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See detailChanges in the development of the winter-spring phytoplankton bloom in the Bay of Calvi (NW Mediterranean) over the last two decades: a response to changing climate?
Goffart, Anne ULg; Hecq, Jean-Henri ULg; Legendre, Louis

in Marine Ecology. Progress Series (2002), 236

The development of the winter-spring phytoplankton bloom was investigated in the Bay of Calvi (Corsica, Ligurian Sea, northwestern Mediterranean) in 1979, 1986, 1988, 1997 and 1998. A drastic reduction of ... [more ▼]

The development of the winter-spring phytoplankton bloom was investigated in the Bay of Calvi (Corsica, Ligurian Sea, northwestern Mediterranean) in 1979, 1986, 1988, 1997 and 1998. A drastic reduction of phytoplankton biomass was evidenced over the last 2 decades, in relation to long-term changes in climatic and environmental conditions. Between 1979 and 1998, the monthly averaged chlorophyll a concentrations at 1 m decreased by about 80% during February, March and April. Simultaneously, major changes to hydrodynamic conditions include warmer water, overall decrease of salinity at 10 m depth, longer periods of bright sunshine and lower wind stress, The changes in environmental conditions were large enough to affect the vertical stability of the water column during the winter-spring period and to reduce nutrient replenishment of the surface layer prior to the usual period of phytoplankton growth. Until 1986, the main factor driving nutrient replenishment was the winter upward mixing of nutrient-rich deep waters, while the progressive reduction of mixing from 1988 induced nutrient limitation of surface waters in the last decade. The following hypotheses on changes in the development of the winter-spring phytoplankton bloom are made: (1) Until 1986, phytoplankton peaks took place in relatively high-nutrient waters and were diatom-dominated. (2) Between 1986 and 1988, decreasing Si availability led to Si limitation which caused a reduction in diatom abundance. This resulted in the disappearance of the diatom-dominated pulses and in lower phytoplankton biomass and was accompanied by a shift toward non-siliceous phytoplankton. (3) In 1988, 1997 and 1998, decreasing nitrate availability led to nitrate limitation, thus explaining the progressive reduction in non-siliceous phytoplankton biomass. Other, associated changes in benthos assemblages and ichthyofauna are documented. The conclusions from the Bay of Calvi are extended to the whole western Corsican coast. This confirms that the Mediterranean reacts rapidly to external perturbations, which are driven by climate change in that particular area. [less ▲]

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See detailChanges in the distribution of carabid beetles in Belgium revisited: Have we halted the diversity loss?
Desender, K.; Dekoninck, W.; Dufrêne, Marc ULg et al

in Biological Conservation (2010), 143(6), 1549-1557

Twenty years ago, Desender and Turin (1989) analysed the changes in the composition of carabid beetles in four NW European countries between the periods <1950 and 1950-1985. Recently, a new distribution ... [more ▼]

Twenty years ago, Desender and Turin (1989) analysed the changes in the composition of carabid beetles in four NW European countries between the periods <1950 and 1950-1985. Recently, a new distribution atlas of carabid beetles in Belgium was compiled using data collected during the period 1986-2008. In the light of the Countdown2010 target of halting the loss of biodiversity, we used these new data to test whether or not previously observed trends were altered. Since 1950, 46 species were no longer recorded in Belgium and seven species were added to the Belgian fauna. By relating the changes in distribution area to ecological and life history traits as well as to conservation priorities of the species, we examined which species characteristics were associated with the strongest changes in distribution. Comparing the period before 1950 with the period 1950-1985 showed that species from nutrient-poor dry biotopes and heathlands, threatened, rare and big species declined. Generalists, non-threatened species, species with a pan-European distribution range, species in the centre of their distribution range and common species, on the other hand, increased. From the period 1950-1985 to 1986-2008, mainly macropterous species, both rare and very common species and big species decreased, while generalists, dimorphic species, species with a pan-European distribution range and species that were already common in the second period increased. For the conservation of carabid beetles in a strongly industrialised and highly fragmented NW European landscape, we propose actions on two levels: first, the protection and adequate management of high quality biotopes, especially nutrient-poor grasslands and heathlands, in large core areas for specialist species and second, the creation and/or restoration of a 'matrix' that facilitates the exchange of individuals between core areas for the conservation of both generalist and specialist species. © 2010 Elsevier Ltd. [less ▲]

