268 research outputs found
A mixed-methods exploration of virtual reality as a tool to promote green exercise
The salutogenic effects of green exercise are widely recognised, yet many individuals do not engage in this health-related behaviour. Using a convergent mixed methods approach, this study explored the impact of Virtual Reality (VR) mediated nature exposure on the decision-making process relating to green exercise. Three experimental trials were conducted (overall n = 136), in which healthy adults were exposed to different VR scenarios reproducing a virtual walk in an existing urban green area. Participants reported medium-high rating of intent to visit the location. Significant pre-to-post increments in future green exercise intention were observed after the VR exposure, though a significance difference was not achieved in comparison with a control condition. Qualitative analysis revealed the impact of the VR experience on behaviour regulation, and highlighted the pivotal role of anticipated emotional benefits. Despite scepticism, the VR experience was effective in arousing curiosity to explore natural environments, which was associated with environmental perceptions, nostalgic and socio-cultural perspectives.submittedVersionacceptedVersio
Agonistic Games: Multiperspective and Unsettling Games for a Social Change
Historical narratives of conflict typically revolve around heroes and villains or perpetrators and victims. However, this dichotomy of events and people into good and evil greatly reduces the extent to which the past can be analysed, explained, and understood.To truly understand the actions that lead to conflict, one must appreciate the dense network of relationships between social agents, each with their own personal motivations and ideals. A contemporary political viewpoint capturing this multiperspectivity is that of Agonism. Focusing on the characters and events, Agonism emphasises the socio-cultural interactions and relationships between all agents involved including bystanders and, crucially, perpetrators. We discuss two `Games for a Social Change' that we have developed to promote an Agonistic view: Endless Blitz and Umschlagplatz '43. We describe the games themselves, and the framework of memory studies that informs our work
Turning round the telescope. Centre-right parties and immigration and integration policy in Europe
This is an Author's Original Manuscript of 'Turning round the telescope. Centre-right parties and immigration and integration policy in Europe', whose final and definitive form, the Version of Record, has been published in the Journal of European Public Policy 15(3):315-330, 2008 [copyright Taylor & Francis], available online at: http://www.tandfonline.com/doi.org/10.1080/13501760701847341
Interacting coronae of two T Tauri stars: first observational evidence for solar-like helmet streamers
Context {The young binary system V773 Tau A exhibits a persistent radio
flaring activity that gradually increases from a level of a few mJy at
apoastron to more than 100 mJy at periastron. Interbinary collisions between
very large (> 15 R) magnetic structures anchored on the two rotating stars of
the system have been proposed to be the origin of these periodic radio flares.
Magnetic structures extended over tens of stellar radii, that can also account
for the observed fast decay of the radio flares, seem to correspond to the
typical solar semi-open quite extended magnetic configurations called helmet
streamers.} Aims {We aim to find direct observational evidence for the
postulated, solar-like, coronal topologies.} Methods {We performed
seven-consecutive-day VLBI observations at 8.4 GHz using an array consisting of
the VLBA and the 100-m Effelsberg telescope.} Results {Two distintive
structures appear in the radio images here presented. They happen to be
associated with the primary and secondary stars of the V773 Tau A system. In
one image (Fig.2-B) the two features are extended up to 18 R each and are
nearly parallel revealing the presence of two interacting helmet streamers. One
image (Fig.2-E) taken a few hours after a flare monitored by the 100-m
Effelsberg telescope shows one elongated fading structure substantially rotated
with respect to those seen in the B run. The same decay scenario is seen in
Fig.2-G for the helmet streamer associated with the other star.} Conclusions
{This is the very first direct evidence revealing that even if the flare origin
is magnetic reconnection due to interbinary collision, both stars independently
emit in the radio range with structures of their own. These structures are
helmet streamers, observed for the first time in stars other than the Sun.}Comment: 7 pages, 3 figures, A&A in pres
Radial velocities of early-type stars in the Perseus OB2 association
We present radial velocities for 29 B- and A-type stars in the field of the
nearby association Perseus OB2. The velocities are derived from spectra
obtained with AURELIE, via cross correlation with radial velocity standards
matched as closely as possible in spectral type. The resulting accuracy is ~2 -
3 km s. We use these measurements, together with published values for a
few other early-type stars, to study membership of the association. The mean
radial velocity (and measured velocity dispersion) of Per OB2 is 23.5 \pm 3.9
km s, and lies ~15 km s away from the mean velocity of the local
disk field stars. We identify a number of interlopers in the list of possible
late-B- and A-type members which was based on Hipparcos parallaxes and proper
motions, and discuss the colour-magnitude diagram of the association.Comment: 20 pages, 9 figures, accepted for publication in A&A, minor revision
The model of dynamo with small number of modes and magnetic activity of T Tauri stars
The model that describes operation of dynamo in fully convective stars is
presented. It is based on representation of stellar magnetic field as a
superposition of finite number of poloidal and toroidal free damping modes. In
the frame of adopted low of stellar differential rotation we estimated minimal
value of dynamo number D, starting from which generation of cyclic magnetic
field in stars without radiative core is possible. We also derived expression
for period of the cycle. It was found that dynamo cycles of fully convective
stars and stars with thin convective envelopes differ in a qualitative way: 1)
distribution of spots over latitude during the cycle is different in these
stars; 2) the model predicts that spot formation in fully convective stars
should be strongly suppressed at some phases of the cycle.
