Sensory-feedback system compatible with myoelectric control

Progress in the development of a system to provide sensory feedback of the pinch force of an artificial hand is described. Design criteria relating to electrocutaneous stimulation and compatibility with myoelectric control are discussed. Details of a practical system, presently in use by two amputees prior to full-scale clinical evaluation, are presented.     

政策反馈理论视域：中国医疗卫生政策钟摆式变迁及其逻辑

新中国成立以来,党和国家不断强化医疗卫生建设,70余年来医疗卫生政策演进呈钟摆式变迁的特征,即从公益导向的福利性医疗卫生政策摆向效率导向的市场化政策,再摆向公益为主兼顾效率的民生导向政策,在公益与效率间发生三次摆动。本文借助政策反馈理论分析医疗卫生政策钟摆式变迁的内在逻辑,发现政策变迁过程中原有政策通过资源效应、解释效应、演化效应和学习效应影响新政策的制定,使得新政策留有原政策的烙印,呈现出摆动式变迁而非剧烈或范式变迁。政策反馈理论为医疗卫生政策制定提供新视角,制定医疗卫生政策需注重原政策的历史影响力,以公共价值引领医疗医保医药政策,从多重政策反馈效应视角出发优化卫生政策的制定。     

Relative Validity of MijnEetmeter: A Food Diary App for Self-Monitoring of Dietary Intake

This study aimed to evaluate the relative validity of intake of energy, nutrients and food groups assessed with MijnEetmeter food diary as compared to 24-h dietary recalls, and if this differed between experienced and new users. One hundred men and women aged 18–70 y participated, of whom 47 had prior experience with the tool. Participants kept MijnEetmeter on three days. Trained dietitians called them three times for a 24-h dietary recall interview, once recalling food consumption on the same day as the food recording in MijnEetmeter. Systematic differences and correlations were assessed, and Bland–Altman plots were created; both for 3-day mean intakes and for intakes on the same day. Relative to 24-h dietary recalls, MijnEetmeter underestimated consumption of drinks, added fat, cereal products, and potatoes. Relative underestimation was observed for energy intake (6%) and about half of the nutrients. Experienced MijnEetmeter users underestimated intake the least. For intake of energy and six key nutrients, correlations between 3-day mean intakes were above 0.7 except for sodium intake. In conclusion, MijnEetmeter moderately underestimates intakes of energy and some nutrients and food groups. To improve the self-monitoring of dietary intake, it is recommended that the users record food consumption for several days and that the apps probes for easily forgotten foods and drinks.     

Stabilization of positive coupled differential‐difference equations with unbounded time‐varying delays

This paper researches the static output‐feedback stabilization of single‐input single‐output (SISO) positive coupled differential‐difference equations (CDDEs) with unbounded time‐varying delays. First, a necessary and sufficient condition is provided for the positivity and asymptotical stability of CDDEs with unbounded time‐varying delays. For this type of system, based on the constructed estimates of its solution, a necessary and sufficient condition on asymptotical stability is provided. Then, based on this criterion, for CDDEs with unbounded time‐varying delays, a kind of static output‐feedback controller is designed to ensure the positivity and asymptotical stability of the corresponding closed‐loop systems. It is also worth pointing out that the controller is designed by the linear programming method without parameterization technique. This design approach can also be applied to the static state feedback stabilization problem of CDDEs with unbounded time‐varying delays. Finally, two illustrative examples are given to show the effectiveness of our results.     

人工神经网络预滤波的自适应运动心电信号增强器

运动心电图是一种将人体对象置于非平静状态下检测到的心电信号，其特点是运动导致基线严重漂移，肌电干扰显著增加，信噪比低。介绍了一种用人工神经网络预滤波的自适应运动心电信号增强器。运用人工神经网络的非线性和自适应处理的跟踪特性有机地结合设计而成。能降低噪声，提高信噪比，有效地提取运动心电信号。     

