1,720,952 research outputs found
Author Correction: Discovery of a radiation component from the Vela pulsar reaching 20 teraelectronvolts
No full textIn the version of the article initially published, R. Zanin, M. Kerr, S. Johnston, R. M. Shannon and D. A. Smith mistakenly appeared in the main author list but are now instead listed as members of The H.E.S.S. Collaboration et al. in the HTML and PDF versions of the article
Marine diterpene glycosides
No full textMarine diterpene glycosides (MDGs) respresent a small but highly significant group of the much larger class of marine diterpenes. The three well-studied examples of MDGs are eleutherobins, pseudopterosins and fuscosides, all of which exhibit extremely promising biological activity. The eleutherobins are potent anti-mitotic agents, and the pseudopterosins and fuscosides are potent anti-inflammatory agents. This review discusses the structures and biological activities of these compounds, as well as their biosynthesis and synthesis
Real-time correlators and hidden conformal symmetry in the Kerr/CFT correspondence
No full textIn this paper, we study the real-time correlators in Kerr/CFT, in the low frequency limit of generic non-extremal Kerr(-Newman) black holes. From the low frequency scattering off Kerr-Newman black holes, we show that for the uncharged scalar scattering, there exists hidden conformal symmetry on the solution space. Similar to Kerr case, this suggests that the Kerr-Newman black hole is dual to a two-dimensional CFT with central charges c(L) = c(R) = 12J and temperatures T-L = (r(+)+ r(-))-Q(2)/M/4 pi a, T-R = r(+)-r(-)/4 pi a. Using the Minkowski prescription, we compute the real-time correlators of a charged scalar and find perfect match with CFT prediction. We further discuss the low-frequency scattering of photons and gravitons by a Kerr black hole and find that their retarded Green's functions are in good agreement with CFT prediction. Our study shows that hidden conformal symmetry in the solution space is essential to set up and check the Kerr/CFT correspondence.Physics, Particles & FieldsSCI(E)28ARTICLE6nul
On holographic description of the Kerr-Newman-AdS-dS black holes
No full textIn this paper, we study the holographic description of the generic four-dimensional non-extremal Kerr-Newman-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, there exists hidden conformal symmetry on the solution space. Similar to the Kerr case, this suggests that the Kerr-Newman-AdS-dS black hole is dual to a two-dimensional CFT with central charges c(L) = c(R) = 6a(r+ +r*)/k and temperatures T-L = k(r(+)(2)+ r(*)(2) + 2a(2))/4 pi a Xi(r +1r(*)), T-R = k(r(+)- r(*))/4 pi Xi. The macroscopic Bekenstein-Hawking entropy could be recovered from the microscopic counting in dual CFT via the Cardy formula. Using the Minkowski prescription, we compute the real- time correlators of the scalar, photon and graviton in near horizon geometry of near extremal Kerr-AdS-dS black hole. In all these cases, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction. We further discuss the low- frequency scattering of a charged scalar by a Kerr-Newman-AdS-dS black hole and find the dual CFT description.Physics, Particles & FieldsSCI(E)22ARTICLE8nul
Polynomial rings over Goldie-Kerr commutative rings
No full textAll rings in this paper are commutative, and
acc
⊥
\operatorname {acc} \bot
(resp.,
acc
⊕
\operatorname {acc} \, \oplus
) denotes the acc on annihilators (resp., on direct sums of ideals). Any subring of an
acc
⊥
\operatorname {acc} \bot
ring, e.g., of a Noetherian ring, is an
acc
⊥
\operatorname {acc} \bot
ring. Together,
acc
⊥
\operatorname {acc} \bot
and
acc
⊕
\operatorname {acc} \, \oplus
constitute the requirement for a ring to be a Goldie ring. Moreover, a ring
R
R
is Goldie iff its classical quotient ring
Q
Q
is Goldie. A ring
R
R
is a Kerr ring (the appellation is for J. Kerr, who in 1990 constructed the first Goldie rings not Kerr) iff the polynomial ring
R
[
x
]
R[x]
has
acc
⊥
\operatorname {acc} \bot
(in which case
R
R
must have
acc
⊥
\operatorname {acc} \bot
). By the Hilbert Basis theorem, if
S
S
is a Noetherian ring, then so is
S
[
x
]
S[x]
; hence, any subring
R
R
of a Noetherian ring is Kerr. In this note, using results of Levitzki, Herstein, Small, and the author, we show that any Goldie ring
R
R
such that
Q
=
Q
c
(
R
)
Q = {Q_c}(R)
has nil Jacobson radical (equivalently, the nil radical of