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See detailChanges in the distribution of type IV collagen, laminin, proteoglycan, and fibronectin during mouse tooth development
Thesleff, I.; Barrach, H. J.; Foidart, Jean-Michel ULg et al

in Developmental Biology (1981), 81(1), 182-92

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See detailChanges in the Distribution Pattern of Galectin-1 and Galectin-3 in Human Placenta Correlates with the Differentiation Pathways of Trophoblasts
Maquoi, Erik ULg; van den Brule, F. A.; Castronovo, Vincenzo ULg et al

in Placenta (1997), 18(5-6, Jul-Aug), 433-9

Human placentation is a complex biological phenomenon that results from precisely regulated interactions between cells and the extracellular matrix. Galectin- 1 and galectin-3 belong to a newly defined ... [more ▼]

Human placentation is a complex biological phenomenon that results from precisely regulated interactions between cells and the extracellular matrix. Galectin- 1 and galectin-3 belong to a newly defined family of galactose-binding lectins that can bind several glycoconjugates such as the basement membrane glycoprotein laminin, and are involved in many biological events including cell adhesion. In this study, the expression of these two galectins in first and third trimester normal human placenta was examined using single and double immunohistochemical staining and specific antibodies for galectins and cytokeratins. Galectin-3 was detected in all trophoblastic lineages including villous cytotrophoblasts and extravillous trophoblasts (trophoblastic cell columns, infiltrating trophoblasts, endovascular trophoblasts and placental bed giant cells). On the contrary, galectin-1 distribution was restricted to endometrium. A reduction of galectin-3 expression was observed from the villous trophoblasts to the trophoblastic cell columns. This pattern correlated with the switch from a proliferative to a migratory phenotype. Galectin-1 and galectin-3 were both detected in maternal decidual cells. Our data demonstrate a specific pattern of galectin-1 and galectin-3 expression in trophoblastic tissue, and suggest these lectins could contribute to cell-cell and cell matrix interactions of trophoblast during placentation. [less ▲]

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See detailChanges in the enantiomeric distribution of selected volatile constituents of Mentha pulegium L. powders caused by hot water treatment
Brokl, Michal ULg; Flores, G.; Blanch, G. P. et al

in Journal of Agricultural and Food Chemistry (2006), 54(23), 8836-8841

The variation, in general, of the composition of the aromatic fraction and, in particular, of the enantiomeric composition of certain chiral volatile compounds of commercial Mentha pulegium L. powders ... [more ▼]

The variation, in general, of the composition of the aromatic fraction and, in particular, of the enantiomeric composition of certain chiral volatile compounds of commercial Mentha pulegium L. powders caused by boiling water was evaluated. A comparison between the volatile profile of the studied herbs demonstrated that most M. pulegium L. samples contained high proportions of Mentha piperita L., even when this information was not specified on the label. Likewise, substantial changes in the volatile fraction of the infusions with respect to the composition of the original plant used in their preparation were found. The enantiomeric composition of some chiral compounds of the dried plant material, particularly limonene, was modified by adding hot water, whereas others were kept invariable. The results shown in this work reflect the need for the control of the composition of commercial powders and brews of M. pulegium L. to ensure their correct application. [less ▲]

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See detailChanges In The Hypophyseal-Gonadal Axis During The Onset Of Puberty In Young Bulls
Renaville, Robert ULg; Devolder, A.; Massart, Serge et al

in Journal of Reproduction and Fertility (1993), 99(2),

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See detailChanges in the isoflavone concentration in red clover (Trifolium pratense L.) during ensiling and storage in laboratory-scale silos
Daems, Frédéric ULg; Decruyenaere, Virginie ULg; Agneessens, Richard et al

in Animal Feed Science & Technology (2016)

Isoflavones constitute one of the most common categories of nonsteroidal estrogen-like substances belonging to the broad group of phytoestrogens. The highest concentrations in the plant kingdom are found ... [more ▼]

