27 research outputs found
Основания применения мер дисциплинарного принуждения к профессиональным участникам рынка ценных бумаг Комиссией по ценным бумагам и биржам США
The article focuses on the analysis of the legal grounds for enforcement of disciplinary sanctions to security professionals in the U.S. For this purpose it is considered an appropriate legal acts which are the basis of an administrative legal mechanism of enforcement of disciplinary sanctions to security professionals and it is explored the SEC administrative practice in this area.В статье дается анализ правовых оснований применения мер дисциплинарной ответственности к профессиональным участникам рынка ценных бумаг в США. С этой целью рассмотрены соответствующие нормативно-правовые акты, на основе которых сложился административно-правовой механизм применения к участникам рынка ценных бумаг мер дисциплинарного воздействия, и исследуется административная практика Комиссии по ценным бумагам и биржам США в этой области
Linear Sigma Models of H and KK Monopoles
We propose a gauged linear sigma model of k H-monopoles. We also consider the
T-dual of this model describing KK-monopoles and clarify the meaning of
"winding coordinate" studied recently in hep-th/0507204.Comment: 13 pages, lanlmac; V3:added argument on the nature of disk instanto
Hyperkahler Metrics from Periodic Monopoles
Relative moduli spaces of periodic monopoles provide novel examples of
Asymptotically Locally Flat hyperkahler manifolds. By considering the
interactions between well-separated periodic monopoles, we infer the asymptotic
behavior of their metrics. When the monopole moduli space is four-dimensional,
this construction yields interesting examples of metrics with self-dual
curvature (gravitational instantons). We discuss their topology and complex
geometry. An alternative construction of these gravitational instantons using
moduli spaces of Hitchin equations is also described.Comment: 23 pages, latex. v2: an erroneous formula is corrected, and its
derivation is given. v3 (published version): references adde
Changes in the structure of MgxAly(OH)z layered double hydroxides during the adsorption of organic compounds
International audienceLayered double hydroxides (LDHs) are used as sorbents, catalysts, and carriers for catalytic species. In general, they are natural or synthetic minerals with part of their cations being replaced isomorphically with cations of higher oxidation states, which results in the formation of positively charged two-dimensional layers containing solvate molecules and counterions capable of anion exchange [1]. LDHs are solid bases [2]. Since there are both Brønsted and Lewis sites, anion exchange processes occur in the interlayer internal space of LDHs [3]. The interlayer distance depends on the nature of anions and solvate molecules as well as the degree of isomorphic substitution. When the interlayer distance changes, LDH properties also change (for example, sorption capacity changes because of the changing number of available active sites). A study of the LDH structure and its changes during the sorption of various compounds provides conclusions about the mechanism of these processes and prospects of creating new materials with desired properties. This work reveals regular changes in the structure of synthetic MgxAly(OH)z hydrotalcites of various composition, which occur during the adsorption of amyl alcohol, naphthalene, and β-naphthol. The hydrotalcite structure is shown in Fig. 1
Supergravity Solution of Intersecting Branes and AdS/CFT with Flavor
We construct the supergravity solution for fully localized D2/D6
intersection. The near horizon limit of this solution is the supergravity dual
of supersymmetric Yang-Mills theory in 2+1 dimensions with flavor. We use this
solution to formulate mirror symmetry of 2+1 dimensional gauge theories in the
language of AdS/CFT correspondence. We also construct the supergravity dual of
a non-commutative gauge theory with fundamental matter.Comment: 17 Pages, 2 figures, references added. Minor corrections to eqs (5.3)
and (5.4
Radar probing of surfactant films on the water surface using dual co-polarized SAR
