66,493 research outputs found
Large deviations for random walks in a random environment on a strip
We consider a random walk in a random environment (RWRE) on the strip of
finite width . We prove both quenched and
averaged large deviation principles for the position and the hitting times of
the RWRE. Moreover, we prove a variational formula that relates the quenched
and averaged rate functions, thus extending a result of Comets, Gantert, and
Zeitouni for nearest-neighbor RWRE on $\mathbb{Z}
Strict monotonicity properties in one-dimensional excited random walks
We consider one-dimensional excited random walks with finitely many cookies
at each site. There are certain natural monotonicity results that are known for
the excited random walk under some partial orderings of the cookie
environments. We improve these monotonicity results to be strictly monotone
under a partial ordering of cookie environments introduced by Holmes and
Salisbury. While the self-interacting nature of the excited random walk makes a
direct coupling proof difficult, we show that there is a very natural coupling
of the associated branching process from which the monotonicity results follow
Crystal engineering with 2,2':6',2"- terpyridine derivatives and their metal complexes : from simple building blocks to coordination polymers and networks
This thesis concerns the design of ligands for use in the construction of larger
supramolecular systems, with emphasis on the application of 4'-substitured 2,2',6',2''-
terpyridine ligands and their iron(II) and ruthenium(II) complexes in crystal engineering.
The first section considers 4'-hydrazone functionalized 2,2',6',2''-terpyridines and their
dynamic behaviour in solution and structural characteristics in the solid state, with respect
to protonation. Neutral, mono- and di-protonated ligands are considered. The iron(II) and
ruthenium(II) complexes of these ligands are reported and their properties studied by
variable temperature NMR, UV-visible spectroscopy and single crystal X-ray
crystallography. Subtle changes in substituents were found to have dramatic effects on
crystal packing and some common packing arrangements were identified. A range of
potential ‘expanded ligands’ (complexes which can themselves act as ligands for additional
metal centres), are introduced in the next section. These can be potentially used to bridge
metal centres to form both discrete and infinite structures, in particular in the solid state. In
a systematic study of single crystal X-ray crystal structures of these complexes many were
found to be more flexible than they first appear, and that the crystal packing arrangements
were often sensitive to solvent. The next section describes the first crystallographically
characterized coordination polymers and networks which include metal bis(terpyridine)
units. Self-complementary hydrogen bonding was also found to be a stabilizing motif, with
a number of such structures prepared. The final chapter blends the ideas of previous
sections: 4'-(x-pyridyl) functionalized 2,2',6',2''-terpyridine ligands are used to form
‘expanded ligands’ with iron(II) and ruthenium(II) centres. These were characterized in
solution, with protonation of the distant pendant pyridyl ring found to significantly
influence the MLCT absorption of the complexes. These complexes were incorporated into
two larger structures and characterised by single crystal X-ray crystallography. A selfcomplementary
hydrogen bonded polymer which possesses nanopores through the crystal
lattice is reported. Iron bis(thiocyanate) was also used to form a bridged coordination
polymer
Funding for the Future
This research paper touches on the fundamental issues surrounding inequality in the American educational system, specifically between race and class. Prior research has indicated that minorities and lower class families experience far less ideal and adequate educations than white families with higher incomes. This paper brings together work done by Jonathon Kozol and the Civil Rights Project while using examples from New Hampshire schools in order to emphasize the disparate treatment of children in American schools
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