192 research outputs found
The impact of favouritism on the business climate: a study on Wasta in Jordan
"Wide-ranging agreement exists today that a good business climate is central to economic growth and poverty alleviation. But questions remain open about the role of the state in creating a good business climate. This study is intended to answer some of these questions. The Arab Human Development Report 2004 stresses that sustainable economic growth cannot be achieved in the MENA countries without improved governance. One of the core dimensions of good governance is transparency and the control of corruption. The latter in particular is important for a good business climate (World Bank 2005f). Corruption can take different forms, one of them being favouritism which is very widespread in the MENA region. It is usually referred to there as 'wasta', which is Arabic for 'relation' or 'connection', and describes the use of personal relations for preferential treatment. The present study focuses on the economic effects of wasta. It has a twofold aim: first to find out how the use of wasta in state-business relations affects the business climate and investment and, thereby, economic development at large, and, second, to identify starting points for curtailing the use of wasta. All reference is hereby to Jordan, which has been selected for this case study for pragmatic reasons. Chapter 2 presents the conceptual framework of the study: It defines first the key terms and concepts of the study: business climate, state-business relations, favouritism, and wasta. After that, it discusses in general terms why and how favouritism may affect the business climate. Finally, the chapter draws upon theoretical literature to give possible explanations for the prevalence of favouritism in a given country. Chapter 3 is based on the results of Chapter 2 and delineates the hypotheses tested by our empirical research in Jordan. In addition, it gives a detailed account of our research methodology. Chapter 4 outlines the main features of the business climate in Jordan: It identifies the main problems perceived by businesspeople and discusses possible reasons for these weaknesses. The chapter concludes that statebusiness relations are a major area of concern for investors in Jordan. Chapter 5 turns to the role of wasta in Jordan. It shows how the use of wasta permeates all areas of economic and social life and gives an insight into the ambiguous attitudes of Jordanians toward wasta. Chapter 6 is devoted to the effects of wasta on the business climate and on investment. It shows that the prevalence of wasta in Jordan makes statebusiness relations unfair and inefficient. In addition, wasta establishes incentives for investment in social relations rather than in productive capital,thus lowering the rate of capital formation in Jordan. Chapter 7 concludes with policy recommendations." (excerpt
A Large-scale Virtual Patient Cohort to Study ECG Features of Interatrial Conduction Block
Interatrial conduction block refers to a disturbance in the propagation of electrical impulses in the conduction pathways between the right and the left atrium. It is a risk factor for atrial fibrillation, stroke, and premature death. Clinical diagnostic criteria comprise an increased P wave duration and biphasic P waves in lead II, III and aVF due to retrograde activation of the left atrium. Machine learning algorithms could improve the diagnosis but require a large-scale, well-controlled and balanced dataset. In silico electrocardiogram (ECG) signals, optimally obtained from a statistical shape model to cover anatomical variability, carry the potential to produce an extensive database meeting the requirements for successful machine learning application. We generated the first in silico dataset including interatrial conduction block of 9,800 simulated ECG signals based on a bi-atrial statistical shape model. Automated feature analysis was performed to evaluate P wave morphology, duration and P wave terminal force in lead V1. Increased P wave duration and P wave terminal force in lead V1 were found for models with interatrial conduction block compared to healthy models. A wide variability of P wave morphology was detected for models with interatrial conduction block. Contrary to previous assumptions, our results suggest that a biphasic P wave morphology seems to be neither necessary nor sufficient for the diagnosis of interatrial conduction block. The presented dataset is ready for a classification with machine learning algorithms and can be easily extended
Efficient time splitting schemes for the monodomain equation in cardiac electrophysiology
Approximating the fast dynamics of depolarization waves in the human heart described by the monodomain model is numerically challenging. Splitting methods for the PDE-ODE coupling enable the computation with very fine space and time discretizations. Here, we compare different splitting approaches regarding convergence, accuracy, and efficiency. Simulations were performed for a benchmark problem with the Beeler–Reuter cell model on a truncated ellipsoid approximating the left ventricle including a localized stimulation. For this configuration, we provide a reference solution for the transmembrane potential. We found a semi-implicit approach with state variable interpolation to be the most efficient scheme. The results are transferred to a more physiological setup using a bi-ventricular domain with a complex external stimulation pattern to evaluate the accuracy of the activation time for different resolutions in space and time
Efficient time splitting schemes for the monodomain equation in cardiac electrophysiology
Approximating the fast dynamics of depolarization waves in the human heart described by the monodomain model is numerically challenging. Splitting methods for the PDE-ODE coupling enable the computation with very fine space and time discretizations. Here, we compare different splitting approaches regarding convergence, accuracy and efficiency. Simulations were performed for a benchmark configuration with the Beeler–Reuter cell model on a truncated ellipsoid approximating the left ventricle including a localized stimulation. For this benchmark configuration, we provide a reference solution for the transmembrane potential. We found a semi-implicit approach with state variable interpolation to be the most efficient scheme. The results are transferred to a more physiological setup using a bi-ventricular domain with a complex external stimulation pattern to evaluate the accuracy of the activation time for different resolutions in space and time
Acute type A aortic dissection and pregnancy: a population-based study
