2,946 research outputs found

    Influence of incorporation of fluoroalkyl methacrylates on roughness and flexural strength of a denture base acrylic resin

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    Fluorinated denture base acrylic resins can present more stable physical properties when compared with conventional polymers. This study evaluated the incorporation of a fluoroalkyl methacrylate (FMA) mixture in a denture base material and its effect on roughness and flexural strength. A swelling behavior assessment of acrylic resin specimens (n=3, per substance) after 12 h of FMA or methyl methacrylate (MMA) immersion was conducted to determine the solvent properties. Rectangular specimens (n=30) were allocated to three groups, according to the concentration of FMA substituted into the monomer component of a heat-polymerized acrylic resin (Lucitone 550), as follows: 0% (control), 10% and 20% (v/v). Acrylic resin mixed with concentrations of 25% or more did not reach the dough stage and was not viable. The surface roughness and flexural strength of the specimens were tested. Variables were analyzed by ANOVA and Tukey's test (a=0.05). Immersion in FMA produced negligible swelling, and MMA produced obvious swelling and dissolution of the specimens. Surface roughness at concentrations of 0%, 10% and 20% were: 0.25 ± 0.04, 0.24 ± 0.04, 0.22 ± 0.03 mm (F=1.78; p=0.189, not significant). Significant differences were found for flexural strength (F=15.92; p<0.001) and modulus of elasticity (F=7.67; p=0.002), with the following results: 96 ± 6, 82 ± 5, 84 ± 6 MPa, and 2,717 ± 79, 2,558 ± 128, 2574 ± 87 MPa, respectively. The solvent properties of FMA against acrylic resin are weak, which would explain why concentrations over 20% were not viable. Surface changes were not detected after the incorporation of FMA in the denture base acrylic resin tested. The addition of FMA into denture base resin may lower the flexural strength and modulus of elasticity, regardless of the tested concentration

    Coupled effects of climate teleconnections on drought, Santa Ana winds and wildfires in southern California

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    Projections of future climate change impacts suggest an increase of wildfire activity in Mediterranean ecosystems, such as southern California. This region is a wildfire hotspot and fire managers are under increasingly high pressures to minimize socio-economic impacts. In this context, predictions of high-risk fire seasons are essential to achieve adequate preventive planning. Regional-scale weather patterns and climatic teleconnections play a key role in modulating fire-conducive conditions across the globe, yet an analysis of the coupled effects of these systems onto the spread of large wildfires is lacking for the region. We analyzed seven decades (1953–2018) of documentary wildfire records from southern California to assess the linkages between weather patterns and large-scale climate modes using various statistical techniques, including Redundancy Analysis, Superposed Epoch Analysis and Wavelet Coherence. We found that high area burned is significantly associated with the occurrence of adverse weather patterns, such as severe droughts and Santa Ana winds. Further, we document how these fire-promoting events are mediated by climate teleconnections, particularly by the coupled effects of El Niño Southern Oscillation and Atlantic Multidecadal Oscillation

    Tweaking synchronization by connectivity modifications

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    ACKNOWLEDGMENTS The authors wish to thank the Nesin Foundation for an amazing working group activity in Nesin Math Village, and we wish to thank Tiago Pereira for fruitful discussions. P.S. and J.K. acknowledge gratefully the support of BMBF, CoNDyNet, FK. 03SF0472A. T.P. acknowledges FAPESP (No. 2012/22160-7 and No. 2015/02486-3) and IRTG 1740. D.E. acknowledge support by the Leibniz Association (WGL) under Grant No. SAW-2013-IZW-2542.Peer reviewedPublisher PD

    Explaining the Higgs Decays at the LHC with an Extended Electroweak Model

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    We show that the recent discovery of a new boson at the LHC, which we assume to be a Higgs boson, and the observed enhancement in its diphoton decays compared to the SM prediction, can be explained by a new doublet of charged vector bosons from an extended electroweak gauge sector model with SU(3)_C\otimesSU(3)_L\otimesU(1)_X symmetry. Our results show a good agreement between our theoretical expected sensitivity to a 126--125 GeV Higgs boson and the experimental significance observed in the diphoton channel at the 8 TeV LHC. Effects of an invisible decay channel for the Higgs boson are also taken into account, in order to anticipate a possible confirmation of deficits in the branching ratios into ZZZZ^*, WWWW^*, bottom quarks, and tau leptons.Comment: 16 pages, 5 figure

