Electrical excitation of surface plasmons

We exploit a plasmon mediated two-step momentum downconversion scheme to convert low-energy tunneling electrons into propagating photons. Surface plasmon polaritons (SPPs) propagating along an extended gold nanowire are excited on one end by low-energy electron tunneling and are then converted to free-propagating photons at the other end. The separation of excitation and outcoupling proofs that tunneling electrons excite gap plasmons that subsequently couple to propagating plasmons. Our work shows that electron tunneling provides a non-optical, voltage-controlled and low-energy pathway for launching SPPs in nanostructures, such as plasmonic waveguide

Fabric anisotropy & DEM informed two-surface hyperplasticity : constitutive formulation, asymptotic states & experimental validation.

In geotechnical analysis continuum idealisations of the bulk material still provide the most appropriate approach for engineers designing large-scale structures. In this area, the most successful framework for describing the behaviour of soils is Critical State (CS) soil mechanics. However, the findings from discrete element method (DEM) analysis, such as the uniqueness of the CS, can provide invaluable information in the development such models. This paper details the key concepts behind a two-surface hyperplasticity model (?) whose development was informed by recent DEM findings on the uniqueness of the CS. Asymptotic states of the model will be confirmed and the DEM-continuum-experimental loop will be closed through comparison of the developed model with experimental data on coarse-grained particulate media. This will demonstrate, that providing the previous stress history is accounted for, the proposed model is suitable for a variety of particulate media

Hydrodynamic object recognition using pressure sensing

Hydrodynamic sensing is instrumental to fish and some amphibians. It also represents, for underwater vehicles, an alternative way of sensing the fluid environment when visual and acoustic sensing are limited. To assess the effectiveness of hydrodynamic sensing and gain insight into its capabilities and limitations, we investigated the forward and inverse problem of detection and identification, using the hydrodynamic pressure in the neighbourhood, of a stationary obstacle described using a general shape representation. Based on conformal mapping and a general normalization procedure, our obstacle representation accounts for all specific features of progressive perceptual hydrodynamic imaging reported experimentally. Size, location and shape are encoded separately. The shape representation rests upon an asymptotic series which embodies the progressive character of hydrodynamic imaging through pressure sensing. A dynamic filtering method is used to invert noisy nonlinear pressure signals for the shape parameters. The results highlight the dependence of the sensitivity of hydrodynamic sensing not only on the relative distance to the disturbance but also its bearing

Operational research on a high-T <inf>c</inf> rectifier-type superconducting flux pump

High-T$_{c}$ superconducting (HTS) flux pumps are capable of injecting flux into a superconducting circuit, which can achieve persistent current operation for HTS magnets. In this paper, we studied the operation of a rectifier-type HTS flux pump. The flux pump employs a transformer to generate high alternating current in its secondary winding, which is connected to an HTS load shorted by an HTS bridge. A high frequency ac field is intermittently applied perpendicular to the bridge, thus, generating flux flow. The dynamic resistance caused by the flux flow 'rectifies' the secondary current, resulting in a direct current in the load. We have found that the final load current can easily be controlled by changing the phase difference between the secondary current and the bridge field. The bridge field of frequency ranging from 10 to 40 Hz and magnitude ranging from 0 to 0.66 T was tested. Flux pumping was observed for field magnitudes of 50 mT or above. We have found that both higher field magnitude and higher field frequency result in a faster pumping speed and a higher final load current. This can be attributed to the influence of dynamic resistance. The dynamic resistance measured in the flux pump is comparable with the theoretical calculation. The experimental results fully support a first order circuit model. The flux pump is much more controllable than the traveling wave flux pumps based on permanent magnets, which makes it promising for practical use.JG would like to acknowledge Cambridge Trust for offering a Cambridge International Scholarship to support his study in Cambridge.This is the author accepted manuscript. The final version is available from the Institute of Physics via http://dx.doi.org/10.1088/0953-2048/29/3/03501

Amygdala Perfusion Is Predicted by Its Functional Connectivity with the Ventromedial Prefrontal Cortex and Negative Affect

Background: Previous studies have shown that the activity of the amygdala is elevated in people experiencing clinical and subclinical levels of anxiety and depression (negative affect). It has been proposed that a reduction in inhibitory input to the amygdala from the prefrontal cortex and resultant over-activity of the amygdala underlies this association. Prior studies have found relationships between negative affect and 1) amygdala over-activity and 2) reduced amygdala-prefrontal connectivity. However, it is not known whether elevated amygdala activity is associated with decreased amygdala-prefrontal connectivity during negative affect states. Methods: Here we used resting-state arterial spin labeling (ASL) and blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) in combination to test this model, measuring the activity (regional cerebral blood flow, rCBF) and functional connectivity (correlated fluctuations in the BOLD signal) of one subregion of the amygdala with strong connections with the prefrontal cortex, the basolateral nucleus (BLA), and subsyndromal anxiety levels in 38 healthy subjects. Results: BLA rCBF was strongly correlated with anxiety levels. Moreover, both BLA rCBF and anxiety were inversely correlated with the strength of the functional coupling of the BLA with the caudal ventromedial prefrontal cortex. Lastly, BLA perfusion was found to be a mediator of the relationship between BLA-prefrontal connectivity and anxiety. Conclusions: These results show that both perfusion of the BLA and a measure of its functional coupling with the prefrontal cortex directly index anxiety levels in healthy subjects, and that low BLA-prefrontal connectivity may lead to increased BLA activity and resulting anxiety. Thus, these data provide key evidence for an often-cited circuitry model of negative affect, using a novel, multi-modal imaging approach

