γ}. As the curve C_{Γ}, we introduce the unperturbed reference line that is the null geodesic Γ on the background spacetime such as the Minkowski or the de Sitter spacetime, and is obtained by projecting Γ vertically onto the curved (r, φ ) subspace M^sub. We demonstrate that the two formulas give the same total deflection angle α for the Schwarzschild and the Schwarzschild-de Sitter spacetime. In particular, in the Schwarzschild case, the result coincides with Epstein-Shapiro's formula when the source S and the receiver R of the light ray are located at infinity. In addition, in the Schwarzschild-de Sitter case, there appear order O(Lambda;m) terms in addition to the Schwarzschild-like part, while order O(Λ) terms disappear.

Few multiyear precipitation-reduction experiments find a shift in the productivity-precipitation relationship.

Science.gov (United States)

Estiarte, Marc; Vicca, Sara; Peñuelas, Josep; Bahn, Michael; Beier, Claus; Emmett, Bridget A; Fay, Philip A; Hanson, Paul J; Hasibeder, Roland; Kigel, Jaime; Kröel-Dulay, Gyorgy; Larsen, Klaus Steenberg; Lellei-Kovács, Eszter; Limousin, Jean-Marc; Ogaya, Romà; Ourcival, Jean-Marc; Reinsch, Sabine; Sala, Osvaldo E; Schmidt, Inger Kappel; Sternberg, Marcelo; Tielbörger, Katja; Tietema, Albert; Janssens, Ivan A

2016-07-01

Well-defined productivity-precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity-precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation-reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation-manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity-precipitation relationship downward the spatial fit. The majority of experiments (72%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation-reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with

The role of opioid antagonist efficacy and constitutive opioid receptor activity in the opioid withdrawal syndrome in mice

OpenAIRE

Navani, Dipesh M.; Sirohi, Sunil; Madia, Priyanka A.; Yoburn, Byron C.

2011-01-01

On the basis of efficacy, opioid antagonists are classified as inverse opioid agonists (e.g. naltrexone) or neutral opioid antagonists (e.g. 6β-naltrexol). This study examined the interaction between naltrexone and 6β-naltrexol in the precipitated opioid withdrawal syndrome in morphine dependent mice. Furthermore, the possible contribution of constitutive opioid receptor activity to precipitated withdrawal was evaluated using increasing levels of morphine dependence. In the first experiment, ...

Hepatorenal syndrome: diagnosis, treatment and prevention

DEFF Research Database (Denmark)

Israelsen, Mads Egerod; Gluud, Lise Lotte; Bendtsen, Flemming

2014-01-01

Cirrhosis, ascites and renal impairment are associated with high morbidity and mortality. The hepatorenal syndrome (HRS) is a type of renal failure that affects patients with cirrhosis and ascites. This paper provides an update on evidence-based interventions in HRS. A number of factors can...... precipitate HRS. The monitoring, prevention, early detection, and correct treatment of these are essential. Terlipressin combined with albumin is the first-line treatment of type 1 HRS. In type 2 HRS with refractory ascites, liver transplantation and TIPS should be considered....

Hepatorenalt syndrom: diagnose, behandling og forebyggelse

DEFF Research Database (Denmark)

Egerod Israelsen, Mads; Gluud, Lise Lotte; Bendtsen, Flemming

2013-01-01

Cirrhosis, ascites and renal impairment are associated with high morbidity and mortality. The hepatorenal syndrome (HRS) is a type of renal failure that affects patients with cirrhosis and ascites. This paper provides an update on evidence-based interventions in HRS. A number of factors can...... precipitate HRS. The monitoring, prevention, early detection, and correct treatment of these are essential. Terlipressin combined with albumin is the first-line treatment of type 1 HRS. In type 2 HRS with refractory ascites, liver transplantation and TIPS should be considered....

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

Science.gov (United States)

Fries, B.A.

1959-11-10

A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

Similarities and Improvements of GPM Dual-Frequency Precipitation Radar (DPR upon TRMM Precipitation Radar (PR in Global Precipitation Rate Estimation, Type Classification and Vertical Profiling

Directory of Open Access Journals (Sweden)

Jinyu Gao

2017-11-01

Full Text Available Spaceborne precipitation radars are powerful tools used to acquire adequate and high-quality precipitation estimates with high spatial resolution for a variety of applications in hydrological research. The Global Precipitation Measurement (GPM mission, which deployed the first spaceborne Ka- and Ku-dual frequency radar (DPR, was launched in February 2014 as the upgraded successor of the Tropical Rainfall Measuring Mission (TRMM. This study matches the swath data of TRMM PR and GPM DPR Level 2 products during their overlapping periods at the global scale to investigate their similarities and DPR’s improvements concerning precipitation amount estimation and type classification of GPM DPR over TRMM PR. Results show that PR and DPR agree very well with each other in the global distribution of precipitation, while DPR improves the detectability of precipitation events significantly, particularly for light precipitation. The occurrences of total precipitation and the light precipitation (rain rates < 1 mm/h detected by GPM DPR are ~1.7 and ~2.53 times more than that of PR. With regard to type classification, the dual-frequency (Ka/Ku and single frequency (Ku methods performed similarly. In both inner (the central 25 beams and outer swaths (1–12 beams and 38–49 beams of DPR, the results are consistent. GPM DPR improves precipitation type classification remarkably, reducing the misclassification of clouds and noise signals as precipitation type “other” from 10.14% of TRMM PR to 0.5%. Generally, GPM DPR exhibits the same type division for around 82.89% (71.02% of stratiform (convective precipitation events recognized by TRMM PR. With regard to the freezing level height and bright band (BB height, both radars correspond with each other very well, contributing to the consistency in stratiform precipitation classification. Both heights show clear latitudinal dependence. Results in this study shall contribute to future development of spaceborne

Two-stage precipitation of plutonium trifluoride

International Nuclear Information System (INIS)

Luerkens, D.W.

1984-04-01

Plutonium trifluoride was precipitated using a two-stage precipitation system. A series of precipitation experiments identified the significant process variables affecting precipitate characteristics. A mathematical precipitation model was developed which was based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter that can be used to control particle characteristics

STRONTIUM PRECIPITATION

Science.gov (United States)

McKenzie, T.R.

1960-09-13

A process is given for improving the precipitation of strontium from an aqueous phosphoric-acid-containing solution with nickel or cobalt ferrocyanide by simultaneously precipitating strontium or calcium phosphate. This is accomplished by adding to the ferrocyanide-containing solution calcium or strontium nitrate in a quantity to yield a concentration of from 0.004 to 0.03 and adjusting the pH of the solution to a value of above 8.

Global Precipitation Measurement (GPM) Mission: Precipitation Processing System (PPS) GPM Mission Gridded Text Products Provide Surface Precipitation Retrievals

Science.gov (United States)

Stocker, Erich Franz; Kelley, O.; Kummerow, C.; Huffman, G.; Olson, W.; Kwiatkowski, J.

2015-01-01

In February 2015, the Global Precipitation Measurement (GPM) mission core satellite will complete its first year in space. The core satellite carries a conically scanning microwave imager called the GPM Microwave Imager (GMI), which also has 166 GHz and 183 GHz frequency channels. The GPM core satellite also carries a dual frequency radar (DPR) which operates at Ku frequency, similar to the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar, and a new Ka frequency. The precipitation processing system (PPS) is producing swath-based instantaneous precipitation retrievals from GMI, both radars including a dual-frequency product, and a combined GMIDPR precipitation retrieval. These level 2 products are written in the HDF5 format and have many additional parameters beyond surface precipitation that are organized into appropriate groups. While these retrieval algorithms were developed prior to launch and are not optimal, these algorithms are producing very creditable retrievals. It is appropriate for a wide group of users to have access to the GPM retrievals. However, for researchers requiring only surface precipitation, these L2 swath products can appear to be very intimidating and they certainly do contain many more variables than the average researcher needs. Some researchers desire only surface retrievals stored in a simple easily accessible format. In response, PPS has begun to produce gridded text based products that contain just the most widely used variables for each instrument (surface rainfall rate, fraction liquid, fraction convective) in a single line for each grid box that contains one or more observations.This paper will describe the gridded data products that are being produced and provide an overview of their content. Currently two types of gridded products are being produced: (1) surface precipitation retrievals from the core satellite instruments GMI, DPR, and combined GMIDPR (2) surface precipitation retrievals for the partner constellation

Burning Mouth Syndrome and Menopause

Science.gov (United States)

Dahiya, Parveen; Kamal, Reet; Kumar, Mukesh; Niti; Gupta, Rajan; Chaudhary, Karun

2013-01-01

Menopause is a physiological process typically occurring in the fifth decade of life. One of the most annoying oral symptoms in this age group is the burning mouth syndrome (BMS), which may be defined as an intraoral burning sensation occurring in the absence of identifiable oral lesion or laboratory findings. Pain in burning mouth syndrome may be described as burning, tender, tingling, hot, scalding, and numb sensation in the oral mucosa. Multiple oral sites may be involved, but the anterior two-third part and the tip of tongue are most commonly affected site. There is no definite etiology for BMS other than the precipitating causative factors, and it is still considered idiopathic. Various treatment options like use of benzodiazepine, anti-depressants, analgesics, capsaicin, alpha lipoic acids, and cognitive behavioral therapy are found to be effective, but definite treatment is still unknown. The present article discusses some of the recent concepts of etiopathogenesis of BMS as well as the role of pharmacotherapeutic management in this disorder. PMID:23411996

Mechanisms, Risk Factors, and Management of Acquired Long QT Syndrome: A Comprehensive Review

Directory of Open Access Journals (Sweden)

Eleftherios M. Kallergis

2012-01-01

Full Text Available Long QT syndrome is characterized by prolongation of the corrected QT (QTc interval on the surface electrocardiogram and is associated with precipitation of torsade de pointes (TdP, a polymorphic ventricular tachycardia that may cause sudden death. Acquired long QT syndrome describes pathologic excessive prolongation of the QT interval, upon exposure to an environmental stressor, with reversion back to normal following removal of the stressor. The most common environmental stressor in acquired long QT syndrome is drug therapy. Acquired long QT syndrome is an important issue for clinicians and a significant public health problem concerning the large number of drugs with this adverse effect with a potentially fatal outcome, the large number of patients exposed to these drugs, and our inability to predict the risk for a given individual. In this paper, we focus on mechanisms underlying QT prolongation, risk factors for torsades de pointes and describe the short- and long-term treatment of acquired long QT syndrome.

Probability of occurrence of monthly and seasonal winter precipitation over Northwest India based on antecedent-monthly precipitation

Science.gov (United States)

Nageswararao, M. M.; Mohanty, U. C.; Dimri, A. P.; Osuri, Krishna K.

2018-05-01

Winter (December, January, and February (DJF)) precipitation over northwest India (NWI) is mainly associated with the eastward moving mid-latitude synoptic systems, western disturbances (WDs), embedded within the subtropical westerly jet (SWJ), and is crucial for Rabi (DJF) crops. In this study, the role of winter precipitation at seasonal and monthly scale over NWI and its nine meteorological subdivisions has been analyzed. High-resolution (0.25° × 0.25°) gridded precipitation data set of India Meteorological Department (IMD) for the period of 1901-2013 is used. Results indicated that the seasonal precipitation over NWI is below (above) the long-term mean in most of the years, when precipitation in any of the month (December/January/February) is in deficit (excess). The contribution of December precipitation (15-20%) to the seasonal (DJF) precipitation is lesser than January (35-40%) and February (35-50%) over all the subdivisions. December (0.60), January (0.57), and February (0.69) precipitation is in-phase (correlation) with the corresponding winter season precipitation. However, January precipitation is not in-phase with the corresponding December (0.083) and February (-0.03) precipitation, while December is in-phase with the February (0.21). When monthly precipitation (December or January or December-January or February) at subdivision level over NWI is excess (deficit); then, the probability of occurrence of seasonal excess (deficit) precipitation is high (almost nil). When antecedent-monthly precipitation is a deficit or excess, the probability of monthly (January or February or January + February) precipitation to be a normal category is >60% over all the subdivisions. This study concludes that the December precipitation is a good indicator to estimate the performance of January, February, January-February, and the seasonal (DJF) precipitation.

An Improved Plutonium Trifluoride Precipitation Flowsheet

Energy Technology Data Exchange (ETDEWEB)

Harmon, H.D.

2001-06-26

This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process.

An Improved Plutonium Trifluoride Precipitation Flowsheet

International Nuclear Information System (INIS)

Harmon, H.D.

2001-01-01

This report discusses results of the plutonium trifluoride two-stage precipitation study. A series of precipitation experiments was used to identify the significant process variables affecting precipitation performance. A mathematical model of the precipitation process was developed which is based on the formation of plutonium fluoride complexes. The precipitation model relates all process variables, in a single equation, to a single parameter which can be used to control the performance of the plutonium trifluoride precipitation process. Recommendations have been made which will optimize the FB-Line plutonium trifluoride precipitation process

On the problem of isometry of a hypersurface preserving mean ...

Indian Academy of Sciences (India)

study and it is described on a hypersurface. It is proved that, non-minimal hypersur- face in Rn+1 with no umbilical points is a Bonnet hypersurface if and only if it has an. A-net. Keywords. Bonnet hypersurface; Bonnet associate; isometry; mean curvature; preserving; Bonnet curve; A-net. 1. Introduction. The isometry problem ...

TCA precipitation.

Science.gov (United States)

Koontz, Laura

2014-01-01

Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein). © 2014 Elsevier Inc. All rights reserved.

Stable exponential cosmological solutions with 3- and l-dimensional factor spaces in the Einstein-Gauss-Bonnet model with a Λ-term

Energy Technology Data Exchange (ETDEWEB)

Ivashchuk, V.D. [Peoples' Friendship University of Russia (RUDN University), Institute of Gravitation and Cosmology, Moscow (Russian Federation); Center for Gravitation and Fundamental Metrology, VNIIMS, Moscow (Russian Federation); Kobtsev, A.A. [Institute for Nuclear Research, RAS, Moscow (Russian Federation)

2018-02-15

A D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Λ is studied. We assume the metrics to be diagonal cosmological ones. For certain fine-tuned Λ, we find a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters H > 0 and h, corresponding to factor spaces of dimensions 3 and l > 2, respectively and D = 1 + 3 + l. The fine-tuned Λ = Λ(x, l, α) depends upon the ratio h/H = x, l and the ratio α = α{sub 2}/α{sub 1} of two constants (α{sub 2} and α{sub 1}) of the model. For fixed Λ, α and l > 2 the equation Λ(x, l, α) = Λ is equivalent to a polynomial equation of either fourth or third order and may be solved in radicals (the example l = 3 is presented). For certain restrictions on x we prove the stability of the solutions in a class of cosmological solutions with diagonal metrics. A subclass of solutions with small enough variation of the effective gravitational constant G is considered. It is shown that all solutions from this subclass are stable. (orig.)

Sleep Disturbance in Children with Rett Syndrome: A Qualitative Investigation of the Parental Experience

Science.gov (United States)

McDougall, Allyson; Kerr, Alison M.; Espie, Colin A.

2005-01-01

Background: Sleep problems in children with intellectual disability can be precipitated and maintained by intrinsic and external factors. The present study comprised a qualitative investigation of the experiences of parents of children with Rett syndrome, a neurodevelopmental disorder where sleep disturbance is common. Method: Audio-taped…

Radar-Derived Quantitative Precipitation Estimation Based on Precipitation Classification

Directory of Open Access Journals (Sweden)

Lili Yang

2016-01-01

Full Text Available A method for improving radar-derived quantitative precipitation estimation is proposed. Tropical vertical profiles of reflectivity (VPRs are first determined from multiple VPRs. Upon identifying a tropical VPR, the event can be further classified as either tropical-stratiform or tropical-convective rainfall by a fuzzy logic (FL algorithm. Based on the precipitation-type fields, the reflectivity values are converted into rainfall rate using a Z-R relationship. In order to evaluate the performance of this rainfall classification scheme, three experiments were conducted using three months of data and two study cases. In Experiment I, the Weather Surveillance Radar-1988 Doppler (WSR-88D default Z-R relationship was applied. In Experiment II, the precipitation regime was separated into convective and stratiform rainfall using the FL algorithm, and corresponding Z-R relationships were used. In Experiment III, the precipitation regime was separated into convective, stratiform, and tropical rainfall, and the corresponding Z-R relationships were applied. The results show that the rainfall rates obtained from all three experiments match closely with the gauge observations, although Experiment II could solve the underestimation, when compared to Experiment I. Experiment III significantly reduced this underestimation and generated the most accurate radar estimates of rain rate among the three experiments.

Precipitation Sedimentation and Advection in GFS

Science.gov (United States)

Sun, R.; Tallapragada, V.

2016-12-01

Zhao and Carr microphysics scheme as implemented in the NCEP Global Forecasting System (GFS) predicts only the total cloud condensate (cloud water or ice). The precipitation generated in the column fall to the ground instantly. This mean precipitation sedimentation and advection are not considered. As resolution increases the lack of the two physical processes creates problems. The slowly falling precipitation (snow) falls to the wrong surface grid box, which may have led to the observed spotty-precipitation pattern. To solve the problem two prognositic variables, snow and rain, are added. Addition of the two precipitation variable allows their advection. The corresponding sedimentation process are also added. In this study we examine the effect of precipitation advection and sedimentation on the precipitation pattern, associated precipitation skills and clouds.

Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

Science.gov (United States)

Li, Xin; Babovic, Vladan

2017-04-01

Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have

Hepatorenal Syndrome: Are We Doing Better?

Directory of Open Access Journals (Sweden)

Florence Wong

2004-01-01

Full Text Available This is a retrospective study assessing the accuracy of diagnosis, clinical features and outcome of patients coded with a medical record diagnosis of hepatorenal syndrome (HRS between 1988 and 1998 in a tertiary care centre in Canada. The authors found that, of the 46 patients whose medical records revealed a diagnosis of HRS, only 27 patients (59% fulfilled the criteria for the diagnosis of HRS defined by the International Ascites Club (IAC (1. Most patients with HRS were middle-aged men with decompensated alcoholic cirrhosis, jaundice and hepatic encephalopathy. Infection (48%, gastrointestinal bleeding (33% and overly aggressive paracentesis (27% were the major precipitants of renal failure. Once HRS developed, the mortality rate was high (93%, with multiorgan failure being the most common cause of death. The authors concluded that diagnostic accuracy is paramount for studies of HRS. In addition, decompensated alcoholic cirrhosis remains the main predisposing factor for HRS, with various other factors precipitating its development.

Centrifugal precipitation chromatography

Science.gov (United States)

Ito, Yoichiro; Lin, Qi

2009-01-01

Centrifugal precipitation chromatography separates analytes according their solubility in ammonium sulfate (AS) solution and other precipitants. The separation column is made from a pair of long spiral channels partitioned with a semipermeable membrane. In a typical separation, concentrated ammonium sulfate is eluted through one channel while water is eluted through the other channel in the opposite direction. The countercurrent process forms an exponential AS concentration gradient through the water channel. Consequently, protein samples injected into the water channel is subjected to a steadily increasing AS concentration and at the critical AS concentration they are precipitated and deposited in the channel bed by the centrifugal force. Then the chromatographic separation is started by gradually reducing the AS concentration in the AS channel which lowers the AS gradient concentration in the water channel. This results in dissolution of deposited proteins which are again precipitated at an advanced critical point as they move through the channel. Consequently, proteins repeat precipitation and dissolution through a long channel and finally eluted out from the column in the order of their solubility in the AS solution. The present method has been successfully applied to a number of analytes including human serum proteins, recombinant ketosteroid isomerase, carotenoid cleavage enzymes, plasmid DNA, polysaccharide, polymerized pigments, PEG-protein conjugates, etc. The method is capable to single out the target species of proteins by affinity ligand or immunoaffinity separation. PMID:19541553

Response to social challenge in young bonnet (Macaca radiata) and pigtail (Macaca nemestrina) macaques is related to early maternal experiences.

Science.gov (United States)

Weaver, Ann; Richardson, Rebecca; Worlein, Julie; De Waal, Frans; Laudenslager, Mark

2004-04-01

Previous experience affects how young primates respond to challenging social situations. The present retrospective study looked at one aspect of early experience, the quality of the mother-infant relationship, to determine its relationship to young bonnet and pigtail macaques' responses to two social challenges: temporary maternal separation at 5-6 months and permanent transfer to an unfamiliar peer group at 16-17 months. Relationship quality was measured quantitatively on 30 macaque mother-infant pairs with the Relationship Quality Index (RQI), the ratio of relative affiliation to relative agonism as previously applied to capuchin monkeys. Infants with high RQI values had amicable mother-infant relationships and infants with low RQI values had agonistic mother-infant relationships. Young monkeys with amicable and agonistic relationships showed consistent differences in behavior before, during, and after each social challenge, supporting the hypothesis that juveniles from amicable mother-infant relationships based on the RQI coped more effectively with social challenges than did juveniles from agonistic mother-infant relationships. Results suggest 1) characteristic amicability or agonism in early mother-offspring macaque relationships has the potential to influence offspring behavior in tense social contexts and 2) the RQI is useful as one of a coordinated suite of methods for studying the development of social skills. Copyright 2004 Wiley-Liss, Inc.

Three Cases with Visual Hallucinations following Combined Ocular and Occipital Damage

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Bogusław Paradowski

2013-01-01

Full Text Available Charles Bonnet syndrome is an underrecognized disease that involves visual hallucinations in visually impaired patients. We present the cases of three patients who experienced complex visual hallucinations following various pathomechanisms. In two cases, diagnosis showed coexistence of occipital lobe damage with ocular damage, while in the third case it showed occipital lobe damage with retrobulbar optic neuritis. Theories of pathogenesis and the neuroanatomical basis of complex visual hallucinations are discussed and supported by literature review.

The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present)

Science.gov (United States)

Adler, Robert F.; Huffman, George J.; Chang, Alfred; Ferraro, Ralph; Xie, Ping-Ping; Janowiak, John; Rudolf, Bruno; Schneider, Udo; Curtis, Scott; Bolvin, David

2003-01-01

The Global Precipitation Climatology Project (GPCP) Version 2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.5 degrees x 2.5 degrees latitude-longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit-satellite infrared data, and rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The data set is extended back into the premicrowave era (before 1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the raingauge analysis. This monthly analysis is the foundation for the GPCP suite of products including those at finer temporal resolution, satellite estimate, and error estimates for each field. The 23-year GPCP climatology is characterized, along with time and space variations of precipitation.

Clinical and ultrasound features in patients with intersection syndrome or de Quervain's disease.

Science.gov (United States)

Sato, J; Ishii, Y; Noguchi, H

2016-02-01

We investigated the demographic characteristics of patients who were diagnosed with intersection syndrome and also investigated the dominance of the affected hand, duration of symptoms and any precipitating factor for pain of the wrist. These features were compared with patients who had de Quervain's disease. Ultrasonography was used to confirm the clinical diagnosis. Intersection syndrome occurred more frequently in men and in the dominant hand than de Quervain's disease when all the patients were compared and when peripartum women were excluded. It occurred at a younger age than de Quervain's disease only when the comparison excluded peripartum women. Patients with intersection syndrome presented with a much shorter duration of symptoms. These results were consistent with previous reports about occupational factors in intersection syndrome, and might be helpful in the understanding of epidemiological difference between the two conditions. Level 3. © The Author(s) 2015.

Satellite-Based Precipitation Datasets

Science.gov (United States)

Munchak, S. J.; Huffman, G. J.

2017-12-01

Of the possible sources of precipitation data, those based on satellites provide the greatest spatial coverage. There is a wide selection of datasets, algorithms, and versions from which to choose, which can be confusing to non-specialists wishing to use the data. The International Precipitation Working Group (IPWG) maintains tables of the major publicly available, long-term, quasi-global precipitation data sets (http://www.isac.cnr.it/ ipwg/data/datasets.html), and this talk briefly reviews the various categories. As examples, NASA provides two sets of quasi-global precipitation data sets: the older Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) and current Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) mission (IMERG). Both provide near-real-time and post-real-time products that are uniformly gridded in space and time. The TMPA products are 3-hourly 0.25°x0.25° on the latitude band 50°N-S for about 16 years, while the IMERG products are half-hourly 0.1°x0.1° on 60°N-S for over 3 years (with plans to go to 16+ years in Spring 2018). In addition to the precipitation estimates, each data set provides fields of other variables, such as the satellite sensor providing estimates and estimated random error. The discussion concludes with advice about determining suitability for use, the necessity of being clear about product names and versions, and the need for continued support for satellite- and surface-based observation.

Kinetics of cadmium hydroxide precipitation

International Nuclear Information System (INIS)

Patterson, J.W.; Marani, D.; Luo, B.; Swenson, P.

1987-01-01

This paper presents some preliminary results on the kinetics of Cd(OH)/sub 2/ precipitation, both in the absence and the presence of citric acid as an inhibiting agent. Batch and continuous stirred tank reactor (CSTR) precipitation studies are performed by mixing equal volumes of NaOH and Cd(NO/sub 3/)/sub 2/ solutions, in order to avoid localized supersaturation conditions. The rate of metal removal from the soluble phase is calculated from the mass balance for the CSTR precipitation tests. In addition, precipitation kinetics are studied in terms of nucleation and crystal growth rates, by means of a particle counter that allows a population balance analysis for the precipitation reactor at steady state conditions

Two-stage precipitation of neptunium (IV) oxalate

International Nuclear Information System (INIS)

Luerkens, D.W.

1983-07-01

Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

Locomotor recovery after spinal cord hemisection/contusion injures in bonnet monkeys: footprint testing--a minireview.

Science.gov (United States)

Rangasamy, Suresh Babu

2013-07-01

Spinal cord injuries usually produce loss or impairment of sensory, motor and reflex function below the level of damage. In the absence of functional regeneration or manipulations that promote regeneration, spontaneous improvements in motor functions occur due to the activation of multiple compensatory mechanisms in animals and humans following the partial spinal cord injury. Many studies were performed on quantitative evaluation of locomotor recovery after induced spinal cord injury in animals using behavioral tests and scoring techniques. Although few studies on rodents have led to clinical trials, it would appear imperative to use nonhuman primates such as macaque monkeys in order to relate the research outcomes to recovery of functions in humans. In this review, we will discuss some of our research evidences concerning the degree of spontaneous recovery in bipedal locomotor functions of bonnet monkeys that underwent spinal cord hemisection/contusion lesions. To our knowledge, this is the first report to discuss on the extent of spontaneous recovery in bipedal locomotion of macaque monkeys through the application of footprint analyzing technique. In addition, the results obtained were compared with the published data on recovery of quadrupedal locomotion of spinally injured rodents. We propose that the mechanisms underlying spontaneous recovery of functions in spinal cord lesioned monkeys may be correlated to the mature function of spinal pattern generator for locomotion under the impact of residual descending and afferent connections. Moreover, based on analysis of motor functions observed in locomotion in these subjected monkeys, we understand that spinal automatism and development of responses by afferent stimuli from outside the cord could possibly contribute to recovery of paralyzed hindlimbs. This report also emphasizes the functional contribution of progressive strengthening of undamaged nerve fibers through a collateral sprouts/synaptic plasticity formed

Modeling winter precipitation over the Juneau Icefield, Alaska, using a linear model of orographic precipitation

Science.gov (United States)

Roth, Aurora; Hock, Regine; Schuler, Thomas V.; Bieniek, Peter A.; Pelto, Mauri; Aschwanden, Andy

2018-03-01

Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale winter precipitation from a regional climate model over the Juneau Icefield, one of the largest ice masses in North America (>4000 km2), for the period 1979-2013. The LT model is physically-based yet computationally efficient, combining airflow dynamics and simple cloud microphysics. The resulting 1 km resolution precipitation fields show substantially reduced precipitation on the northeastern portion of the icefield compared to the southwestern side, a pattern that is not well captured in the coarse resolution (20 km) WRF data. Net snow accumulation derived from the LT model precipitation agrees well with point observations across the icefield. To investigate the robustness of the LT model results, we perform a series of sensitivity experiments varying hydrometeor fall speeds, the horizontal resolution of the underlying grid, and the source of the meteorological forcing data. The resulting normalized spatial precipitation pattern is similar for all sensitivity experiments, but local precipitation amounts vary strongly, with greatest sensitivity to variations in snow fall speed. Results indicate that the LT model has great potential to provide improved spatial patterns of winter precipitation for glacier mass balance modeling purposes in complex terrain, but ground observations are necessary to constrain model parameters to match total amounts.

Modelled Precipitation Over Greenland

Data.gov (United States)

National Aeronautics and Space Administration — This data set includes the annual total precipitation from 1985 to 1999 and monthly total precipitation from January 1985 to December 1999. The data is derived from...

Electrical operation of electrostatic precipitators

CERN Document Server

Parker, Ken

2003-01-01

The electrostatic precipitator remains on of the most cost effective means of controlling the emission of particulates from most industrial processes. This book will be of interest to both users and suppliers of electrostatic precipitators as well as advanced students on environmental based courses. The author identifies the physical and engineering basis for the development of electrical equipment for electrostatic precipitators and thoroughly explores the technological factors which optimize the efficiency of the precipitator and hence minimize emissions, as well as future developments in th

Are black holes in alternative theories serious astrophysical candidates? The case for Einstein-dilaton-Gauss-Bonnet black holes

International Nuclear Information System (INIS)

Pani, Paolo; Cardoso, Vitor

2009-01-01

It is generally accepted that Einstein's theory will get some as yet unknown corrections, possibly large in the strong-field regime. An ideal place to look for these modifications is in the vicinities of compact objects such as black holes. Here, we study dilatonic black holes, which arise in the framework of Gauss-Bonnet couplings and one-loop corrected four-dimensional effective theory of heterotic superstrings at low energies. These are interesting objects as a prototype for alternative, yet well-behaved gravity theories: they evade the 'no-hair' theorem of general relativity but were proven to be stable against radial perturbations. We investigate the viability of these black holes as astrophysical objects and try to provide some means to distinguish them from black holes in general relativity. We start by extending previous works and establishing the stability of these black holes against axial perturbations. We then look for solutions of the field equations describing slowly rotating black holes and study geodesic motion around this geometry. Depending on the values of mass, dilaton charge, and angular momentum of the solution, one can have differences in the innermost-stable-circular-orbit location and orbital frequency, relative to black holes in general relativity. In the most favorable cases, the difference amounts to a few percent. Given the current state-of-the-art, we discuss the difficulty of distinguishing the correct theory of gravity from electromagnetic observations or even with gravitational-wave detectors.

Precipitates in irradiated Zircaloy

International Nuclear Information System (INIS)

Chung, H.M.

1985-10-01

Precipitates in high-burnup (>20 MWd/kg U) Zircaloy spent-fuel cladding discharged from commercial boiling- and pressurized-water reactors have been characterized by TEM-HVEM. Three classes of primary precipitates were observed in the irradiated Zircaloys: Zr 3 O (2 to 6 nm), cubic-ZrO 2 (greater than or equal to 10 nm), and delta-hydride (35 to 100 nm). The former two precipitations appears to be irradiation induced in nature. Zr(Fe/sub x/Cr/sub 1-x/) 2 and Zr 2 (Fe/sub x/Ni/sub 1-x/) intermetallics, which are the primary precipitates in unirradiated Zircaloys, were largely dissolved after the high burnup. It seems, therefore, that the influence of the size and distribution of the intermetallics on the corrosion behavior may be quite different for the irradiated Zircaloys

Heavy metal immobilization via microbially induced carbonate precipitation and co-precipitation

Science.gov (United States)

Lauchnor, E. G.; Stoick, E.

2017-12-01

Microbially induced CaCO3 precipitation (MICP) has been successfully used in applications such as porous media consolidation and sealing of leakage pathways in the subsurface, and it has the potential to be used for remediation of metal and radionuclide contaminants in surface and groundwater. In this work, MICP is investigated for removal of dissolved heavy metals from contaminated mine discharge water via co-precipitation in CaCO3 or formation of other metal carbonates. The bacterially catalyzed hydrolysis of urea produces inorganic carbon and ammonium and increases pH and the saturation index of carbonate minerals to promote precipitation of CaCO3. Other heavy metal cations can be co-precipitated in CaCO3 as impurities or by replacing Ca2+ in the crystal lattice. We performed laboratory batch experiments of MICP in alkaline mine drainage sampled from an abandoned mine site in Montana and containing a mixture of heavy metals at near neutral pH. Both a model bacterium, Sporosarcina pasteurii, and a ureolytic bacterium isolated from sediments on the mine site were used to promote MICP. Removal of dissolved metals from the aqueous phase was determined via inductively coupled plasma mass spectrometry and resulting precipitates were analyzed via electron microscopy and energy dispersive x-ray spectroscopy (EDX). Both S. pasteurii and the native ureolytic isolate demonstrated ureolysis, increased the pH and promoted precipitation of CaCO3 in batch tests. MICP by the native bacterium reduced concentrations of the heavy metals zinc, copper, cadmium, nickel and manganese in the water. S. pasteurii was also able to promote MICP, but with less removal of dissolved metals. Analysis of precipitates revealed calcium carbonate and phosphate minerals were likely present. The native isolate is undergoing identification via 16S DNA sequencing. Ongoing work will evaluate biofilm formation and MICP by the isolate in continuous flow, gravel-filled laboratory columns. This research

Precipitation and Hardening in Magnesium Alloys

Science.gov (United States)

Nie, Jian-Feng

2012-11-01

Magnesium alloys have received an increasing interest in the past 12 years for potential applications in the automotive, aircraft, aerospace, and electronic industries. Many of these alloys are strong because of solid-state precipitates that are produced by an age-hardening process. Although some strength improvements of existing magnesium alloys have been made and some novel alloys with improved strength have been developed, the strength level that has been achieved so far is still substantially lower than that obtained in counterpart aluminum alloys. Further improvements in the alloy strength require a better understanding of the structure, morphology, orientation of precipitates, effects of precipitate morphology, and orientation on the strengthening and microstructural factors that are important in controlling the nucleation and growth of these precipitates. In this review, precipitation in most precipitation-hardenable magnesium alloys is reviewed, and its relationship with strengthening is examined. It is demonstrated that the precipitation phenomena in these alloys, especially in the very early stage of the precipitation process, are still far from being well understood, and many fundamental issues remain unsolved even after some extensive and concerted efforts made in the past 12 years. The challenges associated with precipitation hardening and age hardening are identified and discussed, and guidelines are outlined for the rational design and development of higher strength, and ultimately ultrahigh strength, magnesium alloys via precipitation hardening.

