423 research outputs found
Fate and occurrence of alkylphenolic compounds in sewage sludges determined by liquid chromatography tandem mass spectrometry
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2009 Taylor & Francis.An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solidâphase extraction prior to determination by liquid chromatography tandem mass spectrometry. The recoveries, determined by spiking sewage sludge at two concentrations, ranged from 51% to 89% with method detection limits from 6 ”g kgâ1 to 60 ”g kgâ1. The methodology was subsequently applied to sludge samples obtained from a carbonaceous activated sludge plant, a nitrifying/denitrifying activated sludge plant and a nitrifying/denitrifying activated sludge plant with phosphorus removal. Concentrations of nonylphenolic compounds were two to three times higher than their octyl analogues. Longâchain nonylphenol polyethoxylates (NP3â12EO) ranged from 16 ”g kgâ1 to 11754 ”g kgâ1. The estrogenic metabolite nonylphenol was present at concentrations ranging from 33 ”g kgâ1 to 6696 ”g kgâ1.Public Utilities Board of Singapore, Thames Water and Yorkshire Water
Entanglement of photons
It is argued that the title of this paper represents a misconception.
Contrary to widespread beliefs it is electromagnetic field modes that are
``systems'' and can be entangled, not photons. The amount of entanglement in a
given state is shown to depend on redefinitions of the modes; we calculate the
minimum and maximum over all such redefinitions for several examples.Comment: 5 pages ReVTe
Dynamics of Entanglement in One-Dimensional Spin Systems
We study the dynamics of quantum correlations in a class of exactly solvable
Ising-type models. We analyze in particular the time evolution of initial Bell
states created in a fully polarized background and on the ground state. We find
that the pairwise entanglement propagates with a velocity proportional to the
reduced interaction for all the four Bell states. Singlet-like states are
favored during the propagation, in the sense that triplet-like states change
their character during the propagation under certain circumstances.
Characteristic for the anisotropic models is the instantaneous creation of
pairwise entanglement from a fully polarized state; furthermore, the
propagation of pairwise entanglement is suppressed in favor of a creation of
different types of entanglement. The ``entanglement wave'' evolving from a Bell
state on the ground state turns out to be very localized in space-time. Further
support to a recently formulated conjecture on entanglement sharing is given.Comment: 25 pages, 21 figures; revte
A Thermal Graviton Background from Extra Dimensions
Inflationary cosmology predicts a low-amplitude graviton background across a
wide range of frequencies. This Letter shows that if one or more extra
dimensions exist, the graviton background may have a thermal spectrum instead,
dependent on the fundamental scale of the extra dimensions. The energy density
is shown to be significant enough that it can affect nucleosynthesis in a
substantial way. The possibility of direct detection of a thermal graviton
background using the 21-cm hydrogen line is discussed. Alternative explanations
for the creation of a thermal graviton background are also examined.Comment: 5 pages, 1 figure, requires autart.cls, to appear in Phys. Lett. B, 1
reference adde
Spin-gravity coupling and gravity-induced quantum phases
External gravitational fields induce phase factors in the wave functions of
particles. The phases are exact to first order in the background gravitational
field, are manifestly covariant and gauge invariant and provide a useful tool
for the study of spin-gravity coupling and of the optics of particles in
gravitational or inertial fields. We discuss the role that spin-gravity
coupling plays in particular problems.Comment: 18 pages, 1 figur
Emotion, Meaning, and Appraisal Theory
According to psychological emotion theories referred to as appraisal
theory, emotions are caused by appraisals (evaluative judgments). Borrowing a term from Jan Smedslund, it is the contention of this article that psychological appraisal theory is âpseudoempiricalâ (i.e., misleadingly or incorrectly empirical). In the article I outline what makes some scientific psychology âpseudoempirical,â distinguish my view on this from Jan Smedslundâs, and then go on to show why paying heed to the ordinary meanings of emotion terms is relevant to psychology, and how appraisal theory is methodologically off the mark by
employing experiments, questionnaires, and the like, to investigate what follows from the ordinary meanings of words. The overarching argument of the article is that the scientific research program of appraisal theory is fundamentally misguided and that a more philosophical approach is needed to address the kinds of questions it seeks to answer
Level models of continuing professional development evaluation: a grounded review and critique
Continuing professional development (CPD) evaluation in education has been heavily influenced by âlevel modelsâ, deriving from the work of Kirkpatrick and Guskey in particular, which attempt to trace the processes through which CPD interventions achieve outcomes. This paper considers the strengths and limitations of such models, and in particular the degree to which they are able to do justice to the complexity of CPD and its effects. After placing level models within the broader context of debates about CPD evaluation, the paper reports our experience of developing such models heuristically for our own evaluation practice. It then draws on positivist, realist and constructivist traditions to consider some more fundamental ontological and epistemological questions to which they give rise. The paper concludes that level models can be used in a number of ways and with differing emphases, and that choices made about their use will need to reflect both theoretical choices and practical considerations
Generation of Primordial Cosmological Perturbations from Statistical Mechanical Models
The initial conditions describing seed fluctuations for the formation of
structure in standard cosmological models, i.e.the Harrison-Zeldovich
distribution, have very characteristic ``super-homogeneous'' properties: they
are statistically translation invariant, isotropic, and the variance of the
mass fluctuations in a region of volume V grows slower than V. We discuss the
geometrical construction of distributions of points in with similar
properties encountered in tiling and in statistical physics, e.g. the Gibbs
distribution of a one-component system of charged particles in a uniform
background (OCP). Modifications of the OCP can produce equilibrium correlations
of the kind assumed in the cosmological context. We then describe how such
systems can be used for the generation of initial conditions in gravitational
-body simulations.Comment: 7 pages, 3 figures, final version with minor modifications, to appear
in PR
The Glass-like Universe: Real-space correlation properties of standard cosmological models
After reviewing the basic relevant properties of stationary stochastic
processes (SSP), defining basic terms and quantities, we discuss the properties
of the so-called Harrison-Zeldovich like spectra. These correlations, usually
characterized exclusively in k-space (i.e. in terms of power spectra P(k)), are
a fundamental feature of all current standard cosmological models. Examining
them in real space we note their characteristics to be a {\it negative} power
law tail \xi(r) \sim - r^{-4} and a {\it sub-poissonian} normalised variance in
spheres \sigma^2(R) \sim R^{-4} \ln R. We note in particular that this latter
behaviour is at the limit of the most rapid decay (\sim R^{-4}) of this
quantity possible for any stochastic distribution (continuous or discrete).
This very particular characteristic is usually obscured in cosmology by the use
of Gaussian spheres. In a simple classification of all SSP into three
categories, we highlight with the name ``super-homogeneous'' the properties of
the class to which models like this, with P(0)=0, belong. In statistical
physics language they are well described as glass-like. They do not have either
``scale-invariant'' features, in the sense of critical phenomena, nor fractal
properties. We illustrate their properties with some simple examples, in
particular that of a ``shuffled'' lattice.Comment: 20 pages, 3 postscript figures, corrected some typos and minor
changes to match the accepted version in Physical Review
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