1,008 research outputs found

    When is a parasite not a parasite? Effects of larval tick burdens on white-footed mouse survival

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    Many animal species can carry considerable burdens of ectoparasites: parasites living on the outside of a host's body. Ectoparasite infestation can decrease host survival, but the magnitude and even direction of survival effects can vary depending on the type of ectoparasite and the nature and duration of the association. When ectoparasites also serve as vectors of pathogens, the effects of ectoparasite infestation on host survival have the potential to alter disease dynamics by regulating host populations and stabilizing transmission. We quantified the impact of larval Ixodes scapularis tick burdens on both within-season and overwinter survival of white-footed mice (Peromyscus leucopus) using a hierarchical Bayesian capture-mark-recapture model. I. scapularis and P. leucopus are, respectively, vectors and competent reservoirs for the causative agents of Lyme disease, anaplasmosis, and babesiosis. Using a data set of 5587 individual mouse capture histories over sixteen years, we found little evidence for any effect of tick burdens on either within-season or overwinter mouse survival probabilities. In male mice, tick burdens were positively correlated with within-season survival probabilities. Mean maximum tick burdens were also positively correlated with population rates of change during the concurrent breeding season. The apparent indifference of mice to high tick burdens may contribute to their effectiveness as reservoir hosts for several human zoonotic pathogens.Fil: Hersh, Michelle H.. Cary Institute of Ecosystem Studies; Estados Unidos. Bard College. Program in Biology; Estados Unidos. Sarah Lawrence College; Estados UnidosFil: LaDeau, Shannon L.. Cary Institute of Ecosystem Studies; Estados UnidosFil: Previtali, Maria Andrea. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Santa Fe; ArgentinaFil: Ostfeld, Richard S.. Cary Institute of Ecosystem Studies; Estados Unido

    Scintillating double beta decay bolometers

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    We present the results obtained in the development of scintillating Double Beta Decay bolometers. Several Mo and Cd based crystals were tested with the bolometric technique. The scintillation light was measured through a second independent bolometer. A 140 g CdWO_4 crystal was run in a 417 h live time measurement. Thanks to the scintillation light, the alpha background is easily discriminated resulting in zero counts above the 2615 keV gamma line of Thallium 208. These results, combined with an extremely easy light detector operation, represent the first tangible proof demonstrating the feasibility of this kind of technique.Comment: 15 pages, 8 figure

    Analysis of a possible application of a new process for oxygen enriched air production

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    A new process for oxygen enriched air (EA) production has been applied to Claus Process. This process is simple and requires few process units. Matlab and Aspen Hysys have been used for simulations and system sizing. The results demonstrate that it could be an alternative to traditional EA processes from an economical point of view

    Critical Current Studies on Deformed Nb-Ti Strands

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    The Nb-Ti hard conductors used in LHC dipole and quadrupole magnets are Rutherford cables composed of several tens of strands. During the cabling process, the strands are severely compacted especially at the thin edge of the cable. In order to assess, on the whole wire length, the deformation effect on the transport current of the wires, LHC-type Nb-Ti superconducting strands of various types were flattened by means of rollers. The critical current was then measured as a function of deformation and applied magnetic field at both 4.3 K and 1.9 K. The measurements were performed for both orientations (flat face perpendicular or parallel to magnetic field). The critical current density anisotropy of such deformed strands and the correlation with magnetization effects are discussed. This study permits to better understand and to quantify the critical current degradation of few percent observed in strands due to cabling. Comparisons with wires extracted from Rutherford cables are presented

    Enhancing productivity and efficiency in conventional laser metal deposition process for Inconel 718 – Part II: advancing the process performance

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    This paper is the second part of a work focused on optimizing the performance of conventional Laser Metal Deposition (C-LMD) process for Inconel 718 (IN718). In Part I, through an extensive experimental campaign on single tracks, the interplay between process parameters and their impact on the deposition rate, powder catchment efficiency, and clad geometry is examined. The parameters investigated include laser power, scan speed, powder feed rate, and standoff distance. By systematically adjusting these parameters, the aim is to identify optimal conditions that maximize productivity while maintaining a favorable clad shape for multi-pass multi-layer depositions. Part II starts from the findings and results of Part I by continuing the optimization on thick wall structures. These are utilized to assess the effect of 3D geometrical process parameters, specifically hatch spacing and Z-step, on process performance and stability. Based on the findings, further optimization procedure is presented, pushing the boundaries of the C-LMD process for IN718. By fine-tuning the process parameters, the capability of the C-LMD process to deposit fully dense IN718 with a productivity of 1500 g/h and a powder catchment efficiency of 70% is demonstrated. These results highlight the potential of C-LMD as a viable manufacturing technique for efficiently fabricating large components. Overall, this study contributes to a deeper understanding of the relationship between process parameters and performance in C-LMD for IN718. The insights gained from this research can guide the development of efficient and cost-effective LMD strategies, facilitating the practical implementation of this process in various industries

    Measurements of the effect of collisions on transverse beam halo diffusion in the Tevatron and in the LHC

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    Beam-beam forces and collision optics can strongly affect beam lifetime, dynamic aperture, and halo formation in particle colliders. Extensive analytical and numerical simulations are carried out in the design and operational stage of a machine to quantify these effects, but experimental data is scarce. The technique of small-step collimator scans was applied to the Fermilab Tevatron collider and to the CERN Large Hadron Collider to study the effect of collisions on transverse beam halo dynamics. We describe the technique and present a summary of the first results on the dependence of the halo diffusion coefficient on betatron amplitude in the Tevatron and in the LHC.Comment: 4 pages, 2 figures. Submitted to the Proceedings of the ICFA Mini-Workshop on Beam-beam Effects in Hadron Colliders (BB2013), Geneva, Switzerland, 18-22 March 201

    New experimental limits on the alpha decays of lead isotopes

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    For the first time a PbWO4 crystal was grown using ancient Roman lead and it was run as a cryogenic detector. Thanks to the simultaneous and independent read-out of heat and scintillation light, the detector was able to discriminate beta/gamma interactions with respect to alpha particles down to low energies. New more stringent limits on the alpha decays of the lead isotopes are presented. In particular a limit of T_{1/2} > 1.4*10^20 y at a 90% C.L. was evaluated for the alpha decay of 204Pb to 200Hg
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