14 research outputs found
Binaural application of microphone arrays for improved speech intelligibility in a noisy environment
No full textApplied Science
Hearing aid comprising an array of microphones
No full textHearing aid for improving the hearing ability of the hard of hearing, comprising an array of microphones, the electrical output signals of which are fed to at least one transmission path belonging to an ear. Means are provided for deriving two array output signals from the output signals of the microphones, the array having two main sensitivity directions running at an angle with respect to one another and each of which is associated to an array output signal. Each array output signal is fed to its own transmission path belonging to one ear of a person who is hard of hearing.Applied Science
Investigations on resolution enhancement in EPR by means of electron spin echoes
No full textApplied Science
The Water Efficiency Paradox: The significance of spatial scale and knowledge exchange in irrigation water management
No full textWater scarcity is a growing issue across the globe (Rijsberman, 2006) and because agriculture is the main consumer of water, investing in irrigation efficiency seems like a good solution to this problem. However, local gains in efficiency can reduce runoff and hence, have an adverse effect on downstream water availability (o.a. Perry (2018, 1999) and Simons et al. (2015)). The core of the water efficiency paradox lies in the positive connotation of efficiency, even though increasing irrigation efficiency can have negative consequences. On this paradox and how basin analysis can be included in World Bank financed irrigation projects. This is done in two parts.The first part of this research looks into irrigation water consumption in the Amu Darya river basin in Central Asia. With the research question: ‘To what extent is it possible to analyze irrigation water consumption in Central Asia using a locally developed model combined with open source remote sensing data?’. Global open source data for evapotranspiration (ET), precipitation (P), areas equipped for irrigation and storage change are combined with outputs from the Aral Sea Basin management model (ASBmm). These are used to determine the actual irrigated areas, check the model data with water balances and calculate consumed fractions. The results show a trend of increasing CF with increasing irrigated area and larger CFs in downstream areas compared to upstream areas. It shows a big difference (40%) without and with complete reuse of upstream drainage water in downstream irrigated areas. These trends conform to the expectations. The second part of this study investigates why basin analysis is not structurally included in World Bank financed irrigation projects. Knowledge exchange is crucial for innovation and adopting new paradigms (Filieri et al., 2014; Walter et al., 2007). This is researched with the research question: «\’To what extent can a social capital analysis of knowledge exchange between academic hydrologists, World Bank staff and World Bank water and irrigation consultants aid the incorporation of the basin scale perspective on water consumption in World Bank financed irrigation projects?’. The social capital perspective provides a systematic way to look at the dimensions of knowledge exchange in a social network (Adler and Kwon, 2002). The results from semi-structured interviews are compared to the conceptual framework which was deduced from a systematic literature review.One of the main obstacles in knowledge exchange and including basin analysis in World Bank financed irrigation projects is lack of time and resources. Proper basin analysis is not conducted because it is not a formal requirement. Additional issues are: ambiguity of the term efficiency, spatial distance between people and differences goals and perspectives within the Bank and between the Bank and client countries. Client countries are leading in project development and the moment the Bank has a background role. The application of basin scale analysis in World Bank financed irrigation projects should be formalized. This does not mean that investments in irrigation efficiency must stop, it means that a basin analysis is necessary to make an informed decision about that investment. Water ManagementApplied Sciences | Science Communicatio
Simulating sprouting angiogenesis: Using a new 3D substrate dependent cell-based model
No full textAngiogenesis1 is the biological mechanism by which new blood vessels sprout from existing ones. It differs from vasculogenesis, which is the de novo growth of the primary vascular network from initially dispersed endothelial cells (ECs). Vasculogenesis is predominant in embryonic tissue whilst new vasculature in the adult body arises mostly from angiogenesis. ECs, lining the inside of blood vessels, react to different angiogenic stimuli and inhibitors. Among the stimuli is the vascular endothelial growth factor (VEGF) which is up-regulated in tissue where the vascular structure is damaged or insufficiently developed to meet oxygen demand. The identification of the processes involved in angiogenesis is quite recent and has stirred increased interest in therapeutic and clinical applications according to Carmeliet et al. [1]. One can think of tissue repair in wound beds, inhibition of growth of tumorous tissue or vascular reform during the female reproductive cycle. Rossiter et