289 research outputs found
Crop intensification, land use, and on-farm energy-use efficiency during the worldwide spread of the green revolution
We analyzed crop production, physical inputs, and land use at the country level to assess technological changes behind the threefold increase in global crop production from 1961 to 2014. We translated machinery, fuel, and fertilizer to embedded energy units that, when summed up, provided a measure of agricultural intensification (human subsidy per hectare) for crops in the 58 countries responsible for 95% of global production. Worldwide,there was a 137% increase in input use per hectare, reaching 13 EJ, or 2.6% of the world´s primary energy supply, versus only a 10% increase in land use. Intensification was marked in Asia and Latin America, where input-use levels reached those that North America and Europe had in the earlier years of the period; the increase was more accentuated, irrespective of continent, for the 12 countries with mostly irrigated production. Half of the countries (28/58), mainly developed ones, had an average subsidy >5 GJ/ha/y (with fertilizers accounting for 27% in 1961 and 45% in 2014), with most of them (23/28) using about the same area or less than in 1961 (net land sparing of 31 Mha). Most of the remaining countries (24/30 with inputs <5 GJ/ha/y), mainly developing ones, increased their cropped area (net land extensification of 135 Mha). Overall, energy-use efficiency (cropoutput/inputs) followed a U-shaped trajectory starting at about 3 and finishing close to 4. The prospects of a more sustainable intensification are discussed, and the inadequacy of the land-sparing model expectation of protecting wilderness via intensified agriculture is highlighted.Fil: PELLEGRINI, PEDRO. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de AgronomÃa. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: FERNANDEZ, Roberto J.. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de AgronomÃa. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin
Localization of elastic deformation in strongly anisotropic, porous, linear materials with periodic microstructures: exact solutions and dilute expansions
Exact solutions are derived for the problem of a two-dimensional, infinitely
anisotropic, linear-elastic medium containing a periodic lattice of voids. The
matrix material possesses either one infinitely soft, or one infinitely hard
loading direction, which induces localized (singular) field configurations. The
effective elastic moduli are computed as functions of the porosity in each
case. Their dilute expansions feature half-integer powers of the porosity,
which can be correlated to the localized field patterns. Statistical
characterizations of the fields, such as their first moments and their
histograms are provided, with particular emphasis on the singularities of the
latter. The behavior of the system near the void close packing fraction is also
investigated. The results of this work shed light on corresponding results for
strongly nonlinear porous media, which have been obtained recently by means of
the ``second-order'' homogenization method, and where the dilute estimates also
exhibit fractional powers of the porosity.Comment: 22 pages, 10 figure
Effective-medium theory for infinite-contrast two-dimensionally periodic linear composites with strongly anisotropic matrix behavior: Dilute limit and crossover behavior
The overall behavior of a two-dimensional lattice of voids embedded in an anisotropic elastic matrix is investigated in the limit of vanishing porosity f. An effective-medium model (of the Clausius-Mossoti type), which accounts for elastic interactions between neighboring voids, is compared to fast Fourier transform numerical solutions and, in the limits of infinite anisotropy, to exact results. A crossover between regular and singular dilute regimes is found, driven by a characteristic length which depends on f and on the anisotropy strength. The singular regime, where the leading dilute correction to the elastic moduli is an O(f1/2), is related to strain localization and to change in character—from elliptic to hyperbolic—of the governing equations
Hemoglobin sickle cell disease in Brazil
Universidade Federal de São Paulo, Escola Paulista Med, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, São Paulo, BrazilWeb of Scienc
Molecular analysis and association with clinical and laboratory manifestations in children with sickle cell anemia
Objectives: To analyze the frequency of βS-globin haplotypes and alpha-thalassemia, and their influence on clinical manifestations and the hematological profile of children with sickle cell anemia.Method: The frequency of βS-globin haplotypes and alpha-thalassemia and any association with clinical and laboratorial manifestations were determined in 117 sickle cell anemia children aged 3–71 months. The confirmation of hemoglobin SS and determination of the haplotypes were achieved by polymerase chain reaction-restriction fragment length polymorphism, and alpha-thalassemia genotyping was by multiplex polymerase chain reaction (single-tube multiplex-polymerase chain reaction).Results: The genotype distribution of haplotypes was 43 (36.7%) Central African Republic/Benin, 41 (35.0%) Central African Republic/Central African Republic, 20 (17.0%) Rare/atypical, and 13 (11.1%) Benin/Benin. The frequency of the α3.7 deletion was 1.71% as homozygous (−α3.7/−α3.7) and 11.9% as heterozygous (−α3.7/αα). The only significant association in respect to haplotypes was related to the mean corpuscular volume. The presence of alpha-thalassemia was significantly associated to decreases in mean corpuscular volume, mean corpuscular hemoglobin and reticulocyte count and to an increase in the red blood cell count. There were no significant associations of βS-globin haplotypes and alpha-thalassemia with clinical manifestations.Conclusions: In the study population, the frequency of alpha-thalassemia was similar to published data in Brazil with the Central African Republic haplotype being the most common, followed by the Benin haplotype. βS-globin haplotypes and interaction between alpha-thalassemia and sickle cell anemia did not influence fetal hemoglobin concentrations or the number of clinical manifestations.Universidade Federal de São Paulo (UNIFESP)UNIFESPSciEL
Ovarian cancer G protein-coupled receptor 1 deficiency exacerbates crystal deposition and kidney injury in oxalate nephropathy in female mice
Ovarian cancer G protein-coupled receptor 1 (OGR1) (Gpr68) and G protein-coupled receptor 4 (GPR4) (Gpr4) are proton-activated G protein-coupled receptors that are stimulated upon increased extracellular acidity. These receptors have various physiological and pathophysiological roles in renal acid–base physiology, tissue inflammation, and fibrosis among others. Their function in injured renal tissue, however, remains mostly unclear. To address this, we investigated their role in crystalline nephropathy by increasing the oxalate intake of GPR4 KO and OGR1 KO mice.
After 10 days of high-oxalate intake and 4 days of recovery, renal crystal content, histopathology, filtration function, and inflammation were assessed. While GPR4 deficiency did not show major alterations in disease progression, OGR1 KO mice had higher urinary calcium levels and exacerbated crystal accumulation accompanied by decreased creatinine clearance and urea excretion and a decreased presence of regulatory T (Treg) cells in kidney tissue. When lowering the severity of the kidney injury, OGR1 KO mice were more prone to develop crystalline nephropathy. In this setting, OGR1 KO mice displayed an increased activation of the immune system and a higher production of proinflammatory cytokines by T cells and macrophages.
Taken together, in the acute setting of oxalate-induced nephropathy, the lack of the proton-activated G protein-coupled receptor (GPCR) GPR4 does not influence disease. OGR1 deficiency, however, increases crystal deposition leading to impaired kidney function. Thus, OGR1 may be important to limit kidney crystal deposition, which might subsequently be relevant for the pathophysiology of oxalate kidney stones or other crystallopathies
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