1,898 research outputs found
Morphology and density of post-CME current sheets
Eruption of a coronal mass ejection (CME) drags and "opens" the coronal
magnetic field, presumably leading to the formation of a large-scale current
sheet and the field relaxation by magnetic reconnection. We analyze physical
characteristics of ray-like coronal features formed in the aftermath of CMEs,
to check if the interpretation of this phenomenon in terms of reconnecting
current sheet is consistent with the observations. The study is focused on
measurements of the ray width, density excess, and coronal velocity field as a
function of the radial distance. The morphology of rays indicates that they
occur as a consequence of Petschek-like reconnection in the large scale current
sheet formed in the wake of CME. The hypothesis is supported by the flow
pattern, often showing outflows along the ray, and sometimes also inflows into
the ray. The inferred inflow velocities range from 3 to 30 km s,
consistent with the narrow opening-angle of rays, adding up to a few degrees.
The density of rays is an order of magnitude larger than in the ambient corona.
The density-excess measurements are compared with the results of the analytical
model in which the Petschek-like reconnection geometry is applied to the
vertical current sheet, taking into account the decrease of the external
coronal density and magnetic field with height. The model results are
consistent with the observations, revealing that the main cause of the density
excess in rays is a transport of the dense plasma from lower to larger heights
by the reconnection outflow
Calcitonin gene-related peptide promotes cellular changes in trigeminal neurons and glia implicated in peripheral and central sensitization
<p>Abstract</p> <p>Background</p> <p>Calcitonin gene-related peptide (CGRP), a neuropeptide released from trigeminal nerves, is implicated in the underlying pathology of temporomandibular joint disorder (TMD). Elevated levels of CGRP in the joint capsule correlate with inflammation and pain. CGRP mediates neurogenic inflammation in peripheral tissues by increasing blood flow, recruiting immune cells, and activating sensory neurons. The goal of this study was to investigate the capability of CGRP to promote peripheral and central sensitization in a model of TMD.</p> <p>Results</p> <p>Temporal changes in protein expression in trigeminal ganglia and spinal trigeminal nucleus were determined by immunohistochemistry following injection of CGRP in the temporomandibular joint (TMJ) capsule of male Sprague-Dawley rats. CGRP stimulated expression of the active forms of the MAP kinases p38 and ERK, and PKA in trigeminal ganglia at 2 and 24 hours. CGRP also caused a sustained increase in the expression of c-Fos neurons in the spinal trigeminal nucleus. In contrast, levels of P2X<sub>3 </sub>in spinal neurons were only significantly elevated at 2 hours in response to CGRP. In addition, CGRP stimulated expression of GFAP in astrocytes and OX-42 in microglia at 2 and 24 hours post injection.</p> <p>Conclusions</p> <p>Our results demonstrate that an elevated level of CGRP in the joint, which is associated with TMD, stimulate neuronal and glial expression of proteins implicated in the development of peripheral and central sensitization. Based on our findings, we propose that inhibition of CGRP-mediated activation of trigeminal neurons and glial cells with selective non-peptide CGRP receptor antagonists would be beneficial in the treatment of TMD.</p
A Statistical Study on the Morphology of Rays and Dynamics of Blobs in the Wake of Coronal Mass Ejections
In this paper, with a survey through the Large Angle and Spectrometric
Coronagraph (LASCO) data from 1996 to 2009, we present 11 events with plasma
blobs flowing outwards sequentially along a bright coronal ray in the wake of a
coronal mass ejection. The ray is believed to be associated with the current
sheet structure that formed as a result of solar eruption, and the blobs are
products of magnetic reconnection occurring along the current sheet. The ray
morphology and blob dynamics are investigated statistically. It is found that
the apparent angular widths of the rays at a fixed time vary in a range of
2.1-6.6 (2.0-4.4) degrees with an average of 3.5 (2.9) degrees at 3 (4) Rs,
respectively, and the observed durations of the events vary from 12 h to a few
days with an average of 27 h. It is also found, based on the analysis of blob
motions, that 58% (26) of the blobs were accelerated, 20% (9) were decelerated,
and 22% (10) moved with a nearly-constant speed. Comparing the dynamics of our
