1. We describe an open source R package agTrend for analyzing regional trends of abundance from sites with uneven sample schedules. 2. The package agTrend uses an abundance summary approach to estimate trends. By considering abundance trends in this fashion, rather than a model parameter, we can easily augment missing observations to calculate aggregated abundance and trends. 3. The package use...

Self-diffusion in polymer solutions studied with pulsed-field gradient nuclear magnetic resonance (PFG NMR) is typically based either on a single self-diffusion coefficient, or a log-normal distribution of self-diffusion coefficients, or in some cases mixtures of these. Experimental data on polyethylene glycol (PEG) solutions and simulations were used to compare a model based on a gamma distrib...

1. Abstract Over three decades, metamodeling has been widely applied to design optimization problems to build a surrogate model of computation-intensive engineering models. The Kriging method has gained significant interests for developing the surrogate model. However, traditional Kriging methods, including the ordinary Kriging and the universal Kriging, use fixed polynomials basis functions to...

A simple and novel method is presented to approximate the distribution of the sum of independent, but not necessarily identical, lognormal random variables, by the lognormal distribution. It is shown that matching a short GaussHermite approximation of the moment generating function of the lognormal sum with that of the lognormal distribution leads to an accurate lognormal sum approximation. The...

The study of ionospheric scintillation belongs to the class of problems dealing with wave diffraction and propagation through a random medium, and its complete theoretical solution is presently not available. Approximate solutions or models, such as the 'thin phase diffraction screen model' and the 'Rytov solution for weak scintillation', have been proposed and do apply under restrictive condit...

Two recent experimental observations pose a challenge to many cortical models. First, the activity in the auditory cortex is sparse, and firing rates can be described by a lognormal distribution. Second, the distribution of nonzero synaptic strengths between nearby cortical neurons can also be described by a lognormal distribution. Here we use a simple model of cortical activity to reconcile th...

The physical causes for wide variation of Stokes shift values in emission spectra of tryptophan fluorophores in proteins have been proposed in the model of discrete states (Burstein, E. A., N. S. Vedenkina, and M. N. Ivkova. 1973. Photochem. Photobiol. 18:263-279; Burstein, E. A. 1977a. Intrinsic Protein Luminescence (The Nature and Application). In Advances in Science and Technology (Itogi Nau...

This note will look at ways of computing P(X>Y)where X is a distribution modeling survival (gamma, inverse gamma, Weibull, log-normal) and Y has a uniform distribution. Each of these can be computer in closed form in terms of common statistical functions. We begin with analytical calculations and then include software implementations in R to make some of the details more explicit. Finally, we g...

We analyze the ergodic capacity and epsilon-outage capacity of coherent optical links through the turbulent atmosphere. We consider the effects of log-normal amplitude fluctuations and Gaussian phase fluctuations, in addition to local oscillator shot noise, for both passive receivers and those employing active modal compensation of wavefront phase distortion. We study the effect of various para...