We have analyzed historical lightcurve of WTTS star V410 Tau and found that
long term activity of the star is not periodic process. Rather one can speak
about quasi cyclic activity with characteristic time of yr and chaotic
component over imposed. We concluded also that redistribution of cool spots
over longitude is the reason of long term variations of V410 Tau brightness. It
means that one can not compare directly results of photometric observations
with predictions of our axially symmetric (for simplicity) model which allows
to investigate time evolution of spot's distribution over latitude. We then
discuss what kind of observations and in which way could be used to check
predictions of the dynamo theory.Comment: 18 pages, 5 figures, accepted to Astron. Let
Immigration into the mainstream: Conflicting ideological streams, strategic reasoning and party competition
Mid-IR Observations of T Tauri stars: Probing the Star-Disk Connection in Rotational Evolution
We present mid-IR N-band (\lambda_{eff} = 10.2\micron) photometry of a
carefully selected sample of T Tauri stars thought to be single from the
Taurus-Auriga molecular cloud. Infrared excesses in these stars are generally
attributed to circumstellar dust-disks. Combining observations at 2.16\micron
(K-band) and 10.2\micron (N-band) we probe a region in the
circumstellar dust-disk from a few stellar radii through the terrestrial planet
zone (0.02-1.0AU). By analyzing the distribution of the color index
with respect to previously measured photometric rotation periods we investigate
what role circumstellar disks play in the rotational evolution of the central
star. The resulting positive correlation between these two variables is
consistent with the notion that a star-disk interaction facilitates the
regulation of angular momentum during the T Tauri stage. We also demonstrate,
how including non-single stars in such an analysis will \textit{weaken} any
correlation in the relation between color and period. To further
understand disk properties we also present SEDs for a few objects with new
ground based M-band (\lambda_{eff} = 4.8\micron) and Q-band (\lambda_{eff} =
20\micron) data and compare them to a geometrically thin, optically-thick disk
model.Comment: 9 pages, 4 figure
The absence of sub-minute periodicity in classical T Tauri stars
Classical T Tauri stars (CTTS) are young, late-type objects, that still
accrete matter from a circumstellar disk. Analytical treatments and numerical
simulations predict instabilities of the accretion shock on the stellar
surface. We search for variability on timescales below a few minutes in the
CTTS TW Hya and AA Tau. TW Hya was observed with SALTICAM on the Southern
African Large Telescope (SALT) in narrow-band filters around the Balmer jump.
The observations were performed in slit mode, which provides a time resolution
of about 0.1 s. For AA Tau we obtained observations with OPTIMA, a single
photon-counting device with even better time resolution. Small-scale
variability typically lasts a few seconds, however, no significant periodicity
is detected. We place a 99 % confidence upper limit on the pulsed fraction of
the lightcurves. The relative amplitude is below 0.001 for TW Hya in the
frequency range 0.02-3 Hz in the 340 nm filter and 0.1-3 Hz in the 380 nm
filter. The corresponding value for AA Tau is an amplitude of 0.005 for 0.02-50
Hz. The relevant timescales indicate that shock instabilites should not be seen
directly in our optical and UV observations, but the predicted oscialltions
would induce observable variations in the reddening. We discuss how the
magnetic field could stabilise the accretion shock.Comment: 8 pages, 9 figures, accepted by A&
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