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Scholar@UOC is the primary academic repository of the University of Calicut.

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Recent Submissions

A statistical and analytical exploration of some generalized queueing systems with phase type distribution
(Department of Statistics, University of Calicut, 2026) Salima, P; Manoharan, M
Queueing systems with vacation policies effectively model service systems where servers may be temporarily unavailable due to rest, maintenance, or operational interruptions. These manufacturing, models computer are widely systems, and applicable in service communication networks, industries. Incorporating vacation mechanisms enhances realism and allows for better performance analysis, making such models critical for understanding and improving real world service systems. This thesis presents a comprehensive analytical and inferential investigation of single server queueing models with phase-type service and vacation time distributions. A Geo/PH/1 queue with multiple adaptive vacations is analyzed in discrete time, while an M/PH/1 queue with random vacations is examined in continuous time. Phase-type distributions provide flexibility while retaining analytical tractability. Both classical and Bayesian inference approaches are developed for parameter estimation. Classical inference is performed using maximum likelihood estimation via the expectation–maximization algorithm, while Bayesian inference is carried out using Markov chain Monte Carlo techniques with Gibbs sampling. Sensitivity analysis is conducted to assess the robustness of Bayesian estimates. Numerical investigations based on simulated data, along with real data applications, validate the analytical results. Key performance measures, including system utilization, queue length, waiting time, and busy period, are evaluated to demonstrate the impact of vacation policies. The thesis concludes by emphasizing the importance of vacation queueing models in practical service systems and by providing meaningful insights and directions for future research. Keywords: Vacation queueing models, Phase-type distributions, Discrete and continuous time queues, Performance measures, Maximum likelihood estimation, Bayesian inference.
Data analysis of common dyslipidemias for better clinical interpretation calculations of reference or cut off levels and relative prevalence
(Amala Cancer Research Centre, 2026) Shaima C M; Jose Jacob
Dyslipidemias are characterized by abnormal concentrations of cholesterol and triglycerides in plasma lipoproteins, typically resulting from disorders in lipoprotein metabolism. In this study, we are collecting clinical biochemistry data related to dyslipidemia from hospital. The data are analyzed and interpreted clinically by dividing them into gender and age-specific groups. This partitioning helps determine (a) proportion of patients with abnormal lipid profile, (b) gender-based differences, (c) reference intervals, and (d) the distribution patterns among the various subgroups. Lipid profiles were categorized into normal, isolated increases or decreases, and combined increases or decreases of four lipid components: serum triglycerides, total cholesterol, LDL-cholesterol, and HDL- Cholesterol. Our analysis includes assessing correlations, distributions, and variance to establish reference levels and the relative prevalence of common dyslipidemias observed in this hospital population. Data analyses of 15,603 lipid profile samples were done. Out of total 15,603 samples; there were 97 male samples and 86 female samples <18 years of age. There were 369 samples between age group 18 – 25 years. Out of which, there were 210 male samples and 159 female samples. The number of samples between 26 – 50 years was 5168. Out of which, there were 3247 male samples and 1921 female samples in the age group 26 – 50 years. The number of samples in age group >50 years was 9883. Out of which, there were 5925 male samples and 3958 female samples. Approximately 84% of general population in age group between 26 – 50 years, covered in this study have abnormalities in at least one of the lipid profile parameters analyzed. Most prevalent dyslipidemia is Isolated HDL- C decrease in males and females of all age groups except 26 – 50 years. In 26 – 50 years males, the most prevalent dyslipidemia is Isolated Serum triglyceride increase. But in females, Combined LDL-C and Total Cholesterol increase is the most prevalent dyslipidemia. Triglycerides >885mg/dL is the rare form of dyslipidemia. The proportion of patients with dyslipidemia is highest in males of 26 – 50 years. The healthiest lipid profile was observed in the age group females <18years. The study employed statistical and graphical methods, including Histograms, Box-Whisker plots, and Normal Q-Q plots, to analyze and classify lipid profile parameters such as Total Cholesterol (TC), Serum Triglycerides (TG), HDL Cholesterol (HDL-C), and LDL Cholesterol (LDL–C). Histograms and Normal Q-Q plots revealed a positive skew in Total Cholesterol and Triglyceride distributions, and Box-Whisker plots helped identify outliers, which were furthercategorized into near and far outliers. These graphical tools were used not only for statistical interpretation but also to clinically differentiate common, multifactorial dyslipidemias from rare, severe monogenic forms. Correlation analysis showed that triglycerides positively correlated with glucose, Total Cholesterol, LDL–C, TSH, and BMI in adult males. While in females, Triglycerides positively associated with liver enzymes AST and ALKP, possibly due to sex-related hormonal differences. Triglyceride was inversely correlated with HDL – C in both sexes. Total Cholesterol positively correlated with LDL–C. The reference intervals for various lipid profile analytes across different gender and age groups were analysed. Due to the positive skewness of the data, the 90% reference interval calculation was deemed the most appropriate. For example, In female individuals aged 18 to 25 years, the 90% reference interval values were as: Total Cholesterol: 119.83 mg/dL (lower limit) to 235.55 mg/dL (upper limit); Serum Triglycerides: 32.75 mg/dL to 170.67 mg/dL; LDL Cholesterol: 62.08 mg/dL to 149.35 mg/dL; HDL Cholesterol: 23.59 mg/dL and 61.23 mg/dL These values reflect the range within which 90% of the population in this subgroup is expected to fall. We had collected second set of fasting, 2-hr post breakfast and 2-hr post lunch blood samples (n=312) from healthy individuals of various age groups. Samples were analysed by partitioning and by comparing fasting, 2-hr post breakfast and 2-hr post lunch lipid data. Regarding fasting versus postprandial measurements, Total Cholesterol showed no significant difference, there were Significant mean difference between fasting and post lunch Serum triglyceride in all gender-age groups. HDL-C showed no significant variation with meal timing, whereas LDL-C demonstrated significant changes in both sexes aged 26–50 years. The study underlines the importance of age- and gender-specific reference ranges and shows how graphical and statistical techniques can effectively classify and analyse lipid disorders.
