1,189 research outputs found
Operator algebra quantum homogeneous spaces of universal gauge groups
In this paper, we quantize universal gauge groups such as SU(\infty), as well
as their homogeneous spaces, in the sigma-C*-algebra setting. More precisely,
we propose concise definitions of sigma-C*-quantum groups and sigma-C*-quantum
homogeneous spaces and explain these concepts here. At the same time, we put
these definitions in the mathematical context of countably compactly generated
spaces as well as C*-compact quantum groups and homogeneous spaces. We also
study the representable K-theory of these spaces and compute it for the quantum
homogeneous spaces associated to the universal gauge group SU(\infty).Comment: 14 pages. Merged with [arXiv:1011.1073
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THERMODYNAMIC TABLES FOR NUCLEAR WASTE ISOLATION, V.1: AQUEOUSSOLUTIONS DATABASE
Tables of consistent thermodynamic property values for nuclear waste isolation are given. The tables include critically assessed values for Gibbs energy of formation. enthalpy of formation, entropy and heat capacity for minerals; solids; aqueous ions; ion pairs and complex ions of selected actinide and fission decay products at 25{sup o}C and zero ionic strength. These intrinsic data are used to calculate equilibrium constants and standard potentials which are compared with typical experimental measurements and other work. Recommendations for additional research are given
Changes in growth of tropical forests: evaluating potential biases
Over the past century almost every ecosystem on Earth has come under the
influence of changes in atmospheric composition and climate caused by human activity.
Tropical forests are among the most productive and extensive ecosystems, and it has been
hypothesized that both the dynamics and biomass of apparently undisturbed, old-growth
tropical forests have been changing in response to atmospheric changes. Long-term forest
sample plots are a critical tool in detecting and monitoring such changes, and our recent
analysis of pan-tropical-forest plot data has suggested that the biomass of tropical forests
has been increasing, providing a modest negative feedback on the rate of accumulation of
atmospheric CO2. However, it has been argued that some of these old forest plot data sets
have significant problems in interpretation because of the use of nonstandardized methodologies.
In this paper we examine the extent to which potential field methodological errors may
bias estimates of total biomass change by detailed examination of tree-by-tree records from
up to 120 Neotropical plots to test predictions from theory. Potential positive biases on
measurements of biomass change include a bias in site selection, tree deformities introduced
by the measurement process, poor methodologies to deal with tree deformities or buttresses,
and nonrecording of negative growth increments. We show that, while it is important to
improve and standardize methodologies in current and future forest-plot work, any systematic
errors introduced by currently identified biases in past studies are small and calculable.
We conclude that most tropical-forest plot data are of useful quality, and that the evidence
does still weigh conclusively in favor of a recent increase of biomass in old-growth tropical
forests
On Parity-Violating Three-Nucleon Interactions and the Predictive Power of Few-Nucleon EFT at Very Low Energies
We address the typical strengths of hadronic parity-violating three-nucleon
interactions in "pion-less" Effective Field Theory in the nucleon-deuteron
(iso-doublet) system. By analysing the superficial degree of divergence of loop
diagrams, we conclude that no such interactions are needed at leading order.
The only two linearly independent parity-violating three-nucleon structures
with one derivative mix two-S and two-P-half waves with iso-spin transitions
Delta I = 0 or 1. Due to their structure, they cannot absorb any divergence
ostensibly appearing at next-to-leading order. This observation is based on the
approximate realisation of Wigner's combined SU(4) spin-isospin symmetry in the
two-nucleon system, even when effective-range corrections are included.
Parity-violating three-nucleon interactions thus only appear beyond
next-to-leading order. This guarantees renormalisability of the theory to that
order without introducing new, unknown coupling constants and allows the direct
extraction of parity-violating two-nucleon interactions from three-nucleon
experiments.Comment: 20 pages LaTeX2e, including 9 figures as .eps file embedded with
includegraphicx. Minor modifications and stylistic corrections. Version
accepted for publication in Eur. Phys. J.
