Showing papers in "Progress in Natural Science in 2003"

Sinian-Cambrian stratigraphic framework for shallow- to deep-water environments of the Yangtze Platform: an integrated approach

Abstract: The Sinian (Terminal Proterozoic) and Early Cambrian shallow- to deep-water sequences of the Yangtze Platform were investigated. Based on integrated lithostratigraphic, biostratigraphic, and other approaches, the shallow-water sequence from the base of the Sinian (base of the Doushantuo Formation) to the top of the Qiongzhusian (top of the Yu'anshan Formation) was subdivided into 12 stratigraphic intervals. These 12 intervals were applied in turn to the subdivision and correlation of the sequences present in various facies of the Yangtze Platform. The high-resolution stratigraphic framework here developed can serve as a time frame for ongoing multidisciplinary analyses of the “Cambrian explosion”.

Asymptotic behavior of the shock solution for a class of nonlinear equations

Abstract: The high precision approximation of the shock solution for a class of nonlinear problems is obtained using a simple method.

Re-Os isotopes and PGE geochemistry of black shales and intercalated Ni-Mo polymetallic sulfide bed from the Lower Cambrian Niutitang Formation, South China

Abstract: The Lower Cambrian Niutitang Formation consists of a thick black shale sequence with a regionally distributed conformable Ni Mo polymetallic sulfide horizon and a chert bed at its basal strata on theYangtze Platform, South China. In this paper, we discuss all available data on Re Os isotopes and Platinum Group Element (PGE) distribution pattern of the Ni Mo polymetallic sulfide ore and its host rocks (black shales, cherts, and phosphorites) from Guizhou and Hunan provinces. Our results show that the black shales and the Ni Mo sulfide ore have a high initial 187 Os/ 188 Os ratio of 0.78～0.86, indicating that the Early Cambrian ocean across the Yangtze Platform had a highly radiogenic Os value. This ratio is slightly lower than but still similar to present day seawater, possibly as a result of high continental weathering at that time. The Ni Mo sulfide ore yields a Re Os isochron of 537±10 Ma (MSWD=11.9), possibly representing the depositional age of the Niutitang Formation. The chondrite normalized PGE pattern, Pt anomaly (Pt/Pt *), Pt/Pd, Ir/Pd, Au/Ir and Re/Mo ratios of the Ni Mo sulfide ore and its host rocks from South China indicate a varying source contribution of the PGE and other metals for different rocks. It is suggested that the cherts and Ni Mo sulfide ore may have a significant proportion of PGE and probably other metals deriving from submarine hydrothermal fluids with a mantle signature.

A model for assessing effects of climate change on runoff in China

Abstract: A model is established for assessing the effects of climate change on runoff in China based on the land surface parameterization scheme variable infiltration capacity (VIC). The entire area of China is represented by 2604 cells with a resolution of 60 km × 60 km for each cell. Forcing data, soil and vegetation parameters needed by the VIC model for the entire area of China are prepared. Daily forcing data, which are obtained from 740 stations between 1980 and 1990, are interpolated to the 60 km × 60 km grid system. The VIC model is run on every grid cell over the whole China, and a routing scheme is run offline with daily input of surface runoff and drainage from the VIC to get hydrograph at basin outlets. The spatial patterns of simulated runoff and mean annual precipitation are consistent very well. The results of monthly streamflow simulations over the Huaihe and Weihe River basins indicate that there is a good agreement between the observed and simulated values, and also initially indicate the rationality and feasibility of the evaluation model.

Hybrid ant colony algorithm for traveling salesman problem

Abstract: A hybrid approach based on ant colony algorithm for the traveling salesman problem is proposed, which is an improved algorithm characterized by adding a local search mechanism, a cross-removing strategy and candidate lists. Experimental results show that it is competitive in terms of solution quality and computation time.

