1,528 research outputs found
Metal complexes as potential ligands : the deprotonation of aminephenolate metal complexes
The cationic nickel, copper and zinc complexes of tris-(2-hydroxybenzyl)-aminoethylamine (H6TrenSal) have been deprotonated using potassium hydroxide. The nickel complex can be sequentially deprotonated to form a series of compounds namely, [(H6TrenSal)Ni]+, [(H6TrenSal)Ni] and "[(H6TrenSal)Ni]K". The latter is isolated as a mixture of species namely [{(H6TrenSal)Ni}K(EtOH)]2, [{(H6TrenSal)Ni}K(EtOH)2-μ-OH2]2 and [{(H6TrenSal)Ni}K(EtOH)2-μ-EtOH]2, which co-crystallise in a roughly 50:27.5:22.5 ratio. In contrast the deprotonation of [(H6TrenSal)M]+ (M = Cu, Zn) results in the formation of tetrameric complexes [({(H6TrenSal)Ni}K(OH2)2)4(μ4-OH2)]
LIVESTOCK AND POULTRY PRODUCTION RISK IN THE UNITED STATES
Livestock Production/Industries,
Large Scale Inhomogeneity Versus Source Evolution -- Can We Distinguish Them Observationally?
We reconsider the issue of proving large scale spatial homogeneity of the
universe, given isotropic observations about us and the possibility of source
evolution both in numbers and luminosities. Two theorems make precise the
freedom available in constructing cosmological models that will fit the
observations. They make quite clear that homogeneity cannot be proven without
either a fully determinate theory of source evolution, or availability of
distance measures that are independent of source evolution. We contrast this
goal with the standard approach that assumes spatial homogeneity a priori, and
determines source evolution functions on the basis of this assumption.Comment: mn style, mn.sty file included, mn.sty file remove
Partially locally rotationally symmetric perfect fluid cosmologies
We show that there are no new consistent cosmological perfect fluid solutions
when in an open neighbourhood of an event the fluid kinematical
variables and the electric and magnetic Weyl curvature are all assumed
rotationally symmetric about a common spatial axis, specialising the Weyl
curvature tensor to algebraic Petrov type D. The consistent solutions of this
kind are either locally rotationally symmetric, or are subcases of the Szekeres
dust models. Parts of our results require the assumption of a barotropic
equation of state. Additionally we demonstrate that local rotational symmetry
of perfect fluid cosmologies follows from rotational symmetry of the Riemann
curvature tensor and of its covariant derivatives only up to second order, thus
strengthening a previous result.Comment: 20 pages, LaTeX2.09 (10pt), no figures; shortened revised version,
new references; accepted for publication in Classical and Quantum Gravit
Stability Criteria for SIS Epidemiological Models under Switching Policies
We study the spread of disease in an SIS model. The model considered is a
time-varying, switched model, in which the parameters of the SIS model are
subject to abrupt change. We show that the joint spectral radius can be used as
a threshold parameter for this model in the spirit of the basic reproduction
number for time-invariant models. We also present conditions for persistence
and the existence of periodic orbits for the switched model and results for a
stochastic switched model
Estimating the Benefits of Beach Recreation: An Application of the Contingent Valuation Method
This study presents an application of the dichotomous choice contingent valuation method to estimate the
benefits of beach recreation in Port Dickson. The logit and probit models were used to analyse the data and
the willingness-to-pay values were computed from the maximum likelihood estimates. The median willingnessto-
pay value for beach recreation in Port Dickson ranged from RM55.01 to RM534.80 for mean income of
RM404.56 to RM3933.30, respectively. These values can be used by policy-makers to compute the annual total
benefits obtainable from this multiple-use resource
Green and Sustainable Development for TVET in Asia
Green paradigm is emerging in Asia. In order to achieve sustainability, embracing green paradigm is critical. The growing significance of sustainability is having a major impact on business, industry, and society as a whole. Hence, preparing the future workforce for the coming green economy is a challenging task for many Asian countries especially in Technical and Vocational Education and Training (TVET) in the post-2015 agenda. As a ground work, transforming TVET in Asia to meet the challenges of the green economy for the purpose of sustainability should begin now. The aim of this paper is to map the sustainable development in terms of green mindset, lifestyle, economy, education, training, employability and sustainability in selected Asian countries. A country's quantum leap or leap-frogging in sustainable economy is dependent of its transformation of human resources especially in TVET sector. Thus, TVET should be transformed to fit the requirements of the sustainable green paradigm. The results posit the country's policies, best practices, and challenges toward green economy in order to achieve sustainable development. Finally, the implication of green paradigm on TVET system in selected countries in the Asia Pacific will be discussed
Spot deformation and replication in the two-dimensional Belousov-Zhabotinski reaction in water-in-oil microemulsion
In the limit of large diffusivity ratio, spot-like solutions in the
two-dimensional Belousov-Zhabotinski reaction in water-in-oil microemulsion are
studied. It is shown analytically that such spots undergo an instability as the
diffusivity ratio is decreased. An instability threshold is derived. For spots
of small radius, it is shown that this instability leads to a spot splitting
into precisely two spots. For larger spots, it leads to deformation, fingering
patterns and space-filling curves. Numerical simulations are shown to be in
close agreement with the analytical predictions.Comment: To appear, PR
Obtaining the spacetime metric from cosmological observations
Recent galaxy redshift surveys have brought in a large amount of accurate
cosmological data out to redshift 0.3, and future surveys are expected to
achieve a high degree of completeness out to a redshift exceeding 1.
Consequently, a numerical programme for determining the metric of the universe
from observational data will soon become practical; and thereby realise the
ultimate application of Einstein's equations. Apart from detailing the cosmic
geometry, this would allow us to verify and quantify homogeneity, rather than
assuming it, as has been necessary up to now, and to do that on a metric level,
and not merely at the mass distribution level. This paper is the beginning of a
project aimed at such a numerical implementation. The primary observational
data from our past light cone consists of galaxy redshifts, apparent
luminosities, angular diameters and number densities, together with source
evolution functions, absolute luminosities, true diameters and masses of
sources. Here we start with the simplest case, that of spherical symmetry and a
dust equation of state, and execute an algorithm that determines the unknown
metric functions from this data. We discuss the challenges of turning the
theoretical algorithm into a workable numerical procedure, particularly
addressing the origin and the maximum in the area distance. Our numerical
method is tested with several artificial data sets for homogeneous and
inhomogeneous models, successfully reproducing the original models. This
demonstrates the basic viability of such a scheme. Although current surveys
don't have sufficient completeness or accuracy, we expect this situation to
change in the near future, and in the meantime there are many refinements and
generalisations to be added.Comment: 26 pages, 10 figures. Minor changes to match the published versio
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