1,458 research outputs found
The evaluation of partial binocular overlap on car maneuverability: A pilot study
An engineering approach to enlarge the helmet mounted display (HMD) field of view (FOV) and maintain resolution and weight by partially overlapping the binocular FOV has received renewed interest among human factors scientists. It is evident, based on the brief literature review, that any panoramic display with a binocular overlap, less than a minimum amount, annoys the viewer, degrades performance, and elicits undesirable behavior. The major finding is that across the 60 deg conditions, subjects moved their heads a greater distance (by about 5 degs on each side) than in the 180 deg condition, presumably to compensate for the lack of FOV. It is quite clear that the study, based on simple car maneuverability and two subjects, reveals differences in FOV, but nothing significant between binocular overlap levels and configurations. This tentatively indicates that some tradeoffs of binocular vision for a larger overall display FOV are acceptable
TBC1D1 Regulates Insulin- and Contraction-Induced Glucose Transport in Mouse Skeletal Muscle
OBJECTIVE: TBC1D1 is a member of the TBC1 Rab-GTPase family of proteins and is highly expressed in skeletal muscle. Insulin and contraction increase TBC1D1 phosphorylation on phospho-Akt substrate motifs (PASs), but the function of TBC1D1 in muscle is not known. Genetic linkage analyses show a TBC1D1 R125W missense variant confers risk for severe obesity in humans. The objective of this study was to determine whether TBC1D1 regulates glucose transport in skeletal muscle. RESEARCH DESIGN AND METHODS: In vivo gene injection and electroporation were used to overexpress wild-type and several mutant TBC1D1 proteins in mouse tibialis anterior muscles, and glucose transport was measured in vivo. RESULTS: Expression of the obesity-associated R125W mutant significantly decreased insulin-stimulated glucose transport in the absence of changes in TBC1D1 PAS phosphorylation. Simultaneous expression of an inactive Rab-GTPase (GAP) domain of TBC1D1 in the R125W mutant reversed this decrease in glucose transport caused by the R125W mutant. Surprisingly, expression of TBC1D1 mutated to Ala on four conserved Akt and/or AMP-activated protein kinase predicted phosphorylation sites (4P) had no effect on insulin-stimulated glucose transport. In contrast, expression of the TBC1D1 4P mutant decreased contraction-stimulated glucose transport, an effect prevented by concomitant disruption of TBC1D1 Rab-GAP activity. There was no effect of the R125W mutation on contraction-stimulated glucose transport. CONCLUSIONS: TBC1D1 regulates both insulin- and contraction-stimulated glucose transport, and this occurs via distinct mechanisms. The R125W mutation of TBC1D1 impairs skeletal muscle glucose transport, which could be a mechanism for the obesity associated with this mutation
Randomly Crosslinked Macromolecular Systems: Vulcanisation Transition to and Properties of the Amorphous Solid State
As Charles Goodyear discovered in 1839, when he first vulcanised rubber, a
macromolecular liquid is transformed into a solid when a sufficient density of
permanent crosslinks is introduced at random. At this continuous equi- librium
phase transition, the liquid state, in which all macromolecules are
delocalised, is transformed into a solid state, in which a nonzero fraction of
macromolecules have spontaneously become localised. This solid state is a most
unusual one: localisation occurs about mean positions that are distributed
homogeneously and randomly, and to an extent that varies randomly from monomer
to monomer. Thus, the solid state emerging at the vulcanisation transition is
an equilibrium amorphous solid state: it is properly viewed as a solid state
that bears the same relationship to the liquid and crystalline states as the
spin glass state of certain magnetic systems bears to the paramagnetic and
ferromagnetic states, in the sense that, like the spin glass state, it is
diagnosed by a subtle order parameter.
