25,161 research outputs found
Transport in random quantum dot superlattices
We present a novel model to calculate single-electron states in random
quantum dot superlattices made of wide-gap semiconductors. The source of
disorder comes from the random arrangement of the quantum dots (configurational
disorder) as well as spatial inhomogeneities of their shape (morphological
disorder). Both types of disorder break translational symmetry and prevent the
formation of minibands, as occurs in regimented arrays of quantum dots. The
model correctly describes channel mixing and broadening of allowed energy bands
due to elastic scattering by disorder
Can Local Food Go Mainstream?
Local Food, Relocalization, Supermarket, Distribution Center, Economies of Size, Transportation Efficiency, Food Consumption/Nutrition/Food Safety, Marketing,
Pilot3 D7.1 - Dissemination, communication and exploitation plan
This document is the Communication, Dissemination and Exploitation Plan (D7.1) of the Clean Sky 2 Innovation Action Pilot3. The document defines the communication and dissemination actions to be performed during the project, and the potential exploitation of the project results. A complete strategy of communication is presented, as well as the items and content already prepared for it
Tight coupling in thermal Brownian motors
We study analytically a thermal Brownian motor model and calculate exactly
the Onsager coefficients. We show how the reciprocity relation holds and that
the determinant of the Onsager matrix vanishes. Such condition implies that the
device is built with tight coupling. This explains why Carnot's efficiency can
be achieved in the limit of infinitely slow velocities. We also prove that the
efficiency at maximum power has the maximum possible value, which corresponds
to the Curzon-Alhborn bound. Finally, we discuss the model acting as a Brownian
refrigerator
Dispatcher3 D7.1 - Project communication, dissemination and exploitation plan
This document is the Communication, Dissemination and Exploitation Plan (D7.1) of the Clean Sky 2 Innovation Action Dispatcher3. The document defines the communication and dissemination actions to be performed during the project, and the potential exploitation of the project results. A complete strategy of communication is presented, as well as the items and content already prepared for it
Resolving Molecular Line Emission from Protoplanetary Disks: Observational Prospects for Disks Irradiated by Infalling Envelopes
Molecular line observations that could resolve protoplanetary disks of ~100
AU both spatially and kinematically would be a useful tool to unambiguously
identify these disks and to determine their kinematical and physical
characteristics. In this work we model the expected line emission from a
protoplanetary disk irradiated by an infalling envelope, addressing the
question of its detectability with subarcsecond resolution. We adopt a
previously determined disk model structure that gives a continuum spectral
energy distribution and a mm intensity spatial distribution that are consistent
with observational constraints of HL Tau. An analysis of the capability of
presently working and projected interferometers at mm and submm wavelengths
shows that molecular transitions of moderate opacity at these wavelengths
(e.g., C17O lines) are good candidates for detecting disk lines at subarcsecond
resolution in the near future. We suggest that, in general, disks of typical
Class I sources will be detectable.Comment: 41 pages, 16 figures. To be published in The Astrophysical Journa
On the kinematic detection of accreted streams in the Gaia era: a cautionary tale
The CDM cosmological scenario predicts that our Galaxy should
contain hundreds of stellar streams at the solar vicinity, fossil relics of the
merging history of the Milky Way and more generally of the hierarchical growth
of galaxies. Because of the mixing time scales in the inner Galaxy, it has been
claimed that these streams should be difficult to detect in configuration space
but can still be identifiable in kinematic-related spaces like the
energy/angular momenta spaces, E-Lz and Lperp-Lz, or spaces of orbital/velocity
parameters. By means of high-resolution, dissipationless N-body simulations,
containing between 25 and 35 particles, we model the
accretion of a series of up to four 1:10 mass ratio satellites then up to eight
1:100 satellites and we search systematically for the signature of these
accretions in these spaces. In all spaces considered (1) each satellite gives
origin to several independent overdensities; (2) overdensities of multiple
satellites overlap; (3) satellites of different masses can produce similar
substructures; (4) the overlap between the in-situ and the accreted population
is considerable everywhere; (5) in-situ stars also form substructures in
response to the satellite(s) accretion. These points are valid even if the
search is restricted to kinematically-selected halo stars only. As we are now
entering the 'Gaia era', our results warn that an extreme caution must be
employed before interpreting overdensities in any of those spaces as evidence
of relics of accreted satellites. Reconstructing the accretion history of our
Galaxy will require a substantial amount of accurate spectroscopic data, that,
complemented by the kinematic information, will possibly allow us to
(chemically) identify accreted streams and measure their orbital properties.
(abridged)Comment: Accepted on A&A. A high-resolution version of the paper is available
at http://aramis.obspm.fr/~paola/ELZ/Elz.pd
Engage D3.7 Update on the Engage repository and knowledge hub functionality (initial)
This initial report describes the planned functionality and features of the forthcoming Engage wiki and establishes the scope of the ATM concepts roadmap
Space VLBI Observations of 3C371
We present the first space VLBI observations of 3C~371, carried out at a
frequency of 4.8 GHz. The combination of the high resolution provided by the
orbiting antenna Highly Advanced Laboratory for Communications and Astronomy
(HALCA) and the high sensitivity of the VLBA allows imaging of the jet of
3C~371 with an angular resolution of approximately 0.26 mas, which for this
relatively nearby source corresponds to 0.4 h pc. Comparison
between two epochs separated by 66 days reveals no apparent motions in the
inner 7 mas jet structure above an upper limit of c. This
value, the absence of detectable counterjet emission from the presumably
symmetric jet, plus the presence of extended double-lobe structure, are
consistent with the knots in the jet being stationary features such as standing
shocks. The jet intensity declines with the angular distance from the core as
. This is more gradual than that derived for 3C~120,
, for which there is evidence for strong intereactions between
the jet and ambient medium. This suggests that in 3C~371 there is a greater
level of {\it in situ} acceleration of electrons and amplification of magnetic
field. We interpret sharp bends in the jet at sites of off-center knots as
further evidence for the interaction between the jet and external medium, which
may also be responsible for the generation of standing recollimation shocks.
These recollimation shocks may be responsible for the presumably stationary
components. The radio properties of 3C~371 are intermediate between those of
other radio galaxies with bright cores and those of BL Lacertae objects.Comment: 5 pages, 4 figures. Accepted for publication in Ap
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