109 research outputs found

    A fuzzy random forest

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    AbstractWhen individual classifiers are combined appropriately, a statistically significant increase in classification accuracy is usually obtained. Multiple classifier systems are the result of combining several individual classifiers. Following Breiman’s methodology, in this paper a multiple classifier system based on a “forest” of fuzzy decision trees, i.e., a fuzzy random forest, is proposed. This approach combines the robustness of multiple classifier systems, the power of the randomness to increase the diversity of the trees, and the flexibility of fuzzy logic and fuzzy sets for imperfect data management. Various combination methods to obtain the final decision of the multiple classifier system are proposed and compared. Some of them are weighted combination methods which make a weighting of the decisions of the different elements of the multiple classifier system (leaves or trees). A comparative study with several datasets is made to show the efficiency of the proposed multiple classifier system and the various combination methods. The proposed multiple classifier system exhibits a good accuracy classification, comparable to that of the best classifiers when tested with conventional data sets. However, unlike other classifiers, the proposed classifier provides a similar accuracy when tested with imperfect datasets (with missing and fuzzy values) and with datasets with noise

    Inflammatory markers and bone mass in children with overweight/obesity: the role of muscular fitness

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    Objectives To examine which inflammatory markers are associated with bone mass and whether this association varies according to muscular fitness in children with overweight/obesity. Methods Plasma interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α), epidermal growth factor, vascular endothelial growth factor A (VEGF), and C-reactive protein were analyzed in 55 children aged 8–11 years. A muscular fitness score was computed. Bone mineral content (BMC) of the total body-less head (TBLH) and lumbar spine (LS) were assessed using dual-energy x-ray absorptiometry. Results IL-6 (β = −0.136) and VEGF (β = −0.099) were associated with TBLH BMC, while TNF-α (β = −0.345) and IL-1β (β = 0.212) were associated with LS BMC (P < 0.05). The interaction effect of muscular fitness showed a trend in the association of VEGF with TBLH BMC (P = 0.122) and TNF-α with LS BMC (P = 0.057). Stratified analyses by muscular fitness levels showed an inverse association of VEGF with TBLH BMC (β = −0.152) and TNF-α with LS BMC (β = −0.491) in the low-fitness group, while no association was found in the high-fitness group. Conclusion IL-6, VEGF, TNF-α, and IL-1β are significantly associated with bone mass. Higher muscular fitness may attenuate the adverse effect of high VEGF and TNF-α on bone mass

    Primary and secondary scintillation measurements in a Xenon Gas Proportional Scintillation Counter

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    16 páginas, 10 figuras, 1 tabla.-- El PDF es la versión post-print.-- et al.NEXT is a new experiment to search for neutrinoless double beta decay using a 100 kg radio-pure high-pressure gaseous xenon TPC. The detector requires excellent energy resolution, which can be achieved in a Xe TPC with electroluminescence readout. Hamamatsu R8520-06SEL photomultipliers are good candidates for the scintillation readout. The performance of this photomultiplier, used as VUV photosensor in a gas proportional scintillation counter, was investigated. Initial results for the detection of primary and secondary scintillation produced as a result of the interaction of 5.9 keV X-rays in gaseous xenon, at room temperature and at pressures up to 3 bar, are presented. An energy resolution of 8.0% was obtained for secondary scintillation produced by 5.9 keV X-rays. No significant variation of the primary scintillation was observed for different pressures (1, 2 and 3 bar) and for electric fields up to 0.8 V cm-1 torr-1 in the drift region, demonstrating negligible recombination luminescence. A primary scintillation yield of 81 ± 7 photons was obtained for 5.9 keV X-rays, corresponding to a mean energy of 72 ± 6 eV to produce a primary scintillation photon in xenon.This work was supported by FCT (Portugal) and FEDER through project PTDC/FIS/103860/2008. E.D.C. Freitas acknowledges grant SFRH/BD/46711/2008 from FCT. C.M.B. Monteiro acknowledges grant SFRH/BD/25569/2005 from FCT. M. Ball, J.J. Gómez-Cadenas and N. Yahlali acknowledge the Spanish MICINN for the Consolider-Ingenio grants CSD2008-00037 and CSD2007-00042 and the research grants FPA2009-13697-C04-04 and FPA2009-13697-C04-B23/12. D.R. Nygren acknowledges support by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under contract DE-AC02-05CH11231.Peer reviewe

