681 research outputs found

    Sound absorption performance of sustainable foam materials: Application of analytical and numerical tools for the optimization of forecasting models

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    Traditional models used to predict acoustic properties of poroelastic materials are usually applied to fibrous layers or polyurethane foams. However, for new materials like complex cellular foams these procedures may not be applied due to the different cell microstructure. To this aim, the sound absorbing properties of novel sustainable foam materials are investigated as a function of the nature and loading of waste powders and their effects on the microstructure and the acoustic properties. The foams are prepared from naturally occurring alginates that are in situ polymerized. The morphology and the acoustic properties of the foam-cells appear linked to the particle size distribution of the starting powder. Determination of the parameters of Johnson\u2013Champoux\u2013Allard acoustic model (tortuosity, viscous characteristic length, thermal characteristic length, porosity and flow resistivity) was performed using five different forecasting methods, including traditional analytical model for fibrous materials as well as inverse procedure. A new procedure for tortuosity computation of foam is proposed and validated. Transfer Matrix Method calculation of the absorption coefficient was performed and compared with the experimental data, in order to assess the validity of the model. Indirect method technique is demonstrated to be dependent on experimental measurement of thermal characteristic length

    VEGF(164)-mediated inflammation is required for pathological, but not physiological, ischemia-induced retinal neovascularization

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    Hypoxia-induced VEGF governs both physiological retinal vascular development and pathological retinal neovascularization. In the current paper, the mechanisms of physiological and pathological neovascularization are compared and contrasted. During pathological neovascularization, both the absolute and relative expression levels for VEGF(164) increased to a greater degree than during physiological neovascularization. Furthermore, extensive leukocyte adhesion was observed at the leading edge of pathological, but not physiological, neovascularization. When a VEGF(164)-specific neutralizing aptamer was administered, it potently suppressed the leukocyte adhesion and pathological neovascularization, whereas it had little or no effect on physiological neovascularization. In parallel experiments, genetically altered VEGF(164)-deficient (VEGF(120/188)) mice exhibited no difference in physiological neovascularization when compared with wild-type (VEGF(+/+)) controls. In contrast, administration of a VEGFk-1/Fc fusion protein, which blocks all VEGF isoforms, led to significant suppression of both pathological and physiological neovascularization. In addition, the targeted inactivation of monocyte lineage cells with clodronate-liposomes led to the suppression of pathological neovascularization. Conversely, the blockade of T lymphocyte-mediated immune responses with an anti-CD2 antibody exacerbated pathological neovascularization. These data highlight important molecular and cellular differences between physiological and pathological retinal neovascularization. During pathological neovascularization, VEGF(164) selectively induces inflammation and cellular immunity. These processes provide positive and negative angiogenic regulation, respectively. Together, new therapeutic approaches for selectively targeting pathological, but not physiological, retinal neovascularization are outlined

    Systems Level Approach Reveals the Correlation of Endoderm Differentiation of Mouse Embryonic Stem Cells with Specific Microstructural Cues of Fibrin Gels.

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    Stem cells receive numerous cues from their associated substrate that help to govern their behaviour. However, identification of influential substrate characteristics poses difficulties because of their complex nature. In this study, we developed an integrated experimental and systems level modelling approach to investigate and identify specific substrate features influencing differentiation of mouse embryonic stem cells (mESCs) on a model fibrous substrate, fibrin. We synthesized a range of fibrin gels by varying fibrinogen and thrombin concentrations, which led to a range of substrate stiffness and microstructure. mESCs were cultured on each of these gels, and characterization of the differentiated cells revealed a strong influence of substrate modulation on gene expression patterning. To identify specific substrate features influencing differentiation, the substrate microstructure was quantified by image analysis and correlated with stem cell gene expression patterns using a statistical model. Significant correlations were observed between differentiation and microstructure features, specifically fibre alignment. Furthermore, this relationship occurred in a lineage-specific manner towards endoderm. This systems level approach allows for identification of specific substrate features from a complex material which are influential to cellular behaviour. Such analysis may be effective in guiding the design of scaffolds with specific properties for tissue engineering applications

    Neurite outgrowth induced by an endothelial cell mitogen isolated from retina.

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    Infrared absorption from Charge Density Waves in magnetic manganites

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    The infrared absorption of charge density waves coupled to a magnetic background is first observed in two manganites La{1-x}Ca{x}MnO{3} with x = 0.5 and x = 0.67. In both cases a BCS-like gap 2 Delta (T), which for x=0.5 follows the hysteretic ferro-antiferromagnetic transition, fully opens at a finite T{0} < T{Neel}, with 2 Delta(T{0})/kT{c} close to 5. These results may also explain the unusual coexistence of charge ordering and ferromagnetism in La{0.5}Ca{0.5}MnO{3}.Comment: File revtex + 3 figs. in epsf. To appear on Phys. Rev. Let

    Long-Term Follow-Up of the Response-Adjusted Therapy for Advanced Hodgkin Lymphoma Trial

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    Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.We analyzed long-term results of the response-adapted trial for adult patients with advanced-stage Hodgkin lymphoma. The aim was to confirm noninferiority of treatment de-escalation by omission of bleomycin from doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) for interim fluorodeoxyglucose positron emission tomography (iPET)-negative patients and assess efficacy and long-term safety for iPET-positive patients who underwent treatment intensification with escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone (BEACOPP/BEACOPP14). The median follow-up is 7.3 years. For all patients, the 7-year progression-free survival (PFS) and overall survival (OS) are 78.2% (95% CI, 75.6 to 80.5) and 91.6% (95% CI, 89.7 to 93.2), respectively. The 1.3% difference in 3-year PFS (95% CI, -3.0 to 4.7) between ABVD and doxorubicin, vinblastine, and dacarbazine (AVD) now falls within the predefined noninferiority margin. Among 172 patients with positive iPET, the 7-year PFS was 65.9% (95% CI, 58.1 to 72.6) and the 7-year OS was 83.2% (95% CI, 76.2 to 88.3). The cumulative incidence of second malignancies at 7 years was 5.5% (95% CI, 4.0 to 7.5) for those receiving ABVD/AVD and 2.5% (95% CI, 0.8 to 7.7) for those escalated to BEACOPP. With extended follow-up, these results confirm noninferiority of treatment de-escalation after a negative iPET. Escalation with BEACOPP for iPET-positive patients is effective and safe, with no increase in second malignancies
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