1,122 research outputs found
Digging through the dirt: a general method for abstract discrete state estimation with limited prior knowledge
No full textAutonomous robots are often successfully deployed in controlled environments. Operation in uncontrolled situations remains challenging; it is hypothesized that the detection of abstract discrete states (ADS) can improve operation in these circumstances. ADS are high-level system states that are not directly detectable and influence system dynamics. An example of a typical ADS problem that is used in this thesis is that of a wheeled robot driving through puddles of mud that, when entered, alters the velocity of the robot. When the robot is in such a puddle, it is in an ADS 'mud', and when it is not, it is in an ADS 'free'. ADS can be indirectly inferred through the analysis of lower-level data such as the velocity of the robot. The goal of this thesis is to design a general abstract discrete state estimator (ADSE) operating with limited prior knowledge. An ADSE is a hierarchical system for detecting changes in ADS. The ADSE should be general; applicable to multiple ADSE problems. The ADSE should further operate under limited prior knowledge: only assuming that the amount of ADS and the ADS that describes the regular operation are known. The basis for the ADSE designed in this thesis is a Gaussian hidden Markov model (GHMM), a hidden Markov model enhanced with Gaussian emissions. Randomly generated experiments are done on a simple but general ADSE problem. Two unsupervised learning methods derived from Expectation Maximization are evaluated, namely Baum-Welch (BW) and forward extraction (FWE). FWE is introduced in this thesis and is a simpler implementation of Viterbi extraction, leveraging assumptions of ADSE to in theory gain computational efficiency. We found that both BW and FWE exhibit superior performance compared to a likelihood-based baseline estimator when the maximum score of the learning curve is considered. When the final score is considered, in some cases, FWE displays a deteriorating learning curve, resulting in worse final scores compared to the baseline. Furthermore, it was found that the lower the overlap coefficient (therefore the less similar the ADS), the higher the maximum reached score. It was further shown that BW exhibits better convergence than FWE to the true model parameters. Besides this, FWE obtained comparable or in some cases even superior scores compared to BW. In general, from the results, the diversity of the experiments conducted, and the assumptions made we can conclude that the GHMM can be a general method for an ADSE with limited prior knowledge. To quantify the suitability of the GHMM for ADSE, further research should include the evaluation of different ADSE methods on the same problem. There exists a tradeoff between the lower computational cost FWE and the more stable but more computationally intensive BW learning. Therefore, future research can include a combination of these methods. Other extensions include extending the GHMM to a Gaussian mixture hidden Markov model to allow for the modeling of more complex distributions, or the application to multiple states or a changing environment.https://github.com/Wouter-deBoer/adseMechanical Engineering | Vehicle Engineering | Cognitive Robotic
Figs 8–14 in Review of two Tonnoir moth fly species, overlooked for a century (Diptera: Psychodidae: Psychodinae)
No full textFigs 8–14. Pneumia vittata (Tonnoir, 1919) comb. nov., male and female (13‒14). 8 – maxilla and palpus maxillaris; 9 – wing; 10 – epandrium, dorsal view; 11 – hypoproct and epiproct, dorsal view, dissected; 12 – epandrial lobe, dorsal view; 13 – cercus, lateral view; 14 – subgenital plate and genital chamber, dorsal view. Scale bars: 9 = 1 mm; 8, 10, 12, 13 = 0.2 mm; 11 = 0.1 mm; 14 = 0.3 mm.Published as part of Ježek, Jan, Oboňa, Jozef, Grootaert, Patrick, Lock, Koen, Manko, Peter & Dekoninck, Wouter, 2020, Review of two Tonnoir moth fly species, overlooked for a century (Diptera: Psychodidae: Psychodinae), pp. 517-526 in Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 60 (2) on page 520, DOI: 10.37520/aemnp.2020.034, http://zenodo.org/record/517761
Discovery of a new inland population of Amara strenua Zimmerman, 1832 at Heverlee, central Belgium (Coleoptera: Carabidae)
