1,653 research outputs found

    Gyrification, cortical and subcortical morphometry in neurofibromatosis type 1: an uneven profile of developmental abnormalities.

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    Background: Neurofibromatosis type 1 (NF1) is a monogenic disorder associated with cognitive impairments. In order to understand how mutations in the NF1 gene impact brain structure it is essential to characterize in detail the brain structural abnormalities in patients with NF1. Previous studies have reported contradictory findings and have focused only on volumetric measurements. Here, we investigated the volumes of subcortical structures and the composite dimensions of the cortex through analysis of cortical volume, cortical thickness, cortical surface area and gyrification. Methods: We studied 14 children with NF1 and 14 typically developing children matched for age, gender, IQ and right/left-handedness. Regional subcortical volumes and cortical gyral measurements were obtained using the FreeSurfer software. Between-group differences were evaluated while controlling for the increase in total intracranial volume observed in NF1. Results: Subcortical analysis revealed disproportionately larger thalami, right caudate and middle corpus callosum in patients with NF1. Cortical analyses on volume, thickness and surface area were however not indicative of significant alterations in patients. Interestingly, patients with NF1 had significantly lower gyrification indices than typically developing children primarily in the frontal and temporal lobes, but also affecting the insula, cingulate cortex, parietal and occipital regions. Conclusions: The neuroanatomic abnormalities observed were localized to specific brain regions, indicating that particular areas might constitute selective targets for NF1 gene mutations. Furthermore, the lower gyrification indices were accompanied by a disproportionate increase in brain size without the corresponding increase in folding in patients with NF1. Taken together these findings suggest that specific neurodevelopmental processes, such as gyrification, are more vulnerable to NF1 dysfunction than others. The identified changes in brain organization are consistent with the patterns of cognitive dysfunction in the NF1 phenotype. © 2013 Violante et al

    Acoustics for Marine Surveys

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    SONAR is an acronym for (So)und (Na)vigation and (R)anging. Sound waves have a physical character that differs from that of other types of propagating waves, i.e. light and radio waves. Sound and acoustic are terms that can be used interchangeably, although the latter is a broader term. The former is most often used to describe acoustic frequencies within the range of human hearing, which leads to terms like ultrasonic and sub-sonic for acoustic frequencies that are respectively, above and below the range of human hearing. Acoustic waves are based on vibrations of the actual material of the medium and are manifested as periodic variations of pressure in the medium. As a result of this physical nature of acoustic waves, the exact composition of the material through which an acoustic wave travels will impact the energy that is necessarily lost as the wave propagates through the material. When a propagating acoustic wave encounters a sudden change in the properties (sound speed and/or density, but specifically the product of sound speed and density) of the actual material of the medium, a portion of the acoustic wave will change its propagation direction. That portion of the acoustic wave that reverses its propagation direction is the echo which echo sounders are designed to exploit for distance measurements. If the transmission/reception of acoustic energy can be confined to a singular narrow angular sector, the detection of an echo at some time after a pulse is transmitted provides both the range and bearing to the point in space where the echo was generated. Measuring the local configuration of the seabed with acoustics is that basic: transmit acoustic energy toward the bottom and detect the arrival times and directions of the acoustic energy that returns from the bottom. The measured ranges and 3-dimensional directions to points where the echoes were generated can be converted into 3-dimensional locations, relative to the transducer. Finally it is necessary to transfer the echo generation locations from the transducer frame of reference into the ship’s frame of reference and finally into the appropriate reference frame for presenting the survey results

    Towards Vehicle-Level Simulator Aided Failure Mode, Effect, and Diagnostic Analysis of Automotive Power Electronics Items

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    The increasing demand for Electronic Control Units able to perform safety-relevant tasks leads the automotive industry to find novel verification methodologies, capable to decrease the time-to-market and, at the same time, to improve the quality of the assessment. The ISO26262:2018 automotive functional safety standard requires to follow a strict development process, compliant with its “safety lifecycle”. It includes all the phases of the item life, from the concept to the decommissioning. The phase that places most difficulties about its objectivity and repeatability is the hardware/software integration verification since, usually, the software is in charge to mitigate the effects of some possible hardware failures. This paper proposes a novel technique, based on a simulation-based approach, to aid the designers during the Failure Mode, Effect, and Diagnostic Analysis (FMEDA). We consider a power electronics module, to be embedded into electric vehicles powertrains, as a challenging practical example. We performed some tests on it, considering a rear traction car with two independent electric motors, one per each wheel. This system, to allow the vehicle to curve, has to act like a differential gear. Hence, it has a strong safety impact on the driveability of the car. All the involved components have been simulated propagating their behaviours up to the entire vehicle. Due the strong coupling between item failures and vehicle dynamics, a structured way based on coupling fault injection with vehicle dynamic simulation is desirable

    Search for Neutron Flux Generation in a Plasma Discharge Electrolytic Cell

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    Following some recent unexpected hints of neutron production in setups like high-voltage atmospheric discharges and plasma discharges in electrolytic cells, we present a measurement of the neutron flux in a configuration similar to the latter. We use two different types of neutron detectors, poly-allyl-diglicol-carbonate (PADC, aka CR-39) tracers and Indium disks. At 95% C.L. we provide an upper limit of 1.5 neutrons cm^-2 s^-1 for the thermal neutron flux at ~5 cm from the center of the cell. Allowing for a higher energy neutron component the largest allowed flux is 64 neutrons cm^-2 s^-1. This upper limit is two orders of magnitude smaller than what previously claimed in an electrolytic cell plasma discharge experiment. Furthermore the behavior of the CR-39 is discussed to point our possible sources of spurious signals.Comment: 4 pages, 3 figure

