Effect of a hands-free wire on specific absorption rate for a waist-mounted 1.8 GHz cellular telephone handset.

A common feature of cellular telephony is the use of a 'hands-free' audio extension lead connected to a waist-worn handset. Interaction between the transmitting antenna, the wire and the user's body can occur, with detrimental effects including polar pattern degradation, reduced efficiency and localized increases in specific absorption rate (SAR). Using a realistic full-body model of an adult male, finite difference time domain analysis was employed to investigate the coupling between a hip-mounted 1.8 GHz handset fitted with a monopole antenna and a 1 m long wire representing a hands-free wire. Conduction current densities were computed for three identifiable coupling modes: magnetic-only, conductive-only and combined conductive-and-magnetic. Magnetic-only coupling was dominant. Without the lead, placing the handset at waist height led to a 42.8% increase in the total energy deposited in the body, compared to use at the head. Introducing the lead further increased the body loss, with a reduction in system radiation efficiency from 52% to 43.7%. Without the hands-free lead, the peak 1 g and 10 g SARs were 0.450 W kg(-1) and 0.265 W kg(-1), respectively, for 125 mW transmit power. With the hands-free lead connected, these values increased to 1.14 W kg(-1) and 0.430 W kg(-1), respectively.

Radiowave propagation from a tissue-implanted source at 418 MHz and 916.5 MHz.

Tissue-implanted ultra-high frequency (UHF) radio devices are being employed in both humans and animals for telemetry and telecommand applications. This paper describes the experimental measurement and electromagnetic modeling of propagation from 418-MHz and 916.5-MHz sources placed in the human vagina. Whole-body homogeneous and semi-segmented software models were constructed using data from the Visible Human Project. Bodyworn radiation efficiencies for a vaginally placed 418-MHz source were calculated using finite-difference time-domain and ranged between 1.6% and 3.4% (corresponding to net body losses of between 14.7 and 18.0 dB). Greater losses were encountered at 916.5 MHz, with efficiencies between 0.36% and 0.46% (net body loss ranging between 23.4 and 24.4 dB). Practical measurements were in good agreement with simulations, to within 2 dB at 418 MHz and 3 dB at 916.5 MHz. The degree of tissue-segmentation for whole-body models was found to have a minimal effect on calculated azimuthal radiation patterns and bodyworn radiation efficiency, provided the region surrounding the implanted source was sufficiently detailed.

The design and performance of a 2.5-GHz telecommand link for wireless biomedical monitoring.

This paper details the implementation and operational performance of a minimum-power 2.45-GHz pulse receiver and a companion on-off keyed transmitter for use in a semi-active, duplex RF biomedical transponder. A 50-ohm microstrip stub-matched zero-bias diode detector forms the heart of a body-worn receiver that has a (CMOS baseband amplifier consuming 20 microA from +3 V and achieves a tangential sensitivity of -53 dBm. The base transmitter generates 0.5 W of peak RF output power into 50 ohms. Both linear and right-hand circularly polarized Tx-Rx antenna sets were employed in system reliability trials carried out in a hospital Coronary Care Unit. For transmitting antenna heights between 0.3 and 2.2 m above floor level, transponder interrogations were 95% reliable within the 67-m2 area of the ward, falling to an average of 46% in the surrounding rooms and corridors. Overall, the circular antenna set gave the higher reliability and lower propagation power decay index.

FDTD analysis of close-coupled 418 MHz radiating devices for human biotelemetry.

This paper describes the finite-difference time-domain (FDTD) analysis of antenna-body interaction effects occurring when chest-mounted 418 MHz radio transmitters are used for medical telemetry applications. Whole-body software models (homogeneous, layered and tissue-segmented) were developed for an adult male subject. Using an electrically small (300 mm2) planar loop antenna, calculated radiation efficiencies ranged between 33.5% and 39.2% for a whole-body model, and between 60.7% and 66.1% for a torso; radiation patterns were found to be largely independent of model composition. The computed radiation efficiency for a 21.5 kg phantom representing a six-year-old female was within 1.1 dB of measured results (actual body mass 28 kg) and well-correlated azimuthal radiation patterns were noted.

