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Validating the probabilistic sex diagnosis (DSP) method with a special test case on Pre-Columbian mummies (including the famous Rascar Capac)
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Many museums have either one or more mummies in their collections. The Royal Museums of Art and History in Brussels is no exception and houses several Pre-Columbian mummies, including the one that inspired Hergé, author of the Tintin comics, to create the character of ‘Rascar Capac’. The accurate identification of the sex of a particular mummy is important for testing hypotheses about social structures in ancient societies. Sexing of mummies is mostly based on visual analysis from CT and MRI scans and macroscopic examination from the skeletal tissue such as genitalia and breasts, although skeletal tissue is not always well preserved. Probabilistic Sex Diagnosis (DSP: Diagnose Sexuelle Probabiliste) is a sex estimation method which has recently proved to be highly effective on different modern human and ancient European populations. The aim of this study was to see if it was possible to apply and validate virtual DSP on a study of four ancient Pre-Columbian mummies from South America (which are outside the reference population of DSP). Virtual DSP was performed in the software ‘lhpFusionBox’. All mummies were CT scanned, 3D models were created and virtual DSP was performed. Sex was determined with a probability of 99.9% or over in all cases (DSP determined one male and three females). Preserved skeletal tissue remains confirmed DSP results in half of the mummies. A Principal Components Analysis (PCA) was performed on the DSP results of the mummies and a modern human (MH) population. Half of the mummies were outside the 95% range of the DSP values of MH, largely due to their smaller size. When size was accounted for, they were within the MH range. The unknown sex mummies identified as females by DSP were found to be grouped with the known sex female mummy and the MH females. Similarly, the unknown sex mummy identified as male by DSP was also found to be grouped with MH males. The use of PCA analysis on DSP results is an effective tool to validate DSP results, even with individuals outside of the reference population. Despite differences in size from ancient to modern humans, DSP was found to be accurate and can be used with mummies and other ancient populations from different countries around the world.
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RBINS Staff Publications 2020
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Validation of Landsat 8 high resolution Sea Surface Temperature using surfers
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Nearshore coastal waters are highly dynamic in both space and time. They can be difficult to sample using conventional methods due to their shallow depth, tidal variability, and the presence of strong currents and breaking waves. High resolution satellite sensors can be used to provide synoptic views of Surface Temperature (ST), but the performance of such ST products in the nearshore zone is poorly understood. Close to the shoreline, the ST pixels can be influenced by mixed composition of water and land, as a result of the sensor’s spatial resolution. This can cause thermal adjacency effects due to the highly different diurnal temperature cycles of water bodies and land. Previously, temperature data collected during surfing sessions has been proposed for validation of moderate resolution (1 km pixel size) satellite ST products. In this paper we use surfing temperature data to validate three high resolution (100 m resampled to 30 m pixel size) ST products derived from the Thermal InfraRed Sensor (TIRS) on board Landsat 8 (L8). ST was derived from Collection 1 and 2 Level 1 data (C1L1 and C2L1) using the Thermal Atmospheric Correction Tool (TACT), and was obtained from the standard Collection 2 Level 2 product (USGS C2L2). This study represents one of the first evaluations of the new C2 products, both L1 and L2, released by USGS at the end of 2020. Using automated matchup and image quality control, 88 matchups between L8/TIRS and surfers were identified, distributed across the North-Western semihemisphere. The unbiased Root Mean Squared Difference (uRMSD) between satellite and in situ measurements was generally ¡ 2 K, with warm biases (Mean Average Difference, MAD) of 1.7 K (USGS C2L2), 1.3 K (TACT C1L1) and 0.8 K (TACT C2L1). Large interquartile ranges of ST in 5 × 5 satellite pixels around the matchup location were found for several images, especially for the summer matchups around the Californian coast. By filtering on target stability the number of matchups reduced to 31, which halved the uRMSD across the three methods (to around 1.1K), MAD were much lower, i.e. 1.1 K (USGS C2L2), 0.6 K (TACT C1L1), and 0.2 K (TACT C2L1). The larger biases of the C2L2 product compared to TACT C2L1 are caused as a result of: (1) a lower emissivity value for water targets used in USGS C2L2, and (2) differences in atmospheric parameter retrieval, mainly from differences in upwelling atmospheric radiance and lower atmospheric transmittance retrieved by USGS C2L2. Additionally, tiling artefacts are present in the C2L2 product, which originate from a coarser atmospheric correction process. Overall, the L8/TIRS derived ST product compares well with in situ measurements made while surfing, and we found the best performing ST product for nearshore coastal waters to be the Collection 2 Level 1 data processed with TACT.
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RBINS Staff Publications 2022
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Validation of the 3D biogeochemical model MIRO&CO with field nutrient and phytoplankton data and MERIS-derived surface chlorophyll a images.
