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Accuracy of the modelled wind and wave fields in enclosed seas 总被引：2，自引：0，他引：2
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CEBRIA J. M.; LOPEZ-RUIZ J.; DOBLAS M.; MARTINS L. T.; MUNHA J. 《Journal of Petrology》2003,44(3):547-568
The Messejana–Plasencia dyke (MPD) is one of the largestdoleritic dykes of the so-called Central Atlantic Magmatic Province(CAMP). Emplaced at 相似文献
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Z. MARTINS C. M. O'D. ALEXANDER G. E. ORZECHOWSKA M. L. FOGEL P. EHRENFREUND 《Meteoritics & planetary science》2007,42(12):2125-2136
Abstract— –CR chondrites are among the most primitive meteorites. In this paper, we report the first measurements of amino acids in Antarctic CR meteorites. Three CRs, Elephant Moraine (EET) 92042, Graves Nunataks (GRA) 95229, and Grosvenor Mountains (GRO) 95577, were analyzed for their amino acid content using high‐performance liquid chromatography with UV fluorescence detection (HPLC‐FD) and gas chromatography–mass spectrometry (GC‐MS). Our data show that EET 92042 and GRA 95229 are the most amino acid–rich chondrites ever analyzed, with total amino acid concentrations ranging from 180 ppm to 249 ppm. The most abundant amino acids present in the EET 92042 and GRA 95229 meteorites are the α‐amino acids glycine, isovaline, α‐aminoisobutyric acid (α‐AIB), and alanine, with δ13C values ranging from +31.6‰ to +50.5‰. The carbon isotope results together with racemic enantiomeric ratios determined for most amino acids strongly indicate an extraterrestrial origin for these compounds. Compared to Elephant Moraine (EET) 92042 and GRA 95229, the more aqueously altered GRO 95577 is depleted in amino acids. In both CRs and CMs, the absolute amino acid abundances appear to be related to the degree of aqueous alteration in their parent bodies. In addition, the relative abundances of α‐AIB and β‐alanine in the Antarctic CRs also appear to depend on the degree of aqueous alteration. 相似文献
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A multi‐proxy study of Holocene environmental change recorded in alluvial deposits along the southern coast of the Pampa region,Argentina 
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Abstract– The CO3s Colony and Ornans and LL3s Chainpur and Bishunpur were analyzed for the first time for amino acids using gas chromatography–mass spectrometry (GC‐MS). Type 3 chondrites have relatively unaltered metamorphic and petrological histories. Chainpur was the most amino acid rich of the four type 3 chondrites with a total amino acid abundance of 3330 parts per billion (ppb). The other type 3 chondrites had total amino acid abundances that ranged from 660 to 1110 ppb. A d /l ratio of <0.7 for all proteic amino acids suggests at least some amino acid terrestrial contamination. However, a small fraction of indigenous extraterrestrial amino acids cannot be excluded because of the presence of the nonprotein amino acid α‐aminoisobutyric acid (α‐AIB), and unusually high relative abundances (to glycine) of β‐alanine and γ‐ABA. The comparisons between the free and total amino acid contents of the samples also indicate a low free/total amino acid ratio (ranging from about 1:4 in CO chondrites to about 1:50 in Chainpur), which indicate that amino acids are present mainly in the bound form and were made detectable after acid hydrolysis. 相似文献
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R.R. CORDEIRO A.L.F CANOVA R. VIEIRA MARTINS 《Celestial Mechanics and Dynamical Astronomy》1997,67(3):215-224
A procedure to compute the algebraic expression for eigenvectors using algebraic manipulators associated with numerical checks
is presented. This method is applied to the computation of the eigenvectors of the matrices J·D2H for the general problems with two and three degrees of freedom. Furthermore, it is used to calculate the eigenvalues‘ signature
and to analyze stability at some equilibrium points of a generalized Hénon-Heille's Hamiltonian by Krein theory.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Abstract— CM2 carbonaceous chondrites are the most primitive material present in the solar system, and some of their subtypes, the CM and CI chondrites, contain up to 2 wt% of organic carbon. The CM2 carbonaceous chondrites contain a wide variety of complex amino acids, while the CI1 meteorites Orgueil and Ivuna display a much simpler composition, with only glycine and β‐alanine present in significant abundances. CM1 carbonaceous chondrites show a higher degree of aqueous alteration than CM2 types and therefore provide an important link between the CM2 and CI1 carbonaceous chondrites. Relative amino acid concentrations have been shown to be indicative for parent body processes with respect to the formation of this class of compounds. In order to understand the relationship of the amino acid composition between these three types of meteorites, we have analyzed for the first time three Antarctic CM1 chondrites, Meteorite Hills (MET) 01070, Allan Hills (ALH) 88045, and LaPaz Icefield (LAP) 02277, using gas chromatography‐mass spectrometry (GC‐MS) and high performance liquid chromatography‐fluorescence detection (HPLC‐FD). The concentrations of the eight most abundant amino acids in these meteorites were compared to those of the CM2s Murchison, Murray, Mighei, Lewis Cliff (LEW) 90500, ALH 83100, as well as the CI1s Orgueil and Ivuna. The total amino acid concentration in CM1 carbonaceous chondrites was found to be much lower than the average of the CM2s. Relative amino acid abundances were compared in order to identify synthetic relationships between the amino acid compositions in these meteorite classes. Our data support the hypothesis that amino acids in CM‐ and CI‐type meteorites were synthesized under different physical and chemical conditions and may best be explained with differences in the abundances of precursor compounds in the source regions of their parent bodies in combination with the decomposition of amino acids during extended aqueous alteration. 相似文献
