1,378 research outputs found

    A geometrical formulation of the μ-lower bound problem

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    A new problem formulation for the structured singular value μ in the case of purely real (possibly repeated) uncertainties is presented. The approach is based on a geometrical interpretation of the singularity constraint arising in the μ lower bound problem. An interesting feature of this problem formulation is that the resulting parametric search space is independent of the number of times any parameter is repeated in the structured uncertainty matrix. A corresponding lower bound algorithm combining randomisation and optimisation methods is developed, and some probabilistic performance guarantees are derived. The potential usefulness of the proposed approach is demonstrated on two high-order real μ analysis problems from the aerospace and systems biology literature

    Power Dependence and Power Paradoxes in Bargaining

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    [Excerpt] What this article (and our larger program of work) is designed to demonstrate is that these very simple ideas represent a particularly suitable starting point for understanding the power struggle between parties who regularly engage in negotiation. Specifically, in this article we show that the approach contains certain paradoxes regarding the acquisition and use of power in an ongoing bargaining relationship. The dependence framework treats the ongoing relationship as a power struggle in which each party tries to maneuver itself into a favorable power position

    IUPAC-NIST solubility data series. 81. Hydrocarbons with water and seawater-revised and updated. Part 5. C7 hydrocarbons with water and heavy water

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    The mutual solubility and related liquid-liquid equilibria of C7 hydrocarbons with water and heavy water are exhaustively and critically reviewed. Reports of experimental determination of solubility in 23 chemically distinct binary systems that appeared in the primary literature prior to end of 2002 are compiled. For 9 systems sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a new method based on the evaluation of the all experimental data for a given homologous series of aliphatic and aromatic hydrocarbons was used

    An agronomic and economic evaluation of weed control systems in the Pernambuco agreste

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    Foram realizados dois experimentos com milho (Zea mays. var. Azteca) e feijão (Phaseolus vulgaris, var. Costa Rica), no município de Caruaru, PE, durante o ano agrícola de 1974, para avaliar a eficiência e relativa rentabilidade de 12 diferentes sistemas - manuais, químicos, mecânicas e integrados - de controle de ervas daninhas.Nas parcelas sem nenhum controle, as produções de feijão e milho atingiram apenas 26 e 5%, respectivamente, das produções médias obtidas com controle total. Os sistemas de controle parcial apresentaram produções de apenas 64 e 46% das produções obtidas em parcelas com controle total em milho e feijão, respectivamente.As diferenças nos rendimentos dos sistemas pertencentes aos mesmos níveis de controle, geralmente não foram estatisticamente significativas, indicando perfeita substituição entre técnicas de controle manuais, mecânicas e químicas, durante o período em que estas foram executadas. O sistema mais eficiente para milho isolado, sob condições locais e preços de 1974, foi a aplicação, na quantidade de 1,5 kg de ingrediente ativo (i.a.) por hectare, do berbicida pré-emergente, simazine, o qual apresentou relação beneficio/custo de 6,03. Se fosse possível controlar as invasoras com uma operação mecânica, este método seria mais eficiente que o anterior. O sistema mais eficiente para feijão foi o de duas cultivações de tração animal suplementadas pela enxada nas fileiras, o qual apresentou relação benefício/custo de 3,40. Entretanto, evidências de outras fontes de pesquisa indicam que o maior espaçamento entre fileiras, necessário neste caso para uso de tração animal e operação com microtrator, pode reduzir o rendimento, e que tornaria os cultivadores ineficientes na monocultura do feijão. Se o uso de cultivadores não fosse possível, o tradicional controle com enxada seria o mais eficiente método para controlar as ervas daninhas em feijão.Two identical experiments were conducted in corn (Zea mays, Var. Azteca) and beans (Phaseolus vulgaris, var. Costa Rica) in Caruaru, Pernambuco State, Brazil, during 1974, to evaluate the effectiveness and relative profitability of 12 different manual, mechanical, chemical and integrated weed control treatments. Control plots averaged only 5 and 26% of the production achieved on plots receiving complete weed control for corn and beans, respectively. Partial control systems - mechanical cultivation between rows only, or herbicides within rows only - produced yields averaging 64 and 46% of corn and beans yields obtained with complete control systems such as cultivations between and within rows. Differences in yields among systems belonging to the same level of central generally were not statistically significant, indicating perfect technical substitutability among manual, mechanical and chemical techniques as long as weed control coverage was complete. The most efficient system for monoculture corn under local conditions and 1974 prices was application of the preemergence herbicide simazine at 1.5 kg active ingredient per ha which yielded a benefit/cost ratio of 6.03. However if only one rather than two manual or mechanical cultivations was sufficient to give complete control, thon one cultivation would be more efficient than herbicide application. The most efficient system for beans in these experiments was two animal traction hoeings within rows, which yielded a benefit/cost ratio of 3.40. Evidence from other sources, however, indicated that the wider row spacing required for animal traction or micro-trator cultivators can reduce yields which whould make cultivators inefficient in monoculture beans. If cultivator use was precluded, traditional hoeing remained the most efficient weed control method for beans

