1,602 research outputs found

    Non-perturbative effects in the BMN limit of N=4 supersymmetric Yang-Mills

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    One-instanton contributions to the correlation functions of two gauge-invariant single-trace operators in N=4 SU(N) Yang-Mills theory are studied in semi-classical approximation in the BMN limit. The most straightforward examples involve operators with four bosonic impurities. The explicit form for the correlation functions, which determine the anomalous dimensions, follows after integration over the large number of bosonic and fermionic moduli. Our results demonstrate that the instanton contributions scale appropriately in the BMN limit. We find impressive agreement with the D-instanton contributions to mass matrix elements of the dual plane-wave IIB superstring theory, obtained in a previous paper. Not only does the dependence on the scaled coupling constants match, but the dependence on the mode numbers of the states is also in striking agreement.Comment: 52 pages, no figures, latex; V2: minor change

    Provenance for SPARQL queries

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    Determining trust of data available in the Semantic Web is fundamental for applications and users, in particular for linked open data obtained from SPARQL endpoints. There exist several proposals in the literature to annotate SPARQL query results with values from abstract models, adapting the seminal works on provenance for annotated relational databases. We provide an approach capable of providing provenance information for a large and significant fragment of SPARQL 1.1, including for the first time the major non-monotonic constructs under multiset semantics. The approach is based on the translation of SPARQL into relational queries over annotated relations with values of the most general m-semiring, and in this way also refuting a claim in the literature that the OPTIONAL construct of SPARQL cannot be captured appropriately with the known abstract models.Comment: 22 pages, extended version of the ISWC 2012 paper including proof

    Investigating the Effect of Ozone on the Biodegradability of Distillery Wastewater

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    The effect of ozonation on wine distillery wastewater was investigated firstly by monitoring the effect of ozonationon the composition of the wastewater and, secondly, by investigating its effect on the biodegradability of thewastewater. An average COD reduction of 271 mg COD.g O3-1 was found for wastewater from a distillery pondsystem. Stable microbial populations, which are found in upflow anaerobic sludge blanket (UASB) granules, wereused to determine the toxic effect of wastewater on microbial activity. Granule activity was measured in terms ofthe rate of biogas and methane production, as well as cumulative biogas volume. Low ozone doses (200 to 400 mgO3.L-1) increased granule activity in terms of biogas, methane production, and cumulative gas volumes. Distillerywastewater reduced the activity of granules, most likely due to the presence of polyphenols and other recalcitrantcompounds in the distillery wastewater

    Factors associated with anaemia status and haemoglobin concentrations in infants 6-11 months in Mbala District, Northern Province, Zambia

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    This paper presents information on the factors associated with anaemia status and haemoglobin concentrations in infants 6-11 months old in Mbala District, Northern Province, Zambia. The information is drawn from the baseline data collection of a study involving 631 caregiver-child pairs. The data presented here includes anthropometry, malaria parasitism, concentrations of haemoglobin (Hb) and serum transferrin receptor (STfR), and information on household characteristics, infant and young child feeding (IYCF) practices, and morbidity, gathered via questionnaire. It was found that 57% of the sample was anaemic (Hb < 110 g/L), 93% was iron deficient (STfR > 8.3 mg/L) and 53% had iron deficiency anaemia. Overall, 30% of the infants in the sample were stunted, 2% were wasted, and 16% were underweight, and 22%, 56% and 18% of infants were meeting minimum dietary diversity, minimum meal frequency, and minimum acceptable diet, respectively, and 28% consumed iron rich foods in the previous 24 hours. Infants who had achieved a minimum dietary diversity score (OR = 0.44; 95% CI: 0.30-0.65), who had consumed iron rich foods in the previous 24 hours (OR = 0.56; 95% CI: 0.40-0.80), or were female (OR = 0.69; 95% CI: 0.50-0.94), had significantly lower risks of being anaemic. Infants that tested positive for malaria parasitism (OR = 4.33; 95% CI: 2.16- 8.70), as well as those having a fever (OR = 1.88; 95% CI: 1.36-2.59) in the previous two weeks had significantly greater odds of being anaemic. Despite these associations, whether or not a child slept under a mosquito net was not related to their risk of being anaemic. Infants in households that treated their water to make it safer to consume had average haemoglobin concentrations 3 g/L higher than those who did not (p = 0.021), but this did not translate into a significant difference in the odds of being anaemic. These results shed light on the specific causes of anaemia in the Zambian context, and illustrate the importance of improving dietary quality, specifically the intake of iron, and reducing the prevalence of diseases including malaria in order to reduce the prevalence of anaemia.Keywords: Nutritional status, Zambia, anaemia, iron deficiency, malaria, serum transferrin receptor, haemoglobi

