868 research outputs found

    Synapsin selectively controls the mobility of resting pool vesicles at hippocampal terminals

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    Presynaptic terminals are specialized sites for information transmission where vesicles fuse with the plasma membrane and are locally recycled. Recent work has extended this classical view, with the observation that a subset of functional vesicles is dynamically shared between adjacent terminals by lateral axonal transport. Conceptually, such transport would be expected to disrupt vesicle retention around the active zone, yet terminals are characterized by a high-density vesicle cluster, suggesting that counteracting stabilizing mechanisms must operate against this tendency. The synapsins are a family of proteins that associate with synaptic vesicles and determine vesicle numbers at the terminal, but their specific function remains controversial. Here, using multiple quantitative fluorescence-based approaches and electron microscopy, we show that synapsin is instrumental for resisting vesicle dispersion and serves as a regulatory element for controlling lateral vesicle sharing between synapses. Deleting synapsin disrupts the organization of presynaptic vesicle clusters, making their boundaries hard to define. Concurrently, the fraction of vesicles amenable to transport is increased, and more vesicles are translocated to the axon. Importantly, in neurons from synapsin knock-out mice the resting and recycling pools are equally mobile. Synapsin, when present, specifically restricts the mobility of resting pool vesicles without affecting the division of vesicles between these pools. Specific expression of synapsin IIa, the sole isoform affecting synaptic depression, rescues the knock-out phenotype. Together, our results show that synapsin is pivotal for maintaining synaptic vesicle cluster integrity and that it contributes to the regulated sharing of vesicles between terminals

    OPTIMISM BIAS IN MANAGING IT PROJECT RISKS: A CONSTRUAL LEVEL THEORY PERSPECTIVE

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    Prior research has shown that people have a tendency to be overly optimistic about future events (i.e., optimism bias) in a variety of settings. In this study, we suggest that optimism bias has significant implications for IT project risk management, as it may cause people to become overly optimistic that they can easily manage project risks. Drawing upon construal level theory (CLT), we investigate optimism bias in managing IT project risks. Based on an experiment with IT professionals, we found that a high-level construal of a project risk leads individuals to have a more optimistic perception about successfully managing the project risk, causes them to focus more on benefits over costs in choosing a risk management plan, and leads them to identify more pros than cons associated with a risk management plan relative to a low-level construal. Implications for both theory and practice are discussed

    Separating Quantum Communication and Approximate Rank

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    One of the best lower bound methods for the quantum communication complexity of a function H (with or without shared entanglement) is the logarithm of the approximate rank of the communication matrix of H. This measure is essentially equivalent to the approximate gamma-2 norm and generalized discrepancy, and subsumes several other lower bounds. All known lower bounds on quantum communication complexity in the general unbounded-round model can be shown via the logarithm of approximate rank, and it was an open problem to give any separation at all between quantum communication complexity and the logarithm of the approximate rank. In this work we provide the first such separation: We exhibit a total function H with quantum communication complexity almost quadratically larger than the logarithm of its approximate rank. We construct H using the communication lookup function framework of Anshu et al. (FOCS 2016) based on the cheat sheet framework of Aaronson et al. (STOC 2016). From a starting function F, this framework defines a new function H=F_G. Our main technical result is a lower bound on the quantum communication complexity of F_G in terms of the discrepancy of F, which we do via quantum information theoretic arguments. We show the upper bound on the approximate rank of F_G by relating it to the Boolean circuit size of the starting function F

    Recent updates on incubation of drug craving: a mini-review

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    Cue-induced drug craving progressively increases after prolonged withdrawal from drug self-administration in laboratory animals, a behavioral phenomenon termed 'incubation of drug craving.' Studies over the years have revealed several important neural mechanisms contributing to incubation of drug craving. In this mini-review, we first discuss three excellent Addiction Biology publications on incubation of drug craving in both human and laboratory animals. We then review several key publications from the past year on behavioral and mechanistic findings related to incubation of drug craving

    Selected Adnexal Cystic Masses in Postmenopausal Women Can be Safely Managed by Laparoscopy

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    The aim of this study was to assess the efficacy and safety of laparoscopic treatment for adnexal cystic masses that were predicted to be benign in postmenopausal women. Postmenopausal women found to have an adnexal cystic mass were retrospectively evaluated with transvaginal ultrasonography, and serum CA-125 levels. The selection criteria were adnexal cystic masses greater than 3 cm but less than 10 cm, the masses were in the benign range (4-8) of Sassone's scoring system for transvaginal ultrasonography, and the patients had serum CA-125 levels less than 65 IU/mL. Two hundred nineteen women fulfilled the criteria and underwent operative laparoscopy. Almost all the masses (99.5%) were accurately predicted to be benign except for one borderline ovarian tumor. Two hundreds thirteen (97.3%) women were successfully managed by operative laparoscopy and six (2.7%) required laparotomy. For the patients managed by laparoscopy, the mean operative time was 51.3 min; the mean hospital stay was 2.5 days. There was no significant morbidity and surgery-related mortality. The combination of the Sassone's scoring system for transvaginal ultrasonography and serum CA-125 level can accurately predict benign cystic masses, and operative laparoscopy is technically feasible and safe for the management of adnexal mass in postmenopausal women

    Effect of Fabric Deformation on Thermal Protective Performance of Clothing in a Cylindrical Configuration

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    Firefighting protective clothing is designed to provide thermal protection for firefighters in fire extinguishing or rescuing operations. However, fabric deformation and stretching due to body movement and different postures could change the clothing\u27s thermal protective performance. Current gaps in our knowledge with regard to fabric deformation often resulted in biased predictions of the thermal protective level that personal protective equipment (PPE) can provide, highlighting the need to improve our understanding in this field. In this study, we developed a device that can be connected to a cylindrical copper calorimeter to simulate fabric deformation due to body movement and different postures and simultaneously measure the fabric\u27s thermal properties. Stretching forces of varying magnitudes (of 0, 1.2, 2.1, and 3.1 psi) were applied to study the effect of fabric deformation on the thermal protective performance of clothing under low- and high-intensity heat exposures. In addition, we analyzed skin burn times with different stretching forces and fabric properties. The selected fabrics were stretched by approximately 15 % under a stretching force of 3.1 psi. Fabric deformation led to a significant reduction of the predicted thermal protective performance of fabrics, mainly due to changes in fabric thickness, porosity, and mass per unit area. Predicted skin burn times decreased for increasing stretching forces, although the decrease was less pronounced under high-intensity heat exposure as a result of fabric shrinkage and degradation. The findings from this study further advance our current understanding of the thermal protective performance of clothing and may lead to the development of a new test to characterize clothing performance under more realistic usage situations

    Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress

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    In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse
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