A survival tree for interval-censored failure time data

Interval-censored failure time data as a general type of survival data often arises in medicine and other applied fields. Survival tree is a flexible predictive method for survival data because no specific assumptions are required. Generalized Log-Rank Test have good power with parameters for interval-censored failure time data. We construct a special test statistic of Generalized Log-Rank Tests, and propose a new survival tree with hyper-parameter by combining the test statistic with Conditional Inference Framework for interval-censored failure time data. The effect of tuning hyper-parameter are discussed and hyperparameter tuning allows the tree method to be more general and flexible. Thus the tree method either improve upon or remain competitive with existing tree method for interval-censored failure time dataICtree, which is a special case of ours. An extensive simulation is executed to assess the predictive performance of our tree methods. Finally, the tree methods are applied to a tooth emergence data

Segregation with social linkages: Evaluating Schelling’s model with networked individuals

This paper generalizes the original Schelling model of racial and residential segregation to a context of variable externalities due to social linkages. In a setting in which individuals’ utility function is a convex combination of a heuristic function à la Schelling, of the distance to friends, and of the cost of moving, the prediction of the original model gets attenuated: the segregation equilibria are not the unique solutions. While the cost of distance has a monotonic pro-status-quo effect, equivalent to that of models of migration and gravity models, if friends and neighbors are formed following independent processes, the location of friends in space generates an externality that reinforces the initial configuration if the distance to friends is minimal, and if the number of friends is high. The effect on segregation equilibria crucially depends on the role played by network externalities

On the Onset of Coherent Phonon Motion in Peierls-Distorted Antimony by Attosecond Transient Absorption

Attosecond extreme-ultraviolet (XUV) transient absorption spectroscopy measurements on the Peierls-distorted phase of the semimetal antimony (Sb) are presented. After excitation by an ultrashort, broad band near-infrared (NIR) pulse, the distortion is (partly) lifted causing the well-known coherent phonon motion of the lattice. While the overall observed dynamics generally follow a displacive excitation model, a delayed onset of the pump-induced carrier dynamics due to hot-carrier thermalization is observed, as well as a large spectral phase dependence in the coherent phonon oscillation. The observed spectral phase dependence in the coherent motion is attributed to significantly different carrier relaxation timescales for carrier energies above and near the Fermi level of the semimetal. A simple theoretical model is presented that considers the carrier relaxation timescales in the displacive phonon model to explain the observed dynamics. The results conclusively show that the overall displacive motion is not solely due to an abrupt displacement of carriers from their equilibrium configuration by the pump pulse and that carrier-relaxation effects need to be considered in the description of the phonon motion. The results furthermore show an effect of NIR field-driven shifts of band-energies, which is observed as a transient reshaping of the core-level absorption features.Comment: 12 pages, 7 figures, 1 tabl

Estimating High-Order Brain Functional Networks in Bayesian View for Autism Spectrum Disorder Identification

Brain functional network (BFN) has become an increasingly important tool to understand the inherent organization of the brain and explore informative biomarkers of neurological disorders. Pearson’s correlation (PC) is the most widely accepted method for constructing BFNs and provides a basis for designing new BFN estimation schemes. Particularly, a recent study proposes to use two sequential PC operations, namely, correlation’s correlation (CC), for constructing the high-order BFN. Despite its empirical effectiveness in identifying neurological disorders and detecting subtle changes of connections in different subject groups, CC is defined intuitively without a solid and sustainable theoretical foundation. For understanding CC more rigorously and providing a systematic BFN learning framework, in this paper, we reformulate it in the Bayesian view with a prior of matrix-variate normal distribution. As a result, we obtain a probabilistic explanation of CC. In addition, we develop a Bayesian high-order method (BHM) to automatically and simultaneously estimate the high- and low-order BFN based on the probabilistic framework. An efficient optimization algorithm is also proposed. Finally, we evaluate BHM in identifying subjects with autism spectrum disorder (ASD) from typical controls based on the estimated BFNs. Experimental results suggest that the automatically learned high- and low-order BFNs yield a superior performance over the artificially defined BFNs via conventional CC and PC

