``Plug and play'' systems for quantum cryptography

We present a time-multiplexed interferometer based on Faraday mirrors, and apply it to quantum key distribution. The interfering pulses follow exactly the same spatial path, ensuring very high stability and self balancing. Use of Faraday mirrors compensates automatically any birefringence effects and polarization dependent losses in the transmitting fiber. First experimental results show a fringe visibility of 0.9984 for a 23km-long interferometer, based on installed telecom fibers.Comment: LaTex, 6 pages, with 2 Postscript figures, Submitted to Applied Physics Letter

Professionalism and the Millbank Tendency: The Political Sociology of New Labour's employees

This article analyses party employees, one of the most under-researched subjects in the study of British political parties. We draw on a blend of quantitative and qualitative data in order to shed light on the social and political profiles of Labour Party staff, and on the question of their professionalisation. The latter theme is developed through a model derived from the sociology of professions. While a relatively limited proportion of party employees conform to the pure ideal-type of professionalism, a considerably greater number manifest enough of the core characteristics of specialisation, commitment, mobility, autonomy and self-regulation to be reasonably described as 'professionals in pursuit of political outcomes'

Isogeometric Boundary-Element Analysis for the Wave-Resistance Problem using T-splines

In this paper we couple collocated Boundary Element Methods (BEM) with unstructured analysis suitable T-spline surfaces for solving a linear Boundary Integral Equation (BIE) arising in the context of a ship-hydrodynamic problem, namely the so-called Neumann-Kelvin problem, following the formulation by Brard (1972) [1] and Baar & Price (1988) [2]. The local-refinement capabilities of the adopted T-spline bases, which are used for representing both the geometry of the hull and approximating the solution of the associated BIE, in accordance with the Isogeometric concept proposed by Hughes et al. (2005) [3], lead to a solver that achieves the same error level for many fewer degrees of freedom as compared with the corresponding NURBS-based Isogeometric-BEM solver recently developed in Belibassakis et al. (2013) [4]. In this connection, this paper makes a step towards integrating modern CAD representations for ship-hulls with hydrodynamic solvers of improved accuracy and efficiency, which is a prerequisite for building efficient ship-hull optimizers

Phase measurements with weak reference pulses

Quantum state discrimination for two coherent states with opposite phases as measured relative to a reference pulse is analyzed as functions of the intensities of both the signal states and of the reference pulse. This problem is relevant for Quantum Key Distribution with phase encoding. We consider both the optimum measurements and simple measurements that require only beamsplitters and photodetectors.Comment: 5 pages, 5 figures. I apologize for this boring pape

A preliminary study of brain macrovascular reactivity in impaired glucose tolerance and type-2 diabetes: Quantitative internal carotid artery blood flow using magnetic resonance phase contrast angiography.

OBJECTIVE: The aims of this study were (1) to examine cerebrovascular autoregulation in subjects with impaired glucose tolerance and type 2 diabetes and (2) to clarify whether cardiovascular autonomic nerve function is associated with abnormal cerebrovascular autoregulation. RESEARCH DESIGN AND METHODS: Totally, 46 subjects were recruited (12 = impaired glucose tolerance, 17 = type 2 diabetes and 17 = healthy volunteers). Arterial blood flow was assessed within the internal carotid artery at baseline and 20 min after intravenous pharmacological stress (1 g acetazolamide), using quantitative magnetic resonance phase-contrast angiography. Internal carotid artery vascular reactivity and pulsatility index was determined. All subjects underwent baroreceptor reflex sensitivity assessment. RESULTS: Subjects with impaired glucose tolerance and type 2 diabetes had significantly lower internal carotid artery vascular reactivity [40.2%(19.8) and 41.5%(18.7)], respectively, compared with healthy volunteers [57.0%(14.2); analysis of variance, p = 0.02]. There was no significant difference in internal carotid artery vascular reactivity between type 2 diabetes and impaired glucose tolerance groups (p = 0.84). There was a significant positive correlation between baroreceptor reflex sensitivity (low frequency:high frequency) with cardiac rhythm variability (ρ = 0.47, p = 0.04) and PI (ρ = 0.46, p = 0.04). CONCLUSION: We have demonstrated significant cerebrovascular haemodynamic abnormalities in subjects with type 2 diabetes and impaired glucose tolerance. This was associated with greater sympathovagal imbalance. This may provide an important mechanistic explanation for increased risk of cerebrovascular disease in diabetes. It also highlights that these abnormalities may already be present in prediabetes

Well-posedness of boundary layer equations for time-dependent flow of non-Newtonian fluids

We consider the flow of an upper convected Maxwell fluid in the limit of high Weissenberg and Reynolds number. In this limit, the no-slip condition cannot be imposed on the solutions. We derive equations for the resulting boundary layer and prove the well-posedness of these equations. A transformation to Lagrangian coordinates is crucial in the argument

Quantum cryptography using balanced homodyne detection

We report an experimental quantum key distribution that utilizes balanced homodyne detection, instead of photon counting, to detect weak pulses of coherent light. Although our scheme inherently has a finite error rate, it allows high-efficiency detection and quantum state measurement of the transmitted light using only conventional devices at room temperature. When the average photon number was 0.1, an error rate of 0.08 and "effective" quantum efficiency of 0.76 were obtained.Comment: Errors in the sentence citing ref.[20] are correcte