Collars and partitions of hyperbolic cone-surfaces

For compact Riemann surfaces, the collar theorem and Bers' partition theorem are major tools for working with simple closed geodesics. The main goal of this paper is to prove similar theorems for hyperbolic cone-surfaces. Hyperbolic two-dimensional orbifolds are a particular case of such surfaces. We consider all cone angles to be strictly less than $\pi$ to be able to consider partitions.Comment: 11 pages, 9 figures; v2: minor changes, to appear in Geometriae Dedicat

Predictors of Peripartum Care Attendance Among a Sample of African American Women at Increased Risk for Poor Prenatal Care Compliance

Prenatal and postpartum care are important for reducing maternal and infant morbidity. Racial and ethnic disparities are prevalent in maternal peripartum health and infant birth outcomes as well as peripartum care access and utilization. They highlight the need to identify and better understand correlates of poor prenatal and postpartum care compliance. While risk factors for low adherence to peripartum care have been identified, no studies have looked specifically at predictors of prenatal and postpartum care attendance in an at-risk sample of African American pregnant women. Using existing data from an RCT targeting maternal and infant health disparities and comparing a patient navigation/behavioral incentive intervention to treatment as usual, the present study sought to identify predictors of prenatal and postpartum care attendance. Participants were African American women at risk for poor prenatal care compliance, who participated in the RCT and had a documented live birth (n=123). Using hierarchical linear and logistic regression, the study identified predictors of prenatal and postpartum care attendance, respectively. The study found high-risk pregnancy (p \u3c .001) and fewer barriers to care (p = .013) significantly predicted better prenatal care attendance. Less than adequate prenatal care attendance significantly predicted postpartum visit nonattendance (p \u3c .001). In addition, given that study participants were limited to women who provided informed consent to RCT participation, the present study also examined representativeness of the clinical trial sample. Specifically, women who consented to the RCT (consenters; n=149) were compared to those who did not (non-consenters; n=122) on a variety of demographic and psychosocial variables using chi-square for categorical variables and t-tests for continuous variables. Consenters and non-consenters differed only on education level, with consenters more likely to have at least a high school education than non-consenters. The present study provides benchmark data on sample representativeness and predictors of peripartum care in a clinical trial of strategies to improve prenatal care compliance. These findings could have important implications for healthcare system changes and treatment interventions among this population

Authors’ Reply to “Training and Supporting Residents, for All Family Medicine Practice Settings.”

TO THE EDITOR: We appreciate Dr Wu’s comments and agree wholeheartedly that meeting community needs and negotiating relationships are essential skills for all family physicians. The need for these skills is amplified in the intimacy of the rural environment, as physicians navigate daily life amongst patients at grocery stores, restaurants, schools, and social gatherings

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago. 2. Lake, Marine, and Terrestrial Sediments

Part 1 of this study investigated evidence of biomass burning in global ice records, and here we continue to test the hypothesis that an impact event at the Younger Dryas boundary (YDB) caused an anomalously intense episode of biomass burning at ∼12.8 ka on a multicontinental scale (North and South America, Europe, and Asia). Quantitative analyses of charcoal and soot records from 152 lakes, marine cores, and terrestrial sequences reveal a major peak in biomass burning at the Younger Dryas (YD) onset that appears to be the highest during the latest Quaternary. For the Cretaceous-Tertiary boundary (K-Pg) impact event, concentrations of soot were previously utilized to estimate the global amount of biomass burned, and similar measurements suggest that wildfires at the YD onset rapidly consumed ∼10 million km2 of Earth’s surface, or ∼9% of Earth’s biomass, considerably more than for the K-Pg impact. Bayesian analyses and age regressions demonstrate that ages for YDB peaks in charcoal and soot across four continents are synchronous with the ages of an abundance peak in platinum in the Greenland Ice Sheet Project 2 (GISP2) ice core and of the YDB impact event (12,835–12,735 cal BP). Thus, existing evidence indicates that the YDB impact event caused an anomalously large episode of biomass burning, resulting in extensive atmospheric soot/dust loading that triggered an “impact winter.” This, in turn, triggered abrupt YD cooling and other climate changes, reinforced by climatic feedback mechanisms, including Arctic sea ice expansion, rerouting of North American continental runoff, and subsequent ocean circulation changes