P-FLUX: A phosphorus budget dataset spanning diverse agricultural production systems in the United States and Canada.

Quantifying spatial and temporal fluxes of phosphorus (P) within and among agricultural production systems is critical for sustaining agricultural production while minimizing environmental impacts. To better understand P fluxes in agricultural landscapes, P-FLUX, a detailed and harmonized dataset of P inputs, outputs, and budgets, as well as estimated uncertainties for each P flux and budget, was developed. Data were collected from 24 research sites and 61 production systems through the Long-term Agroecosystem Research (LTAR) network and partner organizations spanning 22 U.S. states and 2 Canadian provinces. The objectives of this paper are to (a) present and provide a description of the P-FLUX dataset, (b) provide summary analyses of the agricultural production systems included in the dataset and the variability in P inputs and outputs across systems, and (c) provide details for accessing the dataset, dataset limitations, and an example of future use. P-FLUX includes information on select site characteristics (area, soil series), crop rotation, P inputs (P application rate, source, timing, placement, P in irrigation water, atmospheric deposition), P outputs (crop removal, hydrologic losses), P budgets (agronomic budget, overall budget), uncertainties associated with each flux and budget, and data sources. Phosphorus fluxes and budgets vary across agricultural production systems and are useful resources to improve P use efficiency and develop management strategies to mitigate environmental impacts of agricultural systems. P-FLUX is available for download through the USDA Ag Data Commons (https://doi.org/10.15482/USDA.ADC/1523365).

Distribution of the Red Imported Fire Ant Solenopsis invicta (Hymenoptera: Formicidae) in Central Florida Pastures.

Habitat disturbance has been found to facilitate the introduction of a wide range of species, including the red imported fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae: Myrmicinae). Despite the link between S. invicta colonization and disturbance, little is known about how different intensities or types of disturbance might impact S. invicta populations. In this study, we used S. invicta populations in cattle pastures to understand how variation in disturbance type and frequency correlates with the density of S. invicta mounds. In total, 56 plots were surveyed for mound abundance during both the wet and dry seasons on a subtropical south Florida ranch. Explanatory variables were grouped into five categories based on disturbance type: 1) historic pasture conversion; 2) modern pasture management (mowing, dragging, chopping, or aerating); 3) grazing intensity (a measure vegetation height and dung pat abundance); 4) distance to human-made and natural localized disturbance (roads, ditches, and wetlands); and 5) abiotic conditions (soil temperature, soil moisture). Overall, the average number of mounds per plot was not significantly different between seasons, but was significantly higher in intensive pastures, which are converted to nonnative forage grasses than in seminative pastures during the dry season. Time since soil disturbance (aeration and chopping of pasture) was a significant predictor of S. invicta densities in both dry and wet seasons, with an increase in time since disturbance being associated with higher mound densities. Other forms of pasture management that did not disturb the soil, such as dragging and mowing, as well as distance to localized disturbances (wetlands, roads, and ditches) were not found to have a significant correlation in either season.

Evolving artificial neural networks for screening features from mammograms.

Disagreement or inconsistencies in mammographic interpretation motivates utilizing computerized pattern recognition algorithms to aid the assessment of radiographic features. We have studied the potential for using artificial neural networks (ANNs) to analyze interpreted radiographic features from film screen mammograms. Attention was given to 216 cases (mammogram series) that presented suspicious characteristics. The domain expert (Wasson) quantified up to 12 radiographic features for each case based on guidelines from previous literature. Patient age was also included. The existence or absence of malignancy was confirmed in each case via open surgical biopsy (111 malignant, 105 benign). ANNs of various complexity were trained via evolutionary programming to indicate whether or not a malignancy was present given a vector of scored input features in a statistical cross validation procedure. For suspicious masses, the best evolved ANNs generated a mean area under the receiver operating characteristic curve (AZ) of 0.9196 +/- 0.0040 (1 S.E.), with a mean specificity of 0.6269 +/- 0.0272 at 0.95 sensitivity. Results when microcalcifications were included were not quite as good (AZ = 0.8464), however, ANNs with only two hidden nodes performed as well as more complex ANNs and better than ANNs with only one hidden node. The performance of the evolved ANNs was comparable to prior literature, but with an order of magnitude less complexity. The success of small ANNs in diagnosing breast cancer offers the promise that suitable explanations for the ANN's behavior can be induced, leading to a greater acceptance by physicians.

Linear and neural models for classifying breast masses.

Computational methods can be used to provide an initial screening or a second opinion in medical settings and may improve the sensitivity and specificity of diagnoses. In the current study, linear discriminant models and artificial neural networks are trained to detect breast cancer in suspicious masses using radiographic features and patient age. Results on 139 suspicious breast masses (79 malignant, 60 benign, biopsy proven) indicate that a significant probability of detecting malignancies can be achieved at the risk of a small percentage of false positives. Receiver operating characteristic (ROC) analysis favors the use of linear models, however, a new measure related to the area under the ROC curve (AZ) suggests a possible benefit from hybridizing linear and nonlinear classifiers.

A step toward computer-assisted mammography using evolutionary programming and neural networks.

Artificial intelligence techniques can be used to provide a second opinion in medical settings. This may improve the sensitivity and specificity of diagnoses, as well as the cost effectiveness of the physician's effort. In the current study, evolutionary programming is used to train artificial neural networks to detect breast cancer using radiographic features and patient age. Results from 112 suspicious breast masses (63 malignant, 49 benign, biopsy proven) indicate that a significant probability of detecting malignancies can be achieved using simple neural architectures at the risk of a small percentage of false positives.

