Higher Algebraic Structures and Quantization

We derive (quasi-)quantum groups in 2+1 dimensional topological field theory directly from the classical action and the path integral. Detailed computations are carried out for the Chern-Simons theory with finite gauge group. The principles behind our computations are presumably more general. We extend the classical action in a d+1 dimensional topological theory to manifolds of dimension less than d+1. We then ``construct'' a generalized path integral which in d+1 dimensions reduces to the standard one and in d dimensions reproduces the quantum Hilbert space. In a 2+1 dimensional topological theory the path integral over the circle is the category of representations of a quasi-quantum group. In this paper we only consider finite theories, in which the generalized path integral reduces to a finite sum. New ideas are needed to extend beyond the finite theories treated here.Comment: 62 pages + 16 figures (revised version). In this revision we make some small corrections and clarification

On the Role of Pre-Determined Rules for HRM Policies

Using simple game-theoretical models, this paper studies the role of pre-determined rules for HRM policies. We consider a model in which HRM decisions affect employees' self-images and thereby their motivation. We show that in the absence of written rules, managers are too reluctant (1) to differentiate between employees on the basis of their abilities, and (2) to terminate employment of employees on probation. Generally, organizations benefit from committing to strict rules for various HRM practices

Entanglement between Demand and Supply in Markets with Bandwagon Goods

Whenever customers' choices (e.g. to buy or not a given good) depend on others choices (cases coined 'positive externalities' or 'bandwagon effect' in the economic literature), the demand may be multiply valued: for a same posted price, there is either a small number of buyers, or a large one -- in which case one says that the customers coordinate. This leads to a dilemma for the seller: should he sell at a high price, targeting a small number of buyers, or at low price targeting a large number of buyers? In this paper we show that the interaction between demand and supply is even more complex than expected, leading to what we call the curse of coordination: the pricing strategy for the seller which aimed at maximizing his profit corresponds to posting a price which, not only assumes that the customers will coordinate, but also lies very near the critical price value at which such high demand no more exists. This is obtained by the detailed mathematical analysis of a particular model formally related to the Random Field Ising Model and to a model introduced in social sciences by T C Schelling in the 70's.Comment: Updated version, accepted for publication, Journal of Statistical Physics, online Dec 201

THERMAL CONDUCTIVITY FOR A NOISY DISORDERED HARMONIC CHAIN

We consider a $d$-dimensional disordered harmonic chain (DHC) perturbed by an energy conservative noise. We obtain uniform in the volume upper and lower bounds for the thermal conductivity defined through the Green-Kubo formula. These bounds indicate a positive finite conductivity. We prove also that the infinite volume homogenized Green-Kubo formula converges

Heat Conduction and Entropy Production in Anharmonic Crystals with Self-Consistent Stochastic Reservoirs

We investigate a class of anharmonic crystals in $d$ dimensions, $d\ge 1$, coupled to both external and internal heat baths of the Ornstein-Uhlenbeck type. The external heat baths, applied at the boundaries in the 1-direction, are at specified, unequal, temperatures \tlb and \trb. The temperatures of the internal baths are determined in a self-consistent way by the requirement that there be no net energy exchange with the system in the non-equilibrium stationary state (NESS). We prove the existence of such a stationary self-consistent profile of temperatures for a finite system and show it minimizes the entropy production to leading order in (\tlb -\trb). In the NESS the heat conductivity $\kappa$ is defined as the heat flux per unit area divided by the length of the system and (\tlb -\trb). In the limit when the temperatures of the external reservoirs goes to the same temperature $T$, $\kappa(T)$ is given by the Green-Kubo formula, evaluated in an equilibrium system coupled to reservoirs all having the temperature $T$. This $\kappa(T)$ remains bounded as the size of the system goes to infinity. We also show that the corresponding infinite system Green-Kubo formula yields a finite result. Stronger results are obtained under the assumption that the self-consistent profile remains bounded.Comment: to appear in J. Stat. Phy

Entwicklung und Ungleichheit von Fähigkeiten : Anmerkungen aus ökonomischer Sicht

Nirgends sonst im ökonomischen Handeln fallen Kosten und Nutzen im Zeitablauf und aufgeteilt nach Investoren und Nutznießern so eklatant auseinander wie bei Bildungsinvestitionen. In dem vorliegenden Beitrag wird argumentiert, dass in der sozialen Realität die Bildungsungleichheit im Vorschulalter eine der wichtigsten Ursachen für die Ungleichheit von Fähigkeiten und Kompetenzen auch im Schulalter und im Erwerbsleben ist. Für benachteiligte Kinder scheint somit die Bildungsungleichheit vor dem Schulalter bei uns, ebenso wie in anderen Ländern mit hohen Bildungsausgaben und hoher Wirtschaftskraft ihren schicksalhaften Charakter noch keineswegs verloren zu haben. Um dies zu ändern, bleibt es eine vordringliche Aufgabe auch der Bildungspolitik, den Zugang zu einer angemessenen emotionalen Fürsorge von Anfang an weiter zu verbessern. Darüber hinaus ist es notwendig, den betroffenen Kindern bis ins Jugendalter altersgemäß und individuell zur Seite zu stehen

Economic segregation and urban growth

Many studies have investigated the socioeconomic consequences of residential economic segregation in U.S. urban areas. These studies mainly focus on the impact of economic segregation on the poor or minorities and almost universally find that economic segregation hurts these groups in many ways. However, few studies investigate how economic segregation relates to the economic growth of an urban area as a whole. While there are papers that study this issue theoretically, empirical evidence is lacking. The motivation of this paper is to fill this gap. Using U.S. census data, this study documents a significant negative relationship between the initial levels of economic segregation in 1980 and the subsequent economic growth, indexed by metropolitan population growth, in 1980-2000 in U.S. metropolitan statistical areas (MSAs). Holding other things constant, MSAs having higher initial levels of economic segregation experienced substantially slower subsequent population growth