389 research outputs found
Athletes’ Beliefs About and Attitudes Towards Taking Banned Performance-Enhancing Substances: A Qualitative Study
Elite athletes’ beliefs about, and attitudes toward, taking banned performance enhancing substances were explored in 8 focus-group discussions with 57 athletes from 7 different sports. Discussion was initiated by 3 broad open-ended questions pertaining to 3 important themes likely to affect beliefs and attitudes toward banned performance enhancing substances. Thematic content analysis of interview transcripts revealed 9 lower-order themes emerging under the 3 global themes: personal attitudes (reputation and getting caught, health effects, and financial incentives and rewards), social influences (coaches, parents, and medical staff and sport scientists), and control beliefs (i.e., insufficiency of doping testing, resource availability, and sport level and type). Findings provide insight into the beliefs and attitudes that likely underpin motives and intentions to take banned performance-enhancing substances. Results are generally consistent with, and complement, research adopting quantitative approaches based on social– cognitive models examining the beliefs and attitudes linked to taking banned performance-enhancing substances
Self-Control, Self-Regulation, and Doping in Sport: A Test of the Strength-Energy Model
We applied the strength-energy model of self-control to understand the relationship between self-control and young athletes’ behavioral responses to taking illegal performance-enhancing substances, or “doping.” Measures of trait self-control, attitude and intention toward doping, intention toward, and adherence to, doping-avoidant behaviors, and the prevention of unintended doping behaviors were administered to 410 young Australian athletes. Participants also completed a “lollipop” decision-making protocol that simulated avoidance of unintended doping. Hierarchical linear multiple regression analyses revealed that self-control was negatively associated with doping attitude and intention, and positively associated with the intention and adherence to doping-avoidant behaviors, and refusal to take or eat the unfamiliar candy offered in the “lollipop” protocol. Consistent with the strength-energy model, athletes with low self-control were more likely to have heightened attitude and intention toward doping, and reduced intention, behavioral adherence, and awareness of doping avoidance
r-2,c-6-Bis(4-methoxyphenyl)-c-3,t-3-dimethylpiperidin-4-one
The asymmetric unit of the title compound, C21H25NO3, contains two crystallographically independent molecules (A and B). In both molecules, the piperidine ring adopts a chair conformation, with the methoxyphenyl rings attached equatorially. The dihedral angle between the two benzene rings in molecule A is 73.79 (8)°; the corresponding value in molecule B is 77.71 (8)°. The molecules are linked by N—H⋯O hydrogen bonds. In addition, C—H⋯π interactions are also found in the crystal structure
1-Benzyl-3,5-bis(4-chlorobenzylidene)piperidin-4-one
The title compound, C26H21Cl2NO, crystallizes with two symmetry-independent molecules (A and B) in the asymmetric unit. In both molecules, the central heterocyclic ring adopts a sofa conformation. The dihedral angles between the planar part of this central heterocyclic ring [maximum deviations of 0.011 (1) and 0.036 (1) Å in molecules A and B, respectively] and the two almost planar [maximum deviations of 0.020 (1) and 0.008 (1) Å in A and 0.007 (1) and 0.011 (1) in B] side-chain fragments that include the aromatic ring and bridging atoms are 20.1 (1) and 31.2 (1)° in molecule A, and 26.4 (1) and 19.6 (1)° in molecule B. The dihedral angles between the planar part of the heterocyclic ring and the benzyl substituent are 79.7 (1) and 53.2 (1)° in molecules A and B, respectively. In the crystal, weak intermolecular C—H⋯O hydrogen bonds link the two independent molecules into dimers
(E)-1-(6-Chloro-2-methyl-4-phenyl-3-quinolyl)-3-(4-ethoxyphenyl)prop-2-en-1-one
In the title compound, C27H22ClNO2, the phenyl substituent on the quinoline ring system is almost perpendicular to it [dihedral angle = 88.2 (1)°]. The quinoline ring system and the ethoxyphenyl ring are oriented at dihedral angles of 79.5 (1) and 17.6 (3)°, respectively, with respect to the almost planar [r.m.s. deviation= 0.037 (3) Å] –C(=O)—C=C– linkage. In the crystal, the inversion-related molecules exist as C—H⋯O hydrogen-bonded R
2
2(8) dimers
The Link Between Shocks, Turbulence and Magnetic Reconnection in Collisionless Plasmas
