An energy-momentum consistent time integration scheme based on a mixed framework for non-linear electro-elastodynamics

The objective of the present work is the introduction of new mixed variational principles for EM time integrators in electromechanics, hence bridging the gap between the previous work presented by the authors in References [11] and [1], opening up the possibility to a variety of new Finite Element implementations

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Climate change and potato production in contrasting South African agro-ecosystems 2 : Assessing risks and opportunities of adaptation strategies

This study aims to assess the risks and opportunities posed by climate change to potato growers in South Africa and to evaluate adaptation measures in the form of changes in planting time growers could adopt to optimise land and water use efficiencies in potato, using a climate model of past, present-day and future climate over southern Africa and the LINTUL crop growth model. This was done for distinct agro-ecosystems in South Africa: the southern Mediterranean area where potato still is grown year round with a doubling of the number of hot days between 1960 and 2050, the Eastern Free State with summer crops only and Limpopo with currently autumn, winter and spring crops where the number of hot days increases sevenfold and in future the crop will mainly be grown in winter. A benefit here will be a drastic reduction of frost days from 0.9 days per winter to 0. Potato crops in the agroecosystems will benefit considerably from increased CO2 levels such as increased tuber yield and reduced water use by the crop, if planting is shifted to appropriate times of the year. When the crop is grown in hot periods, however, these benefits are counteracted by an increased incidence of heat stress and increased evapotranspiration, leading in some instances to considerably lower yields and water use efficiencies. Therefore year-round total production at the Sandveld stabilizes at around 140 Mgha−1 (yield reduction in summer and yield increase in winter), increases by about 30% in the Free State and stays at about 95 tha−1 at Limpopo where yieldPotatoes South Africa and the Netherlands Ministry of Economy, Agriculture and Innovation Agriculturehttp://link.springer.com/journal/11540hb201

Targeted enrichment of genomic DNA regions for next-generation sequencing

In this review, we discuss the latest targeted enrichment methods and aspects of their utilization along with second-generation sequencing for complex genome analysis. In doing so, we provide an overview of issues involved in detecting genetic variation, for which targeted enrichment has become a powerful tool. We explain how targeted enrichment for next-generation sequencing has made great progress in terms of methodology, ease of use and applicability, but emphasize the remaining challenges such as the lack of even coverage across targeted regions. Costs are also considered versus the alternative of whole-genome sequencing which is becoming ever more affordable. We conclude that targeted enrichment is likely to be the most economical option for many years to come in a range of settings

A new energy–momentum time integration scheme for non-linear thermo-mechanics

The aim of this paper is the design a new one-step implicit and thermodynamically consistent Energy–Momentum (EM)preserving time integration scheme for the simulation of thermo-elastic processes undergoing large deformations and temperature fields. Following Bonet et al. (2020), we consider well-posed constitutive models for the entire range of deformations and temperature. In that regard, the consideration of polyconvexity inspired constitutive models and a new tensor cross product algebra are shown to be crucial in order to derive the so-called discrete derivatives, fundamental for the construction of the algorithmic derived variables, namely the second Piola–Kirchoff stress tensor and the entropy (or the absolute temperature).The proposed scheme inherits the advantages of the EM scheme recently published by Franke et al. (2018), whilst resulting in a simpler scheme from the implementation standpoint. A series of numerical examples will be presented in order to demonstrate the robustness and applicability of the new EM scheme. Although the examples presented will make use of a temperature-based version of the EM scheme (using the Helmholtz free energy as the thermodynamical potential and the temperature as thethermodynamical state variable), we also include in an Appendix an entropy-based analogue EM scheme (using the internal energy as the thermodynamical potential and the entropy as the thermodynamical state variable)

b-physics signals of the lightest CP-odd Higgs in the NMSSM at large tan beta

We investigate the low energy phenomenology of the lighter pseudoscalar $A_1^0$ in the NMSSM. The $A_1^0$ mass can naturally be small due to a global $U(1)_R$ symmetry of the Higgs potential, which is only broken by trilinear soft terms. The $A_1^0$ mass is further protected from renormalization group effects in the large $\tan \beta$ limit. We calculate the $b \to s A_1^0$ amplitude at leading order in $\tan \beta$ and work out the contributions to rare $K$, $B$ and radiative $\Upsilon$-decays and $B -\bar B$ mixing. We obtain constraints on the $A_1^0$ mass and couplings and show that masses down to ${\cal{O}}(10)$ MeV are allowed. The $b$-physics phenomenology of the NMSSM differs from the MSSM in the appearance of sizeable renormalization effects from neutral Higgses to the photon and gluon dipole operators and the breakdown of the MSSM correlation between the $B_s \to \mu^+ \mu^-$ branching ratio and $B_s - \bar B_s$ mixing. For $A_1^0$ masses above the tau threshold the $A_1^0$ can be searched for in $b \to s \tau^+ \tau^-$ processes with branching ratios \lsim 10^{-3}.Comment: 18 pages, 3 figures; references adde

Climate change and potato production in contrasting South African agro-ecosystems 1. Effects on land and water use efficiencies

