2,448 research outputs found

    Effects of upland stream nutrient restoration on Atlantic salmon populations

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    Aquatic biodiversity has experienced severe declines over past decades, with many species requiring conservation interventions in order to preserve and protect threatened populations. However, assessing whether conservation measures work effectively with the intended outcome is important when considering their implementation. One conservation target is the Atlantic salmon (Salmo salar), populations of which have declined dramatically since the 1960s. Given that many salmon die during the spawning migration, the reduction in the number of spawning adults has also led to fewer marine-derived nutrients being deposited in upland streams in the form of salmon carcasses. These carcasses fertilise the nursery streams of the salmon, to the potential benefit of the young fish, and so the decline in the number of adult salmon carcasses may have adverse effects on the next generation. In this thesis, I explore in successive chapters the potential for restoring the nutrients that are normally supplied by returning spawning salmon to upland streams, by using carcass analogue pellets. I examine the impacts of different methods of the application of these pellets, and differing doses and timing of applications, on the growth and performance of juvenile salmon populations. I also assess the effect of the application method on aquatic macroinvertebrate communities. I develop a mathematical model to predict the impact of manipulating the early freshwater growth rate of individual salmon on their life history trajectory, following a cohort of fish through to spawning and egg production; this allows exploration of the effect of nutrient additions on the viability of salmon populations. Finally, I detail an incidental study on the effects of high summer temperatures on the performance of juvenile salmon populations. Chapter 1 introduces the main issues and the study species and presents the ecological and conservation context for the study. Juvenile Atlantic salmon often reside in upland streams, and these streams may differ to the degree of nutrient limitation that they experience as a result of cultural practices leading to the oligotrophication of these streams. In Chapter 2, I review the sources, retention and fate of nutrients in upland streams, alongside reviewing the impacts of experimental nutrient additions on salmon populations. In the first experimental chapter (Chapter 3), I present the results of a twoyear experiment that compared two methods of nutrient additions using carcass analogue pellets, one via bagged pellets and the second through hand-scattered pellets. I show the differing impacts of these methods on macroinvertebrates and two cohorts of Atlantic salmon populations. The results varied between treatments and between years, but mainly demonstrated increased body size of individual invertebrates in the scattered treatment. Salmon fry (fish in their first summer of growth) in the scattered treatment showed reduced growth but greater densities, whilst fry in the bagged treatment saw no change in density and a positive effect on growth in one year of the study. There was no impact of either treatment on the body size of salmon parr (fish at least one year old). The impacts of nutrient additions are likely to vary depending on seasonal changes to environmental variables, and the amount of nutrients added is also likely to result in different impacts based on these seasonal changes. These changes are assessed in Chapter 4, where I present the results of an experiment that tested the impact of a single dose applied in early spring against a double dose applied in early spring and early summer. The single dose resulted in increased fry density but reduced growth, whilst the double dose increased both growth and density of Atlantic salmon fry. No study has assessed the impact of nutrient additions over a single generation of Atlantic salmon, and nutrient additions may have unforeseen and adverse consequences. In Chapter 5, I detail an individual-based model that aims to understand the population impact of manipulating early freshwater growth of Atlantic salmon. I demonstrate that increasing early growth results in increased numbers of fish smolting, even though more precociously mature males are produced. The salmon that smolt tend to do so at a younger age but also larger size; these trends are predicted to translate into increases in offspring produced per cohort and hence increases in the population size of Atlantic salmon. In Chapter 6, I present an incidental study on the impacts of high summer temperatures on the density and biomass of juvenile Atlantic salmon. High temperatures can result in heat stress in Atlantic salmon, affecting their growth and behaviour. I demonstrate a negative relationship with degree hours exceeding 23ÂșC and the log biomass and log density of juvenile salmon. In the final chapter, I put into context the results of the previous chapters, and address the utility of carcass analogue application as a potential conservation tool. Though the impacts of nutrient additions may vary temporally and may be complex, the data I present in this thesis suggests that nutrient additions may be used as a conservation tool with positive impacts on the freshwater growth of salmon, which is positively related to increases in their marine survival and thus increases at the population level

