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881.
882.
An ω-tree-automatic structure is a relational structure whose domain and relations are accepted by Muller or Rabin tree automata.
We investigate in this paper the isomorphism problem for ω-tree-automatic structures. We prove first that the isomorphism relation for ω-tree-automatic boolean algebras (respectively, partial orders, rings, commutative rings, non commutative rings, non commutative
groups, nilpotent groups of class n ≥ 2) is not determined by the axiomatic system ZFC. Then we prove that the isomorphism problem for ω-tree-automatic boolean algebras (respectively, partial orders, rings, commutative rings, non commutative rings, non commutative
groups, nilpotent groups of class n ≥ 2) is neither a Σ21-set nor a Π21-set. 相似文献
883.
884.
Nada Miljević Dusan Golobočanin Nives Ogrinc Ana Bondžić 《Isotopes in environmental and health studies》2013,49(2):137-148
Stable hydrogen and oxygen isotopes were analysed in water samples from the River Danube and its tributaries during a longitudinal survey performed in August 2005 on Serbian territory. Danube river water data ranged from?80‰ to?66‰ for δ2H, and from?11.2‰ to?9.3‰ for δ18O with δ values increasing downstream. The isotopic signatures of the adjacent tributaries (the Tisza, the Sava and the Velika Morava) sampled at the locations close to their confluence with the Danube (Titel, Ostru?nica and Ljubi?evski most, respectively) just about the time of the campaign were enriched (?67‰ and?63‰ for δ2H, and?9.3‰ and?8.9‰ for δ18O) with respect to the Danube water because of their catchment effects. Hydrogen and oxygen stable isotope values were used in combination with measured physico-chemical and biological parameters to trace hydrological and transport processes in these river systems. The mixing relationships between the Danube main stream and its tributaries were estimated using the mass balance for isotopic composition and electrical conductivity as conservative parameters. Evidence of an incomplete mixing process at the ?enta location, 8 km below the confluence of the Tisza river, with its participation of 88% was shown by its oxygen-18 content. The correlations between river water isotope composition and physico-chemical and biological parameters are discussed. 相似文献
885.
Une nouvelle enceinte destinée à la production de l,or colloïdal radioactif198Au à usage thérapeutique et diagnostique est construite dans le Laboratoire de Chimie de Haute Activité à l'Institut des Sciences Nucléaires ?Boris Kidri?”. L'enceinte comporte deux appareils pour la préparation des colloïdes de l'or radioactif, permettant une production permanente méme au cas où l'un des appareils est accidenté. C'est grâce à une conception originale de la protection en plomb que l'accès aus appareils et aux stocks des effluents est rendu facile et ainsi que les systèmes de commande des processus des processus chimiques et la manipulation dans l,enceinte sont bien simplifiés 相似文献
886.
R. S. Drašković J. Bzenić M. Ratković R. J. Drašković 《Isotopes in environmental and health studies》2013,49(8):290-293
Stability of radioactive sodium ortho-131I-hippurate produced at the Boris Kidri? Institute, Vin?a, according to the modified procedure for application in nuclear medicine in Yugoslavia was investigated. In these investigations stability was observed as a function of the ageing time of the solutions, their radioactivity (A mCi/ml; A mCi/mg of the carrier; Atot), the presence of some bacteriostatics and stabilizers (C6H5—CH2OH, Na-citrate), sterilization process and storage conditions. 相似文献
887.
The aim of this paper is to show that the procedure of maximum entropy principle for the closure of the moments equations for rarefied monatomic gases can be extended also to polyatomic gases. The main difference with respect to the usual procedure is the existence of two hierarchies of macroscopic equations for moments of suitable distribution function, in which the internal energy of a molecule is taken into account. The field equations for 14 moments of the distribution function, which include dynamic pressure, are derived. The entropy and the entropy flux are shown to be a generalization of the ones for classical Grad’s distribution. The results are in perfect agreement with the recent macroscopic approach of extended thermodynamics for real gases. 相似文献
888.
The widespread use of gas discharge tubes (GDTs) and avalanche diodes for transient voltage suppression (TVS) in many cases results in their exposure to ionizing radiation. The aim of this paper is to investigate the influence of irradiation on these TVS devices’ characteristics, by exposing them to a combined neutron/gamma radiation field. Experimental results show that irradiation of TVS diodes causes a lasting degradation of their protective characteristics. On the other hand, GDTs exhibit a temporary change of performance. The observed effects are presented with the accompanying theoretical interpretations, based on the interaction of radiation with materials constituting the investigated devices. 相似文献
889.
Sanja Marušić 《Applicable analysis》2013,92(3-4):379-401
Using the homogenization theory, we derive the nonlinear Reynolds equation governing the process of lubrication of a slipper bearing with rapidly rotating shaft. We prove that this nonliner lubrication law is an approximation of the full Navier-Stokes equations in a thin cylinder with periodic roughness. The analyticity of the nonlinear function giving the relation between the velocity and the pressure drop is proved. The first term in its Taylor's expansion is the classical linear Reynolds law. Boundary layer correctors are computed. 相似文献
890.
Goran Djanković 《Czechoslovak Mathematical Journal》2013,63(3):833-845
Classical Kloosterman sums have a prominent role in the study of automorphic forms on GL2 and further they have numerous applications in analytic number theory. In recent years, various problems in analytic theory of automorphic forms on GL3 have been considered, in which analogous GL3-Kloosterman sums (related to the corresponding Bruhat decomposition) appear. In this note we investigate the first four power-moments of the Kloosterman sums associated with the group SL3(?). We give formulas for the first three moments and a nontrivial bound for the fourth. 相似文献