scholarly journals Examples of Hyperbolic Hypersurfaces of Low Degree in Projective Spaces

2015 ◽  
Vol 2016 (18) ◽  
pp. 5518-5558 ◽  
Author(s):  
Dinh Tuan Huynh
Keyword(s):  
Projective Spaces ◽  
Low Degree

scholarly journals Stable Rationality of del Pezzo Fibrations of Low Degree Over Projective Spaces

2018 ◽  
Vol 2020 (23) ◽  
pp. 9075-9119 ◽  
Author(s):  
Igor Krylov ◽  
Takuzo Okada
Keyword(s):  
Projective Space ◽  
Three Dimensional ◽  
Projective Spaces ◽  
Canonical Divisor ◽  
Stable Rationality ◽  
Higher Dimensional ◽  
Low Degree ◽  
Del Pezzo

Abstract The main aim of this article is to show that a very general three-dimensional del Pezzo fibration of degrees 1, 2, and 3 is not stably rational except for a del Pezzo fibration of degree 3 belonging to explicitly described two families. Higher-dimensional generalizations are also discussed and we prove that a very general del Pezzo fibration of degrees 1, 2, and 3 defined over the projective space is not stably rational provided that the anti-canonical divisor is not ample.

Assessment of Damage to Human Platelets after Aggregation and Other Injuries by Microscopic Observation and Estimation of Serotonin Uptake

1970 ◽  
Vol 23 (02) ◽  
pp. 261-275 ◽  
Author(s):  
G Zbinden ◽  
J. N Mehrishi ◽  
S Tomlin
Keyword(s):  
Platelet Aggregation ◽  
Electrophoretic Mobility ◽  
Human Platelets ◽  
Freezing And Thawing ◽  
Low Degree ◽  
Microscopic Evaluation ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Charged Macromolecules ◽  
5 Ht Uptake

SummaryThe severity of platelet damage induced by hyper- and hypotonic NaCl solutions and freezing and thawing was assessed by microscopic evaluation and measuring inhibition of 5-HT uptake. The same techniques were used to quantitate the effects of aggregating agents. The positively charged macromolecules PS, Poly-L und Poly-O reduced the net negative surface charge as determined by microelectrophoresis, caused platelet aggregation and inhibited 5-HT uptake. The damaging effects of Poly-L and Poly-O were more severe and more closely related to concentration than that of PS. The negatively charged macromolecules Poly-IC and NaPS increased the anodic electrophoretic mobility. Poly-IC and heparin caused a low degree of platelet clumping and no inhibition of 5-HT uptake. NaPS produced severe platelet damage with extensive clumping and complete inhibition of 5-HT uptake. Na laurate had the same effect, but did not alter electrophoretic mobility. ADP caused concentration-dependent platelet aggregation and inhibition of 5-HT uptake. The effects of ADP and NaPS were compared in agitated and non-agitated platelet samples containing identical concentrations of the 2 compounds. Agitation was found to increase the degree of platelet clumping and to reduce 5-HT uptake.

SOLOS FRÁGEIS DO PARQUE NACIONAL DA SERRA DA CAPIVARA, PIAUÍ

GEOgraphia ◽  
2018 ◽  
Vol 19 (41) ◽  
pp. 123
Author(s):  
Gustavo Souza Valladares ◽  
Cláudia Maria Sabóia de Aquino ◽  
Renê Pedro de Aquino ◽  
Raphael Moreira Beirigo
Keyword(s):  
Soil Conservation ◽  
National Park ◽  
Soil Classification ◽  
Degradation Process ◽  
Archaeological Sites ◽  
Small Depth ◽  
Palabras Clave ◽  
Low Degree ◽  
Chemical Attributes ◽  
Pelitic Rocks

