410 research outputs found

    Electromagnetic Transients on Power Plant Connection Caused by Lightning Event

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    Lightning events can seriously damage the power systems and they represent one of the most dangerous causes of faults in the transmission lines. Usually, when one want to analyze such effects it is necessary to rely on approximate models or to simplify in some ways the power system. As a consequence, an overall analysis taking into account the complexity of the power system is difficult to find. This paper presents the study of the electromagnetic transients caused by lightning events in a point of connection between a real power plant and a large power grid. The analysis is achieved with a high level of details of the power system and the simulations are obtained through an EMT-type software (PSCAD-EMTDC). Different simulations are analyzed, showing how the cables and the transformers are affected by the electromagnetic transients

    The effects of robotic assistance on upper limb spatial muscle synergies in healthy people during planar upper-limb training

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    Background Robotic rehabilitation is a commonly adopted technique used to restore motor functionality of neurological patients. However, despite promising results were achieved, the effects of human-robot interaction on human motor control and the recovery mechanisms induced with robot assistance can be further investigated even on healthy subjects before translating to clinical practice. In this study, we adopt a standard paradigm for upper-limb rehabilitation (a planar device with assistive control) with linear and challenging curvilinear trajectories to investigate the effect of the assistance in human-robot interaction in healthy people. Methods Ten healthy subjects were instructed to perform a large set of radial and curvilinear movements in two interaction modes: 1) free movement (subjects hold the robot handle with no assistance) and 2) assisted movement (with a force tunnel assistance paradigm). Kinematics and EMGs from representative upper-limb muscles were recorded to extract phasic muscle synergies. The free and assisted interaction modes were compared assessing the level of assistance, error, and muscle synergy comparison between the two interaction modes. Results It was found that in free movement error magnitude is higher than with assistance, proving that task complexity required assistance also on healthy controls. Moreover, curvilinear tasks require more assistance than standard radial paths and error is higher. Interestingly, while assistance improved task performance, we found only a slight modification of phasic synergies when comparing assisted and free movement. Conclusions We found that on healthy people, the effect of assistance was significant on task performance, but limited on muscle synergies. The findings of this study can find applications for assessing human-robot interaction and to design training to maximize motor recovery

    Lightning in Western Patagonia

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    On the basis of 8 years (2005-2012) of stroke data from the World Wide Lightning Location Network we describe the spatial distribution and temporal variability of lightning activity over Western Patagonia. This region extends from ~40°S to 55°S along the west coast of South America, is limited to the east by the austral Andes, and features a hyper-humid, maritime climate. Stroke density exhibits a sharp maximum along the coast of southern Chile. Although precipitation there is largely produced by cold nimbostratus, days with more than one stroke occur up to a third of the time somewhere along the coastal strip. Disperse strokes are also observed off southern Chile. In contrast, strokes are virtually nonexistent over the austral Andes -where precipitation is maximum- and farther east over the dry lowlands of Argentina. Atmospheric reanalysis and satellite imagery are used to characterize the synoptic environment of lightning-producing storms, exemplified by a case study and generalized by a compositing analysis. Lightning activity tends to occur when Western Patagonia is immersed in a pool of cold air behind a front that has reached the coast at ~40°S. Under these circumstances, midlevel cooling occurs before and is more prominent than near-surface cooling, leading to a weakly unstable postfrontal condition. Forced uplift of the strong westerlies impinging on the coastal mountains can trigger convection and produces significant lightning activity in this zone. Farther offshore, large-scale ascent near the cyclone's center may lift near-surface air parcels, fostering shallow convection and dispersing lightning activity.publishedVersionFil: Bürgesser, Rodrigo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Ávila, Eldo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Bürgesser, Rodrigo E. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ávila, Eldo E. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Garreaud, René D. Universidad de Chile. Department of Geophysics and Center for Climate and Resilience Research; ChileFil: Nicora, M. Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Fil: Nicora, M. Gabriela. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Meteorología y Ciencias Atmosférica

