A theoretical analysis of the free vibration of discretely stiffened cylindrical shells with arbitrary end conditions

Theoretical analysis of free vibration of discretely stiffened cylindrical shells with arbitrary end condition

Magnetic states of linear defects in graphene monolayers: effects of strain and interaction

The combined effects of defect-defect interaction and of uniaxial or biaxial strains of up to 10\% on the development of magnetic states on the defect-core-localized quasi-one-dimensional electronic states generated by the so-called 558 linear extended defect in graphene monolayers are investigated by means of {\it ab initio} calculations. Results are analyzed on the basis of the heuristics of the Stoner criterion. We find that conditions for the emergence of magnetic states on the 558 defect can be tuned by uniaxial tensile parallel strains (along the defect direction) at both limits of isolated and interacting 558 defects. Parallel strains are shown to lead to two cooperative effects that favor the emergence of itinerant magnetism: enhancement of the DOS of the resonant defect states in the region of the Fermi level and tuning of the Fermi level to the maximum of the related DOS peak. A perpendicular strain is likewise shown to enhance the DOS of the defect states, but it also effects a detunig of the Fermi level that shifts away from the maximum of the DOS of the defect states, which inhibts the emergence of magnetic states. As a result, under biaxial strains the stabilization of a magnetic state depends on the relative magnitudes of the two components of strain.Comment: 9 pages 8 figure

Integrating Livestock and Cropping Systems: Interseeding Cereal Rye into Corn for Late Season Grazing

Corn (Zea mays) grown for grain is harvested too late in the year in many temperate regions to establish a cover crop to provide winter ground cover and an opportunity for late season grazing. The objective of this project is to evaluate the effect of interseeding cereal rye (Secale cereale) into corn for use as grazed forage after corn grain harvest on corn grain yield and additional grazing day/ha. In a 4-year study, corn was planted (64,246 plants/ha) in spring on two, 4.8-ha fields in central Pennsylvania. Cereal rye was interseeded (135 kg/ha) into the corn at the V4-V6 stage. Corn was harvested as grain in November and each field was divided into six, 0.8-ha paddocks and randomly assigned to either grazed (GRAZ) or ungrazed (NG) treatments. Beef cattle frontal-grazed three of the paddocks (four cows/paddock) in each field approximately four to five weeks after corn grain harvest and, if growth allowed, again in early spring before subsequent corn planting. Corn fodder (after grain harvest), corn grain and cereal rye yields were monitored each fall. Cereal rye growth was also monitored in early spring. On average, the cereal rye (plus the corn stover) provided enough forage for an additional 115-130 grazing days/ha in the fall. While early spring growth has the potential to provide even greater forage yields than fall, growth is much less dependable than fall. Corn grain yields did not decrease as a result of grazing, or of repeated plantings of corn year to year, ranging from 9,516-10,088 kg/ha across GRAZ and NG paddocks except in 2019 (dry year) when corn grain yields averaged 6,053 kg/ha across both GRAZ and NG treatments

Species Richness, Species Identity and Ecosystem Function in Managed Temperate Grasslands

Manipulation of plant species diversity may provide a way to improve the ecosystem functioning of managed systems by increasing productivity and suppressing weedy species. As yet, the functional role of species richness is not well-enough understood to enable practical application. We investigated the effects of differing species richness on community stability and invasion resistance in a grazed temperate grassland

Brix as an Indicator of Sugar Content and Nutritive Value in Alfalfa and Orchardgrass Herbage

Brix, a measurement of total dissolved solids in solution, has been used by forage producers to provide real-time estimates of energy content of fresh herbage. However, its efficacy has never been validated in herbage through wet chemistry testing and comparisons with other nutritive value parameters. This study compared and correlated Brix measurements with sugar concentrations and common nutritive value parameters relating to protein, fiber, and energy to determine the viability of using Brix to predict when to graze or harvest fresh herbage. Brix measurements were collected monthly on fresh herbage samples of alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) from May to August in 2019 and 2021. Herbage was immediately flash frozen with liquid nitrogen and analyzed for sugar concentration and nutritive value. Brix did not differ among sampling dates for alfalfa and only differed at the May sampling for orchardgrass, indicating that Brix values were not affected by harvest date during late spring and summer months. When correlated across all sampling dates, Brix was positively correlated to sugar concentrations, reduced fiber, and greater net energy concentrations in alfalfa, but not positively correlated to any nutritive value parameters in orchardgrass. These results indicated that Brix should be used only in a limited fashion to predict energy content of fresh herbage and is more reliable when used with legumes than grasses