RF performance of a 418-MHz radio telemeter packaged for human vaginal placement.

The electrical and communication performance of a 0.8-microW UHF temperature telemeter designed for human vaginal placement is discussed; a solenoidal loop antenna was used, occupying a volume of 0.1 cm3. In situ, measured power absorption was between 19-25 dB, resulting in an effective operating range of 10 m. Capacitive loading lowered the antenna's resonant frequency by 1.4% and there was a significant polarization change in the radiated output.

The effect of a reduced energy diet and meal patterns on smoking and coffee drinking in women.

OBJECTIVE: We examined the effect of three feeding conditions on cigarette smoking and coffee drinking in four healthy women. We hypothesized that food deprivation and changes in meal patterns would increase rates of smoking and coffee drinking based on extensive animal literature documenting this effect. METHOD: The conditions were: normal three meals per day containing usual energy intake, one meal per day (dinner time) containing 50% of usual energy intake, and three meals per day containing 50% of usual energy intake. Each condition lasted 3 days. RESULTS: Neither reduction of energy intake nor alteration in the pattern of meals had any observable effect on number of cigarettes smoked, number of cups of coffee consumed, expired air carbon monoxide levels, or urges to smoke or drink coffee. DISCUSSION: This study adds to the growing body of literature suggesting that the food deprivation effect observed in animals does not apply readily to humans. Reasons for the absence of this effect are discussed.

Vaginal temperature sensing using UHF radio telemetry.

User-induced errors are common when women repetitively employ conventional probe type thermometers to chart their basal body temperatures in an effort to indicate ovulation. An alternative technique employing a two-part telemetric thermometer is proposed, with low-power, SAWR-controlled UHF radio as the transmission medium. Worn overnight in the vagina, the 1 microW erp telemetry transmitter sends pulse modulated data continuously to a microcontroller in a nearby receiver; a real time clock enables programmable sampling and storage of the subject's temperature to 0.1 degrees C resolution. Initial clinical results indicate an enhanced performance compared to oral and axillary temperature trends taken by a mercury-in-glass thermometer. Polar plots of both the isolated and body-worn telemetry transmitter are presented; body induced attenuations of up to 30 dB were measured.

Low-power radio telemetry: the potential for remote patient monitoring.

Radio-based signalling devices will play an important role in future generations of remote patient monitoring equipment, both at home and in hospital. Ultimately, it will be possible to sample vital signs from patients, whatever their location and without them necessarily being aware that a measurement is being taken. This paper reviews current methods for the transmission by radio of physiological parameters over ranges of 0.3, 3 and 30 m, and describes the radiofrequency hardware required and the carrier frequencies commonly used. Future developments, including full duplex systems and the use of more advanced modulation schemes, are described. The paper concludes with a case study of a human temperature telemeter built to indicate ovulation. Clinical results clearly show the advantage to be had in adopting radio biotelemetry in this instance.

Helping oneself by helping others: evaluation of a service credit banking demonstration.

Between 1987 and 1990, the Robert Wood Johnson Foundation funded six service credit banking demonstration programs among the elderly in which participants delivered services in return for credits, entitling them to later service. This evaluation of the demonstrations found that these six sites successfully attracted elders for the delivery of household support services to a relatively old, frail population with potentially limited social networks. Evidence on the significance of the "credit" in attracting volunteers was mixed, but the programs have attracted new volunteers, and have not substituted for other volunteer activities. Program development has entailed considerable staff investment in volunteer support; programs are better understood as community membership organizations than as mechanical exchanges.

Working group recommendations: measuring outcomes of care in geriatric evaluation and management units.

Issues related to measuring outcomes of care in geriatric evaluation and management (GEM) units were identified by the outcomes working group of the GEM evaluation conference. GEM units have as a major goal the improvement or maintenance of both physical and psychosocial function. Suggested outcome measures for physical health included survival, restricted activity days, general health perceptions, comprehensive physical function, and miscellaneous specific types of functioning. In the area of psycho-social function, the working group suggested measuring cognitive function, affect/life satisfaction, social function, and satisfaction with care. The patient's caregiver (eg, spouse or child) is often an important target of GEM care, and the group suggested measuring caregiver burden, life satisfaction, and assessment of patient behavior problems. While the primary goal of GEM units is to improve health status, their effects on the utilization and cost of health care are important to decisions about wide-spread implementation and funding. The group therefore suggested a comprehensive assessment of these outcomes. Among the large array of recommended outcomes, the most important were thought to be mortality, function, and cost.

