On the relation of protein dynamics and exciton relaxation in pigment–protein complexes: An estimation of the spectral density and a theory for the calculation of optical spectra

A theory for calculating time– and frequency–domain optical spectra of pigment–protein complexes is presented using a density matrix approach. Non-Markovian effects in the exciton–vibrational coupling are included. A correlation function is deduced from the simulation of 1.6 K fluorescence line narrowing spectra of a monomer pigment–protein complex (B777), and then used to calculate fluorescence line narrowing spectra of a dimer complex (B820). A vibrational sideband of an excitonic transition is obtained, a distinct non-Markovian feature, and agrees well with experiment on B820 complexes. The theory and the above correlation function are used elsewhere to make predictions and compare with data on time–domain pump–probe spectra and frequency–domain linear absorption, circular dichroism and fluorescence spectra of Photosystem II reaction centers

Measurements of Penetration and Detoxification of PS II Herbicides in Whole Leaves by a Fluorometric Method

The effect of herbicides that inhibit the photosynthetic electron transport at the photosystem II acceptor side has been analyzed in whole plants by using a fluorometric method. The data reported indicate that the apparent variable fluorescence of the induction curve normalized to the control value provides reliable information about the penetration rate and metabolic detoxification of PS II herbicides in whole plants

Sustainability of the Slovenian Pension System: An Analysis with an Overlapping-generations General Equilibrium Model

The article presents an analysis of welfare effects in Slovenia, an analysis of macroeconomic effects of the Slovenian pension reform and an analysis of effects of the pension fund deficit on sustainability of Slovenian public finances with a dynamic OLG general equilibrium model. It has been established that while young generations and new generations will lose from the pension reform, even complete implementation of the reform might not be sufficient to compensate unfavourable demographic developments. The level of expected deficit of the PAYG-financed state pension fund seems to be most worrying. Financing the pension system with VAT revenues as an extreme case could result in more sustainable public finances, since GDP and welfare levels ought to increase, yet this might be infeasible to implement politically, given that the generations of voters would have their welfare decreased. In addition, the present pension system is intransparent and tremendously complicated and should primarily be made more comprehensible to the public.general equilibrium models, macroeconomic effects, OLG-GE, PAYG, pension system, sustainability of public finances, Slovenia, welfare analysis

On microscopic origins of generalized gradient structures

Classical gradient systems have a linear relation between rates and driving forces. In generalized gradient systems we allow for arbitrary relations derived from general non-quadratic dissipation potentials. This paper describes two natural origins for these structures. A first microscopic origin of generalized gradient structures is given by the theory of large-deviation principles. While Markovian diffusion processes lead to classical gradient structures, Poissonian jump processes give rise to cosh-type dissipation potentials. A second origin arises via a new form of convergence, that we call EDP-convergence. Even when starting with classical gradient systems, where the dissipation potential is a quadratic functional of the rate, we may obtain a generalized gradient system in the evolutionary $\Gamma$-limit. As examples we treat (i) the limit of a diffusion equation having a thin layer of low diffusivity, which leads to a membrane model, and (ii) the limit of diffusion over a high barrier, which gives a reaction-diffusion system.Comment: Keywords: Generalized gradient structure, gradient system, evolutionary \Gamma-convergence, energy-dissipation principle, variational evolution, relative entropy, large-deviation principl

From large deviations to semidistances of transport and mixing: coherence analysis for finite Lagrangian data

One way to analyze complicated non-autonomous flows is through trying to understand their transport behavior. In a quantitative, set-oriented approach to transport and mixing, finite time coherent sets play an important role. These are time-parametrized families of sets with unlikely transport to and from their surroundings under small or vanishing random perturbations of the dynamics. Here we propose, as a measure of transport and mixing for purely advective (i.e., deterministic) flows, (semi)distances that arise under vanishing perturbations in the sense of large deviations. Analogously, for given finite Lagrangian trajectory data we derive a discrete-time and space semidistance that comes from the "best" approximation of the randomly perturbed process conditioned on this limited information of the deterministic flow. It can be computed as shortest path in a graph with time-dependent weights. Furthermore, we argue that coherent sets are regions of maximal farness in terms of transport and mixing, hence they occur as extremal regions on a spanning structure of the state space under this semidistance---in fact, under any distance measure arising from the physical notion of transport. Based on this notion we develop a tool to analyze the state space (or the finite trajectory data at hand) and identify coherent regions. We validate our approach on idealized prototypical examples and well-studied standard cases.Comment: J Nonlinear Sci, 201

The DLR Complex Irradiation Facility (CIF)

