An Understanding of the Shoulder of Giants: Jovian Planets around Late K Dwarf Stars and the Trend with Stellar Mass

Analyses of exoplanet statistics suggest a trend of giant planet occurrence with host star mass, a clue to how planets like Jupiter form. One missing piece of the puzzle is the occurrence around late K dwarf stars (masses of 0.5-0.75Msun and effective temperatures of 3900-4800K). We analyzed four years of Doppler radial velocities data of 110 late K dwarfs, one of which hosts two previously reported giant planets. We estimate that 4.0+/-2.3% of these stars have Saturn-mass or larger planets with orbital periods <245d, depending on the planet mass distribution and RV variability of stars without giant planets. We also estimate that 0.7+/-0.5% of similar stars observed by Kepler have giant planets. This Kepler rate is significantly (99% confidence) lower than that derived from our Doppler survey, but the difference vanishes if only the single Doppler system (HIP 57274) with completely resolved orbits is considered. The difference could also be explained by the exclusion of close binaries (without giant planets) from the Doppler but not Kepler surveys, the effect of long-period companions and stellar noise on the Doppler data, or an intrinsic difference between the two populations. Our estimates for late K dwarfs bridge those for solar-type stars and M dwarfs and support a positive trend with stellar mass. Small sample size precludes statements about finer structure, e.g. a "shoulder" in the distribution of giant planets with stellar mass. Future surveys such as the Next Generation Transit Survey and the Transiting Exoplanet Satellite Survey will ameliorate this deficiency.Comment: Accepted to The Astrophysical Journa

GETTING TECHNOLOGY AND THE TECHNOLOGY ENVIRONMENT RIGHT: LESSONS FROM MAIZE DEVELOPMENT IN SOUTHERN AFRICA

This paper examines two questions: (1) what were the most important factors that led to differential rates of adoption of maize technology by farmers in Zimbabwe, Zambia, and Malawi from 1910 to 1995? and (2) what do these experiences suggest about strategic investments in institutions and organizations needed to create a sustainable environment for technology development and adoption in the future? The analysis suggests that productivity increases are facilitated by (a) technology innovations throughout the agricultural system, (b) integration of technological innovations with changes in policies, organizations, human capital and infrastructure related to extension, input and output markets and processing services, and (c) coordination of these innovations across different stages of the agricultural system.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

FINANCIAL AND RISK ANALYSIS OF MAIZE TECHNOLOGY IN ETHIOPIA, BASED ON CERES-MAIZE MODEL RESULTS

This paper presents a financial and risk analysis of improved versus traditional maize production technology in Ethiopia, based on yields simulated with the CERES-Maize crop growth model (Schulthess and Ward, 2000). The purpose is to analyze the potential performance of the SG2000/Ministry of Agriculture program technology under less favorable meteorological conditions (rainfall level and distribution), and in areas with lower agroecological potential than those covered by the SG2000/MOA program through 1998. At the time of this study, expansion of the MOA program into lower potential zones seemed likely. Results show that use of fertilizer and improved seed is highly profitable under a variety of assumptions about crop growth conditions, maize prices, and fertilizer costs. Risk is examined using simple sensitivity and breakeven analysis, and stochastic dominance analysis.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets

We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative on an additional planetary companion. We confirm that GJ 849 is a multi-planet system and find a good orbital solution for the c component: it is a $1 M_{\rm Jup}$ planet in a 15 yr orbit (the longest known for a planet orbiting an M dwarf). We update the HD 74156 double-planet system. We also announce the detection of HD 145934 b, a $2 M_{\rm Jup}$ planet in a 7.5 yr orbit around a giant star. Two of our stars, HD 187123 and HD 217107, at present host the only known examples of systems comprising a hot Jupiter and a planet with a well constrained period $> 5$ yr, and with no evidence of giant planets in between. Our enlargement and improvement of long-period planet parameters will aid future analysis of origins, diversity, and evolution of planetary systems.Comment: 16 pages, 13 figures. Accepted for publication in Ap

The TRENDS High-Contrast Imaging Survey. VI. Discovery of a Mass, Age, and Metallicity Benchmark Brown Dwarf

