84 research outputs found

    On the Apparent Orbital Inclination Change of the Extrasolar Transiting Planet TrES-2b

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    On June 15, 2009 UT the transit of TrES-2b was detected using the University of Arizona's 1.55 meter Kuiper Telescope with 2.0-2.5 millimag RMS accuracy in the I-band. We find a central transit time of Tc=2454997.76286±0.00035T_c = 2454997.76286 \pm0.00035 HJD, an orbital period of P=2.4706127±0.0000009P = 2.4706127 \pm 0.0000009 days, and an inclination angle of i=83.92±0.05i = 83^{\circ}.92 \pm 0.05, which is consistent with our re-fit of the original I-band light curve of O'Donovan et al. (2006) where we find i=83.84±0.05i = 83^{\circ}.84 \pm0.05. We calculate an insignificant inclination change of Δi=0.08±0.07\Delta i = -0^{\circ}.08 \pm 0.07 over the last 3 years, and as such, our observations rule out, at the 11σ\sim 11 \sigma level, the apparent change of orbital inclination to ipredicted=83.35±0.1i_{predicted} = 83^{\circ}.35 \pm0.1 as predicted by Mislis and Schmitt (2009) and Mislis et al. (2010) for our epoch. Moreover, our analysis of a recently published Kepler Space Telescope light curve (Gilliland et al. 2010) for TrES-2b finds an inclination of i=83.91±0.03i = 83^{\circ}.91 \pm0.03 for a similar epoch. These Kepler results definitively rule out change in ii as a function of time. Indeed, we detect no significant changes in any of the orbital parameters of TrES-2b.Comment: 19 pages, 1 table, 7 figures. Re-submitted to ApJ, January 14, 201

    A Tentative Detection of a Starspot During Consecutive Transits of an Extrasolar Planet from the Ground: No Evidence of a Double Transiting Planet System Around TrES-1

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    There have been numerous reports of anomalies during transits of the planet TrES-1b. Recently, Rabus and coworkers' analysis of HST observations lead them to claim brightening anomalies during transit might be caused by either a second transiting planet or a cool starspot. Observations of two consecutive transits are presented here from the University of Arizona's 61-inch Kuiper Telescope on May 12 and May 15, 2008 UT. A 5.4 +/- 1.7 mmag (0.54 +/- 0.17%) brightening anomaly was detected during the first half of the transit on May 12 and again in the second half of the transit on May 15th. We conclude that this is a tentative detection of a r greater than or equal to 6 earth radii starspot rotating on the surface of the star. We suggest that all evidence to date suggest TrES-1 has a spotty surface and there is no need to introduce a second transiting planet in this system to explain these anomalies. We are only able to constrain the rotational period of the star to 40.2 +22.9 -14.6 days, due to previous errors in measuring the alignment of the stellar spin axis with the planetary orbital axis. This is consistent with the previously observed P_obs = 33.2 +22.3 -14.3 day period. We note that this technique could be applied to other transiting systems for which starspots exist on the star in the transit path of the planet in order to constrain the rotation rate of the star. (abridged)Comment: 21 pages, 3 tables, 6 figures, Accepted to Ap

    Developmental expression patterns ofTbx1,Tbx2,Tbx5, andTbx20 inXenopus tropicalis

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    T-box genes have diverse functions during embryogenesis and are implicated in several human congenital disorders. Here, we report the identification, sequence analysis, and developmental expression patterns of four members of the T-box gene family in the diploid frog Xenopus tropicalis. These four genes—Tbx1, Tbx2, Tbx5, and Tbx20—have been shown to influence cardiac development in a variety of organisms, in addition to their individual roles in regulating other aspects of embryonic development. Our results highlight the high degree of evolutionary conservation between orthologs of these genes in X. tropicalis and other vertebrates, both at the molecular level and in their developmental expression patterns, and also identify novel features of their expression. Thus, X. tropicalis represents a potentially valuable vertebrate model in which to further investigate the functions of these genes through genetic approaches

    Follow-up Observations of the Neptune Mass Transiting Extrasolar Planet HAT-P-11b

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    We have confirmed the existence of the transiting super Neptune extrasolar planet HAT-P-11b. On May 1, 2009 UT the transit of HAT-P-11b was detected at the University of Arizona's 1.55m Kuiper Telescope with 1.7 millimag rms accuracy. We find a central transit time of T_c = 2454952.92534+/-0.00060 BJD; this transit occurred 80+/-73 seconds sooner than previous measurements (71 orbits in the past) would have predicted. Hence, our transit timing rules out the presence of any large (>200 s) deviations from the ephemeris of Bakos et al. (2009). We obtain a slightly more accurate period of P=4.8878045+/-0.0000043 days. We measure a slightly larger planetary radius of R_p=0.452+/-0.020 R_J (5.07+/-0.22 R_earth) compared to Bakos and co-workers' value of 0.422+/-0.014 R_J (4.73+/-0.16 R_earth). Our values confirm that HAT-P-11b is very similar to GJ 436b (the only other known transiting super Neptune) in radius and other bulk properties.Comment: accepted to ApJ Letters, 11 pages, 2 figures (see Dittmann et al. 2009 ApJ 699 L48-L51

    Can Neutron Star Mergers Alone Explain the r-process Enrichment of the Milky Way?

