Cosmic Superstring Scattering in Backgrounds

We generalize the calculation of cosmic superstring reconnection probability to non-trivial backgrounds. This is done by modeling cosmic strings as wound tachyon modes in the 0B theory, and the spacetime effective action is then used to couple this to background fields. Simple examples are given including trivial and warped compactifications. Generalization to $(p,q)$ strings is discussed.Comment: 12 pages, 2 figures; v2: references adde

Two Black Hole Holography, Lensing and Intensity

We numerically verify the analysis of the "expanding horizon" theory of Susskind in relation to the 't Hooft holographic conjecture. By using a numerical simulation to work out the image formed by two black holes upon a screen very far away, it is seen that it is impossible for a horizon to hide behind another. We also compute the intensity distribution of such an arrangement.Comment: 10 page

Peripartum cardiomyopathy: diagnosis and management

No abstract available

Word learning and verbal working memory in children with developmental language disorder

Background and aims: Previous research into word learning in children with developmental language disorder (DLD) indicates that the learning of word forms and meanings, rather than form-referent links, is problematic. This difficulty appears to arise with impaired encoding, while retention of word knowledge remains intact. Evidence also suggests that word learning skills may be related to verbal working memory. We aimed to substantiate these findings in the current study by exploring word learning over a series of days. Methods: Fifty children with DLD (mean age 6; 11, 72% male) and 54 age-matched typically developing (TD) children (mean age 6; 10, 56% male) were taught eight novel words across a four-day word learning protocol. Day 1 measured encoding, Days 2 and 3 measured re-encoding, and Day 4 assessed retention. At each day, word learning success was evaluated using Naming, Recognition, Description, and Identification tasks. Results: Children with DLD showed comparable performance to the TD group on the Identification task, indicating an intact ability to learn the form-referent links. In contrast, children with DLD performed significantly worse for Naming and Recognition (signifying an impaired ability to learn novel word forms), and for Description, indicating problems establishing new word meanings. These deficits for the DLD group were apparent at Days 1, 2, and 3 of testing, indicating impairments with initial encoding and re-encoding; however, the DLD and TD groups demonstrated a similar rate of learning. All children found the retention assessments at Day 4 difficult, and there were no significant group differences. Finally, verbal working memory emerged as a significant moderator of performance on the Naming and Recognition tasks, such that children with DLD and poor verbal working memory had the lowest levels of accuracy. Conclusions: This study demonstrates that children with DLD struggle with learning novel word forms and meanings, but are unimpaired in their ability to establish new form-referent links. The findings suggest that the word learning deficit may be attributed to problems with encoding, rather than with retention, of new word knowledge; however, further exploration is required given the poor performance of both groups for retention testing. Furthermore, we found evidence that an impaired ability to learn word forms may only be apparent in children who have DLD and low levels of verbal working memory. Implications: When working with children with DLD, speech-language pathologists should assess word learning using tasks that evaluate the ability to learn word forms, meanings, and form-referent links to develop a profile of individual word learning strengths and weaknesses. Clinicians should also assess verbal working memory to identify children at particular risk of word learning deficits. Future research should explore the notion of optimal intervention intensity for facilitating word learning in children with poor language and verbal working memory

Material Characterization and Real-Time Wear Evaluation of Pistons and Cylinder Liners of the Tiger 131 Military Tank

Material characterisation and wear evaluation of the original and replacement pistons and cylinder-liners of Tiger 131 is reported. Original piston and cylinder-liner were operative in the Tigers’ engine during WWII. The replacement piston and cylinder-liner were used as substitutes and were obtained after failure in two hours of operation in the actual engine. Material characterisation revealed that the original piston was aluminium silicon hypereutectic alloy whereas the replacement piston was aluminium copper alloy with very low silicon content. Both original and replacement cylinder-liners consisted of mostly iron which is indicative of cast iron, a common material for this application. The replacement piston average surface roughness was found to be 9.09 μm while for replacement cylinder-liner it was 5.78 μm

Cooling of cryogenic electron bilayers via the Coulomb interaction

Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.Comment: 9 pages, 5 figure