30,714 research outputs found
Microscopes and computers combined for analysis of chromosomes
Scanning machine CHLOE, developed for photographic use, is combined with a digital computer to obtain quantitative and statistically significant data on chromosome shapes, distribution, density, and pairing. CHLOE permits data acquisition about a chromosome complement to be obtained two times faster than by manual pairing
Saddlepoint approximation for moment generating functions of truncated random variables
We consider the problem of approximating the moment generating function (MGF)
of a truncated random variable in terms of the MGF of the underlying (i.e.,
untruncated) random variable. The purpose of approximating the MGF is to enable
the application of saddlepoint approximations to certain distributions
determined by truncated random variables. Two important statistical
applications are the following: the approximation of certain multivariate
cumulative distribution functions; and the approximation of passage time
distributions in ion channel models which incorporate time interval omission.
We derive two types of representation for the MGF of a truncated random
variable. One of these representations is obtained by exponential tilting. The
second type of representation, which has two versions, is referred to as an
exponential convolution representation. Each representation motivates a
different approximation. It turns out that each of the three approximations is
extremely accurate in those cases ``to which it is suited.'' Moreover, there is
a simple rule of thumb for deciding which approximation to use in a given case,
and if this rule is followed, then our numerical and theoretical results
indicate that the resulting approximation will be extremely accurate.Comment: Published at http://dx.doi.org/10.1214/009053604000000689 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The structural response of unsymmetrically laminated composite cylinders
The responses of an unsymmetrically laminated fiber-reinforced composite cylinder to an axial compressive load, a torsional load, and the temperature change associated with cooling from the processing temperature to the service temperature are investigated. These problems are considered axisymmetric and the response is studied in the context of linear elastic material behavior and geometrically linear kinematics. Four different laminates are studied: a general unsymmetric laminate; two unsymmetric but more conventional laminates; and a conventional quasi-isotropic symmetric laminate. The responses based on closed-form solutions for different boundary conditions are computed and studied in detail. Particular emphasis is directed at understanding the influence of elastic couplings in the laminates. The influence of coupling decreased from a large effect in the general unsymmetric laminate, to practically no effect in the quasi-isotropic laminate. For example, the torsional loading of the general unsymmetric laminate resulted in a radial displacement. The temperature change also caused a significant radial displacement to occur near the ends of the cylinder. On the other hand, the more conventional unsymmetric laminate and the quasi-isotropic cylinder did not deform radially when subjected to a torsional load. From the results obtained, it is clear the degree of elastic coupling can be controlled and indeed designed into a cylinder, the degree and character of the coupling being dictated by the application
Hardware proofs using EHDM and the RSRE verification methodology
Examined is a methodology for hardware verification developed by Royal Signals and Radar Establishment (RSRE) in the context of the SRI International's Enhanced Hierarchical Design Methodology (EHDM) specification/verification system. The methodology utilizes a four-level specification hierarchy with the following levels: functional level, finite automata model, block model, and circuit level. The properties of a level are proved as theorems in the level below it. This methodology is applied to a 6-bit counter problem and is critically examined. The specifications are written in EHDM's specification language, Extended Special, and the proofs are improving both the RSRE methodology and the EHDM system
Thermal Control Characteristics of a Diffuse Bladed, Specular Base Louver System Status Report, Jul. - Dec. 1967
Heat transfer, and thermal control characteristics of diffuse bladed louver system for spacecraf
Neutrino Physics and Nuclear Axial Two-Body Interactions
We consider the counter-term describing isoscalar axial two-body currents in
the nucleon-nucleon interaction, L1A, in the effective field theory approach.
We determine this quantity using the solar neutrino data. We investigate the
variation of L1A when different sets of data are used.Comment: 8 pages with 4 figures. To be published in the Proceedings of the
Conference "Blueprints For The Nucleus: From First Principles to Collective
Motion" held at Feza Gursey Institute, Istanbul, Turkey; May 17 -22, 200
Thermal control characteristics of a diffuse bladed specular base louver system Final report
Diffuse bladed specular base louver system for spacecraft temperature contro
Analysis of heating rates and forces on bodies subject to rocket exhaust plume impingement
Computer programs and engineering methods for calculating heating rates and forces in jet plume impingement problem
- …