161 research outputs found
Non-potential field formation in the X-shaped quadrupole magnetic field configuration
Some types of solar flares are observed in X-shaped quadrupolar field
configuration. To understand the magnetic energy storage in such a region, we
studied non-potential field formation in an X-shaped quadrupolar field region
formed in the active region NOAA 11967, which produced three X-shaped M-class
flares on February 2, 2014. Nonlinear force-free field modeling was applied to
a time series of vector magnetic field maps from the Solar Optical Telescope on
board Hinode and Helioseismic and Magnetic Imager on board Solar Dynamics
Observatory. Our analysis of the temporal three-dimensional magnetic field
evolution shows that the sufficient free energy had already been stored more
than 10 hours before the occurrence of the first M-class flare and that the
storage was observed in a localized region. In this localized region,
quasi-separatrix layers (QSLs) started to develop gradually from 9 hours before
the first M-class flare. One of the flare ribbons that appeared in the first
M-class flare was co-spatial with the location of the QSLs, suggesting that the
formation of the QSLs is important in the process of energy release. These QSLs
do not appear in the potential field calculation, indicating that they were
created by the non-potential field. The formation of the QSLs was associated
with the transverse photospheric motion of the pre-emerged flux and the
emergence of a new flux. This observation indicates that the occurrence of the
flares requires the formation of QSLs in the non-potential field in which free
magnetic energy is stored in advance.Comment: Accepted for publication in Ap
Evidence on percutaneous radiofrequency and microwave ablation for liver metastases over the last decade
Purpose This review aimed to summarize the treatment outcomes of percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) for metastatic liver tumors based on the findings of published studies over the last decade.
Materials and methods Literature describing the survival outcomes of ablation therapy for liver metastases was explored using the PubMed database on April 26, 2022, and articles published in 2012 or later were selected. The included studies met the following criteria: (i) English literature, (ii) original clinical studies, and (iii) literature describing overall survival (OS) of thermal ablation for metastatic liver tumors. All case reports and cohort studies with fewer than 20 patients and those that evaluated ablation for palliative purposes were excluded.
Results RFA was the most commonly used method for ablation, while MWA was used in several recent studies. RFA and MWA for liver metastases from various primary tumors have been reported; however, majority of the studies focused on colorectal cancer. The local control rate by RFA and MWA varied widely among the studies, ranging approximately 50–90%. Five-year survival rates of 20–60% have been reported following ablation for colorectal liver metastases by a number of studies, and several reports of 10-year survival rates were also noted.
Conclusion Comparative studies of local therapies for colorectal liver metastases demonstrated that RFA provides comparable survival outcomes to surgical metastasectomy and stereotactic body radiation therapy
Isolated gestational proteinuria preceding the diagnosis of preeclampsia : an observational study
Introduction. Some pregnant women develop significant proteinuria in the absence of hypertension. However, clinical significance of isolated gestational proteinuria (IGP) is not well understood. This study aimed to determine the prevalence of IGP in singleton pregnancies and the proportion of women with IGP who subsequently developed preeclampsia (IGP-PE) among all PE cases. Material and methods. This was an observational study of 6819 women with singleton pregnancies at 12 centers, including 938 women with at least once determination of protein-to-creatinine ratio (P/Cr). Significant proteinuria in pregnancy (SPIP) was defined as P/Cr (mg/mg) level >0.27. IGP was defined as SPIP in the absence of hypertension. Gestational hypertension (GH) preceding preeclampsia (GH-PE) was defined as preeclampsia (PE) in which GH preceded SPIP. Simultaneous PE (S-PE) was defined as PE in which both SPIP and hypertension occurred simultaneously. Results. IGP and PE were diagnosed in 130 (1.9%) and 158 (2.3%) of 6819 women, respectively. Of 130 women with IGP, 32 (25%) progressed to PE and accounted for 20% of all women with PE. Hence, women with IGP had a relative risk of 13.1 (95% CI; 9.2-18.5) for developing PE compared with those without IGP [25% (32/130) vs. 1.9% (126/6689)]. At diagnosis of SPIP, P/Cr levels already exceeded 1.0 more often in women with S-PE than in those with IGP-PE [67% (33/49) vs. 44% (14/32), respectively, p = 0.031]. Conclusions. IGP is a risk factor for PE, and IGP-PE accounts for a considerable proportion (20%) of all PE
Regression of LV hypertrophy by tafamidis
Transthyretin amyloidosis (ATTR) variant is a life-threatening hereditary disease predominantly affecting the peripheral nervous system and heart. Tafamidis, which prevents the deposition of amyloid by stabilizing transthyretin, is available for the treatment of neuropathy and cardiomyopathy of ATTR. However, whether tafamidis could eliminate established amyloid deposits and improve cardiac function remains unknown. We reported a case of regression of left ventricular hypertrophy after tafamidis therapy in a patient with an ATTR variant
How many times can patients tolerate reoperation?
