840 research outputs found

    Fiber Bragg Grating sensors for deformation monitoring of GEM foils in HEP detectors

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    Fiber Bragg Grating (FBG) sensors have been so far mainly used in high energy physics (HEP) as high precision positioning and re-positioning sensors and as low cost, easy to mount, radiation hard and low space- consuming temperature and humidity devices. FBGs are also commonly used for very precise strain measurements. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide Gas Electron Multiplier (GEM) foils of the GE1/1 chambers of the Compact Muon Solenoid (CMS) experiment at Large Hadron Collider (LHC) of CERN. A network of FBG sensors has been used to determine the optimal mechanical tension applied and to characterize the mechanical stress applied to the foils. The preliminary results of the test performed on a full size GE1/1 final prototype and possible future developments will be discussed.Comment: Four pages, seven figures. Presented by Michele Caponero at IWASI 2015, Gallipoli (Italy

    A Machine Learning Tool for Interpreting Differences in Cognition Using Brain Features

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    Predicting variability in cognition traits is an attractive and challenging area of research, where different approaches and datasets have been implemented with mixed results. Some powerful Machine Learning algorithms employed before are difficult to interpret, while other algorithms are easy to interpret but might not be as powerful. To improve understanding of individual cognitive differences in humans, we make use of the most recent developments in Machine Learning in which powerful prediction models can be interpreted with confidence. We used neuroimaging data and a variety of behavioural, cognitive, affective and health measures from 905 people obtained from the Human Connectome Project (HCP). As a main contribution of this paper, we show how one could interpret the neuroanatomical basis of cognition, with recent methods which we believe are not yet fully explored in the field. By reducing neuroimages to a well characterised set of features generated from surface-based morphometry and cortical myelin estimates, we make the interpretation of such models easier as each feature is self-explanatory. The code used in this tool is available in a public repository: https://github.com/tjiagoM/interpreting-cognition-paper-2019

    Eco-friendly gas mixtures for Resistive Plate Chambers based on Tetrafluoropropene and Helium

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    Due to the recent restrictions deriving from the application of the Kyoto protocol, the main components of the gas mixtures presently used in the Resistive Plate Chambers systems of the LHC experiments will be most probably phased out of production in the coming years. Identifying possible replacements with the adequate characteristics requires an intense R&D, which was recently started, also in collaborations across the various experiments. Possible candidates have been proposed and are thoroughly investigated. Some tests on one of the most promising candidate - HFO-1234ze, an allotropic form of tetrafluoropropane- have already been reported. Here an innovative approach, based on the use of Helium, to solve the problems related to the too elevate operating voltage of HFO-1234ze based gas mixtures, is discussed and the relative first results are shown.Comment: 9 pages, 6 figures, 1 tabl

    Psychopathic traits influence amygdala-anterior cingulate cortex connectivity during facial emotion processing

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    There is accumulating evidence that youths with antisocial behavior or psychopathic traits show deficits in facial emotion recognition, but little is known about the neural mechanisms underlying these impairments. A number of neuroimaging studies have investigated brain activity during facial emotion processing in youths with Conduct Disorder (CD) and adults with psychopathy, but few of these studies tested for group differences in effective connectivity – i.e., changes in connectivity during emotion processing. Using functional magnetic resonance imaging and psycho-physiological interaction methods, we investigated the impact of CD and psychopathic traits on amygdala activity and effective connectivity in 46 male youths with CD and 25 typically-developing controls when processing emotional faces. All participants were aged 16-21 years. Relative to controls, youths with CD showed reduced amygdala activity when processing angry or sad faces relative to neutral faces, but the groups did not significantly differ in amygdala-related effective connectivity. In contrast, psychopathic traits were negatively correlated with amygdala-ventral anterior cingulate cortex connectivity for angry versus neutral faces, but were unrelated to amygdala responses to angry or sad faces. These findings suggest that CD and psychopathic traits have differential effects on amygdala activation and functional interactions between limbic regions during facial emotion processing

    The central autonomic network at rest: Uncovering functional MRI correlates of time-varying autonomic outflow.

