151 research outputs found

    Investigation of Relationships between Urinary Biomarkers of Phytoestrogens, Phthalates, and Phenols and Pubertal Stages in Girls

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    BackgroundHormonally active environmental agents may alter the course of pubertal development in girls, which is controlled by steroids and gonadotropins.ObjectivesWe investigated associations of concurrent exposures from three chemical classes (phenols, phthalates, and phytoestrogens) with pubertal stages in a multiethnic longitudinal study of 1,151 girls from New York City, New York, greater Cincinnati, Ohio, and northern California who were 6-8 years of age at enrollment (2004-2007).MethodsWe measured urinary exposure biomarkers at visit 1 and examined associations with breast and pubic hair development (present or absent, assessed 1 year later) using multivariate adjusted prevalence ratios (PR) and 95% confidence intervals (CIs). Modification of biomarker associations by age-specific body mass index percentile (BMI%) was investigated, because adipose tissue is a source of peripubertal hormones.ResultsBreast development was present in 30% of girls, and 22% had pubic hair. High-molecular-weight phthalate (high MWP) metabolites were weakly associated with pubic hair development [adjusted PR, 0.94 (95% CI, 0.88-1.00), fifth vs. first quintile]. Small inverse associations were seen for daidzein with breast stage and for triclosan and high MWP with pubic hair stage; a positive trend was observed for low-molecular-weight phthalate biomarkers with breast and pubic hair development. Enterolactone attenuated BMI associations with breast development. In the first enterolactone quintile, for the association of high BMI with any development, the PR was 1.34 (95% CI, 1.23-1.45 vs. low BMI). There was no BMI association in the fifth, highest quintile of enterolactone.ConclusionsWeak hormonally active xenobiotic agents investigated in this study had small associations with pubertal development, mainly among those agents detected at highest concentrations

    The concept of RNA-assisted protein folding: the role of tRNA

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    We suggest that tRNA actively participates in the transfer of 3D information from mRNA to peptides - in addition to its well-known, "classical" role of translating the 3-letter RNA codes into the one letter protein code. The tRNA molecule displays a series of thermodynamically favored configurations during translation, a movement which places the codon and coded amino acids in proximity to each other and make physical contact between some amino acids and their codons possible. This specific codon-amino acid interaction of some selected amino acids is necessary for the transfer of spatial information from mRNA to coded proteins, and is known as RNA-assisted protein folding

    Liquid metal embrittlement in laser lap joining of TWIP and medium-manganese TRIP steel: The role of stress and grain boundaries

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    The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.matchar.2018.09.018 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/High-Manganese austenite-containing steels with superior combination of strength and ductility have shown potential for enhancement of passenger safety and body-in-white (BIW) weight reduction. Even though Zn-coated austenitic steels have improved corrosion resistance, they are highly susceptible to liquid metal embrittlement (LME) during welding. The present work is aimed to address LME susceptibility during restrained laser lap joining of high-Mn twinning induced plasticity (TWIP) and medium-Mn transformation induced plasticity (MMn-TRIP) steels. Electron probe micro-analysis (EPMA) results showed that stress-assisted diffusion of Zn into the austenite grain boundaries and further liquid Zn formation by a peritectic reaction lead to grain boundary decohesion. Electron backscatter diffraction (EBSD) results demonstrated that high angle and special grain boundaries are prone to Zn-penetration within the heat-affected-zone (HAZ). Additionally, LME sensitivity was observed to be highly dependent on the magnitude of applied stress.Natural Sciences and Engineering Research Council of Canad

    Pilot Study of Urinary Biomarkers of Phytoestrogens, Phthalates, and Phenols in Girls

