Field Control of Avian Reoviruses in Commercial Broiler Production

Prevention of tenosynovitis/viral arthritis caused by variant avian reoviruses within commercial broiler production has become increasingly more challenging because of the lack of protection afforded by the current commercially available vaccines. Avian reoviruses isolated from clinical cases of tenosynovitis/viral arthritis in recent years are antigenically distinct from nearly all of the commercially licensed modified live and inactivated biologics available in the United States. The emergence of new variants is likely shaped by a lack of homologous protection coupled with selection pressure influences and results in antigenically diverse populations of avian reoviruses. One tool available to the poultry industry is the use of autogenous (custom) vaccines. Although these can be effective, isolation, characterization, and screening of isolates from clinical cases is paramount for the selection of isolates to include in these vaccines. With no treatment options, control can only be attained via prevention of infection. To achieve this goal, commercially licensed products with antigenic applicability and broadly cross-protective vaccine strains are needed.

Primary Mode of Action of the Novel Sulfonamide Fungicide against Botrytis cinerea and Field Control Effect on Tomato Gray Mold

Botrytis cinerea is considered an important plant pathogen and is responsible for significant crop yield losses. With the frequent application of commercial fungicides, B. cinerea has developed resistance to many frequently used fungicides. Therefore, it is necessary to develop new kinds of fungicides with high activity and new modes of action to solve the increasingly serious problem of resistance. During our screening of fungicide candidates, one novel sulfonamide compound, N-(2-trifluoromethyl-4-chlorphenyl)-2-oxocyclohexyl sulfonamide (L13), has been found to exhibit good fungicidal activity against B. cinerea. In this work, the mode of action of L13 against B. cinerea and the field control effect on tomato gray mold was studied. L13 had good control against B. cinerea resistant to carbendazim, diethofencarb, and iprodione commercial fungicides in the pot culture experiments. SEM and TEM observations revealed that L13 could cause obvious morphological and cytological changes to B. cinerea, including excessive branching, irregular ramification or abnormal configuration, and the decomposition of cell wall and vacuole. L13 induced more significant electrolyte leakage from hyphae than procymidone as a positive control. L13 had only a minor effect on the oxygen consumption of intact mycelia, with 2.15% inhibition at 50 μg/mL. In two locations over 2 years, the field control effect of L13 against tomato gray mold reached 83% at a rate of 450 g ai ha⁻¹, better than the commercial fungicide of iprodione. Moreover, toxicological tests demonstrated the low toxicological effect of L13. This research seeks to provide technical support and theoretical guidance for L13 to become a real commercial fungicide.

Feedback field control improves the precision of T2 * quantification at 7 T

T₂ * mapping offers access to a number of important structural and physiological tissue parameters. It is robust against RF field variations and overall signal scaling. However, T₂ * measurement is highly sensitive to magnetic field errors, including perturbations caused by breathing motion at high baseline field. The goal of this work is to assess this issue in T₂ * mapping of the brain and to study the benefit of field stabilization by feedback field control. T₂ * quantification in the brain was investigated by phantom and in vivo measurements at 7 T. Repeated measurements were made with and without feedback field control using NMR field sensing and dynamic third-order shim actuation. The precision and reliability of T₂ * quantification was assessed by studying variation across repeated measurements as well as fitting errors. Breathing effects were found to introduce significant error in T₂ * mapping results. Field control mitigates this problem substantially. In a phantom it virtually eliminates the effects of emulated breathing fluctuations in the head. In vivo it enhances the structural fidelity of T₂ * maps and reduces fitting residuals along with standard deviation. In conclusion, feedback field control improves the fidelity of T₂ * mapping in the presence of field perturbations. It is an effective means of countering bulk susceptibility effects of breathing and hence holds particular promise for efforts to leverage high field for T₂ * studies in vivo.

Laboratory and field evaluation of an entomopathogenic fungus, Isaria cateniannulata strain 08XS-1, against Tetranychus urticae (Koch)

BACKGROUND

The two-spotted mite, Tetranychus urticae Koch, is one of the most serious mite pests of crops throughout the world. Biocontrol of the mite with fungal agents has long been paid much attention because of the development of insecticide resistance and the severe restriction of chemical pesticides. In this study, the efficacy of submerged conidia of the entomopathogenic fungus Isaria cateniannulata strain 08XS-1 against T. urticae eggs, larvae and female adults was evaluated at different temperatures and humidity in the laboratory and under field conditions.

RESULTS

The results showed that a suspension of 2 × 10(7) submerged conidia mL(-1) caused the highest mortalities of mite eggs, larvae and females (100, 100 and 70% respectively) at 100% relative humidity and 25 °C in the laboratory. In the field experiments against the mites, a suspension of 2 × 10(8) submerged conidia mL(-1) achieved significant efficiency - the relative control effects were 88.6, 83.8 and 83%, respectively, in cucumber, eggplant and bean fields after 10 days of treatment.

CONCLUSION

The results suggest that the I. cateniannulata strain 08XS-1 is a potential fungal agent, with acceptable production cost of conidia, against T. urticae in the field in an area such as southwestern China with higher air humidity.

Real-time feedback for spatiotemporal field stabilization in MR systems

PURPOSE

MR imaging and spectroscopy require a highly stable, uniform background field. The field stability is typically limited by hardware imperfections, external perturbations, or field fluctuations of physiological origin. The purpose of the present work is to address these issues by introducing spatiotemporal field stabilization based on real-time sensing and feedback control.

METHODS

An array of NMR field probes is used to sense the field evolution in a whole-body MR system concurrently with regular system operation. The field observations serve as inputs to a proportional-integral controller that governs correction currents in gradient and higher-order shim coils such as to keep the field stable in a volume of interest.

RESULTS

The feedback system was successfully set up, currently reaching a minimum latency of 20 ms. Its utility is first demonstrated by countering thermal field drift during an EPI protocol. It is then used to address respiratory field fluctuations in a T2 *-weighted brain exam, resulting in substantially improved image quality.

CONCLUSION

Feedback field control is an effective means of eliminating dynamic field distortions in MR systems. Third-order spatial control at an update time of 100 ms has proven sufficient to largely eliminate thermal and breathing effects in brain imaging at 7 Tesla.