Renormalization group estimates of transport coefficients in the advection of a passive scalar by incompressible turbulence

The advection of a passive scalar by incompressible turbulence is considered using recursive renormalization group procedures in the differential sub grid shell thickness limit. It is shown explicitly that the higher order nonlinearities induced by the recursive renormalization group procedure preserve Galilean invariance. Differential equations, valid for the entire resolvable wave number k range, are determined for the eddy viscosity and eddy diffusivity coefficients, and it is shown that higher order nonlinearities do not contribute as k goes to 0, but have an essential role as k goes to k(sub c) the cutoff wave number separating the resolvable scales from the sub grid scales. The recursive renormalization transport coefficients and the associated eddy Prandtl number are in good agreement with the k-dependent transport coefficients derived from closure theories and experiments

Insulin-like growth factor-I ameliorates demyelination induced by tumor necrosis factor-α in transgenic mice

Our laboratories have reported that TNF-α causes myelin damage and apoptosis of oligodendrocytes and their precursors in vitro and in vivo. We also have reported that IGF-I can protect cultured oligodendrocytes and their precursors from TNF-α-induced damage. In this study, we investigated whether IGF-I can protect oligodendrocytes and myelination from TNF-α-induced damage in vivo by cross-breeding TNF-α transgenic (Tg) mice with IGF-I Tg mice that overexpress IGF-I exclusively in brain. At 8 weeks of age, compared to wildtype (WT) mice, the brain weights of TNF-α Tg mice were decreased by ~20%, while those of IGF-I Tg mice were increased by ~20%. The brain weights of mice that carry both TNF-α and IGF-I transgenes (TNF-α/IGF-I Tg mice) did not differ from WT mice. As judged by histochemical staining and immunostaining, myelin content in the cerebellum of TNF-α/IGF-I Tg mice was similar to that in WT mice and much more than that in TNF-α Tg mice. Consistently, western immunoblot analysis showed that myelin basic protein abundance in the cerebellum of TNF-α/IGF-I Tg mice was double that in TNF-α Tg mice. Compared to WT mice, the number of oligodendrocytes was decreased by ~36% in TNF-α Tg mice, while it was increased in IGF-I Tg mice by ~40%. Oligodendrocyte number in TNF-α/IGF-I Tg mice was almost as twice many as that in TNF-α Tg mice. Furthermore, IGF-I overexpression significantly reduced TNF-α-induced increases in apoptotic cell number, active caspase-3 abundance and degraded MBP. Our results indicate that IGF-I is capable of protecting myelin and oligodendrocytes from TNF-α-induced damage in vivo

Development of a recursion RNG-based turbulence model

Reynolds stress closure models based on the recursion renormalization group theory are developed for the prediction of turbulent separated flows. The proposed model uses a finite wavenumber truncation scheme to account for the spectral distribution of energy. In particular, the model incorporates effects of both local and nonlocal interactions. The nonlocal interactions are shown to yield a contribution identical to that from the epsilon-renormalization group (RNG), while the local interactions introduce higher order dispersive effects. A formal analysis of the model is presented and its ability to accurately predict separated flows is analyzed from a combined theoretical and computational stand point. Turbulent flow past a backward facing step is chosen as a test case and the results obtained based on detailed computations demonstrate that the proposed recursion -RNG model with finite cut-off wavenumber can yield very good predictions for the backstep problem

Energy Prediction Based Intrusion Detection In Wireless Sensor Networks

A challenge in designing wireless sensor networks is to maximize the lifetime of the network with respect to limited resources and energy. These limitations make the network particularly vulnerable to attacks from adversaries. Denial of Service (DOS) is considered a severely damaging attack in monitoring applications when intruders attack the network and force it to lose its power and die early. There are intrusion detection approaches, but they require communications and calculations which waste the network’s limited resources. In this paper, we propose a new intrusion detection model that is suitable for defending against DOS attacks. We use the idea of energy prediction to anticipate the energy consumption of the network in order to detect intruders based on the each individual node’s excessive usage of power. Our approach does not require a lot of communications or calculations between the nodes and the cluster head. It is energy efficient and accurate in detecting intruders. Simulations show that our energy aware intrusion detection approach can effectively detect intruders based on energy consumption rate