Intake and Milk Production of Lactating Dairy Cows Grazing Diverse Forage Mixtures Over Two Grazing Seasons

Voluntary intake and stocking rate are key determinants of animal performance on pasture. Greater plant diversity in grassland plant communities has been linked to increased primary production, greater stability in response to disturbance, and reduced weed pressure. Thus, increasing plant diversity may be one approach to improving animal productivity. An experiment was conducted to determine the effects of forage diversity on intake and milk production of lactating dairy cows over two grazing seasons

Managing Interspecies Competition to Improve Spring Pasture

Orchardgrass (Dactylis glomerata L.) is one of the earliest maturing pasture grasses utilized in the northeastern United States. However, wet springs can delay forage harvesting resulting in advanced forage maturity and reduction in nutritive value. Chicory (Cichorium intybus L.) is a tall, upright-growing forb that shows promise as a high-energy companion crop to orchardgrass and may delay orchardgrass maturity through shading effects on plant morphology. The objective of this study was to evaluate monocultures and mixtures of orchardgrass, chicory, and white clover (Trifolium repens L.) over two consecutive springs to determine the effects of species diversity on plant maturity, nutritive characteristics, and botanical composition of forage mass. Forage monocultures and mixtures were planted in central Pennsylvania in August 2018 and were observed for two years with three harvests occurring each year (one each in spring, summer, and fall). In the first spring, orchardgrass demonstrated nine days delay in maturity when grown with chicory as compared to when grown in monocultures or in orchardgrass-white clover mixtures. Although orchardgrass was at an earlier developmental stage, fiber concentrations were similar when grown with or without chicory. Additionally, in the first spring, orchardgrass mixtures containing chicory had 1.5x greater forage mass than orchardgrass monocultures and orchardgrass-white clover mixtures. Chicory biomass was low in the second spring, likely due to winterkill following a late fall harvest the previous year, resulting in a negligible effect on orchardgrass. However, orchardgrass-chicory-white clover mixtures (even with low amounts of chicory in the second year) had the greatest forage mass and nutritive value yield over both years, indicating that these mixtures can provide greater agronomic benefits than orchardgrass monocultures

Diverse Forage Mixtures Effect on Herbage Yield, Sward Composition, and Dairy Cattle Performance

Managing complex mixtures of plants to take advantage of spatial and temporal variability in land and climate may be one ecological approach to increase productivity of pastures. We tested the hypothesis that complex mixtures of forage species would yield more herbage and reduce weed competition compared with a simple grass-legume mixture in grazed pastures

Capacity Value of Wind Power

Power systems are planned such that they have adequate generation capacity to meet the load, according to a defined reliability target. The increase in the penetration of wind generation in recent years has led to a number of challenges for the planning and operation of power systems. A key metric for generation system adequacy is the capacity value of generation. The capacity value of a generator is the contribution that a given generator makes to generation system adequacy. The variable and stochastic nature of wind sets it apart from conventional energy sources. As a result, the modeling of wind generation in the same manner as conventional generation for capacity value calculations is inappropriate. In this paper a preferred method for calculation of the capacity value of wind is described and a discussion of the pertinent issues surrounding it is given. Approximate methods for the calculation are also described with their limitations highlighted. The outcome of recent wind capacity value analyses in Europe and North America, along with some new analysis, are highlighted with a discussion of relevant issues also given

Telomerase activity in human leukemic cells with or without monosomy 7 or 7q-

BACKGROUND: In bone marrow material from patients with various leukemias we noted that samples with either a deletion on the long arm of one chromosome 7 (7q-) or a monosomy 7 had a higher telomerase activity. Considering that introduction of a chromosome 7 into a cancer cell line had been reported to eliminate telomerase activity, that 7q- is a common negative prognostic finding in cancers, and that the deleted segment (band 7q31) contains an unidentified tumor suppressor gene, we wondered if this gene might be a telomerase inhibitor. RESULTS: We found no significant difference in telomerase activity between the three groups of patient samples. In contrast to reports on tumor cell lines we observed no amplification of the telomerase genes. METHODS: We analyzed telomerase activity and copy number of the telomerase genes hTERT and hTR in frozen archival bone marrow samples from leukemia patients with a referral diagnosis of AML, and either a monosomy for chromosome 7, a deletion on the long arm of chromosome 7 (7q-), or none of these aberrations. Telomerase activity was measured with a commercially available kit, and the copy number of the telomerase genes was tested by FISH. CONCLUSIONS: We found no evidence of a telomerase inhibitor in band 7q31. The lack of telomerase gene amplification found in cell lines from solid tumors could reflect that this amplification is a property of solid tumors, not of hematological cancers