47 research outputs found

    Bose-Einstein condensation and condensation of qq-particles in equilibrium and non equilibrium thermodynamics: a new approach

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    In the setting of the principle of local equilibrium which asserts that the temperature is a function of the energy levels of the system, we exhibit plenty of steady states describing the condensation of free Bosons which are not in thermal equilibrium. The surprising facts are that the condensation can occur both in dimension less than 3 in configuration space, and even in excited energy levels. The investigation relative to non equilibrium suggests a new approach to the condensation, which allows an unified analysis involving also the condensation of qq-particles, −1≀q≀1-1\leq q\leq 1, where q=±1q=\pm1 corresponds to the Bose/Fermi alternative. For such qq-particles, the condensation can occur only if 0<q≀10<q\leq1, the case 1 corresponding to the standard Bose-Einstein condensation. In this more general approach, completely new and unexpected states exhibiting condensation phenomena naturally occur also in the usual situation of equilibrium thermodynamics. The new approach proposed in the present paper for the situation of 2nd2^\text{nd} quantisation of free particles, is naturally based on the theory of the Distributions, which might hopefully be extended to more general casesComment: It is a preprint of July 201

    Entangled Markov chains

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    Motivated by the problem of finding a satisfactory quantum generalization of the classical random walks, we construct a new class of quantum Markov chains which are at the same time purely generated and uniquely determined by a corresponding classical Markov chain. We argue that this construction yields as a corollary, a solution to the problem of constructing quantum analogues of classical random walks which are "entangled" in a sense specified in the paper. The formula giving the joint correlations of these quantum chains is obtained from the corresponding classical formula by replacing the usual matrix multiplication by Schur multiplication. The connection between Schur multiplication and entanglement is clarified by showing that these quantum chains are the limits of vector states whose amplitudes, in a given basis (e.g. the computational basis of quantum information), are complex square roots of the joint probabilities of the corresponding classical chains. In particular, when restricted to the projectors on this basis, the quantum chain reduces to the classical one. In this sense we speak of entangled lifting, to the quantum case, of a classical Markov chain. Since random walks are particular Markov chains, our general construction also gives a solution to the problem that motivated our study. In view of possible applications to quantum statistical mechanics too, we prove that the ergodic type of an entangled Markov chain with finite state space (thus excluding random walks) is completely determined by the corresponding ergodic type of the underlying classical chain

    Transverse Momentum Broadening and the Jet Quenching Parameter, Redux

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    We use Soft Collinear Effective Theory (SCET) to analyze the transverse momentum broadening, or diffusion in transverse momentum space, of an energetic parton propagating through quark-gluon plasma. Since we neglect the radiation of gluons from the energetic parton, we can only discuss momentum broadening, not parton energy loss. The interaction responsible for momentum broadening in the absence of radiation is that between the energetic (collinear) parton and the Glauber modes of the gluon fields in the medium. We derive the effective Lagrangian for this interaction, and we show that the probability for picking up transverse momentum k_\perp is given by the Fourier transform of the expectation value of two transversely separated light-like path-ordered Wilson lines. This yields a field theoretical definition of the jet quenching parameter \hat q, and shows that this can be interpreted as a diffusion constant. We close by revisiting the calculation of \hat q for the strongly coupled plasma of N=4 SYM theory, showing that previous calculations need some modifications that make them more straightforward and do not change the result.Comment: 18 pages, 7 figures; v2, minor revisions, references added; v3, version to appear in Phys. Rev. D: Feynman rules corrected, improved explanations of the gauge invariance of our calculation and of how the scaling of SCET operators differs from that in other contexts in the literature; no changes to any result

    Strict weak mixing of some C*-dynamical systems based on free shifts

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    We define a stronger property than unique ergodicity with respect to the fixed-point subalgebra previously investigated by Abadie and Dykema. Such a property is denoted as F-strict weak mixing (F stands for the Markov projection onto the fixed-point operator system). Then we show that the free shifts on the reduced C*-algebras of RD-groups, including the free group on infinitely many generators, and amalgamated free product C*-algebras, considered by Abadie and Dykema, are all strictly weak mixing and not merely uniquely ergodic.Comment: 10 page

    De Finetti theorem on the CAR algebra

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    The symmetric states on a quasi local C*-algebra on the infinite set of indices J are those invariant under the action of the group of the permutations moving only a finite, but arbitrary, number of elements of J. The celebrated De Finetti Theorem describes the structure of the symmetric states (i.e. exchangeable probability measures) in classical probability. In the present paper we extend De Finetti Theorem to the case of the CAR algebra, that is for physical systems describing Fermions. Namely, after showing that a symmetric state is automatically even under the natural action of the parity automorphism, we prove that the compact convex set of such states is a Choquet simplex, whose extremal (i.e. ergodic w.r.t. the action of the group of permutations previously described) are precisely the product states in the sense of Araki-Moriya. In order to do that, we also prove some ergodic properties naturally enjoyed by the symmetric states which have a self--containing interest.Comment: 23 pages, juornal reference: Communications in Mathematical Physics, to appea