PRECIPITATION OF PROTACTINIUM

Science.gov (United States)

Moore, R.L.

1958-07-15

An lmprovement in the separation of protactinium from aqueous nitric acid solutions is described. 1t covers the use of lead dioxide and tin dioxide as carrier precipitates for the protactinium. In carrying out the process, divalent lead or divalent tin is addcd to the solution and oxidized, causing formation of a carrier precipitate of lead dioxide or stannic oxide, respectively.

[2016 review on catastrophic antiphospholipid syndrome].

Science.gov (United States)

Costedoat-Chalumeau, Nathalie; Coutte, Laetitia; Le Guern, Véronique; Morel, Nathalie; Leroux, Gaelle; Paule, Romain; Mouthon, Luc; Piette, Jean-Charles

2016-12-01

The catastrophic antiphospholipid syndrome (CAPS) develops in at least 1% of patients with antiphospholipid syndrome, either primary or associated with systemic lupus erythematosus. CAPS reveals the antiphospholipid syndrome in about 50% of cases. The CAPS is characterized by rapidly-progressive widespread thromboses mainly affecting the microvasculature in the presence of antiphospholipid antibodies. In a few days, the patients develop multiorgan failure with renal insufficiency with severe hypertension, pulmonary, cerebral, cardiac, digestive and/or cutaneous involvement. The vital prognosis is frequently engaged. CAPS is often precipitated by infectious diseases, surgical procedures and/or withdrawal or modification of the anticoagulation. CAPS overall mortality rate has decreased and is currently below 30%. The main differential diagnoses are other thrombotic microangiopathies, and heparin-induced thrombocytopenia. The treatment of CAPS consists of the association of anticoagulation and steroids, plus plasma exchange and/or intravenous immunoglobulins. Cyclophosphamide is added only in patients with active systemic lupus erythematosus. The potential contribution of some additional therapies (rituximab, eculizumab or sirolimus) needs to be assessed. The prevention of CAPS is essential and is based upon the adequate management of the perioperative period when surgery cannot be avoided, the prompt treatment and the prevention with immunization of infections and the education of patients with antiphospholipid syndrome, especially for the management of oral anticoagulants. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Development of precipitator of fluid film type

International Nuclear Information System (INIS)

Liu Yupu

1987-01-01

The precipitator of fluid film type is developed for the determination of fuel element cladding failure of water-cooled reactor. It integrates the scrubber, precipitator and detector. The jet of element cooling water automatically circulates carrier gas and the flow water film transfers precipitates onto the surface of centre electrode. Three different types are designed. On the special test loop, the uranium sample pellets of simulating cladding failure is measured. The sensitivity of precipitators, saturated precipitation voltage, incremental speed of signal, speed of driving out precipitates and the contents of the precipitates are determined. The test shows that the precipitators are highly sensitive, reliable, cheap and easy to operate

Migraine, cerebrovascular disease and the metabolic syndrome

Directory of Open Access Journals (Sweden)

Alexandra J Sinclair

2012-01-01

Full Text Available Evidence is emerging that migraine is not solely a headache disorder. Observations that ischemic stroke could occur in the setting of a migraine attack, and that migraine headaches could be precipitated by cerebral ischemia, initially highlighted a possibly association between migraine and cerebrovascular disease. More recently, large population-based studies that have demonstrated that migraineurs are at increased risk of stroke outside the setting of a migraine attack have prompted the concept that migraine and cerebrovascular disease are comorbid conditions. Explanations for this association are numerous and widely debated, particularly as the comorbid association does not appear to be confined to the cerebral circulation as cardiovascular and peripheral vascular disease also appear to be comorbid with migraine. A growing body of evidence has also suggested that migraineurs are more likely to be obese, hypertensive, hyperlipidemic and have impaired insulin sensitivity, all features of the metabolic syndrome. The comorbid association between migraine and cerebrovascular disease may consequently be explained by migraineurs having the metabolic syndrome and consequently being at increased risk of cerebrovascular disease. This review will summarise the salient evidence suggesting a comorbid association between migraine, cerebrovascular disease and the metabolic syndrome.

Global Precipitation Measurement. Report 7; Bridging from TRMM to GPM to 3-Hourly Precipitation Estimates

Science.gov (United States)

Shepherd, J. Marshall; Smith, Eric A.; Adams, W. James (Editor)

2002-01-01

Historically, multi-decadal measurements of precipitation from surface-based rain gauges have been available over continents. However oceans remained largely unobserved prior to the beginning of the satellite era. Only after the launch of the first Defense Meteorological Satellite Program (DMSP) satellite in 1987 carrying a well-calibrated and multi-frequency passive microwave radiometer called Special Sensor Microwave/Imager (SSM/I) have systematic and accurate precipitation measurements over oceans become available on a regular basis; see Smith et al. (1994, 1998). Recognizing that satellite-based data are a foremost tool for measuring precipitation, NASA initiated a new research program to measure precipitation from space under its Mission to Planet Earth program in the 1990s. As a result, the Tropical Rainfall Measuring Mission (TRMM), a collaborative mission between NASA and NASDA, was launched in 1997 to measure tropical and subtropical rain. See Simpson et al. (1996) and Kummerow et al. (2000). Motivated by the success of TRMM, and recognizing the need for more comprehensive global precipitation measurements, NASA and NASDA have now planned a new mission, i.e., the Global Precipitation Measurement (GPM) mission. The primary goal of GPM is to extend TRMM's rainfall time series while making substantial improvements in precipitation observations, specifically in terms of measurement accuracy, sampling frequency, Earth coverage, and spatial resolution. This report addresses four fundamental questions related to the transition from current to future global precipitation observations as denoted by the TRMM and GPM eras, respectively.

Self-organizing map network-based precipitation regionalization for the Tibetan Plateau and regional precipitation variability

Science.gov (United States)

Wang, Nini; Yin, Jianchuan

2017-12-01

A precipitation-based regionalization for the Tibetan Plateau (TP) was investigated for regional precipitation trend analysis and frequency analysis using data from 1113 grid points covering the period 1900-2014. The results utilizing self-organizing map (SOM) network suggest that four clusters of precipitation coherent zones can be identified, including the southwestern edge, the southern edge, the southeastern region, and the north central region. Regionalization results of the SOM network satisfactorily represent the influences of the atmospheric circulation systems such as the East Asian summer monsoon, the south Asian summer monsoon, and the mid-latitude westerlies. Regionalization results also well display the direct impacts of physical geographical features of the TP such as orography, topography, and land-sea distribution. Regional-scale annual precipitation trend as well as regional differences of annual and seasonal total precipitation were investigated by precipitation index such as precipitation concentration index (PCI) and Standardized Anomaly Index (SAI). Results demonstrate significant negative long-term linear trends in southeastern TP and the north central part of the TP, indicating arid and semi-arid regions in the TP are getting drier. The empirical mode decomposition (EMD) method shows an evolution of the main cycle with 4 and 12 months for all the representative grids of four sub-regions. The cross-wavelet analysis suggests that predominant and effective period of Indian Ocean Dipole (IOD) on monthly precipitation is around ˜12 months, except for the representative grid of the northwestern region.

Burning mouth syndrome and menopause

Directory of Open Access Journals (Sweden)

Parveen Dahiya

2013-01-01

Full Text Available Menopause is a physiological process typically occurring in the fifth decade of life. One of the most annoying oral symptoms in this age group is the burning mouth syndrome (BMS, which may be defined as an intraoral burning sensation occurring in the absence of identifiable oral lesion or laboratory findings. Pain in burning mouth syndrome may be described as burning, tender, tingling, hot, scalding, and numb sensation in the oral mucosa. Multiple oral sites may be involved, but the anterior two-third part and the tip of tongue are most commonly affected site. There is no definite etiology for BMS other than the precipitating causative factors, and it is still considered idiopathic. Various treatment options like use of benzodiazepine, anti-depressants, analgesics, capsaicin, alpha lipoic acids, and cognitive behavioral therapy are found to be effective, but definite treatment is still unknown. The present article discusses some of the recent concepts of etiopathogenesis of BMS as well as the role of pharmacotherapeutic management in this disorder.

Nongranulomatous anterior uveitis in a patient with Usher syndrome.

Science.gov (United States)

Alzuhairy, Sultan Abdulaziz S; Alfawaz, Abdullah

2013-10-01

A 34-year-old female with Usher syndrome, but no family history of similar illness, presented with complaints of vision reduction, redness, and photophobia. Biomicroscopic examination showed mildly injected conjunctivae bilateral, small, round keratic precipitates; bilateral +2 cells with no flare reaction in the anterior chamber; and bilateral posterior subcapsular cataracts. No associated posterior synechiae, angle neovascularization, or iris changes were detected; normal intraocular pressures were obtained. Fundus examination demonstrated waxy pallor of both optic nerves, marked vasoconstriction in retinal vessels, and retinal bone spicule pigment formation, with a normal macula. Electroretinography confirmed the diagnosis of retinitis pigmentosa, optical coherent tomography was normal and otolaryngology consultation was conducted. To our knowledge, an association between Usher syndrome and bilateral nongranulomatous anterior uveitis has not been previously reported, and our purpose is to report this association.

Intercomparison of spaceborne precipitation radars and its applications in examining precipitation-topography relationships in the Tibetan Plateau

Science.gov (United States)

Tang, G.; Gao, J.; Long, D.

2017-12-01

Precipitation is one of the most important components in the water and energy cycles. Spaceborne radars are considered the most direct technology for observing precipitation from space since 1998. This study compares and evaluates the only three existing spaceborne precipitation radars, i.e., the Ku-band precipitation radar (TRMM PR), the W-band Cloud Profiling Radar (CloudSat CPR), and the Ku/Ka-band Dual-frequency Precipitation Radar (GPM DPR). In addition, TRMM PR and GPM DPR are evaluated against hourly rain gauge data in Mainland China. The Tibetan Plateau (TP) is known as the Earth's third pole where precipitation is affected profoundly by topography. However, ground gauges are extremely sparse in the TP, and spaceborne radars can provide valuable data with relatively high accuracy. The relationships between precipitation and topography over the TP are investigated using 17-year TRMM PR data and 2-year GPM DPR data, in combination with rain gauge data. Results indicate that: (1) DPR and PR agree with each other and correlate very well with gauges in Mainland China. DPR improves light precipitation detectability significantly compared with PR. However, DPR high sensitivity scans (HS) deviates from DPR normal and matched scans (NS and MS) and PR in the comparison based on global coincident events and rain gauges in China; (2) CPR outperforms the other two radars in terms of light precipitation detection. In terms of global snowfall estimation, DPR and CPR show very different global snowfall distributions originating from different frequencies, retrieval algorithms, and sampling characteristics; and (3) Precipitation generally decreases exponentially with increasing elevation in the TP. The precipitation-topography relationships are regressed using exponential fitting in seventeen river basins in the TP with good coefficients of determination. Due to the short time span of GPM DPR, the relationships based on GPM DPR data are less robust than those derived from

STAMMEX high resolution gridded daily precipitation dataset over Germany: a new potential for regional precipitation climate research

Science.gov (United States)

Zolina, Olga; Simmer, Clemens; Kapala, Alice; Mächel, Hermann; Gulev, Sergey; Groisman, Pavel

2014-05-01

We present new high resolution precipitation daily grids developed at Meteorological Institute, University of Bonn and German Weather Service (DWD) under the STAMMEX project (Spatial and Temporal Scales and Mechanisms of Extreme Precipitation Events over Central Europe). Daily precipitation grids have been developed from the daily-observing precipitation network of DWD, which runs one of the World's densest rain gauge networks comprising more than 7500 stations. Several quality-controlled daily gridded products with homogenized sampling were developed covering the periods 1931-onwards (with 0.5 degree resolution), 1951-onwards (0.25 degree and 0.5 degree), and 1971-2000 (0.1 degree). Different methods were tested to select the best gridding methodology that minimizes errors of integral grid estimates over hilly terrain. Besides daily precipitation values with uncertainty estimates (which include standard estimates of the kriging uncertainty as well as error estimates derived by a bootstrapping algorithm), the STAMMEX data sets include a variety of statistics that characterize temporal and spatial dynamics of the precipitation distribution (quantiles, extremes, wet/dry spells, etc.). Comparisons with existing continental-scale daily precipitation grids (e.g., CRU, ECA E-OBS, GCOS) which include considerably less observations compared to those used in STAMMEX, demonstrate the added value of high-resolution grids for extreme rainfall analyses. These data exhibit spatial variability pattern and trends in precipitation extremes, which are missed or incorrectly reproduced over Central Europe from coarser resolution grids based on sparser networks. The STAMMEX dataset can be used for high-quality climate diagnostics of precipitation variability, as a reference for reanalyses and remotely-sensed precipitation products (including the upcoming Global Precipitation Mission products), and for input into regional climate and operational weather forecast models. We will present

Experimental study of diffuse auroral precipitations

International Nuclear Information System (INIS)

Mouaia, K.

1983-01-01

First chapter is devoted to low energy electron precipitation in the evening sector of the auroral magnetosphere, during quiet and disturbed magnetic periods. Four subjects are studied in detail: the latitude distribution of the varied auroral forms and their relations to external magnetosphere; the time coefficients related to precipitations, the form and the dynamic of the diffuse precipitation equatorial frontier; the precipitation effect on the ionosphere concentration. The last part of the chapter shows that the plasma convection in the magnetosphere, associated to wave-particle interactions near the equatorial accounts for the principal characteristics of the evening sector diffuse electronic precipitations. The second chapter deals with subauroral precipitations of low energy ions, after the magnetospheric substorms, in the high latitude regions of the morning sector [fr

Severe diabetic ketoacidosis and acute pericarditis precipitated by concomitant Graves′ thyrotoxicosis in type 1 diabetic patient

Directory of Open Access Journals (Sweden)

Muneera A Alshareef

2014-01-01

Full Text Available 20-year-old male known case of type 1 diabetes mellitus (T1DM presented to emergency department with vomiting and abdominal pain, and was diagnosed to have diabetic ketoacidosis (DKA. There was no obvious precipitating cause for DKA. Patient was started on DKA protocol and initially responded well to treatment. Later on, patient developed severe metabolic acidosis and chest pain. The cardiac evaluation established the diagnosis of acute pericarditis and ruled out acute coronary syndrome. The cause for his stormy coarse of DKA, and persistent tachycardia were further evaluated, and he was diagnosed to have concomitant thyrotoxicosis (graves′ disease complicating the DKA. He was successfully treated with aggressive management of DKA and started on thyrotoxicosis treatment. Autoimmune diseases are known to manifest in cluster but concomitant thyrotoxicosis precipitating DKA and causing acute pericarditis is rare. Prompt recognition of thyrotoxicosis in patients with persistent tachycardia, and treatment of thyrotoxicosis will improve outcome in DKA patients.

Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

Energy Technology Data Exchange (ETDEWEB)

Brown, A; Everitt, R A; Martin, C D; Davison, C C [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Labs.

1995-10-01

The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL`s Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics.

Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

International Nuclear Information System (INIS)

Brown, A.; Everitt, R.A.; Martin, C.D.; Davison, C.C.

1995-10-01

The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL's Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics

Evaluation of precipitates used in strainer head loss testing. Part I. Chemically generated precipitates

International Nuclear Information System (INIS)

Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

2009-01-01

The purpose of the current program was to evaluate the properties of chemical precipitates proposed by industry that have been used in sump strainer head loss testing. Specific precipitates that were evaluated included aluminum oxyhydroxide (AlOOH) and sodium aluminum silicate (SAS) prepared according to the procedures in WCAP-16530-NP, along with precipitates formed from injecting chemicals into the test loop according to the procedure used by one sump strainer test vendor for U.S. pressurized water reactors. The settling rates of the surrogate precipitates are strongly dependent on their particle size and are reasonably consistent with those expected from Stokes' Law or colloid aggregation models. Head loss tests showed that AlOOH and SAS surrogates are quite effective in increasing the head loss across a perforated pump inlet strainer that has an accumulated fibrous debris bed. The characteristics of aluminum hydroxide precipitate using sodium aluminate were dependent on whether it was formed in high-purity or ordinary tap water and whether excess silicate was present or not.

Continuous precipitation process of plutonium salts; Procede continu de precipitation des sels de plutonium

Energy Technology Data Exchange (ETDEWEB)

Richard, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-03-01

This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [French] Cette etude porte sur la precipitation continue de l'oxalate de plutonium. L'etude de la solubilite des differentes valences du plutonium dans des milieux acides nitrique-oxalique, puis nitrique-sulfurique-oxalique conduit a choisir la precipitation de l'oxalate de plutonium tetravalent. L'etude porte ensuite sur la sedimentation et la granulometrie de l'oxalate de Pu{sup 4+} obtenue en faisant varier differents parametres de la precipitation : la temperature, l'acidite, l'exces oxalique et le temps de murissement. La derniere partie traite des resultats obtenus avec plusieurs types d'appareils continus essayes au laboratoire. En conclusion sont donnees les conditions de marche de l'appareil tubulaire adopte, ainsi qu'une extrapolation a l'echelle industrielle sous forme d'un flow-sheet. (auteur)

Effective assimilation of global precipitation: simulation experiments

Directory of Open Access Journals (Sweden)

Guo-Yuan Lien

2013-07-01

Full Text Available Past attempts to assimilate precipitation by nudging or variational methods have succeeded in forcing the model precipitation to be close to the observed values. However, the model forecasts tend to lose their additional skill after a few forecast hours. In this study, a local ensemble transform Kalman filter (LETKF is used to effectively assimilate precipitation by allowing ensemble members with better precipitation to receive higher weights in the analysis. In addition, two other changes in the precipitation assimilation process are found to alleviate the problems related to the non-Gaussianity of the precipitation variable: (a transform the precipitation variable into a Gaussian distribution based on its climatological distribution (an approach that could also be used in the assimilation of other non-Gaussian observations and (b only assimilate precipitation at the location where at least some ensemble members have precipitation. Unlike many current approaches, both positive and zero rain observations are assimilated effectively. Observing system simulation experiments (OSSEs are conducted using the Simplified Parametrisations, primitivE-Equation DYnamics (SPEEDY model, a simplified but realistic general circulation model. When uniformly and globally distributed observations of precipitation are assimilated in addition to rawinsonde observations, both the analyses and the medium-range forecasts of all model variables, including precipitation, are significantly improved as compared to only assimilating rawinsonde observations. The effect of precipitation assimilation on the analyses is retained on the medium-range forecasts and is larger in the Southern Hemisphere (SH than that in the Northern Hemisphere (NH because the NH analyses are already made more accurate by the denser rawinsonde stations. These improvements are much reduced when only the moisture field is modified by the precipitation observations. Both the Gaussian transformation and

Encoding information into precipitation structures

International Nuclear Information System (INIS)

Martens, Kirsten; Bena, Ioana; Droz, Michel; Rácz, Zoltan

2008-01-01

Material design at submicron scales would be profoundly affected if the formation of precipitation patterns could be easily controlled. It would allow the direct building of bulk structures, in contrast to traditional techniques which consist of removing material in order to create patterns. Here, we discuss an extension of our recent proposal of using electrical currents to control precipitation bands which emerge in the wake of reaction fronts in A + + B – → C reaction–diffusion processes. Our main result, based on simulating the reaction–diffusion–precipitation equations, is that the dynamics of the charged agents can be guided by an appropriately designed time-dependent electric current so that, in addition to the control of the band spacing, the width of the precipitation bands can also be tuned. This makes straightforward the encoding of information into precipitation patterns and, as an amusing example, we demonstrate the feasibility by showing how to encode a musical rhythm

A test for Improvement of high resolution Quantitative Precipitation Estimation for localized heavy precipitation events

Science.gov (United States)

Lee, Jung-Hoon; Roh, Joon-Woo; Park, Jeong-Gyun

2017-04-01

Accurate estimation of precipitation is one of the most difficult and significant tasks in the area of weather diagnostic and forecasting. In the Korean Peninsula, heavy precipitations are caused by various physical mechanisms, which are affected by shortwave trough, quasi-stationary moisture convergence zone among varying air masses, and a direct/indirect effect of tropical cyclone. In addition to, various geographical and topographical elements make production of temporal and spatial distribution of precipitation is very complicated. Especially, localized heavy rainfall events in South Korea generally arise from mesoscale convective systems embedded in these synoptic scale disturbances. In weather radar data with high temporal and spatial resolution, accurate estimation of rain rate from radar reflectivity data is too difficult. Z-R relationship (Marshal and Palmer 1948) have adapted representatively. In addition to, several methods such as support vector machine (SVM), neural network, Fuzzy logic, Kriging were utilized in order to improve the accuracy of rain rate. These methods show the different quantitative precipitation estimation (QPE) and the performances of accuracy are different for heavy precipitation cases. In this study, in order to improve the accuracy of QPE for localized heavy precipitation, ensemble method for Z-R relationship and various techniques was tested. This QPE ensemble method was developed by a concept based on utilizing each advantage of precipitation calibration methods. The ensemble members were produced for a combination of different Z-R coefficient and calibration method.

Impact of Precipitation Fluctuation on Desert-Grassland ANPP

Directory of Open Access Journals (Sweden)

Liangxu Liu

2016-11-01

Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

Examine Precipitation Extremes in Terms of Storm Properties

Science.gov (United States)

Jiang, P.; Yu, Z.; Chen, L.; Gautam, M. R.; Acharya, K.

2017-12-01

The increasing potential of the extreme precipitation is of significant societal concern. Changes in precipitation extremes have been mostly examined using extreme precipitation indices or Intensity-Duration-Frequency (IDF) analyses, which often fail to reveal the characteristics of an integrated precipitation event. In this study, we will examine the precipitation extremes in terms of storm properties including storm duration, storm intensity, total storm precipitation, and within storm pattern. Single storm event will be identified and storm properties will be determined based on the hourly precipitation time series in the selected locations in southwest United States. Three types of extreme precipitation event will be recognized using the criteria as (1) longest storm duration; (2) Highest storm intensity; and (3) largest total precipitation over a storm. The trend and variation of extreme precipitation events will be discussed for each criterion. Based on the comparisons of the characteristics of extreme precipitation events identified using different criteria, we will provide guidelines for choosing proper criteria for extreme precipitation analysis in specific location.

Precipitation Climatology on Titan-like Exomoons.

Science.gov (United States)

Tokano, Tetsuya

2015-06-01

The availability of liquid water on the surface on Earth's continents in part relies on the precipitation of water. This implies that the habitability of exomoons has to consider not only the surface temperature and atmospheric pressure for the presence of liquid water, but also the global precipitation climatology. This study explores the sensitivity of the precipitation climatology of Titan-like exomoons to these moons' orbital configuration using a global climate model. The precipitation rate primarily depends on latitude and is sensitive to the planet's obliquity and the moon's rotation rate. On slowly rotating moons the precipitation shifts to higher latitudes as obliquity is increased, whereas on quickly rotating moons the latitudinal distribution does not strongly depend on obliquity. Stellar eclipse can cause a longitudinal variation in the mean surface temperature and surface pressure between the subplanetary and antiplanetary side if the planet's obliquity and the moon's orbital distance are small. In this particular condition the antiplanetary side generally receives more precipitation than the subplanetary side. However, precipitation on exomoons with dense atmospheres generally occurs at any longitude in contrast to tidally locked exoplanets.

Global Precipitation Measurement Poster

Science.gov (United States)

Azarbarzin, Art

2010-01-01

This poster presents an overview of the Global Precipitation Measurement (GPM) constellation of satellites which are designed to measure the Earth's precipitation. It includes the schedule of launches for the various satellites in the constellation, and the coverage of the constellation, It also reviews the mission capabilities, and the mission science objectives.

Hourly Precipitation Data (HPD) Publication

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Hourly Precipitation Data (HPD) Publication is archived and available from the National Climatic Data Center (NCDC). This publication contains hourly precipitation...

Precipitation variability increases in a warmer climate.

Science.gov (United States)

Pendergrass, Angeline G; Knutti, Reto; Lehner, Flavio; Deser, Clara; Sanderson, Benjamin M

2017-12-21

Understanding changes in precipitation variability is essential for a complete explanation of the hydrologic cycle's response to warming and its impacts. While changes in mean and extreme precipitation have been studied intensively, precipitation variability has received less attention, despite its theoretical and practical importance. Here, we show that precipitation variability in most climate models increases over a majority of global land area in response to warming (66% of land has a robust increase in variability of seasonal-mean precipitation). Comparing recent decades to RCP8.5 projections for the end of the 21 st century, we find that in the global, multi-model mean, precipitation variability increases 3-4% K -1 globally, 4-5% K -1 over land and 2-4% K -1 over ocean, and is remarkably robust on a range of timescales from daily to decadal. Precipitation variability increases by at least as much as mean precipitation and less than moisture and extreme precipitation for most models, regions, and timescales. We interpret this as being related to an increase in moisture which is partially mitigated by weakening circulation. We show that changes in observed daily variability in station data are consistent with increased variability.

CONCENTRATION OF Pu USING AN IODATE PRECIPITATE

Science.gov (United States)

Fries, B.A.

1960-02-23

A method is given for separating plutonium from lanthanum in a lanthanum fluoride carrier precipitation process for the recovery of plutonium values from an aqueous solution. The carrier precipitation process includes the steps of forming a lanthanum fluoride precipi- . tate, thereby carrying plutonium out of solution, metathesizing the fluoride precipitate to a hydroxide precipitate, and then dissolving the hydroxide precipitate in nitric acid. In accordance with the invention, the nitric acid solution, which contains plutonium and lanthanum, is made 0.05 to 0.15 molar in potassium iodate. thereby precipitating plutonium as plutonous iodate and the plutonous iodate is separated from the lanthanum- containing supernatant solution.

The effect of the precipitation of coherent and incoherent precipitates on the ductility and toughness of high-strength steel

International Nuclear Information System (INIS)

Hamano, R.

1993-01-01

The effect of the coexistence of coherent and incoherent precipitates, such as M 2 C and NiAl, on the ductility and plane strain fracture toughness of 5 wt pct Ni-2 wt pct Al-based high-strength steels was studied. In order to disperse coherent and incoherent precipitates, the heat treatments were carried out as follows: (a) austenitizing at 1373 K, (b) tempering at 1023 or 923 K for dispersing the incoherent precipitates of M 2 C and NiAl, and then (c) aging at 843 K for 2.4 ks to disperse the coherent precipitate of NiAl into the matrix, which contains incoherent precipitates, such as M 2 C and NiAl. The results were obtained as follows: (a) when the strengthening precipitates consist of coherent ones, such as M 2 C and/or NiAl, the ductility and toughness are extremely low, and (b) when the strengthening precipitates consist of coherent and incoherent precipitates, such as M 2 C and NiAl, the ductility and fracture toughness significantly increase with no loss in strength. It is shown that the coexistence of coherent and incoherent precipitates increases homogeneous deformation, thus preventing local strain concentration and early cleavage cracking. Accordingly, the actions of coherent precipitates in strengthening the matrix and of incoherent precipitates in promoting, homogeneous deformation can be expected to increase both the strength and toughness of the material

Object-Based Assessment of Satellite Precipitation Products

Directory of Open Access Journals (Sweden)

Jingjing Li

2016-06-01

Full Text Available An object-based verification approach is employed to assess the performance of the commonly used high-resolution satellite precipitation products: Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN, Climate Prediction center MORPHing technique (CMORPH, and Tropical Rainfall Measurement Mission (TRMM Multi-Satellite Precipitation Analysis (TMPA 3B42RT. The evaluation of the satellite precipitation products focuses on the skill of depicting the geometric features of the localized precipitation areas. Seasonal variability of the performances of these products against the ground observations is investigated through the examples of warm and cold seasons. It is found that PERSIANN is capable of depicting the orientation of the localized precipitation areas in both seasons. CMORPH has the ability to capture the sizes of the localized precipitation areas and performs the best in the overall assessment for both seasons. 3B42RT is capable of depicting the location of the precipitation areas for both seasons. In addition, all of the products perform better on capturing the sizes and centroids of precipitation areas in the warm season than in the cold season, while they perform better on depicting the intersection area and orientation in the cold season than in the warm season. These products are more skillful on correctly detecting the localized precipitation areas against the observations in the warm season than in the cold season.

Jejunal intussusception in a 10-year-old boy with blue rubber bleb nevus syndrome

Energy Technology Data Exchange (ETDEWEB)

Beluffi, Giampiero [Section of Paediatric Radiology, Department of Radiodiagnosis, IRCCS Policlinico S. Matteo, Piazzale Golgi, 2, 27100, Pavia PV (Italy); Romano, Piero; Matteotti, Chiara; Minniti, Silvio; Ceffa, Franco [Division of Paediatric Surgery, IRCCS Policlinico S. Matteo, Pavia (Italy); Morbini, Patrizia [Department of Pathology, IRCCS Policlinico S. Matteo, Pavia (Italy)

2004-09-01

Jejunal intussusception in a Chinese 10-year-old boy affected by the blue rubber bleb nevus syndrome is presented and discussed. The syndrome is rare, sporadically found with possible dominant inheritance, and due to a gene mutation mapped on the short arm of chromosome 9. It presents with distinctive cutaneous and gastrointestinal malformations together with possible other organ involvement. Gastrointestinal malformations tend to bleed and lead to anaemia. Infrequent complications of the gastrointestinal malformations are volvulus, intestinal infarction and intussusception. The age of the patient and the jejunal intussusception precipitated by a vascular malformation containing calcifications (which were also found in different gut segments) make this case remarkable. (orig.)

Jejunal intussusception in a 10-year-old boy with blue rubber bleb nevus syndrome

International Nuclear Information System (INIS)

Beluffi, Giampiero; Romano, Piero; Matteotti, Chiara; Minniti, Silvio; Ceffa, Franco; Morbini, Patrizia

2004-01-01

Jejunal intussusception in a Chinese 10-year-old boy affected by the blue rubber bleb nevus syndrome is presented and discussed. The syndrome is rare, sporadically found with possible dominant inheritance, and due to a gene mutation mapped on the short arm of chromosome 9. It presents with distinctive cutaneous and gastrointestinal malformations together with possible other organ involvement. Gastrointestinal malformations tend to bleed and lead to anaemia. Infrequent complications of the gastrointestinal malformations are volvulus, intestinal infarction and intussusception. The age of the patient and the jejunal intussusception precipitated by a vascular malformation containing calcifications (which were also found in different gut segments) make this case remarkable. (orig.)

A study of small-scale foliation in lengths of core enclosing fault zones in borehole WD-3, Permit Area D, Lac du Bonnet Batholith

Energy Technology Data Exchange (ETDEWEB)

Ejeckam, R. B.

1992-12-01

Small-scale foliation measurements in lengths of core from borehole WD-3 of Permit Area D of the Lac du Bonnet Batholith have defined five major mean orientation sets. They strike NW, N and NE. The orientations (strike to the left of the dip direction/dip) of these sets are as follows: Set I - 028/74 deg; II - 001/66 deg; III - 100/58 deg; IV - 076/83 deg; and V - 210/40 deg. The small-scale foliations were defined by different mineral types such as biotite crystals, plagioclase, mineral banding and quartz lenses. Well-developed biotite foliation is commonly present whenever well-developed plagioclase foliation exists, but as the strength of development weakens, the preferred orientations of plagioclase foliation do not correspond to those of biotite. It is also noted that the foliations appear to strike in directions orthogonal to the fractures in the fracture zones in the same depth interval. No significant change in foliation orientation was observed in Zones I to IV. Set V, however, whose mean orientation is 210/40 deg, is absent from the Zone IV interval, ranging from 872 to 905 m. (auth)

Variation of precipitation in Langtang Valley,Himalayas

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The variation of the δ 18O in precipitation and the relationship with precipitation amountat Kyangjin Base House and Yala Glacier Camp in Langtang Valley, Nepal Himalayas were ana-lyzed. The variations of the δ 18O with precipitation had great scatter, and the correlations betweenthe δ18O and precipitation changed with time on the synoptic scale. On the seasonal scale, therewas marked amount effect at Kyangjin Base House. However, the δ18O-precipitation gradient wassmaller than that on the synoptic scale. Because of the maintenance of the basic equilibrium be-tween stable isotopic compositions in atmospheric vapor and precipitation, the evaporation en-richment was light during the rainy season. Therefore, the variation of stable isotopic compositionsin precipitation was independent on the sampling intervals. Simulations show that the rainfall inLangtang Valley was not the outcome of the initial condensation of ocean vapor that originatedfrom low latitudes. The stable isotopic compositions in precipitation were greatly depleted due tothe strong rainout of the vapor from oceans as the vapor was raised over the Himalayas

Study of asphaltene precipitation by Calorimetry

DEFF Research Database (Denmark)

Verdier, Sylvain Charles Roland; Plantier, Frédéric; Bessières, David

2007-01-01

Can calorimetry bring new input to the Current understanding of asphaltene precipitation? In this work, two types of precipitation were studied by means of calorimetry: addition of n-heptane into asphaltene solutions and temperature/pressure variations on a recombined live oil. The first series...... of experiments showed that weak forces determine precipitation. Indeed, isothermal titration calorimetry could not detect any clear signal although this technique can detect low-energy transitions such as liquid-liquid equilibrium and rnicellization. The second series of tests proved that precipitation caused...... by T and P variations is exothermic for this system. Furthermore, the temperature-induced precipitation is accompanied by an increase in the apparent thermal expansivity. Therefore, it seems that these two phase transitions exhibit different calorimetric behaviours and they may not be as similar...

Formation of copper precipitates in silicon

Science.gov (United States)

Flink, Christoph; Feick, Henning; McHugo, Scott A.; Mohammed, Amna; Seifert, Winfried; Hieslmair, Henry; Heiser, Thomas; Istratov, Andrei A.; Weber, Eicke R.

