62 research outputs found
The Future Is in the Younger Generations: Baka Children in Southeast Cameroon Have Extensive Knowledge on Medicinal Plants
No full textAltres ajuts: acords transformatius de la UABUnidad de excelencia María de Maeztu CEX2019-000940-MIn the context of global change, understanding the knowledge and values given to plants is crucial for choosing relevant approaches towards a more sustainable future. Children are central holders of ethnobotanical knowledge, yet they are still under-considered in ethnobotany. Our study explored the medicinal knowledge of children of the Baka, forager-horticulturalists from Cameroon. We assessed the diversity of medicinal plants they know, the different ailments treated, and whether they could name complete herbal recipes. Using a mixed-methods approach, we combined ex situ interviews (freelisting and knowledge surveys) with in situ methods (walk-in-the-woods trips with voucher collection) with 106 children from 5 to 16 years old. They listed 128 local names of medicinal plants, which we linked to 126 different plant species. While the ex situ and in situ methods had some overlap in the diversity of medicinal plants reported, they also revealed substantial knowledge unique to each method. Our insights provide further evidence of children's considerable ethnobotanical knowledge and the extent to which different field methods can retrieve such knowledge. We discuss the methodological tools to be developed with and for children to put childhood at the center stage of ethnobotanical approaches for the future
Validation of the Composite Propeller Application and flexible propeller design space exploration
No full textPropellers are used to propel the vast majority of ships. They are most commonly made out of Nickel-Aluminum-Bronze alloys. This is due to their superior characteristics over other metals in terms of strength and corrosion resistance. Metal propellers are assumed to be rigid and undeformable. Current research opts to construct propellers out of more flexible materials such as composites. The potential of this material lies in the theory that this results in propellers which could unload themselves in the wake peak, which should lead to significant improvements in the cavitation- and noise behaviour of the propeller.Since the material is much less stiff, the deformation can no longer be neglected and must be computed simultaneously with the hydrodynamic solution. This is done in a branch of fluid dynamics known as Fluid-Structure Interaction (FSI). Maritime Research Institute Netherlands (MARIN) is involved in the development of a program known as the ComPropApp.The first goal of this thesis is to validate the unsteady FSI module of the ComPropApp which uses a coupled BEM-FEM code to calculate the hydrodynamic and structural performance of marine propellers in non-uniform inflow conditions. The numerical simulations are validated by comparison with conducted experiments at MARIN. It shows that the average deformation of the experiment and simulation are in good agreement but the ComPropApp overestimates the wake peak deformation. This is most likely the effect of divergence issues which do not allow for sufficiently small step sizes. This step size also does not allow for analysis of vibrations happening within a revolution as much more points should be considered. The most important recommendation, therefore, is to improve the numerical stability of the application.The second goal is the exploration of the design space of flexible propellers. By altering propeller geometry parameters it is investigated which parameters have the potential to design adequate flexible propellers in the future. To quickly assess the cavitation risk of the propellers, the amount of negative pressure coefficients on the blade is used to quantify the cavitation risk in the initial propeller design stage. Through this method, it is shown that suction side cavitation risk is decreased easily by altering pitch, skew, chord length and camber. Pressure side cavitation risk is however much harder to relieve, mostly because of the deformation of flexible propellers. Yet, cavitation risk can be decreased with a combination of skew and camber. It is also shown that unfavourable tip pressures (thus risk of tip vortices) can be further decreased by applying a positive tip rake.All these propellers were simulated in open water (because of the above-mentioned divergence issues in the unsteady FSI module). Thus it is no conclusion that these propellers also perform adequately in non-uniform inflow conditions. It is shown with a demonstration that two of the three most potential propellers of the open water study do indeed unload themselves and maintain better cavitation behaviour at the velocity in the wake peak compared to a metal reference propeller.Marine Technolog
Supplement to the Faunal List of the Birds of the Moluccan Islands
No full textA faunal list of the birds of the Moluccan Islands has been previously published by the first author (Treubia 19, part 2, May 1948, pp. 323— 402). Additional data have been collected since by Mr. G. A. L. de Haan during a period of several years in which this zealous collector lived in Halmahera and visited the islands Morotai, Ternate and Gebe. It seemed us worth while to publish the species and new localities from the data collected by Mr de Haan, which are not contained in the previous list. We take this opportunity to add some data from literature, published after May 1948 or overlooked by the first author, some data from the collections of the American Museum of Natural History, New York, and the Rijksmuseum van Natuurlijke Historie. Leiden, and to add some corrections to the first list.
