441 research outputs found

    Protection of polyunsaturated fatty acids against ruminal biohydrogenation using polyphenol oxidase

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    Increasing the polyunsaturated fatty acid (PUFA) content of food products is an important aspect to obtain a healthy diet. Improving the PUFA content of monogastric products such as pork meat, chicken meat or eggs can be achieved relatively easily by increasing their level of ingested PUFA-rich lipids, but increasing PUFA in ruminant products such as beef or milk is much more challenging. Ruminants have the unique ability to digest fibrous rich materials due to the presence of a wide range of microorganisms in the rumen, but a consequence of this symbiosis is the biohydrogenation of PUFA by ruminal bacteria, which limits its transfer from the diet to the milk and meat. A new rumen bypass technology was developed to protect lipids from the undesired turnover of dietary unsaturated ‘healthy’ fatty acids to more saturated ‘unhealthy’ forms in ruminants. Protection was made by use of emulsions and the naturally occurring and omnipresent browning enzyme polyphenol oxidase. This enzyme could be extracted from a wide variety of plant resources, including potato tuber peels. It was hypothesized proteins at the emulsion interface were cross-linked upon addition of a diphenol, which forms a protective interfacial barrier. Results from this thesis demonstrate PUFA could be protected against ruminal breakdown and released post-ruminally from their protected shell, and to some extent transferred to the mammary gland. Healthier milk and meat could be obtained by this technology, whereby protein-rich sidestreams containing this enzyme can be upgraded and valorized

    Optical momentum distributions in monochromatic, isotropic random vector fields

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    We investigate the decomposition of the electromagnetic Poynting momentum density in three-dimensional random monochromatic fields into orbital and spin parts, using analytical and numerical methods. In sharp contrast with the paraxial case, the orbital and spin momenta in isotropic random fields are found to be identically distributed in magnitude, increasing the discrepancy between the Poynting and orbital pictures of energy flow. Spatial correlation functions reveal differences in the generic organization of different optical momenta in complex natural light fields, with the orbital current typically forming broad channels of unidirectional flow, and the spin current manifesting larger vorticity and changing direction over subwavelength distances. These results are extended to random fields with pure helicity, in relation to the inclusion of electric-magnetic democracy in the definition of optical momenta

    The 1991-2004 Evolution in Life Expectancy by Educational Level in Belgium Based on Linked Census and Population Register Data

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    The aim of this study is to determine trends in life expectancy by educational level in Belgium and to present elements of interpretation for the observed evolution. The analysis is based on census data providing information on educational level linked to register data on mortality for the periods 1991–1994 and 2001–2004. Using exhaustive individual linked data allows to avoid selection bias and numerator–denominator bias. The trends reveal a general increase in life expectancy together with a widening social gap. Summary indices of inequality based on life expectancies show, however, a more complex pattern and point to the importance to include the shifts in population composition by educational level in an overall assessment of the evolution of inequality by educational level.L’objectif de l’étude est de déterminer le sens et l’ampleur de l’évolution des inégalités en espérance de vie en Belgique selon le niveau d’instruction. L’analyse part des données des recensements qui fournissent l’information sur le niveau d’instruction. Ces données ont été liées au registre de la population qui fournit l’information sur la mortalité pour les périodes 1991–1994 et 2001–2004. L’utilisation de données exhaustives et d’un enregistrement de la mortalité lié directement aux données du recensement évite des erreurs de sélection et du biais entre numérateur et dénominateur. On peut constater qu’en général l’espérance de vie progresse pour tous les niveaux d’éducation mais que cela va de pair avec un élargissement des inégalités. L’utilisation d’indices d’inégalité montre néanmoins une réalité plus complexe et la nécessité d’inclure l’évolution de la composition de la population par niveau d’éducation dans une évaluation globale de l’évolution des inégalités

    Transcutaneous vagus nerve stimulation does not affect verbal memory performance in healthy volunteers

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    Introduction: Invasive vagus nerve stimulation (VNS) improves word recognition memory in patients with epilepsy. Recent studies with transcutaneous VNS (tVNS) have also shown positive effects on various subdomains of cognitive functioning in healthy volunteers. In this randomized, controlled, crossover study, we investigated the effect of tVNS on a word recognition memory paradigm in healthy volunteers to further investigate the potential of tVNS in the treatment of cognitive disorders. Methods: We included 41 healthy participants aged between 18 and 30 years (young age group) and 24 healthy participants aged between 45 and 80 years (older age group). Each participant completed a word recognition memory paradigm during three different conditions: true tVNS, sham, and control. During true tVNS, stimulation was delivered at the cymba conchae. Sham stimulation was delivered by stimulating the earlobe. In the control condition, no stimulation was given. In each condition, participants were asked to remember highlighted words from three test paragraphs. Accuracy scores were calculated for immediate recall after each test paragraph and for delayed recognition at the end of the paradigm. We hypothesized that highlighted words from paragraphs in the true tVNS condition would be more accurately recalled and/or recognized compared to highlighted words from paragraphs in the sham or control condition. Results: In this randomized study, tVNS did not affect the accuracy scores for immediate recall or delayed recognition in both age groups. The younger group showed significantly higher accuracy scores than the older group. The accuracy scores improved over time, and the most recently learned words were better recognized. Participants rated true tVNS as significantly more painful; however, pain was not found to affect accuracy scores. Conclusion: In this study, tVNS did not affect verbal memory performance in healthy volunteers. Our results could not replicate the positive effects of invasive VNS on word recognition memory in epilepsy patients. Future research with the aim of improving cognitive function should focus on the rational identification of optimized and individualized stimulation settings primarily in patients with cognitive deficits

