Economies of Pond Size for Hybrid Striped Bass Growout1

The objective of this study was to evaluate the relationship of pond size and hybrid striped bass growout profitability as an alternative source of farm income in the Mid-Atlantic region. A dynamic, whole farm, Montdarlo capital budgeting simulation model (AQUASIM) and stochastic dominance with respect to a function technique were used to analyze the economics of hybrid striped bass growout from phase II to market production stage for eight farms categorized by pond sizes. Three scenarios are assumed to examine the effects of pond-size dependent changes in feed conversion efficiency and fingerling survival rates on discounted after-tax net present values and probabilities of economic survival and success. Optimal pond sizes were found to be in the 2.5 acre to 10 acre range.     

The effects of straw disposal and depth of cultivation on the growth, nutrient uptake and yield of winter wheat on a clay and a silt soil

Abstract. Experiments were conducted for one year on two different soil types. On a clay soil straw was either (a) burnt, (b) baled leaving the stubble, or (c) chopped and spread. The soil was tine cultivated to depths of 5, 10 or 15 cm or ploughed to 20 or 30 cm before winter wheat was sown conventionally. In addition, a direct-drilled crop was sown after each straw treatment. On a silt loam soil the direct-drilled, tine cultivated to 15 cm and ploughed to 30 cm treatments following burning or chopping and spreading straw were repeated.
Tine cultivation incorporated less straw than ploughing, decreased plant establishment and early growth but did not decrease yield. Direct-drilling through chopped straw decreased yield on the silt loam but not on the clay soil. Short straw (< 5 cm) was easier to incorporate than longer straw. Ploughing was the most efficient method of straw incorporation because it inverts soil. Early effects on crop growth and nutrient uptake following straw incorporation were transient and associated with large amounts of straw in the seeded layer of soil.     

Software

Two principal themes are observed in software development, both aimed at improving the productivity of developing and maintaining new applications. The first is to provide increasingly rich system programming function in order to handle the details of managing hardware resources. The second is to provide application development facilities with logical structures and building blocks more closely aligned with the logic of the application itself. An additional challenge is to provide these in a way that will allow continued enhancement of existing software.     

日光温室内反光膜补光的实践与理论探析

试验结果表明 ,温室后墙悬挂反光膜进行补光后 ,对温室内测定点处最大光照度值无影响 ,但平均提高测定点处水平光照度值 15 4 8% ;温室内凌晨时气温、地温、墙温和被反光膜遮掩处墙温分别比对照温室低 1 1℃、1 5℃、0 9℃和 1 8℃ ,但正午时分别比对照温室高 1 6℃、1 4℃、0 3℃和低 11 4℃。温室经济产量增加 7 4 % ,当期经济效益增加 2 1元 /m2 。     

不同栽培模式及施氮量对半旱地冬小麦氮素累积及分配的影响

【目的】研究不同栽培模式和施氮量对半旱地栽培条件下冬小麦-夏玉米轮作体系中冬小麦地上部氮素累积、分配及利用效率的影响。【方法】在陕西关中地区进行了田间试验,以常规栽培为对照,比较了补灌、覆草和垄沟等栽培模式及0,120,240 kg/hm2施氮水平,对冬小麦连续2年(2004和2005年)不同生长期各部位氮素累积量的影响。【结果】在补灌模式下,2004和2005年成熟期冬小麦叶片和茎秆的氮素累积量较其他模式低,氮素分配率也较低,而籽粒的氮素分配率较高;施用氮肥显著增加了各生长时期冬小麦叶片、茎秆、颖壳和穗轴以及籽粒的氮素累积量,当氮肥施用量由120增加到240 kg/hm2时,除籽粒外,成熟期冬小麦叶片、茎秆、颖壳和穗轴的氮素残留量均随之明显增加。与不同栽培模式相比,施用氮肥对冬小麦不同器官中氮素分配的影响较小。随着氮肥施用量的增加,氮肥利用效率、氮肥农学效率和氮肥生理效率均呈降低趋势。在不同栽培模式中,连续2年补灌栽培模式下冬小麦的氮肥利用效率、氮肥农学效率以及氮肥生理效率均较高,而其他栽培模式下这3个指标年际间的变化较大。【结论】施用氮肥可显著增加冬小麦各生长时期不同器官的氮素累积量,但对氮素在不同器官中分配比例的影响较小;与施用氮肥相比,不同栽培模式对冬小麦氮素的累积、分布无明显影响;冬季补灌有利于提高冬小麦的氮素效率。     

Extrahepatic biliary tract surgery in the cat: a case series and review

Four cases of extrahepatic biliary tract surgery in the cat are described. The causes of the disease were inflammation of the gallbladder, distal common bile duct (CBD) or major duodenal papilla, and traumatic avulsion of the CBD. Bile peritonitis was present in two of the cats. Biliary enterostomy was performed in three cats, two of which were euthanased at five weeks and three months postsurgery; the third was alive at the time of writing, four months postsurgery. Cholecystectomy was curative in one cat. A literature review reveals high early mortality following biliary diversion, with only 50 per cent of cases surviving more than two weeks, and 23 per cent surviving more than six months. Surviving cats had repeated intermittent vomiting and anorexia that responded to antibiotics. No postoperative mortality was seen when biliary diversion was avoided. Whenever biliary enterostomy or temporary diversion methods are performed, a poorer prognosis should be offered due to the increased likelihood of postoperative complications and mortality.     

Total ear canal ablation in the cat: indications, morbidity and long-term survival

Fifty-two total ear canal ablation (TECA) procedures in 44 cats were reviewed. The indication for surgery was neoplasia in 41 per cent of the cats, 86 per cent of which had ceruminous gland adenocarcinoma. Chronic inflammatory or polypoid disease accounted for 50 per cent of surgical procedures. Postoperative complications included Horner's syndrome (42 per cent) and facial paralysis (56 per cent) and these were permanent in 14 per cent and 28 per cent of cases, respectively, with the rest resolving in the ensuing weeks or months. The higher incidence of Horner's syndrome and facial paralysis in the cat, compared to the dog, was attributed to greater fragility of the feline tympanic plexus and facial nerve. The median survival time of cats with ceruminous gland adenocarcinoma was 50-3 months, and did not differ significantly from that for inflammatory or polypoid disease. A potential prognostic indicator for this tumour was the mitotic index (MI): cases with MI < or = 2 survived significantly longer than those with MI > or = 3.