Large Scale Structure of the Universe

Galaxies are not uniformly distributed in space. On large scales the Universe displays coherent structure, with galaxies residing in groups and clusters on scales of ~1-3 Mpc/h, which lie at the intersections of long filaments of galaxies that are >10 Mpc/h in length. Vast regions of relatively empty space, known as voids, contain very few galaxies and span the volume in between these structures. This observed large scale structure depends both on cosmological parameters and on the formation and evolution of galaxies. Using the two-point correlation function, one can trace the dependence of large scale structure on galaxy properties such as luminosity, color, stellar mass, and track its evolution with redshift. Comparison of the observed galaxy clustering signatures with dark matter simulations allows one to model and understand the clustering of galaxies and their formation and evolution within their parent dark matter halos. Clustering measurements can determine the parent dark matter halo mass of a given galaxy population, connect observed galaxy populations at different epochs, and constrain cosmological parameters and galaxy evolution models. This chapter describes the methods used to measure the two-point correlation function in both redshift and real space, presents the current results of how the clustering amplitude depends on various galaxy properties, and discusses quantitative measurements of the structures of voids and filaments. The interpretation of these results with current theoretical models is also presented.Comment: Invited contribution to be published in Vol. 8 of book "Planets, Stars, and Stellar Systems", Springer, series editor T. D. Oswalt, volume editor W. C. Keel, v2 includes additional references, updated to match published versio

Impaired work functioning due to common mental disorders in nurses and allied health professionals: the Nurses Work Functioning Questionnaire

Common mental disorders (CMD) negatively affect work functioning. In the health service sector not only the prevalence of CMDs is high, but work functioning problems are associated with a risk of serious consequences for patients and healthcare providers. If work functioning problems due to CMDs are detected early, timely help can be provided. Therefore, the aim of this study is to develop a detection questionnaire for impaired work functioning due to CMDs in nurses and allied health professionals working in hospitals. First, an item pool was developed by a systematic literature study and five focus group interviews with employees and experts. To evaluate the content validity, additional interviews were held. Second, a cross-sectional assessment of the item pool in 314 nurses and allied health professionals was used for item selection and for identification and corroboration of subscales by explorative and confirmatory factor analysis. The study results in the Nurses Work Functioning Questionnaire (NWFQ), a 50-item self-report questionnaire consisting of seven subscales: cognitive aspects of task execution, impaired decision making, causing incidents at work, avoidance behavior, conflicts and irritations with colleagues, impaired contact with patients and their family, and lack of energy and motivation. The questionnaire has a proven high content validity. All subscales have good or acceptable internal consistency. The Nurses Work Functioning Questionnaire gives insight into precise and concrete aspects of impaired work functioning of nurses and allied health professionals. The scores can be used as a starting point for purposeful intervention

Retained Surgical Items and Minimally Invasive Surgery

A retained surgical item is a surgical patient safety problem. Early reports have focused on the epidemiology of retained-item cases and the identification of patient risk factors for retention. We now know that retention has very little to do with patient characteristics and everything to do with operating room culture. It is a perception that minimally invasive procedures are safer with regard to the risk of retention. Minimally invasive surgery is still an operation where an incision is made and surgical tools are placed inside of patients, so these cases are not immune to the problem of inadvertent retention. Retained surgical items occur because of problems with multi-stakeholder operating room practices and problems in communication. The prevention of retained surgical items will therefore require practice change, knowledge, and shared information between all perioperative personnel

Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae)

The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitro-quinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 μg/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV ≤ 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies

Gamma Power Is Phase-Locked to Posterior Alpha Activity

Neuronal oscillations in various frequency bands have been reported in numerous studies in both humans and animals. While it is obvious that these oscillations play an important role in cognitive processing, it remains unclear how oscillations in various frequency bands interact. In this study we have investigated phase to power locking in MEG activity of healthy human subjects at rest with their eyes closed. To examine cross-frequency coupling, we have computed coherence between the time course of the power in a given frequency band and the signal itself within every channel. The time-course of the power was calculated using a sliding tapered time window followed by a Fourier transform. Our findings show that high-frequency gamma power (30–70 Hz) is phase-locked to alpha oscillations (8–13 Hz) in the ongoing MEG signals. The topography of the coupling was similar to the topography of the alpha power and was strongest over occipital areas. Interestingly, gamma activity per se was not evident in the power spectra and only became detectable when studied in relation to the alpha phase. Intracranial data from an epileptic subject confirmed these findings albeit there was slowing in both the alpha and gamma band. A tentative explanation for this phenomenon is that the visual system is inhibited during most of the alpha cycle whereas a burst of gamma activity at a specific alpha phase (e.g. at troughs) reflects a window of excitability

Nucleolar Association and Transcriptional Inhibition through 5S rDNA in Mammals

Changes in the spatial positioning of genes within the mammalian nucleus have been associated with transcriptional differences and thus have been hypothesized as a mode of regulation. In particular, the localization of genes to the nuclear and nucleolar peripheries is associated with transcriptional repression. However, the mechanistic basis, including the pertinent cis- elements, for such associations remains largely unknown. Here, we provide evidence that demonstrates a 119 bp 5S rDNA can influence nucleolar association in mammals. We found that integration of transgenes with 5S rDNA significantly increases the association of the host region with the nucleolus, and their degree of association correlates strongly with repression of a linked reporter gene. We further show that this mechanism may be functional in endogenous contexts: pseudogenes derived from 5S rDNA show biased conservation of their internal transcription factor binding sites and, in some cases, are frequently associated with the nucleolus. These results demonstrate that 5S rDNA sequence can significantly contribute to the positioning of a locus and suggest a novel, endogenous mechanism for nuclear organization in mammals