Wearable devices for telemedicine applications.

Wearable medical devices can provide both continuous monitoring and ubiquitous treatment. Challenges in this area include the need for a low-power/power-saving design to extend battery life and to reduce the size of the battery itself. This is followed by size and weight restrictions to meet patient expectations of what is 'wearable', the biocompatibility of all outer housings and the final assembly concept. Two examples of wearable medical device are described: a wrist-wearable telemedicine monitor for heart patients (AMON) and a generic belt-integrated computing platform for home and hospital use (QBIC). The electrocardiogram (ECG), the blood oxygen saturation (SpO2) sensor and the blood pressure meter of the AMON device were tested with 29 subjects. The sensors were found to be functional, but as expected the data processing algorithms will need some fine-tuning. The prototype QBIC demonstrates a size reduction of 30-50% in relation to comparable devices.

Wearable devices for emerging healthcare applications.

Today's quality of life is supported by medical capabilities that have not been available years ago. These capabilities are not limited to disease treatment only, indeed there has been a paradigm shift to disease prevention and monitoring. Especially continuous monitoring of patients or even of people who are only interested in their health has received increasing interest. Thus, the need and the potential to miniaturize lab-scale monitoring devices have inspired many research projects and start-up companies to create new or to miniaturize medical applications. Challenges in this area comprise low-power/power saving design to extend battery life and to reduce the size of the battery itself. This is followed by size/height/weight reductions to meet user expectations of being "wearable", biocompatibility of all outer housings, and the final assembly concept. Instead of using a sequential design approach, the complexity mandates to handle all aspects concurrently as early as possible in the design phase. Already during this design phase HDP (high-density packaging) technologies help to meet the size requirements without sacrificing too much flexibility and violating time/cost constraints. This paper will present two miniaturization design strategies, considerations and solutions for two novel medical applications in the health monitoring area.

First human experiments with a novel non-invasive, non-optical continuous glucose monitoring system.

This paper describes a non-invasive continuous glucose monitoring system based on impedance spectroscopy. Changes in the glucose concentrations can be monitored by varying the frequency in the radio band over a range, optimised to measure the impact of glucose on the impedance pattern. A number of clinical-experimental studies (hyperglycaemic excursions) were performed with healthy subjects in order to prove the applicability of this approach. The sensor used in these experiments is the size of a wristwatch and holds an open resonant circuit coupled to the skin and a circuit, performing an impedance measurement. In most cases, the experiments showed a good correlation between changes in blood glucose and the sensor recordings. A detailed description of the trials is presented. The results of this first series of experiments can be considered as a proof of concept for this novel non-invasive monitoring approach. Nevertheless, partly due to the indirect measurement, a considerable number of questions remain to be clarified.

When expectancy meets desire: motivational effects in reconstructive memory.

Two studies investigated the effects of motivational factors on expectancy use in reconstructive memory. Participants were given target's midterm grades for later recall; expectancies about the target's future performance were then manipulated. Participants' desires to see their expectancies confirmed were manipulated by making the target likable or unlikable. The authors hypothesized that when expectancy and liking "matched," participants would give significant weight to their expectancies at retrieval, resulting in expectancy-congruent distortion of the midterm grades. However, when expectancy and liking were "mismatched," expectancies would be discontinued, and participants would show little or no expectancy-congruent distortion. Results supported these predictions. Study 2 varied the order of the expectancy and liking information. Order affected the process by which mismatch participants discounted their expectancies. Results demonstrate that motivations not only may bias memory search but also may affect the reconstruction of existing memory traces.

Processing goals, task interest, and the mood-performance relationship: a mediational analysis.

The authors examined the role of intrinsic interest in mediating the relationship among mood, processing goals, and task performance. Participants in induced happy, neutral, or sad moods generated similarities and differences between TV shows using performance-based, enjoyment-based, or no stop rule (cf. L.L. Martin, D.W. Ward, J.W. Achee, & R.S. Wyer, 1993). Pretask interest and both quantitative (time spent, number generated) and qualitative (creativity) performance were assessed. Happy participants spent more time and generated more items than other participants when using an enjoyment-based stop rule but spent less time and generated fewer items when using a performance-based stop rule. Happy participants also expressed greater pretask interest and were more creative than other participants regardless of stop rule. Regression-based path analyses indicated that pretask interest partially mediated the effects of mood on quantitative performance but not on creativity.

Self-reported versus behavioral self-handicapping: empirical evidence for a theoretical distinction.

