Spectral properties of birth-death polynomials - Doorn, Erik A. van
We consider sequences of polynomials that are defined by a three-terms recurrence relation and orthogonal with respect to a positive measure on the nonnegative axis. By a famous result of Karlin and McGregor such sequences are instrumental in the analysis of birth-death processes. Inspired by problems and results in this stochastic setting we present necessary and sufficient conditions in terms of the parameters in the recurrence relation for the smallest or second smallest point in the support of the orthogonalizing measure to be larger than zero, and for the support to be discrete with no finite limit point.
ADAPTER: Analysing & Developing Adaptability & performance in Teams to enhance resilience - Beek, Dolf (F.A.) van der; Schraagen, Jan Maarten
In the current study, the concept of team resilience was operationalized by developing a first version of a questionnaire (ADAPTER) driven by the four essential abilities of resilience (Hollnagel, 2011) and expanded with more relation-oriented abilities of leadership and cooperation. The development and administration of ADAPTER took place within two companies. Factor analyses using data of 91 participants largely supported the hypothesized 6-dimension taxonomy. Support was found for Team responding behavior, Shared Leadership and Cooperation with other teams/ departments. Anticipation showed considerable overlap with the Monitoring scale, possibly due to the fact that monitoring items dealt with prospective situations. Using...
Teachers' knowledge sharing: a study on the influence of work engagement, occupational self-efficacy and Human Resources Management on knowledge sharing - Vermeulen, M.; Runhaar, P.; Konermann, J.; Sanders, Karin
Knowledge sharing is one of the professionalizetion processes and is an important factor in the competition between organizations and for innovation processes to sustain. In this study the central theme is the way knowledge sharing is affected by occupational self-efficacy (OSE), work engagement and High Commitment HRM (HC-HRM). In investigating these relations the AMO framework is used. The research data were obtained by 126 teachers from one secondary school. However from the regression analyses it was learned that the relationship between the variables OSE, HC HRM and work engagement with knowledge sharing was more complex than expected. Additional analyses by...
Working mechanism of a multidimensional computerized adaptive test for fatigue in rheumatoid arthritis - Nikolaus, Stephanie; Bode, Christina; Taal, Erik; Vonkeman, Harald E.; Glas, Cees A.W.; Laar, Mart A.F.J. van de
This paper demonstrates the mechanism of a multidimensional computerized adaptive test (CAT) to measure fatigue in patients with rheumatoid arthritis (RA). A CAT can be used to precisely measure patient-reported outcomes at an individual level as items are consequentially selected based on the patient’s previous answers. The item bank of the CAT Fatigue RA has been developed from the patients’ perspective and consists of 196 items pertaining to three fatigue dimensions: severity, impact and variability of fatigue.
The CAT Fatigue RA was completed by fifteen patients. To test the CAT’s working mechanism, we applied the flowchart-check-method. The adaptive item selection...
Modeling habitual and addictive smartphone behavior: The role of smartphone usage types, emotional intelligence, social stress, self-regulation, age, and gender - Deursen, Alexander J.A.M. van; Bolle, Colin L.; Hegner, Sabrina M.; Kommers, Piet A.M.
The present study investigates the role of process and social oriented smartphone usage, emotional intelligence, social stress, self-regulation, gender, and age in relation to habitual and addictive smartphone behavior. We conducted an online survey among 386 respondents. The results revealed that habitual smartphone use is an important contributor to addictive smartphone behavior. Process related smartphone use is a strong determinant for both developing habitual and addictive smartphone behavior. People who extensively use their smartphones for social purposes develop smartphone habits faster, which in turn might lead to addictive smartphone behavior. We did not find an influence of emotional intelligence on...
Exploring teachers' use of TPACK in design talk: The collaborative design of technology-rich early literacy activities - Boschman, Ferry; Mckenney, Susan; Voogt, Joke
Research shows the benefits of collaborative design activity by teachers are that in their conversations (design talk) they develop technological pedagogical content knowledge (TPACK). While more and more teachers engage in collaborative design, little is known about how they use TPACK during design. The main question of this study was: “What is the nature of design talk of a group of teachers during the design of technology-rich early literacy activities?” Using a holistic case study on design talk, the analysis focused on the topics that were under discussion and how these topics were discussed. Three phases of coding were applied:...
Advantages of electrostatic spring hardening in biomimetic hair flow sensors - Droogendijk, Harmen; Boer, Meint J. de; Sanders, Remco G.P.; Krijnen, Gijs J.M.
We report on a fully adaptable flow sensor with adjustable detection limit, responsivity, range, and bandwidth by addition of electrostatic spring hardening (ESH) to our previously developed microelectromechanical systems hair flow sensors. The sensor's mechanical transfer shows large voltage-controlled electromechanically affected responsivity for frequencies below the sensor's resonance. Using capacitive readout, a bias voltagecontrolled sensory threshold is obtained, giving a threefold tunable ac-airflow detection threshold (down to 0.3 mms-1). The mechanism of spring control also extends to dc-flows, as shown for the first time; electrostatic spring hardening allows to increase the dc-flow measurement range by almost a factor 2, up...