    Direct amplification of nodD from community DNA reveals the genetic diversity of Rhizobium leguminosarum in soil

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    Sequences of nodD, a gene found only in rhizobia, were amplified from total community DNA isolated from a pasture soil. The polymerase chain reaction (PCR) primers used, Y5 and Y6, match nodD from Rhizobium leguminosarum biovar trifolii, R. leguminosarum biovar viciae and Sinorhizobium meliloti. The PCR product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (RFLP) types] and 15 clones identified as viciae (seven RFLP types). These identifications were confirmed by sequencing. There were no clones related to S. meliloti nodD. For comparison, 122 strains were isolated from nodules of white clover (Trifolium repens) growing at the field site, and 134 from nodules on trap plants of T. repens inoculated with the soil. The nodule isolates were of four nodD RFLP types, with 77% being of a single type. All four of these patterns were also found among the clones from soil DNA, and the same type was the most abundant, although it made up only 34% of the trifolii-like clones. We conclude that clover selects specific genotypes from the available soil population, and that R. leguminosarum biovar trifolii was approximately five times more abundant than biovar viciae in this pasture soil, whereas S. meliloti was rare

    Determining Reheating Temperature at Colliders with Axino or Gravitino Dark Matter

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    After a period of inflationary expansion, the Universe reheated and reached full thermal equilibrium at the reheating temperature T_R. In this work we point out that, in the context of effective low-energy supersymmetric models, LHC measurements may allow one to determine T_R as a function of the mass of the dark matter particle assumed to be either an axino or a gravitino. An upper bound on their mass may also be derived.Comment: 19 pages, some improvements, JHEP versio

    Mineral exploration in the Cockermouth area, Cumbria. Part 2: follow-up surveys

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    This report describes the results of geochemical, geological and geophysical surveys across three small areas of Carboniferous and Lower Palaeozoic rocks along the northern margin of the English Lake District. The areas were chosen from the appraisal of regional-scale survey data described by Cooper et al. (1991). In two of the areas, Ruthwaite and Tallentire, the objective was to provide more information on the extent and magnitude of fracture-controlled epigenetic baryte and base metal mineralisation. In the third area, at Whitrigg, brief surveys were carried out to aid the interpretation of unexplained geochemical and geophysical anomalies found during two projects carried out under the Mineral Exploration and Investment Grants Act (MEIGA). At Ruthwaite, where a mine formerly worked baryte from a fault separating Lower Palaeozoic and Carboniferous rocks, surface indications of further baryte mineralisation were found. Soil analyses indicated that mineralisation may be present along the continuation of the faultline worked at Ruthwaite and in the Eycott Volcanic Group rocks to the south of it. In this area relatively small, but in some circumstances perhaps economically attractive, deposits of baryte may be present under drift cover. In the Tallentire Hill area, geological mapping followed by traverse-based soil sampling showed that fracture-controlled mineralisation is widespread in the Carboniferous (Dinantian and Namurian) rocks. The fracture fillings consist dominantly of baryte, often accompanied by carbonate, with traces of copper and mercury. Where seen at surface the fracture fillings are too small, patchy and low-grade to be of any economic importance. Baryte mineralisation also occurs locally as patchy impregnations in sandstones. These are considered to be epigenetic deposits related to the fracture-controlled mineralisation. Trial geophysical surveys suggested that electrical methods may be useful in determining the extent of the mineralised sandstone. There is a possibility that more extensive baryte deposits may be present in the limestone succession underlying the mineralised sandstones. In the Whitrigg area, Carboniferous rocks are separated from Lower Palaeozoic rocks of the Eycott Volcanic Group by the easterly-trending Boundary Fault and north-westerly-trending Bothel Fault. Evidence from an old mineral working and the results of a soil survey indicate that patchy, epigenetic, fracture-controlled baryte and base metal mineralisation occurs along the Bothel Fault and, locally, in the adjacent rocks. A feature of this mineralisation is the presence of mercury, which is most abundant in a sample of brecciated and altered rock from the Eycott Volcanic Group. Prominent base metal in soil anomalies discovered by MEIGA-funded projects near Stangerhill are not associated with barium anomalies. It was concluded that these soil anomalies are most likely to be caused by secondary concentration in overburden, and that the source of metals may be a sub-cropping metalliferous horizon within the Carboniferous succession or, more probably, fracture-controlled mineralisation. Trial geophysical surveys carried out in all three areas indicated that in ground free of artificial sources the VLF(EM) and conductivity mapping methods could be useful for tracing faults beneath drift and providing information on drift thickness. Closely-spaced soil sampling proved effective for detecting mineralisation in areas where the drift cover is thin, and a trial soil-gas survey showed that this technique could also be useful for tracing faults beneath drift