1999-12-01

The formation of copper precipitates in silicon was studied after high-temperature intentional contamination of p- and n-type FZ and Cz-grown silicon and quench to room temperature. With the Transient Ion Drift (TID) technique on p-type silicon a critical Fermi level position at EC-0.2 eV was found. Only if the Fermi level position, which is determined by the concentrations of the acceptors and the copper donors, surpasses this critical value precipitation takes place. If the Fermi level is below this level the supersaturated interstitial copper diffuses out. An electrostatic precipitation model is introduced that correlates the observed precipitation behavior with the electrical activity of the copper precipitates as detected with Deep Level Transient Spectroscopy (DLTS) on n-type and with Minority Carrier Transient Spectroscopy (MCTS) on p-type silicon.

Precipitation of ammonium diuranate : a study

International Nuclear Information System (INIS)

Krishnamoorthy, T.S.; Mahadevan, N.; Sankar Das, M.

1991-01-01

The precipitation of ammonium diuranate (ADU) forms the first step in the production of UO 2 fuel for reactors, and hence the quality and consistency of the ADU precipitate is very important in industrial operations. An investigation, on the precipitation of ADU, was carried out under conditions similar to those in industrial production, to evaluate the effect of various variables on the consistency and the quality of ADU. The variables studied were concentration of uranium and ammonia, pH, temperature and form of ammonia (gas or solution). The properties studied were the settling rate of the precipitates, surface area of the ADUs and calcined oxides and compositional characteristics of the ADUs. Multifactorial experiments and ruggedness tests were applied to identify the parameters to which the precipitation process is most vulnerable, so that such parameters may be controlled effectively. Besides, the effect and the importance of equilibrium conditions during the precipitation process, on the quality of the final ADU, was also established. The paper presents the results of these studies. (author). 6 refs., 3 figs., 7 tabs

Estimating Tropical Cyclone Precipitation from Station Observations

Institute of Scientific and Technical Information of China (English)

REN Fumin; WANG Yongmei; WANG Xiaoling; LI Weijing

2007-01-01

In this paper, an objective technique for estimating the tropical cyclone (TC) precipitation from station observations is proposed. Based on a comparison between the Original Objective Method (OOM) and the Expert Subjective Method (ESM), the Objective Synoptic Analysis Technique (OSAT) for partitioning TC precipitation was developed by analyzing the western North Pacific (WNP) TC historical track and the daily precipitation datasets. Being an objective way of the ESM, OSAT overcomes the main problems in OOM,by changing two fixed parameters in OOM, the thresholds for the distance of the absolute TC precipitation (D0) and the TC size (D1), into variable parameters.Case verification for OSAT was also carried out by applying CMORPH (Climate Prediction Center MORPHing technique) daily precipitation measurements, which is NOAA's combined satellite precipitation measurement system. This indicates that OSAT is capable of distinguishing simultaneous TC precipitation rain-belts from those associated with different TCs or with middle-latitude weather systems.

CLIMATIC CHARACTERISTICS OF TYPHOON PRECIPITATION OVER CHINA

Institute of Scientific and Technical Information of China (English)

WANG Yong-mei; REN Fu-min; LI Wei-jing; WANG Xiao-ling

2008-01-01

The spatio-temporal characteristics of typhoon precipitation over China are analyzed in this study. The results show that typhoon precipitation covers most of central-eastern China. Typhoon precipitation gradually decreases from the southeastern coastal regions to the northwestern mainland. The maximum annual typhoon precipitation exceeds 700 mm in central-eastern Taiwan and part of Hainan, while the minimum annual typhoon precipitation occurs in parts of Inner Mongolia, Shanxi, Shaanxi and Sichuan, with values less than 10 mm. Generally, typhoons produce precipitation over China during April - December with a peak in August. The annual typhoon precipitation time series for observation stations are examined for long-term trends. The results show that decreasing trends exist in most of the stations from 1957 to 2004 and are statistically significant in parts of Taiwan, Hainan, coastal Southeast China and southern Northeast China. The anomaly of typhoon precipitation mainly results from that of the general circulation over Asia and the Walker Cell circulation over the equatorial central and eastern Pacific. Typhoon torrential rain is one of the extreme rainfall events in the southeastern coastal regions and parts of central mainland. In these regions, torrential rains are mostly caused by typhoons.

A global gridded dataset of daily precipitation going back to 1950, ideal for analysing precipitation extremes

Science.gov (United States)

Contractor, S.; Donat, M.; Alexander, L. V.

2017-12-01

Reliable observations of precipitation are necessary to determine past changes in precipitation and validate models, allowing for reliable future projections. Existing gauge based gridded datasets of daily precipitation and satellite based observations contain artefacts and have a short length of record, making them unsuitable to analyse precipitation extremes. The largest limiting factor for the gauge based datasets is a dense and reliable station network. Currently, there are two major data archives of global in situ daily rainfall data, first is Global Historical Station Network (GHCN-Daily) hosted by National Oceanic and Atmospheric Administration (NOAA) and the other by Global Precipitation Climatology Centre (GPCC) part of the Deutsche Wetterdienst (DWD). We combine the two data archives and use automated quality control techniques to create a reliable long term network of raw station data, which we then interpolate using block kriging to create a global gridded dataset of daily precipitation going back to 1950. We compare our interpolated dataset with existing global gridded data of daily precipitation: NOAA Climate Prediction Centre (CPC) Global V1.0 and GPCC Full Data Daily Version 1.0, as well as various regional datasets. We find that our raw station density is much higher than other datasets. To avoid artefacts due to station network variability, we provide multiple versions of our dataset based on various completeness criteria, as well as provide the standard deviation, kriging error and number of stations for each grid cell and timestep to encourage responsible use of our dataset. Despite our efforts to increase the raw data density, the in situ station network remains sparse in India after the 1960s and in Africa throughout the timespan of the dataset. Our dataset would allow for more reliable global analyses of rainfall including its extremes and pave the way for better global precipitation observations with lower and more transparent uncertainties.

Global precipitations and climate change. Proceedings

International Nuclear Information System (INIS)

Desbois, M.; Desalmand, F.

1994-01-01

The workshop reviewed the present status of knowledge concerning the past and present evolution of the distribution of precipitations at global scale, related to climate evolution at different time scales. This review was intended to assess the availability and quality of data which could help, through validation and initialization of model studies, to improve our understanding of the processes determining these precipitation changes. On another hand, the modelling specialists presented their actual use of precipitation data. Exchanges of views between the modelling and observing communities were thus made possible, leading to a set of recommendations for future studies. Sessions were then devoted to specific themes: 1) Paleoclimatology, 2) data collection, history and statistics, programmes, 3) methodologies and accuracy of large scale estimation of precipitation from conventional data, 4) estimation of precipitation from satellite data, 5) modelling studies. (orig.)

Prevalence of Metabolic Syndrome in Patients with HIV in the Era of Highly Active Antiretroviral Therapy.

Science.gov (United States)

Lombo, Bernardo; Alkhalil, Imran; Golden, Marjorie P; Fotjadhi, Irma; Ravi, Sreedhar; Virata, Michael; Lievano, Marta; Diez, Jose; Ghantous, Andre; Donohue, Thomas

2015-05-01

Since the introduction of combination antiretroviral therapy (cART) as the standard of care for HIV disease, there has been a precipitous decline in the death rate due to HIV/ AIDS. The purpose of this study was to report the prevalence of metabolic syndrome in HIV infected patients. Retrospective, cross-sectional, observational study of 259 patients with HIV infection treated with cART from an urban community hospital. Metabolic syndrome prevalence was defined using the International Diabetes Federation (IDF) and the U.S. National Cholesterol Education Program Adult Treatment Panel III (ATP III) criteria. Study patients were included regardless of the duration of cART. The prevalence of metabolic syndrome was 27% using IDF criteria and 26% using ATP III criteria. Logistic regression analysis found an association between treatment with the protease inhibitor darunavir and metabolic syndrome. (OR 3.32 with 95% confidence interval between 1.54 and 7.15). There is a high prevalence of metabolic syndrome and obesity in HIV patients treated with cART, especially those taking the protease inhibitor darunavir.

Precipitation Dynamical Downscaling Over the Great Plains

Science.gov (United States)

Hu, Xiao-Ming; Xue, Ming; McPherson, Renee A.; Martin, Elinor; Rosendahl, Derek H.; Qiao, Lei

2018-02-01

Detailed, regional climate projections, particularly for precipitation, are critical for many applications. Accurate precipitation downscaling in the United States Great Plains remains a great challenge for most Regional Climate Models, particularly for warm months. Most previous dynamic downscaling simulations significantly underestimate warm-season precipitation in the region. This study aims to achieve a better precipitation downscaling in the Great Plains with the Weather Research and Forecast (WRF) model. To this end, WRF simulations with different physics schemes and nudging strategies are first conducted for a representative warm season. Results show that different cumulus schemes lead to more pronounced difference in simulated precipitation than other tested physics schemes. Simply choosing different physics schemes is not enough to alleviate the dry bias over the southern Great Plains, which is related to an anticyclonic circulation anomaly over the central and western parts of continental U.S. in the simulations. Spectral nudging emerges as an effective solution for alleviating the precipitation bias. Spectral nudging ensures that large and synoptic-scale circulations are faithfully reproduced while still allowing WRF to develop small-scale dynamics, thus effectively suppressing the large-scale circulation anomaly in the downscaling. As a result, a better precipitation downscaling is achieved. With the carefully validated configurations, WRF downscaling is conducted for 1980-2015. The downscaling captures well the spatial distribution of monthly climatology precipitation and the monthly/yearly variability, showing improvement over at least two previously published precipitation downscaling studies. With the improved precipitation downscaling, a better hydrological simulation over the trans-state Oologah watershed is also achieved.

A Rare Case of Myxedema Coma with Neuroleptic Malignant Syndrome (NMS)

OpenAIRE

Dixit, Siddharth; Dutta, Manoj Kumar; Namdeo, Mayank

2015-01-01

Myxedema coma or hypothyroid crisis is an endocrine emergency and needs ICU management. Neuroleptic malignant syndrome (NMS) is another medical emergency which needs high degree of clinical suspicion else mortality can be high. There is a paradox in co existence of myxedema coma and NMS. While one is hypometabolic state another is hypermetabolic state and both can be precipitated by antipsychotics use. Hypothermia and flaccidity commonly expected in myxedema coma may mask fever and rigidity o...

Errors and Correction of Precipitation Measurements in China

Institute of Scientific and Technical Information of China (English)

REN Zhihua; LI Mingqin

2007-01-01

In order to discover the range of various errors in Chinese precipitation measurements and seek a correction method, 30 precipitation evaluation stations were set up countrywide before 1993. All the stations are reference stations in China. To seek a correction method for wind-induced error, a precipitation correction instrument called the "horizontal precipitation gauge" was devised beforehand. Field intercomparison observations regarding 29,000 precipitation events have been conducted using one pit gauge, two elevated operational gauges and one horizontal gauge at the above 30 stations. The range of precipitation measurement errors in China is obtained by analysis of intercomparison measurement results. The distribution of random errors and systematic errors in precipitation measurements are studied in this paper.A correction method, especially for wind-induced errors, is developed. The results prove that a correlation of power function exists between the precipitation amount caught by the horizontal gauge and the absolute difference of observations implemented by the operational gauge and pit gauge. The correlation coefficient is 0.99. For operational observations, precipitation correction can be carried out only by parallel observation with a horizontal precipitation gauge. The precipitation accuracy after correction approaches that of the pit gauge. The correction method developed is simple and feasible.

Precipitation of uranium concentrates by hydrogen peroxide

International Nuclear Information System (INIS)

Barbosa Filho, O.; Teixeira, L.A.C.

1987-01-01

An experimental study on the precipitation of uranyl peroxide (UO 4 x H 2 O) has been carried out in a laboratory scale. The objective was to assess the possibility of the peroxide route as an alternative to a conventional ammonium diuranate process. A factorial design was used to evaluate the effects of the initial pH, precipitation pH and H 2 O 2 /UO 2 2+ ratio upon the process. The responses were measured in terms of: efficiency of U precipitation, content of U in the precipitates, and distribution of impurities in the precipitates. (Author) [pt

Measurement of precipitation using lysimeters

Science.gov (United States)

Fank, Johann; Klammler, Gernot

2013-04-01

Austria's alpine foothill aquifers contain important drinking water resources, but are also used intensively for agricultural production. These groundwater bodies are generally recharged by infiltrating precipitation. A sustainable water resources management of these aquifers requires quantifying real evapotranspiration (ET), groundwater recharge (GR), precipitation (P) and soil water storage change (ΔS). While GR and ΔS can be directly measured by weighable lysimeters and P by separate precipitation gauges, ET is determined by solving the climatic water balance ET = P GR ± ΔS. According to WMO (2008) measurement of rainfall is strongly influenced by precipitation gauge errors. Most significant errors result from wind loss, wetting loss, evaporation loss, and due to in- and out-splashing of water. Measuring errors can be reduced by a larger area of the measuring gaugés surface and positioning the collecting vessel at ground level. Modern weighable lysimeters commonly have a surface of 1 m², are integrated into their typical surroundings of vegetation cover (to avoid oasis effects) and allow scaling the mass change of monolithic soil columns in high measuring accuracy (0.01 mm water equivalent) and high temporal resolution. Thus, also precipitation can be quantified by measuring the positive mass changes of the lysimeter. According to Meissner et al. (2007) also dew, fog and rime can be determined by means of highly precise weighable lysimeters. Furthermore, measuring precipitation using lysimeters avoid common measuring errors (WMO 2008) at point scale. Though, this method implicates external effects (background noise, influence of vegetation and wind) which affect the mass time series. While the background noise of the weighing is rather well known and can be filtered out of the mass time series, the influence of wind, which blows through the vegetation and affects measured lysimeter mass, cannot be corrected easily since there is no clear relation between

Comparing NEXRAD Operational Precipitation Estimates and Raingage Observations of Intense Precipitation in the Missouri River Basin.

Science.gov (United States)

Young, C. B.

2002-05-01

Accurate observation of precipitation is critical to the study and modeling of land surface hydrologic processes. NEXRAD radar-based precipitation estimates are increasingly used in field experiments, hydrologic modeling, and water and energy budget studies due to their high spatial and temporal resolution, national coverage, and perceived accuracy. Extensive development and testing of NEXRAD precipitation algorithms have been carried out in the Southern Plains. Previous studies (Young et al. 2000, Young et al. 1999, Smith et al. 1996) indicate that NEXRAD operational products tend to underestimate precipitation at light rain rates. This study investigates the performance of NEXRAD precipitation estimates of high-intensity rainfall, focusing on flood-producing storms in the Missouri River Basin. NEXRAD estimates for these storms are compared with data from multiple raingage networks, including NWS recording and non-recording gages and ALERT raingage data for the Kansas City metropolitan area. Analyses include comparisons of gage and radar data at a wide range of temporal and spatial scales. Particular attention is paid to the October 4th, 1998, storm that produced severe flooding in Kansas City. NOTE: The phrase `NEXRAD operational products' in this abstract includes precipitation estimates generated using the Stage III and P1 algorithms. Both of these products estimate hourly accumulations on the (approximately) 4 km HRAP grid.

Understanding dual precipitation strengthening in ultra-high strength low carbon steel containing nano-sized copper precipitates and carbides

Science.gov (United States)

Phaniraj, M. P.; Shin, Young-Min; Jung, Woo-Sang; Kim, Man-Ho; Choi, In-Suk

2017-07-01

Low carbon ferritic steel alloyed with Ti, Mo and Cu was hot rolled and interrupt cooled to produce nano-sized precipitates of copper and (Ti,Mo)C carbides. The steel had a tensile strength of 840 MPa, an increase in yield strength of 380 MPa over that of the plain carbon steel and reasonable ductility. Transmission electron microscopy and small angle neutron scattering were used to characterize size and volume fraction of the precipitates in the steels designed to form only copper precipitates and only (Ti,Mo)C carbides. The individual and combined precipitation strengthening contributions was calculated using the size and volume fraction of precipitates and compared with the measured values.

Global Precipitation Measurement (GPM) L-6

Science.gov (United States)

Neeck, Steven P.; Kakar, Ramesh K.; Azarbarzin, Ardeshir A.; Hou, Arthur Y.

2013-10-01

The Global Precipitation Measurement (GPM) mission will advance the measurement of global precipitation, making possible high spatial resolution precipitation measurements. GPM will provide the first opportunity to calibrate measurements of global precipitation across tropical, mid-latitude, and polar regions. The GPM mission has the following scientific objectives: (1) Advance precipitation measurement capability from space through combined use of active and passive remote-sensing techniques; (2) Advance understanding of global water/energy cycle variability and fresh water availability; (3) Improve climate prediction by providing the foundation for better understanding of surface water fluxes, soil moisture storage, cloud/precipitation microphysics and latent heat release in the Earth's atmosphere; (4) Advance Numerical Weather Prediction (NWP) skills through more accurate and frequent measurements of instantaneous rain rates; and (5) Improve high impact natural hazard (flood/drought, landslide, and hurricane hazard) prediction capabilities. The GPM mission centers on the deployment of a Core Observatory carrying an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. GPM, jointly led with the Japan Aerospace Exploration Agency (JAXA), involves a partnership with other international space agencies including the French Centre National d'Études Spatiales (CNES), the Indian Space Research Organisation (ISRO), the U.S. National Oceanic and Atmospheric Administration (NOAA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and others. The GPM Core Observatory is currently being prepared for shipment to Japan for launch. Launch is scheduled for February 2014 from JAXA's Tanegashima Space Center on an H-IIA 202 launch vehicle.

Improving precipitation estimates over the western United States using GOES-R precipitation data

Science.gov (United States)

Karbalaee, N.; Kirstetter, P. E.; Gourley, J. J.

2017-12-01

Satellite remote sensing data with fine spatial and temporal resolution are widely used for precipitation estimation for different applications such as hydrological modeling, storm prediction, and flash flood monitoring. The Geostationary Operational Environmental Satellites-R series (GOES-R) is the next generation of environmental satellites that provides hydrologic, atmospheric, and climatic information every 30 seconds over the western hemisphere. The high-resolution and low-latency of GOES-R observations is essential for the monitoring and prediction of floods, specifically in the Western United States where the vantage point of space can complement the degraded weather radar coverage of the NEXRAD network. The GOES-R rainfall rate algorithm will yield deterministic quantitative precipitation estimates (QPE). Accounting for inherent uncertainties will further advance the GOES-R QPEs since with quantifiable error bars, the rainfall estimates can be more readily fused with ground radar products. On the ground, the high-resolution NEXRAD-based precipitation estimation from the Multi-Radar/Multi-Sensor (MRMS) system, which is now operational in the National Weather Service (NWS), is challenged due to a lack of suitable coverage of operational weather radars over complex terrain. Distribution of QPE uncertainties associated with the GOES-R deterministic retrievals are derived and analyzed using MRMS over regions with good radar coverage. They will be merged with MRMS-based probabilistic QPEs developed to advance multisensor QPE integration. This research aims at improving precipitation estimation over the CONUS by combining the observations from GOES-R and MRMS to provide consistent, accurate and fine resolution precipitation rates with uncertainties over the CONUS.

A savanna response to precipitation intensity.

Directory of Open Access Journals (Sweden)

Ryan S Berry

Full Text Available As the atmosphere warms, precipitation events are becoming less frequent but more intense. A three-year experiment in Kruger National Park, South Africa, found that fewer, more intense precipitation events encouraged woody plant encroachment. To test whether or not these treatment responses persisted over time, here, we report results from all five years of that experiment. Grass growth, woody plant growth, total fine root number and area and hydrologic tracer uptake by grasses and woody plants were measured in six treated plots (8 m by 8 m and six control plots. Treatment effects on soil moisture were measured continuously in one treated and one control plot. During the fourth year, increased precipitation intensity treatments continued to decrease water flux in surface soils (0-10 cm, increase water flux in deeper soils (20+ cm, decrease grass growth and increase woody plant growth. Greater root numbers at 20-40 cm and greater woody plant uptake of a hydrological tracer from 45-60 cm suggested that woody plants increased growth by increasing root number and activity (but not root area in deeper soils. During the fifth year, natural precipitation events were large and intense so treatments had little effect on precipitation intensity or plant available water. Consistent with this effective treatment removal, there was no difference in grass or woody growth rates between control and treated plots, although woody plant biomass remained higher in treated than control plots due to treatment effects in the previous four years. Across the five years of this experiment, we found that 1 small increases in precipitation intensity can result in large increases in deep (20-130 cm soil water availability, 2 plant growth responses to precipitation intensity are rapid and disappear quickly, and 3 because woody plants accumulate biomass, occasional increases in precipitation intensity can result in long-term increases in woody plant biomass (i.e., shrub

Modelling the operation of precipitator with vortex effect

International Nuclear Information System (INIS)

Eysseric-Emile, C.

1994-01-01

In the Purex process which is implemented for the processing of irradiated fuels to eliminate fission products and to recover and valorise uranium and plutonium under the form of end products, a precipitation operation occurs to prepare the plutonium oxalate. This research thesis aims at analysing hydrodynamic characteristics of a specific apparatus used for this precipitation, the precipitator with vortex effect. In a first part, the author presents the problems associated with precipitation operations, their implementation in the processing of irradiated fuels, and compares the considered precipitator with other devices used for the precipitation of radioactive compounds. He proposes a review of literature on the vortex effect in agitated vessel, highlights the key parameter (the forced vortex radius), and reports some preliminary measurements performed on the precipitator. The author then reports the study of liquid phase flows in the precipitator, measurements of rate of suspension, and the study of micro-mixing with reactants. He finally reports attempts to validate trends noticed during flow analysis and a first simple modelling of the precipitator [fr

The Relationships Between Insoluble Precipitation Residues, Clouds, and Precipitation Over California's Southern Sierra Nevada During Winter Storms

Science.gov (United States)

Creamean, Jessie M.; White, Allen B.; Minnis, Patrick; Palikonda, Rabindra; Spangenberg, Douglas A.; Prather, Kimberly A.

2016-01-01

Ice formation in orographic mixed-phase clouds can enhance precipitation and depends on the type of aerosols that serve as ice nucleating particles (INP). The resulting precipitation from these clouds is a viable source of water, especially for regions such as the California Sierra Nevada. Thus, a better understanding of the sources of INP that impact orographic clouds is important for assessing water availability in California. This study presents a multi-site, multi-year analysis of single particle insoluble residues in precipitation samples that likely influenced cloud ice and precipitation formation above Yosemite National Park. Dust and biological particles represented the dominant fraction of the residues (64% on average). Cloud glaciation, determined using GOES satellite observations, not only depended on high cloud tops (greater than 6.2 km) and low temperatures (less than -26 C), but also on the composition of the dust and biological residues. The greatest prevalence of ice-phase clouds occurred in conjunction with biologically-rich residues and mineral dust rich in calcium, followed by iron and aluminosilicates. Dust and biological particles are known to be efficient INP, thus these residues are what likely influenced ice formation in clouds above the sites and subsequent precipitation quantities reaching the surface during events with similar meteorology. The goal of this study is to use precipitation chemistry information to gain a better understanding of the potential sources of INP in the south-central Sierra Nevada, where cloud-aerosol-precipitation interactions are under-studied and where mixed-phase orographic clouds represent a key element in the generation of precipitation and thus the water supply in California.

Recent and future extreme precipitation over Ukraine

Science.gov (United States)

Vyshkvarkova, Olena; Voskresenskaya, Elena

2014-05-01

The aim of study is to analyze the parameters of precipitation extremes and inequality over Ukraine in recent climate epoch and their possible changes in the future. Data of observations from 28 hydrometeorological stations over Ukraine and output of GFDL-CM3 model (CMIP5) for XXI century were used in the study. The methods of concentration index (J. Martin-Vide, 2004) for the study of precipitation inequality while the extreme precipitation indices recommended by the ETCCDI - for the frequency of events. Results. Precipitation inequality on the annual and seasonal scales was studied using estimated CI series for 1951-2005. It was found that annual CI ranges vary from 0.58 to 0.64. They increase southward from the north-west (forest zone) and the north-east (forest steppe zone) of Ukraine. CI maxima are located in the coastal regions of the Black Sea and the Sea of Azov. Annual CI spatial distribution indicates that the contribution of extreme precipitation into annual totals is most significant at the boundary zone between steppe and marine regions. At the same time precipitation pattern at the foothill of Carpathian Mountains is more homogenous. The CI minima (0.54) are typical for the winter season in foothill of Ukrainian Carpathians. The CI maxima reach 0.71 in spring at the steppe zone closed to the Black Sea coast. It should be noted that the greatest ranges of CI maximum and CI minimum deviation are typical for spring. It is associated with patterns of cyclone trajectories in that season. The most territory is characterized by tendency to decrease the contribution of extreme precipitation into the total amount (CI linear trends are predominantly negative in all seasons). Decadal and interdecadal variability of precipitation inequality associated with global processes in ocean-atmosphere system are also studied. It was shown that precipitation inequality over Ukraine on 10 - 15 % stronger in negative phase of Pacific Decadal Oscillation and in positive phase

Precipitation from Space: Advancing Earth System Science

Science.gov (United States)

Kucera, Paul A.; Ebert, Elizabeth E.; Turk, F. Joseph; Levizzani, Vicenzo; Kirschbaum, Dalia; Tapiador, Francisco J.; Loew, Alexander; Borsche, M.

2012-01-01

Of the three primary sources of spatially contiguous precipitation observations (surface networks, ground-based radar, and satellite-based radar/radiometers), only the last is a viable source over ocean and much of the Earth's land. As recently as 15 years ago, users needing quantitative detail of precipitation on anything under a monthly time scale relied upon products derived from geostationary satellite thermal infrared (IR) indices. The Special Sensor Microwave Imager (SSMI) passive microwave (PMW) imagers originated in 1987 and continue today with the SSMI sounder (SSMIS) sensor. The fortunate longevity of the joint National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) is providing the environmental science community a nearly unbroken data record (as of April 2012, over 14 years) of tropical and sub-tropical precipitation processes. TRMM was originally conceived in the mid-1980s as a climate mission with relatively modest goals, including monthly averaged precipitation. TRMM data were quickly exploited for model data assimilation and, beginning in 1999 with the availability of near real time data, for tropical cyclone warnings. To overcome the intermittently spaced revisit from these and other low Earth-orbiting satellites, many methods to merge PMW-based precipitation data and geostationary satellite observations have been developed, such as the TRMM Multisatellite Precipitation Product and the Climate Prediction Center (CPC) morphing method (CMORPH. The purpose of this article is not to provide a survey or assessment of these and other satellite-based precipitation datasets, which are well summarized in several recent articles. Rather, the intent is to demonstrate how the availability and continuity of satellite-based precipitation data records is transforming the ways that scientific and societal issues related to precipitation are addressed, in ways that would not be

Complex precipitation pathways in multicomponent alloys

Energy Technology Data Exchange (ETDEWEB)

Clouet, Emmanuel; Nastar, Maylise [Service de Recherches de Metallurgie Physique, CEA/Saclay, 91191 Gif-sur-Yvette (France); Lae, Ludovic; Deschamps, Alexis [LTPCM/ENSEEG, UMR CNRS 5614, Domaine Universitaire, BP 75, 38402 St Martin d' Heres (France); Epicier, Thierry [Groupe d' Etudes de Metallurgie Physique et de Physique des Materiaux, UMR CNRS 5510, INSA, 69621 Villeurbanne (France); Lefebvre, Williams [Groupe de Physique des Materiaux, UMR CNRS 6634, Universite de Rouen, 76801 Saint Etienne du Rouvray (France)

2006-07-01

One usual way to strengthen a metal is to add alloying elements and to control the size and the density of the precipitates obtained. However, precipitation in multicomponent alloys can take complex pathways depending on the relative diffusivity of solute atoms and on the relative driving forces involved. In Al - Zr - Sc alloys, atomic simulations based on first-principle calculations combined with various complementary experimental approaches working at different scales reveal a strongly inhomogeneous structure of the precipitates: owing to the much faster diffusivity of Sc compared with Zr in the solid solution, and to the absence of Zr and Sc diffusion inside the precipitates, the precipitate core is mostly Sc-rich, whereas the external shell is Zr-rich. This explains previous observations of an enhanced nucleation rate in Al - Zr - Sc alloys compared with binary Al - Sc alloys, along with much higher resistance to Ostwald ripening, two features of the utmost importance in the field of light high-strength materials. (authors)

Precipitate strengthening of nanostructured aluminium alloy.

Science.gov (United States)

Wawer, Kinga; Lewandowska, Malgorzata; Kurzydlowski, Krzysztof J

2012-11-01

Grain boundaries and precipitates are the major microstructural features influencing the mechanical properties of metals and alloys. Refinement of the grain size to the nanometre scale brings about a significant increase in the mechanical strength of the materials because of the increased number of grain boundaries which act as obstacles to sliding dislocations. A similar effect is obtained if nanoscale precipitates are uniformly distributed in coarse grained matrix. The development of nanograin sized alloys raises the important question of whether or not these two mechanisms are "additive" and precipitate strengthening is effective in nanostructured materials. In the reported work, hydrostatic extrusion (HE) was used to obtain nanostructured 7475 aluminium alloy. Nanosized precipitates were obtained by post-HE annealing. It was found that such annealing at the low temperatures (100 degrees C) results in a significant increase in the microhardness (HV0.2) and strength of the nanostructured 7475 aluminium alloy. These results are discussed in terms of the interplay between the precipitation and deformation of nanocrystalline metals.

IDF-curves for precipitation In Belgium

International Nuclear Information System (INIS)

Mohymont, Bernard; Demarde, Gaston R.

2004-01-01

The Intensity-Duration-Frequency (IDF) curves for precipitation constitute a relationship between the intensity, the duration and the frequency of rainfall amounts. The intensity of precipitation is expressed in mm/h, the duration or aggregation time is the length of the interval considered while the frequency stands for the probability of occurrence of the event. IDF-curves constitute a classical and useful tool that is primarily used to dimension hydraulic structures in general, as e.g., sewer systems and which are consequently used to assess the risk of inundation. In this presentation, the IDF relation for precipitation is studied for different locations in Belgium. These locations correspond to two long-term, high-quality precipitation networks of the RMIB: (a) the daily precipitation depths of the climatological network (more than 200 stations, 1951-2001 baseline period); (b) the high-frequency 10-minutes precipitation depths of the hydro meteorological network (more than 30 stations, 15 to 33 years baseline period). For the station of Uccle, an uninterrupted time-series of more than one hundred years of 10-minutes rainfall data is available. The proposed technique for assessing the curves is based on maximum annual values of precipitation. A new analytical formula for the IDF-curves was developed such that these curves stay valid for aggregation times ranging from 10 minutes to 30 days (when fitted with appropriate data). Moreover, all parameters of this formula have physical dimensions. Finally, adequate spatial interpolation techniques are used to provide nationwide extreme values precipitation depths for short- to long-term durations With a given return period. These values are estimated on the grid points of the Belgian ALADIN-domain used in the operational weather forecasts at the RMIB.(Author)

Precipitates and boundaries interaction in ferritic ODS steels

Energy Technology Data Exchange (ETDEWEB)

Sallez, Nicolas, E-mail: nicolas.sallez@simap.grenoble-inp.fr [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France); Hatzoglou, Constantinos [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Delabrouille, Fredéric [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Sornin, Denis; Chaffron, Laurent [CEA, DEN, Service de Recherches Métallurgiques Appliqué, 91191 Gif-sur-Yvette (France); Blat-Yrieix, Martine [EDF–EDF R& D, Les Renardières, 77818 Moret-sur-Loing (France); Radiguet, Bertrand; Pareige, Philippe [Groupe de Physique des Matériaux, Université et INSA de Rouen, UMR CNRS 6634, Normandie Université (France); Donnadieu, Patricia; Bréchet, Yves [Univ. Grenoble Alpes, SIMAP, F-38000 Grenoble (France)

2016-04-15

In the course of a recrystallization study of Oxide Dispersion Strengthened (ODS) ferritic steels during extrusion, particular interest was paid to the (GB) Grain Boundaries interaction with precipitates. Complementary and corresponding characterization experiments using Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and Atom Probe Tomography (APT) have been carried out on a voluntarily interrupted extrusion or extruded samples. Microscopic observations of Precipitate Free Zones (PFZ) and precipitates alignments suggest precipitate interaction with migrating GB involving dissolution and Oswald ripening of the precipitates. This is consistent with the local chemical information gathered by EDX and APT. This original mechanism for ODS steels is similar to what had been proposed in the late 80s for similar observation made on Ti alloys reinforced by nanosized yttrium oxides: An interaction mechanism between grain boundaries and precipitates involving a diffusion controlled process of precipitates dissolution at grain boundaries. It is believed that this mechanism can be of primary importance to explain the mechanical behaviour of such steels. - Highlights: • To study the microstructural evolution of a ferritic ODS steel during its extrusion, observations have been carried on samples resulting from a voluntarily interrupted extrusion and extruded materials. • A highly heterogeneous precipitate population have been observed. Nanosized coherent precipitates (2–5 nm) on both sides of the grain boundaries despite grain boundary migration after precipitation due to further thermo-mechanical processing as well as coarse precipitates (10–40 nm) alignments are observed on the grain boundaries and within the grains, parallel to the grain boundaries. • Asymmetrical PFZs can be observed around precipitates alignments and grain boundaries. Using TEM with EDX and APT we have been able to ensure that the PFZs are chemically depleted. �

Stable Isotopic Variations in Precipitation in Southwest China

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

This study analyzes the relationships of stable isotopes in precipitation with temperature, air pressure and humidity at different altitudes, and the potential influencing mechanisms of control factors on the stable isotopes in precipitation in Southwest China. There appear marked negative correlations of the δ18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW)at the Mengzi, Simao and Tengchong stations on the synoptic timescale; the marked negative correlations between the δ18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850hPa are different from the temperature effect in middle-high-latitude inland areas. In addition, the notable positive correlation between the δ18O in precipitation and the dew-point deficit △Td at different altitudes is found at the three stations. Precipitation is not the only factor generating an amount effect. Probably,the amount effect is related to the variations of atmospheric circulation and vapor origins. On the annual timescale, the annual precipitation amount weighted-mean δ18O displays negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with an abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in Southwest China and generates abnormally strong rainfall on the way. Meanwhile, the abnormally strong condensation process will release more condensed latent heat in the atmosphere, and this will lead to a rise of atmospheric temperature during rainfall but a decline of δ18O in the precipitation. On the other hand, in the years with an abnormally weak summer monsoon, the precipitation and the atmospheric temperature during rainfalls decrease abnormally but the δ18O in precipitation increases.

