318 research outputs found
Influence of variable substrate geometry on wettability and cellular responses
No full textIn this report, we evaluate the impact of a systematic change to the extracellular environment on cell morphology and functionality by combining the inherent properties of biocompatible polymers such as polydimethylsiloxane and polycaprolactone with a specific surface response. By microstructuring pillars and pits on the substrates, varying spacing and height of the structures, we investigate the role of topography in fibroblast cell adhesion and viability. The change of wetting behaviour was tailored and evaluated in terms of contact angle measurements. It was shown that the range of micro-scale physical cues at the interface between the cells and the surrounding environment affects cell shape and migrations, indicating a tendency to respond differently to higher features of the micro-scale. We found that surface topography seems dominant over material wettability, fibroblasts responded to variations in topography by altering morphology and migrating along the direction of spacing among the features biased by the height of structures and not by the material. It is therefore possible to selectively influence either cell adhesion or morphology by choosing adequate topography of the surface. This work can impact in the design of biomaterials and can be applied to implanted biomedical devices, tissue engineering scaffolds and lab on chip devices
An Author Writing to Remember and Celebrate Black Children
No full textWith an undergraduate degree in sociology from Morgan State University (Baltimore, MD) and a master’s degree in Library Science from the Catholic University of America (Washington, DC), Sharon Bell Mathis is a librarian and a multiple award-winning children’s and young adult book author [...
Superhydrophobicity and Superhydrophilicy of Regular Nanopatterns
No full textThe hydrophilicity, hydrophobicity, and sliding behaviour of water droplets on nanoasperities of controlled dimensions were investigated experimentally. We show that the "hemi-wicking"theory for hydrophilic SiO2 samples successfully predicts the experimental advancing angles and that the same patterns, after silanization, become superhydrophobic in agreement with the Cassie-Baxter and Wenzel theories. Our model tophographies have the same dimensional scale of some naturally occurring structures that exhibit similar wetting properties. Our results confirm that a forest of hydrophilic/hydrophobic slender pillars is the most effective superwettable/water-repellent configuration. It is shown that the shape and curvature of the edges of the aspertieis play an important role in determining the advancing angles
Air-trapping on biocompatible nanopatterns
No full textThe occurrence of air-trapping inside poly-eta-caprolactone nanopits was investigated by measuring the contact angles of water droplets on a set of defined nanotopographies. It is shown that the advancing angles follow the Cassie-Baxter theory, thus revealing the presence of air bubbles inside the biodegradable nanopatterns. The importance of these observations for the definition of hydrophilicity/hydrophobicity and in the context of in vitro cell behavior is discussed
Mechanical gradient cues for guided cell motility and control of cell behavior on uniform substrates
No full textA novel method for the fabrication and the use of simple uniform poly(dimethylsiloxane) PDMS substrates for controlling cell motility by a mechanical gradient is reported. The substrate is fabricated in PDMS using soft lithography and consists of a soft membrane suspended on top of a patterned PDMS substrate. The difference in the gradient stiffness is related to the underlying pattern. It is shown experimentally that these uniform substrates can modulate the response of cell motility, thus enabling patterning on the surfaces with precise cell motility. Because of the uniformity of the substrate, cells can spread equally and a directional movement to stiffer regions is clearly observed. Varying the geometry underlying the membrane, cell patterning and movement can be quantitatively characterized. This procedure is capable of controlling cell motility with high fidelity over large substrate areas. The most significant advance embodied in this method is that it offers the use of mechanical features to control cell adhesion and not topographical or chemical variations, which has not been reported so far. This modulation of the response of cell motility will be useful for the design and fabrication of advanced planar and 3D biological assemblies suitable for applications in the field of biotechnology and for tissue-engineering purposes
The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder
No full textA key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.<br/
Pretrained Transformers of "B-spline Curve Approximation With Transformer Neural Networks" article
No full textPretrained Transformers of B-spline Curve Approximation With Transformer Neural Networks article
This dataset contains model checkpoints along with configuration and log files of trained transformer neural networks. Those networks have been trained following the methodology described in the link article. The following github repository can be used to read, test and process the data found in this dataset : bspline-curve-approximation-transformer.
The Readme file can help you understand the nature of the data to help you in treating it yourself. A recent version of Pytorch is required to load some of the data (i.e. model checkpoints and parameters).
The training logs and inference results come as csv and txt files and can be read and processed by any software of your choice.
See Readme.md for a more detailed description of files and parameters. Feel free to contact the author regarding questions/problems with the data.</p
Global and local estimates of environmental flow requirements to sustain river ecosystems are poorly correlated
No full textData repository for ‘Global and local estimates of environmental flow requirements to sustain river ecosystems are poorly correlated ‘
prepared by Mathis L. Messager ([email protected])
1. Overview and background ----------------------------------------------------------
This documentation describes the input and output data associated with the analysis presented in: Messager, M. L., Dickens, W. S. C., Eriyagama, N., Tharme, R. E., Stassen, R. (2024). Limited comparability of global and local estimates of
environmental flow requirements to sustain river ecosystems. https://doi.org/10.1088/1748-9326/ad1cb5.
