Mobile sensor data anonymization

Motion sensors such as accelerometers and gyroscopes measure the instant acceleration and rotation of a device, in three dimensions. Raw data streams from motion sensors embedded in portable and wearable devices may reveal private information about users without their awareness. For example, motion data might disclose the weight or gender of a user, or enable their re-identification. To address this problem, we propose an on-device transformation of sensor data to be shared for specific applications, such as monitoring selected daily activities, without revealing information that enables user identification. We formulate the anonymization problem using an information-theoretic approach and propose a new multi-objective loss function for training deep autoencoders. This loss function helps minimizing user-identity information as well as data distortion to preserve the application-specific utility. The training process regulates the encoder to disregard user-identifiable patterns and tunes the decoder to shape the output independently of users in the training set. The trained autoencoder can be deployed on a mobile or wearable device to anonymize sensor data even for users who are not included in the training dataset. Data from 24 users transformed by the proposed anonymizing autoencoder lead to a promising trade-off between utility and privacy, with an accuracy for activity recognition above 92% and an accuracy for user identification below 7

Progress Report On the Iba Shi Small Cyclotron for Cancer-therapy

A proton therapy facility using a compact, high-field nonsuperconducting cyclotron was first presented by lon Beam Applications (IBA) at the PTCOG meeting in June 1990. In December 1990, funding was secured to start the design of a prototype at IBA. In October 1991 a collaboration agreement was signed between IBA and Sumitomo Heavy Industries (SHI). The main features of this accelerator were presented elsewhere [W. Beeckman et al., Nucl. Instr. and Meth. B56/57 (1991) 1201]. The induction profile in the vicinity of the extraction radius was improved by the introduction of a magnetic shunt resulting in a completely closed gap at the median plane. The extraction system is also described. First calculations on the central region were performed using a simplified 2-D model with stacking factors in order to describe its actual 3-D geometry. Two types of isocentric gantries, namely a scanning gantry as initially proposed and a scattering gantry, are currently designed. Their status is presented in this paper

Mathematical Methods in Program Development. Springer-Verlag, 1996.

for electronic commerce. In Proc. 17th ACM Sympos. Principles of Databas