FEEDBACK CONTROL OF A HEAT DIFFUSION SYSTEM WITH TIME-DEPENDENT SPATIAL DOMAIN

The problem of controlling the temperature distribution in a solid cylinder whose length varies with time and with one end in contact with a constant temperature medium is considered. This problem is motivated from that of controlling the temperature and thermal gradient inside a crystal pulled from a melt by the Czochralski method. Boundary feedback controls are derived by considering the time rate of change of a cost functional involving the deviations of both the solid temperature and its gradient from their desired values. The derived feedback controls consist of spatially distributed proportional-plus-rate and lag compensators and a non-linear feedback control involving the temperature gradient at the cylinder surface and the velocity of the spatial domain boundary. The resulting feedback-controlled system has the property that the cost functional along any motion decreases monotonically to zero with time. A numerical scheme for solving the partial differential equation of the feedback-controlled system is proposed. Typical numerical results on the dynamic behaviour of the feedback-controlled system obtained by means of the proposed scheme are presented.     

补碘对7～12岁轻度碘缺乏病儿童脑功能及生长、发育的影响

通过半年对３５名７～１２岁轻度碘缺乏病儿童进行补碘，并与同龄、同地的正常儿童和缺碘未补碘儿童进行比较，以观察补碘对儿童脑功能及生长发育的影响。结果发现：①补碘可使儿童碘营养状况恢复正常，尿碘值由（８３．２±３．５）μｇ／Ｌ上升到（１６２．２±１．６）μｇ／Ｌ，血清Ｔ４、ＦＴ４Ｉ和ｒＴ３：也与正常儿童一致而与未补碘儿童有显著性差异（Ｐ＜０．０５）．②轻度碘缺乏病儿童智商低于正常儿童（Ｐ＜０．０１），补碘在一定程度上改善其智商水平。③轻度碘缺乏病及补碘未能明显影响儿童的生长发育，可能与儿童总营养水平较差有关。     

Peak Endocardial Acceleration-Based Clinical Testing of the "BEST" DDDR Pacemaker

The peak endocardial acceleration (PEA, unit g) shows a near correlation with myocardial contractility during the isometric systolic contraction of the heart (dP/dtmax), with sympathetic activity and, thus, with physiological heart rate modulation. The (Biomechanical Endocardial Sorin Transducer (BEST) sensor is incorporated in the tip of a pacing lead and measures PEA directly near the myocardium. In an international study, the lead was implanted with the dual chamber pacemaker Living-1 (Sorin) in 105 patients. The behavior of the PEA signal was tested under conditions of physical and mental stress and during daily life activities by 24-hour recordings of PEA (PEA Holter) at 1 to 2 months and approximately 1 year after implantation. Implantation of the BEST lead was performed without complications in all patients. The sensor functioned properly in the short- and long-term in 98% of patients. Although PEA values differed from patient to patient, the values closely reflected the variations in sympathetic activity due to physical and mental stress in each patient. During exercise and during daily life activities a close correlation between PEA and heart rate was observed among patients with normal sinus rhythm. Peak endocardial acceleration allows a nearly physiological control of the pacing rate.     

复方18甲基炔诺酮透皮控释传递系统的LNG人体药物动力学与药效学评价

复方18甲基炔诺酮/雌二醇透皮控释传递系统(LNG/E_2 TCDS)能同时恒速释放低剂量的LNG和E_2,在1周内维持一个平稳而有效的LNG血药浓度。药动学与药效学研究证明,该系统释放的LNG能达到血清LNG目标水平,产生有效的排卵抑制(6/6)。LNG/E_2 TCDS可望发展成为一种安全、有效、非侵入性的新型生育调节避孕制剂。     

Lactation-induced plasticity in the supraoptic nucleus augments axodendritic and axosomatic GABAergic and glutamatergic synapses: an ultrastructural analysis using the disector method