    2023-2024 Graduate School Catalog

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    You and your peers represent more than 67 countries and your shared scholarship spans 140 programs - from business administration and biomedical engineering to history, horticulture, musical performance, marine science, and more. Your ideas and interests will inform public health, create opportunities for art and innovation, contribute to the greater good, and positively impact economic development in Maine and beyond

    Evaluation Methodologies in Software Protection Research

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    Man-at-the-end (MATE) attackers have full control over the system on which the attacked software runs, and try to break the confidentiality or integrity of assets embedded in the software. Both companies and malware authors want to prevent such attacks. This has driven an arms race between attackers and defenders, resulting in a plethora of different protection and analysis methods. However, it remains difficult to measure the strength of protections because MATE attackers can reach their goals in many different ways and a universally accepted evaluation methodology does not exist. This survey systematically reviews the evaluation methodologies of papers on obfuscation, a major class of protections against MATE attacks. For 572 papers, we collected 113 aspects of their evaluation methodologies, ranging from sample set types and sizes, over sample treatment, to performed measurements. We provide detailed insights into how the academic state of the art evaluates both the protections and analyses thereon. In summary, there is a clear need for better evaluation methodologies. We identify nine challenges for software protection evaluations, which represent threats to the validity, reproducibility, and interpretation of research results in the context of MATE attacks

    Mathematical Problems in Rock Mechanics and Rock Engineering

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    With increasing requirements for energy, resources and space, rock engineering projects are being constructed more often and are operated in large-scale environments with complex geology. Meanwhile, rock failures and rock instabilities occur more frequently, and severely threaten the safety and stability of rock engineering projects. It is well-recognized that rock has multi-scale structures and involves multi-scale fracture processes. Meanwhile, rocks are commonly subjected simultaneously to complex static stress and strong dynamic disturbance, providing a hotbed for the occurrence of rock failures. In addition, there are many multi-physics coupling processes in a rock mass. It is still difficult to understand these rock mechanics and characterize rock behavior during complex stress conditions, multi-physics processes, and multi-scale changes. Therefore, our understanding of rock mechanics and the prevention and control of failure and instability in rock engineering needs to be furthered. The primary aim of this Special Issue “Mathematical Problems in Rock Mechanics and Rock Engineering” is to bring together original research discussing innovative efforts regarding in situ observations, laboratory experiments and theoretical, numerical, and big-data-based methods to overcome the mathematical problems related to rock mechanics and rock engineering. It includes 12 manuscripts that illustrate the valuable efforts for addressing mathematical problems in rock mechanics and rock engineering

    Spatial distribution analysis and application of engineering disturbance disasters in the Himalayan alpine valley

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    The Himalayan alpine canyon area is characterized by complex engineering geological conditions and abnormal internal and external dynamic geological processes. Severe slope disturbance disasters can be caused by engineering disturbances. In this study, field investigations and theoretical analyses were performed to determine the formation mechanism, spatial distribution law, and controlling factors of engineering disturbance disasters in the Himalayan alpine and canyon areas. A total of 396 engineering disturbance disasters were identified within the scope of the 2,800-km survey line. A geographic information system and mathematical statistical analysis were used to analyze the correlation between engineering disturbance disasters and factors such as the slope, slope aspect, elevation, peak ground acceleration, distance from fault, distance from river, rainfall, lithological changes, and historical earthquake effects. The statistical analysis indicates a good power-law and exponential distribution between the engineering disturbance disaster concentration and the slope and distance from the river, respectively. The slope and distance from the river are the two most important factors in determining the spatial distribution of engineering disturbance disasters; the other factors also influence the distribution to some extent. These factors affect the quality of the slope rock and soil mass, affecting slope stability. The main form of engineering disturbance in the study area is slope cutting. The direct result (increase in slope) and secondary result (decrease in rock mass quality caused by unloading rebound) of slope cutting are the most important factors inducing engineering disturbance disasters. Based on previous research results, factors in engineering disturbance disasters in alpine and canyon areas were evaluated, and the distribution of disturbance disasters along the China–Nepal Railway was predicted. The study area was divided into extremely high-(13.6%), high-(30.4%), medium-(34.1%), and low-susceptibility (22.0%) areas. The research results can provide a theoretical basis for prevention and treatment of engineering disturbance disasters in Himalayan alpine valley areas

