113 research outputs found
Enhancement of Terrestrial Diffuse X-ray Emission Associated With Coronal Mass Ejection and Geomagnetic Storm
We present an analysis of a Suzaku observation taken during the geomagnetic
storm of 2005 August 23-24. We found time variation of diffuse soft X-ray
emission when a coronal mass ejection hit Earth and caused a geomagnetic storm.
The diffuse emission consists of fluorescent scattering of solar X-rays and
exospheric solarwind charge exchange. The former is characterized by a neutral
oxygen emission line due to strong heating of the upper atmosphere during the
storm time, while the latter is dominated by a sum of C V, C VI, N VI, N VII, O
VII, and O VIII emission lines due to the enhanced solar wind flux in the
vicinity of the exosphere. Using the solar wind data taken with the ACE and
WIND satellites,a time correlation between the solar wind and the strong O VII
line flux were investigated. We estimated necessary column densities for the
solar X-ray scattering and exospheric SWCX. From these results, we argue that a
part of the solar wind ions enter inside the magnetosphere and cause the SWCX
reaction.Comment: 33 pages, 16 figures, accepted for publication in PAS
Modeling of geocoronal solar wind charge exchange events detected with Suzaku
A model of geocoronal solar wind charge exchange (SWCX) emission was built
and compared to five Suzaku detections of bright geocoronal SWCX events. An
exospheric neutral hydrogen distribution model, charge exchange cross sections,
solar wind ion data taken with the ACE and WIND satellites, and magnetic field
models of the Earth's magnetosphere are all combined in order to predict
time-variable geocoronal SWCX emission depending on line-of-sight directions of
the Suzaku satellite. The modeled average intensities of O VII emission lines
were consistent with the observed ones within a factor of three in four out of
the five cases except for an event in which a line-of-sight direction was
toward the night side of the high-latitude magnetosheath and a major
geomagnetic storm was observed. Those of O VIII emission lines were
underestimated by a factor of three or more in all the five cases. On the other
hand, the modeled O VII and O VIII light curves reproduced the observed ones
after being scaled by ratios between the observed and modeled average
intensities. In particular, short-term variations due to line-of-sight
directions traversing cusp regions during an orbital motion of the Suzaku
satellite were reproduced. These results are discussed in the context of model
uncertainties.Comment: 47 pages, 23 figures, accepted for publication in PAS
Pathological Complete Response Patients after Neoadjuvant Chemotherapy in Breast Cancer
Cases of breast cancer metastasis after achieving a pathological complete response (pCR) with neoadjuvant chemotherapy (NAC) are sometimes encountered in clinical practice. We investigated the prognostic factors for pCR in patients with breast cancer after NAC. This retrospective cohort study included patients with localized breast cancer who underwent NAC followed by surgery between 2004 and 2020 and achieved a pCR. The associations between clinical factors and distant metastasis-free survival rate were statistically analyzed. We analyzed data for 127 patients. Twelve patients (9.4%) had distant metastases, and seven (5.5%) died. For estrogen receptor (ER)-positive patients, the distant metastasis-free survival rate was 94.6% for both 5 and 8 years. In contrast, ER-negative patients had a distant metastasis-free survival rate of 87.6% and 85.4% for 5 and 8 years (p=0.094), respectively. In cT0-2 patients, the distant metastasis-free survival rate was 92.4% for 5 years and 90.5% for 8 years, whereas in cT3-4 patients, the distant metastasis-free survival rate was 83.5% for 5 years and 83.5% for 8 years (p=0.301). This study suggested that patients with ER-negative, pre-NAC cT3 or T4 breast cancer who had achieved a pCR after NAC tended to have a worse prognosis
Development and evaluation of a master-slave robot system for single-incision laparoscopic surgery
