Interactive Effects Of Domoic Acid Allelopathy, Salinity, And Eutrophication On Estuarine Phytoplankton Community Structure

Coastal regions and estuaries are particularly sensitive to the increase in nutrient loading and river runoff, threatening the ecosystems with possible spreads in harmful algal blooms (HABs). As an example, blooms of toxic Pseudo-nitzschia species can release acute concentrations of the neurotoxin domoic acid (DA) in the water column. When ingested at concentrations higher than 20 ppm, DA can cause the death of marine birds, marine mammals and even humans. The main objectives of my research were to determine the drivers of Pseudo-nitzschia abundance and toxicity and to assess how these drivers influenced the phytoplankton community structure and DA allelopathy. Through multiple bioassays using water collected from two sites, North Inlet (high salinity, nutrient deplete) and Winyah Bay (low salinity, nutrient replete), links between the environmental factors and Pseudo-nitzschia abundances and toxicity were investigated. Subsequent experiments determined the influence of salinity on DA allelopathy. Finally, the impact of moderate loadings of nitrate and phosphate on Pseudo-nitzschia abundance, DA allelopathy and on the entire phytoplankton community composition were examined. The major conclusions of this research are: 1. In North Inlet, increases in Pseudo-nitzschia abundance and toxicity were driven by low temperatures and high salinity. In Winyah Bay, Pseudo-nitzschia cells were present but had difficulties acclimating to low salinities. 2. DA allelopathy was more effective on salinity-stressed cells (i.e. high salinity in North Inlet, low salinity in Winyah Bay). 3. Although the addition of nutrients enhanced Pseudo-nitzschia abundance, it decreased the effect of DA on natural phytoplankton communities and mitigated the influence of salinity on DA allelopathy. 4. Significant shifts in the phytoplankton community composition with the addition of nutrients were observed although the threshold of 40 μg chl a l-1 wasn’t reached. But no shift towards a particular group was established. My findings highlight how environmental factors such as salinity and nutrients can play important roles on Pseudo-nitzschia abundance as well as on DA allelopathy by alleviating or exacerbating its effect. Furthermore, with a possible increase in HABs due to eutrophication, my results demonstrate the ecological risk of using a subjective chl a concentration based on total phytoplankton biomass for water quality criteria. Relative abundances of algal groups and species should be included to be able to identify harmful species

The contemporary values of operadiction regimes

Regimes of operadiction simultaneously produce both their own governance scripts and the ontology of their operation, the realities in which they apply. Regimes of operadiction and veridiction share aspects of open-ended and adaptive modes of governance. The veridiction regime operates as a sort of knowledge tool, to produce a governmental truth capable of affirming the powers appropriate to manage a population, to maximize the population's productivity under competitive conditions that constantly require more production. As a descriptor of the utility of data in neural network processes, value is a function of accuracy and signal strength. Critique of classical regimes has been organized around the representations made by or associated with international legal regimes and instruments, seeking out the space between the representation and reality, between the guiding norm and the concrete institutional effect, to demonstrate divergence there

On the merits of SVC-based HTTP adaptive streaming

HTTP Adaptive Streaming (HAS) is quickly becoming the dominant type of video streaming in Over-The-Top multimedia services. HAS content is temporally segmented and each segment is offered in different video qualities to the client. It enables a video client to dynamically adapt the consumed video quality to match with the capabilities of the network and/or the client's device. As such, the use of HAS allows a service provider to offer video streaming over heterogeneous networks and to heterogeneous devices. Traditionally, the H. 264/AVC video codec is used for encoding the HAS content: for each offered video quality, a separate AVC video file is encoded. Obviously, this leads to a considerable storage redundancy at the video server as each video is available in a multitude of qualities. The recent Scalable Video Codec (SVC) extension of H. 264/AVC allows encoding a video into different quality layers: by dowloading one or more additional layers, the video quality can be improved. While this leads to an immediate reduction of required storage at the video server, the impact of using SVC-based HAS on the network and perceived quality by the user are less obvious. In this article, we characterize the performance of AVC- and SVC-based HAS in terms of perceived video quality, network load and client characteristics, with the goal of identifying advantages and disadvantages of both options

An autonomic delivery framework for HTTP adaptive streaming in multicast-enabled multimedia access networks

The consumption of multimedia services over HTTP-based delivery mechanisms has recently gained popularity due to their increased flexibility and reliability. Traditional broadcast TV channels are now offered over the Internet, in order to support Live TV for a broad range of consumer devices. Moreover, service providers can greatly benefit from offering external live content (e. g., YouTube, Hulu) in a managed way. Recently, HTTP Adaptive Streaming (HAS) techniques have been proposed in which video clients dynamically adapt their requested video quality level based on the current network and device state. Unlike linear TV, traditional HTTP- and HAS-based video streaming services depend on unicast sessions, leading to a network traffic load proportional to the number of multimedia consumers. In this paper we propose a novel HAS-based video delivery architecture, which features intelligent multicasting and caching in order to decrease the required bandwidth considerably in a Live TV scenario. Furthermore we discuss the autonomic selection of multicasted content to support Video on Demand (VoD) sessions. Experiments were conducted on a large scale and realistic emulation environment and compared with a traditional HAS-based media delivery setup using only unicast connections

IPTV deployment - Trigger for advanced network services!

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