Analysis of experimental designs with unequal group variances.

This thesis deals with weighted (generalised) least squares estimation and analysis for some common experimental designs with the error variance heteroscedastic with respect to the levels of one factor, namely, the treatments or (for split-plot designs) sub-plot treatments. The simple regression model with error variance heteroscedastic with respect to the values of the independent variable, is also considered briefly. The observations in any of the analyses considered are grouped in such a way that the error variance is constant within groups but varies from group to group. On the assumption that the group variances are known, the weighted least squares estimators of the linear parameters and the corresponding analysis (Aitken, 1934-35; Plackett, I960, pp. 47-49) are provided for each design or model. An expression for joint confidence intervals of parametric contrasts for the heteroscedastic models is also obtained. The estimators of the linear parameters and other statistics usually involve actual weights, the reciprocals of the group variances. The actual weights are not usually known. The estimators of the group variances are therefore derived for each design or model. for some designs, the minimum norm quadratic unbiased estimators (Rao, 1970; 1973, pp. 303-305) of group variances are independently distributed as multiples of x2. For other designs, almost unbiased estimators (Horn et al., 1975) of group variances have negligible bias and are approximately independently distri-buted as multiples of x2 Reciprocals of these estimators are used as the estimated weights. The weighted least squares estimators of the linear parameters or variance components and other statistics including test-statistics using estimated weights, are generally biased. It is shown in the thesis how a major part of the bias can be removed; the procedure stems from a theorem due to Meier (1953). The estimators and other statistics using estimated weights are adjusted accordingly. A modified form of this theorem is also proved for correlated estimators of the group variances. A small Monte Carlo study conducted for completely randomised designs showed that the performances of the adjusted statistics are more or less satisfactory. The designs and models covered in this thesis are: completely randomised designs, the general two-way model with proportional cell frequencies, general block designs, randomised complete block designs, latin square designs, split-plot designs with two treatment factors and the linear regression model. For the first three designs, both the fixed-effects models and random or mixed models are considered whereas only the fixed-effects models are dealt with for the remaining three designs

In vitro clonal propagation of locally cultivated pink colour Gladiolus var. Neelima through Cormel-sprout culture

Micropropagation provides an economic advantage for the propagation of a particular crop like gladiolus, a beautiful flowering plant which emits expression of love. Propagation by conventional method is a slow process and pathogen keep on accumulation generation after generation which reduces yield and quality of flower and also generates insufficient propagules. An efficient propagation system could overcome those variabilities and meet the increasing demand of propagules production for the growing of gladiolus in the country while it is an exporting plant in Bangladesh. Moreover, establishment of a plant regeneration system through direct organogenesis or via callus is also a prerequisite to further in vitro genetic manipulation of the cultivar. Demand for disease free planting materials is increasing day by day and crop like vegetatively propagated plant is an appropriate means to generate propagules through in vitro techniques. Production of sufficient numbers of plants of a unique genotype is possible using in vitro culture system. In this study, the effect of various concentrations and combinations of plant growth regulators for in vitro regeneration of gladiolus was described using cormel-sprout as explants. However, an efficient in vitro plant regeneration protocol in locally cultivated pink colour Gladiolus var. Neelima was established on MS media with various hormonal supplements using cormel-sprout as explants. Ninety (90) percent of the explants responded for shooting on 0.5 mg/L BA + 0.5 mg/L Kin within the culture initiation period of 90 days. The average number of shoot per explants was 8 ±1.20 and the average shoot length of 12.40 ±2.15 cm were observed in this medium. Shoots are rooted well when they were excised individually and implanted on half strength of MS medium supplemented with 1.0 mg/l IBA, in which 90% of the shoot induced roots. The average number of root per shoot was 10 ± 1.20 and the average root length of 8.50 ± 1.25 cm were observed in this medium after culture of 30 days. Eighty (80) percent of the in vitro raised plantlets were survived in the natural environment

Seasonal and Altitudinal Prevalence of Fascioliasis in Buffalo in Eastern Nepal

Buffalo is the most important livestock commodities for milk, meat production and several other multipurpose uses distributed densely from southern tarai to northern mid-hills in Nepal. Among several internal parasitic diseases fascioliasis is highly economic one caused by Fasciola in buffaloes. However, there are only few studies carried on prevalence of fascioliasis emphasizing buffaloes in relation to seasonal (summer and rainy, and winter) and altitudinal variations. Therefore, we examined prevalence of fascioliasis seasonally and vertically. For the purpose, we selected two districts of eastern Nepal and sampled from low altitude area known as Madhesha ranging from 175-200, Dhankuta from 800-1200 m, and Murtidhunga from 1800-2200 m elevation from the sea level, representing tarai, mid hills and high hills, respectively. Altogether from February 2013 to January 2014 at every two months interval we collected 798 fecal samples from buffaloes; 282 from Murtidhunga, 239 from Dhankuta and 277 from Madhesha. The samples were examined microscopically for the presence of Fasciola eggs using sedimentation technique. Results showed that overall prevalence of fascioliasis in buffaloes was 39.9% (319/798), ranging highest 42.6%in Madhesha followed by 39.7% in Murtidhunga and 37.2% in Dhankuta, respectively. The prevalence of fascioliasis was found to be significantly (p <0.05) high in winter (44.9%) comparing to rainy season (34.4%). The prevalence of fascioliasis in buffaloes was relatively higher in low altitude than high altitude, although it was not statistically significant (p <0.05). In our findings the female buffaloes showed higher prevalence for fascioliasis than in male. Since the fascioliasis in buffaloes is highly endemic, thus strategic deworming in high risk period is recommended along with measure to prevent pasture contamination with buffalo feces

