2,824 research outputs found

    Plastic dilation rate characteristic of concrete confined with steel tube

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    The use of external confining devices to confine concrete has become widely used. One of the purposes is to gain additional concrete strength and ductility. Although there are many types of external confining devices, in this paper, the attention is limited to the use ofthe steel tube as anexternal confining device. One of the main objectives ofthis research is to study the plastic dilation rate behavior of concrete-filled-steel-tube (CFST) columns. The experimental data for the plastic dilation rate is extracted, and compared with the authors concrete plasticity model. In the authors’ previous research, the calibration of the plastic dilation rate model was based on confined concrete tested under both active and passive confinement using FRP wraps. Since the behavior of the steel tube and the FRP materials are different, the author’s plastic dilation rate model needs to be re-evaluated for CFST columns. Comparisons of the extracted experimental plastic dilation rates with the model prediction for CFST specimens with normal strength concrete show good agreement and requires no adjustment in the formulation. However, for a specimen with 80 MPa concrete, the proposed formulation showsslightly lowerplastic dilation rates.More experimental data for CFST using high strength concretes is required for further investigation. For the sake of completeness, the overall response of two CFST specimensisalso evaluated using anin-house three-dimensional non-linear finite element analysis (3D-NLFEA) using the author’s proposed plasticity formulation for confined concrete

    Compliance with protocols in dental conditions

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    The aims of this study were to assess compliance with the developed treatment protocols through the dissemination of case studies. Out of 203 questionnaires distributed, 125 (62%) were collected. Community pharmacists were asked to complete case studies within a fortnight to indicate their line of action in three conditions presented. Average percentage compliance with the protocols was 73%.peer-reviewe

    Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat: an eddy covariance study

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    Coralline algal (maerl) beds are widespread, slow-growing, structurally complex perennial habitats that support high biodiversity, yet are significantly understudied compared to seagrass beds or kelp forests. We present the first eddy covariance (EC) study on a live maerl bed, assessing the community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (~20 m distant) permeable sandy habitat. The O2 exchange rate was highly dynamic, driven by light availability and the ambient tidally-driven flow velocity. Linear relationships between the EC O2 fluxes and available light indicate that the benthic phototrophic communities were lightlimited. Compensation irradiance (Ec) varied seasonally and was typically ~1.8-fold lower at the maerl bed compared to the sand. Substantial GPP was evident at both sites; however, the maerl bed and the sand habitat were net heterotrophic during each sampling campaign. Additional inputs of ~4 and ~7 mol m-2 yr-1 of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m2 benthic chambers during nighttime revealed O2 uptake rates that varied by up to ~8-fold between replicate chambers (from -0.4 to -3.0 mmol O2 m-2 h-1; n = 4). However, despite extensive O2 flux variability on meter horizontal scales, mean rates of O2 uptake as resolved in parallel by chambers and EC were typically within 20% of one another

    Latency-Based and Psychophysiological Measures of Sexual Interest Show Convergent and Concurrent Validity.

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    Latency-based measures of sexual interest require additional evidence of validity, as do newer pupil dilation approaches. A total of 102 community men completed six latency-based measures of sexual interest. Pupillary responses were recorded during three of these tasks and in an additional task where no participant response was required. For adult stimuli, there was a high degree of intercorrelation between measures, suggesting that tasks may be measuring the same underlying construct (convergent validity). In addition to being correlated with one another, measures also predicted participants' self-reported sexual interest, demonstrating concurrent validity (i.e., the ability of a task to predict a more validated, simultaneously recorded, measure). Latency-based and pupillometric approaches also showed preliminary evidence of concurrent validity in predicting both self-reported interest in child molestation and viewing pornographic material containing children. Taken together, the study findings build on the evidence base for the validity of latency-based and pupillometric measures of sexual interest

