High spectral resolution time-resolved optical spectroscopy of V893 Sco

We present high resolution time-resolved optical spectra of the high inclination short orbital period dwarf nova V893 Sco. We performed spectral analysis through radial velocity measurements, Doppler mapping, and ratioed Doppler maps. Our results indicate that V893 Sco's accretion disk is dissimilar to WZ Sge's accretion disk, and does not fit any of the current accretion disk models. We derive the system parameters M1 and i, and present evidence for V893 Sco as a very young cataclysmic variable and an ER UMa star. We advance the hypothesis that all ER UMa stars may be newly formed cataclysmic variables.Comment: 23 pages (total), 8 figures, accepted by Ap

Orbit-resolved photometry and echelle spectroscopy of the cataclysmic variable ST LMi during a 2007 high state

We present high-resolution echelle spectra and contemporaneous photometry of the polar ST LMi during a high state in 2007 March. Emission lines at Hα, He I λ5876, and He I λ7065 show similar line profiles over orbital phase and have narrow and broad components. These profile changes with phase are very similar to those reported in earlier high-state studies of ST LMi. The radial velocity curves from double Gaussian fits to the line profiles are interpreted as two crossing curves, neither of which is coincident with the orbital motion of the secondary star. We attribute one component to infall motions near the white dwarf and the other to a gas streaming along magnetic field lines connecting the two stars

The influence of rootstock on the cold-hardiness of Seyval grapevines 1. Primary and secondary effects on growth, canopy development, yield, fruit quality and cold hardiness

Primary (direct) and secondary (indirect) influences of rootstocks on vine cold hardiness were determined independently. Vine size (kg of cane prunings per vine) reflects the number of shoots produced per m of row and is closely associated with shoot crowding and internal canopy shading. This shading is a secondary rootstock influence.Own-rooted Seyval (Sey/own), Seyval grafted to Seyval (Sey/Sey), Kober 5 BB (Sey/5 BB), and Couderc 3309 (Sey/3309) were the rootstock treatments used. Vine size classes were large (1.82-2.27 kg), medium (1.14-1.59 kg) and small (0.45-0.91 kg) and were established within each rootstock group.Rootstock choice had no effect on vine growth and canopy development. Vine productivity was influenced slightly, primarily through differences in cluster weight. By contrast, vine size, regardless of rootstock chosen, had a great impact on both vine growth and yield.Direct rootstock effects on cold hardiness were assessed via measurement of cumulative injury to buds and expressed as shootless nodes. Cane cold hardiness was based on the within-vine distribution of canes with differing characteristics associated with hardiness (diameter, exposure to sunlight during growth and the development of 5 or more mature nodes).Both primary and secondary influences of rootstocks on cold hardiness were observed. Bud hardiness was best on scions grafted to Couderc 3309, and there was a significant graft union effect; Sey/own vines had more bud mortality than Sey/Sey vines. Vine size did not influence the percentage of shootless nodes when canes of comparable quality were evaluated. The within-vine distribution of cane quality was influenced, however, and large vines had a greater number of both poorly matured and canes with superior hardiness status. By contrast, rootstock did not influence the within-vine distribution of cane quality.Large vines are not inferior to small vines in the number of best quality canes produced and should be equally hardy if careful cane selection is practiced at pruning.Assessment of the within-vine distribution of canes with superior cold hardiness appears to be a useful method of determining secondary treatment effects on vine cold hardiness. This aspect of vine cold hardiness should receive greater attention by viti-culture researchers.Einßuß der Unterlage auf die Kälteresistenz der Rebsorte Seyval1. Primärer und sekundärer Einfluß auf Wuchsstärke, Dichte der Laubwand, Ertrag, Traubenqualität und FrosthärteDer Einfluß der Unterlage und der Wuchsleistung (kg Schnittholz je Rebe) auf die Kälteresistenz der Sorte Seyval wurden getrennt untersucht. In dem Unterlagenversuch wurden folgende Varianten geprüft: Wurzelechte Seyval-Reben (Sey/own). Seyval auf Seyval gepfropft (Sey/Sey), Kober 5 BB (Sey/5 BB), und Couderc 3309 (Sey/3309). Die Reben jeder Unterlagenvariante wurden in drei Wuchsklassen - stark, mittel und schwach eingeteilt. Die Wirkung der Unterlage auf die Kälteresistenz wurde in Form der gesamten Knospenschädigung (Prozent tote Knospen) erfaßt. Als weiteres Merkmal für die Frosthärte diente die Qualität der Triebe innerhalb einer Rebe: mittlerer Triebdurchmesser und gute Exposition zur Sonne während der Vegetationsperiode.Die verwendete Unterlage hatte keinen Einfluß auf das Wachstum der Reben und die Entwicklung der Laubwand. Der Traubenertrag wurde nur schwach, in erster Linie über das Traubengewicht, beeinflußt. Im Unterschied hierzu wirkte sich die Größe einer Rebe, unabhängig von der Unterlage, maßgeblich auf das Wachstum und den Ertrag aus.Die Frosthärte hängt sowohl von Primär- wie Sekundäreinflüssen der Unterlage ab. Von allen Kombinationen wiesen die Sey/3309-Reben den geringsten Prozentsatz toter Knospen auf. Die Wuchsgröße beeinflußte den Ausfall von Knospen nicht signifikant, wenn Triebe gleicher Qualität beurteilt wurden. Die Unterlage beeinflußte ebenfalls nicht die Qualität der Triebe innerhalb einer Rebe.Starkwüchsige Reben hatten sowohl eine größere Anzahl schlecht ausgereifter Triebe als auch mehr reife Triebe mit guter Frosthärte. Starke Reben scheinen nicht weniger kälteresistent zu sein als schwächer wachsende, sofern beim Rebschnitt eine sorgfältige Auswahl der Tragruten getroffen wird

