1,573 research outputs found
Dynamic SU(2) Lattice Gauge Theory at Finite Temperature
The dynamic relaxation process for the (2+1)--dimensional SU(2) lattice gauge
theory at critical temperature is investigated with Monte Carlo methods. The
critical initial increase of the Polyakov loop is observed. The dynamic
exponents and as well as the static critical exponent
are determined from the power law behaviour of the Polyakov loop, the
auto-correlation and the second moment at the early stage of the time
evolution. The results are well consistent and universal short-time scaling
behaviour of the dynamic system is confirmed. The values of the exponents show
that the dynamic SU(2) lattice gauge theory is in the same dynamic universality
class as the dynamic Ising model.Comment: 10 pages with 2 figure
Universal Short-time Behaviour of the Dynamic Fully Frustrated XY Model
With Monte Carlo methods we investigate the dynamic relaxation of the fully
frustrated XY model in two dimensions below or at the Kosterlitz-Thouless phase
transition temperature. Special attention is drawn to the sublattice structure
of the dynamic evolution. Short-time scaling behaviour is found and
universality is confirmed. The critical exponent is measured for
different temperature and with different algorithms.Comment: 18 pages, LaTeX, 8 ps-figure
Urban agriculture in the Gauteng City-Region’s green infrastructure network
As cities in developing countries contend with the challenges of urbanisation, they need to rethink the traditional modes of urban planning and development. Part of this logic is the need to cater for growing populations without compromising urban environments or social development. A green infrastructure approach can help meet infrastructure and service needs while ensuring the proper functioning of natural ecological systems. As part of the green infrastructure network, urban agriculture can create multifunctional green assets in the form of urban farms and food gardens. When planned accordingly, urban agriculture can contribute to addressing a range of issues in the Gauteng City-Region (GCR).
The aim of this occasional paper is to gain a better understanding of urban agriculture within the green infrastructure network in the City of Johannesburg and to identify the range of ecosystem services that could be delivered when maintaining and investing in these assets. The analysis in this paper adopts a multi-method approach to (1) identify the interlinkages between urban agriculture and social, economic and environmental systems in the City of Johannesburg; (2) validate these critical interlinkages with stakeholder input and ground-level experience of urban agriculture; and (3) visualise these interlinkages through a spatial analysis of food gardens in the City of Johannesburg.
This paper builds the argument that urban agriculture is a multifunctional element of the green infrastructure network in the GCR. It is worth maintaining and investing in food gardens because they contribute to a number of development imperatives in Gauteng. Food gardens may enhance food security by broadening the range of locally produced food sources that improve the potential to help the poor to access fresh food. Productive food gardens may provide economic opportunities, particularly in areas with minimal access to retail outlets and where unemployment is high. Lastly, as a component of a green infrastructure network, food gardens also help strengthen the provision of a range of key ecosystem services. Inter alia they help address climate change and build disaster resilience through flood management and carbon capture.
