Estimating Body Segment Orientation by Applying Inertial and Magnetic Sensing Near Ferromagnetic Materials

Inertial and magnetic sensors are very suitable for ambulatory monitoring of human posture and movements. However, ferromagnetic materials near the sensor disturb the local magnetic field and, therefore, the orientation estimation. A Kalman-based fusion algorithm was used to obtain dynamic orientations and to minimize the effect of magnetic disturbances. This paper compares the orientation output of the sensor fusion using three-dimensional inertial and magnetic sensors against a laboratory bound opto-kinetic system (Vicon) in a simulated work environment. With the tested methods, the difference between the optical reference system and the output of the algorithm was 2.6deg root mean square (rms) when no metal was near the sensor module. Near a large metal object instant errors up to 50deg were measured when no compensation was applied. Using a magnetic disturbance model, the error reduced significantly to 3.6deg rms

Compensation of Magnetic Disturbances Improves Inertial and Magnetic Sensing of Human Body Segment Orientation

This paper describes a complementary Kalman filter design to estimate orientation of human body segments by fusing gyroscope, accelerometer, and magnetometer signals from miniature sensors. Ferromagnetic materials or other magnetic fields near the sensor module disturb the local earth magnetic field and, therefore, the orientation estimation, which impedes many (ambulatory) applications. In the filter, the gyroscope bias error, orientation error, and magnetic disturbance error are estimated. The filter was tested under quasi-static and dynamic conditions with ferromagnetic materials close to the sensor module. The quasi-static experiments implied static positions and rotations around the three axes. In the dynamic experiments, three-dimensional rotations were performed near a metal tool case. The orientation estimated by the filter was compared with the orientation obtained with an optical reference system Vicon. Results show accurate and drift-free orientation estimates. The compensation results in a significant difference (p<0.01) between the orientation estimates with compensation of magnetic disturbances in comparison to no compensation or only gyroscopes. The average static error was 1.4/spl deg/ (standard deviation 0.4) in the magnetically disturbed experiments. The dynamic error was 2.6/spl deg/ root means square

Achieving Sustainability Through Geodata: An Empirical Study of Challenges and Barriers

Master's thesis in Information systems (IS501)Research within data management is often based on the elements of the data lifecycle. Organizations and businesses are also becoming more interested in data lifecycle management to leverage their data streams, compounded by an interest in geographical attributes within the data –referred to as geodata. Geodata provides a richer basis for analysis and is increasingly important within urban planning. Furthermore, the pressure to achieve sustainability goals calls for improving the data lifecycle. The challenge remainsas to what can be improvedwithin the data lifecycle –with geodata as an important input –to achieve sustainability dimensions. Our main contribution through this study is shedding light on challenges withgeodata from an Information Systems (IS) and sustainability perspective. Additionally, the identified challenges are also feedback to data management research and the data lifecycle

Interial sensing in a hand held dynamometer

Two methods for kinematic sensing in a hand-held dynamometer using accelerometers and gyroscopes are presented. The first method integrates the angular velocity signal from the gyroscope, after calibration of gyroscope offset and joint angle from a static period immediately preceding each measurement. The second method estimates tangential and radial accelerations, enabling the estimation of the gravity components in the accelerometer signals under dynamic conditions, and thus angle reconstruction. The second method appeared to perform best in preliminary test

Capacity Building in Earth Observation: from Outcomes to Impact and Sustainability : abstract + powerpoint

Spatial solutions play an increasingly important role in meeting many of humankind’s complex challenges, such as climate change, population growth, and related claims for sufficient and secure food, water, energy, health, land and housing provision. Earth observations and geospatial technology are rapidly changing society everywhere − mobile, sensor and internet revolutions are touching Africa and Asia equally forcefully. Entrepreneurship and innovation are new aspects in capacity development activities. Many capacity building efforts focus on individuals while sustainable impact requires focus on organizational change and supranational coordination. Over the past several decades, many regional centers have been established for capacity building in Earth observation in developing countries and emerging economies. ITC of the University of Twente is an international knowledge hub in geospatial sciences, with an emphasis on collaborative educational and research activities in geo-information science and Earth observation and participation of students from around the world. SERVIR is a partnership of NASA, USAID, and leading regional technical organizations that develops innovative geospatial solutions to improve livelihoods and foster self-reliance across a global network in Asia, Africa, and the Americas. In this presentation, ITC and SERVIR will provide examples of and lessons learned from our activities and networks to strengthen the capacity and use of Earth observations in the developing world

Characterization of Lysozyme Stability in the Presence of lonic Liquids

Hen egg white lysozyme (Lyz) has been a well studied model system in biophysical investigations for decades. The protein is a small, primarily helical, highly soluble protein that is both commercially available and easily accessible. lonic liquids (ILs), often referred to as room-temperature ionic liquids or molten salts, have garnered great interest in the last 15-20 years as potential components of electrochemical devices or applications. More recently, the biocompatibility of these molecules has developed an increased interest in the field, especially considering that some IL species can stabilize biomolecular structures while other ILs strongly destabilize 3D structures. In this study, we used fluorescence spectroscopy to characterize the unfolding of lysozyme and the impact imidazolium-based ILs had on this process. The ILs 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium chloride were first evaluated for their impacts alone, and subsequently on their ability to destabilize the lysozyme when denatured with Guanidinium HCl. Consistent with previous findings, the alkyl chain length had an impact on the destabilization potential of the ILs. Subsequent studies on the denaturation process in using thermal-induced denaturation, as well as quenching studies throughout the process, were also investigated to gain insight into the denaturation process. Overall, longer alkyl chain length ILs more strongly destabilize the lysozyme 3D structure

