Characterising latency for AO optical sensors: An implementation

The latency of electro-optical components is of high importance in the design of Adaptive Optics systems, as it limits the performance of the control loop. There exists a need for a latency measurement method that can be constructed with simple components found in most Adaptive Optics labs that still provides a measurement accurate to sub-microseconds. Through a combination of research and experimentation, potential methodologies were investigated with the aim of producing reliable latency measurements. This document will discuss one such method, involving coupling a LED pulse output and detected pulse input signals to the same clock for easy comparison. For this method, a proof-of-concept was developed using MATLAB and small analogue electronics, and the performance characterised. This characterisation showed that although there is some merit to the method, improvements are necessary to increase the precision of the measurement to a level usable in Adaptive Optics systems

Modeling the Daily Variations of the Coronal X-ray Spectral Irradiance with Two Temperatures and Two Emission Measures

The Miniature X-ray Solar Spectrometer (MinXSS-1) CubeSat observed solar X-rays between 0.5 and 10 keV. A two-temperature, two-emission measure model is fit to each daily averaged spectrum. These daily average temperatures and emission measures are plotted against the corresponding daily solar 10.7 cm radio flux (F10.7) value and a linear correlation is found between each that we call the Schwab Woods Mason (SWM) model. The linear trends show that one can estimate the solar spectrum between 0.5 keV and 10 keV based on the F10.7 measurement alone. The cooler temperature component of this model represents the quiescent sun contribution to the spectra and is essentially independent of solar activity, meaning the daily average quiescent sun is accurately described by a single temperature (1.70 MK) regardless of solar intensity and only the emission measure corresponding to this temperature needs to be adjusted for higher or lower solar intensity. The warmer temperature component is shown to represent active region contributions to the spectra and varies between 5 MK to 6 MK. GOES XRS-B data between 1-8 Angstroms is used to validate this model and it is found that the ratio between the SWM model irradiance and the GOES XRS-B irradiance is close to unity on average. MinXSS-1 spectra during quiescent solar conditions have very low counts beyond around 3 keV. The SWM model can generate MinXSS-1 or DAXSS spectra at very high spectral resolution and with extended energy ranges to fill in gaps between measurements and extend predictions back to 1947

Separable approximation for mixed states of composite quantum systems

We describe a purely algebraic method for finding the best separable approximation to a mixed state of a composite 2x2 quantum system, consisting of a decomposition of the state into a linear combination of a mixed separable part and a pure entangled one. We prove that, in a generic case, the weight of the pure part in the decomposition equals the concurrence of the state.Comment: 13 pages, no figures; minor changes; accepted for publication in PR

Episodic warming of near-bottom waters under the Arctic sea ice on the central Laptev Sea shelf

A multiyear mooring record (2007–2014) and satellite imagery highlight the strong temperature variability and unique hydrographic nature of the Laptev Sea. This Arctic shelf is a key region for river discharge and sea ice formation and export and includes submarine permafrost and methane deposits, which emphasizes the need to understand the thermal variability near the seafloor. Recent years were characterized by early ice retreat and a warming near-shore environment. However, warming was not observed on the deeper shelf until year-round under-ice measurements recorded unprecedented warm near-bottom waters of +0.6°C in winter 2012/2013, just after the Arctic sea ice extent featured a record minimum. In the Laptev Sea, early ice retreat in 2012 combined with Lena River heat and solar radiation produced anomalously warm summer surface waters, which were vertically mixed, trapped in the pycnocline, and subsequently transferred toward the bottom until the water column cooled when brine rejection eroded stratification

Using mentoring to improve the foundation placement in psychiatry: review of literature and a practical example

In the past few years, mentoring in clinical settings has attracted the attention of medical educators, clinicians, managers, and policy makers. Most of the Royal Colleges of medical and surgical specialities have some form of mentoring schemes and various regional divisions of Health Education England support mentoring and coaching in the workplace. Despite the importance of this topic and the great need to provide more support to doctors in recent times, there is a paucity of literature on examples of mentoring schemes in clinical settings and practicalities of setting up such schemes in hospitals. This paper describes the implementation of a mentoring scheme in a large mental health trust in the UK to support junior doctors and the issues involved in creating such scheme. We hope that this article will be useful to clinicians who would like to start similar schemes in their workplace