9,824 research outputs found
A New Approach to Tagging Data in the Astronomical Literature
Data Tags are strings used in journals to indicate the origin of the
archival data and to enable the reader to recover the data. The NASA/IPAC
Infrared Science Archive (IRSA) has recently introduced a new approach to production
of data tags and recovery of data from them. Many of the data access
services at the IRSA return filtered data sets (such as subsets of source catalogs)
and dynamically created products (such as image cutouts); these dynamically
created products are not saved permanently at the archive. Rather than tag the
data sets from which the query result sets are drawn, the archive tags the query
that generates the results. A single tag can, then, encode a complex dynamic
data set and simplifies the embedding of tags in manuscripts and journals. By
logging user queries and all the parameters for those query as Data Tags, IRSA
can re-create the query and rerun the IRSA service using the same search parameters
used when the Data Tag was created. At the same time, the logs give
a simple count of the actual numbers of queries made to the archive, a powerful
metric of archive usage unobtainable from the Apache web server logs. Currently,
IRSA creates tags for queries to more than 20 data sets, including the
Infrared Astronomical Satellite (IRAS), Cosmic Evolution Survey (COSMOS)
and Spitzer Space Telescope Legacy Data Sets. These tags are returned by the
spatial query engine, Atlas. IRSA plans to create tags for queries to the rest
of its services in late Spring 2007. The archive provides a simple web interface
which recovers a data set that corresponds to the input data tag. Archived data
sets may evolve in time due to improved calibrations or augmentations to the
data set. IRSA’s query based approach guarantees that users always receive the
best available data sets
Spitzer data at the NASA/IPAC Infrared Science Archive (IRSA)
The NASA/IPAC Infrared Science Archive (IRSA) curates and serves science
data sets from NASA’s infrared and submillimeter projects and missions,
including IRAS, 2MASS, MSX, SWAS, ISO, IRTS and from the Spitzer Space
Telescope. All Spitzer data can be accessed from IRSA’s Spitzer mission page
at: http://irsa.ipac.caltech.edu/Missions/spitzer.html
Spitzer Legacy Enhanced Products along with ancillary data are delivered
in six month intervals starting from Fall 2004, until Fall 2006. IRSA continually
ingests the Spitzer data and the ancillary data, and these data are made
accessible through IRSA’s query engines. Legacy products for the C2D, FEPS,
GLIMPSE, GOODS, SINGS and SWIRE projects are accessible through a common
interface http://irsa.ipac.caltech.edu/applications/Atlas. This
engine returns the spatial footprints of observations and provides access to all
flavors of released data sets, including, where appropriate, previews of image
mosaics, 3-color image mosaics and spectra
Atmospheric transition curves for geomagnetically-sensitive cosmic rays Final report
Atmospheric transition curves for geomagnetically sensitive cosmic ray
The Application of the Montage Image Mosaic Engine To The Visualization Of Astronomical Images
The Montage Image Mosaic Engine was designed as a scalable toolkit, written
in C for performance and portability across *nix platforms, that assembles FITS
images into mosaics. The code is freely available and has been widely used in
the astronomy and IT communities for research, product generation and for
developing next-generation cyber-infrastructure. Recently, it has begun to
finding applicability in the field of visualization. This has come about
because the toolkit design allows easy integration into scalable systems that
process data for subsequent visualization in a browser or client. And it
includes a visualization tool suitable for automation and for integration into
Python: mViewer creates, with a single command, complex multi-color images
overlaid with coordinate displays, labels, and observation footprints, and
includes an adaptive image histogram equalization method that preserves the
structure of a stretched image over its dynamic range. The Montage toolkit
contains functionality originally developed to support the creation and
management of mosaics but which also offers value to visualization: a
background rectification algorithm that reveals the faint structure in an
image; and tools for creating cutout and down-sampled versions of large images.
