Cost evaluation of cardiac magnetic resonance imaging versus coronary angiography for the work-up of coronary artery disease

Background: CMR has recently emerged as a robust and reliable technique to assess coronary artery disease (CAD). A negative perfusion CMR test predicts low event rates of 0.3-0.5%/year. Invasive coronary angiography (CA) remains the "gold standard" for the evaluation of CAD in many countries.Objective: Assessing the costs of the two strategies in the European CMR registry for the work-up of known or suspected CAD from a health care payer perspective. Strategy 1) a CA to all patients or 2) a CA only to patients who are diagnosed positive for ischemia in a prior CMR.Method and results: Using data of the European CMR registry (20 hospitals, 11'040 consecutive patients) we calculated the proportion of patients who were diagnosed positive (20.6%), uncertain (6.5%), and negative (72.9%) after the CMR test in patients with known or suspected CAD (n=2'717). No other medical test was performed to patients who were negative for ischemia. Positive diagnosed patients had a coronary angiography. Those with uncertain diagnosis had additional tests (84.7%: stress echocardiography, 13.1%: CCT, 2.3% SPECT), these costs were added to the CMR strategy costs. Information from costs for tests in Germany and Switzerland were used. A sensibility analysis was performed for inpatient CA. For costs see figure. Results - costs.Discussion: The CMR strategy costs less than the CA strategy for the health insurance systems both, in Germany and Switzerland. While lower in costs, the CMR strategy is a non-invasive one, does not expose to radiation, and yields additional information on cardiac function, viability, valves, and great vessels. Developing the use of CMR instead of CA might imply some reduction in costs together with superior patient safety and comfort, and a better utilization of resources at the hospital level. Document introduit le : 01.12.2011

Accounting conservatism and firm investment efficiency

Conservatism, through the timelier recognition of losses in the income statement, is expected to increase firm investment efficiency through three main channels: (1) by decreasing the adverse effect of information asymmetries between outside equity holders and managers, facilitating the monitoring of managerial investment decisions; (2) by increasing managerial incentives to abandon poorly performing projects earlier and to undertake fewer negative net present-value investments; and (3) by facilitating the access to external financing at lower cost. Using a large US sample for the period 1990-2007 we find a negative association between conservatism and measures of over- and under- investment, and a positive association between conservatism and future profitability. This is consistent with firms reporting more conservative numbers investing more efficiently and in more profitable projects. Our results add to a growing stream of literature suggesting that eliminating conservatism from accounting regulatory frameworks may lead to undesirable economic consequences.

The Complementarity between segment disclosure and earnings quality, and its effect on cost of capital

We investigate the role of earnings quality in determining the levels of segment disclosure, and whether and how better quality earnings and segment disclosure influences cost of capital. Using a large US sample for the period 2001-2006, we find a positive relation between earnings quality and levels of segment disclosures. We also find that firms providing better quality segment information, contingent upon good earnings quality, enjoy lower cost of capital. We base our empirical tests on a self created index of segment disclosure. Our results contribute to a better understanding of (1) the incentives for providing segment disclosures, and (2) how accounting quality (quality of segment information and earnings quality) is related to the cost of capital.

Anesthésie locale par tumescence [Tumescent local anesthesia].

Tumescent anesthesia is a local anesthesia produced by the infiltration of a large volume of very dilute anesthetic solution into the subcutaneous tissue. Many surgical procedures (liposuction, facelift, varicose vein surgery, etc.), which were previously performed under general or locoregional anesthesia, can now be achieved with local tumescent anesthesia. This type of anesthesia has many advantages: reduction of both anesthetic risks and surgical complications (bleeding, hematoma), prolonged anesthesia reducing the need for postoperative analgesia, and costs reduction because all these surgical procedures can be performed on an outpatient basis.

Local heating of human skin causes hyperemia without mediation by muscarinic cholinergic receptors or prostanoids.

