84 research outputs found
Geometrical Dependence of High-Bias Current in Multiwalled Carbon Nanotubes
We have studied the high-bias transport properties of the different shells
that constitute a multiwalled carbon nanotube. The current is shown to be
reduced as the shell diameter is decreased or the length is increased. We
assign this geometrical dependence to the competition between electron-phonon
scattering process and Zener tunneling.Comment: 4 pages, 4 figure
Determination of the Intershell Conductance in Multiwalled Carbon Nanotubes
We report on the intershell electron transport in multiwalled carbon
nanotubes (MWNT). To do this, local and nonlocal four-point measurements are
used to study the current path through the different shells of a MWNT. For
short electrode separations 1 m the current mainly flows
through the two outer shells, described by a resistive transmission line with
an intershell conductance per length of ~(10 k\Omega)^{-1}/m. The
intershell transport is tunnel-type and the transmission is consistent with the
estimate based on the overlap between -orbitals of neighboring shells.Comment: 5 pages, 4 figure
Ab Initio Calculations of the Walls Shear Strength of Carbon Nanotubes
The dependence of the energy of interwall interaction in double-walled carbon
nanotubes (DWNT) on the relative position of walls has been calculated using
the density functional method. This dependence is used to evaluate forces that
are necessary for the relative telescopic motion of walls and to calculate the
shear strength of DWNT for the relative sliding of walls along the nanotube
axis and for their relative rotation about this axis. The possibility of
experimental verification of the obtained results is discussed.Comment: 4 pages, 1 figur
Graphene Transistor as a Probe for Streaming Potential
We explore the dependence of electrical transport in a graphene field effect
transistor (GraFET) on the flow of the liquid within the immediate vicinity of
that transistor. We find large and reproducible shifts in the charge neutrality
point of GraFETs that are dependent on the fluid velocity and the ionic
concentration. We show that these shifts are consistent with the variation of
the local electrochemical potential of the liquid next to graphene that are
caused by the fluid flow (streaming potential). Furthermore, we utilize the
sensitivity of electrical transport in GraFETs to the parameters of the fluid
flow to demonstrate graphene-based mass flow and ionic concentration sensing.
We successfully detect a flow as small as~70nL/min, and detect a change in the
ionic concentration as small as ~40nM.Comment: 6 pages, 4 figure
Accélération de la production de matériel "mélèze hybride" (2 ème tranche) : rapport d'activité 1992
This report is a summary of the results of experiments conducted in 1992 by the CEMAGREF to improve the production techniques of seeds and plants of hybrid larch (Larix eurolepis Henry). The projects covered four main topics: - floral induction, in orchards, in open-fields and on Japanese larch grown in containers - pollen harvesting including a detailed analysis of the performances of the harvesting machine, and the study on the influence of greenhouse environment on the production of the male strobiles and on pollen quality- artificial pollination - vegetative multiplication. / Ce rapport synthétise les résultats des recherches entreprises en 1992 par le CEMAGREF en vue d'améliorer les techniques de production de graines et de plants de Mélèze hybride (Larix eurolepis Henry). Les travaux concernent 4 grands thèmes : - l'induction florale, en verger de plein-champs et sur plants de mélèze du Japon élevés en conteneurs - la récolte de pollen incluant notamment une analyse détaillée des performances de la machine à récolter et l'étude de l'influence de l'environnement-serre sur la production des stroliles mâles et sur la qualité du pollen - la pollinisation artificielle - la multiplication végétative en vrac
Vocal response times to real and imagined stimuli in spatial neglect: A group study and single-case report
The relationships between spatial neglect for perceptual objects and representational for imagined items are difficult to explore because of several methodological problems, including the dearth of comparable tests for real and imagined scenes. We asked 19 patients with right brain damage and 12 healthy controls to say whether an auditorily presented French geographical location was left or right of Paris, and recorded their vocal response times. Afterwards, participants performed a similar test with visually presented items. Although several patients had asymmetries of performance on the perceptual version of the test, only one patient was more accurate for right-sided than for left-sided imagined stimuli, thus showing evidence for imaginal neglect. However, this patient performed normally on place description and on mental number line bisection, perhaps as a consequence of different strategies he employed for these tasks. Overall, our results confirm previous evidence showing that imaginal neglect is less frequent than, and often occurs in association with, perceptual neglect. Imaginal neglect may result from the contribution of deficits partly distinct from those implicated in perceptual neglect, such as impaired endogenous orienting of attention or deficits of spatial working memory
Acceleration de la production de materiel 'meleze hybride' (3eme tranche) : rapport d'activite 1993
SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : GR 1179 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
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