A blind hierarchical coherent search for gravitational-wave signals from coalescing compact binaries in a network of interferometric detectors

We describe a hierarchical data analysis pipeline for coherently searching for gravitational wave (GW) signals from non-spinning compact binary coalescences (CBCs) in the data of multiple earth-based detectors. It assumes no prior information on the sky position of the source or the time of occurrence of its transient signals and, hence, is termed "blind". The pipeline computes the coherent network search statistic that is optimal in stationary, Gaussian noise, and allows for the computation of a suite of alternative statistics and signal-based discriminators that can improve its performance in real data. Unlike the coincident multi-detector search statistics employed so far, the coherent statistics are different in the sense that they check for the consistency of the signal amplitudes and phases in the different detectors with their different orientations and with the signal arrival times in them. The first stage of the hierarchical pipeline constructs coincidences of triggers from the multiple interferometers, by requiring their proximity in time and component masses. The second stage follows up on these coincident triggers by computing the coherent statistics. The performance of the hierarchical coherent pipeline on Gaussian data is shown to be better than the pipeline with just the first (coincidence) stage.Comment: 12 pages, 3 figures, accepted for publication in Classical and Quantum Gravit

SCREENING OF SOME RESTORER AND MAINTAINER HYBRID RICE LINES AGAINST SHEATH BLIGHT (Rhizoctonia solani)

An experiment was conducted at the field laboratory of Genetics and Plant Breeding Department, BAU, Mymensingh during July to December, 2000. Forty-four test entries of parental lines of rice with one susceptible (BR 11) and one resistant check (BRRI dhan 29) were screened against sheath blight (Rhizoctonia solani) at maximum tillering and flowering stage in the field. The pathogenicity test was studied in the laboratory. Ten lines were resistant, 31 were moderately resistant and 3 showed moderately susceptible reaction at maximum tillering stage. At flowering stage only 2 lines were resistant, 24 were moderately resistant and 18 lines were moderately susceptible

Checklist of fish species in the Shari-Goyain river, Bangladesh: Threats and conservation measures

The study was conducted from September 2017 to August 2018 to investigate the fish diversity status of the Shari-Goyain river, in the northeastern part of Bangladesh. A total of 66 fish species belong to 9 orders and 27 families were identified. Among these, almost 80% of the total fish population was from the orders, Siluriformes, Cypriniformes, and Perciformes. Fishes from the family Cyprinidae (22.71%) were found to be most abundant. Among 14 common groups of fishes identified, the highest contribution (28.79%) was from the catfishes. Ten vulnerable, eight endangered, and one critically endangered fish species were recorded. Alarmingly, based on their availability, 25 % and 18 % of the entire fish community were found to be rare and very rare, respectively. The present study suggests various conservation initiatives entailing the establishment of the fish sanctuary, ranching of threatened fish species, strict enactment of fishing laws and community-based fisheries management

Checklist of fish species in the Shari-Goyain river, Bangladesh: Threats and conservation measures

148-155The study was conducted from September 2017 to August 2018 to investigate the fish diversity status of the Shari-Goyain river, in the northeastern part of Bangladesh. A total of 66 fish species belong to 9 orders and 27 families were identified. Among these, almost 80% of the total fish population was from the orders, Siluriformes, Cypriniformes, and Perciformes. Fishes from the family Cyprinidae (22.71%) were found to be most abundant. Among 14 common groups of fishes identified, the highest contribution (28.79%) was from the catfishes. Ten vulnerable, eight endangered, and one critically endangered fish species were recorded. Alarmingly, based on their availability, 25 % and 18 % of the entire fish community were found to be rare and very rare, respectively. The present study suggests various conservation initiatives entailing the establishment of the fish sanctuary, ranching of threatened fish species, strict enactment of fishing laws and community-based fisheries management

Machine Learning and Meta-Analysis Approach to Identify Patient Comorbidities and Symptoms that Increased Risk of Mortality in COVID-19

Background: Providing appropriate care for people suffering from COVID-19, the disease caused by the pandemic SARS-CoV-2 virus is a significant global challenge. Many individuals who become infected have pre-existing conditions that may interact with COVID-19 to increase symptom severity and mortality risk. COVID-19 patient comorbidities are likely to be informative about individual risk of severe illness and mortality. Accurately determining how comorbidities are associated with severe symptoms and mortality would thus greatly assist in COVID-19 care planning and provision. Methods: To assess the interaction of patient comorbidities with COVID-19 severity and mortality we performed a meta-analysis of the published global literature, and machine learning predictive analysis using an aggregated COVID-19 global dataset. Results: Our meta-analysis identified chronic obstructive pulmonary disease (COPD), cerebrovascular disease (CEVD), cardiovascular disease (CVD), type 2 diabetes, malignancy, and hypertension as most significantly associated with COVID-19 severity in the current published literature. Machine learning classification using novel aggregated cohort data similarly found COPD, CVD, CKD, type 2 diabetes, malignancy and hypertension, as well as asthma, as the most significant features for classifying those deceased versus those who survived COVID-19. While age and gender were the most significant predictor of mortality, in terms of symptom-comorbidity combinations, it was observed that Pneumonia-Hypertension, Pneumonia-Diabetes and Acute Respiratory Distress Syndrome (ARDS)-Hypertension showed the most significant effects on COVID-19 mortality. Conclusions: These results highlight patient cohorts most at risk of COVID-19 related severe morbidity and mortality which have implications for prioritization of hospital resources