Search Results - (Author, Cooperation:S. Ball)

2018-04-10

The American Association of Immunologists (AAI)

0022-1767

1550-6606

Medicine

2018-10-23

Nature Publishing Group (NPG)

2045-2322

Natural Sciences in General

2018-12-04

The American Association for Cancer Research (AACR)

1078-0432

1557-3265

Medicine

2012-02-22

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Biological Evolution ; Cyanobacteria/genetics ; Cyanophora/*genetics ; *Evolution, Molecular ; Gene Transfer, Horizontal ; Genes, Bacterial ; *Genome, Plant ; Molecular Sequence Data ; Photosynthesis/*genetics ; Phylogeny ; Symbiosis

0370-2693

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Physics

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Ferromagnetic resonance (FMR) and high field effective (HFE) linewidth measurements have been made at 10–90 GHz for low conductivity Mn substituted single crystal barium ferrite, BaFe12−xMnxO19, with x=0.1. The manganese compensates excess Fe2+ and reduces conductivity. Measurements were made on c-plane thin disks magnetized to saturation along the disk axis. A shorted waveguide technique was used to measure the FMR profiles and linewidths in the 55–90 GHz frequency range. High Q cavity techniques and an analysis procedure for the FMR high field tail response were used for the HFE linewidth determinations in the 10–60 GHz frequency range. The FMR linewidths increase linearly with frequency at 0.3 Oe/GHz and have a zero frequency intercept of 20 Oe. The HFE linewidths increase linearly with frequency at 0.4 Oe/GHz and have a zero frequency extrapolation of 4 Oe. This lower zero frequency extrapolation for the HFE linewidth supports an inhomogeneity origin for the 20 Oe FMR linewidth extrapolation. These data indicate intrinsic linewidths for barium ferrite of 0.3–0.4 Oe/GHz, a factor of 6–8 larger than intrinsic linewidths in single crystal yttrium iron garnet.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The frequency dependence of the ferromagnetic resonance (FMR) linewidth and effective linewidth has been measured in Mn doped single crystal barium hexaferrite (BaFe12−xMnxO19) with x=0.1. Mn doped samples were used to minimize conductivity losses. Measurements were made on c-plane thin disks magnetized to saturation along the disk axis and c direction. A shorted waveguide technique was used to measure the FMR profiles in the range of 55–90 GHz. The FMR field position increased linearly at 0.35 kOe/GHz, with a zero field extrapolation of 34.7 GHz as expected for uniform mode FMR in barium ferrite. The linewidth ΔH increased linearly with frequency at 0.29 Oe/GHz with a zero frequency extrapolation of 18 Oe. A high-Q cavity method was used to measure the high field effective linewidth, ΔHeffFF at 10, 20, 35, and 60 GHz. The effective linewidth increased linearly with frequency at 0.4 Oe/GHz, with a zero frequency extrapolation of 4 Oe. There were no dependencies of ΔH or ΔHeffFF on sample thickness. These results indicate that (1) eddy current contributions to ΔH and ΔHeffFF in these Mn doped barium ferrite materials are absent, (2) ΔHeffFF is significantly lower than ΔH and appears to be a good measure of the intrinsic losses, and (3) both linewidths increase linearly with frequency at about the same rate.These intrinsic linewidths in barium ferrite are still significantly greater than linewidths in yttrium iron garnet. Research sponsored in part by the United States Office of Naval Research, Contract No. N00014-90-J-4078. The single crystal samples were kindly provided by M. A. Wittenauer, Purdue University.

Electronic Resource

1467-8535

Blackwell Publishing Journal Backfiles 1879-2005

Education

Electronic Resource

1365-2427

Blackwell Publishing Journal Backfiles 1879-2005

Biology

1. We used a laboratory experiment to determine effects of a predator (other than straightforward prey consumption) and food availability, during the larval stage, on adult size, age at emergence and fecundity of Chironomus tentans.2. Predator presence and decreased food availability resulted in reduced adult emergence.3. Predator presence and food availability resulted in smaller size and greater age at emergence of male and female chironomids. There were no significant interactions between effects of predator presence and food availability.4. Predator presence had no significant effect on fecundity.5. Smaller size and greater age at emergence can have important implications for adult survival, size and age at first reproduction and, thus, intrinsic rate of population growth.

Electronic Resource

1365-3059

Blackwell Publishing Journal Backfiles 1879-2005

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

Different developmental stages of the inflorescence of pearl millet (Pennisetum americanum) were inoculated with zoospores of the downy mildew fungus (Sclerospora graminicola). Individual florets within a panicle were infected, with resultant malformation of any floral organs that were not fully differentiated at the time of infection. ‘Green-ear’ symptoms resulting from hyperplasia and hypertrophy of the host tissues were accompanied by both sexual and asexual sporulation of the fungus on the malformed plant parts. No grain set occurred in affected florets, indicating that secondary inoculum was able to cause yield reductions even at late stages in the host development. Infection of differentiated stigmas led to rapid dissolution and necrosis of tissue and prevented colonization by the pathogen. This failure suggests that seeds are unlikely to be infected internally.

Electronic Resource

1365-3059

Blackwell Publishing Journal Backfiles 1879-2005

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

Cyphomandra betacea (tree tomato) plants with stem lesions were observed in an orchard in Tungurahua province, Ecuador. Dissection of the stems showed the presence of black sclerotia. Further laboratory analysis and pathogenicity tests revealed that Sclerotinia sclerotiorum was the causal agent of the disease. Although recorded in New Zealand, this is the first report of the pathogen affecting tree tomato in Ecuador.

