Discreteness and entropic fluctuations in GREM-like systems

Within generalized random energy models, we study the effects of energy discreteness and of entropy extensivity in the low temperature phase. At zero temperature, discreteness of the energy induces replica symmetry breaking, in contrast to the continuous case where the ground state is unique. However, when the ground state energy has an extensive entropy, the distribution of overlaps P(q) instead tends towards a single delta function in the large volume limit. Considering now the whole frozen phase, we find that P(q) varies continuously with temperature, and that state-to-state fluctuations of entropy wash out the differences between the discrete and continuous energy models.Comment: 7 pages, 3 figure, 2 figures are added, the volume changes from 4 pages to 7 page

Patterns of 6-mercaptopurine and azathioprine maintenance therapy among a cohort of commercially insured individuals diagnosed with Crohn's disease in the United States

Background and aims: Thiopurines, including 6-mercaptopurine (6-MP) and azathioprine (AZA), are the mainstay of maintenance therapy for Crohn's disease (CD). However, studies examining their effectiveness in routine practice among diverse patient populations are lacking. Among a cohort of new users of 6MP/AZA, we described treatment patterns and changes in subsequent therapy. Methods: Using the Truven Health Analytics databases, we identified all individuals diagnosed with CD and initiating 6-MP/AZA monotherapy from 2001-2008 (n=3,657). We estimated the proportion of CD patients remaining on 6-MP/AZA monotherapy, using Kaplan-Meier methods, and identified predictors of treatment noncontinuation, using multivariable Cox regression. Among the "noncontinuers," we described subsequent patterns of maintenance therapy and summarized the diagnosis and procedure codes and prescription drug claims preceding treatment discontinuation. Results: The 1-year 6-MP/AZA treatment continuation rate was 42%. Children (age ?18 years) and individuals with no prior anti-tumor necrosis factor (TNF) use were more likely to continue 6-MP/AZA, while those dispensed more (>4) outpatient prescriptions for any drug before initiation of 6-MP/AZA were less likely to continue maintenance treatment. Overall, 1,128 (39%) and 105 (4%) individuals experienced a clinical event potentially indicating active disease or 6-MP/AZA-intolerance prior to discontinuation, respectively. Most patients discontinued therapy; among the remaining patients who failed to continue 6-MP/AZA, most augmented with an anti-TNF. Conclusion: Most patients initiating 6-MP/AZA monotherapy did not continue beyond 1 year. In contrast to trial evidence showing 1-year remission rates of 40%-80%, this study observed a lower effectiveness of 6-MP/AZA treatment, possibly due to differences in disease severity, patient demographics, comorbidity, adherence, and health care utilization

Young people's beliefs about the risk of bowel cancer and its link with physical activity.

OBJECTIVES: The primary objective was to explore young people's risk appraisals of bowel cancer, including whether they had a coherent understanding of the protective effects of physical activity (PA). A secondary objective was to examine whether the illness risk representations (IRRs) framework could be used to understand beliefs underlying bowel cancer risk appraisals. DESIGN: Qualitative. METHODS: Framework analysis of semi-structured interviews with 19 people aged 14-17 years. RESULTS: Participants judged their risk of getting bowel cancer as low. This was based on a lack of family history of cancer and their current lifestyle behaviours, which were viewed as having a protective effect, or because they planned on making change to their lifestyle in the future when disease risk became more relevant. Participants were not aware of, and struggled to understand, the link between PA and bowel cancer. They also lacked knowledge of the effects of, or treatments for, bowel cancer. Beliefs underlying judgements about the risk of bowel cancer fitted the IRR framework reasonably well. CONCLUSIONS: The present research suggests that interventions designed to increase PA with a view to reducing the risk of bowel cancer should aim to make the future risk of bowel cancer feel more tangible, help young people to understand the full range of consequences, explain how and why preventative behaviours such as PA are effective in reducing risk, and emphasize that the typical late presentation of symptoms, and therefore investigation by health care services, reduces treatability

Circular orbits of corotating binary black holes: comparison between analytical and numerical results

We compare recent numerical results, obtained within a ``helical Killing vector'' (HKV) approach, on circular orbits of corotating binary black holes to the analytical predictions made by the effective one body (EOB) method (which has been recently extended to the case of spinning bodies). On the scale of the differences between the results obtained by different numerical methods, we find good agreement between numerical data and analytical predictions for several invariant functions describing the dynamical properties of circular orbits. This agreement is robust against the post-Newtonian accuracy used for the analytical estimates, as well as under choices of resummation method for the EOB ``effective potential'', and gets better as one uses a higher post-Newtonian accuracy. These findings open the way to a significant ``merging'' of analytical and numerical methods, i.e. to matching an EOB-based analytical description of the (early and late) inspiral, up to the beginning of the plunge, to a numerical description of the plunge and merger. We illustrate also the ``flexibility'' of the EOB approach, i.e. the possibility of determining some ``best fit'' values for the analytical parameters by comparison with numerical data.Comment: Minor revisions, accepted for publication in Phys. Rev. D, 19 pages, 6 figure

Collecting biospecimens from an internet-based prospective cohort study of inflammatory bowel disease (CCFA Partners): A feasibility study

