Lossy gossip and composition of metrics

We study the monoid generated by n-by-n distance matrices under tropical (or min-plus) multiplication. Using the tropical geometry of the orthogonal group, we prove that this monoid is a finite polyhedral fan of dimension n(n-1)/2, and we compute the structure of this fan for n up to 5. The monoid captures gossip among n gossipers over lossy phone lines, and contains the gossip monoid over ordinary phone lines as a submonoid. We prove several new results about this submonoid, as well. In particular, we establish a sharp bound on chains of calls in each of which someone learns something new.Comment: Minor textual edits, final versio

On the relationship between firm age and productivity growth

For young firms, a clear relationship exists between firm age and productivity. Various studies have shown that the productivity level of new firms is below the average level, while the productivity growth rate of (surviving) young firms is above average. During the first few years, the average level of productivity tends to increase while the average growth rate tends to decrease. For elder, established firms, the relationship between age and productivity becomes less clear. Established firms show on average a positive growth rate, but whether this growth rate is related to the specific age of these firms is not well established. In this study we examine the relationship between the age of firms and their productivity growth, for establishes firms, where establishes firms are defined as firms of at least 10 years of age. Our research question is: to which extent are differences in productivity growth rates between individual firms related to firm age?

Can firm age account for productivity differences?

The productivity of enterprises is an important indicator, for individual enterprises as well as for policy makers. For individual firms, their productivity is a main determinant of their performance, while the aggregate productivity is one of the main determinants of economic growth. In this study we examine the relationship between the age of firms and the level and growth rate of productivity, focusing on firms of at least 10 years of age. For these firms, we will examine the following two research questions: How does the distribution of firm productivity (as characterised by mean and standard deviation) change over age cohorts? To which extent are differences in productivity between individual firms related to firm age?

Time requirements for administrative activities; an investigation into firm size effects

This paper examines the assumption that activity time is independent of firm size (measured by the number of employees). Existing theories on (dis)economies of scale and scope and wage differentials are unclear on what to expect. For relatively complex activities such as becoming familiar with information obligations or checking agreements and declarations, the activity time might be related to the number of employees. For activities such as receiving, copying and sending information and documents, no theoretical arguments have been identified that suggest a firm-size effect. For the empirical examination of the existence of a relationship between firm size and activity time, data is used that were gathered in two projects applying the MISTRAL approach. This results in a dataset with information on many different activities, with only a few observations for each activity. By using a relative measure for activity time, observations for different activities can be combined in the analysis. To this end, relative activity time is defined as the ratio between the measured activity time and the standardized activity time for a certain activity. The empirical results suggest that, within the examined policy areas, firm size has no noticeable relationship with activity times. First of all, there exists no significant difference in average relative activity time between firms of different size classes. There are also no significant correlations between these variables. Next, these results are confirmed by regression analysis, where relative activity time is estimated as a function of firm size and other variables that might be of influence on activity time (such as experience of employees, the presence of a specific department for administrative activities, and whether additional adaptations and/or computations are required for a specific activity). Relative activity time tends to be higher for activities that require additional adaptations, but is independent of the size of the firm.

Semiconducting polymers for light-emitting diodes and lasers:a structural, photophysical and electrical study of PPV-type alternating copolymers and oligomers

pi-conjugated polymers attract much interest nowadays for use as active component in electronic, optical and optoelectronic applications,like light-emitting diodes, lightemitting electrochemical cells, photodiodes, photovoltaic cells, field-effect transistors, optocouplers and optically pumped lasers. ... Zie: Summary