High philopatry rates of Yellow-legged Gulls in the southeastern part of the Bay of Biscay

Background:Philopatry rate is one of the main factors shaping population dynamics in colonial seabirds.Low rates of philopatry are linked to populations with high dispersal,while high rates are linked to populations with a very high spatial structure pattern(i.e.,metapopulations).The Cantabrian Yellow-legged Gull(Larus michahellis)population is considered to be resident,with relatively low dispersal rates.Precise estimations of its philopatry rates are however still lacking.Here,we aimed to estimate philopatry rates in the main Yellow-legged Gull colonies of the province of Gipuzkoa,in the southeastern part of the Bay of Biscay.Methods:We analysed 734 resightings,during the breeding season at the colonies of Getaria,Santa Clara and Ulia,relative to a total of 3245 individuals ringed at birth in these same colonies during a period of 13 years.These data were analysed using Multi-State Recapture models in MARK.Results:After controlling survival and resighting probability,the average dispersal rate among colonies was 4%(±SD=2%)when individuals are immature,decreasing to 1±1%)for adult breeding gulls(i.e.,philopatry rate was 99%).Annual survival rates were assessed to be 0.27±0.02 for birds in their first year of life and 0.87±0.01 for older individuals.The probability of observing immature birds in the colonies was 0.08±0.01,as compared to 0.21±0.02 in adult birds.Conclusions:We obtained evidence of extremely high local philopatry rates,clearly within the upper limit found in gulls.A high philopatry favour a speciation in these species who are vulnerable to obtain the main food source(land-fills and fishing discard)which are transforming under new ecological process.

Economical operation of Baosteel's oxygen generating system

Baosteel＇s 60000 m^3/h air separation unit （ASU） is the largest oxygen generating system in China. The operational cost of such a giant system is very high. How to reduce the operational cost is a critical issue. This paper discusses the system＇s characteristics,the current operational status and the difficulties in reducing the cost,and analyzes relevant indicators, such as the technical and economical indicators of individual units and systems as well as the indicators concerning the costs. The relationship between the cost and each economical indicator and measures to optimize an economical operation of the oxygen generating system are also discussed in this paper.

Linear analysis of a three-dimensional rectangular Cerenkov maser with a sheet electron beam

A linear theory of a rectangular Cerenkov maser （RCM） with a sheet electron beam is developed by using the field- match method. Based on the three-dimensional beam-wave interaction model proposed in this paper, a hybrid-mode dispersion equation and its analytical solution are derived for the RCM. Through numerical calculations, the effects of the beam-grating gap, beam thickness, current density, beam voltage and waveguide width on the linear growth rate axe analysed. Moreover, the performance difference between the RCM with the closed transverse boundary and that with the upper open boundary is compared. The results show that the closed RCM model can avoid the effect of RF radiation on beam-wave interaction, which is more rational for practical applications.

Stripping dispersion hollow fiber liquid membrane containing carrier PC-88A and HNO_3 for the extraction of Sm^(3+)

Stripping dispersion hollow fiber liquid membrane system（SDHFLM） containing feed phase adding acetate buffer solution and dispersion solution with HNO_3 solution as the stripping solution and membrane solution of 2-ethyl hexyl phosphoric acid-mono-2-ethylhexyl ester（PC-88A） dissolved in kerosene,has been studied for the extraction of Sm^（3＋）.Many factors including pH value, volume ratio of membrane solution to stripping solution（OAV） and carrier concentration on Sm^（3＋） extraction were investigated. Experimental results indicate that the optimum extraction conditions of Sm^（3＋） were obtained as that PC-88A concentration was 0.120 mol/L,and OAV was 1.00 in the dispersion phase,and pH value was 4.80 in the feed phase.When initial Sm^（3＋） concentration was 1.20×10^（-4） mol/L,the extraction percentage of Sm^（3＋） was up to 92.8%in 160 min.