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Plant-soil feedbacks (PSFs) describe the effect of a plant species on soil properties, which affect the performance of future generations. Here we test the hypothesis that drought alters PSFs by reducing plant-microbe associations and nutrient uptake. We chose two grassland forb species, previously shown to respond differently to soil conditioning and drought, to test our hypothesis. We conditioned unsterilised grassland soil with one generation of each species, and left a third soil unconditioned. We grew a second generation consisting of each combination of plant species, soil, and drought in a full factorial design, and measured soil microbial community and nutrient availability. Scabiosa columbaria displayed negative PSF (smaller plants) under non-droughted conditions, but neutral under drought, suggesting that drought disrupts plant-soil interactions and can advantage the plant. Photosynthetic efficiency of S. columbaria was reduced under drought, but recovered on rewetting regardless of soil conditioning, indicating that PSFs do not impede resilience of this species. Sanguisorba minor showed positive PSFs (larger plants), probably due to an increase in soil N in conspecific soil, but neutral PSF under drought. PSF neutralisation appeared to occur through drought-induced change in the soil microbial community for this species. When S. minor was planted in conspecific soil, photosynthetic efficiency declined to almost zero, with no recovery following rewetting. We attributed this to increased demand for water through higher demand for nutrients with positive PSF. Here we show that drought neutralises PSFs of two grassland forbs, which could have implications for plant communities under climate change. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate two features of a new rotating needle driver in a domestic swine model: (1) a quick release safety mechanism and (2) the impact of spinning the needle on the force profile. The experiments were conducted in a multi-modality interventional suite. An initial CT scan was obtained to determine the location of the target, in the liver or lung. The robotic arm was positioned directly over the marked skin entry point. Control parameters were set to rotation speeds of 0, 90, or 180 rpm. The breakaway force magnitude was also preset to a predetermined force. The physician used the joystick to drive the needle towards the target while the system recorded needle insertion depth and forces. Sixteen insertions were completed (14 in liver and 2 in lung) and 12 released the needle upon the desired set force. The mean response time of the quick release mechanism was 202 ± 39 ms. Needle rotation resulted in reduced insertion force. The robot-assisted needle insertion system was shown to be functional in a multimodality imaging clinical environment on a swine model. The system has potential future applications in precision minimally invasive procedures including biopsy and radiofrequency ablation. [ABSTRACT FROM AUTHOR]

Abstract Rationale: A substantial portion of cigarette smokers prefer menthol-flavored cigarettes. To date, however, no studies have examined whether menthol in cigarettes has central pharmacological effects. Objective: We investigated psychophysiological and subjective effects of smoking menthol versus non-menthol cigarettes in both menthol and non-menthol smokers. To assess these effects independently of the immediate effects of nicotine, all cigarettes employed were "denicotinized" (FTC nicotine yield = 0.06 mg). Methods: The psychophysiological measures were EEG and heart rate (HR). The subjective measures assessed mental alertness, muscular relaxation, anxiety/nervousness, and how much a participant wanted to smoke one of his usual brand of cigarettes. Menthol and non-menthol smokers participated in a single session in which each participant smoked both a menthol and a non-menthol denicotinized cigarette (order balanced across participants). The psychophysiological and subjective measures were recorded before and after smoking each cigarette. Results: Out of 48 F-ratios spanning 22 analyses of variance involving the critical interaction between pre-/post-smoking and menthol/non-menthol cigarette, only one unambiguously fit a "pharmacological" pattern, a result indistinguishable from a type-I statistical error. We report evidence that menthol smokers may be chronically less aroused and more sensitive to the effects of nicotine than non-menthol smokers. Conclusions: We found little evidence that menthol in cigarettes has central pharmacological effects. [ABSTRACT FROM AUTHOR]

This paper provides an assessment of our current understanding of the hole-pressure effect and the role it plays in the field of viscometry. The discovery in 1968 by Broadbent, Kaye, Lodge and Vale that the use of pressure taps to measure the normal stress exerted on a boundary by a non-Newtonian material can lead to significant errors has opened up interesting new avenues for making viscometric measurements. The kinematical theory developed by Higashitani and Pritchard (1972) to estimate the hole pressure, to which a deeper understanding has recently been supplied by Yao and Malkus (1990), has formed the basis of many new developments in viscometry. It is interesting that such a simplistic theory for the hole pressure apparently has a rather wide range of applicability. [ABSTRACT FROM AUTHOR]

Several of the known scaling laws in the animal kingdom are based on a so-called allometric correlation in which some physical quantity is presumed to scale as some power of the mass of the animal. Such a simple correlation, when deduced purely as an empirical result, often hides the physical balances that fix the relevant scaling law. In particular, the emphasis on a simple allometric scaling has often masked the fundamental role played by time scales associated with the physical balances being struck. In this paper I have concentrated on three different attributes to which the use of dimensional analysis, scaling arguments and some judicious guesswork have led to new results and an understanding of some balances that occur in the animal kingdom. The running speed of animals is examined and a rationale deduced for the resolution of a conundrum first posed by A.V. Hill of why it is that many animals appear to have approximately the same maximum speed. A complete dimensional analysis for scaling the basal metabolic rate for a class of animals suggests that a detailed understanding of the physical balances that fix the metabolic rate could be quite subtle. However, the use of such an analysis has led to the discovery of a new correlation for mammals, relating the metabolic rate to the mass and the pulse rate of the animal. At the heart of many scaling laws for animal motion is the provision of an estimate of how the skeletal structure depends on the mass of the animal. It has been known for some time that the assumption of isometry between the builds of animals is too constrictive to describe the observed scaling laws. It is shown here how to relax the isometric assumption and deduce scaling laws in good agreement with observation. Thus, it appears that the skeletal dimensions of many animals with exoskeletons are fixed by the need to support static rather than dynamical loads. The scaling laws associated with endoskeletons are more complex, apparently, though the analysis does suggest that it is dynamical loading which is decisive for the skeletal design of land mammals. [ABSTRACT FROM AUTHOR]

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The Gaussian surrogate-date procedure was applied to the measurement of the effect of cigarette smoking on the dimensional complexity of normal, resting EEG. Evidence of significant nonlinearity in the EEG was obtained, replicating previous results. However, unlike EEG dimensional complexity, EEG nonlinearity (difference between original and surrogate data) was not affected by smoking. This indicates that, under resting conditions, smoking/nicotine may have a modulating effect on input from the reticular activating system, with such input having a global, linearizing effect on cortical dynamics. Nonlinear dynamics resulting from intracortical processes appear not to be affected. [ABSTRACT FROM AUTHOR]