作者：
Fisher, Nicholas I.Hall, PeterProgram Leader
Applied and Industrial Statistics Division of Mathematics and Statistics Commonwealth Scientific and Industrial Research Organisation Lindfield New South Wales 2070 Australia. Professor
Department of Statistics Australian National University Canberra Australian Capital Territory 2601 Australia
Methods are proposed for constructing bootstrap confidence regions for the mean direction of a random p-dimensional unit vector X with an arbitrary unimodal distribution on the p sphere. The approach of this article d...
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Methods are proposed for constructing bootstrap confidence regions for the mean direction of a random p-dimensional unit vector X with an arbitrary unimodal distribution on the p sphere. The approach of this article differs from that of other authors in that it is based on pivotal statistics. A general pivotal method is introduced that produces a wide variety of confidence regions on general p-dimensional spheres; included are confidence cones and likelihood-based regions. It can readily be modified to incorporate extra assumptions about the underlying distribution, such as rotational symmetry. The general method leads to confidence pictures, which present information about the estimated posterior likelihood of mean orientation by shading spherical surfaces. An application is given to a sample of spherical cross-bed measurements. The methods extend to the case where X has random length, and to calculation of confidence regions for reference directions of axial bipolar or girdle distributions. [ABSTRACT FROM AUTHOR]
The boundary element (BE) technique is used to analyze the effect of defect structures upon desorption processes on two-dimensional chemically active surfaces. The standard BE algorithm for diffusion is modified to in...
The spread of AIDS by sexual contact is analyzed by a homogeneous mixing model. Using data for the epidemic in the U.S. homosexual population the infectivity of the virus is estimated. Behavioral responses to the epid...
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The spread of AIDS by sexual contact is analyzed by a homogeneous mixing model. Using data for the epidemic in the U.S. homosexual population the infectivity of the virus is estimated. Behavioral responses to the epidemic in the form of declining sexual interaction rates and/or infectivity of the virus are modelled. These analyses are used to explore the potential efficacy of measures for controlling the epidemic.
作者：
MCNICHOLS, RJDAVIS, CBRoger J. McNichols is a professor of industrial engineering at the University of Toledo (Department of Industrial Engineering
University of Toledo Toledo OH 43606). After receiving his Ph.D in industrial engineering from The Ohio State University he joined the faculty of Texas A and M University where he directed the Maintainability Engineering Graduate Program at Red River Army Depot. At UT he has served as associate dean of engineering and as chairman of the Systems engineering doctoral program. His research and consulting interests include reliability quality control manufacturing mathematical modeling and applied statistics. Charles B. Davis is an associate professor of mathematics at the University of Toledo (Department of Mathematics
University of Toledo Toledo OH 43606). After receiving his M.S. in mathematics and statistics and his Ph.D. in statistics from the University of New Mexico he joined the Mathematics Department at UT where he established the graduate program in statistics. His research and consulting interests include statistical modeling statistical computation simultaneous inference and data analysis.
Ground water monitoring presents interesting statistical challenges, including controlling the risk of entering compliance monitoring, incorporating all modes of inherent variability into the statistical model on whic...
Ground water monitoring presents interesting statistical challenges, including controlling the risk of entering compliance monitoring, incorporating all modes of inherent variability into the statistical model on which tests are based, and taming the detection limit problem, all while maintaining demonstrable sensitivity to real contamination. Some of these challenges exceed textbook statistics considerably, even when considered alone, and good solutions are scarce. When these challenges are combined, the task of developing good statistical procedures or good regulations can be formidable. This article presents a number of realities of ground water monitoring that should be considered when developing statistical procedures. Recommendations made for addressing these realities include the following: (1) the false positive rate should be controlled on a facility-wide basis, rather than per well or per parameter as required in the proposed regulation (40 CFR §264); (2) multiple comparisons with control procedures are preferable to analysis of variance (ANOVA) for controlling the overall false positive rate; (3) retests can be made an explicit part of the statistical procedure in order to increase power and decrease sensitivity to distribution shape assumptions; (4) commonly used simple methods of handling below detection limit data with parametric tests, including Cohen's procedure as implemented in the U.S. EPA's Technical Enforcement Guidance Document (TEGD), should probably be avoided; (5) the statistical properties of practical quantitation limits for non-naturally occurring compounds should be studied carefully; and (6) so long as the facility-wide false positive rate is controlled, better sensitivity to real contamination is obtained by monitoring fewer well-chosen parameters at a smaller number of well-chosen locations. An evaluation of the proposed revised §264 regulation with respect to these realities reveals that it seems to be a definite improvement over the
A three‐mode projection of the Navier–Stokes equations for nonlinear perturbations to an elliptical vortex is studied numerically. It is found that, as the Reynolds number increases, the perturbations undergo a sequ...
A three‐mode projection of the Navier–Stokes equations for nonlinear perturbations to an elliptical vortex is studied numerically. It is found that, as the Reynolds number increases, the perturbations undergo a sequence of period doublings leading to chaos according to the Feigenbaum scenario [J. Statis. Phys. 19, 25 (1978); Phys. Lett. 74 A, 375 (1979)].
Modular scintillation cameras are gamma cameras with relatively small crystal faces, a small number of photomultiplier tubes (PMTs), and independent processing electronics. Our prototypical module has a 10 cm square c...
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作者：
M. SteslickaM. RadnyS. G. DavisonQuantum Theory Group
Department of Applied Mathematics and Department of Physics University of Waterloo Waterloo Ontario Canada N2L?1 and Guelph-Waterloo Program for Graduate Work in Physics University of Guelph Guelph Ontario Canada N1G?1
The effective-range approximation is adopted to study surface states of a linear array of scattering centers. It is shown that, depending on the values of the scattering length and effective range for the surface atom...
The effective-range approximation is adopted to study surface states of a linear array of scattering centers. It is shown that, depending on the values of the scattering length and effective range for the surface atom, two, one, or zero surface states can exist in the forbidden energy gap. The possibility of a smooth transition from true (stationary) surface states to virtual (decaying) states is discussed. A comparison is also made with the crystal-potential approach.
Using recently developed methods in nonlinear dynamics, two hypotheses often advanced to account for recurrent outbreaks of childhood diseases such as measles are investigated. The first, maintenance of otherwise damp...
Using recently developed methods in nonlinear dynamics, two hypotheses often advanced to account for recurrent outbreaks of childhood diseases such as measles are investigated. The first, maintenance of otherwise damped oscillations by noise, appears incapable of reproducing essential features of the data. The second, cycles and chaos sustained by seasonal variation in contact rates gives qualitative and quantitative agreement between model and observation. It is concluded that nonlinear dynamics offers a methodology which may allow students of ecology and epidemiology to distinguish between competing mechanistic hypotheses.
New techniques are presented for the calculation of lower bounds to energies of atoms and ions. A combination of effective-field and intermediate-problem methods is used to seek intermediate operators which rapidly ap...
New techniques are presented for the calculation of lower bounds to energies of atoms and ions. A combination of effective-field and intermediate-problem methods is used to seek intermediate operators which rapidly approximate the lower spectrum of the full Hamiltonian. Effectiveness of the techniques is demonstrated by showing that very small-scale calculations suffice to free the ground state of Li from the continuum, and to approximate the Li+ ground state within 0.8%.
We examine a nontopological model for stable scalar solitons in 3+1 dimensions. Making the complex scalar field satisfy a local virial constraint we look into the possibility of obtaining nonsingular stationary soluti...
We examine a nontopological model for stable scalar solitons in 3+1 dimensions. Making the complex scalar field satisfy a local virial constraint we look into the possibility of obtaining nonsingular stationary solutions.
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