Search Results - (Author, Cooperation:A. Fuchs)

2018-02-28

National Academy of Sciences

0027-8424

1091-6490

Biology

Medicine

Natural Sciences in General

2018-01-12

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Genetics, Microbiology

2014-04-26

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

*Alternative Splicing ; Arabidopsis/*genetics/metabolism ; Arabidopsis Proteins/genetics/metabolism ; Cell Nucleus/genetics ; Chloroplasts/*metabolism ; Circadian Clocks ; Dibromothymoquinone/pharmacology ; Diuron/pharmacology ; Electron Transport/drug effects ; *Gene Expression Regulation, Plant ; Light ; Models, Biological ; Oxidation-Reduction ; Photosynthesis/drug effects ; Plant Leaves/metabolism ; Plant Roots/metabolism ; Plants, Genetically Modified ; Plastoquinone/*metabolism ; RNA Stability ; RNA, Messenger/genetics/metabolism ; RNA, Plant/genetics/metabolism ; Seedlings/genetics/metabolism ; Signal Transduction

2018-03-28

The American Society for Microbiology (ASM)

0066-4804

1098-6596

Biology

Medicine

2018-05-15

Nature Publishing Group (NPG)

2045-2322

Natural Sciences in General

2018-11-02

American Physical Society (APS)

1098-0121

1095-3795

Physics

Magnetism

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Clusters made of several hundreds of SF6 molecules are produced in the free jet expansion of a Ne–SF6 mixture and studied by electron diffraction methods. Cold clusters have the monoclinic structure which has been identified recently in a polycrystalline sample at and below 85 K. Clusters adopt the body centered cubic structure of the bulk plastic phase when they are warmed up after crossing the frontal shock wave. Diffraction patterns show a progressive evolution, particularly in several line heights, from the low to the high temperature structure. In order to account for these intermediate states, a 512-molecule cluster is simulated by molecular dynamics on the DAP computer, using a rigid-molecule model with a single Lennard-Jones atom–atom potential. Warming up the model from 50 to 160 K by steps of 5 K, it is found that the structural transition occurs between 90 and 120 K. Calculated diffraction functions are in very good agreement with experimental patterns for both crystalline structures and for the intermediate stages. Intermediate experimental patterns can thus be attributed to the evolution of single clusters rather than to the coexistence of clusters with different structures. According to the model, the high temperature structure is initiated by surface molecules, which suggests that a surface effect is responsible for the temperature spread of the transition.

Electronic Resource

1471-0528

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Summary. The concentrations of 13,14-dihydro-15-keto-prostaglandin F2α (PGFM) and oxytocin were measured by radioimmunoassay in the peripheral plasma of 21 women with low Bishop scores in whom cervical ripening and labour were induced with a cervical cap containing 1.5 mg of prostaglandin (PG) E2, left in place for 6 h. Blood samples were taken before and at 3, 6, 9 and 24 h after the cap was applied. Four women (control group) had a cap without PGE2. Labour began in 13 women receiving PGE2, 12 of whom were delivered within 24 h. In these women plasma PGFM rose progressively to levels seen during spontaneous labour, paralleling the changes in cervical dilatation. The increase became significant at 6 h, when cervical dilatation was 4.5 cm (SEM 0.5). Plasma oxytocin also increased significantly while the cap was in place and then decreased. Plasma PGFM and oxytocin did not change in the control subjects, and in the eight women needing further induction of labour the initial rises were transient and not statistically significant.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

A thin semiconducting NiO film is exposed to NO2 at room temperature. This exposure causes a work function change at the surface of the film due to adsorption of the NO2 molecules. It is found that there is a strong dependence of the adsorptivity, i.e., the amount of work function change per unit time, on the magnitude of an electrical field that is applied perpendicular to the film surface. This induced adsorptivity change is known as the electroadsorptive effect. In order to modulate the adsorptivity significantly, the electrical field strength must exceed 104 V/cm. This requirement can be achieved by using hybrid suspended gate field effect transistors with an air gap height below 1 μm. © 1998 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

