1,538 research outputs found
A taxonomy of multi-industry labour force skills
No full textThis paper proposes an empirical study of the skill repertoires of 290 sectors in the United States over the period 2002–2011. We use information on employment structures and job content of occupations to flesh out structural characteristics of industry-specific know-how. The exercise of mapping the skills structures embedded in the workforce yields a taxonomy that discloses novel nuances on the organization of industry. In so doing we also take an initial step towards the integration of labour and employment in the area of innovation studies
Changing boundaries and structure of a technological system: lessons from UK retail banking
No full textThis article investigates the factors that have induced and shaped the process of industry evolution of banking in the United Kingdom and, in particular, the reorganization of the retail payments system. It will look at how the effects of technical progress within a changing regulatory framework have contributed to the flourishing of new consumer services, of increasingly specialized technologies and of new models of business organization. In relation to these issues, the paper develops an interpretative framework based on the rapidly expanding body of literature on technological systems. In so doing it argues also that the organization of the payment system has evolved towards a multilayered and increasingly heterogeneous industry in which competition has been fuelled at different levels by the growing diversity of the ecology of agents involved, as well as by the emerging patterns of interaction across them.
Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition
No full textWe present experimental results at intensities relevant to Shock Ignition obtained at the sub-ns Prague Asterix Laser System in 2012. We studied shock waves produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at 1ω (1315 nm) at 7 x 1013 W/cm2 to create a pre-plasma on the front side of the target and a second at 3ω (438 nm) at ∼ 1016 W/cm2 to create the shock wave. Multilayer targets composed of 25 (or 40 m) of plastic (doped with Cl), 5 m of Cu (for K diagnostics) and 20 m of Al for shock measurement were used. We used X-ray spectroscopy of Cl to evaluate the plasma temperature, K imaging and spectroscopy to evaluate spatial and spectral properties of the fast electrons and a streak camera for shock breakout measurements. Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and Two Plasmon Decay) were studied by collecting the back scattered light and analysing its spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum pressure reached in our experiment we performed hydro simulations with CHIC and DUED codes. The maximum shock pressure generated in our experiment at the front side of the target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV. © Published under licence by IOP Publishing Ltd
Changing boundaries and structure of a technological system: lessons from UK retail banking
No full textThis article investigates the factors that have induced and shaped the process of industry evolution of banking in the United Kingdom and, in particular, the reorganization of the retail payments system. It will look at how the effects of technical progress within a changing regulatory framework have contributed to the flourishing of new consumer services, of increasingly specialized technologies and of new models of business organization. In relation to these issues, the paper develops an interpretative framework based on the rapidly expanding body of literature on technological systems. In so doing it argues also that the organization of the payment system has evolved towards a multilayered and increasingly heterogeneous industry in which competition has been fuelled at different levels by the growing diversity of the ecology of agents involved, as well as by the emerging patterns of interaction across them.
Recent results from experimental studies on laser-plasma coupling in a shock ignition relevant regime
No full textShock ignition (SI) is an appealing approach in the inertial confinement scenario for the ignition and burn of a pre-compressed fusion pellet. In this scheme, a strong converging shock is launched by laser irradiation at an intensity Iλ2 > 1015 W cm-2 μm2 at the end of the compression phase. In this intensity regime, laser-plasma interactions are characterized by the onset of a variety of instabilities, including stimulated Raman scattering, Brillouin scattering and the two plasmon decay, accompanied by the generation of a population of fast electrons. The effect of the fast electrons on the efficiency of the shock wave production is investigated in a series of dedicated experiments at the Prague Asterix Laser Facility (PALS). We study the laser-plasma coupling in a SI relevant regime in a planar geometry by creating an extended preformed plasma with a laser beam at ∼7 × 1013 W cm-2 (250 ps, 1315 nm). A strong shock is launched by irradiation with a second laser beam at intensities in the range 1015-1016 W cm-2 (250 ps, 438 nm) at various delays with respect to the first beam. The pre-plasma is characterized using x-ray spectroscopy, ion diagnostics and interferometry. Spectroscopy and calorimetry of the backscattered radiation is performed in the spectral range 250-850 nm, including (3/2)ω, ω and ω/2 emission. The fast electron production is characterized through spectroscopy and imaging of the Kα emission. Information on the shock pressure is obtained using shock breakout chronometry and measurements of the craters produced by the shock in a massive target. Preliminary results show that the backscattered energy is in the range 3-15%, mainly due to backscattered light at the laser wavelength (438 nm), which increases with increasing the delay between the two laser beams. The values of the peak shock pressures inferred from the shock breakout times are lower than expected from 2D numerical simulations. The same simulations reveal that the 2D effects play a major role in these experiments, with the laser spot size comparable with the distance between critical and ablation layers. © 2013 IOP Publishing Ltd
