47 research outputs found
Bose-Einstein condensation and condensation of -particles in equilibrium and non equilibrium thermodynamics: a new approach
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 -particles, , where corresponds
to the Bose/Fermi alternative. For such -particles, the condensation can
occur only if , 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 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
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
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
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
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
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 2âyears of life: a qualitative study
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 patientsâ 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/parentâchild dyad during osteopathic care on children aged 0 to 2âyears 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-parentâchild triad to facilitate the construction of the childâs 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-parentâchild 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
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 >80 year old female
Anti-Inflammatory Effects of Nutritionally Relevant Concentrations of Oleuropein and Hydroxytyrosol on Peripheral Blood Mononuclear Cells: An Age-Related Analysis
: 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 18â64 years) and Senior (age â„ 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