On the speed of convergence to stationarity of the Erlang loss system

We consider the Erlang loss system, characterized by $N$ servers, Poisson arrivals and exponential service times, and allow the arrival rate to be a function of $N.$ We discuss representations and bounds for the rate of convergence to stationarity of the number of customers in the system, and display some bounds for the total variation distance between the time-dependent and stationary distributions. We also pay attention to time-dependent rates

Dealing with change and uncertainty within the regulatory frameworks for flood defense infrastructure in selected European countries

Whereas existing literature on the interactions between law, adaptive governance and resilience in the water sector often focuses on quality or supply issues, this paper addresses adaptation in national water laws in relation to increasing flood risks. In particular, this paper analyzes the extent to which legal rules governing flood defense infrastructure in a selection of European countries (Sweden, France, England and the Netherlands) allow for response and adaptation to change and uncertainty. While there is evidence that the legal rules on the development of new infrastructure require that changing conditions be considered, the adaptation of existing infrastructure is a more complicated matter. Liability rules fail to adequately address damages resulting from causes external to the action or inaction of owners and managers, in particular extreme events. A trend towards clearer, and in some cases, increased public powers to ensure the safety of flood defense infrastructure is observed. The paper concludes that legal rules should ensure not only that decisions to build flood defenses are based on holistic and future-oriented assessments, but also that this is reflected in the implementation and operation of these structures

Sticks and carrots for reducing property-level risks from floods: an EU-US comparative perspective

In discussing legal and policy frameworks for flood risk management, the attention is often put on increasing resilience in public spaces. In terms of private properties, discussions are geared toward enhancing the adaptive capacity of future developments. This paper focuses on the instruments associated with resilience of existing privately owned residential buildings mainly from the perspective of post-flood policies and compensation regimes. The paper scrutinizes the relevant legal and policy landscapes in the United States, the European Union and two Member States – the UK and the Netherlands. The goal is to provide mutual lessons learned between the EU, its Member States, and the US and to set forth generally applicable recommendations for improving post-flood policies for existing buildings

Dealing with flood damages: will prevention, mitigation and ex-post compensation provide for a resilient triangle?

There is a wealth of literature on the design of ex-post compensation mechanisms for natural disasters. However, more research needs to be done on the manner in which these mechanisms could steer citizens toward adopting individual level preventive and protection measures in the face of flood risks. This paper provides a comparative legal analysis of the financial compensation mechanisms following floods, be it through insurance, public funds or a combination of both, with an empirical focus on Belgium, the Netherlands, England and France. Similarities and differences between the methods in which these compensation mechanisms for flood damages enhance resilience are analyzed. The comparative analysis especially focuses on the link between the recovery strategy on the one hand and prevention and mitigation strategies on the other. There is great potential within the recovery strategy for promoting preventive action, for example in terms of discouraging citizens from living in high-risk areas, or encouraging the uptake of mitigation measures, such as adaptive building. However, this large potential is yet to be realized, in part due to insufficient consideration and promotion of these connections within existing legal frameworks. Recommendations are made about how the linkages between strategies can be further improved. These recommendations relate to, amongst others, the promotion of resilient reinstatement through recovery mechanisms and the removal of legal barriers preventing the establishment of link-inducing measures

Keuzestress!?

In de media en de sociologie wordt steeds vaker de indruk gewekt dat hedendaagse individuen aan stress en frustratie ten onder gaan vanwege hun schijnbaar onbeperkte keuzevrijheid. Maar is dat zo? Mensen blijken keuzestress bij hun alledaagse keuzes op drie manieren te ondervangen

On the use of Kodak CR film for quality assurance of needle loading in I-125 seed prostate brachytherapy

Copyright © 2007 ACPSEM. All rights reserved.The document attached has been archived with permission from the publisher.Low dose rate brachytherapy using implanted I-125 seeds as a monotherapy for prostate cancer is now in use in many hospitals. In contrast to fractionated brachytherapy treatments, where the effect of incorrect positioning of the source in one treatment raction can be diminished by correcting the position in subsequent fractions, the I-125 seed implant is permanent, making correct positioning of the seeds in the prostate essential. The seeds are inserted into the prostate using needles. Correct configuration of seeds in the needles is essential in order to deliver the planned treatment. A comparison of an autoradiograph obtained by exposing film to the seed-loaded needles with the patient treatment plan is a valuable quality assurance tool. However, the time required to sufficiently expose Kodak XOMAT V film, currently used in this department is significant. This technical note presents the use of Kodak CR film for acquisition of the radiograph. The digital radiograph can be acquired significantly faster, has superior signal-to-noise ratio and contrast and has the usual benefits of digital film, e.g. a processing time which is shorter than that required for non-digital film, the possibility of image manipulation, possibility of paper printing and electronic storage.Lotte S. Fog, Ralph Nicholls and Tim van Door

