Giant impacts in the Saturnian System: a possible origin of diversity in the inner mid-sized satellites

It is widely accepted that Titan and the mid-sized regular satellites around Saturn were formed in the circum-Saturn disk. Thus, if these mid-sized satellites were simply accreted by collisions of similar ice-rock satellitesimals in the disk, the observed wide diversity in density (i.e., the rock fraction) of the Saturnian mid-sized satellites is enigmatic. A recent circumplanetary disk model suggests satellite growth in an actively supplied circumplanetary disk, in which Titan-sized satellites migrate inward by interaction with the gas and are eventually lost to the gas planet. Here we report numerical simulations of giant impacts between Titan-sized migrating satellites and smaller satellites in the inner region of the Saturnian disk. Our results suggest that in a giant impact with impact velocity > 1.4 times the escape velocity and impact angle of ~45 degree, a smaller satellite is destroyed, forming multiple mid-sized satellites with a very wide diversity in satellite density (the rock fraction = 0-92 wt%). Our results of the relationship between the mass and rock fraction of the satellites resulting from giant impacts reproduce the observations of the Saturnian mid-sized satellites. Giant impacts also lead to internal melting of the formed mid-sized satellites, which would initiate strong tidal dissipation and geological activity, such as those observed on Enceladus today and Tethys in the past. Our findings also imply that giant impacts might have affected the fundamental physical property of the Saturnian mid-sized satellites as well as those of the terrestrial planets in the solar system and beyond.Comment: 18 pages, 3 figures, Planetary and Space Science, in pres

Parallel Hierarchical Matrices with Adaptive Cross Approximation on Symmetric Multiprocessing Clusters

We discuss a scheme for hierarchical matrices with adaptive cross approximation on symmetric multiprocessing clusters. We propose a set of parallel algorithms that are applicable to hierarchical matrices. The proposed algorithms are implemented using the flat-MPIand hybrid MPI+OpenMP programming models. The performance of these implementations is evaluated using an electric field analysis computed on two symmetric multiprocessing cluster systems. Although the flat-MPI version gives better parallel scalability when constructing hierarchical matrices, the speed-up reaches a limit in the hierarchical matrix-vector multiplication. We succeeded in developing a hybrid MPI+OpenMP version to improve the parallel scalability. In numerical experiments, the hybrid version exhibits a better parallel speed-up for the hierarchical matrix-vector multiplication up to 256 cores

Pars plana vitrectomy combined with penetrating keratoplasty and transscleral-sutured intraocular lens implantation in complex eyes: a case series

Background The aim of this study was to evaluate the clinical outcomes of pars plana vitrectomy (PPV) combined with penetrating keratoplasty (PKP) and transscleral-sutured intraocular lens (IOL) implantation (IOL-suture) in complex eyes. Methods In this prospective, consecutive interventional case series, patients who underwent PKP combined with PPV and IOL implantation from July 2014 to March 2018 at Yokohama Minami Kyosai Hospital were enrolled. The postoperative best corrected visual acuity (BCVA) (converted to logarithm of the minimal angle of resolution [logMAR] units), intraocular pressure (IOP, mmHg), endothelial cell density (ECD, cells/mm(2)), graft survival, complications, astigmatism, and spherical equivalent (dioptres [D]) were evaluated. Results This study included 11 eyes of 11 patients (three females and eight males; mean age, 61.8 +/- 13.9 years) with an injury (n = 6) or bullous keratopathy (n = 5). The BCVA significantly improved from 1.50 +/- 0.66 logMAR preoperatively to 0.78 +/- 0.59 logMAR (p < 0.001) postoperatively. The baseline ECD significantly decreased from 2396 +/- 238 cells/mm(2)preoperatively to 1132 +/- 323 cells/mm(2)(p < 0.001) postoperatively. Despite two rejection episodes, graft survival rates were 100%. The mean follow-up period was 38.0 +/- 20.5 months. Two patients required combined glaucoma surgery, and three patients underwent subsequent glaucoma surgery. Postoperative astigmatism and spherical equivalent were 3.9 +/- 3.2 D and 0.29 +/- 2.18 D, respectively. Conclusion The combination of PKP, PPV, and IOL-suture implantation could be a safe and effective approach for eyes requiring anterior segment surgery; however, these eyes are associated with a higher incidence of glaucoma surgery

Reconstruction of Mercury's internal magnetic field beyond the octupole

The reconstruction of Mercury’s internal magnetic field enables us to take a look into the inner heart of Mercury. In view of the BepiColombo mission, Mercury’s magnetosphere is simulated using a hybrid plasma code, and the multipoles of the internal magnetic field are estimated from the virtual spacecraft data using three distinct reconstruction methods: the truncated singular value decomposition, the Tikhonov regularization and Capon’s minimum variance projection. The study shows that a precise determination of Mercury’s internal field beyond the octupole up to the dotriacontapole is possible and that Capon’s method provides the same high performance as the Tikhonov regularization, which is superior to the performance of the truncated singular value decomposition

In Vivo Level of Poly(ADP-ribose)

PolyADP-ribosylation is a post-translational modification that plays key roles in cellular physiological functions and DNA damage responses. PolyADP-ribosylation is finely and dynamically regulated by various enzymes and factors involved in the synthesis and degradation of poly(ADP-ribose) (PAR). To better understand the function of polyADP-ribosylation, it is necessary to quantify and monitor the change of the in vivo level of PAR, the product of polyADP-ribosylation, which is rapidly turning over and kept in quite low level in cells or in organs. Recent developments of potent inhibitors of polyADP-ribosylation is expected to kill BRCA1/2-mutated breast cancer cells and ovarian cancer cells (synthetic lethality). To know the efficacy of these inhibitors in vivo, it is necessary to develop highly sensitive and reproducible methods to know PAR levels within cells or organs. However there have been several difficulties in measuring the physiologically low level of PAR without artefacts. Our experiments recently clarified that the method of sample preparation is very important in addition to the sensitivity and specificity. From reviewing the literature, including ours, we would like to emphasize the importance of the procedures of sample preparation for the assay, in addition to the sensitivity by comparing the reported PAR levels in vivo

Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356

non present