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    © 2023. The Author(s). Published by the American Astronomical Society. This is an open access article under the terms of the Creative Commons Attribution License, https://creativecommons.org/licenses/by/4.0/Comparing Galactic chemical evolution models to the observed elemental abundances in the Milky Way, we show that neutron star mergers can be a leading r-process site only if at low metallicities such mergers have very short delay times and significant ejecta masses that are facilitated by the masses of the compact objects. Namely, black hole–neutron star mergers, depending on the black hole spins, can play an important role in the early chemical enrichment of the Milky Way. We also show that none of the binary population synthesis models used in this Letter, i.e., COMPAS, StarTrack, Brussels, ComBinE, and BPASS, can currently reproduce the elemental abundance observations. The predictions are problematic not only for neutron star mergers, but also for Type Ia supernovae, which may point to shortcomings in binary evolution models.Peer reviewe

    The role of microRNA-1 and microRNA-133 in skeletal muscle proliferation and differentiation

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    Understanding the molecular mechanisms that regulate cellular proliferation and differentiation is a central theme of developmental biology. MicroRNAs (miRNAs) are a class of regulatory RNAs of ~22 nucleotides that post-transcriptionally regulate gene expression1,2. Increasing evidence points to the potential role of miRNAs in various biological processes3–8. Here we show that miRNA-1 (miR-1) and miRNA-133 (miR-133), which are clustered on the same chromosomal loci, are transcribed together in a tissue-specific manner during development. miR-1 and miR-133 have distinct roles in modulating skeletal muscle proliferation and differentiation in cultured myoblasts in vitro and in Xenopus laevis embryos in vivo. miR-1 promotes myogenesis by targeting histone deacetylase 4 (HDAC4), a transcriptional repressor of muscle gene expression. By contrast, miR-133 enhances myoblast proliferation by repressing serum response factor (SRF). Our results show that two mature miRNAs, derived from the same miRNA polycistron and transcribed together, can carry out distinct biological functions. Together, our studies suggest a molecular mechanism in which miRNAs participate in transcriptional circuits that control skeletal muscle gene expression and embryonic development

    Whole brain radiotherapy (WBRT) after local treatment of brain metastases in melanoma patients: Statistical Analysis Plan

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    Background: The WBRTMel trial is a multinational, open-label, phase III randomised controlled trial comparing whole brain radiotherapy (WBRT) to observation following local treatment of one to three melanoma brain metastases with surgery and/or stereotactic irradiation. The primary trial endpoint was to determine the effect of adding WBRT to local treatment on distant intracranial control, and the secondary endpoints were neurocognitive function, quality of life (QoL), performance status, overall survival, death from intracranial causes, death from melanoma and cost-effectiveness. Objective: The objective of this update is to outline and publish the pre-determined statistical analysis plan (SAP) before the database lock and the start of analysis. Methods: The SAP describes basic analysis principles, methods for dealing with a range of commonly encountered data analysis issues and the specific statistical procedures for analysing efficacy and safety outcomes. The SAP was approved after closure of recruitment and before completion of patient follow-up. It outlines the planned primary analyses and a range of subgroup and sensitivity analyses regarding the clinical and QoL outcomes. Health economic outcomes are not included in this plan but will be analysed separately. The SAP will be adhered to for the final data analysis of this trial to avoid analysis bias arising from knowledge of the data. Results: The resulting SAP is consistent with best practice and will allow open and transparent reporting. Conclusion: We have developed a SAP for the WBRTMel trial which will be followed to ensure high-quality standards of internal validity to minimise analysis bias

    Gliomas and Farm Pesticide Exposure in Women: The Upper Midwest Health Study

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    An excess incidence of brain cancer in male farmers has been noted in several studies, but few studies have focused on women. The National Institute for Occupational Safety and Health Upper Midwest Health Study evaluated effects of rural exposures for 341 female glioma cases and 528 controls, all adult (18–80 years of age) nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. On average, controls lived longer on farms than did cases. After adjusting for age, age group, education, and farm residence, no association with glioma was observed for exposure to arsenicals, benzoic acids, carbamates, chloroacetanilides, dinitroanilines, inorganics, organochlorines, organophosphates, phenoxys, triazines, or urea-based or estrogenic pesticides. An increased risk of glioma was observed for carbamate herbicides but was not statistically significant (odds ratio = 3.0; 95% confidence interval, 0.9–9.5). No association was observed between glioma and exposure to 12 widely used specific pesticides, after adjustment for age, age group, education, and any other pesticide exposure. These results were not affected after exclusion of proxy respondents (43% of cases, 2% of controls). Women were less likely than men to have applied pesticides, but more likely to have laundered pesticide-contaminated clothes. Storing pesticides in the house was associated with a statistically non-significant increased risk. Results show that exposure to pesticides was not associated with an increased risk of intracranial gliomas in women. Other farm-related factors could be etiologic factors and will be discussed in future reports

    A multilevel intervention to promote colorectal cancer screening among community health center patients: results of a pilot study

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    <p>Abstract</p> <p>Background</p> <p>Colorectal cancer screening rates are low among poor and disadvantaged patients. Patient navigation has been shown to increase breast and cervical cancer screening rates, but few studies have looked at the potential of patient navigation to increase colorectal cancer screening rates.</p> <p>Methods</p> <p>The objective was to determine the feasibility and effectiveness of a patient navigator-based intervention to increase colorectal cancer screening rates in community health centers. Patients at the intervention health center who had not been screened for colorectal cancer and were designated as "appropriate for outreach" by their primary care providers received a letter from their provider about the need to be screened and a brochure about colorectal cancer screening. Patient navigators then called patients to discuss screening and to assist patients in obtaining screening. Patients at a demographically similar control health center received usual care.</p> <p>Results</p> <p>Thirty-one percent of intervention patients were screened at six months, versus nine percent of control patients (p < .001).</p> <p>Conclusion</p> <p>A patient navigator-based intervention, in combination with a letter from the patient's primary care provider, was associated with an increased rate of colorectal cancer screening at one health center as compared to a demographically similar control health center. Our study adds to an emerging literature supporting the use of patient navigators to increase colorectal cancer screening in diverse populations served by urban health centers.</p
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