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San Antonio del Tachira, Venezuela

Hernandez P.,National Experimental University of Tachira | Cubillo S.,Technical University of Madrid | Torres-Blanc C.,Technical University of Madrid
Fuzzy Sets and Systems | Year: 2014

So far, the negation that usually has been considered within the type-2 fuzzy sets (T2FSs) framework, and hence T2FS truth values M (set of all functions from [0,1] to [0,1]), was obtained by means of Zadeh's extension principle and calculated from standard negation in [0,1]. But there has been no comparative analysis of the properties that hold for the above operation and the axioms that any negation in M should satisfy. This suggests that negations should be studied more thoroughly in this context. Following on from this, we introduce in this paper the axioms that an operation in M must satisfy to qualify as a negation and then prove that the usual negation on T2FSs, in particular, is antimonotonic in L (set of normal and convex functions of M) but not in M. We propose a family of operations calculated from any suprajective negation in [0,1] and prove that they are negations in L. Finally, we examine De Morgan's laws for some operations with respect to these negations. © 2013 Elsevier B.V. All rights reserved. Source


Rodriguez-Romero N.,National Experimental University of Tachira | Abecia L.,CSIC - Experimental Station of El Zaidin | Fondevila M.,University of Zaragoza | Balcells J.,University of Lleida
World Rabbit Science | Year: 2011

The effect of neutral detergent fibre (NDF) and neutral detergent soluble fibre (NDSF) on in vivo faecal digestibility and caecal fermentation pattern was studied in growing rabbits, in 4 diets formulated according to 2 levels of NDF, 370 (LI) and 450 (HI) g/kg, and 2 levels of NDSF, 150 (LS) and 180 (HS) g/ kg in substitution of starch, in a 2×2 factorial structure. Twenty four New Zealand White rabbits weaned at 28 d (630±80.2 g weight) were allocated to digestibility cages from 42 to 49 d of age to determine apparent faecal digestibility of each diet (n=6). Urine was collected for determination of purine derivatives (PD). Once the digestibility trial finished, rabbits were fitted with PVC neck collars for 24 h total caecotrophe collection. After 1 d of recovery, animals were slaughtered and caecal contents were used as inocula for 18 h in vitro gas production and caecal degradation (ivDMcD) study, using an HCI-pepsin and pancreatin pre-digested substrate. Diet digestibility was also determined by the in vitro three-step enzymatic procedure. There were no effects of the NDFxNDSF interaction for any digestibility parameter (P>0.10). Both dry matter and organic matter digestibility (DMd and OMd) decreased from 0.518 to 0.442 and from 0.526 to 0.447, respectively, with the increase of NDF (P<0.001), but were unaffected by the NDSF level (P>0.10). In contrast, NDF digestibility (NDFd) and ivDMcD did not respond to NDF (P>0.10) but increased from 0.156 to 0.200 and 0.141 to 0.210 with the proportion of NDSF (P<0.01). Weight of caecal contents Increased with both NDF (P<0.001) and NDSF content (P<0.01). However, total production of caecotrophes increased from 20.1 to 25.5 g DM/d with NDF (P<0.05), but was not affected by NDSF. The crude protein (CP) proportion in caecotrophes decreased with NDF (P<0.001) and increased with NDSF level (P<:0.01), and total CP recycled as caecotrophes tended (P=0.093) to be higher in HS diets, being unaffected by the dietary level of NDF. Diets rich in NDSF rendered higher gas volumes (P<0.001) than those with LS from 2 to 18 h incubation, whereas inclusion of high proportions of NDF reduced gas volume (P<0.01). Results indicate that NDF reduces faecal digestibility, whereas NDSF promotes better conditions for caecal fermentation. © WRSA UPV 2003. Source


Hernandez P.,National Experimental University of Tachira | Cubillo S.,Technical University of Madrid | Torres-Blanc C.,Technical University of Madrid
IEEE Transactions on Fuzzy Systems | Year: 2015

