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71.
John Lott 《K-Theory》2005,34(4):283-326
The fundamental group of a hyperbolic manifold acts on the limit set, giving rise to a cross-product C*-algebra. We construct nontrivial K-cycles for the cross-product algebra, thereby extending some results of Connes and Sullivan
to higher dimensions. We also show how the Patterson–Sullivan measure on the limit set can be interpreted as a center-valued
KMS state. 相似文献
72.
The procedure described in this paper can be used to determine trace amounts of nitrilotriacetic acid (NTA) in tap water samples with a relative standard deviation of 10% or less. The procedure does not use expensive equipment, is relatively fast and can be used for routine determination of NTA. 相似文献
73.
A procedure for the detection of gunshot residue via the organic constituent diphenylamine is described. The method incorporates high-performance liquid chromatography with electrochemical detection. 相似文献
74.
75.
Barnette JE Lott MJ Howa JD Podlesak DW Ehleringer JR 《Rapid communications in mass spectrometry : RCM》2011,25(10):1422-1428
Hydrogen peroxide (H(2)O(2)) is a widely used oxidizer with many commercial applications; unfortunately, it also has terrorist-related uses. We analyzed 97 hydrogen peroxide solutions representing four grades purchased across the United States and in Mexico. As expected, the range of hydrogen (δ(2)H, 230‰) and oxygen (δ(18)O, 24‰) isotope values of the H(2)O(2) solutions was large, reflecting the broad isotopic range of dilution waters. This resulted in predictable linear relationships of δ(2)H and δ(18)O values of H(2)O(2) solutions that were near parallel to the Meteoric Water Line (MWL), offset by the concentration of H(2)O(2) in the solution. By grade, dilute (3 to 35%) H(2)O(2) solutions were not statistically different in slope. Although the δ(2)H values of manufactured H(2)O(2) could be different from those of water, rapid H(2)O(2)-H(2)O exchange of H atoms eliminated any distinct isotope signal. We developed a method to measure the δ(18)O value of H(2)O(2) independent of dilution water by directly measuring O(2) gas generated from a catalase-induced disproportionation reaction. We predicted that the δ(18)O values of H(2)O(2) would be similar to that of atmospheric oxygen (+23.5‰), the predominant source of oxygen in the most common H(2)O(2) manufacturing process (median disproportionated δ(18)O=23.8‰). The predictable H-O relationships in H(2)O(2) solutions make it possible to distinguish commercial dilutions from clandestine concentration practices. Future applications of this work include synthesis studies that investigate the chemical link between H(2)O(2) reagents and peroxide-based explosive products, which may assist law enforcement in criminal investigations. 相似文献
76.
RosaM. Claramunt Concepcin Lpez Susanne Lott M.Dolores SantaMaría Ibon Alkorta Jos Elguero 《Helvetica chimica acta》2005,88(7):1931-1942
The tautomerism of the enol form of acetylacetone (=pentane‐2,4‐dione; 1 ) inside a host cavity has been studied by means of solid‐state 13C‐NMR spectroscopy (SSNMR) using the variable‐temperature CPMAS technique. It appears that the enol form, 4‐hydroxypent‐3‐en‐2‐one ( 1a ), exists in an equilibrium with an identical tautomer ( 1c ) trough O H ⋅⋅⋅O proton transfer. The experimental results (energy barrier and chemical shifts) were rationalized by means of MP2 and GIAO calculations. 相似文献
77.
The high-frequency modulation characteristics of GaAs-based bipolar cascade vertical cavity surface-emitting lasers operating at 980 nm with GaAs tunnel junctions and p-doped Al0.98Ga0.02As oxide apertures have been measured. We achieve -3 dB laser output modulations of 6.5 GHz for two-stage and 9.4 GHz for three-stage devices in response to small-signal current injection at an operating temperature of -50 degrees C. 相似文献
78.
Rose M. Pringle Katie Milton Brkich Thomasenia Lott Adams Cirecie West‐Olatunii Diane A. Archer‐Banks 《School science and mathematics》2012,112(4):217-229
Despite recent progress toward gender equity in science and mathematics education, the underachievement of low‐income African American girls remains a challenge when compared with their white counterparts. Furthermore, the causes of this persistent underachievement have not been explored thoroughly. We have initiated a three‐year longitudinal study of how African American girls position themselves in relation to science and mathematics learning from fifth to seventh grade, including the impact, if any, of the positioning of teachers, counselors, and parents on this process. In this article, we share findings examining science and mathematics teachers' actions and perceptions and their positioning of African American girls. This qualitative study used an interpretive design with multiple data sources including classroom observations, interviews, and field notes. Findings reveal that school‐wide policies and teachers' autonomous decisions impact the regularity of science and mathematics instruction, and that teachers do not always conceptualize the girls as science and mathematics achievers, positioning them in negative ways. 相似文献
79.
Let be a lattice in a connected Lie group. We show that, besidesa few exceptional cases, the deficiency of is nonpositive.1991 Mathematics Subject Classification 20F05. 相似文献
80.
V. A. Ukleev N. A. Grigorieva A. A. Vorobiev S. V. Grigoriev L. V. Lutsev E. A. Dyadkina D. Lott A. I. Stognii N. N. Novitsky 《Physics of Particles and Nuclei Letters》2011,8(10):1054-1055
Using the polarized neutron reflectometry method, we studied Au/SiO2 + Co(60 at %)/GaAs granular films, which display a giant injection magnetoresistance effect in a narrow temperature range close to T = 300 K. We revealed the existence of a layer having particular magnetic properties at the boundary of a film with a semiconductor GaAs substrate. Experiments carried out at temperatures T = 300 K and T = 100 K showed an insignificant difference in the magnetic profile of the heterostructure. 相似文献