980 research outputs found
Comment on "Drip Paintings and Fractal Analysis", arXiv:0710.4917v2, by K. Jones-Smith, H. Mathur and L.M. Krauss
In a recent manuscript (arXiv:0710.4917v2), Jones-Smith et al. attempt to use
the well-established box-counting technique for fractal analysis to
"demonstrate conclusively that fractal criteria are not useful for
authentication". Here, in response to what we view to be an extremely
simplistic misrepresentation of our earlier work by Jones-Smith et al., we
reiterate our position regarding the potential of fractal analysis for artwork
authentication. We also point out some of the flaws in the analysis presented
in by Jones-Smith et al.Comment: Comment on arXiv:0710.4917v2 [cond-mat.stat-mech
3-manifolds which are spacelike slices of flat spacetimes
We continue work initiated in a 1990 preprint of Mess giving a geometric
parameterization of the moduli space of classical solutions to Einstein's
equations in 2+1 dimensions with cosmological constant 0 or -1 (the case +1 has
been worked out in the interim by the present author). In this paper we make a
first step toward the 3+1-dimensional case by determining exactly which closed
3-manifolds M^3 arise as spacelike slices of flat spacetimes, and by finding
all possible holonomy homomorphisms pi_1(M^3) to ISO(3,1).Comment: 10 page
Efficient Behavior of Small-World Networks
We introduce the concept of efficiency of a network, measuring how
efficiently it exchanges information. By using this simple measure small-world
networks are seen as systems that are both globally and locally efficient. This
allows to give a clear physical meaning to the concept of small-world, and also
to perform a precise quantitative a nalysis of both weighted and unweighted
networks. We study neural networks and man-made communication and
transportation systems and we show that the underlying general principle of
their construction is in fact a small-world principle of high efficiency.Comment: 1 figure, 2 tables. Revised version. Accepted for publication in
Phys. Rev. Let
Probing the Sensitivity of Electron Wave Interference to Disorder-Induced Scattering in Solid-State Devices
The study of electron motion in semiconductor billiards has elucidated our
understanding of quantum interference and quantum chaos. The central assumption
is that ionized donors generate only minor perturbations to the electron
trajectories, which are determined by scattering from billiard walls. We use
magnetoconductance fluctuations as a probe of the quantum interference and show
that these fluctuations change radically when the scattering landscape is
modified by thermally-induced charge displacement between donor sites. Our
results challenge the accepted understanding of quantum interference effects in
nanostructures.Comment: 8 pages, 5 figures, Submitted to Physical Review
Effect of resonant magnetic perturbations on low collisionality discharges in MAST and a comparison with ASDEX Upgrade
Sustained ELM mitigation has been achieved on MAST and AUG using RMPs with a
range of toroidal mode numbers over a wide region of low to medium
collisionality discharges. The ELM energy loss and peak heat loads at the
divertor targets have been reduced. The ELM mitigation phase is typically
associated with a drop in plasma density and overall stored energy. In one
particular scenario on MAST, by carefully adjusting the fuelling it has been
possible to counteract the drop in density and to produce plasmas with
mitigated ELMs, reduced peak divertor heat flux and with minimal degradation in
pedestal height and confined energy. While the applied resonant magnetic
perturbation field can be a good indicator for the onset of ELM mitigation on
MAST and AUG there are some cases where this is not the case and which clearly
emphasise the need to take into account the plasma response to the applied
perturbations. The plasma response calculations show that the increase in ELM
frequency is correlated with the size of the edge peeling-tearing like response
of the plasma and the distortions of the plasma boundary in the X-point region.Comment: 31 pages, 28 figures. This is an author-created, un-copyedited
version of an article submitted for publication in Nuclear Fusion. IoP
Publishing Ltd is not responsible for any errors or omissions in this version
of the manuscript or any version derived from i
Political Marketing Activity in Simultaneous Regional Elections 2015
Regional head election system was change in 2015. It has impact on political marketing strategy to all stake holders, such as political party and candidatures.The purposes of this research is to analyzeashifting ofpolitical marketing issueson regional election 2015. The research approach uses the mix method with the type of sequential explanatory. The subjects of this research are the candidates, election successful teams or supporting team, and young voters. Location of research based on cluster system district and sub district in Bandung, Cianjur, Magelang, Sleman, and Medan. The data are collected through techniques of questionnaires to young voters; interview to candidates, election successful teams and young voters, as well as the documentation of media and data on Regional General Elections Commission (KPUD). There are also triangular data techniqueinterviews with the General Elections Commission (KPU), the community and supporting team, and documentation and questionnaire form. The result shows that the system of political marketing has already started shifting from product, promotion, price, place, and people known as the 5Ps from mostly dominated by Political Partyinto the role of PEOPLE as candidature in influensing the voters. The Result also tells that shifting from using convetional media into almost using digital media was powerfull
First data and preliminary experimental results from a new Doppler Backscattering system on the MAST-U spherical tokamak
A new Doppler backscattering (DBS) system, consisting of Q-band and V-band,
has been installed and achieved its first data on the MAST-U spherical tokamak.
