Entropic depletion of DNA in triangular nanochannels

Using Monte Carlo simulations of a touching-bead model of double-stranded DNA, we show that DNA extension is enhanced in isosceles triangular nanochannels (relative to a circular nanochannel of the same effective size) due to entropic depletion in the channel corners. The extent of the enhanced extension depends non-monotonically on both the accessible area of the nanochannel and the apex angle of the triangle. We also develop a metric to quantify the extent of entropic depletion, thereby collapsing the extension data for circular, square, and various triangular nanochannels onto a single master curve for channel sizes in the transition between the Odijk and de Gennes regimes.     

Modeling the relaxation time of DNA confined in a nanochannel

Using a mapping between a Rouse dumbbell model and fine-grained Monte Carlo simulations, we have computed the relaxation time of λ-DNA in a high ionic strength buffer confined in a nanochannel. The relaxation time thus obtained agrees quantitatively with experimental data [Reisner et al., Phys. Rev. Lett. 94, 196101 (2005)] using only a single O(1) fitting parameter to account for the uncertainty in model parameters. In addition to validating our mapping, this agreement supports our previous estimates of the friction coefficient of DNA confined in a nanochannel [Tree et al., Phys. Rev. Lett. 108, 228105 (2012)], which have been difficult to validate due to the lack of direct experimental data. Furthermore, the model calculation shows that as the channel size passes below approximately 100 nm (or roughly the Kuhn length of DNA) there is a dramatic drop in the relaxation time. Inasmuch as the chain friction rises with decreasing channel size, the reduction in the relaxation time can be solely attributed to the sharp decline in the fluctuations of the chain extension. Practically, the low variance in the observed DNA extension in such small channels has important implications for genome mapping.     

The attitudes and opinions of high school sports participants: an exploratory empirical examination

Sport scholars and public commentators have long held both positive and critical opinions about the influence of athletic involvement on participants and their perceptions of the social world. Yet for all of the strong claims and deeply held assumptions, relatively little empirical data or social scientific analysis have been available. This study begins to address this deficiency using new data from a nationally representative survey of American high school students. We compare sports participants and their peers in terms of concern for social problems, interracial contact and attitudes, views of gender roles and sex-based discrimination and political orientation. We find participants and non-participants differ very little in their social concern and views of gender roles and sex-based discrimination, while significant differences were found in levels of interracial contact, views on race relations and political orientation. In view of these findings, we make some general conclusions about the social influence of sport in the lives of American youth and how this topic may be further explored in subsequent work.     

Creating an alternate reality: Critical,creative, and empathic thinking generated in the Global Village Playground capstone experience

The Global Village Playground (GVP) was a capstone learning experience designed to address institutional assessment needs while providing an integrated and authentic learning experience for students aimed at fostering critical and creative thinking. In the GVP, students work on simulated and real-world problems as a design team tasked with developing an alternate reality game that makes an impact on the United Nations Millennium Development Goals. Researchers employed a qualitative case study approach to evaluate participant reactions to the course, their perceptions of the instructional design methodology, what they learned in the course, and the challenges they experienced during the pilot implementation of this capstone design. This article documents what students reported to have learned in the course as a result of their experience creating an alternate reality game.     

e-Voting intent: A comparison of young and elderly voters

The ability to vote online has the potential to increase voter turnout for elections due to increased convenience over traditional voting polls. This study examines factors that can affect a citizen's intent to vote online. Survey subjects came from two different age groups: young adults, 18–25 years of age; and senior citizens, ages 60 plus. Using the Unified Theory of Acceptance and Use of Technology (UTAUT), the study found that performance expectancy, effort expectancy, social influence, trust in the internet, and computer anxiety were significantly related to intent to use online voting. Trust in the government was insignificant. Performance expectancy, social influence, and computer anxiety were related to intent to vote online for both young adults and seniors. Effort expectancy was related to intent to vote for the seniors but not young adults, and trust in the internet was related to intent to vote for young adults but not seniors.     

Matching meaning for cross-language information retrieval

This article describes a framework for cross-language information retrieval that efficiently leverages statistical estimation of translation probabilities. The framework provides a unified perspective into which some earlier work on techniques for cross-language information retrieval based on translation probabilities can be cast. Modeling synonymy and filtering translation probabilities using bidirectional evidence are shown to yield a balance between retrieval effectiveness and query-time (or indexing-time) efficiency that seems well suited large-scale applications. Evaluations with six test collections show consistent improvements over strong baselines.     

Posttrial injections of strychnine sulfate: Facilitation of consolidation or retrieval?

The existing literature demonstrating that animals given strychnine sulfate shortly after training display enhanced retention 24 h later can be interpreted in terms of either consolidation or retrieval processes. A test between these two interpretations failed to support the consolidation interpretation, but did support the retrieval interpretation. It was concluded that (a) a retrieval model provides an adequate interpretation of the facilitation of retention resulting from posttrial injections of strychnine, and (b) an unambiguous demonstration that strychnine enhances processes of consolidation has yet to be offered.