The Overlooked Potential of Generalized Linear Models in Astronomy - I: Binomial Regression

Revealing hidden patterns in astronomical data is often the path to fundamental scientific breakthroughs; meanwhile the complexity of scientific inquiry increases as more subtle relationships are sought. Contemporary data analysis problems often elude the capabilities of classical statistical techniques, suggesting the use of cutting edge statistical methods. In this light, astronomers have overlooked a whole family of statistical techniques for exploratory data analysis and robust regression, the so-called Generalized Linear Models (GLMs). In this paper -- the first in a series aimed at illustrating the power of these methods in astronomical applications -- we elucidate the potential of a particular class of GLMs for handling binary/binomial data, the so-called logit and probit regression techniques, from both a maximum likelihood and a Bayesian perspective. As a case in point, we present the use of these GLMs to explore the conditions of star formation activity and metal enrichment in primordial minihaloes from cosmological hydro-simulations including detailed chemistry, gas physics, and stellar feedback. We predict that for a dark mini-halo with metallicity $\approx 1.3 \times 10^{-4} Z_{\bigodot}$, an increase of $1.2 \times 10^{-2}$ in the gas molecular fraction, increases the probability of star formation occurrence by a factor of 75%. Finally, we highlight the use of receiver operating characteristic curves as a diagnostic for binary classifiers, and ultimately we use these to demonstrate the competitive predictive performance of GLMs against the popular technique of artificial neural networks.Comment: 20 pages, 10 figures, 3 tables, accepted for publication in Astronomy and Computin

Directed mutagenesis as a technique to study protein function: application to β-lactamase

The function of a protein follows uniquely from its three-dimensional structure, which is unambiguously determined by the linear sequence of amino acids. Thus to undertake a systematic study of the relationship between protein structure and function, one would ideally like to be able to alter the structural gene in various ways to encode proteins with novel sequences, structures and functions. Various mutagenic strategies and methods have recently been developed that allow one to achieve these objectives

The String Calculation of QCD Wilson Loops on Arbitrary Surfaces

Compact string expressions are found for non-intersecting Wilson loops in SU(N) Yang-Mills theory on any surface (orientable or nonorientable) as a weighted sum over covers of the surface. All terms from the coupled chiral sectors of the 1/N expansion of the Wilson loop expectation values are included.Comment: 10 pages, LaTeX, no figure

The Overlooked Potential of Generalized Linear Models in Astronomy-III: Bayesian Negative Binomial Regression and Globular Cluster Populations

In this paper, the third in a series illustrating the power of generalized linear models (GLMs) for the astronomical community, we elucidate the potential of the class of GLMs which handles count data. The size of a galaxy's globular cluster population $N_{\rm GC}$ is a prolonged puzzle in the astronomical literature. It falls in the category of count data analysis, yet it is usually modelled as if it were a continuous response variable. We have developed a Bayesian negative binomial regression model to study the connection between $N_{\rm GC}$ and the following galaxy properties: central black hole mass, dynamical bulge mass, bulge velocity dispersion, and absolute visual magnitude. The methodology introduced herein naturally accounts for heteroscedasticity, intrinsic scatter, errors in measurements in both axes (either discrete or continuous), and allows modelling the population of globular clusters on their natural scale as a non-negative integer variable. Prediction intervals of 99% around the trend for expected $N_{\rm GC}$comfortably envelope the data, notably including the Milky Way, which has hitherto been considered a problematic outlier. Finally, we demonstrate how random intercept models can incorporate information of each particular galaxy morphological type. Bayesian variable selection methodology allows for automatically identifying galaxy types with different productions of GCs, suggesting that on average S0 galaxies have a GC population 35% smaller than other types with similar brightness.Comment: 14 pages, 12 figures. Accepted for publication in MNRA

Setting the seen: Whiteness as unmarked category in psychologists' writings on race in Australia

Damien W. Riggs, Jane M. Selb

Final Cultural Resources Report of the Salt Creek Midstream, LLC Proposed Olifant Eight Inch Pipeline Project on University Lands in Ward County, Texas

Enercon Services, Inc. (ENERCON), in support of Salt Creek Midstream, LLC, conducted an intensive archeological survey for the proposed Olifant Eight Inch Pipeline Project located near Pyote in Ward County, Texas. The proposed project consists of the construction of an approximately 800 foot (244 m) long eight inch steel pipeline on University Lands, extending from a tie-in at an existing well pad, trending generally south-southeast to a tie-in on the existing Quito Draw pipeline. The Olifant Eight Inch Pipeline Project area is mapped on the United States Geological Survey (USGS) Soda Lake NE, Texas (1967, photorevised 1981) 7.5 Minute Quadrangle map. The construction corridor consists of a 50 foot (15 m) wide permanent pipeline right-of-way (ROW) and a 50 foot (15 m) wide temporary workspace corridor. The cultural resources survey corridor and the area of potential effect (APE) was 100 feet (30 m) wide for the entire 800 foot (244 m) length of the proposed Olifant Eight Inch Pipeline Project, totaling 1.84 acres (.74 hectares). The proposed project is entirely on University Lands, a political subdivision of the State of Texas. The archeological survey was completed under Texas Antiquities Permit No. 9012. The cultural resources field investigation on University Lands was conducted on February 26, 2019 by ENERCON archeologist Gary Edington, who meets the U.S. Secretary of the Interior’s Professional Qualification Standards for archeology as set forth in 36 CFR 61, and consisted of an intensive pedestrian survey utilizing transects spaced no greater than 15 m apart, with shovel tests in areas which had the potential for buried cultural resources. The field investigation was conducted in accordance with the Texas Historical Commission (THC) Archeological Survey Standards for Texas. The entire project was supervised by Michael Margolis, an ENERCON archeologist who meets the U.S. Secretary of the Interior’s Professional Qualification Standards for archeology as set forth in 36 CFR 61. The cultural resources survey did not result in finding any historic or prehistoric artifacts, features, cultural lenses, or sites over 50 years of age on University Lands. Therefore, it is recommended that the project will have no effect on any historic property that may qualify for inclusion in the National Register of Historic Places (NRHP) on University Lands. No further cultural resources investigations are recommended prior to construction of the proposed Olifant Eight Inch Pipeline Project on University Lands. If cultural material, including sites, features, or artifacts that are 50 years old or older are encountered within the ROW during construction of this project, work in the area must cease and the THC must be immediately be notified