Vanmaercke M.,Catholic University of Leuven |
Vanmaercke M.,Fund for Scientific Research Flanders |
Poesen J.,Catholic University of Leuven |
Verstraeten G.,Catholic University of Leuven |
And 2 more authors.
Geomorphology | Year: 2011
Our understanding about the regional variation of Sediment Yield (SY) in Europe and its scale dependency currently relies on a limited number of data for mainly larger river systems. SY is the integrated result of all erosion and sediment transporting processes operating in a catchment and is therefore of high value for environmental studies and monitoring purposes. Most global assessments of SY consider catchment area (A), climate and topography as the main explanatory variables. However, it is still unclear if these factors also control regional variations of SY within Europe. This paper aims at bridging this gap. Therefore, we i) present a large database of SY-values which was constructed through an extensive literature review; ii) describe the spatial patterns of SY across Europe; and iii) explore its relation with A, climate, and topography.In total, sediment yield data from 1794 different locations throughout Europe were collected (507 reservoirs and 1287 gauging stations), representing a minimum of 29,203 catchment-year data. Only SY-data measured at gauging stations or derived from reservoir siltation rates over a period of a minimum of one year were included in the database. This database comprises a large range of catchment areas (A): i.e from small upland catchments (≥ 0.01. km2) to major European river basins (≤1,360,000. km2). An overview of the collected SY-data is provided and sources of uncertainty on the available data are discussed.Despite potentially large uncertainties on several of the individual SY-values, analysis of this database indicates clear spatial patterns of SY in Europe. The temperate and relatively flat regions of Western, Northern and Central Europe generally have relatively low SY-values (with ca. 50% of the SY<40tkm-2yr-1 and ca. 80% of the data <200tkm-2yr-1), while Mediterranean and Mountainous regions generally have higher SY-values (with around 85% of the SY-data >40tkm-2yr-1 and more than 50% of the data >200tkm-2yr-1). These differences are attributed to a combination of factors, such as differences in climate, topography, lithology and land use. Although larger differences in SY were found between the climatic regions than between topographic zones, it is currently difficult to identify the individual importance of the various controlling factors of SY. SY-A relationships were calculated for the entire dataset and for subgroups stratified according to the measurement method (gauging stations or reservoir surveys), range of the catchment area, climatic region, topographic zone of the river outlet, and major European river system. Although typically a negative relationship between SY and A is expected due to a decrease in topsoil erosion rates on more gentle slopes and an increase in sediment deposition with an increase in catchment size, this relationship was found to be generally very weak and subject to a lot of scatter. Furthermore, results illustrate important differences in scale dependency: whereas a weak but significant negative trend is generally observed for the temperate and relatively flat regions, no significant or even positive trends were observed in mountain regions and Mediterranean Europe. When only larger river catchments (i.e. > 100. km2 and especially >10,000. km2) are considered, catchment area exerted a larger control on SY. These findings confirm previous studies and indicate that the relationship between SY, spatial scale and other controlling factors is often complex and non-linear. © 2011 Elsevier B.V.
de Donder L.,Vrije Universiteit Brussel |
de Witte N.,Vrije Universiteit Brussel |
de Witte N.,University College Ghent |
Buffel T.,Vrije Universiteit Brussel |
And 3 more authors.
Research on Aging | Year: 2012
The aim of this study was to examine the relation between social capital, defined in terms of social ties, place attachment, and civic participation, and feelings of unsafety in later life. Survey data for 24,962 people aged 60 years and older from 85 municipalities across Belgium provided the empirical evidence for the analysis. The results of the multiple regression analysis reveal that a lack of opportunities for political participation is the most important factor in interpreting feelings of unsafety. In addition, several features of place attachment proved to be associated with feelings of unsafety, such as neighborhood satisfaction and neighborhood involvement. Finally, some recommendations to reduce feelings of unsafety among older people are discussed. The results point to the need to enhance opportunities to give older people a voice in the process of political decision making as an important action in reducing feelings of unsafety. © The Author(s) 2012.
Loozen G.,Health Science University |
Ozcelik O.,Cukurova University |
Boon N.,Ghent University |
De Mol A.,Health Science University |
And 4 more authors.
