Geogenic Pollution of Groundwater Quality in Gampaha District, Sri Lanka: A Case Study of Groundwater Acidification from Rathupaswala

Over recent decades, Gampaha district, Sri Lanka, has experienced significant urbanisation and industrial growth, increasing groundwater demand due to limited and polluted surface water resources. In 2013, a community uprising in Rathupaswala, a village in Gampaha district, accused a latex glove manufacturing factory of causing groundwater acidity (pH < 4). This study evaluates the spatial and temporal changes in geochemical parameters across three transects in the southern part of Gampaha district to 1) assess the impact of geological formations on groundwater;2) compare temporal variations in groundwater;and 3) explain acidification via a geochemical model. Seventy-two sample locations were tested for pH, electrical conductivity (EC), and anion concentrations (sulphate, nitrate, chloride and fluoride). Depth to the water table and distance from the sea were measured to study variations across sandy, peaty, lateritic, and crystalline aquifers. Results showed pH readings around 7 for sandy and crystalline aquifers, below 7 for peaty aquifers, and below 5 for lateritic aquifers, with significant water table fluctuations near Rathupaswala area. Principal component analysis revealed three principal components (PCs) explaining 86.0% of the variance. PC1 (40.6%) correlated with pH, EC, and sulphate (saltwater intrusion), while PC2 (32.0%) correlated with nitrates and depth to the water table (anthropogenic nutrient pollution). A geochemical transport model indicated a cone of depression recharged by acidic groundwater from peat-soil aquifers, leading to acidic groundwater in Rathupaswala area. Previous attributions of acidic pH to the over-exploitation of groundwater by the latex factory have been reevaluated;the results suggest natural acidification from prolonged water-rock interactions with iron-rich lateritic aquifers. Groundwater pH is influenced by local climate, geology, topography, and drainage systems. It is recommended that similar water-rock interaction conditions may be present throughout the wet zone of Sri Lanka, warranting detailed studies to confirm this hypothesis.

Effects of climate,soil and water source on determining exchangeable copper concentration in lowland paddy fields in Sri Lanka

Copper(Cu)is an essential micronutrient for rice.However,the current status of Cu in Sri Lankan paddy soils is not known.Therefore,the current study was conducted to determine the distribution of exchangeable Cu concentration and examine the interactive effects of the agro-climatic zone(ACZ),soil order,and water source in determining the exchangeable Cu concentration in lowland paddy fields in Sri Lanka.A total of 7,544 soil samples representing six ACZs,six soil orders,and three water sources were collected using a stratified random sampling approach.Soil exchangeable Cu fraction was extracted in 0.01 M CaCl_(2)and measured using Inductively Coupled Plasma Mass Spectrophotometry.Exchangeable Cu concentration was in the range of 0.04−728μg·kg^(−1)with a mean value of 62.4μg·kg^(−1).Only 5%of the soil samples tested had Cu concentration greater than 200μg·kg^(−1)indicating a widespread Cu deficiency in Sri Lankan paddy fields(i.e.critical level causing Cu deficiency;200-300μg·kg^(−1)).Among the climatic zones Wet zone had higher and the Dry zone had lower Cu concentrations.Among the soil orders,histosols had higher and alfisols had lower Cu concentrations.Water sources used for rice cultivation did not determine Cu concentration.Moreover,Cu concentration was positively correlated with soil pH.As most of the soil samples were deficient in soil exchangeable Cu,spatial maps generated in the current work could be used to develop ACZ and soil order-specific agronomic and management strategies to improve soil Cu fertility status.