Macroscopic modelling of the surface tension of polymer-surfactant systems

Polymer-surfactant mixtures are increasingly being used in a wide range of applications. Weakly-interacting systems, such as SDS/PEO and SDS/PVP, comprise ionic surfactants and neutral polymers, while strongly-interacting systems, such as SDS/POLYDMDAAC and C12TAB/NaPSS, comprise ionic surfactants and oppositely charged ionic polymers. The complex nature of interactions in the mixtures leads to interesting and surprising surface tension profiles as the concentrations of polymer and surfactant are varied. The purpose of our research has been to develop a model to explain these surface tension profiles and to understand how they relate to the formation of different complexes in the bulk solution. In this paper we shouw how an existing model based on the law of mass action can be extended to model the surface tension of weakly-interacting systems, and we also extend it further to produce a model for the surface tension of strongly interacting systems. Applying the model to a variety of strongly-interacting systems gives remarkable agreement with the experimental results. The model provides a sound theoretical basis for comparing and contrasting the behaviour of different systems and greatly enhances our understanding of the features observed

Infrared spectroscopy of cataclysmic variables: III. Dwarf novae below the period gap and novalike variables

We present K-band spectra of the short-period dwarf novae YZ Cnc, LY Hya, BK Lyn, T Leo, SW UMa and WZ Sge, the novalike variables DW UMa, V1315 Aql, RW Tri, VY Scl, UU Aqr and GP Com, and a series of field dwarf stars with spectral types ranging from K2-M6. The spectra of the dwarf novae are dominated by emission lines of HI and HeI. The large velocity and equivalent widths of these lines, in conjunction with the fact that the lines are double-peaked in the highest inclination systems, indicate an accretion disc origin. In the case of YZ Cnc and T Leo, for which we obtained time-resolved data covering a complete orbital cycle, the emission lines show modulations in their equivalent widths which are most probably associated with the bright spot (the region where the gas stream collides with the accretion disc). There are no clear detections of the secondary star in any of the dwarf novae below the period gap, yielding upper limits of 10-30% for the contribution of the secondary star to the observed K-band flux. In conjunction with the K-band magnitudes of the dwarf novae, we use the derived secondary star contributions to calculate lower limits to the distances to these systems. The spectra of the novalike variables are dominated by broad, single-peaked emission lines of HI and HeI - even the eclipsing systems we observed do not show the double-peaked profiles predicted by standard accretion disc theory. With the exception of RW Tri, which exhibits NaI, CaI and 12CO absorption features consistent with a M0V secondary contributing 65% of the observed K-band flux, we find no evidence for the secondary star in any of the novalike variables. The implications of this result are discussed.Comment: 13 pages, 5 figures, to appear in MNRA

Accountability and legitimacy of NGOs under authoritarianism: the case of China

How non-governmental organisations (NGOs) craft accountability and legitimacy in authoritarian states is poorly understood. We put forward a framework of analysis for capturing the processes of making accountability and legitimacy. We introduce the ideas of first- and second-order accountability and stocks of accountability capital. In authoritarian regimes, building second-order accountability through the accumulation of stocks of accountability is crucial for NGOs’ survival and organisational development and as a path towards gaining first-order accountability. Drawing on a decade of fieldwork on child welfare NGOs in China from 2007 to 2017, we select three case studies with long operational trajectories to illustrate processes of crafting legitimacy and accountability. The research contributes empirically and theoretically to the understanding of accountability in NGOs in authoritarian states through the novel analytic framework and case study of China

Adaptive Optics Images of Kepler Objects of Interest

All transiting planets are at risk of contamination by blends with nearby, unresolved stars. Blends dilute the transit signal, causing the planet to appear smaller than it really is, or produce a false positive detection when the target star is blended with eclipsing binary stars. This paper reports on high spatial-resolution adaptive optics images of 90 Kepler planetary candidates. Companion stars are detected as close as 0.1 arcsec from the target star. Images were taken in the near-infrared (J and Ks bands) with ARIES on the MMT and PHARO on the Palomar Hale 200-inch. Most objects (60%) have at least one star within 6 arcsec separation and a magnitude difference of 9. Eighteen objects (20%) have at least one companion within 2 arcsec of the target star; 6 companions (7%) are closer than 0.5 arcsec. Most of these companions were previously unknown, and the associated planetary candidates should receive additional scrutiny. Limits are placed on the presence of additional companions for every system observed, which can be used to validate planets statistically using the BLENDER method. Validation is particularly critical for low-mass, potentially Earth-like worlds, which are not detectable with current-generation radial velocity techniques. High-resolution images are thus a crucial component of any transit follow-up program.Comment: 9 pages, 4 figures, accepted to A

Optically excited states in positronium

Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium

Simultaneous X-ray and Optical Observations of EX Hydrae

The intermediate polar, EX Hydrae, was the object of a large simultaneous multiwavelength observational campaign during 2000 May - June. Here we present the Rossi X-ray Timing Explorer photometry and optical photometry and spectroscopy from ground-based observatories obtained as part of this campaign. Balmer line radial velocities and Doppler maps provide evidence for an extended bulge along the outer edge of the accretion disk and some form of extended/overflowing material originating from the hot spot. In addition, the optical binary eclipse possesses an extended egress shoulder, an indication that an additional source (other than the white dwarf) is coming out of eclipse. We also compare the X-ray and optical results with the results obtained from the EUV and UV observations from the multiwavelength data set.Comment: to appear in the Astronomical Journal, April 200