This article outlines the research progress on radiocarbon (14C) dating of the Erlitou site. The Erlitou site, belonging to the Bronze Age, located in Yanshi, Henan province, China, was discovered by archaeologists in 1959 when they investigated the Xia people’s remains in the area where the Xia people lived according to the records of ancient documents. Since then, there has been a standing debate about whether the site belongs to the Xia or Shang dynasty. By the mid-1990s, several hundred discussion articles on the issue had been published, but the question was still unresolved. Therefore, evidence from the chronology has attracted a great amount of attention. The dating of the Erlitou site began in the 1970s, and since the Xia-Shang-Zhou Chronology Project began in the mid-1990s, by application of wiggle-matching on the basis of improving the dating accuracy, the date of the Erlitou site has gradually become clear, which provides a basis for the archaeological research on the Xia and Shang dynasties.

A ship's perception of risk is an important basis for collision avoidance. To improve such perception, several risk measurement parameters on the ship domain are determined, including the approach factor, the time to domain violation (TDV) and the possible collision domain. Then, a risk hierarchy prewarning (RHP) model based on the violation detection of a ship domain is proposed, in which a two-level alarm scheme is adopted accordingly. A low-intensity alarm will be activated by reaching the minimum approach factor and the TDV threshold, and a high-intensity alarm will be activated by the factor of the possible collision domain and the TDV threshold. Subsequently, a novel guard zone in ARPA radar utilising the RHP model has been developed to establish a ship's risk perception system for officers on watch at sea. The model proposed in this paper can not only enhance the veracity of risk assessment around our own ship, but also be used as a decision support system for collision avoidance.

The secondary instabilities of stationary cross-flow vortices in a Mach 6 swept wing flow are studied using Floquet theory. High-frequency secondary instability modes of ‘y’ mode on top of stationary cross-flow vortices, and ‘z’ mode concentrating on the shoulder of the stationary cross-flow vortex are found. The most unstable secondary instability mode is always the ‘z’ mode as in incompressible swept wing flows. A new secondary instability mode concentrating on the trough of the stationary cross-flow vortex is found. The balance analysis of disturbance kinetic energy shows that the new mode belongs to the class of ‘y’ mode. The growth rate of the new ‘y’ mode located on the trough of the stationary cross-flow vortex is significantly larger than that of the ‘y’ mode on top of the stationary cross-flow vortex, and is comparable with the growth rate of the ‘z’ mode. It is also found that the new ‘y’ mode with higher frequency can evolve into the ‘z’ mode further downstream. The role of the pressure fluctuation term, including the pressure diffusion and pressure dilatation, in the energy production of secondary instability modes, is also investigated. It is shown that the pressure diffusion will only enhance the growth rate of the ‘z’ mode with higher frequency, but has little influence on other types of secondary instability mode. However, the pressure dilatation term arising from non-vanishing velocity divergence will reduce the growth rates of all secondary instability modes.

Global warming is causing widespread glacier retreat, with small glaciers disappearing. We investigate changes in glaciers over the western Lenglongling mountains, located in the northeastern margin of the Tibetan Plateau. Glacier extent over the western Lenglongling mountains is estimated by comparing digitized glacier outlines obtained from aerial photographs and satellite imagery. These results suggest that all 179 glaciers in the western Lenglongling mountains shrunk between 1972 and 2007. The total area loss was ~24.4 km2, accounting for ~28.3% (0.81% a-1) of the glacierized area in 1972. The average area retreat rates differ over different time intervals: they are approximately 0.68, 0.90, 0.77 and 0.56 km2 a-1 over the periods 1972-95,1995-99,1999-2002 and 2002-07, respectively. Based on analysis of meteorological data, glacier shrinkage in the study area can probably be attributed to the increase in air temperature. Furthermore, the smaller glaciers display a higher shrinkage rate than larger glaciers, and glaciers on southwest-facing slopes appear to retreat faster than those on northeast- facing slopes.

The study reported in this Research Communication was carried out to examine how parity and milking time affected donkey milk yield under a typical Chinese production system. Eighteen Jiangyue breed donkeys with good health condition, aged between 6 and 9 years, and with parities 3 and 4, were selected. Milk production was measured commencing from the fourth week post-foaling, with a total data collection of 170 d in milk (lactation length). Mean milk yield of the donkeys used in this study was 3·0 kg/donkey/d. Results showed milk yield decreased with days in milk from 3·3 kg/donkey/d at the start of the study, to 2·2 kg/donkey/d by the end of the 170 d. Parity 3 donkeys produced 22% more milk than parity 4 donkeys (3·3 kg/donkey/d vs 2·7 kg/donkey/d). The information provided by this study should aid producers in estimating the expected milk yields from individual donkey, and better predict milk yield over the course of a production cycle.

As an important biological messenger, nitric oxide (NO) exhibits a wide range of effects during physiological and pathophysiological processes, including mammalian oocyte meiotic maturation. The present study investigated whether NO derived from two nitric oxide synthase (NOS) isoforms, inducible NOS (iNOS) or endothelial NOS (eNOS), is involved in the meiotic maturation of porcine oocytes. Meanwhile, the cumulus cells' function in meiotic maturation and their interaction with oocyte development and degeneration were also investigated using cumulus-enclosed oocytes (CEOs) and denuded oocytes (DOs). Different inhibitors for NOS were supplemented to the medium. Cumulus expansion, cumulus cell DNA fragmentation and oocyte meiotic resumption were evaluated 48 h after incubation. Aminoguanidine (AG), a selective inhibitor for iNOS, suppressed cumulus expansion and inhibited CEOs to resume meiosis (p<0.05), but did not inhibit cumulus cell DNA fragmentation. Both Nω-nitro-L-arginine (L-NNA) and Nω-nitro-L-arginine methyl ester (L-NAME), inhibitors for both iNOS and eNOS, delayed cumulus expansion, inhibited cumulus cell DNA fragmentation and inhibited CEOs to resume meiosis. Such effects were not seen in DOs. These results indicate that iNOS-derived NO is necessary for cumulus expansion and meiotic maturation by mediating the function of the surrounding cumulus cells, and eNOS-derived NO is also involved in porcine meiotic maturation.

For any bounded linear operator A in a Banach space, two generalized condition numbers, k(A) and k(A) are defined in this paper. These condition numbers may be applied to the perturbation analysis for the solution of ill-posed differential equations and bounded linear operator equations in infinite dimensional Banach spaces. Different expressions for the two generalized condition numbers are discussed in this paper and applied to the perturbation analysis of the operator equation.

This paper investigates fourth-order superlinear singular two-point boundary value problems and obtains necessary and sufficient conditions for existence of C2 or C3 positive solutions on the closed interval.

This paper reviewed the recent progress in the environmental embrittlement of suicide. On the surface of suicides, the Si in the suicides such as Fe3(Si,Al) alloy reacts with both oxygen and water vapor more easy than with iron. A molecular hydrogen machanism of surface reaction, i. e. Si + 2H2O = SiO2 + 2H2, can be derived. The moisture-induced embrittlement of suicides can be considered to be an embrittlement in a localized high pressure molecular hydrogen condition. It is a kinetic hydrogen gas embrittlement. Suicides may have more severely intrinsic brittleness than iron aluminides due to their special electronic structure and bonding mechanism, leading to elucidate the role of environment on ductility with difficulty. The improvement of both the intrinsic brittleness and moisture-induced embrittlement are critical for the development of suicides.