Case-mix payment for nursing home care: lessons from Maryland.

Even before Medicare adopted case-based payments for hospitals, some state Medicaid programs employed case-mix payment systems for nursing home care. Their purpose was less to promote cost containment than to improve access to nursing homes for the most costly patients. This paper evaluates one such system, adopted by the state of Maryland in 1983 as part of an overall reimbursement reform. Using data on nursing home patient characteristics, costs, and staffing, as well as interviews with officials and various providers of care, the article shows that Maryland's system was successful in shifting nursing home service away from light-care and toward heavy-care patients. Furthermore, the shift occurred without inducing readily measurable declines in quality of care and with little additional administrative cost (partly because the state built its case-mix system on preexisting patient review activities). Although states could learn from and improve upon Maryland's experience--most notably in offering incentives to improve quality of care and in targeting community care on the light-care patients that nursing homes become less willing to serve--Maryland demonstrates that case-mix payment can change nursing home behavior in desired directions without substantial negative consequences.

A perspective on long-term care for the elderly.

Long-term care represents a significant burden to the approximately 7 million elderly in need, their families, and the Medicaid program. Concerns exist about access, quality, cost, and the distribution of the burden of care. In this article each area is discussed, highlighting the principal issues, identifying the unique aspects that pertain to long-term care, and exploring the implications for research and policy development. Future trends, especially the growth of the elderly population, are expected to affect significantly the provision of long-term care. The considerable uncertainty about how these trends may impact on long-term care is described, and the critical role social choice will play in shaping the future long-term care system is emphasized.

Chronic mental patients in nursing homes: reexamining data from the National Nursing Home Survey.

A reanalysis of data from the 1977 National Nursing Home Survey, including data not available earlier, led to an estimate that 668,000 chronic mentally ill patients reside in nursing homes. Several subpopulations of nursing home residents were also identified and compared, which showed, for instance, that residents with only mental disorders were younger, were less likely to need the help of another person in daily activities, and were much less likely to be totally dependent than residents with only physical disorders. However, not surprisingly, mentally ill residents were more likely to have behavior problems and to have much longer stays. Residents diagnosed as senile, with or without a physical disorder, more closely resembled the purely physically ill than the purely mentally ill patients. The data illustrate the wide range of needs of mentally ill nursing home residents and reinforce the importance of assessing and improving the appropriateness of care offered.

Determinants of nursing home discharge status.

Data from the 1977 National Nursing Home Survey show that more than one fourth of admissions are discharged back to the community. Weighted logistical regression analysis was used to assess the impacts of patient, facility, and contextual characteristics on discharge status. The important exception is the proportion of the home's patients supported publicly, especially by Medicaid. Patients in homes that are heavily Medicaid supported have a significantly reduced chance of community discharge. Profit versus nonprofit status of the facility does not prove to be significant, nor does chain membership. Important patient characteristics are marital status, age, diagnosis, physical dependency, mental disorders, and source of payment for charges. Climate is significant, while occupancy rate is not.

Care for the chronically ill: nursing home incentive payment experience.

Nursing home reimbursement systems which do not adjust payment levels to patient care needs lead to access problems for heavy-care patients. Unnecessarily long and costly hospital stays may result. A patient-based nursing home incentive reimbursement system has been designed and is being evaluated in a controlled field experiment in 36 California skilled nursing facilities. Incentives are paid for admitting heavy-care patients, meeting outcome goals on some patients, and discharging and maintaining some patients in the community. This article describes a nursing home reimbursement system which is intended to simultaneously mitigate problems of restricted access, inefficient use of beds, and nonoptimal care. It also discusses the approach to evaluating this broad social intervention by application of a controlled experimental design.