Missing time with parents: son preference among Asians in the USA

We study prevalence of son preference in families of East and South Asian origin living in the USA by investigating parental time investments in children using American Time Use Surveys. Estimates show that East and South Asian mothers spend an additional hour of quality time per day with their young (aged 0–2 years) sons than with young daughters; son preference in mothers’ time allocation declines as children get older. East and South Asian fathers’ time with young children is gender neutral. We find gender specialization in time with children aged 6–17 with fathers spending more time with sons and mothers spending more time with daughters.     

Dynamic heterogeneity: a framework to promote ecological integration and hypothesis generation in urban systems

Urban areas are understood to be extraordinarily spatially heterogeneous. Spatial heterogeneity, and its causes, consequences, and changes, are central to ecological science. The social sciences and urban design and planning professions also include spatial heterogeneity as a key concern. However, urban ecology, as a pursuit that integrates across these disciplines, lacks a theoretical framework that synthesizes the diverse and important aspects of heterogeneity. This paper presents the concept of dynamic heterogeneity as a tool to explore how social and ecological heterogeneities interact and how they together act as both an outcome of past interactions and a driver future heterogeneity and system functions. To accomplish this goal, we relate heterogeneity to the fundamental concept of the human ecosystem. The human ecosystem concept identifies key processes that require operationalized models of dynamic heterogeneity in three process realms: the flow of materials, the assembly of urban ecosystem biota, and the locational choices humans make concerning land. We exemplify a specific dynamic model of heterogeneity in each of these realms, and indicate a range of complementary statistical approaches to integrate the drivers and outcomes of dynamic heterogeneity across the three realms. We synthesize a hierarchical framework for a theory of dynamic urban heterogeneity, noting its complementarity to other major urban theories and general model approaches. We hypothesize that human actions and structures amplify the dynamics of heterogeneity in urban systems.     

Multi-stage estimation of the common location parameter of several exponential distributions

The problem of constructing a confidence interval of ‘preassigned width and coverage probability’ considered by Costanza/ Hamdy and Son(1986) is further analyzed. Several multi-stage estimation procedures [ like, purely sequential, accelerated sequential and three-stage procedures ] are utilized to deal with the same estimation problem. The relative advantages and disadvantages of these procedures are discussed.     

A unified approach to stochastic comparisons of multivariate mixture models

In this paper, we consider a unified approach to stochastic comparisons of random vectors corresponding to two general multivariate mixture models. These stochastic comparisons are made with respect to multivariate hazard rate, reversed hazard rate and likelihood ratio orders. As an application, results are presented for stochastic comparisons of generalized multivariate frailty models.     

On two-dimensional optimal controlled nearest proportional to size sampling designs

Using quadratic programming and utilizing the concept of ‘nearest proportional to size sampling design’, we propose a method for two-dimensional optimal controlled selection, which ensures zero probability to non-preferred samples. An alternative strategy for estimation of population total and variance is also suggested. The utility of the proposed procedure is demonstrated with the help of examples.     

Simultaneous selection of extreme populations:a bayesian approach

The problem of simultaneously selecting two non-empty subsets, S_Land S_U, of k populations which contain the lower extreme population (LEP) and the upper extreme population (UEP), respectively, is considered. Unknown parameters θ₁,…,θ_kcharacterize the populations π₁,…,π_kand the populations associated with θ_[1]=min θ_i. and θ_[k]= max θ_i. are called the LEP and the UEP, respectively. It is assumed that the underlying distributions possess the monotone likelihood ratio property and that the prior distribution of θ= (θ₁,…,θ_k) is exchangeable. The Bayes rule with respect to a general loss function is obtained. Bayes rule with respect to a semi-additive and non-negative loss function is also determined and it is shown that it is minimax and admissible. When the selected subsets are required to be disjoint, it shown that the Bayes rule with respect to a specific loss function can be obtained by comparing certain computable integrals, Application to normal distributions with unknown means θ₁,…,θ_kand a common known variance is also considered.     

Some remarks on classical and bayesian reliability estimation of binomial and poisson distributions

The problems of estimating the reliability function and Pr{X₁+...+X_k ≤ Y} are considered. The random variables X’s and Y are assumed to follow binomial and Poisson distributions. Classical estimators available in the literature are discussed and Bayes estimators are derived. In order to obtain the estimators of these parametric functions, the basic role is played by the estimators of factorial moments of the two distributions.     

Habitat-wise distribution of the House Sparrow (<Emphasis Type="Italic">Passer domesticus</Emphasis>) in Delhi,India

Recently, there have been several reports from different parts of the World on the declining populations of the House Sparrow (Passer domesticus). In order to assess the population of this species in the National Capital Territory of Delhi-India, this study was conducted during June– August in 2007. Twenty-eight Fixed-Radius Point Count stations were established in five habitat types viz. High-density Urban Area, Medium-density Urban Area, Low-density Urban Area, Agriculture Area, and Forested Area, within the study area. The results show that the House Sparrow is still a dominant species in the agriculture area. However, its density is very low in the urban areas as compared to the other co-occurring common bird species viz. Rock Pigeon (Columba livia domestica), House Crow (Corvus splendens) and Common Myna (Acridotheres tristis). As, this study was conducted only over one season, the data is not sufficient to provide a clear picture of the population trend of the House Sparrow. Further studies are therefore required to investigate the relationship of the House Sparrow with other co-occurring common species, and to analyse the data on the type and quality of greenspaces and their relation with the House Sparrow in the study area. A long-term monitoring and conservation programme involving local people may be a good approach for maintaining the population of House Sparrow in the study area.     

Social-ecological science in the humane metropolis

The Humane metropolis is a rubric to summarize and promote environmental and social quality in contemporary urban mosaics. Because cities, suburbs, and exurbs, as spatially extensive and connected socio-ecological systems, exhibit many negative features, the humane metropolis identifies a strategy to combat the ills and instill more positive and sustainable features and processes in urban systems. Because the humane metropolis as a program has arisen primarily from social motivations, there is the opportunity to articulate more explicitly the role that science can play in addressing the humane metropolis program and evaluating its success. A humane metropolis can be summarized as one that 1) protects and restores ecological services in cities and suburbs, 2) promotes physical and mental health and safety of residents, 3) enhances efficiency by conserving energy, matter, water, and time, 4) facilitates equity by being inclusive, as well as socially and environmentally just, and 5) maintains a sense of community and a sense of place. We clarify the nature of science as a contributor to the social program, pointing out the social values motivating science, and the role that scientific knowledge and metaphor play in linking science with the social program of the humane metropolis. We further identify roles that socio-ecological research can play in meeting the goals of the humane metropolis. We use examples of environmental history, watershed function and restoration, and environmental justice research and action from the Baltimore Ecosystem Study, Long-Term Ecological Research program. The humane metropolis as a social program benefits from scientific contributions that 1) expose hidden ecological processes in urban systems, 2) generate knowledge connecting people and institutions to the biophysical environment, 3) contribute to the civic dialog, and 4) bring scientific values to the prioritization and balancing of the goals of the humane metropolis.