This study was conducted to estimate the prevalence of Salmonella spp. and their antimicrobial susceptibilities on poultry and swine farms, sampled in 2 regions in Central Vietnam. A total of 67 poultry farms and 46 swine farms were sampled in a period of 5 months (from September 2012 to January 2013). Salmonella spp. was prevalent in 46.3% and 71.7% of poultry and swine farms, respectively. Altogether, 99 non-typhoidal Salmonella were isolated and the most common serovars were Salmonella Weltevreden (19%), followed by Salmonella Typhimurium (12%) and Salmonella 4,[5],12:i:- (11%). Overall, 71 of 99 (72%) Salmonella isolates were resistant to at least one of the 14 antimicrobial agents tested. Both in poultry and swine farms, high levels of resistance were observed for ampicillin, chloramphenicol, ciprofloxacin, sulphamethoxazole and tetracycline. The presence of Salmonella isolates from poultry and swine farms which were resistant to different classes of antimicrobials suggests that alternative control measures to antimicrobials should be implemented. Moreover, an effective policy should be promoted to encourage a prudent use of these agents in animal farming in Vietnam.

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A dual-band circularly-polarised antenna implemented on a single substrate is proposed for Ku-band satellite communication. A microstripfed Spidron fractal patch is utilised to achieve dual-band resonance and circular polarisation. The proposed antenna, with dimensions of 50 × 50 × 1.52 mm 3 , has also been fabricated and tested. The measured −10 dB reflection bandwidths are 8.7% (11.44-12.48 GHz) and 6.6% (13.47-14.39 GHz), exhibiting a small resonant frequency ratio of 1.15. The 3 dB axial ratio bandwidths for the lower band and the upper band are 2.96 and 1.68%, respectively.

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Abstract-In this paper, the design of a single-feed triple-band circularly polarized Spidron fractal slot antenna is presented. The proposed antenna is composed of a Spidron fractal slot, a Z-shaped slit, and two L-shaped slits to realize triple-band circular polarization operation. A simple 50 Ω microstrip line is utilized to feed the proposed antenna. A conducting reflector is also used to reduce back radiation, thereby enhancing the forward antenna gain. The proposed antenna has total dimensions of 40.7 mm×40.7 mm×18.52 mm (0.42λ×0.42λ× 0.19λ) and was fabricated and tested. The experimental results show that the proposed antenna has −10 dB reflection coefficient bandwidths from 2.76 GHz to 3.13 GHz and from 3.56 GHz to 6.22 GHz. The measured 3 dB axial ratio bandwidths are 2.28% (3.04-3.11 GHz) for the lower band, 7.15% (4.18-4.49 GHz) for the middle band, and 2.6% (4.93-5.06 GHz) for the upper band. The peak gains within the −10 dB reflection coefficient bandwidths are 3.41 dBic and 6.29 dBic, respectively.