The chemistry of interstellar CH: The contribution of Bates and Spitzer (1951)     

David A. Williams 《Planetary and Space Science》1992,40(12):1683-1693

We review the present understanding of interstellar CH⁺. We show that the essential chemistry was correctly identified by Bates and Spitzer in 1951. More recent work has been concerned with defining appropriate venues within which this chemistry can function efficiently. This process had led to a much fuller understanding of the nature of the interstellar medium.  相似文献   

Cokriging Limited Transmissivity Data Using Widely Sampled Specific Capacity from Pump Tests in an Alluvial Aquifer     

Lance Hughson  David Huntley  M. Razack 《Ground water》1996,34(1):12-18

  相似文献   

Rift-related Jurassic basaltic phreatomagmatic volcanism in the central Transantarctic Mountains: precursory stage to flood-basalt effusion     

Richard E. Hanson  David H. Elliot 《Bulletin of Volcanology》1996,58(5):327-347

 The Middle Jurassic Kirkpatrick flood basalts and comagmatic Ferrar intrusions in the Transantarctic Mountains represent a major pulse of tholeiitic magmatism related to early stages in the breakup of Gondwana. A record of the volcano-tectonic events leading to formation of this continental flood-basalt province is provided by strata underlying and only slightly predating the Kirkpatrick lavas. In the central Transantarctic Mountains, the lavas rest on widespread (≥7500 km²) tholeiitic pyroclastic deposits of the Prebble Formation. The Prebble Formation is dominated by lahar deposits and is an unusual example of a regionally developed basaltic lahar field. Related, partly fault-controlled pyroclastic intrusions cut underlying strata, and vents are represented by the preserved flanks of two small tephra cones associated with a volcanic neck. Lahar and air-fall deposits typically contain 50–60% accidental lithic fragments and sand grains derived from underlying Triassic – Lower Jurassic strata in the upper part of the Beacon Supergroup. Juvenile basaltic ash and fine lapilli consist of nonvesicular to scoriaceous tachylite, sideromelane, and palagonite, and have characteristics indicating derivation from hydrovolcanic eruptions. The abundance of accidental debris from underlying Beacon strata points to explosive phreatomagmatic interaction of basaltic magma with wet sediment and groundwater, which appears to have occurred in particular where rising magma intersected upper Beacon sand aquifers. Composite clasts in the lahar deposits exhibit complex peperitic textures formed during fine-scale intermixing of basaltic magma with wet sand and record steps in subsurface fuel-coolant interactions leading to explosive eruption. The widespread, sustained phreatomagmatic activity is inferred to have occurred in a groundwater-rich topographic basin linked to an evolving Jurassic rift zone in the Transantarctic Mountains. Coeval basaltic phreatomagmatic deposits of the Mawson and Exposure Hill Formations, which underlie exposures of the Kirkpatrick Basalt up to 1500 km to the north along strike in Victoria Land, appear to represent other parts of a regional, extension-related Middle Jurassic phreatomagmatic province which developed immediately prior to rapid outpouring of the flood basalts. This is consistent with models which assign an important role to lithospheric stretching in the generation of flood-basalt provinces. Received: 28 August 1995 / Accepted: 18 April 1996  相似文献   

The 2dF QSO Redshift Survey – VI. Measuring Λ and β from redshift-space distortions in the power spectrum     

P.J. Outram  Fiona Hoyle  T. Shanks  B.J. Boyle  S.M. Croom  N.S. Loaring  L. Miller  R.J. Smith 《Monthly notices of the Royal Astronomical Society》2001,328(1):174-184

  相似文献   

The mass of the white dwarf in the recurrent nova U Scorpii     

T.D. Thoroughgood  V.S. Dhillon  S.P. Littlefair  T.R. Marsh  D.A. Smith 《Monthly notices of the Royal Astronomical Society》2001,327(4):1323-1333

We present spectroscopy of the eclipsing recurrent nova U Sco. The radial velocity semi-amplitude of the primary star was found to be     from the motion of the wings of the He  ii λ 4686-Å emission line. By detecting weak absorption features from the secondary star, we find its radial velocity semi-amplitude to be     . From these parameters, we obtain a mass of     for the white dwarf primary star and a mass of     for the secondary star. The radius of the secondary is calculated to be     , confirming that it is evolved. The inclination of the system is calculated to be     , consistent with the deep eclipse seen in the light-curves. The helium emission lines are double-peaked, with the blueshifted regions of the disc being eclipsed prior to the redshifted regions, clearly indicating the presence of an accretion disc. The high mass of the white dwarf is consistent with the thermonuclear runaway model of recurrent nova outbursts, and confirms that U Sco is the best Type Ia supernova progenitor currently known. We predict that U Sco is likely to explode within ∼700 000 yr.  相似文献   

CSCO_3 CYCLES IN SALAWUSU RIVER BASINSINCE 150KA B.P.     

