O LIVRO DE ESCUTAS DE SALVATORE SCIARRINO
Directory of Open Access Journals (Sweden)
André Ribeiro
2014-12-01
Full Text Available Trata-se de uma leitura crítica do livro “Figure della musica da Beethoven a oggi” do compositor Salvatore Sciarrino. Especificamente, trata-se de apresentar a escuta musical, segundo as ideias do compositor, como um campo orgânico de interação, inventividade e coexistência de modos de escuta encarnados num naturalismo musical diretamente relacionado às estruturas perceptivas da música. Usamos como referências nesta leitura analítica os próprios textos e ideias do autor, difundidas por meio de entrevistas disponibilizadas na web.
Book review, Sanità animale, Salvatore Montinaro
Directory of Open Access Journals (Sweden)
Manuel Graziani
2013-03-01
Full Text Available Un manuale strutturato per fornire un quadro d'insieme della materia e chiarire il metodo logico con il quale trovare i riferimenti scientifici e normativi necessari per affrontare il lavoro di tutti i giorni: così viene presentato Sanità animale, un volume che rispetto ai pochi testi analoghi sul mercato, si distingue per l'utilizzo parco di stralci normativi, comunque sistematicamente citati, in modo da renderne agevole la consultazione. L'attenzione maggiore è spostata verso l'analisi scientifica e normativa delle problematiche affrontate, delle peculiarità delle singole malattie e dei principi d'intervento sul campo. Il medico veterinario Salvatore Montinaro, forte dell'esperienza maturata in diverse amministrazioni (Regione, ASL, IZS riesce nell'intento di descrivere in maniera semplice, ma completa e dettagliata, il funzionamento della sanità animale e della lotta alle malattie diffusive animali. Come esplicita nell'introduzione del capitolo Norme Veterinarie e SSN: "Non si cercherà in questa sede di ripercorrere la storia della veterinaria pubblica, dal codice di Hammurabi in poi: ci si limiterà piuttosto a uno sguardo retrospettivo nella storia recente, finalizzato a identificare in modo sistematico, partendo dal generale per arrivare al particolare, i principali punti di riferimento che caratterizzano il quadro normativo della sanità pubblica veterinaria". Anche per questo il manuale è indirizzato soprattutto a coloro che già lavorano, o che intendono lavorare, nei servizi veterinari di sanità animale delle Aziende Sanitarie Locali, ponendosi come un testo "professionale" e un sussidio tecnico da avere a portata di mano. Salvatore Montinaro, classe 1967, svolge la sua attività professionale come dirigente del servizio veterinario di sanità animale della ASL di Nuoro, inoltre, fa parte del gruppo di esperti comunitari del TAIEX ed è consulente tecnico della FAO.
Inhomogeneous generalization of some Bianchi models
Carmeli, M.; Charach, Ch.
1980-02-01
Vacuum Bianchi models which can be transformed to the Einstein-Rosen metric are considered. The models are used in order to construct new inhomogeneous universes, which are generalizations of Bianchi cosmologies of types III, V and VIh. Recent generalizations of these Bianchi models, considered by Wainwright et al., are also discussed.
Diagramas de Bianchi para Susy
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Sara Cruz y Cruz
2006-01-01
Full Text Available Se revisa el origen de los solitones como soluciones de la ecuación de Korteweg-de Vries y su presencia en la formulación supersimétrica de la Mecánica Cuántica. Se introducen los diagramas de Bianchi como una herramienta simbólica para construir socios supersimétricos de un Hamiltoniano dado.
Brane and Nonisotropic Bianchi Cosmology
Naboulsi, R
2003-01-01
In this letter, we use Einstein field equations in the presence of gravitino cosmological density derived in a previous paper [1] to study a spatially honogenous, nonisotropic cosmological model, in particular the Bianchi IV model. We find a axisymmetric Universe, free of singularity in the past, asymptotically flat as time grows, and admit the presence of gravitino mass as missing energy and positive cosmological constant as Lambda > 3m^2.
Bianchi type I string cosmologies
Indian Academy of Sciences (India)
D N Pant; Sanjay Oli
2003-03-01
By making use of Letelier’s form of energy–momentum tensor for a cloud of stringdust we present some classes of solutions of general relativistic ﬁeld equations which describe cosmological string-dust models in Bianchi type I space-time. Some of the classes of models obey Takabayashi’s equation of state whereas a class of models exhibits inﬂation in the initial stage. Two of the classes presented here have Kasner’s space-time as past asymptote.
In ricordo di Vittorio Bianchi
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Maurizio Cutolo
2011-09-01
Full Text Available Vittorio Bianchi fu Ernesto e fu Mary Sbertoli naque a Cogoleto (Genova il 17 febbraio 1919. Laureato in Medicina e Chirurgia presso l’Università di Genova nel 1943 con lode fu Allievo interno della Clinica Medica di Genova negli anni 1942 e 1943, Assistente Volontario alla Clinica Medica di Perugia, quindi della Clinica Medica di Genova negli anni seguenti dove fu nominato Assistente di ruolo per concorso nel 1950. Successivamente Assistente di ruolo alla Patologia Medica diretta dal prof. Aminta Fieschi nel periodo 1954- 1969....
Higher-dimensional Bianchi type-VIh cosmologies
Lorenz-Petzold, D.
1985-09-01
The higher-dimensional perfect fluid equations of a generalization of the (1 + 3)-dimensional Bianchi type-VIh space-time are discussed. Bianchi type-V and Bianchi type-III space-times are also included as special cases. It is shown that the Chodos-Detweiler (1980) mechanism of cosmological dimensional-reduction is possible in these cases.
Bianchi class A models in Sàez-Ballester's theory
Socorro, J.; Espinoza-García, Abraham
2012-08-01
We apply the Sàez-Ballester (SB) theory to Bianchi class A models, with a barotropic perfect fluid in a stiff matter epoch. We obtain exact classical solutions à la Hamilton for Bianchi type I, II and VIh=-1 models. We also find exact quantum solutions to all Bianchi Class A models employing a particular ansatz for the wave function of the universe.
Quantum Supersymmetric Bianchi IX Cosmology
Damour, Thibault
2014-01-01
We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing to one timelike dimension the action of D=4 simple supergravity for a Bianchi IX cosmological model. After imposition of the diffeomorphism constraints, the wave function of the Universe becomes a spinor of Spin(8,4) depending on the three squashing parameters, which satisfies Dirac, and Klein-Gordon-like, wave equations describing the propagation of a quantum spinning particle reflecting off spin-dependent potential walls. The algebra of the susy constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the maximally compact sub-algebra of the rank-3 hyperbolic Kac-Moody algebra AE3. The (quartic-in-fermions) squared-mass term entering the Klein-Gordon-like equation has several remarkable properties: 1)it commutes with all the other (Kac-Moody-related) building blocks of the Hamiltonian; 2)it is a quad...
Bianchi I meets the Hubble diagram
Schucker, Thomas; Valent, Galliano
2014-01-01
We improve existing fits of the Bianchi I metric to the Hubble diagram of supernovae and find an intriguing yet non-significant signal for anisotropy that should be verified or falsified in the near future by the Large Synoptic Survey Telescope. Since the literature contains two different formulas for the apparent luminosity as a function of time of flight in Bianchi I metrics, we present an independent derivation confirming the result by Saunders (1969). The present fit differs from earlier ones by Koivisto & Mota and by Campanelli et al. in that we use Saunders' formula, a larger sample of supernovae, Union 2 and JLA, and we use the general Bianchi I metric with three distinct eigenvalues.
Quantum Einstein-Dirac Bianchi Universes
Damour, Thibault
2011-01-01
We study the mini--superspace quantization of spatially homogeneous (Bianchi) cosmological universes sourced by a Dirac spinor field. The quantization of the homogeneous spinor leads to a finite-dimensional fermionic Hilbert space and thereby to a multi-component Wheeler-DeWitt equation whose main features are: (i) the presence of spin-dependent Morse-type potentials, and (ii) the appearance of a q-number squared-mass term, which is of order ${\\cal O}(\\hbar^2)$, and which is affected by ordering ambiguities. We give the exact quantum solution of the Bianchi type-II system (which contains both scattering states and bound states), and discuss the main qualitative features of the quantum dynamics of the (classically chaotic) Bianchi type-IX system. We compare the exact quantum dynamics of fermionic cosmological billiards to previous works that described the spinor field as being either classical or Grassmann-valued.
Wave Equations in Bianchi Space-Times
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S. Jamal
2012-01-01
Full Text Available We investigate the wave equation in Bianchi type III space-time. We construct a Lagrangian of the model, calculate and classify the Noether symmetry generators, and construct corresponding conserved forms. A reduction of the underlying equations is performed to obtain invariant solutions.
Gauged supergravities from Bianchi's group manifolds
Bergshoeff, E; Gran, U; Linares, R; Nielsen, M; Ortin, T; Roest, D
2004-01-01
We construct maximal D = 8 gauged supergravities by the reduction of D = I I supergravity over three-dimensional group manifolds. Such manifolds are classified into two classes, A and B, and eleven types. This Bianchi classification carries over to the gauged supergravities. The class A theories hav
Quantum supersymmetric Bianchi IX cosmology
Damour, Thibault; Spindel, Philippe
2014-11-01
We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing (to one timelike dimension) the action of D =4 simple supergravity for a S U (2 ) -homogeneous (Bianchi IX) cosmological model. The quantization of the homogeneous gravitino field leads to a 64-dimensional fermionic Hilbert space. After imposition of the diffeomorphism constraints, the wave function of the Universe becomes a 64-component spinor of spin(8,4) depending on the three squashing parameters, which satisfies Dirac-like, and Klein-Gordon-like, wave equations describing the propagation of a "quantum spinning particle" reflecting off spin-dependent potential walls. The algebra of the supersymmetry constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the (infinite-dimensional) maximally compact subalgebra of the rank-3 hyperbolic Kac-Moody algebra A E3 . The (quartic-in-fermions) squared-mass term μ^ 2 entering the Klein-Gordon-like equation has several remarkable properties: (i) it commutes with all the other (Kac-Moody-related) building blocks of the Hamiltonian; (ii) it is a quadratic function of the fermion number NF; and (iii) it is negative in most of the Hilbert space. The latter property leads to a possible quantum avoidance of the singularity ("cosmological bounce"), and suggests imposing the boundary condition that the wave function of the Universe vanish when the volume of space tends to zero (a type of boundary condition which looks like a final-state condition when considering the big crunch inside a black hole). The space of solutions is a mixture of "discrete-spectrum states" (parametrized by a few constant parameters, and known in explicit form) and of continuous-spectrum states (parametrized by arbitrary functions entering some initial-value problem). The predominantly negative values of the squared-mass term lead to a "bottle
Singularity-free Bianchi spaces with nonlinear electrodynamics
García-Salcedo, R; Garcia-Salcedo, Ricardo; Breton, Nora
2004-01-01
In this paper we present the analysis to determine the existence of singularities in spatially homogeneous anisotropic universes filled with nonlinear electromagnetic radiation. These spaces are conformal to Bianchi spaces admitting a three parameter group of motions G$_3$. We study analytical extensions as well as geodesic completeness. It is shown that with nonlinear electromagnetic field some of the Bianchi spaces are geodesically complete, like G$_3$II and G$_3$VIII; however Bianchi G$_3$IX presents the phenomenon of geodesics that are imprisoned. In contrast, diagonal Bianchi spaces like G$_3$I, G$_3$III and Kantowski-Sachs have a finite time existence ending in a scalar polynomial curvature singularity.
Stability of Bianchi attractors in Gauged Supergravity
Inbasekar, Karthik
2013-01-01
In this paper, we analyse the stability of extremal black brane horizons with homogeneous symmetry in the spatial directions in five dimensional gauged supergravity, under the fluctuations of the scalar fields about their attractor values. We examine the scalar fluctuation equations at the linearised level and demand that the fluctuations vanish as one approaches the horizon. Imposing certain restrictions on the Killing vectors used for gauging we find that the necessary conditions for stability are satisfied only by a subclass of the Bianchi metrics whose symmetry group factorises into a two dimensional Lifshitz symmetry and any homogeneous symmetry group given by the Bianchi classification. We apply these results to a simple example of a gauged supergravity model with one vector multiplet to find the stable attractors.
Compact invariant sets of the Bianchi VIII and Bianchi IX Hamiltonian systems
Energy Technology Data Exchange (ETDEWEB)
Starkov, Konstantin E., E-mail: konst@citedi.mx [CITEDI-IPN, Av. del Parque 1310, Mesa de Otay, Tijuana, BC (Mexico)
2011-08-22
In this Letter we prove that all compact invariant sets of the Bianchi VIII Hamiltonian system are contained in the set described by several simple linear equalities and inequalities. Moreover, we describe invariant domains in which the phase flow of this system has no recurrence property and show that there are no periodic orbits and neither homoclinic, nor heteroclinic orbits contained in the zero level set of its Hamiltonian. Similar results are obtained for the Bianchi IX Hamiltonian system. -- Highlights: → Zero level set of Hamiltonian of Bianchi VIII/IX systems contains no periodic orbits. → Similar conditions for homoclinic/heteroclinic orbits are given. → General nonexistence conditions of compact invariant sets are got.
Inhomogeneous generalizations of Bianchi type VIh models with perfect fluid
Roy, S. R.; Prasad, A.
1991-07-01
Inhomogeneous universes admitting an Abelian G2 of isometry and filled with perfect fluid have been derived. These contain as special cases exact homogeneous universes of Bianchi type VIh. Many of these universes asymptotically tend to homogeneous Bianchi VIh universes. The models have been discussed for their physical and kinematical behaviors.
“Nell’occhio che riscopre la luce”: tempo, Storia e memoria nella poesia di Salvatore Quasimodo
Directory of Open Access Journals (Sweden)
Alessandro Martini
2015-06-01
Full Text Available La riflessione sul rapporto dell’uomo con il tempo e con la storia percorre senza soluzione di continuità l’opera poetica di Salvatore Quasimodo. Spesso a disagio in una dimensione temporale fissa e definita, schiacciato tra dolore dell’esilio, insensatezza della guerra e crisi del dopoguerra, il poeta interroga gli evi passati e le ere future in cerca di un’armonia che appare il più delle volte sfuggente.
“Nell’occhio che riscopre la luce”: tempo, Storia e memoria nella poesia di Salvatore Quasimodo
Directory of Open Access Journals (Sweden)
Alessandro Martini
2015-06-01
Full Text Available La riflessione sul rapporto dell’uomo con il tempo e con la storia percorre senza soluzione di continuità l’opera poetica di Salvatore Quasimodo. Spesso a disagio in una dimensione temporale fissa e definita, schiacciato tra dolore dell’esilio, insensatezza della guerra e crisi del dopoguerra, il poeta interroga gli evi passati e le ere future in cerca di un’armonia che appare il più delle volte sfuggente.
Strictly isospectral Bianchi type II cosmological models
Rosu, H C; Obregón, O
1996-01-01
We show that, in the Q=0 factor ordering, the Wheeler-DeWitt equation for the Bianchi type ll model with the Ansatz \\rm \\Psi=A\\, e^{\\pm \\Phi(q^{\\mu})}, due to its one-dimensional character, may be approached by the strictly isospectral Darboux-Witten technique in standard supersymmetric quantum mechanics. One-parameter families of cosmological potentials and normalizable `wavefunctions of the universe' are exhibited. The isospectral method can be used to introduce normalizable wavefunctions in quantum cosmology.
Bianchi IX Cosmologies and the Golden Ratio
Bryant, M S
2016-01-01
Solutions to the Einstein equations for Bianchi IX cosmologies are examined through the use of Ellis MacCallum Wainwright (expansion-normalized) variables. Using an iterative map derived from the Einstein equations one can construct an infinite number of periodic solutions. The simplest periodic solutions consist of 3-cycles. It is shown that for 3-cycles the time series of the logarithms of the expansion-normalized spatial curvature components vs normalized time (which is runs backwards towards the initial singularity), generates a set of self-similar golden rectangles. In addition the golden ratio appears in other aspects of the same time series representation.
Bianchi I solutions of effective quadratic gravity
Müller, Daniel
2012-01-01
It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "flat" model $E^3$ for this effective gravity are given. It must be emphasized that although numeric, these solutions are exact in the sense that they depend only on the precision of the machine. The solutions are identified asymptotically in a certain sense. It is found solutions which asymptote de Sitter space, Minkowski space and a singularity. This work is a generalization for non diagonal spatial metrics of a previous result obtained by one of us and a collaborator for Bianchi $I$ spaces.
Bianchi-I cosmology from causal thermodynamics
Bittencourt, Eduardo; Klippert, Renato
2016-01-01
We investigate diagonal Bianchi-I spacetimes in the presence of viscous fluids by using the shear and the anisotropic pressure components as the basic variables, where the viscosity is driven by the (second-order) causal thermodynamics. A few exact solutions are presented, among which we mention the anisotropic versions of de Sitter/anti-de Sitter geometries as well as an asymptotically isotropic spacetime presenting an effective constant cosmic acceleration without any cosmological constant. The qualitative analysis of the solutions for barotropic fluids with linear equations of state suggests that the behaviour is quite general.
Scalar-Tensor Bianchi VI Models
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J. A. Belinchón
2013-01-01
Full Text Available We study how may vary the gravitational and the cosmological “constants,” ( and in several scalar-tensor theories with Bianchi III, , and symmetries. By working under the hypothesis of self-similarity we find exact solutions for two different theoretical models, which are the Jordan-Brans-Dicke (JBD with and the usual JBD model with potential (that mimics the behaviour of . We compare both theoretical models, and some physical and geometrical properties of the solutions are also discussed putting special emphasis on the study of the isotropization of the solutions.
Loop quantum cosmology of Bianchi IX: effective dynamics
Corichi, Alejandro; Montoya, Edison
2017-03-01
We study solutions to the effective equations for the Bianchi IX class of spacetimes within loop quantum cosmology (LQC). We consider Bianchi IX models whose matter content is a massless scalar field, by numerically solving the loop quantum cosmology effective equations, with and without inverse triad corrections. The solutions are classified using certain geometrically motivated classical observables. We show that both effective theories—with lapse N = V and N = 1—resolve the big bang singularity and reproduce the classical dynamics far from the bounce. Moreover, due to the positive spatial curvature, there is an infinite number of bounces and recollapses. We study the limit of large field momentum and show that both effective theories reproduce the same dynamics, thus recovering general relativity. We implement a procedure to identify amongst the Bianchi IX solutions, those that behave like k = 0,1 FLRW as well as Bianchi I, II, and VII0 models. The effective solutions exhibit Bianchi I phases with Bianchi II transitions and also Bianchi VII0 phases, which had not been studied before. We comment on the possible implications of these results for a quantum modification to the classical BKL behaviour.
Loop quantum cosmology of Bianchi IX: Effective dynamics
Corichi, Alejandro
2015-01-01
We study numerically the solutions to the effective equations of Bianchi IX spacetimes within Loop Quantum Cosmology. We consider Bianchi IX models with and without inverse triad corrections whose matter content is a scalar field without mass. The solutions are classified using the classical observables. We show that both effective theories --with lapse N=V and N=1-- solve the big bang singularity and reproduce the classical dynamics far from the bounce. Moreover, due to the spatial compactness, there is an infinity number of bounces and recollapses. We study the limit of large volume and show that both effective theories reproduce the same dynamics, thus recovering general relativity. We implement a procedure to identify amongst the Bianchi IX solutions, those that behave like k=0,1 FLRW as well as Bianchi I, II, and VII_0 models. The effective solutions exhibit Bianchi I phases with Bianchi II transitions and also Bianchi VII_0 phases, which had not been studied before, at the quantum nor effective level. W...
Bianchi-IX string cosmological model in Lyra geometry
Indian Academy of Sciences (India)
F Rahaman; S Chakraborty; N Begum; M Hossain; M Kalam
2003-06-01
A class of cosmological solutions of massive strings for the Bianchi-IX space-time are obtained within the framework of Lyra geometry. Various physical and kinematical properties of the models are discussed.
Tryon's conjecture and Energy and momentum of Bianchi Type Universes
Mishra, Prajyot Kumar; Pattanayak, Pradosh Ranjan; Tripathy, Sunil Kumar
2016-01-01
The energy and momentum of the Bianchi type $III$ universes are obtained using different prescriptions for the energy-momentum complexes in the framework of General Relativity. The energy and momentum of the Bianchi $III$ universe is found to be zero for the M\\o{}ller prescription. For all other prescriptions the energy and momentum vanish when the metric parameter $h$ vanishes. In an earlier work, Tripathy et al. \\cite{SKT15} have obtained the energy and momentum of Bianchi $VI_h$ metric and found that the energy of the Universe vanish only for $h=-1$. This result raised a question: why this specific choice?. We explored the Tryon's conjecture that 'the Universe must have a zero net value for all conserved quantities' to get some ideas on the specific values of this parameter for Bianchi type Universes.
Loop quantum cosmology of Bianchi type IX models
Wilson-Ewing, Edward
2010-01-01
The loop quantum cosmology "improved dynamics" of the Bianchi type IX model are studied. The action of the Hamiltonian constraint operator is obtained via techniques developed for the Bianchi type I and type II models, no new input is required. It is shown that the big bang and big crunch singularities are resolved by quantum gravity effects. We also present the effective equations which provide modifications to the classical equations of motion due to quantum geometry effects.
Loop quantum cosmology of Bianchi type IX models
Wilson-Ewing, Edward
2010-08-01
The loop quantum cosmology “improved dynamics” of the Bianchi type IX model are studied. The action of the Hamiltonian constraint operator is obtained via techniques developed for the Bianchi type I and type II models, no new input is required. It is shown that the big bang and big crunch singularities are resolved by quantum gravity effects. We also present effective equations which provide quantum geometry corrections to the classical equations of motion.
Bianchi Class B Spacetimes with Electromagnetic Fields
Yamamoto, Kei
2011-01-01
We carry out a thorough analysis on a class of cosmological spacetimes which admit three space-like Killing vectors of Bianchi class B and contain electromagnetic fields. Using dynamical system analysis, we show that a family of vacuum plane-wave solutions of the Einstein-Maxwell equations is the stable attractor for expanding universes. Phase dynamics are investigated in detail for particular symmetric models. We integrate the system exactly for some special cases to confirm the qualitative features. Some of the obtained solutions have not been presented previously to the best of our knowledge. Finally, based on those solutions, we discuss the relation between those homogeneous models and perturbations of open FLRW universes. We argue that the vacuum plane-wave modes correspond to a certain long-wavelength limit of electromagnetic perturbations.
Anisotropy and inflation in Bianchi I braneworlds
Energy Technology Data Exchange (ETDEWEB)
Aguirregabiria, Juan M [Fisika Teorikoa eta Zientziaren Historia Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, 644 Posta Kutxatila, 48080 Bilbao (Spain); Chimento, Luis P [Departamento de FIsica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); Lazkoz, Ruth [Fisika Teorikoa eta Zientziaren Historia Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea, 644 Posta Kutxatila, 48080 Bilbao (Spain)
2004-02-21
After a more general assumption on the influence of the bulk on the brane, we extend some conclusions by Maartens et al (2001 Phys. Rev. D 63 063509) and Santos et al (2001 Phys. Rev. D 64 063506) on the asymptotic behaviour of Bianchi I braneworlds. As a consequence of the nonlocal anisotropic stresses induced by the bulk, in most of our models, the brane does not isotropize and the nonlocal energy does not vanish in the limit in which the mean radius goes to infinity. We have also found the intriguing possibility that the inflation due to the cosmological constant might be prevented by the interaction with the bulk. We show that the problem for the mean radius can be completely solved in our models, which include as particular cases those in the references above.
On the Supersymmetry of Bianchi attractors in Gauged supergravity
Chakrabarty, Bidisha; Samanta, Rickmoy
2016-01-01
Bianchi attractors are near horizon geometries with homogeneous symmetries in the spatial directions. We construct supersymmetric Bianchi attractors in $\\mathcal{N}=2, d=4,5$ gauged supergravity coupled to vector and hypermultiplets. In $d=4$, in the Bianchi I class we construct an electric $1/4$ BPS $AdS_2\\times\\mathbb{R}^2$ geometry. In $d=5$ we consider gauged supergravity with a generic gauging of symmetries of the scalar manifold and the R symmetry. Analyzing the gaugino and hyperino conditions we show that when the fermionic shifts do not vanish there are no supersymmetric Bianchi attractors. When the central charge satisfies an extremization condition, some of the fermionic shifts vanish and supersymmetry requires that the symmetries of the scalar manifold be ungauged. This allows supersymmetric Bianchi attractors sourced by massless gauge fields and a cosmological constant. In the Bianchi I class we show that the anisotropic $AdS_3\\times\\mathbb{R}^2$ solution is $1/2$ BPS. We also construct a new clas...
Falcone, Alfredo; Salvatore, Lisa
2016-09-01
Professor Alfredo Falcone and Dr Lisa Salvatore speak to Roshaine Gunawardana, Managing Commissioning Editor: Professor Alfredo Falcone is the Director of the Department of Oncology and the Specialization School at the University Hospital of Pisa, Italy. He trained in Pisa and Genoa, Italy, and has held major positions in Italian oncology since 2000. He currently has more than 300 publications, including papers in peer-reviewed international and national journals, book chapters, and more than 600 abstracts of presentations to international and national conferences. The majority of his papers regard clinical and translational research, with a particular focus on metastatic colorectal cancer. Dr Lisa Salvatore is a medical oncologist in the Department of Translational Research and New Technologies in Medicine and Surgery at the University of Pisa. She has been an author on about 40 publications in major peer-reviewed publications and has made numerous presentations in national and international conferences. Her main interest is focused on clinical and translational research in metastatic colorectal cancer.
Bianchi-I cosmological model and crossing singularities
Kamenshchik, Alexander Yu.; Pozdeeva, Ekaterina O.; Vernov, Sergey Yu.; Tronconi, Alessandro; Venturi, Giovanni
2017-04-01
We consider a rather simple method for the description of the big bang-big crunch cosmological singularity crossing. For the flat Friedmann universe this method gives the same results as more complicated methods, using Weyl symmetry or the transitions between the Jordan and Einstein frames. It is then easily generalized for the case of a Bianchi-I anisotropic universe. We also present early-time and late-time asymptotic solutions for a Bianchi-I universe, filled with a conformally coupled massless scalar field.
Supersymmetric quantum cosmology for Bianchi class A models
Macías, A; Socorro, J; Macías, Alfredo; Mielke, Eckehard W.; Socorro, José
1998-01-01
The canonical theory of (N=1) supergravity, with a matrix representation for the gravitino covector-spinor, is applied to the Bianchi class A spatially homogeneous cosmologies. The full Lorentz constraint and its implications for the wave function of the universe are analyzed in detail. We found that in this model no physical states other than the trivial "rest frame" type occur.
Bianchi Cosmologies New Variables and a Hidden Supersymmetry
Obregón, O; Ryan, M P; Obregon, Octavio; Pullin, Jorge; Ryan, Michael P.
1993-01-01
We find a supersymmetrization of the Bianchi IX cosmology in terms of Ashtekar's new variables. This provides a framework for connecting the recent results of Graham and those of Ryan and Moncrief for quantum states of this model. These states are also related with the states obtained particularizing supergravity for a minisuperspace. Implications for the general theory are also briefly discussed.
Bianchi type IX string cosmological model in general relativity
Indian Academy of Sciences (India)
Raj Bali; Shuchi Dave
2001-04-01
We have investigated Bianchi type IX string cosmological models in general relativity. To get a determinate solution, we have assumed a condition ρ= i.e. rest energy density for a cloud of strings is equal to the string tension density. The various physical and geometrical aspects of the models are also discussed.
Bianchi type I inﬂationary universe in general relativity
Indian Academy of Sciences (India)
Raj Bali; Vimal Chand Jain
2002-07-01
In this paper, we have investigated Bianchi type I inﬂationary universe in the presence of massless scalar ﬁeld with a ﬂat potential. To get an inﬂationary solution, we have considered a ﬂat region in which potential is constant. The inﬂationary scenario of the model is discussed in detail.
Sifted character sums and free quotients of Bianchi groups
Schlage-Puchta, Jan-Christoph
2011-01-01
We show that the Bianchi group $\\mathrm{PSL}_2(\\mathcal{O}_d)$, where $\\mathcal{O}_d$ is the ring of integers in $\\Q(\\sqrt{d})$, $d<0$, has a free quotient of rank $\\geq |d|^{1/4-\\epsilon}$, as $|d|\\to\\infty$.
Poisson-Lie T-Duality and Bianchi Type Algebras
Jafarizadeh, M A
1999-01-01
All Bianchi bialgebras have been obtained. By introducing a non-degenerate adjoint invariant inner product over these bialgebras the associated Drinfeld doubles have been constructed, then by calculating the coupling matrices for these bialgebras several \\sigma-models with Poisson-Lie symmetry have been obtained. Two simple examples as prototypes of Poisson-Lie dual models have been given.
The Bianchi classification of maximal D=8 gauged supergravities
Bergshoeff, E; Gran, U; Linares, R; Nielsen, M; Ortin, T; Roest, D
2004-01-01
We construct maximal D = 8 gauged supergravities by the reduction of D = 11 supergravity over three-dimensional group manifolds. Such manifolds have been classified by Bianchi. We divide the corresponding gauged supergravities into two classes: class A (with a Lagrangian) and class B (without a Lagr
The Bianchi classification of maximal D = 8 gauged supergravities
Bergshoeff, E.; Gran, U.; Linares, R.; Nielsen, M.; Ortín, T.; Roest, D.
2004-01-01
We construct maximal D = 8 gauged supergravities by the reduction of D = 11 supergravity over three-dimensional group manifolds. Such manifolds have been classified by Bianchi. We divide the corresponding gauged supergravities into two classes: class A (with a Lagrangian) and class B (without a Lagr
Vacuum solutions of Bianchi cosmologies in quadratic gravity
Energy Technology Data Exchange (ETDEWEB)
Deus, Juliano Alves de; Muller, Daniel [Universidade de Brasilia (UnB), DF (Brazil)
2011-07-01
Full text: In this work we solve numerically the vacuum solutions of field equations of Bianchi homogeneous universes in the context of Semiclassical theory. Our interest is to study the quadratic theory of gravity with regard in the cosmological description of our universe in periods of intense fields. Bianchi cosmologies are anisotropic homogeneous cosmological models, but can include the isotropic models as particular cases (Bianchi I, VII and IX include homogeneous and isotropic Friedmann models plane, hyperbolic and spherical, respectively). Homogeneous models are good cosmological representations of our universe. With focus in solutions for intense fields, like the early universe, where isotropy is not necessarily required, the adopted scenario is the vacuum solutions, where the geometry is dominant in determining the gravitation. Still following in this way, the Semiclassical theory, which considers quantum matter fields propagating in classical geometrical background, is addressed to give the field equations. This formalism leads to fourth-order ordinary differential equations, in contrast to second-order equations from General Relativity. The Lagrangian of the theory is quadratic in the Ricci scalar and in the Ricci tensor. The equations system is highly non-linear and can be only numerically solved, except perhaps for few particular cases. We obtained numerical solutions for Bianchi V II{sub A} evolving to Minkowski and to de Sitter solutions, and also to singularities. The both first and second solutions were obtained choosing initial conditions near from respective exact vacuum solutions from Einstein theory, which are also exact solutions of the quadratic theory. Other Bianchi types are still under study. (author)
Bianchi Type-I, V and VIo models in modified generalized scalar–tensor theory
Indian Academy of Sciences (India)
T Singh; R Chaubey
2007-08-01
In modified generalized scalar–tensor (GST) theory, the cosmological term is a function of the scalar field and its derivatives $\\dot{}^{2}$. We obtain exact solutions of the field equations in Bianchi Type-I, V and VIo space–times. The evolution of the scale factor, the scalar field and the cosmological term has been discussed. The Bianchi Type-I model has been discussed in detail. Further, Bianchi Type-V and VIo models can be studied on the lines similar to Bianchi Type-I model.
Bianchi Type I Cosmologies in Arbitrary Dimensional Dilaton Gravities
Chen, C M; Mak, M K; Chen, Chiang-Mei
2000-01-01
We study the low energy string effective action with an exponential type dilaton potential and vanishing torsion in a Bianchi type I space-time geometry. In the Einstein and string frames the general solution of the gravitational field equations can be expressed in an exact parametric form. Depending on the values of some parameters the obtained cosmological models can be generically divided into three classes, leading to both singular and nonsingular behaviors. The effect of the potential on the time evolution of the mean anisotropy parameter is also considered in detail, and it is shown that a Bianchi type I Universe isotropizes only in the presence of a dilaton field potential or a central deficit charge.
Bianchi type I cosmologies in arbitrary dimensional dilaton gravities
Chen, Chiang-Mei; Harko, T.; Mak, M. K.
2000-12-01
We study the low energy string effective action with an exponential type dilaton potential and vanishing torsion in a Bianchi type I space-time geometry. In the Einstein and string frames the general solution of the gravitational field equations can be expressed in an exact parametric form. Depending on the values of the dilaton coupling constant and of the coefficient in the exponential, the obtained cosmological models can be generically divided into three classes, leading to both singular and non-singular behaviors. The effect of the potential on the time evolution of the mean anisotropy parameter is also considered in detail, and it is shown that a Bianchi type I universe isotropizes only in the presence of a dilaton field potential or a central deficit charge.
Bianchi-IX, Darboux-Halphen and Chazy-Ramanujan
Chanda, Sumanto; Roychowdhury, Raju
2015-01-01
Bianchi-IX four metrics are $SU(2)$ invariant solutions of vacuum Einstein equation, for which the connection-wise self-dual case describes the Euler Top, while the curvature-wise self-dual case yields the Ricci flat classical Darboux-Halphen system. It is possible to see such a solution exhibiting Ricci flow. The classical Darboux-Halphen system is a special case of the generalized one that arises from a reduction of the self-dual Yang-Mills equation and the solutions to the related homogeneous quadratic differential equations provide the desired metric. A few integrable and near-integrable dynamical systems related to the Darboux-Halphen system and occur in the study of Bianchi IX gravitational instanton have been listed as well. We explore in details whether self-duality implies integrability.
Bounce behaviour in Kantowski-Sachs and Bianchi cosmologies
Energy Technology Data Exchange (ETDEWEB)
Solomons, Deon [Cape Peninsula University of Technology, Cape Town (South Africa); Dunsby, Peter K S [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa); Ellis, George F R [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)
2006-12-07
Many cosmological scenarios envisage either a bounce of the universe at early times, or collapse of matter locally to form a black hole which re-expands into a new expanding universe region. Energy conditions preclude this happening for ordinary matter in general relativistic universes, but scalar or dilatonic fields can violate some of these conditions, and so could possibly provide bounce behaviour. In this paper we show that such bounces cannot occur in Kantowski-Sachs models without violating the reality condition {phi}-dot{sup 2} {>=}0. This also holds true for other isotropic spatially homogeneous Bianchi models, with the exception of closed Friedmann-Robertson-Walker and Bianchi IX models; bounce behaviour violates the weak energy condition {rho} {>=} 0 and {rho} + p {>=} 0. We turn to the Randall-Sundrum type braneworld scenario for a possible resolution of this problem.
Nonlinear Spinor Fields in Bianchi type-III spacetime
Saha, Bijan
2016-01-01
Within the scope of Bianchi type-III spacetime we study the role of spinor field on the evolution of the Universe as well as the influence of gravity on the spinor field. In doing so we have considered a polynomial type of nonlinearity. In this case the spacetime remains locally rotationally symmetric and anisotropic all the time. It is found that depending on the sign of nonlinearity the models allows both accelerated and oscillatory modes of expansion. The non-diagonal components of energy-momentum tensor though impose some restrictions on metric functions and components of spinor field, unlike Bianchi type I, V and $VI_0$ cases, they do not lead to vanishing mass and nonlinear terms of the spinor field.
Einstein-Bianchi Hyperbolic System for General Relativity
Anderson, A; York, J W; Anderson, Arlen; Choquet-Bruhat, Yvonne; York, James W.
1997-01-01
By employing the Bianchi identities for the Riemann tensor in conjunction with the Einstein equations, we construct a first order symmetric hyperbolic system for the evolution part of the Cauchy problem of general relativity. In this system, the metric evolves at zero speed with respect to observers at rest in a foliation of spacetime by spacelike hypersurfaces while the curvature and connection propagate at the speed of light. The system has no unphysical characteristics, and matter sources can be included.
Statefinder Diagnostic for Dark Energy Models in Bianchi I Universe
Sharif, M
2013-01-01
In this paper, we investigate the statefinder, the deceleration and equation of state parameters when universe is composed of generalized holographic dark energy or generalized Ricci dark energy for Bianchi I universe model. These parameters are found for both interacting as well as non-interacting scenarios of generalized holographic or generalized Ricci dark energy with dark matter and generalized Chaplygin gas. We explore these parameters graphically for different situations. It is concluded that these models represent accelerated expansion of the universe.
Alternative Solutions to Bianchi Type-Ⅰ Cosmology
Institute of Scientific and Technical Information of China (English)
YI Ying; LI Fang-Yu
2007-01-01
@@ We present a class of new exact solutions in string cosmology theory, and the solutions describe a homogeneous but anisotropic plane-symmetric string universe within the framework of Bianchi type-Ⅰ cosmology. Some solutions previously discussed are included in the class of exact solutions as the special cases. Our result may provide further quantitative description and theoretical basis for the string cosmology model.
Characterization of the Lovelock gravity by Bianchi derivative
Indian Academy of Sciences (India)
Naresh Dadhich
2010-06-01
We prove the theorem: The second-order quasilinear differential operator as a second-rank divergence-free tensor in the equation of motion for gravitation could always be derived from the trace of the Bianchi derivative of the fourth-rank tensor, which is a homogeneous polynomial in curvatures. The existence of such a tensor for each term in the polynomial Lagrangian is a new characterization of the Lovelock gravity.
Bianchi type-V string cosmological models in general relativity
Indian Academy of Sciences (India)
Anil Kumar Yadav; Vineet Kumar Yadav; Lallan Yadav
2011-04-01
Bianchi type-V string cosmological models in general relativity are investigated. To get the exact solution of Einstein’s ﬁeld equations, we have taken some scale transformations used by Camci et al [Astrophys. Space Sci. 275, 391 (2001)]. It is shown that Einstein’s ﬁeld equations are solvable for any arbitrary cosmic scale function. Solutions for particular forms of cosmic scale functions are also obtained. Some physical and geometrical aspects of the models are discussed.
Homology and K-theory of the Bianchi groups
Rahm, Alexander D
2011-01-01
We reveal a correspondence between the homological torsion of the Bianchi groups and new geometric invariants, which are effectively computable thanks to their action on hyperbolic space. We use it to explicitly compute their integral group homology and equivariant K-homology. By the Baum/Connes conjecture, which holds for the Bianchi groups, we obtain the K-theory of their reduced C\\ast -algebras in terms of isomorphic images of the computed K-homology. We further find an application to Chen/Ruan orbifold cohomology. Nous mettons en \\'evidence une correspondance entre la torsion homologique des groupes de Bianchi et de nouveaux invariants g\\'eom\\'etriques, calculables gr\\^ace \\'a leur action sur l'espace hyperbolique. Nous l'utilisons pour calculer explicitement leur homologie de groupe \\'a coefficients entiers et leur K-homologie \\'equivariante. En cons\\'equence de la conjecture de Baum/Connes, qui est v\\'erifi\\'ee pour ces groupes, nous obtenons la K-th\\'eorie de leurs C\\ast-alg\\'ebres r\\'eduites en termes...
Directory of Open Access Journals (Sweden)
Valentina Fulginiti
2014-05-01
Full Text Available Being an extreme case of fictitious representation of linguistic otherness, pseudo-translation challenges the idea of a fatal and exclusive link between language and national ethos, a fundamental notion in the Nineteenth-century linguistic and literary culture. The present article compares two emblematic cases of pseudo-translation in post-Unification Italian culture: Luigi Capuana’s hoax Un poeta danese (published in 1882 and the earliest short stories published by Salvatore di Giacomo in 1878, mistakenly considered a plagiarizing translation from an uncredited German original. Their use of pseudo-translation is marked by opposite goals of parody and stylistic imitation; however, both authors challenge the fundamental assumption underlying the notion of «ethnicity of language». Pseudo-translation thus becomes a space of linguistic elaboration, complementary to the author’s direct involvement in translating major European works into Italian (such as Ibsen’s masterpiece A House of Dolls, which Capuana translated in 1891, and Edmond de Goncourt’s novel Sœur Philomèle, which Di Giacomo translated in 1892. Translation thus provides a free space for authors to experiment with new expressive solutions and challenge commonplaces about language and identity: such reflection on the limits of language and nations represent a direct contribution to the linguistic unification of Italy. Caso estremo di rappresentazione fittizia del- l’alterità linguistica, la pseudo-traduzione chiama in causa l’idea del legame unico e “fatale” fra lingua e nazione – concetto fondamentale nella cultura linguistica del XIX secolo. L’articolo mette a confronto due casi emblematici di pseudo-traduzione nella cultura meridionale post-unitaria: la beffa letteraria di Luigi Capuana Un poeta danese (1882 e le ‘tedescherie’ di Salvatore di Giacomo, gruppo di novelle pubblicate nel 1878 che molti considerarono (a torto un plagio da ignoto autore tedesco
Bianchi Type-V universe with a viscous ﬂuid and -term
Indian Academy of Sciences (India)
T Singh; R Chaubey
2007-05-01
We have studied the evolution of a homogeneous, anisotropic universe given by a Bianchi Type-V cosmological model ﬁlled with viscous ﬂuid, in the presence of cosmological constant . The role of viscous ﬂuid and -term in the Bianchi Type-V universe has been studied.
Roy, S. R.; Banerjee, S. K.
1992-11-01
A homogeneous Bianchi type VIh cosmological model filled with perfect fluid, null electromagnetic field and streaming neutrinos is obtained for which the free gravitational field is of the electric type. The barotropic equation of statep = (γ-1)ɛ is imposed in the particular case of Bianchi VI0 string models. Various physical and kinematical properties of the models are discussed.
A dynamical systems approach to the tilted Bianchi models of solvable type
Coley, Alan; Hervik, Sigbjørn
2005-02-01
We use a dynamical systems approach to analyse the tilting spatially homogeneous Bianchi models of solvable type (e.g., types VIh and VIIh) with a perfect fluid and a linear barotropic γ-law equation of state. In particular, we study the late-time behaviour of tilted Bianchi models, with an emphasis on the existence of equilibrium points and their stability properties. We briefly discuss the tilting Bianchi type V models and the late-time asymptotic behaviour of irrotational Bianchi type VII0 models. We prove the important result that for non-inflationary Bianchi type VIIh models vacuum plane-wave solutions are the only future attracting equilibrium points in the Bianchi type VIIh invariant set. We then investigate the dynamics close to the plane-wave solutions in more detail, and discover some new features that arise in the dynamical behaviour of Bianchi cosmologies with the inclusion of tilt. We point out that in a tiny open set of parameter space in the type IV model (the loophole) there exist closed curves which act as attracting limit cycles. More interestingly, in the Bianchi type VIIh models there is a bifurcation in which a set of equilibrium points turns into closed orbits. There is a region in which both sets of closed curves coexist, and it appears that for the type VIIh models in this region the solution curves approach a compact surface which is topologically a torus.
Brehm, Bernhard
2016-01-01
Bianchi models are posited by the BKL picture to be essential building blocks towards an understanding of generic cosmological singularities. We study the behaviour of spatially homogeneous anisotropic vacuum spacetimes of Bianchi type VIII and IX, as they approach the big bang singularity. It is known since 2001 that generic Bianchi IX spacetimes converge towards the so-called Mixmaster attractor as time goes towards the singularity. We extend this result to the case of Bianchi VIII vacuum. The BKL picture suggests that particle horizons should form, i.e. spatially separate regions should causally decouple. We prove that this decoupling indeed occurs, for Lebesgue almost every Bianchi VIII and IX vacuum spacetime.
Bianchi Type Ⅲ String Cosmological Model with Bulk Viscosity
Institute of Scientific and Technical Information of China (English)
WANGXing-Xiang
2004-01-01
The Bianchi type Ⅲ cosmological model for a cloud string with bulk viscosity are presented. To obtain a determinate model, an equation of state ρ=kλ and a relation between metric potentials B = Cn are assumed. The physical and geometric aspects of the model are also discussed. The model describes a shearing non-rotating continuously expanding universe with a big-bang start, and the relation between the coefficient of bulk viscosity and the energy density is ζ∝ρ1/2.
Bianchi Type Ⅲ String Cosmological Model with Bulk Viscosity
Institute of Scientific and Technical Information of China (English)
WANG Xing-Xiang
2004-01-01
The Bianchi type Ⅲ cosmological model for a cloud string with bulk viscosity are presented. To obtaina determinate model, an equation of state p = κλ and a relation between metric potentials B = Cn are assumed. Thephysical and geometric aspects of the model are also discussed. The model describes a shearing non-rotating continuouslyexpanding universe with a big-bang start, and the relation between the coefficient of bulk viscosity and the energy densityis ζ∝1 p1/2.
