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Search Results: 1 - 10 of 244091 matches for " Robert C. Bishop "
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Brussels-Austin Nonequilibrium Statistical Mechanics in the Early Years: Similarity Transformations between Deterministic and Probabilistic Descriptions
Robert C. Bishop
Physics , 2003,
Abstract: The fundamental problem on which Ilya Prigogine and the Brussels-Austin Group have focused can be stated briefly as follows. Our observations indicate that there is an arrow of time in our experience of the world (e.g., decay of unstable radioactive atoms like Uranium, or the mixing of cream in coffee). Most of the fundamental equations of physics are time reversible, however, presenting an apparent conflict between our theoretical descriptions and experimental observations. Many have thought that the observed arrow of time was either an artifact of our observations or due to very special initial conditions. An alternative approach, followed by the Brussels-Austin Group, is to consider the observed direction of time to be a basics physical phenomenon and to develop a mathematical formalism that can describe this direction as being due to the dynamics of physical systems. In part I of this essay, I review and assess an attempt to carry out an approach that received much of their attention from the early 1970s to the mid 1980s. In part II, I will discuss their more recent approach using rigged Hilbert spaces.
Brussels-Austin Nonequilibrium Statistical Mechanics in the Later Years: Large Poincare Systems and Rigged Hilbert Space
Robert C. Bishop
Physics , 2003,
Abstract: This second part of a two-part essay discusses recent developments in the Brussels-Austin Group after the mid 1980s. The fundamental concerns are the same as in their similarity transformation approach (see Part I), but the contemporary approach utilizes rigged Hilbert space (whereas the older approach used Hilbert space). While the emphasis on nonequilibrium statistical mechanics remains the same, the use of similarity transformations shifts to the background. In its place arose an interest in the physical features of large Poincar\U{e9} systems, nonlinear dynamics and the mathematical tools necessary to analyze them.
Resonances, Unstable Systems and Irreversibility: Matter Meets Mind
Robert C. Bishop
Physics , 2005, DOI: 10.1007/s10773-005-8954-6
Abstract: The fundamental time-reversal invariance of dynamical systems can be broken in various ways. One way is based on the presence of resonances and their interactions giving rise to unstable dynamical systems, leading to well-defined time arrows. Associated with these time arrows are semigroups bearing time orientations. Usually, when time symmetry is broken, two time-oriented semigroups result, one directed toward the future and one directed toward the past. If time-reversed states and evolutions are excluded due to resonances, then the status of these states and their associated backwards-in-time oriented semigroups is open to question. One possible role for these latter states and semigroups is as an abstract representation of mental systems as opposed to material systems. The beginnings of this interpretation will be sketched.
Determinism and Indeterminism
Robert C. Bishop
Physics , 2005,
Abstract: Determinism and indeterminism in physical theories are reviewed and some broader implications of determinism are discussed.
The Arrow of Time in Rigged Hilbert Space Quantum Mechanics
Robert C. Bishop
Physics , 2005,
Abstract: Arno Bohm and Ilya Prigogine's Brussels-Austin Group have been working on the quantum mechanical arrow of time and irreversibility in rigged Hilbert space quantum mechanics. A crucial notion in Bohm's approach is the so-called preparation/registration arrow. An analysis of this arrow and its role in Bohm's theory of scattering is given. Similarly, the Brussels-Austin Group uses an excitation/de-excitation arrow for ordering events, which is also analyzed. The relationship between the two approaches is initially discussed focusing on their semi-group operators and time arrows. Finally a possible realist interpretation of the rigged Hilbert space formulation of quantum mechanics is considered.
Quantum Time Arrows, Semigroups and Time-Reversal in Scattering
Robert C. Bishop
Physics , 2002,
Abstract: Two approaches toward the arrow of time for scattering processes have been proposed in rigged Hilbert space quantum mechanics. One, due to Arno Bohm, involves preparations and registrations in laboratory operations and results in two semigroups oriented in the forward direction of time. The other, employed by the Brussels-Austin group, is more general, involving excitations and de-excitations of systems, and apparently results in two semigroups oriented in opposite directions of time. It turns out that these two time arrows can be related to each other via Wigner's extensions of the spacetime symmetry group. Furthermore, their are subtle differences in causality as well as the possibilities for the existence and creation of time-reversed states depending on which time arrow is chosen.
The Hangulphabet: A Descriptive Alphabet
Robert Bishop,Ruggero Micheletto
Computer Science , 2012,
Abstract: This paper describes the Hangulphabet, a new writing system that should prove useful in a number of contexts. Using the Hangulphabet, a user can instantly see voicing, manner and place of articulation of any phoneme found in human language. The Hangulphabet places consonant graphemes on a grid with the x-axis representing the place of articulation and the y-axis representing manner of articulation. Each individual grapheme contains radicals from both axes where the points intersect. The top radical represents manner of articulation where the bottom represents place of articulation. A horizontal line running through the middle of the bottom radical represents voicing. For vowels, place of articulation is located on a grid that represents the position of the tongue in the mouth. This grid is similar to that of the IPA vowel chart (International Phonetic Association, 1999). The difference with the Hangulphabet being the trapezoid representing the vocal apparatus is on a slight tilt. Place of articulation for a vowel is represented by a breakout figure from the grid. This system can be used as an alternative to the International Phonetic Alphabet (IPA) or as a complement to it. Beginning students of linguistics may find it particularly useful. A Hangulphabet font has been created to facilitate switching between the Hangulphabet and the IPA.
