Twelve Years of Stover Removal Increases Soil Erosion Potential without Impacting Yield

Corn (Zea mays L.) stover (non-grain aboveground biomass) in the US Corn Belt is used increasingly for livestock grazing and co-feed and for cellulosic bioenergy production. Continuous stover removal, however, could alter long-term agricultural productivity by affecting soil organic C (SOC) and soil physical properties, indicators of soil fertility and erosion potential. In this study, we showed that 12 consecutive yr of 55% stover removal did not affect mean grain yields at any N fertilizer rate (4.5, 6.3, and 6.0 Mg ha−1 for 60, 120, and 180 kg N ha−1 yr−1, respectively) in a marginally productive, rainfed continuous corn system under no-till (NT). Although SOC increased in the top 30 cm of all soils since 1998 (0.54–0.79 Mg C ha−1 yr−1), stover removal tended to limit SOC gains compared with no removal. Near-surface soils (0–5-cm depth) were more sensitive to stover removal and showed a 41% decrease in particulate organic matter stocks, smaller mean weight diameter of dry soil aggregates, and lower abundance of water-stable soil aggregates compared with soils with no stover removal. Increasing N fertilizer rate mitigated losses in total water-stable aggregates in near-surface soils related to stover removal. Collectively, however, our results indicated soil structure losses in surface soils due to lower C inputs. Despite no effect on crop yields and overall SOC gains with time using NT management, annually removing stover for 12 yr resulted in a higher risk of wind and water erosion at this NT continuous corn site in the western Corn Belt

DEVELOPMENT AND APPLICATION OF MATERIALS PROPERTIES FOR FLAW STABILITY ANALYSIS IN EXTREME ENVIRONMENT SERVICE

Discovery of aging phenomena in the materials of a structure may arise after its design and construction that impact its structural integrity. This condition can be addressed through a demonstration of integrity with the material-specific degraded conditions. Two case studies of development of fracture and crack growth property data, and their application in development of in-service inspection programs for nuclear structures in the defense complex are presented. The first case study covers the development of fracture toughness properties in the form of J-R curves for rolled plate Type 304 stainless steel with Type 308 stainless steel filler in the application to demonstrate the integrity of the reactor tanks of the heavy water production reactors at the Savannah River Site. The fracture properties for the base, weld, and heat-affected zone of the weldments irradiated at low temperatures (110-150 C) up to 6.4 dpa{sub NRT} and 275 appm helium were developed. An expert group provided consensus for application of the irradiated properties for material input to acceptance criteria for ultrasonic examination of the reactor tanks. Dr. Spencer H. Bush played a lead advisory role in this work. The second case study covers the development of fracture toughness for A285 carbon steel in high level radioactive waste tanks. The approach in this case study incorporated a statistical experimental design for material testing to address metallurgical factors important to fracture toughness. Tolerance intervals were constructed to identify the lower bound fracture toughness for material input to flaw disposition through acceptance by analysis

Combining best evidence: A novel method to calculate the alcohol-attributable fraction and its variance for injury mortality

<p>Abstract</p> <p>Background</p> <p>The alcohol-attributable fraction for injury mortality is defined as the proportion of fatal injury that would disappear if consumption went to zero. Estimating this fraction has previously been based on a simplistic view of drinking and associated risk. This paper develops a new way to calculate the alcohol-attributable fraction for injury based on different dimensions of drinking, mortality data, experimental data, survey research, new risk scenarios, and by incorporating different distributions of consumption within populations. For this analysis, the Canadian population in 2005 was used as the reference population.</p> <p>Methods</p> <p>Binge drinking and average daily consumption were modeled separately with respect to the calculation of the AAF. The acute consumption risk was calculated with a probability-based method that accounted for both the number of binge drinking occasions and the amount of alcohol consumed per occasion. The average daily consumption was computed based on the prevalence of daily drinking at various levels. These were both combined to get an overall estimate. 3 sensitivity analyses were performed using different alcohol consumption parameters to test the robustness of the model. Calculation of the variance to generate confidence limits around the point estimates was accomplished via Monte Carlo resampling methods on randomly generated AAFs that were based on the distribution and prevalence of drinking in the Canadian population.</p> <p>Results</p> <p>Overall, the AAFs decrease with age and are significantly lower for women than men across all ages. As binge drinking increases, the injury mortality AAF also increases. Motor vehicle collisions show the largest relative increases in AAF as alcohol consumption is increased, with over a 100% increase in AAF from the lowest to highest consumption category. Among non-motor vehicle collisions, the largest change in total AAF occurred both for homicide and other intentional injuries at about a 15% increase in the AAF from the lowest to the highest binge consumption scenarios.</p> <p>Conclusions</p> <p>This method combines the best available evidence to generate new alcohol-attributable fractions for alcohol-attributable injury mortality. Future research is needed to refine the risk function for non-motor vehicle injury types and to investigate potential interactions between binge drinking and average volume of alcohol consumption.</p

