Possible misinterpretation of lunar cratering record in Voyager team analyses of outer planet satellites

While interpreting outer planetary satellites, the Voyager imaging team repeatedly referred to a lunar frontside highland calibration curve. It was assumed that it is unmodified and not in steady state equilibrium, but rather records all impacts that have occurred. It was also assumed that it records the size distribution of an early population of impactors, called Population I, evidence for which was found on various satellites. New evidence is reported that the Voyager team interpretation of this population is wrong, a conclusion that seriously affects the cratering histories reported for outer planet satellites

Studies of relationships among outer solar system small bodies and related objects

This program involves telescopic observations of colorimetry, spectroscopy, and photometry of small bodies of the solar system, emphasizing possible relationships among outer solar system asteroids, comets, and certain satellites. Earth approacher targets of opportunity and lab spectroscopic studies are included

Comments on comet shapes and aggregation processes

An important question for a comet mission is whether comet nuclei preserve information clarifying aggregation processes of planetary matter. New observational evidence shows that Trojan asteroids, as a group, display a higher fraction of highly-elongated objects than the belt. More recently evidence has accumulated that comet nuclei, as a group, also display highly-elongated shapes at macro-scale. This evidence comes from the several comets whose nuclear lightcurves or shapes have been well studied. Trojans and comet nuclei share other properties. Both groups have extremely low albedos and reddish-to neutral-black colors typical of asteroids of spectral class D, P, and C. Both groups may have had relatively low collision frequencies. An important problem to resolve with spacecraft imaging is whether these elongated shapes are primordial, or due to evolution of the objects. Two hypotheses that might be tested by a combination of global-scale and close-up imaging from various directions are: (1) The irregular shapes are primordial and related to the fact that these bodies have had lower collision frequencies than belt asteroids; or (2) The irregular shapes may be due to volatile loss

Ideas of Culture in an Urban American Indian Behavioral Health Clinic.

The culture concept maintains an extended history of being taken up by diverse groups and ascribed different meanings to serve distinct agendas. This is certainly true of the ideas of culture circulating at the intersections of American Indian (AI) and behavioral health (BH) settings where popular culture concepts have been problematized by modern culture theorists yet continue to inform clinical practice. An afterthought in most BH settings, culture and its role in supporting the wellness of AI peoples is of primary concern for Indian Health Service sponsored BH clinics. As a result, I partnered with one such clinic in a Midwestern urban AI health organization to better understand the relations between culture concepts and clinical practice by conducting a clinic ethnography. Findings highlight a major disjunction between how service providers (SPs) talked about culture and clinical practice in abstract (cultural re-connection) and how they described and demonstrated clinical practice in concrete (cultural re-imagination). This disjunction reflects a major predicament facing the fields of BH wherein engagement with traditional cultures stands at odds with modern American cultural assumptions embedded in clinical training. Encouraged to engage with traditional AI cultural forms, SPs in this clinic—like their counterparts across fields of BH—did not abandon their modern clinical training. Instead, by adding symbols of cultural difference to otherwise standard, high quality clinical practice, they repackaged clinically familiar ideas, tools, and techniques as culturally different. Rather than immersion into a life-world familiar to AI ancestors ala cultural re-connection, then, SPs engaged clients in cultural re-imagination by using representations of AI culture in therapy to assist in fashioning positive modern Native identities to buttress against messages of devaluation encountered in modern America. While likely a therapeutic re-imagining of AI culture for distressed clients, concerns were raised around essentialism in representations of Indigeneity and socio-political processes of re-imagining AI peoples as populations demarcated by a circumscribed expressions of identity difference legible within contemporary BH. Finally, this work underscores the essential role of cultural analyses via ethnography for any rigorous science of clinical practice.PhDPsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/133390/1/williaha_1.pd

The influence of agitation on a continuous counter-current liquid-liquid extraction column

