Loss of ACTN3 gene function alters mouse muscle metabolism and shows evidence of positive selection in humans

More than a billion humans worldwide are predicted to be completely deficient in the fast skeletal muscle fiber protein alpha-actinin-3 owing to homozygosity for a premature stop codon polymorphism, R577X, in the ACTN3 gene. The R577X polymorphism is associated with elite athlete status and human muscle performance, suggesting that alpha-actinin-3 deficiency influences the function of fast muscle fibers. Here we show that loss of alpha-actinin-3 expression in a knockout mouse model results in a shift in muscle metabolism toward the more efficient aerobic pathway and an increase in intrinsic endurance performance. In addition, we demonstrate that the genomic region surrounding the 577X null allele shows low levels of genetic variation and recombination in individuals of European and East Asian descent, consistent with strong, recent positive selection. We propose that the 577X allele has been positively selected in some human populations owing to its effect on skeletal muscle metabolism.     

A recurrent mutation in MED12 leading to R961W causes Opitz-Kaveggia syndrome

Opitz-Kaveggia syndrome (also known as FG syndrome) is an X-linked disorder characterized by mental retardation, relative macrocephaly, hypotonia and constipation. We report here that the original family for whom the condition is named and five other families have a recurrent mutation (2881C>T, leading to R961W) in MED12 (also called TRAP230 or HOPA), a gene located at Xq13 that functions as a thyroid receptor-associated protein in the Mediator complex.     

Wnt-beta-catenin signaling initiates taste papilla development

Fungiform taste papillae form a regular array on the dorsal tongue. Taste buds arise from papilla epithelium and, unusually for epithelial derivatives, synapse with neurons, release neurotransmitters and generate receptor and action potentials. Despite the importance of taste as one of our five senses, genetic analyses of taste papilla and bud development are lacking. We demonstrate that Wnt-beta-catenin signaling is activated in developing fungiform placodes and taste bud cells. A dominant stabilizing mutation of epithelial beta-catenin causes massive overproduction of enlarged fungiform papillae and taste buds. Likewise, genetic deletion of epithelial beta-catenin or inhibition of Wnt-beta-catenin signaling by ectopic dickkopf1 (Dkk1) blocks initiation of fungiform papilla morphogenesis. Ectopic papillae are innervated in the stabilizing beta-catenin mutant, whereas ectopic Dkk1 causes absence of lingual epithelial innervation. Thus, Wnt-beta-catenin signaling is critical for fungiform papilla and taste bud development. Altered regulation of this pathway may underlie evolutionary changes in taste papilla patterning.     

钎焊后自然时效对3003/6xxx/3003复合铝合金性能和组织的影响

以6xxx系铝合金为芯材,3003铝合金为两侧皮材,经熔炼、铸造、复合、热轧、冷轧及成品退火制备了厚度为1.5 mm的3层复合铝合金。在600 ℃下模拟钎焊,经空冷后进行1、5、10、15、20、25、30 d的自然时效。结果显示：复合铝合金的强度、维氏硬度在自然时效初期快速增加,20 d后上升缓慢,30 d时抗拉强度、屈服强度、芯材维氏硬度达到最大,分别为242.3 MPa、122.9 MPa、84.0;芯材晶粒尺寸钎焊后较钎焊前略微长大,经不同自然时效时间的芯材晶粒平均尺寸大小相当,表明自然时效不改变芯材晶粒的大小;钎焊后以及经自然时效之后芯材中标识出的第二相为不规则的AlFeSiMnCu相。     

含未知输入非线性系统的扩展平方根容积卡尔曼滤波算法

针对工程实际应用中存在的未知输入会导致经典的非线性滤波器状态估计精度下降甚至滤波发散的问题,提出了一种基于最小方差无偏估计(minimum variance unbiased estimation, MVUE)准则的扩展平方根容积卡尔曼滤波(extended square-root cubature Kalman filter, ESRCKF)算法。首先,结合上一时刻未知输入估计值对状态一步预测值进行修正,得到含未知输入条件下的状态预测值。其次,设计新息并采用加权最小二乘(weighted least squares, WLS)法获取当前时刻未知输入的无偏估计。最后,通过最小化协方差矩阵的迹,同时采用拉格朗日乘子法和舒尔补引理得到系统状态的最小方差无偏估计。仿真结果表明,相比于现有的非线性滤波算法,ESRCKF算法提高了在处理含未知输入非线性系统时的状态估计精度,并能同时实现系统状态和未知输入的最优估计,验证了该算法的有效性。     

响应面结合模糊数学感官评价法优化槐花蜜饯配方及品质测定

以新鲜槐花为原料,辅以麦芽糖醇、柠檬酸、鸡蛋清和黄果槲寄生果实多糖等食品添加剂开发低糖槐花蜜饯。通过单因素试验,对鸡蛋清、麦芽糖醇、蜂蜜和黄果槲寄生果实多糖添加量进行筛选,采用响应面结合模糊数学感官评价法优化配方,对其重金属和微生物指标和抗氧化性进行了检验。结果表明,蜜饯最优化参数为鸡蛋清添加量为15%,麦芽糖醇添加量为30%,蜂蜜添加量为10%,黄果槲寄生果实多糖添加量为0.35%,柠檬酸量添加为0.18%、氯化钙添加量和D-异抗坏血酸钠添加量分别为0.01%为0.05%,得到了质地良好的槐花蜜饯产品,颜色均一微黄色,组织状态良好,薄厚均匀、口感细腻、咀嚼性好,槐花风味突出,气味协调。重金属含量低于国家标准限量（＜ 0.05 mg/kg）,未检出沙门氏菌和金黄色葡萄球菌,大肠杆菌和霉菌数量等卫生指标符合国家标准。蜜饯具有较强的总抗氧化能力（FRAP）和较好的清除 1,1-二苯基-2-三硝基苯肼（DPPH）的作用。研究结果表明,研制的低糖槐花蜜饯感官指标好,其质量符合国家标准,具有很好的营养价值和抗氧化功能。     

Asymptotic limits and stabilization for the 1D nonlinear Mindlin-Timoshenko system

<正> This paper shows how the so called von Karman model can be obtained as a singular limitof a modified Mindlin-Timoshenko system when the modulus of elasticity in shear k tends to infinity,provided a regularizing term through a fourth order dispersive operator is added.Introducing dampingmechanisms,the authors also show that the energy of solutions for this modified Mindlin-Timoshenkosystem decays exponentially,uniformly with respect to the parameter k.As k→∞,the authors obtainthe damped von Karman model with associated energy exponentially decaying to zero as well.     

Stability and change in fertility intentions in Britain, 1991-2007

The very low fertility experienced in several European countries in recent decades in the presence of higher intended family sizes has renewed interest in fertility intentions data. While the overall level of childbearing in Britain over the past few decades has remained relatively stable and high in comparison with many other European countries, we have seen sizeable increases in the age at which childbearing starts. This study uses data from the 1991 to 2007 General Household Surveys to examine trends in family intentions data in an attempt to arrive at a better understanding of these recent fertility developments. First, time trends in intended family size are compared with trends in observed fertility. Next, aggregate changes in intentions regarding the level and timing of fertility across the life course for cohorts are investigated together with the extent to which these aggregate intentions are matched by the subsequent childbearing of cohorts. Finally, both change across the life course and uncertainty in family intentions are examined. We conclude by discussing what these findings might tell us about contemporary reproductive decision making.