703,579 research outputs found
Causal Dynamics of Discrete Surfaces
We formalize the intuitive idea of a labelled discrete surface which evolves
in time, subject to two natural constraints: the evolution does not propagate
information too fast; and it acts everywhere the same.Comment: In Proceedings DCM 2013, arXiv:1403.768
Let\u27s Clean Up Fashion 2009- The State of Pay Behind the UK High Street
The report provides detailed information on brands and retailers in the UK market, looking at the wages paid to garment workers that support the fashion industry. It also discusses the Asia Floor Wage Proposal and its predicted effect on the global market and garment workers everywhere
Discontinuous information in the worst case and randomized settings
We believe that discontinuous linear information is never more powerful than
continuous linear information for approximating continuous operators. We prove
such a result in the worst case setting. In the randomized setting we consider
compact linear operators defined between Hilbert spaces. In this case, the use
of discontinuous linear information in the randomized setting cannot be much
more powerful than continuous linear information in the worst case setting.
These results can be applied when function evaluations are used even if
function values are defined only almost everywhere
Equations for general shells
The complete set of (field) equations for shells of arbitrary, even changing,
causal character are derived in arbitrary dimension. New equations that seem to
have never been considered in the literature emerge, even in the traditional
cases of everywhere non-null, or everywhere null, shells. In the latter case
there arise field equations for some degrees of freedom encoded exclusively in
the distributional part of the Weyl tensor. For non-null shells the standard
Israel equations are recovered but not only, the additional relations
containing also relevant information. The results are applicable to a
widespread literature on domain walls, branes and braneworlds, gravitational
layers, impulsive gravitational waves, and the like. Moreover, they are of a
geometric nature, and thus they can be used in any theory based on a Lorentzian
manifold.Comment: 32 pages, no figures. New paragraph and new footnote, plus some added
references. Version to be publishe
Is Growth an Information Technology Story in Europe Too?
While the return to growth in the US is largely credited to the rapid spreading of information technology, a key policy concern everywhere, and notably in Europe, is whether and when the US economic boom will extend abroad, and what role new technologies are about to play. In this paper, I collect and supplement data on the extent and the contribution to growth of ânew economyâ activities in Europe, and in a sample of OECD countries at large, in the 1990s. Available evidence indicates that capital accumulation in information technologies did make a contribution to growth in the EU too, though not equally everywhere. The contribution of new technologies was substantial in the UK and the Netherlands, and rapidly increasing over time in Finland, Ireland and Denmark. These were also the fast EU growing countries in the 1990s. New technologies contributed less in France, Germany, Belgium and Sweden, and marginally in Italy and Spain. Most of these countries were also âslow growersâ. I conclude that the growth gaps between the EU and the US, as well as within the EU, can (also) be associated to the diverse pace of adoption of new technologies across countries.
Hyperbolic polyhedral surfaces with regular faces
We study hyperbolic polyhedral surfaces with faces isometric to regular
hyperbolic polygons satisfying that the total angles at vertices are at least
The combinatorial information of these surfaces is shown to be
identified with that of Euclidean polyhedral surfaces with negative
combinatorial curvature everywhere. We prove that there is a gap between areas
of non-smooth hyperbolic polyhedral surfaces and the area of smooth hyperbolic
surfaces. The numerical result for the gap is obtained for hyperbolic
polyhedral surfaces, homeomorphic to the double torus, whose 1-skeletons are
cubic graphs.Comment: 23 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1804.1103
Constructing elastic distinguishability metrics for location privacy
With the increasing popularity of hand-held devices, location-based
applications and services have access to accurate and real-time location
information, raising serious privacy concerns for their users. The recently
introduced notion of geo-indistinguishability tries to address this problem by
adapting the well-known concept of differential privacy to the area of
location-based systems. Although geo-indistinguishability presents various
appealing aspects, it has the problem of treating space in a uniform way,
imposing the addition of the same amount of noise everywhere on the map. In
this paper we propose a novel elastic distinguishability metric that warps the
geometrical distance, capturing the different degrees of density of each area.
As a consequence, the obtained mechanism adapts the level of noise while
achieving the same degree of privacy everywhere. We also show how such an
elastic metric can easily incorporate the concept of a "geographic fence" that
is commonly employed to protect the highly recurrent locations of a user, such
as his home or work. We perform an extensive evaluation of our technique by
building an elastic metric for Paris' wide metropolitan area, using semantic
information from the OpenStreetMap database. We compare the resulting mechanism
against the Planar Laplace mechanism satisfying standard
geo-indistinguishability, using two real-world datasets from the Gowalla and
Brightkite location-based social networks. The results show that the elastic
mechanism adapts well to the semantics of each area, adjusting the noise as we
move outside the city center, hence offering better overall privacy
The structure of line-driven winds
Following procedures pioneered by Castor, Abbott & Klein (1975, [CAK]),
spherically-symmetric supersonic winds for O stars are computed for matching to
plane-parallel moving reversing layers (RL's) from Paper I (Lucy 2007). In
contrast to a CAK wind, each of these solutions is singularity-free, thus
allowing its mass-loss rate to be fixed by the regularity condition at the
sonic point within the RL. Moreover, information propagation in these winds by
radiative-acoustic waves is everywhere outwardly-directed, justifying the
implicit assumption in Paper I that transonic flows are unaffected by
inwardly-directed wave motions.Comment: Accepted by A&A; 7 pages, 1 table, 4 figure
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