12,770 research outputs found
Complementarity + Back-reaction is enough
We investigate a recent development of the black hole information problem, in
which a practical paradox has been formulated to show that complementarity is
insufficient. A crucial ingredient in this practical paradox is to distill
information from the early Hawking radiation within the past lightcone of the
black hole. By causality this action can back-react on the black hole. Taking
this back-reaction into account, the paradox could be resolved without invoking
any new physics beyond complementarity. This resolution requires a certain
constraint on the S-matrix to be satisfied. Further insights into the S-matrix
could potentially be obtained by effective-field-theory computations of the
back-reaction on the nice slice.Comment: v2, 21 pages, 4 figure
Optimal pricing using online auction experiments: A P\'olya tree approach
We show how a retailer can estimate the optimal price of a new product using
observed transaction prices from online second-price auction experiments. For
this purpose we propose a Bayesian P\'olya tree approach which, given the
limited nature of the data, requires a specially tailored implementation.
Avoiding the need for a priori parametric assumptions, the P\'olya tree
approach allows for flexible inference of the valuation distribution, leading
to more robust estimation of optimal price than competing parametric
approaches. In collaboration with an online jewelry retailer, we illustrate how
our methodology can be combined with managerial prior knowledge to estimate the
profit maximizing price of a new jewelry product.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS503 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Dundee Discussion Papers in Economics 155:Lobbying for protection under uncertainty: a real option approach
Dundee Discussion Papers in Economics 155:Lobbying for protection under uncertainty: a real option approach
Virial expansion for a strongly correlated Fermi gas with imbalanced spin populations
Quantum virial expansion provides an ideal tool to investigate the
high-temperature properties of a strongly correlated Fermi gas. Here, we
construct the virial expansion in the presence of spin population imbalance. Up
to the third order, we calculate the high-temperature free energy of a unitary
Fermi gas as a function of spin imbalance, with infinitely large, attractive or
repulsive interactions. In the latter repulsive case, we show that there is no
itinerant ferromagnetism when quantum virial expansion is applicable. We
therefore estimate an upper bound for the ferromagnetic transition temperature
. For a harmonically trapped Fermi gas at unitarity, we find that
, where is the Fermi temperature at the center
of the trap. Our result for the high-temperature equations of state may
confront future high-precision thermodynamic measurements.Comment: 7 pages, 5 figures, accepted in Phys. Rev.
Controlling for heterogeneity in gravity models of trade and integration
This paper compares various specifications of the gravity model of trade as nested versions of a general specification that uses bilateral country-pair fixed effects to control for heterogeneity. For each specification, we show that the atheoretical restrictions used to obtain them from the general model are not supported statistically. Because the gravity model has become the "workhorse" baseline model for estimating the effects of international integration, this has important empirical implications. In particular, we show that, unless heterogeneity is accounted for correctly, gravity models can greatly overestimate the effects of integration on the volume of trade.International trade
Controlling for heterogeneity in gravity models of trade and integration
This paper compares various specifications of the gravity model of trade as nested versions of a general specification that uses bilateral country-pair fixed effects to control for heterogeneity. For each specification, we show that the a theoretical restrictions to obtain them from the general model are not supported statistically. Because the gravity model has become the ‘workhorse’ baseline model for estimating the effects of international integration, this has important empirical implications. In particular, we show that, unless heterogeneity is accounted for correctly, gravity models can greatly overestimate the effects of integration on the volume of trade.International trade
Galpha 12 and Galpha 13 Are Phosphorylated during Platelet Activation
The ubiquitously expressed G-proteins G12 and G13 whose function is currently not clear have been shown to be activated in platelet membranes through receptors that stimulate platelet aggregation. We used intact human platelets to determine whether alpha subunits of both G-proteins can be phosphorylated under physiological conditions. Activation of human platelets by thrombin and the thromboxane A2 receptor agonist U46619 lead to phosphorylation of Galpha 12 and Galpha 13. Phosphorylation occurred rapidly after addition of thrombin and was not mediated by glycoprotein IIb/IIIa (integrin alpha IIbbeta 3) activation. Phosphorylation of Galpha 12 and Galpha 13 could be mimicked by phorbol 12-myristate 13-acetate, and thrombin-induced phosphorylation was inhibited by the protein kinase C inhibitor calphostin C indicating an involvement of protein kinase C in Galpha 12/13 phosphorylation induced by thrombin in human platelets. The phosphorylation of both G protein alpha subunits was reconstituted in COS-7 cells cotransfected with Galpha 12 or Galpha 13 and different protein kinase C isoforms. Among the protein knase C isoforms tested, protein kinase C beta , delta , and epsilon were most effective in promoting phosphorylation of Galpha 12 and Galpha 13 in a phorbol 12-myristate 13-acetate-dependent manner. These data demonstrate that Galpha 12 and Galpha 13 are phosphorylated under in vivo conditions and that this phosphorylation involves protein kinase C
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