Substituted BEDT-TTF derivatives: synthesis, chirality, properties and potential applications

The increasing availability of functionalized BEDT-TTF derivatives in both racemic and enantiopure forms opens up great opportunities for preparing multifunctional materials and chiral conducting systems in the form of crystals, thin films and polymers. Functionalities such as amino and carboxyl will allow attachment to other molecular systems, while intermolecular interactions between substituents, e.g. hydrogen bonding and halegon- - - halegon interactions, provides additional tools for designing solid state radical cation structures. In this review the syntheses of substituted derivatives of BEDT-TTF and closely related donors are surveyed, along with the structures and properties of the radical cation salts so far prepared, as a stimulus for future application of these versatile and attractive molecules. Particular attention is paid to the preparation of single enantiomers, and to the stereochemical consequences of the synthetic procedures

The conceptualisation and measurement of DSM-5 Internet Gaming Disorder: the development of the IGD-20 Test

Background: Over the last decade, there has been growing concern about ‘gaming addiction’ and its widely documented detrimental impacts on a minority of individuals that play excessively. The latest (fifth) edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-5) included nine criteria for the potential diagnosis of Internet Gaming Disorder (IGD) and noted that it was a condition that warranted further empirical study. Aim: The main aim of this study was to develop a valid and reliable standardised psychometrically robust tool in addition to providing empirically supported cut-off points. Methods: A sample of 1003 gamers (85.2% males; mean age 26 years) from 57 different countries were recruited via online gaming forums. Validity was assessed by confirmatory factor analysis (CFA), criterion-related validity, and concurrent validity. Latent profile analysis was also carried to distinguish disordered gamers from non-disordered gamers. Sensitivity and specificity analyses were performed to determine an empirical cut-off for the test. Results: The CFA confirmed the viability of IGD-20 Test with a six-factor structure (salience, mood modification, tolerance, withdrawal, conflict and relapse) for the assessment of IGD according to the nine criteria from DSM-5. The IGD-20 Test proved to be valid and reliable. According to the latent profile analysis, 5.3% of the total participants were classed as disordered gamers. Additionally, an optimal empirical cut-off of 71 points (out of 100) seemed to be adequate according to the sensitivity and specificity analyses carried

Clustering and correlates of screen-time and eating behaviours among young children

Background: Screen-time and unhealthy dietary behaviours are highly pervasive in young children and evidence suggests that these behaviours often co-occur and are associated. Identifying clusters of unhealthy behaviours, and their influences early in childhood, can assist in the development of targeted preventive interventions. The purpose of this study was to examine the sociodemographic, behavioural, and home physical environmental correlates of co-occurring screen-time and unhealthy eating behaviours and to assess the clustering of screen-time and unhealthy dietary behaviours in young children. Methods: Parents of 126 children, from the UK, aged 5–6 years (49% boys) completed a questionnaire which assessed their child’s screen-time (ST), fruit and vegetable (FV), and energy-dense (ED) snack consumption. Categories of health behaviours were created based on frequencies of children meeting recommendations for FV and ST and median splits of frequencies for ED snacks. Parents reported on their own behaviours (ST, FV, and ED snack consumption), how often they ate meals and watched TV with their child, and on the availability and accessibility of foods within the home. An observed over expected ratio (O/E) was used to assess behavioural clustering. Multivariable multinomial logistic regression was used to examine correlates of behaviour patterns. Results: Approximately 25% of children had two or three health risk behaviours. Correlates consistently associated with clusters included parental income, eating meals at the TV, parental ST and ED snack food consumption, and home availability of ED snack foods. Observed over expected ratios were close to 1 and ranged from 0.78 to 1.43. The three-risk behaviour combination of insufficient FV consumption, high ED snack consumption, and excessive ST occurred more frequently than expected (1.23 (95% CI 0.89, 1.58)). Conclusions: ST and unhealthy dietary behaviours cluster in children as young as 5 years of age and parents’ own behaviours appear to be important influencing factors. Further research into the development of behavioural clustering in young children to identify and further understand the mechanisms underlying the synergy among health behaviours is needed. Feasibility interventions promoting reductions in both screen-time and unhealthy dietary behaviours reciprocally, while simultaneously focusing on changing parental behaviours, are warranted

