Second Best Efficiency in Auctions

We characterize the incentive compatible allocation that maximizes the expected social surplus in a single-unit sale when the efficient allocation is not implementable. This allocation may involve no selling when it is efficient to sell. We then show that the English auction always implements the second best allocation when there are only two bidders, but not with more than two. Our model employs a unidimensional type space with independent types and allocative externalities, but captures some features of models with multidimensional types.Efficiency, auctions, mechanism design

Comment on: Nonmonotonic dx2−y2d_{x^{2}-y^{2}} Superconducting Order Parameter in Nd2−x_{2-x}Cex_xCuO4_4

In a recent letter Blumberg and collaborators claim that a non-monotonic $d_{x^2-y^2}$ form for the superconducting order parameter is required to explain their Raman scattering measurements in Nd$_{2-x}$Ce$_x$CuO$_4$ . In this comment we show with a simple model calculation that the basis for this conclusion is insufficient. The proposed functional dependence of the gap is neither consistent with their measured spectra nor compatible with other experimental results. Therefore the issue of the superconduing gap in electron-doped systems cannot be considered solved by now.Comment: Comment to the paper by Blumberg et al., Phys. Rev. Lett., 88, 107002 (2002

Optical oxygen sensing with artificial intelligence

Luminescence-based sensors for measuring oxygen concentration are widely used in both industry and research due to the practical advantages and sensitivity of this type of sensing. The measuring principle is the luminescence quenching by oxygen molecules, which results in a change of the luminescence decay time and intensity. In the classical approach, this change is related to an oxygen concentration using the Stern-Volmer equation. This equation, which in most cases is non-linear, is parameterized through device-specific constants. Therefore, to determine these parameters, every sensor needs to be precisely calibrated at one or more known concentrations. This study explored an entirely new artificial intelligence approach and demonstrated the feasibility of oxygen sensing through machine learning. The specifically developed neural network learns very efficiently to relate the input quantities to the oxygen concentration. The results show a mean deviation of the predicted from the measured concentration of 0.5% air, comparable to many commercial and low-cost sensors. Since the network was trained using synthetically generated data, the accuracy of the model predictions is limited by the ability of the generated data to describe the measured data, opening up future possibilities for significant improvement by using a large number of experimental measurements for training. The approach described in this work demonstrates the applicability of artificial intelligence to sensing technology and paves the road for the next generation of sensors

Quantum Interference Phenomena Between Impurity States in d-wave Superconductors

We investigate the mutual influence of impurities in two-dimensional d-wave superconductors involving self-consistent solutions of the Bogoliubov-de Gennes equations. The local order parameter suppression, the local density of states (LDOS) as well as the interference of impurity-induced structures are analyzed. We employ an impurity position averaging scheme for the DOS that does not neglect these interference effects, as the commonly used $T$-matrix approaches do.Comment: 4 eps figures, presented at SNS200

D.H. Lawrence's Etruscan Seduction

Abstract: Sketches of Etruscan Places is especially important among D.\u2007H.\u2007Lawrence\u2019s later works not only because it is the work that completes the image of a restless, indefatigable traveler looking for a new gospel in old cultures and in faraway countries, but also because it offers stimulating and surprisingly modern reflections on the relationship between dominant and subordinate cultures. For centuries historians, archaeologists, linguists and scholars had tried to penetratethe mysteryof theEtruscans inorder toexplain their origin,interpret their symbols and read their language. Lawrence attempted to give his own interpretationof thatancient mysterious worldas heviewed theEtruscans asthe symbol of a lost vitality.\u2007His interpretation of this lost civilization insists on the \u201cmanipulation of cultural heritage,\u201d which anticipates ideas expressed by Ronald BarthesinMythologies(1957).Asaresult,Lawrenceunderminestraditionalviews of Etruscan civilization as vassal to Greek and Roman civilization and defends its individuality.\u2007Finally,Lawrenceanticipatespost-colonialideasbydeconstructing the centrality of the Western historical and cultural system of values and reconstructing, although partially, the non-canonical multiplicity of ethnic separateness

On the use of reserve prices in the English auction

We show that the introduction of a reserve price may promote entry, increase social welfare, and also induce higher revenues. The first two facts are in stark contrast with the relationship between reserve prices and entry pointed out by the literature. Our different result is obtained in a setting in which potential entrants arrive sequentially and face the risk of incurring losses conditional on winning the object on sale

Promoting Entry and Efficiency via Reserve Prices

Reserve prices are used by sellers to modify the allocation induced by standard auctions. The existing literature has shown that, if the number of bidders is fixed, a reserve price can be used to increase expected revenues. This comes at the expense of efficiency when the auctioned good goes unsold. Instead, when the number of bidders is not fixed, a reserve price may discourage entry. The reduction in the number of bidders caused by the reserve price in this situation is detrimental for both revenues and efficiency. This work shows that a different conclusion may emerge when potential entrants arrive sequentially and face the risk of incurring losses conditional on winning the object on sale. In fact, we show that reserve prices may lead to more entry and raise the efficiency. Applications characterized by the presence of an incumbent who is better informed about some common characteristics of the object for sale may yield the type of features that are needed for our different conclusion to hold