Relationships between body weight and other morphological traits in young sea cucumbers Apostichopus japonicas

Correlation, multiple regression, and path analyses were used to investigate the relationships between body weight and three other morphological traits in juvenile Japanese sea cucumbers Apostichopus japonicus . We measured live body weight (BW), body length (BL), numbers of papillae (NP), and numbers of tube feet (NF) at 60, 80, 100, and 130 days post-hatching (dph). We calculated path correlation coefficients, correlation indices ( R 2 ), and coefficients of determination with BW as the dependent variable and the other morphological traits as independent variables. The coefficient of variation for BW was high across all age groups, and all measured morphological traits were significantly correlated ( P < 0.01). BL had the greatest direct eff ect on BW across all age groups (60 dph, 0.526;80 dph, 0.404;100 dph, 0.620;and 130 dph, 0.681), while NF had the greatest indirect eff ect on BW across all age groups (60 dph, 0.528;80 dph, 0.452;100 dph, 0.666;and 130 dph, 0.603). Regression analyses between morphological traits and BW indicated that R 2 was greater than 0.85 only in the 100-dph specimens. The indirect eff ects of the other measured morphological traits on BW were age-dependent. The optimal regression equations, as determined with stepwise regression, were, for 60-dph specimens: BW 60 =10 (-3.04+0.092BL+0.014NP+0.014NF)( R 2 =0.632);for 80-dph specimens: BW 80 =10 (- 3.035+0.056BL+0.017NP+0.02NF)( R 2 =0.686);for 100-dph specimens: BW 100 =10 (- 3.742+0.069BL+0. 633 · lg (NP)+0. 464 · lg (NF))( R 2 =0.893);and for 130-dph specimens: BW 130 =10 (- 2.472+0.065BL+0.012NP)( R 2 =0.774). Our work clarified the correlation between various morphological traits and body weight of a commercially-important sea cucumber species ( A . japonicus ). Our predictive models for body weight might be useful for the aquaculture and selective breeding of A . japonicus . These models might also provide theoretical support for the indirect selection of traits that are difficult to select directly.     

An efficient hybrid integral-equation method for point-absorber wave energy converters with a vertical axis of symmetry

To assist in the prototyping and controller design of point-absorber wave energy converters (WECs), an easy-to-implement hybrid integral-equation method is presented for computing the frequency-domain hydrodynamic properties of bodies with a vertical axis of symmetry in waves. The current hybrid method decomposes the flow domain into two parts: an inner domain containing the body and an outer domain extending to infinity. The solution in the inner domain is computed using the boundary-element method, and the outer-domain solution is expressed using eigenfunctions. Proper matching at the domain boundary is achieved by enforcing continuity of velocity potential and its normal derivative. Body symmetry allows efficient computation using ring sources in the inner domain. The current method is successfully applied to three different body geometries including a vertical truncated floating cylinder, the McIver toroid, and the coaxial-cylinder WEC being developed in the authors’ laboratory. In particular, the current results indicate that, by replacing the flat bottom of the coaxial-cylinder WEC with the Berkeley-Wedge (BW) shape, viscous effect can be significantly reduced with only minor negative impact on wave-exciting force, thus increasing WEC efficiency. Finally, by comparing to experimental measurements, the current method is demonstrated to accurately predict the heave added mass and wave-exciting force on the coaxial-cylinder WEC with BW geometry. If a viscous damping correction factor is used, the heave motion amplitude can also be accurately computed.     

Body motion in liquid under ice plate with snow cover

The motion of a submarine in liquid under an ice plate covered with flooded snow is considered. The ice is modelled as an elastic plate and the snow cover is modelled as a viscous layer on the top of the plate. The submarine is modelled as a slender solid of revolution with scale 1:300. The experimental and theoretical study of the influence of the viscous snow layer on deflections of the floating ice plate is conducted. The viscous layer reduces the amplitudes of flexural-gravity waves. The greatest influence of the viscous layer on the plate deflections is achieved for velocities of the submarine, where the waves of maximum amplitude are generated. Theoretical results are in good qualitative and quantitative agreement with the model experiments.     

紫刺参早期生长发育与体色形成的研究

本研究对紫刺参胚胎和幼体发育过程进行了显微观测,比较分析了其幼体早期生长情况与体色形成过程。结果表明:(1)在水温21.0±0.2℃条件下,紫刺参受精卵在受精10～15min后释放第一极体,5h 30min～6h 30min进入囊胚期, 18～20h发育成原肠胚; 30～34h进入耳状幼体阶段, 8～10d变态发育为樽形幼体, 12～14d发育成稚参;紫刺参胚胎和幼体发育时序与普通刺参无显著差异。(2)紫刺参早期发育中的樽形幼体发生率和附着变态率分别为58.4±4.7%和45.1±2.7%,高于普通刺参。(3)紫刺参浮游阶段后期随日龄增长表现出较普通刺参发育更快的优势,在日龄6～7d表现出显著差异(P0.05)。(4)紫刺参稚参在日龄35d前后自背部开始着色,50d～60d腹部开始着色,110d体表紫色转变近乎成参体色,完成变色过程。     

