Unitary control in quantum ensembles: maximizing signal intensity in coherent spectroscopy

Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.     

Resistance to root-lesion nematode Pratylenchus neglectus identified in a new collection of two wild chickpea species (Cicer reticulatum and C. echinospermum) from Turkey

Chickpea (Cicer arietinum) is a major legume crop, with Australia being the second largest producer worldwide. Pratylenchus neglectus is a root-lesion nematode that invades, feeds and reproduces in roots of pulse and cereal crops. In Australia, chickpea and wheat (Triticum aestivum) are commonly grown in rotation and annual damage by P. neglectus accounts for large economic losses to both crops. Cultivated chickpea has narrow genetic diversity that limits the potential for improvement in resistance breeding. New collections of wild chickpea species, C. reticulatum and C. echinospermum, have substantially increased the previously limited world collection of wild Cicer germplasm and offer potential to widen the genetic diversity of cultivated chickpea through the identification of accessions with good resistance. This research assessed 243 C. reticulatum and 86 C. echinospermum accessions for response to P. neglectus in replicated experiments under controlled glasshouse conditions from 2013 and 2014 collection missions that were received, tested and analysed in two experimental sets. Multi-experiment analyses showed lower P. neglectus population densities in both sets of wild Cicer accessions tested than Australia's elite breeding cultivar PBA HatTrick at the significance level p < 0.05. Provisional resistance ratings were given to all genotypes tested in both experimental sets, with C. reticulatum accessions CudiB_008B and Kayat_066 rated as resistant in both Set 1 and Set 2. New sources of resistance to P. neglectus observed in this study can be introgressed into commercial chickpea cultivars to improve their resistance to this nematode.     

Application of char products improves urban soil quality

Urban soils are a key component of the urban ecosystem but little research has considered their quality and management. The use of char or partially combusted char products as a soil amendment is becoming popular worldwide because of perceived benefits to fertility and the potential for increasing carbon sequestration. In this study, we assessed the effect of applying coarse and fine char material on the quality of four different types of soil‐based root‐zone mixes typically used for turfgrass and general landscaping in Singapore: clay loam soil, approved soil mix (ASM, 3 soil:2 compost:1 sand), 50:50 (sand/soil) and 75:25 (sand/soil). Char briquettes made from sawdust were mixed thoroughly at rates of 25, 50 and 75% by volume with the soil mixes. Results showed that addition of char (both coarse and fine) significantly enhanced the carbon content of the mixes, with the largest increase being associated with the 50% and 75% additions. Soil nutrients (total N, extractable P, K, Ca and Mg) and mean weight diameter of aggregates were also significantly increased following the application of char. The clay loam and the 50:50 and 75:25 soil mixes were more responsive to the addition of char than was ASM.     

An Exploratory Investigation of Polar Organic Compounds in Waters from a Lead�CZinc Mine and Mill Complex

Surface water samples were collected in 2006 from a lead mine?Cmill complex in Missouri to investigate possible organic compounds coming from the milling process. Water samples contained relatively high concentrations of dissolved organic carbon (DOC; greater than 20 mg/l) for surface waters but were colorless, implying a lack of naturally occurring aquatic humic or fulvic acids. Samples were extracted by three different types of solid-phase extraction and analyzed by electrospray ionization/mass spectrometry. Because large amounts of xanthate complexation reagents are used in the milling process, techniques were developed to extract and analyze for sodium isopropyl xanthate and sodium ethyl xanthate. Although these xanthate reagents were not found, trace amounts of the degradates, isopropyl xanthyl thiosulfonate and isopropyl xanthyl sulfonate, were found in most locations sampled, including the tailings pond downstream. Dioctyl sulfosuccinate, a surfactant and process filtering aid, was found at concentrations estimated at 350 ??g/l at one mill outlet, but not downstream. Release of these organic compounds downstream from lead?Czinc mine and milling areas has not previously been reported. A majority of the DOC remains unidentified.     

