A method for comparing non-nested models with application to astrophysical searches for new physics

Searches for unknown physics and decisions between competing astrophysical models to explain data both rely on statistical hypothesis testing. The usual approach in searches for new physical phenomena is based on the statistical Likelihood Ratio Test (LRT) and its asymptotic properties. In the common situation, when neither of the two models under comparison is a special case of the other i.e., when the hypotheses are non-nested, this test is not applicable. In astrophysics, this problem occurs when two models that reside in different parameter spaces are to be compared. An important example is the recently reported excess emission in astrophysical $\gamma$-rays and the question whether its origin is known astrophysics or dark matter. We develop and study a new, simple, generally applicable, frequentist method and validate its statistical properties using a suite of simulations studies. We exemplify it on realistic simulated data of the Fermi-LAT $\gamma$-ray satellite, where non-nested hypotheses testing appears in the search for particle dark matter.Comment: We welcome examples of non-nested models testing problem

Evaluating the influence of lake morphology, trophic status and diagenesis on geochemical profiles in lake sediments

Recent geochemical studies provide evidence that changes in vertical distributions of nutrients in lake sediments are driven by anthropogenic activities, based primarily on trends of increasing concentrations in upper sediment layers. However, we show that vertical concentration profiles of carbon (C), nitrogen (N) and phosphorus (P) in lake sediments can be higher in the upper, most recently deposited sediment strata, driven largely by natural diagenetic processes and not eutrophication alone. We examined sediment cores from 14 different lakes in New Zealand and China ranging from oligotrophic to highly eutrophic and shallow to deep, and found that the shape of vertical profiles of total P, a key nutrient for lake productivity, can be similar in sediments across gradients of widely differing trophic status. We derived and applied empirical and mechanistic diagenesis steady state profile models to describe the vertical distribution of C, N and P in the sediments. These models, which focus on large scale temporal (decades) and spatial (up to 35 cm in the vertical) processes, revealed that density-differentiated burial and biodiffusive mixing, were strongly correlated with vertical concentration gradients of sediment C, N and P content, whereas lake trophic status was not. A sensitivity analysis of parameters included in the diagenetic model further showed that the processes including flux of organic matter to the sediment-water interface, burial (net sedimentation), breakdown of organic matter and biodiffusion all significantly can influence the vertical distribution of sediment P content. We conclude that geochemical studies attempting to evaluate drivers of the vertical distribution of sediment C, N, and P content in lake sediments should also account for the natural diagenetic drivers of vertical concentration gradients, assisted with application of similar models to those presented in this study. This would include quantification of key sediment diagenesis model parameters to separate out the influence of anthropogenic activities

Temporal and spatial variations in phytoplankton productivity in surface waters of a warm-temperate, monomictic lake in New Zealand

Surface phytoplankton productivity measurements were carried out in morphologically complex Lake Rotoiti with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. Measurements were carried out monthly at two depths at each of three morphologically diverse stations for 1 year throughout the lake. Productivity at the surface of the shallow embayment was significantly higher in most months of the year compared with the surface of the other two stations but there were no significant differences from September to December 2004. There were no relationships between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between sites found in this study indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole lake productivity estimates may vary greatly depending on the location and depth of productivity measurements

"The greatest good for the greatest number" : American land redistribution in East and Southeast Asia, 1945-1969

Between 1945 and 1969, United States policymakers advocated the redistribution of farmland in East and Southeast Asian countries including Japan, South Korea, Taiwan, and South Vietnam. Land reformers hoped to prevent communist insurgencies in rural Asia and promote economic growth, but land redistribution was not merely a means to an end. Mid-century American policymakers viewed the equalization of landownership as an end unto itself because of their shared Jeffersonian ideology. Despite a consistent worldview and a largely consistent methodology, reformers faced different challenges and achieved varying degrees of success in the countries they hoped to reform. The example of the Philippines, while arguably more Latin American than Asian with respect to landownership patterns, serves as a prologue to the American land reform experience in Asia. The postwar reforms begin with the well-known example of Japan, which set the standard for subsequent reforms both in terms of policy specifics and outcomes. The nearly-contemporary example of South Korea provides a unique twist since the United States itself was the peninsula’s largest landowner at the time of the reform. The American contributions to Taiwan’s post-1949 reform are recovered in chapter 4, while chapter 5 delves into bureaucratic infighting in Washington as a prelude to the final, troubled episode of South Vietnam.Histor

