Dynamic Effects of Trust and Cognitive Social Structures on Information Transfer Relationships

Changes in relationships are due to human actions. We assume that these human actions are functions of perceptions of a focal individual, but also the perceptions of other individuals who are part of the organizational and social environment. We hypothesize that perceptions based trust and perceptions of the structural environment individuals operate in affect relationship change more than the "actual" environment in which individuals operate. An empirically analysis shows the dynamic effects of perceptions on changes in two types of relationships, which are believed to be important in account management. We explore, 1, whether the levels of perceptions, and, 2, whether changes in perceptions affect relationship changes. For example, we consider the effects of the amount of trust as well as the change in the amount of trust one individual puts in another individual. We find that perceptions have more impact on relationship change than "actual" network variables have. Furthermore, the results show that it is useful to distinguish between level and change effects of perceptions.trust;dynamic cognitive social structures;network theory;relationship development

Greening Supply Chains: Impact on Cost and Design

The consideration of environmental issues has emerged as a topic of critical importance for today’s globalized supply chains. The purpose of this paper is to develop a strategic-tactical decision-support methodology to assist managers in evaluating the impact of environmental issues, related to transportation emissions, on the transport geography of a region. Specifically we provide a tool that addresses: (i) supply chain network design, including port of entry and transportation mode, and (ii) decisions on leasing vs. outsourcing of transportation and distribution centers. The applicability of the proposed methodology is examined through the development of a sustainable supply chain network in the South-Eastern Europe region. The results indicate that in most cases outsourcing distribution centers to Third Party Logistics operators improves both the cost and the environmental performance of a company. In all cases outsourcing of transportation operations minimizes the amount of CO2 and PM emissions generated, while leasing minimizes costs.carbon footprint;supply chain design;supply chain sustainability

An Equilibrium-Correction Model for Dynamic Network Data

We propose a two-stage MRQAP to analyze dynamic network data, within the framework of an equilibrium-correction (EC) model. Extensive simulation results indicate practical relevance of our method and its improvement over standard OLS. An empirical illustration additionally shows that the EC model yields interpretable parameters, in contrast to an unrestricted dynamic model.cognitive social structures;consistent accuracy;network centrality;structural autocorrelation;two-stage equilibrium model

Absence of magnetically-induced fractional quantization in atomic contacts

Using the mechanically controlled break junction technique at low temperatures and under cryogenic vacuum conditions we have studied atomic contacts of several magnetic (Fe, Co and Ni) and non-magnetic (Pt) metals, which recently were claimed to show fractional conductance quantization. In the case of pure metals we see no quantization of the conductance nor half-quantization, even when high magnetic fields are applied. On the other hand, features in the conductance similar to (fractional) quantization are observed when the contact is exposed to gas molecules. Furthermore, the absence of fractional quantization when the contact is bridged by H_2 indicates the current is never fully polarized for the metals studied here. Our results are in agreement with recent model calculations.Comment: 4 pages, 3 figure

Hunting tactics of Peregrines and other falcons

De slechtvalk was bijna uitgestorven door giftige residu’s van landbouwchemicaliën, maar de stand heeft zich hersteld. Dekker deed onderzoek naar de invloed van de terugkeer van deze roofvogel op zijn prooisoorten in Nederland en Canada. Hij heeft gegevens verzameld van 44 jaar, in alle seizoenen en in acht verschillende Canadese landschappen, alsmede aan de Friese waddenkust. In totaal zag hij slechtvalken 470 prooien slaan. Daarvan bestond 85 procent uit watervogels. Daarnaast werden er 104 prooien gepakt door drie andere valkensoorten uit deze studie: het smelleken, de giervalk en de prairievalk. Het jachtsucces van trekkende of overwinterende slechtvalken varieerde van zeven tot twaalf procent

Hubbard ladders in a magnetic field

The behavior of a two leg Hubbard ladder in the presence of a magnetic field is studied by means of Abelian bosonization. We predict the appearance of a new (doping dependent) plateau in the magnetization curve of a doped 2-leg spin ladder in a wide range of couplings. We also discuss the extension to N-leg Hubbard ladders

Hybrid Meta-Heuristics for Robust Scheduling

The production and delivery of rapidly perishable goods in distributed supply networks involves a number of tightly coupled decision and optimization problems regarding the just-in-time production scheduling and the routing of the delivery vehicles in order to satisfy strict customer specified time-windows. Besides dealing with the typical combinatorial complexity related to activity assignment and synchronization, effective methods must also provide robust schedules, coping with the stochastic perturbations (typically transportation delays) affecting the distribution process. In this paper, we propose a novel metaheuristic approach for robust scheduling. Our approach integrates mathematical programming, multi-objective evolutionary computation, and problem-specific constructive heuristics. The optimization algorithm returns a set of solutions with different cost and risk tradeoffs, allowing the analyst to adapt the planning depending on the attitude to risk. The effectiveness of the approach is demonstrated by a real-world case concerning the production and distribution of ready-mixed concrete.Meta-Heuristics;Multi-Objective Genetic Optimization;Robust Scheduling;Supply Networks