In this paper the periodic solutions of fourth order delay differential equation of the form $ddddot{x}(t)+adddot{x}(t)+f(ddot{x}(t-tau(t)))+g(dot{x}(t-tau(t)))+h({x}(t-tau(t)))=p(t)$  is investigated. Some new positive periodic criteria are given.  

In this work, we make an exhaustive study of the properties of the Green’s function related to the periodic boundary value problem Lax ≡ x′′ + a(t) x = 0, x(0) = x(T ), x′(0) = x′(T ), with a sign-changing potential a(t). Moreover, we obtain new explicit criteria that ensures that the maximum or anti-maximum principle holds for this equation. The given criteria complement previous results in th...

The purpose of this paper is to develop a generalized matrix Riccati technique for the selfadjoint matrixHamiltonian systemU′ A t U B t V , V ′ C t U−A∗ t V . By using the standard integral averaging technique and positive functionals, new oscillation and interval oscillation criteria are established for the system. These criteria extend and improve some results that have been required before. ...

PURPOSE The aims of this research were to determine the epidemiological profile of dental caries in 3- and 4-year-old preschool children living in Bogotá, Colombia, and to compare two different caries indices--the standard def and Nyvad's new caries diagnostic criteria. METHODS The children were screened by two calibrated examiners who first brushed the children's teeth and air dried them for...

with considering importance of post harvest operation on quality criteria of pot marigold (calendula offıcinalis l.), the effect of flower nutrient source (organic inputs such as cattle manure (25 t ha-1), municipal waste compost (20 t ha-1), spent mushroom compost (15 t ha-1), vermicompost (15 t ha-1) and control) as well as different drying methods including microwave (300, 600 and 900 w), ov...

background: rna interference-based gene silencing has recently been applied as an efficient tool for functional gene analysis. rorc2 is the key transcription factor orchestrating th17 cells differentiation, the cells that are known as the pathogenic elements in various autoimmune diseases. the aim of this study was to design efficient sirnas specific for rorc2 and to evaluate different criteria...

the traditional fuzzy operators, such as t-norms, t-conorms and averaging operators have been used for soil suitability evaluation to aggregate criteria as an overall suitability index. however, such operators do not account for the degree of compensation common to human aggregation criteria, especially in the presence of conflicting criteria. fuzzy integrals are powerful and flexible aggregati...

In this paper we investigate the impulsive equation { (r(t)x′) + a(t)x + f (t, x, x′) = p(t), t ≥ t0, t 6= tk, x(tk) = ckx(tk − 0), x(tk) = dkx(tk − 0), k = 1, 2, 3, . . . , and establish a couple of criteria to guarantee the equations of this type to possess the stability, including boundedness and asymptotic properties. Some examples are given to illustrate our results and the last one shows ...

The paper is concerned with robust stability criteria for Takagi- Sugeno (T-S) fuzzy systems with distributed delays and time delay in the leakage term. By exploiting a model transformation, the system is converted to one of the neutral delay system. Global robust stability result is proposed by a new Lyapunov-Krasovskii functional which takes into account the range of delay and by making use o...

We present new oscillation criteria for the differential equation of the form r t U t ′ p t k2 x t , x′ t |x t |U t q t φ x g1 t , x′ g2 t f x t 0, where U t k1 x t , x′ t |x′ t |α−1x′ t , α ≤ β, ν β − α / α 1 . Our research is different from most known ones in the sense that H function is not employed in our results, though Riccati’s substitution and its generalized forms are used. Our criteri...