Characterization of microwave plasma generated in inhomogeneous magnetic field

The paper is devoted to the investigation of the electron cyclotron resonance (ECR) discharge in the decreasing magnetic field in the pressure range from 0.02 Pa to 90 Pa and the absorbed microwave power from 50 W to 400 W. For a discharge characterization we used the floating potentialU _fl and the saturated ion current densityi _sat ⁺ . The influence of the substrate holder presence on the plasma microparameters was studied. It was shown that for the substrate holder located near ECR at pressures below 0.3 Pa mainly the magnitude ofU _fl strongly depends on the pressurep, the absorbed microwave powerP _a, and the position of the substrate holder with respect to ECR. The values ofU _fl in the plasma in which the substrate holder is inserted strongly differ from those in the plasma without the substrate holder.U _fl of low pressuresp<0.05 Pa achieves high positive values of about +50 V and this results in sputtering of chamber walls.     

Productive Coreflective Classes in Top

If sequential cardinals do not exist then every topological space is generated from a converging sequence by using finite products, disjoint sums and quotients. The author acknowledges the support of the grants MSM 0021620839 and GAČR 201/06/0933 of Czech Republic.     

Uncertainty of chemical oxygen demand determination in wastewater samples

 The measurement uncertainty of the result of chemical oxygen demand determination in wastewater was evaluated. The major sources of uncertainty of the result of measurement were identified as the purity of reagents, volumetric operations, gravimetric operations, bias, and the repeatability of the method. Identification and evaluation of uncertainty sources was followed by combined uncertainty calculations. The combined uncertainty was compared to the experimentally determined variation and good agreement was found, indicating that the major uncertainty sources had been identified. The results show that the major sources of uncertainty arose from repeatability at high concentration level and volumetric steps at low concentration level, thus revealing the target operations for reducing the measurement uncertainty of this determination. Received: 5 August 2002 Accepted: 5 November 2002 Acknowledgements This research was supported by the Ministry of Education, Science and Sport of the Republic of Slovenia (Project Z2–3530). Presented at CERMM-3, Central European Reference Materials and Measurements Conference: The function of reference materials in the measurement process, May 30–June 1, 2002, Rogaška Slatina, Slovenia Correspondence to A. Drolc     

Effective Descent Morphisms in Some Quasivarieties of Algebraic, Relational, and More General Structures

We show that the class of effective descent morphisms coincides with the class of regular epimorphisms in suitable categories of internal structures in an exact category. In particular this applies to quasivarieties of (ordinary) first-order structures closed under strong homomorphic images.     

“Naturadeus”, a metaphor of the Perfect Diamond

In this essay, the author outlines his re-construction of Spinoza’s ontological monism by re-presenting the system of Ethica, ordine geometrico demonstrata, in an “intuitive” model of the Perfect Diamond, called NATURADEUS. So, for example, ordo et connexio idearum et rerum, is presented to the inner eye in the forms of two parallel structures, of rays and of facets within the NATURADEUS, respectively. The conceptual background of the proposed model is mostly analytic, the author essays to develop some ideas of Jonathan Bennett’s Spinoza’s metaphysics (especially “transattributive mode identity”), with strong emphasis on ethical issues of ontological monism or pantheism. This essay is written as a dialogue between master Bruno and his student John (physically absent at the moment). More philosophical dialogues of this kind can be found on the author’s web page and in his book Four Seasons (in Slovenian, 2002).     

Approximation of the Lerch Zeta-Function

We consider uniform in parameters approximations of the Lerch zeta-function by Dirichlet polynomials. It allows us to obtain uniform in parameters bounds in the critical strip.     

Cutting hyperplane arrangements

We consider a collectionH ofn hyperplanes in E ^d (where the dimensiond is fixed). An ε-cutting forH is a collection of (possibly unbounded)d-dimensional simplices with disjoint interors, which cover all E ^d and such that the interior of any simplex is intersected by at mostεn hyperplanes ofH. We give a deterministic algorithm for finding a (1/r)-cutting withO(r ^d ) simplices (which is asymptotically optimal). Forr≤n ^1−σ, where δ>0 is arbitrary but fixed, the running time of this algorithm isO(n(logn) ^O(1) r ^d−1). In the plane we achieve a time boundO(nr) forr≤n ^1−δ, which is optimal if we also want to compute the collection of lines intersecting each simplex of the cutting. This improves a result of Agarwal, and gives a conceptually simpler algorithm. For ann point setX⊆E ^d and a parameterr, we can deterministically compute a (1/r)-net of sizeO(rlogr) for the range space (X, {X ϒ R; R is a simplex}), In timeO(n(logn) ^O(1) r ^d−1 +r ^O(1)). The size of the (1/r)-net matches the best known existence result. By a simple transformation, this allows us to find ε-nets for other range spaces usually encountered in computational geometry. These results have numerous applications for derandomizing algorithms in computational geometry without affecting their running time significantly. A preliminary version of this paper appeared inProceedings of the Sixth ACM Symposium on Computational Geometry, Berkeley, 1990, pp. 1–9. Work on this paper was supported by DIMACS Center.     

Über die Elemisäure aus Manila-Elemiharz

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