Relationship of Internet Addiction with Depression, Loneliness and Health Related Lifestyle among University Students

Internet addiction （IA） is a newly emerged clinical disorder and it has negative effects on physical and mental health. University students are the most vulnerable group for IA, The aim of the present study was to determine the relationship of IA with depression, loneliness and health related lifestyle among university students. Cross-sectional survey was conducted by enrolling 175 students of Faculty of Allied Health Sciences, University of Peradeniya. Internet addiction test （IAT） was used to assess the level of IA. Depression, loneliness, and health related lifestyle were assessed using Peradeniya depression scale （PDS）, University of California at Los Angeles （UCLA） loneliness scale and health practice score （HPS） respectively. T-test and ANOVA were conducted to examine the differences; and correlation and regression analyses were used to examine the relationships between variables. Overall, 40.6% of students were placed in IA group. Generally 28.6% of students had mild and 12.0% had moderate addiction. No case of severe IA was seen. There were 20.6% of students in depressive state and 17.1% of students had poor HPS. The average score that the student got from loneliness scale was 23.42. There was a positive significant correlation between IA and both depression and loneliness. Moreover, a negative significant correlation found between IA and health related lifestyle. Male students had higher IA scores than female students. The study results are considered to develop preventive interventions and treatment strategies.

Repeat OGTT at 34 - 36 Weeks to Detect the Late Occurrence of GDM: A Descriptive Cross-Sectional Study Conducted at the Professorial Unit, Teaching Hospital Peradeniya, Sri Lanka

Aim: Evaluation of the occurrence of glucose intolerance after 34 - 36 weeks in pregnant mothers attending the Teaching Hospital, Peradeniya. Materials & Method: This is a descriptive cross-sectional study carried out from October 2017 to March 2018 among 183 pregnant mothers attending antenatal clinic at Teaching Hospital Peradeniya. After informed consent a repeat Oral Glucose Tolerance Test (OGTT) was done among the pregnant mothers, at period of amenorrhoea of 34 - 36 weeks, whose initial OGTT values were normal. Gestational diabetes was diagnosed according to the NICE guideline cut off values and the percentage of late occurrence of Gestational diabetes (GDM) was analyzed. Results: Mean age of the population was 29.1 years and the age range in this group was 18 to 45 years and the majority (73.9%) of women were primipara. There were 3.3% of teenage pregnancies and 14% of mothers were over 35 years. Majority (59.7%) of mothers underwent repeat OGTT test at 34 weeks of gestation and the rest (40.3%) underwent test between 34 to 36 weeks of gestation. Although the mean BMI was 23.74, 9.7% of mothers were obese (>30 kg/m2), 30.3% of mothers were pre-obese (25.0 - 29.9 kg/m2). 8.2% of mothers were diagnosed with Gestational diabetes at 34 - 36 weeks whose initial OGTT values were normal. Conclusion: In view of reducing feto-maternal morbidity and mortality, considering a repeat OGTT at a later gestation (34 - 36 weeks of gestation) should be considered in mothers, whose initial OGTT values are normal as Sri Lanka is a high risk country for GDM. Clinical Significance: The study may play an important role in guideline alteration process and screening for gestational diabetes in Sri Lankan set-up.

A Comparison of One Hour versus Two-Hour Postprandial Glycemic Control during Pregnancy: A Prospective Cohort Study Carried out at Antenatal Ward Teaching Hospital Peradeniya, Sri Lanka

Background It is well known that both pre-excising and gestational diabetes mellitus in pregnancy is associated with multiple maternal and fetal complications. There are various guidelines developed to reduce these complications, yet there is no universal agreement regarding the ideal management. For those with pre-exciting or gestational diabetes mellitus, the control of blood sugar is assessed either with 1st-hour post-prandial blood sugar values or with the 2nd-hour post-prandial blood sugar values. Objective To compare the long-term blood glucose control (HbA1c values) of pregnant women by utilizing results of 1-hour postprandial blood sugar values against 2-hour post-prandial blood sugar values, in the antenatal ward at the professorial unit, Teaching Hospital Peradeniya. Materials and Methods A prospective cohort study was carried out among 138 pregnant women with diabetes mellitus, who were managed in two different clinics at the professorial unit, Teaching Hospital Peradeniya. The blood glucose control in group 1 (n = 69) was assessed and optimized with 1st-hour postprandial blood sugar values and group 2 (n = 69) was evaluated with 2nd-hour postprandial values throughout the pregnancies. Following delivery, all subjects were reassessed with blood HbA1c and analyzed with the independent t-test. Feto-maternal complications were analyzed and evaluated using descriptive statistics and Chi-Square tests. Results Of the subjects, 97.1% were diagnosed with gestational diabetes mellitus. The mean value of HbA1c for group 1, managed with 1st-hour blood glucose values was 5.73 and 6.04 (p = 0.02) respectively for group 2. Fetal macrosomia was also significantly (p < 0.01) low in the 1-hour blood sugar control group. Conclusion Long-term control of blood sugar was significantly superior among the subjects managed with 1st-hour postprandial blood sugars with a statistically significant reduction in foetal macrosomia.

