1,144 research outputs found
Mitigating the risk of blackleg disease of canola using fungicide strategies
Non-Peer ReviewedBlackleg, the most widespread disease on canola on the prairies, has been managed mainly through use
of resistant cultivars in combination with crop rotation. Over the past few years, crop rotation has been
tightened in favor of canola production due largely to profitability considerations but this practice can
speed up changes in pathogen race structure that may lead to losses of resistance for some of the current
canola cultivars. In this study, fungicides strategies were assessed as a second line of defense for control
of blackleg and canola yield benefit in case when the variety resistance is overcome by the pathogen. In
2011, the fungicide Headline, Quadris, and Quilt were applied at 2-4 leaf stage and/or bolting to target
varying periods of infection at three locations on the prairies. On the susceptible cultivar Westar, an
early application (2-4 leaf) of Headline or Quadris reduced the disease at Carman, MB, but not at
Melfort or Vegreville relative to non-treated controls. None of the fungicide treatments increased canola
yield substantially either. The study will be continued for two more years at multiple locations across the
prairies
Profile instabilities of the millisecond pulsar PSR J1022+1001
We present evidence that the integrated profiles of some millisecond pulsars
exhibit severe changes that are inconsistent with the moding phenomenon as
known from slowly rotating pulsars. We study these profile instabilities in
particular for PSR J1022+1001 and show that they occur smoothly, exhibiting
longer time constants than those associated with moding. In addition, the
profile changes of this pulsar seem to be associated with a relatively
narrow-band variation of the pulse shape. Only parts of the integrated profile
participate in this process which suggests that the origin of this phenomenon
is intrinsic to the pulsar magnetosphere and unrelated to the interstellar
medium. A polarization study rules out profile changes due to geometrical
effects produced by any sort of precession. However, changes are observed in
the circularly polarized radiation component. In total we identify four
recycled pulsars which also exhibit instabilities in the total power or
polarization profiles due to an unknown phenomenon (PSRs J1022+1001,
J1730-2304, B1821-24, J2145-0750).
The consequences for high precision pulsar timing are discussed in view of
the standard assumption that the integrated profiles of millisecond pulsars are
stable. As a result we present a new method to determine pulse times-of-arrival
that involves an adjustment of relative component amplitudes of the template
profile. Applying this method to PSR J1022+1001, we obtain an improved timing
solution with a proper motion measurement of -17 \pm 2 mas/yr in ecliptic
longitude. Assuming a distance to the pulsar as inferred from the dispersion
measure this corresponds to an one-dimensional space velocity of 50 km/s.Comment: 29 pages, 12 figures, accepted for publication in Ap
Nutritional deficiency and placenta calcification underlie constitutive, selective embryo loss in pregnant South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha)
Plains vizcacha females are able to ovulate up to 800 oocytes per estrus cycle. However, just 10â12 embryos are implanted and only two of them, those located nearest the cervix, are gestated to term. Between 26 and 70 days post-coitum, a constitutive resorption occurs from the embryos located proximal to the ovary, extending progressively toward those distally implanted. Our previous studies on the dynamics of gestation in L. maximus, led us to hypothesize some kind of placental and nutritional insufficiency as the basis for the resorption process. We analyzed histology and arterial architecture of the reproductive tract in pregnant and non-pregnant females. Uterine horns are irrigated through the uterine artery, a branch of the internal iliac artery, in an ascending way from the cervix; segmental arteries irrigating the embryo vesicles become thinner as they approach the ovary. Contrast solution administered during angiographies accumulated in the placenta of embryos closest to cervix. Thus, blood stream favors the embryos nearest the cervix, indicating a gradual nutritional deficiency of those closest to the ovary. Besides, placenta becomes calcified early, at mid-gestation, during the resorption process. Finally, the detection of specialized endothelial venules and inflammatory cells suggest the concurrent participation of immunological processes in embryo vesicles undergoing resorption.Fil: Giacchino, Mariela. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad MaimĂłnides. Ărea de Investigaciones BiomĂ©dicas y BiotecnolĂłgicas. Centro de Estudios BiomĂ©dicos, BiotecnolĂłgicos, Ambientales y de DiagnĂłstico; ArgentinaFil: Claver, Juan Alberto. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. CĂĄtedra de HistologĂa y EmbriologĂas; ArgentinaFil: Inserra, Pablo Ignacio Felipe. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad MaimĂłnides. Ărea de Investigaciones BiomĂ©dicas y BiotecnolĂłgicas. Centro de Estudios BiomĂ©dicos, BiotecnolĂłgicos, Ambientales y de DiagnĂłstico; ArgentinaFil: Lange, Fernando D.. Universidad MaimĂłnides; ArgentinaFil: Gariboldi, MarĂa Constanza. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad MaimĂłnides. Ărea de Investigaciones BiomĂ©dicas y BiotecnolĂłgicas. Centro de Estudios BiomĂ©dicos, BiotecnolĂłgicos, Ambientales y de DiagnĂłstico; ArgentinaFil: Ferraris, Sergio RaĂșl. Universidad MaimĂłnides; ArgentinaFil: Vitullo, Alfredo Daniel. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad MaimĂłnides. Ărea de Investigaciones BiomĂ©dicas y BiotecnolĂłgicas. Centro de Estudios BiomĂ©dicos, BiotecnolĂłgicos, Ambientales y de DiagnĂłstico; Argentin
Impact of pre-enrolment medication use on clinical outcomes in SUMMIT
The impact of prior treatment on results of clinical trials in chronic obstructive pulmonary disease (COPD) has been debated. We used data from the Study to Understand Mortality and Morbidity in COPD Trial to examine the impact of prior treatment on the effects of randomised study drugs on mortality and exacerbations. We used data on 16â417 patients with moderate COPD and heightened cardiovascular risk and information on prior medications to examine the effects of fluticasone furoate (FF), vilanterol (VI) and combined FF/VI compared to placebo on moderate and severe exacerbation as well as mortality. The study was event-driven with a median study exposure of 1.8 years. This study was registered with ClinicalTrials.gov, number NCT01313676. There were no consistent associations between treatment prior to study entry and the effects of FF, VI or FF/VI on exacerbations during the study. However, patients taking inhaled corticosteroids and one or more bronchodilators prior to study entry seemed to have a better effect of active treatments than of placebo on mortality (hazard ratio for FF/VI 0.65, 95% CI 0.48â0.89). Survival in those randomised to placebo was independent of treatment prior to study enrolment. Prior treatment appears to affect treatment effects on mortality but not exacerbations in a randomised controlled trial of patients with COPD and heightened cardiovascular risk
FEV1 is a stronger mortality predictor than FVC in mild-to-moderate patients with COPD and an increased risk for cardiovascular disease
Measurement of ISR-FSR interference in the processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma
Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi-
gamma is measured using 232 fb-1 of data collected with the BABAR detector at
center-of-mass energies near 10.58 GeV. An observable is introduced and shown
to be very robust against detector asymmetries while keeping a large
sensitivity to the physical charge asymmetry that results from the interference
between initial and final state radiation. The asymmetry is determined as
afunction of the invariant mass of the final-state tracks from production
threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e-
--> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A
clear interference pattern is observed in e+ e- --> pi+ pi- gamma, particularly
in the vicinity of the f_2(1270) resonance. The inferred rate of lowest order
FSR production is consistent with the QED expectation for e+ e- --> mu+ mu-
gamma, and is negligibly small for e+ e- --> pi+ pi- gamma.Comment: 32 pages,29 figures, to be submitted to Phys. Rev.
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
Measurement of Ï c1 and Ï c2 production with sâ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the Ï c1 and Ï c2 charmonium states are measured in pp collisions at sâ = 7 TeV with the ATLAS detector at the LHC using 4.5 fbâ1 of integrated luminosity. The Ï c states are reconstructed through the radiative decay Ï c â J/ÏÎł (with J/Ï â ÎŒ + ÎŒ â) where photons are reconstructed from Îł â e + e â conversions. The production rate of the Ï c2 state relative to the Ï c1 state is measured for prompt and non-prompt Ï c as a function of J/Ï transverse momentum. The prompt Ï c cross-sections are combined with existing measurements of prompt J/Ï production to derive the fraction of prompt J/Ï produced in feed-down from Ï c decays. The fractions of Ï c1 and Ï c2 produced in b-hadron decays are also measured
Measurement of the production of a W boson in association with a charm quark in pp collisions at âs = 7 TeV with the ATLAS detector
The production of a W boson in association with a single charm quark is studied using 4.6 fbâ1 of pp collision data at sâ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26â0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio Ï(W + +cÂŻÂŻ)/Ï(W â + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the sâsÂŻÂŻÂŻ quark asymmetry
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