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  • 1
    Electronic Resource
    Electronic Resource
    Two algebraic properties of thermal quantum field theories (1999)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 6234-6244 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We establish the Schlieder and the Borchers property for thermal field theories. In addition, we provide some information on the commutation and localization properties of projection operators. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.533089
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  • 2
    Electronic Resource
    Electronic Resource
    Viscosity dependence and solvent effects in the photoisomerization of cis-stilbene: Insight from a molecular dynamics study with an ab initio potential-energy function (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 8987-8999 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular-dynamics simulations of the photoisomerization of cis-stilbene in supercritical argon were performed. The stilbene molecule is represented by ab initio quantum chemistry, while the solvent, the interaction with solvent, and the time evolution were described by classical mechanics. Reaction rate constants are estimated and their dependence on temperature, pressure, and viscosity are investigated. Agreement with available experimental data was obtained. Our simulations strongly suggest a minimum on the excited-state potential-energy surface at a gauche conformation which is very rapidly reached after excitation, which leads to nonequilibrium barrier transitions. Specific solvent effects were identified. Implications on the current opinion on stilbene photoisomerization are discussed. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480242
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation with an ab initio potential energy function and finite element interpolation: The photoisomerization of cis-stilbene in solution (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 8773-8781 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An interpolation scheme for potential energy surfaces is presented. It employs a regular grid and finite element interpolation. The aim is the reduction of the computational expense for molecular dynamics simulation with a quantum chemical potential energy function. The methods used are described in detail. The feasibility is demonstrated and the efficiency and accuracy are evaluated for the photoisomerization of cis-stilbene in supercritical argon, using an ab initio configuration- interaction treatment for the first electronically excited state of the stilbene molecule and classical force fields for the solvent–solute interactions (quantum mechanical/molecular mechanical molecular dynamics). The number of required quantum chemical calculations of energy and gradients was substantially reduced compared to a simulation not using the interpolation scheme. On the other hand, the impact on the accuracy is insignificant. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475397
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  • 4
    Electronic Resource
    Electronic Resource
    Alpine newts (Triturus alpestris) as top predators in a high-altitude karst lake: daily food consumption and impact on the copepod Arctodiaptomus alpinus (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 33 (1995), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Population dynamics and feeding ecology of adult and larval alpine newts (Triturus alpestris, Laurenti) were investigated in a high-altitude karts lake to estimate their feeding pressure on the copepod Arctodiaptomus alpinuf (Imhof). Estimates of population size for reproducing adults ranged from 666 to 864 individuals in the lake during July and August. Total abundance of larvae before the onset of ice cover varied considerably between 4400 and 25400 individuals in different years.2. Arctodiaptomus alpinus was an important prey item for adult and larval alpine newts. During the second half of their aquatic period, adult newts moved to deeper water where the copepod reached its highest densities near the sediment. Adults and larvae exhibited no periodic feeding pattern. The feeding rhythm was more synchronized among the larvae than among the adults.3. Daily food consumption, estimated using the Elliott & Persson (1978) model, reached 4–21 mg dry biomass in adults. The daily ration of larvae was about 7% of body dry weight in the temperature range 6-11°C. Compared to published estimates of daily food consumption in salmonid fishes, the feeding pressure of newts appears low.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1995.tb00385.x
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  • 5
    Electronic Resource
    Electronic Resource
    Nitrate leaching: modifying the loss from mineralized organic matter (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 49 (1998), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The impact on nitrate leaching of agronomic practices designed to immobilize nitrogen in autumn and winter was investigated over 4 years. Experimental treatments (reducing tillage depth, incorporating harvest residues, reducing fertilizer N by growing unfertilized grass or by spring-sown rather than autumn-sown crops) were compared with a control treatment in which autumn crops were sown after burning harvest residues, mouldboard ploughing and seedbed preparation. Winter cover cropping was also compared with winter fallowing. In the first year, incorporation of harvest residues or reducing tillage depth significantly decreased nitrate leaching compared with the control. Unfertilized grass did not affect leaching in the first winter but significantly decreased it in years 2 and 3. When winter cover crops were grown, nitrate leaching was never less than that under an autumn-sown cereal, and in the subsequent year leaching could be significantly greater. Winter fallowing caused the most nitrate leaching over the year. In the winter following a spring-sown crop, leaching under an autumn-sown crop greatly increased. Summed over 4 years, most leaching occurred with the winter fallow—spring cropping treatment; it was 18% more than where a winter cover crop preceded the spring crop. Reducing tillage depth or incorporating harvest residues did not significantly decrease leaching. Unfertilized grass ley followed by an autumn-sown cereal in the fourth year was the only treatment that significantly decrease leaching. Unfertilized grass ley followed by an autumn-sown cereal in the fourth year was the only treatment that significantly reduced leaching loss compared with the control. Incorporating harvest residues resulted in a balance between annual N inputs and outputs. All other treatments required substantial net annual N mineralization to balance annual inputs and outputs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1998.4940649.x
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  • 6
    Electronic Resource
    Electronic Resource
    Pharmacological Activity and Membrane Interactions of Antiarrhythmics: 4D-QSAR/QSPR Analysis (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 303-311 