基于PNAT描述的三维地籍ArcEngine开发方法

针对三维地籍对二维数据兼容不良问题,本文基于PNAT模型,利用ArcEngine开发出城镇三维地籍系统。通过对三维地籍要素进行描述与表达,推演出地上地下三维宗地体,并在ArcGIS中构造出三维宗地体模型。实验证明,运用ArcEngine开发的三维地籍系统,可完美兼容已有二维地籍数据,极大地减少了开发成本,提高了效率,同时系统兼具ArcGIS提供的分析功能,稍加改进即可实现自定义查询,实现三维地籍图属联合分析。基于ArcEngine的三维地籍开发是一种效率高、功能丰富的二次开发方法,其数据兼容性及空间分析功能明显优于其他非GIS二次开发平台。     

Effect of Dietary Phosphorus on the Growth and Body Components of Juvenile Synechogobius hasta

The effect of dietary phosphorus on the growth and body components of juvenile Synechogobius hasta was determined. Different percentages of dietary phosphorus (0.63, 0.77, 0.93, 1.06, 1.22 and 1.36) were tested by feeding the fish (body weight, 15.81 g ± 0.32 g; 20 individuals each group; 3 groups each percentage) at a surplus of 5%–10% above satiation for 35 d. Dietary phosphorus did not significantly affect the specific growth rate, feed intake, feed conversion ratio and protein efficiency rate. Nitrogen ...     

Numerical prediction of MODUs drift during Hurricane Katrina

Severe hurricanes, such as Katrina, broke the mooring lines of a number of mobile offshore drilling units (MODU) deployed in the Gulf of Mexico and some of those MODUs went adrift. A drifting MODU may damage other critical elements of the offshore oil and gas infrastructure by colliding with floating or fixed production systems and transportation hubs, or by rupturing pipelines owing to their dragging anchors over the seabed. To avoid or mitigate the damage caused by a drifting MODU, it is desirable to understand the mechanics of the drift of a MODU under the impact of severe wind, wave and current and have the capability of predicting the trajectory of the drift. To explore the feasibility and accuracy of predicting the trajectory of a drifting MODU based on hindcast met-ocean conditions and limited knowledge of the condition of the drifting MODU, this study employed a simplified equation describing only the horizontal (surge, sway and yaw) motions of a MODU under the impact of steady wind, current and wave forces. The simplified hydrodynamic model neglects the first- and second-order oscillatory wave forces, unsteady wind forces (owing to wind gustiness), wave drift damping, and the effects of the body oscillation on the steady wind and current forces. It was assumed that the net effects of the oscillatory forces on the steady motion are insignificant. To verify the accuracy and feasibility of our simplified approach, the predicted drifting trajectories of two MODUs were compared with the corresponding measurements recorded by the global positioning system (GPS).     

养殖大菱鲆细菌性红体病病原菌的分离与鉴定

从患有红体病的养殖大菱鲆(Scophthalmus maximus)的肌肉中分离得到一株优势菌并记为H1.经人工注射感染证实H1即为引起养殖大菱鲆红体病的病原菌,其半致死量LD50为2.82×105CFU/mL,而低浓度(1.41×103 CFU/mL)没有造成死亡,但注射部位有脓肿现象,注射相同体积1.5%无菌生理盐水的对照组没有明显的症状,注射部位也无异常.革兰氏染色显示该菌为革兰氏阴性,菌体呈杆状,周生鞭毛.综合该菌的形态、常规生理生化特征和API32E鉴定结果,发现H1与迟钝爱德华氏菌的表性特征非常相似,相似率迭到99.9%.在分子水平上对其16SRNA基因序列的测定,同源性分析,结果表明H1与迟钝爱德华氏菌的亲缘关系最近,相似度达到99%.综合上述研究结果,将该菌株初步鉴定为迟钝爱德华氏茵(Edwardsiella tarda).     

鲤鱼（Cyprinuscarpio L．）体重和体长QTL的定位

利用265个AFLP标记、127个微卫星分子标记、37个EST-SSR标记和16个RAPD标记（共445个标记）对大头鲤／荷包红鲤抗寒品系的F2代雌核发育群体44个个体进行基因型检测,构建鲤鱼（CyprinuscarpioL.）遗传连锁图谱;利用软件WinQTLCart2.5采用复合区间作图法对体重和体长两个性状进行了QTL定位分析。结果共检测到与两个与体重性状相关的QTL,分别定位到LG24连锁群（qBWh-24-1）和LG20连锁群（qBWh-20-1）上,可解释的表型变异分别为7.98％和20.05％;检测到两个与体长性状相关的QTL,分别位于LG2连锁群（qFS-2-1）和LG20连锁群（qFS-20-1）,可解释的表型变异分别为5.69％和12.69％,4个QTL的加性效应均为负值。     

Sacks��Ӧ����𲨵Ĺ۲�������

?о??????Sacks??????????????????????????????????????о??й????????????????????????о???????????????????????????????????о????????????????????????????6?Sacks??????????ε?????????????????????????????伫??????????????????????????????