Characterizing Potentials by a Generalized Boltzmann Factor

Based on the concept of a nonequilibrium steady state, we present a novel method to experimentally determine energy landscapes acting on colloidal systems. By measuring the stationary probability distribution and the current in the system, we explore potential landscapes with barriers up to several hundred \kT. As an illustration, we use this approach to measure the effective diffusion coefficient of a colloidal particle moving in a tilted potential

Electronic transport properties through thiophenes on switchable domains

The electronic transport of electrons and holes through stacks of $\alpha$,\ome ga-dicyano-$\beta$,$\beta$'-dibutyl- quaterthiophene (DCNDBQT) as part of a nov el organic ferroic field-effect transistor (OFFET) is investigated. The novel ap plication of a ferroelectric instead of a dielectric substrate provides the poss ibility to switch bit-wise the ferroelectric domains and to employ the polarizat ion of these domains as a gate field in an organic semiconductor. A device conta ining very thin DCNDBQT films of around 20 nm thickness is intended to be suitab le for logical as well as optical applications. We investigate the device proper ties with the help of a phenomenological model called multilayer organic light-e mitting diodes (MOLED), which was extended to transverse fields. The results sho wed, that space charge and image charge effects play a crucial role in these org anic devices

Wrinkling of microcapsules in shear flow

Elastic capsules can exhibit short wavelength wrinkling in external shear flow. We analyse this instability of the capsule shape and use the length scale separation between the capsule radius and the wrinkling wavelength to derive analytical results both for the threshold value of the shear rate and for the critical wave-length of the wrinkling. These results can be used to deduce elastic parameters from experiments.Comment: 4 pages, 2 figures, submitted to PR

Noninvasive Measurement of Dissipation in Colloidal Systems

According to Harada and Sasa [Phys. Rev. Lett. 95, 130602 (2005)], heat production generated in a non-equilibrium steady state can be inferred from measuring response and correlation functions. In many colloidal systems, however, it is a nontrivial task to determine response functions, whereas details about spatial steady state trajectories are easily accessible. Using a simple conditional averaging procedure, we show how this fact can be exploited to reliably evaluate average heat production. We test this method using Brownian dynamics simulations, and apply it to experimental data of an interacting driven colloidal system

Tidal controls on trace gas dynamics in a seagrass meadow of the Ria Formosa lagoon (southern Portugal)

Coastal zones are important source regions for a variety of trace gases, including halocarbons and sulfur-bearing species. While salt marshes, macroalgae and phyto-plankton communities have been intensively studied, little is known about trace gas fluxes in seagrass meadows. Here we report results of a newly developed dynamic flux chamber system that can be deployed in intertidal areas over full tidal cycles allowing for highly time-resolved measurements. The fluxes of CO2, methane (CH4) and a range of volatile organic compounds (VOCs) showed a complex dynamic mediated by tide and light. In contrast to most previous studies, our data indicate significantly enhanced fluxes during tidal immersion relative to periods of air exposure. Short emission peaks occurred with onset of the feeder current at the sampling site. We suggest an overall strong effect of advective transport processes to explain the elevated fluxes during tidal immersion. Many emission estimates from tidally influenced coastal areas still rely on measurements carried out during low tide only. Hence, our results may have significant implications for budgeting trace gases in coastal areas. This dynamic flux chamber system provides intensive time series data of community respiration (at night) and net community production (during the day) of shallow coastal systems.German Federal Ministry of Education and Research (BMBF) [03F0611E, 03F0662E]; EU FP7 ASSEMBLE research infrastructure initiative

Thermodynamics of a Colloidal Particle in a Time-Dependent Non-Harmonic Potential

We study the motion of an overdamped colloidal particle in a time-dependent non-harmonic potential. We demonstrate the first law-like balance between applied work, exchanged heat, and internal energy on the level of a single trajectory. The observed distribution of applied work is distinctly non-Gaussian in good agreement with numerical calculations. Both the Jarzynski relation and a detailed fluctuation theorem are verified with good accuracy

The Einstein relation generalized to non-equilibrium

The Einstein relation connecting the diffusion constant and the mobility is violated beyond the linear response regime. For a colloidal particle driven along a periodic potential imposed by laser traps, we test the recent theoretical generalization of the Einstein relation to the non-equilibrium regime which involves an integral over measurable velocity correlation functions

Injuries to the Stomatognathic System in Tae-Kwon-Do

Martial arts are high-risk sports for injuries to the stomatognathic system, according to the FDI classification. The aim of this investigation was to determine frequency, type and severity of injuries to the stomatognathic system, during Tae-Kwon-Do, and the use of protection devices during training and competitions. This investigation included 43 examinees, 15 female and 28 male, among which were members of the national representatives of the Republic of Croatia. They were required to complete a questionnaire. The result revealed a very low number of injuries, in fact, lack of injuries in the female and male junior categories. In the male junior and both senior categories 134 injuries were reported, 118 or 88% of them were laceration of the lips, cheeks and tongue. Other injuries to the stomatognathic system represent only 16 injuries or 12% of all injuries. The majority of injuries occurred during training (68%), and 32% during competition. Protection devices (helmets) were used during training only by 5 examinees (11.63%), and during competition (100%). Mouthguards of any type were not used by any examinee. Helmets used are obligatory during competition and prevent the occurrence of injuries to the stomatognathic system, and decrease the severity of injury