5,955 research outputs found

    Mixing in convective thermal fluxes in unsteady nonhomogeneous flows generating complex three dimensional vorticity patterns

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    Diffusion and scaling of the velocity and vorticity in a thermoelectric driven heating and cooling experimental device is presented in order to map the different patterns and transitions between two and three dimensional convection in an enclosure with complex driven flows. The size of the water tank is of 0.2 x 0.2 x 0.1 m and the heat sources or sinks can be regulated both in power and sign [1-3]. The thermal convective driven flows are generated by means of Peltier effects in 4 wall extended positions of 0.05 x 0.05 cm each. The parameter range of convective cell array varies strongly with the Topology of the boundary conditions. Side heat and momentum fluxes are a function of Rayleigh, Peclet and Nusselt numbers, [4-6] Visualizations are performed by PIV, Particle tracking and shadowgraph. The structure of the flow is shown by setting up a convective flow generated by buoyant heat fluxes. The experiments described here investigate high Prandtl number mixing using brine and fresh water in order to form a density interface and low Prandtl number mixing with temperature gradients. The evolution of the mixing fronts are compared and the topological characteristics of the merging of the convective structures are examined for different configurations. Based on two dimensional Vorticity spectral analysis, new techniques can be very useful to determine the evolution of scales considering the multi-fractal structure of the convective flows.Peer ReviewedPostprint (published version

    A near-infrared spectroscopy study on thermal transitions of PMMA and PMMA/SiO2 nanocomposites

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    In this work infrared spectroscopy in the near infrared (NIR) range is used to study the dynamics of polymethylmethacrylate (PMMA) as a pure polymer and when it is modified with silica nanoparticles. Different ways of analyzing FT-NIR spectra were explored taking the temperature as the variable of the systems: i) bands shifts in terms of the first moment of the wavenumber; ii) bands shifts in terms of an absorbance ratio method and iii) absorbance variations in terms of the integrated absorbance. The spectroscopic analysis allowed to study thermal transitions in PMMA and PMMA based nanocomposites. In particular the method based on the use of an absorbance ratio is the most sensible to analyze the thermal transitions. All bands considered could be used to detect thermal transitions reflecting how the vibrations of the groups CH2; CH3 and CÂĽO are affected by changes in the free volume of the PMMA. It seems that the PMMA dynamics is more driven by the lateral groups than the backbone of the polymer. The presence of silica nanoparticles, at least when 1% by weight is used, restrains the PMMA motion increasing the relaxation temperatures that can be associated with the glass transitions

    Analysis of MBLOCA and LBLOCA success criteria in VVER-1000/V320 reactors. New proposals for PSA Level 1

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    The specific configuration of the safety systems in VVER-1000/V320 reactors allows a comprehensive study of the Loss of Coolant Accident (LOCA). In the present paper, a verification of the success criteria of the event trees headers for the medium and large break LOCA sequences is conducted. A detailed TRACEV5P5 thermal-hydraulic model of the reactor has been developed, including all safety systems. When analyzing the results of all sequences, some conservatism is observed in certain specific configurations as the success criterion of some headers is not consistent with the classic PSA level 1. Therefore, new proposals for the LOCA event trees are performed based on a reconfiguration of LOCA break ranges and the use of the expanded event trees approach

    Bayesian variable selection and survival modeling: assessing the Most important comorbidities that impact lung and colorectal cancer survival in Spain

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    ancer survival represents one of the main indicators of interest in cancer epidemiology. However, the survival of cancer patients can be affected by several factors, such as comorbidities, that may interact with the cancer biology. Moreover, it is interesting to understand how different cancer sites and tumour stages are affected by different comorbidities. Identifying the comorbidities that affect cancer survival is thus of interest as it can be used to identify factors driving the survival of cancer patients. This information can also be used to identify vulnerable groups of patients with comorbidities that may lead to worst prognosis of cancer. We address these questions and propose a principled selection and evaluation of the effect of comorbidities on the overall survival of cancer patients. In the first step, we apply a Bayesian variable selection method that can be used to identify the comorbidities that predict overall survival. In the second step, we build a general Bayesian survival model that accounts for time-varying effects. In the third step, we derive several posterior predictive measures to quantify the effect of individual comorbidities on the population overall survival. We present applications to data on lung and colorectal cancers from two Spanish population-based cancer registries. The proposed methodology is implemented with a combination of the R-packages mombf and rstan. We provide the code for reproducibility at https://github.com/migariane/BayesVarImpComorbiCancer

