430 research outputs found

    Experimental verification of line- and band-shape asymmetry in the Schumann–Runge system of O[sub 2]

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    High-resolution, laser-based photoabsorption cross-section measurements in the weakly absorbing windows between the (11,0) and (16,0) Schumann–Runge bands of O₂ have been performed at liquid-nitrogen temperature and the results compared with corresponding coupled-channel Schrödinger-equation (CSE) and line-by-line model calculations. While the symmetric-line- shape-based line-by-line model cross sections differ significantly from experiment, the excellent agreement found between the CSE and experimental window cross sections serves to confirm clearly for the first time the CSE-model predictions of band shape asymmetry and quantum-mechanical interference effects, especially in the (11,0)–(14,0) band region

    A bright metastable atom source at 80 K

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    We describe a high flux source of cold (80 K) metastable helium atoms. The source employs a direct current nozzle discharge which produces in excess of 10Âč⁔ atoms/steradian/s. Liquid nitrogen cooling of the discharge source yields atomic velocities below 900 ms⁻Âč. Such a source has practical applications for experiments concerned with laser cooling and trapping of metastable helium atoms

    Potential pitfalls in the accuracy of analysis of natural sense-antisense RNA pairs by reverse transcription-PCR

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    <p>Abstract</p> <p>Background</p> <p>The ability to accurately measure patterns of gene expression is essential in studying gene function. The reverse transcription polymerase chain reaction (RT-PCR) has become the method of choice for the detection and measurement of RNA expression patterns in both cells and small quantities of tissue. Our previous results show that there is a significant production of primer-independent cDNA synthesis using a popular RNase H<sup>- </sup>RT enzyme. A PCR product was amplified from RT reactions that were carried out without addition of RT-primer. This finding jeopardizes the accuracy of RT-PCR when analyzing RNA that is expressed in both orientations. Current literature findings suggest that naturally occurring antisense expression is widespread in the mammalian transcriptome and consists of both coding and non-coding regulatory RNA. The primary purpose of this present study was to investigate the occurrence of primer-independent cDNA synthesis and how it may influence the accuracy of detection of sense-antisense RNA pairs.</p> <p>Results</p> <p>Our findings on cellular RNA and <it>in vitro </it>synthesized RNA suggest that these products are likely the results of RNA self-priming to generate random cDNA products, which contributes to the loss of strand specificity. The use of RNase H<sup>+ </sup>RT enzyme and carrying the RT reaction at high temperature (50°C) greatly improved the strand specificity of the RT-PCR detection.</p> <p>Conclusion</p> <p>While RT PCR is a basic method used for the detection and quantification of RNA expression in cells, primer-independent cDNA synthesis can interfere with RT specificity, and may lead to misinterpretation of the results, especially when both sense and antisense RNA are expressed. For accurate interpretation of the results, it is essential to carry out the appropriate negative controls.</p

    Kenaf Productivity and Morphology. When Grown in Iowa and in Kentucky. Poster Number

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    Natural fibers are a promising alternative to synthetic fibers for reinforcing plastic or other composite materials, or fuel purposes. Kenaf (Hibiscus cannabinus L.), a fiber crop is grown to a limited extent in the U.S. predominantly in the Southern states. Producing kenaf in the Midwestern U.S. could provide a local source of these fibers for use in a number of manufactured products and potentially for use as a biofuel feedstock. The objectives of this study were to: 1) compare the productivity and the morphology of kenaf cultivars ‘Tainung 2’ and ‘Whitten’ when grown in Iowa and Kentucky and harvested after the first killing frost; 2) assess kenaf growth over the growing season; and 3) determine management (variety and seed density) effects on kenaf productivity and morphology. When grown in Kentucky in 2014, Tainung 2 yielded 24 Mg ha-1 whereas Whitten had a yield of 19 Mg ha-1. In contrast, kenaf grown in Iowa showed a yield of 8 Mg ha-1. In 2015, kenaf grown in Iowa and Kentucky had similar yield of 12.6 Mg ha-1 on average. When grown in Iowa, kenaf response to variety and seed density was more stable over time than in Kentucky. Therefore, a producer in Kentucky could influence kenaf productivity by changing management practices and variety. Tainung 2 was in general more sensitive to location and to seed density than Whitten. In 2015, Tainung 2 planted at a denser population produced 30% greater biomass than for Whitten and other seed densities. Whitten performed similarly across locations and seed densities. Growing Tainung 2 in Kentucky produced plants with 16% more core fiber than in Iowa, but using that same variety in Iowa would result in higher bast production. Overall, kenaf production is very feasible in Kentucky and Iowa but Kentucky has greater yield potential

