Petén
Petén , region, c.15,000 sq mi (38,850 sq km), N Guatemala. A humid expanse of dense, tropical hardwood forests interrupted by savannas and crisscrossed by ranges of hills, it is related geographically to SE Mexico and Belize rather than to the rest of Guatemala. The Usumacinta River system drains most of the region. Rainfall is very heavy. There are large, permanent lakes, notably Lake Petén Itzá. The region is relatively inaccessible and has been only partly developed. It produces lumber, chicle, and some rubber and cacao. The sparse population is mostly Native American. Flores is the chief town.
Once Petén was a center of the Old Empire of the Maya and had a dense agricultural population. It is noted chiefly today as the scene of large-scale excavations of great archaeological ruins, notably Tikal and Uaxactún. Although the Spanish nominally conquered the area and Cortés passed through it on his march to Honduras (1524-25), efforts at subjugation were sporadic until the Itzá tribe was driven out (1697) from their stronghold at Lake Petén Itzá.
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The Viscosities of Foods as Analogs for Silicate Melts
Magazine article from: Journal of Geoscience Education; 9/1/2004; ; 700+ words
; ...comparison with the viscosities of natural...importance of viscosity in igneous...that food viscosities are a useful...INTRODUCTION Viscosity is one of...understanding of magma viscosity. Furthermore...magmas have viscosities so many orders...
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VISCOSITY: The resistance to flow
Magazine article from: Tribology & Lubrication Technology; 8/1/2007; ; 700+ words
; Understanding the importance of viscosity can be analyzed through two concepts...have helped with our understanding of viscosity. Most of us involved in the general lubrication industry know that viscosity, the resistance to flow of a fluid...
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Viscosity ratio effects in the compounding of low viscosity, immiscible fluids into polymeric matrices.
Magazine article from: Polymer Engineering and Science; 6/1/1996; ; 700+ words
; ...large mismatch in the viscosities of low viscosity fluids and molten...reference point. The viscosity ratio, [Lambda...express the relative viscosities of the minor and...8, 9) reported viscosity ratios of approximately...
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Viscosities of lead silicate slags
Magazine article from: Minerals & Metallurgical Processing; 2/1/2002; ; 700+ words
; ...to correlate the viscosities of industrial lead...variation of the slag viscosity is identified...combination of viscosity and melting point...studies on the viscosities of synthetic lead...affect the slag viscosity. Low-order synthetic...cannot reproduce viscosities of industrial ...
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Elongational viscosity of LDPEs and polystyrenes using entrance loss data.(low density polyethylene)(Technical report)
Magazine article from: Polymer Engineering and Science; 2/1/2008; ; 700+ words
; ...elongational flows. Therefore, elongational viscosity of polymers, which characterizes the...first person to measure the elongational viscosity of a fluid. Using various methods such...for axisymmetric flows the elongational viscosity of materials, such as pitch and wax...
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Viscosity of FeO-SiO(2) slags
Magazine article from: Minerals & Metallurgical Processing; 11/1/2001; ; 700+ words
; Abstract The viscosities of various FeO-SiO...derived to relate the viscosity to temperature and the...applied to predict the viscosities of FeO-SiO^sub 2...with the experimental viscosity data. Key words: Iron...
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Viscosity is Only Half the Story
Magazine article from: Tribology & Lubrication Technology; 11/1/2006; ; 700+ words
; ...the performance additive package, the viscosity index of the fluid, and the shear stability of the viscosity index improver used in the fluid The...well known that the proper selection of viscosity index improver (VII). which is used...
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Viscosity of a CaO-MgO-Al2O3-SiO2 melt containg spinel particles at 1646 K
Magazine article from: Metallurgical and Materials Transactions; 2/1/2000; ; 700+ words
; ...the effect of solid suspension on the viscosity of molten slags. Up to about 20 vol...Brookfield DVII+ viscometer was used, The viscosity determined for the solid-free melts...with the results of published work. The viscosity for the solid-containing melt was found...
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Viscosity solution of linear regulator quadratic for degenerate diffusions.
Magazine article from: Journal of Applied Mathematics and Stochastic Analysis; 1/1/2006; ; 700+ words
; ...HJB) equation. We showed the existence of viscosity properties and established a unique viscosity solution of the degenerate HJB equation associated with this problem by the technique of viscosity solutions. 1. Introduction We are concerned...
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Plasma viscosity in diabetic retinopathy.(Article)
Magazine article from: Indian Journal of Ophthalmology; 9/1/1983; ; 700+ words
; ...O. Kulshrestha, Madhu. Mathur The viscosity of blood is considered an important factor...micro circulation. A rise of plasma viscosity is considered to increase the resistance...In this study, estimation of plasma viscosity was done in patients of diabetic retinopathy...
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Viscosity
Encyclopedia entry from: The Gale Encyclopedia of Science
Viscosity The viscosity of a fluid is an internal measure of its resistance to continuous...commonly described as a resistance to pouring of a liquid, such as the viscosity different grades of automobile oil. Thus, it can be described as...
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viscosity
Book article from: The Columbia Encyclopedia, Sixth Edition
viscosity resistance of a fluid to flow. This...fluid itself past stationary obstacles. Viscosity also acts internally on the fluid between...e., all liquids and gases, exhibit viscosity to some degree. Viscosity may be thought...
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mantle convection, plumes, viscosity, and dynamics
Book article from: The Oxford Companion to the Earth
...Using these observations, the viscosity of the mantle is estimated...lower mantle (compared to the viscosity of water which is 10 −3 Pa s). Although the viscosity of the mantle is high, it...geological timescales. Using these viscosities, it is estimated that the...
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Blood-Viscosity Reducing Drugs
Encyclopedia entry from: Gale Encyclopedia of Medicine, 3rd ed.
Blood-Viscosity Reducing Drugs Definition Blood-viscosity reducing drugs are medicines that improve blood flow...viscous (sticky). Purpose The main use of blood-viscosity reducing drugs is to relieve painful leg cramps caused...
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eddy viscosity
Book article from: A Dictionary of Earth Sciences
eddy viscosity A coefficient relating the average shear...vertical gradient of velocity. The eddy viscosity depends on the fluid density and distance...ground surface. The concept of eddy viscosity is fundamental to the von Karman...
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