1,494 research outputs found

    XMM-Newton study of 0.012<z<0.024 groups. I: Overview of the IGM thermodynamics

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    We study the thermodynamic properties of the hot gas in a sample of groups in the 0.012-0.024 redshift range, using XMM-Newton observations. We present measurements of temperature, entropy, pressure and iron abundance. Non-parametric fits are used to derive the mean properties of the sample and to study dispersion in the values of entropy and pressure. The scaling of the entropy at 0.2r500 matches well the results of Ponman et al. (2003). However, compared to cool clusters, the groups in our sample reveal larger entropy at inner radii and a substantially flatter slope in the entropy in the outskirts, compared to both the prediction of pure gravitational heating and to observations of clusters. This difference corresponds to the systematically flatter group surface brightness profiles, reported previously. The scaled pressure profiles can be well approximated with a Sersic model with n=4. We find that groups exhibit a systematically larger dispersion in pressure, compared to clusters of galaxies, while the dispersion in entropy is similar.Comment: 11 pages, MNRAS in press, the 25 page version with all 176 figures included is at ftp://ftp.xray.mpe.mpg.de/people/alexis/2dxgs_astroph.ps.g

    ‘All in all it is just a judgement call’: issues surrounding sexual consent in young people’s heterosexual encounters

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    In the UK, there has been growing concern about young people’s understanding of sexual consent, with the views of young people themselves often lost in academic and educational policy debates. However, the focus on high rates of sexual violence has meant a lack of attention on the everyday negotiation of consensual heterosexual activity, leading to assumptions being made regarding young people’s lack of understanding of sexual consent. This paper emerges from a wider study of over 500 young people which sought to uncover their understanding of the issues. Drawing on data from workshops and the open text responses to an on-line survey the findings presented in this paper show that the majority of heterosexual young people understood the complexity of sexual consent as an embodied process, which can be difficult to define, talk about or practice uniformly. This complex understanding, in which sexual consent is a continuum rather than a dichotomy, has implications for sexual education initiatives. We argue that it is only by providing a closer understanding of how - within consensual sexual activities - young people understand and enact sexual consent through a range of embodied communication strategies that education surrounding sexual assault will become meaningful

    Photorespiration: metabolic pathways and their role in stress protection

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    Photorespiration results from the oxygenase reaction catalysed by ribulose-1,5-bisphosphate carboxylase/ oxygenase. In this reaction glycollate-2-phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate-3-phosphate. During this metabolic process, CO2 and NH3 are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this ine¤ciency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants

    Modelling and nanofabrication of chiral dielectric metasurfaces

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    Polarization control through all-dielectric metasurfaces holds great potential in different fields, such as telecommunications, biochemistry and holography. Asymmetric chiral metasurfaces supporting quasi-bound states in the continuum may prove very useful for controlling and manipulating the polarization state of light. A crucial quantity for characterizing the optical chirality is the circular dichroism (CD). In this work we analyse how the CD and quality factor of the optical mode can be strongly influenced by a nanofabrication error. Modelling the nanofabrication uncertainties on the gaps of the chiral metasurface, the imperfections of the etchings process or the modification of the asymmetry factor, we found that the proper engineering of the gap between the nanostructures of the unit cell is the most important parameter to achieve a high-quality factor and enhanced optical dichroism. An optimization of the nanofabrication processes, such as dose factor, dwell time and plasma etching demonstrates that, for a writing field of 100 & mu;m2, it is possible to obtain morphologically precise chiral metasurfaces, with fabrication uncertainties lower than those that would limit Q factor and chirality property

    Community awareness of green roofs in Sydney

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    There are environmental, economic and social benefits of installing green roofs and walls on city buildings. The environmental benefits are lower building related operational carbon emissions, reductions in the urban heat island, increases in bio-diversity and reductions in storm-water run-off. Economically, the benefits are reduced roof maintenance costs, lower running costs, higher capital and rental values for commercial buildings. Finally the social or community gains are the creation of aesthetically pleasing spaces, landmarksand cultural capital as well as provision of recreational spaces. Furthermore social, psychological and therapeutic gains accrue when the roof or wall is visible to people andis used for social interaction and leisure activities. The perceived drawbacks are perceived greater risk of building leaks, high costs of installation and maintenance, and access and security issues. Whilst the technology to design and install green roofs and walls has existed for hundreds of years the uptake and the demand for green roofs and walls has not been high. Overall, the environmental social and economic gains are not perceived sufficient to create significant demand to set up green roofs and walls. In Sydney Australia, the existing number of green roofs and walls are testimony to this observation. With the aim of addressing the barriers to the uptake of green roofs and walls; it is essential to understand the way in which the key stakeholders; here the community, perceive the technology. With this knowledge it is then feasible to develop an agenda to mitigate any erroneous perceptions that exists. This research reports on a survey with the Sydney community to determine their perceptions of green roofs and walls

