41,325 research outputs found
The Cowl - v.3 - n.9 - Nov 24, 1937
The Cowl - student newspaper of Providence College. Volume 3, Number 9 - Nov 24, 1937. 4 pages
216 Jewish Hospital of St. Louis
https://digitalcommons.wustl.edu/bjc_216/1058/thumbnail.jp
216 Jewish Hospital of St. Louis
https://digitalcommons.wustl.edu/bjc_216/1055/thumbnail.jp
Bounds on the Speed and on Regeneration Times for Certain Processes on Regular Trees
We develop a technique that provides a lower bound on the speed of transient
random walk in a random environment on regular trees. A refinement of this
technique yields upper bounds on the first regeneration level and regeneration
time. In particular, a lower and upper bound on the covariance in the annealed
invariance principle follows. We emphasize the fact that our methods are
general and also apply in the case of once-reinforced random walk. Durrett,
Kesten and Limic (2002) prove an upper bound of the form for the
speed on the -ary tree, where is the reinforcement parameter. For
we provide a lower bound of the form , where
is the survival probability of an associated branching process.Comment: 21 page
SHG microscopic observations of polar state in Li-doped KTaO3 under electric field
Incipient ferroelectric KTaO3 with off-center Li impurity of the critical
concentration of 2.8 mol% was investigated in order to clarify the dipole glass
state under electric field. Using optical second-harmonic generation (SHG)
microscope, we observed a marked history dependence of SHG intensity through
zero-field cooling (ZFC), zero-field heating (ZFH), field heating after ZFC
(FH/ZFC) and FH after field cooling (FH/FC). These show different paths with
respect to temperature: In the ZFC/ZFH process, weak SHG was observed at low
temperature, while in the FH/ZFC process, relatively high SHG appears in a
limited temperature range below TF depending on the field strength, and in the
FC and FH/FC processes, the SHG exhibits ferroelectric-like temperature
dependence: it appears at the freezing temperature of 50K, increases with
decreasing temperature and has a tendency of saturation. These experimental
results strongly suggest that dipole glass state or polar nano-clusters which
gradually freezes with decreasing temperature is transformed into
semi-macroscopic polar state under the electric field. However at sufficiently
low temperature, the freezing is so strong that the electric field cannot
enlarge the polar clusters. These experimental results show that the polar
nano-cluster model similar to relaxors would be more relevant in KTaO3 doped
with the critical concentration of Li. Further experiments on the anisotropy of
SHG determine that the average symmetry of the field-induced polar phase is
tetragonal 4mm or 4, which is also confirmed by the X-ray diffraction
measurement.Comment: 26 pages, 8 figures, 1 tabl
The development of cases for teaching administration of the nursing services by the case method.
Thesis (M.S.)--Boston Universit
The development of cases for teaching administration of the nursing services by the case method.
Thesis (M.S.)--Boston Universit
The afterglow and kilonova of the short GRB 160821B
GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized
by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at
z=0.1613, at a projected physical offset of 16 kpc from the galaxy's center. We
present X-ray, optical/nIR and radio observations of its counterpart and model
them with two distinct components of emission: a standard afterglow, arising
from the interaction of the relativistic jet with the surrounding medium, and a
kilonova, powered by the radioactive decay of the sub-relativistic ejecta.
Broadband modeling of the afterglow data reveals a weak reverse shock
propagating backward into the jet, and a likely jet-break at 3.5 d. This is
consistent with a structured jet seen slightly off-axis while expanding into a
low-density medium. Analysis of the kilonova properties suggests a rapid
evolution toward red colors, similar to AT2017gfo, and a low nIR luminosity,
possibly due to the presence of a long-lived neutron star. The global
properties of the environment, the inferred low mass (M_ej < 0.006 Msun) and
velocities (v > 0.05 c) of lanthanide-rich ejecta are consistent with a binary
neutron star merger progenitor.Comment: 14 pages, 6 figures, MNRAS, in press. Moderate revision, added Figure
5 and X-ray data to Table
- …