Colorado State University

About: Colorado State University is a education organization based out in Fort Collins, Colorado, United States. It is known for research contribution in the topics: Population & Radar. The organization has 31430 authors who have published 69040 publications receiving 2724463 citations. The organization is also known as: CSU & Colorado Agricultural College.

Metal Nanotubule Membranes with Electrochemically Switchable Ion-Transport Selectivity

Abstract: Membranes containing cylindrical metal nanotubules that span the complete thickness of the membrane are described. The inside radius of the nanotubules can be varied at will; nanotubule radii as small as 0.8 nanometer are reported. These membranes show selective ion transport analogous to that observed in ion-exchange polymers. Ion permselectivity occurs because excess charge density can be present on the inner walls of the metal tubules. The membranes reject ions with the same sign as the excess charge and transport ions of the opposite sign. Because the sign of the excess charge on the tubule can be changed potentiostatically, a metal nanotubule membrane can be either cation selective or anion selective, depending on the potential applied to the membrane.

Orthogonal Cultural Identification Theory: The Cultural Identification of Minority Adolescents

Abstract: A theory of cultural identification is presented indicating that identification with different cultures is orthogonal. Instead of cultures being placed at opposite ends of a continuum, cultural identification dimensions are independent of each other, and increasing identification with one culture does not require decreasing identification with another. Studies of Native-American and Mexican-American youth show that: (1) identification with Anglo (White American) culture is related to having Anglo friends and to family acceptance of an Anglo marriage, (2) identification with either the minority or the majority culture is a source of personal and social strength, and (3) this greater strength, however, does not translate automatically into less drug use, because drug use is related to how much the culture that the person identifies with approves or disapproves of drugs. [Translations are provided. See the International Abstracts at the end of the issue.]

Why do tree species affect soils? The Warp and Woof of tree-soil interactions

Abstract: Many ideas have been advanced regarding how trees affect soils. Enough evidence is now available to evaluate the strength of these ideas and to consider interactions between tree species and soils in an evolutionary context. Forest floor mass commonly differs by about 20% for different species growing on the same site; differences of up to 5-fold have been reported. Litterfall mass and N content commonly differ by 20 to 30%, but larger differences are also common (especially with N-fixing species). The net mineralizaton of soil N typically differs by 50% or more among species, indicating very strong feedback possibilities. We evaluate the evolutionary context of tree effects on soils by considering 3 degrees of coupling of trees to soils: tightly woven connections where the fitness of the tree is enhanced by its effect on soils; loosely woven interactions where selection for tree fitness unrelated to soil properties leads to indirect effects on soils (either enhancing or impairing fitness); and frayed interactions where the effects of trees on soil derive from features of the ecosystem that do not involve direct selection for tree fitness. Evidence supports each of these degrees of interaction for at least some cases, and no single context explains all the interactions between trees and soils. Important areas for further work include: next-generation assessments of the effects of trees on soil suitability for the same (and different) species, and the role of soil organisms in developing and modifying the effects of trees on soils.