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Variable temperature dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy (FTIR) have been combined and applied to rheooptical (DMA-FTIR) studies of thin films of a poly(ester urethane). In this study, dynamic infrared linear dichroism (DIRLD) measurements have been carried out at 25, -5, and -30°C with the step-scan FTIR modulation/demodulation technique. The changes in both the in-phase and quadrature spectra as a function of temperature reveal different responses for the various functional groups as a function of temperature. In particular, as the temperature is lowered, the dynamic responses of structurally different carbonyl groups (hydrogen-bonded, free, urethane, ester) are clearly differentiated. The changes in dynamic response are related to changes in the hydrogen-bonding interactions in this polymer as well as to distinction between different molecularlevel microenvironments.

Many practitioners and academics believe in a delayed issue effect (DIE); i.e. the longer an issue lingers in the system, the more effort it requires to resolve. This belief is often used to justify major investments in new development processes that promise to retire more issues sooner. This paper tests for the delayed issue effect in 171 software projects conducted around the world in the period from 2006â2014. To the best of our knowledge, this is the largest study yet published on this effect. We found no evidence for the delayed issue effect; i.e. the effort to resolve issues in a later phase was not consistently or substantially greater than when issues were resolved soon after their introduction. This paper documents the above study and explores reasons for this mismatch between this common rule of thumb and empirical data. In summary, DIE is not some constant across all projects. Rather, DIE might be an historical relic that occurs intermittently only in certa in kinds of projects. This is a significant result since it predicts that new development processes that promise to faster retire more issues will not have a guaranteed return on investment (depending on the context where applied), and that a long-held truth in software engineering should not be considered a global truism

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