Suppression of thermally activated escape by heating

The problem of thermally activated escape over a potential barrier is solved by means of path integrals for one-dimensional reaction dynamics with very general time dependences. For a suitably chosen but still quite simple static potential landscape, the net escape rate may be substantially reduced by temporally increasing the temperature above its unperturbed constant level.Comment: 4 pages, 2 figure

Optimal evaluation of single-molecule force spectroscopy experiments

The forced rupture of single chemical bonds under external load is addressed. A general framework is put forward to optimally utilize the experimentally observed rupture force data for estimating the parameters of a theoretical model. As an application we explore to what extent a distinction between several recently proposed models is feasible on the basis of realistic experimental data sets.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev.

Physical Modelling of a Light Rail HVAC System Using Long-Term Measurements

A method to develop a physical HVAC model of a light rail using only operation data from long-term measurements is presented. Physical HVAC modelling is often based on costly wind tunnel tests or time and computationally intensive CFD calculations. This method is a new approach using only data from everyday operation of the light rail, reducing modelling cost and improving the model accuracy since real life conditions are analysed. Data from two years of passenger operation of a suburban light rail in Karlsruhe, Germany, is used. A standard physical model for a HVAC system and a train compartment is developed. This model is parametrised using data driven modelling and model training. For data driven modelling, the conducted data is analysed and suitable models are derived. For example, the cooling system is modelled using a look-up table based approach developed with the data. For model training, the data is first separated into test and training data. The training data is then separated into different batches (heating up, winter-night, winter-day and summer), to parameterise different physical quantities of the model. Using a systematic grid search, parameters that fit the training data in an optimal manner are found. Finally, the overall model is validated using the test data. Over a large temperature range from -5 °C to 35 °C the model shows good consistency with the test data. The mean absolute percentage error over all test data is 13 %. Within the batches, the summer data was modelled best with an error of about 8 %. The described method allows a fast and reliable method to develop an accurate physical HVAC model

The influence of time and money on product evaluations: A neurophysiological analysis

"Time is money" is how a common saying goes, reflecting a widespread assumption in many people\u27s everyday life. It seems that money and time are very similar concepts which might even be exchangeable all together. However, the neurophysiological processes underlying the activation of time or money are not yet completely understood. In order to understand in how far and in which dimensions the concept of time versus the concept of money effects human behavior we enquired the neural differences of the time versus money effect. This paper broadens the understanding of both concepts and investigates the posited distinct mindsets of time and money using functional magnetic resonance imaging (fMRI) technology. A sample of 44 righthanded adults has been analyzed. Our data supports the idea of the existence of two distinct mindsets for time and money. However, contrasting both conditions in one general linear model only a few significant differences have been found. The insula seems to be a crucial locus for the neural difference of both mindsets. Higher insula activation in the time condition suggests stronger urge for the product primed with time

Multiphysics Simulation of a Battery Electric Train Operation

The changeover from diesel driven multiple units to battery electric multiple units is a challenge for operators due to the limited range of these trains. Therefore, in this paper a tool is developed and described that simulates the entire operation of a battery electric train. The tool contains a model of the track, the vehicle, the timetable and the environment. The model of the track is built on elevation profiles, radius information and speed limitation. The vehicle model is derived from an electric multiple unit suitable for local and commuter train operation. To do parametric studies or model different train units it is easily possible to change vehicle properties. Modeling the timetable and the environment allows the simulation of an entire operation day. The overall simulation model was validated and is consistent. Finally examples show the simulation possibilities and features of the tool

On the Lubensky-Nelson model of polymer translocation through nanopores

We revisit the one-dimensional stochastic model of Lubensky and Nelson [Biophys. J 77, 1824 (1999)] for the electrically driven translocation of polynucleotides through alpha-hemolysin pores. We show that the model correctly describes two further important properties of the experimentally observed translocation time distributions, namely their spread (width) and their exponential decay. The resulting overall agreement between theoretical and experimental translocation time distributions is thus very good

Enabling Cysteine-Free Native Chemical Ligation at Challenging Junctions with a Ligation Auxiliary Capable of Base Catalysis

Ligation auxiliaries are used in chemical protein synthesis to extend the scope of native chemical ligation (NCL) beyond cysteine. However, auxiliary-mediated ligations at sterically demanding junctions have been difficult. Often the thioester intermediate formed in the thiol exchange step of NCL accumulates because the subsequent S→N acyl transfer is extremely slow. Here we introduce the 2-mercapto-2-(pyridin-2-yl)ethyl (MPyE) group as the first auxiliary designed to aid the ligation reaction by catalysis. Notably, the MPyE auxiliary provides useful rates even for junctions containing proline or a β-branched amino acid. Quantum chemical calculations suggest that the pyridine nitrogen acts as an intramolecular base in a rate-determining proton transfer step. The auxiliary is prepared in two steps and conveniently introduced by reductive alkylation. Auxiliary cleavage is induced upon treatment with TCEP/morpholine in presence of a MnII complex as radical starter. The synthesis of a de novo designed 99mer peptide and an 80 aa long MUC1 peptide demonstrates the usefulness of the MPyE auxiliary.Peer Reviewe