Protein dose requirements to maximize skeletal muscle protein synthesis after repeated bouts of resistance exercise in young trained women.

Studies examining the effect of protein (PRO) feeding on post resistance exercise (RE) muscle protein synthesis (MPS) have primarily been performed in men, and little evidence is available regarding the quantity of PRO required to maximally stimulate MPS in trained women following repeated bouts of RE. We therefore quantified acute (4 h and 8 h) and extended (24 h) effects of two bouts of resistance exercise, alongside protein-feeding, in women, and the PRO requirement to maximize MPS. Twenty-four RE trained women (26.6 ± 0.7 years, mean ± SEM) performed two bouts of whole-body RE (3 × 8 repetitions/maneuver at 75% 1-repetition maximum) 4 h apart, with post-exercise ingestion of 15 g, 30 g, or 60 g whey PRO (n = 8/group). Saliva, venous blood, and a vastus lateralis muscle biopsy were taken at 0 h, 4 h, 8 h, and 24 h post-exercise. Plasma leucine and branched chain amino acids were quantified using gas chromatography mass spectrometry (GC-MS) after ingestion of D2 O. Fifteen grams PRO did not alter plasma leucine concentration or myofibrillar synthetic rate (MyoFSR). Thirty and sixty grams PRO increased plasma leucine concentration above baseline (105.5 ± 5.3 µM; 120.2 ± 7.4 µM, respectively) at 4 h (151.5 ± 8.2 µM, p < 0.01; 224.8 ± 16.0 µM, p < 0.001, respectively) and 8 h (176.0 ± 7.3 µM, p < 0.001; 281.7 ± 21.6 µM, p < 0.001, respectively). Ingestion of 30 g PRO increased MyoFSR above baseline (0.068 ± 0.005%/h) from 0 to 4 h (0.140 ± 0.021%/h, p < 0.05), 0 to 8 h (0.121 ± 0.012%/h, p < 0.001), and 0 to 24 h (0.099 ± 0.011%/h, p < 0.01). Ingestion of 60 g PRO increased MyoFSR above baseline (0.063 ± 0.003%/h) from 0 to 4 h (0.109 ± 0.011%/h, p < 0.01), 0 to 8 h (0.093 ± 0.008%/h, p < 0.01), and 0 to 24 h (0.086 ± 0.006%/h, p < 0.01). Post-exercise ingestion of 30 g or 60 g PRO, but not 15 g, acutely increased MyoFSR following two consecutive bouts of RE and extended the anabolic window over 24 h. There was no difference between the 30 g and 60 g responses.

Synaptic dynamics in complex self-assembled nanoparticle networks.

We report a detailed study of neuromorphic switching behaviour in inherently complex percolating networks of self-assembled metal nanoparticles. We show that variation of the strength and duration of the electric field applied to this network of synapse-like atomic switches allows us to control the switching dynamics. Switching is observed for voltages above a well-defined threshold, with higher voltages leading to increased switching rates. We demonstrate two behavioral archetypes and show how the switching dynamics change as a function of duration and amplitude of the voltage stimulus. We show that the state of each synapse can influence the activity of the other synapses, leading to complex switching dynamics. We further demonstrate the influence of the morphology of the network on the measured device properties, and the constraints imposed by the overall network conductance. The correlated switching dynamics, device stability over long periods, and the simplicity of the device fabrication provide an attractive pathway to practical implementation of on-chip neuromorphic computing.

Muscle thickness correlates to muscle cross-sectional area in the assessment of strength training-induced hypertrophy.

Muscle thickness (MT) measured by ultrasound has been used to estimate cross-sectional area (measured by CT and MRI) at a single time point. We tested whether MT could be used as a valid marker of MRI determined muscle anatomical cross-sectional area (ACSA) and volume changes following resistance training (RT). Nine healthy, young, male volunteers (24 ± 2 y.o., BMI 24.1 ± 2.8 kg/m2 ) had vastus lateralis (VL) muscle volume (VOL) and ACSAmid (at 50% of femur length, FL) assessed by MRI, and VL MT measured by ultrasound at 50% FL. Measurements were taken at baseline and after 12 weeks of isokinetic RT. Differences between baseline and post-training were assessed by Student's paired t test. The relationships between MRI and ultrasound measurements were tested by Pearson's correlation. After RT, MT increased by 7.5 ± 6.1% (P < .001), ACSAmid by 5.2 ± 5% (P < .001), and VOL by 5.0 ± 6.9% (P < .05) (values: means ± SD). Positive correlations were found, at baseline and 12 weeks, between MT and ACSAmid (r = .82, P < .001 and r = .73, P < .001, respectively), and between MT and VOL (r = .76, P < .001 and r = .73, P < .001, respectively). The % change in MT with training was correlated with % change in ACSAmid (r = .69, P < .01), but not % change in VOL (r = .33, P > .05). These data support evidence that MT is a reliable index of muscle ACSAmid and VOL at a single time point. MT changes following RT are associated with parallel changes in muscle ACSAmid but not with the changes in VOL, highlighting the impact of RT on regional hypertrophy.

Reservoir computing using networks of memristors: effects of topology and heterogeneity.

