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Cell-free protein synthesis as a novel tool for directed glycoengineering of active erythropoietin
(2018)
As one of the most complex post-translational modification, glycosylation is widely involved in cell adhesion, cell proliferation and immune response. Nevertheless glycoproteins with an identical polypeptide backbone mostly differ in their glycosylation patterns. Due to this heterogeneity, the mapping of different glycosylation patterns to their associated function is nearly impossible. In the last years, glycoengineering tools including cell line engineering, chemoenzymatic remodeling and site-specific glycosylation have attracted increasing interest. The therapeutic hormone erythropoietin (EPO) has been investigated in particular by various groups to establish a production process resulting in a defined glycosylation pattern. However commercially available recombinant human EPO shows batch-to-batch variations in its glycoforms. Therefore we present an alternative method for the synthesis of active glycosylated EPO with an engineered O-glycosylation site by combining eukaryotic cell-free protein synthesis and site-directed incorporation of non-canonical amino acids with subsequent chemoselective modifications.
Cell-free protein synthesis as a novel tool for directed glycoengineering of active erythropoietin
(2018)
As one of the most complex post-translational modification, glycosylation is widely involved in cell adhesion, cell proliferation and immune response. Nevertheless glycoproteins with an identical polypeptide backbone mostly differ in their glycosylation patterns. Due to this heterogeneity, the mapping of different glycosylation patterns to their associated function is nearly impossible. In the last years, glycoengineering tools including cell line engineering, chemoenzymatic remodeling and site-specific glycosylation have attracted increasing interest. The therapeutic hormone erythropoietin (EPO) has been investigated in particular by various groups to establish a production process resulting in a defined glycosylation pattern. However commercially available recombinant human EPO shows batch-to-batch variations in its glycoforms. Therefore we present an alternative method for the synthesis of active glycosylated EPO with an engineered O-glycosylation site by combining eukaryotic cell-free protein synthesis and site-directed incorporation of non-canonical amino acids with subsequent chemoselective modifications.
We investigated the influence of the emitter (amorphous-Si, a-Si, or polythiophene derivatives: poly(3-hexylthiophene), P3HT, and poly(3-[3,6-dioxaheptyl]-thiophene), P3DOT) and the interface passivation (intrinsic a-Si or SiOX and methyl groups or SiOX) on the c-Si based 1 × 1 cm2 planar hybrid heterojunction solar cell parameters. We observed higher short circuit currents for the P3HT or P3DOT/c-Si solar cells than those obtained for a-Si/c-Si devices, independent of the interface passivation. The obtained VOC of 659 mV for the P3DOT/SiOX/c-Si heterojunction solar cell with hydrophilic 3,6-dioxaheptyl side chains is among the highest reported for c-Si/polythiophene devices. The maximum power conversion efficiency, PCE, was 11% for the P3DOT/SiOX/c-Si heterojunction solar cell. Additionally, our wafer lifetime measurements reveal a field effect passivation in the wafer induced by the polythiophenes when deposited on c-Si.
The Cretaceous units exposed in the northwestern segment of the Colombian Andes preserve the record of extensional and compressional tectonics prior to the collision with Caribbean oceanic terranes. We integrated field, stratigraphic, sedimentary provenance, whole rock geochemistry, Nd isotopes and U-Pb zircon data to understand the Cretaceous tectonostratigraphic and magmatic record of the Colombian Andes. The results suggest that several sedimentary successions including the Abejorral Fm. were deposited on top of the continental basement in an Early Cretaceous backarc basin (150-100 Ma). Between 120 and 100 Ma, the appearance of basaltic and andesitic magmatism (similar to 115-100 Ma), basin deepening, and seafloor spreading were the result of advanced stages of backarc extension. A change to compressional tectonics took place during the Late Cretaceous (100-80 Ma). During this compressional phase, the extended blocks were reincorporated into the margin, closing the former Early Cretaceous backarc basin. Subsequently, a Late Cretaceous volcanic arc was built on the continental margin: as a result, the volcanic rocks of the Quebradagrande Complex were unconformably deposited on top of the faulted and folded rocks of the Abejorral Fm. Between the Late Cretaceous and the Paleocene (80-60 Ma), an arc-continent collision between the Caribbean oceanic plateau and the South-American continental margin deformed the rocks of the Quebradagrande Complex and shut-down the active volcanic arc. Our results suggest an Early Cretaceous extensional event followed by compressional tectonics prior to the collision with the Caribbean oceanic plateau. (C) 2019 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
Background: Individuals with aphasia after stroke (IWA) often present with working memory (WM) deficits. Research investigating the relationship between WM and language abilities has led to the promising hypothesis that treatments of WM could lead to improvements in language, a phenomenon known as transfer. Although recent treatment protocols have been successful in improving WM, the evidence to date is scarce and the extent to which improvements in trained tasks of WM transfer to untrained memory tasks, spoken sentence comprehension, and functional communication is yet poorly understood.
Aims: We aimed at (a) investigating whether WM can be improved through an adaptive n-back training in IWA (Study 1–3); (b) testing whether WM training leads to near transfer to unpracticed WM tasks (Study 1–3), and far transfer to spoken sentence comprehension (Study 1–3), functional communication (Study 2–3), and memory in daily life in IWA (Study 2–3); and (c) evaluating the methodological quality of existing WM treatments in IWA (Study 3). To address these goals, we conducted two empirical studies – a case-controls study with Hungarian speaking IWA (Study 1) and a multiple baseline study with German speaking IWA (Study 2) – and a systematic review (Study 3).
Methods: In Study 1 and 2 participants with chronic, post-stroke aphasia performed an adaptive, computerized n-back training. ‘Adaptivity’ was implemented by adjusting the tasks’ difficulty level according to the participants’ performance, ensuring that they always practiced at an optimal level of difficulty. To assess the specificity of transfer effects and to better understand the underlying mechanisms of transfer on spoken sentence comprehension, we included an outcome measure testing specific syntactic structures that have been proposed to involve WM processes (e.g., non-canonical structures with varying complexity).
Results: We detected a mixed pattern of training and transfer effects across individuals: five participants out of six significantly improved in the n-back training. Our most important finding is that all six participants improved significantly in spoken sentence comprehension (i.e., far transfer effects). In addition, we also found far transfer to functional communication (in two participants out of three in Study 2) and everyday memory functioning (in all three participants in Study 2), and near transfer to unpracticed n-back tasks (in four participants out of six). Pooled data analysis of Study 1 and 2 showed a significant negative relationship between initial spoken sentence comprehension and the amount of improvement in this ability, suggesting that the more severe the participants’ spoken sentence comprehension deficit was at the beginning of training, the more they improved after training. Taken together, we detected both near far and transfer effects in our studies, but the effects varied across participants. The systematic review evaluating the methodological quality of existing WM treatments in stroke IWA (Study 3) showed poor internal and external validity across the included 17 studies. Poor internal validity was mainly due to use of inappropriate design, lack of randomization of study phases, lack of blinding of participants and/or assessors, and insufficient sampling. Low external validity was mainly related to incomplete information on the setting, lack of use of appropriate analysis or justification for the suitability of the analysis procedure used, and lack of replication across participants and/or behaviors. Results in terms of WM, spoken sentence comprehension, and reading are promising, but further studies with more rigorous methodology and stronger experimental control are needed to determine the beneficial effects of WM intervention.
