New implements for small farmers of the semi-arid tropics

A range of implements have been developed at ICRISAT for farmers in the semi-arid tropics. They include: Agribar II, used for various tillage operations and which can be fitted with a four-row planter, and simple T-bar bullock-drawn implements for making broadbeds, applying fertilizer, sowing and interrow cultivation; three different models of crust-breaker, covering one row, two rows and a metre-wide strip, to enhance the emergence of seedlings through the soil crust; a twin spinning-disc knapsack-sprayer for low-growing crops; a groundnut digger for hard soil, with chisel points to assist penetration; and a donkey-drawn cultivator-cum-seeder for sowing pearl millet and sorghum in hills and for interrow weeding on light-textured soils

Simulating Food Web Dynamics along a Gradient: Quantifying Human Influence

Realistically parameterized and dynamically simulated food-webs are useful tool to explore the importance of the functional diversity of ecosystems, and in particular relations between the dynamics of species and the whole community. We present a stochastic dynamical food web simulation for the Kelian River (Borneo). The food web was constructed for six different locations, arrayed along a gradient of increasing human perturbation (mostly resulting from gold mining activities) along the river. Along the river, the relative importance of grazers, filterers and shredders decreases with increasing disturbance downstream, while predators become more dominant in governing eco-dynamics. Human activity led to increased turbidity and sedimentation which adversely impacts primary productivity. Since the main difference between the study sites was not the composition of the food webs (structure is quite similar) but the strengths of interactions and the abundance of the trophic groups, a dynamical simulation approach seemed to be useful to better explain human influence. In the pristine river (study site 1), when comparing a structural version of our model with the dynamical model we found that structurally central groups such as omnivores and carnivores were not the most important ones dynamically. Instead, primary consumers such as invertebrate grazers and shredders generated a greater dynamical response. Based on the dynamically most important groups, bottom-up control is replaced by the predominant top-down control regime as distance downstream and human disturbance increased. An important finding, potentially explaining the poor structure to dynamics relationship, is that indirect effects are at least as important as direct ones during the simulations. We suggest that our approach and this simulation framework could serve systems-based conservation efforts. Quantitative indicators on the relative importance of trophic groups and the mechanistic modeling of eco-dynamics could greatly contribute to understanding various aspects of functional diversity

Soil management and production of alfisols in the semi-arid tropics. IV. Simulation of decline in productivity caused by soil erosion

Maintenance of a productive soil base by minimizing soil erosion is vital to long-term crop production. In this study, a modelling approach is used to estimate the effects of soil erosion on productivity for a sorghum cropping system on an Alfisol in the semi-arid tropics of India. Predictions of erosion, runoff and yield decline due to erosion, for variations in initial soil depth, slope, tillage strategy and amendment treatment, are presented. On average, soil depth decreased by 0.91 cm/year at Hyderabad for a 10% slope, 80 cm initial soil depth, shallow tillage at planting and no surface amendment. Rates of soil removal and subsequent yield decline were higher for shallower soils, steeper slopes and if management practices provided less surface cover during the crop. The productive life of the soil was less than 91 years for some soil depths, slope and management combinations. For other combinations, significant yield decline was predicted after 91 years of cropping. The quantification of erosion-productivity relationships allows us to identify regions with a higher risk of degradation from soil erosion and to estimate the impact of various management options on long-term sustainability. Models provide a basis to focus research and a means of assessing alternative management strategies to preserve long-term production

Parent and child agreement for acute stress disorder, post-traumatic stress disorder and other psychopathology in a prospective study of children and adolescents exposed to single-event trauma

Examining parent-child agreement for Acute Stress Disorder (ASD) and Post-Traumatic Stress Disorder (PTSD) in children and adolescents is essential for informing the assessment of trauma-exposed children, yet no studies have examined this relationship using appropriate statistical techniques. Parent-child agreement for these disorders was examined by structured interview in a prospective study of assault and motor vehicle accident (MVA) child survivors, assessed at 2-4 weeks and 6 months post-trauma. Children were significantly more likely to meet criteria for ASD, as well as other ASD and PTSD symptom clusters, based on their own report than on their parent's report. Parent-child agreement for ASD was poor (Cohen's κ = -.04), but fair for PTSD (Cohen's κ = .21). Agreement ranged widely for other emotional disorders (Cohen's κ = -.07-.64), with generalised anxiety disorder found to have superior parent-child agreement (when assessed by phi coefficients) relative to ASD and PTSD. The findings support the need to directly interview children and adolescents, particularly for the early screening of posttraumatic stress, and suggest that other anxiety disorders may have a clearer presentation post-trauma

Soil management and rroduction of alfisols in the semi-arid tropics. I. Modelling the effects of soil management on runoff and erosion

Techniques to simulate effects of surface cover and tillage on runoff and erosion are described. Data for 15 soil management treatments on an Alfisol in the semi-arid tropics, India, were used to modify existing procedures of runoff prediction using USDA runoff curve numbers. A relationship between surface cover and curve number was developed to account for the effects of surface cover on runoff. Impact of shallow or deep tillage was predicted using functions that relate curve number to cumulative rainfall since tillage. The derived relationships were applied to adjust curve number due to the effects of cover and tillage on a daily basis and were incorporated into the cropping systems model called PERFECT-IND. Results of model validation showed that PERFECT-IND explained between 71 and 91% of the variation in daily runoff volumes. The model also provided accurate predictions of average annual runoff ranging from 33 to 217 mm for the 15 soil management treatments. Runoff was reduced to a much greater extent by surface cover compared with surface roughness. Surface cover reduced runoff curve number by a maximum of 35 units. The maximum reduction in curve number due to surface roughness was 5 units for shallow tillage and 10 units for deep tillage. Erosion predictions were acceptable but the lack of erosion data for all years in the experimental data limits the confidence in model output. Model calibration and validation have provided a set of parameters that can be coupled with historical climate records to provide a long-term perspective of the effects of soil management on runoff and erosion. Keywords: simulation, model, runoff, water balance, curve number