    Nanopatterned Graphene on a Polymer Substrate by a Direct Peel-off Technique

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    : A graphene (Gr) on a polyimide (PI) polymer film (Gr−PI film), obtained by a direct peel-off technique, is proposed and investigated. Thanks to its high transparency, electrical conductivity, mechanical strength, and chemical durability, the Gr−PI film is an ideal substrate for flexible electronic and optoelectronic devices, including transistors, lightemitting diodes, and plasmonic antennas. It is obtained using a straightforward method. After spin coating and curing a PI film on Gr previously grown on Cu, one can separate the Gr−PI film from the Cu foil thanks to the difference in the adhesive energy between the Gr−Cu and Gr−PI interfaces. The resulting Gr−PI film shows an average electrical sheet resistance ranging from 520 to 860 Ω/sq and a very high optical transmission (>90%), which have allowed the demonstration of a transparent heater. The surface morphology of the Gr−PI film follows that of the Cu foil, with the latter maintaining its surface properties and allowing in this way its reuse in subsequent chemical vapor deposition growth. The mePeer ReviewedPostprint (author’s final draft

    Childhood growth predicts higher bone mass and greater bone area in early old age : findings among a subgroup of women from the Helsinki Birth Cohort Study

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    We examined the associations between childhood growth and bone properties among women at early old age. Early growth in height predicted greater bone area and higher bone mineral mass. However, information on growth did not improve prediction of bone properties beyond that predicted by body size at early old age. We examined the associations between body size at birth and childhood growth with bone area, bone mineral content (BMC), and areal bone mineral density (aBMD) in early old age. A subgroup of women (n = 178, mean 60.4 years) from the Helsinki Birth Cohort Study, born 1934-1944, participated in dual-energy X-ray absorptiometry (DXA) measurements of the lumbar spine and hip. Height and weight at 0, 2, 7, and 11 years, obtained from health care records, were reconstructed into conditional variables representing growth velocity independent of earlier growth. Weight was adjusted for corresponding height. Linear regression models were adjusted for multiple confounders. Birth length and growth in height before 7 years of age were positively associated with femoral neck area (p <0.05) and growth in height at all age periods studied with spine bone area (p <0.01). Growth in height before the age of 7 years was associated with BMC in the femoral neck (p <0.01) and birth length and growth in height before the age of 7 years were associated with BMC in the spine (p <0.05). After entering adult height into the models, nearly all associations disappeared. Weight gain during childhood was not associated with bone area or BMC, and aBMD was not associated with early growth. Optimal growth in height in girls is important for obtaining larger skeleton and consequently higher bone mass. However, when predicting bone mineral mass among elderly women, information on early growth does not improve prediction beyond that predicted by current height and weight.Peer reviewe

    Transgenic camelina oil is an effective source of eicosapentaenoic acid and docosahexaenoic acid in diets for farmed rainbow trout, in terms of growth, tissue fatty acid content, and fillet sensory properties

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    The oilseed Camelina sativa was genetically engineered to produce eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to fish oil (FO), which we tested as a lipid source in diets for rainbow trout. Three experimental diets were tested, a FO control, a low‐level transgenic camelina oil (LCO) diet (no FO with 12.5 g/kg camelina), and a high‐level transgenic camelina oil (HCO) diet (no FO with 130 g/kg transgenic camelina). Trout (initial weight 49.8 ± 11 g/fish) were fed for 12 weeks and were evaluated for growth performance, fatty acid content (muscle, liver, brain, and eye), and sensory properties of fillets. The final lengths and weights of fish fed LCO and HCO diets were higher compared to fish fed FO. There were no differences in weight gain, condition factor, specific growth rate, feed intake, and feed conversion ratio. EPA in muscle tissue was higher in fish fed HCO and FO diets compared to the LCO diet. Compound‐specific stable isotope analysis revealed that rainbow trout fed the FO diet stored isotopically enriched DHA compared to the lighter DHA in fish fed HCO. Trout fillets from the HCO treatment were firmer in texture and had a higher orange intensity compared to the FO group

    Behaviour of uranium along Jucar River (Eastern Spain) Determination of 234U/238U and 235U/238U ratios

