9 results on '"Timmermans, W."'
Search Results
2. Stress and excitatory synapses: From health to disease.
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Timmermans, W., Xiong, H., Hoogenraad, C.C., and Krugers, H.J.
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PSYCHOLOGICAL stress , *SYNAPSES , *NEURAL transmission , *MEMORY , *DENDRITIC cells , *DEVELOPMENTAL neurobiology - Abstract
Highlights: [•] Stress can result in highly adaptive responses but is also an important risk factor for disease. [•] Acute stress rapidly enhances excitatory synaptic transmission and promotes learning and memory processes. [•] Chronic stress reduces excitatory synaptic transmission and learning and memory. [•] Early life experience has long-lasting effects on excitatory synaptic transmission and dendritic complexity. [ABSTRACT FROM AUTHOR]
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- 2013
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3. Accounting for atmospheric boundary layer variability on flux estimation from RS observations.
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Timmermans, W. J., Bertoldi, G., Albertson, J. D., Olioso, A., Su, Z., and Gieske, A. S. M.
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ATMOSPHERIC boundary layer , *SOIL management , *VEGETATION management , *HEAT flux , *SIMULATION methods & models , *ATMOSPHERE - Abstract
A Large Eddy Simulation (LES) model is coupled to a remote-sensing-based SVAT that accounts for soil and vegetation in order to study the feedback effects between surface state and spatial variability in fluxes, through the induction of spatial variability in the lower atmosphere. As such, this study focuses on sensible heat flux exchange. The simulations indicated that changes are introduced to the flux distributions mainly at higher surface temperatures. A scale-dependent method is presented to account for feedback effects. This showed the most significant correlation between surface and air temperature at scales from 500 to 1000 m and modulated the spatial variance of sensible heat flux. This suggests that feedback effects act to limit the spatial variability in fluxes, and ignoring them will cause the largest errors at the extremes. [ABSTRACT FROM AUTHOR]
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- 2008
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4. Quantification of land-atmosphere exchanges of water, energy and carbon dioxide in space and time over the heterogeneous Barrax site.
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Su, Z., Timmermans, W., Gieske, A., Jia, L., Elbers, J. A., Olioso, A., Timmermans, J., Van Der Velde, R., Jin, X., Van Der Kwast, H., Nerry, F., Sabol, D., Sobrino, J. A., Moreno, J., and Bianchi, R.
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ATMOSPHERE , *CARBON dioxide , *WATER , *FORCE & energy , *SPACETIME , *SOIL management - Abstract
To advance our understanding of land-atmosphere exchanges of water, energy and carbon dioxide (CO2) in space and time over heterogeneous land surfaces, two intensive field campaigns were carried out at the Barrax agricultural test site in Spain during 12-21 July 2004 (SPARC 2004) and 8-14 July 2005 (SEN2FLEX 2005) involving multiple field, satellite and airborne instruments for characterizing the state of the atmosphere, the vegetation and the soil from the visible to the microwave range of the spectrum. Part of the experimental area is a core site of area 25 km2, within which numerous crops are grown, on both irrigated and dry land, alongside fields of bare soil. The campaigns were carried out in the framework of the Earth Observation Envelope Programme of the European Space Agency (ESA) with the aim of supporting geophysical algorithm development, calibration/validation and the simulation of future spaceborne Earth Observation missions. Both campaigns were also contributions to the EU 6FP EAGLE Project. The emphasis of this contribution is on the in situ measurements of land-atmosphere exchanges of water, energy and CO2 as well as the thermal dynamic states of the atmosphere, the soil and the vegetation. Preliminary analysis and interpretation of the measurements are presented. These two data sets are open to the scientific community for collaborative investigations. [ABSTRACT FROM AUTHOR]
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- 2008
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5. Cellular localization of metabotropic glutamate receptors in cortical tubers and subependymal giant cell tumors of tuberous sclerosis complex
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Boer, K., Troost, D., Timmermans, W., Gorter, J.A., Spliet, W.G.M., Nellist, M., Jansen, F., and Aronica, E.
