Time scale in concrete fracture: a model based on partitions of unity

Intense research efforts have been put in the formulation of theories for crack initiation and propagation in concrete. Yet, little attention has been paid to the time-dependence of fracture, despite evidence of its significance. This paper reports a finite element model which captures the time scale in concrete fracture. Visco-elasticity is employed to capture bulk creep. In the fracture process zone a different time scale acts. Therefore, a rate-dependent cracking resistance is modelled. A recently developed finite element method for modelling cohesive cracks is employed. It is based on partitions of unity, by which means displacement jumps are introduced independently of the mesh structure. This avoids the requirement of dense meshes by regularised continuum approaches to model localisation, and a priori knowledge of where cracks occur for standard discrete cracking approaches via interfaces

GINI DP 5: Household Joblessness and its Impacts on Poverty and Deprivation in Europe

Working-age households where no-one is in work have become an increasing focus of policy concern even before the economic crisis, and the EU has included household joblessness in its new poverty reduction target for 2020. This paper focuses on the variation across EU countries in the prevalence of household joblessness and its impact on income poverty and deprivation, and on the implications for the new EU poverty reduction target. It brings out fi rst that there are some divergences across key data sources in the extent of joblessness. The prevalence of household joblessness varies substantially across EU countries, but there is little evidence of a consistent pattern among groupings of countries often categorised together in terms of welfare regime or geographically. In aggregate there is little association between the overall extent of household joblessness in a country and the percentage in relative income poverty or above a material deprivation threshold. At micro level, being in a jobless household has a substantial impact on the likelihood of being in relative income poverty or deprived, but the scale of these impacts is shown to be very much greater in some countries than in others, and to vary between single-adult and multiple-adult households. In most EU countries little more than half the working age adults in jobless households are either income poor or deprived, so including joblessness in the poverty reduction target does make a difference, without a clearly-articulated rationale.

WP 103 - Separate, joint or integrated?

This paper analyses the integration of active labour market policies for two groups of unemployed from a theoretical perspective. In general a model with only one type of agent performs better than a model with two types of agents. If there are two types of agents part of the effort of one agent leaks away to the other agent and decreases the incentives to get the unemployed back to work. A model where two agents work together and serve both types of unemployed performs even worse. This is because they are only partially compensated for their effort, which decreases the incentives to get the unemployed back to work even more.

Straightforward Synthesis of α,β-Unsaturated Thioesters via Ruthenium-Catalyzed Olefin Cross-Metathesis with Thioacrylate

The cross-metathesis reaction of S-ethyl thioacrylate with a variety of olefins is effectively catalyzed by using a ruthenium benzylidene olefin metathesis catalyst. This reaction provides a convenient and versatile route to substituted α,β-unsaturated thioesters, key building blocks in organic synthesis.

Features of reproduction and assisted reproduction in the white (Ceratotherium simum) and black (Diceros bicornis) rhinoceros

Despite the worldwide increase of rhinoceros calf numbers, the growth of the population of white and black rhinoceros is slowing down mainly due to anthropogenic causes, such as poaching and habitat loss. Assisted reproduction is one of the methods of preserving the valuable genomes of these animals from being lost, and assists in breeding them in captivity to maintain the specie(s) numbers and provide an option for possible reintroduction into the wild. Since wild rhinoceros are difficult to handle and examine clinically, most of the current information available on their reproductive characteristics has been gained from captive rhinoceros populations. Nevertheless, very little is known about rhinoceros reproduction. Since the rhinoceros belongs to the odd-toed ungulates (Perissodactyls) group, like the horse and the tapir, the horse has been proposed as a suitable model to study reproduction and artificial reproductive techniques in the rhinoceros. In this review, the current knowledge of the reproduction of the rhinoceros is summarized

Stepping-stones for the unemployed: The effect of temporary jobs on the duration until regular work

Individual labour market transitions from unemployment into temporary work are often succeeded by a transition from temporary into regular work. We investigate whether temporary work increases the transition rate to regular work. In that case, temporary work may enhance labour market efficiency. We use longitudinal survey data of individuals to estimate a multi-state duration model, applying the “timing of events” approach. To deal with selectivity, the model incorporates transitions from unemployment to temporary jobs and unobserved determinants of the transition rates. The data contain multiple spells in labour market states at the individual level. We analyse the results using novel graphical representations. The results unambiguously show that temporary jobs serve as stepping-stones towards regular employment. They shorten the duration of unemployment and they substantially increase the fraction of unemployed workers who have regular work within a few years after entry into unemployment, as compared to a situation without temporary jobs.Unemployment; fixed term contracts; temporary work; job search; duration model; treatment effect