Reversible Dynamics in Strongly Non-Local Boxworld Systems

In order to better understand the structure of quantum theory, or speculate about theories that may supercede it, it can be helpful to consider alternative physical theories. ``Boxworld'' describes one such theory, in which all non-signaling correlations are achievable. In a limited class of multipartite Boxworld systems - wherein all subsystems are identical and all measurements have the same number of outcomes - it has been demonstrated that the set of reversible dynamics is `trivial', generated solely by local relabellings and permutations of subsystems. We develop the convex formalism of Boxworld to give an alternative proof of this result, then extend this proof to all multipartite Boxworld systems, and discuss the potential relevance to other theories. These results lend further support to the idea that the rich reversible dynamics in quantum theory may be the key to understanding its structure and its informational capabilities.Comment: 5 pages + appendice

Information causality from an entropic and a probabilistic perspective

The information causality principle is a generalisation of the no-signalling principle which implies some of the known restrictions on quantum correlations. But despite its clear physical motivation, information causality is formulated in terms of a rather specialised game and figure of merit. We explore different perspectives on information causality, discussing the probability of success as the figure of merit, a relation between information causality and the non-local `inner-product game', and the derivation of a quadratic bound for these games. We then examine an entropic formulation of information causality with which one can obtain the same results, arguably in a simpler fashion.Comment: 7 pages, v2: some references added and minor improvement

Simulating all non-signalling correlations via classical or quantum theory with negative probabilities

Many-party correlations between measurement outcomes in general probabilistic theories are given by conditional probability distributions obeying the non-signalling condition. We show that any such distribution can be obtained from classical or quantum theory, by relaxing positivity constraints on either the mixed state shared by the parties, or the local functions which generate measurement outcomes. Our results apply to generic non-signalling correlations, but in particular they yield two distinct quasi-classical models for quantum correlations.Comment: 6 page

Microscopic colitis

This issue of eMedRef provides information to clinicians on the pathophysiology, diagnosis, and therapeutics of microscopic colitis

