Radio observations of filaments during the eclipses of September 11, 1969 and March 7, 1970     

M. Simon  Bengt-Arne Wickström 《Solar physics》1971,20(1):122-129

By high resolution observations at 3 mm wavelength during the eclipses of September 11, 1969 and March 7, 1970 we have observed two filaments on the solar disc in absorption. We analyze in detail the 3.3 mm eclipse data and 9.5 mm (non-eclipse) data we have pertaining to the large filament observed on September 11, 1969. At 3.3 mm the plasma temperature in the filament is about 3900K, and at 9.5 mm it is about 6400K, indicating a multicomponent model. An upper bound of N _e ² L < 10²⁸ for the emission measure of a hot component at T > 10⁴K is obtained.  相似文献   

Photo's from Proceedings of the Third MicroQuasar Workshop; Granada Worshop on Galactic Relativistic Jet Sources – Granada,Spain, 11–13 September 2000     

Herbert W. Schnopper  Eric Silver  Stephen Murray  Suzanne Romaine  Simon Bandler  Christine Jones  William Forman  Norman Madden  Jeffery Beeman  Eugene Haller  Finn Christensen  Niels Westergaard  Juan Fabregat  Victor Reglero  Alvaro Gimenez  Noah Brosch  Elia Liebowitz  Hagai Netzer  Marco Barbera  Alfonso Collura  Salvatore Sciortino 《Astrophysics and Space Science》2001,276(1):49-65

The X-Ray Spectroscopic Explorer (XRASE) has a unique combination of features that will make it possible to address many of NASA's scientific goals. These include how galaxy clusters form, the physics and chemistry of the ISM, the heating of stellar coronae, the amount and content of intergalactic baryonic matter, the mass of black holes and the formation of disks and jets in AGN and galactic binaries. XRASE has a thin foil, multilayered telescope with a large collecting area up to 10 keV, especially in the Fe K region (1100 cm²). Its microcalorimeter array combines high energy resolution (7 eV at 6 keV) and efficiency with a field-of-view of 26 arcmin² . A deep orbit allows for long, continuous observations. Monitoring instruments in the optical (WOM-X), UV (TAUVEX) and hard X-RAY (GRAM) bands will offer exceptional opportunities to make simultaneous multi-wavelength observations.  相似文献   

GPS rapid static and kinematic positioning based on GPS active network     

CHEN  WU  HU  Congwei 《地球空间信息科学学报》2003,6(1):5-11

This paper presents a data processing strategy for GPS kinematic Positioning by using a GPS active network to model the GPS errors in double difference observable.Firstly,the double difference residuals are estimated between the reference stations in the active network.Then the errors at a user station are predicted as the network corrctions to user measurements,based on the location of the user,Finally conventional kinematic positioning algorithms can be applied to determine the position of the user station.As an example,continuous 24-hour GPS data in March 2001 has been processed by this method.It clearly demonstrates that,after applying these corrections to a user within the network,both the success rate for ambiguity resolution and the positioning accuracy have been significantly improved.  相似文献   

Antioxidants in the black mussel (Mytilus galloprovincialis) as an indicator of Black Sea coastal pollution     

Gorinstein S  Moncheva S  Katrich E  Toledo F  Arancibia P  Goshev I  Trakhtenberg S 《Marine pollution bulletin》2003,46(10):1317-1325

The biologically active compounds, antioxidant activities, and free radical scavenging effects of black mussel dry matter (Mytilus galloprovincialis)--(BMDM) were investigated. The extract from BMDM with absolute methanol (BMDMAMet) showed the strongest inhibition of lipid peroxidation as a function of its concentration, and was comparable to the antioxidant activity of butylated hydroxyanisole, at the same concentration of 0.2 mg/ml. The extract with 50%methanol/water (BMDM50%Met) had the weakest antioxidant activity, whereas other extracts such as 1.2 M HCl in 50%methanol/water (BMDM50%Met/HCl) exhibited an average inhibition of lipid peroxidation. BMDMAMet extract showed marked activities in free radical scavenging determined by beta-carotene bleaching (beta-carotene), nitric oxide (NO*) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS*+ methods. The antioxidant activities of BMDMAMet extract determined beta-carotene, NO* and ABTS*+ methods showed the highest correlation coefficients (R2) such as 0.998, 0.9976 and 0.6103, respectively, with the presence of total polyphenols. BMDM50%Met had lower antioxidant ability than BMDM50%Met/HCl in different scavenging methods, indicating that the major antioxidant components in these extracts must be derived from the polyphenols. Correlation between proteins and antioxidants was very low (0.0318 and 0.0433). The mussel extracts from polluted areas have shown by all using methods higher antioxidant activity than from the clean ones. The results presented in this report indicate that the antioxidant activities of mussel extracts could possibly be an additional index of pollution characterization.  相似文献   

