RESUMO
The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220-250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.
RESUMO
OBJECTIVE: Situational factors of prenatal screening have changed in recent decades. To explore the effect of a changing context on women's decision making, differences and similarities in the decision-making process of pregnant women regarding prenatal screening for fetal aneuploidy between two periods in time were studied. DESIGN: A qualitative comparison was made between a dataset of 22 semi-structured interviews with pregnant women from 2003 and a newly collected dataset with 19 semi-structured interviews from 2016. FINDINGS: Overall, women reported similar considerations in their decision-making process in 2003 and 2016, suggesting that decision making has not essentially changed. In 2016, women were still making a deliberate decision, however for some women costs and societal views as to what is acceptable did appear to impact the decision-making process. Moreover, new screening possibilities (e.g. improved test characteristics and including more conditions to be screened) seemed to impact the decision outcome. CONCLUSIONS: Since most women based their decisions mainly on their personal values and personal experiences rather than on situational factors, the results suggest that the changing context with regard to prenatal screening had no major effect on women's decision making. It therefore seems unlikely that future changes in the field of prenatal screening will drastically change the decision-making process of pregnant women as long as informed and deliberate decision making is safeguarded.
