1,359 research outputs found
An integrated dynamical modeling perspective for infrastructure resilience
International audienceThis paper considers a dynamical way to connect resilience outcomes and processes by nesting process-based approaches inside a controlled dynamical system under resource constraints. To illustrate this, we use a dynamical model of electric power generation to show the complementary aspects of outcome, resources, and process-based approaches for analyzing infrastructure resilience. The results of this stylized model show that adaptation is the most influential process and that for monitoring to be efficient it must account for associated costs. Beyond these specific results, we suggest that nesting outcome- and process-based approaches within a dynamical controlled framework can be very useful and complementary for infrastructure managers and designers tasked with effectively allocating resources for enhancing system resilience
Liquid Crystal-Solid Interface Structure at the Antiferroelectric-Ferroelectric Phase Transition
Total Internal Reflection (TIR) is used to probe the molecular organization
at the surface of a tilted chiral smectic liquid crystal at temperatures in the
vicinity of the bulk antiferroelectric-ferroelectric phase transition. Data are
interpreted using an exact analytical solution of a real model for
ferroelectric order at the surface. In the mixture T3, ferroelectric surface
order is expelled with the bulk ferroelectric-antiferroelectric transition. The
conditions for ferroelectric order at the surface of an antiferroelectric bulk
are presented
Janus within Janus
We found a simple and interesting generalization of the non-supersymmetric
Janus solution in type IIB string theory. The Janus solution can be thought of
as a thick AdS_d-sliced domain wall in AdS_{d+1} space. It turns out that the
AdS_d-sliced domain wall can support its own AdS_{d-1}-sliced domain wall
within it. Indeed this pattern persists further until it reaches the
AdS_2-slice of the domain wall within self-similar AdS_{p (2<p\le d)}-sliced
domain walls. In other words the solution represents a sequence of little Janus
nested in the interface of the parent Janus according to a remarkably simple
``nesting'' rule. Via the AdS/CFT duality, the dual gauge theory description is
in general an interface CFT of higher codimensions.Comment: 15 pages, 6 figures, v2 references added. v3 eq.(3.33) correcte
Young star clusters in M31
In our study of M31's globular cluster system with MMT/Hectospec, we have
obtained high-quality spectra of 85 clusters with ages less than 1 Gyr. With
the exception of Hubble V, the young cluster in NGC 205, we find that these
young clusters have kinematics and spatial distribution consistent with
membership in M31's young disk. Preliminary estimates of the cluster masses and
structural parameters, using spectroscopically derived ages and HST imaging,
confirms earlier suggestions that M31 has clusters similar to the LMC's young
populous clusters.Comment: 4 pages, 1 figure, contributed talk at "Galaxies in the Local Volume"
conference in Sydney, July 200
Geodesics and Geodesic Deviation in static Charged Black Holes
The radial motion along null geodesics in static charged black hole
space-times, in particular, the Reissner-Nordstr\"om and stringy charged black
holes are studied. We analyzed the properties of the effective potential. The
circular photon orbits in these space-times are investigated. We found that the
radius of circular photon orbits in both charged black holes are different and
differ from that given in Schwarzschild space-time. We studied the physical
effects of the gravitational field between two test particles in stringy
charged black hole and compared the results with that given in Schwarzschild
and Reissner-Nordstr\"om black holes.Comment: 12 pages, 5 figures, small changes, figures and references added,
conclusions changed. A improved, version accepted in Astrophysics and Space
Scienc
Jastrow-type calculations of one-nucleon removal reactions on open - shell nuclei
Single-particle overlap functions and spectroscopic factors are calculated on
the basis of Jastrow-type one-body density matrices of open-shell nuclei
constructed by using a factor cluster expansion. The calculations use the
relationship between the overlap functions corresponding to bound states of the
-particle system and the one-body density matrix for the ground state of
the -particle system. In this work we extend our previous analyses of
reactions on closed-shell nuclei by using the resulting overlap functions for
the description of the cross sections of reactions on the open -
shell nuclei Mg, Si and S and of S
reaction. The relative role of both shell structure and short-range
correlations incorporated in the correlation approach on the spectroscopic
factors and the reaction cross sections is pointed out.Comment: 11 pages, 5 figures, to be published in Phys. Rev.
