Phased Array Ultrasonic Inspection Method for Homogeneous Tube Inspection Over Wide Oblique Angle Range

As seamless tube manufacturers push quality requirements for their products, automated phased array Rotating Tube Inspection Systems (RTIS) are now required to provide continuous NDE detection performances over a wide angular range of oblique flaws. One major impact of this new reality is a paradigm shift for the calibration method driven by the requirement to meet homogeneous detection over broad oblique flaw angle intervals, whereas standard practice only requires calibration at specific discrete angles. An innovative method specifically designed to obtain high productivity and homogeneous inspection measurements over an oblique flaw range extending from -45 to 45 degrees is presented. Experimental results from the application of the method on various tubes presenting multiple artificial flaws support the quantitative performance evaluation

Increased precision in the intravascular arterial input function with flow compensation

Abstract: Purpose: In this study, we investigate the effects of pulsatile flow and inflow on dynamic susceptibility-contrast MRI (DSC-MRI) intravascular arterial input function (AIF) measurement in human brain arteries and measure how they are affected by first-order flow compensation (FC). Methods: A dual-echo single-shot EPI sequence with alternating FC gradients was used to acquire DSC-MRI data with electrocardiogram monitoring. The dynamic signal variations measured inside the middle- (MCA) and internal cerebral arteries (ICA) was associated to the pulsatile arterial blood velocities measured with a single-slice quantitative flow sequence throughout the cardiac cycle. Results: Major inverse correlations between intravascular signal and blood velocity were found for the standard SS-EPI sequence. FC reduces these correlated variations that contribute to signal physiological noise. It causes a significant two-fold increase of intravascular SNR in the MCA and the ICA, (2.3 ± 0.9, P = 0.03) and (2.0 ± 0.9, P = 0.04) respectively; and reduced phase standard deviation for the ICA (0.72 ± 0.14, P = 0.004). The correction proposed in this work translates into a quantitative AIF with reduced noise in the ICA. Conclusion: The physiological noise added by pulsatile flow and inflow for intravascular AIF measurement in the brain arteries is significantly reduced by FC

Risk perception and risk-taking among skateboarders

International audienceSkateboarding is considered to be a high risk activity. Although many studies have identified risk factors associated with skateboarding injuries, few have provided detailed in-depth knowledge on participants' psychological dispositions towards risk behaviors. The aim of this study was to identify individual factors associated with risk perception and risk-taking among skateboarders. Telephone interviews were conducted with 158 skateboarders (mean age = 18.1 years) recruited in 11 Montreal skateparks. Age, self-efficacy, previous injuries, fear of being injured, sensation seeking and experience level were all included in two linear regression models that were run for risk perception and risk-taking. Age, experience level, sensation seeking, and risk perception are significant explanatory variables of risk-taking. Results show that sensation seeking was the only significant factor associated with risk perception. These results allow for a better understanding of the behavior of skateboarders, they highlight the importance of impulsive sensation seeking in risk perception as well as risk-taking. This study characterizes skateboarders who take risks and provides additional information on interventions for injury prevention

The effect of efferentiectomy and orchidectomy on the metabolism of the epididymis of the mouse

The purpose of the study is a comparison of respiratory metabolic rates and anaerobic glycolytic activity (lactate accumulation) in homogenates of epididymides from normal, orchidectomized and testosterone replaced-orchidectomized mice. Animals subjected to vasa efferentiectomy were used to furnish sperm free homogenates as controls for the homogenates from orchidectomized animals, and to furnish estimates of the contribution of the spermatozoa to these metabolic parameters in homogenates of normal epididymides. Efferentiectomized mice yield homogenates with a significantly lowered rate of respiratory activity (30%). Experiments with fractions of these homogenates showed this reduction in activity to be equivalent to the contribution of the spermatozoa in homogenates from normal mice. No significant difference in the rate of respiratory metabolism was observed among homogenates obtained from efferentiectomized, orchidectomized, testosterone replaced-orchidectomized, or testosterone injected-efferentiectomized mice. Efferentiectomy also resulted in a lowered rate of anaerobic glycolytic activity in vitro . No further reduction or elevation of this activity was observed in homogenates from orchidectomized or testosterone injected animals. Further study indicated this loss following efferentiectomy to be due to a reduced glycolytic activity in the epididymal epithelium rather than to the absence of spermatozoan contribution to the metabolism. The evidence presented supports the hypothesis that the presence of some component of the spermatozoa or the fluids in which they reside controls the activation or inhibition of a segment of the lactic dehydrogenase activity which is responsible for the secretion of lactic acid into the epididymal canal for spermatozoan utilization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50126/1/1030660306_ftp.pd

Brevenal Inhibits Pacific Ciguatoxin-1B-Induced Neurosecretion from Bovine Chromaffin Cells

Ciguatoxins and brevetoxins are neurotoxic cyclic polyether compounds produced by dinoflagellates, which are responsible for ciguatera and neurotoxic shellfish poisoning (NSP) respectively. Recently, brevenal, a natural compound was found to specifically inhibit brevetoxin action and to have a beneficial effect in NSP. Considering that brevetoxin and ciguatoxin specifically activate voltage-sensitive Na+ channels through the same binding site, brevenal has therefore a good potential for the treatment of ciguatera. Pacific ciguatoxin-1B (P-CTX-1B) activates voltage-sensitive Na+ channels and promotes an increase in neurotransmitter release believed to underpin the symptoms associated with ciguatera. However, the mechanism through which slow Na+ influx promotes neurosecretion is not fully understood. In the present study, we used chromaffin cells as a model to reconstitute the sequence of events culminating in ciguatoxin-evoked neurosecretion. We show that P-CTX-1B induces a tetrodotoxin-sensitive rise in intracellular Na+, closely followed by an increase in cytosolic Ca2+ responsible for promoting SNARE-dependent catecholamine secretion. Our results reveal that brevenal and β-naphtoyl-brevetoxin prevent P-CTX-1B secretagogue activity without affecting nicotine or barium-induced catecholamine secretion. Brevenal is therefore a potent inhibitor of ciguatoxin-induced neurotoxic effect and a potential treatment for ciguatera

Interaction of language, auditory and memory brain networks in auditory verbal hallucinations

Auditory verbal hallucinations (AVH) occur in psychotic disorders, but also as a symptom of other conditions and even in healthy people. Several current theories on the origin of AVH converge, with neuroimaging studies suggesting that the language, auditory and memory/limbic networks are of particular relevance. However, reconciliation of these theories with experimental evidence is missing. We review 50 studies investigating functional (EEG and fMRI) and anatomic (diffusion tensor imaging) connectivity in these networks, and explore the evidence supporting abnormal connectivity in these networks associated with AVH. We distinguish between functional connectivity during an actual hallucination experience (symptom capture) and functional connectivity during either the resting state or a task comparing individuals who hallucinate with those who do not (symptom association studies). Symptom capture studies clearly reveal a pattern of increased coupling among the auditory, language and striatal regions. Anatomical and symptom association functional studies suggest that the interhemispheric connectivity between posterior auditory regions may depend on the phase of illness, with increases in non-psychotic individuals and first episode patients and decreases in chronic patients. Leading hypotheses involving concepts as unstable memories, source monitoring, top-down attention, and hybrid models of hallucinations are supported in part by the published connectivity data, although several caveats and inconsistencies remain. Specifically, possible changes in fronto-temporal connectivity are still under debate. Precise hypotheses concerning the directionality of connections deduced from current theoretical approaches should be tested using experimental approaches that allow for discrimination of competing hypotheses

SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues

Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types