A granite–gabbro complex from Madagascar: constraints on melting of the lower crust     

Andy?McMillan  Nigel?B.?W.?HarrisEmail author  Marian?Holness  Lewis?Ashwal  Simon?Kelley  Roger?Rambeloson 《Contributions to Mineralogy and Petrology》2003,145(5):585-599

The Ranomandry Complex is a Neoproterozoic, nested intrusion from central Madagascar composed of a gabbroic core within a coeval peraluminous granite ring intruding pelitic metasediments. Although xenocryst entrainment and magma mixing have both contributed to marginal phases of the granite, the primary melt is characterised by steep LREE/HREE ratios and negligible, or slightly positive, Eu anomalies. Both isotopic and trace element systematics preclude an origin from either partial melting of the metapelitic country rock or from fractional crystallisation of the gabbroic magma. However, trace-element modelling suggests an origin from the dehydration melting of a plagioclase-poor, garnet-bearing metagreywacke at temperatures of 850–900 °C and at lower crustal pressures (>10 kbar). Melting of an enriched subcontinental mantle generated gabbroic magmas that caused advective heating and anatexis at the base of thickened continental crust during their ascent. Transport of the resulting granite magma was facilitated by the pre-existing plumbing system that overcame thermal and mechanical problems associated with both diapirism and self-propagating dykes as mechanisms for long-distance transport of granite magmas. The nested geometry of the intrusions is an indication of a structurally homogeneous lower crust that contains no pre-existing shear zones or fault systems.  相似文献   

Thermal history analysis by integrated modelling of apatite fission track and vitrinite reflectance data: application to an inverted basin (Buller Coalfield, New Zealand)     

Peter J. J. Kamp  Kerry S. Webster  & Simon Nathan 《Basin Research》1996,8(4):383-402

Integrated analysis and modelling of apatite fission track with vitrinite reflectance (VR) data allows the timing, magnitude and pattern of Palaeogene subsidence and Neogene inversion to be established for an uplifted and largely denuded basin: the Buller Coalfield, New Zealand. At the time of maximum subsidence in the late Oligocene, the basin consisted of an extensional half graben, bounded to the west by the Kongahu Fault Zone (KFZ), with up to 6 km of upper Eocene to Oligocene section adjacent to it; currently, only a few tens of metres of basal coal measures on basement are preserved on top of a range 800–1000 m above sea level. Integrated modelling of the VR and fission track data show that the deepest parts of the basin were inverted during two Miocene compressional phases (24–19 Ma and 13–8 Ma), and are consistent with a further phase of inversion during the Quaternary that formed the present topography. Palinspastic restoration of the three phases of inversion shows that the basin was not inverted in a simple way: most of the rock uplift/denudation adjacent to the KFZ occurred during the early Miocene phase, and at the same time burial occurred in the south-eastern part of the basin (maximum temperatures were experienced at different times at different places in the basin); during the middle to late Miocene there was broad uplift in the central and eastern parts of the coalfield. Because the timing and magnitude of uplift have been derived from the zone of inversion, they can be compared independently with the timing of unconformity development and rapid subsidence in the adjacent foredeeps, particularly the Westport Trough. For the middle to late Miocene phase of inversion, we show that during the first 1–2 million years of compression, the uplift within the coalfield also involved the margins of the Westport Trough, contributing to unconformity development; subsequently, uplift continued on the inversion structure but the margins of the Westport Trough subsided rapidly. This is explained by a model of stick slip behaviour on the boundary faults, especially for the KFZ. When compression started the fault zone has locked and uplift extends into the basin, whereas subsequently the fault zone unlocks, and the inversion structure overrides the basin margin, thereby loading it and causing subsidence.  相似文献   

Under the Microscope: Fieldwork Practice and Cuba's Biotechnology Industry: A Reflexive Affair?     

