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Friedrich August Wolf posits in his "Prolegomena ad Homerum" that, from the time of the first transcription of Homer's epics around 700 BC to the time of the Alexandrian editions, the Iliad and Odyssey underwent repeated revisions by a multitude of poets and critics. According to Wolf, the "unified" works that we know are the products of emendations by Alexandrian critics who attempted to homogenize the style of the epics and to return them to their "original" form. This paper argues that Wolf's narration of the history of these texts relies on and produces aesthetic claims, not historical ones. Wolf determines the dates and origins of passages based on intuitive judgments of style for which he cannot provide linguistic or historical evidence. And his conclusions that the "Iliad" and "Odyssey" were not written by Homer, but rather by a history of emendations and revisions, enthrones his work — the work of philologists — in place of the literary genius Homer. Thus philology becomes for Wolf an aesthetic discipline that produces canonical and beautiful works of literature. This aesthetic task is essential for philology to fulfill its educational and political responsibilities.
This paper seeks to demonstrate the ways in which Bachmann's work constitutes a prime case for examining the scope and the boundaries of philological research. It does so by focusing on Bachmann‘s fragmentary and unfinished novel, "Das Buch Franza" [1965-1966], exploring the text and its author in an interdisciplinary light. Forming part of Bachmann's uncompleted "Todesarten"-Projekt, "Das Buch Franza" deals with the continuing legacy of fascism and its displaced forms in the post-war era. In its thematisation of the traumatic and necessarily belated after-effects of the Second World War and the Holocaust, Bachmann‘s text draws on various disciplines and discourses, namely geology, archaeology and psychoanalysis. I consider the ways in which the interdisciplinary ambitions of the text reflect Bachmann‘s struggle for a new form of representation, one that adequately mirrors the concerns of her society. Finally, drawing on Bachmann‘s own theoretical reflections on the field of literary study in her Frankfurt Lectures on poetics, I trace the ways in which the author's work repeatedly encourages us to adopt multiple disciplinary perspectives, as well as privileging literature with a utopian function that exceeds any generic or disciplinary boundaries.
Time-resolved spectroscopic analysis of fucoxanthin-chlorophyll proteins and isolated carotenoids
(2011)
The aim of this thesis was to elucidate the excitation energy transfer in the fucoxanthin-chlorophyll proteins (FCPs) isolated from the diatom Cyclotella meneghiniana in detail and to clarify the role of the different pigments contained. In a first step the excited state dynamics of the free pigments were studied by means of time-resolved absorption spectroscopy. The FCPs contain three different carotenoid species. Besides the main light-harvesting carotenoid fucoxanthin (fx) the xanthophyll cycle pigments diadinoxanthin (ddx) and diatoxanthin (dtx) are found in substoichiometric amounts. Fx is contained in an unusual carotenoid-to-chlorophyll ratio of about one. In case of ddx and dtx, changing the solvent polarity showed no significant effects on the absorption spectrum and the excited state dynamics were hardly influenced. In contrast, a solvent dependence is observed in the absorption spectrum and excited state dynamics of fx. The S1 lifetime depends strongly on the solvent polarity and an additional broad excited state absorption band red shifted compared to the S1 excited state absorption appears. The occurrence of the described features can be explained with an intramolecular charge transfer state, which is stabilized in a polar environment and appears only in carotenoids with a conjugated carbonyl group. Despite its rather short excited state lifetimes of less than 200 fs (S2) and 30-60 ps (S1), fx acts as a very efficient energy donor in the FCPs. The ultrafast energy transfer dynamics of the isolated proteins FCPa and FCPb were investigated in a comprehensive study using transient absorption in the visible and NIR spectral