781 research outputs found
Influence of NLTE effects in Fe I lines on inverted atmosphere II. 6301 A and 6302 A lines formed in 3DNLTE
This paper forms the second part of our study on how the neglect of NLTE
conditions in the formation of Fe I 6301.5 A and the 6302.5 A lines influences
the atmosphere obtained by inverting their profiles in LTE. The main cause of
NLTE effects is the line opacity deficit due to the excess ionization of the Fe
I atoms by the UV photons in the Sun. In the first paper, the above
photospheric lines were assumed to have formed in 1DNLTE and the effects of
horizontal radiation transfer (RT) were neglected. In the present paper, the
iron lines are computed in 3DNLTE. We investigate the influence of horizontal
RT on the inverted atmosphere and how it can enhance or reduce the errors due
to the neglect of 1DNLTE effects. The iron lines are computed in LTE, 1DNLTE
and 3DNLTE. They all are inverted using an LTE inversion code. The atmosphere
from the inversion of LTE profiles is taken as the reference model. The test
atmospheres from the inversion of 1DNLTE and 3DNLTE profiles are compared with
it. The differences between models are analysed and correspondingly attributed
to NLTE and 3D effects. The effects of horizontal RT are evident in regions
surrounded by strong horizontal gradients in temperature. In some regions, the
3D effects enhance the 1DNLTE effects while in some, they weaken. The errors
due to neglecting the 3D effects are less than 5% in temperature while the
errors are mostly less than 20% in both velocity and magnetic field strength.
These errors are found to survive spatial and spectral degradation. The neglect
of horizontal RT is found to introduce errors in the derived atmosphere. How
large the errors are depends on how strong the local horizontal gradients are
in temperature. Compared to the 1DNLTE effect, the 3D effects are more
localised to specific regions in the atmosphere and overall less dominant.Comment: Accepted for publication in A&A. Abstract abridged for arxiv
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Isolation of the Two Monoferric Human Transferrins by Preparative Isoelectric Focussing
Peer Reviewe
Constant force muscle stretching induces greater acute deformations and changes in passive mechanical properties compared to constant length stretching
Stretching is applied to lengthen shortened muscles in pathological conditions such as joint contractures. We investigated (i) the acute effects of different types of stretching, i.e. constant length (CL) and constant force (CF) stretching, on acute deformations and changes in passive mechanical properties of medial gastrocnemius muscle (MG) and (ii) the association of acute muscle–tendon deformations or changes in mechanical properties with the impulse or maximal strain of stretching. Forty-eight hindlimbs from 13 male and 12 female Wistar rats (13 weeks old, respectively 424.6 ± 35.5 and 261.8 ± 15.6 g) were divided into six groups (n = 8 each). The MG was initially stretched to a length at which the force was 75%, 95%, or 115% of the force corresponding to estimated maximal dorsiflexion and held at either CF or CL for 30 min. Before and after the stretching protocol, the MG peak force and peak stiffness were assessed by lengthening the passive muscle to the length corresponding to maximal ankle dorsiflexion. Also, the muscle belly length and tendon length were measured. CF stretching affected peak force, peak stiffness, muscle belly length, and tendon length more than CL stretching (p < 0.01). Impulse was associated only with the decrease in peak force, while maximal strain was associated with the decrease in peak force, peak stiffness, and the increase in muscle belly length. We conclude that CF stretching results in greater acute deformations and changes in mechanical properties than CL stretching, which appears to be dependent predominantly on the differences in imposed maximal strain.</p
Magnetoacoustic shocks as driver of quiet Sun mottles
We present high spatial and high temporal resolution observations of the
quiet Sun in H-alpha obtained with the Swedish 1-m Solar Telescope on La Palma.
