Central inputs mask multiple adult neural networks within a single embryonic network

It is usually assumed that, after construction of basic network architecture in embryos, immature networks undergo progressive maturation to acquire their adult properties. We examine this assumption in the context of the lobster stomatogastric nervous system. In the lobster, the neuronal population that will form this system is at first orgnanized into a single embryonic network that generates a single rhythmic pattern. The system then splits into different functional adult networks controlled by central descending systems; these adult networks produce multiple motor programmes, distinctively different from the single output of the embryonic network. We show here that the single embryonic network can produce multiple adult-like programmes. This occurs after the embryonic network is silenced by removal of central inputs, then pharmacologically stimulated to restore rhythmicity. Furthermore, restoration of the flow of descending information reversed the adult-like pattern to an embryonic pattern. This indicates that the embryonic network possesses the ability to express adult-like network characteristics, but descending information prevents it from doing so. Functional adult networks may therefore not necessarily be derived from progressive ontogenetic changes in networks themselves, but may result from maturation of descending systems that unmask preexisting adult networks in an embryonic system.     

Distributed biological computation with multicellular engineered networks

Ongoing efforts within synthetic and systems biology have been directed towards the building of artificial computational devices using engineered biological units as basic building blocks. Such efforts, inspired in the standard design of electronic circuits, are limited by the difficulties arising from wiring the basic computational units (logic gates) through the appropriate connections, each one to be implemented by a different molecule. Here, we show that there is a logically different form of implementing complex Boolean logic computations that reduces wiring constraints thanks to a redundant distribution of the desired output among engineered cells. A practical implementation is presented using a library of engineered yeast cells, which can be combined in multiple ways. Each construct defines a logic function and combining cells and their connections allow building more complex synthetic devices. As a proof of principle, we have implemented many logic functions by using just a few engineered cells. Of note, small modifications and combination of those cells allowed for implementing more complex circuits such as a multiplexer or a 1-bit adder with carry, showing the great potential for re-utilization of small parts of the circuit. Our results support the approach of using cellular consortia as an efficient way of engineering complex tasks not easily solvable using single-cell implementations.     

一种高效的生物网络概率模体发现算法

针对概率模体发现算法中非树形子图的挖掘和在得分函数最大化的过程中得分函数值计算的2个难点.首先提出基于划分的非树形子图的搜索算法,其次将子图同构应用于最小错配的求解以缩小智能优化算法对得分函数求解的解空间,最后将基于模拟退火算法和遗传算法的混合算法应用于得分函数的求解过程.在大肠杆菌基因调控网络中的实验结果表明,与其他算法相比,混合智能算法可以大大减少非树形子图的搜索时间,并以相对较快的收敛速度收敛到一个较优的解,因此所提出的方法有效地提高了概率模体发现的效率.     

含未知输入的非方离散广义系统的观测器设计与输入估计

研究了含未知输入的非方离散广义系统的输入解耦观测器设计问题．当系统脉冲能控时，把部分状态与未知输入一起作为新的未知输入，通过输入一状态对的非奇异变换，把非方离散广义系统的观测器设计问题等价地转化为离散正常状态空间系统的相应问题．给出了观测器存在的充分条件和简单的设计方法，并用观测器的状态，系统的控制输入和输出渐近地估计了系统的状态和未知输入．     

On A Few Reading Skills

This paper provides students with the contents and the forms of the materials they should read and with the methods and skills they should acquire. It also deals with the ways of how the students could raise their speed of reading. And it too, offers students some available principles and judicious suggestions.     

少极点的亚纯函数

设f,g是非常数亚纯函数,n是非负整数,a,6是f,g的小函数,其中     

三言两语话学习

不同的学科有自身特有的方法论,掌握相关的方法论对培养正确的思维方式和独立的科研能力有重要的作用。下面我想讲点学习中的个见和体会。     

BCI—代数中的几个结论

本文对BCI-代数一书中提出的二个未解决的问题:(1)是否存在一个局部完备的真BCH-代数而不是完备的BCH-代数;(2)是否存在极不BCI的BCH-代数给出了答案,同时得到一个结论:对在(2)中所讨论的有限BCI-代数,均是奇诣零代数。     

说"忽悠"

"忽悠"本为东北方言,近年来广泛流行于网络媒体中.本文分类总结其常见意义和用法,并探求其渊源,分析其流行的主客观原因.     

可化为对称情形的具有非对称权阵的连续Hopfield型神经网络

若非线性连续Ｈｏｐｆｉｅｌｄ型神经网络的非对称权阵能够分解为正定对角阵，对称阵与另一正定对角阵乘积，则该非称网络经过一似变换可化为具有等价和稳定性质且权阵为上述对称阵的神经网络。由此推出，该类非对称神经网络具有全局稳定的吸引子，且为它的非空的平衡点集。另得到了保证该类对称神经网络具有全局渐近稳定性的一个充分条件。     

导数教学中值得注意的几个问题

在导数概念的课堂教学中,指出学生容易混淆的几个相关概念,重点突出导数的本质,目的是让他们更好地理解和掌握导数的概念,注重培养学生的发散思维能力,拓展相应的知识面,同时,注重提高他们灵活地运用导数概念处理相关问题的能力.     

关于氧化数的几点质疑

化学种型中某元素原子的氧化数是个确定值,它与物质的组成、结构有关,其值不大于该元素的最高化台价。用电子转移和氧化数定义的氧化还原反应是等效的,但若采用后者需要谨慎。氧化数是个待完善的化学概念。     

具有较少非中心共轭类数的有限群

给出了非中心共轭类数介于6与9之间时有限群的结构,以及非中心共轭类数为10且基柱是可解群时有限群的结构.     

关于Lagrange中值定理的几点注记

文章对Lagrange中值定理的条件和结论进行了分析,指出了存在的问题,提出了几点注记。     

几类函数的可测性判定

从可测函数的定义出发根据可测函数的判定方法,总结推导出复合函数,多元函数及幂指函数等函数的可测性的判定定理.     

欠阻尼受迫振动的几个问题

振动分为欠阻尼振动、临界阻尼振动及过阻尼振动三种情形.对欠阻尼受迫振动的讨论更有意义,因此,讨论了欠阻尼振动系统的品质因数、欠阻尼受迫振动的振幅和初位相、振幅共振和速度共振、振动系统的带宽.     

一类含有独立干扰的线性奇异系统的函数观测器设计

研究了一类含有独立干扰的线性奇异系统的观测器设计,利用线性矩阵不等式方法给出了相应观测器的具体设计步骤,并对这类系统的降阶和全阶观测器设计的情况给出类似的结论说明。     

高阶等差数阵的若干性质

给出了高阶等差数阵的7个性质，并由此得到了Whc18的部分结论。