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Search Results: 1 - 10 of 18841 matches for " Mark Reynolds "
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A Faster Tableau for CTL*
Mark Reynolds
Computer Science , 2013, DOI: 10.4204/EPTCS.119.7
Abstract: There have been several recent suggestions for tableau systems for deciding satisfiability in the practically important branching time temporal logic known as CTL*. In this paper we present a streamlined and more traditional tableau approach built upon the author's earlier theoretical work. Soundness and completeness results are proved. A prototype implementation demonstrates the significantly improved performance of the new approach on a range of test formulas. We also see that it compares favourably to state of the art, game and automata based decision procedures.
Suzaku Observations of the Galactic Center Microquasar 1E 1740.7-2942
Mark Reynolds,Jon Miller
Physics , 2010, DOI: 10.1088/0004-637X/716/2/1431
Abstract: We present two Suzaku observations of the Galactic center microquasar 1E 1740.7-2942 separated by approximately 700 days. The source was observed on both occasions after a transition to the spectrally hard state. Significant emission from 1E 1740.7-2942 is detected out to an energy of 300 keV, with no spectral break or turnover evident in the data. We tentatively measure a lower limit to the cut-off energy of ~ 380 keV. The spectra are found to be consistent with a Comptonized corona on both occasions, where the high energy emission is consistent with a hard power-law (\Gamma ~ 1.8) with a significant contribution from an accretion disc with a temperature of ~ 0.4 keV at soft X-ray energies. The measured value for the inner radius of the accretion disc is found to be inconsistent with the picture whereby the disc is truncated at large radii in the low-hard state and instead favours a radius close to the ISCO (R_in ~ 10 - 20 R_g).
An Anomalous Quiescent Stellar Mass Black Hole
Mark Reynolds,Jon Miller
Physics , 2011, DOI: 10.1088/2041-8205/734/1/L17
Abstract: We present the results of a 40 ks Chandra observation of the quiescent stellar mass black hole GS 1354-64. A total of 266 net counts are detected at the position of this system. The resulting spectrum is found to be consistent with the spectra of previously observed quiescent black holes, i.e., a power-law with a photon index of \Gamma ~ 2. The inferred luminosity in the 0.5 -- 10 keV band is found to lie in the range 0.5 - 6.5 x 10^{34} erg/s, where the uncertainty in the distance is the dominant source of this large luminosity range. Nonetheless, this luminosity is over an order of magnitude greater than that expected from the known distribution of quiescent stellar mass black hole luminosities and makes GS 1354-64 the only known stellar mass black hole to disagree with this relation. This observation suggests the possibility of significant accretion persisting in the quiescent state.
A Swift survey of accretion onto stellar-mass black holes
Mark Reynolds,Jon Miller
Physics , 2011, DOI: 10.1088/0004-637X/769/1/16
Abstract: We present a systemic analysis of all of the stellar mass black hole binaries (confirmed & candidate) observed by the Swift observatory up to June 2010. The broad Swift bandpass enables a trace of disk evolution over an unprecedented range in flux and temperature. The final data sample consists of 476 X-ray spectra containing greater than 100 counts, in the 0.6 -- 10 keV band. This is the largest sample of high quality CCD spectra of accreting black holes published to date. In addition, strictly simultaneous data at optical/UV wavelengths are available for 255 (54%) of these observations. The data are modelled with a combination of an accretion disk and a hard spectral component. For the hard component we consider both a simple power-law and a thermal Comptonization model. An accretion disk is detected at greater than the 5sigma confidence level in 61% of the observations. Lightcurves and color-color diagrams are constructed for each system. Hardness luminosity and disk fraction luminosity diagrams are constructed and are observed to be consistent with those typically observed by RXTE, noting the sensitivity below 2 keV provided by Swift. The observed spectra have an average luminosity of ~ 1% Eddington, though we are sensitive to accretion disks down to a luminosity of 10^{-3} L_Edd. Thus this is also the largest sample of such cool accretion disks studied to date. (abridged)
The Temporal Logic of two dimensional Minkowski spacetime is decidable
Robin Hirsch,Mark Reynolds
Mathematics , 2015,
Abstract: We consider Minkowski spacetime, the set of all point-events of spacetime under the relation of causal accessibility. That is, ${\sf x}$ can access ${\sf y}$ if an electromagnetic or (slower than light) mechanical signal could be sent from ${\sf x}$ to ${\sf y}$. We use Prior's tense language of ${\bf F}$ and ${\bf P}$ representing causal accessibility and its converse relation. We consider two versions, one where the accessibility relation is reflexive and one where it is irreflexive. In either case it has been an open problem, for decades, whether the logic is decidable or axiomatisable. We make a small step forward by proving, for the case where the accessibility relation is irreflexive, that the set of valid formulas over two-dimensional Minkowski spacetime is decidable, decidability for the reflexive case follows from this. The complexity of either problem is PSPACE-complete. A consequence is that the temporal logic of intervals with real endpoints under either the containment relation or the strict containment relation is PSPACE-complete, the same is true if the interval accessibility relation is "each endpoint is not earlier", or its irreflexive restriction. We provide a temporal formula that distinguishes between three-dimensional and two-dimensional Minkowski spacetime and another temporal formula that distinguishes the two-dimensional case where the underlying field is the real numbers from the case where instead we use the rational numbers.