The DLR Institute of Space Systems in Bremen has built a new facility to study the behavior of materials under complex irradiation and to estimate their degradation in a space environment. It is named Complex Irradiation Facility (CIF). CIF allows simultaneously irradiating samples with three light sources for the simulation of the spectrum of solar electromagnetic radiation. The light sources are a solar simulator with a Xe-lamp (wavelength range 300-1200nm), a deuterium-UV-source (112-200nm), and an Argon-gas-jet-VUV-simulator. The latter allows irradiating samples with shorter wavelengths below the limitation of any window material. The VUV-simulator has been validated at the PTB (Physikalisch Technische Bundesanstalt) in Berlin by calibration that uses synchrotron radiation in the wavelength range between 40 and 400nm. Beside the different light sources CIF provides also electron and proton sources. Electrons and protons are generated in a low energy range from 1 to 10 keV with currents from 1 to 100 nA and in a higher range from 10 to 100 keV with 0.1 to 100 µA. Both particle sources can be operated simultaneously. In order to model temperature variations as appear in free space, the sample can be cooled down to liquid Nitrogen and heated up to about 450 K during irradiation. The complete facility has been manufactured in UHV-technology with metal sealing. It is free of organic compounds to avoid self-contamination. The different pumping systems achieve a final pressure of 1*1010 mbar (empty sample chamber) Besides the installed radiation sensors that control the stability of the various radiation sources and an attached mass spectrometer for analyzing the outgassing processes in the chamber, the construction of CIF allows adding other in-situ measurement systems to measure parameters that are of the user’s interest. We are currently planning to develop an in-situ measurement system in order to determine changes in the optical properties of the samples caused by irradiation. Within this paper we will show the design of CIF in more detail and discuss the performance of the various radiation sources

Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching

The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~\n20 ps. The radiative rate enhancement results in a 5.5-fold-improved fluorescence quantum efficiency. Exploiting the unique brightness, we have recorded the first photon antibunching of a single light-harvesting complex under ambient conditions, showing that the 27 bacteriochlorophylls coordinated by LH2 act as a non-classical single-photon emitter. The presented bright antenna-enhanced LH2 emission is a highly promising system to study energy transfer and the role of quantum coherence at the level of single complexes

Erstsemesterbefragung an der TH Wildau WS 2013/2014

Die Befragung von Studierenden gegen Ende des ersten Fachsemesters hat sich an der Technischen Hochschule Wildau (THWi)als wichtige Informationsquelle für unterschiedliche Hochschulbereiche bewährt. Den Studiengängen wird dadurch die Zufriedenheit ihrer Studierenden gespiegelt, das Hochschulmarketing erhält Rückmeldungen über die Wirksamkeit ihrer Öffentlichkeitsarbeit, und insgesamt zeigen sich wichtige Gründe, weshalb sich die Erstsemester gerade für die THWi entschieden haben. Im Vergleich zu den Vorjahren basieren die vorliegenden Befunde auf einer inhaltlich deutlich erweiterten und methodisch hinsichtlich Validität und Reliabilität der Daten überarbeiteten Fassung. Die Neukonzeption des Befragungsinstruments, die Datenerhebung sowie die statistische Analyse mittels SPSS verantwortet das Zentrum für Studienorientierung und -beratung. Die Befragung wurde zum insgesamt sechsten Mal vom 12/2013 bis zum 03/2014 in Form eines nicht öffentlichen Online-Fragebogens durchgeführt. Alle Erstsemester wurden postalisch und zusätzlich per E-Mail aufgefordert, an der Erhebung teilzunehmen. Einen Anreiz zur Teilnahme boten attraktive Gewinne, die unter allen teilnehmenden Studierenden verlost wurden. Insgesamt haben sich von 1.200 Erstsemester-Studierenden 425 an der Befragung beteiligt. Im Vergleich zum Vorjahr ist dies eine Steigerung von 16,5 %. Vor diesem Hintergrund erweist sich der methodische Mehraufwand als berechtigt. Die Auswertung der diesjährigen Befragung gliedert sich in zwei Teile. Teil 1 bündelt Themenkomplexe, die aus der Perspektive der Studierenden zeitlich „Vor dem Studium“ liegen und insbesondere die Studiengang- und Hochschulwahl mit beeinflussen. Teil 2 beleuchtet demgegenüber die ersten Gehversuche „Im Studium“, analysiert also Rahmenbedingungen, Herausforderungen und Zufriedenheitsaspekte der Studieneingangsphase

Resonant plasmonic nanoparticles for multicolor second harmonic imaging

Nanoparticles capable of efficiently generating nonlinear optical signals, like second harmonic generation, are attracting a lot of attention as potential background-free and stable nano-probes for biological imaging. However, second harmonic nanoparticles of different species do not produce readily distinguishable optical signals, as the excitation laser mainly defines their second harmonic spectrum. This is in marked contrast to other fluorescent nano-probes like quantum dots that emit light at different colors depending on their sizes and materials. Here, we present the use of resonant plasmonic nanoparticles, combined with broadband phase-controlled laser pulses, as tunable sources of multicolor second harmonic generation. The resonant plasmonic nanoparticles strongly interact with the electromagnetic field of the incident light, enhancing the efficiency of nonlinear optical processes. Because the plasmon resonance in these structures is spectrally narrower than the laser bandwidth, the plasmonic nanoparticles imprint their fingerprints on the second harmonic spectrum. We show how nanoparticles of different sizes produce different colors in the second harmonic spectra even when excited with the same laser pulse. Using these resonant plasmonic nanoparticles as nano-probes is promising for multicolor second harmonic imaging while keeping all the advantages of nonlinear optical microscopy.Peer ReviewedPostprint (published version