On plane gravitational waves in real connection variables

We investigate using plane fronted gravitational wave space-times as model systems to study loop quantization techniques and dispersion relations. In this classical analysis, we start with planar symmetric space-times in the real connection formulation. We reduce via Dirac constraint analysis to a final form with one canonical pair and one constraint, equivalent to the metric and Einstein equations of plane-fronted with parallel rays waves. Due to the symmetries and use of special coordinates general covariance is broken. However, this allows us to simply express the constraints of the consistent system. A recursive construction of Dirac brackets results in non-local brackets, analogous to those of self-dual fields, for the triad variables chosen in this approach.Comment: v2: Matches published version, up to minor stylistic change

Search For Gravitational Waves Through the Electromagnetic Faraday Rotation

A method is given which renders indirect detection of strong gravitational waves possible. This is based on the reflection (collision) of a linearly polarized electromagnetic shock wave from (with) a cross polarized impulsive and shock gravitational waves in accordance with the general theory of relativity. This highly non-linear process induces a detectable Faraday rotation in the polarization vector of the electromagnetic field.Comment: Final version. Minor revision, new figures and references are added. To appear in Physical Review

Asymptotic solutions of glass temperature profiles during steady optical fibre drawing

In this paper we derive realistic simplified models for the high-speed drawing of glass optical fibres via the downdraw method, that capture the fluid dynamics and heat transport in the fibre via conduction, convection and radiative heating. We exploit the small aspect ratio of the fibre and the relative orders of magnitude of the dimensionless parameters that characterize the heat transfer to reduce the problem to one- or two-dimensional systems via asymptotic analysis. The resulting equations may be readily solved numerically and in many cases admit exact analytic solutions. The systematic asymptotic breakdown presented is used to elucidate the relative importance of furnace temperature profile, convection, surface radiation and conduction in each portion of the furnace and the role of each in controlling the glass temperature.\ud \ud The models derived predict many of the qualitative features observed in the real industrial process, such as the glass temperature profile within the furnace and the sharp transition in fibre thickness. The models thus offer a desirable route to quick scenario testing, providing valuable practical information into the dependencies of the solution on the parameters and the dominant heat-transport mechanism

A Generalized Circle Theorem on Zeros of Partition Function at Asymmetric First Order Transitions

We present a generalized circle theorem which includes the Lee-Yang theorem for symmetric transitions as a special case. It is found that zeros of the partition function can be written in terms of discontinuities in the derivatives of the free energy. For asymmetric transitions, the locus of the zeros is tangent to the unit circle at the positive real axis in the thermodynamic limit. For finite-size systems, they lie off the unit circle if the partition functions of the two phases are added up with unequal prefactors. This conclusion is substantiated by explicit calculation of zeros of the partition function for the Blume-Capel model near and at the triple line at low temperatures.Comment: 10 pages, RevTeX. To be published in PRL. 3 Figures will be sent upon reques

The impact of daily emotional demands, job resources and emotional effort on intensive internet use during and after work

Information Communication Technologies (ICTs) have become a popular leisure platform. Psychological recovery during leisure time is vital to replenish resources spent at work. The present diary study comprised a sample of employees with high exposure to emotional demands and integrates the Job Demands-Resources (JD-R) and addiction literature to examine whether engaging intensively on the internet may be conductive or inhibitor to psychological recovery. A total of 84 employees completed four consecutive daily diary survey three times a day comprising 880 data points. Multilevel analysis was used and results confirmed that intensive internet use was higher on days of high demands and low resources for those with higher baseline levels of compulsive use, and intensive use was weaker on days of high resources. Additionally, intensive use increased recovery experience before bed and the morning after only low compulsive users. The opposite was true for more compulsive users. These findings contribute to both JD-R and addiction theory by showing how the unfavourable effects of daily intensive use on recovery can be ameliorated by daily work resources. It also contributes to the recovery literature demonstrating how intensive internet use can trigger recovery and the circumstances under which this happens