Soil management and production of alfisols in the semi-arid tropics. III. Long-term effects on water conservation and production

A calibrated cropping systems model was used to provide long-term biophysical responses of various land managements at two differing semi-arid tropic environments in India. Organic based practices such as farmyard manure or straw amendments and perennial pastures reduced runoff by between 50 and 87%, and are optimum for in situ, water and soil conservation. A consequence of the reduced runoff was an increase in drainage below the root zone. Furthermore, the detrimental effects of cropping on high slopes and long slope lengths showed that it is not feasible to crop on slopes greater than 5%. Our study did not incorporate farmer preferences for land management, but the results can still be used as an integral part of decision making for optimum land management

Effect of Soil Management Practices on Runoff and Infiltration Processes of Hardsetting Alfisol in Semi-Arid Tropics

Alfisols oi Semi-Arid Tropics (SAT) are often chiiractcriscd as structurally unstable (EL-Swaify et 31.. 1905). Under the impact of raindrops the structural instability leads to formation of a seal on the surface. The surface seals rcducc infiltration and increase runoff (Moore, 1981 1. As a result, plant-available water in the profile gets reduced. In most of the SAT Alfisols crop yields arc constrained by the plant-available water

Soil management of alfisols for water conservation and utilization

Alfisols are abundarrt soils used for rainfed agrkulfure but have a wide rarrse of problrrtrs due lo lora irrfilfratiorr rates. We studied a ranse of soil and crop managemenl options (fillngc and muklring for anrtunl crops, a~rrl ~wrerrninl crolrs) t:, incrcase infiltration during 1989 and 1990. With annual crops sfraw ~rrul~.ahn d FYM trrulch reducrd runof by 52% ar~d1 7% reslwcfitrly compared to barc freatmenfs but tillage h d small and inconsislent effecfs. Perennial crops produced high rutaolf duritrg the esfahlisl~~rrepnetr iod in 1988 and sukquetrfly a wide range of response depending or1 flu foliage slructure of fire r.roj>. Tall groroirtg pererrnial pigeon pea did not reduce runoff compared lo crops with no surface amendment but llrc derrse, shorf, s~rrtrulitrg stylosarrthes harr~ata reduced runofl more than straw mulch. Reduction in runof will decrease soil erosion and nrny increme draitra~e by up to 200 nrm pcr year. This drainage is a mmsive potential resource for dcrp rooted crups or irrigation fro111 grou~ritiuafer. Sustairrnble agrkultural production a1 a wntershed scale will involve soil manageme71t lo increase irtftltrafion in rairrfed areas and exploitafion of cortscqurnt increases in groundwater resources by irrigation or deep roofed crops

Semi-Markov Graph Dynamics

In this paper, we outline a model of graph (or network) dynamics based on two ingredients. The first ingredient is a Markov chain on the space of possible graphs. The second ingredient is a semi-Markov counting process of renewal type. The model consists in subordinating the Markov chain to the semi-Markov counting process. In simple words, this means that the chain transitions occur at random time instants called epochs. The model is quite rich and its possible connections with algebraic geometry are briefly discussed. Moreover, for the sake of simplicity, we focus on the space of undirected graphs with a fixed number of nodes. However, in an example, we present an interbank market model where it is meaningful to use directed graphs or even weighted graphs.Comment: 25 pages, 4 figures, submitted to PLoS-ON

Dose-escalation study of a second-generation non-ansamycin HSP90 inhibitor, onalespib (AT13387), in combination with imatinib in patients with metastatic gastrointestinal stromal tumour

AbstractBackgroundGastrointestinal stromal tumours (GIST) treated with the tyrosine kinase inhibitor (TKI) imatinib can become resistant when additional mutations in the receptor tyrosine kinases KIT or PDGFRA block imatinib activity. Mutated KIT requires the molecular chaperone heat-shock protein 90 (HSP90) to maintain stability and activity. Onalespib (AT13387) is a potent non-ansamycin HSP90 inhibitor. We hypothesised that the combination of onalespib and imatinib may be safe and effective in managing TKI-resistant GIST.Patients and methodsIn this dose-escalation study, we evaluated the safety and efficacy of combination once-weekly intravenous onalespib for 3 weeks and daily oral imatinib in 28-d cycles. Twenty-six patients with TKI-resistant GIST were enrolled into four sequential dose cohorts of onalespib (dose range, 150–220 mg/m2) and imatinib 400 mg. The relationship between tumour mutational status (KIT/PDGFRA) and efficacy of treatment was explored.ResultsCommon onalespib-related adverse events were diarrhoea (58%), nausea (50%), injection site events (46%), vomiting (39%), fatigue (27%), and muscle spasms (23%). Overall, 81% of patients reported more than one onalespib-related gastrointestinal disorder. Nine patients (35%) had a best response of stable disease, including two patients who had KIT mutations known to be associated with resistance to imatinib and sunitinib. Disease control at 4 months was achieved in five patients (19%), and median progression-free survival was 112 d (95% confidence interval 43–165). One patient with PDGFRA-mutant GIST had a partial response for more than 376 d.ConclusionThe combination of onalespib plus imatinib was well tolerated but exhibited limited antitumour activity as dosed in this TKI-resistant GIST patient population.Trial registration ID: clinicaltrials.gov: NCT0129420