    Las redes sociales rumanas en Coslada : un espacio de encuentro intercultural

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    El presente documento recoge la identificación de las redes sociales existentes en el seno de la población de origen rumano en Coslada y el análisis de los mapas sociales obtenidos tras ese proceso de identificación, para llegar posteriormente a el análisis de los conjuntos de acción que se establecen en relación con la creación de un Espacio de Encuentro Rumano en Coslada, en el marco de la investigación participativa "Espacio de encuentro intercultural: caminando hacia la convivencia en Coslada", 2004-2005.This paper examines the social networks of Rumanian residents in Coslada, showing the building of social maps to describe the community. In the process, we identify several action sets that are useful to design a Rumanian intercultural space in Coslada. This was part of a participative action research called "Espacio de encuentro intercultural: caminando hacia la convivencia en Coslada"

    Investigation of the CRT performance of a PET scanner based in liquid xenon: a Monte Carlo study

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    The measurement of the time of flight of the two 511 keV gammas recorded in coincidence in a PET scanner provides an effective way of reducing the random background and therefore increases the scanner sensitivity, provided that the coincidence resolving time (CRT) of the gammas is sufficiently good. Existing commercial systems based in LYSO crystals, such as the GEMINIS of Philips, reach CRT values of 600 ps (FWHM). In this paper we present a Monte Carlo investigation of the CRT performance of a PET scanner exploiting the scintillating properties of liquid xenon. We find that an excellent CRT of 60 70 ps (depending on the PDE of the sensor) can be obtained if the scanner is instrumented with silicon photomultipliers (SiPMs) sensitive to the ultraviolet light emitted by xenon. Alternatively, a CRT of 120 ps can be obtained instrumenting the scanner with (much cheaper) blue-sensitive SiPMs coated with a suitable wavelength shifter. These results show the excellent time of flight capabilities of a PET device based in liquid xenon.The authors acknowledge support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT, the Ministerio de Economia y Competitividad and FEDER of Spain, the Severo Ochoa Program SEV-2014-0398 and GVA under grant PROMETEO/2016/120; we acknowledge enlightening discussions with J. Varela and C. Lerche.Gómez-Cadenas, JJ.; Benlloch-Rodriguez, JM.; Ferrario, P.; Monrabal, F.; Rodriguez-Samaniego, J.; Toledo Alarcón, JF. (2016). Investigation of the CRT performance of a PET scanner based in liquid xenon: a Monte Carlo study. Journal of Instrumentation. 11(P09011). https://doi.org/10.1088/1748-0221/11/09/P09011S11P0901

    Superbeam studies at CERN

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    A conventional low-energy neutrino beam of great intensity could be produced by the Super Proton Linac at CERN as a first stage of a Neutrino Factory. Water Cherenkov and liquid scintillator detectors are studied as possible candidates for a neutrino oscillation experiment which could improve our current knowledge of the atmospheric parameters Δmatm2, θ23 and measure or severely constrain θ13. It is also shown that a very large water detector could eventually observe leptonic CP violation

    Preconditioning 2D integer data for fast convex hull computations

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    In order to accelerate computing the convex hull on a set of n points, a heuristic procedure is often applied to reduce the number of points to a set of s points, s ? n, which also contains the same hull. We present an algorithm to precondition 2D data with integer coordinates bounded by a box of size p × q before building a 2D convex hull, with three distinct advantages. First, we prove that under the condition min(p, q) ? n the algorithm executes in time within O(n); second, no explicit sorting of data is required; and third, the reduced set of s points forms a simple polygonal chain and thus can be directly pipelined into an O(n) time convex hull algorithm. This paper empirically evaluates and quantifies the speed up gained by preconditioning a set of points by a method based on the proposed algorithm before using common convex hull algorithms to build the final hull. A speedup factor of at least four is consistently found from experiments on various datasets when the condition min(p, q) ? n holds; the smaller the ratio min(p, q)/n is in the dataset, the greater the speedup factor achieved

    An Exploratory Study of Healing Circles as a Strategy to Facilitate Resilience in an Undocumented Community

