Storm impact on sea surface temperature and chlorophyll α in the Gulf of Mexico and Sargasso Sea based on daily cloud-free satellite data reconstructions

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 43 (2016): 12,199–12,207, doi:10.1002/2016GL071178.Upper ocean responses to tropical storms/hurricanes have been extensively studied using satellite observations. However, resolving concurrent sea surface temperature (SST) and chlorophyll α (chl α) responses along storm tracks remains a major challenge due to extensive cloud coverage in satellite images. Here we produce daily cloud-free SST and chl α reconstructions based on the Data INterpolating Empirical Orthogonal Function method over a 10 year period (2003–2012) for the Gulf of Mexico and Sargasso Sea regions. Daily reconstructions allow us to characterize and contrast previously obscured subweekly SST and chl α responses to storms in the two main storm-impacted regions of the Atlantic Ocean. Statistical analyses of daily SST and chl α responses revealed regional differences in the response time as well as the response sensitivity to maximum sustained wind speed and translation speed. This study demonstrates that SST and chl α responses clearly depend on regional ocean conditions and are not as universal as might have been previously suggested.Gulf of Mexico Research Initiative/GISR Grant Number: 02-S130202; NOAA Grant Number: NA11NOS0120033; NASA Grant Numbers: NNX12AP84G, NNX13AD80G2017-06-1

Carbon Free Energy Development and the Role of Small Modular Reactors: A Review and Decision Framework for Deployment in Developing Countries

Global energy demand is projected to continue to grow over the next two decades, especially in developing economies. An emerging energy technology with distinct advantages for growing economies is small modular nuclear reactors (SMRs). Their smaller size makes them suitable for areas with limited grid capacities and dispersed populations while enabling flexibility in generating capacity and fuel sources. They have the ability to pair well with renewable energy sources, the major source of increased energy capacity for many developing economies. Further advantages include their passive safety features, lower capital requirements, and reduced construction times. As a result, SMRs have potential for overcoming energy poverty issues for growing economies without increasing carbon emissions. This study reviews the features and viability of SMRs to meet increasing energy capacity needs and develops a decision support framework to evaluate the market conditions for SMR deployment to emerging economies. The focus is on identifying countries best suited for domestic deployment of SMRs rather than vendor countries with ongoing or future SMR development programs for export. We begin by examining the characteristics of over two hundred countries and identifying those that satisfy several necessary economic, electrical grid capacity, and nuclear security conditions. Countries satisfying these necessary conditions are then evaluated using the Analytical Hierarchy Process (AHP) using criteria related to the economic and financial conditions, infrastructure and technological framework, and governmental policies within each country. The results find that countries with increasing GDP and energy demand that possess a robust infrastructure, energy production from high GHG sources, and governmental policies favorable to foreign investment are well-suited for future SMR deployment

Dynamic Complexity Study of Nuclear Reactor and Process Heat Application Integration

Abstract This paper describes the key obstacles and challenges facing the integration of nuclear reactors with process heat applications as they relate to dynamic issues. The paper also presents capabilities of current modeling and analysis tools available to investigate these issues. A pragmatic approach to an analysis is developed with the ultimate objective of improving the viability of nuclear energy as a heat source for process industries. The extension of nuclear energy to process heat industries would improve energy security and aid in reduction of carbon emissions by reducing demands for foreign derived fossil fuels. The paper begins with an overview of nuclear reactors and process application for potential use in an integrated system. Reactors are evaluated against specific characteristics that determine their compatibility with process applications such as heat outlet temperature. The reactor system categories include light water, heavy water, small to medium, near term high-temperature, and far term high temperature reactors. Low temperature process systems include desalination, district heating, and tar sands and shale oil recovery. High temperature processes that support hydrogen production include steam reforming, steam cracking, hydrogen production by electrolysis, and far-term applications such as the sulfur iodine chemical process and high-temperature electrolysis. A simple static matching between complementary systems is performed; however, to gain a true appreciation for system integration complexity, time dependent dynamic analysis is required. The paper identifies critical issues arising from dynamic complexity associated with integration of systems. Operational issues include scheduling conflicts and resource allocation for heat and electricity. Additionally, economic and safety considerations that could impact the successful integration of these systems are considered. Economic issues include the cost differential arising due to an integrated system and the economic allocation of electricity and heat resources. Safety issues include changes in regulatory constraints imposed on the facilities. Modeling and analysis tools, such as System Dynamics for time dependent operational and economic issues and RELAP5 3D for chemical transient affects, are evaluated. The results of this study advance the body of knowledge toward integration of nuclear reactors and process heat applications

