Urgency Index Ratios: a Simple Tool for Forest Management     

GRAY  S. J.; PRICE  COLIN 《Forestry》1990,63(2):161-175

Traditional forest economics deals with regularly-ordered activities.For many reasons, however, choices must often be made amongconflicting operational priorities. In these circumstances,maximizing net discounted revenue per hectare does not maximizeglobal profit. Priorities for action should be chosen in orderof urgency index ratio, defined as the cost of delaying an operationdivided by the units of limited resource needed to undertakethe operation. Forest managers tend to use informal and sometimesconflicting rules to assign priorities among uses of limitedresources. These priorities often differ from those indicatedby urgency index ratio. Urgency index ratio can be determinedby simple calculations based on readily-available data. Theconcept can be extended to include multiple constraints.  相似文献   

Mid-storage and pre-sowing seed treatments for lettuce and carrot     

Dolly Pan  R.N. Basu 《Scientia Horticulturae》1985,25(1):11-19

Mid-storage hydration-dehydration treatments with medium-vigour lettuce seed very effectively reduced physiological deterioration in storage and ultimately showed better field emergence and final yield. Soaking-drying treatment of high-vigour lettuce seed was not effective. Pre-sowing treatment of medium-vigour lettuce seed, though less effective than mid-storage treatment, gave better field performance, but high-vigour seed did not benefit from the treatment. For carrot, both mid-storage and pre-sowing seed treatments proved beneficial, with the former showing better performance than the latter. Unlike lettuce, well-preserved carrot seed responded positively to the pre-sowing treatment.  相似文献   

Asymmetric illumination contrast: a method of image formation for video light microscopy   总被引：4，自引：0，他引：4  

B Kachar 《Science (New York, N.Y.)》1985,227(4688):766-768

Images with high resolution and exceptionally broad gray scale can be obtained by the application of video contrast enhancement to an optimized procedure for imaging transparent objects with oblique rays of illumination. This technique is simple to set up. A conventional microscope with a light source whose position can be adjusted and a video camera with controls for gain and black level are the only essential components. Features such as high resolution, optical sectioning, control of contrast, and operation under low light intensity make this technique preferable, in several instances, to currently used video microscopy techniques.  相似文献   

In vitro studies of haemolysis by Leptospira interrogans serovars pomona and ballum   总被引：2，自引：0，他引：2  

J C Thompson  R B Marshall 《Veterinary microbiology》1986,11(3):285-292

Washed and unwashed red blood cells (RBC) from young calves, adult cattle, hamsters and humans were incubated with Leptospira interrogans serovars pomona and ballum. Washed cells suspended in saline were always haemolysed while unwashed cells and those which were washed and resuspended in plasma were never haemolysed, despite the presence of large numbers of organisms within the culture supernatant. Pomona produced greater haemolysis of cattle and human RBC than did ballum, but with hamster RBC ballum produced greater haemolysis than did pomona. A group of 6- to 9-month-old cattle infected with pomona showed no signs of clinical disease and RBC taken from them before infection and during the development of antibodies to pomona were haemolysed by pomona only after the cells were washed. Plasma therefore appears to have a protective function. This in vitro protective function of plasma even extended to plasma from young seronegative calves.  相似文献   

The extent of genetic diversity among Vanilla species: Comparative results for RAPD and ISSR     

Praveen C. Verma  Debasis Chakrabarty  Satya Narayan Jena  Devesh K. Mishra  Pradhyumna K. Singh  Samir V. Sawant  Rakesh Tuli 《Industrial Crops and Products》2009,29(2-3):581-589

Vanilla is a large genus of about 110 species in the orchid family (Orchidaceae), including the species Vanilla planifolia from which commercial vanilla flavoring is derived. Since most species of vanilla are considered rare and endangered there is an urgent need to conserve them through genetic analysis and propagation/conservation studies on this crop.The present study investigated the genetic diversity among nine leafy- and leaf-less Vanilla species employing 30 decamer RAPD primers and 10 ISSR primers. The species under study were diverse and displayed a range of variability (0–66% and 0–81% for RAPD and ISSR, respectively). A total of 154 RAPD polymorphic markers (83.24%, h = 0.378) and 93 ISSR polymorphic markers (86.11%, h = 0.363) were used to generate a genetic similarity matrix followed by the cluster analysis. Specific groupings were revealed by each cluster analysis with slight variation between two different markers. Among the nine species studied, V. planifolia, Vanilla aphylla and Vanilla tahitensis revealed very low level of variation within their collections, thus indicating a narrow genetic base. The large genetic distance of Vanilla andamanica from other species suggests its different origin. A close genetic affinity was observed between the pairs V. planifolia, V. tahitensis and Vanilla albida, V. aphylla. These are the first comparative results for RAPD and ISSR reporting inter-relationship among nine cultivated, wild and hybrid Vanilla species.  相似文献   

A ROLLER BOTTLE TISSUE CULTURE SYSTEM     

Shaw DT  Kingsland LC  Brues AM 《Science (New York, N.Y.)》1940,91(2354):148-149

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Neuerungen der Schädlingsbekämpfung     

H. 《Journal of pest science》1940,16(6):69-71

Ohne Zusammenfassung  相似文献   

Vitamins in Canine Metabolism     

H. E. Robinson  L. D. Frederick 《Canadian journal of veterinary research》1941,5(10):288-291

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THREE CASES OF MALE INFERTILITY     

W. L. Hindmarsh  B.V.Sc  M.R.C.V.S.  D.V.H. 《Australian veterinary journal》1941,17(1):21-23

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Ein starkes Auftreten des Ampferblattk?fers     

Fr. 《Journal of pest science》1942,18(11):131

Ohne Zusammenfassung  相似文献