    Researches regarding the evolution, magnitude and complexity of the impact generated by the economic activities on the East Jiu River

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    Ongoing development of modern society, based on consumption of goods and services, leads to the increase of compulsoriness of economic agents to face market requirements by increasing the degree of local and regional industrialization. Establishment of new economic activities generates negative pressures on the environment and surface waters, generating increased pollution, manifested by vulnerability of aquatic ecosystems to stressors. Preliminary studies carried out within the doctoral thesis entitled 'Research on the evolution, magnitude and complexity of the impact of economic activities on the East Jiu' include information on characteristic elements of the East Jiu River basin, in accordance with the Water Framework Directive 2000/60/CE. The objectives of the field research aimed to identify economic activities in the eastern Jiu Valley generating an impact on the environment (especially the mining industry, but also timber exploitation and processing, local agriculture, animal husbandry and waste storage), establishing a quarterly monitoring program of the river basin, identification of flora and fauna species and identification of areas vulnerable to potential pollution. Based on observations made in situ and on information obtained from the evolution process of the monitoring program, the appropriate methodologies for assessing physical-chemical and ecological quality of the water were selected. Study of the evolution of the impact generated by economic activities on the East Jiu was carried out by mathematical modelling, with finite volumes, of the East Jiu River basin and plotting of pollutant dispersion maps. The magnitude and complexity of impact generated by economic activities was studied by using a complex system based on fuzzy logic, designed based on interactions between natural and artificial systems, between physical-chemical indicators of water and ecosystem. The research carried out substantiates in development of necessary technical measures to reduce the impact generated by economic activities located in eastern Jiu Valley, without significantly changing the hydrodynamics of the river basin. Following research, during different research stages, methods, techniques and tools were designed and accomplished with the help of which, water and aquatic ecosystems’ quality can be assessed, as well as the impact generated by human activity on the Jiu River, at a given moment and/or continuously.:CONTENT ACKNOWLEDGEMENTS SUMMARY LIST OF FIGURES LIST OF TABLES ABBREVIATIONS INTRODUCTION PURPOSE OF THE THESIS AND RESEARCH METHODOLOGY CHAPTER 1 THE EAST JIUL RIVER HYDROGRAPHIC BASIN 1.1. Soil and subsoil of the Eastern part of Jiu Valley 1.2. Climate description of the Eastern part of Jiu Valley 1.3. Geology particularities of the Eastern part of Jiu Valley 1.4. Groundwater features of the Eastern part of Jiu Valley 1.5. Flora and fauna of the Eastern part of Jiu Valley CHAPTER 2 SOURCES OF IMPACT ON THE QUALITY OF WATER, RIPARIAN, TERRESTRIAL AND AQUATIC ECOSYSTEMS 2.1. Mining industry 2.2. Wood processing industry in the Eastern part of Jiu Valley 2.3. Urban agriculture and local animal husbandry 2.4. Inappropriate urban household waste storage CHAPTER 3 MONITORING PROGRAM AND METHODS OF