102 research outputs found

    Iris Codes Classification Using Discriminant and Witness Directions

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    The main topic discussed in this paper is how to use intelligence for biometric decision defuzzification. A neural training model is proposed and tested here as a possible solution for dealing with natural fuzzification that appears between the intra- and inter-class distribution of scores computed during iris recognition tests. It is shown here that the use of proposed neural network support leads to an improvement in the artificial perception of the separation between the intra- and inter-class score distributions by moving them away from each other.Comment: 6 pages, 5 figures, Proc. 5th IEEE Int. Symp. on Computational Intelligence and Intelligent Informatics (Floriana, Malta, September 15-17), ISBN: 978-1-4577-1861-8 (electronic), 978-1-4577-1860-1 (print

    Modeling and Simulating a Novel Biohydrogen Production Technology as an Integrated Part of a Municipal Wastewater Treatment Plant

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    A series of mathematical models and simulations was developed and performed using BioWin software suit in order to determine the suitability of implementing a biohydrogen production technology in an existing wastewater treatment plant. The evaluation of the performance of these approach was based on biohydrogen yield and effluent quality. The simulations show high biohydrogen production rates, with picks during the summer months, while most of the effluent environmental parameters remain at the same or even lower levels compared with the currently used technology

    A 3D cone beam computed tomography study of the styloid process of the temporal bone

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    Background: To investigate the length and three-dimensional orientation and to detail the morphological variations of the styloid process.Materials and methods: Forty-four patients undergoing temporal bone evaluation for different reasons were randomly selected and included in the present study. The length, angulation in the coronal and sagittal planes, as well as morphological variations of the styloid processes were assessed using conebeam computer tomography. Pearson’s correlation coefficient was used to test possible associations between the length of styloid process and angulations, as well as between angulations. Student’s t-test was used to compare the differencesbetween the sample mean length and angulations in normal and elongated styloid process groups.Results: The sagittal angle showed weak positive correlations with the styloid process length and the transverse angle (r = 0.24, p = 0.02, n = 88). A medium positive correlation was found between the sagittal and transverse angulations in the elongated styloid process group (r = 0.49, p = 0.0015, n = 38).There was a statistical significant difference between the mean sagittal angulation in elongated styloid and normal styloid process groups (p = 0.015). The styloid process morphology also varied in terms of shape, number, and degree of ossification.Conclusions: The morphometric and morphologic variations of the styloid process may be important factors to be taken into account not only from the viewpoint of styloid syndromes, but also in preoperatory planning and during surgery

    Thermal expansivity and degradation properties of PLA/HA and PLA/ bTCP in vitro conditioned composites

