Emergence of Order in Textured Patterns

A characterization of textured patterns, referred to as the disorder function \bar\delta(\beta), is used to study properties of patterns generated in the Swift-Hohenberg equation (SHE). It is shown to be an intensive, configuration-independent measure. The evolution of random initial states under the SHE exhibits two stages of relaxation. The initial phase, where local striped domains emerge from a noisy background, is quantified by a power law decay \bar\delta(\beta) \sim t^{-{1/2} \beta}. Beyond a sharp transition a slower power law decay of \bar\delta(\beta), which corresponds to the coarsening of striped domains, is observed. The transition between the phases advances as the system is driven further from the onset of patterns, and suitable scaling of time and \bar\delta(\beta) leads to the collapse of distinct curves. The decay of $\bar\delta(\beta)$ during the initial phase remains unchanged when nonvariational terms are added to the underlying equations, suggesting the possibility of observing it in experimental systems. In contrast, the rate of relaxation during domain coarsening increases with the coefficient of the nonvariational term.Comment: 9 Pages, 8 Postscript Figures, 3 gif Figure

Universal bifurcation property of two- or higher-dimensional dissipative systems in parameter space: Why does 1D symbolic dynamics work so well?

The universal bifurcation property of the H\'enon map in parameter space is studied with symbolic dynamics. The universal-$L$ region is defined to characterize the bifurcation universality. It is found that the universal-$L$ region for relative small $L$ is not restricted to very small $b$ values. These results show that it is also a universal phenomenon that universal sequences with short period can be found in many nonlinear dissipative systems.Comment: 10 pages, figures can be obtained from the author, will appeared in J. Phys.

Symmetry Decomposition of Chaotic Dynamics

Discrete symmetries of dynamical flows give rise to relations between periodic orbits, reduce the dynamics to a fundamental domain, and lead to factorizations of zeta functions. These factorizations in turn reduce the labor and improve the convergence of cycle expansions for classical and quantum spectra associated with the flow. In this paper the general formalism is developed, with the $N$-disk pinball model used as a concrete example and a series of physically interesting cases worked out in detail.Comment: CYCLER Paper 93mar01

Water Quality in Selected Locations of the Kalu Ganga

Out of the 103 rivers in the country Kalu Ganga is one of the main rivers in Sri Lanka with a length of 129km and a drainage area of 2720 km2. It has the highest discharge volume with a mean annual discharge volume to sea totaling to 8183 mcm.  Kalu Ganga originates from the central hills of mountain Sri Pada situated 2100 m above sea level and falls to the sea in Kalutara.The purpose of this research is to analyze the current water quality situation of the Kalu Ganga River and its suitability for  human consumption purposes (by comparing with the CEA and SLS standards). It is also the purpose of this research to locate the areas where the river is exposed to massive degradation in water quality and identify the main sources of pollution in those areas.The research study was conducted in the middle and lower reaches of the Kalu Ganga basin. The study was conducted in two phases, the feasibility phase and the detail phase. The water quality of the river was tested using physical, chemical and biological parameters. The water samples from the relevant sampling points were obtained and analyzed in the period between February 2012 and August 2012. For the feasibility study, 13 sampling locations were selected along the main river and at locations where certain tributaries fall to the main river. The sampling points were in a stretch from Ratnapura to Kalutara with approximate distance of about 6-8 km from each sampling point to another. The sampling points for the feasibility study was selected based on  criteria such as regional population, land use pattern along the river basin, water intake points of the NWS&DB and previous studies. The parameters tested in the feasibility study were temperature, turbidity, TDS, E. Conductivity, pH, Chloride, Floride, Nitrate, Nitrite, Sulphate, Total Iron, Total Phosphate, Total hardness, Alkalinity, Heavy Metals, COD, BOD, DO, Total coli form and  E.coli.  The detail study was conducted based on the results of the feasibility study.Based on the results obtained the temperature of the river had an average value of 24̊   C and the pH values were within the range allowed in the CEA standard in most of the locations. The DO levels of the water was greater than the standard values while the BOD values in the river was lower than the standard value prescribed by the CEA standards. The COD values were comparatively higher in the river outfall (46.2mg/l) and in the Nathupana bridge (14.4mg/l) due to the industries located in the surrounding area, but the values were within the standard prescribed by the CEA. The river was not polluted much with the presence of heavy metals. The total coliform count was well below the standard level, while the fecal coliform count was above the standard level especially during the high flow period mainly in sampling points near tributaries. Based on the results obtained from the feasibility study it was decided to concentrate the detail study in the lower reaches of the middle basin and the lower basin of the main river. The sampling points were  located in areas from Horana to Kalutara. When selecting sampling points major effluent discharging industries in the river basin were selected as additional sampling points, to identify the affect of the final effluent on the water quality of the river. In total 11 sampling points were selected for the detail study. In the detail study certain parameters tested in the feasibility study was excluded due to tested results being lower than the minimum allowable levels in the standards. New parameters were included in the detail study based on the industries selected. The newly included parameters were free ammonia, color, sulphides, TOC, oil and grease, surfactants, phenolitic compounds and PAH.Keywords: Water quality, BOD, COD, industry effluent

