New string vacua from twistor spaces

We find a new family of AdS_4 vacua in IIA string theory. The internal space is topologically either the complex projective space CP^3 or the "flag manifold" SU(3)/(U(1)xU(1)), but the metric is in general neither Einstein nor Kaehler. All known moduli are stabilized by fluxes, without using quantum effects or orientifold planes. The analysis is completely ten--dimensional and does not rely on assumptions about Kaluza--Klein reduction.Comment: 19 pages. v3: published version, further minor correction

Solidifying system of democracy in the Central and Eastern European new EU members

The paper examines the requirements of an effective and legitimized democratic political system in the process of transition. The analysis and the conclusions are based on the Hungarian experience, which can carefully be applied to all Central and Eastern European (CEE) countries. Special focus is given to the relationship of legal certainty and the efficiency of the democratic system, to the tension between legalism and managerialism and to the characteristics of civil society organizations. In the conclusion special features of the transitional countries are pointed out

The Tetramethylpiperidinyl-1-Oxide Anion (TMPO-) as a Ligand in Lanthanide Chemistry: Synthesis of the Per(TMPO-) Complex [(ONC5H6Me4)2Sm(μ-ONC5H6Me4)]2

(C5Me5)3Sm reacts with the free radical 2,2,6,6-tetramethylpiperidinyl-1-oxy (TMPO) to form (C5Me5)2 and the per nitroxide [(η1-ONC5H6Me4)2 Sm(μ-η1∶η2-ONC5H 6Me4)]

Nonnegatively curved homogeneous metrics obtained by scaling fibers of submersions

We consider invariant Riemannian metrics on compact homogeneous spaces G/H where an intermediate subgroup K between G and H exists, so that the homogeneous space G/H is the total space of a Riemannian submersion. We study the question as to whether enlarging the fibers of the submersion by a constant scaling factor retains the nonnegative curvature in the case that the deformation starts at a normal homogeneous metric. We classify triples of groups (H,K,G) where nonnegative curvature is maintained for small deformations, using a criterion proved by Schwachh\"ofer and Tapp. We obtain a complete classification in case the subgroup H has full rank and an almost complete classification in the case of regular subgroups.Comment: 23 pages; minor revisions, to appear in Geometriae Dedicat

On the terms violating the custodial symmetry in multi-Higgs-doublet models

We prove that a generic multi-Higgs-doublet model (NHDM) generally must contain terms in the potential that violate the custodial symmetry. This is done by showing that the O(4) violating terms of the NHDM potential cannot be excluded by imposing a symmetry on the NHDM Lagrangian. Hence we expect higher-order corrections to necessarily introduce such terms. We also note, in the case of custodially symmetric Higgs-quark couplings, that vacuum alignment will lead to up-down mass degeneration; this is not true if the vacua are not aligned.Comment: 16 pages, 1 figure. Title and abstract are modified, conclusions remain the same. Section on Yukawa couplings is extended. Published versio

Temporally divergent regulatory mechanisms govern neuronal diversification and maturation in the mouse and marmoset neocortex

Mammalian neocortical neurons span one of the most diverse cell type spectra of any tissue. Cortical neurons are born during embryonic development, and their maturation extends into postnatal life. The regulatory strategies underlying progressive neuronal development and maturation remain unclear. Here we present an integrated single-cell epigenomic and transcriptional analysis of individual mouse and marmoset cortical neuron classes, spanning both early postmitotic stages of identity acquisition and later stages of neuronal plasticity and circuit integration. We found that, in both species, the regulatory strategies controlling early and late stages of pan-neuronal development diverge. Early postmitotic neurons use more widely shared and evolutionarily conserved molecular regulatory programs. In contrast, programs active during later neuronal maturation are more brain- and neuron-specific and more evolutionarily divergent. Our work uncovers a temporal shift in regulatory choices during neuronal diversification and maturation in both mice and marmosets, which likely reflects unique evolutionary constraints on distinct events of neuronal development in the neocortex. The mechanisms underlying neuron specification and maturation are unclear. Here the authors provide an integrated epigenomic and transcriptomic analysis of mouse and marmoset neocortical neuronal classes. Pan-neuronal programs active during early development are more evolutionary conserved but not neuron-specific, whereas pan-neuronal programs active during later stages of maturation are more neuron- and species-specific

Stationary Metrics and Optical Zermelo-Randers-Finsler Geometry

We consider a triality between the Zermelo navigation problem, the geodesic flow on a Finslerian geometry of Randers type, and spacetimes in one dimension higher admitting a timelike conformal Killing vector field. From the latter viewpoint, the data of the Zermelo problem are encoded in a (conformally) Painleve-Gullstrand form of the spacetime metric, whereas the data of the Randers problem are encoded in a stationary generalisation of the usual optical metric. We discuss how the spacetime viewpoint gives a simple and physical perspective on various issues, including how Finsler geometries with constant flag curvature always map to conformally flat spacetimes and that the Finsler condition maps to either a causality condition or it breaks down at an ergo-surface in the spacetime picture. The gauge equivalence in this network of relations is considered as well as the connection to analogue models and the viewpoint of magnetic flows. We provide a variety of examples.Comment: 37 pages, 6 figure

The type numbers of closed geodesics

A short survey on the type numbers of closed geodesics, on applications of the Morse theory to proving the existence of closed geodesics and on the recent progress in applying variational methods to the periodic problem for Finsler and magnetic geodesicsComment: 29 pages, an appendix to the Russian translation of "The calculus of variations in the large" by M. Mors

Kaluza-Klein Consistency, Killing Vectors, and Kahler Spaces

We make a detailed investigation of all spaces Q_{n_1... n_N}^{q_1... q_N} of the form of U(1) bundles over arbitrary products \prod_i CP^{n_i} of complex projective spaces, with arbitrary winding numbers q_i over each factor in the base. Special cases, including Q_{11}^{11} (sometimes known as T^{11}), Q_{111}^{111} and Q_{21}^{32}, are relevant for compactifications of type IIB and D=11 supergravity. Remarkable ``conspiracies'' allow consistent Kaluza-Klein S^5, S^4 and S^7 sphere reductions of these theories that retain all the Yang-Mills fields of the isometry group in a massless truncation. We prove that such conspiracies do not occur for the reductions on the Q_{n_1... n_N}^{q_1... q_N} spaces, and that it is inconsistent to make a massless truncation in which the non-abelian SU(n_i+1) factors in their isometry groups are retained. In the course of proving this we derive many properties of the spaces Q_{n_1... n_N}^{q_1... q_N} of more general utility. In particular, we show that they always admit Einstein metrics, and that the spaces where q_i=(n_i+1)/\ell all admit two Killing spinors. We also obtain an iterative construction for real metrics on CP^n, and construct the Killing vectors on Q_{n_1... n_N}^{q_1... q_N} in terms of scalar eigenfunctions on CP^{n_i}. We derive bounds that allow us to prove that certain Killing-vector identities on spheres, necessary for consistent Kaluza-Klein reductions, are never satisfied on Q_{n_1... n_N}^{q_1... q_N}.Comment: Latex, 43 pages, references added and typos correcte