Neutral and cationic half-sandwich arene ruthenium, Cp*Rh and Cp*Ir oximato and oxime complexes: Synthesis, structural, DFT and biological studies
The reaction of [(p-cymene)RuCl2]2 and [Cp*MCl2]2 (M = Rh/Ir) with chelating ligand 2-pyridylcyanoxime {pyC(CN)NOH} leads to the formation of neutral oximato complexes having the general formula [(arene)M{pyC(CN)NO}Cl] {arene = p-cymene, M = Ru, (1); Cp*, M = Rh (2);Cp*, M = Ir (3)}. Whereas the reaction of 2-pyridyl phenyloxime {pyC(Ph)NOH} and 2-thiazolyl methyloxime {tzC(Me)NOH} with precursor compounds afforded the cationic oxide complexes bearing formula [(arene)M{pyC(ph)NOH}Cl]+ and [(arene)M{tzC(Me)NOH}Cl]+{arene = p-cymene M = Ru, (4), (7); Cp*, M = Rh (5), (8); Cp*, M = Ir (6), (9)}. The cationic complexes were isolated as their hexafluorophosphate salts. All these complexes were fully characterized by analytical, spectroscopic and X-ray diffraction studies. The molecular structures of the complexes revealed typical piano stool geometry around the metal center within which the ligand acts as a NNʹ donor chelating ligand. The Chemo-sensitivity activities of the complexes evaluated against HT-29 (human colorectal cancer), and MIAPaCa-2 (human pancreatic cancer) cell line showed that the iridium-based complexes are much more potent than the ruthenium and rhodium analogues. Theoretical studies were carried out to have a deeper understanding about the charge distribution pattern and the various electronic transitions occurring in the complexes
Hall Conductivity near the z=2 Superconductor-Insulator Transition in 2D
We analyze here the behavior of the Hall conductivity near a
insulator-superconductor quantum critical point in a perpendicular
magnetic field. We show that the form of the conductivity is sensitive to the
presence of dissipation , and depends non-monotonically on once
is weak enough. passes through a maximum at in the quantum critical regime, suggesting that the limits and
do not commute.Comment: 4 pages, 1 .eps figure, to appear in Phys. Rev.
Parity-violating asymmetry in with a pionless effective theory
Nuclear parity violation is studied with polarized neutrons in the
photodisintegration of the deuteron at low energies. A pionless effective field
theory with di-baryon fields is used for the investigation. Hadronic weak
interactions are treated by parity-violating di-baryon-nucleon-nucleon
vertices, which have undetermined coupling contants. A parity-violating
asymmetry in the process is calculated for the incident photon energy up to 30
MeV. If experimental data for the parity-violating asymmetry become available
in the future, we will be able to determine the unknown coupling contants in
the parity-violating vertices.Comment: 4 pages. A contribution to APFB2011, August 22-26, 2011, Seoul, Kore
Very High Resolution Solar X-ray Imaging Using Diffractive Optics
This paper describes the development of X-ray diffractive optics for imaging
solar flares with better than 0.1 arcsec angular resolution. X-ray images with
this resolution of the \geq10 MK plasma in solar active regions and solar
flares would allow the cross-sectional area of magnetic loops to be resolved
and the coronal flare energy release region itself to be probed. The objective
of this work is to obtain X-ray images in the iron-line complex at 6.7 keV
observed during solar flares with an angular resolution as fine as 0.1 arcsec -
over an order of magnitude finer than is now possible. This line emission is
from highly ionized iron atoms, primarily Fe xxv, in the hottest flare plasma
at temperatures in excess of \approx10 MK. It provides information on the flare
morphology, the iron abundance, and the distribution of the hot plasma.
Studying how this plasma is heated to such high temperatures in such short
times during solar flares is of critical importance in understanding these
powerful transient events, one of the major objectives of solar physics. We
describe the design, fabrication, and testing of phase zone plate X-ray lenses
with focal lengths of \approx100 m at these energies that would be capable of
achieving these objectives. We show how such lenses could be included on a
two-spacecraft formation-flying mission with the lenses on the spacecraft
closest to the Sun and an X-ray imaging array on the second spacecraft in the
focal plane \approx100 m away. High resolution X-ray images could be obtained
when the two spacecraft are aligned with the region of interest on the Sun.
Requirements and constraints for the control of the two spacecraft are
discussed together with the overall feasibility of such a formation-flying
mission
Existence of superposition solutions for pulse propagation in nonlinear resonant media
Existence of self-similar, superposed pulse-train solutions of the nonlinear,
coupled Maxwell-Schr\"odinger equations, with the frequencies controlled by the
oscillator strengths of the transitions, is established. Some of these
excitations are specific to the resonant media, with energy levels in the
configurations of and and arise because of the interference
effects of cnoidal waves, as evidenced from some recently discovered identities
involving the Jacobian elliptic functions. Interestingly, these excitations
also admit a dual interpretation as single pulse-trains, with widely different
amplitudes, which can lead to substantially different field intensities and
population densities in different atomic levels.Comment: 11 Pages, 6 Figures, presentation changed and 3 figures adde
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