Factorization of symplectic matrices into elementary factors

We prove that a symplectic matrix with entries in a ring with Bass stable rank one can be factored as a product of elementary symplectic matrices. This also holds for null-homotopic symplectic matrices with entries in a Banach algebra or in the ring of complex valued continuous functions on a finite dimensional normal topological space.Comment: 9 page

Controlled surgery with trivial local fundamental groups

We provide a proof of the controlled surgery sequence, including stability, in the special case that the local fundamental groups are trivial. Stability is a key ingredient in the construction of exotic homology manifolds by Bryant, Ferry, Mio and Weinberger, but no proof has been available. The development given here is based on work of M. Yamasaki.Comment: 5 page

The demand for higher education in the Netherlands 1950-'99

This paper investigates the role of economic factors in the university enrollment decision for the post-war period in the Netherlands. We include those factors standing at the heart of the idea that education is an investment. Collecting student enrollment data for eight subject categories results in a large data set, as a cross-section dimension is added to the time-series. The econometric results suggest that students are not responsive to tuition fees, but financial support (the sum of loans and grants), the college premium on future labour market earnings, and the alternative wage are important in the enrollment decision.

Agglomeration economies and entrepreneurship: testing for spatial externalities in the Dutch ICT industry

Although there is growing evidence on the role of agglomeration economies in the formation and growth of firms, both the concepts of agglomeration economies and entrepreneurship tend to be ambiguously defined and measured in the literature. In this study, we aim to improve the conceptualisations and measures of agglomeration economies and entrepreneurship. Indicators of agglomeration economies are analysed in clearly defined urban regimes on three spatial scales in the Netherlands – national zoning, labour market connectedness, and urban size. This is done in order to uncover their effect on two entrepreneurial phases in the firm life cycle - new firm formation and the growth of incumbent firms in the relatively new ICT industry in the Netherlands. In comparison with new firm formation, the growth of incumbent firms is not so much related to spatial clustering of the ICT industry and other localized sources of knowledge economies associated with urban density. Instead, knowledge as an input for growth of incumbent firms is associated with more endogenous (firm internal) learning aspects, reflected by a significant correlate with R&D-investments. Also the effect of local ICT firm competition differs between the two types of firms: a positive effect on new firm formation, but a negative effect on incumbent firm growth. In general, agglomeration economies have stronger effects on the formation of ICT firms than on the growth of ICT firms.agglomeration economics, spatial externalities, entrepreneurship, location, urban regimes, ICT industry

Investment performance and market share : a study of the German mutual fund industry

We study a set of German open-end mutual funds for a time period during which this industry emerged from its infancy. In those years, the distribution channel for mutual funds was dominated by the brick-and-mortar retail networks of the large universal banks. Using monthly observations from 12/1986 through 12/1998, we investigate if cross-sectional return differences across mutual funds affect their market shares. Although such a causal relation has been established in highly competitive markets, such as the United States, the rigid distribution system in place in Germany at the time may have caused retail performance and investment performance to uncouple. In fact, although we observe stark differences in investment performance across mutual funds (and over time), we find no evidence that cross-sectional performance differences affect the market shares of these funds. Klassifikation: G 2

Performance and market share: evidence from the German mutual fund industry

In this paper we analyze the relation between fund performance and market share. Using three performance measures we first establish that significant differences in the risk-adjusted returns of the funds in the sample exist. Thus, investors may react to past fund performance when making their investment decisions. We estimated a model relating past performance to changes in market share and found that past performance has a significant positive effect on market share. The results of a specification test indicate that investors react to risk-adjusted returns rather than to raw returns. This suggests that investors may be more sophisticated than is often assumed

A Two-Dimensional Signal Space for Intensity-Modulated Channels

A two-dimensional signal space for intensity- modulated channels is presented. Modulation formats using this signal space are designed to maximize the minimum distance between signal points while satisfying average and peak power constraints. The uncoded, high-signal-to-noise ratio, power and spectral efficiencies are compared to those of the best known formats. The new formats are simpler than existing subcarrier formats, and are superior if the bandwidth is measured as 90% in-band power. Existing subcarrier formats are better if the bandwidth is measured as 99% in-band power.Comment: Submitted to IEEE Communications Letters, Feb. 201