Non-linear stability of vortex formation in swarms of interacting particles

We use a particle-based model of a swarm of interacting particles to explore analytically the conditions for the formation of vortexlike behavior. Our model uses pairwise interaction potentials to model weak long-range attraction and strong short-range repulsion with a dissipation function to align particle velocity vectors. We use the effective energy of the swarm as a Lyapunov function to prove convergence to a vortexlike state. Our analysis extends previous work which has relied purely on simulation to explore the formation and stability of vortexlike behavior through analytical rather than numerical methods

An emergent wall following behaviour to escape local minima for swarms of agents

Natural examples of emergent behaviour, in groups due to interactions among the group's individuals, are numerous. Our aim, in this paper, is to use complex emergent behaviour among agents that interact via pair-wise attractive and repulsive potentials, to solve the local minima problem in the artificial potential based navigation method. We present a modified potential field based path planning algorithm, which uses agent internal states and swarm emergent behaviour to enhance group performance. The algorithm is used successfully to solve a reactive path-planning problem that cannot be solved using conventional static potential fields due to local minima formation. Simulation results demonstrate the ability of a swarm of agents to perform problem solving using the dynamic internal states of the agents along with emergent behaviour of the entire group

إنتاج مادة 17 ألفا هيدروكسي البروجستيرون على مستوى المخمر المعملي بواسطة فطرة كاننجهاميلا إيكينولاتا

The mircrobiological transformation of progesterone by a local isolate of Cunninghamella echiiiulata using a laboratory fermentor was studied. Progresterone (10-50 g/1) wetted by Tween 80 was added to 48-hour old culture and the transformation was left to proceed for 72 hours. Thereafter, the different transformation products were resolved chromatog-raphically. The identity of each product was established through the determination of m.p., mixed m.p., optical rotation and ultraviolet as well as infrared absorption spectra. A comparison of the R{ values of each product with that of the corresponding reference using different solvent systems as well as their colour expressed with two spray reagents, was used as a further proof for the identity of the isolated products. With all concentrations of progesterone tested, maximum yield of 17ot -hydroxyprogesterone was obtained after 48 hours of fermentation Progesterone concentrations of 10 and 20 g/1 were almost quantitatively converted to the different transformation products after 72 hours of fermentation. Using a concentration of 20 g/1 and incubation period of 48 hours, the transformation product mixture consisted of unchanged progesterone (6%), 17 o< -hydroxyprogesterone (54%),llotrhydroxyprogesterone (29%) and llo<;,17<^-dihydroxy-progesterone (2.5%).تم استخدام مخمر صناعي سعة 2 لتر لاختيار مقدرة الفطرة على تكوين هذه المادة في ظروف تشبه تلك المطبقة في الصناعة . وبدراسة تركيزات متعددة فن مادة البروجستيرون تتراوح ما بين 10جرام /لتر إلى 50جرام /لتر ، وجد أن أنسب التركيزات المختبرة هو تركيز 20 جرام من البروجستيرون لكل لترمن الوسط الغذائي ، حيث تم تحويل كل البووجستيرون المضاف إلى المشتقات المختلفة خلال 72 ساعة من بدء الاضافة . ووجد أن أعلى معدل لتكوين مادة 17 ألفا - هيدروكسي البروجستيرون كان بعد 48 ساعة من بدأ إضافة البروجستيرون . عند فصل المواد الناتجة من تحول البروجستيرون بواسطة الفطرة المستخدمة وذلك بواسطة أعمدة الفصل باستخدام مادة الالومينا وجد أن البروجستيرون يتحول إلى : 17 ألفا - هيدروكسي البروجستيرون ( 54 %) 11 ألفا - هيدروكسي البروجستيرون (29%) 11 ألفا ، 17 ألفا - ثنائي هيدروكسي البروجستيرون (2.5%