This work presents operating data and correlations of agitated extraction equipment studied under continuous counter-current flow. The experimental work was carried out in at agitated column 36 inches in length with an internal diameter of 2 inches using the system toluene, benzoic acid and water. The working section of the column was 24 inches. The design of the column used for the experimental work is similar to that proposed in a patent by van Dijck (3). The column is similar only to the extent that the patent covers numerous conditions of vertical agitation. The distribution data and the equilibrium solubility curve were determined by Appel and Elgin (1). The experimental results obtained indicate that an agitated counter-current extraction column possesses a number of advantages over its stationary counterpart. Agitation increases the efficiency of a liquid liquid extraction column and by proper control of agitation the extraction coefficient can be made nearly independent of the dispersed phase flow rate. The results obtained also made possible the derivation of an empirical equation correlating H.T.U., agitation and thruput for the system benzoic acid, toluene and water. (H.T.U.)= 33.4/T (2.73 - Log10 R.P.M.

Reverse Carleson Embeddings for Model Spaces

The classical embedding theorem of Carleson deals with finite positive Borel measures $\mu$ on the closed unit disk for which there exists a positive constant $c$ such that $|f|_{L^2(\mu)} \leq c |f|_{H^2}$ for all $f \in H^2$, the Hardy space of the unit disk. Lef\'evre et al. examined measures $\mu$ for which there exists a positive constant $c$ such that $\|f\|_{L^2(\mu)} \geq c |f|_{H^2}$ for all $f \in H^2$. The first type of inequality above was explored with $H^2$ replaced by one of the model spaces $(\Theta H^2)^{\perp}$ by Aleksandrov, Baranov, Cohn, Treil, and Volberg. In this paper we discuss the second type of inequality in $(\Theta H^2)^{\perp}$.Comment: 33 page

Experimental studies of collision and fragmentation phenomena

The reduction and publication of an extensive data set collected in experiments over several years at Ames and PSI is briefly examined. Hartmann has been assembling data sets from his experiments on catastrophic fragmentation of various materials, including basalt, other igneous rock, ice, and weak dirt clods. Weidenschilling and Davis have continued to gather and reduce data on oblique impacts. The data indicate a power law distribution of ejecta mass vs. velocity, with a slope that is independent of azimuth, and does not vary with impact angle from normal impacts to at least 75 deg from vertical. In order to improve models of coagulation of dust aggregates in the solar nebula, SJW developed an apparatus for drop tests of fragile projectiles. Davis and Weidenschilling continued to collect and analyze experimental data on collisional catastrophic disruption at the Ames Vertical Gun Range

Frequency dependence of the interaural time difference thresholds in human listeners

[EN] Interaural time difference (ITD) thresholds for sine tones were measured as a function of frequency with unprecedented resolution along the frequency axis. The tone level was 70 dB SPL, and the method was a two¿interval forced¿choice, three¿down one¿up staircase. Overall, the lowest thresholds occurred near 1000 Hz. At lower frequencies, thresholds varied more rapidly than the expected 1/f law, suggesting a growing deficit in elemental ITD processors as characteristic frequency decreases. At higher frequencies, thresholds increased dramatically with increasing frequency. Measurements at 50¿Hz increments were able to obtain a threshold for only one listener at 1500 Hz, but no threshold at 1550 Hz. In summary, performance varied from best to impossible over a range of about half an octave. In that sense, ITD thresholds appear to show the most dramatic frequency dependence of any auditory quantity.Dunai ., L.; Hartmann, W. (2011). Frequency dependence of the interaural time difference thresholds in human listeners. The Journal of the Acoustical Society of America. 129(4):2485-2485. doi:10.1121/1.3588183S24852485129

Comparative planetology of early intense cratering and other cratering effects

Intense early cratering in the first few hundred million years of the solar system, its decline to the present rate, and the consequent effects on the evolution of planetary surfaces were studied

Studies of early intense cratering and possible saturation effects

Crater counts on Rhea were completed, to be compared and combined with independent counts by Steve Squyres; the material is now being integrated into a study of cratering on Rhea and other Saturn satellites by Squyres, Lissauer, and Hartmann. Special attention is being paid to lighting and other effects on the apparent changes in crater density from one region to another. An earlier proposal by the author on crater density was further tested. Brief preliminary results are given