MPC for MPC: Secure Computation on a Massively Parallel Computing Architecture

Massively Parallel Computation (MPC) is a model of computation widely believed to best capture realistic parallel computing architectures such as large-scale MapReduce and Hadoop clusters. Motivated by the fact that many data analytics tasks performed on these platforms involve sensitive user data, we initiate the theoretical exploration of how to leverage MPC architectures to enable efficient, privacy-preserving computation over massive data. Clearly if a computation task does not lend itself to an efficient implementation on MPC even without security, then we cannot hope to compute it efficiently on MPC with security. We show, on the other hand, that any task that can be efficiently computed on MPC can also be securely computed with comparable efficiency. Specifically, we show the following results: - any MPC algorithm can be compiled to a communication-oblivious counterpart while asymptotically preserving its round and space complexity, where communication-obliviousness ensures that any network intermediary observing the communication patterns learn no information about the secret inputs; - assuming the existence of Fully Homomorphic Encryption with a suitable notion of compactness and other standard cryptographic assumptions, any MPC algorithm can be compiled to a secure counterpart that defends against an adversary who controls not only intermediate network routers but additionally up to 1/3 - ? fraction of machines (for an arbitrarily small constant ?) - moreover, this compilation preserves the round complexity tightly, and preserves the space complexity upto a multiplicative security parameter related blowup. As an initial exploration of this important direction, our work suggests new definitions and proposes novel protocols that blend algorithmic and cryptographic techniques

The effects of goal orientations on knowledge management system usage, knowledge sourcing and learning outcome

This research investigates individual differences in the context of knowledge management system (KMS) usage, knowledge sourcing and learning outcome. Individual differences are measured for mastery, performance and avoidance goal orientations. Individuals with high mastery goal orientations prefer to master and develop new skills and knowledge. Those with high performance goal orientations prefer to compare their performances with others. Lastly, those with high avoidance goal orientations prefer to avoid a new task if they feel incompetent. User posting and reading activities in a KMS are examined over a 3- month period. Consistent with goal orientation theory, the results show that mastery goal orientation has an effect on reading, knowledge sourcing and learning outcome. In contrast, performance goal orientation has an effect only on posting, but not on reading. To a lesser degree than mastery goal orientation, avoidance goal orientation has an effect on reading, but not posting. These findings have important implications for both knowledge management researchers and practitioners

Especies de Galacantha y Munidopsis (Crustacea: Decapoda: Anomura: Galatheidae) de las aguas profundas frente a Taiwan, con la descripción de dos nuevas especies

One species of the genus Galacantha A. Milne-Edwards, 1880, and 20 species of Munidopsis Whiteaves, 1874, including two new species, are reported from the deep-waters off Taiwan. Munidopsis echinata n. sp. closely resembles M. colombiana Pequegnat and Pequegnat, 1971 from the Caribbean Sea, but differs in lacking an antennal spine on the carapace and having a much longer antennal peduncle. Munidopsis tuberosa n. sp. appears close to M. granosicorium Williams and Baba, 1990 from the northeast Pacific, but the configuration of the carapace and rostrum separates these two species. Altogether 31 species of Munidopsis are now recorded from Taiwan, indicating a particularly rich deep-sea fauna of the island.Una especie del género Galacantha A. Milne-Edwards, 1880, y 20 especies de Munidopsis Whiteaves, 1874, incluyendo dos especies nuevas, han sido reportadas en aguas profundas de Taiwan. Munidopsis echinata n. sp., se parece mucho a M. colombiana Pequegnat y Pequegnat, 1971 del mar del Caribe, pero se diferencia por faltarle una espina antenal en el caparazón y por tener un pedunculo antennal mucho más largo. Munidopsis tuberosa n. sp., parece próxima a M. granosicorium Williams y Baba, 1990 del Pacífico noreste, pero la configuración de su caparazón y rostro separa estas dos especies. En conjunto se han reportado 31 especies de Munidopsis en Taiwan, indicando una fauna de profundidad particularmente rica en la isla

Charmonium Absorption in the Meson-exchange Model

We review the meson-exchange model for charmonium absorption by hadrons. This includes the construction of the interaction Lagrangians, the determination of the coupling constants, the introduction of form factors, and the predicted cross sections for $J/\psi$ absorption by both mesons and nucleons. We further discuss the effects due to anomalous parity interactions, uncertainties in form factors, constraints from chiral symmetry, and the change of charmed meson mass in medium on the cross sections for charmonium absorption in hadronic matter.Comment: 10 pages, 2 figures. Talk given at Quark Matter 2002 (QM 2002), Nantes, France, 18-24 July 2002. To appear in the proceedings (Nucl. Phys. A

Regulation of Skp2 Expression and Activity and Its Role in Cancer Progression

The regulation of cell cycle entry is critical for cell proliferation and tumorigenesis. One of the key players regulating cell cycle progression is the F-box protein Skp2. Skp2 forms a SCF complex with Skp1, Cul-1, and Rbx1 to constitute E3 ligase through its F-box domain. Skp2 protein levels are regulated during the cell cycle, and recent studies reveal that Skp2 stability, subcellular localization, and activity are regulated by its phosphorylation. Overexpression of Skp2 is associated with a variety of human cancers, indicating that Skp2 may contribute to the development of human cancers. The notion is supported by various genetic mouse models that demonstrate an oncogenic activity of Skp2 and its requirement in cancer progression, suggesting that Skp2 may be a novel and attractive therapeutic target for cancers