166 research outputs found
Cicero: Agrarian Speeches. Introduction, text, translation and commentary by Gesine Manuwald. Oxford University Press, Oxford 2018.
Rezension zu: Cicero’s De Provinciis Consularibus Oratio. Introduction and commentary by Luca Grillo
Rezension zu: Matthias Gelzer, Cicero. Ein biographischer Versuch, 2., erw. Aufl. mit einer forschungsgeschichtlichen Einleitung und einer Ergänzungsbibliographie von Werner Riess
The impact of vegetation on fractionation of rare earth elements(REE) during water–rock interaction
Previous studies on waters of a streamlet in the Vosges mountains (eastern France) have shown that Sr and rare earth elements (REE) principally originate from apatite dissolution during weathering. However, stream water REE patterns normalized to apatite are still depleted in light REE (LREE, La–Sm) pointing to the presence of an additional LREE depleting process. Speciation calculations indicate that complexation cannot explain this additional LREE depletion. In contrast, vegetation samples are strongly enriched in LREE compared to water and their Sr and Nd isotopic compositions are comparable with those of apatite and waters. Thus, the preferential LREE uptake by the plants at the root–water–soil (apatite) interface might lead to an additional LREE depletion of the waters in the forested catchment. Mass balance calculations indicate that the yearly LREE uptake by vegetation is comparable with the LREE export by the streamlet and, therefore, might be an important factor controlling the LREE depletion in river waters
Leading in Switzerland and Poland : a case study of leadership practices in financial services
Leading across national borders is a challenge, partly due to the cultural differences among employees in different locations. We investigate this dynamic for employees of a Swiss financial services company located in Switzerland and in Poland by surveying employees about their leadership expectations and experiences, as well as about their cultural values. We find that the leadership expectations of employees in these two locations do not differ significantly. However, their experience does, indicating the opportunity for further development of local Polish management practices and leadership behavior, and underlying the importance of local leadership development. In addition, we find that a few cultural dimensions have a significant impact on leadership expectations in both countries, indicating the opportunity to further refine situational leadership behavior throughout the organization independently of location. While organizations spanning across Western and Central European locations need to deal with significant differences in cultural and leadership expectation, our results suggest that they can effectively align leadership practices and thus mitigate the practical challenges arising from these differences
Continuous bunch-by-bunch spectroscopic investigation of the micro-bunching instability
Electron accelerators and synchrotrons can be operated to provide short
emission pulses due to longitudinally compressed or sub-structured electron
bunches. Above a threshold current, the high charge density leads to the
micro-bunching instability and the formation of sub-structures on the bunch
shape. These time-varying sub-structures on bunches of picoseconds-long
duration lead to bursts of coherent synchrotron radiation in the terahertz
frequency range. Therefore, the spectral information in this range contains
valuable information about the bunch length, shape and sub-structures. Based on
the KAPTURE readout system, a 4-channel single-shot THz spectrometer capable of
recording 500 million spectra per second and streaming readout is presented.
First measurements of time-resolved spectra are compared to simulation results
of the Inovesa Vlasov-Fokker-Planck solver. The presented results lead to a
better understanding of the bursting dynamics especially above the
micro-bunching instability threshold.Comment: 12 pages, 11 figure
Fast Mapping of Terahertz Bursting Thresholds and Characteristics at Synchrotron Light Sources
Dedicated optics with extremely short electron bunches enable synchrotron
light sources to generate intense coherent THz radiation. The high degree of
spatial compression in this so-called low-alpha optics entails a complex
longitudinal dynamics of the electron bunches, which can be probed studying the
fluctuations in the emitted terahertz radiation caused by the micro-bunching
instability ("bursting"). This article presents a "quasi-instantaneous" method
for measuring the bursting characteristics by simultaneously collecting and
evaluating the information from all bunches in a multi-bunch fill, reducing the
measurement time from hours to seconds. This speed-up allows systematic studies
of the bursting characteristics for various accelerator settings within a
single fill of the machine, enabling a comprehensive comparison of the measured
bursting thresholds with theoretical predictions by the bunched-beam theory.
This paper introduces the method and presents first results obtained at the
ANKA synchrotron radiation facility.Comment: 7 pages, 7 figures, to be published in Physical Review Accelerators
and Beam
Simultaneous Detection of Longitudinal and Transverse Bunch Signals at a Storage Ring
To understand and control the dynamics in the longitudinal phase space,
time-resolved measurements of different bunch parameters are required. For a
reconstruction of this phase space, the detector systems have to be
synchronized. This reconstruction can be used e.g. for studies of the
micro-bunching instability. It occurs if the interaction of the bunch with its
own radiation leads to the formation of sub-structures on the longitudinal
bunch profile. These sub-structures can grow rapidly -- leading to a
sawtooth-like behaviour of the bunch. At KARA, we use a fast-gated intensified
camera for energy spread studies, Schottky diodes for coherent synchrotron
radiation studies as well as electro-optical spectral decoding for longitudinal
bunch profile measurements. For a synchronization, a hardware synchronization
scheme is used which compensates for eventual hardware delays. In this paper,
the different experimental setups and their synchronization are discussed and
first results of synchronous measurements are presented
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