Distinguishing compact binary population synthesis models using gravitational-wave observations of coalescing binary black holes

The coalescence of compact binaries containing neutron stars or black holes is one of the most promising signals for advanced ground-based laser interferometer gravitational-wave detectors, with the first direct detections expected over the next few years. The rate of binary coalescences and the distribution of component masses is highly uncertain, and population synthesis models predict a wide range of plausible values. Poorly constrained parameters in population synthesis models correspond to poorly understood astrophysics at various stages in the evolution of massive binary stars, the progenitors of binary neutron star and binary black hole systems. These include effects such as supernova kick velocities, parameters governing the energetics of common envelope evolution and the strength of stellar winds. Observing multiple binary black hole systems through gravitational waves will allow us to infer details of the astrophysical mechanisms that lead to their formation. Here we simulate gravitational-wave observations from a series of population synthesis models including the effects of known selection biases, measurement errors and cosmology. We compare the predictions arising from different models and show that we will be able to distinguish between them with observations (or the lack of them) from the early runs of the advanced LIGO and Virgo detectors. This will allow us to narrow down the large parameter space for binary evolution models.Comment: 16 pages, 8 figures, updated to match version published in Ap

Optimal composition of hybrid/blended real estate portfolios

Purpose: The purpose of this paper is to establish an optimum mix of liquid, publicly traded assets that may be added to a real estate portfolio, such as those held by open-ended funds, to provide the liquidity required by institutional investors such as UK defined contribution pension funds. This is with the objective of securing liquidity while not unduly compromising the risk-return characteristics of the underlying asset class. This paper considers the best mix of liquid assets at different thresholds for a liquid asset allocation, with the performance then evaluated against that of a direct real estate benchmark index. Design/Methodology/Approach: The authors employ a mean-tracking error optimisation approach in determining the optimal combination of liquid assets that can be added to a real estate fund portfolio. The returns of the optimised portfolios are compared to the returns for portfolios that employ the use of either cash or listed real estate alone as a liquidity buffer. Multivariate Generalised Autoregressive models are used along with rolling correlations and tracking errors to gauge the effectiveness of the various portfolios in tracking the performance of the benchmark index. Findings: The results indicate that applying formal optimisation techniques leads to a considerable improvement in the ability of the returns from blended real estate portfolios to track the underlying real estate market. This is the case at a number of different thresholds for the liquid asset allocation and in cases where a minimum return requirement is imposed. Practical Implications: The results suggest that real estate fund managers can realise the liquidity benefits of incorporating publicly traded assets into their portfolios without sacrificing the ability to deliver real estate-like returns. However, in order to do so, a wider range of liquid assets must be considered, not just cash. Originality/value: Despite their importance in the real estate investment industry, comparatively few studies have examined the structure and operation of open-ended real estate funds. To the authors’ knowledge, this is the first study to analyse the optimal composition of liquid assets within blended or hybrid real estate portfolios

Enclosing the Whole: Woolf’s “Kew Gardens” as Autopoetic Narrative

En proposant une lecture autopoiétique de “Kew Gardens”, nouvelle publiée en 1919, cet article se fonde sur une interprétation de l'empirisme et de l'expérimentation dans les premières nouvelles de Woolf plus littérale que celle généralement adoptée par les critiques. L'autopoiesis est ici définie simplement comme le processus selon lequel un système reproduit l'organisation qui le définit comme système dans le cadre de son environnement élargi. De telles lectures ont été appliquées à la science-fiction et à la fiction cyberpunk ainsi qu'à la fiction d'auteurs tels que Pynchon et DeLillo, dont le thème suggère déjà ce type d'interprétation. Cependant, à ma connaissance, aucune lecture autopoiétique n'a été faite d'un écrivain “traditionnel” comme Woolf—dont le thème dans “Kew Gardens” n'est pas explicitement autopoiétique—ni de la forme narrative en général qui prenne en compte sa création d'un espace physique, temporel et linguistique fermé. La réflexivité du système—ici, narratif—nécessite la présence de l'observateur extérieur—ici l'auteur/lecteur—à l'intérieur du système. Cependant, alors que l'auteur/lecteur insuffle vie au système depuis l'intérieur de ce système,  “Kew Gardens” met en avant l'impersonnalité mécanique du monde qu'il décrit, les ruptures dans l'espace verbal ou linguistique, les interstices ou le “bruit” entre les mots

Nesting Success of the Bluegill, Lepomis Macrochirus Rafinesque, in a Small Ohio Farm Pond

Author Institution: Academic Faculty of Population and Environmental Biology, The Ohio State University, Columbus, Ohio 43210Some of the factors influencing the reproductive success of the bluegill sunfish, Lepomis macrochirus Rafinesque, in an Ohio farm poind were investigated during three summers from 1965 to 1967. The availability of nesting substrate was the major variable affecting spawning success in the pond. Fine gravel and sand substrates produced the most fry. Those of mud and debris produced less fry. Chemical control of algal mats in 1965 and 1967, by providing open areas of preferred substrate, increased nesting success and thus indirectly contributed to overpopulation of bluegills in the pond

Rosmarinic acid in Canna generalis activates the medial deterrent chemosensory neurone and deters feeding in the tobacco hornworm Manduca sexta

For all but a very few highly specialized insect feeders, Canna generalis L. (Cannaceae) is unacceptable as a food plant and is a highly potent feeding deterrent for the tobacco hornworm Manduca sexta Johan. (Lepidoptera). The present study describes the isolation of an active deterrent compound, rosmarinic acid (RA) from the ethanol extract of canna leaves. A two‐choice bioassay shows that RA is a feeding deterrent in the concentration range 0.3–3 mm. Bilateral ablation of the oral chemoreceptors eliminates this deterrence. The results reported in the behavioural literature show that only the epipharyngeal sensilla and the medial (but not the lateral) styloconica contribute to this deterrence elicited by canna foliage or extract, and the data obtained in the present study show the same results using RA. Electrophysiological recordings from the medial styloconica show that RA primarily stimulates the ‘deterrent neurone’ in a concentration‐dependent manner with a threshold of approximately 0.03 mm and a peak frequency of 69 spikes s–1 at 0.1 mm RA. An extract of canna leaves elicits similar responses. Adding RA to canna extract does not elicit another class of spikes, indicating that both stimuli activate the same neurone. We discuss the significance of the results with respect to furthering our knowledge about the sensory basis of food selection, and specifically about the range of compounds that stimulate deterrent chemosensitive neurones of lepidopteran larvae

Biosynthesis of selenate reductase in <i>Salmonella enterica</i>:critical roles for the signal peptide and DmsD

Salmonella enterica serovar Typhimurium is a Gram-negative bacterium with a flexible respiratory capability. Under anaerobic conditions, S. enterica can utilize a range of terminal electron acceptors, including selenate, to sustain respiratory electron transport. The S. enterica selenate reductase is a membrane-bound enzyme encoded by the ynfEFGH-dmsD operon. The active enzyme is predicted to comprise at least three subunits where YnfE is a molybdenum-containing catalytic subunit. The YnfE protein is synthesized with an N-terminal twin-arginine signal peptide and biosynthesis of the enzyme is coordinated by a signal peptide binding chaperone called DmsD. In this work, the interaction between S. enterica DmsD and the YnfE signal peptide has been studied by chemical crosslinking. These experiments were complemented by genetic approaches, which identified the DmsD binding epitope within the YnfE signal peptide. YnfE signal peptide residues L24 and A28 were shown to be important for assembly of an active selenate reductase. Conversely, a random genetic screen identified the DmsD V16 residue as being important for signal peptide recognition and selenate reductase assembly