220 research outputs found

    NONTRIVIAL EQUILIBRIUM SOLUTIONS AND GENERAL 2 STABILITY FOR STOCHASTIC EVOLUTION EQUATIONS WITH PANTOGRAPH DELAY AND TEMPERED FRACTIONAL NOISE∗

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    In this paper, we study the full compressible Navier--Stokes system in a bounded domain Ω⊂R3 , where the viscosity and heat conductivity depend on temperature in a power law (θb for some constant b>0 ) of Chapman--Enskog. We obtain the local existence of strong solution to the initial-boundary value problem (IBVP), which is not trivial, especially for the nonisentropic system with vacuum and temperature-dependent viscosity. There is degeneracy caused by vacuum, and there is extremely strong nonlinearity caused by variable coefficients, both of which create great difficulty for the a priori estimates, especially for the second-order estimates. First, in order to obtain closed first-order estimates, we introduce a new variable to reformulate the system into a better form and require the measure of initial vacuum domain to be sufficiently small. Second, with the help of a cut-off and straightening out technique, and the thermo-insulated boundary condition, we establish the time involved estimate for the second-order derivative of temperature, which plays a key role in closing the a priori estimates. Moreover, our local existence result holds for the cases that the viscosity and heat conductivity depend on θ with possibly different power laws (i.e., μ,λ∼θb1 , κ∼θb2 with constants b1,b2∈[0,+∞) )

    The continuity, regularity and polynomial stability of mild solutions for stochastic 2D-Stokes equations with unbounded delay driven by tempered fractional Gaussian noise

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    We consider stochastic 2D-Stokes equations with unbounded delay in fractional power spaces and moments of order p ≥ 2 driven by a tempered fractional Brownian motion (TFBM) Bσ,λ(t) with −1/2 0. First, the global existence and unique ness of mild solutions are established by using a new technical lemma for stochastic integrals with respect to TFBM in the sense of p-th moment. Moreover, based on the relations between the stochastic integrals with respect to TFBM and fractional Browni an motion, we show the continuity of mild solutions in the case of λ → 0, σ ∈ (−1/2, 0) or λ > 0, σ → σ0 ∈ (−1/2, 0). In particular, we obtain p-th moment H¨older regularity in time and p-th polynomial stability of mild solutions. This paper can be regarded as a first step to study the challenging model: stochastic 2D-Navier-Stokes equations with unbounded delay driven by tempered fractional Gaussian noise

    Genomic epidemiology of Vibrio cholerae reveals the regional and global spread of two epidemic non-toxigenic lineages

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    Non-toxigenic Vibrio cholerae isolates have been found associated with diarrheal disease globally, however, the global picture of non-toxigenic infections is largely unknown. Among non-toxigenic V. cholerae, ctxAB negative, tcpA positive (CNTP) isolates have the highest risk of disease. From 2001 to 2012, 71 infectious diarrhea cases were reported in Hangzhou, China, caused by CNTP serogroup O1 isolates. We sequenced 119 V. cholerae genomes isolated from patients, carriers and the environment in Hangzhou between 2001 and 2012, and compared them with 850 publicly available global isolates. We found that CNTP isolates from Hangzhou belonged to two distinctive lineages, named L3b and L9. Both lineages caused disease over a long time period with usually mild or moderate clinical symptoms. Within Hangzhou, the spread route of the L3b lineage was apparently from rural to urban areas, with aquatic food products being the most likely medium. Both lineages had been previously reported as causing local endemic disease in Latin America, but here we show that global spread of them has occurred, with the most likely origin of L3b lineage being in Central Asia. The L3b lineage has spread to China on at least three occasions. Other spread events, including from China to Thailand and to Latin America were also observed. We fill the missing links in the global spread of the two non-toxigenic serogroup O1 V. cholerae lineages that can cause human infection. The results are important for the design of future disease control strategies: surveillance of V. cholerae should not be limited to ctxAB positive strains

    Gene expression analysis on small numbers of invasive cells collected by chemotaxis from primary mammary tumors of the mouse

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    BACKGROUND: cDNA microarrays have the potential to identify the genes involved in invasion and metastasis. However, when used with whole tumor tissue, the results average the expression patterns of different cell types. We have combined chemotaxis-based cell collection of the invasive subpopulation of cells within the primary tumor with array-based gene expression analysis to identify the genes necessary for the process of carcinoma cell invasion. RESULTS: Invasive cells were collected from live primary tumors using microneedles containing chemotactic growth factors to mimic chemotactic signals thought to be present in the primary tumor. When used with mammary tumors of rats and mice, carcinoma cells and macrophages constitute the invasive cell population. Microbeads conjugated with monoclonal anti-CD11b (Mac-1α) antibodies were used to separate macrophages from carcinoma cells. We utilized PCR-based cDNA amplification from small number of cells and compared it to the quality and complexity of conventionally generated cDNA to determine if amplified cDNA could be used with fidelity for array analysis of this cell population. These techniques showed a very high level of correlation indicating that the PCR based amplification technique yields a cDNA population that resembles, with high fidelity, the original template population present in the small number of cells used to prepare the cDNA for use with the chip. CONCLUSIONS: The specific collection of invasive cells from a primary tumor and the analysis of gene expression in these cells are is now possible. By further comparing the gene expression patterns of cells collected by invasion into microneedles with that of carcinoma cells obtained from the whole primary tumor, the blood, and whole metastatic tumors, genes that contribute to the invasive process in carcinoma cells may be identified