    Probing 3-3-1 Models in Diphoton Higgs Boson Decay

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    We investigate the Higgs boson production through gluon fusion and its decay into two photons at the LHC in the context of the minimal 3-3-1 model and its alternative version with exotic leptons. The diphoton Higgs decay channel presents an enhanced signal in this model compared to the Standard Model due to the presence of an extra singly charged vector boson and a doubly charged one. Prospects for the Higgs boson detection at 7 TeV center-of-mass energy with up to 10 fb1^{-1} are presented. Our results suggest that a Higgs boson from these 3-3-1 models can potentially explain the small excess for mH145m_H\leq 145 GeV observed at the LHC. Otherwise, if this excess reveals to be only a statistical fluctuation of the Standard Model backgrounds severe constraints can be put on these models.Comment: Corrections in the text done, 24 pages, 5 figure

    Impacto de las Políticas Agrícolas de Comercialización en la Agricultura Familiar de la Región Sur del Estado de Tocantins

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    This work aims to assess the impact of government programs purchase food (PAA and PNAE) from family farming in the southern region of the state of Tocantins in marketing income. By the method of Propensity Score Matching two groups, family farmers selling (treatment group) and do not sell (control group) to government programs through these groups pairing between the farmers, so that they can be performed are taken compare like-minded individuals in relation to their observable characteristics. It verified that the programs contribute to increase financial income of family farming groups, especially in marketing rent.Este trabajo tiene como objetivo evaluar el impacto de los programas gubernamentales de compra de alimentos (PAA y PNAE) provenientes de la agricultura familiar de la región sur del estado de Tocantins en la renta de comercialización. Mediante el método de Propensity Score Matching se toman dos grupos, agricultores familiares que venden (grupo de tratamiento) y no venden (grupo de control) a los programas gubernamentales, mediante estos grupos se realiza el emparejamiento entre los agricultores, de modo que se puedan comparar individuos semejantes con relación a sus características observables. Se verifica que los programas contribuyen para aumentar los ingresos financieros de los grupos de la agricultura familiar, especialmente en la renta de comercialización. Agricultura Familiar. Programa de Adquisición de Alimentos. Programa Nacional de Alimentación Escolar

    Meta Heuristic for WDM Optical Networks Without Wavelength Conversion

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    This paper presents the results of the algorithm Snake-Two, evolving from algorithm Snake-One, which showed important results in the blocking probability of transport networks under dynamic traffic, but poor results in the network utilization indicator. The strategy applied is called Saturated Link and it moves traffic to congestion zones, creating concentrated network utilization, thus improving blocking probability. This is achieved by monitoring congested links using the full saturation capacity of each link. This way, the ones least used are downloaded, which enables keeping the congestion zoned and saturated, significantly lowering the blocking probability with low network utilization cost for dynamic traffic scenarios

    Implementing open-source information systems for assessing and managing the seismic vulnerability of historical constructions

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    The characterisation of the seismic vulnerability of historical constructions represents a complex problem in which the typological variability, the difficulty of performing reliable large-scale assessments and dealing with a large database all play a role. Nevertheless, reducing the uncertainty regarding the structural vulnerability of the existing building stock (mostly for small and/or isolated human settlements) is key for risk assessment and management. The present work proposes a novel approach based on the integration of a series of open-source tools for assembling a vulnerability-oriented database that is linked to a series of external services for increasing its capabilities. The database was implemented in a Geographical Information System (GIS) environment and contains the survey of a seismic vulnerability index for masonry constructions based on an adapted version of the GNDT-II approach. A customised Python-based software for reading, managing and editing the database is herein presented. This program allows the execution of the most typical operations with no assistance from the GIS environment, facilitating user interaction. Furthermore, the calculations regarding the vulnerability index and levels of damage have been implemented in this program. Alternatives for distributing the database are implemented and discussed, such as cloud-based distribution and the use of the Transactional Web Feature Service (WFS-T) protocol for its virtual publishing. The entire framework herein presented is a replicable and feasible workflow that can be set even with reduced infrastructure, allowing a progressive enlargement
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