Showing papers by "Charles L. Bennett published in 1992"

Structure in the COBE differential microwave radiometer first year maps

Abstract: Results of the first year of data from the differential microwave radiometers on the Cosmic Background Explorer are presented. Statistically significant structure that is well described as scale-invariant fluctuations with a Gaussian distribution is shown. The rms sky variation, smoothed to a total 10-deg FWHM Gaussian, is 30 +/-5 micro-K for Galactic latitude greater than 20-deg data with the dipole anisotropy removed. The rms cosmic quadrupole amplitude is 13 +/-4 micro-K. The angular autocorrelation of the signal in each radiometer channel and cross-correlation between channels are consistent and give a primordial fluctuation power-law spectrum with index of 1.1 +/-0.5, and an rms-quadrupole-normalized amplitude of 16 +/-4 micro-K. These features are in accord with the Harrison-Zel'dovich spectrum predicted by models of inflationary cosmology.

The COBE Mission: Its Design and Performance Two Years after Launch

Abstract: The COBE mission, NASA's first space mission devoted primarily to cosmology, is described and the spacecraft concepts central to enabling the mission to achieve its scientific objectives are examined. The major components of the COBE instrument and spacecraft modules are shown and their characteristics are given. Early scientific results are summarized and plans for continuing satellite operations and data analysis are addressed.

Interpretation of the Cosmic Microwave Background radiation anisotropy detected by the COBE differential microwave radiometer

Abstract: The large-scale cosmic background anisotropy detected by the COBE Differential Microwave Radiometer (DMR) instrument is compared to the sensitive previous measurements on various angular scales, and to the predictions of a wide variety of models of structure formation driven by gravitational instability. The observed anisotropy is consistent with all previously measured upper limits and with a number of dynamical models of structure formation. For example, the data agree with an unbiased cold dark matter (CDM) model with H0 = 50 km/s Mpc and Delta-M/M = 1 in a 16 Mpc radius sphere. Other models, such as CDM plus massive neutrinos (hot dark matter (HDM)), or CDM with a nonzero cosmological constant are also consistent with the COBE detection and can provide the extra power seen on 5-10,000 km/s scales.

Comparison of Emission Inventory and Ambient Concentration Ratios of CO, NMOG, and NOx in California's South Coast Air Basin

Abstract: In the present study, we performed a "top-down" validation of the reactive organic gas and carbon monoxide emission inventories for California's South Coast Air Basin by comparing speciation profiles for nonmethane organic gases (NMOG) and ratios of CO/NOx and NMOG/NOx derived from early-morning (0700 to 0800) ambient measurements taken during the 1987 Southern California Air Quality Study with the corresponding ratios and speciation profiles derived from day-specific, hourly, gridded emission inventories. We considered twenty separate comparisons for each ratio, each representing a different combination of season, emission category, and spatial and temporal averaging of emissions. We determined that the most appropriate comparison in summer was ambient pollutant ratios with ratios derived from morning on-road motor vehicle emission inventories, and in the fall, ambient ratios with ratios derived from overnight on-road motor vehicle emission inventories with some contribution from overnight stationary-sou...

COBE Differential Microwave Radiometers - Preliminary systematic error analysis

Abstract: The techniques available for the identification and subtraction of sources of dynamic uncertainty from data of the Differential Microwave Radiometer (DMR) instrument aboard COBE are discussed. Preliminary limits on the magnitude in the DMR 1 yr maps are presented. Residual uncertainties in the best DMR sky maps, after correcting the raw data for systematic effects, are less than 6 micro-K for the pixel rms variation, less than 3 micro-K for the rms quadruple amplitude of a spherical harmonic expansion, and less than 30 micro-(K-squared) for the correlation function.

