2,991 research outputs found

    Follow the leader or the pack? Regulatory focus and academic entrepreneurial intentions

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    Drawing on the academic entrepreneurship and regulatory focus theory literature, and applying a multilevel per- spective, this paper examines why university academics intend to engage in formal (spin-off or start-up companies and licensing university research) or informal (collaborative research, contract research, continuous professional development, and contract consulting) commercialization activities and the role local contextual factors, in partic- ular leaders and work-group colleagues (peers), play in their commercialization choices. Based on a survey of 395 science, technology, engineering, and mathematics (STEM) academics working in 14 Scottish universities, the research findings suggest that an individual’s chronic regulatory focus has a direct effect on their formal and informal commercialization intent. The results reveal that the stronger an individual’s chronic promotion focus the stronger their formal and informal commercialization intentions and a stronger individual chronic prevention focus leads to weaker intentions to engage in informal commercialization. In addition, when contextual interaction effects are considered, leaders and workplace colleagues have different influences on commercialization intent. On the one hand, promotion-focused leaders can strengthen and prevention-focused leaders can under certain cir- cumstances weaken a promotion-focused academic’s formal commercialization intent. On the other hand, the level of workplace colleague engagement, acting as a reference point, strengthens not only promotion-focused academ- ics’ intent to engage in formal commercialization activities, but also prevention-focused academics’ corresponding informal commercialization intent. As such, universities should consider the appointment of leaders who are strong role models and have a track record in formal and/or informal commercialization activities and also con- sider the importance workplace colleagues have on moderating an academic’s intention to engage in different forms of commercialization activities

    Landscape-scale investigation into the risk of lodgepole pine mortality caused by mountain pine beetle Dendroctonus ponderosae (Coleoptera: Curculioidae: Scolytinae), A

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    2010 Fall.Includes bibliographical references.Mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, is currently causing Pinus contorta Douglas (LP) mortality in several areas of western United States and Canada at high levels including portions of Colorado. For decades, researchers have developed models to help land managers predict when and where MPB infestation will develop based on forest structure, tree size, tree age and geographic characteristics; these models were developed at the stand-level for stand-level analysis. Land managers and planners have become increasingly interested in predicting MPB risk and susceptibility at the landscape-scale; however attempts at landscape-scale modeling have proven difficult as continuous forest mensuration datasets are often lacking. Techniques for producing low-cost, high-resolution, landscape-scale forest composition and forest structure Geographic Information System (GIS) layers were demonstrated by this study. These GIS layers were subsequently used to assess several existing MPB risk models, at the landscape-scale, and to derive a new empirical MPB model. The procedures outlined in this paper describe the generation of landscape-scale forest composition and structure GIS layers (predictive surfaces) based on recent and innovative remote sensing and spatial statistical techniques. These techniques transform a small field sample into a continuous GIS surface utilizing multiple linear regression and binary regression trees. Information derived from satellite imagery and digital elevation models are used as auxiliary variables to assist in the prediction of response variables (basal area, proportion of lodgepole pine basal area, diameter at breast height, quadratic mean diameter, percent canopy closure, and trees per acre). A carefully designed field sample, stratified by Landsat image spectral groupings, optimized sampling faculties by maximizing between-stratum variability while minimizing within-stratum variability. Forest composition (spatial distribution of tree species), basal area, proportion of lodgepole pine basal area, diameter at breast height, quadratic mean diameter, percent canopy closure, and trees per acre predictive surfaces were developed for Colorado's Fraser River Valley. These predictive surfaces were then used to assess the landscape-scale predictive capabilities of following MPB prediction models: Anhold et al., (1996), Amman et al. (1977), Shore and Safranyik (1992), and the USDA Forest Service National Insect and Disease Risk Map. Finally, a new MPB model is described based on geographic factors, the predictive surfaces, and recent occurrence of mountain pine beetle caused-tree mortality

    The California-Kepler Survey. IV. Metal-rich Stars Host a Greater Diversity of Planets

