Heat transfer coefficient saturation in superconducting Nb tunnel junctions contacted to a NbTiN circuit and an Au energy relaxation layer

In this paper we present the experimental realization of a Nb tunnel junction connected to a high-gap superconducting NbTiN embedding circuit. We investigate relaxation of nonequilibrium quasiparticles in a small volume Au layer between the Nb tunnel junction and the NbTiN circuit. We find a saturation in the effective heat-transfer coefficient consistent with a simple theoretical model. This saturation is determined by the thickness of the Au layer. Our findings are important for the design of the ideal Au energy relaxation layer for practical SIS heterodyne mixers and we suggest two geometries, one, using a circular Au layer and, two, using a half-circular Au layer. Our work is concluded with an outlook of our future experiments.Comment: Applied Superconductivity Conference 201

Early contingentnegative variation of the EEG and attentional flexibility are reduced in hypotension

This study explored the question as to whether hypotension is related to decreased attentional performance and reduced cortical activation. A total of 50 females aged 19 44 years participated in the study. Attentional performance was assessed using three subtests of the Attentional and Cognitive Efficiency (ACE) battery. Contingent negative variation (CNV) as a measure of cortical activation was registered during a constant fore-period reaction time paradigm: two conditions were defined using tones as S1 (80 or 60 dB) and S2 (70 dB). The following results were obtained. Hypotensive patients performed significantly more poorly on one subtest of the ACE, which indicates a reduced speed for switching from a routine to a controlled response (quantifying attentional flexibility). They also had longer reaction times and revealed a significantly smaller amplitude of the early CNV component. In addition, a significant correlation was observed between systolic blood pressure and the amplitude of the early CNV component. The data support previous findings that hypotension can be related to lowered cortical activation and indicate that specific aspects of attentional performance might be negatively affected by hypotension

Target Controlled infusion of opioids for bariatric surgery and morphine loading dose

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Reduction by Lie Group symmetries in diffeomorphic image registration and deformation modelling

We survey the role of reduction by symmetry in the large deformation diffeomorphic metric mapping framework for registration of a variety of data types (landmarks, curves, surfaces, images and higher-order derivative data). Particle relabelling symmetry allows the equations of motion to be reduced to the Lie algebra allowing the equations to be written purely in terms of the Eulerian velocity field. As a second use of symmetry, the infinite dimensional problem of finding correspondences between objects can be reduced for a range of concrete data types, resulting in compact representations of shape and spatial structure. Using reduction by symmetry, we describe these models in a common theoretical framework that draws on links between the registration problem and geometric mechanics. We outline these constructions and further cases where reduction by symmetry promises new approaches to the registration of complex data types

Super-orbital re-entry in Australia - laboratory measurement, simulation and flight observation

There are large uncertainties in the aerothermodynamic modelling of super-orbital re-entry which impact the design of spacecraft thermal protection systems (TPS). Aspects of the thermal environment of super-orbital re-entry flows can be simulated in the laboratory using arc- and plasma jet facilities and these devices are regularly used for TPS certification work [5]. Another laboratory device which is capable of simulating certain critical features of both the aero and thermal environment of super-orbital re-entry is the expansion tube, and three such facilities have been operating at the University of Queensland in recent years[10]. Despite some success, wind tunnel tests do not achieve full simulation, however, a virtually complete physical simulation of particular re-entry conditions can be obtained from dedicated flight testing, and the Apollo era FIRE II flight experiment [2] is the premier example which still forms an important benchmark for modern simulations. Dedicated super-orbital flight testing is generally considered too expensive today, and there is a reluctance to incorporate substantial instrumentation for aerothermal diagnostics into existing missions since it may compromise primary mission objectives. An alternative approach to on-board flight measurements, with demonstrated success particularly in the ‘Stardust’ sample return mission, is remote observation of spectral emissions from the capsule and shock layer [8]. JAXA’s ‘Hayabusa’ sample return capsule provides a recent super-orbital reentry example through which we illustrate contributions in three areas: (1) physical simulation of super-orbital re-entry conditions in the laboratory; (2) computational simulation of such flows; and (3) remote acquisition of optical emissions from a super-orbital re entry event

Quantum theory of single-photon nonlinearities generated by ensembles of emitters

The achievement of sufficiently fast interactions between two optical fields at the few-photon level would provide a key enabler for a broad range of quantum technologies. One critical hurdle in this endeavor is the lack of a comprehensive quantum theory of the generation of nonlinearities by ensembles of emitters. Distinct approaches applicable to different regimes have yielded important insights: i) a semiclassical approach reveals that, for many-photon coherent fields, the contributions of independent emitters add independently allowing ensembles to produce strong optical nonlinearities via EIT; ii) a quantum analysis has shown that in the few-photon regime collective coupling effects prevent ensembles from inducing these strong nonlinearities. Rather surprisingly, experimental results with around twenty photons are in line with the semi-classical predictions. Theoretical analysis has been fragmented due to the difficulty of treating nonlinear many-body quantum systems. Here we are able to solve this problem by constructing a powerful theory of the generation of optical nonlinearities by single emitters and ensembles. The key to this construction is the application of perturbation theory to perturbations generated by subsystems. This theory reveals critical properties of ensembles that have long been obscure. The most remarkable of these is the discovery that quantum effects prevent ensembles generating single-photon nonlinearities only within the rotating-wave regime; outside this regime single-photon nonlinearities scale as the number of emitters. The theory we present here also provides an efficient way to calculate nonlinearities for arbitrary multi-level driving schemes, and we expect that it will prove a powerful foundation for further advances in this area.Comment: 21 pages, Revtex4-2, 4 png figures, 1 supplement fil