al. [2] showed that VEGF induced angiogenesis is crucial for wound healing in an experiment where wounds were inflicted upon normal and VEGF-deficient mice. New vasculature ensures supply of oxygen and lymphocytes and disposal of carbon dioxide and lactates, accelerating wound healing and tissue reconstruction. The increased creation of new vasculature around tumorous tissue is believed to follow the same process and inhibiting angiogenesis is therefore an important topic in clinical studies on cancer treatment. Biochemical laboratory experiments can be hard, time consuming, expensive or unethical. Computational models can be used to provide an easy, quick and cheap way to get insights that would otherwise require laboratory experiments. The understanding of biological processes needs quantification and in this sense mathematical formulation of the relations involved becomes useful. Their mathematical interpretation and experimental verification is an iterative process resulting in better understanding of the process itself. Computer simulation will never make laboratory experiments obsolete, but it can provide guidance in targeting viable hypotheses before conducting in vitro or in vivo experiments. Mathematical modeling of biological cellular processes dates back to the simulation by Glazier and Graner in 1992. They describe natural sorting behavior of different cell types [3] and different re-arrangement patterns driven by the differential adhesion hypothesis [4]. This hypothesis states that cells of different types have specific potential energies upon adhesion, driving sorting behavior. In these simulations, the cellular Potts model2 (CPM) is used. A CPM for vasculogenesis based on this work was made byMerks et al. [5, 6] in which a layer of partial differential equations (PDEs) models the chemoattractants. Later, Merks added Vascular Endothelial cadherin (VE-cadherin) caused contact-inhibited chemotaxis to simulate angiogenic-like sprout formation [7]. From an initial clump of ECs in the model sprouting behavior appears. Merks postulates that both vasculogenesis and angiogenesis must be driven by the same principles. To produce these results, a generic library called the Tissue Simulation Toolkit (TST) was written in C++ starting from 2004 modeling the CPM described by Glazier et al. [4] in a generic way. Merks [7] extensively describes the advantages of a cell based approach over a continuum approach that is widely used in mathematical biology. Although his CPM is a nice method that increases insight in the angiogenic process, it is computationally heavy, limiting the scalability of the tractable problem domain. Vermolen and Gefen [8] described tissue behavior using a semi-stochastic cell-based formalism to model the migration of cells in colonies in the context of wound healing, tumor growth, bone ingrowth and contraction formation. Movement of cells is assumed to be the result of a strain energy density working as a mechanical stimulus. Like the CPM, the model tracks displacement and viability of individual cells. The aim of this study is to adapt this semi-stochastic cell-based formalism to describe angiogenesis, hence connecting this modeling approach to the subject ofMerks’ work. The need for such a model is clearly stated in the discussion of Vermolen’s work [9]. Thanks to the computational less heavy character in comparison with the CPM, we hope to be able to simulate larger areas to get a better glance at large scale behavior whilst still being able to benefit from the cell-based character of the model. We also improve the biochemical model for the degrading of the substrate by the cells and formulate all relevant parameters based on local properties. The challenge is to translate the advantages of Merks’ CPM, like cell shape specific behavior, tracking of elongation patterns and cell-cell contact behavior, to this new formalism without compromising the computational simplicity. To verify our simulation results with biochemical experiments, this study is performed in collaboration with the Dermatology Department of the VU Medical Center. This department does in vitro laboratory research on many processes that occur in the skin, for example the role of endothelial cells during skin wound healing. The first aim of this research is tomimic their in vitro angiogenesis sprouting assay using our computational model, simulating the response to different chemical stimuli like VEGF. Formulating a way to visually and numerically compare the laboratory work to the simulated results is key to making the model applicable in practice.Numerical AnalysisApplied mathematicsElectrical Engineering, Mathematics and Computer Scienc
Modelling the influence of physical properties of extracellular polymeric substances in aerobic granule morphology
No full textThis thesis examines the influence of physical properties of structural EPS on granule morphology. Two types of structural EPS are found to be important. These types of structural EPS are: surface bound EPS and hydrogel forming EPS matrix. VirtualLeaf is used to model granules which contain only binding surface bound EPS. The TST model is used to find the influence of both structural EPS components. In VirtualLeaf compact granules are formed with slight bulging features, similar to granules found in literature. The TST shows that binding surface binding EPS increase the compactness of granules. Furthermore it is shown that porosity of the EPS matrix also determines compactness and maximum size of granules. The strength and measure of the EPS matrix is shown to influence granule stability.Environmental Biotechnolog
