Postcards from the past: charting the landscape-scale conversion of tropical Australian savanna to closed forest during the 20th century

Repeated sequences of digitised and geo-referenced historical aerial photography provide a powerful means of understanding landscape change. We use this method to demonstrate a landscape wide expansion of closed forest (42% increase in total coverage) in the Australian monsoon tropics over the past five decades. Retrospective habitat suitability models (HSI) of closed forest derived using four landscape measures (drainage distance, slope angle, aspect and elevation) for imagery taken in 1947 correctly forecast the subsequent spatial distribution of the expansion, with topographic fire protection primarily determining the closed-forest distribution. The dynamics of the closed forest-savanna boundary were predicted accurately by generalised linear models, with closed-forest expansion in fire-protected sites along forest edges and regression in the more fire-prone areas. Two factors may plausibly explain the expansion of closed forests. First, eco-ethnographic records stress the skilful use of fire by Aboriginal people in protecting isolated and locally resource-rich closed-forest patches. Second, the recent global increase in atmospheric CO₂ may be changing the competitive balance between savanna and forest by enabling C₃ trees to grow fast enough to escape the fire trap presented by flammable C₄ grasses.     

Microvascular Free Tissue Transfer: Results in 57 Consecutive Cases

Objective —To evaluate the outcomes and complications in a consecutive series of animals undergoing microvascular reconstructive procedures at two veterinary institutions. Study Design—Retrospective study. Animals or Sample Population—A total of 44 client-owned dogs and one red-necked wallaby. Methods —The medical records of all animals undergoing reconstructive microsurgical procedures at the Western College of Veterinary Medicine and Michigan State University were reviewed. Microvascular flap survival and related complications were described. Statistical analysis was performed to determine the significance of relationships between operative factors and outcome. Results —A total of 57 microvascular procedures were performed on 55 animals. Reconstruction was required after trauma in 42 animals, after ablative cancer surgery in 11 animals and for correction of congenital tissue aplasia in 1 animal. Donor tissues included the superficial cervical cutaneous, medial saphenous fasciocutaneous or musculofasciocutaneous, caudal superficial epigastric cutaneous, trapezius muscle or musculocutaneous, caudal sartorius muscle, latissimus dorsi muscle or musculocutaneous, cranial abdominal myoperitoneal, carpal footpad, digital footpad, and vascularized ulnar bone flaps. A total of 53 of 57 flaps (93%) survived. There was a significant relationship between flap failure and level of assistant surgeon experience (P < .05). Latissimus dorsi flaps were significantly more likely to fail when compared with pooled data from all other flap types (P < .01). Conclusions —The success of microvascular tissue transfer in this case series compares favorably with those reported in human reconstructive microsurgery. Both the primary and assistant surgeon should be practiced in microsurgical technique. Failure of latissimus dorsi flaps was not likely caused by an inherently deficient flap design, but was more likely attributed to the location and severity of trauma at the recipient site, the difficulty in isolating suitable recipient vessels for anastomosis or the absence of a trained assistant surgeon during these procedures. Clinical Relevance —This retrospective study documents the successful application of microvascular technique in a series of clinical cases requiring tissue reconstruction.     

ESTIMATION OF BLADDER VOLUME USING ULTRASONOGRAPHIC DETERMINATION OF CROSS-SECTIONAL AREAS AND LINEAR MEASUREMENTS

The purpose of this study was to determine if ultrasonographic measurement of multiple cross-sectional areas combined with linear dimensions of the bladder could be used as a method of estimating bladder volume in the dog, and, if so, to compare the accuracy of this estimation with that described previously using linear measurements alone. Fifty-two live dogs undergoing investigation for urological disease and 37 fresh canine cadavers were used for bladder volume determination. Maximal length, depth, width, and area were measured from the maximal longitudinal and transverse sonograms in each living animal. In cadavers, the cross-sectional area of the longitudinal section of the bladder was measured at one centimeter intervals, and the measurements were summed. Based on sequential partial regression analysis, the cross-sectional area of the longitudinal section of the bladder and length were the best predictors of actual bladder volume in living animals. However, based on the cadaver experiment, the best predictor of actual bladder volume was summed parasagittal area alone, and, in cadavers, this was a much better predictor of actual bladder volume than the combination of the cross-sectional area of the longitudinal section of the bladder and length. The formula derived in living dogs using the corss-sectional area of the longitudinal section of the bladder and length gave a less accurate estimation of bladder volume than a previously published formula where only linear measurements were used.     