Bianchi Type-I Universe with wet dark fluid
Indian Academy of Sciences (India)
T Singh; R Chaubey
2008-09-01
The Bianchi Type-I Universe filled with dark energy from a wet dark fluid has been considered. A new equation of state for the dark energy component of the Universe has been used. It is modeled on the equation of state = (ρ − ρ*) which can describe a liquid, for example water. The exact solutions to the corresponding field equations are obtained in quadrature form. The solution for constant deceleration parameter have been studied in detail for both power-law and exponential forms. The cases = 1 and = 0 have also been analysed.
Symbolic Dynamics, Modular Curves, and Bianchi IX Cosmologies
Manin, Yuri I.; Marcolli, Matilde
2015-01-01
It is well known that the so called Bianchi IX spacetimes with SO(3)-symmetry in a neighbourhood of the Big Bang exhibit a chaotic behaviour of typical trajectories in the backward movement of time. This behaviour (Mixmaster Model of the Universe) can be encoded by the shift of two-sided continued fractions. Exactly the same shift encodes the sequences of intersections of hyperbolic geodesics with purely imaginary axis in the upper complex half-plane, that is geodesic flow on an appropriate m...
Stochastic eternal inflation in a Bianchi type I universe
Kohli, Ikjyot Singh; Haslam, Michael C.
2016-01-01
The phenomenon of stochastic eternal inflation is studied for a chaotic inflation potential in a Bianchi type I spacetime background. After deriving the appropriate stochastic Klein-Gordon equation, we give details on the conditions for eternal inflation. It is shown that for eternal inflation to occur, the amount of anisotropy must be small. In fact, it is shown that eternal inflation will only take place if the shear anisotropy variables take on values within a small region of the interior of the Kasner circle. We then calculate the probability of eternal inflation occurring based on techniques from stochastic calculus.
Bianchi's Bäcklund transformation for higher dimensional quadrics
Dincă, Ion I.
2016-12-01
We provide a generalization of Bianchi's Bäcklund transformation from 2-dimensional quadrics to higher dimensional quadrics (which is also a generalization of Tenenblat-Terng's Bäcklund transformation of isometric deformations of Hn(R) in R 2 n - 1 to general quadrics). Our investigation is the higher dimensional version of Bianchi's main three theorems on the theory of isometric deformations of quadrics and Bianchi's treatment of the Bäcklund transformation for diagonal paraboloids via conjugate systems. It became the driving force which led to the flourishing of the classical differential geometry in the second half of the XIX th century and its profound study by illustrious geometers led to interesting results. Today it is still an open problem in its full generality, but basic familiar results like the Gauß-Bonnet fundamental theorem of surfaces and the Codazzi-Mainardi equations (independently discovered also by Peterson) were first communicated to the French Academy of Sciences. A list (most likely incomplete) of the winners of the prize includes Bianchi, Bonnet, Guichard, Weingarten.Up to 1899 isometric deformations of the (pseudo-)sphere and isotropic quadrics without center (from a metric point of view they can be considered as metrically degenerate quadrics without center) together with their Bäcklund transformation and the complementary transformation of isometric deformations of surfaces of revolution were investigated by geometers such as Bäcklund, Bianchi, Bonnet, Darboux, Goursat, Hazzidakis, Lie, Weingarten, etc.In 1899 Guichard discovered that when quadrics with(out) center and of revolution around the focal axis roll on their isometric deformations their foci describe constant mean curvature (minimal) surfaces (and Bianchi proved the converse: all constant mean curvature (minimal) surfaces can be realized in this way).With Guichard's result the race to find the isometric deformations of general quadrics was on; it ended with Bianchi
Stochastic Eternal Inflation in a Bianchi Type I Universe
Kohli, Ikjyot Singh
2015-01-01
In this paper, we analyze a Bianchi Type I model with a scalar field in a chaotic inflation potential, $V(\\phi) = \\frac{1}{2}\\phi^2$ in the context of stochastic eternal inflation. We use the typical slow-roll approximation in combination with expansion-normalized variables in an orthonormal frame approach to obtain a dynamical system which describes the dynamics of the shear anisotropy and the inflaton field. We first show that the dynamics of the inflaton field can be decoupled from the dynamics of the shear anisotropy. We then use a fixed-points analysis in combination with global techniques from topological dynamical systems theory to prove that the cosmological model under consideration isotropizes irrespective of an inflationary epoch, which has also described by other authors who have investigated a Bianchi Type I model under similar configurations. We then show that for inflation to occur, the amount of anisotropy must be very small. We also give a description of the stochastic dynamics of the inflato...
Symbolic Dynamics, Modular Curves, and Bianchi IX Cosmologies
Manin, Yuri
2015-01-01
It is well known that the so called Bianchi IX spacetimes with SO(3)-symmetry in a neighbourhood of the Big Bang exhibit a chaotic behaviour of typical trajectories in the backward movement of time. This behaviour (Mixmaster Model of the Universe) can be encoded by the shift of two-sided continued fractions. Exactly the same shift encodes the sequences of intersections of hyperbolic geodesics with purely imaginary axis in the upper complex half-plane, that is geodesic flow on an appropriate modular surface. A physical interpretation of this coincidence was suggested in arXiv:1402.2158: namely, that Mixmaster chaos is an approximate description of the passage from a hot quantum Universe at the Big Bang moment to the cooling classical Universe. Here we discuss and elaborate this suggestion, looking at the Mixmaster Model from the perspective of the second class of Bianchi IX spacetimes: those with SU(2)-symmetry (self-dual Einstein metrics). We also extend it to the more general context related to Painleve' VI ...
Bianchi Type-I cosmological mesonic stiff fluid models in Lyra's geometry
Indian Academy of Sciences (India)
S D Katore; S V Thakare; K S Adhao
2008-07-01
Bianchi Type-I cosmological models in Lyra's geometry are obtained when the source of gravitational field is a perfect fluid coupled with massless mesonic scalar field. Some physical and kinematical properties of the models are also discussed.
On the Asserted Clash between the Freud and the Bianchi Identities
Antoci, S
1995-01-01
Through a constructive method it is shown that the claim advanced in recent times about a clash that should occur between the Freud and the Bianchi identities in Einstein's general theory of relativity is based on a faulty argument.
On the asserted clash between the Freud and the Bianchi identities
Antoci, S.
1995-09-01
Through a constructive method it is shown that the claim advanced in recent times about a clash that should occur between the Freud and the Bianchi identities in Einstein's general theory of relativity is based on a faulty argument.
$\\psi$ = W e$^{\\pm\\phi}$ quantum cosmological solutions for Class A Bianchi models
Obregón, O
1995-01-01
We find solutions for quantum Class A Bianchi models of the form \\rm \\Psi=W\\, e^{\\pm \\Phi} generalizing the results obtained by Moncrief and Ryan in standard quantum cosmology. For the II and IX Bianchi models there are other solutions \\rm \\tilde\\Phi_2, \\rm \\tilde\\Phi_9 to the Hamilton-Jacobi equation for which \\rm \\Psi is necessarely zero, in contrast with solutions found in supersymmetric quantum cosmology.
Bianchi Type-V model with a perfect fluid and -term
Indian Academy of Sciences (India)
T Singh; R Chaubey
2006-09-01
A self-consistent system of gravitational field with a binary mixture of perfect fluid and dark energy given by a cosmological constant has been considered in Bianchi Type-V universe. The perfect fluid is chosen to be obeying either the equation of state = ρ with ∈ [0, 1] or a van der Waals equation of state. The role of -term in the evolution of the Bianchi Type-V universe has been studied.
Nonlinear Spinor Fields in Bianchi type-V spacetime
Saha, Bijan
2016-01-01
A self-consistent system of nonlinear spinor and Bianchi type-V anisotropic gravitational fields are investigated. It is found that the presence of nontrivial non-diagonal components of the energy-momentum tensor of the spinor field imposes some severe restrictions to the system. As a result two different solutions are found. In one case the metric functions are similar to each other, i.e., $a_1 \\sim a_2 \\sim a_3$ and the spinor mass and spinor field nonlinearity do not disappear from the system. In this case the spacetime expands with acceleration in case of a positive self-coupling constant $\\lambda$. A negative $\\lambda$ gives rise to a cyclic or periodical mode of expansion. In the second case the spinor mass and the spinor field nonlinearity vanish and the Universe expands linearly with time.
Classical Bianchi type I cosmology in K-essence theory
Socorro, J; Espinoza-García, Abraham
2014-01-01
We use one of the simplest forms of the K-essence theory and we apply it to the classical anisotropic Bianchi type I cosmological model, with a barotropic perfect fluid modeling the usual matter content and with cosmological constant. The classical solutions for any but the stiff fluid and without cosmological constant are found in closed form, using a time transformation. We also present the solution whith cosmological constant and some particular values of the barotropic parameter. We present the possible isotropization of the cosmological model, using the ratio between the anisotropic parameters and the volume of the universe and show that this tend to a constant or to zero for different cases. We include also a qualitative analysis of the analog of the Friedmann equation.
Geodesic-light-cone coordinates and the Bianchi I spacetime
Fleury, Pierre; Fanizza, Giuseppe
2016-01-01
The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose a detailed, pedagogical, and rigorous introduction to this coordinate system, explore its gauge degrees of freedom, and emphasize its interest when geometric optics is at stake. We then apply the GLC formalism to the homogeneous and anisotropic Bianchi I cosmology. More than a simple illustration, this application (i) allows us to show that the Weinberg conjecture according to which gravitational lensing does not affect the proper area of constant-redshift surfaces is significantly violated in a globally anisotropic universe; and (ii) offers a glimpse into new ways to constrain cosmic isotropy from the Hubble diagram.
Geodesic-light-cone coordinates and the Bianchi I spacetime
Fleury, Pierre; Nugier, Fabien; Fanizza, Giuseppe
2016-06-01
The geodesic-light-cone (GLC) coordinates are a useful tool to analyse light propagation and observations in cosmological models. In this article, we propose a detailed, pedagogical, and rigorous introduction to this coordinate system, explore its gauge degrees of freedom, and emphasize its interest when geometric optics is at stake. We then apply the GLC formalism to the homogeneous and anisotropic Bianchi I cosmology. More than a simple illustration, this application (i) allows us to show that the Weinberg conjecture according to which gravitational lensing does not affect the proper area of constant-redshift surfaces is significantly violated in a globally anisotropic universe; and (ii) offers a glimpse into new ways to constrain cosmic isotropy from the Hubble diagram.
A quantum gravitational inflationary scenario in Bianchi-I spacetime
Gupt, Brajesh
2013-01-01
We investigate the $\\phi^2$ inflationary model in the Bianchi-I spacetime using effective spacetime description of loop quantum cosmology to understand the issues of the resolution of initial singularity, isotropization, effect of anisotropies on amount of inflation, and the phase space attractors in the presence of non-perturbative quantum gravitational modifications. A comparative analysis with the classical theory by including more general initial conditions than the ones previously considered in the latter is also performed. We show that, in general, the classical singularity is replaced by a bounce of the mean scale factor in loop quantum cosmology. Due to the underlying quantum geometric effects, the energy density of the inflaton and the anisotropic shear remain bounded throughout the non-singular evolution. Starting from arbitrary anisotropic initial conditions, a loop quantum universe isotropizes either before or soon after the onset of slow-roll inflation. We find a double attractor behavior in the ...
Gauged supergravities from Bianchi's group manifolds
Energy Technology Data Exchange (ETDEWEB)
Bergshoeff, Eric [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Gran, Ulf [Department of Mathematics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Linares, Roman [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, AP 55-534, Mexico, DF, cp 09340 (Mexico); Nielsen, Mikkel [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); OrtIn, Tomas [Instituto de FIsica Teorica, C-XVI, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Roest, Diederik [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)
2004-05-21
We construct maximal D = 8 gauged supergravities by the reduction of D 11 supergravity over three-dimensional group manifolds. Such manifolds are classified into two classes, A and B, and eleven types. This Bianchi classification carries over to the gauged supergravities. The class A theories have 1/2 BPS domain wall solutions that uplift to purely gravitational solutions consisting of 7D Minkowski and a 4D Euclidean geometry. These geometries are generically singular. The two regular exceptions correspond to the near-horizon limit of the single- or double-centre Kaluza-Klein monopole. In contrast, the class B supergravities are defined by a set of equations of motion that cannot be integrated to an action and allow for no 1/2 BPS domain walls.
Total energy of the Bianchi type I universes
Xulu, S S
2000-01-01
Using the symmetric energy-momentum complexes of Landau and Lifshitz, Papapetrou, and Weinberg we obtain the energy of the universe in anisotropic Bianchi type I cosmological models . The energy (due to matter plus field) is found to be zero and this agrees with a previous result of Banerjee and Sen who investigated this problem using the Einstein energy-momentum complex. Our result supports the importance of the energy-momentum complexes and contradicts the prevailing ``folklore'' that different energy-momentum complexes could give different and hence unacceptable energy distribution in a given space-time. The result that the total energy of the universe in these models is zero supports the viewpoint of Tryon. Rosen computed the total energy of the closed homogeneous isotropic universe and found that to be zero, which agrees with the studies of Tryon.
Camci, U; Oz, I Basaran
2016-01-01
The Noether symmetry approach is useful tool to restrict the arbitrariness in a gravity theory when the equations of motion are underdetermined due to the high number of functions to be determined in the ansatz. We consider two scalar-coupled theories of gravity, one motivated by induced gravity, the other more standard; in Bianchi I, Bianchi III and Kantowski-Sachs cosmological models. For these models, we present a full set of Noether gauge symmetries, which are more general than those obtained by the strict Noether symmetry approach in our recent work. Some exact solutions are derived using the first integrals corresponding to the obtained Noether gauge symmetries.
Iizuka, Norihiro; Maeda, Kengo
2014-01-01
Bianchi black branes (black brane solutions with homogeneous but anisotropic horizons classified by the Bianchi type) provide a simple holographic setting with lattice structures taken into account. In the case of holographic superconductor, we have a persistent current with lattices. Accordingly, we expect that in the dual gravity side, a black brane should carry some momentum along a direction of lattice structure, where translational invariance is broken. Motivated by this expectation, we consider whether---and if possible, in what circumstances---a Bianchi black brane can have momentum along a direction of no-translational invariance. First, we show that this {\\it cannot} be the case for a certain class of stationary Bianchi black brane solutions in the Einstein-Maxwell-dilation theory. Then we also show that this {\\it can} be the case for some Bianchi VII$_0$ black branes by numerically constructing such a solution in the Einstein-Maxwell theory with an additional vector field having a source term. The h...
Bianchi Type VI1 Viscous Fluid Cosmological Model in Wesson´s Theory of Gravitation
Khadekar, G. S.; Avachar, G. R.
2007-03-01
Field equations of a scale invariant theory of gravitation proposed by Wesson [1, 2] are obtained in the presence of viscous fluid with the aid of Bianchi type VIh space-time with the time dependent gauge function (Dirac gauge). It is found that Bianchi type VIh (h = 1) space-time with viscous fluid is feasible in this theory, whereas Bianchi type VIh (h = -1, 0) space-times are not feasible in this theory, even in the presence of viscosity. For the feasible case, by assuming a relation connecting viscosity and metric coefficient, we have obtained a nonsingular-radiating model. We have discussed some physical and kinematical properties of the models.
Loop quantum cosmology of Bianchi IX: Inclusion of inverse triad corrections
Corichi, Alejandro; Karami, Asieh
2016-06-01
We consider the loop quantization of the (diagonal) Bianchi type IX cosmological model. We explore different quantization prescriptions that extend the work of Wilson-Ewing and Singh. In particular, we study two different ways of implementing the so-called inverse triad corrections. We construct the corresponding Hamiltonian constraint operators and show that the singularity is formally resolved. We find the effective equations associated with the different quantization prescriptions, and study the relation with the isotropic k = 1 model that, classically, is contained within the Bianchi IX model. Somewhat surprisingly, we find the most natural quantization does not reduce to the k = 1 model. We use geometrically defined scalar observables to explore the physical implications of each of these theories. This is the first part in a series of papers analyzing different aspects of the Bianchi IX model, with inverse corrections, within loop quantum cosmology (LQC).
Energy distributions of Bianchi type-VI h Universe in general relativity and teleparallel gravity
Özkurt, Şeref; Aygün, Sezg&idot; n.
2017-04-01
In this paper, we have investigated the energy and momentum density distributions for the inhomogeneous generalizations of homogeneous Bianchi type-VI h metric with Einstein, Bergmann-Thomson, Landau-Lifshitz, Papapetrou, Tolman and Møller prescriptions in general relativity (GR) and teleparallel gravity (TG). We have found exactly the same results for Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum distributions in Bianchi type-VI h metric for different gravitation theories. The energy-momentum distributions of the Bianchi type- VI h metric are found to be zero for h = -1 in GR and TG. However, our results agree with Tripathy et al, Tryon, Rosen and Aygün et al.
Khan, Suhail; Khan, Gulzar Ali
2016-01-01
The aim of this paper is to explore teleparallel conformal Killing vector fields (CKVFs) of locally rotationally symmetric (LRS) Bianchi type V spacetimes in the context of teleparallel gravity and compare the obtained results with those of general relativity. The general solution of teleparallel conformal Killing's equations is found in terms of some unknown functions of t and x , along with a set of integrability conditions. The integrability conditions are solved in some particular cases to get the final form of teleparallel CKVFs. It is observed that the LRS Bianchi type V spacetimes admit proper teleparallel CKVF in only one case, while in remaining cases the teleparallel CKVFs reduce to teleparallel Killing vector fields (KVFs). Moreover, it is shown that the LRS Bianchi type V spacetimes do not admit any proper teleparallel homothetic vector field (HVF).
Khan, Suhail; Hussain, Tahir; Khan, Gulzar Ali
The aim of this paper is to explore teleparallel conformal Killing vector fields (CKVFs) of locally rotationally symmetric (LRS) Bianchi type V spacetimes in the context of teleparallel gravity and compare the obtained results with those of general relativity (GR). The general solution of teleparallel conformal Killing's equations is found in terms of some unknown functions of t and x, along with a set of integrability conditions. The integrability conditions are solved in some particular cases to get the final form of teleparallel CKVFs. It is observed that the LRS Bianchi type V spacetimes admit proper teleparallel CKVF in only one case, while in remaining cases the teleparallel CKVFs reduce to teleparallel Killing vector fields (KVFs). Moreover, it is shown that the LRS Bianchi type V spacetimes do not admit any proper teleparallel homothetic vector field (HVF).
Indian Academy of Sciences (India)
SEREF ÖZKURT; SEZGIN AYGÜN
2017-04-01
In this paper, we have investigated the energy and momentum density distributions for the inhomogeneous generalizations of homogeneous Bianchi type-$VI_{h}$ metric with Einstein, Bergmann–Thomson, Landau–Lifshitz,Papapetrou, Tolman and M$\\phi$ller prescriptions in general relativity (GR) and teleparallel gravity (TG). We have found exactly the same results for Einstein, Bergmann–Thomson and Landau–Lifshitz energy–momentum distributions in Bianchi type-$VI_{h}$ metric for different gravitation theories. The energy–momentum distributions of the Bianchi type-$VI_{h}$ metric are found to be zero for $h$ = −1 in GR and TG. However, our results agree with Tripathy et al, Tryon, Rosen and Aygün et al.
Loop quantum cosmology of Bianchi IX: Inclusion of inverse triad corrections
Corichi, Alejandro
2016-01-01
We consider the loop quantization of the (diagonal) Bianchi type IX cosmological model. We explore different quantization prescriptions that extend the work of Wilson-Ewing and Singh. In particular, we study two different ways of implementing the so-called inverse triad corrections. We construct the corresponding Hamiltonian constraint operators and show that the singularity is formally resolved. We find the effective equations associated with the different quantization prescriptions, and study the relation with the isotropic $k$=1 model that, classically, is contained within the Bianchi IX model. We use geometrically defined scalar observables to explore the physical implications of each of these theories. This is the first part in a series of papers analyzing different aspects of the Bianchi IX model, with inverse corrections, within loop quantum cosmology.
Homoclinic Chaos in Axisymmetric Bianchi-IX cosmological models with an "ad hoc" quantum potential
Corrêa, G. C.; Stuchi, T. J.; Jorás, S. E.
2010-01-01
In this work we study the dynamics of the axisymmetric Bianchi IX cosmological model with a term of quantum potential added. As it is well known this class of Bianchi IX models are homogeneous and anisotropic with two scale factors, $A(t)$ and $B(t)$, derived from the solution of Einstein's equation for General Relativity. The model we use in this work has a cosmological constant and the matter content is dust. To this model we add a quantum-inspired potential that is intended to represent sh...
Physical Aspects of Unitary evolution of Bianchi-I Quantum Cosmological Model
Pal, Sridip
2015-01-01
In this work, we study some physical aspects of unitary evolution of Bianchi-I model. In particular, we study the behavior of the volume and the scale factor as a function of time for the Bianchi-I universe with ultra-relativistic fluid ($\\alpha=1$). The expectation value of volume is shown not to hit any singularity. We elucidate on the anisotropic nature of the solution and physically interpret the wavefunction as a superposition of collapsing universe and expanding universe mimicking Hartle-Hawking type wavefunction. The same analysis has been done for $\\alpha\
Bianchi type-I, type-III and Kantowski-Sachs solutions in f( T) gravity
Rodrigues, M. E.; Kpadonou, A. V.; Rahaman, F.; Oliveira, P. J.; Houndjo, M. J. S.
2015-06-01
In the context of modified tele-parallel theory of gravity, we undertake cosmological anisotropic models and search for their solutions. Within a suitable choice of non-diagonal tetrads, the decoupled equations of motion are obtained for Bianchi-I, Bianchi-III and Kantowski-Sachs models, from which we obtain the correspondent solutions. By the way, energy density and pressures are also obtained, showing, as an important result, that our universe may live a quintessence like universe even while anisotropic models are considered.
Locally rotationally symmetric Bianchi type I cosmology in f(R, T) gravity
Energy Technology Data Exchange (ETDEWEB)
Shamir, M.F. [National University of Computer and Emerging Sciences, Department of Sciences and Humanities, Lahore (Pakistan)
2015-08-15
This manuscript is devoted to the investigation of the Bianchi type I universe in the context of f(R, T) gravity. For this purpose, we explore the exact solutions of locally rotationally symmetric Bianchi type I spacetime. The modified field equations are solved by assuming an expansion scalar θ proportional to the shear scalar σ, which gives A = B{sup n}, where A, B are the metric coefficients and n is an arbitrary constant. In particular, three solutions have been found and physical quantities are calculated in each case. (orig.)
Imparting small vorticity to a Bianchi type-VIh empty spacetime
Batakis, Nikos A.
1981-04-01
We present and briefly discuss a Bianchi type-VIh empty spacetime. The field equations have been solved after being linearized with respect to a parameter which imparts vorticity to the model. The limit of zero vorticity is an already known solution.
Late-time behaviour of the tilted Bianchi type VIh models
Hervik, S.; van den Hoogen, R. J.; Lim, W. C.; Coley, A. A.
2007-08-01
We study tilted perfect fluid cosmological models with a constant equation of state parameter in spatially homogeneous models of Bianchi type VIh using dynamical systems methods and numerical experimentation, with an emphasis on their future asymptotic evolution. We determine all of the equilibrium points of the type VIh state space (which correspond to exact self-similar solutions of the Einstein equations, some of which are new), and their stability is investigated. We find that there are vacuum plane-wave solutions that act as future attractors. In the parameter space, a 'loophole' is shown to exist in which there are no stable equilibrium points. We then show that a Hopf-bifurcation can occur resulting in a stable closed orbit (which we refer to as the Mussel attractor) corresponding to points both inside the loophole and points just outside the loophole; in the former case the closed curves act as late-time attractors while in the latter case these attracting curves will co-exist with attracting equilibrium points. In the special Bianchi type III case, centre manifold theory is required to determine the future attractors. Comprehensive numerical experiments are carried out to complement and confirm the analytical results presented. We note that the Bianchi type VIh case is of particular interest in that it contains many different subcases which exhibit many of the different possible future asymptotic behaviours of Bianchi cosmological models.
Inhomogeneous generalizations of Bianchi Type VIh universes with stiff perfect fluid and radiation
Roy, S. R.; Prasad, A.
1995-03-01
Families of inhomogeneous models filled with a stiff perfect fluid and radiation have been derived in which there is no flow of total momentum. The models are generalizations of those of Bianchi Type VIh and are discussed for some particular forms of the arbitrary functions appearing in them.
Quark matter coupled to domain walls in Bianchi types II, VIII and IX Universes
Indian Academy of Sciences (India)
S D Katore; M M Sancheti; S P Hatkar
2014-10-01
In this study of Bianchi types II, VIII and IX Universes, quark matter coupled to domain walls in the context of general relativity are explored. To obtain deterministic solution of the Einstein’s field equations, various techniques are adopted. The features of the obtained solution are discussed.
Bianchi Type I Cosmological Models in Eddington-inspired Born–Infeld Gravity
Directory of Open Access Journals (Sweden)
Tiberiu Harko
2014-10-01
Full Text Available We consider the dynamics of a barotropic cosmological fluid in an anisotropic, Bianchi type I space-time in Eddington-inspired Born–Infeld (EiBI gravity. By assuming isotropic pressure distribution, we obtain the general solution of the field equations in an exact parametric form. The behavior of the geometric and thermodynamic parameters of the Bianchi type I Universe is studied, by using both analytical and numerical methods, for some classes of high density matter, described by the stiff causal, radiation, and pressureless fluid equations of state. In all cases the study of the models with different equations of state can be reduced to the integration of a highly nonlinear second order ordinary differential equation for the energy density. The time evolution of the anisotropic Bianchi type I Universe strongly depends on the initial values of the energy density and of the Hubble function. An important observational parameter, the mean anisotropy parameter, is also studied in detail, and we show that for the dust filled Universe the cosmological evolution always ends into isotropic phase, while for high density matter filled universes the isotropization of Bianchi type I universes is essentially determined by the initial conditions of the energy density.
On Bianchi-I cosmic strings coupled with Maxwell ﬁelds in bimetric relativity
Indian Academy of Sciences (India)
V Mahurpawar; S D Deo
2003-10-01
Axially symmetric Bianchi-I model is studied with source cosmic cloud strings coupled with electromagnetic ﬁeld in Rosen’s bimetric theory of relativity and observed that there is no contribution from cosmic strings and Maxwell ﬁelds in this theory.
Tilted Bianchi type I dust ﬂuid cosmological model in general relativity
Indian Academy of Sciences (India)
Raj Bali; Keshav Sharma
2002-03-01
In this paper, we have investigated a tilted Bianchi type I cosmological model ﬁlled with dust of perfect ﬂuid in general relativity. To get a determinate solution, we have assumed a condition = between metric potentials. The physical and geometrical aspects of the model together with singularity in the model are also discussed.
Bianchi Type-IX viscous fluid cosmological model in general relativity
Indian Academy of Sciences (India)
Raj Bali; Mahesh Kumar Yadav
2005-02-01
Bianchi Type-IX viscous fluid cosmological model is investigated. To get a deterministic model, we have assumed the condition = ( is a constant) between metric potentials and where is the coefficient of shear viscosity and the scalar of expansion in the model. The coefficient of bulk viscosity () is taken as constant. The physical and geometrical aspects of the model are also discussed.
A higher-dimensional Bianchi type-I inﬂationary Universe in general relativity
Indian Academy of Sciences (India)
S D Katore; K S Adhav; V G Mete; A Y Shaikh
2012-01-01
A ﬁve-dimensional Bianchi type-I inﬂationary Universe is investigated in the presence of massless scalar ﬁeld with a ﬂat potential. To get an inﬂationary Universe, a ﬂat region in which the potential is constant is considered. Some physical and kinematical properties of the Universe are also discussed.
Interpolating from Bianchi attractors to Lifshitz and AdS spacetimes
Energy Technology Data Exchange (ETDEWEB)
Kachru, Shamit [SITP, Department of Physics and Theory Group, SLAC, Stanford University,Stanford, CA 94305 (United States); Kundu, Nilay [Tata Institute for Fundamental Research, Mumbai 400005 (India); Saha, Arpan [Indian Institute of Technology - Bombay,Powai, Mumbai (India); Samanta, Rickmoy; Trivedi, Sandip P. [Tata Institute for Fundamental Research, Mumbai 400005 (India)
2014-03-17
We construct classes of smooth metrics which interpolate from Bianchi attractor geometries of Types II, III, VI and IX in the IR to Lifshitz or AdS{sub 2}×S{sup 3} geometries in the UV. While we do not obtain these metrics as solutions of Einstein gravity coupled to a simple matter field theory, we show that the matter sector stress-energy required to support these geometries (via the Einstein equations) does satisfy the weak, and therefore also the null, energy condition. Since Lifshitz or AdS{sub 2}×S{sup 3} geometries can in turn be connected to AdS{sub 5} spacetime, our results show that there is no barrier, at least at the level of the energy conditions, for solutions to arise connecting these Bianchi attractor geometries to AdS{sub 5} spacetime. The asymptotic AdS{sub 5} spacetime has no non-normalizable metric deformation turned on, which suggests that furthermore, the Bianchi attractor geometries can be the IR geometries dual to field theories living in flat space, with the breaking of symmetries being either spontaneous or due to sources for other fields. Finally, we show that for a large class of flows which connect two Bianchi attractors, a C-function can be defined which is monotonically decreasing from the UV to the IR as long as the null energy condition is satisfied. However, except for special examples of Bianchi attractors (including AdS space), this function does not attain a finite and non-vanishing constant value at the end points.
Vaselli, Orlando; Nisi, Barbara; Rappuoli, Daniele; Cabassi, Jacopo; Tassi, Franco
2017-04-15
Mercury has a strong environmental impact since both its organic and inorganic forms are toxic, and it represents a pollutant of global concern. Liquid Hg is highly volatile and can be released during natural and anthropogenic processes in the hydrosphere, biosphere and atmosphere. In this study, the distribution of Gaseous Elemental Mercury (GEM) and the total and leached mercury concentrations on paint, plaster, roof tiles, concrete, metals, dust and wood structures were determined in the main buildings and structures of the former Hg-mining area of Abbadia San Salvatore (Siena, Central Italy). The mining complex (divided into seven units) covers a surface of about 65 ha and contains mining structures and managers' and workers' buildings. Nine surveys of GEM measurements were carried out from July 2011 to August 2015 for the buildings and structures located in Units 2, 3 and 6, the latter being the area where liquid mercury was produced. Measurements were also performed in February, April, July, September and December 2016 in the edifices and mining structures of Unit 6. GEM concentrations showed a strong variability in time and space mostly depending on ambient temperature and the operational activities that were carried out in each building. The Unit 2 surveys carried out in the hotter period (from June to September) showed GEM concentrations up to 27,500 ng·m(-3), while in Unit 6, they were on average much higher, and occasionally, they saturated the GEM measurement device (>50,000 ng·m(-3)). Concentrations of total (in mg·kg(-1)) and leached (in μg·L(-1)) mercury measured in different building materials (up to 46,580 mg·kg(-1) and 4470 mg·L(-1), respectively) were highly variable, being related to the edifice or mining structure from which they were collected. The results obtained in this study are of relevant interest for operational cleanings to be carried out during reclamation activities.
Exact solutions of the Bianchi types V and IX via time-dependent quasi-Maxwell equations
Yavari, Morteza
2014-02-01
The exact solutions of the Einstein field equations for the Bianchi types V and IX in presence of a perfect fluid via the time-dependent quasi-Maxwell (TQM) equations are investigated by using the threading formalism.
The decoupling of scalar-modes from a linearly perturbed dust-filled Bianchi type I model
Osano, Bob
2015-01-01
We study linear perturbations about a dust filled Bianchi Type I model with the vorticity set to zero. In comparison to linear perturbations about FLRW models, modes of perturbations about Bianchi type I models are coupled. We find that the tensor that represents the background shear needs to be degenerate in order for the scalar-mode perturbations to decouple from the rest of the flow.
A note on tilted Bianchi type VIh models: the type III bifurcation
Coley, A. A.; Hervik, S.
2008-10-01
In this note we complete the analysis of Hervik, van den Hoogen, Lim and Coley (2007 Class. Quantum Grav. 24 3859) of the late-time behaviour of tilted perfect fluid Bianchi type III models. We consider models with dust, and perfect fluids stiffer than dust, and eludicate the late-time behaviour by studying the centre manifold which dominates the behaviour of the model at late times. In the dust case, this centre manifold is three-dimensional and can be considered a double bifurcation as the two parameters (h and γ) of the type VIh model are varied. We therefore complete the analysis of the late-time behaviour of tilted ever-expanding Bianchi models of types I VIII.
Socorro, J.; Toledo Sesma, L.
2016-03-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus without the contributions of fluxes as first approximation. This approach is applied to anisotropic cosmological Bianchi type II model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Also, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology and we claim that these quantum solution are generic in the moduli scalar field for all Bianchi Class A models. Also we give the relation to these solutions for asymptotic behavior to large argument in the corresponding quantum solution in the gravitational variables and compare with Bohm's solutions, finding that this corresponds to the lowest-order WKB approximation.
Anisotropic Bianchi-I universe with phantom field and cosmological constant
Indian Academy of Sciences (India)
Bikash Chandra Paul; Dilip Paul
2008-12-01
We study an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the universe transits to an isotropic flat FRW universe accommodating the present acceleration. A class of new cosmological solutions is obtained for an anisotropic universe in case an initial anisotropy exists which is bigger than the value determined by the parameter of the kinetic part of the field. Later, an autonomous system of equations for an axially symmetric Bianchi-I universe with phantom field in an exponential potential is studied. We discuss the stability of the cosmological solutions.
Bianchi Type-I String Cosmological Model with Bulk Viscosity and Time-Dependent A term
Institute of Scientific and Technical Information of China (English)
R.K.Tiwari; S.Sharma
2011-01-01
Einstein Geld equations with the cosmological constant is considered in the presence of bulk viscosity in a Bianchi type-I universe. Solutions of the field equations are obtained by assuming the following conditions: the bulk viscosity is proportional to the expansion scalar ￡ oc 0; the expansion scalar is proportional to shear scalar 6 oc cr; and A is proportional to the Hubble parameter A on H. The corresponding interpretations of the cosmological solutions are also discussed.%@@ Einstein field equations with the cosmological constant is considered in the presence of bulk viscosity in a Bianchi type-I universe.Solutions of the field equations are obtained by assuming the following conditions:the bulk viscosity is proportional to the expansion scalar ξ∝θ;the expansion scalar is proportional to shear scalar θ∝σ;and ∧ is proportional to the Hubble parameter ∧∝ H.The corresponding interpretations of the cosmological solutions are also discussed.
The Momentum 4-Vector in Bulk Viscous Bianchi Type-V Space-time
Aydogdu, O; Aydogdu, Oktay; Salti, Mustafa
2006-01-01
Using the Einstein and Bergmann-Thomson prescriptions, the energy and momentum distributions for the Bianchi type-V bulk viscous space-time are evaluated in both general relativity and the teleparallel gravity (the tetrad theory of gravity). It is shown that for the Bianchi type-V bulk viscous solution, the energy and momentum due to matter and fields including gravity are the same in both the methods used. This paper indicates an important point that these energy-momentum definitions agree with each other not only in general relativity but also in teleparallel gravity and sustains the results obtained by some physicist who show that the energy-momentum definitions of Einstein, Landau-Lifshitz, Papapetrou, Weinberg, Penrose and Bergmann-Thomson complexes give the same energy expression in general relativity.
Energy of the Universe in Bianchi-type I Models in Moller's Tetrad Theory of Gravity
Aydogdu, O; Aydogdu, Oktay; Salti, Mustafa
2005-01-01
In this paper, using the energy definition in Moller's tetrad theory of gravity we calculate the total energy of the universe in Bianchi-type I cosmological models which includes both the matter and gravitational fields. The total energy is found to be zero and this result agrees with a previous works of Banerjee-Sen who investigated this problem using the general relativity version of the Einstein energy-momentum complex and Xulu who investigated same problem using the general relativity versions of the Landau-lifshitz, Papapetrou and Weinberg's energy-momentum complexes. The result that total energy of the universe in Bianchi-type I universes is zero supports the viewpoint of Tryon.
On the Energy Momentum in Bianchi Type I-III-V-VI0 Space-Time
Aygun, S; Tarhan, I; Aygun, Melis; Aygun, Sezgin; Tarhan, Ismail
2006-01-01
In this study, using the energy momentum definitions of Einstein, Moller, Bergmann-Thomson, Landau-Lifshitz and Papapetrou we compute the total energy-momentum distribution (due to matter and fields including gravitation) of the universe based on general Bianchi type I-III-V-VI(o) space-time and its transforms type I, III, V, VI(o) metrics, respectively. The energy-momentum densities are found exactly same for Einstein and Bergmann-Thomson definitions. The total energy and momentum is found to be zero for Bianchi types I and VI(o) space-times. These results are same as a previous works of Radinschi, Banerjee-Sen, Xulu and Aydogdu-Salti. Another point is that our study agree with previous works of Cooperstock-Israelit, Rosen, Johri et al.
Directory of Open Access Journals (Sweden)
L. Toledo Sesma
2016-01-01
Full Text Available We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW equation in the context of standard quantum cosmology.
A Qualitative Analysis of The Bianchi Type IV Viscous Fluid Model
Kohli, Ikjyot Singh
2012-01-01
We are interested in formulating a viscous model of the universe based on The Bianchi Type IV algebra. We first begin by considering a congruence of fluid lines in spacetime, upon which, analyzing their propagation behaviour, we derive the famous Raychaudhuri equation, but, in the context of viscous fluids. We will then go through in great detail the topological and algebraic structure of a Bianchi Type IV algebra, by which we will derive the corresponding structure and constraint equations. From this, we will look at The Einstein field equations in the context of orthonormal frames, and derive the resulting dynamical equations: The Raychaudhuri Equation, generalized Friedmann equation, shear propagation equations, and a set of non-trivial constraint equations. We show that for cases in which the bulk viscous pressure is significantly larger than the shear viscosity, this cosmological model isotropizes asymptotically.
Socorro, J
2015-01-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus without the contributions of fluxes as first approximation. This approach is applied to anisotropic cosmological Bianchi type II model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Also, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology and we claim that these quantum solution are generic in the moduli scalar field for all Bianchi Class A models. Also we gives the relation to these solutions for asymptotic behavior to large argument in the corresponding quantum solution in the gravitational variables and is compared with the Bohm's solutions, finding that this corresponds to lowest-order WKB approximation.
Holographic fermions at strong translational symmetry breaking: a Bianchi-VII case study
Bagrov, A; Krikun, A; Schalm, K; Zaanen, J
2016-01-01
It is presently unknown how strong lattice potentials influence the fermion spectral function of the holographic strange metals predicted by the AdS/CFT correspondence. This embodies a crucial test for the application of holography to condensed matter experiments. We show that for one particular momentum direction this spectrum can be computed for arbitrary strength of the effective translational symmetry breaking potential of the so-called Bianchi-VII geometry employing ordinary differential equations. Deep in the strange metal regime we find rather small changes to the single-fermion response computed by the emergent quantum critical IR, even when the potential becomes relevant in the infra-red. However, in the regime where holographic quasi-particles occur, defining a Fermi surface in the continuum, they acquire a finite lifetime at any finite potential strength. At the transition from irrelevancy to relevancy of the Bianchi potential in the deep infra-red the quasi-particle remnants disappear completely a...
Classical dynamics of the Bianchi IX model: space-like and time-like singularity cases
Parnovsky, S L
2016-01-01
We present the comparison of the dynamics of the vacuum Bianchi IX model near the space-like and time-like singularities. In both cases there exist oscillatory type solutions with diverging asymptotically curvature invariants. The dynamics of the time-like singularity case includes additionally the singular solutions with diverging volume density, but vanishing curvature invariants. Our numerical results are consistent with qualitative analytical considerations underlying finding the generic singular solutions to general relativity.
Self-dual gravitational instantons and geometric flows of all Bianchi types
Petropoulos, P M; Siampos, K
2011-01-01
We investigate four-dimensional, self-dual gravitational instantons endowed with a product structure RxM_3, where M_3 is homogeneous of Bianchi type. We analyze the general conditions under which Euclidean-time evolution in the gravitational instanton can be identified with a geometric flow of a metric on M_3. This includes both unimodular and non-unimodular groups, and the corresponding geometric flow is a general Ricci plus Yang--Mills flow accompanied by a diffeomorphism.
Axially Symmetric Bianchi Type-I Bulk-Viscous Cosmological Models with Time-Dependent and
Indian Academy of Sciences (India)
Nawsad Ali
2013-09-01
The present study deals with spatially homogeneous and anisotropic axially symmetric Bianchi type-I cosmological model with time variable cosmological term in the presence of bulk viscous fluid. The Einstein’s field equations are solved explicitly by time varying deceleration parameter . Consequences of the four cases of phenomenological decay of have been discussed which are consistent with observations. Physical and kinematical parameters of the models are discussed.
The Relativistic Boltzmann Equation on Bianchi Type I Space Time for Hard Potentials
Noutchegueme, Norbert; Takou, Etienne; Tchuengue, E. Kamdem
2017-08-01
In this paper, we consider the Cauchy problem for the spatially homogeneous relativistic Boltzmann equation with small initial data. The collision kernel considered here is for a hard potentials case. The background space-time in which the study is done is the Bianchi type I space-time. Under certain conditions made on the scattering kernel and on the metric, a uniqueness global (in time) solution is obtained in a suitable weighted functional space.
Bianchi Type-I bulk viscous fluid string dust magnetized cosmological model in general relativity
Indian Academy of Sciences (India)
Raj Bali; Anjali
2004-09-01
Bianchi Type-I magnetized bulk viscous fluid string dust cosmological model is investigated. To get a determinate model, we have assumed the conditions and = constant where is the shear, the expansion in the model and the coefficient of bulk viscosity. The behaviour of the model in the presence and absence of magnetic field together with physical and geometrical aspects of the model are also discussed.
Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field cosmology
Energy Technology Data Exchange (ETDEWEB)
Paliathanasis, A. [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Karpathopoulos, L. [University of Athens, Faculty of Physics, Department of Astronomy-Astrophysics-Mechanics, Athens (Greece); Wojnar, A. [Institute for Theoretical Physics, Wroclaw (Poland); Universita' di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Complesso Universitario di Monte S. Angelo, Naples (Italy); Istituto Nazionale di Fisica Nucleare (INFN) Sez. di Napoli, Naples (Italy); Capozziello, S. [Universita' di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Complesso Universitario di Monte S. Angelo, Naples (Italy); Gran Sasso Science Institute (INFN), L' Aquila (Italy); Istituto Nazionale di Fisica Nucleare (INFN) Sez. di Napoli, Naples (Italy)
2016-04-15
Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider general relativity, minimally coupled scalar-field gravity and hybrid gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar-field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries. (orig.)
Bianchi type VI1 cosmological model with wet dark fluid in scale invariant theory of gravitation
Mishra, B
2014-01-01
In this paper, we have investigated Bianchi type VIh, II and III cosmological model with wet dark fluid in scale invariant theory of gravity, where the matter field is in the form of perfect fluid and with a time dependent gauge function (Dirac gauge). A non-singular model for the universe filled with disorder radiation is constructed and some physical behaviors of the model are studied for the feasible VIh (h = 1) space-time.
Bianchi Type Ⅲ Bulk Viscous Barotropic Fluid Cosmological Models with Variable G and A
Institute of Scientific and Technical Information of China (English)
Raj Ba-li; Seema Tinker
2009-01-01
Bianchi type-Ⅲ bulk viscous barotropic fluid cosmological model with variables G and A is investigated. To obtainthe realistic model, we assume the conditions between the metric potentials A, B, C as A/A = B/B = m1/tnand C/C = m2/tn, P = p - 3ηH, η= ηops, p =γp, 0 γ 1, where p is isotropic pressure, η the coefficient of bulk viscosity, ηo and S the constants, H the Hubble constant, m1= 2m2 where m1 0, m2 0. The solutions obtained lead to inflationary phase and the results obtained match with the observations. The case n = 1 for S = 1 is also discussed, relating the results with the observations.PACS: 98. 80. Hω, 04.50. +h, 98.80. CqSpatially homogeneous and anisotropic cosmologi-cal models play a significant role in description of the large scale behaviour of the universe. The choice of anisotropic model in the Einstein system of field equa-tions permits us to obtain cosmological model more general than the Robertson-Walker model. Tikekar and Patel[1] have investigated some exact solutions of massive string for Bianchi type-Ⅲ spacetime in the presence and absence of magnetic field. They have also discussed the behaviour of the model in the ab-sence of magnetic field. Bali and Dave[2] investigated the Bianchi type-Ⅲ string cosmological model with bulk viscosity. Recently Bali and Pradhan[3] investi-gated the Bianchi type-Ⅲ string cosmological models with time-dependent bulk viscosity.
Anisotropic Dark Energy Bianchi Type III Cosmological Models in Brans Dicke Theory of Gravity
Shamir, M Farasat; 10.1139/P2012-007
2012-01-01
The main purpose of this paper is to explore the solutions of Bianchi type $III$ cosmological model in Brans Dicke theory of gravity in the background of anisotropic dark energy. We use the assumption of constant deceleration parameter and power law relation between scalar field $\\phi$ and scale factor $a$ to find the solutions. The physical behavior of the solutions has been discussed using some physical quantities.
Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field cosmology
Paliathanasis, A.; Karpathopoulos, L.; Wojnar, A.; Capozziello, S.
2016-04-01
Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider general relativity, minimally coupled scalar-field gravity and hybrid gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar-field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries.
Photon in Teleparallel Gravity in the Bianchi-type I Space-time
Salti, M; Aydogdu, Oktay; Salti, Mustafa
2005-01-01
In the present paper, using the Fourier analyze method, we study the behavior of the massless spin-1 particles in the teleparallel gravity, and show that the free-space Maxwell equations in the background of the Bianchi-I type space-time give the same results as obtained in teleparallel gravity. Also, using our results, we find the harmonic oscillator behavior of the solutions.
A dossier about the Lunigiana domus of the Bianchi of Moregnano (12th-13th Century
Directory of Open Access Journals (Sweden)
Mario Nobili
2005-12-01
Full Text Available In twelfth and thirteenth century Tuscan sources the term domus means "kinship group defined by common descent", but it can also refer to the overall patrimony belonging to such a group, or alternatively the seigneurial staff, inclusive of servants and tenants. The last of these meanings, the broadest and most comprehensive, is prevalent in twelfth and thirteenth century documents concerning the domus of the Bianchi da Moregnano in Lunigiana, who were vassalls of the Estensi and then the Malaspina.
Structures arising in the asymptotic dynamics of the Bianchi IX model
Piechocki, Wlodzimierz
2016-01-01
We present the analyses of the asymptotic evolution of the general Bianchi IX spacetime using Hamiltonian formulation. The dynamics reveals the existence of special structures, which form knots of variables in the physical phase space. The knots seem to be different from the spikes known in the context of evolution of some spacetime models towards gravitational singularities. Our results may be used as starting point in quantization of the dynamics of knots.
LRS Bianchi Type-V Viscous Fluid Universe With a Time Dependent Cosmological Term $\\Lambda$
Pradhan, Anirudh; Singh, C V
2007-01-01
An LRS Bianchi type-V cosmological models representing a viscous fluid distribution with a time dependent cosmological term $\\Lambda$ is investigated. To get a determinate solution, the viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. It turns out that the cosmological term $\\Lambda(t)$ is a decreasing function of time, which is consistent with recent observations of type Ia supernovae. Various physical and kinematic features of these models have also been explored.
Locally Rotationally Symmetric Bianchi Type-I Model with Time Varying (A) Term
Institute of Scientific and Technical Information of China (English)
R.K.Tiwari; Navin Kumar Jha
2009-01-01
We investigate the locally rotationally symmetric (LRS) Bianchi type-Ⅰ cosmological model for stiff matter and a vacuum solution with a cosmological term proportional to R~(-m) (R is the scale factor and m is a positive constant).The cosmological term decreases with time.We obtain that for both the cases the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term.
Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field cosmology
Paliathanasis, A; Wojnar, A; Capozziello, S
2016-01-01
Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider General Relativity, minimally coupled scalar field gravity and Hybrid Gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries.
Graceful exit from inflation for minimally coupled Bianchi A scalar field models
Beyer, Florian
2013-01-01
We consider the dynamics of Bianchi A scalar field models which undergo inflation. The main question is under which conditions does inflation come to an end and is succeeded by a decelerated epoch. This so-called "graceful exit" from inflation is an important ingredient in the standard model of cosmology, but is, at this stage, only understood for restricted classes of solutions. We present new results obtained by a combination of analytical and numerical techniques.
Interpolating from Bianchi Attractors to Lifshitz and AdS Spacetimes
Kachru, Shamit; Saha, Arpan; Samanta, Rickmoy; Trivedi, Sandip P
2013-01-01
We construct classes of smooth metrics which interpolate from Bianchi attractor geometries of Types II, III, VI and IX in the IR to Lifshitz or $AdS_2 \\times S^3$ geometries in the UV. While we do not obtain these metrics as solutions of Einstein gravity coupled to a simple matter field theory, we show that the matter sector stress-energy required to support these geometries (via the Einstein equations) does satisfy the weak, and therefore also the null, energy condition. Since Lifshitz or $AdS_2 \\times S^3$ geometries can in turn be connected to $AdS_5$ spacetime, our results show that there is no barrier, at least at the level of the energy conditions, for solutions to arise connecting these Bianchi attractor geometries to $AdS_5$ spacetime. The asymptotic $AdS_5$ spacetime has no non-normalizable metric deformation turned on, which suggests that furthermore, the Bianchi attractor geometries can be the IR geometries dual to field theories living in flat space, with the breaking of symmetries being either sp...
Energy and Momentum of the Bianchi-I Type Universes in Tele-parallel Gravity
Salti, M; Salti, Mustafa; Havare, Ali
2005-01-01
In this paper, considering the tele-parallel gravity versions of the Einstein and Landau-Lifshitz energy-momentum prescriptions energy and momentum distribution of the universe based on the Bianchi-I type metrics which includes both the matter and gravitational fields is found to be zero and this results are the same as a previous works of Banerjee-Sen who investigated the same problem in general relativity by using Einstein energy-momentum complex and Xulu who used the general relativity versions of the Landau-lifshitz, Papapetrou and Weinberg energy-momentum complexes for the Bianchi-I type space-times. Another point is that our study agree with the previous works of Cooperstock-Israelit, Rosen, Johri et al. and the previous work of us. The result that total energy of the universe in Bianchi type I universe is supports the viewpoint of Albrow and Tryon and valid not only in the tele-parallel equivalent of general relativity, but also in any tele-parallel model.
Chaos-order transition in Bianchi I non-Abelian Born-Infeld cosmology
Dyadichev, V V; Moniz, P V; Dyadichev, Vladimir V.; Gal'tsov, Dmitri V.; Moniz, Paulo Vargas
2005-01-01
We investigate the Bianchi I cosmology with the homogeneous SU(2) Yang-Mills field governed by the non-Abelian Born-Infeld action. Similar system with the standard Einstein-Yang-Mills (EYM) action is known to exhibit chaotic behavior induced by the Yang-Mills field. When the action is replaced by the Born-Infeld-type non-Abelian action (NBI), the chaos-order transition is observed in the high energy region. This is interpreted as a smothering effect due to (non-perturbative in $alpha'$) string corrections to the classical EYM action. We give a numerical evidence for the chaos-order transition, and present an analytical proof of regularity of color oscillations in the limit of strong Born-Infeld non-linearity. We also perform some general analysis of the Bianchi I NBI cosmology and derive an exact solution in the case when only the U(1) component of the Yang-Mills field is excited. Our new exact solution generalizes the Rosen solution to the Bianchi I Einstein-Maxwell cosmology to the U(1) Einstein-Born-Infeld...
Accelerating dark energy models with anisotropic fluid in Bianchi type-$VI_{0}$ space-time
Pradhan, Anirudh
2012-01-01
Motivated by the increasing evidence for the need of a geometry that resembles Bianchi morphology to explain the observed anisotropy in the WMAP data, we have discussed some features of the Bianchi type-$VI_{0}$ universes in the presence of a fluid that wields an anisotropic equation of state (EoS) parameter in general relativity. We present two accelerating dark energy (DE) models with an anisotropic fluid in Bianchi type-$VI_{0}$ space-time. To prevail the deterministic solution we choose the scale factor $a(t) = \\sqrt{t^{n}e^{t}}$, which yields a time-dependent deceleration parameter (DP), representing a class of models which generate a transition of the universe from the early decelerating phase to the recent accelerating phase. Under the suitable condition, the anisotropic models approach to isotropic scenario. The EoS for dark energy $\\omega$ is found to be time-dependent and its existing range for derived models is in good agreement with the recent observations of SNe Ia data (Knop et al. 2003), SNe Ia...
Future Asymptotic Behaviour of Tilted Bianchi models of type IV and VIIh
Hervik, S; Coley, Alan A; Hervik, Sigbjorn; Hoogen, Robert van den; Coley, Alan
2005-01-01
Using dynamical systems theory and a detailed numerical analysis, the late-time behaviour of tilting perfect fluid Bianchi models of types IV and VII$_h$ are investigated. In particular, vacuum plane-wave spacetimes are studied and the important result that the only future attracting equilibrium points for non-inflationary fluids are the plane-wave solutions in Bianchi type VII$_h$ models is discussed. A tiny region of parameter space (the loophole) in the Bianchi type IV model is shown to contain a closed orbit which is found to act as an attractor (the Mussel attractor). From an extensive numerical analysis it is found that at late times the normalised energy-density tends to zero and the normalised variables 'freeze' into their asymptotic values. A detailed numerical analysis of the type VII$_h$ models then shows that there is an open set of parameter space in which solution curves approach a compact surface that is topologically a torus.
Institute of Scientific and Technical Information of China (English)
HUANG Zeng-Guang; FANG Wei; LU Hui-Qing
2011-01-01
@@ We discuss Bianchi type-Ⅶ0 cosmology with a Dirac field in the Einstein-Cartan(E-C) theory and obtain the equations of the Dirac and gravitational fields in the E-C theory.A Bianchi type-Ⅶ0 inflationary solution is found.When(3/16)S2-σ2＞0, the Universe may avoid singularity.
Terzis, Petros A
2010-01-01
Lie group symmetry analysis for systems of coupled, nonlinear ordinary differential equations is performed in order to obtain the entire solution space to Einstein's field equations for vacuum Bianchi spacetime geometries. The symmetries used are the automorphisms of the Lie algebra of the corresponding three- dimensional isometry group acting on the hyper-surfaces of simultaneity for each Bianchi Type, as well as the scaling and the time reparametrization symmetry. The method is applied to Bianchi Types I; II; IV and V. The result is the acquisition, in each case, of the entire solution space of either Lorenzian of Euclidean signature. This includes all the known solutions for each Type and the general solution of Type IV (in terms of sixth Painlev\\'e transcendent PVI).
Accelerating dark energy models with anisotropic fluid in Bianchi type Ⅵ0 space-time
Institute of Scientific and Technical Information of China (English)
Anirudh Pradhan
2013-01-01
Motivated by the increasing evidence for the need of a geometry that resembles Bianchi morphology to explain the observed anisotropy in the WMAP data,we have discussed some features of Bianchi type Ⅵ0 universes in the presence of a fluid that has an anisotropic equation of state (EoS) parameter in general relativity.We present two accelerating dark energy (DE) models with an anisotropic fluid in Bianchi type Ⅵ0 space-time.To ensure a deterministic solution,we choose the scale factor a(t) =(√tnet),which yields a time-dependent deceleration parameter,representing a class of models which generate a transition of the universe from the early decelerating phase to the recent accelerating phase.Under suitable conditions,the anisotropic models approach an isotropic scenario.The EoS for DE ω is found to be time-dependent and its existing range for derived models is in good agreement with data from recent observations of type Ⅰa supernovae (SNe Ⅰa) (Knop et al.2003),SNe Ⅰa data combined with cosmic microwave background (CMB) anisotropy and galaxy clustering statistics (Tegmark et al.2004a),as well as the latest combination of cosmological datasets coming from CMB anisotropies,luminosity distances of high redshift SNe Ⅰa and galaxy clustering.For different values of n,we can generate a class of physically viable DE models.The cosmological constant Λ is found to be a positive decreasing function of time and it approaches a small positive value at late time (i.e.the present epoch),which is corroborated by results from recent SN Ⅰa observations.We also observe that our solutions are stable.The physical and geometric aspects of both models are also discussed in detail.
Bianchi type-VIh string cloud cosmological models with bulk viscosity
Tripathy, Sunil K.; Behera, Dipanjali
2010-11-01
String cloud cosmological models are studied using spatially homogeneous and anisotropic Bianchi type VIh metric in the frame work of general relativity. The field equations are solved for massive string cloud in presence of bulk viscosity. A general linear equation of state of the cosmic string tension density with the proper energy density of the universe is considered. The physical and kinematical properties of the models have been discussed in detail and the limits of the anisotropic parameter responsible for different phases of the universe are explored.
Study of Bianchi type-I model in f(R,Tψ) gravity
Sharif, M.; Siddiqa, Aisha
2017-03-01
We study the cosmological behavior of locally rotationally symmetric (LRS) Bianchi type-I universe model in f (R ,Tψ) gravity. For this purpose, we evaluate Hubble parameter, effective equation of state parameter (ωeff) and potential of scalar field (ψ) as a function of time using the assumption H = W (ψ). The behavior of these parameters is investigated for different models of W (ψ). It is concluded that exponential form of W (ψ) leads to time independent ωeff which corresponds to different stages of evolution while for the other two models, they correspond to stiff fluid stage.
Bianchi I model in terms of non-standard LQC: Classical dynamics
Dzierzak, Piotr
2009-01-01
The cosmological singularities of the Bianchi I universe are analyzed in the setting of loop geometry underlying the loop quantum cosmology. We solve the Hamiltonian constraint of the theory and find the Lie algebra of elementary observables. Physical compound observables are defined in terms of elementary ones. Modification of classical theory by holonomy around a loop removes the singularities. However, our model has a free parameter that cannot be determined within our method. Testing the model by the data of observational cosmology may be possible after quantization of our modified classical theory.
Ho\\v{r}ava-Lifshitz gravity inspired Bianchi-II cosmology
Giani, Leonardo
2016-01-01
We study different aspects of the Ho\\v{r}ava-Lifshitz inspired Bianchi-II cosmology. First, we present exact solutions for a toy model, where only the cubic in spatial curvature terms are present in the action; then we briefly discuss some exotic singularities, which can appear in this toy model, finally, we analyse qualitatively the equations of motion for a more complicated model, where different powers of the spatial curvature terms are present. Generally, our analysis gives some arguments in favour of existence of an oscillatory approach to the singularity in the universe governed by the Ho\\v{r}ava-Lifshitz type gravity.
LRS Bianchi Type II Massive String Cosmological Models with Magnetic Field in Lyra's Geometry
Directory of Open Access Journals (Sweden)
Raj Bali
2013-01-01
Full Text Available Bianchi type II massive string cosmological models with magnetic field and time dependent gauge function ( in the frame work of Lyra's geometry are investigated. The magnetic field is in -plane. To get the deterministic solution, we have assumed that the shear ( is proportional to the expansion (. This leads to , where and are metric potentials and is a constant. We find that the models start with a big bang at initial singularity and expansion decreases due to lapse of time. The anisotropy is maintained throughout but the model isotropizes when . The physical and geometrical aspects of the model in the presence and absence of magnetic field are also discussed.
Spatially Homogeneous Bianchi Type V Cosmological Model in the Scale-Covariant Theory of Gravitation
Institute of Scientific and Technical Information of China (English)
Shri Ram; M.K.Verma; Mohd.Zeyauddin
2009-01-01
We discuss spatially homogeneous and anisotropic Bianchi type-V spacetime filled with a perfect fluid in the framework of the scaie-covariant theory of gravitation proposed by Canuto et al.By applying the law of variation for Hubble's parameter,exact solutions of the field equations are obtained,which correspond to the model of the universe having a big-bang type singularity at the initial time t=0.The cosmological model,evolving from the initial singularity,expands with power-law expansion and gives essentially an empty space for a large time.The physical and dynamical properties of the model are also discussed.
Bianchi Type V magnetized string dust cosmological models with Petrov-type degenerate
Indian Academy of Sciences (India)
Raj Bali; Umesh K Pareek
2009-05-01
Bianchi Type V massive string cosmological models with free gravitational field of Petrov Type degenerate in the presence of magnetic field with variable magnetic permeability are investigated. The magnetic field is due to an electric current produced along the -axis. The 23 is the only non-vanishing component of electromagnetic field tensor . Maxwell's equations [;] = 0 and $F_{ij}^{ij} = 0$ are satisfied by 23 = constant. The behaviour of the model in the presence and absence of magnetic field and other physical aspects are also discussed.
Quantization of the inhomogeneous Bianchi I model: quasi-Heisenberg picture
Cherkas, S L
2013-01-01
The quantization scheme is suggested for a spatially inhomogeneous 1+1 Bianchi I model. The scheme consists in quantization of the equations of motion and gives the operator (so-called quasi-Heisenberg) equations describing an explicit evolution of a system. Some particular gauge suitable for quantization is proposed. The Wheeler-DeWitt equation is considered in the vicinity of zero scale factor and it is used to construct a space, where the quasi-Heisenberg operators act. Spatial discretization as a UV regularization procedure is suggested for the equations of motion.
LRS Bianchi type-I string cosmological model in f(R, T) gravity
Energy Technology Data Exchange (ETDEWEB)
Sahoo, Pradyumn [Department of Mathematics, Birla Institute of Technology and Science-Pilani, Hyderabad (India)
2016-04-15
In this study the locally rotationally symmetric (LRS) Bianchi type-I (BI) cosmological model has been investigated in the presence of one dimensional cosmic strings in f(R, T) gravity. The exact solutions of the field equations are obtained through the use of constant deceleration parameter [1] and the scalar expansion is proportional to the shear scalar. Considering the accelerating nature of the universe in the present epoch, the physical behavior of the model has been discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Anisotropic Bianchi Type-Ⅰ Model with a Varying A Term
Institute of Scientific and Technical Information of China (English)
R.K.Tiwari; Divya Singh
2012-01-01
Einstein field equations with variable gravitational and cosmological constants are considered in the presence of a perfect fluid for a Bianchi type-I universe by assuming that the cosmological term is proportional to the Hubble parameter..The variation law for vacuum density was recently proposed by Schützhold on the basis of quantum field estimation in a curved expanding background.The cosmological term tends asymptotically to a genuine cosmological constant and the model tends to a de Sitter universe.We obtain that the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term.
Locally-rotationally-symmetric Bianchi type-V cosmology with heat flow
Indian Academy of Sciences (India)
C P Singh; A Beesham
2009-10-01
In this paper we present a spatially homogeneous locally-rotationally-symmetric (LRS) Bianchi type-V cosmological model with perfect fluid and heat flow. A general approach is introduced to solve Einstein’s field equations using a law of variation for the mean Hubble parameter, which is related to average scale factor of the model that yields a constant value for the deceleration parameter. Exact solutions that correspond to singular and non-singular models are found with heat flow. The physical constraints on the solution and, in particular, the thermodynamical laws that govern such solutions are discussed in some detail.
Gravitational Energy-Momentum Density in Bianchi Type-II Space-times
Aydogdu, O
2006-01-01
In this paper, using Einstein and Landau and Lifshitz's energy-momentum complexes in both general relativity and teleparallel gravity, we calculate the total energy distribution(due to matter plus fields) associated with Locally Rotationally Symmetric(LRS) Bianchi type II cosmological models. We show that energy density in these different gravitation theories is the same, so agree with each other. We obtain that the total energy is zero. This result agrees with previous works of Cooperstock and Israelit, Rosen, Johri et al., Banerjee and Sen, Vargas, Aydogdu and Salti. Moreover, our result supports the viewpoints of Albrow and Tryon.
Bianchi Type-Ⅲ Cosmological Models with Gravitational Constant G and the Cosmological Constant Λ
Institute of Scientific and Technical Information of China (English)
J.P.Singh; R.K.Tiwari; Pratibha Shukla
2007-01-01
Einstein field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for the Bianchi type-Ⅲ universe by assuming conservation law for the energy-momentum tensor.Exact solutions of the field equations are obtained by using the scalar of expansion proportional to the shear scalar θχσ,which leads to a relation between metric potential B=Cn,where n is a constant.The corresponding physical interpretation of the cosmological solutions are also discussed.
Bianchi type-II universe with wet dark fluid in general theory of relativity
Mahanta, Chandra Rekha; Sheikh, Azizur Rahman
2017-09-01
In this paper, dark energy models of the universe filled with wet dark fluid are constructed in the frame work of LRS Bianchi type-II space-time in General Theory of Relativity. A new equation of state modeled on the equation of state p = γ ( ρ - ρ_{*} ), which can describe liquid including water, is used. The exact solutions of Einstein's field equations are obtained in quadrature form and the models corresponding to the cases γ = 0 and γ = 1 are discussed in details.
Perfect fluid Bianchi Type-I cosmological models with time varying and
Indian Academy of Sciences (India)
J P Singh; R K Tiwari
2008-04-01
Bianchi Type-I cosmological models containing perfect fluid with time varying and have been presented. The solutions obtained represent an expansion scalar bearing a constant ratio to the anisotropy in the direction of space-like unit vector . Of the two models obtained, one has negative vacuum energy density, which decays numerically. In this model, we obtain ∼ 2, ∼ 44/ and ∼ -2 ( is the cosmic time) which is in accordance with the main dynamical laws for the decay of . The second model reduces to a static solution with repulsive gravity.
Bianchi Type V Matter Filled Universe with Varying Lambda Term in General Relativity
Yadav, Anil Kumar
2009-01-01
Bianchi type V matter filled universe with varying lambda in general relativity are investigated by using the law of variation for the generalized mean Hubble parameter. This yields the constant value of deceleration parameter and generates two types of solutions for the average scale factor one is of power law type and other is of exponential type. The cosmological constant is found to be a decreasing function of time, which is supported by results from recent type Ia supernovae observations. Also it has been found that cosmological constant affects entropy. Some physical and geometric behaviour of the models are discussed.
Institute of Scientific and Technical Information of China (English)
BALI Raj; PAREEK Umesh Kumar; PRADHAN Anirudh
2007-01-01
@@ Bianchi type-Ⅰ massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel is investigated. To obtain the deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution. The magnetic field is due to electric current produced along the x-axis with infinite electrical condúctivity. The behaviour of the model in the presence and absence of magnetic field together with other physical aspects is further discussed.
Ghiti, M. F.; Mebarki, N.; Aissaoui, H.
2015-08-01
The noncommutative Bianchi I curved space-time vierbeins and spin connections are derived. Moreover, the corresponding noncommutative Dirac equation as well as its solutions are presented. As an application within the quantum field theory approach using Bogoliubov transformations, the von Neumann fermion-antifermion pair creation quantum entanglement entropy is studied. It is shown that its behavior is strongly dependent on the value of the noncommutativity θ parameter, k⊥-modes frequencies and the structure of the curved space-time. Various discussions of the obtained features are presented.
The helical phase of chiral nematic liquid crystals as the Bianchi VII(0) group manifold
Gibbons, G W
2011-01-01
We show that the optical structure of the helical phase of a chiral nematic is naturally associated with the Bianchi VII(0) group manifold. The Joets-Ribotta metric governing propagation of the extraordinary rays is invariant under the simply transitive action of the universal cover of the three dimensional Euclidean group of two dimensions. Thus extraordinary light rays are geodesics of a left-invariant metric on this Bianchi type VII(0) group. We are able to solve by separation of variables both the wave equation and the Hamilton-Jacobi equation for this metric. The former reduces to Mathieu's equation and the later to the quadrantal pendulum equation. We further discuss Maxwell's equations for uniaxial optical materials where the configuration is invariant under a group action. The material is not assumed to be impedance matched, thus going beyond the usual scope of transformation optics. We show that for a chiral nematic in its helical phase Maxwell's equations reduce to a generalised Mathieu equation. Ou...
Energy Density Associated with the Bianchi Type-II Space-Time
Aydogdu, O; Aydogdu, Oktay; Salti, Mustafa
2006-01-01
To calculate the total energy distribution (due to both matter and fields including gravitation) associated with locally rotationally symmetric (LRS) Bianchi type-II space-times. We use the Bergmann-Thomson energy-momentum complex in both general relativity and teleparallel gravity. We find that the energy density in these different gravitation theories is vanishing at all times. This result is the same as that obtained by one of the present authors who solved the problem of finding the energy-momentum in LRS Bianchi type-II by using the energy-momentum complexes of Einstein and Landau and Lifshitz. The results of this paper also are consistent with those given in the previous works of Cooperstock and Israelit, Rosen, Johri et al., Banerjee-Sen, Vargas, and Salti et al. In this paper, we perform the calculations for a non-diagonal expanding space-time to determine whether the Bergmann-Thomson energy momentum prescription is consistent with the other formulations. (We previously considered diagonal and expandi...
Energy Associated with Bianchi Type V10 Universe in Teleparallel Gravity
Salti, M
2006-01-01
We obtain the energy and momentum distributions of the universe in the Bianchi type V10 spacetime in Moller's tetrad theory of gravity. The energy-momentum (due to matter and fields including gravity) are found to be zero. The results are exactly the same as obtained by Radinschi for a model of the universe based on the Bianchi type V10 metric using the energy and/or momentum prescriptions of Tolman, Bergmann-Thomson, Moller, Einstein, Landau-Lifshitz in general relativity. The result that the total energy and momentum components of the universe are zero supports the viewpoints of Albrow and Tryon. It is also independent of the teleparallel dimensionless coupling constant, which means that it is valid in any teleparallel model. The results we obtained support the viewpoint of Lessner that the Moller energy-momentum formulation is powerful concept to calculate energy and momentum distributions associated with the universe, and sustains the importance of the energy-momentum definitions in the evaluation of the ...
Li, En-Kun; Geng, Jin-Ling; Duan, Peng-Fei
2016-01-01
Generalized second law of thermodynamics in the Bianchi type I universe with the generalized holographic Ricci dark energy model is studied in this paper. The behavior of dark energy's equation of state parameter indicates that it is matter-like in the early time of the universe but phantom-like in the future. By analysing the evolution of the deviations of state parameter and the total pressure of the universe, we find that for an anisotropic Bianchi type I universe, it transits from a high anisotropy stage to a more homogeneous stage in the near past. Using the normal entropy given by Gibbs' law of thermodynamics, it is proved that the generalized second law of thermodynamics does not always satisfied throughout the history of the universe when we assume the universe is enclosed by the generalized Ricci scalar radius $R_{gr}$. It becomes invalid in the near past to the future, and the formation of the galaxies will be helpful in explaining such phenomenon, for that the galaxies's formation is an entropy inc...
Big-bounce cosmology from quantum gravity: The case of a cyclical Bianchi I universe
Moriconi, Riccardo; Capozziello, Salvatore
2016-01-01
We analyse the classical and quantum dynamics of a Bianchi I model in the presence of a small negative cosmological constant characterizing its evolution in term of the dust-time dualism. We demonstrate that in a canonical metric approach, the cosmological singularity is removed in correspondence to a positive defined value of the dust energy density. Furthermore, the quantum Big-Bounce is connected to the Universe turning point via a well-defined semiclassical limit. Then we can reliably infer that the proposed scenario is compatible with a cyclical Universe picture. We also show how, when the contribution of the dust energy density is sufficiently high, the proposed scenario can be extended to the Bianchi IX cosmology and therefore how it can be regarded as a paradigm for the generic cosmological model. Finally, we investigate the origin of the observed cut-off on the cosmological dynamics, demonstrating how the Big-Bounce evolution can be mimicked by the same semiclassical scenario, where the negative cosm...
Big-bounce cosmology from quantum gravity: The case of a cyclical Bianchi I universe
Moriconi, Riccardo; Montani, Giovanni; Capozziello, Salvatore
2016-07-01
We analyze the classical and quantum dynamics of a Bianchi I model in the presence of a small negative cosmological constant characterizing its evolution in term of the dust-time dualism. We demonstrate that in a canonical metric approach, the cosmological singularity is removed in correspondence to a positive defined value of the dust energy density. Furthermore, the quantum big bounce is connected to the Universe's turning point via a well-defined semiclassical limit. Then we can reliably infer that the proposed scenario is compatible with a cyclical universe picture. We also show how, when the contribution of the dust energy density is sufficiently high, the proposed scenario can be extended to the Bianchi IX cosmology and therefore how it can be regarded as a paradigm for the generic cosmological model. Finally, we investigate the origin of the observed cutoff on the cosmological dynamics, demonstrating how the big-bounce evolution can be mimicked by the same semiclassical scenario, where the negative cosmological constant is replaced via a polymer discretization of the Universe's volume. A direct proportionality law between these two parameters is then established.
Symmetry analysis of the Klein-Gordon equation in Bianchi I spacetimes
Paliathanasis, A.; Tsamparlis, M.; Mustafa, M. T.
2015-02-01
In this work we perform the symmetry classification of the Klein-Gordon equation in Bianchi I spacetime. We apply a geometric method which relates the Lie symmetries of the Klein-Gordon equation with the conformal algebra of the underlying geometry. Furthermore, we prove that the Lie symmetries which follow from the conformal algebra are also Noether symmetries for the Klein-Gordon equation. We use these results in order to determine all the potentials in which the Klein-Gordon admits Lie and Noether symmetries. Due to the large number of cases and for easy reference the results are presented in the form of tables. For some of the potentials we use the Lie admitted symmetries to determine the corresponding invariant solution of the Klein-Gordon equation. Finally, we show that the results also solve the problem of classification of Lie/Noether point symmetries of the wave equation in Bianchi I spacetime and can be used for the determination of invariant solutions of the wave equation.
Symmetry analysis of the Klein-Gordon equation in Bianchi I spacetimes
Paliathanasis, A; Mustafa, M T
2014-01-01
In this work we perform the symmetry classification of the Klein Gordon equation in Bianchi I spacetime. We apply a geometric method which relates the Lie symmetries of the Klein Gordon equation with the conformal algebra of the underlying geometry. Furthermore, we prove that the Lie symmetries which follow from the conformal algebra are also and Noether symmetries for the Klein Gordon equation. We use these resutls in order to determine all the potentials in which the Klein Gordon admits Lie and Noether symmetries. Due to the large number of cases and for easy reference the results are presented in the form of tables. For some of the potentials we use the Lie admitted symmetries to determine the corresponding invariant solution of the Klein Gordon equation. Finally, we show that the results also solve the problem of classification of Lie/Noether point symmetries of the wave equation in Bianchi I spacetime and can be used for the determination of invariant solutions of the wave equation.
A note on proper affine symmetry in Kantowski-Sachs and Bianchi type III space-times
Shabbir, Ghulam
2016-01-01
We investigate proper affine symmetry for the Kantowski-Sachs and Bianchi type III space-times by using holonomy and decomposability, the rank of the 6X6 Riemann matrix and direct integration techniques. It is shown that the very special classes of the above space-times admit proper affine vector fields.
On a proof of the collapse conjecture for a diagonal Bianchi type-IX vacuum space-time
Charters, T
2011-01-01
It is given a simple proof of the collapse conjecture for a diagonal Bianchi type-IX vacuum space-time. It is shown that the codimension of the infinity stable attractor, restricted to the anisotropy plane, is not zero, thus proving that "escape along a channel" is impossible.
Shabbir, Ghulam
2011-01-01
A complete study of Kantowski-Sachs and Bianchi type III space-times according to their proper homothetic vector fields is given by using direct integration technique. Using the above mentioned technique we have shown that very special classes of the above space-times admit proper homothetic vector fields. The dimension of homothetic vector fields is five.
Bianchi Type-Ⅲ String Cosmological Model with Bulk Viscosity in General Relativity
Institute of Scientific and Technical Information of China (English)
WANG Xing-Xiang
2005-01-01
The Bianchi type-Ⅲcosmological model for a cloud string with bulk viscosity are studied. To obtain a determinate solution, it is assumed that the coefficient of bulk viscosity is a power function of the scalar of expansion ζ = kθm and the shear scalar is proportional to scalar of expansion σ∝θ, which leads to the relation between metric potentials B = Cn. The physical features of the model are also discussed. It is found that the power index mhas significant influence on the string model. There is a "big bang" start in the model when m ≤ 1 but there is no the big-bang start when m ＞ 1. In the special case m = 0, the model reduces to the string model of constant coefficient of bulk viscosity that was the result previously given in the literature.
Bianchi Type-Ⅲ String Cosmological Model With Bulk Viscosity and Magnetic Field
Institute of Scientific and Technical Information of China (English)
WANG Xing-Xiang
2006-01-01
@@ The Bianchi type-Ⅲ cosmological model for a cloud string in the presence of bulk viscosity and magnetic field are presented. To obtain the determinate model it is assumed that there is an equation of state ρ = kλ and the scalar of expansion is proportional to the shear scalar θ∝σ, which leads to a relation between metric potentials B = mCn. The physical and geometric aspects of the model are also discussed. The model describes a shearing non-rotating continuously expanding universe with a big-bang start. In the absence of magnetic field, it reduces to the string model with bulk viscosity that was previously given in the literature.
LRS Bianchi type-II string cosmological models in a modified theory of gravitation
Kanakavalli, T.; Ananda Rao, G.; Reddy, D. R. K.
2017-03-01
This paper is devoted to the investigation of spatially homogeneous anisotropic LRS Bianchi type-II cosmological models with string source in a modified theory of gravitation formulated by Harko et al. (Phys. Rev. D 84:024020, 2011) which is universally known as f( R, T) gravity. Here R is the Ricci scalar and T is the trace of the energy momentum tensor. By solving the field equation we have presented massive string and Takabyasi or p-string models in this theory. However it is interesting to note that geometric string in this space-time does not exist in this theory. Physical and geometrical properties of the strings obtained are also discussed.
Bianchi type string cosmological models in f(R,T) gravity
Sahoo, P. K.; Mishra, B.; Sahoo, Parbati; Pacif, S. K. J.
2016-09-01
In this work we have studied Bianchi-III and - VI 0 cosmological models with string fluid source in f( R, T) gravity (T. Harko et al., Phys. Rev. D 84, 024020 (2011)), where R is the Ricci scalar and T the trace of the stress energy-momentum tensor in the context of late time accelerating expansion of the universe as suggested by the present observations. The exact solutions of the field equations are obtained by using a time-varying deceleration parameter. The universe is anisotropic and free from initial singularity. Our model initially shows acceleration for a certain period of time and then decelerates consequently. Several dynamical and physical behaviors of the model are also discussed in detail.
Ribas, M. O.; Samojeden, L. L.; Devecchi, F. P.; Kremer, G. M.
2015-10-01
In this work we investigate a model for the early Universe in a Bianchi type-I metric, where the sources of the gravitational field are a fermionic and a bosonic field, interacting through a Yukawa potential, following the standard model of elementary particles. It is shown that the fermionic field has a negative pressure, while the boson has a small positive pressure. The fermionic field is the responsible for an accelerated regime at early times, but since the total pressure tends to zero for large times, a transition to a decelerated regime occurs. Here the Yukawa potential answers for the duration of the accelerated regime, since by decreasing the value of its coupling constant the transition accelerated-decelerated occurs in later times. The isotropization which occurs for late times is due to the presence of the fermionic field as one of the sources of the gravitational field.
Ribas, M O; Devecchi, F P; Kremer, G M
2015-01-01
In this work we investigate a model for the early Universe in a Bianchi type-I metric, where the sources of the gravitational field are a fermionic and a bosonic field, interacting through a Yukawa potential, following the standard model of elementary particles. It is shown that the fermionic field has a negative pressure, while the boson has a small positive pressure. The fermionic field is the responsible for an accelerated regime at early times, but since the total pressure tends to zero for large times, a transition to a decelerated regime occurs. Here the Yukawa potential answers for the duration of the accelerated regime, since by decreasing the value of its coupling constant the transition accelerated-decelerated occurs in later times. The isotropization which occurs for late times is due to the presence of the fermionic field as one of the sources of the gravitational field.
Bianchi type-V dark energy model with varying EoS parameter
Saha, Bijan
2012-01-01
Within the scope of an anisotropic Bianchi type-V cosmological model we have studied the evolution of the universe. The assumption of a diagonal energy-momentum tensor leads to some severe restriction on the metric functions, which on its part imposes restriction on the components of the energy momentum tensor. This model allows anisotropic matter distribution. Further using the proportionality condition that relates the shear scalar $(\\sigma)$ in the model is proportional to expansion scalar $(\\vartheta)$ and the variation law of Hubble parameter, connecting Hubble parameter with volume scale. Exact solution to the corresponding equations are obtained. The EoS parameter for dark energy as well as deceleration parameter is found to be the time varying functions. A qualitative picture of the evolution of the universe corresponding to different of its stages is given using the latest observational data.
Similarity dark energy models in Bianchi type -I space-time
Ali, Ahmad T; Alzahrani, Abdulah K
2015-01-01
We investigate some new similarity solutions of anisotropic dark energy and perfect fluid in Bianchi type-I space-time. Three different time dependent skewness parameters along the spatial directions are introduced to quantify the deviation of pressure from isotropy. We consider the case when the dark energy is minimally coupled to the perfect fluid as well as direct interaction with it. The Lie symmetry generators that leave the equation invariant are identified and we generate an optimal system of one-dimensional subalgebras. Each element of the optimal system is used to reduce the partial differential equation to an ordinary differential equation which is further analyzed. We solve the Einstein field equations, described by a system of non-linear partial differential equations (NLPDEs), by using the Lie point symmetry analysis method. The geometrical and kinematical features of the models and the behavior of the anisotropy of dark energy, are examined in detail.
Bianchi Type VII_h Models and the WMAP 3-year Data
Jaffe, T R; Eriksen, H K; Górski, K M; Hansen, F K
2006-01-01
Context. A specific example of Bianchi Type VIIh models, i.e. those including universal rotation (vorticity) and differential expansion (shear), has been shown in Jaffe et al. (2005) to correlate unexpectedly with the WMAP first-year data. Aims. We re-assess the signature of this model in the WMAP 3-year data. Methods. The cross-correlation methods are described in Jaffe et al. (2006a). We use the WMAP 3-year data release, including maps for individual years, and perform additional comparisons to assess the influence of both noise and residual foregrounds and eliminate potential non-cosmological sources for the correlation. Results. We confirm that the signal is detected in both the combined 3-year data and the individual yearly sky maps at a level consistent with our original analysis. The significance of the correlation is not affected by either noise or foreground residuals. Conclusions. The results of our previous study are unchanged.
Scalar--flat K\\"ahler metrics with conformal Bianchi V symmetry
Dunajski, Maciej
2010-01-01
We provide an affirmative answer to a question posed by Tod \\cite{Tod:1995b}, and construct all four-dimensional Kahler metrics with vanishing scalar curvature which are invariant under the conformal action of Bianchi V group. The construction is based on the combination of twistor theory and the isomonodromic problem with two double poles. The resulting metrics are non-diagonal in the left-invariant basis and are explicitly given in terms of Bessel functions and their integrals. We also make a connection with the LeBrun ansatz, and characterise the associated solutions of the SU(\\infty) Toda equation by the existence a non-abelian two-dimensional group of point symmetries.
Institute of Scientific and Technical Information of China (English)
Prashant Singh Baghel; Jagdish Prasad Singh
2012-01-01
We consider spatially homogeneous and anisotropic Bianchi type Ⅴ space-time with a bulk viscous fluid source,and time varying gravitational constant G and cosmological term A.The coefficient of bulk viscosity ζ is assumed to be a simple linear function of the Hubble parameter H (i.e.ζ=ζ0 + ζ1H,where ζ0 and ζ1 are constants).The Einstein field equations are solved explicitly by using a law of variation for the Hubble parameter,which yields a constant value of the deceleration parameter.Physical and kinematical parameters of the models are discussed.The models are found to be compatible with the results of astronomical observations.
On the origins of organology: Franz Joseph Gall and a girl named Bianchi.
Eling, Paul; Finger, Stanley; Whitaker, Harry
2017-01-01
Franz Joseph Gall (1758-1828) introduced a new theory of mind and brain at the end of the eighteenth century, which he referred to as organology, dealing with mental functions and their cortical localizations. Gall wrote that observations regarding the verbal learning capacities of his schoolmates brought about his new way of thinking. This widely accepted view, however, requires qualification. Although Gall's experiences and observations as a schoolboy were relevant, especially for his craniology, these childhood memories might have been recalled and reinterpreted after he had started to think about the faculties of mind-specifically after he had met Bianchi, a 5-year-old girl with a special talent for music.
The Momentum 4-Vector Imparted by Gravitational Waves in Bianchi-type Metrics
Havare, A; Salti, M
2006-01-01
Considering the M{\\o}ller, Weinberg and Qadir-Sharif definitions in the general of general relativity, we find the momentum four-vector of the closed universe based on the Bianchi-type metrics. The momentum four-vector which includes both the matter and gravitational field is found to be zero. The result supports the viewpoint of Albrow and Tryon and extends the previous work of Cooperstock and Israelit, Rosen, Johri it et al., Banerjee-Sen, Vargas who investigated the problem of the energy in Friedmann-Robertson-Walker universe and Salt{\\i}-Havare who studied the problem of the energy-momentum of the viscous Kasner-type space-times in tele-parallel gravity.
Dark Energy Models and Laws of Thermodynamics in Bianchi I Model
Sharif, M
2013-01-01
This paper is devoted to check validity of the laws of thermodynamics for LRS Bianchi type I universe model which is filled with combination of dark matter and dark energy. We take two types of dark energy models, i.e., generalized holographic dark energy and generalized Ricci dark energy. It is proved that the first and generalized second law of thermodynamics are valid on the apparent horizon for both the models. Further, we take fixed radius $L$ of the apparent horizon with original holographic or Ricci dark energy. We conclude that the first and generalized second laws of thermodynamics do not hold on the horizon of fixed radius $L$ for both the models.
Bianchi VI{sub 0} and III models: self-similar approach
Energy Technology Data Exchange (ETDEWEB)
Belinchon, Jose Antonio, E-mail: abelcal@ciccp.e [Departamento de Fisica, ETS Arquitectura, UPM, Av. Juan de Herrera 4, Madrid 28040 (Spain)
2009-09-07
We study several cosmological models with Bianchi VI{sub 0} and III symmetries under the self-similar approach. We find new solutions for the 'classical' perfect fluid model as well as for the vacuum model although they are really restrictive for the equation of state. We also study a perfect fluid model with time-varying constants, G and LAMBDA. As in other studied models we find that the behaviour of G and LAMBDA are related. If G behaves as a growing time function then LAMBDA is a positive decreasing time function but if G is decreasing then LAMBDA{sub 0} is negative. We end by studying a massive cosmic string model, putting special emphasis in calculating the numerical values of the equations of state. We show that there is no SS solution for a string model with time-varying constants.
Dynamics of gravitating hadron matter in Bianchi-IX cosmological model
Pavluchenko, Sergey A
2016-01-01
We perform an analysis of the Einstein-Skyrme cosmological model in Bianchi-IX background. We analytically describe asymptotic regimes and semi-analytically -- generic regimes. It appears that depending on the product of Newtonian constant $\\kappa$ with Skyrme coupling $K$, in absence of the cosmological term there are three regimes possible -- recollapse with $\\kK 2$. In presence of the positive cosmological term, power-law regimes turn to exponential (de Sitter) ones while recollapse regime turn to exponential if the value for $\\Lambda$-term is sufficiently large, otherwise the regime remains recollapse. Negative cosmological term leads to the recollapse regardless of $\\kK$. All nonsingular regimes have the squashing coefficient $a(t) \\to 1$ at late times, which is associated with restoring symmetry dynamics. Also all nonsingular regimes appear to be linearly stable -- exponential solutions always while power-law for an open region of initial conditions.
A Dynamical Systems Approach to a Bianchi Type I Viscous Magnetohydrodynamic Model
Kohli, Ikjyot Singh
2013-01-01
We use the expansion-normalized variables approach to study the dynamics of a non-tilted Bianchi Type I cosmological model with both a pure, homogeneous source-free magnetic field and viscous fluid with both bulk and shear viscous effects, employing the ideal magnetohydrodynamic approximation. The dynamical system is then studied in detail through a fixed-point analysis which determines the local sink and source behaviour in combination with standard dynamical system theory and numerical experiments that give a very good indication of the asymptotic behaviour of the system. It is further shown that for certain values of the bulk and shear viscosity and equation of state parameters, the model isotropizes at late times.
Non-vacuum Solutions of Bianchi Type VI_0 Universe in f(R) Gravity
Sharif, M
2010-01-01
In this paper, we solve the field equations in metric f(R) gravity for Bianchi type VI_0 spacetime and discuss evolution of the expanding universe. We find two types of non-vacuum solutions by taking isotropic and anisotropic fluids as the source of matter and dark energy. The physical behavior of these solutions is analyzed and compared in the future evolution with the help of some physical and geometrical parameters. It is concluded that in the presence of isotropic fluid, the model has singularity at $\\tilde{t}=0$ and represents continuously expanding shearing universe currently entering into phantom phase. In anisotropic fluid, the model has no initial singularity and exhibits the uniform accelerating expansion. However, the spacetime does not achieve isotropy as $t\\rightarrow\\infty$ in both of these solutions.
Direction-dependent Jeans instability in an anisotropic Bianchi type I space-time
Dulaney, Timothy R
2008-01-01
We derive the metric for a Bianchi type I space-time with energy density that is dominated by that of a perfect fluid with equation of state $p=w\\rho$ and whose anisotropy is seeded by a fixed norm spacelike vector field. We solve for the evolution of perturbations about this space-time. In particular, the Jeans instability in an expanding flat Friedmann-Robertson-Walker universe is modified by the presence of the vector field so that energy density perturbations develop direction-dependent growth. We also briefly consider observational limits on the vector field vacuum expectation value, $m$. We find that, if $m$ is constant during recombination and thereafter, $m \\lesssim 10^{14} GeV$.
