in this paper some upper and lower bounds for the greatest eigenvalues of the pi and vertex pimatrices of a graph g are obtained. those graphs for which these bounds are best possible arecharacterized.

we present a detailed analysis of the static tuning characteristics of three section tunable distributed bragg reflector (dbr) laser. the analysis is based on the transfer matrix method (tmm), transmission line and scattering theory. the key feature of the analysis is the use of modified oscillation condition. with the exact oscillation condition, the static tuning characteristics such as thres...

we denote by $ls[n](t,k,v)$ a large set of $t$-$(v,k,lambda)$ designs of size $n$, which is a partition of all  $k$-subsets ofa $v$-set into $n$ disjoint  $t$-$(v,k,lambda)$ designs and$n={v-t choose k-t}/lambda$.   we use the notation$n(t,v,k,lambda)$ as the maximum possible number of mutuallydisjoint cyclic $t$-$(v,k,lambda)$designs. in this paper we givesome new bounds for $n(2,29,4,3)$ and ...

the paper presents lower and upper bounds on the number of parity check digits required for a linear code that detects solid bursts of length $b$ or less and simultaneously any $e$ or less random errors. an example of such a code is also provided. further, codes capable of detecting and simultaneously correcting such errors have also been dealt with.

in this paper, we consider an arbitrary binary polynomial sequence {a_n} and then give a lower triangular matrix representation of this sequence. as main result, we obtain a factorization of the innite generalized pascal matrix in terms of this new matrix, using a riordan group approach. further some interesting results and applications are derived.

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although pyrimethamine (tindurin™) appears to be effective in the prevention and treatment of some infectious diseases, very little information exists on its unpredictable properties. we design this study to evaluate its anti-tumoral effect on a model of cell line. methods: the cytotoxic influence of pyrimethamine on prostate cell line was investigated using an in vitro colometric assay. the po...

in this paper data were collected from 120 farmers in north khorassan province for the two periods (2005-2007) in order to survey the role of rain-fed lentil risk profile for designing an insurance model. to evaluate looses of each risk, risk frequency, risk impact criteria’s as well as risk matrix were used. results showed that low risk was the largest risk area. during study period, a decreas...