No full textA new inland population of the rare ground beetle Amara strenua Zimmerman, 1832 is reported for Belgium. This species was encountered during a survey using pitfall traps at Abdij van Park near Heverlee. This observation marks the first record in Flemish Brabant, as well as the most inland known population of A. strenua in Flanders. Details on the habitat and the phenology of the newly discovered population are provided. Furthermore, an overview of the known records and an updated distribution map are given and discussed. We rapporteren de vondst van een nieuwe Belgische binnenlandse populatie van de zeldzame loopkever Amara strenua Zimmerman, 1832. Deze soort werd waargenomen tijdens een onderzoek met bodemvallen in Abdij van Park in Heverlee. Deze opmerkelijke vondst telt zowel als de eerste observatie voor Vlaams-Brabant, als de meest binnenlands gekende populatie in Vlaanderen. Gegevens over de habitat en fenologie van deze ontdekte populatie worden gegeven. Verder wordt een overzicht van de gekende records gemaakt en besproken, samen met een aangepaste verspreidingskaart. Résumé Une nouvelle population du rare scarabée terrestre Amara strenua Zimmerman, 1832 est mentionnée en Belgique. L'espèce a été observée lors d'un inventaire à Abdij van Park (Heverlee). Cette observation constitue le premier signalement de l'espèce dans le Brabant flamand et sa localisation la plus à l'intérieur des terres en Flandre. Des informations détaillées sur l'habitat et la phénologie sont fournis. En outre, une carte de distribution actualisée et un compte rendu des observations sont donnés et discutés. Introduction Amara strenua is an 8-10 mm long ground beetle (Carabidae) (Fig. 1). It is characterized by a metallic green or bronze dorsal coloration and trifurcate protibial spur. It can be identified reliably by the unique shape of the male genitalia. A. strenua most closely resembles A. tricuspidata, but can be differentiated by a deeper groove-shaped basal impression on the pronotum and a narrower pronotum posteriorly in A. tricuspidata. The male genitalia of A. strenua are distinctive, missing lateral indentations on the aedeagus (MUILWIJK et al., 2015)
Discovery of a new inland population of Amara strenua Zimmerman, 1832 at Heverlee, central Belgium (Coleoptera: Carabidae)
No full textA new inland population of the rare ground beetle Amara strenua Zimmerman, 1832 is reported for Belgium. This species was encountered during a survey using pitfall traps at Abdij van Park near Heverlee. This observation marks the first record in Flemish Brabant, as well as the most inland known population of A. strenua in Flanders. Details on the habitat and the phenology of the newly discovered population are provided. Furthermore, an overview of the known records and an updated distribution map are given and discussed. We rapporteren de vondst van een nieuwe Belgische binnenlandse populatie van de zeldzame loopkever Amara strenua Zimmerman, 1832. Deze soort werd waargenomen tijdens een onderzoek met bodemvallen in Abdij van Park in Heverlee. Deze opmerkelijke vondst telt zowel als de eerste observatie voor Vlaams-Brabant, als de meest binnenlands gekende populatie in Vlaanderen. Gegevens over de habitat en fenologie van deze ontdekte populatie worden gegeven. Verder wordt een overzicht van de gekende records gemaakt en besproken, samen met een aangepaste verspreidingskaart. Résumé Une nouvelle population du rare scarabée terrestre Amara strenua Zimmerman, 1832 est mentionnée en Belgique. L'espèce a été observée lors d'un inventaire à Abdij van Park (Heverlee). Cette observation constitue le premier signalement de l'espèce dans le Brabant flamand et sa localisation la plus à l'intérieur des terres en Flandre. Des informations détaillées sur l'habitat et la phénologie sont fournis. En outre, une carte de distribution actualisée et un compte rendu des observations sont donnés et discutés. Introduction Amara strenua is an 8-10 mm long ground beetle (Carabidae) (Fig. 1). It is characterized by a metallic green or bronze dorsal coloration and trifurcate protibial spur. It can be identified reliably by the unique shape of the male genitalia. A. strenua most closely resembles A. tricuspidata, but can be differentiated by a deeper groove-shaped basal impression on the pronotum and a narrower pronotum posteriorly in A. tricuspidata. The male genitalia of A. strenua are distinctive, missing lateral indentations on the aedeagus (MUILWIJK et al., 2015)
FIGURE 1 in First record of the West Nile virus bridge vector Culex modestus Ficalbi (Diptera Culicidae) in Belgium, validated by DNA barcoding
