2,678 research outputs found
Cliffordization, Spin and Fermionic Star Products
Deformation quantization is a powerful tool for quantizing theories with
bosonic and fermionic degrees of freedom. The star products involved generate
the mathematical structures which have recently been used in attempts to
analyze the algebraic properties of quantum field theory. In the context of
quantum mechanics they provide a canonical quantization procedure for systems
with either bosonic of fermionic degrees of freedom. We illustrate this
procedure for a number a physical examples, including bosonic, fermionic and
supersymmetric oscillators. We show how non-relativistic and relativistic
particles with spin can be naturally described in this framework.Comment: 21 page
Derivation of the total twist from Chern-Simons theory
The total twist number, which represents the first non-trivial Vassiliev knot
invariant, is derived from the second order expression of the Wilson loop
expectation value in the Chern-Simons theory. Using the well-known fact that
the analytical expression is an invariant, a non-recursive formulation of the
total twist based on the evaluation of knot diagrams is constructed by an
appropriate deformation of the knot line in the three-dimensional Euclidian
space. The relation to the original definition of the total twist is
elucidated.Comment: 26 page
Star Products and Geometric Algebra
The formalism of geometric algebra can be described as deformed super
analysis. The deformation is done with a fermionic star product, that arises
from deformation quantization of pseudoclassical mechanics. If one then extends
the deformation to the bosonic coefficient part of superanalysis one obtains
quantum mechanics for systems with spin. This approach clarifies on the one
hand the relation between Grassmann and Clifford structures in geometric
algebra and on the other hand the relation between classical mechanics and
quantum mechanics. Moreover it gives a formalism that allows to handle
classical and quantum mechanics in a consistent manner.Comment: 21 page
Seeing Earth's Orbit in the Stars: Parallax and Aberration
During the 17th century the idea of an orbiting and rotating Earth became
increasingly popular, but opponents of this view continued to point out that
the theory had observable consequences that had never, in fact, been observed.
Why, for instance, had astronomers failed to detect the annual parallax of the
stars that must occur if Earth orbits the Sun? To address this problem,
astronomers of the 17th and18th centuries sought to measure the annual parallax
of stars using telescopes. None of them succeeded. Annual stellar parallax was
not successfully measured until 1838, when Friedrich Bessel detected the
parallax of the star 61 Cygni. But the early failures to detect annual stellar
parallax led to the discovery of a new (and entirely unexpected) phenomenon:
the aberration of starlight. This paper recounts the story of the discovery of
stellar aberration. It is accompanied by a set of activities and computer
simulations that allow students to explore this fascinating historical episode
and learn important lessons about the nature of science.Comment: 10 pages, 5 figures, submitted to The Physics Teache
Leduc-Righi effect in superconductors with nontrivial density of states
Increasing of electronic thermal conductivity of superconductor in the model
with nontrivial density of states was considered. The electronic thermal
conductivity K(T) of SC in the presence of external magnetic field was
investigated. It was shown that if symmetrical part of quasiparticle scattering
rate less than cyclotron energy observed mechanism of increasing K(T) can be
separated from connected with asymmetric electronic scattering effects another
one.Comment: 5 pages, RevTe
Sources Of Student Engagement In Introductory Physics For Life Sciences
We explore the sources of student engagement with curricular content in an Introductory Physics for Life Science (IPLS) course at Swarthmore College. Do IPLS students find some life-science contexts more interesting than others, and, if so, what are the sources of these differences? We draw on three sources of student data to answer this question: (1) quantitative survey data illustrating how interested students were in particular contexts from the curriculum, (2) qualitative survey data in which students describe the source of their interest in these particular contexts, and (3) interview data in which students reflect on the contexts that were and were not of interest to them. We find that examples that make interdisciplinary connections with students’ other coursework in biology and chemistry, and examples that make connections to what students perceive to be the “real world,” are particularly effective at fostering interest. More generally, students describe being deeply engaged with contexts that foster a sense of coherence or have personal meaning to them. We identify various “engagement pathways” by which different life-science students engage with IPLS content, and suggest that a curriculum needs to be flexible enough to facilitate these different pathways
The Case for Physician Direction in Health Plans
Advanced managed care organizations limit costs by having nonphysician managers make medical management decisions. Physicians should be included on the board of medical managers to assurse that the patients\u27 best interests are considered when management decisions are made
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