1,477 research outputs found
Common-Resolution Convolution Kernels for Space- and Ground-Based Telescopes
Multi-wavelength study of extended astronomical objects requires combining
images from instruments with differing point spread functions (PSFs). We
describe the construction of convolution kernels that allow one to generate
(multi-wavelength) images with a common PSF, thus preserving the colors of the
astronomical sources. We generate convolution kernels for the cameras of the
Spitzer Space Telescope, Herschel Space Observatory, Galaxy Evolution Explorer
(GALEX), Wide-field Infrared Survey Explorer (WISE), ground-based optical
telescopes (Moffat functions and sum of Gaussians), and Gaussian PSFs. These
kernels allow the study of the Spectral Energy Distribution (SED) of extended
objects, preserving the characteristic SED in each pixel. The convolution
kernels and the IDL packages used to construct and use them are made publicly
available
The World Distribution of Household Wealth
There has been much recent research on the world distribution of income, but also growing recognition of the importance of other contributions to well-being, including those of household wealth. Wealth is important in providing security and opportunity, particularly in poorer countries that lack full social safety nets and adequate facilities for borrowing and lending. We find, however, that it is precisely in the latter countries where household wealth is the lowest, both in absolute and relative terms. Globally, wealth is more concentrated than income both on an individual and national basis. Roughly 30 per cent of world wealth is found in each of North America, Europe, and the rich Asian-Pacific countries. These areas account for virtually all of the world?s top 1 per cent of wealth holders. On an official exchange rate basis India accounts for about a quarter of the adults in the bottom three global wealth deciles while China provides about a third of those in the fourth to eighth deciles. If current growth trends continue, India, China and the transition countries will move up in the global distribution, and the lower deciles will be increasingly dominated by countries in Africa, Latin American and poor parts of the Asian-Pacific region. Thus wealth may continue to be lowest in areas where it is needed the most.wealth, net worth, personal assets, wealth inequality, households, balance sheets, portfolios
IceCube's In-Ice Radio Extension: Status and Results
In 2006-2010, several Radio Frequency (RF) detectors and calibration
equipment were deployed as part of the IceCube array at depths between 5 to
1400 meters in preparation for a future large scale GZK neutrino detector.
IceCube's deep holes and well-established data handling system provide a unique
opportunity for deep-ice RF detection studies at the South-Pole. We will
present verification and calibration results as well as a status-review of
ongoing analyses such as ice-properties, RF noise and reconstruction
algorithms.Comment: 4 pages, 6 figures, to appear in the proceedings of the Acoustic and
Radio EeV Neutrino detection Activities (ARENA) 2010 conferenc
Toward Pay Equity: A Case Study of Washington DCs Wage Boost for Early Childhood Educators
This short report presents findings from interviewsâwith key informants, including DC early childhood education leaders, advocates, and implementation partners; parents and legal guardians of young children enrolled in licensed DC child care facilities; and child care center directors and home and expanded home providersâon the nation's first early childhood educator wage supplement with dedicated public funding
Metamaterials for light rays: ray optics without wave-optical analog in the ray-optics limit
Volumes of sub-wavelength electromagnetic elements can act like homogeneous
materials: metamaterials. In analogy, sheets of optical elements such as prisms
can act ray-optically like homogeneous sheet materials. In this sense, such
sheets can be considered to be metamaterials for light rays (METATOYs).
METATOYs realize new and unusual transformations of the directions of
transmitted light rays. We study here, in the ray-optics and scalar-wave
limits, the wave-optical analog of such transformations, and we show that such
an analog does not always exist. Perhaps, this is the reason why many of the
ray-optical possibilities offered by METATOYs have never before been
considered.Comment: 10 pages, 3 figures, references update
Heating and cooling of the neutral ISM in the NGC4736 circumnuclear ring
The manner in which gas accretes and orbits within circumnuclear rings has
direct implications for the star formation process. In particular, gas may be
compressed and shocked at the inflow points, resulting in bursts of star
formation at these locations. Afterwards the gas and young stars move together
through the ring. In addition, star formation may occur throughout the ring, if
and when the gas reaches sufficient density to collapse under gravity. These
two scenarios for star formation in rings are often referred to as the `pearls
on a string' and `popcorn' paradigms. In this paper, we use new Herschel PACS
observations, obtained as part of the KINGFISH Open Time Key Program, along
with archival Spitzer and ground-based observations from the SINGS Legacy
project, to investigate the heating and cooling of the interstellar medium in
the nearby star-forming ring galaxy, NGC4736. By comparing spatially resolved
estimates of the stellar FUV flux available for heating, with the gas and dust
cooling derived from the FIR continuum and line emission, we show that while
star formation is indeed dominant at the inflow points in NGC 4736, additional
star formation is needed to balance the gas heating and cooling throughout the
ring. This additional component most likely arises from the general increase in
gas density in the ring over its lifetime. Our data provide strong evidence,
therefore, for a combination of the two paradigms for star formation in the
ring in NGC4736.Comment: accepted for publication in A&
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