Can transgenic rice cause ecological risks through transgene escape

Abstract: Alien transgene escape from genetically engineered rice to non-transgenic varieties or close wild relatives (including weedy rice) may lead to unpredictable ecological risks However, for transgene escape to occur three conditions need to be met: (i) spatially, transgenic rice and its non-transgenic counterparts or wild relatives should have sympatric distributions; (ii) temporally, the flowering time of transgenic rice and the non-transgenic varieties or wild relatives should overlap; and (iii) biologically, transgenic rice and its wild relative species should have such a sufficiently close relationship that their interspecific hybrids can have normal generative reproduction This paper presents research data on the geographic distribution, flowering habits, interspecific hybridization, and gene flow of cultivated rice (Oryza sativa) and its closely related wild relatives containing the AA genome The objective is to estimate the possibility of transgene escape to non-transgenic rice varieties

Identification of Chinese populations of Bemisia tabaci (Gennadius) by analyzing ribosomal ITS1 sequence

Abstract: Spreading of Bemisia tabaci B biotype has had a large impact on the production of vegetables, ornamental and fiber crops in many countries of the world since the 1990s. This study analyzes the ribosomal ITS1 sequence (∼520 bp) to distinguish genetic difference of B. tabaci from representative different geographical populations in China. Phylogenetic analysis shows that populations of B. tabaci from Beijing and Shandong Province are of biotype B, and populations of B. tabaci from sweet potato in Fujian Province and pumpkin in Guangxi, China, belong to two different non-B biotypes and have a geographical origin of Asia.

Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications

Abstract: Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Platform indicates that species of Tsunyidiscus and Hupeidiscus can be used for biostratigraphic correlation. T. aclis occurs only in the lower Qiongzhusian, T. armatus occurs in the lower and middle Qiongzhusian, while T. niutitangensis and T. tingi occur mainly in the middle and upper Qiongzhusian, with only T. tingi extending upward into the lower Canglangpuian. H. orientalis first appears in the upper Qiongzhusian, reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone. Biostratigraphic and lithostratigraphic correlations indicate that the limestone in the lower part of the Mingxinsi Formation, the Upper Member of Jiumenchong Formation, and the upper part of the Middle Member of the Huangbailing Formation, can be correlated with each other as Hupediscus, an index fossil of the lower Canglangpuian, is abundant in all these units. The lower part of the Niutitang and Jiumenchong formations in eastern Guizhou, which mainly represent Qiongzhusian strata, can be correlated with the Lower Member of the Huangbailing Formation. The basal part of the Niutitang Formation, which may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan, is very condensed. Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Hetang formations are not older than Qiongzhusian in age.

Solving traveling salesman problems by genetic algorithms

Abstract: The gene section ordering on solving traveling salesman problems is analyzed by numerical experiments. Some improved crossover operations are presented. Several combinations of genetic operations are examined and the functions of these operations are analyzed. The essentiality of the ordering of the gene section and the significance of the evolutionary inversion operation are discussed. Some results and conclusions are obtained and given, which provide useful information for the implementation of the genetic operations for solving the traveling salesman problem.

Stratigraphic architecture of the Neoproterozoic glacial rocks in the “Xiang-Qian-Gui” region of the central Yangtze Block, South China

Abstract: The Yangtze Block in South China is one of the important regions where Neoproterozoic glacial rocks are well developed and studied However, the classification and correlation of the Neoproterozoic glacial sequences in the central Yangtze Block stillremain controversial among Chinese geologists The original Sinian sections around the Yangtze Gorges Region became an official standard for classification and correlation since the 1950s Subsequent regional geologic studies, however, resulted in different classification and correlation, because of its incompleteness We select one of the complete sections in the bordering areas of Xiang (Hunan) Qian (Guizhou) and Gui (Guangxi) as a standard of classification and correlation The temporal and spatial distribution, ie the stratigraphic architecture, of the glacial rocks in the central Yangtze Block is suggested Our results indicate that the glacial sequence on the Yangtze Block was deposited during the Nantuo Ice-age, the Datangpo Interglacial-ag

Sulfur and carbon isotopic variations in Neoproterozoic sedimentary rocks from southern China

Abstract: A new set of δ34Ssulfide δ34Ssulfate and δ13Ccarbonate values has been reported from Neoproterozoic sedimentary rocks in southern China. The interglacial blackshales of the Datangpo Fm. display higher δ34Ssulfied values with > + 20‰. average, but the postglacial black shales from the Doushantuo Fm. show negative δ34Ccarbonate values. However, the Jinjiadong Fm., the same post-glaciation 3 as the Doushantuo Fm., has positive δ34Ssulfide values, implying that the δ34S value of sedimentary sulfides wouldbe controlled by lithofacies and paleogeographic environments. The δ34Ssulfate values relative to δ13Ccarbonate were obtained by extraction of trace sulfate from the successive carbonate sequences in the Yangtze Gorges sections. A preliminary interpretation suggests that the oceanic environment may fluctuate dramatically at the post-glacial Doushantuo stage and, then, recover its stability at the Dengying stage on the basis of the high resolution δ34S and δ13C corves of seawater.

