Duncan Joseph Greenwood. 16 October 1932 — 13 February 2010

During his 55-year career as a highly distinguished scientist, Duncan Greenwood made a major contribution to the field of soil science and plant nutrition. His early studies on soil aeration revolutionized thinking on the mechanisms by which oxygen influences the activity of microorganisms and their metabolism of organic substances in structured soil. His ideas resulted in the ‘micro-site concept of soil aeration’, which is still widely accepted today. Later he turned his attention to the nutritional requirements of vegetable crops at a time when the horticultural industry was starting to introduce inorganic fertilizers. He developed a novel static model of N, P and K response, which he used to produce the first scientifically based inorganic fertilizer recommendations for 23 different vegetable crops. Not satisfied with this major development, Duncan started to create more sophisticated dynamic models using novel widely applicable relationships that took more account of the effects of weather on nutrient behaviour in the soil and plant. He not only used these to provide important insights into many of the complex interacting processes involved, but also incorporated them into some of the first computer-based decision support systems for practical site-specific fertilizer advice for the vegetable growing industry. The application of these advances had an important effect on the efficiency of crop production and the reduction of associated environmental impacts. Duncan continued to devise new models for nutrient and water use throughout the rest of his career and to explore ways of applying them in different areas of soil and crop science.

Plant low-K responses are partly due to Ca and the low-K biomarker putrescine does not protect from Ca side effects but acts as a metabolic regulator

Effects of K deficiency have been investigated for several decades and recently, progress has been made in identifying metabolomics signatures thereby offering potential to monitor the K status of crops in the field. However, effects of low K conditions could also be due to the antagonism with other nutrients like calcium (Ca) and the well-known biomarker of K deficiency, putrescine, could be a response to Ca/K imbalance rather than K deficiency. We carried out experiments in sunflower grown at either low or high K, at high or low Ca, with or without putrescine added to the nutrient solution. Using metabolomics and proteomics analysis, we show that a significant part of the low-K response such as lower photosynthesis and N assimilation, is due to calcium and can be suppressed by low Ca conditions. Putrescine addition tends to restore photosynthesis and N assimilation but but aggravates the impact of low-K conditions on catabolism. We conclude that (i) effects of K deficiency can be partly alleviated by the use of low Ca and not only by K fertilization, and (ii) in addition to its role as a metabolite, putrescine participates in the regulation of the content in enzymes involved in carbon primary metabolism.

Detection of Sulphide Deposit Using Uranium/Potassium Ratio Map

Potassium (K) response is associated with minerals that can be easily weathered, whereas uranium (U) is usually related to residual clay, oxides and accessory minerals. With a view to interpret for the detection of sulphide deposit based on similar responses exhibited by the various rock units, radiometric data set was interpreted. The study area is located within Latitude +8000’00’’to +8030’00’’ and Longitude +5030’00’’E to +6000’00’’E. The data was collected in most parts of the Nigeria by Fugro Airborne Services Ltd. Johannesburg in collaboration with the Nigerian Geological Survey agency using a light aircraft that was flown in NW-SE direction with a nominal terrain clearance of 80 m and at a speed of 70-80 m/s, with a flight line spacing of 500 m apart. The acquired data was subjected to elemental concentration enhancement using Geosoft Oasis Montaj Software. From the interpreted data, the red coloured portions indicate high uranium and low potassium formations (H-U/K), while the blue coloured portions indicate low uranium and high potassium formations (L-U/K). The regions L-U/K have recorded low U/K ratios, meaning that L-U/K have very low uranium count rates as compared to the count rates of potassium in these regions; this signifies potassium abundance. This also suggests igneous activities that usually culminate to the emplacement of the meta-volcanic lithologies. H-U/K and M-U/K (Moderate U/K formations) are seen to have patches of high U/K ratios within the central portions. This high U/K ratio was therefore, as a result of sulphide deposition.

NBCe1-A is required for the renal ammonia and K+ response to hypokalemia

Hypokalemia increases ammonia excretion and decreases K+ excretion. The present study examined the role of the proximal tubule protein NBCe1-A in these responses. We studied mice with Na+-bicarbonate cotransporter electrogenic, isoform 1, splice variant A (NBCe1-A) deletion [knockout (KO) mice] and their wild-type (WT) littermates were provided either K+ control or K+-free diet. We also used tissue sections to determine the effect of extracellular ammonia on NaCl cotransporter (NCC) phosphorylation. The K+-free diet significantly increased proximal tubule NBCe1-A and ammonia excretion in WT mice, and NBCe1-A deletion blunted the ammonia excretion response. NBCe1-A deletion inhibited the ammoniagenic/ammonia recycling enzyme response in the cortical proximal tubule (PT), where NBCe1-A is present in WT mice. In the outer medulla, where NBCe1-A is not present, the PT ammonia metabolism response was accentuated by NBCe1-A deletion. KO mice developed more severe hypokalemia and had greater urinary K+ excretion during the K+-free diet than did WT mice. This was associated with blunting of the hypokalemia-induced change in NCC phosphorylation. NBCe1-A KO mice have systemic metabolic acidosis, but experimentally induced metabolic acidosis did not alter NCC phosphorylation. Although KO mice have impaired ammonia metabolism, experiments in tissue sections showed that lack of ammonia does impair NCC phosphorylation. Finally, urinary aldosterone was greater in KO mice than in WT mice, but neither expression of epithelial Na+ channel α-, β-, and γ-subunits nor of H+-K+-ATPase α1- or α2-subunits correlated with changes in urinary K+. We conclude that NBCe1-A is critical for the effect of diet-induced hypokalemia to increase cortical proximal tubule ammonia generation and for the expected decrease in urinary K+ excretion.