Managing Entrepreneurial Orientation

In this dissertation, we evaluate the roles senior management teams and individual middle managers play in realizing the performance benefits of entrepreneurial orientations. We investigate the role of senior management teams by focusing on a sample of 9.000 firms in the Netherlands. The first study focuses on antecedents of entrepreneurial orientation, i.e. internal and external knowledge acquisition of senior management teams. We find that both internal and external knowledge acquisition are important and that a premium in terms of the entrepreneurial orientation of the firm may be obtained by simultaneously sourcing for both types of knowledge. Our second study presents a model for top management teams aiming to enhance the performance benefits of the entrepreneurial orientation of the firm. We investigate team attributes such as team heterogeneity and shared vision and find some compelling results with respect to their context specific applicability for leveraging the entrepreneurial orientation of the firm. Our final study, based within the European branch of a single firm operating at the intersection of hardware, software and IT consulting, examines the individual entrepreneurial orientation of middle managers and subsequent performance benefits. We find that strong network ties of relatively higher placed middle managers are instrumental for realizing the inherent value of entrepreneurial orientation. Together, our results emphasize the performance benefits that may be obtained if the entrepreneurial orientation of organizations and individuals is appropriately managed. Attention for knowledge acquisition, team composition, the environmental context as well as network ties and the hierarchical position of individual managers represent essential aspects of effective management of entrepreneurial orientations

Inferring the effect of species interactions on trait evolution

Models of trait evolution form an important part of macroevolutionary biology. The Brownian motion model and Ornstein-Uhlenbeck models have become classic (null) models of character evolution, in which species evolve independently. Recently, models incorporating species interactions have been developed, particularly involving competition where abiotic factors pull species toward an optimal trait value and competitive interactions drive the trait values apart. However, these models assume a fitness function rather than derive it from population dynamics and they do not consider dynamics of the trait variance. Here we develop a general coherent trait evolution framework where the fitness function is based on a model of population dynamics, and therefore it can, in principle, accommodate any type of species interaction. We illustrate our framework with a model of abundance-dependent competitive interactions against a macroevolutionary background encoded in a phylogenetic tree. We develop an inference tool based on Approximate Bayesian Computation and test it on simulated data (of traits at the tips). We find that inference performs well when the diversity predicted by the parameters equals the number of species in the phylogeny. We then fit the model to empirical data of baleen whale body lengths, using three different summary statistics, and compare it to a model without population dynamics and a model where competition depends on the total metabolic rate of the competitors. We show that the unweighted model performs best for the least informative summary statistic, while the model with competition weighted by the total metabolic rate fits the data slightly better than the other two models for the two more informative summary statistics. Regardless of the summary statistic used, the three models substantially differ in their predictions of the abundance distribution. Therefore, data on abundance distributions will allow us to better distinguish the models from one another, and infer the nature of species interactions. Thus our framework provides a conceptual approach to reveal species interactions underlying trait evolution and identifies the data needed to do so in practice.</p

Quorum sensing as a mechanism to harness the wisdom of the crowds

Bacteria release and sense small molecules called autoinducers in a process known as quorum sensing. The prevailing interpretation of quorum sensing is that by sensing autoinducer concentrations, bacteria estimate population density to regulate the expression of functions that are only beneficial when carried out by a sufficiently large number of cells. However, a major challenge to this interpretation is that the concentration of autoinducers strongly depends on the environment, often rendering autoinducer-based estimates of cell density unreliable. Here we propose an alternative interpretation of quorum sensing, where bacteria, by releasing and sensing autoinducers, harness social interactions to sense the environment as a collective. Using a computational model we show that this functionality can explain the evolution of quorum sensing and arises from individuals improving their estimation accuracy by pooling many imperfect estimates – analogous to the ‘wisdom of the crowds’ in decision theory. Importantly, our model reconciles the observed dependence of quorum sensing on both population density and the environment and explains why several quorum sensing systems regulate the production of private goods.</p

The European Union approach to flood risk management and improving societal resilience: lessons from the implementation of the Floods Directive in six European countries

Diversity in flood risk management approaches is often considered to be a strength. However in some national settings, and especially for transboundary rivers, variability and the incompatibility of approaches can reduce the effectiveness of flood risk management. Placed in the context of increasing flood risks, as well as the potential for flooding to undermine the European Union's sustainable development goals, a desire to increase societal resilience to flooding has prompted the introduction of a common European Framework. This paper provides a legal and policy analysis of the implementation of the Floods Directive (2007/60/EC) in six countries; Belgium (Flemish Region), England, France, the Netherlands, Poland and Sweden. Evaluation criteria from existing legal and policy literature frame the study of the Directive and its impact on enhancing or constraining societal resilience by using an adaptive governance approach. These criteria are initially used to analyze the key components of the EU approach, before providing insight of the implementation of the Directive at a national level. Similarities and differences in the legal translation of European goals into existing flood risk management are analyzed alongside their relative influence on policy and practice. The research highlights that the impact of the Floods Directive on increasing societal resilience has been nationally variable, in part due to its focus on procedural obligations, rather than on more substantive requirements. Analysis shows that despite a focus on transboundary river basin management, in some cases existing traditions of flood risk management, have overridden objectives to harmonize flood risk management. This could be strengthened by requiring more stringent cooperation and providing the competent authorities in International River Basins Districts with more power. Despite some shortcomings in directly impacting flood risk outcomes, the Directive has positively stimulated discussion and flood risk management planning in countries that were perhaps lagging behind