    Non-Lorentzian line shapes for interfering rotational resonances in the predissociation of O(2)

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    Rotationally resolved measurements are presented of interacting predissociating resonances in the Schumann-Runge bands of O₂that exhibit destructive quantum interference for energies between the line centers. The interacting resonances are described using a coupled line shape derived by treating simultaneously the perturbation and predissociation processes using the method of Fano.B. R. Lewis, P. M. Dooley, J. P. England, S. T. Gibson, and K. G. H. Baldwin, L. W. Toro

    Elevated expression of the chemokine-scavenging receptor D6 is associated with impaired lesion development in psoriasis

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    D6 is a scavenging-receptor for inflammatory CC chemokines that are essential for resolution of inflammatory responses in mice. Here, we demonstrate that D6 plays a central role in controlling cutaneous inflammation, and that D6 deficiency is associated with development of a psoriasis-like pathology in response to varied inflammatory stimuli in mice. Examination of D6 expression in human psoriatic skin revealed markedly elevated expression in both the epidermis and lymphatic endothelium in "uninvolved" psoriatic skin (ie, skin that was more than 8 cm distant from psoriatic plaques). Notably, this increased D6 expression is associated with elevated inflammatory chemokine expression, but an absence of plaque development, in uninvolved skin. Along with our previous observations of the ability of epidermally expressed transgenic D6 to impair cutaneous inflammatory responses, our data support a role for elevated D6 levels in suppressing inflammatory chemokine action and lesion development in uninvolved psoriatic skin. D6 expression consistently dropped in perilesional and lesional skin, coincident with development of psoriatic plaques. D6 expression in uninvolved skin also was reduced after trauma, indicative of a role for trauma-mediated reduction in D6 expression in triggering lesion development. Importantly, D6 is also elevated in peripheral blood leukocytes in psoriatic patients, indicating that upregulation may be a general protective response to inflammation. Together our data demonstrate a novel role for D6 as a regulator of the transition from uninvolved to lesional skin in psoriasis

    Exploring the Life Course Perspective in Maternal and Child Health through Community-Based Participatory Focus Groups: Social Risks Assessment

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    Little is known about the patterns of risk factors experienced by communities of color and how diverse community contexts shape the health trajectory of women from the early childhood period to the time of their pregnancies. Thus, we conducted a focus group study to identify social risks over the life course that contribute to maternal and child health from the perspective of community members residing in low income urban areas. Ten community-based participatory focus groups were conducted with residents from selected communities in Tampa, Florida, from September to November 2013. We used the life course perspective to illuminate and explain the experiences reported by the interviewees. A total of 78 residents participated in the focus groups. Children and adolescents’ health risks were childhood obesity, lack of physical activity, and low self-esteem. Women’s health risks were low self-esteem, low educational level, low health literacy, inadequate parenting skills, and financial problems. Risks during pregnancy included stress, low self-esteem, inadequate eating patterns, lack of physical activity, healthcare issues, lack of social support, and lack of father involvement during pregnancy. Multiple risk factors contribute to maternal and child health in low income communities in Tampa Bay. The intersection of risk factors in different life periods suggest possible pathways, cumulative, and latent effects, which must be considered in future longitudinal studies and when developing effective maternal and child health programs and policies

    Testing cosmological variability of the proton-to-electron mass ratio using the spectrum of PKS 0528-250

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    Multidimensional cosmologies allow for variations of fundamental physical constants over the course of cosmological evolution, and different versions of the theories predict different time dependences. In particular, such variations could manifest themselves as changes of the proton-to-electron mass ratio \mu=m_p/m_e over the period of ~ 10^{10} years since the moment of formation of high-redshift QSO spectra. Here we analyze a new, high-resolution spectrum of the z=2.81080 molecular hydrogen absorption system toward the quasar PKS 0528-250 to derive a new observational constraint to the time-averaged variation rate of the proton-to-electron mass ratio. We find |\dot{\mu} / \mu| < 1.5 \times 10^{-14}/year, which is much tighter than previously measured limits.Comment: 9 pages, 2 tables, 3 figures, LaTeX (aas2pp4.sty and epsf.sty included). To be published in Ap
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