3,375 research outputs found
Self-Similar Random Processes and Infinite-Dimensional Configuration Spaces
We discuss various infinite-dimensional configuration spaces that carry
measures quasiinvariant under compactly-supported diffeomorphisms of a manifold
M corresponding to a physical space. Such measures allow the construction of
unitary representations of the diffeomorphism group, which are important to
nonrelativistic quantum statistical physics and to the quantum theory of
extended objects in d-dimensional Euclidean space. Special attention is given
to measurable structure and topology underlying measures on generalized
configuration spaces obtained from self-similar random processes (both for d =
1 and d > 1), which describe infinite point configurations having accumulation
points
Indigenous and institutional profile: Limpopo River Basin
River basins / Water resource management / History / Institutions / Social aspects / Legal aspects
SAMBA: Superconducting antenna-coupled, multi-frequency, bolometric array
We present a design for a multipixel, multiband (100 GHz, 200 GHz and 400 GHz) submillimeter instrument: SAMBA (Superconducting Antenna-coupled, Multi-frequency, Bolometric Array). SAMBA uses slot antenna coupled bolometers and microstrip filters. The concept allows for a much more compact, multiband imager compared to a comparable feedhorn-coupled bolometric system. SAMBA incorporates an array of slot antennas, superconducting transmission lines, a wide band multiplexer and superconducting transition edge bolometers. The transition-edge film measures the millimeter-wave power deposited in the resistor that terminates the transmission line
Some Variations on Maxwell's Equations
In the first sections of this article, we discuss two variations on Maxwell's
equations that have been introduced in earlier work--a class of nonlinear
Maxwell theories with well-defined Galilean limits (and correspondingly
generalized Yang-Mills equations), and a linear modification motivated by the
coupling of the electromagnetic potential with a certain nonlinear Schroedinger
equation. In the final section, revisiting an old idea of Lorentz, we write
Maxwell's equations for a theory in which the electrostatic force of repulsion
between like charges differs fundamentally in magnitude from the electrostatic
force of attraction between unlike charges. We elaborate on Lorentz'
description by means of electric and magnetic field strengths, whose governing
equations separate into two fully relativistic Maxwell systems--one describing
ordinary electromagnetism, and the other describing a universally attractive or
repulsive long-range force. If such a force cannot be ruled out {\it a priori}
by known physical principles, its magnitude should be determined or bounded
experimentally. Were it to exist, interesting possibilities go beyond Lorentz'
early conjecture of a relation to (Newtonian) gravity.Comment: 26 pages, submitted to a volume in preparation to honor Gerard Emch
v. 2: discussion revised, factors of 4\pi corrected in some equation
Integrated Focal Plane Arrays for Millimeter-wave Astronomy
We are developing focal plane arrays of bolometric detectors for sub-millimeter and millimeter-wave astrophysics. We propose a flexible array architecture using arrays of slot antennae coupled via low-loss superconducting Nb transmission line to microstrip filters and antenna-coupled bolometers. By combining imaging and filtering functions with transmission line, we are able to realize unique structures such as a multi-band polarimeter and a planar, dispersive spectrometer. Micro-strip bolometers have significantly smaller active volume than
standard detectors with extended absorbers, and can realize higher sensitivity and speed of response. The integrated array has natural immunity to stray radiation or spectral leaks, and minimizes the suspended mass operating at 0.1 - 0.3 K. We also discuss future space-borne spectroscopy and polarimetry applications
Gesture analysis for physics education researchers
Systematic observations of student gestures can not only fill in gaps in
students' verbal expressions, but can also offer valuable information about
student ideas, including their source, their novelty to the speaker, and their
construction in real time. This paper provides a review of the research in
gesture analysis that is most relevant to physics education researchers and
illustrates gesture analysis for the purpose of better understanding student
thinking about physics.Comment: 14 page
A Search for Cosmic Microwave Background Anisotropies on Arcminute Scales with Bolocam
We have surveyed two science fields totaling one square degree with Bolocam
at 2.1 mm to search for secondary CMB anisotropies caused by the Sunyaev-
Zel'dovich effect (SZE). The fields are in the Lynx and Subaru/XMM SDS1 fields.
Our survey is sensitive to angular scales with an effective angular multipole
of l_eff = 5700 with FWHM_l = 2800 and has an angular resolution of 60
arcseconds FWHM. Our data provide no evidence for anisotropy. We are able to
constrain the level of total astronomical anisotropy, modeled as a flat
bandpower in C_l, with frequentist 68%, 90%, and 95% CL upper limits of 590,
760, and 830 uKCMB^2. We statistically subtract the known contribution from
primary CMB anisotropy, including cosmic variance, to obtain constraints on the
SZE anisotropy contribution. Now including flux calibration uncertainty, our
frequentist 68%, 90% and 95% CL upper limits on a flat bandpower in C_l are
690, 960, and 1000 uKCMB^2. When we instead employ the analytic spectrum
suggested by Komatsu and Seljak (2002), and account for the non-Gaussianity of
the SZE anisotropy signal, we obtain upper limits on the average amplitude of
their spectrum weighted by our transfer function of 790, 1060, and 1080
uKCMB^2. We obtain a 90% CL upper limit on sigma8, which normalizes the power
spectrum of density fluctuations, of 1.57. These are the first constraints on
anisotropy and sigma8 from survey data at these angular scales at frequencies
near 150 GHz.Comment: 68 pages, 17 figures, 2 tables, accepted for publication in Ap
Quantum chaos, random matrix theory, and statistical mechanics in two dimensions - a unified approach
We present a theory where the statistical mechanics for dilute ideal gases
can be derived from random matrix approach. We show the connection of this
approach with Srednicki approach which connects Berry conjecture with
statistical mechanics. We further establish a link between Berry conjecture and
random matrix theory, thus providing a unified edifice for quantum chaos,
random matrix theory, and statistical mechanics. In the course of arguing for
these connections, we observe sum rules associated with the outstanding
counting problem in the theory of braid groups. We are able to show that the
presented approach leads to the second law of thermodynamics.Comment: 23 pages, TeX typ
On the virial coefficients of nonabelian anyons
We study a system of nonabelian anyons in the lowest Landau level of a strong
magnetic field. Using diagrammatic techniques, we prove that the virial
coefficients do not depend on the statistics parameter. This is true for all
representations of all nonabelian groups for the statistics of the particles
and relies solely on the fact that the effective statistical interaction is a
traceless operator.Comment: 9 pages, 3 eps figure
New CMB Power Spectrum Constraints from MSAMI
We present new cosmic microwave background (CMB) anisotropy results from the
combined analysis of the three flights of the first Medium Scale Anisotropy
Measurement (MSAM1). This balloon-borne bolometric instrument measured about 10
square degrees of sky at half-degree resolution in 4 frequency bands from 5.2
icm to 20 icm with a high signal-to-noise ratio. Here we present an overview of
our analysis methods, compare the results from the three flights, derive new
constraints on the CMB power spectrum from the combined data and reduce the
data to total-power Wiener-filtered maps of the CMB. A key feature of this new
analysis is a determination of the amplitude of CMB fluctuations at . The analysis technique is described in a companion paper by Knox.Comment: 9 pages, 6 included figure
- …