Local Variation as a Statistical Hypothesis Test

The goal of image oversegmentation is to divide an image into several pieces, each of which should ideally be part of an object. One of the simplest and yet most effective oversegmentation algorithms is known as local variation (LV) (Felzenszwalb and Huttenlocher 2004). In this work, we study this algorithm and show that algorithms similar to LV can be devised by applying different statistical models and decisions, thus providing further theoretical justification and a well-founded explanation for the unexpected high performance of the LV approach. Some of these algorithms are based on statistics of natural images and on a hypothesis testing decision; we denote these algorithms probabilistic local variation (pLV). The best pLV algorithm, which relies on censored estimation, presents state-of-the-art results while keeping the same computational complexity of the LV algorithm

Overschooling and unemployment

Although overschooling is regarded as the result of imperfect allocation in the labour market, hardly any attention has been given to the influence of another imperfection, unemployment. Several researchers report about an increasing incidence of overschooling in the Netherlands. Although a lot of research has been done in the Netherlands on overschooling, this is not a phenomenon restricted to the Netherlands. Overschooling was found and measured in the United States, Germany, Spain, Portugal the United Kingdom and may be around in other Western European countries as well. Remarkably, however, is that in this line of research no attention has been paid to the effect of unemployment on overschooling. Because it can be argued that almost all unemployed are overschooled, the incidence and amount of overschooling and its rate of return should be directly affected by the unemployment rate in a country. However for the Netherlands we cannot find a relation between the unemployment rate and the amount of overschooling. The amount of overschooling is in 1998, a year with low unemployment, as high as in 1985, a year with high unemployment. After correcting the selectivity bias, caused by the unemployed, we also do not find changes in the rate of return on education, suggesting that wages in the Netherlands are rather sticky. Therefore efficiency wage theory seems to be a better candidate in explaining overschooling than a matching model as propesed by Hartog.

Are we making real progress in computer vision today?

AbstractThis paper presents an opinion on research progress in computer vision

Theoretical study on the protonation of AZA-aromatics

The protonation of azanaphthalenes and azabenzenes has been studied theoretically using CNDO/2 wavefunctions and perturbation theory in order to examine the correlation between pKa values and quantum-mechanical quantities

Higher education reform: getting the incentives right

This study is a joint effort by the Netherlands Bureau for Economic Policy Analysis (CPB) and the Center for Higher Education Policy Studies. It analyses a number of `best practices¿ where the design of financial incentives working on the system level of higher education is concerned. In Chapter 1, an overview of some of the characteristics of the Dutch higher education sector is presented. Chapter 2 is a refresher on the economics of higher education. Chapter 3 is about the Australian Higher Education Contribution Scheme (HECS). Chapter 4 is about tuition fees and admission policies in US universities. Chapter 5 looks at the funding of Danish universities through the so-called taximeter-model, that links funding to student performance. Chapter 6 deals with research funding in the UK university system, where research assessments exercises underlie the funding decisions. In Chapter 7 we study the impact of university-industry ties on academic research by examining the US policies on increasing knowledge transfer between universities and the private sector. Finally, Chapter 8 presents food for thought for Dutch policymakers: what lessons can be learned from our international comparison

Granular fountains: Convection cascade in a compartmentalized granular gas

This paper extends the two-compartment granular fountain [D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse, Phys. Rev. Lett. 92, 184301 (2004)] to an arbitrary number of compartments: The tendency of a granular gas to form clusters is exploited to generate spontaneous convective currents, with particles going down in the well-filled compartments and going up in the diluted ones. We focus upon the bifurcation diagram of the general K-compartment system, which is constructed using a dynamical flux model and which proves to agree quantitatively with results from molecular dynamics simulations

Diazanaphthalenes: A 13C NMR investigation on the site of protonation and pKa values

The pH dependence of the 13C chemical shifts (δ) of the diazanaphthalenes has been recorded. From this dependence the pKa values have been determined using the Henderson-Hasselbach equation. The change in 13C chemical shifts under the influence of nitrogen protonation (Δδ) has been predicted using the Δδ values of quinoline and isoquinoline. The correlation between observed and expected Δδ values of the symmetric diazanaphthalenes is very good. Assuming these changes in chemical shifts to be of general validity, the site of protonation in the asymmetric diazanaphthalenes has been determined by comparison of the expected Δδ values for α- and ß-nitrogen protonation with the observed ones. The site of protonation for 1,6- and 1,7-naphthyridine is the ß-nitrogen atom, whereas for cinnoline both monoprotonated species are present in a significant amount