579 research outputs found

    Marine Heatwaves in the Chesapeake Bay

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    Prolonged events of anomalously warm sea water temperature, or marine heatwaves (MHWs), have major detrimental effects to marine ecosystems and the world\u27s economy. While frequency, duration and intensity of MHWs have been observed to increase in the global oceans, little is known about their potential occurrence and variability in estuarine systems due to limited data in these environments. In the present study we analyzed a novel data set with over three decades of continuous in situ temperature records to investigate MHWs in the largest and most productive estuary in the US: the Chesapeake Bay. MHWs occurred on average twice per year and lasted 11 days, resulting in 22 MHW days per year in the bay. Average intensities of MHWs were 3°C, with maximum peaks varying between 6 and 8°C, and yearly cumulative intensities of 72°C × days on average. Large co-occurrence of MHW events was observed between different regions of the bay (50–65%), and also between Chesapeake Bay and the Mid-Atlantic Bight (40–50%). These large co-occurrences, with relatively short lags (2–5 days), suggest that coherent large-scale air-sea heat flux is the dominant driver of MHWs in this region. MHWs were also linked to large-scale climate modes of variability: enhancement of MHW days in the Upper Bay were associated with the positive phase of Niño 1+2, while enhancement and suppression of MHW days in both the Mid and Lower Bay were associated with positive and negative phases of North Atlantic Oscillation, respectively. Finally, as a result of long-term warming of the Chesapeake Bay, significant trends were detected for MHW frequency, MHW days and yearly cumulative intensity. If these trends persist, by the end of the century the Chesapeake Bay will reach a semi-permanent MHW state, when extreme temperatures will be present over half of the year, and thus could have devastating impacts to the bay ecosystem, exacerbating eutrophication, increasing the severity of hypoxic events, killing benthic communities, causing shifts in species composition and decline in important commercial fishery species. Improving our basic understanding of MHWs in estuarine regions is necessary for their future predictability and to guide management decisions in these valuable environments

    Structural properties of crumpled cream layers

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    The cream layer is a complex heterogeneous material of biological origin which forms spontaneously at the air-milk interface. Here, it is studied the crumpling of a single cream layer packing under its own weight at room temperature in three-dimensional space. The structure obtained in these circumstances has low volume fraction and anomalous fractal dimensions. Direct means and noninvasive NMR imaging technique are used to investigate the internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy

    Evolutionary Dynamics of Multigene Families in Triportheus (Characiformes, Triportheidae): A Transposon Mediated Mechanism?

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    Triportheus (Characiformes, Triportheidae) is a freshwater fish genus with 18 valid species. These fishes are widely distributed in the major river drainages of South America, having commercial importance in the fishing market, mainly in the Amazon basin. This genus has diverged recently in a complex process of speciation carried out in different river basins. The use of repetitive sequences is suitable to trace the genomic reorganizations occured along the speciation process. In this work, the 5S rDNA multigene family has been characterized at molecular and phylogenetic level. The results showed that other multigene family has been found within the non-transcribed spacer (NTS): the U1 snRNA gene. Double-FISH with 5S and U1 probes were also performed, confirming the close linkage between these two multigene families. Moreover, evidences of different transposable elements (TE) were detected within the spacer, thus suggesting a transposon-mediated mechanism of 5S-U1 evolutionary pathway in this genus. Phylogenetic analysis demonstrated a species-specific grouping, except for Triportheus pantanensis, Triportheus aff. rotundatus and Triportheus trifurcatus. The evolutionary model of the 5S rDNA in Triportheus species has been discussed. In addition, the results suggest new clues for the speciation and evolutionary trend in these species, which could be suitable to use in other Characiformes species

    Saildrone: Adaptively Sampling the Marine Environment

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    From 11 April to 11 June 2018 a new type of ocean observing platform, the Saildrone surface vehicle, collected data on a round-trip, 60-day cruise from San Francisco Bay, down the U.S. and Mexican coast to Guadalupe Island. The cruise track was selected to optimize the science team’s validation and science objectives. The validation objectives include establishing the accuracy of these new measurements. The scientific objectives include validation of satellite-derived fluxes, sea surface temperatures, and wind vectors and studies of upwelling dynamics, river plumes, air–sea interactions including frontal regions, and diurnal warming regions. On this deployment, the Saildrone carried 16 atmospheric and oceanographic sensors. Future planned cruises (with open data policies) are focused on improving our understanding of air–sea fluxes in the Arctic Ocean and around North Brazil Current rings

