An extension of SPARQL for expressing qualitative preferences

In this paper we present SPREFQL, an extension of the SPARQL language that allows appending a PREFER clause that expresses "soft" preferences over the query results obtained by the main body of the query. The extension does not add expressivity and any SPREFQL query can be transformed to an equivalent standard SPARQL query. However, clearly separating preferences from the "hard" patterns and filters in the WHERE clause gives queries where the intention of the client is more cleanly expressed, an advantage for both human readability and machine optimization. In the paper we formally define the syntax and the semantics of the extension and we also provide empirical evidence that optimizations specific to SPREFQL improve run-time efficiency by comparison to the usually applied optimizations on the equivalent standard SPARQL query.Comment: Accepted to the 2017 International Semantic Web Conference, Vienna, October 201

A comparison of aerosol chemical and optical properties from the 1st and 2nd Aerosol Characterization Experiments

Shipboard measurements of aerosol chemical composition and optical properties were made during both ACE-1 and ACE-2. ACE-1 focused on remote marine aerosol minimally perturbed by continental sources. ACE-2 studied the outflow of European aerosol into the NE Atlantic atmosphere. A variety of air masses were sampled during ACE-2 including Atlantic, polar, Iberian Peninsula, Mediterranean, and Western European. Reported here are mass size distributions of non-sea salt (nss) sulfate, sea salt, and methanesulfonate and submicron and supermicron concentrations of black and organic carbon. Optical parameters include submicron and supermicron aerosol scattering and backscattering coefficients at 550 nm, the absorption coefficient at 550±20 nm, the Ångström exponent for the 550 and 700 nm wavelength pair, and single scattering albedo at 550 nm. All data are reported at the measurement relative humidity of 55%. Measured concentrations of nss sulfate aerosol indicate that, relative to ACE-1, ACE-2 aerosol during both marine and continental flow was impacted by continental sources. Thus, while sea salt controlled the aerosol chemical composition and optical properties of both the submicron and supermicron aerosol during ACE-1, it played a relatively smaller role in ACE-2. This is confirmed by the larger average Ångström exponent for ACE-2 continental aerosol of 1.2±0.26 compared to the ACE-1 average of -0.03±0.38. The depletion of chloride from sea salt aerosol in ACE-2 continental air masses averaged 55±25% over all particle sizes. This compares to the ACE-2 marine average of 4.8±18% and indicates the enhanced interaction of anthropogenic acids with sea salt as continental air masses are transported into the marine atmosphere. Single scattering albedos averaged 0.95±0.03 for ACE-2 continental air masses. Averages for ACE-2 and ACE-1 marine air masses were 0.98±0.01 and 0.99±0.01, respectively

Secure Distributed Virtual Conferencing: Multicast or Bust

We describe a secure distributed virtual conferencing application (SDVC) that provides high quality streaming video and audio using IP multicast for efficient distribution, using strong authentication via cryptographic means and optionally providing fully encrypted communication without sacrificing quality of the medium or the user experience. We summarize our experiences with SDVC in a recent live demonstration and conclude with a discussion of future plans.http://deepblue.lib.umich.edu/bitstream/2027.42/107912/1/citi-tr-99-1.pd

Local symmetry properties of pure 3-qubit states

Entanglement types of pure states of 3 qubits are classified by means of their stabilisers in the group of local unitary operations. It is shown that the stabiliser is generically discrete, and that a larger stabiliser indicates a stationary value for some local invariant. We describe all the exceptional states with enlarged stabilisers.Comment: 32 pages, 5 encapsulated PostScript files for 3 figures. Published version, with minor correction

Measurement of the Branching Fractions for D^0 → π^-e^+v_e and D^0 → + K^-e^+V_e and Determination of │V_(cd)/V_(cs)│^2

Measurements of the exclusive branching fractions B(D^0→π^-e^+ν_e) and B(D^0→K^-e^+ν_e), using data collected at the ψ(3770) with the Mark III detector at the SLAC e^+e^- storage ring SPEAR, are used to determine the ratio of the Kobayashi-Maskawa matrix elements │V_(cd)/V_(cs)│^2 =0.057_(-0.015)^(+0.038)±0.005

Search for the decay D^0→K^0e^+e^-

A search for the decay of the charmed meson D^0→K^0e^+e^- is presented, based on data collected at the ψ(3770) resonance with the Mark III detector at the SLAC storage ring SPEAR. No evidence for this process is found, resulting in an upper limit on the decay branching ratio of 1.7×10^(-3) at the 90% confidence level

On the Mixing of the Scalar Mesons f0(1370)f_0(1370), f0(1500)f_0(1500) and f0(1710)f_0(1710)

Based on a $3\times3$ mass matrix describing the mixing of the scalar states $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$, the hadronic decays of the three states are investigated. Taking into account the two possible assumptions concerning the mass level order of the bare states $|N>=|u\bar{u}+d\bar{d}>/\sqrt{2}$, $|S>=|s\bar{s}>$ and $|G>=|gg>$ in the scalar sector, $M_G > M_S > M_N$ and $M_G > M_N > M_S$, we obtain the glueball-quarkonia content of the three states by solving the unlinear equations. Some predictions about the decays of the three states in two cases are presented, which can provide a stringent consistency check of the two assumptions.Comment: revtex 10 pages, 1 eps figur

Parallel transport in an entangled ring

This paper defines a notion of parallel transport in a lattice of quantum particles, such that the transformation associated with each link of the lattice is determined by the quantum state of the two particles joined by that link. We focus particularly on a one-dimensional lattice--a ring--of entangled rebits, which are binary quantum objects confined to a real state space. We consider states of the ring that maximize the correlation between nearest neighbors, and show that some correlation must be sacrificed in order to have non-trivial parallel transport around the ring. An analogy is made with lattice gauge theory, in which non-trivial parallel transport around closed loops is associated with a reduction in the probability of the field configuration. We discuss the possibility of extending our result to qubits and to higher dimensional lattices.Comment: 31 pages, no figures; v2 includes a new example of a qubit rin

Natural Thermal and Magnetic Entanglement in 1D Heisenberg Model

We investigate the entanglement between any two spins in a one dimensional Heisenberg chain as a function of temperature and the external magnetic field. We find that the entanglement in an antiferromagnetic chain can be increased by increasing the temperature or the external field. Increasing the field can also create entanglement between otherwise disentangled spins. This entanglement can be confirmed by testing Bell's inequalities involving any two spins in the solid.Comment: 4 pages, 5 figure