Do routinely measured risk factors for obesity explain the sex gap in its prevalence? Observations from Saudi Arabia.

BACKGROUND: The prevalence of adult obesity is higher in women than men in most countries. However, the pathways that link female sex with excess obesity are still not fully understood. We examine whether socioeconomic and behavioural factors may mediate the association between sex and obesity in the Saudi Arabian setting where there is female excess in obesity. METHODS: We performed a mediation analysis using a cross-sectional, national household survey from Saudi Arabia with 4758 participants (51% female). A series of multivariable regression models were fitted to test if socioeconomic position, physical activity, sedentary behaviour, diet, and smoking mediate the association between sex and obesity (BMI >=30). The findings were confirmed using causal mediation analysis. RESULTS: Women in this sample were roughly twice as likely as men to be obese (crude OR 1.9; 95% CI 1.6-2.3). The odds ratio remained significantly higher for women compared to men in models testing for mediation (OR range 1.95-2.06). Our data suggest that indicators of socio-economic position, physical activity, sedentary behaviour, diet, and smoking do not mediate the sex differences in obesity. CONCLUSIONS: Our analysis shows that most commonly measured risk factors for obesity do not explain the sex differences in its prevalence in the Saudi context. Further research is needed to understand what might explain the female excess in obesity prevalence. We discuss how data related to the lived experience of Saudi men and women may tap into underlying mechanisms by which the sex difference in obesity prevalence are produced

Exposure matters: effects of environmentally realistic exposure conditions on toxicity of model nanomaterials to Daphnia Magna

Nanomaterials (NMs) can be defined as having at least one external dimension between 1-100nm. Due to their small size, NMs have a large surface area giving them characteristics that differ from bulk material. NMs are incorporated into numerous applications making environmental exposure to NMs likely. Increased reliance on plastic results in accumulation of nano-plastics in fresh waters. Polystyrene (PS) acts as a representative of both nano-plastic and NMs. The deposition of gold (Au) NMs is also likely due to their use in medical applications so that both PS and Au have a potential to interact with environmental organisms. Daphnia manga (D. magna) is an ideal candidate in fresh water toxicity testing. Toxicity, uptake and retention of NMs by organisms is dependent on several factors such as NM charge, shape, chemical composition and the absorption of natural biomolecules binding to the surface of the NM creating an eco-corona, altering stability of the NMs thereby changing their toxicity. This work investigates the toxicity of PS and Au NMs and explores the effects of charge, shape, presence of a corona and the impact of realistic modes of presentation of NMs to D. magna and how these factors impact toxicity, uptake, retention and depuration

Molecular detection of extended spectrum ß-lactamase genes in Escherichia coli isolates from urinary tract infected patients

Extended-spectrum ß-lactamases (ESBL) are a major source of concern. ESBL have been recorded around the world. Globally, the number of people infected with Enterobacteriaceae that produce extended-spectrum beta-lactamase (ESBL) is on the rise. It has been a rise in resistance to ß-lactam antibiotics among them. In this study, the objective was to collect Escherichia coli  isolates from Urinary tract infection patients using selective medium, determine the prevalence of ESBL-producing E. coli, phylogenetic groupings of isolates, ESBL production, and biofilm formation among the isolates of E. coli isolates. The study included 250 E. coli samples from male and female subjects and grown on a selective medium. The isolated bacteria were submitted to different tests, including the detection of biofilm development and testing of the phylogenetic grouping of the E. coli isolate using triplex-PCR analysis. Representatives of each isolate were phenotypically evaluated for antibiotic resistance and classified into phylogenetic groupings. The results of extended-spectrum ß -lactams antibiotics showed the greatest resistance levels. There were 100% resistance rates for Ceftazidime-Clavulantae (CZC) and Cefotaxime-Clavulantae (CTC), 78.7% for Ceftazidime (CAZ), 86.7% for Cefotaxime CTX, 84% for Aztreonam (ATM), 87.3% for Ceftriaxone (CRO) and 83.3% for Cefpodoxime (CPD). E. coli isolates belonging to phylogroup B2 (91, 91%), and subtyping B23 (75, 75%) were the most common among UTI patients. ESBL-producing E. coli isolates were prevalent in individuals with UTIs. Most E. coli isolates from UTI patients at Al-Hillah hospitals belonged to phylogroup B2, followed by D, B1, and A. B2 was the most prevalent group in the study. This study examined the dissemination of ESBL genes in phylogenetic groups of the E. coli isolates from UTIs patients in the Al-Hillah, Iraq

Mini Review: Is fluoroquinolone drug or poison?

