Non-Newtonian fluid flow through three-dimensional disordered porous media

We investigate the flow of various non-Newtonian fluids through three-dimensional disordered porous media by direct numerical simulation of momentum transport and continuity equations. Remarkably, our results for power-law (PL) fluids indicate that the flow, when quantified in terms of a properly modified permeability-like index and Reynolds number, can be successfully described by a single (universal) curve over a broad range of Reynolds conditions and power-law exponents. We also study the flow behavior of Bingham fluids described in terms of the Herschel-Bulkley model. In this case, our simulations reveal that the interplay of ({\it i}) the disordered geometry of the pore space, ({\it ii}) the fluid rheological properties, and ({\it iii}) the inertial effects on the flow is responsible for a substantial enhancement of the macroscopic hydraulic conductance of the system at intermediate Reynolds conditions. This anomalous condition of ``enhanced transport'' represents a novel feature for flow in porous materials.Comment: 5 pages, 5 figures. This article appears also in Physical Review Letters 103 194502 (2009

Theoretical studies of the historical development of the accounting discipline: a review and evidence

Many existing studies of the development of accounting thought have either been atheoretical or have adopted Kuhn's model of scientific growth. The limitations of this 35-year-old model are discussed. Four different general neo-Kuhnian models of scholarly knowledge development are reviewed and compared with reference to an analytical matrix. The models are found to be mutually consistent, with each focusing on a different aspect of development. A composite model is proposed. Based on a hand-crafted database, author co-citation analysis is used to map empirically the entire literature structure of the accounting discipline during two consecutive time periods, 1972–81 and 1982–90. The changing structure of the accounting literature is interpreted using the proposed composite model of scholarly knowledge development

The DLV System for Knowledge Representation and Reasoning

This paper presents the DLV system, which is widely considered the state-of-the-art implementation of disjunctive logic programming, and addresses several aspects. As for problem solving, we provide a formal definition of its kernel language, function-free disjunctive logic programs (also known as disjunctive datalog), extended by weak constraints, which are a powerful tool to express optimization problems. We then illustrate the usage of DLV as a tool for knowledge representation and reasoning, describing a new declarative programming methodology which allows one to encode complex problems (up to $\Delta^P_3$-complete problems) in a declarative fashion. On the foundational side, we provide a detailed analysis of the computational complexity of the language of DLV, and by deriving new complexity results we chart a complete picture of the complexity of this language and important fragments thereof. Furthermore, we illustrate the general architecture of the DLV system which has been influenced by these results. As for applications, we overview application front-ends which have been developed on top of DLV to solve specific knowledge representation tasks, and we briefly describe the main international projects investigating the potential of the system for industrial exploitation. Finally, we report about thorough experimentation and benchmarking, which has been carried out to assess the efficiency of the system. The experimental results confirm the solidity of DLV and highlight its potential for emerging application areas like knowledge management and information integration.Comment: 56 pages, 9 figures, 6 table

Impact of Scottish smoke-free legislation on smoking quit attempts and prevalence

<p><b>Objectives:</b> In Scotland, legislation was implemented in March 2006 prohibiting smoking in all wholly or partially enclosed public spaces. We investigated the impact on attempts to quit smoking and smoking prevalence.</p> <p><b>Methods:</b> We performed time series models using Box-Jenkins autoregressive integrated moving averages (ARIMA) on monthly data on the gross ingredient cost of all nicotine replacement therapy (NRT) prescribed in Scotland in 2003–2009, and quarterly data on self-reported smoking prevalence between January 1999 and September 2010 from the Scottish Household Survey.</p> <p><b>Results:</b> NRT prescription costs were significantly higher than expected over the three months prior to implementation of the legislation. Prescription costs peaked at £1.3 million in March 2006; £292,005.9 (95% CI £260,402.3, £323,609, p<0.001) higher than the monthly norm. Following implementation of the legislation, costs fell exponentially by around 26% per month (95% CI 17%, 35%, p<0.001). Twelve months following implementation, the costs were not significantly different to monthly norms. Smoking prevalence fell by 8.0% overall, from 31.3% in January 1999 to 23.7% in July–September 2010. In the quarter prior to implementation of the legislation, smoking prevalence fell by 1.7% (95% CI 2.4%, 1.0%, p<0.001) more than expected from the underlying trend.</p> <p><b>Conclusions:</b> Quit attempts increased in the three months leading up to Scotland's smoke-free legislation, resulting in a fall in smoking prevalence. However, neither has been sustained suggesting the need for additional tobacco control measures and ongoing support.</p&gt

