Six months of mass outflow and inclined rings in the ejecta of V1494 Aql

V1494 Aql was a very fast nova which reached a visual maximum of mv≃ 4.0 by the end of 1999 December 3. We report observations from 4 to 284 d after discovery, including submillimetre- and centimetre-band fluxes, a single MERLIN image and optical spectroscopy in the 410 to 700 nm range. The extent of the radio continuum emission is consistent with a recent lower distance estimate of 1.6 kpc. We conclude that the optical and radio emission arises from the same expanding ejecta. We show that these observations are not consistent with simple kinematical spherical shell models used in the past to explain the rise and fall of the radio flux density in these objects. The resolved remnant structure is consistent with an inclined ring of enhanced density within the ejecta. Optical spectroscopy indicates likely continued mass ejection for over 195 d, with the material becoming optically thin in the visible sometime between 195 and 285 d after outburst

High-Speed Flow and Fuel Imaging Study of Available Spark Energy in a Spray-Guided Direct-Injection Engine and Implications on Misfires

The spark energy transferred under the highly stratified conditions during late injection in a spray-guided spark-ignition direct-injection (SG-SIDI) engine is not well characterized. The impact of high pressures, temperatures, velocities, and variations in local fuel concentration along with temporal and/or spatial variations on spark performance must be better characterized. Previous spark ignition studies have not addressed the full range of conditions that are present in SG-SIDI engines. Therefore, high-speed particle image velocimetry (PIV) experiments are conducted to characterize the spark energy dependence for a wide range of well-defined homogeneous fuel–air equivalence ratios (W50–2.9) and average air velocities (0–8m/s) in an optical SG-SIDI engine. Amoderate dependence of spark energy on equivalence ratio is shown to exist with average values of spark energy increasing by 21 per cent for the equivalence ratio range of W50–2.3. Air injection into the motored engine is used to prepare well-defined flow conditions without the complications of fuel concentration gradients that are present during fuel injection. This allows the study of the effects of velocity, shear strain rate, and vorticity on spark energy. The spark energy increases with velocity at the spark plug. This observation is consistent with findings reported in the literature for low-pressure conditions. A linear increase is shown between shear strain rate and spark energy, while vorticity and spark energy are only weakly correlated. Simultaneous high-speed PIV, planar laser-induced fluorescence, and spark-discharge electrical measurements are also performed in the optical SG-SIDI engine to measure flow properties and fuel concentrations under late injection. Operating parameters are chosen to be near peak indicated mean effective pressure performance, but they occasionally provide a random misfired or partial burned cycle. Misfired cycles occur under stoichiometric-to-lean mixtures and low velocities near the spark plug. The lower spark energies observed under these conditions are in agreement with the observationsmade under well-controlled mixture and flow conditions reported in this study. All mixture conditions found in misfiring and partially burning cycles are within the ignitability range and fall within the general population of all, predominantly well-burning, cycles. There is no predominant impact of shear strain rate and vorticity under late injection operation on misfires and partial burns.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86771/1/Sick7.pd

Crop wild relatives: A manual of in situ conservation

Crop wild relatives (CWR) – plant species that are related to crops – provide a vital pool of genetic variation that can be used in breeding new and better-adapted varieties of crops. These varieties may be resistant to stress, disease, drought and other factors. This book captures the important practical experiences of countries participating in recent research on the topic, and describes them for the wider conservation community. Illustrated by case-studies from four geographical regions, this detailed and comprehensive manual provides relevant information and guidance for the scaling-up of actions targeting CWR conservation around the world

Partial Regularity of solutions to the Four-dimensional Navier-Stokes equations at the first blow-up time

The solutions of incompressible Navier-Stokes equations in four spatial dimensions are considered. We prove that the two-dimensional Hausdorff measure of the set of singular points at the first blow-up time is equal to zero.Comment: 19 pages, a comment regarding five or higher dimensional case is added in Remark 1.3. accepted by Comm. Math. Phy

Variability of the Antarctic slope current system in the northwestern Weddell Sea

The dense water outflow from the Antarctic continental shelf is closely associated with the strength and position of the Antarctic Slope Front. We explore the short-term and spatial variability of the Antarctic Slope Front system and the mechanisms that regulate cross-slope exchange using highly temporallyand spatially-resolved measurements from three ocean gliders deployed in 2012. Twenty-two sections along the eastern Antarctic Peninsula and west of the South Orkney Islands are grouped regionally and composited by isobaths. There is consistency in the front position around the Powell Basin, varying mostly between the 500 and 800m isobaths. In most of the study area the flow is bottom-intensified. The along-slope transport of the Antarctic Slope Current (upper 1000 m) varies between 0.2 and 5.9 Sv and does not exhibit a regional pattern. The magnitude of the velocity field shows substantial variability, up to twice its mean value. Higher eddy kinetic energy (0.003m2 s−2) is observed on sections with dense water, possibly due to baroclinic instabilities in the bottom layer. Distributions of potential vorticity show an increase towards the shelf along isopycnals and also in the dense water layer. Glider sections located west of the South Orkney Islands indicate a northward direction of the flow associated with the Weddell Front, which differs from previous estimates of the mean circulation. This study provides some of the first observational confirmation of the high frequency variability associated with an active eddy field that has been suggested by recent numerical simulations in this region

