The nonperturbative closed string tachyon vacuum to high level

We compute the action of closed bosonic string field theory at quartic order with fields up to level ten. After level four, the value of the potential at the minimum starts oscillating around a nonzero negative value, in contrast with the proposition made in [5]. We try a different truncation scheme in which the value of the potential converges faster with the level. By extrapolating these values, we are able to give a rather precise value for the depth of the potential.Comment: 24 pages. v2: typos corrected, clarified extrapolation in scheme B, and added extrapolated tachyon and dilaton vev's at the end of Section

Short Courses: Flexible Learning Opportunities in Informatics

In today’s fast-paced, data-driven world, researchers need to have a good foundation in informatics to store, organize, process, and analyze growing amounts of data. However, not all degree programs offer such training. Obtaining training in informatics on your own can be a daunting task for both new and established researchers who have little informatics experience. Providing educational opportunities appropriate for various skill levels and that mesh with a full-time schedule can remove barriers and foster a collaborative, informatics-savvy community that is better equipped to push science forward. To enhance informatics education in bioinformatics, VCUs Wright Center for Clinical and Translational Research of- fers a complementary series of seminars and workshops. These short course offerings introduce attendees to bioinformatics concepts and applications, and provide hands-on experience using online Bioinformatics databases. Bioinformatics 101 (B101) is an 8-week long series of 1-hour seminars focused on introducing topics in bioinformatics related to Next Generation Sequencing (NGS). Lectures are application focused and include overviews of NGS technology, practical bioinformatics pipelines, and examples of how the technology can influence downstream bioinformatics analyses. Bioinformatics 102 (B102) is a 5-day, 2 hours per day workshop developed in collaboration with VCU Libraries that provides attendees with hands-on experience accessing and using public data repositories. Sessions include a brief lecture followed by hands-on exercises. A Certificate of Completion is awarded upon meeting certain criteria for either the 101 or 102 courses. Bioinformatics 101 has been offered 3 times with a combined total of 246 registrants, and Bioinformatics 102 has been offered twice with a total of 78 registrants (limited to 30 per session per day). From course surveys, 82% (n=108) and 95% (n=47) of respondents gave B101 and B102 a positive rating, respectively. In addition, 89% of B101 respondents indicated their knowledge was improved, with 100% of B102 respondents indicating the same. A total of 84 and 33 certificates have been awarded for B101 and B102, respectively. The Bioinformatics 101 and 102 courses have become highly anticipated across the university, and have gained the external attention of surrounding businesses and colleges. Registrants have diverse backgrounds including biological, clinical, computational, administrative, librarian, business, and others with a total of 77 departments across VCU and VCU Health represented. Due to this interest, Bioinformatics 101 began offering live online attendance to accommodate those who were unable to travel across campus, or who are attending from outside VCU. This past year, 50% of attendance was online indicating a growing need for flexible education opportunities in informatics. Increasing researcher knowledge of Bioinformatics along with awareness of university resources for informatics support fosters an informatics-savvy research community that is empowered to take advantage of existing and new data sources in the pursuit of new insights and scientific discoveries for the betterment of human health. Future work will include the development of a more comprehensive educational framework by creating new and flexible learning opportunities that will make informatics education easy and convenient for our dedicated researchers

Testing Closed String Field Theory with Marginal Fields

We study the feasibility of level expansion and test the quartic vertex of closed string field theory by checking the flatness of the potential in marginal directions. The tests, which work out correctly, require the cancellation of two contributions: one from an infinite-level computation with the cubic vertex and the other from a finite-level computation with the quartic vertex. The numerical results suggest that the quartic vertex contributions are comparable or smaller than those of level four fields.Comment: 14 pages, LaTeX. v2: New references to work of Beccaria and Rampino, and Taylor. Improved numerical analysis at the end of section

Planck Fluctuations, Measurement Uncertainties and the Holographic Principle

Starting from a critical analysis of recently reported surprisingly large uncertainties in length and position measurements deduced within the framework of quantum gravity, we embark on an investigation both of the correlation structure of Planck scale fluctuations and the role the holographic hypothesis is possibly playing in this context. While we prove the logical independence of the fluctuation results and the holographic hypothesis (in contrast to some recent statements in that direction) we show that by combining these two topics one can draw quite strong and interesting conclusions about the fluctuation structure and the microscopic dynamics on the Planck scale. We further argue that these findings point to a possibly new and generalized form of quantum statistical mechanics of strongly (anti)correlated systems of degrees of freedom in this fundamental regime.Comment: 19 pages, Latex, no figures, some new references, to appear ModPhysLett

Generalized Sagnac Effect

Experiments were conducted to study light propagation in a light waveguide loop consisting of linearly and circularly moving segments. We found that any segment of the loop contributes to the total phase difference between two counterpropagating light beams in the loop. The contribution is proportional to a product of the moving velocity v and the projection of the segment length Deltal on the moving direction, Deltaphi=4pivDeltal/clambda. It is independent of the type of motion and the refractive index of waveguides. The finding includes the Sagnac effect of rotation as a special case and suggests a new fiber optic sensor for measuring linear motion with nanoscale sensitivity.Comment: 3 pages (including 3 figures