Showing papers by "Academia Sinica published in 1984"
Abstract: An artificial boundary condition at the edge of finite computational grids is devised. Itcan simulate the transmitting process of clastic surface waves and body waves incident atarbitrary angles under any accuracy required. It may be used for two- or three-dimensionaltransient wave analyses in laterally heterogeneous media and easily incorporated into exist-ing finite element or finite difference computational codes.
606 citations
TL;DR: A new collection of nearly 500 samples from a natural outcrop and a borehole section near Lochuan (lat. 35.8°N, long. 109.2°E; Shaanxi province) has been dated by magnetic stratigraphy as discussed by the authors.
Abstract: Summary.
The age of Chinese loess deposits has long been disputed. Biostratigraphical and earlier magnetostratigraphical investigations placed the entire loess formation within the Pleistocene and ascertained a maximum loess age of about 1.2 Myr. A new collection of nearly 500 samples from a natural outcrop and a borehole section near Lochuan (lat. 35.8°N, long. 109.2°E; Shaanxi province) has been dated by magnetic stratigraphy. Thermal cleaning of the natural remanent magnetization (NRM) removes a strong secondary component of viscous origin along the present geomagnetic field which resides largely in magnetite. The characteristic NRM component is due to haematite which is thought to be of chemical origin. Rhythmical intensity variations of NRM and initial susceptibility depend on the loess lithology and may reflect climatic changes during loess deposition.
The palaeomagnetic results are consistent between the two sections and yield a clearly defined magnetic polarity zonation. The Brunhes-Matuyama boundary and the Jaramillo subchron have been positively identified in both outcrops at exactly the same stratigraphic level. The Olduvai subchron has been found in the borehole section which records the entire loess sequence. Most probably the formation of Chinese loess began shortly after the Matuyama-Gauss polarity transition. Therefore a late Pliocene age of about 2.4 Myr is assigned to the oldest loess sediments measured.
496 citations
TL;DR: In this article, a series of different plutons from the Lhasa-Xigaze segment of the Gangdese (Transhimalaya) belt has been studied by high-resolution U Pb analyses of zircon.
265 citations
TL;DR: In this article, wide angle reflection profiles of the crust-mantle boundary south of the Yarlung Zangbo suture in Tibet reveal a deep (70 km) Moho extending north from the High Himalayas, whilst to the south the Moho is 15 km higher.
Abstract: Reversed critical wide angle reflection profiles of the crust–mantle boundary south of the Yarlung Zangbo suture in Tibet reveal a deep (70 km) Moho extending north from the High Himalayas, whilst to the south the Moho is 15 km higher. Even further south, reflections from 35 km depth may correspond to the Moho of peninsular India.
218 citations
TL;DR: A fan-profile through the Yarlung Zangbo suture, across the Lhasa block and through the Bangong-Nujiang suture shows several significant and sharp changes in crustal thickness as mentioned in this paper.
Abstract: A north–south wide-angle fan-profile through the Yarlung Zangbo suture, across the Lhasa block and through the Bangong-Nujiang suture shows several significant and sharp changes in crustal thickness. Both sutures appear as vertical 20-km steps in the Moho and may have been the loci for eastward strike-slip motion of the Tibetan lithosphere.
180 citations
TL;DR: Results indicate that a compact globular conformation, similar to that observed in turkey pancreatic polypeptide may be adopted by all molecules and that this may be more highly conserved than the individual amino acid sequences.
Abstract: Pancreatic polypeptide has been extracted and sequenced from a wide range of species. The 36-residue polypeptides have some hormonal characteristics, and show a high degree of sequence homology. Two recently isolated polypeptides, from porcine gut and brain, also show a high degree of sequence homology with the pancreatic polypeptides. It was proposed that these polypeptides were members of a related family. The X-ray determined structure of one member of the family, turkey pancreatic polypeptide, is known to high resolution, but there is no structural information for the others. Studies designed to give an insight into the tertiary structure of these related molecules have been carried out, including model building using interactive computer graphics, circular dichroic spectroscopy and secondary structure prediction using a variety of algorithms. The results indicate that a compact globular conformation, similar to that observed in turkey pancreatic polypeptide may be adopted by all molecules and that this may be more highly conserved than the individual amino acid sequences.
