Decoherence-free quantum-information processing using dipole-coupled qubits

We propose a quantum-information processor that consists of decoherence-free logical qubits encoded into arrays of dipole-coupled qubits. High-fidelity single-qubit operations are performed deterministically within a decoherence-free subsystem without leakage via global addressing of bichromatic laser fields. Two-qubit operations are realized locally with four physical qubits, and between separated logical qubits using linear optics. We show how to prepare cluster states using this method. We include all non-nearest-neighbor effects in our calculations, and we assume the qubits are not located in the Dicke limit. Although our proposal is general to any system of dipole-coupled qubits, throughout the paper we use nitrogen-vacancy (NV) centers in diamond as an experimental context for our theoretical results.Comment: 7 pages, 5 figure

Identification of single-site gold catalysis in acetylene hydrochlorination

There remains considerable debate over the active form of gold under operating conditions of a recently validated gold catalyst for acetylene hydrochlorination. We have performed an in situ x-ray absorption fine structure study of gold/carbon (Au/C) catalysts under acetylene hydrochlorination reaction conditions and show that highly active catalysts comprise single-site cationic Au entities whose activity correlates with the ratio of Au(I):Au(III) present. We demonstrate that these Au/C catalysts are supported analogs of single-site homogeneous Au catalysts and propose a mechanism, supported by computational modeling, based on a redox couple of Au(I)-Au(III) species. View Full Tex

Identification of a Core Amino Acid Motif within the α Subunit of GABAARs that Promotes Inhibitory Synaptogenesis and Resilience to Seizures

The fidelity of inhibitory neurotransmission is dependent on the accumulation of γ-aminobutyric acid type A receptors (GABAARs) at the appropriate synaptic sites. Synaptic GABAARs are constructed from α(1-3), β(1-3), and γ2 subunits, and neurons can target these subtypes to specific synapses. Here, we identify a 15-amino acid inhibitory synapse targeting motif (ISTM) within the α2 subunit that promotes the association between GABAARs and the inhibitory scaffold proteins collybistin and gephyrin. Using mice in which the ISTM has been introduced into the α1 subunit (Gabra1-2 mice), we show that the ISTM is critical for axo-axonic synapse formation, the efficacy of GABAergic neurotransmission, and seizure sensitivity. The Gabra1-2 mutation rescues seizure-induced lethality in Gabra2-1 mice, which lack axo-axonic synapses due to the deletion of the ISTM from the α2 subunit. Taken together, our data demonstrate that the ISTM plays a critical role in promoting inhibitory synapse formation, both in the axonic and somatodendritic compartments

Evaluation of Pooled Serum and ‘Meat-Juice’ in a Salmonella ELISA for Pig Herds

Samples of ‘meat-juice’, serum, caecal contents and carcase swabs from 420 pigs from 20 finishing farms were tested for Salmonella bacteriologically and serologically by ELISA on individual samples or on pools of serum or meat juice. In addition pooled floor faeces were taken from the finishing pens on the farm of origin

Comparison of two commercial ELISA kits and bacteriology for Salmonella monitoring in pig herds

Samples of ‘meat-juice’ and serum from 170 pigs from 20 finishing farms were tested for Salmonella using two commercial ELISA kit tests. In parallel samples from caecal contents and pooled pen faeces from the farm were tested by culture. Both ELISA’s gave significantly correlated results with each other but only ELISA B, at a 20 % calculated OD % on ‘meat juice’, gave a result which correlated significantly with the percentage of positive pen faeces. None of the ELISA tests correlated with caecal positives and the 10 % cut-off level was shown to be unsuitable for monitoring commercial herds

Yet another breakdown point notion: EFSBP - illustrated at scale-shape models

The breakdown point in its different variants is one of the central notions to quantify the global robustness of a procedure. We propose a simple supplementary variant which is useful in situations where we have no obvious or only partial equivariance: Extending the Donoho and Huber(1983) Finite Sample Breakdown Point, we propose the Expected Finite Sample Breakdown Point to produce less configuration-dependent values while still preserving the finite sample aspect of the former definition. We apply this notion for joint estimation of scale and shape (with only scale-equivariance available), exemplified for generalized Pareto, generalized extreme value, Weibull, and Gamma distributions. In these settings, we are interested in highly-robust, easy-to-compute initial estimators; to this end we study Pickands-type and Location-Dispersion-type estimators and compute their respective breakdown points.Comment: 21 pages, 4 figure

Drying of complex suspensions

We investigate the 3D structure and drying dynamics of complex mixtures of emulsion droplets and colloidal particles, using confocal microscopy. Air invades and rapidly collapses large emulsion droplets, forcing their contents into the surrounding porous particle pack at a rate proportional to the square of the droplet radius. By contrast, small droplets do not collapse, but remain intact and are merely deformed. A simple model coupling the Laplace pressure to Darcy's law correctly estimates both the threshold radius separating these two behaviors, and the rate of large-droplet evacuation. Finally, we use these systems to make novel hierarchical structures.Comment: 4 pages, 4 figure

Energy-dense snacks can have the same expected satiation as sugar-containing beverages

AbstractSugar-sweetened beverages (SSBs) are thought to be problematic for weight management because energy delivered in liquid form may be less effective at suppressing appetite than solid foods. However, little is known about the relative ‘expected satiation’ (anticipated fullness) of SSBs and solid foods. This is relevant because expected satiation is an important determinant of portion selection and energy intake. Here, we used a method of constant stimuli to assess the expected satiation of test meals that were presented in combination with different caloric and non-caloric beverages (500 ml) (Experiment 1 and 2), as well as with high-energy solid snack foods (Experiment 2). All energy-containing beverages and snack foods were presented in 210 kcal portions. Both experiments found that expected satiation was greater for meals containing caloric versus non-caloric beverages (201.3 ± 17.3 vs. 185.4 ± 14.1 kcal in Experiment 2; p < 0.05). Further, Experiment 2 showed that this difference was greater in participants who were familiar with our test beverages, indicating a role for learning. Notably, we failed to observe a significant difference in expected satiation between any of the caloric beverages and snack foods in Experiment 2 (range: 192.5–205.2 kcal; p = 0.87). This finding suggests that it may be more appropriate to consider beverages and solid foods on the same continuum, recognizing that the expected satiation of some solid foods is as weak as some beverages

An Overview of The VERITAS Prototype Telescope And Camera

VERITAS (the Very Energetic Radiation Imaging Telescope Array System) is the next generation ground-based gamma-ray observatory that is being built in southern Arizona by a collaboration of ten institutions in Canada, Ireland, the U.K. and the U.S.A. VERITAS is designed to operate in the range from 50 GeV to 50 TeV with optimal sensitivity near 200 GeV; it will effectively overlap with the next generation of space-based gamma-ray telescopes. The first phase of VERITAS, consisting of four telescopes of 12 m aperture, will be operational by the time of the GLAST launch in 2007. Eventually the array will be expanded to include the full array of seven telescopes on a filled hexagonal grid of side 80 m. A prototype VERITAS telescope with a reduced number of mirrors and signal channels has been built. Its design and performance is described here. The prototype is scheduled to be upgraded to a full 499 pixel camera with 350 mirrors during the autumn of 2004.Comment: 8 pages, 6 figures, Proceedings of the Conference "The Multiwavelength Approach to Unidentified Sources", to appear in the journal Astrophysics and Space Scienc