4,439 research outputs found

    Enforced neutrality and color-flavor unlocking in the three-flavor Polyakov-loop NJL model

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    We study how the charge neutrality affects the phase structure of three-flavor PNJL model. We point out that, within the conventional PNJL model at finite density the color neutrality is missing because the Wilson line serves as an external ``colored'' field coupled to dynamical quarks. In this paper we heuristically assume that the model may still be applicable. To get color neutrality one has then to allow non vanishing color chemical potentials. We study how the quark matter phase diagram in (T,ms2/μ)(T,m_s^2/\mu)-plane is affected by imposing neutrality and by including the Polyakov loop dynamics. Although these two effects are correlated in a nonlinear way, the impact of the Polyakov loop turns out to be significant in the TT direction, while imposing neutrality brings a remarkable effect in the ms2/μm_s^2/\mu direction. In particular, we find a novel unlocking transition, when the temperature is increased, even in the chiral SU(3) limit. We clarify how and why this is possible once the dynamics of the colored Polyakov loop is taken into account. Also we succeed in giving an analytic expression for TcT_c for the transition from two-flavor pairing (2SC) to unpaired quark matter in the presence of the Polyakov loop.Comment: 11 pages, REVTex4, 10 eps figures; v2: added two notes, added a reference; version to appear in Phys. Rev.

    Superfluid and Pseudo-Goldstone Modes in Three Flavor Crystalline Color Superconductivity

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    We study the bosonic excitations in the favorite cubic three flavor crystalline LOFF phases of QCD. We calculate in the Ginzburg-Landau approximation the masses of the eight pseudo Nambu-Goldstone Bosons (NGB) present in the low energy theory. We also compute the decay constants of the massless NGB Goldstones associated to superfluidity as well as those of the eight pseudo NGB. Differently from the corresponding situation in the Color-Flavor-Locking phase, we find that meson condensation phases are not expected in the present scenario.Comment: 10 pages, RevTeX4 class. Section IIIA enlarged, to appear on Phys. Rev.

    A clinical review on megalencephaly: A large brain as a possible sign of cerebral impairment.

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    Megalencephaly and macrocephaly present with a head circumference measurement 2 standard deviations above the age-related mean. However, even if pathologic events resulting in both megalencephaly and macrocephaly may coexist, a distinction between these two entities is appropriate, as they represent clinical expression of different disorders with a different approach in clinical work-up, overall prognosis, and treatment. Megalencephaly defines an increased growth of cerebral structures related to dysfunctional anomalies during the various steps of brain development in the neuronal proliferation and/or migration phases or as a consequence of postnatal abnormal events. The disorders associated with megalencephaly are classically defined into 3 groups: idiopathic or benign, metabolic, and anatomic. In this article, we seek to underline the clinical aspect of megalencephaly, emphasizing the main disorders that manifest with this anomaly in an attempt to properly categorize these disorders within the megalencephaly group

    Congenital muscular dystrophy: from muscle to brain.

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    Congenital muscular dystrophies (CMDs) are a wide group of muscular disorders that manifest with very early onset of muscular weakness, sometime associated to severe brain involvement.The histologic pattern of muscle anomalies is typical of dystrophic lesions but quite variable depending on the different stages and on the severity of the disorder.Recent classification of CMDs have been reported most of which based on the combination of clinical, biochemical, molecular and genetic findings, but genotype/phenotype correlation are in constant progression due to more diffuse utilization of the molecular analysis.In this article, the Authors report on CMDs belonging to the group of dystroglycanopathies and in particular on the most severe forms represented by the Fukuyama CMD, Muscle-Eye-Brain disease and Walker Walburg syndrome.Clinical diagnosis of infantile hypotonia is particularly difficult considering the different etiologic factors causing the lesions, the difficulty in localizing the involved CNS area (central vs. peripheral) and the limited role of the diagnostic procedures at this early age.The diagnostic evaluation is not easy mainly in differentiating the various types of CMDs, and represents a challenge for the neonatologists and pediatricians. Suggestions are reported on the way to reach a correct diagnosis with the appropriate use of the diagnostic means

    Porting Decision Tree Algorithms to Multicore using FastFlow

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    The whole computer hardware industry embraced multicores. For these machines, the extreme optimisation of sequential algorithms is no longer sufficient to squeeze the real machine power, which can be only exploited via thread-level parallelism. Decision tree algorithms exhibit natural concurrency that makes them suitable to be parallelised. This paper presents an approach for easy-yet-efficient porting of an implementation of the C4.5 algorithm on multicores. The parallel porting requires minimal changes to the original sequential code, and it is able to exploit up to 7X speedup on an Intel dual-quad core machine.Comment: 18 pages + cove

    On the ground state of gapless two flavor color superconductors

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    This paper is devoted to the study of some aspects of the instability of two flavor color superconductive quark matter. We find that, beside color condensates, the Goldstone boson related to the breaking of U(1)AU(1)_A suffers of a velocity instability. We relate this wrong sign problem, which implies the existence of a Goldstone current in the ground state or of gluonic condensation, to the negative squared Meissner mass of the 8th8^{th} gluon in the g2SC phase. Moreover we investigate the Meissner masses of the gluons and the squared velocity of the Goldstone in the multiple plane wave LOFF states, arguing that in such phases both the chromo-magnetic instability and the velocity instability are most probably removed. We also do not expect Higgs instability in such multiple plane wave LOFF. The true vacuum of gapless two flavor superconductors is thus expected to be a multiple plane wave LOFF state.Comment: 16 pages, RevTe3X4 styl
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