Search results for " dependence"
showing 10 items of 2018 documents
Assessing plant diversity and composition in grasslands across spatial scales: the standardised EDGG sampling methodology
2016
This paper presents the details of the EDGG sampling methodology and its underlying rationales. The methodology has been applied during EDGG Research Expeditions and EDGG Field Workshops since 2009, and has been subsequently adopted by various other researchers. The core of the sampling are the EDGG Biodiversity Plots, which are 100‐m2 squares comprising, in two opposite corners, nested‐plot series of 0.0001, 0.001, 0.01, 0.1, 1 and 10 m2 square plots, in which all terricolous vascular plants, bryophytes and lichens are recorded using the shoot presence method. In the 10‐m2 plots, species cover is also estimated as a percentage and various environmental and structural parameters are recorde…
Path Dependence of Power Relations, Path-Breaking Change and Technological Adaptation
2011
We study the path dependence of technological systems and power relations inside companies. While the existing literature suggests power relations and technology to be path dependent and influenced by each other, interactions across these evolutionary processes remain poorly understood. We studied the history of four retail firms over 40 years, applying event structure analysis to explicate key dynamics. Companies exhibited two episodes of converging path dependency, where power relations further increased technological inertia. In each case, power initially concentrated outside the central headquarters. Path-breaking change led all firms to centralize power and implement networked IT syste…
La dépendance automobile pour l’accès des ménages aux services : Le cas de la grande couronne francilienne
2007
The automobile dependence raises the question of social economic standard in mobility. In the outer suburbs of Paris, the automobile is the key element that determines the location of general services and the access of households to those services. Yet, this appreciation must be moderated according to territories and populations. Some territories depend less on the automobile, and part of households have developed an alternative system of mobility that partially compensates the absence or the low access to automobile equipment. If non motorized households remain socially marginalized because of the automobile dependence, the motorized households are not free from this risk either. Our obser…
First Measurement of the $Q^2$ Dependence of the Beam-Normal Single Spin Asymmetry for Elastic Scattering off Carbon
2018
We report on the first Q^{2}-dependent measurement of the beam-normal single spin asymmetry A_{n} in the elastic scattering of 570 MeV vertically polarized electrons off ^{12}C. We cover the Q^{2} range between 0.02 and 0.05 GeV^{2}/c^{2} and determine A_{n} at four different Q^{2} values. The experimental results are compared to a theoretical calculation that relates A_{n} to the imaginary part of the two-photon exchange amplitude. The result emphasizes that the Q^{2} behavior of A_{n} given by the ratio of the Compton to charge form factors cannot be treated independently of the target nucleus.
Modelling of natural synthetic polyelectrolyte interactions in natural waters by using SIT, Pitzer and Ion Pairing approaches
2006
Abstract In this paper SIT and Pitzer models are used for the first time to describe the interactions of natural and synthetic polyelectrolytes in natural waters. Measurements were made potentiometrically at 25 °C in single electrolyte media, such as Et 4 NI and NaCl (for fulvic acid 0.1 − 1 S single salt ” BA, with cation B and anion A representing all the major cations (Na + , K + , Mg 2+ , Ca 2+ ) and anions (Cl − , SO 4 2− ) in natural sea water, respectively. The ion pair formation model was also applied to fulvate and alginate in artificial sea water by examining the interaction of polyanions with the single sea water cation. Results were compared with those obtained from previous sp…
Vapor Pressures of Polymer Solutions and the Modeling of Their Composition Dependence
2009
Equilibrium vapor pressures, p, are reported for the systems tetrahydrofuran + poly(vinyl methyl ether) and tetrahydrofuran + polystyrene at 20, 40, and 60 °C. These data plus information from the literature serve to demonstrate that the composition dependence of p can be modeled quantitatively for polymer solutions in thermodynamically very different solvents by means of three, physically meaningful parameters.
Optical tweezing electrophoresis of isolated, highly charged colloidal spheres
2001
Abstract We report on a novel optical tweezing experiment measuring the electrophoretic mobility μ of highly charged spherical particles suspended in water at volume fractions Φ≤2×10 −7 . At deionised conditions μ =2.5×10 −8 m 2 V −1 s −1 , it decreases further upon increasing the salt concentration c . We compare our data to measurements at larger Φ, where generally much larger μ and a qualitatively different dependence on the salt concentration are observed. To characterise the dependence on Φ we performed measurements at no added salt. There the mobility increases in the unordered state but stays constant at μ =6.8×10 −8 m 2 V −1 s −1 as the system develops fluid order. In the ordered re…
Correlations of the nonexponentiality and state dependence of mechanical relaxations with bond connectivity in Ge-As-Se supercooled liquids
1992
We have studied the mechanical responses of supercooled Ge-As-Se liquids to flexural strains and temperature steps. The departures from exponential relaxation correlate well with the variations in connectivity. The structural state dependence of the mechanical relaxation, detected in pure and weakly cross-linked Se, is suppressed completely at the rigidity percolation threshold {l angle}{ital r}{sub {ital c}}{r angle}, where the liquid fragility is a minimum. The shapes of the decay functions of samples with the same {l angle}{ital r}{sub {ital c}}{r angle} but different compositions are not universal at {ital T}{sub {ital g}} probably because of chemical effects near the binary edges of th…
No-flow temperature and solidification in injection molding simulation
2011
The no‐flow temperature (NFT) is a parameter representing the rheological solidification temperature of a polymer. A polymer, during injection molding filling stage, can stop its flow because of its high viscosity, although it is not yet fully solidified by means of glass transition or crystallization. The NFT is used in most of injection molding simulation packages: with this simple parameter it is possible to reduce the errors deriving from viscosity extrapolation at relatively low temperatures. The viscosity measurements for polymers are usually carried out at high temperatures, and the viscosity models can fail in prediction at temperatures close to the glass transition or crystallizati…
Non linear viscoelasticity of polymeric liquids interpreted by means of a stress dependence of free volume
1977
Several existing data of non-linear viscoelasticity of amorphous polymers aboveT g are here interpreted by assuming that the free volume changes during the motion. Equations of a stress-temperature equivalence are suggested which favorably compare with the data. It is also shown that the volume variations are sufficiently small to have escaped observation.