657 research outputs found

    Coulomb-Volkov approach of ionization by extreme ultraviolet laser pulses in the subfemtosecond regime

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    In conditions where the interaction betweeen an atom and a short high-frequency extreme ultraviolet laser pulse is a perturbation, we show that a simple theoretical approach, based on Coulomb-Volkov-type states, can make reliable predictions for ionization. To avoid any additional approximation, we consider here a standard case : the ionization of hydrogen atoms initially in their ground state. For any field parameter, we show that the method provides accurate energy spectra of ejected electrons, including many above threshold ionization peaks, as long as the two following conditions are simultaneously fulfilled : (i) the photon energy is greater than or equal to the ionization potential ; (ii) the ionization process is not saturated. Thus, ionization of atoms or molecules by the high order harmonic laser pulses which are generated at present may be addressed through this Coulomb-Volkov treatment.Comment: 19 pages including 5 figures and figure caption

    Synchronized flow and wide moving jams from balanced vehicular traffic

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    Recently we proposed an extension to the traffic model of Aw, Rascle and Greenberg. The extended traffic model can be written as a hyperbolic system of balance laws and numerically reproduces the reverse λ\lambda shape of the fundamental diagram of traffic flow. In the current work we analyze the steady state solutions of the new model and their stability properties. In addition to the equilibrium flow curve the trivial steady state solutions form two additional branches in the flow-density diagram. We show that the characteristic structure excludes parts of these branches resulting in the reverse λ\lambda shape of the flow-density relation. The upper branch is metastable against the formation of synchronized flow for intermediate densities and unstable for high densities, whereas the lower branch is unstable for intermediate densities and metastable for high densities. Moreover, the model can reproduce the typical speed of the downstream front of wide moving jams. It further reproduces a constant outflow from wide moving jams, which is far below the maximum free flow. Applying the model to simulate traffic flow at a bottleneck we observe a general pattern with wide moving jams traveling through the bottleneck.Comment: 10 pages, 12 figure

    Efficacy of an autogenous vaccine against highly virulent "Staphylococcus aureus" infection in rabbits

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    [EN] The efficacy of an autogenous vaccine consisting of a whole cell suspension of formalin killed bacteria in sterile buffered saline against Staphylococcus aureus infections was determined, using a well-established rabbit skin infection model. Thirteen eight-week-old rabbits were vaccinated twice subcutaneously with a two-week interval while ten rabbits were injected twice with sterile buffered saline. Two weeks after the last injection, ten vaccinated and all PBS-injected rabbits were inoculated intradermally with 108 cfu of a S. aureus strain which had been shown to be highly virulent for rabbits. Three vaccinated animals served as negative controls and were intradermally injected with sterile buffered saline. All rabbits were examined daily for the development of skin lesions until fourteen days after the experimental infection when all rabbits were euthanised. All animals experimentally infected with S. aureus developed skin abscesses within 24 hours post-inoculation, but in the vaccinated group the maximum abscess diameter was significantly lower than in the non-vaccinated group (P=0.048). The difference between the autovaccinated and non-vaccinated group increased over time (P<0.001). These results indicate that vaccination with an inactivated whole cell bacterin may be useful for control of staphylococcosis in rabbits but does not prevent abscess formation in animals inoculated with a high dose of a highly virulent S. aureus strain.Meulemans, G.; Haesebrouck, F.; Lipinska, U.; Duchateau, L.; Hermans, K. (2011). Efficacy of an autogenous vaccine against highly virulent "Staphylococcus aureus" infection in rabbits. World Rabbit Science. 19(1):1-9. https://doi.org/10.4995/wrs.2011.8121919

    Proteolysis in milk during experimental Escherichia coli mastitis

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    This work consisted of the intramammary infections (IMI) of 8 heifers by high doses of Escherichia coli to study both the proteolytic activity in milk and the resulting peptides. Therefore, a milking kinetic has been followed, and several parameters have been studied, such as proteose peptones ( PP) fraction ( quantitative and qualitative changes), plasmin activity (PA), milk somatic cell count (SCC), and bacterial count. A qualitative study of milk proteins and PP was performed by sodium dodecyl sulfate-PAGE, and the peptides recovered in PP during the acute phase of inflammation were amino-terminal micro-sequenced. A BSA increase in milk over time supported the hypothesis of an increase in the permeability of the epithelial barrier. A significant increase in PP content, considered to be an indicator of proteolysis, was observed from postinfusion hours (PIH) 12 to 48. Both the E. coli bacterial count and the SCC increased from PIH 3 to 216. Plasmin activity was increased noticeably from PIH 15 to 24. The respective increases in SCC, bacterial count, and PA suggest their involvement in a global mechanism responsible for the increase in proteolysis in milk after E. coli challenge. Somatic cell count and E. coli may be involved from PIH 3 to 216, and PA involvement might be highlighted during the maximum proteolysis, from PIH 15 to 24. A qualitative study of PP fraction by electrophoresis revealed the apparition of 5 peptide bands: P1 and P2 previously recovered during the lipopolysaccharide challenge, and E1 (27.0 kDa), E2 (15.5 kDa), and E3 (9.0 kDa) were specific to E. coli challenge; E1, E2, and E3 contained casein fragments. The roles played by leukocytes and E. coli are discussed

    Does cardiac surgery in newborn infants compromise blood cell reactivity to endotoxin?

