1,702 research outputs found
Indirect observation of unobservable interstellar molecules
It is suggested that the abundances of neutral non-polar interstellar molecules unobservable by radio astronomy can be systematically determined by radio observation of the protonated ions. As an example, observed N2H(+) column densities are analyzed to infer molecular nitrogen abundances in dense interstellar clouds. The chemistries and expected densities of the protonated ions of O2, C2, CO2, C2H2 and CH4 are then discussed. Microwave transition frequencies fo HCO2(+) and C2H3(+) are estimated, and a preliminary astronomical search for HCO2(+) is described
A Recombination-Based Tabu Search Algorithm for the Winner Determination Problem
Abstract. We propose a dedicated tabu search algorithm (TSX_WDP) for the winner determination problem (WDP) in combinatorial auctions. TSX_WDP integrates two complementary neighborhoods designed re-spectively for intensification and diversification. To escape deep local optima, TSX_WDP employs a backbone-based recombination opera-tor to generate new starting points for tabu search and to displace the search into unexplored promising regions. The recombination operator operates on elite solutions previously found which are recorded in an global archive. The performance of our algorithm is assessed on a set of 500 well-known WDP benchmark instances. Comparisons with five state of the art algorithms demonstrate the effectiveness of our approach
License prices for financially constrained firms
It is often alleged that high auction prices inhibit service deployment. We investigate this claim under the extreme case of financially constrained bidders. If demand is just slightly elastic, auctions maximize consumer surplus if consumer surplus is a convex function of quantity (a common assumption), or if consumer surplus is concave and the proportion of expenditure spent on deployment is greater than one over the elasticity of demand. The latter condition appears to be true for most of the large telecom auctions in the US and Europe. Thus, even if high auction prices inhibit service deployment, auctions appear to be optimal from the consumers’ point of view
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Multiphoton radiative recombination of electron assisted by laser field
In the presence of an intensive laser field the radiative recombination of
the continuum electron into an atomic bound state generally is accompanied by
absorption or emission of several laser quanta. The spectrum of emitted photons
represents an equidistant pattern with the spacing equal to the laser
frequency. The distribution of intensities in this spectrum is studied
employing the Keldysh-type approximation, i.e. neglecting interaction of the
impact electron with the atomic core in the initial continuum state. Within the
adiabatic approximation the scale of emitted photon frequencies is subdivided
into classically allowed and classically forbidden domains. The highest
intensities correspond to emission frequencies close to the edges of
classically allowed domain. The total cross section of electron recombination
summed over all emitted photon channels exhibits negligible dependence on the
laser field intensity.Comment: 14 pages, 5 figures (Figs.2-5 have "a" and "b" parts), Phys.Rev.A
accepted for publication. Fig.2b is presented correctl
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On the distribution of bids for construction contract auctions
The statistical distribution representing bid values constitutes an essential part of many auction models and has involved a wide range of assumptions, including the Uniform, Normal, Lognormal and Weibull densities. From a modelling point of view, its goodness is defined by how well it enables the probability of a particular bid value to be estimated – a past bid for ex-post analysis and a future bid for ex-ante (forecasting) analysis. However, there is no agreement to date of what is the most appropriate form and empirical work is sparse.
Twelve extant construction datasets from four continents over different time periods are analysed in this paper for their fit to a variety of candidate statistical distributions assuming homogeneity of bidders (ID not known). The results show there is no one single fit-all distribution, but that the 3p Log-Normal, Fréchet/2p Log-Normal, Normal, Gamma and Gumbel generally rank the best ex-post, and the 2p Log-Normal, Normal, Gamma and Gumbel the best ex-ante – with ex-ante having around three to four times worse fit than ex-post. Final comments focus on the results relating to the third and fourth standardised moments of the bids and a post-hoc rationalisation of the empirical outcome of the analysis
Three Wide-Separation L dwarf Companions from the Two Micron All Sky Survey: Gl 337C, Gl 618.1B, and HD 89744B
We present two confirmed wide separation L-dwarf common proper motion
companions to nearby stars and one candidate identified from the Two Micron All
Sky Survey. Spectral types from optical spectroscopy are L0 V, L2.5 V, and L8
V. Near-infrared low resolution spectra of the companions are provided as well
as a grid of known objects spanning M6 V -- T dwarfs to support spectral type
assignment for these and future L-dwarfs in the z'JHK bands. Using published
measurements, we estimate ages of the companions from physical properties of
the primaries. These crude ages allow us to estimate companion masses using
theoretical low-mass star and brown dwarf evolutionary models. The new L-dwarfs
in this paper bring the number of known wide-binary (Separation >= 100 AU)
L-dwarf companions of nearby stars to nine. One of the L-dwarfs is a wide
separation companion to the F7 IV-V + extrasolar planet system HD89744Ab.Comment: 20 pages including 6 tables and 4 figures, AJ, in pres
A New Auction for Substitutes: Central-Bank Liquidity Auctions, 'Toxic Asset' Auctions, and Variable Product-Mix Auctions
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Analysis of the distribution of the number of bidders in construction contract auctions
The number of bidders, N, involved in a construction procurement auction is known to have an important effect on the value of the lowest bid and the mark-up applied by bidders. In practice, for example, it is important for a bidder to have a good estimate of N when bidding for a current contract. One approach, instigated by Friedman in 1956, is to make such an estimate by statistical analysis and modelling. Since then, however, finding a suitable model for N has been an enduring problem for researchers and, despite intensive research activity in the subsequent 30 years, little progress has been made, due principally to the absence of new ideas and perspectives. The debate is resumed by checking old assumptions, providing new evidence relating to concomitant variables and proposing a new model. In doing this and in order to ensure universality, a novel approach is developed and tested by using a unique set of 12 construction tender databases from four continents. This shows the new model provides a significant advancement on previous versions. Several new research questions are also posed and other approaches identified for future study
Relationship Bonds and Customer Loyalty: A Study Across Different Service Contexts
The benefits of customer relationship strategies are well known and somewhat established nowadays. Customer loyalty emerges as the crucial glue in developing a relational approach. However, relational bonds, which relate to customer loyalty, have not yet been fully explored. Also, there is little research that takes into account the effect of service types on customer relationships and bonding. This paper develops a conceptual framework based on previous literature with a complete set of different relational bonds and examines its influence on customer loyalty across search, experience and credence services through a survey-based empirical study, with a sample of 233 consumers. The results provide guidance to managers to differentiate customer relationship strategies according to each specific service context
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