Free Trade vs . Fair Trade after the Uruguay Round , focused on trade in financial services : some remarks from the Japanese side

Ishiguro,Kazunori 국제거래법학회 1995 國際去來法硏究 Vol.4 No.1

Polarimetric Study of Near-Earth Asteroid (1566) Icarus

Ishiguro, Masateru,Kuroda, Daisuke,Watanabe, Makoto,Bach, Yoonsoo P.,Kim, Jooyeon,Lee, Mingyeong,Sekiguchi, Tomohiko,Naito, Hiroyuki,Ohtsuka, Katsuhito,Hanayama, Hidekazu,Hasegawa, Sunao,Usui, Fumihik American Institute of Physics 2017 The Astronomical journal Vol.154 No.5

<P>We conducted a polarimetric observation of the fast-rotating near-Earth asteroid (1566) Icarus at large phase (Sun-asteroid-observer's) angles alpha = 57 degrees-141 degrees around the 2015 summer solstice. We found that the maximum values of the linear polarization degree are P-max = 7.32 +/- 0.25% at phase angles of alpha(max) = 124 degrees +/- 8 degrees in the V-band and P-max = 7.04 +/- 0.21% at alpha(max) = 124 degrees +/- 6 degrees in the RC-band. Applying the polarimetric slope-albedo empirical law, we derived a geometric albedo of p(V) = 0.25 +/- 0.02, which is in agreement with that of Q-type taxonomic asteroids. amax is unambiguously larger than that of Mercury, the Moon, and another near-Earth S-type asteroid (4179) Toutatis but consistent with laboratory samples with hundreds of microns in size. The combination of the maximum polarization degree and the geometric albedo is in accordance with terrestrial rocks with a diameter of several hundreds of micrometers. The photometric function indicates a large macroscopic roughness. We hypothesize that the unique environment (i.e., the small perihelion distance q = 0.187 au and a short rotational period of T-rot = 2.27 hr) may be attributed to the paucity of small grains on the surface, as indicated on (3200) Phaethon.</P>

2006 Fragmentation of Comet 73P/Schwassmann-Wachamann 3B Observed with SUBARU/Suprime-Cam

Ishiguro Masateru 한국천문학회 2008 天文學會報 Vol.33 No.1

COMET 17P/HOLMES: CONTRAST IN ACTIVITY BETWEEN BEFORE AND AFTER THE 2007 OUTBURST

Ishiguro, Masateru,Kim, Yoonyoung,Kim, Junhan,Usui, Fumihiko,Vaubaillon, Jeremie J.,Ishihara, Daisuke,Hanayama, Hidekazu,Sarugaku, Yuki,Hasegawa, Sunao,Kasuga, Toshihiro,Warjurkar, Dhanraj S.,Ham, Ji- IOP Publishing 2013 The Astrophysical journal Vol.778 No.1

<P>A Jupiter-family comet, 17P/Holmes, underwent outbursts in 1892 and 2007. In particular, the 2007 outburst is known as the greatest outburst over the past century. However, little is known about the activity before the outburst because it was unpredicted. In addition, the time evolution of the nuclear physical status has not been systematically studied. Here, we study the activity of 17P/Holmes before and after the 2007 outburst through optical and mid-infrared observations. We found that the nucleus was highly depleted in its near-surface icy component before the outburst but that it became activated after the 2007 outburst. Assuming a conventional 1 mu m sized grain model, we derived a surface fractional active area of 0.58% +/- 0.14% before the outburst whereas the area was enlarged by a factor of similar to 50 after the 2007 outburst. We also found that large (>= 1 mm) particles could be dominant in the dust tail observed around aphelion. Based on the size of the particles, the dust production rate was >= 170 kg s(-1) at a heliocentric distance of r(h) = 4.1 AU, suggesting that the nucleus was still active around the aphelion passage. The nucleus color was similar to that of the dust particles and average for a Jupiter-family comet but different from that of most Kuiper Belt objects, implying that color may be inherent to icy bodies in the solar system. On the basis of these results, we concluded that more than 76 m of surface material was blown off by the 2007 outburst.</P>

DUST FROM COMET 209P/LINEAR DURING ITS 2014 RETURN: PARENT BODY OF A NEW METEOR SHOWER, THE MAY CAMELOPARDALIDS

Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Takahashi, Jun,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Makoto,Imai, Masataka,Goda, Shuhei,Akitaya, Hiroshi,Takagi, Yuhei,Morihana, Kumiko,Honda, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.2

