The underlying pathway structure of biochemical reaction networks

Bioinformatics is yielding extensive, and in some cases complete, genetic and biochemical information about individual cell types and cellular processes, providing the composition of living cells and the molecular structure of its components. These components together perform integrated cellular functions that now need to be analyzed. In particular, the functional definition of biochemical pathways and their role in the context of the whole cell is lacking. In this study, we show how the mass balance constraints that govern the function of biochemical reaction networks lead to the translation of this problem into the realm of linear algebra. The functional capabilities of biochemical reaction networks, and thus the choices that cells can make, are reflected in the null space of their stoichiometric matrix. The null space is spanned by a finite number of basis vectors. We present an algorithm for the synthesis of a set of basis vectors for spanning the null space of the stoichiometric matrix, in which these basis vectors represent the underlying biochemical pathways that are fundamental to the corresponding biochemical reaction network. In other words, all possible flux distributions achievable by a defined set of biochemical reactions are represented by a linear combination of these basis pathways. These basis pathways thus represent the underlying pathway structure of the defined biochemical reaction network. This development is significant from a fundamental and conceptual standpoint because it yields a holistic definition of biochemical pathways in contrast to definitions that have arisen from the historical development of our knowledge about biochemical processes. Additionally, this new conceptual framework will be important in defining, characterizing, and studying biochemical pathways from the rapidly growing information on cellular function.     

Management of blunt liver trauma in children

INTRODUCTION: Management of liver trauma in childhood represents a rare but formidable challenge. METHODS: Clinical presentation, grade of liver injury and Injury Severity Score (ISS) were studied in 11 cases of blunt liver trauma to examine factors influencing outcome. RESULTS: Seven of the 11 children were injured severely and had an ISS greater than 16. Seven who were haemodynamically stable were treated without operation, but four required surgery for grade III, IV and V liver injuries. Two children had primary repair of hepatic lacerations. Perihepatic packing was employed in two other cases (grade IV and V injury) for uncontrollable haemorrhage. Delayed debridement and thrombectomy plus vena cava repair with suturing of liver lacerations in these patients obviated heroic efforts at primary repair. Nine children survived. There were two deaths from head and neck trauma. DISCUSSION: Selected children with liver trauma can be managed non-operatively using established trauma guidelines. Perihepatic packing is recommended in unstable patients with complex injuries, followed by delayed definitive repair.     

低温供热堆推荐动力循环

分析了低温供热堆热电联供所提供的热源和冷源的特点，根据５ＭＷ、２００ＭＷ、５００ＭＷ低温供热堆的设计工况，针对氨水朗肯循环、水蒸汽朗肯循环、水蒸汽扩容循环、卡林那循环和氦气循环等动力循环方式，进行了详细计算、分析、比较。结果表明，氨水朗肯循环具有相对较高的发电效率，是一种很有潜力的低温动力循环；水蒸汽朗肯循环对于堆芯进、出口温度差较小的堆型具有明显的优势；而水蒸汽扩容循环却是堆芯进、出口温度差较大堆型的首选循环。     

中国液压抽油机的发展概况与技术水平

液压抽油机是已被国内外油田生产实践所证实了的具有采油经济性好、重量轻、体积小、冲程长度及冲程次数可实现无级调节和工作性能优越等特点的新型抽油设备。目前液压抽油机已得到国内油田工程技术人员的高度重视 ,使液压抽油机近十几年来得到了迅速发展 ,并在油田生产中得到了一定的应用 ,文中仅对国内液压抽油机发展概况及技术现状作简要介绍     

卤化铊晶体折射率温度系数的理论研究

研究了卤化铊晶体的折射率温度效应,结果表明晶格常数变化引起的带宽变化对这类晶体折射率温度系数的影响不可忽视,且是负贡献。理论算得的折射率温度系数与实验结果一致。     

适用于半桥型MMC附加限流控制的直流线路纵联保护方案

半桥型模块化多电平换流器的附加限流控制能有效降低对线路保护速动性的要求、增强实体限流装置的限流效果,降低了故障暂态电流的上升梯度及其幅值,因此,基于故障暂态电流信息的直流线路保护会受到限流控制器影响。提出了计及附加限流控制器影响的直流线路自适应纵联保护方案：利用极线电压及其零模电压变化率构成或逻辑来启动限流控制器;推导了限流控制器作用下的直流侧故障电流解析关系,并根据限流控制器对故障电流抑制程度和换流阀两侧的故障电流信息,建立了一种基于换流阀两侧差流的纵联保护方案。该方案仅用到各站端的本地量,通过与其对端换流站交换判别结果,其不受线路分布电容影响、无需多端数据同步,具有自适应性。大量仿真实验验证了利用限流控策略的有效性和保护方案的可靠性。     

基于SCADA参量关联互信息自编码的风电机组故障检测方法

针对风力发电机组数据采集与监视控制系统(supervisory control and data acquisition,SCADA)监测参量间的耦合关联性,提出基于多参数耦合关联互信息编码的风电机组故障检测方法.该方法构建了SCADA数据的耦合关联矩阵,采用互信息变分自编码器对关联矩阵进行编码重构;将SCADA参量关联矩阵的重构误差作为机组健康评估指标,结合指数加权移动平均模型的迭代更新,对机组实时故障阈值进行自适应设置.两个风场的风电机组SCADA数据分析结果表明,所提方法充分利用了SCADA数据的耦合关联结构信息,能有效提高风电机组故障检测的准确性及对环境工况的鲁棒性.     

关于做好地质系统重塑性改革“后半篇文章”的探讨——以河南省为例

2022年5月,通过施行重塑性改革,河南地质系统形成了“一局一院一集团”的地质工作新架构。为了推进新机构职能优化协同高效,更好地履行创新服务职能,推动河南地质事业高质量发展,本文收集和整理了河南地质系统重塑性改革现状和问题资料,采用团体调查、问题调查分析等方法对重塑性改革后面临的“后半篇文章”进行分析、探讨,着力在落实地质行业“一局一院一集团”新架构优势、建设地质豫军、打造地勘“航母”方面查问题、找堵点、谋思路。提出了做好重塑性改革“后半篇文章”的建议：落实组建方案红利性政策,稳定地质队伍;聚焦主责主业,做到专心专注;聚焦高质量发展,破除障碍、梗阻。     

大跨度预应力混凝土连续梁预应力损失研究

针对连续梁桥常见的预应力损失问题,从3个方面进行了详细的介绍,首先与简支梁受力做对比,分析了开兰特大连续梁桥结构受力和从"强梁弱墩"角度讲述了连续梁桥的受力特征,接着介绍了预应力损失估算方法和预应力损失对于连续梁桥的影响,如引起腹板斜裂缝甚至跨中下挠严重,最后针对预应力损失,针对性的提出施加体外预应力和粘贴钢板的措施,可以起到较好的加固补强效果.希望为今后类似工程提供可资借鉴的经验.     

基于新型粒子群优化的粒子滤波雷达目标跟踪算法

针对基于粒子群优化算法的粒子滤波精度不高,容易陷入局部最优,难以满足目标跟踪的问题,提出了一种新的粒子群优化粒子滤波算法,该算法利用社会个体对群体的认知规律优化了粒子更新的方法,并且完善了粒子速度的更新策略,使优势速度有较小概率变异,从而提高了寻优能力,同时将劣势速度随机初始化,保证了样本的多样性.实验结果表明,该算法精度高,鲁棒性强,可以有效地应用于雷达机动目标跟踪.