Conclusions: Results of the empirical studies suggest that WM can be improved with a computerized and adaptive WM training, and improvements can lead to transfer effects to spoken sentence comprehension and functional communication in some individuals with chronic post-stroke aphasia. The fact that improvements were not specific to certain syntactic structures (i.e., non-canonical complex sentences) in spoken sentence comprehension suggest that WM is not involved in the online, automatic processing of syntactic information (i.e., parsing and interpretation), but plays a more general role in the later stage of spoken sentence comprehension (i.e., post-interpretive comprehension). The individual differences in treatment outcomes call for future research to clarify how far these results are generalizable to the population level of IWA. Future studies are needed to identify a few mechanisms that may generalize to at least a subpopulation of IWA as well as to investigate baseline non-linguistic cognitive and language abilities that may play a role in transfer effects and the maintenance of such effects. These may require larger yet homogenous samples.
Recent treatment protocols have been successful in improving working memory (WM) in individuals with aphasia. However, the evidence to date is small and the extent to which improvements in trained tasks of WM transfer to untrained memory tasks, spoken sentence comprehension, and functional communication is yet poorly understood. To address these issues, we conducted a multiple baseline study with three German-speaking individuals with chronic post stroke aphasia. Participants practised two computerised WM tasks (n-back with pictures and aback with spoken words) four times a week for a month, targeting two WM processes: updating WM representations and resolving interference. All participants showed improvement on at least one measure of spoken sentence comprehension and everyday memory activities. Two of them showed improvement also on measures of WM and functional communication. Our results suggest that WM can be improved through computerised training in chronic aphasia and this can transfer to spoken sentence comprehension and functional communication in some individuals.
Due to the low cutaneous bioavailability of tacrolimus (TAC), penetration enhancers are used to improve its penetration into the skin. However, poor loading capacity, non-biodegradability, toxicity, and in some cases inefficient skin penetration are challenging issues that hamper their applications for the dermal TAC delivery. Here we present poly(lactide-co-glycerol) (PLG) as a water soluble, biodegradable, and biocompatible TAC-carrier with high loading capacity (14.5% w/w for TAC) and high drug delivery efficiencies into the skin. PLG was synthesized by cationic ring-opening copolymerization of a mixture of glycidol and lactide and showed 35 nm and 300 nm average sizes in aqueous solutions before and after loading of TAC, respectively. Delivery experiments on human skin, quantified by fluorescence microscopy and LC-MS/MS, showed a high ability for PLG to deposit Nile red and TAC into the stratum corneum and viable epidermis of skin in comparison with Protopic (R) (0.03% w/w, TAC ointment). The cutaneous distribution profile of delivered TAC proved that 80%, 16%, and 4% of the cutaneous drug level was deposited in the stratum corneum, viable epidermis, and upper dermis, respectively. TAC delivered by PLG was able to efficiently decrease the IL-2 and TSLP expressions in human skin models. Taking advantage of the excellent physicochemical and biological properties of PLG, it can be used for efficient dermal TAC delivery and potential treatment of inflammatory skin diseases.
Ubiquitous business processes are the new generation of processes that pervade the physical space and interact with their environments using a minimum of human involvement. Although they are now widely deployed in the industry, their deployment is still ad hoc . They are implemented after an arbitrary modeling phase or no modeling phase at all. The absence of a solid modeling phase backing up the implementation generates many loopholes that are stressed in the literature. Here, we tackle the issue of modeling ubiquitous business processes. We propose patterns to represent the recent ubiquitous computing features. These patterns are the outcome of an analysis we conducted in the field of human-computer interaction to examine how the features are actually deployed. The patterns' understandability, ease-of-use, usefulness, and completeness are examined via a user experiment. The results indicate that these four indexes are on the positive track. Hence, the patterns may be the backbone of ubiquitous business process modeling in industrial applications.
X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (1020 W cm−2) of x-rays at wavelengths down to ~1 Ångstrom, and HHG provides unprecedented time resolution (~50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scales can be referenced to the chemically significant carbon K-edge at a photon energy of ~280 eV (44 Ångstroms) and the bond length in methane of ~1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.
X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (10(20) W cm(-2)) of x-rays at wavelengths down to similar to 1 Angstrom, and HHG provides unprecedented time resolution (similar to 50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scales can be referenced to the chemically significant carbon K-edge at a photon energy of similar to 280 eV (44 Angstroms) and the bond length in methane of similar to 1 Angstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Angstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Angstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.
The Gezi uprising can be considered a crucial turning in Turkish politics. As a response to countrywide democratic protests, the Justice and Development Party (AKP) government revived the security state, escalated authoritarian tendencies, and started to organize a nationalist, Islamist, and conservative backlash. This essay argues that the Gezi Park protests revealed both the fragility of the AKP's hegemony and the limits of the dominant political group habitus, which were promoted by the party to consolidate political polarization in favor of the party's hegemony. Moreover, it is argued that the Gezi uprising transformed the culture of political protests in the country and paved the way for the emergence of affirmative resistance, radical imagination, and a new politics of desire and dignity against authoritarian and neoliberal policies.
Plain Language Summary Cassini flew through the gap between Saturn and its rings for 22 times before plunging into the atmosphere of Saturn, ending its 20-year mission. The radio and plasma waves instrument on board Cassini helped quantify the dust hazard in this previously unexplored region. The measured density of large dust particles was much lower than expected, allowing high-value science observations during the subsequent Grand Finale orbits.
During the Ring Grazing orbits near the end of Cassini mission, the spacecraft crossed the equatorial plane near the orbit of Janus/Epimetheus (similar to 2.5 Rs). This region is populated with dust particles that can be detected by the Radio and Plasma Wave Science (RPWS) instrument via an electric field antenna signal. Analysis of the voltage waveforms recorded on the RPWS antennas provides estimations of the density and size distribution of the dust particles. Measured RPWS profiles, fitted with Lorentzian functions, are shown to be mostly consistent with the Cosmic Dust Analyzer, the dedicated dust instrument on board Cassini. The thickness of the dusty ring varies between 600 and 1,000 km. The peak location shifts north and south within 100 km of the ring plane, likely a function of the precession phase of Janus orbit.
