The parameters determine waves energy in shallow water zone that pronounces the crucial influence on abrasion of both natural and artificially paved banks. The effort to re-development of the relations was found as absolutely necessary for waves energy calculations. Substantial benefit of the work is found not only in enabling the use of computers while avoiding time-consuming and difficult application of diagrams, but namely in recent recognition that the calculation results showed a risk of underestimate the real impact of wind-induced waves. In some cases, the calculations respecting the above standard produce lower values of waves height and time-period and thus also lower values of wave energy., Tamara Spanilá and Karel Jahoda., and Obsahuje bibliografické odkazy
Let $p$ be a prime. We assign to each positive number $k$ a digraph $G_{p}^{k}$ whose set of vertices is $\{1,2,\ldots ,p-1\}$ and there exists a directed edge from a vertex $a$ to a vertex $b$ if $a^k\equiv b \pmod {p}$. In this paper we obtain a necessary and sufficient condition for $G_{p}^{k_{1}}\simeq G_{p}^{k_{2}}$.
Toxoplasma gondii (Nicolle et Manceaux, 1908) is an intracellular parasite that can cause ongoing latent infection persisting for the duration of a non-definitive host's life. Affecting approximately one-third of the world's population, latent toxoplasmosis has been associated with neuropsychological outcomes and a previous report suggested an association between latent toxoplasmosis and adult height. Given the large number of people with latent toxoplasmosis and its potential associations with human height, we sought to better understand the association between latent toxoplasmosis and human morphology by evaluating seropositivity for T. gondii and multiple body measures reported in the National Health and Nutrition Examination Survey III (NHANES III) and in the more recent continuous NHANES data sets from the United States Centers for Disease Control and Prevention for which data on T. gondii are available. In these analyses, latent toxoplasmosis was not associated with any of the body measures assessed in the NHANES datasets even after taking into account interactions between latent toxoplasmosis and testosterone suggesting that in these samples, latent toxoplasmosis is not associated with adult morphology including height., Andrew N. Berrett, Shawn D. Gale, Lance D. Erickson, Bruce L. Brown, Dawson W. Hedges., and Obsahuje bibliografii
A power digraph, denoted by $G(n,k)$, is a directed graph with $\mathbb Z_{n}=\{0,1,\dots ,n-1\}$ as the set of vertices and $E=\{(a,b)\colon a^{k}\equiv b\pmod n\}$ as the edge set. In this paper we extend the work done by Lawrence Somer and Michal Křížek: On a connection of number theory with graph theory, Czech. Math. J. 54 (2004), 465–485, and Lawrence Somer and Michal Křížek: Structure of digraphs associated with quadratic congruences with composite moduli, Discrete Math. 306 (2006), 2174–2185. The heights of the vertices and the components of $G(n,k)$ for $n\geq 1$ and $k\geq 2$ are determined. We also find an expression for the number of vertices at a specific height. Finally, we obtain necessary and sufficient conditions on $n$ such that each vertex of indegree $0$ of a certain subdigraph of $G(n,k)$ is at height $q\geq 1$.
Let $\mathbb {Z}_n{\rm [i]}$ be the ring of Gaussian integers modulo $n$. We construct for $\mathbb {Z}_n{\rm [i]}$ a cubic mapping graph $\Gamma (n)$ whose vertex set is all the elements of\/ $\mathbb {Z}_n{\rm [i]}$ and for which there is a directed edge from $a \in \mathbb {Z}_n{\rm [i]}$ to $b \in \mathbb {Z}_n{\rm [i]}$ if $ b = a^3$. This article investigates in detail the structure of $\Gamma (n)$. We give suffcient and necessary conditions for the existence of cycles with length $t$. The number of $t$-cycles in $\Gamma _1(n)$ is obtained and we also examine when a vertex lies on a $t$-cycle of $\Gamma _2(n)$, where $\Gamma _1(n)$ is induced by all the units of $\mathbb {Z}_n{\rm [i]}$ while $\Gamma _2(n)$ is induced by all the zero-divisors of $\mathbb {Z}_n{\rm [i]}$. In addition, formulas on the heights of components and vertices in $\Gamma (n)$ are presented.