Sex- and age-related differences in the contribution of ultrasound-measured visceral and subcutaneous abdominal fat to fatty liver index in overweight and obese Caucasian adults

Differences in body fat distribution may be a reason for the sex-, age-, and ethnicity-related differences in the prevalence of fatty liver disease (FL). This study aimed to evaluate the sex- and age-related differences in the contribution of visceral (VAT) and subcutaneous (SAT) abdominal fat, measured by ultrasound, to fatty liver index (FLI) in a large sample of overweight and obese Caucasian adults, and to identify the VAT and SAT cut-off values predictive of high FL risk. A cross-sectional study on 8103 subjects was conducted. Anthropometrical measurements were taken and biochemical parameters measured. VAT and SAT were measured by ultrasonography. FLI was higher in men and increased with increasing age, VAT, and SAT. The sex*VAT, age*VAT, sex*SAT, and age*SAT interactions negatively contributed to FLI, indicating a lower VAT and SAT contribution to FLI in men and in the elderly for every 1 cm of increment. Because of this, sex- and age-specific cut-off values for VAT and SAT were estimated. In conclusion, abdominal adipose tissue depots are associated with FLI, but their contribution is sex- and age-dependent. Sex- and age-specific cut-off values of ultrasound-measured VAT and SAT are suggested, but they need to be validated in external populations

Sixteen years of Collaborative Learning through Active Sense-making in Physics (CLASP) at UC Davis

This paper describes our large reformed introductory physics course at UC Davis, which bioscience students have been taking since 1996. The central feature of this course is a focus on sense-making by the students during the five hours per week discussion/labs in which the students take part in activities emphasizing peer-peer discussions, argumentation, and presentations of ideas. The course differs in many fundamental ways from traditionally taught introductory physics courses. After discussing the unique features of CLASP and its implementation at UC Davis, various student outcome measures are presented showing increased performance by students who took the CLASP course compared to students who took a traditionally taught introductory physics course. Measures we use include upper-division GPAs, MCAT scores, FCI gains, and MPEX-II scores.Comment: Also submitted to American Journal of Physic

Sulfur and fluorine degassing from Deccan Traps lavas inferred from pyroxene chemistry: potential for end-Cretaceous volcanic winters

The Cretaceous-Paleogene (K-Pg) mass extinction was a pivotal event in Earth's history and is attributed to the interplay of two major events—the Deccan Traps volcanism and the Chicxulub asteroid impact. We contribute to refine of our understanding of the volcanic stressor for this extinction by investigating the sulfur and fluorine budgets of Deccan lavas from the Western Ghats (India), spanning the K-Pg boundary. Sulfur and fluorine concentrations were analyzed in clinopyroxene phenocrysts from Deccan Traps lavas, by Synchrotron-light X-ray fluorescence (beamline I18, Diamond Light Source, U.K.), and ion probe (CAMECA IMS 1280 at Nordsim Laboratory, Swedish Museum of Natural History, Stockholm, SE), respectively. The results were divided by experimentally determined partition coefficients to calculate melt concentrations. Our analyses reveal variable magmatic volcanic fluorine concentrations ranging from 400 to 3000 parts per million, suggesting the potential for regional environmental impact. The highest sulfur concentrations, reaching up to 1800 parts per million, are observed in Deccan lavas emplaced just prior to the extinction interval, within a timeframe of 0.1 million years. In contrast, later basalts generally exhibit lower sulfur concentrations, only up to 750 parts per million. Independent evidence supports that eruption of the Deccan flood basalts occurred in multiple voluminous eruptive pulses each lasting on the order of centuries, as typical of continental flood basalts. Our findings propose that the volcanic sulfur degassing associated with such activity may have led to repeated, short-lived global temperature drops, too short to be recorded by global paleotemperature record, albeit coupled with a global cooling trend. Sulfur-induced cold snaps likely imposed stress on ecosystems long before the decisive impact of the Chicxulub bolide at the end of the Cretaceous