Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Principles of survey research part 4: questionnaire evaluation

Abstract: This article discusses how to avoid biased questions in survey instruments, how to motivate people to complete instruments and how to evaluate instruments. In the context of survey evaluation, we discuss how to assess survey reliability i.e. how reproducible a survey's data is and survey validity i.e. how well a survey instrument measures what it sets out to measure.

Non-standard s process in low metallicity massive rotating stars

Abstract: Context. Rotation is known to have a strong impact on the nucleosynthesis of light elements in massive stars, mainly by inducing mixing in radiative zones. In particular, rotation boosts the primary nitrogen production, and models of rotating stars are able to reproduce the nitrogen observed in low-metallicity halo stars. Aims. Here we present the first grid of stellar models for rotating massive stars at low metallicity, where a full s-process network is used to study the impact of rotation-induced mixing on the neutron capture nucleosynthesis of heavy elements. Methods. We used the Geneva stellar evolution code that includes an enlarged reaction network with nuclear species up to bismuth to calculate 25 M ⊙ models at three different metallicities (Z = 10-3 ,10-5 , and 10-7 ) and with different initial rotation rates. Results. First, we confirm that rotation-induced mixing (shear) between the convective H-shell and He-core leads to a large production of primary 22 Ne (0.1 to 1% in mass fraction), which is the main neutron source for the s-process in massive stars. Therefore rotation boosts the s-process in massive stars at all metallicities. Second, the neutron-to-seed ratio increases with decreasing Z in models including rotation, which leads to the complete consumption of all iron seeds at metallicities below Z = 10-3 by the end of core He-burning. Thus at low Z , the iron seeds are the main limitation for this boosted s-process. Third, as the metallicity decreases, the production of elements up to the Ba peak increases at the expense of the elements of the Sr peak. We studied the impact of the initial rotation rate and of the highly uncertain 17 O(α,γ ) rate (which strongly affects the strength of 16 O as a neutron poison) on our results. This study shows that rotating models can produce significant amounts of elements up to Ba over a wide range of Z , which has important consequences for our understanding of the formation of these elements in low-metallicity environments like the halo of our galaxy and globular clusters. Fourth, compared to the He-core, the primary 22 Ne production induced by rotation in the He-shell is even higher (greater than 1% in mass fraction at all metallicities), which could open the door for an explosive neutron capture nucleosynthesis in the He-shell, with a primary neutron source.

The “Ticktock” of Our Internal Clock Direct Brain Evidence of Subjective Accents in Isochronous Sequences

Abstract: The phenomenon commonly known as subjective accenting refers to the fact that identical sound events within purely isochronous sequences are perceived as unequal. Although subjective accenting has been extensively explored using behavioral methods, no physiological evidence has ever been provided for it. In the present study, we tested the notion that these perceived irregularities are related to the dynamic deployment of attention. We disrupted listeners' expectancies in different positions of auditory equitone sequences and measured their responses through brain event-related potentials (ERPs). Significant differences in a late parietal (P3-like) ERP component were found between the responses elicited on odd-numbered versus even-numbered positions, suggesting that a default binary metric structure was perceived. Our findings indicate that this phenomenon has a rather cognitive, attention-dependent origin, partly affected by musical expertise.