Portable through-metal ultrasonic power transfer using a dry-coupled detachable transmitter.

Ultrasonic waves can be used to transfer power and data efficiently through metallic enclosures when feedthroughs are not practical due to structural or electromagnetic shielding considerations. Previous implementations of ultrasonic power transfer (UPT) used a piezoelectric transducer permanently bonded to the metal for efficient ultrasonic coupling. For portable operation, it is essential to have a detachable transmitter (charger) that is only attached to the enclosure while transferring power. This requirement presents several design challenges; notably, detachable ultrasonic coupling typically relies on liquid or gel couplant, which may become inconvenient or less robust during repeated attachment and detachment. Thus, this work develops a dry-coupled detachable UPT system to transfer power efficiently through a metallic enclosure without the need for a liquid couplant. Low attenuation soft elastomers are experimentally tested with a magnetic setup to evaluate their dry-coupled efficiency. Samples with different materials and thicknesses are experimentally tested to select the best configuration for dry ultrasonic coupling. The softest elastomer tested yielded the best ultrasonic efficiency (AC-to-AC) of 68% at 1 MHz. A full DC-to-DC portable (battery-operated) UPT system was then developed and experimentally characterized. The system was capable of delivering up to 3 W of DC power to a resistive load with a total efficiency of 50%.

Quality assurance: a vital aspect of the clinician's role.

Medical professionals are ethically obligated to document the quality of the care they provide for patients. Society's demands and patients' expectations make quality assurance an issue of concern to all health care providers. The Joint Commission on Accreditation of Healthcare Organizations has formulated a detailed process for monitoring clinical activities and evaluating quality. This report reviews the rationale for and recommended approach to monitoring and evaluating quality assurance.

Role of specific dopamine receptor subtypes in amphetamine discrimination.

Biochemical, electrophysiological, and behavioral experiments suggest that the dopamine D-1 and D-2 receptor subtypes functionally interact. In rats trained to discriminate 1.0 mg/kg d-amphetamine, substitution with the D-2 agonist quinpirole (0.1-2.0 mg/kg) produces amphetamine-lever responding, whereas the D-1 agonist SKF 38393 (0.3-10.0 mg/kg) elicits only saline-appropriate responding. Combining either quinpirole (0.05-0.5 mg/kg) or SKF 38393 (0.5-10.0 mg/kg) with 0.3 mg/kg d-amphetamine results in dose-dependent increases in amphetamine-lever responding. Conversely, the D-1 antagonist SCH 23390 (0.02-0.1 mg/kg) antagonizes the discrimination produced by 0.7 mg/kg d-amphetamine. Additional combination studies examined the effect of DA receptor drugs on discrimination when quinpirole is substituted in d-amphetamine trained rats. SKF 38393 (0.5-7.0 mg/kg) fails to increase the amphetamine-appropriate lever response produced by either 0.05 or 0.2 mg/kg quinpirole. Similarly, SCH 23390 (0.01-0.1 mg/kg) fails to antagonize the amphetamine-lever responding produced by either 0.2 or 0.5 mg/kg quinpirole. Haloperidol (0.02-0.2 mg/kg) does antagonize the amphetamine-appropriate response produced by quinpirole substitution. The d-amphetamine discrimination studies indicate that stimulating D-2 receptors alone or D-1 receptors in the presence of d-amphetamine yields d-amphetamine-lever responding, and suggests that D-1/D-2 receptors can functionally interact to alter discrimination behavior. Quinpirole substitution, on the other hand, shows an insensitivity to D-1 receptor manipulations.

The effect of social support on prenatal care.

This article examines the effects of social support on the receipt of adequate prenatal care. A study was conducted to test the hypotheses that social support helps women overcome obstacles to obtaining such care, and that social support has greater effects on women facing the most obstacles. Survey data were gathered for more than 90% of the women who gave birth in Oklahoma hospitals during specific periods in the summer of 1986. The authors found only weak support for the first hypothesis, and for the second hypothesis found only support that must be qualified according to the measure of social support. Strong evidence indicates, however, that difficulty in paying for prenatal care, personal inconveniences, and unwanted pregnancies are obstacles to obtaining such care. The findings account for some of the frequently observed demographic differences associated with receipt of adequate prenatal care, although such differences persisted even after the obstacles were considered. The authors present implications for policy makers seeking to improve women's receipt of adequate prenatal care.

Race differences in age at first birth and the pace of subsequent fertility: implications for the minority group status hypothesis.

We examine race differences in the effects of age at first birth on the pace of subsequent fertility. If race differences in the pace of fertility persist net of age at first birth and socioeconomic variables, they will be taken as new support for the minority group status hypothesis. Data from the 1973 National Survey of Family Growth are analyzed with the finding that race differences in the pace of fertility are real, giving support to the hypothesis. Implications are drawn suggesting that the proper points at which to examine group differences in fertility are the different stages in the process which culminates in completed fertility, rather than limiting investigation to the final product.

Education and fertility: implications for the roles women occupy.

PIP: The interplay between education and fertility has a significant influence on the roles women occupy, when in their life cycle they occupy these roles, and the length of time spent in these roles. The overall inverse relationship between education and fertility is well known; but little is known about the theoretical and empirical basis of this relationship. This paper explores the theoretical linkages between education and fertility and examines the relationships between the 2 at 3 stages in the life cycle. It is found that the reciprocal relationship between education and age at 1st birth is dominated by the effect from education to age at 1st birth with only a trivial effect in the other direction. Once the process of childbearing has begun, education has essentially no direct effect on fertility; but it has a large indirect effect through age at 1st birth.^ieng