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Oliver BOTTA Zita MARTINS Christian EMMENEGGER Jason P. DWORKIN Daniel P. GLAVIN Ralph P. HARVEY Renato ZENOBI Jeffrey L. BADA Pascale EHRENFREUND 《Meteoritics & planetary science》2008,43(9):1465-1480
Abstract— –We have analyzed ice samples and meteorites from the LaPaz region of Antarctica to investigate the composition of polycyclic aromatic hydrocarbons (PAHs) and amino acids with the goal to understand whether or not there is a compositional relationship between the two reservoirs. Four LL5 ordinary chondrites (OCs) and one CK carbonaceous chondrite were collected as part of the 2003/2004 ANSMET season. Ice samples collected from directly underneath the meteorites were extracted. In addition, exhaust particles from the snowmobiles used during the expedition were collected to investigate possible contributions from this source. The meteorite samples, the particulate matter and solid‐state extracts of the ice samples and the exhaust filters were subjected to two‐step laser mass spectrometry (L2MS) to investigate the PAH composition. For amino acids analysis, the meteorites were extracted with water and acid hydrolyzed, and the extracts were analyzed with offline OPA/NAC derivatization combined with liquid chromatography with UV fluorescence detection and time of flight mass spectrometry (LC‐FD/ToF‐MS). PAHs in the particulate matter of the ice were found to be qualitatively similar to the meteorite samples, indicating that micron‐sized grains of the meteorite may be embedded in the ice samples. The concentration levels of dissolved PAHs in all the ice samples were found to be below the detection limit of the L2MS. The PAH composition of the snowmobile exhaust is significantly different to the one in particulate matter, making it an unlikely source of contamination for Antarctic meteorites. The amino acids glycine, β‐alanine and γ‐amino‐n‐butyric acid that were detected at concentrations of 3 to 19 parts per billion (ppb) are probably indigenous to the Antarctic meteorites. Some of the LaPaz ice samples were also found to contain amino acids at concentration levels of 1 to 33 parts per trillion (ppt), in particular α‐aminoisobutyric acid (AIB), an abundant non‐protein amino acid of extraterrestrial origin found in some carbonaceous chondrites. We hypothesize that this amino acid could have been extracted from Antarctic micrometeorites and the particulate matter of the meteorites during the concentration procedure of the ice samples. 相似文献
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LUCIANA MARTINS 《Geographical review》2012,102(2):225-244
In this article I reexamine Alexander Hamilton Rice's seventh expedition to Amazonia (1924–1925) in order to highlight the ways in which the image of the modern explorer was constructed through various technologies of visualization, including maps, still photography, and film. The Rice expedition was equipped with the latest surveying instruments, among them a hydroplane especially adapted for taking aerial photographs, and it was the first to attempt shortwave radio communication in the Tropics. However, the expedition's efforts to reach the headwaters of the Rio Branco ended in failure. I investigate Rice's heavy investment in making a visual record of the expedition in the context of his academic ambitions. Despite his influence in learned societies in the United States and Europe, his questionable reputation within academic circles was difficult to overcome: His reliance on publicity to enhance his academic career had adverse consequences. The retelling of Rice's tale here also sheds light on the role of indigenous local knowledge and agency in the history of exploration. All the modern surveying technology employed notwithstanding, local support remained crucial for Amazonian exploration. 相似文献
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Vertical Land Motion in the Mediterranean Sea from Altimetry and Tide Gauge Stations 总被引：1，自引：0，他引：1
We have computed estimates of the rate of vertical land motion in the Mediterranean Sea from differences of sea level heights measured by the TOPEX/Poseidon radar altimeter and by a set of tide gauge stations. The comparison of data at 16 tide gauges, using both hourly data from local datasets and monthly data from the PSMSL dataset, shows a general agreement, significant differences are found at only one location. Differences of near-simultaneous, monthly and deseasoned monthly sea level height time-series have been considered in order to reduce the error in the estimated linear-term. In a subset of 23 tide gauge stations the mean accuracy of the estimated vertical rates is 2.3 ± 0.8 mm/yr. Results for various stations are in agreement with estimates of vertical land motion from geodetic methods. A comparison with vertical motion estimated by GPS at four locations shows a mean difference of ?0.04 ± 1.8 mm/yr, however the length of the GPS time-series and the number of locations are too small to draw general conclusions. 相似文献
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