8,932 research outputs found
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
Molecular and Metabolic Analyses in Developing Olive Fruit in Relationto Different Water Regimes
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 --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 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 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 , we also prove a super-Arrhenius scaling of the form
. For FA1f in = we
rigorously prove the power law scalings recently derived in \cite{JMS} while in
we obtain upper and lower bounds consistent with findings therein.
Our results are based on a novel multi-scale approach which allows to analyze
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 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 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 biolĂłgico de Meloidogyne spp. com fungos nematĂłfagos em cultivo de cenoura.
A cenoura Ă© uma hortaliça do grupo das raĂzes tuberosas, cultivada em larga escala em vĂĄrios estados brasileiros. Dentre os problemas fitossanitĂĄrios associados Ă cultura destacam-se os nematoides galhadores do gĂȘnero Meloidogyne, cujas infestaçÔes podem acarretar em atĂ© 100% de perda da produção. A busca por alternativas ao controle quĂmico tem se intensificado nos Ășltimos anos, com o advento de bionematicidas, especialmente os formulados Ă base de fungos nematĂłfagos. Assim, o objetivo desse estudo foi comparar a eficiĂȘncia da aplicação dos fungos Paecilomyces lilacinus e Pochonia chlamydosporia em comparação ao uso do controle quĂmico, em plantio de cenoura sob infestação de nematoide-das-galhas. O estudo foi conduzido no Instituto Taquaritinguense de Ensino Superior (ITES), Taquaritinga, SP, em condiçÔes de campo, utilizando a cenoura hĂbrida var. ?Sirkana?. O delineamento experimental foi em blocos ao acaso (DBC) com cinco repetiçÔes e seis tratamentos: 1. P. lilacinus; 2. P. chlamydosporia; 3. P. lilacinus + P. chlamydosporia; 4. Adicarbe; 5. CadusafĂłs e 6. Testemunha (sem aplicação). As doses dos respectivos tratamentos constaram de 0,67 L/m2 de canteiro com substrato colonizado pelos fungos nematĂłfagos, 30 kg/ha de p.c. de Aldicarbe e 25 kg/ha de p.c. de CadusafĂłs. Pelos resultados obtidos, os fungos nematĂłfagos P. lilacinus e P. chlamydosporia podem ser recomendados no controle de nematoides-das-galhas em cultivo de cenoura, como alternativa ao controle quĂmico. 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, SĂŁo 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 âarilâ 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 CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPnĂŁo temnĂŁo temnĂŁo te
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