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Search Results: 1 - 10 of 3426 matches for " Tobias "
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E-Commerce Business Models and Search Engine Dependency  [PDF]
Tobias Klatt
iBusiness (IB) , 2013, DOI: 10.4236/ib.2013.53B041
Abstract:

E-Commerce business models attracted a great deal of attention in the last years. An increasing number of bargains are realized via online transactions. However, some business models suffer distinctly under changes of search engine algorithms while others experience continuous stable traffic. This paper sheds light on the drivers of the unpunished e-commerce businesses based on a case-by-case analysis of 43 business models in the German Internet market. The analysis reveals that more stable business models are characterized by diversified customer arrivals which are obtained by a focused product management, multiple marketing channeling, freemium registration strategies and a subtle way to attract customer trust.

The Generalized wH Value  [PDF]
Tobias Hiller
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.43034
Abstract:

In this note, we generalize the wHSh value [1] [2] for CO values.

How Safe Is Conversion from Tacrolimus to Its Generic Drug?—A Single Center Experience  [PDF]
Tobias A. Marsen
Open Journal of Nephrology (OJNeph) , 2012, DOI: 10.4236/ojneph.2012.24012
Abstract: Background: Generically produced cyclosporine has long been approved in the treatment of organ transplant recipients and several publications have dealt with its use. For tacrolimus, however, very few data exist for safety and efficacy after conversion to its generic in kidney transplant recipients. Methods: In this single-center observational study, 14 kidney transplant carriers were converted to generic tacrolimus as part of aftercare, and graft function, fasting tacrolimus levels and the daily tacrolimus dose was pursued for up to 95 weeks. Results: Average drug doses changed from 3.64 ± 1.88 mg/day with the original to 3.33 ± 1.72 mg/day after conversion to generic tacrolimus (p = 0.33). Tacrolimus fasting levels were 6.23 ± 1.68 ng/ml before and 5.89 ± 1.15 ng/ml after conversion (p = 0.66). Average serum creatinine values of 2.26 ± 1.08 mg/dl after conversion did not differ from previous values of 1.99 ± 0.74 mg/dl (p = 0.15). Conclusions: These data support the assumption, that it is safe to convert stable kidney transplant patients from the original galenic formulation under close scrutiny to the generically produced substance. Conversion is easy to be implemented in the routine follow-up and thus represents an option in the therapy with calcineurin inhibitors, which will contribute to cost reduction in the health system.
Herbicidal Effects of Fungicides on Arable Weeds  [PDF]
Henning Nordmeyer, Tobias Koch
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.51006
Abstract:

In the present study, the herbicidal effects of two fungicides with the active ingredients expoxiconazole, fluxapyroxad, pyraclostrobin and fenpropimorph on the two arable weeds Lamium purpureum L. and Chenopodium album L. were investigated. The experiments were conducted in a climate chamber under defined conditions. Sowing pods were prepared and plants at the cotyledon leaf stage were pricked out in test pods. Fungicides were applied at six application rates: 0%, 12.5%, 25%, 50%, 100% and 200% of the maximum registered dose rate in Germany. Seven days after application, the first assessment was conducted, regarding growth stage, quantity of plants and visible plant damage. Fourteen days after application, the second and final assessment was conducted, regarding growth stage, quantity of plants, visible plant damage and the fresh weight of the plants. There were herbicidal effects of the fungicides, which were presumably due to the active ingredient epoxiconazole. Epoxiconazole has effects on enzymes that are dependent on cytochrome P-450 and inhibits sterol biosynthesis and probably gibberellin synthesis. By doing so, these fungicides have similar effects to plant growth regulators. Weed species showed differential sensitivities, contractions and growth inhibition and ED50-values were calculated. Notwithstanding the probably minor relevance of the present results in agricultural practice, some effects on arable weeds might result if fungicides are applied at an early growth stage in the field. In some cases, the crop-weed competition could be shifted to the benefit of the crop. Nevertheless, the results are interesting for the field of weed research and for the assessment of the ecotoxicology of fungicides.

