Experiments have shown that unidirectional links are quite common in wireless sensor networks. Still, many MAC protocols ignore their existence, even though they have a tremendous impact on the performance of both TDMAand contention based protocols. In contention based protocols the medium may be assumed free when it is indeed busy. In TDMA based protocols two neighboring nodes might get assign...

Photonic wire lasers are a new genre of lasers that have a transverse dimension much smaller than the wavelength. Unidirectional emission is highly desirable as most of the laser power will be in the desired direction. Owing to their small lateral dimension relative to the wavelength, however, the mode mostly propagates outside the solid core. Consequently, conventional approaches to attach a h...

In periodically varying environments, population models generate periodic dynamical systems. To understand the effects of unidirectional dispersal on local patch dynamics in fluctuating environments, dynamical systems theory is used to study the resulting periodic dynamical systems. In particular, a unidirectional dispersal linked two patch nonautonomous metapopulation model is constructed and ...

We demonstrate a hybrid silicon ring laser with an internal amplifying S-bend that couples a fraction of the counter-clockwise circulating light into the the clockwise direction. The device supported single-mode, unidirectional laser oscillation at certain bias conditions. A spatial field distribution model is derived to describe the unidirectional operation. A unidirectional clockwise laser ou...

An Er"+-doped fiber ring laser with unidirectional operation without optical isolator has been investigated for different cavity conditions. The fiber ring laser cavity is built in such a way that the optical fields propagating in the two directions suffer different losses. As a consequence, the laser oscillation appears in a quasi-unidirectional form. By incorporating a fiber pigtailed bandpas...

In an attempt to simplify the technique for measuring extracellular fluid volume with sulfur-35, a weak beta-emitting radioisotope, an anthracene cell was devised with constant volume and geometry. Anthracene crystals emit a blue flourescent light when exposed to ionizing radiation. Different forms of anthra cene cells have been devised. All consist of packed anthracene crystals in a con tamer ...

The mechanism of achieving unidirectional transmission in the gratings, which only contain isotropic dielectric and metallic layers, is suggested and numerically validated. It is shown that significant transmission in one direction and nearly zero transmission in the opposite direction can be obtained in the same intrinsically isotropic gratings as those studied recently in A. E. Serebryannikov...

Isochronal maps of ventricular activation were analyzed in dogs 3-5 days after ligation of the left anterior descending coronary artery utilizing a 64-channel multiplexer. Isochronal maps of the effective refractory period were determined from 62 epicardial sites and correlated with the activation maps. The ischemia occurring in the surviving epicardial layer prolonged refractoriness in a spati...

An in vitro method is presented which measures valid, unidirectional uptake rates for lipids across the intestinal brush border. This method combines analysis by a newly devised, double isotope counting system for solubilized tissue with the use of a nonabsorbable marker to correct gross uptake determinations for contamination by adherent mucosal fluid. Of seven markers, only [(3)H]inulin measu...

This study attempts to investigate the effect of oil returns and external debt on the government expenditure in Syria over the period 1970-2010. The Johansen cointegration test showed that oil returns and external debt have a positive and significant long run relationship with government expenditure. The Granger causality test indicates unidirectional short-run causality relationships running f...