324,785 research outputs found
Using Different Approaches to Evaluate Individual Social Equity in Transport
Inequalities not only exist in the field of economics in relation to income and wealth, but also in other areas, such as the transport sector, where access to and use of different transport modes varies markedly across population groups, and which provides the means to access everyday living activities. A key concern within the transport sector is that inequality has extended beyond the traditional measures of travel, and now covers a wide range of effects relating to social exclusion, freedom, well-being and being able to access reasonable opportunities and resources. In order to address the aforementioned issues, an important question to resolve is what type of methods can be used to measure inequalities in transport most effectively. Therefore, this study aims to apply different approaches, including the Capabilities Approach (CA) and a further six inequality indices, namely the Gini coefficient, the Atkinson index, the Palma ratio, the Pietra ratio, the Schutz coefficient and the Theil index, to the case study using the relatively migrant-rich lower-income neighbourhood of Tuqiao, in Beijing, in order to assess individual transport-related social inequity issues. The findings suggest that the CA is useful in assessing transport-related inequalities where there are significant barriers to the take up of accessibility, for example where there are high levels of disadvantaged groups and disaggregated analysis can be undertaken. The Palma ratio appears to have a larger effect than the Gini coefficient and the other inequality indices when measuring transport-related social inequity. In addition, we also found that most income inequality methods adapted from econometrics may be better suited to measuring transport-related social inequity between different regions, cities or countries, or within the same area, but at different points in time, rather than to measuring a single neighbourhood as a whole. Finally, we argue that to what extent politicians or transport planners can use appropriate management tools to measure transport-related social inequalities may be significant in terms of the progress that can be made in the fight against social inequity in the transport field
A covariant entropy bound conjecture on the dynamical horizon
As a compelling pattern for the holographic principle, our covariant entropy
bound conjecture is proposed for more general dynamical horizons. Then we apply
our conjecture to CDM cosmological models, where we find it imposes a
novel upper bound on the cosmological constant for our own universe
by taking into account the dominant entropy contribution from super-massive
black holes, which thus provides an alternative macroscopic perspective to
understand the longstanding cosmological constant problem. As an intriguing
implication of this conjecture, we also discuss the possible profound relation
between the present cosmological constant, the origin of mass, and the
anthropic principle.Comment: JHEP style, 9 pages, 1 figure, honorable mention award received from
Gravity Research Foundation for 2008 Essay Competitio
Note on the thermal history of decoupled massive particles
This note provides an alternative approach to the momentum decay and thermal
evolution of decoupled massive particles. Although the ingredients in our
results have been addressed in Ref.\cite{Weinberg}, the strategies employed
here are simpler, and the results obtained here are more general.Comment: JHEP style, 4 pages, to appear in CQ
The Picard group of the loop space of the Riemann sphere
The loop space of the Riemann sphere consisting of all C^k or Sobolev W^{k,p}
maps from the circle S^1 to the sphere is an infinite dimensional complex
manifold. We compute the Picard group of holomorphic line bundles on this loop
space as an infinite dimensional complex Lie group with Lie algebra the first
Dolbeault group. The group of Mobius transformations G and its loop group LG
act on this loop space. We prove that an element of the Picard group is
LG-fixed if it is G-fixed; thus completely answer the question by Millson and
Zombro about G-equivariant projective embedding of the loop space of the
Riemann sphere.Comment: International Journal of Mathematic
Oscillation-free method for semilinear diffusion equations under noisy initial conditions
Noise in initial conditions from measurement errors can create unwanted
oscillations which propagate in numerical solutions. We present a technique of
prohibiting such oscillation errors when solving initial-boundary-value
problems of semilinear diffusion equations. Symmetric Strang splitting is
applied to the equation for solving the linear diffusion and nonlinear
remainder separately. An oscillation-free scheme is developed for overcoming
any oscillatory behavior when numerically solving the linear diffusion portion.
To demonstrate the ills of stable oscillations, we compare our method using a
weighted implicit Euler scheme to the Crank-Nicolson method. The
oscillation-free feature and stability of our method are analyzed through a
local linearization. The accuracy of our oscillation-free method is proved and
its usefulness is further verified through solving a Fisher-type equation where
oscillation-free solutions are successfully produced in spite of random errors
in the initial conditions.Comment: 19 pages, 9 figure
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