Achieving the highest power conversion efficiencies in bulk heterojunction organic solar cells requires a morphology that delivers electron and hole percolation pathways for optimized transport, plus sufficient donor:acceptor contact area for near unity charge transfer state formation. This is a significant structural challenge, particularly in semiconducting polymer:fullerene systems. This balancing act in the model high efficiency PTB7:PC70BM blend is studied by tuning the donor:acceptor ratio, with a view to understanding the recombination loss mechanisms above and below the fullerene transport percolation threshold. The internal quantum efficiency is found to be strongly correlated to the slower carrier mobility in agreement with other recent studies. Furthermore, second-order recombination losses dominate the shape of the current density-voltage curve in efficient blend combinations, where the fullerene phase is percolated. However, below the charge transport percolation threshold, there is an electric-field dependence of first-order losses, which includes electric-field-dependent photogeneration. In the intermediate regime, the fill factor appears to be limited by both first- and second-order losses. These findings provide additional basic understanding of the interplay between the bulk heterojunction morphology and the order of recombination in organic solar cells. They also shed light on the limitations of widely used transport models below the percolation threshold.
In order to replace bio-macromolecules by stable synthetic materials in separation techniques and bioanalysis biomimetic receptors and catalysts have been developed: Functional monomers are polymerized together with the target analyte and after template removal cavities are formed in the "molecularly imprinted polymer" (MIP) which resemble the active sites of antibodies and enzymes. Starting almost 80 years ago, around 1,100 papers on MIPs were published in 2016. Electropolymerization allows to deposit MIPs directly on voltammetric electrodes or chips for quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). For the readout of MIPs for drugs amperometry, differential pulse voltammetry (DPV) and impedance spectroscopy (EIS) offer higher sensitivity as compared with QCM or SPR. Application of simple electrochemical devices allows both the reproducible preparation of MIP sensors, but also the sensitive signal generation. Electrochemical MIP-sensors for the whole arsenal of drugs, e.g. the most frequently used analgesics, antibiotics and anticancer drugs have been presented in literature and tested under laboratory conditions. These biomimetic sensors typically have measuring ranges covering the lower nano-up to millimolar concentration range and they are stable under extreme pH and in organic solvents like nonaqueous extracts.
The first molecularly imprinted polymer (MIP) for the recognition of the copper-enzyme laccase was successfully prepared by electropolymerizing scopoletin in the presence of alkaline-inactivated enzyme. Laccase-MIP and the control polymer without laccase (nonimprinted polymer, NIP) were characterized by voltammetry using the redox marker ferricyanide. After electropolymerization, the signals for ferricyanide for both the MIP and the NIP were almost completely suppressed and increased after removal of the target from the polymer layer. Rebinding of both inactivated and active laccase decreased the ferricyanide peak currents to almost equal extent. The relative decrease of signal suppression approached saturation above 10 nM. Furthermore, the surface activity of rebound laccase toward the oxidation of catechol was investigated. The surface activity approached saturation above 10 nM, a value close to the value of the measurements with ferricyanide. Interaction of NIP with laccase brought about a six times smaller signal of catechol oxidation.
Die empirische Studie untersucht, inwieweit die gesellschaftliche Mehrsprachigkeit in Berlin in den verschiedenen Beschilderungstypen der Berliner Krankenhäuser vertreten ist. Damit fügt sich die Arbeit thematisch in die Untersuchung von "Sprachlandschaften" ein, einem neu entstehenden soziolinguistisch orientierten Forschungsfeld, das Zusammenhänge zwischen sozialer Mehrsprachigkeit und ihrer öffentlichen visuellen Repräsentation untersucht und aufdeckt. Welche Sprachen sind in welchen Diskurstypen in Berliner Krankenhäusern sichtbar? Wie entwickelt sich die Entscheidungspolitik, auf deren Grundlage Mehrsprachigkeit in Krankenhäusern sichtbar wird? Für die Befragung wurde jedes Krankenhaus in jedem der zwölf Berliner Bezirke besucht und die Ergebnisse durch Bilddateien dokumentiert. Das Ergebnis dieser Studie ist ein umfassendes Korpus.
Phytochemical investigation of the CH2Cl2/MeOH (1:1) extract of the roots of Lannea rivae (Chiov) Sacleux (Anacardiaceae) led to the isolation of a new alkenyl cyclohexenone derivative: (4R,6S)-4,6-dihydroxy-6-((Z)-nonadec-14′-en-1-yl)cyclohex-2-en-1-one (1), and a new alkenyl cyclohexanol derivative: (2S*,4R*,5S*)-2,4,5-trihydroxy-2-((Z)-nonadec-14′-en-1-yl)cyclohexanone (2) along with four known compounds, namely epicatechin gallate, taraxerol, taraxerone and β-sitosterol; while the stem bark afforded two known compounds, daucosterol and lupeol. Similar investigation of the roots of Lannea schweinfurthii (Engl.) Engl. led to the isolation of four known compounds: 3-((E)-nonadec-16′-enyl)phenol, 1-((E)-heptadec-14′-enyl)cyclohex-4-ene-1,3-diol, catechin, and 1-((E)-pentadec-12′-enyl)cyclohex-4-ene-1,3-diol. The structures of the isolated compounds were determined by NMR spectroscopy and mass spectrometry. The absolute configuration of compound 1 was established by quantum chemical ECD calculations. In an antibacterial activity assay using the microbroth kinetic method, compound 1 showed moderate activity against Escherichia coli while compound 2 exhibited moderate activity against Staphylococcus aureus. Compound 1 also showed moderate activity against E. coli using the disc diffusion method. The roots extract of L. rivae was notably cytotoxic against both the DU-145 prostate cancer cell line and the Vero mammalian cell line (CC50 = 5.24 and 5.20 μg/mL, respectively). Compound 1 was also strongly cytotoxic against the DU-145 cell line (CC50 = 0.55 μg/mL) but showed no observable cytotoxicity (CC50 > 100 μg/mL) against the Vero cell line. The roots extract of L. rivae and L. schweinfurthii, epicatechin gallate as well as compound 1 exhibited inhibition of carageenan-induced inflammation.