Microwave radar is a very perspective tool for all-weather monitoring of film slicks which appear in radar imagery of the water surface as areas of reduced backscattering due to damping of short wind waves. Information about the backscatter variations obtained from single band/one polarization radar seems to be insufficient for film characterization, so, new capabilities of multi-polarization radar for monitoring of film slicks have been actively discussed in the literature. In this paper results of new field experiments on remote sensing of film slicks using dual co-polarized radars: a satellite X-band TerraSAR-X and recently designed at IAP RAS a Multifrequency Radar Complex - three-band scatterometer operating in X-/C-/S-bands and mounted onboard a ship are presented. Along with backscattering depression the variations of polarized (Bragg) and non polarized radar backscatter components in slicks were analyzed. It is obtained that VV-to-HH backscatter ratio is smaller than the ratio predicted by a Bragg (two-scale) model thus indicating that additional, non polarized (NP), component also contributes to the total radar backscatter. Assuming the radar backscatter to be a sum of polarized (Bragg) and NP components the latter was eliminated from the total radar backscatter, and contrasts for the Bragg and NP components were obtained. The contrasts for the polarized component allowed us to estimate damping of gravity-capillary wind waves at Bragg wavelengths in slick and to give more accurate comparison with models of wave damping due to elastic film
Moduli Spaces of Instantons on the Taub-NUT Space
We present ADHM-Nahm data for instantons on the Taub-NUT space and encode
these data in terms of Bow Diagrams. We study the moduli spaces of the
instantons and present these spaces as finite hyperkahler quotients. As an
example, we find an explicit expression for the metric on the moduli space of
one SU(2) instanton. We motivate our construction by identifying a
corresponding string theory brane configuration. By following string theory
dualities we are led to supersymmetric gauge theories with impurities.Comment: 26 pages, 7 figure
Mesons in gauge/gravity dual with large number of fundamental fields
In view of extending gauge/gravity dualities with flavour beyond the probe
approximation, we establish the gravity dual description of mesons for a
three-dimensional super Yang-Mills theory with fundamental matter. For this
purpose we consider the fully backreacted D2/D6 brane solution of Cherkis and
Hashimoto in an approximation due to Pelc and Siebelink. The low-energy field
theory is the IR fixed point theory of three-dimensional N=4 SU(N_c) super
Yang-Mills with N_f fundamental fields, which we consider in a large N_c and
N_f limit with N_f/N_c finite and fixed. We discuss the dictionary between
meson-like operators and supergravity fluctuations in the corresponding
near-horizon geometry. In particular, we find that the mesons are dual to the
low-energy limit of closed string states. In analogy to computations of
glueball mass spectra, we calculate the mass of the lowest-lying meson and find
that it depends linearly on the quark mass.Comment: 19 pages, LaTeX, 6 figures, v2: fig. 4 added, refs. adde
On gravitational description of Wilson lines
We study solutions of Type IIB supergravity, which describe the geometries
dual to supersymmetric Wilson lines in N=4 super-Yang-Mills. We show that the
solutions are uniquely specified by one function which satisfies a Laplace
equation in two dimensions. We show that if this function obeys a certain
Dirichlet boundary condition, the corresponding geometry is regular, and we
find a simple interpretation of this boundary condition in terms of D3 and D5
branes which are dissolved in the geometry. While all our metrics have AdS_5 x
S^5 asymptotics, they generically have nontrivial topologies, which can be
uniquely specified by a set of non-contractible three- and five-spheres.Comment: 46 page
Supersymmetric Wilson loops on S^3
This paper studies in great detail a family of supersymmetric Wilson loop
operators in N=4 supersymmetric Yang-Mills theory we have recently found. For a
generic curve on an S^3 in space-time the loops preserve two supercharges but
we will also study special cases which preserve 4, 8 and 16 supercharges. For
certain loops we find the string theory dual explicitly and for the general
case we show that string solutions satisfy a first order differential equation.
This equation expresses the fact that the strings are pseudo-holomorphic with
respect to a novel almost complex structure we construct on AdS_4 x S^2. We
then discuss loops restricted to S^2 and provide evidence that they can be
calculated in terms of similar observables in purely bosonic YM in two
dimensions on the sphere.Comment: Latex, 84 pages, 4 figures. v2: minor changes, references added; to
appear in JHE