4,438 research outputs found
Nach dem Deutschstudium in Afrika wird man – was? Eine Überprüfung der Zielsetzungen der Deutschabteilung der Universität Lomé anhand einer Verbleibstudie
This paper reports on an investigation of the value of German Studies in eventual employment of students in this field. The objectives of German Studies in Africa have to include an indication of how inclusion in the curriculum is legitimized. Three approaches towards legitimization have developed since the establishment of German Departments at African Universities, namely (i) German Studies with a view to research and epistemological science, (ii) German in intercultural studies, and (iii)career-oriented German language learning. In this paper the implementation of these approaches will be examined on the basis of the objectives set out by the German Department at the University ofLomé. This will be done by discussing the results of a survey on the professional whereabouts of Togolese German Studies graduates to demonstrate the extent to which the objectives of the various approaches have been met. The paper concludes with a discussion of the implications of the findings for the programmes of the German Department at the University of Lomé.Keywords: legitimization debate, distribution survey, teaching German in Africa, German language and literature studies in AfricaSchlüsselbegriffe: Legitimierungsdebatte, Verbleibstudie, Deutschunterricht in Afrika, Germanistik in Afrik
Improved preparation of 9-octadecenes
Organic synthesis of cis-9 and trans-9 octadecenes from oleyl alcohol and elaidyl alcohol, respectively, by conversion to tosylates followed by lithium aluminum hydride reductio
Coherence properties of infrared thermal emission from heated metallic nanowires
Coherence properties of the infrared thermal radiation from individual heated
nanowires are investigated as function of nanowire dimensions. Interfering the
thermally induced radiation from a heated nanowire with its image in a nearby
moveable mirror, well-defined fringes are observed. From the fringe visibility,
the coherence length of the thermal emission radiation from the narrowest
nanowires was estimated to be at least 20 um which is much larger than expected
from a classical blackbody radiator. A significant increase in coherence and
emission efficiency is observed for smaller nanowires.Comment: 4 pages,figures include
The Origins of a Rich Absorption Line Complex in a Quasar at Redshift 3.45
We discuss the nature and origin of a rich complex of narrow absorption lines
in the quasar J102325.31+514251.0 at redshift 3.447. We measure nine C
IV(\lambda1548,1551) absorption line systems with velocities from -1400 to
-6200 km/s, and full widths at half minimum ranging from 16 to 350 km/s. We
also detect other absorption lines in these systems, including H I, C III, N V,
O VI, and Si IV. Lower ionisation lines are not present, indicating a generally
high degree of ionisation in all nine systems. The total hydrogen column
densities range from <=10^{17.2} to 10^{19.1}cm^{-2}. We examine several
diagnostics to estimate more directly the location and origin of each absorber.
Four of the systems can be attributed to a quasar-driven outflow based on line
profiles that are smooth and broad compared to thermal line widths. Several
systems also have other indicators of a quasar outflow origin, including
partial covering. Altogether there is direct evidence for 6 of the 9 systems
forming in a quasar outflow. Consistent with a near-quasar origin, eight of the
systems have metallicity values or lower limits in the range Z >= 1-8 Z_{sun}.
The lowest velocity system, which has an ambiguous location, also has the
lowest metallicity, Z <= 0.3 Z_{sun}, and might form in a non-outflow
environment farther from the quasar. Overall, however, this complex of narrow
absorption lines can be identified with a highly structured, multi-component
outflow from the quasar. The high metallicities are similar to those derived
for other quasars at similar redshifts and luminosities, and are consistent
with evolution scenarios wherein quasars appear after the main episodes of star
formation and metal enrichment in the host galaxies.Comment: 16 pages, 12 figures, Accepted to MNRAS, July 201
Optimising Boltzmann codes for the Planck era
High precision measurements of the Cosmic Microwave Background (CMB)
anisotropies, as can be expected from the Planck satellite, will require
high-accuracy theoretical predictions as well. One possible source of
theoretical uncertainty is the numerical error in the output of the Boltzmann
codes used to calculate angular power spectra. In this work, we carry out an
extensive study of the numerical accuracy of the public Boltzmann code CAMB,
and identify a set of parameters which determine the error of its output. We
show that at the current default settings, the cosmological parameters
extracted from data of future experiments like Planck can be biased by several
tenths of a standard deviation for the six parameters of the standard
Lambda-CDM model, and potentially more seriously for extended models. We
perform an optimisation procedure that leads the code to achieve sufficient
precision while at the same time keeping the computation time within reasonable
limits. Our conclusion is that the contribution of numerical errors to the
theoretical uncertainty of model predictions is well under control -- the main
challenges for more accurate calculations of CMB spectra will be of an
astrophysical nature instead.Comment: 13 pages, 4 figure
Important Prospect: Workshop on Botanical Research and Management in GalĂ pagos, to be Held at the Charles Darwin Research Station, Santa Cruz, GalĂ pagos, Ecuador, 12-18 April 1987
Axions and saxions from the primordial supersymmetric plasma and extra radiation signatures
We calculate the rate for thermal production of axions and saxions via
scattering of quarks, gluons, squarks, and gluinos in the primordial
supersymmetric plasma. Systematic field theoretical methods such as hard
thermal loop resummation are applied to obtain a finite result in a
gauge-invariant way that is consistent to leading order in the strong gauge
coupling. We calculate the thermally produced yield and the decoupling
temperature for both axions and saxions. For the generic case in which saxion
decays into axions are possible, the emitted axions can constitute extra
radiation already prior to big bang nucleosynthesis and well thereafter. We
update associated limits imposed by recent studies of the primordial helium-4
abundance and by precision cosmology of the cosmic microwave background and
large scale structure. We show that the trend towards extra radiation seen in
those studies can be explained by late decays of thermal saxions into axions
and that upcoming Planck results will probe supersymmetric axion models with
unprecedented sensitivity.Comment: 16 pages, 7 figures; v2: references added, minor clarifying
additions, matches published versio
New One-Pot Methodologies for the Modification or Synthesis of Alkaloid Scaffolds
There are several avenues by which promising bioactive natural products can be produced in sufficient quantities to enable lead optimization and medicinal chemistry studies. The total synthesis of natural products is an important, but sometimes difficult, approach and requires the development of innovative synthetic methodologies to simplify the synthesis of complex molecules. Various classes of natural product alkaloids are both common and widely distributed in plants, bacteria, fungi, insects and marine organisms. This mini-review will discuss the scope, mechanistic insights and enantioselectivity aspects of selected examples of recently developed one-pot methods that have been published in 2009 for the synthesis of substituted piperidines, quinolizidines, pyrrolidines, hexahydropyrrolizines, octahydroindolizines and γ-lactams. In addition, progress on the synthesis of β-carboline (manzamine) alkaloids will also be discussed
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