Technology prospects and the cross-section of stock returns

In an economy with time-varying investment opportunities, the changes in technology prospects affect aggregate consumption and individual firm's future dividends, and lead to systematic technology risk. We construct a technology factor to track the changes in technology prospects measured by U.S. patent shocks, and find that this factor explains the growth of aggregate consumption, helps to price important stock portfolios, and carries significant risk premium. Our empirical results suggest the existence of technology risk in the cross-section of stock returns. © 2009 Elsevier B.V. All rights reserved.preprin

Early re-brightenings in GRB afterglows as signatures of low-to-high density boundary

The association of long gamma-ray bursts (GRBs) with star forming regions and the idea of massive stars as progenitors of GRBs are widely accepted. Because of their short lifetimes, it is very likely that massive stars are still embedded in dense molecular clouds when they give birth to GRBs. Stellar winds from GRB progenitors can create low-density bubbles with sizes and densities strongly depending on the initial ambient density. A boundary between the bubble and the dense molecular cloud must exist with the density at the boundary increasing from that of the bubble to that of the outer cloud. We have calculated the lightcurves of the afterglows in such environments with three regions: the stellar wind region, the boundary, and the molecular cloud. We show that the interaction between the cylindrical jet and the density boundary can result in a re-brightening of the afterglow occurring as early as ∼1 day after the GRB. We compare our models with the optical afterglows of GRB 970508, GRB 000301C, and GRB 030226. We find that the values of our model parameters, including the radius of the wind bubble, the densities in the bubble and in the outer molecular cloud are within typical ranges. © 2005 Elsevier B.V. All rights reserved.postprin

The role of the nature of the noise in the thermal conductance of mechanical systems

Focussing on a paradigmatic small system consisting of two coupled damped oscillators, we survey the role of the L\'evy-It\^o nature of the noise in the thermal conductance. For white noises, we prove that the L\'evy-It\^o composition (Lebesgue measure) of the noise is irrelevant for the thermal conductance of a non-equilibrium linearly coupled chain, which signals the independence between mechanical and thermodynamical properties. On the other hand, for the non-linearly coupled case, the two types of properties mix and the explicit definition of the noise plays a central role.Comment: 9 pages, 2 figures. To be published in Physical Review

Managed Bumblebees Outperform Honeybees in Increasing Peach Fruit Set in China: Different Limiting Processes with Different Pollinators

© 2015 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/4.0/ The file attached is the published version of the article

Performance of Equal Phase-Shift Search for One Iteration

Grover presented the phase-shift search by replacing the selective inversions by selective phase shifts of $\pi /3$. In this paper, we investigate the phase-shift search with general equal phase shifts. We show that for small uncertainties, the failure probability of the Phase-$\pi /3$ search is smaller than the general phase-shift search and for large uncertainties, the success probability of the large phase-shift search is larger than the Phase-$\pi /3$ search. Therefore, the large phase-shift search is suitable for large-size of databases.Comment: 10 pages, 4 figure

On a Subposet of the Tamari Lattice

We explore some of the properties of a subposet of the Tamari lattice introduced by Pallo, which we call the comb poset. We show that three binary functions that are not well-behaved in the Tamari lattice are remarkably well-behaved within an interval of the comb poset: rotation distance, meets and joins, and the common parse words function for a pair of trees. We relate this poset to a partial order on the symmetric group studied by Edelman.Comment: 21 page

Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees

email Suzanne orcd idCopyright: © 2015 Williams et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Extreme Food-Plant Specialisation in Megabombus Bumblebees as a Product of Long Tongues Combined with Short Nesting Seasons

© 2015 Huang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/4.0/ The attached file is the published version of the article

Diamagnetism of quantum gases with singular potentials

We consider a gas of quasi-free quantum particles confined to a finite box, subjected to singular magnetic and electric fields. We prove in great generality that the finite volume grand-canonical pressure is jointly analytic in the chemical potential ant the intensity of the external magnetic field. We also discuss the thermodynamic limit