The Luminosity Function of the Hot and Cold Kuiper belt Populations

Abridged. We have performed an ecliptic survey of the Kuiper belt, with an areal coverage of 8.9 square degrees to a 50% limiting magnitude of r'=24.7, and have detected 88 Kuiper belt objects, roughly half of which received follow-up one to two months after detection. Using this survey data alone, we have measured the luminosity function of the Kuiper belt, thus avoiding any biases that might come from the inclusion of other observations. We have found that the Cold population defined as having inclinations less than 5 degrees has a luminosity function slope alpha=0.82+-0.23, and is different from the Hot population, which has inclinations greater than 5 degrees and a luminosity function slope alpha=0.35+-0.21. As well, we have found that those objects closer than 38 AU have virtually the same luminosity function slope as the Hot population. This result, along with similar findings of past surveys demonstrates that the dynamically cold Kuiper belt objects likely have a steep size distribution, and are unique from all of the excited populations which have much shallower distributions. This suggests that the dynamically excited population underwent a different accretion history and achieved a more evolved state of accretion than the cold population. As well, we discuss the similarities of the Cold and Hot populations with the size distributions of other planetesimal populations. We find that while the Jupiter family comets and the scattered disk exhibit similar size distributions, a power-law extrapolation to small sizes for the scattered disk cannot account for the observed influx of comets. As well, we have found that the Jupiter Trojan and Hot populations cannot have originated from the same parent popuation, a result that is difficult to reconcile with scattering models similar to the NICE model.Comment: Accepted for publication in Icarus. 27 pages, 10 figures, 4 table

The Small Numbers of Large Kuiper Belt Objects

We explore the brightness distribution of the largest and brightest (m(R) 5°) from the very brightest to m(R) = 23. We find for m(R) ≾ 23, a single slope appears to describe the luminosity function. We estimate that ~12 KBOs brighter than m(R) ~ 19.5 are present in the Kuiper Belt today. With nine bodies already discovered this suggests that the inventory of bright KBOs is nearly complete

INITIAL EVALUATION OF CYCLIC ADENOSINE MONOPHOSPHATE ENZYME IMMUNOASSAY FOR USE WITH CRANE SEMEN SAMPLES

The management of ex situ and in situ populations of many wildlife species requires detailed knowledge of a species’ reproductive biology. For species such as cranes, where artificial insemination is a critical component of ex situ management strategies, understanding normal sperm function is especially important. Previous research has shown that captive cranes exhibit highly variable production and quality of semen samples produced by individual males and high levels of variation of cell concentration and motility across different species. Cyclic adenosine monophosphate (cyclic AMP) has been implicated in regulating sperm function, such as cell motility, and may affect an individual’s ability to successfully fertilize. Here we demonstrate the feasibility of an enzyme-linked immunosorbent assay (ELISA) for measuring cyclic AMP produced by crane sperm to facilitate future research into its role in sperm function and fertilization

A Search for Distant Solar System Bodies in the Region of Sedna

We present the results of a wide-field survey for distant Sedna-like bodies in the outer solar system using the 1.2-m Samuel Oschin Telescope at Palomar Observatory. We searched ~12,000 square degrees down to a mean limiting magnitude of 21.3 in R. A total number of 53 Kuiper belt objects and Centaurs have been detected; 25 of which were discovered in this survey. No additional Sedna-like bodies with perihelia beyond 70 AU were found despite a sensitivity to motions out to ~1000 AU. We place constraints on the size and distribution of objects on Sedna orbits.Comment: 10 pages, 3 figures, accepted by ApJ Letter

