486 research outputs found
63rd Commencement Address
Judge Wald offers advice to graduates, including: But the most valuable legacy college can leave you Is an appetite and appreciation of language. Clarity, lucidity, precision with words is the most elusive of talents. Words inform, inspire, mislead and sometimes destroy. They are the most essential tool of humanity. Words plan, build, preserve, and often demolish civilizations, industries, empires, governments, and relationships. If you carry one lesson from college to life, let it be the knowledge that what you say is the expression of what you mean, what you intend to provoke in others, what you want to realize
Sex-related Differences in Aging Rate Are Associated with Sex Chromosome System in Amphibians
Sex-related differences in mortality are widespread in the animal kingdom. Although studies have shown that sex determination systems might drive lifespan evolution, sex chromosome influence on aging rates have not been investigated so far, likely due to an apparent lack of demographic data from clades including both XY (with heterogametic males) and ZW (heterogametic females) systems. Taking advantage of a unique collection of captureârecapture datasets in amphibians, a vertebrate group where XY and ZW systems have repeatedly evolved over the past 200 million years, we examined whether sex heterogamy can predict sex differences in aging rates and lifespans. We showed that the strength and direction of sex differences in aging rates (and not lifespan) differ between XY and ZW systems. Sex-specific variation in aging rates was moderate within each system, but aging rates tended to be consistently higher in the heterogametic sex. This led to small but detectable effects of sex chromosome system on sex differences in aging rates in our models. Although preliminary, our results suggest that exposed recessive deleterious mutations on the X/Z chromosome (the âunguarded X/Z effectâ) or repeat-rich Y/W chromosome (the âtoxic Y/W effectâ) could accelerate aging in the heterogametic sex in some vertebrate clades
Direct Fragmentation of Quarkonia Including Fermi Motion Using Light-cone Wave Function
We investigate the effect of Fermi motion on the direct fragmentation of the
and states employing a light-cone wave function. Consistent
with such a wave function we set up the kinematics of a heavy quark fragmenting
into a quarkonia such that the Fermi motion of the constituents split into
longitudinal as well as transverse direction and thus calculate the
fragmentation functions for these states. In the framework of our
investigation, we estimate that the fragmentation probabilities of and
may increase at least up to 14 percent when including this degree of
freedom.Comment: 7 pages 5 figures Appeared in EPJC; Fig 1 and Appendix revise
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