1,586 research outputs found

    Data management in project planning and control

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    The paper focuses on the importance of an early engagement of stake-holders in order to manage the project along its entire life cycle. An in-creasing level of uncertainty and complexity tends to generate an increasing level of unpredictability, since it is difficult to anticipate all the possible dynamics, internal and external, affecting a complex project. Improving the forecasting/planning process requires the usage of all the data available to the project team, in particular when facing a high level of uncertainty and complexity. In fact, stakeholders are the main sources of knowledge about the project and their early engagement may significantly increase the amount of knowledge, both explicit and tacit, available. As a consequence, project planning and control may be considered as a participatory process resulting from the interaction of the project team with all the stakeholders involved in the project

    A Bayesian approach to improving estimate to complete

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    The capability to develop a reliable ‘Estimate at Completion’ from the earliest stage of project execution is essential in order to develop a proactive project management. This paper provides a methodology to support the development of the Estimate at Completion in large engineering projects. In order to accomplish this aim, a model to formulate estimates at completion is presented which integrates through a Bayesian approach three knowledge sources: experts’ opinions, data from past projects and the current performance of the ongoing project. The model has been applied to three Oil and Gas projects in order to forecast their final duration and cost. These projects are characterized by a high level of size, uncertainty and complexity representing a challenging test for the model. The results obtained show a higher forecasting accuracy of the Bayesian model compared to the traditional Earned Value Management (EVM) methodology. Moreover, the estimates at completion calculated using the Bayesian model are not point estimates such as those calculated by EVM. In fact, the Bayesian approach leads to a probability density function for the forecasted final cost and duration. Hence, the project manager obtains an indication of the degree of confidence about the expected value forecasted which results in better quality information available for the decision making process

    Anatomically-Informed Multiple Linear Assignment Problems for White Matter Bundle Segmentation

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    Segmenting white matter bundles from human tractograms is a task of interest for several applications. Current methods for bundle segmentation consider either only prior knowledge about the relative anatomical position of a bundle, or only its geometrical properties. Our aim is to improve the results of segmentation by proposing a method that takes into account information about both the underlying anatomy and the geometry of bundles at the same time. To achieve this goal, we extend a state-of-the-art example-based method based on the Linear Assignment Problem (LAP) by including prior anatomical information within the optimization process. The proposed method shows a significant improvement with respect to the original method, in particular on small bundles

    Scattering Amplitudes and Toric Geometry

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    In this paper we provide a first attempt towards a toric geometric interpretation of scattering amplitudes. In recent investigations it has indeed been proposed that the all-loop integrand of planar N=4 SYM can be represented in terms of well defined finite objects called on-shell diagrams drawn on disks. Furthermore it has been shown that the physical information of on-shell diagrams is encoded in the geometry of auxiliary algebraic varieties called the totally non negative Grassmannians. In this new formulation the infinite dimensional symmetry of the theory is manifest and many results, that are quite tricky to obtain in terms of the standard Lagrangian formulation of the theory, are instead manifest. In this paper, elaborating on previous results, we provide another picture of the scattering amplitudes in terms of toric geometry. In particular we describe in detail the toric varieties associated to an on-shell diagram, how the singularities of the amplitudes are encoded in some subspaces of the toric variety, and how this picture maps onto the Grassmannian description. Eventually we discuss the action of cluster transformations on the toric varieties. The hope is to provide an alternative description of the scattering amplitudes that could contribute in the developing of this very interesting field of research.Comment: 58 pages, 25 figures, typos corrected, a reference added, to be published in JHE

    Enforcing Security and Assurance Properties in Cloud Environment

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    International audienceBefore deploying their infrastructure (resources, data, communications, ...) on a Cloud computing platform, companies want to be sure that it will be properly secured. At deployment time, the company provides a security policy describing its security requirements through a set of properties. Once its infrastructure deployed, the company want to be assured that this policy is applied and enforced. But describing and enforcing security properties and getting strong evidences of it is a complex task. To address this issue, in [1], we have proposed a language that can be used to express both security and assurance properties on distributed resources. Then, we have shown how these global properties can be cut into a set of properties to be enforced locally. In this paper, we show how these local properties can be used to automatically configure security mechanisms. Our language is context-based which allows it to be easily adapted to any resource naming systems e.g., Linux and Android (with SELinux) or PostgreSQL. Moreover, by abstracting low-level functionalities (e.g., deny write to a file) through capabilities, our language remains independent from the security mechanisms. These capabilities can then be combined into security and assurance properties in order to provide high-level functionalities, such as confidentiality or integrity. Furthermore, we propose a global architecture that receives these properties and automatically configures the security and assurance mechanisms accordingly. Finally, we express the security and assurance policies of an industrial environment for a commercialized product and show how its security is enforced