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    [EN] The objective of this study was to investigate the thermal expansivities and degradation properties for several in vitro conditioned biodegradable poly(lactic acid)/hydroxyapatite (PLA/HA) and poly(lactic acid)/b-tricalcium phosphate (PLA/ bTCP) composites with different mass% of the particle reinforcements (i.e. 10, 20 and 30). The samples were prepared by extrusion followed by injection moulding and incubated in a customized simulated body fluid at 37 C over 60, 90, 120, 150 and 180 days, respectively. Thermal expansion and degradation properties of in vitro conditioned samples, along with dynamic mechanical properties of unconditioned ones, were systematically investigated through coefficients of linear thermal expansion and thermal strain changes, decomposition temperatures, mass changes and per cent residues. The results indicated that PLA/bTCP composites performed better than PLA/HA composites, irrespective of their filler mass%, revealing high values of glass transition temperatures, around a mean value of 65 C, both on dynamic mechanical analysis and on dilatation measurements but lower values on their degradation temperatures, such as 360 C. The results suggest the feasibility of tailoring high-loaded osteoconductive fillers-reinforced PLA composites for various medical and engineering applications.Ferri, JM.; Motoc, DL.; Ferrándiz Bou, S.; Balart, R. (2019). Thermal expansivity and degradation properties of PLA/HA and PLA/ bTCP in vitro conditioned composites. Journal of Thermal Analysis and Calorimetry (Online). 138(4):2691-2702. https://doi.org/10.1007/s10973-019-08799-0S269127021384Auras R, Lim LT, Selke S, Tsuji H. Poly(lactic acid): structures, production, synthesis, and applications. New York: Wiley; 2010.Murariu M, Dubois P. PLA composites: from production to properties. Adv Drug Deliv Rev. 2016;107:17–46.Haaparanta A-M, Haimi S, Ellä V, Hopper N, Miettinen S, Suuronen R, et al. Porous polylactide/β-tricalcium phosphate composite scaffolds for tissue engineering applications. J Tissue Eng Regen Med. 2010;4(5):366–73.Ahmed J, Varshney SK. Polylactides—chemistry, properties and green packaging technology: a review. Int J Food Prop. 2011;14(1):37–58.Garlotta D. A literature review of poly(lactic acid). J Polym Environ. 2001;9(2):63–84.Slomkowski S, Penczek S, Duda A. Polylactides—an overview. Polym Adv Technol. 2014;25(5):436–47.Avinc O, Khoddami A. Overview of poly(lactic acid) (PLA) fibre. Fibre Chem. 2009;41(6):391–401.Akindoyo JO, Beg MDH, Ghazali S, Heim HP, Feldmann M. Impact modified PLA-hydroxyapatite composites—thermo-mechanical properties. Compos A Appl Sci Manuf. 2018;107:326–33.Nazhat SN, Kellomäki M, Törmälä P, Tanner KE, Bonfield W. Dynamic mechanical characterization of biodegradable composites of hydroxyapatite and polylactides. J Biomed Mater Res. 2001;58(4):335–43.Ignjatovic N, Uskokovic D. Synthesis and application of hydroxyapatite/polylactide composite biomaterial. Appl Surf Sci. 2004;238(1):314–9.Li J, Zheng W, Li L, Zheng Y, Lou X. Thermal degradation kinetics of g-HA/PLA composite. Thermochim Acta. 2009;493(1):90–5.Zhang SM, Liu J, Zhou W, Cheng L, Guo XD. Interfacial fabrication and property of hydroxyapatite/polylactide resorbable bone fixation composites. Curr Appl Phys. 2005;5(5):516–8.Akindoyo JO, Beg MDH, Ghazali S, Heim HP, Feldmann M. Effects of surface modification on dispersion, mechanical, thermal and dynamic mechanical properties of injection molded PLA-hydroxyapatite composites. Compos A Appl Sci Manuf. 