University of Twente Publications
University of Twente Repository provides publications of UT scientific staff, in many cases full text and publicly available.
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A two-echelon spare parts network with lateral and emergency shipments: A product-form approximation - Boucherie, Richard J.; Houtum, Geert-Jan van; Timmer, Judith; Ommeren, Jan-Kees van
We consider a single-item, two-echelon spare parts inventory model for repairable parts for capital goods with high down time costs. The inventory system consists of a central warehouse and multiple local warehouses, from where customers are served, and a central repair facility at an external supplier. When a part fails at a customer, his request for a ready-for-use part is immediately fullled by his local warehouse if it has a part on stock. At the same time, the failed part is sent to the central repair facility for repair. If the local warehouse is out of stock, then, via an...
Effect of temporal stimulus properties on the nociceptive detection probability using intra‑epidermal electrical stimulation - Doll, Robert J.; Maten, Annefloor C.A.; Spaan, Sjoerd P.G.; Veltink, Peter H.; Buitenweg, Jan R.
Chronic pain disorders can be initiated and maintained by malfunctioning of one or several mechanisms underlying the nociceptive function. Although several quantitative sensory testing methods exist to characterize the nociceptive function, it remains difficult to distinguish the contributions of individual mechanisms. Intra-epidermal electrical stimulation of nociceptive fibers allows defining stimuli with temporal properties within the timescale of these mechanisms. Here, we studied the effect of stimulus properties on the psychophysical detection probability. A psychophysical detection experiment was conducted including 30 healthy human participants. Participants were presented with electrical stimuli having various temporal properties. The pulse-width was varied for single pulse...
Mobile health systems and emergence - Jones, Valerie M.
Changes in the age distribution of the population and increased prevalence of chronic illnesses, together with a shortage of health professionals and other resources, will increasingly challenge the ability of national healthcare systems to meet rising demand for services. Large-scale use of eHealth and mHealth services enabled by advances in ICT are frequently cited as providing part of the solution to this crisis in future provision. As part of this picture, self-monitoring and remote monitoring of patients, for example by means of smartphone apps and body-worn sensors, is on the way to becoming mainstream. In future, each individual’s personal health...
Ion and surfactant induced wetting transition - Bera, Bijoyendra
One of the major challenges of modern society is the increasing demand for energy, and conventional resources such as oil and natural gas are crucial for meeting this challenge. Hence it is of paramount importance to enhance the recovery process of these resources with a sustainable and environment-friendly approach. An incremental oil-output from the reservoir is achieved via Enhanced Oil Recovery (EOR). This thesis focuses on one of these processes, namely wettability alteration, where turning a oil-wet reservoir-rock into a waterwet surface releases oil droplets and ensures an incremental recovery.
First, we investigate the competitive wetting of aqueous salt solution and...
Automotive security functions: the use of new technologies to tackle vehicle-related crime - Knapik, Peter
New technologies are mainly used in academia and industry to advance applications in three categories within the automotive field. The first category involves applications to improve traffic efficiency. The second set of applications aims to provide the driver and passengers with infotainment features. The last category consists of assistance functions which nowadays are the main reason for the increasing penetration of technologies in the automotive field.
Until now, existing countermeasures dealing with vehicle-related crime have mostly concentrated on the vehicle itself and focus on physical target hardening. As a result they do not involve other elements, like vehicles, occupants and infrastructure,...
Predicting turnaround time reductions of the diagnostic track in the histopathology laboratory using mathematical modelling - Leeftink, A.G.; Boucherie, R.J.; Hans, E.W.; Verdaasdonk, M.A.M.; Vliegen, I.H.M.; Diest, P.J. van
Background Pathology departments face a growing volume of more and more complex testing in an era where healthcare costs tend to explode and short turnaround times (TATs) are expected. In contrast, the histopathology workforce tends to shrink, so histopathology employees experience high workload during their shifts. This points to the need for efficient planning of activities in the histopathology laboratory, to ensure an equal division of workload and low TATs, at minimum costs.
