Five-year financial analysis of two commercial farms converting to organic: 2000-2005

The financial performance including input and output costs were analysed for two commercial Scottish farms converting to organic production. A comparative analysis for a five year period is provided using data from the Scottish Farm Accounts scheme, and demonstrates that both conversions had positive financial outcomes. Both farms applied strategic changes to their businesses

Stationary state volume fluctuations in a granular medium

A statistical description of static granular material requires ergodic sampling of the phase space spanned by the different configurations of the particles. We periodically fluidize a column of glass beads and find that the sequence of volume fractions phi of post-fluidized states is history independent and Gaussian distributed about a stationary state. The standard deviation of phi exhibits, as a function of phi, a minimum corresponding to a maximum in the number of statistically independent regions. Measurements of the fluctuations enable us to determine the compactivity X, a temperature-like state variable introduced in the statistical theory of Edwards and Oakeshott [Physica A {\bf 157}, 1080 (1989)].Comment: published with minor change

Quality of Runoff from Four Northwest Arkansas Pasture Fields Treated with Organic and Inorganic Fertilizer

Long-term land application of animal manures, even at agronomic rates, can promote accumulation of soil phosphorus (P) which can, in turn, contribute to increased P loadings to downstream waters. The objective of this study was to assess the soil and runoff effects of replacing animal manure as a soil amendment with inorganic fertilizer (ammonium nitrate, NH4NO3) on fields that had been treated previously with animal manures. Runoff from two pairs of small fields (0.57 to 1.46 ha) was sampled from September 1991 to April 1994. All fields had been treated previously with animal manures; after runoff monitoring began, one field of each pair received only NH4NO3, while the other of each pair continued to receive animal manure. Both soil and runoff P concentrations exhibited statistically significant decreasing trends over the monitoring period. The results demonstrate the potential for positively influencing runoff quality in a relatively short duration by replacing animal manures with ammonium nitrate for fields already having sufficient soil P

The differential absorption of a series of P-glycoprotein substrates in isolated perfused lungs from Mdr1a/1b genetic knockout mice can be attributed to distinct physico-chemical properties: an insight into predicting transporter-mediated, pulmonary specific disposition

Purpose To examine if pulmonary P-glycoprotein (P-gp) is functional in an intact lung; impeding the pulmonary absorption and increasing lung retention of P-gp substrates administered into the airways. Using calculated physico-chemical properties alone build a predictive Quantitative Structure-Activity Relationship (QSAR) model distinguishing whether a substrate’s pulmonary absorption would be limited by P-gp or not. Methods A panel of 18 P-gp substrates were administered into the airways of an isolated perfused mouse lung (IPML) model derived from Mdr1a/Mdr1b knockout mice. Parallel intestinal absorption studies were performed. Substrate physico-chemical profiling was undertaken. Using multivariate analysis a QSAR model was established. Results A subset of P-gp substrates (10/18) displayed pulmonary kinetics influenced by lung P-gp. These substrates possessed distinct physico-chemical properties to those P-gp substrates unaffected by P-gp (8/18). Differential outcomes were not related to different intrinsic P-gp transporter kinetics. In the lung, in contrast to intestine, a higher degree of non-polar character is required of a P-gp substrate before the net effects of efflux become evident. The QSAR predictive model was applied to 129 substrates including eight marketed inhaled drugs, all these inhaled drugs were predicted to display P-gp dependent pulmonary disposition. Conclusions Lung P-gp can affect the pulmonary kinetics of a subset of P-gp substrates. Physico-chemical relationships determining the significance of P-gp to absorption in the lung are different to those operative in the intestine. Our QSAR framework may assist profiling of inhaled drug discovery candidates that are also P-gp substrates. The potential for P-gp mediated pulmonary disposition exists in the clinic

Fact Sheet no.2: Water Quality and Poultry Disposal Pits

Disposing of poultry that die during grow out is a serious management problem for poultry producers in Northwest Arkansas and across the country. Poultry disposal can affect water quality and the health of wildlife, livestock and people