No full textFIGURE 1. (A) Posterior part of the mounted Cx. modestus larva. Zoom on the diagnostic characteristic of the siphon, showing disarrayed insertion points of the ventral siphonal setae. (B) Posterior part of a mounted Cx. pipiens larva.Published as part of <i>Wolf, Katrien De, Vanderheyden, Ann, Deblauwe, Isra, Smitz, Nathalie, Gombeer, Sophie, Vanslembrouck, Adwine, Meganck, Kenny, Dekoninck, Wouter, Meyer, Marc De, Backeljau, Thierry, Müller, Ruth & Bortel, Wim Van, 2021, First record of the West Nile virus bridge vector Culex modestus Ficalbi (Diptera Culicidae) in Belgium, validated by DNA barcoding, pp. 131-139 in Zootaxa 4920 (1)</i> on page 134, DOI: 10.11646/zootaxa.4920.1.7, <a href="http://zenodo.org/record/4471790">http://zenodo.org/record/4471790</a>
embalming and reperfusion of porcine kidneys
No full text<p>These are the data of the following article:</p>
<p>Understanding Thiel embalming in pig kidneys to develop a new circulation model</p>
<p>First author: Wouter Willaert</p
Nederland op een kantelpunt: Interview met Wouter Veldhuis over het Stedelijk Netwerk Nederland en het sociaal netwerk van woonwijken
No full textDe stedenbouwkundige en architect Wouter Veldhuis en landschapsarchitect Jannemarie de Jonge zijn per 1 december 2020 Rijksadviseur voor de fysieke leefomgeving. Later in september 2021 komt daar de architect Francesco Veenstra bij als Rijksbouwmeester en dan is het nieuwe trio College van Rijksadviseurs weer compleet. De uitdagingen voor het college zijn groot. De ruimteclaims die er liggen in stad en land, de hooggestemde ambities om klimaatneutraal en circulair te zijn in 2050, de roep om een minister voor de fysieke leefomgeving en of wonen en weer een echt ministerie met budget. Het enorme probleem op de woningmarkt en de druk om één miljoen woningen ergens bij te bouwen. Op 24 april sprak het team van 1M Homes initiative van de TU Delft met de nieuw benoemde rijksadviseur voor de fysieke leefomgeving Wouter Veldhuis over de aanstaande veranderingen
Faunistic, taxonomic and ecological research of ants from the Galápagos Islands with emphasis on invasive species
No full textConflict en coöperatie tussen mieren en met mieren geassocieerde arthropoden
No full textAn intimate association between two species is known as a symbiosis. A symbiotic relationship where both partners benefit is defined as a mutualism. This is in contrast with parasitism, where one partner benefits at the expense of another partner. Commensalism is a third type of symbiotic association and is characterized by one partner that takes advantage of the association and the other is unaffected. These different types of symbioses are widespread in social insects. The largest diversity of social insect symbionts evolved in the group of myrmecophiles, which are arthropods that live inside or in close vicinity of ant nests. Up till now, studies on myrmecophiles focus typically on the association between a host and a single symbiont. In this thesis, ant nests were considered as microcosms with multiple myrmecophiles living together in the same ant nest. We were interested in the biotic and abiotic interactions that affect the symbiotic community as a whole, rather than focusing on single species interactions. In addition, our current knowledge on the symbiosis of arthropods with ants is typically based on very specialized species. Here, we focus on relatively unspecialized myrmecophiles, which probably outnumber the group of specialized species. Our main model system was the myrmecophile microcosm in the nests of red wood ants (Formica rufa group). Our second model system was an association of co- inhabiting (= parabiosis) African ant species that also houses a community of myrmecophile species. In chapter 1, we reviewed the diverse group of myrmecophiles that can be found in association with red wood ants (RWAs). In total, 125 species were listed and the biology of the different arthropod groups were discussed. This chapter serves as an introduction to the later chapters. The main part of this thesis deals with biotic interactions in ant nests, but we examined first in chapter 2 the effect of abiotic interactions on myrmecophile communities. In accordance with metapopulation theory, myrmecophile species richness per unit volume was negatively correlated with increasing nest mound isolation. We did not find support that the abiotic variables mound moisture, pH, mound size and site size affect the myrmecophile community or its species richness. To understand the dynamics of a community in nature, it is essential to have an idea of its trophic interactions. In chapter 4, a surprising complex food web was found In the RWA microcosm, with most myrmecophiles parasitizing on ant brood and ant prey. In addition, multiple trophic predator-prey links among the myrmecophiles were encountered. The results of the stable isotope