Bootstrap for neural model selection

Bootstrap techniques (also called resampling computation techniques) have introduced new advances in modeling and model evaluation. Using resampling methods to construct a series of new samples which are based on the original data set, allows to estimate the stability of the parameters. Properties such as convergence and asymptotic normality can be checked for any particular observed data set. In most cases, the statistics computed on the generated data sets give a good idea of the confidence regions of the estimates. In this paper, we debate on the contribution of such methods for model selection, in the case of feedforward neural networks. The method is described and compared with the leave-one-out resampling method. The effectiveness of the bootstrap method, versus the leave-one-out methode, is checked through a number of examples.Comment: A la suite de la conf\'{e}rence ESANN 200

Angiotensin II Receptor Gene A1166C Variant and Hypertension in Tunisian Population

Many genes have been proposed as candidate genes for hypertension. Among these genes, the angiotensin II type 1 receptor gene (AGTR1) has been investigated in the pathogenesis of hypertension, but studies have often generated controversial results. In this study, we analyzed the relationship between the A1166C variant of the AGTR1 and hypertension in a sample from the Tunisian population. Analysis of the AGTR1 genotypes was performed in 388 Tunisian patients with hypertension and 428 healthy subjects by polymerase chain reaction-restriction fragment length polymorphism. The results shows that the AGTR1 genotypes distribution and allele frequencies were not significantly different between the hypertensive and normotensive subjects (p>0.05). This polymorphism was not associated with hypertension (OR = 1.03, 95% CI [0.47-2.24]; p = 0.58) for AC and (OR = 1.19, 95% CI [0.65-2.19]; p = 0.83) for CC in comparison to the AA wild homozygous. After adjustment for the confounding factors of age, gender, body mass index, fasting glucose concentration, dyslipidemia and smoking, the OR for hypertension remained no significant (OR = 1.28, 95% CI [0.87-1.84]; p = 0.50) for CC vs AA. Furthermore, no relationship was found between clinical characteristics and AGTR1 genotypes. In the conclusion; our data suggested that the A1166C variant of the AGTR1 is not involved in the pathogenesis of hypertension in the Tunisian population

ScaI Atrial Natriuretic Peptide Gene Polymorphism and Hypertension in the Tunisian Population

Numerous genetic variants have been linked to hypertension. Among these variants T2238C polymorphism in atrial natriuretic peptide gene has been investigated in the pathogeneses of hypertension, but studies have often generated controversial results. The aim of this study was to investigate the association between hypertension and the ANP/ T2238C variant gene that led to the loss of ScaI restriction site, thus eliminated the regular stop codon and involved an extension of the human ANP by two additional arginines. We genotyped 384 patients with hypertension and 435 healthy controls. The ScaI ANP gene polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. The results shows that the ScaI ANP gene polymorphism genotypes distribution and allele frequencies were not significantly different between the hypertensive and normotensive subjects (p>0.05). The frequencies of A2 wild allele and A1 mutant allele were 48% and 52% respectively in hypertensive patients and 49% and 51% in control group (p=0.66). This polymorphism is not associated with hypertension (OR= 1.55, 95% CI [0.82-2.92]; p=0.17) for TC and (OR=1.80, 95% CI [0.81-3.98]; p=0.14) for CC after adjustment for age, gender, body mass index, fasting glucose concentration, dyslipidemia and smoking. Furthermore, no relationship was found between clinical characteristics and ScaI ANP genotypes. As a conclusion; this study suggested that the ScaI ANP gene polymorphism is not associated with hypertension in the Tunisian population

Impact of nutraceuticals on markers of systemic inflammation: Potential relevance to cardiovascular diseases – A position paper from the International Lipid Expert Panel (ILEP)

Inflammation is a marker of arterial disease stemming from cholesterol-dependent to -independent molecular mechanisms. In recent years, the role of inflammation in atherogenesis has been underpinned by pharmacological approaches targeting systemic inflammation that have led to a significant reduction in cardiovascular disease (CVD) risk. Although the use of nutraceuticals to prevent CVD has largely focused on lipid-lowering (e.g, red-yeast rice and omega-3 fatty acids), there is growing interest and need, especially now in the time of coronavirus pandemic, in the use of nutraceuticals to reduce inflammatory markers, and potentially the inflammatory CVD burden, however, there is still not enough evidence to confirm this. Indeed, diet is an important lifestyle determinant of health and can influence both systemic and vascular inflammation, to varying extents, according to the individual nutraceutical constituents. Thus, the aim of this Position Paper is to provide the first attempt at recommendations on the use of nutraceuticals with effective anti-inflammatory properties

