3,658 research outputs found

    Economic crisis effects on SME dynamic capabilities

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    Based on dynamic capabilities theoretical framework, this research sought to understand the implications of the recent economic crisis on the capability of developing new products by Portuguese SMEs. Specifically, we assessed how this capability was affected by variables such as entrepreneurship, innovation capacity, the knowledge accumulation, and partnerships. The hypotheses were tested using two samples, one before the crisis, with 180 and another with 105 respondents, applied during the crisis (2012). Results reveal that during the crisis SMEs were more objective and effective in the use of their resources and capabilities. In particular, was found that during the crisis the entrepreneurship, innovation capacity, accumulation of knowledge and partnerships, have an impact on the capability of developing new products. Before the crisis, only entrepreneurship and knowledge accumulation have affected this capability.info:eu-repo/semantics/acceptedVersio

    Photorefraction images analysis through neural networks

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    The importance of an early evaluation of infants’ visual system condition is long time recognized. Non-corrected visual disorders may lead to major vision and developmental non-reversible limitations in the future. Among the objective methods of refraction, photorefractive techniques are specifically designed for screening young children. Over the years a number of photorefraction systems with different grades of complexity and automation were developed. A critical problem that one needs to deal with in any approach to these systems is the interpretation and classification of the photorefraction images. In digital photorefraction conventional image processing operators and Fourier techniques were currently used. In this communication we will report on the use of Neural Networks for automated classification of digital photorefraction images.Secretariado Nacional para a Reabilitação - programa CITE III

    Automated algorithm for carotid lumen segmentation and 3D reconstruction in B-mode images

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    The B-mode image system is one of the most popular systems used in the medical area; however it imposes several difficulties in the image segmentation process due to low contrast and noise. Although these difficulties, this image mode is often used in the study and diagnosis of the carotid artery diseases.In this paper, it is described the a novel automated algorithm for carotid lumen segmentation and 3-D reconstruction in B- mode images

    Characterisation of S185 steel under monotonic loading by a feature tracking method

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    In this work, the mechanical behaviour of S185 steel under monotonic loading was characterised by using an image feature-based tracking method. Tensile tests on three types of cylindrical specimens were carried out, in particularly using smooth and notched specimens. Target features were painted on the specimen surfaces and tracked in images sequences in order to estimate the experimental load-displacement curves. Finite element analyses of the non-linear behaviour of steel components were also performed, being the parameters of the different plasticity employed determined by fitting the experimental and numerical data

    Computational Diagnosis of Skin Lesions from Dermoscopic Images using Combined Features

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    There has been an alarming increase in the number of skin cancer cases worldwide in recent years, which has raised interest in computational systems for automatic diagnosis to assist early diagnosis and prevention. Feature extraction to describe skin lesions is a challenging research area due to the difficulty in selecting meaningful features. The main objective of this work is to find the best combination of features, based on shape properties, colour variation and texture analysis, to be extracted using various feature extraction methods. Several colour spaces are used for the extraction of both colour- and texture-related features. Different categories of classifiers were adopted to evaluate the proposed feature extraction step, and several feature selection algorithms were compared for the classification of skin lesions. The developed skin lesion computational diagnosis system was applied to a set of 1104 dermoscopic images using a cross-validation procedure. The best results were obtained by an optimum-path forest classifier with very promising results. The proposed system achieved an accuracy of 92.3%, sensitivity of 87.5% and specificity of 97.1% when the full set of features was used. Furthermore, it achieved an accuracy of 91.6%, sensitivity of 87% and specificity of 96.2%, when 50 features were selected using a correlation-based feature selection algorithm

    Classification of calcified regions in atherosclerotic lesions of the carotid artery in computed tomography angiography images

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    The identification of atherosclerotic plaque components, extraction and analysis of their morphology represent an important role towards the prediction of cardiovascular events. In this article, the classification of regions representing calcified components in computed tomography angiography (CTA) images of the carotid artery is tackled. The proposed classification model has two main steps: the classification per pixel and the classification per region. Features extracted from each pixel inside the carotid artery are submitted to four classifiers in order to determine the correct class, i.e. calcification or non-calcification. Then, geometrical and intensity features extracted from each candidate region resulting from the pixel classification step are submitted to the classification per region in order to determine the correct regions of calcified components. In order to evaluate the classification accuracy, the results of the proposed classification model were compared against ground truths of calcifications obtained from micro-computed tomography images of excised atherosclerotic plaques that were registered with in vivo CTA images. The average values of the Spearman correlation coefficient obtained by the linear discriminant classifier were higher than 0.80 for the relative volume of the calcified components. Moreover, the average values of the absolute error between the relative volumes of the classified calcium regions and the ones calculated from the corresponding ground truths were lower than 3%. The new classification model seems to be adequate as an auxiliary diagnostic tool for identifying calcifications and allowing their morphology assessment. (c) 2019, Springer-Verlag London Ltd., part of Springer Nature