Isoflavones constitute one of the most common categories of nonsteroidal estrogen-like substances belonging to the broad group of phytoestrogens. The highest concentrations in the plant kingdom are found in the Fabaceae family. They have become a focus of research because of their estrogenic or anti-estrogenic effect and potential impact on human health. In recent years, several studies have focused on the impact of biotic and abiotic factors and farming management on the isoflavone concentration in plants and their impact on the composition of cow’s milk. Nevertheless, knowledge about the effect of the ensiling process on isoflavone concentration remains limited. The objective of this work was to study the evolution of the concentrations of four compounds (daidzein, formononetin, genistein and biochanin A) in red clover (Trifolium pratense L.) ensiled at harvest. The impact of the field-drying process was also assessed. The plant material was ensiled in laboratory scale silos using vacuum-packed plastic bags and stored over a 6-month period. The quality of the silages was checked throughout the experiment by determining the pH, lactic acid concentration, volatile fatty acids, crude proteins, cellulose and other chemical characteristics. The isoflavone concentration in fresh plant material was 2050, 1766, 306 and 127 µg/g DM for formononetin, biochanin A, genistein and daidzein, respectively. After 4 days of drying in the field, no significant change in isoflavone concentration was found, except for daidzein, which increased twofold. The laboratory-scale silos experiment, however, showed a decrease in isoflavone concentration during the first 2 weeks, followed by stabilization over the 5 remaining months. The concentrations fell by 26, 39, 66 and 73% for daidzein, genistein, biochanin A and formononetin, respectively. Animals fed with silage would therefore absorb fewer isoflavones than those fed with fresh plant material or hay. [less ▲]

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See detailChanges in the moss layer after liming in a Norway spruce (Picea abies (L.) Karst.) stand of Eastern Belgium
Dulière, J.-F.; De Bruyn, R.; Malaisse, François ULg

in Forest Ecology & Management (2000), 136(1-3), 97-105

The impact of dolomite lime (5 t ha -1) on the moss layer was investigated in a Belgian Norway spruce (Picea abies (L.) Karst.) forest. Bryophytes reacted rapidly, showing a decrease in frequency, cover ... [more ▼]

The impact of dolomite lime (5 t ha -1) on the moss layer was investigated in a Belgian Norway spruce (Picea abies (L.) Karst.) forest. Bryophytes reacted rapidly, showing a decrease in frequency, cover and biomass of acidophilous dominant Dicranaceae species. Some neutrophilous competitive or stress tolerant species were spreading out and some ruderals appeared. The reaction of the dominant species coverage to different liming rates was also considered. Results showed that the negative effect was more pronounced than higher dolomite doses were. (C) 2000 Elsevier Science B.V. [less ▲]

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See detailChanges in the PhD Education Policy in Spain: an Institutional Approach
Aliaga Isla, Rocio ULg; Rojas de Franciso, Laura; Lopez, Jordi et al

Conference (2014)

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See detailChanges in the renal and maternal utero-placental arteries in pregnancies complicated by hypertension
Foidart, Jean-Michel ULg; Hustin, J.; Lambotte, R. et al

in Revue Médicale de Liège (1983), 38(12), 519-36

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See detailChanges in the room-temperature emission spectrum of chlorophyll during fast and slow phases of the Kautsky effect in intact leaves
Franck, Fabrice ULg; Dewez, D.; Popovic, R.

in Photochemistry & Photobiology (2005), 81(2, Mar-Apr), 431-436

Changes in the room-temperature emission spectrum of chlorophyll (Chl) were analyzed using fast diode-array recordings during the Kautsky effect in mature and in greening barley leaves. In mature leaves ... [more ▼]

Changes in the room-temperature emission spectrum of chlorophyll (Chl) were analyzed using fast diode-array recordings during the Kautsky effect in mature and in greening barley leaves. In mature leaves, the comparison of F-O (basal level of fluorescence yield at transient O) and F-M (maximum level of fluorescence yield at transient M) spectra showed that the relative amplitude of total variable fluorescence was maximal for the 684 nm Photosystem II (PSII) band and minimal for the 725 nm Photosystem I band. During the increase from F-O to F-M, a progressive redshift of the spectrum of variable fluorescence occurred. This shift reflected the different fluorescence rise kinetics of different layers of chloroplasts inside the leaf. This was verified by simulating the effect of screening on the emission spectrum of isolated chloroplasts and by experiments on greening leaves with low Chl content. In addition, experiments performed at different greening stages showed that the presence of uncoupled Chl at early-greening stages and light-harvesting complex II (LHCII) at later stages have detectable but minor effects on the shape of room-temperature emission spectra. When strong actinic light was applied to mature green leaves, the slow fluorescence yield, which declined from F-M to FT (steady-state level of fluorescence yield at transient T), was accompanied by a slight redshift of the 684 nm PSII band because of nonphotochemical quenching of short-wavelength-emitting Chl ascribed to LHCII. [less ▲]