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    BACKGROUND: Hormonally active environmental agents have been measured among U.S. children using exposure biomarkers in urine. However, little is known about their variation by race, age, sex, and geography, and no data exist for newly developed biomarkers. OBJECTIVE: Our goal was to characterize relevant, prevalent exposures for a study of female pubertal development. METHODS: In a pilot study among 90 girls from New York City, New York, Cincinnati, Ohio, and northern California, we measured 25 urinary analytes representing 22 separate agents from three chemical families: phytoestrogens, phthalates, and phenols. Exposures occur chiefly from the diet and from household or personal care products. RESULTS: Participants represented four racial/ethnic groups (Asian, black, Hispanic, white), with mean age of 7.77 years. Most analytes were detectable in > 94% of samples. The highest median concentrations for individual analytes in each family were for enterolactone (298 μg/L), monoethylphthalate (MEP; 83.2 μg/L), and benzophenone-3 (BP3; 14.7 μg/L). Few or no data have been reported previously for four metabolites: mono(2-ethyl-5-carboxypentyl) phthalate, triclosan, bisphenol A (BPA), and BP3; these were detected in 67–100% of samples with medians of 1.8–53.2 μg/L. After multivariate adjustment, two analytes, enterolactone and BPA, were higher among girls with body mass index < 85th reference percentile than those at or above the 85th percentile. Three phthalate metabolites differed by race/ethnicity [MEP, mono(2-ethylhexyl) phthalate, and mono-3-carboxypropylphthalate]. CONCLUSIONS: A wide spectrum of hormonally active exposure biomarkers were detectable and variable among young girls, with high maximal concentrations (> 1,000 μg/L) found for several analytes. They varied by characteristics that may be relevant to development

    Does codon bias have an evolutionary origin?

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    <p>Abstract</p> <p>Background</p> <p>There is a 3-fold redundancy in the Genetic Code; most amino acids are encoded by more than one codon. These synonymous codons are not used equally; there is a Codon Usage Bias (CUB). This article will provide novel information about the origin and evolution of this bias.</p> <p>Results</p> <p>Codon Usage Bias (CUB, defined here as deviation from equal usage of synonymous codons) was studied in 113 species. The average CUB was 29.3 ± 1.1% (S.E.M, n = 113) of the theoretical maximum and declined progressively with evolution and increasing genome complexity. A Pan-Genomic Codon Usage Frequency (CUF) Table was constructed to describe genome-wide relationships among codons. Significant correlations were found between the number of synonymous codons and (i) the frequency of the respective amino acids (ii) the size of CUB. Numerous, statistically highly significant, internal correlations were found among codons and the nucleic acids they comprise. These strong correlations made it possible to predict missing synonymous codons (wobble bases) reliably from the remaining codons or codon residues.</p> <p>Conclusion</p> <p>The results put the concept of "codon bias" into a novel perspective. The internal connectivity of codons indicates that all synonymous codons might be integrated parts of the Genetic Code with equal importance in maintaining its functional integrity.</p

    Dyson-Schwinger Equations: Density, Temperature and Continuum Strong QCD

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    Continuum strong QCD is the application of models and continuum quantum field theory to the study of phenomena in hadronic physics, which includes; e.g., the spectrum of QCD bound states and their interactions; and the transition to, and properties of, a quark gluon plasma. We provide a contemporary perspective, couched primarily in terms of the Dyson-Schwinger equations but also making comparisons with other approaches and models. Our discourse provides a practitioners' guide to features of the Dyson-Schwinger equations [such as confinement and dynamical chiral symmetry breaking] and canvasses phenomenological applications to light meson and baryon properties in cold, sparse QCD. These provide the foundation for an extension to hot, dense QCD, which is probed via the introduction of the intensive thermodynamic variables: chemical potential and temperature. We describe order parameters whose evolution signals deconfinement and chiral symmetry restoration, and chronicle their use in demarcating the quark gluon plasma phase boundary and characterising the plasma's properties. Hadron traits change in an equilibrated plasma. We exemplify this and discuss putative signals of the effects. Finally, since plasma formation is not an equilibrium process, we discuss recent developments in kinetic theory and its application to describing the evolution from a relativistic heavy ion collision to an equilibrated quark gluon plasma.Comment: 103 Pages, LaTeX, epsfig. To appear in Progress in Particle and Nuclear Physics, Vol. 4

