232 research outputs found
Numerical Simulations of Solar Chromospheric Jets Associated with Emerging Flux
We studied the acceleration mechanisms of chromospheric jets associated with
emerging flux using a two dimensional magnetohydrodynamic (MHD) simulation. We
found that slow mode shock waves generated by magnetic reconnection in the
chromosphere and the photosphere play key roles in the acceleration mechanisms
of chromospheric jets. An important parameter is the height of magnetic
reconnection. When magnetic reconnection takes place near the photosphere, the
reconnection out- flow collides with the region where the plasma beta is much
larger than unity. Then the plasma moves along a magnetic field. This motion
generates a slow mode wave. The slow mode wave develops to a strong slow shock
as it propagates upward. When the slow shock crosses the transition region, the
transition region is lifted up. As a result, we obtain a chromospheric jet as
the lifted transition region. When magnetic reconnection takes place in the
upper chromosphere, the chromospheric plasma is accelerated due to the
combination of the Lorentz force and the whip-like motion of magnetic field. We
found that the chromospheric plasma is further accelerated through the
interaction between the transition region (steep density gradient) and a slow
shock emanating from the reconnection point. This is an MHD effect which has
not been discussed before.Comment: PASJ, accepted, 39 pages, 23 figure
TROPHODYNAMIC ACCUMULATION OF BROMINATED FLAME RETARDANTS IN BIOTA OF JAKARTA BAY
The level of contamination, bioaccumulation and potential trophic transfer of toxic pollutants known as brominated flame retardants (BFRs), such as polybrominated diphenyl ethers (PBDEs) and hexabromocychlododecanes (HBCDs), was examined in biota representing different trophic levels in Jakarta Bay. Various organisms were collected using several catching methods during July-August 2007 at eastern part of the bay and were analyzed for nitrogen (N) and carbon (C) stable isotopes, 14 PBDE congeners and three HBCD isomers using GC-C-IRMS, GC-MS and LC-MS/MS, respectively. Analysis of N and C indicated that the biota was composed by different trophic levels within the Jakarta Bay ecosystem. Concentrations of total PBDEs and total HBCDs varied according to species, ranged from 1.6 ng/g lipid wt. to 57 ng/g lipid wt. and below detection limit (nd) to 4.1 ng/g lipid wt, respectively. Furthermore, there was significant positive correlation between trophic level (TL) and concentration of PBDEs was found, but not HBCDs. Trophic Magnification Factors (TMF) values of PBDEs ranged 0.63–3.0 with only two congeners (BDE-47 and BDE–100) having TMFs greater than one
Strongly Blueshifted Phenomena Observed with {\it Hinode}/EIS in the 2006 December 13 Solar Flare
We present a detailed examination of strongly blueshifted emission lines
observed with the EUV Imaging Spectrometer on board the {\it Hinode} satellite.
We found two kinds of blueshifted phenomenon associated with the X3.4 flare
that occurred on 2006 December 13. One was related to a plasmoid ejection seen
in soft X-rays. It was very bright in all the lines used for the observations.
The other was associated with the faint arc-shaped ejection seen in soft
X-rays. The soft X-ray ejection is thought to be an MHD fast-mode shock wave.
This is therefore the first spectroscopic observation of an MHD fast-mode shock
wave associated with a flare.Comment: 18 pages, 1 table, 6 figures. ApJ, accepte
Identification of major dioxin-like compounds and androgen receptor antagonist in acid-treated tissue extracts of high trophic-level animals
We evaluated the applicability of combining in vitro bioassays with instrument analyses to identify potential endocrine disrupting pollutants in sulfuric acid-treated extracts of liver and/or blubber of high trophic-level animals. Dioxin-like and androgen receptor (AR) antagonistic activities were observed in Baikal seals, common cormorants, raccoon dogs, and finless porpoises by using a panel of rat and human cell-based chemical-activated luciferase gene expression (CALUX) reporter gene bioassays. On the other hand, no activity was detected in estrogen receptor α (ERα)-, glucocorticoid receptor (GR)-, progesterone receptor (PR)-, and peroxisome proliferator-activated receptor γ2 (PPARγ2)-CALUX assays with the sample amount applied. All individual samples (n = 66) showed dioxin-like activity, with values ranging from 21 to 5500 pg CALUX-2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent (TEQ)/g-lipid. Because dioxins are expected to be strong contributors to CALUX-TEQs, the median theoretical contribution of dioxins calculated from the result of chemical analysis to the experimental CALUX-TEQs was estimated to explain up to 130% for all the tested samples (n = 54). Baikal seal extracts (n = 31), but not other extracts, induced AR antagonistic activities that were 8-150 μg CALUX-flutamide equivalent (FluEQ)/g-lipid. p,p′-DDE was identified as an important causative compound for the activity, and its median theoretical contribution to the experimental CALUX-FluEQs was 59% for the tested Baikal seal tissues (n = 25). Our results demonstrate that combining in vitro CALUX assays with instrument analysis is useful for identifying persistent organic pollutant-like compounds in the tissue of wild animals on the basis of in vitro endocrine disruption toxicity. © 2011 American Chemical Society
Positive relationships between annual changes in salt intake and plasma B-type natriuretic peptide levels in the general population without hypertension and heart diseases
Excessive salt intake causes hypertension and heart diseases. B-type natriuretic peptide (BNP) is a surrogate marker of heart disease, and a slightly elevated BNP level is associated with a poor prognosis. Our previous cross-sectional study demonstrated that plasma BNP has a significant positive association with daily salt intake in the general population. However, the relationship between changes in salt intake and changes in plasma BNP remains unknown.