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See detailChanges in the structure and the composition of microtubules within supporting cells of the organ of hearing during development.
Renauld, Justine ULg; Freeman, Stephen ULg; Thelen, Nicolas ULg et al

Poster (2016)

The auditory organ is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. These ... [more ▼]

The auditory organ is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. These cells are supported by supporting cells which contain up to 3000 microtubules and are formed by 15protofilaments (15pf) instead of the canonical 13, a unique fact among vertebrates. It was shown that a β-tubulin isoform can specify the microtubule architecture, such as the expression of the Moth β2 in the Drosophila testes imposed the 16pf structure on the corresponding subset of Drosophila microtubules, which normally contain 13pf. To determine the role of these tubulins in the auditory organ and their possible involvement in the formation of the unusual 15pf microtubules of supporting cells, we studied the spatiotemporal localization of five -tubulin isotypes (β1 to 5) as well as acetyl-α-tubulin within the hearing organ during development in rodents. By using confocal microscopy, we showed that with the exception of the β3-tubulin isoform that was specific to nerve fibres, all the different β-tubulin isoforms and acetyl-α-tubulin were mainly present in the supporting cells. Contrary to β1-4-tubulins, we also found that the β5-tubulin isoform appeared only at a key stage of the postnatal development. By using transmission electron microscopy, we examined the fine structure of microtubules at an early and a late postnatal stage. Our TEM study indicated that these cells are composed by 13pf microtubules at P2, but by 15pf microtubules at P25. We revealed further that this developmental stage coincide with the formation of two separate bundles of microtubules from a unique one in these supporting cells. In conclusion, the architecture and composition of microtubules present in the supporting cells change during development of the organ of Corti. Further experiments are now required to determine if these changes are related to the appearance of β5-tubulin. [less ▲]

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See detailChanges in the structure and the symptoms of the osteoarthritis knee and prediction of future knee replacement over an 8-year follow-up period
Bruyère, Olivier ULg; Cooper, Cyrus; Pavelka, Karel et al

in Osteoporosis International (2013, April), 24(Suppl.1), 209

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See detailChanges in the transcriptional profile in response to overexpression of the osteopontin-c splice isoform in ovarian (OvCar-3) and prostate (PC-3) cancer cell lines.
Tilli, Tatiana M.; Bellahcene, Akeila ULg; Castronovo, Vincenzo ULg et al

in BMC cancer (2014), 14

BACKGROUND: Especially in human tumor cells, the osteopontin (OPN) primary transcript is subject to alternative splicing, generating three isoforms termed OPNa, OPNb and OPNc. We previously demonstrated ... [more ▼]

BACKGROUND: Especially in human tumor cells, the osteopontin (OPN) primary transcript is subject to alternative splicing, generating three isoforms termed OPNa, OPNb and OPNc. We previously demonstrated that the OPNc splice variant activates several aspects of the progression of ovarian and prostate cancers. The goal of the present study was to develop cell line models to determine the impact of OPNc overexpression on main cancer signaling pathways and thus obtain insights into the mechanisms of OPNc pro-tumorigenic roles. METHODS: Human ovarian and prostate cancer cell lines, OvCar-3 and PC-3 cells, respectively, were stably transfected to overexpress OPNc. Transcriptomic profiling was performed on these cells and compared to controls, to identify OPNc overexpression-dependent changes in gene expression levels and pathways by qRT-PCR analyses. RESULTS: Among 84 genes tested by using a multiplex real-time PCR Cancer Pathway Array approach, 34 and 16, respectively, were differentially expressed between OvCar-3 and PC-3 OPNc-overexpressing cells in relation to control clones. Differentially expressed genes are included in all main hallmarks of cancer, and several interacting proteins have been identified using an interactome network analysis. Based on marked up-regulation of Vegfa transcript in response to OPNc overexpression, we partially validated the array data by demonstrating that conditioned medium (CM) secreted from OvCar-3 and PC-3 OPNc-overexpressing cells significantly induced endothelial cell adhesion, proliferation and migration, compared to CM secreted from control cells. CONCLUSIONS: Overall, the present study elucidated transcriptional changes of OvCar-3 and PC-3 cancer cell lines in response to OPNc overexpression, which provides an assessment for predicting the molecular mechanisms by which this splice variant promotes tumor progression features. [less ▲]

