251 research outputs found
Visuospatial exploration and art therapy intervention in patients with Parkinson's disease: an exploratory therapeutic protocol
Abstract Though abnormalities of visuospatial function occur in Parkinson's disease, the impact of such deficits on functional independence and psychological wellbeing has been historically under- recognized, and effective treatments for this impairment are unknown. These symptoms can be encountered at any stage of the disease, affecting many activities of daily living, and negatively influencing mood, self-efficacy, independence, and overall quality of life. Furthermore, visuospatial dysfunction has been recently linked to gait impairment and falls, symptoms that are known to be poor prognostic factors. Here, we aim to present an original modality of neurorehabilitation designed to address visuospatial dysfunction and related symptoms in Parkinson's disease, known as "Art Therapy". Art creation relies on sophisticated neurologic mechanisms including shape recognition, motion perception, sensory-motor integration, abstraction, and eye-hand coordination. Furthermore, art therapy may enable subjects with disability to understand their emotions and express them through artistic creation and creative thinking, thus promoting self-awareness, relaxation, confidence and self-efficacy. The potential impact of this intervention on visuospatial dysfunction will be assessed by means of combined clinical, behavioral, gait kinematic, neuroimaging and eye tracking analyses. Potential favorable outcomes may drive further trials validating this novel paradigm of neurorehabilitation
Deflection and Rotation of CMEs from Active Region 11158
Between the 13 and 16 of February 2011 a series of coronal mass ejections
(CMEs) erupted from multiple polarity inversion lines within active region
11158. For seven of these CMEs we use the Graduated Cylindrical Shell (GCS)
flux rope model to determine the CME trajectory using both Solar Terrestrial
Relations Observatory (STEREO) extreme ultraviolet (EUV) and coronagraph
images. We then use the Forecasting a CME's Altered Trajectory (ForeCAT) model
for nonradial CME dynamics driven by magnetic forces, to simulate the
deflection and rotation of the seven CMEs. We find good agreement between the
ForeCAT results and the reconstructed CME positions and orientations. The CME
deflections range in magnitude between 10 degrees and 30 degrees. All CMEs
deflect to the north but we find variations in the direction of the
longitudinal deflection. The rotations range between 5\mydeg and 50\mydeg with
both clockwise and counterclockwise rotations occurring. Three of the CMEs
begin with initial positions within 2 degrees of one another. These three CMEs
all deflect primarily northward, with some minor eastward deflection, and
rotate counterclockwise. Their final positions and orientations, however,
respectively differ by 20 degrees and 30 degrees. This variation in deflection
and rotation results from differences in the CME expansion and radial
propagation close to the Sun, as well as the CME mass. Ultimately, only one of
these seven CMEs yielded discernible in situ signatures near Earth, despite the
active region facing near Earth throughout the eruptions. We suggest that the
differences in the deflection and rotation of the CMEs can explain whether each
CME impacted or missed the Earth.Comment: 18 pages, 6 figures, accepted in Solar Physic
Homologous Helical Jets: Observations by IRIS, SDO and Hinode and Magnetic Modeling with Data-Driven Simulations
We report on observations of recurrent jets by instruments onboard the
Interface Region Imaging Spectrograph (IRIS), Solar Dynamics Observatory (SDO)
and Hinode spacecrafts. Over a 4-hour period on July 21st 2013, recurrent
coronal jets were observed to emanate from NOAA Active Region 11793. FUV
spectra probing plasma at transition region temperatures show evidence of
oppositely directed flows with components reaching Doppler velocities of +/-
100 km/s. Raster Doppler maps using a Si IV transition region line show all
four jets to have helical motion of the same sense. Simultaneous observations
of the region by SDO and Hinode show that the jets emanate from a source region
comprising a pore embedded in the interior of a supergranule. The parasitic
pore has opposite polarity flux compared to the surrounding network field. This
leads to a spine-fan magnetic topology in the coronal field that is amenable to
jet formation. Time-dependent data-driven simulations are used to investigate
the underlying drivers for the jets. These numerical experiments show that the
emergence of current-carrying magnetic field in the vicinity of the pore
supplies the magnetic twist needed for recurrent helical jet formation.Comment: 15 pages, 10 figures, accepted by Ap
An Interface Region Imaging Spectrograph first view on Solar Spicules
Solar spicules have eluded modelers and observers for decades. Since the
discovery of the more energetic type II, spicules have become a heated topic
but their contribution to the energy balance of the low solar atmosphere
remains unknown. Here we give a first glimpse of what quiet Sun spicules look
like when observed with NASA's recently launched Interface Region Imaging
Spectrograph (IRIS). Using IRIS spectra and filtergrams that sample the
chromosphere and transition region we compare the properties and evolution of
spicules as observed in a coordinated campaign with Hinode and the Atmospheric
Imaging Assembly. Our IRIS observations allow us to follow the thermal
evolution of type II spicules and finally confirm that the fading of Ca II H
spicules appears to be caused by rapid heating to higher temperatures. The IRIS
spicules do not fade but continue evolving, reaching higher and falling back
down after 500-800 s. Ca II H type II spicules are thus the initial stages of
violent and hotter events that mostly remain invisible in Ca II H filtergrams.