Bianchi Type-II inﬂationary models with constant deceleration parameter in general relativity
Indian Academy of Sciences (India)
C P Singh; S Kumar
2007-05-01
Einstein's ﬁeld equations are considered for a locally rotationally symmetric Bianchi Type-II space–time in the presence of a massless scalar ﬁeld with a scalar potential. Exact solutions of scale factors and other physical parameters are obtained by using a special law of variation for Hubble's parameter that yields a constant value of deceleration parameter. To get inﬂationary solutions, a ﬂat region is considered in which the scalar potential is constant. Power-law and exponential cases are studied and in both solutions there is an anisotropic expansion of the cosmic ﬂuid, but the ﬂuid has vanishing vorticity. A detailed study of geometrical and kinematical properties of solutions has been carried out.
String cosmology in Bianchi type-VI0 dusty Universe with electromagnetic field
Indian Academy of Sciences (India)
Hassan Amirhashchi
2013-04-01
In this paper, the effect of electromagnetic field in the string Bianchi type-VI0 Universe is investigated. Einstein’s field equations have been solved exactly with suitable physical assumptions for two types of strings: (i) massive strings and (ii) Nambu strings. It is found that when the Universe is dominated by massive strings, the existence of electromagnetic field is necessary as it accelerates the expansion of the Universe. But when our Universe is dominated by Nambu strings, the electromagnetic field does not have significant effect on the evolution of the Universe. We have also shown that the early massive string-dominated Universe got converted to Nambu string-dominated Universe later. Our models are derived from an early deceleration phase to an accelerating phase which is consistent with the recent observations of supernovae type-Ia. The physical and geometrical behaviour of these models are also discussed.
Sesma, L Toledo; Loaiza, O
2015-01-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology.
Katore, S. D.; Kapse, D. V.
2017-02-01
In this paper, we have studied the anisotropic and homogeneous Bianchi type-VI 0 Universe filled with dark matter and holographic dark energy components in the framework of general relativity and Lyra's geometry. The Einstein's field equations have been solved exactly by taking the expansion scalar ( 𝜃) in the model is proportional to the shear scalar ( σ). Some physical and kinematical properties of the models are also discussed.
Energy Technology Data Exchange (ETDEWEB)
Narita, Makoto [Department of Mathematics, National Taiwan University, 1, Sec. 4, Roosevelt Rd., Taipei 106, Taiwan (China)
2006-12-21
We discuss the strong cosmic censorship conjecture for cosmological spacetimes in the Einstein-Yang-Mills-dilaton system. Locally rotational symmetric Bianchi I spacetimes are considered. We show local and global existence theorems for the system. Asymptotic behaviour for the spacetimes is also investigated. The curvature invariant is blowup at the initial singularities and the spacetimes are future geodesic complete. Thus, the strong cosmic censorship conjecture for the spacetimes holds.
An interacting two-fluid scenario for dark energy in a Bianchi type-Ⅰ cosmological model
Institute of Scientific and Technical Information of China (English)
Triloki Singh; Raghavendra Chaubey
2012-01-01
We study the evolution of the dark energy parameter within a Bianchi type-Ⅰ cosmological model filled with barotropic fluid and dark energy.The solutions have been obtained for power law and exponential forms of the expansion parameter (they correspond to a constant deceleration parameter in general relativity).After a long time,the models tend to be isotropic under certain conditions.
Indian Academy of Sciences (India)
S D KATORE; D V KAPSE
2017-02-01
In this paper, we have studied the anisotropic and homogeneous Bianchi type-VI$_0$ Universe filled with dark matter and holographic dark energy components in the framework of general relativity and Lyra’s geometry. The Einstein’s field equations have been solved exactly by taking the expansion scalar ($\\theta$) in the model is proportional to the shear scalar ($\\sigma$). Some physical and kinematical properties of the models are also discussed.
Bianchi type-I, -VII{sub 0} and -V cosmological models of Weyssenhoff fluid with magnetic moment
Energy Technology Data Exchange (ETDEWEB)
Lu, H. Q.; Shen, L. M.; Sun, N. J.; Ji, G. F. [Shangai Univ., Shangai (China). Dept. of Physics
2001-07-01
It is derived the system of field equations for a Weyssenhoff fluid including magnetic interaction among the spinning particles prevailing in spatially homogenous, but anisotropic cosmological models of Bianchi types I, VII{sub 0} and V based on the Einstein-Cartan theory. In this work are analyzed the field equations in three different equations of states specified by p=1/3 {rho}, p={rho} and p=0. It has obtained singular and non-singular solutions for Bianchi modes of types I and VII{sub 0} under the state p={rho} but have found that the non-singular solutions are unphysical. During the radiation epoch (p=1/3 {rho}) and the matter epoch (p=0), the analytical solutions found are non-singular for all the stated three Bianchi models, provided that the combined energy arising from matter spin and magnetic interaction among particles overcomes the anisotropy energy in the Universe. It has deduced that the minimum particle numbers for radiation and matter epochs are, respectively, 10{sup 88} and 10{sup 108}, leading to the conclusion that it must be considered the existence of neutrinos and other creation of particles and anti-particles under torsion and strong gravitational field in the early Universe.
Bianchi IX dynamics in bouncing cosmologies: homoclinic chaos and the BKL conjecture
Maier, Rodrigo; Damião Soares, Ivano; Valentino Tonini, Eduardo
2015-12-01
We examine the dynamics of a Bianchi IX model with three scale factors on a 4-dim Lorentzian brane embedded in a 5-dim conformally flat empty bulk with a timelike extra dimension. The matter content is a pressureless perfect fluid restricted to the brane, with the embedding consistently satisfying the Gauss-Codazzi equations. The 4-dim Einstein equations on the brane reduce to a 6-dim Hamiltonian dynamical system with additional terms (due to the bulk-brane interaction) that avoid the singularity and implement nonsingular bounces in the model. We examine the complex Bianchi IX dynamics in its approach to the neighborhood of the bounce which replaces the cosmological singularity of general relativity. The phase space of the model presents (i) two critical points (a saddle-center-center and a center-center-center) in a finite region of phase space, (ii) two asymptotic de Sitter critical points at infinity, one acting as an attractor to late-time acceleration and (iii) a 2-dim invariant plane, which together organize the dynamics of the phase space. The saddle-center-center engenders in the phase space the topology of stable and unstable 4-dim cylinders R × S 3, where R is a saddle direction and S 3 is the center manifold of unstable periodic orbits, the latter being the nonlinear extension of the center-center sector. By a proper canonical transformation the degrees of freedom of the dynamics are separated into one degree connected with the expansion/contraction of the scales of the model, and two rotational degrees of freedom associated with the center manifold S 3. The typical dynamical flow is thus an oscillatory mode about the orbits of the invariant plane. The stable and unstable cylinders are spanned by oscillatory orbits about the separatrix towards the bounce, leading to the homoclinic transversal intersection of the cylinders, as shown numerically in two distinct simulations. The homoclinic intersection manifold has the topology of R × S 2 consisting of
LRS Bianchi type -V cosmology with heat flow in scalar-tensor theory
Energy Technology Data Exchange (ETDEWEB)
Singh, C.P. [Delhi College of Engineering, Delhi (India). Dept. of Applied Mathematics], e-mail: cpsphd@rediffmail.com
2009-12-15
In this paper we present a spatially homogeneous locally rotationally symmetric (LRS) Bianchi type -V perfect fluid model with heat conduction in scalar tensor theory proposed by Saez and Ballester. The field equations are solved with and without heat conduction by using a law of variation for the mean Hubble parameter, which is related to the average scale factor of metric and yields a constant value for the deceleration parameter. The law of variation for the mean Hubble parameter generates two types of cosmologies one is of power -law form and second the exponential form. Using these two forms singular and non -singular solutions are obtained with and without heat conduction. We observe that a constant value of the deceleration parameter is reasonable a description of the different phases of the universe. We arrive to the conclusion that the universe decelerates for positive value of deceleration parameter where as it accelerates for negative one. The physical constraints on the solutions of the field equations, and, in particular, the thermodynamical laws and energy conditions that govern such solutions are discussed in some detail.The behavior of the observationally important parameters like expansion scalar, anisotropy parameter and shear scalar is considered in detail. (author)
The closure constraint for the hyperbolic tetrahedron as a Bianchi identity
Charles, Christoph
2016-01-01
The closure constraint is a central piece of the mathematics of loop quantum gravity. It encodes the gauge invariance of the spin network states of quantum geometry and provides them with a geometrical interpretation: each decorated vertex of a spin network is dual to a quantized polyhedron in $\\mathbb{R}^{3}$. For instance, a 4-valent vertex is interpreted as a tetrahedron determined by the four normal vectors of its faces. We develop a framework where the closure constraint is re-interpreted as a Bianchi identity, with the normals defined as holonomies around the polyhedron faces of a connection (constructed from the spinning geometry interpretation of twisted geometries). This allows us to define closure constraints for hyperbolic tetrahedra (living in the 3-hyperboloid of unit future-oriented spacelike vectors in $\\mathbb{R}^{3,1}$) in terms of normals living all in $SU(2)$ or in $SB(2,\\mathbb{C})$. The latter fits perfectly with the classical phase space developed for $q$-deformed loop quantum gravity su...
A study of positive energy condition in Bianchi V spacetimes via Noether symmetries
Ali, Sajid
2015-01-01
In this paper we use Noether symmetries of the geodesic Lagrangian in Bianchi V spacetimes to study various cosmological solutions of Einstein's field equations. Our first result is the identification of the subalgebras of Noether symmetries of the equations of motions in such spacetimes with dimension 4, 5, 6, 7, 9 or 10 of the maximal algebra of Lie point symmetries of dimension 13. Secondly we give physical interpretation of new cosmological solutions which satisfy positive energy condition and yield critical bounds on the expansion coefficient $\\alpha$, in which the underlying non-flat spacetimes carry interesting physical properties. Specifically the energy density behaves in one of the following ways. (i) It is positive and constant for all time. (ii) It varies with time and attains a global maximum after some time and then asymptotically converges to zero. (iii) It increases for all time and attains a maximum value at the asymptotic limit $t\\rightarrow \\infty$. In particular a non-flat spacetime is obt...
Bianchi I cosmology in the presence of a causally regularized viscous fluid
Venanzi, Marta
2016-01-01
We analyze the dynamics of a Bianchi I cosmology in the presence of a viscous fluid, causally regularized according to the Lichnerowicz approach. We show how the effect induced by shear viscosity is still able to produce a matter creation phenomenon, meaning that also in the regularized theory we observe the Universe emerges from a singularity with a vanishing energy density value. We discuss the structure of the singularity in the isotropic limit, when bulk viscosity is the only retained contribution. We see that, in the regularized theory we address, as far as viscosity is not a dominant effect, the dynamics of the isotropic Universe possesses the usual inviscid power-law behavior, but in correspondence of an effective equation of state, depending on the bulk viscosity coefficient. Finally, we show that in the limit of a strong non-thermodynamical equilibrium of the Universe, mimiced by a dominant contribution of the effective viscous pressure, a power-law inflation behavior of the Universe appears and the ...
Locally-rotationally-symmetric Bianchi type-V cosmology in general relativity
Indian Academy of Sciences (India)
C P Singh
2009-02-01
A spatially homogeneous locally-rotationally-symmetric (LRS) Bianchi type-V cosmological model is considered with a perfect fluid in general relativity. We present two types of cosmologies (power-law and exponential forms) by using a law of variation for the mean Hubble parameter that yields a constant value for the deceleration parameter. We discuss the physical properties of the non-flat and flat models in each cosmology. Exact solutions that correspond to singular and non-singular models are presented. In a generic situation, models can be interpolated between different phases of the Universe. We find that a constant value for the deceleration parameter is reasonable for a description of different phases of the Universe. We arrive at the conclusion that the Universe decelerates when the value of the deceleration parameter is positive whereas it accelerates when the value is negative. The dynamical behaviours of the solutions and kinematical parameters like expansion, shear and the anisotropy parameter are discussed in detail in each section. Exact expressions for look-back time, luminosity distance and event horizon vs. redshift are derived and their significances are discussed in some detail. It has been observed that the solutions are compatible with the results of recent observations.
Indian Academy of Sciences (India)
Sezgin Aygün; İsmail Tarhan
2012-04-01
In this study we have investigated the energy–momentum distributions for homogeneous and anisotropic Bianchi type-IV in B class Universe. For this purpose, we have used energy–momentum complexes of Einstein, Bergmann–Thomson, Landau–Lifshitz (LL), Papapetrou, Tolman and Møller in general relativity (GR) as also Einstein, Bergmann–Thomson, Landau–Lifshitz and Møller in teleparallel gravity (TG). From the obtained results we have found that Einstein and Bergmann–Thomson distributions are exactly giving the same results in GR and TG but the Landau–Lifshitz, Papapetrou Tolman and Møller energy–momentum distributions do not provide the same results with Einstein and Bergmann–Thomson in GR and TG. Furthermore, Einstein, Bergmann–Thomson and LL results are the same in different gravitation theories and we get that both GR and TG are equivalent theories for these prescriptions. From the obtained solutions, we could say that these are equivalent theories. Also, Møller energy–momentum distributions do not give the same results in GR and TG. However, we have found that all energy prescriptions are negative and our results agree with Nester et al.
Cosmological constant in the Bianchi type-I-modiﬁed Brans–Dicke cosmology
Indian Academy of Sciences (India)
A K Azad; J N Islam
2003-01-01
In 1961, Brans and Dicke [1] provided an interesting alternative to general relativity based on Mach’s principle. To understand the reasons leading to their ﬁeld equations, we ﬁrst consider homogeneous and isotropic cosmological models in the Brans–Dicke theory. Accordingly we start with the Robertson–Walker line element and the energy tensor of a perfect ﬂuid. The scalar ﬁeld is now a function of the cosmic time only. Then we consider spatially homogeneous and anisotropic Bianchi type-I-cosmological solutions of modiﬁed Brans–Dicke theory containing barotropic ﬂuid. These have been obtained by imposing a condition on the cosmological parameter (). Again we try to focus the meaning of this cosmological term and to relate it to the time coordinate which gives us a collapse singularity or the initial singularity. On the other hand, our solution is a generalization of the solution found by Singh and Singh [2]. As far as we are aware, such solution has not been given earlier.
Exploring Vacuum Energy in a Two-Fluid Bianchi Type I Universe
Kohli, Ikjyot Singh
2014-01-01
We use a dynamical systems approach based on the method of orthonormal frames to study the dynamics of a two-fluid, non-tilted Bianchi Type I cosmological model. In our model, one of the fluids is a fluid with bulk viscosity, while the other fluid assumes the role of a cosmological constant and represents nonnegative vacuum energy. We begin by completing a detailed fixed-point analysis of the system which gives information about the local sinks, sources and saddles. We then proceed to analyze the global features of the dynamical system by using topological methods such as finding Lyapunov and Chetaev functions, and finding the $\\alpha$- and $\\omega$-limit sets using the LaSalle invariance principle. The fixed points found were a flat Friedmann-LeMa\\^{\\i}tre-Robertson-Walker (FLRW) universe with no vacuum energy, a de Sitter universe, a flat FLRW universe with both vacuum and non-vacuum energy, and a Kasner quarter-circle universe. We also show in this paper that the vacuum energy we observe in our present-day...
The Riemann tensor and the Bianchi identity in 5D space-time
Taki, Mehran; Mirjalili, Abolfazl
2017-01-01
The initial assumption of theories with extra dimension is based on the efforts to yield a geometrical interpretation of the gravitation field. In this paper, using an infinitesimal parallel transportation of a vector, we generalize the obtained results in four dimensions to five-dimensional space-time. For this purpose, we first consider the effect of the geometrical structure of 4D space-time on a vector in a round trip of a closed path, which is basically quoted from chapter three of Ref. [5]. If the vector field is a gravitational field, then the required round trip will lead us to an equation which is dynamically governed by the Riemann tensor. We extend this idea to five-dimensional space-time and derive an improved version of Bianchi's identity. By doing tensor contraction on this identity, we obtain field equations in 5D space-time that are compatible with Einstein's field equations in 4D space-time. As an interesting result, we find that when one generalizes the results to 5D space-time, the new field equations imply a constraint on Ricci scalar equations, which might be containing a new physical insight.
Cosmological Bianchi Class A models in S\\'aez-Ballester theory
Socorro, J; Espinoza-García, Abraham; Pimentel, Luis O; Romero, Priscila
2011-01-01
We use the S\\'aez-Ballester (SB) theory on anisotropic Bianchi Class A cosmological model, with barotropic fluid and cosmological constant, using the Hamilton or Hamilton-Jacobi approach. Contrary to claims in the specialized literature, it is shown that the S\\'aez-Ballester theory cannot provide a realistic solution to the dark matter problem of Cosmology for the dust epoch, without a fine tunning because the contribution of the scalar field in this theory is equivalent to a stiff fluid (as can be seen from the energy--momentum tensor for the scalar field), that evolves in a different way as the dust component. To have similar contributions of the scalar component and the dust component implies that their past values were fine tunned. So, we reinterpreting this null result as an indication that dark matter plays a central role in the formation of structures and galaxy evolution, having measureable effects in the cosmic microwave bound radiation, and than this formalism yield to this epoch as primigenius resu...
Late-time behaviour of the tilted Bianchi type VIh models
Hervik, S; Lim, W C; Coley, A A
2007-01-01
We study tilted perfect fluid cosmological models with a constant equation of state parameter in spatially homogeneous models of Bianchi type VI$_h$ using dynamical systems methods and numerical experimentation, with an emphasis on their future asymptotic evolution. We determine all of the equilibrium points of the type VI$_h$ state space (which correspond to exact self-similar solutions of the Einstein equations, some of which are new), and their stability is investigated. We find that there are vacuum plane-wave solutions that act as future attractors. In the parameter space, a `loophole' is shown to exist in which there are no stable equilibrium points. We then show that a Hopf-bifurcation can occur resulting in a stable closed orbit (which we refer to as the Mussel attractor) corresponding to points both inside the loophole and points just outside the loophole; in the former case the closed curves act as late-time attractors while in the latter case these attracting curves will co-exist with attracting eq...
Cosmological dynamics of magnetic Bianchi I in viable f(R) models of gravity
Liu, Xuyang; Channuie, Phongpichit; Samart, Daris
2017-09-01
Standard dynamical system analysis of Einstein-Maxwell equation in f(R) theories is considered in this work. We investigate cosmological dynamics of a uniform magnetic field in the Orthogonal Spatially Homogeneous (OSH) Bianchi I universe with viable f(R) models of gravity. In this work, the f(R) = R - αRn and f(R) =(Rb - Λ) c models are examined by using our dynamical system analysis. Our results show that both of two f(R) models have a viable cosmological consequence identical to the analysis present in Amendola and Tsujikawa (2008) for the FLRW background. Contrary to Amendola and Tsujikawa (2008), we discover in our models that there is an additional anisotropic and non-zero cosmological magnetic fields fixed point emerging before the present of the standard matter epoch. This means that the universe has initially isotropic stage with the intermediated epoch as the anisotropic background and it ends up with the isotropic late-time acceleration. The primordial magnetic fields play a crucial role of the shear evolutions obtained from these two models which have the same scaling of the cosmic time as σ ∼t-1/3, instead of σ ∼t-1 for the absence of the primordial magnetic cases.
Dynamics of a Vacuum Bianchi Type V Universe with an Arbitrary Cosmological Constant
Kohli, Ikjyot Singh
2016-01-01
In this paper, we describe the dynamics of a Bianchi Type V vacuum universe with an arbitrary cosmological constant. We begin by using an orthonormal frame approach to write Einstein's field equations as a coupled system of first-order ordinary differential equations. The equilibrium points of the resulting dynamical system were found to be expanding and contracting de Sitter universe solutions, a Minkowski spacetime solution, and static Anti-de Sitter universe solutions, which were characterized by a negative cosmological constant in addition to constant negative spatial curvature. While the expanding de Sitter universe solution was found to be globally stable for $\\Lambda > 0$, we also show that the AdS solution is globally stable for $\\Lambda < 0$. The work in this paper shows that it as at least plausible that the cosmological constant that we observe to be positive today may have had different, but, perhaps \\emph{discrete} values at different epochs in the history of the universe's evolution. That is,...
A study of positive energy condition in Bianchi V spacetimes via Noether symmetries
Energy Technology Data Exchange (ETDEWEB)
Ali, Sajid; Hussain, Ibrar [National University of Sciences and Technology, Department of Basic Sciences, School of Electrical Engineering and Computer Science, Islamabad (Pakistan)
2016-02-15
In this paper we use Noether symmetries of the geodesic Lagrangian in Bianchi V spacetimes to study various cosmological solutions of Einstein's field equations. Our first result is the identification of the subalgebras of Noether symmetries of the equations of motion in such spacetimes with dimension 4, 5, 6, 7, 9 or 10 of the maximal algebra of Lie point symmetries of dimension 13. Second, we give a physical interpretation of new cosmological solutions which satisfy the positive energy condition and yield critical bounds on the expansion coefficient α, in which the underlying nonflat spacetimes have interesting physical properties. Specifically the energy density behaves in one of the following ways. (i) It is positive and constant for all time. (ii) It varies with time and attains a global maximum after some time and then asymptotically converges to zero. (iii) It increases for all time and attains a maximum value at the asymptotic limit t → ∞ In particular a non-flat spacetime is obtained that mimics the expansion in a flat FRW universe dominated by vacuum energy such that the expansion factor has the same form in both. However, the energy density is dynamical in the former. (orig.)
Energy Momentum Localization for Bianchi I-III-V-VI0 Universe in Teleparallel Gravity
Aygun, S; Tarhan, I; Aygun, Melis; Aygun, Sezgin; Tarhan, Ismail
2006-01-01
In this paper, considering the tele-parallel gravity versions of the Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum prescriptions energy and momentum distribution of the universe based on the general Bianchi type I-III-V-VI0 universe and its transforms type I, III, V, VI0 metrics, respectively which includes both the matter and gravitational fields are found. We obtain that Einstein and Bergmann-Thomson definitions of the energy-momentum complexes give the same results, while Landau-Lifshitz's energy-momentum definition does not provide same results for these type of metrics. This results are the same as a previous works of Aygun et al., the Authors investigate the same problem in general relativity by using the Einstein, Moller, Bergmann-Thomson, Landau-Lifshitz (LL) and Papapetrou's definitions. Furthermore, we show that for the Bianci type-I and type-VIo all the formulations give the same result. These results supports the viewpoints of Banerjee-Sen, Xulu and Aydogdu-Salti. Another point is...
Pradhan, Anirudh; Rikhvitsky, Victor
2013-01-01
The present study deals with the exact solutions of the Einstein's field equations with variable gravitational and cosmological "constants" for a spatially homogeneous and anisotropic Bianchi type-I space-time. To study the transit behaviour of Universe, we consider a law of variation of scale factor $a(t) = \\left(t^{k} e^{t}\\right)^{\\frac{1}{n}}$ which yields a time dependent deceleration parameter (DP) $q = - 1 + \\frac{nk}{(k + t)^{2}}$, comprising a class of models that depicts a transition of the universe from the early decelerated phase to the recent accelerating phase. We find that the time dependent DP is reasonable for the present day Universe and give an appropriate description of the evolution of the universe. For $n = 0.27k$, we obtain $q_{0} = -0.73$ which is similar to observed value of DP at present epoch. It is also observed that for $n \\geq 2$ and $k = 1$, we obtain a class of transit models of the universe from early decelerating to present accelerating phase. For $k = 0$, the universe has no...
Uniqueness of the Fock quantization of scalar fields in a Bianchi I cosmology with unitary dynamics
Cortez, Jerónimo; Navascués, Beatriz Elizaga; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.
2016-11-01
The Fock quantization of free scalar fields is subject to an infinite ambiguity when it comes to choosing a set of annihilation and creation operators, a choice that is equivalent to the determination of a vacuum state. In highly symmetric situations, this ambiguity can be removed by asking vacuum invariance under the symmetries of the system. Similarly, in stationary backgrounds, one can demand time-translation invariance plus positivity of the energy. However, in more general situations, additional criteria are needed. For the case of free (test) fields minimally coupled to a homogeneous and isotropic cosmology, it has been proven that the ambiguity is resolved by introducing the criterion of unitary implementability of the quantum dynamics, as an endomorphism in Fock space. This condition determines a specific separation of the time dependence of the field, so that this splits into a very precise background dependence and a genuine quantum evolution. Furthermore, together with the condition of vacuum invariance under the spatial Killing symmetries, unitarity of the dynamics selects a unique Fock representation for the canonical commutation relations, up to unitary equivalence. In this work, we generalize these results to anisotropic spacetimes with shear, which are therefore not conformally symmetric, by considering the case of a free scalar field in a Bianchi I cosmology.
The closure constraint for the hyperbolic tetrahedron as a Bianchi identity
Charles, Christoph; Livine, Etera R.
2017-07-01
The closure constraint is a central piece of the mathematics of loop quantum gravity. It encodes the gauge invariance of the spin network states of quantum geometry and provides them with a geometrical interpretation: each decorated vertex of a spin network is dual to a quantized polyhedron in R3. For instance, a 4-valent vertex is interpreted as a tetrahedron determined by the four normal vectors of its faces. We develop a framework where the closure constraint is re-interpreted as a Bianchi identity, with the normals defined as holonomies around the polyhedron faces of a connection (constructed from the spinning geometry interpretation of twisted geometries). This allows us to define closure constraints for hyperbolic tetrahedra (living in the 3-hyperboloid of unit future-oriented spacelike vectors in R^{3,1}) in terms of normals living all in SU(2) or in SB(2,C). The latter fits perfectly with the classical phase space developed for q-deformed loop quantum gravity supposed to account for a non-vanishing cosmological constant Λ >0. This allows the interpretation of q-deformed twisted geometries as actual discrete hyperbolic triangulations for 4d quantum gravity.
Hamiltonian formulation and exact solutions of the Bianchi type I space-time in conformal gravity
Demaret, J; Scheen, C
1999-01-01
We develop a Hamiltonian formulation of the Bianchi type I space-time in conformal gravity, i.e. the theory described by a Lagrangian that is defined by the contracted quadratic product of the Weyl tensor, in a four-dimensional space-time. We derive the explicit forms of the super-Hamiltonian and of the constraint expressing the conformal invariance of the theory and we write down the system of canonical equations. To seek out exact solutions of this system we add extra constraints on the canonical variables and we go through a global involution algorithm which eventually leads to the closure of the constraint algebra. The Painleve approach provides us with a proof of non-integrability, as a consequence of the presence of movable logarithms in the general solution of the problem. We extract all possible particular solutions that may be written in closed analytical form. This enables us to demonstrate that the global involution algorithm has brought forth the complete list of exact solutions that may be writte...
Generalized Bianchi's Model of IEEE 802.11 Distributed Coordination Function
Yin, Dongjie; Lee, Tony T
2011-01-01
A widely adopted two-dimensional Markov chain model of the IEEE 802.11 DCF was introduced by Bianchi to characterize the backoff behavior of a single node under a saturated traffic condition. Using this approach, we propose a queuing model for the 802.11 DCF under a non-saturated traffic environment. The input buffer of each node is modeled as a Geo/G/1 queue, and the packet service time distribution is derived from a one-dimensional Markov chain of 802.11 DCF with the underlying scheduling algorithm. The DCF defines two access mechanisms, namely the Basic access mechanism and the request-to-send/clear-to-send (RTS/CTS) access mechanism. Based on our model, performance analyses of both schemes are studied with exponential backoff scheduling. Specifically, we obtain the characteristic equation of network throughput, the stable throughput region, and the bounded delay region. For both access schemes, the bounded delay region is a subset of the stable throughput region. Our results show that the RTS/CTS access m...
The Bianchi devotion of 1399: a political analysis of a peace movement
Directory of Open Access Journals (Sweden)
Stefania Giraudo
2013-06-01
Full Text Available Nel 1399 l’Italia fu percorsa da un a serie di processioni, note come la devozione dei Bianchi. La storiografia ha considerato questo fenomeno – che è parte di una lunga tradizione di movimenti devozionali e penitenziali che si manifestarono in Italia e in Europa tra il secolo XIII e XIV – come un movimento omogeneo e compatto, un evento simbolico, l’ultima manifestazione pubblica del tardo medioevo. Questo articolo intende fornire nuovi indizi grazie a un’indagine che si prefigge di riconoscere le interferenze tra i riti religiosi e le pratiche politiche, ponendo l’attenzione innanzitutto ed essenzialmente sull’elemento processionale della devozione come un evento pubblico inserito nel contesto urbano. In particolare, tramite l’analisi delle differenti reazioni dei gruppi di potere nelle città coinvolte nelel processioni, questo studio intende individuare un quadro più articolato degli effetti reali delle processioni pubbliche. I ben documentati casi di Lucca, Pistoia e Padova mostrano un rito multiforme, in cui tanti impulsi diversi erano ricomposti nella prospettiva comune della pace. Questo movimento diede luogo a un nuovo ed eterogeneo spazio di potere, che provocò tensioni politiche che riflettevano e talora alteravano l’equilibrio locale del potere.
Maier, Rodrigo; Tonini, Eduardo Valentino
2015-01-01
We examine the dynamics of a Bianchi IX model on a 4-dim brane embedded in a 5-dim conformally flat empty bulk with a timelike extra dimension. Einstein's equations on the brane reduces to a 6-dim Hamiltonian dynamical system with additional terms that implement nonsingular bounces in the model. The phase space of the model has two critical points (a saddle-center-center and a center-center-center) in a finite region of phase space, and two asymptotic de Sitter critical points, one acting as an attractor to late-time dynamics. The saddle-center-center engenders in the phase space the topology of stable and unstable 4-dim cylinders $R \\times S^3$, where $R$ is a saddle direction and $S^3$ is the center manifold of unstable periodic orbits (the nonlinear extension of the center-center sector). By a proper canonical transformation we separate the degrees of freedom of the dynamics into one degree connected with the expansion/contraction of the scales of the model, and two rotational degrees of freedom connected ...
Hossienkhani, Hossien
2016-01-01
A spatially homogeneous and anisotropic Bianchi type I universe has been studied with the ghost dark energy (GDE) in the framework of Brans-Dicke theory. For this purpose, we use the squared sound speed $v_s^2$ whose sign determines the stability of the model. At first, we obtain the equation of state parameter, $\\omega_\\Lambda$, the deceleration parameter $q$ and the evolution equation of the ghost dark energy. Then, we extend our study to the case of ghost dark energy in a non-isotropic and Brans-Dicke framework and find out that the transition of $\\omega_\\Lambda$ to the phantom regime can be more easily accounted for than when it is restored into the Einstein field equations. Our numerical result show the effects of the interaction and anisotropic on the evolutionary behaviour the ghost dark energy models. In conclusion, we find evidence that the ghost dark energy in BD theory can lead to a stable universe favored by observations at the present time.
Five Dimensional Bianchi Type-V Space-Time in f (R,T Theory of Gravityw
Directory of Open Access Journals (Sweden)
L.S. Ladke,
2016-02-01
Full Text Available We study the spatially homogeneous anisotropic Bianchi type-V universe in f(R,T theory of gravity, where R is the Ricci scalar and T is the trace of the energy-momentum tensor. We assume the variation law of mean Hubble parameter and constant deceleration parameter to find two different five dimensional exact solutions of the modified field equations. The first solution yields a singular model for n 0 while the second gives a nonsingular model for n 0. The physical quantities are discussed for both models in future evolution of the universe.
Indian Academy of Sciences (India)
S D Katore; R S Rane; K S Wankhade
2011-04-01
Bianchi type-I massive string cosmological model for perfect ﬂuid distribution in the presence of magnetic ﬁeld is investigated in Rosen’s [Gen. Relativ. Gravit. 4, 435 (1973)] bimetric theory of gravitation. To obtain the deterministic model in terms of cosmic time, we have used the condition $A = (B C)^n$, where n is a constant, between the metric potentials. The magnetic ﬁeld is due to the electric current produced along the -axis with inﬁnite electrical conductivity. Some physical and geometrical properties of the exhibited model are discussed and studied.
Indian Academy of Sciences (India)
R CHAUBEY; A K SHUKLA; RAKESH RAUSHAN
2017-04-01
The general class of Bianchi cosmological models with dark energy in the form of modified Chaplygin gas with variable $\\Lambda$ and $G$ and bulk viscosity have been considered. We discuss three types of average scalefactor by using a special law for deceleration parameter which is linear in time with negative slope. The exact solutions to the corresponding field equations are obtained. We obtain the solution of bulk viscosity ($\\xi$ ), cosmologicalconstant ($\\Lambda$), gravitational parameter ($G$) and deceleration parameter ($q$) for different equations of state. The model describes an accelerating Universe for large value of time $t$ , wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.
Bianchi type-V cosmological models with perfect fluid and heat flow in Saez–Ballester theory
Indian Academy of Sciences (India)
Shri Ram; M Zeyauddin; C P Singh
2009-02-01
In this paper we discuss the variation law for Hubble's parameter with average scale factor in a spatially homogeneous and anisotropic Bianchi type-V space-time model, which yields constant value of the deceleration parameter. We derive two laws of variation of the average scale factor with cosmic time, one is of power-law type and the other is of exponential form. Exact solutions of Einstein field equations with perfect fluid and heat conduction are obtained for Bianchi type-V space-time in these two types of cosmologies. In the cosmology with the power-law, the solutions correspond to a cosmological model which starts expanding from the singular state with positive deceleration parameter. In the case of exponential cosmology, we present an accelerating non-singular model of the Universe. We find that the constant value of deceleration parameter is reasonable for the present day Universe and gives an appropriate description of evolution of Universe. We have also discussed different types of physical and kinematical behaviour of the models in these two types of cosmologies.
Barrow, John D
2015-01-01
We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether cyclic universe scenarios, like the ekpyrotic model, do indeed lead to isotropisation on approach to a singularity (or bounce) in the presence of dominant ultra-stiff pressure anisotropies. We specialise to consider the closed Bianchi type IX universe and show that when the anisotropic pressures are stiffer on average than any isotropic ultra-stiff fluid then, if they dominate on approach to the singularity, it will be anisotropic. We include an isotropic ultra-stiff ghost fluid with negative energy density in order to create a cosmological bounce at finite volume in the absence of the anisotropic fluid. When the dominant anisotropic fluid is present it leads to an anisotropic cosmological singularity rather than an isotropic bounce. The inclusion of anisotropic stresses generated by collisionl...
Institute of Scientific and Technical Information of China (English)
Anirudh Pradhan
2011-01-01
The present study deals with a spatially homogeneous and anisotropic Bianchi-I cosmological models representing massive strings with magnetic field and decaying vacuum energy density A. The energy-momentum tensor,as formulated by Letelier (1983), has been used to construct massive string cosmological models for which we assume the expansion scalar in the models is proportional to one of the components of shear tensor. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's parameter in Bianchi-I space-time. The variation law for Hubble's parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. We have made a comparative study of accelerating and decelerating models in the presence of string scenario. The study reveals that massive strings dominate in the decelerating universe whereas strings dominate in the accelerating universe. The strings eventually disappear from the universe for sufficiently large times, which is in agreement with current astronomical observations. The cosmological constant A is found to be a positive decreasing function of time which is corroborated by results from recent supernovae Ia observations. The physical and geometric properties of the models have been also discussed in detail.
Akbar, M M
2004-01-01
We find instanton/cosmological solutions with biaxial Bianchi-IX symmetry, involving non-trivial spatial dependence of the $\\bbbc P^{1}$- and $\\bbbc P^{2}$-sigma-models coupled to gravity. Such manifolds arise in N=1, $d=4$ supergravity with supermatter actions and hence the solutions can be embedded in supergravity. There is a natural way in which the standard coordinates of these manifolds can be mapped into the four-dimensional physical space. Due to its special symmetry, we start with $\\bbbc P^{2}$ with its corresponding scalar Ansatz; this further requires the spacetime to be $SU(2) \\times U(1)$-invariant. The problem then reduces to a set of ordinary differential equations whose analytical properties and solutions are discussed. Among the solutions there is a surprising, special-family of exact solutions which owe their existence to the non-trivial topology of $\\bbbc P^{2}$ and are in 1-1 correspondence with matter-free Bianchi-IX metrics. These solutions can also be found by coupling $\\bbbc P^{1}$ to g...
Rimondi, Valentina; Gray, John E; Costagliola, Pilario; Vaselli, Orlando; Lattanzi, Pierfranco
2012-01-01
The distribution and translocation of mercury (Hg) was studied in the Paglia River ecosystem, located downstream from the inactive Abbadia San Salvatore mine (ASSM). The ASSM is part of the Monte Amiata Hg district, Southern Tuscany, Italy, which was one of the world's largest Hg districts. Concentrations of Hg and methyl-Hg were determined in mine-waste calcine (retorted ore), sediment, water, soil, and freshwater fish collected from the ASSM and the downstream Paglia River. Concentrations of Hg in calcine samples ranged from 25 to 1500 μg/g, all of which exceeded the industrial soil contamination level for Hg of 5 μg/g used in Italy. Stream and lake sediment samples collected downstream from the ASSM ranged in Hg concentration from 0.26 to 15 μg/g, of which more than 50% exceeded the probable effect concentration for Hg of 1.06 μg/g, the concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Stream and lake sediment methyl-Hg concentrations showed a significant correlation with TOC indicating considerable methylation and potential bioavailability of Hg. Stream water contained Hg as high as 1400 ng/L, but only one water sample exceeded the 1000 ng/L drinking water Hg standard used in Italy. Concentrations of Hg were elevated in freshwater fish muscle samples and ranged from 0.16 to 1.2 μg/g (wet weight), averaged 0.84 μg/g, and 96% of these exceeded the 0.3 μg/g (methyl-Hg, wet weight) USEPA fish muscle standard recommended to protect human health. Analysis of fish muscle for methyl-Hg confirmed that >90% of the Hg in these fish is methyl-Hg. Such highly elevated Hg concentrations in fish indicated active methylation, significant bioavailability, and uptake of Hg by fish in the Paglia River ecosystem. Methyl-Hg is highly toxic and the high Hg concentrations in these fish represent a potential pathway of Hg to the human food chain.
Rimondi, V.; Gray, J.E.; Costagliola, P.; Vaselli, O.; Lattanzi, P.
2012-01-01
The distribution and translocation of mercury (Hg) was studied in the Paglia River ecosystem, located downstream from the inactive Abbadia San Salvatore mine (ASSM). The ASSM is part of the Monte Amiata Hg district, Southern Tuscany, Italy, which was one of the world’s largest Hg districts. Concentrations of Hg and methyl-Hg were determined in mine-waste calcine (retorted ore), sediment, water, soil, and freshwater fish collected from the ASSM and the downstream Paglia River. Concentrations of Hg in calcine samples ranged from 25 to 1500 μg/g, all of which exceeded the industrial soil contamination level for Hg of 5 μg/g used in Italy. Stream and lake sediment samples collected downstream from the ASSM ranged in Hg concentration from 0.26 to 15 μg/g, of which more than 50% exceeded the probable effect concentration for Hg of 1.06 μg/g, the concentration above which harmful effects are likely to be observed in sediment-dwelling organisms. Stream and lake sediment methyl-Hg concentrations showed a significant correlation with TOC indicating considerable methylation and potential bioavailability of Hg. Stream water contained Hg as high as 1400 ng/L, but only one water sample exceeded the 1000 ng/L drinking water Hg standard used in Italy. Concentrations of Hg were elevated in freshwater fish muscle samples and ranged from 0.16 to 1.2 μg/g (wet weight), averaged 0.84 μg/g, and 96% of these exceeded the 0.3 μg/g (methyl-Hg, wet weight) USEPA fish muscle standard recommended to protect human health. Analysis of fish muscle for methyl-Hg confirmed that > 90% of the Hg in these fish is methyl-Hg. Such highly elevated Hg concentrations in fish indicated active methylation, significant bioavailability, and uptake of Hg by fish in the Paglia River ecosystem. Methyl-Hg is highly toxic and the high Hg concentrations in these fish represent a potential pathway of Hg to the human food chain.
Nigro, Salvatore S.
2000-01-01
Hertsog Alfonso II d'Este sekretär Giovan Battista Nicolucci, hüüdnimega Pigna, 1561. a. Veneetsias ilm. sekretäriametnike õpperaamatust "Il Principe". Sekretäri ametinimetuse kujunemisest, töökohustustest ja ametist üldse
Nigro, Salvatore S.
2000-01-01
Hertsog Alfonso II d'Este sekretär Giovan Battista Nicolucci, hüüdnimega Pigna, 1561. a. Veneetsias ilm. sekretäriametnike õpperaamatust "Il Principe". Sekretäri ametinimetuse kujunemisest, töökohustustest ja ametist üldse
Bianchi Type-V Bulk Viscous Cosmic String in f(R,T Gravity with Time Varying Deceleration Parameter
Directory of Open Access Journals (Sweden)
Bïnaya K. Bishi
2015-01-01
Full Text Available We study the Bianchi type-V string cosmological model with bulk viscosity in f(R,T theory of gravity by considering a special form and linearly varying deceleration parameter. This is an extension of the earlier work of Naidu et al., 2013, where they have constructed the model by considering a constant deceleration parameter. Here we find that the cosmic strings do not survive in both models. In addition we study some physical and kinematical properties of both models. We observe that in one of our models these properties are identical to the model obtained by Naidu et al., 2013, and in the other model the behavior of these parameters is different.
Ho, Fei-Hung
2011-01-01
The Poincar\\'e gauge theory of gravity has a metric compatible connection with independent dynamics that is reflected in the torsion and curvature. The theory allows two good propagating spin-0 modes. Dynamical investigations using a simple expanding cosmological model found that the oscillation of the 0$^+$ mode could account for an accelerating expansion similar to that presently observed. The model has been extended to include a $0^{-}$ mode and more recently cross parity couplings. We investigate the dynamics of this model in a situation which is simple, non-trivial, and yet may give physically interesting results that might be observable. We consider homogeneous cosmologies, more specifically, isotropic Bianchi class A models. We find an effective Lagrangian for our dynamical system, a system of first order equations, and present some typical dynamical evolution.
Chaubey, R.; Shukla, A. K.; Raushan, Rakesh
2017-04-01
The general class of Bianchi cosmological models with dark energy in the form of modified Chaplygin gas with variable Λ and G and bulk viscosity have been considered. We discuss three types of average scale factor by using a special law for deceleration parameter which is linear in time with negative slope. The exact solutions to the corresponding field equations are obtained. We obtain the solution of bulk viscosity ( ξ), cosmological constant (Λ), gravitational parameter ( G) and deceleration parameter ( q) for different equations of state. The model describes an accelerating Universe for large value of time t, wherein the effective negative pressure induced by Chaplygin gas and bulk viscous pressure are driving the acceleration.
Pradhan, Anirudh; Jotania, Kanti
2009-01-01
A new class of LRS Bianchi type ${\\rm VI}_{0}$ cosmological models with free gravitational fields and a variable cosmological term is investigated in presence of perfect fluid as well as bulk viscous fluid. To get the deterministic solution we have imposed the two different conditions over the free gravitational fields. In first case we consider the free gravitational field as magnetic type whereas in second case `gravitational wrench' of unit `pitch" is supposed to be present in free gravitational field. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. The cosmological constant $\\Lambda$ is found to be a decreasing function of time and positive which is corroborated by results from recent supernovae Ia observations. The physical and geometric aspects of the models are discussed.
Institute of Scientific and Technical Information of China (English)
N. P. Gaikwad; M. S. Borkar; S. S. Charjan
2011-01-01
@@ We investigate the Bianchi type-I massive string magnetized barotropic perfect fluid cosmological model in Rosen's bimetric theory of gravitation with and without a magnetic field by applying the techniques used by Latelier(1979,1980) and Stachel(1983).To obtain a deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution.The physical and geometrical significance of the model are discussed.By comparing our model with the model of Bali et al.(2007), it is realized that there are no big-bang and big-crunch singularities in our model and T＝0 is not the time of the big bang, whereas the model of Bali et al.starts with a big bang at T=0.Further, our model is in agreement with Bali et al.(2007) as time increases in the presence, as well as in the absence, of a magnetic field.
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Ahmad T. Ali
2014-01-01
Full Text Available We find a new class of invariant inhomogeneous Bianchi type-I cosmological models in electromagnetic field with variable magnetic permeability. For this, Lie group analysis method is used to identify the generators that leave the given system of nonlinear partial differential equations (NLPDEs (Einstein field equations invariant. With the help of canonical variables associated with these generators, the assigned system of PDEs is reduced to ordinary differential equations (ODEs whose simple solutions provide nontrivial solutions of the original system. A new class of exact (invariant-similarity solutions have been obtained by considering the potentials of metric and displacement field as functions of coordinates x and t. We have assumed that F12 is only nonvanishing component of electromagnetic field tensor Fij. The Maxwell equations show that F12 is the function of x alone whereas the magnetic permeability μ¯ is the function of x and t both. The physical behavior of the obtained model is discussed.