Genetic analysis indicate superiority of perfomance of cape goosberry (Physalis peruviana L.) hybrids

The use of hybrids as a new type of cape gooseberry (Physalis peruviana L.) cultivars could improve yield in this crop, but little or no information is available on hybrid perfomance. We studied several vegetative characters, yield, fruit weight and fruit shape, soluble solids content (SSC), titratable acidity (TA) and ascorbic acid content (AAC) in three hybrids of cape gooseberry and their parents grown outdoors and in a glasshouse. The highest yields were obtained with hybrids, specially in a glasshouse. Interaction dominance environment for yield was very important; a higher dominance effect was detected in the glasshouse, than that observed outdoors. Quality characters were highly affected by the environment and showed variable results for the different families. For fruit composition traits, the additive and additive environment interactions were most important. Broad-sense heritability for all characters was high to medium (0.48-0.91), indicating that a high response to selection would be expected. Hybrids can improve cape gooseberry yield without impairing fruit quality.Leiva-Brondo, M.; Prohens Tomás, J.; Nuez Viñals, F. (2001). Genetic analysis indicate superiority of perfomance of cape goosberry (Physalis peruviana L.) hybrids. Journal of New Seeds. 3(3):71-84. doi:10.1300/J153v03n03_04718433Abak, K., Güler, H. Y., Sari, N., & Paksoy, M. (1994). EARLINESS AND YIELD OF PHYSALIS (P. IXOCARPA BROT. AND P. PERUVIANA L.) IN GREENHOUSE, LOW TUNNEL AND OPEN FIELD. Acta Horticulturae, (366), 301-306. doi:10.17660/actahortic.1994.366.37Kang, M. S. (1997). Using Genotype-by-Environment Interaction for Crop Cultivar Development. Advances in Agronomy Volume 62, 199-252. doi:10.1016/s0065-2113(08)60569-6Klinac, D. J. (1986). Cape gooseberry (Physalis peruviana) production systems. New Zealand Journal of Experimental Agriculture, 14(4), 425-430. doi:10.1080/03015521.1986.10423060Mather, K., & Jinks, J. L. (1977). Introduction to Biometrical Genetics. doi:10.1007/978-94-009-5787-9Mazer, S. J., & Schick, C. T. (1991). Constancy of population parameters for life history and floral traits in Raphanus sativus L. I. Norms of reaction and the nature of genotype by environment interactions. Heredity, 67(2), 143-156. doi:10.1038/hdy.1991.74Nyquist, W. E., & Baker, R. J. (1991). Estimation of heritability and prediction of selection response in plant populations. Critical Reviews in Plant Sciences, 10(3), 235-322. doi:10.1080/07352689109382313Pearcy, R. W. (1990). Sunflecks and Photosynthesis in Plant Canopies. Annual Review of Plant Physiology and Plant Molecular Biology, 41(1), 421-453. doi:10.1146/annurev.pp.41.060190.002225Péron, J. Y., Demaure, E., & Hannetel, C. (1989). POSSIBILITIES OF TROPICAL SOLANACEAE AND CUCURBITACEAE INTRODUCTION IN FRANCE. Acta Horticulturae, (242), 179-186. doi:10.17660/actahortic.1989.242.24Proctor, F. J. (1990). THE EUROPEAN COMMUNITY MARKET FOR TROPICAL FRUIT AND FACTORS LIMITING GROWTH. Acta Horticulturae, (269), 29-40. doi:10.17660/actahortic.1990.269.