The present study was an investigation of how Ss would respond when given 2 self-handicapping options, 1 behavioral (withdrawal of practice effort) and 1 self-reported (reporting high levels of stress). Ss anticipating a diagnostic test of intellectual ability were given different instructions regarding the effects of stress and practice on test performance. Ss were told that (a) stress only, (b) practice only, (c) both stress and practice, or (d) neither stress nor practice affected test scores. Ss were then given the opportunity to self-report a handicap on a stress inventory and to behaviorally self-handicap by failing to practice before the test. High self-handicapping men and women showed evidence of self-reported handicapping, but only high self-handicapping men behaviorally self-handicapped. However, when both self-handicaps were viable, both high self-handicapping men and women preferred the self-reported over the behavioral self-handicap.

Probability and category redefinition in the fault tree paradigm.

Fault trees have been advocated as aids for problem solvers. However, research has suggested limitations in their usefulness. Fischhoff, Slovic, and Lichtenstein (1978) found that subjects given incomplete (pruned) trees were insensitive to omissions; these authors hypothesized that Tversky and Kahneman's (1974) availability heuristic was the mediating factor. Using a within-subjects design, subjects in Experiment 1 received both full and pruned trees and estimated probabilities for various reasons why a car would fail to start. To increase the availability of omissions, some Experiment 1 subjects first generated possible causes of starting failure. The basic Fischhoff et al. findings were replicated, but several aspects of the results argued against the availability hypothesis as the mechanism for judgment. Instead, subjects appeared to idiosyncratically redefine category membership when making judgments based upon pruned trees. By employing a sorting task in Experiment 2 we corroborated the results of Experiment 1: Subjects do redefine the actual contents of the categories when faced with an omission from the fault tree. The implications of these results for the use of fault trees as a problem solving aid are discussed.

Vascular relaxation and cGMP in hypertension.

Isolated aortas from hypertensive rats have a decreased relaxation response to acetylcholine chloride (ACh), the calcium ionophore A23187, and sodium nitroprusside (SNP). Since the vascular relaxation responses to these vasodilators may be a result of increases in guanosine 3',5'-cyclic monophosphate (cGMP), we measured the cGMP response to these agents in isolated aortas from normotensive rats and rats with either mineralocorticoid-induced hypertension (DOCA), renovascular hypertension (1K1C), or coarctation-induced hypertension (Coarc). The aortas from the hypertensive rats had decreased basal levels of cGMP and attenuated increases in cGMP in response to ACh and A23187. Rises in cGMP in response to SNP were also attenuated in aortas from the hypertensive rats, even at concentrations that induced maximum relaxation of blood vessels from normotensive and hypertensive rats. The relaxation responses to atrial natriuretic factor (ANF) and the cGMP generated in isolated aortas by ANF were attenuated in hypertension. Removal of the endothelium markedly attenuated cGMP generation in response to ANF in vessels from normotensive and Coarc rats, but the relaxation responses to ANF were unaltered in vessels after the removal of the endothelium. The reversal of experimentally induced hypertension was associated with increases in cGMP levels following exposure of the isolated vessels to ACh. Also, vessels treated with methylene blue relaxed in response to SNP despite inhibition of cGMP accumulation. The decreased relaxation response to endothelium-dependent vasodilators is accompanied by decreases in cGMP accumulation; the decreased vascular cGMP content in response to endothelium-dependent vasodilators is not due to increases in phosphodiesterase activity of vascular smooth muscle; and SNP may relax blood vessels through "cGMP-dependent" and "cGMP-independent" mechanisms.

The endothelium and cyclic guanosine monophosphate in hyperthyroid-induced hypertension.

We investigated the role of endothelium derived relaxing factor (EDRF) and cyclic guanosine monophosphate (cGMP) in the altered vascular reactivity of hyperthyroidism (HT). Rats were given daily injections of triiodothyronine (T3), 50 micrograms/100 g body weight for two weeks, and they had significantly higher serum levels of T3 compared to untreated, control rats (493 +/- 82 vs. 58 +/- 7 ng/dl, p less than 0.05) and significant elevations in their systolic blood pressure (188 +/- 6 vs 126 +/- 3 mm Hg, p less than 0.05). Vascular reactivity was studied in isolated muscle baths; cGMP was measured by RIA. There were no differences in contractile responses to phenylephrine (PE) in isolated aortae from the HT and control rats, but aortae from the HT rats contracted with PE relaxed less to acetylcholine (Ach); the calcium ionophore, A23187; and sodium nitroprusside (SNP). Sensitivity to atrial natriuretic factor (ANF) and 8-Br cGMP was unaltered. Blood vessels from HT rats generated significantly less cGMP in response to Ach, SNP, and ANF. Treatment of the hypertension in the HT rats which hydralazine or propranolol restored the vascular relaxation response to Ach but not SNP; cGMP responses remained blunted. These data suggest that endothelium dependent vasodilators may induce relaxation independent of elevations of cGMP in aortae from HT rats.