background & aims of the study: corrosion and scaling play undesirable effects on transmission and distribution system of drinking water. the aim of this study was to assess the corrosion and scaling potential of drinking water resources in babol city. materials and methods: totally, 54 water samples were collected from 27 wells in spring and autumn. calciu m hardness, ph, total alkalinity, tot...

this research was conducted under greenhouse conditions to evaluate the optimum combination of irrigation and fertilizer levels to attain the best yield and quality of tomato crop. the experiment was conducted by using a split-plot design with three replicates. irrigation levels were applied to the main plots and fertilizer levels to the sub-plots. for each experimental unit, the irrigation lev...

purpose: to study the distribution of ocular higher-order aberrations (hoas) and mesopic pupil size in individuals screened for refractive surgery. methods: ocular hoas and mesopic pupil size were studied in 2458 eyes of 1240 patients with myopia, simple myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, simple hyperopic astigmatism and compound hype...

The inflation $G_{I}$ of a graph $G$ with $n(G)$ vertices and $m(G)$ edges is obtained from $G$ by replacing every vertex of degree $d$ of $G$ by a clique, which is isomorph to the complete graph $K_{d}$, and each edge $(x_{i},x_{j})$ of $G$ is replaced by an edge $(u,v)$ in such a way that $uin X_{i}$, $vin X_{j}$, and two different edges of $G$ are replaced by non-adjacent edges of $G_{I}$. T...

‎Let $G$ be a finite and simple graph with vertex set $V(G)$‎. ‎A nonnegative signed total Roman dominating function (NNSTRDF) on a‎ ‎graph $G$ is a function $f:V(G)rightarrow{-1‎, ‎1‎, ‎2}$ satisfying the conditions‎‎that (i) $sum_{xin N(v)}f(x)ge 0$ for each‎ ‎$vin V(G)$‎, ‎where $N(v)$ is the open neighborhood of $v$‎, ‎and (ii) every vertex $u$ for which‎ ‎$f(u...

A {em Roman dominating function} on a graph $G$ is a function $f:V(G)rightarrow {0,1,2}$ satisfying the condition that every vertex $u$ for which $f(u)=0$ is adjacent to at least one vertex $v$ for which $f(v)=2$. A {em total Roman dominating function} is a Roman dominating function with the additional property that the subgraph of $G$ induced by the set of all vertices of positive weight has n...

background wastewater effluent in hospitals has been increasing during the recent decades due to developments in medical services and products. objectives this study aimed to investigate the qualitative parameters of effluent wastewater in hospitals affiliated to babol university of medical sciences (bums). materials and methods four hospitals were included and their wastewater effluent was stu...

In this paper we consider three questions. Why do only some firms enter export markets? What are the benefits to the firm from export market entry? Why do some of these firms exit the market at a future date? Using data on UK manufacturing firms from 1988 to 2002 we find evidence that information spillovers between firms can raise the probability of entry and for a matched sample of firms there...