Cultivar considerations and pod sealants for straight-combining canola in Saskatchewan

Non-Peer ReviewedWhile the recommended and preferred harvest practice in western Canada is to swath canola (Brassica napus L.), there is appreciable interest in straight-combining this crop. In a recent study, five cultivars were harvested according to one of four harvest treatments and evaluated for seed yield, yield loss due to shattering, percent green seed and seed size. The cultivars included four B. napus hybrids and an open-pollinated canola quality B. juncea variety. Harvest strategies were swathed, straight-combined without a pod sealant, straight-combined with Pod Ceal DC® and straight-combined with Pod-Stik®. While average yields ranged from 894-3066 kg ha-1, cultivar rankings for yield were generally consistent across sites. Seed yields were equal when averaged across harvest treatments and sites, but swathed yields differed from straight-combined yields 50% of the time for individual sites. At two sites, straight-combining produced 142-370 kg ha-1 higher yields than swathing while, when harvest was delayed due to unfavourable weather, swathed yields were 276-413 kg ha-1 higher. A 217 kg ha-1 yield increase occurred with pod sealants at one site, but there were no differences amongst the two products and pod sealants did not affect yields of straight-combined canola at the remaining seven sites. Pod sealants did not have a measurable effect on shattering losses, even under high shattering conditions. In contrast, cultivar effects on seed loss were generally significant with losses from one of the napus cultivars being particular and consistently low, especially when overall shattering losses were high. On average, losses for all cultivars were 4% of the total yield when harvest was completed reasonably close to the optimal stage. Straight-combining resulted in a small but significant increase in percent green seed and seed size but pod sealants did not affect seed quality in any cases. In conclusion, straight-combining can be a viable alternative to swathing, but substantial yield losses may occur if harvest is delayed too long. Important varietal differences in shattering losses were detected and cultivar selection appears to be a factor of greater importance than pod sealants for growers planning to straight-combine canola

High porosity metallic glass foam: A powder metallurgy route

A powder metallurgy route to the fabrication of metallic glass foam is introduced. The method involves consolidating metallic glass powder blended with blowing agent particulates to produce expandable precursors, capable of yielding foams with porosities as high as 86%. The foams are found to inherit the strength of the parent metallic glass and to be able to deform heavily toward full densification absorbing high amounts of energy

Complexity-based learning and teaching: a case study in higher education

This paper presents a learning and teaching strategy based on complexity science and explores its impacts on a higher education game design course. The strategy aimed at generating conditions fostering individual and collective learning in educational complex adaptive systems, and led the design of the course through an iterative and adaptive process informed by evidence emerging from course dynamics. The data collected indicate that collaboration was initially challenging for students, but collective learning emerged as the course developed, positively affecting individual and team performance. Even though challenged, students felt highly motivated and enjoyed working on course activities. Their perception of progress and expertise were always high, and the academic performance was on average very good. The strategy fostered collaboration and allowed students and tutors to deal with complex situations requiring adaptation

Collisional kinetics of non-uniform electric field, low-pressure, direct-current discharges in H2_{2}

A model of the collisional kinetics of energetic hydrogen atoms, molecules, and ions in pure H$_2$ discharges is used to predict H$_\alpha$ emission profiles and spatial distributions of emission from the cathode regions of low-pressure, weakly-ionized discharges for comparison with a wide variety of experiments. Positive and negative ion energy distributions are also predicted. The model developed for spatially uniform electric fields and current densities less than $10^{-3}$ A/m$^2$ is extended to non-uniform electric fields, current densities of $10^{3}$ A/m$^2$, and electric field to gas density ratios $E/N = 1.3$ MTd at 0.002 to 5 Torr pressure. (1 Td = $10^{-21}$ V m$^2$ and 1 Torr = 133 Pa) The observed far-wing Doppler broadening and spatial distribution of the H$_\alpha$ emission is consistent with reactions among H$^+$, H$_2^+$, H$_3^+$, and H$^-H$ ions, fast H atoms, and fast H$_2$ molecules, and with reflection, excitation, and attachment to fast H atoms at surfaces. The H$_\alpha$ excitation and H$^-$ formation occur principally by collisions of fast H, fast H$_2$, and H$^+$ with H$_2$. Simplifications include using a one-dimensional geometry, a multi-beam transport model, and the average cathode-fall electric field. The H$_\alpha$ emission is linear with current density over eight orders of magnitude. The calculated ion energy distributions agree satisfactorily with experiment for H$_2^+$ and H$_3^+$, but are only in qualitative agreement for H$^+$ and H$^-$. The experiments successfully modeled range from short-gap, parallel-plane glow discharges to beam-like, electrostatic-confinement discharges.Comment: Submitted to Plasmas Sources Science and Technology 8/18/201

