310 research outputs found
Microstructure and properties of duplex coatings on magnesium alloy
No full textThe duplex Ti cold spray + MAO coatings were deposited on the Mg alloy substrates using combined cold spray and micro arc oxidation (MAO). The microstructure, mechanical property and corrosion resistance of the duplex coatings were investigated compared with the MAO coated Mg alloy substrate. Results indicate that the Ti cold spray coating with 130 mu m showed an obvious boundary between the Mg substrate, and the TiO2 phase was formed by MAO on the top coating. The duplex coating showed a little coarse and porous structure, which resulted in low mechanical property and wear resistance compared with the MAO treated Mg substrate. However, it showed an excellent corrosion resistance due to the difference of chemical stability for the coatings. Furthermore, this duplex coating might be very useful for improving the photocatalytic ability of titania due to its markedly increasing specific area
Investigation of the initial stage of Mandarin tones acquisiton by Australian university students
No full textEpidemiology and burden of soil-transmitted helminth infections among school-aged Bulang children in Yunnan province, People's Republic of China
No full textBackground: The three most common soil-transmitted helminths are Ascaris lumbricoides (roundworm), Trichuris trichiura (whipworm), and Ancylostoma duodenale and Necator americanus (hookworms). Collectively, they infect around 1 billion people and put approximately 5 billion people at risk of infection worldwide. Strongyloides stercoralis is a less common soil-transmitted helminth than the species mentioned above, but still significant from a public health perspective. The global prevalence of S. stercoralis is estimated to be 30-100 million. Populations most affected by these parasitic worms are often impoverished, living on less than US$ 2 per day, and have poor sanitation facilities and hygiene habits. Despite the low prevalence levels of soil-transmitted helminth infections observed on a national level in the People’s Republic of China (P.R. China), hotspots of these infections, particularly within ethnic minority groups residing in rural areas, still exist.
Single-species infections with the common soil-transmitted helminths can cause symptoms ranging from abdominal pain to anaemia, and impaired development of cognitive abilities. For S. stercoralis infections, symptoms such as severe abdominal pain and blood in the stool have been reported. Due to the chronic and subtle nature of most morbidities commonly associated with soil-transmitted helminthiasis, it is difficult to assess the true burden due to these infections.
Objectives: The goal guiding this Ph.D. project was to deepen the understanding of the epidemiology and burden of soil-transmitted helminthiasis among school-aged children from the Bulang ethnic minority group in P.R. China. The following objectives were pursued: (i) to evaluate the feasibility of deploying different tools for the assessment of physical fitness in soil-transmitted helminth-endemic settings; (ii) to monitor changes in physical fitness, strength and anthropometric measurements over a six-month period among treated children and their untreated peers; (iii) to predict and visualize the change in physical fitness of school-aged children due to soil-transmitted helminth infections over a 1-month period across P.R. China; (iv) to assess the efficacy of triple-dose albendazole and study soil-transmitted helminth re-infection patterns after deworming; and (v) to estimate the odds of re-infection with soil-transmitted helminths for different natural nutritional statuses and types of nutritional supplementation.
Methods: For the field studies, parasitological examination of stool samples was performed. The Kato-Katz technique was used to identify the eggs of A. lumbricoides, hookworm, T. trichiura and other helminths, while the Baermann technique was used to identify the larvae of S. stercoralis. In addition, each stool sample was visually inspected for Taenia spp. proglottids. Physical fitness was estimated with the 20-m shuttle run test and physical strength was assessed with the grip strength and standing broad jump tests. Anthropometric measurements, including body height and weight and sum of skinfolds, and haemoglobin level were also recorded. Physical fitness and strength scores, anthropometric measurements, and haemoglobin level were expressed as means, and compared among children of distinct soil-transmitted helminth infection status and intensity. For the prediction and visualization exercise, the change in physical fitness over 1 month across P.R. China was predicted over a smooth surface of soil-transmitted helminth risk. Maps, with lower and upper boundaries of the predicted values as well as population-adjusted estimates, were further created. Finally, for the systematic review, the odds of re-infection with soil-transmitted helminths for different natural nutritional statuses and types of nutritional supplementation were estimated and qualitative content analysis was conducted for all studies included in the review.
Results: In a cross-sectional survey, the maximum aerobic capacity in 1 min of exhaustive exercise (VO2 max estimate) of T. trichiura-infected children was 1.9 ml kg-1 min-1 lower than that of their non-infected counterparts (P=0.01). Until exhaustion, T. trichiura-infected children had completed six 20-m laps less (P<0.01). No significant association between anthropometric indicators and infection with any soil-transmitted helminth species could be established.
