Dual-output fs/ps burst-mode laser for megahertz-rate rotational coherent anti-Stokes Raman scattering.

A burst-mode laser system is developed for hybrid femtosecond/picosecond (fs/ps) rotational coherent anti-Stokes Raman scattering (RCARS) at megahertz rates. Using a common fs oscillator, the system simultaneously generates time synchronized 1061 nm, 274 fs and 1064 nm, 15.5 ps pulses with peak powers of 350 MW and 2.5 MW, respectively. The system is demonstrated for two-beam fs/ps RCARS in N2 at 1 MHz with a signal-to-noise ratio of 176 at room temperature. This repetition rate is an order of magnitude higher than previous CARS using burst-mode ps laser systems and two to three orders of magnitude faster than previous continuously pulsed fs or fs/ps laser systems.

Megahertz-rate shock-wave distortion cancellation via phase conjugate digital in-line holography.

Holography is a powerful tool for three-dimensional imaging. However, in explosive, supersonic, hypersonic, cavitating, or ionizing environments, shock-waves and density gradients impart phase distortions that obscure objects in the field-of-view. Capturing time-resolved information in these environments also requires ultra-high-speed acquisition. To reduce phase distortions and increase imaging rates, we introduce an ultra-high-speed phase conjugate digital in-line holography (PCDIH) technique. In this concept, a coherent beam passes through the shock-wave distortion, reflects off a phase conjugate mirror, and propagates back through the shock-wave, thereby minimizing imaging distortions from phase delays. By implementing the method using a pulse-burst laser setup at up to 5 million-frames-per-second, time-resolved holograms of ultra-fast events are now possible. This technique is applied for holographic imaging through laser-spark plasma-generated shock-waves and to enable three-dimensional tracking of explosively generated hypersonic fragments. Simulations further advance our understanding of physical processes and experiments demonstrate ultra-high-speed PCDIH techniques for capturing dynamics.

Compact burst-mode Nd:YAG laser for kHz-MHz bandwidth velocity and species measurements.

A compact-footprint (0.18 m2) flash-lamp-pumped, burst-mode Nd:YAG-based master-oscillator pulsed-amplifier laser is reported with a fundamental 1064 nm output of over 14 J per burst. A directly modulated diode laser seed source is used to generate 10 ms duration arbitrary sequences of 500 kHz doublet or MHz singlet pulses for flow-field velocity or species measurements, respectively. Flexible pulse widths are used to balance the energy distribution of pulse doublets and achieve second-harmonic conversion efficiencies up to 42%. Burst-mode laser performance characteristics, measurement accuracies in turbulent flows, and prospects for kHz-MHz flow-field diagnostics are discussed.

Changes in awareness and use of calorie information after mandatory menu labeling in restaurants in King County, Washington.

OBJECTIVES: We examined population-level impact on customer awareness and use and explored potential disparities in outcomes regarding the King County, Washington, regulation requiring chain restaurants to provide calorie information. METHODS: We analyzed 2008 to 2010 Behavioral Risk Factor Surveillance System data from 3132 English-speaking King County residents aged 18 years and older who reported eating at a regulated chain. We used regression models to assess changes in calorie information awareness and use from prepolicy to postpolicy implementation by customer demographics, health status, and restaurant type. RESULTS: Calorie information awareness and use increased significantly from 2008 to 2010. Unadjusted analyses indicated that the proportion who saw and used calorie information tripled, from 8.1% to 24.8%. Fully adjusted analyses confirmed significant increases. After policy implementation, White, higher income, and obese respondents had greater odds of seeing calorie information. Women, higher income groups, and those eating at a fast-food versus a sit-down chain restaurant were more likely to use this information. CONCLUSIONS: Significant increases in calorie information awareness and use following regulation support the population-wide value of this policy. However, improvements varied across race, income, and gender.

The impact of a community-based chronic disease prevention initiative: evaluation findings from Steps to Health King County.

Steps to Health King County (Steps KC; Seattle, Washington) was one of 40 community-level initiatives funded in 2003 as part of the Steps to a HealthierUS initiative. Steps KC goals included reducing the impact of chronic diseases through a comprehensive, coordinated approach and reducing health disparities due to chronic illness. Steps KC intervention activities took place on two levels: the overall Steps KC collaborative and individual funded programs. Collaborative-level activities included policy and systems change initiatives and efforts to better integrate the funded-program organizations. The funded programs ranged from group health promotion programs to intensive case management. Steps KC was successful in creating a large, diverse community collaborative and funding 14 separate programs that reached approximately 8,000 community residents with medium- and high-intensity programs of demonstrated effectiveness. Systems change initiatives within school districts and government agencies led to a greater institutional emphasis on health promotion and on partnership with communities to address health inequities.

A nationwide population-based study identifying health disparities between American Indians/Alaska Natives and the general populations living in select urban counties.

OBJECTIVES: Despite their increasing numbers, little is known about the health of American Indians/Alaska Natives living in urban areas. We examined the health status of American Indian/Alaska Native populations served by 34 federally funded urban Indian health organizations. METHODS: We analyzed US census data and vital statistics data for the period 1990 to 2000. RESULTS: Disparities were revealed in socioeconomic, maternal and child health, and mortality indicators between American Indians/Alaska Natives and the general populations in urban Indian health organization service areas and nationwide. American Indians/Alaska Natives were approximately twice as likely as these general populations to be poor, to be unemployed, and to not have a college degree. Similar differences were observed in births among mothers who received late or no prenatal care or consumed alcohol and in mortality attributed to sudden infant death syndrome, chronic liver disease, and alcohol consumption. CONCLUSIONS: We found health disparities between American Indians/Alaska Natives and the general populations living in selected urban areas and nationwide. Such disparities can be addressed through improvements in health care access, high-quality data collection, and policy initiatives designed to provide sufficient resources and a more unified vision of the health of urban American Indians/Alaska Natives.