1,241 research outputs found

    Synthetic Aperture Radar (SAR) Meets Deep Learning

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    This reprint focuses on the application of the combination of synthetic aperture radars and depth learning technology. It aims to further promote the development of SAR image intelligent interpretation technology. A synthetic aperture radar (SAR) is an important active microwave imaging sensor, whose all-day and all-weather working capacity give it an important place in the remote sensing community. Since the United States launched the first SAR satellite, SAR has received much attention in the remote sensing community, e.g., in geological exploration, topographic mapping, disaster forecast, and traffic monitoring. It is valuable and meaningful, therefore, to study SAR-based remote sensing applications. In recent years, deep learning represented by convolution neural networks has promoted significant progress in the computer vision community, e.g., in face recognition, the driverless field and Internet of things (IoT). Deep learning can enable computational models with multiple processing layers to learn data representations with multiple-level abstractions. This can greatly improve the performance of various applications. This reprint provides a platform for researchers to handle the above significant challenges and present their innovative and cutting-edge research results when applying deep learning to SAR in various manuscript types, e.g., articles, letters, reviews and technical reports

    Marine Toxins from Harmful Algae and Seafood Safety

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    The rapid expansion of aquaculture around the world is increasingly being impacted by toxins produced by harmful marine microalgae, which threaten the safety of seafood. In addition, ocean climate change is leading to changing patterns in the distribution of toxic dinoflagellates and diatoms which produce these toxins. New approaches are being developed to monitor for harmful species and the toxins they produce. This Special Issue covers pioneering research on harmful marine microalgae and their toxins, including the identification of species and toxins; the development of new chemical and biological techniques to identify and monitor species and toxins; the uptake of marine biotoxins in seafood and marine ecosystems; and the distribution and abundance of toxins, particularly in relation to climate change

    On advances, challenges and potentials of remote sensing image analysis in marine debris and suspected plastics monitoring

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    Marine plastic pollution is an emerging environmental problem since it pollutes the ocean, air and food whilst endangering the ocean wildlife via the ingestion and entanglements. During the last decade, an enormous effort has been spent on finding possible solutions to marine plastic pollution. Remote sensing imagery sits in a crucial place for these efforts since it provides informative earth observation products, and the current technology offers further essential development. Despite the advances in the last decade, there is still a way to go for marine plastic monitoring research where challenges are rarely highlighted. This paper contributes to the literature with a critical review and aims to highlight literature milestones in marine debris and suspected plastics (MD&SP) monitoring by promoting the computational imaging methodology behind these approaches along with detailed discussions on challenges and potential future research directions

    LINKING THE ENZYMATIC REPERTOIRE OF HETEROTROPHIC BACTERIA TO COMMUNITY COMPOSITION, CARBOHYDRATE INVENTORIES, AND PHYSICAL OCEANOGRAPHY IN THE WESTERN NORTH ATLANTIC

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    The balance of carbon between the atmosphere and ocean—which ultimately impacts the Earth’s climate—is dependent upon the production of organic matter by algae and its fate after being processed by heterotrophic microorganisms. In fact, heterotrophic bacteria—which can be particle-associated or free-living—are responsible for processing an estimated half of the organic matter that phytoplankton synthesize in the surface ocean. A large proportion of this organic matter is in the form of polysaccharides, or structurally complex, high molecular weight sugars. To transform this complex organic matter, microbes must produce enzymes of the correct structural specificity to transform it to smaller pieces that can be brought into the cell. The extent and rates to which bacteria can hydrolyze organic matter determines how much carbon is transformed for a given microbial community. Because microbial community composition differs with location and depth in the ocean, quantifying the enzymatic activities and complexity of organic matter at different stations and depths is essential to measuring patterns in microbial functional capabilities. Links between microbial community composition, their enzymatic function, and the structural complexity of the organic matter that they process are only beginning to be established. This dissertation focuses on characterizing the hydrolysis rates and substrate specificities of extracellular enzymes from three cruises in the western North Atlantic, leading to insights into the way the structural complexity of organic matter may be linked to differences in measured activities. We found that 1) bacteria on particles have an enhanced capability to degrade organic matter; 2) regional patterns of polysaccharide hydrolase activities could be driven by the physical oceanography of the region; and 3) the structural complexity of polysaccharides differed considerably by location, even though their monosaccharide building blocks were similar. The data and findings presented here highlight the extent to which microbial community composition and function, the structural complexity of organic matter, and the physical oceanography of the western North Atlantic are interwoven and contribute to the overall transformation of carbon in the ocean.Doctor of Philosoph

    The Western Channel Observatory: a century of physical, chemical and biological data compiled from pelagic and benthic habitats in the western English Channel