    A unidirectional transition from migratory to perivascular macrophage is required for tumor cell intravasation

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    Summary: Tumor-associated macrophages (TAMs) are critical for tumor metastasis. Two TAM subsets support cancer cell intravasation: migratory macrophages guide cancer cells toward blood vessels, where sessile perivascular macrophages assist their entry into the blood. However, little is known about the inter-relationship between these functionally distinct TAMs or their possible inter-conversion. We show that motile, streaming TAMs are newly arrived monocytes, recruited via CCR2 signaling, that then differentiate into the sessile perivascular macrophages. This unidirectional process is regulated by CXCL12 and CXCR4. Cancer cells induce TGF-β-dependent upregulation of CXCR4 in monocytes, while CXCL12 expressed by perivascular fibroblasts attracts these motile TAMs toward the blood vessels, bringing motile cancer cells with them. Once on the blood vessel, the migratory TAMs differentiate into perivascular macrophages, promoting vascular leakiness and intravasation. : Tumor-associated macrophages (TAMs) are essential for metastasis. Arwert et al. show that, following extravasation, monocytes initially become motile TAMs. Tumor-derived TGF-β then induces CXCR4 on TAMs, stimulating them to migrate toward CXCL12-expressing perivascular fibroblasts. Once adjacent to blood vessels, TAMs differentiate into metastasis-assisting perivascular TAMs. Keywords: tumor associated macrophages, TAMs, TGF beta, breast cancer, metastasis, CXCR4, CCR2, TMEM, Men

    Estimation of stress-strength reliability from unit-Burr â…¢ distribution under records data

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    This paper explores estimation of stress-strength reliability based on upper record values. When the strength and stress variables follow unit-Burr â…¢ distributions, a generalized inferential approach is proposed for estimating stress-strength reliability (SSR). Under the common strength and stress parameter case, two types of pivotal quantities are constructed respectively, and then the generalized point and interval estimates for SSR are proposed in consequence, where the associated Monte-Carlo sampling approach is provided for computation. In addition, when strength and stress variables feature unequal model parameters, different generalized point and confidence interval estimates are also established in this regard. Extensive simulation studies are conducted to examine the behavior of proposed methods. Finally, a real-life data example is presented for illustration

    La\u3csub\u3e0.6\u3c/sub\u3eSr\u3csub\u3e1.4\u3c/sub\u3eMnO\u3csub\u3e4+δ\u3c/sub\u3e Layered Perovskite Oxide: Enhanced catalytic Activity for the Oxygen Reduction Reaction

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    Efficient electrocatalysts for the oxygen reduction reaction (ORR) is a critical factor to influence the performance of lithium–oxygen batteries. In this study, La0.6Sr1.4MnO4+δ layered perovskite oxide as a highly active electrocatalyst for the ORR has been prepared, and a carbon-coating layer with thickness \u3c5 nm has been successfully introduced to enhance the electronic conductivity of the as-prepared oxide. XRD, XPS, Raman, SEM and TEM measurements were carried out to characterize the crystalline structure and morphology of these samples. Rotating ring-disk electrode (RRDE) technique has been used to study catalytic activities of the as-prepared catalysts for the ORR in 0.1 M KOH media. RRDE results reveal that carbon-coated La0.6Sr1.4MnO4+δ exhibits better catalytic activity for the ORR. For the carbon-coated La0.6Sr1.4MnO4+δ, the ORR proceeds predominately via a direct four electron process, and a maximum cathodic current density of 6.70 mA cm−2 at 2500 rpm has been obtained, which is close to that of commercial Pt/C electrocatalyst under the same testing conditions

    ENV-607: SURFACTANT-MODIFIED BIOMASS ADSORBENTS FOR ENHANCED REMOVAL OF POLLUTANTS FROM AQUEOUS SOLUTION

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    From the view of economical efficiency and technology sustainability, considerable attention has been recently given to the use of low-cost biomass residues as adsorbents in pollution control. To achieve a desirable adsorptive efficiency, some efforts have also been made to modify biomass adsorbents through appropriate treatments. There is a particular interest in surfactant-assisted biomass surface modification. Although some findings from previous studies are encouraging, knowledge about the adsorption of pollutants onto surfactant-modified biomass is still limited. A number of issues about the characteristics of involved interface transport are poorly understood. The present study therefore aims to examine the adsorption of anionic azo dyes onto surfactant-modified biomass in the solution. Different surfactants are used for modification. The equilibrium and kinetic studies for the adsorption of anionic azo dyes on modified biomass are conducted and the effects of aqueous chemistry characteristics are also evaluated. The results present the potential of modified biomass as suitable adsorbent for the removal of anionic azo dyes from wastewater. It can help understand the migration patterns of organic pollutants at biomass-water interface
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