7,856 research outputs found

    E-ASTROGAM: A space mission for MeV-GeV gamma-ray astrophysics

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    e-ASTROGAM is an observatory space mission dedicated to the study of the gamma radiation in the range from 0.3 MeV to 3 GeV. The detector is composed by a Silicon tracker, a calorimeter, and an anticoincidence system. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, eASTROGAM will open a new window on the non-thermal Universe. In particular it will determine the origin of key isotopes fundamental for the understanding of supernova explosions and the chemical evolution of our Galaxy. It will also shed light on the processes behind the acceleration of cosmic rays in our Galaxy

    A new numerical method for a class of Volterra and Fredholm integral equations

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    In the present work, we introduce a new numerical method based on a strong version of the mean-value theorem for integrals to solve quadratic Volterra integral equations and Fredholm integral equations of the second kind, for which there are theoretical monotonic non-negative solutions. By means of an equality theorem, the integral that appears in the aforementioned equations is transformed into one that enables a more accurate numerical solution with fewer calculations than other previously described methods. Convergence analysis is given

    PRINCIPLES OF APPLIED BIOMECHANICS ON THE RACE WALKERS: IMPROVEMENT IN PERFORMANCE WITH A PLANTAR ORTHOSIS

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    When race walking it is essential to attain and maintain for a period of time the maximal speed with minimal expenditure of energy, in observance of the prescribed standards. To achieve this end, optimizing the physical carriage is indispensable. This may be done in two ways: I) by reducing those force component hat ace employed along directions of application that do no concur with the sense of progression, since they interfere with and disperse part of the energy; and 2) by increasing the vectorial components that have the same direction as the forward movement. The aim of our work was to verify the modifications that are induced by the use of plantar orthoses , as reflected by parameters of biomechanical performance on the race walker: Under standard reference conditions, we studied the kinematics and ground reaction of 10 highly-trained Athletes. With reference to report that confirmed previous study by us and other authors, we verified the modifications induced by the applications of special dynamic plantar orthoses. The ground reaction appeared to be optimized by the use of these orthoses through the following mechanisms: 1) a diminution of the sagittal force components that are opposed to the direction of movemen6 2) a diminution of the transverse edgewise components that are not useful to the progression, and 3) an increase in the reclamation of useful elastic energy stored by the functional unit, the 'musculo-skeletal footwear system”

    Selecting Technologies for Sour and Ultra-Sour Gas Treating

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    As the cleanest fossil fuel, natural gas plays a key role in the path towards renewables. Considering the increasing gas demand, rich CO2 and H2S gas reserves, in the past considered economically unviable, are becoming fruitful. However, the non-conventional nature of this kind of gases, in addition to the potentially higher production cost, raises the need of new strategies for their monetization, bypassing the conventional approaches. Starting from the huge number of novel large-scale projects for the exploitation of rich-H2S gas fields, this paper overviews the current tendencies in sour and ultra-sour natural gas production, focusing on the removal of sulfur-based compounds, together with H2S and CO2. At first, available technologies for ultra-sour gas treatment are discussed. Then, simulations of the absorption processes based on a real case-study are carried out, in order to verify the effectiveness of the proposed alternatives for the removal of mercaptans, as well as CO2 and H2S. Results are critically analyzed, in view of providing a practical guide of industrial interest for the selection of the most suitable method

    Exact Monte Carlo time dynamics in many-body lattice quantum systems

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    On the base of a Feynman-Kac--type formula involving Poisson stochastic processes, recently a Monte Carlo algorithm has been introduced, which describes exactly the real- or imaginary-time evolution of many-body lattice quantum systems. We extend this algorithm to the exact simulation of time-dependent correlation functions. The techniques generally employed in Monte Carlo simulations to control fluctuations, namely reconfigurations and importance sampling, are adapted to the present algorithm and their validity is rigorously proved. We complete the analysis by several examples for the hard-core boson Hubbard model and for the Heisenberg model

    Nurses' reporting of suspect adverse drug reactions: a mixed-methods study

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    Objective. To assess nurses’ knowledge, attitudes and practices (KAP) towards spontaneous adverse drug reactions (ADRs) reporting. Methods. The mixed-method study was conducted following a quanti-qualitative sequential approach: a survey (using a KAP questionnaire) followed by a focus group was performed. Results. In the quantitative findings, responders (570 hospital nurses) declared that they were unaware of the pharmacovigilance system (58.1%, n = 331); where to find the reporting form (63.5%, n = 362); how fill it in (71.6%, n = 408); to whom and how to send it (65.8%, n = 375). Only 11.1% (n = 63) reported ADRs. The qualitative phase supported the quantitative findings and provided new information about other factors that condition ADR reporting: misinterpretation of the meaning of “reporting”, unawareness of nurses’ autonomy in ADR reporting and fear of consequences after ADR reporting. Conclusion. Nurses are not fully aware of their role in ADR reporting. We recommend educational interventions and management changes

    Saturation of Turbulent Drag Reduction in Dilute Polymer Solutions

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    Drag reduction by polymers in turbulent wall-bounded flows exhibits universal and non-universal aspects. The universal maximal mean velocity profile was explained in a recent theory. The saturation of this profile and the crossover back to the Newtonian plug are non-universal, depending on Reynolds number Re, concentration of polymer cpc_p and the degree of polymerization NpN_p. We explain the mechanism of saturation stemming from the finiteness of extensibility of the polymers, predict its dependence on cpc_p and NN in the limit of small cpc_p and large Re, and present the excellent comparison of our predictions to experiments on drag reduction by DNA.Comment: 4 pages, 4 figs., included, PRL, submitte

    Aesthetic satisfaction in lip and palate clefts: a comparative study between secondary and tertiary bone grafting

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    Lip and palate cleft represent one of the most frequently occurring congenital deformity, which includes dental anomalies, such as variation in tooth number and position. In case of hypodontia implant-prosthetic rehabilitation offers significant advantages in terms of function, aesthetics and quality of life and bone graft is usually needed. Secondary bone grafting, generally performed in the mixed dentition phase (years 8-11) seems to be the most successful method to allow for rehabilitation. It's often necessary to perform a tertiary bone grafting in adult age in order to achieve better bone quantity and quality before implant placement. Aim of this retrospective study was to evaluate the aesthetic perception that patients had of themselves comparing dental implants placed in tertiary grafted alveolar cleft sites with a previous secondary grafting to only secondary grafting. Between 2009 and 2012, fourteen alveolar cleft were treated with implant rehabilitation and eleven of them received tertiary bone grafting six months prior to implant placement. All patients were questioned to give a score from 1 to 10 their aesthetic satisfaction of their smile before and after implant rehabilitation and during pre-surgery provisional rehabilitation. At the end of their prosthesis rehabilitation patients who received tertiary bone grafting resulted more satisfied than those who had secondary bone grafting only (9.5 vs 8)
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