Students’ definitions of lexically ambiguous mathematical vocabulary

Fifty-five students in three high school geometry classes participated in a vocabulary survey asking them to write out, exemplify, and/or illustrate with drawings their definitions for fifteen mathematical vocabulary words: acute, area, coordinate, diagonal, difference, exponent, factor, irrational, mean, multiple, prime, product, reduce, square, and variable. All of these terms are characterized by lexical ambiguity, meaning that they have different meanings in different contexts. The students' responses were analyzed qualitatively, driven by the following research questions. First, in light of past studies in which findings seem consistently to reveal that a large portion of the participants have inadequate comprehension and/or inability to articulate their understanding of "basic" mathematical vocabulary, what are students' ideas about the meanings of certain vocabulary words? What strands or themes of meaning attributed to the words are evident from students' responses? Do students' responses seem to indicate that lexical ambiguity causes confusion for them in their definitions? A variety of ideas and interpretations emerged from the students responses for each of the words. Some of the students' ideas conformed to conventional mathematical definitions of the terms, but many were also characterized by vagueness or confusion. Interference from the lexical ambiguity of some of the words did appear in the data, particularly with the terms diagonal, irrational, and prime. A secondary purpose of this research was driven by the question: what forms of written expression do the students use to communicate their meanings for the vocabulary words posed to them? After a preliminary analysis of the data from the surveys through systematic theoretical sampling, nine students were selected to participate in follow-up interviews in which supplementary information was gathered. The interview method utilized stimulated recall, and the interviews were video-taped and transcribed. Because students construct their own individual meanings for mathematical terminology, their ideas about specific words do reflect a spectrum of interpretations. Through focused discussion and articulation of meaning where lexical ambiguity exists, students can more confidently enter into mathematical communication and discourse.Education, Faculty ofCurriculum and Pedagogy (EDCP), Department ofGraduat

Markers of Successful Extubation in Extremely Preterm Infants, and Morbidity After Failed Extubation

To identify variables associated with successful elective extubation, and to determine neonatal morbidities associated with extubation failure in extremely preterm neonates. This study was a secondary analysis of the National Institute of Child Health and Human Development Neonatal Research Network's Surfactant, Positive Pressure, and Oxygenation Randomized Trial that included extremely preterm infants born at 240/7 to 276/7 weeks' gestation. Patients were randomized either to a permissive ventilatory strategy (continuous positive airway pressure group) or intubation followed by early surfactant (surfactant group). There were prespecified intubation and extubation criteria. Extubation failure was defined as reintubation within 5 days of extubation. Of 1316 infants in the trial, 1071 were eligible; 926 infants had data available on extubation status; 538 were successful and 388 failed extubation. The rate of successful extubation was 50% (188/374) in the continuous positive airway pressure group and 63% (350/552) in the surfactant group. Successful extubation was associated with higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within the first 24 hours of age and prior to extubation, lower partial pressure of carbon dioxide prior to extubation, and non-small for gestational age status after adjustment for the randomization group assignment. Infants who failed extubation had higher adjusted rates of mortality (OR 2.89), bronchopulmonary dysplasia (OR 3.06), and death/ bronchopulmonary dysplasia (OR 3.27). Higher 5-minute Apgar score, and pH prior to extubation, lower peak fraction of inspired oxygen within first 24 hours of age, lower partial pressure of carbon dioxide and fraction of inspired oxygen prior to extubation, and nonsmall for gestational age status were associated with successful extubation. Failed extubation was associated with significantly higher likelihood of mortality and morbidities. ClinicalTrials.gov: NCT00233324

Growth Rates of Infants Randomized to Continuous Positive Airway Pressure or Intubation After Extremely Preterm Birth.

Objective To evaluate the effects of early treatment with continuous positive airway pressure (CPAP) on nutritional intake and in-hospital growth rates of extremely preterm (EPT) infants. Study design EPT infants (240/7-276/7 weeks of gestation) enrolled in the Surfactant Positive Airway Pressure and Pulse Oximetry Trial (SUPPORT) were included. EPT infants who died before 36 weeks of postmenstrual age (PMA) were excluded. The growth rates from birth to 36 weeks of PMA and follow-up outcomes at 18-22 months corrected age of EPT infants randomized at birth to either early CPAP (intervention group) or early intubation for surfactant administration (control group) were analyzed. Results Growth data were analyzed for 810 of 1316 infants enrolled in SUPPORT (414 in the intervention group, 396 in the control group). The median gestational age was 26 weeks, and the mean birth weight was 839 g. Baseline characteristics, total nutritional intake, and in-hospital comorbidities were not significantly different between the 2 groups. In a regression model, growth rates between birth and 36 weeks of PMA, as well as growth rates during multiple intervals from birth to day 7, days 7-14, days 14-21, days 21-28, day 28 to 32 weeks PMA, and 32-36 weeks PMA did not differ between treatment groups. Independent of treatment group, higher growth rates from day 21 to day 28 were associated with a lower risk of having a Bayley-III cognitive score Conclusions EPT infants randomized to early CPAP did not have higher in-hospital growth rates than infants randomized to early intubation