Privacy-Preserving Aggregation of Time-Series Data

The conference paper can be viewed at: http://www.isoc.org/isoc/conferences/ndss/11/proceedings.shtmlSession 9: PrivacyWe consider how an untrusted data aggregator can learn desired statistics over multiple participants’ data, without compromising each individual’s privacy. We propose a construction that allows a group of participants to periodically upload encrypted values to a data aggregator, such that the aggregator is able to compute the sum of all participants’ values in every time period, but is unable to learn anything else. We achieve strong privacy guarantees using two main techniques. First, we show how to utilize applied cryptographic techniques to allow the aggregator to decrypt the sum from multiple ciphertexts encrypted under different user keys. Second, we describe a distributed data randomization procedure that guarantees the differential privacy of the outcome statistic, even when a subset of participants might be compromised.published_or_final_versio

The process e+e−→π+π−π0e^+e^-\to\pi^+\pi^-\pi^0 in the energy range 2E_0=1.04 - 1.38 GeV

In the experiment with the SND detector at VEPP-2M e^+e^- collider the process $e^+e^-\to\pi^+\pi^-\pi^0$ was studied in the energy range 2E_0 from 1.04 to 1.38 GeV. A broad peak was observed with the visible mass $M_{vis}=1220\pm 20$ MeV and cross section in the maximum $\sigma_0\simeq 4$ nb. The peak can be interpreted as a $\omega$-like resonance $\omega (1200)$.Comment: 10 pages LATEX and 5 figure

The interaction of oxygen with small gold clusters

Presented in this work are the results of a quantum chemical study of oxygen adsorption on small Aun and Au−n (n=2,3) clusters. Density functional theory(DFT), second order perturbation theory (MP2), and singles and doubles coupled clustertheory with perturbative triples [CCSD(T)] methods have been used to determine the geometry and the binding energy of oxygen to Aun. The multireference character of the wave functions has been studied using the complete active space self-consistent field method. There is considerable disagreement between the oxygen binding energies provided by CCSD(T) calculations and those obtained with DFT. The disagreement is often qualitative, with DFT predicting strong bonds where CCSD(T) predicts no bonds or structures that are bonded but have energies that exceed those of the separated components. The CCSD(T) results are consistent with experimental measurements, while DFT calculations show, at best, a qualitative agreement. Finally, the lack of a regular pattern in the size and the sign of the errors [as compared to CCSD(T)] is a disappointing feature of the DFT results for the present system: it is not possible to give a simple rule for correcting the DFT predictions (e.g., a useful rule would be that DFT predicts stronger binding of O2 by about 0.3 eV). It is likely that the errors in DFT appear not because of gold, but because oxygen binding to a metal cluster is a particularly difficult problem.This work was supported by AFOSR through a DURINT grant

Cool clusters correctly correlated

This work describes the applications of ab-initio quantum chemical methods to the studies of atomic clusters. In Chapter 1 a general description of quantum chemical methods, used to solve the stationary Schrodinger equation in subsequent parts of the dissertation, is given. In Chapter 2 the adsorption of oxygen molecules on small neutral and anionic gold clusters is studied. It is shown that O2 binds better to clusters with an odd number of electrons than to clusters with an even number of electrons. DFT results are found to be in significant disagreement with high-level ab-initio CCSD(T) results. Chapter 3 describes the study of reaction mechanisms of molecular hydrogen with small neutral and anionic gold clusters. The binding energies of one and two H2 molecules are calculated. The transition states of H2 dissociation on gold clusters are located. In contrast to O2 absorption, DFT produces reasonable results for the H2 binding energies and the barriers to H2 dissociation. The study of the stability of different isomers of C36 carbon clusters is presented in Chapter 4. It is shown that the singlet state of the lowest energy D6h isomer has significant diradical character. The experimental data is explained based on multireference perturbation theory calculations. It is shown that strong electron correlation is responsible for the high stability of D6h isomer observed in experiments. In Chapter 5 the mixed metal-carbon Ti8C12 cluster is studied with the main goal to determine the geometry and ground electronic state of this cluster. It is shown that the Td structure with a 1E ground state is a subject to Jahn-Teller distortion. The distorted D2d and C3v structures are studied with multireference configuration interaction and coupled cluster methods. The D2d structure with a singlet ground state suggested as a ground state of the Ti8C12 cluster. A new approach for solving the many electron Schrodinger equation is proposed in Chapter 6. In contrast to the wave function or the density functional theory approaches, the proposed method uses the first-order reduced density matrix and the diagonal part (density) of the cumulant of the second-order reduced density matrix