Interpersonal exchanges in discussion forums: A study of learning communities in distance learning settings

Cooperative relationships are the foundation of a model of online learning based on communities. The development of a community depends on the interaction between community members. This study is based on the belief that the dynamics of exchange of thought, from a Piagetian perspective, are one possibility for understanding the process of interaction within a virtual community. The study therefore investigates the dynamics of conversations in discussion forums in order to lead to an understanding of the processes involved in the formation of virtual learning communities. The research path involved content analysis of messages, interaction mapping and an analysis of the relationship between them. The results indicate that there is a relationship between the texts of discussion forum messages and continuation of interpersonal exchanges.     

Gene structure of the human MET proto-oncogene

By direct sequencing of cosmids using primers designed from the known cDNA sequence, we identified 19 exons in the human MET proto-oncogene, and sequenced the corresponding 5' and 3' exon-intron junctions. By homology search in the database of the Washington University Genome Sequence Center (GSC), we identified one additional exon. These 20 exons, together with a previously reported exon, bring the total exon number of MET to 21. Oligonucleotide primers were designed to amplify each exon and adjacent intronic sequences to permit examination of each exon for mutations. By restriction mapping, we assembled a 110 kb genomic contig that covered almost the entire MET proto-oncogene. This information is relevant for the screening of recently reported mutations of the MET gene which cause hereditary papillary renal carcinomas and for the search for additional mutations of the same gene which may play a role in the pathogenesis of common human carcinomas including carcinomas of the breast, ovary and pancreas.     

Alternate finger tapping test in patients with migraine

Out of 2494 subjects screened in a Nigerian community, 28 patients with dementia were identified. Alzheimer's disease was diagnosed in 18 patients (64.3%), 16 of whom had probable Alzheimer's disease. Eight patients (28.6%) had vascular dementia while one patient each had parkinsonism with dementia and depression with dementia. Patients with Alzheimer's disease were significantly older, predominantly females and illiterates. Cognitive deficit commonly took the form of memory and judgment impairment while financial mismanagement was the most frequent impaired activity of daily living. More than half of the cases had mild disease on severity rating and were comprised mainly of Alzheimer's disease subjects. These results confirm the higher frequency of Alzheimer's disease over the other types as reported in other communities.     

Knowledge based support for manufacturing of microstructures

 In the Institute of Applied Computer Science (IAI) in the Forschungszentrum Karlsruhe (FZK) information technologies are developed and applied to support the design and manufacturing process for micromechanical structures. The information related kernel of the computer integrated manufacturing (CIM) consists of different semantic domains. At the beginning of the whole manufacturing process, the designer has to construct the microstructure with a CAD system for mechanical construction. After application of design rule checks, based on heuristics from human experts, these constructions are the references for the quality control of the real fabricated structures. The knowledge in form of design rules needs as well deeper knowledge, stored in the different partial modes of the process model and the product model as well dynamical results of the different integrated tools for design, simulation and optimization. Especially this fact is the kernel to produce cost efficient because distinguishing between possible and impossible structures in a very early stage of manufacturing. Received: 30 October 1995 / Accepted: 20 May 1996     

Timecourse of development of the wallaby trigeminal pathway. I. Periphery to brainstem

The development of the vibrissae and their innervation and the maturation of the brainstem trigeminal sensory nuclei have been studied in the wallaby, Macropus eugenii, from birth to adulthood. At birth, developing vibrissal follicles consist of solid epidermal pegs surrounded by dermal condensations. The developing follicles and adjacent skin are innervated by trigeminal afferents. Ten days after birth the follicle contains a dermal papilla and the deep vibrissal nerve can be recognised. A hair cone is present at postnatal day (P) 30 and hairs are apparent on the skin surface by P35. By P63 the deep vibrissal nerve can be seen innervating Merkel cells in the outer root sheath; in addition, the first signs of the blood sinus can be recognised. Innervation of the inner conical body and lanceolate and lamellated receptors supplying the mesenchymal sheath and waist region are not seen until P119, when the follicle resembles that seen in the adult. At birth, central processes of the trigeminal ganglion cells have entered the trigeminal tract and extend from the rostral pons to the upper cervical cord. Labelling with a carbocyanine dye at P0 shows afferents extending medially from the tract into the trigeminal subnuclei at all levels. At this stage the trigeminal nuclei appear as areas of increased cell density in the lateral brainstem. By P30-40 the four subnuclei can be distinguished on the basis of shape, cytoarchitecture, and succinic dehydrogenase reactivity. Adult morphology is not fully established until P210. In mature animals, nucleus principalis contains closely packed, polymorphic cells, frequently aligned parallel to thick fibre bundles that traverse the nucleus obliquely. Subnuclei oralis and interpolaris contain sparsely distributed, medium to large cells, randomly oriented, as well as prominent rostrocaudally directed fibre bundles. Subnucleus caudalis consists of the marginal layer, substantia gelatinosa, and magnocellular layers as described in other species. Patches of increased succinic dehydrogenase or cytochrome oxidase reactivity, presumably corresponding to the vibrissae, are present in subnuclei principalis, interpolaris, and caudalis in developing and adult animals, although the pattern is less clear than in rats. The brainstem patches are first seen at P40, approximately 6 weeks before the corresponding vibrissal-related pattern develops in the cortex. This suggests that the onset of patch formation may be regulated independently at different levels of the pathway.     

Molecular analysis of the PDS gene in Pendred syndrome

Pendred syndrome is an autosomal recessive disorder characterized by the association between sensorineural hearing loss and thyroid swelling or goitre and is likely to be the most common form of syndromic deafness. Within the thyroid gland of affected individuals, iodide is incompletely organified with variable effects upon thyroid hormone biosynthesis, whilst the molecular basis of the hearing loss is unknown. The PDS gene has been identified by positional cloning of chromosome 7q31, within the Pendred syndrome critical linkage interval and encodes for a putative ion transporter called pendrin. We have investigated a cohort of 56 kindreds, all with features suggestive of a diagnosis of Pendred syndrome. Molecular analysis of the PDS gene identified 47 of the 60 (78%) mutant alleles in 31 families (includes three homozygous consanguineous kindreds and one extended family segregating three mutant alleles). Moreover, four recurrent mutations accounted for 35 (74%) of PDS disease chromosomes detected and haplotype analysis would favour common founders rather than mutational hotspots within the PDS gene. Whilst these findings demonstrate molecular heterogeneity for PDS mutations associated with Pendred syndrome, this study would support the use of molecular analysis of the PDS gene in the assessment of families with congenital hearing loss.