Resumo: O Parque Nacional da Serra da Capivara (PNSC) tem alguns dos sítios arqueológicos mais importantes das Américas. A área onde os solos foram amostrados corresponde ao Parque Nacional da Serra da Capivara (PNSC) e uma área tampão de 10km no entorno de seus limites oficiais, no sudeste do Piauí. Para a elaboração do presente trabalho foram selecionados solos considerados frágeis, devido ao alto risco de degradação por erosão, formados de diferentes materiais geológicos representativos do PNSC. Todos os solos estudados são pouco evoluídos, com desenvolvimento pedogenético ainda incipiente, e enquadram-se nas ordens dos Neossolos ou Cambissolos. O bioma representativo da área de estudo é a caatinga, que pela vegetação com pouca biomassa e características decíduas confere pouca cobertura aos solos, aumentando a susceptibilidade dos mesmos à erosão. Foram coletados sete perfis de solos, em diferentes posições na paisagem e formados de materiais de origem. As amostras foram secas ao ar e analisados atributos químicos e granulométricos. Os solos estudados apresentam grandes variações em seus atributos morfológicos, químicos e granulométricos, reflexo dos diferentes materiais de origem. A fragilidade em quase todos os perfis é reflexo da incipiência dos solos, representada pelo baixo grau de agregação e coesão entre as partículas, pequena profundidade e o fator de formação relevo induz na maior erosão de cinco dos sete perfis estudados. Os solos frágeis do PNSC necessitam de cuidados especiais quanto ao manejo, pois alguns deles, principalmente os originários de rochas pelíticas da Formação Pimenteiras, encontram-se em forte processo de degradação, em muitas áreas com as rochas expostas. Palavras-chave: Conservação do solo. Classificação de solos. Degradação ambiental. Semiárido tropical. FRAGILE SOILS OF SERRA DA CAPIVARA NATIONAL PARK, PIAUÍ Abstract: The Serra da Capivara National Park (PNSC) are some of the most important archaeological sites in the Americas. The area where the soils were sampled corresponds to the PNSC and a buffer area of 10km around of its official limits in southeastern of Piauí. For this work were considered fragile soils, due to the high risk of degradation by erosion, formed in different geological materials representative of PNSC. All soils are poorly evolved, with pedogenic development incipient fall in orders of Entisols or Inceptisols. The representative of the study area biome is the caatinga, which vegetation with little biomass and deciduous characteristics, gives little coverage to the soil, increasing susceptibility to erosion. Seven soil profiles were collected at different positions and mother rocks. The soils were classified according to the Brazilian System of Soil Classification (SiBCS). The samples were air dried and analyzed the chemical attributes and texture. The soils vary widely in their morphological, chemical and grain size, reflecting the different source material attributes. The weakness in nearly all profiles reflects the incipient soil, represented by a low degree of aggregation and cohesion between the particles of soil and small depth of relief factor induces the formation of further erosion profiles 5 of the 7 studied. Fragile soils of PNSC require special care in the mangement, because some soils, especially those originating from pelitic rocks by Pimenteiras Formation, are in strong degradation process in many areas with exposed rocks. Keywords: Soil conservation. Soil classification. Environmental degradation. Tropical semiarid. SUELOS FRÁGILES DEL PARQUE NACIONAL DE LA SIERRA DE CAPYBARA, PIAUÍ Resumen: El Parque Nacional de la Sierra de Capybara (PNSC) tiene algunos de los sitios arqueológicos más importantes de las Américas. El área donde los suelos fueron muestreados corresponde al PNSC y un área tampón de 10km en el entorno de sus límites oficiales, en el sureste del Piauí. Para la elaboración del presente trabajo se seleccionaron suelos considerados frágiles, debido al alto riesgo de degradación por erosión, formados de diferentes materiales geológicos representativos del PNSC. Todos los suelos estudiados son poco evolucionados, con desarrollo pedogenético aún incipiente, y se encuadran en las órdenes de los Neossolos o Cambissolos (en portugués). El bioma representativo del área de estudio es la caatinga, que por la vegetación con poca biomasa y características deciduas, confiere poca cobertura a los suelos, aumentando la susceptibilidad de los mismos a la erosión. Se recogieron muestras de siete perfiles de suelos, en diferentes posiciones en el paisaje y formados de materiales geológicos distintos. Las muestras fueron secas al aire y analizados los atributos químicos y granulométricos. Los suelos estudiados presentan grandes variaciones en sus atributos morfológicos, químicos y granulométricos, reflejo de los diferentes materiales de origen. La fragilidad en casi todos los perfiles es reflejo de la incipiente de los suelos, representada por el bajo grado de agregación y cohesión entre las partículas, pequeña profundidad y el factor de formación relieve induce en la mayor erosión de cinco de los siete perfiles estudiados. Los suelos frágiles del PNSC necesitan cuidados especiales en cuanto al manejo, pues algunos de ellos, principalmente los originarios de rocas pelíticas de la Formación Pimenteiras, se encuentran en fuerte proceso de degradación, en muchas áreas con las rocas expuestas. Palabras clave: Conservación del suelo. Clasificación de suelos. Degradación ambiental. Semiárido tropical.