Version 5 of Montage offers support for visualizing data written in HEALPix
sky-tessellation scheme, and functionality for processing and organizing images
to comply with the TOAST sky-tessellation scheme required for consumption by
the World Wide Telescope (WWT). Four online tutorials enable readers to
reproduce and extend all the visualizations presented in this paper.Comment: 16 pages, 9 figures; accepted for publication in the PASP Special
Focus Issue: Techniques and Methods for Astrophysical Data Visualizatio
Sensitivity of a climatologically-driven sea ice model to the ocean heat flux
Ocean heat flux sensitivity was studied on a numerical model of sea ice covering the Weddell Sea region of the southern ocean. The model is driven by mean monthly climatological atmospheric variables. For each model run, the ocean heat flux is uniform in both space and time. Ocean heat fluxes below 20 W m to the minus 2 power do not provide sufficient energy to allow the ice to melt to its summertime thicknesses and concentrations by the end of the 14 month simulation, whereas ocean heat fluxes of 30 W m to the minus 2 power and above result in too much ice melt, producing the almost total disappearance of ice in the Weddell Sea by the end of the 14 months. These results are dependent on the atmospheric forcing fields
Aperture synthesis for microwave radiometers in space
A technique is described for obtaining passive microwave measurements from space with high spatial resolution for remote sensing applications. The technique involves measuring the product of the signal from pairs of antennas at many different antenna spacings, thereby mapping the correlation function of antenna voltage. The intensity of radiation at the source can be obtained from the Fourier transform of this correlation function. Theory is presented to show how the technique can be applied to large extended sources such as the Earth when observed from space. Details are presented for a system with uniformly spaced measurements
High mass star formation in the galaxy
The Galactic distributions of HI, H2, and HII regions are reviewed in order to elucidate the high mass star formation occurring in galactic spiral arms and in active galactic nuclei. Comparison of the large scale distributions of H2 gas and radio HII regions reveals that the rate of formation of OB stars depends on (n sub H2) sup 1.9 where (n sub H2) is the local mean density of H2 averaged over 300 pc scale lengths. In addition the efficiency of high mass star formation is a decreasing function of cloud mass in the range 200,000 to 3,000,000 solar mass. These results suggest that high mass star formation in the galactic disk is initiated by cloud-cloud collisions which are more frequent in the spiral arms due to orbit crowding. Cloud-cloud collisions may also be responsible for high rates of OB star formation in interacting galaxies and galactic nuclei. Based on analysis of the Infrared Astronomy Satellite (IRAS) and CO data for selected GMCs in the Galaxy, the ratio L sub IR/M sub H2 can be as high as 30 solar luminosity/solar mass for GMCs associated with HII regions. The L sub IR/M sub H2 ratios and dust temperature obtained in many of the high luminosity IRAS galaxies are similar to those encountered in galactic GMCs with OB star formation. High mass star formation is therefore a viable explanation for the high infrared luminosity of these galaxies
The Montage Image Mosaic Service: Custom Image Mosaics On-Demand
The Montage software suite has proven extremely useful as a general engine for reprojecting, background matching, and mosaicking astronomical image data from a wide variety of sources. The processing algorithms support all common World Coordinate System (WCS) projections and have been shown to be both astrometrically accurate and flux conserving. The background ‘matching’ algorithm does not remove background flux but rather finds the best compromise background based on all the input and matches the individual images to that. The Infrared Science Archive (IRSA), part of the Infrared Processing and Analysis Center (IPAC) at Caltech, has now wrapped the Montage software as a CGI service and provided a compute and request management infrastructure capable of producing approximately 2 TBytes / day of image mosaic output (e.g. from 2MASS and SDSS data). Besides the basic Montage engine, this service makes use of a 16-node LINUX cluster (dual processor, dual core) and the ROME request management software developed by the National Virtual Observatory (NVO). ROME uses EJB/database technology to manage user requests, queue processing and load balance between users, and managing job monitoring and user notification. The Montage service will be extended to process userdefined data collections, including private data uploads
Simulating Ability: Representing Skills in Games
Throughout the history of games, representing the abilities of the various
agents acting on behalf of the players has been a central concern. With
increasingly sophisticated games emerging, these simulations have become more
realistic, but the underlying mechanisms are still, to a large extent, of an ad
hoc nature. This paper proposes using a logistic model from psychometrics as a
unified mechanism for task resolution in simulation-oriented games
The Interaction of Obesity Related Genotypes, Phenotypes, and Economics: An Experimental Economics Approach with Mice
Food intake is greatly influenced by economic factors. Consequently, neuroeconomics has been identified as a new and important area for understanding the interaction between genotypes and phenotypes related to food intake. A foundational element of economics is choice between alternatives. Changing food choices are a central element in the explanation of the increasing obesity rates in human populations. The purpose of this research is to incorporate the key element of choice into the investigation of food intake and weight-related phenotypes for mice in an operant chamber setting. Using normal mice, and mice with a mutation in the Tubby gene (Tub-Mut) which results in adult onset obesity, this research will investigate different behavioral responses among genotypes, as well as unexplored phenotype outcomes when mice are confronted with a falling price of a high fat food relative to a low fat food. Results for both genotypes indicate that as the price of the high fat food falls, consumption of that food increases, but consumption of the low fat food does not decrease in a compensatory fashion. For both genotypes, weight and body fat percentage increases with decreasing high fat food price, but ghrelin and leptin levels do not significantly change. The Tub-Mut shows a significant increase in the area under the glucose tolerance curve, suggestive of a diabetic state. These results show that accounting for choice in neuroeconomic studies is important to understanding the complex regulation of body weight and diabetes.Food Consumption/Nutrition/Food Safety,
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