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During puberty young people undergo significant hormonal changes which affect metabolism and, subsequently, health. Evidence suggests there is a period of transient pubertal insulin resistance, with this effect greater in girls than boys. However, the response to everyday high and low glycaemic index (GI) meals remains unknown. Following ethical approval, forty adolescents consumed a high GI or low GI breakfast, in a randomised cross-over design. Capillary blood samples were taken during a 2-h postprandial period, examining the glycaemic and insulinaemic responses. Maturity offset and homoeostatic model assessment (HOMA) were also calculated. The glycaemic response to the breakfasts was similar between boys and girls, as shown by similar peak blood glucose concentrations and incremental AUC (IAUC) following both high and low GI breakfasts (all P>0·05). Girls exhibited a higher peak plasma insulin concentration 30 min post-breakfast following both high GI (P=0·043, g=0·69) and low GI (P=0·010, g=0·84) breakfasts, as well as a greater IAUC following high GI (P=0·041, g=0·66) and low GI (P=0·041, g=0·66) breakfasts. HOMA was positively correlated with the insulinaemic responses (all P<0·0005) and maturity offset (P=0·037). The findings of the present study suggest that pubertal insulin resistance affects the postprandial insulinaemic responses to both high and low GI meals. Specifically, girls exhibit a greater insulinaemic response than boys to both meals, despite similar glycaemic responses. This study is the first to report the glycaemic and insulinaemic responses to everyday meals in boys and girls, supporting the recommendation for young people to base their diet on low GI carbohydrates.
In general, observationally derived wind compositions of WR stars are in reasonable agreement with predictions from stellar evolution models for massive stars. However, Barlow et al. (1988) identified a major discrepancy for neon in γ2 Vel (WC8+O) using ground-based observations. The advent of the ESA Infrared Space Observatory (ISO) has allowed the study of neon in many more WC stars, using mid-IR fine structure lines ([Ne II] 12.81 μm, [NeIII] 15.55μm and [NEV] 14.32 μm). Willis et al. (1998) used ISO-SWS observations of WR 146 (WC5+O) to derive a neon abundance that was within the range expected theoretically. Here we undertake a study of WR 90 (HD 156385), the only (apparently) single WC7 star in our Galaxy, using ISO-SWS spectroscopy. The only spectroscopic neon feature in the mid-IR of WR 90 is [Ne III] 15.55 μm, in addition to numerous C IV and He II transitions (see Figure 1).
Θ phase CuAl2 precipitate size evolution during coarsening at 310°C in 0.5 μm thick Al-2% (wt) Cu thin films was characterized by transmission electron microscopy. Films were sputter deposited onto oxidized Si substrates by standard techniques. The coarsening process preferred the growth of blocky Θ morphologies at Al triple points. Coarsening was via solute Cu diffusion along Al grain boundaries during annealing. The average Θ size dependence on annealing time (t) is approximately (t)1/4 in general agreement with models for particle coarsening along grain boundaries. Concurrent Al grain growth was shown to initially enhance the Θ coarsening rate above (t)1/4 behavior. This boundary coarsening process leads to a grain size dependence of the coarsening rate which has been observed in related and other previous work in thin films. These results are shown to be relevant for effects produced during accelerated electromigration testing, such as previous ‘curious’ 0 morphologies at triple points observed by others, the enhanced flux of Cu during testing, and possible mechanisms affecting electromigration failure processes.
