`Minting' electronic cash

Electronic equivalents of traditional cash payment systems are being launched worldwide. Electronic cash can combine the benefits of traditional cash with those of payment by debit and credit card, while circumventing both their shortcomings. As with traditional cash, electronic cash should have high acceptability and be suitable for low value payment from person to person. With the possible exception of online payment platforms such as the Internet, it is preferred that payments be verifiable offline, without the bank's involvement, for reasons of cost effectiveness and speed. To facilitate electronic cash payments over the phone and the Internet, physical proximity of payer and payee should not be necessary. Moreover, electronic cash should offer privacy of payments. In particular, payments by an honest payer should be untraceable, and information about transaction content should remain privy to payer and payee. Yet a payer ought to always be able to trace the payee; traceability suits electronic cash and is as open to extortion, money laundering, and bribery as a check or wire transfer. Lastly, as with payments by debit and credit card, electronic cash should be convenient to store and transport, while protecting users against loss, theft, and accidental destruction     

Wavelength selection for low-saturation pulse oximetry

Conventional pulse oximeters are accurate at high oxygen saturation under a variety of physiological conditions but show worsening accuracy at lower saturation (below 70%). Numerical modeling suggests that sensors fabricated with 735 and 890 nm emitters should read more accurately at low saturation under a variety of conditions than sensors made with conventionally used 660 and 900 nm band emitters. Recent animal testing confirms this expectation. It is postulated that the most repeatable and stable accuracy of the pulse oximeter occurs when the fractional change in photon path lengths due to perturbations in the tissue (relative to the conditions present during system calibration) is equivalent at the two wavelengths. Additionally, the penetration depth (and/or breadth) of the probing light needs to be well matched at the two wavelengths in order to minimize the effects of tissue heterogeneity. At high saturation these conditions are optimally met with 660 and 900 nm band emitters, while at low saturation 735 and 890 nm provide better performance     

Thick-layer glycerin-containing bichromated gelatin for recording volume holograms

A thick-layer light-sensitive material consisting of glycerin-containing bichromated gelatin has been prepared and used to record real-time volume holograms with 0.44 μm helium-cadmium laser radiation. The thickness of the layers is 400–600 μm. The holographic sensitivity of the material is 1 J/cm². The highest diffraction efficiency of holograms recorded using a symmetric system with parallel beams is 32%. Pis’ma Zh. Tekh. Fiz. 23, 62–65 (April 12, 1997)     

Propagation characteristics of a heaviside absorbing layer for TLM

The perfectly matched layer for use with the finite-difference time-domain method is adapted to our transmission-line matrix simulation as what we call a heaviside absorbing layer (HAL). It is shown that the reflection coefficient for the wave incident on a HAL is less than that of the wave incident on a matched-load termination at all angles of incidence. Furthermore, the dispersion relation of a transmission-line matrix mesh of a symmetrical condensed node with both electric and magnetic loss stubs is derived. It provides guidance on how to choose the losses of HAL and other simulation parameters properly     

Analysis of switched diversity TCM-MPSK systems on Nakagami fadingchannels

Space diversity reception and forward-error correction coding are powerful techniques to combat multipath fading encountered in mobile radio communications. In this paper, we analyze the performance of a discrete-time switched diversity system using trellis-coded modulation multiple phase-shift keying (TCM-MPSK) on slow, nonselective correlated Nakagami (1960) fading channels. Analytical upper bounds using the transfer function bounding technique are obtained and illustrated by several numerical examples. A simple integral expression for calculating the exact pairwise error probability is presented. The use of optimum adaptive and fixed switching thresholds is considered. Monte Carlo simulation results, which are more indicative of the exact system performance, are also given     

Use of a two-wire microwave line at the boundary of the investigated zone to measure the electron density in a low-temperature plasma

A new method based on a two-wire line has been developed for noncontact diagnostics of a low-temperature plasma and its fluxes in channels with complex profiles. This method provides good spatial and time resolution. Pis’ma Zh. Tekh. Fiz. 23, 1–7 (July 26, 1997)     

Perineurioma: an unusual cause of an external auditory canal polyp

BACKGROUND: Home parenteral nutrition (HPN) is used to treat intestinal failure. A minority of HPN patients are dependent on opiates and benzodiazepines to control pain and anxiety. The aim of this study was to determine what effects such drug dependence had on patient outcomes. METHODS: Ten dependent patients were prospectively compared with 10 well-matched, nondependent HPN patients for the same 12-month period. Episodes of line sepsis and other complications were documented and the cost of treatment estimated. Health status was measured using the SF36 and EuroQol instruments. RESULTS: The dependent group had significantly more episodes of central line sepsis (p = .0007) as well as other complications (p = .0002). This led to significantly longer periods of inpatient care (p = .0004) and therefore higher costs of treatment. Health status was lower in the dependent group; they reported more pain (p = .04) and less energy (p = .04). CONCLUSIONS: The complication rate and increased cost of treatment for opiate- and sedative-dependent patients receiving HPN significantly detract from the overall outcome of this therapy.     

Estimating local mean signal strength of indoor multipathpropagation

We explore techniques for the measurement of local mean signal strength at 900 MHz and 2 GHz. In particular, we characterize the impact of transmitter and receiver antenna rotation on the estimated local mean. Then, we explore the collection of high resolution data while moving along a linear trajectory and using linear averaging techniques to estimate the local mean. With this information, the best measurement techniques can be chosen depending on the required speed versus accuracy tradeoff. Finally, we use a ray tracing propagation model to evaluate different methods of calculating the local mean signal strength for indoor environments