Methods The histopathology laboratory of a large academic hospital in The Netherlands was analysed using mathematical modelling. Data were collected from the Laboratory Management System to determine...
Excellence in higher education: educational preferences of honours students in the Netherlands - Kolster, Renze; Dijk, Lisa van; Jongbloed, Ben
This paper researches excellence in higher education by looking into honours programmes (HPs) in Dutch higher education. HPs are selective and aimed at the brightest students, offering them a more challenging – often extra-curricular – study experience. Based on a survey (n=259) at Dutch universities, our study identifies three types of honours students: task-committed, above-average ability, and creative. We asked each group how their ideal HP looks like. Task-committed students are interested in disciplinary HPs that have a student-centred approach. The above-average ability students demand a highly selective and small-scale HP that admits only the brightest students. Moreover, they prefer...
Overheidsparticipatie in sociale media - Dijk, Jan A.G.M. van; Wijngaert, Lidwien van de; Tije, Sanne ten
Het gebruik van sociale media is in korte tijd sterk gegroeid onder brede lagen van de bevolking. In de afgelopen jaren heeft de overheid al de nodige ervaring opgedaan met sociale media. De vraag die nu voorligt heeft betrekking op een actieve rol van de overheid op sociale media: Wat zijn de mogelijkheden en beperkingen van overheidsparticipatie in sociale media? Om antwoord te geven op deze vraag is het van belang inzicht te krijgen in de technologie achter sociale media, de toepassingen, strategieën en tactieken. Deze inzichten zijn verkregen uit een literatuuronderzoek en een achttal cases waarin sociale media op...
The influence of prosocial norms and online network structure on prosocial behavior: an analysis of movember’s twitter campaign in 24 countries - Broek, Tijs van den; Need, Ariana; Ehrenhard, Michel; Priante, Anna; Hiemstra, Djoerd
Sociological research points at norms and social networks as antecedents of prosocial behavior. To date, the literature remains undecided on how these factors jointly influence prosocial behavior. Furthermore, the use of social media by campaign organizations may change the need for formal networks to organize large-scale collective action. Hence, in this paper we examine the interplay of prosocial norms and the structure of online social networks on offline prosocial behavior. For this purpose we use donation data from the global Movember campaign, messages about the Movember campaign on the online social networking site Twitter, and data from the World Giving...
Evidence combination for incremental decision-making processes - Berrada, Ghita; Keulen, Maurice van; Keijzer, Ander de
The establishment of a medical diagnosis is an incremental process highly fraught with uncertainty. At each step of this painstaking process, it may be beneficial to be able to quantify the uncertainty linked to the diagnosis and steadily update the uncertainty estimation using available sources of information, for example user feedback, as they become available. Using the example of medical data in general and EEG data in particular, we show what types of evidence can affect discrete variables such as a medical diagnosis and build a simple and computationally efficient evidence combination model based on the Dempster-Shafer theory.
On the impact of Twitter-based health campaigns: a cross-country analysis of movember - Dwi Prasetyo, N.; Hauff, C.; Nguyen, Dong-Phuong; van den Broek, T.; Hiemstra, D.
Health campaigns that aim to raise awareness and subsequently raise funds for research and treatment are commonplace. While many local campaigns exist, very few attract the attention of a global audience. One of those global campaigns is Movember, an annual campaign during the month of November, that is directed at men’s health with special foci on cancer & mental health. Health campaigns routinely use social media portals to capture people’s attention. Recently, researchers began to consider to what extent social media is effective in raising the awareness of health campaigns. In this paper we expand on those works by conducting...
