290 research outputs found

    Neural Correlates of Opponent Processes for Financial Gains and Losses

    Get PDF
    Objective: Functional imaging studies offer alternative explanations for the neural correlates of monetary gain and loss related brain activity, and their opponents, omission of gains and losses. One possible explanation based on the psychology of opponent process theory suggests that successful avoidance of an aversive outcome is itself rewarding, and hence activates brain regions involved in reward processing. In order to test this hypothesis, we compared brain activation for successful avoidance of losses and receipt of monetary gains. Additionally, the brain regions involved in processing of frustrative neutral outcomes and actual losses were compared in order to test whether these two representations are coded in common or distinct brain regions. Methods: Using a 3 Tesla functional magnetic resonance imaging machine, fifteen healthy volunteers between the ages 22 to 28 were scanned for blood oxygen level dependent signal changes while they were performing a probabilistic learning task, wherein each trial a participant chose one of the two available options in order to win or avoid losing money. Results: The results confirmed, previous findings showing that medial frontal cortex and ventral striatum show significant activation (p<0.001) not only for monetary gains but also for successful avoidance of losses. A similar activation pattern was also observed for monetary losses and avoidance of gains in the medial frontal cortex, and posterior cingulate cortex, however, there was increased activation in amygdala specific to monetary losses (p<0.001). Further, subtraction analysis showed that regardless of the type of loss (i.e., frustrative neutral outcomes) posterior insula showed increased activation. Conclusion: This study provides evidence for a significant overlap not only between gains and losses, but also between their opponents. The results suggested that the overlapping activity pattern in the medial frontal cortex could be explained by a more abstract function of medial frontal cortex, such as outcome evaluation or performance monitoring, which possibly does not differentiate between winning and losing monetary outcomes.Peer reviewedFinal Published versio

    Adherence in Rheumatoid Arthritis patients assessed with a validated Italian version of the 5-item compliance questionnaire for rheumatology

    Get PDF
    OBJECTIVES: The 5-item Compliance Questionnaire for Rheumatology (CQR5) proved reliability and validity in respect of identification of patients likely to be high adherers (HAs) to anti-rheumatic treatment, or low adherers (LAs), i.e. taking<80% of their medications correctly. The objective of the study was to validate an Italian version of CQR5 (I-CQR5) in rheumatoid arthritis (RA) patients and to investigate factors associated with high adherence. METHODS: RA patients, undergoing treatment with ≥1 self-administered conventional synthetic disease-modifying anti-rheumatic drug (csDMARD) or biological DMARD (bDMARD), were enrolled. The cross-cultural adaptation and validation of I-CQR5 followed standardised guidelines. I-CQR5 was completed by patients on one occasion. Data were subjected to factor analysis and Partial Credit model Parametrisation (PCM) to assess construct validity of I-CQR5. Analysis of factors associated with high adherence included demographic, social, clinical and treatment information. Factors achieving a p<0.10 in univariate analysis were included in multivariable analysis. RESULTS: Among 604 RA patients, 274 patients were included in the validation and 328 in the analysis of factors associated with adherence. Factor analysis and PCM confirmed the construct validity and consistency of I-CQR5. HAs were found to be 109 (35.2%) of the patients. bDMARD treatment and employment were found to be independently associated with high adherence: OR 2.88 (1.36-6.1), p=0.006 and OR 2.36 (1.21-4.62), p=0.012, respectively. CONCLUSIONS: Only one-third of RA patients were HAs according to I-CQR5. bDMARDs and employment status increased by almost 3-fold the likelihood of being highly adherent to the anti-rheumatic treatment.Peer reviewe

    Chandra Observations of the Dwarf Nova WX Hyi in Quiescence

    Full text link
    We report Chandra observations of the dwarf nova WX Hyi in quiescence. The X-ray spectrum displays strong and narrow emission lines of N, O, Mg, Ne, Si, S and Fe. The various ionization states implied by the lines suggest that the emission is produced within a flow spanning a wide temperature range, from T ~ 10^6 K to T >~ 10^8 K. Line diagnostics indicate that most of the radiation originates from a very dense region, with n ~ 10^{13}-10^{14} cm^{-3}. The Chandra data allow the first tests of specific models proposed in the literature for the X-ray emission in quiescent dwarf novae. We have computed the spectra for a set of models ranging from hot boundary layers, to hot settling flows solutions, to X-ray emitting coronae. WX Hyi differs from other dwarf novae observed at minimum in having much stronger low temperature lines, which prove difficult to fit with existing models, and possibly a very strong, broad O VII line, perhaps produced in a wind moving at a few x 10^3 km/s. The accretion rate inferred from the X-rays is lower than the value inferred from the UV. The presence of high-velocity mass ejection could account for this discrepancy while at the same time explaining the presence of the broad O VII line. If this interpretation is correct, it would provide the first detection of a wind from a dwarf nova in quiescence.Comment: accepted to ApJ; 19 pages, 3 figures, 1 tabl