QuestionDisturbed areas offer great opportunities for restoring native biodiversity, but they are also prone to invasion by alien plants. Following the limiting similarity hypothesis, we address the question of whether or not similarity of plant functional traits helps developing seed mixtures of native communities with high resistance to invasive species at an early stage of restoration. LocationCentre of Greenhouses and Laboratories Durnast, Technische Universitat Munchen, Freising, Germany. MethodsUsing a system of linear equations, we designed native communities maximizing the similarity between the native and two invasive species according to ten functional traits. We used native grassland plants, two invasive alien species that are often problematic in disturbed areas (i.e., Ambrosia artemisiifolia and Solidago gigantea) and trait information obtained from databases. The two communities were then tested for resistance against establishment of the two invaders separately in a greenhouse experiment. We measured height of the invasive species and above-ground biomass, along with leaf area index, 4 and 8months after sowing respectively. ResultsBoth invasive species were successfully reduced by the native community designed to suppress S. gigantea dominated by small-seeded species. These results could be considered as partial support for the limiting similarity hypothesis. However, given the success of this mixture against both invasive species, suppression was better explained by a seed density effect resulting from the smaller seed mass of the native species included in this mixture. Further, the dominance of a fast-developing competitive species could also contribute to its success. ConclusionsThere was no unequivocal support for the limiting similarity hypothesis in terms of the traits selected. Instead we found that increasing seeding density of native species and selecting species with a fast vegetative development is an effective way to suppress invasive plants during early stages of restoration. If limiting similarity is used to design communities for restoration, early life-history traits should be taken into account.
Imaging CF3I conical intersection and photodissociation dynamics with ultrafast electron diffraction
(2018)
Conical intersections play a critical role in excited-state dynamics of polyatomic molecules because they govern the reaction pathways of many nonadiabatic processes. However, ultrafast probes have lacked sufficient spatial resolution to image wave-packet trajectories through these intersections directly. Here, we present the simultaneous experimental characterization of one-photon and two-photon excitation channels in isolated CF3I molecules using ultrafast gas-phase electron diffraction. In the two-photon channel, we have mapped out the real-space trajectories of a coherent nuclear wave packet, which bifurcates onto two potential energy surfaces when passing through a conical intersection. In the one-photon channel, we have resolved excitation of both the umbrella and the breathing vibrational modes in the CF3 fragment in multiple nuclear dimensions. These findings benchmark and validate ab initio nonadiabatic dynamics calculations.
Recently, we proposed a small molecular inducing ligand strategy to assemble proteins into highly-ordered structures via dual non-covalent interactions, i.e. carbohydrate-protein interaction and dimerization of Rhodamine B. Using this approach, artificial protein microtubules were successfully constructed. In this study, we find that these microtubules exhibit a perfect CO2 responsiveness; assembly and disassembly of these microtubules were nicely controlled by the alternative passage of CO2 and N-2. Upon the injection of CO2, a negative net-charged SBA turns into a neutral or positive net-charged SBA, which elongated, to some extent, the effective distance between SBA and Rhodamine B, resulting in the disassociation of the Rhodamine B dimer. Further experimental and simulation results reveal that the CO2-responsive mechanism differs from that of solubility change of the previously reported CO2-responsive synthetic materials.
Polymeric materials possessing specific features like programmability, high deformability, and easy processability are highly desirable for creating modern actuating systems. In this study, thermoplastic shape-memory polymer actuators obtained by combining crystallizable poly(epsilon-caprolactone) (PCL) and poly(3S-isobutylmorpholin-2,5-dione) (PIBMD) segments in multiblock copolymers are described. We designed these materials according to our hypothesis that the confinement of glassy PIBMD domains present at the upper actuation temperature contribute to the stability of the actuator skeleton, especially at large programming strains. The copolymers have a phase-segregated morphology, indicated by the well-separated melting and glass transition temperatures for PIBMD and PCL, but possess a partially overlapping T-m of PCL and T-g of PIBMD in the temperature interval from 40 to 60 degrees C. Crystalline PIBMD hard domains act as strong physical netpoints in the PIBMD-PCL bulk material enabling high deformability (up to 2000%) and good elastic recoverability (up to 80% at 50 degrees C above T-m,T-PCL). In the programmed thermoplastic actuators a high content of crystallizable PCL actuation domains ensures pronounced thermoreversible shape changes upon repetitive cooling and heating. The programmed actuator skeleton, composed of PCL crystals present at the upper actuation temperature T-high and the remaining glassy PIBMD domains, enabled oriented crystallization upon cooling. The actuation performance of PIBMD-PCL could be tailored by balancing the interplay between actuation and skeleton, but also by varying the quantity of crystalline PIBMD hard domains via the copolymer composition, the applied programming strain, and the choice of T-high. The actuator with 17 mol% PIBMD showed the highest reversible elongation of 11.4% when programmed to a strain of 900% at 50 degrees C. It is anticipated that the presented thermoplastic actuator materials can be applied as modern compression textiles.
The variation of the molecular architecture of multiblock copolymers has enabled the introduction of functional behaviour and the control of key mechanical properties. In the current study, we explore the synergistic relationship of two structural components in a shape-memory material formed of a multiblock copolymer with crystallizable poly(epsilon-caprolactone) and crystallizable polyfoligo(3S-iso-butylmorpholine-2,5-dione) segments (PCL-PIBMD). The thermal and structural properties of PCL-PIBMD films were compared with PCI.-PU and PMMD-PU investigated by means of DSC, SAXS and WARS measurements. The shape-memory properties were quantified by cyclic, thermomechanical tensile tests, where deformation strains up to 900% were applied for programming PCL-PIBMD films at 50 degrees C. Toluene vapor treatment experiments demonstrated that the temporary shape was fixed mainly by glassy PIBMD domains at strains lower than 600% with the PCL contribution to fixation increasing to 42 +/- 2% at programming strains of 900% This study into the shape-memory mechanism of PCL-PIBMD provides insight into the structure function relation in multiblock copolymers with both crystallizable and glassy switching segments.
Understanding the variability of the ionosphere is important for the prediction of space weather and climate. Recent studies have shown that forcing from the lower atmosphere plays a significant role for the short-term (day-to-day) variability of the low-latitude ionosphere. The present study aims to assess the importance of atmospheric forcing for the variability of the daytime equatorial ionospheric electric field on the interannual (year-to-year) time scale. Magnetic field measurements from Huancayo (12.05 degrees S, 75.33 degrees W) are used to augment the equatorial vertical plasma drift velocity (V-Z) measurements from the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere radar during 2001-2016. V-Z can be regarded as a measure of the zonal electric field. After removing the seasonal variation of similar to 10m/s, midday values of V-Z show an interannual variation of similar to 2m/s with an oscillation period of 2-3years. No evidence of solar cycle influence is found. The Ground-to-topside Atmosphere-Ionosphere model for Aeronomy, which takes into account realistic atmospheric variability below 30km, reproduces the pattern of the observed interannual variation without having to include variable forcing from the magnetosphere. The results indicate that lower atmospheric forcing plays a dominant role for the observed interannual variability of V-Z at 1200 local time.
