A Self-Consistent First-Principles Technique Having Linear Scaling

An algorithm for first-principles electronic structure calculations having a computational cost which scales linearly with the system size is presented. Our method exploits the real-space localization of the density matrix, and in this respect it is related to the technique of Li, Nunes and Vanderbilt. The density matrix is expressed in terms of localized support functions, and a matrix of variational parameters, L, having a finite spatial range. The total energy is minimized with respect to both the support functions and the elements of the L matrix. The method is variational, and becomes exact as the ranges of the support functions and the L matrix are increased. We have tested the method on crystalline silicon systems containing up to 216 atoms, and we discuss some of these results.Comment: 12 pages, REVTeX, 2 figure

Towards a Linear-Scaling DFT Technique: The Density Matrix Approach

A recently proposed linear-scaling scheme for density-functional pseudopotential calculations is described in detail. The method is based on a formulation of density functional theory in which the ground state energy is determined by minimization with respect to the density matrix, subject to the condition that the eigenvalues of the latter lie in the range [0,1]. Linear-scaling behavior is achieved by requiring that the density matrix should vanish when the separation of its arguments exceeds a chosen cutoff. The limitation on the eigenvalue range is imposed by the method of Li, Nunes and Vanderbilt. The scheme is implemented by calculating all terms in the energy on a uniform real-space grid, and minimization is performed using the conjugate-gradient method. Tests on a 512-atom Si system show that the total energy converges rapidly as the range of the density matrix is increased. A discussion of the relation between the present method and other linear-scaling methods is given, and some problems that still require solution are indicated.Comment: REVTeX file, 27 pages with 4 uuencoded postscript figure

Basis Functions for Linear-Scaling First-Principles Calculations

In the framework of a recently reported linear-scaling method for density-functional-pseudopotential calculations, we investigate the use of localized basis functions for such work. We propose a basis set in which each local orbital is represented in terms of an array of `blip functions'' on the points of a grid. We analyze the relation between blip-function basis sets and the plane-wave basis used in standard pseudopotential methods, derive criteria for the approximate equivalence of the two, and describe practical tests of these criteria. Techniques are presented for using blip-function basis sets in linear-scaling calculations, and numerical tests of these techniques are reported for Si crystal using both local and non-local pseudopotentials. We find rapid convergence of the total energy to the values given by standard plane-wave calculations as the radius of the linear-scaling localized orbitals is increased.Comment: revtex file, with two encapsulated postscript figures, uses epsf.sty, submitted to Phys. Rev.

Avaliação do conhecimento e percepção dos profissionais da estratégia de saúde da família sobre o uso de plantas medicinais e fitoterapia em Petrolina-PE, Brasil.

RESUMO Este trabalho objetivou verificar se os profissionais de nível superior, ligados a Estratégia de Saúde da Família (ESF) do Município de Petrolina-PE percebem a importância, utilização e indicações de Plantas Medicinais e Fitoterápicos. Trata-se de um estudo transversal de caráter exploratório e descritivo, no qual participaram 96 profissionais de nível superior locados em Unidades da ESF. Os dados foram obtidos através de entrevista individual utilizando questionário semiestruturado. Para análise estatística, foi utilizado o teste Pearson Qui quadrado. As plantas medicinais mais citadas foram o Boldo (Plectranthus barbatus A.) e a Camomila (Matricaria recutita L.). Os fitoterápicos foram indicados apenas por 5 (5,2%) médicos e os mais citados foram Guaco® e Maracugina®. 36 (37,5%) dos profissionais acham que não estão preparados para repassar as informações sobre o uso de plantas medicinais e apenas 35 (36,5%) se sentem preparados para prescrever fitoterápicos. Observa-se a necessidade de capacitação e motivação desses profissionais para a utilização correta e segura das Plantas Medicinais e Fitoterapia

The use of medicinal plants by an indigenous Pataxó community in NE Brazil O uso de plantas medicinais por uma comunidade indígena Pataxó no NE do Brasil

We identified and classified 48 medicinal plants used by the Pataxó Indians in south Bahia, Brazil. The location is an ecologically threatened area designated by UNESCO as a World Heritage Site. The aim of this paper is to document phytotherapeutic practices in the indigenous community of Mata Medonha. We conducted interviews with the 25 families present at the area. Of the 48 medicinal species identified, only 14 (29%) had been examined for mechanism of action or isolation of biochemical compounds, according to bibliographic research. The plants were deposited at the Alexandre Leal Costa Herbarium of the Federal University of Bahia. We gathered information about the preparation and uses of the plants. The species are used for a variety of maladies, including flu, congestion, bronchitis and headaches, pain, snake bites, and some were only used for women's disorders. The Pataxó ethnopharmacological knowledge is under pressure from the economic outmigration of the community and threats to the biodiversity from logging, mining, and tourism. The plants studied here include important drug candidates. Additional research on the molecular aspects of the species cited should be performed.<br>Foram identificadas e classificadas 48 plantas medicinais usadas por Índios Pataxós no sul da Bahia. A região é área de risco ecológico designada pela UNESCO como Sítio do Patrimônio Mundial. O objetivo deste estudo foi de documentar as práticas fitoterápicas na comunidade indígena da Mata Medonha. Foram conduzidas entrevistas com as 25 famílias presentes no local. Dentre as 48 espécies identificadas, apenas 14 (29%) foram avaliadas quanto ao mecanismo de ação ou isolamento de compostos químicos, de acordo com levantamento bibliográfico. As plantas foram depositadas no Herbário Alexandre Leal Costa da Universidade Federal da Bahia. Foram registradas informações sobre o preparo e uso das plantas citadas. As espécies são usadas para uma variedade de doenças incluindo gripe, congestão, bronquite, dores em geral, picadas de cobra e algumas apenas para doenças femininas. O conhecimento etnofarmacológico Pataxó está sobre pressão pelas migrações para fora da comuindade e ameaças à biodiversidade por desmatamento, mineração e turismo. As plantas estudadas incluem importantes candidatos a fármacos. Pesquisas adicionais sobre os aspectos moleculares devem ser realizadas

