An ultrafast reconfigurable nanophotonic switch using wavefront shaping of light in a nonlinear nanomaterial

We demonstrate a new concept for reconfigurable nanophotonic devices exploiting ultrafast nonlinear control of shaped wavefronts in a multimode nanomaterial consisting of semiconductor nanowires. Femtosecond pulsed laser excitation of the nanowire mat is shown to provide an efficient nonlinear mechanism to control both destructive and constructive interference in a shaped wavefront. Modulations of up to 63% are induced by optical pumping, due to a combination of multimode dephasing and induced transient absorption. We show that part of the nonlinear phase dynamics can be inverted to provide a dynamical revival of the wavefront into an optimized spot with up to 18% increase of the peak to background ratio caused by pulsed laser excitation. The concepts of multimode nonlinear switching demonstrated here are generally extendable to other photonic and plasmonic systems and enable new avenues for ultrafast and reconfigurable nanophotonic devices.Comment: 18 pages, 6 figure

Thinking About ... Core Funding

Thinking about... core funding draws on learning from their own and others' research and interviews with key informants from seven charitable foundations providing core funding to shed light on why, when and how to use core funding. Their particular focus is social welfarevoluntary organisations, many of which are local. This part of the voluntary sector relies mainly on two types of income – grants from statutory bodies and fundraising from trusts and foundations. This makes their dependence on core funding from trusts and foundations, and full costrecovery, even more critical

“I can haz emoshuns?”: understanding anthropomorphosis of cats among internet users

The attribution of human-like traits to non-human animals, termed anthropomorphism, can lead to misunderstandings of animal behaviour, which can result in risks to both human and animal wellbeing and welfare. In this paper, we, during an inter-disciplinary collaboration between social computing and animal behaviour researchers, investigated whether a simple image-tagging application could improve the understanding of how people ascribe intentions and emotions to the behaviour of their domestic cats. A web-based application, Tagpuss, was developed to present casual users with photographs drawn from a database of 1631 images of domestic cats and asked them to ascribe an emotion to the cat portrayed in the image. Over five thousand people actively participated in the study in the space of four weeks, generating over 50,000 tags. Results indicate Tagpuss can be used to identify cat behaviours that lay-people find difficult to distinguish. This highlights further expert scientific exploration that focuses on educating cat owners to identify possible problems with their cat’s welfare

Placebo caffeine reduces withdrawal in abstinent coffee drinkers

Background: Expectancies have been shown to play a role in the withdrawal syndrome of many drugs of addiction. However no studies have examined the effects of expectancies across a broad range of caffeine withdrawal symptoms, including craving. Aims: The purpose of the current study was to use caffeine as a model to test the effect of expectancy on withdrawal symptoms, specifically whether the belief that one has ingested caffeine is sufficient to reduce caffeine withdrawal symptoms and cravings in abstinent caffeine drinkers. Methods 24-h abstinent regular coffee drinkers completed the Caffeine Withdrawal Symptom Questionnaire (CWSQ) before and after receiving decaffeinated coffee. Half the participants were led to believe the coffee was regular caffeinated coffee (Told group) and half were told that it was decaffeinated (Low Expectancy group). Results: Participants in the High Expectancy group reported a significantly greater reduction in craving, fatigue, lack of alertness and flu-like feelings factors of the CWSQ than those in the Low Expectancy. Conclusions: These results indicate that the belief that one has consumed caffeine can affect caffeine withdrawal symptoms, especially craving, even when no caffeine has been consumed

Fidelity of the delivery of NHS Health Checks in General Practice

Aim To assess the fidelity of delivery of NHS Health Checks in general practice. Design and Setting Fidelity assessment of video/audio recordings of NHS Health Check consultations conducted in four GP practices across the East of England. Method A secondary analysis of 38 NHS Health Check consultations video or audio recorded as part of a pilot study of introducing discussions surrounding cancer risk into NHS Health Checks. Using a checklist based on the NHS Health Check Best Practice Guidance, fidelity of delivery was assessed as the proportion of key elements completed during the consultations. Results The mean number of elements of the NHS Health Check completed across all consultations was 14.5/18 (80.3%), with a range of 10-17 (55.6-94.4%). The mean fidelity for risk assessment, risk communication and risk management sections was 8.7/10 (86.8%), 4.1/5 (81.6%) and 1.7/3 (56.1%) respectively. Elements with the lowest fidelity were ethnicity assessment (31.6%), family history of cardiovascular disease assessment (65.8%), AUDIT-C communication (34.2%) and dementia risk management (15.8%). Conclusion Although fidelity of delivery was high overall, important elements of the NHS Health Check were being regularly omitted. Opportunities for behaviour change, particularly relating to alcohol consumption and dementia risk management, may be being missed.This study was funded by a Cancer Research UK Prevention Fellowship (C55650/A21464)

