Dynamic screening and energy loss of antiprotons colliding with excited Al clusters

We use time-dependent density functional theory to calculate the energy loss of an antiproton colliding with a small Al cluster previously excited. The velocity of the antiproton is such that non-linear effects in the electronic response of the Al cluster are relevant. We obtain that an antiproton penetrating an excited cluster transfers less energy to the cluster than an antiproton penetrating a ground state cluster. We quantify this difference and analyze it in terms of the cluster excitation spectrum.Comment: 23 pages, 4 figures, to be published in Nuclear Instruments and Methods B as a proceeding of the IISC-19 Workshop on Inelastic Ion-Surface Collision

Direct resolution of unoccupied states in solids via two photon photoemission

Non-linear effects in photoemission are shown to open a new access to the band structure of unoccupied states in solids, totally different from hitherto used photoemission spectroscopy. Despite its second-order nature, strong resonant transitions occur, obeying exact selection rules of energy, crystal symmetry, and momentum. Ab-initio calculations are used to demonstrate that such structures are present in low-energy laser spectroscopy experimental measurements on Si previously published. Similar resonances are expected in ultraviolet angle-resolved photoemission spectra, as shown in a model calculation on Al.Comment: 12 pages, including 4 figure

Dynamic screening of a localized hole during photoemission from a metal cluster

Recent advances in attosecond spectroscopy techniques have fueled the interest in the theoretical description of electronic processes taking place in the subfemtosecond time scale. Here we study the coupled dynamic screening of a localized hole and a photoelectron emitted from a metal cluster using a semi-classical model. Electron density dynamics in the cluster is calculated with Time-Dependent Density Functional Theory and the motion of the photoemitted electron is described classically. We show that the dynamic screening of the hole by the cluster electrons affects the motion of the photoemitted electron. At the very beginning of its trajectory, the photoemitted electron interacts with the cluster electrons that pile up to screen the hole. Within our model, this gives rise to a significant reduction of the energy lost by the photoelectron. Thus, this is a velocity dependent effect that should be accounted for when calculating the average losses suffered by photoemitted electrons in metals.Comment: 15 pages, 5 figure

In vitro effect of comercial pesticides on Trichoderma harzianum strain A- 34

El trabajo tuvo como objetivo evaluar el efecto in vitro de seis plaguicidas comerciales sobre el crecimiento micelial, la esporulación y la germinación de los conidios de Trichoderma harzianum cepa A-34. El ensayo fue llevado a cabo con los siguientes productos: folpet (Folpam 80 PH), mancozeb (Mancozeb 75 PH) y zineb (Zineb 80 PH), así como de tres insecticidas: cipermetrina (Cipermetrina 10 EC), lambda cialotrina (Karate 5 EC) y abamectina (Abamectina 1,8 EC) a las concentraciones de 10, 100, 200, 500, 1000 y 2000 mg L-1. Fue evaluada la inhibición del crecimiento micelial de la colonia del hongo y la acción sobre la producción y la germinación de los conidios. Los plaguicidas fueron clasificados por su toxicidad sobre el antagonista de acuerdo con la escala de la OILB y por su compatibilidad según el valor T. Los tres fungicidas folpet, mancozeb y zineb tienen efecto inhibitorio sobre el crecimiento del micelio del hongo T. harzianum al igual que abamectina y son clasificados como ligeramente tóxicos. Sin embargo al considerar el valor T se clasifica a zineb, como muy tóxico, y a mancozeb y folpet como moderadamente tóxicos, mientras que los insecticidas resultaron no tóxicos. Los fungicidas afectan la germinación de los conidios del antagonista pero los insecticidas no.The work aims to evaluate the in vitro effect of six commercial pesticides on the mycelia growth, the spore production and conidia germination of Trichoderma harzianum strain A-34. The assay was carried out with the following products: folpet (Folpam 80 PH), zineb (Zineb 80 PH), mancozeb (Mancozeb 75 PH), cipermetrina (Cipermetrina 10 EC), lambda cialotrina (Karate 5 EC) and abamectina (Abamectin 1.8 EC) to the concentrations of 10, 100, 200, 500, 1000 and 2000 mg L-1. The growth inhibition of the fungus colony, the effect of the pesticides on the spore production and the conidia germination were evaluated. The pesticides were classified according to their toxicity on the antagonist by the OILB scale and their compatibility according to the T value. The folpet, mancozeb and zineb fungicides, and the abamectina insecticide have inhibitory effect on the growth of the mycelia of the fungus T. harzianum, and they are classified as lightly toxic. However, when considering the T value, zineb is classified as very toxic, and mancozeb and folpet as moderately toxic, while the insecticides are not toxic to the antagonist. Fungicides affect the germination of the antagonist's conidia but insecticides do not.Fil: Castellanos González, Leónides . Universidad de Cienfuegos (Cuba)Fil: Lorenzo Nicao, María E.. Cienfuegos (Cuba). Laboratorio Provincial de Sanidad Vegetal Cienfuegos.Fil: Lina Muiño, Berta. Instituto de Investigación de Sanidad Vegetal (La Habana, Cuba)Fil: Hernández Pérez, Ricardo. Centro Agrobiotecnológico (México)Fil: Guillen Sánchez, Dagoberto. Universidad Autónoma del Estado de Morelos (México). Escuela de Estudios Superiores de Xalosto

Bienestar animal de corderos ternascos durante su espera en matadero

El presente trabajo consistió en valorar la respuesta de estrés al que son sometidos los corderos desde que llegan al matadero hasta su sacrificio en distintas épocas del año, primavera y verano. Se tomaron muestras de sangre durante el sacrificio del animal para la valoración de diferentes parámetros sanguíneos de respuesta de estrés y tras el faenado se valoró la calidad de la canal y de la carne de los corderos. Se encontraron diferencias significativas con mayores valores para los corderos sacrificados en verano en el número de linfocitos, lactato deshidrogenasa (LDH), cortisol y pHs y menores en el número de leucocitos, neutrófilos, relación neutrófilos/linfocitos, volumen corpuscular medio, concentración de glucosa y rendimiento de la canal. Los corderos sacrificados en verano tuvieron más comprometido su nivel de bienestar por el mayor nivel de cortisol y LDH junto con unos pHs más elevados, lo que hace que la calidad de la carne sea inferior a los sacrificados en primavera

Orchestration of Floral Initiation by APETALA1

The MADS-domain transcription factor APETALA1 (AP1) is a key regulator of Arabidopsis flower development. To understand the molecular mechanisms underlying AP1 function, we identified its target genes during floral initiation using a combination of gene expression profiling and genome-wide binding studies. Many of its targets encode transcriptional regulators, including known floral repressors. The latter genes are down-regulated by AP1, suggesting that it initiates floral development by abrogating the inhibitory effects of these genes. Although AP1 acts predominantly as a transcriptional repressor during the earliest stages of flower development, at more advanced stages it also activates regulatory genes required for floral organ formation, indicating a dynamic mode of action. Our results further imply that AP1 orchestrates floral initiation by integrating growth, patterning, and hormonal pathways

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector