Shedding light on the lives of star forming galaxies

This thesis examines two separate aspects related to the evolution of star forming galaxies using spectroscopic and photometric measurements taken from large area sky surveys. The first part of the thesis focuses on the local evolution of star formation rate density, and the second part explores the universality of the stellar initial mass function (IMF). The first part of this thesis is motivated by the published measurements of the low z H luminosity (LH) functions,, that show a large dispersion in the local number density of sources (0.5 1 Mpc-3dex-1), and correspondingly in the SFR density. The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, and different methods of correcting for dust obscuration and AGN contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 SFR H (solar masses per year) 100 with which to robustly measure the evolution of the SFR density in the lowz universe. The large number of high SFR galaxies present in our sample allows an improved measurement of the bright end of the luminosity function, indicating that the decrease in at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the FIR and radio. For GAMA and SDSS we find the rband apparent magnitude limit, combined with the subsequent requirement for H detection leads to an incompleteness due to missing bright H sources with faint rband magnitudes. To correct for this incompleteness, we use the lowest redshift LHabsolute (rband) magnitude and LHstellar mass distributions as a reference to model the higherz bivariate luminosity functions, thereby approximating the contribution from the missing optically faint star forming galaxies to the local star formation rate and stellar mass densities. The second part of this thesis is motivated by the recent extragalactic studies indicating variations in the stellar IMF. The IMF describes the distribution in stellar masses produced from a burst of star formation. For more than fifty years, the implicit assumption underpinning most areas of research involving the IMF has been that it is universal, regardless of time and environment. We measure the highmass IMF slope for a sample of lowtomoderate redshift galaxies from the GAMA survey. The large range in luminosities and galaxy masses of the sample permits the exploration of underlying IMF dependencies. A strong IMFstar formation rate dependency is discovered, which shows that highly star forming galaxies form proportionally more massive stars (they have IMFs with flatter powerlaw slopes) than galaxies with low star formation rates. This has a significant impact on a wide variety of galaxy evolution studies, all of which rely on assumptions about the slope of the IMF. Our result is supported by, and provides an explanation for, the results of numerous recent explorations suggesting a variation of or evolution in the IMF

Characterization of Vrille Function in the Drosophila Circadian Clock

TThe Drosophila circadian clock is comprised of transcriptional feedback loops, which control rhythmic gene expression and are also responsible for daily rhythms in physiology, metabolism and behavior. The core feedback loop, which employs CLOCK-CYCLE (CLK-CYC) activators and PERIOD-TIMELESS (PER-TIM) repressors to drive rhythmic transcription peaking at dusk, is required for circadian timekeeping and overt behavioral rhythms. CLK-CYC also activates an interlocked feedback loop, which uses PAR DOMAIN PROTEIN 1ɛ (PDP1ɛ) activator and VRILLE (VRI) repressor to drive Clk and other rhythmic transcription peaking at dawn. In addition to its role in the clock, vri controls many developmental processes which are essential for early embryonic development, making vri null mutants embryonic lethal. This has hindered the ability to determine the role that vri plays within the circadian clock. The goal of my study is to determine if vri is necessary for circadian time keeping and/or output. To achieve this goal, I first determined which transcripts were important for clock function. I generated an isoform specific vri mutant, which eliminated the expression of mRNAs that were thought to be essential for clock function. It turned out that these mutants are hypomorphic, as residual VRI expression was still observed in the clock cells of these mutants. Further analysis demonstrated that another vri mRNA isoform is expressed rhythmically under the control of the clock. Interestingly, the mutation impacted the abundance of short and long proteins, since the mutated mRNA can produce both VRI protein isoforms using an alternative translation initiation site. Furthermore, the E-boxes that are used by CLK-CYC are important for development, since deletion of these E-boxes leads to embryonic lethality. Then using a conditionally inactivatable transgene to rescue vri developmental lethality, I showed that clock function persists after vri inactivation, but activity rhythms were abolished. The inactivation of vri disrupts multiple output pathways thought to be important for activity rhythms, including Pigment-Dispersing Factor (PDF) accumulation and arborization rhythms in the small ventrolateral neuron (sLNvv) dorsal projection. These results demonstrate that vri acts as a key regulator of clock output, and suggests that the primary function of vri in Drosophila is to drive rhythmic transcription, which is required for overt rhythms

