Long-term freshwater input and sediment load from three tributaries to Lake Pontchartrain, Louisiana

Lake Pontchartrain and the drainage basin have experienced environmental degradation because of human settlement, land use and climate changes. A thorough understanding of hydrologic trends and variability associated with the changes is critical for sustainable water resources management and ecosystem restoration in the region. This study examined freshwater inflow (1940-2002) and suspended solids loadings (1978-2001) from three upper Lake Pontchartrain watersheds that contribute to the lake estuary: the Amite, Tickfaw, and Tangipahoa river watersheds. The relationships of freshwater inflow and suspended solids loadings with climate variables and population growth were investigated. Using observed daily discharge, a spatially-distributed hydrologic model (SWAT) was evaluated, and the model then was employed to assess hydrologic responses of the coastal watersheds to potential climate change. The study showed an annual freshwater inflow of 5 km3 yr-1 and average suspended solids inputs of 210,360 tons yr-1 entering Lake Pontchartrain. More than 69% of annual water yield and 66% of suspended solids occurred from December to May and from January to April, respectively. Over 80% of the variation in annual freshwater inflow could be explained by annual precipitation. A significant increase in freshwater inflow was found in the Amite River watershed over the past sixty years, coinciding with both climatic variation and population growth. The hydrologic modeling showed a good agreement between the simulated and observed daily discharge, with a relatively high Nash-Sutcliffe model efficiency (\u3e 0.811) and low mean error (\u3c 5.6%). The simulation further indicated that, unlike upland watersheds, calibration of the surface and channel routing parameters in the SWAT model became most critical for lowland coastal watersheds with gentle relief. The climate change assessment showed a significant influence of precipitation on annual freshwater yield with an increase of 19.3%-40.1% in response to a 10%-20% increase in annual precipitation. Potential air temperature increase would have only a marginal effect on freshwater yield as shown by a 1.4%-2.9% decrease in the annual freshwater yield for a 1.6 oC-3.3 oC increase in temperature. Warming, however, may pose risks of drought during spring and summer in this humid subtropical region

Stabilisation of non-equilibrium melt in a linear polyethylene in the presence of reduced graphene oxide nanoplatelets

In this thesis, investigation on stabilisation of non-equilibrium melt in the presence of high aspect ratio reduced graphene oxide nanosheets (rGON) was carried out. The non-equilibrium melt was prepared by melting disentangled ultrahigh molecular weight polyethylene (UHMWPE) which was synthesised using homogeneous single-site catalytic system. Rheological analyses of the disentangled UHMWPE/rGON nanocomposites prepared by physical mixing conclusively demonstrate the transformation of the melt from non-equilibrium state to equilibrium state was suppressed when the filler was added. The suppression effect on the transformation reached maximum at a certain filler content and the non-equilibrium melt state was retained within the experimental time, indicating the existence of strong filler-chain interaction that hindered the chain thermodynamics. In order to have better understanding of the suppression on the transformation, thermal analysis was performed on the non-equilibrium melts to follow the influence of non-equilibrium polymer melt on crystallisation kinetics of disentangled UHMWPE with and without rGON. The analysis was carried out by means of differential scanning calorimetry (DSC), and the changes in enthalpic relaxation process were found in good agreement with the rheological response of the melts. Thermal analysis showed the presence of two endothermic peaks in a sample of non-equilibrium melt that was left to crystallise under isothermal condition after melting. The high temperature endothermic peak (141.5 °C) was related to melting of crystals obtained on crystallisation from the disentangled domains of the heterogeneous (non-equilibrium) polymer melt, whereas the low melting temperature endothermic peak was related to melting of crystals formed from entangled domains of the melt. It was further found that with increasing the annealing time in melt (160 °C), the enthalpy of the lower melting temperature peak increased at the expense of the higher melting temperature peak, confirming transformation of the non-equilibrium polymer melt to equilibrium melt state. The enthalpic relaxation process as a function of rGON showed that at the specific content of the filler, where the suppression of the transformation reached maximum, the high endothermic peak remained independent of the annealing time of the polymer melt at 160 °C. This observation strengthened the concept that in the presence of the filler, chain dynamics was arrested to an extent that the everlasting non-equilibrium melt state having lower entanglement density was retained facilitating crystal formation having high melting endothermic temperature. This unique property of the nanocomposites provokes potential in facilitating their processability and making high demanding products in more complex dimensions

EKF-based dual synchronization of chaotic colpitts circuit and Chua’s circuit

summary:In this paper, dual synchronization of a hybrid system containing a chaotic Colpitts circuit and a Chua’s circuit, connected by an additive white Gaussian noise (AWGN) channel, is studied via numeric simulations. The extended Kalman filter (EKF) is employed as the response system to achieve the dual synchronization. Two methods are proposed and investigated. The first method treats the combination of a Colpitts circuit and a Chua’s circuit as a higher- dimensional system, while the second method considers the Colpitts circuit and Chua’s circuit separately and utilizes the cross-coupling scheme. The simulation results indicate that the proposed methods can effectively achieve and maintain dual synchronization of the hybrid system through an AWGN channel