    Accretion Discs with an Inner Spiral Density Wave

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    In Montgomery (2009a), we show that accretion discs in binary systems could retrogradely precess by tidal torques like the Moon and the Sun on a tilted, spinning, non-spherical Earth. In addition, we show that the state of matter and the geometrical shape of the celestial object could significantly affect the precessional value. For example, a Cataclysmic Variable (CV) Dwarf Novae (DN) non-magnetic system that shows negative superhumps in its light curve can be described by a retrogradely precessing, differentially rotating, tilted disc. Because the disc is a fluid and because the gas stream overflows the tilted disc and particles can migrate into inner disc annuli, coupled to the disc could be a retrogradely precessing inner ring that is located near the innermost annuli of the disc. However, numerical simulations by Bisikalo et al. (2003, 2004) and this work show that an inner spiral density wave can be generated instead of an inner ring. Therefore, we show that retrograde precession in non-magnetic, spinning, tilted CV DN systems can equally be described by a retrogradely precessing and differentially rotating disc with an attached retrogradely precessing inner spiral density wave so long as the wave appears at the same radius as the ring and within the plane of the tilted disc. We find that the theoretical results generated in this work agree well with the theoretical results presented in Montgomery (2009a) and thus with the numerical simulations and select CV DN systems in Montgomery (2009b) that may have a main sequence secondary. Therefore, pressure effects do need to be considered in CV DN systems that exhibit negative superhumps if the accretion discs are tilted and have an inner spiral density wave that is in the plane of the disc

    The Vehicle, 1969, Vol. 11 no. 2

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    Vol. 11, No. 2 Table of Contents Short Story: The TripCharles Whitepage 4 PhotoDale Huberpage 5 A NightRoger Zulaufpage 6 Sixteen-year-old Students...NBpage 6 LostJim Biropage 6 The AmateurRoger Zulaufpage 7 ManRoger Zulaufpage 7 My CamelotRonald Garnerpage 7 The Rose and the BriarKenneth L. Folkertspage 9 Who Am I?Frank McKennedypage 10 PhotoDale Huberpage 11 Mr. Samuel ClemensLarry A. Millerpage 11 Lock OutAra Childspage 12 Excuse MeRoger Zulaufpage 12 On Shadows from a Candle \u2767Michael G. McKeepage 12 beginning of an endCaryl Dagropage 12 DrawingMADpage 13 We Ain\u27t Un HurJames Birchlerpage 13 Genesis II, 18 \u2767Michael G. McKeepage 13 Short Story: A Patent Leather PaleEleanor Aikenpage 14 hungry childRoger Zulaufpage 15 DrawingRoger Zulaufpage 15 PhotoRoger Digglepage 16 Do You Like The Rain?Linda Boltmanpage 17 Seasons ChangePerry J. Carterpage 17 PhotoDale Huberpage 19 Whistling TreesPam McKinneypage 19 PostscriptThomas W. Reapage 20 PhotoDale Huberpage 20https://thekeep.eiu.edu/vehicle/1020/thumbnail.jp

    The Vehicle, 1969, Vol. 11 no. 2

    Get PDF
    Vol. 11, No. 2 Table of Contents Short Story: The TripCharles Whitepage 4 PhotoDale Huberpage 5 A NightRoger Zulaufpage 6 Sixteen-year-old Students...NBpage 6 LostJim Biropage 6 The AmateurRoger Zulaufpage 7 ManRoger Zulaufpage 7 My CamelotRonald Garnerpage 7 The Rose and the BriarKenneth L. Folkertspage 9 Who Am I?Frank McKennedypage 10 PhotoDale Huberpage 11 Mr. Samuel ClemensLarry A. Millerpage 11 Lock OutAra Childspage 12 Excuse MeRoger Zulaufpage 12 On Shadows from a Candle \u2767Michael G. McKeepage 12 beginning of an endCaryl Dagropage 12 DrawingMADpage 13 We Ain\u27t Un HurJames Birchlerpage 13 Genesis II, 18 \u2767Michael G. McKeepage 13 Short Story: A Patent Leather PaleEleanor Aikenpage 14 hungry childRoger Zulaufpage 15 DrawingRoger Zulaufpage 15 PhotoRoger Digglepage 16 Do You Like The Rain?Linda Boltmanpage 17 Seasons ChangePerry J. Carterpage 17 PhotoDale Huberpage 19 Whistling TreesPam McKinneypage 19 PostscriptThomas W. Reapage 20 PhotoDale Huberpage 20https://thekeep.eiu.edu/vehicle/1020/thumbnail.jp
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