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For any natural number n≥1, Y CΩ 2n is an easy term; that is, for any λ term M, λβ+Y\-CΩ 2n =M is consistent, where Y C is Curry fixed point combinator, Ω 2n ≡ω 2n ω 2n and ω 2n ≡λx.xx...x (there are 2n occurrences of x after λx ). This result is a partial solution to Jacopini's conjecture: Y CΩ n is an easy term for any natural number n≥2.  相似文献   

3.
The purpose of this paper is to discuss the symplectic transformation laws on the theta series and give an explicit formula for the trace of the symplectic operator.  相似文献   

4.
LU Jun 《自然科学进展》2007,17(2):144-149
The rigorous solutions of the stationary Schr?dinger equation for hydrogen atom are solved with the wave-mechanics method within the framework of the quantum phase-space representation established by Torres-Vega and Frederick. The “Fourier-like” projection transformations of wave function from the phase space to position and momentum spaces are extended to three-dimensional systems. The eigenfunctions in general position and momentum spaces could be obtained through the transformations from eigenfunction in the phase space.  相似文献   

5.
A minimizing problem for quadratic functionals in Hilbert spaces is studied. A necessary and sufficient condition for well-posedness is given, and the condition for solvability is also proved.  相似文献   

6.
A formal deductive system for fuzzy propositional calculus   总被引:10,自引:0,他引:10  
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7.
As one of the most important groups in micropaleontology, Foraminifera is traditionally described to have a membranous, agglutinated or carbonate shell according to its morphology, which resembles the marine granuloreticuloseans. However, recent molecular analyses on its ribosomal RNA gene have disclosed the existence of the naked, and also freshwater and terrestrial species. Foraminiferal SSU rDNA sequence suggests that this group is positioned at the base of the Eukaryotes phylogenetic trees, between Euglenoida and Diplomonadida. Existence of a large amount of genetic types in planktonic foraminifera suggests an underestimation of the biodiversity for the nearly 50 species in world oceans and their close relationship with the ocean environment, such as bio-geographic distribution and water currents. This provides a more reliable proxy for future paleoenvironmental study.  相似文献   

8.
A new linguistic granular model is proposed and the effect of its parameters on the output is analyzed. The design of the model consists of two stages: using conditional fuzzy clustering for information granular, and integrating all information granules to final output. The integrating tool is fuzzy integral based on fuzzy measure, and the generalization of fuzzy integral increases flexibility of the linguistic granular model greatly. A heuristic algorithm to determine the parameters in the fuzzy integral is used to realize the linguistic model. Two experiments verify the feasibility of the proposed model.  相似文献   

9.
An effective noise removal algorithm which does not cause the shrinkage of surface is presented. By introducing the constraints of keeping all triangle barycenters invariant al each smoothing step, the algorithm turns the problem of mesh fairing into a constrained minimization of the energy functional, which is then solved efficiently by our iterative method. Experimental results demonstrate that our algorithm not only can preserve the good shape of the original surface while quickly removing the noise, but also has the advantages of fast convergence, low computational cost and stable performance.  相似文献   

10.
Based on the researches of the Mesozoic thermal evolution history, the deformed structures, and fission track analysis of the Zhangjiakou-Xuanhua area, we obtained the following knowledge: the area experienced in 140 Ma an underplating which is marked by emplacement of mantle derived magma; during 130—110 Ma a series of eruptions and intrusions happened, and during 80—10 Ma a rising process occurred which is synchronous with the adjacent Taihang and Yanshan Mountains and was accompanied by a series of structures down slipping from the just formed Zhang-Xuan uplift toward its periphery. Combining the Zhang-Xuan thermal lift with the large detachment structure in Baoding depression of the North China Basin in the Late Mesozoic confirms that an even larger extensional tectonic background existed in North China during this period.  相似文献   

11.
Mercury(Hg) is a toxic heavy metal with its biogeochemical cycling in the ocean depending on the type and behavior of the oceanic microalgae.The present work aimed to evaluate bioaccumulation and transformation of Hg by Phaeodactylum tricornutum,a typical unicellular diatom,when exposed to the extremely high level of Hg in order to understand the possible mechanisms of acute stress response.P.tricornutum can accumulate Hg(its bioaccumulation factor is at 104 level),and the 96 h EC 50 was estimated to be 145μg L-1.The amounts of surface-bound Hg being about 1.2 to 4.8 times higher than those of intracellular Hg under exposure to HgCl 2(from 20 to 120μg L-1 concentrations) suggested that the cell wall of P.tricornutum is an important "fence" towards Hg.After entering the P.tricornutum cell,Hg underwent transformation in its chemical form via interactions with high molecular weight sulfur-containing proteins(accounting for 68% of the intracellular Hg),and glutathione as well as the induced phytochelatins(PCs)(24% Hg) which alleviated the toxicity of HgCl2.In addition,the existence of organic ligands greatly influenced the uptake and transformation behavior of P.tricornutum towards HgCl2,especially in the case of cysteine(Cys),which increased the uptake of Hg,but alleviated the toxicity of Hg towards P.tricornutum due to the fact that Cys is an important precursor for the synthesis of PCs inside the cell.The uptake process of Hg by P.tricornutum was in agreement with the Freundlich isotherm,suggesting a typical heterogeneous sorption process.More importantly,we observed the conversion of HgCl2 into methylmercury inside the P.tricornutum cells and its release into the culture solution using HPLC/CVG-AFS and GC-MS,although the mechanism needs to be further investigated.  相似文献   

12.
A novel scheme of external force for detecting the object boundary of medical image based on Snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our Snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent Snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.  相似文献   

