RadOnc: An R Package for Analysis of Dose-Volume Histogram and Three-Dimensional Structural Data

Purpose/Objectives: Dose volume histogram (DVH) data are generally analyzed within the context of a treatment planning system (TPS) on a per-patient basis, with evaluation of single-plan or comparative dose distributions. However, TPS software generally cannot perform simultaneous comparative dosimetry among a cohort of patients. The same limitations apply to parallel analyses of three-dimensional structures and other clinical data. Materials/Methods: We developed a suite of tools ("RadOnc" package) using R statistical software to better compare pooled DVH data and empower analysis of structure data and clinical correlates. Representative patient data were identified among previously analyzed adult (n=13) and pediatric (n=1) cohorts and these data were used to demonstrate the performance and functionality of the RadOnc package. Results: The RadOnc package facilitates DVH data import from the TPS and includes automated methods for DVH visualization, dosimetric parameter extraction, statistical comparison among multiple DVHs, basic three-dimensional structural processing, and visualization tools to enable customizable production of publication-quality images. Conclusions: The RadOnc package provides a potent clinical research tool with the ability to integrate robust statistical software and dosimetric data from cohorts of patients. It is made freely available to the community for their current use and remains under active development

Political discussion network homogeneity and partisan selective exposure

This thesis examines the nature of political discussion networks in the period leading up to the 2016 presidential election and the relationship between discussion network composition and partisan selective exposure. Using a nationally representative panel survey, this research examines the partisan makeup of discussion networks across sociodemographic factors, evaluating mainstream media narratives that attribute surprise at Donald Trump’s victory within to voting blocs insulating themselves from alternative views. It also examines whether there is a relationship over time between discussion network partisanship and homogeneity and partisan selective exposure. It finds differences in network partisanship and network partisan distance from ego across respondent partisan affiliation, race, and income consistent with a theoretical framework that suggests partisan sorting is an indirect result of geographic sorting. Further, it concludes that there is a relationship between network partisan distance from ego and subsequent selective exposure, in line theoretical models in which discussion with like-minded alters reinforces partisan attitudes, which lead to further selective exposureRadio-Television-Fil

Liquid-Vapor Equilibrium of Multicomponent Cryogenic Systems

Liquid-vapor and solid-vapor equilibria at low to moderate pressures and low temperatures are important in many solar system environments, including the surface and clouds of Titan, the clouds of Uranus and Neptune, and the surfaces of Mars and Triton. The familiar cases of ideal behavior are limiting cases of a general thermodynamic representation for the vapor pressure of each component in a homogeneous multicomponent system. The fundamental connections of laboratory measurements to thermodynamic models are through the Gibbs-Duhem relation and the Gibbs-Helmholtz relation. Using laboratory measurements of the total pressure, temperature, and compositions of the liquid and vapor phases at equilibrium, the values of these parameters can be determined. The resulting model for vapor-liquid equilibrium can then conveniently and accurately be used to calculate pressures, compositions, condensation altitudes, and their dependencies on changing climatic conditions. A specific system being investigated is CH4-C2H6-N2, at conditions relevant to Titan's surface and atmosphere. Discussed are: the modeling of existing data on CH4-N2, with applications to the composition of Titan's condensate clouds; some new measurements on the CH4-C2H6 binary, using a high-precision static/volumetric system, and on the C2H6-N2 binary, using the volumetric system and a sensitive cryogenic flow calorimeter; and describe a new cryogenic phase-equilibrium vessel with which we are beginning a detailed, systematic study of the three constituent binaries and the ternary CH4-C2H6-N2 system at temperatures ranging from 80 to 105 K and pressures from 0.1 to 7 bar

An Invertible Transform for Efficient String Matching in Labeled Digraphs

Let G = (V, E) be a digraph where each vertex is unlabeled, each edge is labeled by a character in some alphabet ?, and any two edges with both the same head and the same tail have different labels. The powerset construction gives a transform of G into a weakly connected digraph G\u27 = (V\u27, E\u27) that enables solving the decision problem of whether there is a walk in G matching an arbitrarily long query string q in time linear in |q| and independent of |E| and |V|. We show G is uniquely determined by G\u27 when for every v_? ? V, there is some distinct string s_? on ? such that v_? is the origin of a closed walk in G matching s_?, and no other walk in G matches s_? unless it starts and ends at v_?. We then exploit this invertibility condition to strategically alter any G so its transform G\u27 enables retrieval of all t terminal vertices of walks in the unaltered G matching q in O(|q| + t log |V|) time. We conclude by proposing two defining properties of a class of transforms that includes the Burrows-Wheeler transform and the transform presented here

Explicit Models for Threefolds Fibred by K3 Surfaces of Degree Two

We consider threefolds that admit a fibration by K3 surfaces over a nonsingular curve, equipped with a divisorial sheaf that defines a polarisation of degree two on the general fibre. Under certain assumptions on the threefold we show that its relative log canonical model exists and can be explicitly reconstructed from a small set of data determined by the original fibration. Finally we prove a converse to the above statement: under certain assumptions, any such set of data determines a threefold that arises as the relative log canonical model of a threefold admitting a fibration by K3 surfaces of degree two.Comment: Early sections have been restructured and shortened. Assumptions required for the main construction have been weakened. Final version, accepted for publication by the Canadian Journal of Mathematic

A numerical study of the correspondence between paths in a causal set and geodesics in the continuum

This paper presents the results of a computational study related to the path-geodesic correspondence in causal sets. For intervals in flat spacetimes, and in selected curved spacetimes, we present evidence that the longest maximal chains (the longest paths) in the corresponding causal set intervals statistically approach the geodesic for that interval in the appropriate continuum limit.Comment: To the celebration of the 60th birthday of Rafael D. Sorki

Sub-surface Expression of Sand Volcanoes in the Avon-Heathcote Estuary Induced by the Darfield Earthquake; Analog for Sedimentary Structures in the Rock Record

Among the deformation features produced in Christchurch by the September 4th Darfield Earthquake were numerous and widespread “sand volcanoes”. Most of these structures occurred in urban settings and “erupted” through a hardened surface of concrete or tarseal, or soil. Sand volcanoes were also widespread in the Avon‐ Heathcote Estuary and offered an excellent opportunity to readily examine shallow subsurface profiles and as such the potential appearance of such structures in the rock record

Heuristic responses to pandemic uncertainty: Practicable communication strategies of “reasoned transparency” to aid public reception of changing science

Scientific uncertainty during pandemic outbreaks poses a challenge for health communicators. Debates continue over the extent to which health officials should be transparent about uncertainty and the extent to which they should suppress uncertainty and risk losing the public’s trust when information changes. The middle ground, the concept of “reasoned transparency,” proposes that communicators focus on interpreting uncertainty to the public in ways informed by risk research. However, little guidance exists for health officials on how to do so in this context. After conducting a series of one-to-one interviews about people’s coronavirus disease 2019 information habits, we identified significant trends in the heuristics that people depended on to process uncertainty. Based on those trends, we propose health communicators use narratives of science as evolving to set expectations for change, and that when changes do occur, health communicators note divergences from the past and avoid simply replacing old information with new information