1,087 research outputs found

    Development of a high-resolution target movement monitoring system for convergence monitoring in mines

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    The research performed for this dissertation has been conducted with the goal of developing a ground convergence monitor that may better meet the needs of some mines, leading to increased use of ground monitoring programs and reduced fatality rates from falling and sliding rock. The developed monitor is a convergence monitor capable of achieving sensitivities similar to those of currently available convergence meters such as tape extensometers. The monitor is inexpensive and is capable of totally remote operation in some circumstances...A physical model of the meter was developed based on experimental results and compared to a derived theoretical model to show that the monitor was capable of accurately reproducing the predicted sensitivity values --Abstract, page iii

    A formally verified compiler back-end

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    This article describes the development and formal verification (proof of semantic preservation) of a compiler back-end from Cminor (a simple imperative intermediate language) to PowerPC assembly code, using the Coq proof assistant both for programming the compiler and for proving its correctness. Such a verified compiler is useful in the context of formal methods applied to the certification of critical software: the verification of the compiler guarantees that the safety properties proved on the source code hold for the executable compiled code as well

    CMBPol Mission Concept Study: Probing Inflation with CMB Polarization

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    We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to differentiate various inflationary mechanisms. In particular, a detection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters.Comment: 107 pages, 14 figures, 17 tables; Inflation Working Group contribution to the CMBPol Mission Concept Study; v2: typos fixed and references adde

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    Three long period transiting giant planets from TESS

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    We report the discovery and orbital characterization of three new transiting warm giant planets. These systems were initially identified as presenting single transit events in the light curves generated from the full frame images of the Transiting Exoplanet Survey Satellite (TESS). Follow-up radial velocity measurements and additional light curves were used to determine the orbital periods and confirm the planetary nature of the candidates. The planets orbit slightly metal-rich late F- and early G-type stars. We find that TOI 4406b has a mass of MPM_P= 0.30 ±\pm 0.04 MJM_J , a radius of RPR_P= 1.00 ±\pm 0.02 RJR_J , and a low eccentricity orbit (e=0.15 ±\pm 0.05) with a period of P= 30.08364 ±\pm 0.00005 d . TOI 2338b has a mass of MPM_P= 5.98 ±\pm 0.20 MJM_J , a radius of RPR_P= 1.00 ±\pm 0.01 RJR_J , and a highly eccentric orbit (e= 0.676 ±\pm 0.002 ) with a period of P= 22.65398 ±\pm 0.00002 d . Finally, TOI 2589b has a mass of MPM_P= 3.50 ±\pm 0.10 MJM_J , a radius of RPR_P= 1.08 ±\pm 0.03 RJR_J , and an eccentric orbit (e = 0.522 ±\pm 0.006 ) with a period of P= 61.6277 ±\pm 0.0002 d . TOI 4406b and TOI 2338b are enriched in metals compared to their host stars, while the structure of TOI 2589b is consistent with having similar metal enrichment to its host star.Comment: 24 pages, 16 figures, accepted in A

    TOI-199 b: A well-characterized 100-day transiting warm giant planet with TTVs seen from Antarctica

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    We present the spectroscopic confirmation and precise mass measurement of the warm giant planet TOI-199 b. This planet was first identified in TESS photometry and confirmed using ground-based photometry from ASTEP in Antarctica including a full 6.5 \,h long transit, PEST, Hazelwood, and LCO; space photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS, CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199\,b has a 104.854−0.002+0.001 d\mathrm{104.854_{-0.002}^{+0.001} \, d} period, a mass of 0.17±0.02 MJ\mathrm{0.17\pm0.02 \, M_J}, and a radius of 0.810±0.005 RJ\mathrm{0.810\pm0.005 \, R_J}. It is the first warm exo-Saturn with a precisely determined mass and radius. The TESS and ASTEP transits show strong transit timing variations, pointing to the existence of a second planet in the system. The joint analysis of the RVs and TTVs provides a unique solution for the non-transiting companion TOI-199 c, which has a period of 273.69−0.22+0.26 d\mathrm{273.69_{-0.22}^{+0.26} \, d} and an estimated mass of 0.28−0.01+0.02 MJ\mathrm{0.28_{-0.01}^{+0.02} \, M_J}. This period places it within the conservative Habitable Zone.Comment: 33 pages, 23 figures. Accepted for publication in A

