A simple model for DNA denaturation

Following Poland and Scheraga, we consider a simplified model for the denaturation transition of DNA. The two strands are modeled as interacting polymer chains. The attractive interactions, which mimic the pairing between the four bases, are reduced to a single short range binding term. Furthermore, base-pair misalignments are forbidden, implying that this binding term exists only for corresponding (same curvilinear abscissae) monomers of the two chains. We take into account the excluded volume repulsion between monomers of the two chains, but neglect intra-chain repulsion. We find that the excluded volume term generates an effective repulsive interaction between the chains, which decays as $1/r^{d-2}$. Due to this long-range repulsion between the chains, the denaturation transition is first order in any dimension, in agreement with previous studies.Comment: 10 page

Barrier and Sacrificial Protection Mechanisms of Zinc Rich Primers

A specific type of Zinc-Rich Paint was scratched and exposed in salt fog chamber for various exposure times up to 1,000 hours. The corrosion products that developed within the scratched region were studied by optical microscopy, scanning electron microscopy, and Electrochemical Impedance Spectroscopy (EIS). Bode plots were used to obtain the total resistance of the coating by salt spray exposure time. The results suggest that the mechanism of protection of zinc rich paints may not be simply as only sacrificial action followed by only barrier action, but rather an iteration of these two mechanisms exist. Although at very short times, prior to deposition of zinc corrosion products in the scratch, sacrificial action is the only mechanism of protection, once the corrosion products start to form there is a conjunction of the two protection actions with one dominating from time to time. This dual protection mechanism continues until all the available free zinc within the throwing power distance of the scratch has been consumed, at which point only barrier protection remains in action

Investigating the nature of passive films on austenitic stainless steels

Ph.DDOCTOR OF PHILOSOPH

Bacterial pathogens in conjunctivitis and corneal ulcers with special reference to Streptococcus pneumoniae, in early 2008, in the National Eye Hospital, Sri Lanka

Introduction: The most important and frequently occurring eye infections are conjunctivitis and corneal ulcers. Though the significance of Streptococcus pneumoniae in eye infections is well-known, identification of causative serotypes is important for comparison with serotypes causing invasive diseases. Objectives: To describe the spectrum and characteristics of bacterial pathogens associated with conjunctivitis and corneal ulcers with special reference to S. pneumoniae.Methods: A descriptive cross-sectional study was carried out from January to April 2008 in which samples were collected from patients above one month old with suspected conjunctivitis or corneal ulcers seen in the out-patients department and wards of the National Eye Hospital, Colombo, Sri Lanka. Both eye swabs (n=322) and corneal buttons (n=31) were cultured. Isolated bacteriawere identified as far as possible and antibiotic sensitivity testing done. S. pneumoniae isolates were stored in sheep blood agar slants at -70 ºC and serotyped. Results: There were 296 conjunctival swabs and 26 corneal swabs. From 296 conjunctival swabs 118 (39.8%) samples yielded no bacterial growth. There were 185 bacterial isolates from 159 significant positive samples. The most frequently isolated bacteria were coagulase negative Staphylococcus sp. (n=58: 31.4%), and second commonest was S. pneumoniae (n=33: 17.84%). From 57 samples from patients with corneal ulcers, 47 (82%) did not yield any bacterial growth. Sensitivity to chloramphenicol was high among Staphylococcus sp., S. pneumoniae, Haemophilus influenzae, Moraxella sp and coliforms. Among pneumococcal isolates serotyped, 19F was predominant. Conclusion: Coagulase negative staphylococci were predominantly isolated from eye swabs and corneal buttons, but the most significant frequent isolate was S. pneumoniae. Except Pseudomonas, &gt;90% isolates were sensitive to chloramphenicol. The predominant pneumococcal serotype was 19F.</p

Influential Factors for ICT Innovations in Sri Lanka University-Industry Collaboration: A Systematic Literature Review

A university is a center of knowledge creation, and industry can be a vibrant place for innovation. This paper examines the key factors influencing university-industry collaboration (UIC) innovation catalysts in Sri Lanka. The study employed a systematic procedure based on the Grounded Theory to investigate the factors contributing to the success of UICs, and attributes for innovation capacities. The investigation was guided by the research question: what factors of UICs influence ICT innovations in Sri Lanka? A total of 41 research papers was selected from Science Direct, Scopus, and Ebscohost based on the availability of full text, and their relevance for the research question. The results of the study revealed that management directives, financial support, policies, proximity dimension, and heterogeneity are key factors for a successful UIC

Volumetric quantitative optical coherence elastography with an iterative inversion method

It is widely accepted that accurate mechanical properties of three-dimensional soft tissues and cellular samples are not available on the microscale. Current methods based on optical coherence elastography can measure displacements at the necessary resolution, and over the volumes required for this task. However, in converting this data to maps of elastic properties, they often impose assumptions regarding homogeneity in stress or elastic properties that are violated in most realistic scenarios. Here, we introduce novel, rigorous, and computationally efficient inverse problem techniques that do not make these assumptions, to realize quantitative volumetric elasticity imaging on the microscale. Specifically, we iteratively solve the three-dimensional elasticity inverse problem using displacement maps obtained from compression optical coherence elastography. This is made computationally feasible with adaptive mesh refinement and domain decomposition methods. By employing a transparent, compliant surface layer with known shear modulus as a reference for the measurement, absolute shear modulus values are produced within a millimeter-scale sample volume. We demonstrate the method on phantoms, on a breast cancer sample ex vivo, and on human skin in vivo. Quantitative elastography on this length scale will find wide application in cell biology, tissue engineering and medicine.Publisher PDFPeer reviewe

Algae removal by roughing filter

Algae removal by roughing filte

Ultrasound morphology of carotid plaque and its link with lipid: protein content and 3d microstructure of the plaque.

the 22nd Meeting of the European Society of Neurosonology and Cerebral Hemodynamics (ESNCH), 19-21 May 2017. Berlin, Germany, and published in the International Journal of Stroke 12(1S): 57 (Poster 101), May 2017. ISSN: 1747-4930, eISSN: 1747-4949

A Comparative Study of Demand for Medical Care on Non Communicable Diseases: Western vs. Alternative

Medical care is an input to the production of health. People get treatment for their health issues under western medicine , complementary and alternative medicine. Western medicine can be identified as the most famous and modern medical care system in the world. Complementary and alternative medicine refers to avariety of health practices as ayurveda, homeopathy, acupuncture, herbs, yoga, etc . Considering Sri Lankan context, with the rapid increase of ageing population, there is a growing trend in non communicable diseases. Most of people tend to use these two systems to recover from non communicable diseases asasthma, cholesterol, hypertension, arthritis, etc. The main objective of this study was to distinguish between the demand for alternative medicine and western medicine related to non communicable diseases. It was considered socio demographic and economic factors for demand in medical care for both sectors. Primary data was based on Arogya private hospital and Siddhayurvedini private ayurvedic care institution in Gampaha. It was selected 100 non communicable disease patients using systematic sampling method. Logistic regression model was mainly used to distinguish between the alternative and western medical care. According to the findings of this study, females are more likely to demand for both medical cares. Middle age, unemployed, arthritis patient and duration of disease 2-5 years cause to raise demand for alternative medical care. Diabetic patient, employed, believing health status as serious and having employer provided insurance cause to raise demand for western medical care. Relative to the demand for alternative medical care, living in rural area and lower educated people are negatively associated with demand for western medical care.KEYWORDS: Demand, Western, alternative, non communicable disease