A study of the effects of measurement error in survey sampling

The effects of measurement error in survey sampling are investigated. Let y(,jt) be the value of the characteristic under study for the j(\u27th) unit in the population, observed at the t(\u27th) trial. Assume that; y(,jt) = Y(,j) + e(,jt);where Y(,j) is the true value of the j(\u27th) unit, and e(,jt) the deviation from the true value. It is desired to estimate the population mean of y. We study two measurement error models. The first model, called the simple correlation model, is given by;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);and; Cov(e(,jt), e(,j\u27t)(VBAR)j, j\u27) = (rho) (sigma)(,j)(sigma)(,j\u27);The second model, called the intrasample correlation model, is given by;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);and;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);for j (NOT=) j\u27, and both j, j\u27 in the sample;The usual unbiased estimators in equal and unequal probability sampling with replacement are studied under the simple correlation model. The Horvitz-Thompson estimator and the simple mean are also examined under the simple correlation model. Some of these estimators are compared in an empirical study;The ratio estimator is studied under two sampling schemes, namely, simple random sampling without replacement and Midzuno\u27s scheme. The bias and mean-square error of the ratio estimator under these two sampling schemes and the two measurement error models are derived and compared. The conditions under which one strategy is better than the other, when measurement error is present, are obtained. Also, the comparison is made in an empirical study;The results are extended to two-stage sampling and stratified sampling

A comparative study of experimental and computed compressibility factors of methane - nitrogen - helium system

The volumetric data for methane, nitrogen, and helium mixtures have been determined experimentally at low temperatures (60ºF to -30ºF) over a pressure range of 1000 to 5000 psig. An attempt has been made to show that the extension of standard techniques viz, The Law of Corresponding States for predicting the compressibility factors of pure hydrocarbons and hydrocarbon mixtures is not adequate for mixtures containing even very small amounts of helium. The deviation from the computed compressibility factors is found to be maximum at low temperatures and high pressures (up to 22%) for the mixtures studied --Abstract, page ii

Recent Advances on Metal Oxide Based Nano-Photocatalysts as Potential Antibacterial and Antiviral Agents

Photocatalysis, a unique process that occurs in the presence of light radiation, can potentially be utilized to control environmental pollution, and improve the health of society. Photocatalytic removal, or disinfection, of chemical and biological species has been known for decades; however, its extension to indoor environments in public places has always been challenging. Many efforts have been made in this direction in the last two–three years since the COVID-19 pandemic started. Furthermore, the development of efficient photocatalytic nanomaterials through modifications to improve their photoactivity under ambient conditions for fighting with such a pandemic situation is a high research priority. In recent years, several metal oxides-based nano-photocatalysts have been designed to work efficiently in outdoor and indoor environments for the photocatalytic disinfection of biological species. The present review briefly discusses the advances made in the last two to three years for photocatalytic viral and bacterial disinfections. Moreover, emphasis has been given to the tailoring of such nano-photocatalysts in disinfecting surfaces, air, and water to stop viral/bacterial infection in the indoor environment. The role of such nano-photocatalysts in the photocatalytic disinfection of COVID-19 has also been highlighted with their future applicability in controlling such pandemics

Relationship between the sonographic foetal lung-to-liver ratio of mean grey level and progesterone concentration in canine late gestation

A study was conducted to perform the quantitative analysis of canine foetal lung and liver sonographic images in the late term of gestation (58-67 days) and to evaluate its association with serum progesterone concentration. Thirty-two pregnant bitches were selected for the study. Lung development of foetus occurs in three different stages viz the pseudo glandular (40-48), canalicular (49-56 d) and saccular phase (57-63 d) of pregnancy. Lungs of the foetus at the time of parturition are in saccular phase of development and the alveolar phase occurs in the neonatal period. In the present study, sonographic changes occurring in the lung during the saccular phase of foetal lung development was evaluated. Mean grey level of the foetal lung and liver sonographic images were estimated using dedicated image analysis software Image J. The lung-to-liver ratio (LLR) of mean grey level (MGL) was recorded. Corresponding progesterone concentrations were also estimated for each animal. Correlation statistical analysis revealed a significant correlation between LLR of MGL and progesterone concentration in the animals selected for the study. LLR of MGL is a prognostic indicator of foetal survival and since LLR of MGL and progesterone are positively correlated, it can be used as an indicator of foetal maturity in place of progesterone concentration. Keywords: Lung-to-liver ratio of mean grey level, ultrasonography, progesteron

Preparation of silica, surface characterization and adsorption at oxide/aqueous interface.

Preparation of silica, surface characterization and adsorption at oxide/aqueous interface