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    Peripheral measures of autonomic nervous system (ANS) activity at rest have been extensively employed as putative biomarkers of autonomic cardiac control. However, a comprehensive characterization of the brain-based central autonomic network (CAN) sustaining cardiovascular oscillations at rest is missing, limiting the interpretability of these ANS measures as biomarkers of cardiac control. We evaluated combined cardiac and fMRI data from 34 healthy subjects from the Human Connectome Project to detect brain areas functionally linked to cardiovagal modulation at rest. Specifically, we combined voxel-wise fMRI analysis with instantaneous heartbeat and spectral estimates obtained from inhomogeneous linear point-process models. We found exclusively negative associations between cardiac parasympathetic activity at rest and a widespread network including bilateral anterior insulae, right dorsal middle and left posterior insula, right parietal operculum, bilateral medial dorsal and ventrolateral posterior thalamic nuclei, anterior and posterior mid-cingulate cortex, medial frontal gyrus/pre-supplementary motor area. Conversely, we found only positive associations between instantaneous heart rate and brain activity in areas including frontopolar cortex, dorsomedial prefrontal cortex, anterior, middle and posterior cingulate cortices, superior frontal gyrus, and precuneus. Taken together, our data suggests a much wider involvement of diverse brain areas in the CAN at rest than previously thought, which could reflect a differential (both spatially and directionally) CAN activation according to the underlying task. Our insight into CAN activity at rest also allows the investigation of its impairment in clinical populations in which task-based fMRI is difficult to obtain (e.g., comatose patients or infants).This work was supported by the US National Institutes for Health (NIH), Office of the Director (OT2-OD023867 to VN); National Center for Complementary and Integrative Health (NCCIH), NIH (P01-AT009965, R61-AT009306, R33-AT009306, R01-AT007550 to VN); the National Institute for Arthritis and Musculoskeletal and Skin Diseases (NIAMS), NIH (R01-AR064367 to VN); the Medical Research Council (MRC), UK (MR/P01271X/1 to LP); the American Heart Association (16GRNT26420084 to RB)

    Confinement of Monolithic Stationary Phases in Targeted Regions of 3D-Printed Titanium Devices Using Thermal Polymerization

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    Abstract In this study, we have prepared thermally initiated polymeric monolithic stationary phases within discrete regions of 3D-printed titanium devices. The devices were created with controllable hot and cold regions. The monolithic stationary phases were first locally created in capillaries inserted into the channels of the titanium devices. The homogeneity of the monolith structure and the interface length were studied by scanning a capacitively coupled conductivity contactless detector (C4D) along the length of the capillary. Homogeneous monolithic structures could be obtained within a titanium device equipped with a hot and cold jacket connected to two water baths. The confinement method was optimized in capillaries. The sharpest interfaces (between monolith and empty channel) were obtained with the hot region maintained at 70 °C and the cold region at 4 or 10 °C, with the latter temperature yielding better repeatability. The optimized conditions were used to create monoliths bound directly to the walls of the titanium channels. The fabricated monoliths were successfully used to separate a mixture of four intact proteins using reversed-phase liquid chromatography. Further chromatographic characterization showed a permeability (Kf) of ∼4 × 10–15 m2 and a total porosity of 60%. Since their introduction in the chromatographic world, porous polymer monoliths have proven to be powerful separation media. These chromatographic supports have been widely applied for applications, such as microscale liquid chromatography (LC) of peptides and proteins, but have also been used in capillary electrochromatography (CEC),(1) gas chromatography (GC),(2) sample preparation,(3) and catalysis.(4) The ease of preparation of monoliths, diverse chemistry options, and high permeabilities have made them popular materials for analytical devices, such as microfluidic chips for LC. In the past decade, miniaturization has been realized by developing lab-on-a-chip solutions, where several analytical processes can be integrated within a few square centimeters. In such systems, due to the small channels and articulated geometries, the particle-packing procedure has proven to be challenging.(5) In contrast, monolithic beds are usually created in situ by free-radical polymerization of monomers in the presence of porogens and they are well-suited for chip-based separations. The proliferation of microfluidic devices has spurred new interest in polymer monoliths for applications such as enzymatic reactors(6,7) and microfluidic mixers.(8) This development has been boosted by the advent of additive manufacturing (or 3D-printing), which allows for rapid prototyping of complex structures, converting computer-aided-design (CAD) models into physical objects. Unfortunately, the use of 3D-printed analytical devices for chromatographic analysis is limited by the solvent compatibility of some materials (e.g., acrylate-based polymers) and in some cases by their transparency at the desired wavelength (e.g., UV or IR wavelengths). Several successful steps have been taken to locally photopolymerize monolithic stationary phases in discrete regions of microfluidic devices.(9−12) Heat is an alternative way to transfer energy to the monomer precursors for initiating the polymerization. However, accurate control of temperature in small confined spaces is more difficult to achieve, and so far only few steps have been taken in this direction.(13) In this work, two methods are explored to achieve confined thermal polymerization. The first approach involves direct contact (DC) between Peltier elements and the surface of a titanium device. In the second approach, recirculating jackets are used for localized heating and cooling (heating/cooling jackets, HCJ). The latter approach resembles a recirculation-based freeze–thaw valve.(14) In both approaches, defined hot (HR) and cold (CR) regions are created. We aim to fabricate poly(styrene-co-divinylbenzene) (PS-DVB) monolithic stationary phases within a 3D-printed titanium microfluidic device through polymerization at 70 °C, and to separate intact proteins using this device
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