Computational statistics for cell survival curves. II. Evaluation of colony-forming ability of a group of cell strains by the APL function CFAGROUP

An interactive program for the statistical analysis of groups of cell survival curves is described. Methods from linear regression are applied in the presence of repeated experiments and estimates of a common slope and its variance are obtained by weighted means and a bootstrap resampling technique.     

Morphological Forms of Tobermorite in Hydrothermally Treated Calcium Silicate Hydrate Gels

The morphology of the calcium silicate hydrate phase, tobermorite, generally thought to be the bonding phase in ordinary portland cement, was studied. Tobermorite was hydrothermally synthesized at pH 12.6 at 150°C. The powder was characterized by XRD and SEM analysis. Modeling of the morphology was performed using the SHAPE and ATOMS programs. Two morphologies were produced: fibers and platelets. Computer calculations of equilibrium particle shape suggest that growth occurs on the (110)-type planes for both morphologies.     

Catalytic splitting of acetals to unsaturated ethers

Catalytic splitting of the dimethylacetals of heptanal, 3-cyclohexylpropanal, 3-cyclohexylbutanal, 3-phenylpropanal and 3-phenylbutanal to corresponding unsaturated ethers was studied in a gas phase. Acid catalysts were employed in the study. Reaction conditions favorable to high splitting selectivity to ethers were suggested. The original acetals as well as synthesized unsaturated methylethers revealed characteristic odoring properties.     

Mobile communities: How viable are their business models? An exemplary investigation of the leisure industry

Communities (especially Virtual Communities) of Interest have been the focus of substantial discussion in academic literature. This paper addresses Communities of Interest within the leisure industry and discusses possible business models for the parties operating the platform. The described community platform is an innovative value added service concept for a mobile coordination support for individuals—A Mobile Community Support System. In this paper we extend the discussion about mobile communities to hybrid communities. The communities are hybrid in two ways: they use two different access channels, the Web and mobile devices, and they are built on real-world leisure communities that constitute themselves in the form of buddy lists in the virtual world of an ICT supported platform. We briefly depict the state of the art of IT in the leisure industry and describe the empirical aspects of the project objectives of the MCOR (Mobile Community Online Reservation) system. We conclude with some final remarks about design considerations and a blueprint for future research. Felix Hampe holds a chair for Corporate Communication Systems and is Director of the Institute for IS Research at the Faculty of Informatics of the University of Koblenz-Landau in Germany. He studied at the Free University of Berlin and worked later for the University of Bielefeld and the Philipps-University of Marburg prior to his appointment to Koblenz. In 2004/2005, he spent one year as a visiting professor at the University of South Australia, School of Computer and Information Systems. Beside his research interest in application aspects of communication systems, Professor Hampe started very early research in the area of mobile applications and especially mobile commerce. He was cofounder and board member of the Mobile Application Research Center (MARC), a German network for joint research on mobile business. Professor Hampe authored several international conference articles in the area and served for many international conferences.     

Mapping sediment-laden sea ice in the Arctic using AVHRR remote-sensing data: Atmospheric correction and determination of reflectances as a function of ice type and sediment load

Exploiting the fact that the spectral characteristics of light backscattered from sediment-laden ice differ substantially from those of clean ice and that sediment tends to accumulate at the ice surface during the first melt season, remote-sensing techniques provide a valuable tool for mapping the extent of particle-laden ice in the Arctic basin and assessing its particulate loading. This study considers two fundamental problems that still need to be addressed in order to make full use of satellite observations for this type of assessment: (i) the effects of the atmosphere on surface reflectances derived from radiances measured by the satellite sensor need to be quantified and ultimately corrected for, and (ii) the spectral reflectance of the ice surface as a function of particle loading and sub-pixel distribution needs to be determined in order to derive quantitative estimates from the at-sensor satellite signal. Here, spectral albedos have been computed for different ice surfaces of variable sediment load with a radiative transfer model for sea ice coupled with an optical model for particulates included in sea ice. In a second step, the role of the atmosphere in modulating the surface reflectance signal is assessed with the aid of an atmospheric radiative transfer model applied to a “standard” Arctic atmosphere and surface boundary conditions as prescribed by the sea ice radiative transfer model. A series of sensitivity studies helps assess differences between top-of-the-atmosphere and true surface reflectance and has been utilized to derive a look-up table for atmospheric correction of Advanced Very High Resolution Radiometer (AVHRR) data over sediment-laden sea ice surfaces. In particular, the effects of solar elevation, viewing geometry, and atmospheric properties are considered. The atmospheric corrections are necessary for certain geometries and surface types. Large discrepancies between raw and corrected data are particularly evident in the derived coverage of clean ice and ice with small sediment loading.     

An Advanced ‘clickECM’ That Can be Modified by the Inverse-Electron-Demand Diels-Alder Reaction

The extracellular matrix (ECM) represents the natural environment of cells in tissue and therefore is a promising biomaterial in a variety of applications. Depending on the purpose, it is necessary to equip the ECM with specific addressable functional groups for further modification with bioactive molecules, for controllable cross-linking and/or covalent binding to surfaces. Metabolic glycoengineering (MGE) enables the specific modification of the ECM with such functional groups without affecting the native structure of the ECM. In a previous approach (S. M. Ruff, S. Keller, D. E. Wieland, V. Wittmann, G. E. M. Tovar, M. Bach, P. J. Kluger, Acta Biomater. 2017 , 52, 159–170), we demonstrated the modification of an ECM with azido groups, which can be addressed by bioorthogonal copper-catalyzed azide-alkyne cycloaddition (CuAAC). Here, we demonstrate the modification of an ECM with dienophiles (terminal alkenes, cyclopropene), which can be addressed by an inverse-electron-demand Diels-Alder (IEDDA) reaction. This reaction is cell friendly as there are no cytotoxic catalysts needed. We show the equipment of the ECM with a bioactive molecule (enzyme) and prove that the functional groups do not influence cellular behavior. Thus, this new material has great potential for use as a biomaterial, which can be individually modified in a wide range of applications.     

Identifying material parameters in crystal plasticity by Bayesian optimization

Optimization and Engineering - In this work, we advocate using Bayesian techniques for inversely identifying material parameters for multiscale crystal plasticity models. Multiscale approaches for...