New bounds for the Marcum Q-function

New bounds are proposed for the Marcum Q-function, which is defined by an integral expression where the 0th-order modified Bessel function appears. The proposed bounds are derived by suitable approximations of the 0th-order modified Bessel function in the integration region of the Marcum Q-function. They prove to be very tight and outperform bounds previously proposed in the literature. In particular, the proposed bounds are noticeably good for large values of the parameters of the Marcum Q-function, where previously introduced bounds fail and where exact computation of the function becomes critical due to numerical problems     

Experimental determination of thermal conductivity of apple and potato at different moisture contents

Thermal conductivity of apple and potato samples was measured by means of a specifically designed apparatus based on Fitch's method. The thermal conductivity was determined at various moisture contents at the sample mean temperature of 30 °C. As expected the conductivity decreases with the decrease in moisture content. Thermal conductivity data were correlated with moisture content using a straight line.     

Comparative Rheomechanical and Adhesive Properties of Two Hydrocolloid Dressings: Dependence on the Degree of Hydration

Hydration is believed to modify the mechanical properties (resistance to stress) and the rheological (viscoelastic) properties of hydrocolloid dressings. Rheomechanical properties in turn influence adhesional properties. In this work the relationships between the degree of hydration and the rheomechanical and the adhesive properties of two different commercial dressings (regular and nondispersive) were investigated. The two dressings showed different hydration characteristics. The regular dressing takes up water rapidly and tends to reach saturation after 12 hr. As the dressing swells and loses its integrity there is an accompanying reduction of both rheomechanical and adhesive properties. The nondispersive dressing exhibits a linear water uptake profile over extended periods of hydration up to 4 days. It does not swell and its rheomechanical and adhesive properties remain unchanged after hydration, The comparative evaluation of the results obtained with the various methods points to the relevance of mechanical and viscoelastic properties to the functionality assessment of dressings.     

Helicobacter pylori at Hospital Santo Tomás

We studied the incidence of infection with Helicobacter pylori in Panamanians with chronic dyspepsia, gastric or duodenal ulcer, gastritis or gastric cancer. The histopathology was positive in 54 (81%) of 66 patients; the urea test was positive in 52 (82.5%) of 63 cases; the impromptu was positive in 51 (79.6) of 64 patients; the endoscopic examination was positive in 64 (82.9%) of 77 examinations.     

Subkilohertz fluctuations and mode hopping in high-powergrating-stabilized 980-nm pumps

The behavior of fiber Bragg grating (FBG)-stabilized 980-nm pump lasers is experimentally and theoretically investigated. The subkilohertz noise in the emitted power is related to the coexistence and oscillation between coherence collapsed state and narrow linewidth single-mode (SM) operation. These findings are theoretically discussed by using a multimode time-domain model that accounts for spatial harmonics and includes nonlinear gain. One additional result is an indication that kinks in the L-I curve can be explained by nonlinear mode competition     

Contactless system for dynamic characterisation of microresonators

A cost-effective system for the contactless characterisation of microresonators vibrating in out-of-plane mode is presented. The system provides swept-frequency excitation to the microresonator, detects the mechanical vibrations by a single-point triangulator made by a laser diode and a four-quadrant detector, and exploits synchronous undersampling of the readout signal to derive the frequency response of the microresonator. The system has been prototyped and tested using a piezoelectric bimorph cantilever as the resonator. A displacement resolution of around 100 nm has been obtained in the frequency range of up to some tens of kilohertz.     

On the non-blocking conditions of self-routeing multistage interconnection networks

This paper studies the non-blocking conditions of a generic N × N multistage interconnection network, such as an omega network or an n-cube network, in which only one path connects any inlet to each outlet and different I/O paths can share interstage links. It is widely known that any of these networks is non-blocking for a compact and monotone pattern of k ≤ N I/O paths. Recently it has become very important to show the network non-blocking property for permutation sets, wider than the compact and monotone, which are usually encountered in broadband ATM networks. By using a new approach based on the concept of distance between I/O paths, we show here that these networks are non-blocking for a set of I/O paths obtained by shifting cyclically the inlets of a compact and monotone pattern of I/O paths by an arbitrary number of steps.