Evolving neural networks for detecting breast cancer.

Artificial neural networks are applied to the problem of detecting breast cancer from histologic data. Evolutionary programming is used to train the networks. This stochastic optimization method reduces the chance of becoming trapped in locally optimal weight sets. Preliminary results indicate that very parsimonious neural nets can outperform other methods reported in the literature on the same data. The results are statistically significant.

Development of a control strategy for Leptospira hardjo infection in a closed beef herd.

Serological evidence of infection with a leptospire belonging to the Sejroe serogroup was identified in a closed population of Luing cattle in the west of Scotland, and the geographical isolation of the population presented an opportunity to control and possibly eradicate the infection in a large beef herd farmed under extensive conditions. Serological and bacteriological studies revealed that infection was present at a high level throughout the herd, and that the infecting serovar was hardjo. Unlike endemic hardjo infection in dairy herds, new infections were still occurring in older age-groups. Investigations of other domestic and free-living species sharing the habitat demonstrated that the maintenance of an endemic focus of hardjo was restricted to the cattle. Changes in management to prevent the transmission of infection to successive cohorts of young animals were impractical and risky, and antibiotic treatment followed by removal to clean pasture failed to prevent new cases. Thus vaccination offered the only means of control and possible eradication, and the epidemiological characteristics of the infection dictated that the programme be applied to the whole herd.

A mild outbreak of bovine mastitis associated with Mycoplasma bovigenitalium.

Mycoplasma bovigenitalium was isolated from milk samples from 16 of 99 cows on one farm during a 15-week period in the summer of 1986. One cow was severely affected, four cows had relatively mild signs of mastitis, and three had only altered dry-cow udder secretions. Eleven of the infected cows were dry and three had been calved less than 48 hours. The abrupt method of drying-off and improvements in cleaning of the milking equipment were introduced, but no other control measures were instituted to eradicate the mycoplasma infections. After this mild outbreak of mastitis the herd was monitored for the next 17 months. In total 19 cows had a mycoplasma isolated from udder secretions. Acholeplasmas were isolated from 14 cows but were not associated with clinical mastitis. The udder infections with mycoplasmas apparently resolved without resorting to the segregation and culling of infected animals.

Experimental infection of pregnant ewes with Listeria monocytogenes.

Eight 18-month-old ewes were infected orally with Listeria monocytogenes between 77 and 91 days of pregnancy. Only one ewe aborted, 10 days after the first infecting dose, at 94 days of gestation; L monocytogenes was isolated from several sites in both its aborted fetuses. Two days after the first infecting dose all the ewes exhibited mild illness and pyrexia lasting for two to three days but the ewe which aborted was seriously ill until nine to 10 days after aborting. Agglutination tests carried out on 2-mercaptoethanol reduced sera revealed a strong immunological response in all the infected ewes but in the ewe which aborted this response was delayed. Four uninfected ewes which were kept as controls remained healthy throughout the experiment and showed no evidence of 2-mercaptoethanol resistant antibodies to L monocytogenes. Growth retardation lines, occurring at the time of and after experimental infection, were found in the bones of 14 of 17 newborn lambs in both the infected and control groups; in the aborted lambs these lines occurred before the infection.

Eradication of Mycoplasma bovis infection from a dairy herd in Great Britain.

Mycoplasma bovis infection was eradicated from a naturally infected dairy herd in Great Britain by a programme of identification, segregation and culling of infected animals. A series of group and whole milking herd tests was carried out over a period of 15 months, followed by a whole herd nasal swabbing. Cows were also sampled after calving and at drying off and bulk tanks were sampled at weekly intervals during the same period and for a further nine months. Fifty-nine cows were identified as excretors, the majority in group or herd tests, but five after calving and three at drying off. Eight of the original clinical cases were retained in the herd, after repeated negative test results. Bulk tank sampling was found to be extremely useful in detecting infection even down to one cow in a milking herd of 300. The value of milking hygiene and the indications for eradication are also discussed.

Effect of serial passages through liquid medium on the virulence of Mycoplasma bovis for the mouse mammary gland.

The mouse mastitis model was used to examine strains of Mycoplasma bovis. Strains that had been passaged in liquid medium more than 60 times were markedly less virulent than the same or different strains with fewer passages. Whereas the low passage strains produced a systemic response in some mice and severe pathological and histopathological changes in the mammary glands of all, the high passage strains produced only minor histopathological changes.

Studies on the effect of growth medium composition on the antigenicity of Mycoplasma bovis.

Serum proteins adsorbed from the culture medium were detected in Mycoplasma bovis antigens, the number and type of proteins depending on the serum used in the medium. The alpha-globulins cross-reacted with alpha-globulins from different types of sera but the gamma-globulins did not. The removal of non-specific medium antibodies by absorption showed that they affected the gel diffusion and growth precipitation tests, producing cross-reactions between M. bovis and M. bovigenitalium, but that the complement fixation, tube agglutination, and growth inhibition tests were not similarly affected. The presence of serum proteins in the antigens changed their specific reactivity in all the tests. The production of antibodies to serum proteins was increased by the use of an adjuvant, but it appeared that production of specific antibodies to the mycoplasmas was not.