Scaling properties of the cluster distribution of a critical nonequilibrium model

A geometric approach to critical fluctuations of a nonequilibrium model is reported. The two-dimensional majority vote model was investigated by Monte Carlo simulations on square lattices of various sizes and a detailed scaling analysis of cluster statistical and geometric properties was performed. The cluster distribution exponents and fractal dimension were found to be the same as those of the (two-dimensional) Ising model. This result, which cannot be derived purely from the known bulk critical behaviour, widens our knowledge about the range of validity of the Ising universality class for nonequilibrium systems.Comment: to appear in Physica

Non-isothermal nucleation in strongly supercooled liquids

In a strongly supercooled liquid at a temperature below the unit supercooling, a solid nucleus may grow such that the latent heat of freezing stays essentially within the nucleus. The temperature in the nucleus is then higher than in the surrounding liquid. We investigate the possibility that nucleation there may occur nonisothermally. We conclude that this is generally not the case

Electrically Enhanced Free Dendrite Growth in Polar and Non-polar Systems

We describe the electrically enhanced growth of needle crystals from the vapor phase, for which there exists a morphological instability above a threshold applied potential. Our improved theoretical treatment of this phenomenon shows that the instability is present in both polar and non-polar systems, and we provide an extension of solvability theory to include electrical effects. We present extensive experimental data for ice needle growth above the electrical threshold, where at $T=-5$C high-velocity shape-preserving growth is observed. These data indicate that the needle tip assumes an effective radius} $R^{\ast}$ which is nearly independent of both supersaturation and the applied potential. The small scale of $R^{\ast}$ and its response to chemical additives suggest that the needle growth rate is being limited primarily by structural instabilities, possibly related to surface melting. We also demonstrate experimentally that non-polar systems exhibit this same electrically induced morphological instability

Monte Carlo Simulation of a Random-Field Ising Antiferromagnet

Phase transitions in the three-dimensional diluted Ising antiferromagnet in an applied magnetic field are analyzed numerically. It is found that random magnetic field in a system with spin concentration below a certain threshold induces a crossover from second-order phase transition to first-order transition to a new phase characterized by a spin-glass ground state and metastable energy states at finite temperatures.Comment: 10 pages, 11 figure

Immune-mediated mechanisms influencing the efficacy of anticancer therapies

Conventional anticancer therapies, such as chemotherapy, radiotherapy, and targeted therapy, are designed to kill cancer cells. However, the efficacy of anticancer therapies is not only determined by their direct effects on cancer cells but also by off-target effects within the host immune system. Cytotoxic treatment regimens elicit several changes in immune-related parameters including the composition, phenotype, and function of immune cells. Here we discuss the impact of innate and adaptive immune cells on the success of anticancer therapy. In this context we examine the opportunities to exploit host immune responses to boost tumor clearing, and highlight the challenges facing the treatment of advanced metastatic disease

Some Consequences of Thermosolutal Convection: The Grain Structure of Castings

The essential principles of thermosolutal convection are outlined, and how convection provides a transport mechanism between the mushy region of a casting and the open bulk liquid is illustrated. The convective flow patterns which develop assist in heat exchange and macroscopic solute segregation during solidification; they also provide a mechanism for the transport of dendritic fragments from the mushy region into the bulk liquid. Surviving fragments become nuclei for equiaxed grains and so lead to blocking of the parental columnar, dendritic growth front from which they originated. The physical steps in such a sequence are considered and some experimental data are provided to support the argument