4,744 research outputs found
Next to subleading soft-graviton theorem in arbitrary dimensions
We study the soft graviton theorem recently proposed by Cachazo and
Strominger. We employ the Cachazo, He and Yuan formalism to show that the next
to subleading order soft factor for gravity is universal at tree level in
arbitrary dimensions.Comment: 14 pages; v2: references added, typos correcte
Conductivity in the gravity dual to massive ABJM and the membrane paradigm
In this paper we analyze the effect of the massive deformation of the ABJM
model on the calculation of conductivity of the dual theory. We show that some
of the difficulties presented by the dual geometry, in particular the
construction of black holes therein, can be at least partially circumvented by
adopting a membrane paradigm-like computation of the conductivity, which
requires us to know just the effect of the deformation on the {\it horizon} of
a black hole in AdS. The deformation at the horizon itself is found by
first deforming the flat space near the horizon, and then using the
corresponding solution near the horizon as initial conditions for the
Einstein's equations. We find the same result, showing an increase in
conductivity, using two types of membrane paradigm computations.Comment: 28 pages, explanations added, paragraph added at the end of section
The Open String Regge Trajectory and Its Field Theory Limit
We study the properties of the leading Regge trajectory in open string theory
including the open string planar one-loop corrections. With SU(N) Chan-Paton
factors, the sum over planar open string multi-loop diagrams describes the 't
Hooft limit N\to\infty. Our motivation is to improve the understanding of open
string theory at finite \alpha' as a model of gauge theories. SU(N) gauge
theories in D space-time dimensions are described by requiring open strings to
end on a stack of N Dp-branes of space-time dimension D=p+1. The large N
leading trajectory \alpha(t)=1+\alpha' t+\Sigma(t) can be extracted, through
order g^2, from the s\to-\infty limit, at fixed t, of the four open string tree
and planar loop diagrams. We analyze the t\to0 behavior with the result that
\Sigma(t)\sim-Cg^2(-\alpha' t)^{(D-4)/2}/(D-4). This result precisely tracks
the 1-loop Reggeized gluon of gauge theory in D>4 space-time dimensions. In
particular, for D\to4 it reproduces the known infrared divergences of gauge
theory in 4 dimensions with a Regge trajectory behaving as -\ln(-\alpha^\prime
t). We also study \Sigma(t) in the limit t\to-\infty and show that, when D<8,
it behaves as \alpha^\prime t/(\ln(-\alpha^\prime t))^{\gamma}, where \gamma>0
depends on D and the number of massless scalars. Thus, as long as 4<D<8, the
1-loop correction stays small relative to the tree trajectory for the whole
range -\infty<t<0. Finally we present the results of numerical calculations of
\Sigma(t) for all negative t.Comment: 19 pages, 5 figure
Grasping bulky objects with two anthropomorphic hands
© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper presents an algorithm to compute precision grasps for bulky objects using two anthropomorphic hands. We use objects modeled as point clouds obtained from a sensor camera or from a CAD model. We then process the point clouds dividing them into two set of slices where we look for sets of triplets of points. Each triplet must accomplish some physical conditions based on the structure of the hands. Then, the triplets of points from each set of slices are evaluated to find a combination that satisfies the force closure condition (FC). Once one valid couple of triplets have been found the inverse kinematics of the system is computed in order to know if the corresponding points are reachable by the hands, if so, motion planning and a collision check are performed to asses if the final grasp configuration of the system is suitable. The paper
inclu des some application examples of the proposed approachAccepted versio
The spread of Marxism during the franco regime: Artiach Editorial case (1969-1974)
Este artículo es inédito y complementario al estudio Dirigismo cultural y disidencia editorial en España (1962-1973), Alicante, Publicaciones de la Universidad de Alicante, 2013, versión corregida y ampliada de mi tesis doctoralArtiach Editorial (1969-1974) fue una editorial marxista creada dentro de un proyecto cultural antifranquista mucho más amplio, relacionado con el PCE. En este artículo se estudia partiuclarmente su origen, su producción bibliográfica y su dialéctica con los mecanismos de control ideológico de la dictaduraArtiach Editorial (1969-1974) was a Marxist publishing house created within a broader anti-Francoism cultural project, link to the Comunist
Party of Spain (Partido Comunista Español). In this paper we will study its origin, its bibliographic production and its dialectics, along with the mechanisms of ideological control of the dictatorshi
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