228 research outputs found
Chern-Simons action for inhomogeneous Virasoro group as an extension of three dimensional flat gravity
We initiate the study of a Chern-Simons action associated to the semi-direct
sum of the Virasoro algebra with its coadjoint representation. This model
extends the standard Chern-Simons formulation of three dimensional flat gravity
and is similar to the higher-spin extension of three dimensional anti-de Sitter
or flat gravity. The extension can also be constructed for the exotic but not
for the cosmological constant deformation of flat gravity.Comment: 15 pages. Version to appear in J. of Math. Phy
Complete Calabi-Yau metrics from Kahler metrics in D=4
In the present work the local form of certain Calabi-Yau metrics possessing a
local Hamiltonian Killing vector is described in terms of a single non linear
equation. The main assumptions are that the complex -form is of the form
, where is preserved by the Killing
vector, and that the space of the orbits of the Killing vector is, for fixed
value of the momentum map coordinate, a complex 4-manifold, in such a way that
the complex structure of the 4-manifold is part of the complex structure of the
complex 3-fold. The link with the solution generating techniques of [26]-[28]
is made explicit and in particular an example with holonomy exactly SU(3) is
found by use of the linearization of [26], which was found in the context of D6
branes wrapping a holomorphic 1-fold in a hyperkahler manifold. But the main
improvement of the present method, unlike the ones presented in [26]-[28], does
not rely in an initial hyperkahler structure. Additionally the complications
when dealing with non linear operators over the curved hyperkahler space are
avoided by use of this method.Comment: Version accepted for publication in Phys.Rev.
Octopus maya white body show sex-specific transcriptomic profiles during the reproductive phase, with high differentiation in signaling pathways
White bodies (WB), multilobulated soft tissue that wraps the optic tracts and optic lobes, have been considered the hematopoietic organ of the cephalopods. Its glandular appearance and its lobular morphology suggest that different parts of the WB may perform different functions, but a detailed functional analysis of the octopus WB is lacking. The aim of this study is to describe the transcriptomic profile of WB to better understand its functions, with emphasis on the difference between sexes during reproductive events. Then, validation via qPCR was performed using different tissues to find out tissue-specific transcripts. High differentiation in signaling pathways was observed in the comparison of female and male transcriptomic profiles. For instance, the expression of genes involved in the androgen receptor-signaling pathway were detected only in males, whereas estrogen receptor showed higher expression in females. Highly expressed genes in males enriched oxidation-reduction and apoptotic processes, which are related to the immune response. On the other hand, expression of genes involved in replicative senescence and the response to cortisol were only detected in females. Moreover, the transcripts with higher expression in females enriched a wide variety of signaling pathways mediated by molecules like neuropeptides, integrins, MAPKs and receptors like TNF and Toll-like. In addition, these putative neuropeptide transcripts, showed higher expression in females' WB and were not detected in other analyzed tissues. These results suggest that the differentiation in signaling pathways in white bodies of O. maya influences the physiological dimorphism between females and males during the reproductive phase
Information vs Engagement in parliamentary websites – a case study of Brazil and the UK
Parliamentary websites have become the main window of parliament to the outside world. More than a gimmick, they are an essential element in the promotion of a relationship between parliament and citizens. This paper develops a comparative analysis of the websites of the lower chambers of the Brazilian and the British parliaments, respectively the Chamber of Deputies and the House of Commons. We structure this analysis around three dimensions: 1) information about the institution; 2) information about parliamentary activity; and 3) tools to promote engagement with the public. The choice of two very different case studies enables us to consider more clearly the specific purposes of these parliamentary websites. We consider in particular if these parliaments' institutional differences affect their websites. The websites' analysis is complemented by semi-structured elite interviews with parliamentary staff who manage the services provided by these websites. Our analysis shows that both websites achieve much higher levels of complexity in the information area than in engagement. But it also shows that the Brazilian parliament website includes far more tools designed for public interaction than its UK counterpart. The indexes and interviews show that both institutions are highly committed to disseminating data and information to citizens. This is seen as a path towards achieving higher accountability and improving knowledge about parliamentary processes and, consequently, improving public image and levels of trust. Whilst there is a strong focus on the provision of information, there is still little evidence of enabling citizen participation in the legislative process. This is partly due to a tension between conceptions of representative democracy and those of participatory democracy. The articulation between these different types of democracy still has a long way to be resolved, although parliaments are slowly introducing participatory tools