region complemented with polarized transient absorption spectroscopy. The excitation energy transfer was not influenced significantly by changing the light conditions during the growth, which yields an altered amount of ddx and dtx. It can be concluded that the contribution of the xanthophyll cycle pigments to the energy transfer is not significant. The altered oligomerization state results in a more efficient energy transfer for the trimeric FCPa, which is also reflected in different Chl a fluorescence quantum yields. Thus, an increased quenching in the higher oligomers of FCPb can be assumed. The observed dynamics change drastically for two different excitation wavelengths λ = 500 nm and λ = 550 nm, which both lead to the population of the S2 excited state of individual carotenoids, namely blue and red absorbing fx molecules. The differing absorption maxima result from distinct microenvironments within the protein. For FCPa an additional slow time constant of 25 ps was found after excitation at 500 nm. By means of polarized transient absorption spectroscopy applied to FCPa different transition dipole moments for the S1 and the ICT state of fx could be identified. Based on the presented studies a detailed model explaining the excitation energy transfer pathways could be developed. In agreement with the faster overall transfer rate which is also evident in the anisotropy data in case of 550 nm excitation, upon excitation at 500 nm one slow transfer channel is active. It can be attributed to a blue absorbing fx not strongly associated with a Chl a molecule. Most likely excitation energy transfer takes place between the S1/ICT states of two different fx molecules before the energy is transferred to Chl a. Additional transient absorption experiments with an improved time resolution were performed to investigate the oscillations observed. These coherent effects superimposed the kinetics of isolated carotenoids as well as FCPs within the first 500 fs. The oscillations showed a very unusual damping behavior and vanished already after two oscillation periods. In case of fx, the solvent environment as well as the excitation wavelengths had an influence on the oscillations. The frequencies of the oscillations were 70-100 cm^-1 for fx in solvents with varying polarity and 50-80 cm^-1 for the FCPs. These results could further confirm the assumption that the red absorbing fx molecules are located in a more polar environment within the protein compared to the blue absorbing fx. To clarify the origin of the oscillations in more detail, further experiments with a controlled chirp of the applied pulses and comparison between different carotenoids in various solvents are required. This approach promises to give further insight in the excited state dynamics and to answer the question whether dark states are involved. Right now, the coherent excitation of the strongly coupled excited states 1Bu+ (S2) and 1Bu- resulting in electronic quantum beats and the existence of an additional short lived excited state absorption (S2-SN2) in the visible spectral region are the most reasonable explanations for the occurrence of the coherent effects in the transient absorption spectra of carotenoids.
Capturing the zero: a new class of zero-augmented distributions and multiplicative error processes
(2011)
We propose a novel approach to model serially dependent positive-valued variables which realize a non-trivial proportion of zero outcomes. This is a typical phenomenon in financial time series observed at high frequencies, such as cumulated trading volumes. We introduce a flexible point-mass mixture distribution and develop a semiparametric specification test explicitly tailored for such distributions. Moreover, we propose a new type of multiplicative error model (MEM) based on a zero-augmented distribution, which incorporates an autoregressive binary choice component and thus captures the (potentially different) dynamics of both zero occurrences and of strictly positive realizations. Applying the proposed model to high-frequency cumulated trading volumes of both liquid and illiquid NYSE stocks, we show that the model captures the dynamic and distributional properties of the data well and is able to correctly predict future distributions.
