Lattice computation of structure functions

Recent lattice calculations of hadron structure functions are described.Comment: Plenary talk presented at LATTICE96, LaTeX, 7 pages, 5 figures, espcrc2.sty and epsfig.sty include

Metabolomics approach to studying minimally processed peach (Prunus persica) fruit

Fresh-cut fruit products for both retail and food service applications have increasingly appeared in the market place in recent years. Among different fruit types, peaches can be used and are highly appreciated as fresh-cut product although their commercial success is limited due to their short shelf-life and the quick onset of wounding-related physiological reactions. In this work we analyzed the technological and physiological changes induced by fresh-cut preparation in three different types of peach cultivars: 'Fayette' (melting), 'Wilhelmina' (non-melting) and 'Ghiaccio3' (stony hard). We performed a metabolite targeting profiling to focus on the changes in organic acid levels, important components of fruit taste and organoleptic quality of peaches. Interestingly, 'Ghiaccio3' showed an increase of several organic acids after cutting while 'Fayette' and 'Wilhelmina' showed unchanged amounts or a general reduction. Cutting induces a similar pattern of change in important metabolites (i.e., dehydroascorbate, alanine) in all the three peach types while other metabolites (i.e., citric acid) appeared to be differentially regulated in the considered peach cultivars

Correlated trends of coexisting magnetism and superconductivity in optimally electron-doped oxy-pnictides

We report on the recovery of the short-range static magnetic order and on the concomitant degradation of the superconducting state in optimally F-doped SmFe_(1-x)Ru_(x)AsO_0.85F_0.15 for 0.1< x<0.6. The two reduced order parameters coexist within nanometer-size domains in the FeAs layers and finally disappear around a common critical threshold x_c=0.6. Superconductivity and magnetism are shown to be closely related to two distinct well-defined local electronic environments of the FeAs layers. The two transition temperatures, controlled by the isoelectronic and diamagnetic Ru substitution, scale with the volume fraction of the corresponding environments. This fact indicates that superconductivity is assisted by magnetic fluctuations, which are frozen whenever a short-range static order appears, and totally vanish above the magnetic dilution threshold x_c.Comment: Approved for publication in Phys. Rev. Letter

Non-perturbative quark mass renormalization

We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\Lambda$--parameter in this theory with completely controlled errors.Comment: Talk given at LATTICE '97, 6 pages, Latex source, 7 eps figures, needs epsfi

Relaxation times of kinetically constrained spin models with glassy dynamics

We analyze the density and size dependence of the relaxation time $\tau$ for kinetically constrained spin systems. These have been proposed as models for strong or fragile glasses and for systems undergoing jamming transitions. For the one (FA1f) or two (FA2f) spin facilitated Fredrickson-Andersen model at any density $\rho<1$ and for the Knight model below the critical density at which the glass transition occurs, we show that the persistence and the spin-spin time auto-correlation functions decay exponentially. This excludes the stretched exponential relaxation which was derived by numerical simulations. For FA2f in $d\geq 2$, we also prove a super-Arrhenius scaling of the form $\exp(1/(1-\rho))\leq \tau\leq\exp(1/(1-\rho)^2)$. For FA1f in $d$=$1,2$ we rigorously prove the power law scalings recently derived in \cite{JMS} while in $d\geq 3$ we obtain upper and lower bounds consistent with findings therein. Our results are based on a novel multi-scale approach which allows to analyze $\tau$ in presence of kinetic constraints and to connect time-scales and dynamical heterogeneities. The techniques are flexible enough to allow a variety of constraints and can also be applied to conservative stochastic lattice gases in presence of kinetic constraints.Comment: 4 page

First results with non-perturbative fermion improvement

We present initial results for light hadron masses and nucleon structure functions using a recent proposal for eliminating all $O(a)$ effects from Wilson fermion simulations in the quenched approximation. With initially limited statistics, we find a much more linear APE plot and a value of the axial coupling $g_A$ nearer to the experimental point than with comparable runs using unimproved Wilson fermions.Comment: 3 pages, 2 PostScript figures, LaTeX 2.09 with espcrc2.sty v2.6, amstex and epsf, talk presented at LATTICE96(phenomenology) by P. Stephenso

Controle biológico de Meloidogyne spp. com fungos nematófagos em cultivo de cenoura.

