Technological development in Therapeutic applications of alternating electric fields: Review

A number of bacteria, virus and other unhealthy cells need to be killed for getting rid of them. For more than a century antibiotics have been effectively used for killing bacterial pathogens and chemical drugs against the cancer cells. However, there are bacteria and cancer cells that are drug resistant. This may have to be overcome by other stronger drugs, higher dosage. These can have detrimental side effects. Other non drug methods to aid the effect of these drugs have always been in research. Electrochemotherapy, a method of using electric fields along with the drug to be used topically has been one of the successful approaches. One of the most recent methods of Tumor Treating Frequencies (TTF) for a brain cancer has been FDA approved. This article details the use of TTF. The article also details some other latest research where alternating fields are used as antibacterial agents

Effective active learning strategies I have used in University class room

In this paper I summarize the various activities used in class room and laboratory teaching of first and second year engineering. These activities can be grouped under ‘active learning’. I describe the activities and the various attributes associated with each activity along with the advantages of using the mentioned activity model instead of simply a single ended lecturing model. Although most of these have erupted from an urge to increase students learning while making the topics increasingly interesting for them, most of these strategies have been researched out globally as effective teaching practices. Traditionally lecturers may think that they are doing active learning when questions are asked and a few students always answer or discussions amongst the same group of people take place from time to time. Although this includes student participation, it is engaging only a small fraction of a big class which is not optimum in terms of benefit to the class as whole and individuals of the class. Active learning is taking place in your class when you ask a question, pose a problem, or throw some type of challenge at them; ask your students to work individually or in pairs or small groups to come up with a response; give them some set time to do it; stop them, and invite one or more individuals or groups to share their responses with the class. The teacher as an expert can further comment on the answer if required. This paper concludes with a number of proven methods of including active learning strategies in first and second year Physics/electronics engineering class. Reference to global research about these strategies is included

Teaching electric field topic with computer visualization

Electromagnetic field is undoubtedly one of the most difficult course in the undergraduate courses for electronics/physics degrees. The difficulty arises from the fact that electromagnetic fields are not visible unlike some other concepts in mechanical engineering where one deals with concrete objects. Students generally find it hard to grasp the ideas as these ideas are abstract and their learning cannot be supported through simple experiments in which they can handle objects and see what is happening. Visualisation of electric field lines and equipotential contours in several different scenarios can be demanding to imagine. There are mathematical ways to calculate however these methods can be equally or more challenging. For the first instance before mathematics of the electric fields is introduced if the electric field lines can be viewed as an output of a simple computer model it can be very beneficial to students for their understanding and retaining/creating their interest and enthusiasm in the subject. Since several parameters in the model can be changed very easily, effects of those parameters on electric field lines can be viewed. The main objective of this article is to demonstrate some such simple modelling possibilities using the available software package

