Howard Robertson to Mr. Jim Silver, 20 November 1963

Personal correspondenc

To The Fierce Guard in the Assyrian Saloon

The delight of this book is the constant surprise. Lee Douglas’s physical and contemplative world is where the quotidian meets the sublime and does a hula dance. Howard W. Robertson creates a persona who whispers in our ear to come along on his bumpy and glorious ride. The reader is then placed in lush rooms of wordplay and acute observation, while also being allowed a sense of intimacy. The poetry accesses Lee Douglas’s perspective with a curious and compelling simultaneity, akin to reading a journal and hearing internal monologue. This is a landscape where a sensei wears a cowboy hat and scrambled eggs are symptomatic of authentic being. However this is not an entirely ethereal world; the poems also create a narrative where we meet Douglas’s children, ex-wife, and even the new city budget manager. Robertson reminds the reader that living is a beautiful and terrible mystery that is best faced with humor, endurance, and love. Robertson’s intense language makes Lee Douglas’ perceptions a pleasurable and powerful reminder

The impact of d-amphetamine on resistance to extinction (RTE) in a single schedule preparation

Some researchers have suggested that the discrepancy in findings between studies of resistance-to-extinction that use single-schedules and those that use multiple-schedules is the result of increased discriminability between training and extinction conditions in the single-schedule preparation, masking the true relation between reinforcer density and resistance to extinction. Because d-amphetamine has been shown to interfere with stimulus control in a number of preparations, the current study examined the effects of d-amphetamine on rats’ lever-pressing in the context of a single-schedule resistance-to-extinction preparation. During training, doses of d-amphetamine or vehicle were administered 15 min prior to sessions in which the delivery of reinforcers occurred according to variable-interval 10-s, 90-s, or 240-s schedules. A 2-hr extinction session followed the 50-min training sessions, which occurred 5-7 days per week for each rat for at least 15 sessions. Pre-session injections of d-amphetamine resulted in higher resistance to extinction across all training schedules than pre-session injections of vehicle did, but d-amphetamine did not change the direction of the relation between reinforcer density and resistance to extinction. I discuss the results in a context that emphasizes the commonalities between resistance to extinction procedures completed in discrete trials and free-operant contexts with the hope of bridging the gap between these two bodies of literature

Next Generation Advanced Video Guidance Sensor Development and Test

The Advanced Video Guidance Sensor (AVGS) was the primary docking sensor for the Orbital Express mission. The sensor performed extremely well during the mission, and the technology has been proven on orbit in other flights too. Parts obsolescence issues prevented the construction of more AVGS units, so the next generation of sensor was designed with current parts and updated to support future programs. The Next Generation Advanced Video Guidance Sensor (NGAVGS) has been tested as a breadboard, two different brassboard units, and a prototype. The testing revealed further improvements that could be made and demonstrated capability beyond that ever demonstrated by the sensor on orbit. This paper presents some of the sensor history, parts obsolescence issues, radiation concerns, and software improvements to the NGAVGS. In addition, some of the testing and test results are presented. The NGAVGS has shown that it will meet the general requirements for any space proximity operations or docking need

Sequence Skill Acquisition and Off-Line Learning in Normal Aging

It is well known that certain cognitive abilities decline with age. The ability to form certain new declarative memories, particularly memories for facts and events, has been widely shown to decline with advancing age. In contrast, the effects of aging on the ability to form new procedural memories such as skills are less well known, though it appears that older adults are able to acquire some new procedural skills over practice. The current study examines the effects of normal aging on procedural memory more closely by comparing the effects of aging on the encoding or acquisition stage of procedural learning versus its effects on the consolidation, or between-session stage of procedural learning. Twelve older and 14 young participants completed a sequence-learning task (the Serial Reaction Time Task) over a practice session and at a re-test session 24 hours later. Older participants actually demonstrated more sequence skill during acquisition than the young. However, older participants failed to show skill improvement at re-test as the young participants did. Age thus appears to have a differential effect upon procedural learning stages such that older adults' skill acquisition remains relatively intact, in some cases even superior, compared to that of young adults, while their skill consolidation may be poorer than that of young adults. Although the effect of normal aging on procedural consolidation remains unclear, aging may actually enhance skill acquisition on some procedural tasks

An Empirically Derived Three-Dimensional Laplace Resonance in the Gliese 876 Planetary System

We report constraints on the three-dimensional orbital architecture for all four planets known to orbit the nearby M dwarf Gliese 876 based solely on Doppler measurements and demanding long-term orbital stability. Our dataset incorporates publicly available radial velocities taken with the ELODIE and CORALIE spectrographs, HARPS, and Keck HIRES as well as previously unpublished HIRES velocities. We first quantitatively assess the validity of the planets thought to orbit GJ 876 by computing the Bayes factors for a variety of different coplanar models using an importance sampling algorithm. We find that a four-planet model is preferred over a three-planet model. Next, we apply a Newtonian MCMC algorithm to perform a Bayesian analysis of the planet masses and orbits using an n-body model in three-dimensional space. Based on the radial velocities alone, we find that a 99% credible interval provides upper limits on the mutual inclinations for the three resonant planets ($\Phi_{cb}<6.20^\circ$ for the "c" and "b" pair and $\Phi_{be}<28.5^\circ$ for the "b" and "e" pair). Subsequent dynamical integrations of our posterior sample find that the GJ 876 planets must be roughly coplanar ($\Phi_{cb}<2.60^\circ$ and $\Phi_{be}<7.87^\circ$), suggesting the amount of planet-planet scattering in the system has been low. We investigate the distribution of the respective resonant arguments of each planet pair and find that at least one argument for each planet pair and the Laplace argument librate. The libration amplitudes in our three-dimensional orbital model supports the idea of the outer-three planets having undergone significant past disk migration.Comment: 19 pages, 11 figures, 8 tables. Accepted to MNRAS. Posterior samples available at https://github.com/benelson/GJ87

Gene regulatory network subcircuit controlling a dynamic spatial pattern of signaling in the sea urchin embryo

We dissect the transcriptional regulatory relationships coordinating the dynamic expression patterns of two signaling genes, wnt8 and delta, which are central to specification of the sea urchin embryo endomesoderm. cis-Regulatory analysis shows that transcription of the gene encoding the Notch ligand Delta is activated by the widely expressed Runx transcription factor, but spatially restricted by HesC-mediated repression through a site in the delta 5′UTR. Spatial transcription of the hesC gene, however, is controlled by Blimp1 repression. Blimp1 thus represses the repressor of delta, thereby permitting its transcription. The blimp1 gene is itself linked into a feedback circuit that includes the wnt8 signaling ligand gene, and we showed earlier that this circuit generates an expanding torus of blimp1 and wnt8 expression. The finding that delta expression is also controlled at the cis-regulatory level by the blimp1-wnt8 torus-generating subcircuit now explains the progression of Notch signaling from the mesoderm to the endoderm of the developing embryo. Thus the specific cis-regulatory linkages of the gene regulatory network encode the coordinated spatial expression of Wnt and Notch signaling as they sweep outward across the vegetal plate of the embryo