419 research outputs found

    Anisotropic constitutive equations and experimental tensile behavior of brain tissue

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    The present study deals with the experimental analysis and mechanical modeling of tensile behavior of brain soft tissue. A transversely isotropic hyperelastic model recently proposed by Meaney (2003) is adopted and mathematically studied under uniaxial loading conditions. Material parameter estimates are obtained through tensile tests on porcine brain materials accounting for regional and directional differences. Attention is focused on the short-term response. An extrapolation of tensile test data to the compression range is performed theoretically, to study the effect of the heterogeneity in the tensile/compressive response on the material parameters. Experimental and numerical results highlight the sensitivity of the adopted model to the test direction

    Can Twitter be a source of information on allergy? Correlation of pollen counts with tweets reporting symptoms of allergic rhinoconjunctivitis and names of antihistamine drugs

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    Pollen forecasts are in use everywhere to inform therapeutic decisions for patients with allergic rhinoconjunctivitis (ARC). We exploited data derived from Twitter in order to identify tweets reporting a combination of symptoms consistent with a case definition of ARC and those reporting the name of an antihistamine drug. In order to increase the sensitivity of the system, we applied an algorithm aimed at automatically identifying jargon expressions related to medical terms. We compared weekly Twitter trends with National Allergy Bureau weekly pollen counts derived from US stations, and found a high correlation of the sum of the total pollen counts from each stations with tweets reporting ARC symptoms (Pearson's correlation coefficient: 0.95) and with tweets reporting antihistamine drug names (Pearson's correlation coefficient: 0.93). Longitude and latitude of the pollen stations affected the strength of the correlation. Twitter and other social networks may play a role in allergic disease surveillance and in signaling drug consumptions trends

    Radiation and magnetic field effects on new semiconductor power devices for HL-LHC experiments

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    The radiation hardness of commercial Silicon Carbide and Gallium Nitride power MOSFETs is presented in this paper, for Total Ionizing Dose effects and Single Event Effects, under gamma, neutrons, protons and heavy ions. Similar tests are discussed for commercial DC-DC converters, also tested in operation under magnetic field

    Determination of recombination length of a non-equilibrium plasma produced by laser ablation

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    An experimental study of the laser ablation produced plasma evolution is necessary for its deeper understanding, since plasma expansion has both spatially and temporally varying characteristics. We irradiated a Cu target with a KrF laser beam. A small Faraday cup array and an axial Faraday cup were used as diagnostic systems, in order to study the spatial variation in the total charge carried by plasma ions. Charge loss during the plasma expansion was observed, which was attributed to the charged species recombination. This occurred upstream to the critical distance where the plasma density is high enough. Downstream the critical distance the plasma particles collisions were negligible and the ion charge remained frozen. In these experiments it was observed that the critical distance for charge recombination was a function of laser fluence

    Ion beams delivered by two accelerating gaps for industrial and therapeutic applications

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    Laser ion sources offer the possibility to get ion beams utilizable to improve particle accelerators. Today many laboratories, as well as the LEAS, are involved to develop accelerators of very contained dimensions, easy to be installed in little laboratories and hospitals. Pulsed lasers at intensities of the order of 108 W/cm2 and of ns pulse duration, interacting with solid matter in vacuum, produce plasma of high temperature and density. The charge state distribution of the plasma generates high electric fields which accelerate ions along the normal to the target surface. The energy of emitted ions has a shifted Maxwell-Boltzmann distribution which depends on the ion charge state. To increase the ion energy, a post-acceleration system can be employed by means of high voltage power supplies of about 100 kV. The post acceleration system results a good method to obtain high ion currents using a not expensive system and the final ion beams find interesting applications in the field of the ion implantations, hadrontherapy, scientific applications and industrial use. In this work we study the electromagnetic and geometric proper-ties, like the emittance of the beams delivered by Cu target. Plasma‟s characterization was performed us-ing a Faraday cup for the electromagnetic characteris-tics, while for the geometric ones by adopting a pep-per pot system. Applying 60 kV of accelerating volt-age and a laser irradiance of 0.1 GW/cm2, we obtain 5.5 mA of output current and a normalized beam emittance of 0.2 π mm mrad. The brightness of the beams was 137 mA(p mm mrad)-2

    Study of MicroPattern Gaseous detectors with novel nanodiamond based photocathodes for single photon detection in EIC RICH

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    Identification of high momentum hadrons at the future EIC is crucial, gaseous RICH detectors are therefore viable option. Compact collider setups impose to construct RICHes with small radiator length, hence significantly limiting the number of detected photons. More photons can be detected in the far UV region, using a windowless RICH approach. QE of CsI degrades under strong irradiation and air contamination. Nanodiamond based photocathodes (PCs) are being developed as an alternative to CsI. Recent development of layers of hydrogenated nanodiamond powders as an alternative photosensitive material and their performance, when coupled to the THick Gaseous Electron Multipliers (THGEM)-based detectors, are the objects of an ongoing R\&D. We report about the initial phase of our studies.Comment: 3 pages, 5 figures, RICH2018 conference proceedin

