3,341 research outputs found
Simplified landscapes for optimization of shaken lattice interferometry
Motivated by recent results using shaken optical lattices to perform atom
interferometry, we explore splitting of an atom cloud trapped in a
phase-modulated ("shaken") optical lattice. Using a simple analytic model we
are able to show that we can obtain the simplest case of splitting via single-frequency shaking. This is confirmed both
via simulation and experiment. Furthermore, we are able to split with a
relative phase between the two split arms of or depending on
our shaking frequency. Addressing higher-order splitting, we determine that
splitting is sufficient to be able to accelerate the
atoms in counter-propagating lattices. Finally, we show that we can use a
genetic algorithm to optimize and splitting to within by restricting our
optimization to the resonance frequencies corresponding to single- and
two-photon transitions between Bloch bands
A collection of lower thermospheric /100 to 300 km altitude/ chemical composition, temperature, and mass density data
Tabulated lower thermospheric chemical composition, temperature, and mass density dat
A reference atmosphere for patrick afb, florida, annual /1963 revision/
Reference atmosphere for cape kennedy based on statistical parameters of pressure-height, temperature, and relative humidity at constant pressure level
Effective Immersive Analytics for Everyday Use
Data visualization is an important field of work that takes in uncountable amounts of indexes to create an easy-to-read interpretation of what was previously unreadable. Immersive analytics is the new field that brings 3D data visualization to virtual reality, immersing users directly into the data. Focusing on bringing humans and computers closer together through natural function can benefit the world of data science. In order to accurately utilize this field to benefit this world, principles must be laid out and observed to see which techniques and methods are best fit for an everyday immersive analytics platform. Our findings show that, within an immersive 3D environment, users that perform in a static state where no physical or virtual navigation of the environment is present is more beneficial to the interpretation of the data. While reported gender identity does not seem to affect the time to complete the given task, it seems the age of a given participant is one factor which affects the task time
The [alpha/Fe] Ratios in Dwarf Galaxies: Evidence for a Non-universal Stellar Initial Mass Function?
It is well established that the [alpha/Fe] ratios in elliptical galaxies
increase with galaxy mass. This relation holds also for early-type dwarf
galaxies, although it seems to steepen at low masses. The [alpha/Fe] vs. mass
relation can be explained assuming that smaller galaxies form over longer
timescales (downsizing), allowing a larger amount of Fe (mostly produced by
long-living Type Ia Supernovae) to be released and incorporated into newly
forming stars. Another way to obtain the same result is by using a flatter
initial mass function (IMF) in large galaxies, increasing in this way the
number of Type II Supernovae and therefore the production rate of
alpha-elements. The integrated galactic initial mass function (IGIMF) theory
predicts that the higher the star formation rate, the flatter the IMF. We have
checked, by means of semi-analytical calculations, that the IGIMF theory,
combined with the downsizing effect (i.e. the shorter duration of the star
formation in larger galaxies), well reproduces the observed [alpha/Fe] vs. mass
relation. In particular, we show a steepening of this relation in dwarf
galaxies, in accordance with the available observations.Comment: 4 pages, 2 figures; to appear in the proceedings of the JENAM 2010
Symposium on Dwarf Galaxies (Lisbon, September 9-10, 2010
Flow establishment in a generic scramjet combustor
The establishment of a quasi-steady flow in a generic scramjet combustor was studied for the case of a time varying inflow to the combustor. Such transient flow is characteristic of the reflected shock tunnel and expansion tube test facilities. Several numerical simulations of hypervelocity flow through a straight duct combustor with either a side wall step fuel injector or a centrally located strut injector are presented. Comparisons were made between impulsively started but otherwise constant flow conditions (typical of the expansion tube or tailored operations of the reflected shock tunnel) and the relaxing flow produced by the 'undertailored' operations of the reflected shock tunnel. Generally the inviscid flow features, such as the shock pattern and pressure distribution, were unaffected by the time varying inlet conditions and approached steady state in approx. the times indicated by experimental correlations. However, viscous features, such as heat transfer and skin friction, were altered by the relaxing inlet flow conditions
Correction to "Integrative analysis of transcriptomics, proteomics and metabolomics data of white adipose and liver tissue of high-fat diet and rosiglitazone-treated insulin-resistant mice identified pathway alterations and molecular hubs"
The Variation of Integrated Star IMFs among Galaxies
The integrated galaxial initial mass function (IGIMF) is the relevant
distribution function containing the information on the distribution of stellar
remnants, the number of supernovae and the chemical enrichment history of a
galaxy. Since most stars form in embedded star clusters with different masses
the IGIMF becomes an integral of the assumed (universal or invariant) stellar
IMF over the embedded star-cluster mass function (ECMF). For a range of
reasonable assumptions about the IMF and the ECMF we find the IGIMF to be
steeper (containing fewer massive stars per star) than the stellar IMF, but
below a few Msol it is invariant and identical to the stellar IMF for all
galaxies. However, the steepening sensitively depends on the form of the ECMF
in the low-mass regime. Furthermore, observations indicate a relation between
the star formation rate of a galaxy and the most massive young stellar cluster
in it. The assumption that this cluster mass marks the upper end of a
young-cluster mass function leads to a connection of the star formation rate
and the slope of the IGIMF above a few Msol. The IGIMF varies with the star
formation history of a galaxy. Notably, large variations of the IGIMF are
evident for dE, dIrr and LSB galaxies with a small to modest stellar mass. We
find that for any galaxy the number of supernovae per star (NSNS) is suppressed
relative to that expected for a Salpeter IMF. Dwarf galaxies have a smaller
NSNS compared to massive galaxies. For dwarf galaxies the NSNS varies
substantially depending on the galaxy assembly history and the assumptions made
about the low-mass end of the ECMF. The findings presented here may be of some
consequence for the cosmological evolution of the number of supernovae per
low-mass star and the chemical enrichment of galaxies of different mass.Comment: 27 pages, accepted for publication by Ap
An estimate of the solar cyclic variation of the Martian upper atmosphere
Mathematical model for estimating probable cyclic variations in Martian atmosphere during solar activit
- …