Quantitative assessment of vegetation structural attributes from aerial photography

Cover of vegetation understorey and overstorey was determined from aerial photography at 1:25 000 and 1:40 000 scales by a grid sampling technique. Models were developed relating values of aerial cover to field cover as determined by intensive field measurement. The influence of photo-scale, photo colour, the angle of the image, shadow, the hiatus between aerial and field sampling, crown width, crown height, proportion of dead trees, drought prior to aerial sampling, land type, previously cleared vegetation and incline on explanatory models was also examined. The only variables that could be clearly interpreted as influencing the models were vegetation height, photo-scale and land type. Only the latter two variables are useful for predictive models. The smaller the scale of photography the greater the exaggeration of the aerial image of tree crowns. This probable result of photo graininess would be most significant when tree crowns are small, an inverse surrogate of tree height. Two-phase models were developed for predicting basal area and biomass from aerial cover. In most instances models were successful for predicting overstorey and understorey cover and for predicting total basal area and biomass. The technique offers a powerful and cost-effective method of assessing vegetation change over long time periods in a way that no other technique can duplicate.     

Antibacterial activity of antibiotic coated silicone grafts

PURPOSE: Postoperative infection remains one of the most serious complications of implantation of penile prostheses. Attempts to reduce the rate of infection by spraying the prosthesis with an antibiotic solution prior to implantation, along with perioperative antibiotics, have failed to eradicate infection. No published studies have evaluated the effect of antibiotic coating of penile prostheses. In this study, we evaluate the antibacterial effect of antibiotic-coated silicone strips as a surrogate for the penile prosthesis. MATERIALS AND METHODS: Strips coated with several different antibiotics were dipped in bacterial solutions containing Staphylococcus epidermidis or S. aureus and implanted subcutaneously in adult Sprague-Dawley rats. After a week, the strips were removed, and the number of bacteria on the strips and in the surrounding tissue were determined. The in vitro antibiotic activity of the antibiotic-coated strips against the same organisms was also determined. RESULTS: In the group of rats that received silicone strips contaminated in vitro with S. epidermidis, six of nine control rats yielded strips and tissues containing heavy bacterial growth. None of six strips coated with rifampin/minocycline yielded bacterial growth, nor did any of the seven strips coated with vancomycin. One of seven rats that received amikacin-coated strips had infection of the strip. The tissue results were similar to the strip results. In the group using S. aureus as the contaminating bacterium, the strips and tissues from eight of nine control rats yielded bacteria. None of the six rifampin/minocycline-coated strips yielded bacteria, while two of seven vancomycin-treated strips and two of six amikacin-coated strips were infected with S. aureus. The difference in bacterial growth between controls and antibiotic-coated strips reached a level of statistical significance for the rifampin/minocycline and vancomycin groups and was highly significant for the rifampin/minocycline groups. CONCLUSION: The experimental results presented here suggest that coating silicone graft material with antibiotics, particularly rifampin/minocycline, can reduce the incidence of graft colonization in contaminated wounds in rats, even in the absence of systemic antibiotics. These graft materials may prove useful in preventing the infection of penile prostheses.     

Phialophora verrucosa infection in a BMT patient

Phialophora is a dematiaceous fungus isolated from soil and wood. Human infections including chromoblastomycosis, mycotic keratitis, cutaneous infections, and prosthetic valve endocarditis have been reported. We report a case of fatal hemorrhage due to Phialophora verrucosa in a patient with prolonged neutropenia undergoing autologous bone marrow transplant (BMT) for acute myelogenous leukemia (AML). Bacterial infections complicated induction and consolidation chemotherapies. Liposomal amphotericin B (LAMB) was given from day +33 to day +72 for febrile neutropenia. Death occurred on day +74 due to tracheal hemorrhage. Autopsy revealed granulation tissue on the posterior wall of the trachea with fungal hyphae on histopathology; the tissue grew Phialophora verrucosa. In vitro susceptibility studies revealed a minimum inhibitory concentration to AmB of 0.1 microg/ml. This represents the first reported case of invasive P. verrucosa in a BMT patient leading to fatal hemorrhage, despite large cumulative doses of LAMB to which the organism remained susceptible.     

Neurological aspects of sinoatrial heart block

The symptoms of 100 patients with chronic cardiac sinoatrial disorder were analysed. The most common presenting features were syncope in 34 cases and dizziness in 22 cases. Over three-quarters of the patients had cerebral ischaemic symptoms at some stage of the disease. Diagnostic difficulties are often encountered and are illustrated by two case histories. Although sinoatrial disorder has been described in association with neuromuscular diseases, only one such example was found in this series. The patient had a limb girdle dystrophy with cardiomyopathy and diffuse disease of the cardiac conducting system. Muscle biopsy samples taken from 11 patients with idiopathic sinoatrial disorder were normal showing no evidence of subclinical muscular disease.     

NUMERICAL SIMULATIONS OF HIGHLY NONLINEAR STEADY AND UNSTEADY FREE SURFACE FLOWS

A numerical simulation model based on an open source Computational Fluid Dynamics (CFD) package-Open Field Operation and Manipulation (OpenFOAM) has been developed to study highly nonlinear steady and unsteady free surface flows. A two-fluid formulation is used in this model and the free surface is captured using the classical Volume Of Fluid (VOF) method. The incompressible Euler/Navier-Stokes equations are solved using a finite volume method on unstructured polyhedral cells. Both steady and unsteady free surface flows are simulated, which include: (1) a submerged NACA0012 2-D hydrofoil moving at a constant speed, (2) the Wigley hull moving at a constant speed, (3) numerical wave tank, (4) green water overtopping a fixed 2-D deck, (5) green water impact on a fixed 3-D body without or with a vertical wall on the deck. The numerical results obtained have been compared with the experimental measurements and other CFD results, and the agreements are satisfactory. The present numerical model can thus be used to simulate highly nonlinear steady and unsteady free surface flows.