RESUME Les changements locaux de la température à la surface de la peau humaine ont une influence importante sur sa perfusion. La chaleur augmente localement le flux sanguin cutané, mais les mécanismes et les médiateurs de cette réponse (réponse thermique d'hyperémie) sont incomplètement élucidés. Dans la présente étude, nous avons examiné la relation possible entre la réponse thermique d'hyperémie, les récepteurs cholinergiques muscariniques et la production des prostaglandines vasodilatatrices. Chez 13 sujets de sexe masculin en bonne santé âgés entre 20 et 30 ans, une chambre métallique (contenant de l'eau) dont la température peut être contrôlée, a été placée sur la face palmaire de leur avant-bras et utilisée pour augmenter la température de surface de 34 à 41°C. L'hyperémie cutanée consécutive a été enregistrée par l'intermédiaire d'un scanner laser-Doppler. Dans une expérience, chacun des 8 sujets a reçu un bolus i.v. de glycopyrolate (agent antimuscarinique) (4 µg/kg) lors d'une visite et de NaCl 0,9% lors de l'autre visite. La réponse thermique d'hyperémie a été déterminée dans l'heure suivant les injections. Les glycopyrolate a efficacement empêché la vasodilation des micro-vaisseaux cutanés induite par iontophorèse d'acétylcholine mais n'a pas influencé la réponse thermique d'hyperémie. Dans une deuxième expérience entreprise avec 5 autres sujets 1 g d'aspirine (inhibiteur de la cyclooxygénase) administrée oralement a totalement supprimé la vasodilatation induite dans la peau par le courant anodique, sans modifier la réponse thermique d'hyperémie. La présente étude confirme l'absence de stimulation des récepteurs muscariniques et la production de prostaglandines vaso-dilatatrices dans la vasodilatation induite chez l'homme par réchauffement local de la peau de l'avant-bras. ABSTRACT Local changes in surface temperature have a powerful influence on the perfusion of human skin. Heating increases local skin blood flow (SkBF), but the mechanisms and mediators of this response (thermal hyperemia response) are incompletely elucidated. In the present study, we examined the possible dependence of the thermal hyperemia response on stimulation of muscarinic cholinergic receptors and on production of vasodilator prostanoids. In 13 male healthy subjects aged 20 - 30 years, a temperature- controlled chamber was positioned on the volar face of one forearm and used to raise surface temperature from 34to41°C. The time-course of the resulting thermal hyperemia response was recorded with a laser-Doppler imager. In one experiment, each of 8 subjects received an i.v. bolus of the antimuscarinic agent glycopyrrolate (4µg/kg) on one visit and saline on the other. The thermal hyperemia response was determined within the hour following the injections. Glycopyrrolate effectively inhibited the skin vasodilation induced by iontophoresis of acetylcholine, but did not influence the thermal hyperemia response. In a second experiment conducted in 5 other subjects, 1 gram of the cyclooxygenase inhibitor aspirin administered orally totally abolished the vasodilation induced in the skin by anodal current, but also failed to modify the thermal hyperemia response. The present study excludes the stimulation of muscarinic receptors and the production of vasodilator prostaglandins as essential and nonredundant mechanisms for the vasodilation induced by local heating in human forearm skin.

Sistema de servidores VoIP del proyecto guifi.net

Las redes inalámbricas y la VoIP están revolucionando la manera de comunicarnos debido a la fácil implementación y al bajo coste. En este proyecto se desarrolla un sistema de telefonía interna y externa para la red guifi.net que permite comunicar los servidores y los teléfonos de la red, y realizar llamadas a la red telefónica a través de un proveedor de VoIP. También se comprueban las limitaciones de la red inalámbrica y se muestran soluciones para optimizar los recursos disponibles para obtener mayor rendimiento.

An empirical analysis of a merger between a network and low-cost airlines

We use a difference-in-difference estimator to examine the effects of a merger involving three airlines. The novelty lies in the examination of this operation in two distinct scenarios: (1) on routes where two low-cost carriers and (2) on routes where a network and one of the low-cost airlines had previously been competing. We report a reduction in frequencies but no substantial effect on prices in the first scenario, while in the second we report an increase in prices but no substantial effect on frequencies. These results may be attributed to the differences in passenger types flying on these routes.