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    INTRODUCTION: Neonatal cardiac surgery is associated with a systemic inflammatory reaction that might compromise the reactivity of blood cells against an inflammatory stimulus. Our prospective study was aimed at testing this hypothesis. METHODS: We investigated 17 newborn infants with transposition of the great arteries undergoing arterial switch operation. Ex vivo production of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), of the regulator of the acute-phase response IL-6, and of the natural anti-inflammatory cytokine IL-10 were measured by enzyme-linked immunosorbent assay in the cell culture supernatant after whole blood stimulation by the endotoxin lipopolysaccharide before, 5 and 10 days after the operation. Results were analyzed with respect to postoperative morbidity. RESULTS: The ex vivo production of TNF-α and IL-6 was significantly decreased (P < 0.001 and P < 0.002, respectively), whereas ex vivo production of IL-10 tended to be lower 5 days after the operation in comparison with preoperative values (P < 0.1). Ex vivo production of all cytokines reached preoperative values 10 days after cardiac surgery. Preoperative ex vivo production of IL-6 was inversely correlated with the postoperative oxygenation index 4 hours and 24 hours after the operation (P < 0.02). In contrast, postoperative ex vivo production of cytokines did not correlate with postoperative morbidity. CONCLUSION: Our results show that cardiac surgery in newborn infants is associated with a transient but significant decrease in the ex vivo production of the pro-inflammatory cytokines TNF-α and IL-6 together with a less pronounced decrease in IL-10 production. This might indicate a transient postoperative anti-inflammatory shift of the cytokine balance in this age group. Our results suggest that higher preoperative ex vivo production of IL-6 is associated with a higher risk for postoperative pulmonary dysfunction

    SPM to the heart: mapping of 4D continuous velocities for motion abnormality quantification

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    International audienceThis paper proposes to apply parallel transport and statistical atlas techniques to quantify 4D myocardial motion abnormalities. We take advantage of our previous work on cardiac motion , which provided a continuous spatiotemporal representation of velocities, to interpolate and reorient cardiac motion fields to an unbiased reference space. Abnormal motion is quantified using SPM analysis on the velocity fields, which includes a correction based on random field theory to compensate for the spatial smoothness of the velocity fields. This paper first introduces the imaging pipeline for constructing a continuous 4D velocity atlas. This atlas is then applied to quantify abnormal motion patterns in heart failure patients

    Experimental infection model for vibriosis in Dover sole (<i>Solea solea</i>) larvae as an aid in studying its pathogenesis and alternative treatments

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    Severe economic losses due to diseases in marine larviculture may be linked to vibriosis. To better understand the pathogenesis of vibriosis and evaluate new ways to prevent and combat this important disease, there is a great need for reliable and reproducible experimental infection models. The present study aimed at developing a challenge model for vibriosis in Dover sole larvae and testing its applicability to study the effect of the probiotic treatment. For that purpose, larvae were challenged at 10 days post hatching with Vibrio anguillarum WT, V. anguillarum HI610 or V. harveyi WT. Following administration of V. anguillarum WT via immersion at 1 × 107 colony forming units/mL, a larval mortality of 50% was observed at 17 days post-inoculation. In a next step, the probiotic potential of 371 isolates retrieved from Dover sole was assessed by screening for their inhibitory effects against Vibrio spp. and absence of haemolytic activity. One remaining isolate (V. proteolyticus) and V. lentus, known for its protective characteristics in seabass larvae, were further tested in vivo by means of the pinpointed experimental infection model. Neither isolate provided via the water or feed proved to be protective for the Dover sole larvae against challenge with V. anguillarum WT. This developed challenge model constitutes a firm basis to expedite basic and applied research regarding the pathogenesis and treatment of vibriosis as well as for studying the impact of (a)biotic components on larval health

    Removal of a below knee plaster cast worn for 28 months: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>An unusual situation in which a below knee cast was removed after 28 months is reported. To the best of our knowledge no similar cases have been reported in the literature.</p> <p>Case presentation</p> <p>The cast was removed from the leg of a 45-year-old Caucasian woman. Significant muscle atrophy and dense skin scales were present but the underlying skin surface was relatively healthy with only small pitted 1-2 mm ulcers. No pathogenic organisms were cultured from this environment.</p> <p>Conclusion</p> <p>It seems likely that skin can tolerate cast immobilization for prolonged duration.</p

    Gene expression of INPP5F as an independent prognostic marker in fludarabine-based therapy of chronic lymphocytic leukemia

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    Chronic lymphocytic leukemia (CLL) is a heterogeneous disease. Various disease-related and patient-related factors have been shown to influence the course of the disease. The aim of this study was to identify novel biomarkers of significant clinical relevance. Pretreatment CD19-separated lymphocytes (n = 237;discovery set) and peripheral blood mononuclear cells (n = 92;validation set) from the REACH trial, a randomized phase III trial in relapsed CLL comparing rituximab plus fludarabine plus cyclophosphamide with fludarabine plus cyclophosphamide alone, underwent gene expression profiling. By using Cox regression survival analysis on the discovery set, we identified inositol polyphosphate-5-phosphatase F (INPP5F) as a prognostic factor for progression-free survival (P<0.001;hazard ratio (HR),1.63;95% confidence interval (CI),1.35-1.98) and overall survival (Po0.001;HR, 1.47;95% CI, 1.18-1.84),regardless of adjusting for known prognostic factors. These findings were confirmed on the validation set, suggesting that INPP5F may serve as a novel, easy-to-assess future prognostic biomarker for fludarabine-based therapy in CLL
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