Support for families at home during childhood cancer treatment: a pilot study with Mr.V the Spaceman, a family-based activities tool
No full textPurpose: It is important to support families in dealing with the distress that comes along with the diagnosis and treatment of childhood cancer. Therefore, we developed a playful tool that families can use at home to support their family functioning and safeguard their normal family life. We pilot tested this new tool called Mr.V and describe how families used and evaluated the tool, and how it could be further improved. Methods: Mr.V is an interactive dispenser that looks like a spaceman and proposes family activities. These activities are suggested by family members themselves and dispensed by the machine at unexpected moments. Mr.V produced data on how it was used, and a questionnaire and a semi-structured interview were used to evaluate the experiences of families and the potential of this tool. Results: Ten families with a child with cancer between 5 and 9 years old (Mage = 6.7 years) who were in active treatment (mixed diagnoses) participated (n = 47; npatients = 10, nsiblings = 9, nparents = 16). All families used Mr.V for multiple days and were very satisfied with the tool regarding its acceptability, feasibility, and potential effectiveness. They also had suggestions on how the tool could be further improved. Conclusion: Mr.V is an acceptable and feasible tool that can be implemented by families independently at home, regardless of their level of need for support. Mr.V promoted family activities and therefore has the potential to support family functioning and normal family life at home. Future research should further investigate the effectiveness of this tool.Design AestheticsHuman Information Communication Desig
Interactive Education on Sleep Hygiene with a Social Robot at a Pediatric Oncology Outpatient Clinic: Feasibility, Experiences, and Preliminary Effectiveness
No full textObjectives: Children with cancer often experience sleep problems, which are associated with many negative physical and psychological health outcomes, as well as with a lower quality of life. Therefore, interventions are strongly required to improve sleep in this population. We evaluated interactive education with respect to sleep hygiene with a social robot at a pediatric oncology outpatient clinic regarding the feasibility, experiences, and preliminary effectiveness. Methods: Researchers approached children (8 to 12 years old) who were receiving anticancer treatment and who were visiting the outpatient clinic with their parents during the two-week study period. The researchers completed observation forms regarding feasibility, and parents completed the Children’s Sleep Hygiene Scale before and two weeks after the educational regimen. The experiences of children and parents were evaluated in semi-structured interviews. We analyzed open answers by labeling each answer with a topic reflecting the content and collapsed these topics into categories. We used descriptive statistics to describe the feasibility and experiences, and a dependent-samples t-test to evaluate the preliminary effectiveness. Results: Twenty-eight families participated (58% response rate) and all interactions with the robot were completed. The children and parents reported that they learned something new (75% and 50%, respectively), that they wanted to learn from the robot more often (83% and 75%, respectively), and that they applied the sleeping tips from the robot afterwards at home (54%). Regarding the preliminary effectiveness, children showed a statistically significant improvement in their sleep hygiene (p = 0.047, d = 0.39). Conclusions: Providing an educational regimen on sleep hygiene in a novel, interactive way by using a social robot at the outpatient clinic seemed feasible, and the children and parents mostly exhibited positive reactions. We found preliminary evidence that the sleep hygiene of children with cancer improved.Interactive Intelligenc
An Experimental Education Project for Consultations of Older Adults during the Pandemic and Healthcare Lockdown
No full textObjective: To develop a mentor-supervised, interprofessional, geriatric telemedicine experiential education project in response to the COVID-19 pandemic. Method: Medical and pharmacy students collaborated via remote consultations to address the coexistence of multimorbidity and polypharmacy in geriatric patients. In-depth interviews of students and patients as well as Likert scale-based telephonic survey were performed for a comprehensive evaluation of the project’s significance. Results: To date, 49 consultations have been conducted. Remote consultations performed by medical and pharmacy students working collaboratively were beneficial for both students, participants. Conclusions and Practice Implications: This experimental education project provided students with authentic challenges while simultaneously delivering care to the older adults who are susceptible to disruption of care associated with the pandemic. Further development and expanded implementation of such approaches may be a post-pandemic practice to provide more accessible care for senior patients while incorporating interprofessional education
