366 research outputs found
Control quĂmico de malezas en cĂtricos
Se evaluĂł la efectividad y residualidad de algunos herbicidas en cultivos de cĂtricos en el sur del Departamento del AtlĂĄntico. Se empleĂł un diseĂąo de bloques al azar con 3 replicaciones, empleando parcelas de 4 x 4 m. Para la evaluaciĂłn de la fitotoxicidad al cultivo y residualidad de los productos, se tomaron datos quincenales del porcentaje de ĂĄrea cubierta de gramĂneas como de malezas de hoja ancha, durante 330 dĂas, habiĂŠndose realizado 18 observaciones. Las parcelas fueron inicialmente desenmalezadas y limpiadas. Los tratamientos mĂĄs promisorios por su buen control y residualidad larga para el control de malezas en cĂtricos, fueron los siguientes: Diuron (4 kg/ha), Terbacil (2 kg/ha), Atrazina (2 kg/ha) mĂĄs Diuron (2 kg/ha), Atrazina (4 kg/ha) y Atrazina (2 kg/ha) mĂĄs CP 50144 (2 kg/ha). Para el control de malezas de hoja ancha se recomienda aplicar: Amitrol T (4 kg/ha) y 2,4-D (2 kg/ha). Para controlar gramĂneas: Pyriclor (1 kg/ha) y DalapĂłn (6 kg/ha). Se seĂąala que el uso de Amitrol T, Paraquat, Dalapon, Pyriclor y 2,4-D requieren protecciĂłn al follaje durante las aplicacione
Structural And Magnetic Study Of Labacocu O5+δ
The structure and magnetic properties of the compound LaBaCuCo O5+δ have been studied for the non-stoichiometric oxygen concentration δâ0.6. The structure is pseudo-cubic with a tripled perovskite unit cell. The crystal structure was determined by a combined Rietveld fit to neutron and synchrotron x-ray powder diffraction data in the orthorhombic Pmmm space group, with cell parameters a=3.9223 (3) Ă
, b=3.9360 (3) Ă
, c=11.7073 (8) Ă
, and V=180.74 (2) Ă
3 (room temperature). Antiferromagnetic ordering of Cu and Co magnetic moments is observed below 205 (4) K. The magnetic structure with cell aM =2a, bM =2b, and cM =2c, could be described with the Shubnikov space group Fmm mâ˛. The magnetic moments of both equivalent Cu/Co sites were determined at 50 and 170 K to be 0.83 (3) ÎźB and 0.58 (3) ÎźB, respectively, consistent with one unpaired electron per atom. The fit of the intensities to a simple mean field magnetic model appeared to be insufficient to account for the variation of moments at temperatures close to TN while a three dimensional Heisenberg model could improve the fit. Susceptibility measurements between 4 and 350 K also show irreversibility below 150 K. The local environments of Cu and Co were studied by extended x-ray absorption fine structure spectroscopy at both absorption edges. 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Dynamic Vortex Phases and Pinning in Superconductors with Twin Boundaries
We investigate the pinning and driven dynamics of vortices interacting with
twin boundaries using large scale molecular dynamics simulations on samples
with near one million pinning sites. For low applied driving forces, the vortex
lattice orients itself parallel to the twin boundary and we observe the
creation of a flux gradient and vortex free region near the edges of the twin
boundary. For increasing drive, we find evidence for several distinct dynamical
flow phases which we characterize by the density of defects in the vortex
lattice, the microscopic vortex flow patterns, and orientation of the vortex
lattice. We show that these different dynamical phases can be directly related
to microscopically measurable voltage - current V(I) curves and voltage noise.
By conducting a series of simulations for various twin boundary parameters we
derive several vortex dynamic phase diagrams.Comment: 5 figures, to appear in Phys. Rev.