R
R
is an intersection of associated prime ideals) is Kerr in a very strong sense:
Q
Q
is Artinian and, hence, Noetherian (Theorems 1.1 and 2.2). As a corollary we prove that any Goldie ring
A
A
that is algebraic over a field
k
k
is Artinian, and, hence, any order
R
R
in
A
A
is a Kerr ring (Theorem 2.5 and Corollary 2.6). The same is true of any algebra
A
A
over a field
k
k
of cardinality exceeding the dimension of
A
A
(Corollary 2.7). Other Kerr rings are: reduced
acc
⊥
\operatorname {acc} \bot
rings and valuation rings with
acc
⊥
\operatorname {acc} \bot
(see 3.3 and 3.4).</p
Selective sensitivity in Kerr microscopy
Get PDFA new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time, and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for Permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6 mdeg is demonstrated. © 2017 Author(s)
International Harmonization and the Gains from Trade
Get PDFInternational harmonization of standards and regulations is often a goal expressed in trade agreements because it is expected to yield gains from trade. Absence of progress toward harmonization is often interpreted as being motivated by protectionism, with differences in standards and regulations seen as non-tariff barriers. While protectionism may well be the source of resistance to harmonization, there may be other reasons it is not pursued. These alternative explanations have not received much attention from economists. In this article some of these alternatives are outlined - demand effects from altering standards, switching costs, proprietary technologies. The article concludes that proposals for international harmonization need to be scrutinized carefully.demand effects, harmonization, regulation, standards, switching costs, TBT, International Relations/Trade,
Chemotaxonomic relationships within, and comparisons between, the orders haplosclerida and petrosida (porifera, demospongiae) using sterol complements
No full textRecession, International Trade and the Fallacies of Composition
Get PDFA truly global recession has not been manifest since the Great Depression of the 1930s. As a result, the multilateral institutions put in place at the end of the Second World War to ensure that a major depression never happened again have not been tested. One of the lessons of the Great Depression was that governments had a major role to play in managing the economy. The use of subsidies to affect economic outcomes was one manifestation of this expanded role. In a recession, sector specific subsidies will likely be requested by firms. Subsidies can distort trade, leading to the potential for beggar thy neighbour subsidy wars. Subsidies will be difficult to discipline in a global recession.beggar thy neighbour, deficits, paradox of thrift, recession, subsidies, International Relations/Trade,
Holographic description of Kerr-Bolt-AdS-dS spacetimes
No full textWe show that there exists a holographic 2D CFT description of a Kerr-Bolt-AdS-dS spacetime. We first consider the wave equation of a massless scalar field propagating in extremal Kerr-Bolt-AdS-dS spacetimes and find in the "near region", the wave equation in extremal limit could be written in terms of the SL(2, R) quadratic Casimir. This suggests that there exist dual CFT descriptions of these black holes. In the probe limit, we compute the scattering amplitudes of the scalar off the extremal black holes and find perfect agreement with the CFT prediction. Furthermore we study the holographic description of the generic four-dimensional non-extremal Kerr-Bolt-AdS-dS black holes. We find that if focusing on the near-horizon region, for the massless scalar scattering in the low-frequency limit, the radial equation could still be rewritten as the SL(2, R) quadratic Casimir, suggesting the existence of dual 2D description. We read the temperatures of the dual CFT from the conformal coordinates and obtain the central charges by studying the near-horizon geometry of near-extremal black holes. We recover the macroscopic entropy from the microscopic counting. We also show that for the super-radiant scattering, the retarded Green's functions and the corresponding absorption cross sections are in perfect match with CFT prediction. (C) 2011 Elsevier B.V. All rights reserved.Physics, Particles & FieldsSCI(E)11ARTICLE1108-12084
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