The effect of drought stress on the green spruce aphid

The green spruce aphid, Elatobium abietinum (Walker) (Hemiptera: Aphididae), is the most important defoliating pest of Sitka spruce, Picea sitchensis (Bong.) Carr., in the U.K. Currently, populations of this aphid are limited by freezing periods in the winter, while interactions between climate and other factors regulate population dynamics. Climate change in the U.K. is predicted to result in: (1) warmer winters, improving overwinter survival by aphid populations, and (2) an increase in hot and dry summers, likely to place Sitka spruce under drought stress. These could promote aphid densities and increased damage to the trees, resulting in losses to plant growth and productivity. Few studies have been conducted on the effect of drought stress on arboreal herbivores. This project sought to explore the effects of different intensities of spring-summer drought stress on E. abietinum on Sitka spruce. Populations and their effects on their host plant, in terms of needle retention and impact on tree growth, were observed in a semi-field nursery setting. The performance of individual aphids was also observed under controlled conditions at intervals following bud-burst in spring, and again in autumn. Finally, a study was conducted on the consumption rates of specialist and generalist Coccinellid predators feeding on aphids reared under differing drought intensities. Elatobium abietinum exhibited an overall positive response to moderate intermittent drought stress, while severe stress was typically detrimental. When considered with aphid size, Coccinellid predator consumption rates reflected these findings. Changes to damage levels on Sitka spruce can therefore be expected under drought stress; increases are likely under moderate intermittent stress, though the nature of changes under severe stress levels remain unclear. The results revealed complex interactions between drought stress, E. abietinum and Sitka spruce. Given the potential impact of the aphid, it is important to understand the possible responses under climate change.Open Acces

The technical and economic benefits of utility sponsored renewable energy integration

In recent years, Australian energy consumers have begun to install large amounts of distributed generation (DG), particularly residential solar photovoltaic (PV) systems. This rapid increase in DG, has led to the flow of power throughout low voltage (LV) networks to become bidirectional. This reverse power flow, along with the intermittent nature of solar PV and the inability for distribution network service providers (DNSPs) to control where this DG is installed, has led to voltage regulation issues throughout LV networks. Along with solar PV, energy storage (ES) is also becoming more prevalent among energy consumers. The combination of solar PV and ES allows customers to become more energy independent, relying less on utilising energy from the grid. This poses a major risk to DNSPs who rely on the income generated from customers based on kWh sales to build and maintain network infrastructure. This paper presents a coordinated reactive power control scheme to reduce voltage rise along LV distribution feeders with high penetrations of solar PV. The value of privately investing in solar PV and ES for the years 2015 and 2020 from the perspective of an average residential customer is determined. Finally, a business model is proposed outlining how utility sponsored residential solar PV and ES could be implemented by a DNSP. The business model is then evaluated from a technical and economic standpoint

Radio galaxies and their magnetic fields out to z <= 3

We present polarisation properties at $1.4\,$GHz of two separate extragalactic source populations: passive quiescent galaxies and luminous quasar-like galaxies. We use data from the {\it Wide-Field Infrared Survey Explorer} data to determine the host galaxy population of the polarised extragalactic radio sources. The quiescent galaxies have higher percentage polarisation, smaller radio linear size, and $1.4\,$GHz luminosity of $6\times10^{21}<L_{\rm 1.4}<7\times10^{25}\,$W Hz$^{-1}$, while the quasar-like galaxies have smaller percentage polarisation, larger radio linear size at radio wavelengths, and a $1.4\,$GHz luminosity of $9\times10^{23}<L_{\rm 1.4}<7\times10^{28}\,$W Hz$^{-1}$, suggesting that the environment of the quasar-like galaxies is responsible for the lower percentage polarisation. Our results confirm previous studies that found an inverse correlation between percentage polarisation and total flux density at $1.4\,$GHz. We suggest that the population change between the polarised extragalactic radio sources is the origin of this inverse correlation and suggest a cosmic evolution of the space density of quiescent galaxies. Finally, we find that the extragalactic contributions to the rotation measures (RMs) of the nearby passive galaxies and the distant quasar-like galaxies are different. After accounting for the RM contributions by cosmological large-scale structure and intervening Mg\,{II} absorbers we show that the distribution of intrinsic RMs of the distant quasar-like sources is at most four times as wide as the RM distribution of the nearby quiescent galaxies, if the distribution of intrinsic RMs of the WISE-Star sources itself is at least several rad m$^{-2}$ wide.Comment: 12 pages, 8 figures, accepted for publication into MNRA

Radio Galaxy Zoo: Cosmological Alignment of Radio Sources

We study the mutual alignment of radio sources within two surveys, FIRST and TGSS. This is done by producing two position angle catalogues containing the preferential directions of respectively $30\,059$ and $11\,674$ extended sources distributed over more than $7\,000$ and $17\,000$ square degrees. The identification of the sources in the FIRST sample was performed in advance by volunteers of the Radio Galaxy Zoo project, while for the TGSS sample it is the result of an automated process presented here. After taking into account systematic effects, marginal evidence of a local alignment on scales smaller than $2.5\deg$ is found in the FIRST sample. The probability of this happening by chance is found to be less than $2$ per cent. Further study suggests that on scales up to $1.5\deg$ the alignment is maximal. For one third of the sources, the Radio Galaxy Zoo volunteers identified an optical counterpart. Assuming a flat $\Lambda$CDM cosmology with $\Omega_m = 0.31, \Omega_\Lambda = 0.69$, we convert the maximum angular scale on which alignment is seen into a physical scale in the range $[19, 38]$ Mpc $h_{70}^{-1}$. This result supports recent evidence reported by Taylor and Jagannathan of radio jet alignment in the $1.4$ deg$^2$ ELAIS N1 field observed with the Giant Metrewave Radio Telescope. The TGSS sample is found to be too sparsely populated to manifest a similar signal

