1,642 research outputs found
Reactivity of pi-complexes of Ti, V, and Nb towards dithioacetic acid: Synthesis and structure of novel metal sulfur-containing complexes
In order to use sulfur-containing resources economically and with minimal environmental damage, it is important to understand the desulfurization processes. Hydrodesulfurization, for example, is carried out on the surface of a heterogeneous metal sulfide catalyst. Studies of simple, soluble inorganic systems provide information regarding the structure and reactivity of sulfur-containing compounds with metal complexes. Further, consistent with recent trends in materials chemistry, many model compounds warrant further study as catalyst precursors. The reactivity of low-valent organometallic sandwich pi-complexes toward dithiocarboxylic acids is described. For example, treatment of bisbenzene vanadium with CH3CSSH affords a divanadium tetrakis(dithioacetate) complex. The crystallographically determined V-V bond distance, 2.800(2), is nearly the same as the V-V bond distance in a V(mu-nu squared-S2)2V' unit in the mineral patonite (VS4)n. The stability of the V2S4 core in the dimer is demonstrated by evidence of V2S4(+) in the mass spectrum (70 eV, solid probe) of the vanadium dimer. Several other systems relevant to HDS catalysis are also discussed
Voneinander Lernen: Ein Handbuch für Sprachlehrerverbände
The publication is aimed at those involved in the running of language teacher associations at international, national, regional and local levels. This may include paid employees or, more frequently, volunteers. It provides guidance on the effective running and networking of associations. It encourages language teacher associations to collaborate in order to support teachers more effectively, and to contribute to improvements in the quality of language teaching. It enables language teachers across the world to share their own ideas, to be involved in research, and to learn about the cutting-edge work of the ECML and its European projects
Learning from each other: A handbook for language teacher associations
The publication is aimed at those involved in the running of language teacher associations at international, national, regional and local levels. This may include paid employees or, more frequently, volunteers. It provides guidance on the effective running and networking of associations. It encourages language teacher associations to collaborate in order to support teachers more effectively, and to contribute to improvements in the quality of language teaching. It enables language teachers across the world to share their own ideas, to be involved in research, and to learn about the cutting-edge work of the ECML and its European project
Apprendre les uns des autres: Manuel pour les associations de professeurs de langues
The publication is aimed at those involved in the running of language teacher associations at international, national, regional and local levels. This may include paid employees or, more frequently, volunteers. It provides guidance on the effective running and networking of associations. It encourages language teacher associations to collaborate in order to support teachers more effectively, and to contribute to improvements in the quality of language teaching. It enables language teachers across the world to share their own ideas, to be involved in research, and to learn about the cutting-edge work of the ECML and its European project
Genetic Distance and Hybridization of Black Ducks and Mallards: A Morph of a Different Color?
Continuity of the four-point function of massive -theory above threshold
In this paper we prove that the four-point function of massive
\vp_4^4-theory is continuous as a function of its independent external
momenta when posing the renormalization condition for the (physical) mass
on-shell. The proof is based on integral representations derived inductively
from the perturbative flow equations of the renormalization group. It closes a
longstanding loophole in rigorous renormalization theory in so far as it shows
the feasibility of a physical definition of the renormalized coupling.Comment: 23 pages; to appear in Rev. Math. Physics few corrections, two
explanatory paragraphs adde
Supersymmetric Yang-Mills-Chern-Simons theory
We prove that three-dimensional N=1 supersymmetric Yang-Mills-Chern-Simons
theory is finite to all loops. This leaves open the possibility that different
regularization methods give different finite effective actions. We show that
for this model dimensional regularization and regularization by dimensional
reduction yield the same effective action.Comment: 6 pages, 1 figure, latex, espcrc2. Contribution to the Proceedings of
the 30th Ahrenshoop Symposium on the Theory of Elementary Particles, edited
by D. Lust, H.-J. Otto and G. Weigt, to appear in Nuclear Physics B,
Proceedings Supplemen
Integration-by-parts identities in FDR
Four-dimensional renormalized (FDR) integrals play an increasingly important
role in perturbative loop calculations. Thanks to them, loop computations can
be performed directly in four dimensions and with no ultraviolet (UV)
counterterms. In this paper I prove that integration-by-parts (IBP) identities
can be used to find relations among multi-loop FDR integrals. Since algorithms
based on IBP are widely applied beyond one loop, this result represents a
decisive step forward towards the use of FDR in multi-loop calculations.Comment: 13 page
Counting statistics of collective photon transmissions
We theoretically study cooperative effects in the steady-state transmission
of photons through a medium of radiators. Using methods from quantum
transport, we find a cross-over in scaling from to in the current and
even higher powers of in the higher cumulants of the photon counting
statistics as a function of the tunable source occupation. The effect should be
observable for atoms confined within a nano-cell with a pumped optical cavity
as photon source.Comment: extended results, 9 pages, 2 figures, to appear in Annals of Physic
Derivation of the Cubic Non-linear Schr\"odinger Equation from Quantum Dynamics of Many-Body Systems
We prove rigorously that the one-particle density matrix of three dimensional
interacting Bose systems with a short-scale repulsive pair interaction
converges to the solution of the cubic non-linear Schr\"odinger equation in a
suitable scaling limit. The result is extended to -particle density matrices
for all positive integer .Comment: 72 pages, 17 figures. Final versio
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