Circulation and melting beneath the ross ice shelf

Thermohaline observations in the water column beneath the Ross Ice Shelf and along its terminal face show significant vertical stratification, active horizontal circulation, and net melting at the ice shelf base. Heat is supplied by seawater that moves southward beneath the ice shelf from a central warm core and from a western region of high salinity. The near-freezing Ice Shelf Water produced flows northward into the Ross Sea.     

METHOD FOR THE DETECTION OF INDOLE

A simple and sensitive method for the detection of indole in cultures, urine, sewage, etc., is presented. The indole is extracted with chloroform and is then treated with a modified Ehrlich reagent. The possibility of use for the detection of water pollution is indicated.     

Underplanting to sustain future stocking of oak (Quercus) in temperate deciduous forests

New Forests - Oaks (Quercus spp.) are one of the most important tree taxa in the northern hemisphere. Although they are dominant in mixed species forests and widely distributed, there are frequent...     

Efficacy and Toxicity of Tocainide for the Treatment of Ventricular Tachyarrhythmias in Doberman Pinschers With Occult Cardiomyopathy

Tocainide was administered to 23 cardiomyopathic Doberman Pinschers at doses of 15 to 25 mg/kg tid. These doses produced peak (2–hour) serum concentrations of 6.2 to 19.1 mg/L and trough (8–hour) serum concentrations of 2.3 to 11.1 mg/L. Anorexia and gastrointestinal disturbances occurred in 8 dogs (35%) at doses (15.6 to 25.0 mg/kg) that were not different from those (16.0 to 26.0 mg/kg) received by dogs that did not experience toxicity. Doses producing peak serum concentrations that were either greater or less than 14 mg/L were not different. Likewise, doses producing trough values that were either greater or less than 6 mg/L were not different. The mean dose that produced peak serum concentrations of 10 to 13.6 mg/L and trough concentrations of 4.2 to 10.0 mg/L was 17.9 mg/kg, and was associated with anorexia in 4 dogs. Mean peak serum concentrations associated with toxicity (14.4 mg/L) were significantly higher ( P = .02) than dogs not experiencing toxicity (11.8 mg/L). Serious adverse effects occurred in 7 of 12 dogs (58%) receiving tocainide for longer than 4 consecutive months. Progressive corneal endothelial dystrophy occurred in 3 dogs. Although a causal effect could not be proven, 6 dogs experienced renal dysfunction during treatment. Drug doses in these 7 dogs were similar to those received by other dogs. At least a 70% reduction of the total numbers of ventricular premature contractions occurred in 80% of dogs treated, and ventricular tachycardia was eliminated in 90% of affected dogs by the time of the first post-treatment Holter recording. Long-term control of ventricular tachyarrhythmias was difficult to achieve in some dogs when the left ventricular shortening fraction was less than approximately 17%. J Vet Intern Med 1996;10:235–240. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Freshening of the Ross Sea during the late 20th century

Ocean measurements in the Ross Sea over the past four decades, one of the longest records near Antarctica, reveal marked decreases in shelf water salinity and the surface salinity within the Ross Gyre. These changes have been accompanied by atmospheric warming on Ross Island, ocean warming at depths of approximately 300 meters north of the continental shelf, a more negative Southern Oscillation Index, and thinning of southeast Pacific ice shelves. The freshening appears to have resulted from a combination of factors, including increased precipitation, reduced sea ice production, and increased melting of the West Antarctic Ice Sheet.     

Naturally occurring auxin transport regulators

The process of polar auxin transport, central to a plant's auxin relations, can be inhibited by a group of synthetic compounds that apparently act by binding to a plasma membrane protein known as the naphthylphthalamic acid (NPA) receptor. No endogenous ligand to the NPA receptor, capable of affecting polar auxin transport in plants, has yet been found. It is now shown that a group of flavonoids-including quercetin, apigenin, and kaempferol-can specifically compete with [(3)H]NPA for binding to its receptor and can perturb auxin transport in a variety of plant tissues and transport systems in a manner closely paralleling the action of synthetic transport inhibitors. Because the active flavonoids are widely distributed in the plant kingdom and exert their effects at micromolar concentrations approximating likely endogenous levels, they may act as natural auxin transport regulators in plants.     

Phylogenetic MCMC algorithms are misleading on mixtures of trees

Markov chain Monte Carlo (MCMC) algorithms play a critical role in the Bayesian approach to phylogenetic inference. We present a theoretical analysis of the rate of convergence of many of the widely used Markov chains. For N characters generated from a uniform mixture of two trees, we prove that the Markov chains take an exponentially long (in N) number of iterations to converge to the posterior distribution. Nevertheless, the likelihood plots for sample runs of the Markov chains deceivingly suggest that the chains converge rapidly to a unique tree. Our results rely on novel mathematical understanding of the log-likelihood function on the space of phylogenetic trees. The practical implications of our work are that Bayesian MCMC methods can be misleading when the data are generated from a mixture of trees. Thus, in cases of data containing potentially conflicting phylogenetic signals, phylogenetic reconstruction should be performed separately on each signal.