Student Involvement As A Mediator Of The Relationship Of Peer Leaders In First-Year Seminars To Academic Achievement And Persistence

Peer leaders as a component of First-Year Seminars (FYS) are designed to assist in the adjustment, satisfaction and persistence of first-year college students. Although previous studies have consistently found the positive and direct impact of peer leaders on first-year students’ academic achievement and persistence, there is still a lack of clear understanding on why peer leaders have this positive relationship with students’ academic achievement and persistence. Thus, drawing on Astin’s theory of student involvement for higher education (1984, 1993, 1996), and Tinto’s interactive theory of departure (1993), this short term longitudinal study examined the process through which peer leaders resulted in improving students’ academic achievement and persistence. Specifically, this study tested a mediational model of the relationship among FYS peer leaders, student involvement, end-of-first-year GPA and second-year persistence. This study also compared the effects of different peer leader types (i.e., undergraduate peer leaders, graduate peer leaders, or no peer leaders) on FYS student outcomes. Results from structural equation modeling to test mediation showed that the relationship between graduate peer leaders and FYS students’ end-of-first-year GPAs was mediated by students’ study hours, a behavioral form of academic involvement. In addition, students’ study hours and end-of-first-year GPAs co-mediated the relationship between graduate peer leaders and students’ second-year persistence. In other words, having a graduate peer leader in the FYS was positively related to students’ study hours, which was in turn positively related to students’ end-of-first-year GPAs, and then led to a higher probability of students’ second-year persistence. The indirect effects on students’ end-of-first-year GPA and second-year persistence did not differ significantly between undergraduate peer leaders and no peer leaders. The significance, limitations, and implications of this study for future research and practice on how peer leaders in FYSs can more effectively promote first-year students’ academic achievement and persistence were also discussed

Silver Transport and Adsorption-Desorption in Soils: Influence of Zinc

Transport of heavy metals such as Ag is affected by several rate-limiting processes including adsorption and release reactions in soils. In this study, the objective was to qualify adsorption-desorption behavior and transport of silver in the different soils. This study also investigated the influence of the presence of Zn on Ag retention and transport in soils. Kinetic batch adsorption-desorption and column experiments were carried out to investigate the adsorption-desorption and transport of silver in soils having different properties in the presence of Zn. Transport of Ag was carried out using miscible-displacement experiments in water saturated soil columns. For all soils, results indicated that adsorption isotherms for Ag were highly nonlinear with greater affinity for Webster soil. Moreover, the presence of Zn resulted in reduced Ag sorption indicative of competitive behavior. Measured Ag breakthrough results (BTCs) from the column experiments indicated highest Ag mobility in Olivier soil whereas Webster soil exhibited least mobility. This finding is based on the Ag recovered and the retardation of the arrival of Ag in the effluent solution. Furthermore, the presence of Zn resulted in enhanced mobility of Ag. A multireaction and transport model (MRTM) that accounted for nonlinear reversible kinetics and irreversible reactions was capable of describing both Ag and Zn transport in all soil columns

Experimental Test of Decoherence Theory using Electron Matter Waves

A controlled decoherence environment is studied experimentally by free electron interaction with semiconducting and metallic plates. The results are compared with physical models based on decoherence theory to investigate the quantum-classical transition. The experiment is consistent with decoherence theory and rules out established Coulomb interaction models in favor of plasmonic excitation models. In contrast to previous decoherence experiments, the present experiment is sensitive to the onset of decoherence.Comment: Submitted to Physical Review Letters. Main Text: 6 pages, 3 figures. Supplemental Material: 3 pages, 5 figure