Since combinatorial chemistry and high throughput screening have become a common technique in the drug discovery phase the number of compounds being considered has increased frequently. These structures are often characterized by high molecular weight, high lipophilicity and low solubility in aqueous and physiological media. Due to the generally poor bioavailability, new in vitro techniques were needed for screening of pharmacokinetic properties. An important parameter for these screening methods is the implementation at an early state of drug discovery phase, to find potential lead structures, before investment costs become significant. The established in vitro methods for the prediction of membrane interaction are not reliable especially for poorly soluble compounds. A new method that is fast and easy to use, requires only small amounts of NCE and which can provide more reliable predictions is needed. In this study, a new screening technique based on surface activity profiling for the prediction of oral drug absorption was evaluated with special emphasis on the predictability of biological membrane interaction of poorly soluble drug compounds. It was demonstrated that drug absorption through a bilayer membrane can be modeled by the orientation of compounds at the air/water interface. Thus amphilicity of a drug is generally related to both oral absorption and blood brain barrier penetration. In turn, amphiphilicity is influenced by the lipophilicity, size and charge distribution of a drug. Surface activity profiling was determined by analysis of surface pressure profiles using the Gibbs adsorption isotherm. The surface activity measurements were carried out using a multichannel tensiometer Delta 8, which was developed by Kibron to be utilized in conjugation high throughput screening in early drug discovery processes. For this study two test sets were analyzed, one for the prediction of gastrointestinal wall interaction and the second for the prediction of the penetration behavior at the blood brain barrier. Both test sets consist of drug compounds with a wide range of absorption properties and consist mainly of compounds with poor water solubility. Since the drugs characteristics varied, they were classified according to water solubility and surface activity and a sample preparation method for each group was established. For the prediction of oral drug absorption, three different methods were established to model the interaction of compound and gastrointestinal wall. For drug compounds with solubility above 1mmol/L the traditional shake-flask method enabled the determination of the amphiphilic properties of drug compounds in pure aqueous media. Compounds with solubility below 1mmol/L tend to not to exhibit any increase in surface activity. Thus surface tension measurements of compounds, which exhibited a limited surface activity due to poor aqueous solubility, were conducted from stock solutions prepared with various organic solvents. Mainly polar organic solvents were used. A mixture of DMSO and DMF resulted in the best combination of properties: the intensive solubility enhancing effect of DMF and the lower intrinsic surface activity of DMSO. The polar solvent ruptured the water clusters, so that highly lipophilic structures had a higher affinity to the solvent and higher concentrations could be obtained. For these compounds higher maximum surface pressure were generated than was possible in pure aqueous media. The surface pressure data were correlated with the fraction absorbed values in vivo. However it was found that poor water solubility is not the only limiting step to exhibiting any surface activity. Some compounds were showed no surface activity in either solvent system. Therefore a micelle vehicle method was established using short chain phospholipids to mimic the gastrointestinal wall. It could be concluded from the results, that non surface active drugs can interact with the phospholipids micelle vehicle in a way analogous to their interaction with the membrane bilayer. The relative critical micelle concentration was correlated with the fraction absorbed of this test set. A sample preparation schema based on the three types of drugs was established. This schema enabled us to predict the absorbance of slightly soluble and poorly soluble drugs with acceptable reliability for early compound screening. For the prediction of blood brain barrier penetration using surface activity profiling as analyzing method, a test set with very poorly soluble characteristics was chosen. The sample preparation method was based on a strictly aqueous approach using the ‘shake flask’ method. The surface tension measurements enabled correlation of the amphiphilic properties of the very poorly soluble drug compounds with BBB uptake. From the aqueous surface pressure profiles and the determination of physicochemical parameters, it was found that blood brain barrier is more likely when a drug provides a small cross-sectional area, As, at the interface. The cross-sectional area is the only parameter which is independent from the maximal concentration in aqueous media and it is particularly suitable for lower solubility compounds. In summary, it was shown that amphilicity is related to biological membrane interaction in the human body and that surface activity profiling with appropriate sample preparation can be used as a reliable screening tool for the prediction of oral drug absorption of poorly soluble drugs. Furthermore an in vitro screening method of blood-brain-barrier penetration was established.
This paper addresses the open debate about the usefulness of high-frequency (HF) data in large-scale portfolio allocation. Daily covariances are estimated based on HF data of the S&P 500 universe employing a blocked realized kernel estimator. We propose forecasting covariance matrices using a multi-scale spectral decomposition where volatilities, correlation eigenvalues and eigenvectors evolve on different frequencies. In an extensive out-of-sample forecasting study, we show that the proposed approach yields less risky and more diversified portfolio allocations as prevailing methods employing daily data. These performance gains hold over longer horizons than previous studies have shown.