The Political cost of reforms

This paper formalizes in a fully-rational model the popular idea that politicians perceive an electoral cost in adopting costly reforms with future benefits and reconciles it with the evidence that reformist governments are not punished by voters. To do so, it proposes a model of elections where political ability is ex-ante unknown and investment in reforms is unobservable. On the one hand, elections improve accountability and allow to keep well-performing incumbents. On the other, politicians make too little reforms in an attempt to signal high ability and increase their reappointment probability. Although in a rational expectation equilibrium voters cannot be fooled and hence reelection does not depend on reforms, the strategy of underinvesting in reforms is nonetheless sustained by out-of-equilibrium beliefs. Contrary to the conventional wisdom, uncertainty makes reforms more politically viable and may, under some conditions, increase social welfare. The model is then used to study how political rewards can be set so as to maximize social welfare and the desirability of imposing a one-term limit to governments. The predictions of this theory are consistent with a number of empirical regularities on the determinants of reforms and reelection. They are also consistent with a new stylized fact documented in this paper: economic uncertainty is associated to more reforms in a panel of 20 OECD countries.

Local and global consistency properties for student placement

In the context of resource allocation on the basis of priorities, Ergin (2002) identifies a necessary and sufficient condition on the priority structure such that the student-optimal stable mechanism satisfies a consistency principle. Ergin (2002) formulates consistency as a local property based on a fixed population of agents and fixed resources -- we refer to this condition as local consistency and to his condition on the priority structure as local acyclicity. We identify a related but stronger necessary and sufficient condition (unit acyclicity) on the priority structure such that the student-optimal stable mechanism satisfies a more standard global consistency property. Next, we provide necessary and sufficient conditions for the student-optimal stable mechanism to satisfy converse consistency principles. We identify a necessary and sufficient condition (local shift-freeness) on the priority structure such that the student-optimal stable mechanism satisfies local converse consistency. Interestingly, local acyclicity implies local shift-freeness and hence the student-optimal stable mechanism more frequently satisfies local converse consistency than local consistency. Finally, in order for the student-optimal stable mechanism to be globally conversely consistent, one again has to impose unit acyclicity on the priority structure. Hence, unit acyclicity is a necessary and sufficient condition on the priority structure for the student-optimal stable mechanism to satisfy global consistency or global converse consistency.

Artificial Snow Optimization in Winter Sport Destinations Using a Multi-agent Simulation

This paper presents the Juste-Neige system for predicting the snow height on the ski runs of a resort using a multi-agent simulation software. Its aim is to facilitate snow cover management in order to i) reduce the production cost of artificial snow and to improve the profit margin for the companies managing the ski resorts; and ii) to reduce the water and energy consumption, and thus to reduce the environmental impact, by producing only the snow needed for a good skiing experience. The software provides maps with the predicted snow heights for up to 13 days. On these maps, the areas most exposed to snow erosion are highlighted. The software proceeds in three steps: i) interpolation of snow height measurements with a neural network; ii) local meteorological forecasts for every ski resort; iii) simulation of the impact caused by skiers using a multi-agent system. The software has been evaluated in the Swiss ski resort of Verbier and provides useful predictions.

Does the EU financing system contribute to shadow economic activity?

Financial contributions to the EU budget depend basically on official GDP. This means that countries with higher shadow economic activity contribute less than they should contribute in a system based on actual GDP and therefore could reduce their incentive to fight against such activities. In this paper we investigate if the EU financing system really has an influence on the intensity with which governments in EU member states fight against shadow economic activity. We find that the EU net contributors significantly fight more intensively against shadow economic activity while EU net receivers significantly fight less. As a result, shadow economic activity is higher in net receiver and lower in net contributor countries than it were in comparison with a scenario of nationally balanced EU funding. Quantitatively and averaged over the time period 2001-2007, the diagnosed effect amounts to a stimulation of hidden economic activity by almost 10% for particular economies. JEL classification: C31, D63, F33, H21, H26. Keywords: EU financing system, shadow economy, tax auditing.

How life history and demography promote or inhibit the evolution of helping behaviours.

In natural populations, dispersal tends to be limited so that individuals are in local competition with their neighbours. As a consequence, most behaviours tend to have a social component, e.g. they can be selfish, spiteful, cooperative or altruistic as usually considered in social evolutionary theory. How social behaviours translate into fitness costs and benefits depends considerably on life-history features, as well as on local demographic and ecological conditions. Over the last four decades, evolutionists have been able to explore many of the consequences of these factors for the evolution of social behaviours. In this paper, we first recall the main theoretical concepts required to understand social evolution. We then discuss how life history, demography and ecology promote or inhibit the evolution of helping behaviours, but the arguments developed for helping can be extended to essentially any social trait. The analysis suggests that, on a theoretical level, it is possible to contrast three critical benefit-to-cost ratios beyond which costly helping is selected for (three quantitative rules for the evolution of altruism). But comparison between theoretical results and empirical data has always been difficult in the literature, partly because of the perennial question of the scale at which relatedness should be measured under localized dispersal. We then provide three answers to this question.

