Provably-secure symmetric private information retrieval with quantum cryptography

Private information retrieval (PIR) is a database query protocol that provides user privacy, in that the user can learn a particular entry of the database of his interest but his query would be hidden from the data centre. Symmetric private information retrieval (SPIR) takes PIR further by additionally offering database privacy, where the user cannot learn any additional entries of the database. Unconditionally secure SPIR solutions with multiple databases are known classically, but are unrealistic because they require long shared secret keys between the parties for secure communication and shared randomness in the protocol. Here, we propose using quantum key distribution (QKD) instead for a practical implementation, which can realise both the secure communication and shared randomness requirements. We prove that QKD maintains the security of the SPIR protocol and that it is also secure against any external eavesdropper. We also show how such a classical-quantum system could be implemented practically, using the example of a two-database SPIR protocol with keys generated by measurement device-independent QKD. Through key rate calculations, we show that such an implementation is feasible at the metropolitan level with current QKD technology.Comment: 19 page

Inverse regression for longitudinal data

Sliced inverse regression (Duan and Li [Ann. Statist. 19 (1991) 505-530], Li [J. Amer. Statist. Assoc. 86 (1991) 316-342]) is an appealing dimension reduction method for regression models with multivariate covariates. It has been extended by Ferr\'{e} and Yao [Statistics 37 (2003) 475-488, Statist. Sinica 15 (2005) 665-683] and Hsing and Ren [Ann. Statist. 37 (2009) 726-755] to functional covariates where the whole trajectories of random functional covariates are completely observed. The focus of this paper is to develop sliced inverse regression for intermittently and sparsely measured longitudinal covariates. We develop asymptotic theory for the new procedure and show, under some regularity conditions, that the estimated directions attain the optimal rate of convergence. Simulation studies and data analysis are also provided to demonstrate the performance of our method.Comment: Published in at http://dx.doi.org/10.1214/13-AOS1193 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org). With Correction

Implications of new data in charmless B decays

Based on the latest experimental data of $B \to \pi\pi$ and $\pi K$ modes, a model-independent analytical analysis is presented. The CP-averaged branching ratio difference $\Delta R = R_c - R_n$ in $B\to \pi K$ decays with $R_c = 2Br(\pi^0K^-)/Br(\pi^-\bar{K}^0)$ and $R_n =Br(\pi^+K^-)/2Br(\pi^0\bar{K}^0)$ is reduced though it remains larger than the prediction from the standard model(SM) as both measured $R_n$ and $R_c$ are enhanced, which indicates that a room for new physics becomes smaller. The present data of $\pi\pi$ decay reduce the ratio $|C/T|$ from the previous value of $|C/T|\simeq 0.8$ to $|C/T| \simeq 0.65$, which is still larger than the theoretical estimations based on QCD factorization and pQCD. Within SM and flavor SU(3) symmetry, the current $\pi K$ data also diminish the ratio $|C'/T'|$ from the previous value $|C'/T'| \simeq 2$ to $|C'/T'| \simeq 1.16$ with a large strong phase $\delta_{C'} \simeq -2.65$, while its value remains much larger than the one extracted from the $\pi \pi$ modes. The direct CP violation $A_{CP}(\pi^0\bar{K}^0)$ is predicted to be $A_{CP}(\pi^0\bar{K}^0) = -0.15\pm0.03$, which is consistent with the present data. Two kinds of new effects in both strong and weak phases of the electroweak penguin diagram are considered. It is found that both cases can reduce the ratio to $|C'/T'| = 0.40\sim 0.80$ and lead to roughly the same predictions for CP violation in $\pi^0 K^0$.Comment: 13 pages, 4 figure

Misfit of rigid tools and interferometer subapertures on off-axis aspheric mirror segments

Rigid tools can confer advantages at certain stages of manufacturing off-axis mirror segments, but the misfit due to surface asphericity and asymmetry poses constraints on their application. Types of misfit are classified and, using least squares, the best-fit tool forms with different distances from the pole of the parent asphere are calculated. The outer mirror segment for the European extremely large telescope is taken as a case-study, assuming a rigid tool size of 150 mm. A simple independent approximation validates the calculation. A close parallel is wavefront misfit in subaperture interferometry, which is also considered

ICPR2017 – The Fourth International Conference on Practice Research: overview

This paper reports issues arising from the Fourth International Conference on Practice Research, held in Hong Kong in May 2017. The issues were identified by specially convened group of conference participants, and include the need to develop a better language to describe practice research in terms that make sense to practitioners, improved support for practitioners to conduct research, recognising the different drivers for practice research in different countries, and enhancing practitioners' coordinating and leadership roles

Cross-Dataset Person Re-Identification via Unsupervised Pose Disentanglement and Adaptation

Person re-identification (re-ID) aims at recognizing the same person from images taken across different cameras. To address this challenging task, existing re-ID models typically rely on a large amount of labeled training data, which is not practical for real-world applications. To alleviate this limitation, researchers now targets at cross-dataset re-ID which focuses on generalizing the discriminative ability to the unlabeled target domain when given a labeled source domain dataset. To achieve this goal, our proposed Pose Disentanglement and Adaptation Network (PDA-Net) aims at learning deep image representation with pose and domain information properly disentangled. With the learned cross-domain pose invariant feature space, our proposed PDA-Net is able to perform pose disentanglement across domains without supervision in identities, and the resulting features can be applied to cross-dataset re-ID. Both of our qualitative and quantitative results on two benchmark datasets confirm the effectiveness of our approach and its superiority over the state-of-the-art cross-dataset Re-ID approaches.Comment: Accepted to ICCV 201