The Inquiry into \u3cem\u3eAitiai \u3c/em\u3ein Plato’s \u3cem\u3ePhaedo\u3c/em\u3e

Editor\u27s note: After blind peer review, this paper was selected for reading at the University of Dayton\u27s 10th annual Philosophy Colloquium, held Feb. 27-28, 1981. There is a feature of Socrates\u27 intellectual autobiography in the Phaedo that has not been sufficiently clarified by commentators on that passage. Most students of the dialogue have taken the text to describe Socrates\u27 disenchantment with mechanical reasons or explanations, his disappointment with Anaxagoras\u27 failure to provide sound teleological explanations, and his eventual turning to explanations involving the separated Forms. In very rough terms, to be sure, Socrates\u27 tale is thought to be about his switching allegiance from one type of reason or explanation to another. In reality, however, the import of Socrates\u27 autobiographical sketch is different from this. What Plato traces for us is not merely a set of changing convictions about specific reasons or explanations but rather an aborted attempt to come to know what it is to be an aitia or reason and an alternative method for arriving at a sufficiently strong belief about what an aitia is. Similar in purpose, then, to the familiar definitional projects of the early dialogues, Socrates\u27 inquiry into the nature of an aitia reaches an impasse. Unlike those stalled efforts, however, this one proceeds on an alternative course that results in a belief about what an aitia is. It is this belief, moreover, that constitutes the starting point for Socrates\u27 subsequent argument in behalf of the soul\u27s immortality

Trade-offs associated with dietary specialization in corallivorous butterflyfishes (Chaetodontidae: Chaetodon )

Author Posting. © Springer, 2007. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Behavioral Ecology and Sociobiology 62 (2008) 989-994, doi:10.1007/s00265-007-0526-8.Increasing dietary specialisation is an inherently risky strategy because it increases a species’ vulnerability to resource depletion. However, risks associated with dietary specialisation may be offset by increased performance when feeding on preferred prey. Though rarely demonstrated, highly specialised species are expected to outperform generalists when feeding on their preferred prey, whereas generalists are predicted to have more similar performance across a range of different prey. To test this theory, we compared growth rates of two obligate coral-feeding butterflyfishes (Chaetodon trifascialis and C. plebeius) maintained on exclusive diets of preferred versus non-preferred prey. In the field, C. trifascialis was the most specialised species, feeding almost exclusively on just one coral species, Acropora hyacinthus. Chaetodon plebeius meanwhile, was much less specialised, but fed predominantly on Pocillopora damicornis. During growth experiments, C. trifascialis grew fastest when feeding on A. hyacinthus and did not grow at all when feeding on less preferred prey (P. damicornis and Porites cylindrica). Chaetodon plebeius performed equally well on both A. hyacinthus and P. damicornis (its preferred prey), but performed poorly when feeding on P. cylindrica. Both butterflyfishes select coral species that maximise juvenile growth, but contrary to expectations, the more specialised species (C. trifascialis) did not outperform the generalist (C. plebeius) when both consumed their preferred prey. Increased dietary specialisation, therefore, appears to be a questionable strategy as there was no evidence of any increased benefits to offset increases in susceptibility to disturbance.This work was supported by a National Science Foundation (USA) Graduate Research Fellowship to ML

It’s Not Easy Going Green: Obstacles to Tree-Planting Programs in East Baltimore

In 2006, government officials in Baltimore announced plans to double the city’s tree canopy over the next thirty years. While the effort has already produced positive results, many parts of the city still lack trees. In this paper we consider whether two neighborhoods in East Baltimore – Berea and Madison-Eastend – are suitable locations for tree planting. We begin by calculating how much plantable space exists in each neighborhood. We then use interview data to cast light on how residents value the urban forest and whether or not they would support efforts to increase tree canopy in East Baltimore. The selection of East Baltimore as a study area is significant because it was here that the city’s Division of Forestry encountered resistance to tree planting in the 1960s. A secondary goal of our research is to determine whether a shift in the ethnic profile of this section of the city over the past fifty years has changed the way residents perceive and value the urban forest. Our results show that while there is enough plantable space in these two neighborhoods to increase tree canopy, from approximately six percent to over 16 percent, residents are not yet ready to fully embrace an aggressive tree planting program

