Outbreaks of proliferative haemorrhagic enteropathy on two pig farms   总被引：2，自引：0，他引：2  

PK HOLYOAKE  RS CUTLER 《Australian veterinary journal》1995,72(7):253-256

SUMMARY Clinical signs of proliferative haemorrhagic enteropathy (PHE) including anaemia, dysentery and sudden death were observed in finisher pigs and young breeding stock on 2 farms. On farm A, PHE occurred 12 months after repopulation of the farm. Other outbreaks of PHE occurred after the withdrawal of therapeutic concentrations of in-feed antibacterial agents (farm A), or after monensin sodium (100 g/t) replaced olaquindox (100 g/t) in feed (farm B). The outbreaks, the possible sources of contamination and the role of antibacterial feed additives in the treatment and control of PHE are described.  相似文献   

Modeling lumber strength spatial variation using trend removal and kriging analyses     

Frank Lam  J. D. Barrett 《Wood Science and Technology》1992,26(5):369-381

Summary The techniques of kriging and trend removal analysis for modeling the strength properties of lumber have been discussed. Using these techniques, the within member compressive strengths of 38 mm × 89 mm 2100f-1.8E and the within member tensile strengths of 38 mm × 89 mm No. 2 spruce-pine-fir lumber have been modeled. The suitability of these techniques to model the strength properties of lumber has been evaluated by comparing the kriged compressive and tensile strength data to baseline experimentally collected compressive strength data and simulated tensile strength data, respectively. Comparisons of the results of statistical analyses of the baseline data and the kriged data show good agreement. The use of kriging and trend removal techniques to generate strength values in simulation studies for finite element analyses of wood structures is judged to be effective.  相似文献   

Modified algorithm to determine localized modulus of elasticity of lumber     

F. Lam  Prof. Dr. R. O. Foschi  Prof. Dr. J. D. Barrett  Technician Q. Y. He 《Wood Science and Technology》1993,27(2):81-94

Summary A procedure has been developed to determine the cut-off frequency in an algorithm to evaluate the localized modulus of elasticity (MOE) in lumber. MOE profiles have been artificially generated to serve as input for evaluation of the procedure. A noise component has also been added to the input record to test the robustness and accuracy of the procedure. Good agreement between program predictions and the known localized MOE values has been obtained. The efficiency of the procedure has also been tested using MOE profiles collected from experiments. The program performed efficiently and program predictions seemed reasonable.  相似文献   

Variation of tensile strength along the length of lumber     

F. Lam  E. Varo  -glu 《Wood Science and Technology》1991,25(6):449-458

Summary A model has been developed for the within member variation of tensile strengths parallel to grain in nominal 38 × 89 mm No. 2 Spruce-Pine-Fir lumber. Tensile strength data from two modulus of elasticity matched groups were considered. Model parameters obtained from data group 1 were used to generate tensile strength profiles of lumber 6.10 m long. Within member tensile strength cumulative probability distributions of the simulated data were evaluated by window analyses. The spatial correlation of the simulated data were evaluated by semivariogram and regression analyses. Good agreement was obtained between model predictions and test results of both groups.The authors gratefully acknowledge the support of the Canadian Forest Service and the technical assistance of Mr. H. Sue, Mr. B. Deacon and Dr. J. Cook for this study. The research was performed while the principal author was working at Forintek Canada Corp.  相似文献   

Structural characteristics of cell walls of kenaf (<Emphasis Type="Italic">Hibiscus cannabinus </Emphasis>L.) and fixation of carbon dioxide     

Thi Bach Tuyet Lam  Keko Hori  Kenji Iiyama 《Journal of Wood Science》2003,49(3):255-261

 Kenaf (Hibiscus cannabinus) plants are widely known for their contribution to the global and regional environment because of their ability to fix CO₂. On the other hand, some scientists have doubts about CO₂ fixation by kenaf and have misgivings about the effect of kenaf on the ecosystem. We have characterized the structural characteristics of cell walls of bast fibers, cores, roots, and leaves of kenaf during the maturation of plants and investigated the rate of photosynthesis. During maturation of the kenaf plant the cellulose (bast fiber 52–59%, core 44–46%) and lignin (bast fiber 9.3–13.2%, core 18.3–23.2%) contents increased significantly. The aromatic composition of the lignin of bast fiber was significantly different from that of the core lignin and of other plants. The lignin of bast fiber appears similar to pure syringyl lignin. Fixation of CO₂ by kenaf plants and their contribution to the global environment are discussed. A significatly high rate of photosynthesis of kenaf plants was observed compared to that of woody plants in Japan, but the amount of CO₂ fixation depends on the characteristics of the plantation. If the kenaf was planted in high density, about twice as much CO₂ was fixed as was fixed by trees in a tropical rain forest. Received: April 22, 2002 / Accepted: July 24, 2002 Acknowledgments This project was supported by the Science and Technology Agency (STA) fellowship of the Japan International Science and Technology Exchange Center (JISTEC), which has been successfully applied by Dr. Shuji Hosoya, Forestry and Forest Products Research Institute. We thank Dr. Toshio Sumizono and Mr. Masao Sakurai, Forestry and Forest Products Research Institute, for their kind help in determining the rate of photosynthesis and cultivating the kenaf plants, respectively. We also express our appreciation to Dr. Quang Hung Le, College of Agriculture and Forestry, Ho Chi Minh City, Vietnam for offering information about the cultivation of kenaf at Thu Duc District, Ho Chi Minh City.  相似文献   

