Floodplain ecosystem response to climate variability and land-cover and land-use change in Lower Missouri River basin     

Yuyan C. Jordan  Abduwasit Ghulam  Robert B. Herrmann 《Landscape Ecology》2012,27(6):843-857

This contribution aims at characterizing the extreme responses of Lower Missouri River basin ecosystems to land use modification and climate change over a 30-year temporal extent, using long term Landsat data archives spanning from 1975 to 2010. The inter-annual coefficient of variation (CoV) of normalized difference vegetation index was used as a measure of vegetation dynamics to address ecological consequences associated with climate change and the impact of land-cover/land-use change. The slope of a linear regression of inter-annual CoV over the entire time span was used as a sustainability indicator to assess the trend of vegetation dynamics from 1975 to 2010. Deduced vegetation dynamics were then associated with precipitation patterns, land surface temperature, and the impact of levees on alluvial hydrologic partitioning and river channelization reflecting the links between society and natural systems. The results show, a higher inter-annual accumulated vegetation index, and lower inter-annual CoV distributed over the uplands remaining virtually stable over the time frame investigated; relatively low vegetation index with larger CoV was observed over lowlands, indicating that climate change was not the only factor affecting ecosystem alterations in the Missouri River floodplain. We cautiously conclude that river channelization, suburbanization and agricultural activities were the possible potential driving forces behind vegetation cover alteration and habitat fragmentation on the Lower Missouri River floodplain.  相似文献   

Surveillance of verocytotoxigenic Escherichia coli in Irish bovine dairy herds     

Lynch MJ  Fox EM  O'Connor L  Jordan K  Murphy M 《Zoonoses and public health》2012,59(4):264-271

Verocytotoxigenic Escherichia coli (VTEC) are highly significant zoonotic threats to public health, and have been the causative agent implicated in numerous high-profile outbreaks affecting large numbers of people. Serovar O157 is most frequently linked with human illness; however, other serovars, such as O26, O103, O111 and O145, have also been implicated. This study aimed to characterize the prevalence and virulence determinants of these five serovars in Irish dairy farm herds, and their milk. Using real-time PCR (RTi-PCR), bovine rectal faecal swabs and raw milk samples, along with milk filters, were screened for the presence of vt genes. Positive samples were then screened for the five serovars using sero-specific PCR. Serovar-positive samples were subjected to immunomagnetic separation, to isolate viable VTEC strains. These isolates were subsequently screened for four virulence factors: vt1, vt2, eaeA and hlyA. Three hundred and eighty six of the 600 rectal faecal swabs, 85 of the 117 milk-filters and 43 of the 120 bulk-tank milk samples, were positive for vt genes. From these 514 total vt-positive samples, 58 O26, 162 O103, 1 O111, 324 O145 and 26 O157 positives were detected by sero-specific RTi-PCR. Immunomagnetic separation yielded 12 O26, 26 O103, 0 O111, 19 O145 and 10 O157 isolates. Ten of these isolates contained at least one of the four virulence determinants screened for (i.e. vt1, vt2, eaeA and hlyA). Of these 10 isolates, pulsed-field gel electrophoresis showed that two of the O26 isolates from different farms were indistinguishable. Two O157 isolates were also indistinguishable. This study found serovars O103 and O145 to be the most prevalent in samples tested. Apart from the occurrence of VTEC in dairy herds, this study shows a high occurrence of vt genes in the environment, creating the possibility of horizontal gene transfer and emergence of new VTEC strains.  相似文献   

Modeling the effect of initial planting density on within tree variation of stiffness in loblolly pine     

Finto Antony  Laurence R. Schimleck  Lewis Jordan  Richard F. Daniels  Alex Clark III 《Annals of Forest Science》2012,69(5):641-650

Context

Modulus of elasticity (MOE) is an important mechanical property determining the end-use and value of loblolly pine (Pinus taeda L.) lumber.

Aim

In this study, a model was developed to predict the within tree variation of MOE, from pith-to-bark and stump-to-tip, using data collected from a 21-year-old unthinned stand where trees were planted under seven initial stand density levels (746?C2,243 trees/hectare).

