Vegetated roofs in boreal climate support mobile open habitat arthropods,with differentiation between meadow and succulent roofs

Urban Ecosystems - Vegetated roofs are hoped to benefit urban wildlife, yet there are few empirical results regarding the conservation potential of such roofs. In this paper, we focus on arthropods...     

Stationary distributions for a class of Markov-modulated tandem fluid queues

ABSTRACT

We consider a model consisting of two fluid queues driven by the same background continuous-time Markov chain, such that the rates of change of the fluid in the second queue depend on whether the first queue is empty or not: when the first queue is nonempty, the content of the second queue increases, and when the first queue is empty, the content of the second queue decreases.

We analyze the stationary distribution of this tandem model using operator-analytic methods. The various densities (or Laplace–Stieltjes transforms thereof) and probability masses involved in this stationary distribution are expressed in terms of the stationary distribution of some embedded process. To find the latter from the (known) transition kernel, we propose a numerical procedure based on discretization and truncation. For some examples we show the method works well, although its performance is clearly affected by the quality of these approximations, both in terms of accuracy and run time.     

The Life Satisfaction Advantage of Being Married and Gender Specialization

This investigation examined whether the life satisfaction advantage of married over unmarried people decreased over the past 3 decades and whether the changes in contextual gender specialization explained this trend. Contextual gender specialization was defined as a country‐year‐specific share of married women who fully specialize in household work. The author used representative data from the World Values Survey–European Values Study integrated data set for 87 countries (N = 292,525) covering a period of 29 years (1981–2009). The results showed that the life satisfaction advantage of being married decreased over time among men but not among women. Furthermore, the decline of contextual gender specialization correlated with this trend in developed but not in developing countries. In developed countries the life satisfaction of unmarried people increased as the contextual gender specialization declined, whereas the life satisfaction of married people was not affected.     

The relationship between: occupational status,biological condition and androgen hormone level among Polish adult men: the Wroclaw Male Study

Population health and its determinants are one of the major challenges to social and economic policy. The aim of this study was to investigate the relationship between occupational activity and biological condition in adult working Polish men. The participants of the study were 300 men (30–65 years), healthy inhabitants of the city of Wroclaw, Poland. Seventeen measures of biological condition were examined. The subjects were divided into three different occupational groups: professionals, soldiers and skilled workers. A comparison of biological age profiles of three occupational groups showed that in the majority of characteristics, professionals had the youngest biological age, whereas skilled workers had the highest biological age. The results for soldiers were not as unambiguous, but biological parameters were generally closer to those for professionals. Inborn biological predispositions and long-term impact of the working environment can influence on the biological condition of various professional groups. Knowledge of the determinants of biological condition might result in efficient use of predisposition to work or may be of help in extending their time of work ability.     

Approximation of the Fisher price index by using Lowe,Young, and AG Mean indices

The Consumer Price Index (CPI) approximates changes in the costs of household consumption assuming the constant utility (COLI, Cost of Living Index). In practice, the Laspeyres price index is used to measure the CPI despite the fact that many economists consider the superlative indices to be the best approximation of COLI. The Fisher index is one of the superlative indices and additionally it satisfies most of tests from the axiomatic price index theory. Nevertheless, the Fisher price index makes use of current-period expenditure data and its usefulness in CPI measurement is limited. In this article, we verify the utility of using the Lowe, Young, and AG Mean indices for Fisher price index approximation. We confirm this utility in a simulation study and we provide an empirical proof.     

Sharp bounds on the expectations of L-statistics expressed in the Gini mean difference units

We describe a method of calculating sharp lower and upper bounds on the expectations of arbitrary, properly centered L-statistics expressed in the Gini mean difference units of the original i.i.d. observations. Precise values of bounds are derived for the single-order statistics, their differences, and some examples of L-estimators. We also present the families of discrete distributions which attain the bounds, possibly in the limit.     

Vendor Performance and Alternative Manufacturing Environments*

Today, many American firms are demanding a high level of performance from their major suppliers while at the same time reducing the number of them. Vendor performance is an important aspect of maintaining low production costs and high product quality. In this study, we examine the effects of poor vendor quality and vendor lead time uncertainty in a variety of manufacturing environments using a comprehensive simulation model. The results indicate that the effect of poor vendor performance on various manufacturing firms depends on the number of stocking points and the degree of component commonality. Moreover, disruption of the manufacturing system caused by poor vendor performance can be manifested in higher levels of inventory and order backlogs. We introduce the concept of supplyside uncertainty, as it relates to component-part commonality, to demonstrate that in certain environments commonality reduces order backlogs but increases total inventories and creates an environment that is very sensitive to vendor quality problems. Finally, several conjectures are posited for future research.     

A Secretary Problem with Many Lives

We consider a secretary type problem where an administrator who has only one on-line choice in m consecutive searches has to choose the best candidate in one of them.