8,250 research outputs found
THE BALANCE BETWEEN FIGHTING STREET GANGS AND ADHERING TO THE CONSTITUTION IN SOUTHERN CALIFORNIA
Longitudinal response functions of 3H and 3He
Trinucleon longitudinal response functions R_L(q,omega) are calculated for q
values up to 500 MeV/c. These are the first calculations beyond the threshold
region in which both three-nucleon (3N) and Coulomb forces are fully included.
We employ two realistic NN potentials (configuration space BonnA, AV18) and two
3N potentials (UrbanaIX, Tucson-Melbourne). Complete final state interactions
are taken into account via the Lorentz integral transform technique. We study
relativistic corrections arising from first order corrections to the nuclear
charge operator. In addition the reference frame dependence due to our
non-relativistic framework is investigated. For q less equal 350 MeV/c we find
a 3N force effect between 5 and 15 %, while the dependence on other theoretical
ingredients is small. At q greater equal 400 MeV/c relativistic corrections to
the charge operator and effects of frame dependence, especially for large
omega, become more important. In comparison with experimental data there is
generally a rather good agreement. Exceptions are the responses at excitation
energies close to threshold, where there exists a large discrepancy with
experiment at higher q. Concerning the effect of 3N forces there are a few
cases, in particular for the R_L of 3He, where one finds a much improved
agreement with experiment if 3N forces are included.Comment: 26 pages, 9 figure
The HERMES Solar Atlas and the spectroscopic analysis of the seismic solar analogue KIC3241581
Solar-analog stars provide an excellent opportunity to study the Sun's
evolution, i.e. the changes with time in stellar structure, activity, or
rotation for solar-like stars. The unparalleled photometric data from the NASA
space telescope Kepler allows us to study and characterise solar-like stars
through asteroseismology. We aim to spectroscopically investigate the
fundamental parameter and chromospheric activity of solar analogues and twins,
based on observations obtained with the HERMES spectrograph and combine them
with asteroseismology. Therefore, we need to build a solar atlas for the
spectrograph, to provide accurate calibrations of the spectroscopically
determined abundances of solar and late type stars observed with this
instrument and thus perform differential spectral comparisons. We acquire
high-resolution and high signal-to-noise spectroscopy to construct three solar
reference spectra by observing the reflected light of Vesta and Victoria
asteroids and Europa (100<S/N<450) with the \Hermes spectrograph. We then
observe the Kepler solar analog KIC3241581 (S/N~170). We constructed three
solar spectrum atlases from 385 to 900 nm obtained with the Hermes spectrograph
from observations of two bright asteroids and Europa. A comparison between our
solar spectra atlas to the Kurucz and HARPS solar spectrum shows an excellent
agreement. KIC3241581 was found to be a long-periodic binary system. The
fundamental parameter for the stellar primary component are Teff=5689+/-11K,
logg=4.385+/-0.005, [Fe/H]=+0.22+/-0.01, being in agreement with the published
global seismic values confirming its status of solar analogue. KIC 3241581 is a
metal rich solar analogue with a solar-like activity level in a binary system
of unknown period. The chromospheric activity level is compatible to the solar
magnetic activity.Comment: 12 pages, 8 figures, accepted for publication in A&
Primary display latency criteria based on flying qualities and performance data
With a pilots' increasing use of visual cue augmentation, much requiring extensive pre-processing, there is a need to establish criteria for new avionics/display design. The timeliness and synchronization of the augmented cues is vital to ensure the performance quality required for precision mission task elements (MTEs) where augmented cues are the primary source of information to the pilot. Processing delays incurred while transforming sensor-supplied flight information into visual cues are unavoidable. Relationships between maximum control system delays and associated flying qualities levels are documented in MIL-F-83300 and MIL-F-8785. While cues representing aircraft status may be just as vital to the pilot as prompt control response for operations in instrument meteorological conditions, presently, there are no specification requirements on avionics system latency. To produce data relating avionics system latency to degradations in flying qualities, the Navy conducted two simulation investigations. During the investigations, flying qualities and performance data were recorded as simulated avionics system latency was varied. Correlated results of the investigation indicates that there is a detrimental impact of latency on flying qualities. Analysis of these results and consideration of key factors influencing their application indicate that: (1) Task performance degrades and pilot workload increases as latency is increased. Inconsistency in task performance increases as latency increases. (2) Latency reduces the probability of achieving Level 1 handling qualities with avionics system latency as low as 70 ms. (3) The data suggest that the achievement of desired performance will be ensured only at display latency values below 120 ms. (4) These data also suggest that avoidance of inadequate performance will be ensured only at display latency values below 150 ms