Examine the Reliability of Econometrics Software: An Empirical Comparison of Time Series Modelling

Researchers must understand that naively relying on the reliability of statistical software packages may result in suboptimal, biased, or erroneous results, which affects applied economic theory and the conclusions and policy recommendations drawn from it. To create confidence in a result, several software packages should be applied to the same estimation problem. This study examines the results of three software packages (EViews, R, and Stata) in the analysis of time-series econometric data. The time-series data analysis which presents the determinants of macroeconomic growth of Sri Lanka from 1978 to 2020 has been used. The study focuses on testing for stationarity, cointegration, and significant relationships among the variables. The Augmented Dickey-Fuller and Phillips Perron tests were employed in this study to test for stationarity, while the Johansen cointegration test was utilized to test for cointegration. The study employs the vector error correction model to assess the short-run and long-term dynamics of the variables in an attempt to determine the relationship between them. Finally, the Granger Causality test is employed in order to examine the linear causation between the concerned variables. The study revealed that the results produced by three software packages for the same dataset and the same lag order vary significantly. This implies that time series econometrics results are sensitive to the software that is used by the researchers while providing different policy implications even for the same dataset. The present study highlights the necessity of further analysis to investigate the impact of software packages in time series analysis of economic scenarios.

Microplastic pollution in the Indian Ocean: Passageways and the contamination of the open ocean and its marine environment

Microplastics(MPs)are man-made litter receiving current conversation of interest as a silent pollutant to Earth.Its impact is high on the coastal waters,sediment and organisms of the marine environment.It is a pertinent requirement to investigate the microplastic MP contamination in the marine environment of the Asian region aiming at the world’s 3rd largest ocean,the Indian Ocean.Among the different samples,Indian Ocean water and deep-sea sediment samples have mostly been investigated covering the Southwestern Sumatran region(Eastern Indian Ocean)which is a well-known domestic and industrial shipping route.Majority of the tested samples were in the form of granules,fibers and fragments of 100-500μm and 38-6,330μm in size range respectively in deep-sea sediment samples and in ocean water samples.Further,the prominent MPs types were PVC(polyvinyl chloride),PP(polypropylene)synthetic micro debris,Poly methyl methacrylate PMMA plastic micro debris,PTFE(polytetrafluoroethylene),and nylon.Floating plastic debris has also been found on surface ocean waters in the Eastern Indian Oceanic region as an emergent floating litter.Its size range and the percentage abundance were documented as 0.5-5 mm and 50%respectively.Moreover,the Western Indian Oceanic region has reported the highest percentage abundance of MPs in ocean waters(10.48%).These MPs were assumed to derive from fiber or fishing line material,regional fishery activities and the sewage disposal debris of tourist-based coastline anthropogenic activities.The polymer-specific sources that release this potential pollutant were not yet accurately discovered.This review article elaborates on the topic by reviewing the MPs’pervasiveness,identifying different passageways and sources of discharging MPs to the Indian Ocean and finally the ecological and socio economic risks of the matter.Thus,it may highlight the knowledge gaps which more research studies should be focused on.

