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Photochromism is the phenomenon that mocules can undergo reversible changes in their structure with light of a specific wavelength. Among a number of photochromic molecules, dithienylcyclopentene (DCP) is a molecular switch which undergoes a cyclization (ring-closing) reaction upon illumination with light in the ultraviolet (UV) spectral range. The cycloreversion (ring-opening) reaction is accomplished by illumination with light in the visible range. Such photochromic reactions can be useful for the application in two major fields. The first field is the application in molecular electronics, where their function as a switch can be exploited by designing transistors, gates, logic circuits, or even devices assembled thereof. The second big field of application is super-resolution microscopy. Special techniques are relying on the digital bright/dark- or on-/off-toggling of the fluorescence of single molecules in the sample in order to identify and localize single molecule fluorescence as single bright spots. Currently, most techniques rely on stochastic molecular processes causing intermittency in single molecule fluorescence. Photochromic switches with their ability to be deliberately switched feature a clear advantage. In this dissertation, photochromic triads consisting of one DCP and two covalently linked fluorophores, are examined. The triads are tailor-made macromolecules designed in such a way that the the state of the switch is monitored by the fluorescence of the fluorophores, which is quenched if the DCP is in its closed state due to an energy transfer from the fluorophores to the photochromic switch. Monitoring of the fluorescence means the use of confocal fluorescence microscopy in order to reveal the characteristics of the switching processes for ensembles and single triads. As tens or hundreds of thousand of photochromic triads are present in ensemble samples where the triads are immobilised in a polymer matrix, the fluorescence will decrease exponentially upon UV illumination, and increase with a saturated exponential growth when the UV illumination is ceased and only visible illumination excites the triads to fluorescence, each described by rate equations. This is in stark contrast for the switching of single triads, where a digital change between a highly fluorescent “On”-state and a weakly fluorescent “Off”-state is expected. A summary of those concepts is given, and additionally an experimental strategy for the switching of single photochromic triads is presented, where the focus lies on a slowed switching reaction. This is achieved making use of special triads and the conduction of experiments at low temperatures. The slowed reaction at low temperatures is of crucial interest for the experiments presented in two chapters, where the experimental focus lies on the detection of single molecule switching. In the first of these chapters, triads composed of a DCP switch and two strong perylene bisimide (PBI) fluorophores were used. The triads were immobilised in a polymer matrix and cooled down to 10K. The single triads are initialized in their closed, non-fluorescent state with UV illumination, which is then probed by visible illumination. As the triad will cycle excitation and radiationless decay in its closed form and then, after a statistically distributed time, undergo the cycloreversion reaction, the fluorescence will be delayed with respect to the onset of probe illumination. One measurement contained 400 switching cycles. However, also unavoidable stochastic blinking processes lead to a quenching of the fluorescence of the triads, and obscure the distribution of fluorescence delay times. This is why a control experiment of the same length was conducted and a statistical model of conditional probabilities was applied in order to distinguish between deliberate switching and stochastic blinking presenting the positive predictive value (PPV). It was found that on the average over 15 single triads, the PPV amounts to 0.8±0.1, the probability which can be assigned to deliberate switching rather than blinking for the triads measured. In the second chapter dealing with single molecule switching, the single molecule measurements were continued with the known triads with PBI moieties as fluorophores, and additionally triads that use boron dipyrromethene (BODIPY) as fluorophores were examined, and as many on-/off-cycles were probed as possible. As a result, the corresponding average PPV for 20 DCP-PBI and 18 DCP-BODIPY triads of 0.7±0.1 is - on the average - the same for both kinds of triads. Furthermore, this PPV was confirmed to be in the same range as for the one in the preceding chapter . In addition, the many repetitions of the measurement pairs switching experiment/control experiment lead to the conclusion that several thousands of switching cycles per triad are possible, showing a remarkably high fatigue resistance of the switching process.

We theoretically show that there is a fundamental disconnect be- tween the disposition effect, i.e., investors' tendency to sell winning assets too early and losing assets too late, and its common empirical measure, namely a positive difference between the proportion of gains and losses re- alized. While its common measure cannot identify the disposition effect, it identifies the presence of some systematic bias. We further investigate the measure's comparative statics regarding markets, investors' information level, and their attention. Besides generating novel testable predictions, this analysis reveals that, in contrast to the measure's sign, variations in its magnitude are informative for its cause.