    The Critical Exponents Of The Matrix Valued Gross-Neveu Model

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    We study the large N limit of the MATRIX valued Gross-Neveu model in 2<d<4 dimensions. The method employed is a combination of the approximate recursion formula of Polyakov and Wilson with the solution to the zero dimensional large N counting problem of Makeenko and Zarembo. The model is found to have a phase transition at a finite value for the critical temperature and the critical exponents are approximated by nu = 1/(2(d-2)) and eta=d-2. We test the validity of the approximation by applying it to the usual vector models where it is found to yield exact results to leading order in 1/N.Comment: 19 pages, LaTeX.2e + macro epsfig. Two eps figures, four LeTeX picture

    The osteopath-parent-child triad in osteopathic care in the first 2 years of life: a qualitative study

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    BackgroundEnactivism and active inference are two important concepts in the field of osteopathy. While enactivism emphasizes the role of the body and the environment in shaping our experiences and understanding of the world, active inference emphasizes the role of action and perception in shaping our experiences and understanding of the world. Together, these frameworks provide a unique perspective on the practice of osteopathy, and how it can be used to facilitate positive change in patients. Since the neonatal period is a crucial time for development, osteopaths should aim to create a therapeutic relationship. Arguably, through participatory sense-making, osteopaths can help the baby build a generative model (with positive priors) to deal with stress and needs throughout their life.AimSince the literature considers that interactions with the environment, which enact the patients’ experiences, depending on contextual factors and communication between patient and caregiver, this research explored whether there is a correspondence between the indications in the literature and clinical practice in the management of the mother/parent–child dyad during osteopathic care on children aged 0 to 2 years old.MethodsSemi-structured interviews were conducted with a purposive sample of nine osteopaths with experience in the field of pediatrics. Interviews were transcribed verbatim, and constructivist grounded theory was used to conceptualize, collect and analyze data. Codes and categories were actively constructed through an interpretive/constructionist paradigm.ResultsThe core category was the idea of the pediatric osteopath as a support for the family, not only for the child. Four additional categories were identified: (1) Preparing a safe environment for both children and parents, (2) Communication, (3) Attachment and synchrony, and (4) Synchronization.ConclusionThrough participatory sense-making, osteopaths manage contextual factors to establish an effective therapeutic alliance through the osteopath-parent–child triad to facilitate the construction of the child’s internal generative model to promote healthy development. The therapeutic encounter is considered an encounter between embodied subjects, occurring within a field of affordances (ecological niche) that allows the interlocutors to actively participate in creating new meanings through interpersonal synchronization. Participatory sense-making and the establishment of a therapeutic alliance through the osteopath-parent–child triad are crucial to promote healthy development in the child

    Analysis of T and NK cell subsets in Sicilian population from young to supercentenarian: the role of age and gender

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    Ageing dramatically affects number and function of both innate and adaptive arms of immune system, particularly T cell subsets, contributing to reduced vaccination efficacy, decreased resistance to infections and increased prevalence of cancer in the older people. In the present paper, we analysed the age-related changes in the absolute number of lymphocytes in 214 Sicilian subjects, and in the percentages of T and NK cells in a sub-cohort of donors. We compared these results with the immunophenotype of the oldest living Italian supercentenarian (111 years old). The results were also sorted by gender. The correlation between number/percentage of cells and age in all individuals and, separately, in males and females, was examined using a simple linear regression analysis. We did not record the increase in the rate of inversion of the CD4/CD8 ratio frequently reported as associated with ageing in literature. Our observation was the direct consequence of a flat average trend of CD4+ and CD8+ T cell percentages in ageing donors, even when gender differences were included. Our results also suggest that CD4+ and CD8+ subsets are not affected equally by age comparing females with males, and we speculated that gender may affect the response to CMV infection. The supercentenarian showed a unique immunophenotypic signature as regards the relative percentages of her T cell subsets, with CD4+ and CD8+ T cell percentages and CD4+ na\uefve T cell values in line with those recorded for the octogenarian subjects. This suggests that the supercentenarian has a na\uefve "younger" T cell profile comparable to that of a &gt;80 year old female

    Anti-Inflammatory Effects of Nutritionally Relevant Concentrations of Oleuropein and Hydroxytyrosol on Peripheral Blood Mononuclear Cells: An Age-Related Analysis

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    : Immunosenescence and inflammaging facilitate the insurgence of chronic diseases. The Mediterranean diet is a non-invasive intervention to improve the chronic low-grade inflammatory status associated with aging. Olive oil oleuropein (OLE) and hydroxytyrosol (HT) demonstrated a controversial modulatory action on inflammation in vitro when tested at concentrations exceeding those detectable in human plasma. We studied the potential anti-inflammatory effects of OLE and HT at nutritionally relevant concentrations on peripheral blood mononuclear cells (PBMCs) as regards cell viability, frequency of leukocyte subsets, and cytokine release, performing an age-focused analysis on two groups of subjects: Adult (age 18–64 years) and Senior (age ≄ 65 years). OLE and HT were used alone or as a pre-treatment before challenging PBMCs with lipopolysaccharide (LPS). Both polyphenols had no effect on cell viability irrespective of LPS, but 5 ”M HT had an LPS-like effect on monocytes, reducing the intermediate subset in Adult subjects. OLE and HT had no effect on LPS-triggered release of TNF-α, IL-6 and IL-8, but 5 ”M HT reduced IL-10 secretion by PBMCs from Adult vs. Senior group. In summary, nutritionally relevant concentrations of OLE and HT elicit no anti-inflammatory effect and influence the frequency of immune cell subsets with age-related different outcomes
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