39,607 research outputs found

    The Substitutability of Equities and Consumer Durable Goods: A Portfolio-Choice Approach

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    Using the analytical approach made famous by Chetty [4] and quarterly data covering the period from 1963.4 through 1991.3, we estimate elasticities of substitution between common stocks and residential housing and between stocks and government bonds, Treasury bills, money, the sum of savings and time deposits, and corporatep aper.3W e also test whethert hese elasticities changed following the 1987 stock market crash. We find that there is virtually no substitutabilityb etween stocks and other financial assets. Moreover, we find no evidence that asset holders are willing to substitute between stocks and housing. This last finding contradicts Runkle\u27s suggestion that as stock returns decline, consumers may move into housing, or other durable goods. In fact, it appears that individuals consider equities to be a requirement in their portfolio, and are not willing to use other assets as substitutes. We also find that, with one exception, the stock market crash of 1987 did not have a significant impact on the substitutabilityb etween common stocks and the othera ssets. The only exception is that, following the crash, stocks and Treasury bills actually became complements

    Bayesian variants of some classical semiparametric regression techniques

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    This paper develops new Bayesian methods for semiparametric inference in the partial linear Normal regression model: y=zβ+f(x)+var epsilon where f(.) is an unknown function. These methods draw solely on the Normal linear regression model with natural conjugate prior. Hence, posterior results are available which do not suffer from some problems which plague the existing literature such as computational complexity. Methods for testing parametric regression models against semiparametric alternatives are developed. We discuss how these methods can, at some cost in terms of computational complexity, be extended to other models (e.g. qualitative choice models or those involving censoring or truncation) and provide precise details for a semiparametric probit model. We show how the assumption of Normal errors can easily be relaxed

    The Brutal Murder of George J. Bushman

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    In the fall of 1918 there occurred in Adams County a singularly brutal murder that brought the County and the town of Gettysburg to a shocked standstill. The tentacles of this event would reach into four Pennsylvania counties: Adams, Cumberland, Dauphin, and Philadelphia, and eventually the Pennsylvania Supreme Court. The investigation of the crime and the trial of the perpetrators involved so many public officials and families, as well as the extended judicial system and geographical locations within and without the County, that we have included a Cast of Characters and Locations to assist the reader in following this convoluted tale

    Diversity and Dynamics of Indigenous \u3cem\u3eRhizobium japonicum\u3c/em\u3e Populations

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    A simple method, based upon the separation of cellular proteins by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, has been devised for distinguishing between isolates of Rhizobium japonicum. Eleven laboratory strains, previously classified into five serogroups, were analyzed by gel electrophoresis. Groups determined subjectively according to protein patterns matched the serogroups, with one exception. Most strains within serogroups could be distinguished from one another. For studying the ecology of Rhizobium, an important advantage of this technique compared with serology or phage typing is that it discriminates among previously unencountered indigenous bacterial isolates as well as among known laboratory strains. SDS-gels were used to analyze the Rhizobium population of 500 nodules, sampled throughout the growing season, from soybeans at two different Wisconsin localities. Although the soybeans had been inoculated with laboratory strains of R. japonicum, indigenous R. japonicum predominated. At one location, 19 indigenous gel types were distinguished and classified mainly into four groups. At the other location, 18 gel types, falling mainly into three groups, were detected. The predominance of a particular group varied, in some cases dramatically, depending upon the time and depth of nodule formation

    Organic farming and gene transfer from genetically modified crops

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    This is the final report of MAFF/Defra project OF0157. Genetically modified (GM) crops cannot be released into the environment and used as food, feed, medicines or industrial processing before they have passed through a rigorous and internationally recognised regulatory process designed to protect human and animal health, and the environment. The UK body that oversees standards in organic farming, the United Kingdom Register of Organic Food Standards (UKROFS), has ruled that genetically modified (GM) crops have no role to play in organic farming systems. They, therefore, have concerns about the possibility and consequences of the mixing of GM crops with organic crops. The two main sources of mixing are through pollen and seed. Pollen from GM crops may pollinate an organic crop. Seed from a GM crop, or plants established from them, may become mixed with organic crops or their products. Minimising genetic mixing is an important feature of the production of all high quality seed samples of plant varieties supplied to farmers. Extensive experience has been obtained over many decades in the production of high purity seed samples. Crop isolation distances, and crop rotational and management practices are laid down to achieve this. These procedures for the production of seed of high genetic purity could be used for the production of organic crops. No system for the field production of seed can guarantee absolute genetic purity of seed samples. Very rarely long distance pollination or seed transfer is possible, so any criteria for organic crop production will need to recognise this. There has always been the possibility of hybridisation and seed mixing between organic crops and non-organic crops. Organic farming systems acknowledge the possibility of spray or fertiliser drift from non-organic farming systems, and procedures are established to minimise this. In practice, detecting the presence of certain types of GM material in organic crops, especially quantification, is likely to be difficult. Some seed used by organic farmers are currently obtained from abroad. After January 2001, or a modified deadline thereafter, UK organic farmers will be required to sow seed produced organically. There is little or no organic seed produced in the UK at present, so it has to be obtained from abroad. Seed obtained from outside the UK or the European Union, may have different seed production criteria. This may make it difficult to guarantee that it is absolutely free from any GM material. Organic farmers and/or GM crop producers will need to ensure that their crops are isolated from one another by an appropriate distance or barrier to reduce pollen transfer if the crop flowers. To reduce seed mixing, shared equipment will need to be cleaned and an appropriate period of time allowed before organic crops are grown on land previously used for GM crops. Responsibility for isolation will need to be decided before appropriate measures can be implemented. The report highlights the need for acceptable levels of the presence of GM material in organic crops and measures identified to achieve this

    A Pilot Evaluation Study Using LectureTools to Enhance Interactivity in Classroom-Based Teaching in a Project Management Course

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    With students’ ownership of laptops and mobile devices increasing, there exists an opportunity to harness their use to support interactivity within the traditional classroom. Two educators, motivated to enhance interactivity in a two-day project management course at a UK university, trialled LectureTools, a cloud-based audience-response system. To assess potential benefits to learning and teaching, as well as identifying accompanying challenges, an evaluation study was carried out comprising a range of data sources. These included observation of a LectureTools-based lecture and a student questionnaire followed by a focus group discussion with a subset of students about their experiences throughout the two days. Interviews with both teachers were also conducted, adding to the evaluation research data and giving them an opportunity to reflect on their teaching practice. All participants recognised the benefits of LectureTools in promoting student engagement, learning and discussion while students acknowledged the distractive potential of having laptops in the lecture theatre. Efforts are required by educators to ensure that the interactive potential of laptops in classrooms to enhance learning and teaching is supported while controlling the potential for distraction. Future research is needed to ascertain the impact of using LectureTools on approaches to learning and teaching

    Dynamic and Structural Features of Intifada Violence: A Markov Process Approach

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    This paper analyzes the daily incidence of violence during the Second Intifada. We compare several alternative statistical models with different dynamic and structural stability characteristics while keeping modelling complexity to a minimum by only maintaining the assumption that the process under consideration is at most a second order discrete Markov process. For the pooled data, the best model is one with asymmetric dynamics, where one Israeli and two Palestinian lags determine the conditional probability of violence. However, when we allow for structural change, the evidence strongly favors the hypothesis of structural instability across political regime sub-periods, within which dynamics are generally weak.Bayesian; Conjugate prior; Israeli-Palestinian conflict; Marginal likelihood
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