170 research outputs found
Abundance and morphology of Paleodictyon nodosum, observed at the Clarion-Clipperton Zone
Paleodictyon is an important trace fossil characterised by a regular hexagonal structure and typical of ancient deep-ocean habitats as far back as the Ordovician. It is represented in modern deep-sea settings by Paleodictyon nodosum, known from the Mid-Atlantic Ridge, the South Atlantic, and off eastern Australia. Here we report the occurrence of P. nodosum in the Clarion Clipperton Zone (CCZ), abyssal equatorial Pacific, an area characterised by polymetallic nodule fields. At the study site within the International Seabed Authority northeastern Area of Particular Environmental Interest (APEI-6), P. nodosum appeared as a compact, regular pattern of small circular openings on the seafloor, each pattern interpreted as reflecting the activity of an individual organism. The patterns had a mean size (maximum dimension) of 45 mm?±?16 mm SD (n?=?841) and occurred at a density of 0.33 individuals m?2. Most (82%) were interrupted by nodules, but those that were not displayed both regular (59%) and irregular (41%) forms, the former having equal numbers of rows along the three axes (6 x 6 x 6 and 8 x 8 x 8). In both size and morphology, our Paleodictyon traces were more similar to the Australian examples than to those from the Mid-Atlantic Ridge
Understanding the Relationships Between Lightning, Cloud Microphysics, and Airborne Radar-derived Storm Structure During Hurricane Karl (2010)
This study explores relationships between lightning, cloud microphysics, and tropical cyclone (TC) storm structure in Hurricane Karl (16 September 2010) using data collected by the NASA DC-8 and Global Hawk (GH) aircraft during NASA's Genesis and Rapid Intensification Processes (GRIP) experiment. The research capitalizes on the unique opportunity provided by GRIP to synthesize multiple datasets from two aircraft and analyze the microphysical and kinematic properties of an electrified TC. Five coordinated flight legs through Karl by the DC-8 and GH are investigated, focusing on the inner-core region (within 50km of the storm center) where the lightning was concentrated and the aircraft were well coordinated. GRIP datasets are used to compare properties of electrified and nonelectrified inner-core regions that are related to the noninductive charging mechanism, which is widely accepted to explain the observed electric fields within thunderstorms. Three common characteristics of Karl's electrified regions are identified: 1) strong updrafts of 10-20ms21, 2) deep mixed-phase layers indicated by reflectivities.30 dBZ extending several kilometers above the freezing level, and 3) microphysical environments consisting of graupel, very small ice particles, and the inferred presence of supercooled water. These characteristics describe an environment favorable for in situ noninductive charging and, hence, TC electrification. The electrified regions in Karl's inner core are attributable to a microphysical environment that was conducive to electrification because of occasional, strong convective updrafts in the eyewall
Service encounter conceptualisation:employees' service behaviours and customers' service quality perceptions
The enhancement of service quality is an area of optimal managerial relevance that has, to date, received minimal attention in the literature. Because customers' service quality evaluations are based almost entirely upon the behaviours of frontline employees, organisations rely heavily upon these employees to improve overall service quality provision. However, much of the literature looking at service quality enhancement lacks detail when examining the impact of employee service-related behaviours on customers' service quality perceptions. As a result, this paper comprehensively conceptualises those front-line employee behaviours which are the most likely to enhance customers' service quality perceptions. This conceptualisation is grounded in an extensive review of the services marketing literature, pooling together previously disparate research strands. Formal hypotheses are presented. Implications and future research directions are also discussed
A model of service performance enhancement:the role of transactional and transformational leadership
This paper is concerned with the ways in which transactional and transformational leadership styles can improve the service performance of front-line staff. Past literature on services marketing has indicated the importance of leadership but has largely ignored the parallel literature in which leadership styles have been conceptualized and operationalized (e.g., sales management, organizational psychology). This paper seeks to build upon existing services marketing theory by introducing the role of leadership styles in enhancing service performance. Consequently, a conceptual framework of the effect of transactional and transformational leadership styles on service performance, anchored in a crossdisciplinary literature review, is developed. Managerial implications and future research directions are also discussed
A model of transactional and transformational leadership for services personnel
This paper is concerned with the effects that leadership styles (i.e., transactional and transformational) can have upon the level of front-line employees’ service delivery quality. Previous literature has mostly looked at leadership and its effects upon subordinates within a sales, psychology, or human resources context. However, due to the idiosyncrasies inherent in services (i.e., intangibility, heterogeneity, perishability, and inseparability), it is likely that, in such a context, different leadership styles will effect performance outcomes. Consequently, this paper seeks to expand the services marketing literature by developing a conceptual framework of leadership style effects adapted to the field of services marketing. Of particular importance are the effects that leadership styles have upon front-line employee “motivators” and service-related job outcomes. Specific hypotheses are developed and future research directions are also presented for consideration
Biological responses to disturbance from simulated deep-sea polymetallic nodule mining
Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities
SERPENT Activity Report: Lincoln 205/26b-14 and Warwick Crestal. 2019. UK.