Multi-Criteria Decision Analysis for Usage Based Optimization of Powertrains  [PDF]
Tobias Hellberg, Martin Meywerk
Engineering (ENG) , 2016, DOI: 10.4236/eng.2016.86029
Abstract: The electrification of powertrains leads to an increasing diversification of powertrain configurations. Each single configuration has its specific advantages which appear depending on the usage profile. To find the usage based optimal powertrain in consideration of a variety of evaluation criteria, the powertrains have to be optimized for the usage profile and characteristics have to be extracted from the usage profile. The carbon dioxide emissions of the optimized powertrains and usage based criteria are used in a multi-criteria decision analysis to determine the optimal powertrain for a specific usage profile. The description of characteristic maps forms the objective function of a minimization problem. The determined carbon dioxide emissions are one criterion in a multi-criteria decision process. All considered criteria are at least partly objective so that subjective ratings are eliminated as far as possible. The result is an optimized powertrain for a desired usage under the consideration of objective criteria that are extracted from the usage profile.
Gaussian approximations for stochastic systems with delay: chemical Langevin equation and application to a Brusselator system
Tobias Brett,Tobias Galla
Physics , 2013, DOI: 10.1063/1.4867786
Abstract: We present a heuristic derivation of Gaussian approximations for stochastic chemical reaction systems with distributed delay. In particular we derive the corresponding chemical Langevin equation. Due to the non-Markovian character of the underlying dynamics these equations are integro-differential equations, and the noise in the Gaussian approximation is coloured. Following on from the chemical Langevin equation a further reduction leads to the linear-noise approximation. We apply the formalism to a delay variant of the celebrated Brusselator model, and show how it can be used to characterise noise-driven quasi-cycles, as well as noise-triggered spiking. We find surprisingly intricate dependence of the typical frequency of quasi-cycles on the delay period.
Generating functionals and Gaussian approximations for interruptible delay reactions
Tobias Brett,Tobias Galla
Physics , 2015, DOI: 10.1103/PhysRevE.92.042105
Abstract: We develop a generating functional description of the dynamics of non-Markovian individual-based systems, in which delay reactions can be terminated before completion. This generalises previous work in which a path-integral approach was applied to dynamics in which delay reactions complete with certainty. We construct a more widely applicable theory, and from it we derive Gaussian approximations of the dynamics, valid in the limit of large, but finite population sizes. As an application of our theory we study predator-prey models with delay dynamics due to gestation or lag periods to reach the reproductive age. In particular we focus on the effects of delay on noise-induced cycles.
Cross ratios, translation lengths and maximal representations
Tobias Hartnick,Tobias Strubel
Mathematics , 2009,
Abstract: We define a family of four-point invariants for Shilov boundaries of bounded symmetric domains of tube type, which generalizes the classical four-point cross ratio on the unit circle. This generalization, which is based on a similar construction of Clerc and {\O}rsted, is functorial and well-behaved under products; these two properties determine our extension uniquely. Our generalized cross ratios can be used to estimate translation lengths of a large class of isometries of the underlying bounded symmetric domain. Our main application concerns maximal representations of surface groups with Hermitian target. For any such representation we can construct a strict cross ratio on the circle in the sense of Labourie via pullback of our generalized cross ratio along a suitable limit curve. In this context our translation length estimates then imply that maximal representations with Hermitian target are well-displacing; this implies in particular that the action of the mapping class group on the moduli space of maximal representations into a Hermitian Lie group is proper.
Stochastic processes with distributed delays: chemical Langevin equation and linear-noise approximation
Tobias Brett,Tobias Galla
Quantitative Biology , 2013, DOI: 10.1103/PhysRevLett.110.250601
Abstract: We develop a systematic approach to the linear-noise approximation for stochastic reaction systems with distributed delays. Unlike most existing work our formalism does not rely on a master equation, instead it is based upon a dynamical generating functional describing the probability measure over all possible paths of the dynamics. We derive general expressions for the chemical Langevin equation for a broad class of non-Markovian systems with distributed delay. Exemplars of a model of gene regulation with delayed auto-inhibition and a model of epidemic spread with delayed recovery provide evidence of the applicability of our results.
Correlation between Chemical Glass Components and the Glass Sticking on Sputtered PtIr Physical Vapour Deposition Coatings for Precision Blank Moulding  [PDF]
Kirsten Bobzin, Nazlim Bagcivan, Tobias Br?gelmann, Tobias Münstermann
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.55037
Abstract:

The increasing demand on high quality optical systems with complex geometries, low tolerances and a low installation space necessitates new replicative production systems for complex optical glass elements. The technology precision blank moulding shows promising properties to comply with these demands on an industrial bulk production. Due to the required high surface quality and low surface roughness of produced optical elements, moulding dies must have comparable low roughness and defect-free surfaces. To reduce wear and chemical interaction with the hot glass, moulding dies are often coated with a thin sputtered physical vapour deposition (PVD) coating. The objective of this research work was to analyze the diffusion behaviour inside different industrially used low-Tg (transformation point) glasses and their interaction with three different noble metal coating systems during an application oriented heating test. Therefore, three different PtIr coating systems with different interlayers (50 nm nickel as reference, 20 nm chromium, without interlayer) were deposited and tested in combination with six different industrially used low-Tg glasses. Using energy-dispersive X-ray spectroscopy (EDS) a diffusion of the light alkali and alkaline earth metals (sodium, potassium, calcium) was detected. The interaction between glass and coating was analyzed by EDS, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The different chemical compositions of the glasses have a significant influence on the interaction between glass and coating system. Several correlations between the chemical composition of the glasses and the amount of glass adhesion on the three coating systems were identified. The percentage of ions allocated to network modifiers lithium oxide, sodium oxide and potassium oxide correlates with the intensity of the interaction between coating and glass. The intensity of glass adhesion on the reference coating system PtIr/Ni is related with the zinc content in the glasses. Due to a diffusion process of the nickel interlayer, a direct correlation between the zinc content in the glasses and glass adhesion exists. The coating system with chromium interlayer showed comparable results to the system without interlayer.

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