Prime movers : mechanochemistry of mitotic kinesins

Mitotic spindles are self-organizing protein machines that harness teams of multiple force generators to drive chromosome segregation. Kinesins are key members of these force-generating teams. Different kinesins walk directionally along dynamic microtubules, anchor, crosslink, align and sort microtubules into polarized bundles, and influence microtubule dynamics by interacting with microtubule tips. The mechanochemical mechanisms of these kinesins are specialized to enable each type to make a specific contribution to spindle self-organization and chromosome segregation

Inhibition of breathing after surfactant depletion is achieved at a higher arterial PCO(2 )during ventilation with liquid than with gas

BACKGROUND: Inhibition of phrenic nerve activity (PNA) can be achieved when alveolar ventilation is adequate and when stretching of lung tissue stimulates mechanoreceptors to inhibit inspiratory activity. During mechanical ventilation under different lung conditions, inhibition of PNA can provide a physiological setting at which ventilatory parameters can be compared and related to arterial blood gases and pH. OBJECTIVE: To study lung mechanics and gas exchange at inhibition of PNA during controlled gas ventilation (GV) and during partial liquid ventilation (PLV) before and after lung lavage. METHODS: Nine anaesthetised, mechanically ventilated young cats (age 3.8 ± 0.5 months, weight 2.3 ± 0.1 kg) (mean ± SD) were studied with stepwise increases in peak inspiratory pressure (PIP) until total inhibition of PNA was attained before lavage (with GV) and after lavage (GV and PLV). Tidal volume (V(t)), PIP, oesophageal pressure and arterial blood gases were measured at inhibition of PNA. One way repeated measures analysis of variance and Student Newman Keuls-tests were used for statistical analysis. RESULTS: During GV, inhibition of PNA occurred at lower PIP, transpulmonary pressure (Ptp) and Vt before than after lung lavage. After lavage, inhibition of inspiratory activity was achieved at the same PIP, Ptp and Vt during GV and PLV, but occurred at a higher PaCO(2 )during PLV. After lavage compliance at inhibition was almost the same during GV and PLV and resistance was lower during GV than during PLV. CONCLUSION: Inhibition of inspiratory activity occurs at a higher PaCO(2 )during PLV than during GV in cats with surfactant-depleted lungs. This could indicate that PLV induces better recruitment of mechanoreceptors than GV

Nitrosylation of Myoglobin and Nitrosation of Cysteine by Nitrite in a Model System Simulating Meat Curing

Demand is growing for meat products cured without the addition of sodium nitrite. Instead of the direct addition of nitrite to meat in formulation, nitrite is supplied by bacterial reduction of natural nitrate often added as vegetable juice/powder. However, the rate of nitrite formation in this process is relatively slow, and the total ingoing nitrite is typically less than in conventional curing processes. The objective of this study was to determine the impact of the rate of addition of nitrite and the amount of nitrite added on nitrosylation/nitrosation reactions in a model meat curing system. Myoglobin was preferentially nitrosylated as no decrease in sulfhydryl groups was found until maximum nitrosylmyoglobin color was achieved. The cysteine–myoglobin model retained more sulfhydryl groups than the cysteine-only model (p \u3c 0.05). The rate of nitrite addition did not alter nitrosylation/nitrosation reactions (p \u3e 0.05). These data suggest that the amount of nitrite but not the rate of addition impacts the nitrosylation/nitrosation reactions this syste