    Flood Historical Data for Flood Risk Estimation in Coastal Areas, Eastern Tyrrhenian Sea, Italy

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    A reconstruction of historical floods occurred along the Amalfi coast, during the last five 7 centuries is presented. The analysis of historical sources allowed to achieve a chronological 8 reconstruction of more than 100 floods, four of which classified as catastrophic events. In this 9 task, the level of information was decisive to carry out space–time identification, estimate the 10 affected area and define the type of damage to the structures, and the environment (e.g. mud 11 flow, debris flow, rock falls, shoreline progradation, fan deltas), which may be relevant for the 12 recognition of similar events within the geologic record. The magnitude of the events was 13 finally estimated, taking into account the size of the areas affected by flooding as well as the 14 type of effects induced on the urban and physical environment and the recurrence intervals

    Improving safety through non-technical skills in chemical plants: The validity of a questionnaire for the self-assessment of workers

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    This research is aimed at developing a questionnaire for the self-assessment of non-technical skills (NTS) leading to safety in the chemical sector and at analysing the properties of its scales in terms of construct validity. The research involved 269 Italian employees from three chemical plants of an international company, who occupied low\u2013medium levels in the organizational hierarchy. Results showed a good level of validity and reliability of the instrument and suggested that communication, situational awareness, decision-making, and fatigue/stress management are the four most important NTS for safety in the chemical sector

    MOBILITY AND BIOAVAILABILITY OF HEAVY METALS AND METALLOIDS IN SOIL ENVIRONMENTS

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    In soil environments, sorption/desorption reactions as well as chemical complexation with inorganic and organic ligands and redox reactions, both biotic and abiotic, are of great importance in controlling their bioavailability, leaching and toxicity. These reactions are affected by many factors such as pH, nature of the sorbents, presence and concentration of organic and inorganic ligands, including humic and fulvic acid, root exudates, microbial metabolites and nutrients. In this review, we highlight the impact of physical, chemical, and biological interfacial interactions on bioavailability and mobility of metals and metalloids in soil. Special attention is devoted to: i) the sorption/desorption processes of metals and metalloids on/from soil components and soils; ii) their precipitation and reduction-oxidation reactions in solution and onto surfaces of soil components; iii) their chemical speciation, fractionation and bioavailability

    Inhaled CO2 Concentration While Wearing Face Masks: A Pilot Study Using Capnography

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    Background: Face masks are recommended based on the assumption that they protect against SARS-CoV-2 transmission, however studies on their potential side effects are still lacking. We aimed to evaluate the inhaled air carbon dioxide (CO2) concentration, when wearing masks. Methods: We measured end-tidal CO2 using professional side-stream capnography, with water-removing tubing, (1) without masks, (2) wearing a surgical mask, and (3) wearing a FFP2 respirator (for 5 minutes each while seated after 10 minutes of rest), in 146 healthy volunteers aged 10 to 90 years, from the general population of Ferrara, Italy. The inhaled air CO2 concentration was computed as: ([mask volume × end-tidal CO2] + [tidal volume − mask volume] × ambient air CO2)/tidal volume. Results: With surgical masks, the mean CO2 concentration was 7091 ± 2491 ppm in children, 4835 ± 869 in adults, and 4379 ± 978 in the elderly. With FFP2 respirators, this concentration was 13 665 ± 3655 in children, 8502 ± 1859 in adults, and 9027 ± 1882 in the elderly. The proportion showing a CO2 concentration higher than the 5000 ppm (8-hour average) acceptable threshold for workers was 41.1% with surgical masks, and 99.3% with FFP2 respirators. Adjusting for age, gender, BMI, and smoking, the inhaled air CO2 concentration significantly increased with increasing respiratory rate (mean 10 837 ±3712 ppm among participants ⩾18 breaths/minute, with FFP2 respirators), and among the minors. Conclusion: If these results are confirmed, the current guidelines on mask-wearing should be reevaluated

    The geological record of storm events over the last 1000 years in the Salerno Bay (Southern Tyrrhenian Sea): new proxy evidences

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    International audienceThe shallow marine Late Holocene wedge of the northern Salerno Bay shelf (Southern Tyrrhenian Sea) discloses the presence of four decimetric shelf-tapering sand beds. Their internal features, depicted by cores analysis and their stratigraphic position, revealed by VHR seismic investigations, inferred sandy layers as being the result of flash deposition, storm controlled, thus episodic. Stratigraphic correlations among cores lead to constrain sandy layers deposition to storm events falling in the 11th, 16th, 19th and 20th centuries. A certain attribution of the most recent event bed to the major cloudburst that hit the Salerno region in 1954A.D. and resulted in a disastrous flood of the Bonea stream, was formerly achieved. A tentative link with two sea-storms that occurred in the 1544A.D. and in the 1879A.D. and well documented by historical sources is here proposed to explain the deposition of the two previous event beds. The deposition of these sandy layers must be related to major storm events, since their preservation in the stratigraphic record is not common. Lithostratigraphic and textural differences between flood and sea-storm emplacement emerge from the study of sandy layers in cores and point to a prevalence of sea-storm deposits in the middle shelf compared to flood deposits. Seismic stratigraphic evidence lead us to suppose that the style of episodic flash deposition has been running on for the last 2-3kyr and is probably linked to a climatic trend of the region
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