Directional excitation of sound in an aperiodic finite baffle system is analyzed using a method developed earlier in electrostatics. The solution to the corresponding boundary value problem is obtained in the spatial-frequency domain. The acoustic pressure and normal particle velocity distribution in acoustic media can be easily computed by the inverse Fourier transform from their spatial spectra on the baffle plane. The presented method can be used for linear acoustic phased arrays modeling with finite element size and inter-element interactions taken into account. Some illustrative numerical examples presenting the far-field radiation pattern and wave-beam steering are given.
Florfenicol is a broad-spectrum bacteriostatic antibiotic commonly used for the treatment of systemic infections in farm animals. The aim of this study was to determine the effect of florfenicol on the percentage of T lymphocytes (CD3+, CD4+, CD8+, TCRgd+ cells) and B lymphocytes (Bu-1+ cells) and on total serum anti - sheep red blood cell (SRBC) haemagglutinin titer in the peripheral blood of SRBC–immunized broiler chickens. The study included three groups of broiler chickens differentiated by weight (0.5, 1.2, 2.4 kg). Florfenicol was administered orally at a dose of 30 mg/kg. The drug was administered eight times at 24 h intervals. The chickens were immunized with SRBC 24 h after administration of the third dose of florfenicol. Florfenicol increased the percentage of CD3+ blood lymphocytes with a corresponding decrease in the percentage of B lymphocytes in birds weighing 0.5 and 2.4 kg. Florfenicol reduced the production of total anti SRBC-haemagglutinins on day 5 after antigen injection in all three body weight groups of the broiler chickens. In conclusion, florfenicol exerted a modulating effect on the immune response of the birds and this should be taken into consideration when using this antibiotic for certain indications.