Methods

The study was laid out in a randomized complete block design, with seven levels of initial planting density, replicated three times. Seven trees were destructively sampled from each plot, and bolts were cut from each tree at heights of 2.4, 7.3, and 12.2?m. Static bending samples (of dimension 2.5?×?2.5?×?40.6?cm) representing pith-to-bark variation were cut from each bolt and MOE measured. A three-parameter logistic function was used to model the pith-to-bark variation in stiffness with distance from pith as an explanatory variable.

Results

Based on the final fitted model, it was found that the asymptotic parameter (maximum outerwood MOE?=?13.48?GPa) was not influenced by sampling height, initial planting density, and stem slenderness. However, the inflection and scale parameters were significantly influenced by these variables.

Conclusions

In summary, we found that initial planting density had a significant influence on the amount of corewood produced with higher initial planting densities producing a lower proportion of corewood as indicated by a linear decrease in inflection point with an increase in planting density.  相似文献   

Control of Estrus and Ovulation in Beef Heifers     

David J. Patterson  PhD  Jordan M. ThomasNeal T. Martin  MS  Justin M. Nash  Michael F. Smith 《Veterinary Clinics of North America: Food Animal Practice》2013

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Segmental axonopathy of Merino sheep in New Zealand     

RD Jolly  AC Johnstone  SD Williams  K Zhang  TW Jordan 《New Zealand veterinary journal》2013,61(5):210-217

AIM: To investigate an axonopathy of Merino sheep that caused progressive hindlimb ataxia and slight to moderate paresis, with the purpose of understanding its pathogenesis.

METHODS: Tissues were fixed in buffered paraformaldehyde or paraformaldehyde and glutaraldehyde, processed into wax and epoxy resin, respectively, and examined by light and electron microscopy. Fresh frozen spinal cord and trigeminal nerve roots were subjected to homogenisation, centrifugation and two-dimensional electrophoresis. Selected protein spots were identified using matrix-assisted laser desorption ionisation (MALDI) mass spectrometry.

RESULTS. By light microscopy, there were large pale foamy spheroidal axonal swellings affecting peripheral as well as central axons. By electron microscopy, these were shown to contain many membrane-bound vesicles. The main abnormalities in expressed proteins involved cytoskeletal elements and myosin heavy chain, the latter interpreted as associated with the molecular motor myosin Va.

CONCLUSIONS: The disorder is the same as that described in Merinos in Australia as segmental axonopathy, and believed to have an inherited aetiology. The lesions and protein changes indicate abnormalities of the cytoskeleton, its relationship with the myelin sheath, and myosin Va molecular motor. The consequence appears to be abnormal axonal transport and inability to maintain the integrity of axons and their myelin sheaths.  相似文献   

An economic feasibility assessment of autonomous field machinery in grain crop production     

Shockley  Jordan M.  Dillon  Carl R.  Shearer  Scott A. 《Precision Agriculture》2019,20(5):1068-1085

Precision Agriculture - A multi-faceted whole farm planning model is developed to compare conventional and autonomous machinery for grain crop production under various benefit, farm size, suitable...  相似文献   

Integrating animal movement with habitat suitability for estimating dynamic migratory connectivity     

Mariëlle L. van Toor  Bart Kranstauber  Scott H. Newman  Diann J. Prosser  John Y. Takekawa  Georgios Technitis  Robert Weibel  Martin Wikelski  Kamran Safi 《Landscape Ecology》2018,33(6):879-893

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Development of a method for Bayesian nonparametric ROC analysis with application to an ELISA for Johne's disease in dairy cattle   总被引：2，自引：1，他引：1  

Fosgate GT  Scott HM  Jordan ER 《Preventive veterinary medicine》2007,81(1-3):178-193