<P>We report a new observation of the Jupiter family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance r(h) = 1.6AU and showed weak activity at r(h) <= 1.4AU. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q = -3.25 +/- 0.10. We derived a mass-loss rate of 2-10 kg s(-1) during the active phase and a total mass of approximate to 5 x 10(7) kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4ms(-1), which is comparable to the escape velocity from the nucleus (1.4ms(-1)). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage.</P>

INVARIANT RINGS AND DUAL REPRESENTATIONS OF DIHEDRAL GROUPS

Ishiguro, Kenshi Korean Mathematical Society 2010 대한수학회지 Vol.47 No.2

The Weyl group of a compact connected Lie group is a reflection group. If such Lie groups are locally isomorphic, the representations of the Weyl groups are rationally equivalent. They need not however be equivalent as integral representations. Turning to the invariant theory, the rational cohomology of a classifying space is a ring of invariants, which is a polynomial ring. In the modular case, we will ask if rings of invariants are polynomial algebras, and if each of them can be realized as the mod p cohomology of a space, particularly for dihedral groups.

MODULAR INVARIANTS UNDER THE ACTIONS OF SOME REFLECTION GROUPS RELATED TO WEYL GROUPS

Ishiguro, Kenshi,Koba, Takahiro,Miyauchi, Toshiyuki,Takigawa, Erika Korean Mathematical Society 2020 대한수학회보 Vol.57 No.1

Some modular representations of reflection groups related to Weyl groups are considered. The rational cohomology of the classifying space of a compact connected Lie group G with a maximal torus T is expressed as the ring of invariants, H*(BG; ℚ) ≅ H*(BT; ℚ)^W(G), which is a polynomial ring. If such Lie groups are locally isomorphic, the rational representations of their Weyl groups are equivalent. However, the integral representations need not be equivalent. Under the mod p reductions, we consider the structure of the rings, particularly for the Weyl group of symplectic groups Sp(n) and for the alternating groups A_n as the subgroup of W(SU(n)). We will ask if such rings of invariants are polynomial rings, and if each of them can be realized as the mod p cohomology of a space. For n = 3, 4, the rings under a conjugate of W(Sp(n)) are shown to be polynomial, and for n = 6, 8, they are non-polynomial. The structures of H*(BT^n-1; 𝔽_p)^A_n will be also discussed for n = 3, 4.

Dark red debris from three short-period comets: 2P/Encke, 22P/Kopff, and 65P/Gunn

Ishiguro, Masateru,Sarugaku, Yuki,Ueno, Munetaka,Miura, Naoya,Usui, Fumihiko,Chun, Moo-Young,Kwon, Suk Minn Elsevier 2007 Icarus Vol.189 No.1

<P><B>Abstract</B></P><P>We present observations of the extended dust structures near the orbits of three short-period comets: 2P/Encke, 22P/Kopff, and 65P/Gunn. The dust trails were originally discovered by the Infrared Astronomical Satellite (IRAS). Our observations were made using wide-field optical CCD cameras on the University of Hawaii 2.24-m telescope, the Canada–France–Hawaii 3.6-m telescope, and the Kiso 1.05-m Schmidt telescope. We compared the observed images with models and found that the extended structures seen around 2P/Encke and 22P/Kopff before perihelion passage were most likely “dust trails,” whereas images taken after perihelion passage show a high contamination by recently released particles (i.e., particles in Neck-Line structures are visible). We could not confirm the existence of a dust trail from 65P/Gunn within the field of view of the camera used. The effective sizes of the particles responsible for the scattered light were estimated at 1–100 mm (2P/Encke), 1–10 mm (22P/Kopff), and 100 μm–1 mm (65P/Gunn), respectively, which is consistent with previous studies of dust trails made with infrared space telescopes and optical telescopes. We evaluated the mass loss rates of these comets, averaged over their orbits, as reaching 48±20 kg<SUP>s−1</SUP> (2P/Encke), 17±3 kg<SUP>s−1</SUP> (22P/Kopff), and 27±9 kg<SUP>s−1</SUP> (65P/Gunn). These values are consistent with previous work. Therefore, the total amount of material ejected from these three comets is <SUP>102</SUP> kg<SUP>s−1</SUP>, which would contribute a considerable fraction of the <SUP>104</SUP> kg<SUP>s−1</SUP> lost within 1 AU that needs to be replaced if the zodiacal cloud is to be maintained in a steady state. We also found that the particles in the dust structures are significantly redder than the Sun and the zodiacal light, and might be redder than the average short-period comet nuclei. Specifically, the reflectivity gradients of 2P/Encke, 22P/Kopff, and 65P/Gunn are 13±7 (% <SUP>103</SUP> <SUP>Å−1</SUP>), 20±5 (% <SUP>103</SUP> <SUP>Å−1</SUP>), and 15±4 (% <SUP>103</SUP> <SUP>Å−1</SUP>), respectively. We examined the change in color with distance from the nucleus. No clear correlation was detected for 2P/Encke or 22P/Kopff to an accuracy of 3–11%, while the 65P/Gunn tail did show color variation, becoming redder with increasing distance from the nucleus. This dark red material, consisting of particles of sand–cobble size, has marginally escaped from the nuclei and will evolve into finer-grained interplanetary dust particles after subsequent collisions.</P>