174 citations
TL;DR: In this article, the first eigenvalue of the Laplace operator of satisfaction λ 1 ≈π 2 for a compact Riemannian manifold with non-negative Recci curvature was proved.
Abstract: The main theorem proved in this work is: Let M be a compact Riemannian manifold withnon-negative Recci curvature, then the first eigenvalue -λ1, of the Laplace operator of Msatisfies λ1≥π2, where d denotes the diameter of the M. This estimate improves the recentresults due to S. T. Yan and P. Li and gives the best estimate for this kind of manifold
171 citations
TL;DR: In this paper, a numerical method for transmitting waves out of an artificial boundary is presented, which is applicable to linear two-or three-dimensional wave problems with a time-stepping algorithm and a convex artificial boundry.
159 citations
TL;DR: In this paper, heat flow measurements have been attempted in two freshwater lakes at altitudes of 4.5 and 5.0 km, south of the Yarlung-Zangbo suture zone in southern Tibet.
Abstract: Heat flow measurements have been attempted in two freshwater lakes at altitudes of 4.5 and 5.0 km, south of the Yarlung–Zangbo suture zone in southern Tibet. Probe penetration in the lake sediments was deep enough in the case of eight measurements (5.5–7.2 m) to give reliable temperature gradients. Corrections for seasonal temperature variations, topographic and refraction effects have been applied to the data. In a north–south profile trending perpendicular to the Yarlung–Zangbo suture zone, heat flow is approximately constant at 146 mWm−2 over a distance of 30 km and drops to a value of 91 mW m−2 in <25 km. The high heat flow and the sharp spatial variation both suggest the existence of a heat anomaly located at relatively shallow depths (no greater than 25 km) in the Tibetan crust, probably due to the recent emplacement of plutonic bodies.
159 citations
TL;DR: The methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods that are the prerequisite for the necessary improvements of the material properties of UHMW PE.
Abstract: In this study it is demonstrated that the combined chemical and mechanical influences of the implant situation cause property changes of ultra-high-molecular-weight polyethylene (UHMW PE) hip joint cups. Nearly 30 out of 48 loosened cups, retrieved 3 weeks to 11 years after implantation, were investigated. Density measurements show a density increase with implantation time and a dependence of these changes from implant position and loading conditions. The rate of extractable constituents also increases with course of time. An increased in vivo conditioned oxidation of the UHMW PE can be demonstrated by infrared (IR) spectrometry. The density increase can be explained by post-crystallization, which is the result of oxidative chain scission. This leads to a reduction of the average molecular weight of the PE and to an increased extractability of constituents. Since these changes have been recognized as the reasons for aging and failing of UHMW PE, the methods of material characterization used in this study for retrieved implants will help to develop suitable in vitro testing and simulating methods. They are the prerequisite for the necessary improvements of the material properties of UHMW PE.
152 citations
TL;DR: The Pb isotopic study of the Xigaze ophiolite (Tibet) showed that the tectonic (harzburgites) and magmatic (gabbros, dolerites, lavas) units bear different isotopic signatures, the harzburgitic rocks show much higher207Pb/204Pb values than the samples from the magmatic unit.
TL;DR: The search for additional sex pheromone components was prompted by the previous identification of unusual fatty acyl moieties in the gland that seemed to be possible biosynthetic intermediates.
Abstract: In addition to the previously identified components (Z)-7-dodecenyl acetate and dodecyl acetate, sex pheromone glands ofTrichoplusia ni release (Z)-5-dodecenyl acetate, 11-dodecenyl acetate, (Z)-7-tetradecenyl acetate, and (Z)-9-tetradecenyl acetate. Bioassays in a flight tunnel showed that a synthetic blend of these six compounds elicited complete flights to the source from 95% of the males tested and elicited hairpenciling responses at the end of the flights from 88% of the males tested. This blend was not significantly different from intact pheromone glands, which elicited complete flights to the source from 98% of the males tested and hairpenciling responses from 91% of the males tested. In contrast, the previously identified two-component blend elicited significantly fewer complete flights to the source (33%) and did not elicit hairpenciling responses from any of the males tested. The search for additional sex pheromone components was prompted by our previous identification of unusual fatty acyl moieties in the gland that seemed to be possible biosynthetic intermediates.