The Fermilab SpinQuest Experiment: Commissioning and plans toward production

E1039/SpinQuest, a transversely-polarized Drell-Yan experiment at Fermilab, plans to use the 120 GeV proton beam and polarized NH3 and ND3 cryogenic targets to study azimuthal asymmetries in dimuon production to extract the magnitude as well as sign of the sea quarks Sivers functions. The SpinQuest spectrometer is optimized to detect oppositely-charged muons with a series of tracking chambers and hodoscope stations. The scope of this manuscript is to highlight the physics goals and the experimental setup with a focus on the ongoing debugging and training of one of the tracking systems, mainly drift chambers, as preparation for the upcoming commissioning and production run-periods. This work is supported in part by the US DOE contract number DE-FG02-07ER41528. Key words: Drell-Yan, Fermilab, SpinQuest, Polarization, Tracking, Drift Chamber

Shedding light on the lives of star forming galaxies

This thesis examines two separate aspects related to the evolution of star forming galaxies using spectroscopic and photometric measurements taken from large area sky surveys. The first part of the thesis focuses on the local evolution of star formation rate density, and the second part explores the universality of the stellar initial mass function (IMF). The first part of this thesis is motivated by the published measurements of the low z H luminosity (LH) functions,, that show a large dispersion in the local number density of sources (0.5 1 Mpc-3dex-1), and correspondingly in the SFR density. The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, and different methods of correcting for dust obscuration and AGN contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 SFR H (solar masses per year) 100 with which to robustly measure the evolution of the SFR density in the lowz universe. The large number of high SFR galaxies present in our sample allows an improved measurement of the bright end of the luminosity function, indicating that the decrease in at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the FIR and radio. For GAMA and SDSS we find the rband apparent magnitude limit, combined with the subsequent requirement for H detection leads to an incompleteness due to missing bright H sources with faint rband magnitudes. To correct for this incompleteness, we use the lowest redshift LHabsolute (rband) magnitude and LHstellar mass distributions as a reference to model the higherz bivariate luminosity functions, thereby approximating the contribution from the missing optically faint star forming galaxies to the local star formation rate and stellar mass densities. The second part of this thesis is motivated by the recent extragalactic studies indicating variations in the stellar IMF. The IMF describes the distribution in stellar masses produced from a burst of star formation. For more than fifty years, the implicit assumption underpinning most areas of research involving the IMF has been that it is universal, regardless of time and environment. We measure the highmass IMF slope for a sample of lowtomoderate redshift galaxies from the GAMA survey. The large range in luminosities and galaxy masses of the sample permits the exploration of underlying IMF dependencies. A strong IMFstar formation rate dependency is discovered, which shows that highly star forming galaxies form proportionally more massive stars (they have IMFs with flatter powerlaw slopes) than galaxies with low star formation rates. This has a significant impact on a wide variety of galaxy evolution studies, all of which rely on assumptions about the slope of the IMF. Our result is supported by, and provides an explanation for, the results of numerous recent explorations suggesting a variation of or evolution in the IMF

Performance of Machine Learning Classification in Mammography Images using BI-RADS

This research aims to investigate the classification accuracy of various state-of-the-art image classification models across different categories of breast ultrasound images, as defined by the Breast Imaging Reporting and Data System (BI-RADS). To achieve this, we have utilized a comprehensively assembled dataset of 2,945 mammographic images sourced from 1,540 patients. In order to conduct a thorough analysis, we employed six advanced classification architectures, including VGG19 \cite{simonyan2014very}, ResNet50 \cite{he2016deep}, GoogleNet \cite{szegedy2015going}, ConvNext \cite{liu2022convnet}, EfficientNet \cite{tan2019efficientnet}, and Vision Transformers (ViT) \cite{dosovitskiy2020image}, instead of traditional machine learning models. We evaluate models in three different settings: full fine-tuning, linear evaluation and training from scratch. Our findings demonstrate the effectiveness and capability of our Computer-Aided Diagnosis (CAD) system, with a remarkable accuracy of 76.39\% and an F1 score of 67.94\% in the full fine-tuning setting. Our findings indicate the potential for enhanced diagnostic accuracy in the field of breast imaging, providing a solid foundation for future endeavors aiming to improve the precision and reliability of CAD systems in medical imaging

Introduction to Computer-Aided Learning

In modern times, technology has taken on a dominant role in many aspects of human life, and computeraided learning (CAL) is an educational tool that makes learning easier. By employing user interface (UI) design it is easy for students to access learning materials and relevant courses. UI design is an important factor for designing useful and usable CAL to appeal to a wide range of users by making the system flexible, attractive, interactive and easy to use