Propositional update operators based on formula/literal dependence

International audienceWe present and study a general family of belief update operators in a propositional setting. Its operators are based on formula/literal dependence, which is more fine-grained than the notion of formula/variable dependence that was proposed in the literature: formula/variable dependence is a particular case of formula/literal dependence. Our update operators are defined according to the "forget-then-conjoin" scheme: updating a belief base by an input formula consists in first forgetting in the base every literal on which the input formula has a negative influence, and then conjoining the resulting base with the input formula. The operators of our family differ by the underlying notion of formula/literal dependence, which may be defined syntactically or semantically, and which may or may not exploit further information like known persistent literals and pre-set dependencies. We argue that this allows to handle the frame problem and the ramification problem in a more appropriate way. We evaluate the update operators of our family w.r.t. two important dimensions: the logical dimension, by checking the status of the Katsuno-Mendelzon postulates for update, and the computational dimension, by identifying the complexity of a number of decision problems (including model checking, consistency and inference), both in the general case and in some restricted cases, as well as by studying compactability issues. It follows that several operators of our family are interesting alternatives to previous belief update operators

Azimuthal Angle Correlations for Rapidity Separated Hadron Pairs in d+Au Collisions at sqrt(s_NN) = 200 GeV

We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at mid-rapidity in deuteron-gold (d+Au) and proton-proton (p+p) collisions at sqrt(s_NN) = 200 GeV. Jet structures are observed in the correlations which we quantify in terms of the conditional yield and angular width of away side partners. The kinematic region studied here samples partons in the gold nucleus carrying nucleon momentum fraction x~0.1 to x~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.Comment: 330 authors, 6 pages text, 4 figures, no tables. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Centrality dependence of charged hadron production in deuteron+gold and nucleon+gold collisions at sqrt(s_NN)=200 GeV

We present transverse momentum (p_T) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at \sqrts = 200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon was observed in one of two forward rapidity detectors. The spectra and yields were investigated as a function of the number of binary nucleon-nucleon collisions, \nu, suffered by deuteron nucleons. A comparison of charged particle yields to those in p+p collisions show that the yield per nucleon-nucleon collision saturates with \nu for high momentum particles. We also present the charged hadron to neutral pion ratios as a function of p_T.Comment: 330 authors, 15 pages text, 16 figures, 3 tables. Submitted to Phys. Rev. Lett. v2 has minor changes to reflect revisions during review process. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

High transverse momentum eta meson production in p+p, d+Au and Au+Au collisions at sqrt(s_NN) = 200 GeV

Inclusive transverse momentum spectra of eta mesons in the range p_T~2-12 GeV/c have been measured at mid-rapidity (|\eta| < 0,35) by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au collisions at sqrt(s_NN) = 200 GeV. The eta mesons are reconstructed through their eta--> \gamma\gamma channel for the three colliding systems as well as through the eta-->pi^0 pi+ pi- decay mode in p+p and d+Au collisions. The nuclear modification factor in d+Au collisions, R_dAu(p_T~1.0-1.1, suggests at most only modest p_T broadening ("Cronin enhancement"). In central Au+Au reactions, the eta yields are significantly suppressed, with R_AuAu(pT)~0.2. The ratio of eta to pi^0 yields is approximately constant as a function of p_T for the three colliding systems in agreement with the high-p_T world average of R_eta/pi^0 \approx 0.5 in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions for a wide range of center-of-mass energies [sqrt(s_NN)~3-1800 GeV] as well as, for high scaled momentum x_p, in e+e- annihilations at sqrt(s)=91.2 GeV. These results are consistent with a scenario where high-p_T eta production in nuclear collisions at RHIC is largely unaffected by initial-state effects, but where light-quark mesons (pi^0;eta) are equally suppressed due to final-state interactions of the parent partons in the dense medium produced in Au+Au reactions.Comment: 391 authors, NN pages text, RevTeX4, figures, tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Jet Structure from Dihadron Correlations in d+Au collisions at sqrt(s_NN) = 200 GeV

Dihadron correlations at high transverse momentum in d+Au collisions at sqrt(s_NN) = 200 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). From these correlations we extract several structural characteristics of jets; the root-mean-squared (RMS) transverse momentum of fragmenting hadrons with respect to the jet sqrt(), the mean sine-squared angle between the scattered partons , and the number of particles produced within the dijet that are associated with a high-p_T particle (dN/dx_E distributions). We observe that the fragmentation characteristics of jets in d+Au collisions are very similar to those in p+p collisions and that there is also little dependence on the centrality of the d+Au collision. This is consistent with the nuclear medium having little influence on the fragmentation process. Furthermore, there is no statistically significant increase in the value of from p+p to d+Au collisions. This constrains the amount of multiple scattering that partons undergo in the cold nuclear medium before and after a hard-collision.Comment: 330 authors, 30 pages text, RevTeX4, 42 figures, 20 tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm