The Biology of the Flounder, Platichthys flesus L. (Pisces: Pleuronectidae) in the Thames, a Polluted Estuary.

PhDFlounders (Platichthys flesus L. ) were sampled from the cooling water intake screens of West Thurrock power station, Essex, from September 1987 to October 1990. Changes in population structure are determined from age and morphometric data. Adult flounders congregate in the mid-estuary in late spring, prior to their spawning migration. New recruits arrive in the estuary in summer and disperse upstream after a few weeks. Dispersal appears to involve density-dependant population regulating mechanisms. Growth appears seasonal to an extent, being reduced during winter months. The gut contents were analysed and a trophic spectrum constructed. P. flesus is an opportunist predator, feeding predominantly on crustaceans in the mid estuary and molluscs in the outer estuary. There is some evidence of resource partitioning between adult and juvenile flounders. The significance of changes in the lipid reserves of 0-group flounders is discussed. The seasonal dynamics of external disease symptoms and parasite burden of these fish was evaluated, and related to population structure, dietary condition and water quality variables. 2 The prevalence of all external disease in flounders from Kest Thurrock is closely related to population structure. Younger fish generally display lower disease prevalences. -Increased prevalence of lymphocystis may be related to increases in the prevalence of ulcerations or heavy infections by the copepod Lepeophtheirus pectoralis. A correlation between the minimum monthly dissolved oxygen (D. O. ) level and the condition factor of flounders is demonstrated. Fewer epidermal ulcers are observed on flounders with a high condition factor. The prevalence of epidermal ulcerations, and to an extent lymphocystis, are thus indirectly associated with estuarine pollution. The use of external disease prevalence as a bioindicator of estuarine pollution is considered. Live flounders were observed in various lighting regimes using time-lapse video techniques to determine the nature and extent of intrinsic rhythmic behaviour. Observations were made on the behaviour modifying effects of contaminated sediments and hypoxic conditions. The findings are discussed in relation to the ecology of the flounder in the Thames estuary

Study of the Effect of Steam Injection on Crude Oil Displacement Yield from an Oil Contaminated Soil Bed

A substantial oil recovery of different packed soil samples has been obtained by the removal of light and heavy crude oils, with different American Petroleum Institute (API) gravity indexes. Steam and water injection methods are applied to different soil particle size samples (core size) and different types of oil gravity. The amount of oil removed increases with increasing the core size (permeability and porosity). For 0.5 mm core size and light oil (35-API), oil recovery reaches 98 wt% using superheated steam and 96 wt% using saturated steam. For heavy oil (24-API), oil recovery reaches 91 wt% using superheated steam and 90 wt% using saturated steam. For 0.2mm core size and heavy oil (24-API), oil recovery reaches 85% using superheated steam and 74 wt% using saturated steam. These results suggest that oil recovery increases as cell temperature and core size (permeability and porosity) increase, and the addition of surfactants to steam increased oil recovery amounting to around 3 wt%. Water injection resulted in low oil recovery, and the maximum oil recovery is 5 wt%, and 20 wt% using cold and hot water, respectively

Statistical ensemble of gene regulatory networks of macrophage differentiation

Background: Macrophages cover a major role in the immune system, being the most plastic cell yielding several key immune functions. Methods: Here we derived a minimalistic gene regulatory network model for the differentiation of macrophages into the two phenotypes M1 (pro-) and M2 (anti-inflammatory). Results: To test the model, we simulated a large number of such networks as in a statistical ensemble. In other words, to enable the inter-cellular crosstalk required to obtain an immune activation in which the macrophage plays its role, the simulated networks are not taken in isolation but combined with other cellular agents, thus setting up a discrete minimalistic model of the immune system at the microscopic/intracellular (i.e., genetic regulation) and mesoscopic/intercellular scale. Conclusions: We show that within the mesoscopic level description of cellular interaction and cooperation, the gene regulatory logic is coherent and contributes to the overall dynamics of the ensembles that shows, statistically, the expected behaviour

A Mathematical Framework for Agent Based Models of Complex Biological Networks

Agent-based modeling and simulation is a useful method to study biological phenomena in a wide range of fields, from molecular biology to ecology. Since there is currently no agreed-upon standard way to specify such models it is not always easy to use published models. Also, since model descriptions are not usually given in mathematical terms, it is difficult to bring mathematical analysis tools to bear, so that models are typically studied through simulation. In order to address this issue, Grimm et al. proposed a protocol for model specification, the so-called ODD protocol, which provides a standard way to describe models. This paper proposes an addition to the ODD protocol which allows the description of an agent-based model as a dynamical system, which provides access to computational and theoretical tools for its analysis. The mathematical framework is that of algebraic models, that is, time-discrete dynamical systems with algebraic structure. It is shown by way of several examples how this mathematical specification can help with model analysis.Comment: To appear in Bulletin of Mathematical Biolog

Mixing & solidification Processing of AI-AI2o3 Composite

In the present investigation, mixing has been carried out by dispersing fine alumina particles (Avg. size- 25 µm) in molten Al-Mg alloy using a turbine blade stirrer with impeller diameter 'd'. The molten alloy has a depth of H when kept in a crucible of diameter D and the stirrer is placed at height 'h' from its bottom. The dimensionless variables. d/D and h/H, have been varied to observe the dependence of optimum values of these variables on stirrer geometry. These studies are expected to contribute to optimum processing route for stircasting of composites. In the current investigation, it has been observed that a turbine stirrer incorporates higher aunount of particles in the ingot cast out of a slurry mixed by it as compared to a flat blade stirrer in the range of experimental parameters used. But the pore-particle ratio is also higher in the cast ingot processed by a turbine stirrer. In the cast ingots processed by a turbine stirrer the particle content increases when d/D ratio increased from 0.33 to 0.48 but a further increase of d/D to 0.62 did not change significantly the particle content. A similar trend in pore-particle ratio is also observed and the lowest poreparticle ratio was observed for d/D=0.62. For mixing a slurry of molten alloy with poorly wetting particles it appears that the recommendation of chemical engineers to keep the stirrer at h/H=0.35 may not work as well from the point of view of particle content in the ingot cast with the slurry. By enhancing h/H to 0.5, the particle content increased significantly and a lower pore-particle ratio was also achieved.The microstructural evidence clearly indicates formation of bubbles with particles adhering to it and even their coalescence during processing. Some of these bubbles are eventually invaded by the molten alloy. When the manner of stirring is changed from continuous four minutes to an interrupted one of two minutes each intervened by a two minute period of cessation of tirring, it has been observed that the particle content at the top reduces but that at the bottom increases making particle content more uniform along the length of the ingot. This has been attributed to enhanced floatation of bubbles containing particles and reincorporation of the latter. During interrupted stirring the porosity did not reduce as unuch as the particles and the poreparticle ratio at the top increased. Enhanced processing time may have contributed to 10increased dissolution of gases contributing to porosity and so3 a reduced extent of bubble-particle combine did not reduce the overall porosity as much as it was expected. When the stirring was interrupted fora longer time of 10 minutes the uniformity of the ingot in respect of particle content improved to an extent but the overall porosity increased significantly. These facts possibly indicate that most of bubbleparticle combines form during mixing and not during solidification

In Defence of Absolutes: The Evolution of Aphra Behns Political Views

The evolution of Aphra Behns political views is a point of scholarly contention. The analysis of her dramatic works starts with her early tragicomedies, like The Young King and The Amorous Prince, and continues through her well- known Exclusion Crisiss sexual comedies, like The Roundheads and Sir Patient Fancy. This paper argues that Behns on- stage royalism was considerably diverse, reflecting various degrees of support for the monarchy. Behn altered her political positions in response to the development of the fierce rivalry between different political parties. Following her concerns and discontent about the kings ability to rule the country in her early plays, Behn developed a remarkable tendency for supporting Charles II and created an image of an impeccable king beyond any criticism. The results suggest that Behn’s Toryism did not reflect an unwavering and unchanging support for the newly restored monarchy, as was assumed previously

Gene regulatory network modeling of macrophage differentiation corroborates the continuum hypothesis of polarization states

Macrophages derived from monocyte precursors undergo specific polarization processes which are influenced by the local tissue environment: classically activated (M1) macrophages, with a pro-inflammatory activity and a role of effector cells in Th1 cellular immune responses, and alternatively activated (M2) macrophages, with anti-inflammatory functions and involved in immunosuppression and tissue repair. At least three different subsets of M2 macrophages, namely, M2a, M2b, and M2c, are characterized in the literature based on their eliciting signals. The activation and polarization of macrophages is achieved through many, often intertwined, signaling pathways. To describe the logical relationships among the genes involved in macrophage polarization, we used a computational modeling methodology, namely, logical (Boolean) modeling of gene regulation. We integrated experimental data and knowledge available in the literature to construct a logical network model for the gene regulation driving macrophage polarization to the M1, M2a, M2b, and M2c phenotypes. Using the software GINsim and BoolNet, we analyzed the network dynamics under different conditions and perturbations to understand how they affect cell polarization. Dynamic simulations of the network model, enacting the most relevant biological conditions, showed coherence with the observed behavior of in vivo macrophages. The model could correctly reproduce the polarization toward the four main phenotypes as well as to several hybrid phenotypes, which are known to be experimentally associated to physiological and pathological conditions. We surmise that shifts among different phenotypes in the model mimic the hypothetical continuum of macrophage polarization, with M1 and M2 being the extremes of an uninterrupted sequence of states. Furthermore, model simulations suggest that anti-inflammatory macrophages are resilient to shift back to the pro-inflammatory phenotype

Protein contact map prediction using multi-stage hybrid intelligence inference systems

AbstractProteins are one of the most important molecules in organisms. Protein function can be inferred from its 3D structure. The gap between the number of discovered protein sequences and the number of structures determined by the experimental methods is increasing. Accurate prediction of protein contact map is an important step toward the reconstruction of the protein’s 3D structure. In spite of continuous progress in developing contact map predictors, highly accurate prediction is still unresolved problem. In this paper, we introduce a new predictor, JUSTcon, which consists of multiple parallel stages that are based on adaptive neuro-fuzzy inference System (ANFIS) and K nearest neighbors (KNNs) classifier. A smart filtering operation is performed on the final outputs to ensure normal connectivity behaviors of amino acids pairs. The window size of the filter is selected by a simple expert system. The dataset was divided into testing dataset of 50 proteins and training dataset of 450 proteins. The system produced an average accuracy of 45.2% for the sequence separation of six amino acids. In addition, JUSTcon outperformed SVMcon and PROFcon predictors in the cases of large separation distances. JUSTcon produced an average accuracy of 15% for the sequence separation of 24 amino acids after applying it on CASP9 targets