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11.
P F Renshaw J C Haselgrove L Bolinger B Chance J S Leigh 《Magnetic resonance imaging》1986,4(3):193-198
It has recently been demonstrated that NMR imaging can be used to record the distribution of lithium. We now report on the parameters pertinent to this imaging. Specifically, the relaxation of Li in aqueous solution, in agarose gel, and in vivo has been investigated. In the latter case, both the longitudinal and transverse relaxations were biexponential, consistent with the behavior expected for a spin 3/2 quadrupole relaxed nucleus. The overall relaxation rate was quite slow in vivo with T'1 = 3.5 sec and T'1 = 6.6 sec. 相似文献
12.
Communicated by J.M. Howie 相似文献
13.
Chow JY Davids K Button C Shuttleworth R Renshaw I Araújo D 《Nonlinear dynamics, psychology, and life sciences》2006,10(1):71-103
Team sport competition can be characterized as a complex adaptive system in which concepts from nonlinear dynamics can provide a sound theoretical framework to understand emergent behavior such as movement coordination and decision making in game play. Nonlinear Pedagogy is presented as a methodology for games teaching, capturing how phenomena such as movement variability, self-organization, emergent decision making, and symmetry-breaking occur as a consequence of interactions between agent-agent and agent-environment constraints. Empirical data from studies of basketball free-throw shooting and dribbling are used as task vehicles to exemplify how nonlinear phenomena characterize game play in sport. In this paper we survey the implications of these data for Nonlinear Pedagogy, focusing particularly on the manipulation of constraints in team game settings. The data and theoretical modeling presented in this paper provide a rationale in nonlinear dynamics for the efficacy of a prominent model of game play teaching, Teaching Games for Understanding approach. 相似文献
14.
We investigate the modelling of mortality improvement rates and the feasibility of projecting mortality improvement rates (as opposed to projecting mortality rates), using parametric predictor structures that are amenable to simple time series forecasting. This leads to our proposing a parallel dual approach to the direct parametric modelling and projecting of mortality rates. Comparisons of simulated life expectancy predictions (by the cohort method) using the England and Wales population mortality experiences for males and females under a variety of controlled data trimming exercises are presented in detail and comparisons are also made between the parallel modelling approaches. 相似文献
15.
In this paper an alternative approach for measurement of στ product for 4
F
3/2→4
I
11/2 transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator
and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable.
The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is
measured by Gaussian fit to the intensity profiles of the pump beam. The value of στ product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple
method for direct measurement of στ product of laser crystals. 相似文献
16.
The concept of a weak factorization system has been studied extensively in homotopy theory and has recently found an application in one of the proofs of the celebrated flat cover conjecture, categorical versions of which have been presented by a number of authors including Rosický. One of the main aims of this paper is to draw attention to this interesting concept and to initiate a study of these systems in relation to flatness of S-acts and related concepts. 相似文献
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19.
This paper provides a comparative investigation of simulation strategies for measuring the longevity risk associated with
predictions of mortality rates and derived estimates of life expectancy. The study considers the Lee–Carter framework and
a generalised linear Poisson model for representing the dynamics of mortality, as well as enhancements that allow for joint
modelling of the dispersion and the effect of using a negative binomial rather than a Poisson assumption.
相似文献
20.
Summary Until now, denumerable Markov processes with instantaneous states have not been extensively considered, and so in this paper we present a detailed examination of the conservative uni-instantaneous (CUI) case. We determine criteria for the existence and uniqueness of a specific CUI pregenerator, and consider the general problem of constructing CUI processes. 相似文献