Testing Screened Fifth Forces: From Cosmological to Solar System Scales

In this thesis we present three different approaches to testing screened fifth forces on scales ranging from the largest structures in the Universe to the Solar System. Firstly, we study the cosmic matter bispectrum in a cubic Galileon model and find that the shape dependence of Vainshtein screening leaves a very intuitive signature on the bispectrum. A numerical analysis with hi_class demonstrates that the strength of the signal relative to the signal from general relativity alone is proportional to the fractional energy density of the Galileon at redshift z=0 and evolves like a^(3/2). Since this shape dependence is very characteristic of Vainshtein screening, it may prove useful for differentiating between different models of fifth forces with data from future galaxy surveys. Second, we determine the conditions under which the solar-system constraints on the time evolution of the gravitational constant may be extrapolated to cosmological scales. If these conditions are met for a specific fifth force model, strong constraints on the evolution of the cosmological gravitational constant are placed, which prohibit self acceleration as an explanation for the accelerated expansion of the late Universe. We find that the conditions hold for the most common screening mechanisms unless the screening is extreme in the sense that even the largest and least dense observable objects in the Universe are screened, in which case violations of the equivalence principle may prohibit the extrapolation of solar-system constraints to cosmological scales. Lastly, we derive an analytic solution for the Galileon field in a hierarchical two-body system, where one mass greatly exceeds the other mass. We observe that the field around the smaller mass becomes elliptical outside the `Vainshtein boundary'. We estimate that this ellipticity only has a small effect in the sun-earth system, but could be at the ~4% level on intergalactic scales and thus influence the dynamics of field galaxies moving through the field of a distant galaxy cluster in a manner significantly different from the predictions of pure general relativity

Distribution of Fish Species in Cedar Lake

With over 13,000 described species of freshwater fishes, diversity within aquatic systems can vary extensively. At the local scale small changes in the diversity of fish species within an ecosystem will modify processes within the ecosystem such as community decomposition and metabolism. Recent analyses indicate that actual species diversity within small, shallow ponds may be higher than previously thought. Fish species distribution will differ based on location within the aquatic system relative to the species’ position in the trophic web. We will measure both quantitative and qualitative differences among species at different locations within of Cedar Lake, expecting to find a decrease in both species diversity and total number of fish as the depth increases. We will count the number of fish species and the total number of fish at each depth and use t-test analysis to determine if depth influences fish diversity

Do more specific plans help you lose weight? Examining the relationship between plan specificity, weight loss goals, and plan content in the context of a weight management programme

Objectives: The conditions under which planning for behaviour change is most effective are not fully understood. In the context of a weight management intervention, we examined the interrelationship between plan specificity, type of behaviour planned (diet vs. exercise) and weight loss goals.  Design: Prospective design and content analysis of plans formed by participants of a 10-week weight management programme.  Methods: Participants (n=239) formulated two plans, for dietary and exercise behaviours respectively. Plans were rated for specificity by examining the number of plan components. Weight loss goals were assessed by asking how much weight participants intend to lose. Weight was measured objectively each of the 10 weeks. Changes in BMI over time and the interactions between plan specificity, and weight loss goals, for all plans and separately for diet and exercise, were estimated using linear mixed models.  Results: Plan specificity was unrelated to weight loss, but interacted with weight loss goals in predicting linear change in BMI (t= -2.48): More specific plans were associated with higher decreases in weight in participants with high weight loss goals. Separate interaction tests for plans formulated for diet and exercise change showed that more specific dietary plans, but not exercise ones, were associated with higher decreases in weight in participants with high weight loss goals (t= -2.21).  Conclusions: Within a population that is highly motivated to lose weight, the combination of high weight loss goals and formulating detailed plans for changing dietary behaviours may be most effective in supporting weight loss

