The Impact of Inter-Bed Cohesion on Fold-Related Fracture Development, Stillwell Anticline, West Texas (USA)

The interpretation of fracture networks in contractional folds is challenging due to the range of factors that control fracture formation. We use outcrop-based analysis of fractures in plan-view pavements and in a 9-bed cross-sectional exposure to evaluate the fracture system within Cretaceous limestone layers of a Laramide fold in west Texas, the Stillwell anticline. Opening-mode extension fractures (veins) at high angles to bedding dominate the fracture population, although shear fractures and faults cut bedding at low angles within the forelimb. Analysis of extension fractures reveals NW-striking axial parallel and NE-striking axial-perpendicular fracture sets interpreted to have formed during contractional folding, a third N-striking fracture set formed during subsequent Basin and Range extension, and a fourth ESE-striking fracture formed due to unloading during exhumation. Fracture fill textures suggest that many fracture apertures increased during exhumation. The relative abundances of the four fracture sets and the intensity of each set vary from bed to bed in cross section. Because beds display no significant differences in mechanical strength and there is no correlation between bed thickness and fracture intensity, we attribute this bed-to-bed variability to differences in cohesion between beds. Bed decoupling, when combined with low extensional

An evaluation of the replicate pool method: quick estimation of genome-wide linkage peak p -values

The calculation of empirical p -values for genome-wide non-parametric linkage tests continues to present significant computational challenges for many complex disease mapping studies. The gold standard approach is to use gene dropping to simulate null genome scans. Unfortunately, this approach is too computationally expensive for many data sets of interest. An alternative, more efficient method for sampling null genome scans is to pre-calculate pools of family-specific statistics and then resample from these replicate pools to generate “pseudo-replicate” genome scans. In this study, we use simulations to explore properties of the replicate pool p -value estimator [pcirc] RP and show that it provides an excellent approximation to the traditional gene-dropping estimator for significantly less computational effort. While the computational efficiency of the replicate pool estimator is noticeable in almost all data sets, by applying the replicate pool method to several previously characterized data sets we show that savings in computational effort can be especially significant (on the order of 10,000-fold or more) when one or more large families are analyzed. We also estimate replicate pool p -values for the schizophrenia data described by Abecasis et al. and show that [pcirc] RP closely approximates gene-drop p -values for all linkage peaks reported for this study. Lastly, we expand upon Song et al.'s previous work by deriving a conservative estimator of the variance for [pcirc] RP that can easily be computed in practical settings.We have implemented the replicate pool method along with our variance estimator in a new program called Pseudo, which is the first widely available automated implementation of the replicate pool method. Genet . Epidemiol . 30, 2006. © 2006 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50657/1/20147_ftp.pd

Increased susceptibility to repeated freeze-thaw cycles in Escherichia coli following long-term evolution in a benign environment

BACKGROUND: In order to study the dynamics of evolutionary change, 12 populations of E. coli B were serially propagated for 20,000 generations in minimal glucose medium at constant 37°C. Correlated changes in various other traits have been previously associated with the improvement in competitive fitness in the selective environment. This study examines whether these evolved lines changed in their ability to tolerate the stresses of prolonged freezing and repeated freeze-thaw cycles during adaptation to a benign environment. RESULTS: All 12 lines that evolved in the benign environment for 20,000 generations are more sensitive to freeze-thaw cycles than their ancestor. The evolved lines have an average mortality rate of 54% per daily cycle, compared to the ancestral rate of 34%. By contrast, there was no significant difference between the evolved lines and their ancestor in mortality during prolonged freezing. There was also some variability among the evolved lines in susceptibility to repeated freeze-thaw cycles. Those lines that had evolved higher competitive fitness in the minimal glucose medium at 37°C also had higher mortality during freeze-thaw cycles. This variability was not associated, however, with differences among lines in DNA repair functionality and mutability. CONCLUSION: The consistency of the evolutionary declines in freeze-thaw tolerance, the correlation between fitness in glucose medium at 37°C and mortality during freeze-thaw cycles, and the absence of greater declines in freeze-thaw survival among the hypermutable lines all indicate a trade-off between performance in minimal glucose medium at 37°C and the capacity to tolerate this stress. Analyses of the mutations that enhance fitness at 37°C may shed light on the physiological basis of this trade-off

An Environmental Science and Engineering Framework for Combating Antimicrobial Resistance