The equatorial electrojet is an enhanced eastward current in the dayside E region ionosphere flowing along the magnetic equator. The equatorial electrojet is highly variable as it is subject to various forcing mechanisms including atmospheric waves from the lower layers of the atmosphere. There are occasionally times when the intensity of the equatorial electrojet at a fixed longitude shows an oscillatory variation with a period of approximately 6days. We present case studies of such events based on the equatorial electrojet measurements from the CHAMP and Swarm satellites. The spatial and temporal variability of the equatorial electrojet intensity during these events reveals characteristics of a westward propagating wave with zonal wavenumber 1, consistent with the effect of the quasi-6-day planetary wave. Analyses of the geopotential height data from the Aura satellite confirm the presence of the quasi-6-day planetary wave in the lower thermosphere during the events. The amplitude of the quasi-6-day variation in the equatorial electrojet intensity depends on longitude, but no systematic longitudinal dependence is found for different events. During the event of August 2010, quasi-6-day variations are also observed by ground-based magnetometers and a radar in the Peruvian sector. The effect of the quasi-6-day wave accounts for up to +/- 5.9m/s in the equatorial vertical plasma velocity at noon, which is much larger than previously predicted by a numerical model. These results suggest that the quasi-6-day planetary wave is an important source of short-term variability in the equatorial ionosphere.
Coupling land-use change and hydrologic models for quantification of catchment ecosystem services
(2018)
Representation of land-use and hydrologic interactions in respective models has traditionally been problematic. The use of static land-use in most hydrologic models or that of the use of simple hydrologic proxies in land-use change models call for more integrated approaches. The objective of this study is to assess whether dynamic feedback between land-use change and hydrology can (1) improve model performances, and/or (2) produce a more realistic quantification of ecosystem services. To test this, we coupled a land-use change model and a hydrologic mode. First, the land-use change and the hydrologic models were separately developed and calibrated. Then, the two models were dynamically coupled to exchange data at yearly time-steps. The approach is applied to a catchment in South Africa. Performance of coupled models when compared to the uncoupled models were marginal, but the coupled models excelled at the quantification of catchment ecosystem services more robustly.
Hypothesis: An effective way for fixating vesicle structures is the insertion of monomers and cross-linking agents into their bilayer, and their subsequent polymerization can lead to the formation of polymeric nanocapsules. Particularly attractive here are vesicle systems that form spontaneously well-defined small vesicles, as obtaining such small nanocapsules with sizes below 100 nm is still challenging. Experiments: A spontaneously forming well-defined vesicle system composed of the surfactants TDMAO (tetradecyldimethylamine oxide), Pluronic L35, and LiPFOS (lithium perfluorooctylsulfonate) mixture was used as template for fixation by polymerization. Therefore, styrene monomer was incorporated into the vesicle bilayer and ultimately these structures were fixated by UV induced radical polymerization. Structural alteration of the vesicles upon loading with monomer and the cross-linker as well as the effect of subsequent polymerization in the membrane were investigated in detail by turbidity measurements, dynamic and static light scattering, (DLS, SLS), and small angle neutron scattering (SANS). Findings: The analysis showed the changes on vesicle structures due to the monomer loading, and that these structures can become permanently fixed by the polymerization process. The potential of this approach to produce well-defined nanocapsules starting from a self-assembled system and following polymerization is critically evaluated. (C) 2018 Elsevier Inc. All rights reserved.
In this paper two groups supporting different views on the mechanism of light induced polymer deformation argue about the respective underlying theoretical conceptions, in order to bring this interesting debate to the attention of the scientific community. The group of Prof. Nicolae Hurduc supports the model claiming that the cyclic isomerization of azobenzenes may cause an athermal transition of the glassy azobenzene containing polymer into a fluid state, the so-called photo-fluidization concept. This concept is quite convenient for an intuitive understanding of the deformation process as an anisotropic flow of the polymer material. The group of Prof. Svetlana Santer supports the re-orientational model where the mass-transport of the polymer material accomplished during polymer deformation is stated to be generated by the light-induced re-orientation of the azobenzene side chains and as a consequence of the polymer backbone that in turn results in local mechanical stress, which is enough to irreversibly deform an azobenzene containing material even in the glassy state. For the debate we chose three polymers differing in the glass transition temperature, 32 °C, 87 °C and 95 °C, representing extreme cases of flexible and rigid materials. Polymer film deformation occurring during irradiation with different interference patterns is recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the kinetics of film deformation. We also demonstrated the unique behaviour of azobenzene containing polymeric films to switch the topography in situ and reversibly by changing the irradiation conditions. We discuss the results of reversible deformation of three polymers induced by irradiation with intensity (IIP) and polarization (PIP) interference patterns, and the light of homogeneous intensity in terms of two approaches: the re-orientational and the photo-fluidization concepts. Both agree in that the formation of opto-mechanically induced stresses is a necessary prerequisite for the process of deformation. Using this argument, the deformation process can be characterized either as a flow or mass transport.
We discuss recent investigations of the interaction of polyelectrolytes with proteins. In particular, we review our recent studies on the interaction of simple proteins such as human serum albumin (HSA) and lysozyme with linear polyelectrolytes, charged dendrimers, charged networks, and polyelectrolyte brushes. In all cases discussed here, we combined experimental work with molecular dynamics (MD) simulations and mean-field theories. In particular, isothermal titration calorimetry (ITC) has been employed to obtain the respective binding constants K-b and the Gibbs free energy of binding. MD simulations with explicit counterions but implicit water demonstrate that counterion release is the main driving force for the binding of proteins to strongly charged polyelectrolytes: patches of positive charges located on the surface of the protein become multivalent counterions of the polyelectrolyte, thereby releasing a number of counterions condensed on the polyelectrolyte. The binding Gibbs free energy due to counterion release is predicted to scale with the logarithm of the salt concentration in the system, which is verified by both simulations and experiment. In several cases, namely, for the interaction of proteins with linear polyelectrolytes and highly charged hydrophilic dendrimers, the binding constant could be calculated from simulations to very good approximation. This finding demonstrated that in these cases explicit hydration effects do not contribute to the Gibbs free energy of binding. The Gibbs free energy can also be used to predict the kinetics of protein uptake by microgels for a given system by applying dynamic density functional theory. The entire discussion demonstrates that the direct comparison of theory with experiments can lead to a full understanding of the interaction of proteins with charged polymers. Possible implications for applications, such as drug design, are discussed.
