8 results on '"Roosjen, Peter, P.J."'
Search Results
2. Deep learning for automated detection of Drosophila suzukii : potential for UAV-based monitoring
- Author
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Roosjen, Peter P.J., Kellenberger, Benjamin, Kooistra, Lammert, Green, David R., Fahrentrapp, Johannes, Roosjen, Peter P.J., Kellenberger, Benjamin, Kooistra, Lammert, Green, David R., and Fahrentrapp, Johannes
- Abstract
BACKGROUND: The fruit fly Drosophila suzukii, or spotted wing drosophila (SWD), is a serious pest worldwide, attacking many soft-skinned fruits. An efficient monitoring system that identifies and counts SWD in crops and their surroundings is therefore essential for integrated pest management (IPM) strategies. Existing methods, such as catching flies in liquid bait traps and counting them manually, are costly, time-consuming and labour-intensive. To overcome these limitations, we studied insect trap monitoring using image-based object detection with deep learning. RESULTS: Based on an image database with 4753 annotated SWD flies, we trained a ResNet-18-based deep convolutional neural network to detect and count SWD, including sex prediction and discrimination. The results show that SWD can be detected with an area under the precision recall curve (AUC) of 0.506 (female) and 0.603 (male) in digital images taken from a static position. For images collected using an unmanned aerial vehicle (UAV), the algorithm detected SWD individuals with an AUC of 0.086 (female) and 0.284 (male). The lower AUC for the aerial imagery was due to lower image quality caused by stabilisation manoeuvres of the UAV during image collection. CONCLUSION: Our results indicate that it is possible to monitor SWD using deep learning and object detection. Moreover, the results demonstrate the potential of UAVs to monitor insect traps, which could be valuable in the development of autonomous insect monitoring systems and IPM.
- Published
- 2020
3. High-Throughput Screening Model to Quantify Re-Epithelialization Kinetics
- Author
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Fernandez-Gutierrez, Marcela M., Roosjen, Peter P.J., van Zessen, David B.H., Wells, Jerry M., van Baarlen, Peter, Stubbs, Andrew P., Kleerebezem, Michiel, Fernandez-Gutierrez, Marcela M., Roosjen, Peter P.J., van Zessen, David B.H., Wells, Jerry M., van Baarlen, Peter, Stubbs, Andrew P., and Kleerebezem, Michiel
- Abstract
In vitro scratch assays provide an attractive method to study the regulation and mechanisms of epithelial cell proliferation and migration that are involved in wound repair. The assay is performed by introducing a scratch into a confluent cell monolayer and monitoring the re-epithelialization of the “wound” by acquiring images over time. Despite improvements to the method over the past years, high-throughput screenings often require the integration of multiple image analysis and data extraction software tools. We developed a high-throughput image-based scratch assay and an automated processing pipeline that employs a mathematical model to describe re-epithelialization kinetics. We implemented a processing pipeline in Galaxy called KREAP that provides an open source web-based platform to enable scientists from diverse backgrounds to perform reproducible and quantitative repair data analyses in less than 45 minutes.
- Published
- 2019
4. Improved estimation of leaf area index and leaf chlorophyll content of a potato crop using multi-angle spectral data - potential of unmanned aerial vehicle imagery
- Author
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Roosjen, Peter, P.J., Brede, Benjamin, Suomalainen, Juha, M., Bartholomeus, Harm, M., Kooistra, Lammert, Clevers, Jan, G.P.W., National Land Survey of Finland, and Maanmittauslaitos
- Subjects
multi-angular reflectance ,reflectance anisotropy ,leaf area index ,PROSAIL ,unmanned aerial vehicle ,Leaf chlorophyll content ,model inversion - Abstract
In addition to single-angle reflectance data, multi-angular observations can be used as an additional information source for the retrieval of properties of an observed target surface. In this paper, we studied the potential of multi-angular reflectance data for the improvement of leaf area index (LAI) and leaf chlorophyll content (LCC) estimation by numerical inversion of the PROSAIL model. The potential for improvement of LAI and LCC was evaluated for both measured data and simulated data. The measured data was collected on 19 July 2016 by a frame-camera mounted on an unmanned aerial vehicle (UAV) over a potato field, where eight experimental plots of 30 × 30 m were designed with different fertilization levels. Dozens of viewing angles, covering the hemisphere up to around 30° from nadir, were obtained by a large forward and sideways overlap of collected images. Simultaneously to the UAV flight, in situ measurements of LAI and LCC were performed. Inversion of the PROSAIL model was done based on nadir data and based on multi-angular data collected by the UAV. Inversion based on the multi-angular data performed slightly better than inversion based on nadir data, indicated by the decrease in RMSE from 0.70 to 0.65 m2/m2 for the estimation of LAI, and from 17.35 to 17.29 μg/cm2 for the estimation of LCC, when nadir data were used and when multi-angular data were used, respectively. In addition to inversions based on measured data, we simulated several datasets at different multi-angular configurations and compared the accuracy of the inversions of these datasets with the inversion based on data simulated at nadir position. In general, the results based on simulated (synthetic) data indicated that when more viewing angles, more well distributed viewing angles, and viewing angles up to larger zenith angles were available for inversion, the most accurate estimations were obtained. Interestingly, when using spectra simulated at multi-angular sampling configurations as were captured by the UAV platform (view zenith angles up to 30°), already a huge improvement could be obtained when compared to solely using spectra simulated at nadir position. The results of this study show that the estimation of LAI and LCC by numerical inversion of the PROSAIL model can be improved when multi-angular observations are introduced. However, for the potato crop, PROSAIL inversion for measured data only showed moderate accuracy and slight improvements.