Reservoir computing (RC) has attracted significant interest as a framework for the implementation of novel neuromorphic computing architectures. Previously attention has been focussed on software-based reservoirs, where it has been demonstrated that reservoir topology plays a role in task performance, and functional advantage has been attributed to small-world and scale-free connectivity. However in hardware systems, such as electronic memristor networks, the mechanisms responsible for the reservoir dynamics are very different and the role of reservoir topology is largely unknown. Here we compare the performance of a range of memristive reservoirs in several RC tasks that are chosen to highlight different system requirements. We focus on percolating networks of nanoparticles (PNNs) which are novel self-assembled nanoscale systems that exhibit scale-free and small-world properties. We find that the performance of regular arrays of uniform memristive elements is limited by their symmetry but that this symmetry can be broken either by a heterogeneous distribution of memristor properties or a scale-free topology. The best perfomance across all tasks is observed for a scale-free network with uniform memistor properties. These results provide insight into the role of topology in neuromorphic reservoirs as well as an overview of the computational performance of scale-free networks of memristors in a range of benchmark tasks.

Reservoir computing with 3D nanowire networks.

Networks of nanowires are currently being explored for a range of applications in brain-like (or neuromorphic) computing, and especially in reservoir computing (RC). Fabrication of real-world computing devices requires that the nanowires are deposited sequentially, leading to stacking of the wires on top of each other. However, most simulations of computational tasks using these systems treat the nanowires as 1D objects lying in a perfectly 2D plane - the effect of stacking on RC performance has not yet been established. Here we use detailed simulations to compare the performance of perfectly 2D and quasi-3D (stacked) networks of nanowires in two tasks: memory capacity and nonlinear transformation. We also show that our model of the junctions between nanowires is general enough to describe a wide range of memristive networks, and consider the impact of physically realistic electrode configurations on performance. We show that the various networks and configurations have a strikingly similar performance in RC tasks, which is surprising given their radically different topologies. Our results show that networks with an experimentally achievable number of electrodes perform close to the upper bounds achievable when using the information from every wire. However, we also show important differences, in particular that the quasi-3D networks are more resilient to changes in the input parameters, generalizing better to noisy training data. Since previous literature suggests that topology plays an important role in computing performance, these results may have important implications for future applications of nanowire networks in neuromorphic computing.

Avalanches and criticality in self-organized nanoscale networks.

Current efforts to achieve neuromorphic computation are focused on highly organized architectures, such as integrated circuits and regular arrays of memristors, which lack the complex interconnectivity of the brain and so are unable to exhibit brain-like dynamics. New architectures are required, both to emulate the complexity of the brain and to achieve critical dynamics and consequent maximal computational performance. We show here that electrical signals from self-organized networks of nanoparticles exhibit brain-like spatiotemporal correlations and criticality when fabricated at a percolating phase transition. Specifically, the sizes and durations of avalanches of switching events are power law distributed, and the power law exponents satisfy rigorous criteria for criticality. These signals are therefore qualitatively and quantitatively similar to those measured in the cortex. Our self-organized networks provide a low-cost platform for computational approaches that rely on spatiotemporal correlations, such as reservoir computing, and are an important step toward creating neuromorphic device architectures.

Trimethylamine dehydrogenase from a methylotrophic bacterium. I. Isolation and steady-state kinetics.

1. The isolation of trimethylamine dehydrogenase (EC 1.5.99.7) from a restricted facultative methylotroph to electrophoretic homogeneity is described. 2. The molecular weight and subunit molecular weights were found to be 146800 for the enzyme by sedimentation equilibrium ultracentrifugation and 70000-80000 for the two non-identical subunits by sodium dodecyl sulphate gel electrophoresis. 3. Initial velocity studies indicate that the enzymatic reaction proceeds by a Ping-Pong mechanism. 4. Further kinetic evidence was obtained by analysis of product inhibition patterns using the alternate substrate diethylamine and the products acetaldehyde and ethylamine as product inhibitors, for the release of ethylamine before the addition of phenazine methosulphate and for the existence of an enzyme-two-carbon unit complex as a stable form of the enzyme. 5. Some properties of the unusual prosthetic group of trimethylamine dehydrogenase and its photodegradation product are described in preliminary form.

A 7-year review of deaths on the general paediatric wards at John Hunter Children's Hospital, 1991-97.

OBJECTIVE: To study the palliative management of children dying on the wards of a tertiary referral centre. In particular to identify areas of difficulty and discuss ways in which these can be improved. METHODOLOGY: All children between the ages 1 and 19 years dying on the general paediatric wards of the John Hunter Children's Hospital (JHCH) (a tertiary referral centre in New South Wales Hunter Valley) between 1991 and 1998 were included in the study. The main outcome measures were the duration of 'terminal care only' treatment; time spent in hospital in the previous year; analgesia used, dose and route of administration; adjuvant medications; quality of life in the final 24 h. RESULTS: Eighteen children (aged between 1 and 19 years) died on the general paediatric wards at JHCH between 1991 and 1998. The most common diagnosis was malignancy (five patients), with cystic fibrosis, cerebral palsy and a degenerative neurological disorder each accounting for four patients, and one child had herpes simplex encephalitis. In all children the terminal nature of their condition was recognized and in all but three patients there was documentation of 'not for resuscitation' (NFR) orders following discussion with the child's parents. The mainstay of analgesia was an intravenous narcotic infusion with 11 (61%) children needing a morphine infusion. Fifteen patients (83%) required other medications including antiemetics, anticonvulsants and corticosteroids. Twelve (66%) children were semiconscious or unconscious on the day of death. Three children were uncomfortable and distressed, one alert and symptom free and in two cases the level of consciousness was not recorded. Three children continued to have seizures until their death. CONCLUSION: The majority of terminally ill children were managed well with intravenous narcotics and adjuvant medications. There may be scope for such children to be managed successfully at home with appropriate support for the general practitioner by paediatric and palliative care specialists. Some cases in which palliation is difficult do remain in hospital and additional measures need to be employed to ensure a symptom free death for these children.