Of course, urban agriculture will not deal with any of these challenges in their entirety, but within a wider green infrastructure approach, it has the potential to contribute significantly if it can be mainstreamed into municipal development processes. Realising the benefits of green infrastructure hinges on integrating this approach into municipal planning in a way that aims to improve the productivity of ecosystem service delivery. The paper concludes with recommendations for strengthening policy, management, planning and operational support for food gardens in the GCR
Short-time dynamics and magnetic critical behavior of two-dimensional random-bond Potts model
The critical behavior in the short-time dynamics for the random-bond Potts
ferromagnet in two-dimensions is investigated by short-time dynamic Monte Carlo
simulations. The numerical calculations show that this dynamic approach can be
applied efficiently to study the scaling characteristic, which is used to
estimate the critical exponents theta, beta/nu and z for the quenched disorered
systems from the power-law behavior of the kth moments of magnetizations.Comment: 10 pages, 4 figures Soft Condensed Matte
Analysis of the effect of locally applied inhomogeneous static magnetic field-exposure on mouse ear edema - a double blind study
The effect static magnetic field (SMF)-exposure may exert on edema development has been investigated. A 6 h long whole-body (WBSMF) or local (LSMF), continuous, inhomogeneous SMF-exposure was applied on anesthetized mice in an in vivo model of mustard oil (MO)-induced ear edema. LSMF was applied below the treated ear, below the lumbar spine, or below the mandible. Ear thickness (v) was checked 8 times during the exposure period (at 0, 0.25, 1, 2, 3, 4, 5, and 6 h). The effect size of the applied treatment (eta) on ear thickness was calculated by the formula eta = 100% x (1-vj/vi), where group i is the control group and j is the treated group. Results showed that MO treatment in itself induced a significant ear edema with an effect of 9% (p11% in both cases compared to SMF-exposure alone (p<0.001). In these cases SMF-exposure alone without MO treatment reduced ear thickness significantly (p<0.05), but within estimated experimental error. In cases of LSMF-exposure on the head, a significant SMF-exposure induced ear thickness reduction was found (eta = 5%, p<0.05). LSMF-exposure on the spine affected ear thickness with and without MO treatment almost identically, which provides evidence that the place of local SMF action may be in the lower spinal region
Dynamic Approach to the Fully Frustrated XY Model
Using Monte Carlo simulations, we systematically investigate the
non-equilibrium dynamics of the chiral degree of freedom in the two-dimensional
fully frustrated XY model. The critical initial increase of the staggered
chiral magnetization is observed. By means of the short-time dynamics approach,
we estimate the second order phase transition temperature and all the
dynamic and static critical exponents , z, and .Comment: 5 pages with 6 figures include
Monte Carlo Simulations of Short-time Critical Dynamics with a Conserved Quantity
With Monte Carlo simulations, we investigate short-time critical dynamics of
the three-dimensional anti-ferromagnetic Ising model with a globally conserved
magnetization (not the order parameter). From the power law behavior of
the staggered magnetization (the order parameter), its second moment and the
auto-correlation, we determine all static and dynamic critical exponents as
well as the critical temperature. The universality class of is the same
as that without a conserved quantity, but the universality class of non-zero
is different.Comment: to appear in Phys. Rev.
Universality and scaling study of the critical behavior of the two-dimensional Blume-Capel model in short-time dynamics
In this paper we study the short-time behavior of the Blume-Capel model at
the tricritical point as well as along the second order critical line. Dynamic
and static exponents are estimated by exploring scaling relations for the
magnetization and its moments at early stage of the dynamic evolution. Our
estimates for the dynamic exponents, at the tricritical point, are and .Comment: 12 pages, 9 figure
Abundant Occurrence of Basal Radial Glia in the Subventricular Zone of Embryonic Neocortex of a Lissencephalic Primate, the Common Marmoset Callithrix jacchus
Subventricular zone (SVZ) progenitors are a hallmark of the developing neocortex. Recent studies described a novel type of SVZ progenitor that retains a basal process at mitosis, sustains expression of radial glial markers, and is capable of self-renewal. These progenitors, referred to here as basal radial glia (bRG), occur at high relative abundance in the SVZ of gyrencephalic primates (human) and nonprimates (ferret) but not lissencephalic rodents (mouse). Here, we analyzed the occurrence of bRG cells in the embryonic neocortex of the common marmoset Callithrix jacchus, a near-lissencephalic primate. bRG cells, expressing Pax6, Sox2 (but not Tbr2), glutamate aspartate transporter, and glial fibrillary acidic protein and retaining a basal process at mitosis, occur at similar relative abundance in the marmoset SVZ as in human and ferret. The proportion of progenitors in M-phase was lower in embryonic marmoset than developing ferret neocortex, raising the possibility of a longer cell cycle. Fitting the gyrification indices of 26 anthropoid species to an evolutionary model suggested that the marmoset evolved from a gyrencephalic ancestor. Our results suggest that a high relative abundance of bRG cells may be necessary, but is not sufficient, for gyrencephaly and that the marmoset's lissencephaly evolved secondarily by changing progenitor parameters other than progenitor typ
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