A high resistance against first-generation cephalosporins, ampicillin, amoxycillin-clavulanate and TMP-SMX which are the first-line antibiotics in childhood urinary tract infections was found. Carbapenem (meropenem, imipenem) resistance was not found in our center. Nitrofurantoin, aminoglycosides and cefixime can be recommended for empirical treatment in our hospital because of low resistance. Antibiotic treatment should be redecided according to in vitro antibiotic sensitivity results.

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In a previous study (Kaplan H, Seireg A., Int. J. Comput. Appl. Technol., 2000; 13(1=2): 25-41), the authors proposed a base isolation system for earthquake protection of structures. The system incorporates spherical supports for the base, a specially designed spring-cam system to keep the base rigidly supported under normal conditions and to allow it to move for the duration of the earthquake under the constraint of a spring with optimized sti ness characteristics. A single-degree-of-freedom structure was considered to investigate the feasibility of the concept. The simulation of the system response shows a 20 times reduction of the transmitted force as a result of using the proposed design in the considered case. This paper extends the previous study to the case of a 40-storey steel structure subjected to the Taft as well as El Centro earthquakes. A 7.5 and 6 times reduction of the maximum transmitted force was achieved for the considered disturbances, respectively, without any adverse e ects due to the tilting moment which is inherent in this type of base isolation.

ABSTRACT:A base-isolation system was developed for earthquake protection of low-rise structures. The system incorporates spherical supports for the base, a specially designed spring-cam system to keep the base supported under normal conditions, and moves for the duration of the earthquake under the constraint of a spring with optimized stiffness characteristics. The dynamic behaviour of a three-story concrete structure with and without the base isolation subjected to the Taft and El Centro earthquake loads was investigated. The results indicated that the absolute peak acceleration and displacement as well as shear forces decreased significantly with the application of a base isolation system, and it is possible to achieve 87 to 94% reduction in the maximum accelerations and transmitted forces. The movement of the base relative to the ground was less than 0.15 m in the optimized system, and the springs were not fully compressed at any time during application of the earthquake loads. The maximum induced vertical forces as a result of the spherical base support were found to be less than 1.5 % of the weight of the structure. Since the system performance is highly dependent on the rapid unlocking of the cams in the event of a seismic disturbance, careful consideration should be given to the optimal design of the spring-cam system.

SUMMARYThe study reported in this paper investigates the feasibility of developing an active base isolation system for the protection of bridges subjected to earthquakes. The proposed system incorporates spherical supports, cams and springs which can be optimally designed to minimize the transmissibility of the seismic disturbances to the bridge. The considered example shows that the proposed design is implementable and can provide an order of magnitude reduction in the maximum stress resulting from seismic waves acting on the bridge in the transverse or longitudinal direction.Since the system performance is highly dependent on the rapid unlocking of the cams in the event of a seismic disturbance, careful consideration should be given to the design of a reliable cam release control. This can be achieved by spring loading each cam such that it would be normally unlocked. A hydraulic actuator would be used to force it to rotate to the locking position under uid pressure which would be constantly maintained at the design level during normal conditions. The actuator would be equipped with a quick response release valve for rapidly releasing the pressure and consequently unlocking the cam as soon as an earthquake is detected.