Radial Velocity Jitter in Stars from the California and Carnegie Planet Search at Keck Observatory

I present an empirical model for predicting a star's radial velocity jitter from its B-V color, activity level, and absolute magnitude. This model is based on observations of 450 well- observed stars from Keck Observatory for the California and Carnegie Planet Search Program. The model includes noise from both astrophysical sources and systematic errors, and describes jitter as generally increasing with a star's activity and height above the main sequence.Comment: 16 pages, 7 figures, PASP in pres

How companies without the benefit of authority create innovation through collaboration

To create new business firms develop and provide systems that are new to the market.\ud However, if a firm wants to achieve this goal but does not possess all required resources\ud and capabilities, it needs cooperation from other organizations. This study focuses\ud on how firms that lack authority to compel such cooperation, gain and foster\ud commitment from other organizations to cooperate. To develop a model that addresses\ud this question two cases of interorganizational innovation from the Dutch construction\ud industry were studied. In both cases an organization set up and coordinated a\ud network of organizations to jointly develop and market a new system. The cases suggest\ud that, in particular, three types of activities of such leading organizations affect\ud other organizations' commitment to cooperate. These include two types of activities\ud that correspond with two extensively researched constructs, champion behavior and\ud supportive leadership, and one type of activity whose influence is more indirect, value\ud proposition management. Overall, both cases can be regarded as examples of innovation\ud and value chain integration, two issues identified as industry deficiencies in various\ud countries

Control electronics for a neuro-electronic interface implemented in a gate array

Presents a Gate Array for implementing electronic circuitry to control multi-electrode arrays, which consist of 128 microelectrodes. The chip contains multiplexers, current sources and buffer amplifiers in CMOS technolog

A spiral structure in the disk of EX Draconis on the rise to outburst maximum

We report on the R-band eclipse mapping analysis of high-speed photometry of the dwarf nova EX Dra on the rise to the maximum of the November 1995 outburst. The eclipse map shows a one-armed spiral structure of ~180 degrees in azimuth, extending in radius from R ~0.2 to 0.43 R_{L1} (where R_{L1} is the distance from the disk center to the inner Lagrangian point), that contributes about 22 per cent of the total flux of the eclipse map. The spiral structure is stationary in a reference frame co-rotating with the binary and is stable for a timescale of at least 5 binary orbits. The comparison of the eclipse maps on the rise and in quiescence suggests that the outbursts of EX Dra may be driven by episodes of enhanced mass-transfer from the secondary star. Possible explanations for the nature of the spiral structure are discussed.Comment: To appear in the Astrophysical Journal Letters; 8 pages, 2 figures; coded with AAS latex styl

Dynamics of the solar chromosphere. V. High-frequency modulation in ultraviolet image sequences from TRACE

We search for signatures of high-frequency oscillations in the upper solar photosphere and low chromosphere in the context of acoustic heating of outer stellar atmospheres. We use ultraviolet image sequences of a quiet center-disk area from the Transition Region and Coronal Explorer (TRACE) mission which were taken with strict cadence regularity. The latter permits more reliable high-frequency diagnosis than in earlier work. Spatial Fourier power maps, spatially averaged coherence and phase-difference spectra, and spatio-temporal k-f decompositions all contain high-frequency features that at first sight seem of considerable intrinsic interest but actually are more likely to represent artifacts of different nature. Spatially averaged phase difference measurement provides the most sensitive diagnostic and indicates the presence of acoustic modulation up to f=20 mHz (periods down to 50 seconds) in internetwork areas.Comment: 9 pages, 8 figure

On the link between rotation, chromospheric activity and Li abundance in subgiant stars

The connection rotation-CaII emission flux-lithium abundance is analyzed for a sample of bona fide subgiant stars, with evolutionary status determined from HIPPARCOS trigonometric parallax measurements and from the Toulouse-Geneva code.Comment: 9 pages, 8 figure