Journal of Clinical Periodontology | Year: 2014
Aim Although the complexity of the oral ecology and the ecological differences between health and disease are well accepted, a clear view on the dynamics in relation to disease is lacking. In this study, the prevalence and abundance of 20 key oral bacteria was assessed in health and disease and more importantly a closer look was given to the inter-bacterial relationships. Materials and methods A blinded microbiological database was analysed in this cross-sectional, retrospective study. The database was constructed based on microbiological analyses of samples from 6308 patients, with gradations of periodontitis (healthy to periodontitis). Data concerning the abundance of 20 oral bacteria and probing pocket depth were provided. Results Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Eubacterium nodatum, Porphyromonas micra and Porphyromonas intermedia showed a clear increase in abundance and prevalence with increasing pocket depth. Correlation matrices illustrated that almost all microorganisms were in one way correlated to other species and most of these correlations were significant. Several beneficial bacteria showed strong correlations with other beneficial bacteria. Conclusion Knowledge on bacterial correlations can pave the way for new treatment options focusing on restoring the shifted balance. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Zenebe A.,Mekelle University |
Vanmaercke M.,Catholic University of Leuven |
Vanmaercke M.,Fund for Scientific Research Flanders |
Verstraeten G.,Catholic University of Leuven |
And 7 more authors.
Zeitschrift fur Geomorphologie | Year: 2013
Water availability has for long been a critical issue in many developing countries. Despite its enormous potential of water resources, Ethiopia is suffering from a lack of water availability and threatened by the consequences of climate change. Well-considered planning to develop these resources is crucial. However, very few observational runoff data exist for this type of environments. Especially runoff data for catchments at the intermediate scale (100- 10,000 km2) are lacking. This study assesses the runoff from 10 medium-sized catchments in the Geba river basin, a subcatchment of the Nile in the semi-arid degraded northern Ethiopian highlands. Flow depth records were automatically obtained every 10 minutes during the rainy seasons (July-September) of 2004-2007 and converted to continuous runoff discharge records. Cumulative annual runoff depths (46-395 mm) are mainly correlated with rainfall depth. Estimated runoff coefficients (9-47%) and are negatively correlated with the areal fraction of limestone outcrops in the catchments, indicating runoff transmission losses. Throughout the rainy season, increases in runoff depth and runoff coefficient were observed, which is partly attributed to an increase in baseflow throughout the season. The majority of the runoff occurs during flash floods, i. e. relatively short runoff events with often very high peak discharges. Characteristics of these floods are discussed with some examples, including an exceptionally large flood. Taking into account the difficult conditions for river discharge measurements, this study provides one of the most comprehensive analyses so far of the magnitude and dynamics of river discharges in Ethiopia. © 2012 Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany.
News Article | October 27, 2016
Proteins often don't do anything in our cells by themselves. Their role in a given physiological process - good or bad - is typically determined by binding to one or more other proteins. So as researchers try to figure out why the enzyme PP2A is implicated in many cancers, a new study provides a potentially significant break in the case. It identifies 98 proteins that are very likely to bind with PP2A, making them potential partners in crime worth investigating. The discovery is the result of a detailed study of PP2A's structure down to the atomic level by a team of four scientists at Brown University and one in Leuven, Belgium. By determining exactly how PP2A physically binds with other proteins, the scientists were able to figure out which other proteins are a strong fit. Most of the proteins on the list are news to the biological community. Moreover, the study data could help scientists to predict how strongly each protein, or "substrate" binds PP2A. It could also offer clues on how to prevent a binding if it turns out to be disease-causing, for instance because it misregulates a process in a cell. "PP2A is a very important enzyme, but identifying its substrates and its regulators has been exceptionally difficult and part of the reason is we didn't understand how they were engaging with this protein," said corresponding author Rebecca Page, a Professor of molecular biology, cellular biology and biochemistry at Brown University and corresponding author of the paper in the journal Structure. Brown graduate student Xinru Wang and postdoctoral researcher Rakhi Bajaj led the effort to find PP2A's closest binding partners. Their main strategy was to bind the regulatory subunit of PP2A, called B56, with three shortened versions of two proteins already known to be associated: "BubR1" and "RepoMan." They made each of those protein complexes into crystals, which can be analyzed in atomic detail using X-rays. This procedure gave them a close look at which key binding interactions were consistent and which other