Gene flow from the Indian subcontinent to Australia: evidence from the Y chromosome.
(41/669)
Phenotypic similarities between Australian Aboriginal People and some tribes of India were noted by T.H. Huxley during the voyage of the Rattlesnake (1846-1850). Anthropometric studies by Birdsell led to his suggestion that a migratory wave into Australia included populations with affinities to tribal Indians. Genetic evidence for an Indian contribution to the Australian gene pool is contradictory; most studies of autosomal markers have not supported this hypothesis (; and references therein). On the other hand, affinities between Australian Aboriginal People and southern Indians were suggested based on maternally inherited mitochondrial DNA. Here, we show additional DNA evidence in support of Huxley's hypothesis of an Indian-Australian connection using single-nucleotide polymorphisms (SNPs) and short tandem repeats (STRs) on the nonrecombining portion of the Y chromosome (NRY). Phylogenetic analyses of STR variation associated with a major Australian SNP lineage indicated tight clustering with southern Indian/Sri Lankan Y chromosomes. Estimates of the divergence time for these Indian and Australian chromosomes overlap with important changes in the archaeological and linguistic records in Australia. These results provide strong evidence for an influx of Y chromosomes from the Indian subcontinent to Australia that may have occurred during the Holocene. (+info)
Imitation of nonwords by deaf children after cochlear implantation: preliminary findings.
(42/669)
Fourteen prelingually deafened pediatric users of the Nucleus-22 cochlear implant were asked to imitate auditorily presented nonwords. The children's utterances were recorded, digitized, and broadly transcribed. The target patterns and the children's imitations were then played back to normal-hearing adult listeners in order to obtain perceptual judgments of repetition accuracy. The results revealed wide variability in the children's ability to repeat the novel sound sequences. Individual differences in the component processes of encoding, memory, and speech production were strongly reflected in the nonword repetition scores. Duration of deafness before implantation also appeared to be a factor associated with imitation performance. Linguistic analyses of the initial consonants in the nonwords revealed that coronal stops were imitated best, followed by the coronal fricative /s/, and then the labial and velar stops. Labial fricatives were poorly imitated. The theoretical significance of the nonword repetition task as it has been used in past studies of working memory and vocabulary development in normal-hearing children is discussed. (+info)
Methods for characterizing participants' nonmainstream dialect use in child language research.
(43/669)
Three different approaches to the characterization of research participants' nonmainstream dialect use can be found in the literature. They include listener judgment ratings, type-based counts of nonmainstream pattern use, and token-based counts. In this paper, we examined these three approaches, as well as shortcuts to these methods, using language samples from 93 children previously described in J. Oetting and J. McDonald (2001). Nonmainstream dialects represented in the samples included rural Louisiana versions of Southern White English (SWE) and Southern African American English (SAAE). Depending on the method and shortcut used, correct dialect classifications (SWE or SAAE) were made for 88% to 97% of the participants; however, regression algorithms had to be applied to the type- and token-based results to achieve these outcomes. For characterizing the rate at which the participants produced the nonmainstream patterns, the token-based methods were found to be superior to the others, but estimates from all approaches were moderately to highly correlated with each other. When type- and/or token-based methods were used to characterize participants' dialect type and rate, the number of patterns included in the analyses could be substantially reduced without significantly affecting the validity of the outcomes. These findings have important implications for future child language studies that are done within the context of dialect diversity. (+info)
Graded aspects of morphological processing: task and processing time.
(44/669)
Effects on targets of orthographically (O) and semantically (S) related primes were compared with morphologically related (M) primes in the lexical decision, naming, and go/no go naming tasks. The overall pattern typified the graded nature of morphological processing. Morphological relatedness produced facilitation whose magnitude varied across a range of stimulus onset asynchronies (SOAs of 66-300 ms) and tasks. The effect of semantic and orthographic similarity also depended on SOA and on task. Importantly, the effects of morphological relatedness and orthographic similarity diverged along a time course that reflected semantic processing but could only be approximated by the effect of semantic relatedness between prime and target. (+info)
A genetic landscape reshaped by recent events: Y-chromosomal insights into central Asia.
