4,805 research outputs found
Earthquake recurrence as a record breaking process
Extending the central concept of recurrence times for a point process to
recurrent events in space-time allows us to characterize seismicity as a record
breaking process using only spatiotemporal relations among events. Linking
record breaking events with edges between nodes in a graph generates a complex
dynamical network isolated from any length, time or magnitude scales set by the
observer. For Southern California, the network of recurrences reveals new
statistical features of seismicity with robust scaling laws. The rupture length
and its scaling with magnitude emerges as a generic measure for distance
between recurrent events. Further, the relative separations for subsequent
records in space (or time) form a hierarchy with unexpected scaling properties
Deep optical observations of the gamma-ray pulsar PSR J0007+7303 in the CTA 1 supernova remnant
The Fermi Large Area Telescope (LAT) discovered the time signature of a
radio-silent pulsar coincident with RX J0007.0+7302, a plerion-like X-ray
source at the centre of the CTA 1 supernova remnant. The inferred timing
parameters of the gamma-ray pulsar PSR J0007+7303 (P=315.8 ms; dot{P}\sim3.6
10^{-13} s s^{-1}) point to a Vela-like neutron star, with an age comparable to
that of CTA 1. The PSR J0007+7303 low distance (\sim 1.4 kpc), interstellar
absorption (A_V\sim 1.6), and relatively high energy loss rate (dot{E} \sim4.5
10^{35} erg s^{-1}), make it a suitable candidate for an optical follow-up.
Here, we present deep optical observations of PSR J0007+7303. The pulsar is not
detected in the Gran Telescopio Canarias (GTC) images down to a limit of r'\sim
27.6 (3 sigma), the deepest ever obtained for this pulsar, while William
Herschel Telescope (WHT) images yield a limit of V \sim 26.9. Our r'-band limit
corresponds to an optical emission efficiency \eta_{opt}= L_{opt}/dot{E} < 9.4
10^{-8}. This limit is more constraining than those derived for other Vela-like
pulsars, but is still above the measured optical efficiency of the Vela pulsar.
We compared the optical upper limits with the extrapolation of the XMM-Newton
X-ray spectrum and found that the optical emission is compatible with the
extrapolation of the X-ray power-law component, at variance with what is
observed, e.g. in the Vela pulsar.Comment: 5 pages, 3 figures, accepted for publication on MNRA
Pilot education and safety awareness programs
Guidelines necessary for the implementation of safety awareness programs for commuter airlines are discussed. A safety office can be viewed as fulfilling either an education and training function or a quality assurance function. Issues such as management structure, motivation, and cost limitations are discussed
Implications of the Optical Observations of Neutron Stars
We show that observations of pulsars with pulsed optical emission indicate
that the peak flux scales according to the magnetic field strength at the light
cylinder. The derived relationships indicate that the emission mechanism is
common across all of the observed pulsars with periods ranging from 33ms to 385
ms and ages of 1000-300,000 years. It is noted that similar trends exist for
ray pulsars. Furthermore the model proposed by Pacini (1971) and
developed by Pacini and Salvati (1983,1987) still has validity and gives an
adequate explanation of the optical phenomena.Comment: 23 pages, 6 figures, accepted for publication in the Astrophysical
Journa
Expression in the human brain of retinoic acid induced 1, a protein associated with neurobehavioural disorders
Acknowledgements Funding was provided by the Wellcome Trust and Tenovus Scotland. Prof Fragoso is the recipient of a Post Doctoral Science without Borders grant from the Brazilian National Council for Scientific and Technological Development (CNPq, 37450/2012- 7). We also thank Aberdeen Proteomics for assistance with the western blots as well as the Microscopy and Histology Core Facility at the University of Aberdeen for confocal microscopy.Peer reviewedPublisher PD
Automatic Reconstruction of Fault Networks from Seismicity Catalogs: 3D Optimal Anisotropic Dynamic Clustering
We propose a new pattern recognition method that is able to reconstruct the
3D structure of the active part of a fault network using the spatial location
of earthquakes. The method is a generalization of the so-called dynamic
clustering method, that originally partitions a set of datapoints into
clusters, using a global minimization criterion over the spatial inertia of
those clusters. The new method improves on it by taking into account the full
spatial inertia tensor of each cluster, in order to partition the dataset into
fault-like, anisotropic clusters. Given a catalog of seismic events, the output
is the optimal set of plane segments that fits the spatial structure of the
data. Each plane segment is fully characterized by its location, size and
orientation. The main tunable parameter is the accuracy of the earthquake
localizations, which fixes the resolution, i.e. the residual variance of the
fit. The resolution determines the number of fault segments needed to describe
the earthquake catalog, the better the resolution, the finer the structure of
the reconstructed fault segments. The algorithm reconstructs successfully the
fault segments of synthetic earthquake catalogs. Applied to the real catalog
constituted of a subset of the aftershocks sequence of the 28th June 1992
Landers earthquake in Southern California, the reconstructed plane segments
fully agree with faults already known on geological maps, or with blind faults
that appear quite obvious on longer-term catalogs. Future improvements of the
method are discussed, as well as its potential use in the multi-scale study of
the inner structure of fault zones
Azithromycin‐Warfarin Interaction: Are We Fishing with a Red Herring?
