754 research outputs found

    Manifolds associated with (Z2)n(Z_2)^n-colored regular graphs

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    In this article we describe a canonical way to expand a certain kind of (Z2)n+1(\mathbb Z_2)^{n+1}-colored regular graphs into closed nn-manifolds by adding cells determined by the edge-colorings inductively. We show that every closed combinatorial nn-manifold can be obtained in this way. When n3n\leq 3, we give simple equivalent conditions for a colored graph to admit an expansion. In addition, we show that if a (Z2)n+1(\mathbb Z_2)^{n+1}-colored regular graph admits an nn-skeletal expansion, then it is realizable as the moment graph of an (n+1)(n+1)-dimensional closed (Z2)n+1(\mathbb Z_2)^{n+1}-manifold.Comment: 20 pages with 9 figures, in AMS-LaTex, v4 added a new section on reconstructing a space with a (Z2)n(Z_2)^n-action for which its moment graph is a given colored grap

    A severe case of neuroleukemiosis caused by B cell chronic lymphocytic leukemia, presenting as mononeuritis multiplex.

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    To report an exceptional case of nerve infiltration by an otherwise benign chronic B cell leukemia, inducing severe mononeuritis multiplex. The patient underwent extensive evaluation, including nerve conduction study and myography, brain and plexus MRI, and nerve biopsy. The clinical and electrophysiological diagnosis was a mononeuritis multiplex with severe motor and sensory involvement; only the nerve biopsy allowed definite diagnosis and introduction of chemotherapy, leading to resolution of sensory deficit and progressive motor improvement. Neuroleukemiosis caused by chronic lymphoid leukemia is an exceptional diagnosis. The presence of other possible causes like cryoglobulinemia could induce avoidance of nerve biopsy thus undertreating patient, since steroid treatment is not expected to be efficient on lymphocytic proliferation. Our case stretches the importance of nerve biopsy and raises neuromuscular specialist's awareness of this rare entity

    Setting up an outpatient parenteral antimicrobial therapy (OPAT) unit in Switzerland: review of the first 18 months of activity.

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    Outpatient parenteral antimicrobial therapy (OPAT) has been recognised as a useful, cost-effective and safe alternative to inpatient treatment, but no formal OPAT unit existed in Switzerland until recently. In December 2013 an OPAT unit was established at Lausanne University Hospital. We review here the experience of this new OPAT unit after 18 months of activity. Patient characteristics, clinical activities and outcomes were recorded prospectively. Need and acceptance was evaluated as number of OPAT courses administered and number of patients refusing OPAT. Safety and efficacy were evaluated as: (1) adverse events linked to antimicrobials and catheters, (2) re-admission to hospital, (3) rate of treatment failures and (4) mortality. Over 18 months, 179 courses of OPAT were administered. Acceptance was high with only four patients refusing OPAT. Urinary tract infections with resistant bacteria and musculoskeletal infections were the most common diagnoses. Self-administration of antibiotics using elastomeric pumps became rapidly the most frequently used approach. Sixteen patients presented with adverse events linked to antimicrobials and catheters. OPAT-related readmissions occurred in nine patients. The overall cure rate was 94 %. This study shows that OPAT is very well accepted by patients and medical staff, even in a setting which has not used this type of treatment approach until now. Self-administration using elastomeric pumps proved to be particularly useful, safe and efficient. OPAT offers a good alternative to hospitalisation for patients presenting with infections due to resistant bacteria that cannot be treated orally anymore and for difficult to treat infections

    Borna disease virus infects human neural progenitor cells and impairs neurogenesis.