Satellite precipitation estimation over the Tibetan Plateau

Science.gov (United States)

Porcu, F.; Gjoka, U.

2012-04-01

Precipitation characteristics over the Tibetan Plateau are very little known, given the scarcity of reliable and widely distributed ground observation, thus the satellite approach is a valuable choice for large scale precipitation analysis and hydrological cycle studies. However,the satellite perspective undergoes various shortcomings at the different wavelengths used in atmospheric remote sensing. In the microwave spectrum often the high soil emissivity masks or hides the atmospheric signal upwelling from light-moderate precipitation layers, while low and relatively thin precipitating clouds are not well detected in the visible-infrared, because of their low contrast with cold and bright (if snow covered) background. In this work an IR-based, statistical rainfall estimation technique is trained and applied over the Tibetan Plateau hydrological basin to retrive precipitation intensity at different spatial and temporal scales. The technique is based on a simple artificial neural network scheme trained with two supervised training sets assembled for monsoon season and for the rest of the year. For the monsoon season (estimated from June to September), the ground radar precipitation data for few case studies are used to build the training set: four days in summer 2009 are considered. For the rest of the year, CloudSat-CPR derived snowfall rate has been used as reference precipitation data, following the Kulie and Bennartz (2009) algorithm. METEOSAT-7 infrared channels radiance (at 6.7 and 11 micometers) and derived local variability features (such as local standard deviation and local average) are used as input and the actual rainrate is obtained as output for each satellite slot, every 30 minutes on the satellite grid. The satellite rainrate maps for three years (2008-2010) are computed and compared with available global precipitation products (such as C-MORPH and TMPA products) and with other techniques applied to the Plateau area: similarities and differences are

Measurement of γ'precipitates in nimonic PE16

International Nuclear Information System (INIS)

Baker, C.; Lobb, R.C.

1977-09-01

γ' precipitates in Nimonic PE16 have been examined using bright and dark field imaging techniques in an electron microscope. The validity of these techniques to determine mean precipitate diameters, precipitate density and volume fraction is discussed. It is concluded that bright field imaging techniques are sufficiently accurate to measure γ' precipitate diameters but it is essential to use dark field imaging techniques to determine γ' precipitate density or volume fraction. (author)

Aluminum precipitation from Hanford DSSF

International Nuclear Information System (INIS)

Borgen, D.; Frazier, P.; Staton, G.

1994-01-01

A series of pilot scale tests using simulated Double Shell Slurry Feed (DSSF) showed that well-settled aluminum precipitate can be produced in Hanford double shell tank (DST) high level waste by slow neutralization with carbon dioxide. This pretreatment could provide an early grout feed and free tank space, as well as facilitate downstream processes such as ion exchange by providing a less caustic feed. A total of eight test runs were completed using a 10-ft tall 3-in i.d. glass column. The 10-ft height corresponds to about one third of the vertical height of a DST, hence providing a reasonable basis for extrapolating the observed precipitate settling and compaction to the actual waste tank environment. Four runs (three with a simplified simulant and one with a chemically complete simulant) produced well settled precipitates averaging 1.5 to 2 feet high. Aluminum gel rather than settled precipitate resulted from one test where neutralization was too rapid

Rheology of tetraphenylborate precipitate slurry

International Nuclear Information System (INIS)

Goren, I.D.; Martin, H.D.; McLain, M.A.

1985-01-01

The rheological properties of tetraphenylborate precipitate slurry were determined. This nonradioactive slurry simulates the radioactive tetraphenylborate precipitate generated at the Savannah River Plant by the In-Tank Precipitation Process. The data obtained in this study was applied in the design of slurry pumps, transfer pumps, transfer lines, and vessel agitation for the Defense Waste Processing Facility and other High Level Waste treatment projects. The precipitate slurry behaves as a Bingham plastic. The yield stress is directly proportional to the concentration of insoluble solids over the range of concentrations studied. The consistency is also a linear function of insoluble solids over the same concentration range. Neither the yield stress nor the consistency was observed to be affected by the presence of the soluble solids. Temperature effects on flow properties of the slurry were also examined: the yield stress is inversely proportional to temperature, but the consistency of the slurry is independent of temperature. No significant time-dependent effects were found. 4 refs., 4 figs., 3 tabs

IMPROVED PROCESS OF PLUTONIUM CARRIER PRECIPITATION

Science.gov (United States)

Faris, B.F.

1959-06-30

This patent relates to an improvement in the bismuth phosphate process for separating and recovering plutonium from neutron irradiated uranium, resulting in improved decontamination even without the use of scavenging precipitates in the by-product precipitation step and subsequently more complete recovery of the plutonium in the product precipitation step. This improvement is achieved by addition of fluomolybdic acid, or a water soluble fluomolybdate, such as the ammonium, sodium, or potassium salt thereof, to the aqueous nitric acid solution containing tetravalent plutonium ions and contaminating fission products, so as to establish a fluomolybdate ion concentration of about 0.05 M. The solution is then treated to form the bismuth phosphate plutonium carrying precipitate.

Nutrition in clinical practice-the refeeding syndrome: illustrative cases and guidelines for prevention and treatment.

Science.gov (United States)

Stanga, Z; Brunner, A; Leuenberger, M; Grimble, R F; Shenkin, A; Allison, S P; Lobo, D N

2008-06-01

The refeeding syndrome is a potentially lethal complication of refeeding in patients who are severely malnourished from whatever cause. Too rapid refeeding, particularly with carbohydrate may precipitate a number of metabolic and pathophysiological complications, which may adversely affect the cardiac, respiratory, haematological, hepatic and neuromuscular systems leading to clinical complications and even death. We aimed to review the development of the refeeding syndrome in a variety of situations and, from this and the literature, devise guidelines to prevent and treat the condition. We report seven cases illustrating different aspects of the refeeding syndrome and the measures used to treat it. The specific complications encountered, their physiological mechanisms, identification of patients at risk, and prevention and treatment are discussed. Each case developed one or more of the features of the refeeding syndrome including deficiencies and low plasma levels of potassium, phosphate, magnesium and thiamine combined with salt and water retention. These responded to specific interventions. In most cases, these abnormalities could have been anticipated and prevented. The main features of the refeeding syndrome are described with a protocol to anticipate, prevent and treat the condition in adults.

Research of chemical structure of atmospheric precipitation

International Nuclear Information System (INIS)

Korenyak, D.

2001-01-01

The structure of atmospheric precipitation changes in its passing through the air medium. Thus, the atmospheric precipitation is one of the ecological factors, acting regularly. The research of chemical structure of atmospheric precipitation is closely connected with the problems of turnover of elements, with sanitary - ecological conditions of regions, with the matters of agricultural equipment and of salt balance of the soils. In paper the author for the first time represents the data on chemical structure of precipitation in the town. The data of chemical analysis of 18 samples are given. Obtained results permitted, to a certain extent, to determine the mechanisms of formation of atmospheric precipitation in the region investigated and its genesis. (authors)

Precipitation of uranium concentrates by hydrogen peroxide

International Nuclear Information System (INIS)

Barbosa Filho, O.

1986-12-01

An experimental study on the (UO 4 .xH 2 ) uranyl peroxide precipitation from a uranium process strip solution is presented. The runs were performed in a batch reactor, in laboratory scale. The main objective was to assess the possibility of the peroxide route as an alternative to a conventional ammonium diuranate process. The chemical composition of process solution was obtained. The experiments were conducted according to a factorial design, aiming to evaluate the effects of initial pH, precipitation pH and H 2 O 2 /UO 2 2+ ratio upon the process. The responses were measured in terms of the efficiency of U precipitation, the content of U in the precipitates and the distribution of impurities in the precipitates. The results indicated that the process works is satisfactory on the studied conditions and depending on conditions, it is possible to achieve levels of U precipitation efficiency greater than 99.9% in reaction times of 2 hours. The precipitates reach grades around 99% U 3 O 8 after calcination (900 0 C) and impurities fall below the limit for penalties established by the ASTM and the Allied Chemical Standards. The precipitates are composed of large aggregates of crystals of 1-4 μm, are fast settling and filtering, and are free-flowing when dry. (Author) [pt

Scaling and clustering effects of extreme precipitation distributions

Science.gov (United States)

Zhang, Qiang; Zhou, Yu; Singh, Vijay P.; Li, Jianfeng

2012-08-01

SummaryOne of the impacts of climate change and human activities on the hydrological cycle is the change in the precipitation structure. Closely related to the precipitation structure are two characteristics: the volume (m) of wet periods (WPs) and the time interval between WPs or waiting time (t). Using daily precipitation data for a period of 1960-2005 from 590 rain gauge stations in China, these two characteristics are analyzed, involving scaling and clustering of precipitation episodes. Our findings indicate that m and t follow similar probability distribution curves, implying that precipitation processes are controlled by similar underlying thermo-dynamics. Analysis of conditional probability distributions shows a significant dependence of m and t on their previous values of similar volumes, and the dependence tends to be stronger when m is larger or t is longer. It indicates that a higher probability can be expected when high-intensity precipitation is followed by precipitation episodes with similar precipitation intensity and longer waiting time between WPs is followed by the waiting time of similar duration. This result indicates the clustering of extreme precipitation episodes and severe droughts or floods are apt to occur in groups.

A multi-source precipitation approach to fill gaps over a radar precipitation field

Science.gov (United States)

Tesfagiorgis, K. B.; Mahani, S. E.; Khanbilvardi, R.

2012-12-01

Satellite Precipitation Estimates (SPEs) may be the only available source of information for operational hydrologic and flash flood prediction due to spatial limitations of radar and gauge products. The present work develops an approach to seamlessly blend satellite, radar, climatological and gauge precipitation products to fill gaps over ground-based radar precipitation fields. To mix different precipitation products, the bias of any of the products relative to each other should be removed. For bias correction, the study used an ensemble-based method which aims to estimate spatially varying multiplicative biases in SPEs using a radar rainfall product. Bias factors were calculated for a randomly selected sample of rainy pixels in the study area. Spatial fields of estimated bias were generated taking into account spatial variation and random errors in the sampled values. A weighted Successive Correction Method (SCM) is proposed to make the merging between error corrected satellite and radar rainfall estimates. In addition to SCM, we use a Bayesian spatial method for merging the gap free radar with rain gauges, climatological rainfall sources and SPEs. We demonstrate the method using SPE Hydro-Estimator (HE), radar- based Stage-II, a climatological product PRISM and rain gauge dataset for several rain events from 2006 to 2008 over three different geographical locations of the United States. Results show that: the SCM method in combination with the Bayesian spatial model produced a precipitation product in good agreement with independent measurements. The study implies that using the available radar pixels surrounding the gap area, rain gauge, PRISM and satellite products, a radar like product is achievable over radar gap areas that benefits the scientific community.

Wernicke-Korsakoff syndrome not related to alcohol use: a systematic review.

Science.gov (United States)

Scalzo, Simon J; Bowden, Stephen C; Ambrose, Margaret L; Whelan, Greg; Cook, Mark J

2015-12-01

Although Wernicke-Korsakoff syndrome (WKS) is a common condition, diagnosis remains difficult. WKS not associated with alcohol is rare and thought to present differently to alcohol-related WKS. We conducted a systematic review of WKS not related to alcohol to enhance understanding of WKS not related to alcohol and WKS in general. A systematic review was conducted of case reports, published in English, of Wernicke's encephalopathy and WKS in patients without a history of alcohol-use disorder. Main data sources: MEDLINE, Index Medicus. Eligible cases totaled 623. Publication dates ranged from 1867 to 2014. Comparisons of clinical presentation were made with published data on samples comprising, almost exclusively, alcohol-related WKS. A wide array of illnesses precipitated WKS. When diagnosis of WKS was performed postmortem, non-alcohol-related cases presented a similar number of signs of the classic triad as alcohol-related cases (p=0.662, Cohen's w=0.12) but more signs when diagnosed antemortem (pKorsakoff syndrome or ongoing memory impairment was reported in 25% of non-alcohol-related WKS, although cognitive status was not explicitly reported in many cases. When duration of memory impairment was reported, 56% had clinically obvious memory impairment lasting beyond the period of acute presentation. Non-alcohol-related WKS was more often associated with female gender, younger age, shorter duration of precipitating illness and better survival rate compared to alcohol-related WKS. Thiamine deficiency in the absence of an alcohol-use disorder can cause the full clinical spectrum of WKS, including chronic cognitive impairment and Korsakoff syndrome. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Evaluation of precipitates used in strainer head loss testing: Part III. Long-term aluminum hydroxide precipitation tests in borated water

International Nuclear Information System (INIS)

Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

2011-01-01

Research highlights: → Aluminum hydroxide precipitation boundary is similar to that for amorphous phase. → Various precipitation tests are combined into one map in temperature-'pH + p[Al] T '. → Flocculation tendency of precipitates depend on pH and total Al concentration. → DLVO theory explains qualitatively the dependency of flocculation tendency on pH. - Abstract: Long-term aluminum (Al) hydroxide precipitation tests were conducted in slightly alkaline solutions containing 2500 ppm boron. The solution temperature was cycled to obtain a temperature history more representative of emergency core cooling system temperatures after a loss-of-coolant accident. The observed Al precipitation boundary was close to predicted results for amorphous precipitates, which are higher than the solubility expected for crystalline forms. Bench-scale and loop head loss test results under various conditions were successfully combined into single map in a temperature - 'pH + p[Al] T ' domain, which yielded two bounding lines for Al hydroxide solubility in borated alkaline water that depend on whether or not loop head loss tests with Al alloy coupons are included. Precipitates were observed to form either as fine, cloudy suspensions, which showed very little tendency to settle, or as flocculated precipitates. The flocculation tendency of the precipitates can be qualitatively explained by a colloid stability theory or a phase diagram for protein solutions.

Precipitation Kinetics in a Nb-stabilized Ferritic Stainless Steel

Science.gov (United States)

Labonne, M.; Graux, A.; Cazottes, S.; Danoix, F.; Cuvilly, F.; Chassagne, F.; Perez, M.; Massardier, V.

2017-08-01

The precipitation occurring in a Nb-stabilized ferritic stainless steel, containing initially Nb(C, N) carbonitrides and Fe3Nb3X precipitates, was investigated during aging treatments performed between 923 K and 1163 K (650 °C and 890 °C) by combining different techniques, (thermoelectric power (TEP), scanning/transmission electron microscopy (SEM/TEM), and atom probe tomography (APT)), in order to determine the precipitation kinetics, the nature and morphology of the newly formed precipitates as well as the chemistry of the initial Fe3Nb3X precipitates, where X stands for C or N. The following composition was proposed for these precipitates: (Fe0.81 Cr0.19)3 (Nb0.85 Si0.08 Mo0.07)3 (N0.8 C0.2), highlighting the simultaneous presence of N and C in the precipitates. With regard to the precipitation in the investigated temperature range, two main phenomena, associated with a hardness decrease, were clearly identified: (i) the precipitation of Fe2Nb precipitates from the niobium initially present in solution or coming from the progressive dissolution of the Fe3Nb3X precipitates and (ii) the precipitation of the χ-phase at grain boundaries for longer aging times. From the TEP kinetics, a time-temperature-precipitation diagram has been proposed.

Precipitation variability assessment of northeast China: Songhua ...

Indian Academy of Sciences (India)

Variability in precipitation is critical for the management of water resources. ... applied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainy ... 2015). As a result, such irregularities in precipitation,. i.e., droughts and floods can affect the ... (January–December), years and decades.

Final fate of spherically symmetric gravitational collapse of a dust cloud in Einstein-Gauss-Bonnet gravity

International Nuclear Information System (INIS)

Maeda, Hideki

2006-01-01

We give a model of the higher-dimensional spherically symmetric gravitational collapse of a dust cloud including the perturbative effects of quantum gravity. The n(≥5)-dimensional action with the Gauss-Bonnet term for gravity is considered and a simple formulation of the basic equations is given for the spacetime M≅M 2 xK n-2 with a perfect fluid and a cosmological constant. This is a generalization of the Misner-Sharp formalism of the four-dimensional spherically symmetric spacetime with a perfect fluid in general relativity. The whole picture and the final fate of the gravitational collapse of a dust cloud differ greatly between the cases with n=5 and n≥6. There are two families of solutions, which we call plus-branch and the minus-branch solutions. A plus-branch solution can be attached to the outside vacuum region which is asymptotically anti-de Sitter in spite of the absence of a cosmological constant. Bounce inevitably occurs in the plus-branch solution for n≥6, and consequently singularities cannot be formed. Since there is no trapped surface in the plus-branch solution, the singularity formed in the case of n=5 must be naked. On the other hand, a minus-branch solution can be attached to the outside asymptotically flat vacuum region. We show that naked singularities are massless for n≥6, while massive naked singularities are possible for n=5. In the homogeneous collapse represented by the flat Friedmann-Robertson-Walker solution, the singularity formed is spacelike for n≥6, while it is ingoing-null for n=5. In the inhomogeneous collapse with smooth initial data, the strong cosmic censorship hypothesis holds for n≥10 and for n=9 depending on the parameters in the initial data, while a naked singularity is always formed for 5≤n≤8. These naked singularities can be globally naked when the initial surface radius of the dust cloud is fine-tuned, and then the weak cosmic censorship hypothesis is violated

Precipitation alters interactions in a grassland ecological community.

Science.gov (United States)

Deguines, Nicolas; Brashares, Justin S; Prugh, Laura R

2017-03-01

Climate change is transforming precipitation regimes world-wide. Changes in precipitation regimes are known to have powerful effects on plant productivity, but the consequences of these shifts for the dynamics of ecological communities are poorly understood. This knowledge gap hinders our ability to anticipate and mitigate the impacts of climate change on biodiversity. Precipitation may affect fauna through direct effects on physiology, behaviour or demography, through plant-mediated indirect effects, or by modifying interactions among species. In this paper, we examined the response of a semi-arid ecological community to a fivefold change in precipitation over 7 years. We examined the effects of precipitation on the dynamics of a grassland ecosystem in central California from 2007 to 2013. We conducted vegetation surveys, pitfall trapping of invertebrates, visual surveys of lizards and capture-mark-recapture surveys of rodents on 30 plots each year. We used structural equation modelling to evaluate the direct, indirect and modifying effects of precipitation on plants, ants, beetles, orthopterans, kangaroo rats, ground squirrels and lizards. We found pervasive effects of precipitation on the ecological community. Although precipitation increased plant biomass, direct effects on fauna were often stronger than plant-mediated effects. In addition, precipitation altered the sign or strength of consumer-resource and facilitative interactions among the faunal community such that negative or neutral interactions became positive or vice versa with increasing precipitation. These findings indicate that precipitation influences ecological communities in multiple ways beyond its recognized effects on primary productivity. Stochastic variation in precipitation may weaken the average strength of biotic interactions over time, thereby increasing ecosystem stability and resilience to climate change. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological

Precipitation behaviors of X70 acicular ferrite pipeline steel

Institute of Scientific and Technical Information of China (English)

Hao Yu; Yi Sun; Qixiang Chen; Haitao Jiang; Lihong Zhang

2006-01-01

The morphology, structure, and chemical composition of precipitates in the final microstructure of Nb-V-Ti microalloyed X70 acicular ferrite pipeline steel were investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Precipitates observed by TEM can be classified into two groups. The large precipitates are complex compounds that comprise square-shaped TiN precipitate as core with fine Nb-containing precipitate nucleated on pre-existing TiN precipitate as caps on one or more faces at high temperature. In contrast, the fine and spherical Nb carbides and/or carbonitrides precipitate heterogeneously on dislocations and sub-boundaries at low temperature. From the analysis in terms of thermodynamics, EDS and chemical composition of the steel, NbC precipitation is considered to be the predominant precipitation behavior in the tested steel under the processing conditions of this research.

Severe Infections are Common in Thiamine Deficiency and May be Related to Cognitive Outcomes: A Cohort Study of 68 Patients With Wernicke-Korsakoff Syndrome

NARCIS (Netherlands)

Wijnia, Jan W.; Oudman, Erik; van Gool, Willem A.; Wierdsma, André I.; Bresser, Esmay L.; Bakker, Jan; van de Wiel, Albert; Mulder, Cornelis L.

2016-01-01

Wernicke encephalopathy can have different clinical outcomes. Although infections may precipitate the encephalopathy itself, it is unknown whether infections also modify the long-term outcome in patients developing Korsakoff syndrome. To determine whether markers of infection, such as white blood

Imbalance between thyroid hormones and the dopaminergic system might be central to the pathophysiology of restless legs syndrome: a hypothesis

Directory of Open Access Journals (Sweden)

Jose Carlos Pereira Jr.

2010-01-01

Full Text Available Data collected from medical literature indicate that dopaminergic agonists alleviate Restless Legs Syndrome symptoms while dopaminergic agonists antagonists aggravate them. Dopaminergic agonists is a physiological regulator of thyroid-stimulating hormone. Dopaminergic agonists infusion diminishes the levels of thyroid hormones, which have the ability to provoke restlessness, hyperkinetic states, tremors, and insomnia. Conditions associated with higher levels of thyroid hormones, such as pregnancy or hyperthyroidism, have a higher prevalence of Restless Legs Syndrome symptoms. Low iron levels can cause secondary Restless Legs Syndrome or aggravate symptoms of primary disease as well as diminish enzymatic activities that are involved in dopaminergic agonists production and the degradation of thyroid hormones. Moreover, as a result of low iron levels, dopaminergic agonists diminishes and thyroid hormones increase. Iron therapy improves Restless Legs Syndrome symptoms in iron deprived patients. Medical hypothesis. To discuss the theory that thyroid hormones, when not counterbalanced by dopaminergic agonists, may precipitate the signs and symptoms underpinning Restless Legs Syndrome. The main cause of Restless Legs Syndrome might be an imbalance between the dopaminergic agonists system and thyroid hormones.

Letter to the Editor: On "Advantages and disadvantages of stiffness instructions when studying postural control" by C.T. Bonnet: You just can't win: Advantages and disadvantages of the postural stability requirement.

Science.gov (United States)

Lajoie, Y; Richer, N; Jehu, D A; Polskaia, N; Saunders, D

2016-05-01

In the examination of postural control, instructions to stand as still as possible are common and promote a relatively unnatural sway pattern. The validity of the stability requirement is discussed in the present commentary in response to the discussion initiated by Cedrick T. Bonnet. The advantages of using the stability requirement include: evaluating unbiased postural control, reducing variability in postural sway, manipulating focus of attention, examining the ability to maintain an upright stance, and ecological validity of testing. The disadvantages include: constraining natural postural sway, increasing the complexity of the control condition, promoting an internal focus of attention, and reducing the ability to detect exploratory behaviour. After evaluating the aforementioned advantages and disadvantages, the present commentary suggests that researchers should strive to provide specific instructions to maintain feet, arm and eye position without specifically requiring participants to reduce their postural sway. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of calcium carbonate and sulfate co-precipitation

KAUST Repository

Zarga, Y.

2013-06-01

Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms. © 2013 Elsevier Ltd.

Risk assessment of precipitation extremes in northern Xinjiang, China

Science.gov (United States)

Yang, Jun; Pei, Ying; Zhang, Yanwei; Ge, Quansheng

2018-05-01

This study was conducted using daily precipitation records gathered at 37 meteorological stations in northern Xinjiang, China, from 1961 to 2010. We used the extreme value theory model, generalized extreme value (GEV) and generalized Pareto distribution (GPD), statistical distribution function to fit outputs of precipitation extremes with different return periods to estimate risks of precipitation extremes and diagnose aridity-humidity environmental variation and corresponding spatial patterns in northern Xinjiang. Spatiotemporal patterns of daily maximum precipitation showed that aridity-humidity conditions of northern Xinjiang could be well represented by the return periods of the precipitation data. Indices of daily maximum precipitation were effective in the prediction of floods in the study area. By analyzing future projections of daily maximum precipitation (2, 5, 10, 30, 50, and 100 years), we conclude that the flood risk will gradually increase in northern Xinjiang. GEV extreme value modeling yielded the best results, proving to be extremely valuable. Through example analysis for extreme precipitation models, the GEV statistical model was superior in terms of favorable analog extreme precipitation. The GPD model calculation results reflect annual precipitation. For most of the estimated sites' 2 and 5-year T for precipitation levels, GPD results were slightly greater than GEV results. The study found that extreme precipitation reaching a certain limit value level will cause a flood disaster. Therefore, predicting future extreme precipitation may aid warnings of flood disaster. A suitable policy concerning effective water resource management is thus urgently required.

Connecting Satellite-Based Precipitation Estimates to Users

Science.gov (United States)

Huffman, George J.; Bolvin, David T.; Nelkin, Eric

2018-01-01

Beginning in 1997, the Merged Precipitation Group at NASA Goddard has distributed gridded global precipitation products built by combining satellite and surface gauge data. This started with the Global Precipitation Climatology Project (GPCP), then the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), and recently the Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement (GPM) mission (IMERG). This 20+-year (and on-going) activity has yielded an important set of insights and lessons learned for making state-of-the-art precipitation data accessible to the diverse communities of users. Merged-data products critically depend on the input sensors and the retrieval algorithms providing accurate, reliable estimates, but it is also important to provide ancillary information that helps users determine suitability for their application. We typically provide fields of estimated random error, and recently reintroduced the quality index concept at user request. Also at user request we have added a (diagnostic) field of estimated precipitation phase. Over time, increasingly more ancillary fields have been introduced for intermediate products that give expert users insight into the detailed performance of the combination algorithm, such as individual merged microwave and microwave-calibrated infrared estimates, the contributing microwave sensor types, and the relative influence of the infrared estimate.

Amazon River Basin Precipitation, 1972-1992

Data.gov (United States)

National Aeronautics and Space Administration — ABSTRACT: The precipitation data is 0.2 degree gridded monthly precipitation data based upon monthly rain data from Peru and Bolivia and daily rain data from Brazil....

Future changes of precipitation characteristics in China

Science.gov (United States)

Wu, S.; Wu, Y.; Wen, J.

2017-12-01

Global warming has the potential to alter the hydrological cycle, with significant impacts on the human society, the environment and ecosystems. This study provides a detailed assessment of potential changes in precipitation characteristics in China using a suite of 12 high-resolution CMIP5 climate models under a medium and a high Representative Concentration Pathways: RCP4.5 and RCP8.5. We examine future changes over the entire distribution of precipitation, and identify any shift in the shape and/or scale of the distribution. In addition, we use extreme-value theory to evaluate the change in probability and magnitude for extreme precipitation events. Overall, China is going to experience an increase in total precipitation (by 8% under RCP4.5 and 12% under RCP8.5). This increase is uneven spatially, with more increase in the west and less increase in the east. Precipitation frequency is projected to increase in the west and decrease in the east. Under RCP4.5, the overall precipitation frequency for the entire China remains largely unchanged (0.08%). However, RCP8.5 projects a more significant decrease in frequency for large part of China, resulting in an overall decrease of 2.08%. Precipitation intensity is likely increase more uniformly, with an overall increase of 11% for RCP4.5 and 19% for RCP8.5. Precipitation increases for all parts of the distribution, but the increase is more for higher quantiles, i.e. strong events. The relative contribution of small quantiles is likely to decrease, whereas contribution from heavy events is likely to increase. Extreme precipitation increase at much higher rates than average precipitation, and high rates of increase are expected for more extreme events. 1-year events are likely to increase by 15%, but 20-year events are going to increase by 21% under RCP4.5, 26% and 40% respectively under RCP8.5. The increase of extreme events is likely to be more spatially uniform.

Regional climate scenarios - A study on precipitation

International Nuclear Information System (INIS)

Hesselbjerg Christensen, J.; Boessing Christensen, O.

2001-01-01

A set of nested climate change simulations for the Nordic region and Denmark has been revisited. In the present work we have re-examined the results of CCMB and MBC with special emphasis on precipitation intensity frequencies, in particular the more extreme part of the frequency distribution. It has been demonstrated that the role of extreme precipitation events appears to be more realistically described in a high-resolution model, in terms of numerical agreement as well as seasonal variation. This is mainly due to a better simulation of deep low-pressure systems and mesoscale circulation. Generally, the analysis has confirmed the results from CCMB, but furthermore a resolution effect has been identified which seems essential to the understanding of climate change effects on the extreme end of the precipitation intensity distribution. In order to analyse the role of the model resolution we have aggregated both the nested model data and observational records to the GCM grid from the driving AOGCM. It was found that, in spite of changes in absolute numbers, the seasonal behaviour of decay constants does not change appreciably because of the aggregation. The RCM results show a seasonal behaviour very similar to an observed data set. It is therefore concluded that the GCM has an unrealistic simulation of the dependence of heavy precipitation on climate, as manifested in seasonal variation. In contrast, the regional simulations remain close to observation in this respect. Furthermore, they agree on a conclusion that extreme precipitation generally scales with average precipitation (no significant change in decay constants were detected), but that crucial summer season may be an exception, exhibiting an anomalous increase in heavy precipitation due to the anthropogenic greenhouse effect. The analysis has only been performed over Denmark due to lack of daily observational data for other regions. It is, however, necessary to extend the work to other areas, for instance

Flood forecasting and uncertainty of precipitation forecasts

International Nuclear Information System (INIS)

Kobold, Mira; Suselj, Kay

2004-01-01

The timely and accurate flood forecasting is essential for the reliable flood warning. The effectiveness of flood warning is dependent on the forecast accuracy of certain physical parameters, such as the peak magnitude of the flood, its timing, location and duration. The conceptual rainfall - runoff models enable the estimation of these parameters and lead to useful operational forecasts. The accurate rainfall is the most important input into hydrological models. The input for the rainfall can be real time rain-gauges data, or weather radar data, or meteorological forecasted precipitation. The torrential nature of streams and fast runoff are characteristic for the most of the Slovenian rivers. Extensive damage is caused almost every year- by rainstorms affecting different regions of Slovenia' The lag time between rainfall and runoff is very short for Slovenian territory and on-line data are used only for now casting. Forecasted precipitations are necessary for hydrological forecast for some days ahead. ECMWF (European Centre for Medium-Range Weather Forecasts) gives general forecast for several days ahead while more detailed precipitation data with limited area ALADIN/Sl model are available for two days ahead. There is a certain degree of uncertainty using such precipitation forecasts based on meteorological models. The variability of precipitation is very high in Slovenia and the uncertainty of ECMWF predicted precipitation is very large for Slovenian territory. ECMWF model can predict precipitation events correctly, but underestimates amount of precipitation in general The average underestimation is about 60% for Slovenian region. The predictions of limited area ALADIN/Si model up to; 48 hours ahead show greater applicability in hydrological forecasting. The hydrological models are sensitive to precipitation input. The deviation of runoff is much bigger than the rainfall deviation. Runoff to rainfall error fraction is about 1.6. If spatial and time distribution

On the complex conductivity signatures of calcite precipitation

Energy Technology Data Exchange (ETDEWEB)

Wu, Yuxin; Hubbard, Susan; Williams, Kenneth Hurst; Ajo-Franklin, Jonathan

2009-11-01

Calcite is a mineral phase that frequently precipitates during subsurface remediation or geotechnical engineering processes. This precipitation can lead to changes in the overall behavior of the system, such as flow alternation and soil strengthening. Because induced calcite precipitation is typically quite variable in space and time, monitoring its distribution in the subsurface is a challenge. In this research, we conducted a laboratory column experiment to investigate the potential of complex conductivity as a mean to remotely monitor calcite precipitation. Calcite precipitation was induced in a glass bead (3 mm) packed column through abiotic mixing of CaCl{sub 2} and Na{sub 2}CO{sub 3} solutions. The experiment continued for 12 days with a constant precipitation rate of {approx}0.6 milimole/d. Visual observations and scanning electron microscopy imaging revealed two distinct phases of precipitation: an earlier phase dominated by well distributed, discrete precipitates and a later phase characterized by localized precipitate aggregation and associated pore clogging. Complex conductivity measurements exhibited polarization signals that were characteristic of both phases of calcite precipitation, with the precipitation volume and crystal size controlling the overall polarization magnitude and relaxation time constant. We attribute the observed responses to polarization at the electrical double layer surrounding calcite crystals. Our experiment illustrates the potential of electrical methods for characterizing the distribution and aggregation state of nonconductive minerals like calcite. Advancing our ability to quantify geochemical transformations using such noninvasive methods is expected to facilitate our understanding of complex processes associated with natural subsurface systems as well as processes induced through engineered treatments (such as environmental remediation and carbon sequestration).

Waste and Simulant Precipitation Issues

International Nuclear Information System (INIS)

Steele, W.V.

2000-01-01

As Savannah River Site (SRS) personnel have studied methods of preparing high-level waste for vitrification in the Defense Waste Processing Facility (DWPF), questions have arisen with regard to the formation of insoluble waste precipitates at inopportune times. One option for decontamination of the SRS waste streams employs the use of an engineered form of crystalline silicotitanate (CST). Testing of the process during FY 1999 identified problems associated with the formation of precipitates during cesium sorption tests using CST. These precipitates may, under some circumstances, obstruct the pores of the CST particles and, hence, interfere with the sorption process. In addition, earlier results from the DWPF recycle stream compatibility testing have shown that leaching occurs from the CST when it is stored at 80 C in a high-pH environment. Evidence was established that some level of components of the CST, such as silica, was leached from the CST. This report describes the results of equilibrium modeling and precipitation studies associated with the overall stability of the waste streams, CST component leaching, and the presence of minor components in the waste streams

Mechanisms and kinetics of precipitate restructuring during irradiation

International Nuclear Information System (INIS)

Potter, D.I.; Wiedersich, H.

