Spanning, Valuation and Options

We model the space of marketed assets as a Riesz space of commodities. In this setting, two alternative characterizations are given of the space of continuous options on a bounded asset, s, with limited liability. The first characterization represents every continuous option on s as the uniform limit of portfolios of calls on s. The second characterization represents an option as a continuous sum (or integral) of Arrow-Debreu securities, with respect to s. The pricing implications of these representations are explored. In particular, the Breeden-Litzenberger pricing formula is shown to be a direct consequence of the integral representation theorem

Amblyrhiza and the Vertebrate Paleontology of Anguillean Caves

Recorded interest in the caves of Anguilla dates back to the second half of the nineteenth century. The earliest explorations were concerned with the locating phosphatic cave earths, and resulted in the mining of several sites. Incidental to this work, the bones of the largest island rodent ever discovered were collected from Aguillan caves. Whereas the phosphate mining operations were short-lived, the remains of the giant rodent Amblyrhiza have catalyzed a continued interest in the caves of Anguilla. The most recent series of explorations have provided the first adequate documentation of Amhlyrhiza fossil sites, and have started to yield radiometric dates

Spanning, Valuation and Options

We model the space of marketed assets as a Riesz space of commodities. In this setting, two alternative characterizations are given of the space of continuous options on a bounded asset, s, with limited liability. The first characterization represents every continuous option on s as the uniform limit of portfolios of calls on s. The second characterization represents an option as a continuous sum (or integral) of Arrow-Debreu securities, with respect to s. The pricing implications of these representations are explored. In particular, the Breeden-Litzenberger pricing formula is shown to be a direct consequence of the integral representation theorem.Securities, portfolios, assets, arbitrage, marketed assets

Body Size in Amblyrhiza inundata (Rodentia, Caviomorpha), an Extinct Megafaunal Rodent From the Anguilla Bank, West Indies: Estimates and Implications

Rodent species typically evolve larger mean body sizes when isolated on islands, but the extinct caviomorph Amblyrhiza inundata, known only from Quaternary cave deposits on the islands of Anguilla and St. Martin (northern Lesser Antilles), provides an unusually dramatic example of insular gigantism. Here we report on a series of body mass estimates for Amblyrhiza using predictive equations based on anteroposterior diameters and cortical cross-sectional areas of humeral and femoral diaphyses. Analyses of 14 isolated specimens (5 femoral, 9 humeral), all representing adult or near adult animals, yield body mass estimates ranging from slightly less than 50 kg to more than 200 kg. Body size estimates derived from humeral measurements are lower than those derived from femoral measurements, but the significance of this will remain unclear until matched limb bones (i.e., specimens from the same animal) are recovered. Incisor measurements are also highly variable, but in this case the distribution is demonstrably bimodal. Presence of multiple coeval species, temporal variation, limb heterogeneity, and sexual dimorphism all qualify as possible explanations of the variation encountered in Amblyrhiza data sets, but available samples are not adequate for making a robust choice among them. Body size affects many life history variables, including demography. Population estimates derived from empirical data and predictive equations suggest that only a few thousand individuals of Amblyrhiza could have occupied the islands of the Anguilla Bank at any one time during the Late Quaternary. At certain times-for example, during the last interglacial (Sangamonian) highstand-population numbers might have sunk to only a few hundred. Absolutely small population sizes of Amblyrhiza and severe fluctuations in island area during the late Quaternary surely affected its susceptibility to extinction, whether or not humans were ultimately responsible for the event (for which there is as yet no direct evidence)

Letters to the Editor

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65933/1/j.1528-1157.1995.tb00479.x.pd

Near Infrared Spectra and Intrinsic Luminosities of Candidate Type II Quasars at 2 < z < 3.4

We present JHK near-infrared (NIR) spectroscopy of 25 candidate Type II quasars selected from the Sloan Digital Sky Survey, using Triplespec on the Apache Point Observatory 3.5m telescope, FIRE at the Magellan/Baade 6.5m telescope, and GNIRS on Gemini. At redshifts of 2 < z < 3.4, our NIR spectra probe the rest-frame optical region of these targets, which were initially selected to have strong lines of CIV and Ly alpha, with FWHM<2000 km/s from the SDSS pipeline. We use the [OIII]5007 line shape as a model for the narrow line region emission, and find that \halpha\ consistently requires a broad component with FWHMs ranging from 1000 to 7500 km/s. Interestingly, the CIV lines also require broad bases, but with considerably narrower widths of 1000 to 4500 km/s. Estimating the extinction using the Balmer decrement and also the relationship in lower-z quasars between rest equivalent width and luminosity in the [OIII] line, we find typical A_V values of 0-2 mag, which naturally explain the attenuated CIV lines relative to Halpha. We propose that our targets are moderately obscured quasars. We also describe one unusual object with three distinct velocity peaks in its [OIII] spectrum.Comment: Accepted for publication in ApJ, 18 pages, 14 figure

