Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942

Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ~42 IsiA : Photosystem I in Synechococcus PCC 7942 and ~12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes

A macronutrient bulletin for the prairies

Non-Peer ReviewedThis paper briefly highlights some of the contents of a recently completed bulletin, which provides an up-to-date record of the status of our knowledge with regards to crop responses to, and impact on the environment of N, P, K and s, on the Canadian prairies. This 12 Chapter, 527 page book presents information on nutrient balances, trends in fertility levels of soils, nitrogen use efficiency, N, P, K and S cycles, fertilizer N practices, the influence of nutrients on soil organic matter, response of. forages to nutrients, biotechnology and crop nutrition, and the impact of nutrients on the environment. This manuscript, which was prepared through funding provided under the Canada-Saskatchewan Environmental Sustainability Initiative (ESI), should be of considerable assistance to students, educators, scientists and agricultural extensionists in the three prairie provinces

A 25-year review of fertilizer consumption and plant nutrient removal in the prairie provinces

Non-Peer ReviewedNutrient removal I replacement ratios were calculated in Manitoba, Saskatchewan, and Alberta from 1965 to 1989 by dividing total fertilizer (N, P, and K) sales by the total crop removal of plant nutrients. The nutrient removal I replacement ratios revealed that significant depletions of soil reserves of N, P, and K have taken place over the past 25 years. The average negative balance of N, P2O5, and K2O on the prairies is estimated at 640, 125, and 490 thousand tonnes. Even with the substantial increase in the use of fertilizers in the past five years compared to the 25 year average, the nutrient deficit continues to be unacceptably high for nitrogen (485,000 tonnes), only modest for phosphorus (86,000 tonnes), and as could be expected for potassium, has increased significantly to 570,000 tonnes. Overall, the calculations suggest that Manitoba is very close to nitrogen and phosphorus balance. Alberta has a relatively close balance, while Saskatchewan has not only experienced an unacceptably high N and P deficit for the past 25 years, but continues to do so at the present time

Subtraction terms for one-loop amplitudes with one unresolved parton

Fully differential next-to-next-to-leading order calculations require a method to cancel infrared singularities. In a previous publication, I discussed the general setup for the subtraction method at NNLO. In this paper I give all subtraction terms for electron-positron annihilation associated with one-loop amplitudes with one unresolved parton. These subtraction terms are integrated within dimensional regularization over the unresolved one-particle phase space. The results can be used with all variants of dimensional regularization (conventional dimensional regularization, the 't Hooft-Veltman scheme and the four-dimensional scheme).Comment: 27 page

The Stellar-Disk Electric (Short) Circuit: Observational Predictions for a YSO Jet Flow

We discuss the star-disk electric circuit for a young stellar object (YSO) and calculate the expected torques on the star and the disk. We obtain the same disk magnetic field and star-disk torques as given by standard magnetohydrodynamic (MHD) analysis. We show how a short circuit in the star-disk electric circuit may produce a magnetically-driven jet flow from the inner edge of a disk surrounding a young star. An unsteady bipolar jet flow is produced that flows perpendicular to the disk plane. Jet speeds of order hundreds of kilometres per second are possible, while the outflow mass loss rate is proportional to the mass accretion rate and is a function of the disk inner radius relative to the disk co-rotation radius.Comment: 6 pages, 8 figures, Accepted for publication in Astrophysics & Space Scienc

Generative technologies for model animation in the TopCased platform

International audienceDomain Specific Modeling Languages (DSML) are more and more used to handle high level concepts, and thus bring complex software development under control. The increasingly recurring definition of new languages raises the problem of the definition of support tools such as editor, simulator, compiler, etc. In this paper we propose generative technologies that have been designed to ease the development of model animation tools inside the TopCased platform. These tools rely on the automatically generated graphical editors of TopCased and provide additional generators for building model animator graphical interface. We also rely on an architecture for executable metamodel (i.e., the TopCased model execution metamodeling pattern) to bind the behavioral semantics of the modeling language. These tools were designed in a pragmatic manner by abstracting the various model animators that had been hand-coded in the TopCased project, and then validated by refactoring these animators

Understanding the scabbling of concrete using microwave energy

This paper reports on the use of microwave energy to scabble concrete. While the technique is not new, little information exists relating to the controllability of the process, the effect of different types of concrete and the performance and durability of the scabbled concrete post treatment. Concrete blocks supplied by the UK Sellafield nuclear site were treated with microwave energy using a 15kW system, operating at 2.45GHz. The effect of aggregate type (Whinstone, Gravel and Limestone); standoff distance; and effect of surface coating were studied to determine their influence on the systems performance, in terms of mass and area removal rates. Complimentary modelling studies were undertaken relating the power density of the microwave energy to observed scabbling profile. Mass and area removal rates averaged 11.3gs-1 and 3cms-1 respectively on treating large areas to a depth of 25mm. The process was shown to not adversely affect structural properties of the specimens after treatment

Subtraction Terms for Hadronic Production Processes at Next-to-Next-to-Leading Order

I describe a subtraction scheme for the next-to-next-to-leading order calculation of single inclusive production at hadron colliders. Such processes include Drell-Yan, W^{+/-}, Z and Higgs Boson production. The key to such a calculation is a treatment of initial state radiation which preserves the production characteristics, such as the rapidity distribution, of the process involved. The method builds upon the Dipole Formalism and, with proper modifications, could be applied to deep inelastic scattering and e^+ e^- annihilation to hadrons.Comment: 4 page