Cooperative transport by small teams of molecular motors

Molecular motors power directed transport of cargoes within cells. Even if a single motor is sufficient to transport a cargo, motors often cooperate in small teams. We discuss the cooperative cargo transport by several motors theoretically and explore some of its properties. In particular we emphasize how motor teams can drag cargoes through a viscous environment.Comment: 9 pages, 1 figure, uses ws-brl.cls, presented at Bio-Systems conference, Berlin, June 200

The CoreGram Project: Theoretical Linguistics, Theory Development and Verification

This paper describes the CoreGram project, a multilingual grammar engineering project that develops HPSG grammars for several typologically diverse languages that share a common core. The paper provides a general motivation for doing theoretical linguistics the way it is done in the CoreGram project and therefore is not targeted at computational linguists exclusively. I argue for a constraint-based approach to language rather than a generative-enumerative one and discuss issues of formalization. Recent advantages in the language acquisition research are mentioned and conclusions on how theories should be constructed are drawn. The paper discusses some of the highlights in the implemented grammars, gives a brief overview of central theoretical concepts and their implementation in TRALE and compares the CoreGram project with other multilingual grammar engineering projects

Comparison of ion sites and diffusion paths in glasses obtained by molecular dynamics simulations and bond valence analysis

Based on molecular dynamics simulations of a lithium metasilicate glass we study the potential of bond valence sum calculations to identify sites and diffusion pathways of mobile Li ions in a glassy silicate network. We find that the bond valence method is not well suitable to locate the sites, but allows one to estimate the number of sites. Spatial regions of the glass determined as accessible for the Li ions by the bond valence method can capture up to 90% of the diffusion path. These regions however entail a significant fraction that does not belong to the diffusion path. Because of this low specificity, care must be taken to determine the diffusive motion of particles in amorphous systems based on the bond valence method. The best identification of the diffusion path is achieved by using a modified valence mismatch in the BV analysis that takes into account that a Li ion favors equal partial valences to the neighboring oxygen ions. Using this modified valence mismatch it is possible to replace hard geometric constraints formerly applied in the BV method. Further investigations are necessary to better understand the relation between the complex structure of the host network and the ionic diffusion paths.Comment: 16 pages, 10 figure

Soccer goes BOXing: synthetic access to novel [6:0] hexakis[(bisoxazolinyl)methano]fullerenes

The syntheses of [6:0] hexakis[(bisoxazolinyl)methano]fullerenes are presented. Two derivatives could be directly obtained using conditions developed by the Sun group. For the remaining products, a two stage protocol had to be developed. All compounds we obtained in synthetically useful scales and were purified via column chromatography with standard achiral phase. These new fullerene adducts bear six metal-chelation sites which are aligned in the three orthogonal space directions and are disposed on a completely rigid scaffold. First experiments indicate that the generation of six-fold metal-complexes is possible with these structures. This makes them very appealing as ligands in asymmetric catalysis and as building blocks in higher supra-molecular assemblies

An evaluation of user acceptance of a corporate intranet

Intranets represent an important organisational resource for knowledge sharing. However, as yet, there has been little research into the quality of intranets and the impact of quality on intranet user acceptance. In the study reported in this paper, an intranet quality assessment tool comprising the dimensions usability, design, and information quality, is combined with perceived usefulness and social influence from the technology acceptance literature to create an intranet acceptance model. The model is applied to the sales and marketing division of an international manufacturing company. Data is collected via a Web survey (n=131, response rate = 65.5%) and tested using the partial least squares approach to structural equation modelling. The results show that intranet quality is a significant factor in determining behavioural intention to use, although it is less important than perceived usefulness and social influence. Comments collected from respondents are used to illustrate the findings and provide an insight into user behaviour. The discussion considers the implications, future research (e.g., the role of social influence in intranet usage) and limitations. The paper rounds off with a short summary