Numerical simulation of unconstrained cyclotron resonant maser emission

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of Auroral Kilometric Radiation (AKR) an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiC code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared to waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.Publisher PD

Development of control systems for space shuttle vehicles, volume 1

Control of winged two-stage space shuttle vehicles was investigated. Control requirements were determined and systems capable of meeting these requirements were synthesized. Control requirements unique to shuttles were identified. It is shown that these requirements can be satisfied by conventional control logics. Linear gain schedule controllers predominate. Actuator saturations require nonlinear compensation in some of the control systems

The cytoplasm of living cells: A functional mixture of thousands of components

Inside every living cell is the cytoplasm: a fluid mixture of thousands of different macromolecules, predominantly proteins. This mixture is where most of the biochemistry occurs that enables living cells to function, and it is perhaps the most complex liquid on earth. Here we take an inventory of what is actually in this mixture. Recent genome-sequencing work has given us for the first time at least some information on all of these thousands of components. Having done so we consider two physical phenomena in the cytoplasm: diffusion and possible phase separation. Diffusion is slower in the highly crowded cytoplasm than in dilute solution. Reasonable estimates of this slowdown can be obtained and their consequences explored, for example, monomer-dimer equilibria are established approximately twenty times slower than in a dilute solution. Phase separation in all except exceptional cells appears not to be a problem, despite the high density and so strong protein-protein interactions present. We suggest that this may be partially a byproduct of the evolution of other properties, and partially a result of the huge number of components present.Comment: 11 pages, 1 figure, 1 tabl

On the form of growing strings

Patterns and forms adopted by Nature, such as the shape of living cells, the geometry of shells and the branched structure of plants, are often the result of simple dynamical paradigms. Here we show that a growing self-interacting string attached to a tracking origin, modeled to resemble nascent polypeptides in vivo, develops helical structures which are more pronounced at the growing end. We also show that the dynamic growth ensemble shares several features of an equilibrium ensemble in which the growing end of the polymer is under an effective stretching force. A statistical analysis of native states of proteins shows that the signature of this non-equilibrium phenomenon has been fixed by evolution at the C-terminus, the growing end of a nascent protein. These findings suggest that a generic non-equilibrium growth process might have provided an additional evolutionary advantage for nascent proteins by favoring the preferential selection of helical structures.Comment: 4 pages, 3 figures. Accepted for publication in Phys. Rev. Let

Brahman Genetics Negatively Impact Protein Degradation and Tenderness of Longissimus Lumborum Steaks, but do Not Influence Collagen Cross-Linking

Beef tenderness is an important factor contributing to consumer eating satisfaction of beef products. Tenderness is dependent on several factors including: breed-type, postmortem age time, myofibrillar muscle protein degradation, and collagen content. During the past 30 years, numerous studies have indicated steaks from cattle with a greater percentage of Brahman genetics are tougher than steaks from Bos taurus cattle. The cause of tougher steaks is commonly attributed to Brahman cattle having a greater calpastatin activity which inhibits calpains, the enzymes responsible for myofibrillar protein degradation during the postmortem aging process. Some researchers have reported calpastatin activity was poorly correlated to tenderness of steaks from Brahman cattle. Others have reported sensory panelists indicated steaks from cattle with increasing percentages of Brahman genetics have an increase in the amount of connective tissue or collagen. Additionally, researchers have reported an increase in expression of genes that play a role in cross-linking of collagen which decreases collagen solubility. Due to these findings, we hypothesized steaks from cattle with greater Brahman genetics have more collagen cross-links and therefore a less soluble collagen fraction. The objective of this study was to evaluate the effect of Brahman genetics on protein degradation, collagen cross-linking, and meat tenderness of strip loin steaks