The Gravitational Lens Candidate FBQ 1633+3134

We present our ground-based optical imaging, spectral analysis, and high resolution radio mapping of the gravitational lens candidate FBQ 1633+3134. This z=1.52, B=17.7 quasar appears double on CCD images with an image separation of 0.66 arcseconds and a flux ratio of ~3:1 across BVRI filters. A single 0.27 mJy radio source is detected at 8.46 GHz, coincident to within an arcsecond of both optical components, but no companion at radio wavelengths is detected down to a flux level of 0.1 mJy (3 sigma). Spectral observations reveal a rich metal-line absorption system consisting of a strong Mg II doublet and associated Fe I and Fe II absorption features, all at an intervening redshift of z=0.684, suggestive of a lensing galaxy. Point spread function subtraction however shows no obvious signs of a third object between the two quasar images, and places a detection limit of I > 23.0 if such an object exists. Although the possibility that FBQ 1633+3134 is a binary quasar cannot be ruled out, the evidence is consistent with it being a single quasar lensed by a faint, metal-rich galaxy.Comment: 24 pages, 5 figures. Accepted by AJ. A calibration error affecting B and V band apparent magnitudes has been corrected. The conclusions of the paper are not change

Simultaneous Estimation of Time Delays and Quasar Structure

We expand our Bayesian Monte Carlo method for analyzing the light curves of gravitationally lensed quasars to simultaneously estimate time delays and quasar structure including their mutual uncertainties. We apply the method to HE1104-1805 and QJ0158-4325, two doubly-imaged quasars with microlensing and intrinsic variability on comparable time scales. For HE1104-1805 the resulting time delay of (Delta t_AB) = t_A - t_B = 162.2 -5.9/+6.3 days and accretion disk size estimate of log(r_s/cm) = 15.7 -0.5/+0.4 at 0.2 micron in the rest frame are consistent with earlier estimates but suggest that existing methods for estimating time delays in the presence of microlensing underestimate the uncertainties. We are unable to measure a time delay for QJ0158-4325, but the accretion disk size is log(r_s/cm) = 14.9 +/- 0.3 at 0.3 micron in the rest frame.Comment: 21 pages, 6 figures, submitted to Ap

Anthropogenic land subsidence in the Perth Basin: Challenges for its retrospective geodetic detection

Recent-past subsidence of parts of the Perth Basin has most probably been caused by increased groundwater extraction for domestic and agricultural use. However, no dedicated geodetic monitoring programs were established when the increased extraction began in around 2000, thus setting a challenge to retrospectively quantify and map the subsidence. Differential levelling is likely to be less effective as only a few repeat traverses cover the areas thought to be subsiding. Repeat gravimetry is totally ineffective because of microseismic vibrations propagating through the Perth Basin. Repeat episodic GPS (Global Positioning System) is also likely to be less effective because of the few station occupations over several days or weeks and the inherent weakness of GPS for height determination. However, from a continuously operating GPS receiver at Gnangara and nearby artesian monitoring boreholes, we show that the rate of land subsidence has slowed from about -6 mm/yr to about -2 mm/yr since the reduction of groundwater extraction from the Yarragadee Aquifer in around 2005. A promising technique is InSAR (interferometric synthetic aperture radar) because it can map large areas, but the lack of historical radar imagery over the period of increased subsidence is a hindrance

Can health economics aid decision making in healthcare innovation in academia?

Health economics is extensively used by reimbursement agencies to make decisions on whether to adopt new medical technologies. It is also used by the healthcare industry as an aid to decision making during product development. This paper proposes that academic healthcare technology transfer could also benefit from adopting health economics. The study investigated the knowledge and attitudes of academic staff involved in developing and transferring healthcare technologies. The participants had little or no prior knowledge of health economics; however, the majority reported that this method had the potential to aid development and commercialisation. The innovations developed by the workshop attendees and their commercialisation plans were of a type that could potentially benefit from cost-effectiveness calculations. Health economics has the potential to make valuable contribution to academic healthcare innovation. Research is required to develop this method further and ensure that it can be successfully applied in academia

Addressing student models of energy loss in quantum tunnelling

We report on a multi-year, multi-institution study to investigate student reasoning about energy in the context of quantum tunnelling. We use ungraded surveys, graded examination questions, individual clinical interviews, and multiple-choice exams to build a picture of the types of responses that students typically give. We find that two descriptions of tunnelling through a square barrier are particularly common. Students often state that tunnelling particles lose energy while tunnelling. When sketching wave functions, students also show a shift in the axis of oscillation, as if the height of the axis of oscillation indicated the energy of the particle. We find inconsistencies between students' conceptual, mathematical, and graphical models of quantum tunnelling. As part of a curriculum in quantum physics, we have developed instructional materials to help students develop a more robust and less inconsistent picture of tunnelling, and present data suggesting that we have succeeded in doing so.Comment: Originally submitted to the European Journal of Physics on 2005 Feb 10. Pages: 14. References: 11. Figures: 9. Tables: 1. Resubmitted May 18 with revisions that include an appendix with the curriculum materials discussed in the paper (4 page small group UW-style tutorial