A single nucleotide polymorphism rs12807809 located upstream of the neurogranin (NRGN) gene has been identified as a risk variant for schizophrenia in recent genome-wide association studies. To date, there has been little investigation of the endophenotypic consequences of this variant, and our own investigations have suggested that the effects of this gene are not apparent at the level of cognitive function in patients or controls. Because the impact of risk variants may be more apparent at the level of brain, the aim of this investigation was to delineate whether NRGN genotype predicted variability in brain structure and/or function. Healthy individuals participated in structural (N = 140) and/or functional (N = 36) magnetic resonance imaging (s/fMRI). Voxel-based morphometry was used to compare gray and white matter volumes between carriers of the non-risk C allele (i.e., CC/CT) and those who were homozygous for the risk T allele. Functional imaging data were acquired during the performance of a spatial working memory task, and were also analyzed with respect to the difference between C carriers and T homozygotes. There was no effect of the NRGN variant rs12807809 on behavioral performance or brain structure. However, there was a main effect of genotype on brain activity during performance of the working memory task, such that while C carriers exhibited a load-independent decrease in left superior frontal gyrus/BA10, TT individuals failed to show a similar decrease in activity. The failure to disengage this ventromedial prefrontal region, despite preserved performance, may be indicative of a reduction in processing efficiency in healthy TT carriers. Although it remains to be established whether this holds true in larger samples and in patient cohorts, if valid, this suggests a potential mechanism by which NRGN variability might contribute to schizophrenia risk.
Evidence has accumulated over the past twenty years to suggest that the deep-sea environment is not as constant as was at one time thought, but exhibits temporal variations related to the seasonally in the overlying surface waters. Recent results from deep-moored sediment traps suggest that this coupling is mediated through the sedimentation of organic material, while observations in the Porcupine Seabight indicate that in this region, at least, there is a major and rapid seasonal deposition of aggregated phytodetritus to the sea-floor at slope and abyssal depths.
This paper summarises the results of the Porcupine Seabight studies over the past five years or so, using time-lapse sea-bed photography and microscopic, microbiological and chemical analyses of samples of phytodetritus and of the underlying sediment. The data are to some extent equivocal, but they suggest that the seasonal deposition is a regular and dramatic phenomenon and that the material undergoes relatively little degradation during its passage through the water column. The mechanisms leading to the aggregation of the phytodetritus have not been identified, and it is not yet known whether the phenomenon is geographically widespread nor whether it is of significance to the deep-living mid-water and benthic communities.
Classical plasticity theories generally assume that the stress at a point is a function of strain at that point only. However, when gradients in strain become significant, this localization assumption is no longer valid. These conventional models fail to display a ‘size effect’. This effect is seen experimentally when the scale of the phenomenon of interest is on the order of several microns. Under these conditions, strain gradients are of a significant magnitude as compared to the overall strain and must be considered for models to accurately capture observed phenomena.
The mechanics community has been actively involved in the development of strain gradient theories for many years. Recently, interest in this area has been rekindled and several new approaches have appeared in the literature. Two different approaches are currently being evaluated. One approach considers strain gradients as internal variables that do not introduce work conjugate higher order stresses. Another approach considers the strain gradients as internal degrees of freedom that requires work conjugate higher order stresses. Experiments are being performed to determine which approach models material behavior accurately with the least amount of complexity. A key difference between the two models considered here is the nature of the assumed boundary conditions at material interfaces. Therefore, we are investigating the deformation behavior of aluminum/sapphire interfaces loaded under simple shear. Samples are fabricated using ultra-high vacuum diffusion bonding. To determine the lattice rotations near the boundary, we are examining the samples with both electron backscatter diffraction methods (EBSD) in the scanning electron microscope and with a variety of diffraction techniques in the transmission electron microscope. The experimentally found boundary conditions shall be subsequently used to determine whether the simpler internal variable model is adequately descriptive or if the greater complexity associated with the internal degree of freedom approach is warranted.
Rheology and the component interactions which affect rheology were studied for a tape casting composition similar to commercial systems. Viscosity measurements at different shear rates were compared to measured tape properties to determine if high or low shear rate rheological behavior controls tape characteristics. Relative viscosity was measured to assess the contribution of each component to the stability of the dispersion.
