Stable 85Rb micro vapour cells: fabrication based on anodic bonding and application in chip-scale atomic clocks

We describe the microfabrication of ⁸⁵Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm³ internal volumes during the cell sealing process. At an ambient temperature of 90 ℃ the optical absorption resonance of ⁸⁵Rb D1 transition with proper broadening and the corresponding coherent population trapping (CPT) resonance, with a signal contrast of 1.5% and linewidth of about 1.7 kHz, have been detected. The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9-month optoelectronics measurement which shows a similar CPT signal as its original status. In addition, the physics package of chip-scale atomic clock (CSAC) based on the cell was realized. The measured frequency stability of the physics package can reach to 2.1×10^-10 at one second when the cell was heated to 100 ℃ which proved that the cell has the quality to be used in portable and battery-operated devices.     

The relationship between soft-bottom macrobenthic communities and environmental variables off Ningjin, eastern Shandong Peninsula

Macrobenthic infauna and associated environmental factors influencing the benthic community in the eastern coastal region of Shandong Peninsula were analyzed in four seasonal surveys from January 2007 to October 2007 (30 stations in winter, 20 stations in other three seasons), in order to understand the community structure and the factors unfluencing the benthic distribution. PRIMER 6.0 and SPSS 15.0 software packages were adopted to analyze the environmental and macrobenthic data. The results show that there were 260 macrobenthic species in total collected from the research region. The composition of species is:Polychaeta (94 species), Crustacea (75), Mollusca (56) and Echinoderm (12), among which, only 23 species were common species in the cruises of every season. The dominant species varied from season to season; however, the polychaete species Paralacydonia paradoxa Fauvel and Echinoderm species Amphioplus japonicus (Matsumoto) were always present year-round. The abundance and biomass of the macrobenthos in the research region were variable from season to season. The results of CLUSTER and MDS analysis show that the similarities of macrobenthic structures between the stations were low; most of the similarities were at about 30% of similarity value, only two stations were up to 70%. In accordance with the similarity values of the macrobenthic structures, we divided the 20 stations into five groups by arbitrary similarity level of 30%. The ABC curve indicates that the marcofauna communities in the research region had not been disturbed massively, except two stations, SB1 and SB3. Ecologically, benthos were controlled by a combination of factors such as salinity, phytoplankton, zooplankton, SiO₃-Si and temperature, and no single factor could be considered as an ecological master factor.     

Fishermen responses on marine protected areas in the Baltic cod fishery

Much of the research that concerns the impacts of management measures in the eastern Baltic cod fishery has focused on fish stock rather than understanding fishermen's attitudes towards regulations. Hence, there is little information available on fishermen's responses although they are the ones whom the regulations affect most profoundly. This study analyses the views of fishermen towards management measures with an emphasis on fishing closures (marine protected areas, MPAs). Swedish log-book data from 1996 to 2005 were used to describe MPA induced fishing effort displacements. Fishermen argued that MPAs have been inefficient in conservation of cod stock. The enlargement of Bornholm MPA in 2005 caused substantial effort displacement towards areas dominated by smaller sized fish. This contributed to the increased discarding of juvenile cod. Enlarged MPAs also intensified competition between different fleet segments and reallocated fishing areas. To reduce fishing mortality, fishermen suggested days-at-sea (effort) regulation and an effective landings control system for all fleets that exploit cod stocks in the Baltic Sea Main Basin. These measures would better motivate fishermen for mutual rule compliance, which is a prerequisite for a sustainable cod fishery.     

Static bay beach concept for scientists and engineers: A review

Headland-bay beach (HBB) is one of the most prominent physiographic features on the oceanic margin of many countries in the world. Under the influence of a predominant swell, its curved periphery in natural environment may reach static equilibrium and remains stable without sediment supply from updrift and/or a riverain source within its own embayment. Coastal scientists and engineers have attempted to develop mathematical expressions to quantify this ideal bay shape since the 1940s. As the scenario with depleting sediment supply has become a common reality on many parts of the world coastline in more recent time, some coastal engineers have advocated a rational approach to mimicking the static bay shape found in nature in order to mitigate beach erosion as well as for coastal management. Nowadays, many useful applications have emerged since the publication of the parabolic bay shape equation (PBSE) developed for static equilibrium planform (SEP) in late 1980s. The advance in modern computer technologies and international collaboration has further facilitated the exchange of knowledge and applications of this static bay beach concept (SBBC).     

The form of the asymptotic depth-limited wind-wave spectrum: Part III — Directional spreading

The directional spreading of both the wavenumber and frequency spectra of finite-depth wind generated waves at the asymptotic depth limit are examined. The analysis uses the Wavelet Directional Method, removing the need to assume a form for the dispersion relationship. The paper shows that both the wavenumber and frequency forms are narrowest at the spectral peak and broaden at wavenumbers (frequencies) both above and below the peak. The directional spreading of the wavenumber spectrum is bi-modal above the spectral peak. In contrast, the frequency spectrum is uni-modal. This difference is shown to be the result of energy in the wind direction being displaced from the linear dispersion shell. A full parametric relationship for the directional spreading of the wavenumber spectrum is developed. The analysis clearly shows that typical dispersion relationships are questionable at high frequencies and that such effects can be significant. This result supports greater attention being focussed on the routine recording of wavenumber spectra, rather than frequency spectra.     

