448 research outputs found

    1-3 Piezocomposite design optimised for high frequency kerfless transducer arrays

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    Piezocomposites that can operate at frequencies above 30 MHz without spurious modes are required in order to develop sufficiently sensitive high frequency arrays for high resolution imaging. However, scaling down of conventional piezocomposite fabrication techniques becomes increasingly difficult as dimensions decrease with increasing frequency. The approach presented here is to use micro-moulded 1-3 piezocomposites and a distribution of piezoelectric segment size and separation. Innovative approaches to composite pattern design, based on a randomized spatial distribution, are presented. Micro-moulding techniques are shown to be suitable for fabricating composites with dimensions required for high frequency composites. Randomized piezocomposite patterns are modeled and are shown to suppress spurious modes

    Turning waves and breakdown for incompressible flows

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    We consider the evolution of an interface generated between two immiscible incompressible and irrotational fluids. Specifically we study the Muskat and water wave problems. We show that starting with a family of initial data given by (\al,f_0(\al)), the interface reaches a regime in finite time in which is no longer a graph. Therefore there exists a time tt^* where the solution of the free boundary problem parameterized as (\al,f(\al,t)) blows-up: \|\da f\|_{L^\infty}(t^*)=\infty. In particular, for the Muskat problem, this result allows us to reach an unstable regime, for which the Rayleigh-Taylor condition changes sign and the solution breaks down.Comment: 15 page

    Lack of uniqueness for weak solutions of the incompressible porous media equation

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    In this work we consider weak solutions of the incompressible 2-D porous media equation. By using the approach of De Lellis-Sz\'ekelyhidi we prove non-uniqueness for solutions in LL^\infty in space and time.Comment: 23 pages, 2 fugure

    Linfadenitis y absceso subcutáneo por Complejo Mycobacterium avium como manifestación de síndrome inflamatorio de reconstitución inmune luego de un segundo esquema de terapia antirretroviral de gran actividad

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    El síndrome inflamatorio de reconstitución inmune (SIRI) es una reacción atípica e inesperada relacionada con el tratamiento antirretroviral de gran actividad (TARGA) en pacientes infectados por el virus de la inmunodeficiencia humana (VIH). El SIRI representa una respuesta inflamatoria frente a un patógeno oportunista (generalmente Mycobacterium tuberculosis, Complejo Mycobacterium avium, citomegalovirus y herpes varicela-zóster) en pacientes que responden a la TARGA con una marcada reducción de la carga viral en plasma y evidencia de una recuperación inmunológica expresada por el incremento de los niveles de linfocitos T CD4+. Presentamos el caso de un paciente con síndrome de inmunodeficiencia adquirida que desarrolló un absceso subcutáneo en muslo derecho y una adenitis supraclavicular izquierda como manifestación de SIRI por Complejo Mycobacterium avium luego del inicio de un segundo esquema de TARGA.Immune reconstitution inflammatory syndrome (IRIS) is an atypical and unexpected reaction related to highly active antiretroviral therapy (HAART) in human immunodeficiency virus (HIV) infected patients. IRIS includes an atypical response to an opportunistic pathogen (generally Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus and herpes varicella-zoster), in patients responding to HAART with a reduction of plasma viral load and evidence of immune restoration based on increase of CD4+ T-cell count. We reported a case of a patient with AIDS which, after a first failure of HAART, developed a subcutaneous abscess and supraclavicular lymphadenitis as an expression of IRIS due to Mycobacterium avium complex after starting a second scheme of HAART

    Alterações na biomassa microbiana do solo em cultivos de mandioca sob diferentes coberturas vegetais.