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    Understanding the complex mechanisms by which infectious agents can disrupt behavior represents a major challenge. The Borna disease virus (BDV), a potential human pathogen, provides a unique model to study such mechanisms. Because BDV induces neurodegeneration in brain areas that are still undergoing maturation at the time of infection, we tested the hypothesis that BDV interferes with neurogenesis. We showed that human neural stem/progenitor cells are highly permissive to BDV, although infection does not alter their survival or undifferentiated phenotype. In contrast, upon the induction of differentiation, BDV is capable of severely impairing neurogenesis by interfering with the survival of newly generated neurons. Such impairment was specific to neurogenesis, since astrogliogenesis was unaltered. In conclusion, we demonstrate a new mechanism by which BDV might impair neural function and brain plasticity in infected individuals. These results may contribute to a better understanding of behavioral disorders associated with BDV infection

    Correlation between computer tomography‐derived scar topography and critical ablation sites in postinfarction ventricular tachycardia

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    BackgroundMyocardial wall thickness (WT) in patients with a prior myocardial infarction has been used to indicate scarring. However, the correlation of WT with sites critical to ventricular tachycardia (VT) has not been previously investigated. The purpose of this study was to correlate electroanatomic mapping data obtained during VT ablation with WT determined by cardiac computed tomography (CT).Methods and resultsCardiac CTs were performed in 15 consecutive patients (mean age 63 ± 10 years, 86% male, left ventricular ejection fraction 27 ± 12%) with a prior infarct referred for VT ablation. The CTs were registered to the electroanatomic maps obtained during the mapping procedure. Pacing was performed throughout the scar at sites with fractionated electrograms and isolated potentials. Ablation sites were identified by pace‐mapping or entrainment‐mapping and these sites were correlated with WT. Bipolar and unipolar voltage amplitude and bipolar electrogram width correlated with WT (correlation coefficient: 0.63, 0.65, and 0.41, respectively, P < 0.001). Ablation target sites were identified for 58 of 113 inducible VTs. The ablation target sites were located on CT‐defined ridges (WT: 4.2 ± 1.2 mm) bordered by areas of thinning (WT: 2.6 ± 1.1 mm, P < 0.0001) in 14 of 15 patients. Ablation targets were found on ridges in 49 of 58 VTs (84%) for which target sites were identified. A total of 70 ridges were localized in the 15 patients. VT became noninducible postablation in 11 of 15 patients (73%).ConclusionWT measured by CT identifies ridges of myocardial tissue that often are critical for postinfarction VT and that can be appropriate target sites for ablation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142923/1/jce13441_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142923/2/jce13441.pd

    Nitrogen Blanketing and Hydrogen Starvation in Dead-Ended-Anode Polymer Electrolyte Fuel Cells Revealed by Hydro-Electro-Thermal Analysis

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    Dead-ended anode operation has a number of practical advantages that simplify system complexity and lower cost for polymer electrolyte fuel cells. However, dead-ended mode leads to performance loss over time which can only be reversed by performing intermittent purge events. This work applies a combined hydro-electro-thermal analysis to an air-cooled open-cathode fuel cell, presenting experimental functional maps of water distribution, current density and temperature. This approach has allowed the identification of a 'nitrogen blanketing' effect due to nitrogen cross-over from the cathode and a 'bypass' effect where a peripheral gap between the gasket and the GDL offers a hydrogen flow 'short circuit' to the border of the electrode. A consequence of high local current density at the margin of the electrode, and resulting high temperatures, may impact the lifetime of the cell in dead-end mode

    Improving Strategies via SMT Solving

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    We consider the problem of computing numerical invariants of programs by abstract interpretation. Our method eschews two traditional sources of imprecision: (i) the use of widening operators for enforcing convergence within a finite number of iterations (ii) the use of merge operations (often, convex hulls) at the merge points of the control flow graph. It instead computes the least inductive invariant expressible in the domain at a restricted set of program points, and analyzes the rest of the code en bloc. We emphasize that we compute this inductive invariant precisely. For that we extend the strategy improvement algorithm of [Gawlitza and Seidl, 2007]. If we applied their method directly, we would have to solve an exponentially sized system of abstract semantic equations, resulting in memory exhaustion. Instead, we keep the system implicit and discover strategy improvements using SAT modulo real linear arithmetic (SMT). For evaluating strategies we use linear programming. Our algorithm has low polynomial space complexity and performs for contrived examples in the worst case exponentially many strategy improvement steps; this is unsurprising, since we show that the associated abstract reachability problem is Pi-p-2-complete
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