Simon Reid-Henry 《Singapore journal of tropical geography》2003,24(2):184-197

Through a re‐reading of my Ph.D. fieldwork on Cuba's biotechnology industry, I empirically pull apart the relationship between fieldwork practice and knowledge production as experienced in my research. I argue that reflexivity is an insufficiently critiqued concept and, as a result, that its widespread influence in contemporary fieldwork practice works to obscure the influence of “others”, not just on the “doing” of research but on the conceptual development of the methodology itself. I make this argument by focusing on the various strategies I employed to actualise my research methodology, the problems I met with and the subsequent pull of my research in new directions. I cover such issues as gaining access, working in multiple locales across antagonistic polities, what happens when fieldwork goes wrong and the notion of “empirical drift”. I use these issues to examine how I was actively constructing both my field and my research methodology at the same time and through others. I try to show how the fact that fieldwork can be simultaneously a lived experience, a socially constructed performance and an episteme accounts for much of its distinctive qualities as a milieu in which existing knowledge is put to the test, or added to. I argue that these same qualities allow it to be a deeply intertextual process, or a joint work between the researcher and the field. This, I suggest, warrants greater recognition.  相似文献   

Azimuth-dependent AVO in reservoirs containing non-orthogonal fracture sets   总被引：1，自引：0，他引：1  

Colin M. Sayers  Simon Dean 《Geophysical Prospecting》2001,49(1):100-106

Azimuthal anisotropy in rocks can result from the presence of one or more sets of partially aligned fractures with orientations determined by the stress history of the rock. The symmetry of a rock with horizontal bedding that contains two or more non-orthogonal sets of vertical fractures may be approximated as monoclinic with a horizontal plane of mirror symmetry. For offsets that are small compared with the depth of the reflector, the azimuthal variation in P-wave AVO gradient for such a medium varies with azimuth as     where φ is the azimuth measured with respect to the fast polarization direction for a vertically polarized shear wave. φ ₂ depends on both the normal compliance B _N and the shear compliance B _T of the fractures and may differ from zero if B _N B _T varies significantly between fracture sets. If B _N B _T is the same for all fractures,     and the principal axes of the azimuthal variation in P-wave AVO for fixed offset are determined by the polarization directions of a vertically propagating shear wave. At larger offsets, terms in     and     are required to describe the azimuthal variation in AVO accurately. φ ₄ and φ ₆ also depend on B _N B _T. For gas-filled open fractures     but a lower value of B _N B _T may result from the presence of a fluid with non-zero bulk modulus.  相似文献   

Approaches for determining phytoplankton nutrient limitation   总被引：19，自引：0，他引：19  

John Beardall  Erica Young  Simon Roberts 《Aquatic Sciences - Research Across Boundaries》2001,63(1):44-69

  相似文献   

Erodibility of cohesive streambeds in the loess area of the midwestern USA   总被引：2，自引：0，他引：2  

G. J. Hanson  A. Simon 《水文研究》2001,15(1):23-38

Excess stress parameters, critical shear stress (τ_c) and erodibility coefficient (k_d), for degrading channels in the loess areas of the midwestern USA are presented based on in situ jet‐testing measurements. Critical shear stress and k_d are used to define the erosion resistance of the streambed. The jet‐testing apparatus applies hydraulic stresses to the bed and the resulting scour due to the impinging jet is related to the excess stress parameters. Streams tested were primarily silt‐bedded in texture with low densities, which is typical of loess soils. Results indicate that there is a wide variation in the erosion resistance of streambeds, spanning six orders of magnitude for τ_c and four orders of magnitude for k_d. Erosion resistance was observed to vary within a streambed, from streambed to streambed, and from region to region. An example of the diversity of materials within a river system is the Yalobusha River Basin in Mississippi. The median value of τ_c for the two primary bed materials, Naheola and Porters Creek Clay Formations, was 1·31 and 256 Pa, respectively. Streambeds composed of the Naheola Formation are readily eroded over the entire range of shear stresses, whereas only the deepest flows generate boundary stresses great enough to erode streambeds composed of the Porters Creek Clay Formation. Therefore, assessing material resistance and location is essential in classifying and modelling streambed erosion processes of these streams.  相似文献