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let g be a connected simple (molecular) graph. the distance d(u, v) between two vertices u and v of g is equal to the length of a shortest path that connects u and v. in this paper we compute some distance based topological indices of h-phenylenic nanotorus. at first we obtain an exactformula for the wiener index. as application we calculate the schultz index and modified schultz index of this ...

background: doppler indices of umbilical artery are used as indicator of fetal well being. objective: to compare doppler parameters of umbilical artery including pulsatility index (pi) and resistance index (ri) in patients with preeclampsia with those of normal pregnancies and to evaluate the diagnostic characteristics of these parameters in preeclampsia. materials and methods: in a case contro...

let $g$ be a connected graph, and let $d[g]$ denote the double graph of $g$. in this paper, we first derive closed-form formulas for different distance based topological indices for $d[g]$ in terms of that of $g$. finally, as illustration examples, for several special kind of graphs, such as, the complete graph, the path, the cycle, etc., the explicit formulas for some distance based topologica...

drought as a natural but temporary imbalance of water availability is the interaction between natural environment and human life resulting in diminished water resources availability and reduced carrying capacity of the ecosystems. drought indices are essential elements for an efficient drought monitoring system. these indices make the transforming information of climatic anomalies easier and al...

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the padmakar-ivan (pi) index is a wiener-szeged-like topological index which reflectscertain structural features of organic molecules. the pi index of a graph g is the sum of alledges uv of g of the number of edges which are not equidistant from the vertices u and v. inthis paper we obtain the second and third extremals of catacondensed hexagonal systems withrespect to the pi index.