01 May 1984
TL;DR: In this paper, the front tracking method is applied to the Euler equations describing compressible gas dynamics, and the results on a series of test problems for which comparison answers can be obtained by independent methods.
Abstract: Front tracking is an adaptive computational method in which a lower dimensional moving grid is fitted to and follows the dynamical evolution of distinguished waves in a fluid flow. The method takes advantage of known analytic solutions, derived from the Rankine-Hugoniot relations, for idealized discontinuities. In this paper the method is applied to the Euler equations describing compressible gas dynamics. The main thrust here is validation of the front tracking method: we present results on a series of test problems for which comparison answers can be obtained by independent methods.
TL;DR: In this article, a flow-injection system combines on-line ion exchange preconcentration with atomic absorption spectrometry (a.a.s.) for the determination of traces (μg l −1 ) of heavy metals in water samples.
TL;DR: The hemolymph ecdysteroids of brainless Samia pupae that were developed by PTTH injection increased with essentially the same pattern as in developing normal pupae.
TL;DR: In this paper, the main topological types of global structure of trajectories for this class of differential equations are studied, and a simple criterion to determine to which type any concrete differential system belongs is also given.
TL;DR: In this article, it was shown that the partition function of the Ising model is the generating function of bond-correlated percolation model (BCPM) with a bond probability $p=1.
Abstract: The phase transition in the Ising model and the percolation transition in the lattice percolation model have many common characteristics which have motivated researchers to explore whether the former is a percolation transition of a correlated percolation model. Previous attempts to draw such a connection have been either unsuccessful or unsatisfactory. Considering each lattice site with an Ising spin occupied and the nearest-neighbor (NN) coupling between occupied sites as a bond with a bond probability $p$ depending on the NN coupling constant $J$ and the temperature $T$, we formally show that the partition function of the Ising model is the generating function of bond-correlated percolation model (BCPM) with a bond probability $p=1\ensuremath{-}\mathrm{exp}(\frac{\ensuremath{-}2J}{\mathrm{kT}})$. The BCPM has the Ising critical temperature and exponents, including $\ensuremath{
u},{\ensuremath{
u}}^{\ensuremath{'}},\ensuremath{\eta},\ensuremath{\beta},\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}$, and $\ensuremath{\gamma}$ (perhaps also ${\ensuremath{\gamma}}^{\ensuremath{'}}$). From the connection between the Ising model and the BCPM, we also derive and hence give a geometrical meaning of the finite-size scaling and broadening at first-order phase transitions of the Ising model. Our approach may easily be extended to many spin models and give geometrical meaning to other properties of spin models.
TL;DR: In this article, potato II medium was tested against B 5 medium for their ability to induce pollen callus in anther culture of a hexaploid triticale Beagle and two F 1 hybrids between Beagle × Kedong No. 58.
TL;DR: In this article, the authors present the first quantitative results on the rate of production of solid residues, obtained by bombarding thick (l019−1020C atoms cm−2) frozen layers (T≍4K) of methane with 1.5-MeV protons produced at the Catania University van de Graaff accelerator.
Abstract: There has recently been much experimental and theoretical interest among astrophysicists in the synthesis of complex organic materials (polymers) as a consequence of the energy deposition by external agents on carbon-containing molecular solids such as CH4, C2H6, C3H8, C6H6 and mixtures with CO2, CO, NH3 and H2O. Solid residues have been obtained by bombardment of hydrocarbon rich frozen layers with UV photons1 and energetic particles2–4. We present here the first quantitative results on the rate of production of solid residues, obtained by bombarding thick (≍l019–1020C atoms cm−2) frozen layers (T≍4K) of methane with 1.5-MeV protons produced at the Catania University van de Graaff accelerator. This process converts the methane molecules to a polymer-like residue which is stable at room temperature and above. The thickness of the solid residues has been measured both in situ by elastic proton scattering (in C atoms cm−2) and remotely, by talysurf measurements (in μm). Thicknesses of up to 15 μm or 3.1 × 1019 C atoms cm−2 have been measured and the density of the residues is ρ ≥ 0.5 g cm−3. The process appears to occur along the entire path of the incoming protons.