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    The uranium concentration and the U-234/U-238, U-235/U-238 activity ratios were studied in water samples from Jucar River, using low-level alpha-spectrometry. The effects of pH, temperature and salinity were considered and more detailed sampling was done in the neighbourhood of Cofrentes Nuclear plant (Valencia, Spain). Changes were observed in the uranium concentration with the salinity and the U-234/U-238 activity ratio was found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes in the concentration of uranium and the activity ratios.Rodríguez Álvarez, MJ.; Sanchez, F. (1995). Behaviour of uranium along Jucar River (Eastern Spain) Determination of 234U/238U and 235U/238U ratios. Journal of Radioanalytical and Nuclear Chemistry. 190(1):113-120. doi:10.1007/BF02035642S1131201901M. J. RORDÍGUEZ-AALVAREZ, F. SÁNCHEZ, E. NAVARRO, Proc. 3nd Intern. Summer School, Huelva Spain, M. GARCÍA-LEÓN, G. MADURGA (Eds), World Scientific, Singapore, 1994.M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.K. OSMOND, J. B. COWART, At. Energy Rev., 14 (1976) 621.B. L. DICKSON, R. L. MEAKINS, Nucl. Instrum. Methods Phys. Res., 223 (1983) 593.J. L. GASCÓN, MURILLO, PhD Thesis, University of Zaragoza, Spain, 1990.M. C. MORÓN, A. MARTINEZ-AGUIRRE, M. GARCÍA-LEÓN, Intern. Conf. on Environmental Radioactivity in the Mediterranean Area, Barcelona 10–13 May 1988, SNE-ENS, Barcelona, 1988, p. 111.R. BOJANOWSKI, R. FUKAI, S. BALLESTRA, H. ASARI, Determination of natural radioactive elements in marine environmental materials by ion-exchange and α-spectrometry. Proc. 4th Symp. on the Determination of Radionuclides in Environmental and Biological Materials, April 1983, London, Ed-Rd Press.R. GARCÍA-TENORIO, M. GARCÍA-LEÓN, G. PIAZZA, Anal. Física B, 82 (1986) 238.L. HALLSTADIUS, Nucl. Instrum. Methods Phys. Res., 223 (1984) 266.F. VERA, A. MARTIN, Nucl. Instrum. Methods Phys. Res., A276 (1989) 289.A. MARTINEZ-AGUIRRE, M. GARCÍA-LEÓN, J. Radioanal. Nucl. Chem., 155 (1991) 97.J. R. DOOLEY, H. C. ROSHOLT, Econ. Geol., 61 (1996) 326.A. MARTINEZ-AGUIRRE, M. GARCÍA-LEÓN, Radiat. Prot. Dosim., 45 (1992) 249.J. TOOLE, M. S. BAXTER, J. THOMSON, Estuarine, Coastal and Shelf Sci., 25 (1987) 283.S. G. BHAT, S. KRISHANASWAMI, Proc. Indian Acad. Sci., A LXX, (1969).K. K. TUREKIAN, J. K. COCHRAN, in: Chemical Oceanography, Vol. 7, J. P. RILEY and R. CHESTER (Eds), 2nd ed., Academic Press, New York, 1978.D. LANGMUIR, Geochim. Cosmochim. Acta, 42 (1978) 547.J. M. MARTIN, M. MEYBECK, Mar. Chem., 7 (1979) 173.Radionuclide Transformations, Annals of the ICRP, ICRP Publication 38, Vol. 11–13, Pergamon Press, 1983.A. MANGINI, G. SONNTAG, G. BERTSCH, E. MÜLLER, Nature, 278 (1979) 337.M. R. SCOTT, in: M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.J. K. OSMOND, J. B. COWART, in: M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.R. BOWEN (Eds), Isotopes in the Earth Sciences, Elsevier Applied Science, 1988.F. VERA, PhD Thesis, University Extremadura, Spain, 1988.F. VERA, A. MARTIN, J. Radioanal. Nucl. Chem., 134 (1988) 73

    Can rates of ocean primary production and biological carbon export be related through their probability distributions?

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    © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Global Biogeochemical Cycles 32 (2018): 954-970, doi:10.1029/2017GB005797.We describe the basis of a theory for interpreting measurements of two key biogeochemical fluxes—primary production by phytoplankton (p, μg C · L−1 · day−1) and biological carbon export from the surface ocean by sinking particles (f, mg C · m−2 · day−1)—in terms of their probability distributions. Given that p and f are mechanistically linked but variable and effectively measured on different scales, we hypothesize that a quantitative relationship emerges between collections of the two measurements. Motivated by the many subprocesses driving production and export, we take as a null model that large‐scale distributions of p and f are lognormal. We then show that compilations of p and f measurements are consistent with this hypothesis. The compilation of p measurements is extensive enough to subregion by biome, basin, depth, or season; these subsets are also well described by lognormals, whose log‐moments sort predictably. Informed by the lognormality of both p and f we infer a statistical scaling relationship between the two quantities and derive a linear relationship between the log‐moments of their distributions. We find agreement between two independent estimates of the slope and intercept of this line and show that the distribution of f measurements is consistent with predictions made from the moments of the p distribution. These results illustrate the utility of a distributional approach to biogeochemical fluxes. We close by describing potential uses and challenges for the further development of such an approach.National Science Foundation Grant Number: OCE-1315201; Simons Foundation Grant Numbers: 329108, 553242; National Aeronautics and Space Administration Grant Numbers: NNX16AR47G, NNX16AR49
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