User mobility in wireless data networks is increasing because of technological advances and the desire for voice and multimedia applications. These applications, however, require fast handoffs between base stations to maintain the quality of the connections. In this paper, the authors describe the use of novel and efficient data structure which dynamically allocates guard channel for handoffs a...

Dropping probability of handoff calls and blocking probability of new calls are two important QoS measures for cellular networks. Call admission policies, such as fractional guard channel and uniform fractional guard channel policies are used to maintain the pre-specified level of QoS. Since the parameters of network traffics are unknown and time varying, the optimal number of guard channels is...

In response to drought stress, the phytohormone abscisic acid (ABA) induces stomatal closure. Thereby the stress hormone activates guard cell anion channels in a calcium-dependent, as well as -independent, manner. Open stomata 1 protein kinase (OST1) and ABI1 protein phosphatase (ABA insensitive 1) represent key components of calcium-independent ABA signaling. Recently, the guard cell anion cha...

Guard cells are a valuable model system for the study of photoreception, ion transport, and osmoregulation in plant cells. Changes in stomatal apertures occur when sensing mechanisms within the guard cells transduce environmental stimull into the ion fluxes and biosynthesis of organic solutes that regulate turgor. The electrical events mediating sensory transduction in guard cells can be charac...

The known channel allocation schemes in Personal Communications Service (PCS) operating with fixed guard channels for handoff calls can lead to fail in utilizing the limited channels such a wasting or lacking the number of guard channels, since the handof traflcs which depend on mobility of users are always not stationary. In this paper, we use F u z y Logic Controller (FLC) to generate proper ...

Hando is an important issue in mobile communication systems. However, most previous studies were based on TDMA systems considering voice and data tra c with the same bit rate. Hando management for high rate tra c is required in multi-media CDMA systems. Hando management scheme for high rate tra c is proposed by using guard channels and Reservation-on-Demand queue control. The effects of the num...

In the present paper, we develop an adaptive algorithm for call admission control in wireless networks. The algorithm is built upon the concept of guard channels and it uses an adaptation algorithm to search automatically the optimal number of guard channels to be reserved at each base station. The quality of service parameters used in our study are the new call blocking probability and the han...

Inward-rectifying K+ channels serve as a major pathway for Ca2+-sensitive K+ influx into guard cells. Arabidopsis thaliana guard cell inward-rectifying K+ channels are assembled from multiple K+ channel subunits. Following the recent isolation and characterization of an akt2/3-1 knockout mutant, we examined whether the AKT2/3 subunit carries the Ca2+ sensitivity of the guard cell inward rectifi...

Methyl jasmonate (MeJA) elicits stomatal closing similar to abscisic acid (ABA), but whether the two compounds use similar or different signaling mechanisms in guard cells remains to be clarified. We investigated the effects of MeJA and ABA on second messenger production and ion channel activation in guard cells of wild-type Arabidopsis (Arabidopsis thaliana) and MeJA-insensitive coronatine-ins...

Guard cells form stomatal pores that optimize photosynthetic carbon dioxide uptake with minimal water loss. Stomatal movements are controlled by complex signaling networks that respond to environmental and endogenous signals. Regulation of stomatal aperture requires coordinated activity of reactive oxygen species (ROS)-generating enzymes, signaling proteins, and downstream executors such as ion...