1,062 research outputs found

    Effective dynamics of the closed loop quantum cosmology

    Full text link
    In this paper we study dynamics of the closed FRW model with holonomy corrections coming from loop quantum cosmology. We consider models with a scalar field and cosmological constant. In case of the models with cosmological constant and free scalar field, dynamics reduce to 2D system and analysis of solutions simplify. If only free scalar field is included then universe undergoes non-singular oscillations. For the model with cosmological constant, different behaviours are obtained depending on the value of Λ\Lambda. If the value of Λ\Lambda is sufficiently small, bouncing solutions with asymptotic de Sitter stages are obtained. However if the value of Λ\Lambda exceeds critical value Λc=3mPl22πγ321mPl2\Lambda_{\text{c}} =\frac{\sqrt{3}m^2_{\text{Pl}}}{2\pi\gamma^3} \simeq 21 m^2_{\text{Pl}} then solutions become oscillatory. Subsequently we study models with a massive scalar field. We find that this model possess generic inflationary attractors. In particular field, initially situated in the bottom of the potential, is driven up during the phase of quantum bounce. This subsequently leads to the phase of inflation. Finally we find that, comparing with the flat case, effects of curvature do not change qualitatively dynamics close to the phase of bounce. Possible effects of inverse volume corrections are also briefly discussed.Comment: 18 pages, 11 figure

    Eber und Börge im Vergleich – Auswirkungen der Kastration auf agonistisches und sexuell motiviertes Verhalten unter ökologischen Haltungsbedingungen

    Get PDF
    Nach dem Verbot der betäubungslosen Ferkelkastration nach VO (EG) 889 (2008) zum 01.01.2012 stellt die Ebermast eine mögliche Alternative für die ökologische Schweinefleischerzeugung dar. Im Rahmen des Projektes „Ebermast im Verbund: Entwicklung eines Konzepts für die Produktion, Schlachtung, Verarbeitung und Vermarktung ökologisch erzeugter Eber entlang der Wertschöpfungskette“ ist es ein Ziel, das Ausmaß möglichen unerwünschten Verhaltens, wie agonistische Interaktionen und Aufreitverhalten der Eber, mit dem von Börgen unter praxisüblichen ökologischen Haltungsbedingungen zu vergleichen und wichtige Einflussfaktoren hierauf zu identifizieren. Auch mögliche Verletzungsfolgen sollen einbezogen werden. Aus einer Zwischenauswertung werden hier erste Ergebnisse zum Ausmaß des genannten Verhaltens und der Verletzungsfolgen vorgestellt. 9 Gruppen Eber und 7 Gruppen Börge wurden mit einem Lebendgewicht von etwa 80 kg auf vier ökologischen Praxisbetrieben beobachtet. Agonistische Interaktionen (Kopfschlagen, Beißen, Kampf und Besteigen ohne sexuelle Motivation) und Besteigen mit sexueller Motivation wurden mittels kontinuierlicher Verhaltenszählung (continuous behaviour sampling) jeweils über die ersten 15 Minuten einer jeden Lichtstunde von zusammenhängenden 48h-Aufnahmen ausgewertet. Zum selben Zeitpunkt wurden zusätzlich die Verletzungen bei den 109 Ebern und 91 Börgen gezählt. Eber zeigten bezüglich aller erhobener Verhaltensparameter gegenüber den Börgen signifikant höhere Häufigkeiten bzw. Dauern. Dagegen konnten hinsichtlich der Verletzungsscores zwischen Ebern und Börgen keine signifikanten Unterschiede festgestellt werden. Die Untersuchung wird fortgesetzt

    Optimal Gersgorin-Style Estimation Of The Largest Singular Value, Ii

    Get PDF
    In estimating the largest singular value in the class of matrices equiradial with a given n-by-n complex matrix A, it was proved that it is attained at one of n(n - 1) sparse nonnegative matrices (see C.R. Johnson, J.M. Penna and T. Szulc, Optimal Gersgorin-style estimation of the largest singular value; Electronic Journal of Linear Algebra Algebra Appl., 25: 48-59, 2011). Next, some circumstances were identified under which the set of possible optimizers of the largest singular value can be further narrowed (see C.R. Johnson, T. Szulc and D. Wojtera-Tyrakowska, Optimal Gersgorin-style estimation of the largest singular value, Electronic Journal of Linear Algebra Algebra Appl., 25: 48-59, 2011). Here the cardinality of the mentioned set for n-by-n matrices is further reduced. It is shown that the largest singular value, in the class of matrices equiradial with a given n-by-n complex matrix, is attained at one of n (n - 1) /2 sparse nonnegative matrices. Finally, an inequality between the spectral radius of a 3-by-3 nonnegative matrix X and the spectral radius of a modification of X is also proposed

    The status of Quantum Geometry in the dynamical sector of Loop Quantum Cosmology

    Full text link
    This letter is motivated by the recent papers by Dittrich and Thiemann and, respectively, by Rovelli discussing the status of Quantum Geometry in the dynamical sector of Loop Quantum Gravity. Since the papers consider model examples, we also study the issue in the case of an example, namely on the Loop Quantum Cosmology model of space-isotropic universe. We derive the Rovelli-Thiemann-Ditrich partial observables corresponding to the quantum geometry operators of LQC in both Hilbert spaces: the kinematical one and, respectively, the physical Hilbert space of solutions to the quantum constraints. We find, that Quantum Geometry can be used to characterize the physical solutions, and the operators of quantum geometry preserve many of their kinematical properties.Comment: Latex, 12 page

