21 resultados para SLOW

em Deakin Research Online - Australia


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Despite the significant Requirements Engineering (RE) research efforts over the past decade the research--industry gap still remains persistent.
Recent attempts by the RE research community to address this issue include cumulative knowledge studies to describe the current state of RE research and the establishment of a new conference dedicated to the comparative evaluation of RE.
This paper reports the state of RE research from 2001 to 2005. A taxonomy of RE literature is presented and a conceptual framework for
understanding the current state of RE is also described. The ensuing analysis shows that during the period 2001-2005 there was only an incremental development of RE research without any radical theoretical contributions to its body of knowledge. The paper also poses a challenge for the RE research community to respond to the dramatic changes in the
social and business world.

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Examines the relationship between the magnitude of the relative slow component (SC) of pulmonary oxygen uptake VO[sub 2], citrate synthase activity, UCP2 and UCP3 mRNA levels and muscle fiber composition in both endurance-trained and recreationally active subjects. Magnitude of the relative SC of the Tr group; Indicators of aerobic fitness; High negative correlations between the magnitude of the relative SC and citrate synthase activity and VO[sub 2] peak.

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This investigation was undertaken to determine if there are altered histological, pathological and contractile properties in presymptomatic or endstage diseased muscle fibres from representative slow-twitch and fast-twitch muscles of SOD1 G93A mice in comparison to wildtype mice. In presymptomatic SOD1 G93A mice, there was no detectable peripheral dysfunction, providing evidence that muscle pathology is secondary to motor neuronal dysfunction. At disease endstage however, single muscle fibre contractile analysis demonstrated that fast-twitch muscle fibres and neuromuscular junctions are preferentially affected by amyotrophic lateral sclerosis-induced denervation, being unable to produce the same levels of force when activated by calcium as muscle fibres from their age-matched controls. The levels of transgenic SOD1 expression, aggregation state and activity were also examined in these muscles but there no was no preference for muscle fibre type. Hence, there is no simple correlation between SOD1 protein expression/activity, and muscle fibre type vulnerability in SOD1 G93A mice.

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The aim of this study was to compare the oxygen uptake (VO^sub 2^) slow component (SC) during level and uphill running in endurance runners, and to identify associations between the SC and the following aerobic fitness indicators: peak VO^sub 2^, running speed associated with the peak VO^sub 2^ (Vpeak), running speed at the lactic threshold and the VO^sub 2^ fraction elicited at the lactic threshold. Fourteen male endurance-trained runners underwent several 6-min bouts of level (LTR) and 10.5% uphill treadmill running. VO^sub 2^ SC was calculated as the difference between mean VO^sub 2^ during the 6th and the 3rd minutes. The highest mean values for the SC were 181.9±240.2 mL*min^sup -1^ for level running at ~94% peak VO^sub 2^ and 105.4±154.6 mL*min^sup -1^ for uphill running at ~90% peak VO^sub 2^. The SC observed during the last bout of the LTR correlated with peak VO^sub 2^ and with Vpeak (-0.71 and -0.76, P<0.05, respectively). The results show that for endurance-trained runners the magnitude of the SC is not affected by the treadmill gradient and that within a homogeneous sample of endurance-trained runners the SC does not correlate with indicators of aerobic fitness.

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Damaged skeletal muscle fibres are replaced with new contractile units via muscle regeneration. Regenerating muscle fibres synthesize functionally distinct isoforms of contractile and regulatory proteins but little is known of their functional properties during the regeneration process. An advantage of utilizing single muscle fibre preparations is that assessment of their function is based on the overall characteristics of the contractile apparatus and regulatory system and as such, these preparations are sensitive in revealing not only coarse, but also subtle functional differences between muscle fibres. We examined the Ca2+- and Sr2+-activated contractile characteristics of permeabilized fibres from rat fast-twitch (extensor digitorum longus) and slow-twitch (soleus) muscles at 7, 14 and 21 days following myotoxic injury, to test the hypothesis that fibres from regenerating fast and slow muscles have different functional characteristics to fibres from uninjured muscles. Regenerating muscle fibres had ∼10% of the maximal force producing capacity (Po) of control (uninjured) fibres, and an altered sensitivity to Ca2+ and Sr2+ at 7 days post-injury. Increased force production and a shift in Ca2+ sensitivity consistent with fibre maturation were observed during regeneration such that Po was restored to 36–45% of that in control fibres by 21 days, and sensitivity to Ca2+ and Sr2+ was similar to that of control (uninjured) fibres. The findings support the hypothesis that regenerating muscle fibres have different contractile activation characteristics compared with mature fibres, and that they adopt properties of mature fast- or slow-twitch muscle fibres in a progressive manner as the regeneration process is completed.

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1. Studies have shown that, in isolated skeletal muscles, maximum isometric force production (Po) is dependent on muscle redox state. Endurance training increases the antioxidant capacity of skeletal muscles, a factor that could impact on the force-producing capacity following exogenous exposure to an oxidant. We tested the hypothesis that 12 weeks treadmill training would increase anti-oxidant capacity in rat skeletal muscles and alter their response to exogenous oxidant exposure.

