Voluntary Web-Based Self-Assessment Quiz Use Improves Exam Performance, Especially for Learners with Low Prior Knowledge

We examined students’ voluntary use of digital self-assessment quizzes as a resource for learning in a large anatomy and physiology lecture course. Students (N = 238) could use 16 chapter quizzes and four analogous unit quizzes to rehearse and self-assess knowledge. Repeated use was uncommon (12%), as was lack of use (13%). Most students (75%) engaged in occasional use of self-assessment quiz items. Exam performance differed between repeated use (84%), occasional use (76%), and no use (72%) groups. Differences were greater among students who lacked prior knowledge of course topics. Quiz use improved performance more for low prior knowledge students, and differences increased over the semester. Overall, repeated users significantly outperformed occasional users (+7.5%) and non users (+11.9%) on course examshttps://digitalscholarship.unlv.edu/btp_expo/1023/thumbnail.jp

A TERM STRUCTURE MODEL FOR AGRICULTURAL FUTURES

An extension of Schwartz's model of futures price term structure that includes seasonality is developed. The approach allows futures prices for all maturities to be estimated simultaneously by exploiting arbitrage relationships. An application to wheat futures prices is presented.futures markets, price analysis, Demand and Price Analysis, Marketing,

Lost: The Crisis Of Jobless and Out Of School Teens and Young Adults In Chicago, Illinois and the U.S.

This report contains compilations and calculations of various employment data for males and females 16 to 24 years old by race/ethnicity from 2005 to 2014, comparing Chicago, Illinois, the U.S. and in some instances, adding Los Angeles and New York. Besides an array of figures and tables, the report contains GIS generated maps that illustrate the relationship between employment data and population distribution by race/ethnicity. A significant contribution of this report is its demonstration that low rates of employment are spatially concentrated in neighborhoods that are also racially segregated. This report clearly highlights that youth employment rates are tied to conditions in neighborhoods and cannot be seen as distinct from what is happening in the neighborhoods themselves. The devastation of unemployment in turn, wreaks havoc on the neighborhood

Inelastic neutron scattering signal from deconfined spinons in a fractionalized antiferromagnet

We calculate the contribution of deconfined spinons to inelastic neutron scattering (INS) in the fractionalized antiferromagnet (AF*), introduced elsewhere. We find that the presence of free spin-1/2 charge-less excitations leads to a continuum INS signal above the Neel gap. This signal is found above and in addition to the usual spin-1 magnon signal, which to lowest order is the same as in the more conventional confined antiferromagnet. We calculate the relative weights of these two signals and find that the spinons contribute to the longitudinal response, where the magnon signal is absent to lowest order. Possible higher-order effects of interactions between magnons and spinons in the AF* phase are also discussed.Comment: 9 page

The Role of Pregnancy Concerns in the Relationship between Substance Use and Unprotected Sex among Adolescents

BACKGROUND: Substance use and unprotected sex are prevalent among adolescents. The link between substance use and unprotected sex is well-established. Research has also highlighted how adolescents' attitudes and risk perceptions regarding unprotected sex, including concerns about pregnancy ("Getting pregnant would force me to grow up too fast"), are associated with unprotected sex and unplanned pregnancy. However, less research has examined the potential relationship between pregnancy concerns and substance use among adolescents. OBJECTIVES: The study prospectively examined (1) differences in pregnancy concerns across patterns of substance use and (2) whether pregnancy concerns mediate the relationship between substance use and later unprotected sex among a sample of middle and high school students. METHOD: 98 adolescents [M(SD) age = 14.28(1.68), 59.4% female, 59.4% black/African American] completed self-report measures of marijuana and alcohol use, pregnancy concerns, and unprotected sex across three time points over 6 months (T1-T3). RESULTS: Substance users (alcohol/marijuana) reported fewer pregnancy concerns compared to non-substance users (t = 2.99, p = .04). Pregnancy concerns at T2 mediated the relationship between T1 lifetime substance use and later unprotected sex (T3) (indirect effect: b = 0.10, CI[.01-.41]; direct effect: b = 0.15, p = .32), controlling for gender, age, and race. More frequent substance use (T1) was related to fewer pregnancy concerns at T2 (b = -0.10, p = .04); fewer pregnancy concerns were related to increased likelihood of later unprotected sex (b = -1.02, p = .02). CONCLUSIONS: Findings offer new insight into associations between substance use and unprotected sex and suggest that substance use and sexual health interventions should target pregnancy concerns

Electron Transport Driven by Nonequilibrium Magnetic Textures

Spin-polarized electron transport driven by inhomogeneous magnetic dynamics is discussed in the limit of a large exchange coupling. Electron spins rigidly following the time-dependent magnetic profile experience spin-dependent fictitious electric and magnetic fields. We show that the electric field acquires important corrections due to spin dephasing, when one relaxes the spin-projection approximation. Furthermore, spin-flip scattering between the spin bands needs to be taken into account in order to calculate voltages and spin accumulations induced by the magnetic dynamics. A phenomenological approach based on the Onsager reciprocity principle is developed, which allows us to capture the effect of spin dephasing and make a connection to the well studied problem of current-driven magnetic dynamics. A number of results that recently appeared in the literature are related and generalized.Comment: 4 pages, 1 figur