The Effect of Nitrogen Rates and Plant Density on Grain Yield Components and Persistence in Intermediate Wheatgrass (\u3ci\u3eThinopyrum intermedium\u3c/i\u3e) and Mountain Rye (\u3ci\u3eSecale strictum\u3c/i\u3e)

Intermediate wheatgrass (IWG; Thinopyrum intermedium) and Mountain Rye (Mtn Rye; Secale strictum) have potential for release as dual-purpose (grazing and grain production) perennial grains in Australia due to their superior longevity compared to hybrid perennial wheats. Initially developed as perennial forage grasses, few management guidelines exist to inform agronomic practices to maximise grain yields and profitability in Australian environments. An experiment was established in 2020 to examine the effect of plant density and nitrogen rates on grain yield components. The experiment compared the two species (IWG, Mtn Rye) sown at three plant densities (50, 100 and 200 plants/m2) with three nitrogen rates (0, 100, 200 kg/ha N). Overall, in the first year of production, Mtn Rye had higher grain yields than Kernza although yield decreased with increasing N rates. With further selection for floret fertility and seed size, Mtn Rye could prove a successful candidate for a perennial grain crop in Australia

Casimir force between sharp-shaped conductors

Casimir forces between conductors at the sub-micron scale cannot be ignored in the design and operation of micro-electromechanical (MEM) devices. However, these forces depend non-trivially on geometry, and existing formulae and approximations cannot deal with realistic micro-machinery components with sharp edges and tips. Here, we employ a novel approach to electromagnetic scattering, appropriate to perfect conductors with sharp edges and tips, specifically to wedges and cones. The interaction of these objects with a metal plate (and among themselves) is then computed systematically by a multiple-scattering series. For the wedge, we obtain analytical expressions for the interaction with a plate, as functions of opening angle and tilt, which should provide a particularly useful tool for the design of MEMs. Our result for the Casimir interactions between conducting cones and plates applies directly to the force on the tip of a scanning tunneling probe; the unexpectedly large temperature dependence of the force in these configurations should attract immediate experimental interest

Stable suspension and dispersion-induced transitions from repulsive Casimir forces between fluid-separated eccentric cylinders

Using an exact numerical method for finite nonplanar objects, we demonstrate a stable mechanical suspension of a silica cylinder within a metallic cylinder separated by ethanol, via a repulsive Casimir force between the silica and the metal. We investigate cylinders with both circular and square cross sections, and show that the latter exhibit a stable orientation as well as a stable position, via a method to compute Casimir torques for finite objects. Furthermore, the stable orientation of the square cylinder is shown to undergo an unusual 45 degrees transition as a function of the separation lengthscale, which is explained as a consequence of material dispersion.Comment: Published in Physical Review Letters. Vol. 101, page, 190404 (2008

Towards improved socio-economic assessments of ocean acidification’s impacts

Ocean acidification is increasingly recognized as a component of global change that could have a wide range of impacts on marine organisms, the ecosystems they live in, and the goods and services they provide humankind. Assessment of these potential socio-economic impacts requires integrated efforts between biologists, chemists, oceanographers, economists and social scientists. But because ocean acidification is a new research area, significant knowledge gaps are preventing economists from estimating its welfare impacts. For instance, economic data on the impact of ocean acidification on significant markets such as fisheries, aquaculture and tourism are very limited (if not non-existent), and non-market valuation studies on this topic are not yet available. Our paper summarizes the current understanding of future OA impacts and sets out what further information is required for economists to assess socio-economic impacts of ocean acidification. Our aim is to provide clear directions for multidisciplinary collaborative research

Entrepreneurial ecosystems, agency and regional development: Emergence and new path creation in the Cardiff city region

This paper addresses the process of entrepreneurial ecosystem emergence in regions and the mechanisms through which new industrial paths are created. It focuses on the context of a relatively weak economic region and develops a mode of analysis that considers the role of human agency within the emergence of entrepreneurial ecosystems. This analysis addresses the case study of the Cardiff city region in the United Kingdom. It indicates that the revitalisation of lagging regions through an entrepreneurial ecosystem approach is likely to be contingent upon a number of important components: (1) access to potential entrepreneurial agency, (2) the engagement of ‘enlightened’ local political agency and (3) the formation of a collective agency across entrepreneurial and political agents as well as other relevant stakeholders. The emergence of collective agency in the city region is found to have led to new policies, networks and entrepreneurial support within the high-tech industry, coupled with the development of new industrial paths and improved economic conditions. The paper argues that adopting an agency-based approach to analysing entrepreneurial emergence highlights the importance of key human actors in such emergence. It is concluded that lagging regions can trigger a process of development through new path creation stemming from the emergence of an entrepreneurial ecosystem

The first massive compact companion in a wide orbit around a hot subdwarf star

We report the discovery of the first hot subdwarf B (sdB) star with a massive compact companion in a wide ($P=892.5\pm60.2\,{\rm d}$) binary system. It was discovered based on an astrometric binary solution provided by the Gaia mission Data Release 3. We performed detailed analyses of the spectral energy distribution (SED) as well as spectroscopic follow-up observations and confirm the nature of the visible component as a sdB star. The companion is invisible despite of its high mass of $M_{\rm comp}=1.50_{-0.45}^{+0.37}\,M_{\rm \odot}$. A main sequence star of this mass would significantly contribute to the SED and can be excluded. The companion must be a compact object, either a massive white dwarf or a neutron star. Stable Roche lobe overflow to the companion likely led to the stripping of a red giant and the formation of the sdB, the hot and exposed helium core of the giant. Based on very preliminary data, we estimate that $\sim9\%$ of the sdBs might be formed through this new channel. This binary might also be the prototype for a new progenitor class of supernovae type Ia, which has been predicted by theory.Comment: 11 pages, accepted for publication in A&

Measurements of the Casimir-Lifshitz force in fluids: the effect of electrostatic forces and Debye screening

In this work, we present detailed measurements of the Casimir-Lifshitz force between two gold surfaces (a sphere and a plate) immersed in ethanol and study the effect of residual electrostatic forces, which are dominated by static fields within the apparatus and can be reduced with proper shielding. Electrostatic forces are further reduced by Debye screening through the addition of salt ions to the liquid. Additionally, the salt leads to a reduction of the Casimir-Lifshitz force by screening the zero-frequency contribution to the force; however, the effect is small between gold surfaces at the measured separations and within experimental error. An improved calibration procedure is described and compared to previous methods. Finally, the experimental results are compared to Lifshitz's theory and found to be consistent for the materials used in the experiment.Comment: 11 figures. PRA in pres