Vibrationally resolved lowest-energy bands of the photoelectron spectra (PES) of adamantane, diamantane, and urotropine were simulated by a time-dependent correlation function approach within the harmonic approximation. Geometries and normal modes for neutral and cationic molecules were obtained from B3LYP hybrid density functional theory (DFT). It is shown that the simulated spectra reproduce the experimentally observed vibrational finestructure (or its absence) quite well. Origins of the finestructure are discussed and related to recurrences of autocorrelation functions and dominant vibrations. Remaining quantitative and qualitative errors of the DFT-derived PES spectra refer to (i) an overall redshift by ∼0.5 eV and (ii) the absence of satellites in the high-energy region of the spectra. The former error is shown to be due to the neglect of many-body corrections to ordinary Kohn-Sham methods, while the latter has been argued to be due to electron-nuclear couplings beyond the Born-Oppenheimer approximation [Gali et al., Nat. Commun. 7, 11327 (2016)].
Vibrationally resolved absorption and emission (fluorescence) spectra of perylene and its N-derivatives in gas phase and in solution (acetonitrile) were simulated using a time-dependent approach based on correlation functions determined by density functional theory. By systematically varying the number and position of N atoms, it is shown that the presence of nitrogen heteroatoms has a negligible effect on the molecular structure and geometric distortions upon electronic transitions, while spectral properties change: in particular the number of N atoms is important while their position is less decisive. Thus, the N-substitution can be used to fine-tune the optical properties of perylene-based molecules.
Time-dependent correlation function based methods to study optical spectroscopy involving electronic transitions can be traced back to the work of Heller and coworkers. This intuitive methodology can be expected to be computationally efficient and is applied in the current work to study the vibronic absorption, emission, and resonance Raman spectra of selected organic molecules. Besides, the "non-standard" application of this approach to photoionization processes is also explored. The application section consists of four chapters as described below.
In Chapter 4, the molar absorptivities and vibronic absorption/emission spectra of perylene and several of its N-substituted derivatives are investigated. By systematically varying the number and position of N atoms, it is shown that the presence of nitrogen heteroatoms has a negligible effect on the molecular structure and geometric distortions upon electronic transitions, while spectral properties are more sensitive: In particular the number of N atoms is important while their position is less decisive. Thus, N-substitution can be used to fine-tune the optical properties of perylene-based molecules.
In Chapter 5, the same methods are applied to study the vibronic absorption/emission and resonance Raman spectra of a newly synthesized donor-acceptor type molecule. The simulated absorption/emission spectra agree fairly well with experimental data, with discrepancies being attributed to solvent effects. Possible modes which may dominate the fine-structure in the vibronic spectra are proposed by analyzing the correlation function with the aid of Raman and resonance Raman spectra.
In the next two chapters, besides the above types of spectra, the methods are extended to study photoelectron spectra of several small diamondoid-related systems (molecules, radicals, and cations). Comparison of the photoelectron spectra with available experimental data suggests that the correlation function based approach can describe ionization processes reasonably well. Some of these systems, cationic species in particular, exhibit somewhat peculiar optical behavior, which presents them as possible candidates for functional devices.
Correlation function based methods in a more general sense can be very versatile. In fact, besides the above radiative processes, formulas for non-radiative processes such as internal conversion have been derived in literature. Further implementation of the available methods is among our next goals.
Fragmentation of endohedral fullerene Ho3N@C-80 in an intense femtosecond near-infrared laser field
(2018)
The fragmentation of gas phase endohedral fullerene, Ho3N@C-80, was investigated using femtosecond near-infrared laser pulses with an ion velocity map imaging spectrometer. We observed that Ho+ abundance associated with carbon cage opening dominates at an intensity of 1.1 x 10(14) W/cm(2). As the intensity increases, the Ho+ yield associated with multifragmentation of the carbon cage exceeds the prominence of Ho+ associated with the gentler carbon cage opening. Moreover, the power law dependence of Ho+ on laser intensity indicates that the transition of the most likely fragmentation mechanisms occurs around 2.0 x 10(14) W/cm(2).
By using 3-year global positioning system (GPS) measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between +/- 5 and +/- 20 degrees magnetic latitude (MLAT) and high latitudes above 60 degrees MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20 degrees, and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.
By using 3-year global positioning system (GPS)measurements from December 2013 to November 2016, we provide in this study a detailed survey on the climatology of the GPS signal loss of Swarm onboard receivers. Our results show that the GPS signal losses prefer to occur at both low latitudes between ±5 and ±20 ◦ magnetic latitude (MLAT) and high latitudes above 60 ◦ MLAT in both hemispheres. These events at all latitudes are observed mainly during equinoxes and December solstice months, while totally absent during June solstice months. At low latitudes the GPS signal losses are caused by the equatorial plasma irregularities shortly after sunset, and at high latitude they are also highly related to the large density gradients associated with ionospheric irregularities. Additionally, the high-latitude events are more often observed in the Southern Hemisphere, occurring mainly at the cusp region and along nightside auroral latitudes. The signal losses mainly happen for those GPS rays with elevation angles less than 20 ◦ , and more commonly occur when the line of sight between GPS and Swarm satellites is aligned with the shell structure of plasma irregularities. Our results also confirm that the capability of the Swarm receiver has been improved after the bandwidth of the phase-locked loop (PLL) widened, but the updates cannot radically avoid the interruption in tracking GPS satellites caused by the ionospheric plasma irregularities. Additionally, after the PLL bandwidth increased larger than 0.5 Hz, some unexpected signal losses are observed even at middle latitudes, which are not related to the ionospheric plasma irregularities. Our results suggest that rather than 1.0 Hz, a PLL bandwidth of 0.5 Hz is a more suitable value for the Swarm receiver.
Transdualism
(2018)
The author introduces the concept of transdualism to critique dualism without relying on a dualistic model of critique, the modus operandi necessary for a critique against sexual dualism and hetero/cisnormativity. Transdualism offers an opportunity to dwell within that operation by staying below (not beyond) the “dualism,” that is, below the logic of either/or. The essay will explore the notion of “transdualism” through the hexagram Tai of the Yi Jing, which is often used in medical contexts to illustrate the body-of-orifices of Huangdi Neijing or the Inner Canon of the Yellow Emperor. The author reads this body-of-orifices, which is primarily represented by its nine major bodily tunnels, with yinyang philosophy as gender/sex indeterminant and shows that the Inner Canon's yinyang body-of-orifices points to something more transgressive, which could unsettle from within the naturalism of gender and sexual dualism and the nature/culture as well as other dualistic divides that have informed contemporary critical rethinking of embodiment. By unpacking the hexagram Tai alongside Inner Canon's body-of-orifices. as well as contemporary feminist, queer, and transgender theorizations of the body and sexuality, this essay aims at rethinking the materio-discursive complexity of the body-of-orifices, which has been either dualistically separated into antagonisms between man and woman, sex and gender, body and discourse, yin and yang; or one-sidedly reduced to a function of “social construction,” knowable only through language—or problematically lumped together in a gender-is-fluid postmodern “both-and,” which supposedly overcomes the metaphysico-theological “either/or.”