Nutraceutical approaches to non-alcoholic fatty liver disease (NAFLD): A position paper from the International Lipid Expert Panel (ILEP)

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common condition affecting around 10–25% of the general adult population, 15% of children, and even > 50% of individuals who have type 2 diabetes mellitus. It is a major cause of liver-related morbidity, and cardiovascular (CV) mortality is a common cause of death. In addition to being the initial step of irreversible alterations of the liver parenchyma causing cirrhosis, about 1/6 of those who develop NASH are at risk also developing CV disease (CVD). More recently the acronym MAFLD (Metabolic Associated Fatty Liver Disease) has been preferred by many European and US specialists, providing a clearer message on the metabolic etiology of the disease. The suggestions for the management of NAFLD are like those recommended by guidelines for CVD prevention. In this context, the general approach is to prescribe physical activity and dietary changes the effect weight loss. Lifestyle change in the NAFLD patient has been supplemented in some by the use of nutraceuticals, but the evidence based for these remains uncertain. The aim of this Position Paper was to summarize the clinical evidence relating to the effect of nutraceuticals on NAFLD-related parameters. Our reading of the data is that whilst many nutraceuticals have been studied in relation to NAFLD, none have sufficient evidence to recommend their routine use; robust trials are required to appropriately address efficacy and safety

Step‐by‐step diagnosis and management of the nocebo/drucebo effect in statin‐associated muscle symptoms patients: a position paper from the International Lipid Expert Panel (ILEP)

Statin intolerance is a clinical syndrome whereby adverse effects (AEs) associated with statin therapy [most commonly statin-associated muscle symptoms (SAMS)] result in the discontinuation of therapy and consequently increase the risk of adverse cardiovascular outcomes. However, complete statin intolerance occurs in only a small minority of treated patients (estimated prevalence of only 3–5%). Many perceived AEs are misattributed (e.g. physical musculoskeletal injury and inflammatory myopathies), and subjective symptoms occur as a result of the fact that patients expect them to do so when taking medicines (the nocebo/drucebo effect)—what might be truth even for over 50% of all patients with muscle weakness/pain. Clear guidance is necessary to enable the optimal management of plasma in real-world clinical practice in patients who experience subjective AEs. In this Position Paper of the International Lipid Expert Panel (ILEP), we present a step-by-step patient-centred approach to the identification and management of SAMS with a particular focus on strategies to prevent and manage the nocebo/drucebo effect and to improve long-term compliance with lipid-lowering therapy

Bootstrap pour la sélection de modèles neuronaux : application au positionnement des barres de combustible dans les réacteurs nucléaires

Les techniques de Bootstrap (appelées aussi re- échantillonnage) reposent sur des techniques de simulation d’échantillons à partir d’un seul échantillon. Ces techniques sont en pleine effervescence depuis la croissance des puissances de calcul des ordinateurs. Elles sont les seules procédures possibles lorsque la complexité du problème ne permet pas d’inférence classique: elles permettent d’éviter d’avoir à estimer la loi du bruit à partir des résidus, comme pour des approches de type Monte-Carlo qui exige le choix de la loi utilisée pour générer les données fictives

Bootstrap for Neural Model Selection

Bootstrap techniques (also called resampling computations techniques) have introduced new advances in modeling and model evaluation [10]. Using resampling methods, the information contained in one observed data set is extended to many typical generated data sets. These procedures based on computer simulation and cross validation are the last resort when no classical inference is possible due to the intrinsic complexity of the problem: they can avoid to estimate the noise distribution from the residuals, like in Monte-Carlo approach which is based on a hypothesized noise distribution. Resampling allows the modeler to construct a series of new samples which are based on the original data set, and then to estimate the stability of the parameters. Properties such as convergence and asymptotic normality can be checked for any particular observed data set. In most cases, the statistics computed on the generated data sets give a good idea of the confidence regions of the estimates. In this paper, we debate on the contribution of such methods for model selection, in the case of feedforward neural networks. The method is described and its effectiveness is checked through a number of examples