Forest fires: An example of self-organized critical behavior

Despite the many complexities concerning their initiation and propagation, forest fires exhibit power-law frequency-area statistics over many orders of magnitude. A simple forest fire model, which is an example of self-organized criticality, exhibits similar behavior. One practical implication of this result is that the frequency-area distribution of small and medium fires can be used to quantify the risk of large fires, as is routinely done for earthquakes.     

Importance of Staphylococcus hyicus ssp hyicus as a cause of arthritis in pigs up to 12 weeks of age

Lame pigs, up to 12 weeks of age, were necropsied to establish a diagnosis. Of 175 pigs examined, 165 were confirmed to have arthritis by histopathological examination of joint tissues. Lesions were most common in the elbow and tarsal joints and least common in the joints of the feet. Typically, there was severe fibrinopurulent inflammation of synovial membranes regardless of the bacteria isolated. A bacterial aetiology was found in 114 (69%) of the 165 pigs. In arthritic pigs in which an aetiology was established the causative agents were Staphylococcus hyicus ssp hyicus (24.6%), Streptococcus equisimilis (26.3%), Actinomyces pyogenes (13.2%), Staphylococcus aureus (7.9%) and Haemophilus parasuis (7.9%). While gender did not affect the prevalence of arthritis, there was an age influence, most of the pigs culled for arthritis being under 6 weeks of age.     

Ecophysiological attributes of the native Acer saccharum and the exotic Acer platanoides in urban oak forests in Pennsylvania, USA

When the exotic Acer platanoides L. (Norway maple) and the native A. saccharum Marsh. (sugar maple) grow together in the understories of urban Quercus forests in the eastern USA, average annual height growth increments are nearly twice as large in A. platanoides as in A. saccharum, 19.26 +/- 3.22 versus 10.01 +/- 1.69 cm. We examined several ecophysiological mechanisms that might be associated with the superior invasive ability and growth of A. platanoides in two urban oak forests in Pennsylvania. Leaf longevity was 12 days greater in A. platanoides than in A. saccharum. In addition, leaf mass/leaf area ratio was greater in A. platanoides than in A. saccharum (2.67 +/- 0.03 versus 2.32 +/- 0.02 mg cm(-2)); however, leaf thickness was significantly lower in A. platanoides than in A. saccharum suggesting that A. platanoides contains more dense palisade and mesophyll cell layers than A. saccharum. Field net photosynthesis (mass basis) and photosynthetic light response curves (area basis) indicated significantly greater carbon assimilation, and nitrogen and phosphorus use efficiencies in A. platanoides than in A. saccharum. Acer platanoides also exhibited higher water use efficiency than A. saccharum (0.88 +/- 0.12 versus 0.32 +/- 0.09 mmol CO(2) mol(-1) H(2)O). Acer platanoides exhibited significantly lower osmotic potentials than A. saccharum, but a similar relative water content at zero turgor. We conclude that A. platanoides utilizes light, water and nutrients more efficiently than A. saccharum.     

Investigation of osteochondrosis in grazing beef cattle

Severe lameness attributed to osteochondrosis is described in an extensively managed Brahman herd grazing on improved native pasture. Clinical signs were observed in five animals, three of which were necropsied. The most prominent lesions were in the elbow and stifle joints. There was multiple fissuring and ulceration of thickened articular cartilage with numerous osteochondral bodies present in the joint spaces. All affected animals were entire males sharing a common ancestral sire. Inheritance and gender were suspected to be contributing factors in the development of the disease.     

A Competitive Dipstick Enzyme Immunoassay for Diagnosis of Early Pregnancy in Bovine

Early pregnancy diagnosis in bovines is one of the important aspects in efficient dairy farm management. In order to develop a competitive enzyme immunoassay (EIA) employing low cost reagents, anti‐progesterone antiserum and progesterone‐penicillinase enzyme conjugate were prepared. Using this anti‐serum and conjugate along with pencillinV–starch–iodine substrate system, the competitive EIA was standardized. In the experiment, danazol, a weak androgen used to extract the progesterone bound to proteins in milk, was included after standardizing the optimum concentration. Incubation period and temperature and pH of the reaction mixture were also optimized. The developed test was validated with milk samples obtained from dairy farm and individual animal owners. Confirmation of the pregnancy was made by per rectum examination of the genital tract around 60 days post‐insemination. The user friendly test procedure showed sensitivity and specificity of 83.3% and 87.5%, respectively as compared with residual binding method which was earlier developed in the laboratory with sensitivity and specificity of 100% and 87.5% respectively.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.     

Serratospiculosis in a New Zealand Falcon (Falco novaeseelandiae)

CASE HISTORY: An adult New Zealand falcon was presented with metacarpal fractures in the left wing.

CLINICAL FINDINGS: In addition to the fractures, radiographs revealed an area of opacity in the air sacs. A few days after hospitalisation and initiation of treatment of the fractures, the bird developed signs of respiratory disease; the area of opacity was found to have increased in size and density. Treatment with antibiotics and nebulisation was commenced; the bird initially responded but respiratory signs subsequently worsened and the bird died. At necropsy, air sacculitis and bronchopneumonia were associated with numerous nematodes in the air sacs, which were morphologically consistent with Serratospiculum guttatum.

DIAGNOSIS: Serratospiculosis

CLINICAL RELEVANCE: The discovery of this parasite and the associated disease for the first time in New Zealand indicates that it should be considered in the differential diagnosis of respiratory disease in falcons and possibly other raptors in New Zealand.