2,204 research outputs found
A Graphene Field-Effect Device
In this letter, a top-gated field effect device (FED) manufactured from
monolayer graphene is investigated. Except for graphene deposition, a
conventional top-down CMOS-compatible process flow is applied. Carrier
mobilities in graphene pseudo-MOS structures are compared to those obtained
from top-gated Graphene-FEDs. The extracted values exceed the universal
mobility of silicon and silicon-on-insulator MOSFETs.Comment: 12 pages, 3 figure
On the effects of regional accents on memory and credibility
The information we obtain from how speakers sound—for example their accent—affects how we interpret the messages they convey. A clear example is foreign accented speech, where reduced intelligibility and speaker's social categorization (out-group member) affect memory and the credibility of the message (e.g., less trust- worthiness). In the present study, we go one step further and ask whether evaluations of messages are also affected by regional accents—accents from a different region than the listener. In the current study, we report results from three experiments on immediate memory recognition and immediate credibility assessments as well as the illusory truth effect. These revealed no differences between messages conveyed in local—from the same region as the participant—and regional accents—from native speakers of a different country than the partici- pants. Our results suggest that when the accent of a speaker has high intelligibility, social categorization by accent does not seem to negatively affect how we treat the speakers' messages
Structure of the Local-field factor of the 2-D electron fluid. Possible evidence for correlated scattering of electron pairs
The static local-field factor (LFF) of the 2-D electron fluid is calculated
{\it nonperturbatively} using a mapping to a classical Coulomb fluid
Phys. Rev. Lett., {\bf 87}, 206. The LFF for the paramagnetic
fluid {\it differs markedly} from perturbation theory where a maximum near
2 is expected. Our LFF has a quasi-linear small-k region leading to a
maximum close to 3, in agreent with currently available quantum Monte
Carlo data. The structure in the LFF and its dependence on the density and
temperature are interpretted as a signature of correlated scattering of
electron pairs of opposite spin.The lack of structure at implies
weakened Friedel oscillations, Kohn anomalies etc.Comment: 4 pages, 3 figures, version 2 of condmat/0304034, see
http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc/ Changs in the text, figure 2
and updated reference
Spin-polarized stable phases of the 2-D electron fluid at finite temperatures
The Helmholtz free energy F of the interacting 2-D electron fluid is
calculated nonperturbatively using a mapping of the quantum fluid to a
classical Coulomb fluid [Phys. Rev. Letters, vol. 87, 206404 (2001)]. For
density parameters rs such that rs<~25, the fluid is unpolarized at all
temperatures t=T/EF where EF is the Fermi energy. For lower densities, the
system becomes fully spin polarized for t<~0.35, and partially polarized for
0.35<t< 2, depending on the density. At rs ~25-30, and t ~0.35, an ''ambispin''
phase where F is almost independent of the spin polarization is found. These
results support recent claims, based on quantum Monte Carlo results, for a
stable, fully spin-polarized fluid phase at T = 0 for rs larger than about
25-26.Comment: Latex manuscript (4-5 pages) and two postscript figures; see also
http://nrcphy1.phy.nrc.ca/ims/qp/chandre/chnc
Overview of Kyoto Fusioneering’s SCYLLA© (“Self-Cooled Yuryo Lithium-Lead Advanced”) Blanket for Commercial Fusion Reactors
This article outlines Kyoto Fusioneering’s (KF’s) initial engineering and development activities for its self-cooled lithium lead-type blanket: Self-Cooled Yuryo Lithium-Lead Advanced (SCYLLA©). We provide details on overall design, including an initial tritium breeding ratio (TBR) assessment via neutronics analysis, as well as the status of SCYLLA©-relevant R&D. This includes silicon carbide composite (SiCf/SiC) manufacturing techniques, tritium extraction, materials compatibility, and heat transfer, which are being explored via collaboration with Kyoto University. Results of previous work in relation to this R&D are presented. Permeability coefficients indicate a promising property of SiCf/SiC tritium hermeticity at high temperatures. Tritium extraction technology via vacuum sieve tray (VST) is shown to be demonstrated at engineering scale. A local TBR of up to 1.4 can be achieved with the SCYLLA© configuration. Fabrication methods for various SiCf/SiC components including the blanket module, heat exchanger, and flow path components are provided. A tritium compatible high-temperature SiCf/SiC heat exchanger is discussed. Commercial viability and reactor adaptability are considered as a theme throughout. Finally, KF’s plans to build a facility for demonstration reactor relevant testing of a SCYLLA© prototype in the mid-2020s, which will provide a significant step toward commercial fusion energy, are presented
Maximum illumination control system for photovoltaic panels orientation
The article describes the solar tracker for photovoltaic panels and energy systems based on such devices. The authors introduce the results of calculations of the solar tracker application effectiveness for solar energy systems and the results of the field testing in Tomsk
Measuring the equation of state of a hard-disc fluid
We use video microscopy to study a two-dimensional (2D) model fluid of
charged colloidal particles suspended in water and compute the pressure from
the measured particle configurations. Direct experimental control over the
particle density by means of optical tweezers allows the precise measurement of
pressure as a function of density. We compare our data with theoretical
predictions for the equation of state, the pair-correlation function and the
compressibility of a hard-disc fluid and find good agreement, both for the
fluid and the solid phase. In particular the location of the transition point
agrees well with results from Monte Carlo simulations.Comment: 7 pages, to appear in EPL, slightly corrected versio
The one-component plasma: a conceptual approach
The one-component plasma (OCP) represents the simplest statistical mechanical
model of a Coulomb system. For this reason, it has been extensively studied
over the last forty years. The advent of the integral equations has resulted in
a dramatic improvement in our ability to carry out numerical calculations, but
came at the expense of a physical insight gained in a simpler analytic theory.
In this paper we present an extension of the Debye-Hueckel (DH) theory to the
OCP. The theory allows for analytic calculations of all the thermodynamic
functions, as well as the structure factor. The theory explicitly satisfies the
Stillinger-Lovett and, for small couplings, the compressibility sum rules,
implying its internal self consistency.Comment: 28 pages, 5 Postscript figures, uses elsart.sty, accepted for
publication in Physica
Description of Atmospheric Conditions at the Pierre Auger Observatory Using Meteorological Measurements and Models
Atmospheric conditions at the site of a cosmic ray observatory must be known
well for reconstructing observed extensive air showers, especially when
measured using the fluorescence technique. For the Pierre Auger Observatory, a
sophisticated network of atmospheric monitoring devices has been conceived.
Part of this monitoring was a weather balloon program to measure atmospheric
state variables above the Observatory. To use the data in reconstructions of
air showers, monthly models have been constructed. Scheduled balloon launches
were abandoned and replaced with launches triggered by high-energetic air
showers as part of a rapid monitoring system. Currently, the balloon launch
program is halted and atmospheric data from numerical weather prediction models
are used. A description of the balloon measurements, the monthly models as well
as the data from the numerical weather prediction are presented
Construction of the free energy landscape by the density functional theory
On the basis of the density functional theory, we give a clear definition of
the free energy landscape. To show the usefulness of the definition, we
construct the free energy landscape for rearrangement of atoms in an FCC
crystal of hard spheres. In this description, the cooperatively rearranging
region (CRR) is clealy related to the hard spheres involved in the saddle
between two adjacent basins. A new concept of the simultaneously rearranging
region (SRR) emerges naturally as spheres defined by the difference between two
adjacent basins. We show that the SRR and the CRR can be determined explicitly
from the free energylandscape.Comment: 11 pages, 3 figures, submitted to J. Chem. Phy
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