INFORMATION THEORETIC ALTERNATIVES TO TRADITIONAL SIMULTANEOUS EQUATIONS ESTIMATORS IN THE PRESENCE OF HETEROSKEDASTICITY

Finite sampling properties of information theoretic estimators of the simultaneous equations model, including maximum empirical likelihood, maximum empirical exponential likelihood, and maximum log Euclidean likelihood, are examined in the presence of selected forms of heteroskedasticity. Extensive Monte Carlo experiments are used to compare finite sample performance of Wald, Likelihood ratio, and Lagrangian multiplier tests constructed from information theoretic estimators to those from traditional generalized method of moments.Research Methods/ Statistical Methods,

TRUNCATED REGRESSION IN EMPIRICAL ESTIMATION

In this paper we illustrate the use of alternative truncated regression estimators for the general linear model. These include variations of maximum likelihood, Bayesian, and maximum entropy estimators in which the error distributions are doubly truncated. To evaluate the performance of the estimators (e.g., efficiency) for a range of sample sizes, Monte Carlo sampling experiments are performed. We then apply each estimator to a factor demand equation for wheat-by-class.doubly truncated samples, Bayesian regression, maximum entropy, wheat-by-class, Research Methods/ Statistical Methods,

Ocular complications of herpes zoster ophthalmicus

Fifty percent of patients with ophthalmic zoster develop ocular complications. These may be mild or severe, and can lead to loss of sight which, by timely and good management can be prevented in most cases. Unfortunately knowledge of the complications and their management is often poor making the design and interpretation of clinical trials difficult. 1356 cases of ophthalmic zoster were collected over fifteen years with at least 6 months follow up. Their details and complications were entered into a database. There is a generally held impression that patients developing zoster do so because of impaired immunity. Analysis of our findings showed that this was not so. The database results were analyzed to quantify the incidence of complications and their correlates. Two common corneal complications that are difficult to manage and lead to visual impairment were studied in detail including: Mucous plaque keratitis is defined as a distinct entity appearing at an early or late stage and occurred in forty seven cases. Poor management leads to visual impairment from neurotrophic ulceration, megaplaque keratitis and glaucoma. Lipid keratopathy induces diminished visual acuity and photophobia. It occurred in thirty six cases. Careful and prolonged treatment of chronic stromal keratitis with topical steroid will prevent this occurring, but when it does successful laser occlusion of corneal blood vessels halts the deposition of lipid and may actually disperse it or make the host cornea safer for keratoplasty. One hundred and seventy six patients were screened orthoptically and the incidence of extraocular muscle palsies assessed with regard to distribution and natural history. Possible pathogeneses are discussed. Overall recovery was good. Lastly iritis and iris atrophy were identified in five hundred and twenty patients and twenty three were investigated with anterior segment fluorescein angiography. This showed that they were associated with an ischaemic vasculitis

EMPIRICAL LIKELIHOOD ESTIMATORS OF THE LINEAR SIMULTANEOUS EQUATIONS MODEL

Information theoretic estimators are specified for a system of linear simultaneous equations, including maximum empirical likelihood, maximum empirical exponential likelihood, and maximum log Euclidean likelihood. Monte Carlo experiments are used to compare finite sample performance of these estimators to traditional generalized method of moments.Research Methods/ Statistical Methods,

A STRUCTURAL-EQUATION GME ESTIMATOR

A generalized maximum entropy estimator is developed for the linear simultaneous equations systems model. We provide results on large and small sample properties of the estimator. Empirical results illustrate efficiency advantages of the generalized maximum entropy estimator proposed in this study over traditional estimators (e.g., 2SLS and 3SLS).Research Methods/ Statistical Methods,

Currency spillovers and tri-polarity : a simultaneous model of the US dollar, German mark and Japanese yen

This paper presents a simultaneous model of exchange rates between the three major countries. In addition to incorporating long-run equilibria and short-run dynamics, the model is designed to capture complex interactions between currencies not normally considered in exchange rate models. These interactions are shown to be important via generalised impulse response analysis, and the model as a whole to be an economically and statistically superior forecasting tool over relatively short horizons

Assessing the Value of the OpenOrbiter Program\u27s Research Experience for Undergraduates

This article presents an assessment of the benefits gained by undergraduate students who participated in the OpenOrbiter Small Spacecraft Development Initiative. It provides an overview of the program and its learning objectives, as they apply to undergraduate students. It compares the learning impact between students who participated and those who assumed leadership roles. Qualitative assessment with regard to benefits is also discussed. The article extrapolates from these results to identify program elements that were particularly instrumental in delivering the positive benefits discussed. Finally, future work is discussed

G-code Modeling for 3D Printer Quality Assessment

The Department of Computer Science at the University of North Dakota (UND) has been evaluating optical/imaging methods for measuring the quality of 3D printed parts. In particular, we are interested in optical/imaging methods that can detect and measure such quality issues as layer shifting, layer separation and splitting, overheating, dimensional accuracy, and infill errors. This paper describes our work towards the analysis of infill errors as the quality of the infill does impact the structural integrity of the part being made. Externally, a part may look acceptable, but if the infill is faulty the part may be structurally unsound. Furthermore, once a part is finished printing it is usually not possible to see the infill. Therefore, monitoring of the infill must be done while the part is being printed

Enhancing Classroom Performance: A Technology Design To Support The Integration Of Collaborative Learning And Participative Teams

Integral components of today’s successful business models frequently include information technology, effective collaboration, and participative teamwork among employees. It is in the best interest of students for educators to provide classrooms that reflect a profitable practitioner’s environment. Students studying for careers in business should learn the advantages of teamwork and apply what they learn by participating as members of project teams as part of curriculum activities.  Organizations are incorporating collaborative hardware, software, and spaces at an unprecedented pace and rapid advancements in technology are continuously changing collaboration and teamwork strategies. To better prepare students to perform in this type of environment, the John L. Grove College of Business at Shippensburg University of Pennsylvania has recently designed and equipped classrooms to support intellectual teamwork activities. The intent of this paper is to share the details regarding the teaching/learning experiences of the faculty and students using the facilities, the physical design of the spaces, and the technology that was incorporated into the designated spaces. The discussion of lessons learned and recommendations for designing and implementing a “real learning for real life” classroom should be particularly useful to institutions planning or actively involved in designing technology-enhanced collaborative or teamwork activity facilities.

Physical Linkage of the Vibrio Cholerae Mannose-Sensitive Hemagglutinin Secretory and Structural Subunit Gene Loci: Identification of the Mshg Coding Sequence.

Vibrio cholerae O1 expresses a variety of cell surface factors which mediate bacterial adherence and colonization at the intestinal epithelium. The mannose-sensitive hemagglutinin (MSHA), a type IV pilus, is a potential attachment factor of the V. cholerae El Tor biotype. We describe a TnphoA mutant that is defective in its ability to hemagglutinate mouse erythrocytes. The TnphoA insertion maps to a recently identified genetic locus that encodes products that are predicted to be essential for assembly and export of the MSHA pilus. Insertional disruption at this locus in a mshA-phoA reporter strain provides evidence for a role of this locus in the latter stages of pilus assembly and/or export. These constructs have provided physical markers by which we have established close physical linkage of this secretion locus to a set of genes that includes the mshA structural gene. Sequence analysis of the intervening region between these two loci has revealed the presence of an open reading frame with homology to pilus biogenesis genes of several gram-negative bacteria. This genetic organization suggests an entire operon encoding the MSHA pilus and the components necessary for its assembly and secretion to the bacterial cell surface. The nomenclature of the MSHA structural and secretory locus has been redefined accordingly