766 research outputs found

    MRI in Neurosciences

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    AC-coupled GaAs microstrip detectors with a new type of integrated bias resistors

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    Full size single-sided GaAs microstrip detectors with integrated coupling capacitors and bias resistors have been fabricated on 3'' substrate wafers. PECVD deposited SiO_2 and SiO_2/Si_3N_4 layers were used to provide coupling capacitaces of 32.5 pF/cm and 61.6 pF/cm, respectively. The resistors are made of sputtered CERMET using simple lift of technique. The sheet resistivity of 78 kOhm/sq. and the thermal coefficient of resistance of less than 4x10^-3 / degree C satisfy the demands of small area biasing resistors, working on a wide temperature range.Comment: 20 pages, 9 figures, to be published in NIM

    Meta-analysis of molecular imaging of serotonin transporters in ecstasy/polydrug users

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    We conducted a meta-analysis on the available data from studies investigating SERTs in ecstasy users and polydrug using controls. From 7 studies we compared data from 157 ecstasy users and 148 controls across 14 brain regions. The main effect suggested ecstasy/MDMA related SERT reductions (SMD = 0.52, 95% CIs [0.40, 0.65]; Z = 8.36, p < .01, I2 = 89%). A significant effect of subgroups (X2 = 37.41, df = 13, p < .01, I2 = 65.3%) suggested differential effects across brain ROIs. Ecstasy users showed significant SERT reductions in 11 out of the 14 regions, including every neocortical and limbic region analysed. Greatest effects were observed in the occipital cortex (SMD = 1.09, 95% CIs [0.70, 1.48]). No group effects were observed in subcortical areas of the caudate, putamen and midbrain. Literature on Postsynaptic 5HT2A receptor imaging was synthesised with these results. We conclude that, in line with preclinical data, serotonin axons with the longest projections from the raphe nuclei appear to be most affected by ecstasy/MDMA use

    Distributed optical fibre sensing in synthetic fibre ropes and cables

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    Distributed strain measurements on synthetic fibre ropes as used in marine applications are reported. The ropes incorporate single mode fibre-optic sensors for strain measurement. A Brillouin-amplification-based distributed strain measuring system has been utilised to interrogate the fibre sensors incorporated into a parallel yarn aramid rope. Initial results are presented to conclusively demonstrate the technical feasibility of the approach

    Cortical thickness is not associated with current depression in a clinical treatment study

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    BackgroundReduced cortical thickness is a candidate biological marker of depression, although findings are inconsistent. This could reflect analytic heterogeneity, such as use of region‐wise cortical thickness based on the Freesurfer Desikan–Killiany (DK) atlas or surface‐based morphometry (SBM). The Freesurfer Destrieux (DS) atlas (more, smaller regions) has not been utilized in depression studies. This could also reflect differential gender and age effects.MethodsCortical thickness was collected from 170 currently depressed adults and 52 never‐depressed adults. Visually inspected and approved Freesurfer‐generated surfaces were used to extract cortical thickness estimates according to the DK atlas (68 regions) and DS atlas (148 regions) for region‐wise analysis (216 total regions) and for SBM.ResultsOverall, except for small effects in a few regions, the two region‐wise approaches generally failed to discriminate depressed adults from nondepressed adults or current episode severity. Differential effects by age and gender were also rare and small in magnitude. Using SBM, depressed adults showed a significantly thicker cluster in the left supramarginal gyrus than nondepressed adults (P = 0.047) but there were no associations with current episode severity.ConclusionsThree analytic approaches (i.e., DK atlas, DS atlas, and SBM) converge on the notion that cortical thickness is a relatively weak discriminator of current depression status. Differential age and gender effects do not appear to represent key moderators. Robust associations with demographic factors will likely hinder translation of cortical thickness into a clinically useful biomarker. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc. Hum Brain Mapp 38:4370–4385, 2017. © 2017 Wiley Periodicals, Inc.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138250/1/hbm23664_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138250/2/hbm23664.pd

    Optical fiber sensing of strain in synthetic fiber tension members: recent results

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    Strain measurements on synthetic fibre rope constructions ofthe type used in marine applications are reported. The ropes are of a novel construction by virtue of incorporation of fibre-optic sensors for strain measurement. Two instrumentation approaches -a Brillouin strain measuring system and a RF sub-carrier strain measuring system -have been utilised to interrogate the fibre sensors
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