1979-01-01

Irradiations were performed at temperatures from 400 to 700 0 C using 3.0-MeV 58 Ni + ions in order to investigate γ'-precipitate restructuring in two model alloys: Ni-12.8 at% Al and Ni-12.7 at% Si. The precipitates coarsened, with the third power of the average diameter proportional to the damage dose. The temperature dependence of the rate constants for irradiated specimens is described in terms of a modified Lifschitz-Slyozov-Wagner coarsening model that includes radiation-enhanced diffusion. Redistribution of precipitate by enhanced precipitation (Ni-Si) or precipitate dissolution (Ni-Al) at point-defect sinks caused maxima in γ' size with dose. Precipitate redistribution at the free surfaces of irradiated thin foils and at γ/γ' particle interfaces is described. (Auth.)

An overlap case of Parry–Romberg syndrome and en coup de sabre with striking ocular involvement and anti-double-stranded DNA positivity

Directory of Open Access Journals (Sweden)

Hatice Atas

2018-01-01

Full Text Available Parry–Romberg syndrome (PRS may overlap localized scleroderma (morphea lesions with linear depression (en coup de sabre [ECDS]. Overlap case with PRS and ECDS was presented. Enophthalmos, uveitis, ocular torticollis, keratic linear precipitates, and anti-double-stranded DNA positivity were identified. Subendothelial keratic precipitates detected by an in vivo laser scanning confocal microscopy were the first profiled in the literature. Patients must be evaluated and followed up carefully by their clinics to prevent misdiagnosis and unnecessary procedures such as surgery of ocular torticollis as muscular torticollis.

Flotation separation of strontium via phosphate precipitation.

Science.gov (United States)

Thanh, Luong H V; Liu, J C

2017-06-01

Flotation separation of strontium (Sr) from wastewater via phosphate precipitation was investigated. While 37.33% of Sr precipitated at highly alkaline pH in the absence of PO 4 3- , it completely precipitated as Sr 3 (PO 4 ) 2 at a molar ratio ([PO 4 3- ]:[Sr 2+ ]) of 0.62 at a lower pH value. The presence of Ca 2+ hindered Sr precipitation, yet it could be overcome by increasing the PO 4 3- dose. Sodium dodecyl sulfate (SDS) was a better collector for dispersed air flotation of Sr 3 (PO 4 ) 2 than cetyl trimethyl ammonium bromide, or mixed collector systems of SDS and saponin. The highest separation efficiency of 97.5% was achieved at an SDS dose of 40 mg/L. The main mechanism in the precipitate flotation is adsorption of anionic SDS on the positively charged surface of colloidal Sr 3 (PO 4 ) 2 via electrostatic interaction. SDS enhanced the aggregation of Sr 3 (PO 4 ) 2 precipitates as the size increased from 1.65 to 28.0 μm, which was beneficial to separation as well.

Climate Prediction Center (CPC) Global Precipitation Time Series

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The global precipitation time series provides time series charts showing observations of daily precipitation as well as accumulated precipitation compared to normal...

Precipitation in the Solar System

Science.gov (United States)

McIntosh, Gordon

2007-01-01

As an astronomy instructor, I am always looking for commonly observed Earthly experiences to help my students and me understand and appreciate similar occurrences elsewhere in the solar system. Recently I wrote a short TPT article on frost. This paper is on the related phenomena of precipitation. Precipitation, so common on most of the Earth's…

Exercise-induced hyperthermia syndrome (canine stress syndrome in four related male English springer spaniels

Directory of Open Access Journals (Sweden)

Thrift E

2017-09-01

Full Text Available Elizabeth Thrift,1 Justin A Wimpole,2 Georgina Child,2 Narelle Brown,1 Barbara Gandolfi,3 Richard Malik4 1Animal Referral Hospital, 2Small Animal Specialist Hospital, Sydney, NSW, Australia; 3Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA; 4Centre for Veterinary Education, University of Sydney, Sydney, NSW, Australia Objective: This retrospective study describes the signalment, clinical presentation, diagnostic findings, and mode of inheritance in four young male English springer spaniel dogs with presumptive canine stress syndrome.Materials and methods: Appropriate cases were located through medical searches of medical records of two large private referral centers. Inclusion criteria comprised of English springer spaniel dogs with tachypnea and hyperthermia that subsequently developed weakness or collapse, with or without signs of hemorrhage, soon after a period of mild-to-moderate exercise. The pedigrees of the four affected dogs, as well as eleven related English springer spaniels, were then analyzed to determine a presumptive mode of genetic inheritance.Results: Four dogs met the inclusion criteria. All four were male, suggesting the possibility of a recessive sex-linked heritable disorder. Pedigree analysis suggests that more dogs may be potentially affected, although these dogs may have never had the concurrent triggering drug/activity/event to precipitate the clinical syndrome. There was complete resolution of clinical signs in three of the four dogs with aggressive symptomatic and supportive therapy, with one dog dying during treatment.Conclusion: Dogs with canine stress syndrome have the potential for rapid recovery if treated aggressively and the complications of the disease (eg, coagulopathy are anticipated. All four dogs were male, suggesting the possibility of a recessive sex-linked mode of inheritance. Further genetic analyses should be strongly considered by those

Ultra-sonic observation in niobium hydride precipitation

International Nuclear Information System (INIS)

Florencio, O.; Pinatti, Dyonisio G.

1982-01-01

The hidrogen embrittlement of exothermic ocluders, had been considered as due to applied stress induced hydride precipitates leading to brittle fracture. The results of simultaneous measurements of macroscopic deformation and elastic change due to hydride precipitation, using the ultrasonic pulse-echo technique are showed. THen it was tested the possibility of kinectis precipitation parameters evoluation. (Author) [pt

U.S. 15 Minute Precipitation Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — U.S. 15 Minute Precipitation Data is digital data set DSI-3260, archived at the National Climatic Data Center (NCDC). This is precipitation data. The primary source...

Kinetics of niobium carbide precipitation in ferrite; Cinetiques de precipitation du carbure de niobium dans la ferrite

Energy Technology Data Exchange (ETDEWEB)

Gendt, D

2001-07-01

The aim of this study is to develop a NbC precipitation modelling in ferrite. This theoretical study is motivated by the fact it considers a ternary system and focus on the concurrence of two different diffusion mechanisms. An experimental study with TEP, SANS and Vickers micro-hardening measurements allows a description of the NbC precipitation kinetics. The mean radius of the precipitates is characterized by TEM observations. To focus on the nucleation stage, we use the Tomographic Atom Probe that analyses, at an atomistic scale, the position of the solute atoms in the matrix. A first model based on the classical nucleation theory and the diffusion-limited growth describes the precipitation of spherical precipitates. To solve the set of equations, we use a numerical algorithm that furnishes an evaluation of the precipitated fraction, the mean radius and the whole size distribution of the particles. The parameters that are the interface energy, the solubility product and the diffusion coefficients are fitted with the data available in the literature and our experimental results. It allows a satisfactory agreement as regards to the simplicity of the model. Monte Carlo simulations are used to describe the evolution of a ternary alloy Fe-Nb-C on a cubic centred rigid lattice with vacancy and interstitial mechanisms. This is realized with an atomistic description of the atoms jumps and their related frequencies. The model parameters are fitted with phase diagrams and diffusion coefficients. For the sake of simplicity, we consider that the precipitation of NbC is totally coherent and we neglect any elastic strain effect. We can observe different kinetic paths: for low supersaturations, we find an expected precipitation of NbC but for higher supersaturations, the very fast diffusivity of carbon atoms conducts to the nucleation of iron carbide particles. We establish that the occurrence of this second phenomenon depends on the vacancy arrival kinetics and can be related

Regime-dependent forecast uncertainty of convective precipitation

Energy Technology Data Exchange (ETDEWEB)

Keil, Christian; Craig, George C. [Muenchen Univ. (Germany). Meteorologisches Inst.

2011-04-15

Forecast uncertainty of convective precipitation is influenced by all scales, but in different ways in different meteorological situations. Forecasts of the high resolution ensemble prediction system COSMO-DE-EPS of Deutscher Wetterdienst (DWD) are used to examine the dominant sources of uncertainty of convective precipitation. A validation with radar data using traditional as well as spatial verification measures highlights differences in precipitation forecast performance in differing weather regimes. When the forecast uncertainty can primarily be associated with local, small-scale processes individual members run with the same variation of the physical parameterisation driven by different global models outperform all other ensemble members. In contrast when the precipitation is governed by the large-scale flow all ensemble members perform similarly. Application of the convective adjustment time scale confirms this separation and shows a regime-dependent forecast uncertainty of convective precipitation. (orig.)

How is climate change impacting precipitation?

Science.gov (United States)

Heidari, A.; Houser, P. R.

2015-12-01

Water is an integrating component of the climate, energy and geochemical cycles, regulating biological and ecological activities at all spatial and temporal scales. The most significant climate warming manifestation would be a change in the distribution of precipitation and evaporation, and the exacerbation of extreme hydrologic events. Due to this phenomenon and the fact that precipitation is the most important component of the water cycle, the assumption of its stationarity for water management and engineering design should be examined closely. The precipitation Annual Maximum Series (AMS) over some stations in Virginia based on in situ data were been used as a starting point to examine this important issue. We analyzed the AMS precipitation on NOAA data for the stations close to Fairfax VA, looked for trends in extreme values, and applied our new method of Generalized Extreme Value (GEV) theory based on quadratic forms to address changes in those extreme values and to quantify non-stationarities. It is very important to address the extreme values of precipitation based on several statistical tests to have better understanding of climate change impact on the extreme water cycle events. In our study we compared our results with the conclusion on NOAA atlas 14 Ap.3 which found no sign of precipitation non-stationarity. We then assessed the impact of this uncertainty in IDF curves on the flood map of Fairfax and compared the results with the classic IDF curves.

Differential Precipitation and Solubilization of Proteins.

Science.gov (United States)

Ryan, Barry J; Kinsella, Gemma K

2017-01-01

Differential protein precipitation is a rapid and economical step in protein purification and is based on exploiting the inherent physicochemical properties of the polypeptide. Precipitation of recombinant proteins, lysed from the host cell, is commonly used to concentrate the protein of choice before further polishing steps with more selective purification columns (e.g., His-Tag, Size Exclusion, etc.). Recombinant proteins can also precipitate naturally as inclusion bodies due to various influences during overexpression in the host cell. Although this phenomenon permits easier initial separation from native proteins, these inclusion bodies must carefully be differentially solubilized so as to reform functional, correctly folded proteins. Here, appropriate bioinformatics tools to aid in understanding a protein's propensity to aggregate and solubilize are explored as a backdrop for a typical protein extraction, precipitation, and selective resolubilization procedure, based on a recombinantly expressed protein.

Arsenic precipitation from metallurgical effluents

International Nuclear Information System (INIS)

Navarro, P.; Vargas, C.; Araya, E.; Martin, I.; Alguacil, F. J.

2004-01-01

In the mining-metallurgical companies different liquid effluents are produced, which can contain a series of dissolved elements that are considered dangerous from an environmental point of view. One of these elements is the arsenic, especially in the state of oxidation +5 that can be precipitated as calcium or iron arsenate. To fulfil the environmental requests it should have in solution a content of arsenic lower than 0,5 mg/l and the obtained solid product should be very stable under the condition in which it will be stored. this work looks for the best conditions of arsenic precipitation, until achieving contents in solution lower than such mentioned concentration. Also, the stability of the precipitates was studied. (Author) 7 refs

Precipitation process for supernate decontamination

International Nuclear Information System (INIS)

Lee, L.M.; Kilpatrick, L.L.

1982-11-01

A precipitation and adsorption process has been developed to remove cesium, strontium, and plutonium from water-soluble, high-level radioactive waste. An existing waste tank serves as the reaction vessel and the process begins with the addition of a solution of sodium tetraphenylborate and a slurry of sodium titanate to the contained waste salt solution. Sodium tetraphenylborate precipitates the cesium and sodium titanate adsorbs the strontium and plutonium. The precipitate/adsorbate is then separated from the decontaminated salt solution by crossflow filtration. This new process offers significant capital savings over an earlier ion exchange process for salt decontamination. Chemical and small-scale engineering studies with actual waste are reported. The effect of many variables on the decontamination factors and filter performance are defined

Precipitation regime influence on oxygen triple-isotope distributions in Antarctic precipitation and ice cores

Science.gov (United States)

Miller, Martin F.

2018-01-01

The relative abundance of 17O in meteoric precipitation is usually reported in terms of the 17O-excess parameter. Variations of 17O-excess in Antarctic precipitation and ice cores have hitherto been attributed to normalised relative humidity changes at the moisture source region, or to the influence of a temperature-dependent supersaturation-controlled kinetic isotope effect during in-cloud ice formation below -20 °C. Neither mechanism, however, satisfactorily explains the large range of 17O-excess values reported from measurements. A different approach, based on the regression characteristics of 103 ln (1 +δ17 O) versus 103 ln (1 +δ18 O), is applied here to previously published isotopic data sets. The analysis indicates that clear-sky precipitation ('diamond dust'), which occurs widely in inland Antarctica, is characterised by an unusual relative abundance of 17O, distinct from that associated with cloud-derived, synoptic snowfall. Furthermore, this distinction appears to be largely preserved in the ice core record. The respective mass contributions to snowfall accumulation - on both temporal and spatial scales - provides the basis of a simple, first-order explanation for the observed oxygen triple-isotope ratio variations in Antarctic precipitation, surface snow and ice cores. Using this approach, it is shown that precipitation during the last major deglaciation, both in western Antarctica at the West Antarctic Ice Sheet (WAIS) Divide and at Vostok on the eastern Antarctic plateau, consisted essentially of diamond dust only, despite a large temperature differential (and thus different water vapour supersaturation conditions) at the two locations. In contrast, synoptic snowfall events dominate the accumulation record throughout the Holocene at both sites.

A Survey of Precipitation Data for Environmental Modeling

Science.gov (United States)

This report explores the types of precipitation data available for environmental modeling. Precipitation is the main driver in the hydrological cycle and modelers use this information to understand water quality and water availability. Models use observed precipitation informatio...

Radiation induced homogeneous precipitation in undersaturated solid-solutions

International Nuclear Information System (INIS)

Cauvin, R.; Martin, G.

1979-01-01

A TEM study of 1 MeV electron irradiated Al 1.9 at% Zn solid solution shows that Zn precipitates form, under irradiation at temperatures well above the Zn solvus temperature outside irradiation. The corresponding upward shift of this temperature is dose rate dependent. This new example of radiation-induced precipitation exhibits unexpected features, which are not accounted for by the available models: (1) no correlation exists between the location of the precipitates and that of the point defects sinks; (2) the precipitation of incoherent β-phase with atomic volume smaller than that of the matrix, and of coherent G.P. zones both occurs; (3) the size of the coherent β precipitates saturates at large dose. A general mechanism for solute concentration fluctuations under irradiation is proposed which qualitatively accounts for the formation of coherent G.P. zones and for the nucleation of solute clusters with more complex structures. A reanalysis of Russell's model (1977) for the growth of incoherent precipitates shows that it may qualitatively account for the observed behavior of the β phase precipitates. (Auth.)

Precipitation in a lead calcium tin anode

International Nuclear Information System (INIS)

Pérez-González, Francisco A.; Camurri, Carlos G.; Carrasco, Claudia A.; Colás, Rafael

2012-01-01

Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 °C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn 3 particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: ► The distance between precipitates in a lead alloy is recorded. ► The relationship between the distance and the cooling rate is established. ► It is found that the strengthening of the alloy depends on the distance between precipitates.

Understanding Bartter syndrome and Gitelman syndrome.

Science.gov (United States)

Fremont, Oliver T; Chan, James C M

2012-02-01

We aim to review the clinical features of two renal tubular disorders characterized by sodium and potassium wasting: Bartter syndrome and Gitelman syndrome. Selected key references concerning these syndromes were analyzed, together with a PubMed search of the literature from 2000 to 2011. The clinical features common to both conditions and those which are distinct to each syndrome were presented. The new findings on the genetics of the five types of Bartter syndrome and the discrete mutations in Gitelman syndrome were reviewed, together with the diagnostic workup and treatment for each condition. Patients with Bartter syndrome types 1, 2 and 4 present at a younger age than classic Bartter syndrome type 3. They present with symptoms, often quite severe in the neonatal period. Patients with classic Bartter syndrome type 3 present later in life and may be sporadically asymptomatic or mildly symptomatic. The severe, steady-state hypokalemia in Bartter syndrome and Gitelman syndrome may abruptly become life-threatening under certain aggravating conditions. Clinicians need to be cognizant of such renal tubular disorders, and promptly treat at-risk patients.

Developing precipitation hardenable high entropy alloys

Science.gov (United States)

Gwalani, Bharat

High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi 2 (0 mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (gamma') and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale gamma' precipitates

Analysis of precipitation in a Cu-Cr-Zr alloy

Institute of Scientific and Technical Information of China (English)

Zhao Mei; Lin Guobiao; Wang Zidong; Zhang Maokui

2008-01-01

Precipites in Cu-0.42%Cr-0.21%Zr alloy were analyzed by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDXS) and transmission electron microscope (TEM). After the solid solution was performed at 980℃ for 2 h, water-quenched and aged at 450℃ for 20 h, the precipite had a bimodal distribution of precipitate size. The coarse precipitates are pure Cr and Cu5Zr, the dispersed fine precipitate is CrCu2(Zr, Mg) and pure Cr ranging from 1 to 50 nm. The coarse phases formed during solidification and were left undissolved during solid solution. The fine precipitates are the hardening precipitates that form due to decomposition of the supersaturated solid solution during aging.

Enhanced precipitation variability decreases grass- and increases shrub-productivity

Science.gov (United States)

Gherardi, Laureano A.; Sala, Osvaldo E.

2015-01-01

Although projections of precipitation change indicate increases in variability, most studies of impacts of climate change on ecosystems focused on effects of changes in amount of precipitation, overlooking precipitation variability effects, especially at the interannual scale. Here, we present results from a 6-y field experiment, where we applied sequences of wet and dry years, increasing interannual precipitation coefficient of variation while maintaining a precipitation amount constant. Increased precipitation variability significantly reduced ecosystem primary production. Dominant plant-functional types showed opposite responses: perennial-grass productivity decreased by 81%, whereas shrub productivity increased by 67%. This pattern was explained by different nonlinear responses to precipitation. Grass productivity presented a saturating response to precipitation where dry years had a larger negative effect than the positive effects of wet years. In contrast, shrubs showed an increasing response to precipitation that resulted in an increase in average productivity with increasing precipitation variability. In addition, the effects of precipitation variation increased through time. We argue that the differential responses of grasses and shrubs to precipitation variability and the amplification of this phenomenon through time result from contrasting root distributions of grasses and shrubs and competitive interactions among plant types, confirmed by structural equation analysis. Under drought conditions, grasses reduce their abundance and their ability to absorb water that then is transferred to deep soil layers that are exclusively explored by shrubs. Our work addresses an understudied dimension of climate change that might lead to widespread shrub encroachment reducing the provisioning of ecosystem services to society. PMID:26417095

Tritium Level in Romanian Precipitation

Energy Technology Data Exchange (ETDEWEB)

Varlam, C.; Stefanescu, I.; Faurescu, I.; Bogdan, D.; Soare, A. [Institute for Cryogenic and Isotope Technologies, Rm. Valcea (Romania); Duliu, O. G. [Faculty of Physics, University of Bucharest, Magurele (Romania)

2013-07-15

Romania is one of the countries that has no station included in GNIP (Global Network of Isotopes in Precipitation) on its territory. This paper presents results regarding the tritium concentration in precipitation for the period 1999-2009. The precipitation fell at the Institute for cryogenic and Isotope technologies (geographical coordinates: altitude 237 m, latitude 45{sup o}02'07' N, longitude 24{sup o}17'03' E) an was collected both individually and as a composite average of each month. It was individually measured and the average was calculated and compared with the tritium concentration measured in the composite sample. tritium concentration levels ranged from 9.9 {+-} 2.1 TU for 2004 and 13.7 {+-} 2.2 TU for 2009. Comparing the arithmetic mean values with the weighted mean for the period of observation, it was noticed that the higher absolute values of the weighted means were constant. It was found that for the calculated monthly average for the period of observation (1999-2009), the months with the maximum tritium concentration are the same as the months with the maximum amount of precipitation. This behaviour is typical for the monitored location. (author)

Analysis of precipitation teleconnections in CMIP models as a measure of model fidelity in simulating precipitation

Science.gov (United States)

Langenbrunner, B.; Neelin, J.; Meyerson, J.

2011-12-01

The accurate representation of precipitation is a recurring issue in global climate models, especially in the tropics. Poor skill in modeling the variability and climate teleconnections associated with El Niño/Southern Oscillation (ENSO) also persisted in the latest Climate Model Intercomparison Project (CMIP) campaigns. Observed ENSO precipitation teleconnections provide a standard by which we can judge a given model's ability to reproduce precipitation and dynamic feedback processes originating in the tropical Pacific. Using CMIP3 Atmospheric Model Intercomparison Project (AMIP) runs as a baseline, we compare precipitation teleconnections between models and observations, and we evaluate these results against available CMIP5 historical and AMIP runs. Using AMIP simulations restricts evaluation to the atmospheric response, as sea surface temperatures (SSTs) in AMIP are prescribed by observations. We use a rank correlation between ENSO SST indices and precipitation to define teleconnections, since this method is robust to outliers and appropriate for non-Gaussian data. Spatial correlations of the modeled and observed teleconnections are then evaluated. We look at these correlations in regions of strong precipitation teleconnections, including equatorial S. America, the "horseshoe" region in the western tropical Pacific, and southern N. America. For each region and season, we create a "normalized projection" of a given model's teleconnection pattern onto that of the observations, a metric that assesses the quality of regional pattern simulations while rewarding signals of correct sign over the region. Comparing this to an area-averaged (i.e., more generous) metric suggests models do better when restrictions on exact spatial dependence are loosened and conservation constraints apply. Model fidelity in regional measures remains far from perfect, suggesting intrinsic issues with the models' regional sensitivities in moist processes.

Multiresolution comparison of precipitation datasets for large-scale models

Science.gov (United States)

Chun, K. P.; Sapriza Azuri, G.; Davison, B.; DeBeer, C. M.; Wheater, H. S.

2014-12-01

Gridded precipitation datasets are crucial for driving large-scale models which are related to weather forecast and climate research. However, the quality of precipitation products is usually validated individually. Comparisons between gridded precipitation products along with ground observations provide another avenue for investigating how the precipitation uncertainty would affect the performance of large-scale models. In this study, using data from a set of precipitation gauges over British Columbia and Alberta, we evaluate several widely used North America gridded products including the Canadian Gridded Precipitation Anomalies (CANGRD), the National Center for Environmental Prediction (NCEP) reanalysis, the Water and Global Change (WATCH) project, the thin plate spline smoothing algorithms (ANUSPLIN) and Canadian Precipitation Analysis (CaPA). Based on verification criteria for various temporal and spatial scales, results provide an assessment of possible applications for various precipitation datasets. For long-term climate variation studies (~100 years), CANGRD, NCEP, WATCH and ANUSPLIN have different comparative advantages in terms of their resolution and accuracy. For synoptic and mesoscale precipitation patterns, CaPA provides appealing performance of spatial coherence. In addition to the products comparison, various downscaling methods are also surveyed to explore new verification and bias-reduction methods for improving gridded precipitation outputs for large-scale models.

Heart failure in patients with sick sinus syndrome treated with single lead atrial or dual-chamber pacing

DEFF Research Database (Denmark)

Riahi, Sam; Nielsen, Jens Cosedis; Hjortshøj, Søren

2012-01-01

AIMS: Previous studies indicate that ventricular pacing may precipitate heart failure (HF). We investigated occurrence of HF during long-term follow-up among patients with sick sinus syndrome (SSS) randomized to AAIR or DDDR pacing. Furthermore, we investigated effects of percentage of ventricular...... patients (17%) with the leads in a non-apical position, HR 0.67, CI 0.45-1.00, P = 0.05. After adjustments this difference was non-significant. The incidence of HF was not associated with %VP (P = 0.57).CONCLUSION: In patients with SSS, HF was not associated with pacing mode, %VP, or ventricular lead...... localization. This suggests that DDDR pacing is safe in patients with SSS without precipitating HF....

Precipitation Matters

Science.gov (United States)

McDuffie, Thomas

2007-01-01

Although weather, including its role in the water cycle, is included in most elementary science programs, any further examination of raindrops and snowflakes is rare. Together rain and snow make up most of the precipitation that replenishes Earth's life-sustaining fresh water supply. When viewed individually, raindrops and snowflakes are quite…

WPA Precipitation Tabulations

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Hourly precipitation data tabulated under the Work Projects Administration (WPA), a New Deal program created to reduce unemployment during the Great Depression....

High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

OpenAIRE

Maria Domankova; Katarína Bártová; Ivan Slatkovský; Peter Pinke

2016-01-01

The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with ...

Identifying external influences on global precipitation

Energy Technology Data Exchange (ETDEWEB)

Marvel, K.; Bonfils, C.

2013-11-11

Changes in global (ocean and land) precipitation are among the most important and least well-understood consequences of climate change. Increasing greenhouse gas concentrations are thought to affect the zonal-mean distribution of precipitation through two basic mechanisms. First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes). Second, changes in atmospheric circulation patterns will lead to poleward displacement of the storm tracks and subtropical dry zones and to a widening of the tropical belt (“dynamic” changes). We demonstrate that both these changes are occurring simultaneously in global precipitation, that this behavior cannot be explained by internal variability alone, and that external influences are responsible for the observed precipitation changes. Whereas existing model experiments are not of sufficient length to differentiate between natural and anthropogenic forcing terms at the 95% confidence level, we present evidence that the observed trends result from human activities.

The Day-1 GPM Combined Precipitation Algorithm: IMERG

Science.gov (United States)

Huffman, G. J.; Bolvin, D. T.; Braithwaite, D.; Hsu, K.; Joyce, R.; Kidd, C.; Sorooshian, S.; Xie, P.

2012-12-01

The Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (GPM) mission (IMERG) algorithm will provide the at-launch combined-sensor precipitation dataset being produced by the U.S. GPM Science Team. IMERG is being developed as a unified U.S. algorithm that takes advantage of strengths in three current U.S. algorithms: - the TRMM Multi-satellite Precipitation Analysis (TMPA), which addresses inter-satellite calibration of precipitation estimates and monthly scale combination of satellite and gauge analyses; - the CPC Morphing algorithm with Kalman Filtering (KF-CMORPH), which provides quality-weighted time interpolation of precipitation patterns following storm motion; and - the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks using a Cloud Classification System (PERSIANN-CCS), which provides a neural-network-based scheme for generating microwave-calibrated precipitation estimates from geosynchronous infrared brightness temperatures, and filters out some non-raining cold clouds. The goal is to provide a long-term, fine-scale record of global precipitation from the entire constellation of precipitation-relevant satellite sensors, with input from surface precipitation gauges. The record will begin January 1998 at the start of the Tropical Rainfall Measuring Mission (TRMM) and extend as GPM records additional data. Although homogeneity is considered desirable, the use of diverse and evolving data sources works against the strict long-term homogeneity that characterizes a Climate Data Record (CDR). This talk will briefly review the design requirements for IMERG, including multiple runs at different latencies (most likely around 4 hours, 12 hours, and 2 months after observation time), various intermediate data fields as part of the IMERG data file, and the plans to bring up IMERG with calibration by TRMM initially, transitioning to GPM when its individual-sensor precipitation algorithms are fully functional

Generation of a stochastic precipitation model for the tropical climate

Science.gov (United States)

Ng, Jing Lin; Abd Aziz, Samsuzana; Huang, Yuk Feng; Wayayok, Aimrun; Rowshon, MK

2017-06-01

A tropical country like Malaysia is characterized by intense localized precipitation with temperatures remaining relatively constant throughout the year. A stochastic modeling of precipitation in the flood-prone Kelantan River Basin is particularly challenging due to the high intermittency of precipitation events of the northeast monsoons. There is an urgent need to have long series of precipitation in modeling the hydrological responses. A single-site stochastic precipitation model that includes precipitation occurrence and an intensity model was developed, calibrated, and validated for the Kelantan River Basin. The simulation process was carried out separately for each station without considering the spatial correlation of precipitation. The Markov chains up to the fifth-order and six distributions were considered. The daily precipitation data of 17 rainfall stations for the study period of 1954-2013 were selected. The results suggested that second- and third-order Markov chains were suitable for simulating monthly and yearly precipitation occurrences, respectively. The fifth-order Markov chain resulted in overestimation of precipitation occurrences. For the mean, distribution, and standard deviation of precipitation amounts, the exponential, gamma, log-normal, skew normal, mixed exponential, and generalized Pareto distributions performed superiorly. However, for the extremes of precipitation, the exponential and log-normal distributions were better while the skew normal and generalized Pareto distributions tend to show underestimations. The log-normal distribution was chosen as the best distribution to simulate precipitation amounts. Overall, the stochastic precipitation model developed is considered a convenient tool to simulate the characteristics of precipitation in the Kelantan River Basin.

Precipitate resolution in an electron irradiated ni-si alloy

Science.gov (United States)

Watanabe, H.; Muroga, T.; Yoshida, N.; Kitajima, K.

1988-09-01

Precipitate resolution processes in a Ni-12.6 at% Si alloy under electron irradiation have been observed by means of HVEM. Above 400°C, growth and resolution of Ni 3Si precipitates were observed simultaneously. The detail stereoscopic observation showed that the precipitates close to free surfaces grew, while those in the middle of a specimen dissolved. The critical dose when the precipitates start to shrink increases with increasing the depth. This depth dependence of the precipitate behavior under irradiation has a close relation with the formation of surface precipitates and the growth of solute depleted zone beneath them. The temperature and dose dependence of the resolution rate showed that the precipitates in the solute depleted zone dissolved by the interface controlled process of radiation-enhanced diffusion.

Study on Thorium Hidroxide and Ammonium Diuranate precipitation

International Nuclear Information System (INIS)

Damunir; Sukarsono, R; Busron-Masduki; Indra-Suryawan

1996-01-01

Thorium hydroxide and ammonium diuranate precipitation studied by the reaction of mixed thorium nitrate and uranyl nitrate using ammonium hydroxide. The purposes of this research was study of pH condition. U/Th ratio and NH 4 OH concentration on the precipitation. Mixed of thorium nitrate and uranyl nitrate 50 ml was reacted by excess ammonium hydroxide 2 - 10 M, pH 4-8, 40-80 o C of temperature and 5 - 100 % ratio of U/Th. The best of precipitation depend on thorium and uranium content on the precipitation. The experiment result for the best condition of precipitation was 25 % of ratio U/Th, pH 6 - 8, 60-80 o C of temperature, and 6 - 10 M concentration of ammonium hydroxide, was produced precipitate by 3,938 - 5,455 weight percent of mean concentration of U and 22,365-31,873 weight percent of mean concentration of Th

Spatio-temporal variability of several eco-precipitation indicators in China

Science.gov (United States)

Guo, B. B.; Zhang, J.; Wang, F.

2016-12-01

Climate change is expected to have large impacts on the eco-hydrological processes. Precipitation as one of the most important meteorological factors is a significant parameter in ecohydrology. Many studies and precipitation indexes focused on the long-term precipitation variability have been put forward. However, these former studies did not consider the vegetation response and these indexes could not reflect it efficiently. Eco-precipitation indicators reflecting the features and patterns of precipitations and serving as significant input parameters of eco-hydrological models are of paramount significance to the studies of these models. Therefore we proposed 4 important eco-precipitation indicators—Precipitation Variability Index (PVI), Precipitation Occurrence Rate (λ), Mean Precipitation Depth (1/θ) and Annual Precipitation (AP). The PVI index depicts the precipitation variability with a value of zero for perfectly uniform and increases as precipitation events become more sporadic. The λ, 1/θ and AP depict the precipitation frequency, intensity and annual amount, respectively. With large precipitation and vegetation discrepancies, China is selected as a study area. Firstly, these indicators are calculated separately with 55-years (1961-2015) daily precipitation time-series from 693 weather stations in China. Then, the temporal trend is analyzed through Mann-Kendall (MK) test and parametric t-test in annual time scale. Furthermore, the spatial distribution is analyzed through the spatial interpolation tools ANUsplin. The result shows that: (1) 1/θ increased significantly (4.59cm/10yr) while λ decreased significantly (1.54 days/10yr), which means there is an increasing trend of extreme precipitation events; (2)there is a significant downward trend of PVI, which means the rhythm of precipitation has a uniform and concentrated trend; (3) AP increased insignificantly (0.57mm/10yr); and (4)the MK test of these indicators shows that there is saltation of �

Continuous precipitation process of plutonium salts

International Nuclear Information System (INIS)

Richard, P.

1967-03-01

This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [fr

Successes with the Global Precipitation Measurement (GPM) Mission

Science.gov (United States)

Skofronick-Jackson, Gail; Huffman, George; Stocker, Erich; Petersen, Walter

2016-01-01

Water is essential to our planet Earth. Knowing when, where and how precipitation falls is crucial for understanding the linkages between the Earth's water and energy cycles and is extraordinarily important for sustaining life on our planet during climate change. The Global Precipitation Measurement (GPM) Core Observatory spacecraft launched February 27, 2014, is the anchor to the GPM international satellite mission to unify and advance precipitation measurements from a constellation of research and operational sensors to provide "next-generation" precipitation products. GPM is currently a partnership between NASA and the Japan Aerospace Exploration Agency (JAXA). Status and successes in terms of spacecraft, instruments, retrieval products, validation, and impacts for science and society will be presented. Precipitation, microwave, satellite

Recent advances in precipitation-bias correction and application

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

Significant progresses have been made in recent years in precipitation data analyses at regional to global scales. This paper re-views and synthesizes recent advances in precipitation-bias corrections and applications in many countries and over the cold re-gions. The main objective of this review is to identify and examine gaps in regional and national precipitation-error analyses. This paper also discusses and recommends future research needs and directions. More effort and coordination are necessary in the determinations of precipitation biases on large regions across national borders. It is important to emphasize that bias cor-rections of precipitation measurements affect both water budget and energy balance calculations, particularly over the cold regions.