    On Signatures of Twisted Magnetic Flux Tube Emergence

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    Recent studies of NOAA active region 10953, by Okamoto {\it et al.} ({\it Astrophys. J. Lett.} {\bf 673}, 215, 2008; {\it Astrophys. J.} {\bf 697}, 913, 2009), have interpreted photospheric observations of changing widths of the polarities and reversal of the horizontal magnetic field component as signatures of the emergence of a twisted flux tube within the active region and along its internal polarity inversion line (PIL). A filament is observed along the PIL and the active region is assumed to have an arcade structure. To investigate this scenario, MacTaggart and Hood ({\it Astrophys. J. Lett.} {\bf 716}, 219, 2010) constructed a dynamic flux emergence model of a twisted cylinder emerging into an overlying arcade. The photospheric signatures observed by Okamoto {\it et al.} (2008, 2009) are present in the model although their underlying physical mechanisms differ. The model also produces two additional signatures that can be verified by the observations. The first is an increase in the unsigned magnetic flux in the photosphere at either side of the PIL. The second is the behaviour of characteristic photospheric flow profiles associated with twisted flux tube emergence. We look for these two signatures in AR 10953 and find negative results for the emergence of a twisted flux tube along the PIL. Instead, we interpret the photospheric behaviour along the PIL to be indicative of photospheric magnetic cancellation driven by flows from the dominant sunspot. Although we argue against flux emergence within this particular region, the work demonstrates the important relationship between theory and observations for the successful discovery and interpretation of signatures of flux emergence.Comment: 14 pages, 8 figures, accepted for publication in Solar Physic

    Dynamic Provenance for SPARQL Update

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    While the Semantic Web currently can exhibit provenance information by using the W3C PROV standards, there is a "missing link" in connecting PROV to storing and querying for dynamic changes to RDF graphs using SPARQL. Solving this problem would be required for such clear use-cases as the creation of version control systems for RDF. While some provenance models and annotation techniques for storing and querying provenance data originally developed with databases or workflows in mind transfer readily to RDF and SPARQL, these techniques do not readily adapt to describing changes in dynamic RDF datasets over time. In this paper we explore how to adapt the dynamic copy-paste provenance model of Buneman et al. [2] to RDF datasets that change over time in response to SPARQL updates, how to represent the resulting provenance records themselves as RDF in a manner compatible with W3C PROV, and how the provenance information can be defined by reinterpreting SPARQL updates. The primary contribution of this paper is a semantic framework that enables the semantics of SPARQL Update to be used as the basis for a 'cut-and-paste' provenance model in a principled manner.Comment: Pre-publication version of ISWC 2014 pape

    Instanton calculus in R-R background and the topological string

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    We study a system of fractional D3 and D(-1) branes in a Ramond-Ramond closed string background and show that it describes the gauge instantons of N=2 super Yang-Mills theory and their interactions with the graviphoton of N=2 supergravity. In particular, we analyze the instanton moduli space using string theory methods and compute the prepotential of the effective gauge theory exploiting the localization methods of the instanton calculus showing that this leads to the same information given by the topological string. We also comment on the relation between our approach and the so-called Omega-background.Comment: 38 pages, 2 figures, JHEP class (included); final version to be pubished in JHE

