Pocono mesic till barrens in retreat: topography,fire and forest contagion effects

The Pocono mesic till barrens (PMTB) are a unique assemblage of fire-maintained shrub communities that support numerous rare species. Historically these barrens covered a large area in the vicinity of Long Pond, Pennsylvania, USA. However, due largely to regional fire suppression instituted in the early 1960s, over 70% of the area covered by barrens succeeded to fire-intolerant forest that does not support the rare species. We investigated the influence of forest proximity on barrens succession across three geomorphic types during periods of high fire frequency and fire suppression, testing the hypothesis that forest processes such as seed rain, shading, and detrital enrichment of soils enhances barrens succession through a contagion effect. Evidence of a forest contagion effect should be shown by increased rates of barrens succession with increasing proximity to the nearest forest edge. In order to detect a forest contagion effect, barrens persistence and barrens succession were modeled in proximity zones of 0-50 m, 50-100 m, 100-200 m, and greater than 200 m from the nearest forest edge. We used existing GIS data layers for fire, geomorphology, and vegetation distribution in 1938, 1963, and 1992. The layers were modified and overlain using ArcView software to determine persistence and succession rates for each unique combination of layers in each proximity zone from 1938 to 1963 (pre-fire suppression) and 1963 to 1992 (post-fire suppression). ANCOVA results indicate that proximity to the nearest forest edge significantly affected barrens persistence rates in both time periods, but succession rates were significantly affected in 1938 to 1963 only. Twenty-eight percent of the 1938 barrens succeeded to forest by 1963; 56% of the 1963 barrens became forest by 1992. Results support previous findings that barrens persistence is enhanced by increased fire frequency, and that barrens persist longer where they overlie flat glacial till than on other geomorphology types.     

Moving toward a more physiological model: application of mucin to refine the in vitro digestion/Caco-2 cell culture system

The objective of this study was to determine if a combination of commercially available mucin and an 8 microm microporous membrane insert can be used to replace the 15 kDa molecular weight cutoff (MWCO) dialysis membrane used in an established in vitro digestion/Caco-2 cell culture system. Although the current model with the 15 kDa membrane correlates well with human studies, use of mucin may improve the system as the mucus layer is suspected to play a physiological role in Fe absorption. Use of mucin may also enable more complete assessment of iron bioavailability from large molecular weight forms of Fe such as heme and ferritin Fe. A range of foods or Fe (i.e., FeCl(3) +/- ascorbic acid, cooked beef, red bean, white bean, soybean, horse spleen ferritin and plant-type ferritin) were subjected to in vitro digestion. In the presence of mucin, significantly more Fe was taken up from the heme Fe (86%) and ferritin (91%) samples and significantly less Fe was taken up from the white bean samples ( approximately 70%) relative to the 15 kDa membrane. The results indicated that the forms of iron interact with mucin. The mucus layer has a significant effect on Fe uptake. Further refinement and characterization of the mucin method is needed before it can be deemed to be a suitable replacement for the dialysis membrane.     

南疆巴旦杏园朝鲜球坚蚧不同发育期的防治措施研究

为了探寻不同发育期朝鲜球坚蚧的有效防治新措施,根据朝鲜球坚蚧不同发育阶段的形态特征和生物学习性,对不同龄期的若虫采取刮皮涂干、树干注射和常规喷雾等措施进行防治.试验结果表明;在施药方法上,刮皮涂干和常规喷雾是最为适用的;在药效方面,在1龄若虫期喷雾施用的几种药剂中醋盐合剂对1龄若虫的喷洒防效达到了90%以上.通过施用脱叶剂处理叶片的方法来防治2龄若虫,试验所设3种浓度的脱叶剂均能间接起到防治作用,其效果均达到了95%以上.在3龄若虫期喷雾施用的几种药剂中95%酒精合剂的喷洒防效达到了90%以上.涂干防治3龄若虫期供试的几种药剂中,20%吡虫啉可溶性液剂1∶10的稀释液防效达到了90%以上.     

Surgical treatment of tarsal sheath effusion associated with an exostosis on the calcaneus of a horse

A 2-year-old Thoroughbred colt was referred for evaluation of effusion within the tarsal sheath and associated lameness of the right hind limb. Conservative treatment consisting of needle aspiration and pressure bandaging had been unsuccessful. Radiography of the right tarsus revealed proliferative periosteal reaction along the distal caudal border of the sustentaculum tali and medial aspect of the calcaneus. The owners elected conservative treatment, using a local injection of corticosteroid and pressure bandaging the tarsus. Five months later, the severity of the effusion and lameness had increased. Radiography revealed increased reactive bone along the sustentaculum tali and mineralization of the plantar tarsal ligament and tarsal sheath. Surgical exploration revealed fibrous adhesions between the medial aspect of the calcaneus and the flexor tendon and associated soft tissue mineralization. The adhesions were broken down and the reactive bone along the calcaneus was removed. The mineralized soft tissue within the tarsal sheath was excised. Five months after surgery, the horse was sound at the trot, with only minimal tarsal sheath effusion. The response to treatment for tarsal sheath effusion and lameness caused by bony changes of the sustentaculum tali is often unsatisfactory. After responding poorly to conservative treatment, the horse in this report had a favorable outcome to the surgical intervention of this condition.     

Evidence for the enhanced biodegradation of napropamide in soil

In laboratory incubations, the time to 50% loss of napropamide was approximately 60; 21 and 8 days in soil treated for the first, second and third time respectively. In a survey of soils from commercial fields, there was evidence that enhanced biodegradation of the compound had been induced by normal field applications—in some soils by a single previous treatment. Confirmation of the observations of rapid rates of loss in pre-treated soil was obtained in experiments with three formulations of napropamide. The rate of degradation in enhanced soils was unaffected by treatment of the soils with the antifungal antibiotic cycloheximide, but was inhibited by the antibacterial antibiotic chloramphenicol. Mixed bacterial cultures able to degrade the herbicide were obtained from three rapid-degrading soils by enrichment culture. Isolates from two of them were able to degrade the herbicide in pure culture. These bacteria have, as yet, not been characterised.     

Elective cesarean section in mares: eight cases (1980-1989)

From 1980 to 1989, 8 cesarean sections were performed on an elective basis in 5 mares. Four mares had partially obstructed pelvic canals; 2 of these mares had previously lost foals because of dystocia. Cervical adhesions that might obstruct passage of the fetus through the pelvic canal was suspected in the fifth mare. Cesarean section was performed prior to mares entering the first stage of labor. Readiness for birth was estimated by development of the mare's mammary gland and the presence of colostrum in the udder. A ventral midline celiotomy provided excellent exposure and healed without complications in all instances. Eight viable foals were produced. One foal developed bacterial pneumonia and septicemia after surgery and died. Follow-up evaluation of the 7 foals discharged from the hospital failed to reveal complications associated with elective cesarean section. All mares survived the procedure. Fetal membranes were retained for up to 72 hours following surgery; however, systemic complications secondary to retained placenta did not develop. Three mares were bred subsequent to elective cesarean sections, with each mare conceiving the year following surgery. Three foals were produced by 1 mare and 2 foals have been produced by another mare by elective cesarean sections.