Precipitation Nowcast using Deep Recurrent Neural Network

Science.gov (United States)

Akbari Asanjan, A.; Yang, T.; Gao, X.; Hsu, K. L.; Sorooshian, S.

2016-12-01

An accurate precipitation nowcast (0-6 hours) with a fine temporal and spatial resolution has always been an important prerequisite for flood warning, streamflow prediction and risk management. Most of the popular approaches used for forecasting precipitation can be categorized into two groups. One type of precipitation forecast relies on numerical modeling of the physical dynamics of atmosphere and another is based on empirical and statistical regression models derived by local hydrologists or meteorologists. Given the recent advances in artificial intelligence, in this study a powerful Deep Recurrent Neural Network, termed as Long Short-Term Memory (LSTM) model, is creatively used to extract the patterns and forecast the spatial and temporal variability of Cloud Top Brightness Temperature (CTBT) observed from GOES satellite. Then, a 0-6 hours precipitation nowcast is produced using a Precipitation Estimation from Remote Sensing Information using Artificial Neural Network (PERSIANN) algorithm, in which the CTBT nowcast is used as the PERSIANN algorithm's raw inputs. Two case studies over the continental U.S. have been conducted that demonstrate the improvement of proposed approach as compared to a classical Feed Forward Neural Network and a couple simple regression models. The advantages and disadvantages of the proposed method are summarized with regard to its capability of pattern recognition through time, handling of vanishing gradient during model learning, and working with sparse data. The studies show that the LSTM model performs better than other methods, and it is able to learn the temporal evolution of the precipitation events through over 1000 time lags. The uniqueness of PERSIANN's algorithm enables an alternative precipitation nowcast approach as demonstrated in this study, in which the CTBT prediction is produced and used as the inputs for generating precipitation nowcast.

Harmonic analysis of the precipitation in Greece

Science.gov (United States)

Nastos, P. T.; Zerefos, C. S.

2009-04-01

Greece is a country with a big variety of climates due to its geographical position, to the many mountain ranges and also to the multifarious and long coastline. The mountainous volumes are of such orientation that influences the distribution of the precipitation, having as a result, Western Greece to present great differentiations from Central and Eastern Greece. The application of harmonic analysis to the annual variability of precipitation is the goal of this study, so that the components, which compose the annual variability, be elicited. For this purpose, the mean monthly precipitation data from 30 meteorological stations of National Meteorological Service were used for the time period 1950-2000. The initial target is to reduce the number of variables and to detect structure in the relationships between variables. The most commonly used technique for this purpose is the application of Factor Analysis to a table having as columns the meteorological stations-variables and rows the monthly mean precipitation, so that 2 main factors were calculated, which explain the 98% of total variability of precipitation in Greece. Factor 1, representing the so-called uniform field and interpreting the most of the total variance, refers in fact to the Mediterranean depressions, affecting mainly the West of Greece and also the East Aegean and the Asia Minor coasts. In the process, the Fourier Analysis was applied to the factor scores extracted from the Factor Analysis, so that 2 harmonic components are resulted, which explain above the 98% of the total variability of each main factor, and are due to different synoptic and thermodynamic processes associated with Greece's precipitation construction. Finally, the calculation of the time of occurrence of the maximum precipitation, for each harmonic component of each one of the two main factors, gives the spatial distribution of appearance of the maximum precipitation in the Hellenic region.

Calcite precipitates in Slovenian bottled waters.

Science.gov (United States)

Stanič, Tamara Ferjan; Miler, Miloš; Brenčič, Mihael; Gosar, Mateja

2017-06-01

Storage of bottled waters in varying ambient conditions affects its characteristics. Different storage conditions cause changes in the initial chemical composition of bottled water which lead to the occurrence of precipitates with various morphologies. In order to assess the relationship between water composition, storage conditions and precipitate morphology, a study of four brands of Slovenian bottled water stored in PET bottles was carried out. Chemical analyses of the main ions and measurements of the physical properties of water samples were performed before and after storage of water samples at different ambient conditions. SEM/EDS analysis of precipitates was performed after elapsed storage time. The results show that the presence of Mg 2+ , SO 4 2- , SiO 2 , Al, Mn and other impurities such as K + , Na + , Ba and Sr in the water controlled precipitate morphology by inhibiting crystal growth and leading to elongated rhombohedral calcite crystal forms which exhibit furrowed surfaces and calcite rosettes. Different storage conditions, however, affected the number of crystallization nuclei and size of calcite crystals. Hollow calcite spheres composed of cleavage rhombohedrons formed in the water with variable storage conditions by a combination of evaporation and precipitation of water droplets during high temperatures or by the bubble templating method.

STUDY OF TCP PHASE PRECIPITATING IN GH4199 SUPERALLOY

Institute of Scientific and Technical Information of China (English)

T．Cui; Y．S．Zhang; S．W．Guo; L．Wang; H．C．Yang

2004-01-01

The precipitating regulation and mechanism of TCP phase (μ phase and σ phase) are studied, using electron hole number (EHN) theory, phase analysis technology and TEM observation. The results indicate that the EHN in studied alloy is 2.311-2.348 which is higher than that of critical EHN of μ phase precipitate (2.30), so μ phase could precipitate if there is enough thermo-exposition. In contrast, the calculated EHN is less than that of critical EHN of σ phase precipitate (2.52). However the σ phase is also observed by TEM.Enrich of Cr and Mo around γ phase after γ' phase precipitated leads to σ phase precipitated.

Detection of the relationship between peak temperature and extreme precipitation

Science.gov (United States)

Yu, Y.; Liu, J.; Zhiyong, Y.

2017-12-01

Under the background of climate change and human activities, the characteristics and pattern of precipitation have changed significantly in many regions. As the political and cultural center of China, the structure and character of precipitation in Jingjinji District has varied dramatically in recent years. In this paper, the daily precipitation data throughout the period 1960-2013 are selected for analyzing the spatial-temporal variability of precipitation. The results indicate that the frequency and intensity of precipitation presents an increasing trend. Based on the precipitation data, the maximum, minimum and mean precipitation in different temporal and spatial scales is calculated respectively. The temporal and spatial variation of temperature is obtained by using statistical methods. The relationship between temperature and precipitation in different range is analyzed. The curve relates daily precipitation extremes with local temperatures has a peak structure, increasing at the low-medium range of temperature variations but decreasing at high temperatures. The relationship between extreme precipitation is stronger in downtown than that in suburbs.

High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

Directory of Open Access Journals (Sweden)

Maria Domankova

2016-07-01

Full Text Available The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with the corresponding incubation period 2.5 min.

Tritium time series in precipitation of Rm. Valcea, Romania.

Science.gov (United States)

Varlam, Carmen; Duliu, Octavian G; Faurescu, Ionut; Vagner, Irina; Faurescu, Denisa

2016-01-01

Following tritium concentration records in precipitation for the period 1999-2013 and tritium concentration behaviour during this period for the Ramnicu Valcea (Rm. Valcea) location, the tritium level of individual precipitations of the late spring and summer for the 2009-2013 period was investigated. Despite good correlation between monthly mean tritium concentrations and monthly mean precipitations over the 15-year period of observations (Pearson coefficient 0.87), the individual precipitations had no linear correlation between the tritium concentration and the amount of precipitation.

Precipitation in a lead calcium tin anode

Energy Technology Data Exchange (ETDEWEB)

Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

2012-02-15

Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

Projections of the Ganges-Brahmaputra precipitation: downscaled from GCM predictors

Science.gov (United States)

Pervez, Md Shahriar; Henebry, Geoffrey M.

2014-01-01

Downscaling Global Climate Model (GCM) projections of future climate is critical for impact studies. Downscaling enables use of GCM experiments for regional scale impact studies by generating regionally specific forecasts connecting global scale predictions and regional scale dynamics. We employed the Statistical Downscaling Model (SDSM) to downscale 21st century precipitation for two data-sparse hydrologically challenging river basins in South Asia—the Ganges and the Brahmaputra. We used CGCM3.1 by Canadian Center for Climate Modeling and Analysis version 3.1 predictors in downscaling the precipitation. Downscaling was performed on the basis of established relationships between historical Global Summary of Day observed precipitation records from 43 stations and National Center for Environmental Prediction re-analysis large scale atmospheric predictors. Although the selection of predictors was challenging during the set-up of SDSM, they were found to be indicative of important physical forcings in the basins. The precipitation of both basins was largely influenced by geopotential height: the Ganges precipitation was modulated by the U component of the wind and specific humidity at 500 and 1000 h Pa pressure levels; whereas, the Brahmaputra precipitation was modulated by the V component of the wind at 850 and 1000 h Pa pressure levels. The evaluation of the SDSM performance indicated that model accuracy for reproducing precipitation at the monthly scale was acceptable, but at the daily scale the model inadequately simulated some daily extreme precipitation events. Therefore, while the downscaled precipitation may not be the suitable input to analyze future extreme flooding or drought events, it could be adequate for analysis of future freshwater availability. Analysis of the CGCM3.1 downscaled precipitation projection with respect to observed precipitation reveals that the precipitation regime in each basin may be significantly impacted by climate change

European climate change experiments on precipitation change

DEFF Research Database (Denmark)

Beier, Claus

Presentation of European activities and networks related to experiments and databases within precipitation change......Presentation of European activities and networks related to experiments and databases within precipitation change...

Influence of aerosol on regional precipitation in North China

Institute of Scientific and Technical Information of China (English)

DUAN Jing; MAO JieTai

2009-01-01

The possible anthropogenic aerosol effect on regional precipitation is analyzed based on the historical data of precipitation and visibility of North China. At first, the precipitation amounts from 1960 to 1979 are considered as natural background values in our study for relatively less intensive industrial activi-ties and light air pollution during that period of time, then the region is divided into different subregions by applying the clustering method including the significance test of station rainfall correlations to the time series of 10-day mean rainfall amounts in this period. Based on the rule that the precipitation characteristics are similar in the same clustering region, the correlation of precipitation amounts among all stations in each region is thus established. Secondly, for the period from 1990 to 2005, during which, the economy had experienced a rapid development in this region, the variations of visibility at each station are analyzed. The stations with the absolute change in visibility less than 0.1 km/a are used as the reference stations, at which it is assumed that precipitation has not been seriously influ-enced by anthropogenic aerosols. Then the rainfall amounts of reference stations are used to estimate the natural precipitation values of the other stations in each clustering region. The difference between estimated precipitation and measured precipitation amount is thought to result from changes in an-thropogenic aerosols. These changes in precipitation amounts caused by anthropogenic aerosols at each station are calculated using the 10-day mean rainfall values from 1990 to 2005. The analysis re-suits obtained with this method are remarkable if it passes the significance test, and therefore, the suppression of regional precipitation over the region by anthropogenic aerosol is proved. It is found that this effect is most remarkable in summer. The influence of anthropogenic aerosols on convective precipitation possibly plays an important

The role of intermetallic precipitates in Ti-62222S

Energy Technology Data Exchange (ETDEWEB)

Evans, D J [US Air Force Mater. Directorate Wright Lab., Wright Patterson AFB, OH (United States); Broderick, T F [US Air Force Mater. Directorate Wright Lab., Wright Patterson AFB, OH (United States); Woodhouse, J B [UES Inc, Dayton, OH (United States); Hoenigman, J R [Wright State Univ., Dayton, OH (United States). Research Inst.

1996-08-15

Samples of Ti-62222-0.23wt.%Si were heat treated and aged at temperatures ranging from 1150 F to 1500 F with the view of effecting selective precipitation of {alpha}{sub 2} precipitates and silicides (i.e. Ti{sub x}Zr{sub 5-x}Si{sub 3}). The effect of these intermetallic precipitates on the mechanical properties and fracture morphology was assessed via three separate microstructural conditions: Ti-62222S with {alpha}{sub 2} precipitates, Ti-62222S with {alpha}{sub 2} and silicide precipitates, and Ti-62222S with silicide precipitates. Both types of intermetallic precipitate appear to lower the fracture toughness, however {alpha}{sub 2} promotes intergranular fracture while silicides lead to transgranular failure and dimpling. The combined presence of the {alpha}{sub 2} and silicides leads to mixed mode failure. Further, since {alpha}{sub 2} is present in the {alpha} phase and silicides precipitate out in the {beta} phase, it appears that the effect of each of these intermetallics in Ti-62222S is additive rather than synergistic. (orig.)

Precipitation of Epsilon Copper in Ferrite Antibacterial Stainless Steel

Institute of Scientific and Technical Information of China (English)

Zhixia ZHANG; Gang LIN; Zhou XU

2008-01-01

The precipitation of epsilon copper at 1023 K ageing in ferrite antibacterial stainless steel was investigated by a combination of electron microscopy and micro-Vickers hardness measurement. The results show that epsilon copper precipitation occurs within 90 s. Complex rnultilayer structure confirmed as twins and stacking faults on {111}ε-Cu planes was observed in the precipitates. The precipitates grow by the lengthwise enlargement of a set of parallel layers, having [111]ε-Cu and [112]ε-Cu preferred growth orientations. The volume fraction of precipitates f formed within 120 min can be predicted by a modified Avrami equation (In 1/1-f= kt+b).Simultaneously, substituent atom clusters with a size of 5-10 nm was found to occur in the solution and cause matrix strain. The precipitate morphology and distribution on the surface of ferrite antibacterial stainlesss teel are associated with surface crystallographic orientation of the matrix. The precipitates are predominantly located within the ferrite grains of orientation. The precipitates located on {111}α-Fe surface planes have sphere or ellipse shape.

Two case studies on NARCCAP precipitation extremes

Science.gov (United States)

Weller, Grant B.; Cooley, Daniel; Sain, Stephan R.; Bukovsky, Melissa S.; Mearns, Linda O.

2013-09-01

We introduce novel methodology to examine the ability of six regional climate models (RCMs) in the North American Regional Climate Change Assessment Program (NARCCAP) ensemble to simulate past extreme precipitation events seen in the observational record over two different regions and seasons. Our primary objective is to examine the strength of daily correspondence of extreme precipitation events between observations and the output of both the RCMs and the driving reanalysis product. To explore this correspondence, we employ methods from multivariate extreme value theory. These methods require that we account for marginal behavior, and we first model and compare climatological quantities which describe tail behavior of daily precipitation for both the observations and model output before turning attention to quantifying the correspondence of the extreme events. Daily precipitation in a West Coast region of North America is analyzed in two seasons, and it is found that the simulated extreme events from the reanalysis-driven NARCCAP models exhibit strong daily correspondence to extreme events in the observational record. Precipitation over a central region of the United States is examined, and we find some daily correspondence between winter extremes simulated by reanalysis-driven NARCCAP models and those seen in observations, but no such correspondence is found for summer extremes. Furthermore, we find greater discrepancies among the NARCCAP models in the tail characteristics of the distribution of daily summer precipitation over this region than seen in precipitation over the West Coast region. We find that the models which employ spectral nudging exhibit stronger tail dependence to observations in the central region.

Precipitates/Salts Model Sensitivity Calculation

International Nuclear Information System (INIS)

Mariner, P.

2001-01-01

The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation on potential seepage waters within a potential repository drift. This work is developed and documented using procedure AP-3.12Q, ''Calculations'', in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The specific objective of this calculation is to examine the sensitivity and uncertainties of the Precipitates/Salts model. The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b). The calculation in the current document examines the effects of starting water composition, mineral suppressions, and the fugacity of carbon dioxide (CO 2 ) on the chemical evolution of water in the drift

Precipitation Indices Low Countries

Science.gov (United States)

van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

2009-09-01

Since 1995, KNMI published a series of books(1), presenting an annual reconstruction of weather and climate in the Low Countries, covering the period AD 763-present, or roughly, the last millennium. The reconstructions are based on the interpretation of documentary sources predominantly and comparison with other proxies and instrumental observations. The series also comprises a number of classifications. Amongst them annual classifications for winter and summer temperature and for winter and summer dryness-wetness. The classification of temperature have been reworked into peer reviewed (2) series (AD 1000-present) of seasonal temperatures and temperature indices, the so called LCT (Low Countries Temperature) series, now incorporated in the Millennium databases. Recently we started a study to convert the dryness-wetness classifications into a series of precipitation; the so called LCP (Low Countries Precipitation) series. A brief outline is given here of the applied methodology and preliminary results. The WMO definition for meteorological drought has been followed being that a period is called wet respectively dry when the amount of precipitation is considerable more respectively less than usual (normal). To gain a more quantitative insight for four locations, geographically spread over the Low Countries area (De Bilt, Vlissingen, Maastricht and Uccle), we analysed the statistics of daily precipitation series, covering the period 1900-present. This brought us to the following definition, valid for the Low Countries: A period is considered as (very) dry respectively (very) wet if over a continuous period of at least 60 days (~two months) cq 90 days (~three months) on at least two out of the four locations 50% less resp. 50% more than the normal amount for the location (based on the 1961-1990 normal period) has been measured. This results into the following classification into five drought classes hat could be applied to non instrumental observations: Very wet period

Mercury Wet Scavenging and Deposition Differences by Precipitation Type.

Science.gov (United States)

Kaulfus, Aaron S; Nair, Udaysankar; Holmes, Christopher D; Landing, William M

2017-03-07

We analyze the effect of precipitation type on mercury wet deposition using a new database of individual rain events spanning the contiguous United States. Measurements from the Mercury Deposition Network (MDN) containing single rainfall events were identified and classified into six precipitation types. Mercury concentrations in surface precipitation follow a power law of precipitation depth that is modulated by precipitation system morphology. After controlling for precipitation depth, the highest mercury deposition occurs in supercell thunderstorms, with decreasing deposition in disorganized thunderstorms, quasi-linear convective systems (QLCS), extratropical cyclones, light rain, and land-falling tropical cyclones. Convective morphologies (supercells, disorganized, and QLCS) enhance wet deposition by a factor of at least 1.6 relative to nonconvective morphologies. Mercury wet deposition also varies by geographic region and season. After controlling for other factors, we find that mercury wet deposition is greater over high-elevation sites, seasonally during summer, and in convective precipitation.

Seizure precipitants (triggering factors) in patients with epilepsy.

Science.gov (United States)

Ferlisi, Monica; Shorvon, Simon

2014-04-01

adult epilepsy clinic population: (a) to identify the frequency of seizure precipitants (triggering factors) and their relative frequency in those with psychiatric disorders, and in those in remission or with active epilepsy, differences in frequency with regard to gender, seizure duration, number of drugs taken; (b) to determine which precipitants patients most commonly report; and (c) to identify differences in the distribution of precipitants among generalized, temporal, and extratemporal epilepsies. Consecutive patients attending a tertiary-care epilepsy clinic were prospectively and an open personal interview to identify and characterize seizure precipitants. Information about the epilepsy and clinical characteristics of patients was collected during the interview and from medical records. Of 104 patients, 97% cited at least one precipitant. Stress, sleep deprivation, and fatigue were the most frequently reported precipitants. Patients with psychological comorbidities reported a greater percentage of seizures with seizure precipitants. Patients with idiopathic generalized epilepsy seemed to be more sensitive to seizures during awakening and sleep deprivation, patients with extratemporal epilepsy reported more frequent seizures during sleep. There were no differences in frequency or type of seizure precipitants with regard to gender, seizure duration or frequency, and the number of antiepileptic drugs taken. The findings may have implications for the better management of epilepsy by increasing a focus on nonpharmacological therapy. The implications of the findings for nosology and causation of epilepsy are also briefly discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

Scale-up of precipitation processes

OpenAIRE

Zauner, R.

1999-01-01

This thesis concerns the scale-up of precipitation processes aimed at predicting product particle characteristics. Although precipitation is widely used in the chemical and pharmaceutical industry, successful scale-up is difficult due to the absence of a validated methodology. It is found that none of the conventional scale-up criteria reported in the literature (equal power input per unit mass, equal tip speed, equal stirring rate) is capable of predicting the experimentally o...

An integrated computational tool for precipitation simulation

Science.gov (United States)

Cao, W.; Zhang, F.; Chen, S.-L.; Zhang, C.; Chang, Y. A.

2011-07-01

Computer aided materials design is of increasing interest because the conventional approach solely relying on experimentation is no longer viable within the constraint of available resources. Modeling of microstructure and mechanical properties during precipitation plays a critical role in understanding the behavior of materials and thus accelerating the development of materials. Nevertheless, an integrated computational tool coupling reliable thermodynamic calculation, kinetic simulation, and property prediction of multi-component systems for industrial applications is rarely available. In this regard, we are developing a software package, PanPrecipitation, under the framework of integrated computational materials engineering to simulate precipitation kinetics. It is seamlessly integrated with the thermodynamic calculation engine, PanEngine, to obtain accurate thermodynamic properties and atomic mobility data necessary for precipitation simulation.

Using Extreme Tropical Precipitation Statistics to Constrain Future Climate States

Science.gov (United States)

Igel, M.; Biello, J. A.

2017-12-01

Tropical precipitation is characterized by a rapid growth in mean intensity as the column humidity increases. This behavior is examined in both a cloud resolving model and with high-resolution observations of precipitation and column humidity from CloudSat and AIRS, respectively. The model and the observations exhibit remarkable consistency and suggest a new paradigm for extreme precipitation. We show that the total precipitation can be decomposed into a product of contributions from a mean intensity, a probability of precipitation, and a global PDF of column humidity values. We use the modeling and observational results to suggest simple, analytic forms for each of these functions. The analytic representations are then used to construct a simple expression for the global accumulated precipitation as a function of the parameters of each of the component functions. As the climate warms, extreme precipitation intensity and global precipitation are expected to increase, though at different rates. When these predictions are incorporated into the new analytic expression for total precipitation, predictions for changes due to global warming to the probability of precipitation and the PDF of column humidity can be made. We show that strong constraints can be imposed on the future shape of the PDF of column humidity but that only weak constraints can be set on the probability of precipitation. These are largely imposed by the intensification of extreme precipitation. This result suggests that understanding precisely how extreme precipitation responds to climate warming is critical to predicting other impactful properties of global hydrology. The new framework can also be used to confirm and discount existing theories for shifting precipitation.

[Maxillofacial and dental abnormalities in some multiple abnormality syndromes. "Cri du chat" syndrome, Wilms' tumor-aniridia syndrome; Sotos syndrome; Goldenhar syndrome].

Science.gov (United States)

Berio, A; Trucchi, R; Meliota, M

1992-05-01

The paper describes the maxillo-facial and dental anomalies observed in some chromosome and non-chromosome poly-malformative syndromes ("Cri du chat" syndrome; Wilms' tumour; Sotos' syndrome; Goldenhar's syndrome). The Authors emphasise the possibility of diagnosing these multiple deformity syndromes from maxillo-facial alterations in early infancy; anomalous tooth position and structure cal also be successfully treated immediately after the first appearance of teeth. This is a particularly promising field of pediatrics and preventive pediatric medicine.

Influence of Subtropical Jetstream on Arabian Gulf Precipitation

Science.gov (United States)

Sandeep, S.; Pauluis, O.; Ravindran, A. M.; TP, S.

2017-12-01

The Arabian Gulf and surrounding regions are predominantly arid. However, this region hosts a large population due to the intense economic activity that is centered on the exploration of natural resources in and around the Arabian Gulf. Thus, few precipitation events that occur during boreal winter are important for society and ecology of this region. The mechanisms of winter precipitation over the Gulf are not well understood, partly due to a lack of long term meteorological observation. Here we explore the dynamics of Arabian Gulf winter precipitation events using available observations and a high resolution atmospheric model simulation. Our analyses show that the northern Gulf receives about six times more precipitation than the southern Gulf. Often, the southern Gulf precipitation forms as a result of downstream development of northern Gulf disturbance. The southward movement of northern Gulf disturbances is influenced by the location of subtropical jet. The probability of a northern Gulf precipitating weather system to move south is higher when the subtropical jet is located equatorward of 30°N. The equatorward position of jet favors the penetration of mid-latitude weather systems over the Arabian Peninsula, which in turn pushes the Arabian anticyclone eastward and triggers moisture transport from the Arabian Sea that is essential for southern Gulf precipitation events.

ARM Cloud Aerosol Precipitation Experiment (ACAPEX) Science Plan

Energy Technology Data Exchange (ETDEWEB)

Leung, L. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Prather, K. [Scripps Institution of Oceanography, La Jolla, CA (United States); Ralph, R. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Rosenfeld, D. [The Hebrew University of Jerusalem (Israel); Spackman, R. [Science and Technology Corporation (STC), Hampton, VA (United States); DeMott, P. [Colorado State Univ., Fort Collins, CO (United States); Fairall, C. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Fan, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hagos, S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hughes, M. [National Oceanic and Atmospheric Administration, Washington, DC (United States); Long, C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rutledge, S. [Colorado State Univ., Fort Collins, CO (United States); Waliser, D. [National Aeronautics and Space Administration (NASA), Washington, DC (United States); Wang, H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-09-01

The western U.S. receives precipitation predominantly during the cold season when storms approach from the Pacific Ocean. The snowpack that accumulates during winter storms provides about 70-90% of water supply for the region. Understanding and modeling the fundamental processes that govern the large precipitation variability and extremes in the western U.S. is a critical test for the ability of climate models to predict the regional water cycle, including floods and droughts. Two elements of significant importance in predicting precipitation variability in the western U.S. are atmospheric rivers and aerosols. Atmospheric rivers (ARs) are narrow bands of enhanced water vapor associated with the warm sector of extratropical cyclones over the Pacific and Atlantic oceans. Because of the large lower-tropospheric water vapor content, strong atmospheric winds and neutral moist static stability, some ARs can produce heavy precipitation by orographic enhancement during landfall on the U.S. West Coast. While ARs are responsible for a large fraction of heavy precipitation in that region during winter, much of the rest of the orographic precipitation occurs in post-frontal clouds, which are typically quite shallow, with tops just high enough to pass the mountain barrier. Such clouds are inherently quite susceptible to aerosol effects on both warm rain and ice precipitation-forming processes.

CALCULATION: PRECIPITATION CHARACTERISITICS FOR STORM WATER MANAGEMENT

International Nuclear Information System (INIS)

D. Ambos

2000-01-01

This Calculation is intended to satisfy engineering requirements for maximum 60-minute precipitation amounts for 50 and 100-year return periods at and near Yucca Mountain. This data requirement is documented in the ''Interface Control Document for Support Operations to Surface Facilities Operations Functional and Organizational Interfaces'' (CRWMS M and O 1998a). These developed data will supplement the information on 0.1 hour to 6-hour (in 0.1-hour increments) probable maximum precipitation (PMP) presented in the report, ''Precipitation Design Criteria for Storm Water Management'' (CRWMS M and O 1998b). The Reference Information Base (RIB) item, Precipitation ''Characteristics for Storm Water Management'' (M09902RIB00045 .OOO), was developed based on CRWMS M and O (1998b) and will be supplemented (via revision) with the information developed in this Calculation. The ''Development Plan for the Calculation: Precipitation Characteristics for Storm Water Management'' (CRWMS M and O 2000) was prepared in accordance with AP-2.l3Q, ''Technical Product Development Planning''. This calculation was developed in accordance with AP-3.12Q, Rev. O/ICN 2

Linkages between Icelandic Low position and SE Greenland winter precipitation

Science.gov (United States)

Berdahl, M.; Rennermalm, A. K.; Hammann, A. C.; Mioduszewski, J.; Hameed, S.; Tedesco, M.; Stroeve, J. C.; Mote, T. L.

2015-12-01

Greenland's largest flux of precipitation occurs in its Southeast (SE) region. An understanding of the mechanisms controlling precipitation in this region is lacking despite its disproportionate importance in the mass balance of Greenland and the consequent contributions to sea level rise. We use weather station data from the Danish Meteorological Institute to reveal the governing influences on precipitation in SE Greenland during the winter and fall. We find that precipitation in the fall is significantly correlated to the longitude of the Icelandic Low and the NAO. Winter precipitation is correlated with the strength and longitude of the Icelandic Low, as well as the NAO. We show that in years of extreme high precipitation, onshore winds dominate, thereby advecting more moisture inland. In low precipitation years, winds are more westerly, approaching the stations from land. Understanding the controls of SE Greenland precipitation will help us predict how future precipitation in this key region may change in a warming climate.

The removal of sulphate from mine water by precipitation as ettringite and the utilisation of the precipitate as a sorbent for arsenate removal.

Science.gov (United States)

Tolonen, Emma-Tuulia; Hu, Tao; Rämö, Jaakko; Lassi, Ulla

2016-10-01

The aim of this research was to investigate sulphate removal from mine water by precipitation as ettringite (Ca6Al2(SO4)3(OH)12·26H2O) and the utilisation of the precipitate as a sorbent for arsenate removal. The mine water sulphate concentration was reduced by 85-90% from the initial 1400 mg/L during ettringite precipitation depending on the treatment method. The precipitation conditions were also simulated with MINEQL + software, and the computational results were compared with the experimental results. The precipitated solids were characterised with X-ray diffraction and a scanning electron microscope. The precipitated solids were tested as sorbents for arsenate removal from the model solution. The arsenic(V) model solution concentration reduced 86-96% from the initial 1.5 mg/L with a 1 g/L sorbent dosage. The effect of initial arsenate concentration on the sorption of arsenate on the precipitate was studied and Langmuir, Freundlich, and Langmuir-Freundlich sorption isotherm models were fitted to the experimental data. The maximum arsenate sorption capacity (qm = 11.2 ± 4.7 mg/g) of the precipitate was obtained from the Langmuir-Freundlich isotherm. The results indicate that the precipitate produced during sulphate removal from mine water by precipitation as ettringite could be further used as a sorbent for arsenate removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Temporal variation of extreme precipitation events in Lithuania

Directory of Open Access Journals (Sweden)

Egidijus Rimkus

2011-05-01

Full Text Available Heavy precipitation events in Lithuania for the period 1961-2008 were analysed. The spatial distribution and dynamics of precipitation extremes were investigated. Positive tendencies and in some cases statistically significant trends were determined for the whole of Lithuania. Atmospheric circulation processes were derived using Hess & Brezowski's classification of macrocirculation forms. More than one third of heavy precipitation events (37% were observed when the atmospheric circulation was zonal. The location of the central part of a cyclone (WZ weather condition subtype over Lithuania is the most common synoptic situation (27% during heavy precipitation events. Climatic projections according to outputs of the CCLM model are also presented in this research. The analysis shows that the recurrence of heavy precipitation events in the 21st century will increase significantly (by up to 22% in Lithuania.

γ' Precipitation Study of a Co-Ni-Based Alloy

Science.gov (United States)

Locq, D.; Martin, M.; Ramusat, C.; Fossard, F.; Perrut, M.

2018-05-01

A Co-Ni-based alloy strengthened by γ'-(L12) precipitates was utilized to investigate the precipitation evolution after various cooling rates and several aging conditions. In this study, the precipitate size and volume fraction have been studied via scanning electron microscopy and transmission electron microscopy. The influence of the precipitation evolution was measured via microhardness tests. The cooling rate study shows a more sluggish γ' precipitation reaction compared to that observed in a Ni-based superalloy. Following a rapid cooling rate, the application of appropriate double aging treatments allows for the increase of the γ' volume fraction as well as the control of the size and distribution of the precipitates. The highest hardness values reach those measured on supersolvus cast and wrought Ni-based superalloys. The observed γ' precipitation behavior should have implications for the production, the heat treatment, the welding, or the additive manufacturing of this new class of high-temperature materials.

Mechanisms affecting swelling in alloys with precipitates

International Nuclear Information System (INIS)

Mansur, L.K.; Haynes, M.R.; Lee, E.H.

1980-01-01

In alloys under irradiation many mechanisms exist that couple phase instability to cavity swelling. These are compounded with the more familiar mechanisms associated with point defect behavior and the evolution of microstructure. The mechanisms may be classified according to three modes of operation. Some affect cavity swelling directly by cavity-precipitate particle association, others operate indirectly by precipitate-induced changes in sinks other than cavities and finally there are mechanisms that are mediated by precipitate-induced changes in the host matrix. The physics of one mechanism of each type is developed in detail and the results compared where possible to experimental measurements. In particular, we develop the theory necessary to treat the effects on swelling of precipitation-induced changes in overall sink density; precipitation-induced changes in point defect trapping by solute depletion and creation of precipitate particle-matrix interfacial trap sites; and preciwill come from waste wood available locally requiring minimal energy for recovery and transportation to the site. The applicant is strongly considering the use of a solar preheating unit anium southward as well as to deeper dened al half-lives with experimental ones, over a range of 24 orders of magnitude was obtained. This is a strong argument that the alpha decay could be considered a fission process with very high mass asymmetry and charge density asymmetry

High-throughput computational search for strengthening precipitates in alloys

International Nuclear Information System (INIS)

Kirklin, S.; Saal, James E.; Hegde, Vinay I.; Wolverton, C.

2016-01-01

The search for high-strength alloys and precipitation hardened systems has largely been accomplished through Edisonian trial and error experimentation. Here, we present a novel strategy using high-throughput computational approaches to search for promising precipitate/alloy systems. We perform density functional theory (DFT) calculations of an extremely large space of ∼200,000 potential compounds in search of effective strengthening precipitates for a variety of different alloy matrices, e.g., Fe, Al, Mg, Ni, Co, and Ti. Our search strategy involves screening phases that are likely to produce coherent precipitates (based on small lattice mismatch) and are composed of relatively common alloying elements. When combined with the Open Quantum Materials Database (OQMD), we can computationally screen for precipitates that either have a stable two-phase equilibrium with the host matrix, or are likely to precipitate as metastable phases. Our search produces (for the structure types considered) nearly all currently known high-strength precipitates in a variety of fcc, bcc, and hcp matrices, thus giving us confidence in the strategy. In addition, we predict a number of new, currently-unknown precipitate systems that should be explored experimentally as promising high-strength alloy chemistries.