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This paper presents results obtained with MIRO&CO-3D, a biogeochemical model dedicated to the study of eutrophication and applied to the Channel and Southern Bight of the North Sea (48.5°N–52.5°N). The model results from coupling of the COHERENS-3D hydrodynamic model and the biogeochemical model MIRO, which was previously calibrated in a multi-box implementation. MIRO&CO-3D is run to simulate the annual cycle of inorganic and organic carbon and nutrients (nitrogen, phosphorus and silica), phytoplankton (diatoms, nanoflagellates and Phaeocystis), bacteria and zooplankton (microzooplankton and copepods) with realistic forcing (meteorological conditions and river loads) for the period 1991–2003. Model validation is first shown by comparing time series of model concentrations of nutrients, chlorophyll a, diatom and Phaeocystis with in situ data from station 330 (51°26.00′N, 2°48.50′E) located in the centre of the Belgian coastal zone. This comparison shows the model's ability to represent the seasonal dynamics of nutrients and phytoplankton in Belgian waters. However the model fails to simulate correctly the dissolved silica cycle, especially during the beginning of spring, due to the late onset (in the model) of the early spring diatom bloom. As a general trend the chlorophyll a spring maximum is underestimated in simulations. A comparison between the seasonal average of surface winter nutrients and spring chlorophyll a concentrations simulated with in situ data for different stations is used to assess the accuracy of the simulated spatial distribution. At a seasonal scale, the spatial distribution of surface winter nutrients is in general well reproduced by the model with nevertheless a small overestimation for a few stations close to the Rhine/Meuse mouth and a tendency to underestimation in the coastal zone from Belgium to France. PO4 was simulated best; silica was simulated with less success. Spring chlorophyll a concentration is in general underestimated by the model. The accuracy of the simulated phytoplankton spatial distribution is further evaluated by comparing simulated surface chlorophyll a with that derived from the satellite sensor MERIS for the year 2003. Reasonable agreement is found between simulated and satellite-derived regions of high chlorophyll a with nevertheless discrepancies close to the boundaries.
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RBINS Staff Publications
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Validité du genre Olentangiella CASIER, 1985 (Ostracoda, Dévonien): réponse à la note de G. BECKER (1990).
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RBINS Staff Publications
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Valve chemistry of Limnocythere inopinata (Ostracoda) in a cold arid environment - implications for paleolimnological interpretation
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RBINS Staff Publications
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Valve shape is not linked to genetic species in the Eucypris virens (Ostracoda, Crustacea) species complex
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RBINS Staff Publications 2016
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Variability in ostracod communities (Crustacea, Ostracoda) in connected and isolated tropical floodplain lakes
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Floodplains mostly consist of primary and secondary riverbeds, connecting channels and lakes that are either isolated from rivers and channels for most of the year, or lakes that are connected to rivers and channels for most (or all) of the year. We hypothesize that the differences in invertebrate communities, as calculated by beta-diversities, will be higher in isolated than in connected lakes. We use ostracod communities in the pleuston of the floating macrophyte Eichhornia crassipes in the Upper Paraná River floodplain to test this hypothesis. We have observed significant differences in species composition between the two types of lakes. However, although beta diversity values are indeed slightly higher in isolated than in connected lakes, these differences are not significant. This lack of clear effect of isolation on beta diversity could be owing to the fact that the period of isolation since the last homogenizing flood pulse had not been long enough, or because differences in degree of isolation become altogether insignificant in periods of low water flow.
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RBINS Staff Publications 2017
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Variability in radiocarbon dates in Middle Pleniglacial wood from Kurtak (Central Siberia)
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RBINS Staff Publications
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Variability of pterygoid teeth in three species of Podarcis lizards and the utility of palatal dentition in lizard systematics
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Belgian Journal of Zoology
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Bibliographic References
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Variability of Suspended Particulate Matter in the Bohai Sea from the Geostationary Ocean Color Imager (GOCI)
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This study assesses the performance of the Geostationary Ocean Imager (GOCI) for mapping of suspended particulate matter in the Bohai Sea, a turbid water region. GOCI imagery for remote sensing reflectance and Total Suspended Solids (TSS) is analysed in detail for two days in June 2011 (8 images per day). Both instantaneous and daily composite maps are considered and a comparison is made with corresponding reflectance and TSS products from MODIS-AQUA. Results show TSS distributions corresponding to previous studies of the region. The advantage of the higher acquisition frequency (8 images/day instead of 1) offered by GOCI is clearly demonstrated in the daily composite which is more complete during this period of scattered but moving clouds. Consideration of temporal variation over the day indicates low natural variability but some artificial variability from processing errors - this analysis provides a first indication of how the higher frequency of data from geostationary ocean colour could lead to improved data quality control via temporal coherency outlier detection. While there is room for improvement on the GOCI calibration, atmospheric correction and retrieval algorithms, the current study suggests that the GOCI data can already be used now to study qualitatively sediment dynamics except in the extremely turbid waters which are masked out of the current dataset. In a wider context, it is considered that the technical challenges of geostationary ocean colour have been met by the GOCI concept, and, notwithstanding potential improvements on the concept and data processing methods, it is recommended that this mission serve as a model for future geostationary ocean colour sensors over Europe/Africa and the Americas.
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