    Lightning activity in the Southern Coast of Chile

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    Ponencia presentada en la XV International Conference on Atmospheric Electricity, 15-20 June 2014, Norman, Oklahoma, U.S.A.Based on eight years of lightning data (from January 2005 to December 2012) from the World Wide Lightning Location Network (WWLLN) we describe the spatial distribution and temporal variability of lightning activity over southern Chile. This region extends from ~ 40°S to 55°S along the west coast of South America, is limited to the east by the austral Andes about 100 km inland, and features a maritime climate with annual mean precipitation in excess of 4000 mm. Cloud electrification is not expected in this region given the predominance of stable, deep-stratiform precipitation there, but days with at least one stroke occur up to a third of the time along the coast, being slightly more frequent during late summer and fall. Lightning density and frequency of lightning days exhibit a sharp maximum along the coast of southern Chile. Disperse strokes are also observed off southern Chile. In contrast, lightning activity is virtually inexistent over the austral Andes -where precipitation is maximum- and farther east over the dry lowlands of Argentina. It is suggested that electrification could develop under weakly unstable conditions that prevail in the region after the passage of a cold front. Large-scale ascent near the cyclone?s center may lift near-surface air parcels over open ocean fostering shallow convection, which is enhanced as the strong westerly flow ascend over the coastal topography. Laboratory experiments of charge transferred during ice crystal-graupel collisions in low liquid water content conditions and low impact velocity have shown that the non-inductive mechanism can work as a charge separation process in these systems.Fil: Nicora, M. Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Fil: Nicora, M. Gabriela. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Fil: Quel, Eduardo J. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Fil: Quel, Eduardo J. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Departamento de Investigaciones en Láseres y sus aplicaciones; Argentina.Fil: Bürgesser, Rodrigo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Bürgesser, Rodrigo E. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ávila, Eldo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Ávila, Eldo E. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Garreaud, René D. Universidad de Chile. Department of Geophysics; ChileFil: Garreaud, René D. Center for Climate and Resilience Research; ChileInvestigación Climatológic

    Magnetostratigraphy and biostratigraphy of the Carnian/Norian boundary interval from the Pizzo Mondello section (Sicani Mountains, Sicily)

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    The 146.5 m-thick Upper Triassic limestone section at Pizzo Mondello in the Sicani Mountains of western Sicily is characterized by high quality of exposure, accessibility, and stratigraphic continuity. Magnetostratigraphic results delineate 12 normal and reverse polarity magnetozones, labelled successively from the base upwards as PM1n, PM1r, PM6n, PM6r. The Carnian/Norian boundary, based on conodont biostratigraphy, falls somewhere in the PM3n to PM5n interval which corresponds to the E14n to E16n magnetozone interval in the Newark reference sequence of polarity reversals. Comparison of magnetobiostratigraphic data from the Newark basin, Pizzo Mondello and other Late Triassic marine sections available from the literature suggests the existence of a reduction in sedimentation rate in the Tethyan marine domain at around the Carnian/Norian boundary. Although the Newark and the expanded Pizzo Mondello sections correlate well with each other, correlation with the condensed Kavur Tepe and Scheiblkogel sections is unsatisfactory. A re-interpretation of the Kavur Tepe results suggests that the section is younger than its previous correlation with the Newark section, and that it was deposited in the northern instead of the southern hemisphere. Most of the condensed Tethyan marine sections are seen to be highly discontinuous, as evidenced by concantenated conodont total range zones

    Anatomy of carbonate mounds from the Middle Anisian of Nakhlak (Central Iran): architecture and age of a subtidal microbial-bioclastic carbonate factory

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    The Anisian succession of Nakhlak (in Central Iran) is characterized by a siliciclastic succession with minor carbonate units, with massive carbonate mounds up to 50 m thick in its upper part. The mounds, constrained in age to the late Bithynian (Ismidicus Zone) by ammonoids and conodonts, are characterized by a flat top and a lateral pinch-out marked by clinostratified slopes (about 15A degrees in dip). Stratigraphic and microfacies analyses document an inner part of the mound characterized by massive microbial carbonates with open-space structures (stromatactis) filled with fine-grained internal sediments and marine cements. Isolated sponges (up to 5 cm), serpulids and bryozoans are present, which grew on the calcimicrobial limestone. A narrow bioclastic margin (mainly with crinoids and brachiopods) produces most of the slope facies (consisting of bioclastic grainstone and packstone, with intraclasts from the inner part of the mounds) which interfinger basinward with volcaniclastic sandstones. The demise of carbonate productivity is marked on the top of the carbonate mounds by a condensed surface, rich in ammonoids, glaucony grains, and articulated crinoids, documenting a rapid drowning. Paleolatitude data support deposition in a tropical setting, and sedimentological constraints indicate deposition close to the fair-weather wave base, within the photic zone. The late Bithynian Nakhlak carbonate mounds developed before the appearance (documented since the Pelsonian in different parts of the world) of scleractinians which, despite the favorable environmental conditions, are absent at Nakhlak. The Nakhlak mounds thus represent one of the last occurrences of the microbial factories (which developed after the Permo-Triassic extinction event and persisted for most of the Middle Triassic, but with a gradually increasing role played by scleractinians) before the first appearance of the Mesozoic corals