Immunomodulatory activity and phytochemical analysis of selected plants used in folk medicine of palakkad for post natal care
(Government Victoria College Palakkad, University of Calicut, 2026) Jayalekshmi, C V; Suresh, V
The study investigates the immunomodulatory and phytochemical profiling of selected plants used in the folk medicine of Palakkad for postnatal care. The traditional medicinal practices play a vital role in postnatal care of Kerala. Our study mainly focussed on plants used for making vethuvellam, a traditional medicated water for bathing mothers after delivery. The study documented the plants used for bathing mothers and infants after delivery. The medicated bath enhances immunity, reduces inflammations and prevents infections. Despite the traditional significance, scientific validation is lacking in this aspect. Our study aimed to document the plants used for traditional bathing of mother and child in Palakkad district, evaluate the bioactivities of selected plants and analyze the phytochemical profile of selected plants. A survey was conducted on plants used for bathing mother and child in various parts of Palakkad district. 282 informants from the district participated in the survey. 62 plant species used for bathing mother and child after delivery were documented from the survey. The study also reported the various combinations of plants used for making vethuvellam. Quantitative ethnobotanical tools like Relative frequency of citation (RFC), Consensus index (CI) and Use value (UV) were used to express the collected data. Curcuma longa and Artocarpus heterophyllus showed high RFC, CI and UV. Acalypha fruticosa Forssk., Justicia gendarussa Burm. f., Piper longum L. and Vitex altissima L. f. were selected for further studies based on the survey and prior literature. Leaf extracts of these selected plants in hexane, water and isopropyl alcohol were used in the study. The preliminary phytochemical analysis was done using standard qualitative test. Preliminary phytochemical screening confirmed the presence of alkaloids, flavonoids, tannins, phenolics and saponins across the extracts. This research investigated the immunomodulation properties of 4 selected plants using in vitro macrophage activation studies in THP1 cells. All the four plants modulate the immune system via upregulating or down regulating the expression of IL-1β, IFNβ, TNFα, and CCR-5. V. altissima was selected for detailed immunomodulation studies. The hexane (VAH) and isopropyl alcohol (VAI) extract of V. altissima upregulated the gene expression of IL-1β, IFNβ, TNFα, and CCR-5 indicating the immunostimulatory property of both extracts. Our research also studied the antioxidant and antibacterial properties of three different extracts of V. altissima. DPPH assay was used to study the antioxidant activity Our research also studied the antioxidant and antibacterial properties of three different extracts of V. altissima. DPPH assay was used to study the antioxidant activity and agar disc diffusion studied against Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was used to explore the antibacterial activity. The V. altissima isopropyl alcohol (VAI) extract exhibited superior antioxidant and antibacterial activities. This study also analysed Orbitrap high resolution liquid chromatography mass spectrometry (OHR-LCMS) for compound identification from V. altissima hexane, water (VAW) and isopropyl alcohol extracts. 89 compounds were obtained from VAW, 55 compounds were obtained from VAH and 55 compounds were obtained from VAI. Majority of these compounds possessed many bioactivities. Our study also highlighted the anti-inflammatory potential of V. altissima isopropyl alcohol extract using lipopolysaccharide (LPS) stimulated THP1 derived macrophages. The extract significantly downregulated the expression of IL-1β, IFNβ, TNFα, IL-6 and CCR-5 compared to LPS stimulated control group. The V. altissima isopropyl alcohol extract also exhibited antifungal activity against Aspergillus niger studied using food poison technique. The TLC analysis of VAI extract revealed the presence of seven compounds. The antibacterial activity of TLC fractions was also studied against B. subtilis, E. coli, P. aeruginosa and S. aureus. The fractions C5, C6, and C7 showed maximum antibacterial activity against E. coli and B. subtilis. This study validates the importance of vethuvellam in postnatal care of Palakkad district. V. altissima emerges as a leading candidate for drug development due to its immunostimulatory, anti-inflammatory, antibacterial, antioxidant and antifungal activities. The research also supports the folk medicinal use of this plant. The documentation of folk medicinal plants for postnatal care is essential to protect the traditional knowledge.