- Published
- 2018
5. UAV-based multi-angular measurements for improved crop parameter retrieval
- Author
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Roosjen, Peter P.J., Wageningen University, M. Herold, J.G.P.W. Clevers, and H.M. Bartholomeus
- Subjects
remote sensing ,drones ,Laboratory of Geo-information Science and Remote Sensing ,reflectance ,bodemwatergehalte ,gewassen ,Laboratorium voor Geo-informatiekunde en Remote Sensing ,soil water content ,anisotropy ,reflectiefactor ,PE&RC ,crops ,anisotropie - Abstract
Optical remote sensing enables the estimation of crop parameters based on reflected light through empirical-statistical methods or inversion of radiative transfer models. Natural surfaces, however, reflect light anisotropically, which means that the intensity of reflected light depends on the viewing and illumination geometry. Therefore, reflectance anisotropy can be considered as an unwanted effect since it may lead to inaccuracies in parameter estimations. However, it can also be considered as information source due to its unique response to the optical and structural properties of the observed surface. In the past, reflectance anisotropy was studied by multi-angular reflectance measurements from space-borne or ground-based sensors. In this research, the opportunities of Unmanned Aerial Vehicles (UAVs) to collect multi-angular measurements were explored. The main results of this research show that multi-angular measurements can be done with UAVs and that the reflectance anisotropy signal can be used to improve the retrieval of crop parameters.
- Published
- 2017
6. UAV-based multi-angular measurements for improved crop parameter retrieval
- Author
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Herold, M., Clevers, J.G.P.W., Bartholomeus, H.M., Roosjen, Peter P.J., Herold, M., Clevers, J.G.P.W., Bartholomeus, H.M., and Roosjen, Peter P.J.
- Abstract
Optical remote sensing enables the estimation of crop parameters based on reflected light through empirical-statistical methods or inversion of radiative transfer models. Natural surfaces, however, reflect light anisotropically, which means that the intensity of reflected light depends on the viewing and illumination geometry. Therefore, reflectance anisotropy can be considered as an unwanted effect since it may lead to inaccuracies in parameter estimations. However, it can also be considered as information source due to its unique response to the optical and structural properties of the observed surface. In the past, reflectance anisotropy was studied by multi-angular reflectance measurements from space-borne or ground-based sensors. In this research, the opportunities of Unmanned Aerial Vehicles (UAVs) to collect multi-angular measurements were explored. The main results of this research show that multi-angular measurements can be done with UAVs and that the reflectance anisotropy signal can be used to improve the retrieval of crop parameters.
- Published
- 2017
7. Streptococcus salivarius MS-oral-D6 promotes gingival re-epithelialization in vitro through a secreted serine protease
- Author
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Fernandez Gutierrez, Maria, Roosjen, Peter P.J., Ultee, Eveline, Agelink, Maarten, Vervoort, Jacques J.M., Keijser, Bart, Wells, Jerry M., Kleerebezem, Michiel, Fernandez Gutierrez, Maria, Roosjen, Peter P.J., Ultee, Eveline, Agelink, Maarten, Vervoort, Jacques J.M., Keijser, Bart, Wells, Jerry M., and Kleerebezem, Michiel
- Abstract
Gingival re-epithelialization represents an essential phase of oral wound healing in which epithelial integrity is re-establish. We developed an automated high-throughput re-epithelialization kinetic model, using the gingival epithelial cell line Ca9-22. The model was employed to screen 39 lactic acid bacteria, predominantly including oral isolates, for their capacity to accelerate gingival re-epithelialization. This screen identified several strains of Streptococcus salivarius that stimulated re-epithelialization. Further analysis revealed that S. salivarius strain MS-oral-D6 significantly promoted re-epithelialization through a secreted proteinaceous compound and subsequent experiments identified a secreted serine protease as the most likely candidate to be involved in re-epithelialization stimulation. The identification of bacteria or their products that stimulate gingival wound repair may inspire novel strategies for the maintenance of oral health.
- Published
- 2017
8. UAV-based multi-angular measurements for improved crop parameter retrieval
- Author
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Roosjen, Peter P.J., primary
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