Experimental study of the normal zone propagation velocity in double-layer 2G-HTS wires by thermal and electrical methods

The Normal Zone Propagation Velocity (NZPV) of a double-layer second generation (2G) high temperature superconducting (HTS) wire manufactured by American Superconductor has been measured by electrical and thermal methods, and the results have been compared and discussed. The NZPV values determined by the voltage traces are ranging from 3.8 mm/s at 0.4 Ic to 19.2 mm/s at 0.9 Ic; while from 5.9 mm/s to 18.3 mm/s by the temperature traces. NZPV determined by these two approaches agrees well with each other. Also, NZPV of double-layer YBCO tape is close to that of conventional single-layer superconducting tape.This work was supported in part by the EPSRC under Grant NMZF/064.This is the accepted manuscript. The final version is available from IEEE at http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6963291&sortType%3Dasc_p_Sequence%26filter%3DAND%28p_IS_Number%3A6353170%29%26rowsPerPage%3D50

The zebrafish xenograft platform-A novel tool for modeling KSHV-associated diseases

Kaposi\u27s sarcoma associated-herpesvirus (KSHV, also known as human herpesvirus-8) is a gammaherpesvirus that establishes life-long infection in human B lymphocytes. KSHV infection is typically asymptomatic, but immunosuppression can predispose KSHV-infected individuals to primary effusion lymphoma (PEL); a malignancy driven by aberrant proliferation of latently infected B lymphocytes, and supported by pro-inflammatory cytokines and angiogenic factors produced by cells that succumb to lytic viral replication. Here, we report the development of the firs

Sceptical Employees as CSR Ambassadors in Times of Financial Uncertainty

This chapter offers new insights into the understanding of internal (employee) perceptions of organizational corporate social responsibility (CSR) policies and strategies. This study explores the significance of employees’ involvement and scepticism upon CSR initiatives and focuses on the effects it may have upon word of mouth (WOM) and the development of employee–organisation relationships. Desk research introduces the research questions. Data for the research questions were gathered through a self-completion questionnaire distributed in a hardcopy form to the sample. An individual’s level of scepticism and involvement appears to affect the development of a positive effect on employees’ WOM. Involvement with the domain of the investment may be a central factor affecting relationship building within the organization, and upon generation of positive WOM. The chapter offers a conceptual framework to public relations (PR) and corporate communications practitioners, which may enrich their views and understanding of the use and value of CSR for communication strategies and practices. For-profit organisations are major institutions in today’s society. CSR is proffered as presenting advantages for (at macro level) society and (micro level) the organization and its employees. Concepts, such as involvement and scepticism, which have not been rigorously examined in PR and corporate communication literature, are addressed. By examining employee perceptions, managers and academic researchers gain insights into the acceptance, appreciation and effectiveness of CSR policies and activities upon the employee stakeholder group. This will affect current and future CSR communication strategies. The knowledge acquired from this chapter may be transferable outside the for-profit sector

Statistical estimation of trailing edge noise from finite wall-mounted airfoils

The 2016 Joint Conference of The Australian Acoustical Society and The Acoustical Society of New Zealand. Acoustics2016 - The Second Australasian Acoustical Societies ConferenceIt is important to be able to accurately model the flow and noise generated by finite wall-mounted airfoil flows because of the many engineering applications in which these flows occur. One method for predicting turbulent trailing edge noise is the Reynolds-averaged Navier-Stokes based statistical noise model (RSNM) of Doolan et al. (Proceedings of 20th International Congress on Acoustics, ICA 2010). The RSNM method has previously been used successfully on a range of two-dimensional geometry-flow cases. In this paper a new turbulent velocity cross-spectrum model and improved implementation are proposed to allow the RSNM method to be used to effectively and efficiently predict turbulent trailing edge noise from more complex three-dimensional cases. Reynolds-averaged Navier-Stokes (RANS) simulations of a series of wing-in-junction cases are used in combination with the developed acoustic model to predict the far-field noise and compared against experimental noise measurements.Jesse Coombs, Con Doolan, Anthony Zander, Danielle Moreau and Laura Brook