Background: The Internet has successfully been used for patient-oriented survey research. Internet-based translational research may also be possible. Objective: Our aim was to study the feasibility of collecting biospecimens from CCFA Partners, an Internet-based inflammatory bowel disease (IBD) cohort. Methods: From August 20, 2013, to January 4, 2014, we randomly sampled 412 participants, plus 179 from a prior validation study, and invited them to contribute a biospecimen. Participants were randomized to type (blood, saliva), incentive (none, US $20, or US$50), and collection method for blood. The first 82 contributors were also invited to contribute stool. We used descriptive statistics and t tests for comparisons. Results: Of the 591 participants, 239 (40.4%) indicated interest and 171 (28.9%) contributed a biospecimen. Validation study participants were more likely to contribute than randomly selected participants (44% versus 23%, P<.001). The return rate for saliva was higher than blood collected by mobile phlebotomist and at doctors offices (38%, 31%, and 17% respectively, P<.001). For saliva, incentives were associated with higher return rates (43-44% versus 26%, P=.04); 61% contributed stool. Fourteen IBD-Associated single nucleotide polymorphisms were genotyped, and risk allele frequencies were comparable to other large IBD populations. Bacterial DNA was successfully extracted from stool samples and was of sufficient quality to permit quantitative polymerase chain reaction for total bacteria. Conclusions: Participants are willing to contribute and it is feasible to collect biospecimens from an Internet-based IBD cohort. Home saliva kits yielded the highest return rate, though mobile phlebotomy was also effective. All samples were sufficient for genetic testing. These data support the feasibility of developing a centralized collection of biospecimens from this cohort to facilitate IBD translational studies

Origin and Evolution of Saturn's Ring System

The origin and long-term evolution of Saturn's rings is still an unsolved problem in modern planetary science. In this chapter we review the current state of our knowledge on this long-standing question for the main rings (A, Cassini Division, B, C), the F Ring, and the diffuse rings (E and G). During the Voyager era, models of evolutionary processes affecting the rings on long time scales (erosion, viscous spreading, accretion, ballistic transport, etc.) had suggested that Saturn's rings are not older than 100 My. In addition, Saturn's large system of diffuse rings has been thought to be the result of material loss from one or more of Saturn's satellites. In the Cassini era, high spatial and spectral resolution data have allowed progress to be made on some of these questions. Discoveries such as the ''propellers'' in the A ring, the shape of ring-embedded moonlets, the clumps in the F Ring, and Enceladus' plume provide new constraints on evolutionary processes in Saturn's rings. At the same time, advances in numerical simulations over the last 20 years have opened the way to realistic models of the rings's fine scale structure, and progress in our understanding of the formation of the Solar System provides a better-defined historical context in which to understand ring formation. All these elements have important implications for the origin and long-term evolution of Saturn's rings. They strengthen the idea that Saturn's rings are very dynamical and rapidly evolving, while new arguments suggest that the rings could be older than previously believed, provided that they are regularly renewed. Key evolutionary processes, timescales and possible scenarios for the rings's origin are reviewed in the light of tComment: Chapter 17 of the book ''Saturn After Cassini-Huygens'' Saturn from Cassini-Huygens, Dougherty, M.K.; Esposito, L.W.; Krimigis, S.M. (Ed.) (2009) 537-57

Achieving synergy: Linking an internet-based inflammatory bowel disease cohort to a community-based inception cohort and multicentered cohort in inflammatory bowel disease

Background: Traditional cohort studies are important contributors to our understanding of inflammatory bowel diseases, but they are labor intensive and often do not focus on patient-reported outcomes. Internet-based studies provide new opportunities to study patient-reported outcomes and can be efficiently implemented and scaled. If a traditional cohort study was linked to an Internet-based study, both studies could benefit from added synergy. Existing cohort studies provide an opportunity to develop and test processes for cohort linkage. The Crohn's and Colitis Foundation of America's (CCFA) Partners study is an Internet-based cohort of more than 14,000 participants. The Ocean State Crohn's and Colitis Area Registry (OSCCAR) is an inception cohort. The Sinai-Helmsley Alliance for Research Excellence (SHARE) is a multicentered cohort of inflammatory bowel disease patients. Both the later cohorts include medical record abstraction, patient surveys, and biospecimen collection. Objective: Given the complementary nature of these existing cohorts, we sought to corecruit and link data. Methods: Eligible OSCCAR and SHARE participants were invited to join the CCFA Partners study and provide consent for data sharing between the 2 cohorts. After informed consent, participants were directed to the CCFA Partners website to complete enrollment and a baseline Web-based survey. Participants were linked across the 2 cohorts by the matching of an email address. We compared demographic and clinical characteristics between OSCCAR and SHARE participants who did and did not enroll in CCFA Partners and the data linkage. Results: Of 408 participants in the OSCCAR cohort, 320 were eligible for participation in the CCFA Partners cohort. Of these participants, 243 consented to participation; however, only 44 enrolled in CCFA Partners and completed the linkage. OSCCAR participants who enrolled in CCFA Partners were better educated (17% with doctoral degrees) than those who did not (3% with doctoral degrees, P=.01). In the SHARE cohort, 436 participants enrolled and linked to the Partners cohort. More women (60% vs 50%) linked and those who linked were predominantly white (96%; P<.01). Crohn's disease patients who linked had lower mean scores on the Harvey-Bradshaw Index (3.6 vs 4.4, P<.01). Ulcerative colitis patients who linked had less extensive disease than those who did not link (45% vs 60%, P<.01). Conclusions: Linkage of CCFA Partners with cohorts such as OSCCAR and SHARE may be a cost-effective way to expand the infrastructure for clinical outcomes and translational research. Although linkage is feasible from a technical, legal, and regulatory perspective, participant willingness appears to be a limiting factor. Overcoming this barrier will be needed to generate meaningful sample sizes to conduct studies of biomarkers, natural history, and clinical effectiveness using linked data

Analysis of LIGO data for gravitational waves from binary neutron stars

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$per year per Milky Way Equivalent Galaxy (MWEG), with 90coalescence rate of binary systems in which each component has a mass in the range 1--3$M_\odot$.Comment: 17 pages, 9 figure