Spore contamination of Tilletia tritici in seed lots as affected by field disease incidence

Seed lots normally become contaminated by spores of the seed borne common bunt (Tilletia tritici) during harvest of fields with infected plants. To demonstrate the relation between the number of infected plants in the field and the resulting number of spores in the harvested seed lot, a fixed number of infected tillers were placed in uncontaminated wheat fields. Two field experiments show that the number of spores in the seed lot is proportional to the number of infected plants in the field. Only 3% of the spores from the infected plants in the field end up in the seed lot after harvest with a combine harvester. However, only few spores in a seed lot is enough to establish infection in the next year field, and with a threshold of 10 spores/g seed which is the current threshold for untreated seed in Denmark, less than 1 infected tiller per 1000 m2 can be accepted in a field aimed for propagation

The Mean Variance Mixing GARCH (1,1) model

Here we present a general framework for a GARCH (1,1) type of process with innovations with a probability law of the mean- variance mixing type, therefore we call the process in question the mean variance mixing GARCH \ (1,1) or MVM GARCH\(1,1). One implication is a GARCH\ model with skewed innovations and constant mean dynamics. This is achieved without using a location parameter to compensate for time dependence that affects the mean dynamics. From a probabilistic viewpoint the idea is straightforward. We just construct our stochastic process from the desired behavior of the cumulants. Further we provide explicit expressions for the unconditional second to fourth cumulants for the process in question. In the paper we present a specification of the MVM-GARCH process where the mixing variable is of the inverse Gaussian type. On the basis on this assumption we can formulate a maximum likelihood based approach for estimating the process closely related to the approach used to estimate an ordinary GARCH (1,1). Under the distributional assumption that the mixing random process is an inverse Gaussian i.i.d process the MVM-GARCH process is then estimated on log return data from the Standard and Poor 500 index. An analysis for the conditional skewness and kurtosis implied by the process is also presented in the paperGARCH Skewness Conditional Skewness

Evaluation of Nordic heritage varieties and NILs for resistance to common bunt (Tilletia caries syn. T.tritici)

A number og wheat varieties from NordGen and Allkorn were tested fro susceptibility to common bunt. Most were susceptible to common bunt which is in line with other screening experiments of randomly selected varieties. However, a few lines not previously known to be resistant were shown to have different resistance genes. None of them however were resistant to all the virulence races tested. NILs developed by MacKey were evaluated and there seem to be a potential for using some of them as differential lines for resistance gene Bt1, Bt5, and Bt9. Purification based on resistant head rows may also develop NILs with resistance to Bt6 and Bt10 and possible also Bt7 from NGB16160. A crossing program of the remaining Bt-genes was started in 2016. The NILs may be used also to support development of genetic markers of the resistance genes

Job-search Incentives From Labour Market Programs - an Empirical Analysis

In this paper we examine whether the prospect of compulsory programme participation motivates individuals to leave the unemployment insurance (UI) system prior to participation. We analyze data from the Danish labour market. Here a series of reforms have enforced program participation and gradually restricted the duration of unemployment before individuals must enroll into programmes. However, there is substantial heterogeneity in enrollment probabilities. If individuals want to avoid participation and observe the heterogeneity in participation, this will also affect their search behaviour. We estimate a model for anticipatory effects of participation, allowing for heterogeneity, on search behaviour and find large significant effects from anticipation of enrollment on the exit probability out of unemployment.active labour market measures; hazard rates; unobserved heterogeneity

Approximating the probability distribution of functions of random variables: A new approach

We introduce a new approximation method for the distribution of functions of random variables that are real-valued. The approximation involves moment matching and exploits properties of the class of normal inverse Gaussian distributions. In the paper we we examine the how well the different approximation methods can capture the tail behavior of a function of random variables relative each other. This is obtain done by simulate a number functions of random variables and then investigate the tail behavior for each method. Further we also focus on the regions of unimodality and positive definiteness of the different approximation methods. We show that the new method provides equal or better approximations than Gram-Charlier and Edgeworth expansioApproximation of random variables

Does Active Labour Market Policy Work? Lessons from the Swedish Experiences

The Swedish experiences of the 1990s provide a unique example of how large-scale active labour market programmes (ALMPs) have been used as a means to fight high unemployment. This paper surveys the empirical studies of the effects of ALMPs in Sweden. On the whole, ALMPs have probably reduced open unemployment, but also reduced regular employment. The overall policy conclusion is that ALMPs of the scale used in Sweden in the 1990s are not an efficient means of employment policy. To be effective, ALMPs should be used on a smaller scale.

Inequality and Mobility of Wealth in Sweden 1983/84 - 1992/93.

Using longitudinal data which include real estate wealth, financial assets as well as consumer durables, changes in the distribution of wealth in Sweden are related to major changes in asset prices and in incentives to hold various assets in the 1980s and the beginning of the 1990s. Our analysis of the mobility of wealth indicates that mobility is higher in Sweden than in the United States, while the analysis of who is gaining and who is loosing shows results similar to those of previous studies.

Approximating the Probability Distribution of Functions of Random Variables: A New Approach

We introduce a new approximation method for the distribution of functions of random variables that are real-valued. The approximation involves moment matching and exploits properties of the class of normal inverse Gaussian distributions. In the paper we examine the how well the different approximation methods can capture the tail behavior of a function of random variables relative each other. This is done by simulate a number functions of random variables and then investigate the tail behavior for each method. Further we also focus on the regions of unimodality and positive definiteness of the different approximation methods. We show that the new method provides equal or better approximations than Gram-Charlier and Edgeworth expansions. Nous introduisons une nouvelle méthode pour approximer la distribution de variables aléatoires. L'approximation est basée sur la classe de distribution normale inverse gaussienne. On démontre que la nouvelle approximation est meilleure que les expansions Gram-Charlier et Edgeworth.normal inverse Gaussian, Edgeworth expansions, Gram-Charlier, distribution normale inverse gaussienne, expansions d'Edgeworth, Gram-Charlier

Does Active Labour Market Policy Work? Lessons from the Swedish Experiences

The Swedish experiences of the 1990s provide a unique example of how large-scale active labour market programmes (ALMPs) have been used as a means to fight high unemployment. This paper discusses the mechanisms through which ALMPs affect (un)employment and surveys the empirical studies of the effects of ALMPs in Sweden. The main conclusions are: (i) there is hardly any evidence for a positive effect on matching efficiency; (ii) there are some indications of positive effects on labour force participation; (iii) subsidised employment seems to cause displacement of regular employment, whereas this appears not to be the case for labour market training; (iv) it is unclear whether or not ALMPs raise aggregate wage pressure in the economy; (v) in the 1990s, training programmes seem not to have enhanced the employment probabilities of participants, whereas some forms of subsidised employment seem to have had such effects; and (vi) youth programmes seem to have caused substantial displacement effects at the same time as the gains for participants appear uncertain. On the whole, ALMPs have probably reduced open unemployment, but also reduced regular employment. The overall policy conclusion is that ALMPs of the scale used in Sweden in the 1990s are not an efficient means of employment policy. To be effective, ALMPs should be used on a smaller scale. There should be a greater emphasis on holding down long-term unemployment in general and a smaller emphasis on youth programmes. ALMPs should not be used as a means to renew unemployment benefit eligibility.Active; Labour; Market; Policy