    Patient-Powered Research Networks of the Autoimmune Research Collaborative: Rationale, Capacity, and Future Directions

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    Patient-Powered Research Networks (PPRNs) are US-based registry infrastructures co-created by advocacy groups, patient research partners, academic investigators, and other healthcare stakeholders. Patient-Powered Research Networks collect information directly from patients to conduct and disseminate the results of patient-centered/powered research that helps patients make more informed decisions about their healthcare. Patient-Powered Research Networks gather and utilize real-world data and patient-reported outcomes to conduct comparative effectiveness, safety, and other research, and leverage the Internet to accomplish this effectively and efficiently. Four PPRNs focused on autoimmune and immune-mediated conditions formed the Autoimmune Research Collaborative: ArthritisPower (rheumatoid arthritis, spondyloarthritis, and other rheumatic and musculoskeletal diseases), IBD Partners (inflammatory bowel disease), iConquerMS (multiple sclerosis), and the Vasculitis PPRN (vasculitis). The Autoimmune Research Collaborative aims to inform the healthcare decision making of patients, care partners, and other stakeholders, such as clinicians, regulators, and payers. Illustrated by practical applications from the Autoimmune Research Collaborative and its constituent PPRNs, this article discusses the shared capacities and challenges of the PPRN model, and the opportunities presented by collaborating across autoimmune conditions to design, conduct, and disseminate patient-centered outcomes research

    Spin-3/2 Nucleon and Delta Baryons in Lattice QCD

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    We present first results for masses of spin-3/2 N and Delta baryons in lattice QCD using Fat-Link Irrelevant Clover (FLIC) fermions. Spin-3/2 interpolating fields providing overlap with both spin-3/2 and spin-1/2 states are considered. In the isospin-1/2 sector, we observe, after appropriate spin and parity projection, a strong signal for the J^P=3/2^- state together with a weak but discernible signal for the 3/2^+ state with a mass splitting near that observed experimentally. We also find good agreement between the 1/2^+/- masses and earlier nucleon mass simulations with the standard spin-1/2 interpolating field. For the isospin-3/2 Delta states, clear mass splittings are observed between the various 1/2^+/- and 3/2^+/- channels, with the calculated level orderings in good agreement with those observed empirically.Comment: 17 pages, 8 figures, 2 table

    In vitro anti-diabetic activity of flavonoids and pheophytins from Allophylus cominia Sw . on PTP1B, DPPIV, alpha-glucosidase and alpha-amylase enzymes

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    BACKGROUND: Ethno-botanical information from diabetic patients in Cuba led to the identification of Allophylus cominia as a possible source of new drugs for the treatment of type 2 diabetes mellitus (T2-DM). EXPERIMENTAL: Chemical characterization of the extracts from A. cominia was carried out using chromatographic and spectroscopic methods. The extracts were tested for their activity on PTP1B, DPPIV, α-glucosidase enzymes and α-amylase. RESULTS: The flavonoid rich fractions from A. cominia inhibited DPPIV enzyme (75.3±2.33%) at 30µg/ml and produced a concentration-dependent inhibition against DPPIV with a Ki value of 2.6µg/ml. At 30µg/ml, flavonoids and pheophytins extracts significantly inhibited PTP1B enzyme (100±2.6% and 68±1% respectively). The flavonoids, pheophytin A and pheophytin B fractions showed significant concentration-dependent inhibition against PTP1B with Ki values of 3µg/ml, 0.64µg/ml and 0.88µg/ml respectively. At 30µg/ml, the flavonoid fraction significantly inhibited α-glucosidase enzyme (86±0.3%) in a concentration-dependent pattern with a Ki value of 2µg/ml. None of the fractions showed significant effects on α-amylase. Fatty acids, tannins, pheophytins A and B, and a mixture of flavonoids were detected in the methanolic extract from A. cominia. The identified flavonoids were mearnsitrin, quercitrin, quercetin-3-alloside, and naringenin-7-glucoside. CONCLUSION: The pharmacological effects of the extracts from A. cominia earlier observed in experimental diabetic models was confirmed in this study. Thus a new drug or formulation for the treatment of T2-DM could be developed from A. cominia
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