12,274 research outputs found
The cloud paradigm: Are you tuned for the lyrics?
Major players, business angels and opinion-makers are broadcasting beguiled
lyrics on the most recent IT hype: your software should ascend to the clouds.
There are many clouds and the stake is high. Distractedly, many of us became
assiduous users of the cloud, but perhaps due to the legacy systems and legacy
knowledge, IT professionals, mainly those many that work in business
information systems for the long tail, are not as much plunged into producing
cloud-based systems for their clients.
This keynote will delve into several aspects of this cloud paradigm, from
more generic concerns regarding security and value for money, to more specific
worries that reach software engineers in general. Do we need a different
software development process? Are development techniques and tools mature
enough? What about the role of open-source in the cloud? How do we assess the
quality in cloud-based development? Please stay tuned for more!Comment: Position paper to introduce a keynote, proceedings of WAMPS'2011 - VI
Annual MPS.BR Workshop, pp. 20-25, Campinas, Brazil, October 201
The distribution of forces affects vibrational properties in hard sphere glasses
We study theoretically and numerically the elastic properties of hard sphere
glasses, and provide a real-space description of their mechanical stability. In
contrast to repulsive particles at zero-temperature, we argue that the presence
of certain pairs of particles interacting with a small force soften elastic
properties. This softening affects the exponents characterizing elasticity at
high pressure, leading to experimentally testable predictions. Denoting
the force distribution of such pairs and the
packing fraction at which pressure diverges, we predict that (i) the density of
states has a low-frequency peak at a scale , rising up to it as
, and decaying above as where and is the frequency,
(ii) shear modulus and mean-squared displacement are inversely proportional
with where
, and (iii) continuum elasticity breaks down on a
scale where
and , where is the
coordination and the spatial dimension. We numerically test (i) and provide
data supporting that in our bi-disperse system,
independently of system preparation in two and three dimensions, leading to
, , and . Our results for the
mean-square displacement are consistent with a recent exact replica computation
for , whereas some observations differ, as rationalized by the
present approach.Comment: 5 pages + 4 pages supplementary informatio
Quantum-corrected self-dual black hole entropy in tunneling formalism with GUP
In this paper we focus on the Hamilton-Jacobi method to determine the entropy
of a self-dual black hole by using linear and quadratic GUPs(generalized
uncertainty principles). We have obtained the Bekenstein-Hawking entropy of
self-dual black holes and its quantum corrections that are logarithm and also
of several other types.Comment: Latex, 7 pages, no figure. Version to appear in PLB. arXiv admin
note: substantial text overlap with arXiv:1502.0017
Freed-Witten anomaly in general flux compactification
Turning on a NS-NS three-form flux in a compact space drives some D-branes to
be either Freed-Witten anomalous or unstable to decay into fluxes by the
appearance of instantonic branes. By applying T-duality on a toroidal
compactification, the NS-flux is transformed into metric fluxes. We propose a
T-dual version of the Atiyah-Hirzebruch Spectral Sequence upon which we
describe the Freed-Witten anomaly and the brane-flux transition driven by NS
and metric fluxes in a twisted torus. The required conditions to cancel the
anomaly and the appearance of new instantonic branes are also described. In
addition, we give an example in which all D6-branes wrapping Freed-Witten
anomaly-free three-cycles in the twisted torus T^6/Z(2)XZ(2) are nevertheless
unstable to be transformed into fluxes. Evenmore we find a topological
transformation between RR, NS-NS and metric fluxes driven by a chain of
instantonic branes.Comment: v3: Shortened version. Examples added. Main results unchange
Symmetry-preserving contact interaction model for heavy-light mesons
We use a symmetry-preserving regularization method of ultraviolet divergences
in a vector-vector contact interac- tion model for low-energy QCD. The contact
interaction is a representation of nonperturbative kernels used Dyson-Schwinger
and Bethe-Salpeter equations. The regularization method is based on a
subtraction scheme that avoids standard steps in the evaluation of divergent
integrals that invariably lead to symmetry violation. Aiming at the study of
heavy-light mesons, we have implemented the method to the pseudoscalar pion and
Kaon mesons. We have solved the Dyson-Schwinger equation for the u, d and s
quark propagators, and obtained the bound-state Bethe-Salpeter amplitudes in a
way that the Ward-Green-Takahashi identities reflecting global symmetries of
the model are satisfied for arbitrary routing of the momenta running in loop
integrals
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