Pyrite framboids associated with the Mesozoic Jehol Biota in northeastern China: Implications for microenvironment during early fossilization

Abstract: Despite of the recent influx of reports describing important fossil specimens from the Mesozoic Jehol Biota, detailed information on the mechanism of fossilization and paleoenvironment in which these fossils were deposited is scanty. We present an analysis of microenvironment based upon scanning electron microscope observations of in situ pyrite framboids and microcrystallines of plant and vertebrate feather fossils in the Jehol Biota. Pyrite microcrystallines and framboids occur extensively inside and on surface of plant fossils. Framboids found on feathers and in sedimentary matrix were in a lower abundance. These framboids have diameters ranging from 6 mum to 31 mum with an average of 20 mum, indicating a dysoxic aqueous condition with free oxygen level less than 30 mumol/L for the microenvironment where these framboids were formed. The outgrowth of framboids inside plant tissues suggests the presence of water molecules and free oxygen at the cellular level during pyritization; the relative timing between tissue decay and framboid formation implies a rapid tissue degradation occurred during the very early stage of fossilization. This line of reasoning is consistent with the observation that cell level structure of plant fossils from these deposits is rarely preserved. We propose a "fossil envelop" model to accommodate the different geo-chemical conditions between the microenvironment surrounding the fossil material and the macroenvironment of background lake bottom water.

Lower Cambrian small shelly faunas from Zhejiang (China) and their biostratigraphical implications

Abstract: Despite a long history of research on the Early Cambrian in China most available data on small skeletal fossils concern fossil associations of the shallow carbonate platform. Information on skeletal fossils from marginal shelf environments of the Yangtze Platform is scanty, which may reflect the rarity of fossils in deeper sedimentary environments but is also due to limitation of carbonate distribution and outcrops, difficulties in fossil extraction, and a general research focus on the Precambrian—Cambrian boundary beds on the carbonate platform. Here we present a documentation of Meishucunian to Qiongzhusian smallskeletal fossils from the lower Hetang Formation and the chert unit at its base from the Jiangshan region, Zhejiang Province, representing a relatively deep shelf environment compared to the inner shelfregion. The earliest association (Meishucunian) from the chert unit underlying the Hetang Formation is mainly characterized by the occurrence of Protohertzina anabarica, P. unguliformis, ...

Effects of Cu2+ and pH on osteoclastic bone resorption in vitro

Abstract: The effects of Cu2+ and pH on osteoclastic bone resorption lacunae are studied by culturing Japanese white rabbit osteoclasts on bone slices. The number and surface area of bone resorption lacunae are measured by photomicrography and image analysis. Concentration of calcium ion in the supernatant is measured by atomic absorption spectrometry to evaluate the activity of osteoclasts. The morphology of the lacunae is observed under a scanning electron microscope. The results indicate that Cu2+ at concentration of 1.00 × 10−6 mol/L and 1. 00 × 10−7 mol/L inhibits osteoclastic activity and causes a dose-dependent reduction in the number and surface area of the lacunae. While the number of lanunae is increased and osteoclastic bone resorbing function is significantly improved at Cu2+ concentration of 1.00 × 10−8 mol/L. It is suggested that the effect of Cu2+ on osteoclastic bone resorption depends on Cu2+ concentration. pH had no significant effect on osteoclastic function in the near neutral range.