interactions made each union unique. "The similarities were the common features that we used to identify additional PP2A interactors," Wang said. And, Page added, "The differences between RepoMan and BubR1 was what allowed us to explain why the binding affinities were different and how different PP2A regulators might be competing in the cell." One of the key similarities they observed, for example, was that PP2A has two distinct pockets at a key location on its surface where other proteins can dock if they have the right protrusions. A key difference they noticed is that RepoMan's binding is much stronger than that of BubR1 and they could discern structurally why that was - RepoMan builds an extra "salt bridge" to solidify its connection. The researchers used these observations and others made from studying the three crystallized bindings to guide a search of databases of human proteins. By looking for specific amino acid sequences in proteins the scientists were able to tell how well they might fold up and bind to PP2A. Page said that with conservative criteria - looking only for the best and most likely matches - they found 98 proteins with strong likelihoods. A few of them were already known to associate with PP2A - confirming that the approach makes sense --but many more are novel. Biologists can now study and tinker with the newly identified proteins to see whether any of them conspire with PP2A to throw processes such as cell division out of whack, leading to tumor growth, Page said. "These new proteins provide targets that we can now go investigate in detail in cells to see what consequences changing these sequences have on their activity," she said. The team has already seen some potential links in their new data to cancer, Bajaj said. For example, a mutation that replaces amino acid Histidine 243 on PP2A-B56 is found in germ cell tumors (called Embryonal carcinoma). The data might help explain why. The team saw that this amino acid makes particularly important contacts in PP2A binding to its partners. In addition to Wang, Bajaj and Page, the paper's other authors are Professor Wolfgang Peti of Brown and Mathieu Bollen of Leuven. The National Institutes of Health (1R01NS091336, R01GM098482), the Fund for Scientific Research Flanders and a Flemish Concerted Research Action grant funded the study. The researchers acquired some of their data using the Brown University Structural Biology Core Facility.
Luyckx K.,Catholic University of Leuven |
Luyckx K.,Fund for Scientific Research Flanders |
Seiffge-Krenke I.,University of Mainz |
Hampson S.E.,Oregon Research Institute
Diabetes Care | Year: 2010
OBJECTIVE - This study examines how active coping and withdrawal, psychological (internalizing and externalizing) symptoms, and glycemic control (A1C values) influence each other across time in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS - One hundred and nine adolescents participated in a four-wave longitudinal study spanning four years (mean age at Time 1 was 13.77). Patients were visited at home and completed questionnaires measuring coping and psychological symptoms. The treating physicians were contacted to obtain A1C values. Cross-lagged path analysis from a structural equation modeling approach was used for data analysis. RESULTS - Clinically meaningful pathways between coping and glycemic control were found across time. Active coping prospectively predicted lower A1C levels, which, in turn, predicted active coping. Higher A1C levels and higher psychological symptoms consistently predicted avoidance coping across time. Finally, psychological symptomatology constituted an important link in the observed longitudinal chain of effects. More specifically, higher A1C values and symptomatology at Time 1 positively predicted withdrawal at Time 2, which, in turn, positively predicted symptomatology at Time 3. Next, symptomatology at Time 3 positively predicted higher A1C values at Time 4, thus coming full circle. CONCLUSIONS - Coping with everyday stress, psychological symptoms, and glycemic control were interrelated across time. Evidence was obtained for reciprocal pathways and mutually reinforcing mechanisms, indicating the need to monitor coping strategies and psychological symptoms along with glycemic control in optimizing clinical care in adolescents with type 1 diabetes. © 2010 by the American Diabetes Association.
Dirikx A.,Catholic University of Leuven |
Dirikx A.,Fund for Scientific Research Flanders |
Gelders D.,Catholic University of Leuven
Environmental Communication | Year: 2010
This article studies the relationship between the ideology of newspapers and their climate change coverage. Previous research has focused on the British press (Carvalho, 2007; Carvalho and Burgess, 2005). Our research broadens this scope to the French and Dutch media. The results show that the ideology of newspapers in the Netherlands is not related to climate change coverage, while in France the ideology of newspapers is related to some key aspects of climate change coverage, i.e., the presentation of the necessity of actions against climate change and the tone of climate change coverage. The findings suggests that ideological cultures play a role in the coverage of climate change in countries in which global warming has brought about much discussion in the political field and that are characterized by a highly competitive media landscape which is historically related to the political field. © 2010 Taylor & Francis.
