1,609 research outputs found
Capturing doping attitudes by self-report declarations and implicit assessment: a methodology study
BACKGROUND: Understanding athletes' attitudes and behavioural intentions towards performance enhancement is critical to informing anti-doping intervention strategies. Capturing the complexity of these attitudes beyond verbal declarations requires indirect methods. This pilot study was aimed at developing and validating a method to assess implicit doping attitudes using an Implicit Associations Test (IAT) approach. METHODS: The conventional IAT evaluation task (categorising 'good' and 'bad' words) was combined with a novel 'doping' versus 'nutrition supplements' category pair to create a performance-enhancement related IAT protocol (PE-IAT). The difference between average response times to 'good-doping' and 'bad-doping' combinations represents an estimate of implicit attitude towards doping in relation to nutritional supplements. 111 sports and exercise science undergraduates completed the PE-IAT, the Performance Enhancement Attitude Scale (PEAS) and answered questions regarding their beliefs about doping. RESULTS: Longer response times were observed in the mixed category discrimination trials where categories 'good' and 'doping' shared the same response key (compared to 'bad-doping' combination on the same key) indicating a less favourable evaluation of doping substances. The PE-IAT measure did not correlate significantly with the declared doping attitudes (r = .181, p = .142), indicating a predictable partial dissociation. Action-oriented self-report expressed stronger associations with PE-IAT: participants who declared they would consider using doping showed significantly less implicit negativity towards banned substances (U = 109.00, p = .047). Similarly, those who reported more lenient explicit attitudes towards doping or expressly supported legalizing it, showed less implicit negativity towards doping in the sample, although neither observed differences reached statistical significance (t = 1.300, p = .198, and U = 231.00, p = .319, respectively). Known-group validation strategy yielded mixed results: while competitive sport participants scored significantly lower than non-competitive ones on the PEAS (t = -2.71, p = .008), the two groups did not differ on PE-IAT (t = -.093, p = .926). CONCLUSION: The results suggest a potential of the PE-IAT method to capture undeclared attitudes to doping and predict behaviour, which can support targeted anti-doping intervention and related research. The initial evidence of validity is promising but also indicates a need for improvement to the protocol and stimulus material
Eruptive Event Generator Based on the Gibson-Low Magnetic Configuration
Coronal Mass Ejections (CMEs), a kind of energetic solar eruptions, are an
integral subject of space weather research. Numerical magnetohydrodynamic (MHD)
modeling, which requires powerful computational resources, is one of the
primary means of studying the phenomenon. With increasing accessibility of such
resources, grows the demand for user-friendly tools that would facilitate the
process of simulating CMEs for scientific and operational purposes. The
Eruptive Event Generator based on Gibson-Low flux rope (EEGGL), a new publicly
available computational model presented in this paper, is an effort to meet
this demand. EEGGL allows one to compute the parameters of a model flux rope
driving a CME via an intuitive graphical user interface (GUI). We provide a
brief overview of the physical principles behind EEGGL and its functionality.
Ways towards future improvements of the tool are outlined
A Titov-D\'emoulin Type Eruptive Event Generator for Plasmas
We provide exact analytical solutions for the magnetic field produced by
prescribed current distributions located inside a toroidal filament of finite
thickness. The solutions are expressed in terms of toroidal functions which are
modifications of the Legendre functions. In application to the MHD equilibrium
of a twisted toroidal current loop in the solar corona, the Grad-Shafranov
equation is decomposed into an analytic solution describing an equilibrium
configuration against the pinch-effect from its own current and an approximate
solution for an external strapping field to balance the hoop force. Our
solutions can be employed in numerical simulations of coronal mass ejections.
When superimposed on the background solar coronal magnetic field, the excess
magnetic energy of the twisted current loop configuration can be made unstable
by applying flux cancellation to reduce the strapping field. Such loss of
stability accompanied by the formation of an expanding flux rope is typical for
the Titov & D\'emoulin (1999) eruptive event generator. The main new features
of the proposed model are: (i) The filament is filled with finite
plasma with finite mass and energy, (ii) The model describes an equilibrium
solution that will spontaneously erupt due to magnetic reconnection of the
strapping magnetic field arcade, and (iii) There are analytic expressions
connecting the model parameters to the asymptotic velocity and total mass of
the resulting CME, providing a way to connect the simulated CME properties to
multipoint coronograph observations.Comment: 20 pages, 7 figure
High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae
"High-velocity features" (HVFs) are spectral features in Type Ia supernovae
(SNe Ia) that have minima indicating significantly higher (by greater than
about 6000 km/s) velocities than typical "photospheric-velocity features"
(PVFs). The PVFs are absorption features with minima indicating typical
photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near
B-band maximum brightness). In this work we undertake the most in-depth study
of HVFs ever performed. The dataset used herein consists of 445 low-resolution
optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum
brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A
series of Gaussian functions is fit to the data in order to characterise
possible HVFs of Ca II H&K, Si II {\lambda}6355, and the Ca II NIR triplet. The
temporal evolution of the velocities and strengths of the PVFs and HVFs of
these three spectral features is investigated, as are possible correlations
with other SN Ia observables. We find that while HVFs of Ca II are regularly
observed (except in underluminous SNe Ia, where they are never found), HVFs of
Si II {\lambda}6355 are significantly rarer, and they tend to exist at the
earliest epochs and mostly in objects with large photospheric velocities. It is
also shown that stronger HVFs of Si II {\lambda}6355 are found in objects that
lack C II absorption at early times and that have red ultraviolet/optical
colours near maximum brightness. These results lead to a self-consistent
connection between the presence and strength of HVFs of Si II {\lambda}6355 and
many other mutually correlated SN~Ia observables, including photospheric
velocity.Comment: 48 pages (22 of which are tables), 15 figures, 5 tables, re-submitted
to MNRAS (after first referee report
CALIPSO Observations of Transatlantic Dust: Vertical Stratification and Effect of Clouds
CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios during the summer of 2007 are used to study transatlantic dust properties downwind of Saharan sources, and to examine the interaction of clouds and dust. We discuss the following findings: (1) while lidar backscatter doesn't change much with altitude in the Saharan Air Layer (SAL), depolarization and color ratios both increase with altitude in the SAL; (2) lidar backscatter and color ratio increase as dust is transported westward in the SAL; (3) the vertical lapse rate of dust depolarization ratio increases within SAL as plumes move westward; (4) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Finally, (5) the odds of CALIOP finding dust below SAL next to clouds are about 2/3 of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dusty volumes lose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust
Probing the Edge of the Solar System: Formation of an Unstable Jet-Sheet
The Voyager spacecraft is now approaching the edge of the solar system. Near
the boundary between the solar system and the interstellar medium we find that
an unstable ``jet-sheet'' forms. The jet-sheet oscillates up and down due to a
velocity shear instability. This result is due to a novel application of a
state-of-art 3D Magnetohydrodynamic (MHD) code with a highly refined grid. We
assume as a first approximation that the solar magnetic and rotation axes are
aligned. The effect of a tilt of the magnetic axis with respect to the rotation
axis remains to be seen. We include in the model self-consistently magnetic
field effects in the interaction between the solar and interstellar winds.
Previous studies of this interaction had poorer spatial resolution and did not
include the solar magnetic field. This instability can affect the entry of
energetic particles into the solar system and the intermixing of solar and
interstellar material. The same effect found here is predicted for the
interaction of rotating magnetized stars possessing supersonic winds and moving
with respect to the interstellar medium, such as O stars.Comment: 9 pages, 4 figures, accepted for publication in ApJ
- …