Synthesis of 2H-benzotriazole based donor-acceptor polymers bearing carbazole derivative as pendant groups: Optical, electronical and photovoltaic properties
 Four 2H-benzotriazole based D-A polymers bearing carbazole derivative as pendant groups and fluorene or thiophene as donor units (P1-P4) were designed and synthesized. These polymers combine good thermal stability and excellent solubility in common organic solvents. Spectroscopic measurements carried out for P1, P2 and P3 indicate that polymer backbone induces effective the quenching of the 3,6-di(thiophen-2-yl)-9H-carbazole (CT) fluorescence, implying an intramolecular FĂśrster Resonance Energy Transfer (FRET) process. Preliminary investigations on the photovoltaic multiheterojunction devices based on P1-P4 showed power conversion efficiencies (PCEs) of up to 1.7 % for P1 and P2 and close to 2.0 % for P3. This means that the polymer/Ď-conjugated pendant units structure is a promising alternative to improve the performance of organic solar cells
The ArcAB two-component regulatory system promotes resistance to reactive oxygen species and systemic infection by Salmonella Typhimurium
Indexación: Scopus.Funding:Thisworkwassupportedby"Fondo NacionaldeCienciayTecnologia"FONDECYT Grants#1120384and#1160315(toCPS),Grant PFB-16(toRP)from"Comisio ´nNacionalde Investigacio ´ n CientĹ ´ fica y Tecnolo ´ gica de Chile" (CONICYT)andUniversidadAndresBelloNucleo GrantDI-3-17/N(toCPS),andDoctoralSalmonella enterica Serovar Typhimurium (S. Typhimurium) is an intracellular bacterium that overcomes host immune system barriers for successful infection. The bacterium colonizes the proximal small intestine, penetrates the epithelial layer, and is engulfed by macrophages and neutrophils. Intracellularly, S. Typhimurium encounters highly toxic reactive oxygen species including hydrogen peroxide and hypochlorous acid. The molecular mechanisms of Salmonella resistance to intracellular oxidative stress is not completely understood. The ArcAB two-component system is a global regulatory system that responds to oxygen. In this work, we show that the ArcA response regulator participates in Salmonella adaptation to changing oxygen levels and is also involved in promoting intracellular survival in macrophages and neutrophils, enabling S. Typhimurium to successfully establish a systemic infection. Š 2018 Pardo-EstÊ et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.https://journals.plos.org/plosone/article?id=10.1371/journal.pone.020349
Consenso colombiano de atenciĂłn, diagnĂłstico y manejo de la infecciĂłn por SARS-COV-2/COVID-19 en establecimientos de atenciĂłn de la salud Recomendaciones basadas en consenso de expertos e informadas en la evidencia
The âAsociaciĂłn Colombiana de InfectologĂaâ (ACIN) and the âInstituto de EvaluaciĂłn de Nuevas TecnologĂas de la Saludâ (IETS) created a task force to develop recommendations for Covid 19 health care diagnosis, management and treatment informed, and based, on evidence. Theses reccomendations are addressed to the health personnel on the Colombian context of health services. Š 2020 Asociacion Colombiana de Infectologia. All rights reserved
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
Search for new physics in events with opposite-sign leptons, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV
A search is presented for physics beyond the standard model (BSM) in final
states with a pair of opposite-sign isolated leptons accompanied by jets and
missing transverse energy. The search uses LHC data recorded at a
center-of-mass energy sqrt(s) = 7 TeV with the CMS detector, corresponding to
an integrated luminosity of approximately 5 inverse femtobarns. Two
complementary search strategies are employed. The first probes models with a
specific dilepton production mechanism that leads to a characteristic kinematic
edge in the dilepton mass distribution. The second strategy probes models of
dilepton production with heavy, colored objects that decay to final states
including invisible particles, leading to very large hadronic activity and
missing transverse energy. No evidence for an event yield in excess of the
standard model expectations is found. Upper limits on the BSM contributions to
the signal regions are deduced from the results, which are used to exclude a
region of the parameter space of the constrained minimal supersymmetric
extension of the standard model. Additional information related to detector
efficiencies and response is provided to allow testing specific models of BSM
physics not considered in this paper.Comment: Replaced with published version. Added journal reference and DO
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