2,364 research outputs found

    The influence of an initial twisting on tapered beams undergoing large displacements

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    The behaviour of pre-twisted and tapered beams (such as turbine or helicopter blades) is characterized by stress distributions that may be quite different from those of the usual beam theory, yielding couplings among bending, twisting and traction. We propose a physical–mathematical model for tapered beams that accounts for the effects of the pre-twist of the cross-sections along the centre-line. The beam centre-line may undergo large displacements, while its cross-sections see small warping both in- and out of their plane. Supposing infinitesimal strain, a variational approach provides the field equations, which are perturbed in terms of a small geometric ratio and shall be solved numerically in general. However, analytical closed-form solutions exist in some cases, such as for isotropic beams with pre-twisted, bi-tapered elliptic cross-sections; they are presented and compared with the results of nonlinear 3D-FEM simulations

    Crisis, sectoral and geographical factors : financial dynamics of Italian cooperatives

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    Purpose: The purpose of this paper is to analyze the financial structure of Italian cooperatives in the period before and during the crisis (2004-2013), in relation to two discriminating factors. At this end, it focuses on two research questions: What financial dynamics the Italian cooperatives have involved before, during and after the 2008 crisis, that is, in the decade 2004/2013? Are there statistically differences between business sectors and geographic area? Design/methodology/approach: Secondary data on AIDA database have been used. The financial structure is assessed using two ratios: the financial leverage ratio and quick ratio. The final sample consists of 1,446 cooperatives. The trend and exploratory analysis, analysis of variance and Tukey-Kramer post-hoc test have been used. Findings: The financial structure of cooperatives has not been substantially affected by the crisis in any geographic area and business sector, by virtue of resilience of their business model. Moreover, these two factors produce statistically significant differences in the financial structure of cooperatives. Research limitations/implications: The study takes into account only the cooperatives that survived the crisis, so, presumably, the strongest. Moreover, another and more ratios should be considered at the end to have a more complete view on the financial dynamics. Originality/value: The literature on resilience of cooperatives is still not very rich. Moreover, this work analyses and integrates aspects and approaches that are not usually considered together

    Cooperatives and crisis : economic dynamics in Italian context

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    This paper focuses on the situation in Italy with specific reference to cooperatives. It aims to analyse their economic situation - represented by two profitability ratios (ROI, ROE) - during the decade 2004-2013. It aims to tests the impact of crisis, geographical area and belonging business sector. Starting from secondary data on AIDA database (at the end 1,446 cooperatives), the trend analysis and analysis of variance (ANOVA) have been used. The findings show, first of all, that the profitability of cooperatives strongly affected by crisis. Secondly, only the business sector affects the level of profitability. The analysis is interesting because the income has a special meaning in cooperatives: it should, in fact, be added to benefiting members that are accounted for as \u201cpeculiar\u201d management costs

    Beamlike models for the analyses of curved, twisted and tapered horizontal-axis wind turbine (HAWT) blades undergoing large displacements

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    Abstract. Continuous ongoing efforts to better predict the mechanical behaviour of complex beamlike structures, such as wind turbine blades, are motivated by the need to improve their performance and reduce the costs. However, new design approaches and the increasing flexibility of such structures make their aeroelastic modelling ever more challenging. For the structural part of this modelling, the best compromise between computational efficiency and accuracy can be obtained via schematizations based on suitable beamlike elements. This paper addresses the modelling of the mechanical behaviour of beamlike structures which are curved, twisted and tapered in their unstressed state and undergo large displacements, in- and out-of-plane cross-sectional warping, and small strains. A suitable model for the problem at hand is proposed. Analytical and numerical results obtained by its application are presented and compared with results from 3D FEM analyses

    Treatment of Vascular Dementia: The Route of Prevention

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    Vascular dementia (VaD), rather than being considered as a univocal nosological entity, should be regarded as a heterogeneous clinical entity which differs in clinical-pathological phenotype as well as in pathophysiological mechanisms, but shares cerebrovascular disease (CVD), resulting from vascular or circulatory pathology, as the cause of dementia. The aim of this review is to discuss VaD treatment focusing particularly on more prevalent ischemic forms. Due to the fact that there are presently no treatments capable of obtaining considerable results once VaD is clinically established, specific emphasis will be given to the therapeutic strategies aimed at the prevention of CVD risk factors. The therapeutic strategies aimed at slowing the progression of the disease will also be discussed

    Palmitylation of viral membrane glycoproteins takes place after exit from the endoplasmic reticulum

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    Abstract Palmitylation of vesicular stomatitis virus G and Sindbis virus E1 glycoproteins has been studied in relation to the transport from the endoplasmic reticulum (ER) to the Golgi complex. Incubation of infected cells at 15 degrees C prevents the transport of newly synthesized membrane proteins from the ER to the Golgi (Saraste, J., and Kuismanen, E. (1984) Cell 38, 535-549). In these conditions, also palmitylation of G protein and of E1 glycoprotein is blocked. When the transport is restored by increasing the temperature, palmitylation occurs quickly and is followed by the complete trimming of peripheral mannose residues due to mannosidase I (a putative cis-Golgi function). Immunofluorescence analysis showed that the G glycoprotein accumulated at 15 degrees C in structures distinct from both ER and Golgi. These studies suggest that transport from the ER to the cis-Golgi involves intermediate compartments