A Study on Risk Factors for Venous Thromboembolism and the Requirement of Thromboprophylaxis in Pregnancy and Postpartum Period in a Tertiary Care Centre in South Asian Country: A Cross Sectional Study

Introduction: Thrombosis is a major cause of maternal death worldwide. During pregnancy, the risk of venous thromboembolism (VTE) increases fourfold to five-fold and contributes towards maternal morbidity and mortality. Sri Lanka does not have a proper assessment tool to detect and manage it in the antenatal care. Objectives: To identify risks factors for VTE among pregnant mothers, postpartum mothers according to RCOG (Royal College of Obstetricians) risk categorization and to assess the requirement of thromboprophylaxis. Method: A cross sectional study was conducted at the antenatal clinics and obstetrics and gynaecology wards (ward 2, 5, 8) of De Soysa Hospital for Women in 2021. Obstetric thromboprophylaxis risk assessment tool recommended by the RCOG was used for the risk assessment of pregnant mothers during the antenatal and postpartum period. Results: In antenatal period, obesity (BMI > 35), age more than 35 years and parity more than 3 were the commonest risk factors. Out of 404 mothers, 67.33% did not have any risk factors. Among others, 18.56%, 0.40%, 2.72%, 0.99% had a score of 1, 2, 3 and 4 respectively. Patients with intermediate (0.99%) and high risk (2.72%) were commenced on thromboprophylaxis from 28 weeks. The low-risk category was not started on any treatment (28.96%, n = 97). Approximately 96% of mothers did not require any thromboprophylaxis during antenatal period. Another 404 postnatal mothers were recruited for the study group. Elective caesarean section and caesarean section during labour were the main risks identified other than pre-existing antenatal risks. 39.95 % of mothers did not have any risk factors and 37.22% of mothers had a score of 1. Conclusions: VTE risk assessment tool can be implemented at national level to detect patients at risk of VTE and improve maternal care.

Old-growth mixed dipterocarp forests show variable losses and gains in aboveground biomass and standing carbon over forty years

Background:No studies have documented long-term trends in aboveground biomass(AGB)for mixed-dipterocarp forests(MDF),the dominant rain forest type in tropical wet equatorial Asia.In our study,we sought to document such trends over forty years across three sites representing lowland to lower montane elevations.Methods:To do this,we established fifty 100 m×25 m plots in 1978 across three sites sampled along an elevation gradient,identified as mature old-growth forest.We measured trees for diameter at breast height that we identified to species and tagged.We took wood samples to calculate species wood-specific gravity.We re-measured plots in 1998 and again in 2018.Results:We show standing AGB for all sites combined to be 517.52 Mg·ha^(-1)in 1978,but this declined by 17%over 40 years to 430.11 Mg·ha^(-1).No differences exist among sites in AGB primarily because of considerable within site variation;but interactions of time with site show declines across sites were not uniform,one remained about the same.Relatively few species represented a high proportion of the AGB with the top five species comprising between 34%and 65%,depending upon site and year sampled.One species,Mesua nagassarium,represented a disproportionately large amount of AGB and decline over time,particularly at the low elevation site.Conclusions:Our results are directly relevant to estimating AGB and standing carbon sequestered in MDF.Our study is the first to demonstrate varying but overall,declining trends in amounts of AGB among forests making predictions of biomass and standing carbon in MDF difficult over wide regions.

Magnesium oxide(MgO)nanoadsorbents in wastewater treatment:A comprehensive review

Wastewater contamination by heavy metals and synthetic dyes presents a significant environmental challenge,necessitating effective and sustainable separation techniques.This review article provides a detailed examination of magnesium oxide(MgO)nanoparticles as an innovative nanoadsorbent for wastewater treatment,with a specific focus on heavy metal and dye removal.The review comprehensively explores various aspects of MgO nanoparticles,including their structural characteristics and synthesis techniques.The article delves into the morphology and crystallographic arrangement of MgO nanoparticles,offering insights into their structural attributes.Given the complexity of adsorption processes,the review identifies and analyzes parameters influencing the adsorption efficiency of MgO nanoparticles,such as temperature,pH,contact time,initial concentration,and co-existing ions.The interplay between these parameters and the adsorption capability of MgO nanoparticles emphasizes the importance of optimizing operational conditions.Furthermore,the review assesses various synthesis methods for MgO nanoparticles,including sol-gel,hydrothermal,precipitation,green synthesis,solvothermal,and template-assisted techniques.It discusses the advantages,limitations,and resulting nanoparticle characteristics of each method,enabling readers to grasp the implications of synthesis processes on adsorption efficiency.This comprehensive review consolidates current insights into the effectiveness of MgO nanoparticles as a potent nanoadsorbent for removing heavy metals and dyes from wastewater covering a wide spectrum of aspects related to MgO nanoparticles.Moreover,there is a need to investigate the use of MgO in the treatment of actual wastewater or river water,in order to leverage its cost-effectiveness and high efficiency for practical water treatment applications in real-time.