2017;103:96–105.Kang Y, Yao Y, Yin G, Huang Z, Liao X, Xu X, et al. A study on the in vitro degradation properties of poly(l-lactic acid)/β-tricalcuim phosphate(PLLA/β-TCP) scaffold under dynamic loading. Med Eng Phys. 2009;31(5):589–94.Huang J, Ten E, Liu G, Finzen M, Yu W, Lee JS, et al. Biocomposites of pHEMA with HA/β-TCP (60/40) for bone tissue engineering: swelling, hydrolytic degradation, and in vitro behavior. Polymer. 2013;54(3):1197–207.Bleach NC, Nazhat SN, Tanner KE, Kellomäki M, Törmälä P. Effect of filler content on mechanical and dynamic mechanical properties of particulate biphasic calcium phosphate—polylactide composites. Biomaterials. 2002;23(7):1579–85.Ferri J, Gisbert I, García-Sanoguera D, Reig M, Balart R. The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid). J Compos Mater. 2016;50(30):4189–98.Li X, Qi C, Han L, Chu C, Bai J, Guo C, et al. Influence of dynamic compressive loading on the in vitro degradation behavior of pure PLA and Mg/PLA composite. Acta Biomater. 2017;64:269–78.Agrawal CM, McKinney JS, Lanctot D, Athanasiou KA. Effects of fluid flow on the in vitro degradation kinetics of biodegradable scaffolds for tissue engineering. 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Mater Sci Eng C. 2015;47:237–47.Corcione C, Scalera F, Gervaso F, Montagna F, Sannino A, Maffezzoli A. One-step solvent-free process for the fabrication of high loaded PLA/HA composite filament for 3D printing. J Therm Anal Calorim. 2018;134:1–8.Siqueira L, Passador FR, Costa MM, Lobo AO, Sousa E. Influence of the addition of β-TCP on the morphology, thermal properties and cell viability of poly (lactic acid) fibers obtained by electrospinning. Mater Sci Eng C. 2015;52:135–43.Drummer D, Cifuentes-Cuéllar S, Rietzel D. Suitability of PLA/TCP for fused deposition modeling. Rapid Prototyp J. 2012;18(6):500–7.Ferri J, Jordá J, Montanes N, Fenollar O, Balart R. Manufacturing and characterization of poly(lactic acid) composites with hydroxyapatite. J Thermoplast Compos Mater. 2018;31(7):865–81.Menczel JD, Prime RB. Thermal analysis of polymers: fundamentals and applications. New York: Wiley; 2014.Aboudi J, Arnold SM, Bednarcyk BA. Chapter 3—fundamentals of the mechanics of multiphase materials. In: Aboudi J, Arnold SM, Bednarcyk BA, editors. Micromechanics of composite materials. Oxford: Butterworth-Heinemann; 2013. p. 87–145.Esposito Corcione C, Gervaso F, Scalera F, Padmanabhan SK, Madaghiele M, Montagna F, et al. Highly loaded hydroxyapatite microsphere/PLA porous scaffolds obtained by fused deposition modelling. Ceram Int. 2018;45:2803–10.Zou H, Yi C, Wang L, Liu H, Xu W. Thermal degradation of poly(lactic acid) measured by thermogravimetry coupled to Fourier transform infrared spectroscopy. J Therm Anal Calorim. 2009;97(3):929.Schindler A, Doedt M, Gezgin Ş, Menzel J, Schmölzer S. Identification of polymers by means of DSC, TG, STA and computer-assisted database search. J Therm Anal Calorim. 2017;129(2):833–42.Lee WA, Knight GJ. Ratio of the glass transition temperature to the melting point in polymers. Br Polym J. 1970;2(1):73–80