Clustering and correlates of screen-time and eating behaviours among young adolescents

Background: Screen-time and eating behaviours are associated in adolescents, but few studies have examined the clustering of these health behaviours in this age group. The identification of clustered health behaviours, and influences on adolescents’ clustered health behaviours, at the time when they are most likely to become habitual, is important for intervention design. The purpose of this study was to assess the prevalence and clustering of health behaviours in adolescents, and examine the sociodemographic, individual, behavioural, and home social and physical environmental correlates of clustered health behaviours. Methods: Adolescents aged 11–12 years (n=527, 48% boys) completed a questionnaire during class-time which assessed screen-time (ST), fruit and vegetable (FV), and energy-dense (ED) snack consumption using a Food Frequency Questionnaire. Health behaviours were categorised into high and low frequencies based on recommendations for FV and ST and median splits for ED snacks. Adolescents reported on their habits, self-efficacy, eating at the television (TV), eating and watching TV together with parents, restrictive parenting practices, and the availability and accessibility of foods within the home. Behavioural clustering was assessed using an observed over expected ratio (O/E). Correlates of clustered behaviours were examined using multivariate multinomial logistic regression. Results: Approximately 70% reported having two or three health risk behaviours. Overall, O/E ratios were close to 1, which indicates clustering. The three risk behaviour combination of low FV, high ED, and high ST occurred more frequently than expected (O/E ratio = 1.06 95% CI 1.01, 1.15. Individual, behavioural, and social and physical home environmental correlates were differentially associated with behavioural clusters. Correlates consistently associated with clusters included eating ED snacks while watching TV, eating at the TV with parents, and the availability and accessibility of ED snack foods within the home. Conclusions: There is a high prevalence of screen time and unhealthy eating, and screen time is coupled with unhealthy dietary behaviours. Strategies and policies are required that simultaneously address reductions in screen time and changes to habitual dietary patterns, such as TV snacking and snack availability and accessibility. These may require a combination of individual, social and environmental changes alongside conscious and more automatic (nudging) strategies

Magnetic-field-induced charge redistribution in disordered graphene double quantum dots

We have studied the transport properties of a large graphene double quantum dot under the influence of a background disorder potential and a magnetic field. At low temperatures, the evolution of the charge-stability diagram as a function of the B field is investigated up to 10 T. Our results indicate that the charging energy of the quantum dot is reduced, and hence the effective size of the dot increases at a high magnetic field. We provide an explanation of our results using a tight-binding model, which describes the charge redistribution in a disordered graphene quantum dot via the formation of Landau levels and edge states. Our model suggests that the tunnel barriers separating different electron/hole puddles in a dot become transparent at high B fields, resulting in the charge delocalization and reduced charging energy observed experimentally.This work was financially supported by the European GRAND project (ICT/FET, Contract No. 215752) and EPSRC

Quantum photonics hybrid integration platform

Fundamental to integrated photonic quantum computing is an on-chip method for routing and modulating quantum light emission. We demonstrate a hybrid integration platform consisting of arbitrarily designed waveguide circuits and single-photon sources. InAs quantum dots (QD) embedded in GaAs are bonded to a SiON waveguide chip such that the QD emission is coupled to the waveguide mode. The waveguides are SiON core embedded in a SiO2 cladding. A tuneable Mach Zehnder interferometer (MZI) modulates the emission between two output ports and can act as a path-encoded qubit preparation device. The single-photon nature of the emission was verified using the on-chip MZI as a beamsplitter in a Hanbury Brown and Twiss measurement.E.M. and T.M. acknowledge support by the Marie Curie Actions within the Seventh Framework Programme for Research of the European Commission, under the Initial Training Network PICQUE (Grant No. 608062). F.F. acknowledges support from both the EPSRC and Toshiba Research Europe Ltd., Cambridge. J.L. acknowledges support from both the EPSRC CDT in Photonic Systems Development and Toshiba Research Europe Ltd., Cambridge. The authors acknowledge funding from the EPSRC for the MBE system used in the production of the QD samples.This is the final version of the article. It first appeared from AIP via http://dx.doi.org/10.1063/1.493502