Urea-Hydroxyapatite Nanohybrids for Slow Release of Nitrogen

While slow release of chemicals has been widely applied for drug delivery, little work has been done on using this general nanotechnology-based principle for delivering nutrients to crops. In developing countries, the cost of fertilizers can be significant and is often the limiting factor for food supply. Thus, it is important to develop technologies that minimize the cost of fertilizers through efficient and targeted delivery. Urea is a rich source of nitrogen and therefore a commonly used fertilizer. We focus our work on the synthesis of environmentally benign nanoparticles carrying urea as the crop nutrient that can be released in a programmed manner for use as a nanofertilizer. In this study, the high solubility of urea molecules has been reduced by incorporating it into a matrix of hydroxyapatite nanoparticles. Hydroxyapatite nanoparticles have been selected due to their excellent biocompatibility while acting as a rich phosphorus source. In addition, the high surface area offered by nanoparticles allows binding of a large amount of urea molecules. The method reported here is simple and scalable, allowing the synthesis of a urea-modified hydroxyapatite nanohybrid as fertilizer having a ratio of urea to hydroxyapatite of 6:1 by weight. Specifically, a nanohybrid suspension was synthesized by $\textit{in situ}$ coating of hydroxyapatite with urea at the nanoscale. In addition to the stabilization imparted due to the high surface area to volume ratio of the nanoparticles, supplementary stabilization leading to high loading of urea was provided by flash drying the suspension to obtain a solid nanohybrid. This nanohybrid with a nitrogen weight of 40% provides a platform for its slow release. Its potential application in agriculture to maintain yield and reduce the amount of urea used is demonstrated.Authors thank Hayleys Agro Ltd., Sri Lanka for initiating this research programme at SLINTEC and Nagarjuna Fertilizer and Chemical Ltd (NFCL), India for providing further support. Authors acknowledge Mr Sunanda Gunesekara of SLINTEC for assistance with scaling up the production process to enable the field trials. ARK acknowledges the financial support received from ICTPELETTRA Users Program, Trieste, Italy to conduct photoemission experiments at Materials Science beam line (MSB) and ELETTRA SRS on HA and urea coated HA samples. ARK further acknowledges Dr. R.G. Acres of MSB beam line for his extensive support to conduct photoemission experiments. We acknowledge the Department of Agriculture and Rice Research and Development Institute of Sri Lanka, in particular Dr Priyantha Weerasinghe, Mr D Sirisena and Dr Amitha Benthota for the assistance in carrying out pot and farmers filed trials. NFCL and Central Salt & Marine Chemicals Research Institute, Gujarat, India for TEM and BET analysis

Renormalization group approach to multiscale modelling in materials science

Dendritic growth, and the formation of material microstructure in general, necessarily involves a wide range of length scales from the atomic up to sample dimensions. The phase field approach of Langer, enhanced by optimal asymptotic methods and adaptive mesh refinement, copes with this range of scales, and provides an effective way to move phase boundaries. However, it fails to preserve memory of the underlying crystallographic anisotropy, and thus is ill-suited for problems involving defects or elasticity. The phase field crystal (PFC) equation-- a conserving analogue of the Hohenberg-Swift equation --is a phase field equation with periodic solutions that represent the atomic density. It can natively model elasticity, the formation of solid phases, and accurately reproduces the nonequilibrium dynamics of phase transitions in real materials. However, the PFC models matter at the atomic scale, rendering it unsuitable for coping with the range of length scales in problems of serious interest. Here, we show that a computationally-efficient multiscale approach to the PFC can be developed systematically by using the renormalization group or equivalent techniques to derive appropriate coarse-grained coupled phase and amplitude equations, which are suitable for solution by adaptive mesh refinement algorithms

