Nonlinear dielectric response of Debye, alpha, and beta relaxation in 1-propanol

We present nonlinear dielectric measurements of glass-forming 1-propanol, a prototypical example for the monohydroxy alcohols that are known to exhibit unusual relaxation dynamics, namely an additional Debye relaxation, slower than the structural alpha relaxation. Applying high ac fields of 468 kV/cm allows for a detailed investigation of the nonlinear properties of all three relaxation processes occurring in 1-propanol, namely the Debye, alpha, and beta relaxation. Both the field-induced variations of dielectric constant and loss are reported. Polarization saturation and the absorption of field energy govern the findings in the Debye-relaxation regime, well consistent with the suggested cluster-like nature of the relaxing entities. The behavior of the alpha relaxation is in good accord with the expectations for a heterogeneous relaxation scenario. Finally, the Johari-Goldstein beta-relaxation in 1-propanol seems to exhibit no or only weak field dependence, in agreement with recent findings for the excess wing of canonical glass formers.Comment: 8 pages, 4 figure

Cooperativity and Heterogeneity in Plastic Crystals Studied by Nonlinear Dielectric Spectroscopy

The glassy dynamics of plastic-crystalline cyclo-octanol and ortho-carborane, where only the molecular reorientational degrees of freedom freeze without long-range order, is investigated by nonlinear dielectric spectroscopy. Marked differences to canonical glass formers show up: While molecular cooperativity governs the glassy freezing, it leads to a much weaker slowing down of molecular dynamics than in supercooled liquids. Moreover, the observed nonlinear effects cannot be explained with the same heterogeneity scenario recently applied to canonical glass formers. This supports ideas that molecular relaxation in plastic crystals may be intrinsically non-exponential. Finally, no nonlinear effects were detected for the secondary processes in cyclo-octanol.Comment: Final version as accepted for publication in Phys. Rev. Lett. 6 pages, 5 figures (including 1 page and figure in Supplemental Material

Cognitive and affective determinants of entrepreneurial decisions experimentally examined

Objectives. Our study investigates the role of emotions and cognitions in the pre-entrepreneurial decision-making process, i.e., the process prior to the decision to exploit an entrepreneurial opportunity, which has only looked at by few researchers so far. Methods. An online questionnaire experiment with three different samples, i.e., employees, students, and entrepreneurs (N = 578) using 16 different experimentally manipulated entrepreneurial scenarios was conducted. Results. Findings indicate that the relationship between the characteristics of an entrepreneurial opportunity and the evaluation of it is mediated by cognitive appraisals. Moreover, negative and positive affects moderate the relationship between the evaluation of an entrepreneurial opportunity and the decision to exploit it. Conclusion. This study confirms the central assumption of cognitive appraisal theories of emotion which state that the subjective representation of objective entrepreneurial opportunities better predicts the decision to exploit an entrepreneurial opportunity than the objective characteristics of the entrepreneurial situation

Optimal control of Allen-Cahn systems

Optimization problems governed by Allen-Cahn systems including elastic effects are formulated and first-order necessary optimality conditions are presented. Smooth as well as obstacle potentials are considered, where the latter leads to an MPEC. Numerically, for smooth potential the problem is solved efficiently by the Trust-Region-Newton-Steihaug-cg method. In case of an obstacle potential first numerical results are presented

Quantitative PCR assay for detection of Bois noir phytoplasmas in grape and insect tissue

In Europe's vineyards "Bois noir" (BN) is an expanding yellows disease on Vitis vinifera. It is associated with phytoplasmas of the stolbur group (16SrXII-A). Two subtypes are important, one is associated with Urtica dioica and one with Convolvulus arvensis. Both phytoplasma types are transmitted by the insect Hyalesthes obsoletus. A nucleic acid extraction method for V. vinifera and H. obsoletus was developed together with a real time PCR (qPCR) assay based on a polymorphic sequence with homology to a putative dimethyladenosine transferase. The comparison of the conventional detection method with the qPCR assay of 40 insect and 40 V. vinifera samples showed a 10 % higher sensitivity of qPCR in plant samples. The titer of phytoplasmas in H. obsoletus was 2643-fold increased in the strongest infected samples compared to the lowest ones. The results suggest this real-time PCR as a valid and fast alternative procedure for the detection and quantification of BN phytoplasmas. The assay allows to discriminate the two phytoplasma types and to quantify phytoplasmas in H. obsoletus.