Precipitation hardening in dilute Al–Zr alloys

Directory of Open Access Journals (Sweden)

Pedro Henrique Lamarão Souza

2018-01-01

Full Text Available The aim of this study was to investigate the effect of solute content (hipoperitectic Al–0.22 wt.%Zr and hiperperitectic Al–0.32 wt.%Zr on the precipitation hardening and microstructural evolution of dilute Al–Zr alloys isothermally aged. The materials were conventionally cast in a muffle furnace, solidified in a water-cooled Cu mold and subsequently heat-treated at the temperature of 650 K (377 °C for 4, 12, 24, 100 and 400 h. Mechanical characterization was performed at room temperature, using a microhardness tester and microstructural characterization was carried out on a Transmission Electron Microscope – TEM. The observed microhardness values increased during isothermal aging, due to the precipitation of nanometer-scale Al3Zr L12 particles. Peak strength was achieved within 100 h of aging. After aging for 400 h, microhardness values presented a slight decrease for both alloys, thus indicating overaging due to the coalescence of precipitates. Microhardness values increased with solute content, due to the precipitation of a higher number density of finer precipitates. After 400 h of heat-treating, coalescence was higher for the alloy with lower solute content and, also, the presence of antiphase boundaries – APBs, planar faults associated with the L12 to D023 structural transition, were observed. Comparing theoretical calculations of the increment in strength due to precipitation strengthening with experimental results, it was observed that their values are in reasonable agreement. The Orowan dislocation looping mechanism takes place during precipitation hardening for both alloys in the peak hardness condition.

Precipitate microstructure evolution in exposed IN738LC superalloy

Energy Technology Data Exchange (ETDEWEB)

Strunz, Pavel, E-mail: strunz@ujf.cas.cz [Nuclear Physics Institute ASCR, CZ-25068 Řež near Prague (Czech Republic); Petrenec, Martin [Institute of Physics of Materials of the AS CR, Brno (Czech Republic); Gasser, Urs [Laboratory for Neutron Scattering, PSI, CH-5232 Villigen (Switzerland); Tobiáš, Jiří; Polák, Jaroslav [Institute of Physics of Materials of the AS CR, Brno (Czech Republic); Šaroun, Jan [Nuclear Physics Institute ASCR, CZ-25068 Řež near Prague (Czech Republic)

2014-03-15

Highlights: • Evolution of γ′-phase morphology in IN738LC Ni-base superalloy was examined by SANS. • In situ tests at high temperatures revealed trimodal precipitate distribution. • Formation, dissolution and (slow) kinetics of small γ′ precipitates was determined. • Equilibrium volume fraction of γ′ phase is significantly higher than 45%. • The small γ′ precipitates arise regardless the application of the mechanical load. -- Abstract: Nickel base superalloy IN738LC has been studied after low-cycle fatigue by Small Angle Neutron Scattering (SANS). Samples subjected to high-temperature low-cycle fatigue were annealed at various temperatures to change the size and the distribution of precipitates. Ex and in situ SANS and TEM studies were performed. It was found that additional precipitates are formed either during slow cooling from high temperatures or after reheating above 570 °C. Their size and distribution were evaluated. The precipitates arise regardless the application of the mechanical load. Nevertheless, these small precipitates influence low-cycle fatigue resistance. From the SANS data, it can be also deduced that the equilibrium volume fraction of γ′-precipitates at temperatures from room temperature to 825 °C is significantly higher than 45%. The kinetics of formation of small and medium-size γ′ precipitates at 700 and 800 °C was determined as well.

Kinetics of niobium carbide precipitation in ferrite

International Nuclear Information System (INIS)

Gendt, D.

2001-01-01

The aim of this study is to develop a NbC precipitation modelling in ferrite. This theoretical study is motivated by the fact it considers a ternary system and focus on the concurrence of two different diffusion mechanisms. An experimental study with TEP, SANS and Vickers micro-hardening measurements allows a description of the NbC precipitation kinetics. The mean radius of the precipitates is characterized by TEM observations. To focus on the nucleation stage, we use the Tomographic Atom Probe that analyses, at an atomistic scale, the position of the solute atoms in the matrix. A first model based on the classical nucleation theory and the diffusion-limited growth describes the precipitation of spherical precipitates. To solve the set of equations, we use a numerical algorithm that furnishes an evaluation of the precipitated fraction, the mean radius and the whole size distribution of the particles. The parameters that are the interface energy, the solubility product and the diffusion coefficients are fitted with the data available in the literature and our experimental results. It allows a satisfactory agreement as regards to the simplicity of the model. Monte Carlo simulations are used to describe the evolution of a ternary alloy Fe-Nb-C on a cubic centred rigid lattice with vacancy and interstitial mechanisms. This is realized with an atomistic description of the atoms jumps and their related frequencies. The model parameters are fitted with phase diagrams and diffusion coefficients. For the sake of simplicity, we consider that the precipitation of NbC is totally coherent and we neglect any elastic strain effect. We can observe different kinetic paths: for low supersaturations, we find an expected precipitation of NbC but for higher supersaturations, the very fast diffusivity of carbon atoms conducts to the nucleation of iron carbide particles. We establish that the occurrence of this second phenomenon depends on the vacancy arrival kinetics and can be related

Prolonged QT Syndrome and Seizure Secondary to Alkaline Earth Metal Deficiency: A Case Report

Directory of Open Access Journals (Sweden)

A. McKinney

2011-01-01

Full Text Available Introduction. Alkaline earth metal deficiency is recognized as a cause of both seizure and long QT syndrome. Their deficiency can have significant repercussions on the function of cells, tissues, and organs of the body. An understanding of the role of electrolytes allows an appreciation of the significance of depleted levels on cell function. Case Report. A 65-year-old lady was admitted with symptoms of chest discomfort, vomiting, increased stoma output, and dizziness. Two days following admission she suffered a tonic-clonic seizure. ECG review demonstrated a prolonged QTc interval, raising the possibility of an underlying Torsades de Pointes as the precipitant. This was attributed to electrolyte disturbance arising as a result of multiple aetiologies. Discussion. This paper highlights the multisystem effects of electrolyte disturbance, with emphasis upon its role in precipitating cardiac arrhythmia and neurological symptoms.

Co-precipitation synthesis and luminescence behavior of Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor: The effect of precipitant

International Nuclear Information System (INIS)

Zhang Kai; Liu Hezhou; Wu Yating; Hu Wenbin

2008-01-01

YAG:Ce precursors were co-precipitated using ammonia water and ammonium hydrogen carbonate as precipitants, respectively. Phase transition of the precursors during sintering was compared between the two precipitants. The precursors synthesized with ammonia water transformed to YAG at about 1000 deg. C via YAlO 3 phase. The precursors synthesized with ammonium hydrogen carbonate directly converted to pure YAG at about 900 deg. C. Comparing the powders produced with the two precipitants, the powders produced with ammonia hydrogen carbonate showed good dispersity. When sintered at 1600 deg. C, aggregation of the powders synthesized with the two precipitants both became severe. With increase the sintering temperature, the maximum wavelength of excitation and emission spectra of the phosphors synthesized with ammonium water hardly varied. While the maximum wavelength of excitation spectra of the phosphors synthesized with ammonium hydrogen carbonate unchanged, and the emission spectra showed red shift. Because of size effect and higher loss of cerium content, the emission intensity of phosphors prepared with ammonium hydrogen carbonate was lower than the phosphors prepared with ammonium water, when sintered at the same temperature

Inhibition of calcium phosphate precipitation under environmentally-relevant conditions

International Nuclear Information System (INIS)

Cao Xinde; Harris, Willie G.; Josan, Manohardeep S.; Nair, Vimala D.

2007-01-01

Precipitation of Ca phosphates plays an important role in controlling P activity and availability in environmental systems. The purpose of this study was to determine inhibitory effects on Ca phosphate precipitation by Mg 2+ , SO 4 2- , CO 3 2- , humic acid, oxalic acid, biogenic Si, and Si-rich soil clay commonly found in soils, sediments, and waste streams. Precipitation rates were determined by measuring decrease of P concentration in solutions during the first 60 min; and precipitated solid phases identified using X-ray diffraction and electron microscopy. Poorly-crystalline hydroxyapatite (HAP: Ca 5 (PO 4 ) 3 OH) formed in control solutions over the experiment period of 24 h, following a second-order dependence on P concentration. Humic acid and Mg 2+ significantly inhibited formation of HAP, allowing formation of a more soluble amorphous Ca phosphate phase (ACP), and thus reducing the precipitation rate constants by 94-96%. Inhibition caused by Mg 2+ results from its incorporation into Ca phosphate precipitates, preventing formation of a well-crystalline phase. Humic acid likely suppressed Ca phosphate precipitation by adsorbing onto the newly-formed nuclei. Presence of oxalic acid resulted in almost complete inhibition of HAP precipitation due to preemptive Ca-oxalate formation. Carbonate substituted for phosphate, decreasing the crystallinity of HAP and thus reducing precipitation rate constant by 44%. Sulfate and Si-rich solids had less impact on formation of HAP; while they reduced precipitation in the early stage, they did not differ from the control after 24 h. Results indicate that components (e.g., Mg 2+ , humic acid) producing relatively soluble ACP are more likely to reduce P stability and precipitation rate of Ca phosphate in soils and sediments than are components (e.g., SO 4 2- , Si) that have less effect on the crystallinity

Acid precipitation in Europe and Asia

International Nuclear Information System (INIS)

Angell, Valter

2000-01-01

The article surveys acid precipitation problems in the region, discusses the sources, the pollutant composition and distribution, the work with the RAINS models as well as the organisation of and the results of joint incentives in the region. The acidification problems in China and some of the Norwegian participation efforts are reviewed. The author points out that much of the acidic precipitation and the environmental problems in Eurasia are due to the use of coal rich in sulphur, that the energy and environmental policies differs throughout the region because of differences in ecology and development levels and that Asia is far more heterogeneous than Europe as to the conditions for co-ordinated efforts against acid precipitation. The differences in economy, geopolitical situation, environmental policies etc. are larger than in Europe and a considerable international effort will be required in order to succeed. Should the regional model RAINS-Asia be used as basis for further co-ordinated efforts on acid precipitation thorough evaluations on costs and advantages are needed. The conditions and need for modelling as basis for international agreements between Asiatic countries are not the same as in Europe. Finally international development organisations have and will continue to play an important part in the work for reducing acid precipitation in Asia. The Asiatic countries may also greatly benefit in the battle against acid precipitation from the experiences of the industrialised countries. However, Asiatic countries will have to meet the major costs of emission reduction themselves. The main question is what emphasis will be put on the long term environmental profits and on the need for rapid economic growth of materially impoverished people. Other development directions than those used by the industrialised countries, seems to be needed

Addison's disease in a patient with hypothyroidism: autoimmune polyglandular syndrome type 2.

Science.gov (United States)

Bain, Anna; Stewart, Munro; Mwamure, Peter; Nirmalaraj, Kingsley

2015-08-03

A 57-year-old Caucasian woman with known autoimmune hypothyroidism diagnosed in 2006 presented to hospital with flu-like symptoms and circulatory collapse. She reported weight loss and gradual increase in her skin pigmentation over a 1-year period. Aggressive fluid resuscitation was instituted. Hormonal tests showed primary adrenal insufficiency. Appropriate steroid replacement was started with rapid clinical response. Subsequent antibody tests confirmed the diagnosis of autoimmune polyglandular type 2 (Schmidt's) syndrome. The adrenal crisis had been precipitated by influenza virus type B infection. 2015 BMJ Publishing Group Ltd.

Discontinuous precipitation in copper base alloys

Indian Academy of Sciences (India)

Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show DP while others do not. In this paper the misfit strain parameter, , has been calculated and predicted that if 100 > ± 0.1, DP is ...

Meteorological features associated with unprecedented precipitation ...

Indian Academy of Sciences (India)

Unprecedented precipitation along with heavy falls occurred over many parts of India from 28th February to 2nd March 2015. Many of the stations of northwest and central India received an all time high 24 hr cumulative precipitation of March during this period. Even the national capital, New Delhi, broke all the previous ...

Is southwestern China experiencing more frequent precipitation extremes?

International Nuclear Information System (INIS)

Liu, Meixian; Xu, Xianli; Wang, Kelin; Sun, Alexander Y; Liu, Wen; Zhang, Xiaoyan

2014-01-01

Climate extremes have and will continue to cause severe damages to buildings and natural environments around the world. A full knowledge of the probability of the climate extremes is important for the management and mitigation of natural hazards. Based on Mann–Kendall trend test and copulas, this study investigated the characteristics of precipitation extremes as well as their implications in southwestern China (Yunnan, Guangxi and Guizhou Province), through analyzing the changing trends and probabilistic characteristics of six indices, including the consecutive dry days, consecutive wet days, annual total wet day precipitation, heavy precipitation days (R25), max 5 day precipitation amount (Rx5) and the rainy days (RDs). Results showed that the study area had generally become drier (regional mean annual precipitation decreased by 11.4 mm per decade) and experienced enhanced precipitation extremes in the past 60 years. Relatively higher risk of drought in Yuanan and flood in Guangxi was observed, respectively. However, the changing trends of the precipitation extremes were not spatially uniform: increasing risk of extreme wet events for Guangxi and Guizhou, and increasing probability of concurrent extreme wet and dry events for Yunnan. Meanwhile, trend analyses of the 10 year return levels of the selected indices implied that the severity of droughts decreased in Yunnan but increased significantly in Guangxi and Guizhou, and the severity of floods increased in Yunnan and Guangxi in the past decades. Hence, the policy-makers need to be aware of the different characterizations and the spatial heterogeneity of the precipitation extremes. (letters)

Factors controlling stable isotope composition of European precipitation

International Nuclear Information System (INIS)

Rozanski, K.; Sonntag, C.; Muennich, K.O.

1982-01-01

The seasonal and spatial variations of stable isotope ratios in present day European precipitation are simulated with a simple multibox model of the mean west-east horizontal transport of the atmospheric water vapour across the European continent. Isotope fractionation during the formation of precipitation leads to an increasing depletion of heavy isotopes in the residual air moisture as it moves towards the centre of the continent. This isotopic depletion is partly compensated, particularly in summer, by evapotranspiration, which is assumed to transfer soil water into the atmosphere without isotope fractionation. The model estimates are based on horizontal water vapour flux data, varying seasonally between 88 and 130 kg m -1 s -1 for the Atlantic coast region, and on the monthly precipitation, evapotranspiration and surface air temperature data available for various locations in Europe. Both continental and seasonal temperature effects observed in the stable isotope composition of European precipitation are fairly well reproduced by the model. The calculations show that the isotopic composition of local precipitation is primarily controlled by regional scale processes, i.e. by the water vapour transport patterns into the continent, and by the average precipitation-evapotranspiration history of the air masses precipitating at a given place. Local parameters such as the surface and/or cloud base temperature or the amount of precipitation modify the isotope ratios only slightly. Implications of the model predictions for the interpretation of stable isotope ratios in earlier periods as they are preserved in ice cores and in groundwater are also discussed. (Auth.)

Marfan syndrome masked by Down syndrome?

NARCIS (Netherlands)

Vis, J.C.; Engelen, K. van; Timmermans, J.; Hamel, B.C.J.; Mulder, B.J.

2009-01-01

Down syndrome is the most common chromosomal abnormality. A simultaneous occurrence with Marfan syndrome is extremely rare. We present a case of a 28-year-old female with Down syndrome and a mutation in the fibrillin-1 gene. The patient showed strikingly few manifestations of Marfan syndrome.

Precipitation measurement and derivation of precipitation inclination in a windy mountainous area in northern Costa Rica. Scientific Briefing.

NARCIS (Netherlands)

Frumau, K.F.A.; Bruijnzeel, L.A.; Tobón, C.

2011-01-01

Over small-scale topography in windy areas, precipitation tends to be redistributed by wind through the modification of precipitation inclination. The latter is often derived from wind speed and conventional rain gauge records by application of relations-derived mainly for convective rainfall

Exploring the mechanisms of vehicle front-end shape on pedestrian head injuries caused by ground impact.

Science.gov (United States)

Yin, Sha; Li, Jiani; Xu, Jun

2017-09-01

In pedestrian-vehicle accidents, pedestrians typically suffer from secondary impact with the ground after the primary contact with vehicles. However, information about the fundamental mechanism of pedestrian head injury from ground impact remains minimal, thereby hindering further improvement in pedestrian safety. This study addresses this issue by using multi-body modeling and computation to investigate the influence of vehicle front-end shape on pedestrian safety. Accordingly, a simulation matrix is constructed to vary bonnet leading-edge height, bonnet length, bonnet angle, and windshield angle. Subsequently, a set of 315 pedestrian-vehicle crash simulations are conducted using the multi-body simulation software MADYMO. Three vehicle velocities, i.e., 20, 30, and 40km/h, are set as the scenarios. Results show that the top governing factor is bonnet leading-edge height. The posture and head injury at the instant of head ground impact vary dramatically with increasing height because of the significant rise of the body bending point and the movement of the collision point. The bonnet angle is the second dominant factor that affects head-ground injury, followed by bonnet length and windshield angle. The results may elucidate one of the critical barriers to understanding head injury caused by ground impact and provide a solid theoretical guideline for considering pedestrian safety in vehicle design. Copyright © 2017 Elsevier Ltd. All rights reserved.

Uranium peroxide precipitate drying temperature relationships

Energy Technology Data Exchange (ETDEWEB)

Rodgers, C.; Dyck, B., E-mail: chick_rodgers@cameco.com [Cameco Corp., Saskatoon, SK (Canada)

2010-07-01

Cameco Corporation is in the process of revitalizing the mill at its Key Lake operation in northern Saskatchewan. The current Key Lake process employs ammonia stripping and ammonia precipitation. As part of the revitalization, the company is considering installing strong acid stripping in solvent extraction as used at its Rabbit Lake operation. This change would lead to using hydrogen peroxide for uranium precipitation. As part of the process evaluation, tests were carried out to study how changes in the temperature of an indirect fired dryer affected the properties of uranium peroxide [yellowcake] precipitate. This paper discusses the results of the test work, including the relationships between drying temperature and the following: (author)

Precipitation Reconstruction (PREC)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The PREC data set is an analysis of monthly precipitation constructed on a 2.5(o)lat/lon grid over the global for the period from 1948 to the present. The land...

Improving Global Precipitation Product Access at the GES DISC

Science.gov (United States)

Liu, Z.; Vollmer, B.; Savtchenko, A.; Ostrenga, D.; DeShong, B.; Fang, F.; Albayrak, R,; Sherman, E.; Greene, M.; Li, A.;

Investigation of Neptunium Precipitator Cleanout Options

International Nuclear Information System (INIS)

Hill, B.C.

2003-01-01

Oxalate precipitation followed by filtration is used to prepare plutonium oxalate. Historically, plutonium oxalate has tended to accumulate in the precipitation tanks. These solids are periodically removed by flushing with concentrated (64 percent) nitric acid. The same precipitation tanks will now be used in the processing of neptunium. Literature values indicate that neptunium oxalate may not be as soluble as plutonium oxalate in nitric acid. Although a wide variety of options is available to improve neptunium oxalate solubility for precipitator flushing, most of these options are not practical for use. Many of these options require the use of incompatible or difficult to handle chemicals. Other options would require expensive equipment modifications or are likely to lead to product contamination. Based on review of literature and experimental results, the two best options for flushing the precipitator are (1) 64 percent nitric acid and (2) addition of sodium permanganate follow ed by sodium nitrite. Nitric acid is the easiest option to implement. It is already used in the facility and will not lead to product contamination. Experimental results indicate that neptunium oxalate can be dissolved in concentrated nitric acid (64 percent) at 60 degree C to a concentration of 2.6 to 5.6 grams of Np/liter after at least three hours of heating. A lower concentration (1.1 grams of Np/liter) was measured at 60 degree C after less than two hours of heating. These concentrations are acceptable for flushing if precipitator holdup is low (approximately 100-250 grams), but a second method is required for effective flushing if precipitator holdup is high (approximately 2 kilograms). The most effective method for obtaining higher neptunium concentrations is the use of sodium permanganate followed by the addition of sodium nitrite. There is concern that residual manganese from these flushes could impact product purity. Gas generation during permanganate addition is also a concern

River flooding due to intense precipitation

International Nuclear Information System (INIS)

Lin, James C.

2014-01-01

River stage can rise and cause site flooding due to local intense precipitation (LIP), dam failures, snow melt in conjunction with precipitation or dam failures, etc. As part of the re-evaluation of the design basis as well as the PRA analysis of other external events, the likelihood and consequence of river flooding leading to the site flooding need to be examined more rigorously. To evaluate the effects of intense precipitation on site structures, the site watershed hydrology and pond storage are calculated. To determine if river flooding can cause damage to risk-significant systems, structures, and components (SSC), water surface elevations are analyzed. Typically, the amount and rate of the input water is determined first. For intense precipitation, the fraction of the rainfall in the watershed drainage area not infiltrated into the ground is collected in the river and contributes to the rise of river water elevation. For design basis analysis, the Probable Maximum Flood (PMF) is evaluated using the Probable Maximum Precipitation (PMP) based on the site topography/configuration. The peak runoff flow rate and water surface elevations resulting from the precipitation induced flooding can then be estimated. The runoff flow hydrograph and peak discharge flows can be developed using the synthetic hydrograph method. The standard step method can then be used to determine the water surface elevations along the river channel. Thus, the flood water from the local intense precipitation storm and excess runoff from the nearby river can be evaluated to calculate the water surface elevations, which can be compared with the station grade floor elevation to determine the effects of site flooding on risk-significant SSCs. The analysis needs to consider any possible diversion flow and the effects of changes to the site configurations. Typically, the analysis is performed based on conservative peak rainfall intensity and the assumptions of failure of the site drainage facilities

Precipitation diagram of calcium carbonate polymorphs: its construction and significance

International Nuclear Information System (INIS)

Kawano, Jun; Shimobayashi, Norimasa; Miyake, Akira; Kitamura, Masao

2009-01-01

In order to interpret the formation mechanism of calcium carbonate polymorphs, we propose and construct a new 'precipitation diagram', which has two variables: the driving force for nucleation and temperature. The precipitation experiments were carried out by mixing calcium chloride and sodium carbonate aqueous solutions. As a result, a calcite-vaterite co-precipitation zone, a vaterite precipitation zone, a vaterite-aragonite co-precipitation zone and an aragonite precipitation zone can be defined. Theoretical considerations suggest that the steady state nucleation theory can explain well the appearance of these four zones, and the first-order importance of the temperature dependency of surface free energy in the nucleation of aragonite. Furthermore, the addition of an impurity will likely result in the change of these energies, and this precipitation diagram gives a new basis for interpreting the nature of the polymorphs precipitated in both inorganic and biological environments.

Irritable bowel syndrome: role of food in pathogenesis and management.

LENUS (Irish Health Repository)

Morcos, Ashraf

2009-11-01

Patients with the irritable bowel syndrome (IBS) commonly report the precipitation of symptoms on food ingestion. Though the role of dietary constituents in IBS has not been extensively studied, food could contribute to symptom onset or even the causation of IBS through a number of mechanisms. First, the physiological response of the intestine to food ingestion could precipitate symptoms in predisposed individuals; second, there is some evidence that allergy or intolerance to a particular food can produce IBS-like symptoms, third, certain foods may alter the composition of the luminal milieu, either directly or indirectly through effects on bacterial metabolism, and thus induce symptoms and, finally, IBS may develop following exposure to food-borne pathogens. Anticipatory, psychological factors generated by previous negative experiences with food ingestion or other factors may also contribute though their contribution has been scarcely quantified. Not surprisingly, there is considerable interest in the potential roles of diet and food supplements in the therapy of IBS; for the most part, the evidence base for such recommendations remains slim though certain probiotics show considerable promise.

Strong increase in convective precipitation in response to higher temperatures

DEFF Research Database (Denmark)

Berg, P.; Moseley, C.; Härter, Jan Olaf Mirko

2013-01-01

Precipitation changes can affect society more directly than variations in most other meteorological observables, but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly...... at higher temperature, faster than the rate of increase in the atmosphere's water-holding capacity, termed the Clausius-Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in stratiform precipitation (such as large-scale frontal precipitation......) as a cause for this increase , but the relative contributions of these two types of precipitation have been difficult to disentangle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic observations and temperature records, and separate convective...

The developmental trajectory of disruptive behavior in Down syndrome, fragile X syndrome, Prader-Willi syndrome and Williams syndrome.

Science.gov (United States)

Rice, Lauren J; Gray, Kylie M; Howlin, Patricia; Taffe, John; Tonge, Bruce J; Einfeld, Stewart L

2015-06-01

The aim of this study was to investigate the developmental trajectories of verbal aggression, physical aggression, and temper tantrums in four genetic syndrome groups. Participants were part of the Australian Child to Adult Development Study (ACAD), which collected information from a cohort of individuals with an intellectual disability at five time points over 18 years. Data were examined from a total of 248 people with one of the four following syndromes: Down syndrome, Fragile X syndrome, Prader-Willi syndrome, or Williams syndrome. Changes in behaviors were measured using validated items from the Developmental Behavior Checklist (DBC). The results indicate that, while verbal aggression shows no evidence of diminishing with age, physical aggression, and temper tantrums decline with age before 19 years for people with Down syndrome, Fragile X syndrome, and William syndrome; and after 19 years for people with Prader-Willi syndrome. These findings offer a somewhat more optimistic outlook for people with an intellectual disability than has previously been suggested. Research is needed to investigate the mechanisms predisposing people with PWS to persistence of temper tantrums and physical aggression into adulthood. © 2015 Wiley Periodicals, Inc.

A Portable Burn Pan for the Disposal of Excess Propellants

Science.gov (United States)

2015-11-01

was inspected to ensure completion of the process. When the handles on the bonnet were cool enough to touch , the bonnet was removed, the ash... problems were encountered by shorter individuals removing the bonnet from the base of the pan. This and the weight issue will be addressed in a final...Analytes Only charges 6 and 7 were available for the tests. Using component data from MIDAS , charge 6 weighs 255 g, 250 g of which is M1 single base

Catastrophic antiphospholipid syndrome: a clinical review.

Science.gov (United States)

Nayer, Ali; Ortega, Luis M

2014-01-01

Catastrophic antiphospholipid syndrome (CAPS) is a rare life-threatening autoimmune disease characterized by disseminated intravascular thrombosis resulting in multiorgan failure. Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO) and Web of Science have been searched. CAPS is due to antiphospholipid antibodies directed against a heterogeneous group of proteins that are associated with phospholipids. These autoantibodies activate endothelial cells, platelets, and immune cells, thereby promoting a proinflammatory and prothrombotic phenotype. Furthermore, antiphospholipid antibodies inhibit anticoagulants, impair fibrinolysis, and activate complements. Although CAPS can affect a variety of organs and tissues, the kidneys, lungs, central nervous system, heart, skin, liver, and gastrointestinal tract are most commonly affected. The systemic inflammatory response syndrome, likely to extensive tissue damage, accompanies CAPS. The most frequent renal manifestations are hypertension, proteinuria, hematuria, and acute renal failure.In the majority of patients with CAPS, a precipitating factor such as infection, surgery, or medication can be identified. Antiphospholipid antibodies such as lupus anticoagulant and antibodies against cardiolipin, β2-glycoprotein I, and prothrombin are serological hallmark of CAPS. Laboratory tests often reveal antinuclear antibodies, thrombocytopenia, and anemia. Despite widespread intravascular coagulation, blood films reveal only a small number of schistocytes. In addition, severe thrombocytopenia is uncommon. Histologically, CAPS is characterized by acute thrombotic microangiopathy. CAPS must be distinguished from other forms of thrombotic microangiopathies such as hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, and heparin-induced thrombocyt openia. CAPS is associated with high morbidity and mortality. Therefore, an aggressive multidisciplinary

Maximizing recovery of water-soluble proteins through acetone precipitation.

Science.gov (United States)

Crowell, Andrew M J; Wall, Mark J; Doucette, Alan A

2013-09-24

Solvent precipitation is commonly used to purify protein samples, as seen with the removal of sodium dodecyl sulfate through acetone precipitation. However, in its current practice, protein loss is believed to be an inevitable consequence of acetone precipitation. We herein provide an in depth characterization of protein recovery through acetone precipitation. In 80% acetone, the precipitation efficiency for six of 10 protein standards was poor (ca. ≤15%). Poor recovery was also observed for proteome extracts, including bacterial and mammalian cells. As shown in this work, increasing the ionic strength of the solution dramatically improves the precipitation efficiency of individual proteins, and proteome mixtures (ca. 80-100% yield). This is obtained by including 1-30 mM NaCl, together with acetone (50-80%) which maximizes protein precipitation efficiency. The amount of salt required to restore the recovery correlates with the amount of protein in the sample, as well as the intrinsic protein charge, and the dielectric strength of the solution. This synergistic approach to protein precipitation in acetone with salt is consistent with a model of ion pairing in organic solvent, and establishes an improved method to recover proteins and proteome mixtures in high yield. Copyright © 2013 Elsevier B.V. All rights reserved.

California Wintertime Precipitation in Regional and Global Climate Models

Energy Technology Data Exchange (ETDEWEB)

Caldwell, P M

2009-04-27

In this paper, wintertime precipitation from a variety of observational datasets, regional climate models (RCMs), and general circulation models (GCMs) is averaged over the state of California (CA) and compared. Several averaging methodologies are considered and all are found to give similar values when model grid spacing is less than 3{sup o}. This suggests that CA is a reasonable size for regional intercomparisons using modern GCMs. Results show that reanalysis-forced RCMs tend to significantly overpredict CA precipitation. This appears to be due mainly to overprediction of extreme events; RCM precipitation frequency is generally underpredicted. Overprediction is also reflected in wintertime precipitation variability, which tends to be too high for RCMs on both daily and interannual scales. Wintertime precipitation in most (but not all) GCMs is underestimated. This is in contrast to previous studies based on global blended gauge/satellite observations which are shown here to underestimate precipitation relative to higher-resolution gauge-only datasets. Several GCMs provide reasonable daily precipitation distributions, a trait which doesn't seem tied to model resolution. GCM daily and interannual variability is generally underpredicted.

Effect of creep-aging on precipitates of 7075 aluminum alloy

Energy Technology Data Exchange (ETDEWEB)

Lin, Y.C., E-mail: yclin@csu.edu.cn [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083 (China); State Key Laboratory of Material Processing and Die and Mould Technology, Wuhan 430074 (China); Jiang, Yu-Qiang; Chen, Xiao-Min; Wen, Dong-Xu [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083 (China); Zhou, Hua-Min [State Key Laboratory of Material Processing and Die and Mould Technology, Wuhan 430074 (China)

2013-12-20

The creep-aging behaviors of 7075 aluminum alloy are studied by uniaxial tensile creep experiments under elevated temperatures. The effects of creep-aging temperature and applied stress on the precipitates of 7075-T651 aluminum alloy are investigated using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Results show that (1) coarse insoluble precipitates (Al{sub 7}Cu{sub 2}Fe and Mg{sub 2}Si) and intermediate precipitates (Al{sub 18}Mg{sub 3}Cr{sub 2} and Al{sub 3}Zr) are found in the aluminum matrix, and the effects of creep-aging treatment on these precipitates are not obvious; (2) the main aging precipitates are η′ and η phases, and the amount of aging precipitates increase with the increase of creep-aging temperature and applied stress; (3) with the increase of creep-aging temperature and applied stress, the precipitates are discontinuously distributed on the grain boundary, and the width of precipitate free zone increases with the increase of creep-aging temperature and applied stress and (4) compared with the microstructure in the traditional stress-free aged sample, the creep-aging process can refine the precipitates and narrow the width of the precipitate free zone.

Hamartomatous polyposis syndromes

DEFF Research Database (Denmark)

Jelsig, Anne Marie; Qvist, Niels; Brusgaard, Klaus

2014-01-01

Hamartomatous Polyposis Syndromes (HPS) are genetic syndromes, which include Peutz-Jeghers syndrome, Juvenile polyposis syndrome, PTEN hamartoma tumour syndrome (Cowden Syndrom, Bannayan-Riley-Ruvalcaba and Proteus Syndrome) as well as hereditary mixed polyposis syndrome. Other syndromes such as ......Hamartomatous Polyposis Syndromes (HPS) are genetic syndromes, which include Peutz-Jeghers syndrome, Juvenile polyposis syndrome, PTEN hamartoma tumour syndrome (Cowden Syndrom, Bannayan-Riley-Ruvalcaba and Proteus Syndrome) as well as hereditary mixed polyposis syndrome. Other syndromes...

GRAIN-BOUNDARY PRECIPITATION UNDER IRRADIATION IN DILUTE BINARY ALLOYS

Institute of Scientific and Technical Information of China (English)

S.H. Song; Z.X. Yuan; J. Liu; R.G.Faulkner

2003-01-01

Irradiation-induced grain boundary segregation of solute atoms frequently bring about grain boundary precipitation of a second phase because of its making the solubility limit of the solute surpassed at grain boundaries. Until now the kinetic models for irradiation-induced grain boundary precipitation have been sparse. For this reason, we have theoretically treated grain boundary precipitation under irradiation in dilute binary alloys. Predictions ofγ'-Ni3Si precipitation at grain boundaries ave made for a dilute Ni-Si alloy subjected to irradiation. It is demonstrated that grain boundary silicon segregation under irradiation may lead to grain boundaryγ'-Ni3 Si precipitation over a certain temperature range.

Precipitates/Salts Model Sensitivity Calculation

Energy Technology Data Exchange (ETDEWEB)

P. Mariner

2001-12-20

The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation on potential seepage waters within a potential repository drift. This work is developed and documented using procedure AP-3.12Q, ''Calculations'', in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The specific objective of this calculation is to examine the sensitivity and uncertainties of the Precipitates/Salts model. The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b). The calculation in the current document examines the effects of starting water composition, mineral suppressions, and the fugacity of carbon dioxide (CO{sub 2}) on the chemical evolution of water in the drift.