Single-incision laparoscopic surgery (SILS) brings cosmetic benefits for patients, but this procedure is more difficult than laparoscopic surgery. In order to reduce surgeons' burden, we have developed a master-slave robot system which can provide robot-assisted SILS as if it were performing conventional laparoscopic surgery and confirmed the feasibility of our proposed system. The proposed system is composed of an input device (master side), a surgical robot system (slave side), and a control PC. To perform SILS in the same style as regular laparoscopic surgery, input instruments are inserted into multiple incisions, and the tip position and pose of the left-sided (right-sided) robotic instrument on the slave side follow those of the right-sided (left-sided) input instruments on the master side by means of a control command from the PC. To validate the proposed system, we defined four operating conditions and conducted simulation experiments and physical experiments with surgeons under these conditions, then compared the results. In the simulation experiments, we found learning effects between trials (P = 0.00013 0.1), and the task time of our system was significantly shorter than the simulated SILS (P = 0.011 < 0.05). In the physical experiments, our system performed SILS more easily, efficiently, and intuitively than the other operating conditions. Our proposed system enabled the surgeons to perform SILS as if they were operating conventionally with laparoscopic techniques.ArticleINTERNATIONAL JOURNAL OF COMPUTER ASSISTED RADIOLOGY AND SURGERY. 7(2):289-296 (2012)journal articl
Suzaku observation of Jupiter's X-rays around solar maximum
We report on results of imaging and spectral studies of X-ray emission from
Jupiter observed by Suzaku. In 2006 Suzaku had found diffuse X-ray emission in
1\unicode{x2013}5 keV associated with Jovian inner radiation belts. It has
been suggested that the emission is caused by the inverse-Compton scattering by
ultra-relativistic electrons ( MeV) in Jupiter's magnetosphere. To
confirm the existence of this emission and to understand its relation to the
solar activity, we conducted an additional Suzaku observation in 2014 around
the maximum of the 24th solar cycle. As a result, we successfully found again
the diffuse emission around Jupiter in 1\unicode{x2013}5 keV and also
point-like emission in 0.4\unicode{x2013}1 keV. The luminosity of the
point-like emission which was probably composed of solar X-ray scattering,
charge exchange, or auroral bremsstrahlung emission increased by a factor of with respect to 2006, most likely due to an increase of the solar
activity. The diffuse emission spectrum in the 1\unicode{x2013}5 keV band was
well-fitted with a flat power-law function () as in the
past observation, which supported the inverse-Compton scattering hypothesis.
However, its spatial distribution changed from Jovian
radius (Rj) to Rj. The luminosity of the diffuse emission
increased by a smaller factor of . This indicates that the diffuse
emission is not simply responding to the solar activity, which is also known to
cause little effect on the distribution of high-energy electrons around
Jupiter. Further sensitive study of the spatial and spectral distributions of
the diffuse hard X-ray emission is important to understand how high-energy
particles are accelerated in Jupiter's magnetosphere.Comment: 17 pages, 4 figures, 1 tabl
Inhibitory effects of RAGE-aptamer on development of monocrotaline-induced pulmonary arterial hypertension in rats
Background: The receptor for advanced glycation end products (RAGE), a transmembrane receptor belonging to the immunoglobulin superfamily, is overexpressed in pulmonary artery smooth muscle cells (PASMCs) in patients with pulmonary arterial hypertension (PAH) and is implicated in the etiology of PAH. Recently, we reported that RAGE-aptamer, a short and single-stranded DNA directed against RAGE, inhibited an inappropriate increase in cultured PASMCs in PAH. The aim of this study was to determine the efficacy of RAGEaptamer in monocrotaline-induced PAH in rats.
Methods and Results: Rats were assigned to either an untreated control group, a group that received continuous subcutaneous administration of RAGE-aptamer immediately after monocrotaline injection, or a group that received control-aptamer immediately after monocrotaline injection. All rats survived 21 days after injection of monocrotaline and control-aptamer or RAGE-aptamer. Injection of monocrotaline with continuous subcutaneous delivery of control-aptamer resulted in higher right ventricular systolic pressure compared with controls. This increase was attenuated by continuous subcutaneous delivery of RAGE-aptamer. The proportion of small pulmonary arteries with full muscularization was greater in the monocrotaline and control-aptamer group than in the control group. Continuous subcutaneous delivery of RAGE-aptamer significantly reduced the percentage of small pulmonary arteries with full muscularization Conclusions: Continuous subcutaneous delivery of RAGE-aptamer suppresses development of monocrotaline-induced PAH in rats. Inhibition of RAGE ameliorates muscularization of 3 small pulmonary arteries. Treatment with RAGE-aptamer might be a new therapeutic option for PAH
- …