    Design of Low-Cost Vehicle Roll Angle Estimator Based on Kalman Filters and an IoT Architecture

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    In recent years, there have been many advances in vehicle technologies based on the efficient use of real-time data provided by embedded sensors. Some of these technologies can help you avoid or reduce the severity of a crash such as the Roll Stability Control (RSC) systems for commercial vehicles. In RSC, several critical variables to consider such as sideslip or roll angle canonly be directly measured using expensive equipment. These kind of devices would increase the priceof commercial vehicles. Nevertheless, sideslip or roll angle or values can be estimated using MEMSsensors in combination with data fusion algorithms. The objectives stated for this research workconsist of integrating roll angle estimators based on Linear and Unscented Kalman filters to evaluatethe precision of the results obtained and determining the fulfillment of the hard real-time processing constraints to embed this kind of estimators in IoT architectures based on low-cost equipment able to be deployed in commercial vehicles. An experimental testbed composed of a van with two setsof low-cost kits was set up, the first one including a Raspberry Pi 3 Model B, and the other having an Intel Edison System on Chip. This experimental environment was tested under different conditions for comparison. The results obtained from low-cost experimental kits, based on IoT architecturesand including estimators based on Kalman filters, provide accurate roll angle estimation. Also, these results show that the processing time to get the data and execute the estimations based on Kalman Filters fulfill hard real time constraints.This work has been supported by Project funded by the Spanish Government, Spanish Ministry of Economy and Competitiveness (Intelligent system of prevention of vuelco in commercial vehicles based on FPGAS [TRA2013-48030-C2-1-R]

    A web-oriented application for 3D craniofacial reconstruction in forensic medicine

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    uman identification from a skull is a critical process in legal and forensic medicine, especially when no other means are available. Traditional clay-based methods attempt to generate the human face, in order to identify the corresponding person. However, these reconstructions lack of objectivity and consistence, since they depend on the practitioner. Moreover, the results of the reconstruction cannot be easily distributed and consulted from everywhere. This paper presents a completely objective 3D craniofacial reconstruction automatic system that provides access to the reconstructions through the Web. The software tool is able to generate an individual facial reconstruction from the 3D image of the skull and three parameters: age, gender and Body Mass Index (BMI) of the individual. Afterwards, the reconstruction can be manually modified by changing any tissue depth value. Both entry data and the reconstructions generated by the tool will be stored in a database, so they are accessible from the Internet. Conclusions of this paper yield promising results: on the one hand, the scientific and technical feasibility of the presented craniofacial reconstruction technique is proved, and also its preference against traditional craniofacial reconstruction methods. On the other hand, this procedure means a remarkable advantage from the point of view of access, visualization and sharing of information, and also in terms of security, since it includes an authentication protocol

    Computerized Three-Dimmensional Craniofacial Reconstruction from Skulls Based on Landmarks.

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    Human identification from a skull is a critical process in legal and forensic medicine, specially when no other means are available. Traditional clay-based methods attempt to generate the human face, in order to identify the corresponding person. However, these reconstructions lack of objectivity and consistence, since they depend on the practitioner. Current computerized techniques are based on facial models, which introduce undesired facial features when the final reconstruction is built. This paper presents an objective 3D craniofacial reconstruction technique, implemented in a graphic application, without using any facial template. The only information required by the software tool is the 3D image of the target skull and three parameters: age, gender and Body Mass Index (BMI) of the individual. Complexity is minimized, since the application database only consists of the anthropological information provided by soft tissue depth values in a set of points of the skull

