5,121 research outputs found
Contra Epstein, Good Explanations Predict
Epstein has argued that an explanation\'s capacity to make predictions should play a minor role in its evaluation . This view contradicts centuries of scientific practice and, at least, decades of philosophy of science. We argue that the view is not only unfounded but seems to arise from a mistaken fear that ABM models are in need of defense against the criticism that they don\'t necessarily forecast events in the natural or social world.ABM, Agent Based Model, Modeling, Prediction, Explanation, Philosophy of Science
The emergence of insect resistance in Bt-corn: implication of resistance management information under uncertainty
"The successful management of transgenic technology is likely to depend on the economic behavioral response of farmers to the regulated use of transgenic crops. A well-studied example is the widespread use of Bt-corn, in the United States, and elsewhere, to control the European Corn Borer, a major corn pest. The extensive use of Bt-corn has led to concerns about the emergence of insect resistance. The United States Environment Protection Agency addressed this potential problem by developing an insect resistance management strategy, based, in part, on complex mathematical models using detailed biological assumptions about the population genetics and life history of the European Corn Borer. However, seed companies and others have sometimes used simpler deterministic profit models to justify the economics of Bt-corn to potential growers. Therefore an over reliance, by regulatory agencies, on complex modeling approaches may obscure the likely economic behavioral response of farmers who rely on these less complex models. However, the determinants of adoption are numerous, profit being one of them. We develop a simple model for the spread of resistance based on the logistic growth equation and use it to investigate the effect of uncertainty on farmer decisions to plant Bt-corn and follow EPA management rules. The model results suggest that planting Bt-corn is an optimal strategy under the type of uncertainty assumed in the model and that short-term economic behavior is likely to lead to the Environment Protection Agency management rules not being followed. Our results add weight to existing work on this problem." Authors' AbstractBt-corn, logistic growth, Monte Carlo methods, Corn, Environmental protection, Economics Methodology,
Early Modern Masculinities in 1 and 2 Henry IV
Early modern ideals of masculinity were notably inconsistent, and often contradictory, yet remained prominently embedded within the ideology of Elizabethan England. This thesis focuses on how Shakespeare’s 1 and 2 Henry IV expose the dangerous consequences of these ideals when situated in competition with one another by reproducing them during a period of intense civil upheaval. These plays reveal the deficiencies of conventional models of masculinity, particularly through the characters of Falstaff and Percy, as well as the need for a new model of masculinity that can provide the state with order and stability. The resulting Machiavellian ideal, which Hal constructs from other competing ideals, is a model of masculinity that operates according to a principle of control, both in the political sense and over oneself. Percy’s death and Falstaff’s banishment signal the emergence of Hal’s Machiavellian ideal as a more effective model of masculinity, which flourishes not through prescribed notions of manhood but by actively negotiating the beneficial or destructive aspects of particular ideals, combining them in accordance with an ever-changing society. By tracing these changes, masculinity is revealed as a composite of many ideological registers that depend on ideas of, among others, bodies, language, and politics
Land Cover Change During a Transition in Land Management at Valles Caldera 1989-2013
This study examines how land-use policies can play a role in manifesting physical landscape changes. In 2000, Congress enacted a unique experiment in public lands management by creating the Valles Caldera National Preserve and its governing body, the Valles Caldera Trust (VCT). The management approach enacted by Valles Caldera Trust marked a significant departure in land-use intensity. To assess how these changes in management have affected land-use intensity and resulting cover change, this research seeks to identify landscape-level changes that taken place during a period of ten years prior to and following the formation of the Valles Caldera National Preserve (i.e., 1989-2013). Remote sensing techniques were used to quantify land cover transitions. Landsat image data (30m) from 1989, 1999, 2003, and 2013 were compared to identify changes that have taken place between the time periods 1989-1999, a period just prior to the purchase of the Baca Ranch by the federal government, and 10 years of management by the Valles Caldera Trust, 2003-2013. In order to do this, pre-classification change detection was used to quantify changes that have taken place during each period and a range of historical evidence used to classify those changes by disturbance regime. Results demonstrate an increase in wetland and rangeland recovery under VCT management based on evaluating several ancillary datasets. This leads to the conclusion that adaptive management strategies were beneficial for these cover types. The impact of the VCTs adaptive management strategies on forests is difficult to understand due to large wildfire-induced cover changes that occurred during VCT management.\u2
The Molecular Nature of Tumorigenesis
This paper is an exploration of the molecular aspects behind the tumor development process. Robert Weinberg provides an in-depth analysis of the subject matter over a series of publications entitled The Hallmarks of Cancer, The Hallmarks of Cancer: the next generation, and The Biology of Cancer. Current therapy development in the context of the hallmarks of cancer are discussed. The paper espouses some theories about the main differences between pediatric and adult cancers, specifically dealing with the mortality rates. The molecular aspects of tumorigenesis are discussed with particular attention to the tumor suppressor protein p53. This flows into the current treatment of cancer and how the future of cancer therapy development lies in novel concepts such as p53-induced apoptosis. Finally, some major methods of cancer prevention are presented because a reduction in the incidence of cancer, rather than improvements in current therapeutic techniques provide the best prospects for a reduction in cancer-associated mortality. Prevention is the cure.B.S
Critical Properties in the Assembly Call of the Common American Crow
According to tradition, the communication system of the American crow, Corvus brachyrhynchos, consists of an assortment of distinct sounds each of which is used in a particular context and has a unique meaning. Despite this traditional view, we have made field observations which suggested that the sounds employed in various different functional contexts overlap considerably. These observations further suggested that each sound does not have a single unique meaning, but that its meaning varies depending upon how it and similar sounds are temporally organized into calling sequences. In order to investigate this idea, a series of experiments were performed in which the temporal properties of natural sounds recorded from crows in the field were changed. These experiments were concerned primarily with the vocalization known as the assembly call. The assembly call consists of series of sounds which are low, harsh, and variable in pitch and timing. Broadcast to crows in the field, recorded assembly calls provoke an aggregation of crows to the sound source about twenty-five percent of the time. The recordings broadcasted were of two sorts: sequences made up by modifying the temporal properties of a natural assembly call and sequences of sounds derived from calls given in other functional contexts which were then rearranged to approximate the temporal properties of an assembly call. These calls were tested on wild crows in the field. A presentation of a call was counted successful if at least one crow approached the sound source on a direct line. Different calls were compared with respect to the proportion of successful presentations. The results show that not all types of crow sounds can be manufactured into effective assembly calls. A high pitched call, even when arranged to approximate the temporal properties of the assembly call does not assemble crows at rates approaching the rate of assembly to natural assembly calls. On the other hand, the results also show that a sound need not be derived from an assembly call in order to be arranged into an effective assembly call. A call recorded in another functional context, but which has a harsh, grainy quality will assemble crows as well as or better than an assembly call if it is presented in the proper temporal arrangement. In fact, the highest rates of success were provoked by a sequence of such sounds having a high rate of emission and organized into short cycles of increasing rate. Such a call is two to four times more effective than a natural assembly call. These results are inconsistent with the traditional view that each particular caw in the repertoire of a crow has a discrete stable meaning. An alternate hypothesis is suggested in which the meaning of a sequence of crow sounds is thought to depend not only on the properties of the caws but upon the temporal properties of the sequence as well
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