the wiener polarity index wp(g) of a molecular graph g of order n is the number ofunordered pairs of vertices u, v of g such that the distance d(u,v) between u and v is 3. in anearlier paper, some extremal properties of this graph invariant in the class of catacondensedhexagonal systems and fullerene graphs were investigated. in this paper, some new bounds forthis graph invariant are presented....

introduction :  despite  recent  advances  in  treatment  of  oral  cancer,  it  still causes high rates of mortality and morbidity worldwide. delays in diagnosis and treatment of these cancers greatly affect the prognosis.  this study aimed to assess the treatment delay and its relation to diagnostic delay among oral cancer patients in tehran, iran. materials and methods : we studied 100 patie...

‎We consider the oscillator group equipped with‎ ‎a biinvariant Lorentzian metric‎. ‎Some geometrical properties of this space and the harmonicity properties of left-invariant vector fields on this space are determined‎. ‎In some cases‎, ‎all these vector fields are critical points for the energy functional‎ ‎restricted to vector fields‎. ‎Left-invariant vector fields defining harmonic maps are...

This paper addresses a new fractional order infectious disease model with saturated incidence and time delay. In the model, isolated population asymptomatic infected are considered. The invariant region positive analysis of solution established. Next, basic reproduction number is obtained by next-generation matrix method, sufficient conditions for local asymptotic stability arbitrary delays pro...

for a simple connected graph $g$ with $n$-vertices having laplacian eigenvalues‎ ‎$mu_1$‎, ‎$mu_2$‎, ‎$dots$‎, ‎$mu_{n-1}$‎, ‎$mu_n=0$‎, ‎and signless laplacian eigenvalues $q_1‎, ‎q_2,dots‎, ‎q_n$‎, ‎the laplacian-energy-like invariant($lel$) and the incidence energy ($ie$) of a graph $g$ are respectively defined as $lel(g)=sum_{i=1}^{n-1}sqrt{mu_i}$ and $ie(g)=sum_{i=1}^{n}sqrt{q_i}$‎. ‎in th...

We investigate shift invariant subspaces of $L^2(G)$, where $G$ is a locally compact abelian group. We show that every shift invariant space can be decomposed as an orthogonal sum of spaces each of which is generated by a single function whose shifts form a Parseval frame. For a second countable locally compact abelian group $G$ we prove a useful Hilbert space isomorphism, introduce range funct...

This paper presents methods for estimating time delay margin for adaptive control of input delay systems with almost linear structured uncertainty and a step input reference command signal. The bounded linear stability analysis method seeks to represent an adaptive law by a locally bounded linear approximation within a time window. The time delay margin of this input delay system represents a l...

background: the purpose of this study was to compare patient delay, diagnosis delay and treatment delay in breast cancer patients of selected public and private health centers in tehran, iran. methods: in this cross-sectional study, female patients with newly diagnosed breast cancer in a public medical complex and a private breast clinic within one year were included. patient delay was consider...