Cost-effectiveness of the Baltic Sea Action Plan

The governments around the Baltic Sea have agreed on a new set of targets for nutrient load reductions. The major motive for this is new and better knowledge about the link between nutrient loads and water transparency in different parts of the sea. The Baltic Sea Action Plan (BSAP) defines target for transparency in different marine basins, the load reductions necessary to meet transparency targets and a scheme for the distribution of the abatement burden between countries adjacent to the sea.     

Comparison of long-, medium- and short-term variations of beach profiles with and without submerged geological control

Victoria Beach (Cadiz, Spain) comprises a rocky flat outcrop in its northern zone and a sand-rich southern zone. These natural features allowed for a 5-year monitoring period and subsequent analysis of two different profiles (one in each zone) based on differences in bottom contours. Topo-bathymetric data were analysed using empirical orthogonal functions (EOFs) to determine changes over the short-, medium- and long-term. Several morphologic phenomena were identified (generalised erosion, seasonal or summer–winter tilting of the profile around different hinge points, berm development and its posterior destruction, etc.) in terms of their importance in explaining the variability of the collected data for both profiles. It is worth mentioning that both profiles undergo parallel regression in the medium-term. Thus, the 1st eigenfunction enabled us to identify the true regression of the beach shoreline, independent of seasonal or summer–winter slope changes. Reconstruction of profiles using EOF components demonstrated that though accretion periods in the medium-term were similar for both types of profiles, the accretion speed was much faster in the sand-rich profile than in the reef-protected profile (1.01 m³/day versus 0.33 m³/day). Moreover, the seasonal erosion rate and the subsequent shoreline retreat for the sand-rich profile were much larger than for the reef-protected profile (121 m³/year versus 29 m³/year). Analysis in the short-term (changes induced by a single day's storm) showed an instantaneous tilting of the profile, with the mobilised sand volume being much greater for the sand-rich than for the reef-protected profile (68 m³/m versus 12 m³/m).     

基于遥感光谱反射率反演黄河口海域Ⅱ类水体悬浮泥沙浓度模型

依据黄河口海域含沙水体野外实测光谱反射率为参考实验数据,结合水体表面光谱观测数据建立了经验回归模型,从而定量估测黄河口海域水体表层悬浮泥沙质量浓度,最终得出黄河口海域不同年份水体的悬浮泥沙质量浓度图,这对分析河口海岸带冲淤变化过程具有重要的意义。     

马氏珠母贝种苗规模化繁育新技术及工艺

对马氏珠母贝人工育苗换水、投附着基和饵料等关键环节进行了研究。结果表明:(1)不换水组的D形幼虫及壳顶幼虫的存活率,稚贝育成率以及D形幼虫、壳顶幼虫及稚贝壳长日生长率比换水组分别提高了15.3%、259.6%、186.5%、33.3%、34.2%、12.4%,且差异显著;(2)第1、2次投附着板组的稚贝壳长日生长率均比一次性投附着板组快,第3次投附着板组的壳长日生长率比其他所有组均慢,且差异均显著。多次投附着板组的同一批次稚贝均匀度均比一次性投附着板组好,且多次投附着板组比一次性投附着板组的稚贝育成率提高了32.5%,稚贝存活率提高了19.3%,采苗量提高了35%;(3)投喂虾塘水组稚贝存活率、育成率及壳长日生长率比投喂50%自溶酵母+50%小球藻组分别提高了28.1%、47.2%、35.9%,而投喂这两种不同饵料的稚贝阴干后的存活率差异不显著。研究表明,通过封闭不换水育苗、多次投附着板及投喂虾塘水中的生态饵料的方法可以高效地培育出健康的马氏珠母贝种苗。     

麻痹性贝毒对肝脏和肾脏氧化损伤的影响

为了探讨麻痹性贝毒(PSP)对肝脏和肾脏损伤的机制,采用膝沟藻毒素GTX-1,4对小鼠进行急性暴露,剂量为1μg/kg,时间分别为60、90、120min。结果发现,与对照组相比,肝脏染毒组中的还原型谷胱甘肽(GSH)含量没有显著变化;在肾脏中,60 min时染毒组GSH含量没有明显变化,90、120 min时GSH含量降低;两器官中抗氧化酶(GSH-Px、SOD)活性与对照组相比均无显著变化(P0.05)。从而推断,GSH参与了PSP对肾脏损害的毒性过程;肾中GSH含量有可能作为PSP早期检测的敏感指标。