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    Probing the connection between a star's metallicity and the presence and properties of any associated planets offers an observational link between conditions during the epoch of planet formation and mature planetary systems. We explore this connection by analyzing the metallicities of Kepler target stars and the subset of stars found to host transiting planets. After correcting for survey incompleteness, we measure planet occurrence: the number of planets per 100 stars with a given metallicity MM. Planet occurrence correlates with metallicity for some, but not all, planet sizes and orbital periods. For warm super-Earths having P=10100P = 10-100 days and RP=1.01.7 RER_P = 1.0-1.7~R_E, planet occurrence is nearly constant over metallicities spanning -0.4 dex to +0.4 dex. We find 20 warm super-Earths per 100 stars, regardless of metallicity. In contrast, the occurrence of warm sub-Neptunes (RP=1.74.0 RER_P = 1.7-4.0~R_E) doubles over that same metallicity interval, from 20 to 40 planets per 100 stars. We model the distribution of planets as df10βMdMd f \propto 10^{\beta M} d M, where β\beta characterizes the strength of any metallicity correlation. This correlation steepens with decreasing orbital period and increasing planet size. For warm super-Earths β=0.30.2+0.2\beta = -0.3^{+0.2}_{-0.2}, while for hot Jupiters β=+3.40.8+0.9\beta = +3.4^{+0.9}_{-0.8}. High metallicities in protoplanetary disks may increase the mass of the largest rocky cores or the speed at which they are assembled, enhancing the production of planets larger than 1.7 RER_E. The association between high metallicity and short-period planets may reflect disk density profiles that facilitate the inward migration of solids or higher rates of planet-planet scattering.Comment: 32 pages, 15 figures, 9 tables, accepted for publication in The Astronomical Journa

    Decay of metastable phases in a model for the catalytic oxidation of CO

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    We study by kinetic Monte Carlo simulations the dynamic behavior of a Ziff-Gulari-Barshad model with CO desorption for the reaction CO + O \to CO2_2 on a catalytic surface. Finite-size scaling analysis of the fluctuations and the fourth-order order-parameter cumulant show that below a critical CO desorption rate, the model exhibits a nonequilibrium first-order phase transition between low and high CO coverage phases. We calculate several points on the coexistence curve. We also measure the metastable lifetimes associated with the transition from the low CO coverage phase to the high CO coverage phase, and {\it vice versa}. Our results indicate that the transition process follows a mechanism very similar to the decay of metastable phases associated with {\it equilibrium} first-order phase transitions and can be described by the classic Kolmogorov-Johnson-Mehl-Avrami theory of phase transformation by nucleation and growth. In the present case, the desorption parameter plays the role of temperature, and the distance to the coexistence curve plays the role of an external field or supersaturation. We identify two distinct regimes, depending on whether the system is far from or close to the coexistence curve, in which the statistical properties and the system-size dependence of the lifetimes are different, corresponding to multidroplet or single-droplet decay, respectively. The crossover between the two regimes approaches the coexistence curve logarithmically with system size, analogous to the behavior of the crossover between multidroplet and single-droplet metastable decay near an equilibrium first-order phase transition.Comment: 27 pages, 22 figures, accepted by Physical Review

    The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets

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    The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey (CKS) to study the size distribution of 2025 Kepler\textit{Kepler} planets in fine detail. We detect a factor of \geq2 deficit in the occurrence rate distribution at 1.5-2.0 R_{\oplus}. This gap splits the population of close-in (PP < 100 d) small planets into two size regimes: RP_P < 1.5 R_{\oplus} and RP_P = 2.0-3.0 R_{\oplus}, with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0 R_{\oplus} supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5 R_{\oplus} or smaller with varying amounts of low-density gas that determine their total sizes.Comment: Paper III in the California-Kepler Survey series, accepted to the Astronomical Journa

    The California-Kepler Survey. II. Precise Physical Properties of 2025 Kepler Planets and Their Host Stars

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    We present stellar and planetary properties for 1305 Kepler Objects of Interest (KOIs) hosting 2025 planet candidates observed as part of the California-Kepler Survey. We combine spectroscopic constraints, presented in Paper I, with stellar interior modeling to estimate stellar masses, radii, and ages. Stellar radii are typically constrained to 11%, compared to 40% when only photometric constraints are used. Stellar masses are constrained to 4%, and ages are constrained to 30%. We verify the integrity of the stellar parameters through comparisons with asteroseismic studies and Gaia parallaxes. We also recompute planetary radii for 2025 planet candidates. Because knowledge of planetary radii is often limited by uncertainties in stellar size, we improve the uncertainties in planet radii from typically 42% to 12%. We also leverage improved knowledge of stellar effective temperature to recompute incident stellar fluxes for the planets, now precise to 21%, compared to a factor of two when derived from photometry.Comment: 13 pages, 4 figures, 4 tables, accepted for publication in AJ; full versions of tables 3 and 4 are include

