نتایج جستجو برای: serpentine
تعداد نتایج: 1871 فیلتر نتایج به سال:
This report describes a case of a serpentine fusiform aneurysm of the internal carotid artery in a patient who presented with visual disturbances. The serpentine aneurysm was treated successfully by coil trapping and occlusion of the parent artery, accompanied by balloon dilation. Nine months post-operatively, the patient's visual acuity had improved considerably.
Grazing and fire and are major forces shaping patterns of native and exotic species diversity in many grasslands, yet both of these disturbances have notoriously variable effects. Few studies have examined how landscape-level heterogeneity in grassland characteristics, such as soil-based variation in biomass and species composition, may contribute to variation in the effects of fire or grazing....
PURPOSE To describe the characteristic CT, MR, and angiographic features of giant serpentine aneurysms and discuss their endovascular treatment. METHODS Thirteen patients with giant serpentine aneurysms were studied at our institution in the last 3 years. They all underwent CT and MR studies as well as cerebral angiography. More recently, some of the patients were studied with MR angiography....
BACKGROUND AND AIMS Serpentine soils provide a highly selective substrate for plant colonization and growth and represent an ideal system for studying the evolution of plant-ecotypes. In the present study the aim was to identify the genetic architecture of morphological traits distinguishing serpentine and non-serpentine ecotypes of Silene vulgaris. METHODS Using an F(2) mapping population de...
ultramafic rocks are essentially constituted by silicates of magnesium: forsterite, and/or diopside-enstatite; who’s the most common hydrothermal alteration are the serpentinization. to bou azzer, the serpentinisation affected almost all of the ultrabasic rocks. among the phenomena bound to the serpentinisation observed on the ground, we distinguish the magnesium deposits (carbonated serpentini...
Plant specialization on soils derived from unusual parent materials is an important contributor to regional biodiversity. These stressful substrates include serpentine, gabbro, and other ultramafic rocks rich in heavy metals. The effect of substrate on plant diversity is illustrated by serpentine soils in California: they comprise less than 1% of the surface of the state (1), but serpentine end...
The shock equation of state of serpentine has been determined to 150 GPa. Four distinct regions occur along the Hugoniot: a low-pressure phase, a mixed phase region, a high-pressure phase, and a very high pressure phase. The low-pressure phase (LPP) exists under shock pressures to about 40 GPa. This material exhibits shock properties that are partially consistent with those of low pressure serp...
Serpentine soils represent stressful habitats where plants have to cope with heavy metals, moisture limitation and low nutrient availability. We propose that facilitation is an important mechanism structuring plant communities under such stressful conditions. Facilitation has been shown to generate the spatial association of species, forming discrete vegetation patches of phylogenetically dista...
Surface soils of Sabzevar zone could be geochemically divided into two groups of serpentine (Se) and non-serpentine (Nse) soils. Serpentine soils have higher MgO, FeOt, CaO, S, Ag, Co, Cr, Cu and Ni and lower SiO2, Al2O3, Na2O, K2O, Be, Li, Sc, Ti, U and V than Nse. In other word, Nse samples have high REE content with fractionated LREE/HREE trends in REE diagrams (ΣREE= 31.89- 58.3 ppm; LaN/Yb...
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