SEARCH · Engineering Papers
Results for “conservation”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Soil carbon change in intensive agriculture after 25 years of conservation management
Changes in soil organic carbon (SOC) and nitrogen (SON) are strongly affected by land management but few long-term comparative studies have surveyed changes throughout the whole soil profile. We quantified 25-year SOC and SON changes to 1 m in 10 replicate ecosystems at an Upper Midwest, USA site. We compared four annual cropping systems in maize (Zea mays)-soybean (Glycine max)-winter wheat (Triticum aestivum) rotations, each managed differently (Conventional, No-till, Reduced input, and Biologically based); in three managed perennial systems (hybrid Poplar (Populus × euramericana), Alfalfa (Medicago sativa), and Conifer (Pinus spp.); and in three successional systems (Early, Mid- and Late succession undergoing a gradual change in species composition and structure over time). Both Reduced input and Biologically based systems included winter cover crops. Neither SOC nor SON changed significantly in the Conventional or Late successional systems over 25 years. All other systems gained SOC and SON to different degrees. SOC accrual was fastest in the Early successional system (0.8 ± 0.1 Mg C ha –1 y –1 ) followed by Alfalfa and Conifer (avg. 0.7 ± 0.1 Mg C ha –1 y –1 ), Poplar, Reduced input, and Biologically based systems (avg. 0.4 ± 0.1 Mg C ha –1 y –1 ), and Mid-successional and No-till systems (0.3 and 0.2 Mg C ha –1 y –1 , respectively). Over the most recent 12 years, rates of SOC accrual slowed in all systems except Reduced input and Mid-successional. There was no evidence of SOC loss at depth in any system, including No-till. Rates of SON accrual ranged from 64.7 to 0.8 kg N ha –1 y –1 in the order Alfalfa ≥ Early successional > Reduced input and Biologically based ≥ Poplar > No-till and Conifer > Mid-successional systems. Pyrogenic C levels in the Conventional, Early, and Late successional systems were similar despite 17 years of annual burning in the Early successional system (~ 15 % of SOC to 50 cm, on average, and ~40 % of SOC from 50 to 100 cm). Results underscore the importance of cover crops, perennial crops, and no-till options for sequestering whole profile C in intensively managed croplands.
Breast Tangent Beam Energy, Surgical Bed-to-Skin Distance and Local Recurrence After Breast-Conserving Treatment
Higher energy (>6 MV) photons reduce dose inhomogeneity with breast tangent beams, thereby reducing late breast toxicity, but skin and superficial tissue sparing by higher energy beams raises concerns about local recurrence (LR) risk. This study aimed to determine whether beam energy and surgical bed-to-skin distance affect LR.
Members of the vertebrate contactin and amyloid precursor protein families interact through a conser
Explore the source record for details and available documents.
Type II BMP and activin receptors BMPR2 and ACVR2A share a conserved mode of growth factor recogniti
Explore the source record for details and available documents.
Discovery and structural characterization of the D-box, a conserved TonB motif that couples an inner-membrane motor to outer-membrane transport
Not Available
Identification of a conserved α-helical domain at the N terminus of human DNA methyltransferase 1
Not Available
Mutation-induced shift of the photosystem II active site reveals insight into conserved water channels
Not Available
Conserved and repetitive motifs in an intrinsically disordered protein drive ⍺-carboxysome assembly
Not Available
The redox landscape of pyruvate:ferredoxin oxidoreductases reveals often conserved Fe–S cluster potentials
Not provided.
Conservative high-order discontinuous Galerkin remap scheme on curvilinear polyhedral meshes
Not Available
Adaptive total variation stable local timestepping for conservation laws
Not Available
A consistent and conservative Phase-Field method for compressible multiphase flows with shocks
Not Available
Denoising Particle-In-Cell data via Smoothness-Increasing Accuracy-Conserving filters with application to Bohm speed computation
Not Available
A consistent and conservative phase-field method for compressible N-phase flows: Consistent limiter and multiphase reduction-consistent formulation
Not Available
An implicit, conservative electrostatic particle-in-cell algorithm for paraxial magnetic nozzles
Not Available