Language production and implicit statistical learning in typical development and children with acquired language disorders: an exploratory study

Statistical properties of language provide important cues for language learning and may be processed by domain-general cognitive systems. We investigated the relationship between implicit statistical learning (the unconscious detection of statistical regularities in input) and language production. Twenty typically developing (TD) children and nine children with acquired language disorders (ALD) (aged 6–18 years) took part in a Boston Cookie Theft picture description task. Using a computerized analysis, we investigated statistical properties, such as usage frequency of words and collocation strength of word combinations. Participants also completed a non-linguistic serial reaction time (SRT) task, which tested non-verbal, implicit statistical learning in the visual-motor modality. We determined age effects, and compared language production and SRT performance between both groups. Older TD children produced more connected language, more words, less frequent function words, more rare or novel combinations, and showed better statistical learning. Children with ALD produced less connected language, more weakly collocated combinations, displayed less lexical diversity and showed poorer statistical learning. Post-hoc analyses found correlations between statistical learning and statistical properties of spoken language. Given the rarity and heterogeneity of children with ALD, group size was small and the study should be considered exploratory. However, we note that results are compatible with the view that language production draws on statistical learning and that impairment of statistical learning can be related to language disorders

Training flexibility in fixed expressions in non-fluent aphasia: A case series report

Background: Many speakers with non-fluent aphasia (NFA) are able to produce some well-formed word combinations such as ‘I like it’ or ‘I don't know’, although they may not use variations such as ‘He likes it’ or ‘I don't know that person’. This suggests that these utterances represent fixed forms. Aims: This case series investigation explored the impact of a novel intervention aimed at enhancing the connected speech of individuals with NFA. The intervention, motivated by usage-based principles, involved filling open slots in semi-fixed sentence frames. Methods & Procedures: Five participants with NFA completed a 6-week intervention programme. The intervention trained participants to insert a range of different lexical items into the open slots of high-frequency phrases such as ‘I like it’ to enable more productive sentences (e.g., ‘they like flowers’). The outcomes and acceptability were examined: The primary outcome measure focused on changes in connected narrative, and the availability of trained constructions (e.g., ‘I like it’) was explored through a story completion test. Two baseline measures of behaviour were taken prior to intervention, and outcomes assessed immediately after intervention and at a 6-week maintenance assessment. Outcome & Results: A pre-/post-treatment comparison of connected speech measures showed evidence of enhanced connected speech for two of the five participants (P2 and P5). An analysis of story completion test scores revealed positive change for two participants (P1 and P2). Findings were mixed with regard to baseline stability of outcome measures and post-intervention stability of language changes. The intervention was acceptable to all participants. Conclusion & Implications: While this pilot study yielded promising findings with regard to the intervention's acceptability and increased connected speech for some participants, the findings were mixed across the sample of five participants. This research helps inform hypotheses and selection criteria for future studies

Luminescence evidence for bulk and surface excitons in free xenon clusters

Cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying initial experimental parameters, including xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters (about 1500 atoms). The cluster size and temperature (about 40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. A presence of an argon shell causes extinction of the excitonic bands. In addition, some new bands were found which have no analogs for bulk xenon cryosamples.Comment: The final modified version will be published in Phys. Rev. A 76 (2007

Automated profiling of spontaneous speech in primary progressive aphasia and behavioral-variant frontotemporal dementia: An approach based on usage-frequency

Language production provides important markers of neurological health. One feature of impairments of language and cognition, such as those that occur in stroke aphasia or Alzheimer's disease, is an overuse of high frequency, “familiar” expressions. We used computerized analysis to profile narrative speech samples from speakers with variants of frontotemporal dementia (FTD), including subtypes of primary progressive aphasia (PPA). Analysis was performed on language samples from 29 speakers with semantic variant PPA (svPPA), 25 speakers with logopenic variant PPA (lvPPA), 34 speakers with non-fluent variant PPA (nfvPPA), 14 speakers with behavioral variant FTD (bvFTD) and 20 older normal controls (NCs). We used frequency and collocation strength measures to determine use of familiar words and word combinations. We also computed word counts, content word ratio and a combination ratio, a measure of the degree to which the individual produces connected language. All dementia subtypes differed significantly from NCs. The most discriminating variables were word count, combination ratio, and content word ratio, each of which distinguished at least one dementia group from NCs. All participants with PPA, but not participants with bvFTD, produced significantly more frequent forms at the level of content words, word combinations, or both. Each dementia group differed from the others on at least one variable, and language production variables correlated with established behavioral measures of disease progression. A machine learning classifier, using narrative speech variables, achieved 90% accuracy when classifying samples as NC or dementia, and 59.4% accuracy when matching samples to their diagnostic group. Automated quantification of spontaneous speech in both language-led and non-language led dementias, is feasible. It allows extraction of syndromic profiles that complement those derived from standardized tests, warranting further evaluation as candidate biomarkers. Inclusion of frequency-based language variables benefits profiling and classification

Prompt and delayed secondary excitons in rare gas solids

Direct and indirect creation of excitons in rare gas solids has been investigated with reflectivity and luminescence spectroscopy. For the heavy rare gas solids Kr and Xe, new and more reliable exciton parameters have been deduced. With time-resolved luminescence spectroscopy, fast and delayed secondary-exciton creation has been established and separated. Thermalization of photocarriers and their delayed recombination have been analyzed, including a first attempt to investigate the influence of excitation density on the carrier dynamics. The existence of excitonic side bands of ionization limits Ei (either band gap or inner-shell ionization limits) in prompt secondary exciton creation has been established. The threshold energies of these side bands are given by Eth≈Ei nEex (n is integer, Eex is exciton energy). The side bands are ascribed to the formation of electronic polaron complexes, superimposed to inelastic scattering of photoelectrons

Landscape science: a Russian geographical tradition

The Russian geographical tradition of landscape science (landshaftovedenie) is analyzed with particular reference to its initiator, Lev Semenovich Berg (1876-1950). The differences between prevailing Russian and Western concepts of landscape in geography are discussed, and their common origins in German geographical thought in the late nineteenth and early twentieth centuries are delineated. It is argued that the principal differences are accounted for by a number of factors, of which Russia's own distinctive tradition in environmental science deriving from the work of V. V. Dokuchaev (1846-1903), the activities of certain key individuals (such as Berg and C. O. Sauer), and the very different social and political circumstances in different parts of the world appear to be the most significant. At the same time it is noted that neither in Russia nor in the West have geographers succeeded in specifying an agreed and unproblematic understanding of landscape, or more broadly in promoting a common geographical conception of human-environment relationships. In light of such uncertainties, the latter part of the article argues for closer international links between the variant landscape traditions in geography as an important contribution to the quest for sustainability