具size结构种群竞争系统的最优控制

研究基于size结构的种群模型的控制问题,利用特征线法给出了系统的形式解,由Banach不动点定理和Gronwall不等式推导了系统及其共轭系统的适定性,并依靠法锥相关知识证明了最优控制问题解的存在必要条件.     

Decarboxylation and carboxylation of pyruvate in the living mice.

Mice received intravenously [1- or 2-14C]acetate, [1-, 2- or 3-14C] or [2-14C]pyruvate and were killed 1, 3, 5 or 15 min later. The radioactivity of CO2 or HCO3- of liver or carcass as well as the radioactivity of blood glucose were measured. The ratio of the radioactivity found in these compounds after [3-14C] or [2-14C-A1pyruvate injection suggests that in the fed aminals: 1. the decarboxylation of the pyruvate was more rapid than its carboxylation, 2. most of the neosynthesized glucose was derived from pyruvate molecules which had undergone a decarboxylation followed by a condensation to citrate, 3. 1/4 to 1/3 of the pyruvate was carboxylated and 2/3 to 3/4 was decarboxylated in animals receiving a diet poor in fats.     

Inhibition of the hyperglycemic effect of cAMP by intravenous injection to mice of carbonic anhydrase entrapped in liposomes.

Mice treated with acetazolamide or cAMP received intravenously liposomes containing carbonic anhydrase. The hyperglycemic effect of both these substances was suppressed by carbonic anhydrase entrapped in liposomes. The later also abolished the glycogenolytic action of cAMP on liver.     

Physical fitness of the Czechoslovak population between the ages of 12 and 55 years. Pulmonary ventilation.

Examination of ventilation function in an average population showed that maximum minute ventilation in adults fell with advancing age. Males had higher values than females, the highest values being attained, in both sexes, at 18 (117 and 83 1/min respectively). Tidal volume during loading, expressed as a percentage of vital capacity, rose with advancing age in all groups of males and females (from 53% at 18 to 64% at 55 in males and from 51% to 59% in females). The ventilation equivalents for O2 and CO2 attained optimum values at a load of 100 W in males and at 50 W in females. On increasing the load they rose in both sexes--in females more than in males. Percentual utilization of O2 from the inspired air was greatest in males at a load of about 100 W (4.8--5%) and in females at about 50 W (4.3--4.8%). At higher loads it fell faster in females than in males. In males, the respiratory quocient attained the value 1 at a load of about 2 W/kg body weight and in females at 1.5 W/kg. At maximum loading it was over 1 in all the age categories. No differences between males and females were observed, but males, in maximum loading, gave the greatest absolute and the greatest relative performance.     

Effect of PGE1 on gluconeogenesis and glycerol esterification in perfused liver of fasted rats.

Using perfused livers of rats fasted for 48 hours, glucose production and incoroporation of 2-14C pyruvate (trace dose) into perfusate glucose were studied. Both were found to be inhibited by PGE1 (infuced at a concentration of 0.5 mu/min) by about 60%. The incorporation of 1-14C glycerol into perfusate glucose and into glycerol-glyceride part of the liver glycerides were also studied, using the same test conditions. The former incorporation was significantly inhibited (56%) and the latter strongly stimulated (360 %) by PGE1. PGE1 had no effect on glucose production in a perfusate overloaded with sodium pyruvate, nor on pyruvate carboxylase and phospho-enolpyruvate carboxykinase activity. this was in contrast with the results obtained in perfusions with a trace dose of 2-14C pyruvate. The results showed that PGE1, at the physiological concentration used, stimulated the incorporation of 1-14C glycerol into glycerol-glyceride part of liver glycerides and, when there was no overload of pyruvate present in the perfusion medium, inhibited gluconeogensis at some point, possibly, but perhaps not exclusively, between the glycerol and glucose steps.