Gravity Waves from a Cosmological Phase Transition: Gauge Artifacts and Daisy Resummations

The finite-temperature effective potential customarily employed to describe the physics of cosmological phase transitions often relies on specific gauge choices, and is manifestly not gauge-invariant at finite order in its perturbative expansion. As a result, quantities relevant for the calculation of the spectrum of stochastic gravity waves resulting from bubble collisions in first-order phase transitions are also not gauge-invariant. We assess the quantitative impact of this gauge-dependence on key quantities entering predictions for gravity waves from first order cosmological phase transitions. We resort to a simple abelian Higgs model, and discuss the case of R_xi gauges. By comparing with results obtained using a gauge-invariant Hamiltonian formalism, we show that the choice of gauge can have a dramatic effect on theoretical predictions for the normalization and shape of the expected gravity wave spectrum. We also analyze the impact of resumming higher-order contributions as needed to maintain the validity of the perturbative expansion, and show that doing so can suppress the amplitude of the spectrum by an order of magnitude or more. We comment on open issues and possible strategies for carrying out "daisy resummed" gauge invariant computations in non-Abelian models for which a gauge-invariant Hamiltonian formalism is not presently available.Comment: 25 pages, 10 figure

Intellectual engagement and cognitive ability in later life (the "use it or lose it" conjecture) : Longitudinal, prospective study

Data sharing: All data are available by application to the Aberdeen Birth Cohort steering group (https://www.abdn.ac.uk/birth-cohorts/1921/for-researchers/).Peer reviewedPublisher PD

Cell Cycle–Specified Fluctuation of Nucleosome Occupancy at Gene Promoters

The packaging of DNA into nucleosomes influences the accessibility of underlying regulatory information. Nucleosome occupancy and positioning are best characterized in the budding yeast Saccharomyces cerevisiae, albeit in asynchronous cell populations or on individual promoters such as PHO5 and GAL1–10. Using FAIRE (formaldehyde-assisted isolation of regulatory elements) and whole-genome microarrays, we examined changes in nucleosome occupancy throughout the mitotic cell cycle in synchronized populations of S. cerevisiae. Perhaps surprisingly, nucleosome occupancy did not exhibit large, global variation between cell cycle phases. However, nucleosome occupancy at the promoters of cell cycle–regulated genes was reduced specifically at the cell cycle phase in which that gene exhibited peak expression, with the notable exception of S-phase genes. We present data that establish FAIRE as a high-throughput method for assaying nucleosome occupancy. For the first time in any system, nucleosome occupancy was mapped genome-wide throughout the cell cycle. Fluctuation of nucleosome occupancy at promoters of most cell cycle–regulated genes provides independent evidence that periodic expression of these genes is controlled mainly at the level of transcription. The promoters of G(2)/M genes are distinguished from other cell cycle promoters by an unusually low baseline nucleosome occupancy throughout the cell cycle. This observation, coupled with the maintenance throughout the cell cycle of the stereotypic nucleosome occupancy states between coding and non-coding loci, suggests that the largest component of variation in nucleosome occupancy is “hard wired,” perhaps at the level of DNA sequence

Environmental justice: An analysis of superfund sites

In this study we investigate the spatial relationship between Superfund sites and the racial, ethnic, and economic characteristics of the areas surrounding those sites in the state of Florida. Unlike many previous environmental justice studies, we examine census tracts rather than larger aggregates such as counties or zip codes. We also look at the problem of environmental injustice longitudinally by analyzing Census data from 1970, I980, and 1990. Such an analysis not only allows us to detect potential environmental inequality, but also to postulate on the nature and origins of this injustice. Overall, our findings indicate that Blacks and Hispanics are more likely to live near Superfund hazardous waste sites, but income and poverty indicators do not predict the location of sites. The spatial association between race, ethnicity, and Superfund sites is increasing over time, leading us to conclude that the likely cause of much of the recent environmental injustice uncovered in our results stems from indirect, rather than direct, forms of discrimination. © COPYRIGHT 1998 University of California Press Environmental justice (EJ) researchers have focused much of their research on the spatial relationship between race, ethnicity, economics and hazardous waste facilities.(1) However, the study of EJ encompasses more than the analysis of the placement of active waste facilities in minority and poor areas (Bullard 1996). It is also concerned with the social and economic processes that shape racial, ethnic, and economic demographic patterns around existing hazardous waste sites. For this reason, we have chosen to examine the issue of environmental justice by looking at the spatial distribution of Superfund sites. Such an endeavor contributes to the body of EJ research in three ways. First, our analysis helps shed some light on the recent debate concerning the existence of environmental injustice. This debate is most often framed in terms of the presence or absence of a statistical association between race, ethnicity, income, and hazardous waste. For instance, several studies provide evidence that demonstrates that nonWhites and the poor are more likely to live near hazardous waste than are Whites and the more affluent (e.

Listening to self-chosen music regulates induced negative affect for both younger and older adults

The current study evaluated the efficacy of self-chosen music listening for the function of affect regulation comparing effects in younger and older adults. Forty younger (18-30 years, M = 19.75, SD = 2.57, 14 males) and forty older (60-81 years, M = 68.48, SD = 6.07, 21 males) adults visited the laboratory and were randomised to either the intervention (10 minutes of listening to self-chosen music) or the active control condition (10 minutes of listening to an experimenter-chosen radio documentary). Negative affect (NA) was induced in all participants using a speech preparation and mental arithmetic task, followed by the intervention/control condition. Measures of self-reported affect were taken at baseline, post-induction and post-intervention. Controlling for baseline affect and reactivity to the NA induction, in comparison with the active control group the music listening group demonstrated greater reduction in NA. Supporting developmental theories of positive ageing, analyses also found significant main effects for age, with older adults experiencing greater reduction of NA than younger adults, regardless of condition. Results of the current study provide preliminary insights into the effects of self-chosen music on induced NA, however, additional experimental control conditions comparing self-chosen and experimenter-chosen music with self-chosen and experimenter-chosen active controls are needed to fully understand music listening effects for affect regulation