Search Results - (Author, Cooperation:D. Fowler)

2018-01-24

Wiley-Blackwell

2045-7758

Biology

2011-02-01

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Female ; Habenula/drug effects/*metabolism/physiology ; Male ; Mice ; Mice, Knockout ; Nicotine/*metabolism/pharmacokinetics/pharmacology ; Rats ; Receptors, Nicotinic/deficiency/genetics/*metabolism ; Reward ; *Signal Transduction/drug effects ; Tobacco Use Disorder/genetics/metabolism

2018-03-22

Nature Publishing Group (NPG)

2041-1723

Biology

Chemistry and Pharmacology

Natural Sciences in General

Physics

2018-02-09

American Heart Association (AHA)

0009-7330

1524-4571

Medicine

Basic Science Research, Calcium Cycling/Excitation-Contraction Coupling, Myocardial Biology, Physiology

2012-01-17

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Aerosols ; *Air Pollutants/analysis ; Air Pollution/*prevention & control ; *Climate Change ; Computer Simulation ; Cost-Benefit Analysis ; *Food Supply ; *Health ; Humans ; *Methane/analysis ; Mortality, Premature ; *Ozone/analysis ; *Soot/analysis

2018-01-12

American Heart Association (AHA)

1942-325X

1942-3268

Medicine

Arrhythmias, Sudden Cardiac Death, Genetic, Association Studies, Genetics

1089-7550

AIP Digital Archive

Physics

Magnetism in ultrathin (1–10 ML) Fe films grown on Cu(100) has been studied by spin-polarized secondary electron emission spectroscopy. The variation of the magnetization with temperature and oxygen adsorption was investigated for various film thicknesses. The orientation of the magnetization for films between 5 and 6 ML thick switches reversibly between perpendicular (at low temperature) to in-plane (at high temperature). The switching transition temperature decreases with increasing film thickness, and is accompanied by a loss of long-range order over a range of 20–30 K. The transition is attributed to the temperature dependence of the perpendicular anisotropy. The effect of oxygen adsorption onto films with perpendicular remanence is to first suddenly turn the magnetization into the plane at a critical coverage, and then to kill the magnetization gradually with continued exposure. This indicates that the uniaxial surface anisotropy at the Fe-vacuum interface plays a major role in the magnetization of the film.

Electronic Resource

1475-2743

Blackwell Publishing Journal Backfiles 1879-2005

Geosciences

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract. Inputs of acidity to the ground arise through two distinct routes: wet deposition which includes all acidity deposited in rain and snow and dry deposition, the direct sorption of SO2, NO2 or HNO3 gases by vegetation or soil surfaces. The acidity from dry deposition of SO2 and NO2 is created during the oxidation of deposited SO2 and NO2 to SO24 and NO3− respectively. The areas of Britain experiencing the largest wet deposition of acidity are the high rainfall areas of the west and north, in particular the west central highlands of Scotland, Galloway and Cumbria where inputs exceed 1 kp H+ ha−1 annually. Wet deposited acidity in the east coast regions of Britain is in the range 0.3–0.6 kg H+ ha−1 a−1. Monitoring data for rainfall acidity at rural sites throughout northern Britain show a decline in deposited acidity of about 50% during the last six years. Dry deposition is largest in the industrial midlands and southeast England and in the central lowlands of Scotland, where concentrations of SO2 are largest. In these regions the dry deposition of SO2 following oxidation may lead to acid inputs approaching 3 kg H+ ha−1 a−1 and greatly exceeding wet deposition.

Electronic Resource

1439-0523

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Synthetic hexaploid wheat, produced by combining tetraploid wheat (AB genome) with Triticum tauschii (D genome), was crossed to modern hexaploid wheat (Triticum aestivum ABD genome) in an attempt to introduce new cold hardiness genes into the common hexaploid wheat gene pool. The cold hardiness levels of F) hybrids ranged from similar to parental means to equal to the hardy parent, indicating that cold hardiness was controlled by both additive and dominant genes. As expected when dominant gene action is involved, differences between F2 and parental means were smaller than comparable differences in the F., Frequency distributions of F2—derived F3 lines also suggested that dominant genes were involved in the control of cold hardiness in some crosses. Heritability estimates for cold hardiness ranged from 63 to 70 % indicating that selection for cold hardiness should be effective in populations arising from crosses between common and synthetic hexaploid wheat. However, high selection pressure on the progeny of crosses that included the most hardy T. aestivum, T. durum, and T. tauschii accessions as parents did not identify transgressive segregates for improved cold hardiness. These observations indicate that the close wheat relatives, sharing common genomes with T. aestivum, are not promising sources of new genes to increase the maximum cold hardiness potential of common hexaploid wheat.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract. A temperate grassland model has been used to simulate carbon sequestration under various environmental conditions. The results suggest that the CO2 and nitrogen fertilization that has occurred may contribute appreciably to the so-called missing carbon sink, which it has been suggested must exist to balance the global carbon budget.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract Two-year-old seedlings of Picea rubens, growing in open-top chambers in Scotland were treated twice weekly from July 1987 to December 1987, with mist containing ammonium sulphate and nitric acid at a pH of either 2.5 or 5.0. The response of photosynthesis and stomatal conductance to light flux density and carbon dioxide concentration were measured in March 1989. Leaf chlorophyll a and b contents were also measured. Acid mist (pH 2.5) resulted in several significant changes. First, both the rate of light saturated photosynthesis (Amax) and CO2- saturated rate of photosynthesis (J) were substantially increased, when expressed per unit leaf area. Second, the apparent quantum yield and chlorophylls a and b content increased. Third, as a consequence of the greater chlorophyll content of the leaves treated with acid mist, the rate of Amax, and J, expressed per unit chlorophyll, was substantially reduced in pH 2.5 treated branches. Stomatal conductance was enhanced at all but the highest light flux densities, and was independent of the CO2 concentration, remaining high for all values of CO2 concentration used. These results show that acid mist caused a number of responses in the gas exchange and photosynthetic properties of red spruce.

Electronic Resource

1365-2486

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Energy, Environment Protection, Nuclear Power Engineering

Geography

The exchange of CH4 between tropical forests and the atmosphere was determined by simultaneously measuring the net CH4 flux at the soil surface and assessing the flux contribution from soil-feeding termite biomass, both within the soil profile and in mounds. In Cameroon the flux of CH4 ranged from a net emission of 40.7 ng m–2 s–1 to a net CH4 oxidation of –53.0 ng m–2 s–1. Soil-inhabiting termite biomass was significantly correlated with CH4 flux. Termite mounds emitted up to 2000 ng s–1 mound–1. Termite-derived CH4 emission reduced the soil sink strength by up to 28%. Disturbance also had a strong effect on the soil sink strength, with the average rate of CH4 oxidation, at – 17.5 ng m–2 s–1, being significantly smaller (≈ 36%) at the secondary forest site than the –27.2 ng m–2 s–1, observed at the primary forest site. CH4 budgets calculated for each site indicated that both forests were net sinks for CH4 at – 6.1 kg ha–1 y–1 in the near-primary forest and – 3.1 kg ha–1 y–1 in the secondary forest.In Borneo, three forest sites representing a disturbance gradient were examined. CH4 oxidation rates ranged from 0 to – 32.1 ng m–2s–1 and a significant correlation between the net flux and termite biomass was observed only in an undisturbed primary forest, although the biomass was insufficient to cause net emission of CH4. Rates of CH4 oxidation were not significantly different across the disturbance gradient but were, however, larger in the primary forest (averaging – 15.4 ng m–2 s–1) than in an old-growth secondary forest (–13.9 ng m–2s–1) and a young secondary re-growth (– 10.8 ng m–2s–1). CH4 flux from termite mounds ranged from net oxidation in an abandoned mound to a maximum emission of 468 ng s–1 mound–1. CH4 budgets calculated for each site indicated that CH4 flux from termite mounds had an insignificant effect on the budget of CH4 at the regional scale at all three forest sites. Annual oxidation rates were – 4.8, – 4.2 and – 3.4 kg ha–1 y–1 in the primary, secondary and young secondary forests, respectively.