Heating-insensitive scale increase caused by convective precipitation

Science.gov (United States)

Haerter, Jan; Moseley, Christopher; Berg, Peter

2017-04-01

The origin of intense convective extremes and their unusual temperature dependence has recently challenged traditional thermodynamic arguments, based on the Clausius-Clapeyron relation. In a sequence of studies (Lenderink and v. Mejgaard, Nat Geosc, 2008; Berg, Haerter, Moseley, Nat Geosc, 2013; and Moseley, Hohenegger, Berg, Haerter, Nat Geosc, 2016) the argument of convective-type precipitation overcoming the 7%/K increase in extremes by dynamical, rather than thermodynamic, processes has been promoted. How can the role of dynamical processes be approached for precipitating convective cloud? One-phase, non-precipitating Rayleigh-Bénard convection is a classical problem in complex systems science. When a fluid between two horizontal plates is sufficiently heated from below, convective rolls spontaneously form. In shallow, non-precipitating atmospheric convection, rolls are also known to form under specific conditions, with horizontal scales roughly proportional to the boundary layer height. Here we explore within idealized large-eddy simulations, how the scale of convection is modified, when precipitation sets in and intensifies in the course of diurnal solar heating. Before onset of precipitation, Bénard cells with relatively constant diameter form, roughly on the scale of the atmospheric boundary layer. We find that the onset of precipitation then signals an approximately linear (in time) increase in horizontal scale. This scale increase progresses at a speed which is rather insensitive to changes in surface temperature or changes in the rate at which boundary conditions change, hinting at spatial characteristics, rather than temperature, as a possible control on spatial scales of convection. When exploring the depth of spatial correlations, we find that precipitation onset causes a sudden disruption of order and a subsequent complete disintegration of organization —until precipitation eventually ceases. Returning to the initial question of convective

Inorganic nitrogen in precipitation and atmospheric sediments

Energy Technology Data Exchange (ETDEWEB)

Matheson, D H

1951-01-01

In an investigation covering 18 months, daily determinations were made of the inorganic nitrogen contained in precipitation and atmospheric sediments collected at Hamilton, Ont. The nitrogen fall for the whole period averaged 5.8 lb. N per acre per year. Sixty-one per cent of the total nitrogen was collected on 25% of the days when precipitation occurred. The balance, occurring on days without precipitation, is attributable solely to the sedimentation of dust. Ammonia nitrogen averaged 56% of the total, but the proportion for individual days varied widely.

Oxygen-18 in present-day precipitation on the Tibetan Plateau

Institute of Scientific and Technical Information of China (English)

章新平; 姚檀栋; 中尾正义

2001-01-01

The temporal and spatial variations of the δ18O in precipitation on the Tibetan Plateau are analyzed. There is no temperature effect in the southern Tibetan Plateau. Amount effect has been observed at Lhasa station. However, the seasonal variations of the δ18O in precipitation are different from that of precipitation intensity, showing that the precipitation intensity is not a main controlling factor on the stable isotopic compositions in precipitation in the southern Tibetan Plateau. There is notable temperature effect in the middle and northern Tibetan Plateau. The seasonal variations of the δ18O in precipitation are almost consistent with those of air temperature there, indicating that temperature is a main factor controlling the stable isotopic variations in precipitation. A meridional cross-section shows that a notable depletion of the stable isotopic ratio in precipitation takes place in the Himalayas due to very strong rainout of vapor as it rises over the Himalayas, then the δ18O remains basi

Decadal changes in extreme daily precipitation in Greece

Directory of Open Access Journals (Sweden)

P. T. Nastos

2008-04-01

Full Text Available The changes in daily precipitation totals in Greece, during the 45-year period (1957–2001 are examined. The precipitation datasets concern daily totals recorded at 21 surface meteorological stations of the Hellenic National Meteorological Service, which are uniformly distributed over the Greek region. First and foremost, the application of Factor Analysis resulted in grouping the meteorological stations with similar variation in time. The main sub groups represent the northern, southern, western, eastern and central regions of Greece with common precipitation characteristics. For representative stations of the extracted sub groups we estimated the trends and the time variability for the number of days (% exceeding 30 mm (equal to the 95% percentile of daily precipitation for eastern and western regions and equal to the 97.5% percentile for the rest of the country and 50 mm which is the threshold for very extreme and rare events. Furthermore, the scale and shape parameters of the well fitted gamma distribution to the daily precipitation data with respect to the whole examined period and to the 10-year sub periods reveal the changes in the intensity of the precipitation.

An Ultra-high Resolution Synthetic Precipitation Data for Ungauged Sites

Science.gov (United States)

Kim, Hong-Joong; Choi, Kyung-Min; Oh, Jai-Ho

2018-05-01

Despite the enormous damage caused by record heavy rainfall, the amount of precipitation in areas without observation points cannot be known precisely. One way to overcome these difficulties is to estimate meteorological data at ungauged sites. In this study, we have used observation data over Seoul city to calculate high-resolution (250-meter resolution) synthetic precipitation over a 10-year (2005-2014) period. Furthermore, three cases are analyzed by evaluating the rainfall intensity and performing statistical analysis over the 10-year period. In the case where the typhoon "Meari" passed to the west coast during 28-30 June 2011, the Pearson correlation coefficient was 0.93 for seven validation points, which implies that the temporal correlation between the observed precipitation and synthetic precipitation was very good. It can be confirmed that the time series of observation and synthetic precipitation in the period almost completely matches the observed rainfall. On June 28-29, 2011, the estimation of 10 to 30 mm h-1 of continuous strong precipitation was correct. In addition, it is shown that the synthetic precipitation closely follows the observed precipitation for all three cases. Statistical analysis of 10 years of data reveals a very high correlation coefficient between synthetic precipitation and observed rainfall (0.86). Thus, synthetic precipitation data show good agreement with the observations. Therefore, the 250-m resolution synthetic precipitation amount calculated in this study is useful as basic data in weather applications, such as urban flood detection.

Precipitation evolution and kinetics in a magnesium-neodymium-zinc alloy

International Nuclear Information System (INIS)

Sanaty-Zadeh, A.; Xia, X.; Luo, A.A.; Stone, D.S.

2014-01-01

Highlights: • Precipitation sequence and kinetics in Mg–3Nd–0.2Zn wt.% alloy were studied. • Lower amount of zinc than 0.5 wt.% does not change the sequence of precipitation. • A new orientation with respect to the matrix was detected for β″ precipitates. • β″ Precipitates contribute to the age hardening of the alloy. • Quenched-in vacancies play an important role in early stage of precipitation. -- Abstract: In this research, the precipitation sequence investigation and phase identification in Mg–3Nd–0.2Zn–0.46Zr (wt.%) system were performed using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) techniques. The results showed the precipitation sequence to be: Super saturated solid solution (SSSS) → Clustering of atoms/short range ordering → β″ → β′ → β which shows that low zinc content (less than 0.5 %wt) does not influence the precipitation sequence. TEM studies revealed that in addition to prismatic planes, β′′ precipitates lie on pyramidal planes in Mg matrix, which has not been reported previously in this system. Further investigation using TEM and aging experiments showed that these precipitates are responsible for the age hardening of the alloy. Furthermore, the kinetic studies showed that quenched-in vacancies play an important role in the early stage of precipitation and formation of β′′ while formation of β′ is dominantly diffusion controlled process and quenched-in vacancies are no longer effective

Inducing mineral precipitation in groundwater by addition of phosphate

Directory of Open Access Journals (Sweden)

Hartmann Thomas

2011-10-01

Full Text Available Abstract Background Induced precipitation of phosphate minerals to scavenge trace elements from groundwater is a potential remediation approach for contaminated aquifers. The success of engineered precipitation schemes depends on the particular phases generated, their rates of formation, and their long term stability. The purpose of this study was to examine the precipitation of calcium phosphate minerals under conditions representative of a natural groundwater. Because microorganisms are present in groundwater, and because some proposed schemes for phosphate mineral precipitation rely on stimulation of native microbial populations, we also tested the effect of bacterial cells (initial densities of 105 and 107 mL-1 added to the precipitation medium. In addition, we tested the effect of a trace mixture of propionic, isovaleric, formic and butyric acids (total concentration 0.035 mM. Results The general progression of mineral precipitation was similar under all of the study conditions, with initial formation of amorphous calcium phosphate, and transformation to poorly crystalline hydroxylapatite (HAP within one week. The presence of the bacterial cells appeared to delay precipitation, although by the end of the experiments the overall extent of precipitation was similar for all treatments. The stoichiometry of the final precipitates as well as Rietveld structure refinement using x-ray diffraction data indicated that the presence of organic acids and bacterial cells resulted in an increasing a and decreasing c lattice parameter, with the higher concentration of cells resulting in the greatest distortion. Uptake of Sr into the solids was decreased in the treatments with cells and organic acids, compared to the control. Conclusions Our results suggest that the minerals formed initially during an engineered precipitation application for trace element sequestration may not be the ones that control long-term immobilization of the contaminants. In

Merging Satellite Precipitation Products for Improved Streamflow Simulations

Science.gov (United States)

Maggioni, V.; Massari, C.; Barbetta, S.; Camici, S.; Brocca, L.

2017-12-01

Accurate quantitative precipitation estimation is of great importance for water resources management, agricultural planning and forecasting and monitoring of natural hazards such as flash floods and landslides. In situ observations are limited around the Earth, especially in remote areas (e.g., complex terrain, dense vegetation), but currently available satellite precipitation products are able to provide global precipitation estimates with an accuracy that depends upon many factors (e.g., type of storms, temporal sampling, season, etc.). The recent SM2RAIN approach proposes to estimate rainfall by using satellite soil moisture observations. As opposed to traditional satellite precipitation methods, which sense cloud properties to retrieve instantaneous estimates, this new bottom-up approach makes use of two consecutive soil moisture measurements for obtaining an estimate of the fallen precipitation within the interval between two satellite overpasses. As a result, the nature of the measurement is different and complementary to the one of classical precipitation products and could provide a different valid perspective to substitute or improve current rainfall estimates. Therefore, we propose to merge SM2RAIN and the widely used TMPA 3B42RT product across Italy for a 6-year period (2010-2015) at daily/0.25deg temporal/spatial scale. Two conceptually different merging techniques are compared to each other and evaluated in terms of different statistical metrics, including hit bias, threat score, false alarm rates, and missed rainfall volumes. The first is based on the maximization of the temporal correlation with a reference dataset, while the second is based on a Bayesian approach, which provides a probabilistic satellite precipitation estimate derived from the joint probability distribution of observations and satellite estimates. The merged precipitation products show a better performance with respect to the parental satellite-based products in terms of categorical

Supercritical antisolvent co-precipitation of rifampicin and ethyl cellulose.

Science.gov (United States)

Djerafi, Rania; Swanepoel, Andri; Crampon, Christelle; Kalombo, Lonji; Labuschagne, Philip; Badens, Elisabeth; Masmoudi, Yasmine

2017-05-01

Rifampicin-loaded submicron-sized particles were prepared through supercritical anti-solvent process using ethyl cellulose as polymeric encapsulating excipient. Ethyl acetate and a mixture of ethyl acetate/dimethyl sulfoxide (70/30 and 85/15) were used as solvents for both drug and polymeric excipient. When ethyl acetate was used, rifampicin was crystallized separately without being embedded within the ethyl cellulose matrix while by using the ethyl acetate/dimethyl sulfoxide mixture, reduced crystallinity of the active ingredient was observed and a simultaneous precipitation of ethyl cellulose and drug was achieved. The effect of solvent/CO 2 molar ratio and polymer/drug mass ratio on the co-precipitates morphology and drug loading was investigated. Using the solvent mixture, co-precipitates with particle sizes ranging between 190 and 230nm were obtained with drug loading and drug precipitation yield from respectively 8.5 to 38.5 and 42.4 to 77.2% when decreasing the ethyl cellulose/rifampicin ratio. Results show that the solvent nature and the initial drug concentrations affect morphology and drug precipitation yield of the formulations. In vitro dissolution studies revealed that the release profile of rifampicin was sustained when co-precipitation was carried out with the solvent mixture. It was demonstrated that the drug to polymer ratio influenced amorphous content of the SAS co-precipitates. Differential scanning calorimetry thermograms and infrared spectra revealed that there is neither interaction between rifampicin and the polymer nor degradation of rifampicin during co-precipitation. In addition, stability stress tests on SAS co-precipitates were carried out at 75% relative humidity and room temperature in order to evaluate their physical stability. SAS co-precipitates were X-ray amorphous and remained stable after 6months of storage. The SAS co-precipitation process using a mixture of ethyl acetate/dimethyl sulfoxide demonstrates that this strategy can

An Innovative Metric to Evaluate Satellite Precipitation's Spatial Distribution

Science.gov (United States)

Liu, H.; Chu, W.; Gao, X.; Sorooshian, S.

2011-12-01

Thanks to its capability to cover the mountains, where ground measurement instruments cannot reach, satellites provide a good means of estimating precipitation over mountainous regions. In regions with complex terrains, accurate information on high-resolution spatial distribution of precipitation is critical for many important issues, such as flood/landslide warning, reservoir operation, water system planning, etc. Therefore, in order to be useful in many practical applications, satellite precipitation products should possess high quality in characterizing spatial distribution. However, most existing validation metrics, which are based on point/grid comparison using simple statistics, cannot effectively measure satellite's skill of capturing the spatial patterns of precipitation fields. This deficiency results from the fact that point/grid-wised comparison does not take into account of the spatial coherence of precipitation fields. Furth more, another weakness of many metrics is that they can barely provide information on why satellite products perform well or poor. Motivated by our recent findings of the consistent spatial patterns of the precipitation field over the western U.S., we developed a new metric utilizing EOF analysis and Shannon entropy. The metric can be derived through two steps: 1) capture the dominant spatial patterns of precipitation fields from both satellite products and reference data through EOF analysis, and 2) compute the similarities between the corresponding dominant patterns using mutual information measurement defined with Shannon entropy. Instead of individual point/grid, the new metric treat the entire precipitation field simultaneously, naturally taking advantage of spatial dependence. Since the dominant spatial patterns are shaped by physical processes, the new metric can shed light on why satellite product can or cannot capture the spatial patterns. For demonstration, a experiment was carried out to evaluate a satellite

Climatology and Interannual Variability of Quasi-Global Intense Precipitation Using Satellite Observations

Science.gov (United States)

Ricko, Martina; Adler, Robert F.; Huffman, George J.

2016-01-01

Climatology and variations of recent mean and intense precipitation over a near-global (50 deg. S 50 deg. N) domain on a monthly and annual time scale are analyzed. Data used to derive daily precipitation to examine the effects of spatial and temporal coverage of intense precipitation are from the current Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) 3B42 version 7 precipitation product, with high spatial and temporal resolution during 1998 - 2013. Intense precipitation is defined by several different parameters, such as a 95th percentile threshold of daily precipitation, a mean precipitation that exceeds that percentile, or a fixed threshold of daily precipitation value [e.g., 25 and 50 mm day(exp -1)]. All parameters are used to identify the main characteristics of spatial and temporal variation of intense precipitation. High correlations between examined parameters are observed, especially between climatological monthly mean precipitation and intense precipitation, over both tropical land and ocean. Among the various parameters examined, the one best characterizing intense rainfall is a fraction of daily precipitation Great than or equal to 25 mm day(exp. -1), defined as a ratio between the intense precipitation above the used threshold and mean precipitation. Regions that experience an increase in mean precipitation likely experience a similar increase in intense precipitation, especially during the El Nino Southern Oscillation (ENSO) events. Improved knowledge of this intense precipitation regime and its strong connection to mean precipitation given by the fraction parameter can be used for monitoring of intense rainfall and its intensity on a global to regional scale.

Precipitation Intensity Effects on Groundwater Recharge in the Southwestern United States

Directory of Open Access Journals (Sweden)

Brian F. Thomas

2016-03-01

Full Text Available Episodic recharge as a result of infrequent, high intensity precipitation events comprises the bulk of groundwater recharge in arid environments. Climate change and shifts in precipitation intensity will affect groundwater continuity, thus altering groundwater recharge. This study aims to identify changes in the ratio of groundwater recharge and precipitation, the R:P ratio, in the arid southwestern United States to characterize observed changes in groundwater recharge attributed to variations in precipitation intensity. Our precipitation metric, precipitation intensity magnification, was used to investigate the relationship between the R:P ratio and precipitation intensity. Our analysis identified significant changes in the R:P ratio concurrent with decreases in precipitation intensity. The results illustrate the importance of precipitation intensity in relation to groundwater recharge in arid regions and provide further insights for groundwater management in nonrenewable groundwater systems and in a changing climate.

Cesium removal and kinetics equilibrium: Precipitation kinetics

International Nuclear Information System (INIS)

Barnes, M.J.

1999-01-01

This task consisted of both non-radioactive and radioactive (tracer) tests examining the influence of potentially significant variables on cesium tetraphenylborate precipitation kinetics. The work investigated the time required to reach cesium decontamination and the conditions that affect the cesium precipitation kinetics

Investigation of Asphaltene Precipitation at Elevated Temperature

DEFF Research Database (Denmark)

Andersen, Simon Ivar; Lindeloff, Niels; Stenby, Erling Halfdan

1998-01-01

In order to obtain quantitative data on the asphaltene precipitation induced by the addition of n-alkane (heptane) at temperatures above the normal boiling point of the precipitant, a high temperature/high pressure filtration apparatus has been constructed. Oil and alkane are mixed...

Annual Precipitation Fluctuation and Spatial Differentiation Characteristics of the Horqin Region

Directory of Open Access Journals (Sweden)

Liangxu Liu

2017-01-01

Full Text Available Precipitation is the main water source for vegetation survival in arid and semi-arid areas. However, previous studies always focus on the effects of precipitation in different time scales, but ignore the effects of precipitation in different spatial scales. To further study the effects of precipitation fluctuation in different spatial scales, we used the wavelet analysis method to analyze its temporal and spatial change based on data from eighteen meteorological stations during 1961–2015 in Horqin region. Results showed that: (1 from the overall tendency of precipitation changes, the precipitation inter-annual variations in Horqin region had the tendency of gradually decreasing from the southeast (District IV to the northwest; (2 the precipitation anomalies of District I–IV between 1960 and 1980 were small and approximate to the normal value; (3 in the time scale of 23–32 years, the cyclical fluctuations were very significant and the annual precipitation underwent two cyclical fluctuations from a period of low precipitation to a period of high precipitation; and (4 as results of analyzing the spatial wavelet variance of sub-region, the main cycle of precipitation in District I, District II and District III was between 10 and 11 years, while the main cycle of precipitation in District IV was 25 years. The main conclusions include the following. (1 This region tended to be arid, and the precipitation gradually decreased from the southeast (District IV to northwest (District I. (2 The influence of spatial differentiation characteristics on precipitation fluctuation in this region was cyclical fluctuation, which gradually decreased from the southeast to the northwest. The length of the cyclical change period gradually shortened. In the first main cycle, whose annual precipitation changes were most significant, the changing characteristic was District IV and District I decreased from 25 years to 10 years. (3 Predicated from the cyclical

Occurrence of refeeding syndrome in adults started on artificial nutrition support: prospective cohort study.

Science.gov (United States)

Rio, Alan; Whelan, Kevin; Goff, Louise; Reidlinger, Dianne Patricia; Smeeton, Nigel

2013-01-11

, acute circulatory fluid overload and disturbance to organ function following artificial nutrition support and were diagnosed with refeeding syndrome. There were no deaths attributable to the refeeding syndrome, but (5.3% 13/243) participants died during the feeding period and (28% 68/243) died during hospital admission. Death of these participants was due to cerebrovascular accident, traumatic injury, respiratory failure, organ failure or end-of-life causes. Refeeding syndrome was a rare, survivable phenomenon that occurred during hypocaloric nutrition support in participants identified at risk. Independent predictors for refeeding syndrome were starvation and baseline low-serum magnesium concentration. Intravenous carbohydrate infusion prior to artificial nutrition support may have precipitated the onset of the syndrome.

Precipitated iron. A limit on gettering efficacy in multicrystalline silicon

Energy Technology Data Exchange (ETDEWEB)

Fenning, D.P.; Hofstetter, J.; Bertoni, M.I.; Buonassisi, T. [Massachusetts Institute of Technology MIT, Cambridge, Massachusetts 02139 (United States); Coletti, G. [ECN Solar Energy, Westerduinweg 3, NL-1755 LE Petten (Netherlands); Lai, B. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Del Canizo, C. [Instituto de Energia Solar, Universidad Politecnica de Madrid, 28040 Madrid (Spain)

2013-01-31

A phosphorus diffusion gettering model is used to examine the efficacy of a standard gettering process on interstitial and precipitated iron in multicrystalline silicon. The model predicts a large concentration of precipitated iron remaining after standard gettering for most as-grown iron distributions. Although changes in the precipitated iron distribution are predicted to be small, the simulated post-processing interstitial iron concentration is predicted to depend strongly on the as-grown distribution of precipitates, indicating that precipitates must be considered as internal sources of contamination during processing. To inform and validate the model, the iron distributions before and after a standard phosphorus diffusion step are studied in samples from the bottom, middle, and top of an intentionally Fe-contaminated laboratory ingot. A census of iron-silicide precipitates taken by synchrotron-based X-ray fluorescence microscopy confirms the presence of a high density of iron-silicide precipitates both before and after phosphorus diffusion. A comparable precipitated iron distribution was measured in a sister wafer after hydrogenation during a firing step. The similar distributions of precipitated iron seen after each step in the solar cell process confirm that the effect of standard gettering on precipitated iron is strongly limited as predicted by simulation. Good agreement between the experimental and simulated data supports the hypothesis that gettering kinetics is governed by not only the total iron concentration but also by the distribution of precipitated iron. Finally, future directions based on the modeling are suggested for the improvement of effective minority carrier lifetime in multicrystalline silicon solar cells.

Scavenging of radon daughters by precipitation from the atmosphere

Energy Technology Data Exchange (ETDEWEB)

Fujinami, Naoto [Kyoto Prefectural Inst. of Hygienic and Environmental Sciences (Japan)

1997-02-01

By the continuous measurement of the radon daughters concentration in the rain and snow water and atmosphere and the data analysis, the following results were obtained. The radon daughters concentration was almost constant in the rain and snow water in spite of the length during weather without precipitation. It has not tendency to show the high concentration of radon daughters in precipitation and snow during beginning of them. When the precipitation intensity is constant, it`s concentration does not change during precipitation and snowfall. The concentration does not depend on the amount of precipitation, but on the precipitation intensity. We did not observe a correlation between the radon daughters concentration in the rain and snow water and that in the surface air. The atmospheric concentration was decreased by precipitation and snowfall, but that of rain and snow water did not decrease. The above results seems to show that the contribution of washout under the cloud to radon daughters in rain and snow water is small and that of rainout in the cloud is large. This result is agreement with the Jacob`s experimental results. (S.Y.)

Arsenic removal from acidic solutions with biogenic ferric precipitates.

Science.gov (United States)

Ahoranta, Sarita H; Kokko, Marika E; Papirio, Stefano; Özkaya, Bestamin; Puhakka, Jaakko A

2016-04-05

Treatment of acidic solution containing 5g/L of Fe(II) and 10mg/L of As(III) was studied in a system consisting of a biological fluidized-bed reactor (FBR) for iron oxidation, and a gravity settler for iron precipitation and separation of the ferric precipitates. At pH 3.0 and FBR retention time of 5.7h, 96-98% of the added Fe(II) precipitated (99.1% of which was jarosite). The highest iron oxidation and precipitation rates were 1070 and 28mg/L/h, respectively, and were achieved at pH 3.0. Subsequently, the effect of pH on arsenic removal through sorption and/or co-precipitation was examined by gradually decreasing solution pH from 3.0 to 1.6 (feed pH). At pH 3.0, 2.4 and 1.6, the highest arsenic removal efficiencies obtained were 99.5%, 80.1% and 7.1%, respectively. As the system had ferric precipitates in excess, decreased arsenic removal was likely due to reduced co-precipitation at pHremoves iron and arsenic from acidic solutions, indicating potential for mining wastewater treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Seckel syndrome: an overdiagnosed syndrome.

OpenAIRE

Thompson, E; Pembrey, M

1985-01-01

Five children in whom a diagnosis of Seckel syndrome had previously been made were re-examined in the genetic unit. One child had classical Seckel syndrome, a sib pair had the features of the syndrome with less severe short stature, and in two children the diagnosis was not confirmed. Seckel syndrome is only one of a group of low birth weight microcephalic dwarfism and careful attention should be paid to fulfillment of the major criteria defined by Seckel before the diagnosis is made. There r...

Heterogeneous precipitation of niobium carbide in the ferrite by Monte Carlo simulations; Cinetique de precipitation heterogene du carbure de niobium dans la ferrite

Energy Technology Data Exchange (ETDEWEB)

Hin, C

2005-12-15

The precipitation of niobium carbides in industrial steels is commonly used to control the recrystallization process or the amount of interstitial atoms in solid solution. It is then important to understand the precipitation kinetics and especially the competition between homogeneous and heterogeneous precipitation, since both of them have been observed experimentally, depending on they alloy composition, microstructure and thermal treatments. We propose Monte Carlo simulations of NbC precipitation in {open_square}-iron, based on a simple atomic description of the main parameters which control the kinetic pathway: - Realistic diffusion properties, with a rapid diffusion of C atoms by interstitial jumps and a slower diffusion of Fe and Nb atoms by vacancy jumps; - A model of grain boundaries which reproduces the segregation properties of Nb and C; - A model of dislocation which interacts with solute atoms through local segregation energies and long range elastic field; - A point defect source which drives the vacancy concentration towards its equilibrium value. Depending on the precipitation conditions, Monte Carlo simulations predict different kinetic behaviors, including a transient precipitation of metastable carbides, an early segregation stage of C, wetting phenomena at grain boundaries and on dislocations and a competition between homogeneous and heterogeneous NbC precipitation. Concerning the last point, we highlight that long range elastic field due to dislocation favors clearly the heterogeneous precipitation on dislocations. To understand this effect, we have developed a heterogeneous nucleation model including the calculation of the local concentration of solute atoms around the dislocation, the change of the solubility limit relative to the solubility limit in bulk and the energy of precipitates in an elastic field. We have concluded that elastic field favors the heterogeneous precipitation through the fall in nucleation barrier. (author)

Global Precipitation Responses to Land Hydrological Processes

Science.gov (United States)

Lo, M.; Famiglietti, J. S.

2012-12-01

Several studies have established that soil moisture increases after adding a groundwater component in land surface models due to the additional supply of subsurface water. However, impacts of groundwater on the spatial-temporal variability of precipitation have received little attention. Through the coupled groundwater-land-atmosphere model (NCAR Community Atmosphere Model + Community Land Model) simulations, this study explores how groundwater representation in the model alters the precipitation spatiotemporal distributions. Results indicate that the effect of groundwater on the amount of precipitation is not globally homogeneous. Lower tropospheric water vapor increases due to the presence of groundwater in the model. The increased water vapor destabilizes the atmosphere and enhances the vertical upward velocity and precipitation in tropical convective regions. Precipitation, therefore, is inhibited in the descending branch of convection. As a result, an asymmetric dipole is produced over tropical land regions along the equator during the summer. This is analogous to the "rich-get-richer" mechanism proposed by previous studies. Moreover, groundwater also increased short-term (seasonal) and long-term (interannual) memory of precipitation for some regions with suitable groundwater table depth and found to be a function of water table depth. Based on the spatial distributions of the one-month-lag autocorrelation coefficients as well as Hurst coefficients, air-land interaction can occur from short (several months) to long (several years) time scales. This study indicates the importance of land hydrological processes in the climate system and the necessity of including the subsurface processes in the global climate models.

Conditions for precipitation of copper phases in DWPF waste glass

International Nuclear Information System (INIS)

Schumacher, R.F.; Ramsey, W.G.

1993-01-01

The Defense Waste Processing Facility (DWPF) precipitate hydrolysis process requires the use of copper formate catalyst. The expected absorbed radiation doses to the precipitate require levels of copper formate that increase the potential for the precipitation of metallic copper in the DWPF Melter. The conditions required to avoid the precipitation of copper are described

40 CFR 434.63 - Effluent limitations for precipitation events.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Effluent limitations for precipitation... SOURCE PERFORMANCE STANDARDS Miscellaneous Provisions § 434.63 Effluent limitations for precipitation... discharge or increase in the volume of a discharge caused by precipitation within any 24 hour period less...

Dissolving of Nb and Ti carbonitride precipitates in microalloyed steels

Institute of Scientific and Technical Information of China (English)

Wenjin Nie; Shanwu Yang; Shaoqiang Yuan; Xinlai He

2003-01-01

The dissolving behaviour of Nb and Ti carbonitride precipitates in microalloyed steels during isothermal holding at 1300℃ was investigated by Transmission electron microscopy (TEM) and energy dispersion x-ray spectrum (EDX). It was found that all precipitates in Nb-Ti microalloyed steel are (Nb, Ti)(C,N). With holding time increasing, the atomic ratio of Nb/Ti in precipitates decrease gradually. These precipitates still existe even after holding for 48 h at 1300℃ while Nb(C,N) precipitates dissolve away in Nb microalloyed steel only after 4 h at the same temperature. These results show that formation and thermostability of precipitates are considerably influenced by interaction between Nb and Ti.

Using GRACE to constrain precipitation amount over cold mountainous basins

Science.gov (United States)

Behrangi, Ali; Gardner, Alex S.; Reager, John T.; Fisher, Joshua B.

2017-01-01

Despite the importance for hydrology and climate-change studies, current quantitative knowledge on the amount and distribution of precipitation in mountainous and high-elevation regions is limited due to instrumental and retrieval shortcomings. Here by focusing on two large endorheic basins in High Mountain Asia, we show that satellite gravimetry (Gravity Recovery and Climate Experiment (GRACE)) can be used to provide an independent estimate of monthly accumulated precipitation using mass balance equation. Results showed that the GRACE-based precipitation estimate has the highest agreement with most of the commonly used precipitation products in summer, but it deviates from them in cold months, when the other products are expected to have larger errors. It was found that most of the products capture about or less than 50% of the total precipitation estimated using GRACE in winter. Overall, Global Precipitation Climatology Project (GPCP) showed better agreement with GRACE estimate than other products. Yet on average GRACE showed 30% more annual precipitation than GPCP in the study basins. In basins of appropriate size with an absence of dense ground measurements, as is a typical case in cold mountainous regions, we find GRACE can be a viable alternative to constrain monthly and seasonal precipitation estimates from other remotely sensed precipitation products that show large bias.

Probability Distribution and Projected Trends of Daily Precipitation in China

Institute of Scientific and Technical Information of China (English)

CAO; Li-Ge; ZHONG; Jun; SU; Bu-Da; ZHAI; Jian-Qing; Macro; GEMMER

2013-01-01

Based on observed daily precipitation data of 540 stations and 3,839 gridded data from the high-resolution regional climate model COSMO-Climate Limited-area Modeling(CCLM)for 1961–2000,the simulation ability of CCLM on daily precipitation in China is examined,and the variation of daily precipitation distribution pattern is revealed.By applying the probability distribution and extreme value theory to the projected daily precipitation(2011–2050)under SRES A1B scenario with CCLM,trends of daily precipitation series and daily precipitation extremes are analyzed.Results show that except for the western Qinghai-Tibetan Plateau and South China,distribution patterns of the kurtosis and skewness calculated from the simulated and observed series are consistent with each other;their spatial correlation coefcients are above 0.75.The CCLM can well capture the distribution characteristics of daily precipitation over China.It is projected that in some parts of the Jianghuai region,central-eastern Northeast China and Inner Mongolia,the kurtosis and skewness will increase significantly,and precipitation extremes will increase during 2011–2050.The projected increase of maximum daily rainfall and longest non-precipitation period during flood season in the aforementioned regions,also show increasing trends of droughts and floods in the next 40 years.

Application of physical scaling towards downscaling climate model precipitation data

Science.gov (United States)

Gaur, Abhishek; Simonovic, Slobodan P.

2018-04-01

Physical scaling (SP) method downscales climate model data to local or regional scales taking into consideration physical characteristics of the area under analysis. In this study, multiple SP method based models are tested for their effectiveness towards downscaling North American regional reanalysis (NARR) daily precipitation data. Model performance is compared with two state-of-the-art downscaling methods: statistical downscaling model (SDSM) and generalized linear modeling (GLM). The downscaled precipitation is evaluated with reference to recorded precipitation at 57 gauging stations located within the study region. The spatial and temporal robustness of the downscaling methods is evaluated using seven precipitation based indices. Results indicate that SP method-based models perform best in downscaling precipitation followed by GLM, followed by the SDSM model. Best performing models are thereafter used to downscale future precipitations made by three global circulation models (GCMs) following two emission scenarios: representative concentration pathway (RCP) 2.6 and RCP 8.5 over the twenty-first century. The downscaled future precipitation projections indicate an increase in mean and maximum precipitation intensity as well as a decrease in the total number of dry days. Further an increase in the frequency of short (1-day), moderately long (2-4 day), and long (more than 5-day) precipitation events is projected.

Study of aluminum nitride precipitation in Fe- 3%Si steel

Directory of Open Access Journals (Sweden)

F.L. Alcântara

2013-01-01

Full Text Available For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese sulphides and aluminium nitride delay normal grain growth during primary recrystallization, causing preferential growth of grains with Goss orientation during secondary recrystallization. The sulphides precipitate during the hot rolling process. The aluminium nitride particles are formed during hot rolling and the hot band annealing process. In this work AlN precipitation during hot deformation of a high permeability grain oriented 3%Si steel is examined. In the study, transfer bar samples were submitted to controlled heating, compression and cooling treatments in order to simulate a reversible hot rolling finishing. The samples were analyzed using the transmission electron microscope (TEM in order to identify the precipitates and characterize size distribution. Precipitate extraction by dissolution method and analyses by inductively coupled plasma optical emission spectrometry (ICP-OES were used to quantify the precipitation. The results allowed to describe the precipitation kinetics by a precipitation-time-temperature (PTT diagram for AlN formation during hot rolling.