Post-traumatic amnesia: Consistency-of-recovery and duration-to-recovery following traumatic brain impairment

The aim of this research was to examine the nature and order of recovery of orientation and memory functioning during Post-Traumatic Amnesia (PTA) in relation to injury severity and PTA duration. The Westmead PTA Scale was used across consecutive testing days to assess the recovery of orientation and memory during PTA in 113 patients. Two new indices were examined: a Consistency-of-Recovery and a Duration-to-Recovery index. a predictable order of recovery was observed during PTA: orientation-to-person recovered sooner and more consistently than the following cluster; orientation-to-time, orientation-to-place, and the ability to remember a face and name. However, the type of memory functioning required for the recall face and name task recovered more consistently than that required for memorizing three pictures. An important overall finding was that the order-of-recovery'' of orientation and memory functioning was dependent upon both the elapsed days since injury, and the consistency of recovery. The newly developed indices were shown to be a valuable means of accounting for differences between groups in the elapsed days to recovery of orientation and memory. These indices also clearly increase the clinical utility of the Westmead PTA Scale and supply an objective means of charting (and potentially predicting) patients' recovery on the different components of orientation and memory throughout their period of hospitalization.

Post-transcriptional regulation of the GLI1 oncogene by the expression of alternative 5 ' untranslated regions

The oncogene GLI1 is involved in the formation of basal cell carcinoma and other tumor types as a result of the aberrant signaling of the Sonic hedgehog-Patched pathway. In this study, we have identified alternative GLI1 transcripts that differ in their 5' untranslated regions (UTRs) and are generated by exon skipping. These are denoted (alpha -UTR, beta -UTR, and gamma -UTR according to the number of noncoding exons possessed (three, two, and one, respectively). The alpha- and beta -UTR forms represent the major Gli1 transcripts expressed in mouse tissues, whereas the gamma -UTR is present at relatively low levels but is markedly induced in mouse skin treated with 12-O-tetradecanoylphorbol 13-acetate, Transcripts corresponding to the murine beta and gamma forms were identified in human tissues, but significantly, only the gamma -UTR form was present in basal cell carcinomas and in proliferating cultures of a keratinocyte cell line. Flow cytometry analysis determined that the gamma -UTR variant expresses a heterologous reporter gene 14-23-fold higher than the alpha -UTR and 5-13-fold higher than the beta -UTR in a variety of cell types. Because expression of the gamma -UTR variant correlates with proliferation, consistent with a role for GLI1 in growth promotion, up-regulation of GLI1 expression through skipping of 5' noncoding exons may be an important tumorigenic mechanism.

The preparation of reach to grasp movements in adults with Down syndrome

The aim of this study was to determine the extent to which adults with Down syndrome (DS) are able to utilise advance information to prepare reach to grasp movements. The study comprised ten adults with DS; ten children matched to an individual in the group with DS on the basis of their intellectual ability, and twelve adult controls. The participants used their right hand to reach out and grasp illuminated perspex blocks. Four target blocks were positioned on a table surface, two to each side of the midsagittal plane. In the complete precue condition, participants were provided with information specifying the location of the target. In the partial precue condition, participants were given advance information indicating the location of the object relative to the midsagittal plane (left or right). In the null condition, advance information concerning the position of the target object was entirely ambiguous. It was found that both reaction times and movement times were greater for the participants with DS than for the adults without DS. The reaction times exhibited by individuals with DS in the complete precue condition were lower than those observed in the null condition, indicating that they had utilised advance information to prepare their movements. In the group with DS, when advance information specified only the location of the target object relative to the midline, reaction times were equivalent to those obtained when ambiguous information was given. In contrast, the adults without DS exhibited reaction times that were lower in both the complete and partial precue conditions when compared to the null condition. The pattern of results exhibited by the children was similar to that of the adults without DS. The movement times exhibited by all groups were not influenced by the precue condition. In summary, our findings indicate that individuals with DS are able to use advance information if it specifies precisely the location of the target object in order to prepare a reach to grasp movement. The group with DS were unable, however, to obtain the normal advantage of advance information specifying only one dimension of the movement goal (i.e., the position of an object relative to the body midline). (C) 2001 Elsevier Science B.V. All rights reserved.