Quinolones are a class of broad-spectrum antibiotics with valuable pharmacological properties due to their improved pharmacokinetic properties, particular mechanism of action and broad and potent activity; being one of the fastest growing class antibacterial growths in terms of therapeutic use and overall benefit. Because of their effectiveness, spectrum of activity, and generally good safety profile, fluoroquinolones were used widely for multiple clinical indications throughout the world. Although still clinically valuable, fluoroquinolone use has become limited in some clinical situations, as bacterial resistance has emerged over time. In the sections that follow we review the range of molecular mechanisms that motivate quinolone resistance

Suivi automatique de variations modales à l’aide du technique de décrément aléatoire sans filtrage application à des enregistrements de vibrations ambiantes des bâtiments

This thesis proposes a novel approach to automatically monitor the variationsof the frequencies and the damping ratios of actual high-rise buildings subjected to realworldambient vibrations. The approach aims at dealing simultaneously with the followingchallenges: multi-component signals recorded over the aforementioned buildings and havingclosely-spaced frequency modes with low, exponential and damped amplitudes of theirimpulse responses and contaminated with high additive noises. The approach relies on theapplication of the Random Decrement Technique directly over the multi-component signalunder study which leads to the extraction of a Multi-mode Random Decrement Signatureequivalent to the system impulse response. To characterize such a signature, we propose asignal model based on the physical structure of the building from where the modal parameterscan be estimated. For the purpose of non-biased modal estimate, we propose to usean iterative method based on a Maximum-Likelihood Estimation optimized by a simulatedannealing technique. In order to initialize the parameters of the latter, a first step is designedwhich can be considered as an independent estimator of the modal parameters. Theoriginality of this step lies in its ability to automatically define the number of modes of theestimated signature through the use of the statistical properties of a Welch spectrum. Themodal parameters estimated by the spectral-based initialization step are finally refined bythe Maximum-Likelihood Estimation step. The latter reduces the bias in the estimation andyields more reliable and robust results. All these steps are defined in order to be able to automaticallymonitor the health of a building via a long-term real-time tracking of the modalvariations over time without the need to any user intervention . In addition, the proposedapproach has paid very special attention to the automatic estimation of the most problematicmodal parameter, i.e., the damping ratio. Such features making two of the original featuresas compared to existing techniques. The adaptability and functionality of AMBA is validatedover six actual buildings excited by real-world ambient vibrations. From the obtained results,AMBA proved high efficiency in automatically estimating the frequencies and moreover thedamping ratios in case of closely-spaced frequency modes and very low signal-to-noise ratiolevel. AMBA as well demonstrated a good performance for tracking the modal variationsover time.Cette thèse propose une nouvelle approche pour surveiller automatiquementles variations des fréquences et des taux d’amortissement des batiments de grande hauteursoumis à des vibrations ambiantes. L’approche vise à relever simultanément avec les défissuivants: signaux multi-composants enregistrées sur les bâtiments mentionnés ci-dessusavec des réponses impulsionnelles ayant des modes de fréquences rapprochées, des amplitudesfaibles, exponentielles et amorties noyées dans des bruits additifs élevés. La méthoderepose sur l’application de la technique de décrément aléatoire directement sur le signal multicomposantece qui conduit à l’estimation d’une signature de décrément aléatoire multi-modeéquivalente à la réponse impulsionnelle de système. Pour caractériser une telle signature,nous proposons un modèle de signal basé sur la structure physique du bâtiment à partir delaquelle les paramètres modaux peuvent être estimés. Dans le but d’avoir une estimationnon biaisée, nous proposons d’utiliser une méthode itérative sur la base d’une estimation dumaximum de vraisemblance optimisé par une technique de recuit simulé. Afin d’initialiserles paramètres de ce dernier, une première étape est conçu qui peut être considéré commeun estimateur indépendant des paramètres modaux. L’originalité de cette étape réside danssa capacité à définir automatiquement le nombre de modes de la signature estimé grâce àl’utilisation des propriétés statistiques d’un spectre estimé par une transformée de Fourier.Les paramètres modaux estimés par l’étape d’initialisation sont finalement affinés par l’étaped’estimation du maximum de vraisemblance. Celui-ci réduit le biais de l’estimation et donnedes résultats plus fiables et plus robustes. Toutes ces étapes sont définies de manière à être enmesure de surveiller automatiquement l’état de santé d’un bâtiment par l’intermédiaire d’unsuivi long terme en temps réel des variations modales dans le temps sans que l’interventionde l’utilisateur soit nécessaire. En outre, l’approche proposée a accordé une attention touteparticulière à l’estimation automatique du paramètre modal les plus problématique, c’està-dire, le taux d’amortissement. Ces deux caractéristiques sont des atouts originaux parrapport aux techniques existantes. L’adaptabilité et la fonctionnalité de l’AMBA a été validésur six bâtiments réels excités par des vibrations ambiantes. D’après les résultats obtenus,AMBA a prouvé une grande efficacité dans l’estimation automatique des fréquences et destaux d’amortissement dans le cas de modes de fréquences rapprochées et avec un très faiblerapport signal-sur-bruit. AMBA a ainsi démontré une bonne performance pour suivre lesvariations modales au fil du temps

