17,690 research outputs found
Decomposing changes in income risk using consumption data
This paper concerns the decomposition of income risk into permanent and transitory components using repeated cross-section data on income and consumption. Our focus is on the detection of changes in the magnitudes of variances of permanent and transitory risks. A new approximation to the optimal consumption growth rule is developed.
Evidence from a dynamic stochastic simulation is used to show that this approximation can provide a robust method for decomposing income risk in a nonstationary environment. We examine robustness to unobserved heterogeneity in consumption growth and to unobserved heterogeneity in income growth. We use this approach to investigate the growth in income inequality in the UK in the 1980s
Virtual copies of semisimple Lie algebras in enveloping algebras of semidirect products and Casimir operators
Given a semidirect product of semisimple
Lie algebras and solvable algebras , we construct
polynomial operators in the enveloping algebra of
that commute with and transform like the generators of
, up to a functional factor that turns out to be a Casimir operator
of . Such operators are said to generate a virtual copy of
in , and allow to compute the Casimir operators of
in closed form, using the classical formulae for the invariants of
. The behavior of virtual copies with respect to contractions of Lie
algebras is analyzed. Applications to the class of Hamilton algebras and their
inhomogeneous extensions are given.Comment: 20 pages, 2 Appendice
Income risk and consumption inequality: a simulation study
This paper assesses the accuracy of decomposing income risk into permanent and transitory components using income and consumption data. We develop a specific approximation to the optimal consumption growth rule and use Monte Carlo evidence to show that this approximation can provide a robust method for decomposing income risk. The availability of asset data enables the use of a more accurate approximation allowing for partial self-insurance against permanent shocks. We show that the use of data on median asset holdings corrects much of the error in the simple approximation which assumes no self-insurance against permanent shocks
The Red Queen visits Minkowski Space
When Alice went `Through the Looking Glass' [1], she found herself in a
situation where she had to run as fast as she could in order to stay still. In
accordance with the dictum that truth is stranger than fiction, we will see
that it is possible to find a situation in special relativity where running
towards one's target is actually counter-productive. Although the situation is
easily analysed algebraically, the qualitative properties of the analysis are
greatly illuminated by the use of space-time diagrams
Electrostatic propulsion system with a direct nuclear electrogenerator Patent
Nuclear electric generator for accelerating charged propellant particles in electrostatic propulsion syste
Reciprocal relativity of noninertial frames: quantum mechanics
Noninertial transformations on time-position-momentum-energy space {t,q,p,e}
with invariant Born-Green metric ds^2=-dt^2+dq^2/c^2+(1/b^2)(dp^2-de^2/c^2) and
the symplectic metric -de/\dt+dp/\dq are studied. This U(1,3) group of
transformations contains the Lorentz group as the inertial special case. In the
limit of small forces and velocities, it reduces to the expected Hamilton
transformations leaving invariant the symplectic metric and the nonrelativistic
line element ds^2=dt^2. The U(1,3) transformations bound relative velocities by
c and relative forces by b. Spacetime is no longer an invariant subspace but is
relative to noninertial observer frames. Born was lead to the metric by a
concept of reciprocity between position and momentum degrees of freedom and for
this reason we call this reciprocal relativity.
For large b, such effects will almost certainly only manifest in a quantum
regime. Wigner showed that special relativistic quantum mechanics follows from
the projective representations of the inhomogeneous Lorentz group. Projective
representations of a Lie group are equivalent to the unitary reprentations of
its central extension. The same method of projective representations of the
inhomogeneous U(1,3) group is used to define the quantum theory in the
noninertial case. The central extension of the inhomogeneous U(1,3) group is
the cover of the quaplectic group Q(1,3)=U(1,3)*s H(4). H(4) is the
Weyl-Heisenberg group. A set of second order wave equations results from the
representations of the Casimir operators
The “Demand Side” of Transnational Bribery and Corruption: Why Leveling the Playing Field on the Supply Side Isn’t Enough
The domestic and international legal framework for combating bribery and corruption (“ABC laws”), including both private and public corrupt practices that are transnational (cross border) in character, has dramatically expanded over the last twenty years. Despite these developments, major gaps remain. This Article examines one of the largest systemic gaps: the absence of effective tools to control the demand side of transnational bribery and corruption—the corrupt solicitation of a benefit—especially when it involves a public official
Neutrino masses in quartification schemes
The idea of quark-lepton universality at high energies has recently been
explored in unified theories based upon the quartification gauge group SU(3)^4.
