5,606 research outputs found

    The right information may matter more than frequency-place alignment: Simulations of frequency-aligned and upward shifting cochlear implant processors for a shallow electrode array insertion

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    Objective: It has been claimed that speech recognition with a cochlear implant is dependent on the correct frequency alignment of analysis bands in the speech processor with characteristic frequencies (CFs) at electrode locations. However, the use of filters aligned in frequency to a relatively basal electrode array position leads to significant loss of lower frequency speech information. This study uses an acoustic simulation to compare two approaches to the matching of speech processor filters to an electrode array having a relatively shallow depth within the typical range, such that the most apical element is at a CF of 1851 Hz. Two noise-excited vocoder speech processors are compared, one with CF-matched filters, and one with filters matched to CFs at basilar membrane locations 6 mm more apical than electrode locations.Design: An extended crossover training design examined pre- and post-training performance in the identification of vowels and words in sentences for both processors. Subjects received about 3 hours of training with each processor in turn.Results: Training improved performance with both processors, but training effects were greater for the shifted processor. For a male talker, the shifted processor led to higher post-training scores than the frequency-aligned processor with both vowels and sentences. For a female talker, post-training vowel scores did not differ significantly between processors, whereas sentence scores were higher with the frequency-aligned processor.Conclusions: Even for a shallow electrode insertion, we conclude that a speech processor should represent information from important frequency regions below 1 kHz and that the possible cost of frequency misalignment can be significantly reduced with listening experience

    Translating the complexities of flood risk science using KEEPER - a knowledge exchange exploratory tool for professionals in emergency response

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    Within flood risk management (FRM) decision making, there is a growing interest in participatory approaches to engage and integrate stakeholder expertise. Decision support tools are becoming common features in the FRM ‘toolkit’, yet there is a limited application of participatory methodologies in the construction of such tools. This paper reports on completed FRMRC research (Flood Risk Management Research Consortium, UK http://www.floodrisk.org.uk/) and the construction of a geographic information system-based flood risk assessment tool, KEEPER – a Knowledge Exchange Exploratory tool for Professionals in Emergency Response. An iterative methodology was used to engage emergency professionals throughout the research process, allowing a mixing of scientific and professional expertise in the co-production of KEEPER. KEEPER was both instrumental in facilitating participation and knowledge exchange, and informing recommendations for future tools in practice. This paper argues that participation is both essential for supporting pragmatic flood research and as a means of enhancing communication across traditionally divided communities

    Inferior frontal gyrus activation predicts individual differences in perceptual learning of cochlear-implant simulations

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    This study investigated the neural plasticity associated with perceptual learning of a cochlear implant (CI) simulation. Normal-hearing listeners were trained with vocoded and spectrally-shifted speech simulating a CI while cortical responses were measured with fMRI. A condition in which the vocoded speech was spectrally inverted provided a control for learnability and adaptation. Behavioral measures showed considerable individual variability both in the ability to learn to understand the degraded speech, and in phonological working memory capacity. Neurally, left-lateralized regions in superior temporal sulcus and inferior frontal gyrus (IFG) were sensitive to the learnability of the simulations, but only the activity in prefrontal cortex correlated with inter-individual variation in intelligibility scores and phonological working memory. A region in left angular gyrus (AG) showed an activation pattern that reflected learning over the course of the experiment, and co-variation of activity in AG and IFG was modulated by the learnability of the stimuli. These results suggest that variation in listeners' ability to adjust to vocoded and spectrally-shifted speech is partly reflected in differences in the recruitment of higher-level language processes in prefrontal cortex, and that this variability may further depend on functional links between the left inferior frontal gyrus and angular gyrus. Differences in the engagement of left inferior prefrontal cortex, and its co-variation with posterior parietal areas, may thus underlie some of the variation in speech perception skills that have been observed in clinical populations of CI users

    Stellar spectroscopy: Fermions and holographic Lifshitz criticality

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    Electron stars are fluids of charged fermions in Anti-de Sitter spacetime. They are candidate holographic duals for gauge theories at finite charge density and exhibit emergent Lifshitz scaling at low energies. This paper computes in detail the field theory Green's function G^R(w,k) of the gauge-invariant fermionic operators making up the star. The Green's function contains a large number of closely spaced Fermi surfaces, the volumes of which add up to the total charge density in accordance with the Luttinger count. Excitations of the Fermi surfaces are long lived for w <~ k^z. Beyond w ~ k^z the fermionic quasiparticles dissipate strongly into the critical Lifshitz sector. Fermions near this critical dispersion relation give interesting contributions to the optical conductivity.Comment: 38 pages + appendices. 9 figure

    The emerging landscape of reimbursement of regenerative medicine products in the UK: publications, policies and politics