New constraints on the P-T path of HT/UHT metapelites from the Highland Complex of Sri Lanka

We report here rare evidence for the early prograde P-Tevolution of garnet-sillimanite-graphite gneiss(khondalite)from the central Highland Complex,Sri Lanka.Four types of garnet porphyroblasts(Grt_1,Grt_2,Grt_3 and Grt_4)are observed in the rock with specific types of inclusion features.Only Grt_3 shows evidence for non-coaxial strain.Combining the information shows a sequence of main inclusion phases,from old to young:oriented quartz inclusions at core,staurolite and prismatic sillimanite at mantle,kyanite and kyanite pseudomorph,and biotite at rim in Grt_1;fibrolitic sillimanite pseudomorphing kyanite±corundum,kyanite,and spinel+sillimanite after garnet+corundum in Grt_2;biotite,sillimanite,quartz±spinel in Grt_3;and ilmenite,rulite,quartz and sillimanite in Grt_4.The pre-melting,original rock composition was calculated through stepwise re-integration of melt into the residual,XRF based composition,allowing the early prograde metamorphic evolution to be deduced from petrographical observations and pseudosections.The earliest recognizable stage occurred in the sillimanite field at around 575℃ at 4.5 kbar.Subsequent collision associated with Gondwana amalgamation led to crustal thickening along a P-T trajectory with an average dP/dT of ~30 bar/℃ in the kyanite field,up to ~660℃ at 6.5 kbar,before crossing the wet-solidus at around 675 ℃ at 7.5 kbar.The highest pressure occurred at P > 10 kbar and T around 780℃ before prograde decompression associated with further heating.At 825℃ and 10.5 kbar,the rock re-entered into the sillimanite field.The temperature peaked at 900℃ at ca.9-9.5 kbar.Subsequent near-isobaric cooling led to the growth of Grt_4 and rutile at T ~880℃.Local pyrophyllite rims around sillimanite suggest a late stage of rehydration at T<400℃,which probably occurred after uplift to upper crustal levels.U-Pb dating of zircons by LAICPMS of the khondalite yielded two concordant ^(206)Pb/^(238)U age groups with mean values of 542±2 Ma(MSWD=0.24,Th/U=0.01-0.03)and 514±3 Ma(MSWD=0.50,Th/U=0.01-0.05)interpreted as peak metamorphism of the khondalite and subsequent melt crystallization during cooling.

Serum TC/HDL-C,TG/HDL-C and LDL-C/HDL-C in predicting the risk of myocardial infarction in normolipidaemic patients in South Asia:A case-control study