Free Vibration Analysis for Shells of Revolution Using an Exact Dynamic Stiffness Method

An exact generalised formulation for the free vibration of shells of revolution with general shaped meridians and arbitrary boundary conditions is introduced. Starting from the basic shell theories, the vibration governing equations are obtained in the Hamilton form, from which dynamic stiffness is computed using the ordinary differential equations solver COLSYS. Natural frequencies and modes are determined by employing the Wittrick-Williams (W-W) algorithm in conjunction with the recursive Newton’s method, thus expanding the applications of the abovementioned techniques from one-dimensional skeletal structures to two-dimensional shells of revolution. A solution for solving the number of clamped-end frequencies J0 in the W-W algorithm is presented for both uniform and nonuniform shell segment members. Based on these theories, a FORTRAN program is written. Numerical examples on circular cylindrical shells, hyperboloidal cooling tower shells, and spherical shells are given, and error analysis is performed. The convergence of the proposed method on J0 is verified, and comparisons with frequencies from existing literature show that the dynamic stiffness method is robust, reliable, and accurate

Stabilité exponentielle des équations des ondes avec amortissement local de Kelvin–Voigt

We consider the stability of wave equations with local viscoelastic damping distributed around the boundary of domain. We show that the energy of the system goes uniformly and exponentially to zero for all initial data of finite energy

The distinct binding properties between avian/human influenza A virus NS1 and Postsynaptic density protein-95 (PSD-95), and inhibition of nitric oxide production

<p>Abstract</p> <p>Background</p> <p>The NS1 protein of influenza A virus is able to bind with many proteins that affect cellular signal transduction and protein synthesis in infected cells. The NS1 protein consists of approximately 230 amino acids and the last 4 amino acids of the NS1 C-terminal form a PDZ binding motif. Postsynaptic Density Protein-95 (PSD-95), which is mainly expressed in neurons, has 3 PDZ domains. We hypothesise that NS1 binds to PSD-95, and this binding is able to affect neuronal function.</p> <p>Result</p> <p>We conducted a yeast two-hybrid analysis, GST-pull down assays and co-immunoprecipitations to detect the interaction between NS1 and PSD-95. The results showed that NS1 of avian influenza virus H5N1 (A/chicken/Guangdong/1/2005) is able to bind to PSD-95, whereas NS1 of human influenza virus H1N1 (A/Shantou/169/2006) is unable to do so. The results also revealed that NS1 of H5N1 significantly reduces the production of nitric oxide (NO) in rat hippocampal neurons.</p> <p>Conclusion</p> <p>In summary, our study indicates that NS1 of influenza A virus can bind with neuronal PSD-95, and the avian H5N1 and human H1N1 influenza A viruses possess distinct binding properties.</p

Few-Shot Character Understanding in Movies as an Assessment to Meta-Learning of Theory-of-Mind

When reading a story, humans can rapidly understand new fictional characters with a few observations, mainly by drawing analogy to fictional and real people they met before in their lives. This reflects the few-shot and meta-learning essence of humans' inference of characters' mental states, i.e., humans' theory-of-mind (ToM), which is largely ignored in existing research. We fill this gap with a novel NLP benchmark, TOM-IN-AMC, the first assessment of models' ability of meta-learning of ToM in a realistic narrative understanding scenario. Our benchmark consists of $\sim$1,000 parsed movie scripts for this purpose, each corresponding to a few-shot character understanding task; and requires models to mimic humans' ability of fast digesting characters with a few starting scenes in a new movie. Our human study verified that humans can solve our problem by inferring characters' mental states based on their previously seen movies; while the state-of-the-art metric-learning and meta-learning approaches adapted to our task lags 30% behind

Induction of cytopathic effect and cytokines in coxsackievirus B3-infected murine astrocytes

BACKGROUND: Coxsackievirus commonly infects children and occasionally causes severe meningitis and/or encephalitis in the newborn. The underlying mechanism(s) behind the central nervous system pathology is poorly defined. METHODS: It is hypothesized that astrocytes may be involved in inflammatory response induced by CVB3 infection. Here we discuss this hypothesis in the context of CVB3 infection and associated inflammatory response in primary mouse astrocytes. RESULTS: The results showed that coxsackievirus receptor (CAR) was distributed homogeneously on the astrocytes, and that CVB3 could infect and replicate in astrocytes, with release of infectious virus particles. CVB3 induced cytopathic effect and production of proinflammatory cytokines IL-1β, TNF-α, IL-6, and chemokine CXCL10 from astrocytes. CONCLUSION: These data suggest that direct astrocyte damage and cytokines induction could be a mechanism of virus-induced meningitis and/or encephalitis