In 2019 National Oceanography Centre scientists carried out a field campaign at Hurricane Energy’s Lincoln 205/26b-14 and Warwick Crestal 204/30b-A sites west of Shetland, through Hurricane’s involvement in the SERPENT Project.
Previous SERPENT observations have revealed the impacts of sedimentation disturbance from the open hole phase of hydrocarbon drilling. This work showed some evidence for different faunal responses over time following the sedimentation event, including evidence for recovery of the abundance and diversity of organisms living within the impacted area. The interpretation of these changes is limited because data only exist over coarse time scales necessary when completing visits pre-drilling, post-drilling and return visits to the sites (e.g. months to years).
The primary aim of the field visits to the Transocean Leader in 2019 were to understand the responses of seafloor organisms to sedimentation disturbance over finer temporal scales (e.g. minutes to hours) within the context of the existing knowledge of the effects of sedimentation at hydrocarbon drilling sites. This was addressed using seafloor video survey techniques and time-lapse photography of seafloor organisms during sedimentation events
Xenophyophores (Rhizaria, Foraminifera), including four new species and two new genera, from the western Clarion-Clipperton Zone (abyssal equatorial Pacific)
The Clarion-Clipperton Zone (CCZ) occupies a vast swathe of the Pacific with extensive polymetallic nodule deposits. Eastern and central parts host diverse assemblages of xenophyophores (megafaunal agglutinated foraminifera). Here we describe xenophyophores obtained using a Remotely Operated Vehicle from the western CCZ. Eleven distinct forms include two known species, Stannophyllum zonarium Haeckel, 1888 and Aschemonella monile Gooday and Holzmann in Gooday et al., 2017b. Another four are described as new species based on morphological and genetic data. In Abyssalia foliformis gen. nov., sp. nov. and Abyssalia sphaerica sp. nov. the flattened or spherical test comprises a homogeneous framework of sponge spicules. Psammina tenuis sp. nov. has a delicate, thin, plate-like test. Moanammina semicircularis gen. nov., sp. nov. has a stalked, fan-shaped test and is genetically identical to ‘Galatheammina sp. 6’ of Gooday and co-workers from the eastern CCZ. Sequence data revealed a spherical ‘mudball’, which disintegrated and cannot be formally described, to be a novel xenophyophore. Finally, four morphospecies are represented by dead tests: Psammina spp., Reticulammina sp., and an unknown genus with a unique test structure. This collection enhances our knowledge of Pacific xenophyophore diversity and provides the first genetic confirmation of wide geographic ranges for abyssal species
Agglutination of benthic foraminifera in relation to mesoscale bathymetric features in the abyssal NE Atlantic (Porcupine Abyssal Plain)
Abyssal hills, small topographic features rising above the abyssal seafloor (< 1000 m altitude), have distinct environmental characteristics compared to abyssal plains, notably the presence of coarser-grained sediments. As a result, they are a major source of habitat heterogeneity in the deep sea. The aim of this study was to investigate whether there is a link between abyssal hills and the test characteristics of selected agglutinated benthic foraminiferal species. We analysed 1) the overall morphometry, and 2) the granulometric and chemical (elemental) characteristics of the agglutinated tests of ten common foraminiferal species (Adercotryma glomerata, Ammobaculites agglutinans, Cribrostomoides subglobosus, Lagenammina sp.1, Nodulina dentaliniformis, Portatrochammina murrayi, three Reophax sp. and Recurvoides sp. 9) at four sites (two on top of abyssal hills and two on the adjacent plain) in the area of the Porcupine Abyssal Plain Sustained Observatory, northeast Atlantic. The foraminiferal test data were compared with the particle size distribution and elemental composition of sediments from the study sites in order to explore possible grain size and mineral selectivity. We found differences in the visual appearance of the tests (i.e. the degree of irregularity in their shape), which was confirmed by morphometric analyses, related to seafloor topography. The agglutinated foraminifera selected different sized particles on hills and plains, reflecting the distinct granulometric characteristics of these settings. These characteristics (incorporation of coarse particles, test morphometry) could provide evidence for the recognition of ancient abyssal hill environments, as well as other palaeoceanographic settings that were characterised by enhanced current flow. Furthermore, analyses of sediment samples from the hill and plain sites using wavelength dispersive X-ray fluorescence (WD-XRF) yielded different elemental profiles from the plains, probably a result of winnowing on the hills, although all samples were carbonate-rich. In contrast, the majority of the agglutinated tests were rich in silica, suggesting a preferential selection for quartz
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