Quantum phase transitions in magnetic systems: application of coupled cluster method

Magdeburg, Univ., Fak. für Naturwiss., Diss., 2009

integrated method for improving risk analysis using human factors methods and virtual reality

Magdeburg, Univ., Fak. für Informatik, Diss., 2009

Advanced production systems : developing context-oriented method and adaptation capabilities for enhanced supply network

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2014

Line-fitting method of model order reduction for elastic multibody systems

Magdeburg, Univ., Fak. für Maschinenbau, Diss., 2015

Development of a new method for the characterisation of bioreactors concerning heat and mass transfer

Since the specific heat transfer coefficient (UA) and the volumetric mass transfer coefficient (kLa) play an important role for the design of biotechnological processes, different techniques were developed in the past for the determination of these parameters. However, these approaches often use imprecise dynamic methods for the description of stationary processes and are limited towards scale and geometry of the bioreactor. Therefore, the aim of this thesis was to develop a new method, which overcomes these restrictions. This new approach is based on a permanent production of heat and oxygen by the constant decomposition of hydrogen peroxide in continuous mode. Since the degradation of H2O2 at standard conditions only takes place by the support of a catalyst, different candidates were investigated for their potential (regarding safety issues and reaction kinetic). Manganese-(IV)-oxide was found to be suitable. To compensate the inactivation of MnO2, a continuous process with repeated feeds of fresh MnO2 was established. Subsequently, a scale-up was successfully carried out from 100 mL to a 5 litre glass bioreactor (UniVessel®)To show the applicability of this new method for the characterisation of bioreactors, it was compared with common approaches. With the newly established technique as well as with a conventional procedure, which is based on an electrical heat source, specific heat transfer coefficients were measured in the range of 17.1 – 24.8 W/K for power inputs of about 50 – 70 W/L. However, a first proof of concept regarding the mass transfer showed no constant kLa for different dilution rates up to 0.04 h-1.Based on this, consecutive studies concerning the mass transfer should be made with higher volume flows, due to more even inflow rates. In addition, further experiments are advisable, to analyse the heat transfer in single-use bioreactors and in larger common systems.

The differentiation of character state relationships by binary coding and the monothetic subset method / Hymen Marx, George B. Rabb and Harold K. Voris.

v.72:no.1(1977)

On the upper bound of the number of limit cycles obtained by the second order averaging method I

"Vegeu el resum a l'inici del document del fitxer adjunt."

On the upper bound of the number of limit cycles obtained by the second order averaging method II

"Vegeu el resum a l'inici del document del fitxer adjunt."

A rotation method which gives linear Lp-Estimates for powers of the Ahlfors-Beurling operator

"Vegeu el resum a l'inici del document del fitxer adjunt."

Stability of periodic solutions obtained via the averaging method for nonsmooth Lipschitz system

"Vegeu el resum a l'inici del document del fitxer adjunt."

The Determinants of pricing in pharmaceuticals: are U.S. prices really higher than those of Canada?

This paper studies price determination in pharmaceutical markets using data for 25 countries, six years and a comprehensive list of products from the MIDAS IMS database. We show that market power and the quality of the product has a significantly positive impact of prices. The nationality of the producer appears to have a small and often insignificant impact on prices, which suggests that countries which regulates prices have relatively little power to do it in a way that advances narrow national interest. We produce a theoretical explanation for this phenomenon based on the fact that low negotiated prices in a country would have a knock-on effect in other markets, and is thus strongly resisted by producers. Another key finding is that the U.S. has prices that are not significantly higher than those of countries with similar income levels. This, together with the former observation on the effect of the nationality of producers casts doubt on the ability of countries to purs

Quantitative method of viral pollution determination for large volume of water using ferric hydroxide gel impregnated on the surface of glassfibre cartridge

Quantitative method of viral pollution determination for large volume of water using ferric hydroxide gel impregnated on the surface of glassfibre cartridge filter. The use of ferric hydroxide gel, impregnated on the surface of glassfibre cartridge filter enable us to recover 62.5% of virus (Poliomylitis type I, Lsc strain) exsogeneously added to 400 liters of tap-water. The virus concentrator system consists of four cartridge filters, in which the three first one are clarifiers, where the contaminants are removed physically, without significant virus loss at this stage. The last cartridge filter is impregnated with ferric hydroxide gel, where the virus is adsorbed. After the required volume of water has been processed, the last filter is removed from the system and the viruses are recovered from the gel, using 1 liter of glycine/NaOH buffer, at pH 11. Immediately the eluate is clarified through series of cellulose acetate membranes mounted in a 142mm Millipore filter. For the second step of virus concentration, HC1 1N is added slowly to the eluate to achieve pH 3.5-4. MgC1, is added to give a final concentration of 0.05M and the viruses are readsorbed on a 0.45 , porosity (HA) cellulose acetate membrane, mounted in a 90 mm Millipore filter. The viruses are recovered using the same eluent plus 10% of fetal calf serum, to a final volume of 3 ml. In this way, it was possible to concentrate virus from 400 liters of tap-water, into 1 liter in the first stage of virus concentration and just to 3 ml of final volume in a second step. The efficiency, simplicity and low operational cost, provded by the method, make it feasible to study viral pollution of recreational and tap-water sources.

A Retail benchmarking approach to eficient two-way access pricing

We study a retail benchmarking approach to determine access prices for interconnected networks. Instead of considering fixed access charges as in the existing literature, we study access pricing rules that determine the access price that network i pays to network j as a linear function of the marginal costs and the retail prices set by both networks. In the case of competition in linear prices, we show that there is a unique linear rule that implements the Ramsey outcome as the unique equilibrium, independently of the underlying demand conditions. In the case of competition in two-part tariffs, we consider a class of access pricing rules, similar to the optimal one under linear prices but based on average retail prices. We show that firms choose the variable price equal to the marginal cost under this class of rules. Therefore, the regulator (or the competition authority) can choose one among the rules to pursue additional objectives such as consumer surplus, network covera.

A simple method to purify biologically and antigenically preserved bloodstream trypomastigotes of Trypanosoma cruzi using Deae-cellulose columns

A method to purify trypanosomastigotes of some strains of Trypanosoma cruzi (Y, CL, FL, F, "Berenice", "Colombiana" and "São Felipe") from mouse blood by using DEAE-cellulose columns was standardized. This procedure is a modification of the Lanham & Godfrey methods and differs in some aspects from others described to purify T. cruzi bloodstream trypomastigotes, mainly by avoidance of prior purifications of parasites. By this method, the broad trypomastigotes were mainly isolated, accounting for higher recoveries obtained with strains having higher percentages of these forms: processing of infected blood from irradiated mice could be advantageous by increasing the recovery of parasites (percentage and/or total number) and elution of more slender trypomastigotes. Trypomastigotes purified by this method presented normal morphology and motility, remained infective to triatomine bugs and mice, showing in the latter prepatent periods and courses parasitemia similar to those of control parasites, and also reproducing the polymorphism pattern of each strain. Their virulence and pathogenicity also remained considerably preserved, the latter property being evaluated by LD 50 tests, mortality rates and mean survival time of inoculated mice. Moreover, these parasites presented positive, clear and peripheral immunofluorescence reaction at titres similar to those of control organisms, thus suggesting important preservation of their surface antigens.