    Details
    ISSN: 1573-904X
    Keywords: antiarrhythmics ; molecular dynamics ; partial least squares regression ; genetic function approximation ; quantitative structure-activity relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. This study was done to explore the relationships of both macroscopic and molecular level physicochemical properties to in-vivo antiarrhythmic activity and interactions with phospholipid membranes for a set of cationic-amphiphilic analogs. Methods. The 4D-QSAR method, recently developed by Hopfinger and co-workers (1), was employed to establish 3D-QSAR/QSPR models. Molecular dynamics simulations provided the set of conformational ensembles which were analyzed using partial least squares regression in combination with the Genetic Function Approximation algorithm to construct QSAR and QSPR models. Results. Significant QSAR models for in-vivo antiarrhythmic activity were constructed in which logP (the partition coefficient), and specific grid cell occupancy (spatial) descriptors are the main activity correlates. LogP is the most significant QSAR descriptor. 4D-QSPR models were also developed for two analog-membrane interaction properties, the change in a membrane transition temperature and the ability of the analogs to displace adsorbed Ca2+-ions from phosphatidylserine mono-layers. Conclusions. Spatial features, represented by grid cell occupancy descriptors, supplement partition coefficient, which is the most important determinant of in-vivo antiarrhythmic activity, to provide a comprehensive model for drug action. The QSPR models are less significant in statistical measures, and limited to interpretation of possible molecular mechanisms of action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011983005813
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  • 7
    Electronic Resource
    Electronic Resource
    A solid-state NMR study of cellulose degradation (1996)
    Springer
    Cellulose 3 (1996), S. 77-90 
    Details
    ISSN: 1572-882X
    Keywords: solid-state NMR ; cellulose degradation ; magic-angle spinning ; power transformers ; insulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A series of laboratory-aged transformer insulating papers were investigated using solid-state NMR spectroscopy. Carbon-13 CPMAS, and proton MAS experiments were carried out along with static proton relaxation (T1, and T1ρ) and free induction decay (FID) measurements. Some proton CRAMPS and proton-carbon-13 correlation (WISE) experiments were also undertaken. A change in the proton T1 and FID with ageing was detected. No detectable change was found in the proton T1ρ. Some amorphous cellulose was detected in the carbon-13 spectrum. There was, however, no evidence for a substantial change in the nature of the cellulose with ageing. The carbon-13 spectra from some aged samples showed signals not present in the spectrum from an unaged sample. This was taken to be evidence of chemical degradation. Proton MAS and the WISE exeriment gave some information about the nature of the water in the sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02228792
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  • 8
    Electronic Resource
    Electronic Resource
    Modeling and Characterization of the 3rd Order Charge-Pump PLL: a Fully Event-driven Approach (1999)
    Springer
    Analog integrated circuits and signal processing 19 (1999), S. 25-45 
    Details
    ISSN: 1573-1979
    Keywords: Charge-Pump Phase-Locked Loop ; mixed-mode circuits ; event-driven behavioral simulation ; non-linear dynamics ; chaos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this paper, the event-driven concept is applied to the third order Charge-Pump Phase-Locked Loop (CP-PLL) and leads to the description of a behavioral model based on a set of exact and non-linear recursive equations. A simulator (SIMPLL), written in C and using this model, checks the conventional z-domain approximate stability theory and brings to the fore the strongly non-linear nature of the CP-PLL that a careful and safe design must take into account. Thus, in order to have a more exhaustive design characterization, a statistical analysis method is explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008326315191
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  • 9
    Electronic Resource
    Electronic Resource
    Dicranophoridae (Rotifera) from the Alps (1998)
    Springer
    Hydrobiologia 387-388 (1998), S. 63-77 
    Details
    ISSN: 1573-5117
    Keywords: Dicranophoridae ; Austria ; alpine water bodies ; taxonomy ; biogeography ; ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rotifera of the family Dicranophoridae Harring, 1913 were recorded from mountainous altitudes of the Austrian Alps. Here, their morphology, distribution and ecology is detailed. The description of Encentrum walterkostei Jersabek is amended by observations on living animals. Of 19 species encountered, all but four are new to the alpine region, nine species are first records for the biogeographic region 'Alps'. Four species are new to science and will be published elsewhere. The majority are cosmopolites or widely distributed taxa, but also species with a more limited range, possibly endemics, seem to exist. Most species can be characterized as being more commonly found in cold environments, some of them are known to be psammobiontic or psammophilic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017017120656
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  • 10
    Electronic Resource
    Electronic Resource
    Three-dimensional endoluminal ultrasound (1997)
    Springer
    Diseases of the colon & rectum 40 (1997), S. 47-50 
    Details
    ISSN: 1530-0358
    Keywords: Rectal cancer ; Ultrasound ; Three-dimensional ; Image processing ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study was designed to evaluate the application of three-dimensional (3D) transrectal ultrasound (TRUS) in diagnostics, staging, and treatment planning of rectal cancer. METHOD: Transversal images, generated during conventional TRUS examination, are recorded by means of a specially designed computer-based system to obtain a 3D array of slices, covering the whole region of interest. Different structures (normal or pathologically affected) are segmented, isolated, and rendered using the tools of the system to produce a realistic spatial view of investigated organs. Dynamic movies are also generated and replayed for better realization of spatial interrelations of studied objects. RESULTS: Nineteen patients (18 with rectal cancer and 1 who was healthy) have been examined. In 15 patients, full 3D TRUS reconstruction was performed. Results are illustrated with several examples from the studied group. CONCLUSION: We consider 3D TRUS a useful add-on to conventional TRUS. It may significantly improve understanding of the interrelation between normal and pathologic structures and help to exact preoperative staging and treatment planning of rectal carcinoma patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02055681
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