    Instanton effects in N=1 brane models and the Kahler metric of twisted matter

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    We consider locally consistent systems of magnetized D9 branes on an orbifolded six-torus which support N=1 gauge theories. In such realizations, the matter multiplets arise from "twisted" strings connecting different stacks of branes. The introduction of Euclidean 5 branes (E5) wrapped on the six-dimensional compact space leads to instanton effects. For instance, if the system is engineered so as to yield SQCD, a single E5 brane may account for the ADS/TVY superpotential. We discuss the subtle interplay that exists between the annuli diagrams with an E5 boundary and the holomorphicity properties of the effective low-energy action of the N=1 theory. The consistency of this picture allows to obtain information on the Kahler metric of the chiral matter multiplets arising from twisted strings.Comment: 33 pages, 4 figures. V2: improved discussion, clarifyng comments and references added. Version to be published in JHE

    N=4 super Yang-Mills matrix integrals for almost all simple gauge groups

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    In this paper the partition function of N=4 D=0 super Yang-Mills matrix theory with arbitrary simple gauge group is discussed. We explicitly computed its value for all classical groups of rank up to 11 and for the exceptional groups G_2, F_4 and E_6. In the case of classical groups of arbitrary rank we conjecture general formulas for the B_r, C_r and D_r series in addition to the known result for the A_r series. Also, the relevant boundary term contributing to the Witten index of the corresponding supersymmetric quantum mechanics has been explicitly computed as a simple function of rank for the orthogonal and symplectic groups SO(2N+1), Sp(2N), SO(2N).Comment: Latex2e, 21pp; v2: minor corrections, references adde

    Iron-fortified foods are needed to meet the Estimated Average Requirement for iron in Australian infants 6-12 months

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    OnlinePublBackground: Meeting iron intake recommendations is challenging for infants 6–12 mo, especially breastfed infants. Three-quarters of Australian infants 6–12 mo have iron intakes below the estimated average requirement (7 mg), placing them at risk of iron deficiency. After 6 mo, breastmilk is no longer sufficient to meet the increased demand for iron, and iron-rich complementary foods are recommended. Ironfortified foods may be a means of improving iron intake in infants, particularly those that are breastfed. Objectives: The aims of the study were as follows: 1) to examine the effect of milk-type and fortified foods on iron intake and the prevalence of inadequacy in infants 6–12 mo; 2) to model the effect of fixed amounts of iron-fortified infant cereal (IFIC) at 6 levels of iron fortification on total iron intake and the prevalence of inadequacy; and 3) to assess the effect IFIC on the intake of other nutrients in the diet. Design: Secondary analysis of cross-sectional dietary intake data of infants 6–12 mo (n ÂŒ 286) participating in the Australian Feeding Infants and Toddlers Study (OzFITS) 2021. Results: Median (interquartile range) iron intake was 8.9 (7.5, 10.3); 6.3 (4.5, 8.2); and 2.7 (1.5, 4.4) mg/d in formula-fed, combinationfed, and breastfed infants, respectively. The corresponding prevalence of inadequacy was 19%, 67%, and 96%. Infants who consumed fortified foods had higher median iron intakes than those who did not, 6.2 compared with 1.9 mg/d. Dietary modeling showed that consuming 18 g (300 kJ) of IFIC, fortified at 35 mg/100 g dry weight, reduces the prevalence of inadequacy for iron from 75% to 5% for all infants. Conclusions: Iron intakes are low in Australian infants, especially for breastfed infants in the second half of infancy. Modeling shows that 300 kJ of IFIC, the current manufacturer-recommended serving, fortified at 35 mg/100 g dry weight, added to infant diets would be an effective means to reduce the prevalence of inadequacy for iron.Najma A. Moumin, Jessica A. Grieger, Merryn J. Netting, Maria Makrides, Tim J. Gree
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