2 resultados para civic virtue
em CaltechTHESIS
Resumo:
I. Foehn winds of southern California.
An investigation of the hot, dry and dust laden winds
occurring in the late fall and early winter in the Los Angeles
Basin and attributed in the past to the influences of the desert
regions to the north revealed that these currents were of a
foehn nature. Their properties were found to be entirely due
to dynamical heating produced in the descent from the high level
areas in the interior to the lower Los Angeles Basin. Any dust
associated with the phenomenon was found to be acquired from the
Los Angeles area rather than transported from the desert. It was
found that the frequency of occurrence of a mild type foehn of this
nature during this season was sufficient to warrant its classification
as a winter monsoon. This results from the topography of
the Los Angeles region which allows an easy entrance to the air
from the interior by virtue of the low level mountain passes north
of the area. This monsoon provides the mild winter climate of
southern California since temperatures associated with the foehn
currents are far higher than those experienced when maritime air
from the adjacent Pacific Ocean occupies the region.
II. Foehn wind cyclo-genesis.
Intense anticyclones frequently build up over the high level
regions of the Great Basin and Columbia Plateau which lie between
the Sierra Nevada and Cascade Mountains to the west and the Rocky
Mountains to the east. The outflow from these anticyclones produce
extensive foehns east of the Rockies in the comparatively low
level areas of the middle west and the Canadian provinces of
Alberta and Saskatchewan. Normally at this season of the year very
cold polar continental air masses are present over this territory
and with the occurrence of these foehns marked discontinuity surfaces
arise between the warm foehn current, which is obliged to slide over
a colder mass, and the Pc air to the east. Cyclones are
easily produced from this phenomenon and take the form of unstable
waves which propagate along the discontinuity surface between the
two dissimilar masses. A continual series of such cyclones was
found to occur as long as the Great Basin anticyclone is maintained
with undiminished intensity.
III. Weather conditions associated with the Akron disaster.
This situation illustrates the speedy development and
propagation of young disturbances in the eastern United States
during the spring of the year under the influence of the conditionally
unstable tropical maritime air masses which characterise the
region. It also furnishes an excellent example of the superiority
of air mass and frontal methods of weather prediction for aircraft
operation over the older methods based upon pressure distribution.
IV. The Los Angeles storm of December 30, 1933 to January 1, 1934.
This discussion points out some of the fundamental interactions
occurring between air masses of the North Pacific Ocean in connection
with Pacific Coast storms and the value of topographic and
aerological considerations in predicting them. Estimates of rainfall
intensity and duration from analyses of this type may be made and
would prove very valuable in the Los Angeles area in connection with
flood control problems.
Resumo:
The binding and catalytic properties of hen's egg white lysozyme have been studied by a variety of techniques. These studies show that the enzyme has three contiguous binding subsites, A, B, and C. The application of nuclear magnetic resonance (NMR) spectroscopy to probe the binding environment of several saccharides to lysozyme has demonstrated that the reducing end sugar rings of chitotriose, chitobiose and the β-form of N-acetylglucosamine all bind in subsite C. The central sugar ring of chitotriose and the sugar ring at the nonreducing end of chitobiose were found to bind in subsite B, while the nonreducing end sugar residue of chitotriose occupied subsite A. The dynamics of the binding process has also been investigated by NMR. The formation rate constant of chitobiose--and chitotriose-enzyme complexes were found to be about 4 X 10-6 M-1 sec-1 with small activation energies.
The stereochemical path of the lysozyme catalyzed hydrolysis of glycosidic bonds has been shown to proceed with at least 99.7% retention of configuration at C-1 of the sugar. The lysozyme catalyzed hydrolysis of glucosidic bonds has been shown to be largely carbonium ion in character by virtue of the α-deuterium kinetic isotope effect (kH/kD = 1.11) observed for the reaction. It is probable that the mechanism of action of the enzyme involves a carbonium ion intermediate which is stereospecifically quenched by solvent. However, acetamido group participation cannot be ruled out for natural substrates.