Type-2 fuzzy sets (T2FSs) were introduced by Zadeh in 1975 as an extension of type-1 fuzzy sets. The degree of membership of an element for T2FSs is a fuzzy set in [0, 1], that is, a T2FS is determined by a membership function from the universe of discourse X to M, where M is the set of functions from [0, 1] to [0, 1]. Walker and Walker extended the definitions of t-norm (triangular norm) and t-conorm to L (subset of normal and convex functions of M), establishing the tr-norms and tr-conorms (according to the 'restrictive axioms' given by them), and defined two families of binary operations on M and found that, under certain conditions, these operations are tr-norms or tr -conorms on L. In this paper, we introduce more general binary operations on M than those given by Walker and Walker and study which of the minimum conditions necessary for these operations satisfy each of the axioms of the tr-norm and t tr-conorm. In particular, interesting results about the closure properties are obtained, and the main result of the paper provides sufficient conditions for the given operations to be tr-norms or tr-conorms on L. © 1993-2012 IEEE. Source


Molina R.E.,National Experimental University of Tachira
Revista Mexicana de Astronomia y Astrofisica | Year: 2012

A number of empirical correlations that allow us to calculate the effective temperature and surface gravity for a set of evolved post-AGB and RV Tauri stars are determined using as calibrators the intrinsic colors of 2MASS (Two Micron All Sky Survey) photometry. We have analyzed a total sample of 36 stars of which 25 are post-AGB stars and 11 are RV Tauri stars, respectively. A group of 11 stars with parallax measures were used as calibrators of the absolute magnitude. The result for Teff and log g from intrinsic colors (J - H) 0 and (H - K s) 0 at the near-infrared pass bands reach a dispersion of 220 K and 0.27, respectively. We can estimate the absolute magnitude using the intrinsic color in the near-infrared band with an uncertainty of 0.28 mag. This indicates that (J -H) 0 and (H -K s) 0 show sensitivity to the absolute magnitude. © Copyright 2012: Instituto de Astronomía, Universidad Nacional Autónoma de México. Source


Rodriguez R.,Institute Ciencia Animal | Britos A.,University of the Republic of Uruguay | Rodriguez-Romero N.,National Experimental University of Tachira | Fondevila M.,University of Zaragoza
Animal Feed Science and Technology | Year: 2011

To what extent microbial fermentation of tropical grasses is affected by tannins from browse legumes was studied in vitro using acetone extracts from tanniferous plants in four 48. h incubation experiments. A proportion of plant extracts equivalent to 240. mg of Acacia cornigera (AC), Albizia lebbekoides (AL) and Leucaena leucocephala (LL) were added to each bottle with 800. mg Pennisetum purpureum as substrate, and contrasted with P. purpureum alone (PP) or with 64. mg quebracho tannins (QT). Gas production was lowest with QT and AL (P<0.05), and AC and LL reduced gas volume compared to PP from 10 to 24. h (P<0.001) and from 4 to 8. h (P<0.01), respectively. Compared with PP, total VFA concentration was reduced with AL and QT after 12. h (P<0.01), and the same trend (P=0.06) occurred with AC and AL after 24. h. Acetate molar proportion at 24. h was reduced, and that of propionate increased, with AC and AL compared with PP (P<0.05), whereas AL and QT reduced butyrate proportion (P<0.05). Estimated methane concentration per unit fermented organic matter after 24. h was lower with AC and AL than with PP (P<0.01). Proportion of R. albus was reduced with LL, AC and AL compared with PP at 12. h (P<0.01) and 24. h (P<0.001) of incubation, and the relative concentration of F. succinogenes tended (P=0.08) to be reduced with QT at 12. h, whereas there was no effect on R. flavefaciens. Plant extracts from A. cornigera, A. lebekkoides and L. leucocephala affected microbial fermentation of the tropical grass P. purpureum, reducing the rate of gas production from 4 to 16. h and increasing propionate at the expense of acetate, to the largest extent with A. lebbekoides. A reduction of methanogenesis, and therefore an increase in efficiency of energy utilisation, is consequently expected. No major effect on the bacterial population attached to the substrate occurred, but concentrations of R. albus seemed to be sensitive to tannins. © 2011 Elsevier B.V. Source

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