Improved liquid-level sensor for cryogenics

Liquid-level indicator, consisting of a diode heated by a resistor, allows simultaneous use of two or three of the liquids nitrogen, hydrogen, and helium. Operation depends on strong temperature-dependence of the forward resistance of a germanium diode and the difference between liquid and vapor in heat-transfer properties

"Securitization"

"At the annual banking structure and competition conference of the Federal Reserve Bank of Chicago in May 1987, the buzzword heard in the corridors and used by many of the speakers was 'that which can be securitized, will be securitized.'" So notes Hyman Minsky in a prescient memo on the nature, and the implications, of securitization, written 20 years before an explosion in the securitization of home mortgages helped create the current financial crisis. This memo, which served as the basis for a lecture in Minsky's monetary theory class at Washington University, has not been widely circulated. It is published here in its entirety, with a preface and an afterword by Senior Scholar L. Randall Wray that places Minsky's work in context.

Procedures and requirements for testing in the Langley Research Center unitary plan wind tunnel

Information is presented to assist those interested in conducting wind-tunnel testing within the Langley Unitary Plan Wind Tunnel. Procedures, requirements, forms and examples necessary for tunnel entry are included

Factors Preventing Male Teachers From Seeking Employment at the Elementary Level

The purpose of this qualitative study was to explore the perceptions of male middle school educators regarding the prospects of teaching at the elementary level. A semi-structured interview approach was employed in an effort to assess the factors that lead 12 male educators into middle level teaching positions. Subjects were recruited from diverse public school districts in northern New Jersey and each held elementary and middle school certification. The interview instrument for this study was based on both existing literature surrounding the absence of males in the elementary teaching ranks as well as Brown’s (2002) value-based theory of occupational choice and satisfaction. The latter served as the conceptual framework around which this study was designed. Four themes emerged from this research. The theme, nature of manhood, describes the often-cited differences perceived between men and women and how those differences impact subjects’ perceptions of the teaching profession. The theme, nature of students, reflects perceived variation between elementary-age students and the middle school-age pupils currently under the tutelage of the subject pool. The theme, nature of work, refers to the idea that elementary and middle school teaching positions each require unique energies and dissimilar pedagogical skills. Finally, the theme, stigma, speaks to the perceived impact that teaching younger students either could or would have on the reputation of a male in the role of elementary school teacher. This research has implications in the areas of teacher training and teacher recruitment. The findings offer a rare glimpse at the perceptions of an educational minority—male elementary teachers

Factors Preventing Male Teachers From Seeking Employment at the Elementary Level

The purpose of this qualitative study was to explore the perceptions of male middle school educators regarding the prospects of teaching at the elementary level. A semi-structured interview approach was employed in an effort to assess the factors that lead 12 male educators into middle level teaching positions. Subjects were recruited from diverse public school districts in northern New Jersey and each held elementary and middle school certification. The interview instrument for this study was based on both existing literature surrounding the absence of males in the elementary teaching ranks as well as Brown’s (2002) value-based theory of occupational choice and satisfaction. The latter served as the conceptual framework around which this study was designed. Four themes emerged from this research. The theme, nature of manhood, describes the often-cited differences perceived between men and women and how those differences impact subjects’ perceptions of the teaching profession. The theme, nature of students, reflects perceived variation between elementary-age students and the middle school-age pupils currently under the tutelage of the subject pool. The theme, nature of work, refers to the idea that elementary and middle school teaching positions each require unique energies and dissimilar pedagogical skills. Finally, the theme, stigma, speaks to the perceived impact that teaching younger students either could or would have on the reputation of a male in the role of elementary school teacher. This research has implications in the areas of teacher training and teacher recruitment. The findings offer a rare glimpse at the perceptions of an educational minority—male elementary teachers

Stock market indicators: Can they forecast the future movements in stock prices?

Thesis (M.B.A.)--Boston Universit

Advances in travel geometry and urban modelling

Urban travel geometry is a generalization of patterns of movement in cities and regions where route configuration and prevailing traffic speeds constrain or direct movement in distinctive and repeatable patterns. In this paper we use these properties to construct time surfaces on which distance equates to the time of travel in the urban plane. Such surfaces can be two- or three-dimensional and are useful in the study of urban structure, locational analysis, transport planning and traffic management. A particular niche addressed in this paper is non-conformal time surface transformations in which speed or the cost of travel is constrained according to co-ordinate directions. It is argued that such models may be more suited to gridded and orbital-radial cities than previously used conformal transformations. After explaining the rationale behind the approach, a mathematical basis is developed and several calibrated examples are provided based on regions in the UK. The paper concludes with some examples of potential applications, and an annex provides a detailed mathematical framework

Toll optimisation on river crossings serving large cities

There is renewed interest in the private sector financing and operation of major transportation projects, in which a significant financial contribution comes from toll revenues. Tolling is ideally suited to river crossings, where the tolls are relatively easy to administer and collect. Because of their span, bridges over river estuaries are particularly expensive to build and maintain and so need to be put on a firm financial footing. Toll revenue is therefore a key consideration if such projects are to be financially viable and risk is to be minimised. There may be other issues to do with who benefits from the bridge and whether differential tolls should apply to local residents and non-resident bridge users. In addition, such bridges may be linked to wider economic objectives, such as local development and regeneration. This paper describes a model for estimating optimum bridge tolls, from both a financial and a welfare perspective and provides a case study that illustrates a range of scenarios that are of general interest

Market area analysis under orbital-radial routing with applications to the study of airport location

The study of market areas provides one indication of the economic and strategic value of a facility or attraction and is a commonly used tool in geographical and economic analysis. In this paper, we study a class of models for use in stereotypical urban regions with an associated orbital–radial network. The aim of the paper is to provide the theoretical and analytical tools needed to understand the shapes, size and markets of an attraction as a function of both its location and the speeds of radial and orbital access to competing attractions. As a result, we need to identify several hitherto unrecognised constructs such as eclipsing in which, due to proximity to a fast orbital road, one attraction can eliminate the market of another. We outline a facility location methodology in a case study, based on London, concerning access to airports serving the metropolis. Among other things, we identify inner and outer eclipsing envelopes for a new airports, which substantially narrows the area of search for an optimum location