    White matter alterations in glaucoma and monocular blindness differ outside the visual system

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    The degree to which glaucoma has effects in the brain beyond the eye and the visual pathways is unclear. To clarify this, we investigated white matter microstructure (WMM) in 37 tracts of patients with glaucoma, monocular blindness, and controls. We used brainlife.io for reproducibility. White matter tracts were subdivided into seven categories ranging from those primarily involved in vision (the visual white matter) to those primarily involved in cognition and motor control. In the vision tracts, WMM was decreased as measured by fractional anisotropy in both glaucoma and monocular blind subjects compared to controls, suggesting neurodegeneration due to reduced sensory inputs. A test-retest approach was used to validate these results. The pattern of results was different in monocular blind subjects, where WMM properties increased outside the visual white matter as compared to controls. This pattern of results suggests that whereas in the monocular blind loss of visual input might promote white matter reorganization outside of the early visual system, such reorganization might be reduced or absent in glaucoma. The results provide indirect evidence that in glaucoma unknown factors might limit the reorganization as seen in other patient groups following visual loss

    Intraarterial Injection of Muscle-Derived Cd34+Sca-1+ Stem Cells Restores Dystrophin in mdx Mice

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    Duchenne muscular dystrophy is a lethal recessive disease characterized by widespread muscle damage throughout the body. This increases the difficulty of cell or gene therapy based on direct injections into muscles. One way to circumvent this obstacle would be to use circulating cells capable of homing to the sites of lesions. Here, we showed that stem cell antigen 1 (Sca-1), CD34 double-positive cells purified from the muscle tissues of newborn mice are multipotent in vitro and can undergo both myogenic and multimyeloid differentiation. These muscle-derived stem cells were isolated from newborn mice expressing the LacZ gene under the control of the muscle-specific desmin or troponin I promoter and injected into arterial circulation of the hindlimb of mdx mice. The ability of these cells to interact and firmly adhere to endothelium in mdx muscles microcirculation was demonstrated by intravital microscopy after an intraarterial injection. Donor Sca-1, CD34 muscle-derived stem cells were able to migrate from the circulation into host muscle tissues. Histochemical analysis showed colocalization of LacZ and dystrophin expression in all muscles of the injected hindlimb in all of five out of five 8-wk-old treated mdx mice. Their participation in the formation of muscle fibers was significantly increased by muscle damage done 48 h after their intraarterial injection, as indicated by the presence of 12% β-galactosidase–positive fibers in muscle cross sections. Normal dystrophin transcripts detected enzymes in the muscles of the hind limb injected intraarterially by the mdx reverse transcription polymerase chain reaction method, which differentiates between normal and mdx message. Our results showed that the muscle-derived stem cells first attach to the capillaries of the muscles and then participate in regeneration after muscle damage

    Thoracic and Lumbar Vertebral Bone Mineral Density Changes in a Natural Occurring Dog Model of Diffuse Idiopathic Skeletal Hyperostosis

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    Ankylosing spinal disorders can be associated with alterations in vertebral bone mineral density (BMD). There is however controversy about vertebral BMD in patients wuse idiopathic skeletal hyperostosis (DISH). DISH in Boxer dogs has been considered a natural occurring disease model for DISH in people. The purpose of this study was to compare vertebral BMD between Boxers with and without DISH. Fifty-nine Boxers with (n=30) or without (n=29) DISH that underwent computed tomography were included. Vertebral BMD was calculated for each thoracic and lumbar vertebra by using an earlier reported and validated protocol. For each vertebral body, a region of interest was drawn on the axial computed tomographic images at three separate locations: immediately inferior to the superior end plate, in the middle of the vertebral body, and superior to the inferior end plate. Values from the three axial slices were averaged to give a mean Hounsfield Unit value for each vertebral body. Univariate statistical analysis was performed to identify factors to be included in a multivariate model. The multivariate model including all dogs demonstrated that vertebral DISH status (Coefficient 24.63; 95% CI 16.07 to 33.19; p <0.001), lumbar vertebrae (Coefficient -17.25; 95% CI -23.42 to -11.09; p < 0.01), and to a lesser extent higher age (Coefficient -0.56; 95% CI -1.07 to -0.05; p = 0.03) were significant predictors for vertebral BMD. When the multivariate model was repeated using only dogs with DISH, vertebral DISH status (Coefficient 20.67; 95% CI, 10.98 to 30.37; p < 0.001) and lumbar anatomical region (Coefficient -38.24; 95% CI, -47.75 to -28.73; p < 0.001) were again predictors for vertebral BMD but age was not. The results of this study indicate that DISH can be associated with decreased vertebral BMD. Further studies are necessary to evaluate the clinical importance and pathophysiology of this finding

