Intrinsic Josephson Effects in the Magnetic Superconductor RuSr2GdCu2O8

We have measured interlayer current transport in small sized RuSr2GdCu2O8 single crystals. We find a clear intrinsic Josephson effect showing that the material acts as a natural superconductor-insulator-ferromagnet-insulator-superconductor superlattice. So far, we detected no unconventional behavior due to the magnetism of the RuO2 layers.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let

The determinants of pollution levels: Firm-level evidence from Chinese manufacturing

Using a large, unique, firm-level dataset from the Chinese manufacturing sector, we study important factors that are related to emission intensity for three pollutants in China – sulfur dioxide, wastewater, and soot. Our main findings are as follows: (1) compared to state-owned enterprises (SOEs), both foreign-owned firms and domestic public-listed firms exhibit less intensive pollutant emissions; (2) firms in regions with less local protection have lower pollution intensity; (3) better property rights protection is negatively correlated with pollutant discharge over and beyond the national standards; and (4) larger firms, firms in industries that export more, and firms with more educated employees pollute less. These results suggest that China should not target foreign firms more harshly in its effort to reduce industrial pollution. Better institutions in the form of more effective law enforcement and lower entry barriers across regional markets are also means of curbing China’s pressing environmental problems during its current stage of economic development.postprin

Frequency Locking in Spatially Extended Systems

A variant of the complex Ginzburg-Landau equation is used to investigate the frequency locking phenomena in spatially extended systems. With appropriate parameter values, a variety of frequency-locked patterns including flats, $\pi$ fronts, labyrinths and $2\pi/3$ fronts emerge. We show that in spatially extended systems, frequency locking can be enhanced or suppressed by diffusive coupling. Novel patterns such as chaotically bursting domains and target patterns are also observed during the transition to locking

Long-term X-ray Variability of Ultraluminous X-ray Sources

Long-term X-ray modulations on timescales from tens to hundreds of days have been widely studied for X-ray binaries located in the Milky Way and the Magellanic Clouds. For other nearby galaxies, only the most luminous X-ray sources can be monitored with dedicated observations. We here present the first systematic study of long-term X-ray variability of four ultraluminous X-ray sources (ESO 243-49 HLX-1, Holmberg IX X-1, M81 X-6, and NGC 5408 X-1) monitored with Swift. By using various dynamic techniques to analyse their light curves, we find several interesting low-frequency quasi-periodicities. Although the periodic signals may not represent any stable orbital modulations, these detections reveal that such long-term regular patterns may be related to superorbital periods and structure of the accretion discs. In particular, we show that the outburst recurrence time of ESO 243-49 HLX-1 varies over time and suggest that it may not be the orbital period. Instead, it may be due to some kinds of precession, and the true binary period is expected to be much shorter.Comment: 15 pages, 8 figures; accepted for publication in MNRA