Population dynamical consequences of climate change for a small temperate songbird

Predicting the effects of an expected climatic change requires estimates and modeling of stochastic factors as well as density-dependent effects in the population dynamics. In a population of a small songbird, the dipper (Cinclus cinclus), environmental stochasticity and density dependence both influenced the population growth rate. About half of the environmental variance was explained by variation in mean winter temperature. Including these results in a stochastic model shows that an expected change in climate will strongly affect the dynamics of the population, leading to a nonlinear increase in the carrying capacity and in the expected mean population size.     

Survival of root-lesion nematode <Emphasis Type="Italic">Pratylenchus neglectus</Emphasis> during progressive soil desiccation after growth of wheat in a vertisol

Whether soil desiccation causes a fall in peak population abundances of Pratylenchus neglectus after wheat growth was investigated by drying a vertisol through a range of moisture contents (MC) by both fast and slow drying methods. Live nematodes were then extracted for 2 and 7 days and counted in four life stages (adult and juvenile stages J2, J3 and J4). The population of P. neglectus declined more steeply with decreasing soil moisture content from fast drying than from slow drying. These trends were modelled by regression equations. Upon desiccation of the soil from an initial 64.4% MC to the plant permanent wilting point (31.5% MC), 48% of the nematodes survived after fast drying, but 86% survived after slow drying. With further desiccation to 21% MC only 23% of the P. neglectus population survived after fast drying, whereas 81% of the population survived after slow drying. On continued drying, the fast dried soil was at 11.9% MC after 7 days with virtually no surviving P. neglectus, whereas the slowly dried soil reached 16.5% MC after 8 days with 79% surviving. The P. neglectus population declined by 2.2 and 0.5% per 1% loss of soil moisture for fast and slow drying, respectively. With fast drying, all life stages declined; however, with slow drying, only the J2 stage declined with 44% surviving at 16.5% MC. This information can be applied to crop growth modelling, to extraction techniques for soil from the glasshouse and field, and to consideration of whether molecular methods measure DNA from recently dead nematodes killed by soil desiccation in the field giving an overestimation of the number of live nematodes.     

Verification of traffic-induced soil compaction after long-term ploughing and 10 years minimum tillage on clay loam soil in South-East Norway

Grain yields are presented from a 10-year field trial with four tillage regimes (annual ploughing, harrowing only, ploughing/harrowing alternate years and minimum tillage) on clay loam. We also present soil physical analyses and use the compaction verification tool (CVT) to assess compaction on plots with annual ploughing and minimum tillage, after using slurry tankers with contrasting wheel loads (4.1 Mg, 6.6 Mg) and wheeling intensities (1×/10×) in the 11th trial year, and yields monitored two years after compaction. Winter wheat yields in the period before compaction were strongly affected by tillage, with annual ploughing giving on average 24% higher yield than direct drilling. Both wheat and oats were far less affected in treatments with harrowing only or ploughing/harrowing alternate years, on average within 6% of annual ploughing. Yields after compaction were affected by both previous tillage and compaction intensity. In the first year, single wheeling after annual ploughing gave 23% yield reduction with 4.1 Mg wheel load and 28% reduction with 6.6 Mg wheel load, whilst multiple wheeling gave 14% reduction at 6.6 Mg wheel load. Yield reductions after minimum tillage ranged from 63% (single wheeling with 4.1 Mg) to 100% (multiple wheeling with 6.6 Mg). Similar trends were found in the second year. The soil physical data indicated that all wheeling led to changes in bulk density, pore sizes and permeability in both topsoil and subsoil on both sampled tillage plots. However, effects in the subsoil were partly masked by the soil's high initial bulk density, partly due to its high clay content. The CVT, which plots air capacity against hydraulic conductivity, suggested some harmful compaction on both plots, with the minimum tillage plot being less affected than the ploughed plot. However, yield results did not support this conclusion, indicating that other factors limited yields on the minimum tilled plot.