Robust quantum parameter estimation: coherent magnetometry with feedback

We describe the formalism for optimally estimating and controlling both the state of a spin ensemble and a scalar magnetic field with information obtained from a continuous quantum limited measurement of the spin precession due to the field. The full quantum parameter estimation model is reduced to a simplified equivalent representation to which classical estimation and control theory is applied. We consider both the tracking of static and fluctuating fields in the transient and steady state regimes. By using feedback control, the field estimation can be made robust to uncertainty about the total spin number

Efficient feedback controllers for continuous-time quantum error correction

We present an efficient approach to continuous-time quantum error correction that extends the low-dimensional quantum filtering methodology developed by van Handel and Mabuchi [quant-ph/0511221 (2005)] to include error recovery operations in the form of real-time quantum feedback. We expect this paradigm to be useful for systems in which error recovery operations cannot be applied instantaneously. While we could not find an exact low-dimensional filter that combined both continuous syndrome measurement and a feedback Hamiltonian appropriate for error recovery, we developed an approximate reduced-dimensional model to do so. Simulations of the five-qubit code subjected to the symmetric depolarizing channel suggests that error correction based on our approximate filter performs essentially identically to correction based on an exact quantum dynamical model

The Customer Is Always Right? Resistance from College Students to E-Books as Textbooks

As the reign of the e-book continues to expand, more emphasis is being placed on e-books within the academic community, particularly with the idea of e-textbooks. Conventional wisdom suggests that in the same way the e-books now hold a major share of the book market, e-textbooks will continue to expand until they are also the dominant mode of textbook publishing. It also would be expected that current students in colleges and universities, who are usually described as digital natives, would embrace this technology wholeheartedly, but indications from currently-available research suggest the situation may not be as clear-cut. Recent studies have focused on the perceived impediments to e-textbook use from the student‟s point of view. Collectively, they provide some guidance for appropriate modification of the technology, and suggest ways in which libraries and instructors might market e-textbooks more effectively

Malaria: an update on treatment of adults in non-endemic countries.

Every year people die from malaria in Britain and other industrialised countries. Most of these deaths are avoidable: they occur because a patient or doctor has underestimated the severity of the disease or has not considered the diagnosis early enough. This article provides the essential facts on treating malaria in adults in a non-endemic setting and is based on the best available evidenc

A novel liver specific isoform of the rat LAR transcript is expressed as a truncated isoform encoded from a 5'UTR located within intron 11

<p>Abstract</p> <p>Background</p> <p>The leukocyte common antigen related receptor (LAR) protein has been shown to modulate the signal transduction of a number of different growth factors, including insulin and insulin-like growth factor 1. Splice variants exhibit differing roles and are expressed according to tissue type and developmental stage.</p> <p>Results</p> <p>Using 5'RACE, we identified a 5'UTR within intron 11 of the rat LAR gene. We demonstrated that this gives rise to a novel isoform of the LAR transcript encoded from the identified region within intron 11. By priming across the site from exon 11 to exon 15 we show that the novel 5'UTR is not represented in the full-length transcript and thus, it produces a truncated form of the LAR mRNA. We examined the tissue distribution of this novel isoform and found it to be exclusively expressed in liver. We additionally identified a liver specific 150 kDa band with western blotting which we propose may represent the protein product of the novel transcript. Luciferase assays showed the region immediately upstream of the 5'UTR to possesses considerable promoter activity and that this may be conferred by the presence of a number of putative binding sites for liver enriched transcription factors.</p> <p>Conclusion</p> <p>In summary, we describe a novel, liver specific, truncated isoform of the LAR transcript transcribed under the control of an intronic promoter, potentially representing a previously unidentified modulator of hepatic insulin signalling.</p

Nonbacterial Thrombotic Mitral Valve Endocarditis Presenting as Embolic Stroke in a Young Patient with Lupus and Anti-phospholipid Syndrome

A 37-year-old man on systemic immunosuppression for clinically and biochemically quiescent lupus nephritis, presented with left hemiparesis. Brain MRI was concerning for right sided embolic stroke. Workup was negative for atrial fibrillation, deep venous thrombosis, and heart failure. Transesophageal echocardiogram was remarkable for fixed mitral valve leaflet echodensities. In the absence of bacteremia and systemic signs of infection, and with a history of lupus, small vegetations on atrial and ventricular sides of mitral valve leaflets are suggestive of nonbacterial thrombotic endocarditis. Nonbacterial thrombotic vegetations are composed of fibrin deposits on otherwise-healthy valves. Mainstay of treatment is therapeutic anticoagulation with clinical and echocardiographic surveillance for moderate-severe mitral regurgitation

Adaptive learning can result in a failure to profit from good conditions: implications for understanding depression.

Published onlineThis is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/emph/eov009BACKGROUND AND OBJECTIVES: Depression is a major medical problem diagnosed in an increasing proportion of people and for which commonly prescribed psychoactive drugs are frequently ineffective. Development of treatment options may be facilitated by an evolutionary perspective; several adaptive reasons for proneness to depression have been proposed. A common feature of many explanations is that depressive behaviour is a way to avoid costly effort where benefits are small and/or unlikely. However, this viewpoint fails to explain why low mood persists when the situation improves. We investigate whether a behavioural rule that is adapted to a stochastically changing world can cause inactivity which appears similar to the effect of depression, in that it persists after the situation has improved. METHODOLOGY: We develop an adaptive learning model in which an individual has repeated choices of whether to invest costly effort that may result in a net benefit. Investing effort also provides information about the current conditions and rates of change of the conditions. RESULTS: An individual following the optimal behavioural strategy may sometimes remain inactive when conditions are favourable (i.e. when it would be better to invest effort) when it is poorly informed about the current environmental state. Initially benign conditions can predispose an individual to inactivity after a relatively brief period of negative experiences. CONCLUSIONS AND IMPLICATIONS: Our approach suggests that the antecedent factors causing depressed behaviour could go much further back in an individual s history than is currently appreciated. The insights from our approach have implications for the ongoing debate about best treatment options for patients with depressive symptoms.This work was supported by the European Research Council (Evomech Advanced Grant 250 209 to A.I.H.)