Results 1  10
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1,379
Trapped surfaces, horizons and exact solutions in higher dimensions
 Class. Quantum Grav
"... Abstract. A very simple criterion to ascertain if (D − 2)surfaces are trapped in arbitrary Ddimensional Lorentzian manifolds is given. The result is purely geometric, independent of the particular gravitational theory, of any field equations or of any other conditions. Many physical applications a ..."
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Cited by 15 (4 self)
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Abstract. A very simple criterion to ascertain if (D − 2)surfaces are trapped in arbitrary Ddimensional Lorentzian manifolds is given. The result is purely geometric, independent of the particular gravitational theory, of any field equations or of any other conditions. Many physical applications
Sulphurcontaining amino acid metabolism in surface horizons of a hardwood forest
 Soil Biol. Biochem
, 1988
"... SummaryThe Ol, O2 and Al horizons of a hardwood forest mineralized and incorporated into organic matter 35 Slabelled cysteine and methionine. Based upon assays of samples collected seasonally during 1 yr (n = 1030), mineralization was the dominant process for cysteine whereas with methionine the ..."
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Cited by 2 (0 self)
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SummaryThe Ol, O2 and Al horizons of a hardwood forest mineralized and incorporated into organic matter 35 Slabelled cysteine and methionine. Based upon assays of samples collected seasonally during 1 yr (n = 1030), mineralization was the dominant process for cysteine whereas with methionine
Natural Enrichment of Trace Elements in Surface Horizons of Calcareous Soils (La Mancha, Spain)
"... The study of five soil profiles developed on carbonatic sediments of Tertiary Miocene origin has been carried out. The topography of the area was basically flat and the traditional uses of the soils are the cultivation of dry cereals and grapevine. The geochemical characterization of the aforementi ..."
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The study of five soil profiles developed on carbonatic sediments of Tertiary Miocene origin has been carried out. The topography of the area was basically flat and the traditional uses of the soils are the cultivation of dry cereals and grapevine. The geochemical characterization of the aforementioned profiles involves a study of the contents of major and trace elements among other pedologic aspects (texture, pH, organic matter, etc.). The results of this study also indicate a superficial enrichment of trace elements due to the leaching of Ca and moderate biological and anthropic activity. We can consider strontium, Sr, as the trace element that characterizes these limy soils (435 mg/kg average content in total soil and 708 mg/kg in the original rock). These contents are similar to the average value in CastillaLa Mancha of 380 mg/kg and are higher than the average in world soils of about 200 mg/kg. High levels of dangerous or pollutant elements (Cd, Hg, Pb, Cu, Zn, or Ni) were not detected. The majority of trace element anomalies are related to calcareous material and the leaching of calcium carbonate (Ca), while the influence of the anthropogenic factor is secondary. Soil quality does not indicate toxicity although surficial enrichment suggests a weak threat from consuming crops.
The gravitational Hamiltonian action, entropy, and surface terms
 Class. Quantum Grav
, 1996
"... We give a general derivation of the gravitational hamiltonian starting from the EinsteinHilbert action, keeping track of all surface terms. The surface term that arises in the hamiltonian can be taken as the definition of the ‘total energy’, even for spacetimes that are not asymptotically flat. (In ..."
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Cited by 162 (3 self)
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We give a general derivation of the gravitational hamiltonian starting from the EinsteinHilbert action, keeping track of all surface terms. The surface term that arises in the hamiltonian can be taken as the definition of the ‘total energy’, even for spacetimes that are not asymptotically flat
The horizon problem for prevalent surfaces
, 2011
"... We investigate the box dimensions of the horizon of a fractal surface defined by a function f ∈ C[0, 1] 2. In particular we show that a prevalent surface satisfies the ‘horizon property’, namely that the box dimension of the horizon is one less than that of the surface. Since a prevalent surface has ..."
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Cited by 3 (2 self)
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We investigate the box dimensions of the horizon of a fractal surface defined by a function f ∈ C[0, 1] 2. In particular we show that a prevalent surface satisfies the ‘horizon property’, namely that the box dimension of the horizon is one less than that of the surface. Since a prevalent surface
Horizon Map Capture
, 2001
"... We present a method for computing horizon maps from captured images of a bumpy surface. Horizon maps encode surface selfshadowing effects, and can be used with bump or normals maps to realistically render surfaces with small height perturbations. The method does not rely on complete surface recon ..."
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Cited by 1 (0 self)
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We present a method for computing horizon maps from captured images of a bumpy surface. Horizon maps encode surface selfshadowing effects, and can be used with bump or normals maps to realistically render surfaces with small height perturbations. The method does not rely on complete surface
The area of horizons and the trapped region
, 2007
"... This paper considers some fundamental questions concerning marginally trapped surfaces, or apparent horizons, in Cauchy data sets for the Einstein equation. An area estimate for outermost marginally trapped surfaces is proved. The proof makes use of an existence result for marginal surfaces, in the ..."
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Cited by 37 (2 self)
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This paper considers some fundamental questions concerning marginally trapped surfaces, or apparent horizons, in Cauchy data sets for the Einstein equation. An area estimate for outermost marginally trapped surfaces is proved. The proof makes use of an existence result for marginal surfaces
Detecting Event Horizons and Stationary Surfaces
, 1998
"... We have investigated the behavior of three curvature invariants for Schwarzschild, ReissnerNordstrøm, Kerr, and KerrNewman black holes. We have also studied these invariants for a Schwarzschildde Sitter spacetime, the γ metric, and for a 2+1 charged dimensional black hole. The invariants are I1 ..."
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= Rαβµν;λR αβµν;λ, I2 = Rµν;λR µν;λ, and I3 = Cαβµν;λC αβµν;λ. For all but the KerrNewman case these invariants serve as either horizon or stationary surface detectors. The KerrNewman case is more complicated. We show that I1 vanishs on the horizon in any spacetime with a Schwarzschild like metric. I.
InterHorizon Variability in PhosphorusSorption
"... Abstract: This study estimated the variability of phosphorus sorption capacity among horizons of highly weathered soils of Otammiri River floodplain in southeastern Nigeria. Four profile pits representing 4 depositional stages of the river were studied. The soils were deep, sandy, acidic and of low ..."
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of epipedal horizons (Ap) while Fe M3 and Al M3 controlled Psorption capacity in the subsurface horizons (AB Bt). Variability among horizons were distributed as follows: Ap (CV = 35%), AB (CV = 25%), Bt 1 (CV = 10%) and Bt 2 (CV = 8%).
Results 1  10
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1,379