271 research outputs found

    A Guatemalan Soycow Cooperative: Is the Whole Greater than the Sum of its Parts?

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    Teaching Notes available upon request: [email protected]; Author video:http://www.youtube.com/user/ifamr1?feature=mhum#p/u/8/FhUZu2lt6NsSoycow, cooperative, Guatemala, teaching case, Agribusiness, Q10,

    Physical Function in Young and Older Adult Active Pickleball Players

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    Limited information exists on pickleball’s impact on physical function in adults, especially older adults (65+ years), despite reported health benefits. PURPOSE: This study evaluated the physical function of active older adult (OA) female and male recreational pickleball players via handgrip strength and fatigue, 6-minute walk distance (6MWD) test, as well as the short physical performance battery (SPPB) compared to sex-matched young adult (YA) controls. METHODS: Thirty YA (18-26 years; n=15 female/male) participants and 27 OA (65-89 years; n=13 female, n=15 male) participants who played pickleball at least three times per week were assessed for physical function outcomes of handgrip strength (HGS) and fatigue (HGF), 6-minute walk distance (6MWD), and the short physical performance battery (SPPB). A two-way ANOVA (age x sex) with repeated measures and Sidak post-hoc test were used (pRESULTS: Compared to sex-matched YA, OA women and men had significantly (p2). Absolute HGF followed the absolute HGS results. In contrast, compared to sex-matched YA, no significant differences (p\u3e0.05) were observed in OA women and men for 6MWD percent predicted (which factored in anthropometrics, age, gender, and activity levels; range: 104.6-115.4%) and the overall SPPB (range: 11.3-12.0) as well as each portion of the SPPB (balance, gait speed, and lower limb strength). CONCLUSION: In OA female and male recreational pickleballers, lower body physical function (e.g., walking speed/distance, balance, lower body strength) is largely maintained compared to sex-matched YA pickleballers, but upper body strength/fatigue were not. Pickleball should be combined with meeting resistance training guidelines to maintain whole body physical function with aging

    The HD 192263 system: planetary orbital period and stellar variability disentangled

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    As part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS), we present new radial velocities and photometry of the HD 192263 system. Our analysis of the already available Keck-HIRES and CORALIE radial velocity measurements together with the five new Keck measurements we report in this paper results in improved orbital parameters for the system. We derive constraints on the size and phase location of the transit window for HD 192263b, a Jupiter-mass planet with a period of 24.3587 \pm 0.0022 days. We use 10 years of Automated Photoelectric Telescope (APT) photometry to analyze the stellar variability and search for planetary transits. We find continuing evidence of spot activity with periods near 23.4 days. The shape of the corresponding photometric variations changes over time, giving rise to not one but several Fourier peaks near this value. However, none of these frequencies coincides with the planet's orbital period and thus we find no evidence of star-planet interactions in the system. We attribute the ~23-day variability to stellar rotation. There are also indications of spot variations on longer (8 years) timescales. Finally, we use the photometric data to exclude transits for a planet with the predicted radius of 1.09 RJ, and as small as 0.79 RJ.Comment: 9 pages, 6 tables, 6 figures; accepted to Ap

    Retired A Stars and Their Companions VI. A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD200964

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    We report radial velocity measurements of the G-type subgiants 24 Sextanis (=HD90043) and HD200964. Both are massive, evolved stars that exhibit periodic variations due to the presence of a pair of Jovian planets. Photometric monitoring with the T12 0.80m APT at Fairborn Observatory demonstrates both stars to be constant in brightness to <= 0.002 mag, thus strengthening the planetary interpretation of the radial velocity variations. 24 Sex b,c have orbital periods of 453.8 days and 883~days, corresponding to semimajor axes 1.333 AU and 2.08 AU, and minimum masses (Msini) 1.99 Mjup and 0.86 Mjup, assuming a stellar mass 1.54 Msun. HD200964 b,c have orbital periods of 613.8 days and 825 days, corresponding to semimajor axes 1.601 AU and 1.95 AU, and minimum masses 1.85 Mjup and 0.90 Mjup, assuming M* = 1.44 Msun. We also carry out dynamical simulations to properly account for gravitational interactions between the planets. Most, if not all, of the dynamically stable solutions include crossing orbits, suggesting that each system is locked in a mean motion resonance that prevents close encounters and provides long-term stability. The planets in the 24 Sex system likely have a period ratio near 2:1, while the HD200964 system is even more tightly packed with a period ratio close to 4:3. However, we caution that further radial velocity observations and more detailed dynamical modelling will be required to provide definitive and unique orbital solutions for both cases, and to determine whether the two systems are truly resonant.Comment: AJ accepte
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