On June 20, 2017, members of the environmental engineering and science (EES) community convened at the Association of Environmental Engineering and Science Professors (AEESP) Biennial Conference for a workshop on antimicrobial resistance. With over 80 registered participants, discussion groups focused on the following topics: risk assessment, monitoring, wastewater treatment, agricultural systems, and synergies. In this study, we summarize the consensus among the workshop participants regarding the role of the EES community in understanding and mitigating the spread of antibiotic resistance via environmental pathways. Environmental scientists and engineers offer a unique and interdisciplinary perspective and expertise needed for engaging with other disciplines such as medicine, agriculture, and public health to effectively address important knowledge gaps with respect to the linkages between human activities, impacts to the environment, and human health risks. Recommendations that propose priorities for research within the EES community, as well as areas where interdisciplinary perspectives are needed, are highlighted. In particular, risk modeling and assessment, monitoring, and mass balance modeling can aid in the identification of “hot spots” for antibiotic resistance evolution and dissemination, and can help identify effective targets for mitigation. Such information will be essential for the development of an informed and effective policy aimed at preserving and protecting the efficacy of antibiotics for future generations

Views on and experiences of electronic cigarettes: a qualitative study of women who are pregnant or have recently given birth.

Background Electronic cigarettes (ECs) are increasingly used for reducing or stopping smoking, with some studies showing positive outcomes. However, little is known about views on ECs during pregnancy or postpartum and previous studies have nearly all been conducted in the US and have methodological limitations, such as not distinguishing between smokers and ex/non-smokers. A greater understanding of this topic will help to inform both clinicians and EC interventions. We elicited views and experiences of ECs among UK pregnant or recently pregnant women. Methods We conducted semi-structured telephone interviews, using topic guides, with pregnant or recently pregnant women, who were current or recent ex-smokers. To ensure broad views of ECs were obtained, recruitment was from several geographical locations and via various avenues of recruitment. This included stop smoking services, antenatal and health visitor clinics, a pregnancy website and an informal network. Participants were 15 pregnant and 15 postpartum women, including nine current EC users, 11 ex-users, and 10 never-users. Five women who were interviewed in pregnancy were later interviewed in postpartum to explore if their views had changed. Audio data was transcribed verbatim and framework analysis was applied. Results Five main themes emerged: motivations for use (e.g., for stopping or reducing smoking), social stigma (e.g., avoiding use in public, preferring ‘discrete’ NRT), using the EC (e.g., mostly used at home); consumer aspects (e.g., limited advice available), and harm perceptions (e.g., viewed as less harmful than smoking; concerns about safety and addiction). Conclusions ECs were viewed positively by some pregnant and postpartum women and seen as less harmful than smoking and useful as aids for reducing and stopping smoking. However, due to perceived social stigma, some women feel uncomfortable using ECs in public, especially during pregnancy, and had concerns about safety and nicotine dependence. Health professionals and designers of EC interventions need to provide women with up-to-date and consistent information and advice about safety and dependence, as well as considering the influence of social stigma

Gene set of nuclear-encoded mitochondrial regulators is enriched for common inherited variation in obesity

There are hints of an altered mitochondrial function in obesity. Nuclear-encoded genes are relevant for mitochondrial function (3 gene sets of known relevant pathways: (1) 16 nuclear regulators of mitochondrial genes, (2) 91 genes for oxidative phosphorylation and (3) 966 nuclear-encoded mitochondrial genes). Gene set enrichment analysis (GSEA) showed no association with type 2 diabetes mellitus in these gene sets. Here we performed a GSEA for the same gene sets for obesity. Genome wide association study (GWAS) data from a case-control approach on 453 extremely obese children and adolescents and 435 lean adult controls were used for GSEA. For independent confirmation, we analyzed 705 obesity GWAS trios (extremely obese child and both biological parents) and a population-based GWAS sample (KORA F4, n = 1,743). A meta-analysis was performed on all three samples. In each sample, the distribution of significance levels between the respective gene set and those of all genes was compared using the leading-edge-fraction-comparison test (cut-offs between the 50(th) and 95(th) percentile of the set of all gene-wise corrected p-values) as implemented in the MAGENTA software. In the case-control sample, significant enrichment of associations with obesity was observed above the 50(th) percentile for the set of the 16 nuclear regulators of mitochondrial genes (p(GSEA,50) = 0.0103). This finding was not confirmed in the trios (p(GSEA,50) = 0.5991), but in KORA (p(GSEA,50) = 0.0398). The meta-analysis again indicated a trend for enrichment (p(MAGENTA,50) = 0.1052, p(MAGENTA,75) = 0.0251). The GSEA revealed that weak association signals for obesity might be enriched in the gene set of 16 nuclear regulators of mitochondrial genes