Rocket having barium release system to create ion clouds in the upper atmosphere

A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented

Impacts of Climate Change on Livestock Systems: What We Know and What We Don’t Know

Climate changes and the associated increases in atmospheric carbon dioxide concentration are just two of many possible future drivers of change in grassland systems and whilst there are significant uncertainties around these, they are probably more effectively characterised than many other drivers. The challenge for grasslands systems research is not so much trying to precisely predict future climate in the face of unresolvable uncertainty but rather to work with decision-makers to enhance their decisions for a range of possible climates, build their capacity to make sound risk-based and informed decisions and increase the array of options available for adaptation. There are many adaptations possible to address key climate impacts such as increased heat stress, altered pests and disease risk, vegetation change, increased risk of soil degradation and changes in forage quantity, quality and the variability of these. Many of these adaptations are extensions of existing best management practice. However, it is important to explore adaptations that are beyond incremental change to existing systems to be inclusive of more substantial systems change and even transformational changes. There is a need also to consider adaptations beyond the farm scale including in relation to value chains, institutional change and policy development. It is these areas in particular where there are likely to be increasing demands for research

Noncovariant gauge fixing in the quantum Dirac field theory of atoms and molecules

Starting from the Weyl gauge formulation of quantum electrodynamics (QED), the formalism of quantum-mechanical gauge fixing is extended using techniques from nonrelativistic QED. This involves expressing the redundant gauge degrees of freedom through an arbitrary functional of the gauge-invariant transverse degrees of freedom. Particular choices of functional can be made to yield the Coulomb gauge and Poincar\'{e} gauge representations. The Hamiltonian we derive therefore serves as a good starting point for the description of atoms and molecules by means of a relativistic Dirac field. We discuss important implications for the ontology of noncovariant canonical QED due to the gauge freedom that remains present in our formulation.Comment: 8 pages, 0 figure

Glacial geomorphology of the Great Glen Region of Scotland

This paper presents a detailed glacial Main Map of the Great Glen region of Scotland, UK, covering an area of over 6800 km2 extending from 56°34′7″ to 57°41′1″ N and from 3°44′2″ to 5°33′24″ W. This represents the first extensive mapping of the glacial geomorphology of the Great Glen and builds upon previous studies that conducted localised field mapping or ice-sheet wide mapping using remote sensing. Particular emphasis is placed on deriving medium-scale glacial retreat patterns from these data, and examining differences in landsystem assemblages across the region. Features were typically mapped at a scale of 1:8000 to 1:10,000 and will be used to investigate the pattern and dynamics of the British-Irish Ice Sheet during deglaciation. Mapping was conducted using the NEXTMap digital terrain model. In total, 17,637 glacial landforms were mapped, with 58% identified as moraines, 23% as meltwater channels, 10% as bedrock controlled glacial lineations, 3% as eskers, 2% as cirques or arêtes, 2% as kame topography or kame terraces, and 1% as drumlins. Additionally, 10 palaeo-lake shorelines were identified. Complex landform assemblages in the form of streamlined subglacial bedforms, moraines and glaciofluvial features exist across the region. Extensive subglacial meltwater networks are found over the Monadhliath Mountain Range. Transverse and longitudinal moraine ridges generally arc across valley floors or are located on valley slopes respectively. Hummocky moraines are found almost exclusively across Rannoch Moor. Finally, eskers, meltwater channels and kame landforms form spatial relationships along the axis of Strathspey. These glacial landsystems reveal the dynamics and patterns of retreat of the British-Irish Ice Sheet during the last deglaciation

Non-ribosomal phylogenetic exploration of Mollicute species:New insights into haemoplasma taxonomy

AbstractNine species of uncultivable haemoplasmas and several Mycoplasma species were examined by partial sequencing of two protein-encoding housekeeping genes. Partial glyceraldehyde-3-phosphate dehydrogenase (gapA) and heat shock protein 70 (dnaK) gene sequences were determined for these Mollicute species; in total nine gapA sequences and ten dnaK sequences were obtained. Phylogenetic analyses of these sequences, along with those of a broad selection of Mollicute species downloaded from GenBank, for the individual genes, and for the gapA and dnaK concatenated data set, revealed a clear separation of the haemoplasmas from other species within the Mycoplasma genus; indeed the haemoplasmas resided within a single clade which was phylogenetically detached from the pneumoniae group of Mycoplasmas. This is the first report to examine the use of gapA and dnaK, as well as a concatenated data set, for phylogenetic analysis of the haemoplasmas and other Mollicute species. These results demonstrate a distinct phylogenetic separation between the haemoplasmas and Mycoplasmas that corresponds with the biological differences observed in these species, indicating that further evaluation of the haemoplasmas’ relationship with the Mycoplasma genus is required to determine whether reclassification of the haemoplasmas is necessary