    Educational inequalities in premature mortality by region in the Belgian population in the 2000s

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    Background: In Belgium, socio-economic inequalities in mortality have long been described at country-level. As Belgium is a federal state with many responsibilities in health policies being transferred to the regional levels, regional breakdown of health indicators is becoming increasingly relevant for policy-makers, as a tool for planning and evaluation. We analyzed the educational disparities by region for all-cause and cause-specific premature mortality in the Belgian population. Methods: Residents with Belgian nationality at birth registered in the census 2001 aged 25-64 were included, and followed up for 10 years though a linkage with the cause-of-death database. The role of 3 socio-economic variables (education, employment and housing) in explaining the regional mortality difference was explored through a Poisson regression. Age-standardised mortality rates (ASMRs) by educational level (EL), rate differences (RD), rate ratios (RR), and population attributable fractions (PAF) were computed in the 3 regions of Belgium and compared with pairwise regional ratios. The global PAFs were also decomposed into the main causes of death. Results: Regional health gaps are observed within each EL, with ASMRs in Brussels and Wallonia exceeding those of Flanders by about 50% in males and 40% in females among Belgian. Individual SE variables only explained up to half of the regional differences. Educational inequalities were also larger in Brussels and Wallonia than in Flanders, with RDs ratios reaching 1.8 and 1.6 for Brussels versus Flanders, and Wallonia versus Flanders respectively; regional ratios in relative inequalities (RRs and PAFs) were smaller. This pattern was observed for all-cause and most specific causes of premature mortality. Ranking the cause-specific PAFs revealed a higher health impact of inequalities in causes combining high mortality rate and relative inequality, with lung cancer and ischemic heart disease on top for all regions and both sexes. The ranking showed few regional differences. Conclusions: For the first time in Belgium, educational inequalities were studied by region. Among the Belgian, educational inequalities were higher in Brussels, followed by Wallonia and Flanders. The region-specific PAF decomposition, leading to a ranking of causes according to their population-level impact on overall inequality, is useful for regional policy-making processes

    Soft, comfortable polymer dry electrodes for high quality ECG and EEG recording

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    Conventional gel electrodes are widely used for biopotential measurements, despite important drawbacks such as skin irritation, long set-up time and uncomfortable removal. Recently introduced dry electrodes with rigid metal pins overcome most of these problems; however, their rigidity causes discomfort and pain. This paper presents dry electrodes offering high user comfort, since they are fabricated from EPDM rubber containing various additives for optimum conductivity, flexibility and ease of fabrication. The electrode impedance is measured on phantoms and human skin. After optimization of the polymer composition, the skin-electrode impedance is only similar to 10 times larger than that of gel electrodes. Therefore, these electrodes are directly capable of recording strong biopotential signals such as ECG while for low-amplitude signals such as EEG, the electrodes need to be coupled with an active circuit. EEG recordings using active polymer electrodes connected to a clinical EEG system show very promising results: alpha waves can be clearly observed when subjects close their eyes, and correlation and coherence analyses reveal high similarity between dry and gel electrode signals. Moreover, all subjects reported that our polymer electrodes did not cause discomfort. Hence, the polymer-based dry electrodes are promising alternatives to either rigid dry electrodes or conventional gel electrodes

    Vesicle coat proteins: Finding the missing link

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    The discovery of an ancient protein complex reveals the evolutionary relationships between the proteins that help to form vesicles

    Evolution of educational inequalities in life and health expectancies at 25 years in Belgium between 2001 and 2011 : a census-based study

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    Background: Reducing socio-economic health inequalities is a public health priority, necessitating careful monitoring that should take into account changes in the population composition. We analyzed the evolution of educational inequalities in life expectancy and disability-free life expectancy at age 25 (LE25 and DFLE25) in Belgium between 2001 and 2011. Methods: The 2001 and 2011 census data were linked with the national register data for a five-year mortality follow up. Disability prevalence estimates from the health interview surveys (2001 to 2013) were used to compute DFLE according to Sullivan's method. LE25 and DFLE25 were computed by educational level (EL). Absolute differentials of LE25 and DFLE25 were calculated for each EL and for each period, as well as composite inequality indices (CII) of population-level impact of inequality. Changes over the 10-year period were then calculated for each inequality index. Results: The LE25 increased in all ELs and both genders, except in the lowest EL for women. The increase was larger in the highest EL, leading in 2011 to 6.07 and 4.58 years for the low-versus-high LE25 gaps respectively in men and women, compared to 5.19 and 3.76 in 2001, namely 17 and 22% increases. The upwards shift of the EL distribution led to a limited 7% increase of the CII among men but no change in women. The substantial increase of the DFLE25 in males with high EL (+4.5 years) and the decrease of the DFLE25 in women with low EL, results in a substantial increase of all considered DFLE25 inequality measures in both genders. In 2011, DFLE25 gaps were respectively 10.4 and 13.5 years in males and females compared to 6.51 and 9.30 in 2001, representing increases of 61 and 44% for the gaps, and 72 and 20% for the CII. Conclusion: The LE25 increased in all ELs, but at a higher pace in highly educated, leading to an increase in the LE25 gaps in both genders. After accounting for the upwards shift of the educational distribution, the population-level inequality index increased only for men. The DFLE25 increased only in highly educated men, and decreased in low educated women, leading to large increases of inequalities in both genders. A general plan to tackle health inequality should be set up, with particular efforts to improve the health of the low educated women
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