A rapid and inexpensive RNA-extraction method for high-throughput virus detection in grapevine

The extraction of RNA from grapevine tissue is a crucial step for virus diagnostics via multiplex reverse transcription-polymerase chain reaction (mRT-PCR). Conventional methods are either time-consuming or expensive when convenient extraction kits are used. Here we present an easy, but reliable extraction method that fulfills the requirements of epidemiological research (high sample throughput with maximum accuracy). A further advantage of the protocol beside the low costs is the absence of harmful chemicals like phenol or chloroform and the possibility to manage 'high-throughput' extractions and analyses

Die limitierte Auflage: Rechtsfragen zeitgenössischer Fotokunst

Over the course of the past decades, photography has become one of the most popular fields of art. This development is also reflected in recent prices for some works of contemporary photography, which fetch up to several million dollars. Such price levels would be unheard of if artists were to take advantage of the opportunity to produce as many prints from the same negative as possible. On the contrary, the prevailing practice in contemporary photography is that of printing photographs in “limited editions”, with some of the most expensive photographs only existing in the low single digits. This study researches the legal implications of artists communicating limited editions to the purchasers of their art with the main question being whether such “promises of exclusivity” are legally binding and thus could be enforced by collectors e. g. in court proceedings.Die Fotografie hat sich in den letzten Jahrzehnten zu einer der populärsten Kunstgattungen entwickelt. Dies zeigt sich nicht zuletzt auch am Erfolg der zeitgenössischen Fotografie auf dem Kunstmarkt, wo einzelne Abzüge mittlerweile für Millionenbeträge gehandelt werden. Diese hohe finanzielle Wertschätzung einzelner Fotografien wäre undenkbar, würde das Potenzial der Fotografie zur nahezu unendlichen Reproduktion tatsächlich ausgeschöpft. Im Gegenteil hat sich im Bereich der zeitgenössischen Fotokunst die Praxis etabliert, Fotografien nur in sogenannten „limitierten Auflagen“ aufzulegen, bei denen teilweise sogar mit einstelligen Auflagenhöhen gearbeitet wird. Die vorliegende Dissertation untersucht die rechtlichen Fragen im Zusammenhang mit solchen Auflagenlimitierungen und geht dabei insbesondere der Frage nach, ob solche Exklusivitätsversprechen“ rechtlich bindend sind und somit beispielsweise von einem Sammler eingeklagt werden könnten

Intuitive Understanding of sigma Delocalization in Loose and sigma Localization in Tight Helical Conformations of a Saturated Chain Oligosilanes

Conformational effects on the amp; 963; electron delocalization in oligosilanes are addressed by Hartree Fock and time dependent density functional theory calculations B3LYP, 6 311G at MP2 optimized geometries of permethylated uniformly helical linear oligosilanes all amp; 969; SinR2n 2 up to n 16 and for backbone dihedral angles amp; 969; 55 180 . The extent of amp; 963; delocalization is judged by the partition ratio of the highest occupied molecular orbital and is reflected in the dependence of its shape and energy and of UV absorption spectra on n. The results agree with known spectra of all transoid loose helix conformers all [ 165] SinMe2n 2 and reveal a transition at amp; 969; amp; 8776;90 from the amp; 963; delocalized limit at amp; 969; 180 toward and close to the physically non realizable amp; 963; localized tight helix limit amp; 969; 0 with entirely different properties. The distinction is also obtained in the Hückel Ladder H and C models of amp; 963; delocalization. An easy intuitive way to understand the origin of the two contrasting limits is to first view the linear chain as two subchains with alternating primary and vicinal interactions amp; 963; hyperconjugation , one consisting of the odd and the other of the even amp; 963; SiSi bonds, and then allow the two subchains to interact by geminal interactions amp; 963; conjugatio

Fifth-order susceptibility unveils growth of thermodynamic amorphous order in glass-formers

Glasses are ubiquitous in daily life and technology. However the microscopic mechanisms generating this state of matter remain subject to debate: Glasses are considered either as merely hyper-viscous liquids or as resulting from a genuine thermodynamic phase transition towards a rigid state. We show that third- and fifth-order susceptibilities provide a definite answer to this longstanding controversy. Performing the corresponding high-precision nonlinear dielectric experiments for supercooled glycerol and propylene carbonate, we find strong support for theories based upon thermodynamic amorphous order. Moreover, when lowering temperature, we find that the growing transient domains are compact - that is their fractal dimension d_f = 3. The glass transition may thus represent a class of critical phenomena different from canonical second-order phase transitions for which d_f < 3.Comment: 9 pages, 3 figure