37 resultados para photocurrent spectrum
em Aston University Research Archive
Resumo:
We conducted a detailed study of a case of linguistic talent in the context of autism spectrum disorder, specifically Asperger syndrome. I.A. displays language strengths at the level of morphology and syntax. Yet, despite this grammar advantage, processing of figurative language and inferencing based on context presents a problem for him. The morphology advantage for I.A. is consistent with the weak central coherence (WCC) account of autism. From this account, the presence of a local processing bias is evident in the ways in which autistic individuals solve common problems, such as assessing similarities between objects and finding common patterns, and may therefore provide an advantage in some cognitive tasks compared to typical individuals. We extend the WCC account to language and provide evidence for a connection between the local processing bias and the acquisition of morphology and grammar.
Resumo:
We present an ESR study at excitation frequencies of 9.4 GHz and 222.4 GHz of powders and single crystals of a Prussian Blue analogue (PBA), RbMn[Fe(CN)6]*H2O in which Fe and Mn undergoes a charge transfer transition between 175 and 300 K. The ESR of PBA powders, also reported by Pregelj et al. (JMMM, 316, E680 (2007)) is assigned to cubic magnetic clusters of Mn2+ ions surrounding Fe(CN)6 vacancies. The clusters are well isolated from the bulk and are superparamagnetic below 50 K. In single crystals various defects with lower symmetry are also observed. Spin-lattice relaxation broadens the bulk ESR beyond observability. This strong spin relaxation is unexpected above the charge transfer transition and is attributed to a mixing of the Mn3+ - Fe2+ state into the prevalent Mn2+ - Fe3+ state.
Resumo:
Autism is a pervasive developmental disorder and Asperger’s syndrome is part of the spectrum of autism disorders. This thesis aims to: • Review and investigate current theories concerning visual function in individuals with Asperger’s syndrome and high functioning autism spectrum disorder and to translate the findings into clinical practice by developing a specific protocol for the eye examination of individuals of this population. • Investigate whether those with Asperger’s syndrome are more likely to suffer from Meares-Irlen syndrome and/or dyslexia. • Assess the integrity of the M-cell pathway in Asperger’s syndrome using perimetric tests available in optometric practice to investigate and also to describe the nature of any defects. • Evaluate eye movement strategies in Asperger’s whilst viewing both text and images. Also to evaluate the most appropriate methodology for investigating eye movements; namely optical digital eye tracking and electrophysiology methodologies. Findings of the investigations include • Eye examinations for individuals with Asperger’s syndrome should contain the same testing methods as for the general population, with special consideration for clear communication. • There is a depression of M-pathway visual field sensitivity in 57% (8/14) of people with Asperger’s syndrome, supporting previous evidence for an M-cell deficit in some individuals. • There is a raised prevalence of dyslexia in Asperger’s syndrome (26% of a sample of 31) but not necessarily of Meares-Irlen syndrome. • Gaze strategies are abnormal in Asperger’s syndrome, for both reading and viewing of images. With increased saccadic movement and decreased viewing of faces in comparison to background detail.
Resumo:
We propose a novel technique for optical liquid level sensing. The technique takes advantage of an optical spectrum spreading technique and directly measures liquid level with a digital format. The performance of the sensor does not suffer from changes of environmental variables and system variables. Due to its distinct measurement principle both high resolution and a large measurement range can be achieved simultaneously.
Resumo:
The channelled spectrum of an optical beam generated by a laser diode operated below threshold after traversing microscope glass plates is spectrally analysed using a grating and a CCD linear array. The experiment has the following goals: to display the resulting channelled spectrum, to familiarize students with an important topic in metrology and to illustrate some interesting topics from spectroscopy using a CCD array as a spectrometer.
Resumo:
We describe an experimental demonstration of a novel technique for liquid refractometry. A channeled spectrum is produced from an optical beam generated by a diode laser operating below threshold by intercepting half of the beam with a liquid cell. The spectrum is analyzed using a grating and a linear CCD array and provides information on the refractive index of the liquid. The experimental results show that accuracies of better than 0.3% in the index may be obtained with the present method.
