9,312 research outputs found

    The Optimal Single Copy Measurement for the Hidden Subgroup Problem

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    The optimization of measurements for the state distinction problem has recently been applied to the theory of quantum algorithms with considerable successes, including efficient new quantum algorithms for the non-abelian hidden subgroup problem. Previous work has identified the optimal single copy measurement for the hidden subgroup problem over abelian groups as well as for the non-abelian problem in the setting where the subgroups are restricted to be all conjugate to each other. Here we describe the optimal single copy measurement for the hidden subgroup problem when all of the subgroups of the group are given with equal a priori probability. The optimal measurement is seen to be a hybrid of the two previously discovered single copy optimal measurements for the hidden subgroup problem.Comment: 8 pages. Error in main proof fixe

    Testing Emergent Gravity on Galaxy Cluster Scales

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    Verlinde's theory of Emergent Gravity (EG) describes gravity as an emergent phenomenon rather than a fundamental force. Applying this reasoning in de Sitter space leads to gravity behaving differently on galaxy and galaxy cluster scales; this excess gravity might offer an alternative to dark matter. Here we test these ideas using the data from the Coma cluster and from 58 stacked galaxy clusters. The X-ray surface brightness measurements of the clusters at 0.1<z<1.20.1 < z < 1.2 along with the weak lensing data are used to test the theory. We find that the simultaneous EG fits of the X-ray and weak lensing datasets are significantly worse than those provided by General Relativity (with cold dark matter). For the Coma cluster, the predictions from Emergent Gravity and General Relativity agree in the range of 250 - 700 kpc, while at around 1 Mpc scales, EG total mass predictions are larger by a factor of 2. For the cluster stack the predictions are only in good agreement at around the 1 - 2 Mpc scales, while for r≳10r \gtrsim 10 Mpc EG is in strong tension with the data. According to the Bayesian information criterion analysis, GR is preferred in all tested datasets; however, we also discuss possible modifications of EG that greatly relax the tension with the data.Comment: 19 pages, 5 figures, 5 tables, accepted for publication on JCA

    Arkansas Small-Grain Cultivar Performance Tests 2004-2005

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    Small-grain cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for smallgrain producers

    Recurrence rates for SIDS - the importance of risk stratification

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    Objective: To investigate the importance of stratification by risk factors in computing the probability of a second SIDS in a family. Design: Simulation Study Background: The fact that a baby dies suddenly and unexpectedly means that there is a raised probability that the baby’s family have risk factors associated with Sudden Infant Death Syndrome (SIDS). Thus one cannot consider the risk of a subsequent death to be that of the general population. The Confidential Enquiry into Stillbirths and Deaths in Infancy (CESDI)6 identified three major social risk factors: smoking, age1, and unemployed/unwaged as major risk factors. It gave estimates of risk for families with different numbers of these risk factors. We investigate whether it is reasonable to assume that, conditional on these risk factors, the risk of a second event is independent of the risk of the first and as a consequence one can square the risks to get the risk of two SIDS in a family. We have used CESDI data to estimate the probability of a second SID in a family under different plausible scenarios of the prevalence of the risk factors. We have applied the model to make predictions in the Care of Next Infant (CONI) study7. Results: The model gave plausible predictions. The CONI study observed 18 second SIDS. Our model predicted 14 (95% prediction interval 7 to 21). Conclusion: When considering the risk of a subsequent SIDS in a family one should always take into account the known risk factors. If all risks have been identified, then conditional on these risks, the risk of two events is the product of the individual risks However for a given family we cannot quantify the magnitude of the increased risk because of other possible risk factors not accounted for in the model

    Pacific Coast Agricultural Export Association v. Sunkist Growers, Inc.

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    A Comparison of Price Differentials in the Chain and Independent Grocery Stores of Logan, Utah

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    This study is the result of two separate surveys of the retail grocery stores in Logan, Utah. The primary purpose of these surveys was to make a detailed study of price differentials as they exist between the stores of different kind, class, location and size. Logan was chosen for this survey for a number of reasons: (1) It is typical of many Rocky Mountain cities for size. (2) There is no one industry that completely dominates the economy of the city. (3) There are sufficient stores in kind and number to give the necessary data. (4) Besides the local independent stores that are in operation, there is a national chain system represented by Safeway Stores, Inc. and a small state chain represented by the American Food Store. The problem was to survey the Logan city grocery stores for price data on food commodities in sufficient number to indicated the price differentials that exist within the stores. To facilitate this the local stores were segregated into four distinct classes, namely: (1) national chains, (2) a small state chain, (3) large city independents, and (4) neighborhood stores. The prices found in the chain systems were used as a bases for the comparisons that are made between both the chain stores and the two groups of independent stores. The study has proven valuable in that price differentials have been discovered to exist between the various commodity groups, as well as within the individual items. These differentials have varied with the commodity and within the different classifications of stores. Many of the pricing policies that are being practiced in the Logan stores are representative of market conditions as they exist in other cities within the Rocky area and might justifiably be applied to these communities with the expectations that similar results would occur

    Atomic displacements accompanying deformation twinning: shears and shuffles

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    Deformation twins grow by the motion of disconnections along their interfaces, thereby coupling shear with migration. Atomic-scale simulations of this mechanism have advanced to the point where the trajectory of each atom can be followed as it transits from a site in the shrinking grain, through the interface, and onwards to a site in the growing twin. Historically, such trajectories have been factorised into shear and shuffle components according to some defined convention. In the present article, we introduce a method of factorisation consistent with disconnection motion. This procedure is illustrated for the case of {10-12} twinning in hcp materials, and shown to agree with simulated atomic trajectories for Zr.Peer ReviewedPostprint (published version

    A double-helix neutron detector using micron-size B-10 powder

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    A double-helix electrode configuration is combined with a 10^{10}B powder coating technique to build large-area (9 in Ă—\times 36 in) neutron detectors. The neutron detection efficiency for each of the four prototypes is comparable to a single 2-bar 3^3He drift tube of the same length (36 in). One unit has been operational continuously for 18 months and the change of efficiency is less than 1%. An analytic model for pulse heigh spectra is described and the predicted mean film thickness agrees with the experiment to within 30%. Further detector optimization is possible through film texture, power size, moderator box and gas. The estimated production cost per unit is less than 3k US\$ and the technology is thus suitable for deployment in large numbers
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