Plasticity in bilateral superior temporal cortex: Effects of deafness and cochlear implantation on auditory and visual speech processing

While many individuals can benefit substantially from cochlear implantation, the ability to perceive and understand auditory speech with a cochlear implant (CI) remains highly variable amongst adult recipients. Importantly, auditory performance with a CI cannot be reliably predicted based solely on routinely obtained information regarding clinical characteristics of the CI candidate. This review argues that central factors, notably cortical function and plasticity, should also be considered as important contributors to the observed individual variability in CI outcome. Superior temporal cortex (STC), including auditory association areas, plays a crucial role in the processing of auditory and visual speech information. The current review considers evidence of cortical plasticity within bilateral STC, and how these effects may explain variability in CI outcome. Furthermore, evidence of audio-visual interactions in temporal and occipital cortices is examined, and relation to CI outcome is discussed. To date, longitudinal examination of changes in cortical function and plasticity over the period of rehabilitation with a CI has been restricted by methodological challenges. The application of functional near-infrared spectroscopy (fNIRS) in studying cortical function in CI users is becoming increasingly recognised as a potential solution to these problems. Here we suggest that fNIRS offers a powerful neuroimaging tool to elucidate the relationship between audio-visual interactions, cortical plasticity during deafness and following cochlear implantation, and individual variability in auditory performance with a CI

On the combination of high-pressure and low-pressure exhaust gas recirculation loops for improved fuel economy and reduced emissions in high-speed direct-injection engines

In this paper, an experimental study of the combination of low-pressure and high-pressure exhaust gas recirculation architectures has been carried out. In the first part of the paper, the effects of both high-pressure and low-pressure exhaust gas recirculation architectures on engine behaviour and performance are analysed by means of a series of steady tests. In the second part, the effects of the combination of both architectures are addressed. The results show that the low-pressure configuration improves high-pressure exhaust gas recirculation results in brake-specific fuel consumption, nitrogen oxides and exhaust gas opacity; nevertheless, hydrocarbon emissions are increased, especially during the engine warm up. In addition, the exhaust gas recirculation rate achieved with low-pressure systems is limited by the pressure difference between diesel particulate matter outlet and compressor inlet; therefore, the high-pressure system can be used to achieve the required exhaust gas recirculation levels without increasing pumping losses. In this sense, the combination of both exhaust gas recirculation layouts offers significant advantages to reduce emissions and fuel consumption to meet future emission requirements.This work was supported by the Ministry of Science and Innovation (Spanish Government) [grant number IPT-370000-2010-022].Desantes Fernández, JM.; Luján, JM.; Plá Moreno, B.; Soler Muniesa, JA. (2013). On the combination of high-pressure and low-pressure exhaust gas recirculation loops for improved fuel economy and reduced emissions in high-speed direct-injection engines. International Journal of Engine Research. 14(1):3-11. https://doi.org/10.1177/1468087412437623S311141Taylor, A. M. K. P. (2008). Science review of internal combustion engines. Energy Policy, 36(12), 4657-4667. doi:10.1016/j.enpol.2008.09.001Lü, X.-C., Chen, W., & Huang, Z. (2005). A fundamental study on the control of the HCCI combustion and emissions by fuel design concept combined with controllable EGR. Part 2. Effect of operating conditions and EGR on HCCI combustion. Fuel, 84(9), 1084-1092. doi:10.1016/j.fuel.2004.12.015Nakano, M., Mandokoro, Y., Kubo, S., & Yamazaki, S. (2000). Effects of exhaust gas recirculation in homogeneous charge compression ignition engines. International Journal of Engine Research, 1(3), 269-279. doi:10.1243/1468087001545173Zheng, M., Reader, G. T., & Hawley, J. G. (2004). Diesel engine exhaust gas recirculation––a review on advanced and novel concepts. Energy Conversion and Management, 45(6), 883-900. doi:10.1016/s0196-8904(03)00194-8Hountalas, D. T., Mavropoulos, G. C., & Binder, K. B. (2008). Effect of exhaust gas recirculation (EGR) temperature for various EGR rates on heavy duty DI diesel engine performance and emissions. Energy, 33(2), 272-283. doi:10.1016/j.energy.2007.07.002Luján, J. M., Galindo, J., Serrano, J. R., & Pla, B. (2008). A methodology to identify the intake charge cylinder-to-cylinder distribution in turbocharged direct injection Diesel engines. Measurement Science and Technology, 19(6), 065401. doi:10.1088/0957-0233/19/6/065401Ladommatos, N., Abdelhalim, S., & Zhao, H. (2000). The effects of exhaust gas recirculation on diesel combustion and emissions. International Journal of Engine Research, 1(1), 107-126. doi:10.1243/1468087001545290Maiboom, A., Tauzia, X., & Hétet, J.-F. (2008). Influence of high rates of supplemental cooled EGR on NOxand PM emissions of an automotive HSDI diesel engine using an LP EGR loop. International Journal of Energy Research, 32(15), 1383-1398. doi:10.1002/er.1455Gautier, P., Albrecht, A., Chasse, A., Moulin, P., Pagot, A., Fontvieille, L., & Issartel, D. (2009). A Simulation Study of the Impact of LP EGR on a Two-Stage Turbocharged Diesel Engine. Oil & Gas Science and Technology - Revue de l’IFP, 64(3), 361-379. doi:10.2516/ogst/2009019Torregrosa, A. J., Olmeda, P., Martín, J., & Degraeuwe, B. (2006). Experiments on the influence of inlet charge and coolant temperature on performance and emissions of a DI Diesel engine. Experimental Thermal and Fluid Science, 30(7), 633-641. doi:10.1016/j.expthermflusci.2006.01.00

Mirizzi syndrome associated with hepatic artery pseudoaneurysm: a case report.

