Price anomalies in the used car market.

[Dataset available: http://hdl.handle.net/10411/15566]

Field Theory reformulated without Self-energy Parts. The dressing Operator

The reformulation of field theory for avoiding self-energy parts in the dynamical evolution has been applied successfully in the framework of the Lee model, [M. de Haan. Ann. Phys., 311, 314-349 (2004)] enabling a kinetic extension of the description. The basic ingredient is the recognition of these self-energy parts. [M. de Haan and C. George. Trends in Statistical Physics 3 (2000), 115] The original reversible description is embedded in the new one and appears now as a restricted class of initial conditions. [M. de Haan and C. George. Prog. Theor. Phys.,109, 881-909 (2003)] This program is realized here in the reduced formalism for a scalar field, interacting with a two-level atom, beyond the usual rotating wave approximation. The kinetic evolution operator, previously surmised, [M. de Haan. Physica, A171 (1991), 159] is here derived from first principles, justifying the usual practice in optics where the common use of the so-called pole approximation should no longer be viewed as an approximation but as an alternative description in the appropriate formalism. That model illustrates how some dressing of the atomic levels (and vertices), through an appropriate operator, finds its place naturally into the new formalism since the bare and dressed ground states do no longer coincide. Moreover, finite velocity for field propagation is now possible in all cases, without the presence of precursors for multiple detections.Comment: 55 pages. Revised version for Annals of Physics. Typos and English corrections, references and precisions adde

Exact Markovian kinetic equation for a quantum Brownian oscillator

We derive an exact Markovian kinetic equation for an oscillator linearly coupled to a heat bath, describing quantum Brownian motion. Our work is based on the subdynamics formulation developed by Prigogine and collaborators. The space of distribution functions is decomposed into independent subspaces that remain invariant under Liouville dynamics. For integrable systems in Poincar\'e's sense the invariant subspaces follow the dynamics of uncoupled, renormalized particles. In contrast for non-integrable systems, the invariant subspaces follow a dynamics with broken-time symmetry, involving generalized functions. This result indicates that irreversibility and stochasticity are exact properties of dynamics in generalized function spaces. We comment on the relation between our Markovian kinetic equation and the Hu-Paz-Zhang equation.Comment: A few typos in the published version are correcte

Specialization of neural mechanisms underlying face recognition in human infants

Newborn infants respond preferentially to simple face-like patterns, raising the possibility that the face-specific region, identified in the adult cortex are functioning from birth. We sought to evaluate this hypothesis by characterizing the specificity Of infants' electrocortical responses to faces in two ways: (1) comparing responses to faces of humans with those to faces of nonhuman primates; and 2) comparing responses to upright and inverted faces. Adults' face-responsive N170 event-related potential (ERP) component showed specificity to upright human faces that was not observable at any point in the ERPs Of infants. A putative "infant N170" did show sensitivity to the species of the face, but the orientation of the face did not influence processing until a later stage. These findings suggest a process of gradual specialization of cortical face processing systems during postnatal development

Met moeite lage kostprijs in 2000

Dit artikel laat zien hoe de kostprijs in 2000 is opgebouwd. Het maakt een vergelijking met praktijkbedrijven

Sellers' hedging incentives at EPA's emission trading auction

Cason (1993)argued thattheauction theEPAused in order to start the market for sulfur allowances, is not efficient. The set-up of the auction gives both buyers and sellers an incentive to understate their valuation of an allowance. In this paper, we show that the sellers’ incentives are even more perverse than Cason suggested. In particular, we show that sellers have an incentive to set their ask price equal to zero, while simultaneously hedging their bets by submitting a positive bid. It is not possible to derive the Nash equilibrium for this set-up. If such an equilibrium exists, sellers either set only a positive ask price, or an ask price equal to zero, and a positive bid as well.

Giant magnetoresistance in Co/Cu multilayers sputtered with Kr

This paper presents some results of magnetoresistance measurements on Kr-sputter-deposited Co/Cu multilayers. We find that Co/Cu MLs sputtered with Kr gas show a larger GMR effect than those sputtered with Ar gas

Auctions with rent seeking

We present a model which combines elements of an auction and a rent-seeking contest. Players compete for a prize. Apart from exerting lobbying efforts, they also have to submit a bid which is payable only if they win the prize. First, we ana-lyze the model if the returns-to-scale parameters of both bids and efforts are unity. We present a necessary and sufficient condition for the existence of a unique Nash equilibrium. In the equilibrium each player submits the same bid, while the sum of all efforts equals that bid. Second, we analyze the case in which the returns-to-scale parameters may differ from unity, and derive the implications of that specification.

Visual pathways from the perspective of cost functions and multi-task deep neural networks

Vision research has been shaped by the seminal insight that we can understand the higher-tier visual cortex from the perspective of multiple functional pathways with different goals. In this paper, we try to give a computational account of the functional organization of this system by reasoning from the perspective of multi-task deep neural networks. Machine learning has shown that tasks become easier to solve when they are decomposed into subtasks with their own cost function. We hypothesize that the visual system optimizes multiple cost functions of unrelated tasks and this causes the emergence of a ventral pathway dedicated to vision for perception, and a dorsal pathway dedicated to vision for action. To evaluate the functional organization in multi-task deep neural networks, we propose a method that measures the contribution of a unit towards each task, applying it to two networks that have been trained on either two related or two unrelated tasks, using an identical stimulus set. Results show that the network trained on the unrelated tasks shows a decreasing degree of feature representation sharing towards higher-tier layers while the network trained on related tasks uniformly shows high degree of sharing. We conjecture that the method we propose can be used to analyze the anatomical and functional organization of the visual system and beyond. We predict that the degree to which tasks are related is a good descriptor of the degree to which they share downstream cortical-units.Comment: 16 pages, 5 figure