The central Andes
(2018)
The Central Andes and the Atacama Desert represent a unique geological, climatic, and magmatic setting on our planet. It is the only place on Earth where subduction of an oceanic plate below an active continental margin has led to an extensive mountain chain and an orogenic plateau that is second in size only to the Tibetan Plateau, which resulted from continental collision. In this article, we introduce the history of the Central Andes and the evolution of its landscape. We also discuss links between tectonic forces, magmatism, and the extreme hyperarid climate of this land that, in turn, has led to rich deposits of precious ores and minerals.
Present-day domestic horses are immensely diverse in their maternally inherited mitochondrial DNA, yet they show very little variation on their paternally inherited Y chromosome. Although it has recently been shown that Y chromosomal diversity in domestic horses was higher at least until the Iron Age, when and why this diversity disappeared remain controversial questions. We genotyped 16 recently discovered Y chromosomal single-nucleotide polymorphisms in 96 ancient Eurasian stallions spanning the early domestication stages (Copper and Bronze Age) to the Middle Ages. Using this Y chromosomal time series, which covers nearly the entire history of horse domestication, we reveal how Y chromosomal diversity changed over time. Our results also show that the lack of multiple stallion lineages in the extant domestic population is caused by neither a founder effect nor random demographic effects but instead is the result of artificial selection-initially during the Iron Age by nomadic people from the Eurasian steppes and later during the Roman period. Moreover, the modern domestic haplotype probably derived from another, already advantageous, haplotype, most likely after the beginning of the domestication. In line with recent findings indicating that the Przewalski and domestic horse lineages remained connected by gene flow after they diverged about 45,000 years ago, we present evidence for Y chromosomal introgression of Przewalski horses into the gene pool of European domestic horses at least until medieval times.
Cobras are among the most widely known venomous snakes, and yet their taxonomy remains incompletely understood, particularly in Africa. Here, we use a combination of mitochondrial and nuclear gene sequences and morphological data to diagnose species limits within the African forest cobra, Naja (Boulengerina) melanoleuca. Mitochondrial DNA sequences reveal deep divergences within this taxon. Congruent patterns of variation in mtDNA, nuclear genes and morphology support the recognition of five separate species, confirming the species status of N. subfulva and N. peroescobari, and revealing two previously unnamed West African species, which are described as new: Naja (Boulengerina) guineensis sp. nov. Broadley, Trape, Chirio, Ineich & Wuster, from the Upper Guinea forest of West Africa, and Naja (Boulengerina) savannula sp. nov. Broadley, Trape, Chirio & Wuster, a banded form from the savanna-forest mosaic of the Guinea and Sudanian savannas of West Africa. The discovery of cryptic diversity in this iconic group highlights our limited understanding of tropical African biodiversity, hindering our ability to conserve it effectively.
Pri ha-Pardes (Früchte des Obstgartens) ist eine Schriftenreihe der Vereinigung für Jüdische Studien e. V., welche in Verbindung mit dem Institut für Jüdische Studien und Religionswissenschaft der Universität Potsdam publiziert wird.
Was haben eine Volkssängerin, eine Malerin, ein Linguist und ein Journalist gemeinsam? Und was ein Haus in der Bronx an der letzten Station des D-trains und ein Festival und Lernort wie der Yiddish Summer Weimar? In diesem Fall ist die Lösung des Rätsels die Liebe zur jiddischen Sprache und Musik. Hier geht es um generationenübergreifenden Jiddischismus in der Familie Beyle Schaechter-Gottesmans, zuhause (im Bronxer Haus), in der näheren Umgebung „Beynbridzhivke“ rund um Bainbridge Avenue sowie Ausstrahlungen in die (auch nichtjüdische) Welt, z. B. zum Yiddish Summer Weimar oder durch den „Yiddish Song of the Week“-Blog.
Die vorliegende Studie stellt Leben und Werk der Jiddischistin, Sängerin, Dichterin, Malerin und Pädagogin Beyle Schaechter-Gottesman vor und untersucht insbesondere die innerfamiliäre Tradierung jiddischer Kultur (von der Mutter, der Volkssängerin, über den Linguistenbruder hin zum Journalisten- und Folkloristensohn) sowie den Einfluss, den die Familie in der jiddischen Welt anerkanntermaßen ausgeübt hat.
Schaechter-Gottesman, in Wien geboren, wuchs in Czernowitz auf, überlebte das Czernowitzer Ghetto, emigrierte 1951 nach New York. Dort hielt sie weiterhin an der jiddischen Sprache und Kultur bewusst fest und wollte diese lebendig halten. Sie fing an, Kindertheaterstücke, Lieder und Gedichte auf Jiddisch zu schreiben und wurde 2005 mit dem National Endowment for the Arts Fellowship ausgezeichnet, welches in den USA als Nobelpreis der traditionellen Künste gilt.
Inwieweit wirkten entscheidende Einflüsse des Jiddischismus auf Schaechter-Gottesman? Aus welchen familiären Traditionen wurden diese gespeist und wie drücken sie sich in ihrem Werk aus? Beyle Schaechter-Gottesman bewahrte traditionelles Liedgut und brachte durch ihre eigenen Lieder einen anderen Wind in die jiddische Musikwelt. Auf welche Art und Weise trägt die aktive Tradierung jiddischer Lieder zum Jiddischismus bei bzw. welche Funktion kann Musik innerhalb des Jiddischismus einnehmen?
Dumortierite was synthesized in piston-cylinder experiments at 2.5-4.0 GPa, 650-700 degrees C in the Al2O3 -B2O3-SiO2-H2O (ABSH) system. Electron-microprobe (EMP) analyses reveal significant boron-excess (up to 0.26 B-[4] per formula unit, pfu) and silicon-deficiency relative to the ideal anhydrous dumortierite stoichiometry Al7BSi3O18 . The EMP data in conjunction with results from single-crystal Raman spectroscopy and powder X-ray diffraction provide evidence that silicon at the tetrahedral site is replaced by excess boron via the substitution Si-[4] <--> B-[4] + H. The Raman spectrum of synthetic dumortierite in the frequency region 2000 4000 cm(-1) comprises eight bands, of which six are located at frequencies below 3400 cm(-1). This points to strong hydrogen bonding, most likely O2-H center dot center dot center dot O7 and O7-H center dot center dot center dot O2, arising from a high number of octahedral vacancies at the All site and substitution of trivalent Al3+ and B3+ for Si4+ at Si1 and Si2 sites, causing decreasing acceptor-donor distances and lower incident valence at the acceptor oxygen. Contrary to the synthetic high-pressure ABSH-dumortierite, magnesiodumortierite from the Dora-Maira Massif, which is assumed to have formed at similar conditions (2.5-3.0 GPa, 700 degrees C), does not show any B-excess. Tourmaline shows an analogous behaviour in that magnesium-rich (e.g., dravitic) tourmaline formed at high pressure shows no or only minor amounts of tetrahedral boron, whereas natural aluminum-rich tourmaline and synthetic olenitic tourmaline formed at high pressures can incorporate significant amounts of tetrahedral boron. Two mechanisms might account for this discrepancy: (i) Structural avoidance of Mg-[6]-(OR3+)-R-[4] configurations in magnesiodumortierite due to charge deficieny at the oxygens O2 and O7 and strong local distortion of M1 due to decreased O2-O7 bond length, and/or (ii) decreasing fluid mobility of boron in Al-rich systems at high pressures.