Resumo:
A novel form of low coherence interferometric sensor is described. The channelled spectrum produced by illuminating a sensing interferometer with a broadband source is analysed directly using a CCD array. The system currently provides unambiguous measurement over a range of 1.5 mm with an accuracy of better than 6 µm.
Resumo:
Neuronal intermediate filament inclusion disease (NIFID), a rare form of frontotemporal lobar degeneration (FTLD), is characterized neuropathologically by focal atrophy of the frontal and temporal lobes, neuronal loss, gliosis, and neuronal cytoplasmic inclusions (NCI) containing epitopes of ubiquitin and neuronal intermediate filament proteins. Recently, the 'fused in sarcoma' (FUS) protein (encoded by the FUS gene) has been shown to be a component of the inclusions of familial amyotrophic lateral sclerosis with FUS mutation, NIFID, basophilic inclusion body disease, and atypical FTLD with ubiquitin-immunoreactive inclusions (aFTLD-U). To further characterize FUS proteinopathy in NIFID, and to determine whether the pathology revealed by FUS immunohistochemistry (IHC) is more extensive than a-internexin, we have undertaken a quantitative assessment of ten clinically and neuropathologically well-characterized cases using FUS IHC. The densities of NCI were greatest in the dentate gyrus (DG) and in sectors CA1/2 of the hippocampus. Anti-FUS antibodies also labeled glial inclusions (GI), neuronal intranuclear inclusions (NII), and dystrophic neurites (DN). Vacuolation was extensive across upper and lower cortical layers. Significantly greater densities of abnormally enlarged neurons and glial cell nuclei were present in the lower compared with the upper cortical laminae. FUS IHC revealed significantly greater numbers of NCI in all brain regions especially the DG. Our data suggest: (1) significant densities of FUS-immunoreactive NCI in NIFID especially in the DG and CA1/2; (2) infrequent FUS-immunoreactive GI, NII, and DN; (3) widely distributed vacuolation across the cortex, and (4) significantly more NCI revealed by FUS than a-internexin IHC.
Resumo:
Existing wireless systems are normally regulated by a fixed spectrum assignment strategy. This policy leads to an undesirable situation that some systems may only use the allocated spectrum to a limited extent while others have very serious spectrum insufficiency situation. Dynamic Spectrum Access (DSA) is emerging as a promising technology to address this issue such that the unused licensed spectrum can be opportunistically accessed by the unlicensed users. To enable DSA, the unlicensed user shall have the capability of detecting the unoccupied spectrum, controlling its spectrum access in an adaptive manner, and coexisting with other unlicensed users automatically. In this article, we propose a radio system Transmission Opportunity-based spectrum access control protocol with the aim to improve spectrum access fairness and ensure safe coexistence of multiple heterogeneous unlicensed radio systems. In the scheme, multiple radio systems will coexist and dynamically use available free spectrum without interfering with licensed users. Simulation is carried out to evaluate the performance of the proposed scheme with respect to spectrum utilisation, fairness and scalability. Comparing with the existed studies, our strategy is able to achieve higher scalability and controllability without degrading spectrum utilisation and fairness performance.
Resumo:
Bipolar disorder (BP) is among the top ten most disabling illnesses worldwide. This review includes findings from recent studies employing functional neuroimaging to examine functional abnormalities in neural systems underlying core domains of the psychopathology in BP: emotion processing, emotion regulation and executive control, and common comorbid features of BP, that are relevant to the wide spectrum of BP rather than focused on the more traditional BPI subtype, and that may facilitate future identification of diagnostically-relevant biomarkers of the disorder. In addition, an emerging number of studies are reviewed that demonstrate the use of neuroimaging to elucidate biomarkers whose identification may help to (1) identify at-risk individuals who will subsequently develop the illness to facilitate early intervention, (2) identify targets for treatment and markers of treatment response. The use of newer neuroimaging techniques and potential confounds of psychotropic medication upon neuroimaging findings in BP are also examined. These approaches will help to improve diagnosis and the mental well-being of all individuals with BP.
