Some algorithms for the solution of handed Toeplitz sys-tems calculate certain elements of the solution first and then the re-maining elements by forward or backward substitution. We show that,for symmetric matrices, this method is almost always highly unstable.A numerical example is given to support the argument.

The two-dimensional striation model consists of a nonlinear system of PDE’s which arises in the modeling of the ionospheric plasma. The local-in-time existence of strong solutions is first proved using Banach’s fixed point theorem. Then, under physically relevant assumptions, the system is shown to be nonlinearly unstable as soon as it is linearly unstable. Moreover, the instability occurs befo...

The hypocalcemic activity("calcium activity"; Ito, 1960)of parotin was reported to be more unstable in acid aqueous solution than in alkaline solution, and its activity decreased when incubated in phosphate buffer of pH 7.6 at 40•Ž for 1 hr.(Ito and Mizutani, 1952b). The present experiments were undertaken to study the effect of heat, acid, and alkaline treatments on the biological as well as p...

We consider a ring of identical neurons with delayed nearest neighborhood inhibitory interaction. Under general conditions, such a network has a slowly oscillatory synchronous periodic solution which is completely characterized by a scalar delay differential equation with negative feedback. Despite the fact that the slowly oscillatory periodic solution of the scalar equation is stable, we show ...

An analytical solution is provided to the problem of minimising a convex quadratic under a general quadratic (inequality) constraint, additional affine constraints being easily accommodated. Such problems occur widely. The explicit, analytical solution provided offers insight into the diverse nature both of special cases of this problem and of their solution sets. This sheds light on algorithm ...

Aloe vera gel is widely used as a functional ingredient in food processing. This gel is very unstable due to its high water activity. Drying process can be used to obtain shelf stable products. Response surface methodology was used to assess the effects of solution concentration (30-60% w/w), solution temperature (30-50°C) and immersion time (4-6h) at atmospheric pressure and constant solution ...

unstable angina has progressive process and even in rest time, it happens frequently. it is a serious situation and 15-20 percent of patients are dying in duration of one year. treatment: patients often hospitalized because observation of their reactions to treatment is easier in hospital. treatment plan must be explain for them carefully. when patient’s situation due to anxiety is critical, be...

Using the methods developed for different Bianchi class A cosmological models we treat the simplest Bianchi class B model, namely Bianchi type V. The future non-linear stability for solutions of the Einstein-Vlasov system is demonstrated and it is shown that these solutions are asymptotically stable to the Milne solution. Within the isotropic solutions of the Einstein-Vlasov system the spatiall...

recent reports have suggested that cytomegalovirus (cmv) infection may contribute to risk of cardiovascular disease. however, relationship between cmv infection and unstable angina (ua) is controversial and studies about this subject in iran and even region are lacking. the aim of this study was to determine whether unstable angina is related to seropositivity to chronic cytomegalovirus infecti...