Some observations on the mechanism of pressure related atrial fibrillation

In order to investigate the effect of atrial pressure on thepropensity of the atria to fibrillate and the mechanism of thisassociation, the right atrial pressure was changed acutely bytransfusion-bleeding in 12 anaesthetized open-chest dogs. Undervarious atrial pressures the conduction time was measured betweentwo pairs of hook electrodes positioned on the two atrial appendagesrespectively. The effective refractory period was measured bycontinuous pacing of the right atrium at a 250 ms cycle lengthat double threshold intensity and interpolating a progressivelyearlier stimulus after each eighth paced beat. The propensityof fibrillation was studied by rapid (450 min^–1) pacingof the atria at double threshold intensity for 10 s at differentatrial pressures. At a high (14 mmHg) atrial pressure the conductiontime (45.7 ± 14.2 ms) was significantly (P<0.01) longer,the effective refractory period (157.9 ± 15.2 ms) significantly(P<0.01) longer and the atrial fibrillation (11/19 or 57.9%)significantly (X² = 9.95, P<0.001) more common than at alow ( 10 mmHg) pressure (35.2 ± 11.6, 146.2 ±12.4, 3/24 or 12.5%, respectively). Analysis of variance showedthat the probability of atrial fibrillation was significantlyaffected by the atrial pressure but not by either the conductiontime or the effective refractory period The findings suggestthat an increase in right atrial pressure by acute volume overloadprolongs the inter-atrial conduction time and right atrial refractorinessand increases the propensity of the atria tofibrillate by rapidatrial stimulation. The effect of atrial pressure on fibrillationdoes not seem to be mediated by the prolonged atrial refractorinessor conduction time.     

The diluting effect of medical work groups on feedback efficacy in changing physician's practice

Feedback intervention has been advocated as a successful method to modify the way that physicians practice medicine. However, most studies concerned with modifying physician profiles have focused on interns and residents. The results presented here concern regular staff and therefore provide a better basis for generalization. Over a 2.5-year period, we analyzed the use of clinical resoucces by physicians practicing in four medical specialties in two hospitals. Hierarchical multiple regression models were used to control case mix in order to identify the specific effects attributable to feedback. The information failed to modify the physicians' practice profiles. Our results suggest that this failure is related to the organization of inpatient medical practice as a group effort. This mode of practice has a negative effect on feedback efficacy. First, it weakens one of the main feedback mechanisms, that is personal identification with the data. Second, it probably generates mutual adjustment among physicians, thus eliminating practice variations at the source.     

Effect of age on the prejunctional α-adrenoceptor-mediated feedback in the heart of spontaneously hypertensive rats and normotensive Wistar Kyoto rats

Summary The prejunctional ₂-adrenoceptor-mediated feed-back in the heart of pithed young and adult spontaneously hypertensive rats (SHR) and corresponding normotensive Wistar Kyoto rats (WKY) was studied. After electrical stimulation of the sympathetic outflow from the spinal cord to the heart, B-HT 920 induced an inhibition of the cardiac response, which was significant at stimulation frequencies up to 1 Hz in young SHR and WKY and up to 2 Hz in the adult animals. Rauwolscine produced a potentiation of the cardiac response to electrical stimulation in SHR, which was significant from 0.2–10 Hz in young SHR and from 0.1–10 Hz in adult SHR. In young WKY, rauwolscine did not potentiate the increase in heart rate to sympathetic nerve stimulation, whereas in adult WKY ₂-adrenoceptor blockade by rauwolscine significantly potentiated the cardiac response to electrical stimulation at frequencies in the range of 0.2–10 Hz. In SHR the potentiation of the cardiac response to sympathetic nerve stimulation by rauwolscine was much stronger than in WKY.These results suggest that in adult animals the prejunctional ₂-adrenoceptor mediated feedback is more developed than in young rats. In contrast with young WKY, a significant endogenous feedback can be demonstrated in adult WKY. In SHR, however, the physiological role of prejunctional ₂-adrenoceptors is much more important.     

Evidence that Dopaminergic Neurons are not Involved in the Negative Feedback Effect of Testosterone on Luteinizing Hormone in Rams in the Non-Breeding Season