These events have very different properties from type I spicules, which show
lower velocities and no fading from chromospheric passbands. The IRIS spectra
of spicules show the same signature as their proposed disk counterparts,
reinforcing earlier work. Spectroheliograms from spectral rasters also confirm
that quiet Sun spicules originate in bushes from the magnetic network. Our
results suggest that type II spicules are indeed the site of vigorous heating
(to at least transition region temperatures) along extensive parts of the
upward moving spicular plasma.Comment: 6 pages, 4 figures, accepted for publication in ApJ Letters. For
associated movies, see http://folk.uio.no/tiago/iris_spic
Detection of supersonic downflows and associated heating events in the transition region above sunspots
IRIS data allow us to study the solar transition region (TR) with an
unprecedented spatial resolution of 0.33 arcsec. On 2013 August 30, we observed
bursts of high Doppler shifts suggesting strong supersonic downflows of up to
200 km/s and weaker, slightly slower upflows in the spectral lines Mg II h and
k, C II 1336 \AA, Si IV 1394 \AA, and 1403 \AA, that are correlated with
brightenings in the slitjaw images (SJIs). The bursty behavior lasts throughout
the 2 hr observation, with average burst durations of about 20 s. The locations
of these short-lived events appear to be the umbral and penumbral footpoints of
EUV loops. Fast apparent downflows are observed along these loops in the SJIs
and in AIA, suggesting that the loops are thermally unstable. We interpret the
observations as cool material falling from coronal heights, and especially
coronal rain produced along the thermally unstable loops, which leads to an
increase of intensity at the loop footpoints, probably indicating an increase
of density and temperature in the TR. The rain speeds are on the higher end of
previously reported speeds for this phenomenon, and possibly higher than the
free-fall velocity along the loops. On other observing days, similar bright
dots are sometimes aligned into ribbons, resembling small flare ribbons. These
observations provide a first insight into small-scale heating events in
sunspots in the TR.Comment: accepted by ApJ
High-resolution Observations of the Shock Wave Behavior for Sunspot Oscillations with the Interface Region Imaging Spectrograph
We present the first results of sunspot oscillations from observations by the
Interface Region Imaging Spectrograph. The strongly nonlinear oscillation is
identified in both the slit-jaw images and the spectra of several emission
lines formed in the transition region and chromosphere. We first apply a single
Gaussian fit to the profiles of the Mgii 2796.35 {\AA}, Cii 1335.71 {\AA}, and
Si iv 1393.76 {\AA} lines in the sunspot. The intensity change is about 30%.
The Doppler shift oscillation reveals a sawtooth pattern with an amplitude of
about 10 km/s in Si iv. In the umbra the Si iv oscillation lags those of Cii
and Mgii by about 3 and 12 s, respectively. The line width suddenly increases
as the Doppler shift changes from redshift to blueshift. However, we
demonstrate that this increase is caused by the superposition of two emission
components. We then perform detailed analysis of the line profiles at a few
selected locations on the slit. The temporal evolution of the line core is
dominated by the following behavior: a rapid excursion to the blue side,
accompanied by an intensity increase, followed by a linear decrease of the
velocity to the red side. The maximum intensity slightly lags the maximum
blueshift in Si iv, whereas the intensity enhancement slightly precedes the
maximum blueshift in Mgii. We find a positive correlation between the maximum
velocity and deceleration, a result that is consistent with numerical
simulations of upward propagating magnetoacoustic shock waves.Comment: 5 figures, in ApJ. Correction of time lags (correct values are 3 and
12s) made on June 17 201
Prevalence of Small-scale Jets from the Networks of the Solar Transition Region and Chromosphere
As the interface between the Sun's photosphere and corona, the chromosphere
and transition region play a key role in the formation and acceleration of the
solar wind. Observations from the Interface Region Imaging Spectrograph reveal
the prevalence of intermittent small-scale jets with speeds of 80-250 km/s from
the narrow bright network lanes of this interface region. These jets have
lifetimes of 20-80 seconds and widths of 300 km or less. They originate from
small-scale bright regions, often preceded by footpoint brightenings and
accompanied by transverse waves with ~20 km/s amplitudes. Many jets reach
temperatures of at least ~100000 K and constitute an important element of the
transition region structures. They are likely an intermittent but persistent
source of mass and energy for the solar wind.Comment: Figs 1-4 & S1-S5; Movies S1-S8; published in Science, including the
main text and supplementary materials. Reference: H. Tian, E. E. DeLuca, S.
R. Cranmer, et al., Science 346, 1255711 (2014
Spatially resolved observations of a split-band coronal type-II radio burst
Context. The origin of coronal type-II radio bursts and of their
band-splitting are still not fully understood. Aims. To make progress in
solving this problem on the basis of one extremely well observed solar eruptive
event. Methods. The relative dynamics of multi-thermal eruptive plasmas,
observed in detail by the SDO/AIA and of the harmonic type-II burst sources,
observed by the NRH at ten frequencies from 445 to 151 MHz, is studied for the
partially behind the limb event on 3 November 2010. Special attention is given
to the band-splitting of the burst. Analysis is supplemented by investigation
of coronal hard X-ray (HXR) sources observed by the RHESSI. Results. It is
found that the flare impulsive phase was accompanied by the formation of a
double coronal HXR source, whose upper part coincided with the hot (T~10 MK)
eruptive plasma blob. The leading edge (LE) of the eruptive plasmas (T~1-2 MK)
moved upward from the flare region with the speed of v=900-1400 km/s. The type
II burst source initially appeared just above the LE apex and moved with the
same speed and in the same direction. After about 20 s it started to move about
twice faster, but still in the same direction. At any given moment the low
frequency component (LFC) source of the splitted type-II burst was situated
above the high frequency component (HFC) source, which in turn was situated
above the LE. It is also found that at a given frequency the HFC source was
located slightly closer to the photosphere than the LFC source. Conclusions.
The shock wave, which could be responsible for the observed type-II radio
burst, was initially driven by the multi-temperature eruptive plasmas, but
later transformed to a freely propagating blast shock wave. The most preferable
interpretation of the type-II burst splitting is that its LFC was emitted from
the upstream region of the shock, whereas the HFC - from the downstream region.Comment: 14 pages, 10 figure
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