University of Twente

About: University of Twente is a education organization based out in Enschede, Overijssel, Netherlands. It is known for research contribution in the topics: Context (language use) & Population. The organization has 15890 authors who have published 39988 publications receiving 1173424 citations. The organization is also known as: Universiteit Twente.

Accuracy and Resolution of Kinect Depth Data for Indoor Mapping Applications

Abstract: Consumer-grade range cameras such as the Kinect sensor have the potential to be used in mapping applications where accuracy requirements are less strict. To realize this potential insight into the geometric quality of the data acquired by the sensor is essential. In this paper we discuss the calibration of the Kinect sensor, and provide an analysis of the accuracy and resolution of its depth data. Based on a mathematical model of depth measurement from disparity a theoretical error analysis is presented, which provides an insight into the factors influencing the accuracy of the data. Experimental results show that the random error of depth measurement increases with increasing distance to the sensor, and ranges from a few millimeters up to about 4 cm at the maximum range of the sensor. The quality of the data is also found to be influenced by the low resolution of the depth measurements.

The green, blue and grey water footprint of crops and derived crop products

Abstract: This study quantifies the green, blue and grey water footprint of global crop production in a spatially-explicit way for the period 1996–2005. The assessment improves upon earlier research by taking a high-resolution approach, estimating the water footprint of 126 crops at a 5 by 5 arc minute grid. We have used a grid-based dynamic water balance model to calculate crop water use over time, with a time step of one day. The model takes into account the daily soil water balance and climatic conditions for each grid cell. In addition, the water pollution associated with the use of nitrogen fertilizer in crop production is estimated for each grid cell. The crop evapotranspiration of additional 20 minor crops is calculated with the CROPWAT model. In addition, we have calculated the water footprint of more than two hundred derived crop products, including various flours, beverages, fibres and biofuels. We have used the water footprint assessment framework as in the guideline of the Water Footprint Network. Considering the water footprints of primary crops, we see that the global average water footprint per ton of crop increases from sugar crops (roughly 200 m3 ton−1), vegetables (300 m3 ton−1), roots and tubers (400 m3 ton−1), fruits (1000 m3 ton−1), cereals (1600 m3 ton−1), oil crops (2400 m3 ton−1) to pulses (4000 m3 ton−1). The water footprint varies, however, across different crops per crop category and per production region as well. Besides, if one considers the water footprint per kcal, the picture changes as well. When considered per ton of product, commodities with relatively large water footprints are: coffee, tea, cocoa, tobacco, spices, nuts, rubber and fibres. The analysis of water footprints of different biofuels shows that bio-ethanol has a lower water footprint (in m3 GJ−1) than biodiesel, which supports earlier analyses. The crop used matters significantly as well: the global average water footprint of bio-ethanol based on sugar beet amounts to 51 m3 GJ−1, while this is 121 m3 GJ−1 for maize. The global water footprint related to crop production in the period 1996–2005 was 7404 billion cubic meters per year (78 % green, 12 % blue, 10 % grey). A large total water footprint was calculated for wheat (1087 Gm3 yr−1), rice (992 Gm3 yr−1) and maize (770 Gm3 yr−1). Wheat and rice have the largest blue water footprints, together accounting for 45 % of the global blue water footprint. At country level, the total water footprint was largest for India (1047 Gm3 yr−1), China (967 Gm3 yr−1) and the USA (826 Gm3 yr−1). A relatively large total blue water footprint as a result of crop production is observed in the Indus river basin (117 Gm3 yr−1) and the Ganges river basin (108 Gm3 yr−1). The two basins together account for 25 % of the blue water footprint related to global crop production. Globally, rain-fed agriculture has a water footprint of 5173 Gm3 yr−1 (91 % green, 9 % grey); irrigated agriculture has a water footprint of 2230 Gm3 yr−1 (48 % green, 40 % blue, 12 % grey).

The international classification for functioning, disability and health. A challenge and a need for rheumatology.

Abstract: The rheumatologic community is in a leading position for the development of International Classification of Functioning, Disability and Health (ICF) Core Sets and the research into the validity and application of the ICF We can be proud of this achievement, but not all of us are aware of this new development What is the ICF? Rheumatologic conditions have major impact on patients Apart from symptoms such as pain, stiffness, and fatigue, patients are limited in activities and restricted in participation in society [2] When unable to continue paid work, for example, there are important consequences for the patients, their families, but also for society A major goal of the management of rheumatic diseases is to maintain or restore functioning This contributes to the well-being of the patients, their families, and other caregivers It is clear that maintaining function requires more than control of disease activity By using the ICF, which was developed by the World Health Organization (WHO), we can obtain information on all three areas that are important for global functioning: body functions and structures, activities (actions by an individual), and participation (involvement in life situations) [3] The ICF is one of the three reference classification systems that were proposed and developed by the WHO and belong to the Family of International Classifications The main aim of the classification systems is to improve integration of health information The International Classification of Diagnosis (ICD) is well known and widely applied [4] The ICF was developed from the older International Classification of Impairments, Disabilities, and Handicaps (ICIDH) and accepted in 2001 [3] It is increasingly recognized as an important classification in clinical medicine, outcome research, and healthcare organization The International Classification of Health Interventions (ICHI) is proposed as the newest member of the family, and its development has just started [1] The WHO aims to implement effectively the ICF worldwide and formulated strategic directions in which the three following are the most relevant: (1) The ICF has to become the framework to classify function, (2) easy-to-use ICF linked instruments should be developed to assess functional outcome as well as effectiveness of interventions, and (3) the level and quality of implementation of the ICF should be improved to increase quality and comparability Clin Rheumatol (2007) 26:1803–1808 DOI 101007/s10067-007-0623-0

Focusing coherent light through opaque strongly scattering media

Abstract: We report focusing of coherent light through opaque scattering materials by control of the incident wavefront. The multiply scattered light forms a focus with a brightness that is up to a factor of 1000 higher than the brightness of the normal diffuse transmission.