3,144 research outputs found

    Von Neumann Regular Cellular Automata

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    For any group GG and any set AA, a cellular automaton (CA) is a transformation of the configuration space AGA^G defined via a finite memory set and a local function. Let CA(G;A)\text{CA}(G;A) be the monoid of all CA over AGA^G. In this paper, we investigate a generalisation of the inverse of a CA from the semigroup-theoretic perspective. An element τ∈CA(G;A)\tau \in \text{CA}(G;A) is von Neumann regular (or simply regular) if there exists σ∈CA(G;A)\sigma \in \text{CA}(G;A) such that τ∘σ∘τ=τ\tau \circ \sigma \circ \tau = \tau and σ∘τ∘σ=σ\sigma \circ \tau \circ \sigma = \sigma, where ∘\circ is the composition of functions. Such an element σ\sigma is called a generalised inverse of τ\tau. The monoid CA(G;A)\text{CA}(G;A) itself is regular if all its elements are regular. We establish that CA(G;A)\text{CA}(G;A) is regular if and only if ∣G∣=1\vert G \vert = 1 or ∣A∣=1\vert A \vert = 1, and we characterise all regular elements in CA(G;A)\text{CA}(G;A) when GG and AA are both finite. Furthermore, we study regular linear CA when A=VA= V is a vector space over a field F\mathbb{F}; in particular, we show that every regular linear CA is invertible when GG is torsion-free elementary amenable (e.g. when G=Zd, d∈NG=\mathbb{Z}^d, \ d \in \mathbb{N}) and V=FV=\mathbb{F}, and that every linear CA is regular when VV is finite-dimensional and GG is locally finite with Char(F)∀o(g)\text{Char}(\mathbb{F}) \nmid o(g) for all g∈Gg \in G.Comment: 10 pages. Theorem 5 corrected from previous versions, in A. Dennunzio, E. Formenti, L. Manzoni, A.E. Porreca (Eds.): Cellular Automata and Discrete Complex Systems, AUTOMATA 2017, LNCS 10248, pp. 44-55, Springer, 201

    Cancer Mortality in Older Mexican Individuals (2000 – 2010)

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    The article shows the trends of cancer mortality in older mexican individuals during the period from 2000 to 201

    Two Boundaries Separate Borrelia burgdorferi Populations in North America

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    Understanding the spread of infectious diseases is crucial for implementing effective control measures. For this, it is important to obtain information on the contemporary population structure of a disease agent and to infer the evolutionary processes that may have shaped it. Here, we investigate on a continental scale the population structure of Borrelia burgdorferi, the causative agent of Lyme borreliosis (LB), a tick-borne disease, in North America. We test the hypothesis that the observed d population structure is congruent with recent population expansions and that these were preceded by bottlenecks mostly likely caused by the near extirpation in the 1900s of hosts required for sustaining tick populations. Multilocus sequence typing and complementary population analytical tools were used to evaluate B. burgdorferi samples collected in the Northeastern, Upper Midwestern, and Far-Western United States and Canada. The spatial distribution of sequence types (STs) and inferred population boundaries suggest that the current populations are geographically separated. One major population boundary separated western B. burgdorferi populations transmitted by Ixodes pacificus in California from Eastern populations transmitted by I. scapularis; the other divided Midwestern and Northeastern populations. However, populations from all three regions were genetically closely related. Together, our findings suggest that although the contemporary populations of North American B. burgdorferi now com- prise three geographically separated subpopulations with no or limited gene flow among them, they arose from a common ancestral population. A comparative analysis of the B. burgdorferi outer surface protein C (ospC) gene revealed novel linkages and provides additional insights into the genetic characteristics of strains

    Finding Respondents from Minority Groups

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    The recruitment of respondents belonging to ethnic minorities poses important challenges in social and health research. This paper reflects on the enablers and barriers to recruitment that we encountered in our research work with persons belonging to ethnic minorities. Additionally, we applied the Matching Model of Recruitment, a theoretical framework concerning minority recruitment, to guide our reflection. We also explored its applicability as a research design tool. In assessing our research experience, we learned that minority recruitment in social and health research is influenced by the social context of all key players involved in the research. Also, there are enablers and barriers within that social context facilitating or delaying the recruitment process. The main enablers to recruit respondents belonging to ethnic minorities include working with community agencies and gatekeepers who share a common vision with researchers and the latter’s ability to gain the trust of potential respondents. The main barriers include demanding too much from these same community agencies and gatekeepers and ignoring factors that could delay the completion of the research. Although we found the Matching Model of Recruitment to be an effective tool in assessing the processes of recruiting respondents belonging to ethnic minorities, further empirical research is needed to explore its usefulness during the research planning phase

    T-cell derived acetylcholine aids host defenses during enteric bacterial infection with Citrobacter rodentium.

