Blocked-braid Groups

We introduce and study a family of groups $\mathbf{BB}_n$, called the blocked-braid groups, which are quotients of Artin's braid groups $\mathbf{B}_n$, and have the corresponding symmetric groups $\Sigma_n$ as quotients. They are defined by adding a certain class of geometrical modifications to braids. They arise in the study of commutative Frobenius algebras and tangle algebras in braided strict monoidal categories. A fundamental equation true in $\mathbf{BB}_n$ is Dirac's Belt Trick; that torsion through $4\pi$ is equal to the identity. We show that $\mathbf{BB}_n$ is finite for $n=1,2$ and 3 but infinite for $n>3$

Quantum dynamics of the avian compass

The ability of migratory birds to orient relative to the Earth's magnetic field is believed to involve a coherent superposition of two spin states of a radical electron pair. However, the mechanism by which this coherence can be maintained in the face of strong interactions with the cellular environment has remained unclear. This Letter addresses the problem of decoherence between two electron spins due to hyperfine interaction with a bath of spin 1/2 nuclei. Dynamics of the radical pair density matrix are derived and shown to yield a simple mechanism for sensing magnetic field orientation. Rates of dephasing and decoherence are calculated ab initio and found to yield millisecond coherence times, consistent with behavioral experiments

Study of high-speed angular-contact ball bearings under dynamic load

Research program studies behavior of specific high-speed, angular-contact ball bearings. Program is aimed at detailed investigation of ball-separator behavior and lubrication surface-finish effects in a specific gyro wheel

Charter Schools and the Road to College Readiness: The Effects on College Preparation, Attendance and Choice

The analysis here focuses on Boston's charter high schools. For the purpose of this report, an analysis of high schools is both a necessity and a virtue. It is necessary to study high schools because most students applying to charters in earlier grades are not yet old enough to generate data on postsecondary outcomes. Charter high schools are also of substantial policy interest: a growing body of research argues that high school may be too late for cost-effective human capital interventions. Indeed, impact analyses of interventions for urban youth have mostly generated disappointing results.This report is interested in ascertaining whether charter schools, which in Massachusetts are largely budget-neutral, can have a substantial impact on the life course of affected students. The set of schools studied here comes from an earlier investigation of the effects of charter attendance in Boston on test scores.The high schools from the earlier study, which enroll the bulk of charter high school students in Boston, generate statistically and socially significant gains on state assessments in the 10th grade. This report questions whether these gains are sustained

Peripheral volume measurements as indices of peripheral circulatory factors in the cardiovascular orthostatic response

Peripheral volume measurements as indices of circulatory factors in cardiovascular orthostatic respons

Close encounters : spatial distances between people and a robot of mechanistic appearance

Peer reviewe

The NSF/NIH Effect: Surveying the Effect of Data Management Requirements on Faculty, Sponsored Programs, and Institutional Repositories

The scholarly communication landscape is rapidly changing and nowhere is this more evident than in the field of data management. Mandates by major funding agencies, further expanded by executive order and pending legislation in 2013, require many research grant applicants to provide data management plans for preserving and making their research data openly available. However, do faculty researchers have the requisite skill sets and are their institutions providing the necessary infrastructure to comply with these mandates? To answer these questions, three groups were surveyed in 2012: research and teaching faculty, sponsored programs office staff, and institutional repository librarians. Survey results indicate that while faculty desire to share their data, they often lack the skills to do this effectively. Similarly, while repository managers and sponsored programs offices often provide the necessary infrastructure and knowledge, these resources are not being promoted effectively to faculty. The study offers important insights about services academic libraries can provide to support faculty in their data management efforts: providing tools for sharing research data; assisting with describing, finding, or accessing research data; providing information on copyright and ownership issues associated with data sets; and assisting with writing data management plans

Letter of Information

Letter of Information for participants in the study: The Impact of New Data Management Plan Requirements on Faculty, Sponsored Programs, and Institutional Repository Managers