Dyslipidemia the major cause of atherosclerosis are suggested to act synergistically with non-lipid risk factors to increase atherogenesis.Low-density lipoprotein cholesterol(LDL-C) is the main therapeutic target in the prevention of CVD.Increased triglycerides(TG) and decreased high-density lipoprotein(LDL-C) are considered to be a major risk factor for the development of insulin resistant and metabolic syndrome.Although the TG/ HDL-C ratio has been used in recent studies as a clinical indicator for insulin resistance,results were inconsistent. The TG/HDL-C ratio is also widely used to assess the lipid atherogenesis.How ever the utility of this rate for predicting coronary heart disease(CHD) risk is not clear.We encountered myocardial infarct patients with normal serum lipid concentration so this study was undertaken to evaluate the usefulness of these lipid ratios in predicting CHD risk in normolipidemic AMI patients and to compare the results with healthy subjects.The aim of the present study was to evaluate serum TC/HDL-C,TG/HDL-C and LDL-C/HDL-C in myocardial infarct subjects with normal lipid profile.To study this,lipid profile was determined in 165 normolipidemic acute myocardial infarction patients and 165 age/sex-matched controls.Total cholesterol,triglycerides,and HDL-cholesterol were analyzed enzymatically using kits obtained from Randox Laboratories Limited,Crumlin,UK. Plasma LDL-cholesterol was determined from the values of total cholesterol and HDL- cholesterol using the friedwalds formula.The values were expressed as means±standard deviation(SD) and data from patients and controls was compared using students t-test.The results and conclusion of the study were:Total cholesterol, TC:HDL-C ratio,triglycerides,LDL-cholesterol,LDL:HDL-C ratio were higher in MI patients(p【0. 001).HDL-C concentration was significantly lower in MI patients than controls(p【0.001).Higher ratio of TC/HDL-C,TG/HDL-C and LDL-C/HDL-C was observed in AMI patients compared to controls.

Value Addition to Waste Material Supported by Removal of Available Phosphate from Simulated Brackish Water—A Low Cost Approach

Phosphorus is one of the major nutrients that have been identified as a limited resource that would end up earlier than predicted at the rate of current consumption. Therefore, attempts to recover phosphorus from waste and its subsequent use are a concern of current researchers. Nevertheless, recovery of nutrients from wastewater is cumbersome because nutrients such as phosphates () and nitrates () prefer to remain in aqueous phase rather than being adsorbed on solid matrixes. Investigation of adsorption of available - P from simulated brackish water, on granulated solid waste material, prepared by crushed autoclaved aerated concrete (CAAC), and subsequent use of the material as phosphate fertilizer would be the focus of this research. Treatment of nutrient-rich brackish water is important because such water is discharged in huge volume at the time of harvesting of shrimp aquaculture ponds. Experiments conducted in simulated brackish water confirmed non-linear adsorption association with changing distribution coefficient (KD) which attributed the maximum removal of about 98% - P from 100 mgdm-3solution at its value of 40. The non-linear adsorption supported by both the Langumuir and the Freundlich isotherm models simultaneously satisfied monolayer adsorption and multilayer adsorption depicted by the regression coefficients of greater than .99 by the linearized forms of the isotherm models. Moreover, promising phosphate uptakes characteristics are exhibited by the adsorbent at the process of repetitive adsorption which resulted in 12 g/kg uptake of phosphate at 81% efficiency. The adsorbent seems to be used as a slow-released phosphorus fertilizer at the end of its life as an adsorbent.

Characterization and Selection of Phosphorus Deficiency Tolerant Rice Genotypes in Sri Lanka

Phosphorus(P) deficiency in soil is a major constrain for rice production. An important set of rice genotypes(landraces, old improved and new improved varieties) were screened for P deficiency tolerance in two major cropping seasons of Sri Lanka, in 2012. The Ultisol soil, which was collected from a plot cultivated with rice without fertilizer application for past 40 years(P_0) at the Rice Research and Development Institute(RRDI), Bathalagoda, Sri Lanka, was used as the potting medium for greenhouse trials. Two field trials were conducted in the same plots at RRDI. Both P_0 and P_(30)(30 mg/kg P_2O_5) conditions were used in the two greenhouse trials. At the early vegetative(three weeks after transplanting), late vegetative(six weeks after transplanting) and flowering stages, plant height and number of tillers per plant were recorded. At the flowering stage, shoots were harvested and shoot dry weight, shoot P concentration, shoot P uptake and P utilization efficiency were measured. All data were statistically analyzed using analysis of variance, regression and cluster procedures. The measured parameters were significantly different between P_0 and P_(30) conditions(P < 0.05). Higher shoot dry weight was reported by the rice genotypes H4 and Marss under P_0 conditions. The regression analysis between shoot dry weight and P utilization efficiency revealed that the studied rice genotypes could be categorized to three P deficiency tolerance classes. A total of 13 genotypes could be considered as highly tolerant and 4 genotypes as sensitive for P deficiency. These results could be used to select parental genotypes for breeding and genetic studies and also to select interesting varieties or landraces for organic rice production.