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    O presente estudo teve como objetivo avaliar o efeito do cultivo da mandioca em plantio direto sob diferentes coberturas vegetais na biomassa microbiana do solo e índices derivados. Tais parâmetros foram avaliados também em sistema sob preparo convencional (aração e gradagem) e sistema natural (mata nativa), para comparação. Os estudos foram conduzidos no Município de Glória de Dourados, MS,num Argissolo vermelho distrófico, de textura arenosabitstream/item/65168/1/BP200421.pd

    Label-free detection of human prostate-specific antigen (hPSA) using film bulk acoustic resonators (FBARs)

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    Label-free detection of cancer biomarkers using low cost biosensors has promising applications in clinical diagnostics. In this work, ZnO-based thin film bulk acoustic wave resonators (FBARs) with resonant frequency of ∼1.5 GHz and mass sensitivity of 0.015 mg/m2 (1.5 ng/cm2) have been fabricated for their deployment as biosensors. Mouse monoclonal antibody, anti-human prostate-specific antigen (Anti-hPSA) has been used to bind human prostate-specific antigen (hPSA), a model cancer used in this study. Ellipsometry was used to characterize and optimise the antibody adsorption and antigen binding on gold surface. It was found that the best amount of antibody at the gold surface for effective antigen binding is around 1 mg/m2, above or below which resulted in the reduced antigen binding due to either the limited binding sites (below 1 mg/m2) or increased steric effect (above 1 mg/m2). The FBAR data were in good agreement with the data obtained from ellipsometry. Antigen binding experiments using FBAR sensors demonstrated that FBARs have the capability to precisely detect antigen binding, thereby making FBARs an attractive low cost alternative to existing cancer diagnostic sensors.This work was supported by the Engineering and Physical Sciences Research Council [grants EP/F062966/1, EP/F063865/1 and EP/F06294X/1], the Royal Society [grant RG120061] and the National Natural Science Foundation of China (NSFC) [grant 61150110485].This is the accepted manuscript version. The final published version of the article is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0925400513011052

    Breakdown of smoothness for the Muskat problem

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    In this paper we show that there exist analytic initial data in the stable regime for the Muskat problem such that the solution turns to the unstable regime and later breaks down i.e. no longer belongs to C4C^4.Comment: 93 pages, 10 figures (6 added

    On the ill/well-posedness and nonlinear instability of the magneto-geostrophic equations

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    We consider an active scalar equation that is motivated by a model for magneto-geostrophic dynamics and the geodynamo. We prove that the non-diffusive equation is ill-posed in the sense of Hadamard in Sobolev spaces. In contrast, the critically diffusive equation is well-posed. In this case we give an example of a steady state that is nonlinearly unstable, and hence produces a dynamo effect in the sense of an exponentially growing magnetic field.Comment: We have modified the definition of Lipschitz well-posedness, in order to allow for a possible loss in regularity of the solution ma

    A maximum principle for the Muskat problem for fluids with different densities

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    We consider the fluid interface problem given by two incompressible fluids with different densities evolving by Darcy's law. This scenario is known as the Muskat problem for fluids with the same viscosities, being in two dimensions mathematically analogous to the two-phase Hele-Shaw cell. We prove in the stable case (the denser fluid is below) a maximum principle for the LL^\infty norm of the free boundary.Comment: 16 page

    Chemical Constituents, Anticancer and Anti-Proliferative Potential of Limonium Species: A Systematic Review

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    Limonium species represent a source of bioactive compounds that have been widely used in folk medicine. This study aimed to synthesize the anticancer and anti-proliferative potential of Limonium species through a systematic review. Searches were performed in the electronic databases PubMed/MEDLINE, Scopus, and Scielo and via a manual search. In vivo or in vitro studies that evaluated the anticancer or anti-proliferative effect of at least one Limonium species were included. In total, 942 studies were identified, with 33 articles read in full and 17 studies included for qualitative synthesis. Of these, 14 (82.35%) refer to in vitro assays, one (5.88%) was in vivo, and two (11.76%) were designed as in vitro and in vivo assays. Different extracts and isolated compounds from Limonium species were evaluated through cytotoxic analysis against various cancer cells lines (especially hepatocellular carcinoma-HepG2; n = 7, 41.18%). Limonium tetragonum was the most evaluated species. The possible cellular mechanism involved in the anticancer activity of some Limonium species included the inhibition of enzymatic activities and expression of matrix metalloproteinases (MMPs), which suggested anti-metastatic effects, anti-melanogenic activity, cell proliferation inhibition pathways, and antioxidant and immunomodulatory effects. The results reinforce the potential of Limonium species as a source for the discovery and development of new potential cytotoxic and anticancer agents. However, further studies and improvements in experimental designs are needed to better demonstrate the mechanism of action of all of these compounds
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