Environmental flows (e-flows) are a central element of sustainable water resource management to mitigate the detrimental impacts of hydrological alteration on freshwater ecosystems and their benefits to people. Many nations strive to protect e-flows through policy, and thousands of local-scale e-flows assessments have been conducted globally, leveraging data and knowledge to quantify how much water must be provided to river ecosystems, and when, to keep them healthy. However, e-flows assessments and implementation are geographically uneven and cover a small fraction of rivers worldwide. This hinders globally consistent target-setting, monitoring and evaluation for international agreements to curb water scarcity and biodiversity loss. Therefore, dozens of models have been developed over the past two decades to estimate the e-flows requirements of rivers seamlessly across basins and administrative boundaries at a global scale.There has been little effort, however, to benchmark these models against locally derived e-flows estimates, which may limit confidence in the relevance of global estimates. The aim of this study was to assess whether current global methods reflect e-flows estimates used on the ground, by comparing global and local estimates for 1194 sites across 25 countries. We found that while global approaches broadly approximate the bulk volume of water that should be precautionarily provided to sustain aquatic ecosystems at the scale of large basins or countries, they explain a remarkably negligible 0%–1% of the global variability in locally derived estimates of the percentage of river flow that must be protected at a given site. Even when comparing assessments for individual countries, thus controlling for differences in local assessment methods among jurisdictions, global e-flows estimates only marginally compared (R2 ⩽ 0.31) to local estimates. Such a disconnect between global and local assessments of e-flows requirements limits the credibility of global estimates and associated targets for water use. To accelerate the global implementation of e-flows requires further concerted effort to compile and draw from the thousands of existing local e-flows assessments worldwide for developing a new generation of global models and bridging the gap from local to global scales..
The data repository includes data required to perform this analysis as well as the data outputs from this analysis. Input data from local e-flow assessments included herein were either provided by collaborators or extracted from published governmental and academic reports by the authors. Input hydrographic data not available for download elsewhere were provided by Dr. Bernhard Lehner and hydrological simulations from PCR-GLOBWB 2.0 at a spatial resolution of 5 arc-min (not provided herein) were provided by Dr. ir. Edwin H. Sutanudjaja.
All scripts necessary to reproduce this analysis are freely available for all purposes (and can be copied, modified and distributed) at: https://github.com/messamat/globalEF_testPy (for data-preformatting and global e-flow calculations) and https://github.com/messamat/globalEF_testR (for comparing global and local MAF and e-flow estimates). The structure of the analysis relies as much as possible on good enough practices in scientific computing, which users are encouraged to read.
2. Repository content ----------------------------------------------------------
The data repository has the following structure, which must be conserved to run the analysis workflow:
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data/
Formatted_data_Chandima_20211018: pre-formatted local e-flow assessment sites.
Formatted_data_Chandima_20211102: pre-formatted local e-flow assessment sites.
GEFIS_test_data/:
Master Data Table_20230424.xlsx: final database of local e-flow assessments.
HydroATLAS/: hydrographic data required for downscaling and mapping global MAF and e-flow estimates
HydroATLAS_metadata_MLMv11.xlsx: metadata of RiverATLAS attributes used in producing distribution histogram in Supplementary Material.
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results/
france_preprocessing.gdb: outputs from spatial formatting of local e-flow assessment data for the Rhone River basin in France. The main output file is /Rhone_EFpoints_cleanjoin.
mexico_preprocessing.gdb: outputs from spatial formatting of local e-flow assessment data for Mexico. The main output file is /Mexico_EFpoints_cleanjoin.
processing_outputs.gdb: outputs from overall spatial formatting of local e-flow assessment data. The fully formatted point data of the sites is: EFpoints_20230424_clean_riverjoin. Associated with global e-flow estimates: EFpoints_20230424_clean_globalEF.
victoria_preprocessing.gdb: outputs from spatial formatting of local e-flow assessment data for the state of Victoria, Australia. The main output file is /Victoria_EFpoints_cleanjoin.
EFpoints_20230424_clean_globalEF.csv: all global e-flow estimates extracted for local e-flow assessment sites.
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isimp2_qtot_accumulated15s.gdb.zip: all global MAF and e-flow estimates in raster format. In the analytical workflow, these data are in the results/ folder but here they have been placed outside to conform with the maximum file size limit of this dataverse.
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README_Technical_documentation_globalEFcomparison_Messageretal2023.pdf : documentation for this repository
3. Data format and projection ----------------------------------------------------------
The spatial datasets are distributed in ESRI® file geodatabase format. Please contact the author should you want the data in another format. These datasets are available in compressed zip file format. To use the data files, the zip files must first be decompressed.
All data layers are provided in geographic (latitude/longitude) projection, referenced to datum WGS84. In ESRI® software this projection is defined by the geographic coordinate system GCS_WGS_1984 and datum D_WGS_1984 (EPSG: 4326).
4. License and citations ----------------------------------------------------------
4.1 License agreement
This documentation and datasets are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (CC-BY-4.0 License). For all regulations regarding license grants, copyright, redistribution restrictions, required attributions, disclaimer of warranty, indemnification, liability, waiver of damages, and a precise definition of licensed materials, please refer to the License Agreement (https://creativecommons.org/licenses/by/4.0/legalcode). For a human-readable summary of the license, please see https://creativecommons.org/licenses/by/4.0/.
4.2 Citations and acknowledgements.
Citations and acknowledgements of this dataset should be made as follows:
Messager, M. L., Dickens, W. S. C., Eriyagama, N., Tharme, R. E., Stassen, R. (2024). Limited comparability of global and local estimates of
environmental flow requirements to sustain river ecosystems. Environmental Research Letters. https://doi.org/10.1088/1748-9326/ad1cb5.
We kindly ask users to cite this study in any published material produced using it. If possible, online links to this repository (DOI) should also be provided
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