2. At the conclusion of the 12 week endurance-training programme, soleus (slow-twitch) muscles from trained rats had greater citrate synthase (CS) and catalase (CAT) activity compared with soleus muscles from untrained rats (P < 0.05).
In contrast, CAT activity of extensor digitorum longus (EDL; fast-twitch) muscles from trained rats was not different to EDL muscles of untrained rats. The CS activity was lower in EDL muscles from trained compared with untrained rats (P < 0.05).

3. Equilibration with exogenous hydrogen peroxide (H2O2, 5 mmol/L) increased the Po of soleus muscles from untrained rats for the duration of treatment (30 min), whereas the Po of EDL muscles was affected biphasically, with a small increase initially (after 5 min), followed by a more marked decrease in Po (after 30 min). The H2O2-induced increase in Po of soleus muscles from trained rats was less than that in untrained rats (P < 0.05), but no differences were observed in the Po of EDL muscles following training.

4. The results indicate that 12 weeks endurance running training conferred adaptations in soleus but not EDL muscles. These adaptations were associated with an attenuation of the oxidant-induced increase in Po of soleus muscles from trained compared with untrained rats. We conclude that endurance training-adapted soleus muscles have a slightly altered redox - force relationship.

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Fifteen trained male cyclists had muscle biopsies and performed cycling tests to determine if relationships exist between the oxygen uptake response and various intramuscular variables. It was found that muscle oxidative capacity is better able to explain the oxygen uptake response during high intensity cycling than muscle fiber distribution.

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We generated a mouse line with a missense mutation (S248F) in the gene (CHRNA4) encoding the α4 subunit of neuronal nicotinic acetylcholine receptor (nAChR). Mutant mice demonstrate brief nicotine induced dystonia that resembles the clinical events seen in patients with the same mutation. Drug-induced dystonia is more pronounced in female mice, thus our aim was to determine if the S248F mutation changed the properties of fast- and slow-twitch muscle fibres from female mutant mice. Reverse transcriptase-PCR confirmed CHRNA4 gene expression in the brain but not skeletal muscles in normal and mutant mice. Ca2+ and Sr2+ force activation curves were obtained using skinned muscle fibres prepared from slow-twitch (soleus) and fast-twitch (EDL) muscles. Two significant results were found: (1) the (pCa50 - pSr50) value from EDL fibres was smaller in mutant mice than in wild type (1.01 vs. 1.30), (2) the percentage force produced at pSr 5.5 was larger in mutants than in wild type (5.76 vs. 0.24%). Both results indicate a shift to slow-twitch characteristics in the mutant. This conclusion is supported by the identification of the myosin heavy chain (MHC) isoforms. Mutant EDL fibres expressed MHC I (usually only found in slow-twitch fibres) as well as MHC IIa. Despite the lack of spontaneous dystonic events, our findings suggest that mutant mice may be having subclinical events or the mutation results in a chronic alteration to muscle neural input.

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Objective To determine the benefits of a low intensity parent-toddler language promotion programme delivered to toddlers identified as slow to talk on screening in universal services.
Design Cluster randomised trial nested in a population based survey.
Setting Three local government areas in Melbourne, Australia.
Participants Parents attending 12 month well child checks over a six month period completed a baseline questionnaire. At 18 months, children at or below the 20th centile on an expressive vocabulary checklist entered the trial.
Intervention Maternal and child health centres (clusters) were randomly allocated to intervention (modified “You Make the Difference” programme over six weekly sessions) or control (“usual care”) arms.
Main outcome measures The primary outcome was expressive language (Preschool Language Scale-4) at 2 and 3 years; secondary outcomes were receptive language at 2 and 3 years, vocabulary checklist raw score at 2 and 3 years, Expressive Vocabulary Test at 3 years, and Child Behavior Checklist/1.5-5 raw score at 2 and 3 years.
Results 1217 parents completed the baseline survey; 1138 (93.5%) completed the 18 month checklist, when 301 (26.4%) children had vocabulary scores at or below the 20th centile and were randomised (158 intervention, 143 control). 115 (73%) intervention parents attended at least one session (mean 4.5 sessions), and most reported high satisfaction with the programme. Interim outcomes at age 2 years were similar in the two groups. Similarly, at age 3 years, adjusted mean differences (intervention−control) were −2.4 (95% confidence interval −6.2 to 1.4; P=0.21) for expressive language; −0.3 (−4.2 to 3.7; P=0.90) for receptive language; 4.1 (−2.3 to 10.6; P=0.21) for vocabulary checklist; −0.5 (−4.4 to 3.4; P=0.80) for Expressive Vocabulary Test; −0.1 (−1.6 to 1.4; P=0.86) for externalising behaviour problems; and −0.1 (−1.3 to 1.2; P=0. 92) for internalising behaviour problems.
Conclusion This community based programme targeting slow to talk toddlers was feasible and acceptable, but little evidence was found that it improved language or behaviour either immediately or at age 3 years.

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The Group of Eight research universities are tough institutions for disadvantaged students to get into, but they are not, according to a surprising new study, the toughest of the lot: that dubious honour goes to the University of Canberra.