These data demonstrate that lower extremity resistance exercise can improve muscle structure and function in those with limited exercise tolerance. The greater strength increase following negative work training resulted in improved balance, stair descent, and fall risk only in the ECC group. Because low energy cost is coupled to high force production with eccentric exercise, this intervention may be useful for a number of patients that are otherwise unable to achieve high muscle forces with traditional resistance exercise.

No abstract

This study used X ray computed tomography (CT) to investigate the variability in the aperture field of natural fractures in two granitic cores; one core, 57 mm in diameter and 146 mm in length, was studied with a medical CT scanner, whereas the other core, 87 mm in diameter and 245 mm long, was characterized by means of an industrial CT scanner. A quantitative methodology for measuring the fracture‐aperture thickness from CT images was developed and applied to images of cores to reconstruct the distribution of fracture aperture in the cores, with a spatial resolution of 1.4 mm by 1.4 mm by 5 mm. The CT images of the natural fractures revealed that the aperture thickness (1) is not constant within the fracture plane, (2) varies over several orders of magnitude, and (3) approximately followed a lognormal distribution for one of the cores. The CT method, when applied to monitor the movement of contrast agents injected into the cores, demonstrated fingering of the flow. Higher contrast agent concentrations and earlier contrast agent arrivals correlated with larger aperture regions of the core. The results of this study demonstrate that CT can be used to characterize fractures nondestructively and to detect the movement of contrast agents in granitic cores.

During voluntary contraction, firing rates of individual motor units (MUs) increase modestly over a narrow force range beyond which little additional increase in firing rate is seen. Such saturation of MU discharge may be a consequence of extrinsic factors that limit net synaptic excitation acting on motor neurons (MNs) or may be due to intrinsic properties of the MNs. Two sets of experiments involving recording of human biceps brachii MUs were carried out to evaluate saturation. In the first set, the extent of saturation was quantified for 136 low-threshold MUs during isometric ramp contractions. Firing rate-force data were best fit by a saturating function for 90% of MUs recorded with a maximum rate of 14.8 ± 2.0 impulses/s. In the second set of experiments, to distinguish extrinsic from intrinsic factors underlying saturation, we artificially augmented descending excitatory drive to biceps MNs by activation of muscle spindle afferents through tendon vibration. We examined the change in firing rate caused by tendon vibration in 96 MUs that were voluntarily activated at rates below and at saturation. Vibration had little effect on the discharge of MUs that were firing at saturation frequencies but strongly increased firing rates of the same units when active at lower frequencies. These results indicate that saturation is likely caused by intrinsic mechanisms that prevent further increases in firing rate in the presence of increasing synaptic excitation. Possible intrinsic cellular mechanisms that limit firing rates of motor units during voluntary effort are discussed.

Research on public support for war shows that citizens are responsive to various aspects of strategic context. Less attention has been paid to the core characteristics of the target state. In this comparative study we report survey experiments manipulating two such characteristics, regime type and dominant faith, to test whether the ''democratic peace'' and the ''clash of civilizations'' theses are reflected in U.S. and British public opinion. The basic findings show small differences across the two cases: both publics were somewhat more inclined to use force against dictatorships than against democracies and against Islamic than against Christian countries. Respondent religion played no moderating role in Britain: Christians and nonbelievers were alike readier to attack Islamic states. However, in the United States, the dominant faith effect was driven entirely by Christians. Together, our results imply that public judgments are driven as much by images and identities as by strategic calculations of threat.

No abstract

When considering elections in multi-level contexts, scholars have typically assumed-in line with second-order election theory-that the way voters approach an election depends on their attributions of responsibility, that is, on what they see as being at stake in that election. This assumption is questionable. The formal position is not always clear, and is further blurred by parties and the media. Moreover, many voters pay little attention to politics and have little incentive to trace constitutional responsibilities. In this paper I use data from election studies in two multi-level contexts, Ontario and Scotland, to explore the nature and impact of voters' attributions of responsibility. The evidence suggests that, when called upon in surveys to do so, many voters can confidently and fairly accurately assign issues to different levels of government. Yet they do not seem to consider these attributions much at elections. There is very little indication that issues weighed heavier in the decision-making of those who regarded them as the responsibility of that electoral arena. A plausible explanation is that most voters sidestep the cognitive demands imposed by multi-level elections.

This article reports on an audience costs experiment embedded into a survey of the British public (N = 2235). We extend previous research into audience costs in three main directions. First, we provide clear and direct evidence that they exist for a second-order democratic power, the United Kingdom. Second, we show that the extent of audience costs varies, and at times substantially, along with features of the crisis situation that have not been examined empirically in this context before. In particular, the type of crisis strongly influences public reactions both to bluffing in general and to the wisdom or otherwise of escalating crises before backing down. While audience costs do appear to exist for a UK Prime Minister, he or she cannot inflate them by moving up the escalation chain. Rather, a limited use of force tends to mitigate these costs among the British public because it appears to them a more consistent strategy. Third, we show that public disapproval of a failed bluffing strategy is stronger among the more politically engaged, increasing the likelihood that audience costs will be paid at the ballot box.