    Urinary virome perturbations in kidney transplantation

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    The human microbiome is important for health and plays a role in essential metabolic functions and protection from certain pathogens. Conversely, dysbiosis of the microbiome is seen in the context of various diseases. Recent studies have highlighted that a complex microbial community containing hundreds of bacteria colonizes the healthy urinary tract, but little is known about the human urinary viruses in health and disease. To evaluate the human urinary virome in the context of kidney transplantation (tx), variations in the composition of the urinary virome were evaluated in urine samples from normal healthy volunteers as well as patients with kidney disease after they had undergone kidney tx. Liquid chromatography-mass spectrometry/mass spectrometry analysis was undertaken on a selected cohort of 142 kidney tx patients and normal healthy controls, from a larger biobank of 770 kidney biopsy matched urine samples. In addition to analysis of normal healthy control urine, the cohort of kidney tx patients had biopsy confirmed phenotype classification, coincident with the urine sample analyzed, of stable grafts (STA), acute rejection, BK virus nephritis, and chronic allograft nephropathy. We identified 37 unique viruses, 29 of which are being identified for the first time in human urine samples. The composition of the human urinary virome differs in health and kidney injury, and the distribution of viral proteins in the urinary tract may be further impacted by IS exposure, diet and environmental, dietary, or cutaneous exposure to various insecticides and pesticides

    Pain in cancer. An outcome research project to evaluate the epidemiology, the quality and the effects of pain treatment in cancer patients

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    BACKGROUND: Management of pain related to advanced or metastatic cancer, although the availability of several pharmacological and non-pharmacological interventions and the existence of well-known guidelines and protocols, is often difficult and inadequate. Evidence of the relative effectiveness of current options for treating cancer pain from comparative randomized studies is scanty. METHODS: In the context of a wider project, a multicenter, open label, prospective Outcome Research study will be launched in Italy in 2006 to investigate the epidemiology of cancer pain and of its treatments, the quality of analgesic-drug therapy and the effectiveness of alternative analgesic strategies in a large, prospective, unselected cohort of cancer patients using the state-of-the art of patient-reported-outcomes. About 100 Italian centers will recruit 2500 patients with advanced/progressive/metastatic cancer with pain (related to the cancer disease) requiring analgesic treatments. Each center is expected to recruit 25 consecutive and eligible patients during the study inception period. Approximately two months will be allowed for subject recruitment and enrollment. Subject evaluation and follow-up will be for 3 months. The effect on outcomes of various therapeutic analgesic options administered by physicians, given the observational approach where patients are not assigned at random to different treatments, will be compared using the propensity score approach, allowing the adjustment for treatment selection bias. Later, after the launch of the observational study and on the basis of results, in specific subsamples of patients and in select centers of the network, a Randomized Controlled Trial will be carried out to formally compare the efficacy of alternative analgesic strategies, with particular emphasis on oral morphine (as comparator) and buprenorphine patch (as experimental arm). Results from the outcome (cohort) and experimental (Randomized Controlled Trial) studies will ensure both the external and internal validity

    Perturbations in the Urinary Exosome in Transplant Rejection

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    Urine exosomes are small vesicles exocytosed into the urine by all renal epithelial cell types under normal physiologic and disease states. Urine exosomal proteins may mirror disease specific proteome perturbations in kidney injury. Analysis methodologies for the exosomal fraction of the urinary proteome were developed for comparing the urinary exosomal fraction versus unfractionated proteome for biomarker discovery. Urine exosomes were isolated by centrifugal filtration of urine samples collected from kidney transplant patients with and without acute rejection, which were biopsy matched. The proteomes of unfractionated whole urine (Uw) and urine exosomes (Ue) underwent mass spectroscopy-based quantitative proteonomics analysis. The proteome data were analyzed for significant differential protein abundances in acute rejection (AR). A total of 1018 proteins were identified in Uw and 349 proteins in Ue. 279 overlapped between the two urinary compartments and 70 proteins were unique to the Ue compartment. Of 349 exosomal proteins identified from transplant patients,220 had not been previously identified in the normal Ue fraction. 11 Ue proteins, functionally involved in an inflammatory and stress response, were more abundant in urine samples from patients with acute rejection, 3 of which are exclusive to the Ue fraction. Ue AR-specific biomarkers(8) were also detected in Uw, but since they were observed at significantly lower abundances in Uw, they were not significant for AR in Uw. A rapid urinary exosome isolation method and quantitative measurement of enriched Ue proteins was applied. Perturbed proteins in the exosomal compartment of urine collected from kidney transplant patients were specific to inflammatory responses, and were not observed in the Ue fraction from normal healthy subjects. Ue specific protein alterations in renal disease provide potential mechanistic insights and offer a unique panel of sensitive biomarkers for monitoring AR
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