    Sacrospinous Ligament Suspension With Transobturator Mesh Versus Sacral Colpopexy For Genital Prolapse

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    To compare the safety and efficacy of abdominal sacral colpopexy and sacrospinous ligament suspension with the use of vaginal mesh for apical prolapse. METHOD: This retrospective study was conducted from 2005 to 2012 and included 89 women with apical prolapse who underwent surgery. Assessments included pre- and postoperative Pelvic Organ Prolapse Quantification (POP-Q) stage. Rates of objective cure and immediate/late complications were compared. RESULTS: In total, 41 of the 89 women underwent sacrospinous ligament suspension, and 48 of the women underwent abdominal sacral colpopexy. A total of 40.4% of the women had vault prolapse (p=0.9361). Most of them had no complications (93.2%) (p=0.9418). Approximately 30% of the women had late complications; local pain was the main symptom and was found only in women who underwent the abdominal procedure (25.6%) (p=0.001). Only the women who were submitted to the vaginal procedure had mesh exposure (18.4%). The objective success rate and the rate of anterior vaginal prolapse (p=0.2970) were similar for both techniques. CONCLUSION: Sacrospinous ligament suspension was as effective and had a similar objective success rate as abdominal sacral colpopexy for the treatment of apical prolapse. Sacrospinous ligament suspension performed with the use of vaginal mesh in the anterior compartment was effective in preventing anterior vaginal prolapse after surgery.71948749

    Adoption and impact of marketing performance assessment systems among travel agencies

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    Purpose. The purpose of this paper is to assess whether travel agencies that implement comprehensive marketing performance assessment systems (MPASs) enjoy superior overall performance. Drawing on the Knowledge-Based View, we propose and test a model demonstrating that the relationship between MPASs and overall performance is fully mediated by the depth of market-related knowledge absorbed by the travel agency.Design/methodology/approachA survey was administered to a sample of Italian travel agencies; 171 complete questionnaires were received. The suggested relationships were assessed using a covariance-based structural equation modeling approach, including the estimation of both the measurement model and the structural model. FindingsThe findings indicate that the implementation of sophisticated MPASs has a significant and positive effect on performance and that this relationship is fully mediated by the depth of market-related knowledge absorbed by the travel agency. In addition, the results highlight that the number of marketing metrics monitored by the travel agency has no effect on its performance.Research limitations/implicationsThe specific features of the travel agency sector in Italy include a remarkable level of fragmentation. The cross-sectional design does not permit an assessment of the medium-term effects of the adoption of an MPAS.Practical implicationsTravel agencies selecting proactive marketing strategies can particularly benefit from the adoption of sophisticated MPASs. Suggestions are provided to assist managers in designing their MPAS.Originality/valueThis study enriches the field’s knowledge about marketing performance measurement and proactive marketing strategies and indicates that the implementation of well-designed marketing performance assessment systems improves a firm’s overall performance. It also explains the knowledge-related processes that produce this positive effect

    Simulation–Optimization Modeling: A Survey and Potential Application in Reservoir Systems Operation

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    This paper presents a survey of simulation and optimization modeling approaches used in reservoir systems operation problems. Optimization methods have been proved of much importance when used with simulation modeling and the two approaches when combined give the best results. The main objective of this review article is to discuss simulation, optimization and combined simulation– optimization modeling approach and to provide an overview of their applications reported in literature. In addition to classical optimization techniques, application and scope of computational intelligence techniques, such as, evolutionary computa- tions, fuzzy set theory and artificial neural networks, in reservoir system operation studies are reviewed. Conclusions and suggestive remarks based on this survey are outlined, which could be helpful for future research and for system managers to decide appropriate methodology for application to their systems
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