5,496 research outputs found
The effect of tyres and a rubber track at high axle loads on soil compaction-Part 2: Multi-axle machine studies
This paper reports on a study of the effect of the passage of multi-axle harvesting machines on the soil physical properties. In particular, it investigates the effect of the rear tyre of a combine harvester on the amount of soil compaction subsequent to the passage of the front tyre/track. The work was conducted in controlled laboratory conditions to determine the effect of a simulated self-propelled combine harvester with a total machine weight of 30â33 t. This was assessed by embedding talcum powder tracer lines in the soil to measure soil displacement and soil density changes. Dry bulk density and penetrometer resistance were also measured. The results showed that the benefit of the rubber track found by Ansorge and Godwin [2007a. The effect of tyres and a rubber track at high axle loads on soil compaction: Part 1: Single Axle Studies. Biosystems Engineering 98 (1), 115â126] was maintained after the additional passage of the rear tyre. After the passage of a track the effect of rear tyre size was insignificant, but the rear tyre size had a significant influence on soil density when following a leading tyre. This was due to a higher strength layer at the soil surface created by the track which was able to withstand the load of the subsequent passes and protect the soil below from further compaction. Results similar to those found for a tracked machine were also achieved by three passes of a 900 mm section width tyre at 5 t load and 0.5 bar inflation pressure. The track results for the 33 t machine were very similar to those of a smaller combine harvester with a total load of 11 t and similar rut width. The study confirmed the benefit of tracks with regard to soil compaction and emphasised the fact that total axle loads and machine weights are less important than how the loads are distributed to the soil
Phosphorus Release Characteristics from Biosolids-Derived Organomineral Fertilizers
This study investigated the availability of phosphorus (P) following soil application of a novel biosolids-derived organomineral fertilizer (OMF15; 15:4:4) in comparison with single superphosphate (0:18:0). Two soil types of contrasting characteristics were incubated over a period of 90 days at 25 °C and maintained near field capacity. Phosphorus was applied at rates equivalent to 0 (control), 150, and 300 kg haâ1 of P2O5, respectively. Availability of P from OMF15 was low throughout the experiment accounting for less than 6.5% of total OMF15-P applied. It was shown that after the 90 days incubation period, the overall increase in soil extractable P in OMF15-treated soil was marginal in both soil types. For single superphosphate (SSP), P availability ranged from 16% to 46% of total SSP-P applied. Application of SSP increased soil extractable P levels significantly (P < 0.001) compared with unfertilized control soils. The results of this study aided the development of fertilization strategies for the best use of OMF produced from nutrient-enriched biosolids granules for applications in winter cereal and grass crops in England
Nitrogen release characteristics from biosolids-derived organomineral fertilizers
is study investigated the availability of nitrogen (N) following soil application of a novel biosolids-derived organomineral fertilizer (OMF15â15:4:4) in comparison with urea (46% N). OMF15 is produced by coating biosolids granules (particle size range: 1.10â5.50 mm in diameter) with urea and potash [60% potassium oxide (K2O)], which increase the concentration of mineral N and potassium (K), respectively, resulting in a balanced fertilizer material suitable for application in cereal and grass crops. The study comprised two soil types of contrasting characteristics which were incubated over a period of 90 days at 25 °C and maintained near field capacity. Nitrogen was applied at rates equivalent to 0 (control), 150, and 300 kg haâ1, and soil mineral N measured routinely using standard laboratory techniques. Results showed that the majority of N was released from OMF15 within 30 days from application (range: 40% to 72% of total OMF15-N applied) with a further 10% to 28% in the following 60â90 days. OMF15 required an accumulated thermal time of 2250 degrees-day to release between 68% and 79% of the total OMF15-N applied. From this, it was inferred that mineralization of the organic-N fraction in OMF15 is likely to progress beyond harvest of winter cereal crops in-field conditions in England. The results of this study aided the development of fertilization strategies for the best use of OMF in winter cereal and grass crops
Detection of Non-Random Galaxy Orientations in X-ray Subclusters of the Coma Cluster
This study on the Coma cluster suggests that there are deviations from a
completely random galaxy orientation on small scales. Since we found a