TL;DR: The range of stages at which the anthers were productive varied with genotypes, however, calli and plantlets were obtained from an Ethers at pollen mother cell to trinucleate stage in two F1 hybrids.
TL;DR: In this paper, the morphology and properties of binary blends of isotactic polypropylene (PP) with EPT (EPT/PP) and ternary blends of PP, EPT, and polyethylene (PE) were analyzed.
Abstract: Great attention has been paid to the toughening of isotactic polypropylene (PP) in recent years in order to make full use of this plastic. This paper presents the results of our study on the compatibility of PP with ethylene-propylene-diene rubber (EPT), polybutadiene rubber (PB) or styrene-butadiene rubber (SBR) through characterization of the blends' morphology, and on. the morphology and properties of binary blends of PP with EPT (EPT/PP) and ternary blends of PP, EPT, and polyethylene (PE) (EPT/PE/PP). Morphological structure of solution blends and the great improvement in low-temperature impact strength and other properties of the mechanical blends have shown the difference among EPT, PB, and SBR in compatibility with PP, the effectiveness of using EPT as PP's toughening agent, and the effect of EPT on EPT/PP blend as both toughening agent and compatibilizer. Addition of EPT to EPT/PP made interesting changes in morphology but no effect on properties was observed.
TL;DR: The term herbal medical seaweeds as the authors use here applies to those which the Chinese people have collected and utilized, generally by boiling in water and using the decoction as drugs, and those which are found in Chinese herbal drug stores.
Abstract: For ages, the Chinese people have been utilizing seaweeds for various medicinal purposes and early records of herbal medical seaweeds appeared in Chinese literature about two thousand years ago. The term herbal medical seaweeds as we use here applies to those which our people have collected and utilized, generally by boiling in water and using the decoction as drugs, and those which are found in Chinese herbal drug stores. For instance in Guangzhou (Canton) and Hong Kong one can readily purchase in local herbal drug stores, ‘Haicao’ (locally pronounced ‘Hoizo’) and ‘Kunpu’ (locally pronounced ‘Guanbo’), respectively Sargassum spp. especially S.fusiforme(Harv.) Setch., and Ulva lactuca L. According to Tseng & Chang (1952), there are 12 genera including 20 species of seaweeds which are of economic value in North China. Two species and two genera of seaweeds are used in herbal medicine: Laminaria japonica Aresch. and Sargassum fusiforme, Porphyra spp. and Ulva spp., of which the first two species were effective for curing goiter, scrofula and dropsy for more than 20 centuries according to the ancient literature in China.
TL;DR: In this paper, the optimal spraying parameters of various wear-resistant ceramic and cermet coatings are briefly described and the relationship between wear damage and their microstructure, physical properties and especially their thermal diffusivity is discussed.
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TL;DR: This article gave a general criterion for normality which includes the criteria due to Miranda, Valiron, Chuang and Ku respectively (cf. [1, 4] and This article ).
Abstract: In this talk, we will give a general criterion for normality which includes the criteria due to Miranda, Valiron, Chuang and Ku respectively (cf. [1,4]).
TL;DR: In this paper, the β-D-glucosyl ester of 13-O-Dglocosyl-steviol which was isolated from leaves of Rubus suavissimus collected in China as the major sweet principle (yield: 5.4%), was subjected to α-1 4 transglucousylation with the cyclodextrin glucosyltransferase produced by Bacillus megaterium Strain No. 5 using soluble starch as a donor.
