What is the nature of RX J0720.4–3125?

RX J0720.4–3125 has recently been identified as a pulsating soft X-ray source in the ROSAT all-sky survey with a period of 8.391 s. Its spectrum is well characterized by a blackbody with a temperature of 8 × 10⁵ K. We propose that the radiation from this object is thermal emission from a cooling neutron star. For this blackbody temperature we can obtain a robust estimate of the object's age of ∼ 3 × 10⁵ yr, yielding a polar field ∼ 10¹⁴ G for magnetic dipole spin-down and a value of P compatible with current observations.     

RCW 103 — revisiting a cooling neutron star

Recent observations of the compact source embedded within the supernova remnant RCW 103 rekindle interest in the origin of this object's emission. We contrast several models in which neutron-star cooling powers RCW 103. Specifically, either the presence of an accreted envelope or a sufficiently intense magnetic field can account for the X-ray emission from this object.     

Detection of pre-main-sequence binaries using spectro-astrometry

The technique of spectro-astrometry (measuring the wavelength dependence of the position of an object) has been used to observe a number of pre-main-sequence stars. Several previously known binaries with separations down to 100 milliarcseconds (mas) were easily detected in these observations by the presence of a broad feature in the position spectrum on the Hα line. The observations show that T CrA is a pre-main-sequence binary with a PA of 275°, and a separation of at least 140 mas. The binary period may be short enough for orbital motion to be detectable. The technique has the potential to find new binaries with smaller separations than have been possible by other methods. The observations can also reveal small-scale structure associated with the outflows in these systems as is clearly seen by the detection of structure corresponding to the jet in Z CMa.     

Temporal variability of disturbances: is this important for diversity and structure of marine fouling assemblages?

Natural communities are constantly changing due to a variety of interacting external processes and the temporal occurrence and intensity of these processes can have important implications for the diversity and structure of marine sessile assemblages. In this study, we investigated the effects of temporal variation in a disturbance regime, as well as the specific timing of events within different regimes, on the composition and diversity of marine subtidal fouling assemblages. We did this in a multi‐factorial experiment using artificial settlement tiles deployed at two sites on the North East coast of England. We found that although there were significant effects of disturbances on the composition of assemblages, there were no effects of either the variation in the disturbance regime or the specific timing of events on the diversity or assemblage composition at either site. In contrast to recent implications we conclude that in marine fouling assemblages, the variability in disturbance regimes (as a driving force) is unimportant, while disturbance itself is an important force for structuring robust ecosystems.     

Assessing the Potential of Low-Impact Development Techniques on Runoff and Streamflow in the Templeton Gap Watershed,Colorado

This study examines how the impact of impervious surface in the Templeton Gap watershed (Colorado) could be reduced through the use of low-impact development (LID) strategies. LID is a sustainable stormwater approach to land management that retains runoff close to the source by preserving natural landscape features and limiting imperviousness. Our research indicates that LID techniques could reduce peak flows generated by stormwater runoff, allow city engineers to restore the stream channel to a more natural state, and improve the safety of residents and the security of property below the levee. This study developed a model of the Templeton Gap watershed and its associated stormwater infrastructure using the Stormwater Management Model (SWMM) developed by the U.S. Environmental Protection Agency (EPA). Specifically designed for small urban watersheds, SWMM allows users to accurately represent stormwater runoff dynamics and project the impact of hypothetical LID features such as porous pavement, rain gardens, and infiltration trenches on runoff and streamflow.     

Seeing ghosts: parsing China’s “ghost city” controversy

Controversy has arisen in recent years over the creation of so-called “ghost cities” across China. The ghost city term tends to describe large-scale urban areas, sometimes planned as new towns, featuring an abundance of new built space and appearing to also have extremely low tenancy. This article examines key questions related to the ghost city phenomenon, such as: what is a ghost city? Are ghost cities driven by a tendency toward over-supply in housing? How are local-level political incentives aligned to foster the production of ghost cities? Are ghost cities temporary anomalies or structural features of China’s urban-led economic growth model? We discuss recent scholarly research into ghost cities and present original findings to show how an excess of urban space may plague certain Chinese cities.