    Electrostatic image effects for counter-ions between charged planar walls

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    We study the effect of dielectric inhomogeneities on the interaction between two planparallel charged surfaces with oppositely charged mobile charges in between. The dielectric constant between the surfaces is assumed to be different from the dielectric constant of the two semiinfinite regions bounded by the surfaces, giving rise to electrostatic image interactions. We show that on the weak coupling level the image charge effects are generally small, making their mark only in the second order fluctuation term. However, in the strong coupling limit, the image effects are large and fundamental. They modify the interactions between the two surfaces in an essential way. Our calculations are particularly useful in the regime of parameters where computer simulations would be difficult and extremely time consuming due to the complicated nature of the long range image potentials.Comment: 21 pages, 8 figure

    Comparison of minimally invasive parathyroidectomy under local anaesthesia and minimally invasive video-assisted parathyroidectomy for primary hyperparathyroidism: A cost analysis

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    Background: Primary hyperparathyroidism (PHPT) origins from a solitary adenoma in 70-95% of cases. Moreover, the advances in methods for localizing an abnormal parathyroid gland made minimally invasive techniques more prominent. This study presents a micro-cost analysis of two parathyroidectomy techniques. Patients and methods: 72 consecutive patients who underwent minimally invasive parathyroidectomy, video-assisted (MIVAP, group A, 52 patients) or "open" under local anaesthesia (OMIP, group B, 20 patients) for PHPT were reviewed. Operating room, consumable, anaesthesia, maintenance costs, equipment depreciation and surgeons/anaesthesiologists fees were evaluated. The patient's satisfaction and the rate of conversion to conventional parathyroidectomy were investigated. T-Student's, Kolmogorov-Smirnov tests and Odds Ratio were used for statistical analysis. Results: 1 patient of the group A and 2 of the group B were excluded from the cost analysis because of the conversion to the conventional technique. Concerning the remnant patients, the overall average costs were: for Operative Room, 1186,69 \u20ac for the MIVAP group (51 patients) and 836,11 \u20ac for the OMIP group (p<0,001); for the Team, 122,93 \u20ac (group A) and 90,02 \u20ac (group B) (p<0,001); the other operative costs were 1388,32 \u20ac (group A) and 928,23 \u20ac (group B) (p<0,001). The patient's satisfaction was very strongly in favour of the group B (Odds Ratio 20,5 with a 95% confidence interval). Conclusions: MIVAP is more expensive compared to the "open" parathyroidectomy under local anaesthesia due to the costs of general anaesthesia and the longer operative time. Moreover, the patients generally prefer the local anaesthesia. Nevertheless, the rate of conversion to the conventional parathyroidectomy was relevant in the group of the local anaesthesia compared to the MIVAP, since the latter allows a four-gland exploration

    Health and the Economy : a statement of concern

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    The relationship between health and the economy is an intimate and complex one. The economy of health and the apportioning of funds to different medical services and health care programs are issues that depend on the health profile of a given community as well as the expectations of its members. Decisions ultimately depend on available resources and political priorities. Health and the economy cannot be isolated and contrasted, as the integrity of a given economic system clearly depends on the state of health of the community both at an individual level as well as at a population level.peer-reviewe

    Description beyond the mean field approximation of an electrolyte confined between two planar metallic electrodes

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    We study an electrolyte confined in a slab of width WW composed of two grounded metallic parallel electrodes. We develop a description of this system in a low coupling regime beyond the mean field (Poisson--Boltzmann) approximation. There are two ways to model the metallic boundaries: as ideal conductors in which the electric potential is zero and it does not fluctuate, or as good conductors in which the average electric potential is zero but the thermal fluctuations of the potential are not zero. This latter model is more realistic. For the ideal conductor model we find that the disjoining pressure is positive behaves as 1/W31/W^3 for large separations with a prefactor that is universal, i.e. independent of the microscopic constitution of the system. For the good conductor boundaries the disjoining pressure is negative and it has an exponential decay for large WW. We also compute the density and electric potential profiles inside the electrolyte. These are the same in both models. If the electrolyte is charge asymmetric we find that the system is not locally neutral and that a non-zero potential difference builds up between any electrode and the interior of the system although both electrodes are grounded.Comment: 16 pages, 5 figures, added a new appendix B and a discussion on ideal conductors vs. good conductor
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