Testing Screened Fifth Forces: From Cosmological to Solar System Scales

In this thesis we present three different approaches to testing screened fifth forces on scales ranging from the largest structures in the Universe to the Solar System. Firstly, we study the cosmic matter bispectrum in a cubic Galileon model and find that the shape dependence of Vainshtein screening leaves a very intuitive signature on the bispectrum. A numerical analysis with hi_class demonstrates that the strength of the signal relative to the signal from general relativity alone is proportional to the fractional energy density of the Galileon at redshift z=0 and evolves like a^(3/2). Since this shape dependence is very characteristic of Vainshtein screening, it may prove useful for differentiating between different models of fifth forces with data from future galaxy surveys. Second, we determine the conditions under which the solar-system constraints on the time evolution of the gravitational constant may be extrapolated to cosmological scales. If these conditions are met for a specific fifth force model, strong constraints on the evolution of the cosmological gravitational constant are placed, which prohibit self acceleration as an explanation for the accelerated expansion of the late Universe. We find that the conditions hold for the most common screening mechanisms unless the screening is extreme in the sense that even the largest and least dense observable objects in the Universe are screened, in which case violations of the equivalence principle may prohibit the extrapolation of solar-system constraints to cosmological scales. Lastly, we derive an analytic solution for the Galileon field in a hierarchical two-body system, where one mass greatly exceeds the other mass. We observe that the field around the smaller mass becomes elliptical outside the `Vainshtein boundary'. We estimate that this ellipticity only has a small effect in the sun-earth system, but could be at the ~4% level on intergalactic scales and thus influence the dynamics of field galaxies moving through the field of a distant galaxy cluster in a manner significantly different from the predictions of pure general relativity

Prospectus, September 15, 2010

WHAT A COMMUNITY COLLEGE HAS TO OFFER; Zombies lumber into university curriculum; Chuck Shepherd’s News of the Weird; The greatness of movie soundtracks; Welcome week at Parkland: How it all went down; Socially conscious shoppers look for the fair-trade label, but what does it mean?; A fate worse than death; Fidel Castro, former Cuban president turned Internet junkie; Parkland to take trip to Vienna; Caution children at play: How students can keep their ldds safe at Parkland; Super-sized is the new normal; Prospectus Pick: Catcher in the Rye by J.D. Salinger; Go tech-free for 24 hours and say hello to loved ones; Building from success: Parkland aims high for fall athletics; Parkland Art Gallery Art & Design Faculty Exhibitionhttps://spark.parkland.edu/prospectus_2010/1022/thumbnail.jp

A Netrin-3 Like Protein is Secreted from \u3ci\u3eTetrahymena thermophila\u3c/i\u3e

Netrin proteins are a family of laminin-related secreted proteins that provide signals for axonal growth and cell migration during vertebrate development. Netrin homologs are expressed throughout the animal kingdom; however, some animals do not express a homolog of any known netrin receptors. We have previously found that the ciliated protozoan, Tetrahymena thermophila, responds to netrin-1 peptide by showing avoidance behavior. In addition, Tetrahymena secrete a protein that is immunologically similar to netrin-1 as detected by ELISA. Since netrin-3, like netrin-1, is a guidance molecule for axons and overlaps signaling pathways with netrin-1 in vertebrates, we hypothesized that netrin-3 may also act as a chemorepellent in Tetrahymena. While behavioral assays did not confirm this hypothesis, growth assays indicate that netrin-3 peptide inhibits cell division in Tetrahymena. In addition, ELISA and Western blots indicate that a netrin-3 like protein of approximately 48 kDa is secreted from Tetrahymena. Immunolocalization of this protein within the cell shows that it appears in widely distributed throughout the cell, and co-localizes with the netrin-1 like protein. Using ER tracker™, we found that some of the netrin-3-like protein co-localizes with the endoplasmic reticulum, as might be expected for a secreted protein. Further experimentation is necessary to determine the mechanism by which netrin-3 peptide inhibits growth in Tetrahymena

Inflammatory Aetiology of Human Myometrial Activation Tested Using Directed Graphs

There are three main hypotheses for the activation of the human uterus at labour: functional progesterone withdrawal, inflammatory stimulation, and oxytocin receptor activation. To test these alternatives we have taken information and data from the literature to develop causal pathway models for the activation of human myometrium. The data provided quantitative RT-PCR results on key genes from samples taken before and during labour. Principal component analysis showed that pre-labour samples form a homogenous group compared to those during labour. We therefore modelled the alternative causal pathways in non-labouring samples using directed graphs and statistically compared the likelihood of the different models using structural equations and D-separation approaches. Using the computer program LISREL, inflammatory activation as a primary event was highly consistent with the data (p = 0.925), progesterone withdrawal, as a primary event, is plausible (p = 0.499), yet comparatively unlikely, oxytocin receptor mediated initiation is less compatible with the data (p = 0.091). DGraph, a software program that creates directed graphs, produced similar results (p = 0.684, p = 0.280, and p = 0.04, respectively). This outcome supports an inflammatory aetiology for human labour. Our results demonstrate the value of directed graphs in determining the likelihood of causal relationships in biology in situations where experiments are not possible

Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS): a mixed-methods study to inform trial design

Background: Smoking in pregnancy and/or not breastfeeding have considerable negative health outcomes for mother and baby. Aim: To understand incentive mechanisms of action for smoking cessation in pregnancy and breastfeeding, develop a taxonomy and identify promising, acceptable and feasible interventions to inform trial design. Design: Evidence syntheses, primary qualitative survey, and discrete choice experiment (DCE) research using multidisciplinary, mixed methods. Two mother-and-baby groups in disadvantaged areas collaborated throughout. Setting: UK. Participants: The qualitative study included 88 pregnant women/recent mothers/partners, 53 service providers, 24 experts/decision-makers and 63 conference attendees. The surveys included 1144 members of the general public and 497 health professionals. The DCE study included 320 women with a history of smoking. Methods: (1) Evidence syntheses: incentive effectiveness (including meta-analysis and effect size estimates), delivery processes, barriers to and facilitators of smoking cessation in pregnancy and/or breastfeeding, scoping review of incentives for lifestyle behaviours; (2) qualitative research: grounded theory to understand incentive mechanisms of action and a framework approach for trial design; (3) survey: multivariable ordered logit models; (4) DCE: conditional logit regression and the log-likelihood ratio test. Results: Out of 1469 smoking cessation and 5408 breastfeeding multicomponent studies identified, 23 smoking cessation and 19 breastfeeding studies were included in the review. Vouchers contingent on biochemically proven smoking cessation in pregnancy were effective, with a relative risk of 2.58 (95% confidence interval 1.63 to 4.07) compared with non-contingent incentives for participation (four studies, 344 participants). Effects continued until 3 months post partum. Inconclusive effects were found for breastfeeding incentives compared with no/smaller incentives (13 studies) but provider commitment contracts for breastfeeding show promise. Intervention intensity is a possible confounder. The acceptability of seven promising incentives was mixed. Women (for vouchers) and those with a lower level of education (except for breastfeeding incentives) were more likely to disagree. Those aged ≤ 44 years and ethnic minority groups were more likely to agree. Agreement was greatest for a free breast pump and least for vouchers for breastfeeding. Universal incentives were preferred to those targeting low-income women. Initial daily text/telephone support, a quitting pal, vouchers for > £20.00 per month and values up to £80.00 increase the likelihood of smoking cessation. Doctors disagreed with provider incentives. A ‘ladder’ logic model emerged through data synthesis and had face validity with service users. It combined an incentive typology and behaviour change taxonomy. Autonomy and well-being matter. Personal difficulties, emotions, socialising and attitudes of others are challenges to climbing a metaphorical ‘ladder’ towards smoking cessation and breastfeeding. Incentive interventions provide opportunity ‘rungs’ to help, including regular skilled flexible support, a pal, setting goals, monitoring and outcome verification. Individually tailored and non-judgemental continuity of care can bolster women’s capabilities to succeed. Rigid, prescriptive interventions placing the onus on women to behave ‘healthily’ risk them feeling pressurised and failing. To avoid ‘losing face’, women may disengage. Limitations: Included studies were heterogeneous and of variable quality, limiting the assessment of incentive effectiveness. No cost-effectiveness data were reported. In surveys, selection bias and confounding are possible. The validity and utility of the ladder logic model requires evaluation with more diverse samples of the target population. Conclusions: Incentives provided with other tailored components show promise but reach is a concern. Formal evaluation is recommended. Collaborative service-user involvement is importan

Global genetic diversity of var2csa in Plasmodium falciparum with implications for malaria in pregnancy and vaccine development

Malaria infection during pregnancy, caused by the sequestering of Plasmodium falciparum parasites in the placenta, leads to high infant mortality and maternal morbidity. The parasite-placenta adherence mechanism is mediated by the VAR2CSA protein, a target for natural occurring immunity. Currently, vaccine development is based on its ID1-DBL2Xb domain however little is known about the global genetic diversity of the encoding var2csa gene, which could influence vaccine efficacy. In a comprehensive analysis of the var2csa gene in >2,000 P. falciparum field isolates across 23 countries, we found that var2csa is duplicated in high prevalence (>25%), African and Oceanian populations harbour a much higher diversity than other regions, and that insertions/deletions are abundant leading to an underestimation of the diversity of the locus. Further, ID1-DBL2Xb haplotypes associated with adverse birth outcomes are present globally, and African-specific haplotypes exist, which should be incorporated into vaccine design