In estimating the channel holding time distribution in cellular telephone systems, the pdf of the fraction of two non-negative random variables, distance and speed, has to be determined. Instead of the repeated application of numerical integration we show that the pdf of the holding time is the solution of an initial value problem of a non-linear ordinary diierential equation, which can be solv...

The performance degradation as a result of acoustical environment mismatch remains an important practical problem in speech recognition. The problem carries a greater significance in applications over telecommunication channels, especially with the wider use of personal communications systems such as cellular phones which invariably present challenging acoustical conditions. In this work, we in...

CONTEXT A relative paucity of data exist on the possible health effects of using cellular telephones. OBJECTIVE To test the hypothesis that using handheld cellular telephones is related to the risk of primary brain cancer. DESIGN AND SETTING Case-control study conducted in 5 US academic medical centers between 1994 and 1998 using a structured questionnaire. PATIENTS A total of 469 men and...

Despite limited evidence, cellular telephones have been claimed to cause cancer, especially in the brain. In this Danish study, the authors examined the possible association between use of cellular telephones and development of acoustic neuroma. Between 2000 and 2002, they ascertained 106 incident cases and matched these persons with 212 randomly sampled, population-based controls on age and se...

RE: " CELLULAR TELEPHONE USE AND RISK OF ACOUSTIC NEUROMA " Christensen et al. (1) recently presented results on the use of cellular telephones and the risk for acoustic neuroma. However, in our opinion, several issues need to be clarified in the paper. Our main concern is that the study did not take into account exposures from cordless phones, and associations specific for ever use of analog o...

Radiofrequency (RF) waves have long been used for different types of information exchange via the air waves--wireless Morse code, radio, television, and wireless telephone (i.e., construction and operation of telephones or telephone systems). Increasingly larger numbers of people rely on mobile telephone technology, and health concerns about the associated RF exposure have been raised, particul...

BACKGROUND In a general practice in The Netherlands, the demand for direct telephone consultation with the doctor became extreme, which resulted in poorly managed consultations, and poor telephone access due to busy lines. A call-back telephone appointment system was therefore introduced: all calls are answered and, when possible, managed by the practice assistant. If the assistant feels incapa...

This invited lecture was presented at the Extension Division of the University of W isconsin at a time when cellular telephone (hence the somewhat obsolete wording of the title) had not yet reached its wide acceptance, but system designers were rightfully concerned with surge protection of that emerging technology. One particular aspect of a cell phone relay tower is that it is often installed ...

High assurance computer systems are computer systems where convincing evidence is required that the system satis es a collection of critical properties. To operate correctly, these systems must satisfy properties such as safety and security. Examples of high assurance systems include ight control systems, medical systems, and control systems for nuclear plants. In addition, increased reliance o...