EIO-Artigoshttp://hdl.handle.net/10347/139512021-01-25T00:22:07Z2021-01-25T00:22:07ZPositive periodic solutions for impulsive differential equations with infinite delay and applications to integro‐differential equationsBuedo Fernández, SebastiánFaria, Teresahttp://hdl.handle.net/10347/242592021-01-22T03:00:50Z2020-01-01T00:00:00ZPositive periodic solutions for impulsive differential equations with infinite delay and applications to integro‐differential equations
Buedo Fernández, Sebastián; Faria, Teresa
Sufficient conditions for the existence of at least one positive periodic solution are established for a family of scalar periodic differential equations with infinite delay and nonlinear impulses. Our criteria, obtained by applying a fixed‐point argument to an original operator constructed here, allow to treat equations incorporating a rather general nonlinearity and impulses whose signs may vary. Applications to some classes of Volterra integro‐differential equations with unbounded or periodic delay and nonlinear impulses are given, extending and improving results in the literature.
This is the accepted version of the following article: Buedo‐Fernández, S, Faria, T. Positive periodic solutions for impulsive differential equations with infinite delay and applications to integro‐differential equations. Math Meth Appl Sci. 2020; 43: 3052–3075, which has been published in final form at https://doi.org/10.1002/mma.6100. This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving Policy http://www.wileyauthors.com/self-archiving
2020-01-01T00:00:00ZSoil organic carbon in peninsular Spain: Influence of environmental factors and spatial distributionCalvo de Anta, Rosa MaríaLuis Calvo, ElíasFebrero Bande, ManuelGaliñanes Costa, Juan ManuelMacías Vázquez, FelipeOrtíz, RoqueCasás Sabarís, Franciscohttp://hdl.handle.net/10347/242522021-01-21T03:00:54Z2020-01-01T00:00:00ZSoil organic carbon in peninsular Spain: Influence of environmental factors and spatial distribution
Calvo de Anta, Rosa María; Luis Calvo, Elías; Febrero Bande, Manuel; Galiñanes Costa, Juan Manuel; Macías Vázquez, Felipe; Ortíz, Roque; Casás Sabarís, Francisco
Soil organic carbon (SOC) stocks and their geographical distribution in peninsular Spain were estimated from a georeferenced database consisting of 12,724 surface samples (0–30 cm) and 3607 subsurface samples (30–50 cm), covering different climate, land use, elevation, parent material, soil type and soil pH. SOC density showed a high heterogeneity, with the lowest values in arid regions, where the average in topsoil ranged between 20 and 60 t C ha−1, under woody crops and forest respectively. Carbon stocks gradually increases as precipitation increases, and its variability is also dependent of other factors, fundamentally the presence/absence of active lime or active Al. In semi-arid zones, calcaric soils (pH ≈ 8.3) have higher contents of SOC than neutral to weakly acidic soils from siliceous materials. However, in humid regions, calcareous materials have undergo total or partial decarbonatation in the upper layer (pH < 4.0–7.5) and SOC stocks are markedly lower than in other materials. In forest soils it seems that a steady state (around 100–120 t C ha−1) (0–30 cm) has been reached in a wide range of precipitation, between 900 and 1700 mm; most of this carbon (about 80%) is labile-C. Soils from granitic rocks are acidic (pH 4.5–5.5) (Al buffering) and the mean SOC stock in the indicated precipitation range is between 170 and 200 t ha−1 (it is estimated that approximately 60% is stabilized as metal-C or mineral-C complexes). The highest values (190–240 t ha−1) are recorded in acidic soils derived from mafic rocks, which in these regions usually develop andic properties (around 73% is involved in stable metal-C or mineral C complexes). Finally, the SOC stored in neutral soils from serpentinized ultramafic rocks (without excess Ca or Al) is similar to that of the decarbonated soils derived from calcareous materials. In all regions, forest soils are a much more important SOC sink than live forest biomass (2–4 times higher in the upper 30 cm and 3–6 times greater in the upper 50 cm).
