Search Results - (Author, Cooperation:C. Sheppard)

2014-09-23

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; *Global Warming ; *Islands

1089-7550

AIP Digital Archive

Physics

A confocal interference microscope incorporating an electro-optic phase modulator has been used to make simultaneous measurements of the inphase and quadrature components of the confocal signal as a reflecting surface is scanned axially, the so-called V(z) response. Comparison with previously published theoretical predictions is seen to be favorable.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1744-6570

Blackwell Publishing Journal Backfiles 1879-2005

Psychology

Electronic Resource

0022-0671

Education

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] SIR,The Great Chagos Bank, 615S, 72 E is all that remains of a once gigantic atoll. The dry land now consists of eight small islands set on the rim of the atoll and an outlying group of six other islands collectively called Egmont. Together they constitute a terrestrial habitat of only 828 ha, of ...

Electronic Resource

0031-9422

^1^3C NMR ; amentoflavones ; dihydro-derivatives. ; hinokiflavones ; methyl ethers

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Electronic Resource

1522-9602

Springer Online Journal Archives 1860-2000

Biology

Mathematics

Abstract A situation is considered in which a fluid containing a substance flows through a vessel at a constant rate, the substance being permeable to the vessel wall. In the region outside the vessel there is supposed to be rapid mixing in the direction perpendicular to the axis of the vessel but no mixing longitudinally. The solution for the spatial distribution at any time is given for the case of an arbitrary initial distribution along the vessel length in the absence of an input. The solution is also given for the case of a single impulsive input, the concentration being initially zero everywhere.

Electronic Resource

1522-9602

Springer Online Journal Archives 1860-2000

Biology

Mathematics

Abstract A modification is presented of an earlier theory of the mixing of dye following injection into the circulation. Approximate theoretical relations are given for the concentration of dye in the right heart and in the aorta following right atrial injection. It is shown that when the probability distribution of transit times around the circulation has a prolonged tail, mixing waves are now inscribed about a quasi-exponential relation. Later in time the relation levels off to a uniform asymptotic concentration corresponding to an equilibrium volume of dilution.

Electronic Resource

1572-817X

Springer Online Journal Archives 1860-2000

Electrical Engineering, Measurement and Control Technology

Physics

Abstract A scanning optical microscope in which an image is produced from the generation of optical second harmonics within the specimen has been constructed. Pictures have been obtained from various crystals which show high contrast levels and detail not visible with the conventional microscope.

Electronic Resource

1572-817X

Springer Online Journal Archives 1860-2000

Electrical Engineering, Measurement and Control Technology

Physics

Abstract A scanning optical microscope is used to measure directly the refractive-index profile of an optical fibre. The effects of illuminating the fibre end with a highly convergent beam of light are considered.

Electronic Resource

1570-7458

Lymantria dispar ; dietary nitrogen ; nutritional indices ; gypsy moth ; larval lipid ; artificial diet ; host plants

Springer Online Journal Archives 1860-2000

Biology

Abstract Nutritional indices, development rates, percent dry weights and total lipids were determined in gypsy moth larvae (Lymantria dispar L.) reared on a high wheat germ (HWG) diet or diets prepared from lyophilized, ball-milled oak or pine foliage as the only source of dietary nitrogen (N). With regard to both total and proteinaceous N content, HWG diet〉oak diet〉pine diet. All nutritional indices measured were significantly lower in second instars fed pine diet vs. oak diet. Protein supplementation of pine diet with either casein or ovalbumin to bring total N up to the level present in oak diet resulted in small increased in approximate digestibility (AD) and effciency of conversion of ingested food (ECI), but relative growth rate (RGR) remained unaffected. The low RGR of larvae fed pine diet (unsupplemented or protein supplemented), as compared to those fed HWG or oak diet, was accompanied by significantly lower larval percent dry weight and percent total lipid. In contrast, RGR, larval percent dry weight and total lipid values were comparable in second instars fed HWG or oak diet. Insects reared from the first through the final instar on oak diet exhibited lower pupal weights compared to those reared on HWG. Casein addition to oak diet generally resulted in even more extended larval development times and further reduced pupal weights, but wheat germ addition to oak diet did not alter development rates and caused an increase in pupal weights.

Electronic Resource

0022-3980

Psychology

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] SIR-A recent letter1 by Rothenhausler and Knoll considered the microscopic imaging of low-contrast samples and presented images of molecular films formed by the technique of surface-plasmon microscopy. It was stated that monolayer films do not provide sufficient contrast to be visible with either ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] USING the three-inch phosphorus-bakelite plaques developed at Oak Ridge National Laboratory1, we have devised a technique for exposing cells to beta-particles which permits an accurate determination of the amount of beta-radiation to which the cells have been exposed. These plaques yield pure ...