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    Aims This paper aims to map the trends and analyse key institutional dynamics that are constituting the policies for reimbursement of Regenerative Medicine (RM), especially in the UK. Materials & Methods Two quantitative publications studies using Google Scholar and a qualitative study based on a larger study of 43 semi- structured interviews. Results Reimbursement has been a growing topic of publications specific to RM and independent from orphan drugs. Risk- sharing schemes receive attention amongst others for dealing with RM reimbursement. Trade organisations have been especially involved on RM reimbursement issues and have proposed solutions. Conclusion The policy and institutional landscape of reimbursement studies in RM is a highly variegated and conflictual one and in its infancy

    Interplay between CCR7 and Notch1 axes promotes stemness in MMTV-PyMT mammary cancer cells

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    Background: Breast cancer is the major cause of cancer-related mortality in women. It is thought that quiescent stem-like cells within solid tumors are responsible for cancer maintenance, progression and eventual metastasis. We recently reported that the chemokine receptor CCR7, a multi-functional regulator of breast cancer, maintains the stem-like cell population. Methods: This study used a combination of molecular and cellular assays on primary mammary tumor cells from the MMTV-PyMT transgenic mouse with or without CCR7 to examine the signaling crosstalk between CCR7 and Notch pathways. Results: We show for the first time that CCR7 functionally intersects with the Notch signaling pathway to regulate mammary cancer stem-like cells. In this cell subpopulation, CCR7 stimulation activated the Notch signaling pathway, and deletion of CCR7 significantly reduced the levels of activated cleaved Notch1. Moreover, blocking Notch activity prevented specific ligand-induced signaling of CCR7 and augmentation of mammary cancer stem-like cell function. Conclusion: Crosstalk between CCR7 and Notch1 promotes stemness in mammary cancer cells and may ultimately potentiate mammary tumor progression. Therefore, dual targeting of both the CCR7 receptor and Notch1 signaling axes may be a potential therapeutic avenue to specifically inhibit the functions of breast cancer stem cells.Sarah T. Boyle, Krystyna A. Gieniec, Carly E. Gregor, Jessica W. Faulkner, Shaun R. McColl and Marina Kochetkov

    Persistent Current of Free Electrons in the Plane

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    Predictions of Akkermans et al. are essentially changed when the Krein spectral displacement operator is regularized by means of zeta function. Instead of piecewise constant persistent current of free electrons on the plane one has a current which varies linearly with the flux and is antisymmetric with regard to all time preserving values of α\alpha including 1/21/2. Different self-adjoint extensions of the problem and role of the resonance are discussed.Comment: (Comment on "Relation between Persistent Currents and the Scattering Matrix", Phys. Rev. Lett. {\bf 66}, 76 (1991)) plain latex, 4pp., IPNO/TH 94-2

    Virtual-crystal approximation that works: Locating a composition phase boundary in Pb(Zr_{1-x}Ti_3)O_3

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    We present a new method for modeling disordered solid solutions, based on the virtual crystal approximation (VCA). The VCA is a tractable way of studying configurationally disordered systems; traditionally, the potentials which represent atoms of two or more elements are averaged into a composite atomic potential. We have overcome significant shortcomings of the standard VCA by developing a potential which yields averaged atomic properties. We perform the VCA on a ferroelectric oxide, determining the energy differences between the high-temperature rhombohedral, low-temperature rhombohedral and tetragonal phases of Pb(Zr_{1-x}Ti_x)O_3 at x=0.5 and comparing these results to superlattice calculations and experiment. We then use our new method to determine the preferred structural phase at x=0.4. We find that the low-temperature rhombohedral phase becomes the ground state at x=0.4, in agreement with experimental findings.Comment: 5 pages, no figure

    The vocal construction of self : Icelandic men and singing in everyday life.

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    Musical identity and music in everyday life have both enjoyed increasing popularity in recent research and discourse. The present study is related to both these themes and investigates the nature and function of singing in men's everyday lives. Using Interpretative Phenomenological Analysis (IPA), the study looks specifically at vocal lives constructed in interviews with 13 men from northeast Iceland. Additionally these men and sixteen others, who sing in the same choir, kept one-week vocal diaries in order to facilitate the sampling of their everyday vocal experience. Interpretations of this data are situated contextually by the critical use of historical, anthropological, sociological, and ethnographical data. Emerging themes suggest that these men see singing as a central concept of Self. Furthermore, these themes appear to correspond closely to the psychological theory proposed by Robert Weber in his recent revision of William James's seminal, triadic model of Self. Men in the study locate Self in singing: their vocal behaviour appears to be an important technology of Self; that is a forming agent and defining concept in elements of physical, social and spiritual Self. Findings illustrate singing's agency in the changing Self and in the maintaining of core and unitary Selves. They exemplify ways in which vocal behaviour configures personal and social life and how personal and social identities can be vocally constructed, performed, and celebrated. Additionally, men's vocal behaviour and men's narratives about them, construct complex and times contradictory masculine identities. The study argues for the importance of phenomenological paradigms and in particular, for a music psychology of individuality which attempts to build theory from individual case studies towards the nomethetic. These research frameworks are shown here as being able to provide unique perspectives on the nature of musical and vocal function
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