Numerical solution of open string field theory in Schnabl gauge

Using traditional Virasoro $L_0$ level-truncation computations, we evaluate the open bosonic string field theory action up to level $(10,30)$. Extremizing this level-truncated potential, we construct a numerical solution for tachyon condensation in Schnabl gauge. We find that the energy associated to the numerical solution overshoots the expected value $-1$ at level $L=6$. Extrapolating the level-truncation data for $L\leq 10$ to estimate the vacuum energies for $L > 10$, we predict that the energy reaches a minimum value at $L \sim 12$, and then turns back to approach $-1$ asymptotically as $L \rightarrow \infty$. Furthermore, we analyze the tachyon vacuum expectation value (vev), for which by extrapolating its corresponding level-truncation data, we predict that the tachyon vev reaches a minimum value at $L \sim 26$, and then turns back to approach the expected analytical result as $L \rightarrow \infty$.Comment: 37 pages, 9 figures, some typos correcte

Learning-by-Doing, Learning-by-Exporting, and Productivity: Evidence from Colombia

The empirical evidence on whether participation in export markets increases plant-level productivity has been inconclusive so far. We explain this inconclusiveness by drawing on Arrow's (1962) characterization of learning-by-doing, which suggests focusing on young plants and using measures of export experience rather than export participation. We find strong evidence of learning-by-exporting for young Colombian manufacturing plants between 1981 and 1991: total factor productivity increases 4%-5% for each additional year a plant has exported, after controlling for the effect of current exports on total factor productivity. Learning-by-exporting is more important for young than for old plants and in industries that deliver a larger percentage of their exports to high-income countries.learning, trade, total factor productivity, exports, export-led growth

Urinary incontinence: A vibration alert system for detecting pad overflow

This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2011 RESNA.A sensor and electronics system is described that monitors the leakage of urine from continence pads into surrounding underwear. Urinary incontinence is involuntary loss of urine and occurs when the bladder muscles contract without warning or the sphincter muscles surrounding the urethra are too weak to prevent leakage. The system comprises a wetness sensor and electronics unit. The sensor is stitched into the underwear and detects overspills of urine from the pad. The electronics unit is attached to the underwear and responds by vibrating, signaling to the wearer that pad has failed. This system has application for individuals who use continence pads in the community, but it could also be used in care homes