Hot and repulsive traffic flow

We study a message passing model, applicable also to traffic problems. The model is implemented in a discrete lattice, where particles move towards their destination, with fluctuations around the minimal distance path. A repulsive interaction between particles is introduced in order to avoid the appearance of traffic jam. We have studied the parameter space finding regions of fluid traffic, and saturated ones, being separated by abrupt changes. The improvement of the system performance is also explored, by the introduction of a non-constant potential acting on the particles. Finally, we deal with the behavior of the system when temporary failures in the transmission occurs.Comment: 22 pages, uuencoded gzipped postscript file. 11 figures include

Primal-dual stability in continuous linear optimization

Any linear (ordinary or semi-infinite) optimization problem, and also its dual problem, can be classified as either inconsistent or bounded or unbounded, giving rise to nine duality states, three of them being precluded by the weak duality theorem. The remaining six duality states are possible in linear semi-infinite programming whereas two of them are precluded in linear programming as a consequence of the existence theorem and the non-homogeneous Farkas Lemma. This paper characterizes the linear programs and the continuous linear semi-infinite programs whose duality state is preserved by sufficiently small perturbations of all the data. Moreover, it shows that almost all linear programs satisfy this stability property.This research was supported by DGES and FEDER, Grant MTM2005-08572-C03-01 and partially supported by CONACyT of MX.Grant 44003

Ganglioglioma da região da pineal: relato de caso Ganglioglioma of the pineal region: case report

Os gangliogliomas são neoplasias mistas, compostas de elementos gliais e neuronais, extremamente raros na região da glândula pineal. Na presente revisão da literatura foram encontrados oito casos publicados. Apresentamos o caso de paciente de 14 anos, masculino, com ganglioglioma da região da pineal, tratado cirurgicamente, com exérese total da lesão por via suboccipital transtentorial. O estudo histológico mostrou tratar-se de ganglioglioma grau I, confirmado por imuno-histoquímica. Conclui-se que tais tumores são raros e que se deve optar pela cirurgia, objetivando a exérese total. Quando isso não for possível, ou no caso de recorrência, o paciente deve ser acompanhado clínica e radiograficamente, considerando-se a radioterapia como tratamento complementar.<br>Ganglioglioma are tumors presenting neoplastic glial cells and nerve cells, very rarely found in the pineal region. Only eight cases have been previously published in the literature. We present the case of a 14 years-old male patient with a ganglioglioma of the pineal region. The patient was treated surgically by a suboccipital transtentorial approach with complete removal. Histopathologic specimens with immunostainning revealed a ganglioglioma grade I. We conclude that these tumors are rare and should be treated surgically aiming total remove. If it is not possible or in case of recorrence the patient should be followed and radiotheraphy could be considered

Endovascular treatment of cerebral aneurysms: a retrospective study of 163 embolized aneurysms Tratamento endovascular de aneurismas cerebrais: estudo de 163 aneurismas embolizados

OBJECTIVE: To present the results of cerebral aneurysms treated by endovascular technique. METHOD: Retrospective analysis of patient files of Hospital Geral de Fortaleza, Brazil. RESULTS: We report the results of 163 cerebral aneurysms treated by endovascular techniques from January 2002 to October 2005. Patients with ruptured aneurysms (87.2%), according to Hunt-Hess scale were: 33.7% HH I, 28.4% HH II, 24.1% HH III, 13.8% HH IV. The Fisher scale grade IV was the most common (39.7%). Remodeling, coil embolization, arterial occlusion and histoacryl embolization were the techniques employed. Effective occlusion was achieved in 87.7%, partial occlusion in 5.3% and non-effective occlusion in 7.0% of the patients. Glasgow outcome scale results were: 76.3% GOS 5, 5.0% GOS 4, 5.8% GOS 3, 1.4% GOS 2 and 11.5% GOS 1. CONCLUSION: Endovascular treatment seems to be feasible within Brazilian public health system, with results as good as those obtained in larger international centers.<br>OBJETIVO: Apresentar os resultados de aneurismas tratados pela técnica endovascular. MÉTODO: Análise retrospectiva de prontuários do Hospital Geral de Fortaleza, Brasil. RESULTADOS: Apresentamos os resultados de 163 aneurismas cerebrais tratados por técnicas endovasculares de Janeiro de 2002 a Outubro de 2005. Os pacientes com aneurismas rotos (87,2%) eram, segundo a escala de Hunt-Hess: 33,7% HH1; 28.4% HH II, 24.1% HH III, 13.8% HH IV. O Grau IV da escala de Fisher foi o mais comum (39,7%). Empregaram-se as técnicas de remodeling, espiras metálicas, oclusão arterial e embolização com histoacryl. Foi obtida oclusão efetiva em 87,7%, oclusão parcial em 5,3% e oclusão não-efetiva em 7,0% dos casos. De acordo com a Glasgow outcome scale, os resultados foram: 76,3% GOS 5, 5,0% GOS 4, 5,8% GOS 3, 1,4% GOS 2 e 11,5% GOS 1. CONCLUSÃO: A aplicação de técnica endovasculares mostra-se viável na rede pública brasileira, com resultados comparáveis aos de grandes centros mundiais