significant coincidence of hot-gas features identified in the latest X-ray
observations of Coma with these local anisotropies, they may indicate regions
of recent mutual interaction of member galaxies within subclusters which are
currently falling in on the main cluster.Comment: 4 pages, 4 figures, 3 tables v2: Rewritten introduction, amendments
to the 'Interpretation' sectio
Testing and validating the CERES-wheat (Crop Estimation through Resource and Environment Synthesis-wheat) model in diverse environments
CERES-Wheat is a computer simulation model of the growth, development, and yield of spring and winter wheat. It was designed to be used in any location throughout the world where wheat can be grown. The model is written in Fortran 77, operates on a daily time stop, and runs on a range of computer systems from microcomputers to mainframes. Two versions of the model were developed: one, CERES-Wheat, assumes nitrogen to be nonlimiting; in the other, CERES-Wheat-N, the effects of nitrogen deficiency are simulated. The report provides the comparisons of simulations and measurements of about 350 wheat data sets collected from throughout the world
An investigation into the fertilizer particle dynamics off-the-disc
The particle size range specifications for two biosolids-derived organomineral fertilizers (OMF) known as OMF10 (10:4:4) and OMF15 (15:4:4) were established. Such specifications will enable field application of OMF with spinning disc systems using conventional tramlines spacing. A theoretical model was developed, which predicts the trajectory of individual fertilizer particles off-the-disc. The drag coefficient (Cd) was estimated for small time steps (10-6 s) in the trajectory of the particle as a function of the Reynolds number. For the range of initial velocities (20 to 40 m s-1), release angles (0Ă° to 10Ă°) and particle densities (1000 to 2000 kg m-3) investigated, the analysis showed that OMF10 and OMF15 need to have particle diameters between 1.10 and 5.80 mm, and between 1.05 and 5.50 mm, respectively, to provide similar spreading performance to urea with particle size range of 1.00 to 5.25 mm in diameter. OMF10 and OMF15 should have 80% (by weight) of particles between 2.65 and 4.30 mm, and between 2.55 and 4.10 mm, respectively. Due to the physical properties of the material, disc designs and settings that enable working at a specified bout width by providing a small upward particle trajectory angle (e.g., 10Ă°) are preferred to high rotational velocities. However, field application of OMF with spinning discs applicators may be restricted to tramlines spaced at a maximum of 24 m; particularly, when some degree of overlapping is required between two adjacent bouts. The performance of granular fertilizers can be predicted based on properties of the material, such as particle density and size range, using the contour plots developed in this study
A protocol for a randomised controlled trial of prefabricated versus customised foot orthoses for people with rheumatoid arthritis: the FOCOS RA trial [Foot Orthoses â Customised v Off-the-Shelf in Rheumatoid Arthritis]
Abstract Background Foot pain is common in rheumatoid arthritis and appears to persist despite modern day medical management. Several clinical practice guidelines currently recommend the use of foot orthoses for the treatment of foot pain in people with rheumatoid arthritis. However, an evidence gap currently exists concerning the comparative clinical- and cost-effectiveness of prefabricated and customised foot orthoses in people with early rheumatoid arthritis. Early intervention with orthotics may offer the best opportunity for positive therapeutic outcomes. The primary aim of this study is to evaluate the comparative clinical- and cost-effectiveness of prefabricated versus customised orthoses for reducing foot pain over 12Â months. Methods/design This is a multi-centre two-arm parallel randomised controlled trial comparing prefabricated versus customised orthoses in participants with early rheumatoid arthritis (<â2Â years disease duration). A total of 160 (a minimum of 80 randomised to each arm) eligible participants will be recruited from United Kingdom National Health Service Rheumatology Outpatient Clinics. The primary outcome will be foot pain measured via the Foot Function Index pain subscale at 12Â months. Secondary outcomes will include foot related impairments and disability via the Foot Impact Scale for rheumatoid arthritis, global functional status via the Stanford Health Assessment Questionnaire, foot disease activity via the Rheumatoid Arthritis Foot Disease Activity Index, and health-related quality of life at baseline, 6 and 12Â months. Process outcomes will include recruitment/retention rates, data completion rates, intervention adherence rates, and participant intervention and trial participation satisfaction. Cost-utility and cost-effectiveness analyses will be undertaken. Discussion Outcome measures collected at baseline, 6 and 12Â months will be used to evaluate the comparative clinical- and cost- effectiveness of customised versus prefabricated orthoses for this treatment of early rheumatoid arthritis foot conditions. This trial will help to guide orthotic prescription recommendations for the management of foot pain for people with early rheumatoid arthritis in future. Trial registration ISRCTN13654421. Registered 09 February 2016
