Next-to-leading order predictions for WW+jet production

In this work we report on a next-to-leading order calculation of WW + jet production at hadron colliders, with subsequent leptonic decays of the W-bosons included. The calculation of the one-loop contributions is performed using generalized unitarity methods in order to derive analytic expressions for the relevant amplitudes. These amplitudes have been implemented in the parton-level Monte Carlo generator MCFM, which we use to provide a complete next-to-leading order calculation. Predictions for total cross-sections, as well as differential distributions for several key observables, are computed both for the LHC operating at 14 TeV as well as for a possible future 100 TeV proton-proton collider.Comment: 14 pages, 7 figures; v2: several references added, 2 typos corrected. Corresponds to published journal versio

Investigation of structural behavior of candidate Space Station structure

Quantitative evaluations of the structural loads, stiffness and deflections of an example Space Station truss due to a variety of influences, including manufacturing tolerances, assembly operations, and operational loading are reported. The example truss is a dual-keel design composed of 5-meter-cube modules. The truss is 21 modules high and 9 modules wide, with a transverse beam 15 modules long. One problem of concern is the amount of mismatch which will be expected when the truss is being erected on orbit. Worst-case thermal loading results in less than 0.5 inch of mismatch. The stiffness of the interface is shown to be less than 100 pounds per inch. Thus, only moderate loads will be required to overcome the mismatch. The problem of manufacturing imperfections is analyzed by the Monte Carlo approach. Deformations and internal loads are obtained for ensembles of 100 example trusses. All analyses are performed on a personal computer. The necessary routines required to supplement commercially available programs are described

Homogeneous CO Hydrogenation: Ligand Effects on the Lewis Acid-Assisted Reductive Coupling of Carbon Monoxide

Structure-function studies on the role of pendent Lewis acids in the reductive coupling of CO are reported. Cationic rhenium carbonyl complexes containing zero, one, or two phosphinoborane ligands (Ph_2P(CH_2)_nB(C_8H_(14)), n=1-3) react with the nucleophilic hydride [HPt(dmpe)_2]^+ to reduce [M-CO]^+ to M-CHO; this step is relatively insensitive to the Lewis acid, as both pendent (internal) and external boranes of appropriate acid strength can be used. In contrast, whether a second hydride transfer and C-C bond forming steps occur depends strongly on the number of carbon atoms between P and B in the phosphinoborane ligands, as well as the number of pendent acids in the complex: shorter linker chain lengths favor such reductive coupling, whereas longer chains and external boranes are ineffective. A number of different species containing partially reduced CO groups, whose exact structures vary considerably with the nature and number of phosphinoborane ligands, have been crystallographically characterized. The reaction of [(Ph -2P(CH_2)_2B(C_8H_(14)))_2Re(CO)4]^+ with [HPt(dmpe)_2]^+ takes place via a “hydride shuttle” mechanism, in which hydride is transferred from Pt to a pendent borane and thence to CO, rather than by direct hydride attack at CO. Addition of a second hydride in C_6D_5Cl at -40 ºC affords an unusual anionic bis(carbene) complex, which converts to a C-C bonded product on warming. These results support a working model for Lewis acid-assisted reductive coupling of CO, in which B (pendent or external) shuttles hydride from Pt to coordinated CO, followed by formation of an intramolecular B-O bond, which facilitates reductive coupling

A De-biased Direct Question Approach to Measuring Consumers' Willingness to Pay

Knowledge of consumers' willingness to pay (WTP) is a prerequisite to profitable price-setting. To gauge consumers' WTP, practitioners often rely on a direct single question approach in which consumers are asked to explicitly state their WTP for a product. Despite its popularity among practitioners, this approach has been found to suffer from hypothetical bias. In this paper, we propose a rigorous method that improves the accuracy of the direct single question approach. Specifically, we systematically assess the hypothetical biases associated with the direct single question approach and explore ways to de-bias it. Our results show that by using the de-biasing procedures we propose, we can generate a de-biased direct single question approach that is accu-rate enough to be useful for managerial decision-making. We validate this approach with two studies in this paper.Comment: Market Research, Pricing, Demand Estimation, Direct Estimation, Single Question Approach, Choice Experiments, Willingness to Pay, Hypothetical Bia

Homogeneous CO Hydrogenation: Dihydrogen Activation Involves a Frustrated Lewis Pair Instead of a Platinum Complex

During a search for conditions appropriate for Pt-catalyzed CO reduction using dihydrogen directly, metal-free conditions were discovered instead. A bulky, strong phosphazene base forms a “frustrated” Lewis pair (FLP) with a trialkylborane in the secondary coordination sphere of a rhenium carbonyl. Treatment of the FLP with dihydrogen cleanly affords multiple hydride transfers and C−C bond formation

The Impact of Collusion on Price Behavior: Empirical Results from Two Recent Cases

We used extensions of traditional ARCH and GARCH models to examine the difference in the behavior of the first two moments of the price distribution during collusion and the absence of it using prices from two recently discovered conspiracies, citric acid and lysine. According to our results, the citric acid conspiracy increased prices by 9 cents per pound relative to pre-cartel and post-cartel periods. The lysine conspiracy managed to raise prices by 25 cents per pound. In addition, the variance of prices during the lysine conspiracy was lower than the variance of prices during pre-cartel and post-cartel periods as we expected. In contrast, the variance of prices during the citric acid conspiracy was higher relative to more competitive periods.Demand and Price Analysis,

Mark E Josephson: Clinical Investigator

Mark E Josephson entered the world of clinical cardiac electrophysiology (EP) almost at its inception (1972); with so much to learn and so many directions one could take, he dived into the field with unbridled enthusiasm and an uncommon - perhaps almost unique - aptitude for asking questions and finding ways to answer them. Few aspects of EP escaped his indelible influence. In this short paper, I will attempt to touch on some of the high points of his astounding career as a clinical investigator

Concepts and analysis for precision segmented reflector and feed support structures

Several issues surrounding the design of a large (20-meter diameter) Precision Segmented Reflector are investigated. The concerns include development of a reflector support truss geometry that will permit deployment into the required doubly-curved shape without significant member strains. For deployable and erectable reflector support trusses, the reduction of structural redundancy was analyzed to achieve reduced weight and complexity for the designs. The stiffness and accuracy of such reduced member trusses, however, were found to be affected to a degree that is unexpected. The Precision Segmented Reflector designs were developed with performance requirements that represent the Reflector application. A novel deployable sunshade concept was developed, and a detailed parametric study of various feed support structural concepts was performed. The results of the detailed study reveal what may be the most desirable feed support structure geometry for Precision Segmented Reflector/Large Deployable Reflector applications

Observing IMBH-IMBH Binary Coalescences via Gravitational Radiation

Recent numerical simulations have suggested the possibility of forming double intermediate mass black holes (IMBHs) via the collisional runaway scenario in young dense star clusters. The two IMBHs formed would exchange into a common binary shortly after their birth, and quickly inspiral and merge. Since space-borne gravitational wave (GW) observatories such as LISA will be able to see the late phases of their inspiral out to several Gpc, and LIGO will be able to see the merger and ringdown out to similar distances, they represent potentially significant GW sources. In this Letter we estimate the rate at which LISA and LIGO will see their inspiral and merger in young star clusters, and discuss the information that can be extracted from the observations. We find that LISA will likely see tens of IMBH--IMBH inspirals per year, while advanced LIGO could see ~10 merger and ringdown events per year, with both rates strongly dependent on the distribution of cluster masses and densities.Comment: Accepted for publication in ApJL. Minor changes to reflect accepted version. 4 pages in emulateapj, 3 figure