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The anterior thigh muscles are particularly susceptible to muscle loss and weakness during ageing, although how this is associated with changes to neuromuscular structure and function in terms of motor unit (MU) number, size and MU potential (MUP) stability remains unclear. Intramuscular (I.M.) and surface electromyographic signals were recorded from the vastus lateralis (VL) during voluntary contractions held at 25% maximal knee extensor strength in 22 young (mean ± SD, 25.3 ± 4.8 years) and 20 physically active older men (71.4 ± 6.2 years). MUP size, firing rates, phases, turns and near fibre (NF) jiggle were determined and MU number estimates (MUNEs) were made by comparing average surface MUP with maximal electrically‐evoked compound muscle action potentials. Quadriceps cross‐sectional area was measured by magnetic resonance imaging. In total, 379 individual MUs were sampled in younger men and 346 in older men. Compared to the MU in younger participants, those in older participants had 8% lower firing rates and larger MUP size (+25%), as well as increased complexity, as indicated by phases (+13%), turns (+20%) and NF jiggle (+11%) (all P < 0.0005). The MUNE values (derived from the area of muscle in range of the surface‐electrode) in older participants were ∼70% of those in the young (P < 0.05). Taking into consideration the 30% smaller cross‐sectional area of the VL, the total number of MUs in the older muscles was between 50% and 60% lower compared to in young muscles (P < 0.0005). A large portion of the VL MU pool is lost in older men and those recruited during moderate intensity contractions were enlarged and less stable. These MU changes were evident before clinically relevant changes to muscle function were apparent; nevertheless, the changes in MU number and size are probably a prelude to future movement problems.

This paper examines the addition of design margins for building services energy infrastructure during the design process. It argues that care must be taken when applying margins; ensuring cumulative effects do not undermine the ability of systems to be energy efficient. An example of a hospital Trust is provided showing the addition of design margins impacting the energy efficiency of services provided. Tensions are found between delivery of flexibility, adaptability and other change parameters and the need for the system to be bounded, so as to encourage effectiveness.

Climate change could have dramatic consequences for the earth's environment, especially its hydrology, yet the ‘noise’ of natural climate variability can mask the impacts of climate change on shorter time scales, and can act (in an unpredictable way) to enhance or reduce its effect in any given period in the future. Thus, impact studies based on time slices, which look at modelled differences between baseline (e.g. 1961–1990) and future (e.g. 2070–2099) periods, can be misleading. This paper makes use of three new transient climate projections, from a perturbed parameter ensemble of a regional climate model (RCM) covering the period 1950–2099, to investigate transient changes in flood frequency and timing for two example catchments in England. Annual maximum (AM) time series are extracted from modelled flow timeseries (for hourly, daily mean and running 30-day mean flows). The AM series are analysed in terms of flood frequency (using a fitted generalised logistic distribution) and timing in a 30-year moving window. A non-linear trend analysis is performed on the derived time series, with permutation testing to estimate statistical significance. The results show that changes over the period are often non-linear, and vary considerably in size and statistical significance according to catchment, flow time step and RCM ensemble member. The relative effects of the three RCM ensemble members are consistent with their relative climate sensitivities. A nationwide analysis, using daily mean flows from a grid-based runoff and routing model for the UK with one of the RCM ensemble members, was consistent with the catchment results in terms of direction of trends, but generally gave trends of a higher magnitude, indicating the presence of some hydrological model structure uncertainty. The nationwide results suggest increased flood risk across much of the country.

If myonuclear loss initiates muscle wasting, it should precede the loss of muscle mass. As aging affects muscle plasticity, the time-course of muscle atrophy during disuse may differ between young and old animals. To investigate this, gastrocnemius muscles of 5- and 25-month-old rats were exposed to 1, 2, or 4 weeks of denervation, whereas the contralateral gastrocnemius muscles served as controls. Muscle fibers of each type responded similarly to 4 weeks of denervation. For both ages most of the atrophy (36%; P < 0.001) occurred in the first 2 weeks. In young-adult muscles, the myonuclear number remained constant, but in old muscles it decreased to below control level after 4 weeks of denervation (P < 0.05). Despite this differential response, myonuclear domain size decreased similarly at both ages (P < 0.001). In both young-adult and old rats, denervation-induced atrophy was not preceded by a loss of myonuclei. © 2011 Wiley Periodicals, Inc.

