scholarly journals Entropy Based Biological Sequence Study

2021 ◽  
Author(s):  
Bimal Kumar Sarkar

SARS-CoV-2 virus strains are taken into consideration for the analysis of digitized sequences of information by means of the notions of entropy. The occurrence of a particular pattern in the corona viral sequence is paid a special attention. The incidence of genetic word is represented in a density means. The incidence frequency of the q-gram genetic word is determined with the help of finite impulse response (FIR) filter along the sequence. It is in turn, used for the determination of the probability distribution of the genetic word incidence as the input for the calculation of entropy in the sequence. The sequence entropy is further used for principal component analysis (PCA) to determine the similarity/dissimilarity between the viral sequences. We have considered seven human corona virus sequences. Entropy based similarity study for SARS-CoV-2 strains is presented in this work.

2020 ◽  
Author(s):  
Mohamad Hushnie Haron ◽  
Mohd Nasir Taib ◽  
Nurlaila Ismail ◽  
Nor Azah Mohd Ali ◽  
Saiful Nizam Tajuddin

2020 ◽  
pp. 000370282096971
Author(s):  
Nataša Radosavljević Stevanović ◽  
Milena Jovanović ◽  
Federico Marini ◽  
Slavica Ražić

Heroin is one of the most frequently seized drugs in Southeastern Europe. Due to the position in the Balkan route, the Republic of Serbia keeps important role in suppression of the trafficking of heroin for domestic and foreign illegal market. This research is aimed to provide a good scientific approach in the field of seized heroin analysis. Two different forms of heroin are present in the illegal market, mostly in mixtures with typical “cutting” agents: caffeine, paracetamol, and sugars. It was observed that the quantity of pure heroin in seized samples slightly increases from year to year. The aim of this study was to produce a reliable and fast procedure for classification of illicit heroin samples and determination of the concentration range of heroin in the samples. For that purpose, the attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) technique was used and combined with such chemometric methods as principal component analysis, cluster analysis, and partial least squares. Principal component analysis (PCA) as an unsupervised model was used for exploratory purposes to identify trends, similarities, and differences between samples by reducing the dimensionality of the data. The cluster classification of examined samples turned out to be extremely useful to evaluate the possibilities of the ATR FT-IR technique to classify the samples appropriately into the patterns, the constituted clusters. Additionally, partial least square was the suitable method for the purpose of determination of the heroin hydrochloride concentration range in examined samples. It is proved that the joined application of spectroscopy and chemometrics can be extremely convenient and useful for forensic and drugs control laboratories.


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