87 research outputs found

    Spatial memory deficits in patients after unilateral selective amygdalohippocampectomy

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    Contains fulltext : 64568.pdf (publisher's version ) (Open Access)The present study investigated the differential involvement of the right and left hippocampus in various forms of spatial memory: spatial search, positional memory versus object-location binding, and coordinate versus categorical processing. Twenty-five epilepsy patients with selective amygdalohippocampectomy were examined using a sensitive computer paradigm to measure these spatial memory aspects. The patients' performance was compared to a group of thirty healthy controls. The results show that the left amygdalohippocampectomy group performed poorly on the ability to bind together object information to coordinate spatial locations. In turn, the right amygdalohippocampectomy group was impaired in coordinate positional memory. Both patient groups were unimpaired on the spatial search task. These findings are discussed focusing on the "binding device" hypothesis in combination with the cognitive map theory.6 p

    Intelligence moderates the benefits of strategy instructions on memory performance: An adult-lifespan examination

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    Contains fulltext : 160798.pdf (publisher's version ) (Open Access)Whether older adults can compensate for their associative memory deficit by using memory strategies efficiently might depend on their general cognitive abilities. This study examined the moderating role of an IQ estimate on the beneficial effects of strategy instructions. A total of 142 participants (aged 18-85 years) received either intentional learning or strategy ("sentence generation") instructions during encoding of word pairs. Whereas young adults with a lower IQ benefited from strategy instructions, those with a higher IQ did not, presumably because they already use strategies spontaneously. Older adults showed the opposite effect: following strategy instructions, older adults with a higher IQ showed a strong increase in memory performance (approximately achieving the level of younger adults), whereas older adults with a lower IQ did not, suggesting that they have difficulties implementing the provided strategies. These results highlight the importance of the role of IQ in compensating for the aging-related memory decline.17 p

    Atoomlaagdepositie voor het verbeteren van het rendement van silicium zonnecellen

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    Toepassing van Al2O3 aangebracht met atoomlaagdepositie leidt tot uitmuntende oppervlaktepassivatie van c-Si. Zo verbeterde het rendement van een n-type zonnecel met 1% absoluut na toepassing van een ultradun Al2O3 laagje op de p-type emitter

    How does additional diagnostic testing influence the initial diagnosis in patients with cognitive complaints in a memory clinic setting?

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    Contains fulltext : 150589.pdf (publisher's version ) (Open Access)BACKGROUND: patients suspected of dementia frequently undergo additional diagnostic testing (e.g. brain imaging or neuropsychological assessment) after standard clinical assessment at a memory clinic. This study investigates the use of additional testing in an academic outpatient memory clinic and how it influences the initial diagnosis. METHODS: the initial diagnosis after standard clinical assessment (history, laboratory tests, cognitive screening and physical and neurological examination) and the final diagnosis after additional testing of 752 memory clinic patients were collected. We specifically registered if, and what type of, additional testing was requested. RESULTS: additional testing was performed in 518 patients (69%), 67% of whom underwent magnetic resonance imaging, 45% had neuropsychological assessment, 14% had cerebrospinal fluid analysis and 49% had (combinations of) other tests. This led to a modification of the initial diagnosis in 17% of the patients. The frequency of change was highest in patients with an initial non-Alzheimer's disease (AD) dementia diagnosis (54%, compared with 11 and 14% in patients with AD and 'no dementia'; P < 0.01). Finally, after additional testing 44% was diagnosed with AD, 9% with non-AD dementia and 47% with 'no dementia'. CONCLUSION: additional testing should especially be considered in non-AD patients. In the large group of patients with an initial AD or 'no dementia' diagnosis, additional tests have little diagnostic impact and may perhaps be used with more restraint.6 p

    Transfer and maintenance effects of online working-memory training in normal ageing and mild cognitive impairment

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    Item does not contain fulltextWorking memory (WM) is one of the cognitive functions that is susceptible to ageing-related decline. Interventions that are able to improve WM functioning at older age are thus highly relevant. In this pilot study, we explored the transfer effects of core WM training on the WM domain and other cognitive domains in 23 healthy older adults and 18 patients with amnestic mild cognitive impairment (MCI). Performance on neuropsychological tests was assessed before and after completion of the online five-week adaptive WM training, and after a three-month follow-up period. After training, both groups improved on the Digit Span and Spatial Span, gains that were maintained at follow-up. At an individual level, a limited number of participants showed reliable training gain. Healthy older adults, and to a lesser extent MCI patients, additionally improved on figural fluency at group level, but not at individual level. Results furthermore showed that global brain atrophy and hippocampal atrophy, as assessed by MRI, may negatively affect training outcome. Our study examined core WM training, showing gains on trained and untrained tasks within the WM domain, but no broad generalisation to other cognitive domains. More research is needed to evaluate the clinical relevance of these findings and to identify participant characteristics that are predictive of training gain.27 p

    Surface loss in ozone-based atomic layer deposition processes

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    The recombinative surface loss of O3 was investigated and its effects on the initial growth, film uniformity, and film conformality in atomic layer deposition (ALD) processes were illustrated. To determine O3 recombination probabilities over a wide range, a method was developed using high aspect ratio capillaries at the inlet to a mass spectrometer. Using this method, we measured O3 recombination probabilities ranging from 10-3 depending on the composition and temperature of the capillary surface. We utilized these measurements to understand dramatic variations in O3 loss observed during the initial growth of O3-based ALD Pt on Al2O3 and vice versa. Next, we studied the uniformity of O3-based ALD using ZnO ALD as a model system. Changes in the spatial uniformity of the ALD ZnO films and the O3 concentration in the reactor as a function of the O3 exposure were explained by a transition from reaction- to recombination-limited growth. This explanation was validated using a simple plug-flow model. Finally, we estimated the maximum aspect ratios that can be coated for a given O3 recombination probability in O3-based ALD processes using reasonable cycle times
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