Random Forest regression was used as modeling tool and digital mapping. Mean annual precipitation was estimated to be the most important predictor variable, followed by land use, lithology/soil type and soil pH. Model performance was calibrated by the internal RF validation and through cross-validation, and the results were similar. In topsoil, the mean error, root mean square error and R2 were −0.007% C, 1.48% C and 0.61, respectively. In the subsurface layer these indices were −0.020, 1.07 and 0.37, respectively. SOC stock for peninsular Spain was estimated at 3.33 Pg in the upper (0–30 cm) layer, and 0.85 Pg in the subsurface (30–50 cm) layer. Total SOC stock for 0–50 cm was 4.19 Pg, with a 95% confidence interval ranging between 3.33 and 5.03 Pg
2020-01-01T00:00:00ZGlycemic Variability and Its Association With Demographics and Lifestyles in a General Adult PopulationGude SampedroGude Sampedro, FranciscoDíaz Vidal, PabloRúa Pérez, CintiaAlonso Sampedro, ManuelaFernández Merino, CarmenRey García, JesúsCadarso Suárez, Carmen MaríaPazos Couselo, MarcosGarcía López, José ManuelGonzález Quintela, Arturohttp://hdl.handle.net/10347/242412021-01-20T03:01:02Z2017-01-01T00:00:00ZGlycemic Variability and Its Association With Demographics and Lifestyles in a General Adult Population
Gude Sampedro; Gude Sampedro, Francisco; Díaz Vidal, Pablo; Rúa Pérez, Cintia; Alonso Sampedro, Manuela; Fernández Merino, Carmen; Rey García, Jesús; Cadarso Suárez, Carmen María; Pazos Couselo, Marcos; García López, José Manuel; González Quintela, Arturo
Objective: The objective was to investigate glycemic variability indices in relation to demographic factors and common environmental lifestyles in a general adult population.
Methods: The A Estrada Glycation and Inflammation Study is a cross-sectional study covering 1516 participants selected by sampling of the population aged 18 years and over. A subsample of 622 individuals participated in the Glycation project, which included continuous glucose monitoring procedures. Five glycemic variability indices were analyzed, that is, SD, MAGE, MAG, CONGA1, and MODD.
Results: Participants had a mean age of 48 years, 62% were females, and 12% had been previously diagnosed with diabetes. In the population without diabetes, index distributions were not normal but skewed to the right. Distributional regression models that adjusted for age, gender, BMI, alcohol intake, smoking status, and physical activity confirmed that all indices were positively and independently associated with fasting glucose levels and negatively with heavy drinking. SD, MAGE, and CONGA1 were positively associated with aging, and MAG was negatively associated with BMI. None of the GVI studied were influenced by physical activity. Age-group-specific reference values are given for the indices.
Conclusions: This study yielded age-specific reference values for glucose variability indices in a general adult population. Significant increases were observed with aging. Heavy drinking of more than 140 g/week was associated with significant decreases in variability indices. No differences were found between males and females. These normative ranges provide a guide for clinical care, and may offer an alternative treatment target among persons with diabetes
2017-01-01T00:00:00ZDissipativity of Fractional Navier–Stokes Equations with Variable DelayLiu, Lin F.Nieto Roig, Juan Joséhttp://hdl.handle.net/10347/240362021-01-09T03:08:52Z2020-01-01T00:00:00ZDissipativity of Fractional Navier–Stokes Equations with Variable Delay
Liu, Lin F.; Nieto Roig, Juan José
We use classical Galerkin approximations, the generalized Aubin–Lions Lemma as well as the Bellman–Gronwall Lemma to study the asymptotical behavior of a two-dimensional fractional Navier–Stokes equation with variable delay. By modifying the fractional Halanay inequality and the comparison principle, we investigate the dissipativity of the corresponding system, namely, we obtain the existence of global absorbing set. Besides, some available results are improved in this work. The existence of a global attracting set is still an open problem
2020-01-01T00:00:00Z