1,110 research outputs found
Constraints on the active tectonics of the Friuli/NW Slovenia area from CGPS measurements and three-dimensional kinematic modeling
We use site velocities from continuous GPS (CGPS) observations and kinematic
modeling to investigate the active tectonics of the Friuli/NW Slovenia area. Data from 42
CGPS stations around the Adriatic indicate an oblique collision, with southern Friuli
moving NNW toward northern Friuli at the relative speed of 1.6 to 2.2 mm/a. We
investigate the active tectonics using 3DMove, a three-dimensional kinematic model tool.
The model consists of one indenter-shaped fault plane that approximates the Adriatic
plate boundary. Using the ‘‘fault-parallel flow’’ deformation algorithm, we move the
hanging wall along the fault plane in the direction indicated by the GPS velocities. The
resulting strain field is used for structural interpretation. We identify a pattern of
coincident strain maxima and high vorticity that correlates well with groups of
hypocenters of major earthquakes (including their aftershocks) and indicates the
orientation of secondary, active faults. The pattern reveals structures both parallel and
perpendicular to the strike of the primary fault. In the eastern sector, which shows more
complex tectonics, these two sets of faults probably form an interacting strike-slip
system
A Uniform Analysis of the Ly-alpha forest at z = 0 - 5: I. The sample and distribution of clouds at z > 1.7
We present moderate resolution data for 39 QSOs at z 2 obtained at
the Multiple Mirror Telescope. These data are combined with spectra of
comparable resolution of 60 QSOs with redshifts greater than 1.7 found in the
literature to investigate the distribution of Ly-alpha forest lines in redshift
and equivalent width. We find a value for , the parameter describing
the number distribution of Ly-alpha forest lines in redshift, of
for lines stronger than a rest equivalent width of 0.32 , in good
agreement with some previous studies. The Kolmogorov-Smirnov test was applied
to the data and it is found that this single power law is a good fit over the
relevant redshift ranges. Simulations of the Lyman alpha forest were performed
to determine the completeness of the line lists and to test how well the
analysis the underlying line statistics, given this level of completeness.Comment: minor corrections to text, 37 Latex pages, 11 encapsulated Postscript
figures, uses emulateapj.sty, To appear in the Sept. 2000 ApJS, line lists
and spectra available at http://qso.as.arizona.edu/~jscott/Spectra/index.htm
Implications of flexible spacer rotational processes on the liquid crystal behavior of 4,5-dihydroisoxazole benzoate dimers
The synthesis of some novel non-symmetric liquid crystal dimers, {3-[4-(octyloxyphenyl)]-4,5-dihydroisoxazol-5-yl}alkyl 4-(decyloxy)benzoates (5a–d) and 4-{3-[4-(octyloxyphenyl)]-4,5-dihydroisoxazol-5-yl}alkyl 4-{[6-(octyloxy)naphthalen-2-yl]ethynyl}benzoate (9a–d), are reported. The liquid-crystalline properties, theoretical calculations based on the conformational aspects of the flexible alkyl spacer and X-ray experiments are discussed. The syntheses of the key intermediates, 2-{3-[4-(octyloxy)phenyl]-4,5-dihydroisoxazol-5-yl}alkanol (3a–d), presenting the flexible alkyl spacer were achieved through [3+2] cycloaddition reactions between nitrile oxides, which were generated in situ by oxidation of the respective aromatic oximes, and dipolarophile alkenols (CH2[double bond, length as m-dash]CH(CH2)nOH, n = 1, 2, 3, and 4). The benzoates 5a–d were synthesized through esterification of 3a–d and p-n-decyloxybenzoic acid (4). The esters 9a–d were synthesized through derivatization of isoxazolines 3a–d into 4-{3-[4-(octyloxyphenyl)]-4,5-dihydroisoxazol-5-yl}alkyl 4-bromobenzoate (7a–d) followed by a Sonogashira reaction with 2-ethynyl-6-octyloxynaphthalene (8). 5a and 5b showed a monotropic smectic C phase. 9a/c displayed a enantiotropic nematic (N) mesophase, whereas 9b/d showed a monotropic nematic mesophase. No mesophase was observed for 7a–d. An odd–even effect was observed for 5a–d and 9a–d associated with the crystal to isotropic phase transition and crystal to nematic phase, respectively, as the length of the spacer was increased from 1 to 4 carbon atoms. The transitional properties were higher for odd-numbered members (n = 1 and 3) for all of the series studied. The X-ray data of compounds 5a and 5b are in agreement with polarizing optical microscopy observations with the assignment of an SmC mesophase. Density functional theory calculations using the B3LYP hybrid functional with the level 6-311G(d,p) basis set were performed for molecules 5a–d to correlate the conformation of the flexible spacer and the transitional properties. The conformational analysis showed that the most stable conformation for 5a–d is one where all of the carbon atoms of the flexible spacer are orientated at 180° (antiperiplanar orientation) except for 5a because the spacer is too short. The odd-numbered members have a more bent shape and are less elongated molecules than the even-numbered members. Thus, mesomorphic behavior is dictated by the conformational constraint imposed by the flexible spacer on the mesogenic groups
PCM telemetry data compression study, phase 1 Final report, 15 Sep. 1964 - 15 Aug. 1965