Parientes silvestres de los cultivos: Manual para la conservación in situ

Los parientes silvestres de los cultivos (PSC) se pueden definir como plantas silvestres más o menos relacionadas con un cultivo. Los PSC representan un recurso genético vital para el fitomejoramiento de variedades nuevas mejoradas, que se necesitan para mantener y aumentar la productividad de nuestros cultivos y para permitirles sobrevivir en las nuevas condiciones creadas por el cambio climático. Hasta hace muy poco, la principal estrategia de conservación adoptada para los parientes silvestres de cultivos ha sido ex situ, mediante el mantenimiento de muestras, incluyendo semillas o material vegetativo, en diversos tipos de bancos de germoplasma u otras instalaciones. Ahora se reconoce que la conservación de los parientes silvestres de cultivos en su ambiente natural (in situ) puede permitir que las poblaciones sigan evolucionando y generen nueva variabilidad genética adaptada a las condiciones cambiantes. Hasta ahora, la experiencia y el conocimiento sobre la conservación in situ de los PSC ha sido muy limitada –un punto que este manual resuelve al mejorar significativamente el cuerpo de conocimiento en el tema. La investigación mencionada en este manual y coordinada por Bioversity International en colaboración con socios nacionales e internacionales ha creado una riqueza de información sobre buenas prácticas y lecciones aprendidas. Incluye experiencias prácticas importantes desde Armenia, Bolivia, Madagascar, Sri Lanka y Uzbekistán - importantes centros de biodiversidad genética de PSC. Contiene información relevante y directrices para replicar las acciones relacionadas con la conservación de los PSC en todo el mundo

The spatial sensitivity of the spectral diversity–biodiversity relationship: an experimental test in a prairie grassland

Remote sensing has been used to detect plant biodiversity in a range of ecosystems based on the varying spectral properties of different species or functional groups. However, the most appropriate spatial resolution necessary to detect diversity remains unclear. At coarse resolution, differences among spectral patterns may be too weak to detect. In contrast, at fine resolution, redundant information may be introduced. To explore the effect of spatial resolution, we studied the scale dependence of spectral diversity in a prairie ecosystem experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Our study involved a scaling exercise comparing synthetic pixels resampled from high-resolution images within manipulated diversity treatments. Hyperspectral data were collected using several instruments on both ground and airborne platforms. We used the coefficient of variation (CV) of spectral reflectance in space as the indicator of spectral diversity and then compared CV at different scales ranging from 1 mm2 to 1 m2 to conventional biodiversity metrics, including species richness, Shannon’s index, Simpson’s index, phylogenetic species variation, and phylogenetic species evenness. In this study, higher species richness plots generally had higher CV. CV showed higher correlations with Shannon’s index and Simpson’s index than did species richness alone, indicating evenness contributed to the spectral diversity. Correlations with species richness and Simpson’s index were generally higher than with phylogenetic species variation and evenness measured at comparable spatial scales, indicating weaker relationships between spectral diversity and phylogenetic diversity metrics than with species diversity metrics. High resolution imaging spectrometer data (1 mm2 pixels) showed the highest sensitivity to diversity level. With decreasing spatial resolution, the difference in CV between diversity levels decreased and greatly reduced the optical detectability of biodiversity. The optimal pixel size for distinguishing a diversity in these prairie plots appeared to be around 1 mm to 10 cm, a spatial scale similar to the size of an individual herbaceous plant. These results indicate a strong scaledependence of the spectral diversity-biodiversity relationships, with spectral diversity best able to detect a combination of species richness and evenness, and more weakly detecting phylogenetic diversity. These findings can be used to guide airborne studies of biodiversity and develop more effective large-scale biodiversity sampling methods

Self-reported testing and treatment histories among older Australian men and women who may be at risk of a sexually transmissible infection

Background: Rates of sexually transmissible infections (STIs) are increasing among older adults in many countries. Little is known about the testing and treatment histories of these populations. Correlates of testing in the past 5 years among older adults who may be at risk of a STI were examined. Methods: A cross-sectional survey of 2137 Australians aged 60+ years that involved questions on STIs and STI testing was conducted in 2015. To help inform potential education campaigns, analyses focused on those who may have been at risk of a STI (n = 805, 38%). Results: Less than one in three reported a STI test in the past 5 years (n = 241, 30%) while 6% (n = 51) reported a STI diagnosis. Those diagnosed typically received treatment from a family doctor or general practitioner. Among men, lower testing rates were associated with older age, identifying as heterosexual, lower educational attainment, not using online dating and reporting one partner in the past 5 years. For women, lower rates of testing were found among those who did not use a condom at their most recent sexual encounter and those with one partner in the past 5 years. Conclusions: STI testing rates were low. This study indicates that consideration should be given to the way targeted education campaigns are formulated, such as emphasising the importance of STI testing to older people who are at risk, as well as encouraging healthcare professionals to discuss sexual health with their older patients

Safer sex in later life: Qualitative interviews with older Australians on their understandings and practices of safer sex

Rates of sexually transmitted infections (STIs) are increasing in older cohorts in Western countries such as Australia, the U.K. and the U.S., suggesting a need to examine the safer sex knowledge and practices of older people. This article presents findings from 53 qualitative interviews from the study “Sex, Age & Me: a National Study of Sex and Relationships Among Australians aged 60+.” Participants were recruited through an online national survey. We consider how participants understood “safer sex,” the importance of safer sex to them, the safer sex practices they used (and the contexts in which they used them), and the barriers to using safer sex. Older adults had diverse understandings, knowledge, and use of safer sex practices, although participants tended to focus most strongly on condom use. Having safer sex was strongly mediated by relationship context, trust, perceived risk of contracting an STI, concern for personal health, and stigma. Common barriers to safer sex included erectile difficulties, embarrassment, stigma, reduced pleasure, and the lack of a safer sex culture among older people. The data presented has important implications for sexual health policy, practice, and education and health promotion campaigns aimed at improving the sexual health and wellbeing of older cohorts