Photospheric and chromospheric magnetic activity of seismic solar analogs. Observational inputs on the solar/stellar connection from Kepler and Hermes
We identify a set of 18 solar analogs among the seismic sample of solar-like
stars observed by the Kepler satellite rotating between 10 and 40 days. This
set is constructed using the asteroseismic stellar properties derived using
either the global oscillation properties or the individual acoustic
frequencies. We measure the magnetic activity properties of these stars using
observations collected by the photometric Kepler satellite and by the
ground-based, high-resolution Hermes spectrograph mounted on the Mercator
telescope. The photospheric (Sph) and chromospheric (S index) magnetic activity
levels of these seismic solar analogs are estimated and compared in relation to
the solar activity. We show that the activity of the Sun is comparable to the
activity of the seismic solar analogs, within the maximum-to-minimum temporal
variations of the 11-year solar activity cycle 23. In agreement with previous
studies, the youngest stars and fastest rotators in our sample are actually the
most active. The activity of stars older than the Sun seems to not evolve much
with age. Furthermore, the comparison of the photospheric, Sph, with the
well-established chromospheric, S index, indicates that the Sph index can be
used to provide a suitable magnetic activity proxy which can be easily
estimated for a large number of stars from space photometric observations.Comment: Accepted for publication in A&
Paleomagnetic Evidence of Vertical Axis Block Rotations from the Mesozoic of Northern Chile
We present paleomagnetic results for three Mesozoic formations from northern Chile: La Ternera Formation (Upper Triassic), Quebrada Monardes Formation (Upper Jurassic); Cerrillos Formation (Upper Cretaceous). Results from the Cerrillos are divided into eastern (Cuesta El Gao (CEG)) and western (Elisa De Bordo (EBD)) localities. Most specimens from La Ternera volcanic and sedimentary rocks are magnetically stable, as shown by alternating field and thermal demagnetization. More complicated but still reliable results were obtained from Quebrada Monardes red beds. Normal and reverse polarities are present in both units; means of both populations are antiparallel at 95% confidence. The Quebrada Monardes Formation also yields positive conglomerate and fold tests. Paleomagnetic poles for La Ternera and Quebrada- Monardes are 60.9S, 218.3E (A95, 7.8°), and 66.9S, 191.6E (A95, 12.7°), respectively. Comparison with appropriate reference poles shows that this region of Chile has undergone about 25° of clockwise rotation, with negligible latitudinal transport. Cerrillos CEG results are less reliable and possibly complicated by remag- netization during emplacement of early Tertiary intrusives. Most Cerrillos EDB specimens are stable, but marked increase in scatter upon unfolding suggests remagnetization. Results for the Cerrillos CEG locality, which is contiguous to the sampling area of the La Ternera and Quebrada Monardes formations, show only about half the rotation of those two units, suggesting that rotation commenced after deposition of the Quebrada Monardes rocks in the Late Jurassic and was approximately half complete by the time Cerrillos CEG rocks acquired their magnetization. Cerrillos EDB results come from an area approximately 40 km to the west; these show roughly 45° of clockwise rotation. Dispersion is very low between EDB sites, suggesting that secular variation may not be completely averaged. Nevertheless, the great difference in direct:ion between the two Cerrillos localities suggests that they lie in different structural blocks
Coupled-channels effects in elastic scattering and near-barrier fusion induced by weakly bound nuclei and exotic halo nuclei
The influence on fusion of coupling to the breakup process is investigated
for reactions where at least one of the colliding nuclei has a sufficiently low
binding energy for breakup to become an important process. Elastic scattering,
excitation functions for sub-and near-barrier fusion cross sections, and
breakup yields are analyzed for Li+Co. Continuum-Discretized
Coupled-Channels (CDCC) calculations describe well the data at and above the
barrier. Elastic scattering with Li (as compared to Li) indicates
the significant role of breakup for weakly bound projectiles. A study of
He induced fusion reactions with a three-body CDCC method for the
He halo nucleus is presented. The relative importance of breakup and
bound-state structure effects on total fusion is discussed.Comment: 29 pages, 9 figure
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