ADOPTION OF SUSTAINABLE REAL ESTATE DEVELOPMENT IN SRI LANKA: A GAP ANALYSIS

The real estate sector in Sri Lanka has been experiencing more remarkable growth during the past decades. The emergence of innovative local and foreign investors, favourable government policies, urbanisation, enhancement of housing requirements and other socioeconomic factors have driven the scope of the real estate sector to a greater extent. The drastic demand for investments and economic policies has transformed traditional real estate values into an innovative range while intersecting globalisation. The vast competition in the market, innovative trends, expansion of infrastructure, direct ownership opportunities, enrichment of living standards and growth of human needs have inspired real estate investors to achieve greater profits. Although such investment processes are empowered by governmental laws, regulations, policies and standards, the present nature of real estate investments exhibits a tendency not to sustain the future needs of Sri Lanka when achieving profits. Moreover, according to the literature and existing case studies, it is evident that investors avoid considering long-term solutions in real estate. Hence, this investigation demonstrates the necessity of adopting sustainable approaches to define a baseline for real estate investors’ financial perspectives within the Sri Lankan context. It examines the nature of practice in real estate to address the necessity of sustainable real estate development in Sri Lanka. The study has adopted a qualitative approach and aimed at obtaining data via secondary sources. The analysis of data was subjected to be undertaken through a content analysis for a better overview. The research findings are significant in assessing investment opportunities, valueadded real estate developments, sustainable necessities, and future trends in real estate development in Sri Lanka. Keywords: Real Estate, Sustainable Real Estate Development, Sri Lanka

An Analysis of the Impact of Financial Literacy on Credit Utilisation Behaviour of the Farmers in Kamburupitiya DS division

Agriculture is the major livelihood of the rural populations in many developing countries, including Sri Lanka. In order to feed the increasing number of mouths, subsistence agriculture is moving towards commercialised agriculture in order to increase production. On that point, agricultural credit plays a vital role in obtaining the mesentery inputs like land, machinery, seeds, fertilisers, pesticides, and labour force. However, as a result of the mismanagement of loan utilisation by farmers due to poor financial literacy, they were not able to get the expected return on agricultural loans. Therefore, this investigation was carried out in the Kambutupitiya DS division in the Matara District to find out the impact of financial literacy on the credit utilisation behaviour of the farmers and to determine the factors affecting their credit utilisation behaviour and financial literacy. The population consisted of 125 borrowers from Govijana Bank, which belongs to the agrarian service department, and 60 farmers were selected using simple random sampling. Data were analysed descriptively and statistically using SPSS. The credit facility was fully utilised only by 25% of the respondents, partially utilised by 35%, and the remaining 40% mis-utilised the loan. The study revealed that socio-demographic characteristics such as age, educational level, income level, loan size, and purpose of the loan do not have any significant influence on the credit utilisation behaviour of the farmers. However, family size has a significant impact on credit utilisation behaviour (P=0.016). Only 17% of the respondents have sound financial literacy. The majority of farmers have a moderate level of financial literacy (65%) and 18% of farmers have a lower level of financial literacy. Educational level (P=0.001) and income level (P=0.012) have a significant influence on financial literacy and age has not significantly impacted the financial literacy level of farmers. In the Sri Lankan context, there are opportunities to do further research at the provincial and national levels. The research suggests that policies should be implemented to incorporate financial knowledge at all levels of the education system. Keywords: Agriculture, Agricultural Loan, Credit Utilisation, Financial Literacy, Govijana Ban

Awareness of Rational Medication Use and Antibiotic Self- Medication Practices among Undergraduate Students in a University in Sri Lanka

Purpose: To evaluate the practice of self-medication and evaluate the knowledge of rational use of antibiotics among undergraduate students of University of Peradeniya, Sri Lanka.Method: A cross-sectional, recall study was conducted among the university student population who practice self-medication in the study location. Stratified, random sampling technique was used to distribute 246 questionnaires in eight faculties of the institution. The response rate was 71%, and 175 completed questionnaires were analyzed to determine significant differences and correlation with different variables.Results: A majority of the study sample were females (54%), aged 23 - 25 years (46.9%). The most frequently used antibiotic was amoxicillin (95.4%). Common cold with fever was the disease condition treated by a large majority (84.9%). Knowledge on dose, frequency, duration and side-effects of antibiotics among students was moderate, with a mean value of 58.3%. There was a significant difference in knowledge on antibiotics between health science and non-health science students although no significant difference was observed in knowledge with respect to gender, academic year and family income.Conclusion: Antibiotic consumption was associated with students’ academic background. This study highlights the need for interventions to assure rational use of antibiotics.Keywords: Antibiotics, Self-medication, Rational use, Undergraduate students, Awarenes