In this study we tested the hypothesis that the negative feedback effects by testosterone on the secretion of luteinizing hormone (LH) in rams involves dopaminergic afferents to gonadotrophin-releasing hormone neurons operating via D(2) receptors in the non-breeding season. In the first experiment, three groups (n = 5) of rams were treated with an intravenous injection of vehicle or 10 or 20 mg of the dopaminergic D(2) antagonist pimozide and jugular venous samples were collected every 10 min for 3 h before and 3 h following treatment. The plasma was assayed for LH. Three groups of ewes (n = 4 to 5) were similarly treated. There were no significant effects of treatment of the rams with pimozide on the plasma concentrations of LH or LH pulse frequency or pulse amplitude and the response of individual rams in each group was inconsistent. In contrast, treatment of the ewes with 20 mg pimozide significantly (P<0.001) increased the mean (± SEM) plasma LH concentrations (pretreatment 0.37 ± 0.04; post-treatment 2.42±0.25 ng/ml) and decreased (P<0.001) the LH inter-pulse interval (pretreatment 180.0; post-treatment 88.0±11.1 min); the 10 mg dose of pimozide did not affect these parameters. In the second experiment, two groups of rams (n = 5) and ewes (n = 7) were treated with an intravenous injection of vehicle or 0.33 mg pimozide/kg liveweight and jugular venous samples were collected every 10 min for 2 h before and 6 h following treatment. As in the first experiment, the mean (± SEM) concentrations of plasma LH were not affected by treatment with pimozide in the rams (pretreatment 0.18 ± 0.25; post-treatment 0.43 ± 0.14 ng/ml) but were significantly (P<0.05) increased in the ewes (pretreatment 1.12±0.22; post-treatment 1.93 ± 0.23 ng/ml). In the third experiment, four adult rams were castrated and 3 weeks later each animal had two cannulae inserted to allow injection into the lateral cerebral ventricles. Vehicle or 100 μg pimozide was injected intracerebroventricularly and blood samples were collected as in the other experiments. A Latin Square design was used so that each animal received each treatment (n = 4). This procedure was repeated after the animals had been injected (intramuscularly) with 16 mg testosterone propionate twice daily for at least 7 days. Treatment with testosterone propionate significantly decreased (P < 0.001) the plasma concentrations of LH (pre-treatment 7.71±0.27; post-treatment 0.75 ± 0.27 ng/ml; mean ± SEM) and follicle-stimulating hormone (pre-treatment 79.61±8.47; post-treatment 42.53 ± 6.08 ng/ml; mean ± SEM) and increased the mean (± SEM) LH inter-pulse interval (53.14 ± 3.58 min pre-treatment and 292.5 ± 32.94 min post-treatment) but had no effect on the amplitude of LH pulses (pre-treatment 3.61 ± 0.36; post-treatment 1.86±1.76 ng; mean ± SEM). Pimozide had no effect on the plasma concentrations of gonadotrophins. These results suggest that, in the ram, dopaminergic neurons do not influence the gonadotrophin-releasing hormone neurons via D(2) receptors in the non-breeding season and are not involved in the negative feedback effect of testosterone on the secretion of gonadotrophins. Conversely, our data suggest that such a mechanism is integral to the negative feedback effects of oestradiol on LH in anoestrous ewes. Finally, it also appears that the steroid-independent suppression of the secretion of gonadotrophins during the non-breeding season in rams is not mediated via D(2) receptors.     

Blockade of presynaptic α-receptors and of amine uptake in the rat brain by the antidepressant mianserine

Summary Mianserine (Org GB 94, Tolvon^®) is 1, 2, 3, 4, 10, 14b-hexahydro-2-methyl-dibenzo [c, f] pyrazino [1, 3-a] azepine hydrochloride, a new antidepressant drug. Its effect on noradrenaline release and its capacity to inhibit amine uptake were investigated. Mianserine increased the release of ³H-noradrenaline from field-stimulated cortical slices previously labelled with the tritiated transmitter. The assumption that this effect is due primarily to the blockade of the presynaptic noradrenergic -receptors is supported by the fact that mianserine failed to augment ³H-noradrenaline release further after blockade of the presynaptic -receptors by phentolamine. In the reciprocal experiment, phentolamine failed to augment ³H-noradrenaline release after exposure of the slices to mianserine. The hypothesis is further reinforced by the fact that mianserine antagonized the reduction of ³H-noradrenaline release by clonidine in the same manner as the -blocking drugs phentolamine and phenoxybenzamine. Mianserine inhibited noradrenaline uptake in vitro and in vivo (in the rat heart and midbrain-diencephalon synaptosomes from pretreated rats.) Only a marginal inhibition of serotonin uptake was observed.It therefore appears that mianserine increases the concentration of noradrenaline in the synaptic cleft by blocking the presynaptic -receptors and inhibiting uptake. Whether or not this increase has functional consequences at postsynaptic noradrenergic receptor sites is unknown. It is possible, however, that postsynaptic receptor blockade counteracts the increase in available noradrenaline.A part of these results was presented at the 16th Spring Meeting of the German Pharmacological Society, Mainz, March 4–7, 1975