Live Demonstration:Neuromorphic Sensory Integration for Combining Sound Source Localization and Collision Avoidance

The brain is able to solve complex tasks in real time by combining different sensory cues with previously acquired knowledge. Inspired by the brain, we designed a neuromorphic demonstrator which combines auditory and visual input to find an obstacle free direction closest to the sound source. The system consists of two event-based sensors (the eDVS for vision and the NAS for audition) mounted onto a pan-tilt unit and a spiking neural network implemented on the SpiNNaker platform. By combining the different sensory information, the demonstrator is able to point at a sound source direction while avoiding obstacles in real time

Contextual and Granular Policy Enforcement in Database-backed Applications

Database-backed applications rely on inlined policy checks to process users' private and confidential data in a policy-compliant manner as traditional database access control mechanisms cannot enforce complex policies. However, application bugs due to missed checks are common in such applications, which result in data breaches. While separating policy from code is a natural solution, many data protection policies specify restrictions based on the context in which data is accessed and how the data is used. Enforcing these restrictions automatically presents significant challenges, as the information needed to determine context requires a tight coupling between policy enforcement and an application's implementation. We present Estrela, a framework for enforcing contextual and granular data access policies. Working from the observation that API endpoints can be associated with salient contextual information in most database-backed applications, Estrela allows developers to specify API-specific restrictions on data access and use. Estrela provides a clean separation between policy specification and the application's implementation, which facilitates easier auditing and maintenance of policies. Policies in Estrela consist of pre-evaluation and post-evaluation conditions, which provide the means to modulate database access before a query is issued, and to impose finer-grained constraints on information release after the evaluation of query, respectively. We build a prototype of Estrela and apply it to retrofit several real world applications (from 1000-80k LOC) to enforce different contextual policies. Our evaluation shows that Estrela can enforce policies with minimal overheads

1.6 {\AA} structure of an NAD+-dependent quinate dehydrogenase from Corynebacterium glutamicum

To date, three different functional classes of bacterial shikimate/quinate dehydrogenases have been identified and are referred to as AroE, SDH-L and YdiB. The enzyme AroE and the catalytically much slower SDH-L clearly prefer NADP+/NADPH as the cosubstrate and are specific for (dehydro-)shikimate, whereas in YdiB the differences in affinity for NADP+/NADPH versus NAD+/NADH as well as for (dehydro-)shikimate versus (dehydro-)quinate are marginal. These three subclasses have a similar three-dimensional fold and hence all belong to the same structural class of proteins. In this paper, the crystal structure of an enzyme from Corynebacterium glutamicum is presented that clearly prefers NAD+ as a cosubstrate and that demonstrates a higher catalytic efficiency for quinate rather than shikimate. While the kinetic constants for this enzyme clearly differ from those reported for AroE, SDH-L and YdiB, the three-dimensional structure of this protein is similar to members of these three subclasses. Thus, the enzyme described here belongs to a new functional class of the shikimate/quinate dehydrogenase family. The different substrate and cosubstrate specificities of this enzyme relative to all other known bacterial shikimate/quinate dehydrogenases are discussed by means of analyzing the crystal structure and derived models. It is proposed that in contrast to shikimate, quinate forms a hydrogen bond to the NAD+. In addition, it is suggested that the hydroxyl group of a conserved active-site threonine hydrogen bonds to quinate more effectively than to shikimate. Also, the hydroxyl group of a conserved tyrosine approaches the carboxylate group of quinate more closely than it does the carboxylate group of shikimate. Taken together, these factors most likely lead to a lower Michaelis constant and therefore to a higher catalytic efficiency for quinate. The active site of the dehydrogenase reported here is larger than those of other known shikimate/quinate dehydrogenases, which may explain why quinate is easily accommodated within the catalytic cleft

Automatic annotation of confidential data in java code

The problem of confidential information leak can be addressed by using automatic tools that take a set of annotated inputs (the source) and track their flow to public sinks. Unfortunately, manually annotating the code with labels specifying the secret sources is one of the main obstacles in the adoption of such trackers. In this work, we present an approach for the automatic generation of labels for confidential data in Java programs. Our solution is based on a graph-based representation of Java methods: starting from a minimal set of known API calls, it propagates the labels both intra- and inter-procedurally until a fix-point is reached. In our evaluation, we encode our synthesis and propagation algorithm in Datalog and assess the accuracy of our technique on seven previously annotated internal code bases, where we can reconstruct 75% of the pre-existing manual annotations. In addition to this single data point, we also perform an assessment using samples from the SecuriBench-micro benchmark, and we provide additional sample programs that demonstrate the capabilities and the limitations of our approach

Note on a bubble model for excess electrons in liquid hydrocarbons

It is shown that a simple bubble model for electrons in liquid hexane that has been suggested recently does not satisfy the necessary stability criteria if the macroscopic properties of liquid hexane are used. Stability can be achieved, however, by assuming a higher dielectric constant ϵ than the macroscopic value. For hexane and some other hydrocarbons we have varied ϵ until the stable bubble model yields the experimentally determined activation energies of the mobility. The resulting values of ϵ turn out to be nearly the same for all liquids investigated

Note on the vortex density in rotating helium II

Computer calculations show that there exist no large stable deviations from the homogeneous vortex density in an annulus or cylinder; the solutions of Masson and Tien are unstable

Positive ion mobility in normal and superfluid 3He

The mobility of positive ions has been measured in the normal and superfluid phases of 3He at several pressures. Below 100 mK the normal phase mobility increases logarithmically with decreasing temperature down to the superfluid transition temperature T c; it shows an anomalous jump near 100 mK. At low temperatures the drift velocity is nonlinear for electric fields exceeding 30 V/cm. In the superfluid the mobility, normalized to its value at T c, is much less than for negative ions. We have also observed the anisotropic mobility in the A phase and the Landau critical velocity for pair-breaking in both superfluid phases