Red-Cockaded Woodpecker Recovery: An Integrated Strategy

Populations of the red-cockaded woodpecker (Picoides borealis) have experienced massive declines since European colonization of North America. This is due to extensive habitat loss and alteration. Logging of old-growth pine forests and alteration of the fire regime throughout the historic range of the species were the primary causes of population decline. Listing of the red-cockaded woodpecker under the Endangered Species Act of 1973, as amended, and increased emphasis on management of non-game species have resulted in efforts to recover remnant populations of the red-cockaded woodpecker in many parts of its historic range. Due to extensive research and adaptive management initiatives much is now known about the elements required for both short- and long-term management of viable populations of red-cockaded woodpeckers. A short-term strategy is crucial because currently available habitat, in nearly all populations, is poor in 1 or more critical respects. Consequently, almost all populations require immediate attention in the short term, to insure suitable midstory and understory conditions, adequate availability of suitable cavities, and restoration of demographic viability through improvements in number and distribution of breeding groups. Management techniques including artificial cavities, cavity entrance restrictors, translocation of birds, prescribed fire, and mechanical and chemical control of woody vegetation are available to achieve these needs. In the long term, cost-effective management of red-cockaded woodpecker populations requires a timber management program and prescribed fire regime that will produce and maintain the stand structure characteristic of high quality nesting and foraging habitat, so that additional intensive management specific to the woodpeckers is no longer necessary. Timber management that achieves this goal and still allows substantial timber harvest is feasible. The implementation of a red-cockaded woodpecker management strategy, as outlined above, represents appropriate ecosystem management in the fire-maintained pine ecosystems of the southeastern United States and will ultimately benefit a great number of additional species of plants and animals adapted to this ecosystem

Sex Chromosome Dosage Compensation in Heliconius Butterflies: Global yet Still Incomplete?

The evolution of heterogametic sex chromosomes is often-but not always-accompanied by the evolution of dosage compensating mechanisms that mitigate the impact of sex-specific gene dosage on levels of gene expression. One emerging view of this process is that such mechanisms may only evolve in male-heterogametic (XY) species but not in female-heterogametic (ZW) species, which will consequently exhibit "incomplete" sex chromosome dosage compensation. However, recent results suggest that at least some Lepidoptera (moths and butterflies) may prove to be an exception to this prediction. Studies in bombycoid moths indicate the presence of a chromosome-wide epigenetic mechanism that effectively balances Z chromosome gene expression between the sexes by reducing Z-linked expression in males. In contrast, strong sex chromosome dosage effects without any reduction in male Z-linked expression were previously reported in a pyralid moth, suggesting a lack of any such dosage compensating mechanism. Here we report an analysis of sex chromosome dosage compensation in Heliconius butterflies, sampling multiple individuals for several different adult tissues (head, abdomen, leg, mouth, and antennae). Methodologically, we introduce a novel application of linear mixed-effects models to assess dosage compensation, offering a unified statistical framework that can estimate effects specific to chromosome, to sex, and their interactions (i.e., a dosage effect). Our results show substantially reduced Z-linked expression relative to autosomes in both sexes, as previously observed in bombycoid moths. This observation is consistent with an increasing body of evidence that some lepidopteran species possess an epigenetic dosage compensating mechanism that reduces Z chromosome expression in males to levels comparable with females. However, this mechanism appears to be imperfect in Heliconius, resulting in a modest dosage effect that produces an average 5-20% increase in male expression relative to females on the Z chromosome, depending on the tissue. Thus our results in Heliconius reflect a mixture of previous patterns reported for Lepidoptera. In Heliconius, a moderate pattern of incomplete dosage compensation persists apparently despite the presence of an epigenetic dosage compensating mechanism. The chromosomal distributions of sex-biased genes show an excess of male-biased and a dearth of female-biased genes on the Z chromosome relative to autosomes, consistent with predictions of sexually antagonistic evolution.This research was supported in part by a NSF postdoctoral fellowshiptoJ.R.W. (DBI-0905698). RNA sequencing was funded by the “Capacity and Capability Challenge Program” from The Genome Analysis Centre, Norwich, UK. The computing for this project was performed on the Community Cluster at the Center for Research Computing at the University of Kansas. Luiqi (Aloy) Gu provided valuable comments on the manuscript.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/gbe/evv156