We observe that many mottles, jet-like features in the quiet Sun, display clear
up- and downward motions along their main axis. In addition, many mottles show
vigorous transverse displacements. Unique identification of the mottles
throughout their lifetime is much harder than for their active region
counterpart, dynamic fibrils. This is because many seem to lack a sharply
defined edge at their top, and significant fading often occurs throughout their
lifetime. For those mottles that can be reliably tracked, we find that the
mottle tops often undergo parabolic paths. We find a linear correlation between
the deceleration these mottles undergo and the maximum velocity they reach,
similar to what was found earlier for dynamic fibrils. Combined with an
analysis of oscillatory properties, we conclude that at least part of the quiet
Sun mottles are driven by magnetoacoustic shocks. In addition, the mixed
polarity environment and vigorous dynamics suggest that reconnection may play a
significant role in the formation of some quiet Sun jets.Comment: 12 pages, 4 figures. ApJ Letters, in pres
The effect of prophylactic cranial irradiation (PCI) for young stage III NSCLC patients:Subgroup analyses of the NVALT-11/DLCRG-02 study
Small heat shock proteins are induced during multiple sclerosis lesion development in white but not grey matter
INTRODUCTION: The important protective role of small heat-shock proteins (HSPs) in regulating cellular survival and migration, counteracting protein aggregation, preventing apoptosis, and regulating inflammation in the central nervous system is now well-recognized. Yet, their role in the neuroinflammatory disorder multiple sclerosis (MS) is largely undocumented. With the exception of alpha B-crystallin (HSPB5), little is known about the roles of small HSPs in disease. RESULTS: Here, we examined the expression of four small HSPs during lesion development in MS, focussing on their cellular distribution, and regional differences between white matter (WM) and grey matter (GM). It is well known that MS lesions in these areas differ markedly in their pathology, with substantially more intense blood-brain barrier damage, leukocyte infiltration and microglial activation typifying WM but not GM lesions. We analysed transcript levels and protein distribution profiles for HSPB1, HSPB6, HSPB8 and HSPB11 in MS lesions at different stages, comparing them with normal-appearing brain tissue from MS patients and non-neurological controls. During active stages of demyelination in WM, and especially the centre of chronic active MS lesions, we found significantly increased expression of HSPB1, HSPB6 and HSPB8, but not HSPB11. When induced, small HSPs were exclusively found in astrocytes but not in oligodendrocytes, microglia or neurons. Surprisingly, while the numbers of astrocytes displaying high expression of small HSPs were markedly increased in actively demyelinating lesions in WM, no such induction was observed in GM lesions. This difference was particularly obvious in leukocortical lesions covering both WM and GM areas. CONCLUSIONS: Since induction of small HSPs in astrocytes is apparently a secondary response to damage, their differential expression between WM and GM likely reflects differences in mediators that accompany demyelination in either WM or GM during MS. Our findings also suggest that during MS, cortical structures fail to benefit from the protective actions of small HSPs. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40478-015-0267-2) contains supplementary material, which is available to authorized users
Kinematics of Magnetic Bright Features in the Solar Photosphere
Convective flows are known as the prime means of transporting magnetic fields
on the solar surface. Thus, small magnetic structures are good tracers of the
turbulent flows. We study the migration and dispersal of magnetic bright
features (MBFs) in intergranular areas observed at high spatial resolution with
Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion
process whose parameters are computed for various areas in the quiet Sun and
the vicinity of active regions from seeing-free data. We find that magnetic
concentrations are best described as random walkers close to network areas
(diffusion index, gamma=1.0), travelers with constant speeds over a
supergranule (gamma=1.9-2.0), and decelerating movers in the vicinity of flux
emergence and/or within active regions (gamma=1.4-1.5). The three types of
regions host MBFs with mean diffusion coefficients of 130 km^2/s, 80-90 km^2/s,
and 25-70 km^2/s, respectively. The MBFs in these three types of regions are
found to display a distinct kinematic behavior at a confidence level in excess
of 95%.Comment: 8 pages, 4 figure
Solar Coronal Loops Associated with Small-scale Mixed Polarity Surface Magnetic Fields
How and where are coronal loops rooted in the solar lower atmosphere? The
details of the magnetic environment and its evolution at the footpoints of
coronal loops are crucial to understanding the processes of mass and energy
supply to the solar corona. To address the above question, we use
high-resolution line-of-sight magnetic field data from the Imaging Magnetograph
eXperiment instrument on the SUNRISE balloon-borne observatory and coronal
observations from the Atmospheric Imaging Assembly onboard the Solar Dynamics
Observatory of an emerging active region. We find that the coronal loops are
often rooted at the locations with minor small-scale but persistent
opposite-polarity magnetic elements very close to the larger dominant polarity.
These opposite-polarity small-scale elements continually interact with the
dominant polarity underlying the coronal loop through flux cancellation. At
these locations we detect small inverse Y-shaped jets in chromospheric Ca II H
images obtained from the SUNRISE Filter Imager during the flux cancellation.
Our results indicate that magnetic flux cancellation and reconnection at the
base of coronal loops due to mixed polarity fields might be a crucial feature
for the supply of mass and energy into the corona.Comment: Published in the Astrophysical Journal Supplement Serie
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