blobs and those that are observed above the tip of a helmet streamer, we find
that the speeds and accelerations of the blobs in these two cases differ
significantly. It is suggested that these differences of the blob dynamics stem
from the associated magnetic reconnection involving different magnetic field
configurations and triggering processes.Comment: 12 pages, 6 figures, accepted by Solar Physic
Real Time Animation of Virtual Humans: A Trade-off Between Naturalness and Control
Virtual humans are employed in many interactive applications using 3D virtual environments, including (serious) games. The motion of such virtual humans should look realistic (or ‘natural’) and allow interaction with the surroundings and other (virtual) humans. Current animation techniques differ in the trade-off they offer between motion naturalness and the control that can be exerted over the motion. We show mechanisms to parametrize, combine (on different body parts) and concatenate motions generated by different animation techniques. We discuss several aspects of motion naturalness and show how it can be evaluated. We conclude by showing the promise of combinations of different animation paradigms to enhance both naturalness and control
Magnetic Reconnection with Asymmetry in the Outflow Direction
Magnetic reconnection with asymmetry in the outflow direction occurs in the
Earth's magnetotail, coronal mass ejections, flux cancellation events,
astrophysical disks, spheromak merging experiments, and elsewhere in nature and
the laboratory. A control volume analysis is performed for the case of steady
antiparallel magnetic reconnection with asymmetric downstream pressure, which
is used to derive scaling relations for the outflow velocity from each side of
the current sheet and the reconnection rate. Simple relationships for outflow
velocity are presented for the incompressible case and the case of symmetric
downstream pressure but asymmetric downstream density. Asymmetry alone is not
found to greatly affect the reconnection rate. The flow stagnation point and
magnetic field null do not coincide in a steady state unless the pressure
gradient is negligible at the flow stagnation point.Comment: 12 pages, 8 figures. Submitted to JGR. Any comments will be
appreciate
The Utility of Multi-detector Row Spiral CT for Detection of Coronary Artery Stenoses
Contrast-enhanced multi-detector row spiral computed tomography (MDCT) was introduced as a promising noninvasive method for vascular imaging. This study examined the accuracy of this technique for detecting significant coronary artery stenoses. Both MDCT(Sensation 16, Siemens, Germany, 12 × 0.75 mm collimation and 0.42 sec rotation speed, 120 kV, 500 effective mA, and 2.7 mm/rotation table-feed) and invasive coronary angiography (CAG) were performed on 61 patients (mean age 59.2 ± 10, 44 men) who were suspected of having coronary artery disease. All patients were treated with atenolol (25 - 50 mg) prior to imaging and the heart rate was maintained below 65 beats per minutes during image acquisition. The images were reconstructed in the diastole around TI - 400 ms with a 0.5 mm increment and a 1.0 mm thickness. All coronary arteries with a diameter of 2.0 mm or more were assessed for the presence of a stenosis (> 50% luminal narrowing). Two independent radiologists who were unaware of the results of the invasive CAG evaluated the MDCT data, and the results were compared with those from the invasive CAG (interval 1- 27, mean 11 days). An evaluation of the CT coronary angiogram (CTCA) was possible in 58 of the 61 patients (95%). Image acquisition of the major coronary arteries including the left main trunk was available in 229 out of 244 arteries. Invasive CAG showed that 35 out of 58 patients had significant coronary artery stenoses by. patient analysis of those who could be evaluated showed that CT coronary angiography correctly classified 30 out of 35 patients as having at least 1 coronary stenosis (sensitivity 85.7%, specificity 91.3%, positive predictive value 93.8%, negative predictive value 80.8%). By analyzing each coronary artery, CAG found 62 stenotic coronary arteries in the 229 coronary arteries that could be evaluated. MDCT correctly detected 50 out of 62 stenotic coronary arteries and an absence of stenosis was correctly identified in 156 out of 167 normal coronary arteries (sensitivity 80.6%, specificity 93.4%, positive predictive value 81.9%, negative predictive value 92.8%). The non-invasive technique of MDCT for examining the coronary artery appears to be a useful method for detecting coronary artery stenoses with a high accuracy particularly with the proximal portion and large arteries