This dissertation consists of four self-contained papers that deal with the implications of financial market imperfections and heterogeneity. The analysis mainly relates to the class of incomplete-markets models but covers different research topics.
The first paper deals with the distributional effects of financial integration for developing countries. Based on a simple heterogeneous-agent approach, it is shown that capital owners experience large welfare losses while only workers moderately gain due to higher wages. The large welfare losses for capital owners contrast with the small average welfare gains from representative-agent economies and indicate that a strong opposition against capital market opening has to be expected.
The second paper considers the puzzling observation of capital flows from poor to rich countries and the accompanying changes in domestic economic development. Motivated by the mixed results from the literature, we employ an incomplete-markets model with different types of idiosyncratic risk and borrowing constraints. Based on different scenarios, we analyze under what conditions the presence of financial market imperfections contributes to explain the empirical findings and how the conditions may change with different model assumptions.
The third paper deals with the interplay of incomplete information and financial market imperfections in an incomplete-markets economy. In particular, it analyzes the impact of incomplete information about idiosyncratic income shocks on aggregate saving. The results show that the effect of incomplete information is not only quantitatively substantial but also qualitatively ambiguous and varies with the influence of the income risk and the borrowing constraint.
Finally, the fourth paper analyzes the influence of different types of fiscal rules on the response of key macroeconomic variables to a government spending shock. We find that a strong temporary increase in public debt contributes to stabilizing consumption and leisure in the first periods following the change in government spending, whereas a non-debt-intensive fiscal rule leads to a faster recovery of consumption, leisure, capital and output in later periods. Regarding optimal debt policy, we find that a debt-intensive fiscal rule leads to the largest aggregate welfare benefit and that the individual welfare gain is particularly high for wealth-poor agents.
Aims Anterior lumbar interbody fusion procedures (ALIF) and total disc replacement (TDR) with anterior exposure of the lumbar spine entail a risk of a vascular injury and dysfunction of the sympathetic and parasympathetic nerves due to disturbance of the inferior and superior hypogastric plexus. While retrograde ejaculation is a known complication of the anterior spinal approach in males, post-operative sexual as well as urinary function in females has not yet been thoroughly investigated and was hence the aim of this study. Methods Fifteen female patients documented their sexual and urinary function preoperatively, 3 months and 6 months postoperatively, using the validated questionnaires FSFI (Female Sexual Function Index) and ICIQ (International Consultation of Incontinence Questionnaire). Randomization tests were used to statistically analyze expectation values over time (two-sided, P < 0.05). Results While no statistically significant change in the total FSFI score occurred over time, a significant increase in FSFI desire score was noted between preoperative (2.95 +/- 0.8) and 6 months follow-up (3.51 +/- 0.6, P = 0.02). Urinary continence remained unchanged over time. Conclusion In summary, ALIF and lumbar TDR do not seem to negatively influence sexual and urinary function in females. In contrast, increased sexual desire was noted, likely secondary to post-surgical pain relief.
While the role of and consequences of being a bystander to face-to-face bullying has received some attention in the literature, to date, little is known about the effects of being a bystander to cyberbullying. It is also unknown how empathy might impact the negative consequences associated with being a bystander of cyberbullying. The present study focused on examining the longitudinal association between bystander of cyberbullying depression, and anxiety, and the moderating role of empathy in the relationship between bystander of cyberbullying and subsequent depression and anxiety. There were 1,090 adolescents (M-age = 12.19; 50% female) from the United States included at Time 1, and they completed questionnaires on empathy, cyberbullying roles (bystander, perpetrator, victim), depression, and anxiety. One year later, at Time 2, 1,067 adolescents (M-age = 13.76; 51% female) completed questionnaires on depression and anxiety. Results revealed a positive association between bystander of cyberbullying and depression and anxiety. Further, empathy moderated the positive relationship between bystander of cyberbullying and depression, but not for anxiety. Implications for intervention and prevention programs are discussed.
While the role of and consequences of being a bystander to face-to-face bullying has received some attention in the literature, to date, little is known about the effects of being a bystander to cyberbullying. It is also unknown how empathy might impact the negative consequences associated with being a bystander of cyberbullying. The present study focused on examining the longitudinal association between bystander of cyberbullying depression, and anxiety, and the moderating role of empathy in the relationship between bystander of cyberbullying and subsequent depression and anxiety. There were 1,090 adolescents (M-age = 12.19; 50% female) from the United States included at Time 1, and they completed questionnaires on empathy, cyberbullying roles (bystander, perpetrator, victim), depression, and anxiety. One year later, at Time 2, 1,067 adolescents (M-age = 13.76; 51% female) completed questionnaires on depression and anxiety. Results revealed a positive association between bystander of cyberbullying and depression and anxiety. Further, empathy moderated the positive relationship between bystander of cyberbullying and depression, but not for anxiety. Implications for intervention and prevention programs are discussed.
The purpose of the present study was to examine the moderation of parental mediation in the longitudinal association between being a bystander of cyberbullying and cyberbullying perpetration and cyberbullying victimization. Participants were 1067 7th and 8th graders between 12 and 15 years old (51% female) from six middle schools in predominantly middle-class neighborhoods in the Midwestern United States. Increases in being bystanders of cyberbullying was related positively to restrictive and instructive parental mediation. Restrictive parental mediation was related positively to Time 2 (T2) cyberbullying victimization, while instructive parental mediation was negatively related to T2 cyberbullying perpetration and victimization. Restrictive parental mediation was a moderator in the association between bystanders of cyberbullying and T2 cyberbullying victimization. Increases in restrictive parental mediation strengthened the positive relationship between these variables. In addition, instructive mediation moderated the association between bystanders of cyberbullying and T2 cyberbullying victimization such that increases in this form of parental mediation strategy weakened the association between bystanders of cyberbullying and T2 cyberbullying victimization. The current findings indicate a need for parents to be aware of how they can impact adolescents’ involvement in cyberbullying as bullies and victims. In addition, greater attention should be given to developing parental intervention programs that focus on the role of parents in helping to mitigate adolescents’ likelihood of cyberbullying involvement.