4,085 research outputs found
Electrophysiological responses to argument structure violations in healthy adults and individuals with nonfluent aphasia
Agrammatic individuals show impaired production of verbs with complex argument structure. Whether these participants show argument structure deficits during comprehension, however, is unclear. The present study investigated this issue by examining electrophysiological responses to argument structure violations in agrammatic individuals and healthy adults. Results showed that unlike control participants, who evinced a negative effect followed by a positive shift (N400-P600) in response to argument structure violations, individuals with agrammatic aphasia showed a P600 response only. This suggests impaired real time processing of the thematic requirements of verbs
Imaging resonant dissipation from individual atomic defects in graphene
Conversion of electric current into heat involves microscopic processes that
operate on nanometer length-scales and release minute amounts of power. While
central to our understanding of the electrical properties of materials,
individual mediators of energy dissipation have so far eluded direct
observation. Using scanning nano-thermometry with sub-micro K sensitivity we
visualize and control phonon emission from individual atomic defects in
graphene. The inferred electron-phonon 'cooling power spectrum' exhibits sharp
peaks when the Fermi level comes into resonance with electronic quasi-bound
states at such defects, a hitherto uncharted process. Rare in the bulk but
abundant at graphene's edges, switchable atomic-scale phonon emitters define
the dominant dissipation mechanism. Our work offers new insights for addressing
key materials challenges in modern electronics and engineering dissipation at
the nanoscale
Association between cognitive performance and cortical glucose metabolism in patients with mild Alzheimer's disease
Background: Neuronal and synaptic function in Alzheimer's disease (AD) is measured in vivo by glucose metabolism using positron emission tomography (PET). Objective: We hypothesized that neuronal activation as measured by PET is a more sensitive index of neuronal dysfunction than activity during rest. We investigated if the correlations between dementia severity as measured with the Mini Mental State Examination (MMSE) and glucose metabolism are an artifact of brain atrophy. Method: Glucose metabolism was measured using {[}F-18]fluorodeoxyglucose PET during rest and activation due to audiovisual stimulation in 13 mild to moderate AD patients (MMSE score >= 17). PET data were corrected for brain atrophy. Results: In the rest condition, glucose metabolism was correlated with the MMSE score primarily within the posterior cingulate and parietal lobes. For the activation condition, additional correlations were within the primary and association audiovisual areas. Most local maxima remained significant after correcting for brain atrophy. Conclusion: PET activity measured during audiovisual stimulation was more sensitive to functional alterations in glucose metabolism in AD patients compared to the resting PET. The association between glucose metabolism and MMSE score was not dependent on brain atrophy. Copyright (C) 2005 S. Karger AG, Basel
The construction of social housing pathways across Australia
This report examines the formal social housing pathways set out in policy and how these differ across jurisdictions. It uses a systems thinking approach to examine how actors, levers, feedback loops, incentives and disincentives influence formal social housing pathways. The discussion presents evidence from a comprehensive policy review, as well as data from interviews and a workshop with key stakeholders, including government representatives and community housing managers
Word-finding pauses in primary progressive aphasia (PPA): Effects of lexical category
Word-finding pauses are common in logopenic primary progressive aphasia (PPA-L). However, no previous research investigated the distribution of word-finding pauses in PPA or their specificity to PPA-L. We coded pauses preceding nouns and verbs in narrative speech samples from participants with PPA-L, agrammatic (PPA-G) and semantic PPA (PPA-S), and controls, hypothesizing that frequent word-finding pauses, if present, should match previously-observed lexical category deficits (noun deficits in PPA-L and PPA-S; verb deficits in PPA-G).The PPA-L group paused more frequently before nouns than verbs, whereas no other group exhibited lexical category effects, suggesting that frequent word-finding pauses are specific to PPA-L
Radial oscillations of relativistic stars
We present a new survey of the radial oscillation modes of neutron stars.
This study complements and corrects earlier studies of radial oscillations. We
present an extensive list of frequencies for the most common equations of state
and some more recent ones. In order to check the accuracy, we use two different
numerical schemes which yield the same results. The stimulation for this work
comes from the need of the groups that evolve the full nonlinear Einstein
equation to have reliable results from perturbation theory for comparison.Comment: 8 pages, 1 figure, 20 tables, accepted for publication in A&
Striatal dopamine D2 receptor binding of risperidone in schizophrenic patients as assessed by 123I-iodobenzamide SPECT: a comparative study with olanzapine
The aim of this investigation was to compare the degree of striatal dopamine-(D2) receptor blockade by two atypical antipsychotic drugs, risperidone and olanzapine. The percentage of D2 receptor occupancy during treatment was calculated by comparing the results of 123I-iodobenzamide SPECT with those from healthy control subjects. Twenty inpatients suffering from schizophrenia or schizoaffective psychosis according to DSM IV/ICD-10 criteria were treated with clinically recommended doses of risperidone and compared with 13 inpatients treated with up to 20 mg olanzapine. Neuroleptic dose and D2 receptor blockade correlated strongly for both risperidone (Pearson r = –0.86, p = 0.0001) and olanzapine (Pearson r = –0.77, p = 0.002). There was no significant difference between the D2 receptor occupancy of the two substances when given in the clinically recommended dose range (unpaired t-test, t= –0.112, p=0.911)
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