Near-ionization-threshold emission in atomic gases driven by intense sub-cycle pulses

We study theoretically the dipole radiation of a hydrogen atom driven by an intense sub-cycle pulse. The time-dependent Schr\"odinger equation for the system is solved by ab initio calculation to obtain the dipole response. Remarkably, a narrowband emission lasting longer than the driving pulse appears at a frequency just above the ionization threshold. An additional calculation using the strong field approximation also recovers this emission, which suggests that it corresponds to the oscillation of nearly-bound electrons that behave similarly to Rydberg electrons. The predicted phenomenon is unique to ultrashort driving pulses but not specific to any particular atomic structure.Comment: 8 pages, 2 figure

Phylogenetic reanalysis of Strauch\u27s osteological data set for the Charadriiformes

Strauch\u27s (1978) compatibility analysis of relationships among the shorebirds (Charadriiformes) was the first study to examine the full range of charadriiform taxa in a reproducible way. Subsequently Mickevich and Parenti (1980) leveled serious charges against Strauch\u27s characters, method of phylogenetic inference, and results. To account for these charges, Strauch\u27s characters were re-examined and recoded, and parsimony analyses were performed on the revised matrix. A parsimony analysis on 74 taxa from the revised matrix yielded 855 shortest trees, each length = 286 and consistency index = 0.385. In each shortest tree there were two major lineages, a lineage of sandpiper-like birds and a lineage of plover-like birds; the two formed a monophyletic group, with the auks (Alcidae) being that group’s sister taxon. The shortest trees were then compared with other estimates of shorebird relationships, comparison suggesting that the charges against Strauch\u27s results may have resulted from the Mickevich and Parenti decisions to exclude much of Strauch\u27s character evidence

Historical Examination Of Delayed Plumage Maturation In The Shorebirds (Aves: Charadriiformes)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137446/1/evo01315.pd

On rectification and enrichment of infinity properads

We develop a theory of infinity properads enriched in a general symmetric monoidal infinity category. These are defined as presheaves, satisfying a Segal condition and a Rezk completeness condition, over certain categories of graphs. In particular, we introduce a new category of level graphs which also allow us to give a framework for algebras over an enriched infinity properad. We show that one can vary the category of level graphs without changing the underlying theory. We also show that infinity properads cannot always be rectified, indicating that a conjecture of the second author and Robertson is unlikely to hold. This stands in stark contrast to the situation for infinity operads, and we further demarcate these situations by examining the cases of infinity dioperads and infinity output properads. In both cases, we provide a rectification theorem that says that each up-to-homotopy object is equivalent to a strict one.Comment: 95 pages. Feedback, comments, and questions are welcome. Updates will be made available at https://github.com/phck/infinity-properad

Finite Element Modeling of Transient Thermography Inspection of Composite Materials

Several finite element models of defects such as debond and void have been developed for composite panels subjected to transient thermography inspection. Since the exact nature of the heat generated from the flash lamps is unknown, direct comparison between FEA and experimental results is not possible. However, some similarity of the results has been observed. The shape of the time curve that simulates the heat flux from the flash lamps has minimal effect on the temperature profiles. Double the number of flash lamps could increase the contrast of thermal image and define the shape of defect better