Results on total and elastic cross sections in proton–proton collisions at √s=200 GeV

We report results on the total and elastic cross sections in proton-proton collisions at √s = 200 GeV obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section was measured in the squared four-momentum transfer range 0.045 ≤ −t ≤ 0.135 GeV2. The value of the exponential slope parameter B of the elastic differential cross section dσ/dt ∼ e−Bt in the measured −t range was found to be B = 14.32 ± 0.09(stat.)+0.13 −0.28(syst.) GeV−2. The total cross section σtot, obtained from extrapolation of the dσ/dt to the optical point at −t = 0, is σtot = 54.67 ± 0.21(stat.)+1.28 −1.38(syst.) mb. We also present the values of the elastic cross section σel = 10.85 ± 0.03(stat.)+0..49 −0.41(syst.) mb, the elastic cross section integrated within the STAR t-range σ det el = 4.05 ± 0.01(stat.)+0.18−0.17(syst.) mb, and the inelastic cross section σinel = 43.82 ± 0.21(stat.)+1.37−1.44(syst.) mb. The results are compared with the world dat

Measurement of groomed jet substructure observables in p+p collisions at √s=200 GeV with STAR

In this letter, measurements of the shared momentum fraction (zg) and the groomed jet radius (Rg), as defined in the SoftDrop algorithm, are reported in p+p collisions at √s = 200 GeV collected by the STAR experiment. These substructure observables are differentially measured for jets of varying resolution parameters from R = 0.2 − 0.6 in the transverse momentum range 15 < pT,jet < 60 GeV/c. These studies show that, in the pT,jet range accessible at √s = 200 GeV and with increasing jet resolution parameter and jet transverse momentum, the zg distribution asymptotically converges to the DGLAP splitting kernel for a quark radiating a gluon. The groomed jet radius measurements reflect a momentum-dependent narrowing of the jet structure for jets of a given resolution parameter, i.e., the larger the pT,jet, the narrower the first splitting. For the first time, these fully corrected measurements are compared to Monte Carlo generators with leading order QCD matrix elements and leading log in the parton shower, and to state-of-the-art theoretical calculations at next-to-leading-log accuracy. We observe that PYTHIA 6 with parameters tuned to reproduce RHIC measurements is able to quantitatively describe data, whereas PYTHIA 8 and HERWIG 7, tuned to reproduce LHC data, are unable to provide a simultaneous description of both zg and Rg, resulting in opportunities for fine parameter tuning of these models for p+p collisions at RHIC energies. We also find that the theoretical calculations without non-perturbative corrections are able to qualitatively describe the trend in data for jets of large resolution parameters at high pT,jet, but fail at small jet resolution parameters and low jet transverse momenta

Investigation of the linear and mode-coupled flow harmonics in Au+Au collisions at √sNN = 200 GeV

Flow harmonics (vn) of the Fourier expansion for the azimuthal distributions of hadrons are commonly employed to quantify the azimuthal anisotropy of particle production relative to the collision symmetry planes. While lower order Fourier coefficients (v2 and v3) are more directly related to the corresponding eccentricities of the initial state, the higher-order flow harmonics (vn>3) can be induced by a modecoupled response to the lower-order anisotropies, in addition to a linear response to the same-order anisotropies. These higher-order flow harmonics and their linear and mode-coupled contributions can be used to more precisely constrain the initial conditions and the transport properties of the medium in theoretical models. The multiparticle azimuthal cumulant method is used to measure the linear and mode-coupled contributions in the higher-order anisotropic flow, the mode-coupled response coefficients, and the correlations of the event plane angles for charged particles as functions of centrality and transverse momentum in Au+Au collisions at nucleon-nucleon center-of-mass energy √sN N= 200 GeV. The results are compared to similar LHC measurements as well as to several viscous hydrodynamic calculations with varying initial conditions

Measurement of cold nuclear matter effects for inclusive J/ψ in p+Au collisions at √sNN = 200 GeV

Measurement by the STAR experiment at RHIC of the cold nuclear matter (CNM) effects experienced by inclusive J/ψ at mid-rapidity in 0-100% p+Au collisions at √sNN = 200 GeV is presented. Such effects are quantified utilizing the nuclear modification factor, RpAu, obtained by taking a ratio of J/ψ yield in p+Au collisions to that in p+p collisions scaled by the number of binary nucleon-nucleon collisions. The differential J/ψ yield in both p+p and p+Au collisions is measured through the dimuon decay channel, taking advantage of the trigger capability provided by the Muon Telescope Detector in the RHIC 2015 run. Consequently, the J/ψ RpAu is derived within the transverse momentum (pT) range of 0 to 10 GeV/c. A suppression of approximately 30% is observed for pT < 2 GeV/c, while J/ψ RpAu becomes compatible with unity for pT greater than 3 GeV/c, indicating the J/ψ yield is minimally affected by the CNM effects at high pT. Comparison to a similar measurement from 0-20% central Au+Au collisions reveals that the observed strong J/ψ suppression above 3 GeV/c is mostly due to the hot medium effects, providing strong evidence for the formation of the quark-gluon plasma in these collisions. Several model calculations show qualitative agreement with the measured J/ψ RpAu, while their agreement with the J/ψ yields in p+p and p+Au collisions is worse