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    The Western Channel Observatory (WCO) comprises a series of pelagic, benthic and atmospheric sampling sites within 40 km of Plymouth, UK, that have been sampled by the Plymouth institutes on a regular basis since 1903. This longevity of recording and the high frequency of observations provide a unique combi�nation of data; for example temperature data were first collected in 1903, and the reference station L4, where nearly 400 planktonic taxa have been enumerated, has been sampled on a weekly basis since 1988. While the component datasets have been archived, here we provide the first summary database bringing together a wide suite of the observations. This provides monthly average values of some of the key pelagic and benthic measure�ments for the inshore site L4 (50◦15.000 N, 4◦13.020 W; approx. depth 55 m), the offshore site E1 (50◦02.000 N, 4 ◦22.000 W; approx. depth 75 m) and the intermediate L5 site (50◦10.800 N, 4◦18.000 W; approx. depth 58 m). In brief, these data include the following: water temperature (from 1903); macronutrients (from 1934); dissolved inorganic carbon and total alkalinity (from 2008); methane and nitrous oxide (from 2011); chlorophyll a (from 1992); high-performance liquid chromatography (HPLC)-derived pigments (from 1999); <20 µm plankton by flow cytometry, including bacteria (8 functional groups from 2007); phytoplankton by microscopy (6 functional groups from 1992); microplankton and mesozooplankton from FlowCam (6 groups from 2012); Noctiluca sp. dinoflagellate (from 1997); mesozooplankton by microscopy (8 groups from 1988); Calanus helgolandicus egg production rates (from 1992); fish larvae from the Young Fish Trawl survey (4 groups from 1924); benthic macrofauna (4 groups from 2008); demersal fish (19 families from 2008); blue shark, Prionace glauca (from 1958); and 16S alpha diversity for sediment and water column (from 2012). These data have varying coverage with respect to time and depth resolution. The metadata tables describe each dataset and provide pointers to the source data and other related Western Channel Observatory datasets and outputs not compiled here. We pro�vide summaries of the main trends in seasonality and some major climate-related shifts that have been revealed over the last century. The data are available from the Data Archive for Seabed Species and Habitats (DASSH): https://doi.org/10.17031/645110fb81749 (McEvoy and Atkinson, 2023). Making these data fully accessible and including units of both abundance and biomass will stimulate a variety of uptakes. These may include uses as an educational resource for projects, for models and budgets, for the analysis of seasonality and long-term change in a coupled benthic–pelagic system, or for supporting UK and north-eastern Atlantic policy and management

    Antarctica: an inchoate threat to New Zealand’s Security: implications for national policy and the Armed Services

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    National interest has always exerted a significant influence over the geopolitical affairs of Antarctica. During the first half of the twentieth century national interest was fuelled by the inimical politics of whaling, which of itself created tension amongst those states that had a presence on the Antarctic continent. With the ratification of the Antarctic Treaty in 1961 international anxiety over the prospect of Antarctica becoming a superpower playground with nuclear overtones subsided and the world community accepted an obligation to forthwith protect the continent and its unique environment. However, the advent of the Treaty has not curbed the aspirations of state and non-state parties to exploit Antarctica for both its living and non-living resources. Commercial pressure to gain access to Antarctic resources is likely to intensify in the future once exploitable resources elsewhere in the world become increasingly scarce. Reserves of several strategic resources are projected to reach the point of commercial exhaustion within the first three decades of the 21st century. In the Arctic access to resources such as oil and fish continues to sour relations between otherwise friendly countries and was, in part, is responsible for the militarization of the Arctic Ocean region. If the Arctic represents Antarctica's prophetic twin then New Zealand will face an international relations dilemma unlike any it has previously confronted: should it defend its territorial claim over the Ross dependency or withdraw northwards to secure a Sub-Antarctic bastion? This is a rhetorical question for without being part of an amiable union of countries, securing the Ross dependency will be impossible for New Zealand to achieve. Given that such a union cannot be assured, it is in New Zealand's national interest to be militarily prepared to defend its Sub-Antarctic 'backyard'. Military preparedness in New Zealand is determined by national policy, an amalgam of foreign affairs and defence considerations, which in recent years have failed to recognise Antarctica as an inchoate security threat. Consequently, the New Zealand Defence Forces, despite recent capability upgrades, remain inappropriately equipped and ill-prepared to confront any challenge to the territorial integrity of New Zealand's Sub-Antarctic 'backyard' and the resources it may harbour

    Portugal and the Constitution for the Oceans: The United Nations Convention on the Law of the Sea 40 Years Later

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    Ciguatoxins

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    Ciguatoxins (CTXs), which are responsible for Ciguatera fish poisoning (CFP), are liposoluble toxins produced by microalgae of the genera Gambierdiscus and Fukuyoa. This book presents 18 scientific papers that offer new information and scientific evidence on: (i) CTX occurrence in aquatic environments, with an emphasis on edible aquatic organisms; (ii) analysis methods for the determination of CTXs; (iii) advances in research on CTX-producing organisms; (iv) environmental factors involved in the presence of CTXs; and (v) the assessment of public health risks related to the presence of CTXs, as well as risk management and mitigation strategies
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