A VISION of Advanced Nuclear System Cost Uncertainty

VISION (VerifIable fuel cycle SImulatiON) is the Advanced Fuel Cycle Initiative’s and Global Nuclear Energy Partnership Program’s nuclear fuel cycle systems code designed to simulate the US commercial reactor fleet. The code is a dynamic stock and flow model that tracks the mass of materials at the isotopic level through the entire nuclear fuel cycle. As VISION is run, it calculates the decay of 70 isotopes including uranium, plutonium, minor actinides, and fission products. VISION.ECON is a sub-model of VISION that was developed to estimate fuel cycle and reactor costs. The sub-model uses the mass flows generated by VISION for each of the fuel cycle functions (referred to as modules) and calculates the annual cost based on cost distributions provided by the Advanced Fuel Cycle Cost Basis Report1. Costs are aggregated for each fuel cycle module, and the modules are aggregated into front end, back end, recycling, reactor, and total fuel cycle costs. The software also has the capability to perform system sensitivity analysis. This capability may be used to analyze the impacts on costs due to system uncertainty effects. This paper will provide a preliminary evaluation of the cost uncertainty affects attributable to 1) key reactor and fuel cycle system parameters and 2) scheduling variations. The evaluation will focus on the uncertainty on the total cost of electricity and fuel cycle costs. First, a single light water reactor (LWR) using mixed oxide fuel is examined to ascertain the effects of simple parameter changes. Three system parameters; burnup, capacity factor and reactor power are varied from nominal cost values and the affect on the total cost of electricity is measured. These simple parameter changes are measured in more complex scenarios 2-tier systems including LWRs with mixed fuel and fast recycling reactors using transuranic fuel. Other system parameters are evaluated and results will be presented in the paper. Secondly, the uncertainty due to variation in scheduling effects is evaluated. For example, economic impacts due to increased nuclear energy growth rates and speed-ups in deployment of fuel cycle facilities and fast reactors. Preliminary results show that significant variations in the costs of the scenarios can result from variations in burnup, capacity factor and reactor power. The paper will include new results from analysis of additional system variables and due to scheduling dynamics. Reference 1. Shropshire, D.E. et al, 2007, Advanced Fuel Cycle Cost Basis, INL/EXT-07-12107, April 2007

Examining Differences Between Asian Americans and Whites for Gambling and Drinking

Limited research have examined the ethnic differences in gambling and drinking among emerging adults, therefore; little is known about what is placing Asian American at-risk for involvement with these behaviors. The purpose of this study was to examine ethnic differences in risk factors between Asian Americans and White Americans for gambling and drinking at the two levels of involvement: abstinence and problems. The main objective 1) if there are ethnic differences among emerging adults in gambling and drinking involvement, 2) why these differences exist, and 3) which impulsivity and psychological distress variables are specific to each of these ethnic groups. The sample consisted of college students, A total of 823 participants, 414 (50.3%) females and 409 (49.7%) males, with an age range of 18-36 from the psychology subject pool of a large West Coast university were selected for this study. The sample was composed of 464 (56.4%) Asian Americans and 359 (43.6%) White Americans. White Americans were found to abstain less and develop more problems associated with drinking. No ethnic differences were found for gambling abstinence. Asian Americans were developing more problems gambling compared to White Americans. Ethnic differences were also found through risk-factors at each level of involvement with Asian Americans being highly correlated to psychological distress risk-factors and White Americans impulsivity factors. Of these risk factors, depression and belief in good luck (BIGL) mediated for problem gambling and social anxiety mediated for drinking abstinence. Overall, results indicated an increase need for more culturally sensitive and comprehensive based treatment and prevention programs

Influence of food quality on larval growth of Atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Mexico

Larval abundances of Atlantic bluefin tuna (ABT) in the Gulf of Mexico are currently utilized to inform future recruitment by providing a proxy for the spawning potential of western ABT stock. Inclusion of interannual variations in larval growth is a key advance needed to translate larval abundance to recruitment success. However, little is known about the drivers of growth variations during the first weeks of life. We sampled patches of western ABT larvae in 3–4 day Lagrangian experiments in May 2017 and 2018, and assessed age and growth rates from sagittal otoliths relative to size categories of zooplankton biomass and larval feeding behaviors from stomach contents. Growth rates were similar, on average, between patches (0.37 versus 0.39 mm d−1) but differed significantly through ontogeny and were correlated with a food limitation index, highlighting the importance of prey availability. Otolith increment widths were larger for postflexion stages in 2018, coincident with high feeding on preferred prey (mainly cladocerans) and presumably higher biomass of more favorable prey type. Faster growth reflected in the otolith microstructures may improve survival during the highly vulnerable larval stages of ABT, with direct implications for recruitment processes.En prensa1,74

Bluefin Tuna Larvae in Oligotrophic Ocean Foodwebs, Investigations of Nutrients to Zooplankton: Overview of the BLOOFINZ-Gulf of Mexico program

Western Atlantic bluefin tuna (ABT) undertake long-distance migrations from rich feeding grounds in the North Atlantic to spawn in oligotrophic waters of the Gulf of Mexico (GoM). Stock recruitment is strongly affected by interannual variability in the physical features associated with ABT larvae, but the nutrient sources and food-web structure of preferred habitat, the edges of anticyclonic loop eddies, are unknown. Here, we describe the goals, physical context, design and major findings of an end-to-end process study conducted during peak ABT spawning in May 2017 and 2018. Mesoscale features in the oceanic GoM were surveyed for larvae, and five multi-day Lagrangian experiments measured hydrography and nutrients; plankton biomass and composition from bacteria to zooplankton and fish larvae; phytoplankton nutrient uptake, productivity and taxon-specific growth rates; micro- and mesozooplankton grazing; particle export; and ABT larval feeding and growth rates. We provide a general introduction to the BLOOFINZ-GoM project (Bluefin tuna Larvae in Oligotrophic Ocean Foodwebs, Investigation of Nitrogen to Zooplankton) and highlight the finding, based on backtracking of experimental waters to their positions weeks earlier, that lateral transport from the continental slope region may be more of a key determinant of available habitat utilized by larvae than eddy edges per se.Postprint1,74