Comparison of the global air-sea freshwater exchange evaluated from independent datasets

Abstract: The implied air-sea freshwater flux is examined in two reanalysis datasets provided respectively by European Center for Medium-range Weather Forecasts and National Center for Environmental Prediction. Not only for annual mean state but also for seasonal variation, two reanalyses agree qualitatively well with each other, and both can reproduce reasonably the global distribution of E-P (i.e. Evaporation minus Precipitation). In the view of quantitative comparison, however, remarkable difference has been found on regional scales, especially over the middle and lower latitudes, with some local disagreement exceeding 100 cm/yr. One important difference between current and previous evaluation is the new found net evaporation over the high latitude North Atlantic, which is demonstrated to result from the transient disturbances during boreal winter.

Plankton from Early Cambrian black shale series on the Yangtze Platform, and its influences on lithologies

Abstract: Black shales, cherts, and associated lithologies in the Early Cambrian of the Yangtze Platform yielded abundant phytoplankton. the earliest well preserved skeletons of zooplankton (radiolarians) and abundant phosphatic ovoid bodies, probably representing fecal pellets, produced by Mesozooplankton grazing on phytoplankton. The oceanic food chain in surface waters is therefore considered to be more complete than known up to now with respect to primary and secondary consumers in the Early Cambrian plankton ecosystem. On the basis of primary sedimentary compositions preserved in phosphorite concretions and chert layers it is shown that biosiliceous sedimentation mixed with organic substance played a significant role within the black shale sequence of the Hetang and Niutitang formations. The resulting lithology corresponds closely in character to the bituminous Alum-shale and Lydite-sequences of Lower Silurian (Llandoverian) age along northern Gondwana (e. g. Thuringia, Bohemia).

Arthropod trace fossils from the Zhujiaqing Formation (Meishucunian, Yunnan) and their palaeobiological implications

Abstract: Along with several non-arthropod ichnotaxa and rather non-specific scratchmarks. the Upper Phosphate of the Zhujiaqing Formation (Early Meishucunian Stage) in Eastern Yunnan yielded well-preserved resting and digging traces of the Rusophycus-type interpreted as resting traces of unknown large arthropods (ca. 3–6cm in length). The discernible morphological details of these trace fossils enable a rough estimation of the body plan characteristics of the trace originators placing the latter doubtless into the early arthropods, if not euarthropods. The spectrum of the Meishucunian ichnoassemblage. especially the different types of arthropod repichnia point to the existence of a complex benthic ecosystem consisting of animals with different behavioural patterns and life styles already during the earliest Cambrian (Nemakit-Daldyn), and demands the assumption of a longer evolutionary past history of the benthic life on earth before the so-called “Cambrian Explosion” of the metazoans.

Pb-Pb isotope dating of black shales from the Lower Cambrian Niutitang Formation, Guizhou Province, South China

Abstract: The Lower Cambrian black shales of the Niutitang Formation and their lateral equivalents occur widely on the Yangtze Platform. South China. In this study, we examine two sections of the Niutitang Formation in Guizhou Province. We employ a stepwise acid-leaching technique to obtain Pb-isotope compositions of the black shales. At the Zhongnan section, the black shales display large Pb isotope variations, with 206Pb/204Pb of 20.5396–33.5709, and 207Pb/204Pb of 15.8407–16.5782. In contrast, Pb isotope data show a relatively limited range in 206Pb/204Pb (18.2797–18.5972) and 207Pb/204Pb (15.6813–15.7159) at the Zhijin section. Data for all acid-leached black shale samples from the two sections yield a Pb-Pb isochron age of 531 ± 24 Ma. This age may represent the sedimentary age of the black shales. The initial Pb-isotope composition of the black shales fallsnear the upper-crust evolution curve in a Zartman Pb-Pb evolution diagram. Hence, it is likely that the Pb in the black shales may have been deriv...

Silicon-rutile — An ultra-high pressure (UHP) mineral from an ophiolite

Abstract: Silicon(Si)-rutile separated from the Luobusa podiform chromitite in the Yarlung Zangbo ophiolite of southern Tibet is typically about 50 µm × 50 µm × 200 µm in size and consists mainly of SiO2 and TiO2. The average mineral formula is (Ti0.82Si0.18)O2. Powder X-ray diffraction data show that it is tetragonal in form, and the unit cell dimensions and other parameters are: a = 4. 591(2)A, c = 2.946 (2)A, v = 62.09(5)A3, c/a = 0.6415, with a molar volume about 5% smaller than rutile (JCPDS, 21–1276). The Si4+ ions in silicon rutile are six-coordinated, and are substituted for Ti4+ in the rutile structural sites. The Si-rutile, along with other associated ultra-high minerals discovered in the chromitite, such as octahedral silicate, silicon-magnesium spinel (Si4+ ions are six-coordinated), diamond, and intergrown of SiO2 and FeO phases, probably originated from the transition zone or the lower mantle, and were brought to shallow levels beneath an oceanic spreading ridge by an upwelling superplume.

