422 research outputs found

    Equilibrium Statistical Mechanics of Fermion Lattice Systems

    Full text link
    We study equilibrium statistical mechanics of Fermion lattice systems which require a different treatment compared with spin lattice systems due to the non-commutativity of local algebras for disjoint regions. Our major result is the equivalence of the KMS condition and the variational principle with a minimal assumption for the dynamics and without any explicit assumption on the potential. It holds also for spin lattice systems as well, yielding a vast improvement over known results. All formulations are in terms of a C*-dynamical systems for the Fermion (CAR) algebra with all or a part of the following assumptions: (I) The interaction is even with respect to the Fermion number. (Automatically satisfied when (IV) below is assumed.) (II) All strictly local elements of the algebra have the first time derivative. (III) The time derivatives in (II) determine the dynamics. (IV) The interaction is lattice translation invariant. A major technical tool is the conditional expectation from the total algebra onto the local subalgebra for any finite subset of the lattice, which induces a system of commuting squares. This technique overcomes the lack of tensor product structures for Fermion systems and even simplifies many known arguments for spin lattice systems.Comment: 103 pages, no figure. The Section 13 has become simpler and a problem in 14.1 is settled thanks to a referee. The format has been revised according to the suggestion of this and the other referee

    Salmonella enterica Typhimurium FljBA operon Sstability: implications regarding the origin of Salmonella enterica I 4,[5],12:i:-

    Get PDF
    FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORSalmonella enterica subsp enterica serovar 4,5,12:i:- has been responsible for many recent Salmonella outbreaks worldwide. Several studies indicate that this serovar originated from S. enterica subsp enterica serovar Typhimurium, by the loss of the flagellar phase II gene (fljB) and adjacent sequences. However, at least two different clones of S. enterica 4,5,12:i:- exist that differs in the molecular events responsible for fljB deletion. The aim of this study was to test the stability of the fljBA operon responsible for the flagellar phase variation under different growth conditions in order to verify if its deletion is a frequent event that could explain the origin and dissemination of this serovar. In fact, coding sequences for transposons are present near this operon and in some strains, such as S. enterica Typhimurium LT2, the Fels-2 prophage gene is inserted near this operon. The presence of mobile DNA could confer instability to this region. In order to examine this, the cat (chloramphenicol acetyltransferase) gene was inserted adjacent to the fljBA operon so that deletions involving this genomic region could be identified. After growing S. enterica chloramphenicol-resistant strains under different conditions, more than 104 colonies were tested for the loss of chloramphenicol resistance. However, none of the colonies were sensitive to chloramphenicol. These data suggest that the origin of S. enterica serovar 4,5,12:i:- from Typhimurium by fljBA deletion is not a frequent event. The origin and dissemination of 4,5,12:i:- raise several questions about the role of flagellar phase variation in virulence.Salmonella enterica subsp enterica serovar 4,5,12:i:- has been responsible for many recent Salmonella outbreaks worldwide. Several studies indicate that this serovar originated from S. enterica subsp enterica serovar Typhimurium, by the loss of the flagel1441905719065FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR2009/15956-7; 2012/10608-3; 2012/05382-6; 2014/11280-7; 2013/11880-1308955/2012-9; 141629/2012-601P-04520-201

    The existence problem for dynamics of dissipative systems in quantum probability

    Full text link
    Motivated by existence problems for dissipative systems arising naturally in lattice models from quantum statistical mechanics, we consider the following C∗C^{\ast}-algebraic setting: A given hermitian dissipative mapping ή\delta is densely defined in a unital C∗C^{\ast}-algebra A\mathfrak{A}. The identity element in A{\frak A} is also in the domain of ή\delta. Completely dissipative maps ή\delta are defined by the requirement that the induced maps, (aij)→(ή(aij))(a_{ij})\to (\delta (a_{ij})), are dissipative on the nn by nn complex matrices over A{\frak A} for all nn. We establish the existence of different types of maximal extensions of completely dissipative maps. If the enveloping von Neumann algebra of A{\frak A} is injective, we show the existence of an extension of ή\delta which is the infinitesimal generator of a quantum dynamical semigroup of completely positive maps in the von Neumann algebra. If ή\delta is a given well-behaved *-derivation, then we show that each of the maps ή\delta and −ή-\delta is completely dissipative.Comment: 24 pages, LaTeX/REVTeX v. 4.0, submitted to J. Math. Phys.; PACS 02., 02.10.Hh, 02.30.Tb, 03.65.-w, 05.30.-