Local-global splitting for spatiotemporal-adaptive multiscale methods

We present a novel spatiotemporal-adaptive Multiscale Finite Volume (MsFV) method, which is based on the natural idea that the global coarse-scale problem has longer characteristic time than the local fine-scale problems. As a consequence, the global problem can be solved with larger time steps than the local problems. In contrast to the pressure-transport splitting usually employed in the standard MsFV approach, we propose to start directly with a local-global splitting that allows to locally retain the original degree of coupling. This is crucial for highly non-linear systems or in the presence of physical instabilities. To obtain an accurate and efficient algorithm, we devise new adaptive criteria for global update that are based on changes of coarse-scale quantities rather than on fine-scale quantities, as it is routinely done before in the adaptive MsFV method. By means of a complexity analysis we show that the adaptive approach gives a noticeable speed-up with respect to the standard MsFV algorithm. In particular, it is efficient in case of large upscaling factors, which is important for multiphysics problems. Based on the observation that local time stepping acts as a smoother, we devise a self-correcting algorithm which incorporates the information from previous times to improve the quality of the multiscale approximation. We present results of multiphase flow simulations both for Darcy-scale and multiphysics (hybrid) problems, in which a local pore-scale description is combined with a global Darcy-like description. The novel spatiotemporal-adaptive multiscale method based on the local-global splitting is not limited to porous media flow problems, but it can be extended to any system described by a set of conservation equations.

Different approaches to modelling the cost-effectiveness of schistosomiasis control

This paper reviews three different approaches to modelling the cost-effectiveness of schistosomiasis control. Although these approaches vary in their assessment of costs, the major focus of the paper is on the evaluation of effectiveness. The first model presented is a static economic model which assesses effectiveness in terms of the proportion of cases cured. This model is important in highlighting that the optimal choice of chemotherapy regime depends critically on the level of budget constraint, the unit costs of screening and treatment, the rates of compliance with screening and chemotherapy and the prevalence of infection. The limitations of this approach is that it models the cost-effectiveness of only one cycle of treatment, and effectiveness reflects only the immediate impact of treatment. The second model presented is a prevalence-based dynamic model which links prevalence rates from one year to the next, and assesses effectiveness as the proportion of cases prevented. This model was important as it introduced the concept of measuring the long-term impact of control by using a transmission model which can assess reduction in infection through time, but is limited to assessing the impact only on the prevalence of infection. The third approach presented is a theoretical framework which describes the dynamic relationships between infection and morbidity, and which assesses effectiveness in terms of case-years prevented of infection and morbidity. The use of this model in assessing the cost-effectiveness of age-targeted treatment in controlling Schistosoma mansoni is explored in detail, with respect to varying frequencies of treatment and the interaction between drug price and drug efficacy.

Glutamate Transport Decreases Mitochondrial pH and Modulates Oxidative Metabolism in Astrocytes.

During synaptic activity, the clearance of neuronally released glutamate leads to an intracellular sodium concentration increase in astrocytes that is associated with significant metabolic cost. The proximity of mitochondria at glutamate uptake sites in astrocytes raises the question of the ability of mitochondria to respond to these energy demands. We used dynamic fluorescence imaging to investigate the impact of glutamatergic transmission on mitochondria in intact astrocytes. Neuronal release of glutamate induced an intracellular acidification in astrocytes, via glutamate transporters, that spread over the mitochondrial matrix. The glutamate-induced mitochondrial matrix acidification exceeded cytosolic acidification and abrogated cytosol-to-mitochondrial matrix pH gradient. By decoupling glutamate uptake from cellular acidification, we found that glutamate induced a pH-mediated decrease in mitochondrial metabolism that surpasses the Ca(2+)-mediated stimulatory effects. These findings suggest a model in which excitatory neurotransmission dynamically regulates astrocyte energy metabolism by limiting the contribution of mitochondria to the metabolic response, thereby increasing the local oxygen availability and preventing excessive mitochondrial reactive oxygen species production.