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TUBEROUS sclerosis , *CELL receptors , *GLUTAMIC acid , *BRAIN diseases , *EPILEPSY , *FRAGILE X syndrome , *TUMOR growth , *IMMUNOCYTOCHEMISTRY - Abstract
Abstract: Tuberous sclerosis complex (TSC) is an autosomal dominant disorder associated with cortical malformations (cortical tubers) and the development of glial tumors (subependymal giant-cell tumors, SGCTs). Expression of metabotropic glutamate receptor (mGluR) subtypes is developmentally regulated and several studies suggest an involvement of mGluR-mediated glutamate signaling in the regulation of proliferation and survival of neural stem-progenitor cells, as well as in the control of tumor growth. In the present study, we have investigated the expression and cell-specific distribution of group I (mGluR1, mGluR5), group II (mGluR2/3) and group III (mGluR4 and mGluR8) mGluR subtypes in human TSC specimens of both cortical tubers and SGCTs, using immunocytochemistry. Strong group I mGluR immunoreactivity (IR) was observed in the large majority of TSC specimens in dysplastic neurons and in giant cells within cortical tubers, as well as in tumor cells within SGCTs. In particular mGluR5 appeared to be most frequently expressed, whereas mGluR1α was detected in a subpopulation of neurons and giant cells. Cells expressing mGluR1α and mGluR5, demonstrate IR for phospho-S6 ribosomal protein (PS6), which is a marker of the mammalian target of rapamycin (mTOR) pathway activation. Group II and particularly group III mGluR IR was less frequently observed than group I mGluRs in dysplastic neurons and giant cells of tubers and tumor cells of SGCTs. Reactive astrocytes were mainly stained with mGluR5 and mGluR2/3. These findings expand our knowledge concerning the cellular phenotype in cortical tubers and in SGCTs and highlight the role of group I mGluRs as important mediators of glutamate signaling in TSC brain lesions. Individual mGluR subtypes may represent potential pharmacological targets for the treatment of the neurological manifestations associated with TSC brain lesions. [Copyright &y& Elsevier]
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- 2008
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6. Analysis of current validation practices in Europe for space-based climate data records of essential climate variables.
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Zeng, Y., Su, Z., Calvet, J.-C., Manninen, T., Swinnen, E., Schulz, J., Roebeling, R., Poli, P., Tan, D., Riihelä, A., Tanis, C.-M., Arslan, A.-N., Obregon, A., Kaiser-Weiss, A., John, V.O., Timmermans, W., Timmermans, J., Kaspar, F., Gregow, H., and Barbu, A.-L.
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CLIMATE change , *REMOTE-sensing images , *DATA analysis , *INFORMATION processing - Abstract
The Climate Data Records (CDRs) of Essential Climate Variables (ECVs) that are based on satellite observations need to be precisely described. In particular, when these products are delivered to end-users, the error characteristics information and how this information is obtained (e.g., through a validation process) need to be documented. Such validation information is intended to help end-users understanding to what extent the product is suitable for their specific applications. Based on how different European initiatives approached the validation of CDR and ECV products, we reviewed several aspects of the current validation practices. Based on the analysis of current practices, essentials of validation are discussed. A generic validation process is subsequently proposed, together with a quality indicator. [ABSTRACT FROM AUTHOR]
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- 2015
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7. How peri-urban areas can strengthen animal populations within cities: A modeling approach
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Snep, R.P.H., Opdam, P.F.M., Baveco, J.M., WallisDeVries, M.F., Timmermans, W., Kwak, R.G.M., and Kuypers, V.