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See detailChanges in the Western Boundary Undercurrent outflow since the Last Glacial Maximum, from smectite/illite ratios in deep Labrador Sea sediments
Fagel, Nathalie ULg; Hillaire-Marcel; Robert, Christian

in Paleoceanography (1997), 12(1), 79-96

High-resolution mineralogical studies were performed on late glacial and deglacial sediments from two deep piston cores from the Labrador Sea, located at the inlet (SW Greenland Rise) and outlet (Labrador ... [more ▼]

High-resolution mineralogical studies were performed on late glacial and deglacial sediments from two deep piston cores from the Labrador Sea, located at the inlet (SW Greenland Rise) and outlet (Labrador Rise) of the Western Boundary Undercurrent (WBUC) gyre. At the two sites, smectites transported from the eastern Iceland and Irminger basins by the WBUC are observed. Clay mineral changes are used as proxies for the paleointensity reconstruction of the WBUC. On the Greenland Rise, a clay mineral index (smectite/illite (S/I) ratio) is defined. A S/I ratio of similar to 1 characterized the Last Glacial Maximum. It increased after similar to 17 ka, and reached a maximum value of 4 during the early Holocene, The mineralogical changes are gradual and do not show any reversal during the Younger Dryas, This pattern, which is confirmed by first-order estimations of smectite and illite fluxes, suggests gradually increasing sedimentary fluxes and WBUC intensity since the Last Glacial Maximum, A peak in the velocity of the WBUC at similar to 9 ka, as recorded by clay assemblages, is consistent with other regional studies based on pollen, foraminifera, or grain-size measurements, A massive dilution of smectites by illite and chlorite (S/I approximate to 3) occurs at similar to 8.5 ka. It corresponds to a period of rapid sediment accumulation and reflects an intensified illite-rich detrital supply by meltwaters from the southern Greenland Ice Margin. On the Labrador Rise, the smectite content varies between 20 and 60% with no obvious trend through time. The mineralogical composition is strongly influenced by ice-rafted deposition and by the abundance of fast deposit units (cf, Heinrich layers in the North Atlantic) which contain abundant detrital carbonates spilled-over from the North-West Atlantic Mid-Ocean Channel. In such layers, smectites are present but are diluted by the addition of illites, chlorites, and kaolinites. This provides evidence for a discrete and continuous WBUC supply of fine particles from the Irminger and Iceland Basins as far as the southeastern part of the Labrador Basin, Early deglacial smectite-rich layers (up to 60%) are also observed at this site, They indicate an increase in the outflow of the WBUC at similar to 13.5 ka, (Bolling-Allerod), as previously reported from grain size or foraminiferal assemblage studies. [less ▲]

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See detailChanges in trace elements during lactation in a marine top predator, the grey seal
Habran, Sarah ULg; Pomeroy, P; Debier, C et al

in Aquatic Toxicology (2013), 126

Lactation in pinnipeds represents the most significant cost to mothers during the reproductive cycle. Dynamics of trace elements and their mobilization associated with energy reserves during such an ... [more ▼]

Lactation in pinnipeds represents the most significant cost to mothers during the reproductive cycle. Dynamics of trace elements and their mobilization associated with energy reserves during such an intense physiological process remains poorly understood in marine mammals. The changes in tissue concentrations of 11 elements (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) were investigated in a longitudinal study during the lactation period and during the post-weaning fast period. Blood, milk, blubber, and hair samples were collected sequentially from 21 mother-pup pairs of grey seals (Halichoerus grypus) from the Isle of May in Scotland. Maternal transfer through the milk was observed for all trace elements, except for Cd. As an indicator of the placental transfer, levels in pup lanugo (natal coat) revealed also the existence of maternal transfer and accumulation of all assayed trace elements during the foetal development. The placental and mammary barriers against non-essential metal transfer to offspring appear to be absent or weak in grey seals. Examining the contamination levels showed that this grey seal population seems more highly exposed to Pb than other phocid populations (2.2 mg/kg dw of grey seal hair). In contrast, blood and hair levels reflected a lower Hg exposure in grey seals from the Isle of May than in harbour seals from the southeastern North Sea. This study also showed that trace element concentrations in blood and blubber could change rapidly over the lactation period. Such physiological processes must be considered carefully during biomonitoring of trace elements, and potential impacts that rapid fluctuations in concentrations can exert on seal health should be further investigated. [less ▲]

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See detailChanges in Travel Behavior in Response to Weather Conditions: Do Type of Weather and Trip Purpose Matter
Cools, Mario ULg; Moons, Elke; Creemers, Lieve et al

in Transportation Research Record: Journal of the Transportation Research Board (2010), 2157