INTRODUCTION: This is the first case report of Mirizzi syndrome associated with hepatic artery pseudoaneurysm. CASE PRESENTATION: A 54-year-old man presented with painful obstructive jaundice and weight loss. Computed tomography showed a hilar mass in the liver. Following an episode of haemobilia, angiography demonstrated a pseudoaneurysm of a branch of the right hepatic artery that was embolised. At surgery, a gallstone causing Mirizzi type II syndrome was found to be responsible for the biliary obstruction and a necrotic inflammatory mass and haematoma were found to be extending into the liver. The mass was debrided and drained, the obstructing stones removed and the bile duct drained with a t-tube. The patient made a full recovery. CONCLUSION: This case highlights another situation where there may be difficulty in differentiating Mirizzi syndrome from biliary tract cancer.Published versio

The structural invisibility of outsiders: the role of migrant labour in the meat-processing industry

This article examines the role of migrant workers in meat-processing factories in the UK. Drawing on materials from mixed methods research in a number of case study towns across Wales, we explore the structural and spatial processes that position migrant workers as outsiders. While state policy and immigration controls are often presented as a way of protecting migrant workers from work-based exploitation and ensuring jobs for British workers, our research highlights that the situation ‘on the ground’ is more complex. We argue that ‘self-exploitation’ among the migrant workforce is linked to the strategies of employers and the organisation of work, and that hyper-flexible work patterns have reinforced the spatial and social invisibilities of migrant workers in this sector. While this creates problems for migrant workers, we conclude that it is beneficial to supermarkets looking to supply consumers with the regular supply of cheap food to which they have become accustomed

Quantum dimer models and exotic orders

We discuss how quantum dimer models may be used to provide "proofs of principle" for the existence of exotic magnetic phases in quantum spin systems.Comment: 12 pages, 6 figures. Contributed talk at the PITP-Les Houches Summer School on "Quantum Magnetism", June 200

Visual population receptive fields in people with schizophrenia have reduced inhibitory surrounds

People with schizophrenia (SZ) experience abnormal visual perception on a range of visual tasks, which have been linked to abnormal synaptic transmission and an imbalance between cortical excitation and inhibition. However differences in the underlying architecture of visual cortex neurons, which might explain these visual anomalies, have yet to be reported in vivo. Here, we probe the neural basis of these deficits by using functional MRI (fMRI) and population receptive field (pRF) mapping to infer properties of visually responsive neurons in people with SZ. We employed a Difference-of-Gaussian (DoG) model to capture the centre-surround configuration of the pRF, providing critical information about the spatial scale of the pRFs inhibitory surround. Our analysis reveals that SZ is associated with reduced pRF size in early retinotopic visual cortex as well as a reduction in size and depth of the inhibitory surround in V1, V2 and V4. We consider how reduced inhibition might explain the diverse range of visual deficits reported in SZ. SIGNIFICANCE STATEMENT: People with schizophrenia (SZ) experience abnormal perception on a range of visual tasks, which has been linked to abnormal synaptic transmission and an imbalance between cortical excitation/inhibition. However associated differences in the underlying architecture of visual cortex neurons have yet to be reported in vivo. We used fMRI and population receptive field (pRF) mapping to demonstrate that the fine-grained functional architecture of visual cortex in people with SZ differs from unaffected controls. SZ is associated with reduced pRF size in early retinotopic visual cortex, largely due to reduced inhibitory surrounds. An imbalance between cortical excitation and inhibition could drive such a change in the centre-surround pRF configuration, and ultimately explain the range of visual deficits experienced in SZ

Statistical Signatures of Photon Localization

The realization that electron localization in disordered systems (Anderson localization) is ultimately a wave phenomenon has led to the suggestion that photons could be similarly localized by disorder. This conjecture attracted wide interest because the differences between photons and electrons - in their interactions, spin statistics, and methods of injection and detection - may open a new realm of optical and microwave phenomena, and allow a detailed study of the Anderson localization transition undisturbed by the Coulomb interaction. To date, claims of three-dimensional photon localization have been based on observations of the exponential decay of the electromagnetic wave as it propagates through the disordered medium. But these reports have come under close scrutiny because of the possibility that the decay observed may be due to residual absorption, and because absorption itself may suppress localization. Here we show that the extent of photon localization can be determined by a different approach - measurement of the relative size of fluctuations of certain transmission quantities. The variance of relative fluctuations accurately reflects the extent of localization, even in the presence of absorption. Using this approach, we demonstrate photon localization in both weakly and strongly scattering quasi-one-dimensional dielectric samples and in periodic metallic wire meshes containing metallic scatterers, while ruling it out in three-dimensional mixtures of aluminum spheres.Comment: 5 pages, including 4 figure