The mass and age of substellar objects are degenerate parameters leaving the evolutionary state of brown dwarfs ambiguous without additional information. Theoretical models are normally used to help distinguish between old, massive brown dwarfs and young, low mass brown dwarfs but these models have yet to be properly calibrated. We have carried out an infrared high-contrast imaging program with the goal of detecting substellar objects as companions to nearby stars to help break degeneracies in inferred physical properties such as mass, age, and composition. Rather than using imaging observations alone, our targets are pre-selected based on the existence of dynamical accelerations informed from years of stellar radial velocity (RV) measurements. In this paper, we present the discovery of a rare benchmark brown dwarf orbiting the nearby ($d=18.69\pm0.19$ pc), solar-type (G9V) star HD 4747 ([Fe/H]=$-0.22\pm0.04$) with a projected separation of only $\rho=11.3\pm0.2$ AU ($\theta \approx$ 0.6"). Precise Doppler measurements taken over 18 years reveal the companion's orbit and allow us to place strong constraints on its mass using dynamics ($m \sin(i) = 55.3\pm1.9M_J$). Relative photometry ($\Delta K_s=9.05\pm0.14$, $M_{K_s}=13.00\pm0.14$, $K_s - L' = 1.34\pm0.46$) indicates that HD 4747 B is most-likely a late-type L-dwarf and, if near the L/T transition, an intriguing source for studying cloud physics, variability, and polarization. We estimate a model-dependent mass of $m=72^{+3}_{-13}M_J$ for an age of $3.3^{+2.3}_{-1.9}$ Gyr based on gyrochronology. Combining astrometric measurements with RV data, we calculate the companion dynamical mass ($m=60.2\pm3.3M_J$) and orbit ($e=0.740\pm0.002$) directly. As a new mass, age, and metallicity benchmark, HD 4747 B will serve as a laboratory for precision astrophysics to test theoretical models that describe the emergent radiation of brown dwarfs.Comment: Accepted to Ap

Chromospheric Activity of HAT-P-11: an Unusually Active Planet-Hosting K Star

Kepler photometry of the hot Neptune host star HAT-P-11 suggests that its spot latitude distribution is comparable to the Sun's near solar maximum. We search for evidence of an activity cycle in the CaII H & K chromospheric emission $S$-index with archival Keck/HIRES spectra and observations from the echelle spectrograph on the ARC 3.5 m Telescope at APO. The chromospheric emission of HAT-P-11 is consistent with a $\gtrsim 10$ year activity cycle, which plateaued near maximum during the Kepler mission. In the cycle that we observed, the star seemed to spend more time near active maximum than minimum. We compare the $\log R^\prime_{HK}$ normalized chromospheric emission index of HAT-P-11 with other stars. HAT-P-11 has unusually strong chromospheric emission compared to planet-hosting stars of similar effective temperature and rotation period, perhaps due to tides raised by its planet.Comment: 16 pages, 8 figures; accepted to the Astrophysical Journa

PROGRESS AND PROBLEMS IN PROMOTING HIGH EXTERNAL-INPUT TECHNOLOGIES IN SUB-SAHARAN AFRICA: THE SASAKAWA GLOBAL 2000 EXPERIENCE IN ETHIOPIA AND MOZAMBIQUE

Critics argue that high external input technologies are too costly for African farmers, and that pilot programs to promote them are economically unsustainable. This paper assesses Sasakawa-Global 2000 programs in Ethiopia and Mozambique; budgets, yield models and subsector analysis help explain the radically different country results and prognoses for sustainable adoption.technology adoption, sub-Saharan Africa, Sasakawa-Global 2000, maize, fertilizer, International Development, Research and Development/Tech Change/Emerging Technologies, O002, O003,

Green Revolution Technology Takes Root in Africa The Promise and Challenge of the Ministry of Agriculture/SG2000 Experiment with Improved Cereals Technology in Ethiopia

In 1993, the Sasakawa/Global 2000 Program (SG) and the Ministry of Agriculture (MOA) began a joint program to demonstrate that substantial productivity increases could be achieved when farmers were given appropriate extension messages and agricultural inputs were delivered on time at reasonable prices. The program provided credit, inputs and extension assistance to participants willing to establish half-hectare demonstration plots on their own land. In 1995, the MOA/SG demonstration program reached more than 3,500 farmers. During the same year MOA launched the New Extension Program (NEP) based on SG principles but managed independently. By 1997, NEP was managing the bulk of the demonstration plots. Although the MOA/SG program is widely considered to be a success, no formal analysis had been carried out to determine its profitability. In September 1997 MOA/SG agreed to collaborate with MSU to answer the following questions: (1) Is improved technology financially profitable for farmers? (2) Is it economically profitable from a national perspective? (3) What factors limit crop response to improved technologies? and (4) What challenges does the government face as it scales up the NEP program?food security, food policy, agricultural inputs, Ethiopia, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies, Downloads July 2008 - June 2009: 15, O33,

Green Revolution Technology Takes Root In Africa: The Promise and Challenge of the Ministry of Agriculture/SG2000 Experiment with Improved Cereals Technology in Ethiopia; Statistical Annex and Copies of Questionnaire

food security, food policy, agricultural inputs, Ethiopia, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies, Downloads July 2008 - July 2009: 5, O33,