Seasonal Variability Of Pristane In Mussels (Mytilus Trossulus) In Prince William Sound, Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2005Pristane (2,6,10,14-tetramethylpentadecane) concentrations in mussels (Mytilus trossulus) increase abruptly during spring in Prince William Sound (PWS), Alaska. This increase is mainly due to ingestion by mussels of pristane-laden feces produced by nearshore zooplanktivores, especially juvenile pink salmon (Oncorhynchus gorbuscha), and I evaluate whether the increase may be used as an index of foraging success, and hence early marine survival, of pink salmon. Pristane is biosynthesized by Neocalanus copepods. Examination of the trophic and temporal distribution of pristane found in 3,007 samples implicates Neocalanus copepods as the source of pristane in PWS. Neocalanus copepods often dominate the zooplankton biomass during spring in PWS. Juvenile pink salmon, preying on Neocalanus , produce pristane-laden feces that are accumulated by mussels 52 times more efficiently than is dissolved pristane. Releases en masse of ~100,000,000 juvenile pink salmon from a hatchery at the peak of the Neocalanus bloom were immediately followed by increases in pristane concentrations of nearby mussels monitored during 1996 and 1998. Accumulation of dissolved pristane, or of fecal pellets produced by Neocalanus copepods, were substantially less important pathways of pristane transfer to mussels. The transfer pathway to mussels via feces produced by zooplanktivores preying on Neocalanus is the basis for a potential linkage between pristane accumulation by mussels and survival of juvenile pink salmon, because it reflects indirectly the magnitude of Neocalanus prey consumed. Annual survival values of hatchery pink salmon were weakly correlated (P = 0.10) with pristane concentrations monitored in mussels at 25 stations distributed throughout PWS from 1995 through 2001. Although Neocalanus copepods are considered important forage for juvenile pink salmon, feeding experiments reported herein confirm previous studies implicating growth inhibition by pristane. Hence, the forage value of Neocalanus copepods may be considerably lower than is usually assumed.Pristane (2,6,10,14-tetramethylpentadecane) concentrations in mussels (Mytilus trossulus) increase abruptly during spring in Prince William Sound (PWS), Alaska. This increase is mainly due to ingestion by mussels of pristane-laden feces produced by nearshore zooplanktivores, especially juvenile pink salmon (Oncorhynchus gorbuscha), and I evaluate whether the increase may be used as an index of foraging success, and hence early marine survival, of pink salmon. Pristane is biosynthesized by Neocalanus copepods. Examination of the trophic and temporal distribution of pristane found in 3,007 samples implicates Neocalanus copepods as the source of pristane in PWS. Neocalanus copepods often dominate the zooplankton biomass during spring in PWS. Juvenile pink salmon, preying on Neocalanus , produce pristane-laden feces that are accumulated by mussels 52 times more efficiently than is dissolved pristane. Releases en masse of ~100,000,000 juvenile pink salmon from a hatchery at the peak of the Neocalanus bloom were immediately followed by increases in pristane concentrations of nearby mussels monitored during 1996 and 1998. Accumulation of dissolved pristane, or of fecal pellets produced by Neocalanus copepods, were substantially less important pathways of pristane transfer to mussels. The transfer pathway to mussels via feces produced by zooplanktivores preying on Neocalanus is the basis for a potential linkage between pristane accumulation by mussels and survival of juvenile pink salmon, because it reflects indirectly the magnitude of Neocalanus prey consumed. Annual survival values of hatchery pink salmon were weakly correlated (P = 0.10) with pristane concentrations monitored in mussels at 25 stations distributed throughout PWS from 1995 through 2001. Although Neocalanus copepods are considered important forage for juvenile pink salmon, feeding experiments reported herein confirm previous studies implicating growth inhibition by pristane. Hence, the forage value of Neocalanus copepods may be considerably lower than is usually assumed

Thermal expansion of graphite-epoxy between 116 K and 366 K

A Priest laser interferometer was developed to measure the thermal strain of composite laminates. The salient features of this interferometer are that: (1) it operates between 116 K and 366 K; (2) it is easy to operate; (3) minimum specimen preparation is required; (4) coefficients of thermal expansion in the range of 0-5 micro epsilon/K can be measured; and (5) the resolution of thermal strain is on the order of micro epsilon. The thermal response of quasi-isotropic, T300/5208, grahite-epoxy composite material was studied with this interferometer. The study showed that: (1) for the material tested, thermal cycling effects are negligible; (2) variability of thermal response from specimen to specimen may become significant at cryogenic temperatures; and (3) the thermal response of 0.6 cm and 2.5 cm wide specimens are the same above room temperature

Hard limits on the postselectability of optical graph states

Coherent control of large entangled graph states enables a wide variety of quantum information processing tasks, including error-corrected quantum computation. The linear optical approach offers excellent control and coherence, but today most photon sources and entangling gates---required for the construction of large graph states---are probabilistic and rely on postselection. In this work, we provide proofs and heuristics to aid experimental design using postselection. We derive a fundamental limitation on the generation of photonic qubit states using postselected entangling gates: experiments which contain a cycle of postselected gates cannot be postselected. Further, we analyse experiments that use photons from postselected photon pair sources, and lower bound the number of classes of graph state entanglement that are accessible in the non-degenerate case---graph state entanglement classes that contain a tree are are always accessible. Numerical investigation up to 9-qubits shows that the proportion of graph states that are accessible using postselection diminishes rapidly. We provide tables showing which classes are accessible for a variety of up to nine qubit resource states and sources. We also use our methods to evaluate near-term multi-photon experiments, and provide our algorithms for doing so.Comment: Our manuscript comprises 4843 words, 6 figures, 1 table, 47 references, and a supplementary material of 1741 words, 2 figures, 1 table, and a Mathematica code listin