In this review we give a detailed exposition of a theoretical approach to the
physical properties of systems of randomly, permanently crosslinked
macromolecules. Our primary focus is on the equilibrium properties of such
systems, especially in the regime of Goodyear's vulcanisation transition.Comment: Review Article, REVTEX, 58 pages, 3 PostScript figure
Effects of neo-adjuvant chemotherapy for oesophago-gastric cancer on neuro-muscular gastric function
Delayed gastric emptying symptoms are often reported after chemotherapy. This study aims to characterise the effects of chemotherapy on gastric neuro-muscular function. Patients undergoing elective surgery for oesophago-gastric cancer were recruited. Acetylcholinesterase, nNOS, ghrelin receptor and motilin expressions were studied in gastric sections from patients receiving no chemotherapy (n = 3) or oesophageal (n = 2) or gastric (n = 2) chemotherapy. A scoring system quantified staining intensity (0–3; no staining to strong). Stomach sections were separately suspended in tissue baths for electrical field stimulation (EFS) and exposure to erythromycin or carbachol; three patients had no chemotherapy; four completed cisplatin-based chemotherapy within 6 weeks prior to surgery. AChE expression was markedly decreased after chemotherapy (scores 2.3 ± 0.7, 0.5 ± 0.2 and 0 ± 0 in non-chemotherapy, oesophageal- and gastric-chemotherapy groups (p < 0.03 each) respectively. Ghrelin receptor and motilin expression tended to increase (ghrelin: 0.7 ± 0.4 vs 2.0 ± 0.4 and 1.2 ± 0.2 respectively; p = 0.04 and p = 0.2; motilin: 0.7 ± 0.5 vs 2.2 ± 0.5 and 2.0 ± 0.7; p = 0.06 and p = 0.16). Maximal contraction to carbachol was 3.7 ± 0.7 g and 1.9 ± 0.8 g (longitudinal muscle) and 3.4 ± 0.4 g and 1.6 ± 0.6 (circular) in non-chemotherapy and chemotherapy tissues respectively (p < 0.05 each). There were loss of AChE and reduction in contractility to carbachol. The tendency for ghrelin receptors to increase suggests an attempt to upregulate compensating systems. Our study offers a mechanism by which chemotherapy markedly alters neuro-muscular gastric function
Reliability of functional magnetic resonance imaging activation during working memory in a multi-site study: Analysis from the North American Prodrome Longitudinal Study
Multi-site neuroimaging studies offer an efficient means to study brain functioning in large samples of individuals with rare conditions; however, they present new challenges given that aggregating data across sites introduces additional variability into measures of interest. Assessing the reliability of brain activation across study sites and comparing statistical methods for pooling functional data are critical to ensuring the validity of aggregating data across sites. The current study used two samples of healthy individuals to assess the feasibility and reliability of aggregating multi-site functional magnetic resonance imaging (fMRI) data from a Sternberg-style verbal working memory task. Participants were recruited as part of the North American Prodrome Longitudinal Study (NAPLS), which comprises eight fMRI scanning sites across the United States and Canada. In the first study sample (n = 8), one participant from each home site traveled to each of the sites and was scanned while completing the task on two consecutive days. Reliability was examined using generalizability theory. Results indicated that blood oxygen level-dependent (BOLD) signal was reproducible across sites and was highly reliable, or generalizable, across scanning sites and testing days for core working memory ROIs (generalizability ICCs = 0.81 for left dorsolateral prefrontal cortex, 0.95 for left superior parietal cortex). In the second study sample (n = 154), two statistical methods for aggregating fMRI data across sites for all healthy individuals recruited as control participants in the NAPLS study were compared. Control participants were scanned on one occasion at the site from which they were recruited. Results from the image-based meta-analysis (IBMA) method and mixed effects model with site covariance method both showed robust activation in expected regions (i.e. dorsolateral prefrontal cortex, anterior cingulate cortex, supplementary motor cortex, superior parietal cortex, inferior temporal cortex, cerebellum, thalamus, basal ganglia). Quantification of the similarity of group maps from these methods confirmed a very high (96%) degree of spatial overlap in results. Thus, brain activation during working memory function was reliable across the NAPLS sites and both the IBMA and mixed effects model with site covariance methods appear to be valid approaches for aggregating data across sites. These findings indicate that multi-site functional neuroimaging can offer a reliable means to increase power and generalizability of results when investigating brain function in rare populations and support the multi-site investigation of working memory function in the NAPLS study, in particular. (C) 2014 Elsevier Inc. All rights reserved
The IĸB protein BCL3 controls osteogenesis and bone health.