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HABITATS , *ANIMAL ecology , *ANIMAL populations , *URBAN ecology - Abstract
Abstract: We explore the extent to which inner-city fauna can be enhanced by source areas in peri-urban zones as a response to a decreasing quality and size of green habitats within cities. The objectives were to get a better understanding of the interaction between animal populations of urban and peri-urban areas, and the role of urban green structures within this relationship, and to find out the extent to which peri-urban areas can contribute to urban animal populations. We illustrate the idea of peri-urban support by using a simulation model for individual animal movement, applied in a particular case-study with butterflies as model species. Results show differences in accessibility of inner-city areas between model butterfly species that differ in mobility. The impact of peri-urban individuals on populations of inner-city habitats differed among several peri-urban source-scenarios: the enlargement of the inner-city butterfly population by peri-urban individuals was determined as 7–36% for ‘moderate dispersers’ and 19–56% for ‘good dispersers’. Results also show that well-connected habitat patches within existing urban green structures were more likely to be visited by peri-urban individuals than isolated habitat patches. We conclude that peri-urban nature areas, if large enough, can have a potentially positive influence on the presence of fauna in inner-city neighborhoods. In addition, results suggest that connectivity between inner-city and peri-urban habitat patches enhances contribution of peri-urban migrants to inner-city populations. By providing a range of different habitats, from inner-city up to peri-urban area, moderately mobile habitat specialists could better compete against the small set of successful habitat generalists that are increasing in urban environments all over the world. [Copyright &y& Elsevier]
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- 2006
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8. Surface energy fluxes with the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) at the Iowa 2002 SMACEX site (USA)
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French, A.N., Jacob, F., Anderson, M.C., Kustas, W.P., Timmermans, W., Gieske, A., Su, Z., Su, H., McCabe, M.F., Li, F., Prueger, J., and Brunsell, N.
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RADIOMETERS , *THERMAL analysis , *EMISSION exposure , *SURFACE chemistry - Abstract
Abstract: Accurate estimation of surface energy fluxes from space at high spatial resolution has the potential to improve prediction of the impact of land-use changes on the local environment and to provide a means to assess local crop conditions. To achieve this goal, a combination of physically based surface flux models and high-quality remote-sensing data are needed. Data from the ASTER sensor are particularly well-suited to the task, as it collects high spatial resolution (15–90 m) images in visible, near-infrared, and thermal infrared bands. Data in these bands yield surface temperature, vegetation cover density, and land-use types, all critical inputs to surface energy balance models for assessing local environmental conditions. ASTER is currently the only satellite sensor collecting multispectral thermal infrared images, a capability allowing unprecedented surface temperature estimation accuracy for a variety of surface cover types. Availability of ASTER data to study surface energy fluxes allows direct comparisons against ground measurements and facilitates detection of modeling limitations, both possible because of ASTER''s higher spatial resolution. Surface energy flux retrieval from ASTER is demonstrated using data collected over an experimental site in central Iowa, USA, in the framework of the Soil Moisture Atmosphere Coupling Experiment (SMACEX). This experiment took place during the summer of 2002 in a study of heterogeneous agricultural croplands. Two different flux estimation approaches, designed to account for the spatial variability, are considered: the Two-Source Energy Balance model (TSEB) and the Surface Energy Balance Algorithm or Land model (SEBAL). ASTER data are shown to have spatial and spectral resolution sufficient to derive surface variables required as inputs for physically based energy balance modeling. Comparison of flux model results against each other and against ground based measurements was promising, with flux values commonly agreeing within ∼50 W m−2. Both TSEB and SEBAL showed systematic agreement and responded to spatially varying surface temperatures and vegetation densities. Direct comparison against ground Eddy Covariance data suggests that the TSEB approach is helpful over sparsely vegetated terrain. [Copyright &y& Elsevier]
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- 2005
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9. Corrigendum to “Surface energy fluxes with the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) at the Iowa 2002 SMACEX site (USA)” [Remote Sensing of Environment 2005 99/1–2;55–65]
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French, A.N., Jacob, F., Anderson, M.C., Kustas, W.P., Timmermans, W., Gieske, A., Su, Z., Su, H., McCabe, M.F., Li, F., Prueger, J., and Brunsell, N.
- Published
- 2005
- Full Text
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