In this paper, the structure of CO2 clusters made of less than a hundred of molecules is studied by means of electron diffraction experiments and molecular dynamics simulations. According to previous works, CO2 clusters are expected to undergo a transition in this size range, from an icosahedral structure to the bulk cubic structure. Electron diffraction patterns have been recorded from clusters produced in a free jet expansion of gaseous CO2. These patterns provide evidence of a structural change occurring in clusters made of a few tens of molecules. (CO2)N models, with 13〈N〈80, have been constructed in the cubic structure and annealed through a molecular dynamics calculation. Calculated diffraction functions show significant changes for a critical size of about 30 molecules per cluster. In the N=25 model, carbon atoms exhibit a polyicosahedral arrangement, similar to the one already identified in argon cluster models. In the N=32 model, most of the molecules build up a cubic lattice, meanwhile some of them adopt a pentagonal arrangement allowing a higher cluster stability. In addition to what has been observed previously, the present study confirms that the transformation from an icosahedral to a crystalline structure is a general process which occurs during the growth of van der Waals clusters made of small molecules. The relation between the critical size and the molecular species is briefly discussed. © 1996 American Institute of Physics.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Results of new simulations for n-butane, n-decane, n-hexadecane, and 2-methylbutane at different state points for seven different united atom interaction potential models are presented. The different models are evaluated with respect to the criteria simplicity, transferability, property independence, and state independence. Viscosities are increasingly underestimated (up to 80%) and diffusion coefficients are overestimated (up to 250%) as the density increases and temperature decreases. Clear evidence was found that the torsion potential is more important at high packing fractions and for longer chains. The comparison of transport coefficients is argued to be a measure of "goodness" of the interaction potential models resulting in a ranking of the models. © 2000 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The Green-Kubo formalism for evaluating transport coefficients by molecular dynamics has been applied to multicomponent mixtures of flexible, multicenter models of linear and branched alkanes and nitrogen and helium in the gas phase and in the liquid phase. Simulation results on binary systems are summarized and trends in prediction using simple but realistic molecular models are shown. New simulation results of N2–n-pentane agree with experiment with a maximum deviation of 36%, the greatest error being for pure n-pentane. Methodological aspects of simulating multicomponent systems with trace components are studied, varying the system size and molecular interaction potentials. It is shown that mixtures are treated representatively even when only one to two molecules of a species are present in the simulated system, unless there is an extreme degree of self-association. It is demonstrated that molecular dynamics may predict quantitatively (7% and 11% deviation) the viscosity of a seven component "synthetic" natural gas. © 1999 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

The Green-Kubo formalism for evaluating transport coefficients by molecular dynamics has been applied to flexible, multicenter models of linear and branched alkanes in the gas phase and in the liquid phase from ambient conditions to close to the triple point. The effects of integration time step, potential cutoff and system size have been studied and shown to be small compared to the computational precision except for diffusion in gaseous n-butane. The RATTLE algorithm is shown to give accurate transport coefficients for time steps up to a limit of 8 fs. The different relaxation mechanisms in the fluids have been studied and it is shown that the longest relaxation time of the system governs the statistical precision of the results. By measuring the longest relaxation time of a system one can obtain a reliable error estimate from a single trajectory. The accuracy of the Green-Kubo method is shown to be as good as the precision for all states and models used in this study even when the system relaxation time becomes very long. The efficiency of the method is shown to be comparable to nonequilibrium methods. The transport coefficients for two recently proposed potential models are presented, showing deviations from experiment of 0%–66%. © 1999 American Institute of Physics.

Electronic Resource

1095-8649

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Treatment of goldfish (Carassius auratus) with sub-lethal concentrations of an anionic detergent sodium lauryl sulphate for 1, 2 or 4 weeks produced histological changes in the interrenal (steroidogenic) cells of the head kidney which are indicative of a cellular activation. Significant increases in both the nuclear diameter of these cells and the number of nucleoli contained in the nuclei occurred after 1 week's treatment, although these effects were more pronounced after 2 and 4 weeks. There were little associated alterations in chromaffin cell activity. Preliminary experiments with another pollutant, zinc sulphate, suggest that it exerts a similar action to sodium lauryl sulphate on the interrenal cells. It is suggested the increases in corticosteroid production which occur after exposure of fish to sub-lethal concentrations of pollutants may be important in the development of a generalized disease syndrome and to the long-term success of fish populations.

Electronic Resource

0003-2697

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Electronic Resource

0006-291X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] That animals and humans can accomplish the same goal using different effectors and different goals using the same effectors attests to the remarkable flexibility of the central nervous system. This phenomenon has been termed ‘motor equivalence’,, an example being the writing of a ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] In the course of an investigation on levan-synthe- sizing bacteria, colloidal solutions of levan in distilled water were regularly stored in the icebox at 2 C. Some of these solutions were found to have become infected by organisms, apparently capable of using levan as sole source of carbon. After ...

Electronic Resource