704 research outputs found

    Trial frequency effects in human temporal bisection : implications for theories of timing.

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    To contrast the classic version of the Scalar Expectancy Theory (SET) with the Behavioral Economic Model (BEM), we examined the effects of trial frequency on human temporal judgments. Mathematical analysis showed that, in a temporal bisection task, SET predicts that participants should show almost exclusive preference for the response associated with the most frequent duration, whereas BEM predicts that, even though participants will be biased, they will still display temporal control. Participants learned to emit one response (R[S]) after a 1.0-s stimulus and another (R[L]) after a 1.5-s stimulus. Then the effects of varying the frequencies of the 1.0-s and 1.5-s stimuli were assessed. Results were more consistent with BEM than with SET. Overall, this research illustrates how the impact of non-temporal factors on temporal discrimination may help us to contrast associative models such as BEM with cognitive models such as SET. Deciding between these two classes of models has important implications regarding the relations between associative learning and timing. This article is part of a Special Issue entitled: Associative and Temporal Learning.This research was supported by NIH grant MH033881. Jeremie Jozefowiez and Armando Machado acknowledge support from the Fundacao para a Ciencia e a Tecnologia as well as from the European project COST ISCH Action TD0904 "Time in Mental activity" (www.timely-cost.eu). We would like to thank Sean Gannon and Sarah Sterling for help running parts of the experiments, Mario Laborda, Bridget McConnell, Gonzalo Miguez, and James Witnauer for comments on an earlier version of this manuscript. Correspondence concerning this article should be addressed to Jeremie Jozefowiez, laboratoire URECA, Universite Lille Nord de France, Campus de Lille3, Domaine Universitaire du Pont de Bois, BP 60149, 58653 Villeneuve d'Ascq Cedex, France. jeremie.jozefowiez@univ-lille3fr

    The impact of cataract surgery on activities and time-use: results from a longitudinal study in Kenya, Bangladesh and the Philippines.

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    BACKGROUND: Cataract is the leading cause of blindness in the world, and blindness from cataract is particularly common in low-income countries. The aim of this study is to explore the impact of cataract surgery on daily activities and time-use in Kenya, Bangladesh and the Philippines. METHODS/PRINCIPAL FINDINGS: A multi-centre intervention study was conducted in three countries. Time-use data were collected through interview from cases aged >or=50 years with visually impairing cataract (VA or=6/18). Cases were offered free/subsidized cataract surgery. Approximately one year later participants were re-interviewed about time-use. At baseline across the three countries there were 651 cases and 571 controls. Fifty-five percent of cases accepted surgery. Response rate at follow up was 84% (303 out of 361) for operated cases, and 80% (459 out of 571) for controls. At baseline, cases were less likely to carry out and spent less time on productive activities (paid and non-paid work) and spent more time in "inactivity" compared to controls. Approximately one year after cataract surgery, operated cases were more likely to undertake productive activities compared to baseline (Kenya from 55% to 88%; Bangladesh 60% to 95% and Philippines 81% to 94%, p<0.001) and mean time spent on productive activities increased by one-two hours in each setting (p<0.001). Time spent in "inactivity" in Kenya and Bangladesh decreased by approximately two hours (p<0.001). Frequency of reported assistance with activities was more than halved in each setting (p<0.001). CONCLUSIONS/SIGNIFICANCE: The empirical evidence provided by this study of increased time spent on productive activities, reduced time in inactivity and reduced assistance following cataract surgery among older adults in low-income settings has positive implications for well-being and inclusion, and supports arguments of economic benefit at the household level from cataract surgery

    Variation of electric shielding on virtual Frisch-grid detectors

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    Because of the low mobility of holes, CdZnTe (CZT) detectors operate as electron-transport-only type devices whose particular geometrical parameters and contacts configurations are specially chosen to minimize the contribution of uncollected holes into the output signal amplitudes (induction effect). Several detector configurations have been proposed to address this problem. One of them employs a large geometrical aspect ratio, parallelepiped-shaped crystal with two planar contacts on the top and bottom surfaces (anode and cathode) and an additional shielding electrode placed on a crystal\u27s side to create the virtual Frisch-grid effect. We studied the effect of the shielding electrode length, as well as its location, on the responses of 6 x 6 x 15 mm(3) virtual Frisch-grid detectors. We found that the length of the shielding electrode placed next to the anode can be reduced to 5 mm with no adverse effects on the device performance. Meanwhile, this allows for charge loss correction by reading the cathode signal

    Visual Gender Cues Guide Crossmodal Selective Attending to a Gender-Congruent Voice During Dichotic Listening: Supplemental materials

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    These are the supplementary materials for Factor, Polack, & Miller, Visual gender cues guide crossmodal selective attending to a gender-congruent voice during dichotic listening. They include raw data as well as materials and procedures

    Does Cataract Surgery Alleviate Poverty? Evidence from a Multi-Centre Intervention Study Conducted in Kenya, the Philippines and Bangladesh