LUO Kai-li    LI Bao-sheng    ZHU Yi-zhi  JIN He-ling  ZHANG David Dian  YAN Man-cun  LI Hou-xin  YAO Chun-xia  ZHANG Yu-hongf . Department of Geography  South China Normal University  Guangzhou  P. R. China  . State Key Labor 《中国地理科学(英文版)》2001,11(4):336-342

About 70years ago，Frenc卜卜alaeohdoglst回LL sc卜dars al卜ome and a卜road卜ave successively con－HARD de Chardin P．et al．Initiated the Quaternary ducted large amount ofwork on the Later Quaternarygeologlcal research In the ＞alawusu River Basin of strata（TEILHARD，1924； YUAN，1978； LI，1987；desert region of Northern China and established th，ZHENG，1989； SUN et al，1996； LI et al，1993），Salawusu Formation门EILHARD，1924）．Sine，then，palaeobiology…  相似文献   

Prediction in Real Time of the 2000 July 14 Heliospheric Shock Wave and its Companions During the `Bastille' Epoch*     

Dryer  M.  Fry  C.D.  Sun  W.  Deehr  C.  Smith  Z.  Akasofu  S.-I.  Andrews  M.D. 《Solar physics》2001,204(1-2):265-284

Prediction of solar-generated disturbances and their three-dimensional propagation through interplanetary space continues to present a vitally important operational space weather forecasting objective. This paper presents the first successful real-time prediction of a series of major heliospheric shock waves at Earth, including the one from the 14 July 2000 (`Bastille Day') flare. An ensemble of three models and their predictions were distributed to a world-wide group of interested scientists as part of an informal Internet space weather forecast research program. Two of the models, STOA (Shock Time of Arrival) and ISPM (Interplanetary Shock Propagation Model), presently in operation by the US Air Force Weather Agency, provided predictions of shock arrival time (SAT) that were, respectively, 0.5 hours after and 3.7 hours before the observed arrival. The third model, HAFv.2 (Hakamada–Akasofu–Fry version 2.0) predicted a time 0.3 hours after the observed shock arrival time (14:37 UT, 15 July 2000). Of primary interest to this study is the third model, firstly in terms of its capability of propagating shocks through non-uniform solar wind conditions, and secondly, in terms of its ability to integrate multiple solar events and display them graphically along with the background solar wind. This latter capability was brought to bear on ten real-time-reported flares, some with CMEs (coronal mass ejections) that took place as companions to the Bastille flare during the period 7–15 July 2000. Some limited statistics are given regarding the three models' shock arrival prediction capability at Earth, as an extension of our earlier studies with this three model ensemble in the prediction of SAT. HAFv.2, however, was able to describe not only the ten events and their interaction as measured at Earth, but also at the spacecraft NEAR (orbiting the asteroid, Eros, at 1.8 AU), and CASSINI (en route, at 4.0 AU, to Saturn). Several important points are noted: (1) this epoch represents a small statistical sample that should be expanded; and (2) the three models, based on theory, empiricism, and simulations represent the state of the art that should presage a similar community process. This paper was presented earlier as an Invited Talk at the American Geophysical Union Fall Meeting, December 14–19, 2000, in San Francisco, CA, U.S.A.toward space weather objectives in the Sun-Earth domain. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014200719867  相似文献   

The Gulf of Maine boundary: Dropping anchor or setting a course?     

Ted L. McDorman  Phillip M. Saunders  David L. VanderZwaag 《Marine Policy》1985,9(2):90-107

  相似文献   

Palaeomagnetism of the Tudor gabbro, Ontario: evidence for divergence between Grenvillia and interior Laurentia     

David J. Dunlop  Hironobu Hyodo  Todd Knight  Alan G. Steele 《Geophysical Journal International》1985,83(3):699-720

Summary. After thermal and alternating field (AF) cleaning, the characteristic high blocking temperature A component of natural remanent magnetization (NRM) of the Tudor gabbro of southern Ontario has a mean direction D = 326°, I =–46° ( k = 132, α₉₅= 4.8°, N = 8 sites). The corresponding palaeopole, 133°E, 12°N ( dp = 4°, dm = 6°), confirms the palaeopole 137°E, 17°N (α₉₅= 8.4°) reported earlier by Palmer & Carmichael, based on AF cleaning only. The A NRM has unblocking temperatures > 515–525°C which exceed the estimated 500°C peak temperature reached locally during ∼ 1050 Ma Grenvillian regional metamorphism. The A NRM therefore predates metamorphism and is probably a primary thermoremanence (TRM). The age of the Tudor NRM has previously been taken to be about 675 Ma, but recent ⁴⁰Ar/³⁹Ar dating by Baksi has shown that this is the time of post-metamorphic cooling to 200–250°C. Hornblendes record initial cooling of the intrusion to 590±20°C at 1110 Ma and this is the best estimate of the age of the A remanence. Successful Thellier-type palaeointensity determinations on 11 Tudor samples confirm that the A NRM is a TRM and indicate a palaeofield at this time of 18–27 μT, about 50–70 per cent of the present field intensity at 27° magnetic latitude. The anomalous Tudor A palaeopole, which lies well to the west of both 1000–800 Ma Grenvillian palaeopoles and 1100–1050 Ma poles from Interior Laurentia, is interpreted as recording divergence between Grenvillia and Interior Laurentia just before the Grenvillian orogeny, rather than a post-metamorphic extension of the apparent polar wander path as previously assumed.  相似文献   

The Kaidun meteorite: Mineralogy of an unusual CM1 lithology     

Michael E. ZOLENSKY  Andrei V. IVANOV  S. Vincent YANG  David W. MITTLEFEHLDT  Kazumasa OHSUMI 《Meteoritics & planetary science》1996,31(4):484-493

Abstract Kaidun is a breccia of disparate enstatite and carbonaceous chondrite clasts that continues to provide real surprises. Many Kaidun clasts have been intensely altered by aqueous fluids, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and by the presence of carbonate- and phyllo-silicate-filled veins. In this report, we describe an unusual CM lithology containing many mineralogical features not previously reported from any meteorite, including pyrrhotite, with exclusive needlelike morphologies and thick mantles of phyllosilicate, and complex aggregates of phyllosilicate, melanite garnet, crosscut by pentlandite veins. The latter features appear to be due in large part to extensive hydrothermal alteration at temperatures on the order of 450 °C, which is significantly higher than that attained during secondary processing from other known CM material.  相似文献