#SupportTheCause: Identifying Motivations to Participate in Online Health Campaigns - Nguyen, Dong-Phuong; Broek, Tijs van den; Hauff, Claudia; Hiemstra, Djoerd; Ehrenhard, Michel
We consider the task of automatically identifying participants’ motivations in the public health campaign Movember and investigate the impact of the different motivations on the amount of campaign donations raised. Our classification scheme is based on the Social Identity Model of Collective Action (van Zomeren et al., 2008). We find that automatic classification based on Movember profiles is fairly accurate, while automatic classification based on tweets is challenging. Using our classifier, we find a strong relation between types of motivations and donations. Our study is a first step towards scaling-up collective action research methods.
Audience and the use of minority languages on Twitter - Nguyen, Dong-Phuong; Trieschnigg, Dolf; Cornips, Leonie
On Twitter, many users tweet in more than one language. In this study, we examine the use of two Dutch minority languages. Users can engage with different audiences and by analyzing different types of tweets, we find that characteristics of the audience influence whether a minority language is used. Furthermore, while most tweets are written in Dutch, in conversations users often switch to the minority language.
Stairwalker user manual - Muller, Dennis; Elsinga, Jochem; Keulen, Maurice van
Geographical data are typically visualized using various information layers that are displayed over a map. Interactive exploration by zooming and panning actions needs real-time re-calculation. A common operation in calculating with multidimensional data is the computation of aggregates. For layers containing aggregated information derived from voluminous data sets, such real-time exploration is impossible using standard database technology. Calculations require too much time.
The University of Twente has developed “Stairwalker”: database technology that accurately aggregates data so that they can geographically be explored in real-time. The technology is a plug-in to common open source technology.
Its core is the pre-aggregate index: a database...
Chondrocytes co-cultured with Stromal Vascular Fraction of adipose tissue present more intense chondrogenic characteristics than with Adipose Stem Cells - Wu, L.; Prins, H.J.; Leijten, J.C.H.; Helder, M.; Evseenko, D.; Moroni, L; Blitterswijk, C.A. van; Lin, Y.; Karperien, H.B.J.
Partly replacement of chondrocytes by stem cells has been proposed to improve the performance of autologous chondrocytes implantation (ACI). Our previous studies showed that the increased cartilage production in pellet co-cultures of chondrocytes and mesenchymal stem cells (MSCs) is due to a trophic role of the MSC by stimulating chondrocyte proliferation and matrix production rather than MSCs actively undergoing chondrogenic differentiation. The aim of this study is to compare the trophic effects of stromal vascular fraction cells (SVF) and in vitro expanded adipose stem cells (ASC). SVF and culture expanded ASCs (n =9) were co-cultured with primary human chondrocytes in...
In Vitro Evaluation of Spider Silk Meshes as a Potential Biomaterial for Bladder Reconstruction - Steins, A.; Dik, P.; Müller, W.H.; Vervoort, S.J.; Reimers, K.; Kubhier, J.W.; Vogt, P.M.; Apeldoorn, A.A. van; Coffer, P.J.; Schepers, K.
Reconstruction of the bladder by means of both natural and synthetic materials remains a challenge due to severe adverse effects such as mechanical failure. Here we investigate the application of spider major ampullate gland-derived dragline silk from the Nephila edulis spider, a natural biomaterial with outstanding mechanical properties and a slow degradation rate, as a potential scaffold for bladder reconstruction by studying the cellular response of primary bladder cells to this biomaterial. We demonstrate that spider silk without any additional biological coating supports adhesion and growth of primary human urothelial cells (HUCs), which are multipotent bladder cells able to differentiate...
Macromolecular Engineering of In-Situ Forming Hydrogels - Wang, Rong
Surgery in our perspective generally requires an operation with a certain size of an
incision, leaving wounds, which are painful, require a long time to heal and end up with
the formation of scars. Advances in medical procedures and technologies have led to the
development of minimally invasive surgical procedures and several imaging tools for
diagnosis. Imaging by techniques like e.g. Magnetic Resonance Imaging (MRI) has
become increasingly important since it provides 3D-information in a non-invasive
manner . If possible, in follow-up surgery, a minimally invasive procedure with a small
incision is applied because of the time reduction for a wound to heal and of prime