Resumo:
With the reformation of spectrum policy and the development of cognitive radio, secondary users will be allowed to access spectrums licensed to primary users. Spectrum auctions can facilitate this secondary spectrum access in a market-driven way. To design an efficient auction framework, we first study the supply and demand pressures and the competitive equilibrium of the secondary spectrum market, considering the spectrum reusability. In well-designed auctions, competition among participants should lead to the competitive equilibrium according to the traditional economic point of view. Then, a discriminatory price spectrum double auction framework is proposed for this market. In this framework, rational participants compete with each other by using bidding prices, and their profits are guaranteed to be non-negative. A near-optimal heuristic algorithm is also proposed to solve the auction clearing problem of the proposed framework efficiently. Experimental results verify the efficiency of the proposed auction clearing algorithm and demonstrate that competition among secondary users and primary users can lead to the competitive equilibrium during auction iterations using the proposed auction framework. Copyright © 2011 John Wiley & Sons, Ltd.
Resumo:
A novel form of low coherence interferometric sensor is described. The channelled spectrum produced by illuminating a sensing interferometer with a broadband source is analysed directly using a CCD array. The system currently provides unambiguous measurement over a range of 1.5 mm with an accuracy of better than 6 µm.
Resumo:
The channelled spectrum of an optical beam generated by a laser diode operated below threshold after traversing microscope glass plates is spectrally analysed using a grating and a CCD linear array. The experiment has the following goals: to display the resulting channelled spectrum, to familiarize students with an important topic in metrology and to illustrate some interesting topics from spectroscopy using a CCD array as a spectrometer.
Resumo:
Sensory processing is a crucial underpinning of the development of social cognition, a function which is compromised in variable degree in patients with pervasive developmental disorders (PDD). In this manuscript, we review some of the most recent and relevant contributions, which have looked at auditory sensory processing derangement in PDD. The variability in the clinical characteristics of the samples studied so far, in terms of severity of the associated cognitive deficits and associated limited compliance, underlying aetiology and demographic features makes a univocal interpretation arduous. We hypothesise that, in patients with severe mental deficits, the presence of impaired auditory sensory memory as expressed by the mismatch negativity could be a non-specific indicator of more diffuse cortical deficits rather than causally related to the clinical symptomatology. More consistent findings seem to emerge from studies on less severely impaired patients, in whom increased pitch perception has been interpreted as an indicator of increased local processing, probably as compensatory mechanism for the lack of global processing (central coherence). This latter hypothesis seems extremely attractive and future trials in larger cohorts of patients, possibly standardising the characteristics of the stimuli are a much-needed development. Finally, specificity of the role of the auditory derangement as opposed to other sensory channels needs to be assessed more systematically using multimodal stimuli in the same patient group. (c) 2006 Elsevier B.V. All rights reserved.
Resumo:
Much of the research on visual hallucinations (VHs) has been conducted in the context of eye disease and neurodegenerative conditions, but little is known about these phenomena in psychiatric and nonclinical populations. The purpose of this article is to bring together current knowledge regarding VHs in the psychosis phenotype and contrast this data with the literature drawn from neurodegenerative disorders and eye disease. The evidence challenges the traditional views that VHs are atypical or uncommon in psychosis. The weighted mean for VHs is 27% in schizophrenia, 15% in affective psychosis, and 7.3% in the general community. VHs are linked to a more severe psychopathological profile and less favorable outcome in psychosis and neurodegenerative conditions. VHs typically co-occur with auditory hallucinations, suggesting a common etiological cause. VHs in psychosis are also remarkably complex, negative in content, and are interpreted to have personal relevance. The cognitive mechanisms of VHs in psychosis have rarely been investigated, but existing studies point to source-monitoring deficits and distortions in top-down mechanisms, although evidence for visual processing deficits, which feature strongly in the organic literature, is lacking. Brain imaging studies point to the activation of visual cortex during hallucinations on a background of structural and connectivity changes within wider brain networks. The relationship between VHs in psychosis, eye disease, and neurodegeneration remains unclear, although the pattern of similarities and differences described in this review suggests that comparative studies may have potentially important clinical and theoretical implications. © 2014 The Author.