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Developmental anomalies induced by toxic chemicals may be identified using laboratory experiments with rats, mice or rabbits. Multinomial responses of fetuses from the same mother are often positively correlated, resulting in overdispersion relative to multinomial variation. In this article, a simple data transformation based on the concept of generalized design effects due to Rao‐Scott is proposed for dose‐response modeling of developmental toxicity. After scaling the original multinomial data using the average design effect, standard methods for analysis of uncorrected multinomial data can be applied. Benchmark doses derived using this approach are comparable to those obtained using generalized estimating equations with an extended Dirichlet‐trinomial covariance function to describe the dispersion of the original data. This empirical agreement, coupled with a large sample theoretical justification of the Rao‐Scott transformation, confirms the applicability of the statistical methods proposed in this article for developmental toxicity risk assessment.

Reproductive and developmental anomalies induced by toxic chemicals may be identified using laboratory experiments with small mammalian species such as rats, mice, and rabbits. In this paper, dose‐response models for correlated multinomial data arising in studies of developmental toxicity are discussed. These models provide a joint characterization of dose‐response relationships for both embryolethality and teratogenicity. Generalized estimating equations are used for model fitting, incorporating overdispersion relative to the multinomial variation due to correlation among littermates. The fitted dose‐response models are used to estimate benchmark doses in a series of experiments conducted by the U.S. National Toxicology Program. Joint analysis of prenatal death and fetal malformation using an extended Dirichlet‐trinomial covariance function to characterize overdispersion appears to have statistical and computational advantages over separate analysis of these two end points. Benchmark doses based on overall toxicity are below the minimum of those for prenatal death and fetal malformation and may, thus, be preferred for risk assessment purposes.

Using the 2013 China Education Panel Survey (CEPS), we study the impact of accessing better schools – a 2008 inclusive education policy through which the central government mandated urban public schools to exempt migrant children from tuition and temporary schooling fees. Whereas the non-disclosure rule regarding geographical location of CEPS sampling units precludes the control of locational characteristics, we identify the causal effect of the policy by exploiting constituent elements of CEPS's primary sampling units. Namely, we only use non-migrant rural hukou children living in counties in the nationally representative sample as the control group (the never-takers), while, in the treatment group, we only include migrant children who are currently living in China's top 120 migrant-receiving counties or city districts, and Shanghai. We also distinguish migrant children who started urban schooling before and after 2008 as separate treatment groups of always-takers and compliers, respectively. Using the Inverse Probability Weighted Regression Adjustment (IPWRA) approach, we find that the average treatment effect of the policy on migrant children is around 0.18 SD, as measured by a standardised cognitive test score – a large effect. We also present complementary evidence that the average treatment effect tends to be larger for municipalities and provincial capitals, consistently with the notion that the (potential) value-added of attending urban schools is higher the larger the initial gap with rural schools.

Ever since the collapse of the Bretton-Woods system, gold has retained its function as an important monetary commodity (Baur and Lucey, 2010), and continues to provide important inflation forecasting information to monetary policy setters (Tkacz, 2007). However, Capie et al. (2005) highlight the instability of gold price dynamics through time, attributing it to unpredictable political attitudes and events. In this paper, we investigate gold price dynamics under different inflation regimes and stock market conditions using UK and US index-linked Treasury bond data. We show that gold lost its role as an inflation hedge after May 1997 in the UK, and after 2003 did not act as an inflation hedge in the US, supporting the argument that gold is an inflation hedge only in periods of high inflation and inflation expectations. Further, we show that gold retained its safe haven status throughout the sample period in both countries, but it did not act as a stock market hedge in the UK except during the 2008-9 global financial crisis. Finally, we conduct an event-study analysis of the impact of QE announcements from four leading central banks on the gold price in US dollars. While the QE announcements of the US Federal Reserve and the European Central Bank exerted a strong and weak influence on gold, respectively, the Bank of England and the Bank of Japan's QE announcements had no discernible impact on the gold price.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. Communications aided by low-altitude unmanned aerial vehicles (UAVs) have emerged as an effective solution to provide large coverage and dynamic capacity for both military and civilian applications, especially in unexpected scenarios. However, because of their broad coverage, UAV communications are prone to passive eavesdropping attacks. This paper analyzes the secrecy performance of UAVs networks at the millimeter wave band and takes into account unique features of air-to-ground channels and practical constraints of UAV deployment. To be specific, it explores the 3-D antenna gain in the air-to-ground links and uses the Matérn hardcore point process to guarantee the safety distance between the randomly deployed UAV base stations. In addition, we propose the transmit jamming strategy to improve the secrecy performance in which part of UAVs send jamming signals to confound the eavesdroppers

Despite macroeconomic evidence pointing to a negative aggregate consumption response due to political uncertainty, few papers have used microeconomic panel data to analyze how households adjust their consumption after an uncertainty shock. We study household savings and expenditure adjustment from an unexpected, large-scale and rapidly evolving political shock that occurred largely in May 1989 in Beijing, China. Using monthly micro panel data, we present evidence that a surge in political uncertainty resulted in significant temporary increases in savings among urban households in China. Households responded mainly by reducing semi-durable expenditure and frequency of major durable adjustment. The uncertainty effect is more pronounced among older, wealthier, and more socially advantaged households. We interpret our findings using existing models of precautionary behavior. By focusing on time variation in uncertainty, our identification strategy avoids many of the potential problems in empirical studies of precautionary savings such as self-selection and life-cycle effects. ; This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.jce.2015.12.011