We want to express our sincere thanks to Mr de Haan for all troubles taken to provide us with material and information, to Dr E. Mayr (New York) for his corrections and valuable information, to Dr M. A. Lieftinck (Bogor) and Prof. Dr H. Boschma (Leiden) and Dr G. C. A. Junge (Leiden) for material put at our disposal
Evaluation of three newly developed enzyme-linked immunosorbent assays and two agglutination tests for detecting Salmonella enterica subsp. enterica serovar dublin infections in dairy cattle
No full textIn this study test characteristics of three newly developed enzyme-linked immunosorbent assays (ELISAs) for Salmonella enterica subsp. enterica serovar Dublin were evaluated and compared with two agglutination tests. The ELISAs involved were an indirect ELISA with serovar Dublin lipopolysaccharide (LPS ELISA), an indirect ELISA with serovar Dublin flagellar antigen (GP ELISA), and a double-antibody sandwich blocking ELISA that uses monoclonal antibodies against S. enterica subsp. enterica serovar Enteritidis flagellin (GM-DAS ELISA). The agglutination tests involved were two routine serum agglutination tests with either somatic (O) or flagellar (H) antigen. Diagnostic specificity of the three ELISAs was determined using 840 serum samples from seven dairy herds without any history of serovar Dublin infection. Cutoff values at a titer of 100, 100, and 10, respectively, for the LPS ELISA, GP ELISA, and GM-DAS blocking ELISA resulted in a specificity of 99.3, 100, and 100%, respectively. Using these cutoff values the LPS ELISA, GP ELISA, and GM-DAS ELISA were able to detect, respectively, 30, 46, and 38% of 50 fecal culture-positive animals from 13 herds with a recent serovar Dublin infection. With the same cutoff values, active carriers (n = 18) were detected for 94.4% with the LPS ELISA and for 100% with the GP and GM-DAS ELISAs. Kappa values determined on the results of all tests from 8 of the 13 serovar Dublin-infected herds and the 7 control herds demonstrated a good correlation between the results of all ELISAs and the H-agglutination test. The results of the O-agglutination test failed to correlate with those of the other tests. Using a set of sera from 170 aborting cows (with 25 abortions due to serovar Dublin), test results of the ELISAs and the H-agglutination test were comparable. The H-agglutination test may be used successfully for single sample testing, especially to diagnose abortion due to serovar Dublin. It is concluded that the ELISAs are useful diagnostic tools in serovar Dublin control programs and that they are preferred to agglutination tests for reasons of automation and costs.LR: 20061115; PUBM: Print; JID: 7505564; ppublishSource type: Electronic(1
On the meaning of movable attachment of the incisiviform teeth in Ruminantia
No full textIn Ruminantia, the roots of the incisiviform teeth in the lower jaw are only partially enclosed in the bony alveolus. Only the lingual part of the alveolus continues in oral direction, the labial part being open at the anterior side, and occupied by fibrous tissue, which is elastic and compact. One look at the skull of a cow, sheep, goat or deer will suffice to convince anybody of the correctness of this statement. Closing its mouth, the animal will press downwards the incisiviform teeth in the lower jaw with the gum pad of the upper jaw, till the lingual side of the crown of the front teeth meets the gum pad.
Curiously enough, this mobility of the incisiviform teeth in Ruminantia has never been explained in any handbook on dental anatomy and, in some works only, has been mentioned by the way. AITCHISON was the first author who stressed this point (P.Z.S. 116, p. 329—338, 1946)
Designing for teacher education:Exploring the concept of a responsive curriculum
No full textCurriculum designers in teacher education are challenged to design curricula that react to, and anticipate, complexity and change and make a curriculum more adaptive, flexible or responsive. The aim of the current study is to enhance understanding of the responsiveness of teacher education curricula. A curriculum is a plan for learning and it organizes, sequences and stimulates learning experiences in school and in practice (Billett, 2011). We consider a curriculum as responsive when it takes individual differences and needs of learners into account, is adaptive to a variety of contexts in occupational practice and anticipates change in society (Author, 1995; Turkenburg & Vogels, 2017). A curriculum includes different levels (micro, meso), design dimensions (epistemic, social, instrumental, temporal and spatial) and actors (students and their supervisors) (Author, 2019; Van den Akker, 2013). In this participative design research a variety of design initiatives in five bachelor science teacher education programs (ISCED 6) are included. Data sources were documents, participatory observations of organized design sessions, project meetings, and just-in-time interviews. A logbook was used to keep track of the initiatives and to reflect on design activities including creative leaps. The data was analyzed qualitatively using templates. The results are expected before the Jure conference in August 2021.<br/
Planning a census of the Harbour Seal (Phoca vitulina L.) on the coasts of the Netherlands
No full textScientific research into the occurrence and population density of the Harbour Seal ( Phoca vitulina L.) in the coastal regions of the Netherlands, necessary for any efficacious nature conservancy programme, was started in September 1953 by the author.
