Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.     

Florfenicol in Atlantic salmon, Salmo salar L.: field evaluation of efficacy against furunculosis in Norway

Abstract. The efficacy of florfenicol in the control of natural outbreaks of furunculosis in Atlantic sallmon, Salmo salar L. was evaluated on five Norwegian farms during the summer of 1992. A total of 115 245 first- or second-generation fish received florfenicol with feed at a dose rate of 10mgkg ¹body weight daily for 10 consecutive days. Comparisons were made with similar pens of fish medicated with the preferred treatment for eaeh location. In the 10 days following introduction of therapy, all treatments were associated with a rapid decline in mortality caused by infection with Aeromonas salmonicida. Florfenicol-medicated salmon had a lower specific mortality than those given oxolinie acid, flumequine or a trimethoprim and sulphadiazine eombination. No adverse reactions to treatment with florfenicol were observed.     

Modulation of diversity by grazing and mowing in native tallgrass prairie

Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity.     

Functional and morphological studies on blood platelets in a thrombasthenic horse

A four-year-old Standardbred gelding presented with a 3.5 year history of intermittent epistaxis and spontaneous submucosal petechiae and ecchymoses in the nares and the mouth. Routine haematological and biochemical examinations were unremarkable. A thrombocytopathy was suspected when activated partial thromboplastin time, one stage prothrombin time, plasma fibrinogen and the platelet count were all normal. The patient's platelets failed to aggregate with serotonin, adenosine diphosphate, collagen (at 20 micrograms/ml) or the endoperoxide analogue U46619. Very high levels of collagen (100 micrograms/ml) did cause aggregation. The response to the calcium ionophore A23187 was reduced and although complete degranulation occurred the resulting aggregates were unstable. Thromboxane generation in response to collagen and ADP was inferred from the concentration of its stable metabolite thromboxane B2 and was reduced. A diagnosis of a thrombasthenia-like syndrome possibly equivalent to Type II Glanzmann's thrombasthenia in people was made.