String cosmology in LRS Bianchi type-II dusty Universe with time-decaying vacuum energy density
Indian Academy of Sciences (India)
Hassan Amirhashchi; Hosein Mohamadian
2012-04-01
A model of a cloud formed by massive strings is used as a source of LRS Bianchi type-II with time-decaying vacuum energy density . To construct string cosmological models, we have used the energy–momentum tensor for such strings as formulated by Letelier (1983). The high nonlinear ﬁeld equations have been solved for two types of strings: (i) massive string and (ii) Nambu string. The expansion in the model is assumed to be proportional to the shear . This condition leads to $A = B^m$, where and are the metric coefﬁcients, is a constant and is an integrating constant. Our models are in accelerating phase which is consistent with the recent observations of supernovae type-Ia. The physical and geometrical behaviour of these models are also discussed.
Agarwal, Shilpi; Pradhan, Anirudh
2010-01-01
The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological models representing massive strings in normal gauge for Lyra's manifold by applying the variation law for generalized Hubble's parameter that yields a constant value of deceleration parameter. The variation law for Hubble's parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's modified field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive string cosmological models for which we assume that the expansion ($\\theta$) in the model is proportional to the component $\\sigma^{1}_{~1}$ of the shear tensor $\\sigma^{j}_{i}$. This condition leads to $A = (BC)^{m}$, where A, B and C are the metric coefficients and m is proportionality cons...
为女人造梦的男人 专访La Perla设计总监Giovanni Bianchi
Institute of Scientific and Technical Information of China (English)
刘岩
2012-01-01
<正>他是内衣品牌设计总监;他是一个学法律的男人。照片中的他,艺术范儿地翘着脚望着天;眼前的他,西装笔挺笑容满面。他在我心中变成了两种极端相纠缠的统一,既难以相信又顺理成章。Giovanni Bianchi,La Perla全线产品的设计总监。他出生于意大利的Cesena,法律专业毕业后,开始在La Perla销售部门的工作。但是,他发现这不符合自己的创作天性,两年后,他决定转向设计,于是,移居巴黎同Jean Paul Gaultier一同工作。"Jean Paul Gaultier是我的职业导师,"在巴黎的工作和生活,让他的艺术天分茂盛地开花。也正是在这段时间里,Gaultier为麦当娜设计了那件惊艳世界的锥形胸衣。
Jamal, Sameerah; Shabbir, Ghulam
2017-02-01
We study the geometric properties of generators for the Klein-Gordon equation in Kantowski-Sachs and certain Bianchi-type spaces. Several versions of the Klein-Gordon equation are derived from its dependence on a potential function. The criteria for different versions of the (1+3) Klein-Gordon equation originates from analyzing three sources, viz. through generators that are identically the Killing algebra, or with the Killing vector fields that are recast into linear combinations and thirdly, real sub-algebras within the conformal algebra. In turn, these equations admit a catalogue of infinitesimal symmetries that are equivalent to the corresponding Killing vector fields in Kantowski-Sachs, Bianchi type III, IX, VIII, VI0 and VII0 space-times, with the exception of a linear vector W=upartialu in every case. The sheer number of results are displayed in appropriate tables. Subsequently, in application, we derive some Noetherian conservation laws and identify some exact solutions by quadratures.
Institute of Scientific and Technical Information of China (English)
R. K. Tiwari; Sonia Sharma
2011-01-01
We study the non existence of shear in locally rotationally symmetric Bianchi type-Ⅲ string cosmological models with bulk viscosity and variable cosmological term Λ. Exact solutions of the field equations are obtained by assuming the conditions: the bulk viscosity is proportional to the expansion scalar, ε ∝ θ, expansion scalar is proportional to shear scalar, θ ∝ σ, and Λ is proportional to the Hubble parameter. The coefficient of bulk viscosity is assumed to be a power function of mass density. The corresponding physical interpretations of the cosmological solutions are also discussed.%@@ We study the non existence of shear in locally rotationally symmetric Bianchi type-M string cosmological models with bulk viscosity and variable cosmological term Λ.Exact solutions of the field equations are obtained by assuming the conditions: the bulk viscosity is proportional to the expansion scalar, ξ∝θ, expansion scalar is proportional to shear scalar, θ∝σ, and A is proportional to the Hubble parameter.The coefficient of bulk viscosity is assumed to be a power function of mass density.The corresponding physical interpretations of the cosmological solutions are also discussed.
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Ayissi, Raoul Domingo, E-mail: raoulayissi@yahoo.fr; Noutchegueme, Norbert, E-mail: nnoutch@yahoo.fr [Department of Mathematics, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde (Cameroon)
2015-01-15
Global solutions regular for the Einstein-Boltzmann equation on a magnetized Bianchi type-I cosmological model with the cosmological constant are investigated. We suppose that the metric is locally rotationally symmetric. The Einstein-Boltzmann equation has been already considered by some authors. But, in general Bancel and Choquet-Bruhat [Ann. Henri Poincaré XVIII(3), 263 (1973); Commun. Math. Phys. 33, 83 (1973)], they proved only the local existence, and in the case of the nonrelativistic Boltzmann equation. Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academy of Science, 2000), Vol. 52] obtained a global existence result, for the relativistic Boltzmann equation coupled with the Einstein equations and using the Yosida operator, but confusing unfortunately with the nonrelativistic case. Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)] and Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], have obtained a global solution in time, but still using the Yosida operator and considering only the uncharged case. Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)] also proved a global existence of solutions to the Maxwell-Boltzmann system using the characteristic method. In this paper, we obtain using a method totally different from those used in the works of Noutchegueme and Dongho [Classical Quantum Gravity 23, 2979 (2006)], Noutchegueme, Dongho, and Takou [Gen. Relativ. Gravitation 37, 2047 (2005)], Noutchegueme and Ayissi [Adv. Stud. Theor. Phys. 4, 855 (2010)], and Mucha [Global existence of solutions of the Einstein-Boltzmann equation in the spatially homogeneous case. Evolution equation, existence, regularity and singularities (Banach Center Publications, Institute of Mathematics, Polish Academy of Science, 2000), Vol. 52] the
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Matteo Moca
2017-06-01
In tale ottica diventa allora interessante indagare le forme che le parole di un'opera assumono, per valutare quanto la parola scritta ricalchi o meno la parola piena, anche nel suo rapporto con il fruitore diretto, il lettore, che assume un ruolo che, forzando i termini del paragone, potremmo definire quasi di psicoanalista, in quanto si mette nella posizione di ascoltatore e interprete della parola. E così come per lo psicoanalista, la sua funzione sarà quella di riempire i blanks, gli spazi bianchi di cui parla Wolfgang Iser, alla ricerca dell'interpretazione. In alcuni casi, lo stesso atto della scrittura sarà un tentativo di far assumere alla parola quella intersoggettività che la rende piena, in altre invece spetterà al lettore-psicoanalista lo sforzo di riempire di significato i blanks, gli spazi vuoti della parola perché, come suggerisce Roland Barthes, «tutta la moneta logica è negli interstizi». Così diviene interessante l'utilizzo di una teoria critica che, attraverso gli strumenti della psicoanalisi lacaniana e dei paradigmi di Iser, tenti un'analisi comparata dei diari di Tommaso Landolfi e del romanzo pseudo-autobiografico W ou le souvenir d'enfance di Georges Perec. In queste due opere infatti i confini tra i ruoli di autore, personaggio e lettore sono molto sfumati e la scrittura è scissa in due parti: una più immediatamente indagabile, l'altra invece tentativo di narrare il bianco che accompagna la memoria e la scrittura e che, attraverso questo metodo, il critico può tentare di riempire.
Bradas, James C.; Fennelly, Alphonsus J.; Smalley, Larry L.
1987-01-01
It is shown that a generalized (or 'power law') inflationary phase arises naturally and inevitably in a simple (Bianchi type-I) anisotropic cosmological model in the self-consistent Einstein-Cartan gravitation theory with the improved stress-energy-momentum tensor with the spin density of Ray and Smalley (1982, 1983). This is made explicit by an analytical solution of the field equations of motion of the fluid variables. The inflation is caused by the angular kinetic energy density due to spin. The model further elucidates the relationship between fluid vorticity, the angular velocity of the inertially dragged tetrads, and the precession of the principal axes of the shear ellipsoid. Shear is not effective in damping the inflation.
Institute of Scientific and Technical Information of China (English)
白明; 张岗; 张敬悌; 葛文安; 王盛兴
2012-01-01
目的 探讨改良Bianchi(阴囊中缝单一切口)手术治疗低位双侧隐睾的可行性、手术操作要点以及近期效果.方法 2010年9月至2011年5月采用改良Bianchi术式治疗先天性双侧隐睾共9例,年龄1岁2个月至11岁4个月,平均5岁10个月.所有患儿平卧位均可在腹股沟区触及未降的睾丸.术前B超均未提示合并鞘膜积液或者斜疝.手术采取经阴囊中缝切口入路,将睾丸鞘膜囊分离至外环水平,如鞘状突呈开放状,则完整分离鞘突并充分游离至高位后双层结扎.根据精索松解的具体情况采取保留或切断睾丸引带,术后睾丸均位于各自阴囊中部或底部.术后2～3 d换药,伤口无渗出、红肿即可出院.所有患儿平均随访8个月.观察手术前后睾丸体积变化,睾丸有无回缩,有无斜疝或鞘膜积液等并发症,家长和(或)患儿本身是否满意.睾丸体积根据B超数据使用Lambert公式进行计算.结果 9例患儿均顺利完成手术,所有睾丸术后位置满意,无回缩,无斜疝或鞘膜积液等并发症.手术前后体积比较未见萎缩(P＜0.01),家长及患儿均对手术效果表示满意.结论 改良Bianchi手术治疗可触及隐睾损伤小,伤口隐蔽性很强、符合微创理念.尤其是在治疗双侧的低位以及滑动性隐睾时有较好的安全性和可操作性,中短期随访无并发症,有一定的临床运用价值.%Objective To explore the feasibility, surgical techniques and efficacy of modified Bianchi (single incision on scrotal median line) orchiopexy in children with low bilateral undescended testes. Methods From September 2010 to May 2011, 9 children aging from 14 to 136 months (average 70 months) with congenital bilateral undescended testes underwent modified Bianchi procedure in our department. The testis of them could be touched in groin area in supine position; hydrocele and hernia were not complicated in them via pre-operative ultrasonic examination. Operation was
On Latin-Protoslavic Language Contacts. Some Remarks on a Recent Paper by Salvatore Del Gaudio
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Raffaele Caldarelli
2015-01-01
Full Text Available The Author discusses a recent paper by Del Gaudio concerning the problem of Latin and Protoromance borrowings in Protoslavic and Old Church Slavonic. He appreciates Del Gaudio’s attempt to illustrate the historical frame of Latin/Romance – Slavic linguistic contact in a deeper and more insightful way, but criticizes several statements regarding mainly: a certain methodological issues concerning Protoslavic and his reconstruction; b linguistic relations between the Slavs and other ethno-linguistic groups within the Indo-European family; c some controversial phonological questions involving lexical items borrowed by the Slavs; d the treatment of eleven Old Church Slavonic lexical items allegedly directly borrowed from Latin.
Is the Bianchi identity always hyperbolic?
Rácz, István
2014-01-01
We consider $n+1$ dimensional smooth Riemannian and Lorentzian spaces satisfying Einstein's equations. The base manifold is assumed to be smoothly foliated by a one-parameter family of hypersurfaces. In both cases---likewise it is usually done in the Lorentzian case---Einstein's equations may be split into `Hamiltonian' and `momentum' constraints and a `reduced' set of field equations. It is shown that regardless whether the primary space is Riemannian or Lorentzian whenever the foliating hypersurfaces are Riemannian the `Hamiltonian' and `momentum' type expressions are subject to a subsidiary first order symmetric hyperbolic system. Since this subsidiary system is linear and homogeneous in the `Hamiltonian' and `momentum' type expressions the hyperbolicity of the system implies that in both cases the solutions to the `reduced' set of field equations are also solutions to the full set of equations provided that the constraints hold on one of the hypersurfaces foliating the base manifold.
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Floriana Iannone
2016-06-01
Full Text Available I musei d’impresa rappresentano una forma di memoria organizzativa che può e deve essere usata in maniera consapevole per lo sviluppo e la comunicazione dell’identità e dell’immagine dell’impresa. Oggetto del lavoro è l’analisi del ruolo strategico che il museo può assumere come strumento di narrazione dell’identità d’impresa. Il framework teorico è basato sui costrutti dell’identità organizzativa e del sensemaking nonché sul paradigma narrativo. In particolare, l’indagine esplorativa chiarisce la natura e il contenuto dell’identità organizzativa della Ferragamo SpA, considerando il museo d’impresa come asset in grado di comunicare ed esaltare i valori identitari dell’impresa. Ferragamo rappresenta un exemplum di come un’impresa heritage-based possa adoperare la storia nella “narrazione” allo scopo di dialogare con i suoi stakeholders esterni e interni rafforzando autenticità e credibilità nel marchio. The paper assumes that corporate museums are a form of organizational memory to be strategically used for the development and the communication of a company’s identity and image. Object of the work is the analysis of corporate museum’s strategic role in telling the company. The theoretical framework is based on organizational identity and sensemaking topics together with the narrative paradigm. The exploratory study clarifies the organizational identity nature of the Ferragamo SpA, considering the corporate museum as an asset communicating what is core about the company. Ferragamo can be considered as an exemplum of how a heritage based company can manage the story in “narrative” in order to communicate to its external and internal stakeholders reinforcing the authenticity and the credibility of the brand.
Oscillatory singularities in Bianchi models with magnetic fields
Liebscher, Stefan; Tchapnda, Sophonie Blaise
2012-01-01
An idea which has been around in general relativity for more than forty years is that in the approach to a big bang singularity solutions of the Einstein equations can be approximated by the Kasner map, which describes a succession of Kasner epochs. This is already a highly non-trivial statement in the spatially homogeneous case. There the Einstein equations reduce to ordinary differential equations and it becomes a statement that the solutions of the Einstein equations can be approximated by heteroclinic chains of the corresponding dynamical system. For a long time progress on proving a statement of this kind rigorously was very slow but recently there has been new progress in this area, particularly in the case of the vacuum Einstein equations. In this paper we generalize some of these results to the Einstein-Maxwell equations. It turns out that this requires new techniques since certain eigenvalues are in a less favourable configuration in the case with a magnetic field. The difficulties which arise in tha...
A Dynamical Systems Approach to Geodesics in Bianchi Cosmologies
Nilsson, Ulf S.; Uggla, Claes; Wainwright, John
2000-10-01
To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null geodesics. Dynamical systems theory, in conjunction with the orthonormal frame approach, has proved to be an invaluable tool for analyzing spatially homogeneous cosmologies. It is thus natural to use such techniques to study the geodesics of these models. We therefore augment the Einstein field equations with the geodesic equations, all written in dimensionless form, obtaining an extended system of first-order ordinary differential equations that simultaneously describes the evolution of the gravitational field and the behavior of the associated geodesics. It is shown that the extended system is a powerful tool for investigating the effect of space-time anisotropies on the temperature of the cosmic microwave background radiation, and that it can also be used for studying geodesic chaos.
Bianchi $VII_A$ solutions of quadratic gravity
de Deus, Juliano A
2011-01-01
It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "open" model $H^ 3$ for this effective gravity are given. It must be emphasized that although numeric, these solutions are exact in the sense that they depend only on the precision of the machine. The solutions are identified asymptotically in a certain sense. It is found solutions which asymptote de Sitter space, Minkowski space and a singularity.
The Bianchi classification of maximal D=8 gauged supergravities
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Bergshoeff, E.; Nielsen, M.; Roest, D. [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Gran, U. [Department of Mathematics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Linares, R. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, A.P. 55-534, Mexico D.F. (Mexico); Ortin, T. [Instituto de Fisica Teorica, C-XVI, Universidad Autonoma de Madrid, 28049 Madrid (Spain)
2004-06-01
The class A theories have 1/2 BPS domain wall solutions that uplift to purely gravitational solutions consisting of 7D Minkowski and a 4D Euclidean geometry. These geometries are generically singular. The two regular exceptions correspond to the near-horizon limit of the single-center or double-centered Kaluza-Klein monopole. In contrast, the class B supergravities are defined by a set of equations of motion that cannot be integrated to an action and allow for no 1/2 BPS domain walls. (Abstract Copyright [2004], Wiley Periodicals, Inc.)
Global Dynamics, Blow-Up, and Bianchi Cosmology
Ben-Gal, Nitsan; Buchner, Johannes; Hell, Juliette; Karnauhova, Anna; Liebscher, Stefan; Rendall, Alan; Smith, Brian; Stuke, Hannes; Väth, Martin; Fiedler, Bernold
2016-01-01
Many central problems in geometry, topology, and mathematical physics lead to questions concerning the long-time dynamics of solutions to ordinary and partial differential equations. Examples range from the Einstein field equations of general relativity to quasilinear reaction-advection-diffusion equations of parabolic type. Specific questions concern the convergence to equilibria, the existence of periodic, homoclinic, and heteroclinic solutions, and the existence and geometric structure of global attractors. On the other hand, many solutions develop singularities in finite time. The singularities have to be analyzed in detail before attempting to extend solutions beyond their singularities, or to understand their geometry in conjunction with globally bounded solutions. In this context we have also aimed at global qualitative descriptions of blow-up and grow-up phenomena.
Factors influencing choice of chemotherapy in metastatic colorectal cancer (mCRC
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Rossi L
2013-11-01
Full Text Available Luigi Rossi, Foteini Vakiarou, Federica Zoratto, Loredana Bianchi, Anselmo Papa, Enrico Basso, Monica Verrico, Giuseppe Lo Russo, Salvatore Evangelista, Guilia Rinaldi, Francesca Perrone-Congedi, Gian Paolo Spinelli, Valeria Stati, Davide Caruso, Alessandra Prete, Silverio TomaoDepartment of Medico-Surgical Sciences and Biotechnologies, "Sapienza" University of Rome, Rome, Italy; Oncology Unit, ICOT, Latina, ItalyAbstract: Management of metastatic colorectal cancer requires a multimodal approach and must be performed by an experienced, multidisciplinary expert team. The optimal choice of the individual treatment modality, according to disease localization and extent, tumor biology, and patient clinical characteristics, will be one that can maintain quality of life and long-term survival, and even cure selected patients. This review is an overview of the different therapeutic approaches available in metastatic colorectal cancer, for the purpose of defining personalized therapeutic algorithms according to tumor biology and patient clinical features.Keywords: metastatic colorectal cancer, patient clinical features, tumor biology, multidisciplinary approach
品质至上-沙华多利意大大利餐厅%Quality Paramount-Pasta Fresca Da Salvatore
Institute of Scientific and Technical Information of China (English)
余晶
2007-01-01
@@ 没有法国的繁文缛节,也不像美国的快餐文化,若说意大利菜是为美食而诞生并不为过.意大利人深谙饮食之道,饮食是意大利人生活中的一大乐趣,正如加菲猫所说:意大利面是一种生活态度.
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Fabio Cusimano
2012-06-01
Full Text Available La diffusione del libro nel Medioevo potrebbe essere riletta alla luce di una metafora attuale sebbene non scevra di aspetti dialettici: quella della “rete”. All’ubicazione spazio-temporale del libro nei monasteri medievali, contraddistinta da fisicità e permanenza, si sotituisce oggi un formato digitale e virtuale, che porta ad una sorta di decontestualizzazione e alla continuità del flusso di informazioni, contribuendo alla diffusione capillare del sapere. L’ottica di universalità e globalità accomuna tuttavia entrambe le epoche. Alcuni concetti-chiave dell’informatica potrebbero infatti declinarsi in ambito medievale: Server-Client per la raccolta, la conservazione e la trasmissione delle conoscenze da parte dei monasteri, quali centri del sapere in Europa, agli uomini di cultura; Firewall, per alludere alla necessità di tutelare i manoscritti, mediante la copiatura e la diffusione dei codici; Community, ad indicare non solo la comunità religiosa o monastica in senso stretto, bensì l’apertura ad una costruzione del sapere mediante un’azione partecipativa. I problemi dell’autenticità delle fonti, dell’acriticità delle informazioni e la pratica delle citazioni trovano un precedente significativo nelle Sententiae di Pietro Lombardo: una sorta di “biblioteca virtuale” grazie alla collezione di passi dalla Sacra Scrittura e da fonti latine e greche, paragonabile a un moderno modello enciclopedico di sapere. The diffusion of the book in the Middle Ages could be critically read through a modern metaphor: the “net”. The space-temporal coordinates of the book shift from being physical and permanent in the Medieval monasteries, to being de-contextualized and continue in the flow of information of digital and virtual format. However the universal and global perspective is common to the contemporary and the Medieval periods. In fact some key-words of computer science could be applied to the Medieval context: Server-Client, for the collection, the preservation and the transmission of knowledge from monasteries, as cultural centers in Medieval Europe, to men of culture; Firewall, for the necessary protection of manuscripts, through copying and diffusing codes; Community, referred not only to the monastic and religious groups, but also to an open sharing of the building of knowledge. Problems like the authenticity of the sources, the lack of criticality in the reception of data, and the practice of quotations are well represented in Peter Lombard’s Sententiae: this work can be compared to a modern encyclopedia thanks to the collection of passages from the Holy Scripture and from Latin and Greek sources, as well as a “virtual library”.
Equilibrium points of the tilted perfect fluid Bianchi VIh state space
Apostolopoulos, Pantelis S.
2005-05-01
We present the full set of evolution equations for the spatially homogeneous cosmologies of type VIh filled with a tilted perfect fluid and we provide the corresponding equilibrium points of the resulting dynamical state space. It is found that only when the group parameter satisfies h > -1 a self-similar solution exists. In particular we show that for h > -{1/9} there exists a self-similar equilibrium point provided that γ ∈ ({2(3+sqrt{-h})/5+3sqrt{-h}},{3/2}) whereas for h VIh.
Bianchi - Euler system for relativistice fluids and Bel - Robinson type energy
Choquet-Bruhat, Y; Choquet-Bruhat, Yvonne; York, James W.
2002-01-01
We write a first order symmetric hyperbolic system coupling the Riemann with the dynamical acceleration of a relativistic fluid. W determine the associated, coupled, Bel - Robinson energy, and the integral equality that it satisfies.
Uniqueness of the Fock quantization of scalar fields in a Bianchi I cosmology with unitary dynamics
Cortez, Jerónimo; Martín-Benito, Mercedes; Marugán, Guillermo A Mena; Olmedo, Javier; Velhinho, José M
2016-01-01
The Fock quantization of free scalar fields is subject to an infinite ambiguity when it comes to choosing a set of annihilation and creation operators, choice that is equivalent to the determination of a vacuum state. In highly symmetric situations, this ambiguity can be removed by asking vacuum invariance under the symmetries of the system. Similarly, in stationary backgrounds, one can demand time-translation invariance plus positivity of the energy. However, in more general situations, additional criteria are needed. For the case of free (test) fields minimally coupled to a homogeneous and isotropic cosmology, it has been proven that the ambiguity is resolved by introducing the criterion of unitary implementability of the quantum dynamics, as an endomorphism in Fock space. This condition determines a specific separation of the time dependence of the field, so that this splits into a very precise background dependence and a genuine quantum evolution. Furthermore, together with the condition of vacuum invaria...
Bianchi Type-Ⅴ Bulk Viscous Barotropic Fluid Cosmological Model with Variable G and A
Institute of Scientific and Technical Information of China (English)
Raj Bali; Seema Tinker
2008-01-01
@@ We investigate the Bianehi type-Ⅴ bulk viscous barotropic fluid cosmological model with variable gravitational constant G and the cosmological constant A, assuming the condition on metric potential as A/A=B/B=C/C=m/ln, where A, B, and C are functions of time t, while m and n are constants. To obtain the deterministic model, we also assume the relations P= p-3ηH, p =γρ, η = ηoρs, where p is the isotropic pressure, η the bulk viscosity, 0 ≤γ≤1, H the Hubble constant, ηo and s are constants. Various physical aspects of the model are discussed. The case of n = 1 is also discussed to compare the results with the actual universe.
On the origins of organology: Franz Joseph Gall and a girl named Bianchi
Eling, P.A.T.M.; Finger, S.; Whitaker, H.A.
2017-01-01
Franz Joseph Gall (1758-1828) introduced a new theory of mind and brain at the end of the eighteenth century, which he referred to as organology, dealing with mental functions and their cortical localizations. Gall wrote that observations regarding the verbal learning capacities of his schoolmates b
Thermodynamics of Interacting new Agegraphic Dark Energy and Dark Matter Due to Bianchi Type I Model
Hossienkhani, Hossien
2016-11-01
We study a thermodynamical description of the interaction between new agegraphic dark energy (NADE) and dark matter (DM) in an anisotropic universe. We find expressions for the entropy changes of these dark energy (DE) candidates. In addition, considering thermal fluctuations, thermodynamics of the DE component interacting with a DM sector is addressed. We also show that if one wants to solve the coincidence problem by using this mutual interaction, then the coupling constants of the interaction will be constrained. Finally, we obtain a physical expression for the interaction which is consistent with phenomenological descriptions and passes reasonably well the observational tests. Our study shows that, with the local equilibrium assumption, the generalized second law of thermodynamics is fulfilled in a region enclosed by the apparent horizon.
Non-Commutative Worlds - Classical Constraints, Relativity and the Bianchi Identity
Kauffman, Louis H
2011-01-01
This paper shows how discrete measurement leads to commutators and how discrete derivatives are naturally represented by commutators in a non-commutative extension of the calculus in which they originally occurred. We show how the square root of minus one (i) arises naturally as a time-sensitive observable for an elementary oscillator. In this sense the square root of minus one is a clock and/or a clock/observer. This sheds new light on Wick rotation, which replaces t (temporal quantity) by it. In this view, the Wick rotation replaces numerical time with elementary temporal observation. The relationship of this remark with the Heisenberg commutator [P,Q]=ihbar is explained in the Introduction. After a review of previous work, the paper begins with a section of iterants - a generalization of the complex numbers as described above. This generalization includes all of matrix algebra in a temporal interpretation. We then give a generalization of the Feynman-Dyson derivation of electromagnetism in the context of n...
Palatini–Lovelock–Cartan gravity—Bianchi identities for stringy fluxes
Blumenhagen, R.; Deser, A.; Plauschinn, E.; Rennecke, F.
2012-01-01
A Palatini-type action for Einstein and Gauss–Bonnet gravity with non-trivial torsion is proposed. A three-form flux is incorporated via a deformation of the Riemann tensor, and consistency of the Palatini variational principle requires the flux to be covariantly constant and to satisfy a Jacobi ide
On Theorem 2.3 in "Prediction, Learning, and Games" by Cesa-Bianchi and Lugosi
Chernov, Alexey
2010-01-01
The note presents a modified proof of a loss bound for the exponentially weighted average forecaster with time-varying potential. The regret term of the algorithm is upper-bounded by sqrt{n ln(N)} (uniformly in n), where N is the number of experts and n is the number of steps.
La decolonizzazione e l'indipendenza del Mozambico: coloni bianchi e movimenti nazionalisti
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Fernando Tavares Pimenta
2016-12-01
Full Text Available The essay analyzes the historical process of independence of Mozambique, especially the political behavior of the white population during the phase of decolonization (1974/1975. We will analyze the different forms of decolonization and the different positions of various political factions and groups within the white community, as well as the positions taken by the Portuguese State, as a colonial power, and by Frelimo, as the main nationalist movement. Our goal is to understand the evolution of the independence process from the inside of colonial society and, at the same time, understand the reasons of the rebellion of September 7, 1974, of the exclusion of the white population from politics and of its flight abroad in August 1974.
Bianchi type I Universe and interacting ghost scalar fields models of dark energy
Hossienkhani, H.
2016-04-01
We suggest a correspondence between interacting ghost dark energy model with the quintessence, tachyon and K-essence scalar field in a non-isotropic universe. This correspondence allows to reconstruct the potential and the dynamics for the scalar field of the interacting ghost dark energy model, which describe accelerated expansion of the universe. Our numerical result show the effects of the interaction and anisotropic on the evolutionary behavior the ghost scalar field models.
Energy Momentum Localization for Bianchi I-III-V-VI0 Universe in Teleparallel Gravity
Aygun, Sezgin; Aygun, Melis; Tarhan, Ismail
2006-01-01
This paper has been removed by arXiv administrators because it plagiarizes gr-qc/0010068. This paper has excessive overlap with the following papers also written by the authors or their collaborators: gr-qc/0607109, gr-qc/0607126, gr-qc/0607103, gr-qc/0607115, gr-qc/0607119, gr-qc/0608024, gr-qc/0601133, gr-qc/0603044, gr-qc/0607089, gr-qc/0505078, and others.
Energy Momentum Complexes For Bianchi Type II-VIII-IX Universes
Aygun, Sezgin; Aygun, Melis; Tarhan, Ismail
2006-01-01
This paper has been removed by arXiv administrators because it plagiarizes gr-qc/0303009, hep-th/0405047, gr-qc/0412120, gr-qc/0602107, hep-th/0311050, and gr-qc/0508005. This paper has excessive overlap with the following papers also written by the authors or their collaborators: gr-qc/0607119, gr-qc/0607103, gr-qc/0607126, gr-qc/0606080, gr-qc/0607102, gr-qc/0510123, gr-qc/0607110, and others.
Kuusk, Priit, 1938-
2001-01-01
Festivalidest ئ Drottningholmi lossifestivalist, Verdi festivalidest San Francisco Ooperis ja Taani Kunglikus Ooperis, Glyndebourne'i ooperifestivalist. B.Skride võitis Kuninganna Elisabethi nim. rahvusvahelise viiuldajate konkursi. Saksamaal Gütersloh's toimunud Bertelsmanni Fondi korraldatatava lauljate rahvusvahelise konkursi laureaatidest. S.Licitra on tõusev täht tenorite seas. R.Sirkiä valiti Savonlinna ooperifestivalide uueks kunstiliseks juhiks alates 2003. aastast
Cerezo Sánchez, Rosario
2016-01-01
OBJETIVOS: Esta tesis se enmarca en el ámbito de la Pervivencia de la Mitología Clásica y el objetivo es investigar sobre el tratamiento e influencia que la leyenda de Andrómeda y Perseo ha tenido a lo largo de tres periodos histórico-musicales en la ópera: barroco, clasicismo y siglo XX. El origen de este trabajo es la lectura de la leyenda de Andrómeda y Perseo en la versión canónica de Ovidio en las Metamorfosis, 4.604-803 y 5.1-235. Nuestro objetivo es examinar la proyección de ...
Sardiinia kirjandus kui hea idee
2007-01-01
Toimetuse artikkel Elsbeth Gut Bozzetti artikli "Vana maailm ja uus laine" (Alte Welt und neue Welle. - Neue Zürcher Zeitung 16.12. 2006) ning internetis avaldatud materjali põhjal. Gavino Ledda, Salvatore Satta, Salvatore Niffoi jt.
Sardiinia kirjandus kui hea idee
2007-01-01
Toimetuse artikkel Elsbeth Gut Bozzetti artikli "Vana maailm ja uus laine" (Alte Welt und neue Welle. - Neue Zürcher Zeitung 16.12. 2006) ning internetis avaldatud materjali põhjal. Gavino Ledda, Salvatore Satta, Salvatore Niffoi jt.
Patrice Loïez
2002-01-01
Photo 01 : Prof. Roger Cashmore, Research Director for Collider Programmes, Dr Salvatore Castorina, Corporate Vice President, DSG, Prof. Gigi Rolandi, CMS Tracker Project Manager. Photo 02 : Dr Salvatore Castorina signing the Guest Book. Photo 03 : Prof. Roger Cashmore, Dr Salvatore Castorina.
Study on Vector Inflation in Bianchi Type I Cosmology%Bianchi I型宇宙中矢量暴涨理论相关问题的研究
Institute of Scientific and Technical Information of China (English)
董义乔; 张笋
2010-01-01
通过矢量暴涨理论,研究了与之相关的问题,特别是粒子生成对慢滚过程、相图以及各向异性的影响.计算结果表明,粒子生成对标量场的影响使得相图上出现一个峰,峰的方向不受初始条件和质量改变的影响.而对于矢量场,情况则不同,粒子生成对应的峰其方向会改变,这与质量的变化有关.相应地,体系的各向异性也会随之增强或减弱.各向异性的程度不仅决定于慢滚过程,还决定于慢滚后的粒子生成过程.粒子生成可以成为宇宙各向同性化的原因.
Directory of Open Access Journals (Sweden)
Nora Lafi
2004-11-01
Full Text Available L'histoire de la colonisation italienne en Méditerranée s'enrichit de nouveau avec ce bel ouvrage intitulé Oasis d'italianité, la Libye de la colonisation agraire entre fascisme, guerre et indépendance (1935-1956. Ce livre constitue une étape majeure dans l'historiographie italienne, dans le sens où il marque une évolution dans les études sur la colonisation italienne. Celles-ci furent souvent traitées sur le mode de l'événementiel et du général, exceptions faites de la thèse non publiée de ...
Stemcell Information: SKIP000915 [SKIP Stemcell Database[Archive
Lifescience Database Archive (English)
Full Text Available s Immunostaining ... Yes Teratoma formation ... Salvatore Iovino Salvatore Iovino Harvard... Medical School Harvard Medical School Harvard Medical School Harvard Medical School C. Rona...ld Kahn C. Ronald Kahn Not Available Harvard Medical School Harvard Medical School ... 26831110 10.1073/pna
Stemcell Information: SKIP000913 [SKIP Stemcell Database[Archive
Lifescience Database Archive (English)
Full Text Available unostaining ... Yes Teratoma formation ... Salvatore Iovino Salvatore Iovino Harvard... Medical School Harvard Medical School Harvard Medical School Harvard Medical School C. Ronald Ka...hn C. Ronald Kahn Not Available Harvard Medical School Harvard Medical School ... 26831110 10.1073/pnas.152
Stemcell Information: SKIP000912 [SKIP Stemcell Database[Archive
Lifescience Database Archive (English)
Full Text Available ing ... Yes Teratoma formation ... Salvatore Iovino Salvatore Iovino Harvard Medical School Harvar...d Medical School Harvard Medical School Harvard Medical School C. Ronald Kahn C. Ro...nald Kahn Information Only Harvard Medical School Harvard Medical School ... 26831110 10.1073/pnas.15256651
Stemcell Information: SKIP000914 [SKIP Stemcell Database[Archive
Lifescience Database Archive (English)
Full Text Available ining ... Yes Teratoma formation ... Salvatore Iovino Salvatore Iovino Harvard Medical School Harv...ard Medical School Harvard Medical School Harvard Medical School C. Ronald Kahn C. ...Ronald Kahn Not Available Harvard Medical School Harvard Medical School ... 26831110 10.1073/pnas.152566511
L'università del futuro il ruolo della ricerca
Settis, Salvatore
2004-01-01
Relazione svolta dal Prof. Salvatore Settis, Direttore della Scuola Normale Superiore di Pisa, in occasione della cerimonia della consegna dei diplomi ai dottori di ricerca dell'Università degli Studi di Milano.
Vaus-Tamm, Heili, 1961-
2003-01-01
Uutest plaatidest The Dowland Project "Care-charming sleep John Potter", Clem Snide "Soft Spot", Deep Purple " Bananas", Don Johnson Big Band "Breaking Daylight", Duetto "Marcelo Alvarez, Salvatore Licitra", Sting "Sacred Love", Travis "12 Memories"
Vaus-Tamm, Heili, 1961-
2003-01-01
Uutest plaatidest The Dowland Project "Care-charming sleep John Potter", Clem Snide "Soft Spot", Deep Purple " Bananas", Don Johnson Big Band "Breaking Daylight", Duetto "Marcelo Alvarez, Salvatore Licitra", Sting "Sacred Love", Travis "12 Memories"
30. III avati rahvusraamatukogu VI korruse trepigaleriis...
2004-01-01
Näitus "Euroopa XVII sajandi sügavtrükigraafika Eesti Rahvusraamatukogus". Avamisele eelnes kuraator Jüri Haini loeng. Kunstnike hulgas on prantslased Jacques Callot, Claude Vignon, itaallased Salvatore Rosa, Stefano della Bella jt.
Pegylated liposomal doxorubicin in the management of ovarian cancer
Ferrandina, Gabriella
2010-01-01
Gabriella Ferrandina1,2, Giacomo Corrado1, Angelo Licameli1, Domenica Lorusso2, Gilda Fuoco1, Salvatore Pisconti3, Giovanni Scambia2 1Gynecologic Oncology Unit, Department of Oncology, Catholic University of Campobasso, Campobasso, Italy; 2Gynecologic Oncology Unit, Catholic University of Rome, Rome, Italy; 3Salvatore Pisconti, Oncology Unit, Taranto Hospital, Taranto, Italy Abstract: Among the pharmaceutical options available for treatment of ovarian cancer, much attention has been progressi...
Marked increase in substance use among young people after L?Aquila earthquake
Pollice, Rocco; Bianchini, Valeria; Roncone, Rita; Casacchia, Massimo
2011-01-01
Marked increase in substance use among young people after L?Aquila earthquake (Pollice, Rocco) Department of Health Sciences, Psychiatric Unit, `San Salvatore? Hospital, University of L?Aquila - L?Aquila - ITALY (Pollice, Rocco) Department of Health Sciences, Psychiatric Unit, University of L?Aquila - Via Vetoio, Loc. Coppito - 67100 - L?Aquila - ITALY (Pollice, Rocco) Department of Health Sciences, Psychiatric Unit, `San Salvatore? Hospital, Universi...
Linear perturbations of spatially locally homogeneous spacetimes
Tanimoto, M
2003-01-01
Methods and properties regarding the linear perturbations are discussed for some spatially closed (vacuum) solutions of Einstein's equation. The main focus is on two kinds of spatially locally homogeneous solution; one is the Bianchi III (Thurston's H^2 x R) type, while the other is the Bianchi II (Thurston's Nil) type. With a brief summary of previous results on the Bianchi III perturbations, asymptotic solutions for the gauge-invariant variables for the Bianchi III are shown, with which (in)stability of the background solution is also examined. The issue of linear stability for a Bianchi II solution is still an open problem. To approach it, appropriate eigenfunctions are presented for an explicitly compactified Bianchi II manifold and based on that, some field equations on the Bianchi II background spacetime are studied. Differences between perturbation analyses for Bianchi class B (to which Bianchi III belongs) and class A (to which Bianchi II belongs) are stressed for an intention to be helpful for applic...
Gruetzmann, Melchior
2014-01-01
Starting with minimal requirements from the physical experience with higher gauge theories, i.e. gauge theories for a tower of differential forms of different form degrees, we discover that all the structural identities governing such theories can be concisely recombined into a so-called Q-structure or, equivalently, a Lie infinity algebroid. This has many technical and conceptual advantages: Complicated higher bundles become just bundles in the category of Q-manifolds in this approach (the many structural identities being encoded in the one operator Q squaring to zero), gauge transformations are generated by internal vertical automorphisms in these bundles and even for a relatively intricate field content the gauge algebra can be determined in some lines only and is given by the so-called derived bracket construction. This article aims equally at mathematicians and theoretical physicists; each more physical section is followed by a purely mathematical one. While the considerations are valid for arbitrary hig...
Grützmann, Melchior; Strobl, Thomas
2015-10-01
Starting with minimal requirements from the physical experience with higher gauge theories, i.e. gauge theories for a tower of differential forms of different form degrees, we discover that all the structural identities governing such theories can be concisely recombined into what is called a Q-structure or, equivalently, an L∞-algebroid. This has many technical and conceptual advantages: complicated higher bundles become just bundles in the category of Q-manifolds in this approach (the many structural identities being encoded in the one operator Q squaring to zero), gauge transformations are generated by internal vertical automorphisms in these bundles and even for a relatively intricate field content the gauge algebra can be determined in some lines and is given by what is called the derived bracket construction. This paper aims equally at mathematicians and theoretical physicists; each more physical section is followed by a purely mathematical one. While the considerations are valid for arbitrary highest form degree p, we pay particular attention to p = 2, i.e. 1- and 2-form gauge fields coupled nonlinearly to scalar fields (0-form fields). The structural identities of the coupled system correspond to a Lie 2-algebroid in this case and we provide different axiomatic descriptions of those, inspired by the application, including e.g. one as a particular kind of a vector-bundle twisted Courant algebroid.
Directory of Open Access Journals (Sweden)
Marco Viglietti
2011-03-01
Full Text Available
Questo lavoro si inserisce nell’ambito delle indagini archeologiche compiute tra il 2002 e il 2008 nell’area delle caserme “G. Carreca” e “Ce.Ri.co.”, in via Labicana a Roma. Ad una prima strutturazione dell’area di età domizianea, seguono fasi di vita di età antonina e severiana, prima dell’ultima, grande fase edificatoria riferibile alla seconda metà del IV - V secolo. La nostra indagine si appunta sul consistente deposito di marmi da opus sectile pavimentale e parietale. Specchio di un’elevata committenza, costituisce un campionario delle forme decorative in uso a Roma tra il I e il IV - V secolo.
This work develops from the archaeological researches carried out between 2002 and 2008 in Rome, via Labicana, in the area of “G. Carreca” and “Ce.Ri.co.” barracks. These the phases recognized: late Flavian, Antonine and Severiane, before the latest in the second half of IV/V cent. A.D. The survey focus on a considerable marble’s deposit in the kind of pavimental and parietal opus sectile. It’s a mark of an elevated customer and it represents a decorative shapes set of samples in use at Rome between I and IV-V cent. A.D.
Lecian, Orchidea Maria
2013-01-01
The Selberg trace formula is specified for cosmological billiards in $4=3+1$ spacetime dimensions. The spectral formula is rewritten as an exact sum over the initial conditions for the Einstein field equations for which periodic orbits are implied. For this, a suitable density of measure invariant under the billiard maps has been defined, within the statistics implied by the BKL paradigm. The trace formula has also been specified for the stochastic limit of the dynamics, where the sum over initial conditions has been demonstrated to be equivalent to a sum over suitable symmetry operations on the generators of the groups that define the billiard dynamics, and acquires different features for the different statistical maps. Evidence for scars at the quantum regime is provided. The validity of the Selberg trace formula at the classical level and in the quantum regime enforces the validity of the semiclassical descriptions of these systems, thus offering further elements for the comparison of quantum-gravity effec...
A New Way to Derive the Taub-NUT Metric with Positive Cosmological Constant
Osuga, Kento
2016-01-01
We investigate a biaxial Bianchi IX model with positive cosmological constant, which is sometimes called the Lambda-Taub-NUT spacetime, whose exact solution is well known. The minisuperspace of biaxial Bianchi IX models admits two non-trivial Killing tensors that play an important role for deriving the Taub-NUT metric. We also give a brief discussion about the asymptotic behaviour of Bianchi IX models.
Singularities in Silent Universes State of the Art
Bruni, M; Uggla, C
1996-01-01
After a brief overview of the so-called silent models and their present status, we consider the subclass of Bianchi Type--I models with a magnetic field source. Due to the presence of the magnetic field, the initial singularity shows ``oscillatory'' features reminiscent of the Bianchi Type--IX case. The Bianchi Type--I models with a magnetic field are therefore a counterexample to the folklore that matter fields can be neglected in the vicinity of the singularity.
Symmetries of homogeneous cosmologies
Cotsakis, S; Pantazi, H; Cotsakis, Spiros; Leach, Peter; Pantazi, Hara
1998-01-01
We reformulate the dynamics of homogeneous cosmologies with a scalar field matter source with an arbitrary self-interaction potential in the language of jet bundles and extensions of vector fields. In this framework, the Bianchi-scalar field equations become subsets of the second Bianchi jet bundle, $J^2$, and every Bianchi cosmology is naturally extended to live on a variety of $J^2$. We are interested in the existence and behaviour of extensions of arbitrary Bianchi-Lie and variational vector fields acting on the Bianchi variety and accordingly we classify all such vector fields corresponding to both Bianchi classes $A$ and $B$. We give examples of functions defined on Bianchi jet bundles which are constant along some Bianchi models (first integrals) and use these to find particular solutions in the Bianchi total space. We discuss how our approach could be used to shed new light to questions like isotropization and the nature of singularities of homogeneous cosmologies by examining the behaviour of the vari...
Anisotropic cosmological models and generalized scalar tensor theory
Indian Academy of Sciences (India)
Subenoy Chakraborty; Batul Chandra Santra; Nabajit Chakravarty
2003-10-01
In this paper generalized scalar tensor theory has been considered in the background of anisotropic cosmological models, namely, axially symmetric Bianchi-I, Bianchi-III and Kortowski–Sachs space-time. For bulk viscous ﬂuid, both exponential and power-law solutions have been studied and some assumptions among the physical parameters and solutions have been discussed.
Evaluating the Security of Machine Learning Algorithms
2008-05-20
description of this setting and several results appear in Cesa -Bianchi and Lugosi [2006]. 2.5 Summary In this chapter we have presented a framework for...Learning Research (JMLR), 3:993–1022, 2003. ISSN 1533-7928. Nicolò Cesa -Bianchi and Gábor Lugosi. Prediction, Learning, and Games. Cambridge University
Distributed Algorithms for Learning and Cognitive Medium Access with Logarithmic Regret
2010-06-08
Sadler, “A Survey of Dynamic Spectrum Access,” IEEE Signal Proc. Mag., vol. 24, no. 3, pp. 79–89, 2007. [3] N. Cesa -Bianchi and G. Lugosi, Prediction...1995. [11] P. Auer, N. Cesa -Bianchi, and P. Fischer, “Finite-time Analysis of the Multiarmed Bandit Problem,” Machine Learning, vol. 47, no. 2, pp
Using Pattern Analysis and Systematic Randomness to Allocate U.S. Border Security Resources
2012-01-01
bandit models (see, e.g., Cesa -Bianchi and Lugosi, 2006). A second rationale for introducing systematic randomness is that it makes it harder for...Washington, D.C.: Congressional Research Service, RS21729, November 9, 2006. Cesa -Bianchi, Nicolo, and Gabor Lugosi, Prediction, Learning, and
Density Estimation and Anomaly Detection in Large Social Networks
2014-07-15
Oxford, UK, 1997. 25 BIBLIOGRAPHY [16] N. Cesa -Bianchi, P. Gaillard, G. Lugosi, and G. Stoltz. A new look at shifting regret. arXiv:1202.3323, 2012...17] N. Cesa -Bianchi and G. Lugosi. Prediction, Learning and Games. Cambridge University Press, New York, 2006. [18] W. Clavin. Managing the deluge of
Turning Down the Noise in the Blogosphere
2009-05-01
learning π∗ from repeated user feedback sessions. Like many online algorithms ( Cesa -Bianchi & Lugosi, 2006), our approach updates our estimated π(t...documents and producing summaries. SIGIR. Cesa -Bianchi, N., & Lugosi, G. (2006). Prediction, learning, and games. Cambridge University Press. Chen, H
The Sardinian Literary Spring: An Overview. A New Perspective on Italian Literature
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Michele Broccia
2014-03-01
Full Text Available This article aims at presenting today’s Sardinian literary scene and how some novelists (Sergio Atzeni, Giulio Angioni, Salvatore Mannuzzu, Salvatore Niffoi, Marcello Fois, Giorgio Todde, Milena Agus, Francesco Abate, Flavio Soriga and Michela Murgia, during the last few decades, drawing their narrative subjects directly from the regional and local culture, are contributing to a new development in Italian literature. These authors’ novels often contain references to Sardinian linguistic, social, anthropological and historical facts. Their success has led literary critics to talk about a Sardinian Literary Spring or Sardinian Nouvelle Vague, i.e. a literary phenomenon, which is the expression of a deep-rooted Sardinian identity.
Life Domain Satisfaction: A Portugal-France Comparison
Ruiz Paiva, Maria Fatima; Neto, Felix; Munoz Sastre, Maria Teresa; Laumond-Salvatore, Nadine; Riviere, Sheila; Mullet, Etienne
2009-01-01
The study was aimed at replicating on a Portuguese sample the seven-factor model of life appraisal (physical autonomy, love life, family life, social life, occupational life, finances, and leisure life) that was suggested by Salvatore and Munoz Sastre ["Social Indicators Research" 53:229-255 (2001)]. A sample of 1,111 Portuguese…
Cinema and Pedagogy: An Urban Education Seminar
Meyer, Karen Ann; Vellani, Al-Munir
2014-01-01
In "Cinema Paradiso" (Tomatore, 1988), Salvatore's love of movies came from spending his earlier, young life inside a cinema with the fatherly projectionist Alfredo, now blind and bitter. Alfredo is right. Life is much harder, yes, yet still very much "like in the movies" filled with frustrated actions, performed inside blind…
De la libertad religiosa a la promoción de las religiones
Directory of Open Access Journals (Sweden)
Iván C. Ibán
2011-03-01
Full Text Available Notas utilizadas para mi intervención en la mesa redonda celebrada en la Società Italiana per la Storia Patria, en su sede en Palermo, el día 11 de marzo de 2008, organizada por el profesor Salvatore Bordonali.
77 FR 43900 - Senior Executive Service Performance Review Boards Membership
2012-07-26
...Millan, Therese Watkins Mello, Mary Elizabeth Patrick, Robert C. Rogers, Leslie T. Simon, Marisol R.... Michael, Jeffrey P. Saul, Roger A. Shelton, Terry T. Simons, James F. Smith, Daniel C. Vincent, O. Kevin..., Gregory D. Saint Lawrence Seaway Development Corporation Middlebrook, Craig H. Pisani, Salvatore...
Directory of Open Access Journals (Sweden)
Redazione Reti Medievali (a cura di
2010-12-01
Full Text Available Peer reviewed by Renato Bordone, Filippo Burgarella, Sandro Carocci, Alexandra Chavarria Arnau, Simone Collavini, Salvatore Cosentino, Cristina La Rocca, Lech Leciejewicz, Jean-Claude Maire Vigueur, Marc Mayer, Eduardo Manzano Moreno, Fabio Saggioro, Chris Wickham, Enrico Zanini, Luca Zavagno.
Effects of emotions on optimism bias and illusion of control in traffic.
Mesken, J. Hagenzieker, M.P. & Rothengatter, T.
2005-01-01
Anger is related to aggression in traffic, which in turn may lead to risky driving (e.g. Lajunen, Parker & Stradling, 1998; Deffenbacher, Huff, Lynch, Oetting & Salvatore, 2000; Parker, Lajunen & Summa!a, 2002; Deffenbacher, Lynch, Filetti, Dahlen & Oetting, 2003). Anger may also lead directly to
Uued freskod Pompeist / Maria-Kristiina Soomre
Soomre, Maria-Kristiina, 1978-
2000-01-01
Pompei linnamüürist väljaspool asuvate üle 2000 aasta vanuse luksushotelli varemete väljakaevamisel leiti freskod, mis on maalitud vahetult enne Pompei hävitanud vulkaanipurset. Uurimistööde juht Salvatore Neppo.
Преданья вечной старины / Виталий Андреев ; комментировал Юри Хайн
Андреев, Виталий
2004-01-01
Rahvusraamatukogus avatud näitust "Euroopa 17. sajandi sügavtrükigraafika Eesti Rahvusraamatukogus" kommenteerib kuraator Jüri Hain. Eksponeeritakse vasegravüüre ja oforte. Autorite hulgas on sellised kuulsused nagu Jacques Callot ja Salvatore Rosa
Преданья вечной старины / Виталий Андреев ; комментировал Юри Хайн
Андреев, Виталий
2004-01-01
Rahvusraamatukogus avatud näitust "Euroopa 17. sajandi sügavtrükigraafika Eesti Rahvusraamatukogus" kommenteerib kuraator Jüri Hain. Eksponeeritakse vasegravüüre ja oforte. Autorite hulgas on sellised kuulsused nagu Jacques Callot ja Salvatore Rosa
Cinema and Pedagogy: An Urban Education Seminar
Meyer, Karen Ann; Vellani, Al-Munir
2014-01-01
In "Cinema Paradiso" (Tomatore, 1988), Salvatore's love of movies came from spending his earlier, young life inside a cinema with the fatherly projectionist Alfredo, now blind and bitter. Alfredo is right. Life is much harder, yes, yet still very much "like in the movies" filled with frustrated actions, performed inside blind…
Spin precession in anisotropic cosmologies
Energy Technology Data Exchange (ETDEWEB)
Kamenshchik, A.Yu. [Universita di Bologna, Dipartimento di Fisica e Astronomia, Bologna (Italy); L. D. Landau Institute for Theoretical Physics, Moscow (Russian Federation); INFN, Bologna (Italy); Teryaev, O.V. [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation); Lomonosov Moscow State University, Moscow (Russian Federation)
2016-05-15
We consider the precession of a Dirac particle spin in some anisotropic Bianchi universes. This effect is present already in the Bianchi-I universe. We discuss in some detail the geodesics and the spin precession for both the Kasner and the Heckmann-Schucking solutions. In the Bianchi-IX universe the spin precession acquires the chaotic character due to the stochasticity of the oscillatory approach to the cosmological singularity. The related helicity flip of fermions in the very early universe may produce the sterile particles contributing to dark matter. (orig.)
A Class of Homogeneous Scalar Tensor Cosmologies with a Radiation Fluid
Yazadjiev, Stoytcho S.
We present a new class of exact homogeneous cosmological solutions with a radiation fluid for all scalar tensor theories. The solutions belong to Bianchi type VIh cosmologies. Explicit examples of nonsingular homogeneous scalar tensor cosmologies are also given.
Toward a gauge field theory of gravity.
Yilmaz, H.
Joint use of two differential identities (Bianchi and Freud) permits a gauge field theory of gravity in which the gravitational energy is localizable. The theory is compatible with quantum mechanics and is experimentally viable.
New exact perfect fluid solutions of Einstein's equations. II
Uggla, Claes; Rosquist, Kjell
1990-12-01
A family of new spatially homogeneous Bianchi type VIh perfect fluid solutions of the Einstein equations is presented. The fluid flow is orthogonal to the spatially homogeneous hypersurfaces, and the pressure is proportional to the energy density.
Inflation and Singularity in Einstein-Cartan Theory
Institute of Scientific and Technical Information of China (English)
HUANG Zeng-Guang; FANG Wei; LU Hui-Qing
2011-01-01
@@ Within the framework of Einstein-Cartan theory, we obtain a general condition leading to singularity and inflation for all Bianchi cosmological models.If the spin energy is smaller than anisotropic energy density (i.e.S2 -σ2 -pv/2(pv is vacuum energy density), the Universe can undergo an inflation phase.Examples of Bianchi type-IX, I and V cosmological models are discussed.%Within the framework of Einstein-Cartan theory, we obtain a general condition leading to singularity and inflation for all Bianchi cosmological models. If the spin energy is smaller than anisotropic energy density (i.e. S2-σ2≤ 0),the Universe can not avoid singularity. If S2 -σ2 ＞ -ρv/2 (pv is vacuum energy density), the Universe can undergo an inflation phase. Examples of Bianchi type-Ⅸ, Ⅰ and Ⅴ cosmological models are discussed.
Planck 2015 results: XVIII. Background geometry and topology of the Universe
DEFF Research Database (Denmark)
Ade, P. A R; Aghanim, N.; Arnaud, M.
2016-01-01
1 slab. The limit for the T3 cubic torus from the matched-circles search is numerically equivalent, ℛi > 0.97 χrec at 99% confidence level from polarization data alone. We also perform a Bayesian search for an anisotropic global Bianchi VIIh geometry. In the non-physical setting, where the Bianchi...... cosmology is decoupled from the standard cosmology, Planck temperature data favour the inclusion of a Bianchi component with a Bayes factor of at least 2.3 units of log-evidence. However, the cosmological parameters that generate this pattern are in strong disagreement with those found from CMB anisotropy...... data alone. Fitting the induced polarization pattern for this model to the Planck data requires an amplitude of-0.10 ± 0.04 compared to the value of + 1 if the model were to be correct. In the physically motivated setting, where the Bianchi parameters are coupled and fitted simultaneously...
“Will My Risk Parity Strategy Outperform?”
DEFF Research Database (Denmark)
Asness, Clifford; Frazzini, Andrea; Heje Pedersen, Lasse
2013-01-01
A letter is presented in response to the article "Will My Risk Parity Strategy Outperform?" by Robert Anderson, Stephen Bianchi, and Lisa Goldberg, which appeared in the November/December 2012 issue.......A letter is presented in response to the article "Will My Risk Parity Strategy Outperform?" by Robert Anderson, Stephen Bianchi, and Lisa Goldberg, which appeared in the November/December 2012 issue....
Strange quark matter attached to string cloud in general scalar tensor theory of gravitation
Directory of Open Access Journals (Sweden)
V U M Rao
2014-12-01
Full Text Available Bianchi type-VI0 space time with strange quark matter attached to string cloud in Nordtvedt [1] general scalar tensor theory of gravitation with the help of a special case proposed by Schwinger [2] is obtained. The field equations have been solved by using the anisotropy feature of the universe in the Bianchi type-VI0 space time. Some important features of the model, thus obtained, have been discussed
L’unico ribelle: Il profeta Wraps-up-his-tail e l’identità Crow
Directory of Open Access Journals (Sweden)
Marco Menicocci
2009-06-01
Full Text Available Il 5 novembre 1887 si concluse tragicamente nella riserva dei Crow nel Montana l’unico episodio di rivolta contro i bianchi che abbia interessato questa tribù. Il giovane Wraps-up-his-tail, che aveva cercato di sollevare gli indiani contro i bianchi, venne da un agente della polizia indiana della riserva. La ricostruzione dell'evento può contribuire a gettare luce sul fenomeno del cosiddetto "profetismo" indiano.
New developments in the management of advanced melanoma – role of pembrolizumab
Directory of Open Access Journals (Sweden)
Improta G
2015-09-01
Full Text Available Giuseppina Improta,1 Isabella Leone,1 Marco Donia,2 Stefania Gieri,3 Giuseppe Pelosi,4,5 Filippo Fraggetta6 1Laboratory of Clinical Research and Advanced Diagnostics, IRCCS-CROB, Rionero in Vulture, Potenza, Italy; 2Center for Cancer Immune Therapy, Department of Hematology, Copenhagen University Hospital, Herlev, Denmark; 3Laboratory of Oncologic Technologies, IBFM-CNR, Cefalù, Potenza, 4Department of Pathology and Laboratory Medicine, Fondazione IRCCS Istituto Nazionale Tumori, Milan, 5Department of Biomedical and Clinical Sciences “Luigi Sacco”, Università degli Studi di Milano, Milan, 6Department of Pathology, Cannizzaro Hospital, Catania, Italy Abstract: Cancer immunotherapy is now recognized to be fundamental in modern oncology, because immune system recruitment may represent a powerful and innovative strategy in cancer therapy. Pembrolizumab, a highly selective humanized monoclonal antibody directly blocking the interaction between programmed cell death-1 expressed by tumor-associated T-cells and its ligand programmed cell death-L1 present on tumor and stromal cells, was recently approved by US Food and Drug Administration for the treatment of patients with unresectable or metastatic melanoma and disease progression upon ipilimumab and BRAF inhibitor. This review will focus on the clinical development and use of pembrolizumab in the clinical practice and in the management of advanced melanoma. Keywords: advanced melanoma, immunotherapy, PD-1 inhibitor, pembrolizumab
Development of a Barthel Index based on dyspnea for patients with respiratory diseases
Directory of Open Access Journals (Sweden)
Vitacca M
2016-06-01
Full Text Available Michele Vitacca,1 Mara Paneroni,1 Paola Baiardi,2 Vito De Carolis,3 Elisabetta Zampogna,4 Stefano Belli,5 Mauro Carone,3 Antonio Spanevello,4,6 Bruno Balbi,5 Giorgio Bertolotti7 1Respiratory Rehabilitation Division, Salvatore Maugeri Foundation, IRCCS, Institute of Lumezzane, Brescia, 2Scientific Direction, Salvatore Maugeri Foundation, IRCCS, Institute of Pavia, Pavia, 3Respiratory Division, Salvatore Maugeri Foundation, IRCCS, Institute of Cassano delle Murge, Bari, 4Respiratory Division, Salvatore Maugeri Foundation, IRCCS, Institute of Tradate, Varese, 5Respiratory Division, Salvatore Maugeri Foundation, IRCCS, Institute of Veruno, Novara, 6Respiratory Diseases Unit, University of Insubria, Varese, 7Psychology Unit, Salvatore Maugeri Foundation, IRCCS, Institute of Tradate, Varese, Italy Background: As Barthel Index (BI quantifies motor impairment but not breathlessness, the use of only this index could underestimate disability in chronic respiratory disease (CRD. To our knowledge, no study evaluates both motor and respiratory disability in CRD during activities of daily living (ADLs simultaneously and with a unique tool. The objective of this study was to propose for patients with CRD an additional tool for dyspnea assessment during ADLs based on BI items named Barthel Index dyspnea.Methods: Comprehensibility, reliability, internal consistency, validity, responsiveness, and ability to differentiate between disease groups were assessed on 219 subjects through an observational study performed in an in-hospital rehabilitation setting.Results: Good comprehensibility, high reliability (interrater intraclass correlation coefficient was 0.93 [95% confidence interval 0.892–0.964] and test–retest intraclass correlation coefficient was 0.99 [95% confidence interval 0.983–0.994], good internal consistency (Cronbach’s alpha 0.89, strong concurrent validity with 6 minute walking distance (Pearson r=–0.538, P<0.001 and Medical Research Council
De Luca Picione, Raffaele
2015-09-01
In this paper I discuss the relevance of the single-case approach in psychological research. Based upon work by Hurtado-Parrado and López-López (Integrative Psychological and Behavioral Science, 2015), who outlined the possibility that Single-Case Methods (SCMs) could be a valid alternative to Null Hypothesis Significance Testing (NHST), I introduce the idiographic approach (Salvatore and Valsiner Theory & Psychology, 20(6), 817-833, 2010; Valsiner Cultural & Psychology, 20(2), 147-159, 2014; Salvatore Culture & Psychology, 20(4), 477-500, 2014) based on the logic of abductive generalization, rather than the logic of inductive generalization. I present the theoretical, epistemological and methodological assumptions that this approach proposes; in particular, I discuss the re-conceptualization of some now obsolete rigid opposition, the inconsistency of sample use in psychological research, the relationship between uniqueness and general, the relationship between theory and phenomena, and finally the validation process.
What sense can the sense-making perspective make for economics?
Cortés, Mauricio; Londoño, Sandra
2009-06-01
A landscape of interdisciplinary decision theories is sketched with a tentative place for the sense-making approach presented by Salvatore et al (2009). Uncertainty and ambiguity are highlighted as key concepts in both, economics and sense-making perspectives aligning possible and useful conceptual coincidences among post Keynesian economics (Shackle 1974; Davidson 2005) cultural psychology (Salvatore et al. 2009) and organization theory (March 1978, 1994; Weick 1995). Few ideas for the construction of possible research agenda aimed to build a complex model of decision making are suggested. Finally a brief reflection on the study of underground economy is presented. The challenge for the link between psychology and economics is to figure out a descriptive general model of the process of decision making, perhaps by combining weighted elements of the different ways in which human rationality emerges--calculation, rule following, sense-making--for explaining singular and specific decisions.
Uudiseid maailmast / Nele-Eva Steinfeld
Steinfeld, Nele-Eva
2012-01-01
Lühisõnumid: Londoni BBC sümfooniaorkestri peadirigendiks saab Sakari Oramo. Preemia Salvatore Sciarrinole. Maurice Andre (1933-2012). Elisabeth Connell (1947-2012). Uued teosed Mozartilt ja Elgarilt. Emerson Quartet muudab koosseisu. Tunnustus Paavo Järvile. Seiji Ozawa võtab aastase puhkuse. Metropolitan Opera uus piletimüügistrateegia. Van Cliburni antiigikogu oksjonil. Vabaõhukontserdid Trafalgari väljakul jne.
Anales de Literatura Española
1986-01-01
Contiene: Un filosofo alla corte di Bisancio : MICHELE PSELLO Imperatori di Bisanzio (Cronografia). Introduzione di Dario Del Corno, testo critico a cura di Salvatore Impellizzeri, commento di Ugo Criscuolo, traduzione di Silvia Ronchey. Fondazione Lorenzo Valla-Mondadori, Milano, 1984, 2 vol. / STEFANO ARDUINI ; Una edición de Antonio de Guevara : ANTONIO DE GUEVARA Menosprecio de corte y alabanza de aldea. Arte de marear. Edición de Asunción Rallo. Madrid, C...
The installation teams for the LHCb electromagnetic calorimeter and the LHCb hadron calorimeter
Maximilien Brice
2005-01-01
Photo 01 : The installation team for the electromagnetic calorimeter. Top, from left to right, Serge Deckert, Robert Kristic, Bernard Chadaj, and below, Salvatore Lampis, Tengiz Kvaratskheliya, Alexandre Aref'Ev, Bruno Lieunard, Jerôme Dech, Christophe Mazeau, Cedric Fournier Photo 03 : The assembly team for the hadron calorimeter: from top to bottom, Rustem Dzhelyadin, Robert Kristic, Patrick Vallet, then left to right Vitaly Polyakov, Evgeny Chernov and Kirill Kachnov, and lastly Frank Lamour.
Modélisation aléatoire de l'activité des Lymphocytes T Cytotoxyques
Christophe, Claire
2014-01-01
This thesis studies some statistical and probability properties of the dynamic of Cytotoxic T Lymphocyte(CTL, immune cells) and a tumor nodule. This work is in close collaboration with SalvatoreValitutti team at INSERM. Considering the complexity of developing an in vitro tumor nodule, wedevelop an agent based model to describe and understand the interaction between CTL and tumor.Numerical experiments highlight two important parameters in CTL immune response against tumormass. Primarily the C...
D’Hondt F; Campanella S; Kornreich C; Philippot P; Maurage P
2014-01-01
Fabien D’Hondt,1 Salvatore Campanella,2 Charles Kornreich,2 Pierre Philippot,1 Pierre Maurage1 1Laboratory for Experimental Psychopathology, Psychological Sciences Research Institute, Université Catholique de Louvain, Louvain-la-Neuve, Belgium; 2Laboratory of Medical Psychology and Addictology, ULB Neuroscience Institute (UNI), Université Libre de Bruxelles, Brussels, Belgium Abstract: Studies that have carried out experimental evaluation of emotional skills ...
Rescue Assault Forces--Integrated Strategic Role in National Security
1982-06-04
24 Salvatore Pizzarro, "Mexico’s Oil Boom," Current Histo,. 80, No. 463 (1981), 49. Petroleos Mexicanos (Pemex) indicates stocks of 60 to 100 billion...1981. DOD (Public Affairs) News Release Ho. 328-81, p. 2. 40p. Cit., Haig, 4. 5Robert Leider, *An Old Strategist Speaks to the Young,’ Military...the survival of the Western world through economic destruction of industry. 75 7- ’V 18 Robert Leider, "An Old Strategist Speaks to the Young
Yuan Li; Burns, Janine A.; Carol A Cheney; et al
2010-01-01
Yuan Li1, Janine A Burns1, Carol A Cheney1, Ningyan Zhang1, Salvatore Vitelli1, Fubao Wang1, Andrew Bett2, Michael Chastain2, Laurent P Audoly1, Zhi-Qiang Zhang1,31Department of Biologics Research, 2Department of Vaccine Research, Merck Research Laboratories, West Point, PA, USA; 3Clinical Development Laboratory, Merck Research Laboratories, Rahway, NJ, USAAbstract: Biological therapies, such as monoclonal antibodies (mAbs) that target tumor-associated antigens have been considered an effecti...
Luxury Fashion: An Integral Part of The Indian Society
Sachdeva, Anshu
2009-01-01
Abstract Today’s brand conscious Indian man drives a Porsche Cayenne SUV, wears Ermenegildo Zegna suits, his wrist is adorned with a Patek Philippe watch, his eyewear are of Prada, and his shoes of Salvatore Ferragamo, his brief case from Mont Blanc and his mobile phone of Vertu. The fashion conscious Indian woman of today, carries off outfits from Stella McCartney, bags of Louis Vuitton, jewellery of Bvlgari, Cartier, etc and wears a priceless attitude, ending up looking absolutely drop ...
Clinical utility of lanreotide autogel® in gastroenteropancreatic neuroendocrine tumors
Paragliola RM; Prete A; Papi G; Torino F; Corsello A; Pontecorvi A; Corsello SM
2016-01-01
Rosa Maria Paragliola,1 Alessandro Prete,1 Giampaolo Papi,1 Francesco Torino,2 Andrea Corsello,3 Alfredo Pontecorvi,1 Salvatore Maria Corsello1 1Department of Medicine, Unit of Endocrinology, Università Cattolica del Sacro Cuore, 2Department of Systems Medicine, Tor Vergata University, Rome, 3Department of General Medicine and Endocrine Tumor Unit, San Raffaele Scientific Institute, Milan, Italy Abstract: Somatostatin analogs (SSAs), which were initially used to control hormonal ...
Gareri P; Castagna A; Cotroneo AM; Putignano S; De Sarro G; Bruni AC
2015-01-01
Pietro Gareri,1 Alberto Castagna,1 Antonino Maria Cotroneo,2 Salvatore Putignano,3 Giovambattista De Sarro,4 Amalia Cecilia Bruni11Centro Regionale di Neurogenetica, ASP Catanzaro, Lamezia Terme, Catanzaro, 2ASL2 Turin, Turin, 3Elderly Assistance Unit, Naples, 4Department of Health Sciences, School of Medicine, University Magna Græcia of Catanzaro, Catanzaro, ItalyBackground: Citicoline is able to potentiate neuroplasticity and is a natural precursor of phospholipi...
A Complex Adaptive Systems Approach to the Future Operational Environment
2014-05-22
structuralism and functionalism.23 Sigmund Freud merged these fields with a mix of science and interpretation. His psychoanalysis principle introduced the...the conscious and unconscious are established at an early age. With the rise of experimental processes, behaviorists pushed Freud out of from primacy...University Press, 2006). 24For an in-depth comparison of various personality theories and Sigmund Freud in particular see Salvatore R. Maddi, Personality
Human Capital Analytics to Manage the Army Officer Population
2017-06-09
Competing on Talent Analytics.” Harvard Business Review (October): 54-58. Davenport, Thomas H. 2013. .Enterprise Analytics. Upper Saddle River, NJ: Pearson...Society for Human Resource Management. Boudreau, John W., and Peter M. Ramstad. 2007. Beyond HR. Boston, MA: Harvard Business School Press. Boudreau...Education. Davenport, Thomas, Jeanne Harris, and Robert Morison. 2010. .Analytics at Work. Boston: Harvard Business Press. Falletta, Salvatore
Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
Singh, Parampreet
2013-01-01
We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed Friedmann-Lemaitre-Robertson-Walker cosmology, we find that using open holonomies of the extrinsic curvature, which due to gauge-fixing can be treated as a connection, leads to the same quantum geometry effects that are found in spatially flat cosmologies. More specifically, in contrast to the quantization based on open holonomies of the Ashtekar-Barbero connection, the expansion and shear scalars in the effective theories of the Bianchi type II and Bianchi type IX models have upper bounds, and these are in exact agreement with the bounds found in the effective theories of the Friedmann-Lemaitre-Robertson-Walker and Bianchi type I models in loop quantum cosmology. We also comment on some ambiguities present in the definition of inverse triad operators and their role.
The tensor hierarchy of 8-dimensional field theories
Andino, Óscar Lasso; Ortín, Tomás
2016-10-01
We construct the tensor hierarchy of generic, bosonic, 8-dimensional field theories. We first study the form of the most general 8-dimensional bosonic theory with Abelian gauge symmetries only and no massive deformations. This study determines the tensors that occur in the Chern-Simons terms of the (electric and magnetic) field strengths and the action for the electric fields, which we determine. Having constructed the most general Abelian theory we study the most general gaugings of its global symmetries and the possible massive deformations using the embedding tensor formalism, constructing the complete tensor hierarchy using the Bianchi identities. We find the explicit form of all the field strengths of the gauged theory up to the 6-forms. Finally, we find the equations of motion comparing the Noether identities with the identities satisfied by the Bianchi identities themselves. We find that some equations of motion are not simply the Bianchi identities of the dual fields, but combinations of them.
The tensor hierarchy of 8-dimensional field theories
Andino, Oscar Lasso
2016-01-01
We construct the tensor hierarchy of generic, bosonic, 8-dimensional field theories. We first study the form of the most general 8-dimensional bosonic theory with Abelian gauge symmetries only and no massive deformations. This study determines the tensors that occur in the Chern-Simons terms of the (electric and magnetic) field strengths and the action for the electric fields, which we determine. Having constructed the most general Abelian theory we study the most general gaugings of its global symmetries and the possible massive deformations using the embedding tensor formalism, constructing the complete tensor hierarchy using the Bianchi identities. We find the explicit form of all the field strengths of the gauged theory up to the 6-forms. Finally, we find the equations of motion comparing the Noether identities with the identities satisfied by the Bianchi identities themselves. We find that some equations of motion are not simply the Bianchi identities of the dual fields, but combinations of them.
Cosmic no hair for collapsing universes
Energy Technology Data Exchange (ETDEWEB)
Lidsey, James E [Astronomy Unit, School of Mathematical Sciences Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)
2006-05-21
It is shown that all contracting, spatially homogeneous, orthogonal Bianchi cosmologies that are sourced by an ultra-stiff fluid with an arbitrary and, in general, varying equation of state asymptote to the spatially flat and isotropic universe in the neighbourhood of the big crunch singularity. This result is employed to investigate the asymptotic dynamics of a collapsing Bianchi type IX universe sourced by a scalar field rolling down a steep, negative exponential potential. A toroidally compactified version of M*-theory that leads to such a potential is discussed and it is shown that the isotropic attractor solution for a collapsing Bianchi type IX universe is supersymmetric when interpreted in an 11-dimensional context.
Affine Coherent States in Quantum Cosmology
Malkiewicz, Przemyslaw
2015-01-01
A brief summary of the application of coherent states in the examination of quantum dynamics of cosmological models is given. We discuss quantization maps, phase space probability distributions and semiclassical phase spaces. The implementation of coherent states based on the affine group resolves the hardest singularities, renders self-adjoint Hamiltonians without boundary conditions and provides a completely consistent semi-classical description of the involved quantum dynamics. We consider three examples: the closed Friedmann model, the anisotropic Bianchi Type I model and the deep quantum domain of the Bianchi Type IX model.
General relativity as the equation of state of spin foam
Smolin, Lee
2012-01-01
Building on recent significant results of Frodden, Ghosh and Perez (FGP) and Bianchi, I present a quantum version of Jacobson's argument that the Einstein equations emerge as the equation of state of a quantum gravitational system. I give three criteria a quantum theory of gravity must satisfy if it is to allow Jacobson's argument to be run. I then show that the results of FGP and Bianchi provide evidence that loop quantum gravity satisfies two of these criteria and argue that the third should also be satisfied in loop quantum gravity. I also show that the energy defined by FGP is the canonical energy associated with the boundary term of the Holst action.
Exact anisotropic viscous fluid solutions of Einstein's equations
Goenner, H. F. M.; Kowalewski, F.
1989-05-01
A method for obtaining anisotropic, rotationless viscous fluid matter solutions of Bianchi type I and Segré type [1, 111] with the barotropic equation of state is presented. Solutions for which the anisotropy decreases exponentially or with a power law as well as solutions with average Hubble parameterH ˜t -1 are discussed. Also, a class of solutions with constant anisotropy and Bianchi type VIh is found. The dominant energy condition holds and the transport coefficients show the right sign.
Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza
1999-04-01
Global symmetries of the string effective action are employed to generate tilted, homogeneous Bianchi type VIh string cosmologies from a previously known stiff perfect fluid solution to Einstein gravity. The dilaton field is not constant on the surfaces of homogeneity. The future asymptotic state of the models is interpreted as a plane wave and is itself an exact solution to the string equations of motion to all orders in the inverse string tension. An inhomogeneous generalization of the Bianchi type III model is also found.
Modelos cosmológicos anisótropos con constantes variables: un enfoque autosimilar
2012-01-01
El objetivo de esta Tesis es estudiar la variación de las constantes físicas universales y con respecto al tiempo cosmológico, en modelos homogéneos pero anisótropos, es decir, los denominados modelos de Bianchi, junto con el modelo Kantowski-Sachs. Estudiaremos dicha variación dentro del marco teórico de varias teorías gravitatorias, como son: •Relatividad General (RG), convenientemente modificada en base a la identidad de Bianchi •Modelos quintaesencia (SM), considerando además los casos en...
Unitary evolution for anisotropic quantum cosmologies: models with variable spatial curvature
Pandey, Sachin
2016-01-01
Contrary to the general belief, there has recently been quite a few examples of unitary evolution of quantum cosmological models. The present work gives more examples, namely Bianchi type VI and type II. These examples are important as they involve varying spatial curvature unlike the most talked about homogeneous but anisotropic cosmological models like Bianchi I, V and IX. We exhibit either explicit example of the unitary solutions of the Wheeler-DeWitt equation, or at least show that a self-adjoint extension is possible.
Unitary evolution for anisotropic quantum cosmologies: models with variable spatial curvature
Pandey, Sachin; Banerjee, Narayan
2016-11-01
Contrary to the general belief, there has recently been quite a few examples of unitary evolution of quantum cosmological models. The present work gives more examples, namely Bianchi type VI and type II. These examples are important as they involve varying spatial curvature unlike the most talked about homogeneous but anisotropic cosmological models like Bianchi I, V and IX. We exhibit either an explicit example of the unitary solutions of the Wheeler-DeWitt equation, or at least show that a self-adjoint extension is possible.
Local spinfoam expansion in loop quantum cosmology
Henderson, Adam; Vidotto, Francesca; Wilson-Ewing, Edward
2010-01-01
The quantum dynamics of the flat Friedmann-Lemaitre-Robertson-Walker and Bianchi I models defined by loop quantum cosmology have recently been translated into a spinfoam-like formalism. The construction is facilitated by the presence of a massless scalar field which is used as an internal clock. The implicit integration over the matter variable leads to a nonlocal spinfoam amplitude. In this paper we consider a vacuum Bianchi I universe and show that by choosing an appropriate regulator a spinfoam expansion can be obtained without selecting a clock variable and that the resulting spinfoam amplitude is local.
Magnetic monopoles and relativistic cosmological models
Energy Technology Data Exchange (ETDEWEB)
Stein-Schabes, J.A.
1984-01-01
A dissertation is presented on magnetic monopoles and relativistic cosmological models. The maximum number density of monopoles in various astrophysical scenarios was investigated along with: the monopole flux in the galaxy, the allowed monopole abundance, and the formation of stable monopole orbits. Limits on the mass and lifetime of monopolonium were calculated. Boltzmann's equation was used to calculate the monopole abundance in a magnetic axisymmetric Bianchi I cosmological model, and a solution was found describing an axisymmetric Bianchi I magnetic cosmology with monopoles. New inhomogeneous solutions to Einstein's equations were found. Finally, stability and inflation in Kaluza-Klein cosmologies in d + D + 1 dimensions was studied.
Inflation in a renormalizable cosmological model and the cosmic no-hair conjecture
Energy Technology Data Exchange (ETDEWEB)
Maeda, K.; Stein-Schabes, J. A.; Futamase, T.
1989-05-15
The possibility of having inflation in a renormalizable cosmological model is investigated. The cosmic no-hair conjecture is proved to hold for all Bianchi types except Bianchi type IX. By the use of a conformal transformation on the metric we show that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, we prove that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.
Inflation in a renormalizable cosmological model and the cosmic no hair conjecture
Maeda, Kei-Ichi; Stein-Schabes, Jaime A.; Futamase, Toshifumi
1988-01-01
The possibility of having inflation in a renormalizable cosmological model is investigated. The Cosmic No Hair Conjecture is proved to hold for all Bianchi types except Bianchi IX. By the use of a conformal transformation on the metric it is shown that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, it is proven that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.
Directory of Open Access Journals (Sweden)
Musto P
2014-06-01
Full Text Available Pellegrino Musto,1 Vittorio Simeon,2 Roberto Guariglia,3 Gabriella Bianchino,4 Vitina Grieco,4 Filomena Nozza,4 Francesco La Rocca,2 Gioacchino Marziano,1 Anna Vittoria Lalinga,5 Emiliano Fabiani,6 Maria Teresa Voso,6 Patrizia Scaravaglio,7 Cristina Mecucci,8 Giovanni D'Arena31Scientific Direction, 2Laboratory of Preclinical and Translational Research, 3Unit of Hematology and Stem Cell Transplantation, 4Laboratory of Clinical Research and Advanced Diagnostics, 5Pathology Unit, IRCCS, Centro di Riferimento Oncologico della Basilicata, Rionero in Vulture, Italy; 6Department of Hematology, Universita Cattolica del Sacro Cuore, Rome, Italy; 7Laboratory of Internal Medicine and Hematology, S Luigi Gonzaga Hospital, Orbassano, Italy; 8Hematology and Bone Marrow Transplantation Unit, University of Perugia, Perugia, ItalyAbstract: The concomitant presence of del(5q and JAK2V617F mutation is an infrequent event which occurs in rare patients with peculiar cytogenetic, molecular, morphological and clinical features, resembling those of both myelodysplastic syndromes and myeloproliferative neoplasms. Lenalidomide may induce rapid, profound, and long-lasting responses in a subset of these patients. However, the mechanism(s by which the drug acts in these conditions remain not completely elucidated. A new case report and a review of all cases published so far in this setting are provided. Furthermore, the possibility of categorizing – from a clinical, pathological, and biological point of view – for at least some of these patients as a potential distinct entity is discussed.Keywords: myelodysplastic syndromes, myeloproliferative neoplasms, lenalidomide, del(5q, JAK2, World Health Organization
Lipegfilgrastim in the management of chemotherapy-induced neutropenia of cancer patients
Directory of Open Access Journals (Sweden)
Guariglia R
2016-01-01
Full Text Available Roberto Guariglia,1 Maria Carmen Martorelli,1 Rosa Lerose,2 Donatella Telesca,2 Maria Rita Milella,2 Pellegrino Musto3 1Unit of Hematology and Stem Cell Transplantation, 2Pharmacy Service, 3Scientific Direction, IRCCS, Referral Cancer Center of Basilicata, Rionero in Vulture, Potenza, Italy Abstract: Neutropenia and febrile neutropenia (FN are frequent and potentially fatal toxicities of myelosuppressive anticancer treatments. The introduction of granulocyte colony-stimulating factors (G-CSFs in clinical practice has remarkably reduced the duration and severity of neutropenia, as well as the incidence of FN, thus allowing the administration of chemotherapeutic agents at the optimal dose and time with lower risk. The current scenario of G-CSFs in Europe includes filgrastim, lenograstim, some G-CSF biosimilars, and pegfilgrastim. Recently, a novel long-acting G-CSF, lipegfilgrastim, became available. Lipegfilgrastim is a glycopegylated G-CSF, alternative to pegfilgrastim, and has shown in randomized trials, to be equivalent to pegfilgrastim in reducing the incidence of severe neutropenia and FN in patients with breast cancer receiving chemotherapy, with a similar safety profile. Furthermore, lipegfilgrastim was more effective than the placebo in reducing the incidence of severe neutropenia, its duration, and time to absolute neutrophil count recovery, in patients with non-small cell lung cancer receiving myelosuppressive therapy. Although the number of studies currently published is still limited, lipegfilgrastim seems to be a promising drug in the management of chemotherapy-induced neutropenia. Keywords: neutropenia, febrile neutropenia, granulocyte colony-stimulating factors, G-CSF, pegfilgrastim, lipegfilgrastim
New Models for Initial Teacher Education in Scotland
Kibble, Bob
2012-01-01
In this article, the author responds to the recent article by Lynne Bianchi commenting on the Donaldson report, "Teaching Scotland's future" (Donaldson, 2011). He agrees that the Donaldson report has indeed been a catalyst to drive change across the entire landscape of initial teacher education (ITE) in Scotland. In fact, not only ITE: the report…
Noutchegueme, N; Noutchegueme, Norbert; Tetsadjio, Mesmin Erick
2003-01-01
We prove, for the relativistic Boltzmann equation in the homogeneous case, on the Minkowski space-time, a global in time existence and uniqueness theorem. The method we develop extends to the cases of some curved space-times such as the flat Robertson-Walker space-time and some Bianchi type I space-times.
Anisotropic cosmological models in $f (R, T)$ theory of gravitation
Indian Academy of Sciences (India)
Shri Ram; Priyanka; Manish Kumar Singh
2013-07-01
A class of non-singular bouncing cosmological models of a general class of Bianchi models filled with perfect fluid in the framework of $f (R, T)$ gravity is presented. The model initially accelerates for a certain period of time and decelerates thereafter. The physical behaviour of the model is also studied.
Interpretation of the triad orientations in loop quantum cosmology
Kiefer, Claus
2012-01-01
Loop quantum cosmology allows for arbitrary superpositions of the triad variable. We show here how these superpositions can become indistinguishable from a classical mixture by the interaction with fermions. We calculate the reduced density matrix for a locally rotationally symmetric Bianchi I model and show that the purity factor for the triads decreases by decoherence. In this way, the Universe assumes a definite orientation.
2007-11-02
where the PCI slipped up badly. The Lombard delegate Elio Quercioli feels it was a gross psychological error to nominate the Honorable Romana Bianchi...London for 9 years, and under the terms of the statutes only those professing the Mos- lem religion who reside in Portugal can be active mem- bers
Entering adulthood in a recession tempers later narcissism - But only in men
Leckelt, Marius; Back, Mitja D.; Foster, Joshua D.; Hutteman, Roos; Jaeger, Garrett; McCain, Jessica; Twenge, Jean M.; Campbell, W. Keith
2016-01-01
In a recent study, Bianchi (2014) showed that macroeconomic conditions (i.e. average unemployment rate) during the years of emerging adulthood (ages 18-25) are inversely related to adult narcissism. Fletcher (2015) called into question the robustness of the results and Grijalva et al. (2015) present
Hyperbolicity of the 3+1 system of Einstein equations
Energy Technology Data Exchange (ETDEWEB)
Choquet-Bruhat, Y. (I.M.T.A., Paris (France)); Ruggeri, T. (Istituto di Matematica Applicata, Bologna (Italy))
1982-03-22
We obtain a hyperbolic system from the usual evolution equations of the 3+1 treatment by combining appropriately, these equations with the constraints. We obtain from these hyperbolic equations (using also the constraints and Bianchi identities) the existence theorem, in its most refined form.
Supersymmetric compactifications of heterotic strings with fluxes and condensates
Energy Technology Data Exchange (ETDEWEB)
Manousselis, Pantelis [Department of Engineering Sciences, University of Patras, GR-26110 Patras (Greece)]. E-mail: pantelis@upatras.gr; Prezas, Nikolaos [Institut de Physique, Universite de Neuchatel, CH-2000 Neuchatel (Switzerland)]. E-mail: nikolaos.prezas@unine.ch; Zoupanos, George [Physics Department, National Technical University of Athens, GR-15780 University Campus, Athens (Greece)]. E-mail: zoupanos@mail.cern.ch
2006-04-03
We discuss supersymmetric compactifications of heterotic strings in the presence of H-flux and general condensates using the formalism of G-structures and intrinsic torsion. We revisit the examples based on nearly-Kaehler coset spaces and show that supersymmetric solutions, where the Bianchi identity is satisfied, can be obtained when both gaugino and dilatino condensates are present.
Anisotropic Four-Dimensional NS-NS String Cosmology
Chen, C M; Mak, M K; Chen, Chiang-Mei
2001-01-01
An anisotropic (Bianchi type I) cosmology is considered in the four-dimensional NS-NS sector of low-energy effective string theory coupled to a dilaton and an axion-like $H$-field within a de Sitter-Einstein frame background. The time evolution of this Universe is discussed in both the Einstein and string frames.
Homogeneous cosmology dynamics revealed by Hamiltonian ADM formalism
Fay, S
2005-01-01
We study the homogeneous but anisotropic cosmological models of Bianchi in presence of a massive scalar field using the ADM Hamiltonian formalism. We begin to describe the main steps to find the ADM Hamiltonian of the General Relativity with a massive scalar field and then we study the dynamics of the flat Bianchi type $I$ anisotropic Universe according to initial and final values of this Hamiltonian and sign of the potential. After a brief recall of the conditions necessary to isotropise an anisotropic Bianchi class A model with such a field, we extend them to a non minimally coupled scalar field by using a conformal transformation of the metric which casts the General Relativity with a scalar field into a scalar-tensor theory. The new line element then corresponds to the so-called Brans-Dicke frame, the former one being the Einstein frame. Then, we study the isotropisation process of the Bianchi class A model when we consider the low energy form of the string theory without its antisymmetric tensor and the ...
One vertex spin-foams with the Dipole Cosmology boundary
Kisielowski, Marcin; Puchta, Jacek
2012-01-01
We find all the spin-foams contributing in the first order of the vertex expansion to the transition amplitude of the Bianchi-Rovelli-Vidotto Dipole Cosmology model. Our algorithm is general and provides spin-foams of arbitrarily given, fixed: boundary and, respectively, a number of internal vertices. We use the recently introduced Operator Spin-Network Diagrams framework.
Constant Angle Surfaces in the Heisenberg Group
Institute of Scientific and Technical Information of China (English)
Johan FASTENAKELS; Marian Ioan MUNTEANU; Joeri VAN DER VEKEN
2011-01-01
In this article we extend the notion of constant angle surfaces in S2 × R and H2 × R to general Bianchi-Cartan-Vranceanu spaces. We show that these surfaces have constant Gaussian curvature and we give a complete local classification in the Heisenberg group.
Kakskümmend üheksa / Juhapekka Tukiainen
Tukiainen, Juhapekka
2013-01-01
TMi test: 29tollised maastikurattad, hinnaklass 1500 eurot. Bianchi Jab 29.2; Canyon Grand Canyon 8.9 AL 29; Corratec Superbow Team 29; Cube LTD SL 29; Felt Nine 30; Kona Kahuna DL; KTM Ultra Race 29; Merida Big Nine TFS XT Edition
The Torsion of Spinor Connections and Related Structures
Directory of Open Access Journals (Sweden)
Frank Klinker
2006-11-01
Full Text Available In this text we introduce the torsion of spinor connections. In terms of the torsion we give conditions on a spinor connection to produce Killing vector fields. We relate the Bianchi type identities for the torsion of spinor connections with Jacobi identities for vector fields on supermanifolds. Furthermore, we discuss applications of this notion of torsion.
