Nonlinear effects for island coarsening and stabilization during strained film heteroepitaxy

Nonlinear evolution of three-dimensional strained islands or quantum dots in heteroepitaxial thin films is studied via a continuum elasticity model and the development of a nonlinear dynamic equation governing the film morphological profile. All three regimes of island array evolution are identified and examined, including a film instability regime at early stage, a nonlinear coarsening regime at intermediate times, and the crossover to a saturated asymptotic state, with detailed behavior depending on film-substrate misfit strains but not qualitatively on finite system sizes. The phenomenon of island stabilization and saturation, which corresponds to the formation of steady but non-ordered arrays of strained quantum dots, occurs at later time for smaller misfit strain. It is found to be controlled by the strength of film-substrate wetting interaction which would constrain the valley-to-peak mass transport and hence the growth of island height, and also determined by the effect of elastic interaction between surface islands and the high-order strain energy of individual islands at late evolution stage. The results are compared to previous experimental and theoretical studies on quantum dots coarsening and saturation.Comment: 19 pages, 12 figures; submitted to Phys. Rev.

Improvement of chlorine stability by natural organic matter removal using a combination of biologically activated carbon with coagulation in drinking water treatment

This study focuses on the feasibility of biologically activated carbon (BAC) to enhance natural organic matter (NOM) removal by subsequent coagulation. This will reduce chlorine demand and it is expected that the removal would also reduce disinfection by-products (DBP). The NOM is a heterogeneous mixture of complex organic materials abundantly occurs in all natural water sources. These organic matters are the potential precursors for the formation of carcinogenic DBP and cause several other water quality problems. Aimed mainly at removing particles in the water, the coagulation process, the major conventional water treatment method, removes only a small amount of higher molecular weight (MW) fractions of NOM. To remove a higher amount of organic matter, larger doses of coagulant, such as ferric or aluminium salts, need to be added. In a normal water treatment plant, coagulation tank is followed by flocculation tank and sedimentation basin to remove the flocs formed. With the requirement to process water quickly, especially in the treatment of low turbidity water the sedimentation tank is avoided and only smaller doses of coagulant are applied and subjected to direct filtration, such as in treatment plants of Sydney Water. Hence, the challenge is to remove more NOM effectively and increase the chlorine stability without increasing the coagulant dose. The BAC process is a cost-effective and environmentally friendly water treatment method for removing biodegradable organic matters (BOM). It is used as a polishing step followed by coagulation or ozonation. It is well known that BAC removes NOM of hydrophilic nature and smaller MW which is less amenable to removal by the coagulation and many toxic and endocrine compounds which are not otherwise removed. In addition, it is known the biological activities increase soluble microbial products (SMP) which in turn helped in aiding the NOM removal by subsequent coagulation in recycled wastewater. The study, for the first time, explores the feasibility of using BAC as a pre-treatment of surface water to traditional coagulation process, equipped with direct filtration

The use of remote sensing data for drought assessment and monitoring in southwest Asia

Drought / Monitoring / Indicators / Assessment / Remote sensing / Asia

Interstitial cell network volume is reduced in the terminal bowel of ageing mice

Ageing is associated with impaired neuromuscular function of the terminal gastrointestinal (GI) tract, which can result in chronic constipation, faecal impaction and incontinence. Interstitial cells of cajal (ICC) play an important role in regulation of intestinal smooth muscle contraction. However, changes in ICC volume with age in the terminal GI tract (the anal canal including the anal sphincter region and rectum)have not been studied. Here, the distribution, morphology and network volume of ICC in the terminal GI tract of 3‐to 4‐month‐old and 26‐to 28‐month‐old C57BL/6mice were investigated. ICC were identified by immunofluorescence labelling of wholemount preparations with an antibody against c‐Kit. ICC network volume was measured by software‐based 3D volume rendering of confocal Z stacks. A significant reduction in ICC network volume per unit volume of muscle was measured in aged animals. No age‐associated change in ICC morphology was detected. The thickness of the circular muscle layer of the anal sphincter region and rectum increased with age, while that in the distal colon decreased. These results suggest that ageing is associated with a reduction in the network volume of ICC in the terminal GI tract, which may influence the normal function of these regions

Disability in the Workplace: Legal Barriers Affecting Human Resources Management Practices and Workplace Accommodation for the Persons with Disabilities in Sri Lanka - A Review of Literature

