1,304 research outputs found
Photometric observations of recent comets
Infrared observations of comet Bennett, Kohoutek, Bradfield, and Encke are analyzed with emphasis on the detection of the silicate emission feature. Results are summarized
Corrections and acknowledgment for ``Local limit theory and large deviations for supercritical branching processes''
Corrections and acknowledgment for ``Local limit theory and large deviations
for supercritical branching processes'' [math.PR/0407059]Comment: Published at http://dx.doi.org/10.1214/105051606000000574 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
T. E. Harris and branching processes
T. E. Harris was a pioneer par excellence in many fields of probability
theory. In this paper, we give a brief survey of the many fundamental
contributions of Harris to the theory of branching processes, starting with his
doctoral work at Princeton in the late forties and culminating in his
fundamental book "The Theory of Branching Processes," published in 1963.Comment: Published in at http://dx.doi.org/10.1214/10-AOP599 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Infrared observations of P/Halley and P/Encke
Broadband optical/infrared photometers responding from 0.5 to 23 microns mounted on the Univ. of Minnesota (UM) O'Brien 76-cm telescope, Wyoming Infrared Observatory 234-cm telescope, and UM's Mount Lemmon Infrared Observatory 152-cm telescope were used to measure comet Halley more than 30 times between 12 Dec. 1985 to 6 May 1986. The Wyoming system was used to measure P/Encke on 24 Jul. 1987. The equipment and observations of Halley were fully described by Gehrz and Ney. Conclusions based on a preliminary analysis of the Halley and P/Encke data are reported
02-01 "Economic Analysis in Environmental Reviews of Trade Agreements: Assessing the North American Experience"
Beginning in the late 1990s, Canada and the United States began requiring "Environmental Reviews (ERs)" of all trade agreements to be negotiated by each government. This paper, commissioned by the North American Commission for Environmental Cooperation, outlines how ERs have evolved in North America, and evaluates the different methodological approaches that have been employed in ERs thus far. We show that the ERs conducted to date have an encouraging number of strengths that can be built upon. However, we also establish that the art of conducting ERs is still in its infancy. We identify four limitations with the methodological approaches that have been employed in the most recent ERs. Based on an analysis of these limitations, we propose four ways to improve how ERs are conducted in the future:
Large deviations for a damped telegraph process
In this paper we consider a slight generalization of the damped telegraph
process in Di Crescenzo and Martinucci (2010). We prove a large deviation
principle for this process and an asymptotic result for its level crossing
probabilities (as the level goes to infinity). Finally we compare our results
with the analogous well-known results for the standard telegraph process
Sensitive SQUID magnetometry for studying nano-magnetism
The superconducting quantum interference device (SQUID) magnetometer is one
of the most sensitive experimental techniques to magnetically characterize
samples with high sensitivity. Here we present a detailed discussion of
possible artifacts and pitfalls characteristic for commercial SQUID
magnetometers. This includes intrinsic artifacts which stem from the inherent
design of the magnetometer as well as potential issues due to the user. We
provide some guidelines how to avoid and correct these, which is of particular
importance when the proper magnetization of nano-scale objects shall be
established in cases where its response is dwarfed by that of the substrate it
comes with, a situation frequently found in the field of nano-magnetism.Comment: 18 pages PRB style, 13 figures (1st and 3rd wrongly reproduced, ???
High yield fusion in a Staged Z-pinch
We simulate fusion in a Z-pinch; where the load is a xenon-plasma liner
imploding onto a deuterium-tritium plasma target and the driver is a 2 MJ, 17
MA, 95 ns risetime pulser. The implosion system is modeled using the dynamic,
2-1/2 D, radiation-MHD code, MACH2. During implosion a shock forms in the Xe
liner, transporting current and energy radially inward. After collision with
the DT, a secondary shock forms pre-heating the DT to several hundred eV.
Adiabatic compression leads subsequently to a fusion burn, as the target is
surrounded by a flux-compressed, intense, azimuthal-magnetic field. The
intense-magnetic field confines fusion -particles, providing an
additional source of ion heating that leads to target ignition. The target
remains stable up to the time of ignition. Predictions are for a neutron yield
of and a thermonuclear energy of 84 MJ, that is, 42 times
greater than the initial, capacitor-stored energy
Photometer dewar system for NASA C141 airborne telescope (Kuiper Flying Observatory)
The design, calibration, and testing of a photometer to be used in an airborne telescope is described. A description of the cryogenics of the photometer is given, and photographs and blueprints of the photometer are included. The photometer is designed with a focal plane beam switching system so that the airplane telescope can be used in a normal optical mode at the bent Cassegrain focus and with the photometer operating in the pressurized cabin of the airplane. The concept was to produce a system which could be used in almost the same manner as ground based infrared photometers and dewars of the O'Brien Observatory at the University of Minnesota
Importance Sampling for multi-constraints rare event probability
Improving Importance Sampling estimators for rare event probabilities
requires sharp approx- imations of the optimal density leading to a nearly
zero-variance estimator. This paper presents a new way to handle the estimation
of the probability of a rare event defined as a finite intersection of subset.
We provide a sharp approximation of the density of long runs of a random walk
condi- tioned by multiples constraints, each of them defined by an average of a
function of its summands as their number tends to infinity.Comment: Conference pape
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