Six hundred and sixty-eight dairy cattle were tested for Johne's disease using a direct-fecal real-time polymerase chain reaction (rt-PCR), fecal culture, and serum enzyme-linked immunosorbent assay (ELISA). Likelihood ratios (LRs) were estimated for five categories of sample-to-positive (S/P) values for the ELISA: <0.1, 0.1-0.249, 0.25-0.399, 0.4-0.999, > or =1.0. The statistical method assumed a single multinomial model for cross-classified rt-PCR, fecal culture results, and ELISA category strata. Conditional dependence between tests was investigated by the inclusion of all possible pairwise dependence terms. Sensitivity covariance between ELISA and fecal culture was estimated as 0.017. Estimates for the accuracy of the ELISA at the usual cutoff of 0.25S/P was 67.2% and 95.2% for sensitivity and specificity, respectively for a model that adjusted for the dependence between ELISA and fecal culture. The area under the receiver-operating characteristic (ROC) curve (95% probability interval) for the ELISA was 0.867 (0.796, 0.928). Point estimates for likelihood ratios (95% probability intervals) were 0.24 (0.11, 0.38), 1.52 (0.48, 3.27), 2.49 (0.31, 13.4), 6.33 (2.54, 16.5), and 103 (25.0, 2412) for the categories <0.1, 0.1-0.249, 0.25-0.399, 0.4-0.999, >/=1.0, respectively. Assumptions concerning the underlying distribution of test results for infected and uninfected animals were not necessary and this model can be employed for the general estimation of LRs and ROC curves in absence of knowledge concerning true disease status.  相似文献   

A simulation model for studying the role of pre-slaughter factors on the exposure of beef carcasses to human microbial hazards.     

D Jordan  S A McEwen  A M Lammerding  W B McNab  J B Wilson 《Preventive veterinary medicine》1999,41(1):37-54

A Monte Carlo simulation model was constructed for assessing the quantity of microbial hazards deposited on cattle carcasses under different pre-slaughter management regimens. The model permits comparison of industry-wide and abattoir-based mitigation strategies and is suitable for studying pathogens such as Escherichia coli O157:H7 and Salmonella spp. Simulations are based on a hierarchical model structure that mimics important aspects of the cattle population prior to slaughter. Stochastic inputs were included so that uncertainty about important input assumptions (such as prevalence of a human pathogen in the live cattle-population) would be reflected in model output. Control options were built into the model to assess the benefit of having prior knowledge of animal or herd-of-origin pathogen status (obtained from the use of a diagnostic test). Similarly, a facility was included for assessing the benefit of re-ordering the slaughter sequence based on the extent of external faecal contamination. Model outputs were designed to evaluate the performance of an abattoir in a 1-day period and included outcomes such as the proportion of carcasses contaminated with a pathogen, the daily mean and selected percentiles of pathogen counts per carcass, and the position of the first infected animal in the slaughter run. A measure of the time rate of introduction of pathogen into the abattoir was provided by assessing the median, 5th percentile, and 95th percentile cumulative pathogen counts at 10 equidistant points within the slaughter run. Outputs can be graphically displayed as frequency distributions, probability densities, cumulative distributions or x-y plots. The model shows promise as an inexpensive method for evaluating pathogen control strategies such as those forming part of a Hazard Analysis and Critical Control Point (HACCP) system.  相似文献   

Virucidal effects of various agents—including protease—against koi herpesvirus and viral haemorrhagic septicaemia virus     

Anette Amtmann  Ibrahim Ahmed  Petra Zahner-Rimmel  Adam Mletzko  Lisa Katharina Jordan  Martin Oberle  Helmut Wedekind  Jürgen Christian  Sven Michael Bergmann  Anna Maria Becker 《Journal of fish diseases》2020,43(2):185-195

In a search for alternative, environmentally friendly and effective disinfecting agents, a commercially available protease—Neutrase^®—was tested in this work for inactivation of koi herpesvirus (KHV) and of viral haemorrhagic septicaemia virus (VHSV). For comparison, the stability of these viral pathogens in similar configurations at various pH values and concentrations of peracetic acid or quicklime, typically used for disinfection, was tested. Therefore, virus suspensions were incubated with various concentrations of different agents for 24 hr and the titre of the remaining infectious particles was determined by virus titration. Furthermore, the treatment of both viruses, with the agents at concentrations that were previously appointed as effective, was also examined in the presence of solid material (quartz sand). All procedures investigated in this study, including the protease treatment, were able to reduce the titre of KHV and VHSV below the detection limit of the titration. Although further studies are necessary, this is the first report of the application of a protease for the inactivation of the selected fish pathogens, demonstrating the great potential of the latter for disinfection.  相似文献