Explorations of the impact of climate change on potential potato yields were obtained by downscaling the projections of six different coupled climate models to high spatial resolution over southern Africa. The simulations of daily maximum and minimum temperatures, precipitation, wind speed, and solar radiation were used as input to run the crop growth model LINTUL-Potato. Pixels representative for potato growing areas were selected for four globally occurring agro-ecosystems: rainy and dry winter and summer crops. The simulated inter-annual variability is much greater for rainfall than for temperature. Reference evapotranspiration and radiation are projected to hardly decline over the 90-year period, whilst temperatures are projected to rise significantly by about 1.9 °C. From literature, it was found that radiation use efficiency of potato increased with elevated CO2 concentrations by almost 0.002 gMJ−1ppm−1. This ratio was used to calculate the CO2 effect on yields between 1960 and 2050, when CO2 concentration increases from 315 to 550 ppm.Within this range, evapotranspiration by the potato crop was reduced by about 13% according to literature. Simulated yield increase was strongest in the Mediterraneantype winter crop (+37%) and least under Mediterranean summer (+12%) and relatively warm winter conditions (+14%) closer to the equator. Water use efficiency also increased most in the cool rainy Mediterranean winter (+45%) and least so in the winter crop closer to the equator (+14%). It is concluded from the simulations that for all four agro-ecosystems possible negative effects of rising temperatures and reduced availability of water for potato are more than compensated for by the positive effect of increased CO2 levels on water use efficiency and crop productivity.Potatoes South Africa and The Netherlands Ministry of Economic Affairshttp://link.springer.com/journal/11540hb201

Climate Change and Potato Production in Contrasting South African Agro-Ecosystems 3. Effects on Relative Development Rates of Selected Pathogens and Pests

A set of daily weather data simulations for 1961 to 2050 were used to calculate past and future trends in pest and disease pressure in potato cropping systems at three agro-ecologically distinct sites in South Africa: the Sandveld, the Eastern Free State and Limpopo. The diseases and pests modelled were late blight, early blight and brown spot, blackleg and soft rot, root-knot nematodes and the peach-potato aphid Myzus persicae (as indicator of Potato virus Y and Potato leaf roll virus). The effects of climate on trends in relative development rates of these pathogens and pests were modelled for each pathogen and pest using a set of quantitative parameters, which included specific temperature and moisture requirements for population growth, compiled from literature. Results showed that the cumulative relative development rate (cRDR) of soft rot and blackleg, root-knot nematodes and M. persicae will increase over the 90-year period in the areas under consideration. The cRDR of early blight and brown spot is likely to increase in the wet winter and wet summer crops of the Sandveld and Eastern Free State, respectively, but remains unchanged in the dry summer and dry winter crops of the Sandveld and Limpopo, respectively. Climate change will decrease the cRDR of late blight in all of the cropping systems modelled, except in the wet winter crop of the Sandveld. These results help to set priorities in research and breeding, specifically in relation to management strategies for diseases and pests

Resource use efficiencies as indicators of ecological sustainability in potato production : a South African case study

Potato, the most important vegetable crop in South Africa, is produced in many distinct geographical regions differing in climate, soils, production seasons and management practices and access to markets. These differences affect the amount of input resources required to produce potatoes as well as yields and crop value, and therefore the use efficiencies of land, water, nutrients, seed and energy. Resource use efficiencies affect the ecological and financial sustainability of potato production in this region, which has in general less favourable potato growing conditions than north-western Europe and the U.S.A., where high resource use efficiencies are usually recorded. This study aimed to assess and benchmark South African potato production regions, representing a wide range of growing conditions, regarding their use of input resources and to identify resource-intensive practices, which may suggest inefficient use of inputs. Surveys were conducted in 2013 and 2014 by interviewing growers in all production regions, to provide data on resource use efficiencies. Quantitative modelling approaches were applied to calculate carbon footprints as a proxy of energy use efficiency, potential crop yields and irrigation needs for each region. Variability in the gap between potential and actual yield was used to identify yield limiting factors. Actual yields achieved were on average 60% of the potential yield, suggesting fairly efficient use of available production factors. Water, seed and nutrient use efficiencies differed widely between and within regions and were not directly proportional to water requirements and yields achieved. Fertilizers (34%) and irrigation (30%) were the greatest contributors to energy use in potato crop production. Energy required to pump water was strongly related to the amount of irrigation applied, pumping depth and distance. Long distance travel of produce to retail points contributed substantially to energy use. Significant improvements in efficiencies are possible by improving management practices. Analysis of the variability in resource use efficiencies between farms and regions provided production sustainability indicators that can assist growers in identifying inefficient practices and yield limiting factors. These can be addressed through the use of decision support systems, such as irrigation scheduling tools, to improve resource use efficiencies and the sustainability of production, not only for the production efficiency of the specific study area, but also for the economic efficiency of potato production anywhere else.This work was financially supported by Potatoes South Africa.http://www.elsevier.com/locate/fcr2017-12-31hb2016Plant Production and Soil Scienc