    A novel CMB polarization likelihood package for large angular scales built from combined WMAP and Planck LFI legacy maps

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    We present a CMB large-scale polarization dataset obtained by combining WMAP Ka, Q and V with Planck 70 GHz maps. We employ the legacy frequency maps released by the WMAP and Planck collaborations and perform our own Galactic foreground mitigation technique, which relies on Planck 353 GHz for polarized dust and on Planck 30 GHz and WMAP K for polarized synchrotron. We derive a single, optimally-noise-weighted, low-residual-foreground map and the accompanying noise covariance matrix. These are shown, through χ2\chi^2 analysis, to be robust over an ample collection of Galactic masks. We use this dataset, along with the Planck legacy Commander temperature solution, to build a pixel-based low-resolution CMB likelihood package, whose robustness we test extensively with the aid of simulations, finding excellent consistency. Using this likelihood package alone, we constrain the optical depth to reionazation τ=0.0690.012+0.011\tau=0.069^{+0.011}_{-0.012} at 68%68\% C.L., on 54\% of the sky. Adding the Planck high-\ell temperature and polarization legacy likelihood, the Planck lensing likelihood and BAO observations we find τ=0.07140.0096+0.0087\tau=0.0714_{-0.0096}^{+0.0087} in a full Λ\LambdaCDM exploration. The latter bounds are slightly less constraining than those obtained employing \Planck\ HFI CMB data for large angle polarization, that only include EE correlations. Our bounds are based on a largely independent dataset that does include also TE correlations. They are generally well compatible with Planck HFI preferring slightly higher values of τ\tau. We make the low-resolution Planck and WMAP joint dataset publicly available along with the accompanying likelihood code.Comment: The WMAP+LFI likelihood module is available on \http://www.fe.infn.it/u/pagano/low_ell_datasets/wmap_lfi_legacy

    Stress response to cadmium and manganese in Paracentrotus lividus developing embryos is mediated by nitric oxide

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    Increasing concentrations of contaminants, often resulting from anthropogenic activities, have been reported to occur in the marine environment and affect marine organisms. Among these, the metal ions cadmium and manganese have been shown to induce developmental delay and abnormalities, mainly reflecting skeleton elongation perturbation, in the sea urchin Paracentrotus lividus, an established model for toxicological studies. Here, we provide evidence that the physiological messenger nitric oxide (NO), formed by l-arginine oxidation by NO synthase (NOS), mediates the stress response induced by cadmium and manganese in sea urchins. When NO levels were lowered by inhibiting NOS, the proportion of abnormal plutei increased. Quantitative expression of a panel of 19 genes involved in stress response, skeletogenesis, detoxification and multidrug efflux processes was followed at different developmental stages and under different conditions: metals alone, metals in the presence of NOS inhibitor, NO donor and NOS inhibitor alone. These data allowed the identification of different classes of genes whose metal-induced transcriptional expression was directly or indirectly mediated by NO. These results open new perspectives on the role of NO as a sensor of different stress agents in sea urchin developing embryos. © 2014 Elsevier B.V

    Comparing Performance of Construction Projects Delivered through Different Delivery Methods

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    When new delivery methods are introduced in public procurement, it is customary to analyze and compare their performance against traditional methods. Many early studies compared performance of different project delivery systems, and often developed decision support tools to help owners follow a structured path in measuring performance and, consequently, choose the most appropriate project delivery method. However, the measurement process adopted by these studies was mostly specific to the dataset to be analyzed. Only rarely, it took into account differences deriving from varying project characteristics, and, therefore was not generalizable. Building upon these studies, this study proposes a general framework for comparing performance of projects delivered through different delivery methods. A discussion of how the framework could also be adapted to every industry sector is included. This work can help owners choose a set of metrics to evaluate and compare the performance of project portfolios delivered with more than one delivery method and different industry secto

    Using CMB data to constrain non-isotropic Planck-scale modifications to Electrodynamics

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    We develop a method to constrain non-isotropic features of Cosmic Microwave Background (CMB) polarization, of a type expected to arise in some models describing quantum gravity effects on light propagation. We describe the expected signatures of this kind of anomalous light propagation on CMB photons, showing that it will produce a non-isotropic birefringence effect, i.e. a rotation of the CMB polarization direction whose observed amount depends in a peculiar way on the observation direction. We also show that the sensitivity levels expected for CMB polarization studies by the \emph{Planck} satellite are sufficient for testing these effects if, as assumed in the quantum-gravity literature, their magnitude is set by the minute Planck length.Comment: 18 pages, 4 figures, 2 table
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