    Convective thermal fluxes in unsteady non-homogeneous flows

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    In this paper we describe a novel experimental apparatus consisting of a thermoelectric driven heating and cooling device that could be used in didactic laboratories and research. Is possible to model common environmental flows by means of convective cooling and/or heating. We describe here a four cell device, in a 3D enclosure, but furthermore, it is possible to generate a convective flow of complex profiles using an array of thermoelectric devices (Peltier/Seebeck cells) controlled by a thermal proportional-integral-derivative controller generating a multisource buoyant flux. When convective heating and cooling takes place the combination of internal waves and buoyant turbulence is much more complicated if the Rayleigh and Reynolds numbers are high in order to study entrainment and mixing. The experiments made by our thermoelectric driven device could be used to analyze complex mixing, in either low or high Prandtl numbers, using scalar or heat transport in different liquids. From the varied experiments carried out with our device, we can compute and visualize the fields of velocity, vorticity, density and their gradients, here just a few configurations and the corresponding flows will be shown.This work was partially supported by the company BEROTZA S.L. under Grant No. UPC-BEROTZA-2014-0880 We would also like to thank FLUMEN-UPC and ERCOFTAC and the PELNoHT for travel support for J.T.. Technology Transfer Centre of Technical University of Catalonia (CTT-UPC) grant supported the implementation and analyses of the experiments. Sincere gratitude is extended to Dr. H. Takeda and Masao Kuramitsu from Hokaido Univ.Peer ReviewedPostprint (author's final draft

    A phase II trial of weekly nab-paclitaxel for progressive and symptomatic desmoid tumors

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    Desmoid tumors; Phase II trial; PaclitaxelTumores desmoides; Ensayo de fase II; PaclitaxelTumors desmoides; Assaig de fase II; PaclitaxelDesmoid fibromatosis (DF) are mesenchymal neoplasms, with potential aggressive course and relevant clinical impact. New systemic therapy modalities are needed in this symptomatic/progressive population. In this multicenter, phase II trial (NCT03275818), patients with symptomatic/progressing DF received three cycles of weekly nab-paclitaxel. Brief pain inventory short form (BPI-SF) was collected at baseline and in every visit. MRI was performed every 3 months. Primary composite endpoint was RECIST 1.1 overall response rate (ORR) and/or clinical response (improvement ≥ 2 points in BPI-SF). If 40% of patients achieved clinical/radiological response, further investigation would be warranted. Toxicity, progression-free survival (PFS), pattern of response and its correlation with clinical best response and BPI, variation of physical function, and analgesic consumption were secondary endpoints. The translational research reported was not a pre-specified secondary outcome. Forty eligible patients started therapy, being 35 radiologically and clinically evaluable. The study achieved its primary endpoint, as 7(20%) patients obtained RECIST partial response, whereas 31(89%) experienced pain reduction of ≥2 points in BPI-SF worst pain. Therapy was well tolerated. With a median follow-up of 30(14–44) months, median 12 and 24-months PFS rates were 91%(CI 95%, 82–100) and 84%(CI 95%, 71–97). For clinical progression, 12 and 24-months PFS rates were 85% (CI 95%, 73–97) and 74% (CI 95%, 58–90) respectively. Short course of nab-paclitaxel is active, safe and achieves quick and durable responses in progressing/symptomatic DF patients.The authors would like to thank the Spanish group for Research on Sarcomas (GEIS) for supporting the study and BMS/ Celgene (study ID AX-CL-GEIS-007345) for providing drug supply. The sponsor (GEIS) has been in charge of study design, data collection, analysis and manuscript writing. The authors also thank the donors and the University Hospital Virgen del Rocío for participating in patient recruitment. The authors would like to thank Araceli Rodriguez Morales and Gabriela Golab for Data Management. David S. Moura is recipient of a Sara Borrell postdoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (CD20/00155). The authors would also like to thank SELNET project. SELNET has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 825806
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