Handedness of whip use by Australian Jockeys     

PK Knight  NA Hamilton 《Australian veterinary journal》2014,92(7):231-234

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Using a stand-level model to predict light absorption in stands with vertically and horizontally heterogeneous canopies     

David I Forrester  Rubén Guisasola  Xiaolu Tang  Axel T Albrecht  Tran Lam Dong  Guerric Ie Maire 《中国林学(英文版)》2014,1(3):158-176

Background： Forest ecosystem functioning is strongly influenced by the absorption of photosynthetically active radiation （APAR）, and therefore, accurate predictions of APAR are critical for many process-based forest growth models. The Lambert-Beer law can be applied to estimate APAR for simple homogeneous canopies composed of one layer, one species, and no canopy gaps. However, the vertical and horizontal structure of forest canopies is rarely homogeneous. Detailed tree-level models can account for this heterogeneity but these often have high input and computational demands and work on finer temporal and spatial resolutions than required by stand-level growth models. The aim of this study was to test a stand-level light absorption model that can estimate APAR by individual species in mixed-species and multi-layered stands with any degree of canopy openness including open-grown trees to closed canopies. Methods： The stand-level model was compared with a detailed tree-level model that has already been tested in mixed-species stands using empirical data. Both models were parameterised for five different forests, including a wide range of species compositions, species proportions, stand densities, crown architectures and canopy structures. Results： The stand-level model performed well in all stands except in the stand where extinction coefficients were unusually variable and it appears unlikely that APAR could be predicted in such stands using （tree- or stand-level） models that do not allow individuals of a given species to have different extinction coefficients, leaf-area density or analogous parameters. Conclusion： This model is parameterised with species-specific information about extinction coefficients and mean crown length, diameter, height and leaf area. It could be used to examine light dynamics in complex canopies and in stand-level growth models.  相似文献   

Morphological changes in carp epithelial cells infected with Aeromonas hydrophila   总被引：1，自引：0，他引：1  

K Y Leung  T M Lim  T J Lam  Y M Sin 《Journal of fish diseases》1996,19(2):167-174

The in vitro interaction of Aeromonas hydrophila with epithehoma papillosum cells of carp (EPC) was studied. All the virulent and type strains invaded and multiplied inside EPC cells. Morphological changes were induced by the virulent and type strains during the processes of invasion and intracellular replication. Among the virulent group, strain PPD134/91 required the shortest time (30 min post-infection) to induce cytopathic effects in the EPC monolayers. The EPC cells infected with PPD 134/91 became retracted and condensed, lost their attachment abilities, and eventually disintegrated. Confocal microscopy revealed that tubular structures measuring 0.77 ± 0.19 μm appeared to connect the retracted EPC cells. The cytopathic effect was attributed to the growing and metabolically active bacteria. Avirulent strains such as L37 did not multiply nor induce cytopathic effects in the EPC monolayers.  相似文献   

Pseudaboydins A and B: Novel Isobenzofuranone Derivatives from Marine Fungus Pseudallescheria boydii Associated with Starfish Acanthaster planci     

Wen-Jian Lan  Wei Liu  Wan-Ling Liang  Zeng Xu  Xiu Le  Jun Xu  Chi-Keung Lam  De-Po Yang  Hou-Jin Li  Lai-You Wang 《Marine drugs》2014,12(7):4188-4199

Two novel isobenzofuranone derivatives, pseudaboydins A (1) and B (2), along with five known compounds, including (R)-2-(2-hydroxypropan-2-yl)-2,3-dihydro-5-hydroxybenzofuran (3), (R)-2-(2-hydroxypropan-2-yl)-2,3-dihydro-5-methoxybenzofuran (4), 3,3′-dihydroxy-5,5′-dimethyldiphenyl ether (5), 3-(3-methoxy-5-methylphenoxy)-5-methylphenol (6) and (−)-regiolone (7), were isolated from the culture broth of the marine fungus, Pseudallescheria boydii, associated with the starfish, Acanthaster planci. Their structures were elucidated primarily based on NMR and MS data. The absolute configurations of 1–4 were determined by CD spectroscopy and single-crystal X-ray diffraction studies. The cytotoxic and antibacterial activities of 1–4 were evaluated. Pseudaboydin A (1) showed moderate cytotoxic activity against human nasopharyngeal carcinoma cell line HONE1, human nasopharyngeal carcinoma cell line SUNE1 and human glandular lung cancer cell line GLC82 with IC₅₀ values of 37.1, 46.5 and 87.2 μM, respectively.  相似文献   

The evolving story of the equine morbillivirus     

PK MURRAY 《Australian veterinary journal》1996,74(3):214-214

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