Disability can be defined as a physical or mental condition that barred such individual from properly interact with physical or social environment. This difficulty provided root course for historical marginalization of persons with disabilities in the society and visible in various fields ranging from education to employment and being analysed by various scholars. This literature review explores the question how various scholars approached the social political and legal issues arise out of low employment rate of the persons with disabilities and expressed their views on how to solve them. Since a systematic literature review has not been conducted in Sri Lanka on this topic, to answer the aforesaid research problem, author will evaluate multiple scholarly approaches towards the barriers affecting human resource practices and workplace accommodation for persons with disabilities and explore solutions available in the existing literature to resolve such issues. This research will be based on literature review methodology and first of such work in the field of disability rights in Sri Lanka. Thereby, results of this research will be produced by collecting and synthesizing previous research for advancing knowledge and facilitating theory development. However, literature survey was limited to the works which recently published in English language and meet certain scholarly standards. Keywords: Persons with Disabilities, Employment, Workplace Accommodation, Review of Literatur

Towards portable muography with small-area, gas-tight glass Resistive Plate Chambers

Imaging techniques that use atmospheric muons, collectively named under the neologism "muography", have seen a tremendous growth in recent times, mainly due to their diverse range of applications. The most well-known ones include but are not limited to: volcanology, archaeology, civil engineering, nuclear reactor monitoring, nuclear waste characterization, underground mapping, etc. These methods are based on the attenuation or deviation of muons to image large and/or dense objects where conventional techniques cannot work or their use becomes challenging. In this context, we have constructed a muography telescope based on "mini glass-RPC planes" following a design similar to the glass-RPC detectors developed by the CALICE Collaboration and used by the TOMUVOL experiment in the context of volcano radiography, but with smaller active area (16 $\times$ 16 cm$^{2}$). The compact size makes it an attractive choice with respect to other detectors previously employed for imaging on similar scales. An important innovation in this design is that the detectors are sealed. This makes the detector more portable and solves the usual safety and logistic issues for gas detectors operated underground and/or inside small rooms. This paper provides an overview on our guiding principles, the detector development and our operational experiences. Drawing on the lessons learnt from the first prototype, we also discuss our future direction for an improved second prototype, focusing primarily on a recently adopted serigraphy technique for the resistive coating of the glass plates.Comment: 8 pages, 7 figures, XV Workshop on Resistive Plate Chambers and Related Detectors (RPC2020

Design of holes and web openings in railway prestressed concrete sleepers

As the crosstie beam in railway track systems, the prestressed concrete sleepers (or railroad ties) are principally designed in order to carry wheel loads from the rails to the ground. Their design takes into account static and dynamic loading conditions. It is evident that prestressed concrete has played a significant role as to maintain the high endurance of the sleepers under low to moderate repeated impact loads. In spite of the most common use of the prestressed concrete sleepers in railway tracks, there have always been many demands from rail engineers to improve serviceability and functionality of concrete sleepers. For example, signalling, fibre optic, equipment cables are often damaged either by ballast corners or by tamping machine. There has been a need to re-design concrete sleeper to cater cables internally so that they would not experience detrimental or harsh environments. Accordingly, this study will investigate the design criteria and effects of holes and web openings on structural capacity of concrete sleepers under rail loading. The modified compression field theory for ultimate strength design of concrete sleepers will be highlighted in this study. The outcome of this study will enable the new design and calculation methods for prestressed concrete sleepers with holes and web opening that practically benefits civil, track and structural engineers in railway industry

Enforcing Information Flow Security Properties in Cyber-Physical Systems: A Generalized Framework Based on Compensation

This paper presents a general theory of event compensation as an information flow security enforcement mechanism for Cyber-Physical Systems (CPSs). The fundamental research problem being investigated is that externally observable events in modern CPSs have the propensity to divulge sensitive settings to adversaries, resulting in a confidentiality violation. This is a less studied yet emerging concern in modern system security. A viable method to mitigate such violations is to use information flow security based enforcement mechanisms since access control based security models cannot impose restrictions on information propagation. Further, the disjoint nature of security analysis is not appropriate for systems with highly integrated physical and cyber infrastructures. The proposed compensation based security framework is foundational work that unifies cyber and physical aspects of security through the shared semantics of information flow. A DC circuit example is presented to demonstrate this concept