Vasil Georgiev

Interaction of angiotensin II and adenosine receptors in pentylenetetrazol-induced kindling in mice.

The relationships of adenosine A1 receptor agonists and antagonists in combination with angiotensin II (AT II) and its analogue sarmesin in PTZ (pentylenetetrazol) kindling in ICR mice were studied. The occurrence of clonic and tonic seizures and the latency to their onset in PTZ kindled mice was determined. Combination of adenosinergic and AT II-ergic agents significantly reduced the incidence of clonic seizures in PTZ kindling without changing the latency. Pretreatment with 8-p-Sulfophenyl-theophylline (8-p-SPT) reversed the anti-convulsant effect of sarmesin.

Interaction of angiotensin II and adenosine A1 and A2A receptor ligands on the writhing test in mice

The effects of adenosine A1 and A2A receptor agonists and antagonists administered intraperitoneally (i.p.) and their interaction with angiotensin II (Ang II) administered intracerebroventricularly (i.c.v.) were studied in mice using the acetic acid-induced abdominal constriction test. Ang II (0.1 microg/mouse) induced antinociception in this model. The adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA; 0.05, 0.25 and 0.5 mg/kg) also showed a well-developed antinociceptive effect. Ang II (0.1 microg/mouse) administered 5 min before CPA (0.25 mg/kg) decreased the number of writhes, i.e., it enhanced the antinociceptive effect of CPA. Losartan, an AT1 receptor antagonist (25 microg/mouse i.c.v.), enhanced the antinociceptive effect of CPA, while the AT2 receptor antagonist 1-[-4-(dimethylamino)-3-methylphenylmethyl]-5-diphenylacetyl)-4,5,6,7-tetrahydro 1H-4-imidazol [4,5c]pyridine-6 carboxylic acid, ditrifluoroacetate, dihydrate (PD 123319; 10 microg/mouse) had less effect. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.1 mg/kg), an adenosine A1 receptor antagonist, exhibited a pronociceptive effect and did not change the antinociceptive effect of Ang II. The adenosine A2A receptor agonist PD-125944 (DPMA; 0.1, 0.5 and 1 mg/kg) showed pronounced antinociceptive effect. Ang II (0.1 microg/mouse) did not significantly influence the antinociceptive effect of DPMA (0.1 mg/kg). The A2A receptor antagonist 3,7-dimethyl-1-propargilxanthine (DMPX; 0.1 mg/kg) had no effect on the number of writhes and did not influence the effect of Ang II. These data indicate that the antinociceptive effect of Ang II interacts with that produced by adenosine A1 receptor agonist.

Assignment schemes for replicated services in Jini

This paper introduces and compares different schemes for assignment of replicated services in Jini - an object-oriented middleware architecture for network-centric computing. Each client in Jini has to be assigned a service selected from the pool of available services, which have joined the Jini federation and registered with the lookup service. Both early and delayed assignments are considered as basic options in our evaluation. The information for the system load can be collected at four different levels of detail in order to be used in the process of assignment decisions. In our analysis, we concentrate on the scenario where the requests for service generated by the clients follow independent user-initiated or machine-initiated transactions. The performance evaluation of the assignment schemes follows the queuing systems methodology. The comparisons are done with regard to the mean residence time of the clients in the system as well as the control overhead imposed by the assignment schemes. A case study of the scheme using the lowest information level proves the effectiveness, applicability and limitations of the delayed assignment in comparison to the early one. These results are a first step towards developing a methodology for building large-scale applications for Jini-based distributed systems.

Modeling and Implementation of Bus Rapid Transit corridor based on Traffic Prioritization and Automatic Location

In many cities facts defining conditions for very high concentration of functions and population make transport difficult. The proposed solution is an Automated Vehicle Location (AVL) and prioritization system for mass urban transport buses, and priority vehicles, through a Bus Rapid Transit (BRT) corridor. The solution consists of a detection sub-system, with a bus component, using transmitter, and a receiver placed on the traffic lights, the traffic lights, and a control center. We aim in minimizing the waiting time on traffic lights, and thus the waste of time on traveling. Such system is a useful instrument for any mass urban transport system.

Modeling and Implementation of Bus Rapid Transit corridor based on isolated or coordinated Traffic Prioritization and Automatic Location

In many cities facts defining conditions for very high concentration of functions and population make transport difficult. The proposed solutions are Automated Vehicle Location (AVL) and prioritization systems for mass urban transport buses, and priority vehicles, through a Bus Rapid Transit (BRT) corridor. Two solutions presented, which consist of a detection sub-system, with a bus component, using transmitter, and a receiver placed on the traffic lights, in the case of isolated system and an additional control center, in the case of the integrated / coordinated system. The functionality is described, and it is also presented as architecture the solution of an integrated bus priority management GPS system. In both cases we aim in minimizing the waiting time on traffic lights, and thus the waste of time on traveling. Such system is a useful instrument for any mass urban transport system.

Numerical Solution of Cloud Servicing Models

This paper presents a method for numerical solution of Markov-chain based models of dynamic load balancing schemes for cloud clusters. These schemes were presented in detail in earlier publications. Here we are describing the fast converging iterative solution of a class of such models. The numerical solution of the dynamic load-balancing models by computer solvers proved to be problematic if not applicable due to its computational instability. Other numerical methods available for solving Markov chains relay on constant transition rates or at least on rates that are not depending on the state probabilities. The proposed method combines analytical approach with the simple computations based on electronic tables and gives a solution in just a few iteration steps. It is designed especially for Markov chains in which transition rates are functions of the steady-state probabilities -- and that is the case of most dynamic load balancing schemes. The simplicity of this numerical method allows to compute the parameters for vast modeling space thus providing a broad picture of cloud servers performance.

A Java Task Execution Manager for Commodity Grids

Remote execution of applications is used in many distributed systems, including grid systems, volunteer computing networks, peer-to-peer networks, etc. In this paper we describe a software module, which executes Java code remotely. It runs on the remote host and makes its resources available for executing applications on them. Its basic characteristics are its flexibility, extensibility and minimal requirements to the host it runs on. This module executes arbitrary Java applications, both in the form of Java .class files or archived in .jar files. It may execute not only main methods, but also any other public method in the program. The input to the executed method, as well as the output, unlike many other similar components, may be not only based on files, but also values of arbitrary type.