Competency Tracking for English as a Second or Foreign Language Learners
Robert Bishop Jr
Computer Science , 2013,
Abstract: My system utilizes the outcomes feature found in Moodle and other learning content management systems (LCMSs) to keep track of where students are in terms of what language competencies they have mastered and the competencies they need to get where they want to go. These competencies are based on the Common European Framework for (English) Language Learning. This data can be available for everyone involved with a given student's progress (e.g. educators, parents, supervisors and the students themselves). A given student's record of past accomplishments can also be meshed with those of his classmates. Not only are a student's competencies easily seen and tracked, educators can view competencies of a group of students that were achieved prior to enrollment in the class. This should make curriculum decision making easier and more efficient for educators.
Hypofractionated Prostate Radiotherapy with or without Conventionally Fractionated Nodal Irradiation: Clinical Toxicity Observations and Retrospective Daily Dosimetry
Andrew M. McDonald,Justin M. Bishop,Rojymon Jacob,Michael C. Dobelbower,Robert Y. Kim,Eddy S. Yang,Heather Smith,Xingen Wu,John B. Fiveash
Prostate Cancer , 2012, DOI: 10.1155/2012/546794
Abstract: Purpose. To evaluate toxicity associated with the addition of elective nodal irradiation (ENI) to a hypofractionated regimen for the treatment of prostate cancer. Methods and Materials. Fifty-seven patients received pelvic image-guided IMRT to 50.4?Gy in 28 fractions with a hypofractionated simultaneous boost to the prostate to 70?Gy. Thirty-one patients received prostate-only treatment to 70?Gy in 28 fractions. Results. Median followup was 41.1 months. Early grade ≥2 urinary toxicity rates were 49% (28 of 57) for patients receiving ENI and 58% (18 of 31) for those not ( ). Early grade ≥2 rectal toxicity rates were 40% (23 of 57) and 23% (7 of 31), respectively ( ). The addition of ENI resulted in a 21% actuarial rate of late grade ≥2 rectal toxicity at 4 years, compared to 0% for patients treated to the prostate only ( ). Retrospective daily dosimetry of patients experiencing late rectal toxicity revealed an average increase of 2.67% of the rectal volume receiving 70?Gy compared to the original plan. Conclusions. The addition of ENI resulted in an increased risk of late rectal toxicity. Grade ≥2 late rectal toxicity was associated with worse daily rectal dosimetry compared to the treatment plan. 1. Introduction Hypofractionated treatment regimens for clinically localized prostate cancer remain a topic of debate as large prospective trials such as RTOG 0415 continue to mature. The large retrospective series from Cleveland Clinic as well as recently published phase III data by Arcangeli et al. indicate that hypofractionated RT is well-tolerated and offers high rates of biochemical control [1, 2]. However, most published series focus primarily on patients with a relatively low risk of lymph node involvement and have, therefore, restricted treatment to the prostate and seminal vesicles only. Traditionally, patients with high-risk prostate cancer receive whole-pelvic radiotherapy (WPRT), and such regimens have formed the backbone of large-scale clinical trials such as RTOG 8531, RTOG 9202, and EORTC 22863 [3–6]. Though conventionally fractionated WPRT has been safely delivered on a number of clinical trials, little data exists concerning treatment of the pelvic lymph nodes as part of a hypofractionated regimen. To date, there has only been one phase III trial which utilized hypofractionated WPRT for patients with high-risk disease [7]. While the short-term toxicity results of this study are promising, a detailed report of the long-term toxicities is pending. Advances in radiation delivery such as intensity-modulated radiotherapy (IMRT) and image-guided
No Major Change in vCJD Agent Strain after Secondary Transmission via Blood Transfusion
Matthew T. Bishop, Diane L. Ritchie, Robert G. Will, James W. Ironside, Mark W. Head, Val Thomson, Moira Bruce, Jean C. Manson
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002878
Abstract: Background The identification of transmission of variant Creutzfeldt-Jakob disease (vCJD) by blood transfusion has prompted investigation to establish whether there has been any alteration in the vCJD agent following this route of secondary transmission. Any increase in virulence or host adaptation would require a reassessment of the risk analyses relating to the possibility of a significant secondary outbreak of vCJD. Since there are likely to be carriers of the vCJD agent in the general population, there is a potential for further infection by routes such as blood transfusion or contaminated surgical instruments. Methodology We inoculated both wild-type and transgenic mice with material from the first case of transfusion associated vCJD infection. Principal Findings The strain transmission properties of blood transfusion associated vCJD infection show remarkable similarities to the strain of vCJD associated with transmission from bovine spongiform encephalopathy (BSE). Conclusions Although it has been hypothesized that adaptation of the BSE agent through secondary passage in humans may result in a greater risk of onward transmission due to an increased virulence of the agent for humans, our data presented here in two murine models suggest no significant alterations to transmission efficiency of the agent following human-to-human transmission of vCJD.
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