Geometric Configurations, Regular Subalgebras of E10 and M-Theory Cosmology
We re-examine previously found cosmological solutions to eleven-dimensional
supergravity in the light of the E_{10}-approach to M-theory. We focus on the
solutions with non zero electric field determined by geometric configurations
(n_m, g_3), n\leq 10. We show that these solutions are associated with rank
regular subalgebras of E_{10}, the Dynkin diagrams of which are the (line)
incidence diagrams of the geometric configurations. Our analysis provides as a
byproduct an interesting class of rank-10 Coxeter subgroups of the Weyl group
of E_{10}.Comment: 48 pages, 27 figures, 5 tables, references added, typos correcte
On higher derivative gravity, c-theorems and cosmology
We consider higher derivative gravity lagrangians in 3 and 4 dimensions,
which admit simple c-theorems, including upto six derivative curvature
invariants. Following a suggestion by Myers, these lagrangians are restricted
such that the fluctuations around (anti) de Sitter spaces have second order
linearized equations of motion. We study c-theorems both in the context of
AdS/CFT and cosmology. In the context of cosmology, the monotonic function is
the entropy defined on the apparent horizon through Wald's formula. Exact black
hole solutions which are asymptotically (anti) de Sitter are presented. An
interesting lower bound for entropy is found in de Sitter space. Some aspects
of cosmology in both D=3 and D=4 are discussed.Comment: 23 pages, v3: clarifications added, references adde
Thermal Correlators in Holographic Models with Lifshitz scaling
We study finite temperature effects in two distinct holographic models that
exhibit Lifshitz scaling, looking to identify model independent features in the
dual strong coupling physics. We consider the thermodynamics of black branes
and find different low-temperature behavior of the specific heat. Deformation
away from criticality leads to non-trivial temperature dependence of
correlation functions and we study how the characteristic length scale in the
two point function of scalar operators varies as a function of temperature and
deformation parameters.Comment: 28 pages, 8 figures; typos corrected, references added, published
versio
Study on the criteria for assessing skull-face correspondence in craniofacial superimposition
Craniofacial superimposition has the potential to be used as an identification method when other traditional biological techniques are not applicable due to insufficient quality or absence of ante-mortem and post-mortem data. Despite having been used in many countries as a method of inclusion and exclusion for over a century it lacks standards. Thus, the purpose of this research is to provide forensic practitioners with standard criteria for analysing skull-face relationships. Thirty-seven experts from 16 different institutions participated in this study, which consisted of evaluating 65 criteria for assessing skull-face anatomical consistency on a sample of 24 different skull-face superimpositions. An unbiased statistical analysis established the most objective and discriminative criteria. Results did not show strong associations, however, important insights to address lack of standards were provided. In addition, a novel methodology for understanding and standardizing identification methods based on the observation of morphological patterns has been proposed
Disability, anxiety and depression associated with medication-overuse headache can be considerably reduced by detoxification and prophylactic treatment. Results from a multicentre, multinational study (COMOESTAS project)
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Type IIB orientifolds on Gepner points
We study various aspects of orientifold projections of Type IIB closed string
theory on Gepner points in different dimensions. The open string sector is
introduced, in the usual constructive way, in order to cancel RR charges
carried by orientifold planes. Moddings by cyclic permutations of the internal
N=2 superconformal blocks as well as by discrete phase symmetries are
implemented. Reduction in the number of generations, breaking or enhancements
of gauge symmetries and topology changes are shown to be induced by such
moddings. Antibranes sector is also considered; in particular we show how non
supersymmetric models with antibranes and free of closed and open tachyons do
appear in this context. A systematic study of consistent models in D=8
dimensions and some illustrative examples in D=6 and D=4 dimensions are
presented.Comment: 67 pages, no figures References added, typos correcte
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