EVALUATION OF THE QUALITY OF THE EAST JIUL RIVER 3.1. Establishment of monitoring (control) sections 3.2. Monitoring program of the East Jiu River basin 3.3. Sampling, transport and analysis of water samples 3.4. Methodology used to establish the water quality CHAPTER 4 QUALITY ASSESSMENT OF WATER IN THE EASTERN JIU HYDROGRAPHIC BASIN 4.1. Section 1 - Jieț River - upstream of household settlements (blank assay) 4.2. Section 2 - East Jiu River - in the area of Tirici village 4.3. Section 3 - Răscoala brook - before the confluence with East Jiu River 4.4. Section 4 - East Jiu River - after the confluence with the Răscoala brook 4.5. Section 5 - Taia River - upstream of the confluence with East Jiu River 4.6. Section 6 - East Jiu River - before the confluence with the Taia River 4.7. Section 7 - East Jiu River - after the confluence with the Taia River 4.8. Section 8 - Jiet River downstream of household settlements 4.9. Section 9 - East Jiu River - after the confluence with the Jieț River 4.10. Section 10 - East Jiu River - before the confluence with Banița River 4.11. Section 11 - RoƟia River - upstream of household settlements 4.12. Section 12 - Bănița River - after the confluence with the Roșia River 4.13. Section 13 - East Jiu River - after the confluence with the Banița River 4.14. Section 14 - Maleia River - before the confluence with East Jiu River 4.15. Section 15 - Slătioara River - before the confluence with East Jiu River 4.16. Section 16 – East Jiu River - before the confluence with West Jiu River CHAPTER 5 INFLUENCES OF PHYSICAL-CHEMICAL FACTORS ON AQUATIC ICHTHYOFAUNA IN THE EAST JIU RIVER BASIN 5.1. Total suspended solids and aquatic ecosystems 5.2. Acidity or basicity reaction of surface watercourses 5.3. Aquatic ecosystem requirements for gas oversaturation 5.4. Nitrogenous compounds in watercourse 5.5. Phenols, aquatic ecosystems and water quality CHAPTER 6 ANALYSIS OF THE IMPACT GENERATED BY ECONOMIC ACTIVITIES IN THE EASTERN PART OF JIU VALLEY 6.1. Impact analysis of mining industry in the Eastern Part of Jiu Valley 6.2. The general impact of Eastern Jiu Valley dumps to water quality 6.3. Research on effective infiltration in the Eastern part of Jiu Valley 6.4. Research on groundwater quality in the Eastern part of Jiu Valley 6.5. Analysis of the impact generated by local micro-agriculture 6.6. Analysis of the impact generated by deforestation and wood processing 6.7. Analysis of the impact generated by non-compliant landfilling of waste CHAPTER 7 EVOLUTION OF THE IMPACT GENERATED BY ECONOMIC ACTIVITIES IN THE EASTERN JIU VALLEY 7.1. Analysis of the dynamic elements of the watercourse - RMA2 mode 7.2. Analysis of pollutants concentration evolution in the water course - RMA4 module 7.3. Computational field and composition of the energy model of the East Jiu River 7.4. Extension and evolution of the impact generated by economic activities on the East Jiu River 7.5. Extension and evolution of the impact caused by organic pollution of the East Jiu River CHAPTER 8 MAGNITUDE AND COMPLEXITY OF THE IMPACT GENERATED BY ECONOMIC ACTIVITIES IN THE EASTERN JIU VALLEY 8.1. Definition of input linguistic variables 8.2. Linguistic outputs of the fuzzy interference system 8.3. Defining the Black Box set of rules 8.4. Proficiency testing of complex systems based on fuzzy logic 8.5. While it is all about the wheel do not forget about the cube CONCLUSIONS AND PERSONAL CONTRIBUTIONS REFERENCE

