Assessing electron heat flux dropouts as signatures of magnetic field line disconnection from the Sun

Suprathermal electrons focused along magnetic field lines, called the strahl, carry heat flux away from the Sun. Various factors can cause heat flux dropouts (HFDs), including times when the strahl almost vanishes. HFDs are a necessary but insufficient condition for detecting magnetic flux disconnected from the Sun. To quantitatively assess the fraction of HFDs which might be due to disconnected fields, we use four years of suprathermal electron data from the Wind spacecraft to perform a comprehensive survey of heat flux dropouts with durations greater than an hour. Eliminating periods within interplanetary coronal mass ejections or containing counterstreaming electrons, we find that only ∼10% of HFDs have signatures consistent with disconnected flux

MARGINAL AGRICULTURAL LAND CLASSIFICATION: A NEW APPROACH

Land Economics/Use,

Evaluating some computer enhancement algorithms that improve the visibility of cometary morphology

The observed morphology of cometary comae is determined by ejection circumstances and the interaction of the ejected material with the local environment. Anisotropic emission can provide useful information on such things as orientation of the nucleus, location of active areas on the nucleus, and the formation of ion structure near the nucleus. However, discrete coma features are usually diffuse, of low amplitude, and superimposed on a steep intensity gradient radial to the nucleus. To improve the visibility of these features, a variety of digital enhancement algorithms were employed with varying degrees of success. They usually produce some degree of spatial filtering, and are chosen to optimize visibility of certain detail. Since information in the image is altered, it is important to understand the effects of parameter selection and processing artifacts can have on subsequent interpretation. Using the criteria that the ideal algorithm must enhance low contrast features while not introducing misleading artifacts (or features that cannot be seen in the stretched, unprocessed image), the suitability of various algorithms that aid cometary studies were assessed. The strong and weak points of each are identified in the context of maintaining positional integrity of features at the expense of photometric information

A Simulation Estimator for Testing the Time Homogeneity of Credit Rating Transition

The measurement of credit quality is at the heart of the models designed to assess the reserves and capital needed to support the risks of both individual credits and portfolios of credit instruments. A popular specification for credit- rating transitions is the simple, time-homogeneous Markov model. While the Markov specification cannot really describe processes in the long run, it may be useful for adequately describing short-run changes in portfolio risk. In this specification, the entire stochastic process can be characterized in terms of estimated transition probabilities. However, the simple homogeneous Markovian transition framework is restrictive. We propose a test of the null hypotheses of time-homogeneity that can be performed on the sorts of data often reported. We apply the tests to 4 data sets, on commercial paper, sovereign debt, municipal bonds and S&P Corporates. The results indicate that commercial paper looks Markovian on a 30-day time scale for up to 6 months; sovereign debt also looks Markovian (perhaps due to a small sample size); municipals are well-modeled by the Markov specification for up to 5 years, but could probably benefit from frequent updating of the estimated transition matrix or from more sophisticated modeling, and S&P Corporate ratings are approximately Markov over 3 transitions but not 4.

How can the concepts of habitus and field help us to understand the engagement of educational workers in higher Education?

In ‘Making a European area of lifelong learning a reality’, the EU stressed the role of universities in relation to lifelong learning, a role that entails a need for widening access to universities, particularly for those not coming through the traditional direct route of upper secondary education. As teachers play a significant role in the quality of the lifelong learning as well as in motivating future generations to take part in lifelong learning, education and training for teachers becomes important; not only in relation to initial teacher education, but also in relation to a continuous development of knowledge and skills. This paper represents the first stage of a larger comparative project intended to examine and compare educational workers’ (i.e. professionals involved in teaching in the class room) participation in higher education in England and Denmark, their access and interest. In particular, the paper relates participation and engagement to national and international educational policies and frames this work within an examination of the social background of the professional groups. The key research questions at this stage of the work are methodological and can be summed up by the overarching question, “How can the concepts of habitus and field help us to understand levels of engagement of educational workers in Higher Education”? The paper reports the results of our review of current policies and our efforts to identify the structural relations within the educational professional fields in each country. To do so we are developing a theoretical model using the relational analytical approach advocated by Bourdieu. As such, our work is an early stage attempt at operationalising Bourdieu’s observations regarding the dynamics of field. This seems to us to provide an important conceptual approach to understanding the habitus of educational workers in the context of the dynamics of a fast changing policy arena and the complexities of the backgrounds of individuals working in the educational field. The model attempts to build in the reflexivity that Bourdieu demands for a ‘science’ that is not weakened by over-emphasis on either the objective structural relations or the subjective phenomenology of experience. Thus, the paper presents a preliminary contextual analysis of the factors that enable an understanding of engagement or lack of engagement in higher level learning among school-based education workers in the two EU countries and is related to a larger research project that explores habitus (both individual and collective) among these groups of education workers

Specification and Informational Issues in Credit Scoring

Lenders use rating and scoring models to rank credit applicants on their expected performance. The models and approaches are numerous. We explore the possibility that estimates generated by models developed with data drawn solely from extended loans are less valuable than they should be because of selectivity bias. We investigate the value of "reject inference"--methods that use a rejected applicant's characteristics, rather than loan performance data, in scoring model development. In the course of making this investigation, we also discuss the advantages of using parametric as well as nonparametric modeling. These issues are discussed and illustrated in the context of a simple stylized model.

CO2 laser waveguiding in proton implanted GaAs

Surface layers capable of supporting optical modes at 10.6 microns have been produced in n-type GaAs wafers through 300 keV proton implantation. The dominant mechanism for this effect appears to be free carrier compensation. Characterization of the implanted layers by analysis of infrared reflectivity spectra and synchronous coupling at 10.6 microns produced results in good agreement with elementary models. These results of sample characterization by infrared reflectivity and by CO2 laser waveguiding as implanted are presented and evaluated