COBE differential microwave radiometers - Calibration techniques

Abstract: The COBE spacecraft was launched November 18, 1989 UT carrying three scientific instruments into earth orbit for studies of cosmology. One of these instruments, the Differential Microwave Radiometer (DMR), is designed to measure the large-angular-scale temperature anisotropy of the cosmic microwave background radiation at three frequencies (31.5, 53, and 90 GHz). This paper presents three methods used to calibrate the DMR. First, the signal difference between beam-filling hot and cold targets observed on the ground provides a primary calibration that is transferred to space by noise sources internal to the instrument. Second, the moon is used in flight as an external calibration source. Third, the signal arising from the Doppler effect due to the earth's motion around the barycenter of the solar system is used as an external calibration source. Preliminary analysis of the external source calibration techniques confirms the accuracy of the currently more precise ground-based calibration. Assuming the noise source behavior did not change from the ground-based calibration to flight, a 0.1-0.4 percent relative and 0.7-2.5 percent absolute calibration uncertainty is derived, depending on radiometer channel.

Measurement of the LMM dielectronic recombination resonances of neonlike gold.

Abstract: The {ital LMM} dielectronic recombination resonances of a neonlike ion (Au{sup 69+}) have been observed. The ions were produced and held in an electron-beam ion trap. The intensity of the {ital n}=3{r arrow}2 x rays resulting from dielectronic recombination was measured as a function of electron-beam energy with sufficient resolution to distinguish the structure of the {ital LMM} resonances. The measured resonance strengths for {ital LMM} resonances with a 2{ital p}{sub 3/2}{sup {minus}1} core are in good agreement with theoretical predictions, but there is some disagreement for the 2{ital p}{sub 1/2}{sup {minus}1} and 2{ital s}{sub 1/2}{sup {minus}1} core configurations.

Health care in the Czech Republic. A system in transition.

Abstract: This article discusses the health care reforms currently taking place in the Czech Republic which began after the collapse of the Communist regime in the fall of 1989. Since 1968 the 2 republics which make up the Czech Slovak Federative Republic (CSFR) have administered their health care systems separately. This article focuses only on health care in the Czech Republic examining the following issues: 1) health status; 2) health care providers resources and expenditures; 3) health care system history and current reform; 4) health care financing; 5) health services; 6) environmental and public health; and 7) the monitoring of the new health care system. The Czech Slovak Federative Republics (CSFR) overall state of health has lagged behind that of Western countries. Mortality rates for example are comparable to those found in the United Kingdom and West Germany in the 1950s. In the CSFR abortion is widespread while contraceptive use is low. In 1989 a group of specialists launched a campaign to bring health care reform to the Czech Republic; the government approved the groups recommendations the following year. The reforms are based on the following principles: universal access; greater freedom of choice for patients; multiple sources of financing; decentralization and demonopolization; public and private sector cooperation; increased autonomy of health care providers; and emphasis on ambulatory care disease prevention and health promotion. The new health care system will include both government and private sector monitoring mechanisms.

SO in Starburst Galaxies

Abstract: The use of SO and SO2 as probes of the dense interstellar medium in the nearby starburst galaxies NGC 253 and M82 is described. Emission in the 99.3 GHz 3(2) - 2(1) rotational transition of SO was detected in NGC 253 and possibly in M82, and upper limits are reported for emission in the 219.9 GHz 6(5) - 5(4) transition of SO and two lines of SO2. The column density of SO relative to carbon sulfide, CS, is more than 0.08 in NGC 253, a value not much lower than Galactic ratios and consistent with models of dense interstellar clouds with a fractional abundance of atomic oxgyen greater than about 10 exp -7. The 218.8 GHz 3(21) - 2(20) transition of para-formaldehyde, with an excitation temperature of 68 K, was also detected in NGC 253.

COBE Differential Microwave Radiometer (DMR) data processing techniques

Abstract: The purpose of the Differential Microwave Radiometer (DMR) experiment on the Cosmic Background Explorer (COBE) satellite is to make whole-sky maps, at frequencies of 31.5, 53, and 90 GHz, of any departures of the Cosmic Microwave Background (CMB) from its mean value of 2.735 K. An elaborate software system is necessary to calibrate and invert the differential measurements, so as to make sky maps free from large scale systematic errors to levels less than a millionth of the CMB.