On methods for correcting for the look-elsewhere effect in searches for new physics

The search for new significant peaks over a energy spectrum often involves a statistical multiple hypothesis testing problem. Separate tests of hypothesis are conducted at different locations producing an ensemble of local p-values, the smallest of which is reported as evidence for the new resonance. Unfortunately, controlling the false detection rate (type I error rate) of such procedures may lead to excessively stringent acceptance criteria. In the recent physics literature, two promising statistical tools have been proposed to overcome these limitations. In 2005, a method to "find needles in haystacks" was introduced by Pilla et al. [1], and a second method was later proposed by Gross and Vitells [2] in the context of the "look elsewhere effect" and trial factors. We show that, for relatively small sample sizes, the former leads to an artificial inflation of statistical power that stems from an increase in the false detection rate, whereas the two methods exhibit similar performance for large sample sizes. We apply the methods to realistic simulations of the Fermi Large Area Telescope data, in particular the search for dark matter annihilation lines. Further, we discuss the counter-intutive scenario where the look-elsewhere corrections are more conservative than much more computationally efficient corrections for multiple hypothesis testing. Finally, we provide general guidelines for navigating the tradeoffs between statistical and computational efficiency when selecting a statistical procedure for signal detection

When the Emperor was Divine by Julie Ostuka (2003) & The Buddha in the Attic by Julie Ostuka (2012)

Histor

The speaker in the major poems of William Cowper

Includes vita."The fate of William Cowper as poet may very well turn out to be analogous to what threatened to be the fate of Samuel Johnson: the history of the man will become more important than his literary achievement. Of course the history of a man is the legitimate concern of biographers and all others primarily interested in biography, but when the literary critic, whose business should be to discuss literature, shifts his emphasis away from the work to the man behind it, he is no longer writing as a literary critic. What amounts to an indictment of Cowper as a poet is most obviously expressed by Gilbert Thomas: "All attempts to estimate his poetry merely as poetry, are futile; we cannot dissociate the poetry from the man" and Walter Bagehot: "Only a most pedantic critic would attempt to separate the criticism on Cowper's works from a narrative of his life. Indeed, such an attempt would be scarcely intelligible." The implication here is clear-- the poetry is not really worth discussing as being interesting in itself. These views are extreme, but they are not isolated examples. In one modified form or another they run through nearly all of the major critical studies of Cowper. For example, Norman Nicholson, a critic who has the most to say about Cowper's poetry, feels that since his poetry never "transcends the personality of the poet," part of our attention is always on the poet rather than on the poem: "to those who love Cowper, his poetry is a biography." Lord David Cecil, writing in an area somewhere between biography and criticism ("My purpose is . . . to tell straight-forwardly the story of this extraordinary man" ), finds that Cowper's poems are "not so good as the letters," which is another way of saying that the man is more interesting than his poetry."--Introduction.Includes bibliographical references

Data-Driven Process Discovery: A Discrete Time Algebra for Relational Signal Analysis

This research presents an autonomous and computationally tractable method for scientific process analysis, combining an iterative algorithmic search and a recognition technique to discover multivariate linear and non-linear relations within experimental data series. These resultant data-driven relations provide researchers with a potentially real-time insight into experimental process phenomena and behavior. This method enables the efficient search of a potentially infinite space of relations within large data series to identify relations that accurately represent process phenomena. Proposed is a time series transformation that encodes and compresses real-valued data into a well-defined, discrete-space of 13 primitive elements where comparative evaluation between variables is both plausible and heuristically efficient. Additionally, this research develops and demonstrates binary discrete-space operations which accurately parallel their numeric-space equivalents. These operations extend the method\u27s utility into trivariate relational analysis, and experimental evidence is offered supporting the existence of traceable multivariate signatures of incremental order within the discrete-space that can be exploited for higher dimensional analysis by means of an iterative best-n first search