Operant control of neural events in humans

Human subjects were trained by traditional methods of instrumental conditioning to change the amplitude of a late component of the auditory evoked potential with and without oscilloscopic feedback of their performance.     

Protective effects of dietary l‐carnitine on tilapia hybrids (Oreochromis niloticus × Oreochromis aureus) reared under intensive pond‐culture conditions

Tilapia hybrids of Oreochromis niloticus × O. aureus with a starting weight of 90 g were grown for 57 days in 18 floating net‐cages set up in a fishpond (1.8 ha × 3 m deep; water temperature around 27 °C) at the Aquaculture Research Station in Dor, Israel. They were fed pellets of a commercial diet which contained 8.1 ppm natural l ‐carnitine. This diet was then supplemented with 150 or 450 ppm of l ‐carnitine. The results show that at the end of the 8‐week feeding trail, l ‐carnitine supplementation did not influence weight gain. The subsequent histological characteristics of the pond fish were compared with those of a separated group of their siblings kept in an indoor tank in clean flow‐through water. Normal and contact epi‐microscopy, contact fluorescent microscopy and contact microfluorometry with various fluorescent probes revealed that the fish fed the diet with 150 ppm of supplementary l ‐carnitine showed the lowest permeability to fluorescein in gills, gut and skin epithelia, the highest activity in the system of active transport for organic anions, and the highest levels of the multixenobiotic resistance transporter (MXRtr) for lipophilic/amphiphilic xenobiotics. The MXRtr activity in the liver bile canaliculi and renal proximal tubules of this group of fish was much higher than that of the other groups except those from the indoor tank. The intralysosomal accumulation of neutral red in their head kidney macrophages was also significantly higher. The results suggest that a low level of l ‐carnitine enrichment provides several protective effects in fish reared under intensive pond‐culture conditions.     

The effect of temperature on sensory quality,chemical composition and growth of carrots (Daucus carota L.). IL Constant diurnal temperatures under different seasonal light regimes

Summary

Carrots of cv. Panther F1 were grown in climate chambers at 9, 12, 15, 18 and 21°C, constant diurnal temperatures at three different periods of the year. The effect of varying solar radiation and temperatures were evaluated on growth, sensory attributes and chemical composition. Higher levels of light significantly increased most chemical and physical variables of the carrot roots. Temperature was the most important factor determining the variation in sensory and chemical variables, whereas for morphological features like root weight, root length and diameter measurements, light was more important than temperature. Principal component analysis (PCA) of chemical and physical variables explained 85% of the total variation by the first three principal components, the first component (PCI) being defined by physical variables, explained 46% of the variation, while the temperature related PC2 explained 32% of the variation. Prediction of sensory variables by chemical or physical variables by means of partial least square (PLS) was higher at low light intensity than at high light intensity.     

Smoking rain clouds over the Amazon

Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear "smoking" as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation.     

Computer vision

The field of computer vision is devoted to discovering algorithms, data representations, and computer architectures that embody the principles underlying visual capabilities. This article describes how the field of computer (and robot) vision has evolved, particularly over the past 20 years, and introduces its central methodological paradigms.     

Cigarette craving, smoking withdrawal, and clonidine

Clonidine, an alpha-2-adrenergic agonist, significantly reduces opiate withdrawal. Fifteen heavy smokers abstained from cigarettes on three separate occasions and received instead clonidine, placebo, or the benzodiazepine alprazolam. Clonidine and alprazolam diminished withdrawal symptoms. The two drugs suppressed anxiety, tension, irritability, and restlessness equally but clonidine had a greater effect than alprazolam on cigarette craving. These observations suggest that noradrenergic activity is a common feature in the pathophysiology of withdrawal and that a special relationship exists between central noradrenergic activity and craving.