    Thermal properties comparison of hybrid CF/FF and BF/FF cyanate ester-based composites

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    [EN] Insights within thermal expansion, conductivity, and decomposition dependencies with temperature on symmetrical and unsymmetrical layered carbon (CF) or basalt (BF) fabrics in combination with flax fibers (FF) were approached. Driven by commercial application and environmental concerns, the paper draws attention on a modified formula of cyanate ester with a common epoxy resin under an optimized ratio of 70:30 (vol%) as well as on the hybrid reinforcements stacking sequences. Synergetic effects were debated in terms of the CF and BF stacking sequences and corresponding volume fraction followed by comparisons with values predicted by the deployment of hybrid mixtures rules (RoHM/iRoHM). CF hybrid architectures revealed enhanced effective thermophysical properties over their BF counterparts and both over the FF-reinforced polymer composite considered as a reference. Thermal conductivities spread between 0.116 and 0.299 W m-1 K-1 from room temperature up to 250 C on all hybrid specimens, giving rise to an insulator character. Concerning the coefficient of thermal expansion, CF hybrid architectures disclosed values of 1.236 10-6 K-1 and 3.102 10-6 K-1 compared with BF affine exhibiting 4.794 10-6 K-1 and 6.245 10-6 K-1, respectively, with an increase in their volume fraction.The corresponding author gratefully acknowledges the financial assistance of German Academic Exchange Service-DAAD that enabled and supported the internship with Fraunhofer Research Institution for Polymeric Materials and Composites-PYCO, Germany. Many thanks go to Dr. Christian Dreyer and Dr. Maciej Gwiazda for the resin formula and access to the composite manufacturing technology.Motoc, DL.; Ferrándiz Bou, S.; Balart, R. (2018). Thermal properties comparison of hybrid CF/FF and BF/FF cyanate ester-based composites. Journal of Thermal Analysis and Calorimetry. 133(1):509-518. https://doi.org/10.1007/s10973-018-7222-yS5095181331Assarar M, Zouari W, Sabhi H, Ayad R, Berthelot J-M. Evaluation of the damping of hybrid carbon–flax reinforced composites. Compos Struct. 2015;132:148–54.Duc F, Bourban PE, Plummer CJG, Månson JAE. Damping of thermoset and thermoplastic flax fibre composites. Compos A Appl Sci Manuf. 2014;64:115–23.Saba N, Jawaid M, Alothman OY, Paridah MT. A review on dynamic mechanical properties of natural fibre reinforced polymer composites. Constr Build Mater. 2016;106:149–59.Tian H, Zhang S, Ge X, Xiang A. Crystallization behaviors and mechanical properties of carbon fiber-reinforced polypropylene composites. J Therm Anal Calorim. 2017;128(3):1495–504.Alvarez V, Rodriguez E, Vázquez A. Thermaldegradation and decomposition of jute/vinylester composites. J Therm Anal Calorim. 2006;85(2):383–9.Manfredi LB, Rodríguez ES, Wladyka-Przybylak M, Vázquez A. Thermal degradation and fire resistance of unsaturated polyester, modified acrylic resins and their composites with natural fibres. Polym Degrad Stab. 2006;91(2):255–61.Lazko J, Landercy N, Laoutid F, Dangreau L, Huguet MH, Talon O. Flame retardant treatments of insulating agro-materials from flax short fibres. Polym Degrad Stab. 2013;98(5):1043–51.Bar M, Alagirusamy R, Das A. Flame retardant polymer composites. Fibers Polym. 2015;16(4):705–17.Kollia E, Loutas T, Fiamegkou E, Vavouliotis A, Kostopoulos V. Degradation behavior of glass fiber reinforced cyanate ester composites under hydrothermal ageing. Polym Degrad Stab. 2015;121:200–7.Jawaid M, Abdul Khalil HPS. Cellulosic/synthetic fibre reinforced polymer hybrid composites: a review. Carbohyd Polym. 2011;86(1):1–18.Azwa ZN, Yousif BF, Manalo AC, Karunasena W. A review on the degradability of polymeric composites based on natural fibres. Mater Des. 2013;47:424–42.H-y Cheung, M-p Ho, K-t Lau, Cardona F, Hui D. 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Effect of fiber loading on the properties of treated cellulose fiber-reinforced phenolic composites. Compos B Eng. 2015;68:185–92.LeGault M. Natural fiber composites: market share, one part at the time. Compos World. 2016;5(2):68–75.Joshi SV, Drzal LT, Mohanty AK, Arora S. Are natural fiber composites environmentally superior to glass fiber reinforced composites? Compos A Appl Sci Manuf. 2004;35(3):371–6.Wambua P, Ivens J, Verpoest I. Natural fibres: can they replace glass in fibre reinforced plastics? Compos Sci Technol. 2003;63(9):1259–64.Bertomeu D, García-Sanoguera D, Fenollar O, Boronat T, Balart R. Use of eco-friendly epoxy resins from renewable resources as potential substitutes of petrochemical epoxy resins for ambient cured composites with flax reinforcements. Polym Compos. 2012;33(5):683–92.Alam M, Akram D, Sharmin E, Zafar F, Ahmad S. Vegetable oil based eco-friendly coating materials: a review article. 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    Land use mix and physical activity in middle-aged and older adults: a longitudinal study examining changes in land use mix in two Dutch cohorts

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    Background: With urbanization and aging increasing in coming decades, societies face the challenge of keeping aging populations active. Land use mix (LUM) has been associated with cycling and walking, but whether changes in LUM relate to changes in cycling/walking is less known. Objectives: Our objective was to study the effect of LUM on cycling/walking in two Dutch aging cohorts using data with 10 years of follow-up. Methods: Data from 1183 respondents from the Health and Living Conditions of the Population of Eindhoven and Surroundings (GLOBE) study and 918 respondents from the Longitudinal Aging Study Amsterdam (LASA) were linked to LUM in 1000-m sausage network buffers at three time-points. Cycling/walking outcomes were harmonized to include average minutes spent cycling/walking per week. Data was pooled and limited to respondents that did not relocate between follow-up waves. Associations between LUM and cycling/walking were estimated using a Random Effects Within-Between (REWB) model that allows for the estimation of both within and between effects. Sensitivity analyses were performed on smaller (500-m) and larger (1600-m) buffers. Results: We found evidence of between-individual associations of LUM in 1000-m buffers and walking (β: 11.10, 95% CI: 0.08; 21.12), but no evidence of within-associations in 1000-m buffers. Sensitivity analyses using 500-m buffers showed similar between-associations, but negative within-associations (β: -35.67, 95% CI: − 68.85; − 2.49). We did not find evidence of between-individual associations of LUM in any buffer size and cycling, but did find evidence of negative within-associations between LUM in 1600-m buffers and cycling (β: -7.49, 95% CI: − 14.31; − 0.66). Discussion: Our study found evidence of positive associations between LUM and average walking time, but also some evidence of negative associations between a change in LUM and cycling/walking. LUM appears to be related to cycling/walking, but the effect of changes in LUM on cycling/walking is unclear

