1,282 research outputs found
Static as a trope in electronic art: David Hall's 1001 tv sets (end piece) and other works.
Static is often used in electronic art to symbolise a metaphysical outside that is only perceivable with technology. A significant recent example is David Hall's 1001 TV Sets (End Piece). In this paper I will explore the static as outside trope using numerous examples, with a focus on Hall's work. I will show that the trope demonstrates how static can be meaningful and so functions as more than merely interference
Biphasic behaviour in malignant invasion
Invasion is an important facet of malignant growth that enables tumour cells to colonise adjacent regions of normal tissue. Factors known to influence such invasion include the rate at which the tumour cells produce tissue-degrading molecules, or proteases, and the composition of the surrounding tissue matrix. A common feature of experimental studies is the biphasic dependence of the speed at which the tumour cells invade on properties such as protease production rates and the density of the normal tissue. For example, tumour cells may invade dense tissues at the same speed as they invade less dense tissue, with maximal invasion seen for intermediate tissue densities. In this paper, a theoretical model of malignant invasion is developed. The model consists of two coupled partial differential equations describing the behaviour of the tumour cells and the surrounding normal tissue. Numerical methods show that the model exhibits steady travelling wave solutions that are stable and may be smooth or discontinuous. Attention focuses on the more biologically relevant, discontinuous solutions which are characterised by a jump in the tumour cell concentration. The model also reproduces the biphasic dependence of the tumour cell invasion speed on the density of the surrounding normal tissue. We explain how this arises by seeking constant-form travelling wave solutions and applying non-standard phase plane methods to the resulting system of ordinary differential equations. In the phase plane, the system possesses a singular curve. Discontinuous solutions may be constructed by connecting trajectories that pass through particular points on the singular curve and recross it via a shock. For certain parameter values, there are two points at which trajectories may cross the singular curve and, as a result, two distinct discontinuous solutions may arise
Towards a positive youth justice
Purpose - The purpose of this paper is to consider and explore the principles that should inform a positive and progressive approach to conceptualising and delivering youth justice. Design/methodology/approach - Critical literature review, incorporating primary research and evaluation conducted by the authors. Findings - A children first model of positive youth justice should cohere around the promotion of four key principles: children's rights and adults' responsibilities; desistance and inclusion; diversion and systems management; relationship-based partnerships between children and practitioners. Practical implications - The child-friendly, child-appropriate and legitimacy-focused nature of the Children first, offender second (CFOS) model can encourage diversion from formal system contact, can enhance levels of participation and engagement with formal youth justice interventions and promotes positive behaviours and outcomes for children in trouble. Originality/value - The principles outlined progress youth justice into positive forms antithetical to the negative elements of the "new youth justice" and will have relevance to other jurisdictions, rooted as they are in universality, child development and children's rights
A Child Rights-Based Approach to Food Marketing A Guide for Policy Makers
A Child Rights-Based Approach to Food Marketing: A Guide for Policy Makers offers a legal analysis that links
the WHO Recommendations with a human rights framework, particularly the Convention on the Rights
of the Child. In this analysis, the CRC provides the foundation for a child rights-based approach to ending
childhood obesity and the prevention of non-communicable diseases
Using a probabilistic approach to derive a two-phase model of flow-induced cell migration
Interstitial fluid flow is a feature of many solid tumors. In vitro experiments have shown that such fluid flow can direct tumor cell movement upstream or downstream depending on the balance between the competing mechanisms of tensotaxis (cell migration up stress gradients) and autologous chemotaxis (downstream cell movement in response to flow-induced gradients of self-secreted chemoattractants). In this work we develop a probabilistic-continuum, two-phase model for cell migration in response to interstitial flow. We use a kinetic description for the cell velocity probability density function, and model the flow-dependent mechanical and chemical stimuli as forcing terms that bias cell migration upstream and downstream. Using velocity-space averaging, we reformulate the model as a system of continuum equations for the spatiotemporal evolution of the cell volume fraction and flux in response to forcing terms that depend on the local direction and magnitude of the mechanochemical cues. We specialize our model to describe a one-dimensional cell layer subject to fluid flow. Using a combination of numerical simulations and asymptotic analysis, we delineate the parameter regime where transitions from downstream to upstream cell migration occur. As has been observed experimentally, the model predicts downstream-oriented chemotactic migration at low cell volume fractions, and upstream-oriented tensotactic migration at larger volume fractions. We show that the locus of the critical volume fraction, at which the system transitions from downstream to upstream migration, is dominated by the ratio of the rate of chemokine secretion and advection. Our model also predicts that, because the tensotactic stimulus depends strongly on the cell volume fraction, upstream, tensotaxis-dominated migration occurs only transiently when the cells are initially seeded, and transitions to downstream, chemotaxis-dominated migration occur at later times due to the dispersive effect of cell diffusion
