235 research outputs found

    Revealing Dissociable Attention Biases in Chronic Smokers Through an Individual-Differences Approach

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    Addiction is accompanied by attentional biases (AB), wherein drug-related cues grab attention independently of their perceptual salience. AB have emerged in different flavours depending on the experimental approach, and their clinical relevance is still debated. In chronic smokers we sought evidence for dissociable attention abnormalities that may play distinct roles in the clinical manifestations of the disorder. Fifty smokers performed a modified visual probe-task measuring two forms of AB and their temporal dynamics, and data on their personality traits and smoking history/ status were collected. Two fully dissociable AB effects were found: A Global effect, reflecting the overall impact of smoke cues on attention, and a Location-specific effect, indexing the impact of smoke cues on visuospatial orienting. Importantly, the two effects could be neatly separated from one another as they: (i) unfolded with dissimilar temporal dynamics, (ii) were accounted for by different sets of predictors associated with personality traits and smoking history and (iii) were not correlated with one another. Importantly, the relevance of each of these two components in the single individual depends on a complex blend of personality traits and smoking habits, a result that future efforts addressing the clinical relevance of addiction-related AB should take into careful consideration.This study was supported by funding provided by the University of Verona to CDL, CC and L

    Observing Neutral Hydrogen Above Redshift 6: The "Global" Perspective

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    Above redshift 6, the dominant source of neutral hydrogen in the Universe shifts from localized clumps in and around galaxies and filaments to a pervasive, diffuse component of the intergalactic medium (IGM). This transition tracks the global neutral fraction of hydrogen in the IGM and can be studied, in principle, through the redshifted 21 cm hyperfine transition line. During the last half of the reionization epoch, the mean (global) brightness temperature of the redshifted 21 cm emission is proportional to the neutral fraction, but at earlier times (10 < z < 25), the mean brightness temperature should probe the spin temperature of neutral hydrogen in the IGM. Measuring the (of order 10 mK) mean brightness temperature of the redshifted 21 cm line as a function of frequency (and hence redshift) would chart the early evolution of galaxies through the heating and ionizing of the IGM by their stellar populations. Experiments are already underway to accomplish this task or, at least, provide basic constraints on the evolution of the mean brightness temperature. We provide a brief overview of one of these projects, the Experiment to the Detect the Global EOR Signature (EDGES), and discuss prospects for future results.Comment: From AIP Conference Proceedings, Volume 1035, 2008, "The Evolution of Galaxies through the Neutral Hydrogen Window". 3 page

    The Utilization of Data Analysis Techniques in Predicting Student Performance in Massive Open Online Courses (MOOCs)

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    The growth of the Internet has enabled the popularity of open online learning platforms to increase over the years. This has led to the inception of Massive Open Online Courses (MOOCs) that enrol, millions of people, from all over the world. Such courses operate under the concept of open learning, where content does not have to be delivered via standard mechanisms that institutions employ, such as physically attending lectures. Instead learning occurs online via recorded lecture material and online tasks. This shift has allowed more people to gain access to education, regardless of their learning background. However, despite these advancements in delivering education, completion rates for MOOCs are low. In order to investigate this issue, the paper explores the impact that technology has on open learning and identifies how data about student performance can be captured to predict trend so that at risk students can be identified before they drop-out. In achieving this, subjects surrounding student engagement and performance in MOOCs and data analysis techniques are explored to investigate how technology can be used to address this issue. The paper is then concluded with our approach of predicting behaviour and a case study of the eRegister system, which has been developed to capture and analyse data. Keywords: Open Learning; Prediction; Data Mining; Educational Systems; Massive Open Online Course; Data Analysi

    Prophylactic ciprofloxacin treatment prevented high mortality, and modified systemic and intestinal immune function in tumour-bearing rats receiving dose-intensive CPT-11 chemotherapy

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    Infectious complications are a major cause of morbidity and mortality from dose-intensive cancer chemotherapy. In spite of the importance of intestinal bacteria translocation in these infections, information about the effect of high-dose chemotherapy on gut mucosal immunity is minimal. We studied prophylactic ciprofloxacin (Cipro) treatment on irinotecan (CPT-11) toxicity and host immunity in rats bearing Ward colon tumour. Cipro abolished chemotherapy-related mortality, which was 45% in animals that were not treated with Cipro. Although Cipro reduced body weight loss and muscle wasting, it was unable to prevent severe late-onset diarrhoea. Seven days after CPT-11, splenocytes were unable to proliferate (stimulation index=0.10±0.02) and produce proliferative and inflammatory cytokines (i.e., Interleukin (IL)-2, interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α) IL-1β, IL-6) on mitogen stimulation in vitro (P<0.05 vs controls), whereas mesenteric lymph node (MLN) cells showed a hyper-proliferative response and a hyper-production of pro-inflammatory cytokines on mitogen stimulation. This suggests compartmentalised effects by CPT-11 chemotherapy on systemic and intestinal immunity. Cipro normalised the hyper-responsiveness of MLN cells, and in the spleen, it partially restored the proliferative response and normalised depressed production of IL-1β and IL-6. Taken together, Cipro prevented infectious challenges associated with immune hypo-responsiveness in systemic immune compartments, and it may also alleviate excessive pro-inflammatory responses mediating local gut injury

    The use of insulin declines as patients live farther from their source of care: results of a survey of adults with type 2 diabetes

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    BACKGROUND: Although most diabetic patients do not achieve good physiologic control, patients who live closer to their source of primary care tend to have better glycemic control than those who live farther away. We sought to assess the role of travel burden as a barrier to the use of insulin in adults with diabetes METHODS: 781 adults receiving primary care for type 2 diabetes were recruited from the Vermont Diabetes Information System. They completed postal surveys and were interviewed at home. Travel burden was estimated as the shortest possible driving distance from the patient's home to the site of primary care. Medication use, age, sex, race, marital status, education, health insurance, duration of diabetes, and frequency of care were self-reported. Body mass index was measured by a trained field interviewer. Glycemic control was measured by the glycosolated hemoglobin A1C assay. RESULTS: Driving distance was significantly associated with insulin use, controlling for the covariates and potential confounders. The odds ratio for using insulin associated with each kilometer of driving distance was 0.97 (95% confidence interval 0.95, 0.99; P = 0.01). The odds ratio for using insulin for those living within 10 km (compared to those with greater driving distances) was 2.29 (1.35, 3.88; P = 0.02). DISCUSSION: Adults with type 2 diabetes who live farther from their source of primary care are significantly less likely to use insulin. This association is not due to confounding by age, sex, race, education, income, health insurance, body mass index, duration of diabetes, use of oral agents, glycemic control, or frequency of care, and may be responsible for the poorer physiologic control noted among patients with greater travel burdens

    First High-Convergence Cryogenic Implosion in a Near-Vacuum Hohlraum

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    Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ~ 3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8×10[superscript 15] neutrons, with 20% calculated alpha heating at convergence ~27×

    Thin Shell, High Velocity Inertial Confinement Fusion Implosions on the National Ignition Facility

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    Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165  μm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1/2 the neutron yield coming from α-particle self-heating
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