Pulse Code Modulation /PCM/ telemetry data compression study using S-6 Explorer XVII DAT
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Sensitivity of the Brewer-Dobson circulation and polar vortex variability to parameterized nonorographic gravity wave drag in a high-resolution atmospheric model
The role of parametrized nonorographic gravity wave drag (NOGWD) and its seasonal interaction with the resolved wave drag in the stratosphere has been extensively studied in low-resolution (coarser than 1.9 x 2.5 degrees) climate models but is comparatively unexplored in higher-resolution models. Using the European Centre for Medium-Range Weather Forecasts Integrated Forecast System at 0.7 x 0.7 degrees resolution, the wave drivers of the Brewer-Dobson circulation are diagnosed and the circulation sensitivity to the NOGW launch flux is explored. NOGWs are found to account for nearly 20% of the lower stratospheric Southern Hemisphere (SH) polar cap downwelling and for less than 10% of the lower-stratospheric tropical upwelling and Northern Hemisphere (NH) polar cap downwelling. Despite these relatively small numbers, there are complex interactions between NOGWD and resolved wave drag, in both polar regions. Seasonal cycle analysis reveals a temporal offset in the resolved and parametrized wave interaction: The NOGWD response to altered source fluxes is largest in mid-winter, while the resolved wave response is largest in the late winter and spring. This temporal offset is especially prominent in the SH. The impact of NOGWD on sudden stratospheric warming (SSW) life-cycles and the final warming date in the SH is also investigated. An increase in NOGWD leads to an increase in SSW frequency, reduction in amplitude and persistence, and an earlier recovery of the stratopause following a SSW event. The SH final warming date is also brought forward when NOGWD is increased. Thus, NOGWD is still found to be a very important parameterization for stratospheric dynamics even in a high-resolution atmospheric model
Lyman Alpha Forest towards B2 1225+317
We present observations of the Lyman alpha forest towards B2 1225+317 taken
at a resolution of 18 km/s. A clean sample of Lyman alpha forest lines is
extracted after a careful profile fitting analysis and removal of absorption
lines of heavy elements. The sample is analyzed for statistical properties.
Eighty percent of the column densities are < 10^{14} cm^{-2}. A single power
law is inconsistent with the column density distribution and a steepening/break
in the distribution is indicated. The average velocity dispersion parameter is
29.4 km/s. We find 3 sigma evidence for a correlation between column density
and the velocity dispersion parameter. The correlation, however, is mainly due
to narrow lines and weakens to 1.2 sigma if lines with velocity dispersion
parameter smaller than 20 km/s are excluded. An excess of line pairs with
velocity separation 100 km/s over the expected number is found.Comment: latex(mn.sty), 6 figures (available on request from
[email protected] or [email protected]), to appear in MNRA
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105-K east sandfilter backwash line sample analysis report: Third campaign
This project seeks to produce uranium (U) and plutonium (Pu) analyses of samples taken from the KE basin filter backwash line each time the sand filter is backwashed. K Basin operations will use the analytical results to determine additions of fissile materials to the backwash sludge pit and thereby maintain a running inventory of fissile elements in the pit. K Basin operations must not exceed a certain total inventory in order to be within a criticality specification. The third campaign of this project consisted of three samples, numbered by the customer 245KEB, 246KEB, and 247KEB. A revised letter of instruction controlled their processing
The structural properties and star formation history of Leo T from deep LBT photometry
We present deep, wide-field g and r photometry of the transition type dwarf
galaxy Leo T, obtained with the blue arm of the Large Binocular Telescope. The
data confirm the presence of both very young (5
Gyr) stars. We study the structural properties of the old and young stellar
populations by preferentially selecting either population based on their color
and magnitude. The young population is significantly more concentrated than the
old population, with half-light radii of 104+-8 and 148+-16 pc respectively,
and their centers are slightly offset. Approximately 10% of the total stellar
mass is estimated to be represented by the young stellar population. Comparison
of the color-magnitude diagram (CMD) with theoretical isochrones as well as
numerical CMD-fitting suggest that star formation began over 10 Gyr ago and
continued in recent times until at least a few hundred Myr ago. The CMD-fitting
results are indicative of two distinct star formation bursts, with a quiescent
period around 3 Gyr ago, albeit at low significance. The results are consistent
with no metallicity evolution and [Fe/H] ~ -1.5 over the entire age of the
system. Finally, the data show little if any sign of tidal distortion of Leo T.Comment: 8 pages, 9 figures, some small textual changes, accepted for
publication in the Astrophysical Journa
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