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Die Entstehung einer Legende
(2006)
This paper sheds light on the history of the quotation “I regard the environs of Salzburg, Naples, and Constantinople as the most beautiful on earth”, which is usually attributed to Alexander von Humboldt. The author shows that Humboldt’s alleged praise of Salzburg first appeared around 1870, and thus the quotation cannot be regarded as authentic. As a local legend it was meant to connect permanently the famous name of Humboldt with that of the growing centre of tourism. The circumstances under which the quotation found its way into the literature remain to be investigated; however, it seems clear that this can be seen as a typical example of what Eric Hobsbawm has called „invention of tradition“. Invented traditions – this might comfort the tourist industry of Salzburg – have particularly long lives.
Small-scale variations in mineral chemistry, textures, and platinum group element (PGE) mineralization were investigated in the Lower and Middle Group chromitite layers LG6, LG6a, MG1, MG2, and MG2 II from vertical drill core profiles at the Thaba mine in the northwestern limb of the Bushveld Complex. We present detailed geochemical profiles of chromite composition and chromite crystal size distribution curves to shed light on the processes of chromite accumulation and textural modification as well as mineralization. Multiple samples within each layer were assayed for PGE concentrations, and the respective platinum group mineral association was determined by mineral liberation analysis (MLA). There is strong evidence for postcumulus changes in the chromitites. The crystal size distribution curves suggest that the primary chromite texture was coarsened by a combination of adcumulus growth and textural equilibration, while compaction of the crystal mush played only a minor role. Mineral compositions were also modified by postcumulus processes, but because of the very high modal amount of chromite and its local preservation in orthopyroxene oikocrysts, that phase retained much primary information. Vertical variations of chromite composition within chromitite layers and from one layer to another do not support the idea of chromite accumulation from crystal-rich slurries or crystal settling from a large magma chamber. Instead, we favor a successive buildup of chromitite layers by repeated injections of relatively thin layers of chromite-saturated magmas, with in situ crystallization occurring at the crystal mush-magma interface. The adcumulus growth of chromite grains to form massive chromitite required addition of Cr to the layers, which we attribute to downward percolation from the overlying magma. The PGE concentrations are elevated in all chromitite layers compared to adjacent silicate rocks and show a systematic increase upward from LG6 (avg 807 ppb Ir + Ru + Rh + Pt + Pd + Au) to MG2 II (avg 2,062 ppb). There are also significant internal variations in all layers, with enrichments at hanging and/or footwalls. The enriched nature of chromitites in PGEs compared to host pyroxenites is a general feature, independent of the layer thickness. The MLA results distinguish two principal groups of PGE mineral associations: the LG6, LG6, and MG1 are dominated by the malanite series, laurite, and PGE sulfarsenides, while the MG2 and MG2 II layers are characterized by laurite and PGE sulfides as well as Pt-Fe-Sn and PGE-Sb-Bi-Pb alloys. Differences in the PGE associations are attributed to postcumulus alteration of the MG2 and MG2 II layer, while the chromitites below, particularly LG6 and LG6a, contain a more pristine association.
We used single-molecule FRET in combination with other biophysical methods and molecular simulations to investigate the effect of temperature on the dimensions of unfolded proteins. With singlemolecule FRET, this question can be addressed even under nearnative conditions, where most molecules are folded, allowing us to probe a wide range of denaturant concentrations and temperatures. We find a compaction of the unfolded state of a small cold shock protein with increasing temperature in both the presence and the absence of denaturant, with good agreement between the results from single-molecule FRET and dynamic light scattering. Although dissociation of denaturant from the polypeptide chain with increasing temperature accounts for part of the compaction, the results indicate an important role for additional temperaturedependent interactions within the unfolded chain. The observation of a collapse of a similar extent in the extremely hydrophilic, intrinsically disordered protein prothymosin suggests that the hydrophobic effect is not the sole source of the underlying interactions. Circular dichroism spectroscopy and replica exchange molecular dynamics simulations in explicit water show changes in secondary structure content with increasing temperature and suggest a contribution of intramolecular hydrogen bonding to unfolded state collapse.
We have developed a microfluidic mixer optimized for rapid measurements of protein folding kinetics using synchrotron radiation circular dichroism (SRCD) spectroscopy. The combination of fabrication in fused silica and synchrotron radiation allows measurements at wavelengths below 220 nm, the typical limit of commercial instrumentation. At these wavelengths, the discrimination between the different types of protein secondary structure increases sharply. The device was optimized for rapid mixing at moderate sample consumption by employing a serpentine channel design, resulting in a dead time of less than 200 ;s. Here, we discuss the design and fabrication of the mixer and quantify the mixing efficiency using wide-field and confocal epi-fluorescence microscopy. We demonstrate the performance of the device in SRCD measurements of the folding kinetics of cytochrome c, a small, fast-folding protein. Our results show that the combination of SRCD with microfluidic mixing opens new possibilities for investigating rapid conformational changes in biological macromolecules that have previously been inaccessible.