DETECTION OF REMNANT DUST CLOUD ASSOCIATED WITH THE 2007 OUTBURST OF 17P/HOLMES

Ishiguro, Masateru,Sarugaku, Yuki,Kuroda, Daisuke,Hanayama, Hidekazu,Kim, Yoonyoung,Kwon, Yuna G.,Maehara, Hiroyuki,Takahashi, Jun,Terai, Tsuyoshi,Usui, Fumihiko,Vaubaillon, Jeremie J.,Morokuma, Tomok American Astronomical Society 2016 The Astrophysical journal Vol.817 No.1

<P>This article reports a new optical observation of 17P/Holmes one orbital period after the historical outburst event in 2007. We detected not only a common dust tail near the nucleus. but also a long narrow structure that extended along the position angle 274 degrees.6 +/- 0 degrees.1 beyond the field of view (FOV) of the Kiso Wide Field Camera, i.e., >0 degrees.2 eastward and >2 degrees.0 westward from the nuclear position. The width of the structure decreased westward with increasing distance from the nucleus. We obtained the total cross section of the long extended structure in the FOV, C-FOV = (2.3 +/- 0.5) x 10(10) m(2). From the position angle, morphology, and mass, we concluded that the long. narrow structure consists of materials ejected during the 2007 outburst. On the basis of the dynamical behavior of dust grains in the solar radiation field, we estimated that the long. narrow structure would be composed of 1 mm(-1) cm grains having an ejection velocity of >50 m s(-1). The velocity was more than one order of magnitude faster than that of millimeter-centimeter grains from typical comets around a heliocentric distance r(h) of 2.5 AU. We considered that sudden sublimation of a large amount of water-ice (approximate to 10(30) mol s(-1)) would be responsible for the high ejection velocity. We finally estimated a total mass of M-TOT = (4-8) x 10(11) kg and a total kinetic energy of E-TOT = (1-6) x 10(15) J for the 2007 outburst ejecta, which are consistent with those of previous studies that were conducted soon after the outburst.</P>

2014-2015 MULTIPLE OUTBURSTS OF 15P/FINLAY

Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Kwon, Yuna Grace,Kim, Yoonyoung,Lee, Myung Gyoon,Watanabe, Makoto,Akitaya, Hiroshi,Kawabata, Koji,Itoh, Ryosuke,Nakaoka, Tatsuya,Yoshida, Michitos American Astronomical Society 2016 The Astronomical journal Vol.152 No.6

<P>Multiple outbursts of a Jupiter-family comet (JFC), 15P/Finlay, occurred from late 2014 to early 2015. We conducted an observation of the comet after the first outburst and subsequently witnessed another outburst on 2015 January 15.6-15.7. The gas, consisting mostly of C-2 and CN, and dust particles expanded at speeds of 1110 +/- 180 m s(-1) and 570 +/- 40 m s(-1) at a heliocentric distance of 1.0 au. We estimated the maximum ratio of solar radiation pressure with respect to the solar gravity beta(max) = 1.6 +/- 0.2, which is consistent with porous dust particles composed of silicates and organics. We found that 10(8)-10(9) kg of dust particles (assumed to be 0.3 mu m - 1 mm) were ejected through each outburst. Although the total mass is three orders of magnitude smaller than that of the 17P/Holmes event observed in 2007, the kinetic energy per unit mass (10(4) J kg(-1)) is equivalent to the estimated values of 17P/Holmes and 332P/2010 V1 (Ikeya-Murakami), suggesting that the outbursts were caused by a similar physical mechanism. From a survey of cometary outbursts on the basis of voluntary reports, we conjecture that 15P/Finlay-class outbursts occur >1.5 times annually and inject dust particles from JFCs and Encke-type comets into interplanetary space at a rate of similar to 10 kg s(-1) or more.</P>