Reconstructing conductivities with boundary corrected D-bar method

The aim of electrical impedance tomography is to form an image of the conductivity distribution inside an unknown body using electric boundary measurements. The computation of the image from measurement data is a non-linear ill-posed inverse problem and calls for a special regularized algorithm. One such algorithm, the so-called D-bar method, is improved in this work by introducing new computational steps that remove the so far necessary requirement that the conductivity should be constant near the boundary. The numerical experiments presented suggest two conclusions. First, for most conductivities arising in medical imaging, it seems the previous approach of using a best possible constant near the boundary is sufficient. Second, for conductivities that have high contrast features at the boundary, the new approach produces reconstructions with smaller quantitative error and with better visual quality

THE RELEVANCE OF PSYCHOLOGY THEORIES TO FINANCIAL ACCOUNTING

Starting from the interest that we have found in psychology sciences in order to understand better the way managers, analysts and last but not least investors behave in the decision making process our study focuses on the link between financial reporting, disclosure policies and investors judgment under uncertainty. The theoretical background describes the rational judgment of investors found in economic utility theories but also looks upon the main cognitive and social psychology for irrational behavior in the decision making process. Our research mainly focuses on measuring the influence of five psychological factors on the irrational behavior of potential investor. We showed that overconfidence occurs when investors overestimate the precision of their private signals and their knowledge about the value of a financial transaction and always remember the successfully times and easily forget the failures. Also, we have pointed out that limited attention is frequently associated with changing in disclosure policies and selfcontrol is negatively related to irrational behavior of investor.psychology theories, financial reporting, disclosure, investor, judgment, decision making process, psychology variables

Active labour market policies and job tenure

In this paper, we study the effect of subsidised on-the-job training, training for the unemployed and pure wage subsidies on the probability of leaving an employer. We base the analysis on a sample of unemployed workers who have been hired during the 1991-92 period. Since individuals benefiting from the policy were over represented in the sample, we face an endogenous sampling problem apart from the well known selectivity problem in evaluation analysis. The analysis deals with these two issues simultaneously. We find that each of the labour market policies increases the length of job tenure. Yet, in line with the literature (Lalonde 1986, Fraker and Maynard 1987), the magnitude and the significance of this effect depend crucially on the parametric assumptions in the model. Nevertheless, one robust conclusion is that subsidised on-the-job training schemes significantly decrease the incidence of job termination. We claim that this result supports Stevens' (1994, 1996) hypothesis of transferable training and consequently of the underprovision of training by the market. Training programs for the unemployed and pure wage subsidies only have an important positive but non significant effect on job tenure. We argue that the stated effect of training programs provides weak support for human capital theories as opposed to matching theories in the explanation of job turnover.

Imperfect competition in the labour market

It is increasingly recognized that labour markets are pervasively imperfectly competitive, that there are rents to the employment relationship for both worker and employer. This chapter considers why it is sensible to think of labour markets as imperfectly competitive, reviews estimates on the size of rents, theories of and evidence on the distribution of rents between worker and employer, and the areas of labour economics where a perspective derived from imperfect competition makes a substantial difference to thought

Affordability of complementary health insurance in France : a social experiment.

In order to improve financial access to complementary health insurance (CHI) in France, a CHI voucher program, called Aide Complémentaire Santé (ACS) was introduced in 2005. Four years later, the program covered only 18% of the eligible population. Two main hypotheses are put forward to account for this low take-up rate. The first one is related to the lack of information on the program itself and on its application process. While the second one considers that the amount of the financial support is too small to encourage people to purchase a CHI plan. We conduct a controlled experiment with the National Health Insurance Fund in order to assess these assumptions. A sample of eligible insurees living in an urban area in northern France were randomly split into three groups: a control group who received the standard level of financial aid, a group benefiting from a 75% voucher increase, and a third group benefiting from the same 75% voucher increase plus an invitation to an information meeting on ACS. After six months of follow-up, we observed how many application forms were sent back and how many of them entitled to ACS. Five main conclusions can be drawn from that analysis. (1) The voucher increase has a slight but statistically significant effect on ACS take-up. (2) It also allows better targeting of people actually eligible and thus reduces the number of ACS refusals due to resources above the upper limit. (3) However the invitation to the meeting seems unexpectedly to cancel the positive effect of the voucher increase when both treatments are applied jointly. (4) On the contrary, after controlling for potential selection bias, we observed that attending the briefing has a significant impact on ACS take-up. (5) This study confirms that ACS is complex and reaches poorly its target population. Only 17% of the insurees applied for ACS and only 9% of insures who were invited to the information briefing actually attended it. Moreover, previous CHI holders responded similarly to CHI non holders to treatments, which suggests that the central issue of ACS low take-up rate is not the CHI cost itself but most certainly the access to information, the burden and the complexity of the application process.France; Subsidized Health insurance; low-income population; uninsured; randomized experiment;