Electronic Resource

1432-1076

Key words Hyperhomocysteinemia ; Polymorphism ; Mutations ; Cobalamin ; Vitamin B12

Springer Online Journal Archives 1860-2000

Medicine

Abstract Methylenetetrahydrofolate reductase and cobalamin-dependent methionine synthase catalyze the penultimate and ultimate steps in the biosynthesis of methionine in prokaryotes, and are required for the regeneration of the methyl group of methionine in mammals. Defects in either of these enzymes can lead to hyperhomocysteinemia. The sequences of the human methylenetetrahydrofolate reductase and methionine synthase are now known, and show clear homology with their bacterial analogues. Mutations in both enzymes that are known to occur in humans and to be associated with hyperhomocysteinemia affect residues that are conserved in the bacterial enzymes. Structure/function studies on the bacterial proteins, summarized in this review, are therefore relevant to the function of the human enzymes; in particular studies on the effects of bacterial mutations analogous to those causing hyperhomocysteinemia in human may shed light on the defects associated with these mutations.

Electronic Resource

1432-1793

Springer Online Journal Archives 1860-2000

Biology

Abstract Light profiles beneath the tabular coral species Acropora cytherea and A. hyacinthus were examined at Rib and Broadhurst Reefs, central Great Barrier Reef, in November 1980. They show a strongly decreasing illumination gradient towards the central stem. Beneath tables at 10m deep, which receive about 7.0 mW cm−2 at solar noon, substrate irradiance falls to a minimum of about 5% ambient or to about 0.4 mW cm−2. Thus, from previously reported compensation values, most sub-table substrate may receive above-compensation irradiance. Illumination beneath tables screened by foil is significantly lower. The coral communities beneath tables of these two species plus those of A. subulata and A. clathrata support an average 26 colonies m−2, at a cover of 40%, nearly identical to adjacent, unshaded quadrats. Species richness is likewise very similar. Species richness and colony density beneath the tables increase inwards from the perimeter of the shaded areas, decreasing only near the central stems. Dark adaptation and reduced competitive and grazing pressure are suggested explanations for the latter. It is concluded that shading does not provide a significant competitive advantage for Acropora spp. tables at 10 m deep.

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract 27Al and 29Si magic-angle spinning(MAS) nuclear magnetic resonance(NMR)and complementary X-ray diffraction (XRD) studies of carbothermal formation of sialons from kaolinite and halloysite confirm that the reaction involves the initial formation of mullite (3Al2O3·2SiO2) and amorphous silica. In the presence of carbon, Si-N bonds are formed at ≈1200 °C, giving a continuum of silicon oxynitride compositions which become progressively more N-rich. These do not become sufficiently ordered to be detected by XRD until later in the reaction, when crystalline silicon oxynitride, possibly containing a little Al (O′-sialon) and x-phase sialon are formed, followed by β′-sialon. The O′- and x-phase sialons are transitory, but the β′-sialon persists throughout the reaction. Si-O bonds survive the destruction of the mullite and persist throughout the reaction, especially with kaolinite starting material. The 29Si MAS NMR results indicate that Si-C bonds are formed later in the reaction than previously suggested, the SiC phase behaving more like a secondary product than a transitory intermediate. Al-N bonds are not detectable by 27Al MAS NMR until very late in the reaction (after 8 h firing at 1400 °C), and coincide with the appearance of the secondary product AlN. The implications for the carbothermal reaction sequence in kaolinite and halloysite are discussed.

Electronic Resource

0095-9898

Life and Medical Sciences ; Cell & Developmental Biology

Wiley InterScience Backfile Collection 1832-2000

Biology

Medicine

14 Ill.

Electronic Resource

0271-2091

air-conditioning unit ; k-∊ model ; Reynolds stress model ; Engineering ; Numerical Methods and Modeling

Wiley InterScience Backfile Collection 1832-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Details are given of a study to obtain experimental data in an idealized environment for the purpose of evaluating the corresponding computational predictions and which supplement parallel measurements made in actual packaged air-conditioning units. The system consisted of a purpose-built low-speed wind tunnel with a working section constructed to reproduce particular features of the real units. In the experiment, both the mean velocity profiles and turbulence properties of the flow are obtained from triple-hot-wire anemometry measurements. A numerical model, based on finite volume methodology, was used to obtain the solution of the Reynolds-averaged Navier-Stokes equations for incompressible isothermal flow. The Reynolds stress terms in the equations are calculated using the standard k-∊ model and second-moment closure (Reynolds stress) models. The accuracy of the two models was evaluated against the experimental measurements made 10 mm downstream of a baffle. The results show that the standard k-∊ model gave the better agreement except in regions of strong recirculation. © 1997 John Wiley & Sons, Ltd.

13 Ill.

Electronic Resource