Biology can use trained animals

The use of trained animals to solve complicated biological problems related to psychology is discussed. Data cover sensory and motor capacity. Several examples and experiments are described

Gas infall towards Sgr A* from the clumpy circumnuclear disk

We present the first large-scale mosaic performed with the Submillimeter Array (SMA) in the Galactic center. We have produced a 25-pointing mosaic, covering a ~2' x 2' area around Sgr A*. We have detected emission from two high-density molecular tracers, HCN(4-3) and CS(7-6), the latter never before reported in this region. The data have an angular resolution of 4.6" x 3.1", and the spectral window coverage is from -180 km/s to 1490 km/s for HCN(4-3) and from -1605 km/s to 129 km/s for CS(7-6). Both molecular tracers present a very clumpy distribution along the circumnuclear disk (CND), and are detected with a high signal-to-noise ratio in the southern part of the CND, while they are weaker towards the northern part. Assuming that the clumps are as close to the Galactic center as their projected distances, they are still dense enough to be gravitationally stable against the tidal shear produced by the supermassive black hole. Therefore, the CND is a non-transient structure. This geometrical distribution of both tracers suggests that the southern part of the CND is denser than the northern part. Also, by comparing the HCN(4-3) results with HCN(1-0) results we can see that the northern and the southern parts of the CND have different excitation levels, with the southern part warmer than the northern. Finally, we compare our results with those obtained with the detection of NH3, which traces the warmer and less dense material detected in the inner cavity of the CND. We suggest that we are detecting the origin point where a portion of the CND becomes destabilized and approaches the dynamical center of the Milky Way, possibly being impacted by the southern streamer and heated on its way inwards.Comment: 35 pages, 25 figures, 2 tables, accepted for publication in ApJ, emulate-apj styl

A 4% Geometric Distance to the Galaxy NGC4258 from Orbital Motions in a Nuclear Gas Disk

The water maser in the mildly active nucleus in the nearby galaxy NGC4258 traces a thin, nearly edge-on, subparsec-scale Keplerian disk. Using the technique of very long baseline interferometry, we have detected the proper motions of these masers as they sweep in front of the central black hole at an orbital velocity of about 1100 km/s. The average maser proper motion of 31.5 microarcseconds per year is used in conjunction with the observed acceleration of the masers to derive a purely geometric distance to the galaxy of 7.2 +- 0.3 Mpc. This is the most precise extragalactic distance measured to date, and, being independent of all other distance indicators, is likely to play an important role in calibrating the extragalactic distance scale.Comment: 11 pages, 3 figures. Accepted for publication in Natur

Active rendezvous between a low-earth orbit user spacecraft and the Space Transportation System (STS) shuttle

Active rendezvous of an unmanned spacecraft with the Space Transportation System (STS) Shuttle is considered. The various operational constraints facing both the maneuvering spacecraft and the Shuttle during such a rendezvous sequence are discussed. Specifically, the actively rendezvousing user spacecraft must arrive in the generic Shuttle control box at a specified time after Shuttle launch. In so doing it must at no point violate Shuttle separation requirements. In addition, the spacecraft must be able to initiate the transfer sequence from any point in its orbit. The four-burn rendezvous sequence incorporating two Hohmann transfers and an intermediate phasing orbit as a low-energy solution satisfying the above requirements are discussed. The general characteristics of the four-burn sequence are discussed, with emphasis placed on phase orbit altitude and delta-velocity requirements. The planning and execution of such a sequence in the operational environment are then considered. Factor crucial in maintaining the safety of both spacecraft, such as spacecraft separation and contingency analysis, are considered in detail

Doctor of Philosophy

dissertationBusiness ethics theory tends to focus on major ethical issues in business, and while this understandable, it is incomplete. This paper argues that minor ethical matters in business are also important and should not be ignored. Furthermore, a virtue ethics critique is an instructive approach to showing why minor ethical matters are important in business and how ethics theory gives insights into how to properly handle minor ethical matters in the business domain. Through analysis of case studies, psychological experiments, and philosophy thought experiments, I show in four chapters how a virtue ethics critique gives an illuminating analysis of minor ethical matters in the business domain. The first chapter uses ideas found in the Mencius about how importance and praiseworthiness relate to major and minor ethical matters. The next three chapters look at two virtues and one vice -honesty, hypocrisy, and candidness-and how these character traits play out in the business domain concerning minor ethical matters. The chapter on honesty captures the praiseworthiness of being honest in business relationships in minor ethical matters. The chapter on hypocrisy examines the claim that in minor ethical matters, hypocrisy in business could be a virtue; in reply, I argue that integrity in minor ethical matters is virtuous, but in certain kinds of business situations, proper pretense, which can look like hypocrisy, should be employed. The chapter on candidness (how much private information agents should reveal about themselves) argues that virtuous agents in business are cautious against full disclosure in minor ethical matters, particularly in social networking media. From analyzing honesty, hypocrisy, and candidness in the business domain, I conclude that a virtue ethics critique gives an enlightening analysis for the following reasons: (1) for agents in business, thinking in virtuous terms helps them to see that minor ethical matters should be thought of in ethical terms, (2) thinking in terms of character reveals how we want agents in business to act in minor ethical matters, and (3) dealing with issues from a character standpoint potentially improves the agent's dealing with minor ethical matters in business