Fatty acid 16:4(n-3) stimulates a GPR120-induced signaling cascade in splenic macrophages to promote chemotherapy resistance

Although chemotherapy is designed to eradicate tumor cells, it also has significant effects on normal tissues. The platinum-induced fatty acid 16:4(n-3) (hexadeca-4,7,10,13-tetraenoic acid) induces systemic resistance to a broad range of DNA-damaging chemotherapeutics. We show that 16:4(n-3) exerts its effect by activating splenic F4/80+/CD11blow macrophages, which results in production of chemoprotective lysophosphatidylcholines (LPCs). Pharmacologic studies, together with analysis of expression patterns, identified GPR120 on F4/80+/CD11blow macrophages as the relevant receptor for 16:4(n-3). Studies that used splenocytes from GPR120-deficient mice have confirmed this conclusion. Activation of the 16:4(n-3)-GPR120 axis led to enhanced cPLA2 activity in these splenic macrophages and secretion of the resistance-inducing lipid mediator, lysophosphatidylcholine(24:1). These studies identify a novel and unexpected function for GPR120 and suggest that antagonists of this receptor might be effective agents to limit development of chemotherapy resistance.—Houthuijzen, J. M., Oosterom, I., Hudson, B. D., Hirasawa, A., Daenen, L. G. M., McLean, C. M., Hansen, S. V. F., van Jaarsveld, M. T. M., Peeper, D. S., Jafari Sadatmand, S., Roodhart, J. M. L., van de Lest, C. H. A., Ulven, T., Ishihara, K., Milligan, G., Voest, E. E. Fatty acid 16:4(n-3) stimulates a GPR120-induced signaling cascade in splenic macrophages to promote chemotherapy resistance

Effects of intensity on emotion regulation strategy preferences are emotion-specific

Adaptive emotion regulation is characterized by the ability to flexibly select and switch between different strategies, depending on individual and contextual factors. Previous studies have shown that people prefer disengagement strategies to regulate more intense emotions, while they prefer engagement strategies to regulate less intense emotions. In this study, we investigated whether – in addition to the intensity of emotions – the discrete emotion type (disgust versus fear) also affects emotion regulation strategy preferences. A total of 401 students from three different universities completed an emotion regulation choice task in which they could choose between distraction and reappraisal to regulate their emotions in response to viewing high versus low intensity disgust- and fear-evoking pictures. We found that strategy choices did indeed depend on the nature of specific emotions, with distraction being preferred for regulating disgust, and reappraisal being preferred for regulating fear. Crucially, the nature of the emotion also qualified the previously reported effect of emotion intensity on strategy choice: Only for disgust- but not for fear-evoking pictures did participants show an increased preference for distraction over reappraisal with increased emotion intensity. Our results thus show that the effects of emotional intensity on emotion regulation strategy choice are emotion-specific and indicate that factors affecting emotion regulation strategy choice interact with each other

Conductance fluctuations in diffusive rings: Berry phase effects and criteria for adiabaticity

We study Berry phase effects on conductance properties of diffusive mesoscopic conductors, which are caused by an electron spin moving through an orientationally inhomogeneous magnetic field. Extending previous work, we start with an exact, i.e. not assuming adiabaticity, calculation of the universal conductance fluctuations in a diffusive ring within the weak localization regime, based on a differential equation which we derive for the diffuson in the presence of Zeeman coupling to a magnetic field texture. We calculate the field strength required for adiabaticity and show that this strength is reduced by the diffusive motion. We demonstrate that not only the phases but also the amplitudes of the h/2e Aharonov-Bohm oscillations are strongly affected by the Berry phase. In particular, we show that these amplitudes are completely suppressed at certain magic tilt angles of the external fields, and thereby provide a useful criterion for experimental searches. We also discuss Berry phase-like effects resulting from spin-orbit interaction in diffusive conductors and derive exact formulas for both magnetoconductance and conductance fluctuations. We discuss the power spectra of the magnetoconductance and the conductance fluctuations for inhomogeneous magnetic fields and for spin-orbit interaction.Comment: 18 pages, 13 figures; minor revisions. To appear in Phys. Rev.

Bregman Voronoi Diagrams: Properties, Algorithms and Applications

The Voronoi diagram of a finite set of objects is a fundamental geometric structure that subdivides the embedding space into regions, each region consisting of the points that are closer to a given object than to the others. We may define many variants of Voronoi diagrams depending on the class of objects, the distance functions and the embedding space. In this paper, we investigate a framework for defining and building Voronoi diagrams for a broad class of distance functions called Bregman divergences. Bregman divergences include not only the traditional (squared) Euclidean distance but also various divergence measures based on entropic functions. Accordingly, Bregman Voronoi diagrams allow to define information-theoretic Voronoi diagrams in statistical parametric spaces based on the relative entropy of distributions. We define several types of Bregman diagrams, establish correspondences between those diagrams (using the Legendre transformation), and show how to compute them efficiently. We also introduce extensions of these diagrams, e.g. k-order and k-bag Bregman Voronoi diagrams, and introduce Bregman triangulations of a set of points and their connexion with Bregman Voronoi diagrams. We show that these triangulations capture many of the properties of the celebrated Delaunay triangulation. Finally, we give some applications of Bregman Voronoi diagrams which are of interest in the context of computational geometry and machine learning.Comment: Extend the proceedings abstract of SODA 2007 (46 pages, 15 figures