A cenoura é uma hortaliça do grupo das raízes tuberosas, cultivada em larga escala em vários estados brasileiros. Dentre os problemas fitossanitários associados à cultura destacam-se os nematoides galhadores do gênero Meloidogyne, cujas infestações podem acarretar em até 100% de perda da produção. A busca por alternativas ao controle químico tem se intensificado nos últimos anos, com o advento de bionematicidas, especialmente os formulados à base de fungos nematófagos. Assim, o objetivo desse estudo foi comparar a eficiência da aplicação dos fungos Paecilomyces lilacinus e Pochonia chlamydosporia em comparação ao uso do controle químico, em plantio de cenoura sob infestação de nematoide-das-galhas. O estudo foi conduzido no Instituto Taquaritinguense de Ensino Superior (ITES), Taquaritinga, SP, em condições de campo, utilizando a cenoura híbrida var. ?Sirkana?. O delineamento experimental foi em blocos ao acaso (DBC) com cinco repetições e seis tratamentos: 1. P. lilacinus; 2. P. chlamydosporia; 3. P. lilacinus + P. chlamydosporia; 4. Adicarbe; 5. Cadusafós e 6. Testemunha (sem aplicação). As doses dos respectivos tratamentos constaram de 0,67 L/m2 de canteiro com substrato colonizado pelos fungos nematófagos, 30 kg/ha de p.c. de Aldicarbe e 25 kg/ha de p.c. de Cadusafós. Pelos resultados obtidos, os fungos nematófagos P. lilacinus e P. chlamydosporia podem ser recomendados no controle de nematoides-das-galhas em cultivo de cenoura, como alternativa ao controle químico. The carrot is a vegetable of the tuberous roots group, cultivated on a large scale in several Brazilian states. Among the phytosanitary problems associated with the crop, galling nematodes of the genus Meloidogyne stand out, whose infestations can lead to up to 100% loss of production. The search for alternatives to chemical control has intensified in recent years with the advent of bionematicides, especially those formulated based on nematophagous fungi. Thus, the aim of this study was to compare the efficiency of the application of the fungi Paecilomyces lilacinus, and Pochonia chlamydosporia compared to the use of chemical control, in carrot planting under root-knot nematode infestation. The study was carried out at Instituto Taquaritinguense de Ensino Superior (ITES), municipality of Taquaritinga, São Paulo state, Brazil under field conditions, using the hybrid carrot var. 'Sirkana'. The experimental design was in complete randomized blocks with five replications and six treatments: 1. P. lilacinus; 2. P. chlamydosporia; 3. P. lilacinus + P. chlamydosporia; 4. Adicarb; 5. Cadusaphos and 6. Check Treatment (not applicable). The doses of the respective treatments consisted of 0.67 L/m2 of planting bed with substrate colonized by nematophagous fungi, 30 kg/ha of p.c. of Aldicarb, and 25 kg/ha of p.c. of Cadusaphos. Based on the results obtained, the nematophagous fungi P. lilacinus and P. chlamydosporia can be recommended for the control of root-knot nematodes in carrot cultivation, as an alternative to chemical control

Non-perturbative improvement and renormalization of lattice operators

The Alpha Collaboration has proposed an optimal value for c_SW in the Sheikholeslami-Wohlert action, chosen to remove O(a) effects. To measure hadronic matrix elements to the same accuracy we need a method of finding O(a) improved operators, and their renormalization constants. We determine the Z factors by a non-perturbative method, measuring the matrix elements for single quark states propagating through gauge fields in the Landau gauge. The data show large effects coming from chiral symmetry breaking. This allows us to find the improvement coefficients too, by requiring that the amount of chiral symmetry breaking agrees with that predicted by the chiral Ward identities.Comment: 3 pages, Latex, 2 figures, epsf.sty and espcrc2.sty needed. Talk given at Lattice9

Perspectives for a framework to understand aril initiation and development

A differentiated structure called “aril” has been described in seeds of several plant species during the course of evolution and might be considered as a supernumerary integument. Besides its ecological function in seed dispersal, the structure also represents a relevant character for systematic classification and exhibits important properties that impart agronomic value in certain species. Little is known about the molecular pathways underlying this morphological innovation because it is absent in currently used model species. A remarkable feature of the seeds of Passiflora species is the presence of a conspicuous aril. This genus is known for the ornamental, medicinal, and food values of its species. In view of the molecular resources and tools available for some Passiflora species, we highlight the potential of these species as models for developmental studies of the aril7CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPnão temnão temnão te