(45/669)
Sixteen Y-chromosomal microsatellites and 16 binary markers have been used to analyze DNA variation in 408 male subjects from 15 populations in Central Asia. Large genetic differences were found between populations, but these did not display an obvious geographical or linguistic pattern like that usually seen for Y-chromosomal variation. Nevertheless, an underlying east-west clinal pattern could be detected by the Autocorrelation Index for DNA Analysis and admixture analysis, and this pattern was interpreted as being derived from the ancient peopling of the area, reinforced by subsequent migrations. Two particularly striking features were seen: an extremely high level of Y-chromosomal differentiation between geographically close populations, accompanied by low diversity within some populations. These were due to the presence of high-frequency population-specific lineages and suggested the occurrence of several recent bottlenecks or founder events. Such events could account for the lack of a clear overall pattern and emphasize the importance of multiple recent events in reshaping this genetic landscape. (+info)
Signal-driven computations in speech processing.
(46/669)
Learning a language requires both statistical computations to identify words in speech and algebraic-like computations to discover higher level (grammatical) structure. Here we show that these computations can be influenced by subtle cues in the speech signal. After a short familiarization to a continuous speech stream, adult listeners are able to segment it using powerful statistics, but they fail to extract the structural regularities included in the stream even when the familiarization is greatly extended. With the introduction of subliminal segmentation cues, however, these regularities can be rapidly captured. (+info)
Spanish personal name variations in national and international biomedical databases: implications for information retrieval and bibliometric studies.
(47/669)
OBJECTIVES: The study sought to investigate how Spanish names are handled by national and international databases and to identify mistakes that can undermine the usefulness of these databases for locating and retrieving works by Spanish authors. METHODS: The authors sampled 172 articles published by authors from the University of Granada Medical School between 1987 and 1996 and analyzed the variations in how each of their names was indexed in Science Citation Index (SCI), MEDLINE, and Indice Medico Espanol (IME). The number and types of variants that appeared for each author's name were recorded and compared across databases to identify inconsistencies in indexing practices. We analyzed the relationship between variability (number of variants of an author's name) and productivity (number of items the name was associated with as an author), the consequences for retrieval of information, and the most frequent indexing structures used for Spanish names. RESULTS: The proportion of authors who appeared under more then one name was 48.1% in SCI, 50.7% in MEDLINE, and 69.0% in IME. Productivity correlated directly with variability: more than 50% of the authors listed on five to ten items appeared under more than one name in any given database, and close to 100% of the authors listed on more than ten items appeared under two or more variants. Productivity correlated inversely with retrievability: as the number of variants for a name increased, the number of items retrieved under each variant decreased. For the most highly productive authors, the number of items retrieved under each variant tended toward one. The most frequent indexing methods varied between databases. In MEDLINE and IME, names were indexed correctly as "first surname second surname, first name initial middle name initial" (if present) in 41.7% and 49.5% of the records, respectively. However, in SCI, the most frequent method was "first surname, first name initial second name initial" (48.0% of the records) and first surname and second surname run together, first name initial (18.3%). CONCLUSIONS: Retrievability on the basis of author's name was poor in all three databases. Each database uses accurate indexing methods, but these methods fail to result in consistency or coherence for specific entries. The likely causes of inconsistency are: (1) use by authors of variants of their names during their publication careers, (2) lack of authority control in all three databases, (3) the use of an inappropriate indexing method for Spanish names in SCI, (4) authors' inconsistent behaviors, and (5) possible editorial interventions by some journals. We offer some suggestions as to how to avert the proliferation of author name variants in the databases. (+info)
Controlling the vocabulary for anatomy.
(48/669)
When confronted with the representation of human anatomy, natural language processing (NLP) system designers are facing an unsolved and frequent problem: the lack of a suitable global reference. The available sources in electronic format are numerous, but none fits adequately all the constraints and needs of language analysis. These sources are usually incomplete, difficult to use or tailored to specific needs. The anatomist's or ontologist's view does not necessarily match that of the linguist. The purpose of this paper is to review most recognized sources of knowledge in anatomy usable for linguistic analysis. Their potential and limits are emphasized according to this point of view. Focus is given on the role of the consensus work of the International Federation of Associations of Anatomists (IFAA) giving the Terminologia Anatomica. (+info)