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241.
Oliver Lorscheid 《Archiv der Mathematik》2007,88(4):344-348
This paper shows that for a local field K, a subfield k ⊂ K and a variety X over k, X is complete if and only if for every finite field extension Kʹ | K, the set X(Kʹ) is compact in its strong topology.
The author likes to thank Florian Pop, Jakob Stix, Stefan Wewers, Gunther Cornelissen and his own parents for their support.
Received: 13 April 2006 相似文献
242.
Area,coarea, and approximation in <Emphasis Type="Italic">W</Emphasis><Superscript>1,1</Superscript>
David Swanson 《Arkiv f?r Matematik》2007,45(2):381-399
Let Ω⊂ℝ
n
be an arbitrary open set. We characterize the space W
1,1
loc(Ω) using variants of the classical area and coarea formulas. We use these characterizations to obtain a norm approximation
and trace theorems for functions in the space W
1,1(ℝ
n
). 相似文献
243.
In [3] it was shown that a (real) signed measure on a cyclic coarse-grained quantum logic can be extended, as a signed measure,
over the entire power algebra. Later ([9]) this result was re-proved (and further improved on) and, moreover, the non-negative
measures were shown to allow for extensions as non-negative measures. In both cases the proof technique used was the technique
of linear algebra. In this paper we further generalize the results cited by extending group-valued measures on cyclic coarse-grained
quantum logics (or non-negative group-valued measures for lattice-ordered groups). Obviously, the proof technique is entirely
different from that of the preceding papers. In addition, we provide a new combinatorial argument for describing all atoms
of cyclic coarse-grained quantum logics. 相似文献
244.
K Cooper S C Brailsford R Davies 《The Journal of the Operational Research Society》2007,58(2):168-176
Economic evaluation, such as cost effectiveness analysis, provides a method for comparing healthcare interventions. These evaluations often use modelling techniques such as decision trees, Markov processes and discrete event simulations (DES). With the aid of examples from coronary heart disease, the use of these techniques in different health care situations is discussed. Guidelines for the choice of modelling technique are developed according to the characteristics of the health care intervention.The choice of modelling technique is shown to depend on the acceptance of the modelling technique, model ‘error’, model appropriateness, dimensionality and ease and speed of model development. Generally decision trees are suitable for acute interventions but they cannot model recursion and Markov models are suitable for simple chronic interventions. It is further recommended that population based models be used in order to provide health care outcomes for the likely cost, health benefits and cost effectiveness of the intervention. The population approach will complicate the construction of the model. DES will allow the modeller to construct more complex, dynamic and accurate systems but these may involve a corresponding increase in development time and expense. The modeller will need to make a judgement on the necessary complexity of the model in terms of interaction of individuals and model size and whether queuing for resources, resource constraints or the interactions between individuals are significant issues in the health care system. 相似文献
245.
Zuo-liang Xu 《应用数学学报(英文版)》2007,23(4):629-636
In this paper,we study mixed elastico-plasticity problems in which part of the boundary is known,while the other part of the boundary is unknown and is a free boundary.Under certain conditions,this problemcan be transformed into a Riemann-Hilbert boundary value problem for analytic functions and a mixed boundaryvalue problem for complex equations.Using the theory of generalized analytic functions,the solvability of theproblem is discussed. 相似文献
246.
C V Fabritius N L Madsen J Clausen J Larsen 《The Journal of the Operational Research Society》2006,57(12):1482-1490
An ontology is a classification model for a given domain. In information retrieval, ontologies are used to perform broad searches. An ontology can be visualized as nodes and edges. Each node represents an element and each edge a relation between a parent and a child element. Working with an ontology becomes easier with a visual representation. An idea is to use the expressive power of 3D representation to provide visualization for the user. In this paper, we propose a new method for positioning the elements of the visualized concept lattice in the 3D world based on operations research (OR) methods. One method uses a discrete location model to create an initial solution and we propose heuristic methods to further improve the visual result. We evaluate the visual results according to our success criteria and the feedback from users. Running times of the heuristic indicate that an improved version should be feasible for on-line processing and what-if analysis of ontologies. 相似文献
247.
The single-phase diluted magnetic Fe-ion (5%) doped ZnO powders were prepared by solid-state reaction method. The powders were annealed in Ar or Ar/H2(5%) atmosphere at 1200 °C. The crystal structure, electric and magnetic properties for the Zn0.95Fe0.05O powders have been studied with X-ray diffraction (XRD) vibrating sample magnetometer, resistance and Hall measurement. All the peaks for the XRD pattern of samples belong to the hexagonal (P63mc) lattice of ZnO, and no indication of a secondary phase. The lattice parameters for the Zn0.95Fe0.05O with an annealing in Ar/H2(5%) atmosphere were a0=3.256 Å and c0=5.206 Å at room temperature. The hysteresis curve for the Zn0.95Fe0.05O at room temperature was enhanced ferromagnetic behaviour with an annealing in Ar/H2(5%) atmosphere. We give an explanation for enhanced ferromagnetic behaviour with H2 treatment by electric properties. 相似文献
248.
H. Kim R.C.Y. Auyeung M. Ollinger G.P. Kushto Z.H. Kafafi A. Piqué 《Applied Physics A: Materials Science & Processing》2006,83(1):73-76
Low-temperature laser sintering has been successfully demonstrated to improve the overall conversion efficiency of dye-sensitized solar cells. Mesoporous TiO2 electrodes were prepared from a colloidal solution of TiO2 nanopowders by a laser direct-write technique and then sintered by a quasi-continuous-wave UV laser (λ=355 nm) for the fabrication of dye-sensitized solar cells. The overall conversion efficiency of the cells based on the laser-sintered TiO2 electrodes was double that of the devices with non-laser-treated TiO2 electrodes. This enhancement is attributed to both the removal of organic additives and the improved inter-nanoparticle electrical contacts induced by the laser-sintering process, which led to an increase in porosity and dye-absorption sites in the TiO2 electrodes. PACS 61.80.Ba; 61.46.+w; 73.22.-f; 84.60.Jt 相似文献
249.
High-frequency characteristics of CoFeVAlONb thin films were studied. A thin film of Co43.47Fe35.30V1.54Al5.55O9.93Nb4.21 is observed to exhibit excellent magnetic properties; magnetic coercivity of 1.24 Oe, uniaxial in-plane anisotropy field of 66.99 Oe, and saturation magnetization of 19.8 kG. The effective permeability of the film is as high as 1089 and is stable up to 1.8 GHz, and with ferromagnetic resonance over 3 GHz. This film also has very high electrical resistivity of about 628 μΩ cm. These superior properties make it ideal for high-frequency magnetic applications. 相似文献
250.
We study property (T) and the fixed-point property for actions on L
p
and other Banach spaces. We show that property (T) holds when L
2 is replaced by L
p
(and even a subspace/quotient of L
p
), and that in fact it is independent of 1≤p<∞. We show that the fixed-point property for L
p
follows from property (T) when 1<p< 2+ε. For simple Lie groups and their lattices, we prove that the fixed-point property for L
p
holds for any 1< p<∞ if and only if the rank is at least two. Finally, we obtain a superrigidity result for actions of irreducible lattices
in products of general groups on superreflexive spaces.
Bader partially supported by ISF grant 100146; Furman partially supported by NSF grants DMS-0094245 and DMS-0604611; Gelander
partially supported by NSF grant DMS-0404557 and BSF grant 2004010; Monod partially supported by FNS (CH) and NSF (US). 相似文献