Urban and peri-urban aquaculture as an immediate source of food fish: Perspectives of Dhaka City,Bangladesh

This paper describes the present status of aquaculture activities in Dhaka City and its surrounding areas including the system of fish marketing and distribution and environmental and socioeconomic issues. Dhaka City contains over 10 million people and is expanding day by day. Demand of fish in the last 10 years has increased as a result of increases in population and income levels. The annual per capita consumption of fish is reported to drop by 0.5 kg since 1985. The reason for this decline is increased prices and decreased supply of fish. Fish supply to the city comes from catch in the rivers-estuaries and floodlands of Dhaka district, neighboring districts, imports from other areas and aquaculture in surrounding areas of the city. Considerable quantities of fish are imported from India, Myanmar and Thailand. Seasonal patterns are common both in supply and consumption of fish. Along with traditional rural household aquaculture, in recent years, urban and peri-urban aquaculture has also been popular. Three broad types of aquaculture activities are found in and around Dhaka City; these are polyculture of carp in ponds, monoculture of catfishs in ponds, and pen and cage aquaculture in open waters. The carp includes both Indian major carp and Chinese carp and some minor carp. The catfish group includes mainly Thai pangas (Pangasius sutchi). Tilapia (Oreochromis niloticus) is also widely popular among the farmers. The technology used for aquaculture is improved extensive to semi-intensive. Increasing demand for fish in the city markets has encouraged the expansion of peri-urban aquaculture with a corresponding increase in the proportion of farmed fish in the markets.     

Analysis of survival data by a Weibull–Bessel distribution

In survival analysis and reliability studies, problems with random sample size arise quite frequently. More specifically, in cancer studies, the number of clonogens is unknown and the time to relapse of the cancer is defined by the minimum of the incubation times of the various clonogenic cells. In this article, we have proposed a new model where the distribution of the incubation time is taken as Weibull and the distribution of the random sample size as Bessel, giving rise to a Weibull–Bessel distribution. The maximum likelihood estimation of the model parameters is studied and a score test is developed to compare it with its special submodel, namely, exponential–Bessel distribution. To illustrate the model, two real datasets are examined, and it is shown that the proposed model, presented here, fits better than several other existing models in the literature. Extensive simulation studies are also carried out to examine the performance of the estimates.     

Performance of some new Liu parameters for the linear regression model

Abstract

This article introduces some Liu parameters in the linear regression model based on the work of Shukur, Månsson, and Sjölander. These methods of estimating the Liu parameter d increase the efficiency of Liu estimator. The comparison of proposed Liu parameters and available methods has done using Monte Carlo simulation and a real data set where the mean squared error, mean absolute error and interval estimation are considered as performance criterions. The simulation study shows that under certain conditions the proposed Liu parameters perform quite well as compared to the ordinary least squares estimator and other existing Liu parameters.     

Construction of repeated measurements designs strongly balanced for residual effects

Abstract

Repeated Measurements Designs have been widely used in agriculture, animal husbandry, education, biology, botany and engineering. Balanced or strongly balanced repeated measurements designs are useful to balance out the residual effects. In this article, some new generators and construction procedures are proposed to obtain circular strongly balanced repeated measurements designs in periods of (a) equal sizes, (b) two different sizes, and (c) three different sizes.     

An effective approach to linear calibration estimation with its applications

Abstract

The availability of some extra information, along with the actual variable of interest, may be easily accessible in different practical situations. A sensible use of the additional source may help to improve the properties of statistical techniques. In this study, we focus on the estimators for calibration and intend to propose a setup where we reply only on first two moments instead of modeling the whole distributional shape. We have proposed an estimator for linear calibration problems and investigated it under normal and skewed environments. We have partitioned its mean squared error into intrinsic and estimation components. We have observed that the bias and mean squared error of the proposed estimator are function of four dimensionless quantities. It is to be noticed that both the classical and the inverse estimators become the special cases of the proposed estimator. Moreover, the mean squared error of the proposed estimator and the exact mean squared error of the inverse estimator coincide. We have also observed that the proposed estimator performs quite well for skewed errors as well. The real data applications are also included in the study for practical considerations.     

International Academic Mobility in Chinese Academia: Opportunities and Challenges

International academic mobility is an important dimension of the internationalization of higher education institutions, which aims to enact practical changes in economies and societies. Although many studies have investigated the mobility of international students, the mobility of international academics has been less investigated, particularly in the context of mainland China. This qualitative study explores the experience of international academics in Chinese academia. The study is based on semi-structured interviews with twenty-six international academics from different countries, working at different universities in Beijing. Through a four-stage systematic analysis, the study shows that international academics’ engagement with mobility in Chinese academia can be characterized by a combination of gains and losses. This article explores how international academics view Chinese academia as either resourceful or restrictive for their academic career. It then discusses the hidden narratives concerning the challenges that international academics face in relation to mobility.