    University of Arkansas, Chemistry and Biochemistry Department Research Publications, 2014- November 2023. 107p.

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    This report provides a compilation of the research publications by the Chemistry and Biochemistry faculty for the period: 2014 - November 2023. The information was gathered from major databases in science and technology including Web of Science, SciFinder, Reaxys, PubMed, IEEE Explore and Engineering Index. At least one author in each of the publications has the CHBC department as its affiliation. It includes a table summarizing the research. The listing is organized according to type of publications within specific years

    EVALUATION OF EFFECTS OF NEW ANTIFOULING SYSTEMS, ALTERNATIVE TO ORGANOTIN COMPOUNDS, ON BENTHIC MARINE INVERTEBRATES AT ECOSYSTEM, ORGANISMAL AND CELLULAR LEVEL

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    Marine biofouling on anthropic submerged substrata is associated with major ecological and socioeconomic impacts worldwide. The most widely used antifouling systems are chemical ones represented by paints with a biocide, to which booster substances can be added. The latter are highly toxic chemical substances from agriculture (herbicides, fungicides, acaricides, wood preservatives) and pharmaceutical industry (bactericides, fungicides), these cause various ecological problems due to disruptive effects provoked on non-target organisms and depletion of coastal biocoenoses. From 2001, the paints including organotin compounds (TBT and TPT), which had the best performance and were used worldwide for decades, were banned by International Maritime Organization (IMO) after the discovery of their severe impact on the oyster farms. As a consequence of the restrictions on the use of organotin-based paints, finding new antifouling systems has become a primary necessity. Therefore, the research was devoted to new eco-friendly formulations. Regarding Physical antifouling systems have been recently introduced in relation to the development of a more environmentally friendly approach rather than the chemical systems. My scholarship has been entirely financed by RESIMIX s.r.l of Brendola, Vicenza (Italy). The university-enterprise collaboration aimed to develop a new eco-friendly paint. More in general, the research program of my PhD thesis focused on the implementation of new antifouling systems with low effects on benthic marine invertebrates. My PhD activity it was been divided in 2 tasks, i.e., chemical antifouling systems and physical antifouling systems. To determine and compare the effects of these new antifouling systems on both target species (ascidians and mussels) and non-target species (clams) the tasks have been developed at three study levels, i.e., ecosystem, individuals, and cells. As regards of chemical antifouling systems I have been investigated the significant differences in the ecological succession of hard-substratum community, by means of a series of biodiversity indexes, during at least one-year exposure to various RESIMIX paints and trade copper-based paints. In addition, a comparative monitoring with trade antifouling paints has been considered together with the effects on settlement and metamorphosis of ascidian larvae and finally, the observation of the mechanisms of action in in vitro immunotoxicity assays on dominant bioindicators in benthic biocoenoses like tunicates, clams and mussels. From these preliminary but significant results about chemical antifouling systems, crucial questions have arisen regarding the continuous indiscriminate introduction of such biocides into the environment. As regards physical antifouling systems I have been considered geotextiles (for protection from coastal erosion), and ultrasound (to prevent biofilm and disturb the larval settlement) reaching interesting results in both the field and the lab, which revealed the till now hidden downside of these systems.Marine biofouling on anthropic submerged substrata is associated with major ecological and socioeconomic impacts worldwide. The most widely used antifouling systems are chemical ones represented by paints with a biocide, to which booster substances can be added. The latter are highly toxic chemical substances from agriculture (herbicides, fungicides, acaricides, wood preservatives) and pharmaceutical industry (bactericides, fungicides), these cause various ecological problems due to disruptive effects provoked on non-target organisms and depletion of coastal biocoenoses. From 2001, the paints including organotin compounds (TBT and TPT), which had the best performance and were used worldwide for decades, were banned by International Maritime Organization (IMO) after the discovery of their severe impact on the oyster farms. As a consequence of the restrictions on the use of organotin-based paints, finding new antifouling systems has become a primary necessity. Therefore, the research was devoted to new eco-friendly formulations. Regarding Physical antifouling systems have been recently introduced in relation to the development of a more environmentally friendly approach rather than the chemical systems. My scholarship has been entirely financed by RESIMIX s.r.l of Brendola, Vicenza (Italy). The university-enterprise collaboration aimed to develop a new eco-friendly paint. More in general, the research program of my PhD thesis focused on the implementation of new antifouling systems with low effects on benthic marine invertebrates. My PhD activity it was been divided in 2 tasks, i.e., chemical antifouling systems and physical antifouling systems. To determine and compare the effects of these new antifouling systems on both target species (ascidians and mussels) and non-target species (clams) the tasks have been developed at three study levels, i.e., ecosystem, individuals, and cells. As regards of chemical antifouling systems I have been investigated the significant differences in the ecological succession of hard-substratum community, by means of a series of biodiversity indexes, during at least one-year exposure to various RESIMIX paints and trade copper-based paints. In addition, a comparative monitoring with trade antifouling paints has been considered together with the effects on settlement and metamorphosis of ascidian larvae and finally, the observation of the mechanisms of action in in vitro immunotoxicity assays on dominant bioindicators in benthic biocoenoses like tunicates, clams and mussels. From these preliminary but significant results about chemical antifouling systems, crucial questions have arisen regarding the continuous indiscriminate introduction of such biocides into the environment. As regards physical antifouling systems I have been considered geotextiles (for protection from coastal erosion), and ultrasound (to prevent biofilm and disturb the larval settlement) reaching interesting results in both the field and the lab, which revealed the till now hidden downside of these systems
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