Effect of various cations on the initial rate of formation of peroxodisulphates

1980 ◽  
Vol 45 (8) ◽  
pp. 2272-2282 ◽  
Author(s):  
Jan Balej ◽  
Martin Kadeřávek
Keyword(s):  
Sulphuric Acid ◽  
Oxygen Evolution ◽  
Anodic Polarization ◽  
Initial Rate ◽  
Degree Of Conversion ◽  
Polarization Curves ◽  
Mixed Solutions ◽  
Low Degree ◽  
Partial Polarization

Preparation of peroxodisulphates by electrolysis of mixed solutions of sulphuric acid and various sulphates was studied at low degree of conversion; the partial polarization curves of peroxodisulphate formation and of oxygen evolution obtained from the overall anodic polarization curves and current yields of the principal anodic processes were examined. The mechanism of the effect of various cations on the rate of anodic formation of peroxodisulfates is discussed.

Decomposition of hydrogen peroxide on nickel-silver two-component catalyst

1984 ◽  
Vol 49 (10) ◽  
pp. 2222-2230 ◽  
Author(s):  
Viliam Múčka ◽  
Rostislav Silber
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Properties ◽  
Silver Ions ◽  
Surface Concentration ◽  
Chloride Ions ◽  
Nickel Silver ◽  
Silver Catalysts ◽  
Physico Chemical ◽  
Low Degree ◽  
Defective Crystal

The catalytic and physico-chemical properties of low-temperature nickel-silver catalysts with nickel oxide concentrations up to 43.8% (m/m) are examined via decomposition of hydrogen peroxide in aqueous solution. The mixed catalysts prepared at 250°C are composed of partly decomposed silver carbonate or oxide and nickel carbonate or hydroxide decomposed to a low degree only and exhibiting a very defective crystal structure. The activity of these catalysts is determined by the surface concentration of silver ions, which is affected by the nickel component present. The latter also contributes to the thermal stability of the catalytic centres of the silver component, viz. the Ag+ ions. The concentration of these ions varies with the temperature of the catalyst treatment, the activity varies qualitatively in the same manner, and the system approaches the Ag-NiO composition. The catalytic centres are very susceptible to poisoning by chloride ions. A previous exposition of the catalyst to a gamma dose of 10 kGy from a 60Co source has no measurable effect on the physico-chemical properties of the system.

scholarly journals Joint analysis of the magnetic field and Total Gradient Intensity in Central Europe

2019 ◽  
Author(s):  
Maurizio Milano ◽  
Maurizio Fedi ◽  
J. Derek Fairhead
Keyword(s):  
Magnetic Field ◽  
Central Europe ◽  
Joint Analysis ◽  
East European ◽  
Long Wavelength ◽  
Low Degree ◽  
Total Gradient ◽  
Synthetic Models ◽  
The Magnetic Field ◽  
Different Altitudes

Abstract. In the European region, the magnetic field at satellite altitudes (~ 350 km) is mainly defined by a long-wavelength magnetic-low called here the Central Europe Magnetic Low (CEML), located to the southwest of the Trans European Suture Zone (TESZ). We studied this area by a joint analysis of the magnetic and total gradient (∇T) anomaly maps, for a range of different altitudes of 5 km, 100 km and 350 km. Tests on synthetic models showed the usefulness of the joint analysis at various altitudes to identify reverse dipolar anomalies and to characterize areas in which magnetization is weak. By this way we identified areas where either reversely or normally magnetized sources are locally dominant. At a European scale these anomalies are sparse, with a low degree of coalescence effect. The ∇T map indeed presents generally small values within the CEML area, indicating that the Palaeozoic Platform is weakly magnetized. At 350 km altitude, the TESZ effect is largely dominant: with intense ∇T highs above the East European Craton (EEC) and very small values above the Palaeozoic Platform, this again denoting a weakly magnetized crust. Small coalescence effects are masked by the trend of the TESZ. Although we identified sparsely located reversely magnetized sources in the Palaeozoic Platform of the CEML, the joint analysis does not support a model of a generally reversely magnetized crust. Instead, our analysis strongly favors the hypothesis that the CEML anomaly is mainly caused by a sharp contrast between the magnetic properties of EEC and Palaeozoic Platform.

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