Cohort Turnover and Productivity: The July Phenomenon in Teaching Hospitals

The impact of labor turnover on productivity has received a great deal of attention in the literature on organizations. We consider the impact of cohort turnover -- the simultaneous exit of a large number of experienced employees and a similarly sized entry of new workers -- on productivity in the context of teaching hospitals. In particular, we examine the impact of the annual July turnover of house staff (i.e., residents and fellows) in American teaching hospitals on levels of resource utilization (measured by risk-adjusted length of hospital stay) and quality (measured by risk-adjusted mortality rates). Using patient-level data from roughly 700 hospitals per year over the period from 1993 to 2001, we compare monthly trends in length of stay and mortality for teaching hospitals to those for non-teaching hospitals, which, by definition, do not experience systematic turnover in July. We find that the annual house-staff turnover results in increased resource utilization (i.e., higher risk-adjusted length of hospital stay) for both minor and major teaching hospitals and decreased quality (i.e., higher risk-adjusted mortality rates) for major teaching hospitals. Further, these effects with respect to mortality are not monotonically increasing in a hospital's reliance on residents for the provision of care. In fact, the most-intensive teaching hospitals manage to avoid significant effects on mortality following this turnover. We provide a preliminary examination of the roles of supervision and worker ability in explaining the ability of the most-intensive teaching hospitals to reduce turnover's negative effect on performance.

A Reformulation of the Economic Theory of Fertility

When parents are altruistic toward children, the choices of fertility and consumption come from the maximization of a dynastic utility function. The maximization conditions imply first, an arbitrage condition for consumption across generations, and second, the equation of the benefit from an extra child to the net cost of rearing that child. These conditions imply that fertility in open economies depends positively on the world interest rate, on the degree of altruism, and on the growth of child-survival probabilities; and negatively on the rate of technical progress and the growth rate of social security. The growth of consumption across generations depends on changes in the net cost of rearing children, but not on interest rates or tirne preference. Even when we include life-cycle elements, we conclude that the growth of aggregate consumption per capita depends in the long run on the growth of consumption across generations. Thereby we show that real interest rates and growth rates of consumption per capita would be unrelated in the long run.

Barro's fertility equations: the robustness of the role of female education and income

Barro and Lee (1994) and Barro and Sala-i-Martin (1995) find that real per-capita GDP and both male and female education have important effects on fertility in their cross-country empirical studies. In order to assess the robustness of their results, their estimated models are subjected to specification and diagnostic testing, the effects on the model of using the improved Barro and Lee (1996) cross-country data on educational attainment of the population aged 15 and over are examined, and the different specifications used by Barro and Lee and by Barro and Sala-i-Martin compared. The results obtained suggest that their fertility equations do not perform well in terms of diagnostic testing, and are very sensitive to the use of different vintages of the educational attainment proxies and of the Summers-Heston cross-country income data. A robust explanation of fertility, to link with empirical growth equations, has, therefore, not yet been found; further work is required in this area

The Effects of Cardiac Specialty Hospitals on the Cost and Quality of Medical Care

The recent rise of specialty hospitals -- typically for-profit firms that are at least partially owned by physicians -- has led to substantial debate about their effects on the cost and quality of care. Advocates of specialty hospitals claim they improve quality and lower cost; critics contend they concentrate on providing profitable procedures and attracting relatively healthy patients, leaving (predominantly nonprofit) general hospitals with a less-remunerative, sicker patient population. We find support for both sides of this debate. Markets experiencing entry by a cardiac specialty hospital have lower spending for cardiac care without significantly worse clinical outcomes. In markets with a specialty hospital, however, specialty hospitals tend to attract healthier patients and provide higher levels of intensive procedures than general hospitals.

A 3D model for thickness and diffusion capacitance of emitter-base junction in a bifacial polycrystalline solar cell

Through this paper, we present n+-p-p+ solar cell. Mathematical relations describing the generated carriers’ density are expressed, using among others a new approach involving both junction and back surface recombination velocities in a 3D modelling study.Based on the normalized carriers’ density versus the base depth and operating an open circuit voltage, we study the space-charge layer thickness (Z) versus various parameters such as the grain size (g) and the grain boundaries recombination velocity (Sgb). Hence, the relationship between Z and the diffusion capacitance show that junction in the n+-p-p+ solar cell, when the columnar orientation is considered, is characterized by the plane capacitor properties

Testing stock market convergence: a non-linear factor approach

This paper applies the Phillips and Sul (Econometrica 75(6):1771–1855, 2007) method to test for convergence in stock returns to an extensive dataset including monthly stock price indices for five EU countries (Germany, France, the Netherlands, Ireland and the UK) as well as the US between 1973 and 2008. We carry out the analysis on both sectors and individual industries within sectors. As a first step, we use the Stock and Watson (J Am Stat Assoc 93(441):349–358, 1998) procedure to filter the data in order to extract the long-run component of the series; then, following Phillips and Sul (Econometrica 75(6):1771–1855, 2007), we estimate the relative transition parameters. In the case of sectoral indices we find convergence in the middle of the sample period, followed by divergence, and detect four (two large and two small) clusters. The analysis at a disaggregate, industry level again points to convergence in the middle of the sample, and subsequent divergence, but a much larger number of clusters is now found. Splitting the cross-section into two subgroups including euro area countries, the UK and the US respectively, provides evidence of a global convergence/divergence process not obviously influenced by EU policies

Effect of zaï and micro dose on root biomass and the grain and straw yield so sorghum at Tangaye in the North region in Burkina Faso

Faced with rainfall variation and the poor performance of farming practices, the North region of Burkina Faso often observed cereal deficits. Sorghum, the main staple food crop in this region, provides relatively low yields (1000 kgha-1). Furthermore, in the area, the density of the population is one of the highest in the country. In order to increase sorghum yields, a study has been carried out in the village of Tangaye by combining the water management practice through mechanized and manual zaï techniques with fertilization by microdose of NPK fertilizer. The experimental design of the study was a split-plot with three replications and four treatments set on a crusty bear soil “Zipellé”.The mechanized zaï and the manual zaï have been compared with and without applying mineral NPK fertilizer by a micro dose. The effects of these techniques have been evaluated on the soil and the root system by the method of taking monoliths. The grain and straw yields of sorghum have been evaluated for each treatment. The results showed that the greatest roots system development was obtained on the mechanized zaï plot with the application of micro dose of NPK fertilizer. This treatment also has the highest grain yield (2910 kgha-1) compared to manual Zaï (1620 kgha-1