These schemes encompass a quark-lepton exchange symmetry that results upon the
introduction of leptonic colour. It has been demonstrated that in models in
which the quartification gauge symmetry is broken down to the standard model
gauge group, gauge coupling constant unification can be achieved, and there is
no unique scenario. The same is also true when the leptonic colour gauge group
is only partially broken, leaving a remnant SU(2)_\ell symmetry at the standard
model level. Here we perform an analysis of the neutrino mass spectrum of such
models. We show that these models do not naturally generate small Majorana
neutrino masses, thus correcting an error in our earlier quartification paper,
but with the addition of one singlet neutral fermion per family there is a
realisation of see-saw suppressed masses for the neutrinos. We also show that
these schemes are consistent with proton decay.Comment: 12 pages, minor changes. To appear in Phys. Rev.
Projective Representations of the Inhomogeneous Hamilton Group: Noninertial Symmetry in Quantum Mechanics
Symmetries in quantum mechanics are realized by the projective
representations of the Lie group as physical states are defined only up to a
phase. A cornerstone theorem shows that these representations are equivalent to
the unitary representations of the central extension of the group. The
formulation of the inertial states of special relativistic quantum mechanics as
the projective representations of the inhomogeneous Lorentz group, and its
nonrelativistic limit in terms of the Galilei group, are fundamental examples.
Interestingly, neither of these symmetries includes the Weyl-Heisenberg group;
the hermitian representations of its algebra are the Heisenberg commutation
relations that are a foundation of quantum mechanics. The Weyl-Heisenberg group
is a one dimensional central extension of the abelian group and its unitary
representations are therefore a particular projective representation of the
abelian group of translations on phase space. A theorem involving the
automorphism group shows that the maximal symmetry that leaves invariant the
Heisenberg commutation relations are essentially projective representations of
the inhomogeneous symplectic group. In the nonrelativistic domain, we must also
have invariance of Newtonian time. This reduces the symmetry group to the
inhomogeneous Hamilton group that is a local noninertial symmetry of Hamilton's
equations. The projective representations of these groups are calculated using
the Mackey theorems for the general case of a nonabelian normal subgroup
Processing peracetic acid treated bloodmeal into bioplastic
Renewable and biodegradable bioplastics can be produced from biopolymers such as proteins. Animal blood is a by-product from meat processing and is rich in protein. It is dried into low value bloodmeal and is used as animal feed or fertiliser. Previous work has shown that bloodmeal can be converted into a thermoplastic using water, urea, sodium dodecyl sulphate (SDS), sodium sulphite and triethylene glycol (TEG). To increase its range of applications and acceptance from consumers, the colour and odour was removed from bloodmeal using peracetic acid (PAA). The aim of this study was to investigate the bioplastic processing of 3-5% (w/w) PAA treated bloodmeal.
3-5% PAA treated bloodmeal powder was compression moulded using different combinations of water, TEG, glycerol, SDS, sodium sulphite, urea, borax, salt and sodium silicate at concentrations up to 60 parts per hundred bloodmeal (pphBM). Partially consolidated extrudates and fully consolidated compression moulded sheets were obtained using a combination of water, TEG and SDS. 4% PAA treated bloodmeal produced the best compression moulded sheets and extrudates and was chosen for investigating the effects of water, TEG and SDS concentration on consolidation, specific mechanical energy input (SME) and product colour during extrusion.
Analysis of variance (ANOVA) showed SDS was the most important factor influencing its ability to be extruded because it detangled protein chains and allowed them to form new stabilising interactions required for consolidation. The best extruded sample, which was 98% consolidated and 49% white, contained 40 pphBM water, 10 pphBM TEG and 6 pphBM SDS
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