Plasmoids in Reconnecting Current Sheets: Solar and Terrestrial Contexts Compared
Magnetic reconnection plays a crucial role in violent energy conversion
occurring in the environments of high electrical conductivity, such as the
solar atmosphere, magnetosphere, and fusion devices. We focus on the
morphological features of the process in two different environments, the solar
atmosphere and the geomagnetic tail. In addition to indirect evidence that
indicates reconnection in progress or having just taken place, such as auroral
manifestations in the magnetosphere and the flare loop system in the solar
atmosphere, more direct evidence of reconnection in the solar and terrestrial
environments is being collected. Such evidence includes the reconnection inflow
near the reconnecting current sheet, and the outflow along the sheet
characterized by a sequence of plasmoids. Both turbulent and unsteady
Petschek-type reconnection processes could account for the observations. We
also discuss other relevant observational consequences of both mechanisms in
these two settings. While on face value, these are two completely different
physical environments, there emerge many commonalities, for example, an Alfven
speed of the same order of magnitude, a key parameter determining the
reconnection rate. This comparative study is meant as a contribution to current
efforts aimed at isolating similarities in processes occurring in very
different contexts in the heliosphere, and even in the universe.Comment: 21 pages, 9 figures, in press at J. Geophys. Res. (Space Physics),
for the special NESSC section on Comparative Aspects of Magnetic Reconnectio
Model-Independent Short-Baseline Oscillations from Reactor Spectral Ratios
We consider the ratio of the spectra measured in the DANSS neutrino
experiment at 12.7 and 10.7~m from a nuclear reactor. These data give a new
model-independent indication in favor of short-baseline
oscillations which reinforce the model-independent indication found in the late
2016 in the NEOS experiment. The combined analysis of the NEOS and DANSS
spectral ratios in the framework of 3+1 active-sterile neutrino mixing favor
short-baseline oscillations with a statistical significance of
. The two mixing parameters and
are constrained at in a
narrow- island at , with ().
We discuss the implications of the model-independent NEOS+DANSS analysis for
the reactor and Gallium anomalies. The NEOS+DANSS model-independent
determination of short-baseline oscillations allows us to analyze
the reactor rates without assumptions on the values of the main reactor
antineutrino fluxes and the data of the Gallium source experiments with free
detector efficiencies. The corrections to the reactor neutrino fluxes and the
Gallium detector efficiencies are obtained from the fit of the data. In
particular, we confirm the indication in favor of the need for a recalculation
of the reactor antineutrino flux found in previous studies
assuming the absence of neutrino oscillations.Comment: 10 pages; analysis improved by taking into account the uncertainties
of the reactor fission fraction
Assessment of the Type D Personality Construct in the Korean Population: A Validation Study of the Korean DS14
This study aimed to develop a Korean version of the Type D Personality Scale-14 (DS14) and evaluate the psychiatric symptomatology of Korean cardiac patients with Type D personality. Healthy control (n = 954), patients with a coronary heart disease (n = 111) and patients with hypertension and no heart disease (n = 292) were recruited. All three groups completed DS14, the Eysenck Personality Questionnaire (EPQ), the state subscale of Spielberger State and Trait Anxiety Inventory (STAI-S), the Center for Epidemiologic Studies Short Depression Scale (CESD), and the General Health Questionnaire (GHQ). The Korean DS14 was internally consistent and stable over time. 27% of the subjects were classified as Type D. Type D individuals had significantly higher mean scores on the STAI-S, CESD, and GHQ compared to non-Type D subjects in each group. The Korean DS14 was a valid and reliable tool for identifying Type D personality. The general population and cardiovascular patients with Type D personality showed higher rate of depression, anxiety and psychological distress regarding their health. Therefore, identifying Type D personality is important in clinical research and practice in chronic medical disorders, especially cardiovascular disease, in Korea
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