Weather can influence travel demand, traffic flow, and traffic safety. A hypothesis—the type of weather determined the likelihood of a change in travel behavior, and changes in travel behavior because of ... [more ▼]

Weather can influence travel demand, traffic flow, and traffic safety. A hypothesis—the type of weather determined the likelihood of a change in travel behavior, and changes in travel behavior because of weather conditions depended on trip purpose—was assayed. A stated adaptation study was conducted in Flanders (the Dutch-speaking region of Belgium). A survey, completed by 586 respondents, was administered both on the Internet and as a traditional paper-and-pencil questionnaire. To ensure optimal correspondence between the survey sample composition and the Flemish population, observations in the sample were weighted. To test the main hypotheses, Pearson chi-square independence tests were performed. Results from both the descriptive analysis and the independence tests confirm that the type of weather matters and that changes in travel behavior in response to these weather conditions are highly dependent on trip purpose. This dependence of behavioral adjustments on trip purpose provides policy makers with a deeper understanding of how weather conditions affect traffic. Further generalizations of the findings are possible by shifting the scope toward revealed travel behavior. Triangulation of both stated and revealed travel behavior on the one hand and traffic intensities on the other hand is a key challenge for further research. [less ▲]

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See detailChanges in Travel Behavior in Response to Weather Conditions: Do Type of Weather and Trip Purpose Matter
Cools, Mario ULg; Moons, Elke; Creemers, Lieve et al

in Proceedings of the 89th Annual Meeting of the Transportation Research Board (DVD-ROM) (2010)

Weather events can affect traffic in various ways; it can influence travel demand, traffic flows and traffic safety. This paper focuses on the impact of weather conditions on travel demand. The main ... [more ▼]

Weather events can affect traffic in various ways; it can influence travel demand, traffic flows and traffic safety. This paper focuses on the impact of weather conditions on travel demand. The main objectives of this paper are to test the hypothesis that the type of weather determines the likelihood of a change in travel behavior and to assay whether the changes in travel behavior due to weather conditions are dependent on the trip purpose. To this end, a stated adaptation study was conducted in Flanders (Dutch speaking region of Belgium). In total 586 respondents completed the survey, which was administered both on the Internet and via a traditional paper and-pencil questionnaire. To ensure an optimal correspondence between the survey sample composition and the Flemish population, the observations in the sample are weighted. To test the main hypotheses Pearson chi-square independence tests will be performed. Both the results from the descriptive analysis and the independence tests confirm that the type of weather matters, and that the changes in travel behavior in response to these weather conditions are highly dependent on the trip purpose. This dependence of behavioral adjustments on trip purposes provides policy makers with a deeper understanding of how weather conditions affect traffic. Further generalizations of the findings are possible by shifting the scope towards revealed travel behavior. Triangulation of both stated and revealed travel behavior on the one hand, and traffic intensities on the other hand, is certainly a key challenge for further research. [less ▲]

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See detailChanges in visual-evoked potential habituation induced by hyperventilation in migraine.
Coppola, G.; Curra, A.; Sava, Simona ULg et al

in Journal of Headache & Pain (2010)

Hyperventilation is often associated with stress, an established trigger factor for migraine. Between attacks, migraine is associated with a deficit in habituation to visual-evoked potentials (VEP) that ... [more ▼]

Hyperventilation is often associated with stress, an established trigger factor for migraine. Between attacks, migraine is associated with a deficit in habituation to visual-evoked potentials (VEP) that worsens just before the attack. Hyperventilation slows electroencephalographic (EEG) activity and decreases the functional response in the occipital cortex during visual stimulation. The neural mechanisms underlying deficient-evoked potential habituation in migraineurs remain unclear. To find out whether hyperventilation alters VEP habituation, we recorded VEPs before and after experimentally induced hyperventilation lasting 3 min in 18 healthy subjects and 18 migraine patients between attacks. We measured VEP P100 amplitudes in six sequential blocks of 100 sweeps and habituation as the change in amplitude over the six blocks. In healthy subjects, hyperventilation decreased VEP amplitude in block 1 and abolished the normal VEP habituation. In migraine patients, hyperventilation further decreased the already low block 1 amplitude and worsened the interictal habituation deficit. Hyperventilation worsens the habituation deficit in migraineurs possibly by increasing dysrhythmia in the brainstem-thalamo-cortical network. [less ▲]

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