260 research outputs found
A habituation account of change detection in same/different judgments
We investigated the basis of change detection in a short-term priming task. In two experiments, participants were asked to indicate whether or not a target word was the same as a previously presented cue. Data from an experiment measuring magnetoencephalography failed to find different patterns for âsameâ and âdifferentâ responses, consistent with the claim that both arise from a common neural source, with response magnitude defining the difference between immediate novelty versus familiarity. In a behavioral experiment, we tested and confirmed the predictions of a habituation account of these judgments by comparing conditions in which the target, the cue, or neither was primed by its presentation in the previous trial. As predicted, cue-primed trials had faster response times, and target-primed trials had slower response times relative to the neither-primed baseline. These results were obtained irrespective of response repetition and stimulusâresponse contingencies. The behavioral and brain activity data support the view that detection of change drives performance in these tasks and that the underlying mechanism is neuronal habituation
The Extended X-ray Halo of the Crab-like SNR G21.5-0.9
Recent XMM-Newton observations reveal an extended (150") low-surface
brightness X-ray halo in the supernova remnant G21.5-0.9. The near circular
symmetry, the lack of any limb brightening and the non-thermal spectral form,
all favour an interpretation of this outer halo as an extension of the central
synchrotron nebula rather than as a shell formed by the supernova blast wave
and ejecta. The X-ray spectrum of the nebula exhibits a marked spectral
softening with radius, with the power-law spectral index varying from Gamma =
1.63 +/- 0.04 in the core to Gamma = 2.45 +/- 0.06 at the edge of the halo.
Similar spectral trends are seen in other Crab-like remnants and reflect the
impact of the synchrotron radiation losses on very high energy electrons as
they diffuse out from the inner nebula. A preliminary timing analysis provides
no evidence for any pulsed X-ray emission from the core of G21.5-0.9.Comment: 6 pages. Accepted for publication in the Astronomy and Astrophysics
Special Issue on 1st science with XMM-Newto
Entanglements of faith: Discourses, practices of care and homeless people in an Italian City of Saints
This is the author accepted manuscript. The final version is available from SAGE via http://dx.doi.org/10.1177/0042098013514620This paper investigates how Catholic-inspired services for homeless people are delivered in Turin, Italy. The purpose is to critically interrogate particular faith-based organisationsâ moral discourses on homelessness, and to show how they are enacted through practices of care directed at the homeless subject. The paper contributes to the geographical literature on faith-based organisations addressing its shortcomings â namely the lack of critical and contextual focus on faith-based organisationsâ âlove for the poorâ. To address this point, the paper takes a vitalist perspective on the urban and introduces the notion of the âentanglements of faithâ, which allows an integrated and grounded perspective on faith-based organisationsâ interventions. The outcomes of the work suggest that these faith-based organisations propose standardised services that, producing particular assemblages and affective atmospheres, have deep emotional and relational effects on their recipients. Further lines of research are sketched in the conclusions
The Relation Between the Surface Brightness and the Diameter for Galactic Supernova Remnants
In this work, we have constructed a relation between the surface brightness
() and diameter (D) of Galactic C- and S-type supernova remnants
(SNRs). In order to calibrate the -D dependence, we have carefully
examined some intrinsic (e.g. explosion energy) and extrinsic (e.g. density of
the ambient medium) properties of the remnants and, taking into account also
the distance values given in the literature, we have adopted distances for some
of the SNRs which have relatively more reliable distance values. These
calibrator SNRs are all C- and S-type SNRs, i.e. F-type SNRs (and S-type SNR
Cas A which has an exceptionally high surface brightness) are excluded. The
Sigma-D relation has 2 slopes with a turning point at D=36.5 pc: (at 1
GHz)=8.4 D
WmHzster (for
WmHzster and D36.5 pc) and (at 1
GHz)=2.7 10 D
WmHzster (for
WmHzster and D36.5 pc). We discussed the theoretical
basis for the -D dependence and particularly the reasons for the change
in slope of the relation were stated. Added to this, we have shown the
dependence between the radio luminosity and the diameter which seems to have a
slope close to zero up to about D=36.5 pc. We have also adopted distance and
diameter values for all of the observed Galactic SNRs by examining all the
available distance values presented in the literature together with the
distances found from our -D relation.Comment: 45 pages, 2 figures, accepted for publication in Astronomical and
Astrophysical Transaction
The Local Bubble, Local Fluff, and Heliosphere
The properties of the Local Bubble, Local Fluff complex of nearby
interstellar clouds, and the heliosphere are mutually constrained by data and
theory. Observations and models of the diffuse radiation field, interstellar
ionization, pick-up ion and anomalous cosmic-ray populations, and interstellar
dust link the physics of these regions. The differences between the
one-asymmetric-superbubble and two-superbubble views of the Local Bubble are
discussed.Comment: 10 pages, 2 figure
Knowledge and innovation: The strings between global and local dimensions of sustainable growth
The modern growth literature pays much attention to innovation and knowledge as drivers of endogenous developments in a competitive open economic system. This paper reviews concisely the literature in this field and addresses in particular micro- and macro-economic interactions at local or regional levels, based on clustering and networking principles, in which sustainability conditions also play a core role. The paper then develops a so-called knowledge circuit model comprising the relevant stakeholders, which aims to offer a novel framework for applied policy research at the meso-economic level
Diffusive Synchrotron Radiation from Pulsar Wind Nebulae
Diffusive Synchrotron Radiation (DSR) is produced by charged particles as
they random walk in a stochastic magnetic field. The spectrum of the radiation
produced by particles in such fields differs substantially from those of
standard synchrotron emission because the corresponding particle trajectories
deviate significantly from gyration in a regular field. The Larmor radius,
therefore, is no longer a good measure of the particle trajectory. In this
paper we analyze a special DSR regime which arises as highly relativistic
electrons move through magnetic fields which have only random structure on a
wide range of spatial scales. Such stochastic fields arise in turbulent
processes, and are likely present in pulsar wind nebulae (PWNe). We show that
DSR generated by a single population of electrons can reproduce the observed
broad-band spectra of PWNe from the radio to the X-ray, in particular producing
relatively flat spectrum radio emission as is usually observed in PWNe. DSR can
explain the existence of several break frequencies in the broad-band emission
spectrum without recourse to breaks in the energy spectrum of the relativistic
particles. The shape of the radiation spectrum depends on the spatial spectrum
of the stochastic magnetic field. The implications of the presented DSR regime
for PWN physics are discussed.Comment: 15 pages, 5 figures, accepted to MNRA
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