Potassium Response in some Malawi Soils

Potassium (K) response curves were generated for some Malawi soils using four different rates of potassium fertilizer, with grass being used to estimate plant availability. The study was conducted to find the point of maximum response for potassium. The soils were characterized, limed and fertilized with equal amounts of nitrogen. Potassium was applied at four rates: 0.0, 0.1, 0.2 and 0.4 me K/100 cm3 soil. The K treated soils were put in pots and cropped with grass. The grass was harvested six weeks after planting, dried and weighed. In general, addition of potassium resulted in increased growth of grass in all soils, with some soils showing better response than others. For montmorillonitic soils and soils with mixed mineralogy response was linear up to the highest rate of 0.4 me K/100 cm3. Apparently the 0.4 me K/100 cm3 soil was not enough to give maximum yield for these potassium depleted soils. For the kaolinitic soils 0.4 me K/100 cm3 soil was beyond point of maximum response. The variation of response to added potassium in the different soils calls for soil specific fertilizer additions. Smallholder farmers should move from blanket (crop specific) fertilizer recommendations currently being used to crop and soil specific fertilizer recommendations. Basal fertilizer dressings (starter packs) should always contain potassium. Correlation and calibration studies should be conducted to establish a potassium low optimum level for Malawi soils.

Recovery of Ubiquitous Multimedia Content Discovery Mobile Agent

Multimedia content is ubiquitous; therefore it is very difficult to bring all the hidden contents to the every one of universe. Mobile agent technology is the efficient technique to discover and bring the multimedia content to the universe with the help of dynamic itinerary movement. While mobile agent is roaming to discover the ubiquitous content, it has to go and visit multiple servers with different character in nature (that is server may be legitimate or hostile; hostile intention is to disturb the agent functionalities either by killing the agent or modifying the agent functionalities). Whenever the agent is disturbed (agent is altered or killed) by the hostile servers while roaming to discover the content, we should have the recovery mechanism to rollback the agent. This chapter adopts the K-response recovery model to rollback the original agent even then it is cracked or killed by the malicious servers while discovering the multimedia content.

The influence of melodic and rhythmic redundancies on recognition memory for unknown musical themes

The aim of this study was to assess the influence of melodic and rhythmic redundancies, and their interaction with tonality, on recognition memory for music. Forty-four non-musicians performed a recognition task with unknown musical material. Stimuli created for experimental purposes were made up of 48 short melodies (half tonal and half non-tonal) and were characterized by the presence of three kinds of musical redundancy: melodic only, rhythmic only, or both melodicrhythmic. In a first phase, subjects listened to a study list of 24 stimuli. After 20 minutes, a test list containing 48 stimuli (24 previously heard and 24 novel ones) was administered, and subjects were asked to indicate for each item whether the melody: was recognized from the study list (R response); evoked a sense of familiarity (K response); or was not recognized at all (X response). Major results showed that tonality influences semantic, but not episodic memory, and that the two systems are differentially affected by the type of redundancy (especially melodic-rhythmic, which has a large effect on episodic memory but is ineffective for semantic memory). Moreover, tonality and the type of redundancy systematically interact only in the episodic memory system. Thus, evidence supports disassociation of the two memory systems. Furthermore, R and X responses showed a symmetry in their trend, suggesting a role for X responses as counterparts of the R responses within the episodic memory system. Melodic-rhythmic redundancy demonstrated the most prominent effects on the episodic system, whereas the assessment comparing melodic versus rhythmic only as the pre-eminent type of redundancy was more ambiguous. Finally, non-tonal stimuli were found to be more sensitive than tonal stimuli, whereby they showed differential effectiveness regarding redundancy type, a result which suggests that they could prove serviceable in future studies concerning recognition memory for music.

FONIO MILLET (DIGITARIA EXILIS) RESPONSE TO N, P AND K FERTILIZERS UNDER VARYING CLIMATIC CONDITIONS IN WEST AFRICA

SUMMARYFonio millet (Digitaria exilis), a small-grained cereal, plays an important role in food security in West Africa. As part of efforts to increase its productivity, we studied the effects of moderate levels of nitrogen (0, 15.0 and 30.0 kg N ha−1), phosphorus (0, 6.6 and 13.2 kg P ha−1) and potash (0, 12.5 and 25.0 kg K ha−1) fertilizers under varying climatic conditions. The three experimental sites at Bareng and Bordo in Guinea, and Cinzana in Mali, are representative of the distribution of fonio millet in West Africa. The average recorded grain yields were 1.51 ± 0.229, 1.08 ± 0.141 and 0.47 ± 0.182 t ha−1 in Bareng, Bordo and Cinzana, respectively. We observed a marginal to significant impact of N fertilization coupled, in Bordo, with a significant interaction with the P and K response. This interaction was highlighted by the limited effect of N without P or K fertilization or with the application of only one of these two major elements. Overall, N application as low as 15 kg ha−1 led to a 12–22% increase in production if the P and K applications were not limited. For better control over the risks associated with poor soil fertility and limited rainfall, it appeared to be more effective to apply moderate levels of N, P and K fertilizers to the fonio millet crop than a large amount of one of these nutrients.