This article reports on the second Young Environmental Scientists Meeting that was hosted from 28 February to 2 March 2011 by the Institute for Environmental Research at RWTH Aachen University, Germany. This extraordinary meeting was again initiated and organized by the Student Advisory Council under the umbrella of Society of Environmental Toxicology and Chemistry Europe. A movie about the meeting and the abstracts of poster and platform presentations are freely available as supplemental material of this article.
Background: We aimed to investigate the influences of attention deficit/hyperactivity disorder (ADHD) on response evaluation, as reflected by the postimperative negative variation (PINV), a slow event-related potential. Methods: We investigated PINV as an indicator of performance uncertainty in an audio-visual contingent negative variation (CNV) paradigm with an interstimulus interval of 3 seconds. A constant, unilateral, quick motor reaction with either the right or the left thumb was required after an auditory forewarned (S1) visual imperative stimulus (S2). We examined 18 ADHD patients (combined or hyperactive-impulsive subtype) aged between 8 and 14 years and an age-, sex and IQ-matched control group of 19 healthy subjects using 64-channel high-density EEG. A first run was recorded drug-free, a second one under methylphenidate (MPH) medication in the ADHD group. Results: We found a significantly increased negativity of the PINV-component over the ventrolateral prefrontal cortex in ADHD children compared to the healthy control group. PINV amplitude was influenced by movement side, most likely due to the slightly more difficult task when left hand responses were required. After the intake of MPH, PINV amplitudes of ADHD children normalized. Conclusions: We conclude that children with ADHD are likely to be more uncertain about the correctness of their performance and interpret the increased PINV as a hint towards compensatory mechanisms for a deficit in the evaluation of contingencies. Further studies are needed to assess the exact extent to which remainders of eye-movement related potentials contribute to PINV amplitude despite the correction for eye-artifacts.
Introduction: Endovascular aortic repair, if technically feasible, is the treatment of choice for patients with a contained ruptured aortic aneurysm who are unfit for open surgery. Case presentation: We report the case of an 80-year-old Caucasian man who presented with an unusually configured, symptomatic infrarenal aortic aneurysm. His aneurysm showed an erosion of the fourth lumbar vertebra and a severely arteriosclerotic pelvic axis. A high thigh amputation of his right leg had been performed 15 months previously. On his right side, occlusion of his external iliac artery, common femoral artery, and deep femoral artery had occurred. His aneurysm was treated by a left-sided aortomonoiliac stent graft without femorofemoral revascularization, resulting in occlusions of both internal iliac arteries. No ischemic symptoms appeared, although perfusion of his right side was maintained only over epigastric collaterals. Conclusions: The placement of aortomonoiliac stent grafts for endovascular treatment of infrarenal aortic aneurysms without contralateral revascularization is a feasible treatment option in isolated cases. In this report, access problems and revascularization options in endovascular aneurysm repair are discussed.
The direct financial impact of the financial crisis has been to deal a heavy blow to investment-based pensions; many workers lost a substantial portion of their retirement saving. The financial sector implosion produced an economic crisis for the rest of the economy via high unemployment and reduced labor earnings, which reduced household contributions to Social Security and some private pensions. Our research asks which types of individuals were most affected by these dual financial and economic shocks, and it also explores how people may react by changing their consumption, saving and investment, work and retirement, and annuitization decisions. We do so with a realistically calibrated lifecycle framework allowing for time-varying investment opportunities and countercyclical risky labor income dynamics. We show that households near retirement will reduce both short- and long-term consumption, boost work effort, and defer retirement. Younger cohorts will initially reduce their work hours, consumption, saving, and equity exposure; later in life, they will work more, retire later, consume less, invest more in stocks, save more, and reduce their demand for private annuities. Keywords: Financial Crisis , Household Finance , Cycle Portfolio Choice , Labor Supply Classification: D1, G11, G23, G35, J14, J26, J32