    Green spaces, subjective health and depressed affect in middle-aged and older adults: A cross-country comparison of four European cohorts

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    Background: Studies on associations between urban green space and mental health have yielded mixed results. This study examines associations of green space exposures with subjective health and depressed affect of middle-aged and older adults in four European cohorts. Methods: Data came from four Western-European and Central-European ageing cohorts harmonised as part of the Mindmap project, comprising 16 189 adults with an average age of 50-71 years. Green space exposure was based on the distance to the nearest green space and the amount of green space within 800 m buffers around residential addresses. Cohort-specific and one-step individual participant data (IPD) meta-analyses were used to examine associations of green space exposures with subjective health and depressed affect. Results: The amount of green spaces within 800 m buffers was lowest for Residential Environment and CORonary heart Disease (Paris, 15.0 hectares) and highest for Health, Alcohol and Psychosocial factors In Eastern Europe (Czech Republic, 35.9 hectares). IPD analyses indicated no evidence of an association between the distance to the nearest green space and depressed affect (OR 0.98, 95% CI 0.96 to 1.00) or good self-rated health (OR 1.01, 95% CI 0.99 to 1.02). Likewise, the amount of green space within 800 m buffers did not predict depressed affect (OR 0.98, 95% CI 0.96 to 1.00) or good self-rated health (OR 1.01, 95% CI 0.99 to 1.02). Findings were consistent across all cohorts. Conclusions: Data from four European ageing cohorts provide no support for the hypothesis that green space exposure is associated with subjective health or depressed affect. While longitudinal evidence is required, these findings suggest that green space may be less important for older urban residents

    Exposome-Wide Association Study of Body Mass Index Using a Novel Meta-Analytical Approach for Random Forest Models

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    BACKGROUND: Overweight and obesity impose a considerable individual and social burden, and the urban environments might encompass factors that contribute to obesity. Nevertheless, there is a scarcity of research that takes into account the simultaneous interaction of multiple environmental factors. OBJECTIVES: Our objective was to perform an exposome-wide association study of body mass index (BMI) in a multicohort setting of 15 studies. METHODS: Studies were affiliated with the Dutch Geoscience and Health Cohort Consortium (GECCO), had different population sizes (688-141,825), and covered the entire Netherlands. Ten studies contained general population samples, others focused on specific populations including people with diabetes or impaired hearing. BMI was calculated from self-reported or measured height and weight. Associations with 69 residential neighborhood environmental factors (air pollution, noise, temperature, neighborhood socioeconomic and demographic factors, food environment, drivability, and walkability) were explored. Random forest (RF) regression addressed potential nonlinear and nonadditive associations. In the absence of formal methods for multimodel inference for RF, a rank aggregation-based meta-analytic strategy was used to summarize the results across the studies. RESULTS: Six exposures were associated with BMI: five indicating neighborhood economic or social environments (average home values, percentage of high-income residents, average income, livability score, share of single residents) and one indicating the physical activity environment (walkability in formula presented buffer area). Living in high-income neighborhoods and neighborhoods with higher livability scores was associated with lower BMI. Nonlinear associations were observed with neighborhood home values in all studies. Lower neighborhood home values were associated with higher BMI scores but only for values up to formula presented . The directions of associations were less consistent for walkability and share of single residents. DISCUSSION: Rank aggregation made it possible to flexibly combine the results from various studies, although between-study heterogeneity could not be estimated quantitatively based on RF models. Neighborhood social, economic, and physical environments had the strongest associations with BMI. https://doi.org/10.1289/EHP13393.</p
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