HOW STRESSFUL IS IT TO MOVE? WHOOPING CRANE GLUCOCORTICOID RESPONSE DURING FACILITY TRANSFER

The ability to transfer animals between different facilities for genetic management is a critical component to the success of any cooperatively managed captive animal population despite the high cost and the need for a high level of coordination in logistical planning. Two issues of concern are the magnitude of potential stress responses incurred during shipment of adult cranes to a new facility and the duration of elevated glucocorticoid production during the acclimation periods. The objectives of this project were to assess adrenal responses of whooping cranes (Grus americana) during transfer from the Patuxent Wildlife Research Center (PWRC) to other facilities across North America and the influence of transit time on acclimation duration. We conducted 2 separate studies to assess patterns of glucocorticoid production. When comparing the 3 stages of transfer (study 1), fecal glucocorticoid metabolite (FGM) concentrations were significantly higher in samples collected from the crate compared to both before and after transfer. During the acclimation period at the new facilities (study 2), 2 patterns emerged, where some birds showed an immediate response then little change in FGM production while others displayed variable production throughout the sampling period. We believe that these different patterns may be due to differences in personality and is an avenue for future investigation. Results from this study help inform future management decisions for individuals being transferred and acclimation to new facilities

Freshwater Mussel Shells as Environmental Chronicles: Geochemical and Taphonomic Signatures of Mercury-Related Extirpations in the North Fork Holston River, Virginia

This study utilized freshwater mussel shells to assess mercury (Hg) contamination in the North Fork Holston River that extirpated (caused local extinctions of) a diverse mussel fauna. Shells (n = 366) were collected from five sites situated upstream (two sites), just below (one site), and downstream (two sites) of the town of Saltville, Virginia, where Hg was used to produce chlorine and caustic soda from 1950 to 1972. Shell samples were used to test the (1) utility of geochemical signatures of shells for assessing the spatial variation in Hg levels in the river relative to the contamination source and (2) value of taphonomy (post-mortem shell alteration) for distinguishing sites that differ in extirpation histories. Geochemical signatures of 40 shells, analyzed using atomic absorption spectroscopy, indicated a strong longitudinal pattern. All shells from the two upstream sites had low Hg concentrations (<5−31 μg/kg), shells directly below Saltville had variable, but dramatically higher concentrations (23−4637 μg/kg), and shells from the two downstream sites displayed intermediate Hg levels (<5−115 μg/kg) that declined with distance from Saltville. Two pre-industrial shells, collected at Saltville in 1917, yielded very low Hg estimates (5−6 μg/kg). Hg signatures were consistent among mussel species, suggesting that Hg concentrations were invariant to species type; most likely, highly variable Hg levels, both across sites and through time, overwhelmed any interspecific differences in Hg acquisition. Also, a notable post-mortem incorporation of Hg in mussel shells seemed unlikely, as the Hg content was not correlated with shell taphonomy (r = 0.18; p = 0.28). The taphonomic analysis (n = 366) showed that the degree of shell alteration reliably distinguished sites with different extirpation histories. At Saltville, where live mussels have been absent for at least 30 years, shells were most heavily altered and fragmented. Conversely, fresh-looking shells abounded upstream, where reproducing mussel populations are still present. In summary, relic shells offered valuable spatio-temporal data on Hg concentrations in a polluted ecosystem, and shell taphonomic signatures discriminated sites with different extirpation histories. The shell-based strategies exemplified here do not require sampling live specimens and may augment more standard strategies applied to environmental monitoring. The approach should prove especially useful in areas with unknown extirpation and pollution histories

Properties of the Distant Kuiper Belt: Results from the Palomar Distant Solar System Survey

We present the results of a wide-field survey using the 1.2-m Samuel Oschin Telescope at Palomar Observatory. This survey was designed to find the most distant members of the Kuiper belt and beyond. We searched ~12,000 deg2 down to a mean limiting magnitude of 21.3 in R. A total number of 52 KBOs and Centaurs have been detected, 25 of which were discovered in this survey. Except for the re-detection of Sedna, no additional Sedna-like bodies with perihelia greater than 45 AU were detected despite sensitivity out to distances of 1000 AU. We discuss the implications for a distant Sedna- like population beyond the Kuiper belt, focusing on the constraints we can place on the embedded stellar cluster environment the early Sun may be have been born in, where the location and distribution of Sedna-like orbits sculpted by multiple stellar encounters is indicative of the birth cluster size. We also report our observed latitude distribution and implications for the size of the plutino population.Comment: 40 pages, 12 figures, 3 tables Accepted by Ap