From Peace-building towards Development: Opportunities and challenges for Sierra Leone’s future

Simone Datzberger (LSE), Viviane Dittrich (LSE) and Luisa Enria (Oxford) review the recent Sierra Leone research workshop that took place at LSE

Linearized dynamics from the 4-simplex Regge action

We study the relation between the hessian matrix of the riemannian Reggae action on a 4-simplex and linearized quantum gravity. We give an explicit formula for the hessian as a function of the geometry, and show that it has a single zero mode. We then use a 3d lattice model to show that (i) the zero mode is a remnant of the continuum diffeomorphism invariance, and (ii) we recover the complete free graviton propagator in the continuum limit. The results help clarify the structure of the boundary state needed in the recent calculations of the graviton propagator in loop quantum gravity, and in particular its role in fixing the gauge.Comment: 16 (+9 Appendix) pages, 1 figur

Dezentraler Hochwasserschutz - Möglichkeiten der ländlichen Entwicklung zur Unterstützung eines dezentralen Hochwasserschutzes

Die Studie befasst sich mit den Möglichkeiten der ländlichen Entwicklung zur Unterstützung eines dezentralen Hochwasserschutzes. Sie basiert vorrangig auf der Beschaffung, Aufbereitung und Auswertung entsprechender Fachliteratur. Darüber hinaus wurden wasserbauliche- und landeskulturelle Maßnahmen, die im Rahmen der ländlichen Entwicklung in Sachsen realisiert wurden, hinsichtlich ihrer Eignung für den Hochwasserschutz bewertet. Aktuelle Forschungsergebnisse zu erosionsmindernden Bodenbearbeitungsverfahren, die in die Studie einflossen, wurden hausintern vom Fachbereich 4 – Pflanzliche Erzeugung, Referat Bodenkultur, zur Verfügung gestellt. Die zusammengetragenen Inhalte bilden die fachliche Basis zur Anfertigung von Informationsmaterial über die Möglichkeiten der Einflussnahme auf den vorbeugenden Hochwasserschutz durch die Akteure des ländlichen Raumes (landwirtschaftliche Unternehmen, Grundeigentümer, Gemeinden, Zweckverbände, Teilnehmergemeinschaften u. a.)

Emissionsbericht Abwasser - Sechste Bestandsaufnahme der Abwasseremissionen im Freistaat Sachsen 2013/2014

Der Bericht bewertet mit Datenstand 2013/2014 die Belastungen der oberirdischen Gewässer durch kommunale und industrielle Abwassereinleitungen. Pflanzenschutzmittel-Wirkstoffe ohne Biozidanwendung sind in Kläranlagenabläufen messbar. Mit Ausnahme von Azoxystrobin und Glyphosat liegen in der Regel aber keine relevanten Konzentrationen vor. In Mischwasserentlastungen kommen Mikroschadstoffe in ähnlichen Konzentrationen wie in Kläranlagenabläufen vor. Nur in Einzelproben werden deutlich höhere Konzentrationen gefunden. Der Bericht richtet sich an Wasserbehörden, Aufgabenträger der kommunalen Abwasserbeseitigung und Forschungspartner, die sich mit Mikroschadstoffen im Abwasser beschäftigen

Towards the graviton from spinfoams: the complete perturbative expansion of the 3d toy model

We consider an exact expression for the 6j-symbol for the isosceles tetrahedron, involving integrals over SU(2), and use it to write the two-point function of 3d gravity on a single tetrahedron as a group integral. The perturbative expansion of this expression is then performed with respect to the boundary geometry using a simple saddle-point analysis. We derive the complete expansion in inverse powers of the length scale and evaluate explicitly the quantum corrections up to second order. Finally, we use the same method to provide the complete expansion of the isosceles 6j-symbol with the explicit phases at all orders and the next-to-leading correction to the Ponzano-Regge asymptotics.Comment: 16 pages, 3 figs, revtex4, a numerical coefficient corrected in eq (60

Alternative Wirklichkeiten

ALTERNATIVE WIRKLICHKEITEN Alternative Wirklichkeiten / Dittrich, Miro (Rights reserved) ( -

Numerical evidence of regularized correlations in spin foam gravity

We report on the numerical analysis of the area correlations in spin foam gravity on a single 4-simplex considered by Rovelli in PRL 97 (2006) 151301. We compare the asymptotics and confirm the inverse squared distance leading behaviour at large scales. This supports the recent advances on testing the semiclassical limit of the theory. Furthermore, we show that the microscopic discreteness of the theory dynamically suppresses and regularizes the correlations at the Planck scale.Comment: 5 pages, 3 figure

Area-angle variables for general relativity

We introduce a modified Regge calculus for general relativity on a triangulated four dimensional Riemannian manifold where the fundamental variables are areas and a certain class of angles. These variables satisfy constraints which are local in the triangulation. We expect the formulation to have applications to classical discrete gravity and non-perturbative approaches to quantum gravity.Comment: 7 pages, 1 figure. v2 small changes to match published versio

The RNA-binding protein ELAV regulates Hox RNA processing, expression and function within the Drosophila nervous system

The regulated head-to-tail expression of Hox genes provides a coordinate system for the activation of specific programmes of cell differentiation according to axial level. Recent work indicates that Hox expression can be regulated via RNA processing but the underlying mechanisms and biological significance of this form of regulation remain poorly understood. Here we explore these issues within the developing Drosophila central nervous system (CNS). We show that the pan-neural RNA-binding protein (RBP) ELAV (Hu antigen) regulates the RNA processing patterns of the Hox gene Ultrabithorax (Ubx) within the embryonic CNS. Using a combination of biochemical, genetic and imaging approaches we demonstrate that ELAV binds to discrete elements within Ubx RNAs and that its genetic removal reduces Ubx protein expression in the CNS leading to the respecification of cellular subroutines under Ubx control, thus defining for the first time a specific cellular role of ELAV within the developing CNS. Artificial provision of ELAV in glial cells (a cell type that lacks ELAV) promotes Ubx expression, suggesting that ELAVdependent regulation might contribute to cell type-specific Hox expression patterns within the CNS. Finally, we note that expression of abdominal A and Abdominal B is reduced in elav mutant embryos, whereas other Hox genes (Antennapedia) are not affected. Based on these results and the evolutionary conservation of ELAV and Hox genes we propose that the modulation of Hox RNA processing by ELAV serves to adapt the morphogenesis of the CNS to axial level by regulating Hox expression and consequently activating local programmes of neural differentiation

Coupling gauge theory to spinfoam 3d quantum gravity

We construct a spinfoam model for Yang-Mills theory coupled to quantum gravity in three dimensional riemannian spacetime. We define the partition function of the coupled system as a power series in g_0^2 G that can be evaluated order by order using grasping rules and the recoupling theory. With respect to previous attempts in the literature, this model assigns the dynamical variables of gravity and Yang-Mills theory to the same simplices of the spinfoam, and it thus provides transition amplitudes for the spin network states of the canonical theory. For SU(2) Yang-Mills theory we show explicitly that the partition function has a semiclassical limit given by the Regge discretization of the classical Yang-Mills action.Comment: 18 page