Low-noise time-resolved optical sensing of electromagnetic pulses from petawatt laser-matter interactions
No full textWe report on the development and deployment of an optical diagnostic for single-shot measurement of the electric-field components of electromagnetic pulses from high-intensity laser-matter interactions in a high-noise environment. The electro-optic Pockels effect in KDP crystals was used to measure transient electric fields using a geometry easily modifiable for magnetic field detection via Faraday rotation. Using dielectric sensors and an optical fibre-based readout ensures minimal field perturbations compared to conductive probes and greatly limits unwanted electrical pickup between probe and recording system. The device was tested at the Vulcan Petawatt facility with 1020 W cm-2 peak intensities, the first time such a diagnostic has been used in this regime. The probe crystals were located ~1.25 m from target and did not require direct view of the source plasma. The measured signals compare favourably with previously reported studies from Vulcan, in terms of the maximum measured intra-crystal field of 10.9 kV/m, signal duration and detected frequency content which was found to match the interaction chamber's horizontal-plane fundamental harmonics of 76 and 101 MHz. Methods for improving the diagnostic for future use are also discussed in detail. Orthogonal optical probes offer a low-noise alternative for direct simultaneous measurement of each vector field component. © 2017 The Author(s)
A laser application to nuclear astrophysics
No full textIn the last decade, the availability in high-intensity laser beams capable of producing plasmas with ion energies large enough to induce nuclear reactions has opened new research paths in nuclear physics. We studied the reactions 3He(d, p)4He and d(d,n)3He at temperatures of few keV in a plasma, generated by the interaction of intense ultrafast laser pulses with molecular deuterium or deuterated-methane clusters mixed with 3He atoms. The yield of 14.7 MeV protons from the 3He(d, p)4He reaction was used to extract the astrophysical S factor. Results of the experiment performed at the Center for High Energy Density Science at The University of Texas at Austin will be presented. © 2014 AIP Publishing LLC
L'evoluzione delle relazioni industriali nel posto di lavoro in un contesto di globalizzazione: una survey internazionale nel settore elettronico ed elettromeccanico
No full textRivista Sociologia del Lavor
Parkinson Disease Genetics: A “Continuum” from Mendelian to Multifactorial Inheritance
No full textParkinson Disease (PD) is a common neurodegenerative disorder of intricate etiology, caused by progressive loss of aminergic neurons and accumulation of Lewy bodies. The predominant role of genetics in the etiology of the disease has emerged since the identification of the first pathogenetic mutation in SNCA (alpha-synuclein) gene, back in 1997. Mendelian parkinsonisms, a minority among all PD forms, have been deeply investigated, with 19 loci identified. More recently, genome wide association studies have provided convincing evidence that variants in some of these genes, as well as in other genes, may confer an increased risk for late onset, sporadic PD. Moreover, the finding that heterozygous mutations in the GBA gene (mutated in Gaucher disease) are among the strongest genetic susceptibility factors for PD, has widened the scenario of PD genetic background to enclose a number of genes previously associated to distinct disorders, such as genes causative of spinocerebellar ataxias, mitochondrial disorders and fragile X syndrome. At present, the genetic basis of PD defines a continuum from purely mendelian forms (such as those caused by autosomal recessive genes) to multifactorial inheritance, resulting from the variable interplay of many distinct genetic variants and environmental factors
CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification
No full textLaser-accelerated ion beams can be used in many applications and, especially, to initiate nuclear reactions out of thermal equilibrium. We have experimentally studied aneutronic fusion reactions induced by protons accelerated by the Target Normal Sheath Acceleration mechanism, colliding with a boron target. Such experiments require a rigorous method to identify the reaction products (alpha particles) collected in detectors among a few other ion species such as protons or carbon ions, for example. CR-39 track detectors are widely used because they are mostly sensitive to ions and their efficiency is near 100%. We present a complete calibration of CR-39 track detector for protons, alpha particles, and carbon ions. We give measurements of their track diameters for energy ranging from hundreds of keV to a few MeV and for etching times between 1 and 8 h. We used these results to identify alpha particles in our experiments on proton-boron fusion reactions initiated by laser-accelerated protons. We show that their number clearly increases when the boron fuel is preformed in a plasma state. © 2015 AIP Publishing LLC
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