Distinct metamorphic evolution of alternating silica-saturated and silica-deficient microdomains within garnet in ultrahigh-temperature granulites: An example from Sri Lanka

Here we report the occurrence of garnet porphyroblasts that have overgrown alternating silica-saturated and silica deficient microdomains via different mineral reactions. The samples were collected from ultrahigh-temperature(UHT) metapelites in the Highland Complex, Sri Lanka. In some of the metapelites, garnet crystals have cores formed via a dehydration reaction, which had taken place at silicasaturated microdomains and mantle to rim areas formed via a dehydration reaction at silica-deficient microdomains. In contrast, some other garnets in the same rock cores had formed via a dehydration reaction which occurred at silica-deficient microdomains while mantle to rim areas formed via a dehydration reaction at silica-saturated microdomains. Based on the textural observations, we conclude that the studied garnets have grown across different effective bulk compositional microdomains during the prograde evolution. These microdomains could represent heterogeneous compositional layers(paleobedding/laminations) in the precursor sediments or differentiated crenulation cleavages that existed during prograde metamorphism. UHT metamorphism associated with strong ductile deformation, metamorphic differentiation and crystallization of locally produced melt may have obliterated the evidence for such microdomains in the matrix. The lack of significant compositional zoning in garnet probably due to self-diffusion during UHT metamorphism had left mineral inclusions as the sole evidence for earlier microdomains with contrasting chemistry.

Manifestations and outcomes of leptospirosis during local outbreaks in high endemic districts of Sri Lanka: A retrospective multi-center study

Objective:To determine the clinical presentations and disease outcomes of suspected and confirmed cases of leptospirosis from 3 high endemic districts of Sri Lanka,during outbreaks reported between 2013 and 2017.Methods:The retrospective multi-center study was carried out during 2013-2017 in 5 selected hospitals representing 3 high endemic districts in Sri Lanka.Clinically suspected leptospirosis patients were recruited according to the Communicable Disease Epidemiology Profile Sri Lanka,WHO.Leptospirosis was confirmed by either single microscopic agglutination test titre 1:400 or by positive polymerase chain reaction(PCR)test result.Results:Out of 372 clinically suspected cases,29.00%were confirmed as leptospirosis cases by either microscopic agglutination test(50.00%)or positive polymerase chain reaction(52.77%)and 12.90%were presumptively identified as leptospirosis.Clinical symptoms(headache,vomiting,jaundice and dyspnoea)and variations in haematological parameters(haemoglobin,platelet count)and biochemical parameters(serum creatinine,serum urea,serum bilirubin and C-reactive protein)were associated with confirmed leptospirosis(P<0.05).Acute kidney injury,meningitis,myocarditis,pulmonary haemorrhage and acute liver failure was seen among 21.30%,12.04%,6.48%,6.48%,5.56%,respectively with 4.63%fatality among the leptospirosis confirmed patients.The sensitivity,specificity,positive predictive value and negative predictive value of the case definition of Ministry of Health,Sri Lanka were 96.29%,9.09%,31.13%and 85.71%,respectively,when benchmarked against either positive polymerase chain reaction or microscopic agglutination test as the gold standard.Conclusions:Acute kidney injury is the predominant complication observed among the leptospirosis confirmed patients.However,pulmonary haemorrhage is predominantly associated with mortality.The case definition of Ministry of Health,Sri Lanka is found to have higher sensitivity and enabled the screening of all probable cases of leptospirosis.