Electronic Resource

1365-2486

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Energy, Environment Protection, Nuclear Power Engineering

Geography

This paper reports the range and statistical distribution of oxidation rates of atmospheric CH4 in soils found in Northern Europe in an international study, and compares them with published data for various other ecosystems. It reassesses the size, and the uncertainty in, the global terrestrial CH4 sink, and examines the effect of land-use change and other factors on the oxidation rate.Only soils with a very high water table were sources of CH4; all others were sinks. Oxidation rates varied from 1 to nearly 200 μg CH4 m−2 h−1; annual rates for sites measured for ≥1 y were 0.1–9.1 kg CH4 ha−1 y−1, with a log-normal distribution (log-mean ≈ 1.6 kg CH4 ha−1 y−1). Conversion of natural soils to agriculture reduced oxidation rates by two-thirds –- closely similar to results reported for other regions. N inputs also decreased oxidation rates. Full recovery of rates after these disturbances takes 〉 100 y. Soil bulk density, water content and gas diffusivity had major impacts on oxidation rates. Trends were similar to those derived from other published work. Increasing acidity reduced oxidation, partially but not wholly explained by poor diffusion through litter layers which did not themselves contribute to the oxidation. The effect of temperature was small, attributed to substrate limitation and low atmospheric concentration.Analysis of all available data for CH4 oxidation rates in situ showed similar log-normal distributions to those obtained for our results, with generally little difference between different natural ecosystems, or between short-and longer-term studies. The overall global terrestrial sink was estimated at 29 Tg CH4 y−1, close to the current IPCC assessment, but with a much wider uncertainty range (7 to 〉 100 Tg CH4 y−1). Little or no information is available for many major ecosystems; these should receive high priority in future research.

Electronic Resource

1440-1681

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

1. Transplacental transfer of the anti-epileptic agent phenytoin (PHT), its phase I metabolite, p-hydroxy-phenytoin (p-OH-PHT), and its phase II conjugate p-OH-PHT-glucuronide, was studied in term placental lobules perfused single pass in both maternal and fetal circuits.2. Ratios of clearance of PHT, p-OH-PHT and p-OH-PHT-glucuronide to clearance of antipyrine were 1.08 ± 0.03, 0.52 ± 0.02 and 0.12 ± 0.01 (mean and s.e.m.), respectively.3. Transfer was positively correlated with lipophilicity as measured by the apparent partition coefficient determined between octanol and pH 7.4 buffer.

Electronic Resource

1365-2621

Blackwell Publishing Journal Backfiles 1879-2005

Process Engineering, Biotechnology, Nutrition Technology

Seventy-two process variables, based on a matrix of aw nature of controlling solute, pH, and the addition of sodium citrate and sodium benzoate were examined with a view t o devising a food preservation system for ambient temperatures. Growth of a challenge‘cocktail’ of Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Streptococcus faecalis, Lactobacillus casei and Clostridiurn perfringens, was assessed in a Brain Heart Infusion broth based model system. Each of the controlling factors had an effect on growth. The addition of sodium citrate (2% w /v) and sodium benzoate (2000 mg/I) enhanced the inhibitory effect. Reduction in aw (1.00–0.94) and pH (7.0–5.5) in combination or as separate controlling factors increased any inhibition. Combinations of sodium chloride and glycerol were used as the controlling solute, and increasing the proportion of sodium chloride resulted in suppressed growth, irrespective of any change in aw or pH. Combinations of sodium citrate and sodium benzoate with a pH less than 6.0 and an a, less than 0.95 inhibited any growth during a 42 day incubation period at 37°C, irrespective of the controlling solutes studied.

Electronic Resource

0022-0671

Education

0022-0671

Education

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The term 'acid rain' refers to rain more acid than water in equilibrium with atmospheric concentrations of carbon dioxide (pH 5.6, 2.5 jxEquiv. H+1"1). Although several factors are involved, the areas in Scandinavia with significantly altered fish populations are subject to rainfall acidities of ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] In the first method the variation of concentration x of sulphur dioxide with height z is measured. Because of deposition at the surface and eddy diffusion in the atmosphere the concentration decreases toward the surface and the flux is given by F=K(z) (1) where K(z) is the eddy diffusivity for ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Understanding how complex systems respond to change is of fundamental importance in the natural sciences. There is particular interest in systems whose classical newtonian motion becomes chaotic as an applied perturbation grows. The transition to chaos usually occurs by the gradual destruction ...

Electronic Resource