Anisotropic cosmology in S\\'aez-Ballester theory: classical and quantum solutions
Socorro, J; G., M A Sánchez; Palos, M G Frías
2010-01-01
We use the S\\'aez-Ballester theory on anisotropic Bianchi I cosmological model, with barotropic fluid and cosmological constant. We obtain the classical solution by using the Hamilton-Jacobi approach. Also the quantum regime is constructed and exact solutions to the Wheeler-DeWitt equation are found.
1980-01-01
The Radiobiology Group carries out experiments to study the effect of radiation on living cells. The photo shows the apparatus for growing broad beans which have been irradiated by 250 GeV protons. The roots are immersed in a tank of running water (CERN Weekly Bulletin 26 January 1981 and Annual Report 1980 p. 160). Karen Panman, Marilena Streit-Bianchi, Roger Paris.
Rajpoot, Subhash
2016-01-01
Applying the anholonomic frame deformation method, we construct various classes of cosmological solutions for effective Einstein -- Yang-Mills -- Higgs, and two measure theories. The types of models considered are Freedman-Lema\\^{i}tre-Robertson-Walker, Bianchi, Kasner and models with attractor configurations. The various regimes pertaining to plateau--type inflation, quadratic inflation, Starobinsky type and Higgs type inflation are presented.
Collineations of the curvature tensor in general relativity
Indian Academy of Sciences (India)
Rishi Kumar Tiwari
2005-07-01
Curvature collineations for the curvature tensor, constructed from a fundamental Bianchi Type-V metric, are studied. We are concerned with a symmetry property of space-time which is called curvature collineation, and we briefly discuss the physical and kinematical properties of the models.
On the Energy-Momentum in Closed Universes
Salti, M
2006-01-01
Using the Moller, Einstein, Bergmann-Thomson and Landau-Lifshitz energy-momentum definitions both in general relativity and teleparallel gravity, we find the energy-momentum of the closed universe based on the generalized Bianchi-type I metric.
Exact Solutions of the Photon Equation in Anisotropic Spacetimes
Havare, A; Aydogdu, O; Salti, M; Yetkin, T; Havare, Ali; Korunur, Murat; Aydogdu, Oktay; Salti, Mustafa; Yetkin, Taylan
2005-01-01
In this paper we study solution of the photon equation (the Massless Duffin-Kemmer-Petiau equation (mDKP)) in anisotropic expanding the Bianchi-I type spacetime using the Fourier analyze method. The harmonic oscillator behavior of the solutions is found. It is shown that Maxwell equations are equivalent to the photon equation.
A characterization for the sensitivity of a metric
Molaei, Mohammadreza; Khajoei, Najmeh
2016-08-01
In this paper we introduce the universal functions which describe the sensitivity of metrics on the local charts of their ambient manifolds. We find these functions for Bianchi type II, V, VII and IX cosmological models. We also find these values for Kaluza-Klein and FRW space-times.
General relativistic aspects of ferromagneto-fluid
Energy Technology Data Exchange (ETDEWEB)
Asgekar, G.G.; Patwardhan, C.G.
1988-03-01
The implications of Bianchi identities pertaining to the spacetime of relativistic ferrofluid with infinite conductivity and variable magnetic permeability are investigated. Some kinematical and dynamical corollaries emerging out of a preferred geometrical symmetry called an isometry with respect to the flow vector and the magnetic field vector are developed.
General relativistic aspects of ferromagneto-fluid.
Asgekar, G. G.; Patwardhan, C. G.
1988-03-01
The implications of Bianchi identities pertaining to the spacetime of relativistic ferrofluid with infinite conductivity and variable magnetic permeability are investigated. Some kinematical and dynamical corollaries emerging out of a preferred geometrical symmetry called an isometry with respect to the flow vector and the magnetic field vector are developed.
Families as Decision-Makers: When Researchers and Advocates Work Together
Fields-Smith, Cheryl; Neuharth-Pritchett, Stacey
2009-01-01
Families across the United States must routinely make difficult choices about child care arrangements because of the need to resume a job, continue an education or training program, or care for other family members. Leaving children in the care of others for the first time can be difficult (Sayer, Bianchi, & Robinson, 2004; Van Horn, Ramey,…
Wunsch, M; Pompino, H J
1991-01-01
Report about a rare complication of gastroschisis by early volvalus. Following this occasionally the prenatal diagnosis there was a very ultrasonogram of a mostly solid tumour before the abdominal wall. The postpartal operative therapy with resection and later doubling according to Bianchi B described.
2007-11-02
UM21 BACKPACK SYSTEM BIANCHI INTERNATIONAL & GREGORY MOUNTAIN PRODUCTS Report Documentation Page Report Date 13Aug2001...Command. z A modified commercial backpack system y Back Pack y Patrol Pack y Butt Pack Introduction Cont’d z Advanced design and superior technology y
Superspace geometry and the minimal, non minimal, and new minimal supergravity multiplets
Energy Technology Data Exchange (ETDEWEB)
Girardi, G.; Grimm, R.; Mueller, M.; Wess, J.
1984-11-01
We analyse superspace constraints in a systematic way and define a set of natural constraints. We give a complete solution of the Bianchi identities subject to these constraints and obtain a reducible, but not fully reducible multiplet. By additional constraints it can be reduced to either the minimal nonminimal or new minimal multiplet. We discuss the superspace actions for the various multiplets.
2016-01-01
The evolution of event displays - Video by Riccardo Maria Bianchi, Emma Ward & Katarina Anthony Based on the video "VP1: the history, the status and the future of event visualization" available here: https://indico.cern.ch/event/388328/contributions/1820020/ Event displays courtesy of Brookhaven National Laboratory, CERN, DESY and Fermilab
Efficient Optimization of Control Libraries
2011-06-01
through the Autonomous Robotic Manipulation Soft- ware Track (ARM-S). References [1] URL http://youtube.com/robotcontrol1. [2] P. Auer, N. Cesa ...Branicky, R.A. Knepper, and J.J. Kuffner. Path and trajectory diversity: Theory and algorithms. In ICRA, pages 1359–1364. IEEE, 2008. [6] N. Cesa -Bianchi
and Models: A Self-Similar Approach
Directory of Open Access Journals (Sweden)
José Antonio Belinchón
2013-01-01
equations (FEs admit self-similar solutions. The methods employed allow us to obtain general results that are valid not only for the FRW metric, but also for all the Bianchi types as well as for the Kantowski-Sachs model (under the self-similarity hypothesis and the power-law hypothesis for the scale factors.
Inflation in Einstein-Cartan theory with energy-momentum tensor with spin
Fennelly, A. J.; Bradas, James C.; Smalley, Larry L.
1988-01-01
Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic (Bianchi Type I) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley (RS) improved energy-momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density.
Kakskümmend üheksa / Juhapekka Tukiainen
Tukiainen, Juhapekka
2013-01-01
TMi test: 29tollised maastikurattad, hinnaklass 1500 eurot. Bianchi Jab 29.2; Canyon Grand Canyon 8.9 AL 29; Corratec Superbow Team 29; Cube LTD SL 29; Felt Nine 30; Kona Kahuna DL; KTM Ultra Race 29; Merida Big Nine TFS XT Edition
Causal Propagation of Constraints in General Relativity
York, James W
2015-01-01
In this paper, I demonstrate that the constraint functions are propagated by a first order symmetric (or symmetrizable) hyperbolic system whose characteristic cone is the light cone. This result follows from the twice-contracted Bianchi identities. Analyticity is not required.
Indian Academy of Sciences (India)
B B Bhowmik; A Rajput
2004-06-01
Anisotropic Bianchi Type-I cosmological models have been studied on the basis of Lyra's geometry. Two types of models, one with constant deceleration parameter and the other with variable deceleration parameter have been derived by considering a time-dependent displacement field.
Changing Families, Changing Workplaces
Bianchi, Suzanne M.
2011-01-01
American families and workplaces have both changed dramatically over the past half-century. Paid work by women has increased sharply, as has family instability. Education-related inequality in work hours and income has grown. These changes, says Suzanne Bianchi, pose differing work-life issues for parents at different points along the income…
Bagatellid : maailm / Nele-Eva Steinfeld, Ivo Heinloo
Steinfeld, Nele-Eva
2011-01-01
Muusikasõnumeid maailmast: Helsingis avati uus kultuurikeskus Helsingi Musiikkitalo. Montrealis sain endale uue kontserdimaja La Maison Symphonique de Montreal. Lahkus tenor Salvatore Licitra. James Levine loobus Metropolitan Opera sügishooaja etenduste dirigeerimisest. Iisraeli Filharmoonikute kontsert BBC Promsil häiritud. Deutsche Grammophon kolis Berliini. Siemens loobub Bayereuthi festivali spondeerimisest. Kultuurivahetus Viini Riigiooperi ja La Scala ooperiteatrite vahel. MTV premeeris popimaailma tippe. Hiina tsenseerib Lääne popmuusikuid. uus Grammyde jagamise kord põhjustab pahameelt. Return to Forever taas koos. Chick Corea juubel
Psychological changes in alcohol-dependent patients during a residential rehabilitation program
Directory of Open Access Journals (Sweden)
Giorgi I
2015-12-01
Full Text Available Ines Giorgi,1 Marcella Ottonello,2,3 Giovanni Vittadini,4 Giorgio Bertolotti5 1Psychology Unit, Salvatore Maugeri Foundation, Clinica del Lavoro e della Riabilitazione, IRCCS, Pavia, 2Department of Physical & Rehabilitation Medicine, Salvatore Maugeri Foundation, Clinica del Lavoro e della Riabilitazione, IRCCS, Genoa, 3Department of Medicine, PhD Program in Advanced Sciences and Technologies in Rehabilitation Medicine and Sport, Università di Tor Vergata, Rome, 4Alcohol Rehabilitation Unit, Salvatore Maugeri Foundation, Clinica del Lavoro e della Riabilitazione, IRCCS, Pavia, 5Psychology Unit, Salvatore Maugeri Foundation, Clinica del Lavoro e della Riabilitazione, IRCCS, Tradate, Italy Background: Alcohol-dependent patients usually experience negative affects under the influence of alcohol, and these affective symptoms have been shown to decrease as a result of alcohol-withdrawal treatment. A recent cognitive–affective model suggests an interaction between drug motivation and affective symptoms. The aim of this multicenter study was to evaluate the psychological changes in subjects undergoing a residential rehabilitation program specifically designed for alcohol addiction, and to identify at discharge patients with greater affective symptoms and therefore more at risk of relapse.Materials and methods: The sample included 560 subjects (mean age 46.91±10.2 years who completed 28-day rehabilitation programs for alcohol addiction, following a tailored routine characterized by short duration and high intensity of medical and psychotherapeutic treatment. The psychological clinical profiles of anxiety, depression, psychological distress, psychological well-being, and self-perception of a positive change were assessed using the Cognitive Behavioral Assessment – Outcome Evaluation questionnaire at the beginning and at the end of the program. The changes in the psychological variables of the questionnaire were identified and considered as outcome
Energy Technology Data Exchange (ETDEWEB)
Heidler, Fridolin [Universitaet der Bundeswehr Muenchen, Neubiberg (Germany). Inst. fuer Elektrische Energieversorgung
2009-01-15
Lightning protection measures are specified in the international standard series IEC 62305, which were integrated in European and German standards immediately upon publication in early 2006. The German version is the DIN EN 62 305 (VDE 0185-305). Investigations have shown that lightning currents present the biggest hazard. It is therefore the main danger at which all protective measures of the IEC 62305 standard series are aimed. The lightning current parameters to which the standards refer are based on long-term measurements carried out by Prof. Karl Berger on two telecommunication towers on San Salvatore mountain, Switzerland. (orig.)
1983-01-01
ITALY 1,010 1,010 COLLODETTO ANGELO DI COLLODETTO E ITALY 483 483 CON FRA S R L ITALY 67 67 CONVERTINO FRANCESCO ITALY 288 288 COOPERATIVA DARSENA...PISANA ITALY 212 212 COOPERATIVA I P N ITALY 337 337 COPPOLA SALVATORE ITALY 121 121 COSTIERI D ALESIO S P A ITALY 482 482 COSTRUZIONI I S E SRL ITALY 120...THOUSANDS) CONTRACTOR CITY STATE AGGREGATE ARMY NAVY AI R FORCE OLA OCE ENGINE CENVER INC MEXICO 34 34 NORTHROP CORP MEXICO 414 414 TEXAS TURUG JET INC
O espelho partido de Oscar Wilde
Directory of Open Access Journals (Sweden)
Marcus Rodrigues Jacobina Vieira
2015-12-01
Full Text Available Este artigo tece algumas considerações a respeito dos processos de luto e melancolia, dos desafios que surgem à elaboração de lutos e perdas. Foi inspirado na teoria psicanalítica e na leitura de alguns aspectos da vida de Oscar Wilde extraídos de sua biografia, escrita por Daniel Salvatore Schiffer, para iluminar a mesma problemática de inibição do luto, conduzindo à melancolia e ao empobrecimento da criatividade.
Bagatellid : maailm / Nele-Eva Steinfeld, Ivo Heinloo
Steinfeld, Nele-Eva
2011-01-01
Muusikasõnumeid maailmast: Helsingis avati uus kultuurikeskus Helsingi Musiikkitalo. Montrealis sain endale uue kontserdimaja La Maison Symphonique de Montreal. Lahkus tenor Salvatore Licitra. James Levine loobus Metropolitan Opera sügishooaja etenduste dirigeerimisest. Iisraeli Filharmoonikute kontsert BBC Promsil häiritud. Deutsche Grammophon kolis Berliini. Siemens loobub Bayereuthi festivali spondeerimisest. Kultuurivahetus Viini Riigiooperi ja La Scala ooperiteatrite vahel. MTV premeeris popimaailma tippe. Hiina tsenseerib Lääne popmuusikuid. uus Grammyde jagamise kord põhjustab pahameelt. Return to Forever taas koos. Chick Corea juubel
Law, science and literature in post-unitarian Italy: the Misdea case
Directory of Open Access Journals (Sweden)
Alessio Berrè
2012-04-01
Full Text Available Il saggio si concentra sul processo a Salvatore Misdea, condannato a morte nonostante Cesare Lombroso l’avesse dichiarato “imbecille morale”, e sul romanzo giudiziario scritto da Edoardo Scarfoglio in risposta a questa sentenza. Analizzando il caso Misdea alla luce delle trasformazioni del mondo giudiziario postunitario, risulta evidente il coinvolgimento della narrazione letteraria all’interno dello scontro tra le scuole penali. L’opera di Scarfoglio, in questo caso straordinariamente fedele al dettato della nuova antropologia criminale, dimostra come la letteratura abbia contribuito alla costruzione culturale del criminale-folle.
Institute of Scientific and Technical Information of China (English)
Sanpig; 罗浩（摄影）
2009-01-01
＂You are the best dressed tonight… and…, may I have a cigarette？＂这句台词儿绝对可被纳入夜场搭讪经典语录中，但如果对应上Salvatore Ferragamo 80周年派对当晚Vino那一袭绣满银色珠片的深紫晚礼裙，这就不是一句单纯的搭讪，而是一句由衷的赞美了。
Effects of the protein corona on liposome–liposome and liposome–cell interactions
Corbo C; Molinaro R; Taraballi F; Toledano Furman NE; Sherman MB; Parodi A; Salvatore F; Tasciotti E
2016-01-01
Claudia Corbo,1,2 Roberto Molinaro,1 Francesca Taraballi,1 Naama E Toledano Furman,1 Michael B Sherman,3 Alessandro Parodi,1 Francesco Salvatore,2,4 Ennio Tasciotti1,5 1Center for Biomimetic Medicine, Houston Methodist Research Institute, Houston, TX, USA; 2CEINGE-Biotecnologie Avanzate s.c.a r.l., Naples, Italy; 3Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA; 4Department ...
Learning Classical Music Club
2010-01-01
There is a new CERN Club called “Learning Classical Music at CERN”. We are aiming to give classical music lessons for different instruments (see link) for students from 5 to 100 years old. We are now ready to start our activities in the CERN barracks. We are now in the enrollment phase and hope to start lessons very soon ! Club info can be found in the list of CERN Club: http://user.web.cern.ch/user/Communication/SocialLifeActivities/Clubs/Clubs.html Salvatore Buontempo Club President
Pegylated liposomal doxorubicin in the management of ovarian cancer
Directory of Open Access Journals (Sweden)
Gabriella Ferrandina
2010-09-01
Full Text Available Gabriella Ferrandina1,2, Giacomo Corrado1, Angelo Licameli1, Domenica Lorusso2, Gilda Fuoco1, Salvatore Pisconti3, Giovanni Scambia2 1Gynecologic Oncology Unit, Department of Oncology, Catholic University of Campobasso, Campobasso, Italy; 2Gynecologic Oncology Unit, Catholic University of Rome, Rome, Italy; 3Salvatore Pisconti, Oncology Unit, Taranto Hospital, Taranto, Italy Abstract: Among the pharmaceutical options available for treatment of ovarian cancer, much attention has been progressively focused on pegylated liposomal doxorubicin (PLD, whose unique formulation, which entraps conventional doxorubicin in a bilayer lipidic sphere surrounded by a polyethylene glycol layer, prolongs the persistence of the drug in the circulation and potentiates intratumor drug accumulation. These properties enable this drug to sustain its very favorable toxicity profile and to be used safely in combination with other drugs. PLD has been already approved for treatment of advanced ovarian cancer patients failing first-line platinum-based treatment. Moreover, phase III trials have been already completed, and results are eagerly awaited, which hopefully will expand the range of PLD clinical application in this neoplasia both in front-line treatment, and in the salvage setting in combination with other drugs. Moreover, attempts are continuing to enable this drug to be combined with novel cytotoxic drugs and target-based agents. This review aims at summarizing the available evidence and the new perspectives for the clinical role of PLD in the management of patients with epithelial ovarian cancer.Keywords: pegylated liposomal doxorubicin, ovarian cancer, clinical trials
Advanced methods for the study of PWR cores; Les methodes d'etudes avancees pour les coeurs de REP
Energy Technology Data Exchange (ETDEWEB)
Lambert, M.; Salvatores, St.; Ferrier, A. [Electricite de France (EDF), Service Etudes et Projets Thermiques et Nucleaires, 92 - Courbevoie (France); Pelet, J.; Nicaise, N.; Pouliquen, J.Y.; Foret, F. [FRAMATOME ANP, 92 - Paris La Defence (France); Chauliac, C. [CEA Saclay, Dir. de l' Energie Nucleaire (DEN), 91 - Gif sur Yvette (France); Johner, J. [CEA Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint Paul lez Durance (France); Cohen, Ch
2003-07-01
This document gathers the transparencies presented at the 6. technical session of the French nuclear energy society (SFEN) in October 2003. The transparencies of the annual meeting are presented in the introductive part: 1 - status of the French nuclear park: nuclear energy results, management of an exceptional climatic situation: the heat wave of summer 2003 and the power generation (J.C. Barral); 2 - status of the research on controlled thermonuclear fusion (J. Johner). Then follows the technical session about the advanced methods for the study of PWR reactor cores: 1 - the evolution approach of study methodologies (M. Lambert, J. Pelet); 2 - the point of view of the nuclear safety authority (D. Brenot); 3 - the improved decoupled methodology for the steam pipe rupture (S. Salvatores, J.Y. Pouliquen); 4 - the MIR method for the pellet-clad interaction (renovated IPG methodology) (E. Baud, C. Royere); 5 - the improved fuel management (IFM) studies for Koeberg (C. Cohen); 6 - principle of the methods of accident study implemented for the European pressurized reactor (EPR) (F. Foret, A. Ferrier); 7 - accident studies with the EPR, steam pipe rupture (N. Nicaise, S. Salvatores); 8 - the co-development platform, a new generation of software tools for the new methodologies (C. Chauliac). (J.S.)
Staff Association
2016-01-01
The Elementary Particles of Painting Alfonso Fratteggiani Bianchi and Ermanno Imbergamo From September 26 to October 7, 2016 CERN Meyrin, Main Building With intentions similar to those of CERN physicists, the artist Alfonso Fratteggiani Bianchi investigates the color pigment, studying its interaction with light and with the support on which it is deposited. He creates monochrome paintings by spreading the color pigment in the pure state on stones, without using glue or any other type of adhesive. With intentions similar to artists, the physicist Ermanno Imbergamo investigates the use of luminescent wavelength shifters, materials commonly used in Particle Physics, for art. He creates other monochrome artworks, which disclose further aspects of interaction among light, color pigments and support. For more information: staff.association@cern.ch | Tel: 022 767 28 19
The anisotropic cosmological models in $f (R, T)$ gravity with $\\Lambda (T)$
Indian Academy of Sciences (India)
R CHAUBEY; A K SHUKLA
2017-04-01
The general class of anisotropic Bianchi cosmological models in $f(R, T)$ modified theories of gravity with $\\Lambda (T)$ has been considered. This paper deals with $f(R, T)$ modified theories of gravity, where the gravitational Lagrangian is given by an arbitrary function of Ricci scalar $R$ and the trace of the stress-energy tensor $T$ has been investigated for a specific choice of $f (R,T )$ = $f_{1}(R) + f_{2}(T)$. The exact solutions to the corresponding field equations are obtained in quadrature form. We have discussed three types of solutions of the average scale factor for the general class of Bianchi cosmological models by using a special law for deceleration parameter which is linear in time with a negative slope. The solutions to the Einstein field equations are obtained for three differentphysical viable cosmologies. All physical parameters are calculated and discussed in each model.
University of Ferrara strengthens partnership with CERN
2006-01-01
Professor Patrizio Bianchi, Head of the University of Ferrara, and Robert Aymar, CERN Director-General, signing an agreement to support the Doctoral Student Programme. The Head of the University of Ferrara, in Italy, Professor Patrizio Bianchi, visited CERN on 6 June. After a visit of the LHCb experiment, he met the Director-General, Robert Aymar, and signed an administrative agreement aiming to enhance the participation of doctoral students from the University of Ferrara in the CERN Doctoral Student Programme. Under this agreement, Ferrara students who are selected for the CERN Doctoral Programme will receive significant financial support from their home institution. Following the signature of the agreement, the Head of Ferrara University and the Secretary-General attented a lunch with representatives of the CERN Management, the LHCb experiment and the Italian Ministry for Research. The lunch was followed by a visit of the ATLAS experiment in the afternoon.
Conference: Diversity in the Workplace - How to Capitalise on Differences to Foster Innovation
2012-01-01
Diversity in the Workplace: How to Capitalise on Differences to Foster Innovation, by Cristina Bianchi. Tuesday 19 June 2012 – 12 noon to 2 p.m. Brasserie Restaurant 2 Diversity Lunch : Lunchtime conference organised by the CERN Diversity Programme. Diversity is an acknowledged source of creativity and innovation that can improve performance and ultimately create a definite advantage for the Organization. However, if not managed well both at team and individual level, it can become a source of misunderstanding, interpersonal tensions and conflict. The speaker will share concrete strategies and approaches to capitalise on a diverse workforce and create the right environment where differences become an asset that leads to creativity, idea generation and, ultimately, innovation. Cristina Bianchi is specialised in conflict management, cross-cultural relations and effective communication and has acquired valuable experience working in sensitive areas such as Palestine and Kosovo. Her se...
Lorentzian three-metrics with degenerate Ricci tensors
McManus, Des J.
1995-03-01
A classification of Lorentzian three-metrics whose Ricci tensor satisfies Rij=λ1gij+λ2vivj with λ1 and λ2(≠0) constant where vivi=κ(=0 or ±1) is given. An explicit coordinate representation is given for all the metrics that admit a G4 group as their maximal isometry group. Those metrics that admit a G3 as their maximal isometry group belong to either Bianchi class VI0, or VII0, or VIII, or IX when κ ≠ 0, and to either Bianchi class III, or IV, or VI0, VIh, or VIII when κ=0. An explicit coordinate representation is given for all the inhomogeneous solutions in the case κ ≠ 0.
The anisotropic cosmological models in f( R, T) gravity with Λ(T)
Chaubey, R.; Shukla, A. K.
2017-04-01
The general class of anisotropic Bianchi cosmological models in f( R, T) modified theories of gravity with Λ( T) has been considered. This paper deals with f( R, T) modified theories of gravity, where the gravitational Lagrangian is given by an arbitrary function of Ricci scalar R and the trace of the stress-energy tensor T has been investigated for a specific choice of f( R, T) = f 1( R) + f 2( T). The exact solutions to the corresponding field equations are obtained in quadrature form. We have discussed three types of solutions of the average scale factor for the general class of Bianchi cosmological models by using a special law for deceleration parameter which is linear in time with a negative slope. The solutions to the Einstein field equations are obtained for three different physical viable cosmologies. All physical parameters are calculated and discussed in each model.
Characterisation of orthogonal perfect fluid cosmological spacetimes
Dadhich, N K; Govinder, K S; Leach, P G L; Dadhich, Naresh; Patel, L K; Govinder, K S; Leach, P G L
1994-01-01
We consider the general orthogonal metric separable in space and time variables in comoving coordinates. We then characterise perfect fluid models admitted by such a metric. It turns out that the homogeneous models can only be either FLRW or Bianchi I while the inhomogeneous ones can only admit G_2 (two mutually as well as hypersurface orthogonal spacelike Killing vectors) isometry. The latter can possess singularities of various kinds or none. The non-singular family is however unique and cylindrically symmetric.
Accelerating anisotropic cosmological model in f(R,T) theory of gravity
Santhi Kumar, R.; Satyannarayana, B.
2017-10-01
Field equations in a modified theory of gravitation proposed by Harko et al. (Phys Rev D 84:024020, 8) are obtained with the aid of a spatially homogeneous and anisotropic LRS Bianchi type-I metric. Cosmological models corresponding to false vacuum and dust universe are obtained. Some physical and kinematical properties of each of the models are discussed. These models may be physically significant for discussion at an early stage of evolution of the universe.
Cosmic no-hair conjecture in scalar–tensor theories
Indian Academy of Sciences (India)
T Singh; R Chaubey
2006-12-01
We have shown that, within the context of scalar–tensor theories, the anisotropic Bianchi-type cosmological models evolve towards de Sitter Universe. A similar result holds in the case of cosmology in Lyra manifold. Thus the analogue of cosmic no-hair theorem of Wald [1] hold in both the cases. In fact, during inflation there is no difference between scalar–tensor theories, Lyra's manifold and general relativity (GR).
Gauge-flation and Cosmic No-Hair Conjecture
Maleknejad, A; Soda, Jiro
2011-01-01
Gauge-flation, inflation from non-Abelian gauge fields, was introduced in [1,2]. In this work, we study the cosmic no-hair conjecture in gauge-flation. Starting from Bianchi-type I cosmology and through analytic and numeric studies we demonstrate that the isotropic FLRW inflation is an attractor of the dynamics of the theory and that the anisotropies are damped within a few e-folds, in accord with the cosmic no-hair conjecture.
Magnetized cosmological models in bimetric theory of gravitation
Indian Academy of Sciences (India)
S D Katore; R S Rane
2006-08-01
Bianchi type-III magnetized cosmological model when the field of gravitation is governed by either a perfect fluid or cosmic string is investigated in Rosen's [1] bimetric theory of gravitation. To complete determinate solution, the condition, viz., = (), where is a constant, between the metric potentials is used. We have assumed different equations of state for cosmic string [2] for the complete solution of the model. Some physical and geometrical properties of the exhibited model are discussed and studied.
Evaluation of Data Processing Techniques for Unobtrusive Gait Authentication
2014-03-01
characteristics of an individual, distinguishable from those of other individuals. Originally described by Bianchi et al. [10], the different biomechanical ...devices,” Pervasive Computing, K. Fishkin, B. Schiele, P. Nixon, and A. Quigley, Eds, Berlin, DE: Springer Berlin Heidelberg, Lecture Notes in Computer...gait recognition,” Biometrics, A.K. Jain, R. Bolle, and S. Pankanti, Eds. New York, NY: Springer USA, ch. 11, pp. 231–249, 1996. [14] J. Han and B
Well posed reduced systems for the Einstein equations
Choquet-Bruhat, Y
1996-01-01
We review some well posed formulations of the evolution part of the Cauchy problem of General Relativity that we have recently obtained. We include also a new first order symmetric hyperbolic system based directly on the Riemann tensor and the full Bianchi identities. It has only physical characteristics and matter sources can be included. It is completely equivalent to our other system with these properties.
Particle creation with finite energy density
Dray, Tevian; Renn, Jürgen; Salisbury, Donald
1983-03-01
We consider the semiclassical quantization of the Klein—Gordon field on a Robertson—Walker background with a flat-out region. We show that the requirement that the energy density of created particles be finite selects a preferred equivalence class of particle definitions. We present a representative element of the equivalence class so determined. We briefly discuss the generalization to Bianchi I spacetimes, and the case of an external Maxwell field.
Inhomogeneous Einstein-Rosen string cosmology
Clancy, Dominic; Feinstein, Alexander; Lidsey, James E.; Tavakol, Reza
1999-08-01
Families of anisotropic and inhomogeneous string cosmologies containing non-trivial dilaton and axion fields are derived by applying the global symmetries of the string effective action to a generalized Einstein-Rosen metric. The models exhibit a two-dimensional group of Abelian isometries. In particular, two classes of exact solutions are found that represent inhomogeneous generalizations of the Bianchi type VIh cosmology. The asymptotic behavior of the solutions is investigated and further applications are briefly discussed.
Homogeneous Universes in Extended Inflation II
Guzmán, Enrique
1997-04-01
It is shown that the scalar field π of the Brans-Dicke theory in the Bianchi TypeVIo-VIh-VIIh-VIII and IX models has the same form that in the isotropic Robertson-Walker case. It is shown that the Universe will be isotropized very fast, permitting so that the approximation of an Universe Robertson-Walker isotropic to be a good approach in the early Universe.
Effect of inflation on anisotropic cosmologies
Energy Technology Data Exchange (ETDEWEB)
Jensen, L.G.; Stein-Schabes, J.A.
1986-03-01
The effects of anisotropic cosmologies on inflation are studied. By properly formulating the field equations it is possible to show that any model that undergoes sufficient inflation will become isotropic on scales greater than the horizon today. Furthermore, we shall show that it takes a very long time for anisotropies to become visible in the observable part of the Universe. It is interesting to note that the time scale will be independent of the Bianchi Model and of the initial anisotropy. 6 refs.
Digital Repository Service at National Institute of Oceanography (India)
Krishna, M.S.; Prasad, V.R.; Sarma, V.V.S.S.; Reddy, N.P.C.; Hemalatha, K.P.J.; Rao, Y.V.
[Bin and Longjun, 2011], domestic and industrial sewage, besides the input from autochthonous sources, such as phytoplankton [Carlson et al., 1994; Bianchi et al., 2004], bacteria and macrophytes [Bronk et al., 1994; Diaz and Raimbault, 2000... transport in the Columbia River, Estuar. Coast. Shelf Sci., 13, 645-658. Diaz, F., and P. Raimbault (2000), Nitrogen regeneration and dissolved organic nitrogen release during spring in a NW Mediterranean coastal zone (Gulf of Lions): implications...
Spacetimes with Killing tensors. [for Einstein-Maxwell fields with certain spinor indices
Hughston, L. P.; Sommers, P.
1973-01-01
The characteristics of the Killing equation and the Killing tensor are discussed. A conformal Killing tensor is of interest inasmuch as it gives rise to a quadratic first integral for null geodesic orbits. The Einstein-Maxwell equations are considered together with the Bianchi identity and the conformal Killing tensor. Two examples for the application of the considered relations are presented, giving attention to the charged Kerr solution and the charged C-metric.
Anisotropic Friedmann-Robertson-Walker universe from nonlinear massive gravity
Gumrukcuoglu, A Emir; Mukohyama, Shinji
2012-01-01
In the scope of the nonlinear massive gravity, we study fixed points of evolution equations for a Bianchi type--I universe. We find a new attractor solution with non-vanishing anisotropy, on which the physical metric is isotropic but the Stuckelberg configuration is anisotropic. As a result, at the background level, the solution describes a homogeneous and isotropic universe, while a statistical anisotropy is expected from perturbations, suppressed by smallness of the graviton mass.
Helical superconducting black holes.
Donos, Aristomenis; Gauntlett, Jerome P
2012-05-25
We construct novel static, asymptotically five-dimensional anti-de Sitter black hole solutions with Bianchi type-VII(0) symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have a vanishing entropy and approach domain wall solutions that reveal homogenous, nonisotropic dual ground states with an emergent scaling symmetry.
The space of signed points and the Self Dual Model
Leal, L C
2002-01-01
We study a generalization of the group of loops based on sets of signed points, instead of paths or loops. This geometrical setting incorporates the kinematical constraints of the Sigma Model, inasmuch as the the group of loops does with the Bianchi identities of Yang-Mills theories. We employ an Abelian version of this construction to quantize the Self-Dual Model, which allows us to relate this theory with that of a massless scalar field obeying non-trivial boundary conditions.
Gravitational Baryogenesis in Anisotropic Universe
Saaidi, Kh
2010-01-01
The interaction between Ricci scalar curvature and the baryon number current, dynamically breaks CPT in an expanding universe and leads to baryon asymmetry. Using this kind of interaction and study the gravitational baryogenesis in the Bianchi type I universe. We find out the effect of anisotropy of the universe on the baryon asymmetry for the case which the equation of state parameter, $\\omega$, is dependent to time.
Novaes, Marcos Carneiro; Bispo, Pitágoras Da Conceição
2014-02-20
Specimens of Perlidae (Plecoptera) deposited in the Entomological Collection "Padre Jesus S. Moure" of the Universidade Federal do Paraná and additional material recently collected in Paraná and Santa Catarina states, Brazil were studied. Six previously described species were identified, Anacroneuria debilis (Pictet, 1841), A. cathia Froehlich, 2002, A. polita (Burmeister, 1839), A. trimacula Jewett, 1959, Kempnyia neotropica (Jacoson and Bianchi, 1905) and K. colossica (Navás, 1934). Additionally, a new species, Anacroneuria iguazu n. sp is described.
An Approach to Loop Quantum Cosmology Through Integrable Discrete Heisenberg Spin Chains
Dantas, Christine C
2012-01-01
The quantum evolution equation of Loop Quantum Cosmology (LQC) -- the quantum Hamiltonian constraint -- is a difference equation. We relate the LQC constraint equation in vacuum Bianchi I separable (locally rotationally symmetric) models with an integrable differential-difference nonlinear Schr\\"odinger type equation, which in turn is known to be associated with integrable, discrete Heisenberg spin chain models in condensed matter physics. We illustrate the similarity between both systems with a simple constraint in the linear regime.
Nacir, Diana López
2009-01-01
We review our recent results on the renormalization procedure for a free quantum scalar field with modified dispersion relations in curved spacetimes. For dispersion relations containing up to $2s$ powers of the spatial momentum, the subtraction necessary to renormalize $$ and $$ depends on $s$. We first describe our previous analysis for spatially flat Friedman-Robertson-Walker and Bianchi type I metrics. Then we present a new power counting analysis for general background metrics in the weak field approximation.
Relabeling symmetries in hydrodynamics and magnetohydrodynamics
Energy Technology Data Exchange (ETDEWEB)
Padhye, N.; Morrison, P.J.
1996-04-01
Lagrangian symmetries and concomitant generalized Bianchi identities associated with the relabeling of fluid elements are found for hydrodynamics and magnetohydrodynamics (MHD). In hydrodynamics relabeling results in Ertel`s theorem of conservation of potential vorticity, while in MHD it yields the conservation of cross helicity. The symmetries of the reduction from Lagrangian (material) to Eulerian variables are used to construct the Casimir invariants of the Hamiltonian formalism.
The generic model of General Relativity
Energy Technology Data Exchange (ETDEWEB)
Tsamparlis, Michael, E-mail: mtsampa@phys.uoa.g [Department of Physics, Section Astrophysics Astronomy Mechanics, University of Athens, University of Athens, Zografos 15783, Athens (Greece)
2009-10-01
We develop a generic spacetime model in General Relativity from which all existing model results are produced under specific assumptions, depending on the case. We classify each type of possible assumption, especially the role of observers and that of symmetries, and discuss their role in the development of a model. We apply the results in a step by step approach to the case of a Bianchi I spacetime and a string fluid.
1984-07-01
Cultural Differences Equity research has been conducted in both Europe (e.g., Mikula, 1981; Pepitone, Faucheux, Moscovici , Cesa-Bianchi, Magistretti... Moscovici (1972) is correct in observing the geographical limitation of equity theory, although his prediction that equity is particular to capital...n i n i l _ i . . . . i . ... .. . . . . 32 Moscovici , S. (1972). Society and theory in social psychology. In J. Israel & H. Tajfel (Eds.), The
Kaluza-Klein mixmaster universes
Energy Technology Data Exchange (ETDEWEB)
Barrow, J.D.; Stein-Schabes, J.
1985-09-15
We analyze the behavior of some Bianchi type-IX, mixmaster cosmological models possessing extra dimensions. We find that, unlike the three-dimensional case, they do not exhibit chaotic behavior on approach to their initial singularity. A finite sequence of stochastic mixmaster oscillations is, in general, replaced by monotonic contraction of the three-space scale factors on approach to a singularity whenever additional spatial dimensions exist with the metric form we consider.
Effect of inflation on anisotropic cosmologies
Energy Technology Data Exchange (ETDEWEB)
Jensen, L.G.; Stein-Schabes, J.A.
1986-08-15
We study the effects of anisotropic cosmologies on inflation. By properly formulating the field equations it is possible to show that any model that undergoes sufficient inflation will become isotropic on scales greater than the horizon today. Furthermore, we shall show that it takes a very long time for anisotropies to become visible in the observable part of the Universe. It is interesting to note that the time scale will be independent of the Bianchi model and of the initial anisotropy.
Non-diagonal four-dimensional cohomogeneity-one Einstein metrics in various signatures
Dunajski, Maciej
2016-01-01
Most known four-dimensional cohomogeneity-one Einstein metrics are diagonal in the basis defined by the left-invariant one-forms, though some essentially non-diagonal ones are known. We consider the problem of explicitly seeking non-diagonal Einstein metrics, and we find solutions which in some cases exhaust the possibilities. In particular we construct new examples of neutral signature non--diagonal Bianchi type VIII Einstein metrics with self--dual Weyl tensor.
Moduli Spaces of Transverse Deformations of Near-Horizon Geometries
Fontanella, A
2016-01-01
We investigate deformations of extremal near-horizon geometries in Einstein-Maxwell-Dilaton theory, including various topological terms, and also in D=11 supergravity. By linearizing the field equations and Bianchi identities over the compact spatial cross-sections of the near-horizon geometry, we prove that the moduli associated with such deformations are constrained by elliptic systems of PDEs. The moduli space of deformations of near-horizon geometries in these theories is therefore shown to be finite dimensional.
The Maxwell-Chern-Simons gravity, and its cosmological implications
Haghani, Zahra; Harko, Tiberiu; Shahidi, Shahab
2017-08-01
We consider the cosmological implications of a gravitational theory containing two vector fields coupled via a generalized Chern-Simons term. One of the vector fields is the usual Maxwell field, while the other is a constrained vector field with constant norm included in the action via a Lagrange multiplier. The theory admits a de Sitter type solution, with healthy cosmological perturbations. We also show that there are seven degrees of freedom that propagate on top of de Sitter space-time, consisting of two tensor polarizations, four degrees of freedom related to the two vector fields, and a scalar degree of freedom that makes one of the vector fields massive. We investigate the cosmological evolution of Bianchi type I space-time, by assuming that the matter content of the Universe can be described by the stiff and dust. The cosmological evolution of the Bianchi type I Universe strongly depends on the initial conditions of the physical quantities, as well as on the model parameters. The mean anisotropy parameter, and the deceleration parameter, are also studied, and we show that independently of the matter equation of state the cosmological evolution of the Bianchi type I Universe always ends in an isotropic de Sitter type phase.
Loop quantum cosmology: Anisotropies and inhomogeneities
Wilson-Ewing, Edward
In this dissertation we extend the improved dynamics of loop quantum cosmology from the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker space-times to cosmological models which allow anisotropies and inhomogeneities. Specifically, we consider the cases of the homogeneous but anisotropic Bianchi type I, II and IX models with a massless scalar field as well as the vacuum, inhomogeneous, linearly polarized Gowdy T3 model. For each case, we derive the Hamiltonian constraint operator and study its properties. In particular, we show how in all of these models the classical big bang and big crunch singularities are resolved due to quantum gravity effects. Since the Bianchi models play a key role in the Belinskii, Khalatnikov and Lifshitz conjecture regarding the nature of generic space-like singularities in general relativity, the quantum dynamics of the Bianchi cosmologies are likely to provide considerable intuition about the fate of such singularities in quantum gravity. In addition, the results obtained here provide an important step toward the full loop quantization of cosmological space-times that allow generic inhomogeneities; this would provide falsifiable predictions that could be compared to observations.
Iizuka, Norihiro; Kachru, Shamit; Kundu, Nilay; Narayan, Prithvi; Sircar, Nilanjan; Trivedi, Sandip P.; Wang, Huajia
2013-03-01
Classifying the zero-temperature ground states of quantum field theories with finite charge density is a very interesting problem. Via holography, this problem is mapped to the classification of extremal charged black brane geometries with anti-de Sitter asymptotics. In a recent paper [1], we proposed a Bianchi classification of the extremal near-horizon geometries in five dimensions, in the case where they are homogeneous but, in general, anisotropic. Here, we extend our study in two directions: we show that Bianchi attractors can lead to new phases, and generalize the classification of homogeneous phases in a way suggested by holography. In the first direction, we show that hyperscaling violation can naturally be incorporated into the Bianchi horizons. We also find analytical examples of "striped" horizons. In the second direction, we propose a more complete classification of homogeneous horizon geometries where the natural mathematics involves real four-algebras with three dimensional sub-algebras. This gives rise to a richer set of possible near-horizon geometries, where the holographic radial direction is non-trivially intertwined with field theory spatial coordinates. We find examples of several of the new types in systems consisting of reasonably simple matter sectors coupled to gravity, while arguing that others are forbidden by the Null Energy Condition. Extremal horizons in four dimensions governed by three-algebras or four-algebras are also discussed.
Lombardo, Davide M.; Riccioni, Fabio; Risoli, Stefano
2016-12-01
We consider the N = 1 superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of P fluxes, that are related by T-duality transformations to the S-dual of the Q flux. We determine the general rule that transforms a given flux in this family under a single T-duality transformation. This rule allows to derive a complete expression for the superpotential for both the IIA and the IIB theory for the particular case of a {T}^6/[{Z}_2× {Z}_2] orientifold. We then consider how these fluxes modify the generalised Bianchi identities. In particular, we derive a fully consistent set of quadratic constraints coming from the NS-NS Bianchi identities. On the other hand, the P flux Bianchi identities induce tadpoles, and we determine a set of exotic branes that can be consistently included in order to cancel them. This is achieved by determining a universal transformation rule under T-duality satisfied by all the branes in string theory.
Lombardo, Davide M; Risoli, Stefano
2016-01-01
We consider the ${\\cal N}=1$ superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of $P$ fluxes, that are related by T-duality transformations to the S-dual of the $Q$ flux. We determine the general rule that transforms a given flux in this family under a single T-duality transformation. This rule allows to derive a complete expression for the superpotential for both the IIA and the IIB theory for the particular case of a $T^6/[\\mathbb{Z}_2 \\times \\mathbb{Z}_2 ]$ orientifold. We then consider how these fluxes modify the generalised Bianchi identities. In particular, we derive a fully consistent set of quadratic constraints coming from the NS-NS Bianchi identities. On the other hand, the $P$ flux Bianchi identities induce tadpoles, and we determine a set of exotic branes that can be consistently included in order to cancel them. This is achieved by determining a universal transformation rule under T-duality satisfied by all the branes in string t...
PREFACE: Fourth Meeting on Constrained Dynamics and Quantum Gravity
Cadoni, Mariano; Cavaglia, Marco; Nelson, Jeanette E.