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    BACKGROUND: Poverty and blindness are believed to be intimately linked, but empirical data supporting this purported relationship are sparse. The objective of this study is to assess whether there is a reduction in poverty after cataract surgery among visually impaired cases. METHODOLOGY/PRINCIPAL FINDINGS: A multi-centre intervention study was conducted in three countries (Kenya, Philippines, Bangladesh). Poverty data (household per capita expenditure--PCE, asset ownership and self-rated wealth) were collected from cases aged ≥50 years who were visually impaired due to cataract (visual acuity<6/24 in the better eye) and age-sex matched controls with normal vision. Cases were offered free/subsidised cataract surgery. Approximately one year later participants were re-interviewed about poverty. 466 cases and 436 controls were examined at both baseline and follow-up (Follow up rate: 78% for cases, 81% for controls), of which 263 cases had undergone cataract surgery ("operated cases"). At baseline, operated cases were poorer compared to controls in terms of PCE (Kenya: 22versus£35p=0.02,Bangladesh:22 versus £35 p = 0.02, Bangladesh: 16 vs 24p=0.004,Philippines:24 p = 0.004, Philippines: 24 vs 32 p = 0.0007), assets and self-rated wealth. By follow-up PCE had increased significantly among operated cases in each of the three settings to the level of controls (Kenya: 30versus£36p=0.49,Bangladesh:30 versus £36 p = 0.49, Bangladesh: 23 vs 23p=0.20,Philippines:23 p = 0.20, Philippines: 45 vs $36 p = 0.68). There were smaller increases in self-rated wealth and no changes in assets. Changes in PCE were apparent in different socio-demographic and ocular groups. The largest PCE increases were apparent among the cases that were poorest at baseline. CONCLUSIONS/SIGNIFICANCE: This study showed that cataract surgery can contribute to poverty alleviation, particularly among the most vulnerable members of society. This study highlights the need for increased provision of cataract surgery to poor people and shows that a focus on blindness may help to alleviate poverty and achieve the Millennium Development Goals

    Causal hierarchy within the thalamo-cortical network in spike and wave discharges

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    Background: Generalised spike wave (GSW) discharges are the electroencephalographic (EEG) hallmark of absence seizures, clinically characterised by a transitory interruption of ongoing activities and impaired consciousness, occurring during states of reduced awareness. Several theories have been proposed to explain the pathophysiology of GSW discharges and the role of thalamus and cortex as generators. In this work we extend the existing theories by hypothesizing a role for the precuneus, a brain region neglected in previous works on GSW generation but already known to be linked to consciousness and awareness. We analysed fMRI data using dynamic causal modelling (DCM) to investigate the effective connectivity between precuneus, thalamus and prefrontal cortex in patients with GSW discharges. Methodology and Principal Findings: We analysed fMRI data from seven patients affected by Idiopathic Generalized Epilepsy (IGE) with frequent GSW discharges and significant GSW-correlated haemodynamic signal changes in the thalamus, the prefrontal cortex and the precuneus. Using DCM we assessed their effective connectivity, i.e. which region drives another region. Three dynamic causal models were constructed: GSW was modelled as autonomous input to the thalamus (model A), ventromedial prefrontal cortex (model B), and precuneus (model C). Bayesian model comparison revealed Model C (GSW as autonomous input to precuneus), to be the best in 5 patients while model A prevailed in two cases. At the group level model C dominated and at the population-level the p value of model C was ∼1. Conclusion: Our results provide strong evidence that activity in the precuneus gates GSW discharges in the thalamo-(fronto) cortical network. This study is the first demonstration of a causal link between haemodynamic changes in the precuneus - an index of awareness - and the occurrence of pathological discharges in epilepsy. © 2009 Vaudano et al

    The LUNEX5 project

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    http://accelconf.web.cern.ch/AccelConf/FEL2012/papers/froa03.pdfInternational audienceLUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, and coherent pulses in the soft X-ray region. The project consists of a Free Electron Laser (FEL) line enabling the most advanced seeding configurations: High order Harmonic in Gas (HHG) seeding and Echo Enable Harmonic Generation (EEHG) with in-vacuum (potentially cryogenic) undulators of 15 and 30 mm period. Two accelerator types feed this FEL line : a 400 MeV Conventional Linear Accelerator (CLA) using superconducting cavities compatible with a future upgrade towards high repetition rate, for the investigations of the advanced FEL schemes; and a 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA), to be qualified in view of FEL application, in the single spike or seeded regime. Two pilot user experiments for timeresolved studies of isolated species and solid state matter dynamics will take benefit of LUNEX5 FEL radiation and provide feedback of the performance of the different schemes under real user conditions

    Performance Factors in Associative Learning: Assessment of the Sometimes Competing Retrieval Model

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    Previous simulations revealed that the sometimes competing retrieval model (SOCR; Stout & Miller, 2007), which assumes local error reduction, can explain many cue interaction phenomena that elude traditional associative theories based on total error reduction. Here we applied SOCR to a new set of Pavlovian phenomena. Simulations used a single set of fixed parameters to simulate each basic effect (e.g., blocking) and, for specific experiments using different procedures, used fitted parameters discovered through hillclimbing. In Simulation 1, SOCR was successfully applied to basic acquisition, including the ‘overtraining effect,’ which is context dependent. In Simulation 2, we applied SOCR to basic extinction and renewal. SOCR anticipated these effects with both fixed parameters and best fitting parameters, although the renewal effects were weaker than those observed in some experiments. In Simulation 3a, feature negative training was simulated, including the often observed transition from second-order conditioning to conditioned inhibition. In Simulation 3b, SOCR predicted the observation that conditioned inhibition after feature-negative and differential conditioning depends on intertrial interval. In Simulation 3c, SOCR successfully predicted failure of conditioned inhibition to extinguish with presentations of the inhibitor alone under most circumstances. In Simulation 4, cue competition, including blocking (4a), recovery from relative validity (4b), and unblocking (4c), were simulated. In Simulation 5, SOCR correctly predicted that inhibitors gain more behavioral control than excitors when they are trained in compound. Simulation 6 demonstrated that SOCR explains the slower acquisition observed following CS-weak shock pairings.SUNY BrockportPsychology Faculty Publication
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