Agency

"There is agency in all we do: thinking, doing, or making. We invent a tune, play, or use it to celebrate an occasion. Or we make a conceptual leap and ask more abstract questions about the conditions for agency. They include autonomy and self-appraisal, each contested by arguments immersing us in circumstances we don’t control. But can it be true we that have no personal responsibility for all we think and do? Agency: Moral Identity and Free Will proposes that deliberation, choice, and free will emerged within the evolutionary history of animals with a physical advantage: organisms having cell walls or exoskeletons had an internal space within which to protect themselves from external threats or encounters. This defense was both structural and active: such organisms could ignore intrusions or inhibit risky behavior. Their capacities evolved with time: inhibition became the power to deliberate and choose the manner of one’s responses. Hence the ability of humans and some other animals to determine their reactions to problematic situations or to information that alters values and choices. This is free will as a material power, not as the conclusion to a conceptual argument. Having it makes us morally responsible for much we do. It prefigures moral identity. Closely argued but plainly written, Agency: Moral Identity and Free Will speaks for autonomy and responsibility when both are eclipsed by ideas that embed us in history or tradition. Our sense of moral choice and freedom is accurate. We are not altogether the creatures of our circumstances.

The comet rendezvous asteroid flyby mission

The Comet Rendezvous Asteroid Flyby (CRAF) mission is designed to answer the many questions raised by the Halley missions by exploring a cometary nucleus in detail, following it around its orbit and studying its changing activity as it moves closer to and then away from the Sun. In addition, on its way to rendezvous with the comet, CRAF will fly by a large, primitive class main belt asteroid and will return valuable data for comparison with the comet results. The selected asteroid is 449 Hamburga with a diameter of 88 km and a surface composition of carbonaceous chondrite meteorites. The expected flyby date is January, 1998. The CRAF spacecraft will continue to make measurements in orbit around the cometary nucleus as they both move closer to the Sun, until the dust and gas hazard becomes unsafe. At that point the spacecraft will move in and out between 50 and 2,500 kilometers to study the inner coma and the cometary ionosphere, and to collect dust and gas samples for onboard analysis. Following perihelion, the spacecraft will make a 50,000 km excursion down the comet's tail, further investigating the solar wind interaction with the cometary atmosphere. The spacecraft will return to the vicinity of the nucleus about four months after perihelion to observe the changes that have taken place. If the spacecraft remains healthy and adequate fuel is still onboard, an extended mission to follow the comet nucleus out to aphelion is anticipated

Agency

"There is agency in all we do: thinking, doing, or making. We invent a tune, play, or use it to celebrate an occasion. Or we make a conceptual leap and ask more abstract questions about the conditions for agency. They include autonomy and self-appraisal, each contested by arguments immersing us in circumstances we don’t control. But can it be true we that have no personal responsibility for all we think and do? Agency: Moral Identity and Free Will proposes that deliberation, choice, and free will emerged within the evolutionary history of animals with a physical advantage: organisms having cell walls or exoskeletons had an internal space within which to protect themselves from external threats or encounters. This defense was both structural and active: such organisms could ignore intrusions or inhibit risky behavior. Their capacities evolved with time: inhibition became the power to deliberate and choose the manner of one’s responses. Hence the ability of humans and some other animals to determine their reactions to problematic situations or to information that alters values and choices. This is free will as a material power, not as the conclusion to a conceptual argument. Having it makes us morally responsible for much we do. It prefigures moral identity. Closely argued but plainly written, Agency: Moral Identity and Free Will speaks for autonomy and responsibility when both are eclipsed by ideas that embed us in history or tradition. Our sense of moral choice and freedom is accurate. We are not altogether the creatures of our circumstances.

Thermal Shadows and Compositional Structure in Comet Nuclei

We use a fully 3-dimensional thermal evolution model to examine the effects of a non-uniform surface albedo on the subsurface thermal structure of comets. Surface albedo markings cast "thermal shadows", with strong lateral thermal gradients. Corresponding compositional gradients can be strong, especially if the crystallization of amorphous water ice is triggered in the hottest regions. We show that the spatial extent of the structure depends mainly on the obliquity, ther- mal conductivity and heliocentric distance. In some circumstances, subsurface structure caused by the thermal shadows of surface features can be maintained for more than 10 Myr, the median transport time from the Kuiper Belt to the inner solar system. Non-uniform compositional structure can be an evolutionary product and does not necessarily imply that comets consist of building blocks accumulated in different regions of the protoplanetary disk.Comment: Accepted in Ap

Cloning of terminal transferase cDNA by antibody screening

A cDNA library was prepared from a terminal deoxynucleotidyltransferase-containing thymoma in the phage vector λgt11. By screening plaques with anti-terminal transferase antibody, positive clones were identified of which some had β-galactosidase-cDNA fusion proteins identifiable after electrophoretic fractionation by immunoblotting with anti-terminal transferase antibody. The predominant class of cross-hybridizing clones was determined to represent cDNA for terminal transferase by showing that one representative clone hybridized to a 2200-nucleotide mRNA in close-matched enzyme-positive but not to enzyme-negative cells and that the cDNA selected a mRNA that translated to give a protein of the size and antigenic characteristics of terminal transferase. Only a small amount of genomic DNA hybridized to the longest available clone, indicating that the sequence is virtually unique in the mouse genome

The Increasing Rotation Period of Comet 10P/Tempel 2

We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band lightcurves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the data yields a double-peaked lightcurve and indicates a nucleus rotational period of 8.941 +/- 0.002 hr with a peak-to-peak amplitude of ~0.75 mag. Our data are sufficient to rule out all other possible double-peaked solutions as well as the single- and triple- peaked solutions. This rotation period agrees with one of five possible solutions found in post-perihelion data from 1994 by Mueller and Ferrin (1996, Icarus, 123, 463-477), and unambiguously eliminates their remaining four solutions. We applied our same techniques to published lightcurves from 1988 which were obtained at an equivalent orbital position and viewing geometry as in 1999. We found a rotation period of 8.932 +/- 0.001 hr in 1988, consistent with the findings of previous authors and incompatible with our 1999 solution. This reveals that Tempel 2 spun-down by ~32 s between 1988 and 1999 (two intervening perihelion passages). If the spin-down is due to a systematic torque, then the rotation period prior to perihelion during the 2010 apparition is expected to be an additional 32 s longer than in 1999.Comment: Accepted by The Astronomical Journal; 22 pages of text, 3 tables, 6 figure