2006-04-01
) Georgi Dvali (NYU, USA) Sergio Ferrara (CERN) Gian Francesco Giudice (CERN) Roman Jackiw (MIT, USA) Edward W. Kolb (Fermilab, USA) Luca Lusanna (INFN Firenze, Italy) Roy Maartens (Univ. Portsmouth, UK) Hermann Nicolai (AEI, Potsdam, Germany) Tullio Regge (Politecnico di Torino, Italy) Augusto Sagnotti (Univ. Roma Tor Vergata, Italy) Kellogg S. Stelle (Imperial College London, UK) Ruth Williams (DAMTP, Cambridge, UK) SPONSORS Istituto Nazionale di Fisica Nucleare Università di Cagliari Università di Torino University of Mississippi Università di Pisa Regione autonoma della Sardegna Tiscali LIST OF PARTICIPANTS Eun-Joo Ahn (University of Chicago, USA) David Alba (Università di Firenze, Italy) Stanislav Alexeyev (Lomonosov Moscow State U., Russia) Damiano Anselmi (Università di Pisa, Italy) Ignatios Antoniadis (CERN, Geneva, Switzerland) Maria Da Conceicao Bento (Instituto Superior Técnico, Lisboa, Portugal) Orfeu Bertolami (Instituto Superior Técnico, Lisboa, Portugal) Massimo Bianchi (Università di Roma Tor Vergata, Italy) Mariam Bouhmadi-Lopez (University of Portsmouth, UK) Raphael Bousso (University of California at Berkeley, USA) Mariano Cadoni (Università di Cagliari, Italy) Steven Carlip (University of California at Davis, USA) Roberto Casadio (Università di Bologna, Italy) Marco Cavaglià (University of Mississippi, USA) Demian Cho (Raman Research Institute, Bangalore, India) Theodosios Christodoulakis (University of Athens, Greece) Chryssomalis Chryssomalakos (Inst. de Ciencias Nucleares - UNAM, Mexico) Diego Julio Cirilo-Lombardo (JINR, Dubna, Russia) Denis Comelli INFN, Sezione di Ferrara, Italy ) Ruben Cordero-Elizalde (Instituto Politecnico Nacional, Mexico) Lorenzo Cornalba (Università di Roma Tor Vergata, Italy) Branislav Cvetkovic (Institute of Physics, Belgrade, Serbia ) Maro Cvitan (University of Zagreb, Croatia) Alessandro D'Adda (Università di Torino, Italy) Claudio Dappiaggi (Università di Pavia, Italy) Roberto De Leo (Università di
Directory of Open Access Journals (Sweden)
Nicoletti G
2014-01-01
Full Text Available Giovanni Nicoletti,1–3 Andrea Sasso,1 Alberto Malovini,4,5 Luisa Ponchio,6 Silvia Scevola,2 Angela Faga,1–3 Aldo Pontone1 1Plastic and Reconstructive Surgery, Department of Clinical Surgical Diagnostic and Pediatric Sciences, 2Advanced Technologies for Regenerative Medicine and Inductive Surgery Research Centre, University of Pavia, Pavia, Italy; 3Plastic and Reconstructive Surgery Unit, Salvatore Maugeri Research and Care Institute, Pavia, Italy; 4Department of Computer Engineering and Systems Science, University of Pavia, Pavia, Italy; 5Laboratory of Informatics and Systems Engineering for Clinical Research, 6Oncology Unit, Salvatore Maugeri Research and Care Institute, Pavia, Italy Abstract: A randomized, prospective, controlled study was carried out at the Plastic and Reconstructive Surgery Unit of the University of Pavia, Salvatore Maugeri Research and Care Institute, Pavia, Italy, to evaluate the psychological benefits from corrective medical camouflage (CMC following surgical treatment for skin cancer of the face. Twenty-four female patients, following recovery from facial skin cancer surgery, were enrolled in the study over a period of 1 year. The study was performed using two health-related quality of life tests, the Satisfaction Profile (SAT-P test and the Body Uneasiness Test (BUT. The patients were randomized into two groups: group A, patients undergoing CMC; and group B, controls. Both the SAT-P and BUT demonstrated statistically significant better results in the treated patients versus the controls in the following functional parameters: Psychological Functionality (PsF, Physical Functionality (PhF, and Work Performance (WP for the SAT-P test and Compulsive Self-Monitoring (CSM for the BUT. The PsF demonstrated a better result 6 months post-treatment. Such a difference was particularly significant when comparing the performance at 6 months versus that at 3 months. The PhF demonstrated a better outcome at 6 months post
Planck 2015 results. XVIII. Background geometry and topology of the Universe
Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Feeney, S.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McEwen, J. D.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Peiris, H. V.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pogosyan, D.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, F.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.
2016-09-01
Maps of cosmic microwave background (CMB) temperature and polarization from the 2015 release of Planck data provide the highestquality full-sky view of the surface of last scattering available to date. This enables us to detect possible departures from a globally isotropic cosmology. We present the first searches using CMB polarization for correlations induced by a possible non-trivial topology with a fundamental domain that intersects, or nearly intersects, the last-scattering surface (at comoving distance χrec), both via a direct scan for matched circular patterns at the intersections and by an optimal likelihood calculation for specific topologies. We specialize to flat spaces with cubic toroidal (T3) and slab (T1) topologies, finding that explicit searches for the latter are sensitive to other topologies with antipodal symmetry. These searches yield no detection of a compact topology with a scale below the diameter of the last-scattering surface. The limits on the radius ℛi of the largest sphere inscribed in the fundamental domain (at log-likelihood ratio Δlnℒ > -5 relative to a simply-connected flat Planck best-fit model) are: ℛi > 0.97 χrec for the T3 cubic torus; and ℛi > 0.56 χrec for the T1 slab. The limit for the T3 cubic torus from the matched-circles search is numerically equivalent, ℛi > 0.97 χrec at 99% confidence level from polarization data alone. We also perform a Bayesian search for an anisotropic global Bianchi VIIh geometry. In the non-physical setting, where the Bianchi cosmology is decoupled from the standard cosmology, Planck temperature data favour the inclusion of a Bianchi component with a Bayes factor of at least 2.3 units of log-evidence. However, the cosmological parameters that generate this pattern are in strong disagreement with those found from CMB anisotropy data alone. Fitting the induced polarization pattern for this model to the Planck data requires an amplitude of -0.10 ± 0.04 compared to the value of + 1 if the
Energy Technology Data Exchange (ETDEWEB)
Antunes, Alberi
2008-07-01
This work presents the Physics of Source Driven Systems (ADS). It shows some statics and K{sub i}netics parameters of the reactor Physics and when it is sub critical, that are important in evaluation and definition of these systems. The objective is to demonstrate that there are differences in parameters when the reactor is critical. Moreover, the work shows the differences observed in the parameters for different calculation models. Two calculation methodologies are shown In this dissertation: Gandini and Salvatores and Dulla, and some parameters are calculated. The ANISN deterministic transport code is used in calculation in order to compare these parameters. In a subcritical configuration of IPEN-MB-01 Reactor driven by an external source some parameters are calculated. The conclusions about calculation realized are presented in end of work. (author)
Motility of magnetotactic bacteria/MTB to Geomagnetic fields
Hidajatullah-Maksoed, Fatahillah
2016-03-01
Bacteria with motility directed by a local geomagnetic fields have been observed in marine sediments'' discussed by R. Blakemore, 1975. Magnetotactic bacteria/MTB discovered in 1963 by Salvatore Bellini. For ``off-axis electron holography in the transmission electron microscope was used to correlates the physical & magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria'' sought ``single-domain magnetite in hemopelagic sediments'' from JF Stolz. Otherwise, for potential source of bioproducts- product meant from result to multiplier -of magnetotactic bacteria[ACV Araujo, et.al, 2014 ] of marine drugs retrieved the `measurement of cellular chemotaxis with ECIS/Taxis, from KM Pietrosimone, 2012, whereas after ``earth magnetic field role on small living models'' are other interpretation of ``taxis'' as a movement of a cell instead usual ``tax'' for yew's taxus cuspidate, hired car & taxes in financial realms. Acknowledgements to HE. Mr. H. TUK SETYOHADI, Jl. Sriwijaya Raya 3, South-Jakarta, INDONESIA.
Chapitre III. Tommaso Landolfi entre désir d’abandon et dégoût de l’informe
2016-01-01
Il est difficile de lire ces quelques lignes, écrites par Giovanni Verga dans une lettre adressée à l’intellectuel Salvatore Farina, pour lui présenter sa nouvelle L’amante di Gramigna (publiée en 1880), exemple typique du récit vériste tel que Verga souhaitait en écrire, sans penser au mythe de Pygmalion ou au livre de Mary Shelley publié en 1818 : Frankenstein ou le Prométhée moderne. Ainsi est-on tenté de voir ici une sorte d’hybris romantique qui s’exprimerait sous la plume de ce parangon...
Pneumolabyrinth secondary to temporal bone fracture: a case report and review of the literature
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Bacciu A
2014-09-01
Full Text Available Andrea Bacciu,1 Vincenzo Vincenti,1 Sampath Chandra Prasad,1 Daniela Tonni,1 Elisa Ventura,2 Salvatore Bacciu,1 Enrico Pasanisi1 1Department of Clinical and Experimental Medicine, Unit of Audiology and Paediatric Otolaryngology, 2Department of Neuroradiology, University Hospital of Parma, Parma, Italy Abstract: Pneumolabyrinth following temporal bone fracture is an extremely rare condition. It results from air entering the inner ear when a communication between the air-filled middle ear spaces and inner ear is established. The imaging modality of choice for pneumolabyrinth is high-resolution computed tomography of the temporal bone. Treatment options include conservative management (bed rest, antibiotics, corticosteroids or surgery (exploratory tympanotomy. We present the case of a 31-year-old female who had pneumolabyrinth secondary to a temporal bone fracture. The patient was treated surgically and made a full clinical recovery. Keywords: pneumolabyrinth, temporal bone fractures, head trauma
Βίος τῆς αὐτοκράτειρας Θεοδώρας (BHG 1731
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Αθανάσιος ΜΑΡΚΟΠΟΥΛΟΣ
1983-09-01
Full Text Available A. Markopoulos La Vie de l'impératrice Théodora (BHG 1731 La Vie de l'impératrice Théodora (BHG 1731 est éditée pour la première fois par W. Regel dans Analecta Byzantino-Russica, St. Petersbourg 1891, pp. 1-19, d'après le ms. British Museum Add. 28270, ff. 1 - 16v. La présente édition est fondée sur les trois mss. connus (British Museum Add. 28270, Messina, Bibl. Universitaria, San Salvatore 30, ff. 227-232v et Vaticanus gr. 2014, ff. 136v-143; l'édition est complétée d'un commentaire historique.
Minding money: how understanding of value is culturally promoted.
Sato, Tatsuya
2011-03-01
Adding to the issues of cognitive economics (Cortes and Londoño IPBS: Integrative Psychological & Behavioral Science 43(2):178-184, 2009) and the social psychology of "shadow economics" (Salvatore et al. IPBS: Integrative Psychological & Behavioral Science 43(2), 2009), the carrier of economic exchanges, money, plays a key role in children's socialization in different societies. Money given to children, 'pocket money,' is a negotiated settlement between children's social demands and those of their parents. I analyze such negotiations here on the basis of a concrete case of a Korean family in which the provision of pocket money given the child was inconsistent over time. The results indicate the social ecology of money use, in both children and their parents, sets the stage for value construction of the meaning of money.
Lo artístico y lo industrial el la estética del cine una propuesta de investigación
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Fernando Vizcarra
2002-01-01
Full Text Available The present text is a protocol of research whose principal objective is to identity and explore those aesthetic elements where the artistic ^rw.y and the industrial forms converge in the cinematographic discourse of three woiks representative of the variant of science fiction called cyberpunk. The films selected as units of analysis are Blade Runner (1982 Dir. Ridley Scott, Nirvana (1996. Dir. Gabirele Salvatores, and The Matrix (1999. Dir. Hermanos Wachowski. The central questions that guide this project are the following: How do the values of the movie industry and film as an art interrelate in a sample of films representative of cyberpunk? How is the aesthetic dimension of the cinematographic discourse of cyberpunk constituted? And how is the aesthetic configured when conceived as a communicative strategy in this type of film?
Diabetes mellitus: a prothrombotic state. Implications for outcomes after coronary revascularization
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Clarissa Cola
2009-01-01
Full Text Available Clarissa Cola1, Salvatore Brugaletta1, Victoria Martín Yuste1, Bieito Campos1, Dominick J Angiolillo2, Manel Sabaté11Interventional Cardiology Unit, Department of Cardiology, Sant Pau University Hospital, Barcelona, Spain; 2Interventional Cardiology Unit, Shands Jacksonville, University of Florida, Florida, USAAbstract: Coronary stent thrombosis is a serious problem in the drug-eluting stent era. Despite aggressive antiplatelet therapy during and after percutaneous coronary intervention (PCI, the incidence of sub-acute stent thrombosis remains approximately 0.5%–2%, which may represent a catastrophic clinical situation. Both procedural factors and discontinuation of antiplatelet therapy are normally associated with this event. We report on simultaneous stent thromboses of two drug-eluting stents implanted in two different vessels, which resulted in a life-threatening clinical condition. Possible contributing factors that led to synergistic thrombotic effects are discussed.Keywords: diabetes mellitus, platelet function, antiplatelet therapy, drug-eluting stent, stent thrombosis
Clinical and research data integration: the i2b2-FSM experience.
Segagni, Daniele; Tibollo, Valentina; Dagliati, Arianna; Malovini, Alberto; Zambelli, Alberto; Napolitano, Carlo; Priori, Silvia G; Bellazzi, Riccardo
2013-01-01
In order to support and improve the efficiency of clinical research in specific health area, the University of Pavia and the IRCCS Fondazione Salvatore Maugeri of Pavia (FSM) are developing and implementing an i2b2 based platform, designed to collect data coming from hospital clinical practice and scientific research. The work made in FSM is committed to support an affordable, less intrusive and more personalized care, increasing the quality of clinical practice as well as improving the scientific results. Such a aim depends on the application of information and communication technologies and the use of data. An integrated data warehouse has been implemented to support clinicians and researchers in two medical fields with a great impact on the population: oncology and cardiology. Furthermore the data warehouse approach has been tested with administrative information, allowing a financial view of clinical data.
Masonry structures between mechanics and architecture
Pedemonte, Orietta; Williams, Kim
2015-01-01
This book provides an overview of state of the art research in the mechanics of masonry structures. It continues the series Between Mechanics and Architecture, initially launched in 1995 from the collaboration of several renowned scholars, including Edoardo Benvenuto and Patricia Radelet-de Grave. The contributions in this volume represent the main approaches to the complex topic of masonry structures. In addition to historical studies, the mechanical behavior of masonry arches and structures is studied using different approaches (structural analysis, limit analysis, elastic analysis, plasticity, mathematical approaches, etc.), at times difficult to reconcile, at others intertwined and complementary. Readers will have the opportunity to compare different theoretical lines of inquiry and thus explore new horizons of research. Contributions by: Danila Aita Andrea Bacigalupo Riccardo Barsotti Stefano Bennati Antonio Brencich Mario Como Salvatore D’Agostino Luigi Gambarotta Jacques Heyman Santiago Huer...
Institute of Scientific and Technical Information of China (English)
齐屾
2008-01-01
如果说皮草可以彰显女性的高贵气质，那Salvatore Ferragamo的设计则让女人尝到了权力的甜头。偏男性化的西服裤装裙装已经不能满足这些手握权杖的Cleopatra女王了，她们的头脑已经掌握了时间，数字，人际关系……现在的她们，要无休止地展现作为一个权力党女性的美丽和高傲。
The physics of Ettore Majorana phenomenological, theoretical, and mathematical
Esposito, Salvatore
2015-01-01
Through just a handful of papers, Ettore Majorana left an indelible mark in the fields of physics, mathematics, computer science and even economics before his mysterious disappearance in 1938. It is only now that the importance of Majorana's work is being realised: Majorana fermions are intensely studied today, and his work on neutrino physics has provided possible explanations for the existence of dark matter. In this unique volume, Salvatore Esposito explores not only Majorana's known papers but, even more interestingly, unveils his unpublished works as well. These include powerful methods and results, ranging from the atomic two-centre problem, the Thomas-Fermi model and ferromagnetism to quasi-stationary states, n-component relativistic wave equations and quantum scalar electrodynamics. Featuring biographical notes and contributions from leading experts Evgeny Akhmedov and Frank Wilczek, this fascinating book will captivate graduate students and researchers interested in frontier science as well as in the...
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Bertolotti G
2016-10-01
Full Text Available Giorgio Bertolotti,1 Loretta Moroni,1 Roberto Burro,2 Antonio Spanevello,3 Roberto FE Pedretti,4 Giandomenico Giorgetti5 1Psychology Unit, Salvatore Maugeri Foundation, IRCCS, Scientific Institute, Tradate, 2Department of Human Sciences – University of Verona, Verona, 3Department of Cardiology, 4Division of Pulmonary Disease, 5Department of Neuromotor Rehabilitation, Salvatore Maugeri Foundation, IRCCS, Scientific Institute of Tradate, Italy Background: A postacute phase needs reliable routine screening instruments in order to identify the patients to be referred for a clinical interview with a psychologist. The aim of this study was to estimate the clinical cutoff scores of the anxiety and depression questionnaires and their clinical validity using a gold standard. Methods: The study involved 177 patients with pulmonary, cardiac, or neurological disease undergoing in-hospital rehabilitation. Receiver operating characteristic curves were used to determine the best concordance between questionnaire’s scores and the gold standards. Results: There was a significant difference (P<0.001 between clinically anxious and depressed patients and nonclinical subjects. The receiver operating characteristic curve for anxiety indicated that the best area under the curve for State Anxiety Inventory is obtained with a cutoff point of 21 for males and 25 for females; for depression scores, the highest area under the curve for Depression Questionnaire-Reduced Form is obtained with a cutoff point of six for males and eight for females. Conclusion: Using appropriate cutoff values, the State Anxiety Inventory and Depression Questionnaire-Reduced Form allow psychologists to optimize early clinical intervention strategies selecting patients with significant needs. Keywords: anxiety, depression, questionnaire, sensitivity and specificity, rehabilitation
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Cristina Sereno
2012-10-01
Full Text Available Di nessuna delle due mogli di Berengario I – Bertilla, la prima, un’aristocratica di origine supponide e Anna, la seconda, una principessa bizantina – si sono conservate le carte dei dotari. Di entrambe, inoltre, nessuna carta ricorda attività economiche o patrimoniali. Nel contesto familiare di Berengario I emerge però una delle due figlie, Berta, che fu badessa del monastero di San Salvatore di Brescia e poi anche, per nomina paterna, del monastero di San Sisto di Piacenza, fondato pochi decenni prima da Angelberga. Entrambi i monasteri avevano raccolto nei loro patrimoni larghe quote del fisco regio, spesso in prima istanza transitati nei dotari delle regine: le curtes e i monasteri dipendenti erano sparsi in tutta la parte settentrionale della penisola e, in taluni casi, oltrepassavano la linea degli Appennini. Berta appare così assumere presso la corte di Berengario una funzione di grande rilievo nella gestione e nella salvaguardia dei patrimoni di tali monasteri.Of none of the two wives of Berengar I - Bertilla, the first, an aristocratic woman from the Supponids and Anna, the second, a Byzantine princess - have been preserved dower charters; moreover no charter reminds businesses or assets. In the family context of Berengar I emerges, however, one of his two daughters, Berta, who was abbess of the monastery of St. Salvatore in Brescia and later, by his father's appointment, of the monastery of St. Sisto in Piacenza, founded a few decades earlier by Angelberga. Both monasteries were collected in their assets large shares of royal treasury, often in the first instance passed through in doweries of the queens: the curtes and the dependent monasteries were spread across the northern part of the peninsula and, in some cases, they passed the line of the Apennines. It looks like as at the court of Berengar Berta assumes a role of great importance in the management and safeguarding of the assets of these monasteries.
Causes of hospitalisation before and after the 2009 L'Aquila earthquake.
Petrazzi, L; Striuli, R; Polidoro, L; Petrarca, M; Scipioni, R; Struglia, M; Giorgini, P; Necozione, S; Festuccia, V; Ferri, C
2013-09-01
On 6 April 2009, an earthquake struck L'Aquila. The San Salvatore Hospital was evacuated, and a field hospital was built. The study aimed to assess the epidemiologic impact of the earthquake through the analysis of patient population admitted to the field hospital during a 2-month period following the disaster. We retrospectively evaluated causes of hospitalisation and demographic data of patients admitted to (i) the Division of Internal Medicine and (ii) the Division of Emergency Medicine of the field hospital from 6 April, 2009 to 29 May, 2009. All data were compared with the admissions made at the same divisions of the San Salvatore Hospital during the same period of previous year. (i) Patient group (n = 102) and comparison group (n = 108). Mean patient age was higher, patients living in L'Aquila were more numerous, while mean length of stay was lower after than before the earthquake. Infectious diseases increased, while 'other' diseases decreased after the disaster both in admission and in discharge diagnoses. Gastroenterological diseases decreased with the earthquake but only in admission diagnoses. (ii) Patient group (n = 5255) and comparison group (n = 6564). Triage codes changed with the earthquake. Cardiovascular, psychiatric, gynaecological, infectious and chronic diseases increased, while pneumologic, gastroenterological, traumatic and 'other' diseases decreased after the quake. The number of hospitalised patients decreased with the tremor, while those discharged transferred to other hospitals and those who rejected hospitalisation increased. A natural disaster completely changes causes of hospitalisation in the Divisions of Internal and Emergency Medicine. These findings can be useful for the design of specific intervention programmes and for softening the detrimental effects of quakes.
Biologic targeting in the treatment of inflammatory bowel diseases [Retraction
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Bosani M
2014-01-01
Full Text Available Bosani M, Ardizzone S, Porro GB. Biologics: Targets and Therapy. 2009;3:77–97.This paper has been retracted after we were made aware that it contains a large amount of reused, and uncited material that was not placed within quotation marks.The following statement has been supplied by Dr Sandro Ardizzone:The review entitled "Biologic targeting in the treatment of inflammatory bowel disease" has been commissioned by this journal and published in 2009 (Matteo Bosani, Sandro Ardizzone, Gabriele Bianchi Porro. Biologics: Targets & Therapy 2009;3:77–97. The paper was written by our young coworker (Dr M Bosani. He has consulted many papers, including our previous reviews published years before. The not perfect knowledge of English language has greatly influenced the writing of the paper itself. So he saved in word file several parts of our previous papers (Ardizzone S, Bianchi Porro G. Inflammatory bowel disease: new insights into pathogenesis and treatment. J Intern Med 2002;252:475–496 – Ardizzone S, Bianchi Porro G. Biologic therapy for inflammatory bowel disease. Drugs 2005:2253–2286, and then transferred to the final paper. He was unaware as we are, of the fact that he could not reuse previously published material in other journals. The reuse of this material was made in good faith.Taking our responsibility for what happened, we intend to apologize for this inconvenience to the Editor (Dr Doris Benbrook and Publisher (Dr Tim Hill. Moreover, for the reasons mentioned above, I consider appropriate to retract the paper itself.This retraction relates to this paper.
Mixmaster Horava-Witten Cosmology
Dabrowski, M P
2001-01-01
We discuss various superstring effective actions and, in particular, their common sector which leads to the so-called pre-big-bang cosmology (cosmology in a weak coupling limit of heterotic superstring). Then, we review the main ideas of the Horava-Witten theory which is a strong coupling limit of heterotic superstring theory. Using the conformal relationship between these two theories we present Kasner asymptotic solutions of Bianchi type IX geometries within these theories and make predictions about possible emergence of chaos. Finally, we present a possible method of generating Horava-Witten cosmological solutions out of the well-known general relativistic pre-big-bang solutions.
Integrable discretisations for a class of nonlinear Schrödinger equations on Grassmann algebras
Grahovski, Georgi G.; Mikhailov, Alexander V.
2013-12-01
Integrable discretisations for a class of coupled (super) nonlinear Schrödinger (NLS) type of equations are presented. The class corresponds to a Lax operator with entries in a Grassmann algebra. Elementary Darboux transformations are constructed. As a result, Grassmann generalisations of the Toda lattice and the NLS dressing chain are obtained. The compatibility (Bianchi commutativity) of these Darboux transformations leads to integrable Grassmann generalisations of the difference Toda and NLS equations. The resulting systems will have discrete Lax representations provided by the set of two consistent elementary Darboux transformations. For the two discrete systems obtained, initial value and initial-boundary problems are formulated.
Accretion of radiation and Primordial black holes in anisotropic universe
Mahapatra, Swapna
2013-01-01
We consider Primordial black holes (PBHs) in a LRS (locally rotationally symmetric) Bianchi-I anisotropic space time and study the effect of accretion of radiation in the radiation dominated era. We show that the life time of PBHs in anisotropic universe becomes longer by accretion of radiation. We generalize the result by including nonzero angular momentum parameter and study the PBH evolution equation. We find that the evaporation time gets prolonged and it depends on the accretion efficiency as well as angular momentum parameter. This supports the conjecture that Primordial black holes can be considered as a viable candidate for dark matter.
A mild source for the Wu-Yang magnetic monopole
Constantinidis, C P; Luchini, G
2016-01-01
We establish that the Wu-Yang monopole needs the introduction of a magnetic point source at the origin in order for it to be a solution of the integral equations for the Yang-Mills theory. That result is corroborated by the analysis of the differential Yang-Mills equations using distribution theory. The subtlety lies on the fact that with the non-vanishing magnetic point source required by the Yang-Mills integral equations, the Wu-Yang monopole configuration does not violate, in the sense of distribution theory, the differential Bianchi identity.
Instability of Meridional Axial System in f(R) Gravity
Sharif, M
2015-01-01
We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.
Magnetized Emergent Universe with Null Radiation Flow
Singh, J. K.; Rani, Sarita
2016-01-01
In this paper, we study the Bianchi type-I cosmological model in a different basic form incorporating with null radiation flow with the perfect fluid in the presence as well as absence of a source free magnetic field. A set of new exact solutions of Einstein field equations are obtained in both the cases. We observe that the emergent universe model with null radiation flow approaches to de-sitter universe at late time obeying the same rate of expansion in presence and absence of the magnetic field.
Cosmological models in general relativity
Indian Academy of Sciences (India)
B B Paul
2003-12-01
LRS Bianchi type-I space-time ﬁlled with perfect ﬂuid is considered here with deceleration parameter as variable. The metric potentials and are functions of as well as . Assuming '/=(), where prime denotes differentiation with respect to , it was found that =('/) and =(), where =() and is the scale factor which is a function of only. The value of Hubble’s constant 0 was found to be less than half for non-ﬂat model and is equal to 1.3 for a ﬂat model.
How Isotropic is the Universe?
Saadeh, Daniela; Feeney, Stephen M; Pontzen, Andrew; Peiris, Hiranya V; McEwen, Jason D
2016-09-23
A fundamental assumption in the standard model of cosmology is that the Universe is isotropic on large scales. Breaking this assumption leads to a set of solutions to Einstein's field equations, known as Bianchi cosmologies, only a subset of which have ever been tested against data. For the first time, we consider all degrees of freedom in these solutions to conduct a general test of isotropy using cosmic microwave background temperature and polarization data from Planck. For the vector mode (associated with vorticity), we obtain a limit on the anisotropic expansion of (σ_{V}/H)_{0}Universe is strongly disfavored, with odds of 121 000:1 against.
Holographic Metals and Insulators with Helical Symmetry
Donos, Aristomenis; Kiritsis, Elias
2014-01-01
Homogeneous, zero temperature scaling solutions with Bianchi VII spatial geometry are constructed in Einstein-Maxwell-Dilaton theory. They correspond to quantum critical saddle points with helical symmetry at finite density. Assuming $AdS_{5}$ UV asymptotics, the small frequency/(temperature) dependence of the AC/(DC) electric conductivity along the director of the helix are computed. A large class of insulating and conducting anisotropic phases is found, as well as isotropic, metallic phases. Conduction can be dominated by dissipation due to weak breaking of translation symmetry or by a quantum critical current.
The Influence of the Shear on the Gravitational Waves in the Early Anisotropic Universe
Song, Yoogeun
2016-01-01
We study the singularity of the congruences for both timelike and null geodesic curves using the expansion of the early anisotropic Bianchi type I Universe. In this paper, we concentrate on the influence of the shear of the timelike and null geodesic congruences in the early Universe. Under some natural conditions, we derive the Raychaudhuri type equation for the expansion and the shear-related equations. Recently, scientists working on the LIGO (Laser Interferometer Gravitational-Wave Observatory) have shown many possibilities to observing the anisotropy of the primordial gravitational wave background radiation. We deduce the evolution equation for the shear that may be responsible for those observational results.
Ryan, M.
1972-01-01
The study of cosmological models by means of equations of motion in Hamiltonian form is considered. Hamiltonian methods applied to gravity seem to go back to Rosenfeld (1930), who constructed a quantum-mechanical Hamiltonian for linearized general relativity theory. The first to notice that cosmologies provided a simple model in which to demonstrate features of Hamiltonian formulation was DeWitt (1967). Applications of the ADM formalism to homogeneous cosmologies are discussed together with applications of the Hamiltonian formulation, giving attention also to Bianchi-type universes. Problems involving the concept of superspace and techniques of quantization are investigated.
Spinning fluids in general relativity
Ray, J. R.; Smalley, L. L.
1982-01-01
General relativity field equations are employed to examine a continuous medium with internal spin. A variational principle formerly applied in the special relativity case is extended to the general relativity case, using a tetrad to express the spin density and the four-velocity of the fluid. An energy-momentum tensor is subsequently defined for a spinning fluid. The equations of motion of the fluid are suggested to be useful in analytical studies of galaxies, for anisotropic Bianchi universes, and for turbulent eddies.
Unitary evolution for a quantum Kantowski-Sachs cosmology
Pal, Sridip
2015-01-01
It is shown that like Bianchi I, V and IX models, a Kantowski-Sachs cosmological model also allows a unitary evolution on quantization. It has also been shown that this unitarity is not at the expense of the anisotropy. Non-unitarity, if there is any, cannot escape notice in this as the evolution is studied against a properly oriented time parameter fixed by the evolution of the fluid. Furthermore, we have constructed a wave-packet by superposing different energy eigenstates, thereby establishing unitarity in a non-trivial way, which is a stronger result than an energy eigenstate trivially giving time independent probability density. For $\\alpha\
Einstein Geometrization Philosophy and Differential Identities in PAP-Geometry
Wanas, M I; Hanafy, H El; Osman, S N
2016-01-01
The importance of Einstein's geometrization philosophy, as an alternative to the least action principle, in constructing general relativity (GR), is illuminated. The role of differential identities in this philosophy is clarified. The use of Bianchi identity to write the field equations of GR is shown. Another similar identity in the absolute parallelism geometry is given. A more general differential identity in the parameterized absolute parallelism geometry is derived. Comparison and interrelationships between the above mentioned identities and their role in constructing field theories are discussed.
Energy Technology Data Exchange (ETDEWEB)
Chau, L.L.
1983-01-01
Integrable properties, i.e., existence of linear systems, infinite number of conservation laws, Reimann-Hilbert transforms, affine Lie algebra of Kac-Moody, and Bianchi-Baecklund transformation, are discussed for the constraint equations of the supersymmetric Yang-Mills fields. For N greater than or equal to 3 these constraint equations give equations of motion of the fields. These equations of motion reduce to the ordinary Yang-Mills equations as the spinor and scalar fields are eliminated. These understandings provide a possible method to solve the full Yang-Mills equations. Connections with other non-linear systems are also discussed. 53 references.
Towards the entropy of gravity time-dependent models via the Cardy-Verlinde formula
Obregón, O; Quevedo, H; Obregon, Octavio; Patino, Leonardo; Quevedo, Hernando
2003-01-01
For models with several time-dependent components generalized entropies can be defined. This is shown for the Bianchi type IX model. We first derive the Cardy-Verlinde formula under the assumption that the first law of thermodynamics is valid. This leads to an explicit expression of the total entropy associated with this type of universes. Assuming the validity of the Cardy entropy formula, we obtain expressions for the corresponding Bekenstein, Bekenstein-Hawking and Hubble entropies. We discuss the validity of the Cardy-Verlinde formula and possible extensions of the outlined procedure to other time-dependent models.
Moduli of $G_2$ structures and the Strominger system in dimension 7
Clarke, Andrew; Tipler, Carl
2016-01-01
We consider $G_2$ structures with torsion coupled with $G_2$-instantons, on a compact $7$-dimensional manifold. The coupling is via an equation for $4$-forms which appears in supergravity and generalized geometry, known as the Bianchi identity. The resulting system of partial differential equations can be regarded as an analogue of the Strominger system in $7$-dimensions. We initiate the study of the moduli space of solutions and show that it is finite dimensional using elliptic operator theory. We also relate the associated geometric structures to generalized geometry.
Directory of Open Access Journals (Sweden)
Imbruglia, Girolamo
2007-06-01
Full Text Available Proceedings of a 2006 colloquium in Florence on the problem of circulation of ideas in modern Europe through translations mainly in the field of philosophy, science, political thought. Authors and works dealt with: Leonardo Bruni, Theodor Bibliander, De Vigenère, George Buchanan, La Mothe le Vayer, Locke, Lazzaro Spallanzani, Charles Bonnet, Niccolò Pagliarini, William Robertson. Contributions by: G. Imbruglia, R. Minuti, L. Simonutti, C. Le Blanc, L. Felici, R. Mazzei, C. Secretan, L. Bianchi, A. Thomson, G. Cipariani, N. Guasti, L. Kontler
Energy Technology Data Exchange (ETDEWEB)
Montesinos, M. [CINVESTAV-IPN, 07360 Mexico D.F. (Mexico); Flores, E. [Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)]. E-mail: merced@fis.cinvestav.mx
2006-07-01
The symmetric and gauge-invariant energy-momentum tensors for source-free Maxwell and Yang-Mills theories are obtained by means of translations in spacetime via a systematic implementation of Noether's theorem. For the source-free neutral Proca field, the same procedure yields also the symmetric energy-momentum tensor. In all cases, the key point to get the right expressions for the energy-momentum tensors is the appropriate handling of their equations of motion and the Bianchi identities. It must be stressed that these results are obtained without using Belinfante's symmetrization techniques which are usually employed to this end. (Author)
A deep-sea bacterium with unique nitrifying property
Digital Repository Service at National Institute of Oceanography (India)
Ram, A.; LokaBharathi, P.A.; Nair, S.; Chandramohan, D.
s tributed in the marine environment, the number of nitrif i ers mediating this process has rarely been deter - mined. N i trification is generally carried out by known nitrifiers which either oxidize ammonia to nit rite (Phase I) or nitrite to nitrate... assay (chemical assay). Bianchi et al . 10 had shown that the a c tivity determined by chemical assay was comparable to 15 N method. For the present study we used only the chemical assay. The activity in terms of ammonia and nitrite conversion...
Acausality and Non-Unique Evolution in Generalized Teleparallel Gravity
Izumi, Keisuke; Ong, Yen Chin
2013-01-01
We show the existence of physical superluminal modes and acausality in the Brans-Dicke type extension of teleparallel gravity that includes F(T) gravity and teleparallel dark energy as special cases. We derive the characteristic hypersurface for the extra degrees of freedom in the theory, thereby showing that the time evolution is not unique and closed causal curves can appear. Furthermore, we present a concrete disastrous solution in Bianchi type-I spacetime, in which the anisotropy in expansion can be any function of time and thus anisotropy can emerge suddenly, a simple demonstration that the theory is physically problematic.
New torsion black hole solutions in Poincaré gauge theory
Cembranos, Jose A. R.; Gigante Valcarcel, Jorge
2017-01-01
We derive a new exact static and spherically symmetric vacuum solution in the framework of the Poincaré gauge field theory with dynamical massless torsion. This theory is built in such a form that allows to recover General Relativity when the first Bianchi identity of the model is fulfilled by the total curvature. The solution shows a Reissner-Nordström type geometry with a Coulomb-like curvature provided by the torsion field. It is also shown the existence of a generalized Reissner-Nordström-de Sitter solution when additional electromagnetic fields and/or a cosmological constant are coupled to gravity.
Stability analysis of cosmological models through Liapunov's method
Charters, T C; Mimoso, J P; Charters, Tiago C.; Mimoso, Jose P.
2001-01-01
We investigate the general asymptotic behaviour of Friedman-Robertson-Walker (FRW) models with an inflaton field, scalar-tensor FRW cosmological models and diagonal Bianchi-IX models by means of Liapunov's method. This method provides information not only about the asymptotic stability of a given equilibrium point but also about its basin of attraction. This cannot be obtained by the usual methods found in the literature, such as linear stability analysis or first order perturbation techniques. Moreover, Liapunov's method is also applicable to non-autonomous systems. We use this advantadge to investigate the mechanism of reheating for the inflaton field in FRW models.
Smooth Quantum Dynamics of Mixmaster Universe
Bergeron, Hervé; Gazeau, Jean Pierre; Małkiewicz, Przemysław; Piechocki, Włodzimierz
2015-01-01
We present a quantum version of the vacuum Bianchi IX model by implementing affine coherent state quantization combined with a Born-Oppenheimer-like adiabatic approximation. The analytical treatment is carried out on both quantum and semiclassical levels. The resolution of the classical singularity occurs by means of a repulsive potential generated by our quantization procedure. The quantization of the oscillatory degrees of freedom produces a radiation energy density term in the semiclassical constraint equation. The Friedmann-like lowest energy eigenstates of the system are found to be dynamically stable.
Supersymmetry and non-Abelian T-duality in type II supergravity
Kelekci, Özgür; Macpherson, Niall T; Colgáin, Eoin Ó
2014-01-01
We study the effect of T-duality on supersymmetry in the context of type II supergravity. For both U(1) Abelian and SU(2) non-Abelian T-duality, we demonstrate that the Killing spinor equations before and after T-duality can be mapped up to the Kosmann spinorial Lie derivative, which guarantees supersymmetry is preserved upon vanishing. As a byproduct, we give closed expressions for SU(2) T-duality in a class of spacetimes with diagonal Bianchi IX symmetry and comment on specific examples of T-dual geometries, including a novel AdS3 geometry with large N = (4,4) superconformal symmetry.
,
2016-01-01
With Einstein's inertial motion (free-falling and non-rotating relative to gyroscopes), geodesics for non-relativistic particles can intersect repeatedly, allowing one to compute the space-time curvature $R^{\\hat{0} \\hat{0}}$ exactly. Einstein's $R^{\\hat{0} \\hat{0}}$ for strong gravitational fields and for relativistic source-matter is identical with the Newtonian expression for the relative radial acceleration of neighboring free-falling test-particles, spherically averaged.--- Einstein's field equations follow from Newtonian experiments, local Lorentz-covariance, and energy-momentum conservation combined with the Bianchi identity.
Anisotropic exact solutions in scalar-tensor-vector gravity
Sharif, M.; Yousaf, Aasma
2016-09-01
The aim of this paper is to explore exact solutions in the scalar-tensor-vector theory of gravity with two scalar fields and one vector field. We consider a locally rotationally symmetric Bianchi type-I universe filled with perfect fluid. The first exact solution is found through certain assumptions while the second solution is obtained through Noether symmetry approach. We discuss the behavior of the resulting solutions numerically and also explore the corresponding energy conditions. It is found that the strong energy condition is violated in both cases indicating the accelerated expansion of the universe.
Some exact anisotropic solutions via Noether symmetry in f(R) gravity
Energy Technology Data Exchange (ETDEWEB)
Sharif, M., E-mail: msharif.math@pu.edu.pk; Nawazish, I., E-mail: iqranawazish07@gmail.com [University of the Punjab, Department of Mathematics (Pakistan)
2015-01-15
We attempt to find exact solutions of the Bianchi I model in f(R) gravity using the Noether symmetry approach. For this purpose, we take a perfect fluid and formulate conserved quantities for the power-law f(R) model. We discuss some cosmological parameters for the resulting solution which are responsible for expanding behavior of the universe. We also explore Noether gauge symmetry and the corresponding conserved quantity. It is concluded that symmetry generators as well as conserved quantities exist in all cases and the behavior of cosmological parameters shows consistency with recent observational data.
Shear-free condition and dynamical instability in f(R, T) gravity
Energy Technology Data Exchange (ETDEWEB)
Noureen, Ifra; Bhatti, A.A. [University of Management and Technology, Department of Mathematics, SST, Lahore (Pakistan); Zubair, M. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan); Abbas, G. [COMSATS Institute of Information Technology, Department of Mathematics, Sahiwal (Pakistan)
2015-07-15
The implications of the shear-free condition on the instability range of an anisotropic fluid in f(R, T) are studied in this manuscript. A viable f(R, T) model is chosen to arrive at stability criterion, where R is Ricci scalar and T is the trace of energy-momentum tensor. The evolution of a spherical star is explored by employing a perturbation scheme on the modified field equations and contracted Bianchi identities in f(R, T). The effect of the imposed shear-free condition on the collapse equation and adiabatic index Γ is studied in the Newtonian and post-Newtonian regimes. (orig.)
Cohomology with causally restricted supports
Khavkine, Igor
2014-01-01
De Rham cohomology with spacelike compact and timelike compact supports has recently been noticed to be of importance for understanding the structure of classical and quantum field theories on curved spacetimes. We compute these cohomology groups for globally hyperbolic spacetimes in terms of their standard de Rham cohomologies. The calculation exploits the fact that the de Rham-d'Alambert wave operator can be extended to a chain map that is homotopic to zero and that its causal Green function fits into a convenient exact sequence. This method extends also to the Calabi (or Killing-Riemann-Bianchi) complex and possibly other differential complexes. We also discuss generalized causal structures and functoriality.
Instabilities in numerical loop quantum cosmology
Rosen, J; Khanna, G; Jung, Jae-Hun; Khanna, Gaurav; Rosen, Jessica
2006-01-01
In this article we perform von Neumann analysis of the difference equations that arise as a result of loop quantum gravity being applied to models of cosmology and black holes. In particular, we study the numerical stability of Bianchi I LRS (symmetric and non-symmetric constraint) and Schwarzschild interior (symmetric constraint) models, and find that there exist domains over which there are instabilities, generically. We also present explicit evolutions of wave-packets in these models and clearly demonstrate the presence of these instabilities.
Radiative corrections to the EPRL-FK spinfoam graviton
Riello, Aldo
2013-01-01
I study the corrections engendered by the insertion of a "melon" graph in the bulk of the first-order spinfoam used for the graviton propagator. I find that these corrections are highly non-trivial and, in particular, that they concern those terms which disappear in the Bojowald-Bianchi-Magliaro-Perini limit of vanishing Barbero-Immirzi parameter at fixed area. This fact is the first realization of the often cited idea that the spinfoam amplitude receives higher order corrections under the refinement of the underlying two-complex.
Moller Energy-Momentum Prescription for a Locally Rotationally Symmetric Space-Time
Aydogdu, O
2006-01-01
The energy distribution in the Locally Rotationally Symmetric (LRS) Bianchi type II space-time is obtained by considering the Moller energy-momentum definition in both Einstein's theory of general relativity and teleparallel theory of relativity. The energy distribution which includes both the matter and gravitational field is found to be zero in both of these different gravitation theories. This result agrees with previous works of Cooperstock and Israelit, Rosen, Johri et al., Banerjee and Sen, Vargas, and Aydogdu and Salti. Our result that the total energy of the universe is zero supports the view points of Albrow and Tryon.
Inflationary Weak Anisotropic Model with General Dissipation Coefficient
Sharif, M
2015-01-01
This paper explores the dynamics of warm intermediate and logamediate inflationary models during weak dissipative regime with a general form of dissipative coefficient. We analyze these models within the framework of locally rotationally symmetric Bianchi type I universe. In both cases, we evaluate solution of inflaton, effective scalar potential, dissipative coefficient, slow-roll parameters, scalar and tensor power spectra, scalar spectral index and tensor to scalar ratio under slow-roll approximation. We constrain the model parameters using recent data and conclude that anisotropic inflationary universe model with generalized dissipation coefficient remains compatible with WMAP9, Planck and BICEP2 data.
A note on the architecture of spacetime geometry
Zuo, Fen
2016-01-01
Recently the $SU(2)$ spin-network states in loop quantum gravity is generalized to those of the corresponding Kac-Moody algebra. We show that if one literally starts from the full $SL(2,\\mathcal{C})$ group, this procedure naturally leads to the Bekenstein-Hawking formula of the entanglement entropy for any macroscopic spacetime region. This suggests that a smooth spacetime geometry could be recovered in such a way, as conjectured by Bianchi and Myers. Some comparison with Xiao-Gang Wen's string-net picture of gauge theory is made.
Bose Fermi Supersymmetry with Bogoliubov transforms in Cosmology
Patwardhan, A
2006-01-01
Field theory including Supersymmetry and Bose Fermi Symmetry is an active subject of particle physics and cosmology. Recent and expected observational evidence gives indicators for the creation and destruction of normal and supersymmetric dark matter in the universe. This paper uses Bogoliubov transforms in supersymmetric and Bose Fermi form for obtaining the vaccuum expectation values at any two times in cosmological and black hole geometries. The isotropic Robertson Walker and slightly anisotropic Bianchi I geometry mode functions have a differential equation form analogous to the supersymmetric Hamiltonian. The condition for mixed and distinct representations for bosonic and fermionic fields of normal and supersymmetric partner particles are found.
Inevitable inflation in Einstein-Cartan theory with improved energy-momentum tensor with spin
Fennelly, A. J.; Bradas, James C.; Smalley, Larry L.
Generalized, or power-law, inflation is shown to necessarily exist for a simple, anisotropic, (Bianchi Type-1) cosmology in the Einstein-Cartan gravitational theory with the Ray-Smalley improved energy momentum tensor with spin. Formal solution of the EC field equations with the fluid equations of motion explicitly shows inflation caused by the RS spin angular kinetic energy density. Shear is not effective in preventing inflation in the ECRS model. The relation between fluid vorticity, torsion, reference axis rotation, and shear ellipsoid precession shows through clearly.