4,552 research outputs found
Convergence and Contention: The Least Developed Countries in Post-2015 Debates
Of all the development challenges the world has faced over the past 50 years, bringing prosperity to the poorest countries has proven the most stubborn. In 1971 the United Nations established the category of Least Developed Country (LDC) in order to focus special attention and support on its poorest and most vulnerable member states. Since then, only three countries designated as LDCs have moved out of the category, which now includes 48 nations. The UN Millennium Declaration and Millennium Development Goals (MDGs) called for the international community to give priority to LDCs. Although progress has varied greatly, LDCs as a group have lagged far behind the rest of the developing world in achieving the MDGs. LDCs also are especially vulnerable to economic and political shocks and environmental threats such as climate change, which compound the challenges they face.LDCs can offer important lessons on past development failures and successes, and testing grounds for new approaches. As the international community develops a new global development framework to replace the MDGs when they expire in 2015, it would do well to listen to what LDC development experts and observers are saying. In many ways, the success of this new post-2015 agenda may be judged by how effectively it contributes to development progress in this group of countries. As an input to post-2015 debates, this paper scans a wide range of perspectives on how the post-2015 agenda can most effectively support the LDCs' development priorities. It identifies many areas of agreement on the challenges that LDCs face. It also finds a number of areas of disagreement, particularly on the strategies and measures needed for LDCs to achieve sustainable, equitable social and economic progress
Experience with the CAIS
Intermetrics' experience is that the Ada package construct, which allows separation of specification and implementation allows specification of a CAIS that is transportable across varying hardware and software bases. Additionally, the CAIS is an excellent basis for providing operating system functionality to Ada applications. By allowing the Byron APSE to be moved easily from system to system, and allowing significant re-writes of underlying code. Ada and the CAIS provide portability as well as transparency to change at the application operating system interface level
Normal stresses, contraction, and stiffening in sheared elastic networks
When elastic solids are sheared, a nonlinear effect named after Poynting
gives rise to normal stresses or changes in volume. We provide a novel relation
between the Poynting effect and the microscopic Gr\"uneisen parameter, which
quantifies how stretching shifts vibrational modes. By applying this relation
to random spring networks, a minimal model for, e.g., biopolymer gels and solid
foams, we find that networks contract or develop tension because they vibrate
faster when stretched. The amplitude of the Poynting effect is sensitive to the
network's linear elastic moduli, which can be tuned via its preparation
protocol and connectivity. Finally, we show that the Poynting effect can be
used to predict the finite strain scale where the material stiffens under
shear.Comment: 5 pages, 5 figure
Convergence of derivative expansions of the renormalization group
We investigate the convergence of the derivative expansion of the exact
renormalization group, by using it to compute the beta function of scalar field
theory. We show that the derivative expansion of the Polchinski flow equation
converges at one loop for certain fast falling smooth cutoffs. The derivative
expansion of the Legendre flow equation trivially converges at one loop, but
also at two loops: slowly with sharp cutoff (as a momentum-scale expansion),
and rapidly in the case of a smooth exponential cutoff. Finally, we show that
the two loop contributions to certain higher derivative operators (not involved
in beta) have divergent momentum-scale expansions for sharp cutoff, but the
smooth exponential cutoff gives convergent derivative expansions for all such
operators with any number of derivatives.Comment: Latex inc axodraw. 20 page
Derivative Expansions of the Exact Renormalisation Group and SU(N|N) Gauge Theory
We investigate the convergence of the derivative expansion of the exact
renormalisation group, by using it to compute the beta function of scalar
theory. We demonstrate that the derivative expansion of the Polchinski flow
equation converges at one loop for certain fast falling smooth cutoffs. The
derivative expansion of the Legendre flow equation trivially converges at one
loop, but also at two loops: slowly with sharp cutoff (as a momentum-scale
expansion), and rapidly in the case of a smooth exponential cutoff. We also
show that the two loop contributions to certain higher derivative operators
(not involved in beta) have divergent momentum-scale expansions for sharp
cutoff, but the smooth exponential cutoff gives convergent derivative
expansions for all such operators with any number of derivatives. In the latter
part of the thesis, we address the problems of applying the exact
renormalisation group to gauge theories. A regularisation scheme utilising
higher covariant derivatives and the spontaneous symmetry breaking of the gauge
supergroup SU(N|N) is introduced and it is demonstrated to be finite to all
orders of perturbation theory.Comment: Thesis,LaTex,128 pages,14 eps figure
Force balance in canonical ensembles of static granular packings
We investigate the role of local force balance in the transition from a
microcanonical ensemble of static granular packings, characterized by an
invariant stress, to a canonical ensemble. Packings in two dimensions admit a
reciprocal tiling, and a collective effect of force balance is that the area of
this tiling is also invariant in a microcanonical ensemble. We present
analytical relations between stress, tiling area and tiling area fluctuations,
and show that a canonical ensemble can be characterized by an intensive
thermodynamic parameter conjugate to one or the other. We test the equivalence
of different ensembles through the first canonical simulations of the force
network ensemble, a model system.Comment: 9 pages, 9 figures, submitted to JSTA
Quantum energy flow, dissipation and decoherence in mesoscopic dielectric structures
We first present a summary of recent results concerning the phononic energy
transport properties of mesoscopic, suspended dielectric wires. We then discuss
some related open problems concerning the fundamental lower limits on the
vibrational damping rates of submicron-sized cantilever structures and also the
possibility to create and detect quantum superpositions of spatially separated
states for such structures.Comment: To appear in Physica B, Proceedings of the 9th International
Conference on Phonon Scattering (Phonons 98
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