TO TEACH COMBINATORICS, USING SELECTED PROBLEMS

In 1972, professor Grigore Moisil, the most famous Romanian academician for Mathematics, said about Combinatorics, that it is “an opportunity of a renewed gladness”, because “each problem in the domain asks for its solving, an expenditure without any economy of the human intelligence”. More, the research methods, used in Combinatorics, are different from a problem to the other! This is the explanation for the existence of my actual paper, in which I propose to teach Combinatorics, using selected problems. MS classification: 05A05, 97D50

A survey of DNA motif finding algorithms

Background: Unraveling the mechanisms that regulate gene expression is a major challenge in biology. An important task in this challenge is to identify regulatory elements, especially the binding sites in deoxyribonucleic acid (DNA) for transcription factors. These binding sites are short DNA segments that are called motifs. Recent advances in genome sequence availability and in high-throughput gene expression analysis technologies have allowed for the development of computational methods for motif finding. As a result, a large number of motif finding algorithms have been implemented and applied to various motif models over the past decade. This survey reviews the latest developments in DNA motif finding algorithms.Results: Earlier algorithms use promoter sequences of coregulated genes from single genome and search for statistically overrepresented motifs. Recent algorithms are designed to use phylogenetic footprinting or orthologous sequences and also an integrated approach where promoter sequences of coregulated genes and phylogenetic footprinting are used. All the algorithms studied have been reported to correctly detect the motifs that have been previously detected by laboratory experimental approaches, and some algorithms were able to find novel motifs. However, most of these motif finding algorithms have been shown to work successfully in yeast and other lower organisms, but perform significantly worse in higher organisms.Conclusion: Despite considerable efforts to date, DNA motif finding remains a complex challenge for biologists and computer scientists. Researchers have taken many different approaches in developing motif discovery tools and the progress made in this area of research is very encouraging. Performance comparison of different motif finding tools and identification of the best tools have proven to be a difficult task because tools are designed based on algorithms and motif models that are diverse and complex and our incomplete understanding of the biology of regulatory mechanism does not always provide adequate evaluation of underlying algorithms over motif models.Peer reviewedComputer Scienc

Challenges and limits of mechanical stability in 3D direct laser writing

Direct laser writing is an effective technique for fabrication of complex 3D polymer networks using ultrashort laser pulses. Practically, it remains a challenge to design and fabricate high performance materials with different functions that possess a combination of high strength, substantial ductility, and tailored functionality, in particular for small feature sizes. To date, it is difficult to obtain a time-resolved microscopic picture of the printing process in operando. To close this gap, we herewith present a molecular dynamics simulation approach to model direct laser writing and investigate the effect of writing condition and aspect ratio on the mechanical properties of the printed polymer network. We show that writing conditions provide a possibility to tune the mechanical properties and an optimum writing condition can be applied to fabricate structures with improved mechanical properties. We reveal that beyond the writing parameters, aspect ratio plays an important role to tune the stiffness of the printed structures

Forever starts now

Moms as historical perspectives, abstraction and image making; Through stoves, swimwear and carpets. Then, one hope- That one-day history will become yours and mine

Controlling the Mobility of Ionic Liquids in the Nanopores of MOFs by Adjusting the Pore Size: From Conduction Collapse by Mutual Pore Blocking to Unhindered Ion Transport

Ionic liquids (ILs) in nanoporous confinement are the core of many supercapacitors and batteries, where the mobility of the nanoconfined ILs is crucial. Here, by combining experiments based on impedance spectroscopy with molecular dynamics simulations, the mobility of a prototype IL in the nanopores of an isoreticular metal-organic framework (MOF)-series with different pore sizes is explored, where an external electric field is applied. It has been found that the conduction behavior changes tremendously depend on the pore size. For small-pore apertures, the IL cations and anions cannot pass the pore window simultaneously, causing the ions to mutually block the pores. This results in a strong concentration dependence of the ionic conduction, where the conduction drops by two orders of magnitude when filling the pores. For large-pore MOFs, the mutual hindrance of the ions in the pores is small, causing only a small concentration dependence. The cutoff between the large-pore and small-pore behavior is approximately the size of a cation-anion-dimer and increasing the pore diameter by only 0.2 nm changes the conduction behavior fundamentally. This study shows that the pore aperture size has a substantial effect on the mobility of ions in nanoporous confinement and has to be carefully optimized for realizing highly-mobile nanoconfined ILs

The possible inclusion of legal provisions in Islamic banking and finance: the case study of the Mozambican regulatory framework

Purpose: This paper aims to thoroughly examine the extent to which the current legal and regulatory framework is inclusive towards Islamic banking and finance (IBF) practices in the attempts to introduce IBF as a significant component in the Mozambique’s financial system. This is achieved by providing a critical review on the Mozambican current legal and regulatory framework including the court and arbitration system, as well as the country’s financial institutions law and regulations. Design/methodology/approach: The methodology used in this study is the qualitative approach. The analysis made is based on descriptive and analytical approach whereby the study examined and critically analysed the banking regulations in Mozambique with the purpose of finding the legal gap in the existing legal and regulatory framework that allows the introduction of IBF in the country. Findings: This study finds that whilst some legal provisions in the current legal and regulatory framework are conflicting with the Sharï’ah principles such as the definition of loans and the concept of interest, there is also a certain number of enabling features that can be immediately explored, including deposits (with no interest), leasing operations, investment funds or venture capital. Research limitations/implications: At present, to the best of the authors’ knowledge, this is the first attempt ever made to assess the compatibility of the existing Mozambican commercial laws with the Islamic principles hence identifying the challenges that might arise due to the implementation of IBF practices in Mozambique. Practical implications: This paper has several practical implications in the sense that it helps the financial market authorities in Mozambique to be able to foresee possible inclusion of provisions on Islamic transactions in the country’s existing financial regulations. Social implications: The contributions of this paper lie in the valuable recommendations made on the insertion of Islamic principles in the current regulatory framework as well as assisting in overcoming some of the conflicting aspects in medium to long term. Mozambique should explore and benefit from the experience and lessons learned by the neighbouring countries that have successfully adopted the IBF practice. It is recommended that the Central Bank should establish a “task force team”, comprising of multi-skilled professionals and experts in Islamic finance from various internal areas ranging from licensing to supervision together with Sharï’ah scholars and representatives from the Muslim Community, to study the required process for adoption of IBF in the country. Originality/value: There is no other study on IBF in Mozambique, particularly on legal and regulatory aspects