CATLAC - Calibration and Validation Analysis Tool of Local Area Coverage for the SeaWiFS Mission

Calibration and validation Analysis Tool of Local Area Coverage (CATLAC) is an analysis package for selecting and graphically displaying Earth and space targets for calibration and validation activities on a polar orbiting satellite. The package is written in the Interactive Data Language (IDL) and includes a graphical user interface. Although it is designed specifically for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission, the package can be used for analysis on other Earth-viewing missions. An individual can use text or graphical methods in CATLAC to select Earth targets to be scanned by a satellite. Additional onboard calibration activities (such as observations of the moon, or solar irradiance from a solar diffuser), which use data recorder time, can also be specified. All information pertinent to the creation of a command schedule can be written to a file which is read by a command scheduler. The scheduler can be invoked and the Local Area Coverage (LAC) recording periods can be visually verified using CATLAC. The schedule can also be verified by examining record and error files written by the scheduler

The development and validation of command schedules for SeaWiFS

An automated method for developing and assessing spacecraft and instrument command schedules is presented for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) project. SeaWiFS is to be carried on the polar-orbiting SeaStar satellite in 1995. The primary goal of the SeaWiFS mission is to provide global ocean chlorophyll concentrations every four days by employing onboard recorders and a twice-a-day data downlink schedule. Global Area Coverage (GAC) data with about 4.5 km resolution will be used to produce the global coverage. Higher resolution (1.1 km resolution) Local Area Coverage (LAC) data will also be recorded to calibrate the sensor. In addition, LAC will be continuously transmitted from the satellite and received by High Resolution Picture Transmission (HRPT) stations. The methods used to generate commands for SeaWiFS employ numerous hierarchical checks as a means of maximizing coverage of the Earth's surface and fulfilling the LAC data requirements. The software code is modularized and written in Fortran with constructs to mirror the pre-defined mission rules. The overall method is specifically developed for low orbit Earth-observing satellites with finite onboard recording capabilities and regularly scheduled data downlinks. Two software packages using the Interactive Data Language (IDL) for graphically displaying and verifying the resultant command decisions are presented. Displays can be generated which show portions of the Earth viewed by the sensor and spacecraft sub-orbital locations during onboard calibration activities. An IDL-based interactive method of selecting and testing LAC targets and calibration activities for command generation is also discussed

The economic implications of HLA matching in cadaveric renal transplantation.

Abstract Background: The potential economic effects of the allocation of cadaveric kidneys on the basis of tissue-matching criteria are controversial. We analyzed the economic costs associated with the transplantation of cadaveric kidneys with various numbers of HLA mismatches and examined the potential economic benefits of a local, as compared with a national, system designed to minimize HLA mismatches between donor and recipient in first cadaveric renal transplantations. Methods: All data were supplied by the U.S. Renal Data System. Data on all payments made by Medicare from 1991 through 1997 for the care of recipients of a first cadaveric renal transplant were analyzed according to the number of HLA-A, B, and DR mismatches between donor and recipient and the duration of cold ischemia before transplantation. Results: Average Medicare payments for renal-transplant recipients in the three years after transplantation increased from $60,436 per patient for fully HLA-matched kidneys (those with no HLA-A, B, or DR mismatches) to$80,807 for kidneys with six HLA mismatches between donor and recipient, a difference of 34 percent (P\u3c0.001). By three years after transplantation, the average Medicare payments were $64,119 for transplantations of kidneys with less than 12 hours of cold-ischemia time and$74,997 for those with more than 36 hours (P\u3c0.001). In simulations, the assignment of cadaveric kidneys to recipients by a method that minimized HLA mismatching within a local geographic area (i.e., within one of the approximately 50 organ-procurement organizations, which cover widely varying geographic areas) produced the largest cost savings ($4,290 per patient over a period of three years) and the largest improvements in the graft-survival rate (2.3 percent) when the potential costs of longer cold-ischemia time were considered. Conclusions: Transplantation of better-matched cadaveric kidneys could have substantial economic advantages. In our simulations, HLA-based allocation of kidneys at the local level produced the largest estimated cost savings, when the duration of cold ischemia was taken into account. No additional savings were estimated to result from a national allocation program, because the additional costs of longer cold-ischemia time were greater than the advantages of optimizing HLA matching

The Neon Abundance in the Ejecta of QU Vul From Late-Epoch IR Spectra

We present ground-based SpectroCam-10 mid-infrared, MMT optical, and Spitzer Space Telescope IRS mid-infrared spectra taken 7.62, 18.75, and 19.38 years respectively after the outburst of the old classical nova QU Vulpeculae (Nova Vul 1984 #2). The spectra of the ejecta are dominated by forbidden line emission from neon and oxygen. Our analysis shows that neon was, at the first and last epochs respectively, more than 76 and 168 times overabundant by number with respect to hydrogen compared to the solar value. These high lower limits to the neon abundance confirm that QU Vul involved a thermonuclear runaway on an ONeMg white dwarf and approach the yields predicted by models of the nucleosynthesis in such events.Comment: ApJ 2007 accepted, 18 pages, including 5 figures, 1 tabl

A Spitzer IRAC Census of the Asymptotic Giant Branch Populations in Local Group Dwarfs. II. IC 1613

We present Spitzer Space Telescope IRAC photometry of the Local Group dwarf irregular galaxy IC 1613. We compare our 3.6, 4.5, 5.8, and 8.0 micron photometry with broadband optical photometry and find that the optical data do not detect 43% and misidentify an additional 11% of the total AGB population, likely because of extinction caused by circumstellar material. Further, we find that a narrowband optical carbon star study of IC 1613 detects 50% of the total AGB population and only considers 18% of this population in calculating the carbon to M-type AGB ratio. We derive an integrated mass-loss rate from the AGB stars of 0.2-1.0 x 10^(-3) solar masses per year and find that the distribution of bolometric luminosities and mass-loss rates are consistent with those for other nearby metal-poor galaxies. Both the optical completeness fractions and mass-loss rates in IC 1613 are very similar to those in the Local Group dwarf irregular, WLM, which is expected given their similar characteristics and evolutionary histories.Comment: Accepted by ApJ, 26 pages, 10 figures, version with high-resolution figures available at: http://webusers.astro.umn.edu/~djackson