Your search
Results 61 resources
-
Background. The objective of this study was to identify factors that categorize patients with epithelial ovarian carcinoma into favorable and unfavorable prognostic groups at the time of initial treatment. Methods. Data were analyzed from 51 women who were treated at Yale University, had an evaluable CA 125 half-life (t 0.5), and were followed for disease recurrence for at least 2 years. Results. Grade, maximum level of CA 125, and histology did not provide useful prognostic information. Stage, residual disease, minimum CA 125, and CA 125 t 0.5 individually were predictive of persistent disease or recurrence within 3 years of diagnosis with sensitivities of 97, 70, 34, and 49%, respectively, and specificities of 33, 83, 100, and 83%, respectively. When these factors are combined, defining an unfavorable prognostic group as those patients having residual disease greater than 1 cm, CA 125 t 0.5 greater than 12 days, or minimum CA 125 never falling below 35 U/ml, sensitivity and specificity were 96 and 65%, respectively, at 1 year of follow-up and 91 and 75%, respectively, at 3 years of follow-up. Conclusions. In those patients in whom residual small volume disease after primary surgery indicates a good prognosis, minimum CA 125 and CA 125 t 0.5 during chemotherapy can further categorize patients into favorable and unfavorable prognostic groups.
-
Three types of tags, external, internal, and sonic, have been used to study migration of the American lobster Homarus americanus. Tag loss and interpretation of returned tag data are serious problems associated with internal and external tags. Lobster tracking using sonic tags is still in the pilot stage. Lobster migration is redefined to include horizontal and vertical displacements. Depth of displacement is a more reasonable measurement of lobster migration than horizontal distance traveled. Two distinct lobster populations are discernable based on their ecological habitation and migratory behavior. Evidence in this review suggests that the deep-sea lobster migrates, whereas the coastal lobster may move within a limited range. © 1994, Taylor & Francis Group, LLC. All rights reserved.
-
Ordinary least squares (OLS) regression is relatively sensitive to the presence of outliers in a data set. In this paper, a robust estimation method, least median of squares (LMS) is used to identify outliers in land value data. Once the outliers are identified, are the land value equations re-estimated. The results show that a few observations can have a significant effect on the estimated coefficients. Finally, the observations which were identified as outliers were examined in more detail. One cause of outliers is an omitted variable. In this case, a large fraction of the outliers were found to be observations with high development potential.
-
This paper examines the effect of a zoning change on the land market in McHenry County, Illinois. One question addressed is whether zoning `'follows the market.” It is found that, for agricultural land, zoning does tend to follow the market. In addition, the effect of land prices on land use is examined. The results here, however, are mixed. In the initial years after the zoning change, a high relative price of residential land increases the probability that a parcel will be zoned residential. However, several years later, a high relative price of residential land decreases the probability that a parcel is zoned residential. This result suggests that it may take some time for a zoning change to have a significant impact on the local land market.
-
After surveying the evolution of the major methodologies in inflation hedging, this study presents a unique methodology that uses principal component factor analysis to separate the effects of variability in the real rate of return from the nominal rate of return. This approach allows the effects of both anticipated and unanticipated inflation on rates of return to be estimated more precisely. This study finds that art objects perform well in terms of average real rates of return and that the market, though not perfect, integrates anticipated inflation into the rates of return. However, unanticipated inflation is very often negatively related to the rates of return. Copyright © 1994, Wiley Blackwell. All rights reserved
-
Over the past several years we have been interested in the supervised classification of ultrasonic images of the liver based on quantitative texture features. Our most recent efforts are concerned with the inclusion of features computed from Markov random fields. After adding four such features to our existing model containing 17 features, we employed stepwise discriminant analysis to identify the features that could best discriminate among 184 previously classified normal and abnormal ultrasonic images. Three of the four features derived from Markov random field models were identified by stepwise discriminant analysis as being good discrimination along with 6 existing features. From these results we constructed a backpropagation neural network with an input layer consisting of 9 nodes. We found that this new model yielded slightly better results when compared to earlier models. Our most recent results yielded a sensitivity of 81%, a specificity of 77% and an overall accuracy of 79%.
-
Constraint-based spatial reasoning problems frequently arise in the area of military mission planning. In this domain, mission planners employ complex criteria, which may include numeric and optimization constraints in addition to logical constraints and rules, to develop engineering construction and resource deployment plans. Automated planning aid systems for the military must have the capability to represent the various types of constraints used in human decision-making and must be able to provide efficient and optimal or near optimal solutions to the resulting constraint satisfaction problems. This paper describes a methodology for transforming constraint satisfaction problems into nonlinear optimization problems and for solving the resulting optimization problems using a hybrid neural network/genetic algorithm procedure. The method is applied to illustrative problems which employ different types of constraints for determination of future construction sites. The results of the experiments demonstrate the potential of this methodology for finding feasible and optimal solutions to nonlinear optimization problems. © 1994, Elsevier B.V.
Explore
Resource type
- Book (17)
- Conference Paper (2)
- Journal Article (34)
- Report (8)
Publication year
Resource language
- English (47)