The frequency of resection for the recurrence of colorectal cancer has not been investigated in previous studies. Likewise, the related postoperative complications and the limit for indicating surgical resection has not been reported. Herein, we reported the complications of a highly frequent surgical approach for rectal cancer recurrence, i.e., exceeding three reoperations, based on our clinical experience. We included 15 cases exceeding two operations for the local recurrence of colorectal cancer from 2014 to 2019. We examined the postoperative complications classified as Clavien–Dindo IIIb. The positive rates of the complications were 0 (0.0%), 0 (0.0%), 2 (13.3%), 3 (37.5%), and 0 (0.0%) for the primary, 1st recurrent, 2nd recurrent, 3rd recurrent, and 4th recurrent operation group (p = 0.027), respectively. It is important to exercise caution in handling cases exceeding two reoperations (exceeding three reoperations including the primary operation)
Multicolor and multi-spot observations of Starlink's Visorsat
This study provides the results of simultaneous multicolor observations for
the first Visorsat (STARLINK-1436) and the ordinary Starlink satellite,
STARLINK-1113 in the , , , , , , , ,
, , , and bands to quantitatively investigate the extent to
which Visorsat reduces its reflected light. Our results are as follows: (1) in
most cases, Virorsat is fainter than STARLINK-1113, and the sunshade on
Visorsat, therefore, contributes to the reduction of the reflected sunlight;
(2) the magnitude at 550 km altitude (normalized magnitude) of both satellites
often reaches the naked-eye limiting magnitude ( 6.0); (3) from a blackbody
radiation model of the reflected flux, the peak of the reflected components of
both satellites is around the band; and (4) the albedo of the near infrared
range is larger than that of the optical range. Under the assumption that
Visorsat and STARLINK-1113 have the same reflectivity, we estimate the covering
factor, , of the sunshade on Visorsat, using the blackbody radiation
model: the covering factor ranges from . From
the multivariable analysis of the solar phase angle (Sun-target-observer), the
normalized magnitude, and the covering factor, the phase angle versus covering
factor distribution presents a moderate anti-correlation between them,
suggesting that the magnitudes of Visorsat depend not only on the phase angle
but also on the orientation of the sunshade along our line of sight. However,
the impact on astronomical observations from Visorsat-designed satellites
remains serious. Thus, new countermeasures are necessary for the Starlink
satellites to further reduce reflected sunlight.Comment: 31 pages, 9 figures, published in PAS
Cross-National Differences in Victimization : Disentangling the Impact of Composition and Context
Varying rates of criminal victimization across countries are assumed to be the outcome of countrylevel structural constraints that determine the supply ofmotivated o¡enders, as well as the differential composition within countries of suitable targets and capable guardianship. However, previous empirical tests of these ‘compositional’ and ‘contextual’ explanations of cross-national di¡erences
have been performed upon macro-level crime data due to the unavailability of comparable individual-level data across countries. This limitation has had two important consequences for cross-national crime research. First, micro-/meso-level mechanisms underlying cross-national differences cannot be truly inferred from macro-level data. Secondly, the e¡ects of contextual measures (e.g. income inequality) on crime are uncontrolled for compositional heterogeneity. In this
paper, these limitations are overcome by analysing individual-level victimization data across 18 countries from the International CrimeVictims Survey. Results from multi-level analyses on theft and violent victimization indicate that the national level of income inequality is positively related to risk, independent of compositional (i.e. micro- and meso-level) di¡erences. Furthermore, crossnational variation in victimization rates is not only shaped by di¡erences in national context, but
also by varying composition. More speci¢cally, countries had higher crime rates the more they consisted of urban residents and regions with lowaverage social cohesion.
Polarimetric calibration of a spectropolarimeter instrument with high precision: Sunrise chromospheric infrared spectropolarimeter (SCIP) for the sunrise iii balloon telescope
The Sunrise chromospheric infrared spectropolarimeter (SCIP) installed in the international balloon experiment sunrise iii will perform spectropolarimetric observations in the near-infrared band to measure solar photospheric and chromospheric magnetic fields simultaneously. The main components of SCIP for polarization measurements are a rotating wave plate, polarization beam splitters, and CMOS imaging sensors. In each of the sensors, SCIP records the orthogonal linearly polarized components of light. The polarization is later demodulated on-board. Each sensor covers one of the two distinct wavelength regions centered at 770 and 850 nm. To retrieve the proper circular polarization, the new parameter , defined as the 45° phase shifted component of Stokes in the modulation curve, is introduced. SCIP is aimed at achieving high polarization precision (1<3×10−4 of continuum intensity) to capture weak polarization signals in the chromosphere. The objectives of the polarization calibration test presented in this paper are to determine a response matrix of SCIP and to measure its repeatability and temperature dependence to achieve the required polarization precision. Tolerances of the response matrix elements were set after considering typical photospheric and chromospheric polarization signal levels. We constructed a feed optical system such that a telecentric beam can enter SCIP with the same -number as the light distribution instrument of the sunrise iii telescope. A wire-grid linear polarizer and achromatic wave plate were placed before SCIP to produce the known polarization. The obtained response matrix was close to the values expected from the design. The wavelength and spatial variations, repeatability, and temperature dependence of the response matrix were confirmed to be smaller than tolerances. © 2022 Optica Publishing Group.Japan Society for the Promotion of Science KAKENHI (JP18H05234); Max Planck Foundation; National Aeronautics and Space Administration (#80NSSC18K0934); ISAS/JAXA Small Mission-of Opportunity Program; Spanish Research Agency (RTI2018-096886-B-C5); Centro de Excelencia Severo Ochoa Program (SEV-2017-0709).Peer reviewe
- …