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    The regulation of mucosal immune function is critical to host protection from enteric pathogens but is incompletely understood. The nervous system and the neurotransmitter acetylcholine play an integral part in host defense against enteric bacterial pathogens. Here we report that acetylcholine producing-T-cells, as a non-neuronal source of ACh, were recruited to the colon during infection with the mouse pathogen Citrobacter rodentium. These ChAT+ T-cells did not exclusively belong to one Th subset and were able to produce IFNÎł, IL-17A and IL-22. To interrogate the possible protective effect of acetylcholine released from these cells during enteric infection, T-cells were rendered deficient in their ability to produce acetylcholine through a conditional gene knockout approach. Significantly increased C. rodentium burden was observed in the colon from conditional KO (cKO) compared to WT mice at 10 days post-infection. This increased bacterial burden in cKO mice was associated with increased expression of the cytokines IL-1ÎČ, IL-6, and TNFα, but without significant changes in T-cell and ILC associated IL-17A, IL-22, and IFNÎł, or epithelial expression of antimicrobial peptides, compared to WT mice. Despite the increased expression of pro-inflammatory cytokines during C. rodentium infection, inducible nitric oxide synthase (Nos2) expression was significantly reduced in intestinal epithelial cells of ChAT T-cell cKO mice 10 days post-infection. Additionally, a cholinergic agonist enhanced IFNÎł-induced Nos2 expression in intestinal epithelial cell in vitro. These findings demonstrated that acetylcholine, produced by specialized T-cells that are recruited during C. rodentium infection, are a key mediator in host-microbe interactions and mucosal defenses

    Streptococcus lutetiensis Bacteremia. First Clindamycin Resistant Isolate Carrying lnuB Gene

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    First Case of Streptococcus lutetiensis Bacteremia Involving a Clindamycin-Resistant Isolate Carrying the lnuB Gene.Fil: Almuzara, Marisa. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de BioquĂ­mica ClĂ­nica; ArgentinaFil: Bonofiglio, Laura. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de MicrobiologĂ­a, InmunologĂ­a y BiotecnologĂ­a; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay; ArgentinaFil: Cittadini, Roberto Arnaldo. Instituto Nacional de Tecnologia Agropecuaria; Argentina. Sanatorio Mater Dei; ArgentinaFil: Vera Ocampo, Cecilia. Sanatorio Mater Dei; ArgentinaFil: Montilla, A.. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas . Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Inmunologia, Genetica y Metabolismo; ArgentinaFil: del Castillo, M.. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de MicrobiologĂ­a, InmunologĂ­a y BiotecnologĂ­a; ArgentinaFil: Ramirez, Maria Soledad. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones en MicrobiologĂ­a y ParasitologĂ­a MĂ©dica; ArgentinaFil: Mollerach, Marta Eugenia. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de MicrobiologĂ­a, InmunologĂ­a y BiotecnologĂ­a; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Vay, Carlos Alberto. Universidad de Buenos Aires. Facultad de Farmacia y BioquĂ­mica. Departamento de BioquĂ­mica ClĂ­nica; Argentin

    Cosmic acceleration from asymmetric branes

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    We consider a single 3-brane sitting in between two different five dimensional spacetimes. On each side of the brane, the bulk is a solution to Gauss-Bonnet gravity, although the bare cosmological constant, funda mental Planck scale, and Gauss-Bonnet coupling can differ. This asymmetry leads to weighted junction conditions across the brane and interesting brane cosmology. We focus on two special cases: a generalized Randall-Sundrum model without any Gauss-Bonnet terms, and a stringy model, without any bare cosmological constants, and positive Gauss-Bonnet coupling. Even though we assume there is no vacuum energy on the brane, we find late time de Sitter cosmologies can occur. Remarkably, in certain parameter regions, this acceleration is preceded by a period of matter/radiation domination, with H2∝ρH^2 \propto \rho, all the way back to nucleosynthesis.Comment: Version appearing in CQ
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