Fact Sheet no.1: Nonpoint Source Pollution and Water Quality of Northwest Arkansas

Preservation of a clean, safe, and biologically diverse environment can capture public attention as few other issues can. Indeed, recent international cooperative efforts indicate that there is an increasing global desire to pass on to future generations an environment at least equal in quality to the one we inherited

Indicator Bacteria Concentrations of Two Northwest Arkansas Streams in Relation to Flow and Season

Concentrations of indicator bacteria such as fecal coliform (FC) and fecal streptococcus (FS) are often used to assess the suitability of waters for their intended use(s) and to allocate resources for water quality improvement measures. There is evidence, however, that concentrations of FC and FS can be influenced by variables such as season and flow rate during sampling, which could lead to biased results. The objective of this study was to assess the impacts of season and flow rate on concentrations of FC and FS. Fecal indicator bacteria concentrations were measured for approximately three years at five sites on two Northwest Arkansas streams. Flow data were collected at two of the five sites. Land use in the basins draining the streams was primarily pasture (57-90%) and forest (6-40%). Significant seasonal influences on FC and FS concentrations were detected for all sampling sites, with the highest concentrations occurring in summer. On the two sites with flow data, flow rate generally had a significant effect on FC and FS concentrations during all seasons, with FC and FS concentrations increasing with flow rate. Ratios of FC and FS, which have been used in the past to differentiate between animal and human sources of fecal pollution, did not appear to reliably indicate the major sources of fecal indicator bacteria. The findings of this study suggest a potential for fixed sampling intervals to contribute to biased results. The issue of biased results might be avoided by sampling during times of year and flow conditions that support the intended use(s) of the waters

Effect of BMP Implementation on Storm Flow Quality of Two Northwestern Arkansas Streams

The effectiveness of management practices in improving quality of runoff from agricultural land areas has been reported based primarily on results from plot- and field-scale studies. There is limited information available on watershed scales, particularly when the dominant agricultural land use is pasture. The objective of this study was to determine whether a program of Best Management Practice (BMP) implementation in the Lincoln Lake watershed of northwestern Arkansas was effective in reducing storm stream flow concentrations and mass transport of nitrate nitrogen (NO3-N), ammonia nitrogen (NH3-N), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO4-P), total phosphorus (TP), chemical oxygen demand (COD), and total suspended solids (TSS). Storm flow quality of the two main tributaries to Lincoln Lake was monitored from September 1991 to April 1994. Significant decreases (from 23 to 75% per year) in both concentrations and mass transport of NO3-N, NH3-N, TKN, and COD occurred concurrently with BMP implementation. The decreases in nitrogen and COD concentrations and mass transport are attributed to BMP implementation, and the BMP most responsible for these decreases is most likely nutrient management

Computation vs. Experiment for High-Frequency Low-Reynolds Number Airfoil Plunge

We seek to extend the literature on sinusoidal pure-plunge of 2D airfoils at high reduced frequency and low Reynolds number, by including effects of camber and nonzero mean incidence angle. We compare experimental results in a water tunnel using dye injection and 2D particle image velocimetry, with a set of computations in 2D – Immersed Boundary Method and unsteady Reynolds-Averaged Navier Stokes. The Re range is from 10,000 to 60,000, based on free stream velocity and airfoil chord, chosen to cover cases where transition in attached boundary layers would be of some importance, and where transition would only occur in the wake. Generally at high reduced frequency there is no Reynolds number effect. Mean angle of attack has significance, notionally, depending on whether it is below or above static stall. Computations were found to agree well with experimentally-derived velocity contours, vorticity contours and momentum in the wake. As found previously for the NACA0012, varying Strouhal number is found to control the topology of the wake, while varying reduced amplitude and reduced frequency together, but keeping Strouhal number constant, causes wake vortical structures to scale with the reduced amplitude of plunge. Flowfield periodicity – as evinced from comparison of instantaneous and time-averaged particle image velocimetry – is generally attained after two periods of oscillation from motion onset