We consider a process that starts at height y, stays there for a time X0 ∼ exp(y) when it drops to a level Z1 ∼ U(0, y). Thereafter it stays at level Zn for time Xn ∼ exp(Zn), then drops to a level Zn+1 ∼ U(0, Zn). We investigate properties of this process, as well as the Poisson hyperbolic process which is obtained by randomizing the starting point y of the above process. This process is assoc...

Consider two insurance companies (or two branches of the same company) that have the same claims and they divide premia in some specified proportions. We model the occurrence of claims according to a Poisson process. The ruin is achieved if the corresponding two-dimensional risk process first leave the positive quadrant. We consider different kinds of linear barriers. We will consider two scena...

this study took an epidemiological approach toward the problem of drug addiction in tehran. the subjects were 300 addicts chosen on the basis of stratified random selection out of the population of 3627 prisoners who were all proven addicts and sentenced to imprisonment by the court in the year 1370. a descriptive survey showed that drug addiction generally, and heroin addiction specifically, i...

We propose new dependence measures for two real random variables not necessarily linearly related. Covariance and linear correlation are expressed in terms of principal components and are generalized for variables distributed along a curve. Properties of these measures are discussed. The new measures are estimated using principal curves and are computed for simulated and real data sets. Finally...

We measure the temperature, magnetic-field, and current dependence for the switching of nanomagnets by a spin-polarized current. Depending on current bias, switching can occur between either two static magnetic states or a static state and a current-driven precessional mode. In both cases, the switching is thermally activated and governed by the sample temperature, not a higher effective magnet...

In his opinion piece, Pauw [1] advocated a niche theoretical approach for studying the coexistence of plant species that differ in pollinator use, but are otherwise ecologically equivalent. By treating pollinators as a resource, one can apply the conceptual framework of the Lotka–Volterra model, which shows that coexistence can occur when each species limits its own growth rate more than that o...

Polarization properties of visible photoluminescence ~PL! from alternating hydrogenated nanocrystalline silicon-amorphous silicon multilayers excited with linearly polarized light are examined. The PL is almost linearly polarized in the direction perpendicular to the polarization of excitation light, independent of the sample orientation. The degree of linear polarization d negatively increases...

introduction: the important of comparing performance of hospitals using hospital indicators, has been made the necessary of utilizing of the application model inevitable. this study aimed to compare hospital performance key indicators simultaneity. methods: in this descriptive cross sectional and retrospective study, 31 hospitals of isfahan university of medical sciences were evaluated in 2007....