Two new plant nutrient nanocomposites based on urea coated hydroxyapatite: Efficacy and plant uptake

Macronutrient delivery to plants, particularly nitrogen, is problematic because of losses occurring during fertilization. Currently, nanotechnology is being considered as a solution to improving nutrient use efficiency. In this study, we report the synthesis and plant uptake of two plant nutrient nanocomposites based on urea coated hydroxyapatite (UHA) and potassium encapsulated into (i) a nanoclay, montmorillonite (MMT) or (ii) cavities present in Gliricidia sepium stem resulting in a wood chip containing macronutrients. Soil leaching behaviour, efficacy and plant uptake of the nutrients were tested in a pot experiment using Festuca arundinacea during a period of 60 weeks. Two nanocomposites displayed slow release behaviour particularly for nitrogen, in soil leaching tests compared to the conventional formulations. Both nanoformulations displayed efficient plant nutrient uptake highlighting the improved nutrient use efficiency. These data clearly revealed that urea fabricated into its nanoscale provide platform for development of efficient fertilizer formulations

Pattern formation in 2-frequency forced parametric waves

We present an experimental investigation of superlattice patterns generated on the surface of a fluid via parametric forcing with 2 commensurate frequencies. The spatio-temporal behavior of 4 qualitatively different types of superlattice patterns is described in detail. These states are generated via a number of different 3--wave resonant interactions. They occur either as symmetry--breaking bifurcations of hexagonal patterns composed of a single unstable mode or via nonlinear interactions between the two primary unstable modes generated by the two forcing frequencies. A coherent picture of these states together with the phase space in which they appear is presented. In addition, we describe a number of new superlattice states generated by 4--wave interactions that arise when symmetry constraints rule out 3--wave resonances.Comment: The paper contains 34 pages and 53 figures and provides an extensive review of both the theoretical and experimental work peformed in this syste

"I just keep thinking that I don't want to rely on people." a qualitative study of how people living with dementia achieve and maintain independence at home: stakeholder perspectives

YesBACKGROUND: Most people living with dementia want to remain in their own homes, supported by family and paid carers. Care at home often breaks down, necessitating transition to a care home and existing interventions are limited. To inform the development of psychosocial interventions to enable people with dementia to live well for longer at home, we qualitatively explored the views of people living with dementia, family carers and health and social care professionals, on how to achieve and maintain independence at home and what impedes this. METHODS: We conducted an inductive thematic analysis of qualitative interviews with 11 people living with dementia, 19 professionals and 22 family carers in England. RESULTS: We identified four overarching themes: being in a safe and familiar environment, enabling not disabling care, maintaining relationships and community connectedness, and getting the right support. For people living with dementia, the realities of staying active were complex: there was a tension between accepting support that enabled independence and a feeling that in doing so they were accepting dependency. Their and professionals' accounts prioritised autonomy and 'living well with dementia', while family carers prioritised avoiding harm. Professionals promoted positive risk-taking and facilitating independence, whereas family carers often felt they were left holding this risk. DISCUSSION: Psychosocial interventions must accommodate tensions between positive risk-taking and avoiding harm, facilitating autonomy and providing support. They should be adaptive and collaborative, combining self-management with flexible support. Compassionate implementation of rights-based dementia care must consider the emotional burden for family carers of supporting someone to live positively with risk.This work was supported by the Alzheimer’s Society (UK) and was carried out within the UCL Alzheimer’s Society Centre of Excellence for Independence at home, NIDUS (New Interventions in Dementia Study) programme (Alzheimer’s Society Centre of Excellence grant 330). This project is also part-funded funded by The National Institute for Health Research Applied Research Collaboration North West Coast (ARC NWC)