The design of hydraulic structures requires knowledge of how much rain is likely to fall within a certain amount of time, and over a specific area. Point rainfalls are only representative for a very limited area, and for larger areas the areal average rainfall depth is likely to be much smaller than at the point of maximum observed depth. The estimation of areal reduction factors is concerned with the relationship between the point and areal rainfalls. This relationship has been found to vary with, for example, predominant weather type, season and return period. Methods for estimation of areal reduction factors include empirical and analytical methods. The current design guidelines in the United Kingdom are based on an empirical method, but since they were issued in 1975, several new analytical methods have been proposed. These methods are discussed, and recommendations for an update suitable for United Kingdom conditions are made.

To explore the cause of higher skeletal muscle fatigue resistance in women than men, we used electrically evoked contractions (1 s on, 1 s off, 30 Hz, 2 min), which circumvent motivational bias and allow examination of contractile properties. We compared 29 men [26.5 (7.0) years old; mean (s.d.)] with 35 women [25.4 (7.6) years old]. Strength of the quadriceps muscle was higher in men than women (P < 0.001). The lower maximal rate of relaxation in women (P = 0.002) indicates that their muscles were slower than those of men. The torque declined less in women than in men [37.7 (10.7) versus 29.9 (10.0)%; P = 0.002], and was not related to muscle strength or size, as determined with magnetic resonance imaging. The sex difference in fatigability was also seen when the circulation to the leg was occluded [torque declined 76.9 (10.8) versus 59.5 (16.9)% in men versus women, respectively; P = 0.008]. The maximal rate of relaxation correlated with the fatigability of the muscle under all conditions (correlations ranging from 0.34 to 0.51, P < 0.02). We conclude that the sex-related difference in skeletal muscle fatigue resistance is not explicable by differences in motivation, muscle size, oxidative capacity and/or blood flow between sexes, but might be related to differences in fibre type composition. © 2008 The Authors.

Slow relaxation from an isometric contraction is characteristic of acutely fatigued muscle and is associated with a decrease in the maximum velocity of unloaded shortening (V

We have investigated the action of exogenous nitric oxide (NO) on the strength and contractile properties of human skeletal muscle working in vivo. Maximum isometric voluntary contraction force (MVC) of the quadriceps was measured and superimposed electrical stimulation was used to estimate the level of activation and 'true maximum force' (TMF). Force-frequency relationships were determined to assess changes in contractile properties of the muscle. Subjects in the experimental group (E, n = 10) were measured before and during two separate periods of treatment with different doses of glyceryl trinitrate, a NO donor, delivering 100 (GTN100) or 200 (GTN200) μg h

Trypsin-like enzyme activity of the larvae of two planktonic predatory crustaceans, Homarus gammarus and Nephrops norvegicus (Decapoda: Nephropidae) and the omnivorous larvae of Carcinus maenas (Decapoda: Brachyura) were investigated at each larval stage until metamorphosis. Two copepods, herbivorous or omnivorous grazers, Centropages typicus and Temora longicornis (Copepoda: Calanoidae) were also investigated for this enzyme. A comparison of trypsin-like activity in these and other decapod larvae shows a pattern with high levels in herbivores, low levels in carnivores and intermediate levels in omnivores. Herbivorous planktonic crustaceans appear to rely on high digestive enzyme activities to extract nutrients from less digestible algae or particulates, whereas carnivorous larvae have limited enzymatic capacity as they feed at higher trophic levels upon large and easily digestible prey. Omnivorous Carcinus maenas larvae have intermediate levels of digestive enzymes and are able to transfer between herbivorous and omnivorous feeding. We wish to thank Dr D.J. Fletcher, Mr C. Zeng and Sea Zoo, Anglesey (UK) for providing lobster and crab larvae for the present investigations. The first author greatly acknowledges (^ukurova University (Turkey) and Overseas Research Scheme (UK) for providing grants to support this study. Special thanks also to B. Roberts and G. Hughes for their technical assistance during these experiments.

Microalgae play an important role in conditioning water quality for penaeid larval culture. Recently it has been demonstrated that a modification of the green water larval culture system (Ling, 1969) for Macrobrachium allows the production of post larvae without any water change, despite extensive use of artificial feeds (Ang and Cheah, 1986). Increase of toxic metabolites such as ammonia and nitride are also common in penaeid larval culture, especially where excessive amounts of artifial feeds are employed. Present work examines the use of six marine microalgae at four cell concentrations as a "biological filter" system, to control and detoxify levels of ammonia and nitrite in P. monodon larval culture water whilst using artificial diet. Preliminary results indicate that amongst the six algal species tested, C. japonica at 1000 cell μlˉ¹ was most effective in reducing accumulated toxic metabolites from an unchanged culture water environment.