7 research outputs found
Epidemiological study on some environmental and management parameters affecting on WSD occurrence in Fenneropenaeus indicus and Penaeus vannamei
Get PDFFor the first time white spot disease (WSD) was reported in shrimp farms of khoozestan province, in southwest of IRAN in 2002. Then in 2005 the neighbor province, boushehr, was contaminated. In 2008 WSD outbreak reported in sistan-bloochestan province in southeast of Iran. In 2015 all of southern shrimp farms of country except Hormozgan, the middle southern province, which has remained free of WSD, are being contaminated. White Spot disease suspended shrimp culture in thousands hectares of shrimp farms. Considering that white spot disease has not been observed in Hormozgan province yet, the question is; to what extent environmental and management factors participated in preventing WSD outbreak or cause WSD outbreak. In this study (20102012), the effects of environmental factors and management, stressors that decrease immune system function of shrimp are discussed. In addition, the role of pathogen as the main factor of outbreak is discussed. The goal of this study is to define environmental parameters and management practices associates with outbreak of white spot disease in affected provinces and discover reasons of being Hormozgan province free of this disease. In this study the role of the local environmental factors and management practice stressors in susceptibility to WSD was determine. Both the effects of environmental factors in water of ponds including total ammonia, nitrogen, dissolved oxygen, pH, salinity, transparency, and temperature and management issues related to biosecurity are studied. There were overlaps on physical and chemical parameter values obtained in clear areas with contaminated areas .Results of the data analysis suggest that lack of association with WSD incidence was 7 times greater than WSD incidence despite of disease outbreak in sistan-bloochestan province, so other sources of white spot disease virus incidence was suspected in affected areas. Histopathological examinations and polymerase chain reaction (PCR) tests during project performance did not reveal white spot disease virus evidences in post larvae examined from khoozestan province stocked in farms but disease outbreak was happened in that farms , so we suspected to management practice include feed , pond preparation and carrier of disease. Recorded values of temperature and salinity in some months during inspection in Hormozgan province specified stressful condition that may lead to WSD outbreak, however the disease did not appear. Therefore the hypothesis that the water physical and chemical conditions are reasons to prevent disease outbreak in Hormozgan province is being rejected. The policy of Hormozgan’s fishery authorities, to replaced Fenneropenaeus indicus with specific pathogen free Litopenaeus vannamei, that is more resistant to some of diseases, before incidence of WSD in farms and to before being endemic in the Hormozgan province, made an advantage compare to affected southern provinces that introduced Litopenaeus vannamei after WSD prevalence to their farms. However it does not guarantee to maintain current trend of being Hormozgan province farms free of white spot disease. Therefore establishing the principals of biosecurity are strongly emphasized. Strategies taken by the proficient authorities in preparation of SPF shrimp broodstock can be the most important factor in preventing WSD. Regarding biosecurity principals purchased feed must be free of shrimp head powder. Construction the new shrimp farms should be as far as it could be away from contaminated areas
Effect of Fe and Zn Micro Nutrients on Yield and Yield Components of Pimpinella anisum L.
No full textThe higher levels of essential elements in soil may be caused in optimum yields and crop quality. So it seems to be necessary to examine different levels of nutrients like Fe and Zn on plants and their productivity. To evaluate effects of iron and zinc application on yield and yield components of Pimpinella anisum an experiment was conducted at the research farm of Urmia University in 2009. Treatments, iron application (0, 0.2, 0.4 and 0.6%) and zinc (0, 0.2, 0.4 and 0.6%), were arranged as factorial based on randomized complete block design with 3 replications. Results showed the significant effect of interaction between iron and zinc on the number of seed in per plant,1000 seed weight, biomass yield, seed yield and harvest index (HI). The maximum value of the 1000 seed weight (2.22 g) was obtained from 0% of Fe and 0.2% of Zn, whereas the minimum value of the 1000 seed weight (1.92 g) belonged to 2% of iron and 0% of zinc. The highest number of seed per plant (762), maximum value of biomass yield (2652 kg/ha) and highest of seed yield (1372 kg/ha) were obtained from 0.6 and 0.4 percent of Fe and Zn and the lowest number of seed per plant (272), maximum value of biomass yield (716 kg/ha) and highest of seed yield (470 kg/ha) were obtained from 0 and 0.6 percent of Fe and Zn, respectively. The highest HI (66.18) was obtained at control treatment and the lowest one (46.67) at both 0.4 percent of Fe and Zn. The essential oil percent increase in average values of Fe and Zn spraying. But accumulation of Fe and Zn were the maximum in higher levels of spraying
FREE VIBRATION ANALYSIS OF TRANSVERSE ISOTROPIC THICK RECTANGULAR PLATES ON TWO-PARAMETER PASTERNAK FOUNDATION
No full textIn this research, an exact solution for free vibration analysis of thick transversely isotropic simply supported rectangular plates on the Pasternak foundation was proposed using the displacement potential function method. By means of the proposed displacement potential functions for dynamic problems by
Eskandari-Ghadi, the differential governing equations in terms of displacements
were converted into two linear partial differential \ equations of second and
forth order. These differential equations were solved based on the separation
of variables \ method and satisfying exact boundary conditions. In order to
validate the \ results, the obtained \ results were \ compared \ with \ other \ available analytical \ works for isotropic and transversely isotropic plates, and it
indicated remarkable agreement. Having no simplifying assumptions for the
strain or stress distribution in the plate thickness, the obtained results in
this paper were applicable to any arbitrary plate thickness with no limitation
on its thickness ratio such as thin, moderately thick, and thick plates. Thus,
the obtained results of the present work can be used as a benchmark solution
for other analytical and numerical studies. To investigate the effect of various parameters on the vibrational plate response, the precise non-dimensional frequencies were obtained in different range of thickness ratios, aspect ratios, elastic foundation coefficients, and mechanical characteristics of plates. It was observed that with increasing thickness ratio and aspect ratio of the plate, the non-dimensional natural frequencies of plate decreased and increased, respectively. In addition, comparative results of isotropic and transversely isotropic plates showed that shear modulus in transverse direction would have significant influence on the vibrational behavior of rectangular plates. It was shown that when the value of the thickness ratio increased, the sensitivity of non-dimensional frequency response to values of foundation stiffness coefficients decreased. In addition, it can be conducted that the effect of the shearing layer of elastic foundation coefficient value increased by increasing the thickness ratios of plates
Evaluation of anti-leishmanial effects of killed Leishmania vaccine with BCG adjuvant in BALB/c mice infected with Leishmania major MRHO/IR/75/ER
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