Influence of indomethacin on lens regeneration in the newt notophthalmus viridescens

Following lentectomy newts were injected with indomethacin in a variety of carrier solutions at doses ranging from 1.2–120 mg/kg body weight every other day for 15–17 days. The results show that injection of this drug according to the regimen used has no significant effect on regeneration of the lens. The data suggest, but do not prove, that prostaglandins may not play a major role in the early phases of lens regeneration in the newt.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47503/1/427_2004_Article_BF00848434.pd

Constraining primordial non-Gaussianity with cosmological weak lensing: shear and flexion

We examine the cosmological constraining power of future large-scale weak lensing surveys on the model of \emph{Euclid}, with particular reference to primordial non-Gaussianity. Our analysis considers several different estimators of the projected matter power spectrum, based on both shear and flexion, for which we review the covariances and Fisher matrices. The bounds provided by cosmic shear alone for the local bispectrum shape, marginalized over $\sigma_8$, are at the level of $\Delta f_\mathrm{NL} \sim 100$. We consider three additional bispectrum shapes, for which the cosmic shear constraints range from $\Delta f_\mathrm{NL}\sim 340$ (equilateral shape) up to $\Delta f_\mathrm{NL}\sim 500$ (orthogonal shape). The competitiveness of cosmic flexion constraints against cosmic shear ones depends on the galaxy intrinsic flexion noise, that is still virtually unconstrained. Adopting the very high value that has been occasionally used in the literature results in the flexion contribution being basically negligible with respect to the shear one, and for realistic configurations the former does not improve significantly the constraining power of the latter. Since the flexion noise decreases with decreasing scale, by extending the analysis up to $\ell_\mathrm{max} = 20,000$ cosmic flexion, while being still subdominant, improves the shear constraints by $\sim 10$ when added. However on such small scales the highly non-linear clustering of matter and the impact of baryonic physics make any error estimation uncertain. By considering lower, and possibly more realistic, values of the flexion intrinsic shape noise results in flexion constraining power being a factor of $\sim 2$ better than that of shear, and the bounds on $\sigma_8$ and $f_\mathrm{NL}$ being improved by a factor of $\sim 3$ upon their combination. (abridged)Comment: 30 pages, 4 figures, 4 tables. To appear on JCA

Elasticity and Petri nets

Digital electronic systems typically use synchronous clocks and primarily assume fixed duration of their operations to simplify the design process. Time elastic systems can be constructed either by replacing the clock with communication handshakes (asynchronous version) or by augmenting the clock with a synchronous version of a handshake (synchronous version). Time elastic systems can tolerate static and dynamic changes in delays (asynchronous case) or latencies (synchronous case) of operations that can be used for modularity, ease of reuse and better power-delay trade-off. This paper describes methods for the modeling, performance analysis and optimization of elastic systems using Marked Graphs and their extensions capable of describing behavior with early evaluation. The paper uses synchronous elastic systems (aka latency-tolerant systems) for illustrating the use of Petri nets, however, most of the methods can be applied without changes (except changing the delay model associated with events of the system) to asynchronous elastic systems.Peer ReviewedPostprint (author's final draft

Localized detection of phase transition in tungsten by laser ultrasonics

We demonstrated a method for localized, furnace-free detection of the onsets of melting and ablation in polycrystalline tungsten using nanosecond laser ultrasonics. Pulsed laserinduced melting is characterized by a delay in the arrival of the shear wave with increasing laser peak intensity. Pulse-laser induced ablation was characterized by pronounced increase of the amplitude of the signal associated with the arrival of longitudinal acoustic wave. Both phenomena are attributed to a change in character of the ultrasonic source. The described technique suggests a new spatially resolved method for detection of metal-to-melt phase transition in refractory metals

Localized detection of phase transition in tungsten by laser ultrasonics

We demonstrated a method for localized, furnace-free detection of the onsets of melting and ablation in polycrystalline tungsten using nanosecond laser ultrasonics. Pulsed laserinduced melting is characterized by a delay in the arrival of the shear wave with increasing laser peak intensity. Pulse-laser induced ablation was characterized by pronounced increase of the amplitude of the signal associated with the arrival of longitudinal acoustic wave. Both phenomena are attributed to a change in character of the ultrasonic source. The described technique suggests a new spatially resolved method for detection of metal-to-melt phase transition in refractory metals