Erosion waves: transverse instabilities and fingering

Two laboratory scale experiments of dry and under-water avalanches of non-cohesive granular materials are investigated. We trigger solitary waves and study the conditions under which the front is transversally stable. We show the existence of a linear instability followed by a coarsening dynamics and finally the onset of a fingering pattern. Due to the different operating conditions, both experiments strongly differ by the spatial and time scales involved. Nevertheless, the quantitative agreement between the stability diagram, the wavelengths selected and the avalanche morphology reveals a common scenario for an erosion/deposition process.Comment: 4 pages, 6 figures, submitted to PR

Urban development and visual culture: Commodifying the gaze in the regeneration of Tigné Point, Malta

This paper explores some of the hitherto under-researched intersections between urban (re)development, urban planning and visual culture. What emerges is an academic context that, to date, has largely compartmentalised discrete literatures on ‘view’, ‘value of the view’ and cityscape change, (re)Imagineering and (re)scripting). It shows how materialising processes associated with the commodification of a panoramic view in politico-economic and cultural terms can be used to transform and regenerate along neoliberal lines. It demonstrates how panoramas, when treated as a commodity within the context of neoliberal capitalism, are appropriated, (re)imagined and (re)scripted by architects and property developers to create high status, residential and commercial space for an affluent élite. As such, panoramas are a mechanism for the acceleration of capital accumulation that inherently create new and reinforce existing spatial inequalities. This study draws on research into the commodification of the view of the historic city of Valletta in the redevelopment of Tigné Point, the largest, most comprehensive regeneration scheme in Malta in recent years

Parametric estimation of the immunes proportion based on BCH model and exponential distribution using left censored data.

In population based cancer clinical trials, a proportion of patients will never experience the interested event and considered as "cured" or "immunes". The majority of recent cancer studies focus on the estimation of immune proportion. In this study we investigated the estimation of proportion of patients curd of cancer in case of left censored data based on the Bounded Cumulative Hazard (BCH) model proposed by Chen in 1999. The analysis provided the Maximum Likelihood Estimation (MLE) of the parameters within the framework of the Expectation Maximization (EM) algorithm where the numerical solutions of the estimation equations of the cure rate parameter could be employed

Parameter estimation of the cure fraction based on BCH model using left-censored data with covariates.

Medical investigations nowadays allow the incorporation of cure individuals in the analysis, especially for chronic diseases such as cancer. Therefore, survival models that incorporate the cured patients in the analysis are called cure rate models. In this paper, we propose an analytical approach for parametric estimation of the cure fraction in cancer clinical trials based on the bounded cumulative hazard (BCH) model with covariates involved in the data set. The analysis is constructed by means of the exponential distribution in the case of left censoring and within the framework of the expectation maximization (EM) algorithm. The analysis provided the analytical solution and a simulation study for the cure rate parameter

A constitutive law for dense granular flows

A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.Comment: http://www.nature.com/nature/journal/v441/n7094/abs/nature04801.htm

The Impact of the Gold Mining on the Social, Economic, Andcultural in the Bombana District Southeast Sulawesi Province

The phenomenon of a gold mine brings a lot of changes in people's daily life in the Bombana District. This study aims to: (a) Aware of the social and cultural changes in society before and after the gold mining business, and (b) Knowing the changes in people's income before and after the gold mining business. The study population is the people who are in the gold mining sites. This study result, namely: (a) Gold mining have negative impact on social, economic, and cultural of communities around the gold mining area. Social, economic, and cultural societies tend to be in better shape before the gold mining. Average income communities after the gold mining increase by Rp 755.392 per month. (c) Gold mining do not increase the welfare of society, especially for farmers. The implication of this study is the government should strictly supervise and tighten even a moratorium against IUP, and gold mining companies should have corporate social responsibility (CSR) in the form of incentives to the affected communities of the businesses under their management in the fields of education, health, agriculture, economics, and culture as well as other aspects relating to the welfare of society

Granular Solid Hydrodynamics

Granular elasticity, an elasticity theory useful for calculating static stress distribution in granular media, is generalized to the dynamic case by including the plastic contribution of the strain. A complete hydrodynamic theory is derived based on the hypothesis that granular medium turns transiently elastic when deformed. This theory includes both the true and the granular temperatures, and employs a free energy expression that encapsulates a full jamming phase diagram, in the space spanned by pressure, shear stress, density and granular temperature. For the special case of stationary granular temperatures, the derived hydrodynamic theory reduces to {\em hypoplasticity}, a state-of-the-art engineering model.Comment: 42 pages 3 fi

Patterns and Collective Behavior in Granular Media: Theoretical Concepts

Granular materials are ubiquitous in our daily lives. While they have been a subject of intensive engineering research for centuries, in the last decade granular matter attracted significant attention of physicists. Yet despite a major efforts by many groups, the theoretical description of granular systems remains largely a plethora of different, often contradicting concepts and approaches. Authors give an overview of various theoretical models emerged in the physics of granular matter, with the focus on the onset of collective behavior and pattern formation. Their aim is two-fold: to identify general principles common for granular systems and other complex non-equilibrium systems, and to elucidate important distinctions between collective behavior in granular and continuum pattern-forming systems.Comment: Submitted to Reviews of Modern Physics. Full text with figures (2Mb pdf) avaliable at http://mti.msd.anl.gov/AransonTsimringReview/aranson_tsimring.pdf Community responce is appreciated. Comments/suggestions send to [email protected]

Quantitative imaging of concentrated suspensions under flow

We review recent advances in imaging the flow of concentrated suspensions, focussing on the use of confocal microscopy to obtain time-resolved information on the single-particle level in these systems. After motivating the need for quantitative (confocal) imaging in suspension rheology, we briefly describe the particles, sample environments, microscopy tools and analysis algorithms needed to perform this kind of experiments. The second part of the review focusses on microscopic aspects of the flow of concentrated model hard-sphere-like suspensions, and the relation to non-linear rheological phenomena such as yielding, shear localization, wall slip and shear-induced ordering. Both Brownian and non-Brownian systems will be described. We show how quantitative imaging can improve our understanding of the connection between microscopic dynamics and bulk flow.Comment: Review on imaging hard-sphere suspensions, incl summary of methodology. Submitted for special volume 'High Solid Dispersions' ed. M. Cloitre, Vol. xx of 'Advances and Polymer Science' (Springer, Berlin, 2009); 22 pages, 16 fig