Multiplicity dependence of inclusive J/psi production at midrapidity in pp collisions at root s=13 TeV

Measurements of the inclusive J/psi yield as a function of charged-particle pseudorapidity density dN(ch)/d eta in pp collisions at root s = 13 TeV with ALICE at the LHC are reported. The J/psi meson yield is measured at midrapidity (vertical bar y vertical bar <0.9) in the dielectron channel, for events selected based on the charged-particle multiplicity at midrapidity (vertical bar eta vertical bar <1) and at forward rapidity (-3.7 <eta <-1.7 and 2.8 <eta <5.1); both observables are normalized to their corresponding averages in minimum bias events. The increase of the normalized J/psi yield with normalized dN(ch)/d eta is significantly stronger than linear and dependent on the transverse momentum. The data are compared to theoretical predictions, which describe the observed trends well, albeit not always quantitatively. (C) 2020 European Organization for Nuclear Research. Published by Elsevier B.V.Peer reviewe

Assessing the effect of machine automation on operator heart and breathing rate during mechanical harvesting of wild blueberries

Wild blueberries (Vaccinium angustifolium Ait.) are among eastern Canada's most economically important crops. Despite this, the industry faces significant labor shortages required to harvest the over 69 000 ha of wild blueberry land each year. Automation of the wild blueberry is among the leading areas of wild blueberry research. The requirement to automate several different aspects of the harvester means that at present an operator is still required in the tractor. To determine the impacts that automation features have on an operator, and to assess the potential to replace skilled operators with unskilled ones, heart and respiration rates were monitored across various automatic, semiautomatic and manual harvesting conditions. Across both years of the study, the skilled operator experienced a 13.83% decrease in average heart rate under the fully automated condition versus the fully manual condition. Similarly, the new operator experienced a 19.03% decrease in average heart rate for the same scenario. While a conclusive determination cannot be made due to the significant interaction effect, it was likewise interesting to note that the skilled operator seemed to benefit more from the automated head adjustment while the new operator seemed to benefit more from the autosteer. Respiration rate data did not yield a conclusive trend, though the highest respiration rates were seen under the fully manual harvesting condition in all but the 2022 new operator data. In all, this study lays significant groundwork in the justification of automation for addressing the skilled labor shortage and for the eventual full automation of the wild blueberry harvester

Determination of Silicon Accumulation in Non-Bt Cotton (Gossypium hirsutum) Plants and Its Impact on Fecundity and Biology of Whitefly (Bemisia tabaci) under Controlled Conditions

Considering the resistance development-potential of whitefly (Bemisia tabaci) against control tactics with limited action mechanisms, the present study investigated the accumulation of two different silicon (Si) sources (SiO2 and K2SiO3) in cotton plants. The tested dose rates (0, 200, and 400 mg/L) of both Si sources were applied directly to the soil or through foliar application on cotton leaves. Moreover, a laboratory bioassay was also conducted to evaluate the performance of applied Si sources against the oviposition preference and biology of B. tabaci. A significantly higher Si accumulation, reduction in oviposition preference, and prolonged developmental period of all nymphs and total life cycle of B. tabaci was observed in the case of foliar-applied silicon. Similarly, among Si sources, a significant decline in the number of oviposited eggs and delay in the developmental period of B. tabaci was observed in the case of SiO2, followed by K2SiO3. Moreover, cotton plants subjected to SiO2 treatments possessed higher Si contents in their leaves than K2SiO3 treated plants. The results further revealed that both Si sources showed promising results at their higher concentrations regarding the tested parameters of Si accumulation, fecundity, and developmental period of B. tabaci. Our results strongly suggest that among emerging pest control strategies in cotton plants lies the use of foliar application of Si, which can also be incorporated in different integrated pest management programs due to its safety for humans and beneficial insect fauna. © 2022 by the authors.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Unveiling the strong interaction among hadrons at the LHC

International audienceOne of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices1,2. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons3,4,5,6 and so high-quality measurements exist only for hadrons containing up and down quarks7. Here we demonstrate that measuring correlations in the momentum space between hadron pairs8,9,10,11,12 produced in ultrarelativistic proton–proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of proton–omega baryon correlations, the effect of the strong interaction for this hadron–hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations13,14. The large number of hyperons identified in proton–proton collisions at the LHC, together with accurate modelling15 of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction

Soft-Dielectron Excess in Proton-Proton Collisions at s =13 TeV

A measurement of dielectron production in proton-proton (pp) collisions at √s=13 TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron (ee) invariant mass mee and pair transverse momentum pT,ee that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of mee, pT,ee, and event multiplicity dNch/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π0 ratio in pp and proton-nucleus collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at 0.15 < mee < 0.6 GeV/c2 and for pT,ee < 0.4 GeV/c indicates an enhancement of soft dielectrons, reminiscent of the “anomalous” soft-photon and soft-dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to 1.61 ± 0.13(stat) ± 0.17(syst, data) ± 0.34(syst, cocktail) in the ALICE acceptance. Acceptance-corrected excess spectra in mee and pT,ee are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.publishedVersio

Elliptic Flow of Electrons from Beauty-Hadron Decays in Pb-Pb Collisions at √sNN=5.02 TeV

The elliptic flow of electrons from beauty hadron decays at midrapidity ( | y | < 0.8 ) is measured in Pb-Pb collisions at √ s N N = 5.02     TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parametrized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, v 2 . The v 2 coefficient of electrons from beauty hadron decays is measured for the first time in the transverse momentum ( p T ) range 1.3 – 6     GeV / c in the centrality class 30%–50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length c τ ≈ 500     μ m compared to that of charm hadrons and most of the other background sources. The v 2 of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75     σ . The results provide insights into the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavored by the measurement at high p T , but is in agreement with the results at low p T . Transport models including substantial interactions of beauty quarks with an expanding strongly interacting medium describe the measurement within uncertainties

Unveiling the strong interaction among hadrons at the LHC

International audienceOne of the key challenges for nuclear physics today is to understand from first principles the effective interaction between hadrons with different quark content. First successes have been achieved using techniques that solve the dynamics of quarks and gluons on discrete space-time lattices1,2. Experimentally, the dynamics of the strong interaction have been studied by scattering hadrons off each other. Such scattering experiments are difficult or impossible for unstable hadrons3,4,5,6 and so high-quality measurements exist only for hadrons containing up and down quarks7. Here we demonstrate that measuring correlations in the momentum space between hadron pairs8,9,10,11,12 produced in ultrarelativistic proton–proton collisions at the CERN Large Hadron Collider (LHC) provides a precise method with which to obtain the missing information on the interaction dynamics between any pair of unstable hadrons. Specifically, we discuss the case of the interaction of baryons containing strange quarks (hyperons). We demonstrate how, using precision measurements of proton–omega baryon correlations, the effect of the strong interaction for this hadron–hadron pair can be studied with precision similar to, and compared with, predictions from lattice calculations13,14. The large number of hyperons identified in proton–proton collisions at the LHC, together with accurate modelling15 of the small (approximately one femtometre) inter-particle distance and exact predictions for the correlation functions, enables a detailed determination of the short-range part of the nucleon-hyperon interaction