Microbiome diversity and composition varies across body areas in a freshwater turtle

There is increasing recognition that microbiomes are important for host health and ecology, and understanding host microbiomes is important for planning appropriate conservation strategies. However, microbiome data are lacking for many taxa, including turtles. To further our understanding of the interactions between aquatic microbiomes and their hosts, we used next generation sequencing technology to examine the microbiomes of the Krefft's river turtle (Emydura macquarii krefftii). We examined the microbiomes of the buccal (oral) cavity, skin on the head, parts of the shell with macroalgae and parts of the shell without macroalgae. Bacteria in the phyla Proteobacteria and Bacteroidetes were the most common in most samples (particularly buccal samples), but Cyanobacteria, Deinococcus-thermus and Chloroflexi were also common (particularly in external microbiomes). We found significant differences in community composition among each body area, as well as significant differences among individuals. The buccal cavity had lower bacterial richness and evenness than any of the external microbiomes, and it had many amplicon sequence variants (ASVs) with a low relative abundance compared to other body areas. Nevertheless, the buccal cavity also had the most unique ASVs. Parts of the shell with and without algae also had different microbiomes, with particularly obvious differences in the relative abundances of the families Methylomonaceae, Saprospiraceae and Nostocaceae. This study provides novel, baseline information about the external microbiomes of turtles and is a first step in understanding their ecological roles

Hypoalbuminemia reflects nutritional risk, body composition and systemic inflammation and is independently associated with survival in patients with colorectal cancer

It has long been recognized that albumin has prognostic value in patients with cancer. However, although the Global Leadership Initiative on Malnutrition GLIM criteria (based on five diagnostic criteria, three phenotypic criteria and two etiologic criteria) recognize inflammation as an important etiologic factor in malnutrition, there are limited data regarding the association between albumin, nutritional risk, body composition and systemic inflammation, and whether albumin is associated with mortality independent of these parameters. The aim of this study was to examine the relationship between albumin, nutritional risk, body composition, systemic inflammation, and outcomes in patients with colorectal cancer (CRC). A retrospective cohort study (n = 795) was carried out in which patients were divided into normal and hypoalbuminaemic groups (albumin  &lt;35 g/L) in the presence and absence of a systemic inflammatory response C-reactive protein (CRP &gt;10 and &lt;10 mg/L, respectively). Post-operative complications, severity of complications and mortality were considered as outcome measures. Categorical variables were analyzed using Chi-square test χ 2or linear-by-linear association. Survival data were analyzed using univariate and multivariate Cox regression. In the presence of a systemic inflammatory response, hypoalbuminemia was directly associated with Malnutrition Universal Screening Tool MUST (p &lt; 0.001) and inversely associated with Body Mass Index BMI (p &lt; 0.001), subcutaneous adiposity (p &lt; 0.01), visceral obesity (p &lt; 0.01), skeletal muscle index (p &lt; 0.001) and skeletal muscle density (p &lt; 0.001). There was no significant association between hypoalbuminemia and either the presence of complications or their severity. In the absence of a systemic inflammatory response (n = 589), hypoalbuminemia was directly associated with MUST (p &lt; 0.05) and inversely associated with BMI (p &lt; 0.01), subcutaneous adiposity (p &lt; 0.05), visceral adiposity (p &lt; 0.05), skeletal muscle index (p &lt; 0.01) and skeletal muscle density (p &lt; 0.001). Hypoalbuminemia was, independently of inflammatory markers, associated with poorer cancer-specific and overall survival (both p &lt; 0.001). The results suggest that hypoalbuminemia in patients with CRC reflects both increased nutritional risk and greater systemic inflammatory response and was independently associated with poorer survival in patients with CRC

An upper limit to the dry merger rate at <z> ~ 0.55

We measure the fraction of Luminous Red Galaxies (LRGs) in dynamically close pairs (with projected separation less than 20 $h^{-1}$ kpc and velocity difference less than 500 km s$^{-1}$) to estimate the dry merger rate for galaxies with $-23 < M(r)_{k+e,z=0.2} +5 \log h < -21.5$ and $0.45 < z < 0.65$ in the 2dF-SDSS LRG and QSO (2SLAQ) redshift survey. For galaxies with a luminosity ratio of $1:4$ or greater we determine a $5\sigma$ upper limit to the merger fraction of 1.0% and a merger rate of $< 0.8 \times 10^{-5}$ Mpc$^{-3}$ Gyr$^{-1}$ (assuming that all pairs merge on the shortest possible timescale set by dynamical friction). This is significantly smaller than predicted by theoretical models and suggests that major dry mergers do not contribute to the formation of the red sequence at $z < 0.7$.Comment: 8 pages emulateapj style, 3 figures, accepted by AJ (March 2010