Nanopore fabrication by heating au particles on ceramic substrates - Vreede, Lennart J. de; Berg, Albert van den; Eijkel, Jan C.T.
We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter congruent to 25 nm, length up to 800 nm). The process can be understood as driven by gold evaporation and controlled by capillary forces and can be controlled by temperature programming and substrate choice.
Cyclohexane selective photocatalytic oxidation by anatase TiO2: influence of particle size and crystallinity - Carneiro, Joana T.; Almeida, Ana R.; Moulijn, Jacob A.; Mul, Guido
A systematic study is presented on the effect of crystallite size of Anatase (Hombikat, Sachtleben), varied by calcination at different temperatures up to 800 °C, on photocatalytic activity in cyclohexane selective oxidation. Two different reactors were used to test the materials: a top illumination reactor and an in situ ATR-FTIR cell. Properties such as crystallinity and associated availability of holes and electrons for surface reactions, as well as the amount of surface OH-groups, are shown to have a significant influence on TiO2 activity, (surface) selectivity, and stability. Upon increasing the crystallite size, productivity (g−1catalyst) decreases, while (i) the TOF (moles...
Characterization of Fe sites in Fe-zeolites by FTIR spectroscopy of adsorbed NO: are the spectra obtained in static vacuum and dynamic flow set-ups comparable? - Berlier, Gloria; Lamberti, Carlo; Rivallan, Mickael; Mul, Guido
The present paper shows a direct comparison of IR spectra of adsorbed NO on two catalyst systems (Fe-silicalite and Fe-ZSM-5), recorded in a flow-through cell (in operando, where NO is carried by an excess of inert gas) and static cell (in situ, where a given pure NO equilibrium pressure is dosed). A progressive NO poly-adsorption is observed in the static cell upon increasing the NO equilibrium pressure (from Fe2+(NO)2 to Fe2+(NO)3), while predominantly Fe2+NO adducts are observed in the flow-through cell. By comparing literature spectra, it is shown that these spectral differences are intrinsically inherent to the two different experimental...
Improved performance of TiO2 in the selective photo-catalytic oxidation of cyclohexane by increasing the rate of desorption through surface silylation - Almeida, Ana Rita; Carneiro, Joana T.; Moulijn, Jacob A.; Mul, Guido
The effect of silylation on the performance of an anatase TiO2 catalyst in the selective photo-oxidation of cyclohexane was investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and an illuminated slurry reactor. The rate of cyclohexanone formation showed a dependency on the availability of surface active OH sites and on the desorption rate of cyclohexanone. Two classes of catalysts could be identified: (1) containing less than 1.0 wt.% Si where the cyclohexanone formation rate is decreased by silylation due to a decrease in OH availability and (2) containing more than 1.0 wt.% Si where the improved desorption rate...
Mechanistic study of hydrocarbon formation in photocatalytic CO2 reduction over Ti-SBA-15 - Yang, Chieh-Chao; Vernimmen, Jarian; Meynen, Vera; Cool, Pegie; Mul, Guido
Ti-SBA-15 was exposed to illumination in the presence of different gas mixtures containing CO or CO2, and H2O or H2, in order to clarify the route to hydrocarbon formation in photocatalytic CO2 reduction over this photocatalyst. A mixture of CO and H2O led to the highest quantities of CH4, C2H4, and C2H6 after 7 h of reaction, whereas a mixture of CO2 and H2 lead to the lowest production rate of these products. H2O has been identified as more efficient in activation of CO and CO2 than H2. CH3OH was not detected as significant product, and when fed to the...
Efficient NO adsorption and release at Fe3+ sites in Fe/TiO2 nanoparticles - Wu, Qingping; Mul, Guido; Krol, Roel van de
The adsorption and release of nitrogen oxide (NO) molecules at the surface of Fe-doped TiO2 nanoparticles, made by a template-free sol–gel process, has been studied. Fe3+ ions are found to be highly effective NO adsorption sites in Fe/TiO2. Up to [similar]89 μmol g−1 of the adsorbed NO can be released by exposure to trace amounts of H2O, which exceeds the water-induced release capacity of other NO storage materials by at least a factor of 2. The surprising efficiency of water as a trigger molecule for NO release is due to its large dipole moment, which causes a much stronger coordination...
Docentontwikkelteams en de professionalisering van docenten - Coenders, Fer
Vakinhoudelijke en -didactische vernieuwingen landen vaak maar moeizaam in scholen, doordat
leraren nauwelijks betrokken zijn bij het discours binnen hun vakgebied. Docentontwikkelteams
(DOT’s) kunnen een rol vervullen als schakel tussen vakvernieuwing en de implementatie ervan in de school. Vakdidacticus Fer Coenders beschrijft aan de hand van de recente vernieuwing van het
scheikundeonderwijs, hoe je zo’n DOT kunt opzetten en wat het oplevert.