20,263 research outputs found
Creating Momentum: The Atlantic Philanthropies' Investments to Repeal the Death Penalty in the United States
The Atlantic Philanthropies invested about $60 million between 2004 and 2016 to support efforts to repeal the death penalty in the United States. To assess the effectiveness of this work and to generate lessons for human rights activists and other funders involved in the repeal movement, the foundation commissioned this evaluation. The findings contained in this report are the result of extensive documentation review as well as interviews with foundation and grantee board and staff
Excitations of the Fractional Quantum Hall State and the Generalized Composite Fermion Picture
We present a generalization of the composite Fermion picture for a
muticomponent quantum Hall plasma which contains particle with different
effective charges. The model predicts very well the low-lying states of a
quantum Hall state found in numerical diagonalization.Comment: 5 pages, 3 figure
Fractional quantum Hall effect and electron correlations in partially filled first excited Landau level
We present a quantitative study of most prominent incompressible quantum Hall
states in the partially filled first excited Landau level (LL1) which have been
recently studied experimentally by Choi et al. The pseudopotential describing
the electron - electron interaction in LL1 is harmonic at short range. It
produces a series of incompressible states which is different from its LL0
counterpart. The numerical data indicate that the most prominent states
, 7/3, and 8/3 are not produced by Laughlin correlated electrons,
but result from a tendency of electrons to form pairs or larger clusters which
eventually become Laughlin correlated. States with smaller gaps at filling
factors 14/5, 16/7, 11/5, 19/7 are Laughlin correlated electron or hole states
and fit Jain's sequence of filled levels.Comment: 4 pages, 7 figure
X-ray Amorphous Components of Antarctica Dry Valley Soils: Weathering Implications for Mars
The Antarctic Dry Valleys (ADV) comprise the largest ice-free region of Antarctica. Precipitation usually occurs as snow, relative humidity is frequently low, and mean annual temperatures are about -20C [1]. Substantial work has focused on soil formation in the ADVs [2], however, little work has focused on the mineralogy of secondary alteration phases. The dominant weathering process in the ADV region is physical weathering, however, chemical weathering has been well documented [3]. The occurrence of chemical weathering processes are suggested by the presence of clay minerals and iron and titanium oxides in soil. Previously we have investigated soils from two sites in the ADVs and have shown evidence of chemical weathering by the presence of clay minerals (vermiculite, smectite), short-range ordered (SRO) and/or X-ray amorphous materials, and Fe- and Tioxides as well as the presence of discrete calcite crystals [4, 5]. The Chemistry and Mineralogy (CheMin) instrument onboard the Mars Curiosity rover has detected abundant amounts (approx. 25-30 wt. %) of X-ray amorphous materials in a windblown deposit or soil (Rocknest) and in a sedimentary rocks [6,7,8]. The occurrence of large amounts of X-ray amorphous materials in Mars sediments is surprising because these materials are usually present in small quantities in terrestrial environments. The objective of this study is to further characterize the chemistry and mineralogy, specifically the secondary alteration mineralogy and the presence of X-ray amorphous material, of soils from two sites we have previously studied, a subxerous soil in Taylor Valley, and an ultraxerous soil in University Valley. While the chemical alteration processes and mineralogy of the ADV has been documented previously, there has been limited discussion on the occurrence and formation of X-ray amorphous and SRO materials in Antarctica soils. The process of aqueous alteration in the ADVs may have implications for pedogenic processes on Mars, and may lead to a better understanding to the abundance of amorphous material found in sediments in Gale crater
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