An Economic analysis of the potential for precision farming in UK cereal production
The results from alternative spatial nitrogen application studies are analysed in economic terms and compared to the costs of precision farming hardware, software and other services for cereal crops in the UK. At current prices, the benefits of variable rate application of nitrogen exceed the returns from a uniform application by an average of ÂŁ22 haâ1 The cost of the precision farming systems range from ÂŁ5 to ÂŁ18 haâ1 depending upon the system chosen for an area of 250 ha. The benefits outweigh the associated costs for cereal farms in excess of 80 ha for the lowest price system to 200â300 ha for the more sophisticated systems. The scale of benefits obtained depends upon the magnitude of the response to the treatment and the proportion of the field that will respond. To be cost effective, a farmed area of 250 ha of cereals, where 30% of the area will respond to variable treatment, requires an increase in crop yield in the responsive areas of between 0·25 and 1.00 t haâ1 (at ÂŁ65 tâ1) for the basic and most expensive precision farming systems, respectively
Estimating Under Five Mortality in Space and Time in a Developing World Context
Accurate estimates of the under-5 mortality rate (U5MR) in a developing world
context are a key barometer of the health of a nation. This paper describes new
models to analyze survey data on mortality in this context. We are interested
in both spatial and temporal description, that is, wishing to estimate U5MR
across regions and years, and to investigate the association between the U5MR
and spatially-varying covariate surfaces. We illustrate the methodology by
producing yearly estimates for subnational areas in Kenya over the period 1980
- 2014 using data from demographic health surveys (DHS). We use a binomial
likelihood with fixed effects for the urban/rural stratification to account for
the complex survey design. We carry out smoothing using Bayesian hierarchical
models with continuous spatial and temporally discrete components. A key
component of the model is an offset to adjust for bias due to the effects of
HIV epidemics. Substantively, there has been a sharp decline in U5MR in the
period 1980 - 2014, but large variability in estimated subnational rates
remains. A priority for future research is understanding this variability.
Temperature, precipitation and a measure of malaria infection prevalence were
candidates for inclusion in the covariate model.Comment: 36 pages, 11 figure
CAIRNS: The Cluster And Infall Region Nearby Survey III. Environmental Dependence of H-alpha Properties of Galaxies
We investigate the environmental dependence of star formation in cluster
virial regions and infall regions as part of CAIRNS (Cluster And Infall Region
Nearby Survey), a large spectroscopic survey of the infall regions surrounding
nine nearby rich clusters of galaxies. Our long-slit spectroscopy yields
estimates of star formation rates in environments from cluster cores to the
general large-scale structure. The fraction of galaxies with current star
formation in their inner disks as traced by H-alpha emission increases with
distance from the cluster and converges to the ``field'' value only at 2-3
virial radii, in agreement with other investigations. However, among galaxies
with significant current star formation (EW[Ha]geq2\AA), there is no difference
in the distribution of EW[Ha] inside and outside the virial radius. This
surprising result, first seen by Carter et al., suggests that (1) star
formation is truncated on either very short timescales or only at moderate and
high redshifts or (2) that projection effects contaminate the measurement. The
number density profiles of star-forming and non-star-forming galaxies indicate
that, among galaxies projected inside the virial radius, at least half of the
former and 20% of the latter are ``infall interlopers,'' galaxies in the infall
region but outside the virial region. The kinematics of star-forming galaxies
in the infall region closely match those of absorption-dominated galaxies. This
result shows that the star forming galaxies in the infall regions are not
interlopers from the field and excludes one model of the backsplash scenario of
galaxy transformation. Finally, we quantify systematic uncertainties in
estimating the global star formation in galaxies from their inner disks.Comment: 25 pages, 21 figures, accepted for publication in A
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