Distribution of possible sunshine durations over rugged terrains of China

Abstract: Based on the digital elevation model (DEM ), a new model for calculating possible sunshine duration (PSD ) is completely described. Using this model, monthly PSD with resolution of 1 km × 1 km for the rugged topography of China is calculated. Results suggest that terrain has robust effect on PSD, particularly in winter when a lower sun elevation angle exists. Besides, the proposed model taking the DEM data as the input has an ability to process mass of data and is applicable to satellite image processing platforms or Geographic Information System (GIS). The PSD (in hours) is provided in the same way as other kinds of spatial information and can be employed as basic geographic data for relevant studies as well.

The occurrence of the genus Marrella (Trilobitoidea) in Asia

Abstract: An important discovery in the Kaili Biota has been made recently, and many interesting components from Chengjiang Biota and Burgess Shale Biota have been discovered. Among them Marrella, only known from mid-Middle Cambrian Burgess Shale Biota of British Columbia, Canada, is one of the most important arthropods fossils. Because the Kaili Biota is older than the Burgess Shale Biota, the strange head shield of Marrella occurring in the Kaili Biota outside Laurentia ranges from mid-Middle Cambrian to early Middle Cambrian and is significant for the reconstruction of palaeogeography and evolutionary study of early metazoa. In the present paper Marrella sp. is reported for the first time in Asia.

Recent progress of deep seismic experiments and studies of crustal structure in northern South China Sea

Abstract: The South China Sea (SCS) is one of the largest marginal seas in the western Pacific. Its northern part has the features of a passive continental margin. The studies of deep crustal structure in this area are very important for understanding the tectonic nature, evolution history, basin formation of the northern margin, and the origin of the SCS. In the past decades, the deep seismic experiments of crustal studies in the northern SCS have gone through three stages, namely the sonobucy, two-ship Expanding Spread Profile (ESP), and Ocean Bottom Hydrophone/Seismometer (OBH/OBS). Along the continental slope, the sonobuoy experiments provided useful information about the velocity structure of the upper crust, while the ESP data recorded for the first time the seismic signals from deep crustal structure and Moho interface. And the OBH/OBS profiles revealed the crustal structure in much greater detail. This paper first gives a brief historical review of these deep seismic experiments and studies, then a summary of the latest progress and important research results. The remaining problems and suggestions for further research work are presented as conclusive remarks.

Size-frequency and rank-frequency relations, power laws and exponentials: a unified approach

Abstract: Power laws, such as Zipf's law, and exponential relations, leading to straight lines in logarithmic or semi-logarithmic scales, are presented in a unified setting. It is shown that the class of size-frequency power laws is larger than the class of rank-frequency power laws. Their ubiquity in all fields of science is illustrated.

Preliminary results and analyses of using IGS GPS data to determine global ionospheric TEC

Abstract: Using the spherical harmonic (SH) function model and the dual frequency GPS data of 139 International GPS Service (IGS) stations for July 15 of 2000, the global ionospheric total electron content (TEC) is calculated and the basic method is investigated. Here, preliminary results are reported and the problems and difficulties to be solved for using GPS data to determine the global ionospheric TEC are discussed.

A new method to dynamically simulate groundwater table in land surface model VIC

Abstract: Soil moisture plays an important role in water and energy balance in land-atmospheric interaction, but is impacted directly by the groundwater table. Dynamic variation of the groundwater tablecan be described mathematically by a moving boundary problem. In this paper, the moving boundary problem is reduced to a fixed boundary problem through a coordinate transformation. A new model of groundwater table simulation is developed using the mass-lumped finite element method and is coupled with the land surface model of Variable Infiltration Capacity (VIC). The simulation results show that the new model not only can simulate the groundwater table dynamically, but also can evade the choice of water table depth scale in computation with a low computation cost.

