1,492 research outputs found

    Electric-field-induced alignment of electrically neutral disk-like particles: modelling and calculation

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    This work reveals a torque from electric field to electrically neutral flakes that are suspended in a higher electrical conductive matrix. The torque tends to rotate the particles toward an orientation with its long axis parallel to the electric current flow. The alignment enables the anisotropic properties of tiny particles to integrate together and generate desirable macroscale anisotropic properties. The torque was obtained from thermodynamic calculation of electric current free energy at various microstructure configurations. It is significant even when the electrical potential gradient becomes as low as 100 v/m. The changes of electrical, electroplastic and thermal properties during particles alignment were discussed

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

    Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

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    The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

    Observation of associated near-side and away-side long-range correlations in √sNN=5.02  TeV proton-lead collisions with the ATLAS detector

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    Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

    \u3ci\u3eUncle Tom’s Cabin\u3c/i\u3e in \u3ci\u3eThe National Era\u3c/i\u3e: Commentary on Chapter 1 and 2

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    In the first chapter of Uncle Tom’s Cabin, Stowe warns her readers that the “indulgence” of slave owners and the “affectionate loyalty” of the slaves themselves towards their masters have misled some observers to believe the “poetic legend” of slavery as a benevolent “patriarchal institution.” She does not deny the genuineness of these emotions, but she warns that “the shadow of a Law” makes a mockery of the human relationships that develop between masters and slaves: “So long as the law considers all these human beings, with beating hearts and living affections, only as so many things belonging to a master—so long as the failure, or misfortune, or imprudence, or death, of the kindest owner, may cause them any day to exchange a life of kind protection and indulgence for one of hopeless misery and toil, so long it is impossible to make anything beautiful or desirable in the best regulated administration of slavery.” We begin the novel, then, in what seems to be the model benevolent Shelby plantation in Kentucky, not the cruel Legree plantation in Louisiana, where the novel ends. Nevertheless, the “shadow of the law,” in the form of Mr. Shelby’s obligation to pay his debts, endangers the residents of the Shelby plantation. Stowe derived her portrait of slavery primarily from reading, not from direct experience and observation in the slave states of the South. She describes Eliza Harris as “not a fancy sketch, but taken from a remembrance, as we saw her years ago in Kentucky”—that is, during Stowe’s one brief trip South of the Mason-Dixon line during her years living in Cincinnati. Some white Southerners attacked Stowe for this lack of direct knowledge of the South and slavery. However, as historian William R. Taylor observed fifty years ago, what troubled them the most about Uncle Tom’s Cabin was not that she attacked their point of view, but that she understood it too well. As Taylor explains, beginning in the 1830s white Southerners invented the legend of “plantation paternalism,” “the image of sunshine and happiness around the plantation home,” to “justif[y] their peculiar institution to themselves and to others.”[1] Stowe only “[took] the Southerner at his word”: she did “not…deny the Southern defense of slavery but…suggested that it was inadequate, even if its claims were allowed.” Stowe set out to show, Taylor explains, that “kindness, generosity and affection provided no assurance against cruelty and brutality” and that “a slave could love his master and mistress and still wish to be free.”[2
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