Modality effects and the development of the word length effect in children.

Two experiments investigated the development of the word length effect in children aged 4 to 10 years, comparing auditory and visual stimuli. The question addressed was whether word length effects emerged earlier with auditory presentation or visual presentation, or whether they emerged at the same age regardless of presentation modality. Results provided evidence that word length effects emerge earlier with visual than auditory presentation. The implication of our results is that with visual presentation, 4-year-olds engage in some form of verbalization strategy that involves obtaining phonological representations of picture names and mapping them on to articulatory output plans. This strategy is clearly verbal in nature, but is not necessarily characterised as cumulative verbal rehearsal.

Neuropsychological, neurological and functional outcome following pallidotomy for Parkinson's disease. A consecutive series of eight simultaneous bilateral and twelve unilateral procedures.

Intellectual, psychological and functional outcomes were evaluated in a consecutive series of 20 Parkinsonian patients who had unilateral (UPVP) or simultaneous bilateral posteroventral pallidotomy (BPVP) using Image Fusion and Stereoplan (Radionics Inc., Boston, Mass., USA) with stimulation for lesion localization. Comprehensive baseline and 3-month postoperative neuropsychological and neurological assessment protocols were administered together with questionnaire measures of functional disability, quality of life and psychological symptomatology. Changes in patients' clinical presentation and scores on psychometric tests, questionnaires and observational rating scales were then examined. We observed no new neuropsychiatric sequelae directly related to pallidotomy. Cognitive sequelae were restricted to selective reductions in categorical verbal fluency following UPVP (P < 0.001) and BPVP (P < 0.01) and a reduction in phonemic verbal fluency following BPVP (P < 0.01); these changes were not reported subjectively. A fall in diadochokinetic rates (P < 0.01) and some subjective reports of a worsening in pre-existing dysarthria, hypophonia and hypersalivation/drooling following BPVP also suggested changes in speech motor apparatus; however, these changes did not have significant functional consequences. There was one case of more generalized cognitive impairment following BPVP. We also observed significant symptomatic improvement on neurological rating scales; following UPVP, Total Unified Parkinson's Disease Rating Scale (UPDRS) scores improved by 27% (P < 0.01) and following BPVP the improvement was 53% (P < 0.05). Patients' perceptions of reduced postoperative functional disability and improvements in 'quality of life' also achieved statistical significance on a number of both physical and psychosocial questionnaire subscales.

Influence of the length and position of the collision cell on the resolving power attainable from collisionally activated processes in sector instruments.

The energy resolution in a high resolution tandem mass spectrometer was investigated in terms of the length and position of the central collision cell. Both these parameters have to be chosen carefully to eliminate collisional broadening phenomena that can severely limit the energy resolution in such instruments. A theory that describes collisional broadening, to first order, has been derived that accounts for the observed phenomena. It was found experimentally that collisional broadening can be reduced to less than 0.001 eV per kiloelectronvolt collision energy. Experimental data confirmed that only the size of the resolving slits and thermal broadening, due to the target gas, limited the ultimate energy resolution available.

Working memory span and phonological awareness tasks as predictors of early reading ability.

Relationships between complex memory span, simple memory span, phonological awareness tasks, and beginning reading were investigated. Seven-year-olds were administered two complex span tasks, two simple span tasks, and four phonological awareness tasks. Relationships between the tasks were assessed, as well as their predictive importance with regard to reading accuracy, reading comprehension, and arithmetic. Correlations revealed that three of the four phonological awareness tasks were highly correlated with one another and with both of the complex span tasks. Regression analyses showed that the phonological awareness and reading-related complex span scores accounted for unique and shared portions of the variance in all three cognitive abilities, while the arithmetic-related complex span scores only made a significant unique contribution to the variance in arithmetic. Finally, simple memory span scores only explained significant portions of the variance in any of the cognitive abilities when entered first into the regression equations. The results suggested that phonological awareness and complex span tasks make a shared and a unique contribution to the variance in all three cognitive abilities, questioning Daneman and Carpenter's (1980, 1983) domain-specific hypothesis.

Immunohistological diagnosis of primary brain lymphoma using monoclonal antibodies: confirmation of B-cell origin.

The antigenic characteristics of 20 primary cerebral lymphomas have been defined by their reactivity with a panel of monoclonal antibodies recognizing differentiation antigens of lymphocytes and other cell types. In 7 out of 20 cases (35%), immunohistological results were diagnostically crucial and this approach appeared almost to double the detection rate of brain lymphomas over a 10-year period. All 20 tumours were confirmed as B-cell neoplasms by the use of a monoclonal antibody (B-1) specific for B-lymphocytes, rather than by the demonstration of immunoglobulin production. Further immunophenotyping with antibody FMC7 indicated that the neoplastic B-cells had been 'arrested' at a relatively mature stage of differentiation. The importance of monoclonal antibody markers in the accurate diagnosis and characterization of primary cerebral lymphomas has now been established.