In a randomised controlled trial, which investigated the effects of triple-dose albendazole on physical fitness of school-aged children, baseline prevalences of T. trichiura, A. lumbricoides, hookworm, and S. stercoralis were 94.5%, 93.3%, 61.3%, and 3.1% respectively, with more than half harboring triple-species infections. During the course of the trial, rapid re-infection with A. lumbricoides was observed and low cure rate was achieved with T. trichiura infections. Children receiving triple-dose albendazole scored slightly higher values in physical fitness and strength scores, anthropometric measurements, and haemoglobin level than placebo recipients, but the difference lacked statistical significance. The increase in VO2 max estimate from baseline was 1.6 ml kg-1 min-1 (P=0.02) less and the increase in the number of 20-m laps completed from baseline was five 20-m laps (P=0.04) less for T. trichiura-infected children compared to their non-infected peers. In addition, children with low infection intensity of T. trichiura and hookworm had consistently more increase in the VO2 max estimate from baseline than their peers with high infection intensity of all soil-transmitted helminths (range: 1.9-2.1 ml kg-1 min-1; all P <0.05).
In the systematic review, multi-micronutrients seemed to have the clearest effect with regards to lowering re-infection rates and intensity of soil-transmitted helminths, whereas consumption of zinc or vitamin A alone might have a negative impact on these two outcomes measures. With regards to the natural nutrition status of the host, the general trend observed was that individuals with poor nutrition status suffered higher re-infection rates and intensities when compared to their well-nourished peers. Overall, only fifteen studies met our inclusion criteria and majority of them were of low quality.
Conclusions/significance: The negative associations observed between T. trichiura infections and physical fitness among school-aged Bulang children in Yunnan suggests that the current burden estimate of soil-transmitted helminth infections, in particular T. trichiura infections, might be underestimated and there are still subtle and hidden morbidities to be quantified. A paradigm shift is needed to further understand the burden of soil-transmitted helminth infections as the presence of co-infections and co-morbidities add layers of complexity to the task. Finally, the epidemiological findings on soil-transmitted helminthiasis from this thesis highlight that a national soil-transmitted helminth control programme is overdue and urgently needed as P.R. China further develops into a global powerhouse. With many of their rural communities starting to have their hands on the first rung of the development ladder, P.R. China seems to be in a good position to set a leading example on how to control and eliminate soil-transmitted helminthiasis, and possibly other neglected tropical diseases, for developing countries around the world
The influence of superimposed DC current on electrical and spectroscopic characteristics of HiPIMS discharge
No full textThe electrical characteristics and spectroscopic properties have been comprehensively investigated in a DC superimposed high power impulse magnetron sputtering (DC-HiPIMS) deposition system in this paper. The influence of superimposed DC current on the variation of target and substrate currentw aveforms, active species and electron temperatures with pulse voltages are focused. The peak target currents in DC-HiPIMS are lower than in HiPIMS. The time scales of the two main discharge processes like ionization and gas rarefaction in DC-HiPIMS are analyzed. When the pulse voltage is higher than 600 V, the gas rarefaction effect becomes apparent. Overall, the ionization process is found to be dominant in the initial similar to 00 mu s during each pulse. The active species of Ar and Cr in DC-HiPIMS are higher than in HiPIMS unless that the pulse voltage reaches 900 V. However, the ionization degree in HiPIMS exceeds that in DC-HiPIMS at around 600 V. The electron temperature calculated by modified Boltzmann plot method based on corona model has a precipitous increase from 0.87 to 25.0 eV in HiPIMS, but varies mildly after the introduction of the superimposed DC current. Additionally, the current from plasma flowing to the substrate is improved when a DC current is superimposed with HiPIMS. (c) 2018 Author(s)
Peiling nationale kennisbehoefte straling en nucleaire veiligheid
No full textIn a report issued in 2008, the Health Council of the Netherlands noted that the scientific knowledge on radiation protection was seriously in decline. This statement is still valid nowadays. It is therefore important to collate existing radiation knowledge, to make state-of-the-art expertise available to government and society and to acquire more knowledge. This is the main conclusion of a survey, conducted in 2018, to measure the national knowledge requirements for the fields of radiation protection, nuclear safety and security. The majority of people that responded to the survey found it not only important to retain a decent level of knowledge of the subject matter, but they also pointed out that there is a growing demand for knowledge and tools to improve the dialogue with the public on these matters. The