Scaling regimes and critical dimensions in the Kardar-Parisi-Zhang problem

We study the scaling regimes for the Kardar-Parisi-Zhang equation with noise correlator R(q) ~ (1 + w q^{-2 \rho}) in Fourier space, as a function of \rho and the spatial dimension d. By means of a stochastic Cole-Hopf transformation, the critical and correction-to-scaling exponents at the roughening transition are determined to all orders in a (d - d_c) expansion. We also argue that there is a intriguing possibility that the rough phases above and below the lower critical dimension d_c = 2 (1 + \rho) are genuinely different which could lead to a re-interpretation of results in the literature.Comment: Latex, 7 pages, eps files for two figures as well as Europhys. Lett. style files included; slightly expanded reincarnatio

Heat transfer to two-phase air/water mixtures flowing in small tubes with inlet disequilibrium

The cooling of gas turbine components was the subject of considerable research. The problem is difficult because the available coolant, compressor bleed air, is itself quite hot and has relatively poor thermophysical properties for a coolant. Injecting liquid water to evaporatively cool the air prior to its contact with the hot components was proposed and studied, particularly as a method of cooling for contingency power applications. Injection of a small quantity of cold liquid water into a relatively hot coolant air stream such that evaporation of the liquid is still in process when the coolant contacts the hot component was studied. No approach was found whereby heat transfer characteristics could be confidently predicted for such a case based solely on prior studies. It was not clear whether disequilibrium between phases at the inlet to the hot component section would improve cooling relative to that obtained where equilibrium was established prior to contact with the hot surface

Exploring prospects of novel drugs for tuberculosis

Tuberculosis remains a disease with an enormous impact on public health worldwide. With the continuously increasing epidemic of drug-resistant tuberculosis, new drugs are desperately needed. However, even for the treatment of drug-sensitive tuberculosis, new drugs are required to shorten the treatment duration and thereby prevent development of drug resistance. Within the past ten years, major advances in tuberculosis drug research have been made, leading to a considerable number of antimycobacterial compounds which are now in the pipeline. Here we discuss a number of these novel promising tuberculosis drugs, as well as the discovery of two new potential drug targets for the development of novel effective drugs to curb the tuberculosis pandemic, ie, the coronin 1 and protein kinase G pathways. Protein kinase G is secreted by mycobacteria and is responsible for blocking lysosomal delivery within the macrophage. Coronin 1 is responsible for activating the phosphatase, calcineurin, and thereby preventing phagosome-lysosome fusion within the macrophage. Blocking these two pathways may lead to rapid killing of mycobacteri

Drived diffusion of vector fields

A model for the diffusion of vector fields driven by external forces is proposed. Using the renormalization group and the $\epsilon$-expansion, the dynamical critical properties of the model with gaussian noise for dimensions below the critical dimension are investigated and new transport universality classes are obtained.Comment: 11 pages, title changed, anisotropic diffusion further discussed and emphasize

Pulmonary giant cells and their significance for the diagnosis of asphyxiation

This study was performed to prove whether the detection of polynuclear giant cells in lungs is useful for the diagnosis of asphyxiation due to throttling or strangulation. Therefore, lung specimens of 54 individuals with different natural and unnatural causes of death were investigated. In most lungs examined numerous alveolar macrophages with 1-2 nuclei were found. Polynuclear giant cells, which were arbitrarily defined as alveolar macrophages containing 3 or more nuclei, were observed in all groups investigated except in the cases of hypoxia due to covering the head with plastic bags. Apparent differences between the other groups in particular an increased number in cases of throttling or strangulation, could not be observed. Immunohistochemical investigations confirmed the hypothesis that the observed polynuclear giant cells were derived from alveolar macrophages. The immunohistochemical analysis of the proliferation marker antigen Ki 67 revealed no positive reaction in the nuclei of polynuclear giant cells indicating that these cells had not developed shortly before death by endomitosis as an adaptative change following reduction in oxygen supply. The results provide evidence that the detection of pulmonary polynuclear giant cells cannot be used as a practical indicator for death by asphyxiation due to throttling or strangulation

Laserlight visual cueing device for freezing of gait in Parkinson's disease: a case study of the biomechanics involved

AbstractBackground: Freezing of gait (FOG) is a serious gait disorder affecting up to two-thirds of people with Parkinson's disease (PD). Cueing has been explored as a method of generating motor execution using visual transverse lines on the floor. However, the impact of a laser light visual cue remains unclear. Objective: To determine the biomechanical effect of a laser cane on FOG in a participant with PD compared to a healthy age- and gender-matched control. Methods: The participant with PD and healthy control were given a task of initiating gait from standing. Electromyography (EMG) data were collected from the tibialis anterior (TA) and the medial gastrocnemius (GS) muscles using an 8-channel system. A 10-camera system (Qualisys) recorded movement in 6 degrees of freedom and a calibrated anatomical system technique was used to construct a full body model. Center of mass (COM) and center of pressure (COP) were the main outcome measures. Results: The uncued condition showed that separation of COM and COP took longer and was of smaller magnitude than the cued condition. EMG activity revealed prolonged activation of GS, with little to no TA activity. The cued condition showed earlier COM and COP separation. There was reduced fluctuation in GS, with abnormal, early bursts of TA activity. Step length improved in the cued condition compared to the uncued condition. Conclusion: Laserlight visual cueing improved step length beyond a non-cued condition for this patient indicating improved posture and muscle control

Spontaneous Symmetry Breaking in Directed Percolation with Many Colors: Differentiation of Species in the Gribov Process

A general field theoretic model of directed percolation with many colors that is equivalent to a population model (Gribov process) with many species near their extinction thresholds is presented. It is shown that the multicritical behavior is always described by the well known exponents of Reggeon field theory. In addition this universal model shows an instability that leads in general to a total asymmetry between each pair of species of a cooperative society.Comment: 4 pages, 2 Postscript figures, uses multicol.sty, submitte

Optimal Tradeoff Between Exposed and Hidden Nodes in Large Wireless Networks

Wireless networks equipped with the CSMA protocol are subject to collisions due to interference. For a given interference range we investigate the tradeoff between collisions (hidden nodes) and unused capacity (exposed nodes). We show that the sensing range that maximizes throughput critically depends on the activation rate of nodes. For infinite line networks, we prove the existence of a threshold: When the activation rate is below this threshold the optimal sensing range is small (to maximize spatial reuse). When the activation rate is above the threshold the optimal sensing range is just large enough to preclude all collisions. Simulations suggest that this threshold policy extends to more complex linear and non-linear topologies

Fresh look at randomly branched polymers

We develop a new, dynamical field theory of isotropic randomly branched polymers, and we use this model in conjunction with the renormalization group (RG) to study several prominent problems in the physics of these polymers. Our model provides an alternative vantage point to understand the swollen phase via dimensional reduction. We reveal a hidden Becchi-Rouet-Stora (BRS) symmetry of the model that describes the collapse ($\theta$-)transition to compact polymer-conformations, and calculate the critical exponents to 2-loop order. It turns out that the long-standing 1-loop results for these exponents are not entirely correct. A runaway of the RG flow indicates that the so-called $\theta^\prime$-transition could be a fluctuation induced first order transition.Comment: 4 page