Conformal Newton–Hooke symmetry of Pais–Uhlenbeck oscillator

K.A. and J.G. are grateful to Piotr Kosiński for helpful and illuminating discussions. We thank Peter Horváthy and Andrei Smilga for useful correspondence. This work was sup-ported by the NCN grant DEC-2013/09/B/ST2/02205 (K.A. and J.G.) and by the RFBR grants 13-02-90602-Arm (A.G.) and 14-02-31139-Mol (I.M.) as well as by the MSU program “Nauka” under the project 825 (A.G. and I.M.). I.M. gratefully acknowledges the support of the Dynasty Foundation. ©2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). Funded by SCOAP3.It is demonstrated that the Pais–Uhlenbeck oscillator in arbitrary dimension enjoys the l -conformal Newton–Hooke symmetry provided frequencies of oscillation form the arithmetic sequence ωk=(2k−1)ω1, where k=1,…,n, and l is the half-integer View the MathML source. The model is shown to be maximally superintegrable. A link to n decoupled isotropic oscillators is discussed and an interplay between the l-conformal Newton–Hooke symmetry and symmetries characterizing each individual isotropic oscillator is analyzed.This work was sup-ported by the NCN grant DEC-2013/09/B/ST2/02205 (K.A. and J.G.) and by the RFBR grants 13-02-90602-Arm (A.G.) and 14-02-31139-Mol (I.M.) as well as by the MSU program “Nauka” under the project 825 (A.G. and I.M.). I.M. gratefully acknowledges the support of the Dynasty Foundation

Electrodynamics of the vortex lattice in untwinned YBaCuO by complex impedance measurements

We report complex impedance measurements in an untwinned YBaCuO crystal. Our broad frequency range covers both the quasi static response and the resistive response of the vortex lattice. It allow us to characterize the irreversibility line without the need of any frequency dependent pinning parameters. We confirm the validity of the two modes model of vortex dynamic, and extract both the surface critical current and the flux flow resistivity around the first order transition $T_{m}$. This latter is identified by the abrupt loss of pinning and by an unexpected step of $\rho_{ff}(T)$ at $T_{m}$.Comment: accepted for publication in EPJ

A segmented total energy detector (sTED) for (n, γ) cross section measurements at n_TOF EAR2

This work was supported in part by the I+D+i grant PGC2018-096717-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by the European Commission H2020 Framework Programme project SANDA (Grant agreement ID: 847552).The neutron time-of-flight facility n_TOF is characterised by its high instantaneous neutron intensity, high resolution and broad neutron energy spectra, specially conceived for neutron-induced reaction cross section measurements. Two Time-Of-Flight (TOR) experimental areas are available at the facility: experimental area 1 (EAR1), located at the end of the 185 m horizontal flight path from the spallation target, and experimental area 2 (EAR2), placed at 20 m from the target in the vertical direction. The neutron fluence in EAR2 is similar to 300 times more intense than in EARL in the relevant time-of-flight window. EAR2 was designed to carry out challenging cross-section measurements with low mass samples (approximately 1 mg), reactions with small cross-sections or/and highly radioactive samples. The high instantaneous fluence of EAR2 results in high counting rates that challenge the existing capture systems. Therefore, the sTED detector has been designed to mitigate these effects. In 2021, a dedicated campaign was done validating the performance of the detector up to at least 300 keV neutron energy. After this campaign, the detector has been used to perform various capture cross section measurements at n_TOF EAR2.MCIN/AEI/10.13039/501100011033 I+D+i PGC2018-096717-B-C21European Commission H2020 Framework Programme SANDA 84755

My grade, my right: linking academic entitlement to academic performance

The identifcation of determinants and correlates of academic entitlement is of particular interest for researchers and (academic) tutors alike. Whilst personality traits have been linked to academic entitlement in the past, the relative importance of familial influence remains unclear. Hence, to address this deficit, this study utilizes a sample of business and psychology undergraduates (N=170) in the United Arab Emirates. Additionally, the impact of academic entitlement on students’ misestimation of coursework grades was assessed in a subsample of psychology undergraduates (N=92). Multiple regression analyses revealed honesty–humility as the strongest predictor of academic entitlement, indicating lower entitlement of more honest students. In contrast, familial influences were unrelated to academic entitlement. Interestingly, higher entitled expectations were associated with larger overestimation of grades. Our findings indicate honesty–humility as an important driver of academic entitlement, whilst entitled expectations appear to be associated with misperceptions of students' own academic performance

Shower approach in the simulation of ion scattering from solids

An efficient approach for the simulation of ion scattering from solids is proposed. For every encountered atom, we take multiple samples of its thermal displacements among those which result in scattering with high probability to finally reach the detector. As a result, the detector is illuminated by intensive "showers", where each event of detection must be weighted according to the actual probability of the atom displacement. The computational cost of such simulation is orders of magnitude lower than in the direct approach and a comprehensive analysis of multiple and plural scattering effects becomes possible. We use the new method for two purposes. First, the accuracy of the approximate approaches, developed mainly for ion-beam structural analysis, is verified. Second, the possibility to reproduce a wide class of experimental conditions is used to analyze some basic features of ion-solid collisions: the role of double violent collisions in low-energy ion scattering; the origin of the "surface peak" in scattering from amorphous samples; the low-energy tail in the energy spectra of scattered medium-energy ions due to plural scattering; the degradation of blocking patterns in 2D angular distributions with increasing depth of scattering. As an example of simulation for ions of MeV energies, we verify the time-reversibility for channeling/blocking of 1 MeV protons in a W crystal. The possibilities of analysis that our approach offers may be very useful for various applications in particular for structural analysis with atomic resolution.Comment: 16 pages, 9 figures. Finally published version; large parts reformulated, Fig. 9 and references adde