1,676 research outputs found

    Folding energy and kinetics of mutually interacting DNA Hairpins

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    Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2020, Tutors: Marc Rico, Fèlix RitortThe Szilard engine is a Maxwell demon thought experiment where information is converted into work. We propose a novel DNA molecule with two hairpins in serial that could act as a complex four-state Szilard engine using optical tweezers to apply a force. We synthesized the molecule with identical hairpins to perform two different experiments with optical tweezers, passive mode and pulling. Only 3 different states were observed as the intermediate state is degenerated. Their energy levels were obtained from kinetic rates measured in passive mode and work measured in pulling cycles. We conclude that the molecule follows well the uctuation theorems and the Bell-Evans theory, with the exception of a Chevron type curvature in the kinetic rates due to the degeneration. The obtained data will help in the development and study of a Szilard engine with this molecule

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum
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