Asymptotic degeneracies of M2-brane SCFTs

We study the asymptotic growth of the degeneracy of the BPS local operators with scaling dimension $n/2$ in the three-dimensional superconformal field theories describing $N$ M2-branes. From the large $N$ supersymmetric indices we obtain the asymptotic formulas for degeneracies of the M2-brane SCFTs according to the Meinardus theorem. We observe an intriguing universal $n^{2/3}$ growth of the degeneracies in various theories of M2-brane SCFTs. We also determine the coefficients of $n^{2/3}$ growth as well as further corrections in these theories explicitly.Comment: 59 page

Cosmic-ray exposure ages of enstatite chondrites

Eleven enstatite (E-) chondrites were analyzed for abundances and isotopic ratios of noble gases by total melting. Light noble gases, He, Ne and Ar are discussed. We obtained cosmic-ray exposure ages (T^) based on cosmogenic ^Ne that are divided into two groups, below 15 Myr and above 40 Myr. Both ranges of T^ contain various petrologic-types of E-chondrites. Isotopic ratios and concentration of Ne for Yamato (Y)-8414 and -86004 are almost the same, which suggests that they are from a common fragment. Identical exposure age T^ of 10 Myr for Y-8414 and -86004 supports their pairing. The pairing for Y-8414 and -86004 based on noble-gas signatures and T^ is consistent with their petrologic similarities. Pairing for Y-792959 and -793161 is also suggested by their similarities in mineral compositions, their close sampling location and the same petrologic-type. However, there are discrepancies in He and Ar contents between the two samples, which fails to support their pairing. Including literature data, the exposure ages show no systematic correlation with petrologic type. Additionally, both EH-and EL-chondrites are found in both two peaks of T^. The exposure age distribution has no implications about the structure of E-chondrite parent body. The parent body of E-chondrites has possibly lost the original structure after many collisions in the early solar system evolution

A microtubule polymerase cooperates with the kinesin-6 motor and a microtubule cross-linker to promote bipolar spindle assembly in the absence of kinesin-5 and kinesin-14 in fission yeast

Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end–directed motor kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end–directed motor kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of kinesin-5/Cut7 and kinesin-14/Pkl1. One is kinesin-6/Klp9 that engages with spindle elongation once short bipolar spindles assemble. Klp9 also ensures the medial positioning of anaphase spindles to prevent unequal chromosome segregation. Another is the Alp7/TACC-Alp14/TOG microtubule polymerase complex. Temperature-sensitive alp7cut7pkl1 mutants are arrested with either monopolar or very short spindles. Forced targeting of Alp14 to the spindle pole body is sufficient to render alp7cut7pkl1 triply deleted cells viable and promote spindle assembly, indicating that Alp14-mediated microtubule polymerization from the nuclear face of the spindle pole body could generate outward force in place of Cut7 during early mitosis. The third pathway involves the Ase1/PRC1 microtubule cross-linker that stabilizes antiparallel microtubules. Our study, therefore, unveils multifaceted interplay among kinesin-dependent and -independent pathways leading to mitotic bipolar spindle assembly.This work was supported by the Japan Society for the Promotion of Science (JSPS) (KAKENHI Scientific Research [A] 16H02503 to T.T., a Challenging Exploratory Research grant 16K14672 to T.T., Scientific Research [C] 16K07694 to M.Y.), the Naito Foundation (T.T.), and the Uehara Memorial Foundation (T.T.)

Topkapı Sarayı Müzesinde Türk saatleri

Taha Toros Arşivi, Dosya No: 114-Müzelerİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Ultrafast Control of Crystal Structure in a Topological Charge-Density-Wave Material

Optical control of crystal structures is a promising route to change physical properties including topological nature of a targeting material. Time-resolved X-ray diffraction measurements using the X-ray free-electron laser are performed to study the ultrafast lattice dynamics of VTe$_2$, which shows a unique charge-density-wave (CDW) ordering coupled to the topological surface states as a first-order phase transition. A significant oscillation of the CDW amplitude mode is observed at a superlattice reflection as well as Bragg reflections. The frequency of the oscillation is independent of the fluence of the pumping laser, which is prominent to the CDW ordering of the first-order phase transition. Furthermore, the timescale of the photoinduced 1$T^{\prime\prime}$ to 1$T$ phase transition is independent of the period of the CDW amplitude mode

Formation of an Ultracarbonaceous Antarctic Micrometeorite through Minimum Aqueous Alteration in a Small Porous Icy Body

A comprehensive study of the organic chemistry and mineralogy of an ultracarbonaceous micrometeorite (UCAMM D05IB80) collected from near the Dome Fuji Station, Antarctica, was carried out to understand the genetic relationship among organic materials, silicates, and water. The micrometeorite is composed of a dense aggregate of ∼5 µm-sized hollow ellipsoidal organic material containing submicrometer-sized phases such as glass with embedded metal and sulfides (GEMS) and mineral grains. There is a wide area of organic material (∼15 × 15 μm) in its interior. Low-Ca pyroxene is much more abundant than olivine and shows various Mg/(Mg + Fe) ratios ranging from ∼1.0 to 0.78, which is common to previous works on UCAMMs. By contrast, GEMS grains in this UCAMM have unusual chemical compositions. They are depleted in both Mg and S, which suggests that these elements were leached out from the GEMS grains during very weak aqueous alteration, without the formation of phyllosilicates. The organic materials have two textures—smooth and globular with an irregular outline—and these are composed of imine, nitrile and/or aromatic nitrogen heterocycles, and amide. The ratio of nitrogen to carbon (N/C) in the smooth region of the organics is ∼0.15, which is five times higher than that of insoluble organic macromolecules in types 1 and 2 carbonaceous chondritic meteorites. In addition, the UCAMM organic materials are soluble in epoxy and are thus hydrophilic; this polar nature indicates that they are very primitive. The surface of the material is coated with an inorganic layer, a few nanometers thick, that consists of C, O, Si, S, and Fe. Sulfur is also contained in the interior, implying the presence of organosulfur moieties. There are no isotopic anomalies of D, 13C, or 15N in the organic material. Interstellar photochemistry alone would not be sufficient to explain the N/C ratio of the UCAMM organics; therefore, we suggest that a very small amount of fluid on a comet must have been necessary for the formation of the UCAMM. The GEMS grains depleted in Mg and S in the UCAMM prove a very weak degree of aqueous alteration; weaker than that of carbonaceous chondrites. Short-duration weak alteration probably caused by planetesimal shock locally melted cometary ice grains and released water that dissolved the organics; the fluid would likely have not mobilized because of the very low thermal conductivity of the porous icy body. This event allowed the formation of the large organic puddle of the UCAMM, as well as organic matter sulfurization, formation of thin membrane-like layers of minerals, and deformation of organic nanoglobules.アクセプト後にタイトル・アブストラクト等変更あり、著者最終稿は変更前のタイトル"Formation of an Ultracarbonaceous Antarctic Micrometeorite through Minimum Aqueous Alteration in a Small Porous Icy Body"This work was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology (No. 22224010, PI: H. Nagahara). The STXM facility at the beamline 5.3.2.2, ALS, is supported by the Department of Energy, Basic Energy Sciences Program

Organic chemical variation between hydrous and anhydrous Antarctic micrometeorites

第6回極域科学シンポジウム[OA] 南極隕石11月17日（火）　国立国語研究所 2階 講