Pb isotopic studies of airborne particulate matter, incinerator ash, and gasoline have been carried out to determine sources of Pb pollution in urban areas from France and the southern United Kingdom. 206 Pb/ 207 Pb ratios in gasoline range from 1.061 to 1.094 (average values are 1.084 for France and 1.067 for the U.K.) while for industrially-derived Pb, 206 -Pb/ 207 Pb ratios vary from 1.143 to 1.155. Natural Pb is more radiogenic and literature values for pre-industrial sediments give 206 Pb/ 207 Pb ratios of 1.19-1.20 in France and 1.17-1.19 in the U.K. The measured Pb isotopic signature of airborne particulate matter reflects the relative importance of each of these sources, and samples taken from urban areas close to traffic in France and the U.K. show 206 Pb/ 207 Pb ratios that vary widely from 1.085 to 1.158. While alkyl-lead additives in gasoline are typically still the dominant source of Pb in urban particulate matter, the relative importance of gasoline-derived Pb has decreased, and as a result other sources (industrial and natural) can be identified using isotopic studies. This is a consequence of recent EU environmental legislation that significantly limits concentrations of Pb in gasoline and the increased market penetration of unleaded gasoline. In addition, at a given location, the Pb isotopic composition of particulate matter can vary considerably due to temporal variations in sources (i.e., variations in traffic density) and with wind direction.

We examined the effect of the perceived classroom environment on math self-efficacy and the effect of math self-efficacy on standardized math test performance. Upper elementary school students (n = 1163) provided self-reports of their perceived math selfefficacy and the degree to which their math classroom environment was masteryoriented, challenging, and caring. Individual student scores on the California Standards Test for Mathematics were also collected. A series of two-level models revealed that students who perceived their classroom environments as more caring, challenging, and mastery-oriented had significantly higher levels of math efficacy, and higher levels of math efficacy positively predicted math performance. Analysis of the indirect effects of classroom variables on math performance indicated a small significant mediating effect of self-efficacy. Implications for research on self-efficacy and the perceived classroom environment are discussed.Math Self-efficacy 3 Does Math Self-efficacy Mediate the Effect of the Perceived Classroom Environment on Standardized Math Test Performance?In the current high-stakes testing environment, any attribute of a student that positively influences achievement is of interest. The degree to which a student believes that he/she is capable of performing specific tasks, referred to as self-efficacy, is particularly relevant given that self-efficacy has been argued to have powerful effects on achievement behavior (Bandura, 1986). Those with higher self-efficacy are proposed to have higher aspirations, stronger commitments to their goals, and recover more quickly from setbacks than those lower in self-efficacy. Beliefs in one's efficacy can vary across academic subjects (e.g. reading vs. writing) and self-efficacy for mathematics has received close attention. Students with higher math self-efficacy persist longer on difficult math problems and are more accurate in math computations than those lower in math self-efficacy (Collins, 1982; Hoffman & Schraw, 2009). Math self-efficacy is also a stronger predictor of math performance than either math anxiety or previous math experience ( Pajares & Miller, 1994; Pajares & Miller, 1995, respectively) and influences math performance as strongly as overall mental ability (Pajares & Kranzler, 1995).The demonstrated importance of self-efficacy in academic achievement has provoked widespread interest in specific factors that affect a student's self-efficacy beliefs. Bandura's (1997) social-cognitive theory proposed that self-efficacy is most strongly affected by one's previous performance and research largely supports this (Chen & Zimmerman, 2007). His theory also suggests that self-efficacy is affected by observing others (e.g. watching peers succeed at a task), verbal persuasion (e.g. encouragement from parents and teachers), and interpretation of physiological states (e.g. Math Self-efficacy 4 lack of anxiety may be a signal that one possesses skills). Although several studies indicate that manipulating features of learning...