    USO DE MEMBRANA AMNIÓTICA HUMANA DESCELULARIZADA EM ANASTOMOSES INTESTINAIS: ESTUDO EM RATOS TRATADOS COM 5-FLUOROURACIL

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    Introduction: currently, the most relevant applications of perinatal derivatives are in wound healing, for example, the use of amniotic membrane (AM) as a biomaterials source for use in different healing processes. The anastomotic healing compromised by antimetabolic drugs, such as 5-fluorouracil (5-FU), is a potential target of AM. Objective: To evaluate the healing effects of the AM use in rats treated with 5-FU at a dose of 20 mg/kg on the 7th postoperative day, regarding the parameters percentage of type I collagen (mature), cell viability, microvascular density and granulation tissue formation. Method: Thirty-two Wistar rats were submitted to colotomy and colorraphy, separated in 4 groups with 8t rats each and received, by 7 days, different treatments intraperitoneally, once daily from the operation day until sacrifice: 1- saline solution (C), 2- 20 mg/kg 5-FU, 3- 20 mg/kg 5-FU and 4- MA, and MA. Results: Tthe treatment with 5-FU (20 mg/kg – 7 days) induced adverse effects in the anastomotic healing process evidenced by the decrease of type I collagen (mature), cell viability, percentage microvascular density, granulation tissue formation (leukocyte-fibrin crust and angio-fibroblastic proliferation). The use of AM, under these conditions, induced an improvement in type I collagen (mature) percentage. Conclusion: The treatment with 5-FU induced adverse effects on the healing anastomotic process, and the use of AM, under these conditions, induced improvement in type I (mature) collagen percentage.Introdução: Atualmente emerge em nosso meio aplicações mais relevantes dos derivados perinatais, por exemplo, a membrana amniótica (MA), como fonte de biomateriais para emprego em diferentes processos cicatriciais. O comprometimento anastomótico por drogas antimetabólicas como o 5-fluorouracil (5-FU) é um potencial alvo da MA. Objetivo: Avaliar os efeitos cicatriciais do uso da MA em ratos tratados com 5-FU na dose de 20 mg/kg ao 7º. dia de evolução pós-operatória quanto aos parâmetros porcentagem de colágeno tipo I (maduro), viabilidade celular, densidade microvascular e formação do tecido de granulação. Método: Utilizaram-se 32 ratos da linhagem Wistar submetidos à colotomia e colorrafia separados em 4 grupos com 8 e receberam diferentes tratamentos diariamente por via intraperitoneal até o dia do sacrifício: Solução fisiológica (C), 20  mg/kg 5-FU, 20 mg/kg 5-FU e MA, MA. Resultados: O tratamento com 20 mg/kg de 5-FU, ao 7º. dia pós-operatório induziu efeitos adversos no processo cicatricial anastomótico evidenciados pela diminuição da porcentagem de colágeno tipo I (maduro), da viabilidade celular, da densidade microvascular, da formação de crosta fibrinoleucocitária e da proliferação angiofibroblástica; o uso da MA nestas condições induziu melhora da porcentagem de colágeno tipo I (maduro). Conclusão: O tratamento com 20 mg/kg de 5-FU, ao 7º. dia pós-operatório induziu efeitos adversos no processo cicatricial anastomótico e o uso da MA nestas condições induziu melhora da porcentagem de colágeno tipo I (maduro)

    HighResMIP versions of EC-Earth: EC-Earth3P and EC-Earth3P-HR - Description, model computational performance and basic validation

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    A new global high-resolution coupled climate model, EC-Earth3P-HR has been developed by the EC-Earth consortium, with a resolution of approximately 40 km for the atmosphere and 0.25° for the ocean, alongside with a standard-resolution version of the model, EC-Earth3P (80 km atmosphere, 1.0 ° ocean). The model forcing and simulations follow the High Resolution Model Intercomparison Project (HighResMIP) protocol. According to this protocol, all simulations are made with both high and standard resolutions. The model has been optimized with respect to scalability, performance, data storage and post-processing. In accordance with the HighResMIP protocol, no specific tuning for the high-resolution version has been applied. Increasing horizontal resolution does not result in a general reduction of biases and overall improvement of the variability, and deteriorating impacts can be detected for specific regions and phenomena such as some Euro-Atlantic weather regimes, whereas others such as the El Niño-Southern Oscillation show a clear improvement in their spatial structure. The omission of specific tuning might be responsible for this. The shortness of the spin-up, as prescribed by the HighResMIP protocol, prevented the model from reaching equilibrium. The trend in the control and historical simulations, however, appeared to be similar, resulting in a warming trend, obtained by subtracting the control from the historical simulation, close to the observational one
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