A fluoroscopic study of the position and action of different bits in the horse's mouth

Fluoroscopy was used to visualize the position and movements of different types of bits within the horse's oral cavity. The jointed eggbutt snaffle normally lay between the tongue and palate with the joint hanging down toward the incisor teeth. By arching and elevating the tongue the horse was able to raise the mouthpiece between the cheekteeth. The jointed mouthpiece was suspended in a more horizontal position when keepers were used with a cheek snaffle to fix the position of the bit rings relative to the cheekpieces of the bridle. In addition, the mobility of the bit within the oral cavity was reduced by using keepers. Similarly less intra-oral movement was observed in bits with an unjointed mouthpiece.The Dr. Bristol bit, which has two joints connected by an angled plate, could be attached to the bridle in two ways so that the plate lay either parallel to the tongue and palate or perpendicular to them. This would be expected to have a marked effect on the severity of action of the bit. The high tongue port of the Hannoverian pelham pressed against the palate when the reins were used, causing considerable discomfort.     

Bilateral laryngeal paralysis in the horse

Four two-year-old Thoroughbreds suffered an acute gastrointestinal illness shortly after dosing with mineral oil which was thought to have been contaminated with an organophosphate compound. Three weeks later all four were noted to be dyspnoeic and endoscopic examination showed that they had developed bilateral laryngeal paralysis. Two of the horses died during severe bouts of dyspnoea six and eight months later and the third was killed shortly thereafter. Examination of the left and right recurrent laryngeal nerves from these horses showed a severe loss of myelinated fibres distally, especially in the left nerve. A similar but less severe lesion was seen in other long peripheral nerves, including the phrenic and digital nerves of the third horse. The spinal cord in two horses showed evidence of mild axonal degeneration which was not related to a particular tract or location. The fourth horse had bilateral laryngeal paralysis two years later. The acute clinical signs and delayed neurological sequelae seen in these horses were strongly suggestive of accidental organophosphate toxicity.     

Holding Power of Orthopedic Screws in Equine Third Metacarpal and Metatarsal Bones: Part II. Adult Horse Bone

Comparison was made of the holding power of 5.5 and 4.5 mm cortical orthopedic screws inserted into third metacarpal and metatarsal cadaver bones from 3- and 8-year-old horses. The tensile strength of these screws was tested mechanically. In nine comparative trials of these screws, 5.5 mm screws pulled out of bone in five trials at an average of 116.0 kg tensile force and broke in four trials at an average of 1383.2 kg. A 4.5 mm screw pulled out of bone at 834.5 kg in one trial, and screws broke at an average of 849.2 kg in eight trials. The larger 5.5 mm screw required a significantly greater (p = 0.022) pullout force than the mean force at 4.5 mm screw breakage. Fixation failure was due to screw breakage or bone shear, with 5.5 mm screws occasionally creating bone fragmentation during pullout. The average tensile breaking strengths of the 5.5 mm screws (1391.4 kg) and 4.5 mm screws (832.7 kg) determined mechanically were similar to forces at screw breakage during pullout testing in bone. Since the 5.5 mm screws have greater holding power and tensile strength than 4.5 mm screws, the use of the 5.5 mm screw in fracture repair in adult horses is recommended.     

世界银行倡导以农业促发展

当今世界的农业发展概况 当今世界的农业,广袤、多样且快速变化.如果地方层面、国家层面乃至全球层面都有健全的政策和支持性投入,今天的农业将为数以亿计的农村穷人摆脱贫困提供新的契机.农业向他们敞开脱贫道路包括家庭种植业和养殖业、高附加值的"新型农业"就业机会、新兴的农村非农产业创业和就业机会等等.     

Treatment of diplomonad intestinal parasites with magnesium sulphate at a commercial rainbow trout (Oncorhynchus mykiss) facility

Rainbow trout (average weight of 2 g) in fresh water experienced high mortality and were infected with a diplomonad intestinal parasite. Tanks of fish experienced an immediate reduction in mortality after an in-feed treatment with 3% Epsom salts for 2 d. Treatments had to be applied several times, but in each case there was a similar reduction in mortality.