AdS Branes Corresponding to Superconformal Defects
We investigate an AdS_4 x L_2 D5-brane in AdS_5 x X_5 space-time, in the
context of AdS/dCFT correspondence. Here, X_5 is a Sasaki-Einstein manifold and
L_2 is a submanifold of X_5. This brane has the same supersymmetry as the
3-dimensional N=1 superconformal symmetry if L_2 is a special Legendrian
submanifold in X_5. In this case, this brane is supposed to correspond to a
superconformal wall defect in 4-dimensional N=4 super Yang-Mills theory. We
construct these new string backgrounds and show they have the correct
supersymmetry, also in the case with non-trivial gauge flux on L_2. The
simplest new example is AdS_4 x T^2 brane in AdS_5 x S^5. We construct the
brane solution expressing the RG flow between two different defects. We also
perform similar analysis for an AdS_3 x L_3 M5-brane in AdS_4 x X_7, for a weak
G_2 manifold X_7 and its submanifold L_3. This system has the same
supersymmetry as 2-dimensional N=(1,0) global superconformal symmetry, if L_3
is an associative submanifold.Comment: 22 pages, LaTeX, 3 figures. v2: typos corrected, references added.
v3: typos correcte
Null Deformed Domain Wall
We study null 1/4 BPS deformations of flat domain wall solutions (NDDW) in
N=2, d=5 gauged supergravity with hypermultiplets and vector multiplets
coupled. These are uncharged time-dependent configurations and contain as
special case, 1/2 supersymmetric flat domain walls (DW), as well as 1/2 BPS
null solutions of the ungauged supergravity. Combining our analysis with the
classification method initiated by Gauntlett et al., we prove that all the
possible deformations of the DW have origin in the hypermultiplet sector or/and
are null. Here, we classify all the null deformations: we show that they
naturally organize themselves into "gauging" (v-deformation) and "non gauging"
(u-deformation). They have different properties: only in presence of
v-deformation is the solution supported by a time-dependent scalar potential.
Furthermore we show that the number of possible deformations equals the number
of matter multiplets coupled. We discuss the general procedure for constructing
explicit solutions, stressing the crucial role taken by the integrability
conditions of the scalars as spacetime functions. Two analytical solutions are
presented. Finally, we comment on the holographic applications of the NDDW, in
relation to the recently proposed time-dependent AdS/CFT.Comment: 38 pages; minor changes, references added; text revised, minor
changes, final version published in JHE
Relic neutrino masses and the highest energy cosmic rays
We consider the possibility that a large fraction of the ultrahigh energy
cosmic rays are decay products of Z bosons which were produced in the
scattering of ultrahigh energy cosmic neutrinos on cosmological relic
neutrinos. We compare the observed ultrahigh energy cosmic ray spectrum with
the one predicted in the above Z-burst scenario and determine the required mass
of the heaviest relic neutrino as well as the necessary ultrahigh energy cosmic
neutrino flux via a maximum likelihood analysis. We show that the value of the
neutrino mass obtained in this way is fairly robust against variations in
presently unknown quantities, like the amount of neutrino clustering, the
universal radio background, and the extragalactic magnetic field, within their
anticipated uncertainties. Much stronger systematics arises from different
possible assumptions about the diffuse background of ordinary cosmic rays from
unresolved astrophysical sources. In the most plausible case that these
ordinary cosmic rays are protons of extragalactic origin, one is lead to a
required neutrino mass in the range 0.08 eV - 1.3 eV at the 68 % confidence
level. This range narrows down considerably if a particular universal radio
background is assumed, e.g. to 0.08 eV - 0.40 eV for a large one. The required
flux of ultrahigh energy cosmic neutrinos near the resonant energy should be
detected in the near future by AMANDA, RICE, and the Pierre Auger Observatory,
otherwise the Z-burst scenario will be ruled out.Comment: 19 pages, 22 figures, REVTeX
On the covariant quantization of tensionless bosonic strings in AdS spacetime
The covariant quantization of the tensionless free bosonic (open and closed)
strings in AdS spaces is obtained. This is done by representing the AdS space
as an hyperboloid in a flat auxiliary space and by studying the resulting
string constrained hamiltonian system in the tensionless limit. It turns out
that the constraint algebra simplifies in the tensionless case in such a way
that the closed BRST quantization can be formulated and the theory admits then
an explicit covariant quantization scheme. This holds for any value of the
dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde
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