Interconnect reliability is of continuing concern in modem VLSI circuits. This work presents analyses of the microstructural detail in electromigration-induced damage in Al and Al-Cu unpassivated interconnects. Such failure analysis is crucial for the characterization of the fundamental processes responsible for failure. Results, via TEM, SEM and focussed-ion beam techniques, suggest possible second phase precipitate-void growth interactions, show slit-like open circuit failures in narrow interconnects, and illustrate the microstructures of hillocks and whiskers formed during accelerated electromigration testing. These results are discussed in terms of existing models for electromigration failure processes and lifetimes. The results are further intended to suggest mechanisms for future modelling and to direct the design of more reliable interconnect material systems.
Cognitive training improves mental abilities in older adults, but the trainability of persons with memory impairment is unclear. We conducted a subgroup analysis of subjects in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) trial to examine this issue. ACTIVE enrolled 2802 non-demented, community-dwelling adults aged 65 years and older and randomly assigned them to one of four groups: Memory training, reasoning training, speed-of-processing training, or no-contact control. For this study, participants were defined as memory-impaired if baseline Rey Auditory Verbal Learning Test (AVLT) sum recall score was 1.5 SD or more below predicted AVLT sum recall score from a regression-derived formula using age, education, ethnicity, and vocabulary from all subjects at baseline. Assessments were taken at baseline (BL), post-test, first annual (A1), and second annual (A2) follow-up. One hundred and ninety-three subjects were defined as memory-impaired and 2580 were memory-normal. Training gain as a function memory status (impaired vs. normal) was compared in a mixed effects model. Results indicated that memory-impaired participants failed to benefit from Memory training but did show normal training gains after reasoning and speed training. Memory function appears to mediate response to structured cognitive interventions in older adults. (JINS, 2007, 13, 953–960.)
We report the cloning and sequencing of a DNA fragment encoding a putative C2H2 zinc finger protein from Aspergillus nidulans. The gene was isolated by complementation cloning of a salt sensitive phenotype of the A. nidulans sltA1 mutant. A 3·8 kb PstI fragment that restored wild type salt tolerance contained one large open reading frame of 2202 bp. The predicted protein (StzA) from this reading frame comprises 698 amino acids and has three Zinc fingers along with a putative transcriptional activation domain rich in acidic amino acids. The corresponding sequence from a sltA1 mutant contains a premature STOP codon resulting in loss of the putative transcriptional activator in the C-terminal region. The Zinc fingers show conserved motifs with a number of transcription factors including CreA from A. nidulans and the human Wilm's tumour susceptibility protein WT-1.
Thirty-three strains of Fusarium species from clinical sources including F. solani, F. oxysporum, F. moniliforme, F. proliferatum,
F. subglutinans and F. chlamydosporum were examined for their physiological characteristics and mycotoxin production. Of this collection
29 exhibited growth at 37 °C and 21 were resistant to cycloheximide. Two strains of F. moniliforme and two strains of F. proliferatum
produced fumonisins. No strains in this collection produced detectable amounts of trichothecenes. All 18 strains of F. solani tested
produced the immunosuppressive agent cyclosporin A. The cyclosporin A-producing ability of clinical isolates of F. solani may
influence their pathogenic potential.
Studies of speed of cognitive processing in Parkinson's
disease (PD) have yielded mixed results. This may relate
in part to a differential effect on cognitive speed by
the type of information to be processed. In the present
study, we compared medication fasted, nondemented individuals
with mild idiopathic PD (N = 26) with age-matched
controls (N = 12) on a test requiring easy and
hard same–different discriminations for verbal, quantitative,
and spatial information, as well as on a traditional memory
scanning paradigm. A voice-activated relay rather than
a key press was used to eliminate the need for limb and
finger movements. Simple reaction time and movement time
were also measured in a task requiring subjects to move
a hand held stylus to a designated target. The PD group
performed as fast as the control group across all tasks
except movement time. Thus, in our paradigm, the presence
of PD alone does not predict cognitive slowing in the presence
of motor slowing. (JINS, 1998, 4, 584–592.)