Complex natural resonances of conducting planar objects buried in a dielectric half-space

A scheme is presented to incorporate a mixed potential integral equation (MPIE) using Michalski's formulation C with the method of moments (MoM) for analyzing the scattering of a plane wave from conducting planar objects buried in a dielectric half-space. The robust complex image method with a two-level approximation is used for the calculation of the Green's functions for the half-space. To further speed up the computation, an interpolation technique for filling the matrix is employed. While the induced current distributions on the object's surface are obtained in the frequency domain, the corresponding time domain responses are calculated via the inverse fast Fourier transform (FFT), The complex natural resonances of targets are then extracted from the late time response using the generalized pencil-of-function (GPOF) method. We investigate the pole trajectories as we vary the distance between strips and the depth and orientation of single, buried strips, The variation from the pole position of a single strip in a homogeneous dielectric medium was only a few percent for most of these parameter variations.

Linear models of simple cells: Correspondence to real cell responses and space spanning properties

Despite their limitations, linear filter models continue to be used to simulate the receptive field properties of cortical simple cells. For theoreticians interested in large scale models of visual cortex, a family of self-similar filters represents a convenient way in which to characterise simple cells in one basic model. This paper reviews research on the suitability of such models, and goes on to advance biologically motivated reasons for adopting a particular group of models in preference to all others. In particular, the paper describes why the Gabor model, so often used in network simulations, should be dropped in favour of a Cauchy model, both on the grounds of frequency response and mutual filter orthogonality.

Recent advances in the preparation and utilization of carbon nanotubes for hydrogen storage

Recent progress in the production, purification, and experimental and theoretical investigations of carbon nanotubes for hydrogen storage are reviewed. From the industrial point of view, the chemical vapor deposition process has shown advantages over laser ablation and electric-arc-discharge methods. The ultimate goal in nanotube synthesis should be to gain control over geometrical aspects of nanotubes, such as location and orientation, and the atomic structure of nanotubes, including helicity and diameter. There is currently no effective and simple purification procedure that fulfills all requirements for processing carbon nanotubes. Purification is still the bottleneck for technical applications, especially where large amounts of material are required. Although the alkali-metal-doped carbon nanotubes showed high H-2 Weight uptake, further investigations indicated that some of this uptake was due to water rather than hydrogen. This discovery indicates a potential source of error in evaluation of the storage capacity of doped carbon nanotubes. Nevertheless, currently available single-wall nanotubes yield a hydrogen uptake value near 4 wt% under moderate pressure and room temperature. A further 50% increase is needed to meet U.S. Department of Energy targets for commercial exploitation. Meeting this target will require combining experimental and theoretical efforts to achieve a full understanding of the adsorption process, so that the uptake can be rationally optimized to commercially attractive levels. Large-scale production and purification of carbon nanotubes and remarkable improvement of H-2 storage capacity in carbon nanotubes represent significant technological and theoretical challenges in the years to come.

Post-fledging care, philopatry and recruitment in brown thornbills

1. We describe patterns of post-fledging care, dispersal and recruitment in four cohorts of brown thornbills Acanthiza pusilla. We examine what factors influence post-fledging survival and determine how post-hedging care and the timing of dispersal influence the probability of recruitment in this small, pair breeding, Australian passerine. 2. Fledgling thornbills were dependent on their parents for approximately 6 weeks. Male fledglings were more likely than female fledglings to survive until independence. For both sexes, the probability of reaching independence increased as nestling weight increased and was higher for nestlings that fledged later in the season. 3. The timing of dispersal by juvenile thornbills was bimodal. Juveniles either dispersed by the end of the breeding season or remained on their natal territory into the autumn and winter. Juveniles that delayed dispersal were four times more likely to recruit into the local breeding population than juveniles that dispersed early. 4. Delayed dispersal was advantageous because individuals that remained on their natal territory suffered little mortality and tended to disperse only when a local vacancy was available. Consequently, the risk of mortality associated with obtaining a breeding vacancy using this dispersal strategy was low. 5. Males, the more philopatric sex, were far more likely than females to delay dispersal. Despite the apparent advantages of prolonged natal philopatry, however, only 54% of pairs that raised male fledglings to independence had sons that postponed dispersal, and most of these philopatric sons gained vacancies before their parents bred again. Consequently, few sons have the opportunity to help their parents. Constraints on delayed dispersal therefore appear to play a major role in the evolution of pair-breeding in the brown thornbill.

Post-ruminal protein supply and N retention of weaner sheep fed on a basal diet of lucerne hay (Medicago sativa) with increasing levels of quebracho tannins

The ability of low to moderate levels (