    Secondary Osteoporosis: Endocrine and Metabolic Causes of Bone Mass Deterioration

    Get PDF
    License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Secondary osteoporosis results from medical conditions or treatments that interfere with the attainment of peak bone mass and/or may predispose to accelerated bone loss. Although secondary osteoporosis is less common, it is becoming more frequently diagnosed. Apart from the welldefined risk of secondary osteoporosis in patients requiring long-term corticosteroids therapy, an increasing list of dietary, lifestyle, endocrine, metabolic, and other causes of bone mass deterioration has been identified (Table 1). Recently it has been demonstrated that, in contrast to primary osteoporosis which is associated with age, gender, and family history, secondary osteoporosis shows a prevalence in men similar to that in women (men 21 % versus women 17.5%

    Non-singular Universes a la Palatini

    Get PDF
    It has recently been shown that f(R) theories formulated in the Palatini variational formalism are able to avoid the big bang singularity yielding instead a bouncing solution. The mechanism responsible for this behavior is similar to that observed in the effective dynamics of loop quantum cosmology and an f(R) theory exactly reproducing that dynamics has been found. I will show here that considering more general actions, with quadratic contributions of the Ricci tensor, results in a much richer phenomenology that yields bouncing solutions even in anisotropic (Bianchi I) scenarios. Some implications of these results are discussed.Comment: 4 pages, no figures. Contribution to the Spanish Relativity Meeting (ERE2010), 6-10 Sept. Granada, Spai

    Numerical calculations of effective elastic properties of two cellular structures

    Full text link
    Young's moduli of regular two-dimensional truss-like and eye-shape-like structures are simulated by using the finite element method. The structures are the idealizations of soft polymeric materials used in the electret applications. In the simulations size of the representative smallest units are varied, which changes the dimensions of the cell-walls in the structures. A power-law expression with a quadratic as the exponential term is proposed for the effective Young's moduli of the systems as a function of the solid volume fraction. The data is divided into three regions with respect to the volume fraction; low, intermediate and high concentrations. The parameters of the proposed power-law expression in each region are later represented as a function of the structural parameters, unit-cell dimensions. The presented expression can be used to predict structure/property relationship in materials with similar cellular structures. It is observed that the structures with volume fractions of solid higher than 0.15 exhibit the importance of the cell-wall thickness contribution in the elastic properties. The cell-wall thickness is the most significant factor to predict the effective Young's modulus of regular cellular structures at high volume fractions of solid. At lower concentrations of solid, eye-like structure yields lower Young's modulus than the truss-like structure with the similar anisotropy. Comparison of the numerical results with those of experimental data of poly(propylene) show good aggreement regarding the influence of cell-wall thickness on elastic properties of thin cellular films.Comment: 7 figures and 2 table

    Closed FRW model in Loop Quantum Cosmology

    Get PDF
    The basic idea of the LQC applies to every spatially homogeneous cosmological model, however only the spatially flat (so called k=0k=0) case has been understood in detail in the literature thus far. In the closed (so called: k=1) case certain technical difficulties have been the obstacle that stopped the development. In this work the difficulties are overcome, and a new LQC model of the spatially closed, homogeneous, isotropic universe is constructed. The topology of the spacelike section of the universe is assumed to be that of SU(2) or SO(3). Surprisingly, according to the results achieved in this work, the two cases can be distinguished from each other just by the local properties of the quantum geometry of the universe. The quantum hamiltonian operator of the gravitational field takes the form of a difference operator, where the elementary step is the quantum of the 3-volume derived in the flat case by Ashtekar, Pawlowski and Singh. The mathematical properties of the operator are studied: it is essentially self-adjoint, bounded from above by 0, the 0 itself is not an eigenvalue, the eigenvectors form a basis. An estimate on the dimension of the spectral projection on any finite interval is provided.Comment: 19 pages, latex, no figures, high quality, nea

    EPI-001, A Compound Active against Castration-Resistant Prostate Cancer, Targets Transactivation Unit 5 of the Androgen Receptor

    Get PDF
    ACKNOWLEDGEMENTS We thank J. M. Valverde (IRB) as well as the NMR facilities of the University of Barcelona (CCiT UB) and the Instituto de Química Física Rocasolano (IQFR, CSIC) for their assistance in, respectively, protein production and NMR. This work was supported by IRB, ICREA (X.S.), Obra Social “la Caixa” (Fellowship to E.D.M. and CancerTec grants to X.S.) MICINN (CTQ2009-08850 to X.S.), MINECO (BIO2012-31043 to X.S.; CTQ2014-56361-P to A.R), Marató de TV3 (102030 to X.S. and 102031 to E.E.P) the COFUND programme of the European Commission (C.T.W.P., A. R. and X.S.), the European Research Council (CONCERT, contract number 648201, to X.S.), the Ramón y Cajal program of MICINN (RYC-2011-07873 to C.W.B.) the Serra Hunter Programme (E.E.P.) and AGAUR (SGR-2014-56RR14 to E.E.P). IRB Barcelona is the recipient of a Severo Ochoa Award of Excellence from MINECO (Government of Spain)Peer reviewedPostprin
    corecore