Duality, Quotients, and Currents

We study the generalization of $R\to 1/R$ duality to arbitrary conformally invariant sigma models with an isometry. We show that any pair of dual sigma models can be represented as quotients of a self-dual sigma model obtained by gauging different combinations of chiral currents. This observation is used to clarify the interpretation of the generalized duality as a symmetry of conformal field theory. We extend these results to $N=2$ supersymmetric sigma models.Comment: 20 page

O(d,d,Z) Transformations as Automorphisms of the Operator Algebra

We implement the O(d,d,Z) transformations of T-duality as automorphisms of the operator algebras of Conformal Field Theories. This extends these transformations to arbitrary field configurations in the deformation class.Comment: 9 pages, Plain Te

Business Cycles in EU Member States

The paper investigates the business cycle relationships between the EU-15, the EU-11, as well as the EU-core countries for the period 1971 to 1997. Emphasis is put on the question whether there is a synchronization in the national business cycles or not. Using One-way- and Twoway-Anova techniques the results show that country-specific shocks are important to the smaller countries such as Luxembourg, Ireland, Portugal, and Finland. But for most of the EMU-members common shocks are much more important than country-specific shocks. In addition there is no indication of significant differences in the national growth rates, i.e. the European countries do not move along diverging growth paths. Nevertheless, departures over the business cycles are possible because persistence in output growth differs across countries. -- In dem Beitrag wird der konjunkturelle Zusammenhang zwischen den EU-15, den EU-11 und den ?Kern?-EU-Staaten für den Zeitraum von 1971 bis 1997 dahingehend untersucht, ob zwischen den Staaten ein konjunktureller Gleichlauf besteht oder nicht. Eine One-Way- und eine Two-Way-Anova-Analyse zeigt, daß insbesondere für die kleineren Länder länderspezifische Schocks eine beträchtliche Bedeutung haben. Demgegenüber dominieren bei den Kernländern deutlich die ?common shocks?. Da keine länderspezifischen Unterschiede feststellbar waren, kann daraus der Schluß gezogen werden, daß sich die europäischen Staaten entlang eines einheitlichen Wachstumspfades entwickeln. Gleichwohl können kurz- bis mittelfristige Abweichungen eintreten, da die Persistenz im Output für die einzelnen Länder unterschiedlich ist.

Teens and sleep

Sleep is a very important part of the day for everyone. There are many reasons why people should be striving to get the sleep they need. However, many people are skipping out on an hour or two of the recommended time. This presentation is focused on teenage students, how their loss of sleep affects them and why they aren’t getting the amount of sleep they need. ● Teens aged 13–18 should sleep 8–10 hours per day, and 72.7% of high school students don’t get this amount. ● Many negative effects of sleep deprivation. ● Having a normal sleep schedule is just as important as getting enough sleep. ● Light plays a big role in resetting our sleep rhythm. ● Final hours of REM sleep are most important for retaining information. ● On average as children get older they begin to go to sleep later, with the same wake up time. ● Students don’t go to sleep earlier for earlier wake up times

Nomadic work : romance and reality : a response to Barbara Czarniawska’s ‘Nomadic work as life-story plot’

This article takes departure in Barbara Czarniawska’s discussion of ‘Nomadic Work as Life-Story Plot’. It contextualises her analysis of actors’ interpretations of nomadic work with a bi- focal review of the ambiguous realities of these phenomena. Firstly, an examination of key aspects of the socio-economic and political context of nomadic work in global neoliberal economies reveals precarious conditions that cloud romantic interpretations of nomadicity. Secondly, a review of studies of everyday practices of nomadic work shows how neoliberal, but also alternative futures are enacted through creative appropriation of collaborative technologies. One example is the work of digital ‘disaster deck’ volunteers and its potential for the mobilization of ‘rapid, highly localized assistance’ through closer collaboration between a distributed crowd, local communities, and official emergency responders (Starbird and Palen 2013). This and other examples suggest emergent new practices and politics of dwelling in mobility that are focused on sociality and collaboration, straddling virtual and physical commons. The twin critique developed in this response can augment narrative analysis to inform more integrated CSCW innovation that challenges the ‘brave new world of work’

On Conformal Properties of the Dualized Sigma-Models

We have calculated the first-order beta-functions for a sigma-model ( with dilaton) dualized with respect to an arbitrary Lie group that acts without isotropy. We find that non-abelian duality preserves conformal invariance for semi-simple groups, but in general there is an extra contribution to the beta-function proportional to the trace of the structure constants, which cannot be absorbed into an additional dilaton shift. Two particular examples, a Bianchi V cosmological background and the G \otimes G WZW model, are discussed.Comment: 12 pages, LaTeX 2e with fleqn.sty (removed the Stony Brook emblem which was causing problems

Poisson-Lie T-Duality: the Path-Integral Derivation

We formulate Poisson-Lie T-duality in a path-integral manner that allows us to analyze the quantum corrections. Using the path-integral, we rederive the most general form of a Poisson-Lie dualizeable background and the generalized Buscher transformation rules it has to satisfy.Comment: 16 pages, plain LaTeX 2e, one paragraph added to the conclusions; this is the final version accepted by Physics Letters

Numerical Simulations of Pinhole and Single Mode Fibre Spatial Filters for Optical Interferometers

We use a numerical simulation to investigate the effectiveness of pinhole spatial filters at optical/IR interferometers and to compare them with single-mode optical fibre spatial filters and interferometers without spatial filters. We show that fringe visibility measurements in interferometers containing spatial filters are much less affected by changing seeing conditions than equivalent measurements without spatial filters. This reduces visibility calibration uncertainties, and hence can reduce the need for frequent observations of separate astronomical sources for calibration of visibility measurements. We also show that spatial filters can increase the signal-to-noise ratios of visibility measurements and that pinhole filters give signal-to-noise ratios within 17% of values obtained with single-mode fibres for aperture diameters up to 3r_0. Given the simplicity of the use of pinhole filters we suggest that it represents a competitive, if not optimal, technique for spatial filtering in many current and next generation interferometers.Comment: 7 pages, 7 postscript figures. Accepted by MNRA

Municipal commonage and implications for land reform: A profile of commonage users in Philippolis, Free State, South Africa

This paper reports on a survey of municipal commonage users, which was undertaken in Philippolis in the southern Free State, in May 2005. The survey showed that a significant number of commonage users are committed to their farming enterprises, as shown by five proxy indicators: Their readiness to plough their income into their farming enterprises; their sale of livestock; their desire for more land, and their willingness to pay rental to secure such land; their desire to farm on their own; and their desire to own their own land. The paper reflects on the significance of commonage in the context of the South African government’s land reform policy, and argues that commonage can transcend survivalist or subsistence production, and can be used as a “stepping stone” for emergent farmers to access their own land parcels. Finally, the paper argues that, if commonage is to become a key part in a “step-up” strategy of land reform, then appropriately sized land parcels should be made available for commonage users, to enable them to “exit” from commonage use and invest in smallholdings or small farms.Land Economics/Use,

Non-Abelian Axial-Vector Duality: a Geometric Description

We give a geometric characterization of the quasi axial-vector (Kiritsis-Obers) target space duality in the spirit of the bi-algebra (Klimcik-Severa) approach. We show that the sigma-models constructed by taking quotients have non-abelian chiral currents that obey "non-commutative conservation laws" and provide the criterion for a sigma-model to have a dual using the axial-vector procedure.Comment: 10 pages, plain LaTeX 2e. The paper (and conclusions) is significantly revised due to a misprint in one of the references. If you read the old version, you SHOULD get this on