We theoretically show that there is a fundamental disconnect between the disposition effect, i.e., investors��� tendency to sell winning assets too early and losing assets too late, and its common empirical measure, namely a positive difference between the proportion of gains and losses realized. While its common measure cannot identify the disposition effect, it identifies the presence of some systematic bias. We further investigate the measure���s comparative statics regarding markets, investors��� information level, and their attention. Besides generating novel testable predictions, this analysis reveals that, in contrast to the measure���s sign, variations in its magnitude are informative for its cause, Disposition Effect, Rational Benchmark, Investor Behavior, Behavioral Biases, Market Segments, Financial Attention, Information Level

The purpose of this study was to evaluate the quality of surface contouring of chondromalacic cartilage by bipolar radio frequency energy using different treatment patterns in an animal model, as well as examining the impact of the treatment onto chondrocyte viability by two different methods. Our experiments were conducted on 36 fresh osteochondral sections from the tibia plateau of slaughtered 6-month-old pigs, where the thickness of the cartilage is similar to that of human wrist cartilage. An area of 1 cm(2) was first treated with emery paper to simulate the chondromalacic cartilage. Then, the treatment with RFE followed in 6 different patterns. The osteochondral sections were assessed for cellular viability (live/dead assay, caspase (cell apoptosis marker) staining, and quantitative analysed images obtained by fluorescent microscopy). For a quantitative characterization of none or treated cartilage surfaces, various roughness parameters were measured using confocal laser scanning microscopy (Olympus LEXT OLS 4000 3D). To describe the roughness, the Root-Mean-Square parameter (Sq) was calculated. A smoothing effect of the cartilage surface was detectable upon each pattern of RFE treatment. The Sq for native cartilage was Sq=3.8 +/- 1.1 mu m. The best smoothing pattern was seen for two RFE passes and a 2-second pulsed mode (B2p2) with an Sq=27.3 +/- 4.9 mu m. However, with increased smoothing, an augmentation in chondrocyte death up to 95% was detected. Using bipolar RFE treatment in arthroscopy for small joints like the wrist or MCP joints should be used with caution. In the case of chondroplasty, there is a high chance to destroy the joint cartilage.

Background: The aim of the study was to compare the two irradiation modes with (FF) and without flattening filter (FFF) for three different treatment techniques for simultaneous integrated boost radiation therapy of patients with right sided breast cancer. Methods: An Elekta Synergy linac with Agility collimating device is used to simulate the treatment of 10 patients. Six plans were generated in Monaco 5.0 for each patient treating the whole breast and a simultaneous integrated boost (SIB) volume: intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and a tangential arc VMAT (tVMAT), each with and without flattening filter. Plan quality was assessed considering target coverage, sparing of the contralateral breast, the lungs, the heart and the normal tissue. All plans were verified by a 2D-ionisation-chamber-array and delivery times were measured and compared. The Wilcoxon test was used for statistical analysis with a significance level of 0.05. Results: Significantly best target coverage and homogeneity was achieved using VMAT FFF with V95% = (98.7 +/- 0.8) % and HI = (8.2 +/- 0.9) % for the SIB and V95% = (98.3 +/- 0.7) % for the PTV, whereas tVMAT showed significantly lowest doses to the contralateral organs at risk with a D-mean of (0.7 +/- 0.1) Gy for the contralateral lung, (1.0 +/- 0.2) Gy for the contralateral breast and (1.4 +/- 0.2) Gy for the heart. All plans passed the gamma evaluation with a mean passing rate of (99.2 +/- 0.8) %. Delivery times were significantly reduced for VMAT and tVMAT but increased for IMRT, when FFF was used. Lowest delivery times were observed for tVMAT FFF with (1:20 +/- 0:07) min. Conclusion: Balancing target coverage, OAR sparing and delivery time, VMAT FFF and tVMAT FFF are considered the preferable of the investigated treatment options in simultaneous integrated boost irradiation of right sided breast cancer for the combination of an Elekta Synergy linac with Agility and the treatment planning system Monaco 5.0.

We propose a model of instrumental belief choice under loss aversion. When new information arrives, an agent is prompted to abandon her prior. However, potential posteriors may induce her to take actions that generate a lower utility in some states than actions induced by her prior. These losses loom larger than gains in other states in which potential posteriors lead to larger utility than the prior. In choosing her belief, the agent optimally trades off these psychological gains and losses against the belief's objective performance. Consistent with empirical evidence, belief updating in this model is conservative and can be asymmetric, so that bad news is updated more conservatively than good news. These updating biases generate prior-dependent information preferences, such that agents may avoid information when being unconfident but are information seeking otherwise. Because belief updating depends on the decision problem in which new information is going to be used, the model allows us to explore how these predictions change with either individual preferences or the choice context.