OBJECTIVE: IĸB protein B-cell lymphoma 3-encoded protein (BCL3) is a regulator of the NF-κB family of transcription factors. NF-κB signalling fundamentally influences the fate of bone-forming osteoblasts and bone-resorbing osteoclasts, but the role of BCL3 in bone biology has not been investigated. The objective of this study was to evaluate BCL3 in skeletal development, maintenance and osteoarthritic pathology. METHODS: To assess the contribution of BCL3 to skeletal homeostasis, neonatal mice (n = 6-14) lacking BCL3 (Bcl3-/- ) and WT controls were characterised for bone phenotype and density. To reveal the contribution to bone phenotype by the osteoblast compartment in Bcl3-/- mice, transcriptomic analysis of early osteogenic differentiation and cellular function (n = 3-7) were assessed. Osteoclast differentiation and function in Bcl3-/- mice (n = 3-5) was assessed. Adult 20-week Bcl3-/- and WT mice bone phenotype, strength and turnover were assessed. A destabilisation of the medial meniscus (DMM) model of osteoarthritic ostephytogenesis was utilised to understand adult bone formation in Bcl3-/- mice (n = 11-13). RESULTS: Evaluation of Bcl3-/- mice revealed congenitally increased bone density, long bone dwarfism, increased bone biomechanical strength and altered bone turnover. Molecular and cellular characterisation of mesenchymal precursors showed that Bcl3-/- cells display an accelerated osteogenic transcriptional profile that leads to enhanced differentiation into osteoblasts with increased functional activity; which could be reversed with a mimetic peptide. In a model of osteoarthritis-induced osteophytogenesis, Bcl3-/- mice exhibit decreased pathological osteophyte formation (P < 0.05). CONCLUSION: Cumulatively, these findings demonstrate that BCL3 controls developmental mineralisation to enable appropriate bone formation, whilst in a pathological setting it contributes to skeletal pathology
Networked learning, stepping beyond the net generation and digital natives
This chapter critically examines the idea that young people have undergone a change in which exposure to digital and networked technologies has caused a step change in the character of a whole generation. The empirical and theoretical basis for this argument is reviewed and critical theoretical perspectives are assessed. Evidence from earlier research is compared and contrasted with evidence gathered from students who are said to be part of the new generation. The chapter explores the consequences of these ideas from the standpoint of networked learning. One aim of the chapter is to suggest ways in which the changes that have taken can be more adequately theorized in relation to the idea of networked learning. Arguments used to support generational change rely on a technological determinism and alternative accounts understand young people as active agents. I suggest ex-panding the notion of the agent to include persons enacting roles in collective or-ganizations. Overall the importance of the debate is that determinist arguments can close down debate and networked learning would be impoverished if this occurs
Challenges to alcohol and other drug discussions in the general practice consultation
Background. There is a widely held expectation that GPs will routinely use opportunities to provide opportunistic screening and brief intervention for alcohol and other drug (AOD) abuse, a major cause of preventable death and morbidity
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Fast versus gradual adaptation of soft daily disposable contact lenses in neophyte wearers
Purpose
Despite the widespread practice of gradually adapting all new soft contact lens wearers (neophytes), there is little evidence-based research underpinning such practice. This work determined if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone-hydrogel daily disposable contact lenses.
Method
At four sites, neophytes (19–32 years) were randomly assigned to an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear-time by 2 h on each subsequent day until they had reached 10 h) with hydrogel (n = 24 fast; n = 21 gradual) or silicone-hydrogel (n = 10 fast; n = 10 gradual) contact lenses. Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT). A range of subjective scores (using 0–100 visual analogue scales) were recorded at the initial visit and after 10 h of lens wear, 4–6 days and 12–14 days after initial fitting. Subjective scores were also repeated after 7 days.
Results
There was no difference (p > 0.05) in ocular surface physiology between the fast and gradual adaptation groups at any time point in either lens type. NIBUT was similar at all time points for both adaptation groups in both lens types with the exception that the gradual adaptation silicone-hydrogel wearers had a slightly longer NIBUT (p = 0.007) than the fast adaptation group at 12-14 days. Subjective scores were also similar across the visits and lens types with the exception of ‘lens awareness’ and ‘ease of lens removal’ which were better (p < 0.05) in the fast compared with the gradual adaptation hydrogel lens group at day 7. Additionally, ‘end-of-day discomfort’ was better (p = 0.02) in the fast compared with the gradual adaptation hydrogel lens group at 12–14 days.
Conclusion
There appears to be no benefit in daily disposable soft contact lens adaptation for neophytes with modern contact lens materials
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