In this work, a closure experiment for tropospheric aerosol is presented. Aerosol size distributions and single scattering albedo from remote sensing data are compared to those measured in-situ. An aerosol pollution event on 4 April 2009 was observed by ground based and airborne lidar and photometer in and around Ny-Alesund, Spitsbergen, as well as by DMPS, nephelometer and particle soot absorption photometer at the nearby Zeppelin Mountain Research Station.
The presented measurements were conducted in an area of 40 x 20 km around Ny-Alesund as part of the 2009 Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project (PAMARCMiP). Aerosol mainly in the accumulation mode was found in the lower troposphere, however, enhanced backscattering was observed up to the tropopause altitude. A comparison of meteorological data available at different locations reveals a stable multi-layer-structure of the lower troposphere. It is followed by the retrieval of optical and microphysical aerosol parameters. Extinction values have been derived using two different methods, and it was found that extinction (especially in the UV) derived from Raman lidar data significantly surpasses the extinction derived from photometer AOD profiles. Airborne lidar data shows volume depolarization values to be less than 2.5% between 500 m and 2.5 km altitude, hence, particles in this range can be assumed to be of spherical shape. In-situ particle number concentrations measured at the Zeppelin Mountain Research Station at 474 m altitude peak at about 0.18 mu m diameter, which was also found for the microphysical inversion calculations performed at 850 m and 1500 m altitude. Number concentrations depend on the assumed extinction values, and slightly decrease with altitude as well as the effective particle diameter. A low imaginary part in the derived refractive index suggests weakly absorbing aerosols, which is confirmed by low black carbon concentrations, measured at the Zeppelin Mountain as well as on board the Polar 5 aircraft.
The organic market is characterized by remarkable disparities, and confusion persists about which motives drive organic consumption. To understand them, this research introduces the idea that the same consumer motives can exert different and potentially opposite impacts when organic consumption patterns unfold. The proposed multistage theory of differential effects distinguishes a participation stage, when consumers decide whether to purchase organic at all, and an expenditure stage, when consumers decide about how much of their budget to spend on organic products across purchases. An analysis of shopping patterns of approximately 14,000 households confirms the proposed differential influences: Other-oriented motives (care for others and the environment) support participation but impede sustained expenditures. Only self-oriented motives (hedonism) foster both participation and expenditures. The results pinpoint the need to rethink organic consumption as a stage-specific problem, which opens up new perspectives for managers about an old but persistent problem.
- Ulrike Leitner: Aus dem Humboldt-Nachlaß: Juan José de Oteyzas Beschreibung der Pyramiden von Teotihuacán
- Ottmar Ette: Alexander von Humboldt, die Humboldtsche Wissenschaft und ihre Relevanz im Netzzeitalter
- Bernd Kölbel, Martin Sauerwein, Katrin Sauerwein, Steffen Kölbel und Lucie Terken: Alexander von Humboldt und seine geognostischen Studien in Göttingen
- Nicolaas A. Rupke: A Metabiography of Alexander von Humboldt
- Franz-J. Weihrauch: Nachrichten aus Amerika oder wie man in Koblenz von Humboldts Reise nach Amerika erfuhr
- Petra Werner Himmelsblau. Bemerkungen zum Thema „Farben“ in Humboldts Alterswerk Kosmos. Entwurf einer physischen Weltbeschreibung
- Robert Hoffmann: Die Entstehung einer Legende. Alexander von Humboldts angeblicher Ausspruch über Salzburg.
There are two fundamental ways in which consumers can express their concerns and obligations for society through their consumption decisions: They can boycott companies that they deem to be irresponsible or they may deliberately buy from companies that they perceive to act responsibly (‘buycott’). It has been largely ignored that individuals are driven by different motivational mechanisms to join boycotts and buycotts (punishment vs. reward of corporate behaviors), and thus, these mechanisms have disparate implications for the participating individual (e.g., high vs. low subjective costs because of a restriction in consumption habits). This paper fills this void and develops a framework suggesting that the extent to which consumers translate their concerns and obligations for society into a willingness to boycott and/or buycott is bounded by self-interest. Using a unique, representative sample of 1833 German consumers, this study reveals that the effects of environmental concerns and universalism on buycotting are amplified by hedonism, while the effects of social concern on buycotting and boycotting are attenuated by hedonism and simplicity, respectively. These results have far-reaching implications for organizations and policy planners who aim to change corporate behavior.