    Study of Faraday cups for fast ion beams provided by a LIS source

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    Faraday cups are widely utilized to characterize ion and electrons beams. Owing to the secondary electron emission (SEE) induced by the collision of beams with collectors, wrong measurements could emerge from these detectors. To overcome this problem a polarized grid is utilized in front the cup collector at a negative voltage with respect to the collector. Unfortunately, the high voltage connection of the Faraday cups is hard to obtain. Then, in this work we want to study the secondary emission on different Al ion collector designs having tilted surfaces with respect to beam axis. Tests were performed using ion beams accelerated by a power supply up to 40 kV. The results by the modified collector surfaces were compared to the ones performed with a simple flat collector. The results we obtained point out that the secondary electron emission enhanced on incident beam energy and on the angle with respect to the normal direction of the surface. The ratio of the SEE to angle value results constant for the accelerating voltage and the possibility to design an ion collector able to reset the SEE seems not to be reached

    Postgrafting administration of granulocyte colony-stimulating factor impairs functional immune recovery in recipients of human leukocyte antigen haplotype–mismatched hematopoietic transplants

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    AbstractIn human leukocyte antigen haplotype–mismatched transplantation, extensive T-cell depletion prevents graft-versus-host disease (GVHD) but delays immune recovery. Granulocyte colony-stimulating factor (G-CSF) is given to donors to mobilize stem cells and to recipients to ensure engraftment. Studies have shown that G-CSF promotes T-helper (Th)-2 immune deviation which, unlike Th1 responses, does not protect against intracellular pathogens and fungi. The effect of administration of G-CSF to recipients of mismatched hematopoietic transplants with respect to transplantation outcome and functional immune recovery was investigated. In 43 patients with acute leukemia who received G-CSF after transplantation, the engraftment rate was 95%. However, the patients had a long-lasting type 2 immune reactivity, ie, Th2-inducing dendritic cells not producing interleukin 12 (IL-12) and high frequencies of IL-4– and IL-10–producing CD4+ cells not expressing the IL-12 receptor ÎČ2 chain. Similar immune reactivity patterns were observed on exposure of donor cells to G-CSF. Elimination of postgrafting administration of G-CSF in a subsequent series of 36 patients with acute leukemia, while not adversely affecting engraftment rate (93%), resulted in the anticipated appearance of IL-12–producing dendritic cells (1-3 months after transplantation versus > 12 months in transplant recipients given G-CSF), of CD4+ cells of a mixed Th0/Th1 phenotype, and of antifungal T-cell reactivity in vitro. Moreover, CD4+ cell counts increased in significantly less time. Finally, elimination of G-CSF–mediated immune suppression did not significantly increase the incidence of GVHD (< 15%). Thus, this study found that administration of G-CSF to recipients of T-cell–depleted hematopoietic transplants was associated with abnormal antigen-presenting cell functions and T-cell reactivity. Elimination of postgrafting administration of G-CSF prevented immune dysregulation and accelerated functional immune recovery

    Lifestyle Modifications to Help Prevent Headache at a Developmental Age

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    Headache is the world's seventh most significant cause of disability-adjusted-life in people aged between 10 and 14 years. Therapeutic management is based on pharmacological approaches and lifestyle recommendations. Many studies show associations between each migraine-promoting lifestyle, behavioral triggers, frequency, and intensity of headaches. Nevertheless, the overall aspects of this topic lack any definitive evidence. Educational programs advise that pediatric patients who suffer from migraines follow a correct lifestyle and that this is of the utmost importance in childhood, as it will improve quality of life and assist adult patients in avoiding headache chronicity, increasing general well-being. These data are important due to the scarcity of scientific evidence on drug therapy for prophylaxis during the developmental age. The "lifestyle recommendations" described in the literature include a perfect balance between regular sleep and meal, adequate hydration, limited consumption of caffeine, tobacco, and alcohol, regular physical activity to avoid being overweight as well as any other elements causing stress. The ketogenic diet is a possible new therapeutic strategy for the control of headache in adults, however, the possible role of dietary factors requires more specific studies among children and adolescents. Educational programs advise that the improvement of lifestyle as a central element in the management of pediatric headache will be of particular importance in the future to improve the quality of life of these patients and reduce the severity of cephalalgic episodes and increase their well-being in adulthood. The present review highlights how changes in different aspects of daily life may determine significant improvements in the management of headaches in people of developmental age
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