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90099/1/phco.25.4.630.61028.pd
Observation as a method to enhance collective efficacy: An integrative review
Objectives
This review provides an integrative argument for the use of observation as an intervention to manipulate individual collective efficacy beliefs in sports teams.
Design
An exploration of the conceptual and empirical evidence underpinning observation-based interventions for increasing collective efficacy.
Method
A presentation of reflections on the following. First, we reflect on existing techniques used to increase self- and collective efficacy beliefs. Second, we consider collective efficacy in the context of observational learning and the various modeling techniques employed in the sports and motor performance literature. Third, we highlight relevant literature from neuroscience, outlining the analogous neural pathways evident for social cognition (i.e., collective efficacy) and observation.
Results
This review presents a case for the use of observation interventions to manipulate collective efficacy, drawing upon social psychological frameworks of human behavior, the observation-based literature, and contemporary understanding of brain and behavior.
Conclusions
Observation-based interventions are suited for collective efficacy manipulation in sport. There is a need to advance understanding of this relationship in order to maximize improvements in collective efficacy across group contexts
Variations in solar wind fractionation as seen by ACE/SWICS over a solar cycle and the implications for Genesis Mission results
We use ACE/SWICS elemental composition data to compare the variations in
solar wind fractionation as measured by SWICS during the last solar maximum
(1999-2001), the solar minimum (2006-2009) and the period in which the Genesis
spacecraft was collecting solar wind (late 2001 - early 2004). We differentiate
our analysis in terms of solar wind regimes (i.e. originating from interstream
or coronal hole flows, or coronal mass ejecta). Abundances are normalized to
the low-FIP ion magnesium to uncover correlations that are not apparent when
normalizing to high-FIP ions. We find that relative to magnesium, the other
low-FIP elements are measurably fractionated, but the degree of fractionation
does not vary significantly over the solar cycle. For the high-FIP ions,
variation in fractionation over the solar cycle is significant: greatest for
Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance
ratios are examined as a function of solar wind speed, we find a strong
correlation, with the remarkable observation that the degree of fractionation
follows a mass-dependent trend. We discuss the implications for correcting the
Genesis sample return results to photospheric abundances.Comment: Accepted for publication in Ap
Unpulsed UBV Optical Emission from the Crab Pulsar
Based on observations of the Crab pulsar using the TRIFFID high speed imaging
photometer in the UBV bands using the Special Astrophysical Observatory's 6m
telescope in the Russian Caucasus, we report the detection of pronounced
emission during the so-called `off' phase of emission. Following de-extinction,
this unpulsed component of emission is shown to be consistent with a power law
with an exponent of alpha = -0.60 +/- 0.37, the uncertainty being dominated by
the error associated with the independent CCD photometry used to reference the
TRIFFID data. This suggests a steeper power law form than that reported
elsewhere in the literature for the total integrated spectrum, which is
essentially flat with alpha ~ 0.1, although the difference in this case is only
significant at the ~ 2 sigma level. Deeper reference integrated and TRIFFID
phase-resolved photometry in these bands in conjunction with further
observations in the UV and R region would constrain this fit further.Comment: 26 pages, 2 figures, uses aasms4.sty, accepted for publication in the
Astrophysical Journa
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