Using the right slope of the 970nm absorption feature for estimating canopy water content

Canopy water content (CWC) is important for understanding the functioning of terrestrial ecosystems. Biogeochemical processes like photosynthesis, transpiration and net primary production are related to foliar water. The first derivative of the reflectance spectrum at wavelengths corresponding to the left slope of the minor water absorption band at 970 nm was found to be highly correlated with CWC and PROSAIL model simulations showed that it was insensitive to differences in leaf and canopy structure, soil background and illumination and observation geometry. However, these wavelengths are also located close to the water vapour absorption band at about 940 nm. In order to avoid interference with absorption by atmospheric water vapour, the potential of estimating CWC using the first derivative at the right slope of the 970 nm absorption feature was studied. Measurements obtained with an ASD FieldSpec spectrometer for three test sites were related to CWC (calculated as the difference between fresh and dry weight). The first site was a homogeneous grassland parcel with a grass/clover mixture. The second site was a heterogeneous floodplain with natural vegetation like grasses and various shrubs. The third site was an extensively grazed fen meadow. Results for all three test sites showed that the first derivative of the reflectance spectrum at the right slope of the 970 nm absorption feature was linearly correlated with CWC. Correlations were a bit lower than those at the left slope (at 942.5 nm) as shown in previous studies, but better than those obtained with water band indices. FieldSpec measurements showed that one may use any derivative around the middle of the right slope within the interval between 1015 nm and 1050 nm. We calculated the average derivative at this interval. The first site with grassland yielded an R2 of 0.39 for the derivative at the previously mentioned interval with CWC (based on 20 samples). The second site at the heterogeneous floodplain yielded an R2 of 0.45 for this derivative with CWC (based on 14 samples). Finally, the third site with the fen meadow yielded an R2 of 0.68 for this derivative with CWC (based on 40 samples). Regression lines between the derivative at the right slope of the 970 nm absorption feature and CWC for all three test sites were similar although vegetation types were quite different. This indicates that results may be transferable to other vegetation types and other sites

Recellularization of Porcine Internal Thoracic Arteries as a Tissue Engineered Small-Diameter Vascular Graft Alternative

Small-diameter vascular grafts are the leading treatment for myocardial infarctions resulting from atherosclerosed coronary vasculature. A potential alternative to using patient-derived grafts is the use of tissue engineered vessels. The removal of native cells from xenogenic vessels allows for recellularization with human cells types; however, the decellularization process depends on the use of cytotoxic reagents that must be removed prior to recellularization. The recellularization process must produce a functional graft that contains the multiple cell types found within arteries. We hypothesized that porcine internal thoracic arteries decellularized using a combination of detergents could be processed to support human endothelial and smooth muscle cell growth. We also hypothesized that in order to optimize in vitro co-culture conditions during recellularization, a mix of media types would be necessary to simultaneously support endothelial and smooth muscle cell growth. A cytotoxicity assay was performed to assess the effects of residual detergents on endothelial cells seeded onto the scaffolds. A relationship between the degree of detergent rinsing and cellular viability was identified via a resazurin reduction assay with more extensive rinsing significantly enhancing cell viability. This same cell viability assay was used to identify media combinations that supported growth of both endothelial and smooth muscle cells. Both cell types were able to grow in a 50:50 mixture of their media types without any loss of viability or effect on morphology. Furthermore, endothelial cells grown in the mixed medium maintained their characteristic CD31 expression. Taken together, these results show that human cells native to arteries can remain viable within the extracellular matrix of porcine internal thoracic artery scaffolds after thorough scaffold detoxification. Additionally, the co-culture conditions established can support the growth of both endothelial and smooth muscle cell types found within arteries. Future work will focus on simultaneously culturing the cells within scaffolds to build toward the goal of tissue engineering small-diameter vascular graft alternatives.https://digitalcommons.winthrop.edu/sureposters/1005/thumbnail.jp

What are the prospects for citizen science in agriculture? Evidence from three continents on motivation and mobile telephone use of resource-poor farmers

As the sustainability of agricultural citizen science projects depends on volunteer farmers who contribute their time, energy and skills, understanding their motivation is important to attract and retain participants in citizen science projects. The objectives of this study were to assess 1) farmers’ motivations to participate as citizen scientists and 2) farmers’ mobile telephone usage. Building on motivational factors identified from previous citizen science studies, a questionnaire based methodology was developed which allowed the analysis of motivational factors and their relation to farmers’ characteristics. The questionnaire was applied in three communities of farmers, in countries from different continents, participating as citizen scientists. We used statistical tests to compare motivational factors within and among the three countries. In addition, the relations between motivational factors and farmers characteristics were assessed. Lastly, Principal Component Analysis (PCA) was used to group farmers based on their motivations. Although there was an overlap between the types of motivations, for Indian farmers a collectivistic type of motivation (i.e., contribute to scientific research) was more important than egoistic and altruistic motivations. For Ethiopian and Honduran farmers an egoistic intrinsic type of motivation (i.e., interest in sharing information) was most important. While fun has appeared to be an important egoistic intrinsic factor to participate in other citizen science projects, the smallholder farmers involved in this research valued ‘passing free time’ the lowest. Two major groups of farmers were distinguished: one motivated by sharing information (egoistic intrinsic), helping (altruism) and contribute to scientific research (collectivistic) and one motivated by egoistic extrinsic factors (expectation, expert interaction and community interaction). Country and education level were the two most important farmers’ characteristics that explain around 20% of the variation in farmers motivations. For educated farmers, contributing to scientific research was a more important motivation to participate as citizen scientists compared to less educated farmers. We conclude that motivations to participate in citizen science are different for smallholders in agriculture compared to other sectors. Citizen science does have high potential, but easy to use mechanisms are needed. Moreover, gamification may increase the egoistic intrinsic motivation of farmers

Fean wetter buorkje II : Samenvattende rapportage praktijkproeven hoger zomerpeil Fries Veenweidegebied 2007-2008

De provincie Fryslân en Wetterskip Fryslân zoeken naar een vorm van peilbeheer die de bodemdaling in het Friese veenweidegebied vertraagt, maar een sterke landbouw niet in de weg staat. De oplossing wordt gezocht in hoger zomerpeil. Daarbij is ’s zomers, wanneer vanwege de lagere grondwaterstanden en de hogere temperaturen 90% van de bodemdaling plaatsvindt, de drooglegging 60-70 cm, terwijl die ‘s winters 90 cm blijft