Improvement of the Preliminary Test Estimator When Stochastic Restrictions are Available in Linear Regression Model

Ridge type estimators are used to estimate regression parameters in a multiple linear regression model when multicolinearity exists among predictor variables. When different estimators are available, preliminary test estimation procedure is adopted to select a suitable estimator. In this paper, two ridge estimators, the Stochastic Restricted Liu Estimator and Liu Estimator are combined to define a new preliminary test estimator, namely the Preliminary Test Stochastic Restricted Liu Estimator (PTSRLE). The stochastic properties of the proposed estimator are derived, and the performance of PTSRLE is compared with SRLE in the sense of mean square error matrix (MSEM) and scalar mean square error (SMSE) for the two cases in which the stochastic restrictions are correct and not correct. Moreover the SMSE of PTSRLE based on Wald (WA), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests are derived, and the performance of PTSRLE is compared using WA, LR and LM tests as a function of the shrinkage parameter d with respect to the SMSE. Finally a numerical example is given to illustrate some of the theoretical findings.

Performance of Existing Biased Estimators and the Respective Predictors in a Misspecified Linear Regression Model

In this paper, the performance of existing biased estimators (Ridge Estimator (RE), Almost Unbiased Ridge Estimator (AURE), Liu Estimator (LE), Almost Unbiased Liu Estimator (AULE), Principal Component Regression Estimator (PCRE), r-k class estimator and r-d class estimator) and the respective predictors were considered in a misspecified linear regression model when there exists multicollinearity among explanatory variables. A generalized form was used to compare these estimators and predictors in the mean square error sense. Further, theoretical findings were established using mean square error matrix and scalar mean square error. Finally, a numerical example and a Monte Carlo simulation study were done to illustrate the theoretical findings. The simulation study revealed that LE and RE outperform the other estimators when weak multicollinearity exists, and RE, r-k class and r-d class estimators outperform the other estimators when moderated and high multicollinearity exist for certain values of shrinkage parameters, respectively. The predictors based on the LE and RE are always superior to the other predictors for certain values of shrinkage parameters.

Feasible Method to Assess the Performance of a Lung Cancer CT Screening CAD System in Clinical Practice: Dependence on Nodule Size and Density

Detection of small pulmonary nodules is the goal of lung cancer screening. Computer-aided detection (CAD) systems are recommended to use in lung cancer computed tomography (CT) screening to increase the accuracy of nodule detection. Size and density of lung nodules are primary factors in determining the risk of malignancy. Therefore, purpose of this study is to apply computer-simulated virtual nodules based on the point spread function (PSF) measured in same scanner (maintaining spatial resolution condition) to assess the CAD system performance dependence on nodule size and density. Virtual nodules with density differences between lung background and nodule density (ΔCT) values (200, 300 and 400 HU) and different sizes (4 to 8 mm) were generated and fused on clinical images. CAD detection was performed and free-response receiver operating characteristic (FROC) curves were obtained. Results show that both density and size of virtual nodules can affect detection efficiency. Detailed results are possible to use for quantitative analysis of a CAD system performance. This study suggests that PSF-based virtual nodules could be effectively used to assess the lung cancer CT screening CAD system performance dependence on nodule size and density.

Control of a 6DOF Mobile Manipulator with Object Detection and Tracking Using Stereo Vision

A supportive mobile robot for assisting the elderly is an emerging requirement mainly in countries like Japan where population ageing become relevant in near future.Falls related injuries are considered as a critical issue when taking into account the physical health of older people.A personal assistive robot with the capability of picking up and carrying objects for long/short distances can be used to overcome or lessen this problem.Here,we design and introduce a 3 D dynamic simulation of such an assistive robot to perform pick and place of objects through visual recognition.The robot consists of two major components;a robotic arm or manipulator to do the pick and place,and an omnidirectional wheeled robotic platform to support mobility.Both components are designed and operated according to their kinematics and dynamics and the controllers are integrated for the combined performance.The objective was to improve the accuracy of the robot at a considerably high speed.Designed mobile manipulator has been successfully tested and simulated with a stereo vision system to perform object recognition and tracking in a virtual environment resembling aroom of an elderly care.The tracking accuracy of the mobile manipulator at an average speed of 0.5 m/s is 90%and is well suited for the proposed application.