961 research outputs found
Directed Percolation and Generalized Friendly Walkers
We show that the problem of directed percolation on an arbitrary lattice is
equivalent to the problem of m directed random walkers with rather general
attractive interactions, when suitably continued to m=0. In 1+1 dimensions,
this is dual to a model of interacting steps on a vicinal surface. A similar
correspondence with interacting self-avoiding walks is constructed for
isotropic percolation.Comment: 4 pages, 3 figures, to be published in Phys. Rev. Let
The influence of breed and plane of nutrition on the chronology of the teeth eruption in sheep
No Abstrac
Mapping spatial tourism and hospitality employment clusters: An application of spatial autocorrelation
This article analyzes the characteristics and spatial clustering of tourism and hospitality employment clusters in Victoria, Australia. Using cluster theory as the theoretical base, three interrelated research questions are specifically addressed: What industries constitute the tourism and hospitality sector? What broader "groupings" does the sector exhibit? Are these tourism and hospitality industries clustered around strategic areas of economic and resource advantage? Using the Australian and New Zealand Standard Industrial Classification (at the four-digit level), industries explicitly related to tourism and hospitality were first identified and total numbers of individuals working within these industries were aggregated at a level of Statistical Local Area (similar to a suburb or a neighborhood). Results show that in 2006 employment in tourism and hospitality equate to 7.74% of total employment in Australia. "Cafés and restaurants" (22%) is the single largest tourism and hospitality-related employer, followed by "takeaway food services" (20%) and "accommodation" (16%). Using factor analysis, four broader functions were extracted to characterize the underlying structure and functional interdependency among tourism and hospitality industries. These functions include: tourism operational services, hospitality services, entertainment services, and infrastructure operational facilities services. Spatial autocorrelation measures have identified five established tourism and hospitality spatial clusters in Victoria, which we argue hold the potential to act as tourism growth foci to create business synergy and generate spill-over effects through regional collaboration, competition, and sharing of pooled resources between firm
Evaluation of Novel Imidazotetrazine Analogues Designed to Overcome Temozolomide Resistance and Glioblastoma Regrowth
The cellular responses to two new temozolomide (TMZ) analogues, DP68 and DP86, acting against glioblastoma multi- forme (GBM) cell lines and primary culture models are reported. Dose–response analysis of cultured GBM cells revealed that DP68 is more potent than DP86 and TMZ and that DP68 was effective even in cell lines resistant to TMZ. On the basis of a serial neurosphere assay, DP68 inhibits repop- ulation of these cultures at low concentrations. The efficacy of these compounds was independent of MGMT and MMR func- tions. DP68-induced interstrand DNA cross-links were dem- onstrated with H2O2-treated cells. Furthermore, DP68 induced a distinct cell–cycle arrest with accumulation of cells in S phase that is not observed for TMZ. Consistent with this biologic response, DP68 induces a strong DNA damage response, including phosphorylation of ATM, Chk1 and Chk2 kinases, KAP1, and histone variant H2AX. Suppression of FANCD2 expression or ATR expression/kinase activity enhanced anti- glioblastoma effects of DP68. Initial pharmacokinetic analysis revealed rapid elimination of these drugs from serum. Collec- tively, these data demonstrate that DP68 is a novel and potent antiglioblastoma compound that circumvents TMZ resistance, likely as a result of its independence from MGMT and mismatch repair and its capacity to cross-link strands of DN
Switching dynamics of surface stabilized ferroelectric liquid crystal cells: effects of anchoring energy asymmetry
We study both theoretically and experimentally switching dynamics in surface
stabilized ferroelectric liquid crystal cells with asymmetric boundary
conditions. In these cells the bounding surfaces are treated differently to
produce asymmetry in their anchoring properties. Our electro-optic measurements
of the switching voltage thresholds that are determined by the peaks of the
reversal polarization current reveal the frequency dependent shift of the
hysteresis loop. We examine the predictions of the uniform dynamical model with
the anchoring energy taken into account. It is found that the asymmetry effects
are dominated by the polar contribution to the anchoring energy. Frequency
dependence of the voltage thresholds is studied by analyzing the properties of
time-periodic solutions to the dynamical equation (cycles). For this purpose,
we apply the method that uses the parameterized half-period mappings for the
approximate model and relate the cycles to the fixed points of the composition
of two half-period mappings. The cycles are found to be unstable and can only
be formed when the driving frequency is lower than its critical value. The
polar anchoring parameter is estimated by making a comparison between the
results of modelling and the experimental data for the shift vs frequency
curve. For a double-well potential considered as a deformation of the
Rapini-Papoular potential, the branch of stable cycles emerges in the low
frequency region separated by the gap from the high frequency interval for
unstable cycles.Comment: 35 pages, 15 figure
ASYMPTOTIC BEHAVIOR OF COMPLEX SCALAR FIELDS IN A FRIEDMAN-LEMAITRE UNIVERSE
We study the coupled Einstein-Klein-Gordon equations for a complex scalar
field with and without a quartic self-interaction in a curvatureless
Friedman-Lema\^{\i}\-tre Universe. The equations can be written as a set of
four coupled first order non-linear differential equations, for which we
establish the phase portrait for the time evolution of the scalar field. To
that purpose we find the singular points of the differential equations lying in
the finite region and at infinity of the phase space and study the
corresponding asymptotic behavior of the solutions. This knowledge is of
relevance, since it provides the initial conditions which are needed to solve
numerically the differential equations. For some singular points lying at
infinity we recover the expected emergence of an inflationary stage.Comment: uuencoded, compressed tarfile containing a 15 pages Latex file and 2
postscipt figures. Accepted for publication on Phys. Rev.
Modelling the spatial pattern of housing-renovation employment in Melbourne, Australia: an application of geographically weighted regression
This paper discusses research aimed at identifying key factors influencing the distribution of residential housing renovation employment in metropolitan Melbourne. Using Geographically Weighted Regression (GWR), employment focused on residential housing renovation is modelled using six parameters representing urban space: distance to the central business district, median household income, distance to highways, the number of nearby shopping centres, distance to public open space and accessibility to railway stations. Of the six different explanatory variables, the estimated value of the Ordinary Least Square model for distance to CBD and open space were statistically significant. Mapping the values of local coefficient estimates of independent variables revealed their extent of influence and variation in residential housing renovation employment
Devil's Staircase in Magnetoresistance of a Periodic Array of Scatterers
The nonlinear response to an external electric field is studied for classical
non-interacting charged particles under the influence of a uniform magnetic
field, a periodic potential, and an effective friction force. We find numerical
and analytical evidence that the ratio of transversal to longitudinal
resistance forms a Devil's staircase. The staircase is attributed to the
dynamical phenomenon of mode-locking.Comment: two-column 4 pages, 5 figure
Scaling limit of vicious walks and two-matrix model
We consider the diffusion scaling limit of the one-dimensional vicious walker
model of Fisher and derive a system of nonintersecting Brownian motions. The
spatial distribution of particles is studied and it is described by use of
the probability density function of eigenvalues of Gaussian random
matrices. The particle distribution depends on the ratio of the observation
time and the time interval in which the nonintersecting condition is
imposed. As is going on from 0 to 1, there occurs a transition of
distribution, which is identified with the transition observed in the
two-matrix model of Pandey and Mehta. Despite of the absence of matrix
structure in the original vicious walker model, in the diffusion scaling limit,
accumulation of contact repulsive interactions realizes the correlated
distribution of eigenvalues in the multimatrix model as the particle
distribution.Comment: REVTeX4, 12 pages, no figure, minor corrections made for publicatio
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