We estimate how a rise in uncertainty about future tariff rates impacts firm decisions to enter into and exit from export markets. Using Chinese customs transactions between 2000-2009, we exploit timevariation in product-level trade policy and find that Chinese firms are less likely to enter new foreign markets and more likely to exit from established foreign markets when their products are subject to increased trade policy uncertainty. Our analysis is based on the phenomenon of "tariff echoing"-after a tariff hike in one country, another country is likely to raise its tariff on the same product. Overall, we find that if there had been no trade policy uncertainty created by the use of contingent tariffs, Chinese entry into foreign markets would have been roughly 2 percent higher per year. We use our model to counterfactually estimate how much entry by Chinese firms over 2001-2009 was due to future trade policy certainty provided by membership in the WTO.

No abstract

Although adipose‐derived mesenchymal stem cells (ADMSCs) isolated from patients’ fat are considered as the most important autologous stem cells for tissue repair, significant difficulties in the neural differentiation of ADMSCs still impede stem cell therapy for neurodegenerative diseases. Herein, a wireless‐electrical stimulation method is proposed to direct the neural differentiation of ADMSCs based on the electromagnetic effect using a graphene film as a conductive scaffold. By placing a rotating magnet on the top of a culture system without any inducer, the ADMSCs cultured on graphene differentiate into functional neurons within 15 days. As a conductive biodegradable nanomaterial, graphene film acts as a wireless electrical signal generator driven by the electromagnetic induction, and millivolt‐level voltage generated in situ provokes ADMSCs to differentiate into neurons, proved by morphological variation, extremely high levels of neuron‐specific genes, and proteins. Most importantly, Ca2+ intracellular influx is observed in these ADMSC‐derived neurons once exposure to neurotransmitters, indicating that these cells are functional neurons. This research enhances stem cell therapy for neurodegenerative diseases using autologous ADMSCs and overcomes the lack of neural stem cells. This nanostructure‐mediated physical‐signal simulation method is inexpensive, safe, and localized, and has a significant impact on neural regeneration.

We examine the stock market performance of publicly-listed Chinese firms in the solar panel industry over 2012 and 2013 in response to announcements of new import restrictions by the European Union and domestic policy changes by the Chinese government. Using daily stock market prices from the Shanghai-Shenzhen, New York and Hong Kong markets, we calculate abnormal returns to several policy changes affecting solar panels produced in China. We find, consistent with the Melitz (2003) model, that larger, more export-oriented firms experienced larger stock market losses in the wake of European trade restriction announcements. We further show that European trade policy had a larger negative effect on Chinese private sector firms relative to state owned enterprises. Finally, we use a two stage least squares estimation technique to show that firms listed on US markets are more responsive to news events than those listed in China and Hong Kong. AbstractWe examine the stock market performance of publicly-listed Chinese firms in the solar panel industry over 2012 and 2013 in response to announcements of new import restrictions by the European Union and domestic policy changes by the Chinese government. Using daily stock market prices from the Shanghai-Shenzhen, New York and Hong Kong markets, we calculate abnormal returns to several policy changes affecting solar panels produced in China. We find, consistent with the Melitz (2003) model, that larger, more export-oriented firms experienced larger stock market losses in the wake of European trade restriction announcements. We further show that European trade policy had a larger negative effect on Chinese private sector firms relative to state owned enterprises. Finally, we use a two stage least squares estimation technique to show that firms listed on US markets are more responsive to news events than those listed in China and Hong Kong. JEL Codes: F12, F13, G10, G14