    The California-Kepler Survey. I. High Resolution Spectroscopy of 1305 Stars Hosting Kepler Transiting Planets

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    The California-Kepler Survey (CKS) is an observational program to improve our knowledge of the properties of stars found to host transiting planets by NASA's Kepler Mission. The improvement stems from new high-resolution optical spectra obtained using HIRES at the W. M. Keck Observatory. The CKS stellar sample comprises 1305 stars classified as Kepler Objects of Interest, hosting a total of 2075 transiting planets. The primary sample is magnitude-limited (Kp < 14.2) and contains 960 stars with 1385 planets. The sample was extended to include some fainter stars that host multiple planets, ultra short period planets, or habitable zone planets. The spectroscopic parameters were determined with two different codes, one based on template matching and the other on direct spectral synthesis using radiative transfer. We demonstrate a precision of 60 K in effective temperature, 0.10 dex in surface gravity, 0.04 dex in [Fe/H], and 1.0 km/s in projected rotational velocity. In this paper we describe the CKS project and present a uniform catalog of spectroscopic parameters. Subsequent papers in this series present catalogs of derived stellar properties such as mass, radius and age; revised planet properties; and statistical explorations of the ensemble. CKS is the largest survey to determine the properties of Kepler stars using a uniform set of high-resolution, high signal-to-noise ratio spectra. The HIRES spectra are available to the community for independent analyses.Comment: 20 pages, 19 figures, accepted for publication in AJ; a full version of Table 5 is included as tab_cks.csv and tab_cks.te

    An optical surface resonance may render photonic crystals ineffective

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    In this work we identify and study the presence of extremely intense surface resonances that frustrate the coupling of photons into a photonic crystal over crucial energy ranges. The practical utility of photonic crystals demands the capability to exchange photons with the external medium, therefore, it is essential to understand the cause of these surface resonances and a route to their elimination. We demonstrate that by modifying the surface geometry it is possible to tune the optical response or eliminate the resonances to enable full exploitation of the photonic crystal.Comment: 6 pages, 8 figures, submitted to PR

    Temporal inflection points in decorated pottery: a bayesian refinement of the late formative chronology in the Southern Lake Titicaca Basin, Bolivia

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    The Late Formative period immediately precedes the emergence of Tiwanaku, one of the earliest South American states, yet it is one of the most poorly understood periods in the southern Lake Titicaca Basin (Bolivia). In this article, we refine the ceramic chronology of this period with large sets of dates from eight sites, focusing on temporal inflection points in decorated ceramic styles. These points, estimated here by Bayesian models, index specific moments of change: (1) cal AD 120 (60-170, 95% probability): the first deposition of Kalasasaya red-rimmed and zonally incised styles; (2) cal AD 240 (190-340, 95% probability): a tentative estimate of the final deposition of Kalasasaya zonally incised vessels; (3) cal AD 420 (380-470, 95% probability): the final deposition of Kalasasaya red-rimmed vessels; and (4) cal AD 590 (500-660, 95% probability): the first deposition of Tiwanaku Redwares. These four modeled boundaries anchor an updated Late Formative chronology, which includes the Initial Late Formative phase, a newly identified decorative hiatus between the Middle and Late Formative periods. The models place Qeya and transitional vessels between inflection points 3 and 4 based on regionally consistent stratigraphic sequences. This more precise chronology will enable researchers to explore the trajectories of other contemporary shifts during this crucial period in Lake Titicaca Basin's prehistory.Fil: Marsh, Erik Johnson. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología Humana; ArgentinaFil: Roddick, Andrew P.. Mc Master University; CanadáFil: Bruno, Maria C.. Dickinson College; Estados UnidosFil: Smith, Scott C.. Franklin & Marshall College; Estados UnidosFil: Janusek, John W.. Vanderbilt University; Estados UnidosFil: Hastorf, Christine A.. University of California at Berkeley; Estados Unido
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