this is the first report about adverse inhibitory effect of v-guard and e-guard gasoline additives against soil beneficial streptomyces. v-guard and e-guard gasoline additives are anti valve seat recession agents used in unleaded gas for old car engines in iran. they contaminate soil and groundwater by fuel leaks and spills. streptomyces are of the major contributors to the biological buffering...

Guard cell turgor responds to the osmogradient across the plasma membrane and controls the stomatal aperture. Here, we report that guard cells utilize voltage-dependent K+ channels as targets of the osmosensing pathway, providing a positive feedback mechanism for stomatal regulation. When exposed to a hypotonic condition, the inward K+ current (IKin) was highly activated, whereas the outward K+...

This paper presents a fast low-complexity synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems over fading channels. By utilizing the guard interval in OFDM signals, the frame synchronization and the frequency offset estimation are considered simultaneously. The implementation can be simplified by only using the sign bits of the in-phase and the quadrature compon...

We develop a new linear space-time precoding scheme for OFDM systems based on channel state information at the transmitter. The filter is derived for frequency-selective MISO as well as for SISO channels using a minimum mean square error criterion with a constraint on transmit power. The guard interval of the resulting transmitted signal is no longer cyclic extension. Drawbacks of OFDM systems ...

(1) Soft Computing Laboratory, Computer Engineering Department, Amirkabir University of Technology, Tehran, Iran, In this paper, we consider the call admission problem in next generation wireless networks, which must handles multi-media traffics. We give an algorithm, which finds the optimal number of guard channels, which minimizes the overall blocking probability calls with lowest level of Qo...

Stomatal guard cells are unique as a plant cell model and, because of the depth of knowledge now to hand on ion transport and its regulation, serve as an excellent model for the analysis of stimulus-response coupling in higher plants. Parallel controls - mediated by Ca(2+), H(+) protein kinases and phosphatases - regulate the gating of the K(+) and Cl(-) channels that facilitate solute flux for...

Efficient channel allocation is important for meeting the quality of service (QoS) requirements of both GSM voice calls and GPRS packets in integrated GSM/GPRS networks. In this paper, we propose a new dynamic channel allocation scheme with guard channel, channel deallocation/re-allocation for voice call and packet queue for GSM/GPRS networks. An analytic model with general GPRS channel require...

In a LEO system, a user’s call may be handed over constantly from one satellite to another due to visibility changes caused by satellites’ movements. The resultant system performance will degrade if handover calls occur frequently but few are transferred successfully. This paper considered a multiservice LEO system that allows different bandwidth/channel allocations (so-called multirate) on-dem...