respondents were of the opinion that the public’s knowledge of radiation and its (dis)advantages is generally very poor. They mentioned two ways to improve this: (1) through appropriate education, from elementary school to vocational training, and (2) by providing easily accessible knowledge suited for various target groups. An independent Knowledge Centre, with ties to organisations with different perspectives on the subject, could realize the latter. They also took the view that the international scientific position of the Netherlands is insufficient in the fields of radiation protection, nuclear safety and security: they recommended that the Netherlands should distinguish itself internationally on a few carefully chosen research topics. These findings were drawn from the results of a questionnaire, distributed in 2017-2018 under a heterogeneous group of approximately hundred people with senior level involvement in these matters. The questionnaire was designed by a joint working group from the Technical University Delft (TUD), the National Institute for Public Health and the Environment (RIVM) and the Netherlands Forensic Institute (NFI), in response to a request from a group of stakeholders from the nuclear industry, the medical world, the government, knowledge institutes and emergency response agencies. More than 50 people responded to the questionnaire. The preliminary results were discussed within a small group of respondents with various backgrounds. The final results of this survey, as described in this report, form an appropriate starting point for a programme of improvement, which has yet to be established. Safety and Security Scienc
Eigen Huis Marktindicator: 1e kwartaal 2024
No full textDe 80ste peiling van de Eigen Huis Marktindicator (eerste kwartaal 2024) betekent dat we inmiddels over een periode van maar liefst 20 jaar inzicht hebben in het vertrouwen in de koopwoningmarkt onder de Nederlandse woonconsumenten. Een, ook internationaal, uniek inzicht in hoe consumenten de omstandigheden op de koopwoningmarkt ervaren, waarvoor we Vereniging Eigen Huis bedanken als initiatiefnemer en opdrachtgever voor dit langlopend onderzoeksproject. Maar liefst 240 maandelijkse metingen zijn er al uitgevoerd onder een steeds representatieve groep van bijna 700 personen uit hun onderzoekspanel. Er wordt dan ook veelvuldig gerefereerd aan de Eigen Huis Marktindicator in beschouwingen over en onderzoek naar de ontwikkelingen op de woningmarkt!Deze meest recente peiling laat zien dat de score op de Marktindicator, na ruim twee jaar van (lichte) daling, blijft oplopen. Het vertrouwen in de koopwoningmarkt onder de woonconsumenten stijgt in het eerste kwartaal van 2024 namelijk voor de derde opeenvolgende keer ten opzichte van het voorafgaande kwartaal. De score op de Marktindicator neemt in het eerste kwartaal van 2024 met een score ’88,9’ fors toe ten opzichte van de score ’81,1’ in het vorige kwartaal (zie ook figuur 1). Vooral de door de woonconsumenten ingeschatte meer gunstige koopprijsontwikkeling (lees stijgende prijzen) en de door hen ervaren en verwachte stabilisatie of daling van de rente lagen aan deze recente stijging ten grondslag. Dit heeft een duidelijk positief effect gehad op het sentiment van de woonconsument.Real Estate Managemen
Practical equivalence inference as a model building strategy, with applications in multiple comparisons /
No full textVerzorgingstehuis of een alternatief?: De mening van ouderen over een woon- en zorgvoorziening in Leiden-Noord
No full textDe realisering van het nieuw te bouwen verzorgingstehuis Zijloever in Leiden-Noord verkeert al jaren in een impasse. Eind 1986 ontstond een mogelijkheid iets aan de oplossing van dit probleem te doen. Die oplossing zou dan dienen in te spelen op nieuwe zorginhoudelijke ideeën, waardoor meer mogelijkheden voor langer zelfstandig wonen geschapen worden. Een ambtelijke werkgroep 'Alternatief Zijloever' is aan de slag gegaan en heeft modellen ontworpen voor een woon- en zorgvoorziening als alternatief voor het verzorgingstehuis. Ook heeft de werkgroep van begin af aan uitgesproken dat de wijkbewoners bij de ideeënontwikkeling moeten worden betrokken. Het RIW is benaderd om de meningen van ouderen in Leiden-Noord te peilen. Vanwege de geringe tijd die beschikbaar is, heeft het RIW het ROV bij de peiling betrokken met als taak de woon-, leef- en zorgverleningssituatie in Leiden in kaart te brengen. Om voorlichtingsbijeenkomsten en meermalige groepsgesprekken met ouderen in een zeer korte tijd goed te organiseren was de medewerking van het Gecoördineerd Bejaardenwerk in Leiden-Noord onontbeerlijk. Op deze plaats bedanken we Marian Boer en Daan Ike die met grote inzet dit werk verricht hebben. Er waren drie maanden beschikbaar voor dit onderzoek. Deze periode was net voldoende om een indicatief beeld te krijgen. Want de peiling onder ouderen betekent behalve het interviewen van individuele ouderen, het houden van meermalige groepsgesprekken. Dat vergt nogal wat van de betrokken ouderen: ze hebben er veel tijd en energie ingestoken om ons te vertellen wat ze vinden van de situatie in Leiden-Noord en van de modellen van de ambtelijke werkgroep. We hebben dan ook grote waardering voor hun inzet bij deze meningspeiling
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