4,780 research outputs found
The right to spatial development for human flourishing
This paper explores the literature on spatial development for peopleâs multifaceted well-being and the rights to the city, and argues for peopleâs right to live with dignity in cities. Nature and people-friendly spatial developments are fundamental to nourishing capabilities of human beings and realising their well-being. However, in reality, spatial developments are determined by legal planning and development regimes and socio-cultural discourses. These allocate different âclaims, privileges and power rightsâ to different stakeholders, and the results may not contribute to human flourishing. This paper attempts to synthesise an evaluation framework to achieve flourishing life with dignity in cities
Causal Bulk Viscous Dissipative Isotropic Cosmologies with Variable Gravitational and Cosmological Constants
We consider the evolution of a flat Friedmann-Robertson-Walker Universe,
filled with a causal bulk viscous cosmological fluid, in the presence of
variable gravitational and cosmological constants. The basic equation for the
Hubble parameter, generalizing the evolution equation in the case of constant
gravitational coupling and cosmological term, is derived, under the
supplementary assumption that the total energy of the Universe is conserved. By
assuming that the cosmological constant is proportional to the square of the
Hubble parameter and a power law dependence of the bulk viscosity coefficient,
temperature and relaxation time on the energy density of the cosmological
fluid, two classes of exact solutions of the field equations are obtained. In
the first class of solutions the Universe ends in an inflationary era, while in
the second class of solutions the expansion of the Universe is non-inflationary
for all times. In both models the cosmological "constant" is a decreasing
function of time, while the gravitational "constant" increases in the early
period of evolution of the Universe, tending in the large time limit to a
constant value.Comment: 14 pages, 15 figure
Modeling usual and unusual anisotropic spheres
In this paper, we study anisotropic spheres built from known static spherical
solutions. In particular, we are interested in the physical consequences of a
"small" departure from a physically sensible configuration. The obtained
solutions smoothly depend on free parameters. By setting these parameters to
zero, the starting seed solution is regained. We apply our procedure in detail
by taking as seed solutions the Florides metrics, and the Tolman IV solution.
We show that the chosen Tolman IV, and also Heint IIa Durg IV,V perfect fluid
solutions, can be used to generate a class of parametric solutions where the
anisotropic factor has features recalling boson stars. This is an indication
that boson stars could emerge by "perturbing" appropriately a perfect fluid
solution (at least for the seed metrics considered). Finally, starting with
Tolman IV, Heint IIa and Durg IV,V solutions, we build anisotropic
gravastar-like sources with the appropriate boundary conditions.Comment: Final version published in IJMP
A Unified Strategy to ent-Kauranoid Natural Products: Total Syntheses of (â)-Trichorabdal A and (â)-Longikaurin E
The first total syntheses of (â)-trichorabdal A and (â)-longikaurin E are reported. A unified synthetic strategy is employed that relies on a Pd-mediated oxidative cyclization of a silyl ketene acetal to generate an all-carbon quaternary center and build the bicyclo[3.2.1]octane framework. These studies, taken together with our previous synthesis of (â)-maoecrystal Z, demonstrate that three architecturally distinct ent-kauranoids can be prepared from a common spirolactone intermediate
Anisotropic static solutions in modelling highly compact bodies
Einstein field equations for anisotropic spheres are solved and exact
interior solutions obtained. This paper extends earlier treatments to include
anisotropic models which accommodate a wider variety of physically viable
energy densities. Two classes of solutions are possible. The first class
contains the limiting case for the energy density which
arises in many astrophysical applications. In the second class the singularity
at the center of the star is not present in the energy density. The models
presented in this paper allow for increasing and decreasing profiles in the
behavior of the energy density.Comment: 9 pages, to appear in Pramana - J. Phy
Unexpected Neuronal Protection of SU5416 against 1-Methyl-4-Phenylpyridinium Ion-Induced Toxicity via Inhibiting Neuronal Nitric Oxide Synthase
SU5416 was originally designed as a potent and selective inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) for cancer therapy. In this study, we have found for the first time that SU5416 unexpectedly prevented 1-methyl-4-phenylpyridinium ion (MPP +)-induced neuronal apoptosis in cerebellar granule neurons, and decreased 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced loss of dopaminergic neurons and impairment of swimming behavior in zebrafish in a concentration-dependent manner. However, VEGFR-2 kinase inhibitor II, another specific VEGFR-2 inhibitor, failed to reverse neurotoxicity at the concentration exhibiting anti-angiogenic activity, strongly suggesting that the neuroprotective effect of SU5416 is independent from its anti-angiogenic action. SU5416 potently reversed MPP +-increased intracellular nitric oxide level with an efficacy similar to 7-nitroindazole, a specific neuronal nitric oxide synthase (nNOS) inhibitor. Western blotting analysis showed that SU5416 reduced the elevation of nNOS protein expression induced by MPP +. Furthermore, SU5416 directly inhibited the enzyme activity of rat cerebellum nNOS with an IC 50 value of 22.7 ΌM. In addition, knock-down of nNOS expression using short hairpin RNA (shRNA) abolished the neuroprotective effects of SU5416 against MPP +-induced neuronal loss. Our results strongly demonstrate that SU5416 might exert its unexpected neuroprotective effects by concurrently reducing nNOS protein expression and directly inhibiting nNOS enzyme activity. In view of the capability of SU5416 to cross the blood-brain barrier and the safety for human use, our findings further indicate that SU5416 might be a novel drug candidate for neurodegenerative disorders, particularly those associated with NO-mediated neurotoxicity. © 2012 Cui et al.published_or_final_versio
A new algorithm for anisotropic solutions
We establish a new algorithm that generates a new solution to the Einstein
field equations, with an anisotropic matter distribution, from a seed isotropic
solution. The new solution is expressed in terms of integrals of an isotropic
gravitational potential; and the integration can be completed exactly for
particular isotropic seed metrics. A good feature of our approach is that the
anisotropic solutions necessarily have an isotropic limit. We find two examples
of anisotropic solutions which generalise the isothermal sphere and the
Schwarzschild interior sphere. Both examples are expressed in closed form
involving elementary functions only.Comment: 16 pages, to appear in Pramana - J. Phy
Absolute Stability Limit for Relativistic Charged Spheres
We find an exact solution for the stability limit of relativistic charged
spheres for the case of constant gravitational mass density and constant charge
density. We argue that this provides an absolute stability limit for any
relativistic charged sphere in which the gravitational mass density decreases
with radius and the charge density increases with radius. We then provide a
cruder absolute stability limit that applies to any charged sphere with a
spherically symmetric mass and charge distribution. We give numerical results
for all cases. In addition, we discuss the example of a neutral sphere
surrounded by a thin, charged shell.Comment: 25 pages, 1 figure 1 June 07: Replaced with added citations to prior
work along same line
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