An automatic approach towards modal parameter estimation for high-rise buildings of multicomponent signals under ambient excitations via filter-free Random Decrement Technique

International audienceThis paper proposes an automatic modal analysis approach for signals of high-rise buildings recorded under real-world ambient excitations. The fact of working over such type of signals is faced with several challenges: the time-domain convolution between the system impulse response and the seismic noise, the existence of several components, the presence of closely-spaced frequency modes, with high additive noises, and low, exponential and damped amplitudes. The proposed approach handles these challenges simultaneously without the need for a user intervention. It is based on a filter-free Random Decrement Technique to estimate the free-decay response, followed by a spectral-based method for a rough modal estimate and finalized by a Maximum-Likelihood Estimation process to refine the modal estimates. Each of these processes is responsible to tackle one or more of the aforementioned challenges in the aim to provide an automatic and moreover a reliable modal analysis of the studied signals

Non-biased estimation of modal parameters of multi-component ambient vibrations in high-rise buildings using a self-governed random decrement technique

International audienceThe estimation of modal parameters of a structure by applying the random decrement technique has been introduced since late 1960's, and is widely used because of its simplicity and rapidity. Since this technique can be applied to mono-component signals only, a filtering process is a necessary preliminary step for getting the random decrement signature when applying on multi-component signals. But filtering is the most critical step with a high influence on the accuracy of the modal parameter estimation, especially when the signal is composed of very closely-spaced modes. In this paper, we propose to apply the random decrement technique directly on a multi-component signal without the filtering step, in order to provide what we called a multi-mode signature. The idea is then to propose an adapted method to separate the different modes in this multi-mode signature. For that purpose the modal parameters are first roughly approximated in a non-optimal way and with a bias from a time-frequency distribution. Based on this initialization, a final non-biased estimation is achieved via maximum likelihood estimator. The results conducted in this paper, over simulated and real world ambient vibrations on high rise buildings, suggest positively that the proposed method is totally autonomous and is capable of yielding very good estimation results

Automatic Parameter Setting of Random Decrement Technique for the Estimation of Building Modal Parameters

International audienceThis paper examines the use of the Random Decrement Technique (RDT) for the estimation of building modal parameters, in particular the natural frequency and the damping ratio. It focuses on establishing the processing parameters one must specify to use the technique to its best advantage. This work is motivated by the high influence of these parameters on the RDT quality. Despite the widespread use of the RDT and the enormous effort for understanding the choice of its parameters, no work has been done on how to automate this selection. From this point, this paper comes out with a proposition of an automatic procedure to guide up the choice of these parameters. The results of this paper, on simulated and real-world ambient vibrations, indicate that the proposed automatic setting procedure of the different parameters of the RDT has opened the way to more reliable results and much credible estimation of the modal parameters