Mode-locking in advection-reaction-diffusion systems: an invariant manifold perspective

Fronts propagating in two-dimensional advection-reaction-diffusion (ARD) systems exhibit rich topological structure. When the underlying fluid flow is periodic in space and time, the reaction front can lock to the driving frequency. We explain this mode-locking phenomenon using so-called burning invariant manifolds (BIMs). In fact, the mode-locked profile is delineated by a BIM attached to a relative periodic orbit (RPO) of the front element dynamics. Changes in the type (and loss) of mode-locking can be understood in terms of local and global bifurcations of the RPOs and their BIMs. We illustrate these concepts numerically using a chain of alternating vortices in a channel geometry.Comment: 9 pages, 13 figure

Personnel techniques necessary to maximize bio-barrier integrity at a Martian receiving laboratory

The planning of biological isolation measures for the Mars Surface Sample Return Mission is discussed in terms of personnel and organizational management. Deficiencies in past operation of the Lunar Receiving Laborator are analyzed. It was found that the failure to clearly define relationship among the government agencies involved and to effectively integrate their objectives and responsibilities was a major cause of Laboratory deficiencies. Possible solutions to these problems are presented for application to future missions

Current Approaches to Improving the Value of Care: A Physician's Perspective

Evaluates the utility of judgment-based approaches to quality improvement -- pay-for-performance, public reporting, consumer-directed health plans, and tiering -- as ways to control costs. Recommends incentive- and accountability-based programs

HEAO 3 upper limits to the expected 1634 KeV line from SS 483

A model based on 24 Mg(1369) was developed as the source of the lines in which refractory grains in the jets, containing Mg and 0, are bombarded, by ambient protons in the local ISM. The narrowness of the features results because the recoil Mg nucleus is stopped in the grain before the 1369 keV excited state decays. A consequence of the 24 Mg interpretation is the expected appearance of other emission lines, due to 20 Ne and 20 Na, which are produced by proton bombardment of 24 Mg at the 33 MeV/nucleon energy corresponding to the velocity of the jets. These lines appear at rest energies of 1634 keV and 1636 keV, respectively, and should have essentially the same total flux as that emited at 1369 keV. The HEAO 3 data are examined to search for the 1634 keV (rest) emission. The observation and analysis, the results, and the implications for the understanding of SS 433 are discussed

High-resolution spectrum of Cygnus X-1

A high resolution spectrum of Cygnus X-1 in the 45 to 600 keV range is presented. The measurement was made by the HEAO 3 gamma ray spectrometer during 82 days in the fall of 1979 and spring of 1980, when the source was in its normal low state. Results of a search for narrow emission lines from the source are reported. The spectrum shows no significant narrow features. The 3 delta upper limit to a narrow 511 keV annihilation line is 3 x 0.0001 photons/sq cm/s. There is also no evidence in HEAO 3 broadband data above 500 keV for the broad annihilation feature observed by HEAO 1

GaAs monolithic frequency doublers with series connected varactor diodes

GaAs monolithic frequency doublers using series connected varactor diodes have been fabricated for the first time. Output powers of 150 mW at 36.9 GHz with 24% efficiency and 300 mW at 24.8 GHz with 18% efficiency have been obtained. Peak efficiencies of 35% at output power levels near 100 mW have been achieved at both frequencies. Both K-band and Ka-band frequency doublers are derived from a lower power, single-diode design by series connection of two diodes and scaling to achieve different power and frequency specifications. Their fabrication was accomplished using the same process sequence

Secure attachments and how they promote resilience in children of alcoholics

Children of alcoholics (COAs) experience risk factors including difficulties in school, behavioral issues, psychological distress, and the potential to become a substance abuser themselves. However, there is also research to support that not all COAs experience negative outcomes as a result of their alcoholic parent\u27s influence. This qualitative study sought to explore whether positive attachments promote resilience in COAs from the perspective of COAs themselves. Semi-structured interviews were conducted with nine participants who were COAs and could identify a positive attachment relationship from the time period when they lived with their alcoholic parent(s). The major finding of this study was that, while having a positive, secure attachment was beneficial in promoting resilience, it was not enough to mitigate all potential negative consequences COAs experience. Implications of this finding for future research and social work practice are discussed