Agricultural management and plant selection interactively affect rhizosphere microbial community structure and nitrogen cycling.

BACKGROUND:Rhizosphere microbial communities are key regulators of plant performance, yet few studies have assessed the impact of different management approaches on the rhizosphere microbiomes of major crops. Rhizosphere microbial communities are shaped by interactions between agricultural management and host selection processes, but studies often consider these factors individually rather than in combination. We tested the impacts of management (M) and rhizosphere effects (R) on microbial community structure and co-occurrence networks of maize roots collected from long-term conventionally and organically managed maize-tomato agroecosystems. We also explored the interaction between these factors (M × R) and how it impacts rhizosphere microbial diversity and composition, differential abundance, indicator taxa, co-occurrence network structure, and microbial nitrogen-cycling processes. RESULTS:Host selection processes moderate the influence of agricultural management on rhizosphere microbial communities, although bacteria and fungi respond differently to plant selection and agricultural management. We found that plants recruit management-system-specific taxa and shift N-cycling pathways in the rhizosphere, distinguishing this soil compartment from bulk soil. Rhizosphere microbiomes from conventional and organic systems were more similar in diversity and network structure than communities from their respective bulk soils, and community composition was affected by both M and R effects. In contrast, fungal community composition was affected only by management, and network structure only by plant selection. Quantification of six nitrogen-cycling genes (nifH, amoA [bacterial and archaeal], nirK, nrfA, and nosZ) revealed that only nosZ abundance was affected by management and was higher in the organic system. CONCLUSIONS:Plant selection interacts with conventional and organic management practices to shape rhizosphere microbial community composition, co-occurrence patterns, and at least one nitrogen-cycling process. Reframing research priorities to better understand adaptive plant-microbe feedbacks and include roots as a significant moderating influence of management outcomes could help guide plant-oriented strategies to improve productivity and agroecosystem sustainability

Longitudinal transactional relationships between caregiver and child mental health during the COVID-19 global pandemic

Background Emerging work examining the psychological impact of COVID-19 on children and families suggests that the relationship between pandemic-related stress, child psychosocial functioning, and caregiver mental health are interrelated. However, much of this research is unidirectional and thus little is known about the bidirectional cascading effects children and caregivers may experience. The current study examined the transactional relationships between caregiver and child mental health over time during the COVID-19 pandemic. Methods Linguistically, racially, and ethnically diverse caregivers (N = 286) of young children completed measures of caregiver mental health, caregiver pandemic-related stress, and child mental health (i.e., externalizing, internalizing, prosocial behavior) across three time points in the spring of 2020. Results Using autoregressive cross-lagged analyses, impaired caregiver mental health at Time 1 (April 2020) predicted increased caregiver pandemic-related stress at Time 2 (May 2020). Caregiver pandemic-related stress at Time 1 predicted increased child internalizing symptoms at Time 2 which, in turn, predicted increased caregiver pandemic-related stress at Time 3 (July 2020). Lastly, impaired caregiver mental health at Time 2 (May 2020) predicted increased child externalizing symptoms at Time 3 (July 2020). Conclusions Assessing transactional relationships between child and caregiver mental health during the COVID-19 pandemic is important to inform models of risk and resilience. Interventions at the level of the caregiver, the child, and/or the family should be considered as a way to interrupt potential negative developmental cascades

The Effects of Heavy Backpack Carriage on Hand Strength

Force production in upper limb muscles could be affected following exercise that involves carrying a heavy backpack load. In lower limb muscles, previous study has demonstrated that there is muscle force depression after several different regimens of metabolically and mechanically demanding exercise. PURPOSE: The aim of this study is to examine pinch strength after exercising while carrying a heavy backpack with straps that compress the nerves and blood vessels of the upper limb. We hypothesized that backpack load carriage at 15% body weight and 30% body weight will lead to changes in upper limb lateral pinch strength as compared to a no-load condition. METHODS: To date, eleven participants (5 female, 6 male; mean ± SD of 25.8 ± 6.3 yrs, 81.9 ± 18 kg mass, 11 right handed) have completed 3 load conditions on separate days: 1) no backpack, 2) 15% body weight (BW) backpack, and 3) 30% BW backpack. Load condition order was randomized. Maximum lateral pinch strength was measured bilaterally using a pinch dynamometer before and after participants walked on a treadmill at 1.1 m/s for 30 minutes for each load condition. Pinch strength was measured every 5 minutes for 30 minutes after exercise. RMANOVA with Bonferroni post-hoc testing was used to compare among backpack conditions and among timepoints. RESULTS: Mean pinch strength on the dominant hand before backpack carriage was 10.8 ± 2.7 kg for male participants and 8.0 ± 1.2 kg for female participants. Pinch strength on the non-dominant hand before load carriage averaged 9.9 ± 1.7 kg for male participants and 7.5 ± 1.0 kg for female participants. Mean pinch strength on the dominant hand after 30% BW backpack carriage ranged from 10.6-10.9 kg for male participants and from 7.8 - 8.3 kg for female participants. There were no significant differences in pinch strength on either hand when comparing among backpack load conditions or timepoints for male or female participants. CONCLUSION: The compression of backpack straps and the exercise of walking with a backpack load did not affect pinch strength in the first 30 minutes after backpack carriage

Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end

Real Time Enzyme Inhibition Assays Provide Insights into Differences in Binding of Neuraminidase Inhibitors to Wild Type and Mutant Influenza Viruses

The influenza neuraminidase (NA) inhibitors zanamivir, oseltamivir and peramivir were all designed based on the knowledge that the transition state analogue of the cleaved sialic acid, 2-deoxy,2,3-dehydro N-acetyl neuraminic acid (DANA) was a weak inhibitor of NA. While DANA bound rapidly to the NA, modifications leading to the improved potency of these new inhibitors also conferred a time dependent or slow binding phenotype. Many mutations in the NA leading to decreased susceptibility result in loss of slow binding, hence this is a phenotypic marker of many but not all resistant NAs. We present here a simplified approach to determine whether an inhibitor is fast or slow binding by extending the endpoint fluorescent enzyme inhibition assay to a real time assay and monitoring the changes in IC50s with time. We carried out two reactions, one with a 30 min preincubation with inhibitor and the second without. The enzymatic reaction was started via addition of substrate and IC50s were calculated after each 10 min interval up to 60 min. Results showed that without preincubation IC50s for the wild type viruses started high and although they decreased continuously over the 60 min reaction time the final IC50s remained higher than for pre-incubated samples. These results indicate a slow equilibrium of association and dissociation and are consistent with slow binding of the inhibitors. In contrast, for viruses with decreased susceptibility, preincubation had minimal effect on the IC50s, consistent with fast binding. Therefore this modified assay provides additional phenotypic information about the rate of inhibitor binding in addition to the IC50, and critically demonstrates the differential effect of incubation times on the IC50 and Ki values of wild type and mutant viruses for each of the inhibitors

Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end

Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end