Effects of Three Low-Doses of D-Tagatose on Glycemic Control Over Six Months in Subjects with Mild Type 2 Diabetes Mellitus Under Control with Diet and Exercise

The primary objective of this study was to evaluate the safety and the effect of D-tagatose on the glycemic control of subjects with type 2 diabetes as determined by HbA1c levels at the end of 6 months of therapy using the subject\u27s own baseline HbA1c level as a comparator. The determination of the minimal dose required to cause a statistically significant reduction in HbA1c was of particular interest. Eight weeks after screening, the qualifying subjects were randomized to receive one of three doses of D-tagatose: 2.5 g TID, 5.0 g TID or 7.5 g TID. Blood levels of HbA1c, fasting blood glucose concentrations, plasma lipids, changes in body weight, changes in body mass index, and change in insulin levels were checked at each study visit and at the end of the study. Treatment success, as measured by the reduction of HbA1c, was greatest for the 7.5 g D-tagatose dose group, although the difference between the treatments was not statistically significant. For fasting glucose, only the 7.5 g dosage group exhibited reductions from baseline at the 3- and 6-month time points. Mean body weights reduced in a dose-response fashion, with the 5.0 g and the 7.5 g D-tagatose doses providing the greatest reductions. D-tagatose at dosages of 2.5 g, 5.0 g, and 7.5 g TID for six months were well tolerated by this subject population. D-tagatose at 5.0 g TID was the minimal dose required to reduce HbA1c. D-tagatose at 7.5 g TID provided the greatest effect in most measured efficacy parameters

The (Im)possibility of the Intellectual Worker Inside the Neoliberal University

The provocation and point of this paper is that universities of the North during the era of neoliberalism of have been sucked of their human life-giving capacities. What remains are closed doors and bare walls. Lest we give the impression of a hopelessly romantic view of the university (and embark upon a lament for some paradise lost), let us be clear from the outset: there is no such place – and there never has been. As will be outlined below, a consideration of the history of the university reveals it was born and has persistently drawn its life breath from oxygen formed in the tension ridden mix of an impulse to human freedom and accommodation to powers of church, state and capital. But, we contend, history is now the witness to the almost complete dissolution of that tension: to the exhaustion of emancipatory impulses in the service of indoctrination, regulation and accumulation. In the church-state-capital triad, it is the latter that has emerged hegemonic. Importantly, we argue, its dominance has emerged with the rise of what Paul Baran and Paul Sweezy describe as monopoly capital: the move from competitive (small entrepreneurial business) forms to monopolistic (large corporate business) regimes of accumulation (Baran & Sweezy 1966). A central feature of monopoly capitalism is its need for significant financial support of national states and the harnessing of public resources such as universities to feed accumulation. It is no surprise that neoliberalism, despite its neoclassical economic pronouncements, is a ‘big state’ advocate (Harvey 2005). Our argument is that neoliberalism, as the political workhorse of monopoly capitalism, has overseen a makeover of universities so they might behave like a monopoly capitalist corporation. Our time is the time of the near global domination of capital. The university has succumbed. In its colonisation – its capitalisation – the university has not only reinvented itself as a willing ally of capital but has also set about remaking itself in its image

Thermal tides in the Martian middle atmosphere as seen by the Mars Climate Sounder

The first systematic observations of the middle atmosphere of Mars (35–80km) with the Mars Climate Sounder (MCS) show dramatic patterns of diurnal thermal variation, evident in retrievals of temperature and water ice opacity. At the time of writing, the data set of MCS limb retrievals is sufficient for spectral analysis within a limited range of latitudes and seasons. This analysis shows that these thermal variations are almost exclusively associated with a diurnal thermal tide. Using a Martian general circulation model to extend our analysis, we show that the diurnal thermal tide dominates these patterns for all latitudes and all seasons

Probing the physics of narrow-line regions of Seyfert galaxies I: The case of NGC 5427

We have used the Wide Field Spectrograph (WiFeS) on the ANU 2.3m telescope at Siding Spring to observe the nearby, nearly face-on, Seyfert 2 galaxy, NGC 5427. We have obtained integral field spectroscopy of both the nuclear regions and the HII regions in the spiral arms. We have constrained the chemical abundance in the interstellar medium of the extended narrow line region (ENLR) by measuring the abundance gradient in the circum-nuclear \ion{H}{ii} regions to determine the nuclear chemical abundances, and to use these to in turn determine the EUV spectral energy distribution for comparison with theoretical models. We find a very high nuclear abundance, $\sim 3.0$ times solar, with clear evidence of a nuclear enhancement of N and He, possibly caused by massive star formation in the extended ($\sim 100$pc) central disk structure. The circum-nuclear narrow-line region spectrum is fit by a radiation pressure dominated photoionisation model model with an input EUV spectrum from a Black Hole with mass $5\times10^7 M_{\odot}$ radiating at $\sim 0.1$ of its Eddington luminosity. The bolometric luminosity is closely constrained to be $\log L_{\mathrm bol.} = 44.3\pm 0.1$ erg s$^{-1}$. The EUV spectrum characterised by a soft accretion disk and a harder component extending to above 15keV. The ENLR region is extended in the NW-SE direction. The line ratio variation in circum-nuclear spaxels can be understood as the result of mixing \ion{H}{ii} regions with an ENLR having a radius-invariant spectrum.Comment: Accepted for publication in Astronomy and Astrophysics, 14 pages, 13 figure