Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.

Meaningful Learning by Creating Technology-Mediated Knowledge Boundary Objects Between School and the Workplace

Technological innovation has changed the relationship between formal, non-formal, and informal learning leading to rethink the definition of learning context: Activity Theory can help create a model integrating formal and formal learning through collaborative knowledge building involving schools and professionals/employers. Interaction between these two \u201cactivity systems\u201d generates \u201cboundary objects\u201d that can be useful in both the educational setting and the workplace. This process can provide students with meaningful situated learning experiences that boost their motivation and interest, just because they are based on real-world problems that students will face in their future jobs