A reliable calculation of the total number of Harbour Seals in the coastal regions of the Netherlands soon proved to be extremely difficult. Estimations of the number of Harbour Seals occurring in these regions had been made several times before. BROUWER (1927) took the total number of seals in the Netherlands part of the Waddenzee at 1500 and the total number of seals in the estuaries of the provinces of Zuid-Holland and Zeeland at 800. The first number had been arrived at by means of countings in the field, the latter had been computed from the number of dead animals brought in on account of a bounty system existing for more than twenty years. HAVINGA (1931, 1933) also based his most ingenious calculations on the number of animals killed for bounties. He found that, should the total number of seals stay at the same level, the total population should amount to at least 4000 animals, the bounty killings amounting to 1100 animals annually. At the moment HAVINGA published his report, there was no direct evidence of a decrease in the number of seals, but even so HAVINGA obviously felt a slight doubt in this respect. ERNA MOJHR (1952) compared HAVINGA’S calculations with Russian calculations concerning the Harp Seal (Phoca groentandica FABR.). Her conclusions are that only a total number of 8500 animals was sufficient to endure an annual killing of 1100 animals without decreasing. To my opinion ERNA MOHR was mistaken in using these calculations, concerning a species with quite another biology and a shorter span of life than the Harbour Seal. So, taking into account the Harbour Seal only, the various authors came to different estimations in the coastal regions of the Netherlands. Therefore it seemed worthwhile to attempt a more exact census of this species
Groundwater and solute transport modelling study Vosdonk Noord at Etten-Leur: Examining the effect of two implementation methodologies for highly heterogenic shallow subsurface characteristics
No full textThe industrial site of Vosdonk Noord at Etten-Leur in the Netherlands consists of a large soil contamination in combination with highly heterogenic shallow subsurface soil characteristics. In this report, we study the groundwater flow and solute transport behaviour at this project location. Throughout this process, knowledge is gathered about the interpretation of the shallow subsurface heterogeneity with a main focus on the hydraulic conductivities. It is interesting to look at the subsurface heterogeneity because of the challenge to implement it inside a model and its uncertainty in characteristics. This means the subsurface heterogeneity is part of the problem to be solved. A comparison of groundwater flow and solute transport results were made using kriging as an interpolation method to implement subsurface cone penetration test data directly into the model. This generated a cell by cell implementation of the subsurface characteristics. To include the possible variability of the subsurface and to increase the reliability of the results, random simulations were implemented. In practice, the “pancake” method characterises the subsurface in a commercial software like Visual Modflow. This “pancake” method uses continuous horizontal subsurface soil layers. The gathered knowledge is useful to try and tackle the in practice used “pancake” method in case of a highly heterogenic subsurface
Port of Altamira, Mexico
No full textMaster project report. The Port of Altamira is one of the fast growing ports in the world and is together with Veracruz and Coatzacoalcos one of the biggest ports of Mexico at the Gulf coast. It is an industrial Port with a lot of potential for expanding. However, the breakwaters of the Port extending into the sea caused severe erosion at the downdrift side of the Port (south side). This ongoing erosion is threatening a precious lagoon and some important land. The erosion can also cause a breakthrough of a dune row, which will result in a flooding of the hinterland. There has to be found a solution for this ongoing erosion. The definition of the problem and the goals of this project are identified in chapter 3. An analysis has been made in chapter 4 to get insight in the environment around the port, which eventually has a big influence on the erosion. Which coastal processes are causing the initial sedimentation transport and the quantification of the erosion is described in chapter 5. To determine which solution is the best for this problem, first the wanted situation has to be estimated. This is done by looking at storm condition and the actual situation at the beach in chapter 6. This way there is made an estimation of the requirements which the alternatives have to fulfill after they are constructed. The summary of the total of requirements is given in chapter 7.Hydraulic EngineeringCivil Engineering and Geoscience
Ionospheric calibration of low frequency radio interferometric observations using the peeling scheme
No full textCalibration of radio interferometric observations becomes increasingly difficult towards lower frequencies. Below ?300 MHz, spatially variant refractions and propagation delays of radio waves traveling through the ionosphere cause phase rotations that can vary significantly with time, viewing direction and antenna location. In this article we present a description and first results of SPAM (Source Peeling and Atmospheric Modeling), a new calibration method that attempts to iteratively solve and correct for ionospheric phase errors. To model the ionosphere, we construct a time-variant, 2-dimensional phase screen at fixed height above the Earth’s surface. Spatial variations are described by a truncated set of discrete Karhunen-Loève base functions, optimized for an assumed power-law spectral density of free electrons density fluctuations, and a given configuration of calibrator sources and antenna locations. The model is constrained using antenna-based gain phases from individual self-calibrations on the available bright sources in the field-of-view. Application of SPAM on three test cases, a simulated visibility data set and two selected 74 MHz VLA data sets, yields significant improvements in image background noise (5–75 percent reduction) and source peak fluxes (up to 25 percent increase) as compared to the existing self-calibration and field-based calibration methods, which indicates a significant improvement in ionospheric phase calibration accuracy.Electrical Engineering, Mathematics and Computer Scienc
- …
