Relaxation of surface charge on rotating dielectric spheres: Implications on dynamic electrorheological effects

We have examined the effect of an oscillatory rotation of a polarized dielectric particle. The rotational motion leads to a re-distribution of the polarization charge on the surface of the particle. We show that the time averaged steady-state dipole moment is along the field direction, but its magnitude is reduced by a factor which depends on the angular velocity of rotation. As a result, the rotational motion of the particle reduces the electrorheological effect. We further assume that the relaxation of polarized charge is arised from a finite conductivity of the particle or host medium. We calculate the relaxation time based on the Maxwell-Wagner theory, suitably generalized to include the rotational motion. Analytic expressions for the reduction factor and the relaxation time are given and their dependence on the angular velocity of rotation will be discussed.Comment: Accepted for publications by Phys. Rev.

The CHARA Array Angular Diameter of HR 8799 Favors Planetary Masses for Its Imaged Companions

HR 8799 is an hF0 mA5 gamma Doradus, lambda Bootis, Vega-type star best known for hosting four directly imaged candidate planetary companions. Using the CHARA Array interferometer, we measure HR 8799's limb-darkened angular diameter to be 0.342 +/- 0.008 mas; this is the smallest interferometrically measured stellar diameter to date, with an error of only 2%. By combining our measurement with the star's parallax and photometry from the literature, we greatly improve upon previous estimates of its fundamental parameters, including stellar radius (1.44 +/- 0.06 R_Sun), effective temperature (7193 +/- 87 K, consistent with F0), luminosity (5.05 +/- 0.29 L_Sun), and the extent of the habitable zone (1.62 AU to 3.32 AU). These improved stellar properties permit much more precise comparisons with stellar evolutionary models, from which a mass and age can be determined, once the metallicity of the star is known. Considering the observational properties of other lambda Bootis stars and the indirect evidence for youth of HR 8799, we argue that the internal abundance, and what we refer to as the effective abundance, is most likely near-solar. Finally, using the Yonsei-Yale evolutionary models with uniformly scaled solar-like abundances, we estimate HR 8799's mass and age considering two possibilities: 1.516 +0.038/-0.024 M_Sun and 33 +7/-13 Myr if the star is contracting toward the zero age main-sequence or 1.513 +0.023/-0.024 M_Sun and 90 +381/-50 Myr if it is expanding from it. This improved estimate of HR 8799's age with realistic uncertainties provides the best constraints to date on the masses of its orbiting companions, and strongly suggests they are indeed planets. They nevertheless all appear to orbit well outside the habitable zone of this young star.Comment: Accepted for publication in ApJ; 37 pages, 6 tables, 13 figure

A non perturbative approach of the principal chiral model between two and four dimensions

We investigate the principal chiral model between two and four dimensions by means of a non perturbative Wilson-like renormalization group equation. We are thus able to follow the evolution of the effective coupling constants within this whole range of dimensions without having recourse to any kind of small parameter expansion. This allows us to identify its three dimensional critical physics and to solve the long-standing discrepancy between the different perturbative approaches that characterizes the class of models to which the principal chiral model belongs.Comment: 5 pages, 1 figure, Revte

Urban-Rural Dependencies and Opportunities to Design Nature-Based Solutions for Resilience in Europe and China

This is the final version. Available on open access from MDPI via the DOI in this recordData Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article.Interrelationships between urban and rural areas are fundamental for the development and safeguarding of viable future living conditions and quality of life. These areas are not well-delineated or self-sufficient, and existing interrelations may privilege one over the other. Major urban challenges facing China and Europe are related to changes in climate, environment, and to decision-making that makes urban and rural landscapes more susceptible to environmental pressures. Focusing on the six European and Chinese cities and surrounding rural areas, under study in the joint EC and MOST-funded REGREEN project, we examine how nature-based solutions (NBS) may assist in counteracting these pressures. We explore urban-rural dependencies and partnerships regarding NBS that can enhance resilience in Europe and China. We analyse differences between European and Chinese systems of governance, reflecting on the significance of the scale of research needed to understand how NBS provide benefits. We highlight interactions between differently delineated sheds (watershed, airshed, natureshed, and peopleshed), which influence the interrelationships between urban and rural areas. There may be one-way or two-way interdependence, and the impact may be uni or multi-directional. The European and Chinese solutions, exemplified in this article, tackle the nexus of environmental and peoplesheds. We discuss complex human interactions (and how to model them) that may, or may not, lead to viable and equitable partnerships for implementing NBS in cities within Europe and in China.European Union Horizon 2020National Key R&D Program Intergovernmental Cooperation in International Science and Technology Innovation, Ministry of Science and Technology of Chin