Energy Prediction Based Intrusion Detection In Wireless Sensor Networks

A challenge in designing wireless sensor networks is to maximize the lifetime of the network with respect to limited resources and energy. These limitations make the network particularly vulnerable to attacks from adversaries. Denial of Service (DOS) is considered a severely damaging attack in monitoring applications when intruders attack the network and force it to lose its power and die early. There are intrusion detection approaches, but they require communications and calculations which waste the network’s limited resources. In this paper, we propose a new intrusion detection model that is suitable for defending against DOS attacks. We use the idea of energy prediction to anticipate the energy consumption of the network in order to detect intruders based on the each individual node’s excessive usage of power. Our approach does not require a lot of communications or calculations between the nodes and the cluster head. It is energy efficient and accurate in detecting intruders. Simulations show that our energy aware intrusion detection approach can effectively detect intruders based on energy consumption rate

Forecasting stock exchange opening with foreign stock markets: evidence from the NYSE and the SSE

The paper examines the forecasting ability of the U.S. stock performance to predict the direction of the Chinese stock price movement at the opening, and vice verse. It shows that since the recent global financial crisis, stock performance in the NYSE has shown significant forecasting ability on the SSE opening

Renormalization Group (RG) in Turbulence: Historical and Comparative Perspective

The term renormalization and renormalization group are explained by reference to various physical systems. The extension of renormalization group to turbulence is then discussed; first as a comprehensive review and second concentrating on the technical details of a few selected approaches. We conclude with a discussion of the relevance and application of renormalization group to turbulence modelling

Targeted infection of HIV-1 Env expressing cells by HIV(CD4/CXCR4) vectors reveals a potential new rationale for HIV-1 mediated down-modulation of CD4

BACKGROUND: Efficient targeted gene transfer and cell type specific transgene expression are important for the safe and effective expression of transgenes in vivo. Enveloped viral vectors allow insertion of exogenous membrane proteins into their envelopes, which could potentially aid in the targeted transduction of specific cell types. Our goal was to specifically target cells that express the T cell tropic HIV-1 envelope protein (Env) using the highly specific interaction of Env with its cellular receptor (CD4) inserted into the envelope of an HIV-1-based viral vector. RESULTS: To generate HIV-1-based vectors carrying the CD4 molecule in their envelope, the CD4 ectodomain was fused to diverse membrane anchors and inserted together with the HIV-1 coreceptor CXCR4 into the envelopes of HIV-1 vector particles. Independent of the type of CD4 anchor, all chimeric CD4 proteins inserted into HIV-1 vector envelopes and the resultant HIV(CD4/CXCR4) particles were able to selectively confer neomycin resistance to cells expressing the fusogenic T cell tropic HIV-1 Env protein. Unexpectedly, in the absence of Env on the target cells, all vector particles carrying the CD4 ectodomain anchored in their envelope adhered to various cell types without infecting these cells. This cell adhesion was very avid. It was independent of the presence of Env on the target cell, the type of CD4 anchor or the presence of CXCR4 on the particle. In mixed cell populations with defined ratios of Env(+)/Env(- )cells, the targeted transduction of Env(+ )cells by HIV(CD4/CXCR4) particles was diminished in proportion to the number of Env(- )cells. CONCLUSION: Vector diversion caused by a strong, non-selective cell binding of CD4(+)-vector particles effectively prevents the targeted transduction of HIV-1 Env expressing cells in mixed cell populations. This Env-independent cell adhesion severely limits the effective use of targeted HIV(CD4/CXCR4) vectors designed to interfere with HIV-1 replication in vivo. Importantly, the existence of this newly described and remarkably strong CD4-dependent cell adhesion suggests that the multiple viral efforts to reduce CD4 cell surface expression may, in part, be to prevent cell adhesion to non-target cells and thereby to increase the infectivity of viral progeny. Preventing CD4 down-modulation by HIV-1 might be an effective component of a multi-faceted antiviral strategy