A medium access control (MAC) protocol (NULLHOC) for ad hoc networks of nodes with antenna arrays is presented. The antenna array is used for transmit and receive beamforming with the purpose of increasing spatial reuse by directing nulls at active transmitters and receivers in the neighborhood. In contrast to previous work with directional antennas, our approach is applicable to multipath chan...

This letter derives the capacity region of asynchronous multiple access channel (MAC) with faster-than-Nyquist (FTN) signaling. We first express in frequency domain. Next, we prove that definition for finite memory MAC can be generalized to infinite MAC. The achievable rate utilizing fact achieves same calculated Our analysis shows power optimization is necessary achieve and FTN.

BACKGROUND The cholinergic arousal systems are known to critically regulate the state of consciousness. The aim of this study was to determine the effect of isoflurane on the inhibitory or excitatory neurotransmitters efflux in important nuclei within the cholinergic arousal system using in vivo intracerebral microdialysis. METHODS The efflux of glutamate, gamma-aminobutyric acid (GABA), or a...

PURPOSE Test-retest variability (TRV) limits our ability to detect clinically significant changes in visual acuity (VA). We wanted to compare the effect of scoring and termination rules on TRV for logMAR charts, employing either conventional or pseudo high-pass (Vanishing Optotype) letters. METHODS VA measurements and TRV were compared in 50 uncorrected normal observers (17 male, mean age 42....

Because the sensors of wireless body area networks (WBANs) have limited battery power, many studies have focused on energy efficient medium access control (MAC) protocols to extend the lifetime of the sensors. In addition, WBANs face energy-exhausting attacks, which force the sensors to consume battery power partially or thoroughly. These attacks occur mainly in the MAC layer and threaten sever...

W D M rings are receiving significant attention in the field of all-optical networks because their implementation appears to be feasible with state-of-the-art components. Several MAC protocols were recently proposed in order to resolve contentions among nodes sharing the available wavelengths an W D M rings. These MAC protocols achieve high e&ciency but unsatisfactory fairness, due to the asymm...

BACKGROUND Airway eosinophilia is considered a central event in the pathogenesis of asthma. The toxic components of eosinophils are thought to be important in inducing bronchial mucosal injury and dysfunction. Previous studies have suggested an interaction between nitric oxide (NO) and chemokines in modulating eosinophil functions, but this is still conflicting. In the present study, we have ca...

BACKGROUND In this study we aimed to clarify the role of endothelin in arterial pressure regulation during anaesthesia with increasing concentrations of sevoflurane (1-3 MAC) and compare it with those of vasopressin and angiotensin. METHODS After an awake control period, on different days, six dogs underwent each of the following four interventions: sevoflurane anaesthesia alone (1-3 MAC), se...