The disector, an unbiased stereological method for evaluation of synaptic densities, was used to analyse putative GABA and glutamate innervations of the supraoptic nucleus of virgin and lactating rats. The analysis was performed on ultrathin sections labelled for either of the amino acids with a postembedding immunogold technique. Our observations showed that the volume of the nucleus increased by 40% in lactating animals, an increase due to a significant enlargment of dendritic and somatic, but not vascular, volumes. Nevertheless, values of overall synaptic densities in the whole nucleus remained as high as those in virgin rats (37–40×10⁶ synapses/mm³). About 45% of all synapses were immunoreactive for GABA and 25% for glutamate; there were twice as many GABA- and glutamate-positive synapses on dendrites as on somata. When we estimated synaptic densities in relation to the neuropil (by subtracting the proportion of sampled areas occupied by somatic profiles), we found a significant increase in synaptic density in lactating animals. This affected axodendritic as well as axosomatic synapses, immunopositive and immunonegative for GABA or glutamate. The disector also allowed us to determine that the number of synapses from terminals making contacts on several somata and/or dendrites simultaneously constituted about 9% of all synapses in virgin rats, a proportion which more than doubled in lactating rats. About 50% were immunopositive for GABA and 30% for glutamate.

Our data offer further evidence of physiologically-linked structural synaptic plasticity in the supraoptic nucleus and clearly demonstrate that it affects both inhibitory and excitatory inputs on dendrites, as well as on somata, throughout the nucleus.     

EFFECT OF CROSS-FOSTERING ON NEONATAL SODIUM BALANCE AND ADULT BLOOD PRESSURE IN THE SPONTANEOUSLY HYPERTENSIVE RAT

1. The aim of the present study was to compare electrolyte handling in naturally reared neonatal spontaneously hypertensive rats (SHR) with those reared by a Wistar-Kyoto (WKY) rat foster mother (denoted SHRX), as cross-fostering SHR pups to a WKY rat dam lowers adult blood pressure in the SHR. 2. The electrolyte content of WKY rat and SHR dams’ milk was determined and electrolyte intake and urinary excretion rates were calculated in both naturally reared and cross-fostered WKY rat and SHR pups. 3. The milk sodium concentration fell in both strains (WKY rat: 31.8 ± 2.0 to 15.2 ± 1.2 mmol/L; SHR 31.9 ± 2.5 to 18.2 ± 1.6 mmol/L; P < 0.001), as did potassium (P < 0.001), over lactation, but there were no differences between strains. Calcium and magnesium concentrations increased (P< 0.001), although SHR dam's milk contained less calcium (P < 0.001) than that of WKY rat dams during the third week of lactation. 4. Spontaneously hypertensive rat pups ingested less milk (P<0.05) than WKY rat pups; therefore, their cumulative sodium intake over postnatal days 4–15 was significantly lower than that of WKY rat pups (WKY rat vs SHR: 84.4 ± 3.6 vs 59.7 ± 2.6 μmol/g bodyweight, respectively; P < 0.05) and fostered SHRX pups (77.7 ± 7.0 μmol/g bodyweight; P < 0.05). Potassium and magnesium intakes were comparable between SHR, WKY rat and SHRX pups, but SHR pups ingested significantly less calcium than either WKY rat pups (136.1 ± 6.4 vs 200.1 ± 9.5p, mol/g bodyweight, respectively; P<0.05) or SHRX pups (200.0 ± 18.0 μmol/g bodyweight; P<0.05). 5. These data show that the neonatal SHR experiences a period of sodium deficiency during the developmental stage when cross-fostering is effective in lowering blood pressure. This is consistent with the reported up-regulation of the renin-angiotensin system observed in SHR at this time and may have a long-term influence on blood pressure.     

RENIN GENE POLYMORPHISM ASSOCIATED WITH ALDOSTERONE RESPONSIVENESS TO THE RENINANGIOTENSIN SYSTEM IN PATIENTS WITH ALDOSTERONE-PRODUCING ADENOMAS

1. Aldosterone levels in patients with unilateral aldosterone-producing adenomas may be responsive or unresponsive to the renin-angiotensin system, with the former often previously misdiagnosed as bilateral adrenal hyperplasia. 2. In tumours from patients in the responsive subgroup, renin mRNA is expressed in greater amounts than in tumours from patients in the unresponsive subgroup, or in normal adrenals. 3. We compared the frequency of four renin gene polymorphisms in peripheral blood DNA from the two subgroups and found significant associations between BglI, TaqI and HinfI restriction fragment length polymorphisms (RFLP) and aldosterone responsiveness. 4. Allelic variation in the constitutive renin gene was associated with a specific cause of hypertension.