7,398 research outputs found
Oxidation of Monolayers of Partly Converted Dimethoxy-Substituted Poly(p-phenylenevinylene) Precursor Polymers at the Air-Water Interface
We observed that the poly(p-phenylenevinylene) units in Langmuir monolayers of partly converted dimethoxy-substituted poly(p-phenylenevinylene) precursor polymers oxidize at the air-water interface. This reaction even happened in the dark and therefore can not be attributed to a photooxygenation reaction with singlet oxygen. We assume that ground-state triplet oxygen is polarized at the air-water interface and forms a weakly bound complex with the double bond to give a reactive intermediate state, which lowers the activation energy of the oxidation reaction. The air-water interface thus works as a catalyst in this reaction.
ATLAS Jet Energy Scale
Jets originating from the fragmentation of quarks and gluons are the most
common, and complicated, final state objects produced at hadron colliders. A
precise knowledge of their energy calibration is therefore of great importance
at experiments at the Large Hadron Collider at CERN, while is very difficult to
ascertain. We present in-situ techniques and results for the jet energy scale
at ATLAS using recent collision data. ATLAS has demonstrated an understanding
of the necessary jet energy corrections to within \approx 4% in the central
region of the calorimeter.Comment: Proceedings from XXXI Physics in Collisio
Resonance saturation in the odd-intrinsic parity sector of low-energy QCD
Using the large N_C approximation we have constructed the most general chiral
resonance Lagrangian in the odd-intrinsic parity sector that can generate low
energy chiral constants up to O(p^6). Integrating out the resonance fields
these O(p^6) constants are expressed in terms of resonance couplings and
masses. The role of eta' is discussed and its contribution is explicitly
factorized. Using the resonance basis we have also calculated two QCD Green
functions of currents: and and found, imposing high energy
constraints, additional relations for resonance couplings. We have studied
several phenomenological implications based on these correlators from which let
us mention here our prediction for the pi0-pole contribution to the muon g-2
factor: .Comment: 42 pages, 3 figure
Variability of fundamental constants
If the fine structure constant is not really constant, is this due to a
variation of , , or ? It is argued that the only reasonable
conclusion is a variable speed of light.Comment: preliminary draft, comments welcom
Commuting symmetry operators of the Dirac equation, Killing-Yano and Schouten-Nijenhuis brackets
In this paper we derive the most general first-order symmetry operator
commuting with the Dirac operator in all dimensions and signatures. Such an
operator splits into Clifford even and Clifford odd parts which are given in
terms of odd Killing-Yano and even closed conformal Killing-Yano inhomogeneous
forms respectively. We study commutators of these symmetry operators and give
necessary and sufficient conditions under which they remain of the first-order.
In this specific setting we can introduce a Killing-Yano bracket, a bilinear
operation acting on odd Killing-Yano and even closed conformal Killing-Yano
forms, and demonstrate that it is closely related to the Schouten-Nijenhuis
bracket. An important non-trivial example of vanishing Killing-Yano brackets is
given by Dirac symmetry operators generated from the principal conformal
Killing-Yano tensor [hep-th/0612029]. We show that among these operators one
can find a complete subset of mutually commuting operators. These operators
underlie separability of the Dirac equation in Kerr-NUT-(A)dS spacetimes in all
dimensions [arXiv:0711.0078].Comment: 37 pages, no figure
Determinants of species richness patterns in the Netherlands across multiple taxonomic groups
We examined the species richness patterns of five different species groups (mosses, reptiles and amphibians, grasshoppers and crickets, dragonflies, and hoverflies) in the Netherlands (41,500 km2) using sampling units of 5 × 5 km. We compared the spatial patterns of species richness of the five groups using Spearman¿s rank correlation and used a stepwise multiple regression generalized linear modelling (GLM) approach to assess their relation with a set of 36 environmental variables, selected because they can be related to the several hypotheses on biodiversity patterns. Species richness patterns of the five groups were to a certain extent congruent. Our data suggest that environmental heterogeneity (in particular habitat heterogeneity) is one of the major determinants of variation in species richness within these five groups. We found that for taxonomic groups comprising a low number of species, our regression model explained more of the variability in species richness than for taxonomic groups with a large number of specie
Not So Meaningful Anymore: Why a Law Library Is Required to Make a Prisoner\u27s Access to the Courts Meaningful
Ready to Eat Nectarines - Assuring Quality in the Chain
Time-resolved reflectance spectroscopy, coupled to the modelling of firmness decrease, was used to predict at harvest softening behaviour of nectarines. Selected fruit were used in an export trial from Italy to The Netherlands. Quality assessed after shelf life was in agreement with the predicted firmness for fruit of different stages of maturity, showing that it is possible to select fruit at harvest for different market destinations and prevent transportation of fruit unsuitable for consumption
Dualities between Poisson brackets and antibrackets
Recently it has been shown that antibrackets may be expressed in terms of
Poisson brackets and vice versa for commuting functions in the original
bracket. Here we also introduce generalized brackets involving higher
antibrackets or higher Poisson brackets where the latter are of a new type. We
give generating functions for these brackets for functions in arbitrary
involutions in the original bracket. We also give master equations for
generalized Maurer-Cartan equations. The presentation is completely symmetric
with respect to Poisson brackets and antibrackets.Comment: 24 pages,Latexfile,corrected (2.7-8) and removed text between (2.9)
and (2.10
- …