13.
A polycistronic expression vector, pKGA-NTF1, was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002 chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3 gene (NTF1) to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1 gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.  相似文献   

14.
Rapid progress in high-throughput biotechnologies (e.g. microarrays) and exponential accumulation of gene functional knowledge makes it promising for systematic understanding of complex human diseases at the functional modules level. Current modular categorizations can be defined and selected more specifically and precisely in terms of both biological processes and cellular locations, aiming at uncovering the modular molecular networks highly relevant to cancers. Based on Gene Ontology, we identifed the functional modules enriched with differentially expressed genes and characterized by biological processes and specific cellular locations. Then, according to the ranking of the disease discriminating abilities of the pre-selected functional modules, we further defined and filtered signature modules which have higher relevance to the cancer under study. Applications of the proposed method to the analysis of a prostate cancer dataset revealed insightful biological modules.  相似文献   

15.
Rapid progress in high-throughput biotechnologies (e.g. microarrays) and exponential accumulation of gene functional knowledge makes it promising for systematic understanding of complex human diseases at the functional modules level. Current modular categorizations can be defined and selected more specifically and precisely in terms of both biological processes and cellular locations, aiming at uncovering the modular molecular networks highly relevant to cancers. Based on Gene Ontology, we identifed the functional modules enriched with differentially expressed genes and characterized by biological processes and specific cellular locations. Then, according to the ranking of the disease discriminating abilities of the pre-selected functional modules, we further defined and filtered signature modules which have higher relevance to the cancer under study. Applications of the proposed method to the analysis of a prostate cancer dataset revealed insightful biological modules.  相似文献   

16.
ItiswellknownthattheBergman ,Carath啨odory ,KobayashiandEinstein K hlermetricsarefourclassicalinvariantmetricsincomplexanaly sis .TheBergmanmetric(denotedbyB)wasintro ducedbyBergmanforone[1] in 192 1orseveralvari ables[2 ] in 1933.Carath啨odoryintroducedtheinvari antdistancein 192 6 [3] andReiffenintroducedthein variantmetricin 196 3[4 ] ,thereforetheCarath啨odorymetric (denotedbyC)isalsocalledCarath啨odory Reiffenmetric .TheKobayashimetric (d…  相似文献   

17.
The diagnosis of prostate diseases by magnetic resonance imaging (MRI) in vivo is sometimes difficult for the lower signal to noise ratio (SNR). To increase the SNR of the prostate image, we designed a RF coil that can be inserted into rectum and was named endorectal coil. The properties of RF coil were evaluated using a network analyzer. Moreover the images and spectroscopy of a special phantom were acquired and the results were compared to those of the commercial TORSO coil (G.E. Medical Systems, USA). Our coil gave a significantly higher SNR at the region of interest (ROI). The achieved high local SNR and resulting high spatial resolution would add more anatomic and biochemical information to the diagnosis of prostate diseases.  相似文献   

18.
In order to investigate the mechanisms of enhanced UV-B radiation on algae, the effects of UV-B radiation on the physiological and ultrastructural changes of Chlorella sp. were examined. The results showed that UV-B radiation could inhibit the growth and photosynthesis of microalgae. UV-B radiation at lower doses increased the photosynthetic pigment (chlorophyll a (Chla) and carotenoid (Car)) contents, while at higher doses of UV-B radiation Chla and Car contents were decreased. The ultrastructure of Chlorella sp. without exposure to UV-B showed that the thylakoid lamellae were clear and regular, the stroma of its chloroplast was apparent and clear. The globules with photosynthetic pigments and the cristae of mitochondria were clearly seen. After exposure to UV-B radiation at dose of 2.88 kJm2, the thylakoid lamellae of Chlorella sp. were lost and dissolved, the globules which contained photosynthetic pigments in chloroplast were bleached; some mitochondria cristae were dissolved; slight plasmolysis was found in some Chlorella sp. cells. After exposure to 5.76 kJm2 UV-B radiation, the thylakoid was in disarray and disintegration, plasmolysis was found in most cells, and the cell wall was broken and began to fall out. Many blank areas were observed in cells, mitochondria were seriously deformed and most of the mitochondria cristae were dissolved. Also, globules containing photosynthetic pigments in chloroplast were bleached and some empty globules were found in chloroplast. Therefore, UV-B radiation could damage cell structure of Chlorella sp., and this damage increased with the dose of UV-B radiation they exposed to.  相似文献   

19.
Numerical modelling of a turbulent bluff-body flow has been performed using differential Reynolds stress models (DRSMs). To clarify the applicability of the existing DRSMs in this complex flow, several typical DRSMs, including LRR-IP model, JM model, SSG model, as well as a modified LRR-IP model, have been validated and evaluated. The performance difference between various DRSMs is quite significant. Most of the above mentioned DRSMs cannot provide overall satisfactory predictions for this challenging test case. Motivated by the deficiency of the existing approaches, a new modification of LRR-IP model has been proposed. A very significant improvement of the prediction of flow field is obtained.  相似文献   

20.
Based on the distributions of stress and free charge on the interface of the surface acoustic wave (SAW) device calculated with the combination of boundary element method and finite element method(FEMBEM), the power of each of the three possible bulk waves radiated by the SAW device is calculated, and their contributions to the overall input conductance are separated respectively. Moreover, the formula of angular distributions of their power radiation into the substrate is derived. Consider the effect of mass loading, the resistance density,defined as a scalar, is extended to generalized resistance densities which can be written as three 4×4 tensors and for which the formulas are derived. The bulk wave radiations for a synchronous one-port resonator on 42°Y-rotated LiTaO3 are simulated. It is found that the radiated energy by slow shear wave contributes a very high proportion to input electrical energy in some frequency range.  相似文献   

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