The Q-band and V-band have separate microwave source systems, but share the
same optical front-end components. The Q-band and V-band sources simultaneously
generate eight (34, 36, 38, 40, 42, 44, 46 and 48 GHz) and seven (52.5, 55,
57.5, 60, 62.5, 65 and 67.5 GHz) fixed frequency probe beams, respectively.
These frequencies provide a large range of radial positions from the
low-field-side edge plasma to the core, and possibly to the high-field-side
edge, depending on the plasma conditions. The quasi-optical system consists of
a remotely-tunable polarizer, a focusing lens and a remotely-steerable mirror.
By steering the mirror, the system provides remote control of the probed
density fluctuation wavenumber, and allow the launch angle to match the
magnetic field. The range of accessible turbulence wavenumbers (k_\theta) is
reasonably large with normalized wavenumber k_\theta\rho_s ranging from <0.5 to
9. The first data acquired by this DBS system is validated by comparing with
the data from the other DBS system on MAST-U (introduced in Ref. [21]). An
example of measuring the velocity profile spanning from the edge to the center
in a high-density plasma is presented, indicating the robust capabilities of
the integrated Q-band and V-band DBS systems
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The influence of remote aerosol forcing from industrialised economies on the future evolution of East and West African rainfall
Past changes in global industrial aerosol emissions have played a significant role in historical shifts in African rainfall and yet assessment of the impact on African rainfall of near term (10-40 year) potential aerosol emission pathways remains largely unexplored.
Whilst existing literature links future aerosol declines to a northward shift of Sahel rainfall, existing climate projections rely on RCP scenarios that do not explore the range of air quality drivers. Here we present projections from two emission scenarios that better envelope the range of potential aerosol emissions. More aggressive emission cuts results in northward shifts of the tropical rain-bands whose signal can emerge from expected internal variability on short, 10-20 year, time horizons. We also show for the first time that this northward shift also impacts East Africa, with evidence of delays to both onset and withdrawal of the Short Rains. However, comparisons of rainfall impacts across models suggest that only certain aspects of both the West and East African model responses may be robust, given model uncertainties.
This work motivates the need for wider exploration of air quality scenarios in the climate science community to assess the robustness of these projected changes and to provide evidence to underpin climate adaptation in Africa. In particular, revised estimates of emission impacts of legislated measures every 5-10 years would have a value in providing near term climate adaptation information for African stakeholders
Domain-Adversarial Learning for Multi-Centre, Multi-Vendor, and Multi-Disease Cardiac MR Image Segmentation
Cine cardiac magnetic resonance (CMR) has become the gold standard for the
non-invasive evaluation of cardiac function. In particular, it allows the
accurate quantification of functional parameters including the chamber volumes
and ejection fraction. Deep learning has shown the potential to automate the
requisite cardiac structure segmentation. However, the lack of robustness of
deep learning models has hindered their widespread clinical adoption. Due to
differences in the data characteristics, neural networks trained on data from a
specific scanner are not guaranteed to generalise well to data acquired at a
different centre or with a different scanner. In this work, we propose a
principled solution to the problem of this domain shift. Domain-adversarial
learning is used to train a domain-invariant 2D U-Net using labelled and
unlabelled data. This approach is evaluated on both seen and unseen domains
from the M\&Ms challenge dataset and the domain-adversarial approach shows
improved performance as compared to standard training. Additionally, we show
that the domain information cannot be recovered from the learned features.Comment: Accepted at the STACOM workshop at MICCAI 202
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