The Yangtze River dolphin or baiji (Lipotes vexillifer), an obligate freshwater odontocete known only from the middle-lower Yangtze River system and neighbouring Qiantang River in eastern China, has long been recognized as one of the world's rarest and most threatened mammal species. The status of the baiji has not been investigated since the late 1990s, when the surviving population was estimated to be as low as 13 individuals. An intensive six-week multi-vessel visual and acoustic survey carried out in November-December 2006, covering the entire historical range of the baiji in the main Yangtze channel, failed to find any evidence that the species survives. We are forced to conclude that the baiji is now likely to be extinct, probably due to unsustainable by-catch in local fisheries. This represents the first global extinction of a large vertebrate for over 50 years, only the fourth disappearance of an entire mammal family since AD 1500, and the first cetacean species to be driven to extinction by human activity. Immediate and extreme measures may be necessary to prevent the extinction of other endangered cetaceans, including the sympatric Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis).

HLA-B*13:01 was associated with the development of the dapsone hypersensitivity syndrome among patients with leprosy. (Funded by the National Natural Science Foundation of China and others.).

Endangered Finless porpoise (Neophocaena phocaenoides) Line transect A B S T R A C TThe Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is endemic to the middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou ($150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems.

Pure hexagonal-phased Y 1-x BO 3 :Eu x (x ) 0-0.30) nanocrystals with different particle sizes were prepared by a facile sol-gel pyrolysis process, and their photoluminescence spectra evidently showed a size-dependent characteristic because the ratio of the red emission transition ( 5 D 0 f 7 F 2 ) to the orange emission transition ( 5 D 0 f 7 F 1 ) (R/O) was much higher in the smaller particles. Both XRD patterns and IR spectra demonstrated that the lattices of YBO 3 :Eu nanocrystals were distorted and that as the particle size became smaller, the lattices became more distorted. Studies on the charge transfer (CT) bands indicated that Eu 3+ ions can be excited preferentially by different excitation sources in both the bulk and the nanocrystals, suggesting that at least two different types of intrinsic luminescent sites, site 1 and site 2, coexist in YBO 3 :Eu. Site-selective excitation spectra also revealed that a particular site, site 3, existed concurrently in the nanocrystals. Site 2, the site with relatively inferior symmetry of the intrinsic sites, was identified to be of C 1 symmetry. Meanwhile, for the nanosized samples, Eu 3+ ions exhibited enhanced R/O values in both sites 2 and 3, which might be ascribed to the distorted lattices, and thus displayed the observed superior color chromaticity. A pronounced energy transfer between site 2 and site 3 in the nanocrystals was also observed while Eu 3+ concentration was increased to the quenching concentration, which indicated that site 3 may be a disordered surface site surrounding the interior sites.

Abstract. In this paper, we prove the decay estimates of the velocity and H 1 scattering for the 2D linearized Euler equations around a class of monotone shear flow in a finite channel. Our result is consistent with the decay rate predicted by Case in 1960.

In order to improve the color purity of YBO3:Eu, which is practically used as a plasma phosphor, the lowering of the structural symmetry is proposed and subsequently realized in nanosized YBO3:Eu so as to increase the contribution of D05–F27 transition of the luminescent centers, Eu3+ ions. Spherical YBO3:Eu nanocrystals were fabricated via thermal decomposition of complex precursors and could be crystallized at lower temperature than required by the bulks. The particle size could be controlled by adjusting the annealing temperature and time. Unlike the bulk YBO3:Eu synthesized by solid-state reaction, the quenching concentration increased with the decrease of the particle size. Furthermore, the fluorescence intensity and color purity were significantly improved in nanocrystals. Possible mechanisms responsible for these improvements were proposed.

In this paper, we prove the linear inviscid damping and voticity depletion phenomena for the linearized Euler equations around the Kolmogorov flow. These results confirm Bouchet and Morita's predictions based on numerical analysis. By using the wave operator method introduced by Li, Wei and Zhang, we solve Beck and Wayne's conjecture on the optimal enhanced dissipation rate for the 2-D linearized Navier-Stokes equations around the bar state called Kolmogorov flow. The same dissipation rate is proved for the Navier-Stokes equations if the initial velocity is included in a basin of attraction of the Kolmogorov flow with the size of ν 2 3 + , here ν is the viscosity coefficient.Here P 2 denotes the orthogonal projection of L 2 (T 2 δ ) to the subspace W 2 = span{sin y, cos y}.Remark 1.7. The stability threshold ν γ for γ > 2 3 may be not optimal. We can only achieve the stability threshold ν 3 4 if we do not use the enhanced dissipation with an extra decay factor of the velocity.Remark 1.8. The case of δ = 1 is a challenging problem. In this case, we need to consider the linearized Navier-Stokes equations around the dipole states such as e −νt (− sin y, sin x), e −νt (− cos y, cos x).

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