Dynamic Electroporation Modelling

In this thesis, modelling and simulation of the effects of electric fields on a single spherical cell are undertaken. Of interest is the effect that different electric field waveforms have on the induced transmembrane potential of the cell and by consequence the electropermeabilization of the cell membrane in terms of pore density or the fraction of the cell area that the pores occupy. Conventional biotechnology processes of electroporation make use of unipolar electric field pulses, which are known to generate undesirable conditions such as asymmetrical electropermeabilization. These electrical protocols also contribute to lower efficiencies in electroporation based applications (in terms of uptake of molecules in the cell) by being sensitive to cell radii. Until recently, theoretical models of electroporation have lagged behind the experimental research. In order to optimize the efficiency of electroporation, it is important to consider as many biological and physical aspects as possible and it is a necessity that a variety of electric pulse parameters be tested. Thus a comprehensive model which can predict electropermeabilization as a result of any form of applied electric field and other important electroporation parameters is necessary. None of the existing theoretical modelling studies present simulations of dynamic electroporation modelling as a cell response to bipolar electric field wave-shapes. Developing such a model is the aim of this thesis. In this thesis two numerical models are developed. These models consider electroporation as a dynamic process and include the non-linear dynamic effects of membrane electropermeabilization. The first model assumes all pores are identical and small (0.76~nm radius) and is capable of simulating transmembrane potential and pore density temporally and spatially, given any form of applied electric field and other important electroporation system parameters such as external medium, membrane, and cytoplasm complex dielectric properties. The piece-wise step response model presented here is used to simulate cell response to several different applied electric field wave-shape pulses.% including a unipolar square wave, bipolar square wave, bipolar sine wave, bipolar rectangular wave (rectangular pulse train), and a bipolar triangular wave. Additional results from the first model demonstrate how the efficiency of electroporation related applications can be significantly improved by appropriately adjusting the parameters of the applied electric field and the extracellular conductivity. Emphasis is given on the normalization of the degree of electroporation (in terms of pore density) for two cell radii (7.5~$\mu$m and 15~$\mu$m). Although, these results gave a fair indication of the extent of electroporation in terms of pore density, the approximation that all pores have the same size, and do not change with time, may not be appropriate. There is a need to model electroporation so as to reflect the growth or shrinkage of pores with time, as well as efficiently handle arbitrary waveshapes of electric fields. The additional information about pore radius evolution gives a more realistic picture of the extent of electroporation, especially if one is to model for longer time (longer than 1~$\mu$s) or if an application necessarily required existence of larger pores (radius lager than 1~nm) rather than just the total pore area. Pore radius and pore numbers affect the transmembrane potential, which in turn affects pore density and pore radius. Literature includes information on spatial and temporal aspects of pore radius evolution. However, the electric fields used in these models were limited to unipolar DC pulses and details of temporal and spatial evolution of transmembrane potential and pore radius have not been reported. The second model developed in this thesis simulates spatial and temporal aspects of pore radius as an effect of any given form of applied electric field (including unipolar or bipolar), and other important electroporation system parameters. The transmembrane potential and pore radii as function of time and angular position about the cell membrane are presented. The results show that pore radii tend to be more normalized when an AC (bipolar) field is used when compared to a DC (unipolar) field (pore radii ranging from 1~nm to 8~nm for DC protocol compared with 1~nm to 3.4~nm for AC protocol when the pulse amplitude used in both cases is such as to give a similar fractional pore area at the end of 2~$\mu$s). Additional simulation results from this model are used to compare the extent of electroporation in response to sinusoidal AC (bipolar) electric field pulses of two different frequencies in a range of extracellular conductivity for two different cell radii (7.5~$\mu$m and 15~$\mu$m). It is observed that a higher frequency (1~MHz) bipolar sinusoidal applied electric field pulse reduces the relative difference in fractional pore area for the two cell sizes compared to a lower frequency (100~kHz) pulse. Nevertheless for the high frequency, a significantly higher amplitude is required to create the same level of average fractional pore area. Asymmetry of fractional pore area between the two hemispheres of the cell is observed for both field protocols

Semi-automated Software Requirements Categorisation using Machine Learning Algorithms

Requirement engineering is a mandatory phase of the Software development life cycle (SDLC) that includes defining and documenting system requirements in the Software Requirements Specification (SRS). As the complexity increases, it becomes difficult to categorise the requirements into functional and non-functional requirements. Presently, the dearth of automated techniques necessitates reliance on labour-intensive and time-consuming manual methods for this purpose. This research endeavours to address this gap by investigating and contrasting two prominent feature extraction techniques and their efficacy in automating the classification of requirements. Natural language processing methods are used in the text pre-processing phase, followed by the Term Frequency – Inverse Document Frequency (TF-IDF) and Word2Vec for feature extraction for further understanding. These features are used as input to the Machine Learning algorithms. This study compares existing machine learning algorithms and discusses their correctness in categorising the software requirements. In our study, we have assessed the algorithms Decision Tree (DT), Random Forest (RF), Logistic Regression (LR), Neural Network (NN), K-Nearest Neighbour (KNN) and Support Vector Machine (SVM) on the precision and accuracy parameters. The results obtained in this study showed that the TF-IDF feature selection algorithm performed better in categorising requirements than the Word2Vec algorithm, with an accuracy of 91.20% for the Support Vector Machine (SVM) and Random Forest algorithm as compared to 87.36% for the SVM algorithm. A 3.84% difference is seen between the two when applied to the publicly available PURE dataset. We believe these results will aid developers in building products that aid in requirement engineering

Modelling single cell electroporation with bipolar pulse parameters and dynamic pore radii

We develop a model of single spherical cell electroporation and simulate spatial and temporal aspects of the transmembrane potential and pore radii as an effect of any form of applied electric field. The extent of electroporation in response to sinusoidal electric pulses of two different frequencies in a range of extracellular conductivity for two different cell radii are compared. Results show that pore radii tend to be more normalized for AC fields. The relative difference in fractional pore area is reduced by the use of a 1 MHz sinusoidal applied electric field over a 100 kHz field

Directed Multicut with linearly ordered terminals

Motivated by an application in network security, we investigate the following "linear" case of Directed Mutlicut. Let $G$ be a directed graph which includes some distinguished vertices $t_1, \ldots, t_k$. What is the size of the smallest edge cut which eliminates all paths from $t_i$ to $t_j$ for all $i < j$? We show that this problem is fixed-parameter tractable when parametrized in the cutset size $p$ via an algorithm running in $O(4^p p n^4)$ time.Comment: 12 pages, 1 figur