Meeusen R.,Vrije Universiteit Brussel |
Roelands B.,Vrije Universiteit Brussel |
Roelands B.,Fund for Scientific Research Flanders |
Spriet L.L.,University of Guelph
Nestle Nutrition Institute Workshop Series | Year: 2013
Caffeine can improve exercise performance when it is ingested at moderate doses (3-6 mg/kg body mass). Caffeine also has an effect on the central nervous system (CNS), and it is now recognized that most of the performance-enhancing effect of caffeine is accomplished through the antagonism of the adenosine receptors, influencing the dopaminergic and other neurotransmitter systems. Adenosine and dopamine interact in the brain, and this might be one mechanism to explain how the important components of motivation (i.e. vigor, persistence and work output) and higher-order brain processes are involved in motor control. Caffeine maintains a higher dopamine concentration especially in those brain areas linked with 'attention'. Through this neurochemical interaction, caffeine improves sustained attention, vigilance, and reduces symptoms of fatigue. Other aspects that are localized in the CNS are a reduction in skeletal muscle pain and force sensation, leading to a reduction in perception of effort during exercise and therefore influencing the motivational factors to sustain effort during exercise. Because not all CNS aspects have been examined in detail, one should consider that a placebo effect may also be present. Overall, it appears that the performance-enhancing effects of caffeine reside in the brain, although more research is necessary to reveal the exact mechanisms through which the CNS effect is established. © 2013 Nestec Ltd., Vevey/S. Karger AG, Basel.
Claeys C.,IMEC |
Claeys C.,Catholic University of Leuven |
Mitard J.,IMEC |
Eneman G.,IMEC |
And 4 more authors.
Thin Solid Films | Year: 2010
The quest for higher performance of scaled down technologies resulted in the use of high-mobility substrates and strain engineering approaches. The development of advanced processing modules, based on low temperature processing and deposited (MBE, ALD, epitaxially grown, etc.) gate stacks, has triggered the interest of exploring Ge for sub 32 nm technology nodes. A comparison between Si and Ge for future microelectronics has to take into account a variety of materials, processing and performance aspects. Here special attention will be given to passivation and gate stack formation in relation to device performance, including leakage current and reliability aspects. The potential of Ge-based device structures and the monolithic integration of Ge and III-V devices on silicon are highlighted. © 2009 Elsevier B.V. All rights reserved.
PubMed | Fund for Scientific Research Flanders, Deakin University and Vrije Universiteit Brussel
Type: Journal Article | Journal: Journal of science and medicine in sport | Year: 2016
To assess whether associations between neighbourhood environmental features and frequency of childrens active trips per week are moderated by frequency of parental accompaniment when walking/cycling.Cross-sectional surveyChildren aged 10-12 years (n=677) were recruited from 19 schools in Melbourne, Australia. Parents reported the number of walking/cycling trips/week usually made by their child to eight local destinations. Environmental variables (i.e. number of cul-de-sacs, intersections, public open spaces (POS) defined as reserves or parks, sport and recreation POS, sport options, population density, length of busy roads and length of walking/cycling tracks) within an 800m buffer around participants homes were objectively assessed with a Geographic Information System. Associations between neighbourhood features and frequency of active trips were assessed using multilevel linear regressions. Moderating effects of regular parental accompaniment when walking/cycling were examined.Parental co-participation in walking and cycling was positively associated with frequency of overall walking/cycling trips. Number of intersections, sport and recreation POS, sport options and population density were positively associated with walking/cycling trips. Only one significant interaction was found; a positive association was found between intersection density and walking/cycling trips among children whose parents did not cycle with them while it was not associated among others.Building supporting and safe neighbourhood environments is needed to support childrens active travel behaviours to improve real and perceived safety concerns and provide relevant infrastructure and destinations, regardless of whether or not parents accompany children during walking and cycling. Although little evidence of moderation was found, future research should include co-participation in a broader range of walking behaviours.