Explicit de Sitter Flux Vacua for Global String Models with Chiral Matter

We address the open question of performing an explicit stabilisation of all closed string moduli (including dilaton, complex structure and Kaehler moduli) in fluxed type IIB Calabi-Yau compactifications with chiral matter. Using toric geometry we construct Calabi-Yau manifolds with del Pezzo singularities. D-branes located at such singularities can support the Standard Model gauge group and matter content. In order to control complex structure moduli stabilisation we consider Calabi-Yau manifolds which exhibit a discrete symmetry that reduces the effective number of complex structure moduli. We calculate the corresponding periods in the symplectic basis of invariant three-cycles and find explicit flux vacua for concrete examples. We compute the values of the flux superpotential and the string coupling at these vacua. Starting from these explicit complex structure solutions, we obtain AdS and dS minima where the Kaehler moduli are stabilised by a mixture of D-terms, non-perturbative and perturbative alpha'-corrections as in the LARGE Volume Scenario. In the considered example the visible sector lives at a dP_6 singularity which can be higgsed to the phenomenologically interesting class of models at the dP_3 singularity.Comment: 49 pages, 5 figures; v2: references adde

Screening for breast cancer : medicalization, visualization and the embodied experience

Women’s perspectives on breast screening (mammography and breast awareness) were explored in interviews with midlife women sampled for diversity of background and health experience. Attending mammography screening was considered a social obligation despite women’s fears and experiences of discomfort. Women gave considerable legitimacy to mammography visualizations of the breast, and the expert interpretation of these. In comparison, women lacked confidence in breast awareness practices, directly comparing their sensory capabilities with those of the mammogram, although mammography screening did not substitute breast awareness in a straightforward way. The authors argue that reliance on visualizing technology may create a fragmented sense of the body, separating the at risk breast from embodied experience

Nonlinear spectra of spinons and holons in short GaAs quantum wires.

One-dimensional electronic fluids are peculiar conducting systems, where the fundamental role of interactions leads to exotic, emergent phenomena, such as spin-charge (spinon-holon) separation. The distinct low-energy properties of these 1D metals are successfully described within the theory of linear Luttinger liquids, but the challenging task of describing their high-energy nonlinear properties has long remained elusive. Recently, novel theoretical approaches accounting for nonlinearity have been developed, yet the rich phenomenology that they predict remains barely explored experimentally. Here, we probe the nonlinear spectral characteristics of short GaAs quantum wires by tunnelling spectroscopy, using an advanced device consisting of 6000 wires. We find evidence for the existence of an inverted (spinon) shadow band in the main region of the particle sector, one of the central predictions of the new nonlinear theories. A (holon) band with reduced effective mass is clearly visible in the particle sector at high energies.This work was supported by the UK EPSRC [Grant Nos. EP/J01690X/1 and EP/J016888/1].This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/NCOMMS12784

Measurement and control of electron wave packets from a single-electron source

We report an experimental technique to measure and manipulate the arrival-time and energy distributions of electrons emitted from a semiconductor electron pump, operated as both a singleelectron source and a two-electron source. Using an energy-selective detector whose transmission we control on picosecond time scales, we can measure directly the electron arrival-time distribution and we determine the upper bound to the distribution width to be 30 ps. We study the effects of modifying the shape of the voltage waveform that drives the electron pump, and show that our results can be explained by a tunneling model of the emission mechanism. This information was in turn used to control the emission-time difference and energy gap between a pair of electrons.This research was supported by the UK Department for Business, Innovation and Skills, the National Physical Laboratory’s Strategic Research Programme and the UK Engineering and Physical Sciences Research Council. V.K. has been supported by the Latvian Council of Science within research project no. 146/2012.This is the author accepted manuscript. The final version is available from APS via http://dx.doi.org/10.1103/PhysRevB.92.12530