Objective: Pregnancy has been reported to be an independent risk factor for 50% of acute aortic dissections recorded in women younger than 45 years of age. The present epidemiologic study aimed to identify whether this putative association of pregnancy and acute type A dissection could be an artifact of selective reporting. Methods: This population-based study was conducted in the City of Vienna, Austria, Europe, in an average female population of 341381 women in the age range of 15-45 years who were followed up between 1994 and 2004 (total of 3755.195 person-years of observation). During this study, the incidence, management, and outcome of acute type A dissection were determined. Results: Fifteen patients (mean age: 38.8 years, SD: 4.8) with acute aortic dissection were identified, and an overall incidence of 0.4 case per 100000 person-years was estimated. The prehospital mortality rate was recorded to be 53%. Six patients, including two women in late pregnancy (incidence: 0.05 cases per 100000 person-years), were treated successfully by surgical repair during deep hypothermic circulatory arrest (in-hospital mortality rate: 6.6%). Pregnancy and aortic dissection were identified as events that were not related (RR: 3.27; 95% confidence interval (CI): 0.82-12.95; P=0.14). Observation during long-term follow-up was uneventful. Conclusions: Acute aortic dissection represents a rare pathology in women younger than 45 years of age; however, it is associated with a high rate of sudden death. Pregnancy may not be a risk factor for this life-threatening vascular emergency. Immediate referral to surgery, even during pregnancy, will result in a prognosis of favorable outcom
Discrepancy Between LGE-MRI and Electro-Anatomical Mapping for Regional Detection of Pathological Atrial Substrate
Atrial fibrillation (AF) is the most common sustained arrhythmia posing a significant burden to patients and leading to an increased risk of stroke and heart failure. Additional ablation of areas of arrhythmogenic substrate in the atrial body detected by either late gadolinium enhancement magnetic resonance imaging (LGE-MRI) or electroanatomical mapping (EAM) may increase the success rate of restoring and maintaining sinus rhythm compared to the standard treatment procedure of pulmonary vein isolation (PVI). To evaluate if LGE-MRI and EAM identify equivalent substrate as potential ablation targets, we divided the left atrium (LA) into six clinically important regions in ten patients. Then, we computed the correlation between both modalities by analyzing the regional extents of identified pathological tissue. In this regional analysis, we observed no correlation between late gadolinium enhancement (LGE) and low voltage areas (LVA), neither in any region nor with regard to the entire atrial surface (-0.3<r<0.3). Instead, the regional extents identified as pathological tissue varied significantly between both modalities. An increased extent of LVA compared to LGE was observed in the septal wall of the LA (= 19.63% and = 3.94%, with = median of the extent of pathological tissue in the corresponding region). In contrast, in the inferior and lateral wall, the extent of LGE was higher than the extent of LVA for most geometries (= 27.22% and = 32.70% compared to = 9.21% and = 6.69%). Since both modalities provided discrepant results regarding the detection of arrhythmogenic substrate using clinically established thresholds, further investigations regarding their constraints need to be performed in order to use these modalities for patient stratification and treatment planning
Type 2 Endoleaks: The Diagnostic Performance of Non-Specialized Readers on Arterial and Venous Phase Multi-Slice CT Angiography.
PURPOSE: To define the diagnostic precision of non-specialized readers in the detection of type 2 endoleaks (T2EL) in arterial versus venous phase acquisitions, and to evaluate an approach for radiation dose reduction. METHODS: The pre-discharge and final follow-up multi-slice CT angiographies of 167 patients were retrospectively analyzed. Image data were separated into an arterial and a venous phase reading set. Two radiology residents assessed the reading sets for the presence of a T2EL, feeding vessels, and aneurysm sac size. Findings were compared with a standard of reference established by two experts in interventional radiology. The effective dose was calculated. RESULTS: Overall, experts detected 131 T2ELs, and 331 feeding vessels in 334 examinations. Persistent T2ELs causing aneurysm sac growth > 5 mm were detected in 20 patients. Radiation in arterial and venous phases contributed to a mean of 58.6% and 39.0% of the total effective dose. Findings of reader 1 and 2 showed comparable sensitivities in arterial sets of 80.9 versus 85.5 (p = 0.09), and in venous sets of 73.3 versus 79.4 (p = 0.15), respectively. Reader 1 and 2 achieved a significant higher detection rate of feeding vessels with arterial compared to venous set (p = 0.04, p < 0.01). Both readers correctly identified T2ELs with growing aneurysm sac in all cases, independent of the acquisition phase. CONCLUSION: Arterial acquisitions enable non-specialized readers an accurate detection of T2ELs, and a significant better identification of feeding vessels. Based on our results, it seems reasonable to eliminate venous phase acquisitions
Cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) imaging in the diagnosis and follow-up of patients with acute myocarditis and chronic inflammatory cardiomyopathy : A review paper with practical recommendations on behalf of the European Society of Cardiovascular Radiology (ESCR).
Advanced cardiac imaging techniques such as cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) are widely used in clinical practice in patients with acute myocarditis and chronic inflammatory cardiomyopathies (I-CMP). We aimed to provide a review article with practical recommendations from the European Society of Cardiovascular Radiology (ESCR), in order to guide physicians in the use and interpretation of CMR and PET in clinical practice both for acute myocarditis and follow-up in chronic forms of I-CMP
Correction: Type 2 Endoleaks: The Diagnostic Performance of Non-Specialized Readers on Arterial and Venous Phase Multi-Slice CT Angiography.
[This corrects the article DOI: 10.1371/journal.pone.0149725.]
Functional evaluation of coronary disease by CT angiography
Publisher Copyright: © 2015 American College of Cardiology Foundation.In recent years, several technical developments in the field of cardiac computed tomography (CT) have made possible the extraction of functional information from an anatomy-based examination. Several different lines have been explored and will be reviewed in the present paper, namely: 1) myocardial perfusion imaging; 2) transluminal attenuation gradients and corrected coronary opacification indexes; 3) fractional flow reserve computed from CT; and 4) extrapolation from atherosclerotic plaque characteristics. In view of these developments, cardiac CT has the potential to become in the near future a truly 2-in-1 noninvasive evaluation for coronary artery disease.publishersversionpublishe
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