Lightweight Security for Network Coding

Under the emerging network coding paradigm, intermediate nodes in the network are allowed not only to store and forward packets but also to process and mix different data flows. We propose a low-complexity cryptographic scheme that exploits the inherent security provided by random linear network coding and offers the advantage of reduced overhead in comparison to traditional end-to-end encryption of the entire data. Confidentiality is achieved by protecting (or "locking") the source coefficients required to decode the encoded data, without preventing intermediate nodes from running their standard network coding operations. Our scheme can be easily combined with existing techniques that counter active attacks.Comment: Proc. of the IEEE International Conference on Communications (ICC 2008), Beijing, China, May 200

Constraints on Physical Properties of z~6 Galaxies Using Cosmological Hydrodynamic Simulations

We conduct a detailed comparison of broad-band spectral energy distributions of six z >= 5.5 galaxies against galaxies drawn from cosmological hydrodynamic simulations. We employ a new tool called SPOC, which constrains the physical properties of observed galaxies through a Bayesian likelihood comparison with model galaxies. For five out of six observed z>=5.5 objects, our simulated galaxies match the observations at least as well as simple star formation histories such as tau-models, with similar favored values obtained for the intrinsic physical parameters such as stellar mass and star formation rate, but with substantially smaller uncertainties. Our results are broadly insensitive to simulation choices for galactic outflows and dust reddening. Hence the existence of early galaxies as observed is broadly consistent with current hierarchical structure formation models. However, one of the six objects has photometry that is best fit by a bursty SFH unlike anything produced in our simulations, driven primarily by a high K-band flux. These findings illustrate how SPOC provides a robust tool for optimally utilizing hydrodynamic simulations (or any model that predicts galaxy SFHs) to constrain the physical properties of individual galaxies having only photometric data, as well as identify objects that challenge current models. (abridged)Comment: 22 pages, 11 figures, accepted by MNRAS. Added discussions of dust, numerical resolution; clarified conclusion

Cross-dimensional Weighting for Aggregated Deep Convolutional Features

We propose a simple and straightforward way of creating powerful image representations via cross-dimensional weighting and aggregation of deep convolutional neural network layer outputs. We first present a generalized framework that encompasses a broad family of approaches and includes cross-dimensional pooling and weighting steps. We then propose specific non-parametric schemes for both spatial- and channel-wise weighting that boost the effect of highly active spatial responses and at the same time regulate burstiness effects. We experiment on different public datasets for image search and show that our approach outperforms the current state-of-the-art for approaches based on pre-trained networks. We also provide an easy-to-use, open source implementation that reproduces our results.Comment: Accepted for publications at the 4th Workshop on Web-scale Vision and Social Media (VSM), ECCV 201

Hitchhiker capabilities

A carrier system has been developed for economical and quick response flight of small attached payloads on the space shuttle. Hitchhiker can accommodate up to 750 lb of customer payloads in canisters or mounted to an exposed side-mount plate, or up to 1200 lb mounted on a cross-bay structure. The carrier connects to the orbiter's electrical systems and provides up to six customers with standard electrical services including power, real time telemetry and commands. A transparent data and command system concept is employed to allow the customer to easily use his own ground support equipment and personnel to control his payload during integration and flight operations. A general description of the Hitchhiker program and the Shuttle Payload of Opportunity Carrier (SPOC) is given and future enhancements are outlined