43 research outputs found

    3-quasi-Sasakian manifolds

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    In the present paper we carry on a systematic study of 3-quasi-Sasakian manifolds. In particular we prove that the three Reeb vector fields generate an involutive distribution determining a canonical totally geodesic and Riemannian foliation. Locally, the leaves of this foliation turn out to be Lie groups: either the orthogonal group or an abelian one. We show that 3-quasi-Sasakian manifolds have a well-defined rank, obtaining a rank-based classification. Furthermore, we prove a splitting theorem for these manifolds assuming the integrability of one of the almost product structures. Finally, we show that the vertical distribution is a minimum of the corrected energy.Comment: 17 pages, minor modifications, references update

    Volume I. Introduction to DUNE

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    The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae 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 Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. This TDR is intended to justify the technical choices for the far detector that flow down from the high-level physics goals through requirements at all levels of the Project. Volume I contains an executive summary that introduces the DUNE science program, the far detector and the strategy for its modular designs, and the organization and management of the Project. The remainder of Volume I provides more detail on the science program that drives the choice of detector technologies and on the technologies themselves. It also introduces the designs for the DUNE near detector and the DUNE computing model, for which DUNE is planning design reports. Volume II of this TDR describes DUNE\u27s physics program in detail. Volume III describes the technical coordination required for the far detector design, construction, installation, and integration, and its organizational structure. Volume IV describes the single-phase far detector technology. A planned Volume V will describe the dual-phase technology

    Deep Underground Neutrino Experiment (DUNE), far detector technical design report, volume III: DUNE far detector technical coordination

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    The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae 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 Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. Volume III of this TDR describes how the activities required to design, construct, fabricate, install, and commission the DUNE far detector modules are organized and managed. This volume details the organizational structures that will carry out and/or oversee the planned far detector activities safely, successfully, on time, and on budget. It presents overviews of the facilities, supporting infrastructure, and detectors for context, and it outlines the project-related functions and methodologies used by the DUNE technical coordination organization, focusing on the areas of integration engineering, technical reviews, quality assurance and control, and safety oversight. Because of its more advanced stage of development, functional examples presented in this volume focus primarily on the single-phase (SP) detector module

    Carboxyl ester hydrolases production and growth of a halophilic archaeon, Halobacterium sp. NRC-1

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    The capability of Halobacterium sp. NRC-1 to synthesize carboxyl ester hydrolases was investigated, and the effect of physicochemical conditions on the growth rate and production of esterases was evaluated. The haloarchaeon synthesized a carboxyl ester hydrolase, confirming the genomic prediction. This enzymatic activity was intracellularly produced as a growth-associated metabolite. Esterase activity was assayed using different p-nitrophenyl-esters and triacyl-glycerides, which showed a preference for hydrolyzing tributyrin. The archaeal growth rate and esterase production were significantly influenced by the pH and the NaCl concentration. An interaction effect between temperature and NaCl was also seen. The maximal growth rate and esterase production found for Halobacterium sp. NRC-1 were 0.136 h-1 (at 4.2 M NaCl, pH 6 and 44�C) and 1.64 U/l (at 4.6 M NaCl, pH 6 and 30�C), respectively. Furthermore, the effects of NaCl concentration, pH and temperature on enzyme activity were studied. Two maximal esterase activities were elucidated from the intracellular crude extract when it was incubated at different NaCl concentrations (1 M and 5 M) and at different pHs (6 and 7.5). This is the first report that shows experimentally the synthesis of carboxyl ester hydrolases by Halobacterium sp. NRC-1. This enzyme was found to be extremely halophilic (5 M NaCl) and thermophilic (80�C), making it very interesting for future investigations in non-aqueous biocatalysis. � Springer 2009

    Controlling Healing and Toughness in Polyurethanes by Branch-Mediated Tube Dilation

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    In this work, we propose the use of regular branching of polyurethanes as a way to regulate chain dynamics and govern crystallization in highly dense hydrogen-bonded systems. As a result, robust and healable polyurethanes can be obtained. To this end, we synthesized a range of aliphatic propane diol derivatives with alkyl branches ranging from butyl (C4) to octadecanyl (C18). The series of brush polyurethanes was synthesized by polyaddition of the diols and hexamethylene diisocyanate. Polyurethanes with very short (C 4) and very long (C = 18) brush lengths did not lead to any significant healing due to crystallization. An intermediate amorphous regime appears for polymers with middle branch lengths (C = 4 to 8) showing a fine control of material toughness. For these systems, the side chain length regulates tube dilation, and significant macroscopic healing of cut samples was observed and studied in detail using melt rheology and tensile testing. Despite the high healing degrees observed immediately after repair, it was found that samples with medium to long length brushes lost their interfacial strength at the healed site after being heated to the healing temperature for some time after the optimal time to reach full healing. Dedicated testing suggests that annealed samples, while keeping initial tackiness, are not able to completely heal the cut interface. We attribute such behavior to annealing-induced interfacial crystallization promoted by the aliphatic branches. Interestingly, no such loss of healing due to annealing was observed for samples synthesized with C4 and C7 diols, which is identified as the optimal healing regime. These results point at the positive effect of branching on healing, provided that a critical chain length is not surpassed, as well as the need to study healing behavior long after the optimal healing times.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Novel Aerospace Material

    Effect of hormone replacement therapy on cardiac autonomic modulation

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    Objective: To investigate the effects of hormone replacement therapy (HRT) on heart rate variability (HRV) in healthy postmenopausal women. Methods: Two groups were evaluated: group 1 (G1): 20 women not undergoing HRT (60 \ub1 5.89 years), group 2 (G2): 20 women undergoing HRT (59 \ub1 5.70 years). The HRTs involved were either conjugated equine estrogen with or without medroxyprogesterone, synthetic estrogen hormone, estradiol associated with norethisterone acetate or isoflavonoids. Electrocardiogram was recorded in the supine position for 10 min. Spectral analysis included low and high frequencies in absolute (LF and HF) and normalized units (LFnu and HFnu), which are predominantly cardiac sympathetic modulation (CSM) and cardiac vagal modulation (CVM) indicators, respectively. The LF/HF ratio was also calculated. Symbolic analysis involved the following indexes: 0V % (CSM indicator), 1V % (CSM and CVM indicators), 2LV % (predominantly CVM indicator) and 2UV % (CVM indicator). Shannon and conditional entropies were also calculated. Results: Spectral analysis demonstrated that HRT affected HRV. LF, LFnu and LF/HF ratio were higher (showing increased CSM), while HFnu was lower (representing decreased CVM) in G2 than in G1. Correlations between complexity indices and HFnu were significant and positive only in G1. Interpretation: Women undergoing HRT presented higher CSM and lower CVM than those who were not. Moreover, the expected positive relationship between CVM and complexity of HRV was found only in control group, thus indicating that CVM in women under therapy drop below a minimal value necessary to the association to become apparent, suggesting an unfavorable cardiac autonomic modulation in spite of HRT
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