Research Progress Report, No. 17

Legumes are notable for their ability to convert atmospheric dinitrogen into forms of nitrogen which are usable by plants. This is done in association with bacteria (called Rhizobium) which inhabit nodules of the plant roots. This process is called nitrogen-fixation. Legumes are important as forage and food crops due to their high protein content. Some are also useful for soil conservation purposes. There was no information on nitrogen fixation by legume crops in Alaska. This research was initiated to determine how much nitrogen different types of legumes can fix in interior Alaska

Government Policy Influence on Land Use and Land Cover Changes: A 30-Year Analysis

This study investigated land use and land cover (LULC) patterns and changes in the Bandon Bay area of Thailand from 1991 to 2021 using satellite imagery, the first comprehensive effort to assess historical LULC trends over the past 30 years and forecast future LULC scenarios using the CA-Markov model for 2031, 2041, and 2051. Results showed the predominant LULC during 1991-2001 was the abandoned paddy fields, and during 2006-2021 was the oil palm plantations. During 1991-2001, the abandoned paddy fields changed significantly, with a net gain of 59.28 km2. From 2001-2011 and 2011-2021, the oil palm plantations experienced the most crucial change, with a net gain of 292.94 km2 and 70.06 km2. In 2031, 2041, and 2051, the LULC was predicted to be oil palms, shrimp farms, mangroves, and urban and built-up lands. The LULC changes were consistent with the government policies implemented and indicated government policy as a driving force in LULC dynamics on Bandon Bay area forestry, aquaculture, and agriculture, particularly on oil palm cultivation. Government management and regulation on land use is crucial for reducing the expansion of agricultural areas, especially oil palm plantations and aquaculture areas, to mitigate negative impacts on the Bandon Bay ecosystem. Doi: 10.28991/ESJ-2024-08-05-06 Full Text: PD

Response of Microorganisms to Hot Crude Oil Spills on a Subarctic Taiga Soil

This study was conducted on the short-term effects of seasonal spills of hot Prudhoe Bay crude oil on microorganisms in a taiga soil in interior Alaska. Following a winter spill, the filamentous fungal populations were inhibited whereas the heterotrophic bacterial populations were stimulated. After a summer spill there was an initial depression of both the filamentous fungal and bacterial populations followed by a general enhancement. In both oil spill plots, yeasts; along with the denitrifying, proteolytic, oil-utilizing, and cellulose-utilizing microorganisms; were favorably affected by the oil. Soil respiration was also enhanced in the oiled plots. An extended period of study is required to fully evaluate the impact of oil on the soil microflora and the role of these microorganisms in recovery of oil-inundated areas in subarctic ecosystems

Predicting P response in Rainfed winter cereals on diverse soils using soil analysis

Phosphorus (P) fertilizers are commonly applied to agricultural soils for winter cereal production, and they represent a significant proportion of the variable costs of crop production. Many areas now have high plant-­‐ available soil P levels and regular application of P fertilizers is no longer required to achieve profitable yields (Sims and Vadas 2005). However, in all cases, soil testing can provide key information for improved decision making about P management. Recently in Australia, a national database (the Better Fertilizer Decisions for Crops (BFDC) National Database) of nutrient response trials for grain crops has been assembled (Watmuff et al. 2013). The treatment series entered were subject to rigorous checks to ensure they were valid for re-­‐analysis in the database. The database represents a valuable resource with which to assess response of winter cereals to P across a wide range of cropping eras (modern vs earlier periods), soil types, seasonal conditions, sampling depths, soil test methods and species. The objective of this study was to examine factors affecting critical soil P test concentrations and confidence intervals for wheat and barley grown in Australian soils by interrogating validated data held in the BFDC National Database. Most emphasis was placed on the Colwell extractant for soil P (Colwell 1963) since it was the most widely used test and the one for which the largest and most comprehensive dataset existed

Current Challenges in Autonomous Vehicle Development

The field of autonomous vehicles is a rapidly growing one, with significant interest from both government and industry sectors. Autonomous vehicles represent the intersection of artificial intelligence (AI) and robotics, combining decision-making with real-time control. Autonomous vehicles are desired for use in search and rescue, urban reconnaissance, mine detonation, supply convoys, and more. The general adage is to use robots for anything dull, dirty, dangerous or dumb. While a great deal of research has been done on autonomous systems, there are only a handful of fielded examples incorporating machine autonomy beyond the level of teleoperation, especially in outdoor/complex environments. In an attempt to assess and understand the current state of the art in autonomous vehicle development, a few areas where unsolved problems remain became clear. This paper outlines those areas and provides suggestions for the focus of science and technology research. The first step in evaluating the current state of autonomous vehicle development was to develop a definition of autonomy. A number of autonomy level classification systems were reviewed. The resulting working definitions and classification schemes used by the authors are summarized in the opening sections of the paper. The remainder of the report discusses current approaches and challenges in decision-making and real-time control for autonomous vehicles. Suggested research focus areas for near-, mid-, and long-term development are also presented

Photonic Quantum Logic with Narrowband Light from Single Atoms

Increasing control of single photons enables new applications of photonic quantum-enhanced technology and further experimental exploration of fundamental quantum phenomena. Here, we demonstrate quantum logic using narrow linewidth photons that are produced under nearly perfect quantum control from a single ^87Rb atom strongly coupled to a high-finesse cavity. We use a controlled- NOT gate integrated into a photonic chip to entangle these photons, and we observe non-classical correlations between events separated by periods exceeding the travel time across the chip by three orders of magnitude. This enables quantum technology that will use the properties of both narrowband single photon sources and integrated quantum photonics, such as networked quantum computing, narrow linewidth quantum enhanced sensing and atomic memories.Comment: 5 pates, 3 figure

Evapotranspiration in Northern Agro-Ecosystems: Numerical Simulation and Experimental Comparison

Evapotranspiration and near-surface soil moisture dynamics are key-entangled variables regulating flux at the surface-atmosphere interface. Both are central in improving mass and energy balances in agro ecosystems. However, under the extreme conditions of high-latitude soils and weather pattern variability, the implementation of such coupled liquid and vapor phase numerical simulation remain to be tested. We consider the nonisothermal solution of the vapor flux equation that accounts for the thermally driven water vapor transport and phase changes. Fully coupled flux model outputs are compared and contrasted against field measurements of soil temperature, heat flux, water content, and evaporation in a subarctic agroecosystem in Alaska. Two well-defined hydro-meteorological situations were selected: dry and wet periods. Numerical simulation was forced by time series of incoming global solar radiation and atmospheric surface layer thermodynamic parameters: surface wind speed, ambient temperature, relative humidity, precipitation, and soil temperature and soil moisture. In this simulation, soil parameters changing in depth and time are considered as dynamically adjusted boundary conditions for solving the set of coupled differential equations. Results from this evaluation give good correlation of modeled and observed data in net radiation (Rnet) (R2 of 0.92, root mean square error (RMSE) of 45 W m−2), latent heat (0.70, RMSE of 53 W m−2), and sensible heat (R2 = 0.63, RMSE = 32 W m−2) during the dry period. On the other hand, a poor agreement was obtained in the radiative fluxes and turbulent fluxes during the wet period due to the lack of representation in the radiation field and differences in soil dynamics across the landscape