Trade-Offs Between Risks of Predation and Starvation In Larvae Make the Shelf Break an Optimal Spawning Location For Atlantic Bluefin Tuna

Atlantic bluefin tuna (ABT) (Thunnus thynnus) travel long distances to spawn in oligotrophic regions of the Gulf of Mexico (GoM) which suggests these regions offer some unique benefit to offspring survival. To better understand how larval survival varies within the GoM a spatially explicit, Lagrangian, individual-based model was developed that simulates dispersal and mortality of ABT early life stages within realistic predator and prey fields during the spawning periods from 1993 to 2012. The model estimates that starvation is the largest cumulative source of mortality associated with an early critical period. However, elevated predation on older larvae is identified as the main factor limiting survival to late postflexion. As a result, first-feeding larvae have higher survival on the shelf where food is abundant, whereas older larvae have higher survival in the open ocean with fewer predators, making the shelf break an optimal spawning area. The modeling framework developed in this study explicitly simulates both physical and biological factors that impact larval survival and hence could be used to support ecosystem based management efforts for ABT under current and future climate conditions

Synthesis Paper: Targeted Livestock Grazing: Prescription for Healthy Rangelands

Targeted livestock grazing is a proven tool for manipulating rangeland vegetation, and current knowledge about targeted livestock grazing is extensive and expanding rapidly. Targeted grazing prescriptions optimize the timing, frequency, intensity, and selectivity of grazing (or browsing) in combinations that purposely exert grazing/browsing pressure on specific plant species or portions of the landscape. Targeted grazing differs from traditional grazing management in that the goal of targeted grazing is to apply defoliation or trampling to achieve specific vegetation management objectives, whereas the goal of traditional livestock grazing management is generally the production of livestock commodities. A shared aim of targeted livestock grazing and traditional grazing management is to sustain healthy soils, flora, fauna, and water resources that, in turn, can sustain natural ecological processes (e.g., nutrient cycle, water cycle, energy flow). Targeted grazing prescriptions integrate knowledge of plant ecology, livestock nutrition, and livestock foraging behavior. Livestock can be focused on target areas through fencing, herding, or supplement placement. Although practices can be developed to minimize the impact of toxins contained in target plants, the welfare of the animals used in targeted grazing must be a priority. Monitoring is needed to determine if targeted grazing is successful and to refine techniques to improve efficacy and efficiency. Examples of previous research studies and approaches are presented to highlight the ecological benefits that can be achieved when targeted grazing is applied properly. These cases include ways to suppress invasive plants and ways to enhance wildlife habitat and biodiversity. Future research should address the potential to select more adapted and effective livestock for targeted grazing and the associated animal welfare concerns with this practice. Targeted livestock grazing provides land managers a viable alternative to mechanical, chemical, and prescribed fire treatments to manipulate rangeland vegetation

Disentangling a Holobiont – Recent Advances and Perspectives in Nasonia Wasps

The parasitoid wasp genus Nasonia (Hymenoptera: Chalcidoidea) is a well-established model organism for insect development, evolutionary genetics, speciation, and symbiosis. The host-microbiota assemblage which constitutes the Nasonia holobiont (a host together with all of its associated microbes) consists of viruses, two heritable bacterial symbionts and a bacterial community dominated in abundance by a few taxa in the gut. In the wild, all four Nasonia species are systematically infected with the obligate intracellular bacterium Wolbachia and can additionally be co-infected with Arsenophonus nasoniae. These two reproductive parasites have different transmission modes and host manipulations (cytoplasmic incompatibility vs. male-killing, respectively). Pioneering studies on Wolbachia in Nasonia demonstrated that closely related Nasonia species harbor multiple and mutually incompatible Wolbachia strains, resulting in strong symbiont-mediated reproductive barriers that evolved early in the speciation process. Moreover, research on host-symbiont interactions and speciation has recently broadened from its historical focus on heritable symbionts to the entire microbial community. In this context, each Nasonia species hosts a distinguishable community of gut bacteria that experiences a temporal succession during host development and members of this bacterial community cause strong hybrid lethality during larval development. In this review, we present the Nasonia species complex as a model system to experimentally investigate questions regarding: (i) the impact of different microbes, including (but not limited to) heritable endosymbionts, on the extended phenotype of the holobiont, (ii) the establishment and regulation of a species-specific microbiota, (iii) the role of the microbiota in speciation, and (iv) the resilience and adaptability of the microbiota in wild populations subjected to different environmental pressures. We discuss the potential for easy microbiota manipulations in Nasonia as a promising experimental approach to address these fundamental aspects