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    Within the United States, the COVID-19 pandemic highlighted critical inequalities affecting undocumented communities and resulting in particularly heightened stress for members of these communities. In addition to the stress associated with COVID-19, immigrants in the United States were more than ever subjected to a hostile antiimmigrant climate under Trump’s administration. Given this compounded stress, the impact of the pandemic on mental health is likely to be disproportionately experienced by undocumented immigrants. In response, a group of psychologists partnered with a leading immigrant rights advocacy organization and formed a reciprocal collaboration to support undocumented communities. A major focus of the collaboration is to foster learning, supporting members of the immigrant community to contribute to their own well-being and others in the community. Accordingly, the collaborative developed and delivered a web-based mental health education session to the immigrant community and to practitioners serving this population. The session presented the use of healing circles as a strength-based approach to building resilience and also sought feedback regarding specific features of healing circles that can enhance their effectiveness in managing distress. Survey data and qualitative findings from this study show that those who participated in the web-based program perceived the session as validating and informative. Findings also underscored the need for creating safe spaces for community members to be vulnerable about their lived experiences while promoting ownership of their narratives. We discuss practical implications pertaining to the development and facilitation of social support groups for immigrants led by nonspecialist community members trained for this role. Impact Statement We describe a reciprocal collaboration between psychologists and an immigrant-led advocacy organization for the purposes of supporting undocumented immigrants in tailoring culturally congruent therapeutic approaches for fostering resilience as they face multiple stressors due to interlocking crises, such as the COVID-19 pandemic and antiimmigrant policies. The collaboration led to the development and delivery of a web-based session that provided immigrant community members and practitioners with recommendations for facilitating healing circles as a strength-based and culturally responsive approach to fostering peer-led social support during stressful times. Findings highlight the need for creating such safe spaces for community members to be vulnerable about their lived experiences and feel validated

    Using a Floating-Gate MOS Transistor as a Transducer in a MEMS Gas Sensing System

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    Floating-gate MOS transistors have been widely used in diverse analog and digital applications. One of these is as a charge sensitive device in sensors for pH measurement in solutions or using gates with metals like Pd or Pt for hydrogen sensing. Efforts are being made to monolithically integrate sensors together with controlling and signal processing electronics using standard technologies. This can be achieved with the demonstrated compatibility between available CMOS technology and MEMS technology. In this paper an in-depth analysis is done regarding the reliability of floating-gate MOS transistors when charge produced by a chemical reaction between metallic oxide thin films with either reducing or oxidizing gases is present. These chemical reactions need temperatures around 200 °C or higher to take place, so thermal insulation of the sensing area must be assured for appropriate operation of the electronics at room temperature. The operation principle of the proposal here presented is confirmed by connecting the gate of a conventional MOS transistor in series with a Fe2O3 layer. It is shown that an electrochemical potential is present on the ferrite layer when reacting with propane

    A Measurement of B Meson Production and Lifetime Using D`− Events in Z0 Decays

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    A study of B meson decays into D l- X final states is presented. In these events, neutral and charged D mesons originate predominantly from B+ and B0 decays, respectively. The dilution of this correlation due to D** production has been taken into account. From 263700 hadronic Z0 decays collected in 1991 with the DELPHI detector at the LEP collider, 92 D0 --> K- pi+, 35 D+ --> K- pi+ pi+ and 61 D*+ --> D0 pi+ followed by D0 --> K- pi+ or D0 --> K- pi+ pi+ pi-, are found with an associated lepton of the same charge as the kaon. From the D0 l- and D*+ l-, the probability f(d) that a b quark hadronizes into a B- (or B0BAR),meson is found to be 0.44 +/-0.08 +/-0.09, corresponding to a total (B(s) + LAMBDA(b)) hadronization fraction of 0.12(-0.12)+0.24 .By reconstructing the energy of each B meson, the b quark fragmentation is directly measured for the first time. The mean value of the B meson energy fraction is: [X(E)(B)] = 0.695+/-0.015(stat.)+/-0.029(syst.) Reconstructing D-lepton vertices, the following B life-times are measured: tau(B) = 1.27(-0.18)+0.22(stat.)+/-0.15(syst.) ps, where bBAR --> D0 l- X, tau(B) = 1.18(-0.27)+0.39(stat.)+/-0.15(syst.) ps, where BBAR --> D+ l- X, T(B) = 1.19(-0.19)+0.25(stat.)+/-0.15(syst.) ps where BBAR --> D*+ l- X, and an average tau(B) = 1.23(-0.13)+0.14(stat.)+/-0.15(syst.) ps is found. Allowing for decays into D** l- vBAR, the B+ and B0 lifetimes are: tau(B+)= 1.30(0.29)+0.33(stat.)+/-0.15(syst. exp.) +/-0.05(syst. D**) ps, tau(B0)= 1.17(-0.23)+0.29(stat.)+/-0.15(syst. exp.) +/-0.05 (syst. D**) ps, tau(B+)/tau(B0) = 1.11(0.39)+0.51(stat.)+/-0.05(syst. exp.) +/-0.10(syst. D**) ps
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