    Observing convective aggregation

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    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad a distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network

    Three Saturn-mass planets transiting F-type stars revealed with TESS and HARPS

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    While the sample of confirmed exoplanets continues to increase, the population of transiting exoplanets around early-type stars is still limited. These planets allow us to investigate the planet properties and formation pathways over a wide range of stellar masses and study the impact of high irradiation on hot Jupiters orbiting such stars. We report the discovery of TOI-615b, TOI-622b, and TOI-2641b, three Saturn-mass planets transiting main sequence, F-type stars. The planets were identified by the Transiting Exoplanet Survey Satellite (TESS) and confirmed with complementary ground-based and radial velocity observations. TOI-615b is a highly irradiated (∌\sim1277 F⊕F_{\oplus}) and bloated Saturn-mass planet (1.69−0.06+0.05^{+0.05}_{-0.06}RJupR_{Jup} and 0.43−0.08+0.09^{+0.09}_{-0.08}MJupM_{Jup}) in a 4.66 day orbit transiting a 6850 K star. TOI-622b has a radius of 0.82−0.03+0.03^{+0.03}_{-0.03}RJupR_{Jup} and a mass of 0.30−0.08+0.07^{+0.07}_{-0.08}~MJupM_{Jup} in a 6.40 day orbit. Despite its high insolation flux (∌\sim600 F⊕F_{\oplus}), TOI-622b does not show any evidence of radius inflation. TOI-2641b is a 0.37−0.04+0.05^{+0.05}_{-0.04}MJupM_{Jup} planet in a 4.88 day orbit with a grazing transit (b = 1.04−0.06+0.05^{+0.05}_{-0.06 }) that results in a poorly constrained radius of 1.61−0.64+0.46^{+0.46}_{-0.64}RJupR_{Jup}. Additionally, TOI-615b is considered attractive for atmospheric studies via transmission spectroscopy with ground-based spectrographs and JWST\textit{JWST}. Future atmospheric and spin-orbit alignment observations are essential since they can provide information on the atmospheric composition, formation and migration of exoplanets across various stellar types.Comment: 16 pages, 17 figures, submitted to A&

    Evidence for Loss of a Partial Flagellar Glycolytic Pathway during Trypanosomatid Evolution

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    Classically viewed as a cytosolic pathway, glycolysis is increasingly recognized as a metabolic pathway exhibiting surprisingly wide-ranging variations in compartmentalization within eukaryotic cells. Trypanosomatid parasites provide an extreme view of glycolytic enzyme compartmentalization as several glycolytic enzymes are found exclusively in peroxisomes. Here, we characterize Trypanosoma brucei flagellar proteins resembling glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoglycerate kinase (PGK): we show the latter associates with the axoneme and the former is a novel paraflagellar rod component. The paraflagellar rod is an essential extra-axonemal structure in trypanosomes and related protists, providing a platform into which metabolic activities can be built. Yet, bioinformatics interrogation and structural modelling indicate neither the trypanosome PGK-like nor the GAPDH-like protein is catalytically active. Orthologs are present in a free-living ancestor of the trypanosomatids, Bodo saltans: the PGK-like protein from B. saltans also lacks key catalytic residues, but its GAPDH-like protein is predicted to be catalytically competent. We discuss the likelihood that the trypanosome GAPDH-like and PGK-like proteins constitute molecular evidence for evolutionary loss of a flagellar glycolytic pathway, either as a consequence of niche adaptation or the re-localization of glycolytic enzymes to peroxisomes and the extensive changes to glycolytic flux regulation that accompanied this re-localization. Evidence indicating loss of localized ATP provision via glycolytic enzymes therefore provides a novel contribution to an emerging theme of hidden diversity with respect to compartmentalization of the ubiquitous glycolytic pathway in eukaryotes. A possibility that trypanosome GAPDH-like protein additionally represents a degenerate example of a moonlighting protein is also discussed
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