Integrating taxonomy phylogeny host plant associations and gut microbial diversity in lynx spiders Araneae Oxyopidae of Kerala
(Christ College , Inrinjalakuda, University of Calicut, 2026) Amulya Baji, K; Honey Sebastian; Sudhikumar A V
Lynx spiders (Oxyopidae) are widespread across various ecosystems in Kerala. This family, which does not create webs, comprises fast and visually adept hunters that use speed and precision to ambush their prey, typically found on flowers and leaves. Their distinctive spiny legs and hexagonally arranged eyes enhance their hunting prowess. This study investigates the diversity of Lynx spiders in Kerala. Given the highly cryptic nature of Oxyopids, a more dependable method that integrates classical and molecular taxonomy has been employed instead of traditional techniques. A total of thirty-one Oxyopid species across four genera (Oxyopes, Hamataliwa, Hamadruas, and Peucetia) have been identified in Kerala. Notably, this research introduces eleven new Oxyopes species: O. tigris, O. peetham, O. solea, O. ramulus, O. auris, O. hippocampus, O. circum, O. aquilae, O. kasaragodensis, O. thumboormuzhiensis, and O. patera. In addition, O. striagatus and O. shakilae are recorded for the first time in India. New species identified within the Hamataliwa genus include H. triangulus, H. quadrata, H. sagitta, H. crista, and H. rhombiae. DNA barcoding of the 31 species gives consensus sequences of 19 species only. The adaptability and hunting tactics of Oxyopids make them excellent subjects for evolutionary _and ecological studies. Th;;@\( evolutionary relationship of Oxyopids was determined by constructing phylogenetic trees usj DNA barcodes derived from the mitochondrial Cytochrome C Oxidase subunit I (CO1) marke. Four phylogenetic trees Neighbour Joining, Maximum Parsimony, Bayesian, and Maximum Likelihood - were created to establish more dependable taxonomic placements. As dominant predators of crop pests, Oxyopidae species&;v?romising roles in natural pest control. In this context, the study examined the host plant preferences of Lynx spiders across different ecosystems in Kerala, identificd 88 host plants from 30 families. The Poaceae family showcased the highest species richness and abundance, while Balsaminaceae exhibited the lowest. An observable preference for invasive plants over exotic and native varieties among lynx spiders was noted. Manipulating gut microbes in spiders could enhance Lynx spider populations for natural biocontrol methods, potentially decreasing the reliance on chemical pesticides for pest management. The gut microbial composition in spiders varies based on the ecosystems. The present study compares the gut microbial diversity of O. birmanicus from four different ecosystems, including an urban area, forest, dam side and paddy field and identifies 107 bacterial species, 162 genera, 88 families, 56 orders, and 27 classes belonging to 18 phyla. O. birmanicus from the dam side has higher gut microbial diversity, and the species from the urban area have the lowest. This study involves integrating four aspects in the Lynx spiders, & novel approach from Kerala, and has prospective uses in pest management in the state’s ecosystems.
Broadband spectral analysis and variability of AGNs
(Providence Womens College Calicut, 2026) Akhila K; Jeena K
Active Galactic Nuclei (AGNs) are among the most powerful persistent sources of electromagnetic energy in the Universe, powered by accretion of mass onto supermassive black holes. Studying their broadband spectra and variability pat- terns can provide information on the geometry, physical conditions and energetics of the accretion disk-corona system. This thesis investigates the physical pro- cesses governing AGN mechanism through a combination of broadband spectral modelling and variability informed X-ray analysis using data from AstroSat, NuS- TAR and XMM-Newton. Long term spectral analysis of the Seyfert 1 galaxy, Mrk 279, using multi-epoch data was conducted to examine the evolution of the source’s flux state and the associated variations in individual components. The study revealed significant source variability without consistent correlation between photon index and continuum intensity. Variations in spectral shape fol- lows only the long term flux state variability and not short timescale variabilities. Flux variability without accompanying spectral shape variability can undermine small changes in physical parameters, necessitating variability analyses along with broadband spectroscopy. Incorporating temporal information with spec- tral modelling, a novel method for modelling the energy dependent variability is introduced. The method is demonstrated by applying to an XMM-Newton observation of the NLS1 galaxy, Mrk 335, whose spectrum can be described by (i) a partial covering absorber modifying the primary emission, (ii) a warm and hot coronal model and (iii) gravitationally blurred reflection along with primary emission. The source’s intrinsic variability, quantified through fractional rms variability amplitude can be utilised to break the degeneracy between the spec- tral models. The study presents a technique to estimate fractional rms from the spectral model and identify the model parameters that best recreates the observed variability pattern. Together the studies consider the different com- plementary aspects of AGN behaviour, demonstrating that a multi-domain ap- proach combining long term spectral evolution along with variability-informed modelling provide a powerful tool to understand AGN physics.