Seasonal patterns of fine root production and turnover in a mature rubber tree (Hevea brasiliensis Müll. Arg.) stand- differentiation with soil depth and implications for soil carbon stocks

Fine root dynamics is a main driver of soil carbon stocks, particularly in tropical forests, yet major uncertainties still surround estimates of fine root production and turnover. This lack of knowledge is largely due to the fact that studying root dynamics in situ, particularly deep in the soil, remains highly challenging. We explored the interactions between fine root dynamics, soil depth, and rainfall in mature rubber trees (Hevea brasiliensis Müll. Arg.) exposed to sub-optimal edaphic and climatic conditions. A root observation access well was installed in northern Thailand to monitor root dynamics along a 4.5 m deep soil profile. Image-based measurements of root elongation and lifespan of individual roots were carried out at monthly intervals over 3 years. Soil depth was found to have a significant effect on root turnover. Surprisingly, root turnover increased with soil depth and root half-life was 16, 6–8, and only 4 months at 0.5, 1.0, 2.5, and 3.0 m deep, respectively (with the exception of roots at 4.5 m which had a half-life similar to that found between depths of 1.0 and 2.5 m). Within the first two meters of the soil profile, the highest rates of root emergence occurred about 3 months after the onset of the rainy season, while deeper in the soil, root emergence was not linked to the rainfall pattern. Root emergence was limited during leaf flushing (between March and May), particularly within the first two meters of the profile. Between soil depths of 0.5 and 2.0 m, root mortality appeared independent of variations in root emergence, but below 2.0 m, peaks in root emergence and death were synchronized. Shallow parts of the root system were more responsive to rainfall than their deeper counterparts. Increased root emergence in deep soil toward the onset of the dry season could correspond to a drought acclimation mechanism, with the relative importance of deep water capture increasing once rainfall ceased. The considerable soil depth regularly explored by fine roots, even though significantly less than in surface layers in terms of root length density and biomass, will impact strongly the evaluation of soil carbon stocks

Advanced deep space communication systems study Final report

Deep space communication system requirements for period 1970 to 198

A phenomenological approach to normal form modeling: a case study in laser induced nematodynamics

An experimental setting for the polarimetric study of optically induced dynamical behavior in nematic liquid crystal films has allowed to identify most notably some behavior which was recognized as gluing bifurcations leading to chaos. This analysis of the data used a comparison with a model for the transition to chaos via gluing bifurcations in optically excited nematic liquid crystals previously proposed by G. Demeter and L. Kramer. The model of these last authors, proposed about twenty years before, does not have the central symmetry which one would expect for minimal dimensional models for chaos in nematics in view of the time series. What we show here is that the simplest truncated normal forms for gluing, with the appropriate symmetry and minimal dimension, do exhibit time signals that are embarrassingly similar to the ones found using the above mentioned experimental settings. The gluing bifurcation scenario itself is only visible in limited parameter ranges and substantial aspect of the chaos that can be observed is due to other factors. First, out of the immediate neighborhood of the homoclinic curve, nonlinearity can produce expansion leading to chaos when combined with the recurrence induced by the homoclinic behavior. Also, pairs of symmetric homoclinic orbits create extreme sensitivity to noise, so that when the noiseless approach contains a rich behavior, minute noise can transform the complex damping into sustained chaos. Leonid Shil'nikov taught us that combining global considerations and local spectral analysis near critical points is crucial to understand the phenomenology associated to homoclinic bifurcations. Here this helps us construct a phenomenological approach to modeling experiments in nonlinear dissipative contexts.Comment: 25 pages, 9 figure

Tight-binding study of high-pressure phase transitions in titanium: alpha to omega and beyond

We use a tight-binding total energy method, with parameters determined from a fit to first-principles calculations, to examine the newly discovered gamma phase of titanium. Our parameters were adjusted to accurately describe the alpha Ti-omega Ti phase transition, which is misplaced by density functional calculations. We find a transition from omega Ti to gamma Ti at 102 GPa, in good agreement with the experimental value of 116 GPa. Our results suggest that current density functional calculations will not reproduce the omega Ti-gamma Ti phase transition, but will instead predict a transition from omega Ti to the bcc beta Ti phase.Comment: 3 encapsulated Postscript figures, submitted to Phyical Review Letter