analyses complemented the findings of direct feeding tests and indicated the existence of multiple trophic levels. The presence of large numbers of parasitic myrmecophiles can impose large costs on RWAs. However, RWAs could indirectly benefit from the intraguild predation of brood parasitic myrmecophiles. In chapter 3, another mechanism that might counter the high parasitic pressure was shown. In general, large foragers in insect colonies specialize in nest defending against large, extranidal threats. However, we demonstrated that small nurses in RWA colonies are the most aggressive and most efficient defenders of brood against small, intranidal, parasitic myrmecophiles. This group of workers is best suited to defend the brood against these parasites due to their better matching size, high encounter rate in the nest and the high task switching costs that would occur if foragers had to carry out this task. The RWA myrmecophiles showed a different level of integration, with some species preferring the dense brood chambers, whereas others avoided the brood chambers and lived at the edge of the nest (chapter 5). This level of integration was not correlated with the aggression they provoked in their RWA host or their brood predation tendency. Up till now, it is believed that social insect symbionts mainly employ chemical deception by either mimicking the host’s cuticular chemical profile (mimicry or camouflage) or being chemical insignificant to sneak into social insect nests. However, in the community of RWA myrmecophiles tested in chapter 6, most species had distinct chemical profiles. Some of them carried low concentrations of compounds, but a significant part showed no disguise at all. These results shed new light on the evolution of integration mechanisms in social insect symbionts, and stresses that unspecialized species can integrate in social insect nests by using simple strategies such as hiding, swift movements or emitting defensive chemicals rather than using chemical deception. Many RWA myrmecophiles are persecuted, but in chapter 7 we reported that survival of three obligate myrmecophilous beetles over a period of 20 days was not different from a control set-up without ants. However, reduced survival was detected for a facultative myrmecophile in presence of RWAs. Survival analyses in the presence of 9 different ant species showed that the three beetles survived better in presence of larger-bodied ant species, and was highest in presence of its preferred host F. rufa, which also has relatively large workers. These results suggests, that in spite of their unspecialized nature, these beetles are optimally adapted to their preferred host and the importance of size asymmetries in host-symbiont interactions. Finally, the interactions in the parabiotic nests of the large Platythyrea conradti and tiny Strumigenys maynei ants were described in chapter 8. The chemical profile of the parabiotic partners was very different. The parabiotic association tended to be mutualistic as P. conradti benefits from the supreme defence capabilities of S. maynei against alien ants and intranidal myrmecophiles. The latter, in turn, benefits from the prey that thrive in the organic material carried to the nest by P. conradti.status: Publishe
Does Indonesia have a"low-pay"civil service?
No full textGovernment officials and polcy analysts maintain that Indonesia's civil servants are poorly paid and have been for decades. This conclusion is supported by anecdotal evidence and casual empiricism. The authors systematically analyze the realtionship between government and private compensation levels using data from two large household surveys carried out by Indonesia's Central Bureau of Statistics: the 1998 Sakernas and 1999 Susenas. The results suggest that government workers with a high school education or less, representing three-quarters of the civil service, earn a pay premium over their private sector counterparts. Civil servants with more than a high school education earn less than they would in the private sector but, on average, the premium is far smaller than commonly is alleged and is in keeping with public/private differentials in other countries. These results prove robust to varying econometric specifications and cast doubt on low pay as an explanation for government corruption.Decentralization,Public Health Promotion,Health Monitoring&Evaluation,National Governance,Knowledge Economy,Health Monitoring&Evaluation,NationalGovernance,Knowledge Economy,Education for the Knowledge Economy,Parliamentary Government
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