We recruited 3051 participants without hypertension or electrocardiogram abnormalities who underwent annual health check-ups for two consecutive years. Clinical parameters, including plasma BNP, were obtained, and daily salt intake was evaluated using urinary samples. Annual changes in these parameters were calculated.
The median plasma BNP level was 12.9pg/mL, and the daily salt intake was 8.73±1.89g. The annual changes in plasma BNP and daily salt intake were 4.79±36.38% and 2.01±21.80%, respectively. Participants in the highest quartile of annual changes in daily salt intake showed the largest annual changes in plasma BNP. Annual changes in plasma BNP indicated a significant positive association with daily salt intake. Moreover, multiple linear regression analyses revealed that annual changes in plasma BNP showed a significant positive association with daily salt intake after adjustments.
Our study showed a significant positive relationship between annual changes in plasma BNP and annual changes in daily salt intake. The suppression of plasma BNP is therefore induced by salt intake restriction. The monitoring of plasma BNP while reducing salt intake may therefore prevent heart diseases and lead to improved prognoses in the general population without heart diseases.journal articl
A case of hypertensive disorders of pregnancy that developed at 9 weeks of gestation
Preeclampsia and superimposed preeclampsia usually develop after 20 weeks of gestation. We report a case of a 35-year-old Japanese woman who developed hypertensive disorders of pregnancy (HDP) before 20 weeks of gestation. She presented with hypertension and proteinuria at 9 and 11 weeks of gestation, respectively, and developed nephrotic syndrome at 17 weeks of gestation. She did not have definite hypertension or urinary abnormalities before pregnancy. The patient was serologically positive for the antinuclear antibody. However, the complement levels were normal and anti-phospholipid antibody was not detected. A renal biopsy performed at 18 weeks of gestation showed diffuse endotheliosis and tip lesions of secondary focal segmental glomerulosclerosis but no hypertensive changes of the arterioles. Although electron microscopic examination showed electron-dense deposits in the subendothelial lesions, they were considered nonspecific plasma exudation by mass spectrometry. An abortion was performed at 20 weeks gestation because the patient’s congestive symptoms due to nephrotic syndrome had worsened and marked fetal growth restriction was observed. After delivery, the patient’s symptoms resolved immediately without any additional treatment; however, continuous antihypertensive medication was required. Finally, the patient was diagnosed with HDP based on the renal biopsy findings and her clinical course after delivery. Compared to previous reports, this case describes the earliest onset of HDP. Thus, HDP should be considered as a differential diagnosis in pregnant women with hypertension or proteinuria presenting with symptoms before 20 weeks of gestation.journal articl
Rescue from Stx2-Producing E. coli-Associated Encephalopathy by Intravenous Injection of Muse Cells in NOD-SCID Mice
Shiga toxin-producing Escherichia coli (STEC) causes hemorrhagic colitis, hemolytic uremic syndrome, and acute encephalopathies that may lead to sudden death or severe neurologic sequelae. Current treatments, including immunoglobulin G (IgG) immunoadsorption, plasma exchange, steroid pulse therapy, and the monoclonal antibody eculizumab, have limited effects against the severe neurologic sequelae. Multilineage-differentiating stress-enduring (Muse) cells are endogenous reparative non-tumorigenic stem cells that naturally reside in the body and are currently under clinical trials for regenerative medicine. When administered intravenously, Musecells accumulate to the damaged tissue, where they exert anti-inflammatory, anti-apoptotic, anti-fibrotic, and immunomodulatory effects, and replace damaged cells by differentiating into tissue-constituent cells. Here, severely immunocompromised non-obese diabetic/severe combined immunodeficiency (NOD-SCID) mice orally inoculated with 9 × 109 colony-forming units of STEC O111 and treated 48 h later with intravenous injection of 5 × 104 Muse cells exhibited 100% survival and no severe after-effects of infection. Suppression of granulocyte-colony-stimulating factor (G-CSF) by RNAi abolished the beneficial effects of Muse cells, leading to a 40% death and significant body weight loss, suggesting the involvement of G-CSF in the beneficial effects of Muse cells in STEC-infected mice. Thus, intravenous administration of Muse cells could be a candidate therapeutic approach for preventing fatal encephalopathy after STEC infection
Multi-Wavelength Observation of Electron Acceleration in the 2006 December 13 Flare
We present a multi-wavelength observation of a solar flare occurring on 2006
December 13 with Hinode, RHESSI, and the Nobeyama Radio Observatory, to study
the electron acceleration site and mechanism. The Solar Optical Telescope (SOT)
on board Hinode observed elongated flare ribbons, and RHESSI observed
double-footpoint hard X-ray (HXR) sources appearing in part of the ribbons. A
photospheric vector magnetogram obtained from SOT reveals that the HXR sources
are located at the region where horizontal magnetic fields change the
direction. The region is interpreted as the footpoint of magnetic separatrix.
Microwave images taken with the Nobeyama Radioheliograph show a loop structure
connecting the HXR sources. The brighter parts of the microwave intensity are
located between the top and footpoints of the loop. We consider these
observations as an evidence of the electron acceleration near the magnetic
separatrix and injection parallel to the field line.Comment: 20 pages, 7 figures, accepted by Ap
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