Nanomaterial structure determination using XUV diffraction

Diffraction using coherent XUV radiation is used to study the structure of nanophotonic materials, in this case an ordered array of 196nm spheres. Crystal structure and defects are visible, and the nanomaterial dielectric constant determined

Atomic spectral-product representations of molecular electronic structure: metric matrices and atomic-product composition of molecular eigenfunctions

Recent progress is reported in development of ab initio computational methods for the electronic structures of molecules employing the many-electron eigenstates of constituent atoms in spectral-product forms. The approach provides a universal atomic-product description of the electronic structure of matter as an alternative to more commonly employed valence-bond- or molecular-orbital-based representations. The Hamiltonian matrix in this representation is seen to comprise a sum over atomic energies and a pairwise sum over Coulombic interaction terms that depend only on the separations of the individual atomic pairs. Overall electron antisymmetry can be enforced by unitary transformation when appropriate, rather than as a possibly encumbering or unnecessary global constraint. The matrix representative of the antisymmetrizer in the spectral-product basis, which is equivalent to the metric matrix of the corresponding explicitly antisymmetric basis, provides the required transformation to antisymmetric or linearly independent states after Hamiltonian evaluation. Particular attention is focused in the present report on properties of the metric matrix and on the atomic-product compositions of molecular eigenstates as described in the spectral-product representations. Illustrative calculations are reported for simple but prototypically important diatomic (H_2, CH) and triatomic (H_3, CH_2) molecules employing algorithms and computer codes devised recently for this purpose. This particular implementation of the approach combines Slater-orbital-based one- and two-electron integral evaluations, valence-bond constructions of standard tableau functions and matrices, and transformations to atomic eigenstate-product representations. The calculated metric matrices and corresponding potential energy surfaces obtained in this way elucidate a number of aspects of the spectral-product development, including the nature of closure in the representation, the general redundancy or linear dependence of its explicitly antisymmetrized form, the convergence of the apparently disparate atomic-product and explicitly antisymmetrized atomic-product forms to a common invariant subspace, and the nature of a chemical bonding descriptor provided by the atomic-product compositions of molecular eigenstates. Concluding remarks indicate additional studies in progress and the prognosis for performing atomic spectral-product calculations more generally and efficiently

Isotropic contractive scaling of laser written microstructures in vitrified aerogels

A novel route is presented enabling minimization of feature sizes via laser ablative micro-patterning in highly porous silica aerogel monoliths and subsequent viscous sintering. Vitrification yields isotropically contracted silica solids preserving their original stereometric forms. The contraction depends on aerogel structure and porosity and we demonstrate here the first realization of a 3:1 ratio. Surface relief and void micropatterns inscribed in the monolith also undergo isotropic contraction and feature minimization beyond the spatial resolution of their original recording. Experimental results provide clear evidence that embedded void structures undergo contraction larger than the nominal stereometric scaling. This is a demonstration of a generic principle that enables fundamental physical resolution limits to be surpassed, leading to new avenues in micro- and nano-fabrication technologies

What is the functional/organic distinction actually doing in psychiatry and neurology? [version 1; peer review: 3 approved]

The functional-organic distinction aims to distinguish symptoms, signs, and syndromes that can be explained by diagnosable biological changes, from those that cannot. The distinction is central to clinical practice and is a key organising principle in diagnostic systems. Following a pragmatist approach that examines meaning through use, we examine how the functional-organic distinction is deployed and conceptualised in psychiatry and neurology. We note that the conceptual scope of the terms ‘functional’ and ‘organic’ varies considerably by context. Techniques for differentially diagnosing ‘functional’ and ‘organic’ diverge in the strength of evidence they produce as a necessary function of the syndrome in question. Clinicians do not agree on the meaning of the terms and report using them strategically. The distinction often relies on an implied model of ‘zero sum’ causality and encourages classification of syndromes into discrete ‘functional’ and ‘organic’ versions. Although this clearly applies in some instances, this is often in contrast to our best scientific understanding of neuropsychiatric disorders as arising from a dynamic interaction between personal, social and neuropathological factors. We also note ‘functional’ and ‘organic’ have loaded social meanings, creating the potential for social disempowerment. Given this, we argue for a better understanding of how strategic simplification and complex scientific reality limit each other in neuropsychiatric thinking. We also note that the contribution of people who experience the interaction between ‘functional’ and ‘organic’ factors has rarely informed the validity of this distinction and the dilemmas arising from it, and we highlight this as a research priority