Stellar Diameters and Temperatures II. Main Sequence K & M Stars

We present interferometric diameter measurements of 21 K- and M- dwarfs made with the CHARA Array. This sample is enhanced by literature radii measurements to form a data set of 33 K-M dwarfs with diameters measured to better than 5%. For all 33 stars, we compute absolute luminosities, linear radii, and effective temperatures (Teff). We develop empirical relations for \simK0 to M4 main- sequence stars between the stellar Teff, radius, and luminosity to broad-band color indices and metallicity. These relations are valid for metallicities between [Fe/H] = -0.5 and +0.1 dex, and are accurate to ~2%, ~5%, and ~4% for Teff, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity dependent transformations to convert colors into stellar Teffs, radii, and luminosities. We find no sensitivity to metallicity on relations between global stellar properties, e.g., Teff-radius and Teff-luminosity. Robust examinations of single star Teffs and radii compared to evolutionary model predictions on the luminosity-Teff and luminosity-radius planes reveals that models overestimate the Teffs of stars with Teff < 5000 K by ~3%, and underestimate the radii of stars with radii < 0.7 R\odot by ~5%. These conclusions additionally suggest that the models overestimate the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for single stars to those of eclipsing binaries, we find that single and binary star radii are consistent. However, the literature Teffs for binary stars are systematically lower compared to Teffs of single stars by ~ 200 to 300 K. Lastly, we present a empirically determined HR diagram for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system. [abridged]Comment: 73 pages, 12 Tables, 18 Figures. Accepted for publication in The Astrophysical Journa

Crop Updates 2005 Oilseeds

This session covers fifteen papers from different authors: 1. ACKNOWLEDGEMENTS, Douglas Hamilton, FARMING SYSTEMS DEVELOPMENT OFFICER CROP AGRONOMY AND NUTRITION 2. Canola workshop at Crop Updates 2005, Oilseeds WA, John Duff, EXECUTIVE OFFICER OILSEEDS WA 3. Comparison of IT and TT canola varieties in geographic zones of WA, 2003-4, Graham Walton and Hasan Zaheer, Department of Agriculture 4. Farmer scale canola variety trials in WA, 2004, Graham Walton, John Duff, Neil Harris and Heather Cosgriff, Oilseeds WA 5. Oilseed crops for industrial uses, Margaret C. Campbell, Centre for Legumes in Mediterranean Agriculture (CLIMA), Graham Walton,Department of Agriculture 6. Weed control opportunities with GM canola, Bill Crabtree, Independent Consultant, Northam 7. Soil and tissue tests for the sulfur requirements of canola, R.F. Brennan and M.D.A. Bolland, Department of Agriculture 8. Tests to predict the potassium requirements of canola, R.F. Brennan and M.D.A. Bolland, Department of Agriculture 9. Genotypic variation in potassium efficiency of canola, P.M. Damon and Z. Rengel, Faculty of Natural and Agricultural Sciences, UWA 10. Atrazine contamination of groundwater in the agricultural region of Western Australia, Russell Speed1, Neil Rothnie2, John Simons1, Ted Spadek2 and John Moore1;1Department of Agriculture, 2Chemistry Centre (WA) PESTS AND DISEASES 11. Controlling aphids and Beet western yellows virus in canola using imidacloprid seed dressing, Brenda Coutts and Roger Jones; Department of Agriculture 12. Managing sclerotinia in canola, Neil Harris, Dovuro Seeds Western Australia 13. Slugs, the trail of destruction in canola, Neil Harris, Dovuro Seeds Western Australia 14. Blackleg risk assessment and strategies for risk management in canola during 2005 and beyond, Moin Salam, Ravjit Khanguraand Art Diggle, Department of Agriculture 15. Modelling: BRAT – Blackleg Risk Appraisal Tool, Moin Salam, Ravjit KhanguraDepartment of Agricultur

IL-27 Induced by Select Candida spp. via TLR7/NOD2 Signaling and IFN-β Production Inhibits Fungal Clearance

Candida spp. elicit cytokine production downstream of various pathogen recognition receptors (PRRs) including C-type lectin-like receptors (CLRs), Toll-like receptors (TLRs) and nucleotide oligomerisation domain (NOD)-like receptors (NLRs). IL-12 family members, IL-12p70 and IL-23, are important for host immunity against Candida spp. Herein we show that IL-27, another IL-12 family member, is produced by myeloid cells in response to select Candida spp. We demonstrate a novel mechanism for C. parapsilosis-mediated induction of IL-27 in a TLR7-, MyD88- and NOD2-dependent manner. Our data revealed that IFN-β is induced by C. parapsilosis, which in turn signals through the interferon-α/β receptor (IFNAR) and STAT1/2 to induce IL-27. Moreover, IL 27R (WSX-1) deficient mice systemically infected with C. parapsilosis displayed enhanced pathogen clearance compared to WT mice. This was associated with increased levels of pro-inflammatory cytokines in the serum and increased IFN-γ and IL-17 responses in the spleens of IL-27R deficient mice. Thus our data define a novel link between C. parapsilosis, TLR7, NOD2, IFN-β and IL-27 and we have identified an important role for IL-27 in the immune response against C. parapsilosis. Overall these findings demonstrate an important mechanism for the suppression of protective immune responses during infection with C. parapsilosis, which has potential relevance for infections with other fungal pathogens

Erratum: “stellar diameters and temperatures. II. main-sequence K- and M-stars” (2012, ApJ, 757, 112)

Published versio