    Hypericum androsaemum water extract inhibits proliferation in human colorectal cancer cells through effects on MAP kinases and PI3K/Akt pathway

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    MAP kinase and PI3K/Akt signalling pathways are commonly altered in colorectal carcinoma (CRC) leading to tumor growth due to increased cell proliferation and inhibition of apoptosis. Several species of the genus Hypericum are used in Portugal to prepare herbal teas to which digestive tract effects are attributed. In the present study, the antiproliferative and proapoptotic effects of the water extracts of H. androsaemum (HA) and H. perforatum (HP) were investigated in two human colon carcinoma-derived cell lines, HCT15 and CO115, which harbour activating mutations of KRAS and BRAF, respectively. Contrarily to HP, HA significantly inhibited cell proliferation and induced apoptosis in both cell lines. HA decreased BRAF and phospho-ERK expressions in CO115, but not in HCT15. HA also decreased Akt phosphorylation in CO115 and induced p38 and JNK in both cell lines. HA induced cell cycle arrest at S and G2/M phases as well as caspase-dependent apoptosis in both cell lines. Chlorogenic acid (CA), the main phenolic compound present in the HA extract and less represented in the HP water extract, did, however, not show any of those effects when used individually. In conclusion, water extract of HA, but not of HP, controlled CRC proliferation and specifically acted on mutant and not wild-type BRAF. The effect of HA was, however, not due to CA alone.CPRX was supported by the Foundation for Science and Technology (FCT), Portugal, through the grant SFRH/BD/27524/2006 and the work was supported by the FCT research grants PTDC/AGR-AAM/70418/2006 (HypericumBiotech) and PEst-C/BIA/UI4050/2011. All projects are co-funded by the program COMPETE from QREN with co-participation from the European Community fund FEDER

    Salvia fruticosa, salvia officinalis and rosmarinic acid induce apoptosis and inhibit proliferation of human colorectal cell lines: the role in MAPK/ERK pathway

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    Epidemiologic studies have shown that nutrition is a key factor in modulating sporadic colorectal carcinoma (CRC) risk. Aromatic plants of the genus Salvia (sage) have been attributed many medicinal properties, which include anticancer activity. In the present study, the antiproliferative and pro-apoptotic effects of water extracts of Salvia fruticosa (SF) and Salvia officinalis (SO) and of their main phenolic compound rosmarinic acid (RA) were evaluated in two human colon carcinoma-derived cell lines, HCT15 and CO115, which have different mutations in the MAPK/ERK and PI3K/Akt signalling pathways. These pathways are commonly altered in CRC leading to increased proliferation and inhibition of apoptosis. Our results show that SF, SO and RA induce apoptosis in both cell lines, whereas cell proliferation was inhibited by the two sage extracts only in HCT15. SO, SF and RA inhibited ERK phosphorylation in HCT15 and had no effects on Akt phosphorylation in CO115 cells. The activity of sage extracts seems to be due, at least in part, to the inhibition of MAPK/ERK pathway.POCI/AGR/62040/2004. CPRX and CFLSFRH/BD/27524/2006 and SFRH/BPD/26316/2006Foundation for Science and Technology (FCT

    On the cost of database clusters reconfiguration

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    Database clusters based on share-nothing replication techniques are currently widely accepted as a practical solution to scalability and availability of the data tier. A key issue when planning such systems is the ability to meet service level agreements when load spikes occur or cluster nodes fail. This translates into the ability to provision and deploy additional nodes. Many current research efforts focus on designing autonomic controllers to perform such reconfiguration, tuned to quickly react to system changes and spawn new replicas based on resource usage and performance measurements. In contrast, we are concerned about the inherent impact of deploying an additional node to an online cluster, considering both the time required to finish such an action as well as the impact on resource usage and performance of the cluster as a whole. If noticeable, such impact hinders the practicability of self-management techniques, since it adds an additional dimension that has to be accounted for. Our approach is to systematically benchmark a number of different reconfiguration scenarios to assess the cost of bringing a new replica online. We consider factors such as: workload characteristics, incremental and parallel recovery, flow control and outdatedness of the recovering replica. As a result, we show that research should be refocused from optimizing the capture and transmition of changes to applying them, which in a realistic setting dominates the cost of the recovery operation.Work supported by the Spanish Government under research grant TIN2006-14738-C02-02
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