    Klotho and the Aging Process

    Get PDF
    The klotho gene was originally identified as a putative age-suppressing gene in mice that extends life span when overexpressed. It induces complex phenotypes resembling human premature aging syndromes when disrupted. The gene was named after a Greek goddess Klotho who spun the thread of life. Since then, various functional aspects of the klotho gene have been investigated, leading to the identification of multiple novel endocrine axes that regulate various metabolic processes and an unexpected link between mineral metabolism and aging. The purposes of this review were to overview recent progress on Klotho research and to discuss a novel aging mechanism

    Acute Kawasaki Disease: Not Just for Kids

    Get PDF
    Kawasaki Disease is a small-to-medium-vessel vasculitis that preferentially affects children. Kawasaki Disease can occur in adults, but the presentation may differ from that observed in children. Typical findings in both adults and children include fever, conjunctivitis, pharyngitis, and skin erythema progressing to a desquamating rash on the palms and soles. Adults more frequently present with cervical adenopathy (93% of adults vs. 15% of children), hepatitis (65% vs. 10%), and arthralgia (61% vs. 24–38%). In contrast, adults are less frequently affected by meningitis (10% vs. 34%), thrombocytosis (55% vs. 100%), and coronary artery aneurysms (5% vs. 18–25%). We report a case of acute Kawasaki Disease in a 24-year-old man who presented with rash, fever, and arthritis. He was successfully treated with high-dose aspirin and intravenous immunoglobulin (IVIG). Our case highlights the importance of considering Kawasaki Disease in adults presenting with symptoms commonly encountered in a general medical practice

    Progression of coronary artery calcification and cardiac events in patients with chronic renal disease not receiving dialysis

    Get PDF
    We tested for the presence of coronary calcifications in patients with chronic renal disease not on dialysis and studied its progression in 181 consecutive non-dialyzed patients who were followed for a median of 745 days. Coronary calcifications (calcium score) were tallied in Agatston units by computed tomography, and the patients were stratified into two groups by their baseline calcium score (100 U or less and over 100 U). Survival was measured by baseline calcium score and its progression. Cardiac death and myocardial infarction occurred in 29 patients and were significantly more frequent in those patients with calcium scores over 100 U (hazard ratio of 4.11). With a calcium score of 100 U or less, the hazard ratio for cardiac events was 0.41 and 3.26 in patients with absent and accelerated progression, respectively. Thus, in non-dialyzed patients, the extent of coronary calcifications was associated to cardiac events, and progression was an independent predictive factor of cardiac events mainly in less calcified patients. Hence, assessment of coronary calcifications and progression might be useful for earlier management of risk factors and guiding decisions for prevention of cardiac events in this patient population

    Emergence of terpene cyclization in Artemisia annua

    Get PDF
    The emergence of terpene cyclization was critical to the evolutionary expansion of chemical diversity yet remains unexplored. Here we report the first discovery of an epistatic network of residues that controls the onset of terpene cyclization in Artemisia annua. We begin with amorpha-4,11-diene synthase (ADS) and (E)-b-farnesene synthase (BFS), a pair of terpene synthases that produce cyclic or linear terpenes, respectively. A library of B27,000 enzymes is generated by breeding combinations of natural amino-acid substitutions from the cyclic into the linear producer. We discover one dominant mutation is sufficient to activate cyclization, and together with two additional residues comprise a network of strongly epistatic interactions that activate, suppress or reactivate cyclization. Remarkably, this epistatic network of equivalent residues also controls cyclization in a BFS homologue from Citrus junos. Fitness landscape analysis of mutational trajectories provides quantitative insights into a major epoch in specialized metabolism
    • 

    corecore