Electronic Resource

1365-3059

Blackwell Publishing Journal Backfiles 1879-2005

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

Oospore collections of Sclerospora graminicola, obtained from diverse locations in West Africa and India, were used to infect susceptible pearl millet plants. Asexual spores, collected from five infected plants from each collection were used as individual isolates to inoculate pearl millet seedlings, alone and in every possible combination to test for sexual compatibility type. Oospores were produced with some combinations of isolates but not others, indicating the presence of two compatibility types, designated g1 and G2 These were found in approximately equal proportions. There were also some isolates which produced a few oospores when inoculated alone. Tests for cross-compatibility were made by combining isolates of opposite sexual compatibility types from different collections. Not only were collections from within continents cross compatible but there was also cross-compatibility between isolates from different continents. The implications of such extensive outbreeding capacity in S. graminicola are considered.

Electronic Resource

1365-2761

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Medicine

Electronic Resource

1365-2486

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Energy, Environment Protection, Nuclear Power Engineering

Geography

The effects of elevated atmospheric CO2 (ambient + 340 μmol mol–1) on above-ground litter decomposition were investigated over a 6-week period using a field-based mesocosm system. Soil respiratory activity in mesocosms incubated in ambient and elevated atmospheric CO2 concentrations were not significantly different (t-test, P 〉 0.05) indicating that there were no direct effects of elevated atmospheric CO2 on litter decomposition.A study of the indirect effects of CO2 on soil respiration showed that soil mesocosms to which naturally senescent plant litter had been added (0.5% w/w) from the C3 sedge Scirpus olneyi grown in elevated atmospheric CO2 was reduced by an average of 17% throughout the study when compared to soil mesocosms to which litter from Scirpus olneyi grown in ambient conditions had been added. In contrast, similar experiments using senescent material from the C4 grass Spartina patens showed no difference in soil respiration rates between mesocosms to which litter from plants grown in elevated or ambient CO2 conditions had been added.Analysis of the C:N ratio and lignin content of the senescent material showed that, while the C:N ratio and lignin content of the Spartina patens litter did not vary with atmospheric CO2 conditions, the C:N ratio (but not the lignin content) of the litter from Scirpus olneyi was significantly greater (t-test;P 〈 0.05) when derived from plants grown under elevated CO2 (105:1 compared to 86:1 for litter derived from Scirpus olneyi grown under ambient conditions). The results suggest that the increased C:N ratio of the litter from the C3 plant Scirpus olneyi grown under elevated CO2 led to the lower rates of biodegradation observed as reduced soil respiration in the mesocosms. Further long-term experiments are now required to determine the effects of elevated CO2 on C partitioning in terrestrial ecosystems.

Electronic Resource

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

In a double-blind placebo-controlled study in nine healthy volunteers, the effects of single doses of oral enprostil (8.75, 17.5, 35 and 70 μg), taken before a standard breakfast, were assessed on the post-prandial release of gastrin into the plasma. All doses of enprostil caused a significant dose-related decrease in median post-prandial plasma gastrin concentration (range from — 29 to — 44%). In the same subjects, two doses of 25 mg indomethacin caused a significant (38%) increase in median post-prandial plasma gastrin concentration.

Electronic Resource

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Twenty-four-hour intragastric acidity and plasma gastrin concentration were measured in healthy subjects (n= 16), and patients with duodenal (n= 12) or gastric (n= 10) ulceration, or pernicious anaemia (n= 8). Median integrated 24-hour intragastric acidity was highest in duodenal ulcer patients and lowest in pernicious anaemia patients (1148 and 0 mmol. hour litre−1, respectively). Median integrated 24-hour plasma gastrin was highest in pernicious anaemia and lowest in the healthy subjects (9886 and 238 pmol. hour litre−1, respectively). Pernicious anaemia patients have unremitting hypergastrinaemia throughout the 24 hours. The results of this study not only provide a reference range of acidity and plasma gastrin in health and disease, but also will act as a baseline for future studies using antisecretory drugs.

Electronic Resource

1365-2036

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Simultaneous 24-hour intragastric acidity and plasma gastrin concentrations were measured in 12 duodenal ulcer patients before and on the twenty-eighth day of treatment with either ranitidine 150 mg b.d. or omeprazole 20 mg o.m. Median integrated 24-hour intragastric acidity was decreased significantly from 1148 to 490 and 36 mmol. hour litre−1 during treatment with ranitidine and omeprazole, respectively, whilst median intragastric 24-hour plasma gastrin was raised significantly from 328 to 799 and 1519 pmol. hour litre−1 respectively. When the results of all 48 experiments were considered together, there was a significant inverse correlation between the 24-hour integrated values for intragastric acidity and plasma gastrin concentration. Both drugs caused a significant elevation of plasma gastrin throughout the 24 hours, although ranitidine had no effect on intragastric acidity from 1900 to 2200 hours. When compared with similar profiles of acidity and gastrin in pernicious-anaemia patients, the modest elevations of plasma gastrin observed in this study suggest that neither drug will be associated with clinically relevant enterochromaffin-like cell proliferation in duodenal ulcer patients.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Brown dwarfs are not massive enough to sustain thermonuclear fusion of hydrogen at their centres, but are distinguished from gas-giant planets by their ability to burn deuterium. Brown dwarfs older than ∼10 Myr are expected to possess short-lived magnetic fields and to emit radio and ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] To evaluate the activity of the compounds, they were mixed in chick starter mash of known composition and fed to one-week-old cockerels, starting one day before they were inoculated orally with approximately 200,000 sporulated oocysts of Eimeria tenella or E. necatrix, or 50,000 sporulated oocysts ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The maximum number of oocysts passed in the faeces for each oocyst fed to a bird (reproductive potential) suggests that a third schizont stage must be present. Brackett and Bliznick9 obtained a maximum experimental reproductive potential for E. acervulina of 72,000 and we have obtained a value of ...

Electronic Resource