Abstract: Rubusoside, the β-D-glucosyl ester of 13-O-D-glucosyl-steviol which was isolated from leaves of Rubus suavissimus collected in China as the major sweet principle (yield: 5.4%), was subjected to α-1 4 transglucosylation with the cyclodextrin glucosyltransferase produced by Bacillus megaterium Strain No. 5 using soluble starch as a donor. A significant improvement in the quality of sweetness was observed for the crude reaction mixture, which was separated into mono-, di-, tri-, tetra-, penta-, and hexa-glucosylated products. All isomers of the mono- and di-glucosylated products were further separated. Evaluation of the sweetness of these products compared with stevioside, rebaudioside A, etc. disclosed that the ratio of the number of glucose units at the 13-hydroxyl group to that at 19-carboxyl group seems to have a significant relationship with the sweetness as well as the quality of taste for glucosides of this type.
TL;DR: The relatively low prevalence of lactose malabsorption among the Kazakhs suggests that lactose persistence may be frequent in herding pastoralist populations of southwest Asia.
Abstract: Lactose absorption capacity was examined in 641 apparently healthy adolescents and adults (447 males and 194 females with an average age of 22.9 years and an age range of 16-46 years) using a field version of the lactose tolerance test with breath hydrogen determination. In the total sample, 89 lactose absorbers and 552 lactose malabsorbers were identified. Lactose malabsorption was most frequent in a subgroup of Han (Chinese) from northeastern China (229 of 248 subjects, 92.3%). Among 198 Mongols from Inner Mongolia, there were 174 lactose malabsorbers (87.9%). The frequency of lactose malabsorption was lowest in a group of Kazakhs, traditional herders from the northwestern region of Xinjiang (149 of 195 subjects, 76.4%). Reported symptoms of lactose intolerance were significantly more frequent in lactose malabsorbers. The findings in northern Han are similar to the reported lactose malabsorption frequency in southern (mainly overseas) Chinese, and correspond with the absence of animal milk from traditional Chinese diets. The relatively low prevalence of lactose malabsorption among the Kazakhs suggests that lactose persistence may be frequent in herding pastoralist populations of southwest Asia.
TL;DR: The Late Ordovician paleogeographic changes in the Yangtze Platform indicate a widespread regression and consequent subaerial exposure probably caused by the locking up of substantial amounts of marine waters during the Late Ondovician glaciation as discussed by the authors.
Abstract: The Late Ordovician paleogeographic changes in the Yangtze Platform indicate a widespread regression and consequent subaerial exposure probably caused by the ‘locking up’ of substantial amounts of marine waters during the Late Ordovician glaciation. The subsequent rapid paleogeographic changes on the Yangtze Platform during the earliest Silurian suggest a rapid melting of the ice. The relatively cool waters in the partially closed Yangtze basin during the latest Ordovician were replaced by open and warm waters during the earliest Silurian. Sedimentation rates and composition of faunal assemblages underwent marked changes during latest Ordovician and Early Silurian. Glaciation, Ordovician, Silurian, Paleogeography, sedimentary rate, faunal change.
TL;DR: The new order of aves, Gansuiformes, is established on the basis of the fossil specimens, including a tibiotarsus and a tarsometatarsus with four complete digits derived from the LowerCretaceous of Yumen, GANSu Province, which probably represents the oldest one incontinental deposits.
Abstract: The new order of aves, Gansuiformes, is established on the basis of the fossil specimens,including a tibiotarsus and a tarsometatarsus with four complete digits derived from the LowerCretaceous of Yumen, Gansu Province. The new bird probably represents the oldest one incontinental deposits. As Archaeopteryx is now considered as the ancestor of all landbirds,Gansus, the new bird is supposed to be the ancestor of shorebirds and waterbirds. Gansui-formes is similar to Charadriformes and some waterbirds in certain characters.
TL;DR: In this article, a two dimensional autoregressive moving average spatial model is used to analyse spatial interaction and maximum likelihood estimates of the unknown parameters are derived as the solution of a system of nonlinear equations, and are shown to be best asymptotic normal.
Abstract: Summary
A two dimensional autoregressive moving average spatial model is used to analyse spatial interaction. Maximum likelihood estimates of the unknown parameters are derived as the solution of a system of nonlinear equations, and are shown to be best asymptotic normal. One important computational procedure is discussed. The argument is extended to the general regression model with autoregressive moving average residuals. Explicit computational formulae are given.