Effect of high temperature VPT conditions on the development of aligned ZnO nanorod arrays grown by a three step catalyst-free method
Using Transmission Electron Microscopy-related techniques, we study the effect of the high temperature in the Vapour Phase Transport (VPT) process on the morphology and chemistry of VPT ZnO nanorod arrays deposited on a two-step Chemical Bath Deposition (CBD) buffer layers on silicon substrates. Though well-aligned and c-axis oriented arrays of ZnO nanorods are achieved, we have noticed the strong dependence of the nanorod morphology on the VPT growth conditions such as the temperature ramp rate and the placement of samples with respect to the metal source. The development of conical structures in the nanorod bases and the formation of a double intermediate layer below the base of nanorods are the main features found. The modifications of the ZnO nanostructures both in the base and in the underlying buffer layers due to the high VPT temperatures are also examined in detail
Using a probabilistic approach to derive a two-phase model of flow-induced cell migration
Interstitial fluid flow is a feature of many solid tumours. In vitro
experiments have shown that such fluid flow can direct tumour cell movement
upstream or downstream depending on the balance between the competing
mechanisms of tensotaxis and autologous chemotaxis. In this work we develop a
probabilistic-continuum, two-phase model for cell migration in response to
interstitial flow. We use a Fokker-Planck type equation for the cell-velocity
probability density function, and model the flow-dependent mechanochemical
stimulus as a forcing term which biases cell migration upstream and downstream.
Using velocity-space averaging, we reformulate the model as a system of
continuum equations for the spatio-temporal evolution of the cell volume
fraction and flux, in response to forcing terms which depend on the local
direction and magnitude of the mechanochemical cues. We specialise our model to
describe a one-dimensional cell layer subject to fluid flow. Using a
combination of numerical simulations and asymptotic analysis, we delineate the
parameter regime where transitions from downstream to upstream cell migration
occur. As has been observed experimentally, the model predicts
downstream-oriented, chemotactic migration at low cell volume fractions, and
upstream-oriented, tensotactic migration at larger volume fractions. We show
that the locus of the critical volume fraction, at which the system transitions
from downstream to upstream migration, is dominated by the ratio of the rate of
chemokine secretion and advection. Our model predicts that, because the
tensotactic stimulus depends strongly on the cell volume fraction, upstream
migration occurs only transiently when the cells are initially seeded, and
transitions to downstream migration occur at later times due to the dispersive
effect of cell diffusion.Comment: 20 pages, 6 figures. Submitted to Biophysical Journa
Homogenisation of nonlinear blood flow in periodic networks: the limit of small haematocrit heterogeneity
In this work we develop a homogenisation methodology to upscale mathematical
descriptions of microcirculatory blood flow from the microscale (where
individual vessels are resolved) to the macroscopic (or tissue) scale. Due to
the assumed two-phase nature of blood and specific features of red blood cells
(RBCs), mathematical models for blood flow in the microcirculation are highly
nonlinear, coupling the flow and RBC concentrations (haematocrit). In contrast
to previous works which accomplished blood-flow homogenisation by assuming that
the haematocrit level remains constant, here we allow for spatial heterogeneity
in the haematocrit concentration and thus begin with a nonlinear microscale
model. We simplify the analysis by considering the limit of small haematocrit
heterogeneity which prevails when variations in haematocrit concentration
between neighbouring vessels are small. Homogenisation results in a system of
coupled, nonlinear partial differential equations describing the flow and
haematocrit transport at the macroscale, in which a nonlinear Darcy-type model
relates the flow and pressure gradient via a haematocrit-dependent permeability
tensor. During the analysis we obtain further that haematocrit transport at the
macroscale is governed by a purely advective equation. Applying the theory to
particular examples of two- and three-dimensional geometries of periodic
networks, we calculate the effective permeability tensor associated with blood
flow in these vascular networks. We demonstrate how the statistical
distribution of vessel lengths and diameters, together with the average
haematocrit level, affect the statistical properties of the macroscopic
permeability tensor. These data can be used to simulate blood flow and
haematocrit transport at the macroscale.Comment: 34 pages, 8 figure
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