    Reefs at Risk: A Map-Based Indicator of Threats to the Worlds Coral Reefs

    Get PDF
    This report presents the first-ever detailed, map-based assessment of potential threats to coral reef ecosystems around the world. "Reefs at Risk" draws on 14 data sets (including maps of land cover, ports, settle-ments, and shipping lanes), information on 800 sites known to be degraded by people, and scientific expertise to model areas where reef degradation is predicted to occur, given existing human pressures on these areas. Results are an indicator of potential threat (risk), not a measure of actual condition. In some places, particularly where good management is practiced, reefs may be at risk but remain relatively healthy. In others, this indicator underestimates the degree to which reefs are threatened and degraded.Our results indicate that:Fifty-eight percent of the world's reefs are poten-tially threatened by human activity -- ranging from coastal development and destructive fishing practices to overexploitation of resources, marine pollution, and runoff from inland deforestation and farming.Coral reefs of Asia (Southeastern); the most species-rich on earth, are the most threatened of any region. More than 80 percent are at risk (undermedium and high potential threat), and over half are at high risk, primarily from coastal development and fishing-related pressures.Overexploitation and coastal development pose the greatest potential threat of the four risk categories considered in this study. Each, individually, affects a third of all reefs.The Pacific, which houses more reef area than any other region, is also the least threatened. About 60 percent of reefs here are at low risk.Outside of the Pacific, 70 percent of all reefs are at risk.At least 11 percent of the world's coral reefs contain high levels of reef fish biodiversity and are under high threat from human activities. These "hot spot" areas include almost all Philippine reefs, and coral communities off the coasts of Asia, the Comoros, and the Lesser Antilles in the Caribbean.Almost half a billion people -- 8 percent of the total global population -- live within 100 kilometers of a coral reef.Globally, more than 400 marine parks, sanctuaries, and reserves (marine protected areas) contain coral reefs. Most of these sites are very small -- more than 150 are under one square kilometer in size. At least 40 countries lack any marine protected areas for conserving their coral reef systems

    Where is the Radiation Edge in Magnetized Black Hole Accretion discs?

    Full text link
    General Relativistic (GR) Magnetohydrodynamic (MHD) simulations of black hole accretion find significant magnetic stresses near and inside the innermost stable circular orbit (ISCO), suggesting that such flows could radiate in a manner noticeably different from the prediction of the standard model, which assumes that there are no stresses in that region. We provide estimates of how phenomenologically interesting parameters like the ``radiation edge", the innermost ring of the disc from which substantial thermal radiation escapes to infinity, may be altered by stresses near the ISCO. These estimates are based on data from a large number of three-dimensional GRMHD simulations combined with GR ray-tracing. For slowly spinning black holes (a/M<0.9a/M<0.9), the radiation edge lies well inside where the standard model predicts, particularly when the system is viewed at high inclination. For more rapidly spinning black holes, the contrast is smaller. At fixed total luminosity, the characteristic temperature of the accretion flow increases between a factor of 1.22.41.2-2.4 over that predicted by the standard model, whilst at fixed mass accretion rate, there is a corresponding enhancement of the accretion luminosity which may be anywhere from tens of percent to order unity. When all these considerations are combined, we find that, for fixed black hole mass, luminosity, and inclination angle, our uncertainty in the characteristic temperature of the radiation reaching distant observers due to uncertainty in dissipation profile (around a factor of 3) is {\it greater} than the uncertainty due to a complete lack of knowledge of the black hole's spin (around a factor of 2) and furthermore that spin estimates based on the stress-free inner boundary condition provide an upper limit to a/Ma/M.Comment: 20 pages, 17 figures, accepted by MNRAS; major changes to original, including entirely new sections discussing characteristic temperature of black hole accretion flows and implications for measurements of black hole spin, along with substantially expanded conclusio

    Estimation of the parameters of an autoregressive process in the presence of additive white noise

    Get PDF
    technical reportApplications of linear prediction (LP) algorithms have been successful in modeling various physical processes. In the area of speech analysis this has resulted in the development of LP vocoders, devices used in digital speech communication systems. The LP algorithms used in speech and other areas are based on all-pole models for the signal being considered. With white noise excitation to the model, the all-pole LP model is equivalent to the autoregressive (AR) model. With the success of this model for speech well established, the application of LP algorithms in noisy environments is being considered. Existing LP algorithms perform poorly in these conditions. Additive white noise severely effects the intelligibility and quality of speech after analysis by an LP vocoder

    The ASTRO-H X-ray Observatory

    Full text link
    The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
    corecore