Global hybrid (electron fluid, kinetic ions) and fully kinetic simulations of the magnetosphere have been used to show surprising interconnection between shocks, turbulence and magnetic reconnection. In particular collisionless shocks with their reflected ions that can get upstream before retransmission can generate previously unforeseen phenomena in the post shocked flows: (i) formation of reconnecting current sheets and magnetic islands with sizes up to tens of ion inertial length. (ii) Generation of large scale low frequency electromagnetic waves that are compressed and amplified as they cross the shock. These \u27wavefronts\u27 maintain their integrity for tens of ion cyclotron times but eventually disrupt and dissipate their energy. (iii) Rippling of the shock front, which can in turn lead to formation of fast collimated jets extending to hundreds of ion inertial lengths downstream of the shock. The jets, which have high dynamical pressure, \u27stir\u27 the downstream region, creating large scale disturbances such as vortices, sunward flows, and can trigger flux ropes along the magnetopause. This phenomenology closes the loop between shocks, turbulence and magnetic reconnection in ways previously unrealized. These interconnections appear generic for the collisionless plasmas typical of space, and are expected even at planar shocks, although they will also occur at curved shocks as occur at planets or around ejecta
Ethyl 4-(3-bromo-2-thienyl)-2-oxo-6-phenylcyclohex-3-ene-1-carboxylate
The title compound, C19H17BrO3S, crystallizes with two molecules in the asymmetric unit. The methyl group of one molecule is disordered approximately equally over two positions. The dihedral angles between the thiophene and phenyl groups are 68.5 (2) and 67.5 (2)° in the two molecules
Ion Dynamics Across a Low Mach Number Bow Shock
A thorough understanding of collisionless shocks requires knowledge of how
different ion species are accelerated across the shock. We investigate a bow
shock crossing using the Magnetospheric Multiscale spacecraft after a coronal
mass ejection crossed Earth, which led to solar wind consisting of protons,
alpha particles, and singly charge helium ions. The low Mach number of the bow
shock enabled the ions to be distinguished upstream and sometimes downstream of
the shock. Some of the protons are specularly reflected and produce
quasi-periodic fine structures in the velocity distribution functions
downstream of the shock. Heavier ions are shown to transit the shock without
reflection. However, the gyromotion of the heavier ions partially obscures the
fine structure of proton distributions. Additionally, the calculated proton
moments are unreliable when the different ion species are not distinguished by
the particle detector. The need to high time-resolution mass-resolving ion
detectors when investigating collisionless shocks is discussed.Comment: 16 pages, 5 figure
Excitonic effects on the two-color coherent control of interband transitions in bulk semiconductors
Quantum interference between one- and two-photon absorption pathways allows
coherent control of interband transitions in unbiased bulk semiconductors;
carrier population, carrier spin polarization, photocurrent injection, and spin
current injection may all be controlled. We extend the theory of these
processes to include the electron-hole interaction. Our focus is on photon
energies that excite carriers above the band edge, but close enough to it so
that transition amplitudes based on low order expansions in are
applicable; both allowed-allowed and allowed-forbidden two-photon transition
amplitudes are included. Analytic solutions are obtained using the effective
mass theory of Wannier excitons; degenerate bands are accounted for, but
envelope-hole coupling is neglected. We find a Coulomb enhancement of two-color
coherent control process, and relate it to the Coulomb enhancements of one- and
two-photon absorption. In addition, we find a frequency dependent phase shift
in the dependence of photocurrent and spin current on the optical phases. The
phase shift decreases monotonically from at the band edge to 0 over an
energy range governed by the exciton binding energy. It is the difference
between the partial wave phase shifts of the electron-hole envelope function
reached by one- and two-photon pathways.Comment: 31 pages, 4 figures, to be published in Phys. Rev.
3,5-Bis(4-chlorobenzylidene)-1-methylpiperidin-4-one
In the title molecule, C20H17Cl2NO, the central heterocyclic ring adopts a flattened boat conformation. The dihedral angles between the planar part of this central heterocyclic ring [maximum deviation = 0.004 (1) Å] and the two almost planar side-chain fragments [maximum deviations = 0.015 (1) and 0.019 (1) Å], that include the aromatic ring and bridging atoms, are 18.1 (1) and 18.0 (1)°. In the crystal, pairs of weak intermolecular C—H⋯O hydrogen bonds link molecules into inversion dimers that form stacks along the a axis. The structure is further stabilized by weak intermolecular C—H⋯π interactions involving the benzene rings
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