A Continuum,O(N) Monte-Carlo algorithm for charged particles

We introduce a Monte-Carlo algorithm for the simulation of charged particles moving in the continuum. Electrostatic interactions are not instantaneous as in conventional approaches, but are mediated by a constrained, diffusing electric field on an interpolating lattice. We discuss the theoretical justifications of the algorithm and show that it efficiently equilibrates model polyelectrolytes and polar fluids. In order to reduce lattice artifacts that arise from the interpolation of charges to the grid we implement a local, dynamic subtraction algorithm. This dynamic scheme is completely general and can also be used with other Coulomb codes, such as multigrid based methods

Phase fluctuations and first-order correlation functions of dissipative Bose-Einstein condensates

We investigate the finite lifetime effects on first-order correlation functions of dissipative Bose-Einstein condensates. By taking into account the phase fluctuations up to all orders, we show that the finite lifetime effects are neglible for the spatial first-order correlation functions, but have an important effect on the temporal correlations. As an application, we calculate the one-particle density matrix of a quasi-condensate of photons. Finally, we also consider the photons in the normal state and we demonstrate that the finite lifetime effects decrease both the spatial and temporal first-order correlation functions.Comment: 8 pages, 5 figure

Schwinger-Keldysh theory for Bose-Einstein condensation of photons in a dye-filled optical microcavity

We consider Bose-Einstein condensation of photons in an optical cavity filled with dye molecules that are excited by laser light. By using the Schwinger-Keldysh formalism we derive a Langevin field equation that describes the dynamics of the photon gas, and in particular its equilibrium properties and relaxation towards equilibrium. Furthermore we show that the finite lifetime effects of the photons are captured in a single dimensionless damping parameter, that depends on the power of the external laser pumping the dye. Finally, as applications of our theory we determine spectral functions and collective modes of the photon gas in both the normal and the Bose-Einstein condensed phase

Vis en visserij in het IJsselmeergebied

Het visbestand in het IJsselmeer wordt sterk bepaald door de intensieve visserijactiviteiten. Het IJsselmeer biedt goede potenties voor trekkende en (nu nog) zeldzame vissoorten, zeker wanneer de dynamische aspecten van een estuarium meer kunnen worden ontwikkel

Preparing for new competitive challenges: special issue on the 24th annual IPSERA conference

The 24st IPSERA conference in Amsterdam addressed the various new competitive challenges organizations face now that business environments are changing. While we can observe an increased role of - but also an increased concentration in - logistic services and IT services acting as a bonding agent of the various business processes, we also see an increased specialisation among suppliers, resulting in roles like capacity supplier, co-maker and broker. In terms of Systems Thinking: the subsystem of ‘Suppliers’ is breaking up into three sub-systems with distinctive different characteristics, and the traditional sub-system ‘Purchasing’ has transformed into an aspect-system connecting or involving all other sub-systems, while similarly, ‘Logistics’ and ‘IT’ have developed into intertwined aspect-systems, being part of each and every sub-system. These transformations have increased managerial complexity, greatly influencing the purchasing and supply chain functions within firms. The seven papers selected from the conference examine seven aspects of those changes in detail and elaborate on the role of the PSM field in this process: PSM answers to challenges by providing answers on how to move forward in practice

Consumer behaviour and order fulfilment in online retailing – a systematic review

This paper provides a systematic review of consumer behaviour and order fulfilment in online retailing. The objective of this review is threefold: first, to identify elements of order‐fulfilment operations that are relevant to online consumer behaviour (purchase, repurchase, product return); second, to understand the relationship between order‐fulfilment performance and consumer behaviour; and third, to inspire future research on developing consumer service strategies that takes account of these behavioural responses to order‐fulfilment performance outcomes. The paper is based on a systematic review of literature on online consumer behaviour and order‐fulfilment operations, mainly in the fields of marketing and operations, published in international peer‐reviewed journals between 2000 and September 2015. This study indicates that the current literature on online consumer behaviour focuses mainly on the use of marketing tools to improve consumer service levels. Very little research has been conducted on the use of consumer service instruments to steer consumer behaviour or, consequently, to manage related order‐fulfilment activities better. The study culminates in a framework that encompasses elements of order‐fulfilment operations and their relationship to online consumer behaviour. This paper is the first comprehensive review of online consumer behaviour that takes aspects of order‐fulfilment operations into account from both marketing and operations perspectives

Ecologically friendly sourcing in developing countries: a non-food case study

The purpose of this paper is to investigate how nearby sourcing versus long-distance sourcing affects the ecological friendliness - operationalized in terms of energy efficiency - of a supply chain for a non-food item in a developing country. Using case research, we show that the average energy needed to supply a pair of imported shoes to a retailer in Morocco is less than the average energy needed to supply a pair of locally produced shoes. These findings highlight the need to assess the true total energy effects of nearby sourcing versus long-distance sourcing since the outcomes of such assessments may be more complicated than they appear upon first glance, particularly in developing countries

Performance management practices in humanitarian organisations

Purpose – We examine how design and implementation practices for supply chain performance management that have proven successful in commercial organisations apply to Humanitarian Organisations (HOs) to guide the process of designing and implementing performance management in humanitarian organisations. Design/methodology/approach – We identify from the literature 10 successful practices regarding the design and implementation of supply chain performance management in commercial businesses. We apply these, using action research over a four-year period, at Médecins sans Frontières (MSF) Belgium and draw conclusions from this. Findings – We find that tools and techniques, such as workshops and technical sheets, are essential in designing and implementing supply chain performance measurement projects at HOs. Furthermore, making a link to an IT project is crucial when implementing performance measurement systems at HOs. Overall, our case study shows that performance management practices used in business can be applied and are relevant for humanitarian supply chains. Originality/value – Previous research has argued that there are few empirical studies in the domain of performance management at humanitarian organisations. To the best of our knowledge, this paper is the first to provide a longitudinal understanding of the design and implementation of supply chain performance measurement at HOs