ON THE COLLISION DETECTION PROBLEM OF TWO MOVING OBJECTS DESCRIBED BY ALGEBRAIC SETS

In this paper, the collision problem of two moving objects is investigated. The objects are described by two algebraic sets （ellipses or circles in the paper）. The collision problem discussed involves both static and dynamic case. The static case is that each object moves with known velocity. We use nonlinear programming to decide whether the objects collide. The dynamic case is that each object is controlled by a constraint external force which can be regulated online. For the dynamic case, the collision problem can be modelled as a Minmax problem which can be solved by using differential games. If collision occurs, the time and place of the first collision are given. The moving trajectories are provided in the paper.     

Sul meccanismo di azione della streptomicina

Summary A study was undertaken on the variations of the redox potential level produced by streptomycinin vitro andin vivo. We have been able to show that, owing to an oxidative effect, streptomycin produces an increase of the redox potential level. This oxidative effect varies in degree according to the condition of the patient.We also found that in the blood and in the spinal fluid of patients suffering from tubercular meningitis factors are present which inhibit the action of streptomycin.The results of our findings lead to the conclusion that the dose of streptomycin must be varied according to the condition of the patient if the constant level required for an efficient therapy is to be maintained in the blood and in the spinal fluid.     

Kondensationsprodukte von Oxyketonen und Aminoketonen mit 2,4,5-Triamino-6-oxy-pyrimidin

Summary By condensing 2:4:5-triamino-6-hydroxy-pyrimidine with dihydroxyacetone (diacetate), diaminoacetone or acetone-1,3-di (p-formylaminobenzoic acid) not the expected 8- or 9-oxymethyl resp. -aminomethyl-pteridines but 8-or 9-methyl-pteridines were obtained. With p-tolyl-d-isoglucosamine not a tetrahydroxybutyl-pteridine but a trihydroxybutyl-pteridine was formed. For an explanation of these results it is supposed that from the dihydro-pteridines formed at first by intramolecular splitting off of H₂O or R·NH₂ aromatization takes place.     

A propos d'antibiotiques insolubles

Summary The authors show the antibiotic activity of water-insoluble salts of hydrosoluble antibiotics in the case of penicillin G (salts of iron, copper, silver, gold, and uranium) and streptomycin (oleate).     

证券投资组合理论和无差异曲线

文章通过无差异曲线解释了最优证券投资组合并探讨了对现代投资组合理论三个主要组成部分的有关内容.     

浅析基于电子商务网络安全PKI技术的角色访问控制模型

文本提出了一种区别于传统自主访问控制策略和强制访问控制策略的RBAC网络安全策略,并提出了RBAC的面向对象模型,实现用户身份认证与访问权限的逻辑分离,且易于控制,既能有效的改进系统安全性能,又极大地减少了权限管理的负担。