Global Collaboration in Teacher Education: A Case Study  [PDF]
Greg Neal, Terry Mullins, Anita Reynolds, Mark Angle
Creative Education (CE) , 2013, DOI: 10.4236/ce.2013.49078
Abstract:

Effective online collaboration is a valuable instructional approach appropriate for 21st century teaching and learning. This paper describes a case that involves two higher education student cohorts from the United States and Australia engaged in a global collaboration to promote an authentic teaching and learning experience. The collaboration aims to involve students in sharing, reflecting and synthesizing new knowledge to make a comparative analysis between education systems from the two countries. The global collaboration is matched against an Assessment and Teaching of 21st Century Skills framework to comprehend and justify this approach as part of a teacher education course. This case advocates the value of having future teachers using online resources in a global context as a way to effectively integrate new content with various technology resources to develop new learning and new relationships beyond their own culture.

Bismuth Toxicity: A Rare Cause of Neurologic Dysfunction  [PDF]
Paul T. Reynolds, Kathleen C. Abalos, Jennifer Hopp, Mark E. Williams
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.31010
Abstract: Bismuth subsalicylate (Pepto-Bismol?) and other bismuth-containing compounds have been used for many years to treat gastroenterological complaints. Although safe in the majority of patients, bismuth can cause a well-described toxic state marked by progressive neurological decline. Features of bismuth toxicity include confusion, postural instability, myoclonus, and problems with language. This presentation can masquerade as other causes of progressive neurologic dysfunction including Creutzfeld-Jakob Disease (CJD), Hashimoto’s Encephalopathy, and others. In this case study, we present a patient who was using bismuth salicylate in toxic quantities to help control diarrhea. On initial presentation, several diagnoses were entertained before bismuth levels were obtained. This case study highlights the fact that bismuth toxicity, while rare, should be considered in a patient with progressive neurological decline. Also, we hope this case reminds physicians of a severe consequence of a common, readily available medication.
Free-Flight Odor Tracking in Drosophila Is Consistent with an Optimal Intermittent Scale-Free Search
Andy M. Reynolds, Mark A. Frye
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000354
Abstract: During their trajectories in still air, fruit flies (Drosophila melanogaster) explore their landscape using a series of straight flight paths punctuated by rapid 90° body-saccades [1]. Some saccades are triggered by visual expansion associated with collision avoidance. Yet many saccades are not triggered by visual cues, but rather appear spontaneously. Our analysis reveals that the control of these visually independent saccades and the flight intervals between them constitute an optimal scale-free active searching strategy. Two characteristics of mathematical optimality that are apparent during free-flight in Drosophila are inter-saccade interval lengths distributed according to an inverse square law, which does not vary across landscape scale, and 90° saccade angles, which increase the likelihood that territory will be revisited and thereby reduce the likelihood that near-by targets will be missed. We also show that searching is intermittent, such that active searching phases randomly alternate with relocation phases. Behaviorally, this intermittency is reflected in frequently occurring short, slow speed inter-saccade intervals randomly alternating with rarer, longer, faster inter-saccade intervals. Searching patterns that scale similarly across orders of magnitude of length (i.e., scale-free) have been revealed in animals as diverse as microzooplankton, bumblebees, albatrosses, and spider monkeys, but these do not appear to be optimised with respect to turning angle, whereas Drosophila free-flight search does. Also, intermittent searching patterns, such as those reported here for Drosophila, have been observed in foragers such as planktivorous fish and ground foraging birds. Our results with freely flying Drosophila may constitute the first reported example of searching behaviour that is both scale-free and intermittent.
Light Transmission Patterns in Occluded Tissue: Does Rouleaux Formation Play a Role?
Mark P. McEwen,Karen J. Reynolds
Lecture Notes in Engineering and Computer Science , 2012,
Abstract:
Light Transmission during Occlusion in Species with Differing Rouleaux Formation
Mark P. McEwen,Karen J. Reynolds
Engineering Letters , 2012,
Abstract:
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