The importance of different timings of excitatory and inhibitory pathways in neural field models

In this paper, we consider a neural field model comprised of two distinct populations of neurons, excitatory and inhibitory, for which both the velocities of action potential propagation and the time courses of synaptic processing are different. Using recently-developed techniques, we construct the Evans function characterising the stability of both stationary and travelling wave solutions, under the assumption that the firing rate function is the Heaviside step. We find that these differences in timing for the two populations can cause instabilities of these solutions, leading to, for example, stationary breathers. We also analyse "anti-pulses", a novel type of pattern for which all but a small interval of the domain (in moving coordinates) is active. These results extend previous work on neural fields with space-dependent delays, and demonstrate the importance of considering the effects of the different time-courses of excitatory and inhibitory neural activity.     

Exercise training reduces myocardial lipid peroxidation following short-term ischemia-reperfusion

PURPOSE: The purpose of these experiments was to test the hypothesis that endurance exercise training will reduce myocardial lipid peroxidation following short-term ischemia and reperfusion (I-R). METHODS: Female Sprague-Dawley rats (4 months old) were randomly assigned to either a sedentary control group (N = 13) or to an exercise training group (N = 13). The exercise trained animals ran 4 d.wk-1 (90 min.d-1) at approximately 75% V02max. Following a 10-wk training program, animals were anesthetized, mechanically ventilated, and the chest was opened by thoracotomy. Coronary occlusion was achieved by a ligature around the left coronary artery; occlusion was maintained for 5 min followed by a 10-min period of reperfusion. RESULTS: Although training did not alter (P > 0.05) myocardial activities of antioxidant enzymes (superoxide dismutase and glutathione peroxidase), training was associated with significant increase (P > 0.05) in heat shock protein (HSP72) in the left ventricle. Compared with controls, trained animals exhibited significantly lower levels (P < 0.05) of myocardial lipid peroxidation following I-R. CONCLUSION: These data support the hypothesis that exercise training provides protection against myocardial lipid peroxidation induced by short-term I-R in vivo.     

The effect of selection of time steps and average assumptions on the continuous simulation of rainwater harvesting strategies.

The use of domestic rainwater tanks with back up from mains water supplies in urban areas can produce considerable reductions in mains water demands and stormwater runoff. It is commonplace to analyse the performance of rainwater tanks using continuous simulation with daily time steps and average water use assumptions. This paper compares this simplistic analysis to more detailed analysis that employs 6 minute time steps and climate dependent water demand. The use of daily time steps produced considerable under-estimation of annual rainwater yields that were dependent on tank size, rain depth, seasonal distribution of rainfall, water demand and tank configuration. It is shown that analysis of the performance of rainwater tanks is critically dependent on detailed inputs.     

The control of protein release from poly(DL-lactide co-glycolide) microparticles by variation of the external aqueous phase surfactant in the water-in oil-in water method

A unique feature of p21 that distinguishes it from the other cyclin-dependent kinase (CDK) inhibitors is its ability to associate with the proliferating cell nuclear antigen (PCNA), an auxiliary factor for DNA polymerases delta and epsilon. While it is now well established that inhibition of cyclin/CDK complexes by p21 can result in G1 cell cycle arrest, the consequences of p21/PCNA interaction on cell cycle progression have not yet been determined. Here, we show, using a tetracycline-regulated system, that expression of wild-type p21 in p53-deficient DLD1 human colon cancer cells inhibits DNA synthesis and causes G1 and G2 cell cycle arrest. Similar effects are observed in cells expressing p21CDK-, a mutant impaired in the interaction with CDKs, but not in cells expressing p21PCNA-, a mutant deficient for the interaction with PCNA. Analysis of cells treated with a p21-derived PCNA-binding peptide provides additional evidence that the growth inhibitory effects of p21 and p21CDK result from their ability to bind to PCNA. Our results suggest that p21 might inhibit cell cycle progression by two independent mechanisms, inhibition of cyclin/CDK complexes, and inhibition of PCNA function resulting in both G1 and G2 arrest.     

Biomechanical and physiological comparison of conventional webbing and the M83 assault vest

This study compared the effect of load distribution using two different webbing designs on oxygen consumption and running kinematics of soldiers. It was hypothesised that running with webbing that distributes the load closer to the body (M83 Assault Vest) would expend less energy compared to running with conventional webbing (CON). Seven soldiers randomly completed three treadmill trials; an unloaded VO(2)max test, and two loaded (8 kg) efficiency tests using either the M83 or CON webbing. The VO(2)max test and the loaded efficiency tests had 4-min stages at 5, 8, 10 and 12 km h(-1). Energy expenditure was measured via indirect calorimetry and video analysis was used to determine stride frequency (SF) and stride length (SL) during each trial. Participants using the M83 webbing expended significantly (p<0.05) less energy at all four running velocities compared to the CON trials. The M83 webbing resulted in smaller changes to SL and SF from the unloaded trial when compared to the CON trial. These results indicate that the M83 vest that is designed to distribute the load closer to the body may have an energy efficiency advantage over conventional webbing when soldiers are running.     

Preparation of 2,5‐Diamino‐3,6‐Dinitropyrazine (ANPZ‐i): A Novel Candidate High Energy Insensitive Explosive

2,5‐Diamino‐3,6‐dinitropyrazine (ANPZ‐i) has been prepared via the electrophilic nitration of 2,5‐diethoxypyrazine using nitronium tetrafluoroborate in sulpholane and subsequent amination under autoclave conditions. Molecular modelling studies have been carried out which indicate that ANPZ‐i should have a similar performance to RDX but with an expected higher insensitivity. ANPZ‐i ( 1 ) is therefore a novel candidate high energy insensitive explosive.     

On the relationship between gap edge and specific heat of a superconductor

We critically examine three empirical procedures that have been proposed and used in the literature to extract, from electronic specific heat curves in the superconducting state, a value for the zero temperature energy gap. We do this by calculating, from Eliashberg theory, the electronic specific heat for many superconductors for which the electron-phonon spectral densities are known. Model spectral densities are also considered so as to test, in more extreme cases, the proposed procedures. We conclude that only one case, a modification of an empirical method, yields quantitatively reliable results.