Center-Oriented Aiming Strategy for Heliostat with Spinning-Elevation Tracking Method

Spinning-Elevation (SE) tracking system produces a decent image on the receiver surface; however, it is subjected to large variations in tracking speed. In this research, a Graphical Ray Tracing (GRT) model for Center-Oriented Spinning-Elevation (COSE) tracking method is developed to evaluate tracking angles. Instead of a target, a heliostat is pointed towards the on-field center point of the tower. Therefore, a spinning-axis of rotation is a line joining a heliostat, and a center of the tower and elevation-axis is perpendicular to it. This aiming strategy has shown a substantial reduction in rotations of spinning-motor. In contrast, the elevation-motor runs at slightly higher rotations than the target-oriented SE method for the same application. Also, COSE tracking method obtains better shape of the reflected image with less aberration on the receiver surface as compared to SE and the traditional Azimuth-Elevation (AE) method.

A Selective History of the Jet Propulsion Laboratory

The Jet Propulsion Laboratory (JPL) of the California Institute of Technology had its origins in a student project to develop rocket propulsion in the late 1930s. It attracted funding from the U.S. Army just prior to U.S. entry into World War II and became an Army missile research facility in 1943. Because of its origins as a contractor-operated Army research facility, JPL is the National Aeronautics and Space Administration’s (NASA) only contractor-operated field center. It remains a unit of the California Institute of Technology. In the decades since its founding, the laboratory, first under U.S. Army direction and then as a NASA field center, has grown and evolved into an internationally recognized institution generally seen as a leader in solar system exploration but whose portfolio includes substantial Earth remote sensing. JPL’s history includes episodes where the course of the laboratory’s development took turning points into new directions. After developing short-range ballistic missiles for the Army, the laboratory embarked on a new career in lunar and planetary exploration through the early 1970s and abandoned its original purpose as a propulsion technology laboratory. It developed the telecommunications infrastructure for planetary exploration too. It diversified into Earth science and astrophysics in the late 1970s and, due to a downturn in funding for planetary exploration, returned to significant amounts of defense work in the 1980s. The end of the Cold War between 1989 and 1991 resulted in a declining NASA budget, but support for planetary exploration actually improved within NASA management—as long as that exploration could be done more cheaply. This resulted in what is known as the “Faster Better Cheaper” period in NASA history. For JPL, this ended in 2000, succeeded by a return to more rigorous technical standards and increased costs.

Epidemiology of Perceived Physical Fatigability in Older Adults: The Long Life Family Study

Background Fatigability is a construct that measures whole-body tiredness anchored to activities of a fixed intensity and duration; little is known about its epidemiology and heritability. Methods Two generations of family members enriched for exceptional longevity and their spouses were enrolled (2006–2009) in the Long Life Family Study (LLFS). At Visit 2 (2014–2017, N = 2,355) perceived physical fatigability was measured using the 10-item self-administered Pittsburgh Fatigability Scale (PFS), along with demographic, medical, behavioral, physical, and cognitive risk factors. Results Residual genetic heritability of fatigability was 0.263 (p = 6.6 × 10–9) after adjustment for age, sex, and field center. PFS physical scores (mean ± SD) and higher physical fatigability prevalence (% PFS ≥ 15) were greater with each age strata: 60–69 (n = 1,009, 11.0 ± 7.6, 28%), 70–79 (n = 847, 12.5 ± 8.1, 37%), 80–89 (n = 253, 19.3 ± 9.9, 65.2%), and 90–108 (n = 266, 28.6 ± 9.8, 89.5%), p < .0001, adjusted for sex, field center, and family relatedness. Women had a higher prevalence of perceived physical fatigability compared to men, with the largest difference in the 80–89 age strata, 74.8% versus 53.5%, p < .0001. Those with greater body mass index, worse physical and cognitive function, and lower physical activity had significantly higher perceived physical fatigability. Conclusions Perceived physical fatigability is highly prevalent in older adults and strongly associated with age. The family design of LLFS allowed us to estimate the genetic heritability of perceived physical fatigability. Identifying risk factors associated with higher perceived physical fatigability can inform the development of targeted interventions for those most at risk, including older women, older adults with depression, and those who are less physically active.

PREVALENCE AND HERITABILITY OF PERCEIVED MENTAL FATIGABILITY IN THE LONG LIFE FAMILY STUDY

We examined the prevalence and heritability of perceived mental fatigability among older adults enrolled in the Long Life Family Study. Participants (N=2342; 55% female) self-administered the Pittsburgh Fatigability Scale (PFS; scores range 0-50; higher score=greater fatigability). Using the PFS mental subscale, we evaluated differences across age strata (adjusted for family structure and field center) and estimated genetic heritability using the variance covariance methods implemented in SOLAR to determine genetic heritability (adjusted for age, sex, and field center). PFS mental score (mean±SD) and prevalence of higher mental fatigability (PFS ≥13) was greater across age strata: 60-69 (N=996, 5.9± 6.5, 14.5%), 70-79 (N=830, 6.8 ±7.6, 18.7%), 80-89 (N=251, 11.7±10.8, 41.8%), and ≥90 (N=265, 20.2±13.6, 67.2%), p<0.0001. Only among those ≥90, females (21.7±13.5) had greater mental fatigability than males (18.0±13.5), p=0.03. Residual heritability of mental fatigability was 0.17, p<0.0001. Future analyses will evaluate correlates of mental fatigability to identify potential avenues for intervention.