A geometric proof of the Kochen-Specker no-go theorem

We give a short geometric proof of the Kochen-Specker no-go theorem for non-contextual hidden variables models. Note added to this version: I understand from Jan-Aake Larsson that the construction we give here actually contains the original Kochen-Specker construction as well as many others (Bell, Conway and Kochen, Schuette, perhaps also Peres).Comment: This paper appeared some years ago, before the author was aware of quant-ph. It is relevant to recent developments concerning Kochen-Specker theorem

Products of Random Matrices

We derive analytic expressions for infinite products of random 2x2 matrices. The determinant of the target matrix is log-normally distributed, whereas the remainder is a surprisingly complicated function of a parameter characterizing the norm of the matrix and a parameter characterizing its skewness. The distribution may have importance as an uncommitted prior in statistical image analysis.Comment: 9 pages, 1 figur

Optimal Bell tests do not require maximally entangled states

Any Bell test consists of a sequence of measurements on a quantum state in space-like separated regions. Thus, a state is better than others for a Bell test when, for the optimal measurements and the same number of trials, the probability of existence of a local model for the observed outcomes is smaller. The maximization over states and measurements defines the optimal nonlocality proof. Numerical results show that the required optimal state does not have to be maximally entangled.Comment: 1 figure, REVTEX

Maximal violation of the CGLMP inequality for infinite dimensional states

We present a much simplified version of the CGLMP inequality for the 2 x 2 x d Bell scenario. Numerical maximization of the violation of this inequality over all states and measurements suggests that the optimal state is far from maximally entangled, while the best measurements are the same as conjectured best measurements for the maximally entangled state. For very large values of d the inequality seems to reach its minimal value given by the probability constraints. This gives numerical evidence for a tight quantum Bell inequality (or generalized Csirelson inequality) for the 2 x 2 x inf scenario.Comment: Introduction shortened, small changes, including new results for dimension of Hilbert space bigger than number of outcomes; 4 pages, 2 figure

Connecting to the Data-Intensive Future of Scientific Research

In recent years enormous amounts of digital data have become available to scientific researchers. This flood of data is transforming the way scientific research is conducted. Independent researchers are in serious need of tools that will help them managed and preserve the large volumes of data being created in their own labs. Data management will not only help researchers get or keep a handle on their data, it will also help them stay relevant and competitive in increasingly strict funding environments. This paper provides summaries of best practices and case studies of data management that relate to three common data management challenges – multitudinous sensor data, short-term data loss, and digital images. We use a combination of open system solutions such as HydroServer Lite, an open system database for time series data, and proprietary tools such as Adobe Photoshop Lightroom. Each lab may require its own unique suite of tools, but these are becoming numerous and readily available, making it easier to archive and share data with collaborators and to discover and integrate published data sets

Contracting Out: A Study of the Honduran Experience

This study was conducted by the National Association of Schools of Public Affairs and Administration (NASPAA) at the request of USAID/Honduras under the terms of NASPAA\u27s Technical Cooperative Agreement with USAID. The study examined the experiences of USAID/Honduras and the Government of Honduras with the contracting out of construction activities in three sectors. The purpose of the study was to document empirical evidence regarding the performance of contracting out as a policy measure to increase private sector initiatives in Honduras

Geodynamic implications for zonal and meridional isotopic patterns across the northern Lau and North Fiji Basins

We present new Sr-Nd-Pb-Hf-He isotopic data for sixty-five volcanic samples from the northern Lau and North Fiji Basin. This includes forty-seven lavas obtained from forty dredge sites spanning an east-west transect across the Lau and North Fiji basins, ten ocean island basalt (OIB)-type lavas collected from seven Fijian islands, and eight OIB lavas sampled on Rotuma. For the first time we are able to map clear north-south and east-west geochemical gradients in 87Sr/86Sr across the northern Lau and North Fiji Basins: lavas with the most geochemically enriched radiogenic isotopic signatures are located in the northeast Lau Basin, while signatures of geochemical enrichment are diminished to the south and west away from the Samoan hotspot. Based on these geochemical patterns and plate reconstructions of the region, these observations are best explained by the addition of Samoa, Rurutu, and Rarotonga hotspot material over the past 4 Ma. We suggest that underplated Samoan material has been advected into the Lau Basin over the past ∼4 Ma. As the slab migrated west (and toward the Samoan plume) via rollback over time, younger and hotter (and therefore less viscous) underplated Samoan plume material was entrained. Thus, entrainment efficiency of underplated plume material was enhanced, and Samoan plume signatures in the Lau Basin became stronger as the trench approached the Samoan hotspot. The addition of subducted volcanoes to the Cook-Austral Volcanic Lineament material, first from the Rarotonga hotspot, then followed by the Rurutu hotspot, contributes to the extreme geochemical signatures observed in the northeast Lau Basin

A Hybrid Sequencing Approach Completes the Genome Sequence of Thermoanaerobacter ethanolicus JW 200

Thermoanaerobacter ethanolicus JW 200 has been identified as a potential sustainable biofuel producer due to its ability to readily ferment carbohydrates to ethanol. A hybrid sequencing approach, combining Oxford Nanopore and Illumina DNA sequence reads, was applied to produce a single contiguous genome sequence of 2,911,280 bp

El Niño and the delayed action oscillator

We study the dynamics of the El Niño phenomenon using the mathematical model of delayedaction oscillator (DAO). Topics such as the influence of the annual cycle, global warming, stochastic influences due to weather conditions and even off-equatorial heat-sinks can all be discussed using only modest analytical and numerical resources. Thus the DAO allows for a pedagogical introduction to the science of El Niño and La Niña while at the same time avoiding the need for large-scale computing resources normally associated with much more sophisticated coupled atmosphere-ocean general circulation models. It is an approach which is ideally suited for student projects both at high school and undergraduate level

Salt Links Dominate Affinity of Antibody HyHEL-5 for Lysozyme through Enthalpic Contributions*

The binding of murine monoclonal antibody HyHEL-5 to lysozyme has been the subject of extensive crystallographic, computational, and experimental investigations. The complex of HyHEL-5 with hen egg lysozyme (HEL) features salt bridges between Fab heavy chain residue Glu50, and Arg45 and Arg68 of HEL. This interaction has been predicted to play a dominant role in the association on the basis of molecular electrostatics calculations. The association of aspartic acid and glutamine mutants at position 50H of the cloned HyHEL-5 Fab with HEL and bobwhite quail lysozyme (BQL), an avian variant bearing an Arg68 ? Lys substitution in the epitope, was characterized by isothermal titration calorimetry and sedimentation equilibrium. Affinities for HEL were reduced by 400-fold (E50HD) and 40,000-fold (E50HQ) (??G� estimated at 4.0 and 6.4 kcal mol?1, respectively). The same mutations reduce affinity for BQL by only 7- and 55-fold, respectively, indicating a reduced specificity for HEL. The loss of affinity upon mutation is in each case primarily due to an unfavorable change in the enthalpy of the interaction; the entropic contribution is virtually unchanged. An enthalpy-entropy compensation exists for each interaction; ?H� decreases, while ?S� increases with temperature. The ?Cp for each mutant interaction is less negative than the wild-type. Mutant-cycle analysis suggests the mutations present in the HyHEL-5 Fab mutants are linked to those present in the BQL with coupling energies between 3 and 4 kcal mol?1