Behavioral maintenance of high concentrations of blood ethanol and physical dependence in the rat

Rats maintained on an intermittent food schedule with an available ethanol solution drink to excess (13.1 grams of ethanol per kilogram of body weight, daily). Removal of ethanol produces symptoms of physical dependence including death from tonic-clonic seizures. Overindulgence in oral self-administration of an aqueous ethanol solution, resulting in unequivocal physical dependence, approximates a model of human alcoholism.     

Thermal properties of water: discontinuities questioned

Reports of discontinuities have been tabulated, and those dealing with vibrational spectrum and volume have been examined in detail. No evidence has been found of any discontinuity greater than experimental error.     

Teratogenic evaluation of 2,4,5-T

The herbicide 2,4,5-trichlorophenoxyacetic acid is teratogenic and fetocidal in two strains of mice when administered either subcutaneously or orally and in one strain of rats when administered orally. The incidences of both cystic kidney and cleft palate were increased in the C57BL/6 mice as well as the incidence of cleft palate in the AKR mice. The incidence of cystic kidney was also increased in the rats. In addition, an increase in the ratio of liver weight to body weight in the mouse fetus and the occurrence of hemorrhagic gastrointestinal tract in the rat fetus suggest that this compound also has fetotoxic properties.     

Social comparison affects reward-related brain activity in the human ventral striatum

Whether social comparison affects individual well-being is of central importance for understanding behavior in any social environment. Traditional economic theories focus on the role of absolute rewards, whereas behavioral evidence suggests that social comparisons influence well-being and decisions. We investigated the impact of social comparisons on reward-related brain activity using functional magnetic resonance imaging (fMRI). While being scanned in two adjacent MRI scanners, pairs of subjects had to simultaneously perform a simple estimation task that entailed monetary rewards for correct answers. We show that a variation in the comparison subject's payment affects blood oxygenation level-dependent responses in the ventral striatum. Our results provide neurophysiological evidence for the importance of social comparison on reward processing in the human brain.     

Denitrification in the saturated zone of hydromorphic soils—laboratory measurement, regulating factors and stochastic modeling

Denitrification capacity (D_cap) was measured in 595 samples from the saturated zone of 18 hydromorphic soils by anaerobic incubation of K¹⁵NO₃ amended slurries in the laboratory and analyzing ¹⁵N₂+¹⁵N₂O in the sample headspace. Furthermore, texture, pH, C (total, dissolved, hot-water soluble organic and inorganic C), total N and sulfide were measured in order to model D_cap by multiple regression analysis. D_cap was significantly correlated with most properties, but exhibited closest relationships to electron donors (C_org, sulfide). Mean D_cap of the soil material groups sand, loam and peat was 0.13, 1.34 and 26.6 mg N kg⁻¹ d⁻¹. Regression models for predicting D_cap were varied in the selection of independent variables and in the differentiation of the source data-set. The models were found to be suitable to estimate mean D_cap of sites with medium or high activity. Best fits were obtained with the most complex models, but prediction for individual samples and for means of sites with low activity was not satisfactory with any of the models. The model based on organic C and total N and differentiating by type of soil material and position above or below the groundwater level was validated using an independent data-set of 46 samples from 10 sites of fluvial, glaciofluvial or glacial till sediments. The fluvial sediments exhibited satisfactory agreement between measured and predicted D_cap, whereas the other sites were overestimated because D_cap was too low and possibly because glacial till was not part of the source data-set. Our study provides for the first time statistical models of denitrification in shallow groundwater which are transferable to other sites with certain restrictions and which can thus be used for environmental modeling and soil mapping.     

Bali Barat: An Indonesian marine protected area and its resources

Since the early 1970s the Indonesian Government has tried to establish marine nature reserves. The initial marine protected areas, however, have not been successful, due to lack of enforcement, and the present account is of a site on the western tip of Bali, where it is hoped that the idea will come to fruition. The marine resources of this Reserve, Bali Barat, are described, together with the various ways in which they are at present being exploited. The plan developed for the Reserve aims to prohibit destructive uses, while allowing those which are not as yet considered damaging to the area. The needs for strict protection of certain sites for tourism and for subsistence uses have been reconciled through a system of zones. The experience gained from Bali Barat should enable effective marine reserve conservation to be extended to other parts of the country, and the Reserve could also contribute directly to education of the public, and to research and management expertise.     

The real-time stellar evolution of Sakurai's object

After a hot white dwarf ceases its nuclear burning, its helium may briefly and explosively reignite. This causes the star to evolve back into a cool giant, whereupon it experiences renewed mass ejection before reheating. A reignition event of this kind was observed in 1996 in V4334 Sgr (Sakurai's object). Its temperature decrease was 100 times the predicted rate. To understand its unexpectedly fast evolution, we have developed a model in which convective mixing is strongly suppressed under the influence of flash burning. The model predicts equally rapid reheating of the star. Radio emission from freshly ionized matter now shows that this reheating has begun. Such events may be an important source of carbon and carbonaceous dust in the Galaxy.     

Longevity and growth of <Emphasis Type="Italic">Acacia tortilis</Emphasis>; insights from <Superscript>14</Superscript>C content and anatomy of wood

Background  

Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb ¹⁴C content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt.