The first (M1), second (M2), and third (M3) MESSENGER flybys of Mercury traversed the planet's magnetotail from 1.25 to 3.25 RM downstream of the planet, where RM is Mercury's radius (2440 km). The ...encounters took place under northward, southward, and variable‐polarity interplanetary magnetic field (IMF), respectively. The magnetic field strength B in Mercury's magnetotail follows a power law decrease with increasing antisunward distance ∣X∣, B ∼ ∣X∣G, with G varying from −5.4 for northward to −1.6 for southward IMF. Low‐latitude boundary layers (LLBLs) containing strong northward magnetic field were detected at the tail flanks during two of the flybys. The observed thickness of the LLBL was ∼33% and 16% of the radius of the tail during M1 and M3, respectively, but the boundary layer was completely absent during M2. Clear signatures of tail reconnection are evident in the M2 and M3 magnetic field measurements. Plasmoids and traveling compression regions were observed during M2 and M3 with typical durations of ∼1–3 s, suggesting diameters of ∼500–1500 km. Overall, the response of Mercury's magnetotail to the steady southward IMF during M2 appeared very similar to steady magnetospheric convection events at Earth, which are believed to be driven by quasi‐continuous reconnection. In contrast, the M3 measurements are dominated by tail loading and unloading events that resemble the large‐scale magnetic field reconfigurations observed during magnetospheric substorms at Earth.
Key Points
Mercury's magnetotail resembles that of Earth, but with thicker boundary layers
Mercury exhibits both steady magnetospheric convection and subtorm‐type behavior
Reconnection and plasmoid ejection at Mercury reoccurs with a ~30 s periodicity
Abstract Background There is limited evidence to guide the recognition of patients with massive, uncontrolled hemorrhage who require initiation of a massive transfusion (MT) protocol. Objective To ...risk stratify patients with major trauma and to predict need for MT. Designs Retrospective analysis of an administrative trauma database of major trauma patients. A regional trauma Centre A regional trauma centres in Hong Kong. Patients Patients with Injury Severity Score ≥9 and age ≥12 years were included. Burn patients, patients with known severe anemia and renal failure, or died within 24 h were excluded. Main outcome measures Delivery of ≥10 units of packed red blood cells (RBC) within 24 h. Results Between 01/01/2001 and 30/06/2009, 1891 patients met the inclusion criteria. 92 patients required ≥10 units RBC within 24 h. Seven variables which were easy to be measured in the ED and significantly predicted the need for MT are heart rate ≥120/min; systolic blood pressure ≤90 mmHg; Glasgow coma scale ≤8; displaced pelvic fracture; CT scan or FAST positive for fluid; base deficit >5 mmol/L; hemoglobin ≤7 g/dL; and hemoglobin 7.1–10 g/dL. At a cut off of ≥6, the overall correct classification for predicting need for MT was 96.9%, with a sensitivity of 31.5% and specificity of 99.7%, and an incidence of MT of 82.9%. The area under the curve was 0.889. Conclusion A prediction rule for determining an increased likelihood for the need for massive transfusion has been derived. This needs validation in an independent data set.
The Energetic Particle and Plasma Spectrometer (EPPS) package on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury is composed of two sensors, the ...Energetic Particle Spectrometer (EPS) and the Fast Imaging Plasma Spectrometer (FIPS). EPS measures the energy, angular, and compositional distributions of the high-energy components of the in situ electrons (>20keV) and ions (>5keV/nucleon), while FIPS measures the energy, angular, and compositional distributions of the low-energy components of the ion distributions (<50eV/charge to 20keV/charge). Both EPS and FIPS have very small footprints, and their combined mass (3kg) is significantly lower than that of comparable instruments.
The X‐Ray Spectrometer (XRS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft regularly detected fluorescent X‐rays near Mercury induced by low‐energy (1–10 keV) or ...suprathermal electrons. We devised an algorithm to select these events from XRS records between April 2011 and March 2015 on the basis of their duration, location, and spectral slope. We identified 3102 events during 3900 orbits around Mercury, sampling all Mercury longitudes multiple times over the 4 year period. These suprathermal electrons were present near the planet at all local times, but the majority were on the nightside of the planet, and a dawn‐dusk asymmetry is seen in the data. When the event locations are plotted in a coordinate system based on a simplified magnetic field model, several distinct clusters of events are evident. We infer that all are signatures of accelerated electrons that were injected from Mercury's tail region to form a quasi‐trapped electron population at Mercury.
Key Points
MESSENGER regularly detected suprathermal (<10 keV) electrons from orbit about Mercury
The majority of these electrons were clustered near Mercury's magnetic equator
Accelerated electrons are injected from Mercury's tail to form a quasi‐trapped population
The aim of this study was to investigate the effects of a natural component, theissenolactone C (LC53), on the ocular inflammation of experimental endotoxin-induced uveitis (EIU) and its related ...mechanisms in microglia. Evaluation of the severity of anterior uveitis indicated that LC53 treatment significantly decreased iridal hyperemia and restored the clinical scores. Additionally, the deficient retina functions of electroretinography were improved by LC53. LC53 significantly reduced levels of tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1, protein leakage and activation of matrix metalloproteinases in the anterior section during EIU. Moreover, LC53 treatment decreased the oxidative stress as well as neuroinflammatory reactivities of GFAP and Iba-1 in the posterior section. Furthermore, LC53 decreased the phosphorylation of p65, expression of HSP90, Bax, and cleaved-caspase-3 in EIU. According to the microglia studies, LC53 significantly abrogated the productions of TNF-α, PGE
, NO and ROS, as well as inducible NO synthase and cyclooxygenase-2 expression in LPS-stimulated microglial BV2 cells. The microglial activation of IKKβ, p65 phosphorylation and nuclear phosphorylated p65 translocation were strongly attenuated by LC53. On the other hand, LC53 exhibited the inhibitory effects on JNK and ERK MAPKs activation. Our findings indicated that LC53 exerted the ocular-protective effect through its inhibition on neuroinflammation, glial activation, and apoptosis in EIU, suggesting a therapeutic potential with down-regulation of the NF-κB signaling for uveitis and retinal inflammatory diseases.
Mercury's Magnetosphere After MESSENGER's First Flyby Slavin, James A; Acuña, Mario H; Anderson, Brian J ...
Science (American Association for the Advancement of Science),
07/2008, Letnik:
321, Številka:
5885
Journal Article
Recenzirano
Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na⁺, is broadly distributed but exhibits flux maxima in the ...magnetosheath, where the local plasma flow speed is high, and near the spacecraft's closest approach, where atmospheric density should peak. The magnetic field showed reconnection signatures in the form of flux transfer events, azimuthal rotations consistent with Kelvin-Helmholtz waves along the magnetopause, and extensive ultralow-frequency wave activity. Two outbound current sheet boundaries were observed, across which the magnetic field decreased in a manner suggestive of a double magnetopause. The separation of these current layers, comparable to the gyro-radius of a Na⁺ pickup ion entering the magnetosphere after being accelerated in the magnetosheath, may indicate a planetary ion boundary layer.
Birth defects result from interactions between genetic and environmental factors, but the mechanisms remain poorly understood. We find that mutations and teratogens interact in predictable ways to ...cause birth defects by changing target cell sensitivity to Hedgehog (Hh) ligands. These interactions converge on a membrane protein complex, the MMM complex, that promotes degradation of the Hh transducer Smoothened (SMO). Deficiency of the MMM component MOSMO results in elevated SMO and increased Hh signaling, causing multiple birth defects. In utero exposure to a teratogen that directly inhibits SMO reduces the penetrance and expressivity of birth defects in Mosmo-/- embryos. Additionally, tissues that develop normally in Mosmo-/- embryos are refractory to the teratogen. Thus, changes in the abundance of the protein target of a teratogen can change birth defect outcomes by quantitative shifts in Hh signaling. Consequently, small molecules that re-calibrate signaling strength could be harnessed to rescue structural birth defects.
The X‐Ray Spectrometer (XRS) on the MESSENGER spacecraft measures elemental abundances on the surface of Mercury by detecting fluorescent X‐ray emissions induced on the planet's surface by the ...incident solar X‐ray flux. The XRS began orbital observations on 23 March 2011 and has observed X‐ray fluorescence (XRF) from the surface of the planet whenever a sunlit portion of Mercury has been within the XRS field of view. Solar flares are generally required to provide sufficient signal to detect elements that fluoresce at energies above ∼2 keV, but XRF up to the calcium line (3.69 keV) has been detected from Mercury's surface at times when the XRS field of view included only unlit portions of the planet. Many such events have been detected and are identified as electron‐induced X‐ray emission produced by the interaction of ∼1–10 keV electrons with Mercury's surface. Electrons in this energy range were detected by the XRS during the three Mercury flybys and have also been observed regularly in orbit about Mercury. Knowledge of the energy spectrum of the electrons precipitating at the planet's surface makes it possible to infer surface composition from the measured fluorescent spectra, providing additional measurement opportunities for the XRS. Abundance results for Mg, Al, and Si are in good agreement with those derived from solar‐induced XRF data, providing independent validation of the analysis methodologies. Derived S and Ca abundances are somewhat higher than derived from the solar‐induced fluorescence data, possibly reflecting incomplete knowledge of the energy spectra of electrons impacting the planet.
Key Points
Electron induced XRF detected from Mercury's surface
Exciting electron spectrum known from model
Surface elemental abundances inferred from detected XRF
Correction to: Solar Phys (2019) 294:33
https://doi.org/10.1007/s11207-019-1420-z
The original article has been corrected due to typesetting mistakes made in the last paragraph of section
2. ...Observations.
We investigated
3
He-rich solar energetic particle (SEP) events in the current solar cycle starting in 2009 through 2017. Both “impulsive” (flare-related)
3
He-rich and CME-related “gradual” events ...are included. In the former solar cycle, we found the number of observed
3
He-rich events correlated with solar activity. The same correlation is seen again in Cycle 24. Because of the comparatively weak activity, both the occurrence of
3
He-rich events and their intensities are significantly less than those from Cycle 23. Interestingly, we found in several of the
3
He-rich events that there is no measurable
4
He intensity increase above the instrument background. Previously, we found that there is a limit on the number of
3
He ions that can be released from the Sun in an impulsive SEP event, while there is no such limit on the
4
He ions (Ho, Roelof, and Mason in
Astrophys. J
.,
621
, L862,
2005
). In this paper, we examine several of these
3
He-rich events in detail and discuss the lack of observable
4
He intensity increases and the implications for the enhancement and acceleration mechanism of this special type of SEP events.
PDF
