In this paper, we consider the call admission problem in cellular network with two classes of voice users. In the first part of paper, we introduce a two-threshold guard channel policy and study its limiting behavior under the stationary traffic. Then we give an algorithm for finding the optimal number of guard channels. In the second part of this paper, we give an algorithm, which minimizes th...

Guard channels improve the probability of successful handoffs by reserving a number of channels exclusively for handoffs. This concept has the risk of underutilization of radio spectrum due to the fact that fewer channels are granted to originating calls even if these guard channels are not always used, when originating calls are starving for the want of channels. The penalty is the reduction o...

Drought induces stomatal closure, a response that is associated with the activation of plasma membrane anion channels in guard cells, by the phytohormone abscisic acid (ABA). In several species, this response is associated with changes in the cytoplasmic free Ca concentration. In Vicia faba, however, guard cell anion channels activate in a Ca-independent manner. Because of potential differences...

Drought induces stomatal closure, a response that is associated with the activation of plasma membrane anion channels in guard cells, by the phytohormone abscisic acid (ABA). In several species, this response is associated with changes in the cytoplasmic free Ca(2+) concentration. In Vicia faba, however, guard cell anion channels activate in a Ca(2+)-independent manner. Because of potential dif...

Slow anion channels in the plasma membrane of guard cells have been suggested to constitute an important control mechanism for long-term ion efflux, which produces stomatal closing. ldentification of pharmacological blockers of these slow anion channels is instrumental for understanding plant anion channel function and structure. Patch clamp studies were performed on guard cell protoplasts to i...

In responses to a number of environmental stimuli, changes of cytoplasmic [Ca(2+)](cyt) in stomatal guard cells play important roles in regulation of stomatal movements. In this study, the osmo-sensitive and stretch-activated (SA) Ca(2+) channels in the plasma membrane of Vicia faba guard cells are identified, and their regulation by osmotic changes and actin dynamics are characterized. The ide...

Inward-rectifying K+ (K+in) channels in the guard cell plasma membrane have been suggested to function as a major pathway for K+ influx into guard cells during stomatal opening. When K+in channels were blocked with external Cs+ in wild-type Arabidopsis guard cells, light-induced stomatal opening was reduced. Transgenic Arabidopsis plants were generated that expressed a mutant of the guard cell ...

Inward-rectifying K+ (K+in) channels in the guard cell plasma membrane have been suggested to function as a major pathway for K+ influx into guard cells during stomatal opening. When K+, channels were blocked with external Cs+ in wild-type Arabidopsis guard cells, light-induced stomatal opening was reduced. Transgenic Arabidopsis plants were generated that expressed a mutant of the guard cell K...

Stomatal guard cells control CO(2) uptake and water loss between plants and the atmosphere. Stomatal closure in response to the drought stress hormone, abscisic acid (ABA), results from anion and K(+) release from guard cells. Previous studies have shown that cytosolic Ca(2+) elevation and ABA activate S-type anion channels in the plasma membrane of guard cells, leading to stomatal closure. How...

Inward-rectifying potassium (K+(in)) channels in guard cells have been suggested to provide a pathway for K+ uptake into guard cells during stomatal opening. To test the proposed role of guard cell K+(in) channels in light-induced stomatal opening, transgenic Arabidopsis plants were generated that expressed dominant negative point mutations in the K+(in) channel subunit KAT1. Patch-clamp analys...