Linear Relationship Statistics in Diffusion Limited Aggregation

We show that various surface parameters in two-dimensional diffusion limited aggregation (DLA) grow linearly with the number of particles. We find the ratio of the average length of the perimeter and the accessible perimeter of a DLA cluster together with its external perimeters to the cluster size, and define a microscopic schematic procedure for attachment of an incident new particle to the cluster. We measure the fractal dimension of the red sites (i.e., the sites upon cutting each of them splits the cluster) equal to that of the DLA cluster. It is also shown that the average number of the dead sites and the average number of the red sites have linear relationships with the cluster size.Comment: 4 pages, 5 figure

Uncertain Fiscal Consolidations

The paper explores the macroeconomic consequences of fiscal consolidations whose timing and composition are uncertain. Drawing on the evidence in Alesina and Ardagna (2010), we emphasize whether or not the fiscal consolidation is driven by tax rises or expenditure cuts. We find that the composition of the fiscal consolidation, its duration, the monetary policy stance, the level of government debt and expectations over the likelihood and composition of fiscal consolidations all matter in determining the extent to which a given consolidation is expansionary and/or successful in stabilizing government debt.

Bubble statistics and positioning in superhelically stressed DNA

We present a general framework to study the thermodynamic denaturation of double-stranded DNA under superhelical stress. We report calculations of position- and size-dependent opening probabilities for bubbles along the sequence. Our results are obtained from transfer-matrix solutions of the Zimm-Bragg model for unconstrained DNA and of a self-consistent linearization of the Benham model for superhelical DNA. The numerical efficiency of our method allows for the analysis of entire genomes and of random sequences of corresponding length ($10^6-10^9$ base pairs). We show that, at physiological conditions, opening in superhelical DNA is strongly cooperative with average bubble sizes of $10^2-10^3$ base pairs (bp), and orders of magnitude higher than in unconstrained DNA. In heterogeneous sequences, the average degree of base-pair opening is self-averaging, while bubble localization and statistics are dominated by sequence disorder. Compared to random sequences with identical GC-content, genomic DNA has a significantly increased probability to open large bubbles under superhelical stress. These bubbles are frequently located directly upstream of transcription start sites.Comment: to be appeared in Physical Review

Why Do Granular Materials Stiffen with Shear Rate? : Test of Novel Stress-Based Statistics

Peer reviewedPublisher PD

Parametric-based distribution duct routing generation using constraint-based design approach

In this paper, we present a generative design approach using constraint-based programming to handle the duct routing for ceiling mounted fan coil systems in buildings. This work utilises and builds on the result from previous approach using case-based reasoning and constraint satisfaction problem to deal with the space configuration of complex design problems for ceiling mounted fan coil systems in buildings. In this work, our approach automates the distribution routing using constraint-based approach. Comparatively to previous work, the system we have developed generates parametric-based models where further interactive modification and interaction is made possible for the end user. This approach has been tested in real case scenario working with our industrial partners

Function of monocytes in chronic HCV infection: Role for IL-10 and interferon

Hepatitis C virus (HCV) establishes persistent infection in about 80% of the infected individuals. The symptoms are initially mild in those persistently infected patients, and it may take decades before the serious consequences of chronic HCV infection become apparent. Up to 20% of infected individuals may develop complications, including cirrhosis, liver failure, or hepatocellular carcinoma [3]. HCV infection is now the leading indication for liver transplantation in the United States and Europe

VHE gamma ray absorption by galactic interstellar radiation field

Adopting a recent calculation of the Galactic interstellar radiation field, we calculate the attenuation of the very high energy gamma rays from the Galactic sources. The infra-red radiation background near the Galactic Center is very intense due to the new calculation and our result shows that a cutoff of high energy gamma ray spectrum begins at about 20 TeV and reaches about 10% for 50 TeV gamma rays.Comment: 6 pages, 1 figure, figure is changed, conclusion not change

Spectral properties of the 2D Holstein t-J model

Employing the Lanczos algorithm in combination with a kernel polynomial moment expansion (KPM) and the maximum entropy method (MEM), we show a way of calculating charge and spin excitations in the Holstein t-J model, including the full quantum nature of phonons. To analyze polaron band formation we evaluate the hole spectral function for a wide range of electron-phonon coupling strengths. For the first time, we present results for the optical conductivity of the 2D Holstein t-J model.Comment: 2 pages, Latex. Submitted to Physica C, Proc. Int. Conf. on M2HTSC

Study on thermal conductivity of gas phase in nano-porous aerogel

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Nano-porous aerogel has an ultra low thermal conductivity and is usually used as the super insulator. To evaluate the insulation performance of the aerogel, we focus on studying the thermal conductivity of gas phase in the aerogel. We present a modified model to take into account the effect of nonuniform pore-size distribution on the gaseous thermal conductivity, and the present model predicts more agreement results with available data than the existing models. The gaseous thermal conductivity of the aerogel at high temperature gradient condition is also numerically studied. We also study the effect of the thermal transpiration flow on the gaseous thermal conductivity, and the results shows that the thermal transpiration flow effect leads to a reduction of the gaseous thermal conductivity

Large-Scale Structure Shocks at Low and High Redshifts

Cosmological simulations show that, at the present time, a substantial fraction of the gas in the intergalactic medium (IGM) has been shock-heated to T>10^5 K. Here we develop an analytic model to describe the fraction of shocked, moderately overdense gas in the IGM. The model is an extension of the Press & Schechter (1974) description for the mass function of halos: we assume that large-scale structure shocks occur at a fixed overdensity during nonlinear collapse. This in turn allows us to compute the fraction of gas at a given redshift that has been shock-heated to a specified temperature. We show that, if strong shocks occur at turnaround, our model provides a reasonable description of the temperature distribution seen in cosmological simulations at z~0, although it does overestimate the importance of weak shocks. We then apply our model to shocks at high redshifts. We show that, before reionization, the thermal energy of the IGM is dominated by large-scale structure shocks (rather than virialized objects). These shocks can have a variety of effects, including stripping ~10% of the gas from dark matter minihalos, accelerating cosmic rays, and creating a diffuse radiation background from inverse Compton and cooling radiation. This radiation background develops before the first stars form and could have measurable effects on molecular hydrogen formation and the spin temperature of the 21 cm transition of neutral hydrogen. Finally, we show that shock-heating will also be directly detectable by redshifted 21 cm measurements of the neutral IGM in the young universe.Comment: 12 pages, 8 figures, submitted to Ap