Composition operators between p-Bloch space and q-Bloch space in the unit ball

Abstract: Let Bn be the unit ball of C n and o = o1 … o n a holomorphic self-map of B n . The main purpose of this paper is to discuss the boundedness and compactness of composition operator Co between p-Bloch space βp Bn and q-Bloch space βqBn … wherep p ⩾0 and q⩾0.

Several key problems in automatic layout design of spacecraft modules

Abstract: Computer-aided layout design of spacecraft modules, such as satellite modules and manned spaceship modules, is of great significance and egregious complexity. It is known as a combinatorial optimization and NPC problem in mathematics a conceptual design and complex system in engineering. The main difficulties include representation and formulation of the problem in mathematics and the solution strategy and pragmatic approaches in engineering practice. After a brief survey of the state-of-the-art in relevant fields, this paper summarizes the research work of the authors' group on automatic layout design of spacecraft modules in the last 15 years, mainly focusing on 5 key problems. They are modeling and problem-solving algorithms, interference calculation, theory and applications of layout topological pattern, decision-making in layout design, and their pragmatic approaches in engineering practice.

A fast SVM training algorithm based on the set segmentation and k-means clustering

Abstract: At present, studies on training algorithms for support vector machines (SVM) are important issues in the field of machine learning. It is a challenging task to improve the efficiency of the algorithm without reducing the generalization performance of SVM. To face this challenge, a new SVM training algorithm based on the set segmentation and k-means clustering is presented in this paper. The new idea is to divide all the original training data into many subsets, followed by clustering each subset using k-means clustering and finally train SVM using the new data set obtained from clustering centroids. Considering that the decomposition algorithm such as SVMlight is one of the major methods for solving support vector machines, the SVMlight is used in our experiments. Simulations on different types of problems show that the proposed method can solve efficiently not only large linear classification problems but also large nonlinear ones.

Pb isotopic geochemical study on the crustal structure of Tongbaishan

Abstract: Pb isotopic composition of the Tongbai complex, distributed in the Tongbaishan to the west of the Dabieshan, ranges between the Dabie core complex and the Dabie ultral-high pressure (UHP) metamorphic complex, the latter having more radiogenic Pb isotopic composition than the former. Granites from the Jigongshan pluton, which intruded mainly into the Tongbai complex, are distinct from the Tongbai complex but similar to the Dabie core complex in Pb isotopic composition, showing that the magma of the Jigongshan granites was derived from the partial melting of the Dabie core complex. According to Pb isotopic compositional variation model in the vertical crustal section and magma source from the Jigongshan pluton, it is suggested that the Tongbai complex was an upper rock serial of the Dabie core complex, which is beneath the Dabie UHP metamorphic complex in the crustal structure of the Tongbai-Dabie orogenic belt. The Tongbai complex was not well preserved in the Dabie area due to the high exhumed crustal section. However, the crustal section in the Tongbai area was exhumed less than that in the Dabie area, and the deep crust in the Tongbai area still contains the basement composition similar to the Dabie core complex. Therefore, the crustal basements from the Dabie to Tongbai areas are united. The present distribution of the basement blocks in different locations of the Tongbai-Dabie orogenic belt reflects different exposure of the crustal section.

Dog sciatic nerve gap repaired by artificial tissue nerve graft

Abstract: The feasibility of repairing dog sciatic nerve damage by using a biodegradable artificial tissue nerve graft enriched with neuroregenerating factors is investigated. The artificial nerve graft was implanted to a 30 mm gap of the sciatic nerve damage in 7 dogs. The dogs with the same nerve damage that were repaired by interposition of the autologous nerve or were given no treatment served as control group 1 or 2, respectively. The observations include gross and morphological observations, immune reaction, electrophysiological examination, fluorescence tracing of the neuron formation and the number of the neurons at the experimental sites, etc. Results showed that 6 months after the implantation of the graft, the regenerated nerve repaired the damage of the sciatic nerve without occurrence of rejection and obvious inflammatory reaction in all 7 dogs, and the function of the sciatic nerve recovered with the nerve conduction velocity of (23.91 ± 11.35)m/s. The regenerated neurons and the forming of a...